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Sample records for fuming nitric acid

  1. Bronchiolitis obliterans organizing pneumonia following nitric acid fume exposure.

    Science.gov (United States)

    Lee, L T; Ho, C H B; Putti, T C

    2014-03-01

    We describe a patient with clinical, radiological and pathological features of bronchiolitis obliterans organizing pneumonia. Investigation showed that this was likely to have been a delayed consequence of inhalation of nitric acid fumes (containing nitrogen dioxide) after a fire. This case shows that thorough investigation of the aetiology is important not only in clinical management but also in ensuring patients benefit from appropriate work injury compensation.

  2. Rocket Performance of Red Fuming Nitric Acid with Blends of Norbornadiene, Carene and Cardanol

    Directory of Open Access Journals (Sweden)

    R. Chhibber

    1992-07-01

    Full Text Available The fuel blends of nornornadiene and carene (50:50 by weight and norbornadiene, carene and cardanol (40:40:20 by weight exhibit synergistic hypergolic ignition with red fuming nitric acid (RFNA as oxidiser. These fuel blends have been evaluated by theoretical calculations of performance parameters and subsequently verified by static firing in a 10 kg/sub f/ thruster at a chamber pressure of around 20 atm, using RFNA (with 21 per cent N/sub 2/O/sub 4/ by weight as oxidiser. The theoretical calculations show maximum specific impulse and C*values at the O/F, 3 to be 227.8 s and 1598.7 m/s respectively for the norbornadiene-carene blend. The corresponding values for the norbornadiene, carene and cardanol blend were found to be 226.8 s and 1586.0 m/s respectively at the O/F, 4. For theoretical calculations, the chamber pressure (P/sub c and the exit pressure (P/sub e/0 were assumed to be 20 and 1 atm, respectively. The static firing of the propellants in a 10 kg thruster exhibited smooth pressure-time curves with the experimental C* values in close agreement with those calculated and the non-deposition of carbon in the nozzle. This indicated low combustion instability and high combustion efficiency under rocket conditions (> 0.9. The fuel blends with their low cost and toxicity and relatively high density can replace G-fuel used in several Indian missiles without impairing the performance.

  3. Design and Testing of Lab-scale Red Fuming Nitric Acid/Hydroxyl-terminated Polybutadiene Hybrid Rocket Motor for Studying Regression Rate

    Directory of Open Access Journals (Sweden)

    Sankaran Venugopal

    2011-10-01

    Full Text Available This paper presents the design of a hybrid rocket motor and the experiments carried out for investigation of hybrid combustion and regression rates for a combination of liquid oxidiser red fuming nitric acid with solid fuel hydroxyl-terminated Polybutadiene. The regression rate is enhanced with the addition of small quantity of solid oxidiser ammonium perchlorate in the fuel. The characteristics of the combustion products were calculated using the NASA CEA Code and were used in a ballistic code developed for predicting the performance of the hybrid rocket motor. A lab-scale motor was designed and the oxidiser mass flow requirements of the hybrid motor for the above combination of fuel and oxidiser have been calculated using the developed ballistic code. A static rocket motor testing facility has been realised for conducting the hybrid experiments. A series of tests were conducted and proper ignition with stable combustion in the hybrid mode has been established. The regression rate correlations were obtained as a function of the oxidiser mass flux and chamber pressure from the experiments for the various combinations.Defence Science Journal, 2011, 61(6, pp.515-522, DOI:http://dx.doi.org/10.14429/dsj.61.873

  4. 49 CFR 173.158 - Nitric acid.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Nitric acid. 173.158 Section 173.158... Nitric acid. (a) Nitric acid exceeding 40 percent concentration may not be packaged with any other material. (b) Nitric acid in any concentration which does not contain sulfuric acid or hydrochloric acid as...

  5. Alternative to Nitric Acid Passivation

    Science.gov (United States)

    Kessel, Kurt R.

    2016-01-01

    Corrosion is an extensive problem that affects the National Aeronautics and Space Administration (NASA) and European Space Agency (ESA). The deleterious effects of corrosion result in steep costs, asset downtime affecting mission readiness, and safety risks to personnel. It is vital to reduce corrosion costs and risks in a sustainable manner. The primary objective of this effort is to qualify citric acid as an environmentally-preferable alternative to nitric acid for passivation of stainless steel alloys.

  6. The Oxidation of Hydrazine by Nitric Acid

    Energy Technology Data Exchange (ETDEWEB)

    Karraker, D.G.

    2001-07-02

    Hydrazine nitrate-nitric acid solutions are used in the ion exchange process for separating Pu-238 and Np-237 and have been found to dissolve plutonium metal in a manner advantageous to SRP metal recovery operations. Laboratory tests on the stability of hydrazine in nitric acid solutions were performed to obtain accurate data, and the results of these tests are reported here. These tests provide sufficient information to specify temperature control for hydrazine-nitric acid solutions in plant processes.

  7. Blunted behavioral and c Fos responses to acidic fumes in the African naked mole-rat.

    Directory of Open Access Journals (Sweden)

    Pamela Colleen LaVinka

    Full Text Available Acidosis in the skin triggers activation of pain pathways and behaviors indicative of pain in vertebrates. The exception is the naked mole-rat, the only known vertebrate to show physiological and behavioral insensitivity to acid pain in the skin. The goal of the present study was to determine behavioral and physiological responses of this species to airborne acidic fumes, which would be expected to affect the trigeminal pain pathway in other species. Behaviorally, naked mole-rats did not avoid fumes from moderately high concentrations of acetic acid (10 and 20%, and c Fos labeling showed no increase in activity in the trigeminal nuclei and nucleus tractus solitarius. In contrast, these concentrations triggered behavioral aversion and increased Fos activity in other laboratory rodents. For a very high concentration of acetic acid (50%, naked mole-rats showed significant avoidance behavior and increased Fos labeling in the nucleus tractus solitarius caudal region, which receives vagal chemosensory information. However, there was no increase in trigeminal labeling, and in fact, activity significantly decreased. This pattern is opposite of that associated with another irritant, ammonia fumes, which elicited an increase in trigeminal but not nucleus tractus solitarius Fos labeling, and no behavioral avoidance. Behavioral avoidance of acidic fumes, but no increased labeling in the trigeminal pain nucleus is consistent with the notion of adaptations to blunt acid pain, which would be advantageous for naked mole-rats as they normally live under chronically high levels of acidosis-inducing CO(2.

  8. Global metabolomic profiling reveals an association of metal fume exposure and plasma unsaturated fatty acids.

    Directory of Open Access Journals (Sweden)

    Yongyue Wei

    Full Text Available BACKGROUND: Welding-associated air pollutants negatively affect the health of exposed workers; however, their molecular mechanisms in causing disease remain largely unclear. Few studies have systematically investigated the systemic toxic effects of welding fumes on humans. OBJECTIVES: To explore the effects of welding fumes on the plasma metabolome, and to identify biomarkers for risk assessment of welding fume exposure. METHODS: The two-stage, self-controlled exploratory study included 11 boilermakers from a 2011 discovery panel and 8 boilermakers from a 2012 validation panel. Plasma samples were collected pre- and post-welding fume exposure and analyzed by chromatography/mass spectrometry. RESULTS: Eicosapentaenoic or docosapentaenoic acid metabolic changes post-welding were significantly associated with particulate (PM2.5 exposure (p<0.05. The combined analysis by linear mixed-effects model showed that exposure was associated with a statistically significant decline in metabolite change of eicosapentaenoic acid [β(95% CI = -0.013(-0.022 ≈ -0.004; p = 0.005], docosapentaenoic acid n3 [β(95% CI = -0.010(-0.018 ≈ -0.002; p = 0.017], and docosapentaenoic acid n6 [β(95% CI = -0.007(-0.013 ≈ -0.001; p = 0.021]. Pathway analysis identified an association of the unsaturated fatty acid pathway with exposure (p Study-2011 = 0.025; p Study-2012 = 0.021; p Combined = 0.009. The functional network built by these fatty acids and their interactive genes contained significant enrichment of genes associated with various diseases, including neoplasms, cardiovascular diseases, and lipid metabolism disorders. CONCLUSIONS: High-dose exposure of metal welding fumes decreases unsaturated fatty acids with an exposure-response relationship. This alteration in fatty acids is a potential biological mediator and biomarker for exposure-related health disorders.

  9. Alternative to Nitric Acid Passivation

    Science.gov (United States)

    Kessel, Kurt R.

    2015-01-01

    The Ground Systems Development and Operations (GSDO) Program at NASA John F. Kennedy Space Center (KSC), Florida, has the primary objective of modernizing and transforming the launch and range complex at KSC to benefit current and future NASA programs along with other emerging users. Described as the launch support and infrastructure modernization program in the NASA Authorization Act of 2010, the GSDO Program will develop and implement shared infrastructure and process improvements to provide more flexible, affordable, and responsive capabilities to a multi-user community. In support of NASA and the GSDO Program, the objective of this project is to qualify citric acid as an environmentally-preferable alternative to nitric acid for passivation of stainless steel alloys. This project is a direct follow-on to United Space Alliance (USA) work at KSC to optimize the parameters for the use of citric acid and verify effectiveness. This project will build off of the USA study to further evaluate citric acids effectiveness and suitability for corrosion protection of a number of stainless steels alloys used by NASA, the Department of Defense (DoD), and the European Space Agency (ESA).

  10. Citric Acid Alternative to Nitric Acid Passivation

    Science.gov (United States)

    Lewis, Pattie L. (Compiler)

    2013-01-01

    The Ground Systems Development and Operations GSDO) Program at NASA John F. Kennedy Space Center (KSC) has the primary objective of modernizing and transforming the launch and range complex at KSC to benefit current and future NASA programs along with other emerging users. Described as the launch support and infrastructure modernization program in the NASA Authorization Act of 2010, the GSDO Program will develop and implement shared infrastructure and process improvements to provide more flexible, affordable, and responsive capabilities to a multi-user community. In support of the GSDO Program, the purpose of this project is to demonstratevalidate citric acid as a passivation agent for stainless steel. Successful completion of this project will result in citric acid being qualified for use as an environmentally preferable alternative to nitric acid for passivation of stainless steel alloys in NASA and DoD applications.

  11. Electrochemical Behavior of Aluminum in Nitric Acid

    Institute of Scientific and Technical Information of China (English)

    CHEN; Hui; ZHU; Li-yang; LIN; Ru-shan; TAN; Hong-bin; HE; Hui

    2013-01-01

    Aluminum is one of cladding materials for nuclear fuel,it is important to investigate the electrolytic dissolution of aluminum in nitric acid.The electrochemical impedance spectroscopy,polarization curve and cyclic voltammetry cure of anodic aluminum electrode in nitric acid under various conditions were collected(Fig.1).It turns out,under steady state,the thickness of the passivated film of aluminum

  12. Alternative to Nitric Acid Passivation Project Overview

    Science.gov (United States)

    Lewis, Pattie L.

    2013-01-01

    The standard practice for protection of stainless steel is a process called passivation. This procedure results in the formation of a metal oxide layer to prevent corrosion. Typical passivation procedures call for the use of nitric acid which exhibits excellent corrosion performance; however, there are a number of environmental, worker safety, and operational issues associated with its use. The longtime military specification for the passivation of stainless steel was cancelled in favor of newer specifications which allow for the use of citric acid in place of nitric acid. Citric acid offers a variety of benefits that include increased safety for personnel, reduced environmental impact, and reduced operational costs. There have been few studies, however, to determine whether citric acid is an acceptable alternative for NASA and DoD. This paper details activities to date including development of the joint test plan, on-going and planned testing, and preliminary results.

  13. Speciation in aqueous solutions of nitric acid.

    Science.gov (United States)

    Hlushak, S; Simonin, J P; De Sio, S; Bernard, O; Ruas, A; Pochon, P; Jan, S; Moisy, P

    2013-02-28

    In this study, speciation in aqueous solutions of nitric acid at 25 °C was assessed in two independent ways. First, Raman experiments were carried out and interpreted in terms of free nitrate ions, ion pairs and neutral HNO(3) molecules. In parallel, a model was developed to account for the formation of these two kinds of pairs. It was based on an extension of the binding mean spherical approximation (BiMSA), or associative MSA (AMSA), in which the size and the charge of the ions in the chemical pair may differ from those of the free ions. A simultaneous fit of the osmotic coefficient and of the proportion of free ions (obtained from Raman spectroscopy experiments) led to an estimation of the speciation in nitric acid solutions. The result obtained using this procedure was compared with the estimation obtained from the Raman experiments.

  14. Metastable Nitric Acid Trihydrate in Ice Clouds

    Science.gov (United States)

    Weiss, Fabian; Kubel, Frank; Gálvez, Oscar; Hölzel, Markus; Parker, Stewart F.; Baloh, Philipp; Iannarelli, Riccardo; Rossi, Michel J.; Grothe, Hinrich

    2016-04-01

    The composition of high altitude ice clouds is still a matter of intense discussion. The constituents in question are ice and nitric acid hydrates. The identification and formation mechanisms, however, are still unknown but are essential to understand atmospheric processing such as the seasonal ozone depletion in the lower polar stratosphere or the radiation balance of planet Earth. We found conclusive evidence for a long-predicted phase, which has been named alpha nitric acid trihydrate (alpha-NAT). This phase has been proven by combination of X-ray and neutron diffraction experiments allowing a convincing structure solution. Additionally, vibrational spectra (infrared and inelastic neutron scattering) were recorded and compared with theoretical calculations. A strong affinity between water ice and alpha-NAT has been found, which explains the experimental spectra and the phase transition kinetics essential for identification in the atmosphere. On the basis of our results, we propose a new three-step mechanism for NAT-formation in high altitude ice clouds. F. Weiss et al. Angew. Chem. Int. Ed. 2016, accepted, DOI:10.1002/anie.201510841

  15. EFFECTS OF NITRIC ACID ON CRITICALITY SAFETY ANALYSIS

    Energy Technology Data Exchange (ETDEWEB)

    Williamson, B.

    2011-08-18

    As nitric acid molarity is increased, there are two competing phenomena affecting the reactivity of the system. First, there is interaction between each of the 10 wells in the basket-like insert. As the molarity of the nitric acid solution is increased (it moves from 100% water to 100% HNO{sub 3}), the hydrogen atom density decreases by about 80%. However, it remains a relatively efficient moderator. The moderating ratio of nitric acid is about 90% that of water. As the media between the wells is changed from 100% water to 100% nitric acid, the density of the media increases by 50%. A higher density typically leads to a better reflector. However, when the macroscopic scattering cross sections are considered, nitric acid is a much worse reflector than water. The effectiveness of nitric acid as a reflector is about 40% that of water. Since the media between the wells become a worse reflector and still remains an effective moderator, interaction between the wells increases. This phenomenon will cause reactivity to increase as nitric acid molarity increases. The seond phenomenon is due to the moderating ratio changing in the high concentration fissile-nitric acid solution in the 10 wells. Since the wells contain relatively small volumes of high concentration solutions, a small decrease in moderating power has a large effect on reactivity. This is due to the fact that neutrons are more likely to escape the high concentration fissile solution before causing another fission event. The result of this phenomenon is that as nitric acid molarity increases, reactivity decreases. Recent studies have shown that the second phenomenon is indeed the dominating force in determining reactivity changes in relation to nitric acid molarity changes. When considering the system as a whole, as nitric acid molarity increases, reactivity decreases.

  16. Adverse experiences with nitric acid at the Savannah River Site

    Energy Technology Data Exchange (ETDEWEB)

    Durant, W.S.; Craig, D.K.; Vitacco, M.J.; McCormick, J.A.

    1991-06-01

    Nitric acid is used routinely at the Savannah River Site (SRS) in many processes. However, the site has experienced a number of adverse situations in handling nitric acid. These have ranged from minor injuries to personnel to significant explosions. This document compiles many of these events and includes discussions of process upsets, fires, injuries, and toxic effects of nitric acid and its decomposition products. The purpose of the publication is to apprise those using the acid that it is a potentially dangerous material and can react in many ways as demonstrated by SRS experience. 10 refs.

  17. Corrosion studies in fuel element reprocessing environments containing nitric acid

    Energy Technology Data Exchange (ETDEWEB)

    Beavers, J A; White, R R; Berry, W E; Griess, J C

    1982-04-01

    Nitric acid is universally used in aqueous fuel element reprocessing plants; however, in the processing scheme being developed by the Consolidated Fuel Reprocessing Program, some of the equipment will be exposed to nitric acid under conditions not previously encountered in fuel element reprocessing plants. A previous report presented corrosion data obtained in hyperazeotropic nitric acid and in concentrated magnesium nitrate solutions used in its preparation. The results presented in this report are concerned with the following: (1) corrosion of titanium in nitric acid; (2) corrosion of nickel-base alloys in a nitric acid-hydrofluoric acid solution; (3) the formation of Cr(VI), which enhances corrosion, in nitric acid solutions; and (4) corrosion of mechanical pipe connectors in nitric acid. The results show that the corrosion rate of titanium increased with the refreshment rate of boiling nitric acid, but the effect diminished rapidly as the temperature decreased. The addition of iodic acid inhibited attack. Also, up to 200 ppM of fluoride in 70% HNO/sub 3/ had no major effect on the corrosion of either titanium or tantalum. In boiling 8 M HNO/sub 3/-0.05 M HF, Inconel 671 was more resistant than Inconel 690, but both alloys experienced end-grain attack. In the case of Inconel 671, heat treatment was very important; annealed and quenched material was much more resistant than furnace-cooled material.The rate of oxidation of Cr(III) to Cr(VI) increased significantly as the nitric acid concentration increased, and certain forms of ruthenium in the solution seemed to accelerate the rate of formation. Mechanical connectors of T-304L stainless steel experienced end-grain attack on the exposed pipe ends, and seal rings of both stainless steel and a titanium alloy (6% Al-4% V) underwent heavy attack in boiling 8 M HNO/sub 3/.

  18. A Simple, Transparent Fume Hood

    Science.gov (United States)

    Fredericks, John

    1998-10-01

    An inexpensive transparent fume hood can be constructed from a clear-plastic two-liter soft drink bottle that is cut just above the base. A length of vacuum tubing is secured to the opening of the bottle using black electrical tape. The tubing is then connected to a water aspirator. Beakers or flasks easily fit inside the bottle, and the bottle may be secured with a clamp and ring stand for added stability. This device has been used to collect the noxious NO2 gas generated from the reaction of copper metal with nitric acid. It also may be used in the collection of other gases. It should not be used to collect gases that are not water-soluble or in experiments that involve open flames.

  19. Nitric acid vapor removal by activated, impregnated carbons

    Energy Technology Data Exchange (ETDEWEB)

    Wood, G.O.

    1996-12-31

    Laboratory and industrial workers can be exposed to vapors of nitric acid, especially in accidents, such as spills. Nitric acid can also be a product of incineration for energy production or waste (e.g., CW agent) disposal. Activated carbons containing impregnants for enhancing vapor and gas removal have been tested for effectiveness in removing vapors of nitric acid from air. The nitric acid vapor was generated from concentrated acid solutions and detected by trapping in a water bubbler for pH measurements. Both low and moderate relative humidity conditions were used. All carbons were effective at vapor contact times representative of air-purifying respirator use. One surprising observation was the desorption of low levels of ammonia from impregnated carbons. This was apparently due to residual ammonia from the impregnation processes.

  20. Diamagnetism and Strucure of Nitric Acid-Treated Bulk Polyethylene

    OpenAIRE

    Ania, F.; Baltá Calleja, F. J.; Cagiao, M.E.

    1982-01-01

    An alternative procedure to examine the nature of the end product of nitric-acid-treated bulk polyethylene involving the measurement of the diamagnetic susceptibility is reported. This simple non-destructive method complements previous results obtained by means of IR spectroscopy. Thus after selectively removing the surface layer of the polyethylene lamellae with nitric acid (t > 50h) the diamagnetic susceptibility substantially decreases to values wich are consistent with tilted paraff...

  1. Acute chemical pneumonitis caused by nitric acid inhalation: case report

    Energy Technology Data Exchange (ETDEWEB)

    Choe, Hyung Shim; Lee, In Jae; Ko, Eun Young; Lee, Jae Young; Kim, Hyun Beom; Hwang, Dae Hyun; Lee, Kwan Seop; Lee, Yul; Bae, Sang Hoon [Hallym University Sacred Heart Hospital, Anyang (Korea, Republic of)

    2003-06-01

    Chemical pneumonitis induced by nitric acid inhalation is a rare clinical condition. The previously reported radiologic findings of this disease include acute permeability pulmonary edema, delayed bronchiolitis obliterans, and bronchiectasis. In very few published rare radiologic reports has this disease manifested as acute alveolar injury; we report a case of acute chemical pneumonitis induced by nitric acid inhalation which at radiography manifested as bilateral perihilar consolidation and ground-glass attenuation, suggesting acute alveolar injury.

  2. Photochemical reactions of neptunium in nitric acid solution containing photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Fukasawa, Tetsuo; Kawamura, Fumio (Hitachi Ltd., Ibaraki (Japan). Energy Research Lab.)

    1991-01-01

    Photochemical oxidation and reduction behaviors of neptunium were preliminarily investigated in 3 mol/l nitric acid solution. Nitric acid of 3 mol/l simulated the high level waste solution from a spent fuel reprocessing process. Concentrations of Np(V), Np(VI) and nitrous acid were determined with a photospectrometer, and solution potential with an electrode. Without additives, Np(VI) was reduced to Np(V) by nitrous acid which was photolytically generated from nitric acid. With a scavenger for nitrous acid, Np(V) was oxidized to extractable Np(VI) by a photolytically generated oxidizing reagent which were predicted by the solution potential measurement. The reduction rate was higher than the oxidation rate because of the larger quantity and higher reactivity of nitrous acid than an oxidizing reagent. Photocatalyst was proved to be effective for the oxidation of Np(V) to Np(VI). (author).

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

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, B.B.

    1995-08-01

    DOE sponsored development of the transuranium extraction (TRUEX) process for removing actinides from radioactive wastes. The solvent is a mixture of CMPO and TBP. Since the extraction characteristics of CMPO are not as well understood as those of TBP, the extraction of nitric acid, uranyl nitrate, and bismuth nitrate with CMPO (dissolved in n-dodecane) were studied. Results indicate that CMPO extracts nitric acid with a 1:1 stoichiometry; equilibrium constant is 2. 660{plus_minus}0.092 at 25 C, and extraction enthalpy is -5. 46{plus_minus}0.46 kcal/mol. Slope analysis indicates that uranyl nitrate extracts with a mixed equilibria of 1:1 and 2:1 stoichiometries in nearly equal proportion. Equil. constant of the 2: 1 extraction was 1.213 {times} 10{sup 6}{plus_minus}3.56 {times} 10{sup 4} at 25 C; reaction enthalpy was -9.610{plus_minus}0.594 kcal/mol. Nitration complexation constant is 8.412{plus_minus}0.579, with an enthalpy of -10.72{plus_minus}1.87 kcal/mol. Bismuth nitrate also extracts with a mixed equilibria of (perhaps) 1:1 and 2:1 stoichiometries. A 2:1 extraction equilibrium and a nitrate complexation adequately model the data. Kinetics and enthalpies were also measured.

  4. 发烟硫酸浓度互换公式的推导%Derivation about Concentrations Exchanging Formula of Fuming Sulphuric Acid

    Institute of Scientific and Technical Information of China (English)

    谭靖辉; 唐淑贞

    2011-01-01

    指出发烟硫酸是游离态SO3的H2SO4溶液,运用质量守恒定律对发烟硫酸浓度互换公式进行了推导,阐述了使用该公式的注意事项。%Fuming sulphuric acid was regarded as SO3 of free state in sulfuric acid solution,concentrations exchanging formula of fuming sulphuric acid was deduced by mass conservation law,attentions of formula were expounded.

  5. Nano-composite polymer gel electrolytes containing ortho-nitro benzoic acid: role of dielectric constant of solvent and fumed silica

    Science.gov (United States)

    Kumar, R.

    2015-03-01

    In this paper, nano-composite polymer gel electrolytes containing polymethylmethacrylate, dimethylacetamide, diethyl carbonate, fumed silica and ortho-nitro benzoic acid have been synthesized. Electrical conductivity, viscosity, pH and thermal behavior of these electrolytes have been studied. The effect of acid, polymer, fumed silica concentration on conductivity, pH and viscosity has been discussed. The effect of dielectric constant of solvent on conductivity behavior of composite polymer gel electrolytes has also been studied. Two maxima in conductivity behavior have been observed with fumed silica concentration for composite polymer gel electrolytes, which have been explained on the basis of double percolation threshold model. Maximum conductivity of 3.20 × 10-4 and 2.46 × 10-6 S/cm at room temperature has been observed for nano-composite polymer gel electrolytes containing 10 wt% polymethylmethacrylate in 1 M solution of o-nitro benzoic acid in dimethylacetamide and diethyl carbonate respectively. The intensity of first maximum observed in conductivity at low concentration of fumed silica has been found to decrease with the decrease in acid concentration for composite polymer gel electrolytes, while the intensity of second maximum at higher fumed silica concentration remains unaffected. The conductivity of composite gels does not show much change in the temperature range of 20-100 °C and also remains constant with time, making them suitable for use as electrolytes in various devices like fuel cells, proton batteries, electrochromic window applications etc.

  6. Characterisation of fume from hyperbaric welding operations

    Energy Technology Data Exchange (ETDEWEB)

    Ross, John A S; Semple, Sean [Environmental and Occupational Medicine, University of Aberdeen (United Kingdom); Duffin, Rodger [ELEGI Colt Laboratory, University of Edinburgh (United Kingdom); Kelly, Frank [Lung Biology Group, Kings College, University of London (United Kingdom); Seldmann, Joerg; Raab, Andrea, E-mail: j.a.ross@abdn.ac.u [Trace Element Speciation Laboratory, University of Aberdeen (United Kingdom)

    2009-02-01

    We report preliminary work characterising dust from hyperbaric welding trials carried out at increased pressure in a helium and oxygen atmosphere. Particle size and concentration were measured during welding. Samples for quartz and metal analysis and toxicity assessment were taken from a filter in the local fume extraction system. The residue of dust after metal extraction by nitric acid in hydrogen peroxide predominantly a non-metallic white powder assumed to be dust from welding rod coatings and thermal insulation material. Metallic analysis showed predominantly calcium, from the welding rod coating, and period 4 transition metals such as iron, manganese, magnesium and titanium (inductively coupled mass spectrometry, Agilent 7500c). The presence of zirconium indicated a contribution from grinding. The fume was nanoparticulate in nature with a mean particle diameter of 20-30 nm (MSI Inc WPS 1000XP). It showed an intermediate level of oxidative potential regarding the low-molecular weight respiratory tract lining fluid antioxidants ascorbate and glutathione and caused release of the inflammatory marker IL-8 in a human lung A 549 epithelial cell culture with no indication of cytotoxicity. The study findings have strong implications for the measurement techniques needed to assess fume exposure in hyperbaric welding and the provision of respiratory protection.

  7. Violent explosion after inadvertent mixing of nitric acid and isopropanol – Review 15 years later finds basic accident data corrupted, no evidence of broad learning

    DEFF Research Database (Denmark)

    Hedlund, Frank Huess; Folmer Nielsen, Merete; Hagen Mikkelsen, Sonja

    2014-01-01

    steel tank disintegrated with such force that fragments lodged in walls of concrete. The explosion ravaged the cellar, destroyed equipment, blew out a masonry wall and released large amounts of nitrous oxide fumes. Likely, 62% nitric acid (CAS 7697-37-2) and isopropanol (2-propanol, CAS 67-63-0) reacted...... the brewery to court for negligence, they did not report or investigate the accident, or attempt to disseminate information available to them. Today, the general literature is silent on the explosion hazards of mixing the two chemicals. The paper argues that without institutional support, learning...

  8. Simulated dry deposition of nitric acid near forest edges

    NARCIS (Netherlands)

    DeJong, JJM; Klaassen, W; Jong, J.J.M. de

    1997-01-01

    Dry deposition is simulated to understand and generalize observations of enhanced deposition of air pollution near forest edges. Nitric acid is taken as an example as its deposition velocity is often assumed to be determined by turbulent transport only. The simulations are based on the micro-meteoro

  9. REACTIVITY OF RESORCINOL FORMALDEHYDE RESIN WITH NITRIC ACID

    Energy Technology Data Exchange (ETDEWEB)

    King, W; Fernando Fondeur, F; Bill Wilmarth, B; Myra Pettis, M; Shirley Mccollum, S

    2006-06-14

    Solid-state infrared spectroscopy, differential scanning calorimetry, and elemental analysis have been used to evaluate the reactivity of resorcinol formaldehyde resin with nitric acid and characterize the solid product. Two distinct reactions were identified within the temperature range 25-55 C. The first reaction is primarily associated with resin nitration, while the second involves bulk oxidation and degradation of the polymer network leading to dissolution and off-gassing. Reaction was confirmed with nitric acid concentrations as low as 3 M at 25 C applied temperature and 0.625 M at 66 C. Although a nitrated resin product can be isolated under appropriate experimental conditions, calorimetry testing indicates no significant hazard associated with handling the dry material.

  10. Reactivity of Resorcinol Formaldehyde Resin with Nitric Acid

    Energy Technology Data Exchange (ETDEWEB)

    King, William D.; Fondeur, Fernando F.; Wilmarth, William R.; Pettis, Myra E.

    2005-10-25

    Solid-state infrared spectroscopy, differential scanning calorimetry, and elemental analysis have been used to evaluate the reactivity of resorcinol formaldehyde resin with nitric acid and characterize the solid product. Two distinct reactions were identified within the temperature range 25-55 C. The first reaction is primarily associated with resin nitration, while the second involves bulk oxidation and degradation of the polymer network leading to dissolution and off-gassing. The threshold conditions promoting reaction have been identified. Reaction was confirmed with nitric acid concentrations as low as 3 M at 25 C applied temperature and 0.625 M at 66 C. Although a nitrated resin product can be isolated under appropriate experimental conditions, calorimetry testing indicates no significant hazard associated with handling the dry material.

  11. Nitric acid trihydrate (NAT) in polar stratospheric clouds.

    Science.gov (United States)

    Voigt, C; Schreiner, J; Kohlmann, A; Zink, P; Mauersberger, K; Larsen, N; Deshler, T; Kröger, C; Rosen, J; Adriani, A; Cairo, F; Di Donfrancesco, G; Viterbini, M; Ovarlez, J; Ovarlez, H; David, C; Dörnbrack, A

    2000-12-01

    A comprehensive investigation of polar stratospheric clouds was performed on 25 January 2000 with instruments onboard a balloon gondola flown from Kiruna, Sweden. Cloud layers were repeatedly encountered at altitudes between 20 and 24 kilometers over a wide range of atmospheric temperatures (185 to 197 kelvin). Particle composition analysis showed that a large fraction of the cloud layers was composed of nitric acid trihydrate (NAT) particles, containing water and nitric acid at a molar ratio of 3:1; this confirmed that these long-sought solid crystals exist well above ice formation temperatures. The presence of NAT particles enhances the potential for chlorine activation with subsequent ozone destruction in polar regions, particularly in early and late winter.

  12. About safety technology of cleaning tank storing fuming sulphuric acid%发烟硫酸贮罐清洗安全技术

    Institute of Scientific and Technical Information of China (English)

    彭友德

    2001-01-01

    To take the safety measures according to conclusion of analysis accident hidden danger, to clean successfully the tank storing fuming sulphuric acid on neutralization, then to put forward the improving measures.%根据事故隐患分析,采取安全措施,成功地用中和法清洗发烟硫酸贮罐,并提出了贮罐的改进措施。

  13. STUDIES ON THE RING-OPENING POLYMERIZATION OF TETRAHYDROFURAN Ⅳ. COPOLYMERIZATION OF TETRAHYDROFURAN AND PROPYLENE OXIDE INITIATED BY FUMING SULFURIC ACID AND PERCHLORIC ACID CATALYST SYSTEM

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hongzhi; GAO Guozhen; WANG Yin; FENG Xinde(S. T. Voong)

    1983-01-01

    The yield of copolymerization of tetrahydrofuran and propylene oxide (THF: PO = 100: 5-15, by wt) using a binary catalyst of fuming sulfuric acid (21% or 28%) and perchloric acid is around 50-60%, and the loss of THF in the reaction is below 10-15%. The average molecular weight of the product can be controlled in the range of 1000-2000 by varying the binary catalyst system.The present method, which is different from the usual copolymerization initiated by BF3-diol or SbCl5-diol system, shows the pecularities i.e. the yield of copolymerization with the low PO feed is not decreased, the hydroxyl functionality is equal to 2, and the end-groups are predominantly primary hydroxyls (around 65-70%).

  14. Alternative to Nitric Acid for Passivation of Stainless Steel Alloys

    Science.gov (United States)

    Lewis, Pattie L.; Kolody, Mark; Curran, Jerry

    2013-01-01

    Corrosion is an extensive problem that affects the Department of Defense (DoD) and National Aeronautics and Space Administration (NASA). The deleterious effects of corrosion result in steep costs, asset downtime affecting mission readiness, and safety risks to personnel. Consequently, it is vital to reduce corrosion costs and risks in a sustainable manner. The DoD and NASA have numerous structures and equipment that are fabricated from stainless steel. The standard practice for protection of stainless steel is a process called passivation. Typical passivation procedures call for the use of nitric acid; however, there are a number of environmental, worker safety, and operational issues associated with its use. Citric acid offers a variety of benefits including increased safety for personnel, reduced environmental impact, and reduced operational cost. DoD and NASA agreed to collaborate to validate citric acid as an acceptable passivating agent for stainless steel. This paper details our investigation of prior work developing the citric acid passivation process, development of the test plan, optimization of the process for specific stainless steel alloys, ongoing and planned testing to elucidate the process' resistance to corrosion in comparison to nitric acid, and preliminary results.

  15. Physical, Mechanical, and Thermal Analysis of Polylactic Acid/Fumed Silica/Clay (1.28E Nanocomposites

    Directory of Open Access Journals (Sweden)

    Josephine Chang Hui Lai

    2015-01-01

    Full Text Available Polylactic acid/fumed silica/clay (PLA/FS/clay (1.28E nanocomposites have been successfully prepared by solution-intercalation film-casting technique. The resultant nanocomposites were characterized by Fourier Transform Infrared Spectroscopy (FT-IR, Scanning Electron Microscopy (SEM, tensile test, thermogravimetric analysis (TGA, and moisture absorption test. The FT-IR spectrum indicated that PLA/FS/clay with 2 wt% had much broader peak compared to 5 wt%, 10 wt%, and 15 wt% nanocomposites. Incorporation of clay (1.28E with 2 wt% showed the best compatibility with PLA/FS matrix. PLA/FS/clay (1.28E nanocomposite with 2 wt% of clay loading had higher tensile strength and modulus compared to other nanocomposites. The thermal stability and activation energy of 2 wt% of PLA/FS/clay (1.28E nanocomposite are the highest among all the nanocomposites. The moisture absorbed into PLA/FS/clay (1.28E nanocomposite was significantly reduced with clay loading of 2 wt%.

  16. Reduction Rates for Higher Americium Oxidation States in Nitric Acid

    Energy Technology Data Exchange (ETDEWEB)

    Grimes, Travis Shane [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mincher, Bruce Jay [Idaho National Lab. (INL), Idaho Falls, ID (United States); Schmitt, Nicholas C [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-09-30

    The stability of hexavalent americium was measured using multiple americium concentrations and nitric acid concentrations after contact with the strong oxidant sodium bismuthate. Contrary to our hypotheses Am(VI) was not reduced faster at higher americium concentrations, and the reduction was only zero-order at short time scales. Attempts to model the reduction kinetics using zero order kinetic models showed Am(VI) reduction in nitric acid is more complex than the autoreduction processes reported by others in perchloric acid. The classical zero-order reduction of Am(VI) was found here only for short times on the order of a few hours. We did show that the rate of Am(V) production was less than the rate of Am(VI) reduction, indicating that some Am(VI) undergoes two electron-reduction to Am(IV). We also monitored the Am(VI) reduction in contact with the organic diluent dodecane. A direct comparison of these results with those in the absence of the organic diluent showed the reduction rates for Am(VI) were not statistically different for both systems. Additional americium oxidations conducted in the presence of Ce(IV)/Ce(III) ions showed that Am(VI) is reduced without the typical growth of Am(V) observed in the systems sans Ce ion. This was an interesting result which suggests a potential new reduction/oxidation pathway for Am in the presence of Ce; however, these results were very preliminary, and will require additional experiments to understand the mechanism by which this occurs. Overall, these studies have shown that hexavalent americium is fundamentally stable enough in nitric acid to run a separations process. However, the complicated nature of the reduction pathways based on the system components is far from being rigorously understood.

  17. Nitric acid: modeling osmotic coefficients and acid-base dissociation using the BIMSA theory.

    Science.gov (United States)

    Ruas, Alexandre; Pochon, Patrick; Simonin, Jean-Pierre; Moisy, Philippe

    2010-11-14

    This work is aimed at a description of the thermodynamic properties of highly concentrated aqueous solutions of nitric acid salts at 25 °C within the binding mean spherical approximation (BIMSA) theory. The predictive capability of this model was examined. First, Raman spectroscopy was used to study the proportion of associated nitric acid as a function of concentration. The corresponding apparent association constant values were compared with literature values. Besides, the BIMSA model, taking into account complex formation, was used to represent literature experimental osmotic coefficient variation with concentration. This theoretical description led to an assessment of the degree of association. The so calculated amount of associated nitric acid coincides accurately with our Raman experimental results up to a high concentration of acid.

  18. Nitric acid: modeling osmotic coefficients and acid-base dissociation using the BIMSA theory

    Energy Technology Data Exchange (ETDEWEB)

    Ruas, A.; Pochon, P.; Moisy, Ph. [CEA Marcoule, Nucl Energy Div, RadioChem and Proc Dept, F-30207 Bagnols Sur Ceze (France); Simonin, J. P. [Univ Paris 06, CNRS, UMR 7195, Lab PECSA, F-75252 Paris 05, (France)

    2010-07-01

    This work is aimed at a description of the thermodynamic properties of highly concentrated aqueous solutions of nitric acid salts at 25 C within the binding mean spherical approximation (BIMSA) theory. The predictive capability of this model was examined. First, Raman spectroscopy was used to study the proportion of associated nitric acid as a function of concentration. The corresponding apparent association constant values were compared with literature values. Besides, the BIMSA model, taking into account complex formation, was used to represent literature experimental osmotic coefficient variation with concentration. This theoretical description led to an assessment of the degree of association. The so calculated amount of associated nitric acid coincides accurately with our Raman experimental results up to a high concentration of acid. (authors)

  19. Energy integration of nitric acid production using pinch methodology

    Directory of Open Access Journals (Sweden)

    Ivaniš Gorica R.

    2015-01-01

    Full Text Available Pinch methodology was applied to the heat exchangers network (HEN synthesis of nitric acid production. The integration is analyzed in two ways, and the results are presented as two different solutions: (i the first solution is based on the original heat transfer equipment arrangement, (ii in order to eliminate the shortages of the first solution the second HEN was obtained using process simulation with optimized process parameters. Optimized HEN, with new arrangement of heat exchangers, gave good results in energy and process optimization. [Projekat Ministarstva nauke Republike Srbije, br. P172063

  20. Separation of thorium and uranium in nitric acid solution using silica based anion exchange resin.

    Science.gov (United States)

    Chen, Yanliang; Wei, Yuezhou; He, Linfeng; Tang, Fangdong

    2016-09-30

    To separate thorium and uranium in nitric acid solution using anion exchange process, a strong base silica-based anion exchange resin (SiPyR-N4) was synthesized. Batch experiments were conducted and the separation factor of thorium and uranium in 9M nitric acid was about 10. Ion exchange chromatography was applied to separate thorium and uranium in different ratios. Uranium could be eluted by 9M nitric acid and thorium was eluted by 0.1M nitric acid. It was proved that thorium and uranium can be separated and recovered successfully by this method.

  1. Hydrothermal nitric acid treatment for effectual lipid extraction from wet microalgae biomass.

    Science.gov (United States)

    Lee, Ilgyu; Park, Ji-Yeon; Choi, Sun-A; Oh, You-Kwan; Han, Jong-In

    2014-11-01

    Hydrothermal acid (combined with autoclaving and nitric acid) pretreatment was applied to Nannochloropsis salina as a cost-effective yet efficient way of lipid extraction from wet biomass. The optimal conditions for this pretreatment were determined using a statistical approach, and the roles of nitric acid were also determined. The maximum lipid yield (predicted: 24.6%; experimental: 24.4%) was obtained using 0.57% nitric acid at 120°C for 30min through response surface methodology. A relatively lower lipid yield (18.4%) was obtained using 2% nitric acid; however, chlorophyll and unsaturated fatty acids, both of which adversely affect the refinery and oxidative stability of biodiesel, were found to be not co-extracted. Considering its comparable extractability even from wet biomass and ability to reduce chlorophyll and unsaturated fatty acids, the hydrothermal nitric acid pretreatment can serve as one direct and promising route of extracting microalgae oil. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Removal of an acid fume system contaminated with perchlorates located within hot cell

    Energy Technology Data Exchange (ETDEWEB)

    Rosenberg, K.E.; Henslee, S.P.; Vroman, W.R.; Krsul, J.R.; Michelbacher, J.A.; Knighton, G.C.

    1992-09-01

    An add scrubbing system located within the confines of a highly radioactive hot cell at Argonne National Laboratory-West (ANL-W) was remotely removed. The acid scrubbing system was routinely used for the dissolution of irradiated reactor fuel samples and structural materials. Perchloric acid was one of the acids used in the dissolution process and remained in the system with its inherent risks. Personnel could not enter the hot cell to perform the dismantling of the acid scabbing system due to the high radiation field and the explosion potential associated with the perchlorates. A robot was designed and built at ANL-W and used to dismantle the system without the need for personnel entry into the hot cell. The robot was also used for size reduction of removed components and loading of the removed components into waste containers.

  3. Nitrosation and Nitration of Fulvic Acid, Peat and Coal with Nitric Acid.

    Directory of Open Access Journals (Sweden)

    Kevin A Thorn

    Full Text Available Nitrohumic acids, produced from base extraction of coals and peats oxidized with nitric acid, have received considerable attention as soil ammendments in agriculture. The nitration chemistry however is incompletely understood. Moreover, there is a need to understand the reaction of nitric acid with natural organic matter (NOM in general, in the context of a variety of environmental and biogeochemical processes. Suwannee River NOM, Suwannee River fulvic acid, and Pahokee Peat fulvic acid were treated with 15N-labeled nitric acid at concentrations ranging from 15% to 22% and analyzed by liquid and solid state 15N NMR spectroscopy. Bulk Pahokee peat and Illinois #6 coal were also treated with nitric acid, at 29% and 40% respectively, and analyzed by solid state 15N NMR spectroscopy. In addition to nitro groups from nitration of aromatic carbon, the 15N NMR spectra of all five samples exhibited peaks attributable to nitrosation reactions. These include nitrosophenol peaks in the peat fulvic acid and Suwannee River samples, from nitrosation of phenolic rings, and N-nitroso groups in the peat samples, from nitrosation of secondary amides or amines, the latter consistent with the peat samples having the highest naturally abundant nitrogen contents. Peaks attributable to Beckmann and secondary reactions of the initially formed oximes were present in all spectra, including primary amide, secondary amide, lactam, and nitrile nitrogens. The degree of secondary reaction product formation resulting from nitrosation reactions appeared to correlate inversely with the 13C aromaticities of the samples. The nitrosation reactions are most plausibly effected by nitrous acid formed from the reduction of nitric acid by oxidizable substrates in the NOM and coal samples.

  4. Nitrosation and nitration of fulvic acid, peat and coal with nitric acid

    Science.gov (United States)

    Thorn, Kevin A.; Cox, Larry G.

    2016-01-01

    Nitrohumic acids, produced from base extraction of coals and peats oxidized with nitric acid, have received considerable attention as soil ammendments in agriculture. The nitration chemistry however is incompletely understood. Moreover, there is a need to understand the reaction of nitric acid with natural organic matter (NOM) in general, in the context of a variety of environmental and biogeochemical processes. Suwannee River NOM, Suwannee River fulvic acid, and Pahokee Peat fulvic acid were treated with 15N-labeled nitric acid at concentrations ranging from 15% to 22% and analyzed by liquid and solid state 15N NMR spectroscopy. Bulk Pahokee peat and Illinois #6 coal were also treated with nitric acid, at 29% and 40% respectively, and analyzed by solid state 15N NMR spectroscopy. In addition to nitro groups from nitration of aromatic carbon, the 15N NMR spectra of all five samples exhibited peaks attributable to nitrosation reactions. These include nitrosophenol peaks in the peat fulvic acid and Suwannee River samples, from nitrosation of phenolic rings, and N-nitroso groups in the peat samples, from nitrosation of secondary amides or amines, the latter consistent with the peat samples having the highest naturally abundant nitrogen contents. Peaks attributable to Beckmann and secondary reactions of the initially formed oximes were present in all spectra, including primary amide, secondary amide, lactam, and nitrile nitrogens. The degree of secondary reaction product formation resulting from nitrosation reactions appeared to correlate inversely with the 13C aromaticities of the samples. The nitrosation reactions are most plausibly effected by nitrous acid formed from the reduction of nitric acid by oxidizable substrates in the NOM and coal samples.

  5. Nitrosation and Nitration of Fulvic Acid, Peat and Coal with Nitric Acid.

    Science.gov (United States)

    Thorn, Kevin A; Cox, Larry G

    2016-01-01

    Nitrohumic acids, produced from base extraction of coals and peats oxidized with nitric acid, have received considerable attention as soil ammendments in agriculture. The nitration chemistry however is incompletely understood. Moreover, there is a need to understand the reaction of nitric acid with natural organic matter (NOM) in general, in the context of a variety of environmental and biogeochemical processes. Suwannee River NOM, Suwannee River fulvic acid, and Pahokee Peat fulvic acid were treated with 15N-labeled nitric acid at concentrations ranging from 15% to 22% and analyzed by liquid and solid state 15N NMR spectroscopy. Bulk Pahokee peat and Illinois #6 coal were also treated with nitric acid, at 29% and 40% respectively, and analyzed by solid state 15N NMR spectroscopy. In addition to nitro groups from nitration of aromatic carbon, the 15N NMR spectra of all five samples exhibited peaks attributable to nitrosation reactions. These include nitrosophenol peaks in the peat fulvic acid and Suwannee River samples, from nitrosation of phenolic rings, and N-nitroso groups in the peat samples, from nitrosation of secondary amides or amines, the latter consistent with the peat samples having the highest naturally abundant nitrogen contents. Peaks attributable to Beckmann and secondary reactions of the initially formed oximes were present in all spectra, including primary amide, secondary amide, lactam, and nitrile nitrogens. The degree of secondary reaction product formation resulting from nitrosation reactions appeared to correlate inversely with the 13C aromaticities of the samples. The nitrosation reactions are most plausibly effected by nitrous acid formed from the reduction of nitric acid by oxidizable substrates in the NOM and coal samples.

  6. Impact of scaling on the nitric-glycolic acid flowsheet

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, D. [Savannah River Site (SRS), Aiken, SC (United States)

    2016-02-01

    Savannah River Remediation (SRR) is considering using glycolic acid as a replacement for formic acid in Sludge Receipt and Adjustment Tank (SRAT) processing in the Defense Waste Processing Facility (DWPF). Catalytic decomposition of formic acid is responsible for the generation of hydrogen, a potentially flammable gas, during processing. To prevent the formation of a flammable mixture in the offgas, an air purge is used to dilute the hydrogen concentration below the 60% of the Composite Lower Flammability Limit (CLFL). The offgas is continuously monitored for hydrogen using Gas Chromatographs (GCs). Since formic acid is much more volatile and toxic than glycolic acid, a formic acid spill would lead to the release of much larger quantities to the environment. Switching from formic acid to glycolic acid is expected to eliminate the hydrogen flammability hazard leading to lower air purges, thus downgrading of Safety Significant GCs to Process Support GCs, and minimizing the consequence of a glycolic acid tank leak in DWPF. Overall this leads to a reduction in process operation costs and an increase in safety margin. Experiments were completed at three different scales to demonstrate that the nitric-glycolic acid flowsheet scales from the 4-L lab scale to the 22-L bench scale and 220-L engineering scale. Ten process demonstrations of the sludge-only flowsheet for SRAT and Slurry Mix Evaporator (SME) cycles were performed using Sludge Batch 8 (SB8)-Tank 40 simulant. No Actinide Removal Process (ARP) product or strip effluent was added during the runs. Six experiments were completed at the 4-L scale, two experiments were completed at the 22-L scale, and two experiments were completed at the 220-L scale. Experiments completed at the 4-L scale (100 and 110% acid stoichiometry) were repeated at the 22-L and 220-L scale for scale comparisons.

  7. Extraction equilibrium of indium(III) from nitric acid solutions by di(2-ethylhexyl)phosphoric acid dissolved in kerosene

    National Research Council Canada - National Science Library

    Tsai, Hung-Sheng; Tsai, Teh-Hua

    2012-01-01

    The extraction equilibrium of indium(III) from a nitric acid solution using di(2-ethylhexyl) phosphoric acid (D2EHPA) as an acidic extractant of organophosphorus compounds dissolved in kerosene was studied...

  8. 46 CFR 151.50-80 - Nitric acid (70% or less).

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Nitric acid (70% or less). 151.50-80 Section 151.50-80 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES CARRYING BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-80 Nitric acid (70% or...

  9. Research on the Stability of Dimethyl Hydroxylamine-methyl Hydrazinein Nitric Acid Medium

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By the means of the comparison of the extraction of PU(Ⅲ) and plutonium in nitric acid mediumcontaining dimethyl hydroxylamine-methyl hydrazine and the analysis of the percent content of PU(Ⅳ) inthe system, the stability of dimethyl hydroxylamine-methyl hydrazine in nitric acid medium is

  10. Synthesis of nanosilica from silica fume using an acid-base precipitation technique and PVA as a nonionic surfactant

    Directory of Open Access Journals (Sweden)

    Vajihe Jafari

    2014-12-01

    Full Text Available The purpose of the present study was to synthesize and characterize nanosilica from alkali-extraction of silica fume under controlled conditions using poly (vinyl alcohol (PVA as a dispersing agent. The dissolution efficiency of silica fume was affected by various factors such as concentration of the reagent, reaction time and temperature. A maximum dissolution efficiency of 91% was achieved at the sodium hydroxide solution concentration of 2.5 M, after areaction time of 30 minutes and at areaction temperature of 80°C. The microstructure and morphology of the obtained nanosilica powder at the optimum conditions were characterized using scanning electron microscopy (SEM. SEM images confirmed the formation of smaller and less agglomerated nanosilica particles due to the existence of the surfactant. Further, the synthesized nanosilica was characterized by Fourier transform infrared (FTIR spectroscopy, X-ray diffractometry (XRF and X-ray diffraction (XRD. The results show that the synthesized nanosilica consisted of pure silica particles.

  11. Effect of Nitric Acid Concentrations on Synthesis and Stability of Maghemite Nanoparticles Suspension

    Directory of Open Access Journals (Sweden)

    Irwan Nurdin

    2014-01-01

    Full Text Available Maghemite (γ-Fe2O3 nanoparticles have been synthesized using a chemical coprecipitation method at different nitric acid concentrations as an oxidizing agent. Characterization of all samples performed by several techniques including X-ray diffraction (XRD, transmission electron microscopy (TEM, alternating gradient magnetometry (AGM, thermogravimetric analysis (TGA, dynamic light scattering (DLS, and zeta potential. The XRD patterns confirmed that the particles were maghemite. The crystallite size of all samples decreases with the increasing concentration of nitric acid. TEM observation showed that the particles have spherical morphology with narrow particle size distribution. The particles showed superparamagnetic behavior with decreased magnetization values at the increasing concentration of nitric acid. TGA measurement showed that the stability temperature decreases with the increasing concentration of nitric acid. DLS measurement showed that the hydrodynamic particle sizes decrease with the increasing concentration of nitric acid. Zeta potential values show a decrease with the increasing concentration of nitric acid. The increasing concentration of nitric acid in synthesis of maghemite nanoparticles produced smaller size particles, lower magnetization, better thermal stability, and more stable maghemite nanoparticles suspension.

  12. Effect of nitric acid concentrations on synthesis and stability of maghemite nanoparticles suspension.

    Science.gov (United States)

    Nurdin, Irwan; Johan, Mohd Rafie; Yaacob, Iskandar Idris; Ang, Bee Chin

    2014-01-01

    Maghemite (γ-Fe2O3) nanoparticles have been synthesized using a chemical coprecipitation method at different nitric acid concentrations as an oxidizing agent. Characterization of all samples performed by several techniques including X-ray diffraction (XRD), transmission electron microscopy (TEM), alternating gradient magnetometry (AGM), thermogravimetric analysis (TGA), dynamic light scattering (DLS), and zeta potential. The XRD patterns confirmed that the particles were maghemite. The crystallite size of all samples decreases with the increasing concentration of nitric acid. TEM observation showed that the particles have spherical morphology with narrow particle size distribution. The particles showed superparamagnetic behavior with decreased magnetization values at the increasing concentration of nitric acid. TGA measurement showed that the stability temperature decreases with the increasing concentration of nitric acid. DLS measurement showed that the hydrodynamic particle sizes decrease with the increasing concentration of nitric acid. Zeta potential values show a decrease with the increasing concentration of nitric acid. The increasing concentration of nitric acid in synthesis of maghemite nanoparticles produced smaller size particles, lower magnetization, better thermal stability, and more stable maghemite nanoparticles suspension.

  13. Omega-3 fatty acids improve psychomotor performance via mechanism not related to nitric acid production

    Directory of Open Access Journals (Sweden)

    Marwan S. M. Al-Nimer

    2012-01-01

    Full Text Available Omega-3 fatty acids (ω-3FAs are essential polyunsaturated fats that protect the brain from cognitive impairment. It increases the activity of endothelial nitric oxide synthetase (eNOS and thereby increases the nitric acid (NO production. This study aimed to explore the effect of ω-3FAs on psychomotor performance and to relate this effect to the reactive nitrogen species. This study was conducted in Department of Pharmacology, College of Medicine, Al-Mustansiriya University in Baghdad, Iraq. Twenty healthy subjects, allocated randomly from medical college students, were participated in the single blind clinical trial. Participants were divided into two groups, each of ten subjects to receive either placebo or (ω-3FAs (750 mg single oral dose daily for 5 days. They were asked to perform psychomotor performance before and after 5 days of treatment, and venous blood was obtained for determination of serum nitric oxide (NO and peroxynitrite (ONOO. ω-3FAs treated group was significantly different from placebo-treated group in reducing choice and motor reaction times as well as the critical flicker frequency threshold. The serum levels of NO and ONOO in ω-3FAs-treated group did not significantly differ from placebo-treated group. Short term supplementation of ω-3FAs improves the psychomotor performance in young healthy subjects via a mechanism not related to the production of nitric oxide production. Inflorescence is a panicle few flowered and fruit is a capsule. The data of the results obtained were presented and discussed.

  14. Thermal Hazard Evaluation of Lauroyl Peroxide Mixed with Nitric Acid

    Directory of Open Access Journals (Sweden)

    Chi-Min Shu

    2012-07-01

    Full Text Available Many thermal runaway incidents have been caused by organic peroxides due to the peroxy group, –O–O–, which is essentially unstable and active. Lauroyl peroxide (LPO is also sensitive to thermal sources and is incompatible with many materials, such as acids, bases, metals, and ions. From the thermal decomposition reaction of various concentrations of nitric acid (HNO3 (from lower to higher concentrations with LPO, experimental data were obtained as to its exothermic onset temperature (T0, heat of decomposition (ΔHd, isothermal time to maximum rate (TMRiso, and other safety parameters exclusively for loss prevention of runaway reactions and thermal explosions. As a novel finding, LPO mixed with HNO3 can produce the detonation product of 1-nitrododecane. We used differential scanning calorimetry (DSC, thermal activity monitor III (TAM III, and gas chromatography/mass spectrometer (GC/MS analyses of the reactivity for LPO and itself mixed with HNO3 to corroborate the decomposition reactions and reaction mechanisms in these investigations.

  15. Assessment of electrochemical potentiokinetic reactivation tests to qualify stainless steel for nitric acid service

    Energy Technology Data Exchange (ETDEWEB)

    Olsen, A.R.; Dillon, J.J.; Peters, A.H.; Clift, T.L.

    1986-12-31

    To minimize the costs and delivery time delays associated with purchasing type 304L stainless steel materials for service in nitric-acid-containing media, an alternative to the current Oak Ridge Y-12 Plant requirement of testing in accordance with American Society for Testing and Materials (ASTM) A 262, Practice C (the boiling nitric acid test), is being sought. A possible candidate is the electrochemical potentiokinetic reactivation (EPR) test being developed for the nuclear industry and under consideration for acceptance as an ASTM standard. Based on a review of the literature and some limited screening tests, this test, as currently proposed, is not a suitable substitute for the nitric acid test. However, with additional development the EPR test is a likely candidate for providing a quantitative substitute for the current qualitative oxalic acid etching (ASTM A 282, Practice A) often used to accept, but not reject, materials for use in a nitric acid medium.

  16. Transuranic contamination of stainless steel in nitric acid

    Science.gov (United States)

    Kerry, Timothy; Banford, Anthony W.; Thompson, Olivia R.; Carey, Thomas; Schild, Dieter; Geist, Andreas; Sharrad, Clint A.

    2017-09-01

    Stainless steels coupons have been exposed to transuranic species in conditions representative of those found in a spent nuclear fuel reprocessing plant. Stainless steel was prepared to different surface finishes and exposed to nitric acid of varying concentrations containing 237Np, 239Pu or 243Am for one month at 50 °C. Contamination by these transuranics has been observed on all surfaces exposed to the solution through the use of autoradiography. This technique showed that samples held in 4 M HNO3 bind 2-3 times as much radionuclide as those held in 10.5 M HNO3. It was also found that the polished steel surfaces generally took up more transuranic contamination than the etched and ;as received; steel finishes. The extent of corrosion on the steel surfaces was found, by scanning electron microscopy, to be greater in solutions containing Np and Pu in comparison to that observed from contact with Am containing solutions, indicating that redox activity of transuranics can influence the mechanism of stainless steel corrosion.

  17. Nitric acid trihydrate (NAT formation at low NAT supersaturations

    Directory of Open Access Journals (Sweden)

    C. Voigt

    2004-12-01

    Full Text Available A polar stratospheric cloud (PSC was observed on 6 February 2003 in the Arctic stratosphere by in-situ measurements onboard the high-altitude research aircraft Geophysica. Low number densities (~10−4 cm−3 of nitric acid (HNO3 containing particles – probably NAT – with diameters up to 6 µm were measured at altitudes between 18 and 20 km. These particles have the potential to grow further and to remove HNO3 from the stratosphere, thereby enhancing polar ozone loss. Interestingly, the NAT particles formed in less than a day at temperatures T>TNAT−3.5 K, just slightly below the NAT equilibrium temperature TNAT. This unique measurement of PSC formation at extremely low NAT saturation ratios (SNAT≤11 constrains current NAT nucleation theories. In particular, NAT formation on ice can for certain be excluded. Conversely, we suggest that meteoritic particles may be favorable candidates for triggering nucleation of NAT at the observed low number densities.

  18. Moessbauer Spectroscopic Studies of {sup 237}Np in frozen nitric acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Nakada, M; Wang, J; Kitazawa, T; Takahashi, M; Takeda, M; Masaki, N M; Yamashita, T [Department of Materials Science, Japan Atomic Energy Research Institute (JAERI, present JAEA: Japan Atomic Energy Agency), Tokai, Naka, Ibaraki 319-1195 (Japan); Tsutsui, S, E-mail: wangjh@dicp.ac.c [Advanced Science Research Center, JAERI, Tokai, Naka, Ibaraki 319-1195 (Japan)

    2010-03-01

    We applied Moessbauer spectroscopy to {sup 237}Np in nitric acid solutions to study chemical states. Sample solutions were adjusted to 50 mg/ml of Np(V) and Np(VI) concentration in 0.6 M nitric acid solutions. These solutions were put into original designed containers for samples and mounted to sample holders. The values of isomer shift (IS, relative to NpAl{sub 2}) of Np(V) and Np(VI) in 0.6 M nitric acid were -17.4(1) and -37.2(3) mm/s at about 10 K, respectively. It was found that Np(V) had 7 coordination number and Np(VI) had 8 in nitric acid solutions from values of IS.

  19. Research on the Stability of Diethyl Hydroxylamine in Nitric Acid Medium

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By the means of the comparison of the extraction of PU(Ⅲ,Ⅳ) and plutonium in the aqueous Phasecontaining salting-free agent, the stability of diethyl hydroxylamine in nitric acid medium is investigated.

  20. HIRDLS/Aura Level 3 Nitric Acid (HNO3) Zonal Fourier Coefficients V007

    Data.gov (United States)

    National Aeronautics and Space Administration — The "HIRDLS/Aura Level 3 Nitric Acid (HNO3) Zonal Fourier Coefficients" version 7 data product (H3ZFCHNO3) contains the entire mission (~3 years) of HIRDLS data...

  1. Enhancement of aged and denatured fingerprints using the cyanoacrylate fuming technique following dusting with amino acid-containing powders.

    Science.gov (United States)

    Nixon, Carly; Almond, Matthew J; Baum, John V; Bond, John W

    2013-03-01

    We have carried out experiments to investigate the aging of latent fingerprints deposited on black PVC over a period of 4-15 weeks. A thumbprint was used in each case and before deposition of the print the donor rubbed their thumb around their nose to add sebaceous deposits. We have studied the effect of heat, light, and moisture and we find that moisture is the most significant factor in the degradation of the latent print. We have attempted to enhance these latent prints by dusting with valine powder or powders composed of valine mixed with gold or red fluorescent commercial fingerprint powders. To make a direct comparison between "treated" and "untreated" prints, the prints were cut in half with one-half being "treated" and one-half not. Our studies show the best results being obtained when powders of valine and red fluorescent powders are applied prior to cyanoacrylate fuming.

  2. Disposition and transportation of surplus radioactive low specific activity nitric acid. Volume 1, Environmental Assessment

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-05-01

    DOE is deactivating the PUREX plant at Hanford; this will involve the disposition of about 692,000 liters (183,000 gallons) of surplus nitric acid contaminated with low levels of U and other radionuclides. The nitric acid, designated as low specific activity, is stored in 4 storage tanks at PUREX. Five principal alternatives were evaluated: transfer for reuse (sale to BNF plc), no action, continued storage in Hanford upgraded or new facility, consolidation of DOE surplus acid, and processing the LSA nitric acid as waste. The transfer to BNF plc is the preferred alternative. From the analysis, it is concluded that the proposed disposition and transportation of the acid does not constitute a major federal action significantly affecting the quality of the human environment within the meaning of NEPA; therefore an environmental impact statement is not required.

  3. Proton transfer reactions between nitric acid and acetone, hydroxyacetone, acetaldehyde and benzaldehyde in the solid phase.

    Science.gov (United States)

    Lasne, Jérôme; Laffon, Carine; Parent, Philippe

    2012-12-01

    The heterogeneous and homogeneous reactions of acetone, hydroxyacetone, acetaldehyde and benzaldehyde with solid nitric acid (HNO(3)) films have been studied with Reflection-Absorption Infrared Spectroscopy (RAIRS) under Ultra-High Vacuum (UHV) conditions in the 90-170 K temperature range. In the bulk or at the surface of the films, nitric acid transfers its proton to the carbonyl function of the organic molecules, producing protonated acetone-H(+), hydroxyacetone-H(+), acetaldehyde-H(+) and benzaldehyde-H(+), and nitrate anions NO(3)(-), a reaction not observed when nitric acid is previously hydrated [J. Lasne, C. Laffon and Ph. Parent, Phys. Chem. Chem. Phys., 2012, 14, 697]. This provides a molecular-scale description of the carbonyl protonation reaction in an acid medium, the first step of the acid-catalyzed condensation of carbonyl compounds, fuelling the growth of secondary organic aerosols (SOA) in the atmosphere.

  4. Laboratory studies of 2H evaporator scale dissolution in dilute nitric acid

    Energy Technology Data Exchange (ETDEWEB)

    Oji, L.

    2014-09-23

    The rate of 2H evaporator scale solids dissolution in dilute nitric acid has been experimentally evaluated under laboratory conditions in the SRNL shielded cells. The 2H scale sample used for the dissolution study came from the bottom of the evaporator cone section and the wall section of the evaporator cone. The accumulation rate of aluminum and silicon, assumed to be the two principal elemental constituents of the 2H evaporator scale aluminosilicate mineral, were monitored in solution. Aluminum and silicon concentration changes, with heating time at a constant oven temperature of 90 deg C, were used to ascertain the extent of dissolution of the 2H evaporator scale mineral. The 2H evaporator scale solids, assumed to be composed of mostly aluminosilicate mineral, readily dissolves in 1.5 and 1.25 M dilute nitric acid solutions yielding principal elemental components of aluminum and silicon in solution. The 2H scale dissolution rate constant, based on aluminum accumulation in 1.5 and 1.25 M dilute nitric acid solution are, respectively, 9.21E-04 ± 6.39E-04 min{sup -1} and 1.07E-03 ± 7.51E-05 min{sup -1}. Silicon accumulation rate in solution does track the aluminum accumulation profile during the first few minutes of scale dissolution. It however diverges towards the end of the scale dissolution. This divergence therefore means the aluminum-to-silicon ratio in the first phase of the scale dissolution (non-steady state conditions) is different from the ratio towards the end of the scale dissolution. Possible causes of this change in silicon accumulation in solution as the scale dissolution progresses may include silicon precipitation from solution or the 2H evaporator scale is a heterogeneous mixture of aluminosilicate minerals with several impurities. The average half-life for the decomposition of the 2H evaporator scale mineral in 1.5 M nitric acid is 12.5 hours, while the half-life for the decomposition of the 2H evaporator scale in 1.25 M nitric acid is 10

  5. Extraction equilibrium of indium(III) from nitric acid solutions by di(2-ethylhexyl)phosphoric acid dissolved in kerosene.

    Science.gov (United States)

    Tsai, Hung-Sheng; Tsai, Teh-Hua

    2012-01-04

    The extraction equilibrium of indium(III) from a nitric acid solution using di(2-ethylhexyl) phosphoric acid (D2EHPA) as an acidic extractant of organophosphorus compounds dissolved in kerosene was studied. By graphical and numerical analysis, the compositions of indium-D2EHPA complexes in organic phase and stoichiometry of the extraction reaction were examined. Nitric acid solutions with various indium concentrations at 25 °C were used to obtain the equilibrium constant of InR₃ in the organic phase. The experimental results showed that the extraction distribution ratios of indium(III) between the organic phase and the aqueous solution increased when either the pH value of the aqueous solution and/or the concentration of the organic phase extractant increased. Finally, the recovery efficiency of indium(III) in nitric acid was measured.

  6. Effects of Nitric Acid Concentration on the Stability of Alumina Sols

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Alumina sols with a mlar ratio of 1: 50 between aluminum sec- butoxide ( ASB ) and H2 O werefabricated by adding various amounts of nitric acid.The particle shape, zeta potential, polydispersity and effective particle size of alumina sol were examined by a TEM, a zeta PALS granularity analyzer and a zetaPALS zeta potential analyzer, respectively.By analyzing the change of zeta potential and double- layer thickness with nitric acid concentration, the potential energy curves of colloidal particles were mapped on the basis of DLVO theory, and the effects of nitric acid concentration on the stability of alumina sols were intensively studied.The results show that for the alumina sols with a mol ratio of 1: 50 between ASB and H2 O, the total interaction energy of the colloidal particle is at a maximum when the nitric acid concentration is 0.22 mol/ L.Therefore, the stability of the colloid reaches optimum at the nitric acid concentration of 0.22 mol/L.

  7. Serum uric acid levels and leukocyte nitric oxide production in multiple sclerosis patients outside relapses

    NARCIS (Netherlands)

    Mostert, JP; Ramsaransing, GSM; Heerserna, DJ; Heerings, M; Wilczak, N; De Keyser, J

    2005-01-01

    Background: A number of studies found that patients with multiple sclerosis (MS) have low serum levels of uric acid. It is unclear whether this represents a primary deficit or secondary effect. Uric acid is a scavenger of peroxynitrite, which is the product of nitric oxide (NO) and superoxide. Becau

  8. Batch salicylic acid nitration by nitric acid/acetic acid mixture under isothermal, isoperibolic and adiabatic conditions.

    Science.gov (United States)

    Andreozzi, R; Canterino, M; Caprio, V; Di Somma, I; Sanchirico, R

    2006-12-01

    Runaway phenomena and thermal explosions can originate during the nitration of salicylic acid by means of a nitric acid/acetic acid mixture when the thermal control is lost, mainly as a result of the formation and thermal decomposition of picric acid. The prediction of the behaviour of this system is thus of great importance in view of possible industrial applications and the need to avoid the occurrence of unwanted dangerous events. During a previous investigation a model was developed to simulate its behaviour when the starting concentration of the substrate is too low, thus, preventing the precipitation of poor soluble intermediates. In this work this model is extended to deal with more concentrated systems even in case of a solid phase separating during the process. To this purpose the previously assessed dependence of the solubility of 3-nitro and 5-nitrosalicylic acids upon temperature and nitric acid concentration is included in the model. It is assumed that when 3-nitro and 5-nitrosalicylic acids are partially suspended in the reacting medium a kinetic regime of "dissolution with reaction" is established; that is, the redissolution of these species is a fast process compared to the successive nitration to give dinitroderivatives. Good results are obtained in the comparison of the experimental data with those calculated both in isoperibolic and adiabatic conditions when the revised model is used.

  9. Integrating nitric oxide into salicylic acid and jasmonic acid/ethylene plant defense pathways

    DEFF Research Database (Denmark)

    Mur, Luis A J; Prats, Elena; Pierre, Sandra

    2013-01-01

    Plant defence against pests and pathogens is known to be conferred by either salicylic acid (SA) or jasmonic acid (JA)/ethylene (ET) pathways, depending on infection or herbivore-grazing strategy. It is well attested that SA and JA/ET pathways are mutually antagonistic allowing defence responses...... to be tailored to particular biotic stresses. Nitric oxide (NO) has emerged as a major signal influencing resistance mediated by both signalling pathways but no attempt has been made to integrate NO into established SA/JA/ET interactions. NO has been shown to act as an inducer or suppressor of signalling along...... the cytoplasm to reduce TGA activation. In JA biosynthesis, NO will initiate the expression of JA biosynthetic enzymes, presumably to over-come any antagonistic effects of SA on JA-mediated transcription. NO will also initiate the expression of ET biosynthetic genes but a suppressive role is also observed...

