WorldWideScience

Sample records for residual nitrite concentration

  1. Influence of turkey meat on residual nitrite in cured meat products.

    Science.gov (United States)

    Kilic, B; Cassens, R G; Borchert, L L

    2001-02-01

    A response surface experimental design was employed to estimate residual nitrite level at various initial nitrite concentrations, percent turkey meat in the formula, and heat quantity (F) values using a typical wiener as the test system. Pork and mechanically separated turkey were used as the meat ingredients. Residual nitrite and pH were measured at day 1, 7 days, 14 days, and 49 days after processing. Protein, fat, salt, moisture, and CIE (L*a*b*) color values were also determined. Results showed that the effect of turkey meat on residual nitrite level was significant (P meat in the formula resulted in lower residual nitrite levels at a fixed pH. The residual nitrite level was initially proportional to initial nitrite concentration, but it became a nonsignificant factor during longer storage time. Differences in heat quantity had a significant effect (P nitrite level initially. Greater heat quantity decreased residual nitrite level in finished cured meat products at a fixed pH. However, this effect became nonsignificant during longer storage. Reduction of residual nitrite in wieners because of turkey meat addition at a fixed pH was due to characteristics of the turkey tissue, but the mechanism of action remains unknown. It was also established that commercial wieners had a higher pH if poultry meat was included in the formulation.

  2. Simultaneous determination of nitrite and nitrate residues in meat products marketed in Shiraz by high performance liquid chromatography

    Directory of Open Access Journals (Sweden)

    H Golkari

    2012-08-01

    Full Text Available Nitrite and nitrate are the key ingredients and play a multifunctional role in meat curing technology. Despite all of their desirable effects, the addition of nitrite to meat is the major cause of carcinogenic N-nitrosamines formation. In this study, the amount of residual nitrite and nitrate in meat products containing 61% to 80% meat were assessed. The samples were obtained at the fourth day of their production from Shiraz retails and analyzed using high performance liquid chromatography (HPLC. According to the results, the mean concentrations of residual nitrite and nitrate were estimated at 36.96 ± 7.38 and 85.81 ± 5.5 mg/kg in small-diameter (1.5-2 cm sausages. Meanwhile, in large-diameter (5.5-8 cm sausages the residues were estimated at 20.97 ± 3.28 and 124.85±5.3 mg/kg, respectively. In all analyzed samples, the residual nitrite level was found below the permitted level of 120 mg/kg which indicated the application of allowed concentrations of nitrite in such products. The mean values of residual nitrite and nitrate concentrations were statistically different (p

  3. Residual Nitrite in Some Egyptian Meat Products and the Reduction Effect of Electron Beam Irradiation

    OpenAIRE

    Dalia A. Zahran; Gehan M.A. Kassem

    2011-01-01

    Nitrite, a curing agent of meat products, is a precursor of carcinogenic N-nitrosamines during processing of meat products or under human stomach conditions, as well as having its own toxicity. To investigate the residual nitrite level in meat products marketed in Egyptian markets, 160 samples of cured cooked (luncheon and frankfurter) and cured raw (oriental sausages and pastirma) meat products (40 sample each) were analyzed for residual nitrite by a spectrophotometric method. Samples were s...

  4. Irradiation and modified atmosphere packaging effects on residual nitrite, ascorbic acid, nitrosomyoglobin, and color in sausage.

    Science.gov (United States)

    Ahn, Hyun-Joo; Jo, Cheorun; Lee, Ju-Woon; Kim, Jae-Hyun; Kim, Kee-Hyuk; Byun, Myung-Woo

    2003-02-26

    The present study was undertaken to evaluate the irradiation and modified atmosphere packaging effects on emulsion-type cooked pork sausage during storage for 4 weeks. CO(2) (100%), N(2) (100%), or 25% CO(2)/75% N(2) packaged sausage were irradiated at 0, 5, and 10 kGy, and residual nitrite, residual ascorbic acid, nitrosomyoglobin (NO-Mb), color values, and their correlation were observed. Irradiation significantly reduced the residual nitrite content and caused partial reduction of NO-Mb during storage. No difference was observed in ascorbic acid content by irradiation. Irradiation decreased the Hunter color a value of sausage. CO(2) or CO(2)/N(2) packaging were more effective for reducing residual nitrite and inhibiting the loss of the red color of sausage compared to N(2) packaging. Results indicated that the proper combination of irradiation and modified atmosphere packaging could reduce the residual nitrite in sausage with minimization of color change.

  5. Effect of gamma radiation on residual nitrate and nitrite in some meat and chicken products

    International Nuclear Information System (INIS)

    Afifi, S.A.; Abdel-Daiem, M.H.

    2006-01-01

    This study was carried out to establish the residual nitrate and nitrite and concentrations of six heavy metals in meat products samples that purchased from retail outlets in Sharkia governorate, Egypt. The possibility of using gamma irradiation at doses of 3, 5 and 7 KGy for reducing residual nitrate and nitrite was studied. The results showed that most of samples under investigation above the maximum permissible limit of nitrate in Egypt. Gamma irradiation at doses of 3, 5 and 7 KGy reduced the levels of nitrate and nitrite proportionally to applied doses. The irradiation dose of 7 KGy was more effective for reducing the level of residual nitrate and nitrite. Heavy metals concentrations were determined using the inductively coupled plasma spectrometry (ICPS) in non-irradiated samples. The results showed that the concentration of Pb in meat products was ranged between 0.643-0.828, 0.548, 0.598-0.844, 0.574-0.877, 0.324-0.568 and 0.156-0.432 mg/kg (wet weight basis) in pastirma, chicken luncheon, fresh sausages, burger, minced chicken and minced beef meat, respectively, but the values of Hg ranged between 0.0965-0.839, 0.121, 0.147-0.218, 0.114-0.258, 0.087-0.143 and 0.057-0.124 mg/kg in pastirma, chicken luncheon, fresh sausages, burger, minced chicken and beef meat, respectively. The content of iron ranged between 0.336, 0.362-4.284, 0.364-0.611, 0.264-0.336 and 0.276-0.314 mg/kg in chicken luncheon, fresh sausages, burger, minced chicken and beef meat, respectively. However, the results indicated that, the most of meat products under investigation had high concentrations from toxic metals of Pb and Hg than the permissible limits that recommended by FAO/WHO of person daily. Therefore, the consumption of high amount of these commodities dose not pose a health risk for the consumer

  6. Effect of Dry Red Grape Pomace as a Nitrite Substitute on the Microbiological and Physicochemical Properties and Residual Nitrite of Dry-cured Sausage

    Directory of Open Access Journals (Sweden)

    Fatemeh Riazi

    2016-07-01

    Full Text Available Background and Objectives: Sodium nitrite and potassium nitrite have been traditionally used for inhibition of Clostridium botulinum and also as an agent to stabilize the color of meat products; however, usage of these additives at high levels could lead to toxicity and cancer originating from the formation of nitrosamines. Nowadays, application of natural preservatives in order to reduce the nitrite content in meat products is increasing. Thus, we used dry red grape pomace (DRGP as a natural alternative to sodium nitrite. Materials and Methods: The effect of two levels of DRGP (1 and 2% on the proximate composition, microbial counts, pH values and residual nitrite level of the samples formulated with two levels of sodium nitrite (30 and 60 mg/kg, as well as the comparison of these sausages with the blank (nitrite-free  and control (full nitrite added samples on the 1rst, 10th, 20th and 30th days of storage at 3-5 °C were evaluated. Results: The results showed that all chemical compositions were in the ranges reported by other researchers, and nitrite was very effective in preventing the microbial growth. Also about 50 % of the ingoing nitrite could be analyzed in the samples after processing. Moreover, the residual nitrite level declined both during the storage of sausage and after the addition of DRGP. Conclusions: The use of DRGP in combination with nitrite for sausages was more effective in keeping the quality and safety of the refrigerated consumer products as indicated by the lower nitrite levels, microbial count and similar composition as compared to the samples treated with nitrite and without nitrite. Keywords: Dry red grape pomace (DRGP, Sausage, Nitrite, Microbial count

  7. Effect of residual ascorbate on determination of nitrite in commercial cured meat products.

    Science.gov (United States)

    Fox, J B; Doerr, R C; Gates, R

    1984-01-01

    Residual ascorbate in cured meat slurries results in different amounts of pigment being produced from different Griess reagent combinations. The phenomenon was used to study residual ascorbate in commercial cured meat products which had a variety of textures, acidities, moisture and meat content, fat, homogeneity, initial nitrite, and processing conditions. Diluting and heating the samples according to the AOAC procedure did not completely eliminate the ascorbate interference, but making the sample alkaline did. Determining nitrite separately in supernate and precipitate from the first dilution showed the effect of heating to be the elimination of interferences and solubilization or extraction of nitrite from the precipitate.

  8. Monitoring nitrite and nitrate residues in frankfurters during processing and storage.

    Science.gov (United States)

    Pérez-Rodríguez, M L; Bosch-Bosch, N; Garciá-Mata, M

    1996-09-01

    Frankfurter-type sausages were prepared in a pilot plant with different concentrations of NaNO(2) (75, 125 or 250 ppm) combined or not with 200 ppm KNO(3). A meat system, free of curing agents, was also used as control. Nitrite and nitrate levels were tested in various processing steps and over 120 days storage at 3 °C of the vacuum-packaged frankfurters. Little influence of the originally added nitrite level on the amount of nitrate formed was observed. Important losses of nitrite and nitrate were due to cooking. Thereafter about 50% of the nitrite added initially remained in this form in all samples (39, 59 and 146 ppm, respectively) and between 10 and 15% as nitrate. When only nitrate was initially added, formation of nitrite after cooking was observed (maximum level 43 ppm NaNO(2)). Formulations prepared with both nitrate and nitrite showed no significant differences (p nitrite or nitrate counterparts. A good correlation among nitrite and nitrate levels and storage time was showed by multiple linear regression analysis. It is concluded that the use of nitrate in combination with nitrite in cooked meat products seems to have little technological significance and adds to the total body burden of nitrite.

  9. Optimization of free ammonia concentration for nitrite accumulation in shortcut biological nitrogen removal process.

    Science.gov (United States)

    Chung, Jinwook; Shim, Hojae; Park, Seong-Jun; Kim, Seung-Jin; Bae, Wookeun

    2006-03-01

    A shortcut biological nitrogen removal (SBNR) utilizes the concept of a direct conversion of ammonium to nitrite and then to nitrogen gas. A successful SBNR requires accumulation of nitrite in the system and inhibition of the activity of nitrite oxidizers. A high concentration of free ammonia (FA) inhibits nitrite oxidizers, but unfortunately decreases the ammonium removal rate as well. Therefore, the optimal range of FA concentration is necessary not only to stabilize nitrite accumulation but also to achieve maximum ammonium removal. In order to derive such optimal FA concentrations, the specific substrate utilization rates of ammonium and nitrite oxidizers were measured. The optimal FA concentration range appeared to be 5-10 mg/L for the adapted sludge. The simulated results from the modified inhibition model expressed by FA and ammonium/nitrite concentrations were shown very similar to the experimental results.

  10. Intermediates detected by visible spectroscopy during the reaction of nitrite with deoxyhemoglobin: the effect of nitrite concentration and diphosphoglycerate.

    Science.gov (United States)

    Nagababu, Enika; Ramasamy, Somasundaram; Rifkind, Joseph M

    2007-10-16

    The reaction of nitrite with deoxyhemoglobin (deoxyHb) results in the reduction of nitrite to NO, which binds unreacted deoxyHb forming Fe(II)-nitrosylhemoglobin (Hb(II)NO). The tight binding of NO to deoxyHb is, however, inconsistent with reports implicating this reaction with hypoxic vasodilation. This dilemma is resolved by the demonstration that metastable intermediates are formed in the course of the reaction of nitrite with deoxyHb. The level of intermediates is quantitated by the excess deoxyHb consumed over the concentrations of the final products formed. The dominant intermediate has a spectrum that does not correspond to that of Hb(III)NO formed when NO reacts with methemoglobin (MetHb), but is similar to metHb resulting in the spectroscopic determinations of elevated levels of metHb. It is a delocalized species involving the heme iron, the NO, and perhaps the beta-93 thiol. The putative role for red cell reacted nitrite on vasodilation is associated with reactions involving the intermediate. (1) The intermediate is less stable with a 10-fold excess of nitrite and is not detected with a 100-fold excess of nitrite. This observation is attributed to the reaction of nitrite with the intermediate producing N2O3. (2) The release of NO quantitated by the formation of Hb(II)NO is regulated by changes in the distal heme pocket as shown by the 4.5-fold decrease in the rate constant in the presence of 2,3-diphosphoglycerate. The regulated release of NO or N2O3 as well as the formation of the S-nitroso derivative of hemoglobin, which has also been reported to be formed from the intermediates generated during nitrite reduction, should be associated with any hypoxic vasodilation attributed to the RBC.

  11. 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.

  12. Spectrofluorometric and Molecular Modeling Studies on Binding of Nitrite Ion with Bovine Hemoglobin: Effect of Nitrite Ion on Amino Acid Residues

    Science.gov (United States)

    Madrakian, T.; Bagheri, H.; Afkhami, A.

    2015-05-01

    The interaction between nitrite ion and bovine hemoglobin was investigated by a spectrofluorometric technique. The experimental results indicated that the interaction causes a static quenching of the fluorescence of bovine hemoglobin, that the binding reaction is spontaneous, and that H-bonding interactions play a major role in binding of this ion to bovine hemoglobin. The formation constant for this interaction was calculated. Based on Förster's theory of nonradiative energy transfer, the binding distance between this ion and bovine hemoglobin was determined. Furthermore, the interaction of nitrite ion with tyrosine and tryptophan was investigated with synchronous fluorescence. There was no significant shift of the maximum emission wavelength with interactions of the mentioned ion with bovine hemoglobin, which implies that interaction of nitrite ion with bovine hemoglobin does not affect the microenvironment around the tryptophan and tyrosine residues. Furthermore, the effect of nitrite ion on amino acid residues of bovine hemoglobin was studied by a molecular docking technique.

  13. Effects of high hydrostatic pressure and varying concentrations of sodium nitrite from traditional and vegetable-based sources on the growth of Listeria monocytogenes on ready-to-eat (RTE) sliced ham.

    Science.gov (United States)

    Myers, Kevin; Cannon, Jerry; Montoya, Damian; Dickson, James; Lonergan, Steven; Sebranek, Joseph

    2013-05-01

    The objective of this study was to determine the effect the source of added nitrite and high hydrostatic pressure (HHP) had on the growth of Listeria monocytogenes on ready-to-eat (RTE) sliced ham. Use of 600MPa HHP for 3min resulted in an immediate 3.9-4.3log CFU/g reduction in L. monocytogenes numbers, while use of 400MPa HHP (3min) provided less than 1log CFU/g reduction. With the 600MPa HHP treatment, sliced ham with a conventional concentration of sodium nitrite (200ppm) was not different in L. monocytogenes growth from use with 50 or 100ppm of sodium nitrite in pre-converted celery powder. Instrumental color values as well as residual nitrite and residual nitrate concentrations for cured (sodium nitrite and nitrite from celery powder) and uncured ham formulations are discussed. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Evaluation of Total Nitrite Pattern Visualization as an Improved Method for Gunshot Residue Detection and its Application to Casework Samples.

    Science.gov (United States)

    Berger, Jason; Upton, Colin; Springer, Elyah

    2018-04-23

    Visualization of nitrite residues is essential in gunshot distance determination. Current protocols for the detection of nitrites include, among other tests, the Modified Griess Test (MGT). This method is limited as nitrite residues are unstable in the environment and limited to partially burned gunpowder. Previous research demonstrated the ability of alkaline hydrolysis to convert nitrates to nitrites, allowing visualization of unburned gunpowder particles using the MGT. This is referred to as Total Nitrite Pattern Visualization (TNV). TNV techniques were modified and a study conducted to streamline the procedure outlined in the literature to maximize the efficacy of the TNV in casework, while reducing the required time from 1 h to 5 min, and enhancing effectiveness on blood-soiled samples. The TNV method was found to provide significant improvement in the ability to detect significant nitrite residues, without sacrificing efficiency, that would allow for the determination of the muzzle-to-target distance. © 2018 American Academy of Forensic Sciences.

  15. 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.)

  16. Ammonium and nitrite oxidation at nanomolar oxygen concentrations in oxygen minimum zone waters.

    Science.gov (United States)

    Bristow, Laura A; Dalsgaard, Tage; Tiano, Laura; Mills, Daniel B; Bertagnolli, Anthony D; Wright, Jody J; Hallam, Steven J; Ulloa, Osvaldo; Canfield, Donald E; Revsbech, Niels Peter; Thamdrup, Bo

    2016-09-20

    A major percentage of fixed nitrogen (N) loss in the oceans occurs within nitrite-rich oxygen minimum zones (OMZs) via denitrification and anammox. It remains unclear to what extent ammonium and nitrite oxidation co-occur, either supplying or competing for substrates involved in nitrogen loss in the OMZ core. Assessment of the oxygen (O2) sensitivity of these processes down to the O2 concentrations present in the OMZ core (Chile at manipulated O2 levels between 5 nmol⋅L(-1) and 20 μmol⋅L(-1) Rates of both processes were detectable in the low nanomolar range (5-33 nmol⋅L(-1) O2), but demonstrated a strong dependence on O2 concentrations with apparent half-saturation constants (Kms) of 333 ± 130 nmol⋅L(-1) O2 for ammonium oxidation and 778 ± 168 nmol⋅L(-1) O2 for nitrite oxidation assuming one-component Michaelis-Menten kinetics. Nitrite oxidation rates, however, were better described with a two-component Michaelis-Menten model, indicating a high-affinity component with a Km of just a few nanomolar. As the communities of ammonium and nitrite oxidizers were similar to other OMZs, these kinetics should apply across OMZ systems. The high O2 affinities imply that ammonium and nitrite oxidation can occur within the OMZ core whenever O2 is supplied, for example, by episodic intrusions. These processes therefore compete with anammox and denitrification for ammonium and nitrite, thereby exerting an important control over nitrogen loss.

  17. Effect of nitrite concentration on pit depth in carbon steel exposed to simulated radioactive waste

    International Nuclear Information System (INIS)

    Zapp, P.E.

    1997-01-01

    The growth of pits in carbon steel exposed to dilute (0.055 M nitrate-bearing) alkaline salt solutions that simulate radioactive waste was investigated in coupon immersion tests. Most coupons were tested in the as-received condition, with the remainder having been heat treated to produce an oxide film. Nitrite, which is an established pitting inhibitor in these solutions, was present in concentrations from 0 to 0.031 M to 0.16 M; the last concentration is known to prevent pitting initiation in the test solution at the 50 degrees C test temperature. The depths of the deepest pits on coupons of particular exposure conditions were measure microscopically and were analyzed as simple, type 1 extreme value statistical distributions, to predict the deepest expected pit in a radioactive waste tank subject to the test conditions. While the growth rate of pits could not be established from these tests, the absolute value of the deepest pits predicted is of the order of 100 mils after 448 days of exposure. The data indicate that even nitrite concentrations insufficient to prevent pitting have a beneficial effect on limiting the growth of deepest pits

  18. Effect of Dry Red Grape Pomace as a Nitrite Substitute on the Microbiological and Physicochemical Properties and Residual Nitrite of Dry-cured Sausage

    OpenAIRE

    Fatemeh Riazi; Fariba Zeynali; Ebrahim Hoseini; Homa Behmadi

    2016-01-01

    Background and Objectives: Sodium nitrite and potassium nitrite have been traditionally used for inhibition of Clostridium botulinum and also as an agent to stabilize the color of meat products; however, usage of these additives at high levels could lead to toxicity and cancer originating from the formation of nitrosamines. Nowadays, application of natural preservatives in order to reduce the nitrite content in meat products is increasing. Thus, we used dry red grape pomace (DRGP) as a natura...

  19. Effects of Lactic Acid Bacteria on Residual Nitrite in a Summer Style Sausage.

    Science.gov (United States)

    1984-01-01

    Lactobacillus plantarum 4008 Lactobacillus bulgaricus 11842 Lactobacillus fermentum 9338 Lactobacillus casei subsp. rhamnosus 7469 Pediococcus acidilactici...the American Type Culture Collection Culture ATCC Number Lactobacillus acidophilus 4365 0 Lactobacillus casei E393 Lactobacillus leichmannii 4797...sources (e.g., Micrococcus varians, Lactobacillus plantarum) exhibited different nitrite reducing abilities. Lactobacillus leichmannii (

  20. 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.

  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. 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.

  3. Application of Ganghwa Mugwort in Combination with Ascorbic Acid for the Reduction of Residual Nitrite in Pork Sausage during Refrigerated Storage

    Science.gov (United States)

    Hwang, Ko-Eun; Kim, Hyun-Wook; Song, Dong-Heon; Kim, Yong-Jae; Ham, Youn-Kyung; Lee, Choong-Hee; Choi, Yun-Sang; Kim, Cheon-Jei

    2014-01-01

    The application of ganghwa mugwort (GM), ascorbic acid (AC), and their combinations for reduction of residual nitrite contents was analyzed in pork sausages during storage of 28 d. Six treatments of pork sausages contained the following: Control (no antioxidant added), AC (0.05% AC), GM 0.1 (0.1% GM), GM 0.2 (0.2% GM), AC+GM 0.1 (0.05% AC + 0.1% GM) and AC+GM 0.2 (0.05% AC + 0.2% GM). Results showed that the mixture of 0.05% AC and 0.2% GM was most effective for reducing thiobarbituric acid reactive substances (TBARS) and residual nitrite contents than the control and GM added sausages alone (pcolor values of all treatments were significantly affected by adding GM (either alone or with AC). Additionally, the total color difference (ΔE) and hue angle (H°) values of treatments added with GM were higher than those of the control as the amount of GM increased (p0.05). Our results showed possible applications of antioxidant combination, for preventing the lipid oxidation and decreasing the residual nitrite levels of meat products. PMID:26760936

  4. The use of atmospheric pressure plasma-treated water as a source of nitrite for emulsion-type sausage.

    Science.gov (United States)

    Jung, Samooel; Kim, Hyun Joo; Park, Sanghoo; In Yong, Hae; Choe, Jun Ho; Jeon, Hee-Joon; Choe, Wonho; Jo, Cheorun

    2015-10-01

    We investigated the possible use of atmospheric pressure plasma-treated water (PTW) as a nitrite source in curing process. Emulsion-type sausages were manufactured with PTW, celery powder containing nitrite, and synthetic sodium nitrite at a concentration of nitrite ion 70mgkg(-1). In terms of sausage quality, there were no noticeable effects of PTW on the total aerobic bacterial counts, color, and peroxide values of sausages compared with those of celery powder and sodium nitrite throughout 28days of storage at 4°C. Sausage with added PTW had lower concentrations of residual nitrite compared to those of added celery powder and sodium nitrite during the storage period (Pnitrite-treated sausages were not different, whereas the sausage with added celery powder received the lowest scores in taste and acceptability. From the results, it is concluded that PTW can be used as a nitrite source equivalent to a natural curing agent. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Effects of varying levels of vegetable juice powder and incubation time on color, residual nitrate and nitrite, pigment, pH, and trained sensory attributes of ready-to-eat uncured ham.

    Science.gov (United States)

    Sindelar, J J; Cordray, J C; Sebranek, J G; Love, J A; Ahn, D U

    2007-08-01

    Vegetable juice powder (VJP) and a starter culture containing Staphylococcus carnosus have been identified as necessary ingredients for the manufacture of uncured, no-nitrate/nitrite-added meat products with quality and sensory attributes similar to traditional cured products. The objectives of this study were to determine the effects of varying concentrations of VJP and incubation time (MIN-HOLD) on quality characteristics, including lipid oxidation, color, and cured meat pigment concentrations, of ham over a 90-d storage period, compare residual nitrate and nitrite content, and determine if differences exist in sensory properties of finished products. Four ham treatments (TRT) (TRT 1: 0.20% VJP, 0 MIN-HOLD; TRT 2: 0.20% VJP, 120 MIN-HOLD; TRT 3: 0.35% VJP, 0 MIN-HOLD; TRT 4: 0.35% VJP, 120 MIN-HOLD) and a sodium nitrite-added control (C) were used for this study. No differences (P > 0.05) were observed between TRTs and C for CIE L*, a*, b*, and cured color measured by reflectance ratio. Lipid oxidation (TBARS) for combined TRTs and C revealed little change over time while the C had less (P 0.05) were reported for cured pigment concentration between TRTs and C. Trained sensory panel intensity ratings for ham and vegetable aroma, and flavor, color, and firmness showed that a high concentration (0.35%) of VJP resulted in the highest scores for undesirable vegetable aroma and flavor. Treatment combinations with a low concentration (0.20%) of VJP were comparable to the C for all sensory attributes.

  6. The Sensory Properties, Color, Microbial, Lipid Oxidation, and Residual Nitrite of Se’i Marinated with Lime and Roselle Calyces Extracts

    Directory of Open Access Journals (Sweden)

    G. E. M. Malelak

    2017-12-01

    Full Text Available Meat deterioration can occur because of lipid oxidation and bacteria that could affect meat quality. It has been recognized that fruits of lime (Citrus aurantifolia and roselle (Hibiscus sabdariffa calyces contain bioactive compounds that have a capability to prevent oxidation and bacterial growth. The objective of this research was to  investigate the effect of lime and roselle calyces extracts on se’i (Rotenese smoked beef quality. Completely randomized design (CRD with 2x4 factorial pattern was used in this study. The first factor (E was source of extracts i.e., lime extract (E1 and roselle extract (E2. The second factor (L was level of the extract consisted of 4 levels i.e., control (without extract/ L0; L1= 1%; L2= 2%; and L3= 3% (v/v. Each treatment consisted of 3 replications. Sensory properties measured were aroma, taste, and tenderness. Other variables measured were color, total plate count (TPC, thiobarbituric acid reactive substances (TBARS, and residual nitrite.  The taste and tenderness of se’i were affected (P<0.05 by combination of the extract and the level of the extract.  Results showed that there were significant interactions (P<0.05 between the kind of extracts and the level of extract on L (lightness, a (redness, and b (yellowness values, TPC, TBARS, and residual nitrite values. The level of 3% of  lime extract as well as 3% of roselle calyces extract improved score of taste and tenderness, reduced a values, decreased TPC, TBARS, and residual nitrite values. Marinating in 3% of roselle calyces extract decreased the b value but marinating in 3% of lime increased the b value of se’i. It is concluded that marinating 3% of roselle or 3% of lime gives the best effect on taste, tenderness, TPC, and TBARS values of se’i.

  7. The use and control of nitrate and nitrite for the processing of meat products.

    Science.gov (United States)

    Honikel, Karl-Otto

    2008-01-01

    Nitrate and nitrite are used for the purpose of curing meat products. In most countries the use of both substances, usually added as potassium or sodium salts, is limited. Either the ingoing or the residual amounts are regulated by laws. The effective substance is nitrite acting primarily as an inhibitor for some microorganisms. Nitrite added to a batter of meat is partially oxidized to nitrate by sequestering oxygen - thus it acts as an antioxidant - a part of nitrite is bound to myoglobin, forming the heat stable NO-myoglobin, a part is bound to proteins or other substances in meat. Nitrate may be reduced to nitrite in raw meat products by microorganisms. As oxidation and reduction may occur the concentrations of nitrite plus nitrate in a product has to be controlled and measured especially if the residual amounts are regulated. This sum of both compounds is important for the human body. Intake of nitrate with food leads to its absorption over the digestive tract into the blood. In the oral cavity nitrate appears again where it is reduced to nitrite. With the saliva the nitrite is mixed with food, having the same effect as nitrite in a batter (inhibiting growth of some pathogenic microorganisms) and swallowed. In the stomach nitrite can eventually form carcinogenic nitrosamines in the acidic environment.

  8. Influence of Estimated Training Status on Anti and Pro-Oxidant Activity, Nitrite Concentration, and Blood Pressure in Middle-Aged and Older Women.

    Science.gov (United States)

    Jacomini, André M; Dias, Danielle da Silva; Brito, Janaina de Oliveira; da Silva, Roberta F; Monteiro, Henrique L; Llesuy, Susana; De Angelis, Kátia; Amaral, Sandra L; Zago, Anderson S

    2017-01-01

    The purpose of this study was to compare the association between anti and pro-oxidant activity, nitrite concentration, and blood pressure (BP) in middle-aged and older women with different levels of estimated training status (TS). The sample consisted of 155 females (50-84 years) who were submitted to a physical examination to evaluate estimated TS through the "Functional Fitness Battery Test," BP measurements, and plasma blood samples to evaluate pro-oxidant and antioxidant activity and nitrite concentrations. Participants were separated by age into a middle-aged group (<65 years) and an older (≥65 years) group and then subdivided in each group according to TS. Blood biochemistry was similar between groups. On the other hand, protein oxidation was lower in participants with higher TS, independent of age. Older females with higher TS presented higher nitrite concentrations, lower lipoperoxidation, and lower values of BP compared with those with lower TS. Lower GPx activity was observed in participants with higher TS compared with middle-aged with lower TS. Thus, our results suggest that good levels of TS may be associated with lower oxidative stress and higher nitrite concentration and may contribute to maintain normal or reduced blood pressure values.

  9. Influence of Estimated Training Status on Anti and Pro-Oxidant Activity, Nitrite Concentration, and Blood Pressure in Middle-Aged and Older Women

    Science.gov (United States)

    Jacomini, André M.; Dias, Danielle da Silva; Brito, Janaina de Oliveira; da Silva, Roberta F.; Monteiro, Henrique L.; Llesuy, Susana; De Angelis, Kátia; Amaral, Sandra L.; Zago, Anderson S.

    2017-01-01

    The purpose of this study was to compare the association between anti and pro-oxidant activity, nitrite concentration, and blood pressure (BP) in middle-aged and older women with different levels of estimated training status (TS). The sample consisted of 155 females (50–84 years) who were submitted to a physical examination to evaluate estimated TS through the “Functional Fitness Battery Test,” BP measurements, and plasma blood samples to evaluate pro-oxidant and antioxidant activity and nitrite concentrations. Participants were separated by age into a middle-aged group (<65 years) and an older (≥65 years) group and then subdivided in each group according to TS. Blood biochemistry was similar between groups. On the other hand, protein oxidation was lower in participants with higher TS, independent of age. Older females with higher TS presented higher nitrite concentrations, lower lipoperoxidation, and lower values of BP compared with those with lower TS. Lower GPx activity was observed in participants with higher TS compared with middle-aged with lower TS. Thus, our results suggest that good levels of TS may be associated with lower oxidative stress and higher nitrite concentration and may contribute to maintain normal or reduced blood pressure values. PMID:28326041

  10. Caustic-Side Solvent Extraction: Anti-Caking Surfactants Found to be Cause of Apparent Effect of High Nitrite Concentration on Cesium Stripping

    Energy Technology Data Exchange (ETDEWEB)

    Delmau, L.H.

    2002-06-13

    Experiments conducted in FY01 previously indicated a potential cesium stripping problem in the CSSX process due to the presence of nitrite in the waste simulant. The stripping issue seemed all the more important as the nitrite concentration increased. Experiments presented in this work have demonstrated that the true reason for the cesium stripping problem was in fact the presence of an anti-caking agent in the,sodium nitrite. used for the preparation of the simulants. The anti-caking agent is actually a mixture of well-known surfactants, sodium mono- and di-methyl naphthalene sulfonate that can partition into the organic-phase on extraction, then retain cesium upon stripping. The effect was demonstrated by adding known amounts of the anti-caking agent to clean systems. Data suggest that rejuvenation of the solvent can be obtained by a caustic wash following the stripping stage.

  11. Stress reaction in crayfish: chlorides help to withstand stress in high nitrite concentration conditions – preliminary study

    Directory of Open Access Journals (Sweden)

    Kozák P.

    2011-06-01

    Full Text Available A non-invasive method of recording cardiac activity (heart rate – HR and stress reaction (stress index – SI was used to understand the immediate and ongoing stress reaction of crayfish to the chemical stimuli. This method detects changes in the shape and amplitude parameters of the response to the stress factors, which characterized the crayfish functional state. Experimental animals (Astacus leptodactylus were divided to the two groups with (400 mg·L-1 Cl− and without added chlorides and then exposed to a stepwise increased level of nitrite to the final (sublethal-lethal concentration of 60 mg·L-1 N-NO\\hbox{$_{2}^{-}$}−2 within 24 hours. The course of crayfish reaction was evident and provided information about their reaction to the sublethal-lethal concentration over time. As expected, a less prominent stress reaction was detected in the group with chlorides. The non-invasive method successfully evaluated the sensing of chemical stimuli in water through HR and SI changes.

  12. [Nitrates and nitrites in meat products--nitrosamines precursors].

    Science.gov (United States)

    Avasilcăi, Liliana; Cuciureanu, Rodica

    2011-01-01

    To determine the content in nitrates and nitrites and the formation of two nitrosamines (N-nitrosodimethylamine--NDMA, and N-nitrosodiethylaamine--NDEA) in samples of chicken ham, dry Banat salami, dry French salami, traditional Romania sausages, and pork pastrami. Nitrites were determined by spectrophotometry with Peter-Griess reagent, and nitrates by the same method after reduction to nitrites with cadmium powder. High performance liquid chromatography with UV detection was used to determine nitrosamines. The initial concentration of nitrates, nitrites, NDMA and NDEA in the samples ranged as follows: 14.10-60.40 mg NO3/kg, 2.70-26.70 mg NO2/kg, from non-detectable to 0.90 microg NDMA/kg, and from non-detectable to 0.27 microg NDEA/kg, respectively. After 28 days the concentrations were: 3.24-17.1 mg NO3/kg, 0.04 -1.87 mg NO2/kg, 0.8-29 microg NDMA/kg, and 11.6-61.9 microg NDEA/kg, respectively. The decreased nitrate and nitrite and increased NDMA and NDEA concentrations prove that in food products nitrosamines are formed due to residual nitrite during their preservation. The determination of nitrasamines revealed levels much above the admitted maximal concentration for these food products.

  13. Biogenic amine formation and nitrite reactions in meat batter as affected by high-pressure processing and chilled storage.

    Science.gov (United States)

    Ruiz-Capillas, C; Aller-Guiote, P; Carballo, J; Colmenero, F Jiménez

    2006-12-27

    Changes in biogenic amine formation and nitrite depletion in meat batters as affected by pressure-temperature combinations (300 MPa/30 min/7, 20, and 40 degrees C), cooking process (70 degrees C/30 min), and storage (54 days/2 degrees C) were studied. Changes in residual nitrite concentration in raw meat batters were conditioned by the temperature and not by the pressure applied. Cooking process decreased (P nitrite concentration in all samples. High-pressure processing and cooking treatment increased (P nitrite concentration decreased with pressure processing, no effect was observed with the heating process of meat batters. High-pressure processing conditions had no effect on the rate of residual nitrite loss throughout the storage. The application of high pressure decreased (P processing conditions, generally, throughout storage biogenic amine levels did not change or increased, although quantitatively this effect was not very important.

  14. Nitrogen concentration profiles in oxy-nitrited high-speed steel

    International Nuclear Information System (INIS)

    Barcz, A.; Turos, A.; Wielunski, L.

    1976-01-01

    Nuclear microanalysis has been applied for the determination of in-depth concentration profiles of nitrogen in oxy-nitrided high-speed steel. The concentration profiles were deduced from measurements of the nitrogen content, determined by means of the 14 N(d,α) 12 C reaction for the set of initially identical samples after the removal of surface layers of sequentially increasing thicknesses. The 1.2 MeV deuterons were obtained from the Institute of Nuclear Research Van de Graaf accelerator LECH. The α-particles produced in the 14 N(d,α) 12 C reaction were detected by means of silicon surface barrier detector mounted at 150 deg C. Strong blocking of the nitrogen diffusion due to the presence of oxygen has been observed. The accuracy of nitrogen detection is of the order of 5% for nitrogen-rich regions and 10% for the matrix. However, the local non-uniformity of the steel may cause a spread of about 20% of the measured values. (T.G.)

  15. Effects of plant polyphenols and a-tocopherol on lipid oxidation, residual nitrites, biogenic amines, and N-nitrosamines formation during ripening and storage of dry-cured bacon

    Science.gov (United States)

    Effects of plant polyphenols (green tea polyphenols (GTP) and grape seed extract (GSE) and a-tocopherol on physicochemical parameters, lipid oxidation, residual nitrite, microbiological counts, biogenic amines, and N-nitrosamines were determined in bacons during dry-curing and storage. Results show ...

  16. Nitrite-dependent vasodilation is facilitated by hypoxia and is independent of known NO-generating nitrite reductase activities

    DEFF Research Database (Denmark)

    Fago, Angela; Dalsgaard, Thomas; Fago, Angela

    2007-01-01

    is largely intrinsic to the vessel and that under hypoxia physiological nitrite concentrations are sufficient to induce NO-mediated vasodilation independently of the nitrite reductase activities investigated here. Possible reaction mechanisms for nitrite vasoactivity, including formation of S...

  17. Effect of Thyme and Rosemary on The Quality Characteristics, Shelf-life, and Residual Nitrite Content of Sausages During Cold Storage

    Science.gov (United States)

    Jin, Sang Keun; Choi, Jung Seok; Lee, Seung Jae

    2016-01-01

    The effects of thyme and rosemary on the quality characteristics of sausages during cold storage were investigated. Sausages were prepared with thyme and rosemary powder (1 and 2%) and stored for 6 weeks at 10℃. The pH was significantly decreased in sausages by addition of thyme and rosemary compared to that observed in the control before and after storage. At 4 weeks of storage, the residual nitrite content was decreased by thyme and rosemary compared to the control. Lightness (L*) and yellowness (b*) were increased during storage, whereas redness (a*) and whiteness (W) were decreased before and after storage by addition of thyme and rosemary. The amount of TPC and lactic acid bacteria was lower at the end of storage in sausage containing thyme and rosemary. The 2, 2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical scavenging capacity of sausages was increased by addition of thyme and rosemary compared to that in the control before and after storage. In particular, T2 (0.2% thyme addition) showed the highest DPPH radical scavenging capacity during storage. In a sensory evaluation, flavor and overall acceptability were lower in sausages containing thyme and rosemary than in the control. However, at the end of storage (6 wk), aroma, flavor and overall acceptability were not significantly different among the sausage samples. PMID:27857542

  18. Serum concentrations of nitrite and malondialdehyde as markers of oxidative stress in chronic myeloid leukemia patients treated with tyrosine kinase inhibitors

    Directory of Open Access Journals (Sweden)

    Maria Juracy Petrola

    2012-01-01

    Full Text Available BACKGROUND: Chronic myeloid leukemia is a neoplasm characterized by clonal expansion of hematopoietic progenitor cells resulting from the (9:22(q34,11 translocation. The tyrosine kinase abl fusion protein,the initial leukemogenic event in chronic myeloid leukemia, is constitutively activated thus inducing the production of reactive oxygen species. Of particular relevance is the fact that an increase in reactive oxygen species can facilitate genomic instability and may contribute to disease progression. OBJETIVE: To evaluate oxidative stress by determining the levels of malondialdehyde and nitrite in chronic myeloid leukemia patients under treatment with 1st and 2nd generation tyrosine kinase inhibitors monitored at a referral hospital in Fortaleza, Ceará. METHODS: A cross-sectional study was performed of 64 male and female adults. Patients were stratified according to treatment. The levels of malondialdehyde and nitrite were determined by spectrophotometry. Statistical differences between groups were observed using the Student t-test and Fisher's exact test. The results are expressed as mean ± standard error of mean. The significance level was set for a p-value < 0.05 in all analyses. RESULTS: The results show significantly higher mean concentrations of nitrite and malondialdehyde in chronic myeloid leukemia patients using second-generation tyrosine kinase inhibitors compared to patients on imatinib. Conclusion: It follows that chronic myeloid leukemia patients present higher oxidative activity and that the increases in oxidative damage markers can indicate resistance to 1st generation tyrosine kinase inhibitors.

  19. Dependence of nitrite oxidation on nitrite and oxygen in low-oxygen seawater

    Science.gov (United States)

    Sun, Xin; Ji, Qixing; Jayakumar, Amal; Ward, Bess B.

    2017-08-01

    Nitrite oxidation is an essential step in transformations of fixed nitrogen. The physiology of nitrite oxidizing bacteria (NOB) implies that the rates of nitrite oxidation should be controlled by concentration of their substrate, nitrite, and the terminal electron acceptor, oxygen. The sensitivities of nitrite oxidation to oxygen and nitrite concentrations were investigated using 15N tracer incubations in the Eastern Tropical North Pacific. Nitrite stimulated nitrite oxidation under low in situ nitrite conditions, following Michaelis-Menten kinetics, indicating that nitrite was the limiting substrate. The nitrite half-saturation constant (Ks = 0.254 ± 0.161 μM) was 1-3 orders of magnitude lower than in cultivated NOB, indicating higher affinity of marine NOB for nitrite. The highest rates of nitrite oxidation were measured in the oxygen depleted zone (ODZ), and were partially inhibited by additions of oxygen. This oxygen sensitivity suggests that ODZ specialist NOB, adapted to low-oxygen conditions, are responsible for apparently anaerobic nitrite oxidation.

  20. Determination of the Minimum Inhibitory Concentration of the Barberry Extract and the Dried Residue of Red Grape and Their Effects on the Growth Inhibition of Sausage Bacteria by Using Response Surface Methodology (RSM

    Directory of Open Access Journals (Sweden)

    Fatemeh Riazi

    2015-09-01

    Full Text Available Background and Objectives: With regard to the hazards of nitrite, application of natural preservatives in order to reduce the microbial load of meat and meat products is increasing. Owing to their anti-bacterial properties, red barberry and the dried residue of red grape could be suitable replacers for nitrite. Materials and Methods: Agar dilution method was employed in order to determine the minimum inhibitory concentration (MIC of the barberry extract and the dried residue of red grape. The anti-microbial effects of the barberry extract (0-600 mg/kg, the dried residue of red grape (0-2% and nitrite (30-90 mg/kg were investigated on the total viable counts of Clostridium perfringens, as well as on the psychrophilic bacteria after 30 days of storage at 4°C. Finally, the effects of the three independent variables in the optimal sample were examined on the growth of the inoculated C. perfringens. Results: The MIC of the barberry extract and the dried residue of red grape on Staphylococcus aureus was 3 and 6 (mg/ml, respectively. In the case of Escherichia coli, it was 4 and 7 (mg/ml, respectively. The barberry extract and nitrite reduced the growth of the living aerobic bacteria significantly. The spores of the inoculated C. perfringens had no growth in the optimum sample during storage. Conclusions: The barberry extract and the dried residue of red grape as natural preservatives, could partially substitute for nitrite in order to reduce the microbial load of sausage.

  1. Hepatopulmonary syndrome induced by common bile duct ligation in a rabbit model: correlation between pulmonary vascular dilatation on thin-section CT and angiography and serum nitrite concentration or endothelial nitric oxide synthase (eNOS)1 expression

    International Nuclear Information System (INIS)

    Lee, Ki Nam; Yoon, Seong Kuk; Lee, Jin Wha; Kim, Ki Nam; Park, Byung Ho; Kwak, Jong Young; Jeong, Jin Sook; Kim, Young Hoon

    2004-01-01

    To investigate the correlation between radiologic vascular dilatation and serum nitrite concentration and eNOS expression in the endothelial cell and pneumocyte in a rabbit model of hepatopulmonary syndrome induced by common bile duct ligation (CBDL). Thin-section CT scans of the lung and pulmonary angiography were obtained 3 weeks after CBDL (n=6), or a sham operation (n=4), and intrapulmonary vasodilatation was assessed. The diameter and tortuosity of peripheral vessels in the right lower lobe by thin-section CT and angiography at the same level of the right lower lobe in all subjects were correlated to serum nitrite concentration and eNOS (endothelial nitric oxide synthase) expression as determined by immunostaining. The diameters of pulmonary vessels on thin-section CT were well correlated with nitrite concentrations in serum (r=0.92, ρ < 0.001). Dilated pulmonary vessels were significantly correlated with an increased eNOS expression (r=0.94, ρ < 0.0001), and the severity of pulmonary vessel tortuosity was found to be well correlated with serum nitrite concentration (r=0.90, ρ < 0.001). The peripheral pulmonary vasculature in hepatopulmonary syndrome induced by CBLD was dilated on thin-section CT and on angiographs. Our findings suggest that peripheral pulmonary vascular dilatations are correlated with serum nitrite concentrations and pulmonary eNOS expression

  2. Effect of Electrolytes on the Adsorption of Nitrite and Nitrate from ...

    African Journals Online (AJOL)

    Michael Horsfall

    presence of alkaline salts (Na3PO4, CH3COONa; 95.5 per cent) and neutral chloride salts (NaCl, MgCl2; 90.4 per cent) compared to ... The charcoal was freed off its residual nitrite and ..... separation factor, Rl, over the test concentrations have.

  3. Influence of training status and eNOS haplotypes on plasma nitrite concentrations in normotensive older adults: a hypothesis-generating study.

    Science.gov (United States)

    da Silva, Roberta Fernanda; Sertório, Jonas Tadeu Cau; Lacchini, Riccardo; Trapé, Atila Alexandre; Tanus-Santos, José Eduardo; Rush, James W E; Amaral, Sandra Lia; Zago, Anderson Saranz

    2014-12-01

    The purpose of this study was to evaluate the relationship between 3 eNOS gene polymorphisms and training status (TS) in affecting plasma nitrite concentration (NO2) in normotensive adults over 50 years old. Resting blood pressure (BP) was measured in all participants (n = 101). Plasma was taken to analyze: lipid profile, nitrite concentration (NO2) and lipid peroxide levels (T-BARS). Also, genomic DNA was extracted from plasma for genotyping NOS3 polymorphisms (-786T>C; 894G>T; and VNTR in intron 4). TS was determined by one-mile walk test and Functional Fitness Test Battery from AAHPERD (TS1-regular TS; TS2-good TS; and TS3-very good TS). BP was not influenced by TS, but NO2 was 15% higher in TS3 (123 ± 27 nM) compared to TS-2 (106 ± 22 nM). No differences were found in plasma NO2 in the haplotype analyses. However, the presence of the C allele (T-786C) and ASP allele (Glu298Asp) was found to enhance the correlation between TS and NO2 levels (r = 0.492 in C/4b/ASP haplotype and r = 0.855 in C/4a/ASP haplotype). This study thus identifies NOS3 polymorphism-dependent sensitivity to the effects of physical training on plasma NO2. Maintenance of good levels of training status, in carriers of C allele for T-786C polymorphism, combined with ASP allele for Glu298Asp polymorphism, may result in an increase in the NO2 plasma concentrations, which may reflect improved NO bioavailability in older adult normotensive individuals.

  4. The correlation of nitrite concentration with lesion size in initial phase of stroke; It is not correlated with National Institute Health Stroke Scale

    Directory of Open Access Journals (Sweden)

    Mehdi Nematbakhsh

    2008-06-01

    Full Text Available

    • BACKGROUND: The role of Nitric Oxide (NO and its metabolites in stroke has been examined clinically and experimentally. The relationship between plasma NO level and Lesion Size (LS or clinical severity of stroke is still under investigation. In this clinical study, the serum level of Nitrite (NI; the last metabolite of NO was measured in first and fifth days of onset of the stroke, and its correlation with LS was determined.
    • METHOD: 37 Cerebrovascular Attack (CVA patients were considered. The National Institute Health Stroke Scale (NIHSS was assessed to determined neurological impairment within 24 hours of onset. On the basis of NIHSS, the patients were divided into mild, moderate and severe groups. CT Scan for all patients were obtained in the first day, and based on CT Scan results, the patients were also divided into hemorrhagic, ischemic and normal groups. The serum level of NI and the LS were determined.
    • RESULTS: The mean serum levels of NI in 37 patients in the first and fifth days of stroke were 8.43± 1.23 and 7.46±0.72 7mole/liter with no significance difference. The analyses of data indicated no significant correlation between NI concentration and NIHSS, but in patients with abnormal CT Scan, statistical correlation was existed between NI concentration and LS (r=0.521, p=0.022.
    • CONCLUSION: The NI concentration is not correlated with NIHSS, but it is correlated with LS. The sources of NO metabolite sources are different; neuronal, endothelial or inducible. Therefore the concentration of NO or NI is not exactly the endothelial NO reprehensive which is beneficial in stroke, and it seems that the relationship between NO precursor subtypes and NIHSS or LS is needed to investigate.
    • KEYWORDS: Nitric Oxide, Stroke

  5. Biogas from Agricultural Residues as Energy Source in Hybrid Concentrated Solar Power

    NARCIS (Netherlands)

    Corré, W.J.; Conijn, J.G.

    2016-01-01

    This paper explores the possibilities of sustainable biogas use for hybridisation of Concentrated Solar Power (HCSP) in Europe. The optimal system for the use of biogas from agricultural residues (manure and crop residues) in HCSP involves anaerobic digestion with upgrading of biogas to

  6. Outcompeting nitrite-oxidizing bacteria in single-stage nitrogen removal in sewage treatment plants: a model-based study.

    Science.gov (United States)

    Pérez, Julio; Lotti, Tommaso; Kleerebezem, Robbert; Picioreanu, Cristian; van Loosdrecht, Mark C M

    2014-12-01

    This model-based study investigated the mechanisms and operational window for efficient repression of nitrite oxidizing bacteria (NOB) in an autotrophic nitrogen removal process. The operation of a continuous single-stage granular sludge process was simulated for nitrogen removal from pretreated sewage at 10 °C. The effects of the residual ammonium concentration were explicitly analyzed with the model. Competition for oxygen between ammonia-oxidizing bacteria (AOB) and NOB was found to be essential for NOB repression even when the suppression of nitrite oxidation is assisted by nitrite reduction by anammox (AMX). The nitrite half-saturation coefficient of NOB and AMX proved non-sensitive for the model output. The maximum specific growth rate of AMX bacteria proved a sensitive process parameter, because higher rates would provide a competitive advantage for AMX. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Platelet inhibition by nitrite is dependent on erythrocytes and deoxygenation.

    Directory of Open Access Journals (Sweden)

    Sirada Srihirun

    Full Text Available Nitrite is a nitric oxide (NO metabolite in tissues and blood, which can be converted to NO under hypoxia to facilitate tissue perfusion. Although nitrite is known to cause vasodilation following its reduction to NO, the effect of nitrite on platelet activity remains unclear. In this study, the effect of nitrite and nitrite+erythrocytes, with and without deoxygenation, on platelet activity was investigated.Platelet aggregation was studied in platelet-rich plasma (PRP and PRP+erythrocytes by turbidimetric and impedance aggregometry, respectively. In PRP, DEANONOate inhibited platelet aggregation induced by ADP while nitrite had no effect on platelets. In PRP+erythrocytes, the inhibitory effect of DEANONOate on platelets decreased whereas nitrite at physiologic concentration (0.1 µM inhibited platelet aggregation and ATP release. The effect of nitrite+erythrocytes on platelets was abrogated by C-PTIO (a membrane-impermeable NO scavenger, suggesting an NO-mediated action. Furthermore, deoxygenation enhanced the effect of nitrite as observed from a decrease of P-selectin expression and increase of the cGMP levels in platelets. The ADP-induced platelet aggregation in whole blood showed inverse correlations with the nitrite levels in whole blood and erythrocytes.Nitrite alone at physiological levels has no effect on platelets in plasma. Nitrite in the presence of erythrocytes inhibits platelets through its reduction to NO, which is promoted by deoxygenation. Nitrite may have role in modulating platelet activity in the circulation, especially during hypoxia.

  8. Determination of potassium concentration in salt water for residual beta radioactivity measurements

    International Nuclear Information System (INIS)

    Suarez-Navarro, J.A.; Pujol, Ll.

    2004-01-01

    High interferences may arise in the determination of potassium concentration in salt water. Several analytical methods were studied to determine which method provided the most accurate measurements of potassium concentration. This study is relevant for radiation protection because the exact amount of potassium in water samples must be known for determinations of residual beta activity concentration. The fitting algorithm of the calibration curve and estimation of uncertainty in potassium determinations were also studied. The reproducibility of the proposed analytical method was tested by internal and external validation. Furthermore, the residual beta activity concentration of several Spanish seawater and brackish river water samples was determined using the proposed method

  9. Incubation of curing brines for the production of ready-to-eat, uncured, no-nitrite-or-nitrate-added, ground, cooked and sliced ham.

    Science.gov (United States)

    Krause, B L; Sebranek, J G; Rust, R E; Mendonca, A

    2011-12-01

    Salt concentration, vegetable juice powder (VJP) concentration and temperature were investigated to determine necessary conditions for incubation of curing brines including VJP and a starter culture containing Staphylococcus carnosus prior to production of naturally cured, no-nitrate/nitrite-added meat products. Subsequently, incubated brines were utilized to produce no-nitrate/nitrite-added sliced ham in which quality characteristics and residual nitrite concentrations were measured to determine feasibility of brine incubation for nitrate conversion prior to injection. Two ham treatments (one with VJP and starter culture; one with pre-converted VJP) and a nitrite-added control were used. No differences (P>0.05) were found for color in the VJP treatments. Control sliced ham was redder after 42 days of storage, retaining significantly (Phams during the first week of storage. While the nitrite-added control retained greater red color and initially had more residual nitrite than the VJP treatments, the two VJP treatments did not differ from each other. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. Endogenous levels of nitrites and nitrates in wide consumption foodstuffs: Results of five years of official controls and monitoring.

    Science.gov (United States)

    Iammarino, Marco; Di Taranto, Aurelia; Cristino, Marianna

    2013-10-15

    The massive introduction of nitrogen fertilisers, necessary to maximise the global food production, has brought about an increase of the residual amounts of nitrites and nitrates in the products. Notoriously, these compounds may exercise toxic effects. In this work the results obtained from 5years of official controls and monitoring focused on tracing quantifiable amounts of nitrites and nitrates in 1785 samples of meat, dairy, fish products and leafy vegetables are reported. A widespread presence of nitrates at low concentrations in foodstuffs was verified. High concentrations of nitrates were registered in some leafy vegetables and mussels samples, while high nitrites concentrations were registered in some spinach samples. The results confirmed the necessity to develop most controls and suggest the introduction of new legal limits related to some combinations contaminant/matrix. Such new limits may fill legislative gaps that may cause wrong interpretations of the results obtained during official controls. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Fluorometric determination of nitrite with 4-hydroxycoumarin

    Energy Technology Data Exchange (ETDEWEB)

    Ohta, T.; Arai, Y.; Takitani, S.

    1986-12-01

    A simple, sensitive, and reproducible fluorometric method for determination of nitrite has been developed. This method is based on the nitrosation of 4-hydroxycoumarin in acidic medium and subsequent reduction to 3-amino-4-hydroxy-coumarin, which is fluorescent in alkaline medium. The fluorescence intensity is proportional to the nitrite concentration in the range of 3 ng/mL to 1 ..mu..g/mL in the sample solution, with a relative standard deviation of 0.5% (50 ng/mL). The method has been applied to the determination of nitrite in saliva.

  12. Study on the pelletizing of sulfate residue with magnetite concentrate in grate-kiln system

    Directory of Open Access Journals (Sweden)

    Shufeng Y.

    2010-01-01

    Full Text Available The experiment on the feasibility of pelletizing with magnetite concentrate and the wasted sulfate residue was carried out, to research the performance of pellet in grate-kiln system and simulate the grate-kiln pelletizing process in the micro-pellet roasting simulation system in laboratory, and the process experiments on preheating and roasting sections were conducted. The results show that in order to obtain pellet with good performance and the magnetite concentrate should be over 20 in mass percent, the suitable pelletizing time is about 10 min and moisture is around 12.5%. Also, according to the process parameters of drying and preheating sections obtained from experiment, it will be successful to use magnetite concentrate and the wasted sulfate residue for pelletizing, which exploits a new way for the use of sulfate residue.

  13. Quantifying the sources and sinks of nitrite in the oxygen minimum zone of the Eastern Tropical South Pacific

    Science.gov (United States)

    Ji, Qixing; Widner, Brittany; Jayakumar, Amal; Ward, Bess; Mulholland, Margaret

    2017-04-01

    In coastal upwelling regions, high surface productivity leads to high export and intense remineralization consuming oxygen. This, in combination with slow ventilation, creates oxygen minimum zones (OMZ) in eastern boundary regions of the ocean, such as the one off the Peruvian coast in the Eastern Tropical South Pacific. The OMZ is characterized by a layer of high nitrite concentration coinciding with water column anoxia. Sharp oxygen gradients are located above and below the anoxic layer (upper and lower oxyclines). Thus, the OMZ harbors diverse microbial metabolisms, several of which involve the production and consumption of nitrite. The sources of nitrite are ammonium oxidation and nitrate reduction. The sinks of nitrite include anaerobic ammonium oxidation (anammox), canonical denitrification and nitrite oxidation to nitrate. To quantify the sources and sinks of nitrite in the Peruvian OMZ, incubation experiments with 15N-labeled substrates (ammonium, nitrite and nitrate) were conducted on a research cruise in January 2015. The direct measurements of instantaneous nitrite production and consumption rates were compared with ambient nitrite concentrations to evaluate the turnover rate of nitrite in the OMZ. The distribution of nitrite in the water column showed a two-peak structure. A primary nitrite maximum (up to 0.5 μM) was located in the upper oxycline. A secondary nitrite maximum (up to 10 μM) was found in the anoxic layer. A nitrite concentration minimum occurred at the oxic-anoxic interface just below the upper oxycline. For the sources of nitrite, highest rates of ammonium oxidation and nitrate reduction were detected in the upper oxycline, where both nitrite and oxygen concentrations were low. Lower rates of nitrite production were detected within the layer of secondary nitrite maximum. For the sinks of nitrite, the rates of anammox, denitrification and nitrite oxidation were the highest just below the oxic-anoxic interface. Low nitrite consumption

  14. Differential uptake and metabolism of nitrite in normoxic and hypoxic goldfish

    DEFF Research Database (Denmark)

    Jensen, Frank Bo; Hansen, Marie N.

    2011-01-01

    extracellular and intracellular compartments, revealing nitrosative stress with extensive nitros(yl)ation of thiols, amines and heme groups. The degree of nitrosative stress correlated with nitrite load. Nitrate levels increased in all compartments, reflecting that a significant fraction of the nitrite taken up...... was converted to non-toxic nitrate. The generation of methemoglobin and nitrosylhemoglobin (assessed by spectral deconvolution) was more pronounced during normoxic nitrite exposure than during hypoxic nitrite exposure, in agreement with the higher nitrite load in normoxic fish. However, at any given nitrite......Nitrite is a physiological important nitric oxide donor at low concentrations but becomes toxic at high concentrations, as develops in freshwater fish exposed to environmental nitrite. We hypothesized that nitrite uptake across the gills differs between normoxic and hypoxic fish and that nitrite...

  15. 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.

  16. Time-dependent depletion of nitrite in pork/beef and chicken meat products and its effect on nitrite intake estimation

    Science.gov (United States)

    Merino, Leonardo; Darnerud, Per Ola; Toldrá, Fidel; Ilbäck, Nils-Gunnar

    2016-01-01

    ABSTRACT The food additive nitrite (E249, E250) is commonly used in meat curing as a food preservation method. Because of potential negative health effects of nitrite, its use is strictly regulated. In an earlier study we have shown that the calculated intake of nitrite in children can exceed the acceptable daily intake (ADI) when conversion from dietary nitrate to nitrite is included. This study examined time-dependent changes in nitrite levels in four Swedish meat products frequently eaten by children: pork/beef sausage, liver paté and two types of chicken sausage, and how the production process, storage and also boiling (e.g., simmering in salted water) and frying affect the initial added nitrite level. The results showed a steep decrease in nitrite level between the point of addition to the product and the first sampling of the product 24 h later. After this time, residual nitrite levels continued to decrease, but much more slowly, until the recommended use-by date. Interestingly, this continuing decrease in nitrite was much smaller in the chicken products than in the pork/beef products. In a pilot study on pork/beef sausage, we found no effects of boiling on residual nitrite levels, but frying decreased nitrite levels by 50%. In scenarios of time-dependent depletion of nitrite using the data obtained for sausages to represent all cured meat products and including conversion from dietary nitrate, calculated nitrite intake in 4-year-old children generally exceeded the ADI. Moreover, the actual intake of nitrite from cured meat is dependent on the type of meat source, with a higher residual nitrite levels in chicken products compared with pork/beef products. This may result in increased nitrite exposure among consumers shifting their consumption pattern of processed meats from red to white meat products. PMID:26743589

  17. Monitoring of nitrites and nitrates levels in leafy vegetables (spinach and lettuce): a contribution to risk assessment.

    Science.gov (United States)

    Iammarino, Marco; Di Taranto, Aurelia; Cristino, Marianna

    2014-03-15

    Nitrites and nitrates are compounds considered harmful to humans and the major part of the daily intake of nitrates in foodstuffs is related to vegetable consumption. In this work, 150 leafy vegetables samples (75 spinach and 75 lettuce) were analysed in order to assess the levels of nitrites and nitrates. The analyses were carried out by a validated ion chromatography method and the samples with nitrate concentrations higher than legal limits and/or with quantifiable concentrations of nitrites were confirmed by an alternative ion chromatography method. Nitrate levels higher than legal limits were detected both in spinach (four samples) and in lettuce (five samples). Nitrite residues were registered both at low concentrations--lower than 28.5 mg kg⁻¹ (12 spinach samples)--and at high concentrations, up to 197.5 mg kg⁻¹ (three spinach and one lettuce sample). Considering the non-negligible percentage of 'not-compliant' samples for nitrates (6.0%), control is needed. Moreover, it is possible to suggest the introduction in the Communities Regulations of a 'maximum admissible level' for nitrites in leafy vegetables. © 2013 Society of Chemical Industry.

  18. The Effect of Kaffir Lime Leaves Distillation Residue Oleoresin Concentration on Active Paper Packaging Characteristics

    Science.gov (United States)

    Kawiji; Utami, R.; Ulum, S.; Khasanah, L. U.; Manuhara, G. J.; Atmaka, W.

    2018-03-01

    Oleoresin of kaffir lime leaves distillation residue still contains some active compounds such as Citronellal, β-Citronellol, and Linalool which potential to incorporated on the active paper packaging. The purposes of this study were to determine the effect of kaffir lime leaves distillation residue oleoresin concentration on the physical characteristics, sensory characteristics, and antimicrobial activity of the active paper packaging incorporated with kaffir lime leaves distillation residue oleoresin and to determine the functional groups of active paper packaging. The concentration of kaffir lime leaves distillation residue oleoresin were varied at 0%, 2%, 4% and 6%. The result showed that the addition of kaffir lime leaves distillation residue oleoresin increased the thickness and moisture content of the paper and decreased the tensile strengths and folding endurances of active paper packaging. The microbial inhibition tends to increase along with the higher oleoresin concentration addition. Aromatic CH group were found at a wavelength of 897.90 cm-1 of on paper packaging with 2% oleoresin indicated as functional aromatic functional group allegedly obtained from the kaffir lime leaves oleoresin.

  19. Modification of membrane sulfhydryl groups in bacteriostatic action of nitrite

    International Nuclear Information System (INIS)

    Buchman, G.W. III; Hansen, J.N.

    1987-01-01

    The mechanism by which nitrite inhibits outgrowing spores of bacillus cereus T was examined by using techniques developed earlier for nitrite analogs. The morphological stage of inhibition, cooperativity effects, effect of pH on inhibition, kinetics of protection against tritiated iodoacetate incorporation into membrane sulfhydryl groups, and protection against the bacteriocidal effect of carboxymethylation of iodoacetate indicate that nitrite acts as a membrane-directed sulfhydryl agent. The mechanism by which nitrite modifies the chemical reactivity of the sulfhyrdyl group could be either direct covalent modification or inactivation through communication with another modified membrane component. Profiles of pH effects suggest that the active agent is the protonated form of nitrite. The nitrite concentrations which modify membrane sulfhydryl activity coincide with those which have a bacteriostatic effect. These results are consistent with membrane sulfhydryl modification as a component of the mechanism of nitrite-induced bacteriostasis in this aerobic sporeformer

  20. Mutagenesis breeding research of Lactobacillus brevis of nitrite reduction

    Directory of Open Access Journals (Sweden)

    LI Zeli

    2015-10-01

    Full Text Available The pollution of nitrite in food became one of the focus of food safety issues,the use of biotechnology methods degrading nitrite became hotspot.The primitive strain was Lactobacillus brevis C2,preserved in our laboratory,had the ability to degrade nitrite,through composite mutagenesis of 15 W,254 nm,20 cm ultraviolet mutagenesis (UV for 120 s and 0.8% diethyl sulfate(DES in 37℃ mutation for 40 min,after screening,we successfully obtained high efficient strain of nitrite degradation,named UV6-DS2,relative to the starting strain,under the condition of 400 mg/L nitrite,after 12 h degradation,nitrite degradation rate increased from 92.8% to 97.8%,to explore its application in food was able to effectively reduce concentration of nitrite in food.

  1. Nitrate decreases xanthine oxidoreductase-mediated nitrite reductase activity and attenuates vascular and blood pressure responses to nitrite.

    Science.gov (United States)

    Damacena-Angelis, Célio; Oliveira-Paula, Gustavo H; Pinheiro, Lucas C; Crevelin, Eduardo J; Portella, Rafael L; Moraes, Luiz Alberto B; Tanus-Santos, Jose E

    2017-08-01

    Nitrite and nitrate restore deficient endogenous nitric oxide (NO) production as they are converted back to NO, and therefore complement the classic enzymatic NO synthesis. Circulating nitrate and nitrite must cross membrane barriers to produce their effects and increased nitrate concentrations may attenuate the nitrite influx into cells, decreasing NO generation from nitrite. Moreover, xanthine oxidoreductase (XOR) mediates NO formation from nitrite and nitrate. However, no study has examined whether nitrate attenuates XOR-mediated NO generation from nitrite. We hypothesized that nitrate attenuates the vascular and blood pressure responses to nitrite either by interfering with nitrite influx into vascular tissue, or by competing with nitrite for XOR, thus inhibiting XOR-mediated NO generation. We used two independent vascular function assays in rats (aortic ring preparations and isolated mesenteric arterial bed perfusion) to examine the effects of sodium nitrate on the concentration-dependent responses to sodium nitrite. Both assays showed that nitrate attenuated the vascular responses to nitrite. Conversely, the aortic responses to the NO donor DETANONOate were not affected by sodium nitrate. Further confirming these results, we found that nitrate attenuated the acute blood pressure lowering effects of increasing doses of nitrite infused intravenously in freely moving rats. The possibility that nitrate could compete with nitrite and decrease nitrite influx into cells was tested by measuring the accumulation of nitrogen-15-labeled nitrite ( 15 N-nitrite) by aortic rings using ultra-performance liquid chromatography tandem mass-spectrometry (UPLC-MS/MS). Nitrate exerted no effect on aortic accumulation of 15 N-nitrite. Next, we used chemiluminescence-based NO detection to examine whether nitrate attenuates XOR-mediated nitrite reductase activity. Nitrate significantly shifted the Michaelis Menten saturation curve to the right, with a 3-fold increase in the

  2. Separation of thorium (IV) from lanthanide concentrate (LC) and water leach purification (WLP) residue

    International Nuclear Information System (INIS)

    AL-Areqi, Wadeeah M.; Majid, Amran Ab.; Sarmani, Sukiman

    2014-01-01

    Thorium (IV) content in industrial residue produced from rare earth elements production industry is one of the challenges to Malaysian environment. Separation of thorium from the lanthanide concentrate (LC) and Water Leach Purification (WLP) residue from rare earth elements production plant is described. Both materials have been tested by sulphuric acid and alkaline digestions. Th concentrations in LC and WLP were determined to be 1289.7 ± 129 and 1952.9±17.6 ppm respectively. The results of separation show that the recovery of Th separation from rare earth in LC after concentrated sulphuric acid dissolution and reduction of acidity to precipitate Th was found 1.76-1.20% whereas Th recovery from WLP was less than 4% after concentrated acids and alkali digestion processes. Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS) was used to determine Th concentrations in aqueous phase during separation stages. This study indicated that thorium maybe exists in refractory and insoluble form which is difficult to separate by these processes and stays in WLP residue as naturally occurring radioactive material (NORM)

  3. The residual C concentration control for low temperature growth p-type GaN

    International Nuclear Information System (INIS)

    Liu Shuang-Tao; Zhao De-Gang; Yang Jing; Jiang De-Sheng; Liang Feng; Chen Ping; Zhu Jian-Jun; Liu Zong-Shun; Li Xiang; Liu Wei; Xing Yao; Zhang Li-Qun

    2017-01-01

    In this work, the influence of C concentration to the performance of low temperature growth p-GaN is studied. Through analyses, we have confirmed that the C impurity has a compensation effect to p-GaN. At the same time we have found that several growth and annealing parameters have influences on the residual C concentration: (i) the C concentration decreases with the increase of growth pressure; (ii) we have found there exists a Ga memory effect when changing the Cp 2 Mg flow which will lead the growth rate and C concentration increase along the increase of Cp 2 Mg flow; (iii) annealing outside of metal–organic chemical vapor deposition (MOCVD) could decrease the C concentration while in situ annealing in MOCVD has an immobilization role to C concentration. (paper)

  4. Uncertainty of pesticide residue concentration determined from ordinary and weighted linear regression curve.

    Science.gov (United States)

    Yolci Omeroglu, Perihan; Ambrus, Árpad; Boyacioglu, Dilek

    2018-03-28

    Determination of pesticide residues is based on calibration curves constructed for each batch of analysis. Calibration standard solutions are prepared from a known amount of reference material at different concentration levels covering the concentration range of the analyte in the analysed samples. In the scope of this study, the applicability of both ordinary linear and weighted linear regression (OLR and WLR) for pesticide residue analysis was investigated. We used 782 multipoint calibration curves obtained for 72 different analytical batches with high-pressure liquid chromatography equipped with an ultraviolet detector, and gas chromatography with electron capture, nitrogen phosphorus or mass spectrophotometer detectors. Quality criteria of the linear curves including regression coefficient, standard deviation of relative residuals and deviation of back calculated concentrations were calculated both for WLR and OLR methods. Moreover, the relative uncertainty of the predicted analyte concentration was estimated for both methods. It was concluded that calibration curve based on WLR complies with all the quality criteria set by international guidelines compared to those calculated with OLR. It means that all the data fit well with WLR for pesticide residue analysis. It was estimated that, regardless of the actual concentration range of the calibration, relative uncertainty at the lowest calibrated level ranged between 0.3% and 113.7% for OLR and between 0.2% and 22.1% for WLR. At or above 1/3 of the calibrated range, uncertainty of calibration curve ranged between 0.1% and 16.3% for OLR and 0% and 12.2% for WLR, and therefore, the two methods gave comparable results.

  5. Residual concentrations of micropollutants in benthic mussels in the coastal areas of Bohai Sea, North China

    International Nuclear Information System (INIS)

    Liu Wenxin; Chen Jianglin; Lin Xiumei; Fan Yongsheng; Tao Shu

    2007-01-01

    Studies of heavy metals and organic pollutants in different benthic mussel species from Bohai Sea show that concentrations of Cd in mussels commonly exceed national biological quality standards. In addition, a site located in Laizhou Bay exhibits higher average concentrations of As, Hg and Pb with respect to the other sites. Residual levels of petroleum hydrocarbons at several sites in Liaodong Bay also exceed quality guidelines. Contents and compositional characteristics of DDT and its metabolites in mussels suggest the probability of recent inputs and potential ecological risks to the local benthic environment. - Residual Cd contents of mussels at many sites in Bohai Sea exceed national marine biological quality standard and compositions of DDT metabolites indicate recent inputs and potential risk

  6. Estimation of the residual bromine concentration after disinfection of cooling water by statistical evaluation.

    Science.gov (United States)

    Megalopoulos, Fivos A; Ochsenkuehn-Petropoulou, Maria T

    2015-01-01

    A statistical model based on multiple linear regression is developed, to estimate the bromine residual that can be expected after the bromination of cooling water. Make-up water sampled from a power plant in the Greek territory was used for the creation of the various cooling water matrices under investigation. The amount of bromine fed to the circuit, as well as other important operational parameters such as concentration at the cooling tower, temperature, organic load and contact time are taken as the independent variables. It is found that the highest contribution to the model's predictive ability comes from cooling water's organic load concentration, followed by the amount of bromine fed to the circuit, the water's mean temperature, the duration of the bromination period and finally its conductivity. Comparison of the model results with the experimental data confirms its ability to predict residual bromine given specific bromination conditions.

  7. Predicting the concentration of residual methanol in industrial formalin using machine learning

    OpenAIRE

    Heidkamp, William

    2016-01-01

    In this thesis, a machine learning approach was used to develop a predictive model for residual methanol concentration in industrial formalin produced at the Akzo Nobel factory in Kristinehamn, Sweden. The MATLABTM computational environment supplemented with the Statistics and Machine LearningTM toolbox from the MathWorks were used to test various machine learning algorithms on the formalin production data from Akzo Nobel. As a result, the Gaussian Process Regression algorithm was found to pr...

  8. Researches concerning nitrates and nitrites accumulation in carrots, along of the vegetation stages

    Directory of Open Access Journals (Sweden)

    Monica NEGREA

    2008-05-01

    Full Text Available The presented paper deals with the determination of nitrates and nitrites content in carrots, in different vegetation stages of the carrot culture. High nitrates and nitrites concentration in vegetables is mainly due to excessive nitrogen content in the soil system, thus deteriorating the nutritional and hygienic values of products and complicating the processing and storage. The determination was tested on carrot samples assayed from an experimental field set up near Timisoara. In experimental field, to the carrot culture was administrated different doses of fertilizers (NPK and the samples for analysis were assayed in different phases of vegetation. The obtained results indicated that the highest level of nitrate in carrots was found to the variant b3 (N150P90K90 in experimental field, who was above maximum limit allowed (LMA. Maximum limit allowed for nitrates in carrots, in accordance with ORDER No. 293/640/2001-1/2002 regarding security and quality conditions for vegetables and fresh fruits for human consumption is 400 ppm. For all other samples of carrots the nitrates level was below of LMA. The nitrite content grows in case of fertilizer administration during the whole vegetation stages of the plant. In variant N150P90K90 the nitrite content was above (LMA in carrot samples in all stages of vegetation. The nitrite content in carrots should not exceed 1-2 ppm. Nitrate and nitrite content in carrots was done with the help of High Performance Liquid Chromatography (HPLC in the Laboratory for the Measurement of Residues of the Department of Agro-techniques of the U.S.A-V.M.B in Timisoara.

  9. Reactions of nitrite with hemoglobin measured by membrane inlet mass spectrometry

    Science.gov (United States)

    Tu, Chingkuang; Mikulski, Rose; Swenson, Erik R.; Silverman, David N.

    2010-01-01

    Membrane inlet mass spectrometry was used to observe nitric oxide in the well-studied reaction of nitrite with hemoglobin. The membrane inlet was submerged in the reaction solutions and measured NO in solution via its flux across a semipermeable membrane leading to the mass spectrometer detecting the mass-to-charge ratio m/z 30. This method measures NO directly in solution and is an alternate approach compared with methods that purge solutions to measure NO. Addition to deoxy-Hb(FeII) (near 38 µM heme concentration) of nitrite in a range of 80 µM to 16 mM showed no accumulation of either NO or N2O3 on a physiologically relevant time scale with a sensitivity near 1 nM. The addition of nitrite to oxy-Hb(FeII) and met-Hb(FeIII) did not accumulate free NO to appreciable extents. These observations show that for several minutes after mixing nitrite with hemoglogin, free NO does not accumulate to levels exceeding the equilibrium level of NO. The presence of cyanide ions did not alter the appearance of the data; however, the presence of 2 mM mercuric ions at the beginning of the experiment with deoxy-Hb(FeII) shortened the initial phase of NO accumulation and increased the maximal level of free, unbound NO by about twofold. These experiments appear consistent with no role of met-Hb(FeIII) in the generation of NO and an increase in nitrite reductase activity caused by the presumed binding of mercuric to cysteine residues. These results raise questions about the ability of reduction of nitrite mediated by deoxy-Hb(FeII) to play a role in vasodilation. PMID:18848984

  10. Nebulization of the acidified sodium nitrite formulation attenuates acute hypoxic pulmonary vasoconstriction

    Directory of Open Access Journals (Sweden)

    Surber Mark W

    2010-06-01

    Full Text Available Abstract Background Generalized hypoxic pulmonary vasoconstriction (HPV occurring during exposure to hypoxia is a detrimental process resulting in an increase in lung vascular resistance. Nebulization of sodium nitrite has been shown to inhibit HPV. The aim of this project was to investigate and compare the effects of nebulization of nitrite and different formulations of acidified sodium nitrite on acute HPV. Methods Ex vivo isolated rabbit lungs perfused with erythrocytes in Krebs-Henseleit buffer (adjusted to 10% hematocrit and in vivo anesthetized catheterized rabbits were challenged with periods of hypoxic ventilation alternating with periods of normoxic ventilation. After baseline hypoxic challenges, vehicle, sodium nitrite or acidified sodium nitrite was delivered via nebulization. In the ex vivo model, pulmonary arterial pressure and nitric oxide concentrations in exhaled gas were monitored. Nitrite and nitrite/nitrate were measured in samples of perfusion buffer. Pulmonary arterial pressure, systemic arterial pressure, cardiac output and blood gases were monitored in the in vivo model. Results In the ex vivo model, nitrite nebulization attenuated HPV and increased nitric oxide concentrations in exhaled gas and nitrite concentrations in the perfusate. The acidified forms of sodium nitrite induced higher levels of nitric oxide in exhaled gas and had longer vasodilating effects compared to nitrite alone. All nitrite formulations increased concentrations of circulating nitrite to the same degree. In the in vivo model, inhaled nitrite inhibited HPV, while pulmonary arterial pressure, cardiac output and blood gases were not affected. All nitrite formulations had similar potency to inhibit HPV. The tested concentration of appeared tolerable. Conclusion Nitrite alone and in acidified forms effectively and similarly attenuates HPV. However, acidified nitrite formulations induce a more pronounced increase in nitric oxide exhalation.

  11. Effect of Residue Nitrogen Concentration and Time Duration on Carbon Mineralization Rate of Alfalfa Residues in Regions with Different Climatic Conditions

    Directory of Open Access Journals (Sweden)

    saeid shafiei

    2017-08-01

    Full Text Available Introduction Various factors like climatic conditions, vegetation, soil properties, topography, time, plant residue quality and crop management strategies affect the decomposition rate of organic carbon (OC and its residence time in soil. Plant residue management concerns nutrients recycling, carbon recycling in ecosystems and the increasing CO2 concentration in the atmosphere. Plant residue decomposition is a fundamental process in recycling of organic matter and elements in most ecosystems. Soil management, particularly plant residue management, changes soil organic matter both qualitatively and quantitatively. Soil respiration and carbon loss are affected by soil temperature, soil moisture, air temperature, solar radiation and precipitation. In natural agro-ecosystems, residue contains different concentrations of nitrogen. It is important to understand the rate and processes involved in plant residue decomposition, as these residues continue to be added to the soil under different weather conditions, especially in arid and semi-arid climates. Material and methods Organic carbon mineralization of alfalfa residue with different nitrogen concentrations was assessed in different climatic conditions using split-plot experiments over time and the effects of climate was determined using composite analysis. The climatic conditions were classified as warm-arid (Jiroft, temperate arid (Narab and cold semi-arid (Sardouiyeh using cluster analysis and the nitrogen (N concentrations of alfalfa residue were low, medium and high. The alfalfa residue incubated for four different time periods (2, 4, 6 and 8 months. The dynamics of organic carbon in different regions measured using litter bags (20×10 cm containing 20 g alfalfa residue of 2-10 mm length which were placed on the soil surface. Results and discussion The results of this study showed that in a warm-arid (Jiroft, carbon loss and the carbon decomposition rate constant were low in a cold semi

  12. A method for assessing residual NAPL based on organic chemical concentrations in soil samples

    International Nuclear Information System (INIS)

    Feenstra, S.; Mackay, D.M.; Cherry, J.A.

    1991-01-01

    Ground water contamination by non-aqueous phase liquid (NAPL) chemicals is a serious concern at many industrial facilities and waste disposal sites. NAPL in the form of immobile residual contamination, or pools of mobile or potentially mobile NAPL, can represent continuing sources of ground water contamination. In order to develop rational and cost-effective plans for remediation of soil and ground water contamination at such sites, it is essential to determine if non-aqueous phase liquid (NAPL) chemicals are present in the subsurface and delineate the zones of NAPL contamination. Qualitatively, soil analyses that exhibit chemical concentrations in the percent range or >10,000 mg/kg would generally be considered to indicate the presence of NAPL. However, the results of soil analyses are seldom used in a quantitative manner to assess the possible presence of residual NAPL contamination when chemical concentrations are lower and the presence of NAPL is not obvious. The assessment of the presence of NAPL in soil samples is possible using the results of chemical and physical analyses of the soil, and the fundamental principles of chemical partitioning in unsaturated or saturated soil. The method requires information on the soil of the type typically considered in ground water contamination studies and provides a simple tool for the investigators of chemical spill and waste disposal sites to assess whether soil chemical analyses indicate the presence of residual NAPL in the subsurface

  13. Effectiveness of control strategies against Botrytis cinerea in vineyard and evaluation of the residual fungicide concentrations.

    Science.gov (United States)

    Gabriolotto, Chiara; Monchiero, Matteo; Negre, Michele; Spadaro, Davide; Gullino, Maria Lodovica

    2009-05-01

    This investigation was undertaken to test different control strategies against Botrytis cinerea vineyards. Two commercial vineyards, "Barbera" and "Moscato," located in Piedmont (Northern Italy) were divided into seven plots and treated with different combinations of fungicides including fenhexamid, pyrimethanil, fludioxonil + cyprodinil, iprodione, and boscalid, a new carboxamide compound. An integrated strategy including a chemical (pyrimethanil) and a biocontrol agent (Trichoderma spp. t2/4ph1) was also included. At harvest, the percentage of bunches and berries attacked by B. cinerea and the concentration of the chemical fungicides were determined. All the pesticide residues at harvest were below the maximum residue level (MRL), except when two applications of pyrimethanil per season were applied. Boscalid was the most effective active ingredient against B. cinerea among the tested chemicals. When boscalid application was followed by a treatment with pyrimethanil, its efficacy was similar to that shown by two treatments of pyrimethanil. However, this second strategy was not feasible due to the risks of resistance development in the pathogen and to the residue accumulation as indicated by the analysis.

  14. The Reaction of Oxy Hemoglobin with Nitrite

    DEFF Research Database (Denmark)

    Hathazi, Denisa; Scurtu, Florina; Bischin, Cristina

    2018-01-01

    The autocatalytic reaction between nitrite and the oxy form of globins involves free radicals. For myoglobin (Mb), an initial binding of nitrite to the iron-coordinated oxygen molecule was proposed; the resulting ferrous-peroxynitrate species was not detected, but its decay product, the high...... to a simple kinetic model involving a transient met-aqua form, in contrast to the ferryl detected in the case of Mb in a similar reaction sequence. These data are in line with a previous observation of a transient accumulation of ferryl Hb under auto-catalytic conditions at much lower concentrations......-peroxynitrate. Density functional theory (DFT) calculations support this latter assignment. The reaction allows for differentiating between the reactivities of various chemically modified hemoglobins, including candidates for blood substitutes. Polymerization of hemoglobin slows the nitrite-induced oxidation, in sharp...

  15. Access to residual carrier concentration in ZnO nanowires by calibrated scanning spreading resistance microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, L., E-mail: lin.wang@insa-lyon.fr; Brémond, G. [Institut des Nanotechnologies de Lyon (INL), Université de Lyon, CNRS UMR 5270, INSA Lyon, Bat. Blaise Pascal, 7 Avenue Jean Capelle, 69621 Villeurbanne (France); Chauveau, J. M. [Centre de Recherche sur l' Hétéro-Epitaxie et ses Applications (CRHEA), CNRS UPR10, rue Bernard Grégory 06560 Valbonne Sophia Antipolis (France); Physics Department, University of Nice Sophia Antipolis (UNS), Parc Valrose, 06103 Nice (France); Brenier, R. [Institut Lumière Matière (ILM), Université de Lyon, CNRS UMR 5306, Université Claude Bernard Lyon 1, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne (France); Sallet, V.; Jomard, F.; Sartel, C. [Groupe d' Étude de la Matière Condensée (GEMaC), CNRS-Université de Versailles St Quentin en Yvelines, Université Paris-Saclay, 45 Avenue des Etats-Unis, 78035 Versailles (France)

    2016-03-28

    Scanning spreading resistance microscopy (SSRM) was performed on non-intentionally doped (nid) ZnO nanowires (NWs) grown by metal-organic chemical vapor deposition in order to measure their residual carrier concentration. For this purpose, an SSRM calibration profile has been developed on homoepitaxial ZnO:Ga multilayer staircase structures grown by molecular beam epitaxy. The Ga density measured by SIMS varies in the 1.7 × 10{sup 17 }cm{sup −3} to 3 × 10{sup 20 }cm{sup −3} range. From measurements on such Ga doped multi-layers, a monotonic decrease in SSRM resistance with increasing Ga density was established, indicating SSRM being a well-adapted technique for two dimensional dopant/carrier profiling on ZnO at nanoscale. Finally, relevant SSRM signal contrasts were detected on nid ZnO NWs, and the residual carrier concentration is estimated in the 1–3 × 10{sup 18 }cm{sup −3} range, in agreement with the result from four-probe measurements.

  16. Radiological Modeling for Determination of Derived Concentration Levels of an Area with Uranium Residual Material - 13533

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Sanchez, Danyl [CIEMAT, Avenida Complutense 40, 28040, Madrid (Spain)

    2013-07-01

    As a result of a pilot project developed at the old Spanish 'Junta de Energia Nuclear' to extract uranium from ores, tailings materials were generated. Most of these residual materials were sent back to different uranium mines, but a small amount of it was mixed with conventional building materials and deposited near the old plant until the surrounding ground was flattened. The affected land is included in an area under institutional control and used as recreational area. At the time of processing, uranium isotopes were separated but other radionuclides of the uranium decay series as Th-230, Ra-226 and daughters remain in the residue. Recently, the analyses of samples taken at different ground's depths confirmed their presence. This paper presents the methodology used to calculate the derived concentration level to ensure that the reference dose level of 0.1 mSv y-1 used as radiological criteria. In this study, a radiological impact assessment was performed modeling the area as recreational scenario. The modelization study was carried out with the code RESRAD considering as exposure pathways, external irradiation, inadvertent ingestion of soil, inhalation of resuspended particles, and inhalation of radon (Rn-222). As result was concluded that, if the concentration of Ra-226 in the first 15 cm of soil is lower than, 0.34 Bq g{sup -1}, the dose would not exceed the reference dose. Applying this value as a derived concentration level and comparing with the results of measurements on the ground, some areas with a concentration of activity slightly higher than latter were found. In these zones the remediation proposal has been to cover with a layer of 15 cm of clean material. This action represents a reduction of 85% of the dose and ensures compliance with the reference dose. (authors)

  17. La production de nitrites lors de la dénitrification des eaux usées par biofiltration - Stratégie de contrôle et de réduction des concentrations résiduelles

    OpenAIRE

    Rocher , Vincent; Join , Cédric; Mottelet , Stéphane; Bernier , Jean; Rechdaoui-Guérin , Sabrina; Azimi , Sam; Lessard , Paul; Pauss , André; Fliess , Michel

    2017-01-01

    International audience; The recent popularity of post-denitrification processes in the greater Paris area wastewater treatmentplants has caused a resurgence of the presence of nitrite in the Seine River. Controlling the productionof nitrite during the post-denitrification process has thus become a major technical issue. Researchstudies have been led in the MOCOPEE program (www.mocopee.com) to better understand theunderlying mechanisms behind the production of nitrite during wastewater denitri...

  18. Identification and concentration of selected pesticide residues in Ghanaian cocoa beans

    International Nuclear Information System (INIS)

    Sefakor, Adzo Fialor

    2017-07-01

    Pest and disease have been the major causes of low cocoa production worldwide and the use of chemicals in the form of pesticides is one of the main ways of mitigating their undesirable outcome. However, inappropriate application of pesticides does not only affect the quality of cocoa bean products and the well being of consumers of such products but can also damage the natural flora and fauna in the environment. Hence the reason why evaluating the concentrations of pesticide residues is necessary in establishing the quality of a cocoa. The goal of this study was therefore to determine the concentrations and distribution of specific pesticide residues in cocoa beans from the six cocoa growing regions of Ghana. Three classes of pesticides were tested for in cocoa beans obtained from seventeen (17) districts in the Brong Ahafo, Eastern, Central, Western North, Ashanti and Western South cocoa growing regions of Ghana. These were the neonicotinoids (Thiamethoxam, Clothianidin, Imidacloprid and Acetamiprid); the synthetic pyrethroids (Cypermethrin, Deltamethrin, Fenvalerate, Lambda Cyhalothrin and Permethrin) and the organophosphorous compound Chlorpyrifos. Pesticide residue analyses were done separately on the whole unshelled beans, the nibs and the shells using a GC/ECD for the synthetic pyrethroids and organophosphorous compound and a QqQ-LC/MS for the neonicotinoids. The results obtained showed that the mean concentrations of the neonicotinoids in all the three matrices ranged from <0.001 to 0.018 mg/kg in the shells, <0.001 to 0.0025 mg/kg in the nibs and <0.001 to 0.005 mg/kg in the whole beans with Imidacloprid being the predominant one. Ashanti Region had the highest concentration of Imidacloprid in all the three matrices whilst Eastern Region recorded the least concentration of Imidacloprid in the shells (0.009 mg/kg) and whole unshelled beans (0.002 mg/kg). In relations to the synthetic pyrethroids tested for, the results obtained indicated that out of the

  19. Anoxic sulfide biooxidation using nitrite as electron acceptor

    International Nuclear Information System (INIS)

    Mahmood, Qaisar; Zheng Ping; Cai Jing; Wu Donglei; Hu, Baolan; Li Jinye

    2007-01-01

    Biotechnology can be used to assess the well being of ecosystems, transform pollutants into benign substances, generate biodegradable materials from renewable sources, and develop environmentally safe manufacturing and disposal processes. Simultaneous elimination of sulfide and nitrite from synthetic wastewaters was investigated using a bioreactor. A laboratory scale anoxic sulfide-oxidizing (ASO) reactor was operated for 135 days to evaluate the potential for volumetric loading rates, effect of hydraulic retention time (HRT) and substrate concentration on the process performance. The maximal sulfide and nitrite removal rates were achieved to be 13.82 and 16.311 kg/(m 3 day), respectively, at 0.10 day HRT. The process can endure high sulfide concentrations, as the sulfide removal percentage always remained higher than 88.97% with influent concentration up to 1920 mg/L. Incomplete sulfide oxidation took place due to lower consumed nitrite to sulfide ratios of 0.93. It also tolerated high nitrite concentration up to 2265.25 mg/L. The potential achieved by decreasing HRT at fixed substrate concentration is higher than that by increasing substrate concentration at fixed HRT. The process can bear short HRT of 0.10 day but careful operation is needed. Nitrite conversion was more sensitive to HRT than sulfide conversion when HRT was decreased from 1.50 to 0.08 day. Stoichiometric analyses and results of batch experiments show that major part of sulfide (89-90%) was reduced by nitrite while some autooxidation (10-11%) was resulted from presence of small quantities of dissolved oxygen in the influent wastewater. There was ammonia amassing in considerably high amounts in the bioreactor when the influent nitrite concentration reached above 2265.25 mg/L. High ammonia concentrations (200-550 mg/L) in the bioreactor contributed towards the overall inhibition of the process. Present biotechnology exhibits practical value with a high potential for simultaneous removal of nitrite

  20. Nitrogen removal and electricity production at a double-chamber microbial fuel cell with cathode nitrite denitrification.

    Science.gov (United States)

    Yu, Yangyang; Zhao, Jianqiang; Wang, Sha; Zhao, Huimin; Ding, Xiaoqian; Gao, Kun

    2017-12-01

    Double-chamber microbial fuel cell was applied to investigate the performance of the electricity production and nitrite denitrification through feeding nitrite into the cathode. Factors influencing denitrification performance and power production, such as external resistance, influent nitrite concentration and Nitrite Oxygen Bacteria inhibitors, were studied. The results show that when the concentration of nitrite nitrogen and external resistance were 100 mg L -1 and 10 Ω, respectively, the nitrite denitrification reached the best state. The NaN 3 can inhibit nitrite oxidation effectively; meanwhile, the nitrite denitrification with N 2 O as the final products was largely improved. The [Formula: see text] was reduced to [Formula: see text], causing the cathode denitrification coulombic efficiency to exceed 100%. In chemoautotrophic bio-nitrification, microorganisms may utilize H 2 O to oxidize nitrite under anaerobic conditions. Proteobacteria might play a major role in the process of denitrification in MFC.

  1. Arsenic Species in Chicken Breast: Temporal Variations of Metabolites, Elimination Kinetics, and Residual Concentrations.

    Science.gov (United States)

    Liu, Qingqing; Peng, Hanyong; Lu, Xiufen; Zuidhof, Martin J; Li, Xing-Fang; Le, X Chris

    2016-08-01

    Chicken meat has the highest per capita consumption among all meat types in North America. The practice of feeding 3-nitro-4-hydroxyphenylarsonic acid (Roxarsone, Rox) to chickens lasted for more than 60 years. However, the fate of Rox and arsenic metabolites remaining in chicken are poorly understood. We aimed to determine the elimination of Rox and metabolites from chickens and quantify the remaining arsenic species in chicken meat, providing necessary information for meaningful exposure assessment. We have conducted a 35-day feeding experiment involving 1,600 chickens, of which half were control and the other half were fed a Rox-supplemented diet for the first 28 days and then a Rox-free diet for the final 7 days. We quantified the concentrations of individual arsenic species in the breast meat of 229 chickens. Rox, arsenobetaine, arsenite, monomethylarsonic acid, dimethylarsinic acid, and a new arsenic metabolite, were detected in breast meat from chickens fed Rox. The concentrations of arsenic species, except arsenobetaine, were significantly higher in the Rox-fed than in the control chickens. The half-lives of elimination of these arsenic species were 0.4-1 day. Seven days after termination of Rox feeding, the concentrations of arsenite (3.1 μg/kg), Rox (0.4 μg/kg), and a new arsenic metabolite (0.8 μg/kg) were significantly higher in the Rox-fed chickens than in the control. Feeding of Rox to chickens increased the concentrations of five arsenic species in breast meat. Although most arsenic species were excreted rapidly when the feeding of Rox stopped, arsenic species remaining in the Rox-fed chickens were higher than the background levels. Liu Q, Peng H, Lu X, Zuidhof MJ, Li XF, Le XC. 2016. Arsenic species in chicken breast: temporal variations of metabolites, elimination kinetics, and residual concentrations. Environ Health Perspect 124:1174-1181; http://dx.doi.org/10.1289/ehp.1510530.

  2. Rapid detection of chlorpyrifos pesticide residue concentration in agro-product using Raman spectroscopy

    Science.gov (United States)

    Dhakal, Sagar; Peng, Yankun; Li, Yongyu; Chao, Kuanglin; Qin, Jianwei; Zhang, Leilei; Xu, Tianfeng

    2014-05-01

    Different chemicals are sprayed in fruits and vegetables before and after harvest for better yield and longer shelf-life of crops. Cases of pesticide poisoning to human health are regularly reported due to excessive application of such chemicals for greater economic benefit. Different analytical technologies exist to detect trace amount of pesticides in fruits and vegetables, but are expensive, sample destructive, and require longer processing time. This study explores the application of Raman spectroscopy for rapid and non-destructive detection of pesticide residue in agricultural products. Raman spectroscopy with laser module of 785 nm was used to collect Raman spectral information from the surface of Gala apples contaminated with different concentrations of commercially available organophosphorous (48% chlorpyrifos) pesticide. Apples within 15 days of harvest from same orchard were used in this study. The Raman spectral signal was processed by Savitzky-Golay (SG) filter for noise removal, Multiplicative Scatter Correction (MSC) for drift removal and finally polynomial fitting was used to eliminate the fluorescence background. The Raman spectral peak at 677 cm-1 was recognized as Raman fingerprint of chlorpyrifos. Presence of Raman peak at 677 cm-1 after fluorescence background removal was used to develop classification model (presence and absence of pesticide). The peak intensity was correlated with actual pesticide concentration obtained using Gas Chromatography and MLR prediction model was developed with correlation coefficient of calibration and validation of 0.86 and 0.81 respectively. Result shows that Raman spectroscopy is a promising tool for rapid, real-time and non-destructive detection of pesticide residue in agro-products.

  3. Metabolic fates and effects of nitrite in brown trout under normoxic and hypoxic conditions: blood and tissue nitrite metabolism and interactions with branchial NOS, Na+/K+-ATPase and hsp70 expression

    DEFF Research Database (Denmark)

    Jensen, Frank Bo; Gerber, Lucie; Hansen, Marie Niemann

    2015-01-01

    were higher in hypoxia than normoxia, suggesting increased NOS activity. Nitrite exposure strongly elevated nitrite concentrations in plasma, erythrocytes, heart tissue and white muscle, which was associated with an extensive metabolism of nitrite to nitrate and to iron-nitrosylated and S......Nitrite secures essential nitric oxide (NO) bioavailability in hypoxia at low endogenous concentrations, whereas it becomes toxic at high concentrations. We exposed brown trout to normoxic and hypoxic water in the absence and presence of added ambient nitrite to decipher the cellular metabolism...... and effects of nitrite at basal and elevated concentrations under different oxygen regimes. We also tested hypotheses concerning the influence of nitrite on branchial nitric oxide synthase (NOS), Na+/K+-ATPase (nka) and heat shock protein (hsp70) mRNA expression. Basal plasma and erythrocyte nitrite levels...

  4. Evaluation of droplet digital PCR for quantification of residual leucocytes in red blood cell concentrates.

    Science.gov (United States)

    Doescher, A; Loges, U; Petershofen, E K; Müller, T H

    2017-11-01

    Enumeration of residual white blood cells in leucoreduced blood components is essential part of quality control. Digital PCR has substantially facilitated quantitative PCR and was thus evaluated for measurements of leucocytes. Target for quantification of leucocytes by digital droplet PCR was the blood group gene RHCE. The SPEF1 gene was added as internal control for the entire assay starting with automated DNA extraction. The sensitivity of the method was determined by serial dilutions of standard samples. Quality control samples were analysed within 24 h, 7 days and 6 months after collection. Routine samples from leucodepleted red blood cell concentrates (n = 150) were evaluated in parallel by flow-cytometry (LeucoCount) and by digital PCR. Digital PCR reliably detected at least 0·4 leucocytes per assay. The mean difference between PCR and flow-cytometric results from 150 units was -0·01 (±1·0). DNA samples were stable for up to at least six months. PCR measurement of leucocytes in samples from plasma and platelet concentrates also provided valid results in a pilot study. Droplet digital PCR to enumerate leucocytes offers an alternative for quality control of leucoreduced blood products. Sensitivity, specificity and reproducibility are comparable to flow-cytometry. The option to collect samples over an extended period of time and the automatization introduce attractive features for routine quality control. © 2017 International Society of Blood Transfusion.

  5. Estimation of human body concentrations of DDT from indoor residual spraying for malaria control

    International Nuclear Information System (INIS)

    Gyalpo, Tenzing; Fritsche, Lukas; Bouwman, Henk; Bornman, Riana; Scheringer, Martin; Hungerbühler, Konrad

    2012-01-01

    Inhabitants of dwellings treated with DDT for indoor residual spraying show high DDT levels in blood and breast milk. This is of concern since mothers transfer lipid-soluble contaminants such as DDT via breastfeeding to their children. Focusing on DDT use in South Africa, we employ a pharmacokinetic model to estimate DDT levels in human lipid tissue over the lifetime of an individual to determine the amount of DDT transferred to children during breastfeeding, and to identify the dominant DDT uptake routes. In particular, the effects of breastfeeding duration, parity, and mother's age on DDT concentrations of mother and infant are investigated. Model results show that primiparous mothers have greater DDT concentrations than multiparous mothers, which causes higher DDT exposure of first-born children. DDT in the body mainly originates from diet. Generally, our modeled DDT levels reproduce levels found in South African biomonitoring data within a factor of 3. - Highlights: ► Comparison of one-compartment pharmacokinetic model with biomonitoring data. ► Pre- and postnatal exposure of infants depends on breastfeeding duration and parity. ► Dietary exposure of DDT is the dominant uptake route in South Africa. ► Elimination half-lives of DDT and DDE are shorter in children than in adults. - Model predictions of a one-compartment pharmacokinetic model confirm the trends of DDT found in human samples of inhabitants living in DDT-treated dwellings.

  6. 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.

  7. Optimization of the protein concentration process from residual peanut oil-cake

    Directory of Open Access Journals (Sweden)

    Gayol, M. F.

    2013-12-01

    Full Text Available The objective of this study was to find the best process conditions for preparing protein concentrate from residual peanut oil-cake (POC. The study was carried out on POC from industrial peanut oil extraction. Different protein extraction and precipitation conditions were used: water/ flour ratio (10:1, 20:1 and 30:1, pH (8, 9 and 10, NaCl concentration (0 and 0.5 M, extraction time (30, 60 and 120 min, temperature (25, 40 and 60 °C, extraction stages (1, 2 and 3, and precipitation pH (4, 4.5 and 5. The extraction and precipitation conditions which showed the highest protein yield were 10:1 water/flour ratio, extraction at pH 9, no NaCl, 2 extraction stages of 30 min at 40 °C and precipitation at pH 4.5. Under these conditions, the peanut protein concentrate (PC contained 86.22% protein, while the initial POC had 38.04% . POC is an alternative source of protein that can be used for human consumption or animal nutrition. Therefore, it adds value to an industry residue.El objetivo de este trabajo fue encontrar las mejores condiciones para obtener un concentrado de proteínas a partir de la torta residual de maní (POC. El estudio se llevó a cabo en POC provenientes de la extracción industrial de aceite de maní. Se utilizaron distintas condiciones para la extracción y precipitación de proteínas: relación agua / harina (10:1, 20:1 y 30:1, pH de extracción (8, 9 y 10, concentración de NaCl (0 y 0,5 M, tiempo de extracción (30, 60 y 120 min, temperatura (25, 40 y 60 °C, número de etapas de extracción (1, 2 y 3, y el pH de precipitación (4, 4,5 y 5. Las condiciones de extracción y de precipitación que mostraron mayor rendimiento de proteína fueron: relación de 10:1 en agua / harina, pH de extracción de 9, en ausencia de NaCl, 2 etapas de extracción de 30 min cada una a 40 °C y el pH de precipitación de 4,5. En estas condiciones, el concentrado de proteína de maní (PC fue de 86,22%, mientras que el porcentaje de proteínas de

  8. Electrochemical oxidation of nitrite on nanodiamond powder electrode

    Energy Technology Data Exchange (ETDEWEB)

    Chen, L.H.; Zang, J.B.; Wang, Y.H.; Bian, L.Y. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China)

    2008-03-10

    Nanodiamond (ND) powder electrodes were fabricated and the electrochemical properties were investigated in the solution containing nitrite in this article. This electrode exhibits substantial catalytic ability toward the oxidation of nitrite anions. The electrochemical oxidation mechanism of nitrite on the ND powder electrode is discussed. The oxidation of NaNO{sub 2} is a two-electron transfer process. The electrode reaction rate constant k is estimated to be 2.013 x 10{sup -4} cm/s and (1 - {alpha})n{sub {alpha}} is 0.1643. The peak current increases linearly with the rising of the concentration of NaNO{sub 2}. (author)

  9. Pre-concentration of pesticide residues in environmental water samples using Silica nanoparticles and identification of residues By GC-MS method

    OpenAIRE

    Tentu. Nageswara Rao; A. Muralidhar Reddy; SNVS. Murthy; Prathipati Revathi; K. Suneel Kumar

    2016-01-01

    The silica nanoparticles prepared by stober’s mechanism by reaction of tetraethylorthosilicate (TEOS) with ammonia was tested for their adsorption capacity in the pre-concentration of residues of pesticides in water. The synthesized nanoparticles were characterized by Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and X-Ray Diffraction (XRD). The size of the silica nanoparticles were 50 to 250 nm. The solid phase extraction (SPE) cartridges were prepared by filling...

  10. Recovery of sulfur from residue gases of low H/sub 2/S concentration

    Energy Technology Data Exchange (ETDEWEB)

    Bratzler, K; Doerges, A; Schlauer, J

    1976-01-01

    The Lucas process is intended for reduction of SO/sub 2/ and H/sub 2/S in Claus tail gas or other low-sulfur residue gases to levels below 200 ppm (H/sub 2/S only in traces). In the first stage, all sulfur compounds are burned to SO/sub 2/; in the second stage, a coke reactor reduces SO/sub 3/ and O/sub 2/; and in the third stage, the SO/sub 2/ is absorbed in an aqueous alkali phosphate solution. Concentrated SO/sub 2/ from regeneration of the solution is returned to the Claus plant, or can be catalystically reduced to elemental sulfur. The process was proven out in a semitechnical pilot plant, with satisfactory results as follows: sulfur recovery, 97 to 99.8%; energy consumption per 1,000 cu m feed gas, 2.6 to 3.7 kw-hr plus 860 to 930 MJ heating gas (however, 300 to 350 kg steam was generated); 0.15 kg chemicals; 0.7 to 1.5 kg coke; and a minimal amount of catalyst if sulfur is produced. Investment is only 60 to 80% of that in a 2-stage Claus process, with which the Lucas process is competitive.

  11. A Review of Nitrate and Nitrite Toxicity in Foods

    Directory of Open Access Journals (Sweden)

    Mir-Jamal Hosseini

    2016-03-01

    Full Text Available Agricultural advancement and population growth have prompted increases in food supplies, and higher crop yields have been made possible through the application of fertilizers. Large quantities of livestock and poultry on farms, along with the accumulation of biomass and agricultural residues, can cause contamination of ground water resources and other water sanitation concerns in both developing and developed countries. Nitrate is mainly used as a fertilizer in agriculture, and because of its high solubility in water, it can create biological problems in the environment. High usage of nitrite in the food industry as a preservative, flavor enhancer, antioxidant, and color stabilizing agent can cause human exposure to this toxic compound. Nitrite is 10 times as toxic as nitrate in humans. Nitrate is converted to nitrite and nitrosamine compounds in the human stomach, which can lead to bladder cancer. In this review, sources of nitrate and nitrite exposure were investigated. Furthermore, the review evaluates standard levels of nitrate and nitrite in different foods, and acceptable daily doses of these compounds in various countries. Finally, we discuss valid methods of nitrate and nitrite identification and removal in foods.

  12. [The method to remove nitrite from tap water by tea].

    Science.gov (United States)

    Lu, M; Chen, L; Xian, H

    1997-03-01

    Drinking water (tap water) is polluted in pipelines by bacteria after long distance transportation. The water contains nitrite (NO2-) which is potentially harmful to human health. The nitrite concentrations range from 0.10 to 2.0 mg/L. Our experiment proved that NO2- could not be removed by boiling, but could be removed by tea. As a natural antioxidant, tea contains several antioxidants, such as ascorbic acid and catechins, which removed NO2- from tap water effectively.

  13. Yield of Ozone, Nitrite Nitrogen and Hydrogen Peroxide Versus Discharge Parameter Using APPJ Under Water

    International Nuclear Information System (INIS)

    Chen Bingyan; Wen Wen; Zhu Changping; Wang Yuan; Gao Ying; Fei Juntao; He Xiang; Yin Cheng; Jiang Yongfeng; Chen Longwei

    2016-01-01

    Discharge plasma in and in contact with water can be accompanied with ultraviolet radiation and electron impact, thus can generate hydroxyl radicals, ozone, nitrite nitrogen and hydrogen peroxide. In this paper, a non-equilibrium plasma processing system was established by means of an atmospheric pressure plasma jet immersed in water. The hydroxyl intensities and discharge energy waveforms were tested. The results show that the positive and negative discharge energy peaks were asymmetric, where the positive discharge energy peak was greater than the negative one. Meanwhile, the yield of ozone and nitrite nitrogen was enhanced with the increase of both the treatment time and the discharge energy. Moreover, the pH value of treated water was reduced rapidly and maintained at a lower level. The residual concentration of hydrogen peroxide in APPJ treated water was kept at a low level. Additionally, both the efficiency energy ratio of the yield of ozone and nitrite nitrogen and that of the removal of p-nitrophenol increased as a function of discharge energy and discharge voltage. The experimental results were fully analyzed and the chemical reaction equations and the physical processes of discharges in water were given. (paper)

  14. Evaluation of Nitrate and Nitrite Reduction Kinetics Related to Liquid-Air-Interface Corrosion

    International Nuclear Information System (INIS)

    Li, Xiaoji; Gui, F.; Cong, Hongbo; Brossia, C.S.; Frankel, G.S.

    2014-01-01

    Liquid-air interface (LAI) corrosion has been a concern for causing leaks in the carbon steel tanks used for holding high-level radioactive liquid waste. To assist in understanding the mechanism of LAI corrosion, the kinetics of nitrate and nitrite reduction reactions were investigated electrochemically. Cyclic voltammetry and cathodic polarization measurements indicated that the nitrite reduction reaction exhibited faster kinetics than the nitrate reduction reaction at higher cathodic overpotential. However, the primary reduction reaction at the open circuit potential under aerated conditions was the oxygen reduction reaction. The reduction of residual oxygen was also the dominant cathodic reaction at open circuit potential in deaerated conditions. Moreover, the kinetics of oxygen reduction on steel electrodes were significantly influenced by the sample immersion conditions (partial vs. full) for aerated liquid nuclear waste simulants, but not for deaerated conditions. Lastly, the gaseous products formed during LAI corrosion were analyzed using the gas detector tube method and gas chromatography-mass spectrometry and found to contain NH 3 , NO 2 and NO. However, the results suggested that these products were caused by the local acidification generated by the hydrolysis of cations after LAI corrosion underwent extensive propagation, instead of being directly reduced in alkaline conditions. Thus, the results in this work showed that the kinetics of nitrate and nitrite reduction could not generate a salt concentration cell in the meniscus region to cause LAI corrosion

  15. Partial substitution of nitrite by chitosan and the effect on the quality properties of pork sausages

    Directory of Open Access Journals (Sweden)

    Mario García

    2011-06-01

    Full Text Available The aim of the study was to evaluate the influence of partial nitrite replacement by chitosan on the quality of Ham Visking (a type of pork sausages. Five Ham Visking formulations were elaborated modifying the sodium nitrite (0.011; 0.016 or 0.0212% and chitosan concentrations (0.25 or 0.5% in the products. Sausages were stored at 4 ºC and physicochemical, microbiological, and sensorial evaluations were performed in order to estimate their shelf life. Chitosan can be used in pork sausages without affecting ensory attributes such as color although the panelists detected textural differences among the samples with chitosan, which suggests that there is some influence of deacetylation degree of chitosan on the textural behavior of sausages which still needed to be explained for a successful application of chitosan in meat products. The reduction of residual sodium nitrite did not affect the color and flavor of such products, but the use of chitosan increasedsignificantly the shelf life of sausages.

  16. Performance of denitrifying microbial fuel cell with biocathode over nitrite

    Directory of Open Access Journals (Sweden)

    Zhao eHuimin

    2016-03-01

    Full Text Available Microbial fuel cell (MFC with nitrite as an electron acceptor in cathode provided a new technology for nitrogen removal and electricity production simultaneously. The influences of influent nitrite concentration and external resistance on the performance of denitrifying MFC were investigated. The optimal effectiveness were obtained with the maximum total nitrogen (TN removal rate of 54.80±0.01 g m-3 d-1. It would be rather desirable for the TN removal than electricity generation at lower external resistance. Denaturing gradient gel electrophoresis suggested that Proteobacteria was the predominant phylum, accounting for 35.72%. Thiobacillus and Afipia might benefit to nitrite removal. The presence of nitrifying Devosia indicated that nitrite was oxidized to nitrate via a biochemical mechanism in the cathode. Ignavibacterium and Anaerolineaceae was found in the cathode as a heterotrophic bacterium with sodium acetate as substrate, which illustrated that sodium acetate in anode was likely permeated through proton exchange membrane to the cathode .

  17. 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.

  18. Influence of bleaching on flavor of 34% whey protein concentrate and residual benzoic acid concentration in dried whey products

    Science.gov (United States)

    Previous studies have shown that bleaching negatively affects the flavor of 70% whey protein concentrate (WPC70), but bleaching effects on lower-protein products have not been established. Benzoyl peroxide (BP), a whey bleaching agent, degrades to benzoic acid (BA) and may elevate BA concentrations...

  19. Influence of Bleaching on Flavor of 34% Whey Protein Concentrate and Residual Benzoic Acid Concentration in Dried Whey Proteins

    Science.gov (United States)

    Previous studies have shown that bleaching negatively affects the flavor of 70% whey protein concentrate (WPC70), but bleaching effects on lower-protein products have not been established. Benzoyl peroxide (BP), a whey bleaching agent, degrades to benzoic acid (BA) and may elevate BA concentrations...

  20. Residual antibiofilm effects of various concentrations of double antibiotic paste used during regenerative endodontics after different application times.

    Science.gov (United States)

    Jenks, Daniel B; Ehrlich, Ygal; Spolnik, Kenneth; Gregory, Richard L; Yassen, Ghaeth H

    2016-10-01

    We investigated the residual antibiofilm effects of different concentrations of double antibiotic paste (DAP) applied on radicular dentin for 1 or 4 weeks. Dentin samples were prepared (n=120), sterilized and pretreated for 1 or 4 weeks with the clinically used concentration of DAP (500mg/mL), low concentrations of DAP (1, 5 or 50mg/mL) loaded into a methylcellulose system, calcium hydroxide (Ca(OH) 2 ), or placebo paste. After the assigned treatment time, treatment pastes were rinsed off and the samples were kept independently in phosphate buffered saline for 3 weeks. Pretreated dentin samples were then inoculated with Enterococcus faecalis and bacterial biofilms were allowed to grow for an additional 3 weeks. Biofilms were then retrieved from dentin using biofilm disruption assays, diluted, spiral plated, and quantified. Fisher's Exact and Wilcoxon rank sum tests were used for statistical comparisons (α=0.05). Dentin pretreatment for 4 weeks with 5, 50 or 500mg/mL of DAP demonstrated significantly higher residual antibiofilm effects and complete eradication of E. faecalis biofilms in comparison to a 1 week pretreatment with similar concentrations. However, dentin pretreated with 1mg/mL of DAP or Ca(OH) 2 did not provide a substantial residual antibiofilm effect regardless of the application time. Dentin pretreatment with 5mg/mL of DAP or higher for 4 weeks induced significantly higher residual antibiofilm effects in comparison to a 1 week pretreatment with the same concentrations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. THE SPECTROPHOTOMETRIC DETERMINATION OF NITRITES WITH N,N-DIETHYLANILINE

    Directory of Open Access Journals (Sweden)

    O. S. Pogrebnyak

    2015-11-01

    Full Text Available A new spectrophotometric method for nitrite determination was proposed. The method is based on the measurement of absorbance of the N,N-diethylaniline nitrosation product at 475 nm in the hydrochloric acid medium. The optimum concentrations and the influence of various conditions on the determination sensitivity have been determined. The detection limit (blank + 3s for nitrite is 0.98 mg∙L–1 where sis the standard deviation of blank estimation. The linearity range of the calibration graph was over 1.0–100 mg∙L–1 of  nitrite (sr≤ 0.029, n = 8. The metrological characteristics of the procedure were checked by means of method of additives on the control samples and natural waters. The relative error did not exceed 0.06 for nitrite determination on the control samples. The effect of foreign ions in nitrite determination of 1,0∙10−3 mol∙L–1 has been studied. The proposed procedure is simple  and suitable for nitrite determination in various objects.

  2. Determination of nitrite, nitrate and total nitrogen in vegetable samples

    Directory of Open Access Journals (Sweden)

    Manas Kanti Deb

    2007-04-01

    Full Text Available Yellow diazonium cation formed by reaction of nitrite with 6-amino-1-naphthol-3-sulphonic acid is coupled with β-naphthol in strong alkaline medium to yield a pink coloured azo dye. The azo-dyes shows absorption maximum at 510 nm with molar absorptivity of 2.5 ×104 M-1 cm-1. The dye product obeys Beer's law (correlation coefficient = 0.997, in terms of nitrite concentration, up to 2.7 μg NO2 mL-1. The above colour reaction system has been applied successfully for the determination of nitrite, nitrate and total nitrogen in vegetable samples. Unreduced samples give direct measure for nitrite whilst reduction of samples by copperized-cadmium column gives total nitrogen content and their difference shows nitrate content in the samples. Variety of vegetables have been tested for their N-content (NO2-/NO3-/total-N with % RSD ranging between 1.5 to 2.5 % for nitrite determination. The effects of foreign ions in the determination of the nitrite, nitrate, and total nitrogen have been studied. Statistical comparison of the results with those of reported method shows good agreement and indicates no significant difference in precision.

  3. EVALUATION OF FERRIC CHLORIDE AND ALUM EFFICIENCIES IN ENHANCED COAGULATION FOR TOC REMOVAL AND RELATED RESIDUAL METAL CONCENTRATIONS

    Directory of Open Access Journals (Sweden)

    A. Mesdaghinia, M. T. Rafiee, F. Vaezi and A. H. Mahvi

    2005-07-01

    Full Text Available Although the removal of colloidal particles continues to be an important reason for using coagulation, a newer objective, the removal of natural organic matter (NOM to reduce the formation of disinfection by-products (DBPs, is growing in importance. Enhanced coagulation is thus introduced to most water utilities treating surface water. Bench-scale experiments were conducted to compare the effectiveness of alum and ferric chloride in removing DBPs precursors from eight synthetic water samples, each representing a different element of the USEPA’s 3×3 enhanced coagulation matrix. The effect of enhanced coagulation on the residual metal (aluminum/iron concentration in the treated water was assessed as well. The removal of total organic carbon (TOC was dependent on the coagulant type and was enhanced with increasing coagulant dose, but the latter had no further considerable effect in case of increasing to high levels. For all the treated samples coagulation with ferric chloride proved to be more effective than alum at similar doses and the mean values of treatment efficiencies were 51% and 32% for ferric chloride and alum, respectively. Ferric chloride was therefore considered the better chemical for enhancing the coagulation process. Besides, due to less production of sludge by this coagulant, it would be predicted that treatment plants would be confronted to fewer problems with respect to final sludge disposal. Measurements of residual metal in treated water indicated that iron and aluminum concentrations had been increased as expected but the quality of water concerning the residual metal deteriorated much more in cases of under-dosing. Despite expecting high residual Al and Fe concentrations under enhanced coagulation, metal concentrations were frequently remained low and were not increased appreciably.

  4. Modelling nitrite dynamics and associated feedback processes in the Benguela oxygen minimum zone

    Science.gov (United States)

    Mashifane, T. B.; Vichi, M.; Waldron, H. N.; Machu, E.; Garçonc, V.

    2016-08-01

    Understanding nitrite dynamics in oxygen minimum zones (OMZs) is a challenge as it represents an intermediary nitrogen species with a short turnover time. Nitrite is also reduced to nitrogen in OMZs, preventing its accumulation. This creates difficulties in detecting nitrite with colorimetric methods as concentrations may occur below detection limits in some regions. Nitrite concentrations are key to understanding intermediate nitrogen processes and their implication for nitrogen loss in OMZs. A coupled physical-biogeochemical model is applied in the Benguela OMZ to study nitrite dynamics and its associated feedback processes. Simulated results show occurrence of primary and secondary nitrite maxima in the Benguela shelf waters. The primary nitrite maxima in the Benguela are attributed to nitrification and nitrate assimilation as they occur in association with the nitracline. Secondary nitrite maxima accumulate in the Angola-Benguela Front (ABF) OMZ and are attributed to denitrification. The secondary nitrite maxima are consumed by anaerobic ammonium oxidation (anammox) off Walvis Bay. Nitrite maxima are restricted to the shelf off Walvis Bay and advected offshore in the ABF region. Interchanges between the poleward South Atlantic Central Water (SACW) and the equatorward, well-aerated Eastern South Atlantic Central Water (ESACW) drive the seasonality of nitrogen processes in the Benguela. Subsequent nitrite reduction in the Benguela OMZ leads to nitrous oxide production, with high concentrations occurring in the ABF region as a result of nitrification and denitrification. Off Walvis Bay, nitrous oxide production is low since nitrite is consumed by anammox. Nitrous oxide production occurs in thermocline, intermediate and deeper water masses in the ABF region. High N fluxes in the Benguela are attributed to nitrification as compared to anammox and denitrification. Results from this study demonstrate the role of intermediate nitrogen species in nitrogen feedback

  5. Practical Use of Nitrite and Basis for Dosage in the Manufacture of Meat Products

    DEFF Research Database (Denmark)

    Adler-Nissen, Jens; Ekgreen, Maria Helbo; Risum, Jørgen

    . The particularities of the production methods make such a quantification rather uncertain. Furthermore, some dry cured products from South Europe are made with nitrate, which slowly and only partly is converted to nitrite and further to NO during the curing process. The Danish limitations on the use of nitrate......The use of nitrite (NaNO2) in the manufacture of salted (cured) meat products has a long tradition in the industry, dating back to the early twentieth century. Nitrite serves several technological purposes, primarily by the formation of a stable red colour in the meat and the inhibition...... of the growth of Clostridium botulinum. According to an assessment report by the European Food Safety Authority (The EFSA Journal, 14, p. 1-134, 2003) all evidence points to that it is the added amount of nitrite rather than the residual amount of nitrite in the product which exerts the antimicrobial effect...

  6. Nitrate reduction to nitrite, nitric oxide and ammonia by gut bacteria under physiological conditions.

    Directory of Open Access Journals (Sweden)

    Mauro Tiso

    Full Text Available The biological nitrogen cycle involves step-wise reduction of nitrogen oxides to ammonium salts and oxidation of ammonia back to nitrites and nitrates by plants and bacteria. Neither process has been thought to have relevance to mammalian physiology; however in recent years the salivary bacterial reduction of nitrate to nitrite has been recognized as an important metabolic conversion in humans. Several enteric bacteria have also shown the ability of catalytic reduction of nitrate to ammonia via nitrite during dissimilatory respiration; however, the importance of this pathway in bacterial species colonizing the human intestine has been little studied. We measured nitrite, nitric oxide (NO and ammonia formation in cultures of Escherichia coli, Lactobacillus and Bifidobacterium species grown at different sodium nitrate concentrations and oxygen levels. We found that the presence of 5 mM nitrate provided a growth benefit and induced both nitrite and ammonia generation in E.coli and L.plantarum bacteria grown at oxygen concentrations compatible with the content in the gastrointestinal tract. Nitrite and ammonia accumulated in the growth medium when at least 2.5 mM nitrate was present. Time-course curves suggest that nitrate is first converted to nitrite and subsequently to ammonia. Strains of L.rhamnosus, L.acidophilus and B.longum infantis grown with nitrate produced minor changes in nitrite or ammonia levels in the cultures. However, when supplied with exogenous nitrite, NO gas was readily produced independently of added nitrate. Bacterial production of lactic acid causes medium acidification that in turn generates NO by non-enzymatic nitrite reduction. In contrast, nitrite was converted to NO by E.coli cultures even at neutral pH. We suggest that the bacterial nitrate reduction to ammonia, as well as the related NO formation in the gut, could be an important aspect of the overall mammalian nitrate/nitrite/NO metabolism and is yet another way in

  7. Nitrate Reduction to Nitrite, Nitric Oxide and Ammonia by Gut Bacteria under Physiological Conditions

    Science.gov (United States)

    Tiso, Mauro; Schechter, Alan N.

    2015-01-01

    The biological nitrogen cycle involves step-wise reduction of nitrogen oxides to ammonium salts and oxidation of ammonia back to nitrites and nitrates by plants and bacteria. Neither process has been thought to have relevance to mammalian physiology; however in recent years the salivary bacterial reduction of nitrate to nitrite has been recognized as an important metabolic conversion in humans. Several enteric bacteria have also shown the ability of catalytic reduction of nitrate to ammonia via nitrite during dissimilatory respiration; however, the importance of this pathway in bacterial species colonizing the human intestine has been little studied. We measured nitrite, nitric oxide (NO) and ammonia formation in cultures of Escherichia coli, Lactobacillus and Bifidobacterium species grown at different sodium nitrate concentrations and oxygen levels. We found that the presence of 5 mM nitrate provided a growth benefit and induced both nitrite and ammonia generation in E.coli and L.plantarum bacteria grown at oxygen concentrations compatible with the content in the gastrointestinal tract. Nitrite and ammonia accumulated in the growth medium when at least 2.5 mM nitrate was present. Time-course curves suggest that nitrate is first converted to nitrite and subsequently to ammonia. Strains of L.rhamnosus, L.acidophilus and B.longum infantis grown with nitrate produced minor changes in nitrite or ammonia levels in the cultures. However, when supplied with exogenous nitrite, NO gas was readily produced independently of added nitrate. Bacterial production of lactic acid causes medium acidification that in turn generates NO by non-enzymatic nitrite reduction. In contrast, nitrite was converted to NO by E.coli cultures even at neutral pH. We suggest that the bacterial nitrate reduction to ammonia, as well as the related NO formation in the gut, could be an important aspect of the overall mammalian nitrate/nitrite/NO metabolism and is yet another way in which the microbiome

  8. Comparison of questionnaire-based estimation of pesticide residue intake from fruits and vegetables with urinary concentrations of pesticide biomarkers.

    Science.gov (United States)

    Chiu, Yu-Han; Williams, Paige L; Mínguez-Alarcón, Lidia; Gillman, Matthew; Sun, Qi; Ospina, Maria; Calafat, Antonia M; Hauser, Russ; Chavarro, Jorge E

    2018-01-01

    We developed a pesticide residue burden score (PRBS) based on a food frequency questionnaire and surveillance data on food pesticide residues to characterize dietary exposure over the past year. In the present study, we evaluated the association of the PRBS with urinary concentrations of pesticide biomarkers. Fruit and vegetable (FV) intake was classified as having high (PRBS≥4) or low (PRBSEARTH study. Two urine samples per man were analyzed for seven biomarkers of organophosphate and pyrethroid insecticides, and the herbicide 2,4-dichlorophenoxyacetic acid. We used generalized estimating equations to analyze the association of the PRBS with urinary concentrations of pesticide biomarkers. Urinary concentrations of pesticide biomarkers were positively related to high pesticide FV intake but inversely related to low pesticide FV intake. The molar sum of urinary concentrations of pesticide biomarkers was 21% (95% confidence interval (CI): 2%, 44%) higher for each one serving/day increase in high pesticide FV intake, and 10% (95% CI: 1%, 18%) lower for each one serving/day increase in low pesticide FV intake. Furthermore, intake of high pesticide FVs positively related to most individual urinary biomarkers. Our findings support the usefulness of the PRBS approach to characterize dietary exposure to select pesticides.

  9. 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.

  10. Combined effects of high hydrostatic pressure and sodium nitrite on color, water holding capacity and texture of frankfurter

    Science.gov (United States)

    Jonas, G.; Csehi, B.; Palotas, P.; Toth, A.; Kenesei, Gy; Pasztor-Huszar, K.; Friedrich, L.

    2017-10-01

    The aim of this study was to investigate the effect of sodium nitrite and high hydrostatic pressure on the color, water holding capacity (WHC) and texture characteristics of frankfurter. Three hundred, 450 and 600 MPa (5 minutes; 20 °C) and 50, 75, 100 and 125 ppm (calculated on weight of meat) sodium nitrite were applied. Parameters were measured right after the pressure treatment. Data were evaluated with two-way analysis of variance (p 0.05) with pressure levels and sodium nitrite amounts as factors. Nitrite reduction significantly increased lightness (L*) and resulted in decreased redness (a*) value. The pressure treatments decreased the lightness at all nitrite concentrations and did not significantly affect the red color of frankfurters. Fifty and 75 ppm nitrite and pressurization at 300 or 450 MPa improved the water holding property of frankfurter. The pressure treatment did not significantly affect the WHC but changing the nitrite amount had significant effect on it. Interactive effect occurred between pressure levels and nitrite concentrations for hardness. The pressure treatment increased and the nitrite reduction decreased hardness. Significant changes were found in cohesiveness at 450 and 600 MPa in frankfurters containing 50 and 75 ppm nitrite: pressure treatment at higher levels and nitrite reduction decreased the value of cohesiveness.

  11. Behavior of Multiclass Pesticide Residue Concentrations during the Transformation from Rose Petals to Rose Absolute.

    Science.gov (United States)

    Tascone, Oriane; Fillâtre, Yoann; Roy, Céline; Meierhenrich, Uwe J

    2015-05-27

    This study investigates the concentrations of 54 multiclass pesticides during the transformation processes from rose petal to concrete and absolute using roses spiked with pesticides as a model. The concentrations of the pesticides were followed during the process of transforming the spiked rose flowers from an organic field into concrete and then into absolute. The rose flowers, the concrete, and the absolute, as well as their transformation intermediates, were analyzed for pesticide content using gas chromatography/tandem mass spectrometry. We observed that all the pesticides were extracted and concentrated in the absolute, with the exception of three molecules: fenthion, fenamiphos, and phorate. Typical pesticides were found to be concentrated by a factor of 100-300 from the rose flowers to the rose absolute. The observed effect of pesticide enrichment was also studied in roses and their extracts from four classically phytosanitary treated fields. Seventeen pesticides were detected in at least one of the extracts. Like the case for the spiked samples in our model, the pesticides present in the rose flowers from Turkey were concentrated in the absolute. Two pesticides, methidathion and chlorpyrifos, were quantified in the rose flowers at approximately 0.01 and 0.01-0.05 mg kg(-1), respectively, depending on the treated field. The concentrations determined for the corresponding rose absolutes were 4.7 mg kg(-1) for methidathion and 0.65-27.25 mg kg(-1) for chlorpyrifos.

  12. High hole mobility p-type GaN with low residual hydrogen concentration prepared by pulsed sputtering

    Science.gov (United States)

    Arakawa, Yasuaki; Ueno, Kohei; Kobayashi, Atsushi; Ohta, Jitsuo; Fujioka, Hiroshi

    2016-08-01

    We have grown Mg-doped GaN films with low residual hydrogen concentration using a low-temperature pulsed sputtering deposition (PSD) process. The growth system is inherently hydrogen-free, allowing us to obtain high-purity Mg-doped GaN films with residual hydrogen concentrations below 5 × 1016 cm-3, which is the detection limit of secondary ion mass spectroscopy. In the Mg profile, no memory effect or serious dopant diffusion was detected. The as-deposited Mg-doped GaN films showed clear p-type conductivity at room temperature (RT) without thermal activation. The GaN film doped with a low concentration of Mg (7.9 × 1017 cm-3) deposited by PSD showed hole mobilities of 34 and 62 cm2 V-1 s-1 at RT and 175 K, respectively, which are as high as those of films grown by a state-of-the-art metal-organic chemical vapor deposition apparatus. These results indicate that PSD is a powerful tool for the fabrication of GaN-based vertical power devices.

  13. Total salivary nitrates and nitrites in oral health and periodontal disease.

    Science.gov (United States)

    Sánchez, Gabriel A; Miozza, Valeria A; Delgado, Alejandra; Busch, Lucila

    2014-01-30

    It is well known that nitrites are increased in saliva from patients with periodontal disease. In the oral cavity, nitrites may derive partly from the reduction of nitrates by oral bacteria. Nitrates have been reported as a defence-related mechanism. Thus, the aim of the present study was to determine the salivary levels of total nitrate and nitrite and their relationship, in unstimulated and stimulated saliva from periodontal healthy subjects, and from patients with chronic periodontal disease. Nitrates and nitrites were determined in saliva from thirty healthy subjects and forty-four patients with periodontal disease. A significant increase in salivary nitrates and nitrites was observed. Nitrates and nitrites concentration was related to clinical attachment level (CAL). A positive and significant Pearson's correlation was found between salivary total nitrates and nitrites. Periodontal treatment induced clinical improvement and decreased nitrates and nitrites. It is concluded that salivary nitrates and nitrites increase, in patients with periodontal disease, could be related to defence mechanisms. The possibility that the salivary glands respond to oral infectious diseases by increasing nitrate secretion should be explored further. Copyright © 2013 Elsevier Inc. All rights reserved.

  14. Color Developing Capacity of Plasma-treated Water as a Source of Nitrite for Meat Curing.

    Science.gov (United States)

    Jung, Samooel; Kim, Hyun Joo; Park, Sanghoo; Yong, Hae In; Choe, Jun Ho; Jeon, Hee-Joon; Choe, Wonho; Jo, Cheorun

    2015-01-01

    The interaction of plasma with liquid generates nitrogen species including nitrite (NO(-) 2). Therefore, the color developing capacity of plasma-treated water (PTW) as a nitrite source for meat curing was investigated in this study. PTW, which is generated by surface dielectric barrier discharge in air, and the increase of plasma treatment time resulted in increase of nitrite concentration in PTW. The PTW used in this study contains 46 ppm nitrite after plasma treatment for 30 min. To evaluate the effect of PTW on the cured meat color, meat batters were prepared under three different conditions (control, non-cured meat batter; PTW, meat batter cured with PTW; Sodium nitrite, meat batter cured with sodium nitrite). The meat batters were vacuum-packaged and cooked in a water-bath at 80℃ for 30 min. The typical color of cured meat developed in cooked meat batter treated with sodium nitrite or PTW. The lightness (L*) and yellowness (b*) values were similar in all conditions, whereas, the redness (a*) values of cooked meat batter with PTW and sodium nitrite (pnitrite source in the curing process of meat without addition of other nitrite sources.

  15. The effects of elevated environmental CO2 on nitrite uptake in the air-breathing clown knifefish, Chitala ornata

    DEFF Research Database (Denmark)

    Le Thi Hong Gam; Jensen, Frank Bo; Do Thi Thanh Huong

    2018-01-01

    hypercapnia) and nitrite for 96 h. Blood was sampled to measure acid-base status, haemoglobin derivatives and plasma ions. Plasma nitrite increased for 48 h, but levels stayed below the exposure concentration, and subsequently decreased as a result of nitrite detoxification to nitrate. The total uptake......Nitrite and carbon dioxide are common environmental contaminants in the intensive aquaculture ponds used to farm clown knifefish (Chitala ornata) in the Mekong delta, Vietnam. Here we tested the hypothesis that hypercapnia reduces nitrite uptake across the gills, because pH regulation will reduce...... chloride uptake and hence nitrite uptake as the two ions compete for the same transport route via the branchial HCO3-/Cl- exchanger. Fish fitted with arterial catheters were exposed to normocapnic/normoxic water (control), nitrite (1 mM), hypercapnia (21 mmHg CO2), or combined hypercapnia (acclimated...

  16. The Effect of Influent Characteristics and Operational Conditions over the Performance and Microbial Community Structure of Partial Nitritation Reactors

    Directory of Open Access Journals (Sweden)

    Alejandro Rodriguez-Sanchez

    2014-06-01

    Full Text Available Nitrogen is a main contaminant of wastewater worldwide. Novel processes for nitrogen removal have been developed over the last several decades. One of these is the partial nitritation process. This process includes the oxidation of ammonium to nitrite without the generation of nitrate. The partial nitritation process has several advantages over traditional nitrification-denitrification processes for nitrogen removal from wastewaters. In addition, partial nitritation is required for anammox elimination of nitrogen from wastewater. Partial nitritation is affected by operational conditions and substances present in the influent, such as quinolone antibiotics. In this review, the impact that several operational conditions, such as temperature, pH, dissolved oxygen concentration, hydraulic retention time and solids retention time, have over the partial nitritation process is covered. The effect of quinolone antibiotics and other emerging contaminants are discussed. Finally, future perspectives for the partial nitritation process are commented upon.

  17. Stable-isotope dilution GC-MS approach for nitrite quantification in human whole blood, erythrocytes, and plasma using pentafluorobenzyl bromide derivatization: nitrite distribution in human blood.

    Science.gov (United States)

    Schwarz, Alexandra; Modun, Darko; Heusser, Karsten; Tank, Jens; Gutzki, Frank-Mathias; Mitschke, Anja; Jordan, Jens; Tsikas, Dimitrios

    2011-05-15

    Previously, we reported on the usefulness of pentafluorobenzyl bromide (PFB-Br) for the simultaneous derivatization and quantitative determination of nitrite and nitrate in various biological fluids by GC-MS using their (15)N-labelled analogues as internal standards. As nitrite may be distributed unevenly in plasma and blood cells, its quantification in whole blood rather than in plasma or serum may be the most appropriate approach to determine nitrite concentration in the circulation. So far, GC-MS methods based on PFB-Br derivatization failed to measure nitrite in whole blood and erythrocytes because of rapid nitrite loss by oxidation and other unknown reactions during derivatization. The present article reports optimized and validated procedures for sample preparation and nitrite derivatization which allow for reliable quantification of nitrite in human whole blood and erythrocytes. Essential measures for stabilizing nitrite in these samples include sample cooling (0-4°C), hemoglobin (Hb) removal by precipitation with acetone and short derivatization of the Hb-free supernatant (5 min, 50°C). Potassium ferricyanide (K(3)Fe(CN)(6)) is useful in preventing Hb-caused nitrite loss, however, this chemical is not absolutely required in the present method. Our results show that accurate GC-MS quantification of nitrite as PFB derivative is feasible virtually in every biological matrix with similar accuracy and precision. In EDTA-anticoagulated venous blood of 10 healthy young volunteers, endogenous nitrite concentration was measured to be 486±280 nM in whole blood, 672±496 nM in plasma (C(P)), and 620±350 nM in erythrocytes (C(E)). The C(E)-to-C(P) ratio was 0.993±0.188 indicating almost even distribution of endogenous nitrite between plasma and erythrocytes. By contrast, the major fraction of nitrite added to whole blood remained in plasma. The present GC-MS method is useful to investigate distribution and metabolism of endogenous and exogenous nitrite in blood

  18. Safety and sensory aspects of nitrite alternatives in meat curing

    International Nuclear Information System (INIS)

    Shahidi, F.; Pegg, R.B.

    1991-01-01

    The use of nitrite to cure meats (especially bacon) is viewed as undesirable, because it leads to the formation of carcinogenic nitrosamines. The amount of nitrite (10-40 ppm) associated with the cured colour and flavour is fairly harmless, and it is the larger amount, (100-200 ppm) added to preserve the meat, which is potentially harmful. This article reviews various preservatives which can be used in combination with low concentrations of nitrate. The authors consider that the use of lactate, of alternatively radiation sterilization, offers the best safe alternative to nitrate

  19. Hydrogen ion (Ph), ammonia, dissolved oxygen and nitrite ...

    African Journals Online (AJOL)

    Hydrogen ion (pH), dissolved oxygen, ammonia and nitrite concentrations were studied monthly in two systems (re-circulatory and semi-intensive of 3 m2 sizes) each for six months. The systems were each stocked with 200 g of Clarias gariepinus fingerlings. Results showed that all parameters were within acceptable limits ...

  20. In-situ nitrite analysis in high level waste tanks

    International Nuclear Information System (INIS)

    O'Rourke, P.E.; Prather, W.S.; Livingston, R.R.

    1992-01-01

    The Savannah River Site produces special nuclear materials used in the defense of the United States. Most of the processes at SRS are primarily chemical separations and purifications. In-situ chemical analyses help improve the safety, efficiency and quality of these operations. One area where in situ fiberoptic spectroscopy can have a great impact is the management of high level radioactive waste. High level radioactive waste at SRS is stored in more than 50 large waste tanks. The waste exists as a slurry of nitrate salts and metal hydroxides at pH's higher than 10. Sodium Nitrite is added to the tanks as a corrosion inhibitor. In-situ fiberoptic probes are being developed to measure the nitrate, nitrite and hydroxide concentrations in both liquid and solid fractions. Nitrite levels can be measured between 0.01M and 1M in a 1mm pathlength optical cell

  1. Intragastric nitrites, nitrosamines, and bacterial overgrowth during cimetidine treatment.

    OpenAIRE

    Stockbrugger, R W; Cotton, P B; Eugenides, N; Bartholomew, B A; Hill, M J; Walters, C L

    1982-01-01

    A six week course of cimetidine (1 g/day) healed peptic ulcers in 20 of 23 patients (14 with duodenal ulcer, nine with gastric ulcer). Reduction of basal acid output by 73% and peak acid output by 36% led to a rise in concentrations of intragastric aerobic bacteria and nitrate-reducing bacteria. While the mean intragastric concentration of nitrate was unchanged by treatment, there were statistically significant rises in nitrite and N-nitrosamine concentrations. The conversion from nitrates to...

  2. Alkali solution extraction of rice residue protein isolates: Influence of alkali concentration on protein functional, structural properties and lysinoalanine formation.

    Science.gov (United States)

    Hou, Furong; Ding, Wenhui; Qu, Wenjuan; Oladejo, Ayobami Olayemi; Xiong, Feng; Zhang, Weiwei; He, Ronghai; Ma, Haile

    2017-03-01

    This study evaluated the nutrient property and safety of the rice residue protein isolates (RRPI) product (extracted by different alkali concentrations) by exploring the protein functional, structural properties and lysinoalanine (LAL) formation. The results showed that with the rising of alkali concentration from 0.03M to 0.15M, the solubility, emulsifying and foaming properties of RRPI increased at first and then descended. When the alkali concentration was greater than 0.03M, the RRPI surface hydrophobicity decreased and the content of thiol and disulfide bond, Lys and Cys significantly reduced. By the analysis of HPLC, the content of LAL rose up from 276.08 to 15,198.07mg/kg and decreased to 1340.98mg/kg crude protein when the alkali concentration increased from 0.03 to 0.09M and until to 0.15M. These results indicated that RRPI alkaline extraction concentration above 0.03M may cause severe nutrient or safety problems of protein. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. 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)

  4. Role of nitrite in the photochemical formation of radicals in the snow.

    Science.gov (United States)

    Jacobi, Hans-Werner; Kleffmann, Jörg; Villena, Guillermo; Wiesen, Peter; King, Martin; France, James; Anastasio, Cort; Staebler, Ralf

    2014-01-01

    Photochemical reactions in snow can have an important impact on the composition of the atmosphere over snow-covered areas as well as on the composition of the snow itself. One of the major photochemical processes is the photolysis of nitrate leading to the formation of volatile nitrogen compounds. We report nitrite concentrations determined together with nitrate and hydrogen peroxide in surface snow collected at the coastal site of Barrow, Alaska. The results demonstrate that nitrite likely plays a significant role as a precursor for reactive hydroxyl radicals as well as volatile nitrogen oxides in the snow. Pollution events leading to high concentrations of nitrous acid in the atmosphere contributed to an observed increase in nitrite in the surface snow layer during nighttime. Observed daytime nitrite concentrations are much higher than values predicted from steady-state concentrations based on photolysis of nitrate and nitrite indicating that we do not fully understand the production of nitrite and nitrous acid in snow. The discrepancy between observed and expected nitrite concentrations is probably due to a combination of factors, including an incomplete understanding of the reactive environment and chemical processes in snow, and a lack of consideration of the vertical structure of snow.

  5. The effect of environmental hypercapnia and size on nitrite toxicity in the striped catfish (Pangasianodon hypophthalmus)

    DEFF Research Database (Denmark)

    Hvas, Malthe; Damsgaard, Christian; Gam, Le Thi Hong

    2016-01-01

    Striped catfish (Pangasianodon hypophthalmus) are farmed intensively at high stocking densities in Vietnam where they are likely to encounter environmental hypercapnia as well as occasional high levels of aquatic nitrite. Nitrite competes with Cl- for uptake at the branchial HCO3-/Cl- exchanger, ...... the ambient concentration, while small fish did not. Small P. hypophthalmus instead had significantly higher plasma [nitrate], and haemoglobin concentrations, revealing greater capacity for detoxifying nitrite by oxidising it to nitrate.......Striped catfish (Pangasianodon hypophthalmus) are farmed intensively at high stocking densities in Vietnam where they are likely to encounter environmental hypercapnia as well as occasional high levels of aquatic nitrite. Nitrite competes with Cl- for uptake at the branchial HCO3-/Cl- exchanger...... to a reduced nitrite uptake. To assess the effect of hypercapnia on nitrite uptake, fish were cannulated in the dorsal aorta, allowing repeated blood sampling for measurements of haemoglobin derivatives, plasma ions and acid-base status during exposure to 0.9 mM nitrite alone and in combination with acute...

  6. Determination of Nitrite in Whole Blood by High-Performance Liquid Chromatography with Electrochemical Detection and a Case of Nitrite Poisoning.

    Science.gov (United States)

    Yan, Hui; Zhuo, Xiangyi; Shen, Baohua; Xiang, Ping; Shen, Min

    2016-01-01

    Although nitrite is widely used in meat processing, it is a major toxicity hazard to children and is responsible for the blue-baby syndrome. A simple and effective method to determine nitrite in whole blood has been devised using ion chromatography with suppressed conductivity detection. The blood sample was deproteinized by adding acetonitrile and purified with mini-cartridges to remove hydrophobic compounds, chloride ions, and metal ions. An aliquot of the filtrate was injected onto the ion chromatography. The retention time for nitrite was 13.8 min and the detection limit of nitrite in whole blood was 0.4 μmol/L. The calibration curve was linear (r(2) = 0.9999) over the concentration working range. The blood nitrite concentration of a victim who attempted suicide by ingesting sodium nitrite powder was determined using the present method. The basal levels for nitrite in human blood was determined with 7.1 ± 0.9 μmol/L (n = 12). © 2015 American Academy of Forensic Sciences.

  7. Nitrite toxicity assessment in Danio rerio and Poecilia reticulata

    Directory of Open Access Journals (Sweden)

    Petra Doleželová

    2011-01-01

    Full Text Available Nitrite is a natural component of the nitrogen cycle in the environment. Although it usually occurs in low concentrations, elevated concentrations caused by effluents or affected nitrification process can lead to serious health deterioration of fish. Two aquarium fish zebrafish (Danio rerio and guppy (Poecilia reticulata are recommended to use as model organisms in toxicity tests. However, their sensitivity to nitrite can differ. The aim of this study was to define acute toxicity of nitrite by the semistatic method according to OECD No. 203 (Fish, Acute toxicity test. The series of 4 acute toxicity tests was performed, with 10 fish of both species used for each concentration and for the control. The 96hLC50 NO2- value for D. rerio and P. reticulata was 242.55 ± 15.79 mg·l-1 and 30.2 ± 8.74 mg·l-1, respectively. We have proved significant difference (p D. rerio and P. reticulata. The results showed different sensitivities to nitrites in tested fish species, which could be related to species-specific branchial chloride uptake mechanism. This is the first study on this fish species.

  8. Nitrite and nitroso compounds can serve as specific catalase inhibitors.

    Science.gov (United States)

    Titov, Vladimir Yu; Osipov, Anatoly N

    2017-03-01

    We present evidence that nitrite and nitrosothiols, nitrosoamines and non-heme dinitrosyl iron complexes can reversibly inhibit catalase with equal effectiveness. Catalase activity was evaluated by the permanganatometric and calorimetric assays. This inhibition is not the result of chemical transformations of these compounds to a single inhibitor, as well as it is not the result of NO release from these substances (as NO traps have no effect on the extent of inhibition). It was found that chloride and bromide in concentration above 80 mM and thiocyanate in concentration above 20 μM enhance catalase inhibition by nitrite and the nitroso compounds more than 100 times. The inhibition degree in this case is comparable with that induced by azide. We propose that the direct catalase inhibitor is a positively charged NO-group. This group acquires a positive charge in the active center of enzyme by interaction of nitrite or nitroso compounds with some enzyme groups. Halides and thiocyanate protect the NO + group from hydration and thus increase its inhibition effect. It is probable that a comparatively low chloride concentration in many cells is the main factor to protect catalase from inhibition by nitrite and nitroso compounds.

  9. Effect of meat ingredients (sodium nitrite and erythorbate) and processing (vacuum storage and packaging atmosphere) on germination and outgrowth of Clostridium perfringens spores in ham during abusive cooling.

    Science.gov (United States)

    Redondo-Solano, Mauricio; Valenzuela-Martinez, Carol; Cassada, David A; Snow, Daniel D; Juneja, Vijay K; Burson, Dennis E; Thippareddi, Harshavardhan

    2013-09-01

    The effect of nitrite and erythorbate on Clostridium perfringens spore germination and outgrowth in ham during abusive cooling (15 h) was evaluated. Ham was formulated with ground pork, NaNO2 (0, 50, 100, 150 or 200 ppm) and sodium erythorbate (0 or 547 ppm). Ten grams of meat (stored at 5 °C for 3 or 24 h after preparation) were transferred to a vacuum bag and inoculated with a three-strain C. perfringens spore cocktail to obtain an inoculum of ca. 2.5 log spores/g. The bags were vacuum-sealed, and the meat was heat treated (75 °C, 20 min) and cooled within 15 h from 54.4 to 7.2 °C. Residual nitrite was determined before and after heat treatment using ion chromatography with colorimetric detection. Cooling of ham (control) stored for 3 and 24 h, resulted in C. perfringens population increases of 1.46 and 4.20 log CFU/g, respectively. For samples that contained low NaNO2 concentrations and were stored for 3 h, C. perfringens populations of 5.22 and 2.83 log CFU/g were observed with or without sodium erythorbate, respectively. Residual nitrite was stable (p > 0.05) for both storage times. Meat processing ingredients (sodium nitrite and sodium erythorbate) and their concentrations, and storage time subsequent to preparation of meat (oxygen content) affect C. perfringens spore germination and outgrowth during abusive cooling of ham. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Nitrite survival and nitrous oxide production of denitrifying phosphorus removal sludges in long-term nitrite/nitrate-fed sequencing batch reactors.