  10. Preparation of nitric humic acid by catalytic oxidation from Guizhou coal with catalysts

    Institute of Scientific and Technical Information of China (English)

    Yang Zhiyuan; Gong Liang; Ran Pan

    2012-01-01

    Nitric humic acid was prepared by catalytic oxidation between nitric acid and Guizhou coal,with added catalysts.We investigated catalytic oxidation processes and the factors that affect the reactions.The effects of different catalysts,including NiSO4 support on active carbon (AC-NiSO4),NiSO4 support on silicon dioxide (SiO2-NiSO4),composites of SO42-/Fe2O3,Zr-iron and vanadium-iron composite were studied.As well.we investigated nitric humic acid yields and the chemical structure of products by element analysis,FT-IR and E4/E6 (an absorbance ratio at wavelengths of 465 and 665 nm of humic acid alkaline extraction solutions).The results show that the catalytic oxidation reaction with added catalysts can increase humic acid yields by 18.7%,16.36%,12.94%,5.61% and 8.59%,respectively.The highest yield of humic acid,i.e.,36.0%,was obtained with AC-NiSO4 as the catalyst.The amounts of C and H decreased with the amount of nitrogen.The increase in the E4/E6 ratio in catalytic oxidation of (Guizhou) coal shows that small molecular weights and high yields of nitric humic acid can be obtained by catalytic oxidation reactions.

  11. Observation of gaseous nitric acid production at a high-energy proton accelerator facility

    CERN Document Server

    Kanda, Y; Nakajima, H

    2005-01-01

    High-energy protons and neutrons produce a variety of radionuclides as well as noxious and oxidative gases, such as ozone and nitric acid, in the air mainly through the nuclear spallation of atmospheric elements. Samples were collected from the surfaces of magnets, walls, and floors in the neutrino beamline tunnel and the target station of the KEK 12-GeV proton synchrotron facility by wiping surfaces with filter paper. Considerably good correlations were found between the amounts of nitrate and tritium and between those of nitrate and /sup 7/Be. This finding gives evidence that at high-energy proton facilities, nitric acid is produced in the radiolysis of air in beam- loss regions. Also, the nitric acid on the surfaces was found to be desorbed and tended to be more uniform throughout the tunnel due to air circulation. The magnitude of diminishing from the surfaces was in the order of tritium>nitrate>/sup 7/Be1).

  12. TESTING OF 304L STAINLESS STEEL IN NITRIC ACID ENVIRONMENTS WITH FLUORIDES AND CHLORIDES

    Energy Technology Data Exchange (ETDEWEB)

    Mickalonis, J.

    2010-10-04

    Impure radioactive material processed in nitric acid solutions resulted in the presence of chlorides in a dissolver fabricated from 304L stainless steel. An experimental program was conducted to study the effects of chloride in nitric acid/fluoride solutions on the corrosion of 304L stainless steel. The test variables included temperature (80, 95, and 110 C) and the concentrations of nitric acid (6, 12, and 14 M), fluoride (0.01, 0.1, and 0.2 M) and chloride (100, 350, 1000, and 2000 ppm). The impact of welding was also investigated. Results showed that the chloride concentration alone was not a dominant variable affecting the corrosion, but rather the interaction of chloride with fluoride significantly affected corrosion.

  13. Effect of nitric acid treatment on activated carbon derived from oil palm shell

    Science.gov (United States)

    Allwar, Allwar; Hartati, Retno; Fatimah, Is

    2017-03-01

    The primary object of this work is to study the effect of nitric acid on the porous and morphology structure of activated carbon. Production of activated carbon from oil palm shell was prepared with pyrolysis process at temperature 900°C and by introduction of 10 M nitric acid. Determination of surface area, pore volume and pore size distribution of activated carbon was conducted by the N2 adsorption-desorption isotherm at 77 K. Morphology structure and elemental micro-analysis of activated carbon were estimated by Scanning Electron Microscopy (SEM) and energy dispersive X-ray (EDX), respectively. The result shows that activated carbon after treating with nitric acid proved an increasing porous characteristics involving surface area, pore volume and pore size distribution. It also could remove the contaminants including metals and exhibit an increasing of pores and crevices all over the surface.

  14. Stabilization and Solidification of Nitric Acid Effluent Waste at Y-12

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Dileep [Argonne National Lab. (ANL), Argonne, IL (United States); Lorenzo-Martin, Cinta [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-12-16

    Consolidated Nuclear Security, LLC (CNS) at the Y-12 plant is investigating approaches for the treatment (stabilization and solidification) of a nitric acid waste effluent that contains uranium. Because the pH of the waste stream is 1-2, it is a difficult waste stream to treat and stabilize by a standard cement-based process. Alternative waste forms are being considered. In this regard, Ceramicrete technology, developed at Argonne National Laboratory, is being explored as an option to solidify and stabilize the nitric acid effluent wastes.

  15. Coextraction of uranium(VI) form nitric acid solutions by N,N—diethyldecanamide and TBP

    Institute of Scientific and Technical Information of China (English)

    SunGuo-Xin; SunSi-Xiu; 等

    1997-01-01

    The partition of uranium(VI) between nitric acid and N,N-diethydecanamide,C9H19CON(C2H5)2,(DEDEA)in kerosene has been investigated at various concentrations of nitric acid,extractant and slating -out agent LiNO3.The mechanism of extraction is discussed in the light of the results obtained.The effect of TBP on the extraction of uranium(VI) with DEDEA has also been considered.There is apparent synergism between these two extractants at low concentration of TBP;however,at higher concentration,distributioin ratio decreases.

  16. OPTIMAL CONTROL OF AUTOCLAVE START MODE IN THE PRODUCTION OF NITRIC ACID

    OpenAIRE

    Ладієва, Леся Ростиславівна; Ширма, А. В.

    2015-01-01

    The algorithm of optimal control of autoclave start mode in the production of nitric acid is proposed. By optimality criterion is selected minimum time-autoclave at preset mode with the restriction on the concentration of nitric acid. End time start mode is entered on the terminal part of the cost function. The method of penalties and a gradient procedure is used to solve the problem. The applied algorithm is allowed to bring an autoclave at a given technological regime.Keywords: production o...

  17. OPTIMAL CONTROL OF AUTOCLAVE START MODE IN THE PRODUCTION OF NITRIC ACID

    OpenAIRE

    Ладієва, Леся Ростиславівна; Ширма, А. В.

    2015-01-01

    The algorithm of optimal control of autoclave start mode in the production of nitric acid is proposed. By optimality criterion is selected minimum time-autoclave at preset mode with the restriction on the concentration of nitric acid. End time start mode is entered on the terminal part of the cost function. The method of penalties and a gradient procedure is used to solve the problem. The applied algorithm is allowed to bring an autoclave at a given technological regime.Keywords: production o...

  18. Material compatibility evaluation for DWPF nitric-glycolic acid-literature review

    Energy Technology Data Exchange (ETDEWEB)

    Mickalonis, J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Skidmore, E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2013-06-01

    Glycolic acid is being evaluated as an alternative for formic and nitric acid in the DWPF flowsheet. Demonstration testing and modeling for this new flowsheet has shown that glycolic acid and glycolate has a potential to remain in certain streams generated during the production of the nuclear waste glass. A literature review was conducted to assess the impact of glycolic acid on the corrosion of the materials of construction for the DWPF facility as well as facilities downstream which may have residual glycolic acid and glycolates present. The literature data was limited to solutions containing principally glycolic acid.

  19. Gamma radiolytic stability of CyMe4BTBP and the effect of nitric acid

    Directory of Open Access Journals (Sweden)

    Schmidt Holger

    2015-12-01

    Full Text Available The highly selective nitrogen donor ligand CyMe4BTBP for An(III separation by solvent extraction was irradiated in a 60Co γ-source under varying conditions. Organic solutions of 10 mmol/L ligand in 1-octanol were contacted with different concentrations of nitric acid to observe the influence of an aqueous phase during irradiation. In subsequent liquid-liquid extraction experiments, distribution ratios of 241Am and 152Eu were determined. Distribution ratios decreased with increasing absorbed dose when irradiation was performed in the absence of nitric acid. With addition of nitric acid, initial distribution ratios remained constant over the whole examined dose range up to 300 kGy. For qualitative determination of radiolysis products, HPLC-MS measurements were performed. The protective effect of nitric acid was confirmed, since in samples irradiated with acid contact, no degradation products were observed, but only addition products of the 1-octanol molecule to the CyMe4BTBP molecule.

  20. Updating Older Fume Hoods.

    Science.gov (United States)

    Saunders, G. Thomas

    1985-01-01

    Provides information on updating older fume hoods. Areas addressed include: (1) adjustment of the hood's back baffle; (2) hood air leakage; (3) light level; (4) hood location in relation to room traffic and room air; and (5) establishing and maintaining hood performance. (JN)

  1. CHARACTERIZATION OF H CANYON CONDUCTIVITY METER INDICATIONS WITH ELEVATED URANIUM IN NITRIC ACID

    Energy Technology Data Exchange (ETDEWEB)

    Nash, C

    2007-10-31

    Solution conductivity data from the 1CU conductivity meter in H-Canyon shows that uranium concentration in the 0 to 30 gram per liter (g/L) range has no statistically significant effect on the calibration of free nitric acid measurement. Based on these results, no additional actions are needed on the 1CU Conductivity Meter prior to or during the processing of uranium solutions in the 0 to 30 g/L range. A model based only on free nitric acid concentration is shown to be appropriate for explaining the data. Data uncertainties for the free acid measurement of uranium-bearing solutions are 8.5% or less at 95% confidence. The analytical uncertainty for calibrating solutions is an order of magnitude smaller only when uranium is not present, allowing use of a more accurate analytical procedure. Literature work shows that at a free nitric acid level of 0.33 M, uranium concentration of 30 g/L and 25 C, solution conductivity is 96.4% of that of a uranium-free solution. The level of uncertainties in the literature data and its fitting equation do not justify calibration changes based on this small depression in solution conductivity. This work supports preparation of H-Canyon processing of Super Kukla fuel; however, the results will be applicable to the processing of any similar concentration uranium and nitric acid solution. Super Kukla fuel processing will increase the uranium concentration above the nominal zero to 10 g/L level, though not above 30 g/L. This work examined free nitric acid levels ranging from 0.18 to 0.52 molar. Temperature ranged from 27.9 to 28.3 C during conductivity testing. The data indicates that sequential order of measurement is not a significant factor. The conductivity meter was thus flushed effectively between measurements as desired.

  2. Research on the Reaction Between Technetium and Hydrazine in Nitric Acid Medium

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The reaction between technetium and hydrazine in nitric acid medium was studied by the titration ofthe concentration of hydrazine and pursuing the concentration of heptavalent technetium along with time.It is approved that the reaction between technetium and hydrazine includes an inducing period, a fast

  3. 77 FR 53144 - Nitric Acid; Exemption From the Requirement of a Tolerance

    Science.gov (United States)

    2012-08-31

    ... followed by pulmonary edema. Acute ingestion of nitric acid may result in ulceration, hemorrhage and... carcinogenicity of nitrate in food or drinking water. There were no treatment related effects observed in the 2... no concern for fetal susceptibility. There were no treatment related effects observed in the 2...

  4. White Paper on Potential Hazards Associated with Contaminated Cheesecloth Exposed to Nitric Acid Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Hypes, Philip A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-09-20

    This white paper addresses the potential hazards associated with waste cheesecloth that has been exposed to nitric acid solutions. This issue was highlighted by the cleanup of a 100 ml leak of aqueous nitric acid solution containing Heat Source (HS) plutonium on 21 June 2016. Nitration of cellulosic material is a well-understood process due to industrial/military applications of the resulting material. Within the Department of Energy complex, nitric acids have been used extensively, as have cellulosic wipes. If cellulosic materials are nitrated, the cellulosic material can become ignitable and in extreme cases, reactive. We have chemistry knowledge and operating experience to support the conclusion that all current wastes are safe and compliant. There are technical questions worthy of further experimental evaluation. An extent of condition evaluation has been conducted back to 2004. During this time period there have been interruptions in the authorization to use cellulosic wipes in PF-4. Limited use has been authorized since 2007 (for purposes other than spill cleanup), so our extent of condition includes the entire current span of use. Our evaluation shows that there is no indication that process spills involving high molarity nitric acid were cleaned up with cheesecloth since 2007. The materials generated in the 21 June leak will be managed in a safe manner compliant with all applicable requirements.

  5. Synthesis and bioactivity of novel nitric oxide-releasing ursolic acid derivatives

    Institute of Scientific and Technical Information of China (English)

    Li Chen; Wen Qiu; Jia Tang; Zhi Feng Wang; Shu Ying He

    2011-01-01

    A series of furoxan-based novel nitric oxide-donating ursolic acid (UA) derivatives (7a-f) were synthesized, and their cytotoxic activities against HepG2 cells in vitro were evaluated by MTT method. It was found that 7a-d and 7f showed more potent cytotoxic activities than control 5-fluorouracil and UA.

  6. TWOPOT: a computer model of the two-pot extractive distillation concept for nitric acid

    Energy Technology Data Exchange (ETDEWEB)

    Jubin, R.T.; Holland, W.D.; Counce, R.M.; Beckwith, D.R.

    1985-05-01

    A mathematical model, TWOPOT, of the ''two-pot'' extractive distillation concept for nitric acid concentration has been developed. Prediction from a computer simulation using this model shows excellent agreement with the experimental data. This model is recommended for use in the design of large-scale, similar-purpose equipment. 9 refs., 15 figs., 2 tabs.

  7. ExoMol molecular line lists: XI The spectrum of nitric acid

    CERN Document Server

    Pavlyuchko, Anatoly I; Tennyson, Jonathan

    2015-01-01

    Nitric acid is a possible biomarker in the atmospheres of exoplanets. An accurate line list of rotational and rotational-vibrational transitions is computed for nitric acid (HNO$_3$). This line list covers wavelengths longer than 1.42 $\\mu$m (0 - 7000 cm$^{-1}$) and temperatures up to 500 K. The line list is computed using a hybrid variational -- perturbation theory and empirically tuned potential energy and dipole surfaces. It comprises almost 7 billion transitions involving rotations up to $J=100$. Comparisons with spectra from the HITRAN and PNNL databases demonstrate the accuracy of our calculations. Synthetic spectra of water - nitric acid mixturessuggest that nitric acid has features at 7.5 and 11.25 $\\mu$m that are capable of providing a clear signature for HNO$_3$; the feature at 11.25 $\\mu$m is particularly promising. Partition functions plus full line lists of transitions are made available in an electronic form as supplementary data to the article and at www.exomol.com.

  8. Dissolution of sludges containing uranium dioxide and metallic uranium in nitric acid

    Energy Technology Data Exchange (ETDEWEB)

    Flament, T.A.

    1998-08-25

    The dissolution in nitric acid of sludges containing uranium oxide and uranium has been modeled. That study has shown that it was necessary to continuously feed the dissolver to have an appropriate control of the reaction. If a unique procedure is deemed preferable, NH03 6M has been used.

  9. Continuous wet denuder measurements of atmospheric nitric and nitrous acids during the 1999 Atlanta Supersite

    NARCIS (Netherlands)

    Genfa, Z.; Slanina, J.; Boring, C.B.; Jongejan, A.C.; Purnendu, K.D.

    2003-01-01

    Two different measurement methods for atmospheric nitric and nitrous acid during the Atlanta Supersite study are described and compared. Both approaches combined wet denuder collection coupled to ion chromatographic analysis. One of these utilized a rotating wet annular denuder maintained indoor wit

  10. Brightening of the global cloud field by nitric acid and the associated radiative forcing

    Directory of Open Access Journals (Sweden)

    R. Makkonen

    2012-08-01

    Full Text Available Clouds cool Earth's climate by reflecting 20% of the incoming solar energy, while also trapping part of the outgoing radiation. The effect of human activities on clouds is poorly understood, but the present-day anthropogenic cooling via changes of cloud albedo and lifetime could be of the same order as warming from anthropogenic addition in CO2. Soluble trace gases can increase water condensation to particles, possibly leading to activation of smaller aerosols and more numerous cloud droplets. We have studied the effect of nitric acid on the aerosol indirect effect with the global aerosol-climate model ECHAM5.5-HAM2. Including the nitric acid effect in the model increases cloud droplet number concentrations globally by 7%. The nitric acid contribution to the present-day cloud albedo effect was found to be −0.32 W m−2 and to the total indirect effect −0.46 W m−2. The contribution to the cloud albedo effect is shown to increase to −0.37 W m−2 by the year 2100, if considering only the reductions in available cloud condensation nuclei. Overall, the effect of nitric acid can play a large part in aerosol cooling during the following decades with decreasing SO2 emissions and increasing NOx and greenhouse gases.

  11. Nitric acid-organic mixtures surveyed for use in separation by anion exchange methods

    Science.gov (United States)

    Bloomquist, C. A. A.; Faris, J. P.; Stewart, D. C.

    1968-01-01

    Column elution-spectrographic analysis technique compares certain solvents directly to the methanol system, using inert rare earths instead of actinides. Distribution ratios for americium between 90 percent solvent, 10 percent 5 M nitric acid and Dowex 1 nitrate form resin for a large group of organics miscible in water was determined.

  12. 77 FR 48433 - New Source Performance Standards Review for Nitric Acid Plants

    Science.gov (United States)

    2012-08-14

    ... standards for nitric acid plants, contact Mr. Nathan Topham, Sector Policies and Program Division, Office of... Industry 325311 Nitrogenous Fertilizer Manufacturing. Federal government Not affected. State/local/tribal... seeking to make such a demonstration to us should submit a Petition for Reconsideration to the Office of...

  13. Photosynthetic and growth responses of Schima superba seedlings to sulfuric and nitric acid depositions.

    Science.gov (United States)

    Yao, Fang-Fang; Ding, Hui-Ming; Feng, Li-Li; Chen, Jing-Jing; Yang, Song-Yu; Wang, Xi-Hua

    2016-05-01

    A continuing rise in acid deposition can cause forest degradation. In China, acid deposition has converted gradually from sulfuric acid deposition (SAD) to nitric acid deposition (NAD). However, the differing responses of photosynthesis and growth to depositions of sulfuric vs. nitric acid have not been well studied. In this study, 1-year-old seedlings of Schima superba, a dominant species in subtropical forests, were treated with two types of acid deposition SO4 (2-)/NO3 (-) ratios (8:1 and 0.7:1) with two applications (foliar spraying and soil drenching) at two pH levels (pH 3.5 and pH 2.5) over a period of 18 months. The results showed that the intensity, acid deposition type, and spraying method had significant effects on the physiological characteristics and growth performance of seedlings. Acid deposition at pH 2.5 via foliar application reduced photosynthesis and growth of S. superba, especially in the first year. Unlike SAD, NAD with high acidity potentially alleviated the negative effects of acidity on physiological properties and growth, probably due to a fertilization effect that improved foliar nitrogen and chlorophyll contents. Our results suggest that trees were damaged mainly by direct acid stress in the short term, whereas in the long term, soil acidification was also likely to be a major risk to forest ecosystems. Our data suggest that the shift in acid deposition type may complicate the ongoing challenge of anthropogenic acid deposition to ecosystem stability.

  14. The Consistency of Isotopologues of Ambient Atmospheric Nitric Acid in Passively Collected Samples

    Science.gov (United States)

    Bell, M. D.; Sickman, J. O.; Bytnerowicz, A.; Padgett, P.; Allen, E. B.

    2012-12-01

    Anthropogenic sources of nitrogen oxides have previously been shown to have distinctive isotopic signatures of oxygen and nitrogen. Nylon filters are currently used in passive sampling arrays to measure ambient atmospheric nitric acid concentrations and estimate deposition rates. This experiment measured the ability of nylon filters to consistently collect isotopologues of atmospheric nitric acid in the same ratios as they are present in the atmosphere. Samplers were deployed in continuous stirred tank reactors (CSTR) and at field sites across a nitrogen deposition gradient in Southern California. Filters were exposed over a four week period with individual filters being subjected to 1-4 week exposure times. Extracted nitric acid were measured for δ18O and δ15N ratios and compared for consistency based on length of exposure and amount of HNO3 collected. Filters within the CSTRs collected HNO3 at a consistent rate in both high and low concentration chambers. After two weeks of exposure, the mean δ18O values were within 0.5‰ of the δ18O of the source HNO3 solution. The mean of all weekly exposures were within 0.5‰ of the δ15N of the source solution, but after three weeks, the mean δ15N of adsorbed HNO3 was within 0.2‰. As the length of the exposure increased, the variability of measured delta values decreased for both elements. The field samplers collected HNO3 consistent with previously measured values along a deposition gradient. The mean δ18O at high deposition sites was 52.2‰ compared to 35.7‰ at the low deposition sites. Mean δ15N values were similar at all sites across the deposition gradient. Due to precipitation events occurring during the exposure period, the δ15N and δ18O of nitric acid were highly variable at all field sites. At single sites, changes in δ15N and δ18O were negatively correlated, consistent with two-sourcing mixing dynamics, but the slope of the regressions differed between high and low deposition sites. Anthropogenic

  15. Influence of Nitric Acid Concentration on Characteristics of Olive Stone Based Activated Carbon

    Institute of Scientific and Technical Information of China (English)

    Nouha Soudani; Souad Souissi-najar; Abdelmottaleb Ouederni

    2013-01-01

    In this work we investigated the effect of nitric acid concentration on the pore structure, surface chemis-try and liquid phase adsorption of olive stone based activated carbon prepared by mixing process using phosphoric acid and steam as activating agents. Chemicals and textural characterization show that the increase of HNO3 con-centration increases considerably the total acidic groups but decreases specific surface area and pore volume. The study of adsorption in aqueous solutions of two organics, phenol and methylene blue, on raw and oxidized activated carbon indicates that the treatment of mixed activated carbon with different concentrations of nitric acid improves the adsorbent capacity for methylene blue at HNO3 concentrations less or equal to 2 mol·L-1, while it has a negative effect on phenol adsorption.

  16. Nitric acid treated multi-walled carbon nanotubes optimized by Taguchi method

    Science.gov (United States)

    Shamsuddin, Shahidah Arina; Derman, Mohd Nazree; Hashim, Uda; Kashif, Muhammad; Adam, Tijjani; Halim, Nur Hamidah Abdul; Tahir, Muhammad Faheem Mohd

    2016-07-01

    Electron transfer rate (ETR) of CNTs can be enhanced by increasing the amounts of COOH groups to their wall and opened tips. With the aim to achieve the highest production amount of COOH, Taguchi robust design has been used for the first time to optimize the surface modification of MWCNTs by nitric acid oxidation. Three main oxidation parameters which are concentration of acid, treatment temperature and treatment time have been selected as the control factors that will be optimized. The amounts of COOH produced are measured by using FTIR spectroscopy through the absorbance intensity. From the analysis, we found that acid concentration and treatment time had the most important influence on the production of COOH. Meanwhile, the treatment temperature will only give intermediate effect. The optimum amount of COOH can be achieved with the treatment by 8.0 M concentration of nitric acid at 120 °C for 2 hour.

  17. Nitric Acid Revamp and Upgrading of the Alarm & Protection Safety System at Petrokemija, Croatia

    Directory of Open Access Journals (Sweden)

    Hoško, I.

    2012-04-01

    Full Text Available Every industrial production, particularly chemical processing, demands special attention in conducting the technological process with regard to the security requirements. For this reason, production processes should be continuously monitored by means of control and alarm safety instrumented systems. In the production of nitric acid at Petrokemija d. d., the original alarm safety system was designed as a combination of an electrical relay safety system and transistorized alarm module system. In order to increase safety requirements and modernize the technological process of nitric acid production, revamping and upgrading of the existing alarm safety system was initiated with a new microprocessor system. The newly derived alarm safety system, Simatic PCS 7, links the function of "classically" distributed control (DCS and logical systems in a common hardware and software platform with integrated engineering tools and operator interface to meet the minimum safety standards with safety integrity level 2 (SIL2 up to level 3 (SIL3, according to IEC 61508 and IEC 61511. This professional paper demonstrates the methodology of upgrading the logic of the alarm safety system in the production of nitric acid in the form of a logical diagram, which was the basis for a further step in its design and construction. Based on the mentioned logical diagram and defined security requirements, the project was implemented in three phases: analysis and testing, installation of the safety equipment and system, and commissioning. Developed also was a verification system of all safety conditions, which could be applied to other facilities for production of nitric acid. With the revamped and upgraded interlock alarm safety system, a new and improved safety boundary in the production of nitric acid was set, which created the foundation for further improvement of the production process in terms of improved analysis.

  18. KINETIC STUDIES ON THE POLYMERIZATION OF ACRYLONITRILE INITIATED BY METALLIC MAGNESIUM-NITRIC ACID SYSTEM

    Institute of Scientific and Technical Information of China (English)

    WU Chinyung

    1983-01-01

    This article reports the polymerization kinetics of acrylonitrile initiated by metallic magnesiumnitric acid system. The rate of polymerization is independent of the amount of magnesium used; when the concentration of nitric acid is higher than acrylonitrile, the equation of polymerization kinetics may be expressed as Rp=1.91 × 105e-15000/RT[Mg]0 [AN]2·2 [HNO3]0·46 The result of copolymerization of acyrlonitrile and methyl acrylate supports a free-radical mechanism.

  19. Integrating nitric oxide into salicylic acid and jasmonic acid/ ethylene plant defense pathways.

    Science.gov (United States)

    Mur, Luis A J; Prats, Elena; Pierre, Sandra; Hall, Michael A; Hebelstrup, Kim H

    2013-01-01

    Plant defense against pests and pathogens is known to be conferred by either salicylic acid (SA) or jasmonic acid (JA)/ethylene (ET) pathways, depending on infection or herbivore-grazing strategy. It is well attested that SA and JA/ET pathways are mutually antagonistic allowing defense responses to be tailored to particular biotic stresses. Nitric oxide (NO) has emerged as a major signal influencing resistance mediated by both signaling pathways but no attempt has been made to integrate NO into established SA/JA/ET interactions. NO has been shown to act as an inducer or suppressor of signaling along each pathway. NO will initiate SA biosynthesis and nitrosylate key cysteines on TGA-class transcription factors to aid in the initiation of SA-dependent gene expression. Against this, S-nitrosylation of NONEXPRESSOR OF PATHOGENESIS-RELATED PROTEINS1 (NPR1) will promote the NPR1 oligomerization within the cytoplasm to reduce TGA activation. In JA biosynthesis, NO will initiate the expression of JA biosynthetic enzymes, presumably to over-come any antagonistic effects of SA on JA-mediated transcription. NO will also initiate the expression of ET biosynthetic genes but a suppressive role is also observed in the S-nitrosylation and inhibition of S-adenosylmethionine transferases which provides methyl groups for ET production. Based on these data a model for NO action is proposed but we have also highlighted the need to understand when and how inductive and suppressive steps are used.

  20. Integrating nitric oxide into salicylic acid and jasmonic acid/ ethylene plant defence pathways.

    Directory of Open Access Journals (Sweden)

    Luis A.J. Mur

    2013-06-01

    Full Text Available Plant defence against pests and pathogens is known to be conferred by either salicylic acid (SA or jasmonic acid (JA/ethylene (ET pathways, depending on infection or herbivore-grazing strategy. It is well attested that SA and JA/ET pathways are mutually antagonistic allowing defence responses to be tailored to particular biotic stresses. Nitric oxide (NO has emerged as a major signal influencing resistance mediated by both signalling pathways but no attempt has been made to integrate NO into established SA/JA/ET interactions. NO has been shown to act as an inducer or suppressor of signalling along each pathway. NO will initiate SA biosynthesis and nitrosylate key cysteines on TGA-class transcription factors to aid in the initiation of SA—dependent gene expression. Against this, S-nitrosylation of NONEXPRESSOR OF PATHOGENESIS-RELATED PROTEINS1 (NPR1 will promote the NPR1 oligomerisation within the cytoplasm to reduce TGA activation. In JA biosynthesis, NO will initiate the expression of JA biosynthetic enzymes, presumably to over-come any antagonistic effects of SA on JA-mediated transcription. NO will also initiate the expression of ET biosynthetic genes but a suppressive role is also observed in the S –nitrosylation and inhibition of s-adenosylmethionine transferases which provides methyl groups for ethylene production. Based on these data a model for NO action is proposed but we have also highlighted the need to understand when and how inductive and suppressive steps are used.

  1. Improvement in electrochemical capacitance of activated carbon from scrap tires by nitric acid treatment

    Science.gov (United States)

    Han, Yan; Zhao, Ping-Ping; Dong, Xiao-Ting; Zhang, Cui; Liu, Shuang-Xi

    2014-12-01

    Activated carbon (AC) obtained from the industrial pyrolytic tire char is treated by concentrated nitric acid (AC-HNO3) and then used as the electrode material for supercapacitors. Surface properties and electrochemical capacitances of AC and ACHNO3 are studied. It is found that the morphology and the porous texture for AC and AC-HNO3 have little difference, while the oxygen content increases and functional groups change after the acid treatment. Electrochemical results demonstrate that the AC-HNO3 electrode displays higher specific capacitance, better stability and cycling performance, and lower equivalent series resistance, indicating that AC obtained from the industrial pyrolytic tire char treated by concentrated nitric acid is applicable for supercapacitors.

  2. Extractive distillation of nitric acid using the two-pot concept

    Energy Technology Data Exchange (ETDEWEB)

    Counce, R.M.; Groenier, W.S.; Holland, W.D.; Jubin, R.T.; North, E.D.; Thompson, L.E. Jr.; Hebble, T.L.

    1982-12-01

    Experiments have confirmed the validity of a novel design for a nitric acid concentration system for use in shielded nuclear fuel reprocessing plants. Current plans for producing the scrub solution for the IODOX process require the concentration and recycle of low strength (< 68.5 wt %) nitric acid sources. The described system utilizes extractive distillation with Mg(NO/sub 3/)/sub 2/ as the solvent and features two pots: an extractive distillation pot in which a concentrated acid product is obtained by contacting the acid feed with the solvent and a solvent recovery pot in which the solvent is dehydrated and recovered for recycle. In these experiments, a concentrated product of 89 wt % nitric acid was produced from azeotropic feed. The available vapor-liquid equilibria data for the Mg(NO/sub 3/)/sub 2/-HNO/sub 3/-H/sub 2/O system has been empirically correlated, and a design methodology has been developed for the two-pot extractive distillation process.

  3. Multivariate analysis for quantification of Plutonium (IV) in nitric acid based on absorption spectra

    Energy Technology Data Exchange (ETDEWEB)

    Lines, Amanda M.; Adami, Susan R.; Sinkov, Sergey I.; Lumetta, Gregg J.; Bryan, Samuel A.

    2017-07-20

    Development of more effective, reliable, and fast methods for monitoring process streams is a growing opportunity for analytical applications. Many fields can benefit from on-line monitoring, including the nuclear fuel cycle where improved methods for monitoring radioactive materials will facilitate maintenance of proper safeguards and ensure safe and efficient processing of materials. On-line process monitoring with a focus on optical spectroscopy can provide a fast, non-destructive method for monitoring chemical species. However, identification and quantification of species can be hindered by the complexity of the solutions if bands overlap or show condition-dependent spectral features. Plutonium (IV) is one example of a species which displays significant spectral variation with changing nitric acid concentration. Single variate analysis (i.e. Beer’s Law) is difficult to apply to the quantification of Pu(IV) unless the nitric acid concentration is known and separate calibration curves have been made for all possible acid strengths. Multivariate, or chemometric, analysis is an approach that allows for the accurate quantification of Pu(IV) without a priori knowledge of nitric acid concentration.

  4. Nitric Acid-Treated Carbon Fibers with Enhanced Hydrophilicity for Candida tropicalis Immobilization in Xylitol Fermentation

    Directory of Open Access Journals (Sweden)

    Le Wang

    2016-03-01

    Full Text Available Nitric acid (HNO3-treated carbon fiber (CF rich in hydrophilic groups was applied as a cell-immobilized carrier for xylitol fermentation. Using scanning electron microscopy, we characterized the morphology of the HNO3-treated CF. Additionally, we evaluated the immobilized efficiency (IE of Candida tropicalis and xylitol fermentation yield by investigating the surface properties of nitric acid treated CF, specifically, the acidic group content, zero charge point, degree of moisture and contact angle. We found that adhesion is the major mechanism for cell immobilization and that it is greatly affected by the hydrophilic–hydrophilic surface properties. In our experiments, we found 3 hto be the optimal time for treating CF with nitric acid, resulting in an improved IE of Candida tropicalis of 0.98 g∙g−1 and the highest xylitol yield and volumetric productivity (70.13% and 1.22 g∙L−1∙h−1, respectively. The HNO3-treated CF represents a promising method for preparing biocompatible biocarriers for multi-batch fermentation.

  5. Extraction behaviour of Am(III) and Eu(III) from nitric acid medium in TEHDGA-HDEHP impregnated resins

    Energy Technology Data Exchange (ETDEWEB)

    Saipriya, G.; Kumar, T. [Bhabha Atomic Research Centre Facilities, Kalpakkam (India). Kalpakkam Reprocessing Plant; Kumaresan, R.; Nayak, P.K.; Venkatesan, K.A.; Antony, M.P. [Indira Gandhi Center for Atomic Research, Kalpakkam (India). Fuel Chemistry Div.

    2016-07-01

    The extraction behaviour of Am(III) and Eu(III) from nitric acid medium was studied in the solvent impregnated resins containing extractants such as tetra-bis(2-ethylhexyl)diglycolamide (TEHDGA) or bis-(2-ethylhexyl)phosphoric acid (HDEHP) or mixture of TEHDGA+HDEHP. The rate of extraction of Am(III) and Eu(III) from 1 M nitric acid and the effect of various parameters, such as the concentration of nitric acid in aqueous phase and concentration of TEHDGA and HDEHP in resin phase, on the distribution coefficient of Am(III) and Eu(III) was studied. The distribution coefficient of Am(III) and Eu(III) in HDEHP-impregnated resin decreased and that in TEHDGA-impregnated resin increased, with increase in the concentration of nitric acid. However, in (TEHDGA+HDEHP) - impregnated resin, synergic extraction was observed at lower nitric acid concentration and antagonism at higher nitric acid concentration. The mechanism of Am(III) and Eu(III) extraction in the combined resin was investigated by slope analysis method. The extraction of various metal ions present in the fast reactor simulated high-level liquid waste was studied. The separation factor of Am(III) over Eu(III) was studied using citrate-buffered diethylenetriaminepentaacetic acid (DTPA) solution.

  6. Oleic acid-dependent modulation of Nitric oxide associated 1 protein levels regulates nitric oxide-mediated defense signaling in Arabidopsis

    Science.gov (United States)

    The conserved cellular metabolites nitric oxide (NO) and oleic acid (18:1) are well-known regulators of disease physiologies in diverse organism. We show that NO production in plants is regulated via 18:1. Reduction in 18:1 levels, via a genetic mutation in the 18:1-synthesizing gene SUPPRESSOR OF S...

  7. Evaluation of the Magnesium Hydroxide Treatment Process for Stabilizing PFP Plutonium/Nitric Acid Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Gerber, Mark A.; Schmidt, Andrew J.; Delegard, Calvin H.; Silvers, Kurt L.; Baker, Aaron B.; Gano, Susan R.; Thornton, Brenda M.

    2000-09-28

    This document summarizes an evaluation of the magnesium hydroxide [Mg(OH)2] process to be used at the Hanford Plutonium Finishing Plant (PFP) for stabilizing plutonium/nitric acid solutions to meet the goal of stabilizing the plutonium in an oxide form suitable for storage under DOE-STD-3013-99. During the treatment process, nitric acid solutions bearing plutonium nitrate are neutralized with Mg(OH)2 in an air sparge reactor. The resulting slurry, containing plutonium hydroxide, is filtered and calcined. The process evaluation included a literature review and extensive laboratory- and bench-scale testing. The testing was conducted using cerium as a surrogate for plutonium to identify and quantify the effects of key processing variables on processing time (primarily neutralization and filtration time) and calcined product properties.

  8. Easy synthesis of graphene sheets from alfalfa plants by treatment of nitric acid

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Jiao, E-mail: qujiao@bhu.edu.cn [School of Chemistry and Chemical Engineering, Bohai University, Jinzhou 121013 (China); School of Urban and Environmental Sciences, Northeast Normal University, Changchun 130024 (China); Luo, Chunqiu, E-mail: fplj_lcq@163.com [School of Chemistry and Chemical Engineering, Bohai University, Jinzhou 121013 (China); Zhang, Qian; Cong, Qiao [School of Chemistry and Chemical Engineering, Bohai University, Jinzhou 121013 (China); Yuan, Xing [School of Urban and Environmental Sciences, Northeast Normal University, Changchun 130024 (China)

    2013-04-01

    Highlights: ► An easy method for synthesis of graphene sheets using alfalfa plants was introduced. ► An novelty formation mechanism of graphene sheets using alfalfa plants was proposed. ► This method exploits a new carbon source and provides a novel idea to synthesize graphene sheets. -- Abstract: This letter focuses on synthesis of graphene sheets from alfalfa plants by treatment of nitric acid. The transmission electron microscopy image (TEM) demonstrates that the graphene sheets are agglomerated and overlapped, the energy dispersive spectrum (EDS) indicates that the products are pure, and the Raman spectrum shows the graphene sheets are well graphitized. In addition, the formation mechanism of the graphene sheets from alfalfa plants by treatment nitric acid is discussed. These findings inspire the search for a new strategy for synthesis of graphene sheets from renewable natural products, and the lower cost of this new process and carbon source may facilitate industrial production.

  9. Effect of Different Electrode Materials on the Electropolymerization Process of Aniline in Nitric Acid Media

    Science.gov (United States)

    Li, Yaozong; Yi, Yun; Yang, Weifang; Liu, Xiaoqing; Li, Yuanyuan; Wang, Wei

    2016-11-01

    The electropolymerization process of aniline on different electrode surfaces such as Pt, Au, RuTi and polyaniline film in nitric acid solution containing 1 M aniline was investigated by cyclic voltammetry and electrochemical impedance spectroscopy. Proposed electrical equivalent circuits were used to give a further analysis. Results show that the electrode materials accelerate the aniline electropolymerization remarkably as a catalyst, especially the electrochemical oxidation process of monomer aniline to its cation radical, which is the key step to incur the electropolymerization reaction of aniline on the electrode surface. The polymerization of aniline on RuTi electrode has the lowest reaction resistance for its adsorption sites, and the catalytic effects of these different electrodes decrease in the order: RuTi > polyaniline film > Pt > Au. The results also show that several states of polyaniline films are formed during the potential linear scan process in nitric acid solution and the corresponding oxidation and reduction reaction are reversible.

  10. Effect of Different Electrode Materials on the Electropolymerization Process of Aniline in Nitric Acid Media

    Science.gov (United States)

    Li, Yaozong; Yi, Yun; Yang, Weifang; Liu, Xiaoqing; Li, Yuanyuan; Wang, Wei

    2017-02-01

    The electropolymerization process of aniline on different electrode surfaces such as Pt, Au, RuTi and polyaniline film in nitric acid solution containing 1 M aniline was investigated by cyclic voltammetry and electrochemical impedance spectroscopy. Proposed electrical equivalent circuits were used to give a further analysis. Results show that the electrode materials accelerate the aniline electropolymerization remarkably as a catalyst, especially the electrochemical oxidation process of monomer aniline to its cation radical, which is the key step to incur the electropolymerization reaction of aniline on the electrode surface. The polymerization of aniline on RuTi electrode has the lowest reaction resistance for its adsorption sites, and the catalytic effects of these different electrodes decrease in the order: RuTi > polyaniline film > Pt > Au. The results also show that several states of polyaniline films are formed during the potential linear scan process in nitric acid solution and the corresponding oxidation and reduction reaction are reversible.

  11. Passive Sampler for Measurements of Atmospheric Nitric Acid Vapor (HNO3 Concentrations

    Directory of Open Access Journals (Sweden)

    Andrzej Bytnerowicz

    2001-01-01

    Full Text Available Nitric acid (HNO3 vapor is an important nitrogenous air pollutant responsible for increasing saturation of forests with nitrogen and direct injury to plants. The USDA Forest Service and University of California researchers have developed a simple and inexpensive passive sampler for monitoring air concentrations of HNO3. Nitric acid is selectively absorbed on 47-mm Nylasorb nylon filters with no interference from particulate NO3-. Concentrations determined with the passive samplers closely corresponded with those measured with the co-located honeycomb annular denuder systems. The PVC protective caps of standardized dimensions protect nylon filters from rain and wind and allow for reliable measurements of ambient HNO3 concentrations. The described samplers have been successfully used in Sequoia National Park, the San Bernardino Mountains, and on Mammoth Mountain in California.

  12. Procedure of Destructive Chemical Recovery of Precious Metals in Nitric Acid Production

    OpenAIRE

    Ljubičić, M.; Zečević, N.

    2012-01-01

    The heart of the nitric acid production process is the chemical reactor containing a platinum-based catalyst pack and an associated catchment system, which allows the ammonia oxidation reaction to take place efficiently. Under the severe operating conditions imposed by the high-pressure ammonia oxidation process, the catalyst gauzes experience progressive deterioration, as shown by the restricted surface of the catalyst wires, the loss of catalytic activity and the loss of catalytic materials...

  13. Study on the Reaction Between Methyl Hydrazine and Formaldehyde in Nitric Acid Medium

    Institute of Scientific and Technical Information of China (English)

    LI; Chuan-bo; CAO; Zhi; BIAN; Xiao-yan; XIAN; Liang; YAN; Tai-hong; ZHENG; Wei-fang

    2012-01-01

    <正>To make sure whether the reaction between formaldehyde and methyl hydrazine (MMH) could happen in dilute nitric acid solution, the condensation reaction between the two ones was investigated at 16 ℃. The reaction was slow and it took over 5 hours to reach the balance and the solution turned yellow at last. The maximum absorption peaks of the product existed at 340 nm and 400-450 nm, respectively.

  14. Search for an in-line nitric acid analyzer

    Energy Technology Data Exchange (ETDEWEB)

    Gallagher, K. Y.; Johnson, C. M.

    1980-10-01

    A literature search was conducted to identify possible techniques for measuring mineral acid normality in the presence of heavy metal salts, undissolved solids, and high radiation fields. Of the techniques noted, eight were identified that could be applicable to the objective. The possibilities were reduced to two methods, which warrant further investigation. These two are refractometry and a modified coulometric-polarographic method. All methods are discussed in detail followed by rationale for including or rejecting each for further investigation.

  15. Extraction behaviour of Am(III) and Eu(III) from nitric acid medium in CMPO-HDEHP impregnated resins

    Energy Technology Data Exchange (ETDEWEB)

    Saipriya, K.; Kumar, T. [Bhabha Atomic Research Centre Facilities (India). Kalpakkam Reproscessing Plants; Kumaresan, R.; Nayak, P.K.; Venkatesan, K.A.; Antony, M.P. [Indira Gandhi Center for Atomic Research, Kalpakkam (India). Fuel Chemistry Div.

    2016-05-01

    Chromatographic resin containing extractants such as octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) or bis-(2-ethylhexyl)phosphoric acid (HDEHP) or mixture of extractants (CMPO + HDEHP) in an acrylic polymer matrix was prepared and studied for the extraction of Am(III) and Eu(III) over a range of nitric acid concentration. The effect of various parameters such as concentration of nitric acid in aqueous phase and the concentration of CMPO and HDEHP in the resin phase was studied. The distribution coefficient of Am(III) and Eu(III) in the impregnated resin increased with increased in the concentration of nitric acid for CMPO-impregnated resin, whereas a reverse trend was observed in HDEHP impregnated resin. In case of resin containing both the extractants, synergism was observed at low nitric acid concentration and antagonism at high nitric acid concentration. The mechanism of extraction was probed by slope analysis method at 0.01 and 2 M nitric acid concentrations. Citrate-buffered DTPA was used for the selective separation of Am(III), and a separation factor of 3-4 was obtained at pH 3.

  16. Quantitative analysis of mixed hydrofluoric and nitric acids using Raman spectroscopy with partial least squares regression.

    Science.gov (United States)

    Kang, Gumin; Lee, Kwangchil; Park, Haesung; Lee, Jinho; Jung, Youngjean; Kim, Kyoungsik; Son, Boongho; Park, Hyoungkuk

    2010-06-15

    Mixed hydrofluoric and nitric acids are widely used as a good etchant for the pickling process of stainless steels. The cost reduction and the procedure optimization in the manufacturing process can be facilitated by optically detecting the concentration of the mixed acids. In this work, we developed a novel method which allows us to obtain the concentrations of hydrofluoric acid (HF) and nitric acid (HNO(3)) mixture samples with high accuracy. The experiments were carried out for the mixed acids which consist of the HF (0.5-3wt%) and the HNO(3) (2-12wt%) at room temperature. Fourier Transform Raman spectroscopy has been utilized to measure the concentration of the mixed acids HF and HNO(3), because the mixture sample has several strong Raman bands caused by the vibrational mode of each acid in this spectrum. The calibration of spectral data has been performed using the partial least squares regression method which is ideal for local range data treatment. Several figures of merit (FOM) were calculated using the concept of net analyte signal (NAS) to evaluate performance of our methodology.

  17. Kinetics of Reaction Between Tc(Ⅶ) and Monomethylhydrazine or Dimethylhydroxylamine in Nitric Acid Medium Containing Plutonium

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>The chemical reaction kinetics research of Tc(Ⅶ) with monomethylhydrazine or dimethylhydroxy-lamine in nitric acid medium demonstrated that Tc(Ⅶ) hardly reacts with the salt-free reagents during the

  18. Thermal decomposition of organic solvent with nitric acid in nuclear fuel reprocessing plants

    Energy Technology Data Exchange (ETDEWEB)

    Koike, Tadao; Nishio, Gunji; Takada, Junichi; Tukamoto, Michio; Watanabe, Kouji [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Miyata, Sadaichirou

    1995-02-01

    Since a thermal decomposition of organic solvent containing TBP (tributyl phosphate) with nitric acid and heavy metal nitrates is an exothermic reaction, it is possible to cause an explosive decomposition of TBP-complex materials formed by a nitration between the solvent and nitric acid, if the solvent involving TBP-complex is heated upto a thermal limit in an evaporator to concentrate a fuel liquid solution from the extraction process in the reprocessing plant. In JAERI, the demonstration test for explosive decomposition of TBP-complex by the nitration was performed to elucidate the safety margin of the evaporator in the event of hypothetical explosion under auspices of the Science and Technology Agency. The demonstration test was carried out by heating TBP/n-dodecane solvent mixed with nitric acid and uranium nitrate. In the test, the thermal decomposition behavior of the solvent was examined, and also a kinematic reaction constant and a heat formation of the TBP-complex decomposition were measured by the test. In the paper, a safety analysis of a model evaporator was conducted during accidental conditions under the explosive decomposition of the solvent. (author).

  19. Fumes from shotfiring

    Energy Technology Data Exchange (ETDEWEB)

    Carbonel, P.; Bigourd, J.; Dangreaux, J.

    1980-07-01

    Fumes arising from shotfiring explosives contain a variety of toxic substances depending on the type of explosive used. CERCHAR is studying several test methods for assessing the amounts of these toxic gases. The test conditions, which are varied systematically, have a large effect on the amount of gas produced by a given explosive. Describes 115 l bomb tests and tests in a chamber (15 m3). Presents a comparison with real shotfiring operations underground. The tests in the 15 m3 chamber gave results which were very close to operating practice. (In French)

  20. Supercritical fluid extraction of uranium and thorium from nitric acid medium using organophosphorous compounds

    Energy Technology Data Exchange (ETDEWEB)

    Pitchaiah, K.C.; Sujatha, K.; Rao, C.V.S. Brahmmananda; Subramaniam, S.; Sivaraman, N.; Rao, P.R. Vasudeva [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Chemistry Group

    2015-06-01

    In recent years, Supercritical Fluid Extraction (SFE) technique has been widely used for the extraction of metal ions. In the present study, extraction of uranium from nitric acid medium was investigated using supercritical carbon dioxide (Sc-CO{sub 2}) containing various organophosphorous compounds such as trialkyl phosphates e.g. tri-iso-amyl phosphate (TiAP), tri-sec-butyl phosphate (TsBP) and tri-n-butyl phosphate (TBP), dialkylalkyl phosphonates, e.g. diamylamyl phosphonate (DAAP) and dibutyl butyl phosphonate (DBBP), dialkyl hydrogen phosphonates, e.g. dioctyl hydrogen phosphonate (DOHP), dioctylphosphineoxide (DOPO), trioctyl phosphine oxide (TOPO), n-octylphenyl N,N-diisobutyl carbamoylmethylphosphine oxide (CMPO) and di-2-ethyl-hexyl phosphoric acid (HDEHP). Some of these ligands have been investigated for the first time in the supercritical phase for the extraction of uranium. The extraction efficiency of uranium was studied with TiAP, DAAP and DBBP as a function of nitric acid concentration; the kinetics of the equilibration period (static extraction) and transportation of the metal complex (dynamic extraction) was investigated. The influence of pressure and temperature on the extraction behaviour of uranium with DAAP was studied from 4 N HNO{sub 3}. The extraction efficiency of uranium from 4 N nitric acid medium was found to increase in the order of phosphates < phosphonates < HDEHP < TOPO < CMPO. In the case of phosphates and phosphonates, the maximum extraction of uranium was found to be from 4 N HNO{sub 3} medium. The acidic extractants, HDEHP and DOHP showed relatively higher extraction at lower acidities. The relative extraction of uranium and thorium from their mixture was also examined using Sc-CO{sub 2} containing phosphates, phosphonates and TOPO. The ligand, TsBP provided better fractionation between uranium and thorium compared to trialkyl phosphates, dialkyl alkyl phosphonates and TOPO.

  1. Sludge batch 9 simulant runs using the nitric-glycolic acid flowsheet

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, D. P. [Savannah River Site (SRS), Aiken, SC (United States); Williams, M. S. [Savannah River Site (SRS), Aiken, SC (United States); Brandenburg, C. H. [Savannah River Site (SRS), Aiken, SC (United States); Luther, M. C. [Savannah River Site (SRS), Aiken, SC (United States); Newell, J. D. [Savannah River Site (SRS), Aiken, SC (United States); Woodham, W. H. [Savannah River Site (SRS), Aiken, SC (United States)

    2016-11-01

    Testing was completed to develop a Sludge Batch 9 (SB9) nitric-glycolic acid chemical process flowsheet for the Defense Waste Processing Facility’s (DWPF) Chemical Process Cell (CPC). CPC simulations were completed using SB9 sludge simulant, Strip Effluent Feed Tank (SEFT) simulant and Precipitate Reactor Feed Tank (PRFT) simulant. Ten sludge-only Sludge Receipt and Adjustment Tank (SRAT) cycles and four SRAT/Slurry Mix Evaporator (SME) cycles, and one actual SB9 sludge (SRAT/SME cycle) were completed. As has been demonstrated in over 100 simulations, the replacement of formic acid with glycolic acid virtually eliminates the CPC’s largest flammability hazards, hydrogen and ammonia. Recommended processing conditions are summarized in section 3.5.1. Testing demonstrated that the interim chemistry and Reduction/Oxidation (REDOX) equations are sufficient to predict the composition of DWPF SRAT product and SME product. Additional reports will finalize the chemistry and REDOX equations. Additional testing developed an antifoam strategy to minimize the hexamethyldisiloxane (HMDSO) peak at boiling, while controlling foam based on testing with simulant and actual waste. Implementation of the nitric-glycolic acid flowsheet in DWPF is recommended. This flowsheet not only eliminates the hydrogen and ammonia hazards but will lead to shorter processing times, higher elemental mercury recovery, and more concentrated SRAT and SME products. The steady pH profile is expected to provide flexibility in processing the high volume of strip effluent expected once the Salt Waste Processing Facility starts up.

  2. Coordination leaching of tungsten from scheelite concentrate with phosphorus in nitric acid

    Institute of Scientific and Technical Information of China (English)

    张文娟; 杨金洪; 赵中伟; 王文强; 李江涛

    2016-01-01

    A hydrometallurgical process for tungsten extraction and recovery from scheelite is reported. The technology includes leaching scheelite using phosphoric acid as chelating agent in nitric acid solutions, extracting tungsten by solvent extraction and reusing leaching agent. In the leaching process, affecting factors, such as temperature, leaching time, nitric acid and dosage of phosphoric acid, were examined on recovery of tungsten. Results show that more than 97% of tungsten could be extracted under conditions of leaching temperature of 80−90 °C, HNO3 concentration of 3.0−4.0 mol/L, liquild-to-soild ratio of 10:1, H3PO4 dosage of 3 stoichiometric ratio and leaching time of 3 h. Solvent extraction was then employed for the W recovery from the leachate with a organic system of 40%(v/v) N235, 30%(v/v) TBP, and 30%sulfonated kerosene. Approximately 99.93%of W was extracted and ammonium tungstate solution containing 193 g/L W was obtained with a stripping rate of 98.10%under the optimized conditions.

  3. FY13 GLYCOLIC-NITRIC ACID FLOWSHEET DEMONSTRATIONS OF THE DWPF CHEMICAL PROCESS CELL WITH SIMULANTS

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, D.; Zamecnik, J.; Best, D.

    2014-03-13

    Savannah River Remediation is evaluating changes to its current Defense Waste Processing Facility flowsheet to replace formic acid with glycolic acid in order to improve processing cycle times and decrease by approximately 100x the production of hydrogen, a potentially flammable gas. Higher throughput is needed in the Chemical Processing Cell since the installation of the bubblers into the melter has increased melt rate. Due to the significant maintenance required for the safety significant gas chromatographs and the potential for production of flammable quantities of hydrogen, eliminating the use of formic acid is highly desirable. Previous testing at the Savannah River National Laboratory has shown that replacing formic acid with glycolic acid allows the reduction and removal of mercury without significant catalytic hydrogen generation. Five back-to-back Sludge Receipt and Adjustment Tank (SRAT) cycles and four back-to-back Slurry Mix Evaporator (SME) cycles were successful in demonstrating the viability of the nitric/glycolic acid flowsheet. The testing was completed in FY13 to determine the impact of process heels (approximately 25% of the material is left behind after transfers). In addition, back-to-back experiments might identify longer-term processing problems. The testing was designed to be prototypic by including sludge simulant, Actinide Removal Product simulant, nitric acid, glycolic acid, and Strip Effluent simulant containing Next Generation Solvent in the SRAT processing and SRAT product simulant, decontamination frit slurry, and process frit slurry in the SME processing. A heel was produced in the first cycle and each subsequent cycle utilized the remaining heel from the previous cycle. Lower SRAT purges were utilized due to the low hydrogen generation. Design basis addition rates and boilup rates were used so the processing time was shorter than current processing rates.

  4. Nitric Acid Dehydration Using Perfluoro Carboxylate and Mixed Sulfonate/Carboxylate Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Ames, Richard L. [Colorado School of Mines, Golden, CO (United States)

    2004-09-01

    Perfluoro ionomer membranes are tetrafluoro ethylene-based materials with microheterogeneous structures consisting of a hydrophobic polymer backbone and a hydrophilic side-chain cluster region. Due to the ionomer cluster morphology, these films exhibit unique transport properties. Recent investigations with perfluoro sulfonate and perfluoro sulfonate/carboxylate composite polymers have demonstrated their value in the dehydration of nitric acid and they show potential as an alternative to conventional, energy intensive unit operations in the concentration of acid feeds. As a result, investigations were conducted to determine the feasibility of using pure perfluoro carboxylate and mixed perfluoro sulfonate/carboxylate films for the dehydration of nitric acid because of the speculation of improved water selectivity of the carboxylate pendant chain. During the first phase of these investigations the effort was focused on generating a thin, solution cast perfluoro carboxylate ionomer film, to evaluate the general, chemical and physical characteristics of the polymer, and to assess the material's aqueous transport performance (flux and nitrate separation efficiencies) in pervaporation and high-pressure environments. Results demonstrated that generating robust solution-cast films was difficult yet a number of membranes survived high trans-membrane pressures up to 700 psig. General characterization of the solution cast product showed reduced ion exchange capacities when compared with thicker, ''as received'' perfluoro carboxylate and similar sulfonate films. Small angle x-ray scattering analysis results suggested that the solution cast carboxylate films contained a small fraction of sulfonate terminated side-chains. Aqueous transport experimentation showed that permeate fluxes for both pure water and nitric acid were approximately two orders of magnitude smaller for the carboxylate solution cast membranes when compared to their sulfonate

  5. Trans fatty acids induce vascular inflammation and reduce vascular nitric oxide production in endothelial cells.

    Directory of Open Access Journals (Sweden)

    Naomi G Iwata

    Full Text Available Intake of trans fatty acids (TFA, which are consumed by eating foods made from partially hydrogenated vegetable oils, is associated with a higher risk of cardiovascular disease. This relation can be explained by many factors including TFA's negative effect on endothelial function and reduced nitric oxide (NO bioavailability. In this study we investigated the effects of three different TFA (2 common isomers of C18 found in partially hydrogenated vegetable oil and a C18 isomer found from ruminant-derived-dairy products and meat on endothelial NF-κB activation and nitric oxide (NO production. Human endothelial cells were treated with increasing concentrations of Elaidic (trans-C18:1 (9 trans, Linoelaidic (trans-C18:2 (9 trans, 12 trans, and Transvaccenic (trans-C18:1 (11 trans for 3 h. Both Elaidic and Linoelaidic acids were associated with increasing NF-κB activation as measured by IL-6 levels and phosphorylation of IκBα, and impairment of endothelial insulin signaling and NO production, whereas Transvaccenic acid was not associated with these responses. We also measured superoxide production, which has been hypothesized to be necessary in fatty acid-dependent activation of NF-κB. Both Elaidic acid and Linoelaidic acid are associated with increased superoxide production, whereas Transvaccenic acid (which did not induce inflammatory responses did not increase superoxide production. We observed differential activation of endothelial superoxide production, NF-κB activation, and reduction in NO production by different C18 isomers suggesting that the location and number of trans double bonds effect endothelial NF-κB activation.

  6. Development of ion-exchange properties of bamboo charcoal modified with concentrated nitric acid

    Science.gov (United States)

    Khandaker, S.; Kuba, T.; Toyohara, Y.; Kamida, S.; Uchikawa, Y.

    2017-08-01

    The surface chemistry and the structural properties of activated carbon can be altered by the acidic modification. The objective of this study is to investigate the changes occurring in bamboo charcoal (BC) during activation with concentrated nitric acid. Low temperature (500°C) carbonized BC has been prepared and oxidized with 70% concentrated boiling nitric acid (BC-AC). The porous properties of the BC are analyzed with nitrogen adsorption isotherm at 77 K. The surface structure is observed by Field emission scanning electronic microscope (FESEM) and the surface functional groups are examined by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and the pH of the point of zero charge (pHPZC). The results reveal that severe oxidation with HNO3 considerably decreases the surface area of BC with enhanced pore widening and FESEM observation demonstrates the erosive effect of oxidation. The FTIR analysis detects that some absorption bands are assigned for carboxyl, aldehyde and ketone groups on BC-AC. The XPS analysis also clearly shows that the ratio of oxygen and acidic functional groups has been enriched significantly on the BC-AC. The low pHPZC value of BC-AC confirms that the surface is highly acidic for the fixation of acidic functional groups on surface. In general, the existence of the abundant amount of acidic functional groups on adsorbents enhances the sorption of heavy metals ions in aqueous solution. Therefore, it is strongly expected that the modified BC, activated under the proposed conditions would be a promising ion exchanger in aqueous solution and can be applied for the adsorption of different heavy metal ions and radioactive materials from effluent.

  7. Extraction of rare earth elements from a contaminated cropland soil using nitric acid, citric acid, and EDTA.

    Science.gov (United States)

    Tang, Hailong; Shuai, Weitao; Wang, Xiaojing; Liu, Yangsheng

    2017-08-01

    Rare earth elements (REEs) contamination to the surrounding soil has increased the concerns of health risk to the local residents. Soil washing was first attempted in our study to remediate REEs-contaminated cropland soil using nitric acid, citric acid, and ethylene diamine tetraacetic acid (EDTA) for soil decontamination and possible recovery of REEs. The extraction time, washing agent concentration, and pH value of the washing solution were optimized. The sequential extraction analysis proposed by Tessier was adopted to study the speciation changes of the REEs before and after soil washing. The extract containing citric acid was dried to obtain solid for the X-ray fluorescence (XRF) analysis. The results revealed that the optimal extraction time was 72 h, and the REEs extraction efficiency increased as the agent concentration increased from 0.01 to 0.1 mol/L. EDTA was efficient to extract REEs over a wide range of pH values, while citric acid was around pH 6.0. Under optimized conditions, the average extraction efficiencies of the major REEs in the contaminated soil were 70.96%, 64.38%, and 62.12% by EDTA, nitric acid, and citric acid, respectively. The sequential extraction analyses revealed that most soil-bounded REEs were mobilized or extracted except for those in the residual fraction. Under a comprehensive consideration of the extraction efficiency and the environmental impact, citric acid was recommended as the most suitable agent for extraction of the REEs from the contaminated cropland soils. The XRF analysis revealed that Mn, Al, Si, Pb, Fe, and REEs were the major elements in the extract indicating a possibile recovery of the REEs.

  8. Direct Synthesis of Phenol from Benzene on an Activated Carbon Catalyst Treated with Nitric Acid

    Institute of Scientific and Technical Information of China (English)

    Cui-hong Chen; Jia-quan Xu; Ming-ming Jin; Gui-ying Li; Chang-wei Hu

    2011-01-01

    Commercially available coal-based activated carbon was treated by nitric acid with different concentrations and the resultant samples were used as catalysts for the direct hydroxylation of benzene to phenol in acetonitrile. Boehm titration, X-ray photoelectron spectroscopy,scanning electron microscope coupled with an energy dispersive X-ray microanalyzer, and Brunauer-Emmett-Teller method were used to characterize toe samples. The number of carboxyl groups on the surface was found to be the main factor affecting the catalytic activity. An optimum catalytic performance with a yield of 15.7% and a selectivity of 87.2% to phenol was obtained.

  9. Formation of substrate-based gold nanocage chains through dealloying with nitric acid

    Directory of Open Access Journals (Sweden)

    Ziren Yan

    2015-06-01

    Full Text Available Metal nanocages have raised great interest because of their new properties and wide applications. Here, we report on the use of galvanic replacement reactions to synthesize substrate-supported Ag–Au nanocages from silver templates electrodeposited on transparent indium tin oxide (ITO film coated glass. The residual Ag in the composition was dealloyed with 10% nitric acid. It was found that chains of Au nanocages were formed on the substrate surface during dealloying. When the concentration of HNO3 increased to 20%, the structures of nanocages were damaged and formed crescent or semi-circular shapes. The transfer process on the substrate surface was discussed.

  10. Vertical Distribution of Ozone and Nitric Acid Vapor on the Mammoth Mountain, Eastern Sierra Nevada, California

    OpenAIRE

    2002-01-01

    In August and September 1999 and 2000, concentrations of ozone (O3) and nitric acid vapor (HNO3) were monitored at an elevation gradient (2184–3325 m) on the Mammoth Mountain, eastern Sierra Nevada, California. Passive samplers were used for monitoring exposure to tropospheric O3 and HNO3 vapor. The 2-week average O3 concentrations ranged between 45 and 72 ppb, while HNO3 concentrations ranged between 0.06 and 0.52 μg/m3. Similar ranges of O3 and HNO3 were determined for 2 years of the study....

  11. Enhanced sidewall functionalization of single-wall carbon nanotubes using nitric acid.

    Science.gov (United States)

    Tobias, Gerard; Shao, Lidong; Ballesteros, Belin; Green, Malcolm L H

    2009-10-01

    When a sample of as-made single-walled carbon nanotubes (SWNTs) is treated with nitric acid, oxidation debris are formed due to the functionalization (mainly carboxylation) of the amorphous carbon present in the sample and a continuous coating along the carbon nanotube walls is created preventing the sidewall functionalization of the SWNTs. This oxidation debris can be easily removed by an aqueous base wash leaving behind a sample with a low degree of functionality. After removal of the amorphous carbon (by steam purification) from a sample of as-made SWNTs, the resulting purified SWNTs are readily carboxylated on the walls by nitric acid treatment. The use of steam for the purification of SWNTs samples allows the removal of the amorphous carbon and graphitic layers coating the metal particles present in the sample without altering the tubular structure of the SWNTs. The exposed metal particles can then be easily removed by an acid wash. Comparison between the steam treatment and molten sodium hydroxide treatment is made.

  12. Microsystems for anion exchange separation of radionuclides in nitric acid media

    Energy Technology Data Exchange (ETDEWEB)

    Losno, M.; Brennetot, R.; Mariet, C. [DEN/Service d' Etudes Analytiques et de Reactivite des Surfaces - SEARS, CEA, Centre de Saclay, Universite Paris-Saclay, F-91191, Gif sur Yvette (France); Ferrante, I.; Descroix, S. [MMBM Group, Institut Curie Research Center, CNRS UMR 168, Paris (France)

    2016-07-01

    An efficient and reproducible photo-polymerized poly(ethylene glycol methacrylate methacrylate-co- allyl methacrylate) monolith was synthesized and a photo-grafting process based on the ene-thiol click-chemistry has been performed to give anion exchange properties to the monolith. Since their introduction in the early 1990's polymethacrylate monoliths have emerged as a powerful alternative for microscale separations or sample treatment. Their relatively simple implementation in columns with small internal diameters makes them particularly attractive for the new chromatographic challenges of complex matrices analysis and on-chip separations. Despite their relatively poor ion-exchange capacity due to their highly porous structure, their use as anion exchangers is of large interest for nuclear analysis as numerous separations are based on this process. This paper presents a systematic study of the synthesis of the polymeric porous monolith and the versatile and robust functionalization method developed for the specific strong acidic media used in radiochemical procedures. The robustness of the stationary phase was tested in concentrated nitric acid. It appears that the C-S bond formed via thiol-ene chemistry is strong enough to be used to graft function of interest for separation in strong nitric acid medium. The photo-grafted anion exchanger, a quaternary ammonium, presents sufficient resistance to be used for radionuclide separation in [HNO{sub 3}]=5 mol.L{sup -1}so the next step is its integration in the cyclo olefin copolymer (COC) micro-system.

  13. A Durable Catalyst for Vapor Phase Nitration of Benzene with Nitric Acid

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Experimental results in this work demonstrate that PW12-H2SO4/SiO2 catalyst is a good and durable catalyst for vapor phase nitration of benzene to nitrobenzene (NB) using 65% nitric acid at normal pressure. It retains the advantages of using H2SO4 as catalyst and the addition of phosphotungstic acid holds back the effusion of sulfuric acid. This new catalyst keeps high activity (the conversion of HNO3 is more than 92%), high selectivity of NB (more than 97%) and high space time yield (STY 1.5 kg NB/kg cat.h) even after 150 h on stream, under condition of 423 K, SV=3200 ml/g h.

  14. Integrated Computational and Experimental Protocol for Understanding Rh(III) Speciation in Hydrochloric and Nitric Acid Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Samuels, Alex C.; Boele, Cherilynn A.; Bennett, Kevin T.; Clark, Sue B.; Wall, Nathalie; Clark, Aurora E.

    2014-12-01

    A combined experimental and theoretical approach has investigated the complex speciation of Rh(III) in hydrochloric and nitric acid media, as a function of acid concentration. This has relevance to the separation and isolation of Rh(III) from dissolved spent nuclear fuel, which is an emergent and attractive alternative source of platinum group metals, relative to traditional mining efforts.

  15. Procedure of Destructive Chemical Recovery of Precious Metals in Nitric Acid Production

    Directory of Open Access Journals (Sweden)

    Ljubičić, M.

    2012-07-01

    Full Text Available The heart of the nitric acid production process is the chemical reactor containing a platinum-based catalyst pack and an associated catchment system, which allows the ammonia oxidation reaction to take place efficiently. Under the severe operating conditions imposed by the high-pressure ammonia oxidation process, the catalyst gauzes experience progressive deterioration, as shown by the restricted surface of the catalyst wires, the loss of catalytic activity and the loss of catalytic materials. The higher the pressure of gaseous ammonia oxidation, the greater the loss of platinum group metals from the surface of the applied selective heterogeneous catalysts. Total losses for one batch over the whole period of using selective heterogeneous catalysts may account in the range from 20 to 40 % of the total installed quantity of precious metals. An important part of the platinum removed from the platinum-rhodium alloy wires can be recovered at the outlet of the reactor by means of palladium catchment gauzes. However, this catchment process, which is based on the great ability of palladium to alloy with platinum, is not 100 % effective and a fraction of the platinum and practically all of the rhodium lost by the catalyst wires, evades the catchment package and is then deposited in other parts of the plant, especially heat exchangers. From the above mentioned operating equipment, the retained mass of precious metals can be recovered by the technical procedure of non-destructive and destructive chemical solid-liquid extraction.Shown is the technical procedure of destructive chemical recovery of preheater and boiler for preheating and production of steam by applying sulfuric acid (w = 20 % and subsequent procedure of raffination of derived sludge, to the final recovery of precious metals. The technical procedure of destructive chemical recovery of precious metals from preheater and boiler for preheating and production of steam in nitric acid production is

  16. Single-cycle method for partitioning of trivalent actinides using completely incinerable reagents from nitric acid medium

    Energy Technology Data Exchange (ETDEWEB)

    Ravi, Jammu; Venkatesan, K.A.; Antony, M.P.; Srinivasan, T.G.; Rao, P.R. Vasudeva [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Fuel Chemistry Div.

    2014-10-01

    A new approach, namely 'Single-cycle method for partitioning of Minor Actinides using completely incinerable ReagenTs' (SMART), has been explored for the separation of Am(III) from Eu(III) present in nitric acid medium. The extraction behavior of Am(III) and Eu(III) in a solution of an unsymmetrical diglycolamide, N,N,-didodecyl-N',N'-dioctyl-3-oxapentane-1,5-diamide (D{sup 3}DODGA), and an acidic extractant, N,N-di-2-ethylhexyl diglycolamic acid (HDEHDGA), in n-dodecane was studied. The distribution ratio of both these metal ions in D{sup 3}DODGA-HDEHDGA/n-dodecane initially decreased with increase in the concentration of nitric acid reached a minimum at 0.1 M nitric acid followed by increase. Synergic extraction of Am(III) and Eu(III) was observed at nitric acid concentrations above 0.1 M and antagonism at lower acidities. Contrasting behavior observed at different acidities was probed by the slope analysis of the extraction data. The study revealed the involvement of both D{sup 3}DODGA and HDEHDGA during synergism and increased participation of HDEHDGA during antagonism. The stripping behavior of Am(III) and Eu(III) from the loaded organic phase was studied as a function of nitric acid, DTPA, and citric acid concentrations. The conditions needed for the mutual separation of Am(III) and Eu(III) from the loaded organic phase were optimized. Our studies revealed the possibility of separating trivalent actinides from HLLW using these completely incinerable reagents. (orig.)

  17. Homogeneous nucleation rates of nitric acid dihydrate (NAD at simulated stratospheric conditions – Part II: Modelling

    Directory of Open Access Journals (Sweden)

    O. Möhler

    2006-01-01

    Full Text Available Activation energies ΔGact for the nucleation of nitric acid dihydrate (NAD in supercooled binary HNO3/H2O solution droplets were calculated from volume-based nucleation rate measurements using the AIDA (Aerosol, Interactions, and Dynamics in the Atmosphere aerosol chamber of Forschungszentrum Karlsruhe. The experimental conditions covered temperatures T between 192 and 197 K, NAD saturation ratios SNAD between 7 and 10, and nitric acid molar fractions of the nucleating sub-micron sized droplets between 0.26 and 0.28. Based on classical nucleation theory, a new parameterisation for ΔGact=A×(T ln SNAD−2+B is fitted to the experimental data with A=2.5×106 kcal K2 mol−1 and B=11.2−0.1(T−192 kcal mol−1. A and B were chosen to also achieve good agreement with literature data of ΔGact. The parameter A implies, for the temperature and composition range of our analysis, a mean interface tension σsl=51 cal mol−1 cm−2 between the growing NAD germ and the supercooled solution. A slight temperature dependence of the diffusion activation energy is represented by the parameter B. Investigations with a detailed microphysical process model showed that literature formulations of volume-based (Salcedo et al., 2001 and surface-based (Tabazadeh et al., 2002 nucleation rates significantly overestimate NAD formation rates when applied to the conditions of our experiments.

  18. Decontamination of uranium-contaminated waste oil using supercritical fluid and nitric acid.

    Science.gov (United States)

    Sung, Jinhyun; Kim, Jungsoo; Lee, Youngbae; Seol, Jeunggun; Ryu, Jaebong; Park, Kwangheon

    2011-07-01

    The waste oil used in nuclear fuel processing is contaminated with uranium because of its contact with materials or environments containing uranium. Under current law, waste oil that has been contaminated with uranium is very difficult to dispose of at a radioactive waste disposal site. To dispose of the uranium-contaminated waste oil, the uranium was separated from the contaminated waste oil. Supercritical R-22 is an excellent solvent for extracting clean oil from uranium-contaminated waste oil. The critical temperature of R-22 is 96.15 °C and the critical pressure is 49.9 bar. In this study, a process to remove uranium from the uranium-contaminated waste oil using supercritical R-22 was developed. The waste oil has a small amount of additives containing N, S or P, such as amines, dithiocarbamates and dialkyldithiophosphates. It seems that these organic additives form uranium-combined compounds. For this reason, dissolution of uranium from the uranium-combined compounds using nitric acid was needed. The efficiency of the removal of uranium from the uranium-contaminated waste oil using supercritical R-22 extraction and nitric acid treatment was determined.

  19. Temperature effects on the nitric acid oxidation of industrial grade multiwalled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Nadia F., E-mail: nadia@fisica.ufc.br [Universidade Federal do Ceara, Departamento de Fisica (Brazil); Martinez, Diego Stefani T., E-mail: diegostefani.br@gmail.com; Paula, Amauri J., E-mail: amaurijp@gmail.com [Universidade Estadual de Campinas (UNICAMP), Laboratorio de Quimica do Estado Solido (LQES), Instituto de Quimica (Brazil); Silveira, Jose V. [Universidade Federal do Ceara, Departamento de Fisica (Brazil); Alves, Oswaldo L., E-mail: oalves@iqm.unicamp.br [Universidade Estadual de Campinas (UNICAMP), Laboratorio de Quimica do Estado Solido (LQES), Instituto de Quimica (Brazil); Souza Filho, Antonio G., E-mail: agsf@fisica.ufc.br [Universidade Federal do Ceara, Departamento de Fisica (Brazil)

    2013-07-15

    In this study, we report an oxidative treatment of multiwalled carbon nanotubes (MWCNTs) by using nitric acid at different temperatures (25-175 Degree-Sign C). The analyzed materials have diameters varying from 10 to 40 nm and majority lengths between 3 and 6 {mu}m. The characterization results obtained by different techniques (e.g., field emission scanning electron microscopy, thermogravimetric analysis, energy-filtered transmission electron microscopy, Braunauer, Emmet and Teller method, {zeta}-potential and confocal Raman spectroscopy) allowed us to access the effects of temperature treatment on the relevant physico-chemical properties of the MWCNTs samples studied in view of an integrated perspective to use these samples in a bio-toxicological context. Analytical microbalance measurements were used to access the purity of samples (metallic residue) after thermogravimetric analysis. Confocal Raman spectroscopy measurements were used to evaluate the density of structural defects created on the surface of the tubes due to the oxidation process by using 2D Raman image. Finally, we have demonstrated that temperature is an important parameter in the generation of oxidation debris (a byproduct which has not been properly taken into account in the literature) in the industrial grade MWCNTs studied after nitric acid purification and functionalization.

  20. Electrochemical oxidation of 243Am(III) in nitric acid by a terpyridyl-derivatized electrode

    Energy Technology Data Exchange (ETDEWEB)

    Dares, C. J.; Lapides, A. M.; Mincher, B. J.; Meyer, T. J.

    2015-11-05

    A high surface area, tin-doped indium oxide electrode surface-derivatized with a terpyridine ligand has been applied to the oxidation of trivalent americium to Am(V) and Am(VI) in nitric acid. Potentials as low as 1.8 V vs. the saturated calomel electrode are used, 0.7 V lower than the 2.6 V potential for one-electron oxidation of Am(III) to Am(IV) in 1 M acid. This simple electrochemical procedure provides, for the first time, a method for accessing the higher oxidation states of Am in non-complexing media for developing the coordination chemistries of Am(V) and Am(VI) and, more importantly, for separation of americium from nuclear waste streams.

  1. 42 CFR 84.1146 - Lead fume test for dust, fume, and mist respirators; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Lead fume test for dust, fume, and mist respirators... Efficiency Respirators and Combination Gas Masks § 84.1146 Lead fume test for dust, fume, and mist respirators; minimum requirements. (a) Three non-powered respirators will be tested for a period of...

  2. Nitric oxide metabolism and indole acetic acid biosynthesis cross-talk in Azospirillum brasilense SM.

    Science.gov (United States)

    Koul, Vatsala; Tripathi, Chandrakant; Adholeya, Alok; Kochar, Mandira

    2015-04-01

    Production of nitric oxide (NO) and the presence of NO metabolism genes, nitrous oxide reductase (nosZ), nitrous oxide reductase regulator (nosR) and nitric oxide reductase (norB) were identified in the plant-associated bacterium (PAB) Azospirillum brasilense SM. NO presence was confirmed in all overexpressing strains, while improvement in the plant growth response of these strains was mediated by increased NO and indole-3-acetic acid (IAA) levels in the strains. Electron microscopy showed random distribution to biofilm, with surface colonization of pleiomorphic Azospirilla. Quantitative IAA estimation highlighted a crucial role of nosR and norBC in regulating IAA biosynthesis. The NO quencher and donor reduced/blocked IAA biosynthesis by all strains, indicating their common regulatory role in IAA biosynthesis. Tryptophan (Trp) and l-Arginine (Arg) showed higher expression of NO genes tested, while in the case of ipdC, only Trp and IAA increased expression, while Arg had no significant effect. The highest nosR expression in SMnosR in the presence of IAA and Trp, along with its 2-fold IAA level, confirmed the relationship of nosR overexpression with Trp in increasing IAA. These results indicate a strong correlation between IAA and NO in A. brasilense SM and suggest the existence of cross-talk or shared signaling mechanisms in these two growth regulators.

  3. Occupational rhinitis due to steel welding fumes.

    Science.gov (United States)

    Castano, Roberto; Suarthana, Eva

    2014-12-01

    Exposure to welding fumes is a recognized respiratory hazard. Occupational asthma but not occupational rhinitis has been documented in workers exposed to steel welding fumes. We report a 26-year-old male with work-related rhinitis symptoms as well as lower airways symptoms suggestive of occupational asthma and metal fume fever associated with exposure to steel welding fumes. The diagnosis of occupational rhinitis was confirmed by specific inhalation challenge.

  4. Studies of dissolution solutions of ruthenium metal, oxide and mixed compounds in nitric acid

    Energy Technology Data Exchange (ETDEWEB)

    Mousset, F.; Eysseric, C.; Bedioui, F

    2004-07-01

    Ruthenium is one of the fission products generated by irradiated nuclear fuel. It is present throughout all the steps of nuclear fuel reprocessing-particularly during extraction-and requires special attention due to its complex chemistry and high {beta}{gamma} activity. An innovative electro-volatilization process is now being developed to take advantage of the volatility of RuO{sub 4} in order to eliminate it at the head end of the Purex process and thus reduce the number of extraction cycles. Although the process operates successfully with synthetic nitrato-RuNO{sup 3+} solutions, difficulties have been encountered in extrapolating it to real-like dissolution solutions. In order to better approximate the chemical forms of ruthenium found in fuel dissolution solutions, kinetic and speciation studies on dissolved species were undertaken with RuO{sub 2},xH{sub 2}O and Ru{sup 0} in nitric acid media. (authors)

  5. Extraction of uranium (VI) from nitric acid solutions with N,N,-di-n-butyloctanamide

    Energy Technology Data Exchange (ETDEWEB)

    Dembinski, W.; Gasparini, G.M.

    1980-12-01

    N,N-dialkylamides show interesting properties as new extracting agents of actinides. This report presents the data concerning the N,N-di-n-butyloctanamide: CH/sub 3/-(CH/sub 2/)/sub 5/-CH/sub 2/-C(O)N (C/sub 4/H/sub 9/)/sub 2/. In particular the following have been studied: the formation of a third phase with n-dodecane and mesitylene as diluents; the influence of the concentration of the uranium of the nitric acid and of the extractant on the distribution coeffcient, of uranium(VI); the radiation stability of this amide and the influence of the absorbed dose on the distribution coefficient for U(VI). The general properties of the di-n-butyloctanamide as potential extractant of uranium are discussed.

  6. Study on Purification Diatomite with nitric acid by Thermal Closed System

    Directory of Open Access Journals (Sweden)

    Kuang Meng

    2016-01-01

    Full Text Available In this research, a purification approach using nitric acid leaching at thermal closed system was developed to improve the porous structure of raw diatomite by removal of impurities from its surface and clogged pores. The feasibility and efficiency of this approach were determined by XRF for chemical constitution of diatomite, SEM for morphology and BET for specific surface area of purified diatomite. The investigations indicated that the content of SiO2 was in order of 85.14% for raw diatomite and 98% for purified diatomite, the content of Fe2O3 decreases after purified; the integrity of the porous structure was confirmed by SEM, and increase in specific surface area from 18m2·g-1 to 36m2·g-1.

  7. Spatial and temporal distribution of ambient nitric acid and ammonia in the Athabasca Oil Sands Region, Alberta

    Science.gov (United States)

    A. Bytnerowicz; W. Fraczek; S. Schilling; D. Alexander

    2010-01-01

    Monthly average ambient concentrations of gaseous nitric acid (HNO3) and ammonia (NH3) were monitored at the Athabasca Oils Sands Region (AOSR), Alberta, Canada, between May 2005 and September 2008. Generally, concentrations of both pollutants were elevated and highly variable in space and time. The highest atmospheric...

  8. N,N,N‘,N’—tetrabutylmalonamide as a new extractant for extraction of nitric acid and uranium(VI)

    Institute of Scientific and Technical Information of China (English)

    WangYou-Shao; SunXiao-Yu; 等

    1997-01-01

    N,N,N',N'-tetrabutylmalonamide(TBMA) is synthesized and used for extraction of uranyl(Ⅱ) ion from nitric acid media in a diluent composed of 50% 1,2,4-trimethyl benzene (TMB) and 50% kerosene(OK),The effects of nitric acid concentration,extractant concentration,temperature,slating-out agent (LiNO3) and back extraction on distribution coefficients of uranyl(Ⅱ) ion have been studied.The extraction of nitric acid is also studied.The main adduct of TBMA and HNO3 is HNO3.TBMA,and there are more than two kinds of adducts in 3.0mol/L nitric acid solutions,such as HNO3.TBMA,(HNO3)2,TBMA and (NHO3)3.TBMA.The complex formation of uranyl(Ⅱ) ion,nitrate ion and TBMA(1:2:1) as extracted species is further confirmed by IR spectra of the saturated extraction of uranyl(Ⅱ) ion with TBMA,and the values of thermodynamic parameters have also been calculated.

  9. Evaluation of the Single Dilute (0.43 M) Nitric Acid Extraction to Determine Geochemically Reactive Elements in Soil

    NARCIS (Netherlands)

    Groenenberg, Jan E.; Römkens, Paul F.A.M.; Zomeren, van André; Rodrigues, S.M.; Comans, Rob N.J.

    2017-01-01

    Recently a dilute nitric acid extraction (0.43 M) was adopted by ISO (ISO-17586:2016) as standard for extraction of geochemically reactive elements in soil and soil like materials. Here we evaluate the performance of this extraction for a wide range of elements by mechanistic geochemical modeling

  10. Nitrous-Oxide Flux from Nitric-Acid-Treated Cattle Slurry Applied to Grassland under Semi-Controlled Conditions

    NARCIS (Netherlands)

    Velthof, G.L.; Oenema, O.

    1993-01-01

    Nitrous oxide (N2O) fluxes from cattle slurry after surface application to grassland were measured under semi-controlled environmental conditions during three periods in 1991. Three types of cattle slurry were examined; untreated slurry and slurries treated with nitric acid (HNO3) to pH 6.0 and 4.5.

  11. Nitric Acid Deposition following an Astrophysical Ionizing Radiation Event is below Critical Loads for Terrestrial and Freshwater Ecosystems

    CERN Document Server

    Melott, Ben Neuenswander Adrian

    2014-01-01

    Nitric acid rainout is one of the effects of an astrophysical ionizing radiation event. The predicted values of nitrate rainout from previous work for a typical gamma ray burst (GRB) within our galaxy serve as an extreme example and are shown to be below critical loads of eutrophication and acidification for ecoregions in Europe and the US.

  12. Ammonium nitrate evaporation and nitric acid condensation in DMT CCN counters

    Science.gov (United States)

    Romakkaniemi, S.; Jaatinen, A.; Laaksonen, A.; Nenes, A.; Raatikainen, T.

    2014-05-01

    The effect of inorganic semivolatile aerosol compounds on the cloud condensation nucleus (CCN) activity of aerosol particles was studied by using a computational model for a DMT-CCN counter, a cloud parcel model for condensation kinetics and experiments to quantify the modelled results. Concentrations of water vapour and semivolatiles as well as aerosol trajectories in the CCN column were calculated by a computational fluid dynamics model. These trajectories and vapour concentrations were then used as an input for the cloud parcel model to simulate mass transfer kinetics of water and semivolatiles between aerosol particles and the gas phase. Two different questions were studied: (1) how big a fraction of semivolatiles is evaporated from particles after entering but before particle activation in the DMT-CCN counter? (2) How much can the CCN activity be increased due to condensation of semivolatiles prior to the maximum water supersaturation in the case of high semivolatile concentration in the gas phase? Both experimental and modelling results show that the evaporation of ammonia and nitric acid from ammonium nitrate particles causes a 10 to 15 nm decrease to the critical particle size in supersaturations between 0.1% and 0.7%. On the other hand, the modelling results also show that condensation of nitric acid or similar vapour can increase the CCN activity of nonvolatile aerosol particles, but a very high gas phase concentration (as compared to typical ambient conditions) would be needed. Overall, it is more likely that the CCN activity of semivolatile aerosol is underestimated than overestimated in the measurements conducted in ambient conditions.

  13. Effect of humidity on nitric acid uptake to mineral dust aerosol particles

    Directory of Open Access Journals (Sweden)

    A. Vlasenko

    2006-01-01

    Full Text Available This study presents the first laboratory observation of HNO3 uptake by airborne mineral dust particles. The model aerosols were generated by dry dispersion of Arizona Test Dust (ATD, SiO2, and by nebulizing a saturated solution of calcium carbonate. The uptake of 13N-labeled gaseous nitric acid was observed in a flow reactor on the 0.2–2 s reaction time scale at room temperature and atmospheric pressure. The amount of nitric acid appearing in the aerosol phase at the end of the flow tube was found to be a linear function of the aerosol surface area. SiO2 particles did not show any significant uptake, while the CaCO3 aerosol was found to be more reactive than ATD. Due to the smaller uncertainty associated with the reactive surface area in the case of suspended particles as compared to bulk powder samples, we believe that we provide an improved estimate of the rate of uptake of HNO3 to mineral dust. The fact that the rate of uptake was smaller at a concentration of 1012 than at 1011 was indicative of a complex uptake mechanism. The uptake coefficient averaged over the first 2 s of reaction time at a concentration of 1012 molecules cm-3 was found to increase with increasing relative humidity, from 0.022±0.007 at 12% RH to 0.113±0.017 at 73% RH , which was attributed to an increasing degree of solvation of the more basic minerals. The extended processing of the dust by higher concentrations of HNO3 at 85% RH led to a water soluble coating on the particles and enhanced their hygroscopicity.

  14. Investigation on surface structure of potassium permanganate/nitric acid treated poly(tetrafluoroethylene)

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Congli; Liu, Shuling; Gong, Tianlong; Gu, Aiqun; Yu, Zili, E-mail: ziliyu@scu.edu.cn

    2014-10-30

    Highlights: • A new transformation (conversion) mechanism of PTFE surface from a hydrophobicity to a hydrophilicity was proposed through the treatment of KMnO{sub 4}/HNO{sub 3}. • Chemical reactions or defluorination of PTFE described in the reported paper was testified to be a misconceived conclusion by the combination of several testing measurements (IR, XPS, XRD and so on) in our present work. • Deposition of manganese oxide and/or manganese hydroxide on PTFE surface contributed to the hydrophilic property of the modified PTFE with KMnO{sub 4}/HNO{sub 3} treated. • The deposition thickness on the modified PTFE surface was about 5 μm, which was significantly helpful in enhancing the adhesive strength of PTFE with other materials. - Abstract: In the previous articles concerning the treatment of poly(tetrafluoroethylene) (PTFE) with potassium permanganate/nitric acid mixture, the conversion of a hydrophobic to a hydrophilic surface was partially assigned to the defluorination of PTFE and then the introduction of carbonyl and hydroxyl groups into the defluorinated sites. In the present work, PTFE sheets were treated with potassium permanganate/nitric acid, and the surfaces before and after treatment were comparatively characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The surface sediments of the treated PTFE were also determined by atomic absorption spectroscopy (AAS). The results indicate that the conversion of the hydrophobicity to the hydrophilicity on the modified PTFE surface is mainly due to the deposition of hydrophilic manganese oxides which covered the fluorocarbon surface, and no detectable chemical reactions of PTFE occur in the treating process.

  15. Optimization of the nitrous vapors experimental conditions production by nitric acid electrochemical reduction; Optimisation des conditions operatoires de production de vapeurs nitreuses par reduction electrochimique d`acide nitrique

    Energy Technology Data Exchange (ETDEWEB)

    Lemaire, M.

    1996-11-22

    Gaseous nitrogen oxides (NO and NO{sub 2}) involved as oxidizing agents in nuclear fuel reprocessing can be produced by electrochemical reduction of nitric acid. This is an interesting alternative to the existing process because no wastes are generated. voltammetric studies on a platinum electrode show that two reduction potential regions are observed in concentrated nitric acid solutions, between 0,05 V{sub SHE} and between 0,5 V{sub SHE} and 1 V{sub SHE}. The highest potential region reduction mechanism was studied by: classical micro-electrolysis methods, macro-electrolysis methods, infrared spectroscopy coupled to electrochemistry. It was determined that the origin of nitric acid reduction is the electrochemical reduction of nitrous acid in nitric oxide which chemically reduces nitric acid. This reaction produces nitrous acid back which indicate an auto-catalytic behaviour of nitric acid reduction mechanism. Nitrogen dioxide evolution during nitric reduction can also explained by an other chemical reaction. If the potential value of platinum electrode is above 0,8 V{sub SHE}, products of the indirect nitric acid reduction are nitrous acid, nitrogen oxide and nitrogen dioxide. Below this value nitric oxide can be reduced in nitrous oxide. Thus the potential value is the most important parameter for the nitrogen oxides production selectivity. However, owing to the auto-catalytic character of the reduction mechanism, potential value can be controlled during intentiostatic industrial electrolysis. (author). 91 refs.

  16. N,N-dialkyl-2-hydroxyacetamides for modifier-free separation of trivalent actinides from nitric acid medium

    Energy Technology Data Exchange (ETDEWEB)

    Prathibha, T.; Kumaresan, R.; Selvan, B. Robert; Venkatesan, K.A.; Antony, M.P.; Vasudeva Rao, P.R. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Fuel Chemistry Div.

    2016-07-01

    The alkyl derivatives of N,N,-dialkyl-2-hydroxyacetamide (DAHyA), namely, N,N,-dihexyl-2-hydroxyacetamide (DHHyA), N,N,-dioctyl-2-hydroxyacetamide (DOHyA), N,N,-didecyl-2-hydroxyacetamide (DDHyA), were synthesized and characterized by FT-IR, and NMR spectroscopy. The extraction behaviour of Am(III) in a solution of DAHyA in n-dodecane was studied as a function of various parameters to evaluate the feasibility of using DAHyA for partitioning of trivalent actinides from high-level liquid waste (HLLW). The distribution ratio of Am(III) (D{sub Am(III)}) in 0.1 M DAHyA/n-DD increased from 10{sup -4} to > 200 with increase in nitric acid concentration from 1 M to 6 M. A D{sub Am(III)} value 10-70 was obtained in a nitric acid concentration range from 3-4 M. The extraction of Am(III) in 0.1 M DAHyA/n-dodecane decreased in the order DHHyA > DOHyA > DDHyA. The third-phase formation behaviour of nitric acid and neodymium (III) in 0.2 M DAHyA/n-dodecane was studied. Near stoichiometric amount of neodymium (III) can be loaded in octyl and decyl derivatives without any third-phase formation from 3-4 M nitric acid medium. Unlike other extractants, the loaded trivalent metal ion in DAHyA can be recovered even with 1 M nitric acid. Therefore, the study revealed that N,N,-dialkyl-2-hydroxyacetamides are promising candidates for partitioning the trivalent actinides from HLLW.

  17. Study of Removal Nitrous Acid From Nitric Acid Solution Using Packed Column

    Institute of Scientific and Technical Information of China (English)

    LAN; Tian; CHANG; Shang-wen; LIU; Jin-ping; ZHOU; Xian-ming; LI; Gao-liang; TANG; Hong-bin; HE; Hui

    2013-01-01

    It is necessary that the adjustment of the Pu(Ⅲ)to Pu(Ⅳ)should be used excess nitride gases befor the cycle of Pu purification in Purex.The mass of nitrous acid were present in solution after adjustment.Ifthe solution contain the mass of nitrous acid arrived at the cycle of Pupurification,the nitrous could react with Pu reducing agent in the processof Pu back-extractionbecause nitrous acid could extracted to organic,

  18. Validation Testing of the Nitric Acid Dissolution Step Within the K Basin Sludge Pretreatment Process

    Energy Technology Data Exchange (ETDEWEB)

    AJ Schmidt; CH Delegard; KL Silvers; PR Bredt; CD Carlson; EW Hoppe; JC Hayes; DE Rinehart; SR Gano; BM Thornton

    1999-03-24

    The work described in this report involved comprehensive bench-scale testing of nitric acid (HNO{sub 3}) dissolution of actual sludge materials from the Hanford K East (KE) Basin to confirm the baseline chemical pretreatment process. In addition, process monitoring and material balance information was collected to support the development and refinement of process flow diagrams. The testing was performed by Pacific Northwest National Laboratory (PNNL)for the US Department of Energy's Office of Spent Fuel Stabilization (EM-67) and Numatec Hanford Corporation (NHC) to assist in the development of the K Basin Sludge Pretreatment Process. The baseline chemical pretreatment process for K Basin sludge is nitric acid dissolution of all particulate material passing a 1/4-in. screen. The acid-insoluble fraction (residual solids) will be stabilized (possibly by chemical leaching/rinsing and grouting), packaged, and transferred to the Hanford Environmental Restoration Disposal Facility (ERDF). The liquid fraction is to be diluted with depleted uranium for uranium criticality safety and iron nitrate for plutonium criticality safety, and neutralized with sodium hydroxide. The liquid fraction and associated precipitates are to be stored in the Hanford Tank Waste Remediation Systems (TWRS) pending vitrification. It is expected that most of the polychlorinated biphenyls (PCBs), associated with some K Basin sludges, will remain with the residual solids for ultimate disposal to ERDF. Filtration and precipitation during the neutralization step will further remove trace quantities of PCBs within the liquid fraction. The purpose of the work discussed in this report was to examine the dissolution behavior of actual KE Basin sludge materials at baseline flowsheet conditions and validate the.dissolution process step through bench-scale testing. The progress of the dissolution was evaluated by measuring the solution electrical conductivity and concentrations of key species in the

  19. Freezing of sulfuric and nitric acid solutions: Implications for polar stratospheric cloud formation

    Science.gov (United States)

    Salcedo Gonzalez, Dara

    2000-12-01

    Polar Stratospheric Clouds (PSCs) play an important role in ozone chemistry during the polar winter. The magnitude of their effect depends on their phase, composition and formation mechanism, which are not fully understood yet. In order to understand how liquid PSCs freeze, two apparatus were designed to study the freezing behavior of small drops using a Fourier transform infrared (FTIR) spectrometer and an optical microscope. Sulfuric acid aqueous drops with composition of 10 to 50 wt % were studied with the FTIR apparatus. The surface on which the drops stand caused heterogeneous nucleation of ice, but not of the sulfuric acid hydrates. The more concentrated solutions (>40 wt %) supercooled to 130 K without freezing. Below 150 K these solutions formed an amorphous solid, which liquefied upon warming. Drops with composition of 40 to 64 wt % HNO3 were prepared and their phase transitions were detected with the optical microscope apparatus. Freezing temperatures of the drops were determined and homogeneous nucleation rates of nitric acid dihydrate (JNAD) and nitric acid trihydrate (JNAT) between 170 and 190 K were calculated. JNAT and JNAD depend predominantly on the saturation of the solid in the liquid solution: higher saturation ratios correspond to higher nucleation rates. Classical nucleation theory was used to parameterize this relation. Since the saturation ratios of NAD and NAT vary with temperature and composition in different ways, NAT or NAD can form preferentially under different conditions. Evidence was found that NAD catalyzes the nucleation of NAT below ~183 K. Mullite, cristobalite and alumina were tested as possible heterogeneous nuclei of volcanic origin for PSCs. They catalyze freezing of NAD and NAT at temperatures below 179 K, which are too low to be stratospherically important. The results suggest that the largest drops in a PSC will freeze homogeneously if the stratospheric temperature remains below the NAT condensation temperature for more

  20. The Pozzolanic reaction of silica fume

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede

    2012-01-01

    Silica fume is a very important supplementary cementitious binder in High-Performance and Ultra High-Performance Concretes. Through its pozzolanic reaction the silica fume densifies the concrete micro-structure, in particular it strengthens the paste-aggregate interfacial transition zone. In the ...... of activation of the pozzolanic reaction of silica fume is estimated. The results show that the pozzolanic reaction of silica fume has notable differences from Portland cement hydration.......Silica fume is a very important supplementary cementitious binder in High-Performance and Ultra High-Performance Concretes. Through its pozzolanic reaction the silica fume densifies the concrete micro-structure, in particular it strengthens the paste-aggregate interfacial transition zone....... In the present paper different aspects of the pozzolanic reaction of silica fume are investigated. These include chemical shrinkage, isothermal heat development and strength development. Key data for these are given and compared with theoretical calculations, and based on presented measurements the energy...

  1. Determination of Nitric Acid in Aqueous Solution of Uranium and Plutonium Purification Cycle by Near Infrared Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    LI; Ding-ming; WANG; Lin; ZHANG; Li-hua; GONG; Yan-ping; MU; Ling; WU; Ji-zong

    2012-01-01

    <正>The concentration of nitric acid interfered with the distribution of uranium and plutonium in nuclear fuel reprocessing process. So, in the reprocessing process control analysis, the determination of the free acid plays an important role. Traditional laboratory analytical method of free acid needs large size sample and is time-consuming. Hence, development of fast analytical method for free acid has important significance for the reprocessing process control analysis. Near-infrared spectroscopy (NIRS) has been proved to be a powerful analytical tool and used in various fields, it’s seldom, however, used in spent

  2. Water-soluble nitric-oxide-releasing acetylsalicylic acid (ASA) prodrugs.

    Science.gov (United States)

    Rolando, Barbara; Lazzarato, Loretta; Donnola, Monica; Marini, Elisabetta; Joseph, Sony; Morini, Giuseppina; Pozzoli, Cristina; Fruttero, Roberta; Gasco, Alberto

    2013-07-01

    A series of water-soluble (benzoyloxy)methyl esters of acetylsalicylic acid (ASA), commonly known as aspirin, are described. The new derivatives each have alkyl chains containing a nitric oxide (NO)-releasing nitrooxy group and a solubilizing moiety bonded to the benzoyl ring. The compounds were synthesized and evaluated as ASA prodrugs. After conversion to the appropriate salt, most of the derivatives are solid at room temperature and all possess good water solubility. They are quite stable in acid solution (pH 1) and less stable at physiological pH. In human serum, these compounds are immediately metabolized by esterases, producing a mixture of ASA, salicylic acid (SA), and of the related NO-donor benzoic acids, along with other minor products. Due to ASA release, the prodrugs are capable of inhibiting collagen-induced platelet aggregation of human platelet-rich plasma. Simple NO-donor benzoic acids 3-hydroxy-4-(3-nitrooxypropoxy)benzoic acid (28) and 3-(morpholin-4-ylmethyl)-4-[3-(nitrooxy)propoxy]benzoic acid (48) were also studied as representative models of the whole class of benzoic acids formed following metabolism of the prodrugs in serum. These simplified derivatives did not trigger antiaggregatory activity when tested at 300 μM. Only 28 displays quite potent NO-dependent vasodilatatory action. Further in vivo evaluation of two selected prodrugs, {[2-(acetyloxy)benzoyl]oxy}methyl-3-[(3-[aminopropanoyl)oxy]-4-[3-(nitrooxy)propoxy]benzoate⋅HCl (38) and {[2-(acetyloxy)benzoyl]oxy}methyl 3-(morpholin-4-ylmethyl)-4-[3-(nitrooxy)propoxy]benzoate oxalate (49), revealed that their anti-inflammatory activities are similar to that of ASA when tested in the carrageenan-induced paw edema assay in rats. The gastrotoxicity of the two prodrugs was also determined to be lower than that of ASA in a lesion model in rats. Taken together, these results indicated that these NO-donor ASA prodrugs warrant further investigation for clinical application.

  3. A quantitative test of infrared optical constants for supercooled sulphuric and nitric acid droplet aerosols

    Directory of Open Access Journals (Sweden)

    R. Wagner

    2003-05-01

    Full Text Available In situ Fourier transform infrared (FTIR extinction spectra of supercooled H2SO4/H2O and HNO3/H2O solution droplets were recorded in the large coolable aerosol chamber AIDA (Aerosol Interactions and Dynamics in the Atmosphere of Forschungszentrum Karlsruhe for a range of aerosol compositions and at temperatures extending down to 192 K. The measured spectra were quantitatively analysed in terms of aerosol composition and mass concentration by using Mie theory in combination with published refractive index data as input parameters. Simultaneously, total sulphuric acid and nitric acid mass concentrations from filter analysis and total water concentrations measured with the Lyman-a hygrometer of Forschungszentrum Jülich were used to calculate the aerosol composition at thermodynamic equilibrium inside the aerosol chamber. By comparing these measured aerosol parameters with those retrieved from the analysis of the FTIR spectra, the accuracy of the literature data sets of refractive indices could be assessed. In summary, four data sets were tested in the H2SO4/H2O system as well as two data sets in the HNO3/H2O system, partly revealing significant discrepancies in the retrieved aerosol properties. Potential explanations for these differences are discussed in this paper.

  4. Hyaluronic acid abrogates nitric oxide-dependent stimulation of collagen degradation in cultured human chondrocytes.

    Science.gov (United States)

    Surazynski, Arkadiusz; Miltyk, Wojciech; Czarnomysy, Robert; Grabowska, Joanna; Palka, Jerzy

    2009-07-01

    Experimental inflammation induced in cultured chondrocytes by inflammatory cytokine IL-1 beta stimulates collagen degradation by metalloproteinases. We propose that nitric oxide (NO) may represent down stream signaling molecule of IL-1-induced collagen degradation in chondrocytes. It was found that IL-1 beta induced the activity of MMP-2 and MMP-9 during the 48 h time course of the experiment, especially after 24h incubation, while DETA/NO, donor of NO, stimulated the process at 12h incubation. The mechanism of IL-1-dependent stimulation of NO production was found at the level of iNOS expression and activation of NF-kappaB. We found that hyaluronic acid (HA) counteracted IL-induced degradation of collagen in chondrocytes. Although, HA by itself had no effect on the metaloproteinases activity, when added to IL-1 beta or DETA/NO treated chondrocytes it contributed to the restoration of the MMPs activity to the control level. The mechanism of this phenomenon involves inhibition of NF-kappaB activation. The data suggest that NO may represent a target molecule for protective effect of hyaluronic acid on interleukin-1-induced stimulation of metaloproteinases activity in cultured human chondrocytes.

  5. A safer and flexible method for the oxygen functionalization of carbon nanotubes by nitric acid vapors

    Energy Technology Data Exchange (ETDEWEB)

    Santangelo, Saveria, E-mail: saveria.santangelo@unirc.it [Dipartimento di Ingegneria Civile, dell’Energia, dell’Ambiente e dei Materiali (DICEAM), Università “Mediterranea”, 89122 Reggio Calabria (Italy); Piperopoulos, Elpida [Dipartimento di Ingegneria Eletronica, Chimica ed Ingegneria Industriale (DIECII), Università di Messina, 98166 Messina (Italy); Fazio, Enza [Dipartimento di Fisica e di Scienze della Terra (DFST), Università di Messina, 98166 Messina (Italy); Faggio, Giuliana [Dipartimento di Ingegneria dell’Informazione, delle Infrastrutture e dell’Energia Sostenibile (DIIES), Università “Mediterranea”, 89122 Reggio Calabria (Italy); Ansari, Shabana [Dipartimento di Ingegneria Eletronica, Chimica ed Ingegneria Industriale (DIECII), Università di Messina, 98166 Messina (Italy); Lanza, Maurizio [Istituto per i Processi Chimico Fisici (IPCF) del CNR, 98158 Messina (Italy); Neri, Fortunato [Dipartimento di Fisica e di Scienze della Terra (DFST), Università di Messina, 98166 Messina (Italy); Messina, Giacomo [Dipartimento di Ingegneria dell’Informazione, delle Infrastrutture e dell’Energia Sostenibile (DIIES), Università “Mediterranea”, 89122 Reggio Calabria (Italy); Milone, Candida [Dipartimento di Ingegneria Eletronica, Chimica ed Ingegneria Industriale (DIECII), Università di Messina, 98166 Messina (Italy)

    2014-06-01

    The functionalization by nitric acid vapors at azeotropic concentration has been recently proposed to eliminate drawbacks of the widely utilized liquid phase functionalization method. This work suggests to exploit the so-called “salt effect” to improve the vapor phase oxidation method in terms of safety and flexibility. Increasing the relative volatility of acid, the addition of Mg(NO{sub 3}){sub 2} salt to the HNO{sub 3} + H{sub 2}O solution allows (i) obtaining vapors with HNO{sub 3} at the azeotropic concentration from a more diluted liquid solution (i.e. operating under safer conditions), and (ii) varying the concentration of HNO{sub 3} in the vapor phase even above the azeotropic concentration limit (with improved process flexibility). High-resolution transmission electron microscopy, thermo-gravimetry, Raman spectroscopy and X-ray photoemission spectroscopy systematic analyses are carried out on pristine and oxidized nanotubes in order to assess their functionalization degree, surface chemistry and structural evolution. The most relevant finding of this preliminary study is that the nanotube functionalization extent increases linearly with the HNO{sub 3} vapor concentration.

  6. Foliar loading and metabolic assimilation of dry deposited nitric acid air pollutants by trees.

    Science.gov (United States)

    Padgett, Pamela E; Cook, Hillary; Bytnerowicz, Andrzej; Heath, Robert L

    2009-01-01

    Dry deposition of nitric acid vapor (HNO(3)) is a major contributor to eutrophication of natural ecosystems. Although soil fertilization by nitrogen deposition is considered to be the primary pathway for changes in plant nutrient status and shifts in ecological structure, the aerial portion of plants offer many times the surface area in which to collect atmospheric HNO(3). As much as 60% of deposited nitrogen may be retained in the canopy and not land on the soil surface below. Although uptake and assimilation appears to contribute to retention, only a small percentage of dry deposition is recovered in assimilated N pools. To test the importance of biological activity on the process and measurements of dry deposition, we used controlled environmental chambers to compare deposition to living and freeze-dried foliage of four tree species using (15)N-labeled HNO(3). In living trees, assimilation was determined by (15)N incorporation into free amino acids and proteins in leaves and roots. From 10% to 60% of the retained HNO(3) was incorporated into the biologically active nitrogen pool. The remainder was bound to foliar surfaces in an insoluble form in either living or freeze-dried foliage. The importance of the boundary layer conditions emerged as a primary factor controlling dry deposition characteristics and measurements.Trade names and commercial enterprises or products are mentioned solely for information. No endorsements by the U.S. Department of Agriculture are implied.

  7. Treatment process for a surface-active nitric acid solution used for rinsing nuclear installations

    Energy Technology Data Exchange (ETDEWEB)

    Celles, Caroline; Bisel, Isabelle; Gastaldi, Michel; Rudloff, David [CEA Valrho/DEN/VRH/DRCP/SCPS/LPCP, BP 17171, Bagnols sur Ceze cedex, 30207 (France)

    2008-07-01

    Full text of publication follows: The rinsing of the nuclear fuel reprocessing plants before their final shut-down and their dismantling is considered by the use of surface-active compounds in nitric acid medium. Before being vitrified, this solution must be mineralized and concentrated. Two treatments ways have been studied: The first was to act a direct concentration followed up by a mineralization through the Fenton reaction. The second way proposed to begin with the mineralization followed up by a concentration with denitration. The second way was not kept since laboratory tests showed organic phase demixion in distillate which is difficult to manage in industrial plants. The study presents the performance Fenton reaction with a new surface-active solution. In order to be representative of real solution in these nuclear installations to rinse, some hypothesis have been established concerning cations and TBP concentrations, likely to be present in the installation. Influences of parameters like temperature, the nature of the Fenton catalyst, the catalyst concentration, and the concentration of surface-active species were tested. The study highlight the kinetics of the mineralization, the H{sub 2}O{sub 2} consumption, the degradation products of surface-active compounds and TBP. Finally optimized operating conditions have been proposed and a reference test has been performed showing a mineralization out put of about 90% for 167 hours of reaction. Added H{sub 2}O{sub 2} leads to dilute the medium by a factor 2. The main degradation products obtained at the end of reaction are acetic, formic and phosphoric acids. Contrary to acetic and formic acid which will probably be destroyed during following concentration, phosphoric acid behaviour has to be studied in plutonium containing solutions. This study is still in progress. (authors)

  8. Diabetic HDL-associated myristic acid inhibits acetylcholine-induced nitric oxide generation by preventing the association of endothelial nitric oxide synthase with calmodulin.

    Science.gov (United States)

    White, James; Guerin, Theresa; Swanson, Hollie; Post, Steven; Zhu, Haining; Gong, Ming; Liu, Jun; Everson, William V; Li, Xiang-An; Graf, Gregory A; Ballard, Hubert O; Ross, Stuart A; Smart, Eric J

    2008-01-01

    In the current study, we examined whether diabetes affected the ability of HDL to stimulate nitric oxide (NO) production. Using HDL isolated from both diabetic humans and diabetic mouse models, we found that female HDL no longer induced NO synthesis, despite containing equivalent amounts of estrogen as nondiabetic controls. Furthermore, HDL isolated from diabetic females and males prevented acetylcholine-induced stimulation of NO generation. Analyses of both the human and mouse diabetic HDL particles showed that the HDLs contained increased levels of myristic acid. To determine whether myristic acid associated with HDL particles was responsible for the decrease in NO generation, myristic acid was added to HDL isolated from nondiabetic humans and mice. Myristic acid-associated HDL inhibited the generation of NO in a dose-dependent manner. Importantly, diabetic HDL did not alter the levels of endothelial NO synthase or acetylcholine receptors associated with the cells. Surprisingly, diabetic HDL inhibited ionomycin-induced stimulation of NO production without affecting ionomycin-induced increases in intracellular calcium. Further analysis indicated that diabetic HDL prevented calmodulin from interacting with endothelial NO synthase (eNOS) but did not affect the activation of calmodulin kinase or calcium-independent mechanisms for stimulating eNOS. These studies are the first to show that a specific fatty acid associated with HDL inhibits the stimulation of NO generation. These findings have important implications regarding cardiovascular disease in diabetic patients.

  9. The effect of fatty acid surfactants on the uptake of nitric acid to deliquesced NaCl aerosol

    Directory of Open Access Journals (Sweden)

    M. Ammann

    2008-09-01

    Full Text Available Surface active organic compounds have been observed in marine boundary layer aerosol. Here, we investigate the effect such surfactants have on the uptake of nitric acid (HNO3, an important removal reaction of nitrogen oxides in the marine boundary layer. The uptake of gaseous HNO3 on deliquesced NaCl aerosol was measured in a flow reactor using HNO3 labelled with the short-lived radioactive isotope 13N. The uptake coefficient γ on pure deliquesced NaCl aerosol was γ=0.5±0.2 at 60% relative humidity and 30 ppb HNO3(g. The uptake coefficient was reduced by a factor of 5–50 when the aerosol was coated with saturated linear fatty acids with carbon chain lengths of 18 and 15 atoms in monolayer quantities. In contrast, neither shorter saturated linear fatty acids with 12 and 9 carbon atoms, nor coatings with the unsaturated oleic acid (C18, cis-double bond had a detectable effect on the rate of HNO3 uptake. It is concluded that it is the structure of the monolayers formed, which determines their resistance towards HNO3 uptake. Fatty acids (C18 and C15, which form a highly ordered film in the so-called liquid condensed state, represent a significant barrier towards HNO3 uptake, while monolayers of shorter-chain fatty acids (C9, C12 and of the unsaturated oleic acid form a less ordered film in the liquid expanded state and do not hinder the uptake. Similarly, high contents of humic acids in the aerosol, a structurally inhomogeneous, quite water soluble mixture of oxidised high molecular weight organic compounds did not affect HNO3 uptake. As surfactant films on naturally occurring aerosol are expected to be less structured due to their chemical inhomogeneity, it is likely that their inhibitory effect on HNO3 uptake is smaller than that observed here for the C15 and C18 fatty acid monolayers.

  10. Effect of ascorbic acid supplementation on nitric oxide metabolites and systolic blood pressure in rats exposed to lead.

    Science.gov (United States)

    Mohammad, Amani; Ali, Noroozzadeh; Reza, Badalzadeh; Ali, Khoshbaten

    2010-04-01

    Extended exposure to low levels of lead causes high blood pressure in human and laboratory animals. The mechanism is not completely recognized, but it is relatively implicated with generation of free radicals, oxidant agents such as ROS, and decrease of available nitric oxide (NO). In this study, we have demonstrated the effect of ascorbic acid as an antioxidant on nitric oxide metabolites and systolic blood pressure in rats exposed to low levels of lead. The adult male Wistar rats weighing 200-250 g were divided into four groups: control, lead acetate (receiving 100 ppm lead acetate in drinking water), lead acetate plus ascorbic acid (receiving 100 ppm lead acetate and 1 g/l ascorbic acid in drinking water), and ascorbic acid (receiving 1 g/l ascorbic acid in drinking water) groups. The animals were anesthetized with ketamin/xylazine (50 and 7 mg/kg, respectively, ip) and systolic blood pressure was then measured from the tail of the animals by a sphygmomanometer. Nitric oxide levels in serum were measured indirectly by evaluation of its stable metabolites (total nitrite and nitrate (NOchi)). After 8 and 12 weeks, systolic blood pressure in the lead acetate group was significantly elevated compared to the control group. Ascorbic acid supplementation could prevent the systolic blood pressure rise in the lead acetate plus ascorbic acid group and there was no significant difference relative to the control group. The serum NOchi levels in lead acetate group significantly decreased in relation to the control group, but this reduction was not significantly different between the lead acetate plus ascorbic acid group and the control group. Results of this study suggest that ascorbic acid as an antioxidant prevents the lead induced hypertension. This effect may be mediated by inhibition of NOchi oxidation and thereby increasing availability of NO.

  11. Effect of ascorbic acid supplementation on nitric oxide metabolites and systolic blood pressure in rats exposed to lead

    Directory of Open Access Journals (Sweden)

    Mohammad Amani

    2010-01-01

    Full Text Available Background: Extended exposure to low levels of lead causes high blood pressure in human and laboratory animals. The mechanism is not completely recognized, but it is relatively implicated with generation of free radicals, oxidant agents such as ROS, and decrease of available nitric oxide (NO. In this study, we have demonstrated the effect of ascorbic acid as an antioxidant on nitric oxide metabolites and systolic blood pressure in rats exposed to low levels of lead. Materials and Methods: The adult male Wistar rats weighing 200-250 g were divided into four groups: control, lead acetate (receiving 100 ppm lead acetate in drinking water, lead acetate plus ascorbic acid (receiving 100 ppm lead acetate and 1 g/l ascorbic acid in drinking water, and ascorbic acid (receiving 1 g/l ascorbic acid in drinking water groups. The animals were anesthetized with ketamin/xylazine (50 and 7 mg/kg, respectively, ip and systolic blood pressure was then measured from the tail of the animals by a sphygmomanometer. Nitric oxide levels in serum were measured indirectly by evaluation of its stable metabolites (total nitrite and nitrate (NOc. Results: After 8 and 12 weeks, systolic blood pressure in the lead acetate group was significantly elevated compared to the control group. Ascorbic acid supplementation could prevent the systolic blood pressure rise in the lead acetate plus ascorbic acid group and there was no significant difference relative to the control group. The serum NOc levels in lead acetate group significantly decreased in relation to the control group, but this reduction was not significantly different between the lead acetate plus ascorbic acid group and the control group. Conclusion: Results of this study suggest that ascorbic acid as an antioxidant prevents the lead induced hypertension. This effect may be mediated by inhibition of NOc oxidation and thereby increasing availability of NO.

  12. Evaluation of nitric and acetic acid resistance of cement mortars containing high-volume black rice husk ash.

    Science.gov (United States)

    Chatveera, B; Lertwattanaruk, P

    2014-01-15

    This paper presents the performance of cement mortar containing black rice husk ash (BRHA) under nitric and acetic acid attacks. The BRHA, collected from an electrical generating power plant that uses rice husk as fuel, was ground using a grinding machine. The compressive strength loss, weight loss, and expansion of mortars under nitric and acetic acid attack were investigated. The test results of BRHA properties in accordance with the ASTM C 618 standard found that the optimal grinding time was 4 h as this achieved a Blaine fineness of 5370 cm(2)/g. For parametric study, BRHA were used as a Portland cement Type 1 replacement at the levels of 0%, 10%, 20%, 30%, 40%, and 50% by weight of binder. The water-to-binder ratios were 0.55, 0.60, and 0.65. From test results, when the percentage replacements of BRHA in cement increased, it was observed that the strength loss and weight loss of mortars containing BRHA under acetic acid attack were higher than those of the mortars against nitric acid attack. It was found that, of the various BHRA mortars, the strength loss and weight loss due to nitric and acetic acid attacks were the lowest in the mortar with 10% BRHA replacement. For 10%, 20% and 30% BRHA replacements, the rate of expansion of the BRHA mortar decreased when compared with the control mortar. For the mortars with other percentage replacements of BRHA, the rate of expansion increased. Furthermore, the effective water-to-binder ratios of control and BRHA mortars were the primary factor for determining the durability of mortar mixed with BRHA.

  13. RBS/EBS/PIXE measurement of single-walled carbon nanotube modification by nitric acid purification treatment

    Science.gov (United States)

    Jeynes, J. C. G.; Jeynes, C.; Kirkby, K. J.; Rümmeli, M.; Silva, S. R. P.

    2008-04-01

    Single-walled carbon nanotubes (SWCNTs) have many potential applications, including a number of promising biological applications. Nitric acid treatment solubilises CNTs by introducing functional groups, as well as removing amorphous carbon contaminants. Here, we report simultaneous RBS/EBS/PIXE measurements of nitric acid treated SWCNTs, focussing on the metal, nitrogen and oxygen content. We found that nitrogen remains constant in the samples despite washing and dialysis indicating it has either bound irreversibly via intercalation with the SWCNT and/or has been included in functional groups. We also found that the ratio between oxygen and platinum (catalyst) remains constant with treatment time (sampled at 2, 4, 6 h), indicating no more functional groups are made after 2 h exposure.

  14. A New Process Study on Comprehensive Utilization of NOx from Nitric Acid Plant

    Institute of Scientific and Technical Information of China (English)

    Zhou Hou-zhen; Liang Hua

    2003-01-01

    Based on studies of controlling NOx from nitric acid exhaust gas domestic and abroad, this paper has developed a new technique on removal of NOx and production of a by-product with high added value-- MnO2. Experiment shows, pyrolusite, whose valid composition is MnO2, of absorbing NOx has the following characteristics: quick, low cost, no secondary pollutant. Moreover, exhaust gas can attain the required standards. If the temperature of the pyrolusite serum is 30℃, pH=4, containing 90 g/L MnO2, the absorptivity for 3 000 mg/m3 NOx is 89.2%. Furthermore,few of the impurities in pyrolusite dissolve in the absorption mother solution. The purification cost of product is very low.The purity of end product MnO2 is more than 99. 995% after purifying. Therefore, it is workable for the new technique on economy and technology. There are also obvious environmental benefits and marked economic returns.

  15. A New Process Study on Comprehensive Utilization of NOx from Nitric Acid Plant

    Institute of Scientific and Technical Information of China (English)

    ZhouHou-zhen; LiangHua

    2003-01-01

    Based on studies of controlling NOx from nitric acid exhaust gas domestic and abroad, this paper has developed a new technique on removal of NOx and production of a by-product with high added value MnO2. Experiment shows, pyrolusite, whose valid composition is MnO2, of absorbing NOx has the following characteristics: quick, low cost, no secondary pollutant. Moreover, exhaust gas can attain the required standards. If the temperature of the pyrolusite serum is 30℃, pH=4, containing 90 g/L MnO2, the absorptivity for 3 000 mg/m3 NOx is 89.2%. Furthermore,few of the impurities in pyrolusite dissolve in the absorption mother solution. The purification cost of product is very low.The purity of end product MnO2 is more than 99. 995% after purifying. Therefore, it is workable for the new technique on economy and technology. There are also obvious environmental benefits and marked economic returns.

  16. Involvement of nitric oxide in the signal transduction of salicylic acid regulating stomatal movement

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The effects and the relationship between salicylic acid (SA) and nitric oxide (NO) on Vicia faba L. stomatal movement were studied. The results here showed that exogenous SA and NO induced stomatal closure, 100 μmol/L SA induced a rapid and striking NO increase in the cytosol of guard cells. This phenomenon was largely pre-vented by 200 μmol/L 2-phenyl-4,4,5,5-tetramethylimida-zoline-1-oxyl-3-oxide (PTIO), a specific NO scavenger, and 25 μmol/L NG-nitro-L-Arg-methyl eater (L-NAME), an in-hibitor of NO synthase (NOS) in mammalian cells that also inhibits plant NOS. In addition, SA-induced stomatal closure was largely prevented by PTIO and L-NAME. These results provide evidence that guard cells generate NO in response to SA via NOS-like activity, and that such NO production is required for full stomatal closure in response to SA. H-(1,2,4)-oxadiazole-[4,3-α]quinoxalin-1-one (ODQ), an inhibitor of guanylate cyclase, and nicotinamide, an antago-nist of cADPR production, inhibited the effects of SA- and NO-induced stomatal closure. It suggests that both cGMP and cADPR might mediate the signal transduction of SA and NO-induced stomatal closure.

  17. Sphere of influence of indole acetic acid and nitric oxide in bacteria.

    Science.gov (United States)

    Koul, Vatsala; Adholeya, Alok; Kochar, Mandira

    2015-05-01

    Bacterial biosynthesis of the phytohormone, indole-3-acetic acid (IAA) is well established and along with the diffusible gaseous molecule, nitric oxide (NO) is known to positively regulate the developmental processes of plant roots. IAA and NO act as signaling molecules in plant-microbe interactions as they modulate the gene expression in both, plants and microorganisms. Although IAA and NO may not be required for essential bacterial physiological processes, numerous studies point towards a crosstalk between IAA and NO in the rhizosphere. In this review, we describe various IAA and NO-responsive or sensing genes/proteins/regulators. There is also growing evidence for the interaction of IAA and NO with other plant growth regulators and the involvement of NO with the quorum sensing system in biofilm formation and virulence. This interactive network can greatly impact the host plant-microbe interactions in the soil. Coupled with this, the specialized σ(54) -dependent transcription observed in some of the IAA and NO-influenced genes can confer inducibility to these traits in bacteria and may allow the expression of IAA and NO-influenced microbial genes in nutrient limiting or changing environmental conditions for the benefit of plants.

  18. Characteristic of wet method of phosphorus recovery from polish sewage sludge ash with nitric acid

    Directory of Open Access Journals (Sweden)

    Gorazda Katarzyna

    2016-01-01

    Full Text Available Sewage Sludge Ash (SSA is a concentrated source of phosphorus and can be successfully recycled via a number of different routes. This paper presents research results on phosphorus recovery from differently combusted sewage sludge with the use of nitric acid extraction. Different SSA forms from Polish thermal utilization stations were compared. It was revealed that sewage treatment technology as well as combustion technology influence many physical and chemical parameters of ashes that are crucial for further phosphorus recovery from such waste according to the proposed method. Presented research defines extraction efficiency, characterized extracts composition and verifies the possibility of using SSA as cheaper and alternative sources of phosphorus compounds. Gdynia, Kielce and Kraków SSA have the best properties for the proposed technology of phosphorus recovery with high extraction efficiency greater than 86%. Unsuitable results were obtained for Bydgoszcz, Szczecin Slag and Warszawa SSA. Extraction process for Łódź and Szczecin Dust SSA need to be improved for a higher phosphorus extraction efficiency greater than 80%.

  19. Effects of composite restorations on nitric oxide and uric acid levels in saliva

    Directory of Open Access Journals (Sweden)

    Nilgun Akgul

    2015-01-01

    Full Text Available Background and Aims: Dental materials that are used in dentistry should be harmless to oral tissues, and should, therefore, not contain any leachable toxic and diffusible substances capable of causing side effects. This study was intended to investigate the effects on salivary nitric oxide (NO and uric acid (UA levels after application of dental composite filling materials to healthy volunteers. Materials and Methods: A total of 52 individuals (32 female and 20 male participated in the study. Filtek Z250 composite filling material (3M ESPE, St Paul, MN, USA was applied to healthy volunteers. Saliva samples were collected before restoration (baseline and 1 h, 1-day, 7 days, and 30 days after restoration. NO concentrations were measured using the Griess reaction method, and UA was measured using an enzymatic method. Data were analyzed using repeated measures ANOVA and the Bonferroni post-hoc test (α =5%. Results: NO values increased statistically significant after 7 days (P 0.05. There was no correlation between NO and UA levels in saliva (P > 0.05. Conclusion: Composite resins activated the antioxidant system in saliva. However, further studies are now needed to confirm our findings and to permit a definitive conclusion.

  20. Ambient concentrations of atmospheric ammonia, nitrogen dioxide and nitric acid in an intensive agricultural region

    Science.gov (United States)

    Zbieranowski, Antoni L.; Aherne, Julian

    2013-05-01

    The spatial and temporal distribution of ambient atmospheric gaseous reactive nitrogen (Nr) species concentrations (ammonia [NH3], nitrogen dioxide [NO2] and nitric acid [HNO3]) were measured at the field scale in an intensive agricultural region in southern Ontario, Canada. Atmospheric concentrations were measured with the Willems badge diffusive passive sampler (18 sites for NH3, 9 sites for NO2 and HNO3) for one year (April 2010-March 2011; under a two week measurement frequency) within a 15 km × 15 km area. Dry deposition was calculated using the inferential method and estimated across the entire study area. The spatial distribution of emission sources associated with agricultural activity resulted in high spatial variability in annual average ambient NH3 concentrations (8 μg m-3 within a 2 km distance, coefficient of variation ˜50%) and estimated dry deposition (4-13 kg N ha-1 yr-1) between sample sites. In contrast, ambient concentrations and deposition of both NO2 (˜5.2->6.5 μg m-3; 1.0-1.5 kg N ha-1 yr-1) and HNO3 (0.6-0.7 μg m-3; 0.5-1 kg N ha-1 yr-1) had low variability (coefficient of variation mycorrhiza and ground vegetation within adjacent semi-natural ecosystems (estimated at ˜10% of the study area).

  1. Investigations of the inhibition of copper corrosion in nitric acid solutions by ketene dithioacetal derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Fiala, A. [Laboratoire de chimie moleculaire du controle de l' environnement et des mesures physico-chimiques, faculte des sciences exactes, universite Mentouri-Constantine, route de Ain-El-Bey, Constantine (Algeria)], E-mail: abdelfiala@yahoo.fr; Chibani, A. [Laboratoire de chimie moleculaire du controle de l' environnement et des mesures physico-chimiques, faculte des sciences exactes, universite Mentouri-Constantine, route de Ain-El-Bey, Constantine (Algeria); Darchen, A. [Laboratoire d' electrochimie, ecole nationale superieure de chimie de Rennes, avenue du general-Leclerc, 35700 Rennes (France); Boulkamh, A.; Djebbar, K. [Laboratoire de chimie moleculaire du controle de l' environnement et des mesures physico-chimiques, faculte des sciences exactes, universite Mentouri-Constantine, route de Ain-El-Bey, Constantine (Algeria)

    2007-10-15

    Ketene dithioacetal derivatives, namely 3-[bis(methylthio)methylene] pentane-2,4-dione (1), 3-(1,3-dithian-2-ylidene) pentane-2,4-dione (2) and 3-(1,3-dithiolan-2-ylidene) pentane-2,4-dione (3) were synthesized and their respective capacity to inhibit copper corrosion in 3 M HNO{sub 3} was investigated by means of weight loss, potentiodynamic polarization, scanning electron microscopy (SEM) and energy dispersive X-ray fluorescence (XRF). The obtained results indicate that the addition of these compounds significantly decreases the corrosion rate. Potentiodynamic polarization studies clearly showed that the inhibition efficiency increases with increasing concentration of the investigated compounds at a fixed temperature, but decreases with increasing temperature. These results on the whole showed that the studied substances are good cathodic inhibitors for copper corrosion in nitric acid medium. SEM and energy dispersive X-ray (EDAX) examination of the copper surface revealed that these compounds prevented copper from corrosion by adsorption on its surface to form a protective film, which acts as a barrier to aggressive agents. The presence of these organic compounds adsorbed on the electrode surface was confirmed by XRF investigations.

  2. Heterogeneous formation of polar stratospheric clouds – Part 1: Nucleation of nitric acid trihydrate (NAT

    Directory of Open Access Journals (Sweden)

    C. R. Hoyle

    2013-09-01

    Full Text Available Satellite-based observations during the Arctic winter of 2009/2010 provide firm evidence that, in contrast to the current understanding, the nucleation of nitric acid trihydrate (NAT in the polar stratosphere does not only occur on preexisting ice particles. In order to explain the NAT clouds observed over the Arctic in mid-December 2009, a heterogeneous nucleation mechanism is required, occurring via immersion freezing on the surface of solid particles, likely of meteoritic origin. For the first time, a detailed microphysical modelling of this NAT formation pathway has been carried out. Heterogeneous NAT formation was calculated along more than sixty thousand trajectories, ending at Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP observation points. Comparing the optical properties of the modelled NAT with these observations enabled a thorough validation of a newly developed NAT nucleation parameterisation, which has been built into the Zurich Optical and Microphysical box Model (ZOMM. The parameterisation is based on active site theory, is simple to implement in models and provides substantial advantages over previous approaches which involved a constant rate of NAT nucleation in a given volume of air. It is shown that the new method is capable of reproducing observed polar stratospheric clouds (PSCs very well, despite the varied conditions experienced by air parcels travelling along the different trajectories. In a companion paper, ZOMM is applied to a later period of the winter, when ice PSCs are also present, and it is shown that the observed PSCs are also represented extremely well under these conditions.

  3. Folic acid supplementation improves microvascular function in older adults through nitric oxide-dependent mechanisms.

    Science.gov (United States)

    Stanhewicz, Anna E; Alexander, Lacy M; Kenney, W Larry

    2015-07-01

    Older adults have reduced vascular endothelial function, evidenced by attenuated nitric oxide (NO)-dependent cutaneous vasodilatation. Folic acid and its metabolite, 5-methyltetrahydrofolate (5-MTHF), are reported to improve vessel function. We hypothesized that (i) local 5-MTHF administration and (ii) chronic folic acid supplementation would improve cutaneous microvascular function in ageing through NO-dependent mechanisms. There were two separate studies in which there were 11 young (Y: 22 ± 1 years) and 11 older (O: 71 ± 3 years) participants. In both studies, two intradermal microdialysis fibres were placed in the forearm skin for local delivery of lactated Ringer's solution with or without 5 mM 5-MTHF. Red cell flux was measured by laser-Doppler flowmetry. Cutaneous vascular conductance [CVC=red cell flux/mean arterial pressure] was normalized as percentage maximum CVC (%CVCmax) (28 mM sodium nitroprusside, local temperature 43°C). In study 1 after CVC plateaued during local heating, 20 mM NG-nitro-L-arginine methyl ester (L-NAME) was perfused at each site to quantify NO-dependent vasodilatation. The local heating plateau (%CVCmax: O = 82 ± 3 vs Y = 96 ± 1, P = 0.002) and NO-dependent vasodilatation (%CVCmax: O = 26 ± 6% vs Y = 49 ± 5, P = 0.03) were attenuated in older participants. 5-MTHF augmented the overall (%CVCmax = 91 ± 2, P = 0.03) and NO-dependent (%CVCmax = 43 ± 9%, P = 0.04) vasodilatation in older but not young participants. In study 2 the participants ingested folic acid (5 mg/day) or placebo for 6 weeks in a randomized, double-blind, crossover design. A rise in oral temperature of 1°C was induced using a water-perfused suit, body temperature was held and 20 mM L-NAME was perfused at each site. Older participants had attenuated reflex (%CVCmax: O = 31 ± 8 vs Y = 44 ± 5, P = 0.001) and NO-dependent (%CVCmax: O = 9 ± 2 vs Y = 21 ± 2, P = 0.003) vasodilatation. Folic acid increased CVC (%CVCmax = 47 ± 5%, P = 0.001) and NO

  4. Corrosion investigations on zircaloy-4 and titanium dissolver materials for MOX fuel dissolution in concentrated nitric acid containing fluoride ions

    Energy Technology Data Exchange (ETDEWEB)

    Jayaraj, J.; Krishnaveni, P.; Krishna, D. Nanda Gopala; Mallika, C.; Mudali, U. Kamachi, E-mail: kamachi@igcar.gov.in

    2016-05-15

    Aqueous reprocessing of plutonium-rich mixed oxide fuels require fluoride as a dissolution catalyst in boiling nitric acid for an effective dissolution of the spent fuel. High corrosion rates were obtained for the candidate dissolver materials zircaloy-4 (Zr-4) and commercial pure titanium (CP-Ti grade 2) in boiling 11.5 M HNO{sub 3} + 0.05 M NaF. Complexing the fluoride ions either with Al(NO{sub 3}){sub 3} or ZrO(NO{sub 3}){sub 2} aided in decreasing the corrosion rates of Zr-4 and CP-Ti. From the obtained corrosion rates it is concluded that CP-Ti is a better dissolver material than Zr-4 for extended service life in boiling 11.5 M HNO{sub 3} + 0.05 M NaF, when complexed with 0.15 M ZrO(NO{sub 3}){sub 2}. XPS analysis confirmed the presence of TiO{sub 2} and absence of fluoride on the surface of CP-Ti samples, indicating that effective complexation had occurred in solution leading to passivation of the metal and imparting high corrosion resistance. - Highlights: • Zr-4 and CP-Ti exhibited high corrosion rate in boiling fluorinated nitric acid. • Corrosion rate decreased in fluorinated nitric acid containing ZrO(NO{sub 3}){sub 2} and Al(NO{sub 3}){sub 3}. • High inhibiting efficiency is exhibited by 0.15 M ZrO(NO{sub 3}){sub 2} when compared to Al(NO{sub 3}){sub 3}. • Corrosion rates of CP-Ti were negligible in complexed fluorinated nitric acid. • XPS analysis on CP-Ti confirmed the presence of TiO{sub 2} and absence of fluoride.

  5. Accurate quantification and transformation of arsenic compounds during wet ashing with nitric acid and microwave assisted heating.

    Science.gov (United States)

    Goessler, W; Pavkov, M

    2003-06-01

    Arsenous acid, dimethylarsinic acid (DMA), methylarsonic acid (MA), arsenic acid, arsenobetaine bromide (AB), trimethylarsine oxide (TMAO), arsenocholine iodide (AC), and tetramethylarsonium iodide (TETRA) were heated in a microwave autoclave with nitric acid to 100-300 degrees C. The arsenic compounds in the digests were separated with anion- and cation-exchange chromatography and determined with an inductively coupled plasma mass spectrometer as arsenic-specific detector. Arsenous acid was completely oxidized to arsenic acid at 100 degrees C. For a complete oxidation of MA and DMA to arsenic acid temperatures > 220 degrees C and > 280 degrees C were necessary. AB decomposed to arsenic acid via TMAO. Complete conversion was only obtained after heating the sample for 90 min to 300 degrees C. For a complete conversion of TMAO similar harsh conditions were necessary. AC was already substantially degraded to TMAO, TETRA and two unknown compounds at 100 degrees C. The unknown arsenic compounds were found only in the digests up to 160 degrees C. Quantitative conversion of AC to arsenic acid went also via TMAO. At temperatures above 220 degrees C TETRA started to convert to TMAO, which then was further converted to arsenic acid. To investigate whether the results obtained for the arsenic standards are transferable to real samples, the certified reference material DORM-2 was also heated in nitric acid with variable digestion temperatures and times. For an almost complete conversion of the AB present in DORM-2 90 min at 300 degrees C were necessary. Total organic carbon (TOC) was less or = 260 degrees C for 60 min. UV photo-oxidation of DORM-2 was investigated as an alternative sample decomposition. Only 6% of AB was converted to arsenic acid when DORM-2 was irradiated for 2 h at 1000 W. In contrast to microwave heating substantial amounts of MA were observed as degradation product.

  6. Thermal And Spectroscopic Analyses Of Next Generation Caustic Side Solvent Extraction Solvent Contacted With 3, 8, And 16 Molar Nitric Acid

    Energy Technology Data Exchange (ETDEWEB)

    Fondeur, F. F.; Fink, S. D.

    2011-12-07

    A new solvent system referred to as Next Generation Solvent or NGS, has been developed at Oak Ridge National Laboratory for the removal of cesium from alkaline solutions in the Caustic Side Solvent Extraction process. The NGS is proposed for deployment at MCU{sup a} and at the Salt Waste Processing Facility. This work investigated the chemical compatibility between NGS and 16 M, 8 M, and 3 M nitric acid from contact that may occur in handling of analytical samples from MCU or, for 3 M acid, which may occur during contactor cleaning operations at MCU. This work shows that reactions occurred between NGS components and the high molarity nitric acid. Reaction rates are much faster in 8 M and 16 M nitric acid than in 3 M nitric acid. In the case of 16 M and 8 M nitric acid, the nitric acid reacts with the extractant to produce initially organo-nitrate species. The reaction also releases soluble fluorinated alcohols such as tetrafluoropropanol. With longer contact time, the modifier reacts to produce a tarry substance with evolved gases (NO{sub x} and possibly CO). Calorimetric analysis of the reaction product mixtures revealed that the organo-nitrates reaction products are not explosive and will not deflagrate.

  7. Remedial investigation report on the abandoned nitric acid pipeline at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    Energy Technology Data Exchange (ETDEWEB)

    1993-12-01

    Upper East Fork Poplar Creek OU-2 consists of the Abandoned Nitric Acid Pipeline. This pipeline was installed in 1951 to transport liquid wastes {approximately} 4,800 ft from Buildings 9212, 9215, and 9206 to the S-3 Ponds. Materials known to have been discharged through the pipeline include nitric acid, depleted and enriched uranium, various metal nitrates, salts, and lead skimmings. A total of nineteen locations were chosen to be investigated along the pipeline for the first phase of this Remedial Investigation. Sampling consisted of drilling down to obtain a soil sample at a depth immediately below the pipeline. Additional samples were obtained deeper in the subsurface depending upon the depth of the pipeline, the depth of the water table, and the point of auger refusal. The nineteen samples collected below the pipeline were analyzed by the Y-12 Plant laboratory for metals, nitrate/nitrite, and isotopic uranium. Samples collected from three boreholes were also analyzed for volatile organic compounds because these samples produced a response with organic vapor monitoring equipment. The results of the baseline human health risk assessment for the Abandoned Nitric Acid Pipeline contaminants of potential concern show no unacceptable risks to human health via incidental ingestion of soil, inhalation of dust, dermal contact with the soil, or external exposure to radionuclides in the ANAP soils, under the construction worker and/or the residential land-use scenarios.

  8. Study on reduction and back extraction of Pu(IV) by urea derivatives in nitric acid conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ye, G.A.; Xiao, S.T.; Yan, T.H.; Lin, R.S.; Zhu, Z.W. [China Institute of Atomic Energy, P.O.Box 275(26), Beijing 102413 (China)

    2013-07-01

    The reduction kinetics of Pu(IV) by hydroxyl-semicarbazide (HSC), hydroxyurea (HU) and di-hydroxyurea (DHU) in nitric acid solutions were investigated separately with adequate kinetic equations. In addition, counter-current cascade experiments were conducted for Pu split from U in nitric acid media using three kinds of reductant, respectively. The results show that urea derivatives as a kind of novel salt-free reductant can reduce Pu(IV) to Pu(III) rapidly in the nitric acid solutions. The stripping experimental results showed that Pu(IV) in the organic phase can be stripped rapidly to the aqueous phase by the urea derivatives, and the separation factors of plutonium /uranium can reach more than 10{sup 4}. This indicates that urea derivatives is a kind of promising salt-free agent for uranium/plutonium separation. In addition, the complexing effect of HSC with Np(IV) was revealed, and Np(IV) can be back-extracted by HSC with a separation factor of about 20.

  9. Development of a Quantum Cascade Laser-Based Detector for Ammonia and Nitric Acid

    Energy Technology Data Exchange (ETDEWEB)

    Zahniser, Mark S.; Nelson, David D.; McManus, J. Barry; Shorter, Joanne H.; Herndon, Scott C.; Jimenez, Rodrigo

    2005-12-31

    We have developed a compact, robust, atmospheric trace gas detector based on mid-infrared absorption spectroscopy using pulsed quantum cascade (QC) lasers. The spectrometer is suitable for airborne measurements of ammonia, nitric acid, formaldehyde, formic acid, methane, nitrous oxide, carbon monoxide, nitrogen dioxide and other gases that have line-resolved absorption spectra in the mid-infrared spectral region. The QC laser light source operates near room temperature with thermal electric cooling instead of liquid nitrogen which has been previously required for semiconductor lasers in the mid-infrared spectral region. The QC lasers have sufficient output power so that thermal electric cooled detectors may be used in many applications with lower precision requirements. The instrument developed in this program has been used in several field campaigns from both the Aerodyne Mobile Laboratory and from the NOAA WP3 aircraft. The Phase II program has resulted in more than 10 archival publications describing the technology and its applications. Over 12 instruments based on this design have been sold to research groups in Europe and the United States making the program both a commercial as well as a technological success. Anticipated Benefits The development of a sensitive, cryogen-free, mid-infrared absorption method for atmospheric trace gas detection will have wide benefits for atmospheric and environmental research and broader potential commercial applications in areas such as medical diagnostic and industrial process monitoring of gaseous compounds. Examples include air pollution monitoring, breath analysis, combustion exhaust diagnostics, and plasma diagnostics for semi-conductor fabrication. The substitution of near-room temperature QC lasers for cryogenic lead salt TDLs and the resulting simplifications in instrument design and operation will greatly expand the range of applications.