    Science.gov (United States)

    Wang, Yayi; Zhou, Shuai; Ye, Liu; Wang, Hong; Stephenson, Tom; Jiang, Xuxin

    2014-12-15

    Nitrite-based phosphorus (P) removal could be useful for innovative biological P removal systems where energy and carbon savings are a priority. However, using nitrite for denitrification may cause nitrous oxide (N2O) accumulation and emissions. A denitrifying nitrite-fed P removal system [Formula: see text] was successfully set up in a sequencing batch reactor (SBR) and was run for 210 days. The maximum pulse addition of nitrite to [Formula: see text] was 11 mg NO2(-)-N/L in the bulk, and a total of 34 mg NO2(-)-N/L of nitrite was added over three additions. Fluorescent in situ hybridization results indicated that the P-accumulating organisms (PAOs) abundance was 75 ± 1.1% in [Formula: see text] , approximately 13.6% higher than that in a parallel P removal SBR using nitrate [Formula: see text] . Type II Accumulibacter (PAOII) (unable to use nitrate as an electron acceptor) was the main PAOs species in [Formula: see text] , contributing 72% to total PAOs. Compared with [Formula: see text] , [Formula: see text] biomass had enhanced nitrite/free nitrous acid (FNA) endurance, as demonstrated by its higher nitrite denitrification and P uptake rates. N2O accumulated temporarily in [Formula: see text] after each pulse of nitrite. Peak N2O concentrations in the bulk for [Formula: see text] were generally 6-11 times higher than that in [Formula: see text] ; these accumulations were rapidly denitrified to nitrogen gases. N2O concentration increased rapidly in nitrate-cultivated biomass when 5 or 10 mg NO2(-)-N/L per pulse was added. Whereas, N2O accumulation did not occur in nitrite-cultivated biomass until up to 30 mg NO2(-)-N/L per pulse was added. Long-term acclimation to nitrite and pulse addition of nitrite in [Formula: see text] reduced the risk of nitrite accumulation, and mitigated N2O accumulation and emissions from denitrifying P removal by nitrite. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Evaluation of ground calcite/water heavy media cyclone suspensions for production of residual plastic concentrates.

    Science.gov (United States)

    Gent, Malcolm; Sierra, Héctor Muñiz; Menéndez, Mario; de Cos Juez, Francisco Javier

    2018-01-01

    Viable recycled residual plastic (RP) product(s) must be of sufficient quality to be reusable as a plastic or source of hydrocarbons or fuel. The varied composition and large volumes of such wastes usually requires a low cost, high through-put recycling method(s) to eliminate contaminants. Cyclone separation of plastics by density is proposed as a potential method of achieving separations of specific types of plastics. Three ground calcite separation medias of different grain size distributions were tested in a cylindrical cyclone to evaluate density separations at 1.09, 1.18 and 1.27 g/cm 3 . The differences in separation recoveries obtained with these medias by density offsets produced due to displacement of separation media solid particles within the cyclone caused by centrifugal settling is evaluated. The separation density at which 50% of the material of that density is recovered was found to increase from 0.010 to 0.026 g/cm 3 as the separation media density increased from 1.09 to 1.27 g/cm 3 . All separation medias were found to have significantly low Ep 95 values of 0.012-0.033 g/cm 3 . It is also demonstrated that the presence of an excess content of 75%) resulted in reduced separation efficiencies. It is shown that the optimum separations were achieved when the media density offset was 0.03-0.04 g/cm 3 . It is shown that effective heavy media cyclone separations of RP denser than 1.0 g/cm 3 can produce three sets of mixed plastics containing: PS and ABS/SAN at densities of >1.0-1.09 g/cm 3 ; PC, PMMA at a density of 1.09-1.18 g/cm 3 ; and PVC and PET at a density of >1.27 g/cm 3 . Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Estimation of nitrite in source-separated nitrified urine with UV spectrophotometry.

    Science.gov (United States)

    Mašić, Alma; Santos, Ana T L; Etter, Bastian; Udert, Kai M; Villez, Kris

    2015-11-15

    Monitoring of nitrite is essential for an immediate response and prevention of irreversible failure of decentralized biological urine nitrification reactors. Although a few sensors are available for nitrite measurement, none of them are suitable for applications in which both nitrite and nitrate are present in very high concentrations. Such is the case in collected source-separated urine, stabilized by nitrification for long-term storage. Ultraviolet (UV) spectrophotometry in combination with chemometrics is a promising option for monitoring of nitrite. In this study, an immersible in situ UV sensor is investigated for the first time so to establish a relationship between UV absorbance spectra and nitrite concentrations in nitrified urine. The study focuses on the effects of suspended particles and saturation on the absorbance spectra and the chemometric model performance. Detailed analysis indicates that suspended particles in nitrified urine have a negligible effect on nitrite estimation, concluding that sample filtration is not necessary as pretreatment. In contrast, saturation due to very high concentrations affects the model performance severely, suggesting dilution as an essential sample preparation step. However, this can also be mitigated by simple removal of the saturated, lower end of the UV absorbance spectra, and extraction of information from the secondary, weaker nitrite absorbance peak. This approach allows for estimation of nitrite with a simple chemometric model and without sample dilution. These results are promising for a practical application of the UV sensor as an in situ nitrite measurement in a urine nitrification reactor given the exceptional quality of the nitrite estimates in comparison to previous studies. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Crosstalk between nitrite, myoglobin and reactive oxygen species to regulate vasodilation under hypoxia.

    Directory of Open Access Journals (Sweden)

    Matthias Totzeck

    Full Text Available The systemic response to decreasing oxygen levels is hypoxic vasodilation. While this mechanism has been known for more than a century, the underlying cellular events have remained incompletely understood. Nitrite signaling is critically involved in vessel relaxation under hypoxia. This can be attributed to the presence of myoglobin in the vessel wall together with other potential nitrite reductases, which generate nitric oxide, one of the most potent vasodilatory signaling molecules. Questions remain relating to the precise concentration of nitrite and the exact dose-response relations between nitrite and myoglobin under hypoxia. It is furthermore unclear whether regulatory mechanisms exist which balance this interaction. Nitrite tissue levels were similar across all species investigated. We then investigated the exact fractional myoglobin desaturation in an ex vivo approach when gassing with 1% oxygen. Within a short time frame myoglobin desaturated to 58±12%. Given that myoglobin significantly contributes to nitrite reduction under hypoxia, dose-response experiments using physiological to pharmacological nitrite concentrations were conducted. Along all concentrations, abrogation of myoglobin in mice impaired vasodilation. As reactive oxygen species may counteract the vasodilatory response, we used superoxide dismutase and its mimic tempol as well as catalase and ebselen to reduce the levels of reactive oxygen species during hypoxic vasodilation. Incubation of tempol in conjunction with catalase alone and catalase/ebselen increased the vasodilatory response to nitrite. Our study shows that modest hypoxia leads to a significant nitrite-dependent vessel relaxation. This requires the presence of vascular myoglobin for both physiological and pharmacological nitrite levels. Reactive oxygen species, in turn, modulate this vasodilation response.

  14. Excessive nitrite affects zebrafish valvulogenesis through yielding too much NO signaling.

    Directory of Open Access Journals (Sweden)

    Junbo Li

    Full Text Available Sodium nitrite, a common food additive, exists widely not only in the environment but also in our body. Excessive nitrite causes toxicological effects on human health; however, whether it affects vertebrate heart valve development remains unknown. In vertebrates, developmental defects of cardiac valves usually lead to congenital heart disease. To understand the toxic effects of nitrite on valvulogenesis, we exposed zebrafish embryos with different concentrations of sodium nitrite. Our results showed that sodium nitrite caused developmental defects of zebrafish heart dose dependently. It affected zebrafish heart development starting from 36 hpf (hour post fertilization when heart initiates looping process. Comprehensive analysis on the embryos at 24 hpf and 48 hpf showed that excessive nitrite did not affect blood circulation, vascular network, myocardium and endocardium development. But development of endocardial cells in atrioventricular canal (AVC of the embryos at 48 hpf was disrupted by too much nitrite, leading to defective formation of primitive valve leaflets at 76 hpf. Consistently, excessive nitrite diminished expressions of valve progenitor markers including bmp4, has2, vcana and notch1b at 48 hpf. Furthermore, 3', 5'-cyclic guanosine monophosphate (cGMP, downstream of nitric oxide (NO signaling, was increased its level significantly in the embryos exposed with excessive nitrite and microinjection of soluble guanylate cyclase inhibitor ODQ (1H-[1], [2], [4]Oxadiazolo[4,3-a] quinoxalin-1-one, an antagonist of NO signaling, into nitrite-exposed embryos could partly rescue the cardiac valve malformation. Taken together, our results show that excessive nitrite affects early valve leaflet formation by producing too much NO signaling.

  15. Hybrid-renewable processes for biofuels production: concentrated solar pyrolysis of biomass residues

    Energy Technology Data Exchange (ETDEWEB)

    George, Anthe [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Geier, Manfred [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Dedrick, Daniel E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-10-01

    The viability of thermochemically-derived biofuels can be greatly enhanced by reducing the process parasitic energy loads. Integrating renewable power into biofuels production is one method by which these efficiency drains can be eliminated. There are a variety of such potentially viable "hybrid-renewable" approaches; one is to integrate concentrated solar power (CSP) to power biomass-to-liquid fuels (BTL) processes. Barriers to CSP integration into BTL processes are predominantly the lack of fundamental kinetic and mass transport data to enable appropriate systems analysis and reactor design. A novel design for the reactor has been created that can allow biomass particles to be suspended in a flow gas, and be irradiated with a simulated solar flux. Pyrolysis conditions were investigated and a comparison between solar and non-solar biomass pyrolysis was conducted in terms of product distributions and pyrolysis oil quality. A novel method was developed to analyse pyrolysis products, and investigate their stability.

  16. An effort for reducing Nitrite in the partition process by using Diphenyl Thio Urea

    International Nuclear Information System (INIS)

    Mashudi; Busron-Masduki; Damunir; Mujianto

    1996-01-01

    The existence of nitrite in the process of U-Pu partition will disturb the partition process. In addition to the reoxidization of Pu 3+ to Pu 4+ , nitrite will also react with reductor. Both reactions are not expected, so that the nitrite ion in the partition process must be eliminated or reduced as much as possible. An experiment on the nitrite elimination in the partition process was done by reacting nitrite with diphenyl thio urea. The experiment result showed that the optimum condition was achieved at a contact time of 6 minutes, at the concentration of 0.004 N (300% stoichiometric), and the elimination result was 90%. This result is competitive enough if compared with hydrazine hydroxide or amido sulphonic acid, where the contact time is 6 minutes, the excess of both reactants are 200% and 300%, and the elimination results are 60% and 50% respectively

  17. Controls of nitrite oxidation in ammonia-removing biological air filters

    DEFF Research Database (Denmark)

    Juhler, Susanne; Ottosen, Lars Ditlev Mørck; Nielsen, Lars Peter

    2008-01-01

    in accumulation of nitrate rather than nitrite and a significant decline in pH. As a consequence, ammonia is removed more efficiently, but heterotrophic oxidation of odorous compounds might be inhibited.  To identify the controlling mechanisms of nitrite oxidation, full-scale biological air filters were...... activity resulting in a lowered pH and thus a decreased FA concentration, promoting further growth of NOB. Yet, in some cases a situation with a nitrate-to-nitrite ratio of 1 and moderate pH remained stable even under varying air load and water supply, suggesting that additional mechanisms were involved......In biological air filters ammonia is removed due to the action of Ammonia Oxidizing Bacteria (AOB) resulting in nitrite accumulation exceeding 100 mM. Among filters treating exhaust air from pig facilities successful establishment of Nitrite Oxidizing Bacteria (NOB) sometimes occurs, resulting...

  18. 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..

  19. Wet high-intensity magnetic separation for the concentration of Witwatersrand gold-uranium ores and residues

    International Nuclear Information System (INIS)

    Corrans, I.J.; Levin, J.

    1979-01-01

    Wet high-intensity magnetic separation (WHIMS) for the concentration of gold and uranium was tested on many Witwatersrand cyanidation residues, and on some ores and flotation tailings. The results varied, but many indicated recoveries of over 60 per cent of the gold and uranium. The main source of loss is the inefficiency of WHIMS for material of smaller particle size than 20μm. The recoveries in the continuous tests were lower than those in the batch tests. The continuous tests indicated an operational difficulty that could be experienced in practice, namely the tendency for wood chips and ferromagnetic particles to block the matrix of the separator. It was decided that a solution to the problem lies in the modification of the separator to allow continuous removal of the matrix for cleaning. A system has been developed for this purpose and is being demonstrated on a pilot-plant scale. Promising results were obtained in tests on a process that combines a coarse grind, gravity concentration, and WHIMS. In the gravity-concentration step, considerable recoveries, generally over 50 per cent, of high-grade pyrite were obtained, together with high recoveries of gold and moderate, but possibly important, recoveries of uranium. A simple model describing the operation of the WHIMS machine in terms of the operating parameters is described. This should reduce the amount of empirical testwork required for the optimization of operating conditions and should provide a basis for scale-up calculations. The economics of the WHIMS process is discussed [af

  20. First report of the concentrations and implications of DDT residues in chicken eggs from a malaria-controlled area.

    Science.gov (United States)

    Bouwman, Hindrik; Bornman, Riana; van Dyk, Cobus; Barnhoorn, Irene

    2015-10-01

    In malaria-endemic areas, where DDT is still used for vector control by indoor residual spraying (IRS), the concentrations of DDT in human blood and breast milk are high, and there are indications of human health impacts. To identify the possible avenues of exposure reduction, we created the concept of a Total Homestead Environment Approach (THEA). THEA characterizes the interactions between DDT, humans, and the biota within and around homesteads. One dietary route of human exposure and uptake of DDT, namely, chicken egg consumption, has to our knowledge never been studied. The ΣDDT in eggs from a DDT-sprayed village ranged between 5200 and 48,000 ng/g wm (wet mass), with a median of 11,000 ng/g wm. On a lipid mass-basis (lm), the mean ΣDDT for eggs from the sprayed village was 100,000 ng/g lm. The maximum egg concentration observed was three orders of magnitude higher than the median. The acceptable daily intake (ADI) was not exceeded based on the consumption of three eggs per week for a 60 kg person. This equates to an intake of 0.089 g DDT per person per year. Chicken egg consumption is therefore a possible target for exposure reduction, probably best achieved by reducing the DDT concentrations in soils. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Food sources of nitrates and nitrites: the physiologic context for potential health benefits.

    Science.gov (United States)

    Hord, Norman G; Tang, Yaoping; Bryan, Nathan S

    2009-07-01

    The presence of nitrates and nitrites in food is associated with an increased risk of gastrointestinal cancer and, in infants, methemoglobinemia. Despite the physiologic roles for nitrate and nitrite in vascular and immune function, consideration of food sources of nitrates and nitrites as healthful dietary components has received little attention. Approximately 80% of dietary nitrates are derived from vegetable consumption; sources of nitrites include vegetables, fruit, and processed meats. Nitrites are produced endogenously through the oxidation of nitric oxide and through a reduction of nitrate by commensal bacteria in the mouth and gastrointestinal tract. As such, the dietary provision of nitrates and nitrites from vegetables and fruit may contribute to the blood pressure-lowering effects of the Dietary Approaches to Stop Hypertension (DASH) diet. We quantified nitrate and nitrite concentrations by HPLC in a convenience sample of foods. Incorporating these values into 2 hypothetical dietary patterns that emphasize high-nitrate or low-nitrate vegetable and fruit choices based on the DASH diet, we found that nitrate concentrations in these 2 patterns vary from 174 to 1222 mg. The hypothetical high-nitrate DASH diet pattern exceeds the World Health Organization's Acceptable Daily Intake for nitrate by 550% for a 60-kg adult. These data call into question the rationale for recommendations to limit nitrate and nitrite consumption from plant foods; a comprehensive reevaluation of the health effects of food sources of nitrates and nitrites is appropriate. The strength of the evidence linking the consumption of nitrate- and nitrite-containing plant foods to beneficial health effects supports the consideration of these compounds as nutrients.

  2. Dietary Nitrite: from menace to marvel

    Directory of Open Access Journals (Sweden)

    Nathan S. Bryan

    2016-11-01

    Full Text Available The health benefits of nitrite are now indisputable when administered in a clinical setting for specific diseases. Currently, most published reports identify the production of nitric oxide (NO as the mechanism of action for nitrite. Basic science, in addition to clinical studies, demonstrate that nitrite and/or nitrate cannot restore NO homeostasis as an endothelium independent source of NO that may be a redundant system for endogenous NO production. Nitrate must first be reduced to nitrite by oral commensal bacteria; nitrite can then be further reduced to NO along the physiological oxygen gradient. But despite decades of rigorous research on sodium nitrate’s safety and efficacy as a curing agent, sodium nitrite is still regarded by many as a toxic undesirable food additive. However, research within the biomedical science community has revealed enormous therapeutic benefits of nitrite which are being developed as novel therapies for conditions associated with nitric oxide insufficiency. Thus, this review will highlight the fundamental biochemistry of nitrite in human physiology and provide evidence that nitrite be considered an essential nutrient. Foods or diets enriched with nitrite can have profound positive health benefits.

  3. MONITORING KADAR NITRIT DAN NITRAT PADA AIR SUMUR DI DAERAH CATUR TUNGGAL YOGYAKARTA DENGAN METODE SPEKTROFOTOMETRI UV-VIS (Monitoring of Nitrite and Nitrate Content in Ground Water of Catur Tunggal Region of Yogyakarta by UV-VIS Spectrophotometry

    Directory of Open Access Journals (Sweden)

    Setiowati Setiowati

    2016-07-01

    Full Text Available ABSTRAK Metode analisis nitrit dan nitrat perlu dikembangkan untuk memonitor kualitas air minum. Kualitas air sumur untuk parameter nitrit dan nitrat dipengaruhi oleh kondisi lingkungan dan kedalaman air sumur.Penelitian ini bertujuan menganalisis nitrit dan nitrat menggunakan asam p-aminobenzoat (PABA pada air sumur di daerah perkotaan Yogyakarta. Analisis nitrit didasarkan pada reaksi antara ion nitrit dengan PABA yang membentuk senyawa azo dengan panjang gelombang maksimum 546 nm. Kedalaman air sumur di daerah Catur Tunggal rata-rata > 10 m. Kadar nitrit dan nitrat pada air sumur adalah 0,05-0,09 dan 8,22-36,58 mg/L. Kadar nitrit dan nitrat tersebut memenuhi baku mutu dan aman untuk dikonsumsi. Konsentrasi nitrit dan nitrat pada air RO adalah 0,05 dan 2,72-59,57 mg/L. Kadar nitrit pada air RO tidak memenuhi baku mutu sedangkan kadar nitrat memenuhi baku mutu kecuali RO 5. ABSTRACT The method for analysis nitrite and nitrate had to developed to monitor the drinking water quality. The well water quality, especially for nitrite and nitrate were influenced by environmental conditions and depth of well. This study aims to analyze nitrite and nitrate using p-aminobenzoic acid (PABA in ground water at urban areas of Yogyakarta. The analysis was based on the reaction between nitrite ions with PABA which form azo compounds with a maximum wavelength of 546 nm. The depth of wells at Catur Tunggal were more than 10 m. Concentration of nitrite and nitrate in well water were 0.05 to 0.09 and 8.22 to 36.58 mg / L. The concentrations met the standard for drinking water quality and was safe for consumption. The concentration of nitrite and nitrate in reverse osmosis (RO water were 0.05 and 2.72 to 59.57 mg / L. The concentration of nitrite did not meet the standard for drinking water quality while the concentration of nitrate met the standard for drinking water quality except RO 5.

  4. 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

  5. Role of blood and vascular smooth muscle in the vasoactivity of nitrite

    Science.gov (United States)

    Liu, Taiming; Schroeder, Hobe J.; Barcelo, Lisa; Bragg, Shannon L.; Terry, Michael H.; Wilson, Sean M.; Power, Gordon G.

    2014-01-01

    Recent evidence from humans and rats indicates that nitrite is a vasodilator under hypoxic conditions by reacting with metal-containing proteins to produce nitric oxide (NO). We tested the hypothesis that near-physiological concentrations of nitrite would produce vasodilation in a hypoxia- and concentration-dependent manner in the hind limb of sheep. Anesthetized sheep were instrumented to measure arterial blood pressure and femoral blood flows continuously in both hind limbs. Nitrite was infused into one femoral artery to raise the nitrite concentration in the femoral vein by 10 to 15-fold while the sheep breathed 50%, 14% or 12% oxygen in inspired air. In contrast to reports in humans and rats, the nitrite infusion had no measurable effect on mean femoral blood flows or vascular conductances, regardless of inspired O2 levels. In vitro experiments showed no significant difference in the release of NO from nitrite in sheep and human red blood cells. Further experiments demonstrated nitrite is converted to NO in rat artery homogenates faster than sheep arteries, and that this source of NO production is attenuated in the presence of a heme oxidizer. Finally, western blots indicate that concentrations of the heme-containing protein cytoglobin, but not myoglobin, are markedly lower in sheep arteries compared with rats. Overall, the results demonstrate that nitrite is not a physiological vasodilator in sheep. This is likely due to a lack of conversion of nitrite to NO within the vascular smooth muscle, perhaps due to deficient amounts of the heme-containing protein cytoglobin. PMID:25108012

  6. Boletus edulis Nitrite Reductase Reduces Nitrite Content of Pickles and Mitigates Intoxication in Nitrite-intoxicated Mice.

    Science.gov (United States)

    Zhang, Weiwei; Tian, Guoting; Feng, Shanshan; Wong, Jack Ho; Zhao, Yongchang; Chen, Xiao; Wang, Hexiang; Ng, Tzi Bun

    2015-10-08

    Pickles are popular in China and exhibits health-promoting effects. However, nitrite produced during fermentation adversely affects health due to formation of methemoglobin and conversion to carcinogenic nitrosamine. Fruiting bodies of the mushroom Boletus edulis were capable of inhibiting nitrite production during pickle fermentation. A 90-kDa nitrite reductase (NiR), demonstrating peptide sequence homology to fungal nitrite reductase, was isolated from B. edulis fruiting bodies. The optimum temperature and pH of the enzyme was 45 °C and 6.8, respectively. B. edulis NiR was capable of prolonging the lifespan of nitrite-intoxicated mice, indicating that it had the action of an antidote. The enzyme could also eliminate nitrite from blood after intragastric administration of sodium nitrite, and after packaging into capsule, this nitrite-eliminating activity could persist for at least 120 minutes thus avoiding immediate gastric degradation. B. edulis NiR represents the first nitrite reductase purified from mushrooms and may facilitate subsequent applications.

  7. Visceral organ weights, digestion and carcass characteristics of beef bulls differing in residual feed intake offered a high concentrate diet.

    Science.gov (United States)

    Fitzsimons, C; Kenny, D A; McGee, M

    2014-06-01

    This study examined the relationship of residual feed intake (RFI) with digestion, body composition, carcass traits and visceral organ weights in beef bulls offered a high concentrate diet. Individual dry matter (DM) intake (DMI) and growth were measured in a total of 67 Simmental bulls (mean initial BW 431 kg (s.d.=63.7)) over 3 years. Bulls were offered concentrates (860 g/kg rolled barley, 60 g/kg soya bean meal, 60 g/kg molasses and 20 g/kg minerals per vitamins) ad libitum plus 0.8 kg grass silage DM daily for 105 days pre-slaughter. Ultrasonic muscle and fat depth, body condition score (BCS), muscularity score, skeletal measurements, blood metabolites, rumen fermentation and total tract digestibility (indigestible marker) were determined. After slaughter, carcasses and perinephric and retroperitoneal fat were weighed, carcasses were graded for conformation and fat score and weight of non-carcass organs, liver, heart, kidneys, lungs, gall bladder, spleen, reticulo-rumen full and empty and intestines full, were determined. The residuals of the regression of DMI on average daily gain (ADG), mid-test metabolic BW (BW0.75) and the fixed effect of year, using all animals, were used to compute individual RFI coefficients. Animals were ranked on RFI and assigned to high (inefficient), medium or low groupings. Overall mean ADG and daily DMI were 1.6 kg (s.d.=0.36) and 9.4 kg (s.d.=1.16), respectively. High RFI bulls consumed 7 and 14% more DM than medium and low RFI bulls, respectively (P0.05) for ADG, BW, BCS, skeletal measurements, muscularity scores, ultrasonic measurements, carcass weight, perinephric and retroperitoneal fat weight, kill-out proportion and carcass conformation and fat score. However, regression analysis indicated that a 1 kg DM/day increase in RFI was associated with a decrease in kill-out proportion of 20 g/kg (Pcarcass conformation of 0.74 units (Pcarcass organs did not differ (P>0.05) between RFI groups except for the empty weight of reticulo

  8. Nitrite oxidizing bacteria for water treatment in coastal aquaculture system

    Science.gov (United States)

    Noorak, S.; Rakkhiaw, S.; Limjirakhajornt, K.; Uppabullung, A.; Keawtawee, T.; Sangnoi, Y.

    2018-04-01

    This research aimed to isolate and characterize nitrite oxidizing bacteria and to study their capability for water quality improvement. Fourteen strains of bacteria with nitrite-oxidizing character were isolated after 21 days of enrichment in Pep-Beef-NOB medium contained NaNO2. Two strains, SF-1 and SF-5, showed highest nitrite removal rate for 42.42% and 37.2%, respectively. These strains were determined an efficiency of open-system wastewater treatment for 14 days. The results showed that control, SF-1 and SF-5 had remove ammonia from day 1 to day 6. At the end of the study, ammonia was removed by the control, SF-1 and SF-5 for 81.27%, 70.1% and 69.82%, respectively. Nitrite concentration was lowest at day 8 with removal rate of 98.73%, 98.3% and 97.24% from control, SF-1 and SF-5, respectively. However, nitrite concentration in control experiment was increased again at day 11 whereas in SF-1 and SF-5 were increased at day 13. Chemical Oxygen Demand (COD) was decreased by 77.78%, 73.50% and 78.63% in the control, SF-1 and SF-5, respectively. Biological Oxygen Demand (BOD) in the control, SF-1 and SF-5 were reduced by 85.92%, 79.53% and 82.09%, respectively. Based on 16S rRNA gene, SF-1 and SF-5 were identified as Bacillus vietnamensis and B. firmus, respectively.

  9. Ammonia and nitrite oxidation in the Eastern Tropical North Pacific

    Science.gov (United States)

    Peng, Xuefeng; Fuchsman, Clara A.; Jayakumar, Amal; Oleynik, Sergey; Martens-Habbena, Willm; Devol, Allan H.; Ward, Bess B.

    2015-12-01

    Nitrification plays a key role in the marine nitrogen (N) cycle, including in oceanic oxygen minimum zones (OMZs), which are hot spots for denitrification and anaerobic ammonia oxidation (anammox). Recent evidence suggests that nitrification links the source (remineralized organic matter) and sink (denitrification and anammox) of fixed N directly in the steep oxycline in the OMZs. We performed shipboard incubations with 15N tracers to characterize the depth distribution of nitrification in the Eastern Tropical North Pacific (ETNP). Additional experiments were conducted to investigate photoinhibition. Allylthiourea (ATU) was used to distinguish the contribution of archaeal and bacterial ammonia oxidation. The abundance of archaeal and β-proteobacterial ammonia monooxygenase gene subunit A (amoA) was determined by quantitative polymerase chain reaction. The rates of ammonia and nitrite oxidation showed distinct subsurface maxima, with the latter slightly deeper than the former. The ammonia oxidation maximum coincided with the primary nitrite concentration maximum, archaeal amoA gene maximum, and the subsurface nitrous oxide maximum. Negligible rates of ammonia oxidation were found at anoxic depths, where high rates of nitrite oxidation were measured. Archaeal amoA gene abundance was generally 1 to 2 orders of magnitude higher than bacterial amoA gene abundance, and inhibition of ammonia-oxidizing bacteria with 10 μM ATU did not affect ammonia oxidation rates, indicating the dominance of archaea in ammonia oxidation. These results depict highly dynamic activities of ammonia and nitrite oxidation in the oxycline of the ETNP OMZ.

  10. Formation of nitrous oxide in a gradient of oxygenation and nitrogen loading rate during denitrification of nitrite and nitrate

    Energy Technology Data Exchange (ETDEWEB)

    Gong, You-Kui; Peng, Yong-Zhen [School of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100022 (China); Yang, Qing, E-mail: gykren@163.com [School of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100022 (China); Wu, Wei-Min [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090 (China); Wang, Shu-Ying [School of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100022 (China)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer The correlation of DO to N{sub 2}O emission under denitrification via nitrite was confirmed. Black-Right-Pointing-Pointer The higher nitrite ratio in NO{sub x} (nitrite and nitrate) caused the more N{sub 2}O emission. Black-Right-Pointing-Pointer Reactor feed mode and nitrite loading rate had significant impact on N{sub 2}O emission which was related to nitrite level. - Abstract: Nitrous oxide (N{sub 2}O) emission has been observed during denitrification of nitrate via nitrite as intermediate. With a laboratory-scale reactor (2.4 L), the N{sub 2}O emission was characterized under a gradient of DO concentration from 0 to 0.7 mg/L, different ratio of nitrite versus nitrate and different nitrite feed mode. The N{sub 2}O emission was influenced by the level of dissolved oxygen (DO) and nitrite accumulation. The higher DO level and the higher ratio of nitrite versus nitrate resulted in the higher N{sub 2}O emission. Using nitrite as sole electron acceptor at the same loading rate, the sequence of N{sub 2}O emission with three different feed modes was: pulse > step-wise > continuous feed. The N{sub 2}O emitted in pulse feed reactors was 3.1-4.2 and 8.2-11.7 folds of that in the step-wise feed and continuous feed reactors, respectively. With continuous feed mode, the impact of DO concentration on the mass of N{sub 2}O emitted was limited while the higher N{sub 2}O emission occurred at the higher nitrite loading rate.

  11. Role of xanthine oxidoreductase in the anti-thrombotic effects of nitrite in rats in vivo.

    Science.gov (United States)

    Kramkowski, K; Leszczynska, A; Przyborowski, K; Kaminski, T; Rykaczewska, U; Sitek, B; Zakrzewska, A; Proniewski, B; Smolenski, R T; Chabielska, E; Buczko, W; Chlopicki, S

    2016-01-01

    The mechanisms underlying nitrite-induced effects on thrombosis and hemostasis in vivo are not clear. The goal of the work described here was to investigate the role of xanthine oxidoreductase (XOR) in the anti-platelet and anti-thrombotic activities of nitrite in rats in vivo. Arterial thrombosis was induced electrically in rats with renovascular hypertension by partial ligation of the left renal artery. Sodium nitrite (NaNO2, 0.17 mmol/kg twice daily for 3 days, p.o) was administered with or without one of the XOR-inhibitors: allopurinol (ALLO) and febuxostat (FEB) (100 and 5 mg/kg, p.o., for 3 days). Nitrite treatment (0.17 mmol/kg), which was associated with a significant increase in NOHb, nitrite/nitrate plasma concentration, resulted in a substantial decrease in thrombus weight (TW) (0.48 ± 0.03 mg vs. vehicle [VEH] 0.88 ± 0.08 mg, p < 0.001) without a significant hypotensive effect. The anti-thrombotic effect of nitrite was partially reversed by FEB (TW = 0.63 ± 0.06 mg, p < 0.05 vs. nitrites), but not by ALLO (TW = 0.43 ± 0.02 mg). In turn, profound anti-platelet effect of nitrite measured ex vivo using collagen-induced whole-blood platelet aggregation (70.5 ± 7.1% vs. VEH 100 ± 4.5%, p < 0.05) and dynamic thromboxaneB2 generation was fully reversed by both XOR-inhibitors. In addition, nitrite decreased plasminogen activator inhibitor-1 concentration (0.47 ± 0.13 ng/ml vs. VEH 0.62 ± 0.04 ng/ml, p < 0.05) and FEB/ALLO reversed this effect. In vitro the anti-platelet effect of nitrite (1 mM) was reversed by FEB (0.1 mM) under hypoxia (0.5%O2) and normoxia (20%O2). Nitrite treatment had no effect on coagulation parameters. In conclusion, the nitrite-induced anti-platelet effect in rats in vivo is mediated by XOR, but XOR does not fully account for the anti-thrombotic effects of nitrite.

  12. Solubilities of sodium nitrate, sodium nitrite, and sodium aluminate in simulated nuclear waste

    International Nuclear Information System (INIS)

    Reynolds, D.A.; Herting, D.L.

    1984-09-01

    Solubilities were determined for sodium nitrate, sodium nitrite, and sodium aluminate in synthetic nuclear waste liquor. Solubilities were determined as a function of temperature and solution composition (concentrations of sodium hydroxide, sodium nitrate, sodium nitrite, and sodium aluminate). Temperature had the greatest effect on the solubilities of sodium nitrate and sodium nitrite and a somewhat lesser effect on sodium aluminate solubility. Hydroxide had a great effect on the solubilities of all three salts. Other solution components had minor effects. 2 references, 8 figures, 11 tables

  13. Stress Corrosion Cracking of an Austenitic Stainless Steel in Nitrite-Containing Chloride Solutions

    Directory of Open Access Journals (Sweden)

    R. K. Singh Raman

    2014-12-01

    Full Text Available This article describes the susceptibility of 316L stainless steel to stress corrosion cracking (SCC in a nitrite-containing chloride solution. Slow strain rate testing (SSRT in 30 wt. % MgCl2 solution established SCC susceptibility, as evidenced by post-SSRT fractography. Addition of nitrite to the chloride solution, which is reported to have inhibitive influence on corrosion of stainless steels, was found to increase SCC susceptibility. The susceptibility was also found to increase with nitrite concentration. This behaviour is explained on the basis of the passivation and pitting characteristics of 316L steel in chloride solution.

  14. Concentrations and dissipation of difenoconazole and fluxapyroxad residues in apples and soil, determined by ultrahigh-performance liquid chromatography electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    He, Min; Jia, Chunhong; Zhao, Ercheng; Chen, Li; Yu, Pingzhong; Jing, Junjie; Zheng, Yongquan

    2016-03-01

    A new combined difenoconazole and fluxapyroxad fungicide formulation, as an 11.7 % suspension concentrate (SC), has been introduced as part of a resistance management strategy. The dissipation of difenoconazole and fluxapyroxad applied to apples and the residues remaining in the apples were determined. The 11.7 % SC was sprayed onto apple trees and soil in Beijing, Shandong, and Anhui provinces, China, at an application rate of 118 g a.i. ha(-1), then the dissipation of difenoconazole and fluxapyroxad was monitored. The residual difenoconazole and fluxapyroxad concentrations were determined by ultrahigh-performance liquid chromatography tandem mass spectrometry. The difenoconazole half-lives in apples and soil were 6.2-9.5 and 21.0-27.7 days, respectively. The fluxapyroxad half-lives in apples and soil were 9.4-12.6 and 10.3-36.5 days, respectively. Difenoconazole and fluxapyroxad residues in apples and soil after the 11.7 % SC had been sprayed twice and three times, with 10 days between applications, at 78 and 118 g a.i. ha(-1) were measured. Representative apple and soil samples were collected after the last treatment, at preharvest intervals of 14, 21, and 28 days. The difenoconazole residue concentrations in apples and soil were 0.002-0.052 and 0.002-0.298 mg kg(-1), respectively. The fluxapyroxad residue concentrations in apples and soil were 0.002-0.093 and 0.008-1.219 mg kg(-1), respectively. The difenoconazole and fluxapyroxad residue concentrations in apples were lower than the maximum residue limits (0.5 and 0.8 mg kg(-1), respectively). An application rate of 78 g a.i. ha(-1) is therefore recommended to ensure that treated apples can be considered safe for humans to consume.

  15. Evaluation of the Intake of Nitrate, Nitrite, Nitrosodiethylamine and Nitrosodimethylamine by Food Consumption

    Directory of Open Access Journals (Sweden)

    Liliana Avasilcai

    2014-12-01

    Full Text Available The aim of the present study was the evaluation of nitrate, nitrite, nitrosodiethylamine (NDEA and nitrosodimethylamine (NDMA intake by food consumption. We determined concentrations of nitrates, nitrites in 102 food samples (40 meat products, 15 fermented cheese, 25 vegetables, 22 fruits and the concentration NDEA, NDMA in 40 meat products. Nitrates and nitrites were determined using Peter-Griess method; nitrosamines were quantified by HPLC with UV detection.  We designed vegetalian, vegetarian and conventional diets of about 2500 kcal/day.  Based of the values found, we calculated the intake of nitrates, nitrites and nitrosamines. The obtained values fits to WHO’s recommendations, except for vegetalian and conventional diet, in which the nitrate content was 3,46 respectively 1,64 times higher than the acceptable daily intake (157 mg NO3-/day.

  16. Fatal methemoglobinemia caused by liniment solutions containing sodium nitrite.

    Science.gov (United States)

    Saito, T; Takeichi, S; Yukawa, N; Osawa, M

    1996-01-01

    We describe a case of fatal methemoglobinemia (MetHb-emia) resulting from application of liniment solution containing large quantities of sodium nitrite. As a remedial treatment of atopic dermatitis, the liniment solution was applied all over the boy's body. Autopsy findings showed no significant macroscopic or microscopic findings except blood tinted chocolate brown color and chronic atopic dermatitis over the whole surface of the body. Quantitation of the methemoglobin (MetHb) in the blood was performed using spectrophotometer; MetHb concentration of the blood was 76%. Ion chromatographic determination revealed a nitrite concentration of 1 mg/L in the serum. Such a liniment solution is not authorized by the Ministry of Public Welfare.

  17. Nitrite-Mediated Hypoxic Vasodilation Predicted from Mathematical Modeling and Quantified from in Vivo Studies in Rat Mesentery

    Directory of Open Access Journals (Sweden)

    Donald G. Buerk

    2017-12-01

    Full Text Available Nitric oxide (NO generated from nitrite through nitrite reductase activity in red blood cells has been proposed to play a major role in hypoxic vasodilation. However, we have previously predicted from mathematical modeling that much more NO can be derived from tissue nitrite reductase activity than from red blood cell nitrite reductase activity. Evidence in the literature suggests that tissue nitrite reductase activity is associated with xanthine oxidoreductase (XOR and/or aldehyde oxidoreductase (AOR. We investigated the role of XOR and AOR in nitrite-mediated vasodilation from computer simulations and from in vivo exteriorized rat mesentery experiments. Vasodilation responses to nitrite in the superfusion medium bathing the mesentery equilibrated with 5% O2 (normoxia or zero O2 (hypoxia at either normal or acidic pH were quantified. Experiments were also conducted following intraperitoneal (IP injection of nitrite before and after inhibiting XOR with allopurinol or inhibiting AOR with raloxifene. Computer simulations for NO and O2 transport using reaction parameters reported in the literature were also conducted to predict nitrite-dependent NO production from XOR and AOR activity as a function of nitrite concentration, PO2 and pH. Experimentally, the largest arteriolar responses were found with nitrite >10 mM in the superfusate, but no statistically significant differences were found with hypoxic and acidic conditions in the superfusate. Nitrite-mediated vasodilation with IP nitrite injections was reduced or abolished after inhibiting XOR with allopurinol (p < 0.001. Responses to IP nitrite before and after inhibiting AOR with raloxifene were not as consistent. Our mathematical model predicts that under certain conditions, XOR and AOR nitrite reductase activity in tissue can significantly elevate smooth muscle cell NO and can serve as a compensatory pathway when endothelial NO production is limited by hypoxic conditions. Our theoretical and

  18. Nitrite spray treatment to promote red color stability of vacuum packaged beef.

    Science.gov (United States)

    Song, Xiao; Cornforth, Daren; Whittier, Dick; Luo, Xin

    2015-01-01

    Sodium nitrite solutions were sprayed on select grade boneless rib (M. longissimus thoracis) and bottom round (mainly M. biceps femoris) steaks individually, to form bright red nitric oxide myoglobin (NO-Mb) in vacuum packages. Our objective was to determine the optimum level of nitrite in spray for stable raw steak redness, low or no residual nitrite, and low surface pinking (ham-like cured color) after cooking. Results showed that steaks sprayed with 100-350 ppm nitrite solutions had 3.0-3.6g weight gain and a calculated level of 1.3-5.3mg nitrite added/kg steak, but very low (color during 21 days of storage at 1°C (a*>10; chroma C*>16). Raw steak redness was less stable in round than rib. Visual scores for pinkness after cooking were low, indicating that cooked color at even the highest nitrite treatment (350 ppm) was acceptable. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    Deeb, Barbara S.; Sloan, Kenneth W.

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

  20. Music stimuli lead to increased levels of nitrite in unstimulated mixed saliva.

    Science.gov (United States)

    Jin, Luyuan; Zhang, Mengbi; Xu, Junji; Xia, Dengsheng; Zhang, Chunmei; Wang, Jingsong; Wang, Songlin

    2018-06-15

    Concentration of salivary nitrate is approximately 10-fold to that of serum. Many circumstances such as acute stress could promote salivary nitrate secretion and nitrite formation. However, whether other conditions can also be used as regulators of salivary nitrate/nitrite has not yet been explored. The present study was designed to determine the influence of exposure to different music on the salivary flow rate and nitrate secretion and nitrite formation. Twenty-four undergraduate students (12 females and 12 males) were exposed to silence, rock music, classical music or white noise respectively on four consecutive mornings. The unstimulated salivary flow rate and stimulated salivary flow rate were measured. Salivary ionic (Na + , Ca 2+ Cl - , and PO 4 3- ) content and nitrate/nitrite levels were detected. The unstimulated salivary flow rate was significantly increased after classical music exposure compared to that after silence. Salivary nitrite levels were significantly higher upon classical music and white noise stimulation than those under silence in females. However, males were more sensitive only to white noise with regard to the nitrite increase. In conclusion, this study demonstrated that classical music stimulation promotes salivary nitrite formation and an increase in saliva volume was observed. These observations may play an important role in regulating oral function.

  1. Effect of luminal or circulating nitrite on colonic ion movement in the rat

    International Nuclear Information System (INIS)

    Radcliffe, B.C.; Nance, S.H.; Deakin, E.J.; Roediger, W.E.W.

    1987-01-01

    The disposition of intravenously or luminally administered nitrite across the colonic mucosa and its effect on ion movement into or from the colon was assessed in anesthetized Porton rats using the isolated colon instilled either with sodium chloride or sodium chloride with sodium butyrate. Ionic changes in the colon after intravenous injection of 10 μmol NaNO 2 were compared with those occurring after injection of 10 μmol NaCl. After intravenous administration of nitrite, both nitrite and nitrate appeared in the colonic instillate in a ratio of 1:1. Nitrite increased chloride absorption (110%) and bicarbonate production (20%) when 40 mM butyrate was included in the instillate. Net sodium absorption, measured in the whole colon, was unchanged. Intravenous nitrite had no effect on ionic movement in the absence of butyrate. When NaNO 2 was included luminally with the sodium chloride-butyrate instillate, bicarbonate production rate increased, but sodium and chloride absorption were unaffected. Nitrite concentration in the instillate decreased during the 40-min experimental period at a rate of 0.275 nmol·min -1 ·cm -2 and nitrate appeared at a rate of 0.037 nmol·min -1 ·cm -2 . The authors conclude that nitrite stimulates bicarbonate production in the colon, probably by stimulating the oxidation by butyrate, the main source of CO 2 generation by the colonic mucosa

  2. Nitrite, nitrite alternatives, and the control of Clostridium botulinum in cured meats.

    Science.gov (United States)

    Pierson, M D; Smoot, L A

    1982-01-01

    Historically, nitrite has been a component of meat-curing additives for several centuries. In recent years the safety of nitrite as an additive in cured meats has been questioned mainly because of the possible formation of carcinogenic nitrosamines. Nitrite has many important functions in meat curing including its role in color development, flavor, antioxidant properties, and antimicrobial activity. The inhibition of Clostridium botulinum growth and toxin production is an especially important antimicrobial property of nitrite. This review discusses the effects of processing, curing ingredients (especially nitrite), and storage of cured meats in relation to the control of C. botulinum. If nitrite is eliminated from cured meats or the level of usage decreased, then alternatives for the antibotulinal function of nitrite need to be considered. Several potential alternatives including sorbates, parabens, and biological acidulants are discussed.

  3. Estimation of polycyclic aromatic hydrocarbon concentrations in the water column based on tissue residues in mussels and salmon: An equilibrium partitioning approach

    International Nuclear Information System (INIS)

    Neff, J.M.; Burns, W.A.

    1996-01-01

    Equilibrium partitioning was used to estimate concentrations of dissolved polycyclic aromatic hydrocarbons (PAHs) in the water column from PAH residues in tissues of mussels and juvenile pink salmon collected from coastal marine waters affected by the Exxon Valdez oil spill. Estimated concentrations were within factors of 2 to 5 for fish and 5 to 10 for mussels of average total dissolved and particulate PAHs measured in concurrent water samples. Temporal trends of estimated and measured water-column PAH concentrations were comparable. Water-column PAH concentrations estimated from residues in tissues of mussels (Mytilus trossulus) were higher than estimates based on residues in tissues of juvenile pink salmon (Oncorhynchus gorbuscha). Possible reasons for this difference include seasonal variations in mussel lipid content, differences in PAH uptake and depuration rates between fish and mussels, differences in how fish and mussels interact with particulate oil, and possible short exposure times for juvenile pink salmon. All of these factors may play a role. In any event, estimates of dissolved PAHs in the water column, based on PAH residues in either fish or mussel tissue, confirm that PAH concentrations generally did not exceed water quality standards for protection of marine life

  4. Detection of nitrite based on fluorescent carbon dots by the hydrothermal method with folic acid

    Science.gov (United States)

    Lin, Haitao; Ding, Liyun; Zhang, Bingyu; Huang, Jun

    2018-05-01

    A fluorescent carbon dots probe for the detection of aqueous nitrite was fabricated by a one-pot hydrothermal method, and the transmission electron microscope, X-ray diffractometer, UV-Vis absorption spectrometer and fluorescence spectrophotometer were used to study the property of carbon dots. The fluorescent property of carbon dots influenced by the concentration of aqueous nitrite was studied. The interaction between the electron-donating functional groups and the electron-accepting nitrous acid could account for the quenching effect on carbon dots by adding aqueous nitrite. The products of the hydrolysis of aqueous nitrite performed a stronger quenching effect at lower pH. The relationship between the relative fluorescence intensity of carbon dots and the concentration of nitrite was described by the Stern-Volmer equation (I0/I - 1 = 0.046[Q]) with a fine linearity (R2 = 0.99). The carbon dots-based probe provides a convenient method for the detection of nitrite concentration.

  5. Histological alterations in gills of Macrobrachium amazonicum juveniles exposed to ammonia and nitrite.

    Science.gov (United States)

    Dutra, Fabrício Martins; Rönnau, Milton; Sponchiado, Dircelei; Forneck, Sandra Carla; Freire, Carolina Arruda; Ballester, Eduardo Luis Cupertino

    2017-06-01

    Aquaculture has shown great growth in the last decades. Due to the restrictions on water use, production systems are becoming increasingly more intensive, raising concerns about the production water quality. Macrobrachium amazonicum is among the freshwater prawn species with favorable characteristics for production and possibility of intensification. Nitrogen compounds such as ammonia and nitrite affect the health of aquatic organisms since they quickly reach toxic concentrations. These compounds can also cause damage to the gill structure, leading to hypoxia in tissues, affecting acid-base balance, osmoregulation (salt absorption) and ammonia excretion, decreasing the immune capacity of the animal and, in extreme cases, cause death. The aim of this study was to assess histological changes in the gills of Macrobrachium amazonicum juveniles subjected to different concentrations of total ammonia and nitrite. The prawns were subjected to different concentrations of those compounds and their gills were removed and preserved for histological analysis. The gills were assessed for changes according to the Organ Index (I org ) and, for each change, an importance factor (w) was attributed according to the degree of reversibility and applied according to the degree of extension or frequency of the damage. The damage to the gills in the treatments with 100% mortality, both for ammonia and nitrite, corresponded to the high occurrence of progressive, regressive, circulatory, and inflammation damages. The other treatments (which caused less mortality) had mainly inflammation and regressive damages, whose occurrence increased according to the increase in ammonia and nitrite concentration. The histological analysis confirmed that the higher the total ammonia and nitrite concentrations, the larger the damages caused to the gill structure and that lower nitrite concentrations caused similar damages to those caused by higher total ammonia concentrations, which reflects the lower

  6. A coupled system of half-nitritation and ANAMMOX for mature landfill leachate nitrogen removal.

    Science.gov (United States)

    Li, Yun; Li, Jun; Zhao, Baihang; Wang, Xiujie; Zhang, Yanzhuo; Wei, Jia; Bian, Wei

    2017-09-01

    A coupled system of membrane bioreactor-nitritation (MBR-nitritation) and up-flow anaerobic sludge blanket-anaerobic ammonium oxidation (UASB-ANAMMOX) was employed to treat mature landfill leachate containing high ammonia nitrogen and low C/N. MBR-nitritation was successfully realized for undiluted mature landfill leachate with initial concentrations of 900-1500 mg/L [Formula: see text] and 2000-4000 mg/L chemical oxygen demand. The effluent [Formula: see text] concentration and the [Formula: see text] accumulation efficiency were 889 mg/L and 97% at 125 d, respectively. Half-nitritation was quickly realized by adjustment of hydraulic retention time and dissolved oxygen (DO), and a low DO control strategy could allow long-term stable operation. The UASB-ANAMMOX system showed high effective nitrogen removal at a low concentration of mature landfill leachate. The nitrogen removal efficiency was inhibited at excessive influent substrate concentration and the nitrogen removal efficiency of the system decreased as the concentration of mature landfill leachate increased. The MBR-nitritation and UASB-ANAMMOX processes were coupled for mature landfill leachate treatment and together resulted in high effective nitrogen removal. The effluent average total nitrogen concentration and removal efficiency values were 176 mg/L and 83%, respectively. However, the average nitrogen removal load decreased from 2.16 to 0.77 g/(L d) at higher concentrations of mature landfill leachate.

  7. Production and mitigation of N2O in sequentially membrane-aerated redox-stratified nitritation/anammox biofilms

    DEFF Research Database (Denmark)

    Smets, Barth F.; Pellicer i Nàcher, Carles; Thamdrup, Bo

    batch incubations with biofilm samples revealed a significant N2O assimilatory activity. Anoxic incubations with N-15 enriched nitrite, nitrate, or ammonium, in presence or absence of acetate revealed the following: a very high conversion of original nitrite or nitrate N to N2O over N2, no stimulatory......Combining partial nitritation with anaerobic ammonium oxidation maybe a cost- and energy-efficient alternative to remove reduced nitrogen from nitrogen rich waste streams. However, increased N2O emissions (upto several % of the incoming N flux) have been observed for reactors performing partial...... nitritation, which is likely due to the stimulatory effect of combined elevated nitrite and ammonium concentrations and reduced oxygen concentrations on nitrous oxide formation by ammonium oxidizing bacteria. Because increased N2O emission may be inherent to partial nitrification systems, we have explored how...

  8. Thorium, uranium and rare earth elements content in lanthanide concentrate (LC) and water leach purification (WLP) residue of Lynas advanced materials plant (LAMP)

    Science.gov (United States)

    AL-Areqi, Wadeeah M.; Majid, Amran Ab.; Sarmani, Sukiman

    2014-02-01

    Lynas Advanced Materials Plant (LAMP) has been licensed to produce the rare earths elements since early 2013 in Malaysia. LAMP processes lanthanide concentrate (LC) to extract rare earth elements and subsequently produce large volumes of water leach purification (WLP) residue containing naturally occurring radioactive material (NORM). This residue has been rising up the environmental issue because it was suspected to accumulate thorium with significant activity concentration and has been classified as radioactive residue. The aim of this study is to determine Th-232, U-238 and rare earth elements in lanthanide concentrate (LC) and water leach purification (WLP) residue collected from LAMP and to evaluate the potential radiological impacts of the WLP residue on the environment. Instrumental Neutron Activation Analysis and γ-spectrometry were used for determination of Th, U and rare earth elements concentrations. The results of this study found that the concentration of Th in LC was 1289.7 ± 129 ppm (5274.9 ± 527.6Bq/kg) whereas the Th and U concentrations in WLP were determined to be 1952.9±17.6 ppm (7987.4 ± 71.9 Bq/kg) and 17.2 ± 2.4 ppm respectively. The concentrations of Th and U in LC and WLP samples determined by γ- spectrometry were 1156 ppm (4728 ± 22 Bq/kg) & 18.8 ppm and 1763.2 ppm (7211.4 Bq/kg) &29.97 ppm respectively. This study showed that thorium concentrations were higher in WLP compare to LC. This study also indicate that WLP residue has high radioactivity of 232Th compared to Malaysian soil natural background (63 - 110 Bq/kg) and come under preview of Act 304 and regulations. In LC, the Ce and Nd concentrations determined by INAA were 13.2 ± 0.6% and 4.7 ± 0.1% respectively whereas the concentrations of La, Ce, Nd and Sm in WLP were 0.36 ± 0.04%, 1.6%, 0.22% and 0.06% respectively. This result showed that some amount of rare earth had not been extracted and remained in the WLP and may be considered to be reextracted.

  9. Thorium, uranium and rare earth elements content in lanthanide concentrate (LC) and water leach purification (WLP) residue of Lynas advanced materials plant (LAMP)

    International Nuclear Information System (INIS)

    AL-Areqi, Wadeeah M.; Majid, Amran Ab.; Sarmani, Sukiman

    2014-01-01

    Lynas Advanced Materials Plant (LAMP) has been licensed to produce the rare earths elements since early 2013 in Malaysia. LAMP processes lanthanide concentrate (LC) to extract rare earth elements and subsequently produce large volumes of water leach purification (WLP) residue containing naturally occurring radioactive material (NORM). This residue has been rising up the environmental issue because it was suspected to accumulate thorium with significant activity concentration and has been classified as radioactive residue. The aim of this study is to determine Th-232, U-238 and rare earth elements in lanthanide concentrate (LC) and water leach purification (WLP) residue collected from LAMP and to evaluate the potential radiological impacts of the WLP residue on the environment. Instrumental Neutron Activation Analysis and γ-spectrometry were used for determination of Th, U and rare earth elements concentrations. The results of this study found that the concentration of Th in LC was 1289.7 ± 129 ppm (5274.9 ± 527.6Bq/kg) whereas the Th and U concentrations in WLP were determined to be 1952.9±17.6 ppm (7987.4 ± 71.9 Bq/kg) and 17.2 ± 2.4 ppm respectively. The concentrations of Th and U in LC and WLP samples determined by γ- spectrometry were 1156 ppm (4728 ± 22 Bq/kg) and 18.8 ppm and 1763.2 ppm (7211.4 Bq/kg) and 29.97 ppm respectively. This study showed that thorium concentrations were higher in WLP compare to LC. This study also indicate that WLP residue has high radioactivity of 232 Th compared to Malaysian soil natural background (63 - 110 Bq/kg) and come under preview of Act 304 and regulations. In LC, the Ce and Nd concentrations determined by INAA were 13.2 ± 0.6% and 4.7 ± 0.1% respectively whereas the concentrations of La, Ce, Nd and Sm in WLP were 0.36 ± 0.04%, 1.6%, 0.22% and 0.06% respectively. This result showed that some amount of rare earth had not been extracted and remained in the WLP and may be considered to be reextracted

  10. Thorium, Uranium and Rare Earth Elements content in lanthanide concentrate (LC) and water leach purification (WLP) residue of Lynas Advanced Materials Plant (LAMP)

    International Nuclear Information System (INIS)

    Al-Areqi, W.M.; Amran Abdul Majid; Sukiman Sarmani

    2013-01-01

    Full-text: Lynas Advanced Materials Plant (LAMP) has been licensed to produce the rare earths elements since early 2013 in Malaysia. LAMP processes lanthanide concentrate (LC) to extract rare earth elements and subsequently produce large volumes of water leach purification (WLP) residue containing naturally occurring radioactive material (NORM). This residue has been rising up the environmental issue because it was suspected to accumulate thorium with significant activity concentration and has been classified as radioactive residue. The aim of this study is to determine Th-232, U-238 and rare earth elements in lanthanide concentrate (LC) and water leach purification (WLP) residue collected from LAMP and to evaluate the potential radiological impacts of the WLP residue on the environment. Instrumental Neutron Activation Analysis and γ-spectrometry were used for determination of Th, U and rare earth elements concentrations. The results of this study found that the concentration of Th in LC was 1289.7 ± 129 ppm (5274.9 ± 527.6 Bq/ kg) whereas the Th and U concentrations in WLP were determined to be 1952.9 ± 17.6 ppm (7987.4 ± 71.9 Bq/ kg) and 17.2 ± 2.4 ppm respectively. The concentrations of Th and U in LC and WLP samples determined by γ- spectrometry were 1156 ppm (4728 ± 22 Bq/ kg) and 18.8 ppm and 1763.2 ppm (7211.4 Bq/ kg) and 29.97 ppm respectively. This study showed that thorium concentrations were higher in WLP compare to LC. This study also indicate that WLP residue has high radioactivity of 232 Th compared to Malaysian soil natural background (63 - 110 Bq/ kg) and come under preview of Act 304 and regulations. In LC, the Ce and Nd concentrations determined by INAA were 13.2 ± 0.6 % and 4.7 ± 0.1 % respectively whereas the concentrations of La, Ce, Nd and Sm in WLP were 0.36 ± 0.04 %, 1.6 %, 0.22 % and 0.06 % respectively. This result showed that some amount of rare earth had not been extracted and remained in the WLP and may be considered to be re

  11. Thorium, uranium and rare earth elements content in lanthanide concentrate (LC) and water leach purification (WLP) residue of Lynas advanced materials plant (LAMP)

    Energy Technology Data Exchange (ETDEWEB)

    AL-Areqi, Wadeeah M., E-mail: walareqi@yahoo.com; Majid, Amran Ab., E-mail: walareqi@yahoo.com; Sarmani, Sukiman, E-mail: walareqi@yahoo.com [Nuclear Science Programme, School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi (Malaysia)

    2014-02-12

    Lynas Advanced Materials Plant (LAMP) has been licensed to produce the rare earths elements since early 2013 in Malaysia. LAMP processes lanthanide concentrate (LC) to extract rare earth elements and subsequently produce large volumes of water leach purification (WLP) residue containing naturally occurring radioactive material (NORM). This residue has been rising up the environmental issue because it was suspected to accumulate thorium with significant activity concentration and has been classified as radioactive residue. The aim of this study is to determine Th-232, U-238 and rare earth elements in lanthanide concentrate (LC) and water leach purification (WLP) residue collected from LAMP and to evaluate the potential radiological impacts of the WLP residue on the environment. Instrumental Neutron Activation Analysis and γ-spectrometry were used for determination of Th, U and rare earth elements concentrations. The results of this study found that the concentration of Th in LC was 1289.7 ± 129 ppm (5274.9 ± 527.6Bq/kg) whereas the Th and U concentrations in WLP were determined to be 1952.9±17.6 ppm (7987.4 ± 71.9 Bq/kg) and 17.2 ± 2.4 ppm respectively. The concentrations of Th and U in LC and WLP samples determined by γ- spectrometry were 1156 ppm (4728 ± 22 Bq/kg) and 18.8 ppm and 1763.2 ppm (7211.4 Bq/kg) and 29.97 ppm respectively. This study showed that thorium concentrations were higher in WLP compare to LC. This study also indicate that WLP residue has high radioactivity of {sup 232}Th compared to Malaysian soil natural background (63 - 110 Bq/kg) and come under preview of Act 304 and regulations. In LC, the Ce and Nd concentrations determined by INAA were 13.2 ± 0.6% and 4.7 ± 0.1% respectively whereas the concentrations of La, Ce, Nd and Sm in WLP were 0.36 ± 0.04%, 1.6%, 0.22% and 0.06% respectively. This result showed that some amount of rare earth had not been extracted and remained in the WLP and may be considered to be reextracted.

  12. Experimental studies of methemoglobinemia due to percutaneous absorption of sodium nitrite.

    Science.gov (United States)

    Saito, T; Takeichi, S; Nakajima, Y; Yukawa, N; Osawa, M

    1997-01-01

    Methemoglobin formation caused by a liniment solution containing sodium nitrite (30 g/L and 140 g/L) was studied in rats with normal or abraded skin, by measuring the methemoglobin concentration before and after application of liniment solutions with differing nitrite concentration. Each liniment solution (120 microL) was applied. Methemoglobin was measured for 180 minutes using a hemoximeter. Simultaneously, arterial blood pressure and cutaneous blood flow was measured by laser Doppler flowmetry and a pressure transducer. After the application of each liniment solution to normal skin, the methemoglobin concentration was not significantly modified depending on the time after application. Application of liniment solution to abraded skin (140 g/L) resulted in a marked increase in methemoglobin concentration. A remarkable decrease in arterial blood pressure and subcutaneous blood flow were observed after application of liniment solution to abraded skin (140 g/L). Each of these findings are characteristic of nitrite and they imply the percutaneous absorption of nitrite. Regardless of the nitrite concentration, the methemoglobin concentration was consistently higher in abraded skin than in normal skin.

  13. Radiation preservation of low nitrite bacon

    International Nuclear Information System (INIS)

    Singh, H.

    1988-01-01

    Sodium nitrite, a key ingredient of the mix used to cure bacon and other meats, promotes and fixes bacon's characteristic pink color, inhibits lipid peroxidation and prevents growth of micro-organisms, particularly Clostridium botulinum spores. Unfortunately, nitrite leads to the formation of carcinogenic nitrosamines in bacon. This has led to a search for alternatives to the use of nitrite. Irradiation with reduced level of nitrite is a promising alternative. Radurization of bacon containing 20 to 40 mg/kg of nitrite in evacuated packages, irradiated and stored at 4 0 C, gives a product with good organoleptic qualities and extended shelf life of > 90 days, as opposed to ∼ 30 days for the conventionally treated bacon. Radappertization of bacon containing 20 mg/kg of nitrite at a dose of about 30 kGy, irradiated at temperature of -20 0 or lower in evacuated packages, results in a product that is shelf stable at room temperature for months to years. It has organoleptic qualities comparable to commercial bacon in terms of color, flavor, odor and texture. Irradiation also reduces the nitrite and preformed nitrosamines present in bacon. Various aspects of preservation of bacon are reviewed in this report with emphasis on radiation processing. (author)

  14. Rapid and simple preparation of rhodamine 6G loaded HY zeolite for highly selective nitrite detection

    Science.gov (United States)

    Viboonratanasri, Duangkamon; Pabchanda, Suwat; Prompinit, Panida

    2018-05-01

    In this study, a simple, rapid and relatively less toxic method for rhodamine 6G dye adsorption on hydrogen-form Y-type zeolite for highly selective nitrite detection was demonstrated. The adsorption behavior was described by Langmuir isotherm and the adsorption process reached the equilibrium promptly within a minute. The developed test papers characterized by fluorescence technique display high sensing performance with wide working range (0.04-20.0 mg L-1) and high selectivity. The test papers show good reproducibility with relative standard deviation (RSD) of 7% for five replicated determinations of 3 mg L-1 of nitrite. The nitrite concentration determined by using the test paper was in the same range as using ion chromatography within a 95% confidence level. The test papers offer advantages in terms of low cost and practical usage enabling them to be a promising candidate for nitrite sensor in environmental samples, food, and fertilizers.

  15. The kinetics for ammonium and nitrite oxidation under the effect of hydroxylamine.

    Science.gov (United States)

    Wan, Xinyu; Xiao, Pengying; Zhang, Daijun; Lu, Peili; Yao, Zongbao; He, Qiang

    2016-01-01

    The kinetics for ammonium (NH4(+)) oxidation and nitrite (NO2(-)) oxidation under the effect of hydroxylamine (NH2OH) were studied by respirometry using the nitrifying sludge from a laboratory-scale sequencing batch reactor. Modified models were used to estimate kinetics parameters of ammonia and nitrite oxidation under the effect of hydroxylamine. An inhibition effect of hydroxylamine on the ammonia oxidation was observed under different hydroxylamine concentration levels. The self-inhibition coefficient of hydroxylamine oxidation and noncompetitive inhibition coefficient of hydroxylamine for nitrite oxidation was estimated by simulating exogenous oxygen-uptake rate profiles, respectively. The inhibitive effect of NH2OH on nitrite-oxidizing bacteria was stronger than on ammonia-oxidizing bacteria. This work could provide fundamental data for the kinetic investigation of the nitrification process.

  16. Bioelectrode-based approach for enhancing nitrate and nitrite removal and electricity generation from eutrophic lakes

    DEFF Research Database (Denmark)

    Zhang, Yifeng; Angelidaki, Irini

    Nitrate and nitrite contamination of surface waters (e.g. lakes) has become a severe environmental and health problem, especially in developing countries. The recent demonstration of nitrate reduction at the cathode of microbial fuel cell (MFC) provides an opportunity to develop a new technology...... from nitrate- and nitrite-rich synthetic lake waters at initial concentration of 10 mg-N/L. Along with the electricity production a total nitrogen removal of 62% and 77% was accomplished, for nitrate and nitrite, respectively. The nitrogen removal was almost 4 times higher under close-circuit condition...... with biocathode, compared to either the open-circuit operation or with abiotic cathode. The mass balance on nitrogen indicates that most of the removed nitrate and nitrite (84.7±0.1% and 81.8±0.1%, respectively) was reduced to nitrogen gas. The nitrogen removal and power generation was limited by the dissolved...

  17. Changes of sodium nitrate, nitrite, and N-nitrosodiethylamine during in vitro human digestion.

    Science.gov (United States)

    Kim, Hyeong Sang; Hur, Sun Jin

    2017-06-15

    This study aimed to determine the changes in sodium nitrate, sodium nitrite, and N-nitrosodiethylamine (NDEA) during in vitro human digestion, and the effect of enterobacteria on the changes in these compounds. The concentrations of nitrate, nitrite, and NDEA were significantly reduced from 150, 150, and 1ppm to 42.8, 63.2, and 0.85ppm, respectively, during in vitro human digestion (pdigestion. This study is the first to report that E. coli can dramatically reduce the amount of nitrite during in vitro human digestion and this may be due to the effect of nitrite reductase present in E. coli. We therefore conclude that the amounts of potentially harmful substances and their toxicity can be decreased during human digestion. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Determination of nitrite ion at schiff's base derivative of chitosan modified glassy carbon electrode

    International Nuclear Information System (INIS)

    Xu Zhongliang; Zhang Jianmei; Liu Shujuan; Peng Daofeng

    2007-01-01

    Chitosan react with salicyclaldehyde by schiff's base reaction in water, a polymer product S-CTS can be prepared. Glassy carbon electrode was modified with S-CTS by drop-coating method. Then, its electrocatalysis effect on the reduction of nitrite by the films of S-CTS was investigated. Experimental results showed that S-CTS modified electrode could reduce the oxidation overpotential of nitrite in pH4.5 B-R buffer solution, the peak current of reduction was proportional to the concentration of nitrite and a good linear relation from 0.20 to 81 mg/kg (r=0.9899) with a detection limit of 2.8 x 10 -7 mol/L was obtained. The methods have been applied to determining nitrite in some samples, satisfactory results were obtained. (authors)

  19. The acclimation of Chlorella to high-level nitrite for potential application in biological NOx removal from industrial flue gases.

    Science.gov (United States)

    Li, Tianpei; Xu, Gang; Rong, Junfeng; Chen, Hui; He, Chenliu; Giordano, Mario; Wang, Qiang

    2016-05-20

    Nitrogen oxides (NOx) are the components of fossil flue gas that give rise to the greatest environmental concerns. This study evaluated the ability of the green algae Chlorella to acclimate to high level of NOx and the potential utilization of Chlorella strains in biological NOx removal (DeNOx) from industrial flue gases. Fifteen Chlorella strains were subject to high-level of nitrite (HN, 176.5 mmolL(-1) nitrite) to simulate exposure to high NOx. These strains were subsequently divided into four groups with respect to their ability to tolerate nitrite (excellent, good, fair, and poor). One strain from each group was selected to evaluate their photosynthetic response to HN condition, and the nitrite adaptability of the four Chlorella strains were further identified by using chlorophyll fluorescence. The outcome of our experiments shows that, although high concentrations of nitrite overall negatively affect growth and photosynthesis of Chlorella strains, the degree of nitrite tolerance is a strain-specific feature. Some Chlorella strains have an appreciably higher ability to acclimate to high-level of nitrite. Acclimation is achieved through a three-step process of restrict, acclimate, and thriving. Notably, Chlorella sp. C2 was found to have a high tolerance and to rapidly acclimate to high concentrations of nitrite; it is therefore a promising candidate for microalgae-based biological NOx removal. Copyright © 2016 Elsevier GmbH. All rights reserved.

  20. Periodontal Therapy Effects on Nitrite Related to Oral Bacteria: A 6-Month Randomized Clinical Trial.

    Science.gov (United States)

    Cortelli, Sheila C; Costa, Fernando O; Rodrigues, Edson; Cota, Luis O M; Cortelli, Jose R

    2015-08-01

    Nitrite is a biologic factor relevant to oral and systemic homeostasis. Through an oral bacteria reduction process, it was suggested that periodontal therapy and chlorhexidine (CHX) rinse could affect nitrite levels, leading to negative effects, such as an increase in blood pressure. This 6-month randomized clinical trial evaluated the effects of periodontal therapeutic protocols on salivary nitrite and its relation to subgingival bacteria. One hundred patients with periodontitis were allocated randomly to debridement procedures in four weekly sections (quadrant scaling [QS]) or within 24 hours (full-mouth scaling [FMS]) in conjunction with a 60-day CHX (QS + CHX and FMS + CHX), placebo (QS + placebo and FMS + placebo), or no mouthrinse (QS + none and FMS + none) use. Real-time polymerase chain reaction determined total bacterial, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Streptococcus oralis, and Actinomyces naeslundii levels. Salivary nitrite concentration was determined with Griess reagent. Data were analyzed statistically at baseline and 3 and 6 months by analysis of variance, Kruskal-Wallis, Mann-Whitney U, and Spearman correlation tests (P periodontal pockets. The relationship between nitrite and bacterial levels appears weak. Short-term scaling exhibited a greater influence on nitrite concentrations then long-term CHX use.

  1. Nitrites and nitrates in exhaled breath condensate in cystic fibrosis: relation to clinical parameters.

    Science.gov (United States)

    Fila, L; Chladek, J; Maly, M; Musil, J

    2013-01-01

    To evaluate correlation of exhaled breath condensate (EBC) nitrite and nitrate concentrations with disease severity in cystic fibrosis (CF) patients. Nitrites and nitrates are products of oxidative metabolism of nitric oxide. Impaired metabolism of nitric oxide plays a role in pathogenesis of CF. EBC was collected from 46 stable CF patients and from 21 healthy controls. EBC concentrations of nitrites and nitrates were correlated with parameters of lung disease and nutritional status and with systemic inflammatory markers. EBC nitrates concentrations in CF patients were lower than in healthy subjects (5.8 vs 14.3 μmol/l, pnitrates concentrations correlate with disease severity in CF patients and are lower than in healthy subjects (Tab. 4, Fig. 1, Ref. 48).

  2. Nitrite disrupts multiple physiological functions in aquatic animals

    DEFF Research Database (Denmark)

    Jensen, Frank Bo

    2003-01-01

    be inhibited, while changes in ammonia and urea levels and excretion rates reflect an influence of nitrite on nitrogen metabolism. Detoxification of nitrite occurs via endogenous oxidation to nitrate, and elimination of nitrite takes place both via gills and urine. The susceptibility to nitrite varies between...... nitrite-induced vasodilation (possibly via nitric oxide generated from nitrite) that is countered by increased cardiac pumping to re-establish blood pressure. Nitrite can form and/or mimic nitric oxide and thereby interfere with processes regulated by this local hormone. Steroid hormone synthesis may...

  3. Dietary nitrates, nitrites, and cardiovascular disease.

    Science.gov (United States)

    Hord, Norman G

    2011-12-01

    Dietary nitrate (NO(3)), nitrite (NO(2)), and arginine can serve as sources for production of NO(x) (a diverse group of metabolites including nitric oxide, nitrosothiols, and nitroalkenes) via ultraviolet light exposure to skin, mammalian nitrate/nitrite reductases in tissues, and nitric oxide synthase enzymes, respectively. NO(x) are responsible for the hypotensive, antiplatelet, and cytoprotective effects of dietary nitrates and nitrites. Current regulatory limits on nitrate intakes, based on concerns regarding potential risk of carcinogenicity and methemoglobinemia, are exceeded by normal daily intakes of single foods, such as soya milk and spinach, as well as by some recommended dietary patterns such as the Dietary Approaches to Stop Hypertension diet. This review includes a call for regulatory bodies to consider all available data on the beneficial physiologic roles of nitrate and nitrite in order to derive rational bases for dietary recommendations.

  4. Diversity of nitrite reductase genes (nirS) in the denitrifying water column of the coastal Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Jayakumar, D.A.; Francis, C.A.; Naqvi, S.W.A.; Ward, B.B.

    Denitrification often occurs in the water column, underlying zones of intense productivity and decomposition in upwelling regions. In the denitrifying zone off the southwest coast of India, high concentrations of nitrite (greater than 15 mu M...

  5. Spectrophotometric determination of nitrite in simulated Purex Process solutions

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, I.daC. de; Matsuda, H T; Araujo, B.F. de; Araujo, J.A. de

    1984-01-01

    A spectrophotometric method for nitrite determination in simulated Purex Process solutions is presented, utilizing the Griess reagent for the formation of the coloured azocompound with an absorption maximum at 525 nm. Molar absortivity was 36,262 and the sensitivity of the method 10/sup -6/M for nitrite. The calibration curve is linear in the range of 2 to 30..mu..g NO/sup -//sub 2//25 ml in cells of 1 cm optical path. The method can be used in the presence of uranium up to limits of an U/NO/sup -//sub 2/ ratio of 150. Test solutions were prepared to simulate composition and concentrations as obtained by irradiating standard fuel with a neutro flux of 3.2 x 10/sup 13/ n.s/sup -1/.cm/sup -2/, with a burn-up value of 33,000 Mwd/T and cooling time of two years. Nitrite determinations in these solutions were accurate within limits of 5%.

  6. Association of nitrate, nitrite, and total organic carbon (TOC) in drinking water and gastrointestinal disease.

    Science.gov (United States)

    Khademikia, Samaneh; Rafiee, Zahra; Amin, Mohammad Mehdi; Poursafa, Parinaz; Mansourian, Marjan; Modaberi, Amir

    2013-01-01

    We aimed to investigate the amounts of nitrate, nitrite, and total organic carbon (TOC) in two drinking water sources and their relationship with some gastrointestinal diseases. This cross-sectional study was conducted in 2012 in Iran. Two wells located in residential areas were selected for sampling and measuring the TOC, nitrate (NO3(-)), and nitrite (NO2(-)). This water is used for drinking as well as for industrial and agricultural consumption. Nitrate and nitrite concentrations of water samples were analyzed using DR 5000 spectrophotometer. The information of patients was collected from the records of the main referral hospital of the region for gastrointestinal diseases. In both areas under study, the mean water nitrate and nitrite concentrations were higher in July than in other months. The mean TOC concentrations in areas 1 and 2 were 2.29 ± 0.012 and 2.03 ± 0.309, respectively. Pollutant concentration and gastrointestinal disease did not show any significant relationship (P > 0.05). Although we did not document significant association of nitrite, nitrate, and TOC content of water with gastrointestinal diseases, it should be considered that such health hazards may develop over time, and the quality of water content should be controlled to prevent different diseases.