  10. Fast and Simultaneous Determination of Pu(Ⅳ) and Nitric Acid in Spent Nuclear Fuel Reprocessing Sample by Near Infrared Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    LI; Ding-ming; ZHANG; Li-hua; WANG; Ling; GONG; Yan-ping; FAN; De-jun; YI; Bao-shan; CHEN; Qiang; JI; Yong-chao; WU; Ji-zong

    2013-01-01

    Determination of Pu(Ⅳ)and nitric acid plays significant role in nuclear fuel reprocessing plant to control process accurately and timely.Coupling C-T fixed-type grating with InGaAs detector,a new novel analytical system for simultaneous measurement of nitric acid and Pu(Ⅳ)was developed by our working group.After obtaining near infrared absorptive spectra by the spectroscopic instrument,the spectra data

  11. Interaction of plutonium(iv) with mono-n-butylphosphoric acid in nitric acid solutions and in the system 30% TBP + n-dodecane

    Energy Technology Data Exchange (ETDEWEB)

    Rovnyi, S.I.; Boikova, I.A.; Fedoseev, D.A.; Goncharuk, L.V.; Milovanova, A.S.; Sokhina, L.P.

    1986-03-01

    The methods of elementary and spectrophotometric analysis at the temperature 22 + or - 2 degrees C were used to investigate the interaction of mono-n-butylphosphoric acid (MBPA, H/sub 2/B) with Pu(IV) in nitric acid solutions and in the system 30% TBP + n-dodecane. The conditions of formatin, solubility, and composition of precipitates of MBPA with Pu(OV) were investigated; the effective stability constants K of complexes of Pu(IV) with MBPA of various compositions were determined. The results of the studies are discussed in comparison with the interaction of Zn(IV) with MBPA in nitric acid solutions and in the system 30% TBP + n-dodecane.

  12. Low Temperature Selective Catalytic Reduction of Nitrogen Oxides in Production of Nitric Acid by the Use of Liquid

    Directory of Open Access Journals (Sweden)

    Kabljanac, Ž.

    2011-11-01

    Full Text Available This paper presents the application of low-temperature selective catalytic reduction of nitrous oxides in the tail gas of the dual-pressure process of nitric acid production. The process of selective catalytic reduction is carried out using the TiO2/WO3 heterogeneous catalyst applied on a ceramic honeycomb structure with a high geometric surface area per volume. The process design parameters for nitric acid production by the dual-pressure procedure in a capacity range from 75 to 100 % in comparison with designed capacity for one production line is shown in the Table 1. Shown is the effectiveness of selective catalytic reduction in the temperature range of the tail gas from 180 to 230 °C with direct application of liquid ammonia, without prior evaporation to gaseous state. The results of inlet and outlet concentrations of nitrous oxides in the tail gas of the nitric acid production process are shown in Figures 1 and 2. Figure 3 shows the temperature dependence of the selective catalytic reduction of nitrous oxides expressed as NO2in the tail gas of nitric acid production with the application of a constant mass flow of liquid ammonia of 13,0 kg h-1 and average inlet mass concentration of the nitrous oxides expressed as NO2of 800,0 mgm-3 during 100 % production capacity. The specially designed liquid-ammonia direct-dosing system along with the effective homogenization of the tail gas resulted in emission levels of nitrous oxides expressed as NO2 in tail gas ranging from 100,0 to 185,0 mg m-3. The applied low-temperature selective catalytic reduction of the nitrous oxides in the tail gases by direct use of liquid ammonia is shown in Figure 4. It is shown that low-temperature selective catalytic reduction with direct application of liquid ammonia opens a new opportunity in the reduction of nitrous oxide emissions during nitric acid production without the risk of dangerous ammonium nitrate occurring in the process of subsequent energy utilization of

  13. A comparison of copper and acid site zeolites for the production of nitric oxide for biomedical applications.

    Science.gov (United States)

    Russell, Samantha E; González Carballo, Juan María; Orellana-Tavra, Claudia; Fairen-Jimenez, David; Morris, Russell E

    2017-03-21

    Copper-exchanged and acidic zeolites are shown to produce nitric oxide (NO) from a nitrite source in biologically active (nanomolar) concentrations. Four zeolites were studied; mordenite, ferrierite, ZSM-5 and SSZ-13, which had varying pore size, channel systems and Si/Al ratios. ZSM-5 and SSZ-13 produced the highest amounts of NO in both the copper and acid form. The high activity and regeneration of the copper active sites makes them good candidates for long-term NO production. Initial cytotoxicity tests have shown at least one of the copper zeolites (Cu-SSZ-13) to be biocompatible, highlighting the potential usage within biomedical applications.

  14. DISSOLUTION OF PLUTONIUM METAL USING NITRIC ACID SOLUTIONS CONTAINING POTASSIUM FLUORIDE

    Energy Technology Data Exchange (ETDEWEB)

    Rudisill, T.; Crowder, M.; Bronikowski, M.

    2007-10-15

    The deinventory and deactivation of the Savannah River Site's (SRS's) FB-Line facility required the disposition of approximately 2000 items from the facility's vaults. Plutonium (Pu) scraps and residues which do not meet criteria for conversion to a mixed oxide fuel will be dissolved and the solution stored for subsequent disposition. Some of the items scheduled for dissolution are composite materials containing Pu and tantalum (Ta) metals. The preferred approach for handling this material is to dissolve the Pu metal, rinse the Ta metal with water to remove residual acid, and burn the Ta metal. The use of a 4 M nitric acid (HNO{sub 3}) solution containing 0.2 M potassium fluoride (KF) was initially recommended for the dissolution of approximately 500 g of Pu metal. However, prior to the use of the flowsheet in the SRS facility, a new processing plan was proposed in which the feed to the dissolver could contain up to 1250 g of Pu metal. To evaluate the use of a larger batch size and subsequent issues associated with the precipitation of plutonium-containing solids from the dissolving solution, scaled experiments were performed using Pu metal and samples of the composite material. In the initial experiment, incomplete dissolution of a Pu metal sample demonstrated that a 1250 g batch size was not feasible in the HB-Line dissolver. Approximately 45% of the Pu was solubilized in 4 h. The remaining Pu metal was converted to plutonium oxide (PuO{sub 2}). Based on this work, the dissolution of 500 g of Pu metal using a 4-6 h cycle time was recommended for the HB-Line facility. Three dissolution experiments were subsequently performed using samples of the Pu/Ta composite material to demonstrate conditions which reduced the risk of precipitating a double fluoride salt containing Pu and K from the dissolving solution. In these experiments, the KF concentration was reduced from 0.2 M to either 0.15 or 0.175 M. With the use of 4 M HNO{sub 3} and a reduction in

  15. Optimization of conditions to produce nitrous gases by electrochemical reduction of nitric acid; Optimisation des conditions operatoires de production de vapeurs nitreuses par reduction electrochimique d`acide nitrique

    Energy Technology Data Exchange (ETDEWEB)

    Lemaire, M. [CEA Centre d`Etudes Nucleaires de Saclay, 91 -Gif-sur-Yvette (France)]|[CEA Centre d`Etudes de la Vallee du Rhone, 30 -Marcoule (France). Direction du Cycle du Combustible

    1996-11-22

    Gaseous nitrogen oxides (NO and NO{sub 2}) involved as oxidizing agents in nuclear fuel reprocessing can be an produced by electrochemical reduction of nitric acid. This could be an interesting alternative to the usual process because no wastes are generated. Voltammetric studies on a platinum electrode show that two reduction potential regions are observed in concentrated nitric acid solutions, between 0.05 V{sub S}HE and 0.3 V{sub S}HE and O.5 V{sub S}HE and 1 V{sub S}HE. The highest potential region reduction mechanism was studies by: classical micro-electrolysis methods; macro-electrolysis methods; infra-red spectroscopy couplet to electrochemistry. It was determined that the origin of nitric acid reduction is the electrochemical reduction of nitrous acid in nitric oxide which chemically reduces nitric acid. This reaction produces nitrous acid back which indicate an auto-catalytic behaviour of nitric acid reduction mechanism. Nitrogen dioxide evolution during nitric acid reduction can also be explained by an other chemical reaction. In the potential value of platinum electrode is above 0.8 V{sub S}HE, products of the indirect nitric acid reduction are nitrous acid, nitrogen oxide and nitrogen dioxide. Below this value nitric oxide can be reduced in nitrous oxide. Thus the potential value is the most important parameter for the nitrogen oxides production selectivity. However, owing to the auto-catalytic character of the reduction mechanism, potential value can be controlled during intentiostatic industrial electrolysis. (author). 91 refs.

  16. Nitric oxide-releasing poly(lactic-co-glycolic acid)-polyethylenimine nanoparticles for prolonged nitric oxide release, antibacterial efficacy, and in vivo wound healing activity.

    Science.gov (United States)

    Nurhasni, Hasan; Cao, Jiafu; Choi, Moonjeong; Kim, Il; Lee, Bok Luel; Jung, Yunjin; Yoo, Jin-Wook

    2015-01-01

    Nitric oxide (NO)-releasing nanoparticles (NPs) have emerged as a wound healing enhancer and a novel antibacterial agent that can circumvent antibiotic resistance. However, the NO release from NPs over extended periods of time is still inadequate for clinical application. In this study, we developed NO-releasing poly(lactic-co-glycolic acid)-polyethylenimine (PEI) NPs (NO/PPNPs) composed of poly(lactic-co-glycolic acid) and PEI/diazeniumdiolate (PEI/NONOate) for prolonged NO release, antibacterial efficacy, and wound healing activity. Successful preparation of PEI/NONOate was confirmed by proton nuclear magnetic resonance, Fourier transform infrared spectroscopy, and ultraviolet/visible spectrophotometry. NO/PPNPs were characterized by particle size, surface charge, and NO loading. The NO/PPNPs showed a prolonged NO release profile over 6 days without any burst release. The NO/PPNPs exhibited potent bactericidal efficacy against methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa concentration-dependently and showed the ability to bind on the surface of the bacteria. We also found that the NO released from the NO/PPNPs mediates bactericidal efficacy and is not toxic to healthy fibroblast cells. Furthermore, NO/PPNPs accelerated wound healing and epithelialization in a mouse model of a MRSA-infected wound. Therefore, our results suggest that the NO/PPNPs presented in this study could be a suitable approach for treating wounds and various skin infections.

  17. Thermal transformation of bioactive caffeic acid on fumed silica seen by UV-Vis spectroscopy, thermogravimetric analysis, temperature programmed desorption mass spectrometry and quantum chemical methods.

    Science.gov (United States)

    Kulik, Tetiana V; Lipkovska, Natalia O; Barvinchenko, Valentyna M; Palyanytsya, Borys B; Kazakova, Olga A; Dudik, Olesia O; Menyhárd, Alfréd; László, Krisztina

    2016-05-15

    Thermochemical studies of hydroxycinnamic acid derivatives and their surface complexes are important for the pharmaceutical industry, medicine and for the development of technologies of heterogeneous biomass pyrolysis. In this study, structural and thermal transformations of caffeic acid complexes on silica surfaces were studied by UV-Vis spectroscopy, thermogravimetric analysis, temperature programmed desorption mass spectrometry (TPD MS) and quantum chemical methods. Two types of caffeic acid surface complexes are found to form through phenolic or carboxyl groups. The kinetic parameters of the chemical reactions of caffeic acid on silica surface are calculated. The mechanisms of thermal transformations of the caffeic chemisorbed surface complexes are proposed. Thermal decomposition of caffeic acid complex chemisorbed through grafted ester group proceeds via three parallel reactions, producing ketene, vinyl and acetylene derivatives of 1,2-dihydroxybenzene. Immobilization of phenolic acids on the silica surface improves greatly their thermal stability.

  18. Modulation of Ionotropic Glutamate Receptors and Acid-Sensing Ion Channels by Nitric Oxide

    Directory of Open Access Journals (Sweden)

    John Q Wang

    2012-05-01

    Full Text Available Ionotropic glutamate receptors (iGluR are ligand-gated ion channels and are densely expressed in broad areas of mammalian brains. Like iGluRs, acid-sensing ion channels (ASIC are ligand (H+-gated channels and are enriched in brain cells and peripheral sensory neurons. Both ion channels are enriched at excitatory synaptic sites, functionally coupled to each other, and subject to the modulation by a variety of signaling molecules. Central among them is a gasotransmitter, nitric oxide (NO. Available data show that NO activity-dependently modulates iGluRs and ASICs via either a direct or an indirect pathway. The former involves a NO-based and cGMP-independent posttranslational modification (S-nitrosylation of extracellular cysteine residues in channel subunits or channel-interacting proteins. The latter is achieved by NO activation of soluble guanylyl cyclase, which in turn triggers an intracellular cGMP-sensitive cascade to indirectly modulate iGluRs and ASICs. The NO modification is usually dynamic and reversible. Modified channels undergo significant, interrelated changes in biochemistry and electrophysiology. Since NO synthesis is enhanced in various neurological disorders, the NO modulation of iGluRs and ASICs is believed to be directly linked to the pathogenesis of these disorders. This review summarizes the direct and indirect modifications of iGluRs and ASICs by NO and analyzes the role of the NO-iGluR and NO-ASIC coupling in cell signaling and in the pathogenesis of certain related neurological diseases.

  19. Ab initio aqueous thermochemistry: application to the oxidation of hydroxylamine in nitric acid solution.

    Science.gov (United States)

    Ashcraft, Robert W; Raman, Sumathy; Green, William H

    2007-10-18

    Ab initio molecular orbital calculations were performed and thermochemical parameters estimated for 46 species involved in the oxidation of hydroxylamine in aqueous nitric acid solution. Solution-phase properties were estimated using the several levels of theory in Gaussian03 and using COSMOtherm. The use of computational chemistry calculations for the estimation of physical properties and constants in solution is addressed. The connection between the pseudochemical potential of Ben-Naim and the traditional standard state-based thermochemistry is shown, and the connection of these ideas to computational chemistry results is established. This theoretical framework provides a basis for the practical use of the solution-phase computational chemistry estimates for real systems, without the implicit assumptions that often hide the nuances of solution-phase thermochemistry. The effect of nonidealities and a method to account for them is also discussed. A method is presented for estimating the solvation enthalpy and entropy for dilute aqueous solutions based on the solvation free energy from the ab initio calculations. The accuracy of the estimated thermochemical parameters was determined through comparison with (i) enthalpies of formation in the gas phase and in solution, (ii) Henry's law data for aqueous solutions, and (iii) various reaction equilibria in aqueous solution. Typical mean absolute deviations (MAD) for the solvation free energy in room-temperature water appear to be ~1.5 kcal/mol for most methods investigated. The MAD for computed enthalpies of formation in solution was 1.5-3 kcal/mol, depending on the methodology employed and the type of species (ion, radical, closed-shell) being computed. This work provides a relatively simple and unambiguous approach that can be used to estimate the thermochemical parameters needed to build detailed ab initio kinetic models of systems in aqueous solution. Technical challenges that limit the accuracy of the estimates are

  20. Densification of ∼5 nm-thick SiO2 layers by nitric acid oxidation

    Science.gov (United States)

    Choi, Jaeyoung; Joo, Soyeong; Park, Tae Joo; Kim, Woo-Byoung

    2017-08-01

    Low-temperature nitric acid (HNO3) oxidation of Si (NAOS) has been used to improve the interface and electrical properties of ∼5 nm-thick SiO2/Si layers produced by plasma-enhanced chemical vapor deposition (PECVD). Investigations of the physical properties and electrical characteristics of these thin films revealed that although their thickness is not changed by NAOS, the leakage current density at a gate bias voltage of -1 V decreases by about two orders of magnitude from 1.868 × 10-5 A/cm2. This leakage current density was further reduced by post-metallization annealing (PMA) at 250 °C for 10 min in a 5 vol.% hydrogen atmosphere, eventually reaching a level (5.2 × 10-8 A/cm2) approximately three orders of magnitude less than the as-grown SiO2 layer. This improvement is attributed to a decrease in the concentration of suboxide species (Si1+, Si2+ and Si3+) in the SiO2/Si interface, as well as a decrease in the equilibrium density of defect sites (Nd) and fixed charge density (Nf). The barrier height (Vt) generated by a Poole-Frenkel mechanism also increased from 0.205 to 0.371 eV after NAOS and PMA. The decrease in leakage current density is therefore attributed to a densification of the SiO2 layer in combination with the removal of OH species and increase in interfacial properties at the SiO2/Si interface.

  1. Chronic exposure to ozone and nitric acid vapor results in increased levels of rat pulmonary putrescine

    Energy Technology Data Exchange (ETDEWEB)

    Sindhu, R.K.; Kikkawa, Yutaka [Department of Pathology, College of Medicine, University of California at Irvine, Irvine (United States); Mautz, W.J. [Department of Community and Environmental Medicine, University of California at Irvine, Irvine, CA (United States)

    1998-06-01

    In the past decade, there has been growing public concern for the human health effects of exposure to environmental pollutants. Ozone (O{sub 3}) is one of the most reactive components of photochemical air pollution. Despite extensive investigations by many laboratories on the functional, biochemical, and cellular effects of O{sub 3} exposure in humans, animals, and in vitro systems, questions remain concerning the potential adverse effects to human health represented by chronic near-ambient exposure to this environmental pollutant. In the present investigation, the influence of inhalation of O{sub 3} and nitric acid (HNO{sub 3}) vapor on polyamine levels was examined in rat lungs. Male F344/N rats were exposed nose-only to 0.15 ppm O{sub 3} and 50 {mu}g/m{sup 3} HNO{sub 3} vapor alone and in combination for 4 hours/day, 3 days/week for a total of 40 weeks. At this time the animals were sacrificed and their lungs were examined for polyamine contents. Exposure to O{sub 3} and O{sub 3} plus HNO{sub 3} vapor caused a significant increase in the putrescine content of the lung compared to the air-exposed controls (P < 0.05). The concentrations of pulmonary spermidine and spermine were not significantly increased by exposure to either O{sub 3} or HNO{sub 3} vapor alone or in combination compared to the air-exposed controls. The role of polyamines in repair and anti-inflammatory processes has been discussed. (orig.) (orig.) With 1 fig., 1 tab., 30 refs.

  2. Influence of Fe loadings on desulfurization performance of activated carbon treated by nitric acid.

    Science.gov (United States)

    Guo, Jia-Xiu; Shu, Song; Liu, Xiao-Li; Wang, Xue-Jiao; Yin, Hua-Qiang; Chu, Ying-Hao

    2017-02-01

    A series of Fe supported on activated carbon treated by nitric acid are prepared by incipient wetness impregnation with ultrasonic assistance and characterized by N2 adsorption-desorption, X-ray diffraction, Fourier transform infrared spectrum and X-ray photoelectron spectroscopy. It has shown that Fe loadings significantly influence the desulfurization activity. Fe/NAC5 exhibits an excellent removal ability of SO2, corresponding to breakthrough sulfur capacity of 323 mg/g. With the increasing Fe loadings, the generated Fe3O4 and Fe2SiO4 increase, but Fe2(SO4)3 is observed after desulfurization. Fe/NAC1 has a Brunauer-Emmett-Teller (BET) surface area of 925 m(2)/g with micropore surface area of 843 m(2)/g and total pore volume of 0.562 cm(3)/g including a micropore volume of 0.300 cm(3)/g. With the increasing Fe loadings, BET surface area and micropore volume decrease, and those of Fe/NAC10 decrease to 706 m(2)/g and 0.249 cm(3)/g. The Fe loadings influence the pore-size distribution, and SO2 adsorption mainly reacts in micropores at about 0.70 nm. C=O and C-O are observed for all samples before SO2 removal. After desulfurization, the C-O stretching is still detected, but the C=O stretching vibration of carbonyl groups disappears. The stretching of S-O or S=O in sulfate is observed at 592 cm(-1) for the used sample, proving that the existence of [Formula: see text].

  3. Intergranular corrosion testing of austenitic stainless steels in nitric acid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Whillock, G.O.H.; Dunnett, B. F. [British Nuclear Fuels plc, BNFL, B170, Sellafield, Seascale, Cumbria CA20 1PG (United Kingdom)

    2004-07-01

    In hot strong nitric acid solutions, stainless steels exhibit intergranular corrosion. Corrosion rates are often measured from immersion testing of specimens manufactured from the relevant material (e.g. plate or pipe). The corrosion rates, measured from weight loss, are found to increase with time prior to reaching steady state, which can take thousands of hours to achieve. The apparent increase in corrosion rate as a function of time was found to be an artefact due to the surface area of the specimen's being used in the corrosion rate calculations, rather than that of the true area undergoing active corrosion i.e. the grain boundaries. The steady state corrosion rate coincided with the onset of stable grain dropping, where the use of the surface area of the specimen to convert the weight loss measurements to corrosion rates was found to be appropriate. This was confirmed by sectioning of the specimens and measuring the penetration depths. The rate of penetration was found to be independent of time and no induction period was observed. A method was developed to shorten considerably the testing time to reach the steady state corrosion rate by use of a pre-treatment that induces grain dropping. The long-term corrosion rates from specimens which were pre-treated was similar to that achieved after prolonged testing of untreated (i.e. initially ground) specimens. The presence of cut surfaces is generally unavoidable in the simple immersion testing of specimens in test solutions. However, inaccuracy in the results may occur as the measured corrosion rate is often influenced by the orientation of the microstructure, the highest rates typically being observed on the cut surfaces. Two methods are presented which allow deconvolution of the corrosion rates from immersion testing of specimens containing cut surfaces, thus allowing reliable prediction of the long-term corrosion rate of plate surfaces. (authors)

  4. Laboratory evaluation of the effect of nitric acid uptake on frost point hygrometer performance

    Directory of Open Access Journals (Sweden)

    T. Thornberry

    2010-08-01

    Full Text Available Chilled mirror hygrometers (CMH are widely used to measure water vapour in the troposphere and lower stratosphere from balloon-borne sondes. Systematic discrepancies among in situ water vapour instruments have been observed at low water vapour mixing ratios (<5 ppm in the upper troposphere and lower stratosphere (UT/LS. Understanding the source of the measurement discrepancies is important for a more accurate and reliable determination of water vapour abundance in this region. We have conducted a laboratory study to investigate the potential interference of gas-phase nitric acid (HNO3 with the measurement of frost point temperature, and consequently the water vapour mixing ratio, determined by CMH under conditions representative of operation in the UT/LS. No detectable interference in the measured frost point temperature was found for HNO3 mixing ratios of up to 4 ppb for exposure times up to 150 min. HNO3 was observed to co-condense on the mirror frost, with the adsorbed mass increasing linearly with time at constant exposure levels. Over the duration of a typical balloon sonde ascent (90–120 min, the maximum accumulated HNO3 amounts were comparable to monolayer coverage of the geometric mirror surface area, which corresponds to only a small fraction of the actual frost layer surface area. This small amount of co-condensed HNO3 is consistent with the observed lack of HNO3 interference in the frost point measurement because the CMH utilizes significant reductions (>10% in surface reflectivity by the condensate to determine H2O.

  5. Laboratory evaluation of the effect of nitric acid uptake on frost point hygrometer performance

    Directory of Open Access Journals (Sweden)

    T. Thornberry

    2011-02-01

    Full Text Available Chilled mirror hygrometers (CMH are widely used to measure water vapour in the troposphere and lower stratosphere from balloon-borne sondes. Systematic discrepancies among in situ water vapour instruments have been observed at low water vapour mixing ratios (<5 ppm in the upper troposphere and lower stratosphere (UT/LS. Understanding the source of the measurement discrepancies is important for a more accurate and reliable determination of water vapour abundance in this region. We have conducted a laboratory study to investigate the potential interference of gas-phase nitric acid (HNO3 with the measurement of frost point temperature, and consequently the water vapour mixing ratio, determined by CMH under conditions representative of operation in the UT/LS. No detectable interference in the measured frost point temperature was found for HNO3 mixing ratios of up to 4 ppb for exposure times up to 150 min. HNO3 was observed to co-condense on the mirror frost, with the adsorbed mass increasing linearly with time at constant exposure levels. Over the duration of a typical balloon sonde ascent (90–120 min, the maximum accumulated HNO3 amounts were comparable to monolayer coverage of the geometric mirror surface area, which corresponds to only a small fraction of the actual frost layer surface area. This small amount of co-condensed HNO3 is consistent with the observed lack of HNO3 interference in the frost point measurement because the CMH utilizes significant reductions (>10% in surface reflectivity by the condensate to determine H2O.

  6. Mutagenicity of bitumen and asphalt fumes.

    Science.gov (United States)

    Heikkilä, P R; Väänänen, V; Hämeilä, M; Linnainmaa, K

    2003-08-01

    The mutagenicity of asphalt fumes was tested with the Salmonella bioassays. The aim was to investigate if recycled additives modify the genotoxicity of emissions. Recycling of old asphalt is increasing, and we studied also the mutagenicity of emissions sampled during the re-use of asphalt. The composition of vapours and fumes were analysed by gas chromatography and by liquid chromatography. Bitumens containing coal fly ash (CFA) or waste plastics were heated to the paving temperatures in the laboratory. In the field, bitumen fumes were collected during paving of stone mastic asphalts (lime or CFA as a filler), remixing of stone mastic asphalt (lime or CFA as a filler), and of asphalt concrete. All the lab-generated vapour fractions were non-mutagenic. The particulate fractions were mutagenic with TA98 in the presence of the S9 activation. In addition, the lab-fumes from bitumen containing waste plastics were positive with both strains without S9. Only particulate fractions sampled in the field were tested. They were mutagenic with and without metabolic activation with both strains. The mutagenic potency of the field samples was higher than that of the lab-generated fumes without S9, and the remixing fumes were more mutagenic than the normal paving and lab-generated fumes with S9. The use of inorganic additive, CFA, did not change the mutagenicity of the fumes, whereas the organic additive, waste plastics, increased the mutagenicity of the laboratory emissions significantly.

  7. The Significance of Lewis Acid Sites for the Selective Catalytic Reduction of Nitric Oxide on Vanadium-Based Catalysts.

    Science.gov (United States)

    Marberger, Adrian; Ferri, Davide; Elsener, Martin; Kröcher, Oliver

    2016-09-19

    The long debated reaction mechanisms of the selective catalytic reduction (SCR) of nitric oxide with ammonia (NH3 ) on vanadium-based catalysts rely on the involvement of Brønsted or Lewis acid sites. This issue has been clearly elucidated using a combination of transient perturbations of the catalyst environment with operando time-resolved spectroscopy to obtain unique molecular level insights. Nitric oxide reacts predominantly with NH3 coordinated to Lewis sites on vanadia on tungsta-titania (V2 O5 -WO3 -TiO2 ), while Brønsted sites are not involved in the catalytic cycle. The Lewis site is a mono-oxo vanadyl group that reduces only in the presence of both nitric oxide and NH3 . We were also able to verify the formation of the nitrosamide (NH2 NO) intermediate, which forms in tandem with vanadium reduction, and thus the entire mechanism of SCR. Our experimental approach, demonstrated in the specific case of SCR, promises to progress the understanding of chemical reactions of technological relevance.

  8. INVESTIGATION OF THE OPTIMUM DISSOLUTION TEMPERATURES OF PHOSPHORUS IN SULPHURIC, NITRIC AND OXALIC ACID SOLUTIONS DURING LEACHING OF IRON OXIDE ORE

    Directory of Open Access Journals (Sweden)

    C. I. NWOYE

    2009-12-01

    Full Text Available Studies were carried out to determine the optimum dissolution temperatures of phosphorus in oxalic, nitric and sulphuric acid solutions during leaching of iron oxide ore. Phosphorus dissolution rates and dissolution per unit rise in temperature were determined and compared to ascertain the preferred acid in terms of effective dephosphorization of iron oxide ore using leaching process. The results of the investigation show that the optimum dissolution temperatures of phosphorus in these acids were found to be 45, 55 and 70ºC respectively. Phosphorus dissolutions per unit rise in temperature in these acid solutions during the increasing and decreasing stage of dissolution were 9.4 and -3.07 mg/kg/ºC 2.88 and -4.7 mg/kg/ºC and also 2.16 and -7.95 mg/kg/ºC respectively. Phosphorus dissolution rates in these acid solutions during the increasing and decreasing stage of dissolution were also determined as 0.67 and -0.13 mg/kg/s, 0.14 and -0.19 mg/kg/s and also 0.1 and 0.44 mg/kg/s for oxalic, nitric and sulphuric acid solutions respectively. This confers to oxalic acid a better dissolution power on phosphorus over nitric and sulphuric acid, followed by nitric acid.

  9. A laboratory study of the heterogeneous reaction of nitric acid on calcium carbonate particles

    Science.gov (United States)

    Goodman, A. L.; Underwood, G. M.; Grassian, V. H.

    2000-12-01

    It has been postulated that the reaction of nitric acid with calcium carbonate, namely, CaCO3(s) + 2HNO3(g) → Ca(NO3)2(s) + CO2(g) + H2O(g), plays an important role in the atmosphere. In this study, transmission FTIR spectroscopy, diffuse reflectance UV-visible spectroscopy, transmission electron microscopy and a Knudsen cell reactor coupled to a quadrupole mass spectrometer have been used to investigate the heterogeneous reactivity of HNO3 on CaCO3 at 295 K as a function of relative humidity. Transmission FTIR spectroscopy was used to probe both gas-phase and adsorbed products and showed that the reaction of HNO3 and CaCO3 is limited to the surface of the CaCO3 particle in the absence of adsorbed water. However, in the presence of water vapor, the reaction is greatly enhanced and is not limited to the surface of the particle producing both solid calcium nitrate and gaseous carbon dioxide. The enhanced reactivity of the particles is attributed to the presence of a layer of adsorbed water on the particle surface. The amount of adsorbed water on the particle surface is strongly dependent on the extent of the reaction. This can be understood in terms of the increased hydrophilicity of calcium nitrate as compared to calcium carbonate. Data from experiments using a mass-calibrated Knudsen cell reactor showed the stoichiometry for the reaction determined from gas-phase species deviated from that expected from the balanced equation. Water adsorption on the particle surface and gases dissolved into the water layer appear to be the cause of this discrepancy. The measured uptake coefficient accounting for the BET area of the sample is determined to be 2.5±0.1×10-4 for HNO3 on CaCO3 under dry conditions and is found to increase in the presence of water vapor. Atmospheric implications of the results presented here are discussed.

  10. Nitric acid in the stratosphere based on Odin observations from 2001 to 2009 – Part 1: A global climatology

    Directory of Open Access Journals (Sweden)

    J. Urban

    2009-09-01

    Full Text Available The Sub-Millimetre Radiometer (SMR on board the Odin satellite, launched in February 2001, observes thermal emissions of stratospheric nitric acid (HNO3 originating from the Earth limb in a band centred at 544.6 GHz. Height-resolved measurements of the global distribution of nitric acid in the stratosphere were performed approximately on two observation days per week. An HNO3 climatology based on more than 7 years of observations from August 2001 to April 2009 covering the vertical range between typically ~19 and 45 km (~1.5–60 hPa or ~500–1800 K in terms of potential temperature was created. The study highlights the spatial and seasonal variation of nitric acid in the stratosphere, characterised by a pronounced seasonal cycle at middle and high latitudes with maxima during late fall and minima during spring, strong denitrification in the lower stratosphere of the Antarctic polar vortex during winter (the irreversible removal of NOy by the sedimentation of cloud particles containing HNO3, as well as large quantities of HNO3 formed every winter at high-latitudes in the middle and upper stratosphere. A strong inter-annual variability is observed in particular at high latitudes. A comparison with a stratospheric HNO3 climatology, based on over 7 years of UARS/MLS (Upper Atmosphere Research Satellite/Microwave Limb Sounder measurements from the 1990s, shows good consistency and agreement of the main morphological features in the potential temperature range ~465 to ~960 K, if the different characteristics of the data sets such as the better altitude resolution of Odin/SMR as well as the slightly different altitude ranges are considered. Odin/SMR reaches higher up and UARS/MLS lower down in the stratosphere. An overview from 1991 to 2009 of stratospheric nitric acid is provided (with a short gap between 1998 and 2001, if the global measurements of both experiments are taken together.

  11. Influence of gas-particle partitioning on ammonia and nitric acid fluxes above a deciduous forest in the Midwestern USA

    DEFF Research Database (Denmark)

    Hansen, Kristina; Sørensen, Lise Lotte; Hornsby, Karen E.

    Quantifying the atmosphere-biosphere exchange of reactive nitrogen gasses (including ammonia (NH3) and nitric acid (HNO3)) is crucial to assessing the impact of anthropogenic activities on natural and semi-natural ecosystems. However, measuring the deposition of reactive nitrogen is challenging due...... are measured above the deciduous forest, Morgan Monroe State Forest (MMSF) in south-central Indiana (39°53’N, 86°25’W) during a field campaign. Two relaxed eddy accumulation (REA) systems are used to measure fluxes and concentrations of NH3 and HNO3 at 44 m. The NH3 REA system operates based on wet effluent...

  12. Effect of Nitric Acid on the Low Fluorescing Performance of Drilling Fluid Lubricant Based Animal and Vegetable Oils

    Directory of Open Access Journals (Sweden)

    Feng-shan Zhou

    2013-01-01

    Full Text Available After synthesis of mixed fatty acid triethanolamine ester surfactant based on animal and vegetable mixed oils, the reaction solution was added into 4% (wt/wt liquid nitric acid or 9% (wt/wt solid nitric acid as eliminating fluorescent agent continuing to react from 1 to 2 hours. The low fluorescence lubricant named E167 for drilling fluid was prepared, in which maximum fluorescence intensity (Fmax was less than 10 in three-dimensional fluorescence spectra of excitation wavelength range. When the E167 was added into fresh water based drilling fluid at the dosage of 0.5% (wt/wt, the sticking coefficient reduced rate (ΔKf is 78% and the extreme pressure (E-P friction coefficient reduced rate (Δf is 79%. In the case of 4% brine mud with 0.5% (wt/wt E167 in it, the ΔKf and Δf are 75% and 62%, respectively. After the hot rolling ageing test 180°C × 16 h with the E167 was added into fresh water based drilling fluid at the dosage of 1% (wt/wt, the ΔKf and Δf are greater than 70%, which shows a much better lubrication properties of strong resistance to high temperature. The fresh water based drilling fluid which contains 1% (wt/wt E167 is almost nonfoaming even after hot rolling ageing 120°C × 16 h.

  13. Comparative analysis of the effect of pretreating aspen wood with aqueous and aqueous-organic solutions of sulfuric and nitric acid on its reactivity during enzymatic hydrolysis

    DEFF Research Database (Denmark)

    Dotsenko, Gleb; Osipov, D. O.; Zorov, I. N.;

    2016-01-01

    The effect of aspen wood pretreatment methods with the use of both aqueous solutions of sulfuric and nitric acids and aqueous-organic solutions (ethanol, butanol) of sulfuric acid (organosolv) on the limiting degree of conversion of this type of raw material into simple sugars during enzymatic...... of ground wood by 300–400%, compared to the initial raw material. Pretreatment with a 4.8% aqueous solution of nitric acid (125°C, 1.8 MPa, 10 min) is shown to be most effective, as it increases the reactivity of the ground aspen wood by more than 500%....

  14. [Effects of exogenous nitric oxide on physiological characteristics of longan (Dimocarpus longana) seedlings under acid rain stress].

    Science.gov (United States)

    Liu, Jian-fu; Wang, Ming-yuan; Yang, Chen; Zhu, Ai-jun

    2013-08-01

    This paper studied the effects of exogenous nitric oxide donor sodium nitroprusside (SNP) on the chlorophyll content, antioxidant enzyme activities, and osmotic regulation substances of longan (Dimocarpus longana 'Fuyan') seedlings under acid rain (pH 3.0) stress. Under the acid rain stress, the seedling leaf superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities and chlorophyll, soluble protein and soluble sugar contents decreased obviously, while the leaf malondialdedyde content had a remarkable increase, suggesting the toxic effect of the acid rain on the seedlings. Exogenous nitric oxide had dual nature on the physiological characteristics of longan seedlings under acid rain stress. Applying 0.1-0.5 mmol x L(-1) of SNP improved the SOD, POD and CAT activities and the chlorophyll, soluble protein and soluble sugar contents significantly, and decreased the malondialdedyde content. Low concentrations SNP reduced the oxidative damage caused by the acid rain stress, and 0.5 mmol x L(-1) of SNP had the best effect. Under the application of 0.5 mmol x L(-1) of SNP, the total chlorophyll, soluble protein, and soluble sugar contents and the SOD, POD and CAT activities increased by 76.0%, 107.0%, 216.1%, 150. 0%, 350.9% and 97.1%, respectively, and the malondialdedyde content decreased by 46.4%. It was suggested that low concentration (0.1-0.5 mmol x L(-1)) SNP could alleviate the toxic effect of acid rain stress on longan seedlings via activating the leaf antioxidant enzyme activities and reducing oxidative stress, while high concentration SNP (1.0 mmol x L(-1)) lowered the mitigation effect.

  15. Role of calcium signaling in the activation of mitochondrial nitric oxide synthase and citric acid cycle.

    Science.gov (United States)

    Traaseth, Nathaniel; Elfering, Sarah; Solien, Joseph; Haynes, Virginia; Giulivi, Cecilia

    2004-07-23

    An apparent discrepancy arises about the role of calcium on the rates of oxygen consumption by mitochondria: mitochondrial calcium increases the rate of oxygen consumption because of the activation of calcium-activated dehydrogenases, and by activating mitochondrial nitric oxide synthase (mtNOS), decreases the rates of oxygen consumption because nitric oxide is a competitive inhibitor of cytochrome oxidase. To this end, the rates of oxygen consumption and nitric oxide production were followed in isolated rat liver mitochondria in the presence of either L-Arg (to sustain a mtNOS activity) or N(G)-monomethyl-L-Arg (NMMA, a competitive inhibitor of mtNOS) under State 3 conditions. In the presence of NMMA, the rates of State 3 oxygen consumption exhibited a K(0.5) of 0.16 microM intramitochondrial free calcium, agreeing with those required for the activation of the Krebs cycle. By plotting the difference between the rates of oxygen consumption in State 3 with L-Arg and with NMMA at various calcium concentrations, a K(0.5) of 1.2 microM intramitochondrial free calcium was obtained, similar to the K(0.5) (0.9 microM) of the dependence of the rate of nitric oxide production on calcium concentrations. The activation of dehydrogenases, followed by the activation of mtNOS, would lead to the modulation of the Krebs cycle activity by the modulation of nitric oxide on the respiratory rates. This would ensue in changes in the NADH/NAD and ATP/ADP ratios, which would influence the rate of the cycle and the oxygen diffusion.

  16. DISSOLUTION OF PLUTONIUM METAL IN 8-10 M NITRIC ACID

    Energy Technology Data Exchange (ETDEWEB)

    Rudisill, T.; Pierce, R.

    2012-02-21

    The H-Canyon facility will be used to dissolve Pu metal for subsequent purification and conversion to plutonium dioxide (PuO{sub 2}) using Phase II of HB-Line. To support the new mission, the development of a Pu metal dissolution flowsheet which utilizes concentrated (8-10 M) nitric acid (HNO{sub 3}) solutions containing potassium fluoride (KF) is required. Dissolution of Pu metal in concentrated HNO{sub 3} is desired to eliminate the need to adjust the solution acidity prior to purification by anion exchange. The preferred flowsheet would use 8-10 M HNO{sub 3}, 0.015-0.07 M KF, and 0.5-1.0 g/L Gd to dissolve the Pu up to 6.75 g/L. An alternate flowsheet would use 8-10 M HNO{sub 3}, 0.1-0.2 M KF, and 1-2 g/L B to dissolve the Pu. The targeted average Pu metal dissolution rate is 20 mg/min-cm{sup 2}, which is sufficient to dissolve a 'standard' 2250-g Pu metal button in 24 h. Plutonium metal dissolution rate measurements showed that if Gd is used as the nuclear poison, the optimum dissolution conditions occur in 10 M HNO{sub 3}, 0.04-0.05 M KF, and 0.5-1.0 g/L Gd at 112 to 116 C (boiling). These conditions will result in an estimated Pu metal dissolution rate of {approx}11-15 mg/min-cm{sup 2} and will result in dissolution times of 36-48 h for standard buttons. The recommended minimum and maximum KF concentrations are 0.03 M and 0.07 M, respectively. The maximum KF concentration is dictated by a potential room-temperature Pu-Gd-F precipitation issue at low Pu concentrations. The purpose of the experimental work described in this report was two-fold. Initially a series of screening experiments was performed to measure the dissolution rate of Pu metal as functions of the HNO{sub 3}, KF, and Gd or B concentrations. The objective of the screening tests was to propose optimized conditions for subsequent flowsheet demonstration tests. Based on the rate measurements, this study found that optimal dissolution conditions in solutions containing 0.5-1.0 g/L Gd

  17. DISSOLUTION OF PLUTONIUM METAL IN 8-10 M NITRIC ACID

    Energy Technology Data Exchange (ETDEWEB)

    Rudisill, T.; Pierce, R.

    2012-02-21

    The H-Canyon facility will be used to dissolve Pu metal for subsequent purification and conversion to plutonium dioxide (PuO{sub 2}) using Phase II of HB-Line. To support the new mission, the development of a Pu metal dissolution flowsheet which utilizes concentrated (8-10 M) nitric acid (HNO{sub 3}) solutions containing potassium fluoride (KF) is required. Dissolution of Pu metal in concentrated HNO{sub 3} is desired to eliminate the need to adjust the solution acidity prior to purification by anion exchange. The preferred flowsheet would use 8-10 M HNO{sub 3}, 0.015-0.07 M KF, and 0.5-1.0 g/L Gd to dissolve the Pu up to 6.75 g/L. An alternate flowsheet would use 8-10 M HNO{sub 3}, 0.1-0.2 M KF, and 1-2 g/L B to dissolve the Pu. The targeted average Pu metal dissolution rate is 20 mg/min-cm{sup 2}, which is sufficient to dissolve a 'standard' 2250-g Pu metal button in 24 h. Plutonium metal dissolution rate measurements showed that if Gd is used as the nuclear poison, the optimum dissolution conditions occur in 10 M HNO{sub 3}, 0.04-0.05 M KF, and 0.5-1.0 g/L Gd at 112 to 116 C (boiling). These conditions will result in an estimated Pu metal dissolution rate of {approx}11-15 mg/min-cm{sup 2} and will result in dissolution times of 36-48 h for standard buttons. The recommended minimum and maximum KF concentrations are 0.03 M and 0.07 M, respectively. The maximum KF concentration is dictated by a potential room-temperature Pu-Gd-F precipitation issue at low Pu concentrations. The purpose of the experimental work described in this report was two-fold. Initially a series of screening experiments was performed to measure the dissolution rate of Pu metal as functions of the HNO{sub 3}, KF, and Gd or B concentrations. The objective of the screening tests was to propose optimized conditions for subsequent flowsheet demonstration tests. Based on the rate measurements, this study found that optimal dissolution conditions in solutions containing 0.5-1.0 g/L Gd

  18. Uric acid attenuates nitric oxide production by decreasing the interaction between endothelial nitric oxide synthase and calmodulin in human umbilical vein endothelial cells: a mechanism for uric acid-induced cardiovascular disease development.

    Science.gov (United States)

    Park, Jung-Hyun; Jin, Yoon Mi; Hwang, Soojin; Cho, Du-Hyong; Kang, Duk-Hee; Jo, Inho

    2013-08-01

    The elevated level of uric acid in the body is associated with increased risk of cardiovascular diseases, which is mediated by endothelial dysfunction. However, its underlying mechanism is not fully understood, although dysregulation of endothelial nitric oxide (NO) production is likely to be involved. Using human umbilical vascular endothelial cells (HUVEC), we explored the molecular mechanism of uric acid on endothelial NO synthase (eNOS) activity and NO production. Although high dose of uric acid (12mg/dl for 24h treatment) significantly decreased eNOS activity and NO production, it did not alter eNOS expression and phosphorylations at eNOS-Ser(1177), eNOS-Thr(495) and eNOS-Ser(114). Under this condition, we also found no alterations in the dimerization and acetylation of eNOS, compared with the control. Furthermore, uric acid did not change the activity of arginase II, an enzyme degrading l-arginine, a substrate of eNOS, and intracellular level of calcium, a cofactor for eNOS activation. We also found that uric acid did not alter xanthine oxidase activity, suggesting no involvement of xanthine oxidase-derived O2(-) production in the observed inhibitory effects. In vitro and in cell coimmunoprecipitation studies, however, revealed that uric acid significantly decreased the interaction between eNOS and calmodulin (CaM), an eNOS activator, although it did not change the intracellular CaM level. Like in HUVEC, uric acid also decreased eNOS-CaM interaction in bovine aortic EC. Finally, uric acid attenuated ionomycin-induced increase in the interaction between eNOS and CaM. This study suggests firstly that uric acid decreased eNOS activity and NO production through reducing the binding between eNOS and CaM in EC. Our result may provide molecular mechanism by which uric acid induces endothelial dysfunction.

  19. Effect of plasticizer and fumed silica on ionic conductivity behaviour of proton conducting polymer electrolytes containing HPF6

    Indian Academy of Sciences (India)

    Jitender Paul Sharma; S S Sekhon

    2013-08-01

    The effect of addition of propylene carbonate (PC) and nano-sized fumed silica on the ionic conductivity behaviour of proton conducting polymer electrolytes containing different concentrations of hexafluorophosphoric acid (HPF6) in polyethylene oxide (PEO) has been studied. The addition of PC results in an increase in ionic conductivity, whereas the addition of nano-sized fumed silica improves mechanical strength of electrolytes along with a small increase in ionic conductivity. It was observed that the simultaneous addition of PC and fumed silica results in electrolytes with optimum value of ionic conductivity and other properties.

  20. Ozone, nitric acid, and ammonia air pollution is unhealthy for people and ecosystems in southern Sierra Nevada, California

    Energy Technology Data Exchange (ETDEWEB)

    Cisneros, Ricardo, E-mail: rcisneros@fs.fed.u [USDA Forest Service, Pacific Southwest Region, 1600 Tollhouse Road, Clovis, CA 93611 (United States); Bytnerowicz, Andrzej, E-mail: abytnerowicz@fs.fed.u [USDA Forest Service, Pacific Southwest Research Station, 4955 Canyon Crest Dr., Riverside, CA 92507 (United States); Schweizer, Donald, E-mail: dschweizer@fs.fed.u [USDA Forest Service, Pacific Southwest Region, 1600 Tollhouse Road, Clovis, CA 93611 (United States); Zhong, Sharon, E-mail: zhongs@msu.ed [Department of Geography, Michigan State University, 116 Geography Building East, Lansing, MI 48824-1117 (United States); Traina, Samuel, E-mail: straina@ucmerced.ed [Environmental Systems Graduate Group, University of California Merced, 5200 North Lake Road, Merced, CA 95343 (United States); Bennett, Deborah H., E-mail: dhbennett@ucdavis.ed [Department of Public Health Sciences, University of California Davis, One Shields Avenue, TB 169 Davis, CA 95616 (United States)

    2010-10-15

    Two-week average concentrations of ozone (O{sub 3}), nitric acid vapor (HNO{sub 3}) and ammonia (NH{sub 3}) were measured with passive samplers during the 2002 summer season across the central Sierra Nevada Mountains, California, along the San Joaquin River drainage. Elevated concentrations of the pollutants were determined with seasonal means for individual sites ranging between 62 and 88 ppb for O{sub 3}, 1.0-3.8 {mu}g m{sup -3} for HNO{sub 3}, and 2.6-5.2 {mu}g m{sup -3} for NH{sub 3}. Calculated O{sub 3} exposure indices were very high, reaching SUM00-191 ppm h, SUM60-151 ppm h, and W126-124 ppm h. Calculated nitrogen (N) dry deposition ranged from 1.4 to 15 kg N ha{sup -1} for maximum values, and 0.4-8 kg N ha{sup -1} for minimum values; potentially exceeding Critical Loads (CL) for nutritional N. The U.S., California, and European 8 h O{sub 3} human health standards were exceeded during 104, 108, and 114 days respectively, indicating high risk to humans from ambient O{sub 3}. - Ozone concentrations remained unchanged while those of nitric acid vapor and ammonia decreased along the river drainage crossing the Sierra Nevada Mountains.

  1. Solvent extraction of uranium(VI) and thorium(IV) in nitric acid solution by N,N,N‘,N’—tetrabutyladipicamide

    Institute of Scientific and Technical Information of China (English)

    WangYou-Shao; BaoBo-Rong; 等

    1997-01-01

    N,N,N'N'-tetrabutyladipicamide(TBAA) has been synthesized,and applied to the extraction of U(VI) and Th(IV) from nitric acid solutions in a diluent composed of 0.50 volume fraction 1,2,4-trimethyl benzene (TMA) and 0.50 volume fraction kerosene(OK),The effects of the aueous nitric acid concentration,extractant concentration,slating-out agent (LiNO3) and temperature on extraction ability of TBAA for U(VI) and Th(IV) have been studied.Back Extraction of U(VI) and Th (IV) from organic phases were performed by dilute nitric acid.The compositions of extracted complexes,equilibrium constants and enthalpies of extraction reactions have also been estimated.The IR spectra of extraction of U(VI) and Th(IV) have been studied.

  2. Design for a Miniature Portable Fume Hood.

    Science.gov (United States)

    Bailey, Ronald A.; Wait, Samuel C., Jr.

    1999-01-01

    Describes the design of undergraduate chemical laboratory fume hoods. Proves that folding the sides and top permit the hood and its duct hose to be stored in a standard 18-inch-wide laboratory cabinet. (WRM)

  3. Plasma levels of nitric oxide related amino acids in demented subjects with Down syndrome are related to neopterin concentrations.

    Science.gov (United States)

    Coppus, A M W; Fekkes, D; Verhoeven, W M A; Tuinier, S; van Duijn, C M

    2010-03-01

    Subjects with Down syndrome (DS) have abnormalities in virtually all aspects of the immune system and almost all will be affected with Alzheimer's disease (AD). It is thought that nitric oxide (NO) is involved in the pathophysiology of AD. In the present study, including a total of 401 elderly DS subjects, the spectrum of plasma amino acids and neopterin was investigated and related to development of AD. Concentrations of nearly all amino acids in DS subjects differed significantly from those of healthy controls. Neopterin was increased in DS subjects, especially in dementia. The production of NO as reflected by an increased citrulline/arginine ratio (Cit/Arg ratio) was enhanced during development of clinical dementia. Neopterin concentrations correlated to the Cit/Arg ratio only in the group of prevalent demented subjects (rho = 0.48, P = 0.006). The results of this study are suggestive for an increase in oxidative processes in DS subjects with AD.

  4. Influence of Silica Fume on Normal Concrete

    Directory of Open Access Journals (Sweden)

    Debabrata Pradhan

    2013-09-01

    Full Text Available The incorporation of silica fume into the normal concrete is a routine one in the present days to produce the tailor made high strength and high performance concrete. The design parameters are increasing with the incorporation of silica fume in conventional concrete and the mix proportioning is becoming complex. The main objective of this paper has been made to investigate the different mechanical properties like compressive strength, compacting factor, slump of concrete incorporating silica fume. In this present paper 5 (five mix of concrete incorporating silica fume are cast to perform experiments. These experiments were carried out by replacing cement with different percentages of silica fume at a single constant water-cementitious materials ratio keeping other mix design variables constant. The silica fume was replaced by 0%, 5%, 10%, 15% and 20% for water-cementitious materials (w/cm ratio for 0.40. For all mixes compressive strengths were determined at 24 hours, 7 and 28 days for 100 mm and 150 mm cubes. Other properties like compacting factor and slump were also determined for five mixes of concrete.

  5. WOOD COLOR CHANGES BY AMMONIA FUMING

    Directory of Open Access Journals (Sweden)

    Josip Miklečić,

    2012-06-01

    Full Text Available This paper studies the influence of ammonia gas on wood color changes in response to an increasing demand for dark colored wood specimens. The darker wood color in ammonia fuming is accomplished through chemical reactions between ammonia gas and wood compounds. We exposed oak, maple, spruce, and larch wood samples to ammonia gas for 16 days. During fuming, the color changes were studied using CIE L*a*b* parameters. After fuming, the changes in extractives content, tannin, and nitrogen content were analyzed. The chemical changes of wood and residues of wood extractives after fuming were analyzed by FTIR spectroscopy. Oak wood reacted intensively with ammonia gas in a very short time, and the darkening was prominent for all the investigated wood species. It was established that tannin had no major influence on color changes of maple and larch wood in the ammonia-fuming process. The FTIR spectra of fumed wood indicated involvement of carbonyl groups, and the FTIR spectra of wood extractives indicated involvement of carbonyl, aromatic, and alcohol groups in reaction with ammonia gas.

  6. GLYCOLIC-NITRIC ACID FLOWSHEET DEMONSTRATION OF THE DWPF CHEMICAL PROCESSING CELL WITH MATRIX SIMULANTS AND SUPERNATE

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, D.; Stone, M.; Newell, J.; Best, D.

    2012-05-07

    Savannah River Remediation (SRR) is evaluating changes to its current DWPF flowsheet to improve processing cycle times. This will enable the facility to support higher canister production while maximizing waste loading. Higher throughput is needed in the CPC since the installation of the bubblers into the melter has increased melt rate. Due to the significant maintenance required for the DWPF gas chromatographs (GC) and the potential for production of flammable quantities of hydrogen, reducing or eliminating the amount of formic acid used in the CPC is being developed. Earlier work at Savannah River National Laboratory has shown that replacing formic acid with an 80:20 molar blend of glycolic and formic acids has the potential to remove mercury in the SRAT without any significant catalytic hydrogen generation. This report summarizes the research completed to determine the feasibility of processing without formic acid. In earlier development of the glycolic-formic acid flowsheet, one run (GF8) was completed without formic acid. It is of particular interest that mercury was successfully removed in GF8, no formic acid at 125% stoichiometry. Glycolic acid did not show the ability to reduce mercury to elemental mercury in initial screening studies, which is why previous testing focused on using the formic/glycolic blend. The objective of the testing detailed in this document is to determine the viability of the nitric-glycolic acid flowsheet in processing sludge over a wide compositional range as requested by DWPF. This work was performed under the guidance of Task Technical and Quality Assurance Plan (TT and QAP). The details regarding the simulant preparation and analysis have been documented previously.

  7. GLYCOLIC-NITRIC ACID FLOWSHEET DEMONSTRATION OF THE DWPF CHEMICAL PROCESS CELL WITH SLUDGE AND SUPERNATE SIMULANTS

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, D.; Stone, M.; Newell, J.; Best, D.; Zamecnik, J.

    2012-08-28

    Savannah River Remediation (SRR) is evaluating changes to its current Defense Waste Processing Facility (DWPF) flowsheet to improve processing cycle times. This will enable the facility to support higher canister production while maximizing waste loading. Higher throughput is needed in the Chemical Process Cell (CPC) since the installation of the bubblers into the melter has increased melt rate. Due to the significant maintenance required for the DWPF gas chromatographs (GC) and the potential for production of flammable quantities of hydrogen, reducing or eliminating the amount of formic acid used in the CPC is being developed. Earlier work at Savannah River National Laboratory has shown that replacing formic acid with an 80:20 molar blend of glycolic and formic acids has the potential to remove mercury in the SRAT without any significant catalytic hydrogen generation. This report summarizes the research completed to determine the feasibility of processing without formic acid. In earlier development of the glycolic-formic acid flowsheet, one run (GF8) was completed without formic acid. It is of particular interest that mercury was successfully removed in GF8, no formic acid at 125% stoichiometry. Glycolic acid did not show the ability to reduce mercury to elemental mercury in initial screening studies, which is why previous testing focused on using the formic/glycolic blend. The objective of the testing detailed in this document is to determine the viability of the nitric-glycolic acid flowsheet in processing sludge over a wide compositional range as requested by DWPF. This work was performed under the guidance of Task Technical and Quality Assurance Plan (TT&QAP). The details regarding the simulant preparation and analysis have been documented previously.

  8. New Inducible Nitric Oxide Synthase and Cyclooxygenase-2 Inhibitors, Nalidixic Acid Linked to Isatin Schiff Bases via Certain l-Amino Acid Bridges.

    Science.gov (United States)

    Naglah, Ahmed M; Ahmed, Atallah F; Wen, Zhi-Hong; Al-Omar, Mohamed A; Amr, Abd El-Galil E; Kalmouch, Atef

    2016-04-15

    A series of new Schiff bases were synthesized by condensation of isatins with the nalidixic acid-l-amino acid hydrazides. Prior to hydrazide formation, a peptide linkage has been prepared via coupling of nalidixic acid with appropriate l-amino acid methyl esters to yield 3a-c. The chemical structures of the new Schiff bases (5b and 5d-h) were confirmed by means of IR, NMR, mass spectroscopic, and elemental analyses. The anti-inflammatory activity of these Schiff bases was evaluated via measurement of the expressed inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in the lipopolysaccharide (LPS)-stimulated RAW264.7 macrophage cells model. The Schiff bases exhibited significant dual inhibitory effect against the induction of the pro-inflammatory iNOS and COX-2 proteins with variable potencies. However, they strongly down-regulated the iNOS expression to the level of 16.5% ± 7.4%-42.2% ± 19.6% compared to the effect on COX-2 expression (bases, relative to that of COX-2, seems to be a reflection of the combined suppressive effects exerted by their nalidixic acid, isatins (4a-c), and l-amino acid moieties against iNOS expression. These synthesized nalidixic acid-l-amino acid-isatin conjugates can be regarded as a novel class of anti-inflammatory antibacterial agents.

  9. Synergistic Action between Jasmonic Acid and Nitric Oxide in Inducing Matrine Accumulation of Sophora flavescens Suspension Cells

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Secondary metabolites not only play important ecological roles in plants but also are important pharmaceutical and source compounds for derivative synthesis. Production of plant secondary metabolites is believed to be controlled by the endogenous signal network of plants. However, the molecular basis is still largely unknown. Here we show that matrine production of Sophora flavescens Ait. cells treated with low levels of jasmonic acid (JA) and nitric oxide (NO) is significantly increased although treatment with low concentrations of JA or NO alone has no effects on matrine production, showing that JA and NO may act synergistically in triggering matrine production. Moreover, treatment with NO triggers lipoxygenase(LOX) activity and enhances JA levels of the cells, showing that NO may activate the endogenous JA biosynthesis of S.flavescens cells. External application of JA induces nitric oxide synthase-like activities and stimulates NO generation of S. flavescens cells, which suggests that JA may trigger NO generation of the cells. Thus, the results reveal a mutually amplifying reaction between JA and NO in S. flavescens cells. Furthermore, JA and NO inhibitors suppress not only the mutually amplifying reaction between JA and NO but also the synergistic effects of NO and JA on matrine production.Therefore, the data demonstrate that the synergistic action of JA and NO in inducing matrine production might be due to the mutually amplifying reaction between JA and NO in the cells.

  10. Measurement of inorganic arsenic species in rice after nitric acid extraction by HPLC-ICPMS: verification using XANES.

    Science.gov (United States)

    Maher, W; Foster, S; Krikowa, F; Donner, E; Lombi, E

    2013-06-04

    The measurement of As species in rice is normally accomplished by extraction followed by HPLC-ICPMS analysis. This method, however, has not been comprehensively validated by comparing these speciation results with XANES, which does not require sample extraction, due to the challenge of conducting XANES analysis at very low As concentrations. In this study As speciation data using nitric acid extraction/HPLC-ICPMS and XANES are compared to verify the efficacy of using 2% v/v nitric acid extraction and HPLC-ICPMS to measure inorganic As, DMA, and MA in reference rice materials and common rice varieties obtainable in Australia. Total As and As species (As(III), As(V), DMA, and MA) concentrations measured in 8 reference materials were in agreement with published values. XANES analysis was performed on 5 samples having total As concentrations ranging from 0.198 to 0.335 μg g(-1). XANES results gave similar proportions of total As(III), As(V), and DMA to HPLC-ICPMS. XANES was able to distinguish two forms of As(III): As(III) and As(III)GSH. Total As concentrations in rice samples varied from 0.006 to 0.45 μg g(-1) As (n = 47) with a mean ± std of 0.127 ± 0.112 μg g(-1) As with most As present as inorganic species (63 ± 26%). DMA was found in nearly all the rice samples with the majority of samples containing concentrations below 0.05 μg g(-1) As while MA concentrations were negligible (<0.003 μg g(-1) As). Six rice varieties produced in Australia, China, and Spain all had elevated DMA concentrations (0.170-0.399 μg g(-1) As) that were correlated with total As concentrations (r(2) = 0.7518). In conclusion, comparison of As speciation by HPLC-ICPMS and XANES showed that similar As species were detected indicating the appropriateness of using 2% v/v nitric acid for extraction of rice prior to speciation. Common rice varieties obtainable in Australia generally have low As concentrations with most As present as inorganic As.

  11. DISSOLUTION OF PLUTONIUM METAL IN 8-10 M NITRIC ACID

    Energy Technology Data Exchange (ETDEWEB)

    Rudisill, T. S.; Pierce, R. A.

    2012-07-02

    The H-Canyon facility will be used to dissolve Pu metal for subsequent purification and conversion to plutonium dioxide (PuO{sub 2}) using Phase II of HB-Line. To support the new mission, the development of a Pu metal dissolution flowsheet which utilizes concentrated (8-10 M) nitric acid (HNO{sub 3}) solutions containing potassium fluoride (KF) is required. Dissolution of Pu metal in concentrated HNO{sub 3} is desired to eliminate the need to adjust the solution acidity prior to purification by anion exchange. The preferred flowsheet would use 8-10 M HNO{sub 3}, 0.015-0.07 M KF, and 0.5-1.0 g/L Gd to dissolve the Pu up to 6.75 g/L. An alternate flowsheet would use 8-10 M HNO{sub 3}, 0.05-0.2 M KF, and 1-2 g/L B to dissolve the Pu. The targeted average Pu metal dissolution rate is 20 mg/min-cm{sup 2}, which is sufficient to dissolve a “standard” 2250-g Pu metal button in 24 h. Plutonium metal dissolution rate measurements showed that if Gd is used as the nuclear poison, the optimum dissolution conditions occur in 10 M HNO{sub 3}, 0.04-0.05 M KF, and 0.5-1.0 g/L Gd at 112 to 116 °C (boiling). These conditions will result in an estimated Pu metal dissolution rate of ~11-15 mg/min-cm{sup 2} and will result in dissolution times of 36-48 h for standard buttons. The recommended minimum and maximum KF concentrations are 0.03 M and 0.07 M, respectively. The data also indicate that lower KF concentrations would yield dissolution rates for B comparable to those observed with Gd at the same HNO{sub 3} concentration and dissolution temperature. To confirm that the optimal conditions identified by the dissolution rate measurements can be used to dissolve Pu metal up to 6.75 g/L in the presence of representative concentrations of Fe and Gd or B, a series of experiments was performed to demonstrate the flowsheets. In three of the five experiments, the offgas generation rate during the dissolution was measured and samples were analyzed for hydrogen gas (H{sub 2}). The use of

  12. The Meteorology and Chemistry of High Nitric-Acid Episodes at the South Pole

    Science.gov (United States)

    Neff, William; Davis, Douglas

    2016-04-01

    Between 1998 and 2007, a series of field experiments carried out at the South Pole and with aircraft over a wider area revealed a very chemically active boundary layer overlying the east Antarctic ice sheet during the Austral summer. An early discovery was unexpectedly high concentrations of nitric acid (NO) at the South Pole. These were argued to be a result of the UV pholoysis of reactive nitrogen in surface and/or near-surface snow followed by subsequent confinement and non-linear HOx/NOx chemistry within a thin stable atmospheric boundary layer. The concentrations of NO also demonstrated daily, intraseasonal, as well as interannual variability as seen in the four field programs. This paper seeks to elucidate the interplay of large-to-small scale meteorology and chemistry at the South Pole that leads to highly variable NO concentrations and to examine boundary layer depth effects on NO in years when no direct measurements were available, in particular during the latest field program in 2006-2007. The importance of the South Pole is that it, unlike other high-latitude sites, has no diurnal cycle to disturb the evolution of the mostly stable boundary layer and its physics and chemistry. In the spring, as the solar elevation angle increases, nitrate photolysis rates increase. At the same time, the stratospheric vortex warms and with its breakup, the total column ozone increases leading to decreased photolysis rates. In addition, following the formation of the thermal tropopause in early spring, the tropospheric circulation over Antarctica changes dramatically, affecting the transport and dominant source regions for warm air and clouds arriving at the South Pole. The timing of the final warming ranged from early-November to mid-December for the four field experiment years. During the 30 days prior to the final increase in column ozone, as the thermal tropopause forms (~100 hPa), the winds at 300 hPa become bimodal, either along the eastern side of the Weddell Sea

  13. Laboratory Investigation of the Growth and Crystal Structure of Nitric Acid Hydrates by Transmission Electron Microscopy (TEM)

    Science.gov (United States)

    Blake, David F.; Chang, Sherwood (Technical Monitor)

    1994-01-01

    A great deal of recent laboratory work has focussed on the characterization of the nitric acid hydrates, thought to be present in type I Polar Stratospheric Clouds (PSCs). Phase relationships and vapor pressure measurements (1-3) and infrared characterizations (4-5) have been made. However, the observed properties of crystalline solids (composition, melting point, vapor pressure, surface reactivity, thermodynamic stability, extent of solid solution with other components, etc.) are controlled by their crystal structure. The only means of unequivocal structural identification for crystalline solids is diffraction (using electrons, X-rays, neutrons, etc.). Other observed properties of crystalline solids, such as their infrared spectra, their vapor pressure as a function of temperature, etc. yield only indirect information about what phases are present, their relative proportions, or whether they are crystalline or amorphous.

  14. Nitric-phosphoric acid etching effects on the surface chemical composition of CdTe thin film.

    Science.gov (United States)

    Irfan, Irfan; Ding, Huanjun; Xia, Wei; Lin, Hao; Tang, Ching W.; Gao, Yongli

    2009-03-01

    Nitric-phosphoric (NP) acid etching has been regarded as one of the most successful methods for the formation of low resistance back contact with the metal electrode in CdTe based solar cells. We report back surface chemical composition for eight different durations of NP etching of CdTe polycrystalline thin film. We studied the surfaces with x-ray photoemission spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS), inverse photoemission spectroscopy (IEPS) and atomic force microscopy (AFM). Etching dependence on the back surface composition and electronic structure was observed. Valence and conduction band shifts relative to the Fermi level of the system with different etching duration were analyzed. The sample was left in open ambient condition for three weeks and XPS data were obtained again in order to study the difference in surface chemical composition with the pristine CdTe film. Unetched and highly etched part of the sample were sputtered and the depth profile analyzed.

  15. Soft cutting of single-wall carbon nanotubes by low temperature ultrasonication in a mixture of sulfuric and nitric acids

    Science.gov (United States)

    Shuba, M. V.; Paddubskaya, A. G.; Kuzhir, P. P.; Maksimenko, S. A.; Ksenevich, V. K.; Niaura, G.; Seliuta, D.; Kasalynas, I.; Valusis, G.

    2012-12-01

    To decrease single-wall carbon nanotube (SWCNT) lengths to a value of 100-200 nm, aggressive cutting methods, accompanied by a high loss of starting material, are frequently used. We propose a cutting approach based on low temperature intensive ultrasonication in a mixture of sulfuric and nitric acids. The method is nondestructive with a yield close to 100%. It was applied to cut nanotubes produced in three different ways: gas-phase catalysis, chemical vapor deposition, and electric-arc-discharge methods. Raman and Fourier transform infrared spectroscopy were used to demonstrate that the cut carbon nanotubes have a low extent of sidewall degradation and their electronic properties are close to those of the untreated tubes. It was proposed to use the spectral position of the far-infrared absorption peak as a simple criterion for the estimation of SWCNT length distribution in the samples.

  16. Microstructure and Corrosion Behavior of Hf-40 Wt Pct Ti Alloy in Nitric Acid Medium for Reprocessing Applications

    Science.gov (United States)

    Jayaraj, J.; Ravi, K. R.; Mallika, C.; Kamachi Mudali, U.

    2016-09-01

    The Hf-40 wt pct Ti (Hf-Ti) alloy was developed for neutron poison application in the spent nuclear fuel reprocessing plant. The furnace-cooled Hf-Ti sample exhibited the microstructure comprising equiaxed-α, lamellar-α, and feathery-α. The water-quenched Hf-Ti sample confirmed the presence of lath and internally twinned martensite. In comparison to the furnace-cooled sample, low corrosion current density and passivation current density values obtained for the water-quenched Hf-Ti in 6 M HNO3 at 298 K (25 °C) indicated better passivation ability. The martensitic structure exhibited high hardness (660 HV) and negligible corrosion rate in 6 M nitric acid at 298 K (25 °C). X-ray photoelectron spectroscopic (XPS) analysis confirmed that passivation behavior of this alloy was due to the protective passive film composed of TiO2 and HfO2.

  17. Hydrofluoric-nitric-sulphuric-acid surface treatment of tungsten for carbon fibre-reinforced composite hybrids in space applications

    Science.gov (United States)

    Kanerva, M.; Johansson, L.-S.; Campbell, J. M.; Revitzer, H.; Sarlin, E.; Brander, T.; Saarela, O.

    2015-02-01

    Hybrid material systems, such as combinations of tungsten foils and carbon fibre-reinforced plastic (CFRP), are replacing metal alloy concepts in spacecraft enclosures. However, a good adhesion between the tungsten oxide scale and the epoxy resin used is required. Here, the effects of a hydrofluoric-nitric-sulphuric-acid (HFNS) treatment on tungsten oxides and subsequent adhesion to CFRP are analysed using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and fracture testing. The work shows that HFNS treatment results in decreased oxygen content, over 50% thinner tungsten trioxide (WO3) layer and increased nano-roughness on thin tungsten foils. Fracture testing established a 39% increase in the average critical strain for tungsten-CFRP specimens after HFNS treatment was carried out on tungsten. The effect of the oxide scale modification regarding the critical strain energy release rate was ΔGc≈ 8.4 J/m2.