  7. Electro-oxidation nitrite based on copper calcined layered double hydroxide and gold nanoparticles modified glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Cui Lin; Meng Xiaomeng; Xu Minrong; Shang Kun [College of Chemistry and Material Science, Shandong Agricultural University, Taian 271018, Shandong (China); Ai Shiyun, E-mail: ashy@sdau.edu.cn [College of Chemistry and Material Science, Shandong Agricultural University, Taian 271018, Shandong (China); Liu Yinping [College of Chemistry and Material Science, Shandong Agricultural University, Taian 271018, Shandong (China)

    2011-11-30

    Highlights: > A nitrite sensor fabricated based on copper calcined layered double hydroxides and gold nanoparticles modified electrode. > This sensor exhibited excellent electrocatalytic oxidation to nitrite. > This nitrite sensor exhibited very good analytical performance with low cost, convenient preparation and rapid detection. - Abstract: In this paper, a novel nitrite sensor was constructed based on electrodeposition of gold nanoparticles (AuNPs) on a copper calcined layered double hydroxide (Cu-CLDH) modified glassy carbon electrode. Electrochemical experiments showed that AuNPs/CLDH composite film exhibited excellent electrocatalytic oxidation activity with nitrite due to the synergistic effect of the Cu-CLDH with AuNPs. The fabricated sensor exhibited excellent performance for nitrite detection within a wide concentration interval of 1-191 {mu}M and with a detection limit of 0.5 {mu}M. The superior electrocatalytic response to nitrite was mainly attributed to the large surface area, minimized diffusion resistance, and enhanced electron transfer of the Cu-CLDH and AuNPs composition film. This platform offers a novel route for nitrite sensing with wide analytical applications and will supply the practical applications for a variety of simple, robust, and easy-to-manufacture analytical approaches in the future.

  8. Electro-oxidation nitrite based on copper calcined layered double hydroxide and gold nanoparticles modified glassy carbon electrode

    International Nuclear Information System (INIS)

    Cui Lin; Meng Xiaomeng; Xu Minrong; Shang Kun; Ai Shiyun; Liu Yinping

    2011-01-01

    Highlights: → A nitrite sensor fabricated based on copper calcined layered double hydroxides and gold nanoparticles modified electrode. → This sensor exhibited excellent electrocatalytic oxidation to nitrite. → This nitrite sensor exhibited very good analytical performance with low cost, convenient preparation and rapid detection. - Abstract: In this paper, a novel nitrite sensor was constructed based on electrodeposition of gold nanoparticles (AuNPs) on a copper calcined layered double hydroxide (Cu-CLDH) modified glassy carbon electrode. Electrochemical experiments showed that AuNPs/CLDH composite film exhibited excellent electrocatalytic oxidation activity with nitrite due to the synergistic effect of the Cu-CLDH with AuNPs. The fabricated sensor exhibited excellent performance for nitrite detection within a wide concentration interval of 1-191 μM and with a detection limit of 0.5 μM. The superior electrocatalytic response to nitrite was mainly attributed to the large surface area, minimized diffusion resistance, and enhanced electron transfer of the Cu-CLDH and AuNPs composition film. This platform offers a novel route for nitrite sensing with wide analytical applications and will supply the practical applications for a variety of simple, robust, and easy-to-manufacture analytical approaches in the future.

  9. Determination of five abused drugs in nitrite-adulterated urine by immunoassays and gas chromatography-mass spectrometry.

    Science.gov (United States)

    Tsai, S C; ElSohly, M A; Dubrovsky, T; Twarowska, B; Towt, J; Salamone, S J

    1998-10-01

    The adulteration of urine specimens with nitrite ion hasseen shown to mask the gas chromatography-mass spectrometry (GC-MS) confirmation testing of marijuana use. This study was designed to further investigate the effect of nitrite adulteration on the detection of five commonly abused drugs by immunoassay screening and GC-MS analysis. The drugs tested are cocaine metabolite (benzoylecgonine), morphine, 11-nor-delta-tetrahydrocannabinol-9-carboxylic acid (THCCOOH), amphetamine, and phencyclidine. The immunoassays evaluated included the instrument-based Abuscreen ONLINE assays, the on-site Abuscreen ONTRAK assays, and the one-step ONTRAK TESTCUP-5 assay. Multianalyte standards containing various levels of drugs were used to test the influence of both potassium and sodium nitrite. In the ONLINE immunoassays, the presence of up to 1.0M nitrite in the multianalyte standards had no significant effect for benzoylecgonine, morphine, and phencyclidine assays. With a high concentration of nitrite, ONLINE became more sensitive for amphetamine (detected more drug than what was expected) and less sensitive for THCCOOH (detected less drug than what was expected). No effects of nitrite were observed on the results of the Abuscreen ONTRAK assays. Similarly, no effects were observed on the absolute qualitative results of the TESTCUP-5 when testing the nitrite-adulterated standards. However, the produced intensities of the signals that indicate the negative test results were slightly lowered in the THC and phencyclidine assays. The presence of 1.0M of nitrite did not show dramatic interference with the GC-MS analysis of benzoylecgonine, morphine, amphetamine, and phencyclidine. In contrast, nitrite ion significantly interfered with the detection of THCCOOH by GC-MS. The presence of 0.03M of nitrite ion resulted in significant loss in the recovery of THCCOOH and its internal standard by GC-MS. The problem of nitrite adulteration could be alleviated by sodium bisulfite treatment even

  10. Sorbate-nitrite interactions: acetonitrile oxide as an alkylating agent.

    Science.gov (United States)

    Pérez-Prior, M Teresa; Gómez-Bombarelli, Rafael; González-Pérez, Marina; Manso, José A; García-Santos, M Pilar; Calle, Emilio; Casado, Julio

    2009-07-01

    Because chemical species with DNA-damaging and mutagenic activity are formed in sorbate-nitrite mixtures and because sorbic acid sometimes coexists with nitrite occurring naturally or incorporated as a food additive, the study of sorbate-nitrite interactions is important. Here, the alkylating potential of the products resulting from such interactions was investigated. Drawn were the following conclusions: (i) Acetonitrile oxide (ACNO) is the compound responsible for the alkylating capacity of sorbate-nitrite mixtures; (ii) ACNO alkylates 4-(p-nitrobenzyl)pyridine (NBP), a trap for alkylating agents with nucleophilic characteristics similar to those of DNA bases, forming an adduct (AD; epsilon = 1.4 x 10(4) M(-1) cm(-1); lambda = 519 nm); (iii) the NBP alkylation reaction complies with the rate equation, r = d[AD]/dt = k(alk)(ACNO)[ACNO][NBP]-k(hyd)(AD)[AD], k(alk)(ACNO) being the NBP alkylation rate constant for ACNO and k(hyd)(AD) the rate constant for the adduct hydrolysis reaction; (iv) the small fraction of ACNO forming the adduct with NBP, as well as the small magnitude of the quotient (k(alk) (ACNO)/k(hyd)(ACNO)) as compared with those reported for other alkylating agents, such as some lactones and N-alkyl-N-nitrosoureas, reveals the ACNO effective alkylating capacity to be less significant; (v) the low value of the NBP-ACNO adduct life (defined as the total amount of adduct present along the progression of the NBP alkylation per unit of alkylating agent concentration) points to the high instability of this adduct; and (vi) the obtained results are in accordance with the low carcinogenicity of ACNO.

  11. Experimental Study of Leaching and Penetration of Nitrite ions in Nitrite-type Repair Materials on the Surface of Concrete

    Directory of Open Access Journals (Sweden)

    Masumi Inoue

    2017-01-01

    Full Text Available This study aimed to clarify the leaching properties of nitrite ions in nitrite-type repair materials exposed to rainfall. Repaired concrete specimens were prepared for leaching tests using a lithium nitrite solution, and the amounts of leaching and penetration of nitrite ions were measured under simulated rainfall. The results demonstrated that the amount of leaching could be controlled by using polymer cement paste and mortar surface coatings containing lithium nitrite solution, and by using polymer cement mortar surface coatings following direct lithium nitrite solution coatings. Furthermore, the amount of nitrite ion leaching in all cases was lower than the discharge standard value established by the water pollution control law.

  12. Combined effects of gamma radiation doses and sodium nitrite content on the lipid oxidation and color of mortadella.

    Science.gov (United States)

    Dutra, Monalisa Pereira; Cardoso, Giselle Pereira; Fontes, Paulo Rogério; Silva, Douglas Roberto Guimarães; Pereira, Marcio Tadeu; Ramos, Alcinéia de Lemos Souza; Ramos, Eduardo Mendes

    2017-12-15

    The effects of different doses of gamma radiation (0-20kGy) on the color and lipid oxidation of mortadella prepared with increasing nitrite levels (0-300ppm) were evaluated using a central composite rotatable design. Higher radiation doses increased the redox potential, promoted the lipid oxidation and elevating the hue color of the mortadellas. Nevertheless, higher addition of sodium nitrite elevated the residual nitrite content, reduced the lipid oxidation and promoted the increase of redness and the reduce of hue color of the mortadellas, regardless of the radiation dose applied. Nitrite addition had a greater effect than irradiation on the quality parameters evaluated, and even at low levels (∼75ppm), its use decreased the deleterious effects of irradiation at doses as high as 20kGy. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Electrocatalytic reduction of nitrite using ferricyanide; Application for its simple and selective determination

    International Nuclear Information System (INIS)

    Ojani, Reza; Raoof, Jahan-Bakhsh; Zarei, Ebrahim

    2006-01-01

    The electrocatalytic reduction of nitrite has been studied by ferricyanide at the surface of carbon paste electrode. Cyclic voltammetry and chronoamperometry techniques were used to investigate the suitability of ferricyanide as a mediator for the electrocatalytic nitrite reduction in aqueous solution with various pH. Results showed that pH 0.00 is the most suitable for this purpose. In the optimum pH, the electrocatalytic ability about 700 mV can be seen and the homogeneous second-order rate constant (k s ) for nitrite coupled catalytically to ferricyanide was calculated 2.75 x 10 3 M -1 s -1 by Nicholson-Shain method. Also, electron transfer coefficients (α) for ferricyanide was determined by using various electrochemical approaches such as Tafel plot in the absence and presence of nitrite 0.556 and 0.760, respectively. The catalytic reduction peak current was linearly dependent on the nitrite concentration and the linearity range obtained was 5.00 x 10 -5 to 1.00 x 10 -3 M. Detection limit has been found to be 2.63 x 10 -5 M (2σ). This method has been applied as a selective, simple and precise method for determination of nitrite in real sample

  14. Nisin: a possible alternative or adjunct to nitrite in the preservation of meats.

    Science.gov (United States)

    Rayman, M K; Aris, B; Hurst, A

    1981-01-01

    Nisin at 75 ppm (75 microgram/g) was superior to 150 ppm of nitrite in inhibiting outgrowth of Clostridium sporogenes PA3679 spores in meat slurries, which had been heated to simulate the process used for cooked ham. The inhibitory activity of nisin decreased as the spore load or pH of the slurries increased. Unlike nitrite, inhibition by nisin was unaffected by high levels of iron either as a constituent of meats or when added as an iron salt. In slurries treated with 75 ppm of nisin, refrigerated storage for 56 days resulted in depletion of nisin to a level low enough to allow outgrowth within 3 to 10 days if the slurries were subsequently abused at 35 degrees C. In contrast, a combination of 40 ppm of nitrite and either 75 or 100 ppm of nisin almost completely inhibited outgrowth in these slurries. The nisin-nitrite combination appeared to have a synergistic effect, and the low concentration of nitrite was sufficient to preserve the color in meats similar to that of products cured with 150 ppm of nitrite. PMID:7195188

  15. NITRITE REDUCTASE ACTIVITY OF NON-SYMBIOTIC HEMOGLOBINS FROM ARABIDOPSIS THALIANA†

    Science.gov (United States)

    Tiso, Mauro; Tejero, Jesús; Kenney, Claire; Frizzell, Sheila; Gladwin, Mark T.

    2013-01-01

    Plant non-symbiotic hemoglobins possess hexa-coordinate heme geometry similar to the heme protein neuroglobin. We recently discovered that deoxygenated neuroglobin converts nitrite to nitric oxide (NO), an important signaling molecule involved in many processes in plants. We sought to determine whether Arabidopsis thaliana non-symbiotic hemoglobins class 1 and 2 (AHb1 and AHb2) might function as nitrite reductases. We found that the reaction of nitrite with deoxygenated AHb1 and AHb2 generates NO gas and iron-nitrosyl-hemoglobin species. The bimolecular rate constants for nitrite reduction to NO are 19.8 ± 3.2 and 4.9 ± 0.2 M−1s−1, at pH = 7.4 and 25°C, respectively. We determined the pH dependence of these bimolecular rate constants and found a linear correlation with the concentration of protons, indicating the requirement for one proton in the reaction. Release of free NO gas during reaction in anoxic and hypoxic (2% oxygen) conditions was confirmed by chemiluminescence detection. These results demonstrate that deoxygenated AHb1 and AHb2 reduce nitrite to form NO via a mechanism analogous to that observed for hemoglobin, myoglobin and neuroglobin. Our findings suggest that during severe hypoxia and in the anaerobic plant roots, especially in water submerged species, non-symbiotic hemoglobins provide a viable pathway for NO generation via nitrite reduction. PMID:22620259

  16. Haematological and ion regulatory effects of nitrite in the air-breathing snakehead fish Channa striata

    DEFF Research Database (Denmark)

    Lefevre, Sjannie; Jensen, Frank B.; Huong, Do T.T.

    2012-01-01

    M. Effects of sub-lethal exposures to nitrite (0 mM, 1.4 mM, and 3.0 mM) were determined during a 7-day exposure period. Plasma nitrite increased, but the internal concentration remained well below ambient levels. Extracellular nitrate rose by several mM, indicating that a large proportion of the nitrite...... taken up was converted to nitrate. Nitrite reacted with erythrocyte haemoglobin (Hb) causing methaemoglobin (metHb) to increase to 30% and nitrosylhaemoglobin (HbNO) to increase to 10% of total Hb. Both metHb and HbNO stabilised after 4 days, and functional Hb levels accordingly never fell below 60......The tolerance and effects of nitrite on ion balance and haematology were investigated in the striped snakehead, Channa striata Bloch 1793, which is an air-breathing fish with reduced gills of importance for aquaculture in South East Asia. C. striata was nitrite tolerant with a 96 h LC50 of 4.7 m...

  17. Nitrite oxidation kinetics of two Nitrospira strains: The quest for competition and ecological niche differentiation.

    Science.gov (United States)

    Ushiki, Norisuke; Jinno, Masaru; Fujitani, Hirotsugu; Suenaga, Toshikazu; Terada, Akihiko; Tsuneda, Satoshi

    2017-05-01

    Nitrite oxidation is an aerobic process of the nitrogen cycle in natural ecosystems, and is performed by nitrite-oxidizing bacteria (NOB). Also, nitrite oxidation is a rate-limiting step of nitrogen removal in wastewater treatment plants (WWTPs). Although Nitrospira is known as dominant NOB in WWTPs, information on their physiological properties and kinetic parameters is limited. Here, we report the kinetic parameters and inhibition of nitrite oxidation by free ammonia in pure cultures of Nitrospira sp. strain ND1 and Nitrospira japonica strain NJ1, which were previously isolated from activated sludge in a WWTP. The maximum nitrite uptake rate ( [Formula: see text] ) and the half-saturation constant for nitrite uptake ( [Formula: see text] ) of strains ND1 and NJ1 were 45 ± 7 and 31 ± 5 (μmol NO 2 - /mg protein/h), and 6 ± 1 and 10 ± 2 (μM NO 2 - ), respectively. The [Formula: see text] and [Formula: see text] of two strains indicated that they adapt to low-nitrite-concentration environments like activated sludge. The half-saturation constants for oxygen uptake ( [Formula: see text] ) of the two strains were 4.0±2.5 and 2.6±1.1 (μM O 2 ), respectively. The [Formula: see text] values of the two strains were lower than those of other NOB, suggesting that Nitrospira in activated sludge could oxidize nitrite in the hypoxic environments often found in the interiors of biofilms and flocs. The inhibition thresholds of the two strains by free ammonia were 0.85 and 4.3 (mg-NH 3 l -1 ), respectively. Comparing the physiological properties of the two strains, we suggest that tolerance for free ammonia determines competition and partitioning into ecological niches among Nitrospira populations. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  18. Increased hydrazine during partial nitritation process in upflow air-lift reactor fed with supernatant of anaerobic digester effluent

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jeongdong [University of Alberta, Alberta (Canada); Jung, Sokhee [Samsung SDS, Seoul (Korea, Republic of); Ahn, Young-Ho [Yeungnam University, Gyungsan (Korea, Republic of)

    2013-06-15

    The optimal balance of ammonium and nitrite is essential for successful operation of the subsequent anammox process. We conducted a partial nitritation experiment using an upflow air-lift reactor to provide operational parameters for achieving the optimal ratio of ammonium to nitrite, by feeding supernatant of anaerobic digester effluent, high-nitrogen containing rejection water. Semi-continuous operation results show that HRT should be set between 15 and 17 hours to achieve the optimum ration of 1.3 of NO{sub 2}-N/NH{sub 4}-N. In the UAR, nitritation was the dominant reaction due to high concentration of ammonia and low biodegradable organics. The influent contained low concentrations of hydroxylamine and hydrazine. However, hydrazine increased during partial nitritation by ⁓60-130% although there was no potential anammox activity in the reactor. The partial nitritation process successfully provided the ratio of nitrogen species for the anammox reaction, and relived the nitrite restraint on the anammox activity by increasing hydrazine concentration.

  19. Safety and feasibility of long-term intravenous sodium nitrite infusion in healthy volunteers.

    Directory of Open Access Journals (Sweden)

    Ryszard M Pluta

    Full Text Available BACKGROUND: Infusion of sodium nitrite could provide sustained therapeutic concentrations of nitric oxide (NO for the treatment of a variety of vascular disorders. The study was developed to determine the safety and feasibility of prolonged sodium nitrite infusion. METHODOLOGY: Healthy volunteers, aged 21 to 60 years old, were candidates for the study performed at the National Institutes of Health (NIH; protocol 05-N-0075 between July 2007 and August 2008. All subjects provided written consent to participate. Twelve subjects (5 males, 7 females; mean age, 38.8±9.2 years (range, 21-56 years were intravenously infused with increasing doses of sodium nitrite for 48 hours (starting dose at 4.2 µg/kg/hr; maximal dose of 533.8 µg/kg/hr. Clinical, physiologic and laboratory data before, during and after infusion were analyzed. FINDINGS: The maximal tolerated dose for intravenous infusion of sodium nitrite was 267 µg/kg/hr. Dose limiting toxicity occurred at 446 µg/kg/hr. Toxicity included a transient asymptomatic decrease of mean arterial blood pressure (more than 15 mmHg and/or an asymptomatic increase of methemoglobin level above 5%. Nitrite, nitrate, S-nitrosothiols concentrations in plasma and whole blood increased in all subjects and returned to preinfusion baseline values within 12 hours after cessation of the infusion. The mean half-life of nitrite estimated at maximal tolerated dose was 45.3 minutes for plasma and 51.4 minutes for whole blood. CONCLUSION: Sodium nitrite can be safely infused intravenously at defined concentrations for prolonged intervals. These results should be valuable for developing studies to investigate new NO treatment paradigms for a variety of clinical disorders, including cerebral vasospasm after subarachnoid hemorrhage, and ischemia of the heart, liver, kidney and brain, as well as organ transplants, blood-brain barrier modulation and pulmonary hypertension. CLINICAL TRIAL REGISTRATION INFORMATION: http

  20. A carbon nanotube/polyvanillin composite film as an electrocatalyst for the electrochemical oxidation of nitrite and its application as a nitrite sensor

    Energy Technology Data Exchange (ETDEWEB)

    Zheng Dongyun [College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072 (China); State Key Laboratory of Transducer Technology, Chinese Academy of Sciences (China); Hu Chengguo [College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072 (China); State Key Laboratory of Transducer Technology, Chinese Academy of Sciences (China)], E-mail: cghu@whu.edu.cn; Peng Yanfen [College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072 (China); State Key Laboratory of Transducer Technology, Chinese Academy of Sciences (China); Hu Shengshui [College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072 (China); State Key Laboratory of Transducer Technology, Chinese Academy of Sciences (China)], E-mail: sshu@whu.edu.cn

    2009-08-30

    We report a simple method for the stable dispersion of multi-walled carbon nanotubes (MWNTs) in water by vanillin and controllable surface addition onto carbon fiber microelectrodes (CFE) via electropolymerization. We have characterized these polyvanillin-carbon nanotube (PVN-MWNT) composite films with techniques including scanning electron microscopy (SEM), infrared spectroscopy (IR) and voltammetry. These investigations showed that the films have a uniform porous nanostructure with a large surface area. This PVN-MWNT composite-modified CFE (PVN-MWNT/CFE) exhibited a sensitive response to the electrochemical oxidation of nitrite. Under optimal working conditions, the oxidation peak current of nitrite linearly increased with its concentration in the range of 0.2 {mu}M-3.1 mM, with the system exhibiting a lower detection limit of 50 nM (S/N = 3). We successfully applied the PVN-MWNT/CFE system to the determination of nitrite from lake water. The efficient recovery of nitrite indicated that this electrode was able to detect nitrite in real samples.

  1. Shewanella oneidensis cytochrome c nitrite reductase (ccNiR) does not disproportionate hydroxylamine to ammonia and nitrite, despite a strongly favorable driving force.

    Science.gov (United States)

    Youngblut, Matthew; Pauly, Daniel J; Stein, Natalia; Walters, Daniel; Conrad, John A; Moran, Graham R; Bennett, Brian; Pacheco, A Andrew

    2014-04-08

    Cytochrome c nitrite reductase (ccNiR) from Shewanella oneidensis, which catalyzes the six-electron reduction of nitrite to ammonia in vivo, was shown to oxidize hydroxylamine in the presence of large quantities of this substrate, yielding nitrite as the sole free nitrogenous product. UV-visible stopped-flow and rapid-freeze-quench electron paramagnetic resonance data, along with product analysis, showed that the equilibrium between hydroxylamine and nitrite is fairly rapidly established in the presence of high initial concentrations of hydroxylamine, despite said equilibrium lying far to the left. By contrast, reduction of hydroxylamine to ammonia did not occur, even though disproportionation of hydroxylamine to yield both nitrite and ammonia is strongly thermodynamically favored. This suggests a kinetic barrier to the ccNiR-catalyzed reduction of hydroxylamine to ammonia. A mechanism for hydroxylamine reduction is proposed in which the hydroxide group is first protonated and released as water, leaving what is formally an NH2(+) moiety bound at the heme active site. This species could be a metastable intermediate or a transition state but in either case would exist only if it were stabilized by the donation of electrons from the ccNiR heme pool into the empty nitrogen p orbital. In this scenario, ccNiR does not catalyze disproportionation because the electron-donating hydroxylamine does not poise the enzyme at a sufficiently low potential to stabilize the putative dehydrated hydroxylamine; presumably, a stronger reductant is required for this.

  2. Effects of nitrite exposure on functional haemoglobin levels, bimodal respiration, and swimming performance in the facultative air-breathing fish Pangasianodon hypophthalmus

    Energy Technology Data Exchange (ETDEWEB)

    Lefevre, Sjannie, E-mail: sjannie.lefevre@biology.au.dk [Zoophysiology, Department of Biological Sciences, Aarhus University, Aarhus (Denmark); Jensen, Frank B. [Department of Biology, University of Southern Denmark, Odense (Denmark); Huong, Do.T.T. [College of Aquaculture and Fisheries, Can Tho University, Can Tho City (Viet Nam); Wang, Tobias [Zoophysiology, Department of Biological Sciences, Aarhus University, Aarhus (Denmark); Phuong, Nguyen T. [College of Aquaculture and Fisheries, Can Tho University, Can Tho City (Viet Nam); Bayley, Mark [Zoophysiology, Department of Biological Sciences, Aarhus University, Aarhus (Denmark)

    2011-07-15

    In this study we investigated nitrite (NO{sub 2}{sup -}) effects in striped catfish, a facultative air-breather. Fish were exposed to 0, 0.4, and 0.9 mM nitrite for 0, 1, 2, 4, and 7 days, and levels of functional haemoglobin, methaemoglobin (metHb) and nitrosyl haemoglobin (HbNO) were assessed using spectral deconvolution. Plasma concentrations of nitrite, nitrate, chloride, potassium, and sodium were also measured. Partitioning of oxygen consumption was determined to reveal whether elevated metHb (causing functional hypoxia) induced air-breathing. The effects of nitrite on maximum oxygen uptake (MO{sub 2max}) and critical swimming speed (U{sub crit}) were also assessed. Striped catfish was highly tolerant to nitrite exposure, as reflected by a 96 h LC{sub 50} of 1.65 mM and a moderate nitrite uptake into the blood. Plasma levels of nitrite reached a maximum after 1 day of exposure, and then decreased, never exceeding ambient levels. MetHb, HbNO and nitrate (a nitrite detoxification product) also peaked after 1 day and then decreased. Only high levels of nitrite and metHb caused reductions in MO{sub 2max} and U{sub crit}. The response of striped catfish contrasts with that seen in most other fish species and discloses efficient mechanisms of combating nitrite threats. Furthermore, even though striped catfish is an efficient air-breather, this species has the ability to sustain aerobic scope and swimming performance without air-breathing, even when faced with nitrite-induced reductions in blood oxygen carrying capacity. Our study is the first to confirm that high levels of nitrite and metHb reduce MO{sub 2max} and thereby aerobic scope, while more moderate elevations fail to do so. Further studies are needed to elucidate the mechanisms underlying the low nitrite accumulation in striped catfish.

  3. Effects of nitrite exposure on functional haemoglobin levels, bimodal respiration, and swimming performance in the facultative air-breathing fish Pangasianodon hypophthalmus.

    Science.gov (United States)

    Lefevre, Sjannie; Jensen, Frank B; Huong, Do T T; Wang, Tobias; Phuong, Nguyen T; Bayley, Mark

    2011-07-01

    In this study we investigated nitrite (NO₂⁻) effects in striped catfish, a facultative air-breather. Fish were exposed to 0, 0.4, and 0.9 mM nitrite for 0, 1, 2, 4, and 7 days, and levels of functional haemoglobin, methaemoglobin (metHb) and nitrosyl haemoglobin (HbNO) were assessed using spectral deconvolution. Plasma concentrations of nitrite, nitrate, chloride, potassium, and sodium were also measured. Partitioning of oxygen consumption was determined to reveal whether elevated metHb (causing functional hypoxia) induced air-breathing. The effects of nitrite on maximum oxygen uptake (MO(2max)) and critical swimming speed (U(crit)) were also assessed. Striped catfish was highly tolerant to nitrite exposure, as reflected by a 96 h LC₅₀ of 1.65 mM and a moderate nitrite uptake into the blood. Plasma levels of nitrite reached a maximum after 1 day of exposure, and then decreased, never exceeding ambient levels. MetHb, HbNO and nitrate (a nitrite detoxification product) also peaked after 1 day and then decreased. Only high levels of nitrite and metHb caused reductions in MO(2max) and U(crit). The response of striped catfish contrasts with that seen in most other fish species and discloses efficient mechanisms of combating nitrite threats. Furthermore, even though striped catfish is an efficient air-breather, this species has the ability to sustain aerobic scope and swimming performance without air-breathing, even when faced with nitrite-induced reductions in blood oxygen carrying capacity. Our study is the first to confirm that high levels of nitrite and metHb reduce MO(2max) and thereby aerobic scope, while more moderate elevations fail to do so. Further studies are needed to elucidate the mechanisms underlying the low nitrite accumulation in striped catfish. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Effects of nitrite exposure on functional haemoglobin levels, bimodal respiration, and swimming performance in the facultative air-breathing fish Pangasianodon hypophthalmus

    International Nuclear Information System (INIS)

    Lefevre, Sjannie; Jensen, Frank B.; Huong, Do.T.T.; Wang, Tobias; Phuong, Nguyen T.; Bayley, Mark

    2011-01-01

    In this study we investigated nitrite (NO 2 - ) effects in striped catfish, a facultative air-breather. Fish were exposed to 0, 0.4, and 0.9 mM nitrite for 0, 1, 2, 4, and 7 days, and levels of functional haemoglobin, methaemoglobin (metHb) and nitrosyl haemoglobin (HbNO) were assessed using spectral deconvolution. Plasma concentrations of nitrite, nitrate, chloride, potassium, and sodium were also measured. Partitioning of oxygen consumption was determined to reveal whether elevated metHb (causing functional hypoxia) induced air-breathing. The effects of nitrite on maximum oxygen uptake (MO 2max ) and critical swimming speed (U crit ) were also assessed. Striped catfish was highly tolerant to nitrite exposure, as reflected by a 96 h LC 50 of 1.65 mM and a moderate nitrite uptake into the blood. Plasma levels of nitrite reached a maximum after 1 day of exposure, and then decreased, never exceeding ambient levels. MetHb, HbNO and nitrate (a nitrite detoxification product) also peaked after 1 day and then decreased. Only high levels of nitrite and metHb caused reductions in MO 2max and U crit . The response of striped catfish contrasts with that seen in most other fish species and discloses efficient mechanisms of combating nitrite threats. Furthermore, even though striped catfish is an efficient air-breather, this species has the ability to sustain aerobic scope and swimming performance without air-breathing, even when faced with nitrite-induced reductions in blood oxygen carrying capacity. Our study is the first to confirm that high levels of nitrite and metHb reduce MO 2max and thereby aerobic scope, while more moderate elevations fail to do so. Further studies are needed to elucidate the mechanisms underlying the low nitrite accumulation in striped catfish.

  5. Evolution of nitrate and nitrite during the processing of dry-cured ham with partial replacement of NaCl by other chloride salts.

    Science.gov (United States)

    Armenteros, Mónica; Aristoy, María-Concepción; Toldrá, Fidel

    2012-07-01

    Nitrate and nitrite are commonly added to dry-cured ham to provide protection against pathogen microorganisms, especially Clostridium botulinum. Both nitrate and nitrite were monitored with ion chromatography in dry-cured hams salted with different NaCl formulations (NaCl partially replaced by KCl and/or CaCl(2), and MgCl(2)). Nitrate, that is more stable than nitrite, diffuses into the ham and acts as a reservoir for nitrite generation. A correct nitrate and nitrite penetration was detected from the surface to the inner zones of the hams throughout its processing, independently of the salt formulation. Nitrate and nitrite achieved similar concentrations, around 37 and 2.2 ppm, respectively in the inner zones of the ham for the three assayed salt formulations at the end of the process, which are in compliance with European regulations. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. Amperometric nitrite sensor based on a glassy carbon electrode modified with multi-walled carbon nanotubes and poly(toluidine blue)

    International Nuclear Information System (INIS)

    Dai, Juan; Deng, Fei; He, Shuang; Deng, Dongli; Yuan, Yali; Zhang, Jinzhong

    2016-01-01

    An amperometric nitrite sensor modified with multi-walled carbon nanotubes (MWCNTs) and poly(toluidine blue) (PTB) on glassy carbon electrode was constructed. The surface morphology of the composite- modified electrode was characterized by scanning electron microscopy, and the electrochemical response behavior and electrocatalytic oxidation mechanism of nitrite were investigated by cyclic voltammetry. The high surface-to-volume ratio of MWCNTs and PTB brings the electrochemical sensing unit and nitrite in full contact. This renders the electrochemical response extremely sensitive to nitrite. Under the optimal measurement conditions and a working voltage of 0.73 V (vs. SCE), a linear relationship is obtained between the oxidation peak current and nitrite concentration in the range of 39 nM–1.1 mM, and the limit of detection is lowered to 19 nM (at an S/N ratio of 3). The sensor was successfully applied to the determination of nitrite in greenhouse soils. (author)

  7. In vitro effect of sodium nitrite on platelet aggregation in human platelet rich plasma--preliminary report.

    Science.gov (United States)

    Kadan, M; Doğanci, S; Yildirim, V; Özgür, G; Erol, G; Karabacak, K; Avcu, F

    2015-10-01

    The role of nitrates and nitric oxide on platelet functions has obtained an increasing attention with respect to their potential effects on cardiovascular disorders. In this study we aimed to analyze the effect of sodium nitrite on platelet functions in human platelets. This in vitro study was designed to show the effect of sodium nitrite on platelet functions in seven healthy volunteers. Blood samples were centrifuged to prepare platelet rich plasma and platelet poor plasma. Platelet rich plasma was diluted with the platelet poor plasma to have a final count of 300,000 ± 25,000 platelets. Platelet rich plasma was incubated with six different increasing doses (from 10 μM to 5 mM) of sodium nitrite for 1 hour at 37°C. Then stimulating agents including collagen (3 μg ml-1), adenosine diphosphate (10 μM), and epinephrine (10 μM) were added to the cuvette. Changes in light transmission were observed for 10 minutes. In addition spontaneous aggregation were performed in control group with all aggregating agents separately. Effect of sodium nitrite on agonist-induced platelet aggregation depends on the concentration of sodium nitrite. Compared with control group, agonist-induced platelet aggregations were significantly suppressed by sodium nitrite at the concentration of 5, 1.0 and 0.5 mM. Our results suggested that sodium nitrite has inhibitory effects in vitro on platelet aggregation in a dose-dependent manner.

  8. Daily Intake of Protein from Cod Residual Material Lowers Serum Concentrations of Nonesterified Fatty Acids in Overweight Healthy Adults: A Randomized Double-Blind Pilot Study

    Directory of Open Access Journals (Sweden)

    Iselin Vildmyren

    2018-06-01

    Full Text Available Improved process technologies have allowed fishing vessels to utilize residuals from cod fillet production (head, backbone, skin, cuttings, and entrails and convert this to high-quality protein powders for human consumption. In this double-blind pilot study, 42 healthy overweight or obese adults were randomized to three experimental groups consuming tablets corresponding to 6 g/day of proteins from cod residuals as presscake meal (Cod-PC, presscake and stickwater meal (Cod-PCW, or placebo tablets (control for eight weeks. The primary outcome of this study was changes in metabolites related to glucose regulation in overweight or obese healthy adults after intake of proteins from cod residuals. Cod-PC supplementation decreased postprandial serum nonesterified fatty acids (NEFA concentration and increased gene expressions of diglyceride acyltransferase 1 and 2 in subcutaneous adipose tissue compared with controls. Fasting insulin increased while fasting NEFA and 120-min postprandial glucose decreased within the Cod-PC group, but these changes did not differ from the other groups. In conclusion, supplementation with Cod-PC beneficially affected postprandial serum NEFA concentration compared with the other groups in overweight or obese adults. Supplementation with Cod-PCW, which contains a higher fraction of water-soluble protein compared to Cod-PC, did not affect serum markers of glucose regulation.

  9. Nitrates and nitrites in selected vegetables purchased at supermarkets in Siedlce, Poland.

    Science.gov (United States)

    Raczuk, Jolanta; Wadas, Wanda; Głozak, Katarzyna

    2014-01-01

    Vegetables constitute a vital part of the human diet, being the main source of minerals, vitamins, dietary fibre and phytochemicals. They however, also contain nitrates and nitrites, which adversely affect human health. To determine nitrate and nitrite content in selected vegetables purchased at supermarket chains in Siedlce and to assess their impact on consumer health. Vegetable samples were purchased from local supermarkets in Siedlce, town situated in the Mazovian province (Voivodeship) of Poland. These consisted of 116 samples of nine vegetables types including butterhead and iceberg lettuce, beetroot, white cabbage, carrot, cucumber, radish, tomato and potato collected between April and September 2011. Concentrations of nitrate and nitrite were determined by standard colorimetric methods used in Poland, with results expressed as mg per kg fresh weight of vegetables. Nitrate concentrations varied between 10 mg x kg(-1) to 4800 mg x kg(-1). The highest mean nitrate concentrations were found in radishes (2132 mgkg(-1)), butterhead lettuce (1725 mg x kg(-1)), beetroots (1306 mg x kg(-1)) and iceberg lettuce (890 mg x kg(-1)), whereas the lowest were found in cucumber (32 mg x kg(-1)) and tomato (35 mg x kg(-1)). Nitrite levels were also variable; the highest concentrations measured were in beetroot (mean 9.19 mg x kg(-1)) whilst much smaller amounts were present in carrot, cucumbers, iceberg lettuce, white cabbage, tomatoes and potatoes. The daily adult consumption of 100 g amounts of the studied vegetables were found not exceed the ADI for both nitrates and nitrites. Findings indicated the need for monitoring nitrate and nitrite content in radishes, butterhead lettuce and beetroot due to consumer health concerns.

  10. Nitrite reduction mechanism on a Pd surface.

    Science.gov (United States)

    Shin, Hyeyoung; Jung, Sungyoon; Bae, Sungjun; Lee, Woojin; Kim, Hyungjun

    2014-11-04

    Nitrate (NO3-) is one of the most harmful contaminants in the groundwater, and it causes various health problems. Bimetallic catalysts, usually palladium (Pd) coupled with secondary metallic catalyst, are found to properly treat nitrate-containing wastewaters; however, the selectivity toward N2 production over ammonia (NH3) production still requires further improvement. Because the N2 selectivity is determined at the nitrite (NO2-) reduction step on the Pd surface, which occurs after NO3- is decomposed into NO2- on the secondary metallic catalyst, we here performed density functional theory (DFT) calculations and experiments to investigate the NO2- reduction pathway on the Pd surface activated by hydrogen. Based on extensive DFT calculations on the relative energetics among ∼100 possible intermediates, we found that NO2- is easily reduced to NO* on the Pd surface, followed by either sequential hydrogenation steps to yield NH3 or a decomposition step to N* and O* (an adsorbate on Pd is denoted using an asterisk). Based on the calculated high migration barrier of N*, we further discussed that the direct combination of two N* to yield N2 is kinetically less favorable than the combination of a highly mobile H* with N* to yield NH3. Instead, the reduction of NO2- in the vicinity of the N* can yield N2O* that can be preferentially transformed into N2 via diverse reaction pathways. Our DFT results suggest that enhancing the likelihood of N* encountering NO2- in the solution phase before combination with surface H* is important for maximizing the N2 selectivity. This is further supported by our experiments on NO2- reduction by Pd/TiO2, showing that both a decreased H2 flow rate and an increased NO2- concentration increased the N2 selectivity (78.6-93.6% and 57.8-90.9%, respectively).

  11. Carbon-Fiber Nitrite Microsensor for In Situ Biofilm Monitoring

    Science.gov (United States)

    During nitrification, nitrite is produced as an intermediate when ammonia is oxidized to nitrate. It is well established that nitrifying biofilm are involved in nitrification episodes in chloraminated drinking water distribution systems with nitrite accumulation occurring during ...

  12. The steady-state kinetics of the NADH-dependent nitrite reductase from Escherichia coli K 12. Nitrite and hydroxylamine reduction.

    OpenAIRE

    Jackson, R H; Cole, J A; Cornish-Bowden, A

    1981-01-01

    The reduction of both NO2- and hydroxylamine by the NADH-dependent nitrite reductase of Escherichia coli K 12 (EC 1.6.6.4) appears to follow Michaelis-Menten kinetics over a wide range of NADH concentrations. Substrate inhibition can, however, be detected at low concentrations of the product NAD+. In addition, NAD+ displays mixed product inhibition with respect to NADH and mixed or uncompetitive inhibition with respect to hydroxylamine. These inhibition characteristics are consistent with a m...

  13. Further studies on the use of enzyme profiles to monitor residue accumulation in wildlife: Plasma enzymes in starlings fed graded concentrations of morsodren, DDE, Aroclor 1254, and malathion

    Science.gov (United States)

    Dieter, M.P.

    1975-01-01

    Wild-trapped starlings (Sturnus vulgaris) were fed concentrations of Morsodren (2, 4, and 8 ppm), DDE or Aroclor 1254 (5, 25, and 100 ppm), or malathion (8, 35, and 160 ppm) that were found to be sublethal in pen-reared Coturnix quail fed these amounts for 12 weeks. Plasma enzymes had to be measured earlier than planned in starlings fed Morsodren (at three weeks) or the organochlorine compounds (at seven weeks) because of unexpected, subsequent mortality. Variations in enzyme response were greater in wild than in pen-reared birds, but not enough to mask the toxicant-induced changes in enzyme activity. Cholinesterase activities decreased in birds fed Morsodren or malathion, and increased in those fed the organochlorine compounds. Lactate dehydrogenase activities increased two-fold in starlings fed Morsodren and two- to four-fold in those fed the organochlorine compounds, but only 50% in those fed malathion. Further examination of enzyme profiles showed that creatine kinase and aspartate aminotransferase activities increased two-to four-fold in birds fed Morsodren or the organochlorine compounds but not at all in those fed malathion. Thus the classes of environmental contaminants fed to starlings could be easily distinguished by these enzymatic parameters. Evaluation of enzymatic profiles appears to be a potentially valuable technique to monitor the presence of toxicants in wild populations, especially if used to complement standard chemical residue analyses. Here the residue analyses showed, after three weeks feeding, that mercury in the carcasses reflected the concentrations fed daily, whereas accumulation in the livers was two- to four-fold greater. After seven weeks feeding, liver residues of either organochlorine compound were about three-fold higher than the concentrations fed daily. However, four times as much DDE as Aroclor 1254 had accumulated in the carcasses.

  14. STUDY ON DECREASE OF NITRITE AND NITRATE USAGE IN PROCESSED MEAT WITH ADDITION OF NATURAL SALT AND CARBON MONOXIDE

    Directory of Open Access Journals (Sweden)

    R. Sakata

    2017-01-01

    Full Text Available This study was carried out to examine the reddening of meat products due to the addition of natural yellow salt (YS and carbon monoxide (CO. Following YS or NaCl addition at 2% to pork subsequent to nitrite (0~100 ppm treatment, color development due to this addition was analyzed optically. Heme pigment content in the meat was also determined spectrophotometrically. YS was found to bring about greater reddening than NaCl, indicating residual nitrite and nitrate content to be significantly higher in meat containing YS, through the amount of either was quite small. The nitrite itself in YS could never explain the color formation by the YS. Because the YS included not only nitrite but also nitrate, the effects of nitrate on the color stability of cooked cured pork were examined. Nitrate inhibited the nitrite decrement and discoloration in the cooked cured ham. The degradation rate of nitrite was clearly found to decrease with nitric acid content. Nitrate does not appear to serve as a donor of nitrite, but rather inhibits nitrite reduction in cooked meat products, with consequent prolongation of color stability. Nitrate, observed in many rock salt and also in this case, could enhance the color formation. CO treatment of pork caused the formation of carboxy myoglobin (COMb with consequent reddening of the meat. COMb was shown to be heat-stable and form stably at pH 5.0 to 8.0 and to be extractable with water, but was barely extractable at all with acetone. Nitric oxide was found to have greater affinity toward myoglobin (Mb than CO. Nitrosyl Mb was noted to be stable in all meat products examined. CO was seen to be capable of controlling the extent of lipid oxidation.

  15. Concentration-Response and Residual Activity of Insecticides to Control Herpetogramma phaeopteralis (Lepidoptera: Crambidae) in St. Augustinegrass.

    Science.gov (United States)

    Tofangsazi, Nastaran; Cherry, Ron H; Beeson, Richard C; Arthurs, Steven P

    2015-04-01

    Tropical sod webworm, Herpetogramma phaeopteralis Guenée, is an important pest of warm-season turfgrass in the Gulf Coast states of the United States, the Caribbean Islands, and Central America. Current control recommendations rely on topical application of insecticides against caterpillars. The objective of this study was to generate resistance baseline data of H. phaeopteralis to six insecticide classes. Residual activity of clothianidin, chlorantraniliprole, and bifenthrin was also compared under field conditions in Central Florida. Chlorantraniliprole was the most toxic compound tested (LC50 value of 4.5 ppm), followed by acephate (8.6 ppm), spinosad (31.1 ppm), clothianidin (46.6 ppm), bifenthrin (283 ppm) and Bacillus thuringiensis kurstaki, (342 ppm). In field tests, all compounds at label rates were effective (≥94% mortality of larvae exposed to fresh residues). However, a more rapid decline in activity of clothianidin and bifenthrin was observed compared with chlorantraniliprole. Clothianidin had no statistically detectable activity after 4 wk post-application in spring and the fall, and bifenthrin had no detectable activity after 3 wk in the spring and the fall. However, chlorantraniliprole maintained significant activity (≥84% mortality) compared with other treatments throughout the 5-wk study period. This study provides new information regarding the relative toxicities and persistence of current insecticides used for H. phaeopteralis and other turfgrass caterpillars. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  16. Electrochemical Determination of Food Preservative Nitrite with Gold Nanoparticles/p-Aminothiophenol-Modified Gold Electrode.

    Science.gov (United States)

    Üzer, Ayşem; Sağlam, Şener; Can, Ziya; Erçağ, Erol; Apak, Reşat

    2016-08-02

    Due to the negative impact of nitrate and nitrite on human health, their presence exceeding acceptable levels is not desired in foodstuffs. Thus, nitrite determination at low concentrations is a major challenge in electroanalytical chemistry, which can be achieved by fast, cheap, and safe electrochemical sensors. In this work, the working electrode (Au) was functionalized with p-aminothiophenol (p-ATP) and modified with gold nanoparticles (Au-NPs) to manufacture the final (Au/p-ATP-Aunano) electrode in a two-step procedure. In the first step, p-ATP was electropolymerized on the electrode surface to obtain a polyaminothiophenol (PATP) coating. In the second step, Au/p-ATP-Aunano working electrode was prepared by coating the surface with the use of HAuCl₄ solution and cyclic voltammetry. Determination of aqueous nitrite samples was performed with the proposed electrode (Au/p-ATP-Aunano) using square wave voltammetry (SWV) in pH 4 buffer medium. Characteristic peak potential of nitrite samples was 0.76 V, and linear calibration curves of current intensity versus concentration was linear in the range of 0.5-50 mg·L(-1) nitrite with a limit of detection (LOD) of 0.12 mg·L(-1). Alternatively, nitrite in sausage samples could be colorimetrically determined with high sensitivity by means of p-ATP‒modified gold nanoparticles (AuNPs) and naphthylethylene diamine as coupling agents for azo-dye formation due to enhanced charge-transfer interactions with the AuNPs surface. The slopes of the calibration lines in pure NO₂(-) solution and in sausage sample solution, to which different concentrations of NO₂(-) standards were added, were not significantly different from each other, confirming the robustness and interference tolerance of the method. The proposed voltammetric sensing method was validated against the colorimetric nanosensing method in sausage samples.

  17. Gamma exposure rate reduction and residual radium-226 concentrations resulting from decontamination activities conducted at the former uranium millsite in Shiprock, New Mexico

    International Nuclear Information System (INIS)

    Hans, J.M. Jr.; Hurst, T.L.

    1981-01-01

    Gamma radiation surveys and residual radium 226 soil samples were taken as part of the decontamination activities of the former Shiprock uranium mill site in New Mexico. In order to facilitate the decontamination activities, the mill site and its contaminated environs were divided into 6 major areas. Extensive data are presented in 2 appendices of the pre- and post-decontamination gamma ray exposure rates made on mill site, and of radium 226 concentrations in surface soil samples. A training program established on the mill site by the Navajo Engineering and Construction Authority is described

  18. Organochlorine residues in harp seals, Phoca groenlandica, from the Gulf of St. Lawrence and Hudson Strait: An evaluation of contaminant concentrations and burdens

    Energy Technology Data Exchange (ETDEWEB)

    Beck, G.G.; Smith, T.G. (Dept. of Fisheries and Oceans, Nanaimo, BC (Canada)); Addison, R.F. (Dept. of Fisheries and Oceans, Sidney, BC (Canada))

    1994-01-01

    Organochlorine contaminant concentrations and burdens were evaluated in blubber samples from 50 harp seals (Phoca groenlandica) obtained from the estuary and northern Gulf of St. Lawrence and Hudson Strait, Canada between December 1988 and December 1989. The concentration and burden of polychlorinated biphenyls (PCBs) increased significantly during the winter months for males occupying the St. Lawrence estuary. The potential for rapid accumulation of contaminants in the estuary was also observed among females: nine postpartum females (1 month after weaning) had higher organochlorine levels than prepartum females from the same location. The lowest observed contaminant concentrations and burdens were in seals from Hudson Strait in autumn. In winter specimens, males had DDT and PCB concentrations about 4 and 2 times as great, respectively, as females of similar age distribution and collection date. Congeners with IUPAC Nos. 138 and 153 accounted for more than 50% of total identifiable PCBs, which is consistent with their prevalence in other marine biota. The concentration of PCBs has declined and the percent p,p'-DDE of total DDT has increased between 1982 and the present study. Unlike the beluga whale (Delphinapterus leucas), harp seals occupy the more polluted waters of the estuary only seasonally, and this may account for their lower residue concentrations. 59 refs., 1 fig., 5 tabs.

  19. 9 CFR 319.2 - Products and nitrates and nitrites.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Products and nitrates and nitrites... and nitrates and nitrites. Any product, such as frankfurters and corned beef, for which there is a standard in this part and to which nitrate or nitrite is permitted or required to be added, may be prepared...

  20. 40 CFR 721.4740 - Alkali metal nitrites.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkali metal nitrites. 721.4740... Substances § 721.4740 Alkali metal nitrites. (a) Chemical substances and significant new use subject to reporting. (1) The category of chemical substances which are nitrites of the alkali metals (Group IA in the...

  1. A new system for the spectrophotometric determination of trace amounts of nitrite in environmental samples

    Directory of Open Access Journals (Sweden)

    Cherian Tom

    2006-01-01

    Full Text Available A selective and rapid spectrophotometric method for the determination of nitrite is presented. It is based on the reaction of nitrite with p-nitroaniline in acid medium to form diazonium ion, which is coupled with ethoxyethylenemaleic ester or ethylcyanoacetate in basic medium to form azo dyes, showing absorption maxima at 439 and 465 nm respectively. The method obeys Beer's law in the concentration range of 0.5-16 µg mL-1 of nitrite with ethoxyethylenemaleic ester and 0.2-18 µg mL-1 of nitrite with ethylcyanoacetate. The molar absorptivity and Sandell's sensitivity of p-nitroaniline-ethoxyethylenemaleic ester and p-nitroaniline-ethylcyanoacetate azo dyes are 5.04 X 10(4 L mol-1cm-1, 0.98 X 10-2 µg cm-2 and 1.21 X 10(4 L mol-1 cm-1, 0.98 X 10-2 µg cm-2 respectively. The optimum reaction conditions and other analytical parameters were evaluated. The method was successfully applied to the determination of nitrite in various water samples and soil samples.

  2. Sensitive paper-based analytical device for fast colorimetric detection of nitrite with smartphone.

    Science.gov (United States)

    Zhang, Xiu-Xiu; Song, Yi-Zhen; Fang, Fang; Wu, Zhi-Yong

    2018-04-01

    On-site rapid monitoring of nitrite as an assessment indicator of the environment, food, and physiological systems has drawn extensive attention. Here, electrokinetic stacking (ES) was combined with colorimetric reaction on a paper-based device (PAD) to achieve colorless nitrite detection with smartphone. In this paper, nitrite was stacked on the paper fluidic channel as a narrow band by electrokinetic stacking. Then, Griess reagent was introduced to visualize the stacking band. Under optimal conditions, the sensitivity of nitrite was 160-fold increased within 5 min. A linear response in the range of 0.075 to 1.0 μg mL -1 (R 2  = 0.99) and a limit of detection (LOD) of 73 ng mL -1 (0.86 μM) were obtained. The LOD was 10 times lower than the reported PAD, and close to that achieved by a desktop spectrophotometer. The applicability was demonstrated by nitrite detection from saliva and water with good selectivity, adding 100 times more concentrated co-ions. High recovery (91.0~108.7%) and reasonable intra-day and inter-day reproducibility (RSD work shows that the sensitivity of colorless analyte detection-based colorimetric reaction can be effectively enhanced by integration of ES on a PAD. Graphical abstract Schematic of the experimental setups (left) and the corresponding images (right) of the actual portable device.

  3. Isolation of Ochrobactrum sp.QZ2 from sulfide and nitrite treatment system

    International Nuclear Information System (INIS)

    Mahmood, Qaisar; Hu Baolan; Cai Jing; Zheng Ping; Azim, Muhammad Rashid; Jilani, Ghulam; Islam, Ejazul

    2009-01-01

    A bacterial strain QZ2 was isolated from sludge of anoxic sulfide-oxidizing (ASO) reactor. Based on 16S rDNA sequence analysis and morphology, the isolate was identified as Ochrobactrum sp. QZ2. The strain was facultative chemolithotroph, able of using sulfide to reduce nitrite anaerobically. It produced either elemental sulfur or sulfate as the product of sulfide oxidation, depending on the initial sulfide and nitrite concentrations. The optimum growth pH and temperature for Ochrobactrum sp. QZ2 were found as 6.5-7.0 and 30 deg. C, respectively. The specific growth rate (μ) was found as 0.06 h -1 with a doubling time of 19.75 h; the growth seemed more sensitive to highly alkaline pH. Ochrobactrum sp. QZ2 catalyzed sulfide oxidation to sulfate was more sensitive to sulfide compared with nitrite as indicated by IC 50 values for sulfide and nitrite utilization implying that isolate was relatively more tolerant to nitrite. The comparison of physiology of Ochrobactrum sp. QZ2 with those of other known sulfide-oxidizing bacteria suggested that the present isolate resembled to Ochrobactrum anthropi in its denitrification ability.

  4. SPECTROPHOTOMETRIC DETERMINATION OF NITRITE BY ITS ...

    African Journals Online (AJOL)

    Preferred Customer

    sources of nitrite include intensive use of chemical nitrogenous fertilizers, ... The current paper describes another kinetic spectrophotometric method for determination of ... s at λmax = 570 nm (allowing a lag time of 5 s) against water as reference. ... samples and the total amount of the analyte was estimated by applying the ...

  5. 21 CFR 172.175 - Sodium nitrite.

    Science.gov (United States)

    2010-04-01

    ... preservative and color fixative, with sodium nitrate, in meat-curing preparations for the home curing of meat and meat products (including poultry and wild game), with directions for use which limit the amount of sodium nitrite to not more than 200 parts per million in the finished meat product, and the amount of...

  6. 21 CFR 573.700 - Sodium nitrite.

    Science.gov (United States)

    2010-04-01

    ..., FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive... as a preservative and color fixative in canned pet food containing fish, meat, and fish and meat... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Sodium nitrite. 573.700 Section 573.700 Food and...

  7. Nitrite maxima in the Northern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Sankaranarayanan, V.N.; DeSousa, S.N.; Fondekar, S.P.

    There are 2 nitrite maxima in the Northern Arabian Sea, one at the thermocline depth and the other at depths between 300 and 500 m. The 2nd maximum is more prominent in the northeastern part of the Arabian Sea. The 1st maximum is associated...

  8. Neutralization of wastewater from nitrite passivation

    International Nuclear Information System (INIS)

    Pawlowski, L.; Mientki, B.; Wasag, H.

    1982-01-01

    A method for neutralization of wastewater formed in nitrite passivation has been presented. The method consists of introducing urea into wastewater and acidifying it with sulphuric acid. Wastewater is neutralized with lime. After clarification, wastewater can be drained outside the plant

  9. Biosensor for laboratory and lander-based analysis of benthicnitrate plus nitrite distribution in marine environments

    DEFF Research Database (Denmark)

    Revsbech, N. P.; Glud, Ronnie Nøhr

    2009-01-01

    We present a psychotropic bacteria–based biosensor that can be used in low–temperature seawater for the analysis of nitrate + nitrite (NOx –). The sensor can be used to resolve concentrations below 1 µmol L–1 at low temperature (

  10. The nitrite-oxidizing community in activated sludge from a municipal wastewater treatment plant determined by fatty acid methyl ester-stable isotope probing.

    Science.gov (United States)

    Kruse, Myriam; Zumbrägel, Sabine; Bakker, Evert; Spieck, Eva; Eggers, Till; Lipski, André

    2013-10-01

    Metabolically-active autotrophic nitrite oxidizers from activated sludge were labeled with (13)C-bicarbonate under exposure to different temperatures and nitrite concentrations. The labeled samples were characterized by FAME-SIP (fatty acid methyl ester-stable isotope probing). The compound cis-11-palmitoleic acid, which is the major lipid of the most abundant nitrite oxidizer in activated sludge, Candidatus Nitrospira defluvii, showed (13)C-incorporation in all samples exposed to 3 mM nitrite. Subsequently, the lipid cis-7-palmitoleic acid was labeled, and it indicated the activity of a nitrite oxidizer that was different from the known Nitrospira taxa in activated sludge. The highest incorporation of cis-7-palmitoleic acid label was found after incubation with a nitrite concentration of 0.3 mM at 17 and 22°C. While activity of Nitrobacter populations could not be detected by the FAME-SIP approach, an unknown nitrite oxidizer with the major lipid cis-9 isomer of palmitoleic acid exhibited (13)C-incorporation at 28°C with 30 mM nitrite. These results indicated flexibility of nitrite-oxidizing guilds in a complex community responding to different conditions. Labeled lipids so far not described for activated sludge-associated nitrifiers indicated the presence of unknown nitrite oxidizers in this habitat. The FAME-SIP-based information can be used to define appropriate conditions for the enrichment of nitrite-oxidizing guilds from complex samples. Copyright © 2013 Elsevier GmbH. All rights reserved.

  11. Enhanced primary treatment of concentrated black water and kitchen residues within DESAR concept using two types of anaerobic digesters

    NARCIS (Netherlands)

    Kujawa-Roeleveld, K.; Elmitwalli, T.A.; Zeeman, G.

    2006-01-01

    Anaerobic digestion of concentrated domestic wastewater streams - black or brown water, and solid fraction of kitchen waste is considered as a core technology in a source separation based sanitation concept (DESAR - decentralised sanitation and reuse). A simple anaerobic digester can be implemented

  12. Pesticide residue concentration in soil following conventional and Low-Input Crop Management in a Mediterranean agro-ecosystem, in Central Greece

    Energy Technology Data Exchange (ETDEWEB)

    Karasali, Helen, E-mail: e.karassali@bpi.gr [Laboratory of Chemical Control of Pesticides, Department of Pesticides Control and Phytopharmacy, Benaki Phytopathological Institute, 8 St. Delta Street, Kifissia, 14561 Athens (Greece); Marousopoulou, Anna [Laboratory of Chemical Control of Pesticides, Department of Pesticides Control and Phytopharmacy, Benaki Phytopathological Institute, 8 St. Delta Street, Kifissia, 14561 Athens (Greece); Machera, Kyriaki, E-mail: k.machera@bpi.gr [Laboratory of Pesticides Toxicology, Department of Pesticides Control and Phytopharmacy, Benaki Phytopathological Institute, 8 St. Delta Street, Kifissia, 14561 Athens (Greece)

    2016-01-15

    The present study was focused on the comparative evaluation of pesticide residues, determined in soil samples from Kopaida region, Greece before and after the implementation of Low-Input Crop Management (LCM) protocols. LCM has been suggested as an environmental friendly plant protection approach to be applied on crops growing in vulnerable to pollution ecosystems, with special focus on the site specific problems. In the case of the specific pilot area, the vulnerability was mainly related to the pollution of water bodies from agrochemicals attributed to diffuse pollution primarily from herbicides and secondarily from insecticides. A total of sixty-six soil samples, were collected and analyzed during a three-year monitoring study and the results of the determined pesticide residues were considered for the impact evaluation of applied plant protection methodology. The LCM was developed and applied in the main crops growing in the pilot area i.e. cotton, maize and industrial tomato. Herbicides active ingredients such as ethalfluralin, trifluralin, pendimethalin, S-metolachlor and fluometuron were detected in most samples at various concentrations. Ethalfluralin, which was the active ingredient present in the majority of the samples ranged from 0.01 μg g{sup −1} to 0.26 μg g{sup −1} soil dry weight. However, the amount of herbicides measured after the implementation of LCM for two cropping periods, was reduced by more than 75% in all cases. The method of analysis was based on the simultaneous extraction of the target compounds by mechanical shaking, followed by liquid chromatography mass spectrometric and gas chromatography electron capture (LC–MS/MS and GC–ECD) analysis. - Highlights: • Effect of Low Input Crop Management (LCM) in a vulnerable to pollution ecosystem. • LCM resulted in herbicide residues reduction in the range of 75 and 100% in all cases. • Conventional practices resulted in increased herbicide residues up to 18%. • Anthropogenic

  13. Effect of leaching residual methyl methacrylate concentrations on in vitro cytotoxicity of heat polymerized denture base acrylic resin processed with different polymerization cycles

    Directory of Open Access Journals (Sweden)

    Canan Bural

    2011-08-01

    Full Text Available OBJECTIVES: Residual methyl methacrylate (MMA may leach from the acrylic resin denture bases and have adverse effects on the oral mucosa. This in vitro study evaluated and correlated the effect of the leaching residual MMA concentrations ([MMA]r on in vitro cytotoxicity of L-929 fibroblasts. MATERIAL AND METHODS: A total of 144 heat-polymerized acrylic resin specimens were fabricated using 4 different polymerization cycles: (1 at 74ºC for 9 h, (2 at 74ºC for 9 h and terminal boiling (at 100ºC for 30 min, (3 at 74ºC for 9 h and terminal boiling for 3 h, (4 at 74ºC for 30 min and terminal boiling for 30 min. Specimens were eluted in a complete cell culture medium at 37ºC for 1, 2, 5 and 7 days. [MMA]r in eluates was measured using high-performance liquid chromatography. In vitro cytotoxicity of eluates on L-929 fibroblasts was evaluated by means of cell proliferation using a tetrazolium salt XTT (sodium 3´-[1-phenyl-aminocarbonyl-3,4-tetrazolium]bis(4-methoxy-6-nitrobenzenesulphonic acid assay. Differences in [MMA]r of eluates and cell proliferation values between polymerization cycles were statistically analyzed by Kruskal-Wallis, Friedman and Dunn's multiple comparison tests. The correlation between [MMA]r of eluates and cell proliferation was analyzed by Pearson's correlation test (p<0.05. RESULTS: [MMA]r was significantly (p<0.001 higher in eluates of specimens polymerized with cycle without terminal boiling after elution of 1 and 2 days. Cell proliferation values for all cycles were significantly (p<0.01 lower in eluates of 1 day than those of 2 days. The correlation between [MMA]r and cell proliferation values was negative after all elution periods, showing significance (p<0.05 for elution of 1 and 2 days. MMA continued to leach from acrylic resin throughout 7 days and leaching concentrations markedly reduced after elution of 1 and 2 days. CONCLUSION: Due to reduction of leaching residual MMA concentrations, use of terminal boiling in

  14. Construction of a predictive model for concentration of nickel and vanadium in vacuum residues of crude oils using artificial neural networks and LIBS.

    Science.gov (United States)

    Tarazona, José L; Guerrero, Jáder; Cabanzo, Rafael; Mejía-Ospino, E

    2012-03-01

    A predictive model to determine the concentration of nickel and vanadium in vacuum residues of Colombian crude oils using laser-induced breakdown spectroscopy (LIBS) and artificial neural networks (ANNs) with nodes distributed in multiple layers (multilayer perceptron) is presented. ANN inputs are intensity values in the vicinity of the emission lines 300.248, 301.200 and 305.081 nm of the Ni(I), and 309.310, 310.229, and 311.070 nm of the V(II). The effects of varying number of nodes and the initial weights and biases in the ANNs were systematically explored. Average relative error of calibration/prediction (REC/REP) and average relative standard deviation (RSD) metrics were used to evaluate the performance of the ANN in the prediction of concentrations of two elements studied here. © 2012 Optical Society of America

  15. Temporal variation of persistent organic pollutant (POP) residue concentrations in sediments from the bay of Chetumal, Mexico.

    Science.gov (United States)

    Noreña-Barroso, E; Gold-Bouchot, G; Ceja-Moreno, V

    2007-08-01

    Bay of Chetumal is a transboundary priority area for the Mesoamerican Barrier Reef Systems project, which has been studied because it is the receiving body of pollutants from a large agricultural area and the city of Chetumal. Levels of persistent organic pollutants in sediments from the Bay were assessed a few years after a mass mortality event of Mayan catfish (Ariopsis assimilis) occurred in 1996. Recent sediments were collected in the rainy season (1999) and dry season (2000); results show concentrations in general lower than those reported after the fish kill, and a change of chemical profiles in chemical pollution.

  16. Nitrite accumulation from simultaneous free-ammonia and free-nitrous-acid inhibition and oxygen limitation in a continuous-flow biofilm reactor.

    Science.gov (United States)

    Park, Seongjun; Chung, Jinwook; Rittmann, Bruce E; Bae, Wookeun

    2015-01-01

    To achieve nitrite accumulation for shortcut biological nitrogen removal (SBNR) in a biofilm process, we explored the simultaneous effects of oxygen limitation and free ammonia (FA) and free nitrous acid (FNA) inhibition in the nitrifying biofilm. We used the multi-species nitrifying biofilm model (MSNBM) to identify conditions that should or should not lead to nitrite accumulation, and evaluated the effectiveness of those conditions with experiments in continuous flow biofilm reactors (CFBRs). CFBR experiments were organized into four sets with these expected outcomes based on the MSNBM as follows: (i) Control, giving full nitrification; (ii) oxygen limitation, giving modest long-term nitrite build up; (iii) FA inhibition, giving no long-term nitrite accumulation; and (iv) FA inhibition plus oxygen limitation, giving major long-term nitrite accumulation. Consistent with MSNBM predictions, the experimental results showed that nitrite accumulated in sets 2-4 in the short term, but long-term nitrite accumulation was maintained only in sets 2 and 4, which involved oxygen limitation. Furthermore, nitrite accumulation was substantially greater in set 4, which also included FA inhibition. However, FA inhibition (and accompanying FNA inhibition) alone in set 3 did not maintained long-term nitrite accumulation. Nitrite-oxidizing bacteria (NOB) activity batch tests confirmed that little NOB or only a small fraction of NOB were present in the biofilms for sets 4 and 2, respectively. The experimental data supported the previous modeling results that nitrite accumulation could be achieved with a lower ammonium concentration than had been required for a suspended-growth process. Additional findings were that the biofilm exposed to low dissolved oxygen (DO) limitation and FA inhibition was substantially denser and probably had a lower detachment rate. © 2014 Wiley Periodicals, Inc.

  17. Forensic analysis of high explosives residues in post-blast water samples employing solid phase extraction for analyte pro-concentration

    International Nuclear Information System (INIS)

    Umi Kalsom Ahmad; Rajendran, Sumathy; Ling, Lee Woan

    2008-01-01

    Nitro aromatic, nitramine and nitrate ester compounds are a major group of high order explosive or better known as military explosives. Octahydro-1,3,5,7-tetrazocine (HMX), 1,3,5-hexahydro-1,3,5-trinitro triazine (RDX), 2,4,6-trinitro-toluene (TNT), pentaerythritol tetranitrate (PETN) and 2,4-dinitrotoluene (2,4-DNT) are secondary high explosives classified as most commonly used explosives components. There is an increasing demand for pre-concentration of these compounds in water samples as the sensitivity achieved by instrumental analytical methods for these high explosives residues are the main drawback in the application at trace levels for forensic analysis. Hence, a simple cartridge solid phase extraction (SPE) procedure was optimized as the off-line extraction and pre-concentration method to enhance the detection limit of high explosive residues using micellar electrokinetic chromatography (MEKC) and gas chromatography with electron-capture detection (GC-ECD) methods. The SPE cartridges utilized LiChrolut EN as the SPE adsorbent. By emplying pre-concentration using SPE, the detection limits of the target analytes in water sample were lowered by more than 1000 times with good percentage recovery (>87%) for MEKC method and lowered by 120 times with more than 2 % percentage recovery for GC-ECD methods. In order to test the feasibility of the developed method to real cases, post-blast water samples were analyzed. The post-blast water samples which were collected from Baling Bom training range, Ulu Kinta, Perak contained RDX and PETN in the range of 0.05 - 0.17 ppm and 0.0124 - 0.0390 ppm respectively. (author)

  18. Oxidative stress and nitrite dynamics under maximal load in elite athletes: relation to sport type.

    Science.gov (United States)

    Cubrilo, Dejan; Djordjevic, Dusica; Zivkovic, Vladimir; Djuric, Dragan; Blagojevic, Dusko; Spasic, Mihajlo; Jakovljevic, Vladimir

    2011-09-01

    Maximal workload in elite athletes induces increased generation of reactive oxygen/nitrogen species (RONS) and oxidative stress, but the dynamics of RONS production are not fully explored. The aim of our study was to examine the effects of long-term engagement in sports with different energy requirements (aerobic, anaerobic, and aerobic/anaerobic) on oxidative stress parameters during progressive exercise test. Concentrations of lactates, nitric oxide (NO) measured through stabile end product-nitrites (NO(2) (-)), superoxide anion radical (O(2) (•-)), and thiobarbituric reactive substances (TBARS) as index of lipid peroxidation were determined in rest, after maximal workload, and at 4 and 10th min of recovery in blood plasma of top level competitors in rowing, cycling, and taekwondo. Results showed that sportmen had similar concentrations of lactates and O(2) (•-) in rest. Nitrite concentrations in rest were the lowest in taekwondo fighters, while rowers had the highest levels among examined groups. The order of magnitude for TBARS level in the rest was bicycling > taekwondo > rowing. During exercise at maximal intensity, the concentration of lactate significantly elevated to similar levels in all tested sportsmen and they were persistently elevated during recovery period of 4 and 10 min. There were no significant changes in O(2) (•-), nitrite, and TBARS levels neither at the maximum intensity of exercise nor during the recovery period comparing to the rest period in examined individuals. Our results showed that long term different training strategies establish different basal nitrites and lipid peroxidation levels in sportmen. However, progressive exercise does not influence basal nitrite and oxidative stress parameters level neither at maximal load nor during the first 10 min of recovery in sportmen studied.

  19. Addition of nitrite enhances the electrochemical defluorination of 2-fluoroaniline

    International Nuclear Information System (INIS)

    Feng, Huajun; Liang, Yuxiang; Guo, Kun; Long, Yuyang; Cong, Yanqing; Shen, Dongsheng

    2015-01-01

    Highlights: • A method for improving defluorination performance by in situ self-assembly of pollutants was developed. • The mechanisms of 2-FA modification and defluorination are discussed. • Positively-charged diazonium salt is used to weaken the C–F bond. - Abstract: This study introduces a novel approach that uses the interaction of pollutants with added nitrite to produce diazonium salts, which cause in situ self-assembly of the pollutants on carbon electrodes, to improve their 2-fluoroaniline (2-FA) defluorination and removal performance. The 2-FA degradation performance, electrode properties, electrochemical properties and degradation pathway were investigated. The reactor containing NO_2"− achieved a 2-FA removal efficiency of 90.1% and a defluorination efficiency of 38% within 48 h, 1.4 and 2.3 times higher than the corresponding results achieved without NO_2"−, respectively. The residual NO_2"− was less than 0.5 mg/L in the reactor containing added NO_2"−, which would not cause serious secondary pollution. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) results proved that the carbon anode surface was successfully modified with benzene polymer, and electrochemical tests confirmed that the electrochemical activity of the modified anode was enhanced significantly. The C–F bond was weakened by the effect of the positive charge of the benzenediazonium groups, and the high electrochemical activity of the carbon anode enhanced the electrochemical performance of the system to accelerate defluorination. Thus, the present electrical method involving nitrite nitrogen is very promising for the treatment of wastewater containing fluoroaniline compounds.

  20. Addition of nitrite enhances the electrochemical defluorination of 2-fluoroaniline

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Huajun [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012 (China); Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012 (China); Laboratory of Microbial Ecology and Technology, Ghent University, Coupure Links 653, B-9000 Ghent (Belgium); Liang, Yuxiang [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012 (China); Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012 (China); Guo, Kun [Laboratory of Microbial Ecology and Technology, Ghent University, Coupure Links 653, B-9000 Ghent (Belgium); Long, Yuyang [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012 (China); Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012 (China); Cong, Yanqing, E-mail: yqcong@hotmail.com [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012 (China); Shen, Dongsheng [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012 (China); Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012 (China)

    2015-12-30

    Highlights: • A method for improving defluorination performance by in situ self-assembly of pollutants was developed. • The mechanisms of 2-FA modification and defluorination are discussed. • Positively-charged diazonium salt is used to weaken the C–F bond. - Abstract: This study introduces a novel approach that uses the interaction of pollutants with added nitrite to produce diazonium salts, which cause in situ self-assembly of the pollutants on carbon electrodes, to improve their 2-fluoroaniline (2-FA) defluorination and removal performance. The 2-FA degradation performance, electrode properties, electrochemical properties and degradation pathway were investigated. The reactor containing NO{sub 2}{sup −} achieved a 2-FA removal efficiency of 90.1% and a defluorination efficiency of 38% within 48 h, 1.4 and 2.3 times higher than the corresponding results achieved without NO{sub 2}{sup −}, respectively. The residual NO{sub 2}{sup −} was less than 0.5 mg/L in the reactor containing added NO{sub 2}{sup −}, which would not cause serious secondary pollution. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) results proved that the carbon anode surface was successfully modified with benzene polymer, and electrochemical tests confirmed that the electrochemical activity of the modified anode was enhanced significantly. The C–F bond was weakened by the effect of the positive charge of the benzenediazonium groups, and the high electrochemical activity of the carbon anode enhanced the electrochemical performance of the system to accelerate defluorination. Thus, the present electrical method involving nitrite nitrogen is very promising for the treatment of wastewater containing fluoroaniline compounds.

  1. Structure of octaheme cytochrome c nitrite reductase from Thioalkalivibrio nitratireducens in a complex with phosphate

    International Nuclear Information System (INIS)

    Trofimov, A. A.; Polyakov, K. M.; Boiko, K. M.; Filimonenkov, A. A.; Dorovatovskii, P. V.; Tikhonova, T. V.; Popov, V. O.; Koval'chuk, M. V.

    2010-01-01

    Octaheme cytochrome c nitrite reductase from Thioalkalivibrio nitratireducens (TvNiR) catalyzes the reduction of nitrite and hydroxylamine to ammonia. The structures of the free enzyme and of the enzyme in complexes with the substrate (nitrite ion) and the inhibitor (azide ion) have been solved previously. In this study we report the structures of the oxidized complex of TvNiR with phosphate and of this complex reduced by europium(II) chloride (1.8- and 2.0-A resolution, the R factors are 15.9 and 16.7%, respectively) and the structure of the enzyme in the complex with cyanide (1.76-A resolution, the R factor is 16.5%), which was prepared by soaking a crystal of the oxidized phosphate complex of TvNiR. In the active site of the enzyme, the phosphate ion binds to the iron ion of the catalytic heme and to the side chains of the catalytic residues Arg131, Tyr303, and His361. The cyanide ion is coordinated to the heme-iron ion and is hydrogen bonded to the residue His361. In the structure of reduced TvNiR, the phosphate ion is bound in the same manner as in the structure of oxidized TvNiR, and the nine c oordinated europium ion is located on the surface of one of the crystallographically independent monomers of the enzyme.

  2. Structure of octaheme cytochrome c nitrite reductase from Thioalkalivibrio nitratireducens in a complex with phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Trofimov, A. A.; Polyakov, K. M., E-mail: kostya@eimb.relarn.ru [Russian Academy of Sciences, Engelhardt Institute of Molecular Biology (Russian Federation); Boiko, K. M.; Filimonenkov, A. A. [Russian Academy of Sciences, Bach Institute of Biochemistry (Russian Federation); Dorovatovskii, P. V. [Kurchatov Center for Synchrotron Radiation and Nanotechnology (Russian Federation); Tikhonova, T. V.; Popov, V. O. [Russian Academy of Sciences, Bach Institute of Biochemistry (Russian Federation); Koval' chuk, M. V. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2010-01-15

    Octaheme cytochrome c nitrite reductase from Thioalkalivibrio nitratireducens (TvNiR) catalyzes the reduction of nitrite and hydroxylamine to ammonia. The structures of the free enzyme and of the enzyme in complexes with the substrate (nitrite ion) and the inhibitor (azide ion) have been solved previously. In this study we report the structures of the oxidized complex of TvNiR with phosphate and of this complex reduced by europium(II) chloride (1.8- and 2.0-A resolution, the R factors are 15.9 and 16.7%, respectively) and the structure of the enzyme in the complex with cyanide (1.76-A resolution, the R factor is 16.5%), which was prepared by soaking a crystal of the oxidized phosphate complex of TvNiR. In the active site of the enzyme, the phosphate ion binds to the iron ion of the catalytic heme and to the side chains of the catalytic residues Arg131, Tyr303, and His361. The cyanide ion is coordinated to the heme-iron ion and is hydrogen bonded to the residue His361. In the structure of reduced TvNiR, the phosphate ion is bound in the same manner as in the structure of oxidized TvNiR, and the nine{sub c}oordinated europium ion is located on the surface of one of the crystallographically independent monomers of the enzyme.

  3. Uncovering the local inelastic interactions during manufacture of ductile cast iron: How the substructure of the graphite particles can induce residual stress concentrations in the matrix

    Science.gov (United States)

    Andriollo, Tito; Hellström, Kristina; Sonne, Mads Rostgaard; Thorborg, Jesper; Tiedje, Niels; Hattel, Jesper

    2018-02-01

    Recent X-ray diffraction (XRD) measurements have revealed that plastic deformation and a residual elastic strain field can be present around the graphite particles in ductile cast iron after manufacturing, probably due to some local mismatch in thermal contraction. However, as only one component of the elastic strain tensor could be obtained from the XRD data, the shape and magnitude of the associated residual stress field have remained unknown. To compensate for this and to provide theoretical insight into this unexplored topic, a combined experimental-numerical approach is presented in this paper. First, a material equivalent to the ductile cast iron matrix is manufactured and subjected to dilatometric and high-temperature tensile tests. Subsequently, a two-scale hierarchical top-down model is devised, calibrated on the basis of the collected data and used to simulate the interaction between the graphite particles and the matrix during manufacturing of the industrial part considered in the XRD study. The model indicates that, besides the viscoplastic deformation of the matrix, the effect of the inelastic deformation of the graphite has to be considered to explain the magnitude of the XRD strain. Moreover, the model shows that the large elastic strain perturbations recorded with XRD close to the graphite-matrix interface are not artifacts due to e.g. sharp gradients in chemical composition, but correspond to residual stress concentrations induced by the conical sectors forming the internal structure of the graphite particles. In contrast to common belief, these results thus suggest that ductile cast iron parts cannot be considered, in general, as stress-free at the microstructural scale.

  4. Dietary polyphenols generate nitric oxide from nitrite in the stomach and induce smooth muscle relaxation

    International Nuclear Information System (INIS)

    Rocha, Barbara S.; Gago, Bruno; Barbosa, Rui M.; Laranjinha, Joao

    2009-01-01

    Nitrite, considered a biological waste and toxic product, is being regarded as an important physiological molecule in nitric oxide (·NO) biochemistry. Because the interaction of dietary phenolic compounds and nitrite would be kinetically (due to the high concentrations achieved) and thermodynamically (on basis of the redox potentials) feasible in the stomach, we have studied the potential reduction of nitrite by polyphenols present in several dietary sources. By measuring the time courses of ·NO production in simulated gastric juice (pH 2), the efficiency of the compounds studied is as follows: Epicatechin-3-O-gallate > quercetin > procyanidin B8 dimer > oleuropein > procyanidin B2 dimer > chlorogenic acid > epicatechin > catechin > procyanidin B5 dimer. The initial rates of ·NO production fall in a narrow range (ca. 1-5 μM s -1 ) but the distinct kinetics of the decay of ·NO signals suggest that competition reactions for ·NO are operative. The proof of concept that, in the presence of nitrite, phenol-containing dietary products induce a strong increase of ·NO in the stomach was established in an in vivo experiment with healthy volunteers consuming lettuce, onions, apples, wine, tea, berries and cherries. Moreover, selected mixtures of oleuropein and catechin with low nitrite (1 μM) were shown to induce muscle relaxation of stomach strips in a structure-dependent way. Data presented here brings strong support to the concept that polyphenols consumed in a variety of dietary products, under gastric conditions, reduce nitrite to ·NO that, in turn, may exert a biological impact as a local relaxant.

  5. Safer and healthier reduced nitrites turkey meat sausages using lyophilized Cystoseira barbata seaweed extract.

    Science.gov (United States)

    Sellimi, Sabrine; Benslima, Abdelkarim; Ksouda, Ghada; Montero, Veronique Barragan; Hajji, Mohamed; Nasri, Moncef

    2017-10-21

    Background Nitrite salts are still common additives in the meat industry. The present study provides a first approach on the employment of the lyophilized aqueous extract (WE) of the Tunisian seaweed Cystoseira barbata for the quality enhancement of turkey meat sausage. Methods WE was supplemented as a natural antioxidant agent to investigate its effectiveness in delaying lipid oxidation turkey meat sausages containing reduced amounts of sodium nitrites. Results On storage day 5, all concentrations of WE (0.01-0.4 %) reduced the meat lipid oxidation by approximately 36 %, as compared to the negative control containing only 80 mg/kg of meat of sodium nitrites as antioxidant. It was noted that within 15 days of refrigerated storage, a meat system containing 80 mg/kg of meat of sodium nitrites and 0.02 % and 0.04 % of WE had similar Thiobarbituric Acid Reactive Substances (TBARS) levels (19±1.32 and 17±1.12 µmol/kg of meat, respectively), which were comparable to the positive control containing sodium nitrites (150 mg/kg of meat) and 0.045 % vitamin C (18.46±1.27 µmol/kg of meat). In-depth, the metabolomic profiling using gas chromatography-mass spectrometry (GC/MS) and liquid chromatography-quadripole-time-of-flight-mass spectrometry (LC-QTOF-MS) analyses of the Tunisian seaweed C. barbata solvent extracts showed that the main active compounds were phenolic compounds, fatty acids and sterols. Conclusions Overall, the cold medium containing C. barbata lyophilized aqueous extrac, with strong antioxidant activity and antihypertensive properties, may open the way to the development of a natural quality enhancement strategy for new functional and ever healthier reduced nitrites meat sausages based on algae.

  6. Influence of Polysaccharide Krestin from Coriolus versicolor Extract on Nitrite and Malondialdehyde Concencentrations of Mus musculus Serum Exposed by Mycobacterium tuberculosis

    Directory of Open Access Journals (Sweden)

    Sri Puji Astuti Wahyuningsih

    2016-03-01

    Full Text Available Mycobacterium tuberculosis is a major infection agent of tuberculosis that is controlled by the response of cell-mediated immunity. It is macrophages and cytolytic T lymphocytes. Activated macrophages will produce free radicals. Excessive free radicals cause tissue damage. Polysaccharide krestin contains β-glucan. It is a scavenger of free radicals. This research aimed to identify the influence of polysaccharide krestin from C. versicolor on nitrite and malondialdehyde concentrations of mice serum exposed by M. tuberculosis. Nitrite concentration was determined by nitrite assay. Malondialdehyde concentration was determined by TBARS assay. The result showed that adding polysaccharide krestin before exposure (P1 and adding polysaccharide krestin before-after exposure (P3 had the best potential to decrease nitrite concentration. Nitrite concentrations of P1 and P3 were 1.364 ± 0.523 M and 1.456 ± 0.712 M respectively. Meanwhile, P1 group and adding polysaccharide krestin after exposure (P2 had the best potential to decrease malondialdehyde concentration. Malondialdehyde concentrations of P1 and P2 were 1125.86 ± 97.96 µM and 953.86 ± 328.16 µM respectively. Their nitrite and malondialdehyde concentrations decreased, compared to K and K- groups. The research conclusion was that adding polysaccharide krestin before exposure could decrease both nitrite and malondialdehyde concentrations.How to CiteWahyuningsih, S., Pramudya, M., & Sugiharto, S. (2016. Influence of Polysaccharide Krestin from Coriolus versicolor Extract on Nitrite and Malondialdehyde Concencentrations of Mus musculus Serum Exposed by Mycobacterium tuberculosis. Biosaintifika: Journal of Biology & Biology Education, 8(1, 12-17.

  7. Using ultra-osmosis to concentrate residues upto 20% solids using 10% of the energy of conventional methods

    Energy Technology Data Exchange (ETDEWEB)

    O' Shea, J A

    1990-01-01

    In the Food Industry, generally that is, Milk, Beet, Grain and Potato processing the major energy input is the removal of water from the raw material. This is particularly important in the milk Industry where liquid milk has a water content of 88%. When the fat and protein are removed it is only 6% solid or 94% water. The consideration of Ultra-Osmosis is beneficial in its energy efficiency compared to thermal vapour recompression and also has the side benefit as being a demineralisation plant as well. Reverse Osmosis is a unique cross lined polyamide membrane. Its rejection characteristics enable it to discriminate among low molecular weight species. The pore structure of the membrane is such that a separation between sodium chloride and calcium sulphate may be accomplished. Such separations are useful in a variety of applications. The utility of the membrane is further enhanced by the simultaneous ability to concentrate the retained species. The Ultra Osmosis process based on a membrane with rejection characteristics intermediate between those common in Ultra Filtration and Reverse Osmosis opens the road to a whole new spectrum of membrane separations. 3 figs.

  8. Enhanced primary treatment of concentrated black water and kitchen residues within DESAR concept using two types of anaerobic digesters.

    Science.gov (United States)

    Kujawa-Roeleveld, K; Elmitwalli, T; Zeeman, G

    2006-01-01

    Anaerobic digestion of concentrated domestic wastewater streams--black or brown water, and solid fraction of kitchen waste is considered as a core technology in a source separation based sanitation concept (DESAR--decentralised sanitation and reuse). A simple anaerobic digester can be implemented for an enhanced primary treatment or, in some situations, as a main treatment. Two reactor configurations were extensively studied; accumulation system (AC) and UASB septic tank at 15, 20 and 25 degrees C. Due to long retention times in an AC reactor, far stabilisation of treated medium can be accomplished with methanisation up to 60%. The AC systems are the most suitable to apply when the volume of waste to be treated is minimal and when a direct reuse of a treated medium in agriculture is possible. Digested effluent contains both liquid and solids. In a UASB septic tank, efficient separation of solids and liquid is accomplished. The total COD removal was above 80% at 25 degrees C. The effluent contains COD and nutrients, mainly in a soluble form. The frequency of excess sludge removal is low and sludge is well stabilised due to a long accumulation time.

  9. Behaviors of nitrite in cured meat

    International Nuclear Information System (INIS)

    Miwa, Misao

    1980-01-01

    The behaviors of nitrite in cured meat were studied by means of 15 N on the basis of the gaseous 15 N volume from the added nitric acid. The myoglobin, 15 N-nitrite and ascorbate model systems showed a 15 N recovery rate of approximately 100%, but actual meat samples, treated similarly, showed a recovery rate ranging from 66 to 90%, with formation of an unidentified 15 N agent. The largest amount of this unidentified agent was obtained by reaction of the 0.05 M NaCl-soluble dialyzable fraction of meat with 15 N-nitrite. When the reaction product was isolated by Sephadex column chromatography, 15 N in the fraction, which was thought to be the agent, contained approximately 26% of the added 15 N, possessed no UV absorption, and was negative for a ninhydrin reagent. Of the NaCl soluble fraction, reaction in the acidic fraction produced the largest quantity of the unidentified 15 N compound (31% of the added 15 N). This compound was strongly acidic and consisted of 30.7% C, 6.6% H and 4.9% N on element analysis. It showed no mutagenicity against Salmonella by Ames Test. (Chiba, N.)

  10. Optimization of elution salt concentration in stepwise elution of protein chromatography using linear gradient elution data. Reducing residual protein A by cation-exchange chromatography in monoclonal antibody purification.

    Science.gov (United States)

    Ishihara, Takashi; Kadoya, Toshihiko; Endo, Naomi; Yamamoto, Shuichi

    2006-05-05

    Our simple method for optimization of the elution salt concentration in stepwise elution was applied to the actual protein separation system, which involves several difficulties such as detection of the target. As a model separation system, reducing residual protein A by cation-exchange chromatography in human monoclonal antibody (hMab) purification was chosen. We carried out linear gradient elution experiments and obtained the data for the peak salt concentration of hMab and residual protein A, respectively. An enzyme-linked immunosorbent assay was applied to the measurement of the residual protein A. From these data, we calculated the distribution coefficient of the hMab and the residual protein A as a function of salt concentration. The optimal salt concentration of stepwise elution to reduce the residual protein A from the hMab was determined based on the relationship between the distribution coefficient and the salt concentration. Using the optimized condition, we successfully performed the separation, resulting in high recovery of hMab and the elimination of residual protein A.

  11. Nitrite in feed: From Animal health to human health

    Energy Technology Data Exchange (ETDEWEB)

    Cockburn, Andrew [Institute for Research on Environment and Sustainability, Devonshire Building, University of Newcastle upon Tyne, Newcastle upon Tyne, NE17RU (United Kingdom); Brambilla, Gianfranco [Istituto Superiore di Sanità, Toxicological chemistry unit, Viale Regina Elena 299, 00161 Rome (Italy); Fernández, Maria-Luisa [Departamento de Medio Ambiente, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Ministerio de Ciencia e Innovación, Carretera de la Coruña, 28040 Madrid (Spain); Arcella, Davide [Unit on Data Collection and Exposure, European Food Safety Authority, Largo N. Palli 5/A43100 Parma (Italy); Bordajandi, Luisa R. [Unit on Contaminants in the Food chain, European Food Safety Authority, Largo N. Palli 5/A, 43100 Parma (Italy); Cottrill, Bruce [Policy Delivery Group, Animal Health and Welfare, ADAS, Wolverhampton (United Kingdom); Peteghem, Carlos van [University of Gent, Harelbekestraat 72, 9000 Gent (Belgium); Dorne, Jean-Lou, E-mail: jean-lou.dorne@efsa.europa.eu [Unit on Contaminants in the Food chain, European Food Safety Authority, Largo N. Palli 5/A, 43100 Parma (Italy)

    2013-08-01

    Nitrite is widely consumed from the diet by animals and humans. However the largest contribution to exposure results from the in vivo conversion of exogenously derived nitrate to nitrite. Because of its potential to cause to methaemoglobin (MetHb) formation at excessive levels of intake, nitrite is regulated in feed and water as an undesirable substance. Forages and contaminated water have been shown to contain high levels of nitrate and represent the largest contributor to nitrite exposure for food-producing animals. Interspecies differences in sensitivity to nitrite intoxication principally result from physiological and anatomical differences in nitrite handling. In the case of livestock both pigs and cattle are relatively susceptible. With pigs this is due to a combination of low levels of bacterial nitrite reductase and hence potential to reduce nitrite to ammonia as well as reduced capacity to detoxify MetHb back to haemoglobin (Hb) due to intrinsically low levels of MetHb reductase. In cattle the sensitivity is due to the potential for high dietary intake and high levels of rumen conversion of nitrate to nitrite, and an adaptable gut flora which at normal loadings shunts nitrite to ammonia for biosynthesis. However when this escape mechanism gets overloaded, nitrite builds up and can enter the blood stream resulting in methemoglobinemia. Looking at livestock case histories reported in the literature no-observed-effect levels of 3.3 mg/kg body weight (b.w.) per day for nitrite in pigs and cattle were estimated and related to the total daily nitrite intake that would result from complete feed at the EU maximum permissible level. This resulted in margins of safety of 9-fold and 5-fold for pigs and cattle, respectively. Recognising that the bulkiness of animal feed limits their consumption, these margins in conjunction with good agricultural practise were considered satisfactory for the protection of livestock health. A human health risk assessment was also

  12. Nitrite in feed: From Animal health to human health

    International Nuclear Information System (INIS)

    Cockburn, Andrew; Brambilla, Gianfranco; Fernández, Maria-Luisa; Arcella, Davide; Bordajandi, Luisa R.; Cottrill, Bruce; Peteghem, Carlos van; Dorne, Jean-Lou

    2013-01-01

    Nitrite is widely consumed from the diet by animals and humans. However the largest contribution to exposure results from the in vivo conversion of exogenously derived nitrate to nitrite. Because of its potential to cause to methaemoglobin (MetHb) formation at excessive levels of intake, nitrite is regulated in feed and water as an undesirable substance. Forages and contaminated water have been shown to contain high levels of nitrate and represent the largest contributor to nitrite exposure for food-producing animals. Interspecies differences in sensitivity to nitrite intoxication principally result from physiological and anatomical differences in nitrite handling. In the case of livestock both pigs and cattle are relatively susceptible. With pigs this is due to a combination of low levels of bacterial nitrite reductase and hence potential to reduce nitrite to ammonia as well as reduced capacity to detoxify MetHb back to haemoglobin (Hb) due to intrinsically low levels of MetHb reductase. In cattle the sensitivity is due to the potential for high dietary intake and high levels of rumen conversion of nitrate to nitrite, and an adaptable gut flora which at normal loadings shunts nitrite to ammonia for biosynthesis. However when this escape mechanism gets overloaded, nitrite builds up and can enter the blood stream resulting in methemoglobinemia. Looking at livestock case histories reported in the literature no-observed-effect levels of 3.3 mg/kg body weight (b.w.) per day for nitrite in pigs and cattle were estimated and related to the total daily nitrite intake that would result from complete feed at the EU maximum permissible level. This resulted in margins of safety of 9-fold and 5-fold for pigs and cattle, respectively. Recognising that the bulkiness of animal feed limits their consumption, these margins in conjunction with good agricultural practise were considered satisfactory for the protection of livestock health. A human health risk assessment was also

  13. The role of bicarbonate in platelet additive solution for apheresis platelet concentrates stored with low residual plasma.

    Science.gov (United States)

    Radwanski, Katherine; Min, Kyungyoon

    2013-03-01

    Complex platelet additive solutions (PASs) are required to store platelet (PLT) concentrates with plasma levels below 30%. Previously, apheresis PLTs stored with 5% plasma in acetate- and bicarbonate-containing PAS maintained stable pH and bicarbonate levels during 7-day storage. Due to this observation, the necessity of added bicarbonate in PAS was investigated and whether the concurrent increase in PAS pH after bicarbonate addition had any effect on PLT storage. Apheresis PLTs were stored in 5% plasma-95% high- or low-pH PAS, with or without bicarbonate (n=10 per arm). Bicarbonate PAS PLTs were paired and nonbicarbonate PAS PLTs were paired (split from same double-dose collection). PLTs were evaluated for in vitro variables on Days 1 and 7 and up to Day 14 if the Day 7 pH was higher than 6.2. PLT pH was maintained above 7.3 to Day 14 in bicarbonate PAS PLTs while pH failures below 6.2 were observed in 4 of 10 and 2 of 10 units on Day 7 in low- and high-pH nonbicarbonate PAS arms, respectively. Day 7 in vitro variables in nonbicarbonate PAS PLTs with pH values of higher than 6.2 were comparable to Day 7 variables in bicarbonate PAS PLTs. The pH of bicarbonate PAS did have a small effect on pH and bicarbonate levels in PLT units, but did not have an effect on functional variables and metabolism. Bicarbonate was not required to maintain in vitro PLT function in 5% plasma-95% PAS, but was required as a pH buffer and increased PAS pH did not significantly contribute to this effect. © 2012 American Association of Blood Banks.

  14. The role of red blood cell S-nitrosation in nitrite bioactivation and its modulation by leucine and glucose

    Directory of Open Access Journals (Sweden)

    Nadeem Wajih

    2016-08-01

    Full Text Available Previous work has shown that red blood cells (RBCs reduce nitrite to NO under conditions of low oxygen. Strong support for the ability of red blood cells to promote nitrite bioactivation comes from using platelet activation as a NO-sensitive process. Whereas addition of nitrite to platelet rich plasma in the absence of RBCs has no effect on inhibition of platelet activation, when RBCs are present platelet activation is inhibited by an NO-dependent mechanism that is potentiated under hypoxia. In this paper, we demonstrate that nitrite bioactivation by RBCs is blunted by physiologically-relevant concentrations of nutrients including glucose and the important signaling amino acid leucine. Our mechanistic investigations demonstrate that RBC mediated nitrite bioactivation is largely dependent on nitrosation of RBC surface proteins. These data suggest a new expanded paradigm where RBC mediated nitrite bioactivation not only directs blood flow to areas of low oxygen but also to areas of low nutrients. Our findings could have profound implications for normal physiology as well as pathophysiology in a variety of diseases including diabetes, sickle cell disease, and arteriosclerosis.

  15. Mechanism of pitting corrosion prevention by nitrite in carbon steel exposed to dilute salt solutions. 1998 annual progress report

    International Nuclear Information System (INIS)

    Zapp, P.E.; Zee, J. van.

    1998-01-01

    'The overall goal of this project is to develop a fundamental understanding of the role of nitrite in preventing the breakdown of protective oxide(s) on carbon steel and the onset of pitting. Pitting corrosion of carbon steel exposed to dilute alkaline salt solutions can be induced by nitrate, sulfate, and chloride ions and is prevented by sufficient concentration of nitrite. A significant example of this material/electrolyte system is the storage and processing of DOE''s high-level radioactive liquid waste in carbon steel tanks. Added nitrite in the waste has a considerable downstream impact on the immobilization of the waste in a stable glass form. Waste tank integrity and glass production efficiency may benefit from the fundamental understanding of nitrite''s role in preventing pitting. This report summarizes progress after approximately six months of effort in this three-year EMSP project. Initial experimental and theoretical work has focused on the electrochemical behavior of carbon steel in simplified non-radioactive solutions that simulate complex dilute radioactive waste solutions. These solutions contain corrosion-inducing species such as nitrate and chloride and the corrosion-inhibiting nitrite at moderately alkaline pHs. The electrochemical behavior of interest here is that of the open-circuit potential of the steel specimen at equilibrium in the experimental electrolyte and the measures of the steel''s passivity and passivity breakdown.'

  16. Synthesis, characterization and nitrite ion sensing performance of reclaimable composite samples through a core-shell structure

    Science.gov (United States)

    Cui, Xiao; Yuqing, Zhao; Cui, Jiantao; Zheng, Qian; Bo, Wang

    2018-02-01

    The following paper reported and discussed a nitrite ion optical sensing platform based on a core-shell structure, using superamagnetic nanoparticles as the core, a silica molecular sieve MCM-41 as the shell and two rhodamine derivatives as probe, respectively. This superamagnetic core made this sensing platform reclaimable after finishing nitrite ion sensing procedure. This sensing platform was carefully characterized by means of electron microscopy images, porous structure analysis, magnetic response, IR spectra and thermal stability analysis. Detailed analysis suggested that the emission of these composite samples was quenchable by nitrite ion, showing emission turn off effect. A static sensing mechanism based on an additive reaction between chemosensors and nitrite ion was proposed. These composite samples followed Demas quenching equation against different nitrite ion concentrations. Limit of detection value was obtained as low as 0.4 μM. It was found that, after being quenched by nitrite ion, these composite samples could be reclaimed and recovered by sulphamic acid, confirming their recyclability.

  17. Fine structure characterization of zero-valent iron nanoparticles for decontamination of nitrites and nitrates in wastewater and groundwater

    Directory of Open Access Journals (Sweden)

    Kuen-Song Lin et al

    2008-01-01

    Full Text Available The main objectives of the present study were to investigate the chemical reduction of nitrate or nitrite species by zero-valent iron nanoparticle (ZVIN in aqueous solution and related reaction kinetics or mechanisms using fine structure characterization. This work also exemplifies the utilization of field emission-scanning electron microscope (FE–SEM, transmission electron microscopy (TEM, and x-ray diffraction (XRD to reveal the speciation and possible reaction pathway in a very complex adsorption and redox reaction process. Experimentally, ZVIN of this study was prepared by sodium borohydride reduction method at room temperature and ambient pressure. The morphology of as-synthesized ZVIN shows that the nearly ball and ultrafine particles ranged of 20–50 nm were observed with FE–SEM or TEM analysis. The kinetic model of nitrites or nitrates reductive reaction by ZVIN is proposed as a pseudo first-order kinetic equation. The nitrite and nitrate removal efficiencies using ZVIN were found 65–83% and 51–68%, respectively, based on three different initial concentrations. Based on the XRD pattern analyses, it is found that the quantitative relationship between nitrite and Fe(III or Fe(II is similar to the one between nitrate and Fe(III in the ZVIN study. The possible reason is due to the faster nitrite reduction by ZVIN. In fact, the occurrence of the relative faster nitrite reductive reaction suggested that the passivation of the ZVIN have a significant contribution to iron corrosion. The extended x-ray absorption fine structure (EXAFS or x-ray absorption near edge structure (XANES spectra show that the nitrites or nitrates reduce to N2 or NH3 while oxidizing the ZVIN to Fe2O3 or Fe3O4 electrochemically. It is also very clear that decontamination of nitrate or nitrite species in groundwater via the in-situ remediation with a ZVIN permeable reactive barrier would be environmentally attractive.

  18. Inhibition of toxigenesis of group II (nonproteolytic) Clostridium botulinum type B in meat products by using a reduced level of nitrite.

    Science.gov (United States)

    Keto-Timonen, Riikka; Lindström, Miia; Puolanne, Eero; Niemistö, Markku; Korkeala, Hannu

    2012-07-01

    The effect of three different concentrations of sodium nitrite (0, 75, and 120 mg/kg) on growth and toxigenesis of group II (nonproteolytic) Clostridium botulinum type B was studied in Finnish wiener-type sausage, bologna-type sausage, and cooked ham. A low level of inoculum (2.0 log CFU/g) was used for wiener-type sausage and bologna-type sausage, and both low (2.0 log CFU/g) and high (4.0 log CFU/g) levels were used for cooked ham. The products were formulated and processed under simulated commercial conditions and stored at 8°C for 5 weeks. C. botulinum counts were determined in five replicate samples of each nitrite concentration at 1, 3, and 5 weeks after thermal processing. All samples were positive for C. botulinum type B. The highest C. botulinum counts were detected in nitrite-free products. Toxigenesis was observed in nitrite-free products during storage, but products containing either 75 or 120 mg/kg nitrite remained nontoxic during the 5-week study period, suggesting that spores surviving the heat treatment were unable to germinate and develop into a toxic culture in the presence of nitrite. The results suggest that the safety of processed meat products with respect to group II C. botulinum type B can be maintained even with a reduced concentration (75 mg/kg) of sodium nitrite.

  19. Isolation of nitrite-degrading strains from Douchi and their application to degrade high nitrite in Jiangshui.

    Science.gov (United States)

    Guo, Xing; Liu, Bianfang; Gao, Lina; Zhou, Yuan; Shan, Yuanyuan; Lü, Xin

    2018-06-01

    Excessive nitrite in food is potentially harmful to human health because of its carcinogenic effects caused by nitroso-dervivatives. Douchi, which widely distributed throughout the country, is a traditional solid fermented soybean food with low nitrite content. In this study, bacterias which can degrade nitrite were isolated from Douchi and identified according to 16S rDNA sequence. Acinetobacter guillouiae, Acinetobacter bereziniae, Bacillus subtilis, Bacillus tequilensis, Bacillus amyloliquefaciens, Bacillus licheniformis, Bacillus aryabhattai and Bacillus methylotrophicus were selected. It was shown that all strains have nitrite degradation capability, in which 99.41 % nitrite can be degraded by Bacillus subtilis NDS1. The enzyme activities of these strains were determined at 24 h and 48 h, which corresponded to their nitrite degradation rates. The strains were firstly tried to inoculate in Jiangshui, which is a kind of traditional fermented vegetable in northwest China and often has high nitrite content. It was found that Bacillus subtilis NDS1, Bacillus tequilensis NDS3, Acinetobacter bereziniae NDS4, Bacillus subtilis NDS6, Bacillus subtilis NDS12 can degrade nitrite in Jiangshui more quickly, among which Acinetobacter bereziniae NDS4 degraded almost all nitrite in 48 h while it took 180 h for control. These results indicated that the selected strains have potential to become nitrite degradition agent in food. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  20. Effects of waterborne nitrite on hematological parameters and stress indicators in olive flounders, Paralichthys olivaceus, raised in bio-floc and seawater.

    Science.gov (United States)

    Kim, Jun-Hwan; Kim, Jin-Young; Lim, Lok-Ji; Kim, Su Kyoung; Choi, Hye Sung; Hur, Young Baek

    2018-06-11

    Juvenile olive flounders, Paralichthys olivaceus (mean weight 2.69 ± 0.31 g), were raised in bio-floc and seawater for six months, these P. olivaceus (mean weight 280.1 ± 10.5 g, mean length 28.37 ± 2.3 cm) were exposed to different concentrations of waterborne nitrite (0, 25, 50, 100, and 200 mg NO 2 - /L) for 7 days. None of the P. olivaceus individuals exposed to bio-floc and seawater containing waterborne nitrite concentrations of 200 mg/L for 7 days survived. Hematological parameters (hemoglobin and hematocrit) were significantly reduced by nitrite exposure. Regarding plasma components, the concentrations of glucose, glutamic oxalate transaminase (GOT), and glutamic pyruvate transaminase (GPT) increased significantly in response to nitrite exposure, whereas cholesterol concentrations significantly decreased. Stress indicators, including concentrations of plasma glucose, cortisol, and liver and gill concentrations of heat shock protein 70 (HSP70) were significantly increased by nitrite exposure. The results of the study indicate that nitrite exposure affected the hematological parameters and stress indicators of P. olivaceus raised in bio-floc and seawater, and these changes were more prominent in the P. olivaceus raised in seawater than those raised in bio-floc. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. Nitrate and nitrite in biology, nutrition and therapeutics

    Science.gov (United States)

    Lundberg, Jon O.; Gladwin, Mark T.; Ahluwalia, Amrita; Benjamin, Nigel; Bryan, Nathan S.; Butler, Anthony; Cabrales, Pedro; Fago, Angela; Feelisch, Martin; Ford, Peter C.; Freeman, Bruce A.; Frenneau, Michael; Friedman, Joel; Kelm, Malte; Kevil, Christopher G.; Kim-Shapiro, Daniel B.; Kozlov, Andrey V.; Lancaster, Jack R.; Lefer, David J.; McColl, Kenneth; McCurry, Kenneth; Patel, Rakesh; Petersson, Joel; Rassaf, Tienush; Reutov, Valentin P.; Richter-Addo, George B.; Schechter, Alan; Shiva, Sruti; Tsuchiya, Koichiro; van Faassen, Ernst E.; Webb, Andrew J.; Zuckerbraun, Brian S.; Zweier, Jay L.; Weitzberg, Eddie

    2014-01-01

    Inorganic nitrate and nitrite from endogenous or dietary sources are metabolized in vivo to nitric oxide (NO) and other bioactive nitrogen oxides. The nitrate-nitrite-NO pathway is emerging as an important mediator of blood flow regulation, cell signaling, energetics and tissue responses to hypoxia. The latest advances in our understanding of the biochemistry, physiology and therapeutics of nitrate, nitrite and NO were discussed during a recent two-day meeting at the Nobel Forum, Karolinska Institutet in Stockholm. PMID:19915529

  2. Methaemoglobinaemia due to amyl nitrite inhalation: a case report.

    Science.gov (United States)

    Machabert, R; Testud, F; Descotes, J

    1994-05-01

    Methaemoglobinaemia is a potential toxic effect of aliphatic nitrites which are increasingly abused by male homosexuals and drug addicts because of marked vasodilating properties ('poppers'). In most instances, severe complications were described following the ingestion of large quantities of amyl, butyl or isobutyl nitrites. A deficiency in NADH-dependent haemoglobin reductase in some patients has been noted. This is the first report of symptomatic methaemoglobinaemia following the inhalation of amyl nitrite.

  3. The role of nitrite in nitric oxide homeostasis

    DEFF Research Database (Denmark)

    Jensen, Frank Bo

    2009-01-01

    Nitrite is endogenously produced as an oxidative metabolite of nitric oxide, but it also functions as a NO donor that can be activated by a number of cellular proteins under hypoxic conditions. This article discusses the physiological role of nitrite and nitrite-derived NO in blood flow regulation...... mechanisms. Nitrite reduction to NO provides cytoprotection in tissues during ischemia-reperfusion events by inhibiting mitochondrial respiration and limiting reactive oxygen species. It is argued that the study of hypoxia-tolerant lower vertebrates and diving mammals may help evaluate mechanisms and a full...

  4. Nitrite promotes protein carbonylation and Strecker aldehyde formation in experimental fermented sausages: are both events connected?

    Science.gov (United States)

    Villaverde, A; Ventanas, J; Estévez, M

    2014-12-01

    The role played by curing agents (nitrite, ascorbate) on protein oxidation and Strecker aldehyde formation is studied. To fulfill this objective, increasing concentrations of nitrite (0, 75 and 150ppm) and ascorbate (0, 250 and 500ppm) were added to sausages subjected to a 54day drying process. The concurrence of intense proteolysis, protein carbonylation and formation of Strecker aldehydes during processing of sausages suggests that α-aminoadipic semialdehyde (AAS) and γ-glutamic semialdehyde (GGS) may be implicated in the formation of Strecker aldehydes. The fact that nitrite (150ppm, ingoing amount) significantly promoted the formation of protein carbonyls at early stages of processing and the subsequent formation of Strecker aldehydes provides strength to this hypothesis. Ascorbate (125 and 250ppm) controlled the overall extent of protein carbonylation in sausages without declining the formation of Strecker aldehydes. These results may contribute to understanding the chemistry fundamentals of the positive influence of nitrite on the flavor and overall acceptability of cured muscle foods. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Determination of Nitrite and Nitrate in Natural Waters Using Flow Injection with Spectrophotometric Detection

    International Nuclear Information System (INIS)

    Yaqoob, M.; Nabi, A.

    2013-01-01

    A simple and sensitive flow injection spectrophotometric method is reported for the room temperature determination of nitrite and nitrate based on the Griess reaction and a copperised cadmium column for reduction of nitrate. Calibration graphs were linear over the range 2 - 1000 micro g N L /sup -1/ (R2 = 0.9997 and 0.9999, n = 9) with a limit of detection (3 s.d.) of 1.0 micro g N L and relative standard deviations (n = 10) of 0.9 and 1.2% for 50 micro g N L nitrite and nitrate respectively. The sample throughput was 50 h. The effect of reagent concentrations, physical parameters (flow rate, sample volume, reaction coil and copperised cadmium column length) and the potential interferences are reported. The effect of salinity on the blank and on the determination of nitrite and nitrate are also presented. The method was applied to natural waters (rainwater, freshwater and estuarine water) and the results for nitrite + nitrate (140 - 7310 micro g N L/sup -1/) were not significantly different (95% confidence interval) from results obtained using a segmented flow analyser reference method with spectrophotometric detection. (author)

  6. Accounting for Genotype-by-Environment Interactions and Residual Genetic Variation in Genomic Selection for Water-Soluble Carbohydrate Concentration in Wheat.

    Science.gov (United States)

    Ovenden, Ben; Milgate, Andrew; Wade, Len J; Rebetzke, Greg J; Holland, James B

    2018-05-31

    Abiotic stress tolerance traits are often complex and recalcitrant targets for conventional breeding improvement in many crop species. This study evaluated the potential of genomic selection to predict water-soluble carbohydrate concentration (WSCC), an important drought tolerance trait, in wheat under field conditions. A panel of 358 varieties and breeding lines constrained for maturity was evaluated under rainfed and irrigated treatments across two locations and two years. Whole-genome marker profiles and factor analytic mixed models were used to generate genomic estimated breeding values (GEBVs) for specific environments and environment groups. Additive genetic variance was smaller than residual genetic variance for WSCC, such that genotypic values were dominated by residual genetic effects rather than additive breeding values. As a result, GEBVs were not accurate predictors of genotypic values of the extant lines, but GEBVs should be reliable selection criteria to choose parents for intermating to produce new populations. The accuracy of GEBVs for untested lines was sufficient to increase predicted genetic gain from genomic selection per unit time compared to phenotypic selection if the breeding cycle is reduced by half by the use of GEBVs in off-season generations. Further, genomic prediction accuracy depended on having phenotypic data from environments with strong correlations with target production environments to build prediction models. By combining high-density marker genotypes, stress-managed field evaluations, and mixed models that model simultaneously covariances among genotypes and covariances of complex trait performance between pairs of environments, we were able to train models with good accuracy to facilitate genetic gain from genomic selection. Copyright © 2018 Ovenden et al.

  7. Unimolecular Reactions of Nitrites and Nitrates.

    Science.gov (United States)

    1983-04-01

    verified the mechanism as being the one originally proposed by Levy, RONO - RO + NO RO + NO- 1 2*RONO •I kRO + NO-- ROH HHO -Hi k5 :and not by direct...produced by ,’Levy’s mechanism. I1 Emission from CH30, C2H50, and l-C3H70 radicals were observed in the photolysis of these nitrites between...wavelengths of 2000 and 1100 A, by Ohbayashi, Akimoto and Tanaka [78]. Emission was assigned to the (A2A1IX2E) transition of CH30 . Bands of NO were also *i

  8. Comparison of Oxidation Kinetics of Nitrite-Oxidizing Bacteria: Nitrite Availability as a Key Factor in Niche Differentiation

    Science.gov (United States)

    Nowka, Boris; Daims, Holger

    2014-01-01

    Nitrification has an immense impact on nitrogen cycling in natural ecosystems and in wastewater treatment plants. Mathematical models function as tools to capture the complexity of these biological systems, but kinetic parameters especially of nitrite-oxidizing bacteria (NOB) are lacking because of a limited number of pure cultures until recently. In this study, we compared the nitrite oxidation kinetics of six pure cultures and one enrichment culture representing three genera of NOB (Nitrobacter, Nitrospira, Nitrotoga). With half-saturation constants (Km) between 9 and 27 μM nitrite, Nitrospira bacteria are adapted to live under significant substrate limitation. Nitrobacter showed a wide range of lower substrate affinities, with Km values between 49 and 544 μM nitrite. However, the advantage of Nitrobacter emerged under excess nitrite supply, sustaining high maximum specific activities (Vmax) of 64 to 164 μmol nitrite/mg protein/h, contrary to the lower activities of Nitrospira of 18 to 48 μmol nitrite/mg protein/h. The Vmax (26 μmol nitrite/mg protein/h) and Km (58 μM nitrite) of “Candidatus Nitrotoga arctica” measured at a low temperature of 17°C suggest that Nitrotoga can advantageously compete with other NOB, especially in cold habitats. The kinetic parameters determined represent improved basis values for nitrifying models and will support predictions of community structure and nitrification rates in natural and engineered ecosystems. PMID:25398863

  9. Effect of the kinetics of ammonium and nitrite oxidation on nitritation success or failure for different biofilm reactor geometries

    DEFF Research Database (Denmark)

    Lackner, Susanne; Smets, Barth F.

    2012-01-01

    was on the influence of key biokinetic parameters (maximum specific growth rates, oxygen and nitrogen affinity constants of AOB (ammonium oxidizing bacteria) and NOB (nitrite oxidizing bacteria)) and their ratios on nitritation efficiency in these geometries. This exhaustive simulation study revealed that nitritation...... strongly depends on the chosen kinetic parameters of AOB and NOB. The maximum specific growth rates (μmax,AOB and μmax,NOB) had the strongest impact on nitritation efficiency (NE). In comparison, the counter-diffusion geometry yielded more parameter combinations (27.5%) that resulted in high NE than the co...

  10. Enhancement of nitrite on heme-induced oxidative reactions: A potential toxicological implication.

    Science.gov (United States)

    Lu, Naihao; Chen, Wei; Zhu, Jingjie; Peng, Yi-Yuan

    2012-02-01

    Evidence to support the role of heme as major inducers of oxidative damage is increasingly present. Nitrite (NO(2)(-)) is one of the major end products of NO metabolism. Although the biological significance of heme/NO(2)(-)-mediated protein tyrosine nitration is a subject of great interest, the important roles of NO(2)(-) on heme-dependent redox reaction have been greatly underestimated. In this study, we investigated the influence of NO(2)(-) on heme -dependent oxidative reactions. It was found that NO(2)(-) had the capacity to act as a reducing agent to remove high oxidation states of heme iron. In the reduction of ferryl heme to ferric heme, NO(2)(-) was oxidized to a nitrating agent NO(2), and subsequently, tyrosine residues in bovine serum albumin (BSA) were nitrated. However, the presence of NO(2)(-) surprisingly exerted pro-oxidant effect on heme-H(2)O(2)-induced formation of BSA carbonyls at lower concentrations and enhanced the loss of HepG2 cell viability dose-dependently, which was probably due to the ability of this inorganic compound to efficiently enhance the peroxidase activity and oxidative degradation of heme. These data provide novel evidence that the dietary intake and experimental use of NO(2)(-) in vivo and in vitro would possess the pro-oxidant activity through interfering in heme-dependent oxidative reactions. Besides the classic role in protein tyrosine nitration, the deleterious effects on heme redox reactions may provide new insights into the toxicological implications of NO(2)(-) with cellular heme proteins. Copyright © 2011 Elsevier Ltd. All rights reserved.

  11. The Reaction of Oxy Hemoglobin with Nitrite: Mechanism, Antioxidant-Modulated Effect, and Implications for Blood Substitute Evaluation

    Directory of Open Access Journals (Sweden)

    Denisa Hathazi

    2018-02-01

    Full Text Available The autocatalytic reaction between nitrite and the oxy form of globins involves free radicals. For myoglobin (Mb, an initial binding of nitrite to the iron-coordinated oxygen molecule was proposed; the resulting ferrous-peroxynitrate species was not detected, but its decay product, the high-valent ferryl form, was demonstrated in stopped-flow experiments. Reported here are the stopped flow spectra recorded upon mixing oxy Hb (native, as well as chemically-derivatized in the form of several candidates of blood substitutes with a supraphysiological concentration of nitrite. The data may be fitted to a simple kinetic model involving a transient met-aqua form, in contrast to the ferryl detected in the case of Mb in a similar reaction sequence. These data are in line with a previous observation of a transient accumulation of ferryl Hb under auto-catalytic conditions at much lower concentrations of nitrite (Grubina, R. et al. J. Biol. Chem. 2007, 282, 12916. The simple model for fitting the stopped-flow data leaves a small part of the absorbance changes unaccounted for, unless a fourth species is invoked displaying features similar to the oxy and tentatively assigned as ferrous-peroxynitrate. Density functional theory (DFT calculations support this latter assignment. The reaction allows for differentiating between the reactivities of various chemically modified hemoglobins, including candidates for blood substitutes. Polymerization of hemoglobin slows the nitrite-induced oxidation, in sharp contrast to oxidative-stress type reactions which are generally accelerated, not inhibited. Sheep hemoglobin is found to be distinctly more resistant to reaction with nitrite compared to bovine Hb, at large nitrite concentrations (stopped-flow experiments directly observing the oxy + nitrite reaction as well as under auto-catalytic conditions. Copolymerization of Hb with bovine serum albumin (BSA using glutaraldehyde leads to a distinct increase of the lag time

  12. Microbial resource management for the mitigation of nitrous oxide emissions from the Partial Nitritation- Anammox process

    DEFF Research Database (Denmark)

    Blum, Jan-Michael

    Urban wastewater treatment plants are designed to remove pathogens and pollutants from wastewater in order to provide sanitation and to protect receiving water bodies from eutrophication. Reactive nitrogen, mainly in the form of ammonium, is one of the components in wastewater that is converted...... to dinitrogen gas during treatment. The Partial Nitritation-Anammox process (PNA) uses the capacity of autotrophic aerobic and anaerobic ammonia oxidizing bacteria (AOB and AnAOB) to perform this task. The process is mainly applied to treat ammonium-rich wastewater streams with low concentrations of organic...... with the specific ammonia removal rate, while during non-aerated phases net N2O production rates were positively correlated with the nitrite concentration (NO2-). Operation of PNA at reduced specific ammonia removal rates is, therefore, a feasible strategy to mitigate N2O emissions. However, when high ammonium...

  13. Structural basis for dynamic mechanism of nitrate/nitrite antiport by NarK

    Science.gov (United States)

    Fukuda, Masahiro; Takeda, Hironori; Kato, Hideaki E.; Doki, Shintaro; Ito, Koichi; Maturana, Andrés D.; Ishitani, Ryuichiro; Nureki, Osamu

    2015-05-01

    NarK belongs to the nitrate/nitrite porter (NNP) family in the major facilitator superfamily (MFS) and plays a central role in nitrate uptake across the membrane in diverse organisms, including archaea, bacteria, fungi and plants. Although previous studies provided insight into the overall structure and the substrate recognition of NarK, its molecular mechanism, including the driving force for nitrate transport, remained elusive. Here we demonstrate that NarK is a nitrate/nitrite antiporter, using an in vitro reconstituted system. Furthermore, we present the high-resolution crystal structures of NarK from Escherichia coli in the nitrate-bound occluded, nitrate-bound inward-open and apo inward-open states. The integrated structural, functional and computational analyses reveal the nitrate/nitrite antiport mechanism of NarK, in which substrate recognition is coupled to the transport cycle by the concomitant movement of the transmembrane helices and the key tyrosine and arginine residues in the substrate-binding site.

  14. Noble metal catalyzed hydrogen generation from formic acid in nitrite-containing simulated nuclear waste media

    International Nuclear Information System (INIS)

    King, R.B.; Bhattacharyya, N.K.; Wiemers, K.D.

    1994-08-01

    Simulants for the Hanford Waste Vitrification Plant (HWVP) feed containing the major non-radioactive components Al, Cd, Fe, Mn, Nd, Ni, Si, Zr, Na, CO 3 2- , NO 3 -, and NO 2 - were used as media to evaluate the stability of formic acid towards hydrogen evolution by the reaction HCO 2 H → H 2 + CO 2 catalyzed by the noble metals Ru, Rh, and/or Pd found in significant quantities in uranium fission products. Small scale experiments using 40-50 mL of feed simulant in closed glass reactors (250-550 mL total volume) at 80-100 degree C were used to study the effect of nitrite and nitrate ion on the catalytic activities of the noble metals for formic acid decomposition. Reactions were monitored using gas chromatography to analyze the CO 2 , H 2 , NO, and N 2 O in the gas phase as a function of time. Rhodium, which was introduced as soluble RhCl 3 ·3H 2 O, was found to be the most active catalyst for hydrogen generation from formic acid above ∼80 degree C in the presence of nitrite ion in accord with earlier observations. The inherent homogeneous nature of the nitrite-promoted Rh-catalyzed formic acid decomposition is suggested by the approximate pseudo first-order dependence of the hydrogen production rate on Rh concentration. Titration of the typical feed simulants containing carbonate and nitrite with formic acid in the presence of rhodium at the reaction temperature (∼90 degree C) indicates that the nitrite-promoted Rh-catalyzed decomposition of formic acid occurs only after formic acid has reacted with all of the carbonate and nitrite present to form CO 2 and NO/N 2 O, respectively. The catalytic activities of Ru and Pd towards hydrogen generation from formic acid are quite different than those of Rh in that they are inhibited rather than promoted by the presence of nitrite ion

  15. Influence of Addition of Fluid Catalytic Cracking Residue (FCC and the SiO2 Concentration in Alkali-Activated Ceramic Sanitary-Ware (CSW Binders

    Directory of Open Access Journals (Sweden)

    Juan Cosa

    2018-03-01

    Full Text Available Production of Portland cement requires a large volume of natural raw materials and releases huge amounts of CO2 to the atmosphere. Lower environmental impact alternatives focus on alkali-activated cements. In this paper, fluid catalytic cracking residue (FCC was used to partially replace (0 wt %–50 wt % ceramic sanitaryware (CSW in alkali-activated systems. Samples were activated with NaOH and sodium silicate solutions and were cured at 65 °C for 7 days and at 20 °C for 28 and 90 days. In order to increase CSW/FCC binders’ sustainability, the influence of reducing the silica concentration (from 7.28 mol·kg−1 up to 2.91 mol·kg−1 was analyzed. The microstructure of the developed binders was investigated in pastes by X-ray diffraction, thermo tests and field emission scanning electron microscopy analyses. Compressive strength evolution was assessed in mortars. The results showed a synergetic effect of the CSW/FCC combinations so that, under the studied conditions, mechanical properties significantly improved when combining both waste materials (up to 70 MPa were achieved in the mortars containing 50 wt % FCC cured at room temperature for 90 days. Addition of FCC allowed CSW to be activated at room temperature, which significantly broadens the field of applications of alkali-activated CSW binders.

  16. Short-and long-term effects of ammonia and nitrite on the anammox process

    International Nuclear Information System (INIS)

    Fernandez, I.; Campos, J. L.; Mosquera-Corral, A.; Mendez, R.

    2009-01-01

    Auto trophic anaerobic ammonium oxidation (Anammox) process is a feasible alternative to treat industrial wastewater with high ammonia concentration but low content of organic matter. In this process ammonium and nitrite are used by Planctomycete-type bacteria under anoxic conditions to generate nitrogen gas. Both substrates can exert inhibitory effects on the process, causing the decrease of the specific activity of the biomass and the loss of the performance and stability of reactors. (Author)

  17. Nitrate and nitrite in biology, nutrition and therapeutics

    NARCIS (Netherlands)

    Lundberg, J.O.; van Faassen, E.E.H.; Gladwin, M.T.; Ahluwalia, A.; Benjamin, N.

    2009-01-01

    Inorganic nitrate and nitrite from endogenous or dietary sources are metabolized in vivo to nitric oxide (NO) and other bioactive nitrogen oxides. The nitrate-nitrite-NO pathway is emerging as an important mediator of blood flow regulation, cell signaling, energetics and tissue responses to hypoxia.

  18. Amperometric Carbon Fiber Nitrite Microsensor for In Situ Biofilm Monitoring

    Science.gov (United States)

    A highly selective needle type solid state amperometric nitrite microsensor based on direct nitrite oxidation on carbon fiber was developed using a simplified fabrication method. The microsensor’s tip diameter was approximately 7 µm, providing a high spatial resolution of at lea...

  19. Inactivation of Yersinia enterocolitica by nitrite and nitrate in food.

    Science.gov (United States)

    de Giusti, M; de Vito, E

    1992-01-01

    The antimicrobial effects of sodium nitrite and sodium and potassium nitrate against Yersinia enterocolitica were investigated in solution and in treated pork meat. Potassium nitrate and sodium nitrate showed only feeble antimicrobial activity in cultures; no antimicrobial activity was detected with sodium nitrite. Conversely, all three salts displayed apparent antimicrobial activity in pork meat, possibly due to selective effects on competitive flora.

  20. Nitrite as a stimulus for ammonia-starved Nitrosomonas europaea

    NARCIS (Netherlands)

    Laanbroek, H.J.; Bär-Gilissen, M.J.; Hoogveld, H.L.

    2002-01-01

    Ammonia-starved cells of Nitrosomonas europaea are able to preserve a high level of ammonia-oxidizing activity in the absence of ammonium. However, when the nitrite-oxidizing cells that form part of the natural nitrifying community do not keep pace with the ammonia-oxidizing cells, nitrite

  1. NITRITE AND NITRATE DETERMINATIONS IN PLASMA - A CRITICAL-EVALUATION

    NARCIS (Netherlands)

    MOSHAGE, H; KOK, B; HUIZENGA, [No Value; JANSEN, PLM

    Plasma nitrite and nitrate determinations are increasingly being used in clinical chemistry as markers for the activity of nitric oxide synthase and the production of nitric oxide radicals. However, a systematic evaluation of the determination of nitrite and nitrate in plasma has not been performed.

  2. Nitrite and nitrate determinations in plasma: a critical evaluation

    NARCIS (Netherlands)

    Moshage, H.; Kok, B.; Huizenga, J. R.; Jansen, P. L.

    1995-01-01

    Plasma nitrite and nitrate determinations are increasingly being used in clinical chemistry as markers for the activity of nitric oxide synthase and the production of nitric oxide radicals. However, a systematic evaluation of the determination of nitrite and nitrate in plasma has not been performed.

  3. Nitrite enhances liver graft protection against cold ischemia ...

    African Journals Online (AJOL)

    Amani Cherif-Sayadi

    2017-03-30

    Mar 30, 2017 ... cold ischemia reperfusion injury through a NOS ... oxidation and lipid peroxidation remained at low levels in both nitrite-treated groups when ... liver graft preservation [15]. ... nitrite activity is dependent on NO production but .... LiversT rat (n = 6) were flushed and preserved in IGL-1 solution ..... The nitrate-.

  4. Ammonia Oxidation and Nitrite Reduction in the Verrucomicrobial Methanotroph Methylacidiphilum fumariolicum SolV

    Directory of Open Access Journals (Sweden)

    Sepehr S. Mohammadi

    2017-09-01

    Full Text Available The Solfatara volcano near Naples (Italy, the origin of the recently discovered verrucomicrobial methanotroph Methylacidiphilum fumariolicum SolV was shown to contain ammonium (NH4+ at concentrations ranging from 1 to 28 mM. Ammonia (NH3 can be converted to toxic hydroxylamine (NH2OH by the particulate methane monooxygenase (pMMO, the first enzyme of the methane (CH4 oxidation pathway. Methanotrophs rapidly detoxify the intermediate NH2OH. Here, we show that strain SolV performs ammonium oxidation to nitrite at a rate of 48.2 nmol NO2-.h−1.mg DW−1 under O2 limitation in a continuous culture grown on hydrogen (H2 as an electron donor. In addition, strain SolV carries out nitrite reduction at a rate of 74.4 nmol NO2-.h−1.mg DW−1 under anoxic condition at pH 5–6. This range of pH was selected to minimize the chemical conversion of nitrite (NO2- potentially occurring at more acidic pH values. Furthermore, at pH 6, we showed that the affinity constants (Ks of the cells for NH3 vary from 5 to 270 μM in the batch incubations with 0.5–8% (v/v CH4, respectively. Detailed kinetic analysis showed competitive substrate inhibition between CH4 and NH3. Using transcriptome analysis, we showed up-regulation of the gene encoding hydroxylamine dehydrogenase (haoA cells grown on H2/NH4+ compared to the cells grown on CH4/NO3- which do not have to cope with reactive N-compounds. The denitrifying genes nirk and norC showed high expression in H2/NH4+ and CH4/NO3- grown cells compared to cells growing at μmax (with no limitation while the norB gene showed downregulation in CH4/NO3- grown cells. These cells showed a strong upregulation of the genes in nitrate/nitrite assimilation. Our results demonstrate that strain SolV can perform ammonium oxidation producing nitrite. At high concentrations of ammonium this may results in toxic effects. However, at low oxygen concentrations strain SolV is able to reduce nitrite to N2O to cope with this toxicity.

  5. Modeling of Nitrous Oxide Production from Nitritation Reactors Treating Real Anaerobic Digestion Liquor.

    Science.gov (United States)

    Wang, Qilin; Ni, Bing-Jie; Lemaire, Romain; Hao, Xiaodi; Yuan, Zhiguo

    2016-04-29

    In this work, a mathematical model including both ammonium oxidizing bacteria (AOB) and heterotrophic bacteria (HB) is constructed to predict N2O production from the nitritation systems receiving the real anaerobic digestion liquor. This is for the first time that N2O production from such systems was modeled considering both AOB and HB. The model was calibrated and validated using experimental data from both lab- and pilot-scale nitritation reactors. The model predictions matched the dynamic N2O, ammonium, nitrite and chemical oxygen demand data well, supporting the capability of the model. Modeling results indicated that HB are the dominant contributor to N2O production in the above systems with the dissolved oxygen (DO) concentration of 0.5-1.0 mg O2/L, accounting for approximately 75% of N2O production. The modeling results also suggested that the contribution of HB to N2O production decreased with the increasing DO concentrations, from 75% at DO = 0.5 mg O2/L to 25% at DO = 7.0 mg O2/L, with a corresponding increase of the AOB contribution (from 25% to 75%). Similar to HB, the total N2O production rate also decreased dramatically from 0.65 to 0.25 mg N/L/h when DO concentration increased from 0.5 to 7.0 mg O2/L.

  6. Salivary surrogates of plasma nitrite and catecholamines during a 21-week training season in swimmers.

    Directory of Open Access Journals (Sweden)

    Miguel Mauricio Díaz Gómez

    Full Text Available The collection of samples of saliva is noninvasive and straightforward, which turns saliva into an ideal fluid for monitoring the adaptive response to training. Here, we investigated the response of the salivary proteins alpha-amylase (sAA, chromogranin A (sCgA, and the concentration of total protein (sTP as well as salivary nitrite (sNO2 in relation to plasma catecholamines and plasma nitrite (pNO2, respectively. The variation in these markers was compared to the intensity and load of training during a 21-week training season in 12 elite swimmers. Overall, the salivary proteins tracked the concentration of plasma adrenaline and were inversely correlated with the training outcomes. No correlations were observed between sNO2 and pNO2. However, sNO2 correlated positively with the intensity and load of training. We argue that the decrease in sympathetic activity is responsible for the decrease in the concentration of proteins throughout the training season. Furthermore, the increase in nitrite is likely to reflect changes in hemodynamics and regulation of vascular tone. The association of the salivary markers with the training outcomes underlines their potential as noninvasive markers of training status in professional athletes.

  7. Determination of nitrite/nitrate in human biological material by the simple Griess reaction.

    Science.gov (United States)

    Guevara, I; Iwanejko, J; Dembińska-Kieć, A; Pankiewicz, J; Wanat, A; Anna, P; Gołabek, I; Bartuś, S; Malczewska-Malec, M; Szczudlik, A

    1998-06-22

    Since a number of pathological processes such as septic shock, inflammation, graft rejection, diabetes, etc. are associated with a release of nitric oxide (NO), rapid and accurate methods of monitoring of NO concentration are of interest. Various methods for measurement of nitrite and nitrate (NO2-, NO3- ) -- the stable metabolites of NO -- are commonly used for this purpose. In this paper we have shown that the proper Griess procedure for nitrite determination significantly increases the sensitivity of this method. This procedure, supplemented with deproteinization and reduction of nitrates to nitrites in the presence of NADPH-sensitive reductase, can be successfully applied for measurement of NOx levels in human body fluids (serum, urine and CSF). Deproteinization of samples with methanol/diethylether is required and does not influence the sensitivity of detection of NO metabolites. The recovery of the method is 88%+/-6% (n = 30). The NOx concentrations measured by this procedure ranged from 25.0 to 39.0 micromol/l in blood, 4.6 to 14.6 micromol/l in CSF and 0.37 to 2.52 mmol/l (adjusted to creatinine concentration) in urine. The coefficient of variation for this method was between 1.3-2.2%. This method can also be recommended for measurement of NOx produced by cells in tissue cell culture.

  8. Predictors of Plasma DDT and DDE Concentrations among Women Exposed to Indoor Residual Spraying for Malaria Control in the South African Study of Women and Babies (SOWB)

    Science.gov (United States)

    Bornman, Riana M.S.; Archer, Janet I.; Kudumu, Mwenda O.; Travlos, Gregory S.; Wilson, Ralph E.; Longnecker, Matthew P.

    2014-01-01

    regarding home preparations may provide an interventional target. Citation: Whitworth KW, Bornman RM, Archer JI, Kudumu MO, Travlos GS, Wilson RE, Longnecker MP. 2014. Predictors of plasma DDT and DDE concentrations among women exposed to indoor residual spraying for malaria control in the South African Study of Women and Babies (SOWB). Environ Health Perspect 122:545–552; http://dx.doi.org/10.1289/ehp.1307025 PMID:24577839

  9. A random-sequential mechanism for nitrite binding and active site reduction in copper-containing nitrite reductase

    NARCIS (Netherlands)

    Wijma, HJ; Jeuken, LJC; Verbeet, MP; Armstrong, FA; Canters, GW

    2006-01-01

    The homotrimeric copper-containing nitrite reductase ( NiR) contains one type-1 and one type-2 copper center per monomer. Electrons enter through the type-1 site and are shuttled to the type-2 site where nitrite is reduced to nitric oxide. To investigate the catalytic mechanism of NiR the effects of

  10. Increase in nitrite content and functionality of ethanolic extracts of Perilla frutescens following treatment with atmospheric pressure plasma.

    Science.gov (United States)

    Jung, Samooel; Lee, Chul Woo; Lee, Juri; Yong, Hae In; Yum, Su Jin; Jeong, Hee Gon; Jo, Cheorun

    2017-12-15

    This study investigated the effect of atmospheric pressure plasma (APP) treatment on nitrite content and functionality of plant extracts. Ethanolic extracts of Perilla frutescens (EEP) were prepared and treated with APP for 60min. Nitrite content increased from 0 to 45.8mg/l in EEP after APP treatment for 60min. Antimicrobial activity of EEP against Clostridium perfringens and Salmonella Typhimurium was increased by APP with no influence on antioxidative activity (p<0.05). Lyophilized EEP (LEEP) treated with APP for 60min contained 3.74mg/g nitrite. The control (LEEP without APP) contained no nitrite. The minimum inhibitory concentration (MIC) of LEEP for C. perfringens was 200µg/ml. The control did not inhibit C. perfringens growth between 25 and 1000µg/ml. MICs of LEEP and the control against S. Typhimurium were 25 and 50µg/ml, respectively. New nitrite sources with increased antimicrobial activity can be produced from natural plants by APP treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Does nitrite and nitrate levels in drinking water impact the health of people in Dakahlia governorate, Egypt?

    Science.gov (United States)

    Mortada, Wael I; Shokeir, Ahmed A

    2018-05-07

    A total of 1291 drinking water samples were examined for nitrite and nitrate during 6 months from December, 2015 to May, 2016 at 17 cities of Dakahlia governorate (Nile Delta, north of Egypt), and the results were utilized for assessment of health risk of the exposure from drinking water by calculating average daily intake (ADI), hazard quotient (HQ), and the hazard index (HI). The nitrite and nitrate in drinking water had a concentration range of 0.030-0.113 and 2.41-8.70 mg L -1 , with mean values of 0.059 ± 0.014 and 5.25 ± 1.61 mg L -1 , respectively. Nitrite and nitrate levels in rural areas and ground water samples were significantly higher than that in the urban ones. None of the analyzed samples exceeded WHO guideline values that set out to prevent methemoglobinemia. The values of HQ and HI for all age groups do not exceed unity indicating a low risk of methaemoglobinaemia for the population in this area. Results of the present study indicate that there is no health risk of residents from nitrite and nitrate through drinking water in the studied area. However, the other sources of exposure to nitrite and nitrate should be investigated in further studies.

  12. Biological responses of Neotropical freshwater fish Lophiosilurus alexandri exposed to ammonia and nitrite.

    Science.gov (United States)

    Dos Santos Silva, Márcio José; da Costa, Franklin Fernando Batista; Leme, Fabiola Paes; Takata, Rodrigo; Costa, Deliane Cristina; Mattioli, Cristiano Campos; Luz, Ronald Kennedy; Miranda-Filho, Kleber Campos

    2018-03-01

    This study aimed to elucidate the responses of the Neotropical fish Lophiosilurus alexandri exposed to ammonia and nitrite, following a period of recovering. Acute toxicity tests lasted 96h, subchronic toxicity tests lasted eight days and the detoxification trial lasted four days. Groups of 12 juveniles were maintained in 90-L tanks and treated with increasing concentrations of ammonia and nitrite, except during the recovery test. All treatments were performed with two replicates. The median lethal concentrations (LC 50 ) of 24, 48, 72 and 96h were estimated at 30.12; 24.35; 19.24 and 18.68mg·L -1 TA-N; 5.37; 4.57; 3.75 and 3.66mg·L -1 NH 3 -N and 20.37; 7.78; 7.09 and 5.86mg·L -1 NO 2 - -N, respectively. The NO 2 - caused significant decrease in hematocrit and increase in the urea levels during short-term exposure, with recovery of homeostasis after the subchronic and detox period. Acute exposure to ammonia increased the enzyme profile of transaminases, glucose and urea. Urea concentration remained high in the subchronic and detox tests. Histopathologies were observed in animals exposed to ammonia in both toxicity tests. It was highlighted detachment of epithelium, hyperemia and necrosis in the gills. Exposure to NO 2 - caused epithelium detachment and aneurysm. Vacuolization and swelling of hepatocytes were the most common injury for both nitrogenous compounds. We concluded that the L. alexandri has moderate tolerance to ammonia and nitrite. The recovery period revealed remedial response to ammonia and nitrite exposure. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Gewichtsverlies, serumnatriumconcentratie en restverschijnselen bij patiëntjes met hypertone dehydratie door onvoldoende borstvoeding [Weight loss, serum sodium concentration and residual symptoms in patients with hypernatremic dehydration caused by insufficient breastfeeding

    NARCIS (Netherlands)

    Breuning-Boers, J.M.; Dommelen, P. van; Wouwe, J.P. van; Verkerk, P.H.

    2006-01-01

    Objective. To determine the relationship between serum sodium concentration and weight loss as well as residual symptoms in newborns with hypernatremic dehydration caused by insufficient breastfeeding; and to determine the sensitivity of the following rule of thumb 'if weight loss is less than 10%,

  14. Effect of Fermented Spinach as Sources of Pre-Converted Nitrite on Color Development of Cured Pork Loin

    Science.gov (United States)

    Hwang, Ko-Eun

    2017-01-01

    The effect of fermented spinach extracts on color development in cured meats was investigated in this study. The pH values of raw cured meats without addition of fermented spinach extract or nitrite (negative control) were higher (pmeats in treatment groups were decreased with increasing addition levels of fermented spinach extract. The lightness and yellowness values of raw cured meats formulated with fermented spinach extract were higher (pmeats were increased with increasing fermented spinach extract levels, whereas the yellowness values of cooked cured meats were decreased with increasing levels of fermented spinach extract. The lowest volatile basic nitrogen (VBN) and thiobarbituric acid reactive substances (TBARS) values were observed in the positive control group with addition of nitrite. TBARS values of cured meats added with fermented spinach extract were decreased with increasing levels of fermented spinach extract and VBN values of curing meat with 30% fermented spinach extract was lower than the other treatments. Total viable bacterial counts in cured meats added with fermented spinach extract ranged from 0.34-1.01 Log CFU/g. E. coli and coliform bacteria were not observed in any of the cured meats treated with fermented spinach extracts or nitrite. Residual nitrite contents in treatment groups were increased with increasing levels of fermented spinach extract added. These results demonstrated that fermented spinach could be added to meat products to improve own curing characteristics. PMID:28316477

  15. Contamination Detection and Mitigation Strategies for Unsymmetric Dimethylhydrazine/Nitrogen Tetroxide Non-Combustion Product Residues

    Science.gov (United States)

    Greene, Benjamin; Buchanan, Vanessa D.; Baker, David L.

    2006-01-01

    Dimethylamine and nitrite, which are non-combustion reaction products of unsymmetrical dimethylhydrazine (UDMH) and nitrogen tetroxide (NTO) propellants, can contaminate spacesuits during extra-vehicular activity (EVA) operations. They can react with water in the International Space Station (ISS) airlock to form N-nitrosodimethylamine (NDMA), a carcinogen. Detection methods for assessing nitrite and dimethylamine contamination were investigated. The methods are based on color-forming reactions in which intensity of color is proportional to concentration. A concept color detection kit using a commercially available presumptive field test for methamphetamine coupled with nitrite test strips was developed and used to detect dimethylamine and nitrite. Contamination mitigation strategies were also developed.

  16. A comparative study of nitrite reduction by synthetic and biogenic Fe(II-III) hydroxysalts green rusts: Evidence for hydroxyl-nitrite green rust formation as an intermediate reaction product.

    Science.gov (United States)

    Ona-Nguema, G.; Guerbois, D.; Morin, G.; Zhang, Y.; Noel, V.; Brest, J.

    2013-12-01

    The occurrence of high nitrite concentrations as a result of anthropogenic activities is an important water quality concern as it is highly toxic to human and fauna, and it is used as a nitrogen source for the assimilation process. The toxicity of nitrite is related to its transformation into carcinogenic N-nitroso compounds, which are suspected to be responsible for some gastric cancers, and to its ability to convert the hemoglobin to methaemoglobin what is then unable to fix oxygen and to transport it to the tissues, involving hypoxia and the blue-baby syndrome [1]. To reduce the adverse effect of nitrite on human health and on macroalgal blooms, any process enhancing the transformation of nitrite ions to nitrogen gas is of interest for the remediation of natural environments. To achieve this purpose the use of processes involving Fe(II)-containing minerals could be considered as one of the best options. Green-rusts are mixed Fe(II-III) layered double hydroxides commonly found in anoxic zones of natural environments such as sediments and hydromorphic soils. In such anoxic environments, green rust minerals play an important role in the biogeochemical redox cycling of iron and nitrogen, and can affect the speciation and mobility of many organic and inorganic contaminants. The present study investigates the reduction of nitrite by two synthetic and two biogenic green rusts. On the one hand, Fe(II-III) hydroxychloride and Fe(II-III) hydroxycarbonate green rusts were used as synthetic interlayer forms of GR, which are referred to as ';syn-GR(CO3)' and ';syn-GR(Cl)', respectively. On the other hand, the study was performed with biogenic Fe(II-III) hydroxycarbonate green rusts obtained from the bioreduction of two ferric precursors, either Fe(III)-oxyhydroxycarbonate or lepidocrocite; these biogenic green rusts are referred to as ';bio-GR(CO3)F' and ';bio-GR(CO3)L', respectively. For synthetic green rusts, results showed that the oxidation of both syn-GR(CO3) and syn

  17. Use of nitrite inhalants ("poppers") among American youth.

    Science.gov (United States)

    Wu, Li-Tzy; Schlenger, William E; Ringwalt, Chris L

    2005-07-01

    We examined the patterns and correlates of nitrite inhalant use among adolescents aged 12 to 17 years. Study data were drawn from the 2000 and 2001 National Household Surveys on Drug Abuse. Logistic regression was used to identify the characteristics associated with nitrite inhalant use. Among adolescents aged 12 to 17 years, 1.5% reported any lifetime use of nitrite inhalants. The prevalence of lifetime nitrite inhalant use increased to 12% and 14% among adolescents who were dependent on alcohol and any drug in the past year, respectively. Many nitrite inhalant users used at least three other types of inhalants (68%) and also met the criteria for alcohol (33%) and drug (35%) abuse or dependence. Increased odds of nitrite inhalant use were associated with residing in nonmetropolitan areas, recent utilization of mental health services, delinquent behaviors, past year alcohol and drug abuse and dependence, and multi-drug use. Adolescents who had used nitrite inhalants at least once in their lifetime tend to engage in delinquent activities and report co-occurring multiple drug abuse and mental health problems in the past year.

  18. ASPECTS CONCERNING NITRATE AND NITRITE POLLUTION OF GROUNDWATERS

    Directory of Open Access Journals (Sweden)

    A. UNGUREANU

    2011-03-01

    Full Text Available Aspects concerning nitrate and nitrite pollution of groundwaters. Water is a basic natural resource for the good functioning of all thebiological processes in nature. It is very important for life and for the developmentof human activities. The quality of the ground water has begun to degrade moreand more, as a result of the physical, chemical and bacteriological changes.Nitrogen compounds pollution of the underground has increased lately. This hasbeen caused by the excessive and irrational use of nitrogen derived fertilizers, bythe wrong storage of the dejections resulted from zootechnical processes and byother chemical substances discharged into water. Samples were collected fromdifferent wells in order to check whether the well water was drinkable. The resultof the test revealed the existence of high concentrations of nitrates as well asvalues exceeding normal microbiological parameters. The value recorded in thetown of Segarcea, the county of Dolj, showed extremely high concentrations ofnitrates of the drinking water in the wells. Thus, Segarcea is the town with thegreatest number of contaminated wells in the country.

  19. Removal of nitrite impurity from nitrate labeled with nitrogen-15

    International Nuclear Information System (INIS)

    Malone, J.P.; Stevens, R.J.

    1998-01-01

    Potassium nitrate labeled with 15 N is often used as a tracer in studies of N dynamics in soil and water systems. Typically, 0.8% NO 2 - impurity has been found in the batches of K 15 NO 3 enriched to 99 atom % excess 15 N that were purchased by our laboratory. Nitrite is an intermediate in several N cycling processes so its addition when adding NO 3 - could produce misleading results. We have developed a safe, simple, and inexpensive method to remove NO 2 - impurity from any NO 3 - solution in a water matrix. The principle is the oxidation of NO2- to NO 3 - by UV light in the presence of a heterogenous TiO 2 catalyst. A NO 2 - concentration of 0.2 mM in 100 mL of 0.2 M NO 3 - solution could be oxidized in 12 min using 0.5 g L -1 TiO 2 in a specially constructed photoreactor with a 75-W UV facial tanning lamp. For the routine removal of NO 2 - , use of the same TiO 2 concentration in a standard beaker worked equally well when the irradiation time was extended to 2.5 h. After irradiation, the TiO2 is easily and totally removed from the solution by membrane filtration. (author)

  20. A comparison of organic and inorganic nitrates/nitrites.

    Science.gov (United States)

    Omar, Sami A; Artime, Esther; Webb, Andrew J

    2012-05-15

    Although both organic and inorganic nitrates/nitrites mediate their principal effects via nitric oxide, there are many important differences. Inorganic nitrate and nitrite have simple ionic structures and are produced endogenously and are present in the diet, whereas their organic counterparts are far more complex, and, with the exception of ethyl nitrite, are all medicinally synthesised products. These chemical differences underlie the differences in pharmacokinetic properties allowing for different modalities of administration, particularly of organic nitrates, due to the differences in their bioavailability and metabolic profiles. Whilst the enterosalivary circulation is a key pathway for orally ingested inorganic nitrate, preventing an abrupt effect or toxic levels of nitrite and prolonging the effects, this is not used by organic nitrates. The pharmacodynamic differences are even greater; while organic nitrates have potent acute effects causing vasodilation, inorganic nitrite's effects are more subtle and dependent on certain conditions. However, in chronic use, organic nitrates are considerably limited by the development of tolerance and endothelial dysfunction, whereas inorganic nitrate/nitrite may compensate for diminished endothelial function, and tolerance has not been reported. Also, while inorganic nitrate/nitrite has important cytoprotective effects against ischaemia-reperfusion injury, continuous use of organic nitrates may increase injury. While there are concerns that inorganic nitrate/nitrite may induce carcinogenesis, direct evidence of this in humans is lacking. While organic nitrates may continue to dominate the therapeutic arena, this may well change with the increasing recognition of their limitations, and ongoing discovery of beneficial effects and specific advantages of inorganic nitrate/nitrite. Copyright © 2012 Elsevier Inc. All rights reserved.