  18. Gene expression profiles of inducible nitric oxide synthase and cytokines in Leishmania major-infected macrophage-like RAW 264.7 cells treated with gallic acid

    NARCIS (Netherlands)

    Radtke, O.A.; Kiderlen, A.F.; Kayser, Oliver; Kolodziej, H

    2004-01-01

    The effects of gallic acid on the gene expressions of inducible nitric oxide synthase (iNOS) and the cytokines interleukin (IL)-1, IL-10, IL-12, IL-18, TNF-alpha, and interferon (IFN)-gamma were investigated by reverse-transcription polymerase chain reaction (RT-PCR). The experiments were performed

  19. Electrical and physicochemical properties of atomic-layer-deposited HfO{sub 2} film on Si substrate with interfacial layer grown by nitric acid oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seung Hyun [Department of Advanced Materials Engineering, Hanyang University, Ansan 15588 (Korea, Republic of); Seok, Tae Jun; Jin, Hyun Soo [Department of Materials Science & Chemical Engineering, Hanyang University, Ansan 15588 (Korea, Republic of); Kim, Woo-Byoung, E-mail: woo7838@dankook.ac.kr [Department of Energy Engineering, Dankook University, Cheonan 330-714 (Korea, Republic of); Park, Tae Joo, E-mail: tjp@hanyang.ac.kr [Department of Advanced Materials Engineering, Hanyang University, Ansan 15588 (Korea, Republic of); Department of Materials Science & Chemical Engineering, Hanyang University, Ansan 15588 (Korea, Republic of)

    2016-03-01

    Graphical abstract: - Highlights: • Ultrathin SiO{sub 2} interfacial layers grown using nitric acid oxidation and O{sub 3} oxidation were adopted at the interface of HfO{sub 2}/Si. • Higher physical density of interfacial layer grown using nitric acid oxidation resulted in the suppressed Si diffusion from substrate into the film. • The interface properties as well as permittivity of the film were improved by adoption of interfacial layer grown using nitric acid oxidation. - Abstract: The ultrathin SiO{sub 2} interfacial layer (IL) was adopted at the interface between atomic-layer-deposited HfO{sub 2} gate dielectric film and a Si substrate, which was grown using nitric acid oxidation (NAO) and O{sub 3} oxidation (OZO) prior to HfO{sub 2} film deposition. X-ray photoelectron spectroscopy result revealed that Si diffusion from the substrate into the film was suppressed for the film with NAO compared to that with OZO, which was attributed to the higher physical density of IL. The electrical measurement using metal–insulator–semiconductor devices showed that the film with NAO exhibited higher effective permittivity and lower densities of fixed charge and slow state at the interface. Furthermore, the leakage current density at an equivalent electrical thickness was lower for the film with NAO than OZO.

  20. Highly active and stable ion-exchanged Fe-Ferrierite catalyst for N2O decomposition under nitric acid tail gas conditions

    NARCIS (Netherlands)

    Melian Cabrera, Ignacio; Mentruit, C; Pieterse, JAZ; van den Brink, RW; Mul, G; Kapteijn, F; Moulijn, JA

    2005-01-01

    This communication reports on the excellent performance and durability of a wet ion-exchanged Fe-Ferrierite catalysts for N2O decomposition under conditions of nitric acid plants, especially in the presence of water (0.5% vol) and at a high space time W/F-0(N2O) = 900 kg(cat) s mol(-1). In contrast

  1. Highly active and stable ion-exchanged Fe–Ferrierite catalyst for N2O decomposition under nitric acid tail gas conditions

    NARCIS (Netherlands)

    Melián-Cabrera, I.; Mentruit, C.; Pieterse, J.A.Z.; Brink, R.W. van den; Mul, G.; Kapteijn, F.; Moulijn, J.A.

    2005-01-01

    This communication reports on the excellent performance and durability of a wet ion-exchanged Fe–Ferrierite catalysts for N2O decomposition under conditions of nitric acid plants, especially in the presence of water (0.5% vol) and at a high space time W/F0(N2O) = 900 kgcat s mol-1. In contrast to io

  2. Runaway behavior and thermally safe operation of multiple liquid–liquid reactions in the semi-batch reactor: The nitric acid oxidation of 2-octanol

    NARCIS (Netherlands)

    Woezik, van B.A.A.; Westerterp, K.R.

    2002-01-01

    The thermal runaway behavior of an exothermic, heterogeneous, multiple reaction system has been studied in a cooled semi-batch reactor. The nitric acid oxidation of 2-octanol has been used to this end. During this reaction, 2-octanone is formed, which can be further oxidized to unwanted carboxylic a

  3. Response of marine and freshwater algae to nitric acid and elevated carbon dioxide levels simulating environmental effects of bolide impact

    Science.gov (United States)

    Boston, P. J.

    1988-01-01

    One of the intriguing facets of the Cretaceous-Tertiary extinction is the apparently selective pattern of mortality amongst taxa. Some groups of organisms were severely affected and some remained relatively unscathed as they went through the K/T boundary. While there is argument concerning the exact interpretation of the fossil record, one of the best documented extinctions at the Cretaceous-Tertiary boundary is that of the calcareous nannoplankton. These organisms include coccolithic algae and foraminiferans. Attempts to explain their decline at the K/T boundary center around chemistry which could affect their calcium carbonate shells while leaving their silica-shelled cousins less affected or unaffected. Two environmental consequences of an extraterrestrial body impact which were suggested are the production of large quantities of nitrogen oxides generated by the shock heating of the atmosphere and the possible rise in CO2 from the dissolution of CaCO3 shells. Both of these phenomena would acidify the upper layers of the oceans and bodies of freshwater not otherwise buffered. The effects of nitric acid, carbon dioxide, or both factors on the growth and reproduction of calcareous marine coccoliths and non-calcareous marine and freshwater species of algae were considered. These experiments demonstrate that nitric acid and carbon dioxide have significant effects on important aspects of the physiology and reproduction of modern algae representative of extinct taxa thought to have suffered significant declines at the Cretaceous-Tertiary boundary. Furthermore, calcareous species showed more marked effects than siliceous species and marine species tested were more sensitive than freshwater species.

  4. Properties of silica fume procured from natural diatomite and its usage in the production of vacuum insulation panels

    Directory of Open Access Journals (Sweden)

    V.P. Selyaev

    2013-11-01

    Full Text Available The article shows the results of the research of silica fume particles procured from diatomite from Atemar deposit by means of separating silicic acid from colloidal dissolved state into the sediment. The objective of the work was to define thermal-physical and structural characteristics of the silica fume. The research included IR-spectrometry, granulometry, thermal gravimetric analysis, X-ray structural analysis, optical microscopy, and small angle X-Ray scattering. As a result of the research, the silica fume was defined to predominantly consist of amorphous silicon dioxide and had the developed pore structure of particles. A large number of nanosized particles and pores decreases heat transmission and increases reactive capability, that gives opportunity of using the powder silica fume as an active agent in dry mixes and concrete composites, as a component of sponge-glass, and as a filler material in vacuum insulation panel.

  5. Inhibition of nitric oxide synthase lowers fatty acid oxidation in preeclampsia-like mice at early gestational stage

    Institute of Scientific and Technical Information of China (English)

    MA Rui-qiong; SUN Min-na; YANG Zi

    2011-01-01

    Background Preeclampsia is one of hypertensive disorders in pregnancy. It is associated with abnormal lipid metabolism, including fatty acid oxidation metabolism. Long chain 3-hydroxyacyI-CoA dehydrogenase (LCHAD) plays an indispensable role in the oxidation of fatty acids. It has been reported that nitric oxide (NO) is one of the regulatory factors of the fatty acid oxidation pathway. The aim of this research was to investigate whether the nitric oxide synthase (NOS)inhibitor L-NAME may cause down-regulation of LCHAD in the pathogenesis of preeclampsia.Methods Pregnant wild-type (WT) mice were treated with L-NAME or normal saline (NS) during gestation days 7-18 (early group), days 11-18 (mid group) and days 16-18 (late group), and apoE-/- mice served as a control. Systolic blood pressure (SBP), urine protein, feto-placental outcome, plasma lipid levels and NO concentrations were measured, and the expression of mRNA and protein for LCHAD in placental tissue were determined by real-time polymerase chain reaction (RT-PCR) and Western blotting, respectively.Results In WT and apoE-/- mice, SBP and urinary protein increased following L-NAME injection. Fetal and placental weights and NO concentrations were reduced and total cholesterol, triglycerides and free fatty acid levels were increased in early and mid L-NAME groups in WT and apoE-/- mice, compared with the NS group. There was no significant difference between the late L-NAME group and NS group. RT-PCR and Western blotting analysis showed that the mRNA and protein levels of LCHAD expression were significantly down-regulated in the early and mid L-NAME groups but not in the late L-NAME group in the WT and apoE-/- mice compared with the corresponding NS groups.Conclusions Inhibition of NO in early and mid gestation in mice may cause hyperlipidemia and suppression of fatty acid oxidation, whereas preeclampsia-like conditions in late gestation may be a maternal vascular response to inhibition of NO.

  6. Diazeniumdiolate-Doped Poly(lactic-co-glycolic acid)-Based Nitric Oxide Releasing Films as Antibiofilm Coatings

    Science.gov (United States)

    Cai, Wenyi; Wu, Jianfeng; Xi, Chuanwu; Meyerhoff, Mark, E.

    2012-01-01

    Nitric oxide (NO) releasing films with a bilayer configuration are fabricated by doping dibutyhexyldiamine diazeniumdiolate (DBHD/N2O2) in a poly(lactic-co-glycolic acid) (PLGA) layer and further encapsulating this base layer with a silicone rubber top coating. By incorporating pH sensitive dyes within the films, pH changes in the PLGA layer are visualized and correlated with the NO release profiles (flux vs. time). It is demonstrated that PLGA acts as both a promoter and controller of NO release from the coating by providing protons through its intrinsic acid residues (both end-groups and monomeric acid impurities) and hydrolysis products (lactic acid and glycolic acid). Control of the pH changes within the PLGA layer can be achieved by adjusting the ratio of DBHD/N2O2 and utilizing PLGAs with different hydrolysis rates. Coatings with a variety of NO release profiles are prepared with lifetimes of up to 15 d at room temperature (23 °C) and 10 d at 37 °C. When incubated in a CDC flow bioreactor for a one-week period at RT or 37 °C, all the NO releasing films exhibit considerable antibiofilm properties against gram-positive S. aureus and gram-negative E. coli. In particular, compared to the silicone rubber surface alone, an NO releasing film with a base layer of 30 wt% DBHD/N2O2 mixed with poly(lactic acid) exhibits an ~98.4% reduction in biofilm biomass of S. aureus and ~ 99.9% reduction for E. coli at 37 °C. The new diazeniumdiolate-doped PLGA-based NO releasing coatings are expected to be useful antibiofilm coatings for a variety of indwelling biomedical devices (e.g., catheters). PMID:22841918

  7. Asphalt fume dermal carcinogenicity potential: I. dermal carcinogenicity evaluation of asphalt (bitumen) fume condensates.

    Science.gov (United States)

    Clark, Charles R; Burnett, Donald M; Parker, Craig M; Arp, Earl W; Swanson, Mark S; Minsavage, Gary D; Kriech, Anthony J; Osborn, Linda V; Freeman, James J; Barter, Robert A; Newton, Paul E; Beazley, Shelley L; Stewart, Christopher W

    2011-10-01

    Asphalt (bitumen) fume condensates collected from the headspace above paving and Type III built up roofing asphalt (BURA) tanks were evaluated in two-year dermal carcinogenicity assays in male C3H/HeNCrl mice. A third sample was generated from the BURA using a NIOSH laboratory generation method. Similar to earlier NIOSH studies, the BURA fume condensates were applied dermally in mineral oil twice per week; the paving sample was applied 7 days/week for a total weekly dose of 50 mg/wk in both studies. A single benign papilloma was observed in a group of 80 mice exposed to paving fume condensate at the end of the two-year study and only mild skin irritation was observed. The lab generated BURA fume condensate resulted in statistically significant (P<0.0001) increases in squamous cell carcinomas (35 animals or 55% of animals at risk). The field-matched BURA condensate showed a weaker but significant (P=0.0063) increase (8 carcinomas or 13% of animals) and a longer average latency (90 weeks vs. 76 for the lab fume). Significant irritation was observed in both BURA condensates. It is concluded that the paving fume condensate was not carcinogenic under the test conditions and that the field-matched BURA fume condensate produced a weak tumor response compared to the lab generated sample.

  8. Solvent extraction of nitric acid,uranium(VI) and thorium(IV) by N,N,N',N'-tetrahexylsuccinylamide

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    A new kind of diamideN,N,N',N'-tetrahexylsuccinylamide (THSA)wassynthesized,characterized and used for the extraction of HNO3,U(VI) and Th(IV)in a diluent composed of 0.5 volume fraction1,2,4-trimethy benzene(TMB) and 0.5 volume fraction kerosene(OK).Extraction distribution coefficients of U(VI) and Th(IV) as functionsof aqueous nitric acid concentration, extractant concentration,temperature and salting-out agent (LiNO3) have been studied, and it is found that THSA as an extractant is superior to TBP for extraction ofU(VI) and Th(IV).Back extraction was also studied.At low acidity, themain adduct of THSA and HNO3 is HNO3.THSA.THSA.(HNO3)2 and THSA.(HNO3)3 are also found at high acidity.The compositions of extracted species, apparent equilibrium constants and enthalpies ofextraction reactions have also been calculated.

  9. Diglycolic acid modified zirconium phosphate and studies on the extraction of Am(III) and Eu(III) from dilute nitric acid medium

    Energy Technology Data Exchange (ETDEWEB)

    Selvan, B. Robert; Suneesh, A.S.; Venkatesan, K.A.; Antony, M.P. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Fuel Chemistry Division; Dasthaiah, K.; Gardas, R.L. [Indian Institute of Technology - Madras, Chennai (India). Dept. of Chemistry

    2017-06-01

    Diglycolic acid modified zirconium phosphate (ZrP-DGA) was prepared and studied for the extraction of Am(III) and Eu(III) from dilute nitric acid medium. The distribution coefficient (K{sub d}, mL.g{sup -1}) of Am(III) and Eu(III) was measured as a function of time, pH and concentration of Eu(III) ion etc. The K{sub d} of Am(III) and Eu(III) increased with increase of pH, reached a maximum value of distribution coefficient at pH 1.5 - 2, followed by decrease in K{sub d} values. Rapid extraction of Am(III) and Eu(III) in ZrP-DGA was observed followed by the establishment of equilibrium occurred in 100 min. Kinetics of extraction was fitted in to pseudo second order rate equation. The amount of Eu(III) loaded in ZrP-DGA increased with increase in the concentration of Eu(III) ion in aqueous phase and the isotherm was fitted in to Langmuir and Freundlich adsorption models. The extraction of Am(III) in ZrP-DGA was higher as compared to Eu(III) and the interference of Eu(III) on the extraction of Am(III) was studied. The distribution coefficient of some lanthanides in ZrP-DGA was measured and the K{sub d} of lanthanides increased across the lanthanide series. The extracted trivalent metal ions were recovered in three contacts of loaded ZrP-DGA with 0.5 M nitric acid.

  10. Ascorbic acid improves brachial artery vasodilation during progressive handgrip exercise in the elderly through a nitric oxide-mediated mechanism.

    Science.gov (United States)

    Trinity, Joel D; Wray, D Walter; Witman, Melissa A H; Layec, Gwenael; Barrett-O'Keefe, Zachary; Ives, Stephen J; Conklin, Jamie D; Reese, Van; Zhao, Jia; Richardson, Russell S

    2016-03-15

    The proposed mechanistic link between the age-related attenuation in vascular function and free radicals is an attractive hypothesis; however, direct evidence of free radical attenuation and a concomitant improvement in vascular function in the elderly is lacking. Therefore, this study sought to test the hypothesis that ascorbic acid (AA), administered intra-arterially during progressive handgrip exercise, improves brachial artery (BA) vasodilation in a nitric oxide (NO)-dependent manner, by mitigating free radical production. BA vasodilation (Doppler ultrasound) and free radical outflow [electron paramagnetic resonance (EPR) spectroscopy] were measured in seven healthy older adults (69 ± 2 yr) during handgrip exercise at 3, 6, 9, and 12 kg (∼13-52% of maximal voluntary contraction) during the control condition and nitric oxide synthase (NOS) inhibition via N(G)-monomethyl-L-arginine (L-NMMA), AA, and coinfusion of l-NMMA + AA. Baseline BA diameter was not altered by any of the treatments, while L-NMMA and L-NMMA + AA diminished baseline BA blood flow and shear rate. AA improved BA dilation compared with control at 9 kg (control: 6.5 ± 2.2%, AA: 10.9 ± 2.5%, P = 0.01) and 12 kg (control: 9.5 ± 2.7%, AA: 15.9 ± 3.7%, P vasodilation compared with control and when combined with AA eliminated the AA-induced improvement in BA vasodilation. Free radical outflow increased with exercise intensity but, interestingly, was not attenuated by AA. Collectively, these results indicate that AA improves BA vasodilation in the elderly during handgrip exercise through an NO-dependent mechanism; however, this improvement appears not to be the direct consequence of attenuated free radical outflow from the forearm.

  11. Cross-talk between calcium-calmodulin and nitric oxide in abscisic acid signaling in leaves of maize plants

    Institute of Scientific and Technical Information of China (English)

    Jianrong Sang; Aying Zhang; Fan Lin; Mingpu Tan; Mingyi Jiang

    2008-01-01

    Using pharmacological and biochemical approaches,the signaling pathways between hydrogen peroxide (H2O2),calcium (Ca2+)-calmodulin (CAM),and nitric oxide (NO) in abscisic acid (ABA)-induced antioxidant defense were investigated in leaves of maize (Zea mays L.) plants.Treatments with ABA,H2O2,and CaCI2 induced increases in the generation of NO in maize mesophyll cells and the activity of nitric oxide synthase (NOS) in the cytosolic and microsomal fractions of maize leaves.However,such increases were blocked by the pretreatments with Ca2+ inhibitors and CaM antagonists.Meanwhile,pretreatments with two NOS inhibitors also suppressed the Ca2+-induced increase in the production of NO.On the other hand,treatments with ABA and the NO donor sodium nitroprusside (SNP) also led to increases in the concentration of cytosolic Ca2+ in protoplasts of mesophyll cells and in the expression of calmodulin 1 (CaMI) gene and the contents of CaM in leaves of maize plants,and the increases induced by ABA were reduced by the pretreatments with a NO scavenger and a NOS inhibitor.Moreover,SNP-induced increases in the expression of the antioxidant genes superoxide dismutase 4 (SOD4),cytosolic ascorbate peroxidase (cAPX),and glutathione reductase 1 (GRI) and the activities of the chloroplastic and cytosolic antioxidant enzymes were arrested by the pretreatments with Ca2+ inhibitors and CaM antagonists.Our results suggest that Ca2+-CaM functions both upstream and downstream of NO production,which is mainly from NOS,in ABA- and H2O2-induced antioxidant defense in leaves of maize plants.

  12. New Inducible Nitric Oxide Synthase and Cyclooxygenase-2 Inhibitors, Nalidixic Acid Linked to Isatin Schiff Bases via Certain l-Amino Acid Bridges

    Directory of Open Access Journals (Sweden)

    Ahmed M. Naglah

    2016-04-01

    Full Text Available A series of new Schiff bases were synthesized by condensation of isatins with the nalidixic acid-l-amino acid hydrazides. Prior to hydrazide formation, a peptide linkage has been prepared via coupling of nalidixic acid with appropriate l-amino acid methyl esters to yield 3a–c. The chemical structures of the new Schiff bases (5b and 5d–h were confirmed by means of IR, NMR, mass spectroscopic, and elemental analyses. The anti-inflammatory activity of these Schiff bases was evaluated via measurement of the expressed inducible nitric oxide synthase (iNOS and cyclooxygenase-2 (COX-2 in the lipopolysaccharide (LPS-stimulated RAW264.7 macrophage cells model. The Schiff bases exhibited significant dual inhibitory effect against the induction of the pro-inflammatory iNOS and COX-2 proteins with variable potencies. However, they strongly down-regulated the iNOS expression to the level of 16.5% ± 7.4%–42.2% ± 19.6% compared to the effect on COX-2 expression (<56.4% ± 3.1% inhibition at the same concentration (10 μM. The higher iNOS inhibition activity of the tested Schiff bases, relative to that of COX-2, seems to be a reflection of the combined suppressive effects exerted by their nalidixic acid, isatins (4a–c, and l-amino acid moieties against iNOS expression. These synthesized nalidixic acid-l-amino acid-isatin conjugates can be regarded as a novel class of anti-inflammatory antibacterial agents.

  13. Reactions between water-soluble organic acids and nitrates in atmospheric aerosols: Recycling of nitric acid and formation of organic salts

    Science.gov (United States)

    Wang, Bingbing; Laskin, Alexander

    2014-03-01

    Atmospheric particles often include a complex mixture of nitrate and secondary organic materials accumulated within the same individual particles. Nitrate as an important inorganic component can be chemically formed in the atmosphere. For instance, formation of sodium nitrate (NaNO3) and calcium nitrate (Ca(NO3)2) occurs when nitrogen oxides and nitric acid (HNO3) react with sea salt and calcite, respectively. Organic acids contribute a significant fraction of photochemically formed secondary organics that can condense on the preexisting nitrate-containing particles. Here we present a systematic microanalysis study on chemical composition of laboratory-generated particles composed of water-soluble organic acids and nitrates (i.e., NaNO3 and Ca(NO3)2) using computer-controlled scanning electron microscopy with energy-dispersive X-ray microanalysis and Fourier transform infrared microspectroscopy. The results show that water-soluble organic acids can react with nitrates and release gaseous HNO3 during the dehydration process. These reactions are attributed to acid displacement of nitrate with weak organic acids driven by the evaporation of HNO3 into gas phase because of its relatively high volatility. The reactions result in significant nitrate depletion and formation of organic salts in mixed organic acids/nitrate particles that, in turn, may affect their physical and chemical properties relevant to atmospheric environment and climate. Airborne nitrate concentrations are estimated by thermodynamic calculations corresponding to various nitrate depletions in selected organic acids of atmospheric relevance. The results indicate a potential mechanism of HNO3 recycling that may further affect concentrations of gas and condensed phase species in the atmosphere and the heterogeneous reaction chemistry between them.

  14. Production of 15N-enriched nitric acid (H15NO3

    Directory of Open Access Journals (Sweden)

    C. R. Sant Ana Filho

    2008-12-01

    Full Text Available Techniques that employ 15N have proved to be an important tool in many areas of the agronomic and biomedical sciences. Nevertheless, their use is limited by methodological difficulties and by the price of compounds in the international market. Nitric compounds (15NO3- have attracted the interest of researchers. However, these compounds are not currently produced in Brazil. Thus, in the present work H15NO3 was obtained from the oxidation of anhydrous 15NH3. The method we used differs from the industrial process in that the absorption tower is replaced with a polytetrafluoroethylene-lined, stainless-steel hydration reactor. The process output was evaluated based on the following parameters: reaction temperature; ratio of reagents; pressure and flow of 15NH3(g through the catalyst (Pt/Rh. The results showed that, at the best conditions (500 ºC; 50 % excess O2; 0.4 MPa; and 3.39 g.min-1 of 15NH3, a conversion percentage (N-15NH3 to N-15NO3- of 62.2 %, an overall nitrogen balance (N-15NH3 + N-15NO3- of 86.8 %, and purity higher than 99 % could be obtained.

  15. Macroscopic, thermodynamic, kinetic and microscopic study of nitric acid pickling of Elektron 21 (EV31A magnesium alloy

    Directory of Open Access Journals (Sweden)

    Benjamin Mouls

    2014-12-01

    Full Text Available The study of pickling of the EL21T6 substrate in a nitric acid bath firstly provided knowledge of the influence of the different experimental parameters (concentration of acid, temperature and stirring of the solution in relation to the etching rate. This experimental part led to the choice of standard pickling (Tbath = 25 °C, moderate stirring (250 rpm, [HNO3] = 1.20 mol/L, duration of 2 min so as to obtain constant removal of material, even after several uses of the pickling bath. SEM observations also confirmed that in these operating conditions, pickling concerns both the grains of the matrix and the precipitates of type Mg3(Nd, Gd, leading to uniform removal of material from the surface. Working from a number of assumptions, thermodynamic and chemical kinetic studies then allowed a pickling mechanism to be proposed and led to obtaining values for the corresponding kinetic parameters (order of reaction, constant of mean rate, activation energy to be obtained.

  16. Solution extraction of several lanthanides from nitric acid with isohexyl-BTP in [Cnmim][NTf2] ionic liquid

    Institute of Scientific and Technical Information of China (English)

    赵龙; 董珍; 马国龙; 袁威津

    2015-01-01

    The extraction behavior of several lanthanides (La3+, Eu3+, Lu3+) from nitric acid (HNO3) solution was studied using a novel extraction system based on 2,6-bis(5,6-dihexyl-1,2,4-triazin-3-yl) pyridine (isohexyl-BTP) as extractant in 1-alkyl-3-me-thylimidazolium bis(trifluoromethylsufonyl)imide ([Cnmim][NTf2]) ionic liquid. Isohexyl-BTP in ionic liquids exhibited remarkably better extraction performance for lanthanides than that in octanol-dodecane (3:7 v/v) system. Lower HNO3 concentration and short alkyl chain length of [Cnmim]+were more favourable for removal of lanthanides. Besides, it was confirmed that isohexyl-BTP in ILs formed a 1:3 complex [Ln(BTP)3(NO3)n](3–n)+(n=0, 1) by slope analysis. In addition, [C2mim][NTf2] preferred to extract lanthanides via a cation exchange mechanism at lower acidity, which was proved via UV-Vis measurement. It was speculated that extraction mechanism shifted from cation exchange to neutral species extraction with increase in HNO3 concentration and alkyl chain length of [Cnmim]+due to the H+completion, NO3–inhibition and hydrophobicity of IL.

  17. The influence of oxidation with nitric acid on the preparation and properties of active carbon enriched in nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Pietrzak, Robert [Laboratory of Coal Chemistry and Technology, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznan (Poland)], E-mail: pietrob@amu.edu.pl; Nowicki, Piotr; Wachowska, Helena [Laboratory of Coal Chemistry and Technology, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznan (Poland)

    2009-01-01

    The effect of oxidation by 20% nitric acid on the properties and performance of active carbons enriched with nitrogen by means of the reaction with urea in the presence of air has been studied. The study has been made on demineralised orthocoking coal and the carbonisates obtained from it at 600 or 700 deg. C, subjected to the processes of nitrogenation, oxidation and activation with KOH in different sequences. The amount of nitrogen introduced into the carbon with the aid of urea has been found to depend on the stage at which the process of nitrogenation was performed. The process of oxidation of the demineralised coal and the active carbon obtained from the former has been found to favour nitrogen introduction into the carbon structure. In the process of nitrogenation of the carbonisates the amount of nitrogen introduced has inversely depended on the temperature of carbonisation. The modifications of the processes permitted obtaining materials of different textural parameters, different acid-base character of the surface and different iodine sorption capacity.

  18. The Arabidopsis aleurone layer responds to nitric oxide, gibberellin, and abscisic acid and is sufficient and necessary for seed dormancy.

    Science.gov (United States)

    Bethke, Paul C; Libourel, Igor G L; Aoyama, Natsuyo; Chung, Yong-Yoon; Still, David W; Jones, Russell L

    2007-03-01

    Seed dormancy is a common phase of the plant life cycle, and several parts of the seed can contribute to dormancy. Whole seeds, seeds lacking the testa, embryos, and isolated aleurone layers of Arabidopsis (Arabidopsis thaliana) were used in experiments designed to identify components of the Arabidopsis seed that contribute to seed dormancy and to learn more about how dormancy and germination are regulated in this species. The aleurone layer was found to be the primary determinant of seed dormancy. Embryos from dormant seeds, however, had a lesser growth potential than those from nondormant seeds. Arabidopsis aleurone cells were examined by light and electron microscopy, and cell ultrastructure was similar to that of cereal aleurone cells. Arabidopsis aleurone cells responded to nitric oxide (NO), gibberellin (GA), and abscisic acid, with NO being upstream of GA in a signaling pathway that leads to vacuolation of protein storage vacuoles and abscisic acid inhibiting vacuolation. Molecular changes that occurred in embryos and aleurone layers prior to germination were measured, and these data show that both the aleurone layer and the embryo expressed the NO-associated gene AtNOS1, but only the embryo expressed genes for the GA biosynthetic enzyme GA3 oxidase.

  19. Determination of Uranyl Nitrate and Nitric Acid Based on Density and Conductivity Measurements

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>Measurement of the uranium and acidity plays an important role in process control of spent fuel reprocessing. The main chemical compositions including a mount of U solution in spent fuel reprocessing

  20. Stabilization of heavy metals in MSWI fly ash using silica fume

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xinying; Chen, Quanyuan [School of Environment Science and Engineering, Donghua University, Shanghai 201620 (China); State Environmental Protection Engineering Center for Pollution Treatment and Control in Textile Industry, Donghua University, Shanghai 201620 (China); Zhou, Yasu [School of Environment Science and Engineering, Donghua University, Shanghai 201620 (China); Tyrer, Mark [Mineral Industry Research Organisation, Solihull B37 7HB (United Kingdom); Yu, Yang [School of Environment Science and Engineering, Donghua University, Shanghai 201620 (China)

    2014-12-15

    Highlights: • The stabilization of heavy metals in MSWI fly ash was investigated. • The addition of silica fume effectively reduced the leaching of Pb and Cd. • The relation of solid phase transformation and leaching behavior of heavy metals was discussed. - Abstract: The objective of this work was to investigate the feasibility and effectiveness of silica fume on stabilizing heavy metals in municipal solid waste incineration (MSWI) fly ash. In addition to compressive strength measurements, hydrated pastes were characterized by X-ray diffraction (XRD), thermal-analyses (DTA/TG), and MAS NMR ({sup 27}Al and {sup 29}Si) techniques. It was found that silica fume additions could effectively reduce the leaching of toxic heavy metals. At the addition of 20% silica fume, leaching concentrations for Cu, Pb and Zn of the hydrated paste cured for 7 days decreased from 0.32 mg/L to 0.05 mg/L, 40.99 mg/L to 4.40 mg/L, and 6.96 mg/L to 0.21 mg/L compared with the MSWI fly ash. After curing for 135 days, Cd and Pb in the leachates were not detected, while Cu and Zn concentrations decreased to 0.02 mg/L and 0.03 mg/L. The speciation of Pb and Cd by the modified version of the European Community Bureau of Reference (BCR) extractions showed that these metals converted into more stable state in hydrated pastes of MSWI fly ash in the presence of silica fume. Although exchangeable and weak-acid soluble fractions of Cu and Zn increased with hydration time, silica fume addition of 10% can satisfy the requirement of detoxification for heavy metals investigated in terms of the identification standard of hazardous waste of China.

  1. Persistence of Change: Fume Hood Campaign Lessons

    Science.gov (United States)

    Feder, Elah; Robinson, Jennifer; Wakefield, Sarah

    2012-01-01

    Purpose: Sustainability initiatives typically operate for a limited time period, but it is often unclear whether they have lasting effects. The purpose of this paper is to examine a laboratory fume hood campaign, in order to identify factors that might contribute or detract from long-term change persistence. Design/methodology/approach: The…

  2. Interannual variations of early winter Antarctic polar stratospheric cloud formation and nitric acid observed by CALIOP and MLS

    Science.gov (United States)

    Lambert, Alyn; Santee, Michelle L.; Livesey, Nathaniel J.

    2016-12-01

    We use satellite-borne measurements collected over the last decade (2006-2015) from the Aura Microwave Limb Sounder (MLS) and the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) to investigate the nitric acid distribution and the properties of polar stratospheric clouds (PSCs) in the early winter Antarctic vortex. Frequently, at the very start of the winter, we find that synoptic-scale depletion of HNO3 can be detected in the inner vortex before the first lidar detection of geophysically associated PSCs. The generation of "sub-visible" PSCs can be explained as arising from the development of a solid particle population with low number densities and large particle sizes. Assumed to be composed of nitric acid trihydrate (NAT), the sub-visible PSCs form at ambient temperatures well above the ice frost point, but also above the temperature at which supercooled ternary solution (STS) grows out of the background supercooled binary solution (SBS) distribution. The temperature regime of their formation, inferred from the simultaneous uptake of ambient HNO3 into NAT and their Lagrangian temperature histories, is at a depression of a few kelvin with respect to the NAT existence threshold, TNAT. Therefore, their nucleation requires a considerable supersaturation of HNO3 over NAT, and is consistent with a recently described heterogeneous nucleation process on solid foreign nuclei immersed in liquid aerosol. We make a detailed investigation of the comparative limits of detection of PSCs and the resulting sequestration of HNO3 imposed by lidar, mid-infrared, and microwave techniques. We find that the temperature history of air parcels, in addition to the local ambient temperature, is an important factor in the relative frequency of formation of liquid/solid PSCs. We conclude that the initiation of NAT nucleation and the subsequent development of large NAT particles capable of sedimentation and denitrification in the early winter do not emanate from an ice

  3. Development of a Technology for Treating Wastewater Contaminated with Nitric Acid

    Directory of Open Access Journals (Sweden)

    Liz Mabel Ríos Hidalgo

    2013-01-01

    Full Text Available The production process of nitroaromatic hazardous compounds, with the generation of acidic wastewater, represents a significant danger for the health and safety of the workers and the environment. The present study is focused on the development of an efficient installation to treat acidic wastewater resulting from the synthesis process of nitroaromatic compound, considering workers safety and environmental criteria. In this research, a detailed study of the different alternatives that can be used for effective and safe treatment of acidic wastewater was performed. The analysis of several technological schemes for the acidic wastewaters neutralization and the selection of the most feasible alternative from a technical-economic point of view were carried out. The simulation and mathematical modeling developed in this research represent a significant advance in the knowledge of this process for working in a much more secure form. The technological scheme of the process was defined, and the design of the main and auxiliary equipment as well as the piping system was carried out using different computational programs. Finally, this paper proposes a technological design for the treatment of acidic wastewater generated by the production process of nitroaromatic compound, which represents the basic criteria for the further design, construction, and equipment installation of the plant.

  4. Interactions of Gas-Phase Nitric/Nitrous Acids and Primary Organic Aerosol in the Atmosphere of Houston, TX

    Science.gov (United States)

    Ziemba, L. D.; Griffin, R. J.; Dibb, J. E.; Anderson, C. H.; Whitlow, S. I.; Lefer, B. L.; Flynn, J.; Rappenglück, B.

    2007-12-01

    Concentrations of aerosol and gas-phase pollutants were measured on the roof of an 18-story building during the Texas Air Quality Study II Radical and Aerosol Measurement Project (TRAMP) from August 15 through September 28, 2006. Aerosol measurements included size-resolved, non-refractory mass concentrations of ammonium, nitrate, sulfate, chloride, and organic aerosol in submicron particles using an Aerodyne quadrupole aerosol mass spectrometer (Q-AMS). Particulate water-soluble organic carbon (PWSOC) was quantified using a mist chamber/total organic carbon analysis system. Concentration data for gas-phase pollutants included those for nitric acid (HNO3), nitrous acid (HONO), and hydrochloric acid (HCl) collected using a mist chamber/ion chromatographic technique, oxides of nitrogen (NOx) collected using a chemiluminescent method, and carbon monoxide (CO) collected using an infrared gas correlation wheel instrument. Coincident increases in nitrate and organic aerosol mass concentrations were observed on many occasions throughout the measurement campaign, most frequently during the morning rush hour. Based on the lack of organic aerosol processing (defined by the ratio of m/z = 44/57 in the Q-AMS spectra), strong correlation with NOx and CO, and a lack of significant increase in PWSOC concentration, the spikes in organic aerosol were likely associated with primary organic aerosol (POA). During these events, gas-phase HNO3 concentration decreases were observed simultaneously with increases in gas-phase HONO concentrations. These data likely indicate uptake of HNO3 and subsequent heterogeneous conversion to HONO involving POA. Preliminary calculations show that HNO3 partitioning could account for the majority of the observed HONO and aerosol nitrate concentrations during these events. Q-AMS chloride and HCl data also indicate uptake of chloride by particles during these events. This phenomenon was also observed during the night, but these nocturnal events were less

  5. Investigation of the direct and indirect electrochemical oxidation of hydrazine in nitric acid medium on platinum; Etude de l`oxydation electrochimique directe et indirecte de l`hydrazine en milieu acide nitrique sur platine

    Energy Technology Data Exchange (ETDEWEB)

    Cames, B

    1997-12-31

    In nuclear fuel processing by the PUREX process, the purification of plutonium in nitric acid medium requires the oxidation of Pu(III) to Pu(IV), and of hydrazinium nitrate to nitrogen. The study helped to characterize the electrochemical behavior of the oxidation of hydrazinium nitrate and the reduction of nitric acid to nitrous acid, a compound which can chemically oxidize hydrazinium nitrate and Pu(III). Electro-analytical studies on polycrystalline platinum showed that hydrazine is oxidized in two potential zones, which depend on the surface texture of the platinum anode. Electrolysis in separate compartments, carried out in medium-acid media (2 and 4 mo/l) in the potential zone where these processes take place, showed that, at 0.9 V/ECS, the hydrazine oxidation reactions involved are: a four-electron process (75 %) with nitrogen formation and a one-electron process (25 %) with formation of nitrogen and ammonium ion. By contrast, electrolysis carried out at 0.65 V/ECS (with reactivation of the electrode at - 0.2 V/ECS to remove the poison from the platinum) allowed the selective oxidation of hydrazine to nitrogen by the four-electron reaction. Nitric acid can only be reduced to nitrous acid in the absence of hydrazine. For medium-acid media ({<=} 6 mol/l), this reaction takes place at potentials below - 0.2 V/ECS. However, the production rate of nitrous acid (partial order 0 with respect to nitric acid) is very low compared with the values obtained for strongly-acid media (6 to 10 mol/l) at the potential of - 0.1 V/ECS. Note that, in concentrated nitric medium, the selectivity of the reduction reaction is 47 to 85 % for nitrous acid, depending on the nitric acid concentration (6 to 10 mol/l) and the potential imposed (- 0.1 {<=} E {<=} 0.6 V/ECS). A kinetic study helped to determine the hydrazine oxidation rates as a function of the operating conditions. In all cases, the reaction rate is of partial order 0 with respect to hydrazine. These studies accordingly

  6. Improvement effect on corrosion under heat flux in nitric acid solutions of anti-IGC stainless steel and high Cr-W-Si Ni base RW alloy

    Energy Technology Data Exchange (ETDEWEB)

    Doi, Masamitsu; Kiuchi, Kiyoshi; Yano, Masaya; Sekiyama, Yoshio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-03-01

    In the advanced purex reprocessing equipment, the higher corrosion resistance is required for materials because of the high corrosive environment caused from the thermodynamic decomposition of boiling nitric acid. The authors group has been developed the two types of new corrosion resistant materials for application to the reprocessing equipment. One is the type 304ULC stainless steel with controlled microstructure and decreased minor elements (EB-SAR). The other is the nickel base alloy with the ability of forming stable oxide film by addition of Cr, W and Si (RW alloy). In this study, the heat transfer tubes applied in diminished pressure was postulated. In addition to the dominant factors of heat conducting corrosion by the nitric acid solution, the effect of the heat flux and the concentration of the corrosive vanadium ions were investigated. (author)

  7. Kinetics study on the dissolution of UO2 particles by microwave and conventional heating in 4 mol/L nitric acid

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The dissolution of UO2 particles in 4 mol·L-1 nitric acid medium at temperatures of 90-110℃ by mi- crowave heating and conventional heating has been investigated, respectively. It is found that the dissolution ratios of UO2 particles by microwave heating were 10%-40% higher than that by conven- tional heating. Kinetics research shows that the dissolution of UO2 particles in 4 mol·L-1 nitric acid is controlled by the diffusion control model for microwave heating and by the surface reaction control model for conventional heating. The diffusion control model for the dissolution of UO2 particles by mi- crowave heating could be explained by the diffuseness on the surface of UO2 particles.

  8. [Determination of nine hazardous elements in textiles by inductively coupled plasma optical emission spectrometer after microwave-assisted dilute nitric acid extraction].

    Science.gov (United States)

    Chen, Fei; Xu, Dian-dou; Tang, Xiao-ping; Cao, Jing; Liu, Ya-ting; Deng, Jian

    2012-01-01

    Textiles are easily contaminated by heavy metals in the course of processing. In order to monitor the quality of textiles, a new method was developed for simultaneous determination of arsenic, antimony, lead, cadmium, chromium, cobalt, copper, nickel and mercury in textiles by inductively coupled plasma optical emission spectrometry (ICP-OES) after microwave-assisted dilute nitric acid extraction. After optimizing extraction conditions, we ultimately selected 5% nitric acid as extractant and 5 min as extraction time with the extraction temperature of 120 degrees C and instrument power of 400W in the microwave-assisted extraction procedure. Nine hazardous elements were detected sequentially by ICP-OES. The results showed that the detection limits were 0.3-15 microg x L(-1) and the recoveries 73.6%-105% with the RSDs (n = 3) of 0.1%-3%. The proposed method was successfully used to determine nine elements in cotton, wool, terylene and acrylic.

  9. Corrosion investigations on zircaloy-4 and titanium dissolver materials for MOX fuel dissolution in concentrated nitric acid containing fluoride ions

    Science.gov (United States)

    Jayaraj, J.; Krishnaveni, P.; Krishna, D. Nanda Gopala; Mallika, C.; Mudali, U. Kamachi

    2016-05-01

    Aqueous reprocessing of plutonium-rich mixed oxide fuels require fluoride as a dissolution catalyst in boiling nitric acid for an effective dissolution of the spent fuel. High corrosion rates were obtained for the candidate dissolver materials zircaloy-4 (Zr-4) and commercial pure titanium (CP-Ti grade 2) in boiling 11.5 M HNO3 + 0.05 M NaF. Complexing the fluoride ions either with Al(NO3)3 or ZrO(NO3)2 aided in decreasing the corrosion rates of Zr-4 and CP-Ti. From the obtained corrosion rates it is concluded that CP-Ti is a better dissolver material than Zr-4 for extended service life in boiling 11.5 M HNO3 + 0.05 M NaF, when complexed with 0.15 M ZrO(NO3)2. XPS analysis confirmed the presence of TiO2 and absence of fluoride on the surface of CP-Ti samples, indicating that effective complexation had occurred in solution leading to passivation of the metal and imparting high corrosion resistance.

  10. Nitric oxide involved in signal transduction of Jasmonic acid-induced stomatal closure of Vicia faba L.

    Institute of Scientific and Technical Information of China (English)

    LIU Xin; SHI Wuliang; ZHANG Shuqiu; LOU Chenghou

    2005-01-01

    Nitric oxide (NO) and Jasmonic acid (JA) are two key signaling molecules involved in many and diverse biological pathways in plants. Growing evidence suggested that NO signaling interacts with JA signaling. In this work, Our experiment showed that NO exists in guard cell of Vicia faba L., and NO is involved in signal transduction of JA- induced stomata closuring: (ⅰ) JA enhances NO synthesis in guard cell; (ⅱ) both JA and NO induced stomatal closure, and had dose response to their effects; (ⅲ) there are synergetic correlation between JA and lower NO concentration in regulation of stomatal movement; (ⅳ) JA-induced stomatal closure was largely prevented by 2-phenyl-4,4,5,5-tetrame- thylimidazoline-1-oxyl-3-oxide (PTIO), a specific NO scavenger. An inhibitor of NO synthase (NOS) in mammalian cells, NG-nitro-L-Arg-methyl eater (L-NAME) also inhibits plant NOS, repressing JA-induced NO generation and JA-induced stomatal closure. We presumed that NO mainly comes from NOS after JA treatment.

  11. Improvement of microwave-assisted digestion of milk powder with diluted nitric acid using oxygen as auxiliary reagent

    Energy Technology Data Exchange (ETDEWEB)

    Bizzi, Cezar A. [Departamento de Quimica, Universidade Federal de Santa Maria, 97105-900, Santa Maria, RS (Brazil); Instituto Nacional de Ciencia e Tecnologia de Bioanalitica, Campinas, SP (Brazil); Barin, Juliano S. [Departamento de Tecnologia e Ciencia dos Alimentos, Universidade Federal de Santa Maria, 97105-900, Santa Maria, RS (Brazil); Garcia, Edivaldo E. [Departamento de Quimica, Universidade Estadual de Maringa, 87100-900, Maringa, PR (Brazil); Nobrega, Joaquim A. [Departamento de Quimica, Universidade Federal de Sao Carlos, 13565-905, Sao Carlos, SP (Brazil); Dressler, Valderi L. [Departamento de Quimica, Universidade Federal de Santa Maria, 97105-900, Santa Maria, RS (Brazil); Instituto Nacional de Ciencia e Tecnologia de Bioanalitica, Campinas, SP (Brazil); Flores, Erico M.M., E-mail: ericommf@gmail.com [Departamento de Quimica, Universidade Federal de Santa Maria, 97105-900, Santa Maria, RS (Brazil); Instituto Nacional de Ciencia e Tecnologia de Bioanalitica, Campinas, SP (Brazil)

    2011-05-15

    The feasibility of using diluted HNO{sub 3} solutions under oxygen pressure for decomposition of whole and non-fat milk powders and whey powder samples has been evaluated. Digestion efficiency was evaluated by determining the carbon content in solution (digests) and the determination of Ca, Cd, Cu, Fe, K, Mg, Mn, Mo, Na, Pb and Zn was performed by inductively coupled plasma optical emission spectrometry and Hg by chemical vapor generation coupled to inductively coupled plasma mass spectrometry. Samples (up to 500 mg) were digested using HNO{sub 3} solutions (1 to 14 mol L{sup -1}) and the effect of oxygen pressure was evaluated between 2.5 and 20 bar. It was possible to perform the digestion of 500 mg of milk powder using 2 mol L{sup -1} HNO{sub 3} with oxygen pressure ranging from 7.5 to 20 bar with resultant carbon content in digests lower than 1700 mg L{sup -1}. Using optimized conditions, less than 0.86 mL of concentrated nitric acid (14 mol L{sup -1}) was enough to digest 500 mg of sample. The accuracy was evaluated by determination of metal concentrations in certified reference materials, which presented an agreement better than 95% (Student's t test, P < 0.05) for all the analytes.

  12. Recovery of Nickel from Reformer Catalysts of Direct Reduction, Using the Pressurized Dissolving Method in Nitric Acid

    Directory of Open Access Journals (Sweden)

    B. Abrar

    2016-10-01

    Full Text Available In the process of direct reduction of iron pellet and production of sponge iron, NiO/Al2O3 act as a catalyst for the generation of carbon monoxide and hydrogen by vapor and natural gas. As an expensive material used in MIDREX method for steel units, this type of catalyst has major environmental problems after accumulation. The steel industry in Iran hopes to employ the MIDREX technique for the 80 percent of the 50 million tons of steel. Thus, the problem of spent catalysts will become a serious environmental challenge. Through the hydrometallurgy method, the present study investigates a possible solution to the problem of catalyst depot (due to heavy metals such as nickel via nickel recovery, which may increase the possibility of selling or re-using the precious and expensive metal. The present research studied the Nickel recovery from spent catalysts of NiO/Al2O¬3 used in reduction gas reliefs of the production of sponge iron unit. In this study, the parameters of temperature, concentration, time and Rpm were studied using pressurized dissolving method. 100% efficiency was achieved at 140 °C for 120 minutes, nitric acid concentration of 1.5 mm, Rpm of 600 and 40 s/l 40 grams per liter.

  13. Synergistic extraction of U(VI) and Th(IV) from nitric acid media with HBMPPT and TBP in toluene

    Institute of Scientific and Technical Information of China (English)

    YUShaoning; BAOBorong

    1999-01-01

    The sysnergistic extraction of U(VI)and Th(IV) from nitric acid solution by HBMPPT(4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione) and TBP( tributylphosphate)in toluene was studied.The extraction ability of HBMPPT for U(VI) and Th(IV) was not so high.but when a little TBP was added in,the ability to extract U(VI) and Th(IV) was improved.The extracted complexes may be presented as UO2NO3.BMPPT.TBP and UO2(BMPPT)2.TBP for U(VI).and Th(NO3)3.BMPPT.TBP and Th(NO3)2(BMPPT)2.TBP for Th(IV),respectively,in the synergistic extraction system.The synergistic effect of HBMPPT and TBP makes the separation cofeeicient of U(VI)/Th (IV) or U(VI)/Eu(Ⅲ) reach a high value.

  14. Development of a chemical process using nitric acid-cerium(IV) for decontamination of high-level waste canisters

    Energy Technology Data Exchange (ETDEWEB)

    Bray, L.A.

    1988-06-01

    A simple and effective method was developed for contamination of high-level waste containers. This method of chemical decontamination is applicable to a wide variety of contaminated equipment found in the nuclear industry. The process employs a oxidant system (Ce(IV)) in nitric acid (HNO/sub 3/) solution to chemically mill a thin layer from the canister surface. Contaminated canisters are simply immersed in the solution at a controlled temperature and Ce(IV) concentration level. The spent solution is discarded to the high-level waste stream and added to subsequent glass batches. The Ce(IV)/HNO/sub 3/ solution has been shown to be effective in chemically milling the surface of stainless steel, similar to the electropolishing process, but without the need for an applied electrical current. West Valley (WV) staff had previously evaluated several canister decontamination methods, including electropolishing, liquid abrasive blast, high-pressure water wash, and ultrasonic cleaning, before the Ce(IV)/HNO/sub 3/ redox solution on treatment was selected. The initial concept involved continuous electrochemical regeneration of the ceric ion. Extensive in-cell pumping and close-coupled heat transfer and electrochemical equipment were required. The objective of this study, was to simplify the original concept. 2 refs., 16 figs., 4 tabs.

  15. Characterization of the early pulmonary inflammatory response associated with PTFE fume exposure

    Science.gov (United States)

    Johnston, C. J.; Finkelstein, J. N.; Gelein, R.; Baggs, R.; Oberdorster, G.; Clarkson, T. W. (Principal Investigator)

    1996-01-01

    Heating of polytetrafluoroethylene (PTFE) has been described to release fumes containing ultrafine particles (approximately 18 nm diam). These fumes can be highly toxic in the respiratory tract inducing extensive pulmonary edema with hemorrhagic inflammation. Fischer-344 rats were exposed to PTFE fumes generated by temperatures ranging from 450 to 460 degrees C for 15 min at an exposure concentration of 5 x 10(5) particles/cm3, equivalent to approximately 50 micrograms/m3. Responses were examined 4 hr post-treatment when these rats demonstrated 60-85% neutrophils (PMNs) in their lung lavage. Increases in abundance for messages encoding the antioxidants manganese superoxide dismutase and metallothionein (MT) increased 15- and 40-fold, respectively. For messages encoding the pro- and anti-inflammatory cytokines: inducible nitric oxide synthase, interleukin 1 alpha, 1 beta, and 6 (IL-1 alpha, IL-1 beta, and IL-6), macrophage inflammatory protein-2, and tumor necrosis factor-alpha (TNF alpha) increases of 5-, 5-, 10-, 40-, 40-, and 15-fold were present. Vascular endothelial growth factor, which may play a role in the integrity of the endothelial barrier, was decreased to 20% of controls. In situ sections were hybridized with 33P cRNA probes encoding IL-6, MT, surfactant protein C, and TNF alpha. Increased mRNA abundance for MT and IL-6 was expressed around all airways and interstitial regions with MT and IL-6 demonstrating similar spatial distribution. Large numbers of activated PMNs expressed IL-6, MT, and TNF alpha. Additionally, pulmonary macrophages and epithelial cells were actively involved. These observations support the notion that PTFE fumes containing ultrafine particles initiate a severe inflammatory response at low inhaled particle mass concentrations, which is suggestive of an oxidative injury. Furthermore, PMNs may actively regulate the inflammatory process through cytokine and antioxidant expression.

  16. 硝酸乙醇法测定纤维素含量%Determination the content of cellulose by nitric acid-ethanol method

    Institute of Scientific and Technical Information of China (English)

    王林风; 程远超

    2011-01-01

    根据秸秆乙醇的工艺特点,对硝酸乙醇法测定玉米秸秆、小麦秸秆、稻草及其预处理后物料的纤维素含量进行了研究.优化了粉碎时长、硝酸-乙醇混合液处理遍数、试样粒度及抽滤漏斗孔径四个参数.确定了优化后的测定方法:秸秆试样粉碎时长15 s,硝酸-乙醇混合液处理4遍,粒度40~60目,使用G2玻璃砂芯漏斗.秸秆预处理后物料试样粉碎时长3 s,硝酸-乙醇混合液处理3遍,粒度40~60目,使用G3玻璃砂芯漏斗.%The contents of cellulose of corn stalk, wheat straw, rice straw and the pretreated sample of straws have been researched by nitric acid-ethanol methodology according to the characteristics of straws biofuel ethanol. Four parameters as the duration of comminuting sample, the times of treating sample by nitric acid-ethanol liquid mixture, the particle size of sample and the aperture of tundish for sucking filtration have been optimized. The optimized pev-rameters: for straw sample, comminut 15 s, treat by nitric acid-ethanol liquid mixture 4 times, sample aperture 40 - 60 mesh, use G2 glass sand core tundish. For pretreated sample, comminut 3 s, treat by nitric acid-ethanol liquid mixture 3 times, sample aperture 40 - 60 mesh, use G3 glass sand core tundish.

  17. Determination of plutonium oxidation states in dilute nitric acid by complementary tristimulus colorimetry.

    Science.gov (United States)

    Silver, G L

    1967-06-01

    The preparation of reference standards for use in complementary tristimulus colorimetry for plutonium is described. Plutonium(III) and (VI) are prepared by hydrazine reduction and silver(II) oxidation, respectively, of plutonium(IV). Plutonium(V) is prepared by reduction of plutonium(VI) with ascorbic or sulphurous acid. A method for computerizing tristimulus colorimetry is presented, and the technique is extended to three dimensions ("quadristimulus colorimetry").

  18. Interaction of Polyamines, Abscisic Acid, Nitric Oxide, and Hydrogen Peroxide under Chilling Stress in Tomato (Lycopersicon esculentum Mill.) Seedlings.

    Science.gov (United States)

    Diao, Qiannan; Song, Yongjun; Shi, Dongmei; Qi, Hongyan

    2017-01-01

    Polyamines (PAs) play a vital role in the responses of higher plants to abiotic stresses. However, only a limited number of studies have examined the interplay between PAs and signal molecules. The aim of this study was to elucidate the cross-talk among PAs, abscisic acid (ABA), nitric oxide (NO), and hydrogen peroxide (H2O2) under chilling stress conditions using tomato seedlings [(Lycopersicon esculentum Mill.) cv. Moneymaker]. The study showed that during chilling stress (4°C; 0, 12, and 24 h), the application of spermidine (Spd) and spermine (Spm) elevated NO and H2O2 levels, enhanced nitrite reductase (NR), nitric oxide synthase (NOS)-like, and polyamine oxidase activities, and upregulated LeNR relative expression, but did not influence LeNOS1 expression. In contrast, putrescine (Put) treatment had no obvious impact. During the recovery period (25/15°C, 10 h), the above-mentioned parameters induced by the application of PAs were restored to their control levels. Seedlings pretreated with sodium nitroprusside (SNP, an NO donor) showed elevated Put and Spd levels throughout the treatment period, consistent with increased expression in leaves of genes encoding arginine decarboxylase (LeADC. LeADC1), ornithine decarboxylase (LeODC), and Spd synthase (LeSPDS) expressions in tomato leaves throughout the treatment period. Under chilling stress, the Put content increased first, followed by a rise in the Spd content. Exogenously applied SNP did not increase the expression of genes encoding S-adenosylmethionine decarboxylase (LeSAMDC) and Spm synthase (LeSPMS), consistent with the observation that Spm levels remained constant under chilling stress and during the recovery period. In contrast, exogenous Put significantly increased the ABA content and the 9-cis-epoxycarotenoid dioxygenase (LeNCED1) transcript level. Treatment with ABA could alleviate the electrolyte leakage (EL) induced by D-Arg (an inhibitor of Put). Taken together, it is concluded that, under chilling

  19. 六硝基茋在硝酸中的溶解度测定及关联%Solubility Measurement and Correlation of Hexanitrostilbene in Nitric Acid

    Institute of Scientific and Technical Information of China (English)

    许元刚; 李冬雪

    2014-01-01

    The solubility of 2 ,2',4 ,4',6 ,6'-Hexanitrostilbene , varied with concentration of nitric acid under 25℃, was measured using the laser monitor technique.The experimental data were correlated with the ( CNIBS )/Redlich -Kister empirical equation.The results showed that the solubility of HNS in nitric acid increased with concentration of nitric acid, and the predicted data by empirical equation had good agreement with the experiment data.%采用激光监测技术,测定了25℃下六硝基茋在不同浓度硝酸中的溶解度,用( CNIBS)/Redlich-Kister经验方程对实验数据进行了关联。结果表明六硝基茋在硝酸中的溶解度随硝酸浓度的增大而增加,用( CNIBS )/Redlich-Kister方程预测的溶解度值与实验值有较好的吻合。

  20. Nitro-fatty acids in plant signaling: New key mediators of nitric oxide metabolism

    Directory of Open Access Journals (Sweden)

    Capilla Mata-Pérez

    2017-04-01

    Full Text Available Recent studies in animal systems have shown that NO can interact with fatty acids to generate nitro-fatty acids (NO2-FAs. They are the product of the reaction between reactive nitrogen species and unsaturated fatty acids, and are considered novel mediators of cell signaling based mainly on a proven anti-inflammatory response. Although these signaling mediators have been described widely in animal systems, NO2-FAs have scarcely been studied in plants. Preliminary data have revealed the endogenous presence of free and protein-adducted NO2-FAs in extra-virgin olive oil (EVOO, which appear to be contributing to the cardiovascular benefits associated with the Mediterranean diet. Importantly, new findings have displayed the endogenous occurrence of nitro-linolenic acid (NO2-Ln in the model plant Arabidopsis thaliana and the modulation of NO2-Ln levels throughout this plant's development. Furthermore, a transcriptomic analysis by RNA-seq technology established a clear signaling role for this molecule, demonstrating that NO2-Ln was involved in plant-defense response against different abiotic-stress conditions, mainly by inducing the chaperone network and supporting a conserved mechanism of action in both animal and plant defense processes. Thus, NO2-Ln levels significantly rose under several abiotic-stress conditions, highlighting the strong signaling role of these molecules in the plant-protection mechanism. Finally, the potential of NO2-Ln as a NO donor has recently been described both in vitro and in vivo. Jointly, this ability gives NO2-Ln the potential to act as a signaling molecule by the direct release of NO, due to its capacity to induce different changes mediated by NO or NO-related molecules such as nitration and S-nitrosylation, or by the electrophilic capacity of these molecules through a nitroalkylation mechanism. Here, we describe the current state of the art regarding the advances performed in the field of NO2-FAs in plants and their

  1. Effect of Some Admixtures on the Hydration of Silica Fume and Hydrated Lime

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The effects of sodium salt of naphthalene formaldehyde sulfonic acid and stearic acid on the hydration of silica fume and Ca(0H)2 have been investigated. The hydration was carried out at 60℃ and W/S ratio of 4 for various time intervals namely, 1, 3, 7 and 28 days and in the presence of 0.2% and 5% superplasticizer and stearic acid. The results of the hydration kinetics show that both admixtures accelerate the hydration reaction of silica fume and calcium hydroxide during the first 7 days. Whereas, after 28 days hydration there is no significant effect. Generally, most of free calcium hydroxide seems to be consumed after 28 days. In addition, the phase composition as well as the microstructure of the formed hydrates was examined by using X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) respectively.

  2. Liquid-liquid extraction of palladium(II) from nitric acid by bis(2-ethylhexyl) sulphoxide

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, J.P. (Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Bombay 400085 (India)); Singh, R.K.; Sawant, S.R.; Varadarajan, N. (Power Reactor Fuel Reprocessing Plant, Bhabha Atomic Research Centre, Trombay, Bombay 400085 (India))

    1993-04-15

    The extraction of palladium(II) nitrate by bis(2-ethylhexyl) sulphoxide (BESO) was evaluated over a wide range of acidity, and BESO was shown to have a strong extraction ability toward this thiophilic 'soft' metal. Essentially quantitative extraction of trace and macro amounts of palladium is easily accomplished from about 8 M HNO 8 M HNO[sub 3] down to pH 2 solutions by 0.2 M BESO into toluene. Optimum conditions such as aqueous phase acidity, solvent, period of equilibration, aqueous to organic phase ratios, reagent concentration and strippant were established for the selective and reversible extraction and separation of palladium. Slope analyses applied to Pd(II) distribution experiments from nitrate solutions showed a predominant formation of the solvated organic phase complex Pd(NO[sub 3])[sub 2].2BESO. Recovery of the extractant from loaded palladium is easily accomplished by using sodium thiosulphate or a mixture of 2 M sodium carbonate+0.5 M ammonia solution. The extracted complex was characterized by elemental analysis and IR and UV-visible spectrometry, and its composition was confirmed to be Pd(NO[sub 3])[sub 2].2BESO

  3. Green Design on the Reaction of Copper and Nitric Acid%铜与硝酸反应的绿色化设计

    Institute of Scientific and Technical Information of China (English)

    张玉贞; 李先栓

    2011-01-01

    To achieve green ideas on chemical experiment teaching has to hold two critical points: One is that chemical reactions of harmful volatile materials must be carried out in completely sealed condition; The other is that products need harmlessly be treated for environment. In this paper, using U pipe, the reaction of copper and concentrated/dilute nitric acid can be guaranteed in sealed surroundings and the tail gas was harmlessly treated. The reaction of nitric oxide and concentrated nitric acid demonstrated that the gas product of the reaction of copper and concentrated nitric acid was nitrogen dioxide, which can provide strong criterion for correcting students' wrong ideas.%化学实验教学实现绿色化思想的关键有两点:一是挥发有害物质的化学反应在完全密封状态下进行;二是实验产物的无害化处理.利用U型管巧妙设计,可使铜与浓、稀硝酸反应的毒气实验在密闭环保中进行,同时达到了绿色化尾气处理利用NO与浓HNO3反应,可证明铜与浓硝酸反应为什么生成的是NO2而不是NO,从事实上为学生纠错提供了有力判据.

  4. Methemoglobinemia secondary to automobile exhaust fumes

    Energy Technology Data Exchange (ETDEWEB)

    Laney, R.F.; Hoffman, R.S. (Department of Emergency Medicine, Morristown Memorial Hospital, NJ (United States))

    1992-09-01

    Methemoglobinemia is an uncommon cause of cyanosis. A 28-year-old male presented to the emergency department cyanotic and short of breath after exposure to noxious automobile fumes. He did not improve with the administration of 100% oxygen therapy. The initial arterial blood gas with cooximetry was: pH of 7.38, PaCO2 of 43 mm Hg, PaO2 of 118 mm Hg, measured oxygen saturation of 70%, and a methemoglobin level of 24.8%. Methylene blue was given (2 mg/kg intravenously) and the patient's symptoms resolved. On the following day he was discharged home without complication. A comprehensive review of the literature revealed no reported cases of methemoglobinemia secondary to accidental exposure to exhaust fumes.17 references.

  5. The ν_3 and ν_4 Bands of Nitric Acid (HNO_3) at 7.6 μm for Atmospheric Studies

    Science.gov (United States)

    Perrin, A.; Flaud, J. M.; Ridolfi, M.; Carlotti, M.

    2012-06-01

    Nitric acid (HNO_3) plays an important role as a reservoir molecule of the NO_x (nitrogen oxides) species in the stratosphere. The three strongest infrared bands of nitric acid are located at 11 μm (ν_5 and 2ν_9 bands), 7.6 μm (the ν_3 and ν_4 bands at 1326 and 1303 cm-1) and 5.8 μm (ν_2 band). Although two times weaker than those located at 7.6 and 5.8 μm, the 11 μm region is the only one which is used for nitric acid retrievals in the atmosphere by several satellite instruments like MIPAS (Michelson Interferometer for Passive Atmospheric Sounding on ENVISAT) or ACE-FTS (ACE Fourier transform spectrometer on SCISAT). This is because the available spectroscopic parameters for HNO_3 in the HITRAN and GEISA databases are of very good quality in this spectral region. Of the two remaining bands, the 7.6 μm one is only partly masked by water, and therefore can be used also for nitric acid retrievals in the upper stratosphere. Moreover, because of their large difference in band intensity, combining measurements at 11 μm and 7.6 μm could maximize informations on the vertical distribution of HNO_3 in the atmosphere. However at 7.6 μm the spectroscopic parameters available in the HITRAN and GEISA databases are are not so good. Indeed, these parameters originate from a list generated more than 20 years ago. The low quality of the list at 7.6 μm prevents HNO_3 retrievals and severely affects the retrievals of several species absorbing in the 7.5-7.7 μm region, like SO_2. This work is a new and more accurate investigation of the line positions and intensities for the ν_3 and ν_4 bands of nitric acid located at 1326.187 and 1303.074 cm-1). For this task, we used new infrared laboratory data combined with a new theoretical model. Examples showing substantial improvements will be given. [1] Rothman et al. J. Quant. Spectrosc. Radiat. Transf., 110, 533-572, 2009 [2] Jacquinet et al. J. Quant. Spectrosc. Radiat. Transf., 112, 2395-2445, 2011 [3] A. Perrin, O. Lado

  6. Impact of sulfuric and nitric acids on carbonate dissolution, and the associated deficit of CO2 uptake in the upper-middle reaches of the Wujiang River, China

    Science.gov (United States)

    Huang, Qi-bo; Qin, Xiao-qun; Liu, Peng-yu; Zhang, Lian-kai; Su, Chun-tian

    2017-08-01

    Carbonate weathering and the CO2 consumption in karstic area are extensive affected by anthropogenic activities, especially sulfuric and nitric acids usage in the upper-middle reaches of Wujiang River, China. The carbonic acid would be substituted by protons from sulfuric and nitric acids which can be reduce CO2 absorption. Therefore, The goal of this study was to highlight the impacts of sulfuric and nitric acids on carbonate dissolution and the associated deficit of CO2 uptaking during carbonate weathering. The hydrochemistries and carbon isotopic signatures of dissolved inorganic carbon from groundwater were measured during the rainy season (July; 41 samples) and post-rainy season (October; 26 samples). Our results show that Ca2 + and Mg2 + were the dominant cations (55.87-98.52%), and HCO3- was the dominant anion (63.63-92.87%). The combined concentrations of Ca2 + and Mg2 + commonly exceeded the equivalent concentration of HCO3-, with calculated [Ca2 + + Mg2 +]/[HCO3-] equivalent ratios of 1.09-2.12. The mean measured groundwater δ13CDIC value (- 11.38‰) was higher than that expected for carbonate dissolution mediated solely by carbonic acid (- 11.5‰), and the strong positive correlation of these values with [SO42 - + NO3-]/HCO3- showed that additional SO42 - and NO3- were required to compensate for this cation excess. Nitric and sulfuric acids are, therefore, suggested to have acted as the additional proton-promoted weathering agents of carbonate in the region, alongside carbonic acid. The mean contribution of atmospheric/pedospheric CO2 to the total aquatic HCO3- decreased by 15.67% (rainy season) and 14.17% (post-rainy season) due to the contributions made by these acids. The annual mean deficit of soil CO2 uptake by carbonate weathering across the study area was 14.92%, which suggests that previous workers may have overestimated the absorption of CO2 by carbonate weathering in other karstic areas worldwide.

  7. Kinetics of Acid-Catalyzed Dehydration of Cyclic Hemiacetals in Organic Aerosol Particles in Equilibrium with Nitric Acid Vapor.

    Science.gov (United States)

    Ranney, April P; Ziemann, Paul J

    2016-04-28

    Previous studies have shown that 1,4-hydroxycarbonyls, which are often major products of the atmospheric oxidation of hydrocarbons, can undergo acid-catalyzed cyclization and dehydration in aerosol particles to form highly reactive unsaturated dihydrofurans. In this study the kinetics of dehydration of cyclic hemiacetals, the rate-limiting step in this process, was investigated in a series of environmental chamber experiments in which secondary organic aerosol (SOA) containing cyclic hemiacetals was formed from the reaction of n-pentadecane with OH radicals in dry air in the presence of HNO3. A particle beam mass spectrometer was used to monitor the formation and dehydration of cyclic hemiacetals in real time, and SOA and HNO3 were quantified in filter samples by gravimetric analysis and ion chromatography. Measured dehydration rate constants increased linearly with increasing concentration of HNO3 in the gas phase and in SOA, corresponding to catalytic rate constants of 0.27 h(-1) ppmv(-1) and 7.0 h(-1) M(-1), respectively. The measured Henry's law constant for partitioning of HNO3 into SOA was 3.7 × 10(4) M atm(-1), ∼25% of the value for dissolution into water, and the acid dissociation constant was estimated to be water. The results indicate that HNO3 was only weakly dissociated in the SOA and that dehydration of cyclic hemiacetals was catalyzed by molecular HNO3 rather than by H(+). The Henry's law constant and kinetics relationships measured here can be used to improve mechanisms and models of SOA formation from the oxidation of hydrocarbons in dry air in the presence of NOx, which are conditions commonly used in laboratory studies. The fate of cyclic hemiacetals in the atmosphere, where the effects of higher relative humidity, organic/aqueous phase separation, and acid catalysis by molecular H2SO4 and/or H(+) are likely to be important, is discussed.