  1. Nitrates and Nitrites in the Treatment of Ischemic Cardiac Disease

    Science.gov (United States)

    Nossaman, Vaughn E.; Nossaman, Bobby D.; Kadowitz, Philip J.

    2010-01-01

    The organic nitrite, amyl of nitrite, was initially used as a therapeutic agent in the treatment of angina pectoris in 1867, but was replaced over a decade later by the organic nitrate, nitroglycerin (NTG), due to the ease of administration and longer duration of action. The administration of organic nitrate esters, such as NTG, continues to be used in the treatment of angina pectoris and heart failure during the birth of modern pharmacology. The clinical effectiveness is due to vasodilator activity in large veins and arteries through an as yet unidentified method of delivering nitric oxide (NO), or a NO-like compound to vascular smooth muscle cells. The major drawback with NTG administration is the rapid development of tolerance; and with amyl of nitrite, the duration and route of administration. Although amyl of nitrite are no longer used in the treatments of hypertension or ischemic heart disease, the nitrite anion has recently been discovered to possess novel pharmacologic actions such as modulating hypoxic vasodilation and providing cytoprotection in ischemia-reperfusion injury. Although the actions of these two similar chemical classes (nitrites and organic nitrates) have often been considered to be alike, we still do not understand their mechanism of action. However, the recent discovery that the nitrite anion, derived from either sodium nitrite or an intermediate NTG form, may act as a storage form for NO and provides support for investigating the use of these agents in the treatment of ischemic cardiovascular states. We review what is presently known about the use of nitrites and nitrates, the potential uses of these agents, and their mechanisms of action. PMID:20539102

  2. Nitrite-embedded packaging film effects on fresh and frozen beef color development and stability as influenced by meat age and muscle type.

    Science.gov (United States)

    Claus, James R; Du, Chen

    2013-11-01

    Muscles (Longissimus lumborum, LL; Psoas major, PM, semitendinosus, ST) were aged (2, 9d postmortem), cut into steaks, anaerobically packaged (nitrite-embedded film, NEF), and displayed (fresh, 19d; frozen, 39d). Fresh NEF increased (PMeat age influenced NEF color. Intact NEF maintained acceptable red color throughout display. Residual nitrite and nitrate associated with fresh NEF and nitrate in NEF cooked LL were found (Pmeat age and muscle differences. NEF packaging has potential to extend fresh beef color display life. NEF appears to offer the opportunity to display bright red beef in frozen display by limiting typical effects of photooxidation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Hypoxia tolerance, nitric oxide, and nitrite: Lessons from extreme animals

    DEFF Research Database (Denmark)

    Fago, Angela; B. Jensen, Frank

    2015-01-01

    survival resides in concerted physiological responses, including strong metabolic depression, protection against oxidative damage and – in air breathing animals - redistribution of blood flow. Each of these responses is known to be tightly regulated by nitric oxide (NO) and during hypoxia by its metabolite...... nitrite. The aim of this review is to highlight recent work illustrating the widespread roles of NO and nitrite in the tolerance to extreme oxygen deprivation, in particular in the red-eared slider turtle and crucian carp, but also in diving marine mammals. The emerging picture underscores the importance...... of NO and nitrite signaling in the adaptive response to hypoxia in vertebrate animals....

  4. The inhibitory effects of free ammonia on ammonia oxidizing bacteria and nitrite oxidizing bacteria under anaerobic condition.

    Science.gov (United States)

    Qian, Wenting; Peng, Yongzhen; Li, Xiyao; Zhang, Qiong; Ma, Bin

    2017-11-01

    The free ammonia (FA) inhibition on ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) under anaerobic condition was investigated in this study. The results indicated that NOB was more sensitive to the FA anaerobic treatment than AOB. The FA anaerobic inhibition on nitrifier gradually heightened with the increase of FA concentration. Accompanied with FA concentration increase from 0 to 16.82mgNH 3 -N·L -1 (the highest concentration adopted in this study), the activity of AOB reduced by 15.9%, while NOB decreased by 29.2%. After FA anaerobic treatment, nitrite was accumulated during nitrification. However, the nitrite accumulation disappeared on the sixth cycle of activity recovery tests with excessive aeration. Based on this result, a novel strategy for achieving nitritation is proposed, which involves recirculating a portion of the activated sludge through a side-line sludge treatment unit, where the sludge is subjected to treatment with FA under anaerobic condition. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Acetylation and glycation of fibrinogen in vitro occur at specific lysine residues in a concentration dependent manner: A mass spectrometric and isotope labeling study

    International Nuclear Information System (INIS)

    Svensson, Jan; Bergman, Ann-Charlotte; Adamson, Ulf; Blombäck, Margareta; Wallén, Håkan; Jörneskog, Gun

    2012-01-01

    Highlights: ► Fibrinogen was incubated in vitro with glucose or aspirin. ► Acetylations and glycations were found at twelve lysine sites by mass spectrometry. ► The labeling by aspirin and glucose occurred dose-dependently. ► No competition between glucose and aspirin for binding to fibrinogen was found. -- Abstract: Aspirin may exert part of its antithrombotic effects through platelet-independent mechanisms. Diabetes is a condition in which the beneficial effects of aspirin are less prominent or absent – a phenomenon called “aspirin resistance”. We investigated whether acetylation and glycation occur at specific sites in fibrinogen and if competition between glucose and aspirin in binding to fibrinogen occurs. Our hypothesis was that such competition might be one explanation to “aspirin resistance” in diabetes. After incubation of fibrinogen in vitro with aspirin (0.8 mM, 24 h) or glucose (100 mM, 5–10 days), we found 12 modified sites with mass spectrometric techniques. Acetylations in the α-chain: αK191, αK208, αK224, αK429, αK457, αK539, αK562, in the β-chain: βK233, and in the γ-chain: γK170 and γK273. Glycations were found at βK133 and γK75, alternatively γK85. Notably, the lysine 539 is a site involved in FXIII-mediated cross-linking of fibrin. With isotope labeling in vitro, using [ 14 C-acetyl]salicylic acid and [ 14 C]glucose, a labeling of 0.013–0.084 and 0.12–0.5 mol of acetylated and glycated adduct/mol fibrinogen, respectively, was found for clinically (12.9–100 μM aspirin) and physiologically (2–8 mM glucose) relevant plasma concentrations. No competition between acetylation and glycation could be demonstrated. Thus, fibrinogen is acetylated at several lysine residues, some of which are involved in the cross-linking of fibrinogen. This may mechanistically explain why aspirin facilitates fibrin degradation. We find no support for the idea that glycation of fibrin(ogen) interferes with acetylation of

  6. Acetylation and glycation of fibrinogen in vitro occur at specific lysine residues in a concentration dependent manner: A mass spectrometric and isotope labeling study

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, Jan, E-mail: jan.svensson@ki.se [Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital (Solna), SE-171 76 Stockholm (Sweden); Karolinska Institutet, Department of Clinical Sciences, Danderyd Hospital, SE-182 88 Stockholm (Sweden); Bergman, Ann-Charlotte [Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital (Solna), SE-171 76 Stockholm (Sweden); Adamson, Ulf [Karolinska Institutet, Department of Clinical Sciences, Danderyd Hospital, SE-182 88 Stockholm (Sweden); Blombaeck, Margareta [Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital (Solna), SE-171 76 Stockholm (Sweden); Wallen, Hakan; Joerneskog, Gun [Karolinska Institutet, Department of Clinical Sciences, Danderyd Hospital, SE-182 88 Stockholm (Sweden)

    2012-05-04

    Highlights: Black-Right-Pointing-Pointer Fibrinogen was incubated in vitro with glucose or aspirin. Black-Right-Pointing-Pointer Acetylations and glycations were found at twelve lysine sites by mass spectrometry. Black-Right-Pointing-Pointer The labeling by aspirin and glucose occurred dose-dependently. Black-Right-Pointing-Pointer No competition between glucose and aspirin for binding to fibrinogen was found. -- Abstract: Aspirin may exert part of its antithrombotic effects through platelet-independent mechanisms. Diabetes is a condition in which the beneficial effects of aspirin are less prominent or absent - a phenomenon called 'aspirin resistance'. We investigated whether acetylation and glycation occur at specific sites in fibrinogen and if competition between glucose and aspirin in binding to fibrinogen occurs. Our hypothesis was that such competition might be one explanation to 'aspirin resistance' in diabetes. After incubation of fibrinogen in vitro with aspirin (0.8 mM, 24 h) or glucose (100 mM, 5-10 days), we found 12 modified sites with mass spectrometric techniques. Acetylations in the {alpha}-chain: {alpha}K191, {alpha}K208, {alpha}K224, {alpha}K429, {alpha}K457, {alpha}K539, {alpha}K562, in the {beta}-chain: {beta}K233, and in the {gamma}-chain: {gamma}K170 and {gamma}K273. Glycations were found at {beta}K133 and {gamma}K75, alternatively {gamma}K85. Notably, the lysine 539 is a site involved in FXIII-mediated cross-linking of fibrin. With isotope labeling in vitro, using [{sup 14}C-acetyl]salicylic acid and [{sup 14}C]glucose, a labeling of 0.013-0.084 and 0.12-0.5 mol of acetylated and glycated adduct/mol fibrinogen, respectively, was found for clinically (12.9-100 {mu}M aspirin) and physiologically (2-8 mM glucose) relevant plasma concentrations. No competition between acetylation and glycation could be demonstrated. Thus, fibrinogen is acetylated at several lysine residues, some of which are involved in the cross-linking of

  7. Cloning and characterization of a nitrite reductase gene related to ...

    African Journals Online (AJOL)

    STORAGESEVER

    2010-03-01

    Mar 1, 2010 ... Alexander et al., 2005) and heme-type nitrite reductase gene (Smith and ... owing to a genotype-dependent response (Zhang et al.,. 1991; Sakhanokho et al., ..... Improvement of cell culture conditions for rice. Jpn. Agric. Res.

  8. Analysis of nitrites and nitrates in hams and sausages by open-tubular capillary electrochromatography with a nanolatex-coated capillary column.

    Science.gov (United States)

    Zhang, Yanhao; Tian, Xiangyu; Guo, Yaxiao; Li, Haibin; Yu, Ajuan; Deng, Zhifen; Sun, Barry Baoguo; Zhang, Shusheng

    2014-04-16

    In this work, a new open-tubular capillary electrochromatography (OT-CEC) method with the nanolatex-coated column was proposed for the determination of nitrites and nitrates in foodstuffs. The method was simple and repeatable as a result of avoiding the introduction of an electroosmotic flow reverse additive (such as cetyltrimethylammonium chloride) in electrophoretic buffer. The limits of quantitation were 0.89 and 1.05 mg kg⁻¹ for nitrate and nitrite, respectively, whereas the overall recoveries ranged from 94 to 103%. The developed OT-CEC method was successfully applied for 12 samples, and the residue profiles of nitrites and nitrates in hams and sausages were obtained and evaluated.

  9. Correlation of plasma nitrite/nitrate levels and inducible nitric oxide gene expression among women with cervical abnormalities and cancer.

    Science.gov (United States)

    Sowjanya, A Pavani; Rao, Meera; Vedantham, Haripriya; Kalpana, Basany; Poli, Usha Rani; Marks, Morgan A; Sujatha, M

    2016-01-30

    Cervical cancer is caused by infection with high risk human papillomavirus (HR-HPV). Inducible nitric oxide synthase (iNOS), a soluble factor involved in chronic inflammation, may modulate cervical cancer risk among HPV infected women. The aim of the study was to measure and correlate plasma nitrite/nitrate levels with tissue specific expression of iNOS mRNA among women with different grades of cervical lesions and cervical cancer. Tissue biopsy and plasma specimens were collected from 120 women with cervical neoplasia or cancer (ASCUS, LSIL, HSIL and invasive cancer) and 35 women without cervical abnormalities. Inducible nitric oxide synthase (iNOS) mRNA from biopsy and plasma nitrite/nitrate levels of the same study subjects were measured. Single nucleotide polymorphism (SNP) analysis was performed on the promoter region and Ser608Leu (rs2297518) in exon 16 of the iNOS gene. Differences in iNOS gene expression and plasma nitrite/nitrate levels were compared across disease stage using linear and logistic regression analysis. Compared to normal controls, women diagnosed with HSIL or invasive cancer had a significantly higher concentration of plasma nitrite/nitrate and a higher median fold-change in iNOS mRNA gene expression. Genotyping of the promoter region showed three different variations: A pentanucleotide repeat (CCTTT) n, -1026T > G (rs2779249) and a novel variant -1153T > A. These variants were associated with increased levels of plasma nitrite/nitrate across all disease stages. The higher expression of iNOS mRNA and plasma nitrite/nitrate among women with pre-cancerous lesions suggests a role for nitric oxide in the natural history of cervical cancer. Copyright © 2015. Published by Elsevier Inc.

  10. The levels of nitrite and nitrate, proline and protein profiles in tomato plants infected with pseudomonas syringae

    International Nuclear Information System (INIS)

    Berber, I.; Onlu, H.

    2012-01-01

    In this study, the contents of nitrite-nitrate and free L-proline, and pathogenesis-related (PR) proteins in tomato plants following inoculation with Pseudomonas syringae pv. tomato strain were examined. The results of the nitrite and nitrate indicated that there was a reduction in the levels of nitrate in the infected tomato plants through 1-8 study days, compared with the healthy plants. On the other hands, when the nitrite amounts increased in the first and second days, the nitrite concentrations reduced in infected plants at subsequent time periods, compared with uninfected plants. The accumulation of free proline increased in the infected plants, according to control plants. The whole-cell protein profiles displayed that the levels of the protein bands of molecular masses 204.6 kDa and 69.9 kDa significantly increased in infected and uninfected plants during 2-10 study days. In additionally, in the quantities of the protein bands of molecular weights 90.3 and 79.4 kDa were observed an increase in the infected and healthy plants after the fourth day. However, the protein band of molecular weight 54.3 kDa was visible only in uninfected plants for the fourth and eighth days. Finally, the study suggest that there were the sophisticate relationships among the proline accumulation, the conversion of nitrate to nitrite and the induction of PR protein genes in the regulation of defense mechanisms toward microbial invaders. Our results also indicated that the increases in nitrite and proline contents might be useful indicator for the response toward pathogen attacks. (author)

  11. Nitrite uptake by nitrogen-depleted wheat seedlings

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, W A; Johnson, R E; Volk, R J

    1974-01-01

    Intact, 14-day-old nitrogen-depleted wheat (Triticum vulgare cv. Blueboy) seedlings were exposed to solutions of 0.5 mM KNO/sub 2/, 0.05 mM CaSO/sub 4/ and 1 mM sodium 2-(N-morpholino)-ethanesulfonate, pH 6.1. Nitrite uptake was determined from depletion of the ambient solution or from incorporation of /sup 15/N in the tissue. An initial nitrite uptake shoulder was followed by a relatively slow uptake rate which subsequently increased to a substantially greater rate. This accelerated phase was maintained through 24 h. Nitrite accumulated to a slight extent in the root tissues during the first few hours but declined to low values when the accelerated rate was fully developed, indicating an increase in nitrite reductase activity paralleling the increase in nitrite uptake capacity. About 50% of the nitrogen absorbed as nitrite was translocated to the shoots by 9 to 12 h. Development of the accelerated nitrite uptake rate was restricted in excised roots, in intact plants kept in darkness, by 400 ..mu..g puromycin ml/sup -1/ and by 1 mM L-ethionine. When puromycin and L-ethionine were added after the accelerated phase had been initiated, their effects were not as detrimental as when they were added at first exposure to KNO/sub 2/. The two inhibitors restricted translocation more than uptake. The data indicate an involvement of protein synthesis and a requirement for movement of a substance from shoots to roots for maximal development of the accelerated nitrite uptake phase. A requirement for protein synthesis in the transport of soluble organic nitrogen from roots to shoots is also suggested.

  12. Influence of irradiation on reaction products of nitrite in foodstuffs

    International Nuclear Information System (INIS)

    Mirna, A.; Rau, G.

    1982-01-01

    Nitro alkanes and nitrolic acids are formed in foods by nitrosation reactions with nitrite. Among TEA-responsive compounds nitrolic acid behave to irradiation similar to N-nitrosamines. Some substances, extracted from spices, especially garlic, are also detectable by GC/TEA-chromatogramms of meat products and of reaction products from spices with nitrite show retention times not always clearly differentiated from those of NDMA, NDEA, NPIP and NPYR, respectively. Additional confirmation of such TEA positive compounds, therefore, is necessary. (orig.) [de

  13. Mitochondria recycle nitrite back to the bioregulator nitric monoxide

    International Nuclear Information System (INIS)

    Nohl, H.; Staniek, K.; Sobhian, B.; Bahrami, S.; Redl, H.; Kozlov, A.V.

    2000-01-01

    Nitric monoxide (NO) exerts a great variety of physiological functions. L-Arginine supplies amino groups which are transformed to NO in various NO-synthase-active isoenzyme complexes. NO-synthesis is stimulated under various conditions increasing the tissue of stable NO-metabolites. The major oxidation product found is nitrite. Elevated nitrite levels were reported to exist in a variety of diseases including HIV, reperfusion injury and hypovolemic shock. Denitrifying bacteria such as Paracoccus denitrificans have a membrane bound set of cytochromes (cyt cd 1 , cyt bc) which were shown to be involved in nitrite reduction activities. Mammalian mitochondria have similar cytochromes which form part of the respiratory chain. Like in bacteria quinols are used as reductants of these types of cytochromes. The observation of one-e - divergence from this redox-couple to external dioxygen made us to study whether this site of the respiratory chain may also recycle nitrite back to its bioactive form NO. Thus, the aim of the present study was therefore to confirm the existence of a reductive pathway which reestablishes the existence of the bioregulator NO from its main metabolite NO 2 - . Our results show that respiring mitochondria readily reduce added nitrite to NO which was made visible by nitrosylation of deoxyhemoglobin. The adduct gives characteristic triplet-ESR-signals. Using inhibitors of the respiratory chain for chemical sequestration of respiratory segments we were able to identify the site where nitrite is reduced. The results confirm the ubiquinone/cyt bc 1 couple as the reductant site where nitrite is recycled. The high affinity of NO to the heme-iron of cytochrome oxidase will result in an impairment of mitochondrial energy-production. ''Nitrite tolerance'' of angina pectoris patients using NO-donors may be explained in that way. (author)

  14. Effects of Processing Temperature on Color Properties of Dry-Cured Hams Made without Nitrite

    Directory of Open Access Journals (Sweden)

    Giovanni Parolari

    2016-04-01

    Full Text Available Dry cured hams were investigated for their ability to develop red color even at low temperature (3–4 °C and in the absence of added nitrites; results were compared with those obtained from nitrite-free hams made at conventional warm maturing temperatures. Colorimetric parameters (L*, a*, b*, and hue and concentration of the main pigments Zn protoporphyrin IX (ZnPP and heme were measured at three stages of preparation (six, nine, and 12 months, showing that red color was successfully formed at low temperatures, though at a slower rate and less intensively than under warm conditions. Major differences in the pattern of color development were found with the two processing temperatures. While the typical features of an enzyme-dependent mechanism, with a progressive drop in enzyme activity paralleling the synthesis of Zn protoporphyrin IX, were observed at warm temperatures, the same did not occur in cold-made hams, where the enzyme activity was almost unchanged throughout the process. These results, along with data from a descriptive sensory analysis, are supportive of a non-enzymatic mechanism leading to ZnPP (hence the red color under cold conditions, with an estimated three-month delay compared with nitrite-free hams manufactured in a warm maturing regimen.

  15. Effects of Processing Temperature on Color Properties of Dry-Cured Hams Made without Nitrite.

    Science.gov (United States)

    Parolari, Giovanni; Aguzzoni, Agnese; Toscani, Tania

    2016-04-29

    Dry cured hams were investigated for their ability to develop red color even at low temperature (3-4 °C) and in the absence of added nitrites; results were compared with those obtained from nitrite-free hams made at conventional warm maturing temperatures. Colorimetric parameters (L*, a*, b*, and hue) and concentration of the main pigments Zn protoporphyrin IX (ZnPP) and heme were measured at three stages of preparation (six, nine, and 12 months), showing that red color was successfully formed at low temperatures, though at a slower rate and less intensively than under warm conditions. Major differences in the pattern of color development were found with the two processing temperatures. While the typical features of an enzyme-dependent mechanism, with a progressive drop in enzyme activity paralleling the synthesis of Zn protoporphyrin IX, were observed at warm temperatures, the same did not occur in cold-made hams, where the enzyme activity was almost unchanged throughout the process. These results, along with data from a descriptive sensory analysis, are supportive of a non-enzymatic mechanism leading to ZnPP (hence the red color) under cold conditions, with an estimated three-month delay compared with nitrite-free hams manufactured in a warm maturing regimen.

  16. Effects of Processing Temperature on Color Properties of Dry-Cured Hams Made without Nitrite

    Science.gov (United States)

    Parolari, Giovanni; Aguzzoni, Agnese; Toscani, Tania

    2016-01-01

    Dry cured hams were investigated for their ability to develop red color even at low temperature (3–4 °C) and in the absence of added nitrites; results were compared with those obtained from nitrite-free hams made at conventional warm maturing temperatures. Colorimetric parameters (L*, a*, b*, and hue) and concentration of the main pigments Zn protoporphyrin IX (ZnPP) and heme were measured at three stages of preparation (six, nine, and 12 months), showing that red color was successfully formed at low temperatures, though at a slower rate and less intensively than under warm conditions. Major differences in the pattern of color development were found with the two processing temperatures. While the typical features of an enzyme-dependent mechanism, with a progressive drop in enzyme activity paralleling the synthesis of Zn protoporphyrin IX, were observed at warm temperatures, the same did not occur in cold-made hams, where the enzyme activity was almost unchanged throughout the process. These results, along with data from a descriptive sensory analysis, are supportive of a non-enzymatic mechanism leading to ZnPP (hence the red color) under cold conditions, with an estimated three-month delay compared with nitrite-free hams manufactured in a warm maturing regimen. PMID:28231128

  17. Mutagenicity of some alkyl nitrites used as recreational drugs

    Energy Technology Data Exchange (ETDEWEB)

    Dunkel, V.C.; Cameron, T.P. (National Institute of Health, Bethesda (USA)); Rogers-Back, A.M.; Lawlor, T.E.; Harbell, J.W. (Microbiological Associates Inc., Rockville, MD (USA))

    1989-01-01

    When the AIDS epidemic was in its earliest stages, and prior to identification of HIV as the etiological factor, the use of volatile nitrites by the male homosexual community to enhance sexual activities appeared to have a significant role in this disease. Preliminary observations indicated that that portion of the male homosexual community which developed Kaposi's sarcoma were also heavy nitrite users. These nitrites had been demonstrated to be mutagenic in bacteria and thus it was postulated that they could be responsible for the appearance of the sarcoma. To evaluate further the genotoxic activity of these chemicals, six nitrites, including those most commonly used by homosexuals for sexual gratification, were selected for testing in the mouse lymphoma TK {plus minus} and Salmonell typhimurium mutagenicity assays. One chemical, n-amyl nitrite, was negative in the mouse lymphoma assay, while the other five chemicals, n-butyl, isobutyl, iso-amyl, sec-butyl, and n-propyl nitrite, were positive. All six compounds were positive in the Salmonella assay. The mutagenic and known toxic effects of these chemicals remain a concern because a large population of teenagers and young adults continue to abuse these substances.

  18. Supporting palladium metal on gold nanoparticles improves its catalysis for nitrite reduction.

    Science.gov (United States)

    Qian, Huifeng; Zhao, Zhun; Velazquez, Juan C; Pretzer, Lori A; Heck, Kimberly N; Wong, Michael S

    2014-01-07

    Nitrate (NO3(-)) and nitrite (NO2(-)) anions are often found in groundwater and surface water as contaminants globally, especially in agricultural areas due to nitrate-rich fertilizer use. One popular approach to studying the removal of nitrite/nitrate from water has been their degradation to dinitrogen via Pd-based reduction catalysis. However, little progress has been made towards understanding how the catalyst structure can improve activity. Focusing on the catalytic reduction of nitrite in this study, we report that Au NPs supporting Pd metal ("Pd-on-Au NPs") show catalytic activity that varies with volcano-shape dependence on Pd surface coverage. At room temperature, in CO2-buffered water, and under H2 headspace, the NPs were maximally active at a Pd surface coverage of 80%, with a first-order rate constant (k(cat) = 576 L g(Pd)(-1) min(-1)) that was 15x and 7.5x higher than monometallic Pd NPs (~4 nm; 40 L g(Pd)(-1) min(-1)) and Pd/Al2O3 (1 wt% Pd; 76 L g(Pd)(-1) min(-1)), respectively. Accounting only for surface Pd atoms, these NPs (576 L g(surface-Pd)(-1) min(-1)) were 3.6x and 1.6x higher than monometallic Pd NPs (160 L g(surface-Pd)(-1) min(-1)) and Pd/Al2O3 (361 L g(surface-Pd)(-1) min(-1)). These NPs retained ~98% of catalytic activity at a chloride concentration of 1 mM, whereas Pd/Al2O3 lost ~50%. The Pd-on-Au nanostructure is a promising approach to improve the catalytic reduction process for nitrite and, with further development, also for nitrate anions.

  19. The role of natural organic matter in nitrite formation by LP-UV/H2O2 treatment of nitrate-rich water.

    Science.gov (United States)

    Semitsoglou-Tsiapou, Sofia; Mous, Astrid; Templeton, Michael R; Graham, Nigel J D; Hernández Leal, Lucía; Kruithof, Joop C

    2016-12-01

    The role of natural organic matter (NOM) on nitrite formation from nitrate photolysis by low pressure ultraviolet lamp (LP-UV) photolysis and LP-UV/H 2 O 2 treatment was investigated. Nitrate levels up to the WHO guideline maximum of 50 mg NO 3 - /L were used in tests. The presence of 4 mg/L Suwannee River natural organic matter (NOM) led to increased nitrite yields compared to NOM-free controls. This was caused partly by NOM scavenging of OH radicals, preserving the produced NO 2 - as well as the ONOO - that leads to NO 2 - formation, but also via the production of radical species ( 1 O 2 , O 2 - and OH) by the photolysis of NOM. In addition, solvated electrons formed by NOM photolysis may reduce nitrate directly to nitrite. For comparison, Nordic Lake NOM, representative of aquatic NOM, as well as Pony Lake NOM, which had a greater nitrogen content (6.51% w/w) than the other two types of NOM, were investigated, yielding similar nitrite levels as Suwannee River NOM. The results suggest that neither the type nor the nitrogen content of the NOM have an effect on the nitrite yields obtained over the range of UV/H 2 O 2 doses applied (UV fluences of 500-2100 mJ/cm 2 and hydrogen peroxide doses of 10, 25, and 50 mg/L). The findings indicate that for UV fluences above 1500 mJ/cm 2 the resulting nitrite concentration can exceed the 0.1 mg/L EU regulatory limit for nitrite, suggesting that nitrite formation by LP-UV advanced oxidation of nitrate-rich waters is important to consider. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Improving yield and composition of protein concentrates from green tea residue in an agri-food supply chain: Effect of pre-treatment

    NARCIS (Netherlands)

    Zhang, Chen; Krimpen, Van Marinus M.; Sanders, Johan P.M.; Bruins, Marieke E.

    2016-01-01

    Rather than improving crop-production yield, developing biorefinery technology for unused biomass from the agri-food supply chain may be the crucial factor to reach sustainable global food security. A successful example of food-driven biorefinery is the extraction of protein from green tea residues,

  1. Nitritation and denitritation of ammonium-rich wastewater using fluidized-bed biofilm reactors

    Energy Technology Data Exchange (ETDEWEB)

    Aslan, Sukru [Cumhuriyet University, Department of Environmental Engineering, 58140 Sivas (Turkey)], E-mail: saslan@cumhuriyet.edu.tr; Dahab, Mohamed [Department of Civil Engineering, University of Nebraska-Lincoln, W348 Nebraska Hall, Lincoln, NE 68588 (United States)

    2008-08-15

    Fluidized-bed biofilm nitritation and denitritation reactors (FBBNR and FBBDR) were operated to eliminate the high concentrations of nitrogen by nitritation and denitritation process. The dissolved oxygen (DO) concentration was varied from 1.5 to 2.5 g/m{sup 3} at the top of the reactor throughout the experiment. NH{sub 4}-N conversion and NO{sub 2}-N accumulation in the nitritation reactor effluent was over 90 and 65%, respectively. The average NH{sub 4}-N removal efficiency was 99.2 and 90.1% at the NLR of 0.9 and 1.2 kg NH{sub 4}-N/m{sup 3} day, respectively. Increasing the NLR from 1.1 to 1.2 kg NH{sub 4}-N/m{sup 3} day decreased the NH{sub 4}-N elimination approximately two-fold while NH{sub 4}-N conversion to NO{sub 2}-N differences were negligible. The NO{sub 2}-N/NO{sub x}-N ratios corresponded to 0.74, 0.73, 0.72, and 0.69, respectively, indicating the occurrence of partial nitrification. An average free ammonia concentration in the FBBNR was high enough to inhibit nitrite oxidizers selectively, and it seems to be a determining factor for NO{sub 2}-N accumulation in the process. In the FBBDR, the NO{sub x}-N (NO{sub 2}-N + NO{sub 3}-N) concentrations supplied were between 227 and 330 mg N/l (NLR was between 0.08 and 0.4 kg/m{sup 3} day) and the influent flow was increased as long as the total nitrogen removal was close to 90%. The NO{sub 2}-N and NO{sub 3}-N concentrations in the effluent were 3.0 and 0.9 mg/l at 0.08 kg/m{sup 3} day loading rate. About 98% removal of NO{sub x}-N was achieved at the lowest NLR in the FBBDR. The FBBDR exhibited high nitrogen removal up to the NLR of 0.25 kg/m{sup 3} day. The NO{sub x}-N effluent concentration never exceeded 15 mg/l. The total nitrogen removal efficiency in the FBBRs was higher than 93% at 21 {+-} 1 deg. C.

  2. Annual and seasonal variation of turbidity, total dissolved solids, nitrate and nitrite in the Parsabad water treatment plant, Iran

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Zare

    2013-01-01

    Full Text Available Aims: This study investigated the annual and seasonal variation of turbidity; total dissolved solid (TDS, nitrate and nitrite in Parsabad water treatment plant (WTP, Iran. Materials and Methods: The water samples were obtained from the inlet and outlet of Parsabad WTP from February 2002 to June 2009. The samples′ turbidity, TDS, nitrate, nitrite, pH, and temperature were measured according to standard methods once a month and the average of these parameters were calculated for each season of year. Results: The maximum concentration of inlet turbidity, TDS, nitrate and nitrite were 691, 700.5, 25, and 0.17 mg/l, respectively. These parameters for outlet samples in the study period were 3.0, 696.7, 18, and 0.06 mg/l, respectively. While these concentrations in outlet zone were lower than World Health Organization (WHO or United States Environmental Protection Agency (US-EPA water quality guidelines, WTP could not reduce the TDS, nitrate, nitrite and pH value and these parameters were not different in the inlet and outlet samples. However, the WTP reduced the turbidity significantly with an efficiency of up to 85%. Conclusion: This study showed that a common WTP with rapid sand filtration can treat a maximum river turbidity of 700 NTU in several years. As no differences were observed between inlet and outlet TDS, nitrate, nitrite and pH in the studied WTP. It can be concluded that compensatory schemes should be predicted for modification of these parameters when they exceed the standards in the emergency situations.

  3. Uncovering the local inelastic interactions during manufacture of ductile cast iron: How the substructure of the graphite particles can induce residual stress concentrations in the matrix

    DEFF Research Database (Denmark)

    Andriollo, Tito; Hellström, Kristina; Sonne, Mads Rostgaard

    2018-01-01

    Recent X-ray diffraction (XRD) measurements have revealed that plastic deformation and a residual elastic strain field can be present around the graphite particles in ductile cast iron after manufacturing, probably due to some local mismatch in thermal contraction. However, as only one component...... of the elastic strain tensor could be obtained from the XRD data, the shape and magnitude of the associated residual stress field have remained unknown. To compensate for this and to provide theoretical insight into this unexplored topic, a combined experimental-numerical approach is presented in this paper...... the graphite particles and the matrix during manufacturing of the industrial part considered in the XRD study. The model indicates that, besides the vis- coplastic deformation of the matrix, the effect of the inelastic deformation of the graphite has to be considered to explain the magnitude of the XRD strain...

  4. Serum nitrate and nitrite are associated with the prevalence of various chronic diseases except cancer.

    Science.gov (United States)

    Gumanova, Nadezhda G; Deev, Alexander D; Klimushina, Marina V; Kots, Alexander Y; Shalnova, Svetlana A

    2017-04-01

    Nitric oxide and its metabolites, nitrate and nitrite, are important regulators linked to various diseases. We studied the association of fasting serum concentrations of nitrate and nitrite, combined as NOx, without special diet, with the prevalence of various chronic diseases. Fasting concentrations of NOx were assayed in a cohort of 1087 patients recruited to Stress Aging and Health in Russia study that represents male and female population in Moscow, Russia, over 55 years of age. Chronic diseases were recorded based on anamnesis and additional assays were run to characterize immune status and lipid and carbohydrate metabolism. Odds ratios were calculated to associate NOx concentrations with prevalence of chronic diseases in pooled deciles below or above borderline. NOx over 44.7 µM were associated with increased prevalence of various chronic diseases such as diabetes type II, hyperthyroidism, coronary heart disease, gout and thrombosis/stroke. NOx 65.3 µM and above were associated with lowered prevalence of osteoporosis. NOx levels of 74.6 µM and above were associated with significantly higher number of patients who abstain from consumption of alcoholic beverages. NOx were not associated with cancer. Thus, fasting concentrations of NOx in serum can be an important diagnostic parameter characteristic for specific chronic diseases.

  5. Nitrogen removal from sludge digester liquids by nitrification/denitrification or partial nitritation/anammox: environmental and economical considerations.

    Science.gov (United States)

    Fux, C; Siegrist, H

    2004-01-01

    In wastewater treatment plants with anaerobic sludge digestion, 15-20% of the nitrogen load is recirculated to the main stream with the return liquors from dewatering. Separate treatment of this ammonium-rich digester supernatant significantly reduces the nitrogen load of the activated sludge system. Two biological applications are considered for nitrogen elimination: (i) classical autotrophic nitrification/heterotrophic denitrification and (ii) partial nitritation/autotrophic anaerobic ammonium oxidation (anammox). With both applications 85-90% nitrogen removal can be achieved, but there are considerable differences in terms of sustainability and costs. The final gaseous products for heterotrophic denitrification are generally not measured and are assumed to be nitrogen gas (N2). However, significant nitrous oxide (N2O) production can occur at elevated nitrite concentrations in the reactor. Denitrification via nitrite instead of nitrate has been promoted in recent years in order to reduce the oxygen and the organic carbon requirements. Obviously this "achievement" turns out to be rather disadvantageous from an overall environmental point of view. On the other hand no unfavorable intermediates are emitted during anaerobic ammonium oxidation. A cost estimate for both applications demonstrates that partial nitritation/anammox is also more economical than classical nitrification/denitrification. Therefore autotrophic nitrogen elimination should be used in future to treat ammonium-rich sludge liquors.

  6. Heme-Induced Biomarkers Associated with Red Meat Promotion of colon Cancer Are Not Modulated by the Intake of Nitrite

    Science.gov (United States)

    Chenni, Fatima Z; Taché, Sylviane; Naud, Nathalie; Guéraud, Françoise; Hobbs, Ditte A; Kunhle, Gunter G C; Pierre, Fabrice H; Corpet, Denis E

    2013-01-01

    Red and processed meat consumption is associated with the risk of colorectal cancer. Three hypotheses are proposed to explain this association, via heme/alcenal, heterocyclic amines or N-nitroso compounds. Rats have often been used to study these hypotheses, but the lack of enterosalivary cycle of nitrate in rats casts doubt on the relevance of this animal model to predict nitroso- and heme-associated human colon carcinogenesis. The present study was thus designed to clarify whether a nitrite intake that mimics the enterosalivary cycle can modulate heme-induced nitrosation and fat peroxidation. This study shows that, in contrast with the starting hypothesis, salivary nitrite did not change the effect of hemoglobin on biochemical markers linked to colon carcinogenesis, notably lipid peroxidation and cytotoxic activity in the colon of rat. However, ingested sodium nitrite increased fecal nitroso-compounds level, but their fecal concentration and their nature (iron-nitrosyl) would not be associated with an increased risk of cancer. The rat model could thus be relevant to study the effect of red meat on colon carcinogenesis in spite of the lack of nitrite recycling in rat’s saliva. PMID:23441609

  7. Determination of nitrate and nitrite in Hanford defense waste (HDW) by reverse polarity capillary zone electrophoresis (RPCE) method

    International Nuclear Information System (INIS)

    Metcalf, S.G.

    1998-01-01

    This paper describes the first application of reverse polarity capillary zone electrophoresis (RPCE) for rapid and accurate determination of nitrate and nitrite in Hanford Defense Waste (HDW). The method development was carried out by using Synthetic Hanford Waste (SHW), followed by the analysis of 4 real HDW samples. Hexamethonium bromide (HMB) was used as electroosmotic flow modifier in borate buffer at pH 9.2 to decrease the electroosmotic flow (EOF) in order to enhance the speed of analysis and the resolution of nitrate and nitrite in high ionic strength HDW samples. The application of this capillary zone electrophoresis method, when compared with ion chromatography for two major components of HDW, nitrate and nitrite slightly reduced analysis time, eliminated most pre-analysis handling of the highly radioactive sample, and cut analysis wastes by more than 2 orders of magnitude. The analysis of real HDW samples that were validated by using sample spikes showed a concentration range of 1.03 to 1.42 M for both nitrate. The migration times of the real HDW and the spiked HDW samples were within a precision of less than 3% relative standard deviation. The selectivity ratio test used for peak confirmation of the spiked samples was within 96% of the real sample. Method reliability was tested by spiking the matrix with 72.4 mM nitrate and nitrite. Recoveries for these spiked samples were 93-103%

  8. Mainstream upflow nitritation-anammox system with hybrid anaerobic pretreatment: Long-term performance and microbial community dynamics.

    Science.gov (United States)

    Li, Xiaojin; Sun, Shan; Yuan, Heyang; Badgley, Brian D; He, Zhen

    2017-11-15

    Mainstream nitritation-anammox is of strong interest to energy- and resource-efficient domestic wastewater treatment. However, there lack in-depth studies of pretreatment, tests of actual wastewater, and examination of long-term performance. Herein, an upflow nitritation-anammox granular reactor has been investigated to treat primary effluent with a hybrid anaerobic reactor (HAR) as pretreatment for more than 300 days. This system achieved 92% of COD removal, 75% of which was accomplished by the HAR, and had an average final effluent COD concentration of 22 mg L -1 . More than 90% of ammonium was removed in the nitritation-anammox reactor, achieving a nitrogen removal rate of 81.0 g N m -3  d -1 in the last stage. The accumulation of sulfate-reducing bacteria in the HAR evidenced the effect of sulfate on COD removal and subsequent nitrogen removal. Anammox bacteria (predominantly Ca. Jettenia asiatica) accounted for up to 40.2% of total granular communities, but their abundance decreased over time in the suspended communities. The dynamics of major metabolisms and functional genes involved in nitrogen conversion were predicted by PICRUSt based on the taxonomic data, providing more insights into the functions of the microbial communities. These results have demonstrated the effectiveness and importance of anaerobic pretreatment to successful mainstream nitritation-anammox. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. The role of nitrite and nitrate ions as photosensitizers in the phototransformation of phenolic compounds in seawater

    Energy Technology Data Exchange (ETDEWEB)

    Calza, P., E-mail: paola.calza@unito.it [Universita degli Studi di Torino, Dipartimento di Chimica, Via P. Giuria 5, 10125 Torino (Italy); Vione, D. [Universita degli Studi di Torino, Dipartimento di Chimica, Via P. Giuria 5, 10125 Torino (Italy); Universita degli Studi di Torino, Centro Interdipartimentale NatRisk, Via Leonardo da Vinci 44, 10095 Grugliasco (Italy); Novelli, A. [Max Planck Institute for Chemistry, 55128 Mainz (Germany); Pelizzetti, E.; Minero, C. [Universita degli Studi di Torino, Dipartimento di Chimica, Via P. Giuria 5, 10125 Torino (Italy)

    2012-11-15

    Nitrite and nitrate are known to be involved in photochemical processes occurring in natural waters. In this study we have investigated the role played by these photosensitizers towards the transformation of xenobiotic organic matter in marine water, with the goal of assessing the typical transformation routes induced in seawater by irradiated nitrite/nitrate. For this purpose, phenol was chosen as model molecule. Phenol transformation was investigated under simulated solar radiation in the presence of nitrite (in the range of 1 Multiplication-Sign 10{sup -5}-1 Multiplication-Sign 10{sup -2} M) or nitrate ions, in pure water at pH 8, in artificial seawater (containing same dissolved salts as seawater but no organic matter), and in natural seawater. In all experiments, phenol degradation rate and formation of intermediates were assessed. As expected, phenol disappearance rate decreased with decreasing nitrite concentration and was slightly reduced by the presence of chloride. Other salts present in artificial seawater (e.g. HCO{sub 3}{sup -}, CO{sub 3}{sup 2-} and Br{sup -}) had a more marked effect on phenol transformation. Analysis of intermediates formed in the different matrices under study showed generation of hydroxyl-, nitro- and chloroderivatives of phenol, to a different extent depending on experimental conditions. 1,4-Benzoquinone prevailed in all cases, nitroderivatives were only formed with nitrite but were not detected in nitrate-spiked solutions. Competition was observed between halogenation and nitration of phenol, with variable outcome depending on nitrite concentration. The most likely reason is competition between nitrating and halogenating species for reaction with the phenoxyl radical. A kinetic model able to justify the occurrence of different intermediates under the adopted conditions is presented and discussed. -- Highlights: Black-Right-Pointing-Pointer Nitrite and nitrate-mediated solar-driven transformations of pollutant in seawater were

  10. The role of nitrite and nitrate ions as photosensitizers in the phototransformation of phenolic compounds in seawater

    International Nuclear Information System (INIS)

    Calza, P.; Vione, D.; Novelli, A.; Pelizzetti, E.; Minero, C.

    2012-01-01

    Nitrite and nitrate are known to be involved in photochemical processes occurring in natural waters. In this study we have investigated the role played by these photosensitizers towards the transformation of xenobiotic organic matter in marine water, with the goal of assessing the typical transformation routes induced in seawater by irradiated nitrite/nitrate. For this purpose, phenol was chosen as model molecule. Phenol transformation was investigated under simulated solar radiation in the presence of nitrite (in the range of 1 × 10 −5 –1 × 10 −2 M) or nitrate ions, in pure water at pH 8, in artificial seawater (containing same dissolved salts as seawater but no organic matter), and in natural seawater. In all experiments, phenol degradation rate and formation of intermediates were assessed. As expected, phenol disappearance rate decreased with decreasing nitrite concentration and was slightly reduced by the presence of chloride. Other salts present in artificial seawater (e.g. HCO 3 − , CO 3 2− and Br − ) had a more marked effect on phenol transformation. Analysis of intermediates formed in the different matrices under study showed generation of hydroxyl-, nitro- and chloroderivatives of phenol, to a different extent depending on experimental conditions. 1,4-Benzoquinone prevailed in all cases, nitroderivatives were only formed with nitrite but were not detected in nitrate-spiked solutions. Competition was observed between halogenation and nitration of phenol, with variable outcome depending on nitrite concentration. The most likely reason is competition between nitrating and halogenating species for reaction with the phenoxyl radical. A kinetic model able to justify the occurrence of different intermediates under the adopted conditions is presented and discussed. -- Highlights: ► Nitrite and nitrate-mediated solar-driven transformations of pollutant in seawater were studied. ► Phenol degradation rate and formation of intermediates were assessed

  11. Sodium nitrite: the "cure" for nitric oxide insufficiency.

    Science.gov (United States)

    Parthasarathy, Deepa K; Bryan, Nathan S

    2012-11-01

    This process of "curing" food is a long practice that dates back thousands of years long before refrigeration or food safety regulations. Today food safety and mass manufacturing are dependent upon safe and effective means to cure and preserve foods including meats. Nitrite remains the most effective curing agent to prevent food spoilage and bacterial contamination. Despite decades of rigorous research on its safety and efficacy as a curing agent, it is still regarded by many as a toxic undesirable food additive. However, research within the biomedical science community has revealed enormous therapeutic benefits of nitrite that is currently being developed as novel therapies for conditions associated with nitric oxide (NO) insufficiency. Much of the same biochemistry that has been understood for decades in the meat industry has been rediscovered in human physiology. This review will highlight the fundamental biochemistry of nitrite in human physiology and highlight the risk benefit evaluation surrounding nitrite in food and meat products. Foods or diets enriched with nitrite can have profound positive health benefits. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Relation between nitrate and nitrite food habits with lung cancer.

    Science.gov (United States)

    Karimzadeh, Laleh; Koohdani, Fariba; Siassi, Fereydoon; Mahmoudi, Mahmoud; Moslemi, Daryoush; Safari, Farid

    2012-01-01

    Nitrites, a probable human carcinogen, generate reactive nitrogen species that may cause damage to the lung. We evaluated the association between nutritional habits related to nitrite and nitrate intake and risk of lung cancer in Mazandaran, Northern Province of Iran. In this case-control study the two groups were matched for gender and age (+/- 5 years). A semi -quantitative food frequency questionnaire (FFQ) was used to collect dietary data about nutritional habits related to nitrate, nitrite, vitamins E and C intake, from 40 lung cancer cases and 40 control subjects admitted at Mazanaran hospitals. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) for the risk of lung cancer using logistic regression. Mean score of nutritional habits in case group was significantly lower than that in control group (P less than or equal 0.001). We observed a positive association between animal sources of nitrate and nitrite intake (OR = 2.7, 95% CI: 0.13-0.96) and risk of lung cancer. Decreased risk of lung cancer was also observed with fruit intake (OR = 0.26, 95% CI: 1.3-11). Our results indicate a probable association between nutritional habits related to animal sources of nitrate and nitrite intake and the risk of lung cancer that requires to be confirmed by other studies.

  13. Dietary nitrate and nitrite: Benefits, risks, and evolving perceptions.

    Science.gov (United States)

    Bedale, Wendy; Sindelar, Jeffrey J; Milkowski, Andrew L

    2016-10-01

    Consumers have an illogical relationship with nitrite (and its precursor, nitrate) in food. Despite a long history of use, nitrite was nearly banned from use in foods in the 1970s due to health concerns related to the potential for carcinogenic nitrosamine formation. Changes in meat processing methods reduced those potential risks, and nitrite continued to be used in foods. Since then, two opposing movements continue to shape how consumers view dietary nitrate and nitrite. The discovery of the profound physiological importance of nitric oxide led to the realization that dietary nitrate contributes significantly to the nitrogen reservoir for nitric oxide formation. Numerous clinical studies have also demonstrated beneficial effects from dietary nitrate consumption, especially in vascular and metabolic health. However, the latest wave of consumer sentiment against food additives, the clean-label movement, has renewed consumer fear and avoidance of preservatives, including nitrite. Education is necessary but may not be sufficient to resolve this disconnect in consumer perception. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Acidified nitrite inhibits proliferation of Listeria monocytogenes - Transcriptional analysis of a preservation method.

    Science.gov (United States)

    Müller-Herbst, Stefanie; Wüstner, Stefanie; Kabisch, Jan; Pichner, Rohtraud; Scherer, Siegfried

    2016-06-02

    Sodium nitrite (NaNO2) is added as a preservative during raw meat processing such as raw sausage production to inhibit growth of pathogenic bacteria. In the present study it was shown in challenge assays that the addition of sodium nitrite indeed inhibited growth and survival of Listeria monocytogenes in short-ripened spreadable raw sausages. Furthermore, in vitro growth analyses were performed, which took into account combinations of various parameters of the raw sausage ripening process like temperature, oxygen availability, pH, NaCl concentration, and absence or presence of NaNO2. Data based on 300 growth conditions revealed that the inhibitory effect of nitrite was most prominent in combination with acidification, a combination that is also achieved during short-ripened spreadable raw sausage production. At pH6.0 and below, L. monocytogenes was unable to replicate in the presence of 200mg/l NaNO2. During the adaptation of L. monocytogenes to acidified nitrite stress (pH6.0, 200mg/l NaNO2) in comparison to acid exposure only (pH6.0, 0mg/l NaNO2), a massive transcriptional adaptation was observed using microarray analyses. In total, 202 genes were up-regulated and 204 genes were down-regulated. In accordance with growth inhibition, a down-regulation of genes encoding for proteins which are involved in central cellular processes, like cell wall/membrane/envelope biogenesis, translation and ribosomal structure and biogenesis, transcription, and replication, recombination and repair, was observed. Among the up-regulated genes the most prominent group belonged to poorly characterized genes. A considerable fraction of the up-regulated genes has been shown previously to be up-regulated intracellularly in macrophages, after exposure to acid shock or to be part of the SigB regulon. These data indicate that the adaptation to acidified nitrite partly overlaps with the adaptation to stress conditions being present during host colonization. Copyright © 2016 Elsevier B

  15. Effect of ascorbate, nitrate and nitrite on the amount of flavour compounds produced from leucine by Staphylococcus xylosus and Staphylococcus carnosus

    DEFF Research Database (Denmark)

    Olesen, Pelle Thonning; Stahnke, Louise Heller; Talon, R.

    2004-01-01

    Resting cells of Staphylococcus xylosus and S. carnosus were incubated with ascorbate, nitrate and nitrite in defined reaction medium and their degradation of H-3-labelled leucine into methyl-branched catabolites were studied using HPLC/radiometric detection. The experiments were carried out...... of nitrite and nitrate for S. xylosus. Addition of alpha-ketoglutarate generally increased the concentration of 3-methylbutanoic acid for both S. xylosus and S. carnosus....... with and without addition of alpha-ketoglutarate. The main catabolic product of leucine degradation was 3-methylbutanoic acid but also small amounts of alpha-hydroxy isocaproic acid were produced. Nitrite addition lowered the concentration of 3-methylbutanoic acid for both Staphylococcus species and this effect...

  16. Control of residual carbon concentration in GaN high electron mobility transistor and realization of high-resistance GaN grown by metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    He, X.G. [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Zhao, D.G., E-mail: dgzhao@red.semi.ac.cn [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Jiang, D.S.; Liu, Z.S.; Chen, P.; Le, L.C.; Yang, J.; Li, X.J. [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Zhang, S.M.; Zhu, J.J.; Wang, H.; Yang, H. [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215125 (China)

    2014-08-01

    GaN films were grown by metal-organic chemical vapor deposition (MOCVD) under various growth conditions. The influences of MOCVD growth parameters, i.e., growth pressure, ammonia (NH{sub 3}) flux, growth temperature, trimethyl-gallium flux and H{sub 2} flux, on residual carbon concentration ([C]) were systematically investigated. Secondary ion mass spectroscopy measurements show that [C] can be effectively modulated by growth conditions. Especially, it can increase by reducing growth pressure up to two orders of magnitude. High-resistance (HR) GaN epilayer with a resistivity over 1.0 × 10{sup 9} Ω·cm is achieved by reducing growth pressure. The mechanism of the formation of HR GaN epilayer is discussed. An Al{sub x}Ga{sub 1−x}N/GaN high electron mobility transistor structure with a HR GaN buffer layer and an additional low-carbon GaN channel layer is presented, exhibiting a high two dimensional electron gas mobility of 1815 cm{sup 2}/Vs. - Highlights: • Influence of MOCVD parameters on residual carbon concentration in GaN is studied. • GaN layer with a resistivity over 1 × 10{sup 9} Ω·cm is achieved by reducing growth pressure. • High electron mobility transistor (HEMT) structures were prepared. • Control of residual carbon content results in HEMT with high 2-D electron gas mobility.

  17. A rapid and sensitive evaluation of nitrite content in Saudi Arabian processed meat and poultry using a novel ultra performance liquid chromatography-mass spectrometry method.

    Science.gov (United States)

    Siddiqui, Masoom Raza; Wabaidur, Saikh Mohammad; Khan, Moonis Ali; ALOthman, Zeid A; Rafiquee, M Z A; Alqadami, Ayoub Abdullah

    2018-01-01

    Quantitative assessment of nitrite (NO 2 - ) anion was performed using a newly developed high throughput ultra performance liquid chromatography-mass spectrometric (UPLC-MS) method. The nitrite determination with the proposed method using micellar mobile phase was unknown. Selected ion reaction mode using negative electrospray ionization was adopted for the identification and quantitative analysis of nitrite. The chromatographic separation was performed using BEH C-18 column and a micellar mobile phase consisted of sodium dodecyl sulphate and acetonitrile in ratio 30:70 was used. The elution of nitrite anion was accomplished in less than 1 min. Under the optimal analysis conditions, the linearity of the developed method was checked in the concentration range of 0.5-20 mg kg -1 NO 2 - with an excellent correlation coefficient of 0.996. The precisions of the method with relative standard deviation <2% was observed when standard at concentration of 1 mg kg -1 was used. The limit of detection and limit of quantitation of the developed mass spectrometric method was found to be 0.114 and 0.346 mg kg -1 , respectively. The developed UPLC/MS method was applied to quantify this anion in processed meats and poultries from various super market of Saudi Arabia (Riyadh region). The recoveries of the nitrite in the various samples were found in the range of 100.03-103.5%.

  18. Seasonal and Water Column Trends of the Relative Role of Nitrate and Nitrite as ·OH Sources in Surface Waters

    International Nuclear Information System (INIS)

    Vione, D.; Minero, C.; Maurino, V.; Pelizzetti, E.

    2007-01-01

    Based on literature data of sunlight spectrum, photolysis quantum yields, and absorption spectra, the relative role of nitrite and nitrate as ·OH sources in surface waters was assessed, and its dependence on the season and the depth of the water column studied. In the majority of surface water samples (river, lake and seawater) nitrite is expected to play a more important role as ·OH source compared to nitrate, in spite of the usually lower [NO 2 - ] values. Interestingly, under the hypothesis of a constant ratio of the concentrations of nitrate and nitrite (to be corrected later on for the actual concentration ratio in a given sample), the relative role of nitrite compared to nitrate would be minimum in summer, at noon, in the surface layer of natural waters. Any decrease in the sunlight intensity that can be experienced in the natural environment (different season than summer, water column absorption, time of the day other than the solar noon), with its associated influence on the sunlight spectrum, would increase the relative role of nitrite compared to nitrate

  19. Intracellular conversion of environmental nitrate and nitrite to nitric oxide with resulting developmental toxicity to the crustacean Daphnia magna.

    Directory of Open Access Journals (Sweden)

    Bethany R Hannas

    2010-08-01

    Full Text Available Nitrate and nitrite (jointly referred to herein as NO(x are ubiquitous environmental contaminants to which aquatic organisms are at particularly high risk of exposure. We tested the hypothesis that NO(x undergo intracellular conversion to the potent signaling molecule nitric oxide resulting in the disruption of endocrine-regulated processes.These experiments were performed with insect cells (Drosophila S2 and whole organisms Daphnia magna. We first evaluated the ability of cells to convert nitrate (NO(3(- and nitrite (NO(2(- to nitric oxide using amperometric real-time nitric oxide detection. Both NO(3(- and NO(2(- were converted to nitric oxide in a substrate concentration-dependent manner. Further, nitric oxide trapping and fluorescent visualization studies revealed that perinatal daphnids readily convert NO(2(- to nitric oxide. Next, daphnids were continuously exposed to concentrations of the nitric oxide-donor sodium nitroprusside (positive control and to concentrations of NO(3(- and NO(2(-. All three compounds interfered with normal embryo development and reduced daphnid fecundity. Developmental abnormalities were characteristic of those elicited by compounds that interfere with ecdysteroid signaling. However, no compelling evidence was generated to indicate that nitric oxide reduced ecdysteroid titers.Results demonstrate that nitrite elicits developmental and reproductive toxicity at environmentally relevant concentrations due likely to its intracellular conversion to nitric oxide.

  20. Analysis of PWR auxiliary coolant: determination of chloride in borax/nitrite solution by known addition - known dilution potentiometry

    International Nuclear Information System (INIS)

    Midgley, D.; Gatford, C.

    1989-11-01

    Chloride concentrations of 75-250 μg 1 -1 have been determined in simulated PWR auxiliary coolant containing 1000 mg l -1 each of sodium tetraborate and sodium nitrite. The effects of the two main components of the coolant solution on a variety of chloride-selective electrodes have been studied. Sodium tetraborate posed no problem except through its effect on the pH, which is easily adjusted. Such high concentrations of nitrite, however, caused significant deviations in e.m.f. for all the electrodes and marked tarnishing of the electroactive membrane after only one or two measurements. Sulphamic acid was selected as the best means of removing nitrite and silver chloride electrodes were preferred over mercury(I) chloride electrodes because of their greater robustness in the conditions. At these chloride concentrations, the electrodes are operating in their non-Nernstian response regions and direct potentiometry has poor precision, even if standards could be successfully matched to samples containing such high concentrations of background material. Known addition - known dilution potentiometry was adopted, with internal calibration for both slope factor and standard potential. (author)

  1. Reduction of nitrate and nitrite salts under hydrothermal conditions

    International Nuclear Information System (INIS)

    Foy, B.R.; Dell'Orco, P.C.; Wilmanns, E.; McInroy, R.; Ely, J.; Robinson, J.M.; Buelow, S.J.

    1994-01-01

    The feasibility of reducing nitrate/nitrite salts under hydrothermal conditions for the treatment of aqueous mixed wastes stored in the underground tanks at the Department of Energy site at Hanford, Washington was studied. The reduction of nitrate and nitrite salts by reaction with EDTA using a tank waste simulant was examined at temperatures between 623K and 800K and pressures between 0.6 and 1.2 kbar. Continuous flow reactors were used to determine kinetics and products of reactions. All reactions were studied under pressures high enough to produce single phase conditions. The reactions are rapid, go to completion in less than a minute, and produce simple products, such as carbonate, nitrogen, and nitrous oxide gases. The experimental results demonstrate the ability of chemical reactions under hydrothermal conditions to reduce the nitrate and nitrite salts and destroy organic compounds in the waste mixtures

  2. Changes in mutagenicity of protein pyrolyzates by reaction with nitrite.

    Science.gov (United States)

    Yoshida, D; Matsumoto, T

    1978-09-01

    Pyrolyzates of protein and related materials were treated with nitrite under acidic conditions, and the mutagenic activity toward Salmonella tester strains was determined. After treatment with nitrite in acidic solution, casein pyrolyzate, an extract of roasted chicken meat, tobacco-smoke condensate and some aromatic amines showed appreciable decreases in their mutagenic activities toward Salmonella typhimurium TA 98. Aromatic amines in the pyrolyzates may be changed by nitrite treatment to other forms having no or lower mutagenic activity toward Salmonella typhimurium TA 98. The contribution by aromatic amines to the total mutagenic activity of the pyrolyzates was as high as 80% in both casein pyrolyzate and extract of roasted chicken meat and 50% in tobacco-smoke condensate. Pyrolyzates of protein and related materials did not show a decrease in the mutagenic activity toward Salmonella typhimurium TA 100 with the same treatment.

  3. Energetics and kinetics of ferrocyanide and nitrate/nitrite reactions

    International Nuclear Information System (INIS)

    Scheele, R.D.; Burger, L.L.; Sell, R.L.

    1994-01-01

    During the 1950's, radiocesium scavenging at the Hanford site resulted in radioactive waste sludges containing ferrocyanide, nitrate, and nitrite. These waters are a concern since certain mixtures of ferrocyanide and nitrate and/or nitrite are known to explode when heated. The authors have used differential scanning calorimetry, thermogravimetric analysis, isothermal calorimetry and gravimetry, and accelerating rate calorimetry to measure the thermal behavior, the reaction enthalpies, and selected kinetic parameters for reactions between sodium nickel ferrocyanide, the suspected ferrocyanide form in Hanford wastes, and nitrate and/or nitrite. These studies indicate that the oxidation proceeds via multiple steps, the initial reaction begins near 200 degrees C, the initial step has a high activation energy (>200 kJ/mole-K), succeeding reaction steps have activation energies ranging from 90 to 160 kJ/mole-K, and that the oxidation yields about 50% of the theoretical heat of reaction for the most energetic reaction

  4. Residual stresses

    International Nuclear Information System (INIS)

    Sahotra, I.M.

    2006-01-01

    The principal effect of unloading a material strained into the plastic range is to create a permanent set (plastic deformation), which if restricted somehow, gives rise to a system of self-balancing within the same member or reaction balanced by other members of the structure., known as residual stresses. These stresses stay there as locked-in stresses, in the body or a part of it in the absence of any external loading. Residual stresses are induced during hot-rolling and welding differential cooling, cold-forming and extruding: cold straightening and spot heating, fabrication and forced fitting of components constraining the structure to a particular geometry. The areas which cool more quickly develop residual compressive stresses, while the slower cooling areas develop residual tensile stresses, and a self-balancing or reaction balanced system of residual stresses is formed. The phenomenon of residual stresses is the most challenging in its application in surface modification techniques determining endurance mechanism against fracture and fatigue failures. This paper discusses the mechanism of residual stresses, that how the residual stresses are fanned and what their behavior is under the action of external forces. Such as in the case of a circular bar under limit torque, rectangular beam under limt moment, reclaiming of shafts welds and peening etc. (author)

  5. Effect of ozonation on microbial fish pathogens, ammonia, nitrate, nitrite, and bod in simulated reuse hatchery water

    Energy Technology Data Exchange (ETDEWEB)

    Colberg, P.J.; Lingg, A.J.

    1978-10-01

    The effectiveness of ozone for eliminating fish pathogens and reducing nitrite, ammonia, and BOD associated with reuse hatchery systems was evaluated. Comparative survival rates of four bacterial fish pathogens and a bacterium-protozoan population during batch and continuous flow ozonation indicated a specific microbial ozone demand during batch treatment and 99% mortality of pathogens during continuous flow treatment. Oxidation of carbon and nitrite by ozone was rapid at low ozone concentrations; carbon and ammonia oxidation rates were pH dependent. The oxidation capacity of ozone in water was greatest at elevated pH even though lower ozone concentrations were used. Ozone treatment appears to be successful for disinfecting hatchery makeup water for recycling. However, the economics of such treatment are yet to be determined. (10 graphs, 28 references, 1 table)

  6. Effects of Pre-Converted Nitrite from Red Beet and Ascorbic Acid on Quality Characteristics in Meat Emulsions

    Science.gov (United States)

    Kim, Hyun-Wook; Hwang, Ko-Eun

    2017-01-01

    We investigated the effects of fermented red beet extract and ascorbic acid on color development in meat emulsions. The pH of meat emulsions containing red beet extract decreased with an increase in the amount of extract added. The redness of the treated meat emulsions was higher than that of the control with no added nitrite or fermented red beet extract (pmeat emulsions treated with fermented red beet extract only was lower than in that treated with both fermented red beet extract and ascorbic acid (pmeat emulsions treated with fermented red beet extract were higher than in that treated with both fermented red beet extract and ascorbic acid (pmeat emulsions tested. Treatment T2, containing nitrite and ascorbic acid, had the highest overall acceptability score (pnitrite from red beet extract and 0.05% ascorbic acid (p>0.05). The residual nitrite content of the meat emulsions treated with ascorbic acid was lower than in those treated without ascorbic acid (pnitrite for the stability of color development in meat emulsions. PMID:28515652

  7. Aeration Strategies To Mitigate Nitrous Oxide Emissions from Single-Stage Nitritation/Anammox Reactors

    DEFF Research Database (Denmark)

    Domingo Felez, Carlos; Mutlu, A. Gizem; Jensen, Marlene Mark

    2014-01-01

    Autotrophic nitrogen removal is regarded as a resource efficient process to manage nitrogen-rich residual streams. However, nitrous oxide emissions of these processes are poorly documented and strategies to mitigate emissions unknown. In this study, two sequencing batch reactors performing single...... was noted when the duration of aeration was increased while decreasing air flow rate (10.9 +/- 3.2% Delta N2O/Delta TN). The extant ammonium oxidation activity (mgNH(4)(+)-N/gVSS.min) positively correlated with the specific N2O production rate (mgN(2)O-N/gVSS.min) of the systems. Operating under conditions......-stage nitritation/anammox were operated under different aeration strategies, gradually adjusted over six months. At constant but limiting oxygen loading, synthetic reject water was fed (0.75g-N/L.d) and high nitrogen removal efficiencies (83 +/- 5 and 88 +/- 2%) obtained. Dynamics of liquid phase nitrous (N2O...

  8. Flow-injection analysis of nitrate by reduction to nitrite and gas-phase molecular absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Haghighi, B.; Tavassoli, A. [Dept. of Chemistry, Inst. for Advanced Studies in Basic Sciences, Zanjan (Iran)

    2001-12-01

    Two flow-injection manifolds have been investigated for the determination of nitrate. These manifolds are based on the reduction of nitrate to nitrite and determination of nitrite by gas-phase molecular absorption spectrophotometry. Nitrate sample solution (300 {mu}L) which is injected to the flow line, is reduced to nitrite by reaction with hydrazine or passage through the on-line copperized cadmium (Cd-Cu) reduction column. The nitrite produced reacts with a stream of hydrochloric acid and the evolved gases are purged into the stream of O{sub 2}carrier gas. The gaseous phase is separated from the liquid phase using a gas-liquid separator and then swept into a flow-through cell which has been positioned in the cell compartment of an UV-visible spectrophotometer. The absorbance of the gaseous phase is measured at 204.7 nm. A linear relationship was obtained between the intensity of absorption signals and concentration of nitrate when Cd-Cu reduction method was used, but a logarithmic relationship was obtained when the hydrazine reduction method was used. By use of the Cd-Cu reduction method, up to 330 {mu}g of nitrate was determined. The limit of detection was 2.97 {mu}g nitrate and the relative standard deviations for the determination of 12.0, 30.0 and 150 {mu}g nitrate were 3.32, 3.87 and 3.6%, respectively. Maximum sampling rate was approximately 30 samples per hour. The Cd-Cu reduction method was applied to the determination of nitrate and the simultaneous determination of nitrate and nitrite in meat products, vegetables, urine, and a water sample. (orig.)

  9. Equilibrium of particle nitrite with gas phase HONO: Tropospheric measurements in the high Arctic during polar sunrise

    Science.gov (United States)

    Li, Shao-Meng

    1994-12-01

    Gas phase HONO(g) and nitrite in particles of formation rate from HONO(g) photolysis was greater than from the photolysis of both O3 and CH2O by more than one order of magnitude during the sunlit period and led to moderately high levels of OH, e.g., 3×105 molecules cm-3 OH at noontime on April 5. Particle nitrite measurements showed a gradual increase in concentrations with increasing solar insolation, but the concentrations were generally less than 10 ppt. The pH and the sulfate molar concentrations of the particles and the water vapor mixing ratio indicate that the particles were highly acidic being approximately 70% (W/W) H2SO4 solution. In such highly concentrated H2SO4 solution, most particle nitrite should exist as hydrated nitrosonium ion H2ONO+. Taking this into consideration, the particle nitrite was in an approximate equilibrium with the measured HONO(g). This equilibrium, with HONO(g) rapidly photolyzed, was a good indication that the particles were effective sources of HONO(g) and implied rapid production of particle N(+III) during this period. Two possible pathways leading to the formation of particle N(+III) species are suggested, i.e., reduction of HNO3(aq) by SO2(g) and reduction of NO3-; (aq) by Br- (aq). However, N2O5 reaction with NaBr cannot be ruled out as the alternative HONO(g) formation mechanism which bypasses the equilibrium.

  10. Residual stresses

    International Nuclear Information System (INIS)

    Macherauch, E.

    1978-01-01

    Residual stresses are stresses which exist in a material without the influence of external powers and moments. They come into existence when the volume of a material constantly changes its form as a consequence of mechanical, thermal, and/or chemical processes and is hindered by neighbouring volumes. Bodies with residual stress are in mechanical balance. These residual stresses can be manifested by means of all mechanical interventions disturbing this balance. Acoustical, optical, radiological, and magnetical methods involving material changes caused by residual stress can also serve for determining residual stress. Residual stresses have an ambivalent character. In technical practice, they are feared and liked at the same time. They cause trouble because they can be the cause for unexpected behaviour of construction elements. They are feared since they can cause failure, in the worst case with catastrophical consequences. They are appreciated, on the other hand, because, in many cases, they can contribute to improvements of the material behaviour under certain circumstances. But they are especially liked for their giving convenient and (this is most important) mostly uncontrollable explanations. For only in very few cases we have enough knowledge and possibilities for the objective evaluation of residual stresses. (orig.) [de

  11. Mutation of the regulatory phosphorylation site of tobacco nitrate reductase results in constitutive activation of the enzyme in vivo and nitrite accumulation.

    Science.gov (United States)

    Lillo, Cathrine; Lea, Unni S; Leydecker, Marie-Thérèse; Meyer, Christian

    2003-09-01

    In wild-type Nicotiana plumbaginifolia and other higher plants, nitrate reductase (NR) is rapidly inactivated/activated in response to dark/light transitions. Inactivation of NR is believed to be caused by phosphorylation at a special conserved regulatory Ser residue, Ser 521, and interactions with divalent cations and inhibitory 14-3-3 proteins. A transgenic N. plumbaginifolia line (S(521)) was constructed where the Ser 521 had been changed by site-directed mutagenesis into Asp. This mutation resulted in complete abolishment of inactivation in response to light/dark transitions or other treatments known to inactivate NR. During prolonged darkness, NR in wild-type plants is in the inactivated form, whereas NR in the S(521) line is always in the active form. Differences in degradation rate between NR from S(521) and lines with non-mutated NR were not found. Kinetic constants like Km values for NADH and NO3(-) were not changed, but a slightly different pH profile was observed for mutated NR as opposed to non-mutated NR. Under optimal growth conditions, the phenotype of the S(521) plants was not different from the wild type (WT). However, when plants were irrigated with high nitrate concentration, 150 mM, the transgenic plants accumulated nitrite in darkness, and young leaves showed chlorosis.

  12. Physiology and interaction of nitrate and nitrite reduction in Staphylococcus carnosus.

    OpenAIRE

    Neubauer, H; Götz, F

    1996-01-01

    Staphylococcus carnosus reduces nitrate to ammonia in two steps. (i) Nitrate was taken up and reduced to nitrite, and nitrite was subsequently excreted. (ii) After depletion of nitrate, the accumulated nitrite was imported and reduced to ammonia, which again accumulated in the medium. The localization, energy gain, and induction of the nitrate and nitrite reductases in S. carnosus were characterized. Nitrate reductase seems to be a membrane-bound enzyme involved in respiratory energy conserva...

  13. Nitrite ion mitigates the formation of N-nitrosodimethylamine (NDMA) during chloramination of ranitidine.

    Science.gov (United States)

    Seid, Mingizem Gashaw; Cho, Kangwoo; Lee, Changha; Park, Hyun-Mee; Hong, Seok Won

    2018-08-15

    Ranitidine (RNT) has been an important tertiary amine precursor of N-nitrosodimethylamine (NDMA) in chlorine-based water treatment, due to reaction with monochloramine (NH 2 Cl) with exceptionally high molar yields up to 90%. This study examined the effects of nitrite ions (NO 2 - ) on the kinetics of NDMA formation during the chloramination of RNT under variable concentrations of dissolved oxygen (DO, 0.7-7.5mg/L), RNT (5-30μM), NH 2 Cl (5-20mM), NO 2 - or NO 3 - (0-2mM) and pH (5.6-8.6). In the absence of the NO 2 - , the ultimate molar yield of NDMA after 6h of reaction was primarily influenced by [DO] and pH, while marginally affected by initial [RNT] and [NH 2 Cl]. A kinetic model, prepared in accordance with the reaction sequence of NDMA formation, suggested that the rate determining step was accelerated with increasing [NH 2 Cl] 0 , [DO], and pH. A Kinetic study together with ultra-performance liquid chromatography-quadrupole-time of flight mass spectrometer (UPLC-Q-TOF MS) and gas chromatography (GC)/TOF MS analyses in parallel demonstrated that the nitrite ion inhibited the nucleophilic substitution of the terminal amine on NH 2 Cl, and reduced the pseudo-steady state concentration of N-peroxyl radicals, significantly decreasing the ultimate yields of NDMA. Copyright © 2018 Elsevier B.V. All rights reserved.

  14. The redox interplay between nitrite and nitric oxide: From the gut to the brain

    Directory of Open Access Journals (Sweden)

    Cassilda Pereira

    2013-01-01

    We here discuss the implications of the redox conversion of nitrite to ·NO in the gut, how nitrite-derived ·NO may signal from the digestive to the central nervous system, influencing brain function, as well as a putative ascorbate-driven nitrite/NO pathway occurring in the brain.

  15. Neurotoxicity induced by alkyl nitrites: Impairment in learning/memory and motor coordination.

    Science.gov (United States)

    Cha, Hye Jin; Kim, Yun Ji; Jeon, Seo Young; Kim, Young-Hoon; Shin, Jisoon; Yun, Jaesuk; Han, Kyoungmoon; Park, Hye-Kyung; Kim, Hyung Soo

    2016-04-21

    Although alkyl nitrites are used as recreational drugs, there is only little research data regarding their effects on the central nervous system including their neurotoxicity. This study investigated the neurotoxicity of three representative alkyl nitrites (isobutyl nitrite, isoamyl nitrite, and butyl nitrite), and whether it affected learning/memory function and motor coordination in rodents. Morris water maze test was performed in mice after administrating the mice with varying doses of the substances in two different injection schedules of memory acquisition and memory retention. A rota-rod test was then performed in rats. All tested alkyl nitrites lowered the rodents' capacity for learning and memory, as assessed by both the acquisition and retention tests. The results of the rota-rod test showed that isobutyl nitrite in particular impaired motor coordination in chronically treated rats. The mice chronically injected with isoamyl nitrite also showed impaired function, while butyl nitrite had no significant effect. The results of the water maze test suggest that alkyl nitrites may impair learning and memory. Additionally, isoamyl nitrite affected the rodents' motor coordination ability. Collectively, our findings suggest that alkyl nitrites may induce neurotoxicity, especially on the aspect of learning and memory function. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  16. Stability of α-tocotrienol and α-tocopherol in salami-type sausages and curing brine depending on nitrite and pH.

    Science.gov (United States)

    Gerling, Eva-Maria; Ternes, Waldemar

    2014-12-01

    We studied the stability of the valuable vitamer nutrients α-tocotrienol and α-tocopherol and options for their protection in salami-type sausages (blended with α-tocotrienol-rich barley oil) and curing brine. Four different sausage formulations were produced containing nitrite curing salt; nitrite curing salt and ascorbic acid (300mg/kg); nitrite curing salt and carnosic acid (45mg/kg); or sodium chloride. Initial vitamer contents (100mg/kg) did not decrease significantly during ripening and decreased only slightly during storage. Ascorbic acid and carnosic acid were found to be effective in preserving the vitamers in fresh sausages. Freeze-drying of sausages resulted in a significant loss of vitamers (97%), particularly after 14-day storage at room temperature, even in the presence of shielding gases. The vitamer content in the curing brine decreased with decreasing pH in the presence of nitrite. A nitrite concentration of 136mg/L at pH4 resulted in significant loss (90%) of the vitamers. Sufficient stability of the vitamers in salami-type sausage and curing brine can be achieved by processing, formulation, and storage conditions. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Intramolecular electron transfer in Pseudomonas aeruginosa cd(1) nitrite reductase

    DEFF Research Database (Denmark)

    Farver, Ole; Brunori, Maurizio; Cutruzzolà, Francesca

    2009-01-01

    ) as the level of reduction increased in both the WT and the His mutant. Equilibrium standard enthalpy and entropy changes and activation parameters of this ET process were determined. We concluded that negative cooperativity is a common feature among the cd(1) nitrite reductases, and we discuss this control...

  18. Poppers: epidemiology and clinical management of inhaled nitrite abuse.

    Science.gov (United States)

    Romanelli, Frank; Smith, Kelly M; Thornton, Alice C; Pomeroy, Claire

    2004-01-01

    Commonly referred to as "poppers," inhaled nitrites have a long history of abuse. Poppers are rapid-onset, short-acting potent vasodilators that produce a rush characterized by warm sensations and feelings of dizziness. Poppers sometimes are used to facilitate anal intercourse because of their actions on the anal sphincter. Epidemiologically, the frequent use of nitrites by men who have sex with men has led some experts to implicate these chemicals in the pathogenesis of Kaposi's sarcoma and acquired immunodeficiency syndrome. Controlled clinical trials to examine this potential correlation have not been conducted, and the use of nitrites simply may be a marker for other high-risk behaviors such as unprotected sex. Although regulated in the United States, many nitrite compounds and isomers are sold at various venues including bars, bookstores, and over the Internet. Adverse effects associated with these products vary from mild allergic reactions to life-threatening methemoglobinemia. The potential for drug-drug interactions and a propensity toward unsafe sex also exist. Clinicians should be familiar with the populations most likely to abuse these agents and with the clinical effects and management guidelines for acute ingestions.

  19. Control of the ambident reactivity of the nitrite ion

    DEFF Research Database (Denmark)

    Dong, Hai; Rahm, Martin; Thota, Niranjan

    2013-01-01

    of this difference was addressed. The ambident reactivity of the nitrite ion has been found to be the cause of the complex product formation observed, which can be controlled by a neighbouring equatorial ester group. Both N-attack and O-attack occur in the absence of the ester group, whereas O-attack is favoured...

  20. Nutrient Concentrations in Upper and Lower Echo, Fallen Leaf, Spooner, and Marlette Lakes and Associated Outlet Streams, California and Nevada, 2002-03

    National Research Council Canada - National Science Library

    2004-01-01

    .... Water samples were collected to determine seasonal and spatial concentrations of dissolved nitrite plus nitrate, dissolved ammonia, total Kjeldahl nitrogen, dissolved orthophosphate, total phosphorus...

  1. Evaluation of the influence of proline, hydroxyproline or pyrrolidine in the presence of sodium nitrite on N-nitrosamine formation when heating cured meat.

    Science.gov (United States)

    Drabik-Markiewicz, G; Dejaegher, B; De Mey, E; Impens, S; Kowalska, T; Paelinck, H; Vander Heyden, Y

    2010-01-11

    N-nitrosamines are meant to be probable or possible carcinogenic components, possibly formed out of a reaction between nitrite and N-containing substances such as amino acids and secondary amines. Nitrite is often used for processing meat products because of its colouring and antimicrobial properties. During this experimental setup, the influence of proline, hydroxyproline or pyrrolidine on N-nitrosamine formation in meat samples was evaluated. The N-nitrosamines concentrations were measured with gas chromatography-thermal energy analyzer. Only the concentrations of N-nitrosodimethylamine and N-nitrosopyrrolidine were found above the limit of detection in a number of tested experimental conditions. The concentration of these two N-nitrosamines was modelled as a function of temperature and nitrite concentration for different situations (presence or absence of added natural N-containing meat components). It could be concluded that proline and pyrrolidine promoted the formation of N-nitrosopyrrolidine. It could also be confirmed that the higher the temperature of the meat processing procedure and the higher the sodium nitrite amounts added, the higher were the yields of the respective N-nitrosamines.

  2. Hole traps associated with high-concentration residual carriers in p-type GaAsN grown by chemical beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Elleuch, Omar, E-mail: mr.omar.elleuch@gmail.com; Wang, Li; Lee, Kan-Hua; Demizu, Koshiro; Ikeda, Kazuma; Kojima, Nobuaki; Ohshita, Yoshio; Yamaguchi, Masafumi [Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya 468-8511 (Japan)

    2015-01-28

    The hole traps associated with high background doping in p-type GaAsN grown by chemical beam epitaxy are studied based on the changes of carrier concentration, junction capacitance, and hole traps properties due to the annealing. The carrier concentration was increased dramatically with annealing time, based on capacitance–voltage (C–V) measurement. In addition, the temperature dependence of the junction capacitance (C–T) was increased rapidly two times. Such behavior is explained by the thermal ionization of two acceptor states. These acceptors are the main cause of high background doping in the film, since the estimated carrier concentration from C–T results explains the measured carrier concentration at room temperature using C–V method. The acceptor states became shallower after annealing, and hence their structures are thermally unstable. Deep level transient spectroscopy (DLTS) showed that the HC2 hole trap was composed of two signals, labeled HC21 and HC22. These defects correspond to the acceptor levels, as their energy levels obtained from DLTS are similar to those deduced from C–T. The capture cross sections of HC21 and HC22 are larger than those of single acceptors. In addition, their energy levels and capture cross sections change in the same way due to the annealing. This tendency suggests that HC21 and HC22 signals originate from the same defect which acts as a double acceptor.

  3. Hole traps associated with high-concentration residual carriers in p-type GaAsN grown by chemical beam epitaxy

    International Nuclear Information System (INIS)

    Elleuch, Omar; Wang, Li; Lee, Kan-Hua; Demizu, Koshiro; Ikeda, Kazuma; Kojima, Nobuaki; Ohshita, Yoshio; Yamaguchi, Masafumi

    2015-01-01

    The hole traps associated with high background doping in p-type GaAsN grown by chemical beam epitaxy are studied based on the changes of carrier concentration, junction capacitance, and hole traps properties due to the annealing. The carrier concentration was increased dramatically with annealing time, based on capacitance–voltage (C–V) measurement. In addition, the temperature dependence of the junction capacitance (C–T) was increased rapidly two times. Such behavior is explained by the thermal ionization of two acceptor states. These acceptors are the main cause of high background doping in the film, since the estimated carrier concentration from C–T results explains the measured carrier concentration at room temperature using C–V method. The acceptor states became shallower after annealing, and hence their structures are thermally unstable. Deep level transient spectroscopy (DLTS) showed that the HC2 hole trap was composed of two signals, labeled HC21 and HC22. These defects correspond to the acceptor levels, as their energy levels obtained from DLTS are similar to those deduced from C–T. The capture cross sections of HC21 and HC22 are larger than those of single acceptors. In addition, their energy levels and capture cross sections change in the same way due to the annealing. This tendency suggests that HC21 and HC22 signals originate from the same defect which acts as a double acceptor

  4. Nitrate denitrification with nitrite or nitrous oxide as intermediate products: Stoichiometry, kinetics and dynamics of stable isotope signatures.

    Science.gov (United States)

    Vavilin, V A; Rytov, S V

    2015-09-01

    A kinetic analysis of nitrate denitrification by a single or two species of denitrifying bacteria with glucose or ethanol as a carbon source and nitrite or nitrous oxide as intermediate products was performed using experimental data published earlier (Menyailo and Hungate, 2006; Vidal-Gavilan et al., 2013). Modified Monod kinetics was used in the dynamic biological model. The special equations were added to the common dynamic biological model to describe how isotopic fractionation between N species changes. In contrast to the generally assumed first-order kinetics, in this paper, the traditional Rayleigh equation describing stable nitrogen and oxygen isotope fractionation in nitrate was derived from the dynamic isotopic equations for any type of kinetics. In accordance with the model, in Vidal-Gavilan's experiments, the maximum specific rate of nitrate reduction was proved to be less for ethanol compared to glucose. Conversely, the maximum specific rate of nitrite reduction was proved to be much less for glucose compared to ethanol. Thus, the intermediate nitrite concentration was negligible for the ethanol experiment, while it was significant for the glucose experiment. In Menyailo's and Hungate's experiments, the low value of maximum specific rate of nitrous oxide reduction gives high intermediate value of nitrous oxide concentration. The model showed that the dynamics of nitrogen and oxygen isotope signatures are responding to the biological dynamics. Two microbial species instead of single denitrifying bacteria are proved to be more adequate to describe the total process of nitrate denitrification to dinitrogen. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Simultaneous GC-ECNICI-MS measurement of nitrite, nitrate and creatinine in human urine and plasma in clinical settings.

    Science.gov (United States)

    Hanff, Erik; Lützow, Moritz; Kayacelebi, Arslan Arinc; Finkel, Armin; Maassen, Mirja; Yanchev, Georgi Radoslavov; Haghikia, Arash; Bavendiek, Udo; Buck, Anna; Lücke, Thomas; Maassen, Norbert; Tsikas, Dimitrios

    2017-03-15

    Creatinine in urine is a useful biochemical parameter to correct the urinary excretion rate of endogenous and exogenous substances. Nitrite (ONO - ) and nitrate (ONO 2 - ) are metabolites of nitric oxide (NO), a signalling molecule with multiple biological functions. Under certain and standardized conditions, the concentration of nitrate in the urine is a suitable measure of whole body NO synthesis. The urinary nitrate-to-nitrite molar ratio (U NOx R) may indicate nitrite-dependent renal carbonic anhydrase (CA) activity. In clinical studies, urine is commonly collected by spontaneous micturition. In those cases the nitrate and nitrite excretion must be corrected for creatinine excretion. Pentafluorobenzyl (PFB) bromide (PFB-Br) is a useful derivatization reagent of numerous inorganic and organic compounds, including urinary nitrite, nitrate and creatinine, for highly sensitive and specific quantitation by GC-MS. Here, we report on the simultaneous PFB-Br derivatization (60min, 50°C) of ONO - , O 15 NO - , ONO 2 - , O 15 NO 2 - , creatinine (d o -Crea) and [methylo- 2 H 3 ]creatinine (d 3 -Crea) in acetonic dilutions of native human urine and plasma samples (4:1, v/v) and their simultaneous quantification by GC-MS as PFBNO 2 , PFB 15 NO 2 , PFBONO 2 , PFBO 15 NO 2 , d o -Crea-PFB and d 3 -Crea-PFB, respectively. Electron capture negative-ion chemical ionization (ECNICI) of these derivatives generates anions due to [M-PFB] - , i.e., the starting analytes. Quantification is performed by selected-ion monitoring (SIM) of m/z 46 (ONO - ), m/z 47 (O 15 NO - ), m/z 62 (ONO 2 - ), m/z 63 (O 15 NO 2 - ), m/z 112 (d o -Crea), and m/z 115 (d 3 -Crea). Retention times were 2.97min for PFB-ONO 2 /PFB-O 15 NO 2 , 3.1min for PFB-NO 2 /PFB- 15 NO 2 , and 6.7min for d o -Crea-PFB/d 3 -Crea-PFB. We used this method to investigate the effects of long-term oral NaNO 3 or NaCl (serving as placebo) supplementation (each 0.1mmol/kg body weight per day for 3 weeks) on creatinine excretion

  6. Evaluation of a method for determining concentrations of isoeugenol, an AQUI-S residue, in fillet tissue from freshwater fish species.

    Science.gov (United States)

    Meinertz, Jeffery R; Schreier, Theresa M; Bernardy, Jeffry A

    2008-01-01

    AQUI-S is a fish anesthetic/sedative that is approved for use in a number of countries throughout the world and has the potential for use in the United States. The active ingredient in AQUI-S is isoeugenol. A method for determining isoeugenol concentrations in edible fillet tissue is needed for regulatory purposes, including surveillance and potential use in studies fulfilling human food safety data requirements if U.S. Food and Drug Administration approval is pursued. A method was developed and evaluated for determining isoeugenol concentrations in fillet tissue using relatively common procedures and equipment. The method produced accurate and precise results with fillet tissue from 10 freshwater fish species. The percentage of isoeugenol recovered from samples fortified with isoeugenol at nominal concentrations of 1, 50, and 100 microg/g for all species was always >80 and fillet tissue containing biologically incurred isoeugenol was fillet tissue extracts from 9 of the 10 species. The method detection limits for all but one species ranged from 0.004 to 0.014 microg/g, and the quantitation limits ranged from 0.012 to 0.048 microg/g.

  7. Mechanism of anodic oxidation of molybdenum and tungsten in nitrate-nitrite melts

    International Nuclear Information System (INIS)

    Yurkinskij, V.P.; Firsova, E.G.; Morachevskij, A.G.

    1987-01-01

    The mechanism of anode oxidation of tungsten and molybdenum in NaNO 3 -KNO 3 (50 mass %) nitrate-nitrite melts with NaNO 2 -KNO 2 (0.5-50 mass %) addition and in NaNO 2 -KNO 2 (35 mole %) nitrite melt in the 516-580 K temperature range is studied. It is supposed that the process of anode dissloving of the mentioned metals in nitrite melt and nitrate-nitrite mixtures is two-electron. Formation of oxide passivating film is possible under electrolysis on the anode surface, the film is then dissolved in nitrate-nitrite melt with formation of molybdates or tungstates

  8. Composite of Cu metal nanoparticles-multiwall carbon nanotubes-reduced graphene oxide as a novel and high performance platform of the electrochemical sensor for simultaneous determination of nitrite and nitrate

    International Nuclear Information System (INIS)

    Bagheri, Hasan; Hajian, Ali; Rezaei, Mosayeb; Shirzadmehr, Ali

    2017-01-01

    Highlights: • An electrochemical sensor based on Cu metal nanoparticles-multiwall carbon nanotubes-reduced graphene oxide modified glassy carbon electrode was developed. • Simultaneous electrochemical determination of nitrate and nitrite by fabricated sensor was performed. • Modification improved the sensitivity and detection limit of the method. • It is a useful method for determining of nitrate and nitrite in various real samples. - Abstract: In the present research, we aimed to fabricate a novel electrochemical sensor based on Cu metal nanoparticles on the multiwall carbon nanotubes-reduced graphene oxide nanosheets (Cu/MWCNT/RGO) for individual and simultaneous determination of nitrite and nitrate ions. The morphology of the prepared nanocomposite on the surface of glassy carbon electrode (GCE) was characterized using various methods including scanning electron microscopy (SEM), atomic force microscopy (AFM), and electrochemical impedance spectroscopy. Under optimal experimental conditions, the modified GCE showed excellent catalytic activity toward the electro-reduction of nitrite and nitrate ions (pH = 3.0) with a significant increase in cathodic peak currents in comparison with the unmodified GCE. By square wave voltammetry (SWV) the fabricated sensor demonstrated wide dynamic concentration ranges from 0.1 to 75 μM with detection limits (3S_b/m) of 30 nM and 20 nM method for nitrite and nitrate ions, respectively. Furthermore, the applicability of the proposed modified electrode was demonstrated by measuring the concentration of nitrite and nitrate ions in the tap and mineral waters, sausages, salami, and cheese samples.

  9. Enriched Nitrate and Depleted Nitrite Isotopic Signatures in the OMZ off Northern Chile

    Science.gov (United States)

    Bristow, L. A.; Altabet, M. A.; Stewart, F.; Delong, E.; Ulloa, O.

    2010-12-01

    The vast majority of fixed nitrogen loss from the ocean’s water-column occurs in the O2 minimum zones of the Arabian Sea and the eastern tropical North and South Pacific (ETNP and ETSP). In these regions, subsurface O2 concentrations reach suboxic levels that favor microbial production of N2 gas from combined N sources via heterotrophic denitrification and anammox. One of the most intense oxygen minimum zones (OMZ) is found in the ETSP, especially off northern Chile, where O2 depleted waters can reach into the photic zone as a result of coastal upwelling and a narrow continental shelf. Despite the importance of these regions there still remains much uncertainty about N cycling in these regions. We present δ15N and δ18O isotope data for nitrate and δ15N data for nitrite, which along with corroborating relative gene abundances from metagenomes provide insight into N-cycling processes both within and above the OMZ. Depth profiles showed some of the highest δ15N nitrate values seen to date in an OMZ (up to 32‰), which has implications for tracing denitrification related biogeochemical signals throughout the Pacific and for downcore recording of past changes in OMZ intensity. Co-occurring nitrite δ15N in the OMZ fell in the range -6 to -20‰, resulting in a δ15N offset between co-occurring nitrate and nitrite in the range 30 to 40‰. This offset is greater than that expected from heterotrophic denitrification alone, implying either a larger isotope effect for the first enzymatic step in denitrification (NO3- reduction to NO2-) than previously estimated from field and culture studies or, more likely, that additional processes are enhancing this separation. NO3- consumption by heterotrophic denitrification has been shown to increase both δ15N and δ18O of nitrate in a 1:1 ratio. The slope for samples in the OMZ off northern Chile show a clear but surprisingly negative deviation from the expected slope of 1, again suggesting additional processes are occurring

  10. Solid residues

    International Nuclear Information System (INIS)

    Mulder, E.; Duin, P.J. van; Grootenboer, G.J.

    1995-01-01

    A summary is presented of the many investigations that have been done on solid residues of atmospheric fluid bed combustion (AFBC). These residues are bed ash, cyclone ash and bag filter ash. Physical and chemical properties are discussed and then the various uses of residues (in fillers, bricks, gravel, and for recovery of aluminium) are summarised. Toxicological properties of fly ash and stack ash are discussed as are risks of pneumoconiosis for workers handling fly ash, and contamination of water by ashes. On the basis of present information it is concluded that risks to public health from exposure to emissions of coal fly ash from AFBC appear small or negligible as are health risk to workers in the coal fly ash processing industry. 35 refs., 5 figs., 12 tabs

  11. Effects of vegetable juice powder concentration and storage time on some chemical and sensory quality attributes of uncured, emulsified cooked sausages.

    Science.gov (United States)

    Sindelar, J J; Cordray, J C; Sebranek, J G; Love, J A; Ahn, D U

    2007-06-01

    Uncured, no-nitrate/nitrite-added meat products can be manufactured with vegetable juice powder (VJP) and a starter culture containing Staphylococcus carnosus, resulting in quality and sensory attributes similar to traditional cured products. The 1st objective of this study was to determine the effects of varying concentrations of VJP and incubation times (MIN-HOLD) on quality characteristics, including lipid oxidation, color, and cured meat pigment concentrations, of emulsified-frankfurter-style-cooked (EFSC) sausages over a 90-d storage period. The 2nd objective was to compare residual nitrate and nitrite content resulting from different processing treatments and the 3rd objective was to assess sensory properties of finished products. Four EFSC sausage treatments (TRT) (TRT 1: 0.20% VJP, 30 MIN-HOLD; TRT 2: 0.20% VJP, 120 MIN-HOLD; TRT 3: 0.40% VJP, 30 MIN-HOLD; TRT 4: 0.40% VJP, 120 MIN-HOLD) and a sodium nitrite-added control (C) were used for this study. No differences for lipid oxidation (TBARS) between any TRTs and C or over time were observed. No differences (P > 0.05) for CIE L* values were found between TRTs. CIE a* and reflectance ratio values revealed that TRTs 2, 4, and C were redder than TRTs 1 and 3 at day 0. Trained sensory intensity ratings for cured aroma, cured color, cured flavor, uniform color, and firmness determined that all but TRT 1 were similar to C. These results indicate a longer incubation time (120 compared with 30 min) was found more critical than VJP level (0.20% or 0.40%) to result in products comparable to a sodium nitrite-added control.

  12. [Nitrates and nitrites content in the samples taken from the dug and drilled wells from the area of Podkarpacie region as a methemoglobinemia risk factors].

    Science.gov (United States)

    Bilek, Maciej; Rybakowa, Maria

    2014-01-01

    The aim of the study was to determine the nitrates and nitrites content in water samples taken from fourteen dug and drilled wells from the area of Podkarpacie, as well as a summary of the previously performed analysis. Private water intakes are not under the supervision of the State Sanitary Inspection. So in the case of exceeding the standards provided by the Regulation of the Minister of Health, regulating the requirements for drinking water, private water intakes can be a serious threat to the health of consumers. Particularly at risk are infants, in whom nitrates and especially nitrites can cause, among others, methemoglobinemia. The analysis was performed by ion chromatography method, making it possible to simultaneously determining the concentrations of nitrates and nitrites. As it turned out there was no presence of nitrites in the water of the tested wells. In five samples taken from the dug wells nitrates concentration exceeding the norm of 50 mg/L have been reported. In two cases, exceeding the nitrate concentrations were significant: 96.53 mg L and 204.65 mg/L.

  13. Retention and leaching of nitrite by municipal solid waste incinerator bottom ash under the landfill circumstance.

    Science.gov (United States)

    Yao, Jun; Kong, Qingna; Zhu, Huayue; Long, Yuyang; Shen, Dongsheng

    2015-01-01

    The retention and leaching of nitrite by municipal solid waste incinerator (MSWI) bottom ash could affect its migration in the landfill. In this study, the effect of the dosage of MSWI bottom ash as well as the variation of the landfill environmental parameters including pH, anions and organic matter on the nitrite retention and leaching behavior was investigated by batch experiments. The highest removal percentage (73.0%) of nitrite was observed when the dosage of MSWI bottom ash was 10 g L(-1) in 2 mg L(-1) nitrite solution. Further increase of the dosage would retard the retention, as the nitrite leaching from MSWI bottom ash was enhanced. The optimum retention of nitrite was observed when the pH was 5.0, while the leaching of nitrite showed a consistent reduction with the increase of pH. Besides, the presence of Cl(-), SO4(2)(-) and acetic acid could enhance the leaching of nitrite and mitigate the retention process. However, the retention of nitrite was enhanced by PO4(3)(-), which was probably due to the formation of the apatite, an active material for the adsorption of the nitrite. These results suggested that MSWI bottom ash could affect the migration of nitrite in the landfill, which was related to the variation of the landfill circumstance. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. The determination, by X-ray-fluorescence spectrometry, of tin and tungsten in ores, concentrates, and residues of scheelite, wolframite, and cassiterite

    International Nuclear Information System (INIS)

    Balaes, A.M.E.; Jacobs, J.J.; Bray, A.R.; Kendrick, K.

    1983-01-01

    The method of analysis described is applicable to samples with tin and tungsten contents from 15p.p.m. to 75 per cent. For samples containing tin and tungsten in the range 2000p.p.m. to 75 per cent, the matrix variations are compensated for by the use of briquettes containing coarse river sand, the internal standard, and potassium chloride, the last of which acts as a binder, diluet, and grinding aid. For the samples containing tin and tungsten in the range 15p.p.m. to 2000p.p.m., the potassium chloride is omitted. Zinc and antimony are used as the internal standard for tungsten and tin respectively. Calibration graphs for tin and tungsten are obtained by the use of standard reference materials for cassiterite and scheelite. The precision of the analysis for tin ranges from a relative standard deviation of 0,039 at 50p.p.m. to 0,005 at 75 per cent. The values for tungsten are relatively constant at between 0,015 and 0,008 at concentrations between 50p.p.m. and 50 per cent. The lower limits of detection for tungsten and tin by the high-concentration technique of analysis are 202 and 155p.p.m. respectively, and by the low-concentration technique the corresponding limits are 4 and 2p.p.m. The overall time required for the analysis of ten samples by these techniques is approximately 3 hours. The laboratory method is detailed in an appendix

  15. Integrated project: Microbiological and physiological studies on the presence of residual concentrations in mineral-oil-contaminated soils after rehabilitation. Final report. Pt. 2; Mikrobiologische und physiologische Untersuchungen zur Frage der Restkonzentration bei der Sanierung mineraloelkontaminierter Boeden. Abschlussbericht. T. 2

    Energy Technology Data Exchange (ETDEWEB)

    Miethe, D.; Riis, V.; Stimming, M.

    1996-01-04

    It has been known for a long time that microorganisms are able to utilise mineral oils. Today various methods are practised which exploit autochthonous microorganisms` ability to utilise mineral oils. The main problem of microbial decomposition of hydrocarbons is that mineral oil residues remain. The aim of the present research project was therefore to determine the limits of the metabolisability of the substrate and find out why residues remain. Mineral oils and residual fractions differ markedly in their decomposability. Intermediate distillates are easily decomposed to a degree of 95-97% by well-adapted consorts. For high-boiling mineral oils (bp>400 C) the degree of decomposition is approx. 60%. Extracts from contaminated sites range from 40 to 60% in their degree of decomposability. The incomplete microbial decomposition of mineral oils is mainly due to their structure. There remain chemically and thermally extremely, inert hydrocarbons (mainly aliphatic and aromatic fused-ring systems) which are either hardly metabolisable or not at all. An important factor in soils or at other contaminated sites is that some of the substrate is not available because it is bound to the matrix thus increasing the proportion of residue. The next task after examining and presenting the causes of incomplete decomposition is to minimise residual mineral oil concentrations remaining after microbial decomposition. Here the use of special surfactants or of auxiliary substrates could point a way. Project applications to this end have already been submitted to the Federal Ministry for Education and Research. (orig.) [Deutsch] Dass Mikroorganismen in der Lage sind, Mineraloele zu verwerten, ist seit langem bekannt. Verfahren, die das Potential autochthoner Mikroorganismen zur Verwertung von Mineraloelen nutzen sind Praxis. Hauptproblem beim mikrobiellen Abbau der Kohlenwasserstoffe ist das Verbleiben von Mineraloelresten. Das Ziel des Forschungsvorhabens war die Ermittlung der Grenzen

  16. Nitrite addition to acidified sludge significantly improves digestibility, toxic metal removal, dewaterability and pathogen reduction

    Science.gov (United States)

    Du, Fangzhou; Keller, Jürg; Yuan, Zhiguo; Batstone, Damien J.; Freguia, Stefano; Pikaar, Ilje

    2016-12-01

    Sludge management is a major issue for water utilities globally. Poor digestibility and dewaterability are the main factors determining the cost for sludge management, whereas pathogen and toxic metal concentrations limit beneficial reuse. In this study, the effects of low level nitrite addition to acidified sludge to simultaneously enhance digestibility, toxic metal removal, dewaterability and pathogen reduction were investigated. Waste activated sludge (WAS) from a full-scale waste water treatment plant was treated at pH 2 with 10 mg NO2--N/L for 5 h. Biochemical methane potential tests showed an increase in the methane production of 28%, corresponding to an improvement from 247 ± 8 L CH4/kg VS to 317 ± 1 L CH4/kg VS. The enhanced removal of toxic metals further increased the methane production by another 18% to 360 ± 6 L CH4/kg VS (a total increase of 46%). The solids content of dewatered sludge increased from 14.6 ± 1.4% in the control to 18.2 ± 0.8%. A 4-log reduction for both total coliforms and E. coli was achieved. Overall, this study highlights the potential of acidification with low level nitrite addition as an effective and simple method achieving multiple improvements in terms of sludge management.

  17. Nitrate/nitrite poisoning in dairy cattle from the Midwestern Minas Gerais, Brazil

    Directory of Open Access Journals (Sweden)

    Daniel Amaral Gontijo

    2017-11-01

    Full Text Available ABSTRACT: In a rural property of the Midwestern Minas Gerais, Brazil, three 2.5 to 3-year-old female bovines (7/8 Holstein x 1/8 Gir weighing approximately 380kg died after showing brownish colored mucosa of conjunctiva and vaginal vestibule, gray-bluish tongue, dyspnea, sialorrhea, tympany, and progression to sternal decubitus and death. In the macroscopic evaluation of one of the bovines, dark (chocolate-colored blood of difficult coagulation, and intensely cherry-red skeletal and cardiac musculature were observed. Beyond that were observed brownish lungs, kidneys, liver, and encephalon, and all the stomach compartments were dilated due to large amounts of gas. In addition, the carcass exhaled a nitrous odor. The diphenylamine test and the nitrate dosage in the forage (Pennisetum purpureum, “elephant grass”, Napier grass cultivar used in feeding the bovines showed a high concentration of nitrate, allowing the diagnosis of nitrate/nitrite intoxication. The main factors leading to the poisoning were attributed to excessive fertilization of grass with bovine manure, the occurrence of a drought period followed by a rainy season, lack of adaptation of the bovines to a nitrate-rich diet, and a diet composed almost exclusively of elephant grass. This is the first report of spontaneous nitrate/nitrite poisoning in cattle in southeastern Brazil.

  18. Antimicrobial activity of essential oils and fruits supplement in reduced nitrite salts condition

    Directory of Open Access Journals (Sweden)

    Vujadinović Dragan P.

    2017-01-01

    Full Text Available Because of the growing negative perception of consumers related to the use of meat products produced by conventional curing methods, organic and natural products are increasingly accepted by consumers. Such products contain a large number of natural products derived from plants, spices, as well as their derivatives in form of essential oils, extracts, concentrates, and so on. These derivatives contain large number of active substances which are known to inhibit the metabolic processes of bacteria, yeasts and molds. Therefore, the goal of this paper was to investigate the synergistic antimicrobial activity of the models with a reduced presence of nitrite salt in aqueous solution, emulsions of essential oils in varying concentrations in vivo via antibiogram tests on pathogenic microorganisms. The effect of the six model groups was analyzed. Two groups were fruit powder solutions in concentrations of 0.2% to 1.2% (Acerola powder and fruit powder mix, while the other four groups were models of aqueous emulsion of essential oil in concentrations ranging from 0.05% to 1.2% (tea tree, clove, oregano, and cinnamon essential oils. In all models reduced amount of the sodium salt of 1.80%, 0.0075% nitrite salt and the liquid derivative as a natural source of the nitrate salt of 3% were used. Antibiogram tests were performed on five pathogenic bacteria (C. perfringens, E. coli, S. enterica, L. monocytogenes, and S. aureus. All antibiogram tests were performed according to Kirby-Bauer disk diffusion protocol. Results of antibiograms showed that without the presence of additional antimicrobial agents, in model systems with reduced content of salts, inhibition zones were not detected. Additionally, models with essential oils of tea tree oil and oregano had the widest inhibition zone diameters, ranging from 17.76±0.48mm for E. coli up to 42.50±0.13mm for S. aureus.

  19. [Methemoglobinemia due to ingestion of isobutyl nitrite ('poppers')].

    Science.gov (United States)

    Pruijm, M T C; de Meijer, P H E M

    2002-12-07

    Two male students, aged 20 and 21 years, developed central cyanosis shortly after drinking 5 ml of 'poppers' (isobutyl nitrite). They presented with methaemoglobinaemia and were hospitalised. After treatment with oxygen and intravenous fluids they could be discharged in good health the following day. Poppers are alkyl nitrites with vasdilative and oxidizing properties. They are used as party drugs (i.e. inhaled) because of their short-lived euphoric effect. Overdose can result in methaemoglobinaemia: the presence of oxidized haemoglobin which is unable to transport oxygen. Depending on the serum level of methaemoglobin this may result in central cyanosis, unconsciousness, coma and even death. Patients with high methaemoglobin levels should be treated with i.v. methylene blue.

  20. Structural adaptations of octaheme nitrite reductases from haloalkaliphilic Thioalkalivibrio bacteria to alkaline pH and high salinity.

    Directory of Open Access Journals (Sweden)

    Anna Popinako

    Full Text Available Bacteria Tv. nitratireducens and Tv. paradoxus from soda lakes grow optimally in sodium carbonate/NaCl brines at pH range from 9.5 to 10 and salinity from 0.5 to 1.5 M Na+. Octaheme nitrite reductases (ONRs from haloalkaliphilic bacteria of genus Thioalkalivibrio are stable and active in a wide range of pH (up to 11 and salinity (up to 1 M NaCl. To establish adaptation mechanisms of ONRs from haloalkaliphilic bacteria a comparative analysis of amino acid sequences and structures of ONRs from haloalkaliphilic bacteria and their homologues from non-halophilic neutrophilic bacteria was performed. The following adaptation strategies were observed: (1 strategies specific for halophilic and alkaliphilic proteins (an increase in the number of aspartate and glutamate residues and a decrease in the number of lysine residues on the protein surface, (2 strategies specific for halophilic proteins (an increase in the arginine content and a decrease in the number of hydrophobic residues on the solvent-accessible protein surface, (3 strategies specific for alkaliphilic proteins (an increase in the area of intersubunit hydrophobic contacts. Unique adaptation mechanism inherent in the ONRs from bacteria of genus Thioalkalivibrio was revealed (an increase in the core in the number of tryptophan and phenylalanine residues, and an increase in the number of small side chain residues, such as alanine and valine, in the core.

  1. Determination of nitrate, nitrite, N- nitrosamines, cyanide and ...

    African Journals Online (AJOL)

    The nitrate, nitrite, N- nitrosamines and ascorbic acid content as well as the levels of cyanide in eight brands of fruit juices and twelve brands of sachet water commonly marketed and consumed in Nigeria were estimated. The mean values of nitrate ranged from 2.29±0.05 to 16.50±1.21 mg/L for the juices and 0.64±0.21 to ...

  2. The negative phonon confinement effect in nanoscopic sodium nitrite

    Czech Academy of Sciences Publication Activity Database

    Koroleva, E.Yu.; Nuzhnyy, Dmitry; Pokorný, Jan; Kamba, Stanislav; Kumzerov, Y. A.; Vakhrushev, S. B.; Petzelt, Jan

    2009-01-01

    Roč. 20, č. 39 (2009), 395706/1-395706/7 ISSN 0957-4484 R&D Projects: GA AV ČR KJB100100704; GA ČR(CZ) GA202/09/0682 Institutional research plan: CEZ:AV0Z10100520 Keywords : nanocomposite * sodium nitrite * infrared * THz * Raman * phonon * effective medium approach Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.137, year: 2009

  3. Nitrate ammonification in mangrove soils: a hidden source of nitrite?

    KAUST Repository

    Balk, Melike; Laverman, Anniet M; Keuskamp, Joost A; Laanbroek, Hendrikus J

    2015-01-01

    Nitrate reduction is considered to be a minor microbial pathway in the oxidation of mangrove-derived organic matter due to a limited supply of nitrate in mangrove soils. At a limited availability of this electron acceptor compared to the supply of degradable carbon, nitrate ammonification is thought to be the preferential pathway of nitrate reduction. Mangrove forest mutually differ in their productivity, which may lead to different available carbon to nitrate ratios in their soil. Hence, nitrate ammonification is expected to be of more importance in high- compared to low-productive forests. The hypothesis was tested in flow-through reactors that contain undisturbed mangrove soils from high-productive Avicennia germinans and Rhizophora mangle forests in Florida and low-productive Avicennia marina forests in Saudi Arabia. Nitrate was undetectable in the soils from both regions. It was assumed that a legacy of nitrate ammonification would be reflected by a higher ammonium production from these soils upon the addition of nitrate. Unexpectedly, the soils from the low-productive forests in Saudi Arabia produced considerably more ammonium than the soils from the high-productive forests in Florida. Hence, other environmental factors than productivity must govern the selection of nitrate ammonification or denitrification. A rather intriguing observation was the 1:1 production of nitrite and ammonium during the consumption of nitrate, more or less independent from sampling region, location, sampling depth, mangrove species and from the absence or presence of additional degradable carbon. This 1:1 ratio points to a coupled production of ammonium and nitrite by one group of nitrate-reducing microorganisms. Such a production of nitrite will be hidden by the presence of active nitrite-reducing microorganisms under the nitrate-limited conditions of most mangrove forest soils.

  4. Nitrate ammonification in mangrove soils: a hidden source of nitrite?

    KAUST Repository

    Balk, Melike

    2015-03-02

    Nitrate reduction is considered to be a minor microbial pathway in the oxidation of mangrove-derived organic matter due to a limited supply of nitrate in mangrove soils. At a limited availability of this electron acceptor compared to the supply of degradable carbon, nitrate ammonification is thought to be the preferential pathway of nitrate reduction. Mangrove forest mutually differ in their productivity, which may lead to different available carbon to nitrate ratios in their soil. Hence, nitrate ammonification is expected to be of more importance in high- compared to low-productive forests. The hypothesis was tested in flow-through reactors that contain undisturbed mangrove soils from high-productive Avicennia germinans and Rhizophora mangle forests in Florida and low-productive Avicennia marina forests in Saudi Arabia. Nitrate was undetectable in the soils from both regions. It was assumed that a legacy of nitrate ammonification would be reflected by a higher ammonium production from these soils upon the addition of nitrate. Unexpectedly, the soils from the low-productive forests in Saudi Arabia produced considerably more ammonium than the soils from the high-productive forests in Florida. Hence, other environmental factors than productivity must govern the selection of nitrate ammonification or denitrification. A rather intriguing observation was the 1:1 production of nitrite and ammonium during the consumption of nitrate, more or less independent from sampling region, location, sampling depth, mangrove species and from the absence or presence of additional degradable carbon. This 1:1 ratio points to a coupled production of ammonium and nitrite by one group of nitrate-reducing microorganisms. Such a production of nitrite will be hidden by the presence of active nitrite-reducing microorganisms under the nitrate-limited conditions of most mangrove forest soils.

  5. Glocal assessment of integrated wastewater treatment and recovery concepts using partial nitritation/Anammox and microalgae for environmental impacts.

    Science.gov (United States)

    Khiewwijit, Rungnapha; Rijnaarts, Huub; Temmink, Hardy; Keesman, Karel J

    2018-07-01

    This study explored the feasibility and estimated the environmental impacts of two novel wastewater treatment configurations. Both include combined bioflocculation and anaerobic digestion but apply different nutrient removal technologies, i.e. partial nitritation/Anammox or microalgae treatment. The feasibility of such configurations was investigated for 16 locations worldwide with respect to environmental impacts, such as net energy yield, nutrient recovery and effluent quality, CO 2 emission, and area requirements. The results quantitatively support the applicability of partial nitritation/Anammox in tropical regions and some locations in temperate regions, whereas microalgae treatment is only applicable the whole year round in tropical regions that are close to the equator line. Microalgae treatment has an advantage over the configuration with partial nitritation/Anammox with respect to aeration energy and nutrient recovery, but not with area requirements. Differential sensitivity analysis points out the dominant influence of microalgal biomass yield and wastewater nutrient concentrations on area requirements and effluent quality. This study provides initial selection criteria for worldwide feasibility and corresponding environmental impacts of these novel municipal wastewater treatment plant configurations. Copyright © 2018. Published by Elsevier B.V.

  6. Nitrate and nitrite contamination of sub-surface water in some areas of North West Frontier Province (N.W.F.P.) Pakistan

    International Nuclear Information System (INIS)

    Khan, M.; Khawaja, M.A.; Imdadullah

    1998-01-01

    Over the past few years, nitrate and nitrite contamination of sub-surface water samples from Peshawar, Charsada, Mardan and Nowshera districts of NWFP has been studied. In all the areas under study, nitrate concentration of sub-surface water was found to be below WHO approved limit of 45 mg/l. Whereas city area after 1987 showed a decreasing level of nitrate contamination of sub-surface water, it appeared to be on the increase in water samples from the outskirts of Peshawar-Charsada road. No uniform increasing or decreasing patterns of nitrate contamination were observed for water samples from cantonment, University and Hayatabad, areas of Mardan, Charsada and Nowshera under study. The nitrate contamination of sub-surface water appeared to be due to both the agricultural activities as well as human and animal wastes. A few sub-surface water samples from Peshawar city, Mardan and Nowshera areas indicated high concentration of nitrite, which is alarming in view of the earlier reports showing absence of nitrite in water samples from these areas. However, since 1993, nitrite presence has not been detected in sub-surface water samples from all the areas under present investigation. (author)

  7. Simultaneous high-performance liquid chromatographic determination of nitrate, nitrite, and organic pesticides in soil solution using a multidimensional column with ultraviolet detection

    International Nuclear Information System (INIS)

    Nkedi-Kizza, P.; Owusu-Yaw, J.

    1992-01-01

    In many fertilizer trials, the amount of nitrate-nitrogen in soil solution must be quantified frequently because nitrate is easily leached. Because pesticides are generally applied to cropland with fertilizers, quantitative information is needed on the concentration of these chemicals still available in the soil. Information on nitrite, nitrate and pesticide concentrations in food, water and environmental samples is essential because of their toxicity and potential for groundwater and surface water contamination. Most of the methods currently used for nitrate determination also account for nitrite, because nitrite and some organics act as interferences. Some of the existing analytical methods require sample reduction or derivatization, complex solvent mixtures or large sample volumes which make analysis times long. A High-Performance Liquid Chromatography (HPLC) method has been developed for the simultaneous determination of nitrate, nitrite and organic pesticides in soil solution samples and extracts using a multidimensional separator column with ultraviolet detection at 220 nm. The method is rapid and requires small sample volumes (20 μL). It is a sensitive method which is suitable for routine analyses of up to 100 samples per day. A comparison of this method with standard ion chromatography with conductivity detection showed very good agreement between the two methods for the analysis of NO3- and NO2-

  8. Reduction of nitrogen oxides by gamma-irradiated hemoproteins. Pt. 1. Nitrite reducing activity of gamma-irradiated hemoproteins

    Energy Technology Data Exchange (ETDEWEB)

    Oku, Tadatake; Kondo, Mitutaka; Sato, Hitoshi; Ichikawa, Yoshinobu; Nishio, Toshiyuki; Ito, Teiichiro [Nihon Univ., Tokyo (Japan). Coll. of Agriculture and Veterinary Medicine

    1994-08-01

    In nature, nitrite reductases located in microorganisms as well as in plants convert nitrite (NO{sub 2}{sup -}) into ammonium ion (NH{sub 4}{sup +}). It is rather difficult to isolate nitrite reductase because of very low content in microorganisms and plants. Bovine blood hemoglobin (Hb), horse cardiac muscle myoglobin (Mb) and horse cardiac muscle cytochrome c (Cyt c) in 50{mu}M aqueous solution were treated by gamma-irradiation at doses of 10-30 kGy in the presence of air. The present study shows that NO{sub 2}{sup -} is connected into NH{sub 4}{sup +} by gamma-irradiated hemoprotein in the presence of sodium hydrosulfite as a reducing agent and methyl viologen as an electron carrier. The concentration of NO{sub 2}{sup -} and NH{sub 4}{sup +} after reaction were determined by using diazo-reaction and ninhydrin reaction, respectively, after separation by HPLC. NO{sub 2}{sup -} remained and NH{sub 4}{sup +} formed by 10 kGy irradiated Cyt c, Hb and Mb at pH4 at 60 min were, 0% and 46%, 17% and 31%, 31% and 24%, respectively. Formation of hydroxylamine by reaction of NO{sub 2}{sup -} was not recognized in this reaction. The process of conversion of NO{sub 2}{sup -} to NH{sub 4}{sup +} is a net 6 electrons, 8-proton reaction. These results suggest that gamma-irradiated Hb, Mb and Cyt c can be used as a substituent of nitrite reductase. (J.P.N.).

  9. Changes in plasma and urinary nitrite after birth in premature infants at risk for necrotizing enterocolitis

    Science.gov (United States)

    Pun, Priti; Jones, Jesica; Wolfe, Craig; Deming, Douglas D.; Power, Gordon G.; Blood, Arlin B.

    2016-01-01

    Background Plasma nitrite serves as a reservoir of nitric oxide (NO) bioactivity. Because nitrite ingestion is markedly lower in newborns than adults, we hypothesized plasma nitrite levels would be lower in newborns than in adults, and that infants diagnosed with necrotizing enterocolitis (NEC), a disease characterized by ischemia and bacterial invasion of intestinal walls, would have lower levels of circulating nitrite in the days prior to diagnosis. Methods Single blood and urine samples were collected from 9 term infants and 12 adults, 72 preterm infants every 5 d for 3 wk, and from 13 lambs before and after cord occlusion. Results Nitrite fell 50% relative to cord levels in the first day after birth; and within 15 min after cord occlusion in lambs. Urinary nitrite was higher in infants than adults. Plasma and urinary nitrite levels in infants who developed NEC were similar to those of preterm control infants on days 1 and 5, but significantly elevated at 15 and 20 d after birth. Conclusion Plasma nitrite falls dramatically at birth while newborn urinary nitrite levels are significantly greater than adults. Acute NEC is associated with elevated plasma and urinary nitrite levels. PMID:26539663

  10. Nitrite reductase activity and inhibition of H₂S biogenesis by human cystathionine ß-synthase.

    Directory of Open Access Journals (Sweden)

    Carmen Gherasim

    Full Text Available Nitrite was recognized as a potent vasodilator >130 years and has more recently emerged as an endogenous signaling molecule and modulator of gene expression. Understanding the molecular mechanisms that regulate nitrite metabolism is essential for its use as a potential diagnostic marker as well as therapeutic agent for cardiovascular diseases. In this study, we have identified human cystathionine ß-synthase (CBS as a new player in nitrite reduction with implications for the nitrite-dependent control of H₂S production. This novel activity of CBS exploits the catalytic property of its unusual heme cofactor to reduce nitrite and generate NO. Evidence for the possible physiological relevance of this reaction is provided by the formation of ferrous-nitrosyl (Fe(II-NO CBS in the presence of NADPH, the human diflavin methionine synthase reductase (MSR and nitrite. Formation of Fe(II-NO CBS via its nitrite reductase activity inhibits CBS, providing an avenue for regulating biogenesis of H₂S and cysteine, the limiting reagent for synthesis of glutathione, a major antioxidant. Our results also suggest a possible role for CBS in intracellular NO biogenesis particularly under hypoxic conditions. The participation of a regulatory heme cofactor in CBS in nitrite reduction is unexpected and expands the repertoire of proteins that can liberate NO from the intracellular nitrite pool. Our results reveal a potential molecular mechanism for cross-talk between nitrite, NO and H₂S biology.

  11. Expression, purification, crystallization and preliminary X-ray diffraction analysis of the soluble domain of PPA0092, a putative nitrite reductase from Propionibacterium acnes

    International Nuclear Information System (INIS)

    Nojiri, Masaki; Shirota, Felicia; Hira, Daisuke; Suzuki, Shinnichiro

    2009-01-01

    The soluble domain of a putative copper-containing nitrite reductase from P. acnes has been overexpressed, purified and crystallized. The crystal belonged to space group P2 1 3 and diffracted to 2.4 Å resolution. The soluble domain (residues 483–913) of PPA0092, a putative copper-containing nitrite reductase from Propionibacterium acnes KPA171202, has been overexpressed in Escherichia coli. The purified recombinant protein was crystallized using the hanging-drop vapour-diffusion method. X-ray diffraction data were collected and processed to a maximum resolution of 2.4 Å. The crystal belonged to space group P2 1 3, with unit-cell parameters a = b = c = 108.63 Å. Preliminary diffraction data show that one molecule is present in the asymmetric unit; this corresponds to a V M of 2.1 Å 3 Da −1

  12. Presence, concentrations and risk assessment of selected antibiotic residues in sediments and near-bottom waters collected from the Polish coastal zone in the southern Baltic Sea - Summary of 3years of studies.

    Science.gov (United States)

    Siedlewicz, Grzegorz; Białk-Bielińska, Anna; Borecka, Marta; Winogradow, Aleksandra; Stepnowski, Piotr; Pazdro, Ksenia

    2018-04-01

    Concentrations of selected antibiotic compounds from different groups were measured in sediment samples (14 analytes) and in near-bottom water samples (12 analytes) collected in 2011-2013 from the southern Baltic Sea (Polish coastal zone). Antibiotics were determined at concentration levels of a few to hundreds of ng g -1 d.w. in sediments and ng L -1 in near-bottom waters. The most frequently detected compounds were sulfamethoxazole, trimethoprim, oxytetracycline in sediments and sulfamethoxazole and trimethoprim in near-bottom waters. The occurrence of the identified antibiotics was characterized by spatial and temporal variability. A statistically important correlation was observed between sediment organic matter content and the concentrations of sulfachloropyridazine and oxytetracycline. Risk assessment analyses revealed a potential high risk of sulfamethoxazole contamination in near-bottom waters and of contamination by sulfamethoxazole, trimethoprim and tetracyclines in sediments. Both chemical and risk assessment analyses show that the coastal area of the southern Baltic Sea is highly exposed to antibiotic residues. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Residual basins

    International Nuclear Information System (INIS)

    D'Elboux, C.V.; Paiva, I.B.

    1980-01-01

    Exploration for uranium carried out over a major portion of the Rio Grande do Sul Shield has revealed a number of small residual basins developed along glacially eroded channels of pre-Permian age. Mineralization of uranium occurs in two distinct sedimentary units. The lower unit consists of rhythmites overlain by a sequence of black shales, siltstones and coal seams, while the upper one is dominated by sandstones of probable fluvial origin. (Author) [pt

  14. The processing of simulated high-level radioactive waste sludges containing nitrites and mercury

    International Nuclear Information System (INIS)

    Zamecnik, J.R.; Hutson, N.D.; Ritter, J.A.; Carter, J.T.

    1991-01-01

    The reaction of formic acid with simulated alkaline sludge containing mercury and nitrite was studied in an engineering-scale facility. Quantification of offgas production was performed, with the major offgases being CO 2 and NO x . A small amount of CO was also found. The NO x was scrubbed in the offgas condenser and formed very acidic solutions of nitrous and nitric acids. These acids dissolved mercury that was stripped from the sludge. However, the overall efficiency of mercury stripping was greater than expected, and the final mercury concentration in the sludge was lower than expected. The NO x in the offgas also caused large temperature rises in the offgas system due to the exothermic reaction of NO with O 2 . This temperature rise had a detrimental effect on the performance of the Formic Acid Vent Condenser, such that redesign is being contemplated. 6 refs., 6 figs., 3 tabs

  15. Effect of Nitrite Ions on Steel Corrosion Induced by Chloride or Sulfate Ions

    Directory of Open Access Journals (Sweden)

    Zhonglu Cao

    2013-01-01

    Full Text Available The influence of nitrite concentration on the corrosion of steel immersed in three simulated pH environments containing chloride ions or sulfate ions has been investigated by comparing and analyzing the change of half-cell potential, the change of threshold level of Cl- or SO42-, the change of threshold level of NO2-/Cl- or NO2-/SO42- mole ratio, and the changes of anodic/cathodic polarization curves and Stern-Geary constant B. The corrosivity of chloride ions against sulfate ions also has been discussed in pH 12.6, pH 10.3, and pH 8.1 environments containing 0, 0.053, and 0.2 mol/L NO2, respectively.

  16. Nitrites and nitrates in the human diet: Carcinogens or beneficial hypotensive agents?

    Science.gov (United States)

    Butler, Anthony

    2015-06-05

    The presence of nitrite in the human diet was thought to constitute a hazard as secondary nitrosamines are known to cause gastric cancers. Recent publications on the physiology of serum nitrite have been consulted. Nitrite is added to some foodstuffs as an antibotulinum agent. The epidemiological evidence that nitrite causes gastric ulcers is weak. On the other hand, evidence that the presence of nitrite in serum lowers blood pressure is strong. This allows us to explain why a Tang dynasty treatment for angina, given in a Dunhuang medical manuscript, can be successful. The presence of nitrite in food is free of danger and a diet high in nitrate is beneficial to the health. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  17. Nitrite and Nitrate Content in Meat Products and Estimated Intake in Denmark From 1998 to 2006

    DEFF Research Database (Denmark)

    Leth, Torben; Fagt, Sisse; Nielsen, S.

    2008-01-01

    The content of nitrite and nitrate in cured meat products has been monitored in Denmark seven times between 1995 and 2006. The maximum permitted added amounts of sodium nitrite in Denmark (60 mg kg(-1) for most products up to 150 mg kg(-1) for special products) have not been exceeded, except...... period with levels varying between 6 and 20 mg sodium nitrite kg(-1) with sausages, meat for open sandwiches and salami-type sausages being the greatest contributors. The mean intake of sodium nitrate was around 1 mg day(-1), which is very low compared with the total intake of 61 mg day(-1). The mean...... group, only very few persons were responsible for the high intake. The conversion of nitrate to nitrite in the saliva and the degradation of nitrite during production and storage must also be considered when evaluating the intake of nitrite....

  18. Enhancing nitrite inhibition of Clostridium botulinum with isoascorbate in perishable canned cured meat.

    Science.gov (United States)

    Tompkin, R B; Christiansen, L N; Shaparis, A B

    1978-01-01

    Addition of sodium isoascorbate to the formulation for perishable canned comminuted cured meat markedly enhanced the efficacy of nitrite against Clostridium botulinum. This effect was reproducible through a series of three tests. In one test it was found that the initial addition of 50 microgram of sodium nitrite per g plus isoascorbate was as effective as 156 microgram of sodium nitrite per g alone. PMID:341810

  19. A new method for the determination of the nitrogen content of nitrocellulose based on the molar ratio of nitrite-to-nitrate ions released after alkaline hydrolysis

    International Nuclear Information System (INIS)

    Alinat, Elodie; Delaunay, Nathalie; Archer, Xavier; Mallet, Jean-Maurice; Gareil, Pierre

    2015-01-01

    Highlights: • New insights into the nitrocellulose alkaline denitration mechanism. • Linear correlation for molar ratio of nitrite-to-nitrate ions and nitrogen content. • Capillary electrophoresis monitoring of nitrite and nitrate ions. • Applications to explosive and non-explosive nitrocellulose-containing samples. • Improved performances (including safety) over classical methods. - Abstract: A new method was proposed to determine the nitrogen content of nitrocelluloses (NCs). It is based on the finding of a linear relationship between the nitrogen content and the molar ratio of nitrite-to-nitrate ions released after alkaline hydrolysis. Capillary electrophoresis was used to monitor the concentration of nitrite and nitrate ions. The influences of hydrolysis time and molar mass of NC on the molar ratio of nitrite-to-nitrate ions were investigated, and new insights into the understanding of the alkaline denitration mechanism of NCs, underlying this analytical strategy is provided. The method was then tested successfully with various explosive and non-explosive NC-containing samples such as various daily products and smokeless gunpowders. Inherently to its principle exploiting a concentration ratio, this method shows very good repeatability in the determination of nitrogen content in real samples with relative standard deviation (n = 3) inferior to 1.5%, and also provides very significant advantages with respect to sample extraction, analysis time (1 h for alkaline hydrolysis, 3 min for electrophoretic separation), which was about 5 times shorter than for the classical Devarda's method, currently used in industry, and safety conditions (no need for preliminary drying NC samples, mild hydrolysis conditions with 1 M sodium hydroxide for 1 h at 60 °C)

  20. A new method for the determination of the nitrogen content of nitrocellulose based on the molar ratio of nitrite-to-nitrate ions released after alkaline hydrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Alinat, Elodie, E-mail: elodie.alinat@chimie-paristech.fr [PSL Research University, Chimie ParisTech, Laboratory of Physicochemistry of Electrolytes, Colloids and Analytical Sciences (PECSA), 11 rue Pierre et Marie Curie, 75005 Paris (France); Central Laboratory of Police Prefecture (LCPP), 39 bis rue de Dantzig, 75015 Paris (France); CNRS, UMR 7195 PECSA, 11 rue Pierre et Marie Curie, 75005 Paris (France); Sorbonne Universités, UPMC Univ Paris 06, LBM, 4 place Jussieu, F-75005 Paris (France); Delaunay, Nathalie, E-mail: nathalie.delaunay@espci.fr [PSL Research University, Chimie ParisTech, Laboratory of Physicochemistry of Electrolytes, Colloids and Analytical Sciences (PECSA), 11 rue Pierre et Marie Curie, 75005 Paris (France); CNRS, UMR 7195 PECSA, 11 rue Pierre et Marie Curie, 75005 Paris (France); Sorbonne Universités, UPMC Univ Paris 06, LBM, 4 place Jussieu, F-75005 Paris (France); Archer, Xavier, E-mail: xavier.archer@interieur.gouv.fr [Central Laboratory of Police Prefecture (LCPP), 39 bis rue de Dantzig, 75015 Paris (France); Mallet, Jean-Maurice, E-mail: jean-maurice.mallet@es.fr [École Normale Supérieure-PSL Research University, Département de Chimie, 24 rue Lhomond, 75005 Paris (France); Sorbonne Universités, UPMC Univ Paris 06, LBM, 4 place Jussieu, F-75005 Paris (France); CNRS, UMR 7203 LBM, F-75005 Paris (France); Gareil, Pierre, E-mail: pierre.gareil@chimie-paristech.fr [PSL Research University, Chimie ParisTech, Laboratory of Physicochemistry of Electrolytes, Colloids and Analytical Sciences (PECSA), 11 rue Pierre et Marie Curie, 75005 Paris (France); CNRS, UMR 7195 PECSA, 11 rue Pierre et Marie Curie, 75005 Paris (France); Sorbonne Universités, UPMC Univ Paris 06, LBM, 4 place Jussieu, F-75005 Paris (France)

    2015-04-09

    Highlights: • New insights into the nitrocellulose alkaline denitration mechanism. • Linear correlation for molar ratio of nitrite-to-nitrate ions and nitrogen content. • Capillary electrophoresis monitoring of nitrite and nitrate ions. • Applications to explosive and non-explosive nitrocellulose-containing samples. • Improved performances (including safety) over classical methods. - Abstract: A new method was proposed to determine the nitrogen content of nitrocelluloses (NCs). It is based on the finding of a linear relationship between the nitrogen content and the molar ratio of nitrite-to-nitrate ions released after alkaline hydrolysis. Capillary electrophoresis was used to monitor the concentration of nitrite and nitrate ions. The influences of hydrolysis time and molar mass of NC on the molar ratio of nitrite-to-nitrate ions were investigated, and new insights into the understanding of the alkaline denitration mechanism of NCs, underlying this analytical strategy is provided. The method was then tested successfully with various explosive and non-explosive NC-containing samples such as various daily products and smokeless gunpowders. Inherently to its principle exploiting a concentration ratio, this method shows very good repeatability in the determination of nitrogen content in real samples with relative standard deviation (n = 3) inferior to 1.5%, and also provides very significant advantages with respect to sample extraction, analysis time (1 h for alkaline hydrolysis, 3 min for electrophoretic separation), which was about 5 times shorter than for the classical Devarda's method, currently used in industry, and safety conditions (no need for preliminary drying NC samples, mild hydrolysis conditions with 1 M sodium hydroxide for 1 h at 60 °C)

  1. Radiation preservation with reduced nitrites of bacon and other cured meats - a review

    International Nuclear Information System (INIS)

    Singh, H.

    1987-01-01

    The main problem caused by nitrite as a preservative is the formation of carcinogenic nitrosamines in bacon and other cured meats. This has led to a search for alternatives to the use of nitrite. Irradiation with reduced level of nitrite is a promising alternative to the use of current levels of nitrite. Radurization (radiation pasteurization) of bacon containing 20 to to 40 mg/kg of nitrite in evacuated packages, irradiated and stored at 4 degrees C, gives a product with good organoleptic qualities and extended shelf life of > 80 days vs. < days 30 days for the conventionally treated bacon. Radappertization (radiation sterilization) of bacon containing 20 mg/kg of nitrite at a dose of about 30 kGy, irradiated at -20 degrees or lower in evacuated packages, results in a product that is shelf stable for months to years at room temperature (∼ 25 degrees C). It has organoleptic properties comparable to commercial bacon in terms of color, flavor, odor and texture. Irradiation also reduces the nitrite and preformed nitrosamines present in bacon. Lower levels of nitrosamines are formed on cooking irradiated bacon containing presently used commercial levels of nitrite (120-150 mg/kg) and the levels of nitrosamines become negligible with 20 mg/kg of nitrite. Various aspects of preservation of bacon and other cured meats are reviewed in this report with emphasis on radiation processing. 357 refs

  2. Low nitrous oxide production in intermittent-feed high performance nitritating reactors

    DEFF Research Database (Denmark)

    Su, Qingxian; Jensen, Malene M.; Smets, Barth F.

    Nitrous oxide (N2O) production from autotrophic nitrogen removal processes, especially nitritating systems, is of growing concern. N2O dynamics were characterized and N2O production factors were quantified in two lab-scale intermittent-feed nitritating SBRs. 93 ± 14% of the oxidized ammonium...... was converted to nitrite, with the average total net N2O production of 2.1 ± 0.7% of the ammonium oxidized. Operation with intermittent feeding appears an effective optimization approach to mitigate N2O emissions from nitritating systems. Net N2O production rates transiently increased with a rise in pH after...

  3. Can urinary nitrite results be used to conduct antimicrobial option for urinary tract infection in children?

    Science.gov (United States)

    Mahyar, Abolfazl; Ayazi, Parviz; Froozesh, Mahta; Daneshi-Kohan, Mohammad-Mahdi; Barikani, Ameneh

    2012-06-01

    This study was performed to determine the relationship between urinary nitrite results and bacterial resistance to antimicrobial drugs in urinary tract infection of children. In a cross-section study 119 children younger than 12 years with urinary tract infection were evaluated in Qazvin children's hospital. Patients were divided into negative and positive nitrite groups depending on urinary nitrite test result. Rates of antibiotic resistance in the two groups were compared. Sixty seven patients were in the negative nitrite group and 52 in the positive nitrite group. Resistance rates to ceftriaxone, trimethoprim sulfamethoxazole, ampicillin, gentamicin, amikacin, nalidixic acid, cephalothin and nitrofurantoin in the nitrite negative group were 7.5%, 31.3%, 50.7%, 11.9%, 9%, 3%, 14.9% and 11.9%, respectively. These values in the nitrite positive group were 21.2%, 28.8%, 63.5%, 7.7%, 5.8%, 1.9%, 9.6%, and 3.8%, respectively (P>0.05). This study showed that there is no correlation between urinary nitrite results and bacterial resistance to antimicrobial drugs. Therefore, it seems that physicians should not adjust antibiotic therapy for UTI based on nitrite results.

  4. Effect of Nitrite Inhibitor on the Macrocell Corrosion Behavior of Reinforcing Steel

    Directory of Open Access Journals (Sweden)

    Zhonglu Cao

    2015-01-01

    Full Text Available The effect of nitrite ions on the macrocell corrosion behavior of reinforcing steel embedded in cement mortar was investigated by comparing and analyzing the macrocell corrosion current, macrocell polarization ratios, and slopes of anodic and cathodic steels. Based on the experimental results, the relationship between macrocell potential difference and macrocell current density was analyzed, and the mechanism of macrocell corrosion affected by nitrite ions was proposed. The results indicated that nitrite ions had significant impact on the macrocell polarization ratios of cathode and anode. The presence of nitrite could reduce the macrocell current by decreasing the macrocell potential difference and increasing the macrocell polarization resistance of the anode.

  5. Interactions of nitrite with catalase: Enzyme activity and reaction kinetics studies.

    Science.gov (United States)

    Krych-Madej, Justyna; Gebicka, Lidia

    2017-06-01

    Catalase, a heme enzyme, which catalyzes decomposition of hydrogen peroxide to water and molecular oxygen, is one of the main enzymes of the antioxidant defense system of the cell. Nitrite, used as a food preservative has long been regarded as a harmful compound due to its ability to form carcinogenic nitrosamines. Recently, much evidence has been presented that nitrite plays a protective role as a nitric oxide donor under hypoxic conditions. In this work the effect of nitrite on the catalytic reactions of catalase was studied. Catalase was inhibited by nitrite, and this process was pH-dependent. IC 50 values varied from about 1μM at pH5.0 to about 150μM of nitrite at pH7.4. The presence of chloride significantly enhanced nitrite-induced catalase inhibition, in agreement with earlier observations. The kinetics of the reactions of nitrite with ferric catalase, its redox intermediate, Compound I, and catalase inactive form, Compound II, was also studied. Possible mechanisms of nitrite-induced catalase inhibition are analyzed and the biological consequences of the reactions of catalase with nitrite are discussed. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Hydrogen bubble dynamic template fabrication of nanoporous Cu film supported by graphene nanaosheets: A highly sensitive sensor for detection of nitrite.

    Science.gov (United States)

    Majidi, Mir Reza; Ghaderi, Seyran

    2017-12-01

    High surface area nanoporous Cu film (NPCF) has been successfully synthesized using a hydrogen bubble dynamic template on the graphene nanosheets (GNs) modified glassy carbon electrode (GCE). The effect of different synthesis conditions such as applied potential and deposition time on the NPCF morphology was investigated. The structure and constituent of the NPCF-GNs/GCE were characterized by scanning electron microscopy (SEM), energy-dispersive x-ray (EDX), X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS) and electrochemical methods. The study on electrocatalytic performance of the NPCF-GNs/GCE demonstrated that this electrode has excellent catalytic activity toward nitrite oxidation. The quantitative measurement of nitrite by amperometric method showed a wide concentration range (0.1-100µmolL -1 ) with a detection limit and a sensitivity of 8.87 × 10 -8 molL -1 and 3.1 AL/molcm 2 , respectively. The excellent electrochemical response and high sensitivity of the proposed electrode were attributed to the 3D structure of NPCF and the synergic effect of NPCF and GNs. Furthermore, this electrode showed some other advantages including good repeatability, high reproducibility, long-term stability and anti-interference performance toward nitrite sensing. The applicability of the proposed electrode was proved by successful determination of nitrite in real samples (tap water, river water and sausage samples). Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Effect of sodium nitrite on renal function, sodium and water excretion and brachial and central blood pressure in healthy subjects. A dose-response study

    DEFF Research Database (Denmark)

    Rosenbaek, Jeppe Bakkestroem; Therwani, Safa Al; Jensen, Janni Majgaard

    2017-01-01

    Sodium nitrite (NaNO2) is converted to nitric oxide (NO) in vivo and has vasodilatory and natriuretic effects. Our aim was to examine the effects of NaNO2 on hemodynamics, sodium excretion and GFR. In a single-blinded, placebo-controlled, cross-over study, we infused placebo (0.9% NaCl) or 0.58, ....... The lack of increase in cGMP accompanying the increase in NO2(-), suggests a direct effect of nitrite or nitrate on the renal tubules and vascular bed with little or no systemic conversion to NO.......Sodium nitrite (NaNO2) is converted to nitric oxide (NO) in vivo and has vasodilatory and natriuretic effects. Our aim was to examine the effects of NaNO2 on hemodynamics, sodium excretion and GFR. In a single-blinded, placebo-controlled, cross-over study, we infused placebo (0.9% NaCl) or 0.58, 1.......74, or 3.48 μmol NaNO2/kg/hour for two hours in twelve healthy subjects, after four days standard diet. Subjects were supine and water-loaded. We measured brachial and central blood pressure (BP), plasma concentrations of renin, angiotensin II, aldosterone, arginine vasopressin (P-AVP), and plasma nitrite...

  8. Microbial competition among anammox bacteria in nitrite-limited bioreactors

    KAUST Repository

    Zhang, Lei; Narita, Yuko; Gao, Lin; Ali, Muhammad; Oshiki, Mamoru; Ishii, Satoshi; Okabe, Satoshi

    2017-01-01

    Phylogenetically diverse anammox bacteria have been detected in most of anoxic natural and engineered ecosystems and thus regarded as key players in the global nitrogen cycle. However, ecological niche differentiation of anammox bacteria remains unresolved despite its ecological and practical importance. In this study, the microbial competitions for a common substrate (nitrite) among three anammox species (i.e. “Candidatus Brocadia sinica”, “Candidatus Jettenia caeni” and “Candidatus Kuenenia stuttgartiensis”) were systematically investigated in nitrite-limited gel-immobilized column reactors (GICR) and membrane bioreactors (MBRs) under different nitrogen loading rates (NLRs). 16 S rRNA gene-based population dynamics revealed that “Ca. J. caeni” could proliferate only at low NLRs, whereas “Ca. B. sinica” outcompeted other two species at higher NLRs in both types of reactors. Furthermore, FISH analysis revealed that “Ca. J. caeni” was mainly present as spherical microclusters at the inner part (low NO2− environment), whereas “Ca. B. sinica” was present throughout the gel beads and granules. This spatial distribution supports the outcomes of the competition experiments. However, the successful competition of “Ca. J. caeni” at low NLR could not be explained with the Monod model probably due to inaccuracy of kinetic parameters such as half saturation constant (Ks) for nitrite and a difference in the maintenance rate (m). In addition, the growth of “Ca. K. stuttgartiensis” could not be observed in any experimental conditions, suggesting possible unknown factor(s) is missing. Taken together, NLR was one of factors determining ecological niche differentiation of “Ca. B. sinica” and “Ca. J. caeni”.

  9. Nitrate ammonification in mangrove soils: A hidden source of nitrite?

    Directory of Open Access Journals (Sweden)

    Melike eBalk

    2015-03-01

    Full Text Available Nitrate reduction is considered to be a minor microbial pathway in the oxidation of mangrove-derived organic matter due to a limited supply of nitrate in mangrove soils. At a limited availability of this electron acceptor compared to the supply of degradable carbon, nitrate ammonification is thought to be the preferential pathway of nitrate reduction. Mangrove forest mutually differ in their productivity, which may lead to different available carbon to nitrate ratios in their soil. Hence, nitrate ammonification is expected to be of more importance in high- compared to low-productive forests.The hypothesis was tested in flow-through reactors that contain undisturbed mangrove soils from high-productive Avicennia germinans and Rhizophora mangle forests in Florida and low-productive Avicennia marina forests in Saudi Arabia. Nitrate was undetectable in the soils from both regions. It was assumed that a legacy of nitrate ammonification would be reflected by a higher ammonium production from these soils upon the addition of nitrate. Unexpectedly, the soils from the low-productive forests in Saudi Arabia produced considerably more ammonium than the soils from the high-productive forests in Florida. Hence, other environmental factors than productivity must govern the selection of nitrate ammonification or denitrification. A rather intriguing observation was the 1:1 production of nitrite and ammonium during the consumption of nitrate, more or less independent from sampling region, location, sampling depth, mangrove species and from the absence or presence of additional degradable carbon. This 1:1 ratio points to a coupled production of ammonium and nitrite by one group of nitrate-reducing microorganisms. Such a production of nitrite will be hidden under the nitrate-limited conditions of most mangrove forest soils.

  10. Microbial competition among anammox bacteria in nitrite-limited bioreactors

    KAUST Repository

    Zhang, Lei

    2017-08-26

    Phylogenetically diverse anammox bacteria have been detected in most of anoxic natural and engineered ecosystems and thus regarded as key players in the global nitrogen cycle. However, ecological niche differentiation of anammox bacteria remains unresolved despite its ecological and practical importance. In this study, the microbial competitions for a common substrate (nitrite) among three anammox species (i.e. “Candidatus Brocadia sinica”, “Candidatus Jettenia caeni” and “Candidatus Kuenenia stuttgartiensis”) were systematically investigated in nitrite-limited gel-immobilized column reactors (GICR) and membrane bioreactors (MBRs) under different nitrogen loading rates (NLRs). 16 S rRNA gene-based population dynamics revealed that “Ca. J. caeni” could proliferate only at low NLRs, whereas “Ca. B. sinica” outcompeted other two species at higher NLRs in both types of reactors. Furthermore, FISH analysis revealed that “Ca. J. caeni” was mainly present as spherical microclusters at the inner part (low NO2− environment), whereas “Ca. B. sinica” was present throughout the gel beads and granules. This spatial distribution supports the outcomes of the competition experiments. However, the successful competition of “Ca. J. caeni” at low NLR could not be explained with the Monod model probably due to inaccuracy of kinetic parameters such as half saturation constant (Ks) for nitrite and a difference in the maintenance rate (m). In addition, the growth of “Ca. K. stuttgartiensis” could not be observed in any experimental conditions, suggesting possible unknown factor(s) is missing. Taken together, NLR was one of factors determining ecological niche differentiation of “Ca. B. sinica” and “Ca. J. caeni”.

  11. Artificial Neural Networks and Concentration Residual Augmented ...

    African Journals Online (AJOL)

    component analysis (PCA) and ANN model was run. The scores ... set) were prepared to measure the predictive power of the .... techniques to find robust and precise solutions. The ANN can ... quality control analysis of this quaternary mixture.

  12. Smart operation of nitritation/denitritation virtually abolishes nitrous oxide emission during treatment of co-digested pig slurry centrate.

    Science.gov (United States)

    Peng, Lai; Carvajal-Arroyo, José M; Seuntjens, Dries; Prat, Delphine; Colica, Giovanni; Pintucci, Cristina; Vlaeminck, Siegfried E

    2017-12-15

    The implementation of nitritation/denitritation (Nit/DNit) as alternative to nitrification/denitrification (N/DN) is driven by operational cost savings, e.g. 1.0-1.8 EUR/ton slurry treated. However, as for any biological nitrogen removal process, Nit/DNit can emit the potent greenhouse gas nitrous oxide (N 2 O). Challenges remain in understanding formation mechanisms and in mitigating the emissions, particularly at a low ratio of organic carbon consumption to nitrogen removal (COD rem /N rem ). In this study, the centrate (centrifuge supernatant) from anaerobic co-digestion of pig slurry was treated in a sequencing batch reactor. The process removed approximately 100% of ammonium a satisfactory nitrogen loading rate (0.4 g N/L/d), with minimum nitrite and nitrate in the effluent. Substantial N 2 O emission (around 17% of the ammonium nitrogen loading) was observed at the baseline operational condition (dissolved oxygen, DO, levels averaged at 0.85 mg O 2 /L; COD rem /N rem of 2.8) with ∼68% of the total emission contributed by nitritation. Emissions increased with higher nitrite accumulation and lower organic carbon to nitrogen ratio. Yet, higher DO levels (∼2.2 mg O 2 /L) lowered the aerobic N 2 O emission and weakened the dependency on nitrite concentration, suggesting a shift in N 2 O production pathway. The most effective N 2 O mitigation strategy combined intermittent patterns of aeration, anoxic feeding and anoxic carbon dosage, decreasing emission by over 99% (down to ∼0.12% of the ammonium nitrogen loading). Without anaerobic digestion, mitigated Nit/DNit decreases the operational carbon footprint with about 80% compared to N/DN. With anaerobic digestion included, about 4 times more carbon is sequestered. In conclusion, the low COD rem /N rem feature of Nit/DNit no longer offsets its environmental sustainability provided the process is smartly operated. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Rapid visual and spectrophotometric nitrite detection by cyclometalated ruthenium complex.