  8. A-train CALIOP and MLS observations of early winter antarctic polar stratospheric clouds and nitric acid in 2008

    Directory of Open Access Journals (Sweden)

    A. Lambert

    2011-10-01

    Full Text Available A-train Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP and Microwave Limb Sounder (MLS observations are used to investigate the development of polar stratospheric clouds (PSCs and the gas phase nitric acid distribution in the early 2008 Antarctic winter. Observational evidence of gravity-wave activity is provided by Atmospheric Infrared Sounder (AIRS radiances and infrared spectroscopic detection of nitric acid trihydrate (NAT in PSCs is obtained from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS. Goddard Earth Observing System Data Assimilation System (GEOS-5 DAS analyses are used to derive Lagrangian trajectories and to determine temperature-time histories of air parcels. We use CALIOP backscatter and depolarization measurements to classify PSCs and the MLS measurements to determine the corresponding gas phase HNO3 as a function of temperature. For liquid PSCs the uptake of HNO3 follows the theoretical equilibrium curve for supercooled ternary solutions (STS, but at temperatures about 1 K lower as determined from GEOS-5. In the presence of solid phase PSCs, above the ice frost-point, the HNO3 depletion occurs over a wider range of temperatures (+2 to −7 K distributed about the NAT equilibrium curve. Rapid gas phase HNO3 depletion is first seen by MLS from from 23–25 May 2008, consisting of a decrease in the volume mixing ratio (parts per billion by volume from 14 ppbv to 7 ppbv on the 46–32 hPa (hectopascal pressure levels and accompanied by a 2–3 ppbv increase by renitrification at the 68 hPa pressure level. Temperature-time histories of air parcels demonstrate that the depleted HNO3 region is more clearly correlated with prior low temperature exposure of a few kelvin above the frost-point than with either the region bounded by the NAT existence temperature threshold or the region of minimum temperatures. From the combined data we infer the

  9. A-train CALIOP and MLS observations of early winter Antarctic polar stratospheric clouds and nitric acid in 2008

    Directory of Open Access Journals (Sweden)

    A. Lambert

    2012-03-01

    Full Text Available A-train Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP and Microwave Limb Sounder (MLS observations are used to investigate the development of polar stratospheric clouds (PSCs and the gas-phase nitric acid distribution in the early 2008 Antarctic winter. Observational evidence of gravity-wave activity is provided by Atmospheric Infrared Sounder (AIRS radiances and infrared spectroscopic detection of nitric acid trihydrate (NAT in PSCs is obtained from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS. Goddard Earth Observing System Data Assimilation System (GEOS-5 DAS analyses are used to derive Lagrangian trajectories and to determine temperature-time histories of air parcels. We use CALIOP backscatter and depolarization measurements to classify PSCs and the MLS measurements to determine the corresponding gas-phase HNO3 as a function of temperature. For liquid PSCs the uptake of HNO3 follows the theoretical equilibrium curve for supercooled ternary solutions (STS, but at temperatures about 1 K lower as determined from GEOS-5. In the presence of solid phase PSCs, above the ice frost-point, the HNO3 depletion occurs over a wider range of temperatures (+2 to −7 K distributed about the NAT equilibrium curve. Rapid gas-phase HNO3 depletion is first seen by MLS from from 23–25 May 2008, consisting of a decrease in the volume mixing ratio from 14 ppbv (parts per billion by volume to 7 ppbv on the 46–32 hPa (hectopascal pressure levels and accompanied by a 2–3 ppbv increase by renitrification at the 68 hPa pressure level. The observed region of depleted HNO3 is substantially smaller than the region bounded by the NAT existence temperature threshold. Temperature-time histories of air parcels demonstrate that the depletion is more clearly correlated with prior exposure to temperatures a few kelvin above the frost-point. From the combined data we infer the presence

  10. Gibberellic acid alleviates cadmium toxicity by reducing nitric oxide accumulation and expression of IRT1 in Arabidopsis thaliana

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiao Fang [State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310058 (China); Jiang, Tao [Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, College of Life Sciences, Zhejiang University, Hangzhou 310058 (China); Wang, Zhi Wei [State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310058 (China); Lei, Gui Jie [Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, College of Life Sciences, Zhejiang University, Hangzhou 310058 (China); Shi, Yuan Zhi [The Key Laboratory of Tea Chemical Engineering, Ministry of Agriculture, Yunqi Road 1, Hangzhou 310008 (China); Li, Gui Xin, E-mail: guixinli@zju.edu.cn [College of Agronomy and Biotechnology, Zhejiang University, Hangzhou 310058 (China); Zheng, Shao Jian [State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310058 (China); Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, College of Life Sciences, Zhejiang University, Hangzhou 310058 (China)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Cd reduces endogenous GA levels in Arabidopsis. Black-Right-Pointing-Pointer GA exogenous applied decreases Cd accumulation in plant. Black-Right-Pointing-Pointer GA suppresses the Cd-induced accumulation of NO. Black-Right-Pointing-Pointer Decreased NO level downregulates the expression of IRT1. Black-Right-Pointing-Pointer Suppressed IRT1 expression reduces Cd transport across plasma membrane. - Abstract: Gibberellic acid (GA) is involved in not only plant growth and development but also plant responses to abiotic stresses. Here it was found that treating the plants with GA concentrations from 0.1 to 5 {mu}M for 24 h had no obvious effect on root elongation in the absence of cadmium (Cd), whereas in the presence of Cd{sup 2+}, GA at 5 {mu}M improved root growth, reduced Cd content and lipid peroxidation in the roots, indicating that GA can partially alleviate Cd toxicity. Cd{sup 2+} increased nitric oxide (NO) accumulation in the roots, but GA remarkably reduced it, and suppressed the up-regulation of the expression of IRT1. In contrary, the beneficial effect of GA on alleviating Cd toxicity was not observed in an IRT1 knock-out mutant irt1, suggesting the involvement of IRT1 in Cd{sup 2+} absorption. Furthermore, the GA-induced reduction of NO and Cd content can also be partially reversed by the application of a NO donor (S-nitrosoglutathione [GSNO]). Taken all these together, the results showed that GA-alleviated Cd toxicity is mediated through the reduction of the Cd-dependent NO accumulation and expression of Cd{sup 2+} uptake related gene-IRT1 in Arabidopsis.

  11. Polymeric beads containing Cyanex 923 for actinide uptake from nitric acid medium: Studies with uranium and plutonium.

    Science.gov (United States)

    Gujar, R B; Lakshmi, D Shanthana; Figoli, A; Mohapatra, P K

    2013-08-30

    Conventional phase inversion technique has been successfully applied for the preparation of the solid phase extractant (SPE), Cyanex 923 loaded polymer beads. Two types of polymer beads prepared by blending Polyetherether ketone with card (PEEKWC)/DMF with 5% Cyanex 923 (SPE-I, av bead size: 900μm) and 10% Cyanex 923(SPE-II, av. bead size: 1100μm) were evaluated for the uptake of actinide ions. The polymer beads were characterized by various physical methods such as thermal analysis, surface morphology analysis by SEM, EDAX techniques, etc. The polymer beads were used for the experiments involving the uptake of both U(VI) and Pu(IV) at tracer scale and U(VI) at milli molar concentrations from nitric acid feeds. The actinide ion uptake studies involved kinetics of metal ion sorption, adsorption isotherms, and column studies. The metal sorption capacities for U(VI) at 3M HNO3 were found to be 38.8±1.9mg and 54.5±1.7mg per g of SPE-I and SPE-II, respectively. The sorption isotherm analysis with Langmuir, D-R and Freundlisch isotherms indicated chemisorption monolayer mechanism. Column studies were also carried out using 4.5mL bed volume columns containing about 0.4 and 0.45g of SPE-I and SPE-II, respectively. The breakthrough profiles were obtained for U(VI) and the elution profiles were obtained using 1M Na2CO3 as the eluent.

  12. Spatial and temporal distribution of ambient nitric acid and ammonia in the Athabasca Oil Sands Region, Alberta

    Directory of Open Access Journals (Sweden)

    Diane ALEXANDER

    2010-08-01

    Full Text Available Monthly average ambient concentrations of gaseous nitric acid (HNO3 and ammonia (NH3 were monitored at the Athabasca Oils Sands Region (AOSR, Alberta, Canada, between May 2005 and September 2008. Generally, concentrations of both pollutants were elevated and highly variable in space and time. The highest atmospheric concentrations occurred in the vicinity of the major mining and oil extraction activities of Fort Murray and Fort McKay. Maximum monthly average concentrations of HNO3 decreased from >6 μg m–3 2005 and 2006 to <4 μg m–3 in 2007 and 2008. While the HNO3 summer seasonal averages in 2005 and 2006 approached ~2 μg m–3 at some sites, in the subsequent summers and during winter seasons it rarely exceeded 1 μg m–3 and no clear differences between summer and winter occurred. Concentrations of NH3 were elevated during the entire study and frequently reached 6 μg m–3. Generally, NH3 stayed higher in summer than in winter; the summer seasonal averages often exceeded 4 μg m–3 while those for winter only on two occasions were above 3 μg m–3. In summer 2008, an expansion of the area with elevated NH3 levels was observed extending to remote locations. Ammonia is of a much higher concern from a perspective of possible biological effects, because of its potential for direct toxic effect on lichens and its contribution to the elevated N dry deposition with possible negative consequences for forests and other ecosystems.

  13. The partitioning of Nitric Acid between the gas phase and condensed phase of aqueous sulfate aerosols.

    Science.gov (United States)

    Mentel, T. F.; Folkers, M.; Sebald, H.; Wahner, A.

    2001-12-01

    The heterogeneous hydrolysis of N2O_5 on aqueous aerosol surfaces is an important source of atmospheric HNO3. We generated HNO3 by heterogeneous hydrolysis of N2O_5 on aqueous ammonium and sodium sulfate aerosols and studied its partitioning between the gas phase and the aerosol phase. The experiments were performed in the large aerosol chamber at the FZ-Jülich at several relative humidities. Gas phase processes and the composition of the aerosols were monitored on-line simultaneously by FTIR spectroscopy and by Steam Jet Aerosol Collection/Ion Chromatography. The aerosol size distributions in the range of 20 nm to 5 μ m were measured by differential electromobility classification and by aerodynamic particle sizing. In the presence of aqueous bisulfate and sulfate aerosols a fast heterogeneous formation HNO3 is observed. (The reaction probability of N2O_5 is about 0.02.) In the case of the acidic bisulfate aerosols the major fraction of heterogeneously formed HNO3 resides in the gas phase. For neutral sulfate aerosols a significant fraction of HNO3 is taken up by the condensed phase of the aerosols. This leads to a distinctive growth of the aerosol population during the heterogeneous hydrolysis of N2O_5, which is observable in the number size distribution as well as in IR extinction measurements. The observed partitioning of HNO3 between gas phase and aqueous aerosol phase can be quantitatively understood by a Pitzer based thermodynamic model for salt solutions of high ionic strength. The model calculations and low resolution FTIR spectroscopy demonstrate that protonation of sulfate to bisulfate is the driving force for the uptake of HNO3 in neutral sulfate aerosols.

  14. [Nitric oxide].

    Science.gov (United States)

    Rovira, I

    1995-01-01

    Nitric oxide was identified as the relaxing factor derived from the endothelium in 1987. Nitric oxide synthesis allows the vascular system to maintain a state of vasodilation, thereby regulating arterial pressure. Nitric oxide is also found in platelets, where it inhibits adhesion and aggregation; in the immune system, where it is responsible for the cytotoxic action of macrophages; and in the nervous system, where it acts as neurotransmitter. A deficit in endogenous synthesis of nitric oxide contributes to such conditions as essential arterial hypertension, pulmonary hypertension and heart disease. An excess of nitrous oxide induced by endotoxins and cytokinins, meanwhile, is believed to be responsible for hypotension in septic shock and for hyperdynamic circulatory state in cirrhosis of the liver. Nitric oxide has also been implicated in the rejection of transplanted organs and in cell damage after reperfusion. Inhaled nitrous oxide gas reduces pulmonary hypertension without triggering systemic hypotension in both experimental and clinical conditions. It also produces selective vasodilation when used to ventilate specific pulmonary areas, thereby improving the ventilation/perfusion ratio and, hence, oxygenation. Nitric oxide inhalation is effective in pulmonary hypertension-coincident with chronic obstructive lung disease, in persistent neonatal pulmonary hypertension and in pulmonary hypertension with congenital or acquired heart disease. Likewise, it reduces intrapulmonary shunt in acute respiratory failure and improves gas exchange. Under experimental conditions nitric oxide acts as a bronchodilator, although it seems to be less effective for this purpose in clinical use.(ABSTRACT TRUNCATED AT 250 WORDS)

  15. Management Observation Facility Fume Hoods

    Energy Technology Data Exchange (ETDEWEB)

    Sundsmo, V. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-05-17

    I reviewed all the hoods used for AS&I work in buildings 253, 254, and 255. All have had the minimum annual surveys conducted and some have had semi-annual reviews. The operating parameter labels are posted consistent to the right or above right (with the only exception the perchloric acid hood in 1734- on the left) which facilitates users knowing where to check for information. All hoods with sash doors (except the SE one in 1734 have a note on the Operating Parameters label to "keep sash doors closed". Again, this was checking consistency. No surveys were missed.

  16. Oxidation of Liquid Silicon in a Medium Scale Induction Furnace: Examination of the Fuming Rate and Fume Composition

    OpenAIRE

    Smith, Nicholas

    2012-01-01

    The aim of this work was to study the effect of flow rate on the fuming rate/silica flux of liquid silicon in order to gain a better understanding of the silica fuming during industrial ladle refining during silicon production. The formation of silica fume is the results when the liquid silicon is exposed to air. This silica fume has been shown to be a health hazard when breathed by plant workers and increased environmental regulations call for its elimination. This work is being done as part...

  17. Influence of gas-particle partitioning on ammonia and nitric acid fluxes above a deciduous forest in the Midwestern USA

    Science.gov (United States)

    Hansen, K.; Sørensen, L. L.; Hornsby, K. E.; Boegh, E.; Pryor, S. C.

    2013-12-01

    Quantifying the atmosphere-biosphere exchange of reactive nitrogen gasses (including ammonia (NH3) and nitric acid (HNO3)) is crucial to assessing the impact of anthropogenic activities on natural and semi-natural ecosystems. However, measuring the deposition of reactive nitrogen is challenging due to bi-directionality of the flux, and the dynamics of the chemical gas/aerosol equilibrium of NH3 and HNO3 (or other atmospheric acids) with aerosol-phase ammonium (NH4+) and nitrate (NO3-). NH3 and HNO3 are both very reactive and typically exhibit higher deposition velocities than aerosol NH4+. Therefore, the phase partitioning between gas and aerosol phases can have a significant effect on local budgets and atmospheric transport distances (Nemitz et al., Atmos. Chem. Phys., 2004). In this study, fluxes of NH3, HNO3 and carbon dioxide (CO2) along with size-resolved N-aerosol concentrations are measured above the deciduous forest, Morgan Monroe State Forest (MMSF) in south-central Indiana (39°53'N, 86°25'W) during a field campaign. Two relaxed eddy accumulation (REA) systems are used to measure fluxes and concentrations of NH3 and HNO3 at 44 m. The NH3 REA system operates based on wet effluent diffusion denuders with detection by florescence and half-hourly flux measurements are calculated. HNO3 REA system is based on gas capture on sodium chloride (NaCl) coated denuders with subsequent analysis by ion-chromatography, and the resulting fluxes have a resolution of 3-4 hours. CO2 fluxes are measured by eddy covariance using a closed-path Licor LI-7500, while two MSP MOUDI-110 impactors are used to measure the 24-hourly average inorganic and 48 hourly averaged organic ion concentrations in 11 size bins, respectively, just above the canopy level (28 m). The results of this field campaign are used to quantify the fluxes of NH3, HNO3, CO2 to/from the forest during the transition towards senescence, and to investigate process-level controls (e.g. the role of phase

  18. Improvement of oxygen-containing functional groups on olive stones activated carbon by ozone and nitric acid for heavy metals removal from aqueous phase.

    Science.gov (United States)

    Bohli, Thouraya; Ouederni, Abdelmottaleb

    2016-08-01

    Recently, modification of surface structure of activated carbons in order to improve their adsorption performance toward especial pollutants has gained great interest. Oxygen-containing functional groups have been devoted as the main responsible for heavy metal binding on the activated carbon surface; their introduction or enhancement needs specific modification and impregnation methods. In the present work, olive stones activated carbon (COSAC) undergoes surface modifications in gaseous phase using ozone (O3) and in liquid phase using nitric acid (HNO3). The activated carbon samples were characterized using N2 adsorption-desorption isotherm, SEM, pHpzc, FTIR, and Boehm titration. The activated carbon parent (COSAC) has a high surface area of 1194 m(2)/g and shows a predominantly microporous structure. Oxidation treatments with nitric acid and ozone show a decrease in both specific surface area and micropore volumes, whereas these acidic treatments have led to a fixation of high amount of surface oxygen functional groups, thus making the carbon surface more hydrophilic. Activated carbon samples were used as an adsorbent matrix for the removal of Co(II), Ni(II), and Cu(II) heavy metal ions from aqueous solutions. Adsorption isotherms were obtained at 30 °C, and the data are well fitted to the Redlich-Peterson and Langmuir equation. Results show that oxidized COSACs, especially COSAC(HNO3), are capable to remove more Co(II), Cu(II), and Ni(II) from aqueous solution. Nitric acid-oxidized olive stones activated carbon was tested in its ability to remove metal ions from binary systems and results show an important maximum adsorbed amount as compared to single systems.

  19. Hydrogen Peroxide and Nitric Oxide are Involved in Salicylic Acid-Induced Salvianolic Acid B Production in Salvia miltiorrhiza Cell Cultures

    Directory of Open Access Journals (Sweden)

    Hongbo Guo

    2014-05-01

    Full Text Available Hydrogen peroxide (H2O2 and nitric oxide (NO are key signaling molecules in cells whose levels are increased in response to various stimuli and are involved in plant secondary metabolite synthesis. In this paper, the roles of H2O2 and NO on salvianolic acid B (Sal B production in salicylic acid (SA-induced Salvia miltiorrhiza cell cultures were investigated. The results showed that H2O2 could be significantly elicited by SA, even though IMD (an inhibitor of NADPH oxidase or DMTU (a quencher of H2O2 were employed to inhibit or quench intracellular H2O2. These elicited H2O2 levels significantly increased NO production by 1.6- and 1.46 fold in IMD+SA and DMTU+SA treatments, respectively, and induced 4.58- and 4.85-fold Sal B accumulation, respectively. NO was also markedly elicited by SA, in which L-NNA (an inhibitor of NO synthase and cPTIO (a quencher of NO were used to inhibit or quench NO within cells, and the induced NO could significantly enhance H2O2 production by 1.92- and 1.37-fold in L-NNA+SA and cPTIO+SA treatments, respectively, and 3.27- and 1.50-fold for Sal B accumulation, respectively. These results indicate that elicitation of SA for either H2O2 or NO was independent, and the elicited H2O2 or NO could act independently or synergistically to induce Sal B accumulation in SA-elicited cells.

  20. Nitric oxide-releasing poly(lactic-co-glycolic acid-polyethylenimine nanoparticles for prolonged nitric oxide release, antibacterial efficacy, and in vivo wound healing activity

    Directory of Open Access Journals (Sweden)

    Nurhasni H

    2015-04-01

    Full Text Available Hasan Nurhasni,1 Jiafu Cao,1 Moonjeong Choi,1 Il Kim,2 Bok Luel Lee,1 Yunjin Jung,1 Jin-Wook Yoo11College of Pharmacy, Pusan National University, Busan, South Korea; 2Department of Polymer Science and Engineering, Pusan National University, Busan, South KoreaAbstract: Nitric oxide (NO-releasing nanoparticles (NPs have emerged as a wound healing enhancer and a novel antibacterial agent that can circumvent antibiotic resistance. However, the NO release from NPs over extended periods of time is still inadequate for clinical application. In this study, we developed NO-releasing poly(lactic-co-glycolic acid-polyethylenimine (PEI NPs (NO/PPNPs composed of poly(lactic-co-glycolic acid and PEI/diazeniumdiolate (PEI/NONOate for prolonged NO release, antibacterial efficacy, and wound healing activity. Successful preparation of PEI/NONOate was confirmed by proton nuclear magnetic resonance, Fourier transform infrared spectroscopy, and ultraviolet/visible spectrophotometry. NO/PPNPs were characterized by particle size, surface charge, and NO loading. The NO/PPNPs showed a prolonged NO release profile over 6 days without any burst release. The NO/PPNPs exhibited potent bactericidal efficacy against methicillin-resistant Staphylococcus aureus (MRSA and Pseudomonas aeruginosa concentration-dependently and showed the ability to bind on the surface of the bacteria. We also found that the NO released from the NO/PPNPs mediates bactericidal efficacy and is not toxic to healthy fibroblast cells. Furthermore, NO/PPNPs accelerated wound healing and epithelialization in a mouse model of a MRSA-infected wound. Therefore, our results suggest that the NO/PPNPs presented in this study could be a suitable approach for treating wounds and various skin infections.Keywords: nitric oxide-releasing nanoparticles, PLGA, PEI, antimicrobial, wound healing

  1. High effective silica fume alkali activator

    Indian Academy of Sciences (India)

    Vladimír Živica

    2004-04-01

    Growing demands on the engineering properties of cement based materials and the urgency to decrease unsuitable ecologic impact of Portland cement manufacturing represent significant motivation for the development of new cement corresponding to these aspects. One category represents prospective alkali activated cements. A significant factor influencing their properties is alkali activator used. In this paper we present a new high effective alkali activator prepared from silica fume and its effectiveness. According to the results obtained this activator seems to be more effective than currently used activators like natrium hydroxide, natrium carbonate, and water glass.

  2. Health hazards from inhalation of metal fumes

    Energy Technology Data Exchange (ETDEWEB)

    Piscator, M.

    1976-04-01

    Hazards to the health of workers exposed to metal fumes in high-temperature industrial operations (such as in shipyards) are detailed. After oxidation, the metals appear as submicron particles which are deposited in various parts of the respiratory system. Mixed exposures and a wide variety of symptoms may occur, depending on the type of metal and the intensity and duration of exposure. The major metal may not always be the most dangerous. Two of the most hazardous metals are lead and cadmium, the former being well recognized but still a problem, the latter often unrecognized but capable of causing severe, acute or chronic disease. (RFC)

  3. Improvements in the profiles and distributions of nitric acid and nitrogen dioxide with the LIMS version 6 dataset

    Directory of Open Access Journals (Sweden)

    E. Remsberg

    2010-05-01

    Full Text Available The quality of the Nimbus 7 Limb Infrared Monitor of the Stratosphere (LIMS nitric acid (HNO3 and nitrogen dioxide (NO2 profiles and distributions of 1978/1979 are described after their processing with an updated, Version 6 (V6 algorithm and subsequent archival in 2002. Estimates of the precision and accuracy of both of those species are developed and provided herein. The character of the V6 HNO3 profiles is relatively unchanged from that of the earlier LIMS Version 5 (V5 profiles, except in the upper stratosphere where the interfering effects of CO2 are accounted for better with V6. The accuracy of the retrieved V6 NO2 is also significantly better in the middle and upper stratosphere, due to improvements in its spectral line parameters and in the reduced biases for the accompanying V6 temperature and water vapor profiles. As a result of these important updates, there is better agreement with theoretical calculations for profiles of the HNO3/NO2 ratio, day-to-night NO2 ratio, and with estimates of the production of NO2 in the mesosphere and its descent to the upper stratosphere during polar night. In particular, the findings for middle and upper stratospheric NO2 should also be more compatible with those obtained from more recent satellite sensors because the effects of the spin-splitting of the NO2 lines are accounted for now with the LIMS V6 algorithm. The improved precisions and more frequent retrievals of the LIMS profiles along their orbit tracks provide for better continuity and detail in map analyses of these two species on pressure surfaces. It is judged that the chemical effects of the oxides of nitrogen on ozone can be studied quantitatively throughout the stratosphere with the LIMS V6 data.

  4. Critical evaluation of sequential leaching procedures for the determination of Ni and Mn species in welding fumes.

    Science.gov (United States)

    Berlinger, B; Náray, M; Sajó, I; Záray, G

    2009-06-01

    In this work, welding fume samples were collected in a welding plant, where corrosion-resistant steel and unalloyed structural steel were welded by gas metal arc welding (GMAW) and manual metal arc welding (MMAW) techniques. The welding fumes were sampled with a fixed-point sampling strategy applying Higgins-Dewell cyclones. The following solutions were used to dissolve the different species of Ni and Mn: ammonium citrate solution [1.7% (m/v) diammonium hydrogen citrate and 0.5% (m/v) citric acid monohydrate] for 'soluble' Ni, 50:1 methanol-bromine solution for metallic Ni, 0.01 M ammonium acetate for soluble Mn, 25% acetic acid for Mn(0) and Mn(2+) and 0.5% hydroxylammonium chloride in 25% acetic acid for Mn(3+) and Mn(4+). 'Insoluble' Ni and Mn contents of the samples were determined after microwave-assisted digestion with the mixture of concentrated (cc). HNO(3), cc. HCl and cc. HF. The sample solutions were analysed by inductively coupled plasma quadrupole mass spectrometry and inductively coupled plasma atomic emission spectrometry. The levels of total Ni and Mn measured in the workplace air were different because of significant differences of the fume generation rates and the distributions of the components in the welding fumes between the welding processes. For quality control of the leaching process, dissolution of the pure stoichiometric Mn and Ni compounds and their mixtures weighing was investigated using the optimized leaching conditions. The results showed the adequacy of the procedure for the pure metal compounds. Based on the extraction procedures, the predominant oxidation states of Ni and Mn proved to be very different depending on the welding techniques and type of the welded steels. The largest amount of Mn in GMAW fumes were found as insoluble Mn (46 and 35% in case of corrosion-resistant steel and unalloyed structural steel, respectively), while MMAW fumes contain mainly soluble Mn, Mn(0) and Mn(2+) (78%) and Mn(3+) and Mn(4+) (54%) in case of

  5. HYDRAULIC CONDUCTIVITY OF GCL WITH BENTONITE – SILICA FUME MATRIX

    Directory of Open Access Journals (Sweden)

    Mudimby Andal

    2012-12-01

    Full Text Available This paper presents the influence of partial replacement of bentonite by silica fume which is used in the manufacture of Geosynthetic Clay Liner (GCL. Geosynthetic Clay Liners consist bentonite (Sodium Based sandwiched between two geotextile. Benotinite, having low permeability imparts better hydraulic performance to the GCL to act as liner. In this investigation, an attempt has been made to study the hydraulic conductivity of GCL with modified Bentonite. The bentonite is partially replaced by silica fume, a waste product of ferroalloy industries. Silica fume reduces the cracking characteristics of bentonite on desiccation. The replacement levels varied from 0% to 50% at a gradual increment of 5%. The test results indicated that partial replacement of bentonite by silica fume did not affected the permeability of bentonite even at 30%. Beyond 45% replacement levels the bentonite- silica fume mixtures showed increased permeability. This increased permeability also well within permeability limits of liners 1×10-9 m/sec.

  6. HYDRAULIC CONDUCTIVITY OF GCL WITH BENTONITE - SILICA FUME MATRIX

    Directory of Open Access Journals (Sweden)

    M. Andal

    2012-01-01

    Full Text Available This paper presents the influence of partial replacement of bentonite by silica fume which is used in the manufacture of Geosynthetic Clay Liner (GCL. Geosynthetic Clay Liners consist bentonite (Sodium Based sandwiched between two geotextile. Benotinite, having low permeability imparts better hydraulic performance to the GCL to act as liner. In this investigation, an attempt has been made to study the hydraulic conductivity of GCL with modified Bentonite. The bentonite is partially replaced by silica fume, a waste product of ferroalloy industries. Silica fume reduces the cracking characteristics of bentonite on desiccation. The replacement levels varied from 0% to 50% at a gradual increment of 5%. The test results indicated that partial replacement of bentonite by silica fume did not affected the permeability of bentonite even at 30%. Beyond 45% replacement levels the bentonite- silica fume mixtures showed increased permeability. This increased permeability also well within permeability limits of liners 1×10-9m/sec.

  7. Genotoxicity of fumes from heated cooking oils produced in Taiwan.

    Science.gov (United States)

    Wu, P F; Chiang, T A; Ko, Y C; Lee, H

    1999-02-01

    Epidemiologic investigations of lung cancer among Taiwanese nonsmoking women have found that exposure to fumes from cooking oils may be an important risk factor. Fume samples from three different commercial cooking oils (lard, soybean, and peanut oils) often used in Taiwan for preparing Chinese meals were collected for genotoxicity analysis in SOS chromotest and sister chromatid exchange (SCE) assays. The induction factors of the SOS chromotest in Escherichia coli PQ 37 were dependent on the concentrations of lard and soybean cooking oil extracts without S9 mix. In addition, when CHO-K1 cells were exposed to condensates of cooking oil fumes for 12 h, SCEs showed a dose-related increase in extracts of lard and soybean oil fumes. This result provides experimental evidence and is in accordance with the findings of epidemiologic studies that women exposed to the emitted fumes of cooking oils are at an increase risk of contracting lung cancer. Copyright 1999 Academic Press.

  8. Formation of nitric oxide, ethyl nitrite and an oxathiolone derivative of caffeic acid in a mixture of saliva and white wine.

    Science.gov (United States)

    Takahama, Umeo; Tanaka, Mariko; Hirota, Sachiko

    2010-03-01

    Reactions of salivary nitrite with components of wine were studied using an acidic mixture of saliva and wine. The formation of nitric oxide (NO) in the stomach after drinking wine was observed. The formation of NO was also observed in the mixture (pH 3.6) of saliva and wine, which was prepared by washing the oral cavity with wine. A part of the NO formation in the stomach and the oral cavity was due to the reduction of salivary nitrite by caffeic and ferulic acids present in wine. Ethyl nitrite produced by the reaction of salivary nitrite and ethyl alcohol in wine also contributed to the formation of NO. In addition to the above reactions, caffeic acid in wine could be transformed to the oxathiolone derivative, which might have pharmacological functions. The results obtained in this study may help in understanding the effects of drinking wine on human health.

  9. Fabrication process for sintered mixed oxides soluble in nitric acid from nitrate solutions. [nuclear fuels]. Procede d'obtention d'oxydes mixtes frittes solubles dans l'acide nitrique a partir de solutions de nitrates

    Energy Technology Data Exchange (ETDEWEB)

    Bachelard, R.; Germanaz, P.

    1987-10-02

    Mixed oxide nuclear fuels are obtained by mixing the nitrate solutions, concentration, heat treatment for an intermediary mixed oxide containing U(VI) and Pu(IV or VI), calcination to obtain U/sub 3/O/sub 8/, reduction in U(IV) and Pu(IV), pelletizing, sintering and machining. Less wastes are produced and the fuel pellets are soluble in nitric acid.

  10. A Thermochemical Kinetic-Based Study of Ignition Delays for 2-Azidoethanamine-Red Fuming Nitric Acid Systems: 2-Azido-N-Methylethanamine (MMAZ) Vs. 2-Azido-N,N-Dimethylethanamine (DMAZ)

    Science.gov (United States)

    2014-01-01

    Staroverov, V. N.; Keith , T.; Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega...5 HC) B FORCH RDRL WML M ZOLTOSKI RDRL WML B J BRENNAN S BUNTE E BYRD J CIEZAK- JENKINS M HURLEY B RICE D TAYLOR

  11. 加快产业结构调整与建设大型硝酸装置的思考%Accelerate Industrial Restructure and Build Large Nitric Acid Plants

    Institute of Scientific and Technical Information of China (English)

    唐文骞; 杨同莲

    2012-01-01

    引入原料与资源量、能源量的概念,分析了各种硝酸生产方法中的吨酸比氨耗值和比能源值.通过产业结构调整的分析可知,双加压法硝酸具有无可争议的优势,该法应成为我国硝酸工业发展的主流工艺.同时指出建设大型或特大型双加压法硝酸装置在我国已具备设计、制造、运行的条件和经验,并将取得十分可观的经济效益.%By introducing the concept of feedstock, amount of resource and energy, the specific ammonia consumption per ton of nitric acid and the specific energy consumption per ton of nitric acid through different nitric acid production processes were analyzed. The result of specific energy consumption comparisons shows that the dual pressure process has the indisputable advantage against other processes. It should become the mainstream process in the development of nitric acid industry in China. The paper also pointed out that China has already the ability and experience in engineering design, manufacture and operation of large and super-large nitric acid plants adopting the dual pressure process and has obtained considerable economic benefits.

  12. Maintenance and Testing of Fume Cupboard

    Energy Technology Data Exchange (ETDEWEB)

    Hussein, Falah H.; Al-Dahhan, Wedad H.; Al-Zuhairi, Ali Jassim; Rodda, Kabrena E.; Yousif, Emad

    2017-01-01

    Scientists at universities across Iraq are actively working to report actual incidents and accidents occurring in their laboratories, as well as structural improvements made to improve safety and security, to raise awareness and encourage openness, leading to widespread adoption of robust Chemical Safety and Security (CSS) practices. This manuscript highlights the importance of periodic maintenance on fume cupboards, and is the fourth in a series of five case studies describing laboratory incidents, accidents, and laboratory improvements. In this study, we describe a situation in which the ventilation capacity of the fume cupboard in the undergraduate chemistry laboratories at Al-Nahrain University had decreased to an unacceptable level. The CSS Committee investigated and found the ducting system had been blocked by plastic sheets and dead birds. All the ducts have since been cleaned, and four extra ventilation fans have been installed to further increase ventilation capacity. By openly sharing what happened along with the lessons learned from the accident, we hope to minimize the possibility of another researcher being injured in a similar incident in the future.

  13. Pimaradienoic Acid Inhibits Carrageenan-Induced Inflammatory Leukocyte Recruitment and Edema in Mice: Inhibition of Oxidative Stress, Nitric Oxide and Cytokine Production.

    Directory of Open Access Journals (Sweden)

    Sandra S Mizokami

    Full Text Available Pimaradienoic acid (PA; ent-pimara-8(14,15-dien-19-oic acid is a pimarane diterpene found in plants such as Vigueira arenaria Baker (Asteraceae in the Brazilian savannas. Although there is evidence on the analgesic and in vitro inhibition of inflammatory signaling pathways, and paw edema by PA, its anti-inflammatory effect deserves further investigation. Thus, the objective of present study was to investigate the anti-inflammatory effect of PA in carrageenan-induced peritoneal and paw inflammation in mice. Firstly, we assessed the effect of PA in carrageenan-induced leukocyte recruitment in the peritoneal cavity and paw edema and myeloperoxidase activity. Next, we investigated the mechanisms involved in the anti-inflammatory effect of PA. The effect of PA on carrageenan-induced oxidative stress in the paw skin and peritoneal cavity was assessed. We also tested the effect of PA on nitric oxide, superoxide anion, and inflammatory cytokine production in the peritoneal cavity. PA inhibited carrageenan-induced recruitment of total leukocytes and neutrophils to the peritoneal cavity in a dose-dependent manner. PA also inhibited carrageenan-induced paw edema and myeloperoxidase activity in the paw skin. The anti-inflammatory mechanism of PA depended on maintaining paw skin antioxidant activity as observed by the levels of reduced glutathione, ability to scavenge the ABTS cation and reduce iron as well as by the inhibition of superoxide anion and nitric oxide production in the peritoneal cavity. Furthermore, PA inhibited carrageenan-induced peritoneal production of inflammatory cytokines TNF-α and IL-1β. PA presents prominent anti-inflammatory effect in carrageenan-induced inflammation by reducing oxidative stress, nitric oxide, and cytokine production. Therefore, it seems to be a promising anti-inflammatory molecule that merits further investigation.

  14. [Analysis on oil fume particles in catering industry cooking emission].

    Science.gov (United States)

    Tan, De-Sheng; Kuang, Yuan-Cheng; Liu, Xin; Dai, Fei-Hong

    2012-06-01

    By measuring the particulate matter of oil fume which is over 10 microm or below 10 microm separately and using microradiography and Electrical Low Pressure Impactor (ELPI), it is found out the distributing characteristic of oil fume particles in catering industry cooking emission. The result shows that the diameter of the oil fume particles which was sedimentated in the kitchen is between 10-400 microm, the concentration peak value is between 10-100 microm. The diameter of oil fume aerosol is mostly smaller than 1 microm, while the concentration peak value is between 0.063-0.109 microm. In addition, the mass concentration peak value is between 6.560-9.990 microm. Through the analysis to the physical characteristics of oil fume from catering industry cooking emissions, the eigenvalue of the oil fume has been found and the feature matter for monitoring the oil fume has been discovered to provide a reasonable standard for controlling and monitoring the catering industry cooking emission.

  15. Bitumen fume-induced gene expression profile in rat lung.

    Science.gov (United States)

    Gate, Laurent; Langlais, Cristina; Micillino, Jean-Claude; Nunge, Hervé; Bottin, Marie-Claire; Wrobel, Richard; Binet, Stéphane

    2006-08-15

    Exposure to bitumen fumes during paving and roofing activities may represent an occupational health risk. To date, most of the studies performed on the biological effect of asphalt fumes have been done with regard to their content in carcinogenic polycyclic aromatic hydrocarbons (PAH). In order to gain an additional insight into the mechanisms of action of bitumen fumes, we studied their pulmonary effects in rodents following inhalation using the microarray technology. Fisher 344 rats were exposed for 5 days, 6 h/day to bitumen fumes generated at road paving temperature (170 degrees C) using a nose-only exposition device. With the intention of studying the early transcriptional events induced by asphalt fumes, lung tissues were collected immediately following exposure and gene expression profiles in control and exposed rats were determined by using oligonucleotide microarrays. Data analysis revealed that genes involved in lung inflammatory response as well as genes associated with PAH metabolization and detoxification were highly expressed in bitumen-exposed animals. In addition, the expression of genes related to elastase activity and its inhibition which are associated with emphysema was also modulated. More interestingly genes coding for monoamine oxidases A and B involved in the metabolism of neurotransmitters and xenobiotics were downregulated in exposed rats. Altogether, these data give additional information concerning the bitumen fumes biological effects and would allow to better review the health effects of occupational asphalt fumes exposure.

  16. Effects of abscisic acid and nitric oxide on trap formation and trapping of nematodes by the fungus Drechslerella stenobrocha AS6.1.

    Science.gov (United States)

    Xu, Ling-Ling; Lai, Yi-Ling; Wang, Lin; Liu, Xing-Zhong

    2011-02-01

    The in vitro effects of abscisic acid (ABA) and nitric oxide (NO) on the nematode-trapping fungus Drechslerella stenobrocha AS6.1 were examined. The average number of traps (constricting rings) per colony and the percentage of nematodes (Caenorhabditis elegans) trapped were greatly increased by addition of ABA but greatly suppressed by addition of sodium nitroprusside (SNP, an NO donor) to corn meal agar. The suppressive effect of SNP was not negated by addition of an NO synthase competitive inhibitor (l-naphthylacetic acid, L-NNA) or an NO-specific scavenger [2-(4-carboxyphenyl)-4,4, 5,5-tetramethylimidazoline-1-oxyl-3-oxide, cPTIO]. When added without SNP, however, L-NNA and cPTIO caused moderate increases in trap number and trapping. The results indicate that the trap formation and nematode-trapping ability of D. stenobrocha were enhanced by ABA but decreased by exogenous NO.

  17. Comparative effects of sulfuric and nitric acid rain on litter decomposition and soil microbial community in subtropical plantation of Yangtze River Delta region.

    Science.gov (United States)

    Liu, Xin; Zhang, Bo; Zhao, Wenrui; Wang, Ling; Xie, Dejin; Huo, Wentong; Wu, Yanwen; Zhang, Jinchi

    2017-12-01

    Acid rain is mainly caused by dissolution of sulfur dioxide and nitrogen oxides in the atmosphere, and has a significant negative effect on ecosystems. The relative composition of acid rain is changing gradually from sulfuric acid rain (SAR) to nitric acid rain (NAR) with the rapidly growing amount of nitrogen deposition. In this study, we investigated the impact of simulated SAR and NAR on litter decomposition and the soil microbial community over four seasons since March 2015. Results first showed that the effects of acid rain on litter decomposition and soil microbial were positive in the early period of the experiment, except for SAR on soil microbes. Second, soil pH with NAR decreased more rapidly with the amount of acid rain increased in summer than with SAR treatments. Only strongly acid rain (both SAR and NAR) was capable of depressing litter decomposition and its inhibitory effect was stronger on leaf than on fine root litter. Meanwhile, NAR had a higher inhibitory effect on litter decomposition than SAR. Third, in summer, autumn and winter, PLFAs were negatively impacted by the increased acidity level resulting from both SAR and NAR. However, higher acidity level of NAR (pH=2.5) had the strongest inhibitory impact on soil microbial activity, especially in summer. In addition, Gram-negative bacteria (cy19:0) and fungi (18:1ω9) were more sensitive to both SAR and NAR, and actinomycetes was more sensitive to SAR intensity. Finally, soil total carbon, total nitrogen and pH were the most important soil property factors affecting soil microbial activity, and high microbial indices (fungi/bacteria) with high soil pH. Our results suggest that the ratio of SO4(2-) to NO3(-) in acid rain is an important factor which could affect litter decomposition and soil microbial in subtropical forest of China. Copyright © 2017. Published by Elsevier B.V.

  18. Welding-fume-induced transmission loss in tapered optical fibers

    Science.gov (United States)

    Yi, Ji-Haeng

    2015-09-01

    This paper presents a method for sensing welding fumes in real time. This method is based on the results of nanoparticle-induced optical-fiber loss experiments that show that the losses are determined by the nanoparticle density and the taper waist. The tapered fiber is obtained by applying heat radiated from hot quartz, and monitoring is done in real time. First, the durability of the tapered fiber during the welding process is proven. Then, the loss is categorized by using the sizes of welding fume particles. The sensitivity to welding fumes increases with increasing size of the particles; consequently, the dimension of the taper waist decreases.

  19. Recovery of nitric acid and hydrofluoric acid from passivation solution of steels by diffusion dialysis%扩散渗析法回收不锈钢钝化液中HNO3和HF

    Institute of Scientific and Technical Information of China (English)

    王昆; 刘飞; 邢卫红

    2012-01-01

    Recovery of nitric acid and hydrofluoric acid produced in passivation process of steels by diffusion dialysis was studied. The recovery rates of one-component nitric acid and hydrofluoric acid were investigated. Effects of flow rate, temperature and concentration of iron ion on mixed acid solution diffusion dialysis were analyzed. The results showed that it was an effective way to separate mixed acid solution by diffusion dialysis. The recovery rate decreased with the increase of the flow rate. Increasing the temperature was beneficial to the acid diffusion through the membrane. Under the operating condition of flow rate of 170 mL/h at normal temperature, the retention rate of iron ions was more than 95% ,the recovery rate of total acid was more than 85% with nitric acid 90% and hydrofluoric acid 40%.%采用扩散渗析法回收不锈钢钝化废液中的HNO3和HF,考察单组分酸、混合酸的回收率和废酸流量、温度、金属离子浓度等因素对扩散渗析过程的影响.结果表明:扩散渗析过程中HNO3回收率大于HF ;酸回收率随着废酸流量增大而减小 ;温度升高有利于酸扩散透过膜 ;Fe3+浓度对截留率影响不大.对于不锈钢钝化废酸液体系,扩散渗析对于H+和Fe3+具有良好的分离效果,常温下,废酸流量为170 mL/h时,总酸回收率为85%,其中HNO3回收率为90%,HF回收率为40%,Fe3+的截留率达到95%以上.

  20. Hydroxycarboxylic acids and salts

    Energy Technology Data Exchange (ETDEWEB)

    Kiely, Donald E; Hash, Kirk R; Kramer-Presta, Kylie; Smith, Tyler N

    2015-02-24

    Compositions which inhibit corrosion and alter the physical properties of concrete (admixtures) are prepared from salt mixtures of hydroxycarboxylic acids, carboxylic acids, and nitric acid. The salt mixtures are prepared by neutralizing acid product mixtures from the oxidation of polyols using nitric acid and oxygen as the oxidizing agents. Nitric acid is removed from the hydroxycarboxylic acids by evaporation and diffusion dialysis.

  1. Adsorption of sulfur dioxide by active carbon treated by nitric acid: I. Effect of the treatment on adsorption of SO{sub 2} and extractability of the acid formed

    Energy Technology Data Exchange (ETDEWEB)

    Lisovskii, A.; Semiat, R.; Aharoni, C. [Technion-Israle Institute of Technology, Haifa (Israel). Chemical Engineering Dept.

    1997-12-31

    Activated carbon is used as an adsorbent in flue gas cleaning. The process of adsorptive-catalytic cleaning of gas from sulfur dioxide using active carbon, treated by concentrated nitric acid, was studied. After oxidative treatment the acidity of the carbon increases and the basicity decreases. This results in an increase of the SO{sub 2} adsorption and its oxidation to SO{sub 3}, and in weaker retention of the sulfuric acid formed. This facilitates the removal of H{sub 2}SO{sub 4} by washing of the carbon and allows to obtain a more concentrated acid. The efficiency of the treated carbon is also higher in the process of SO{sub 2} removal from a gas similar in composition to stack gases. 13 refs., 1 fig., 7 tabs.

  2. Enrichment of nitrogen-15 by nitrox system. Part 1: countercorrent column of aqueous nitric acid and nitrogen oxides in gaseous phase; Enriquecimento de nitrogenio-15 pelo sistema Nitrox. Parte 1: coluna de contracorrente entre solucao de acido nitrico e oxidos de nitrogenio na fase gasosa

    Energy Technology Data Exchange (ETDEWEB)

    Ducatti, Carlos [UNESP, Botucatu, SP (Brazil). Inst. de Biociencias. Dept. de Fisica e Biofisica; Bonassi, Jose A.; Matsui, Eichii [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil)

    1997-12-01

    In this paper described the operational mode of countercurrent column of aqueous nitric acid and nitrogen oxides (Nitrox System) for the production of nitric acid in the concentration of 5% atoms of {sup 15} N in laboratory. (author). 8 refs., 2 tabs., 1 fig.

  3. Americium(III) oxidation by copper(III) periodate in nitric acid solution as compared with the action of Bi(V) compounds of sodium, lithium, and potassium

    Energy Technology Data Exchange (ETDEWEB)

    Sinkov, Sergey I.; Lumetta, Gregg J. [Pacific Northwest National Laboratory, Radiochemical Processing Lab., Richland, WA (United States)

    2015-07-01

    The oxidative action of a Cu(III) periodate compound toward Am(III) in nitric acid was studied. The extent of oxidation of Am(III) to Am(VI) was investigated using a constant initial Cu(III)-to-Am(III) molar ratio of 10:1 and varying nitric acid concentrations from 0.25 to 3.5 mol/L. From 0.25 to 3 mol/L HNO3, more than 98% of the Am(III) was oxidized to Am(VI); however, at 3.5 mol/L HNO{sub 3}, the conversion to Am(VI) was only 80%. Increasing the Cu(III)-to-Am(III) molar ratio to 20:1 in 3.5 mol/L HNO{sub 3} resulted in 98% conversion to Am(VI). For comparison, oxidation of Am(III) with NaBiO{sub 3} was studied at 3.5 mol/L HNO{sub 3} and the same stoichiometric excess of Bi(V) oxidant over Am(III) (stoichiometric ratio of 3.33:1). With NaBiO{sub 3}, the extent of Am(III) conversion to Am(VI) was only 19%, while with the Cu(III) compound this value was found to be about 4 times higher under otherwise identical conditions. Similar results were obtained with other Bi(V) salts. These results show that the Cu(III) periodate compound is a superior oxidant to NaBiO{sub 3}, yielding rapid conversion to Am(VI) in a homogeneous acidic solution, and is, therefore, an excellent candidate for further development of Am separation systems.

  4. A theoretical study of nitric oxide adsorption and dissociation on copper-exchanged zeolites SSZ-13 and SAPO-34: the impact of framework acid-base properties.

    Science.gov (United States)

    Uzunova, Ellie L; Mikosch, Hans

    2016-04-28

    The adsorption of nitric oxide as dinitrosyls and the deNOx proton-mediated reaction mechanism are assessed using electronic structure methods and transition state theory. Dinitrosyls bind to copper cations either via a N-atom or via an O-atom, with N-binding being more stable. In their ground states, dinitrosyls reach a planar configuration with the metal cation. The two nitric oxide molecules are kept together in O-bonded dinitrosyls by the N-N bond and the adsorption complex obtains a cyclic planar structure, while N-bonded dinitrosyls have out-of-plane conformations with low energy barriers. An asymmetric structure ZCu(ON)(NO) with one N-bonded nitrosyl and the other O-bonded is of the lowest stability. The cyclic hyponitrite ZCu(ON)2 adsorption complex undergoes O-N bond breaking upon protonation of one oxygen atom and this lowers the energy barrier of the first reaction step of nitric oxide dissociation to yield N2O and a hydroxylated copper site ZCu(OH) by 45 kJ mol(-1) for Cu-SAPO-34 and by 46 kJ mol(-1) for Cu-SSZ-13. The more stable N-bonded dinitrosyl ZCu(NO)2 provides less favorable reaction which passes through the asymmetric ZCu(ON)(NO) intermediate structure. Brønsted acid sites facilitate the reversal of one nitrosyl group. The role of proton transfer from a Brønsted acid site to dinitrosyls is not limited to the initial step of facilitating the N-O bond cleavage, but it also contributes to the stabilization of intermediate oxygen species formed at the copper site as hydroxide ZCu(OH) and hydroperoxide, ZCuOOH. Without protonation, the unstable ZCuO intermediate causes structural deformation with strongly lengthened T-O bonds in the framework. The rate determining step is N2O decomposition to N2 and O2, whether starting with a ZCu(NO)2 or a ZCu(ON)2 adsorption complex, and Cu-SSZ-13 has a clear advantage with an energy barrier of 195 kJ mol(-1)vs. 265 kJ mol(-1) for Cu-SAPO-34. In the final step the Brønsted acid site is restored by proton

  5. Peripheral neuropathy following intentional inhalation of naphtha fumes.

    OpenAIRE

    Tenenbein, M; deGroot, W.; Rajani, K R

    1984-01-01

    Two adolescent native Canadians who presented with peripheral neuropathy secondary to the abuse of volatile hydrocarbons are described. They were initially thought to have been sniffing leaded gasoline fumes, but public health investigation revealed that they had been sniffing naphtha fumes. Naphtha contains a significant amount of n-hexane, a known inducer of neuropathy. Nerve conduction studies and nerve biopsy confirmed the diagnosis of naphtha abuse. These cases emphasize the need to spec...

  6. Peripheral neuropathy following intentional inhalation of naphtha fumes.

    Science.gov (United States)

    Tenenbein, M; deGroot, W; Rajani, K R

    1984-11-01

    Two adolescent native Canadians who presented with peripheral neuropathy secondary to the abuse of volatile hydrocarbons are described. They were initially thought to have been sniffing leaded gasoline fumes, but public health investigation revealed that they had been sniffing naphtha fumes. Naphtha contains a significant amount of n-hexane, a known inducer of neuropathy. Nerve conduction studies and nerve biopsy confirmed the diagnosis of naphtha abuse. These cases emphasize the need to specifically identify the formulation of hydrocarbons being abused.

  7. Anatomical indications of fume resistance in certain woody plants

    Energy Technology Data Exchange (ETDEWEB)

    Ninova, D.

    1970-01-01

    An attempt is made to describe studies on seven species of fruit and forest trees close to or far from a Bulgarian factory emitting fumes containing S. The most resistant species (Quercus borealis, Gleditsia triacanthos, Morus alba) had the smallest stomata and the greatest number of stomata per unit leaf area. Changes observed in leaf anatomy as a result of exposure to the fumes were: decreased leaf aeration, elongated palisade cells, thicker cuticles, and more stomata.

  8. Decreasing biotoxicity of fume particles produced in welding process.

    Science.gov (United States)

    Yu, Kuei-Min; Topham, Nathan; Wang, Jun; Kalivoda, Mark; Tseng, Yiider; Wu, Chang-Yu; Lee, Wen-Jhy; Cho, Kuk

    2011-01-30

    Welding fumes contain heavy metals, such as chromium, manganese, and nickel, which cause respiratory diseases and cancer. In this study, a SiO(2) precursor was evaluated as an additive to the shielding gas in an arc welding process to reduce the biotoxicity caused by welding fume particles. Transmission electron micrographic images show that SiO(2) coats on the surface of welding fume particles and promotes particle agglomeration. Energy dispersive X-ray spectroscopy further shows that the relative amount of silicon in these SiO(2)-coated agglomerates is higher than in baseline agglomerates. In addition, Escherichia coli (E. coli) exposed to different concentrations of pure SiO(2) particles generated from the arc welding process exhibits similar responses, suggesting that SiO(2) does not contribute to welding fume particle toxicity. The trend of E. coli growth in different concentrations of baseline welding fume particle shows the most significant inhibition occurs in higher exposure concentrations. The 50% lethal logarithmic concentrations for E. coli in arc welding particles of baseline, 2%, and 4.2% SiO(2) precursor additives were 823, 1605, and 1800 mg/L, respectively. Taken together, these results suggest that using SiO(2) precursors as an additive to arc welding shielding gas can effectively reduce the biotoxicity of welding fume.

  9. Required response time for variable air volume fume hood controllers.

    Science.gov (United States)

    Ekberg, L E; Melin, J

    2000-03-01

    This paper describes results from tests made with the aim of investigating how quickly the exhaust air flow rate through fume hoods needs to be controlled in order to prevent contaminants from leaking out of the fume hood and putting the safety of the laboratory personnel at risk. The measurements were made on a laboratory fume hood in a chemical laboratory. There were no other fume hoods in the laboratory, and the measurements were made without interference from persons entering or leaving the laboratory or walking about in it. A tracer gas method was used with the concentration of dinitrogen oxide (N(2)O) being recorded by a Foxboro Miran 101 infra-red gas analyser. In parallel with the tracer gas measurements, the air velocity through the face opening was also measured, as was the control signal to the damper controlling the air flow rate. The measurements show an increased outward leakage of tracer gas from the fume hood if the air flow rate is not re-established within 1-2 s after the sash is opened. If the delay exceeds 3 s the safety function is temporarily defeated. The measurements were made under virtually ideal conditions. Under more typical conditions, the fume hood could be exposed to various other external perturbations, which means that the control system should re-establish the correct exhaust flow more quickly than indicated by the measurement results obtained under these almost ideal conditions.

  10. Design considerations for fume hoods for process plants.

    Science.gov (United States)

    Goodfellow, H D; Bender, M

    1980-07-01

    Proper design of fume hoods is a necessary requisite for a clean working environment for many industrial processes. Until recently, the design of these hoods has been rather a trial and error approach and not based on sound engineering design principles. Hatch Associates have developed and applied new techniques to establish hood parameters for different industrail processes. The paper reviews the developed techniques and illustrates practical application of these techniques to the solving of difficult and comples fume hood design and operating performance problems. The scope of the paper covers the following subject areas: definitions and general considerations: evaluation of volume and heat flow rates for emission sources; local capture of process emissions; remote capture of process emissions and case studies of fume hood applications. The purpose of the paper is to detail a coherent approach in the analysis of emission problems which will result in the development of an efficient design of a fume capture hood. An efficient fume hood can provide a safe working place as well as a clean external environment. Although the techniques can be applied to smaller sources, the case studies which will be examined will be for fume hoods in the flow design range of 50 000 CFM to +1 000 000 CFM.

  11. Insights into the mechanism of extraction of uranium (VI) from nitric acid solution into an ionic liquid by using tri-n-butyl phosphate.

    Science.gov (United States)

    Gaillard, Dr Clotilde; Boltoeva, Maria; Billard, Isabelle; Georg, Sylvia; Mazan, Valérie; Ouadi, Ali; Ternova, Dariia; Hennig, Christoph

    2015-08-24

    We present new results on the liquid-liquid extraction of uranium (VI) from a nitric acid aqueous phase into a tri-n-butyl phosphate/1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (TBP/[C4 mim][Tf2 N]) phase. The individual solubilities of the ionic-liquid ions in the upper part of the biphasic system are measured over the whole acidic range and as a function of the TBP concentration. New insights into the extraction mechanism are obtained through the in situ characterization of the extracted uranyl complexes by coupling UV/Vis and extended X-ray absorption fine structure (EXAFS) spectroscopy. We propose a chemical model to explain uranium (VI) extraction that describes the data through a fit of the uranyl distribution ratio DU . In this model, at low acid concentrations uranium (VI) is extracted as the cationic complex [UO2 (TBP)2 ](2+) , by an exchange with one proton and one C4 mim(+) . At high acid concentrations, the extraction proceeds through a cationic exchange between [UO2 (NO3 )(HNO3 )(TBP)2 ](+) and one C4 mim(+) . As a consequence of this mechanism, the variation of DU as a function of TBP concentration depends on the C4 mim(+) concentration in the aqueous phase. This explains why noninteger values are often derived by analysis of DU versus [TBP] plots to determine the number of TBP molecules involved in the extraction of uranyl in an ionic-liquid phase.

  12. The three dimensional distribution of chromium and nickel alloy welding fumes.

    Directory of Open Access Journals (Sweden)

    Takeoka,Kiyoshi

    1991-08-01

    Full Text Available In the present study, the fumes generated from manual metal arc (MMA and submerged metal arc (SMA welding of low temperature service steel, and the chromium and nickel percentages in these fumes, were measured at various horizontal distances and vertical heights from the arc in order to obtain a three dimensional distribution. The MMA welding fume concentrations were significantly higher than the SMA welding fume concentrations. The highest fume concentration on the horizontal was shown in the fumes collected directly above the arc. The fume concentration vertically was highest at 50 cm height and reduced by half at 150 cm height. The fume concentration at 250 cm height was scarcely different from that at 150 cm height. The distribution of the chromium concentration vertically was analogous to the fume concentration, and a statistically significant difference in the chromium percentages was not found at the different heights. The nickel concentrations were not statistically significant within the welding processes, but the nickel percentages in the SMA welding fumes were statistically higher than in the MMA welding fumes. The highest nickel concentration on the horizontal was found in the fumes collected directly above the arc. The highest nickel concentration vertically showed in the fume samples collected at 50 cm height, but the greater the height the larger the nickel percentage in the fumes.

  13. Nitric Acid Particles in Cold Thick Ice Clouds Observed at Global Scale: Link with Lightning, Temperature, and Upper Tropospheric Water Vapor

    Science.gov (United States)

    Chepfer, H.; Minnis, P.; Dubuisson, P.; Chiriaco, M.; Sun-Mack, S.; Riviere, E. D.

    2007-01-01

    Signatures of nitric acid particles (NAP) in cold thick ice clouds have been derived from satellite observations. Most NAP are detected in the Tropics (9 to 20% of clouds with T less than 202.5 K). Higher occurrences were found in the rare mid-latitudes very cold clouds. NAP occurrence increases as cloud temperature decreases and NAP are more numerous in January than July. Comparisons of NAP and lightning distributions show that lightning is the main source of the NOx, which forms NAP in cold clouds. Qualitative comparisons of NAP with upper tropospheric humidity distributions suggest that NAP play a role in the dehydration of the upper troposphere when the tropopause is colder than 195K.

  14. REACT-Mod: a mathematical model for transient calculation of chemical reactions with U-Pu-Np-Tc in the aqueous nitric acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Tachimori, Shoichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Kitamura, Tatsuaki

    1996-10-01

    A computer code REACT-Mod which simulates various chemical reactions in an aqueous nitric acid solution involving uranium, plutonium, neptunium, technetium etc. e.g., redox, radiolytic and disproportionation reactions of 68, was developed based on the kinetics model. The numerical solution method adopted in the code are two, a kinetics model totally based on the rate law of which differential equations are solved by the modified Porsing method, and a two-step model based on both the rate law and equilibrium law. Only the former treats 27 radiolytic reactions. The latter is beneficially used to have a quick and approximate result by economical computation. The present report aims not only to explain the concept, chemical reactions treated and characteristics of the model but also to provide details of the program for users of the REACT-Mod code. (author)

  15. Determination of plutonium in nitric acid solutions using energy dispersive L X-ray fluorescence with a low power X-ray generator

    Energy Technology Data Exchange (ETDEWEB)

    Py, J. [Laboratoire Chrono-Environnement, UMR CNRS 6249, Université de Franche-Comté, 16 route de Gray, F-25030 Besançon (France); Commissariat à l’Énergie Atomique, Centre de Valduc, F-21120 Is-sur-Tille (France); Groetz, J.-E., E-mail: jegroetz@univ-fcomte.fr [Laboratoire Chrono-Environnement, UMR CNRS 6249, Université de Franche-Comté, 16 route de Gray, F-25030 Besançon (France); Hubinois, J.-C.; Cardona, D. [Commissariat à l’Énergie Atomique, Centre de Valduc, F-21120 Is-sur-Tille (France)

    2015-04-21

    This work presents the development of an in-line energy dispersive L X-ray fluorescence spectrometer set-up, with a low power X-ray generator and a secondary target, for the determination of plutonium concentration in nitric acid solutions. The intensity of the L X-rays from the internal conversion and gamma rays emitted by the daughter nuclei from plutonium is minimized and corrected, in order to eliminate the interferences with the L X-ray fluorescence spectrum. The matrix effects are then corrected by the Compton peak method. A calibration plot for plutonium solutions within the range 0.1–20 g L{sup −1} is given.

  16. Synergistic extraction of U(VI) and Th(IV) from nitric acid media withHBMPPT and TBP in toluene

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The synergistic extraction of U(VI) and Th(IV) from nitric acid solutionby HBMPPT (4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione) andTBP (tributylphosphate ) in toluene was studied. The extraction abilityof HBMPPT for U(VI) and Th(IV) was not so high, but when a little TBP was added in, theability to extract U(VI) and Th(IV) was improved. The extracted complexes may be presented as UO2NO3.BMPPT.TBP and UO2(BMPPT)2 .TBP for U(VI), and Th(NO3)3.BMPPT.TBP andTh(NO3)2 (BMPPT)2.TBP for Th(IV),respectively, in the synergisticextraction system. The synergistic effect of HBMPPT and TBP makes the separationcoefficient of U(VI) /Th(IV) or U(VI)/Eu(III) reach a high value.

  17. The use of Liquid Smoke as A Substitute for Nitric Acid for Extraction of Amorphous silica from Rice husk through Sol-Gel Route

    Directory of Open Access Journals (Sweden)

    Wasinton Simanjuntak

    2016-08-01

    Full Text Available This study assessed the potential of liquid smoke as substitute for nitric acid for production of rice husk silica using sol-gel method. The efficacy of liquid smoke was compared to that of 10% HNO3 solution in terms of the volume required and the mass of silica obtained. Further evaluation was made by comparing the characteristics of the silica as revealed by several characterization techniques include Fourier infrared spectroscopy, x-ray diffraction, scanning electron microscopy, and particle size analysis. No significant difference between the volume of the liquid smoke and the HNO3 solution required, as well as between the mass of silica obtained. Both samples display practically similar functionality and structure. The most interesting finding is that the silica obtained using liquid smoke exhibits more homogeneous surface morphology and narrower particle size distribution. Considering its environmentally friendly nature, it was concluded that liquid smoke is more advantageous than HNO3 solution.

  18. Structure of the oxide film on Ti–6Ta alloy after immersion test in 8 mol/L boiling nitric acid medium

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Dizi, E-mail: diziguo@126.com; Yang, Yingli; Wu, Jinping; Zhao, Bin; Zhao, Hengzhang; Su, Hangbiao; Lu, Yafeng

    2013-08-15

    Highlights: •Structure of the oxide film on Ti–6Ta alloy is studied by depth profile XPS. •TiO{sub 2} and Ta{sub 2}O{sub 5} are found in the top layer of the oxide film. •High valence oxide evolutes form Ti{sub 2}O{sub 3} and TaO. •Shielding effect of Ta{sub 2}O{sub 5} leads to the enhanced corrosion resistance of Ti–Ta alloy. -- Abstract: By using X-ray photoelectron spectroscopy (XPS), X-ray diffractometer (XRD) and scanning electron microscopy (SEM), we investigate the corrosion behavior and the structure of the oxide film of Ti–6Ta alloy that is subjected to the immersion corrosion test in 8 mol/L boiling nitric acid for 432 h. Based on the phase constitution indentified by depth profile XPS, the oxide film could be divided into three sub-layers along its thickness direction: the chemical stable TiO{sub 2} and Ta{sub 2}O{sub 5} are present in layer I; the sub-oxide Ti{sub 2}O{sub 3} and TaO are present in the layer II and layer III, and the high valence oxide evolutes from their sub-oxide gradually. Owing to the shielding effect of Ta{sub 2}O{sub 5}, the corrosion rate of the Ti–6Ta alloy decreases from 0.051 mm/y to 0.014 mm/y with increasing immersion time, showing an excellent corrosion resistance in 8 mol/L boiling nitric acid.

  19. Microstructures of Al7.5Cr22.5Fe35Mn20Ni15 High-Entropy Alloy and Its Polarization Behaviors in Sulfuric Acid, Nitric Acid and Hydrochloric Acid Solutions

    Directory of Open Access Journals (Sweden)

    Chun-Huei Tsau

    2016-08-01

    Full Text Available This paper investigates the microstructures and the polarization behaviors of Al7.5Cr22.5Fe35Mn20Ni15 high-entropy alloy in 1M (1 mol/L deaerated sulfuric acid (H2SO4, nitric acid (HNO3, and hydrochloric acid (HCl solutions at temperatures of 30–60 °C. The three phases of the Al7.5Cr22.5Fe35Mn20Ni15 high-entropy alloy are body-centered cubic (BCC dendrites, face-centered cubic (FCC interdendrites, and ordered BCC precipitates uniformly dispersed in the BCC dendrites. The different phases were corroded in different acidic solutions. The passivation regions of the Al7.5Cr22.5Fe35Mn20Ni15 alloy are divided into three and two sub-regions in the solutions of H2SO4 and HNO3 at 30–60 °C, respectively. The passivation region of the Al7.5Cr22.5Fe35Mn20Ni15 alloy is also divided into two sub-domains in 1M deaerated HCl solution at 30 °C. The Al7.5Cr22.5Fe35Mn20Ni15 alloy has almost equal corrosion resistance in comparison with 304 stainless steel (304SS in both the 1M H2SO4 and 1M HCl solutions. The polarization behaviors indicated that the Al7.5Cr22.5Fe35Mn20Ni15 alloy possessed much better corrosion resistance than 304SS in 1M HNO3 solution. However, in 1M NaCl solution, the corrosion resistance of the Al7.5Cr22.5Fe35Mn20Ni15 alloy was less than 304SS.

  20. Chlorogenic acid protection of neuronal nitric oxide synthase-positive neurons in the hippocampus of mice with impaired learning and memory

    Institute of Scientific and Technical Information of China (English)

    Qiuyun Tu; Xiangqi Tang; Zhiping Hu

    2008-01-01

    BACKGROUND: Clinical practice and modern pharmacology have confirmed that ehlorogenic acid can ameliorate learning and memory impairments. OBJECTIVE: To observe the effects of chlorogenic acid on neuronal nitric oxide synthase (nNOS)-positive neurons in the mouse hippocampus, and to investigate the mechanisms underlying the beneficial effects of chlorogenic acid on learning and memory. DESIGN, TIME AND SETTING: The present randomized, controlled, neural cell morphological observation was performed at the Institute of Neurobiology, Central South University between January and May 2005.MATERIALS: Forty-eight female, healthy, adult, Kunming mice were included in this study. Learning and memory impairment was induced with an injection of 0.5 μL kainic acid (0.4 mg/mL) into the hippocampus.METHODS: The mice were randomized into three groups (n = 16): model, control, and chlorogenic acid-treated. At 2 days following learning and memory impairment induction, intragastric administration of physiological saline or chlorogenic acid was performed in the model and chlorogenic acid-treated groups, respectively. The control mice were administered 0.5 μ L physiological saline into the hippocampus, and 2 days later, they received an intragastric administration of physiological saline. Each mouse received two intragastric administrations (1 mL solution once) per day, for a total of 35 days. MAIN OUTCOME MEASURES: Detection of changes in hippocampal and cerebral cortical nNOS neurons by immunohistochemistry; determination of spatial learning and memory utilizing the Y-maze device.RESULTS: At day 7 and 35 after intervention, there was no significant difference in the number of nNOS-positive neurons in the cerebral cortex between the model, chlorogenic acid, and control groups (P > 0.05). Compared with the control group, the number of nNOS-positive neurons in the hippocampal CA1-4 region was significantly less in the model group (P 0.05). At day 7 following intervention, the number

  1. Polyphenol fraction of extra virgin olive oil protects against endothelial dysfunction induced by high glucose and free fatty acids through modulation of nitric oxide and endothelin-1

    Directory of Open Access Journals (Sweden)

    Carolina Emilia Storniolo

    2014-01-01

    Full Text Available Epidemiological and clinical studies have reported that olive oil reduces the incidence of cardiovascular disease. However, the mechanisms involved in this beneficial effect have not been delineated. The endothelium plays an important role in blood pressure regulation through the release of potent vasodilator and vasoconstrictor agents such as nitric oxide (NO and endothelin-1 (ET-1, respectively, events that are disrupted in type 2 diabetes. Extra virgin olive oil contains polyphenols, compounds that exert a biological action on endothelial function. This study analyzes the effects of olive oil polyphenols on endothelial dysfunction using an in vitro model that simulates the conditions of type 2 diabetes. Our findings show that high glucose and linoleic and oleic acids decrease endothelial NO synthase phosphorylation, and consequently intracellular NO levels, and increase ET-1 synthesis by ECV304 cells. These effects may be related to the stimulation of reactive oxygen species production in these experimental conditions. Hydroxytyrosol and the polyphenol extract from extra virgin olive oil partially reversed the above events. Moreover, we observed that high glucose and free fatty acids reduced NO and increased ET-1 levels induced by acetylcholine through the modulation of intracellular calcium concentrations and endothelial NO synthase phosphorylation, events also reverted by hydroxytyrosol and polyphenol extract. Thus, our results suggest a protective effect of olive oil polyphenols on endothelial dysfunction induced by hyperglycemia and free fatty acids.

  2. The Roles of Reactive Oxygen Species and Nitric Oxide in Perfluorooctanoic Acid-Induced Developmental Cardiotoxicity and l-Carnitine Mediated Protection

    Directory of Open Access Journals (Sweden)

    Meng Zhao

    2017-06-01

    Full Text Available Perfluorooctanoic acid (PFOA is an environmental contaminant that could induce developmental cardiotoxicity in a chicken embryo, which may be alleviated by l-carnitine. To explore the roles of reactive oxygen species (ROS and nitric oxide (NO in such changes and the potential effects of l-carnitine, fertile chicken eggs were exposed to PFOA via an air cell injection, with or without l-carnitine co-treatment. The ROS and NO levels in chicken embryo hearts were determined with electron spin resonance (ESR, and the protein levels of the nuclear factor κ-light chain-enhancer of activated B cells (NF-κB p65 and inducible nitric oxide synthase (iNOS in chicken embryo hearts were assessed with western blotting. The results of ESR indicated that PFOA exposure induced an elevation in the ROS levels in ED19 chicken embryo hearts and hatchling chicken hearts, while l-carnitine could alleviate such changes. Meanwhile, increased NO levels were observed in ED19 embryo hearts and hatchling hearts following PFOA exposure, while l-carnitine co-treatment exerted modulatory effects. Western blotting revealed that p65 translocation in ED19 embryo hearts and hatchling hearts was enhanced by PFOA, while l-carnitine co-treatment alleviated such changes. iNOS expression levels in ED19 embryo hearts followed the same pattern as NO levels, while a suppression of expression was observed in hatchling hearts exposed to PFOA. ROS/NF-κB p65 and iNOS/NO seem to be involved in the late stage (ED19 and post hatch of PFOA-induced developmental cardiotoxicity in a chicken embryo. l-carnitine could exert anti-oxidant and NO modulatory effects in the developing chicken embryo hearts, which likely contribute to its cardioprotective effects.

  3. The Roles of Reactive Oxygen Species and Nitric Oxide in Perfluorooctanoic Acid-Induced Developmental Cardiotoxicity and l-Carnitine Mediated Protection.

    Science.gov (United States)

    Zhao, Meng; Jiang, Qixiao; Wang, Wencheng; Geng, Min; Wang, Meng; Han, Yantao; Wang, Chunbo

    2017-06-08

    Perfluorooctanoic acid (PFOA) is an environmental contaminant that could induce developmental cardiotoxicity in a chicken embryo, which may be alleviated by l-carnitine. To explore the roles of reactive oxygen species (ROS) and nitric oxide (NO) in such changes and the potential effects of l-carnitine, fertile chicken eggs were exposed to PFOA via an air cell injection, with or without l-carnitine co-treatment. The ROS and NO levels in chicken embryo hearts were determined with electron spin resonance (ESR), and the protein levels of the nuclear factor κ-light chain-enhancer of activated B cells (NF-κB) p65 and inducible nitric oxide synthase (iNOS) in chicken embryo hearts were assessed with western blotting. The results of ESR indicated that PFOA exposure induced an elevation in the ROS levels in ED19 chicken embryo hearts and hatchling chicken hearts, while l-carnitine could alleviate such changes. Meanwhile, increased NO levels were observed in ED19 embryo hearts and hatchling hearts following PFOA exposure, while l-carnitine co-treatment exerted modulatory effects. Western blotting revealed that p65 translocation in ED19 embryo hearts and hatchling hearts was enhanced by PFOA, while l-carnitine co-treatment alleviated such changes. iNOS expression levels in ED19 embryo hearts followed the same pattern as NO levels, while a suppression of expression was observed in hatchling hearts exposed to PFOA. ROS/NF-κB p65 and iNOS/NO seem to be involved in the late stage (ED19 and post hatch) of PFOA-induced developmental cardiotoxicity in a chicken embryo. l-carnitine could exert anti-oxidant and NO modulatory effects in the developing chicken embryo hearts, which likely contribute to its cardioprotective effects.

  4. Reactions Involved in Fingerprint Development Using the Cyanoacrylate - Fuming Method

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, L.A.