    Science.gov (United States)

    Lo, Hoi-Shing; Lo, Ka-Wai; Yeung, Chi-Fung; Wong, Chun-Yuen

    2017-10-16

    Quantitative determination of nitrite ion (NO 2 - ) is of great importance in environmental and clinical investigations. A rapid visual and spectrophotometric assay for NO 2 - detection was developed based on a newly designed ruthenium complex, [Ru(npy)([9]aneS3)(CO)](ClO 4 ) (denoted as RuNPY; npy = 2-(1-naphthyl)pyridine, [9]aneS3 = 1,4,7-trithiacyclononane). This complex traps NO + produced in acidified NO 2 - solution, and yields observable color change within 1 min at room temperature. The assay features excellent dynamic range (1-840 μmol L -1 ) and high selectivity, and its limit of detection (0.39 μmol L -1 ) is also well below the guideline values for drinking water recommended by WHO and U.S. EPA. Practical use of this assay in tap water and human urine was successfully demonstrated. Overall, the rapidity and selectivity of this assay overcome the problems suffered by the commonly used modified Griess assays for nitrite determination. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Isotopic evidence for nitrous oxide production pathways in a partial nitritation-anammox reactor.

    Science.gov (United States)

    Harris, Eliza; Joss, Adriano; Emmenegger, Lukas; Kipf, Marco; Wolf, Benjamin; Mohn, Joachim; Wunderlin, Pascal

    2015-10-15

    Nitrous oxide (N2O) production pathways in a single stage, continuously fed partial nitritation-anammox reactor were investigated using online isotopic analysis of offgas N2O with quantum cascade laser absorption spectroscopy (QCLAS). N2O emissions increased when reactor operating conditions were not optimal, for example, high dissolved oxygen concentration. SP measurements indicated that the increase in N2O was due to enhanced nitrifier denitrification, generally related to nitrite build-up in the reactor. The results of this study confirm that process control via online N2O monitoring is an ideal method to detect imbalances in reactor operation and regulate aeration, to ensure optimal reactor conditions and minimise N2O emissions. Under normal operating conditions, the N2O isotopic site preference (SP) was much higher than expected - up to 40‰ - which could not be explained within the current understanding of N2O production pathways. Various targeted experiments were conducted to investigate the characteristics of N2O formation in the reactor. The high SP measurements during both normal operating and experimental conditions could potentially be explained by a number of hypotheses: i) unexpectedly strong heterotrophic N2O reduction, ii) unknown inorganic or anammox-associated N2O production pathway, iii) previous underestimation of SP fractionation during N2O production from NH2OH, or strong variations in SP from this pathway depending on reactor conditions. The second hypothesis - an unknown or incompletely characterised production pathway - was most consistent with results, however the other possibilities cannot be discounted. Further experiments are needed to distinguish between these hypotheses and fully resolve N2O production pathways in PN-anammox systems. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Low-fat frankfurters formulated with a healthier lipid combination as functional ingredient: microstructure, lipid oxidation, nitrite content, microbiological changes and biogenic amine formation.

    Science.gov (United States)

    Delgado-Pando, Gonzalo; Cofrades, Susana; Ruiz-Capillas, Claudia; Solas, Maria Teresa; Triki, Mehdi; Jiménez-Colmenero, Francisco

    2011-09-01

    Oil (healthier lipid combination of olive, linseed and fish oils)-in-water emulsions stabilized with different protein systems (prepared with sodium caseinate (SC), soy protein isolate (SPI), and microbial transglutaminase (MTG)) were used as pork backfat replacers in low-fat frankfurters. Microstructure, lipid oxidation, nitrite content, microbiological changes and biogenic amine formation of frankfurters were analyzed and found to be affected by the type of oil-in-water emulsion and by chilling storage (2° C, 41 days). Although the lipid oxidation levels attained were low, replacement of animal fat by healthier oil combinations in frankfurter formulation did promote a slight increase in lipid oxidation. Residual nitrite was affected (P nitrite was detectable in the product after processing and 17-46% at the end of storage. The microbial population was low in all formulations during chilling storage. Spermine was the most abundant amine (19-20 mg/kg), but similar in level to all samples. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. Residual nilpotence and residual solubility of groups

    International Nuclear Information System (INIS)

    Mikhailov, R V

    2005-01-01

    The properties of the residual nilpotence and the residual solubility of groups are studied. The main objects under investigation are the class of residually nilpotent groups such that each central extension of these groups is also residually nilpotent and the class of residually soluble groups such that each Abelian extension of these groups is residually soluble. Various examples of groups not belonging to these classes are constructed by homological methods and methods of the theory of modules over group rings. Several applications of the theory under consideration are presented and problems concerning the residual nilpotence of one-relator groups are considered.

  17. Americium recovery from reduction residues

    Science.gov (United States)

    Conner, W.V.; Proctor, S.G.

    1973-12-25

    A process for separation and recovery of americium values from container or bomb'' reduction residues comprising dissolving the residues in a suitable acid, adjusting the hydrogen ion concentration to a desired level by adding a base, precipitating the americium as americium oxalate by adding oxalic acid, digesting the solution, separating the precipitate, and thereafter calcining the americium oxalate precipitate to form americium oxide. (Official Gazette)

  18. Effect of dietary supplementation of vitamin C on growth, reactive oxygen species, and antioxidant enzyme activity of Apostichopus japonicus (Selenka) juveniles exposed to nitrite

    Science.gov (United States)

    Luo, Zuoyong; Wang, Baojie; Liu, Mei; Jiang, Keyong; Liu, Mingxing; Wang, Lei

    2014-07-01

    Different amounts of vitamin C were added to diets fed to juveniles (2.5 ± 0.15 g) of sea cucumber Apostichopus japonic u s (Selenka) in an attempt to reduce the stress response of specimens exposed to nitrite stress. A commercial feed was used as the control diet and three experimental diets were made by supplementing 1 000, 1 500, or 2 000 mg vitamin C/kg diet to control diet separately in a 45-day experiment. Sea cucumbers were exposed to three different levels (0.5, 1.0, and 1.5 mg/L) of nitrite stress for 4, 8, and 12 h at four time intervals (0, 15, 30, and 45 d). Growth of the animals was recorded during the experiment. Reactive oxygen species (ROS) (i.e. hydroxyl free radical (-OH), malondialdehyde (MDA) and total antioxidant capacity (T-AOC)) and antioxidant enzyme activities (i.e., superoxide dismutase (SOD) and catalase (CAT)) were measured. Response surface methodology (RSM) was used to analyze the effect of multiple factors on ROS indices and enzyme activities. Weight gain (WG) and special growth rate (SGR) of vitamin C supplementation groups were significantly higher than those of control group ( P < 0.05). The levels of -OH and MDA increased under exposure time extending and nitrite concentration increasing, whereas T-AOC level decreased. SOD and CAT activities increased at 4 h and 8 h and decreased at 12 h. During the days in which the animal consumed experimental diets, the levels of -OH and MDA decreased and that of T-AOC increased. This result suggests that diets containing vitamin C could reduce the nitrite stress response in the animals and increase their antioxidant capacity. The multifactor regression equation of growth performance, ROS indices, and duration of feeding results suggest that vitamin C supplementation of 1 400-2 000 mg/kg diet for 29-35 days could reduce effectively the effects of nitrite exposure.

  19. Effect of Electrolytes on the Adsorption of Nitrite and Nitrate from ...

    African Journals Online (AJOL)

    Nitrite and nitrate levels were quantitatively adsorbed to wood-derived activated carbon in aqueous system and the effects of electrolytes investigated in this study using batch sorption process. The data showed that nitrate adsorbed nearly 1.5 times higher than that of nitrite. The adsorption is adequately explained by ...

  20. Green Alternatives to Nitrates and Nitrites in Meat-based Products-A Review.

    Science.gov (United States)

    Gassara, Fatma; Kouassi, Anne Patricia; Brar, Satinder Kaur; Belkacemi, Khaled

    2016-10-02

    Several food additives are added in food for their preservation to maintain the freshness of food (antioxidants) or to slow down or stop the growth of microorganisms (preservative agents). Nitrites and nitrates are used as preservative agents in meat. Nitrites give a smoked taste, a pinkish color in the meat and protect the consumers against the risk of bacterial deterioration. Their addition is however very limited as, in high dose, it can have risks on human health and the environment. Nitrites may also combine with secondary or tertiary amines to form N-nitroso derivatives. Certain N-nitroso compounds have been shown to produce cancers in a wide range of laboratory animals. Thus, alternatives of nitrates and nitrites are the object of numerous research studies. Alternatives, such as the addition of vitamins, fruits, chemicals products, natural products containing nitrite or spices, which have similar properties of nitrites, are in evaluation. In fact, spices are considered to have several organoleptic and anti-microbial properties which would be interesting to study. Several spices and combinations of spices are being progressively evaluated. This review discusses the sources of nitrites and nitrates, their use as additives in food products, their physicochemical properties, their negatives effects and the use of alternatives of nitrites and nitrates in preserving meat products.

  1. Effect of sodium nitrite on toxin production by Clostridium botulinum in bacon.

    Science.gov (United States)

    Christiansen, L N; Tompkin, R B; Shaparis, A B; Kueper, T V; Johnston, R W; Kautter, D A; Kolari, O J

    1974-04-01

    Pork bellies were formulated to 0, 30, 60, 120, 170, or 340 mug of nitrite per g of meat and inoculated with Clostridium botulinum via pickle or after processing and slicing. Processed bacon was stored at 7 or 27 C and assayed for nitrite, nitrate, and botulinal toxin at different intervals. Nitrite levels declined during processing and storage. The rate of decrease was more rapid at 27 than at 7 C. Although not added to the system, nitrate was detected in samples during processing and storage at 7 and 27 C. The amount of nitrate found was related to formulated nitrite levels. No toxin was found in samples incubated at 7 C throughout the 84-day test period. At 27 C, via pickle, inoculated samples with low inoculum (210 C. botulinum per g before processing and 52 per g after processing) became toxic if formulated with 120 mug of nitrite per g of meat or less. Toxin was not detected in bacon formulated with 170 or 340 mug of nitrite per g of meat under these same conditions. Toxin was detected at all formulated nitrite levels in bacon inoculated via the pickle with 19,000 C. botulinum per g (4,300 per g after processing) and in samples inoculated after slicing. However, increased levels of formulated nitrite decreased the probability of botulinal toxin formation in bacon inoculated by both methods.

  2. Nitrate and nitrite content in bottled beverages by ion-pair high-performance liquid chromatography.

    Science.gov (United States)

    Song, Yang; Deng, Gui-Fang; Xu, Xiang-Rong; Chen, Yong-Hong; Chen, Feng; Li, Hua-Bin

    2013-01-01

    Nitrate and nitrite levels in six types of beverages--total of 292 individual samples from 73 brands (four bottles each)--from Guangzhou city in China were evaluated by ion-pair high-performance liquid chromatography. All samples contained nitrate. Nitrate and nitrite ranges were 0.43-46.08 and safety of Chinese bottled beverages.

  3. Electrochemical Biosensor for Nitrite Based on Polyacrylic-Graphene Composite Film with Covalently Immobilized Hemoglobin

    Directory of Open Access Journals (Sweden)

    Raja Zaidatul Akhmar Raja Jamaluddin

    2018-04-01

    Full Text Available A new biosensor for the analysis of nitrite in food was developed based on hemoglobin (Hb covalently immobilized on the succinimide functionalized poly(n-butyl acrylate-graphene [poly(nBA-rGO] composite film deposited on a carbon-paste screen-printed electrode (SPE. The immobilized Hb on the poly(nBA-rGO conducting matrix exhibited electrocatalytic ability for the reduction of nitrite with significant enhancement in the reduction peak at −0.6 V versus Ag/AgCl reference electrode. Thus, direct determination of nitrite can be achieved by monitoring the cathodic peak current signal of the proposed polyacrylic-graphene hybrid film-based voltammetric nitrite biosensor. The nitrite biosensor exhibited a reproducible dynamic linear response range from 0.05–5 mg L−1 nitrite and a detection limit of 0.03 mg L−1. No significant interference was observed by potential interfering ions such as Ca2+, Na+, K+, NH4+, Mg2+, and NO3− ions. Analysis of nitrite in both raw and processed edible bird’s nest (EBN samples demonstrated recovery of close to 100%. The covalent immobilization of Hb on poly(nBA-rGO composite film has improved the performance of the electrochemical nitrite biosensor in terms of broader detection range, lower detection limit, and prolonged biosensor stability.

  4. Electrochemical detection of nitrite based on the polythionine/carbon nanotube modified electrode

    International Nuclear Information System (INIS)

    Deng, Chunyan; Chen, Jinzhuo; Nie, Zhou; Yang, Minghui; Si, Shihui

    2012-01-01

    In this paper, thionine was electro-polymerized onto the surface of carbon nanotube (CNT)-modified glassy carbon (GC) to fabricate the polythionine (PTH)/CNT/GC electrode. It was found that the electro-reduction current of nitrite was enhanced greatly at the PTH/CNT/GC electrode. It may be demonstrated that PTH was used as a mediator for electrocatalytic reduction of nitrite, and CNTs as an excellent nanomaterial can improve the electron transfer between the electrode and nitrite. Therefore, based on the synergic effect of PTH and CNTs, the PTH/CNT/GC electrode was employed to detect nitrite, and the high sensitivity of 5.81 μA mM −1 , and the detection limit of 1.4 × 10 −6 M were obtained. Besides, the modified electrode showed an inherent stability, fast response time, and good anti-interference ability. These suggested that the PTH/CNT/GC electrode was favorable and reliable for the detection of nitrite. - Highlights: ► Polythionine (PTH) was used as a mediator for electrocatalytic reduction of nitrite. ► Carbon nanotubes (CNTs) improve electron transfer between the electrode and nitrite. ► The PTH/CNT/glassy carbon electrode showed excellent nitrite detection performance.

  5. Bioavailability of sodium nitrite from an aqueous solution in healthy adults.

    NARCIS (Netherlands)

    Hunault, C.C.; van Velzen, A.G.; Sips, A.J.; Schothorst, R.C.; Meulenbelt, J.|info:eu-repo/dai/nl/079479227

    2009-01-01

    Nitrate intake in humans is high through intake of vegetables such as beets, lettuce, and spinach. Nitrate itself is a compound of low toxicity but its metabolite, nitrite, formed by bacteria in the oral cavity and gastrointestinal tract, has been suspected of potential carcinogenic effects. Nitrite

  6. Review of environmental exposure concentrations of chemical warfare agent residues and associated the fish community risk following the construction and completion of the Nord Stream gas pipeline between Russia and Germany.

    Science.gov (United States)

    Sanderson, Hans; Fauser, Patrik; Rahbek, Malene; Larsen, Jørn Bo

    2014-08-30

    This paper compiles all the measured chemical warfare agent (CWA) concentrations found in relation to the Nord Stream pipeline work in Danish waters for the past 5 years. Sediment and biota sampling were performed along the pipeline route in four campaigns, prior to (in 2008 and 2010), during (in 2011) and after (in 2012) the construction work. No parent CWAs were detected in the sediments. Patchy residues of CWA degradation products of Adamsite, Clark I, phenyldichloroarsine, trichloroarsine and Lewisite II, were detected in a total of 29 of the 391 sediment samples collected and analyzed the past 5 years. The cumulative fish community risk quotient for the different locations, calculated as a sum of background and added risk, ranged between 0 and 0.017 suggesting a negligible acute CWA risk toward the fish community. The added risk from sediment disturbance in relation to construction of the pipelines represents less than 2% of the total risk in the areas with the highest calculated risk. The analyses of benthic infauna corroborate the finding of CWA related low risk across the years. There was no significant difference in CWA risk before (2008) and after the pipeline construction (2012). Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Electrochemical Single‐Molecule AFM of the Redox Metalloenzyme Copper Nitrite Reductase in Action

    DEFF Research Database (Denmark)

    Hao, Xian; Zhang, Jingdong; Christensen, Hans Erik Mølager

    2012-01-01

    We studied the electrochemical behavior of the redox metalloenzyme copper nitrite reductase (CNiR, Achromobacter xylosoxidans) immobilized on a Au(111)‐electrode surface modified by a self‐assembled cysteamine molecular monolayer (SAM) using a combination of cyclic voltammetry and electrochemically......‐controlled atomic force microscopy (in situ AFM). The enzyme showed no voltammetric signals in the absence of nitrite substrate, whereas a strong reductive electrocatalytic signal appeared in the presence of nitrite. Such a pattern is common in protein film and monolayer voltammetry and points to conformational...... in the presence of nitrite. No change in size was observed in the absence of nitrite over the same potential range. The enzyme size variation is suggested to offer clues to the broadly observed substrate triggering in metalloenzyme monolayer voltammetry....

  8. Evaluation of nitrite contamination in baby foods and infant formulas marketed in Turkey.

    Science.gov (United States)

    Erkekoglu, Pinar; Baydar, Terken

    2009-05-01

    Nitrites are responsible for methemoglobinemia, to which infants younger than 6 months are thought to be the most susceptible population. This study aimed to detect whether there was any nitrite contamination in infant formulas and baby foods marketed in Turkey and to estimate possible toxicological risks in this sensitive physiological period. For this purpose, the samples were randomly collected and divided into four groups: milk-based, cereal-based, vegetable-based, and fruit-based. An easy and reliable spectrophotometric method was used by modifying the Griess method. The average nitrite contamination was found to be 204.07+/-65.80 microg/g in 42 samples, with 1,073 microg/g maximum. According to the results, baby and infant formulas include various nitrite levels; nitrite contamination might come from several sources during manufacturing, and so extreme attention must be given throughout the manufacturing process of food for infants.

  9. The steady-state kinetics of the NADH-dependent nitrite reductase from Escherichia coli K 12. Nitrite and hydroxylamine reduction.

    Science.gov (United States)

    Jackson, R H; Cole, J A; Cornish-Bowden, A

    1981-01-01

    The reduction of both NO2- and hydroxylamine by the NADH-dependent nitrite reductase of Escherichia coli K 12 (EC 1.6.6.4) appears to follow Michaelis-Menten kinetics over a wide range of NADH concentrations. Substrate inhibition can, however, be detected at low concentrations of the product NAD+. In addition, NAD+ displays mixed product inhibition with respect to NADH and mixed or uncompetitive inhibition with respect to hydroxylamine. These inhibition characteristics are consistent with a mechanism in which hydroxylamine binds during catalysis to a different enzyme form from that generated when NAD+ is released. The apparent maximum velocity with NADH as varied substrate increases as the NAD+ concentration increases from 0.05 to 0.7 mM with 1 mM-NO2- or 100 mM-hydroxylamine as oxidized substrate. This increase is more marked for hydroxylamine reduction than for NO2- reduction. Models incorporating only one binding site for NAD can account for the variation in the Michaelis-Menten parameters for both NADH and hydroxylamine with [NAD+] for hydroxylamine reduction. According to these models, activation of the reaction occurs by reversal of an over-reduction of the enzyme by NADH. If the observed activation of the enzyme by NAD+ derives both from activation of the generation of the enzyme-hydroxylamine complex from the enzyme-NO2- complex during NO2- reduction and from activation of the reduction of the enzyme-hydroxylamine complex to form NH4+, then the variation of Vapp. for NO2- or hydroxylamine with [NAD+] is consistent with the occurrence of the same enzyme-hydroxylamine complex as an intermediate in both reactions. PMID:6279095

  10. FIA-automated system used to electrochemically measure nitrite and its interfering chemicals through a 1-2 DAB / Au electrode: gain of sensitivity at upper potentials

    Science.gov (United States)

    Almeida, F. L.; dos Santos Filho, S. G.; Fontes, M. B. A.

    2013-03-01

    The measurement of nitrite and its interfering-chemicals (paracetamol, ascorbic acid and uric acid) was performed employing a Flow-injection Analysis (FIA) system, which was automated using solenoid valves and air-pump. It is very important to quantify nitrite from river water, food and biologic fluids due to its antibacterial capacity in moderated concentrations, or its toxicity for human health even at low concentrations (> 20 μmol L-1 in blood fluids). Electrodes of the electrochemical planar sensor were defined by silk-screen technology. The measuring electrode was made from gold paste covered with 1-2 cis Diaminobenzene (DAB), which allowed good selectivity, linearity, repeatability, stability and optimized gain of sensitivity at 0.5 VAg/AgCl Nafion®117 (6.93 μA mol-1 L mm-2) compared to 0.3 VAg/AgCl Nafion® 117. The reference electrode was obtained from silver/palladium paste modified with chloride and covered with Nafion® 117. The auxiliary electrode was made from platinum paste. It was noteworthy that nitrite response adds to the response of the studied interfering-chemicals and it is predominant for concentrations lower than 175 μmol L-1.

  11. EXHALED AND PLASMA NITRITE: a comparative study among healthy, cirrhotic and liver transplant patients

    Directory of Open Access Journals (Sweden)

    Viviane S AUGUSTO

    2014-03-01

    Full Text Available Context There is a relative lack of studies about exhaled nitrite (NO2- concentrations in cirrhotic and transplanted patients. Objective Verify possible differences and correlations between the levels of NO2-, measured in plasma and exhaled breath condensate collected from patients with cirrhosis and liver transplant. Method Sixty adult male patients, aged between 27 and 67 years, were subdivided into three groups: a control group comprised of 15 healthy volunteers, a cirrhosis group composed of 15 volunteers, and a transplant group comprised of 30 volunteers. The NO2- concentrations were measured by chemiluminescence. Results 1 The analysis of plasma NO2- held among the three groups showed no statistical significance. 2 The comparison between cirrhotic and control groups, control and transplanted and cirrhotic and transplanted was not statistically significant. 3 The measurements performed on of NO2- exhaled breath condensate among the three groups showed no statistical difference. 4 When comparing the control group samples and cirrhotic, control and transplanted and cirrhotic and transplanted, there was no significant changes in the concentrations of NO2-. Conclusion No correlations were found between plasma and exhaled NO2-, suggesting that the exhaled NO2- is more reflective of local respiratory NO release than the systemic circulation.

  12. Radiolysis of nitrite, bromate and permanganate ions and their binary mixtures in aqueous solutions at pH 10

    International Nuclear Information System (INIS)

    Dedgaonkar, V.G.; Kulkarni, S.A.; Mahajan, C.T.

    1981-01-01

    #betta#-radiolysis of pure systems viz. nitrite, bromate and permanganate and their binary mixtures (MNO 4- /NO 2- , MnO 4- /BrO 3- ) in aqueous solution at pH 10 is studied as a function of dose and concentration. In pure systems the G(NO 3- ), G(Br - ) and G(-MnO 4- ) increase with increasing concentration. The first two show an identical limiting value of approximately 0.5 while the last increases from 0.68 below 10 4 M and reaches 2.5 at 10 - 2 M concentration. Presence of 10 - 1 M BrO 3- or 10 - 2 M NO 2- reduces the G(-MnO 4- ) from 1.07 for the pure 10 - 3 M permanganate solution to 0.2 and 0.7 respectively. A mechanism based on the competitive kinetics is envisaged to explain the observed results. (author)

  13. Removal Efficiency of Nitrite and Sulfide Pollutants by Electrochemical Process by Using Ti/RuIrO2 Anode

    Directory of Open Access Journals (Sweden)

    Aris Mukimin

    2018-05-01

    Full Text Available In general, wastewater treatment by physical, chemical and biological methods are only focused on TSS, BOD and COD removals that the effluent still contains anion pollutant as NO2- and S2-. Electrochemical technology is a proper method for those pollutants treatment due to its fast process, easy operation and minimum amount of sludge. Electrocatalytic reactor with 8 L capacity using Ti/RuIrO2 cylinder as anode and Fe plate as cathode was arranged and applied to treat anion pollutants. Hydraulic retention time (30, 60, 90 and 120 min, salt concentration (250, 500 and 750 mg/L and voltage (4, 5, and 6 V were chosen as operation variables and NO2- and S2- concentrations as parameter indicators. Nitrite removal efficiency reached 75 and 99.7% after 60 and 120 min of electrolysis, respectively, while sulfide could obtain higher efficiency, i.e., 97 and 99.9% after 60 and 90 min, respectively, at operation variables of potential of 5 V and salt of 500 mg/L. Removal process is dominated by indirect oxidation mechanism by HClO/ClO- oxidators generated at anode surface as intermediate products. The lifespan of electrode and electric consumption are two main factors of operation cost. Electric consumed was 0.452 kWh per 1 g nitrite removed.

  14. Characterisation and management of concrete grinding residuals.

    Science.gov (United States)

    Kluge, Matt; Gupta, Nautasha; Watts, Ben; Chadik, Paul A; Ferraro, Christopher; Townsend, Timothy G

    2018-02-01

    Concrete grinding residue is the waste product resulting from the grinding, cutting, and resurfacing of concrete pavement. Potential beneficial applications for concrete grinding residue include use as a soil amendment and as a construction material, including as an additive to Portland cement concrete. Concrete grinding residue exhibits a high pH, and though not hazardous, it is sufficiently elevated that precautions need to be taken around aquatic ecosystems. Best management practices and state regulations focus on reducing the impact on such aquatic environment. Heavy metals are present in concrete grinding residue, but concentrations are of the same magnitude as typically recycled concrete residuals. The chemical composition of concrete grinding residue makes it a useful product for some soil amendment purposes at appropriate land application rates. The presence of unreacted concrete in concrete grinding residue was examined for potential use as partial replacement of cement in new concrete. Testing of Florida concrete grinding residue revealed no dramatic reactivity or improvement in mortar strength.

  15. Intake assessment of the food additives nitrite (E 249 and E 250) and nitrate (E 251 and E 252)

    NARCIS (Netherlands)

    Sprong RC; Niekerk EM; Beukers MH; VVH; V&Z

    2017-01-01

    Nitrate and nitrite are authorised as preservatives in certain food products, such as salami, ham (nitrite) and cheese (nitrate). They prevent food spoilage and protect the consumer against food-borne pathogens. Next to that, nitrate and nitrite play a role in food colour retention and contribute to

  16. Spatial interaction of archaeal ammonia-oxidizers and nitrite-oxidizing bacteria in an unfertilized grassland soil

    Directory of Open Access Journals (Sweden)

    Barbara eStempfhuber

    2016-01-01

    Full Text Available Interrelated successive transformation steps of nitrification are performed by distinct microbial groups – the ammonia-oxidizers, comprising ammonia-oxidizing archaea (AOA and bacteria (AOB, and nitrite-oxidizers such as Nitrobacter and Nitrospira, which are the dominant genera in the investigated soils. Hence, not only their presence and activity in the investigated habitat is required for nitrification, but also their temporal and spatial interactions. To demonstrate the interdependence of both groups and to address factors promoting putative niche differentiation within each group, temporal and spatial changes in nitrifying organisms were monitored in an unfertilized grassland site over an entire vegetation period at the plot scale of 10 m². Nitrifying organisms were assessed by measuring the abundance of marker genes (amoA for AOA and AOB, nxrA for Nitrobacter, 16S rRNA gene for Nitrospira selected for the respective sub-processes. A positive correlation between numerically dominant AOA and Nitrospira, and their co-occurrence at the same spatial scale in August and October, suggests that the nitrification process is predominantly performed by these groups and is restricted to a limited timeframe. Amongst nitrite-oxidizers, niche differentiation was evident in observed seasonally varying patterns of co-occurrence and spatial separation. While their distributions were most likely driven by substrate concentrations, oxygen availability may also have played a role under substrate-limited conditions. Phylogenetic analysis revealed temporal shifts in Nitrospira community composition with an increasing relative abundance of OTU03 assigned to sublineage V from August onwards, indicating its important role in nitrite oxidation.

  17. MWCNT-cysteamine-Nafion modified gold electrode based on myoglobin for determination of hydrogen peroxide and nitrite.

    Science.gov (United States)

    Canbay, Erhan; Şahin, Berika; Kıran, Müge; Akyilmaz, Erol

    2015-02-01

    In this work, a novel amperometric biosensor of hydrogen peroxide (H2O2) was developed based on the immobilization of myoglobin (Mb) on the surface of the multi-walled carbon nanotube (MWCNT) -Nafion-cysteamine (CA) modified gold electrode (Au) and its electrocatalytic activity was used for the determination of nitrite (NO2(-)). In the optimization studies, the best MWCNT and myoglobin amount were investigated. It was discovered at the experiments for the optimization of the working conditions that the buffer at this study as 50.0mM, pH7.0 phosphate buffer (PBS) and working temperature as 30°C for the H2O2 biosensor. It was determined at the characterization studies on the biosensor that linear results are obtained between the ranges of 0.1μM to 70.0μM for H2O2 concentration and 1-250μM for NO2(-). The reproducibility of the biosensor was determined both H2O2 and nitrite. From the experiments, average value, standard deviation (SD) and coefficients of variation (CV%) were calculated to be 10.02±0.43μM, and 4.29% for 10.0μM H2O2 (n=6) and 52.0±2.1μM, and 3.89% for 50.0μM nitrite (n=8), respectively. At the same time the sample was analyzed for NO2(-) in drinking and mineral waters. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Differentiation in the microbial ecology and activity of suspended and attached bacteria in a nitritation-anammox process.

    Science.gov (United States)

    Park, Hongkeun; Sundar, Suneethi; Ma, Yiwei; Chandran, Kartik

    2015-02-01

    A directed differentiation between the biofilm and suspension was observed in the molecular microbial ecology and gene expression of different bacteria in a biofilm nitritation-anammox process operated at varying hydraulic residence times (HRT) and nitrogen loading rates (NLR). The highest degree of enrichment observed in the biofilm was of anaerobic ammonia-oxidizing bacteria (AMX) followed by that of Nitrospira spp. related nitrite-oxidizing bacteria (NOB). For AMX, a major shift from Candidatus "Brocadia fulgida" to Candidatus "Kuenenia stuttgartiensis" in both suspension and biofilm was observed with progressively shorter HRT, using discriminatory biomarkers targeting the hydrazine synthase (hzsA) gene. In parallel, expression of the hydrazine oxidoreductase gene (hzo), a functional biomarker for AMX energy metabolism, became progressively prominent in the biofilm. A marginal but statistically significant enrichment in the biofilm was observed for Nitrosomonas europaea related ammonia-oxidizing bacteria (AOB). In direct contrast to AMX, the gene expression of ammonia monooxygenase subunit A (amoA), a functional biomarker for AOB energy metabolism, progressively increased in suspension. Using gene expression and biomass concentration measures in conjunction, it was determined that signatures of AOB metabolism were primarily present in the biofilm throughout the study. On the other hand, AMX metabolism gradually shifted from being uniformly distributed in both the biofilm and suspension to primarily the biofilm at shorter HRTs and higher NLRs. These results therefore highlight the complexity and key differences in the microbial ecology, gene expression and activity between the biofilm and suspension of a nitritation-anammox process and the biokinetic and metabolic drivers for such niche segregation. © 2014 Wiley Periodicals, Inc.

  19. Potential Role of Nitrite for Abiotic Fe(II) Oxidation and Cell Encrustation during Nitrate Reduction by Denitrifying Bacteria

    Science.gov (United States)

    Klueglein, Nicole; Zeitvogel, Fabian; Stierhof, York-Dieter; Floetenmeyer, Matthias; Konhauser, Kurt O.; Obst, Martin

    2014-01-01

    Microorganisms have been observed to oxidize Fe(II) at neutral pH under anoxic and microoxic conditions. While most of the mixotrophic nitrate-reducing Fe(II)-oxidizing bacteria become encrusted with Fe(III)-rich minerals, photoautotrophic and microaerophilic Fe(II) oxidizers avoid cell encrustation. The Fe(II) oxidation mechanisms and the reasons for encrustation remain largely unresolved. Here we used cultivation-based methods and electron microscopy to compare two previously described nitrate-reducing Fe(II) oxidizers ( Acidovorax sp. strain BoFeN1 and Pseudogulbenkiania sp. strain 2002) and two heterotrophic nitrate reducers (Paracoccus denitrificans ATCC 19367 and P. denitrificans Pd 1222). All four strains oxidized ∼8 mM Fe(II) within 5 days in the presence of 5 mM acetate and accumulated nitrite (maximum concentrations of 0.8 to 1.0 mM) in the culture media. Iron(III) minerals, mainly goethite, formed and precipitated extracellularly in close proximity to the cell surface. Interestingly, mineral formation was also observed within the periplasm and cytoplasm; intracellular mineralization is expected to be physiologically disadvantageous, yet acetate consumption continued to be observed even at an advanced stage of Fe(II) oxidation. Extracellular polymeric substances (EPS) were detected by lectin staining with fluorescence microscopy, particularly in the presence of Fe(II), suggesting that EPS production is a response to Fe(II) toxicity or a strategy to decrease encrustation. Based on the data presented here, we propose a nitrite-driven, indirect mechanism of cell encrustation whereby nitrite forms during heterotrophic denitrification and abiotically oxidizes Fe(II). This work adds to the known assemblage of Fe(II)-oxidizing bacteria in nature and complicates our ability to delineate microbial Fe(II) oxidation in ancient microbes preserved as fossils in the geological record. PMID:24271182

  20. Composite of Cu metal nanoparticles-multiwall carbon nanotubes-reduced graphene oxide as a novel and high performance platform of the electrochemical sensor for simultaneous determination of nitrite and nitrate

    Energy Technology Data Exchange (ETDEWEB)

    Bagheri, Hasan, E-mail: h.bagheri@bmsu.ac.ir [Chemical Injuries Research Center, Baqiyatallah University of Medical Sciences, Tehran (Iran, Islamic Republic of); Hajian, Ali [Laboratory for Sensors, Department of Microsystems Engineering (IMTEK), University of Freiburg, Georges Köhler Allee 103, 79110 Freiburg (Germany); Rezaei, Mosayeb; Shirzadmehr, Ali [Young Researchers and Elite Club, Hamedan Branch, Islamic Azad University, Hamedan (Iran, Islamic Republic of)

    2017-02-15

    Highlights: • An electrochemical sensor based on Cu metal nanoparticles-multiwall carbon nanotubes-reduced graphene oxide modified glassy carbon electrode was developed. • Simultaneous electrochemical determination of nitrate and nitrite by fabricated sensor was performed. • Modification improved the sensitivity and detection limit of the method. • It is a useful method for determining of nitrate and nitrite in various real samples. - Abstract: In the present research, we aimed to fabricate a novel electrochemical sensor based on Cu metal nanoparticles on the multiwall carbon nanotubes-reduced graphene oxide nanosheets (Cu/MWCNT/RGO) for individual and simultaneous determination of nitrite and nitrate ions. The morphology of the prepared nanocomposite on the surface of glassy carbon electrode (GCE) was characterized using various methods including scanning electron microscopy (SEM), atomic force microscopy (AFM), and electrochemical impedance spectroscopy. Under optimal experimental conditions, the modified GCE showed excellent catalytic activity toward the electro-reduction of nitrite and nitrate ions (pH = 3.0) with a significant increase in cathodic peak currents in comparison with the unmodified GCE. By square wave voltammetry (SWV) the fabricated sensor demonstrated wide dynamic concentration ranges from 0.1 to 75 μM with detection limits (3S{sub b}/m) of 30 nM and 20 nM method for nitrite and nitrate ions, respectively. Furthermore, the applicability of the proposed modified electrode was demonstrated by measuring the concentration of nitrite and nitrate ions in the tap and mineral waters, sausages, salami, and cheese samples.

  1. Field Test Kit for Gun Residue Detection; TOPICAL

    International Nuclear Information System (INIS)

    WALKER, PAMELA K.; RODACY, PHILIP J.

    2002-01-01

    One of the major needs of the law enforcement field is a product that quickly, accurately, and inexpensively identifies whether a person has recently fired a gun--even if the suspect has attempted to wash the traces of gunpowder off. The Field Test Kit for Gunshot Residue Identification based on Sandia National Laboratories technology works with a wide variety of handguns and other weaponry using gunpowder. There are several organic chemicals in small arms propellants such as nitrocellulose, nitroglycerine, dinitrotoluene, and nitrites left behind after the firing of a gun that result from the incomplete combustion of the gunpowder. Sandia has developed a colorimetric shooter identification kit for in situ detection of gunshot residue (GSR) from a suspect. The test kit is the first of its kind and is small, inexpensive, and easily transported by individual law enforcement personnel requiring minimal training for effective use. It will provide immediate information identifying gunshot residue

  2. Effect of Ethanolamines on Corrosion Inhibition of Ductile Cast Iron in Nitrite Containing Solutions

    International Nuclear Information System (INIS)

    Kim, K. T.; Kim, Y. S.; Chang, H. Y.; Lim, B. T.; Park, H. B.

    2016-01-01

    In this work, synergistic corrosion inhibition effect of nitrite and 3 kinds of ethanolamines on ductile cast iron using chemical and electrochemical methods was evaluated. This work attempts to clarify the synergistic effect of nitrite and ethanolamines. The effects of single addition of TEA, DEA, and MEA, and mixed addition of nitrite plus TEA, DEA or MEA on the corrosion inhibition of ductile cast iron in a tap water were evaluated. A huge amount of single addition of ethanolamine was needed. However, the synergistic effect by mixed addition was observed regardless of the combination of nitrite and triethanolamines, but their effects increased in a series of MEA + nitrite > DEA + nitrite > TEA + nitrite. This tendency of synergistic effect was attributed to the film properties and polar effect; TEA addition couldn't form the film showing high film resistance and semiconductive properties, but DEA or MEA could build the film having relatively high film resistance and n-type semiconductive properties. Moreover, it can be explained that this behaviour was closely related to electron attractive group within the ethanolamines, and thus corrosion inhibition power depends upon the number of the electron attractive group of MEA, DEA, and TEA.

  3. Effect of Ethanolamines on Corrosion Inhibition of Ductile Cast Iron in Nitrite Containing Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K. T.; Kim, Y. S. [Andong National University, Andong (Korea, Republic of); Chang, H. Y.; Lim, B. T.; Park, H. B. [KEPCO Engineering and Construction Company, Gimcheon (Korea, Republic of)

    2016-08-15

    In this work, synergistic corrosion inhibition effect of nitrite and 3 kinds of ethanolamines on ductile cast iron using chemical and electrochemical methods was evaluated. This work attempts to clarify the synergistic effect of nitrite and ethanolamines. The effects of single addition of TEA, DEA, and MEA, and mixed addition of nitrite plus TEA, DEA or MEA on the corrosion inhibition of ductile cast iron in a tap water were evaluated. A huge amount of single addition of ethanolamine was needed. However, the synergistic effect by mixed addition was observed regardless of the combination of nitrite and triethanolamines, but their effects increased in a series of MEA + nitrite > DEA + nitrite > TEA + nitrite. This tendency of synergistic effect was attributed to the film properties and polar effect; TEA addition couldn't form the film showing high film resistance and semiconductive properties, but DEA or MEA could build the film having relatively high film resistance and n-type semiconductive properties. Moreover, it can be explained that this behaviour was closely related to electron attractive group within the ethanolamines, and thus corrosion inhibition power depends upon the number of the electron attractive group of MEA, DEA, and TEA.

  4. Ingested nitrate and nitrite and stomach cancer risk: an updated review.

    Science.gov (United States)

    Bryan, Nathan S; Alexander, Dominik D; Coughlin, James R; Milkowski, Andrew L; Boffetta, Paolo

    2012-10-01

    Nitrite and nitrate are naturally occurring molecules in vegetables and also added to cured and processed meats to delay spoilage and pathogenic bacteria growth. Research over the past 15 years has led to a paradigm change in our ideas about health effects of both nitrite and nitrate. Whereas, historically nitrite and nitrate were considered harmful food additives and listed as probable human carcinogens under conditions where endogenous nitrosation could take place, they are now considered by some as indispensible nutrients essential for cardiovascular health by promoting nitric oxide (NO) production. We provide an update to the literature and knowledge base concerning their safety. Most nitrite and nitrate exposure comes from naturally occurring and endogenous sources and part of the cell signaling effects of NO involve nitrosation. Nitrosation must now be considered broadly in terms of both S- and N-nitrosated species, since S-nitrosation is kinetically favored. Protein S-nitrosation is a significant part of the role of NO in cellular signal transduction and is involved in critical aspects of cardiovascular health. A critical review of the animal toxicology literature of nitrite indicates that in the absence of co-administration of a carcinogenic nitrosamine precursor, there is no evidence for carcinogenesis. Newly published prospective epidemiological cohort studies indicate that there is no association between estimated intake of nitrite and nitrate in the diet and stomach cancer. This new and growing body of evidence calls for a reconsideration of nitrite and nitrate safety. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. Nitrite reduction and methanogenesis in a single-stage UASB reactor.

    Science.gov (United States)

    Borges, L I; López-Vazquez, C M; García, H; van Lier, J B

    2015-01-01

    In this study, nitrite reduction and methanogenesis in a single-stage upflow anaerobic sludge blanket (UASB) reactor was investigated, using high-strength synthetic domestic wastewater as substrate. To assess long-term effects and evaluate the mechanisms that allow successful nitrite reduction and methanogenesis in a single-stage UASB, sludge was exposed to relatively high nitrite loading rates (315 ± 13 mgNO(2)(-)-N/(l.d)), using a chemical oxygen demand (COD) to nitrogen ratio of 18 gCOD/gNO(2)(-)-N, and an organic loading rate of 5.4 ± 0.2 gCOD/(l.d). In parallel, the effects of sludge morphology on methanogenesis inhibition were studied by performing short-term batch activity tests at different COD/NO(2)(-)-N ratios with anaerobic sludge samples. In long-term tests, denitrification was practically complete and COD removal efficiency did not change significantly after nitrite addition. Furthermore, methane production only decreased by 13%, agreeing with the reducing equivalents requirement for complete NO(2)(-) reduction to N₂. Apparently, the spatial separation of denitrification and methanogenesis zones inside the UASB reactor allowed nitrite reduction and methanogenesis to occur at the same moment. Batch tests showed that granules seem to protect methanogens from nitrite inhibition, probably due to transport limitations. Combined COD and N removal via nitrite in a single-stage UASB reactor could be a feasible technology to treat high-strength domestic wastewater.

  6. Nitrogen-Doped Carbon Quantum Dots as Fluorescent Probes for Sensitive and Selective Detection of Nitrite

    Directory of Open Access Journals (Sweden)

    Zhibiao Feng

    2017-11-01

    Full Text Available Nitrites are the upstream precursors of the carcinogenic nitrosamines, which are widely found in the natural environment and many food products. It is important to develop a simple and sensitive sensor for detecting nitrites. In this work, a fluorescence probe based on nitrogen-doped carbon quantum dots (N-CQDs was developed for the sensitive and selective determination of nitrites. At pH 2, the fluorescence of N-CQDs can be selectively quenched by nitrite due to the fact N-nitroso compounds can be formed in the reaction of amide groups with nitrous acid, which results in fluorescence static quenching. Under optimal conditions, fluorescence intensity quenching upon addition of nitrite gives a satisfactory linear relationship covering the linear range of 0.2–20 μM, and the limit of detection (LOD is 40 nM. Moreover, this method has been successfully applied to the determination of nitrites in tap water, which indicates its great potential for monitoring of nitrites in environmental samples.

  7. Preliminary nitrite, nitrate and colour analysis of Malaysian edible bird’s nest

    Directory of Open Access Journals (Sweden)

    Meei Chien Quek

    2015-05-01

    Full Text Available The high nitrite content in edible bird’s nests is a major concern to the local swiftlet industry. It lowers the price of the edible bird’s nests and it brings severe health hazards to consumers and farmers. This research investigated the nitrite and nitrate contents of eight types of local edible bird’s nests by using ion chromatography system and evaluating its colour using the CIE system in L∗a∗b∗ parameters. The nitrite content obtained ranged from 5.7 μg/g for the house nests to 843.8 μg/g for the cave nests. The nitrate content for the house and cave nests was 98.2 μg/g and 36,999.4 μg/g, respectively. The cave nests with darker and redder colour had higher nitrite and nitrate contents than the brighter and more yellow house nests. This likely suggests that the nitrite and nitrate contents have correlations with edible bird’s nests colour. Correlations studies suggested that the nitrite content had high correlations with colour parameters, L∗a∗b∗ of edible bird’s nests at significant level of P < 0.10. These findings suggest that edible bird’s nests’ colour may be a useful indicator for measuring nitrite and nitrate contaminations.

  8. Environmental fate and transport of nitroglycerin from propellant residues at firing positions in the unsaturated zone

    Energy Technology Data Exchange (ETDEWEB)

    Bellavance-Godin, A. [Institut National de la Recherche Scientifique, Quebec, PQ (Canada). Eau, Terre et Environnement; Martel, R. [Institut National de la Recherche Scientifique, Varennes, PQ (Canada). Eau, Terre et Environnement, Earth Sciences

    2008-07-01

    In response to environmental concerns, the Canadian Forces Base (CFB) have initiated studies to better evaluate the impact of various military activities. This paper presented the results of a study in which the fate of propellant residues on large soil columns was investigated. The sites selected for the study were the antitank ranges at Garrison Valcartier, Quebec and those at the CFB Petawawa, Ontario. The shoulder rockets fired on those ranges were propelled by solid propellants based on a nitrocellulose matrix in which nitroglycerine and ammonium perchlorate were dispersed as oxidizer and energetic materials. Propellant residues accumulated in the surface soils because the combustion processes in the rockets was incomplete. This study evaluated the contaminants transport through the unsaturated zone. Sampling was conducted in 2 steps. The first involved collecting uncontaminated soil samples representative of the geological formations of the 2 sites. The second step involved collecting soils containing high levels of propellant residues behind antitank firing positions, which was later spread across the surface of the uncontaminated soil columns and which were representative of the contaminated zone. The soils were watered in the laboratory following the precipitation patterns of the respective regions and interstitial water output of the columns was also sampled. The compounds of interest were nitroglycerine and its degradation metabolites, dinitroglycerine, mononitroglycerine and nitrates as well as perchlorate and bromides. Results presented high concentrations of nitrites, nitrates and perchlorates. Both the NG and its degradation products were monitored using a newly developed analytical method that provides for a better understanding of NG degradation pathways in anaerobic conditions. 12 refs., 3 tabs., 12 figs.

  9. Amperometric sensing of nitrite using a glassy carbon electrode modified with a multilayer consisting of carboxylated nanocrystalline cellulose and poly(diallyldimethyl ammonium) ions in a PEDOT host

    International Nuclear Information System (INIS)

    Xu, Guiyun; Liang, Shaoping; Sheng, Ge; Luo, Xiliang; Fan, Jinshi

    2016-01-01

    Negatively charged carboxylated nanocrystalline cellulose (CNCC) and positively charged poly(diallyldimethyl ammonium chloride) (PDDA) were alternatingly assembled on the surface of a glassy carbon electrode to form a relatively uniform polyelectrolyte multilayer nanocomposite (CNCC/PDDA)n. It was then incorporated into a matrix of conducting poly(3,4-ethylenedioxythiophene) (PEDOT) electrodeposited on the surface of the electrode. The nanocomposites were prepared in various ratios of PEDOT and (CNCC/PDDA), and then characterized by transmission electron microscopy, scanning electron microscopy, electrochemical impedance spectroscopy, cyclic voltammetry, and differential pulse voltammetry. The PEDOT/(CNCC/PDDA)4 nanocomposite showed the lowest electrochemical impedance and best electrocatalytic activity towards the oxidation of nitrite. Based on these findings, an amperometric sensor was developed which, if operated at 0.80 V (vs. SCE), can detect nitrite in the 0.2 μM to 1.73 mM concentration range with a 57 nM detection limit. (author)

  10. Effect of Sodium Nitrite and Sodium Nitrate on Botulinal Toxin Production and Nitrosamine Formation in Wieners

    Science.gov (United States)

    Hustad, Gerald O.; Cerveny, John G.; Trenk, Hugh; Deibel, Robert H.; Kautter, Donald A.; Fazio, Thomas; Johnston, Ralph W.; Kolari, Olaf E.

    1973-01-01

    Wieners were formulated and processed approximating commercial conditions as closely as possible. Twenty-four batches of product were made with the addition of six levels of sodium nitrite (0, 50, 100, 150, 200, and 300 μg/g), four levels of sodium nitrate (0, 50, 150, and 450 μg/g), and two levels of Clostridium botulinum (0 and 620 spores/g). After formulation, processing, and vacuum packaging, portions of each batch were incubated at 27 C or held for 21 days at 7 C followed by incubation at 27 C for 56 days. The latter storage condition approximated distribution of product through commercial channels and potential temperature abuse at the consumer level. Samples were analyzed for botulinal toxin, nitrite, and nitrate levels after 3, 7, 14, 21, 28, and 56 days of incubation. When nitrite was not added, toxic samples were detected after 14 days of incubation at 27 C. At the lowest level of nitrite added (50 μg/g), no toxic samples were observed until 56 days of incubation. Higher levels of nitrite completely inhibited toxin production throughout the incubation period. Nine uninoculated samples, representing various levels and combinations of nitrite and nitrate, were evaluated organoleptically. The flavor quality of wieners made with nitrite was judged significantly higher (P = 0.05) than of wieners made without nitrite. The nine samples were negative for 14 volatile nitrosamines at a sensitivity level of 10 ng/g. The results indicated that nitrite effectively inhibited botulinal toxin formation at commercially employed levels in wieners and that detectable quantities of nitrosamines were not produced during preparation and processing of the product for consumption. PMID:4580194

  11. Iron(II) porphyrins induced conversion of nitrite into nitric oxide: A computational study.

    Science.gov (United States)

    Zhang, Ting Ting; Liu, Yong Dong; Zhong, Ru Gang

    2015-09-01

    Nitrite reduction to nitric oxide by heme proteins was reported as a protective mechanism to hypoxic injury in mammalian physiology. In this study, the pathways of nitrite reduction to nitric oxide mediated by iron(II) porphyrin (P) complexes, which were generally recognized as models for heme proteins, were investigated by using density functional theory (DFT). In view of two type isomers of combination of nitrite and Fe(II)(P), N-nitro- and O-nitrito-Fe(II)-porphyrin complexes, and two binding sites of proton to the different O atoms of nitrite moiety, four main pathways for the conversion of nitrite into nitric oxide mediated by iron(II) porphyrins were proposed. The results indicate that the pathway of N-bound Fe(II)(P)(NO2) isomer into Fe(III)(P)(NO) and water is similar to that of O-bound isomer into nitric oxide and Fe(III)(P)(OH) in both thermodynamical and dynamical aspects. Based on the initial computational studies of five-coordinate nitrite complexes, the conversion of nitrite into NO mediated by Fe(II)(P)(L) complexes with 14 kinds of proximal ligands was also investigated. Generally, the same conclusion that the pathways of N-bound isomers are similar to those of O-bound isomer was obtained for iron(II) porphyrin with ligands. Different effects of ligands on the reduction reactions were also found. It is notable that the negative proximal ligands can improve reactive abilities of N-nitro-iron(II) porphyrins in the conversion of nitrite into nitric oxide compared to neutral ligands. The findings will be helpful to expand our understanding of the mechanism of nitrite reduction to nitric oxide by iron(II) porphyrins. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Color and oxidative stability of nitrite-free cured meat after gamma irradiation

    International Nuclear Information System (INIS)

    Shahidi, F.; Pegg, R.B.; Shamsuzzaman, K.

    1991-01-01

    The effects of 5 and 10 kGy irradiation on the color and oxidative stability of meats treated with nitrite or a nitrite-free curing system were investigated. The nitrite-free curing system consisted of the preformed cooked cured-meat pigment, sodium ascorbate and sodium tripolyphosphate with or without sodium acid pyrophosphate. Irradiation had no detrimental effects on the color or flavor of either cured samples. Polyphosphates had a beneficial effect on oxidative stability but had a slight detrimental effect on color stability of irradiated samples

  13. Role of Nitrite in Processed Meat Products and its Degradation during their Storage

    OpenAIRE

    ILIRJANA BOCI; ELDA ZIU; GENTJANA BARDHI

    2014-01-01

    This paper represents the analytical data of nitrite level obtained from the experimental work done on meat processed samples taken from a meat processing plant in Tirana. There has been a long debate and health concern about the nitrite content in meat products. Nitrite is added to e.g. sausages, and hams and other meat products to preserve these products and keep them free from dangerous bacteria. Among the aims are preventing botulism, a dangerous food poison. But also it’s important to us...

  14. Occurrence of nitrate, nitrite and volatile nitrosamines in certain feedstuffs and animal products.

    Science.gov (United States)

    Ologhobo, A D; Adegede, H I; Maduagiwu, E N

    1996-01-01

    Nitrate, nitrite and nitrosamines were analysed in poultry feeds, meat and eggs. The poultry meat was boiled and roasted while the eggs were raw and boiled, and the effects of these processing treatments on the level of these compounds were investigated. Nitrate levels in the meat samples were significantly (P Nitrite levels were also reduced significantly by processing (P Nitrite levels were generally low in all feed samples. Nitrosamines were not detected in any of the feed samples and in the meat samples except in two samples of boiled meat which contained 0.001 g/kg each.

  15. Preliminary nitrite, nitrate and colour analysis of Malaysian edible bird’s nest

    OpenAIRE

    Quek, Meei Chien; Chin, Nyuk Ling; Yusof, Yus Aniza; Tan, Sheau Wei; Law, Chung Lim

    2015-01-01

    The high nitrite content in edible bird’s nests is a major concern to the local swiftlet industry. It lowers the price of the edible bird’s nests and it brings severe health hazards to consumers and farmers. This research investigated the nitrite and nitrate contents of eight types of local edible bird’s nests by using ion chromatography system and evaluating its colour using the CIE system in L∗a∗b∗ parameters. The nitrite content obtained ranged from 5.7 μg/g for the house nests to 843.8 μg...

  16. Effects of the presence of the curing agent sodium nitrite, used in the production of fermented sausages, on bacteriocin production by Weissella paramesenteroides DX grown in meat simulation medium.

    Science.gov (United States)

    Papagianni, M; Sergelidis, D

    2013-06-10

    Weissellin A is a listericidal bacteriocin produced by the sausage-isolated strain of Weissella paramesenteroides DX. The response of the strain to various concentrations of the added curing agent NaNO2 (0.0025, 0.005 and 0.01g/L) was evaluated in bioreactor fermentations using a meat simulation medium. The presence of nitrite suppressed bacteriocin production - the effect being more pronounced with increasing concentrations. Weissellin A was produced as a growth-associated metabolite in the absence of nitrite or its presence in the low concentration of 0.005g/L under aerobic conditions. The suppressive effect of nitrite was apparent under conditions supporting increased specific production rates, e.g. 50% and 100% dissolved oxygen tension, but no effect was observed under anaerobic conditions. As the latter prevail in the microenvironment of fermented meat products, the absence of any influence of nitrite on bacteriocin production is an important finding that enlightens the role of this species of lactic acid bacteria in its common substrates. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. Acute, Sub-lethal Cyanide Poisoning in Mice is Ameliorated by Nitrite Alone: Complications Arising from Concomitant Administration of Nitrite and Thiosulfate as an Antidotal Combination

    Science.gov (United States)

    Cambal, Leah K.; Swanson, Megan R.; Yuan, Quan; Weitz, Andrew C.; Li, Hui-Hua; Pitt, Bruce R.; Pearce, Linda L.; Peterson, Jim

    2011-01-01

    Sodium nitrite alone is shown to ameliorate sub-lethal cyanide toxicity in mice when given from ~1 hour before until 20 minutes after the toxic dose as demonstrated by the recovery of righting ability. An optimum dose (12 mg/kg) was determined to significantly relieve cyanide toxicity (5.0 mg/kg) when administered to mice intraperitoneally. Nitrite so administered was shown to rapidly produce NO in the bloodsteam as judged by the dose dependent appearance of EPR signals attributable to nitrosylhemoglobin and methemoglobin. It is argued that antagonism of cyanide inhibition of cytochrome c oxidase by NO is the crucial antidotal activity rather than the methemoglobin-forming action of nitrite. Concomitant addition of sodium thiosulfate to nitrite-treated blood resulted in the detection of sulfidomethemoblobin by EPR spectroscopy. Sulfide is a product of thiosulfate hydrolysis and, like cyanide, is known to be a potent inhibitor of cytochrome c oxidase; the effects of the two inhibitors being essentially additive under standard assay conditions, rather than dominated by either one. The findings afford a plausible explanation for an observed detrimental effect in mice associated with the use of the standard nitrite-thiosulfate combination therapy at sub-lethal levels of cyanide intoxication. PMID:21534623

  18. Optimization of an Sbr process for nitrogen removal from concentrated wastewater via nitrite

    International Nuclear Information System (INIS)

    Longhi, L.; Basilico, D.; Meloni, A.; Canziani, R.

    2009-01-01

    The results of an experimentation carried out on a pilot-scale Sbr for nitrogen removal via nitridation-denitration are reported. The experimentation was carried out in the period July October 2007 and was aimed at achieving design data for the upgrade of a full scale wastewater treatment plant (WWTP), following the new regulations issued by Lombardy Regional Authority for the discharge of effluents into sensitive areas. One aspect that has been considered in the upgrade is nitrogen removal from the supernatant coming from anaerobic sludge digestion. The experimental results provided sound design data based on real biological activity measurements and operational process parameters such as oxygen and organic carbon requirements. [it

  19. Haematological and biochemical profiles of carp blood following nitrite exposure at different concentrations of chloride

    Czech Academy of Sciences Publication Activity Database

    Svobodová, Z.; Máchová, J.; Drastichová, J.; Groch, L.; Lusková, Věra; Poleszczuk, G.; Velíšek, J.; Kroupová, H.

    2005-01-01

    Roč. 36, č. 12 (2005), s. 1177-1184 ISSN 1355-557X Institutional research plan: CEZ:AV0Z60930519 Keywords : common carp * acute toxicity * gill histopathology Subject RIV: EG - Zoology Impact factor: 0.746, year: 2005

  20. Development and validation of an ionic chromatography method for the determination of nitrate, nitrite and chloride in meat.

    Science.gov (United States)

    Lopez-Moreno, Cristina; Perez, Isabel Viera; Urbano, Ana M

    2016-03-01

    The purpose of this study is to develop the validation of a method for the analysis of certain preservatives in meat and to obtain a suitable Certified Reference Material (CRM) to achieve this task. The preservatives studied were NO3(-), NO2(-) and Cl(-) as they serve as important antimicrobial agents in meat to inhibit the growth of bacteria spoilage. The meat samples were prepared using a treatment that allowed the production of a known CRM concentration that is highly homogeneous and stable in time. The matrix effects were also studied to evaluate the influence on the analytical signal for the ions of interest, showing that the matrix influence does not affect the final result. An assessment of the signal variation in time was carried out for the ions. In this regard, although the chloride and nitrate signal remained stable for the duration of the study, the nitrite signal decreased appreciably with time. A mathematical treatment of the data gave a stable nitrite signal, obtaining a method suitable for the validation of these anions in meat. A statistical study was needed for the validation of the method, where the precision, accuracy, uncertainty and other mathematical parameters were evaluated obtaining satisfactory results. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Florfenicol residues in Rainbow Trout after oral dosing in recirculating and flow-through culture systems

    Science.gov (United States)

    Meinertz, Jeffery R.; Hess, Karina R.; Bernady, Jeffry A.; Gaikowski, M. P.; Whitsel, Melissa; Endris, R. G.

    2014-01-01

    Aquaflor is a feed premix for fish containing the broad spectrum antibacterial agent florfenicol (FFC) incorporated at a ratio of 50% (w/w). To enhance the effectiveness of FFC for salmonids infected with certain isolates of Flavobacterium psychrophilum causing coldwater disease, the FFC dose must be increased from the standard 10 mg·kg−1 body weight (BW)·d−1 for 10 consecutive days. A residue depletion study was conducted to determine whether FFC residues remaining in the fillet tissue after treating fish at an increased dose would be safe for human consumption. Groups of Rainbow Trout Oncorhynchus mykiss (total n = 144; weight range, 126–617 g) were treated with FFC at 20 mg·kg−1 BW·d−1 for 10 d in a flow-through system (FTS) and a recirculating aquaculture system (RAS) each with a water temperature of ∼13°C. The two-tank RAS included a nontreated tank containing 77 fish. Fish were taken from each tank (treated tank, n = 16; nontreated tank, n = 8) at 6, 12, 24, 48, 72, 120, 240, 360, and 480 h posttreatment. Florfenicol amine (FFA) concentrations (the FFC marker residue) in skin-on fillets from treated fish were greatest at 12 h posttreatment (11.58 μg/g) in the RAS and were greatest at 6 h posttreatment (11.09 μg/g) in the FTS. The half-lives for FFA in skin-on fillets from the RAS and FTS were 20.3 and 19.7 h, respectively. Assimilation of FFC residues in the fillets of nontreated fish sharing the RAS with FFC-treated fish was minimal. Florfenicol water concentrations peaked in the RAS-treated tank and nontreated tanks at 10 h (453 μg/L) and 11 h (442 μg/L) posttreatment, respectively. Monitoring of nitrite concentrations throughout the study indicated the nitrogen oxidation efficiency of the RAS biofilter was minimally impacted by the FFC treatment.

  2. Formation of methemoglobin and metmyoglobin using 8-aminoquinoline derivatives or sodium nitrite and subsequent reaction with cyanide.

    Science.gov (United States)

    Steinhaus, R K; Baskin, S I; Clark, J H; Kirby, S D

    1990-10-01

    The kinetics of the oxidation of hemoglobin (Hb) and myoglobin (Mb) by sodium nitrite, 8-[(4-amino-1-methylbutyl)amino]-6-methoxy-quinoline diphosphate (primaquine), 6-methoxy-8-(6-diethylaminohexylamino)-4-methyl-quinoline dihydrochloride (WR6026) and 8-[(4-amino-1-methylbutyl)amino]-2,6-dimethoxy-4-methyl- 5-[(3-trifluoromethyl)phenoxy]quinoline succinate (WR238,605) were studied at pH values ranging from 7.4 to 7.6 and at 37 +/- 1 degrees C. The reaction between Hb and primaquine, WR6026 and WR238,605 resulted in precipitation, as did the reaction between Mb and WR238,605. The reaction between nitrite ion (NO2-) and Hb showed a lag period followed by an autocatalytic phase. The data in this study are consistent with and substantiate the proposed mechanism for the Hb-NO2- oxidation reaction. The reaction between Mb and NO2- at higher NO2- concentrations also showed a lag period followed by an autocatalytic period, while at lower NO2- concentrations no lag period was seen. The data suggest a shift in rate constant at these lower NO2- concentrations. The reaction between Mb and both WR6026 and primaquine followed a two-term rate law with oxidant-dependent and -independent terms. Concentration-effect curve data, along with these results, suggest the presence of a catalytic pathway. The rates of formation of cyanomethemoglobin and cyanometmyoglobin complexes from cyanide ion and methemoglobin (MHb) and metmyoglobin (MMb), respectively, were followed in the presence of the heme oxidants. The rate constants were all within a narrow range and suggest that complexation of cyanide by MHb and MMb is not affected by the presence of oxidants.

  3. Nitrite-induced enhancement of toxicity of phenanthrene in fish and its implications for coastal waters

    Digital Repository Service at National Institute of Oceanography (India)

    Shailaja, M.S.; Rodrigues, A

    Coastal areas are prone to varying degrees of anthropogenic chemical contamination. In many coastal environments experiencing reducing conditions in the water column, nitrite is produced as a result of denitrification. With a view to determining...

  4. Increased formation of carcinogenic PAH metabolites in fish promoted by nitrite

    Digital Repository Service at National Institute of Oceanography (India)

    Shailaja, M.S.; Rajamanickam, R.; Wahidullah, S.

    Nitrite (NO2−), a highly reactive chemical species, accumulates in coastal waters as a result of pollution with nitrogenous waste and/or an imbalance in the bacterial processes of nitrification and denitrification. The present study probed...

  5. Nitrite electrochemical sensor based on prussian blue/single-walled carbon nanotubes modified pyrolytic graphite electrode

    CSIR Research Space (South Africa)

    Adekunle, AS

    2011-09-01

    Full Text Available Nitrite, NO2- (in neutral), and NO (in acidic media) were used as analytical probe to investigate the electrocatalytic properties of Prussian blue nanoparticles (PB) modified edge plane pyrolytic graphite (EPPG) electrode. Results indicate...

  6. Dramatic loss of comammox Nitrospira associated with long-term nitrite feeding

    DEFF Research Database (Denmark)

    Kinnunen, Marta; Palomo, Alejandro; Dechesne, Arnaud

    Until recently, nitrification was thought to be a strict two-step process where ammonia was first oxidized to nitrite by ammonia-oxidizing bacteria and/or archaea, and subsequently to nitrate by nitrite oxidizing bacteria (NOB). Recent studies in NOB metabolism, however, have revealed that certain......, with nitrite as the main energy source. Community assembly was monitored on well-established biofilms formed on the grains of rapid sand filter (RSF) for drinking water production. RSF sand was placed in laboratory scale column bioreactors and subjected to continuous feeding of tap water spiked with NO2- (1 mg...... sequences (100% similarity to uncultured Nitrospira sp. clone KC836101 (Pester et al., 2014)). These observations indicate different behavior of Nitrospira in the absence of ammonia and point to a possible competitive advantage of canonical Nitrospira in environments where nitrite is the sole nitrogen...

  7. Nitrite Biosensing via Selective Enzymes—A Long but Promising Route

    Directory of Open Access Journals (Sweden)

    M. Gabriela Almeida

    2010-12-01

    Full Text Available The last decades have witnessed a steady increase of the social and political awareness for the need of monitoring and controlling environmental and industrial processes. In the case of nitrite ion, due to its potential toxicity for human health, the European Union has recently implemented a number of rules to restrict its level in drinking waters and food products. Although several analytical protocols have been proposed for nitrite quantification, none of them enable a reliable and quick analysis of complex samples. An alternative approach relies on the construction of biosensing devices using stable enzymes, with both high activity and specificity for nitrite. In this paper we review the current state-of-the-art in the field of electrochemical and optical biosensors using nitrite reducing enzymes as biorecognition elements and discuss the opportunities and challenges in this emerging market.

  8. Color compensation in nitrite-reduced meat batters incorporating paprika or tomato paste.

    Science.gov (United States)

    Bázan-Lugo, Eduardo; García-Martínez, Ignacio; Alfaro-Rodríguez, Rosa Hayde; Totosaus, Alfonso

    2012-06-01

    Nitrite is a key ingredient the manufacture of meat products, forming a stable pink color characteristic of cured products, retarding the development of rancidity and off-odors and flavors during storage, and preventing microbial growth. The negative aspects of nitrite and the demands for healthy foods result in the need to reduce nitrite in cured meat products. Paprika or tomato has been employed as natural pigments in meat products. The objective of this work was to determine the effect of incorporating paprika powder or tomato paste on the texture, rancidity and instrumental and sensory color compensation in nitrite-reduced meat batters. Addition of tomato paste improved moisture content, resulting in harder but less cohesive samples as compared to control and paprika-containing meat batters. Color characteristics of reduced nitrite samples obtained higher a* red coloration (8.9 for paprika and 7.7-8.0 for tomato paste), as compared to control samples (5.65). Instrumental color was low in control samples, with high values for tomato paste and paprika samples. Nonetheless, tomato paste used to compensate color in nitrite-reduced meat batters was ranked closer to the control sample in sensory evaluation. Color characteristics-instrumental and sensory-in these kinds of meat products were enhanced by the addition of 2.5-3.0% of tomato paste, presenting results close to the non-reduced nitrite control. Similarly, antioxidant components of tomato paste or paprika reduced lipid oxidation. Nitrite reduction from 150 to 100 ppm could be achieved employing tomato paste as a natural pigment to improve color and texture. Copyright © 2011 Society of Chemical Industry.

  9. Histopathological effects of sodium nitrite on the spleen of male and female rats

    Directory of Open Access Journals (Sweden)

    Fateme Juibar

    2015-01-01

    Full Text Available Background: Nitrite and nitrate are common additives in meat processed products. In spite of all technological advantages of nitrite, creation of nitrosamine carcinogenic substances causes a lot of concerns for use of these additives. In this study, the histopatological effects of sodium nitrite on the splenic tissue in adult male and female rats were evaluated. Material and method: In recent studies, 60 adult male and female rats strain Vistar, divided in 6 groups of 10. They were examined for 60 day, and they (male and female rats separately were divided in 175 mg/kg/day dose recipient group, 350 mg/kg/day dose recipient group and control group which was absorbed nitrite through drinking water. At the end of day 60, using cotton dipped in ether in the jar of anesthesia, were anesthetized. After anesthesia, blood from the left ventricle was taken .the spleen was taking out of body, and then tissue sections were prepared for testing tissue changes. The samples were stained with Hematoxilin- Eozin method. In both sex, factors like morphometric and morphologic from spleen tissue, body weight changes before and after test and blood NOx level was checked. After data collection, all data was analyzed by SPSS statistical software version 17 with using Independent sample t-test and ANOVA. P value of less than 0.05 were reported as statistically significant. Result: The results showed that consume of sodium nitrite, cause background inflammation type of Mononuclear in both sex, especially around the pulp. Also, in both sex NOx levels in the blood of animals in the group receiving 350 mg/ kg and group receiving 175 mg of sodium nitrite per kg compared with the control group, significantly increased (p ≤ 0.05. Conclusion: Considering of this study and other studies, Nitrite can cause damage to blood vessels, liver, spleen and other organs. Also sodium nitrite has to switching to other food preservatives.

  10. Some observations concerning the direct titration of nitrite with cerium(IV)

    International Nuclear Information System (INIS)

    Muralikrishna, U.; Subrahmanyam, K.; Suryanarayana, M.V.S.; Krishnamurthy, M.

    1983-01-01

    Direct titration of nitrite with cerium(IV), with ferroin as indicator, is shown to give satisfactory results if the acidity is kept between 0.033 and 0.055 M at the end-point. Loss of nitrous acid owing to volatilization and decomposition is discussed. From 10 to 60 mg of sodium nitrite can be estimated with a standard deviation of 5 μg and an average error of 0.2%. (author)

  11. Protection of Steel Corrosion in Concrete Members by the Combination of Galvanic Anode and Nitrite Penetration

    Directory of Open Access Journals (Sweden)

    Minobu Aoyama

    2014-01-01

    Full Text Available Chloride induced-corrosion of steel bars in concrete can make cracks and exfoliation in near-surface regions in reinforced concrete structures. In this paper, we described the basic concept and practice of steel bars corrosion protection method by the combination of galvanic anode (zinc wire and the penetration of nitrite ions from mortar layers containing a large amount of lithium nitrite.

  12. [Poppers at top: alkyl nitrites use in France].

    Science.gov (United States)

    Beck, François; Guignard, Romain; Richard, Jean-Baptiste

    2014-10-01

    Poppers is the usual name of various forms of alkyl nitrites. They are used as recreational drugs to intensify sexual intercourses and provoke a short euphoria just after their inhalation. In spite of several periods of ban in the 2000s, poppers' use sharply rose between 2000 and 2010. In the adult population as in teenagers, it is the second product consumed after cannabis among illicit drugs, confirming that it concerns circles wider than gays and lesbians who are sometimes depicted as emblematic users. The lifetime use of poppers concerns 5.3% of 18-64 years in 2010, men (7.2%) more than women (3.4%). At the end of the adolescence, its lifetime prevalence is 8.8% for girls and 9.2% for boys. In the general population and especially among young people, poppers is favourably considered. Nevertheless, this product is not without danger, even if the risk of dependence is extremely low. Several avenues of interventions may be outlined, mainly based on information and a regular follow-up of users which can allow to avoid an intensification of the consumption. © 2014 médecine/sciences – Inserm.

  13. Analysis of nitrates and nitrites in subsoil and ground water samples in Swaziland

    Directory of Open Access Journals (Sweden)

    A.O. Fadiran

    2005-06-01

    Full Text Available The concentrations of nitrate as nitrogen (NO3–N in mg/L and nitrite as nitrogen (NO2–N in µg/L were determined in water samples from 60 boreholes, 21 shallow wells and 7 springs located in the four regions of the country. For all the 88 sampling points nitrate levels vary within 0.05 plus or minus 0.00 – 28.44 plus or minus 0.80 mg/L NO3–N, out of which 10.22% have mg/L NO3–N ≥ MCL (maximum contaminant level of 10 mg/L NO3–N. Shallow wells recorded the highest NO3–N% ≥ MCL of 20.0% followed by boreholes with NO3–N % ≥ MCL of 8.33% while for springs, the NO3–N % ≥ MCL was zero. On the other hand, NO2–N (μg/L from all the sampling points vary within (ND/0.30 plus or minus 0.00 – 297.0 plus or minus 0.50 μg/L NO2–N, which were far below the recommended MCL of 1 mg/L (= 1000 μg/L.

  14. Nitrous Oxide Production in a Granule-based Partial Nitritation Reactor: A Model-based Evaluation.

    Science.gov (United States)

    Peng, Lai; Sun, Jing; Liu, Yiwen; Dai, Xiaohu; Ni, Bing-Jie

    2017-04-03

    Sustainable wastewater treatment has been attracting increasing attentions over the past decades. However, the production of nitrous oxide (N 2 O), a potent GHG, from the energy-efficient granule-based autotrophic nitrogen removal is largely unknown. This study applied a previously established N 2 O model, which incorporated two N 2 O production pathways by ammonia-oxidizing bacteria (AOB) (AOB denitrification and the hydroxylamine (NH 2 OH) oxidation). The two-pathway model was used to describe N 2 O production from a granule-based partial nitritation (PN) reactor and provide insights into the N 2 O distribution inside granules. The model was evaluated by comparing simulation results with N 2 O monitoring profiles as well as isotopic measurement data from the PN reactor. The model demonstrated its good predictive ability against N 2 O dynamics and provided useful information about the shift of N 2 O production pathways inside granules for the first time. The simulation results indicated that the increase of oxygen concentration and granule size would significantly enhance N 2 O production. The results further revealed a linear relationship between N 2 O production and ammonia oxidation rate (AOR) (R 2  = 0.99) under the conditions of varying oxygen levels and granule diameters, suggesting that bulk oxygen and granule size may exert an indirect effect on N 2 O production by causing a change in AOR.

  15. Enhanced Activity and Selectivity of Carbon Nanofiber Supported Pd Catalysts for Nitrite Reduction

    KAUST Repository

    Shuai, Danmeng; Choe, Jong Kwon; Shapley, John R.; Werth, Charles J.

    2012-01-01

    Pd-based catalyst treatment represents an emerging technology that shows promise to remove nitrate and nitrite from drinking water. In this work we use vapor-grown carbon nanofiber (CNF) supports in order to explore the effects of Pd nanoparticle size and interior versus exterior loading on nitrite reduction activity and selectivity (i.e., dinitrogen over ammonia production). Results show that nitrite reduction activity increases by 3.1-fold and selectivity decreases by 8.0-fold, with decreasing Pd nanoparticle size from 1.4 to 9.6 nm. Both activity and selectivity are not significantly influenced by Pd interior versus exterior CNF loading. Consequently, turnover frequencies (TOFs) among all CNF catalysts are similar, suggesting nitrite reduction is not sensitive to Pd location on CNFs nor Pd structure. CNF-based catalysts compare favorably to conventional Pd catalysts (i.e., Pd on activated carbon or alumina) with respect to nitrite reduction activity and selectivity, and they maintain activity over multiple reduction cycles. Hence, our results suggest new insights that an optimum Pd nanoparticle size on CNFs balances faster kinetics with lower ammonia production, that catalysts can be tailored at the nanoscale to improve catalytic performance for nitrite, and that CNFs hold promise as highly effective catalyst supports in drinking water treatment. © 2012 American Chemical Society.

  16. Role of nitrite, urate and pepsin in the gastroprotective effects of saliva