    2001-07-30

    The Learning Objective is to present the basic chemistry research findings to the forensic community regarding development of latent fingerprints using the cyanoacrylate fuming method. Chemical processes involved in the development of latent fingerprints using the cyanoacrylate fuming method have been studied, and will be presented. Two major types of latent prints have been investigated--clean (eccrine) and oily (sebaceous) prints. Scanning electron microscopy (SEM) was used as a tool for determining the morphology of the polymer developed separately on clean and oily prints after cyanoacrylate fuming. A correlation between the chemical composition of an aged latent fingerprint, prior to development, and the quality of a developed fingerprint was observed in the morphology. The moisture in the print prior to fuming was found to be a critical factor for the development of a useful latent print. In addition, the amount of time required to develop a high quality latent print was found to be minimal. The cyanoacrylate polymerization process is extremely rapid. When heat is used to accelerate the fuming process, typically a period of 2 minutes is required to develop the print. The optimum development time is dependent upon the concentration of cyanoacrylate vapors within the enclosure.

  5. PREPARATION AND PROPERTIES OF FUMED SILICA/CYANATE ESTER NANOCOMPOSITES

    Institute of Scientific and Technical Information of China (English)

    Elhussein A.Taha; Jun-tao Wu; Kai Gao; Lin Guo

    2012-01-01

    Fumed silica/bisphenol A dicyanate ester (BADCy) nanocomposites were prepared by introducing different contents of nano-sized fumed SiO2 into the BADCy matrix.Two different average primary particle diameters of 12 and 40 nm were chosen.Dibutyltindilaurate (DBTDL) catalyst was chosen to catalyze the cyanate ester group into triazine group via cyclotrimerization reaction.The SEM micrographs indicated that the fumed SiO2 particles were homogeneously dispersed in the poly(bisphenol A dicyanate) matrix by means of ultrasonic treatment and the addition of a coupling agent.The FTIR spectroscopy shows that,not only DBTDL catalyzes the polymerization reaction but also-OH groups of the SiO2 particles surface help the catalyst for the complete polymerization of BADCy monomer.The thermal stability of the cured BADCy can be improved by adequate addition of fumed SiO2.A slight increase in the dielectric constant and dielectric loss values were identified by testing the dielectric properties of the prepared nanocomposite samples.By increasing the SiO2 content,there was a slight increasing in the thermal conductivity values of the tested samples.The obtained results proved that the fumed silica/BADCy nanocomposites had good thermal and dielectrical properties and can be used in many applications such as in the thermal insulation field.

  6. Vapor pressures and calculated heats of vaporization of concentrated nitric acid solutions in the composition range 71 to 89 percent nitrogen dioxide, 1 to 10 percent water, and in the temperature range 10 to 60 degrees C

    Science.gov (United States)

    Mckeown, A B; Belles, Frank E

    1954-01-01

    Total vapor pressures were measured for 16 acid mixtures of the ternary system nitric acid, nitrogen dioxide, and water within the temperature range 10 degrees to 60 degrees Celsius, and with the composition range 71 to 89 weight percent nitric acid, 7 to 20 weight percent nitrogen dioxide, and 1 to 10 weight percent water. Heats of vaporization were calculated from the vapor pressure measurements for each sample for the temperatures 25, 40, and 60 degrees Celsius. The ullage of the apparatus used for the measurements was 0.46. Ternary diagrams showing isobars as a function of composition of the system were constructed from experimental and interpolated data for the temperatures 25, 40, 45, and 60 degrees C and are presented herein.

  7. A trans-Hyponitrite Intermediate in the Reductive Coupling and Deoxygenation of Nitric Oxide by a Tricopper-Lewis Acid Complex.

    Science.gov (United States)

    Lionetti, Davide; de Ruiter, Graham; Agapie, Theodor

    2016-04-20

    The reduction of nitric oxide (NO) to nitrous oxide (N2O) is a process relevant to biological chemistry as well as to the abatement of certain environmental pollutants. One of the proposed key intermediates in NO reduction is hyponitrite (N2O2(2-)), the product of reductive coupling of two NO molecules. We report the reductive coupling of NO by an yttrium-tricopper complex generating a trans-hyponitrite moiety supported by two μ-O-bimetallic (Y,Cu) cores, a previously unreported coordination mode. Reaction of the hyponitrite species with Brønsted acids leads to the generation of N2O, demonstrating the viability of the hyponitrite complex as an intermediate in NO reduction to N2O. The additional reducing equivalents stored in each tricopper unit are employed in a subsequent step for N2O reduction to N2, for an overall (partial) conversion of NO to N2. The combination of Lewis acid and multiple redox active metals facilitates this four electron conversion via an isolable hyponitrite intermediate.

  8. Gibberellic acid nitrite stimulates germination of two species of light-requiring seeds via the nitric oxide pathway.

    Science.gov (United States)

    Jovanović, Vladan; Giba, Zlatko; Djoković, Dejan; Milosavljević, Slobodan; Grubisić, Dragoljub; Konjević, Radomir

    2005-06-01

    We used two species of light-requiring seeds, Paulownia tomentosa, which have absolute light requirement (no germination in darkness), and Stellaria media seeds, which germinate in darkness to a certain extent because of presence of preformed active phytochrome, to obtain results strongly suggesting that gibberellic acid nitrite stimulates seed germination via its capability as a functional NO donor. Exogenous application of gibberellic acid nitrite stimulates gibberellin-insensitive Stellaria media seed germination in darkness as do a wide variety of NO donors. Pure gibberellic acid could replace the light requirement of P. tomentosa seeds, thus enabling them to germinate in darkness. Gibberellic acid nitrite did not have this effect. A stimulative effect from gibberellic acid nitrite could be detected only after exposure of these seeds to short, 10 min, pulse of red light. Taken together, these results suggest that gibberellic activity of gibberellic acid nitrite is lost after nitrosation but, regarding to the presence of -O-NO moiety in the molecule, gibberellic acid nitrite shares stimulative properties in seed germination with other compounds with NO-releasing properties.

  9. Catalytic Disposal of Cooking Fume Discharged from the Restaurant

    Institute of Scientific and Technical Information of China (English)

    WANG; XiangYu

    2001-01-01

    The cooking oil fume pollution have been becoming a serious problem.1 Though several methods on disposal technology of the fume have been developed at home and abroad, such as filtration process, electrostatic process and wet process, practical and effective technology is still needed.2In the present study, we will report a new disposal process of cooking fume, which were turned complete into water and CO2 in the presence of the catalysts.  Catalysts were prepared by the following procedure. First, layer of A12O3 was painted on the inner pore surface of ceramic honeycomb carrier. Second, a solution of platinum and palladium salts in alcohol was used for impregnation in a suitable concentration to obtain a catalyst 0.3% noble metals.  ……

  10. Absorption Behavior of Anion Exchange Resin to Minimal Plutonium in 3 to 4 mol/L Nitric Acid Medium

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>The acidity of liquor in the process of plutonium purification using extraction method is 3 to 4 mol/L and liquor contains minimal plutonium of certain concentration, the reclamation of plutonium is usually

  11. Double shroud delivery of silica precursor for reducing hexavalent chromium in welding fume.

    Science.gov (United States)

    Wang, Jun; Kalivoda, Mark; Guan, Jianying; Theodore, Alexandros; Sharby, Jessica; Wu, Chang-Yu; Paulson, Kathleen; Es-Said, Omar

    2012-01-01

    The welding process yields a high concentration of nanoparticles loaded with hexavalent chromium (Cr(6+)), a known human carcinogen. Previous studies have demonstrated that using tetramethylsilane (TMS) as a shielding gas additive can significantly reduce the Cr(6+) concentration in welding fume particles. In this study, a novel insulated double shroud torch (IDST) was developed to further improve the reduction of airborne Cr(6+) concentration by separating the flows of the primary shielding gas and the TMS carrier gas. Welding fumes were collected from a welding chamber in the laboratory and from a fixed location near the welding arc in a welding facility. The Cr(6+) content was analyzed with ion chromatography and X-ray photoelectron spectroscopy (XPS). Results from the chamber sampling demonstrated that the addition of 3.2 ≈ 5.1% of TMS carrier gas to the primary shielding gas resulted in more than a 90% reduction of airborne Cr(6+) under all shielding gas flow rates. The XPS result confirmed complete elimination of Cr(6+) inside the amorphous silica shell. Adding 100 ≈ 1000 ppm of nitric oxide or carbon monoxide to the shielding gas could also reduce Cr(6+) concentrations up to 57% and 35%, respectively; however, these reducing agents created potential hazards from the release of unreacted agents. Results of the field test showed that the addition of 1.6% of TMS carrier gas to the primary shielding gas reduced Cr(6+) concentration to the limitation of detection (1.1 μg/m(3)). In a worst-case scenario, if TMS vapor leaked into the environment without decomposition and ventilation, the estimated TMS concentration in the condition of field sampling would be a maximum 5.7 ppm, still well below its flammability limit (1%). Based on a previously developed cost model, the use of TMS increases the general cost by 3.8%. No visual deterioration of weld quality caused by TMS was found, although further mechanical testing is necessary.

  12. 42 CFR 84.1140 - Dust, fume, and mist respirators; performance requirements; general.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Dust, fume, and mist respirators; performance... Respirators and Combination Gas Masks § 84.1140 Dust, fume, and mist respirators; performance requirements; general. Dust, fume, and mist respirators and the individual components of each such device shall,...

  13. 42 CFR 84.1149 - Airflow resistance tests; all dust, fume, and mist respirators; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Airflow resistance tests; all dust, fume, and mist... RESPIRATORY PROTECTIVE DEVICES Dust, Fume, and Mist; Pesticide; Paint Spray; Powered Air-Purifying High Efficiency Respirators and Combination Gas Masks § 84.1149 Airflow resistance tests; all dust, fume, and...

  14. Fatty acid transduction of nitric oxide signaling: multiple nitrated unsaturated fatty acid derivatives exist in human blood and urine and serve as endogenous peroxisome proliferator-activated receptor ligands.

    Science.gov (United States)

    Baker, Paul R S; Lin, Yiming; Schopfer, Francisco J; Woodcock, Steven R; Groeger, Alison L; Batthyany, Carlos; Sweeney, Scott; Long, Marshall H; Iles, Karen E; Baker, Laura M S; Branchaud, Bruce P; Chen, Yuqing E; Freeman, Bruce A

    2005-12-23

    Mass spectrometric analysis of human plasma and urine revealed abundant nitrated derivatives of all principal unsaturated fatty acids. Nitrated palmitoleic, oleic, linoleic, linolenic, arachidonic and eicosapentaenoic acids were detected in concert with their nitrohydroxy derivatives. Two nitroalkene derivatives of the most prevalent fatty acid, oleic acid, were synthesized (9- and 10-nitro-9-cis-octadecenoic acid; OA-NO2), structurally characterized and determined to be identical to OA-NO2 found in plasma, red cells, and urine of healthy humans. These regioisomers of OA-NO2 were quantified in clinical samples using 13C isotope dilution. Plasma free and esterified OA-NO2 concentrations were 619 +/- 52 and 302 +/- 369 nm, respectively, and packed red blood cell free and esterified OA-NO2 was 59 +/- 11 and 155 +/- 65 nm. The OA-NO2 concentration of blood is approximately 50% greater than that of nitrated linoleic acid, with the combined free and esterified blood levels of these two fatty acid derivatives exceeding 1 microm. OA-NO2 is a potent ligand for peroxisome proliferator activated receptors at physiological concentrations. CV-1 cells co-transfected with the luciferase gene under peroxisome proliferator-activated receptor (PPAR) response element regulation, in concert with PPARgamma, PPARalpha, or PPARdelta expression plasmids, showed dose-dependent activation of all PPARs by OA-NO2. PPARgamma showed the greatest response, with significant activation at 100 nm, while PPARalpha and PPARdelta were activated at approximately 300 nm OA-NO2. OA-NO2 also induced PPAR gamma-dependent adipogenesis and deoxyglucose uptake in 3T3-L1 preadipocytes at a potency exceeding nitrolinoleic acid and rivaling synthetic thiazo-lidinediones. These data reveal that nitrated fatty acids comprise a class of nitric oxide-derived, receptor-dependent, cell signaling mediators that act within physiological concentration ranges.

  15. 我国硝酸、硝酸铵行业现状及发展趋势——在2011年硝酸硝铵行业工作会上的讲话%Present Status of Nitric Acid and Ammonium Nitrate Industry in China and Development Trend——A Speech at Working Conference on Nitric Acid and Ammonium Nitrate Industry in 2011

    Institute of Scientific and Technical Information of China (English)

    靳小桂

    2011-01-01

    我国硝酸生产以双加压法工艺为主.2010年,我国硝酸产能9 600 kt,产量7 923 kt(实物量),浓硝酸产量2 356 kt;硝酸铵产能6000 kt,产量4 200 kt.硝酸主要下游产品在今后几年内将保持稳定增长,预计未来5年对硝酸的需求年均增长率为7.7%,至2015年用于工业生产的硝酸量将达3 600 kt;随着我国民爆行业产品升级、化肥复合化率提高、硝基复合肥所占比重增大,对硝酸铵的需求也将有较大增长,至2015年磷酸铵产能将达到10 000 kt/a,需硝酸7 900 kt/a.预计3年内我国硝酸产能将达15 000 kt/a,在淘汰落后产能的条件下,仍将有2 000 kt/a产能富余,为此提出了促进硝酸、硝酸铵行业健康发展的建议.%The production of nitric acid in China is mainly based on the dual pressure process. In 2010 the capacity of nitric acid in China was 9 600 kt, the output 7 923 kt (product), and the output of concentrated nitric acid 2 356 kt. The capacity of ammonium nitrate was 6 000 kt, and its output 4 200 kt. The chief downstream products of nitric acid will continue to grow steadily in the next few years, and it is expected that in the next 5 years the demand for nitric acid will increase by 7. 7% a year on the average. By 2015 nitric acid for industrial production will reach 3 600 kt. With the upgrading of the products from the industry for explosives for civil use, increase in the output of compound fertilizers, and rise in the proportion of nitro compound fertilizers, the demand for ammonium nitrate will grow by a large margin. By 2015 the capacity of ammonium nitrate will attain 10 000 kt/a, requiring 7 900 kt/a of nitric acid. In three years the capacity of nitric acid in China will be 15 000 kt/a. Under the conditions of elimination of backward capacity, there is still a surplus of 2 000 kt/a, so suggestions are proposed for the promotion of the sound development of the nitric acid and ammonium nitrate industry.

  16. deFUME: Dynamic exploration of functional metagenomic sequencing data

    DEFF Research Database (Denmark)

    van der Helm, Eric; Geertz-Hansen, Henrik Marcus; Genee, Hans Jasper

    2015-01-01

    Functional metagenomic selections represent a powerful technique that is widely applied for identification of novel genes from complex metagenomic sources. However, whereas hundreds to thousands of clones can be easily generated and sequenced over a few days of experiments, analyzing the data...... to a comprehensive visual data overview that facilitates effortless inspection of gene function, clustering and distribution. The webserver is available at cbs.dtu.dk/services/deFUME/and the source code is distributed at github.com/EvdH0/deFUME....

  17. Returning perchlorate-contaminated fume hood systems to service. Part II. Disassembly, decontamination, disposal, and analytical procedures.

    Science.gov (United States)

    Bader, M; Phillips, C C; Mueller, T R; Underwood, W S; Whitson, S D

    1999-06-01

    Part I presented work leading up to and including a pilot study for remediation of laboratory fume hood systems contaminated with residues from processes that used fuming perchloric acid. Since publication of Part I, three incidents involving explosions and fires related to perchlorates have come to the attention of the authors. Experience has been gained through decontamination/remediation of 41 additional systems. This article expands on previous one and includes (1) administrative details that need to be addressed before and during the execution of the decontamination itself, (2) a seven-step procedure for decontamination-remediation/disposal, (3) some precautions associated with the use of methylene blue as a diagnostic tool for perchlorates, and-specific electrode to augment or replace the methylene blue test.

  18. Study of the nitric acid influence on the production of Ce O{sub 2} with high specific surface area; Estudo da influencia do acido nitrico na obtencao de CeO{sub 2} com alta area superficial especifica

    Energy Technology Data Exchange (ETDEWEB)

    Albanez, Nelma Kunrath; Bressiani, Jose Carlos [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)

    1996-12-31

    The cerium oxide (Ce O{sub 2}) main characteristics for use as catalyst in an exhaust gases purification system are: high specific surface area (approximately 30 m{sup 2}/g after calcination at 800 deg C/ 2 hs), and thermal stability. The Ce O{sub 2} powders obtained by conventional route, i.e., precipitation, and submitted high temperature (800 deg C) heat treatments, showed low specific surface area. In this work nitric acid effects on the Ce O{sub 2} surface area values were investigated. The variables studied were nitric acid concentration, humidity content in the raw material, re pulp after leaching, addition of hydrogen peroxide (H{sub 2} O{sub 2}) and starting material specific surface area. By this process, it was possible to obtain powders with specific surface area larger than 40 m{sup 2}/g, after treatment at 800 deg C during two hours. (author) 8 refs., 3 figs., 1 tab.

  19. Reevaluation of JACS code system benchmark analyses of the heterogeneous system. Fuel rods in U+Pu nitric acid solution system

    Energy Technology Data Exchange (ETDEWEB)

    Takada, Tomoyuki; Miyoshi, Yoshinori; Katakura, Jun-ichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2003-03-01

    In order to perform accuracy evaluation of the critical calculation by the combination of multi-group constant library MGCL and 3-dimensional Monte Carlo code KENO-IV among critical safety evaluation code system JACS, benchmark calculation was carried out from 1980 in 1982. Some cases where the neutron multiplication factor calculated in the heterogeneous system in it was less than 0.95 were seen. In this report, it re-calculated by considering the cause about the heterogeneous system of the U+Pu nitric acid solution systems containing the neutron poison shown in JAERI-M 9859. The present study has shown that the k{sub eff} value less than 0.95 given in JAERI-M 9859 is caused by the fact that the water reflector below a cylindrical container was not taken into consideration in the KENO-IV calculation model. By taking into the water reflector, the KENO-IV calculation gives a k{sub eff} value greater than 0.95 and a good agreement with the experiment. (author)

  20. Unravelling the potential of nitric acid as a surface modifier for improving the hemocompatibility of metallocene polyethylene for blood contacting devices

    Science.gov (United States)

    Vellayappan, Muthu Vignesh; Muhamad, Ida Idayu

    2016-01-01

    Design of blood compatible surfaces is obligatory to minimize platelet surface interactions and improve the thromboresistance of foreign surfaces when they are utilized as biomaterials particularly for blood contacting devices. Pure metallocene polyethylene (mPE) and nitric acid (HNO3) treated mPE antithrombogenicity and hydrophilicity were investigated. The contact angle of the mPE treated with HNO3 decreased. Surface of mPE and HNO3 treated mPE investigated with FTIR revealed no major changes in its functional groups. 3D Hirox digital microscopy, SEM and AFM images show increased porosity and surface roughness. Blood coagulation assays prothrombin time (PT) and activated partial thromboplastin time (APTT) were delayed significantly (P hemocompatibility of HNO3 treated mPE. To determine that HNO3 does not deteriorate elastic modulus of mPE, the elastic modulus of mPE and HNO3 treated mPE was compared and the result shows no significant difference. Hence, the overall observation suggests that the novel HNO3 treated mPE may hold great promises to be exploited for blood contacting devices like grafts, catheters, and etc. PMID:26819837

  1. Nitric acid activation of graphite granules to increase the performance of the non-catalyzed oxygen reduction reaction (ORR) for MFC applications

    Energy Technology Data Exchange (ETDEWEB)

    Erable, Benjamin [School of Chemical Engineering and Advanced Materials, Newcastle University, Newcastle upon Tyne - NE1 7RU (United Kingdom); Laboratoire de Genie Chimique, CNRS-Universite de Toulouse, 5 rue Paulin Talabot, BP1301, 31106 Toulouse (France); Duteanu, Narcis [School of Chemical Engineering and Advanced Materials, Newcastle University, Newcastle upon Tyne - NE1 7RU (United Kingdom); Faculty of Industrial Chemistry and Environmental Engineering, University ' ' POLITEHNICA' ' Timisoara, 300006 Timisoara (Romania); Kumar, S.M. Senthil; Scott, Keith [School of Chemical Engineering and Advanced Materials, Newcastle University, Newcastle upon Tyne - NE1 7RU (United Kingdom); Feng, Yujie [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No. 202, Haihe Road, Harbin 150090 (China); Ghangrekar, Makarand M. [School of Chemical Engineering and Advanced Materials, Newcastle University, Newcastle upon Tyne - NE1 7RU (United Kingdom); Department of Civil Engineering, Indian Institute of Technology, Kharagpur - 721302 (India)

    2009-07-15

    Nitric acid and thermal activation of graphite granules were explored to increase the electrocatalytic performance of dissolved oxygen reduction at neutral pH for microbial fuel cell (MFC) applications. Electrochemical experiments showed an improvement of +400 mV in open circuit potential for graphite granules when they were activated. The improvement of ORR performance observed with activated granules was correlated to the increase of Brunauer-Emmett-Teller (BET) surface of the activated material and the emergence of nitrogen superficial groups revealed by X-ray photoelectron spectroscopy (XPS) analysis on its surface. The use of activated graphite granules in the cathodic compartment of a dual-chamber MFC led to a high open circuit voltage of 1050 mV, which is among one of the highest reported so far. The stable performance of this cathode material (current density of 96 A m{sup -3} at +200 mV/Ag-AgCl) over a period of 10 days demonstrated its applicability as a cathode material without any costly noble metal. (author)

  2. The effect of heating temperature and nitric acid treatments on the performance of Cu- and Zn-based broad spectrum respirator carbons.

    Science.gov (United States)

    Smith, J W H; Romero, J V; Dahn, T R; Dunphy, K; Sullivan, B; Mallay, M; Croll, L M; Reynolds, J H; Andress, C; Dahn, J R

    2011-12-01

    Impregnated activated carbons (IACs) that are used in broad spectrum gas mask applications have historically contained copper and/or zinc impregnants. The addition of an oxidizing agent, such as nitric acid (HNO(3)) can be useful in distributing the metallic impregnants uniformly on the activated carbon substrate. In this work, we study IACs prepared from copper nitrate (Cu(NO(3))(2)) and zinc nitrate (Zn(NO(3))(2)) precursors as a function of HNO(3) content present in the impregnating solution and as a function of heating temperature. The gas adsorption capacity of the IACs was determined by dynamic flow testing using sulfur dioxide (SO(2)), ammonia (NH(3)), hydrogen cyanide (HCN) and cyclohexane (C(6)H(12)) challenge gases under dry and humid conditions. The thermal decomposition and distribution of the impregnant on the activated carbon substrate is studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermal analysis techniques. Relationships between gas adsorption capacity, impregnant distribution and the species of surface impregnants are discussed.

  3. Solubility of PdI/sub 2/ in nitrate and perchlorate solutions. [For use in spent fuels processing; solvents are water, nitric acid, calcium nitrate, and sodium perchlorate

    Energy Technology Data Exchange (ETDEWEB)

    Horner, D.E.; Mailen, J.C.; Bigelow, H.R.

    1976-01-01

    This paper reports the solubilities of PdI/sub 2/ as measured in nitric acid by a tracer technique and in water, calcium nitrate, and sodium perchlorate solutions by a specific ion electrode technique. The tracer technique measures all the soluble iodine species, whereas the specific ion electrode measures only simple iodide ions (I/sup -/). When compared on the basis of ionic strength, the values obtained in the nitrate solutions by the two methods were in reasonable agreement. The solubilities in perchlorate solution were much higher than in nitrate, possibly because of ionic equilibria involving Pd/sup 4 +/, but this was not resolved in this work. The activity product constant, K/sub ap(PdI/sub 2/)/ = (2.5 +- 0.4) x 10/sup -23/ (25/sup 0/C), was calculated from PdI/sub 2/ solubility in water. With this value and the standard electrode potentials from the literature, the free energy of formation for PdI/sub 2/ was calculated to be --13.6 kcal/mol.

  4. Nitric oxide suppresses the inhibitory effect of abscisic acid on seed germination by S-nitrosylation of SnRK2 proteins.

    Science.gov (United States)

    Wang, Pengcheng; Zhu, Jian-Kang; Lang, Zhaobo

    2015-01-01

    Nitric oxide (NO) plays important roles in plant development, and biotic and abiotic stress responses. In a recent study, we showed that endogenous NO negatively regulates abscisic acid (ABA) signaling in guard cells by inhibiting sucrose nonfermenting 1 (SNF1)-related protein kinase 2.6 (SnRK2.6)/open stomata 1(OST1) through S-nitrosylation. Application of NO breaks seed dormancy and alleviates the inhibitory effect of ABA on seed germination and early seedling growth, but it is unclear how NO functions at the stages of seed germination and early seedling development. Here, we show that like SnRK2.6, SnRK2.2 can be inactivated by S-nitrosoglutathione (GSNO) treatment through S-nitrosylation. SnRK2.2 and the closely related SnRK2.3 are known to play redundant roles in ABA inhibition of seed germination in Arabidopsis. We found that treatment with the NO donor SNP phenocopies the snrk2.2snrk2.3 double mutant in conferring ABA insensitivity at the stages of seed germination and early seedling growth. Our results suggest that NO negatively regulates ABA signaling in germination and early seedling growth through S-nitrosylation of SnRK2.2 and SnRK2.3.

  5. Techno-Economic Feasibility Study of Renewable Power Systems for a Small-Scale Plasma-Assisted Nitric Acid Plant in Africa

    Directory of Open Access Journals (Sweden)

    Aikaterini Anastasopoulou

    2016-12-01

    Full Text Available The expected world population growth by 2050 is likely to pose great challenges in the global food demand and, in turn, in the fertilizer consumption. The Food and Agricultural Organization of the United Nations has forecasted that 46% of this projected growth will be attributed to Africa. This, in turn, raises further concerns about the sustainability of Africa’s contemporary fertilizer production, considering also its high dependence on fertilizer imports. Based on these facts, a novel “green” route for the synthesis of fertilizers has been considered in the context of the African agriculture by means of plasma technology. More precisely, a techno-economic feasibility study has been conducted for a small-scale plasma-assisted nitric acid plant located in Kenya and South Africa with respect to the electricity provision by renewable energy sources. In this study, standalone solar and wind power systems, as well as a hybrid system, have been assessed for two different electricity loads against certain economic criteria. The relevant simulations have been carried out in HOMER software and the optimized configurations of each examined renewable power system are presented in this study.

  6. Photosynthetic and antioxidant responses of Liquidambar formosana and Schima superba seedlings to sulfuric-rich and nitric-rich simulated acid rain.

    Science.gov (United States)

    Chen, Juan; Wang, Wen-Hua; Liu, Ting-Wu; Wu, Fei-Hua; Zheng, Hai-Lei

    2013-03-01

    To study whether differential responses occur in photosynthesis and antioxidant system for seedlings of Liquidambar formosana, an acid rain (AR)-sensitive tree species and Schima superba, an AR-tolerant tree species treated with three types of pH 3.0 simulated AR (SiAR) including sulfuric-rich (S-SiAR), nitric-rich (N-SiAR), sulfate and nitrate mixed (SN-SiAR), we investigated the changes of leaf necrosis, chlorophyll content, soluble protein and proline content, photosynthesis and chlorophyll fluorescence characteristics, reactive oxygen species production, membrane lipid peroxidation, small molecular antioxidant content, antioxidant enzyme activities and related protein expressions. Our results showed that SiAR significantly caused leaf necrosis, inhibited photosynthesis, induced superoxide radical and hydrogen peroxide generation, aggravated membrane lipid peroxidation, changed antioxidant enzyme activities, modified related protein expressions such as Cu/Zn superoxide dismutase (SOD), l-ascorbate peroxidase (APX, EC 1. 11. 1. 11), glutathione S transferase (GST, EC 2. 5. 1. 18) and Rubisco large subunit (RuBISCO LSU), altered non-protein thiols (NPT) and glutathione (GSH) content in leaves of L. formosana and S. superba. Taken together, we concluded that the damages caused by SiAR in L. formosana were more severe and suffered from more negative impacts than in S. superba. S-SiAR induced more serious damages for the plants than did SN-SiAR and N-SiAR.

  7. NITRIC OXIDE-ASSOCIATED PROTEIN1 (AtNOA1) is essential for salicylic acid-induced root waving in Arabidopsis thaliana.

    Science.gov (United States)

    Zhao, Xiang; Wang, Jin; Yuan, Jing; Wang, Xi-Li; Zhao, Qing-Ping; Kong, Pei-Tao; Zhang, Xiao

    2015-07-01

    Root waving responses have been attributed to both environmental and genetics factors, but the potential inducers and transducers of root waving remain elusive. Thus, the identification of novel signal elements related to root waving is an intriguing field of research. Genetic, physiological, cytological, live cell imaging, and pharmacological approaches provide strong evidence for the involvement of Arabidopsis thaliana NITRIC OXIDE-ASSOCIATED PROTEIN1 (AtNOA1) in salicylic acid (SA)-induced root waving. SA specially induced root waving, with an overall decrease in root elongation in A. thaliana, and this SA-induced response was disrupted in the Atnoa1 mutant, as well as in nonexpresser of pathogenesis-related genes 1 (npr1), which is defective in SA-mediated plant defense signal transduction, but not in npr3/4 single and double mutants. The expression assays revealed that the abundance of AtNOA1 was significantly increased by application of SA. Genetic and pharmacological analyses showed that SA-induced root waving involved an AtNOA1-dependent Ca(2+) signal transduction pathway, and PIN-FORMED2 (PIN2) -based polar auxin transport possibly plays a crucial role in this process. Our work suggests that SA signaling through NPR1 and AtNOA1 is involved in the control of root waving, which provides new insights into the mechanisms that control root growth behavior on a hard agar surface.

  8. A pulse radiolysis investigation of the reactions of tributyl phosphate with the radical products of aqueous nitric acid irradiation.

    Science.gov (United States)

    Mincher, Bruce J; Mezyk, Stephen P; Martin, Leigh R

    2008-07-17

    Tributyl phosphate (TBP) is the most common organic compound used in liquid-liquid separations for the recovery of uranium, neptunium, and plutonium from acidic nuclear fuel dissolutions. The goal of these processes is to extract the actinides while leaving fission products in the acidic, aqueous phase. However, the radiolytic degradation of TBP has been shown to reduce separation factors of the actinides from fission products and to impede the back-extraction of the actinides during stripping. As most previous investigations of the radiation chemistry of TBP have focused on steady state radiolysis and stable product identification, with dibutylphosphoric acid (HDBP) invariably being the major product, here we have determined room temperature rate constants for the reactions of TBP and HDBP with the hydroxyl radical [(5.00 +/- 0.05) x 10(9), (4.40 +/- 0.13) x 10(9) M(-1) s(-1)], hydrogen atom [(1.8 +/-0.2) x 10(8), (1.1 +/- 0.1) x 10(8) M(-1) s(-1)], nitrate radical [(4.3 +/- 0.7) x 10(6), (2.9 +/- 0.2) x 10(6) M(-1) s(-1)], and nitrite radical (<2 x 10 (5), <2 x 10(5) M(-1) s(-1)), respectively. These data are used to discuss the mechanism of TBP radical-induced degradation.

  9. A Study on Genotoxicity of Cooking Fume from Rapessed Oil

    Institute of Scientific and Technical Information of China (English)

    CHENHUA; YANGMINGDING; 等

    1992-01-01

    The present article reports the genotoxic potential of rapeseed oil cooking fume investigated by a battery of short-term tests(Ames test,SCE/V79 in vitor and mice micronucleus in vivo test).The results showed that the cooking fume contained mutagenic activity.In the presence of S9 mix,an increase in the number of the Salmonella TA98 was observed at doses ranging from 1.0 to 5.0mg/plate,and the SCE frequencies of V79 cell were markedly raised at doses ranging from 0.05 to 0.5mg·m-1.The positive result was also obtained in mice micronucleus assay,the mice had inhaled the cooking fume a week earlier.The requency of mice bone marrow MN-PCR ws increased and it showed a remarkable time-dose-response relationship during the 4 weeks exposure.The results suggested that this cooking fume exposure may be a risk factor of lung cancer in Chinese women.

  10. Exposure to inhalable, respirable, and ultrafine particles in welding fume.

    Science.gov (United States)

    Lehnert, Martin; Pesch, Beate; Lotz, Anne; Pelzer, Johannes; Kendzia, Benjamin; Gawrych, Katarzyna; Heinze, Evelyn; Van Gelder, Rainer; Punkenburg, Ewald; Weiss, Tobias; Mattenklott, Markus; Hahn, Jens-Uwe; Möhlmann, Carsten; Berges, Markus; Hartwig, Andrea; Brüning, Thomas

    2012-07-01

    This investigation aims to explore determinants of exposure to particle size-specific welding fume. Area sampling of ultrafine particles (UFP) was performed at 33 worksites in parallel with the collection of respirable particles. Personal sampling of respirable and inhalable particles was carried out in the breathing zone of 241 welders. Median mass concentrations were 2.48 mg m(-3) for inhalable and 1.29 mg m(-3) for respirable particles when excluding 26 users of powered air-purifying respirators (PAPRs). Mass concentrations were highest when flux-cored arc welding (FCAW) with gas was applied (median of inhalable particles: 11.6 mg m(-3)). Measurements of particles were frequently below the limit of detection (LOD), especially inside PAPRs or during tungsten inert gas welding (TIG). However, TIG generated a high number of small particles, including UFP. We imputed measurements welding fume. Concentrations were mainly predicted by the welding process and were significantly higher when local exhaust ventilation (LEV) was inefficient or when welding was performed in confined spaces. Substitution of high-emission techniques like FCAW, efficient LEV, and using PAPRs where applicable can reduce exposure to welding fume. However, harmonizing the different exposure metrics for UFP (as particle counts) and for the respirable or inhalable fraction of the welding fume (expressed as their mass) remains challenging.

  11. Nitric oxide mediates the fungal elicitor-induced puerarin biosynthesis in Pueraria thomsonii Benth. suspension cells through a salicylic acid (SA)-dependent and a jasmonic acid (JA)-dependent signal pathway

    Institute of Scientific and Technical Information of China (English)

    XU Maojun; DONG Jufang; ZHU Muyuan

    2006-01-01

    Nitric oxide (NO) has emerged as a key signaling molecule in plant secondary metabolite biosynthesis recently. In order to investigate the molecular basis of NO signaling in elicitor-induced secondary metabolite biosynthesis of plant cells, we determined the contents of NO, salicylic acid (SA), jasmonic acid (JA), and puerarin in Pueraria thomsonii Benth. suspension cells treated with the elicitors prepared from cell walls of Penicillium citrinum. The results showed that the fungal elicitor induced NO burst, SA accumulation and puerarin production of P. thomsonii Benth. cells. The elicitor-induced SA accumulation and puerarin production was suppressed by nitric oxide specific scavenger cPITO, indicating that NO was essential for elicitor-induced SA and puerarin biosynthesis in P. thomsonii Benth. cells. In transgenic NahG P. thomsonii Benth. cells, the fungal elicitor also induced puerarin biosynthesis, NO burst, and JA accumulation, though the SA biosynthesis was impaired. The elicitor-induced JA accumulation in transgenic cells was blocked by cPITO, which suggested that JA acted downstream of NO and its biosynthesis was controlled by NO. External application of NO via its donor sodium nitroprusside (SNP) enhanced puerarin biosynthesis in transgenic NahG P. thomsonii Benth. cells, and the NO-triggered puerarin biosynthesis was suppressed by JA inhibitors IBU and NDGA, which indicated that NO induced puerarin production through a JA-dependent signal pathway in the transgenic cells. Exogenous application of SA suppressed the elicitor-induced JA biosynthesis and reversed the inhibition of IBU and NDGA on elicitor-induced puerarin accumulation in transgenic cells, which indicated that SA inhibited JA biosynthesis in the cells and that SA might be used as a substitute for JA to mediate the elicitor- and NO-induced puerarin biosynthesis. It was, therefore, concluded that NO might mediate the elicitor-induced puerarin biosynthesis through SA- and JA-dependent signal

  12. DNA fragmentation dynamics allows the assessment of cryptic sperm damage in human: Evaluation of exposure to ionizing radiation, hyperthermia, acidic pH and nitric oxide

    Energy Technology Data Exchange (ETDEWEB)

    Santiso, Rebeca; Tamayo, Maria [Laboratorio de Genetica Molecular y Radiobiologia, Centro Oncologico de Galicia, Doctor Camilo Veiras 1, 15009-A Coruna (Spain); Genetics Unit, INIBIC-Complejo Hospitalario Universitario A Coruna (CHUAC), As Xubias, 84, 15006-A Coruna (Spain); Gosalvez, Jaime [Genetics Unit, Facultad de Biologia, Universidad Autonoma de Madrid, Ciudad Universitaria de Cantoblanco, 28049 Madrid (Spain); Johnston, Steve [School of Agriculture and Food Science, University of Queensland, Gatton 4343 (Australia); Marino, Alfonso [Servicio de Oncologia Radioterapica, Centro Oncologico de Galicia, Doctor Camilo Veiras 1, 15009-A Coruna (Spain); Fernandez, Carlos; Losada, Carlos [Servicio de Radiofisica, Centro Oncologico de Galicia, Doctor Camilo Veiras 1, 15009-A Coruna (Spain); Fernandez, Jose Luis, E-mail: Jose.Luis.Fernandez.Garcia@sergas.es [Laboratorio de Genetica Molecular y Radiobiologia, Centro Oncologico de Galicia, Doctor Camilo Veiras 1, 15009-A Coruna (Spain); Genetics Unit, INIBIC-Complejo Hospitalario Universitario A Coruna (CHUAC), As Xubias, 84, 15006-A Coruna (Spain)

    2012-06-01

    Sperm DNA fragmentation (SDF) is not a static seminal parameter, since the longevity of sperm DNA decreases progressively with time following ejaculation or thawing. While the dynamics of SDF is a species-specific characteristic, in the case of humans, there is still significant variation within patients. To evaluate the suitability of the dynamic SDF assay to assess the adverse effects of agents that cause genetic damage, fresh semen samples from different donors were exposed in vitro to (1) increasing acute doses of ionizing radiation, (2) elevated temperature (41 Degree-Sign C and 45 Degree-Sign C), (3) acidic pH (pH 4) and (4) the nitric oxide (NO) donor sodium nitroprusside (SNP). Sperm DNA fragmentation was analyzed after an incubation period of chronic (24 h), or acute (1 h) exposure to each treatment followed by incubation at 37 Degree-Sign C over a period of 24 h. SDF was assessed using the sperm chromatin dispersion (SCD) test. Dynamic SDF for each treatment was analyzed using Kaplan-Meier survival curves. All agents, except for ionizing radiation, accelerated SDF kinetics following chronic exposure over a 24 h period. Transient exposure to NO and heat but not acidic pH increased the basal (T0) level of SDF. Despite the removal of the three toxicants, the remaining sperm following acute exposure showed a decrease in their expected DNA longevity. It is concluded that the assessment of sperm DNA fragmentation dynamics is an effective methodological approach for revealing latent damage associated with toxicants that is not initially expressed following a single initial observation of SDF.

  13. 硝酸浸取磷矿制轻质碳酸钙工艺研究%Preparation of light calcium carbonate by nitric acid leaching phosphate ore

    Institute of Scientific and Technical Information of China (English)

    胡兆平; 贾洪秀; 庞世花; 刘阳; 贾亮

    2013-01-01

    Calcium nitrate crystal can be obtained by freezing crystallization method from acid solution acquired from nitric acid extracting phosphate rock.After that,light calcium carbonate was prepared by carbonization reaction between ammonium hydrogen carbonate and calcium nitrate crystal.Results show that,the initial carbonization reaction temperature was the normal temperature,mass fraction of calcium nitrate solution was about 23%,ammonium hydrogen carbonate and ammonia dosages were both 110% of theoretical addition amounts,and products were washed by four times of product weight washing water.All quality indexes of the product can meet the standard of Industrial Precipitated Calcium Carbonate,HG/T 2226-2000.%硝酸萃取磷矿后的酸解液,通过冷冻结晶法得到硝酸钙晶体,然后以硝酸钙为原料,通过加入碳酸氢铵进行碳化制取轻质碳酸钙.结果表明,碳化反应的初始反应温度为常温,硝酸钙溶液的质量分数为23%左右,碳酸氢铵和氨水按理论加入量的110%进行反应,用产品质量的4倍洗水量洗涤产品,制备的轻质碳酸钙产品各项指标均达到HG/T 2226-2000《工业沉淀碳酸钙》标准的要求.

  14. COPPER AMINE OXIDASE1 (CuA01)of Arabidopsis thaliana Contributes to Abscisic Acid-and Polyamine-Induced Nitric Oxide Biosynthesis and Abscisic Acid Signal Transduction

    Institute of Scientific and Technical Information of China (English)

    Rinukshi Wimalasekera; Corina Villar; Tahmina Begum; Günther F. E. Scherer

    2011-01-01

    Polyamines (PA), polyamine oxidases, copper amine oxidases, and nitric oxide (NO)play important roles in physiology and stress responses in plants. NO biosynthesis as a result of catabolism of PA by polyamine oxidases and copper amine oxidases may explain in part PA-mediated responses. Involvement of a copper amine oxidase gene, COPPER AMINE OXIDASE1 (CuA01), of Arabidopsis was tested for its role in stress responses using the knockouts cuaol.1 and cuaol-2. PA-induced and ABA-induced NO production investigated by fluorometry and fluorescence microscopy showed that the cuaol-1 and cuaol-2 are impaired in NO production, suggesting a function of CuAO1 in PA and ABA-mediated NO production. Furthermore, we found a PA-dependent increase in protein S-nitrosylation. The addition of PA and ABA also resulted in HO increases, cuaol-1 and cuaol-2 showed less sensitivity to exogenous ABA supplementation during ger-mination, seedling establishment, and root growth inhibition as compared to wild-type. In response to ABA treatment,expression levels of the stress-responsive genes RD29A and ADH1 were significantly lower in the knockouts. These obser-vations characterize cuaol-1 and cuaol-2 as ABA-insensitive mutants. Taken together, our findings extend the ABA signal transduction network to include CuAO1 as one potential contributor to enhanced NO production by ABA.

  15. Effects of a New Glutamic Acid Derivative on Myocardial Contractility of Stressed Animals under Conditions of Nitric Oxide Synthesis Blockade.

    Science.gov (United States)

    Tyurenkov, I N; Perfilova, V N; Sadikova, N V; Berestovitskaya, V M; Vasil'eva, O S

    2015-07-01

    Glufimet (glutamic acid derivative) in a dose of 28.7 mg/kg limited the reduction of the cardiac functional reserve in animals subjected to 24-h stress under conditions of nonselective NO synthase blockade with L-NAME (10 mg/kg). Adrenoreactivity and increased afterload tests showed that the increment of myocardial contraction/relaxation rates, left-ventricular pressure, and HR were significantly higher in glufimet-treated stressed animals with NO synthesis blockade than in animals which received no glufimet. The efficiency of glufimet was higher than that of phenibut (the reference drug).

  16. Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; comparison of a nitric acid in-bottle digestion procedure to other whole-water digestion procedures

    Science.gov (United States)

    Garbarino, John R.; Hoffman, Gerald L.

    1999-01-01

    A hydrochloric acid in-bottle digestion procedure is used to partially digest wholewater samples prior to determining recoverable elements by various analytical methods. The use of hydrochloric acid is problematic for some methods of analysis because of spectral interference. The inbottle digestion procedure has been modified to eliminate such interference by using nitric acid instead of hydrochloric acid in the digestion. Implications of this modification are evaluated by comparing results for a series of synthetic whole-water samples. Results are also compared with those obtained by using U.S. Environmental Protection Agency (1994) (USEPA) Method 200.2 total-recoverable digestion procedure. Percentage yields that use the nitric acid inbottle digestion procedure are within 10 percent of the hydrochloric acid in-bottle yields for 25 of the 26 elements determined in two of the three synthetic whole-water samples tested. Differences in percentage yields for the third synthetic whole-water sample were greater than 10 percent for 16 of the 26 elements determined. The USEPA method was the most rigorous for solubilizing elements from particulate matter in all three synthetic whole-water samples. Nevertheless, the variability in the percentage yield by using the USEPA digestion procedure was generally greater than the in-bottle digestion procedure, presumably because of the difficulty in controlling the digestion conditions accurately.

  17. Active-Site Models of Bacterial Nitric Oxide Reductase Featuring Tris-Histidyl and Glutamic Acid Mimics: Influence of Carboxylate Ligand on FeB Binding and Heme Fe/FeB Redox Potential

    Science.gov (United States)

    Collman, James P.; Yan, Yi-Long; Lei, Jianping; Dinolfo, Peter H.

    2008-01-01

    Active-site models of bacterial nitric oxide reductase (NOR) featuring a heme iron and a trisimidazole and a glutaric acid-bound non-heme iron (FeB) have been synthesized. These models closely replicate the proposed active site of native NORs. Examination of these models shows that the glutamic acid mimic is required for both FeB retention in the distal binding site and proper modulation of the redox potentials of both the heme and non-heme irons. PMID:16961346

  18. Characteristic and mechanism of Th{sup 4+} sorption from nitric acid solutions by rice and wheat bran

    Energy Technology Data Exchange (ETDEWEB)

    Monji, Akbar Boveiri [Kharazmi Univ., Tehran (Iran, Islamic Republic of). Faculty of Chemistry; Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of); Ghoulipour, Vanik [Kharazmi Univ., Tehran (Iran, Islamic Republic of). Faculty of Chemistry; Mallah, Mohammad Hassan [Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of)

    2015-07-01

    In line with our previously conducted researches, various instrumental methods were applied to evaluate the adsorption features and mechanism of Th{sup 4+} from highly acidic solution (4M HNO{sub 3}) by rice and wheat bran. Although the results of cation exchange confirmed the existence of ion-exchange interaction in Th{sup 4+} adsorption, it had a trivial contribution in the biosorption process. The presence of Th{sup 4+} ions on the biomass surface was obviously revealed in SEM images and EDS elemental analysis. Moreover, the linkage of C=O, O-H and N-H functional groups on the biomass surface with Th{sup 4+} ions was clearly represented in the ATR-FTIR spectroscopic analysis. Additionally, desorption studies indicated that ammonium oxalate (>81.3%) and ammonium carbonate (>75.4%) were effective in desorbing Th{sup 4+} from the biomass surface due to strong interactions of hard functional groups of C=O with Th{sup 4+}. The overall observations unfold the fact that electrostatic complexation mechanism is dominant between biomass and Th{sup 4+} ions.

  19. 稀土氟化物在硝酸中溶解性质的研究%Solubility of rare earth fluorides in nitric acid

    Institute of Scientific and Technical Information of China (English)

    仇婷婷; 彭佳; 何淑华; 郑小北; 刘玉侠; 周伟; 张岚

    2015-01-01

    Background: A varity of rare-earth fluorides can be produced with thorium uranium fuel circulating post-processing. These fluorides need to be dissolubled in solvent for seperation and contents measurement.Purpose: This paper aims to develop a fast and efficient pretreatment method to dissolve slightly soluble rare earth fluorides in nitric acid.Methods: Rare earth fluorides related to the thorium molten salt reactor (TMSR) fuel circulating post-processing including NdF3, EuF3, GdF3 and CeF3 were studied by using Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). After 2-h microwave digestion at temperature of 190 ºC, the maximum solubility of these fluorides in 10 mL nitric acid (16 mol·L−1) is determined by ICP-AES.Results: The saturated concentration varies from 2.5 g·L−1 to 3.9g·L−1, which are two or three orders of magnitude higher than their solubility reported in previous literature. The standard deviation (n=3) of measurement by ICP-AES is under 4.2% and the linear correlation coefficient (r) is in the range of 0.999 47−0.999 96.Conclusion:An efficient chemical procedure for dissolving some rare earth fluorides has been developed. It provides a reference for pretreatment of insoluble rare earth fluorides in the solid molten salt samples of thorium uranium fuel circulating post-processing.%采用微波消解-电感耦合等离子体原子发射光谱(Inductively Coupled Plasma Atomic Emission Spectroscopy, ICP-AES),系统研究了钍铀燃料循环后处理中4种典型稀土氟化物(NdF3、EuF3、GdF3、CeF3)在硝酸中的溶解性质。结果表明,在10 mL、浓度为16 mol·L−1的硝酸中,微波消解2 h,190ºC下,4种稀土氟化物的最大溶解量可达2.5−3.9 g·L−1,均比文献报道的数值高2−3个数量级;采用ICP-AES测试溶解液,线性范围0.99947−0.99996,标准偏差SD≤4.2%(n=3),该溶解方法旨在为核燃料后处理流程中含有难溶稀土氟

  20. Reduction of Biomechanical and Welding Fume Exposures in Stud Welding.

    Science.gov (United States)

    Fethke, Nathan B; Peters, Thomas M; Leonard, Stephanie; Metwali, Mahmoud; Mudunkotuwa, Imali A

    2016-04-01

    The welding of shear stud connectors to structural steel in construction requires a prolonged stooped posture that exposes ironworkers to biomechanical and welding fume hazards. In this study, biomechanical and welding fume exposures during stud welding using conventional methods were compared to exposures associated with use of a prototype system that allowed participants to weld from an upright position. The effect of base material (i.e. bare structural beam versus galvanized decking) on welding fume concentration (particle number and mass), particle size distribution, and particle composition was also explored. Thirty participants completed a series of stud welding simulations in a local apprenticeship training facility. Use of the upright system was associated with substantial reductions in trunk inclination and the activity levels of several muscle groups. Inhalable mass concentrations of welding fume (averaged over ~18 min) when using conventional methods were high (18.2 mg m(-3) for bare beam; 65.7 mg m(-3) for through deck), with estimated mass concentrations of iron (7.8 mg m(-3) for bare beam; 15.8 mg m(-3) for through deck), zinc (0.2 mg m(-3) for bare beam; 15.8 mg m(-3) for through deck), and manganese (0.9 mg m(-3) for bare beam; 1.5 mg m(-3) for through deck) often exceeding the American Conference of Governmental Industrial Hygienists Threshold Limit Values (TLVs). Number and mass concentrations were substantially reduced when using the upright system, although the total inhalable mass concentration remained above the TLV when welding through decking. The average diameters of the welding fume particles for both bare beam (31±17 nm) through deck conditions (34±34 nm) and the chemical composition of the particles indicated the presence of metallic nanoparticles. Stud welding exposes ironworkers to potentially high levels of biomechanical loading (primarily to the low back) and welding fume. The upright system used in this study improved exposure

  1. Intracerebroventricular administration of Shiga toxin type 2 altered the expression levels of neuronal nitric oxide synthase and glial fibrillary acidic protein in rat brains.

    Science.gov (United States)

    Boccoli, Javier; Loidl, C Fabián; Lopez-Costa, Juan José; Creydt, Virginia Pistone; Ibarra, Cristina; Goldstein, Jorge

    2008-09-16

    Shiga toxin (Stx) from enterohemorrhagic Escherichia coli (STEC) is the main cause of hemorrhagic colitis which may derive into Hemolytic Uremic Syndrome (HUS) and acute encephalopathy, one of the major risk factors for infant death caused by the toxin. We have previously demonstrated that intracerebroventricular administration of Stx2 causes neuronal death and glial cell damage in rat brains. In the present work, we observed that the intracerebroventricular administration of Stx2 increased the expression of glial fibrillary acidic protein (GFAP) leading to astrogliosis. Confocal microscopy showed reactive astrocytes in contact with Stx2-containing neurons. Immunocolocalization of increased GFAP and Stx2 in astrocytes was also observed. This insult in the brain was correlated with changes in the expression and activity of neuronal nitric oxide synthase (nNOS) by using the NADPH-diaphorase histochemical technique (NADPH-d HT). A significant decrease in NOS/NADPH-d-positive neurons and NOS/NADPH-d activity was observed in cerebral cortex and striatum, whereas an opposite effect was found in the hypothalamic paraventricular nucleus. We concluded that the i.c.v. administration of Stx2 promotes a typical pattern of brain injury showing reactive astrocytes and an alteration in the number and activity of nNOS/NADPH-d. According to the functional state of nNOS/NADPH-d and to brain cell morphology data, it could be inferred that the i.c.v. administration of Stx2 leads to either a neurodegenerative or a neuroprotective mechanism in the affected brain areas. The present animal model resembles the encephalopathy developed in Hemolytic Uremic Syndrome (HUS) patients by STEC intoxication.

  2. The poly-γ-d-glutamic acid capsule surrogate of the Bacillus anthracis capsule induces nitric oxide production via the platelet activating factor receptor signaling pathway.

    Science.gov (United States)

    Lee, Hae-Ri; Jeon, Jun Ho; Park, Ok-Kyu; Chun, Jeong-Hoon; Park, Jungchan; Rhie, Gi-Eun

    2015-12-01

    The poly-γ-d-glutamic acid (PGA) capsule, a major virulence factor of Bacillus anthracis, confers protection of the bacillus from phagocytosis and allows its unimpeded growth in the host. PGA capsules released from B. anthracis are associated with lethal toxin in the blood of experimentally infected animals and enhance the cytotoxic effect of lethal toxin on macrophages. In addition, PGA capsule itself activates macrophages and dendritic cells to produce proinflammatory cytokine such as IL-1β, indicating multiple roles of PGA capsule in anthrax pathogenesis. Here we report that PGA capsule of Bacillus licheniformis, a surrogate of B. anthracis capsule, induces production of nitric oxide (NO) in RAW264.7 cells and bone marrow-derived macrophages. NO production was induced by PGA in a dose-dependent manner and was markedly reduced by inhibitors of inducible NO synthase (iNOS), suggesting iNOS-dependent production of NO. Induction of NO production by PGA was not observed in macrophages from TLR2-deficient mice and was also substantially inhibited in RAW264.7 cells by pretreatment of TLR2 blocking antibody. Subsequently, the downstream signaling events such as ERK, JNK and p38 of MAPK pathways as well as NF-κB activation were required for PGA-induced NO production. In addition, the induced NO production was significantly suppressed by treatment with antagonists of platelet activating factor receptor (PAFR) or PAFR siRNA, and mediated through PAFR/Jak2/STAT-1 signaling pathway. These findings suggest that PGA capsule induces NO production in macrophages by triggering both TLR2 and PAFR signaling pathways which lead to activation of NF-kB and STAT-1, respectively.

  3. Whole Atmosphere Community Climate Model With Lower Ionospheric Chemistry: Improved Modeling of Nitric Acid and Active Chlorine During Energetic Particle Precipitation

    Science.gov (United States)

    Verronen, P. T.; Andersson, M. E.; Marsh, D. R.; Kovacs, T.; Plane, J. M. C.; Päivärinta, S. M.

    2016-12-01

    Energetic particle precipitation (EPP) and ion chemistry affect the neutral composition of the polar middle atmosphere. For example, production of odd nitrogen and odd hydrogen during EPP events can decrease ozone by tens of percent. However, the standard ion chemistry parameterizations used in atmospheric models neglect the effects on some important species, such as nitric acid. We present WACCM-D, a variant of the Whole Atmosphere Community Climate Model, which includes a set of lower ionosphere (D-region) chemistry: 307 reactions of 20 positive ions and 21 negative ions. Compared to the Sodankylä Ion and Neutral Chemistry (SIC), a state-of-the-art 1-D model of the D-region chemistry, WACCM-D represents the lower ionosphere well. Comparison of ion concentrations between the models shows that the WACCM-D bias is typically within ±10% or less below 70 km. At 70-90 km, when strong altitude gradients in ionization rates and/or ion concentrations exist, the bias can be larger for some ions but is still within tens of percent. We also compare WACCM-D results for the January 2005 solar proton event (SPE) to those from the standard WACCM and observations from the Aura/MLS and SCISAT/ACE-FTS instruments. The results indicate that WACCM-D improves the modeling of {HNO3}, {HCl}, {ClO}, {OH}, and {NOx} during the SPE. For example, Northern Hemispheric {HNO3} from WACCM-D shows an increase by two orders of magnitude at 40-70 km compared to WACCM, reaching 2.6 ppbv, in agreement with the observations. Based on our results, WACCM-D provides a state-of-the-art global representation of D-region ion chemistry and improves modeling of EPP atmospheric effects considerably.

  4. Biodegradable poly(lactic-co-glycolic acid) microspheres loaded with S-nitroso-N-acetyl-D-penicillamine for controlled nitric oxide delivery.

    Science.gov (United States)

    Lautner, Gergely; Meyerhoff, Mark E; Schwendeman, Steven P

    2016-03-10

    Nitric oxide (NO) is a fascinating and important endogenous free-radical gas with potent antimicrobial, vasodilating, smooth muscle relaxant, and growth factor stimulating effects. However, its wider biomedical applicability is hindered by its cumbersome administration, since NO is unstable especially in biological environments. In this work, to ultimately develop site-specific controlled release vehicles for NO, the NO donor S-nitroso-N-acetyl-D-penicillamine (SNAP) was encapsulated within poly(lactic-co-glycolic acid) 50:50 (PLGA) microspheres by using a solid-in-oil-in-water emulsion solvent evaporation method. The highest payload was 0.56(±0.01) μmol SNAP/mg microspheres. The in vitro release kinetics of the donor were controlled by the bioerosion of the PLGA microspheres. By using an uncapped PLGA (Mw=24,000-38,000) SNAP was slowly released for over 10days, whereas by using the ester capped PLGA (Mw=38,000-54,000) the release lasted for over 4weeks. The presence of copper ions and/or ascorbate in solution was necessary to efficiently decompose the released NO donor and obtain sustained NO release. It was also demonstrated that light can be used to induce rapid NO release from the microspheres over several hours. SNAP exhibited excellent storage stability when encapsulated in the PLGA microspheres. These new microsphere formulations may be useful for site-specific administration and treatment of pathologies associated with dysfunction in endogenous NO production, e.g. treatment of diabetic wounds, or in diseases involving other biological functions of NO including vasodilation, antimicrobial, anticancer, and neurotransmission. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Chlorogenic acid improves ex vivo vessel function and protects endothelial cells against HOCl-induced oxidative damage, via increased production of nitric oxide and induction of Hmox-1.

    Science.gov (United States)

    Jiang, Rujia; Hodgson, Jonathan M; Mas, Emilie; Croft, Kevin D; Ward, Natalie C

    2016-01-01

    Dietary polyphenols are potential contributors toward improved cardiovascular health. Coffee is one of the richest sources of dietary polyphenols in a coffee-drinking population, the most abundant form being chlorogenic acid (CGA). Endothelial dysfunction is an early and major risk factor for cardiovascular disease. Nitric oxide (NO) is a key factor in regulation of endothelial function. Heme oxygenase-1 (Hmox-1), an inducible isoform of heme oxygenase that is produced in response to stressors such as oxidative stress, may also play a role in vascular protection. The aim of this study was to investigate the effect of CGA on endothelial function with oxidant-induced damage in isolated aortic rings from C57BL mice. We further examine the mechanism by investigating cell viability, activation of eNOS and induction of Hmox-1 in human aortic endothelial cells (HAECs). We found that pretreatment of isolated aortic rings with 10-μM CGA-protected vessels against HOCl-induced endothelial dysfunction (P<0.05). Pretreatment of cultured HAECs with 10-μM CGA increased endothelial cell viability following exposure to HOCl (P<0.05). Moreover, CGA increased NO production in HAECs in a dose-dependent manner, peaking at 6 h (P<0.05). CGA at 5 μM and 10 μM increased eNOS dimerization at 6 h and induced Hmox-1 protein expression at 6 h and 24 h in HAECs. These results are consistent with the cardiovascular protective effects of coffee polyphenols and demonstrate that CGA can protect vessels and cultured endothelial cells against oxidant-induced damage. The mechanism behind the beneficial effect of CGA appears to be in part via increased production of NO and induction of Hmox-1.

  6. Emissions of nitrous acid (HONO), nitric oxide (NO) and nitrous oxide (N2O) from boreal agricultural soil - Effect of N fertilization

    Science.gov (United States)

    Bhattarai, Hem Raj; Virkajärvi, Perttu; -Yli Pirilä, Pasi; Maljanen, Marja

    2017-04-01

    There is no doubt that nitrogen (N) fertilization has crucial role in increasing food production. However, in parallel it can cause severe impact in environment such as eutrophication, surface/groundwater pollution via nitrate (NO3-) leaching and emissions of N trace gases. Fertilization increases the emissions of nitrous oxide (N2O) which is 260 stronger greenhouse gas than carbon dioxide (CO2). It also enhances the emissions of nitric oxide (NO); an oxidized and very reactive form of nitrogen which can fluctuate the ozone (O3) concentration in atmosphere and cause acidification. The effects of N- fertilization on the emission of N2O and NO from agricultural soil are well known. However, the effects of N fertilization on nitrous acid (HONO) emissions are unknown. Few studies have shown that HONO is emitted from soil but they lack to interlink fertilization and HONO emission. HONO accounts for 17-34 % of hydroxyl (OH-) radical production? in the atmosphere, OH- radicals have vital role in atmospheric chemistry; they can cause photochemical smog, form O3, oxidize volatile organic compounds and also atmospheric methane (CH4). We formulated hypothesis that N fertilization will increase the HONO emissions as it does for N2O and NO. To study this, we took soil samples from agricultural soil receiving different amount of N-fertilizer (0, 250 and 450 kg ha-1) in eastern Finland. HONO emissions were measured by dynamic chamber technique connected with LOPAP (Quma Elektronik & Analytik GmbH), NO by NOx analyzer (Thermo scientific) and static chamber technique and gas chromatograph was used for N2O gas sampling and analysis. Several soil parameters were also measured to establish the relationship between the soil properties, fertilization rate and HONO emission. This study is important because eventually it will open up more questions regarding the forms of N loss from soils and impact of fertilization on atmospheric chemistry.

  7. Testicular Nitric Oxide and Thiobarbituric Acid Reactive Substances Levels in Obstructive Azoospermia: A Possible Role in Pathophysiology of Infertility

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available Objective. The aim of the study is to evaluate the levels of nitrite/nitrate and thiobarbituric acid reactive substances (TBARS and their relationship with seminal parameters in experimental obstructive azoospermic rats to explain the possible mechanism of impaired sperm quality in obstructive azoospermia. Methods . A total of 10 male Spraque-Dawley rats underwent bilateral vas resection and ligation (Group-1=vasectomy group. The findings were compared with control group ( Group-2=sham group,n=10. Animals were sacrificed 8 weeks after surgery. Testes were removed and used for the evaluation of nitrate/nitrite and TBARS levels and for histology. Epididymal-aspirated seminal plasma was used for semen count and morphological analysis according to the Kruger criteria. Results. Testicular tissue nitrate/nitrite and TBARS levels were 35.7±3.1μ mol/g protein and 3.7±0.1 nmol/g protein in Group-1, and 19.3±0.7 μ mol/g protein and 3.1±0.1 nmol/g protein in Group-2, respectively. Both parameters showed statistical differences between the two groups. Testicular tissue nitrate/nitrite and TBARS levels showed negative and statistically significant correlations with sperm motility and morphology. Conclusions. The present study showed that testicular nitrate/nitrite and TBARS levels were increased in obstructive azoospermia. For that reason, we concluded that antioxidant treatment can be recommended to patients before sperm extraction for artificial reproduction due to obstructive infertility after vasectomy reversal.

  8. Testicular Nitric Oxide and Thiobarbituric Acid Reactive Substances Levels in Obstructive Azoospermia: A Possible Role in Pathophysiology of Infertility

    Directory of Open Access Journals (Sweden)

    M. Murad Başar

    2006-01-01

    Full Text Available Objective. The aim of the study is to evaluate the levels of nitrite/nitrate and thiobarbituric acid reactive substances (TBARS and their relationship with seminal parameters in experimental obstructive azoospermic rats to explain the possible mechanism of impaired sperm quality in obstructive azoospermia. Methods . A total of 10 male Spraque-Dawley rats underwent bilateral vas resection and ligation (Group-1=vasectomy group. The findings were compared with control group (Group-2=sham group,n=10. Animals were sacrificed 8 weeks after surgery. Testes were removed and used for the evaluation of nitrate/nitrite and TBARS levels and for histology. Epididymal-aspirated seminal plasma was used for semen count and morphological analysis according to the Kruger criteria. Results. Testicular tissue nitrate/nitrite and TBARS levels were 35.7±3.1μmol/g protein and 3.7±0.1 nmol/g protein in Group-1, and 19.3±0.7μmol/g protein and 3.1±0.1 nmol/g protein in Group-2, respectively. Both parameters showed statistical differences between the two groups. Testicular tissue nitrate/nitrite and TBARS levels showed negative and statistically significant correlations with sperm motility and morphology. Conclusions. The present study showed that testicular nitrate/nitrite and TBARS levels were increased in obstructive azoospermia. For that reason, we concluded that antioxidant treatment can be recommended to patients before sperm extraction for artificial reproduction due to obstructive infertility after vasectomy reversal.

  9. Catalytic abatement of nitrous oxide from nitric and production

    NARCIS (Netherlands)

    Oonk, J.

    1998-01-01

    Nitric acid production is identified as a main source of nitrous oxide. Options for emission reduction however are not available. TNO and Hydro Agri studied the technological and economic feasibility of catalytic decomposition of nitrous oxide in nitric acid tail-gases. Although in literature promis

  10. Studying the Risks of Cotton Cooking Oil Fumes on the Lung and Liver of Rats and the Protective Role of (Vitamin E Alphatocopherol

    Directory of Open Access Journals (Sweden)

    Fahmy GAD GAD ELsaid

    2005-12-01

    Full Text Available Fumes emitted from edible vegetable cooking oils during stir- and deep-frying are important contributors to indoor air pollution. Indoor air pollution may be increase the lung and liver cancer in Egypt in 2005. Therefore, the present study was undertaken to investigate the effects of Egyptian cotton cooking oil fumes on rats. The exposed rats for 30 and 60 days to cotton oil fumes showed a significant increase in the lung and liver malondialdehyde levels which accompanied with a significant decrease in glutathione content. Also, there was a significant decrease in lung and liver superoxide dismutase, catalase, glutathione s-transferase activities. As well as, there was a significant decrease in serum amino acids levels, lung and liver nucleic acids and total proteins. These changes were obviously after 60 days than that of 30 days of exposure. DNA change was clear in the lungs of rats after cotton oil fumes exposed as showed by the differential display technique, P53 primer which used to study the expression of the p35 gene as well as to confirm and amplify these changes after oil fumes exposure. Band with different molecular weights were observed after the exposure and in protected groups but not presented in the control. More characterization for the changes had been carried out in the animal on two levels, one the DNA using RAPD-PCR and the other on the protein level using SDS-PAGE techniques. Also, vitamin E ameliorates these abnormalities to extent limit in all cases in this work.

  11. Pulmonary effects of occupational exposure to cadmium fumes

    Energy Technology Data Exchange (ETDEWEB)

    Smetana, R.; Pilnacek, M.; Schuller, W.; Pospischil, E.; Meisinger, V.; Hochmeister, M.; Kopsa, H.; Sommer, G.

    1988-11-01

    Smelters (n=9) with occupational exposure to cadmium fumes underwent clinical routine screening, lung function test, blood gas analysis and chest-X-ray, furthermore the concentration of cadmium in blood and 24 h-urine samples was determined. The results were compared with data from controls (n=9) without specific occupational burden. Smelters showed decreased vital capacity, decreased partial pressure of oxygen and increased concentration of cadmium in blood and 24 h-urine samples compared to controls. Chronical exposure to cadmium fumes is suspected to be a causal factor for the altered data of smelters. Therefore routine-check-up in workers health control must include diagnostic means, which provide early detection of pulmonary effects.

  12. Pulmonary adverse effects of welding fume in automobile assembly welders.

    Science.gov (United States)

    Sharifian, Seyed Akbar; Loukzadeh, Ziba; Shojaoddiny-Ardekani, Ahmad; Aminian, Omid

    2011-01-01

    Welding is one of the key components of numerous manufacturing industries, which has potential physical and chemical health hazards. Many components of welding fumes can potentially affect the lung function. This study investigates the effects of welding fumes on lung function and respiratory symptoms among welders of an automobile manufacturing plant in Iran. This historical cohort study assesses 43 male welders and 129 office workers by a questionnaire to record demographic data, smoking habits, work history and respiratory symptoms as well as lung function status by spirometry. The average pulmonary function values of welders were lower relative to controls with dose-effect relationship between work duration and pulmonary function impairment. The prevalence of chronic bronchitis was higher in welders than controls. Our findings suggest that welders are at risk for pulmonary disease.

  13. Modeling of Fume Formation from Shielded Metal Arc Welding Process

    Science.gov (United States)

    Sivapirakasam, S. P.; Mohan, Sreejith; Santhosh Kumar, M. C.; Surianarayanan, M.

    2017-04-01

    In this study, a semi-empirical model of fume formation rate (FFR) from a shielded metal arc welding (SMAW) process has been developed. The model was developed for a DC electrode positive (DCEP) operation and involves the calculations of droplet temperature, surface area of the droplet, and partial vapor pressures of the constituents of the droplet to predict the FFR. The model was further extended for predicting FFR from nano-coated electrodes. The model estimates the FFR for Fe and Mn assuming constant proportion of other elements in the electrode. Fe FFR was overestimated, while Mn FFR was underestimated. The contribution of spatters and other mechanism in the arc responsible for fume formation were neglected. A good positive correlation was obtained between the predicted and experimental FFR values which highlighted the usefulness of the model.

  14. Modeling of Fume Formation from Shielded Metal Arc Welding Process

    Science.gov (United States)

    Sivapirakasam, S. P.; Mohan, Sreejith; Santhosh Kumar, M. C.; Surianarayanan, M.

    2017-01-01

    In this study, a semi-empirical model of fume formation rate (FFR) from a shielded metal arc welding (SMAW) process has been developed. The model was developed for a DC electrode positive (DCEP) operation and involves the calculations of droplet temperature, surface area of the droplet, and partial vapor pressures of the constituents of the droplet to predict the FFR. The model was further extended for predicting FFR from nano-coated electrodes. The model estimates the FFR for Fe and Mn assuming constant proportion of other elements in the electrode. Fe FFR was overestimated, while Mn FFR was underestimated. The contribution of spatters and other mechanism in the arc responsible for fume formation were neglected. A good positive correlation was obtained between the predicted and experimental FFR values which highlighted the usefulness of the model.

  15. L-theanine, a Component of Green Tea Prevents 3-Nitropropionic Acid (3-NP)-Induced Striatal Toxicity by Modulating Nitric Oxide Pathway.

    Science.gov (United States)

    Jamwal, Sumit; Kumar, Puneet

    2017-04-01

    L-theanine is unique amino acid which readily crosses blood brain barrier and possesses neuroprotective potential against neurodegenerative disorders including Huntington disease (HD). HD is characterized by selective loss of GABAergic medium spiny neurons. 3-nitropropionic acid (3-NP) induces a spectrum of HD-like neuropathology in rat striatum and widely used as experimental tool to study HD. Therefore, the present study was intended to investigate the effect of L-theanine against 3-NP-induced striatal toxicity and to explore its possible mechanism. Rats were administered with 3-NP for 21 days. L-theanine was given once a day, 1 h prior to 3-NP treatment for 21 days and L-NAME (10 mg/kg, i.p.), NO inhibitor and L-arginine (50 mg/kg; i.p.), NO precursor were administered 1 h prior to L-theanine treatment. Body weight and behavioral observation were made on weekly basis. On the 22nd day, animals were sacrificed, and the striatum was isolated for biochemical (LPO, GSH, and nitrite), pro-inflammatory cytokines and neurochemical analysis. 3-NP treatment significantly altered body weight, locomotor activity, motor coordination, mitochondrial complex-II activity, oxidative defense, pro-inflammatory mediators, and striatal neurotransmitters level. L-theanine pre-treatment (25 and 50 mg/kg/day, p.o.) significantly prevented these alterations. In addition, concurrent treatment of L-NAME with L-theanine (25 mg/kg/day, p.o.) significantly enhanced protective effect of L-theanine (25 mg/kg/day, p.o.) whereas concurrent treatment of L-arginine with L-theanine (50 mg/kg/day, p.o.) significantly ameliorated the protective effect of L-theanine (50 mg/kg/day, p.o.). The neuroprotective potential of L-theanine involves inhibition of detrimental nitric oxide production and prevention of neurotransmitters alteration in the striatum.

  16. Summary Report on Gamma Radiolysis of TBP/n-dodecane in the Presence of Nitric Acid Using the Radiolysis/Hydrolysis Test Loop

    Energy Technology Data Exchange (ETDEWEB)

    Dean R. Peterman; Bruce J. Mincher; Catherine L. Riddle; Richard D. Tillotson

    2010-08-01

    Design and installation has been completed for a state-of-the-art radiolysis/hydrolysis test loop system. The system is used to evaluate the effects of gamma radiolysis and acid hydrolysis on the stability and performance of solvent extraction process solvents. The test loop is comprised of two main sections; the solvent irradiation and hydrolysis loop and the solvent reconditioning loop. In the solvent irradiation and hydrolysis loop, aqueous and organic phases are mixed and circulated through a gamma irradiator until the desired absorbed dose is achieved. Irradiation of the mixed phases is more representative of actual conditions in a solvent extraction process. Additionally, the contact of the organic phase with the aqueous phase will subject the solvent components to hydrolysis. This hydrolysis can be accelerated by controlling the system at an elevated temperature. At defined intervals, the organic from the irradiation/hydrolysis loop will be transferred to the solvent reconditioning loop where the solvent is contacted with scrub, strip, and solvent wash solutions which simulate process flowsheet conditions. These two processes are repeated until the total desired dose is achieved. Since all viable solvent extraction components in an advanced fuel cycle must exhibit high radiolytic and hydrolytic stability, this test loop is not limited to any one solvent system but is applicable to all systems of interest. Also, the test loop is not limited to testing of process flowsheets. It is also a valuable tool in support of fundamental research on newly identified extractants/modifiers and the impact of gamma radiation on their stability in a dynamic environment. The investigation of the radiolysis of a TBP/n-dodecane process solvent in contact with aqueous nitric acid has been performed. These studies were intended to confirm/optimize the operability of the test loop system. Additionally, these data are directly applicable to numerous other solvent extraction

  17. HYDRAULIC CONDUCTIVITY OF GCL WITH BENTONITE – SILICA FUME MATRIX

    OpenAIRE

    M. Andal; Chandrasekhar, M.; G. K. Viswanadh

    2012-01-01

    This paper presents the influence of partial replacement of bentonite by silica fume which is used in the manufacture of Geosynthetic Clay Liner (GCL). Geosynthetic Clay Liners consist bentonite (Sodium Based) sandwiched between two geotextile. Benotinite, having low permeability imparts better hydraulic performance to the GCL to act as liner. In this investigation, an attempt has been made to study the hydraulic conductivity of GCL with modified Bentonite. The bentonite is partially replaced...

  18. Characterization of Group V Dubnium Homologs on DGA Extraction Chromatography Resin from Nitric and Hydrofluoric Acid Matrices

    Energy Technology Data Exchange (ETDEWEB)

    Despotopulos, J D; Sudowe, R

    2012-02-21

    somewhere between Nb and Pa. Much more recent studies have examined the properties of Db from HNO{sub 3}/HF matrices, and suggest Db forms complexes similar to those of Pa. Very little experimental work into the behavior of element 114 has been performed. Thermochromatography experiments of three atoms of element 114 indicate that the element 114 is at least as volatile as Hg, At, and element 112. Lead was shown to deposit on gold at temperatures about 1000 C higher than the atoms of element 114. Results indicate a substantially increased stability of element 114. No liquid phase studies of element 114 or its homologs (Pb, Sn, Ge) or pseudo-homologs (Hg, Cd) have been performed. Theoretical predictions indicate that element 114 is should have a much more stable +2 oxidation state and neutral state than Pb, which would result in element 114 being less reactive and less metallic than Pb. The relativistic effects on the 7p{sub 1/2} electrons are predicted to cause a diagonal relationship to be introduced into the periodic table. Therefore, 114{sup 2+} is expected to behave as if it were somewhere between Hg{sup 2+}, Cd{sup 2+}, and Pb{sup 2+}. In this work two commercially available extraction chromatography resins are evaluated, one for the separation of Db homologs and pseudo?homologs from each other as well as from potential interfering elements such as Group IV Rf homologs and actinides, and the other for separation of element 114 homologs. One resin, Eichrom's DGA resin, contains a N,N,N',N'-tetra-n-octyldiglycolamide extractant, which separates analytes based on both size and charge characteristics of the solvated metal species, coated on an inert support. The DGA resin was examined for Db chemical systems, and shows a high degree of selectivity for tri-, tetra-, and hexavalent metal ions in multiple acid matrices with fast kinetics. The other resin, Eichrom's Pb resin, contains a di-t-butylcyclohexano 18-crown-6 extractant with isodecanol solvent

  19. Detailed characterization of welding fumes in personal exposure samples

    Science.gov (United States)

    Quémerais, B.; Mino, James; Amin, M. R.; Golshahi, H.; Izadi, H.

    2015-05-01

    The objective of the project was to develop a method allowing for detailed characterization of welding particles including particle number concentration, size distribution, surface chemistry and chemical composition of individual particles, as well as metal concentration of various welding fumes in personal exposure samples using regular sampling equipment. A sample strategy was developed to evaluate the variation of the collection methods on mass concentration. Samples were collected with various samplers and filters at two different locations using our collection system. The first location was using a robotic welding system while the second was manual welding. Collected samples were analysed for mass concentration using gravimetryand metal concentration using ICP/OES. More advanced analysis was performed on selected filters using X-Ray Photoelectron Spectroscopy to determine surface composition of the particles, and X-Ray Diffraction to determine chemical composition of the fumes. Results showed that the robotic system had a lot of variation in space when the collection system was located close to the weld. Collection efficiency was found to be quite variable depending upon the type of filter. As well, metal concentrations in blank filters were dependent upon the type of filter with MCE presenting with the highest blank values. Results obtained with the XRD and XPS systems showed that it was possible to analyse a small of powdered welding fume sample but results on filters were not conclusive.

  20. The effect of thermal loading on laboratory fume hood performance.

    Science.gov (United States)

    Johnston, J D; Chessin, S J; Chesnovar, B W; Lillquist, D R

    2000-11-01

    A modified version of the ANSI/ASHRAE 110-1995 Method of Testing Performance of Laboratory Fume Hoods was used to evaluate the relationship between thermal loading in a laboratory fume hood and subsequent tracer gas leakage. Three types of laboratory burners were used, alone and in combination, to thermally challenge the hood. Heat output from burners was measured in BTU/hr, which was based on the fuel heat capacity and flow rate. Hood leakage was measured between 2824 and 69,342 BTU/hr. Sulfur hexafluoride (SF6) was released at 23.5 LPM for each level of thermal loading. Duct temperature was also measured during the heating process. Results indicate a linear relationship for both BTU/hr vs. hood leakage and duct temperature vs. hood leakage. Under these test conditions, each increase of 10,000 BTU/hr resulted in an additional 4 ppm SF6 in the manikin's breathing zone (r2 = 0.68). An additional 3.1 ppm SF6 was measured for every 25 degrees F increase in duct temperature (r2 = 0.60). Both BTU/hr and duct temperature models showed p hood leakage than duct temperature. The results of this study indicate that heat output may compromise fume hood performance. This finding is consistent with those of previous studies.

  1. The humoral immune response of mice exposed to simulated road paving-like asphalt fumes.

    Science.gov (United States)

    Anderson, Stacey E; Munson, Albert E; Tomblyn, Seth; Meade, B Jean; Diotte, Nicole M

    2008-07-01

    Asphalt is a complex mixture of organic molecules, including polycyclic aromatic hydrocarbons (PAH), which have been reported to cause serious adverse health effects in humans. Workers in manufacturing and construction trades exposed to asphalt are potentially at risk for being exposed to asphalt fumes and PAHs. Epidemiological investigations have collected mounting evidence that chemicals found in asphalt fumes present carcinogenic and possibly immunotoxic hazards. Studies evaluating the immunotoxic effects of asphalt fume are limited due to the large number of variables associated with asphalt fume exposures. This work investigates the immuno-toxic effects of road paving-like asphalt fume by analyzing the in vivo IgM response to a T-dependent antigen after exposure to whole, vapor, and particulate phase road paving-like asphalt fumes and asphalt fume condensate. Systemic exposures via intraperitoneal injection of asphalt fume condensate (at 0.625 mg/kg) and the particulate phase (at 5 mg/kg) resulted in significant reductions in the specific spleen IgM response to SRBC. Pharyngeal aspiration of the asphalt fume condensate (at 5 mg/kg) also resulted in significant suppression of the IgM response to SRBC. A significant reduction in the specific spleen IgM activity was observed after inhalation exposure to whole asphalt fumes (35 mg/m(3)) and the vapor components (11 mg/m(3)). Dermal exposures to the asphalt fume condensate resulted in significant reductions in the total (at 50 mg/kg) and specific (at 250 mg/kg) spleen IgM response to SRBC. These results demonstrate that exposure to road paving-like asphalt fumes is immunosuppressive through systemic, respiratory, and dermal routes of exposure in a murine model and raise concerns regarding the potential for adverse immunological effects.

  2. EVALUATION OF LEAKAGE FROM FUME HOODS USING TRACER GAS, TRACER NANOPARTICLES AND NANOPOWDER HANDLING TEST METHODOLOGIES

    OpenAIRE

    Dunn, Kevin H.; Tsai, Candace Su-Jung; Woskie, Susan R.; Bennett, James S.; Garcia, Alberto; Ellenbecker, Michael J.

    2014-01-01

    The most commonly reported control used to minimize workplace exposures to nanomaterials is the chemical fume hood. Studies have shown, however, that significant releases of nanoparticles can occur when materials are handled inside fume hoods. This study evaluated the performance of a new commercially available nano fume hood using three different test protocols. Tracer gas, tracer nanoparticle, and nanopowder handling protocols were used to evaluate the hood. A static test procedure using tr...

  3. Full-scale experimental research on fire fume refluence of sloped long and large curved tunnel

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    A full-scale experimental research is conducted on the fire fume refluence of a sloped long and large curved tunnel in the underground plant of a hydraulic and hydropower engineering project under three different fire powers.As a result,the eddy effect and pattern of the fire fume flow in the tunnel in case of fire is discovered and the refluence of the fume layers in case of fire is observed.Through analysis of the temperature measurement resulted in the course of the experiment,the main characteristics and performance of the fire fume refluence are discussed under the three different fire powers.

  4. Silver extraction using nitric acid from lead-zinc mine tail slag by response surface design%响应面法优化硝酸浸铅锌矿尾渣回收银工艺研究

    Institute of Scientific and Technical Information of China (English)

    杨彦松

    2011-01-01

    以硝酸浸铅锌矿尾渣回收银工艺进行了研究.以银浸出率为评价指标,探讨了硝酸质量浓度、液固比、浸出时间和浸出温度对回收银工艺的影响.在单因素实验的基础上,利用响应面法对银浸出的条件进行了优化.结果表明,当硝酸质量浓度为33.16%,液固比为16.39:1,在64.62℃的条件下浸出1.3h,该模型预测的最大银浸出率为69.73%.验证实验误差<3%,表明该模型与实际情况拟合良好.%The extraction process using nitric acid leaching silver from lead-zinc mine tail slag was studied. According to silver leaching rate using as an evaluation index, the effect of nitric acid mass concentration, the liquid-solid ratio,leaching time and leaching temperature on silver leaching rate was discussed. Based on single factor experiment, the leaching condition is further optimized by response surface method. The results showed that the largest model silver leaching rate of 69. 73% was obtained under the conditions of the concentration of 33.16% nitric acid quality and the liquid-solid ratio of 16.39:1 at 64.62 ℃ for 1.3 h. The verify error of the model was less than 3% ,and the model was fitted for the actual experiments well.

  5. 硝酸装置铂网中毒事故原因分析及解决措施%Cause Analysis of Poisoning Accident of Platinum Net in Nitric Acid Plant and Its Solution Measure

    Institute of Scientific and Technical Information of China (English)

    潘利新

    2014-01-01

    In allusion to that a relatively serious poisoning accident of platinum net existed in the nitric acid section of ammonium nitrate plant in Hei-longjiang Chemical Engineering Group Corporation, the reason of accident was analyzed and the appropriate solution measure was briefly described.%针对黑化集团硝铵厂硝酸工段一次较为严重的铂网中毒事故,分析了事故原因,简述了相应的解决措施。

  6. Corrosion Behavior of Ti-32Ta Alloy in Boiling Nitric Acid%高 Ta 钛合金在沸腾硝酸中的腐蚀行为

    Institute of Scientific and Technical Information of China (English)

    杨帆; 巨建辉; 毛小南; 吴金平; 杨英丽

    2014-01-01

    The anticorrosion titanium alloy Ti-32Ta was corroded evenly in boiling nitric acid of 8 mol/L, the corrosion behavior in boiling nitric acid has been researched.The chemical composition, structure and valence state of the surface passive film were analyzed by SEM, XRD and XPS.The results show that Ti-32Ta alloy corrosion in boiling nitric acid is a uniform behavior.Little effect is on the corrosion rate of the stable corrosion alloy when the fresh air is pumped into boiling nitric acid.The passive film of Ti-32Ta alloy is thinner, more compact and has better corrosion resistance than Ti-6Ta alloy.The valence state of Ti and Ta in the passive film of two alloys is the same, and the contents of Ta and Ta2 O5 in the Ti-32Ta alloy corrosion surface are higher than in the Ti-6Ta alloy.%对高Ta含量钛合金Ti-32Ta在8 mol/L沸腾硝酸溶液中进行了全浸腐蚀实验,研究了Ti-32Ta合金在沸腾硝酸中的腐蚀行为。采用扫描电子显微镜( SEM)、 X射线衍射( XRD)、 X射线衍射光电子能谱( XPS)等分析方法对钛合金腐蚀表面的钝化膜进行了成分、组织结构及合金价态分析。结果表明: Ti-32Ta合金在沸腾硝酸溶液中呈现均匀腐蚀行为,在介质中通入一定流量的新鲜空气对合金稳定腐蚀阶段的腐蚀速率影响不大。与Ti-6Ta合金相比, Ti-32Ta合金腐蚀后形成的钝化膜更薄更致密,耐蚀性能更好。两种合金腐蚀钝化膜中Ti和Ta的价态组成相同, Ti-32Ta合金腐蚀表面Ta及Ta2 O5的含量高于Ti-6Ta合金腐蚀表面。

  7. 利用硝酸回收机械化学活化后的硫化物浓缩液中的铅%Recovery of Lead from Sulfide Concentrate after Mechanochemical Activation Using Nitric Acid

    Institute of Scientific and Technical Information of China (English)

    A.G. Kholmogorov; O.N. Kononova; G.L. Pashkov; L.V. Shashina; V.P. Plekhanov; A.A. Sabetskiy

    2005-01-01

    Decomposition of lead sulfide concentrates in nitric acidic solutions after ferric (Ⅲ) nitrate addition and mechanical preparation has been investigated. It was found out that the decomposition can be achieved in of mechanochemical activation. The use of [Fe(NO3)3-HNO3-H2O] aqueous salt system allows the decomposition of lead sulfide concentrate at room temperature and in this case the concentration of HNO3 does not exceed mechanochemical activation of this concentrate. The insoluble residues after the leaching contain SiO2, S0, FeCO3 and PbSO4.

  8. Co-extraction and co-stripping of U(VI) and Pu(IV) using tri-iso-amyl phosphate and tri-n-butyl phosphate in n-dodecane from nitric acid media under high loading conditions

    Energy Technology Data Exchange (ETDEWEB)

    Sreenivasulu, Balija; Suresh, Ammath; Sivaraman, Nagarajan; Rao, P.R. Vasudeva [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Chemistry Group

    2016-08-01

    The extraction of Pu(IV) using 1.1 M solution of tri-iso-amyl phosphate (TiAP)/n-dodecane (DD) from plutonium nitrate solutions in nitric acid media was examined as a function of equilibrium aqueous phase metal ion concentration and equilibrium aqueous phase acidity at 303 K. The nitric acid concentration in the organic phase was measured as a function of equilibrium organic phase plutonium concentration. The co-extraction of U(VI) and Pu(IV) was studied using 1.1 M TiAP/DD system as a function of their equilibrium aqueous phase metal ion concentration and compared with 1.1 M tri-n-butyl phosphate (TBP)/n-DD system under identical conditions. Co-extraction and co-stripping of U(VI) and Pu(IV) were studied using 1.1 M TiAP/DD and 1.1 M TBP/DD systems in cross current mode to evaluate the number of stages required for the extraction and stripping of heavy metal ions (uranium and plutonium). The extraction and stripping efficiencies were calculated for both the systems. The saturation limit of the organic phase was also established in these studies.

  9. Opposing effects of D-aspartic acid and nitric oxide on tuning of testosterone production in mallard testis during the reproductive cycle

    Directory of Open Access Journals (Sweden)

    Assisi Loredana

    2008-07-01

    Full Text Available Abstract Background D-Aspartic acid (D-Asp and nitric oxide (NO play an important role in tuning testosterone production in the gonads of male vertebrates. In particular, D-Asp promotes either the synthesis or the release of testosterone, whereas NO inhibits it. In this study, we have investigated for the first time in birds the putative effects of D-Asp and NO on testicular testosterone production in relation to two phases of the reproductive cycle of the adult captive wild-strain mallard (Anas platyrhynchos drake. It is a typical seasonal breeder and its cycle consists of a short reproductive period (RP in the spring (April-May and a non reproductive period (NRP in the summer (July, a time when the gonads are quiescent. The presence and the localization of D-Asp and NO in the testis and the trends of D-Asp, NO and testosterone levels were assessed during the main phases of the bird's reproductive cycle. Furthermore, in vitro experiments revealed the direct effect of exogenously administered D-Asp and NO on testosterone steroidogenesis. Methods By using immunohistochemical (IHC techniques, we studied the presence and the distributional pattern of D-Asp and NO in the testes of RP and NRP drakes. D-Asp levels were evaluated by an enzymatic method, whereas NO content, via nitrite, was assessed using biochemical measurements. Finally, immunoenzymatic techniques determined testicular testosterone levels. Results IHC analyses revealed the presence of D-Asp and NO in Leydig cells. The distributional pattern of both molecules was in some way correlated to the steroidogenic pathway, which is involved in autocrine testosterone production. Indeed, whereas NO was present only during the NRP, D-Asp was almost exclusively present during the RP. Consistently, the high testosterone testicular content occurring during RP was coupled to a high D-Asp level and a low NO content in the gonad. By contrast, in sexually inactive drakes (NRP, the low testosterone

  10. Absorption of nitric oxide into aqueous solutions of ferrous chelates accompanied by instantaneous reaction

    NARCIS (Netherlands)

    Demmink, J.F; vanGils, I.C.F.; Beenackers, A.A C M

    1997-01-01

    The absorption of nitric oxide (NO) into aqueous solutions of ferrous chelates of nitrilotriacetic acid (NTA), ethylene diaminetetraacetic acid (EDTA), hydroxyethylenediaminetriacetic acid (HEDTA), and diethylenetriaminepentaacetic acid (DTPA) was studied in a stirred cell reactor. Experimental cond

  11. Absorption of nitric oxide into aqueous solutions of ferrous chelates accompanied by instantaneous reaction

    NARCIS (Netherlands)

    Demmink, J.F; vanGils, I.C.F.; Beenackers, A.A C M

    1997-01-01

    The absorption of nitric oxide (NO) into aqueous solutions of ferrous chelates of nitrilotriacetic acid (NTA), ethylene diaminetetraacetic acid (EDTA), hydroxyethylenediaminetriacetic acid (HEDTA), and diethylenetriaminepentaacetic acid (DTPA) was studied in a stirred cell reactor. Experimental

  12. Effect of gamma-aminobutyric acid B receptor on nitric oxide/nitric oxide synthase system during recurrent febrile seizures%反复热性惊厥过程中γ-氨基丁酸B受体对一氧化氮/一氧化氮合酶体系的调节作用

    Institute of Scientific and Technical Information of China (English)

    韩颖; 秦炯; 卜定方; 杨志仙; 常杏芝; 杜军保

    2006-01-01

    目的:探讨γ-氨基丁酸B受体(γ-aminobutyric acid B receptor,GABABR)对热性惊厥(febrile seizure,FS)大鼠一氧化氮(nitric oxide,NO)/一氧化氮合酶(nitric oxide synthase,NOS)体系表达的影响.方法:将21 d龄SD大鼠随机分为对照组、FS组、FS+巴氯芬(baclofen)组和FS+法克罗芬(phaclofen)组.采用热水浴诱导大鼠FS,隔日诱导1次,共10次.采用分光光度计法测定大鼠血浆中NO含量;用原位杂交方法观察神经元型一氧化氮合酶(neuronal nitric oxide synthase,nNOS)mRNA表达情况;用免疫组化方法观察nNOS蛋白表达情况.结果:FS+baclofen组NO含量低于FS组[(19.02±9.31)μmol/L比(40.03±9.12)μmol/L],同时nNOS蛋白和mRNA表达也较FS组减弱;而FS+phaclofen组NO含量高于FS组[(66.46±8.15)μmol/L比(40.03±9.12)μmol/L],同时nNOS蛋白和mRNA表达也较FS组增强.结论:反复热性惊厥过程中,GABABR的改变可影响NO/NOS体系的表达.

  13. Persistence of deposited metals in the lungs after stainless steel and mild steel welding fume inhalation in rats.

    Science.gov (United States)

    Antonini, James M; Roberts, Jenny R; Stone, Samuel; Chen, Bean T; Schwegler-Berry, Diane; Chapman, Rebecca; Zeidler-Erdely, Patti C; Andrews, Ronnee N; Frazer, David G

    2011-05-01

    Welding generates complex metal fumes that vary in composition. The objectives of this study were to compare the persistence of deposited metals and the inflammatory potential of stainless and mild steel welding fumes, the two most common fumes used in US industry. Sprague-Dawley rats were exposed to 40 mg/m(3) of stainless or mild steel welding fumes for 3 h/day for 3 days. Controls were exposed to filtered air. Generated fume was collected, and particle size and elemental composition were determined. Bronchoalveolar lavage was done on days 0, 8, 21, and 42 after the last exposure to assess lung injury/inflammation and to recover lung phagocytes. Non-lavaged lung samples were analyzed for total and specific metal content as a measure of metal persistence. Both welding fumes were similar in particle morphology and size. Following was the chemical composition of the fumes-stainless steel: 57% Fe, 20% Cr, 14% Mn, and 9% Ni; mild steel: 83% Fe and 15% Mn. There was no effect of the mild steel fume on lung injury/inflammation at any time point compared to air control. Lung injury and inflammation were significantly elevated at 8 and 21 days after exposure to the stainless steel fume compared to control. Stainless steel fume exposure was associated with greater recovery of welding fume-laden macrophages from the lungs at all time points compared with the mild steel fume. A higher concentration of total metal was observed in the lungs of the stainless steel welding fume at all time points compared with the mild steel fume. The specific metals present in the two fumes were cleared from the lungs at different rates. The potentially more toxic metals (e.g., Mn, Cr) present in the stainless steel fume were cleared from the lungs more quickly than Fe, likely increasing their translocation from the respiratory system to other organs.

  14. 42 CFR 84.1158 - Dust, fume, and mist tests; respirators with filters; minimum requirements; general.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Dust, fume, and mist tests; respirators with...-Purifying High Efficiency Respirators and Combination Gas Masks § 84.1158 Dust, fume, and mist tests; respirators with filters; minimum requirements; general. (a) Three respirators with cartridges containing,...

  15. Numerical investigation of turbulent diffusion in push-pull and exhaust fume cupboards.

    Science.gov (United States)

    Chern, Ming-Jyh; Cheng, Wei-Ying

    2007-08-01

    The aim of this study is to investigate airflow motions and associated pollutant distributions in fume hoods. Currently, most exhaust fume hoods are designed to use an airflow induced by a fan at the top to remove pollutants. Ambient fluids are drawn, flowing toward the opening and subsequently turning to the outlet at the roof. Pollutants are supposedly captured by the airflow and brought out from the cupboard. The present numerical study based on the finite-volume method and the standard k-epsilon turbulence model simulates flow patterns and pollutant distributions in an exhaust fume hood with and without a manikin present. Subsequently, a push-pull air curtain technique is applied to a fume cupboard. To investigate the capturing performance of a push-pull fume cupboard, numerical approaches are used to simulate flow and concentration variations. Numerical results reveal that four characteristic flow modes exist for a variety of speed ratios of push-pull flows and openings. A concave curtain mode which has a fast pull flow and a weak push flow is suggested for the operation of a push-pull fume cupboard. According to ANSI-ASHRAE Standard 110-1995, the local concentration at the specified point is fume cupboard are not affected by a manikin. In terms of those predicted results, it turns out that a push-pull fume cupboard successfully captures pollutants and prevents an operator from breathing pollutants.

  16. Micro Filler Effects of Silica-Fume on the Setting and Hardened Properties of Concrete

    Directory of Open Access Journals (Sweden)

    V.M. Sounthararajan

    2013-08-01

    Full Text Available The use of supplementary cementitious material is gaining much attention owing to its high pozzolanic property and further improvement in strength properties. Silica-fume is one among the widely used pozzolanic material which exhibits high cementing efficiency due to high silica content. This study presents comprehends a detailed insight on the hydration properties of silica fume with cement. Silica fume consists of very fine particle size and contains silica content more than 90%. The cement hydration results in the formation of calcium hydroxide and this is consumed with the addition of silica fume and results in additional calcium silicate hydrate. This compound primarily envisages the strength and improved microstructure of concrete. Addition of silica-fume fills in the spaces between cement grains. The test results showed that higher compressive strength of concrete is obtained by using 8.0% of silica-fume at 7 and 28 days was 48.25 and 55.83 MPa, respectively. This phenomenon is frequently referred to as particle packing or micro-filling. Even if silica fume did not react chemically, the micro-filler effect would lead to significant improvements in the microstructure of concrete. A comprehensive review has been carried out in this study to give a good understanding on the advantages of pozzolanic properties of silica fume in cement concrete.

  17. Indirect Prediction of Welding Fume Diffusion inside a Room Using Computational Fluid Dynamics

    Directory of Open Access Journals (Sweden)

    Sujit Dahal

    2016-05-01

    Full Text Available Welding is an important and widely used process in the manufacturing and maintenance of various works involving metals and alloys. While welding has broad applications, the welding fume generated during the process has impacts on workers’ health, which needs to be addressed. One of the major steps that can be undertaken to take care of this issue is the use of ventilation, which requires knowledge of characteristics and dispersion of the welding fume in the workers’ breathing zone. It is difficult to assess welding fume dispersion from manual measurement due to numerous welding processes and sufficient data requirement. Numerical prediction of welding fume is dubious due to several errors. This paper considers the use of numerically predicted CO2 concentrations to indirectly predict welding fume distribution in workshops. This is based on the assumption that if the particles are sufficiently small size, they follow the diffusion pattern of gases. Experiments are carried out in a room with an opening and a welding fume generation system for measurement of CO2 and fume diffusion. The results show high possibility of predicting welding fume concentration based on Computational Fluid Dynamics (CFD simulated CO2 concentration with a correlation coefficient of 0.74.

  18. Contribution to the study of the redox couple Np(VI)/Np(V) in the presence of uranium(VI) in solutions of nitric acid and nitrous acid; Contribution a l'etude du comportement redox du couple Np(VI)/Np(V) en presence d'uranium VI dans les solutions constituees d'acide nitrique et d'acide nitreux

    Energy Technology Data Exchange (ETDEWEB)

    Arpigny, S. [CEA Marcoule, Dept. de Radiochimie et Procedes, DRP, 30 (France)

    2001-07-01

    The redox behavior of the Np(VI)/Np(V) couple was the subject of a spectrometric study of the Np(VI) reduction reaction in nitric acid solutions (4 to 5 M) containing variable concentrations (1.5 to 3.5 x 10{sup -3} M) of nitrous acid. A low nitrous acid concentration and a high nitric acid concentration were found to favor the stabilization of Np(VI). The stoichiometric coefficients of nitrous acid and nitric acid in the Np(VI) reduction reaction were determined thermodynamically, although only the reaction order with respect to HNO{sub 2} could be calculated from a kinetic analysis. Adding nitrate ions to a HNO{sub 3}/HNO{sub 2} solution enhanced the stability of neptunium at oxidation state +VI, but also increased the reduction rate. When uranium(VI) was added to the HNO{sub 3}/HNO{sub 2} solutions, the total quantity of neptunium at oxidation state +V (either free or as a Np(V)-U(VI) complex) remained practically unchanged, as did the Np(VI) reduction rate. The electrochemical behavior of the Np(VI)/Np(V) couple was investigated in a weak acidic medium by voltammetry with an ultra-micro-electrode (UME). The oxidation wave limiting current variation was a linear function of the Np(V) concentration when a gold UME was used, but not with a platinum UME; the reduction wave limiting current variation versus the Np(V) concentration was linear with either gold or platinum UMEs. The presence of the Np(V)-U(VI) complex in the neptunium solutions was characterized by a shift in the normal apparent potential of the Np(VI)/Np(V) couple toward anodic potentials consistent with the previously determined values of the complexation constants. (author)

  19. Some engineering properties of heavy concrete added silica fume

    Science.gov (United States)

    Akkaş, Ayşe; Başyiǧit, Celalettin; Esen, Serap

    2013-12-01

    Many different types of building materials have been used in building construction for years. Heavy concretes can be used as a building material for critical building as it can contain a mixture of many heavy elements. The barite itself for radiation shielding can be used and also in concrete to produce the workable concrete with a maximum density and adequate structural strength. In this study, some engineering properties like compressive strength, elasticity modules and flexure strength of heavy concretes' added Silica fume have been investigated.

  20. Heterogeneous uptake of gaseous nitric acid on dolomite (CaMg(CO3)2) and calcite (CaCO3) particles: a Knudsen cell study using multiple, single, and fractional particle layers.

    Science.gov (United States)

    Johnson, Elizabeth R; Sciegienka, Joanna; Carlos-Cuellar, Sofia; Grassian, Vicki H

    2005-08-11

    In this study, the heterogeneous uptake of gaseous nitric acid on dolomite, CaMg(CO3)2, and calcite, CaCO3, particles under dry conditions at 296 K was investigated. A Knudsen cell reactor was used to measure heterogeneous uptake coefficients for these reactions. Several different experiments were performed including those on many, single, and fractional layers of particles. For experiments using multiple particle layers, the Knudsen cell data were modeled to take into account gas diffusion into the underlying layers of the sample. From this analysis, initial heterogeneous uptake coefficients, gamma(o,t), were determined to be (5 +/- 2) x 10(-4) and (2 +/- 1) x 10(-3), for dolomite and calcite, respectively, at a nitric acid concentration of 6.5 x 10(10) molecules cm(-3). For experiments that employed single or fractional particle layers, the initial heterogeneous uptake coefficient was analyzed using a recent method described in the literature. Values of the initial heterogeneous uptake coefficient using this analysis were in agreement with the above analysis and determined to be (7 +/- 4) x 10(-4) and (2 +/- 0.4) x 10(-3) for CaMg(CO3)2 and CaCO3, respectively. In addition, these results are compared to previous literature values.

  1. 硝酸装置铂网中毒的处理及预防措施%Treatment and Precautionary Measures of Platinum Gauze Poisoning in Nitric Acid Unit

    Institute of Scientific and Technical Information of China (English)

    刘多恩

    2014-01-01

    The dual-pressure dilute nitric acid production process flow sheet and affected location of platinum gauze poisoning are introduced, process conditions and causes for platinum gauze iron poisoning, oil poisoning and ash poisoning are analyzed.In connection with platinum gauze poisoning happened in nitric acid unit, relevant precautionary measures are proposed, i.e., improvement of purification degree of air filter, addition of ammonia filter or update ammonia filter type, and reduction of iron impurities sources.%介绍了双加压法稀硝酸生产工艺流程及铂网中毒后的影响部位,分析了铂网铁中毒、油中毒和灰中毒的工艺状况及原因。针对硝酸装置出现过的铂网中毒现象,提出了相应的预防措施,即提高空气过滤器的净化度、增设氨过滤器或更新氨过滤器型式、减少铁杂质的来源。

  2. Fume hoods, open canopy type--their ability to capture pollutants in various environments.

    Science.gov (United States)

    Bender, M

    1979-02-01

    Using field observations, modelling techniques and theoretical analysis, parameters describing the performance and collection efficiency of large industrial canopy fume hoods are established for, a) steady state collection of fume and b) collection of plumes with fluctuating flowrates. Hopper and pool type hoods are investigated. A baffle plate arrangement for placement within hoods is proposed. It prevents recirculation and spillage of fume. Temporary storage of fume surges within the hood is shown to be possible. At a cost of $6 per m3/hr ($10 per ft3/min) of installed fume control system capacity the arrangement promises to save millions of dollars on large new installations and to significantly improve the collection efficiency of many existing systems. A practical application of the results is proposed for the design of electric arc furnace canopy hoods.

  3. Synthetic Reference Materials Based on Polymer Films for the Control of Welding Fumes Composition

    Science.gov (United States)

    Kuznetsova, O. V.; Kuznetsova, A. N.; Begunova, L. A.

    2017-04-01

    Analysis of the current hygienic situation in the welding production showed that the intensification of welding processes involves the deterioration of air quality, which negatively affects the welders health. Welders are exposed to a variety of metal fumes, including manganese that may elevate the risk for neurological diseases. The control of metals concentration in the air of the working area is difficult due to the lack of reference materials. The creation of reference materials of welding fumes composition is a challenge due to chemical characteristics of their physical properties. Synthetic samples in a form of the polymer film containing powder particles of welding fumes were create. Studies on the selection of the polymer were done. Experiments proved that the qualitative materials of synthetic welding fumes are obtained by using polyvinyl alcohol. The metals concentration in the samples was determined by X-ray fluorescence analysis. The obtained data demonstrates indirectly the uniform distribution of welding fumes powder particles on the polymer film.

  4. Influence of Silica Fume on Corrosion Behaviour of Reinforced Steel in Different Media

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Electrochemical and corrosion behaviour of reinforced steel embedded in cement pastes incorporating differentamounts of silica fume as a partial replacement of cement has been studied in chloride and sulphate solutionsby using different electrochemical techniques. The results indicate that, while steel passivity degree is Iow in thecontrol samples upon soaking in the corrosive media, it has been high in samples incorporating silica fume andincreased with increasing silica fume content. The improvement effect of silica fume may be attributed to the poresolution structure of the cement paste, which limits the mobility of aggressive ions near the surface of the steel. Themechanism of steel corrosion due to chloride and sulphate attack and passivation effect of silica fume are discussed.

  5. Monolithic stationary phases with incorporated fumed silica nanoparticles. Part I. Polymethacrylate-based monolithic column with incorporated bare fumed silica nanoparticles for hydrophilic interaction liquid chromatography.

    Science.gov (United States)

    Aydoğan, Cemil; El Rassi, Ziad

    2016-05-01

    Fumed silica nanoparticles (FSNPs), were incorporated for the first time into a polymethacrylate monolithic column containing glyceryl monomethacrylate (GMM) and ethylene dimethacrylate (EDMA) in order to develop a new monolithic column for hydrophilic interaction high performance liquid chromatography (HILIC). When compared to poly(GMM-EDMA) monolithic column without FSNPs, the same monolithic column with incorporated FSNPs yielded important effects on HILIC separations. The effects of monomers and FSNPs content of the polymerization mixture on the performance of the monolithic column were examined in details, and the optimized stationary phase was investigated over a wide range of mobile phase composition with polar acidic, weakly basic and neutral analytes including hydroxy benzoic acids, nucleotides, nucleosides, dimethylformamide, formamide and thiourea. The retention of these analytes was mainly controlled by hydrophilic interactions with the FSNPs and electrostatic repulsion from the negatively charged silica surface in the case of hydroxy benzoic acids and nucleotides. The electrostatic repulsion was minimized by decreasing the pH of the aqueous component of the mobile phase, which in turn enhanced the retention of acidic solutes. Nucleotides were best separated using step gradient elution at decreasing pH as well as ACN concentration in the mobile phase. Improved peak shape and faster analysis of nucleosides were attained by a fast linear gradient elution with a shallow decrease in the ACN content of the ACN-rich mobile phase. The run-to-run and column-to-column reproducibility were satisfactory. The percent relative standard deviations (%RSDs) for the retention times of tested solutes were lower than 2.5% under isocratic conditions and lower than 3.5 under gradient conditions.

  6. High performance superplasticized silica fume mortars for ferrocement works

    Directory of Open Access Journals (Sweden)

    Rathish Kumar P.

    2010-01-01

    Full Text Available Ferrocement works demand cement mortars of good workability and high strength. Reduction in water-cement ratio combined with a refined pore structure increases the compressive strength in addition to the enhancement of durability characteristics, but the workability decreases. Workability becomes important, as the mortar has to easily penetrate between the layers of the mesh wires. A reasonably workable high strength cement mortar can be obtained by using a high cement content coupled with the use of superplasticizers. These were also found to retain the cohesiveness and check undesirable bleeding and segregation. An experimental program was conducted to study the functional efficacy of an SNF condensate used as a water reducing superplasticizer. The compressive strength and flow characteristics of the mortars were determined to decide their suitability for ferrocement works. The parameters included the mix proportions, the grade of cement, age of curing and the dosage of superplasticizer. It was concluded from the study that the addition of an optimum dosage of superplasticizer improved the workability and strength characteristics of silica fume mortars. There was a late gain in the compressive strength of silica fume mortars.

  7. Evaluation of one-step luminescent cyanoacrylate fuming.

    Science.gov (United States)

    Khuu, Alicia; Chadwick, Scott; Spindler, Xanthe; Lam, Rolanda; Moret, Sébastien; Roux, Claude

    2016-06-01

    One-step luminescent cyanoacrylates have recently been introduced as an alternative to the conventional cyanoacrylate fuming methods. These new techniques do not require the application of a luminescent post-treatment in order to enhance cyanoacrylate-developed fingermarks. In this study, three one-step polymer cyanoacrylates: CN Yellow Crystals (Aneval Inc.), PolyCyano UV (Foster+Freeman Ltd.) and PECA Multiband (BVDA), and one monomer cyanoacrylate: Lumikit™ (Crime Scene Technology), were evaluated against a conventional two-step cyanoacrylate fuming method (Cyanobloom (Foster+Freeman Ltd.) with rhodamine 6G stain). The manufacturers' recommended conditions or conditions compatible with the MVC™ 1000/D (Foster+Freeman Ltd.) were assessed with fingermarks aged for up to 8 weeks on non-porous and semi-porous substrates. Under white light, Cyanobloom generally gave better development than the one-step treatments across the substrates. Similarly when viewed under the respective luminescent conditions, Cyanobloom with rhodamine 6G stain resulted in improved contrast against the one-step treatments except on polystyrene, where PolyCyano UV and PECA Multiband gave better visualisation. Rhodamine 6G post-treatment of one-step samples did not significantly enhance the contrast of any of the one-step treatments against Cyanobloom/rhodamine 6G-treated samples.

  8. Testing procedures to determine the toxicity of blast fumes

    Energy Technology Data Exchange (ETDEWEB)

    Carbonel, P.; Bigourd, J. (Centre d' Etudes et Recherches des Charbonnages de France (CERCHAR), 60 - Verneuil-en-Halatte:

    1980-05-01

    Several methods are available in CERCHAR to determine the production of toxic gases from a shot of explosives: blasting of 50 g or 100 g of explosives in a 115 l bomb usually in the presence of sand and in a nitrogen atmosphere, blasting from 0.5 kg to 1 kg of explosive in a 15 m/sup 3/ chamber in the presence of air, under variable confinement (suspended charge or charge in a test mortar with or without stemming and possibly with a sheath). The test results show that the production of toxic gases depends to a great extent on the blasting conditions: type of detonation of the explosive, work done by the fumes, possible reactions of the fumes with atmospheric oxygen or with materials in contact with the explosive (cartridge material, stemming, sheath). It appears that the method consisting in blasting of explosives in a steel mortar with stemming in the 15 m/sup 3/ chamber gives results most closely related to those obtained in underground blasting. Therefore this method seems prefereble.

  9. Palmitic acid exerts pro-inflammatory effects on vascular smooth muscle cells by inducing the expression of C-reactive protein, inducible nitric oxide synthase and tumor necrosis factor-α.

    Science.gov (United States)

    Wu, Di; Liu, Juntian; Pang, Xiaoming; Wang, Shuyue; Zhao, Jingjing; Zhang, Xiaolu; Feng, Liuxin

    2014-12-01

    Atherosclerosis is a chronic inflammatory disease in the vessel, and inflammatory cytokines play an important role in the inflammatory process of atherosclerosis. A high level of free fatty acids (FFAs) produced in lipid metabolism disorders are known to participate in the formation of atherosclerosis through multiple bioactivities. As the main saturated fatty acid in FFAs, palmitic acid stimulates the expression of inflammatory cytokines in macrophages. However, it is unclear whether palmitic acid exerts a pro-inflammatory effect on vascular smooth muscle cells (VSMCs). The purpose of the present study was to observe the effect of palmitic acid on the expression of C-reactive protein (CRP), tumor necrosis factor α (TNF-α) and inducible nitric oxide synthase (iNOS) in VSMCs. Rat VSMCs were cultured, and palmitic acid was used as a stimulant for CRP, TNF-α and iNOS expression. mRNA expression was assayed with reverse transcription-polymerase chain reaction, and protein expression was detected with western blot analysis and immunocytochemistry. The results showed that palmitic acid significantly stimulated mRNA and protein expression of CRP, TNF-α and iNOS in VSMCs in time- and concentration-dependent manners, and therefore, palmitic acid is able to exert a pro-inflammatory effect on VSMCs via stimulating CRP, TNF-α and iNOS expression. The findings provide a novel explanation for the direct pro-inflammatory and atherogenic effects of palmitic acid, and for the association with metabolic syndrome, such as type 2 diabetes mellitus, obesity and atherosclerosis. Therefore, the intervention with anti-inflammatory agents may effectively delay the formation and progression of atherosclerosis in patients with metabolic syndrome.

  10. Useful and harmful effects of nitric oxide

    Directory of Open Access Journals (Sweden)

    Jović Slavoljub

    2013-01-01

    Full Text Available In living sistems synthesis of nitric oxide occurs during metabolism from Larginin, nitrite and ascorbate. Being very significant carrier of information within numerous both physiological and pathological proceses in mammals' organisms, nitric oxid could possibly be useful as well as harmful. Nitric oxide synthesis is adjuvant in a healthy organism because it represents the basic molecule for understanding numerous processes in neurology, psychology, immunology and varios related fields. In other words, nitric oxide participate in number of physiological processes, such as: transmission of nerve signals (neurotransmitter role, regulation of smooth muscle tissue relaxation (eg. vasodilatation, peristaltic movements, immunomodulation, mastocyte activation, development of inflammatory response, apoptosis regulation, angiogenesis and glucose metabolism, normal heart functioning and antioxidation role. Besides being useful, nitric oxide can be harmful as well, because it has one unpaired electron, so consequently it is susceptible to oxidation becoming a stable free radical. Being such, it reacts quickly with superoxide-anion radical, givind at first an extremely reactive peroxinitrite anion, and subsequently peroxidnitrite acid. This acid is very dangerous causing thiol groups oxidation, tyrosine and phenylalanine nitrosylation, lipid oxidation, DNK chain splitting, nitrification and nucleic bases deamination. These damages of macromolecules can cause a series of undesirable changes which subsequently distub functions of molecules, and thus of cells, tissues and even organs. [Projekat Ministarstva nauke Republike Srbije, br. 173034 i br. 31085

  11. Processes regulating nitric oxide emissions from soils

    DEFF Research Database (Denmark)

    Pilegaard, Kim

    2013-01-01

    Nitric oxide (NO) is a reactive gas that plays an important role in atmospheric chemistry by influencing the production and destruction of ozone and thereby the oxidizing capacity of the atmosphere. NO also contributes by its oxidation products to the formation of acid rain. The major sources...

  12. Supplementary catechins attenuate cooking-oil-fumes-induced oxidative stress in rat lung.

    Science.gov (United States)

    Yang, Chao-Huei; Lin, Chun-Yao; Yang, Joan-Hwa; Liou, Shaw-Yih; Li, Ping-Chia; Chien, Chiang-Ting

    2009-06-30

    Cooking-oil-fumes containing toxic components may induce reactive oxygen species (ROS) to oxidize macromolecules and lead to acute lung injury. Our previous study showed that a decaffineated green tea extract containing (+)-catechin, (-)-epicatechin, (+)-gallocatechin, (-)-epigallocatechin, (-)-epicatechin gallate, and (-)-epigallocatechin gallate can inhibit oxidation, inflammation, and apoptosis. We determined whether the catechins supplement may reduce cooking-oil-fumes-induced acute lung injury in rat. In the urethane-anesthetized Wistar rat subjected to 30-120 min of cooking-oil-fumes exposure, blood ROS significantly increased in the recovery stage. After 30-min cooking-oil-fumes exposure, the enhanced blood ROS level further increased in a time-dependent manner during the recovery stage (321 +/- 69 counts/10 s after 1 h, 540 +/- 89 counts/10 s after 2 h, and 873 +/- 112 counts/10 s after 4 h). Four hours after 30-min cooking-oil-fumes exposure, lung lavage neutrophils and ROS as well as lung tissue dityrosine and 4-hydroxy-2-nonenal increased significantly. Two weeks of catechins supplememnt significantly reduced the enhanced lavage ROS, lung dityrosine and 4-hydroxy-2-nonenal level. Cooking-oil-fumes-induced oxidative stress decreased lung Bcl-2/Bax ratio and HSP70 expression, but catechins treatment preserved the downregulation of Bcl-2/Bax ratio and HSP70 expression. We conclude that catechins supplement attenuates cooking-oil-fumes-induced acute lung injury via the preservation of oil-smoke induced downregulation of antioxidant, antiapoptosis, and chaperone protein expression.

  13. Gaps in scientific knowledge about the carcinogenic potential of asphalt/bitumen fumes.

    Science.gov (United States)

    Schulte, Paul A

    2007-01-01

    Despite a relatively large body of published research, the potential carcinogenicity of asphalt/bitumen fumes is still a vexing question. Various uncertainties and gaps in scientific knowledge need to be addressed. These include uncertainties in chemistry, animal studies, and human studies. The chemistry of asphalt/bitumen fumes is complex and varies according to the source of the crude oil and the application parameters. The epidemiological studies, while showing weak evidence of lung cancer, are inconsistent and many confounding factors have not been addressed. Studies of animal exposure are also inconsistent regarding laboratory and field-generated fumes. There is a need for further human studies that address potential confounding factors such as smoking, diet, coal tar, and diesel exposures. Animal inhalation studies need to be conducted with asphalt/bitumen fumes that are chemically representative of roofing and paving fumes. Underlying all of this is the need for continued characterization of fumes so their use in animal and field studies can be properly assessed. Nonetheless, uncertainties such as these should not preclude appropriate public health actions to protect workers in the even that asphalt fumes are found to be a carcinogenic hazard.

  14. Nitric oxide supersensitivity

    DEFF Research Database (Denmark)

    Olesen, J; Iversen, Helle Klingenberg; Thomsen, L L

    1993-01-01

    in a double blind design to 17 migraine patients, 17 age and sex matched healthy controls and 9 subjects with tension-type headache. The nitroglycerin-induced headache was significantly more severe in migraine sufferers, lasted longer and fulfilled diagnostic criteria for migraine more often. We have...... previously shown a similar supersensitivity to histamine which in human cerebral arteries activates endothelial H1 receptors and causes endothelial production of nitric oxide. Migraine patients are thus supersensitive to exogenous nitric oxide from nitroglycerin as well as to endothelially produced nitric...

  15. The effects of utilizing silica fume in Portland Cement Pervious Concrete

    Science.gov (United States)

    Mann, Daniel Allen

    Silica fume has long been used as a supplementary cementing material to provide a high density, high strength, and durable building material. Silica fume has a particle size a fraction of any conventional cement, which allows it to increase concrete strength by decreasing the porosity especially near the aggregates surface. Because Portland Cement Pervious Concrete (PCPC) has a smaller bond area between aggregate and paste, silica fume has significant impacts on the properties of the PCPC. The research in this paper studies the workability of a cement paste containing silica fume in addition to analyzing the results of testing on Portland Cement Pervious Concrete mixtures that also contained silica fume. Testing conducted included a study of the effects of silica fume on cement's rheological properties at various dosage rates ranging from zero to ten percent by mass. It was determined that silica fume has negligible effects on the viscosity of cement paste until a dosage rate of five percent, at which point the viscosity increases rapidly. In addition to the rheological testing of the cement paste, trials were also conducted on the pervious concrete samples. Sample groups included mixes with river gravel and chipped limestone as aggregate, washed and unwashed, and two different void contents. Workability tests showed that mixtures containing a silica fume dosage rate of 5 percent or less had comparable or slightly improved workability when compared to control groups. Workability was found to decrease at a 7 percent dosage rate. Samples were tested for compressive strength at 7 and 28 days and splitting tensile strength at 28 days. It was found in most sample groups, strength increased with dosage rates of 3 to 5 percent but often decreased when the dosage reached 7 percent. Abrasion testing showed that both samples containing washed aggregate and samples containing silica fume exhibited a reduced mass loss.

  16. Modifying welding process parameters can reduce the neurotoxic potential of manganese-containing welding fumes.

    Science.gov (United States)

    Sriram, Krishnan; Lin, Gary X; Jefferson, Amy M; Stone, Samuel; Afshari, Aliakbar; Keane, Michael J; McKinney, Walter; Jackson, Mark; Chen, Bean T; Schwegler-Berry, Diane; Cumpston, Amy; Cumpston, Jared L; Roberts, Jenny R; Frazer, David G; Antonini, James M

    2015-02-03

    Welding fumes (WF) are a complex mixture of toxic metals and gases, inhalation of which can lead to adverse health effects among welders. The presence of manganese (Mn) in welding electrodes is cause for concern about the potential development of Parkinson's disease (PD)-like neurological disorder. Consequently, from an occupational safety perspective, there is a critical need to prevent adverse exposures to WF. As the fume generation rate and physicochemical characteristics of welding aerosols are influenced by welding process parameters like voltage, current or shielding gas, we sought to determine if changing such parameters can alter the fume profile and consequently its neurotoxic potential. Specifically, we evaluated the influence of voltage on fume composition and neurotoxic outcome. Rats were exposed by whole-body inhalation (40 mg/m(3); 3h/day × 5 d/week × 2 weeks) to fumes generated by gas-metal arc welding using stainless steel electrodes (GMA-SS) at standard/regular voltage (25 V; RVSS) or high voltage (30 V; HVSS). Fumes generated under these conditions exhibited similar particulate morphology, appearing as chain-like aggregates; however, HVSS fumes comprised of a larger fraction of ultrafine particulates that are generally considered to be more toxic than their fine counterparts. Paradoxically, exposure to HVSS fumes did not elicit dopaminergic neurotoxicity, as monitored by the expression of dopaminergic and PD-related markers. We show that the lack of neurotoxicity is due to reduced solubility of Mn in HVSS fumes. Our findings show promise for process control procedures in developing prevention strategies for Mn-related neurotoxicity during welding; however, it warrants additional investigations to determine if such modifications can be suitably adapted at the workplace to avert or reduce adverse neurological risks.

  17. 硝酸浸出失效催化剂提取银的实验研究%Experimental Study on Extracting Silver by Leaching Spent Catalyst with Nitric Acid

    Institute of Scientific and Technical Information of China (English)

    范兴祥; 董海刚; 吴跃东; 付光强; 刘杨; 赵家春; 吴晓峰; 昝林寒; 李博捷

    2013-01-01

    采用硝酸浸出失效催化剂提取其中金属银,研究了失效催化剂粒度、硝酸用量、浸出温度、浸出时间和洗涤次数等因素对银浸出率的影响.结果表明,失效催化剂粒度对银浸出率影响显著,增加洗涤次数有利于提高银的浸出率.通过实验,确定了合理的工艺参数为:硝酸用量为失效催化剂质量的70%、浸出温度65℃、浸出时间3h、催化剂粒度为0.125 ~0.18 mm、搅拌洗涤3次.在此条件下,银的浸出率为99.52%,浸出渣含银0.072%.综合实验结果表明,从失效催化剂到海绵银产品,银的直收率达到99.27%.%Spent catalyst was leached by nitric acid to extract metallic silver from it. The effects of the particle size of spent catalyst, the dosage of nitric acid, leaching temperature, leaching time and washing times on the leaching rate of silver were investigated. The results showed that the particle size of spent catalyst has great effect on the leaching rate of silver which would also be improved by increasing washing times. Based on experiments, technological parameters are reasonably determined as follows; the dosage of nitric acid was 70% of the quality of spent catalyst, the leaching temperature was set at 65 ℃, leaching time was 3 h, the particle size was 0.125 ~0.18 mm, the washing times were 3. Under these conditions, the leaching rate of silver was 99.52% and the content of silver in the leaching residues was 0.072%. The comprehensive experiment showed that spent catalyst can be transferred to sponge silver products with this process with direct recovery rate of silver reaching 99.27%.

  18. Removal of Methyl Orange from Aqueous Solution by Nitric Acid-Modified Titanium Ore%硝酸掺杂钛精矿吸附去除甲基橙

    Institute of Scientific and Technical Information of China (English)

    雷雪飞; 薛向欣; 杨合

    2012-01-01

    Nitric acid-modified titanium ore (NATO) sorbents were prepared by high energy ball milling process. The adsorption properties of NATO sorbents were evaluated by the decoloration efficiency of methyl orange (MO) under dark-state absorption. In the adsorption stage, L9(34) orthogonal experiments of different factors, for example, doping ratio, calcination temperature, soaking time and heating rate were performed. Based on the orthogonal experiments, the optimal operating parameters, 2.0wt % nitric acid, 300 ℃ calcination temperature, 3 h soaking time, and 10 ℃/min heating rate, are obtained. In this optimal condition, the decoloration efficiency of MO reaches 96.8 %, which is significantly better than the undoped samples. Thus, it is feasible to treat dye wastewater by these NATO sorbents.%采用高能球磨法制备了一系列硝酸掺杂的钛精矿(nitric acid-modified titanium ore,NATO)吸附材料,采用正交表L9(34)安排实验,以甲基橙(MO)溶液的脱色率作为衡量吸附剂优劣的重要判据.以硝酸掺杂比例、煅烧温度、保温时间、升温速率为因素进行正交试验,基于降低能耗和成本的考虑和综合分析的基础上,得到制备NATO吸附剂的最优工艺条件:硝酸掺杂比例为2.0%,煅烧温度为300℃,保温时间为3 h,升温速率为10℃/min.在较优工艺条件下制备的NATO吸附剂对甲基橙的脱色率达到96.8%,明显优于未掺杂样品,且沉降性能较好,易于分离,是一类有应用前景的吸附材料.

  19. Effect of Silica Fume on two-stage Concrete Strength

    Science.gov (United States)

    Abdelgader, H. S.; El-Baden, A. S.

    2015-11-01

    Two-stage concrete (TSC) is an innovative concrete that does not require vibration for placing and compaction. TSC is a simple concept; it is made using the same basic constituents as traditional concrete: cement, coarse aggregate, sand and water as well as mineral and chemical admixtures. As its name suggests, it is produced through a two-stage process. Firstly washed coarse aggregate is placed into the formwork in-situ. Later a specifically designed self compacting grout is introduced into the form from the lowest point under gravity pressure to fill the voids, cementing the aggregate into a monolith. The hardened concrete is dense, homogeneous and has in general improved engineering properties and durability. This paper presents the results from a research work attempt to study the effect of silica fume (SF) and superplasticizers admixtures (SP) on compressive and tensile strength of TSC using various combinations of water to cement ratio (w/c) and cement to sand ratio (c/s). Thirty six concrete mixes with different grout constituents were tested. From each mix twenty four standard cylinder samples of size (150mm×300mm) of concrete containing crushed aggregate were produced. The tested samples were made from combinations of w/c equal to: 0.45, 0.55 and 0.85, and three c/s of values: 0.5, 1 and 1.5. Silica fume was added at a dosage of 6% of weight of cement, while superplasticizer was added at a dosage of 2% of cement weight. Results indicated that both tensile and compressive strength of TSC can be statistically derived as a function of w/c and c/s with good correlation coefficients. The basic principle of traditional concrete, which says that an increase in water/cement ratio will lead to a reduction in compressive strength, was shown to hold true for TSC specimens tested. Using a combination of both silica fume and superplasticisers caused a significant increase in strength relative to control mixes.

  20. Effect of silica fume and SBR latex on the pasteaggregate interfacial transition zone

    Directory of Open Access Journals (Sweden)

    João Adriano Rossignolo

    2007-03-01

    Full Text Available This paper deals with the effect of silica fume and styrene-butadiene latex (SBR on the microstructure of the interfacial transition zone (ITZ between Portland cement paste and aggregates (basalt. Scanning Electron Microscope (SEM equipped with energy dispersive x ray analysis system (EDX was used to determine the ITZ thickness. In the plain concrete a marked ITZ around the aggregate particles (55 µm was observed, while in concretes with silica fume or latex SBR the ITZ was less pronounced (35-40 µm. However, better results were observed in concretes with silica fume and latex SBR (20-25 µm.

  1. Effects of cooking method, cooking oil, and food type on aldehyde emissions in cooking oil fumes.

    Science.gov (United States)

    Peng, Chiung-Yu; Lan, Cheng-Hang; Lin, Pei-Chen; Kuo, Yi-Chun

    2017-02-15

    Cooking oil fumes (COFs) contain a mixture of chemicals. Of all chemicals, aldehydes draw a great attention since several of them are considered carcinogenic and formation of long-chain aldehydes is related to fatty acids in cooking oils. The objectives of this research were to compare aldehyde compositions and concentrations in COFs produced by different cooking oils, cooking methods, and food types and to suggest better cooking practices. This study compared aldehydes in COFs produced using four cooking oils (palm oil, rapeseed oil, sunflower oil, and soybean oil), three cooking methods (stir frying, pan frying, and deep frying), and two foods (potato and pork loin) in a typical kitchen. Results showed the highest total aldehyde emissions in cooking methods were produced by deep frying, followed by pan frying then by stir frying. Sunflower oil had the highest emissions of total aldehydes, regardless of cooking method and food type whereas rapeseed oil and palm oil had relatively lower emissions. This study suggests that using gentle cooking methods (e.g., stir frying) and using oils low in unsaturated fatty acids (e.g., palm oil or rapeseed oil) can reduce the production of aldehydes in COFs, especially long-chain aldehydes such as hexanal and t,t-2,4-DDE. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. High-resolution NMR spectroscopy under the fume hood.

    Science.gov (United States)

    Küster, Simon K; Danieli, Ernesto; Blümich, Bernhard; Casanova, Federico

    2011-08-07

    This work reports the possibility to acquire high-resolution (1)H NMR spectra with a fist-sized NMR magnet directly installed under the fume hood. The small NMR sensor based on permanent magnets was used to monitor the trimerization of propionaldehyde catalyzed by indium trichloride in real time by continuously circulating the reaction mixture through the magnet bore in a closed loop with the help of a peristaltic pump. Thanks to the chemical selectivity of NMR spectroscopy the progress of the reaction can be monitored on-line by determining the concentrations of both reactant and product from the area under their respective lines in the NMR spectra as a function of time. This in situ measurement demonstrates that NMR probes can be used in chemistry laboratories, e.g. for reaction optimization, or installed at specific points of interest along industrial process lines. Therefore, it will open the door for the implementation of feedback control based on spectroscopic NMR data.

  3. 硝酸处理对竹炭曝气生物滤池性能的影响%The Influence of Nitric Acid Modification on Aerated Bio-filter with Bamboo Charcoal as Carriers

    Institute of Scientific and Technical Information of China (English)

    罗舒君

    2015-01-01

    以硝酸处理竹炭作为曝气生物滤池填料,通过研究硝酸处理对竹炭吸附性能、表面官能团等的影响,考查硝酸处理竹炭对反应器性能的影响.结果表明,硝酸处理后竹炭表面含氧官能团增加,有利于微生物的附着,仅4d就完成挂膜, 反应器对有机负荷具有良好的去除能力, 在COD负荷为1.8和4.8 kg/(m3·d) 时, 平均去除率分别为83.3%和79.4%.%In this study, the influence of nitric acid modification on the adsorption performance and the surface functional groups of the bamboo charcoal was investigated. After that, the modified bamboo charcoal was employed as the bio-filter for wastewater treatment to study its performance on dealing with organic matter. The results indicated that the nitric acid modification increased surface oxygen functional groups of bamboo charcoal. The modification also promoted the growing of the microorganism, and shortened the mature period of bio-film to 4 days. The reactor was good at COD treatment. On condition that COD volume loaded of system was 1.8 and 4.8 kg/(m3·d), the removal efficiency can reached to 83.3%and 79.4%, respectively.

  4. [Case of polymer fume fever with interstitial pneumonia caused by inhalation of polytetrafluoroethylene (Teflon)].

    Science.gov (United States)

    Son, Masami; Maruyama, Eiichi; Shindo, Yuichiro; Suganuma, Nobukazu; Sato, Shinji; Ogawa, Masahiro

    2006-07-01

    A 30-year old man was admitted to our hospital with cough, slight fever, and dyspnea that he had developed several hours after inhaling the fumes produced from a Teflon-coated pan, after evaporation of the water in the pan. Chest radiography revealed diffuse infiltrations, and a computed tomography (CT) scan revealed patchy interstitial shadows in both lungs. In pulmonary function tests, the diffusing capacity of the lungs showed a moderate decrease. Leukocytosis and slight hypoxemia were observed. The patient recovered clinically in a few days without any specific treatment. We speculated that the pulmonary problems in this patient may have been induced by the products of thermal degradation of Teflon that were present in the fumes. When Teflon is heated, the fumes generated cause an influenza like syndrome (polymer fume fever) or cause severe toxic effects such as pulmonary edema, pneumonitis, and death in the exposed individual.

  5. Improvement of RVNRL film properties by adding fumed silica and hydroxy apatite

    Directory of Open Access Journals (Sweden)

    Adul Thiangchanya

    2003-01-01

    Full Text Available The effect of adding fumed silica and hydroxy apatite to Radiation Vulcanized Natural Rubber Latex (RVNRL for improving tear strength, aging properties, degradability and water-soluble protein content of rubber films has been investigated. The addition of fumed silica and hydroxy apatite in RVNRL improves tear strength and aging properties of rubber films, whereas tensile strength and degradability of rubber films were unchanged during storage at room temperature. The water-soluble protein content in rubber films was reduced by immobilization of the fumed silica and hydroxy apatite and enhanced by addition of ZnO. This may reduce allergy problems of natural rubber latex products caused by water-soluble protein. The MST of the RVNRL with fumed silica and hydroxy apatite indicated that the latex must be used within two months after mixing because of its stability.

  6. Analysis of the Damping Behavior and Microstructure of Cement Matrix with Silane-treated Silica Fume

    Institute of Scientific and Technical Information of China (English)

    OU Jinping; LIU Tiejun; LI Jiahe

    2006-01-01

    The surface treatment of silica fume with silane coupling agent prior to incorporation in a cement mortar resulted in composites exhibiting increases in loss tangent by 5%-200% and storage modulus by 10%-20%, relative to the value obtained by using as-received silica fume. The scanning electron microscopy (SEM) images indicate that there is a morphological difference in the cement paste with treated and as-received silica fume. The X-ray diffraction (XRD), infrared (IR) spectrum analyses and mercury intrusion porosimetry (MIP) have provided evidence to understand the reaction mechanism between treated silica fume and the hydrate product of cement. This has led to the establishment of an initial microscopic model describing the damping behavior of cement matrix.

  7. Workplace field testing of the pressure drop of particulate respirators using welding fumes.

    Science.gov (United States)

    Cho, Hyun-Woo; Yoon, Chung-Sik

    2012-10-01

    In a previous study, we concluded that respirator testing with a sodium chloride aerosol gave a conservative estimate of filter penetration for welding fume aerosols. A rapid increase in the pressure drop (PD) of some respirators was observed as fumes accumulated on the filters. The present study evaluated particulate respirator PD based on workplace field tests. A field PD tester was designed and validated using the TSI 8130 Automatic Filter Tester, designed in compliance with National Institute for Occupational and Safety and Health regulation 42 CFR part 84. Three models (two replaceable dual-type filters and one replaceable single-type filter) were evaluated against CO(2) gas arc welding on mild steel in confined booths in the workplace. Field tests were performed under four airborne concentrations (27.5, 15.4, 7.9, and 2.1 mg m(-3)). The mass concentration was measured by the gravimetric method, and number concentration was monitored using P-Trak (Model 8525, TSI, USA). Additionally, photos and scanning electron microscopy-energy dispersive X-ray spectroscopy were used to visualize and analyze the composition of welding fumes trapped in the filters. The field PD tester showed no significant difference compared with the TSI tester. There was no significant difference in the initial PD between laboratory and field results. The PD increased as a function of fume load on the respirator filters for all tested models. The increasing PD trend differed by models, and PD increased rapidly at high concentrations because greater amount of fumes accumulated on the filters in a given time. The increase in PD as a function of fume load on the filters showed a similar pattern as fume load varied for a particular model, but different patterns were observed for different models. Images and elemental analyses of fumes trapped on the respirator filters showed that most welding fumes were trapped within the first layer, outer web cover, and second layer, in order, while no fumes

  8. Comparative microscopic study of human and rat lungs after overexposure to welding fume.

    Science.gov (United States)

    Antonini, James M; Roberts, Jenny R; Schwegler-Berry, Diane; Mercer, Robert R

    2013-11-01

    Welding is a common industrial process used to join metals and generates complex aerosols of potentially hazardous metal fumes and gases. Most long-time welders experience some type of respiratory disorder during their time of employment. The use of animal models and the ability to control the welding fume exposure in toxicology studies have been helpful in developing a better understanding of how welding fumes affect health. There are no studies that have performed a side-by-side comparison of the pulmonary responses from an animal toxicology welding fume study with the lung responses associated with chronic exposure to welding fume by a career welder. In this study, post-mortem lung tissue was donated from a long-time welder with a well-characterized work background and a history of extensive welding fume exposure. To simulate a long-term welding exposure in an animal model, Sprague-Dawley rats were treated once a week for 28 weeks by intratracheal instillation with 2mg of a stainless steel, hard-surfacing welding fume. Lung tissues from the welder and the welding fume-treated rats were examined by light and electron microscopy. Pathological analysis of lung tissue collected from the welder demonstrated inflammatory cell influx and significant pulmonary injury. The poor and deteriorating lung condition observed in the welder examined in this study was likely due to exposure to very high levels of potentially toxic metal fumes and gases for a significant number of years due to work in confined spaces. The lung toxicity profile for the rats treated with welding fume was similar. For tissue samples from both the welder and treated rats, welding particle accumulations deposited and persisted in lung structures and were easily visualized using light microscopic techniques. Agglomerates of deposited welding particles mostly were observed within lung cells, particularly alveolar macrophages. Analysis of individual particles within the agglomerates showed that these

  9. Transport and Deposition of Welding Fume Agglomerates in a Realistic Human Nasal Airway.

    Science.gov (United States)

    Tian, Lin; Inthavong, Kiao; Lidén, Göran; Shang, Yidan; Tu, Jiyuan

    2016-07-01

    Welding fume is a complex mixture containing ultra-fine particles in the nanometer range. Rather than being in the form of a singular sphere, due to the high particle concentration, welding fume particles agglomerate into long straight chains, branches, or other forms of compact shapes. Understanding the transport and deposition of these nano-agglomerates in human respiratory systems is of great interest as welding fumes are a known health hazard. The neurotoxin manganese (Mn) is a common element in welding fumes. Particulate Mn, either as soluble salts or oxides, that has deposited on the olfactory mucosa in human nasal airway is transported along the olfactory nerve to the olfactory bulb within the brain. If this Mn is further transported to the basal ganglia of the brain, it could accumulate at the part of the brain that is the focal point of its neurotoxicity. Accounting for various dynamic shape factors due to particle agglomeration, the current computational study is focused on the exposure route, the deposition pattern, and the deposition efficiency of the inhaled welding fume particles in a realistic human nasal cavity. Particular attention is given to the deposition pattern and deposition efficiency of inhaled welding fume agglomerates in the nasal olfactory region. For particles in the nanoscale, molecular diffusion is the dominant transport mechanism. Therefore, Brownian diffusion, hydrodynamic drag, Saffman lift force, and gravitational force are included in the model study. The deposition efficiencies for single spherical particles, two kinds of agglomerates of primary particles, two-dimensional planar and straight chains, are investigated for a range of primary particle sizes and a range of number of primary particles per agglomerate. A small fraction of the inhaled welding fume agglomerates is deposited on the olfactory mucosa, approximately in the range 0.1-1%, and depends on particle size and morphology. The strong size dependence of the deposition

  10. Alterations in welding process voltage affect the generation of ultrafine particles, fume composition, and pulmonary toxicity.

    Science.gov (United States)

    Antonini, James M; Keane, Michael; Chen, Bean T; Stone, Samuel; Roberts, Jenny R; Schwegler-Berry, Diane; Andrews, Ronnee N; Frazer, David G; Sriram, Krishnan

    2011-12-01

    The goal was to determine if increasing welding voltage changes the physico-chemical properties of the fume and influences lung responses. Rats inhaled 40 mg/m³ (3 h/day × 3 days) of stainless steel (SS) welding fume generated at a standard voltage setting of 25 V (regular SS) or at a higher voltage (high voltage SS) of 30 V. Particle morphology, size and composition were characterized. Bronchoalveolar lavage was performed at different times after exposures to assess lung injury. Fumes collected from either of the welding conditions appeared as chain-like agglomerates of nanometer-sized primary particles. High voltage SS welding produced a greater number of ultrafine-sized particles. Fume generated by high voltage SS welding was higher in manganese. Pulmonary toxicity was more substantial and persisted longer after exposure to the regular SS fume. In summary, a modest raise in welding voltage affected fume size and elemental composition and altered the temporal lung toxicity profile.

  11. Mutagenicity and polycyclic aromatic hydrocarbon content of fumes from heated cooking oils produced in Taiwan.

    Science.gov (United States)

    Chiang, T A; Wu, P F; Wang, L F; Lee, H; Lee, C H; Ko, Y C

    1997-11-28

    According to epidemiologic studies, exposure of women to fumes from cooking oils appears to be an important risk factor for lung cancer. Fume samples from three different commercial cooking oils frequently used in Taiwan were collected and analyzed for mutagenicity in the Salmonella/microsome assay. Polycyclic aromatic hydrocarbons were extracted from the samples and identified by HPLC chromatography. Extracts from three cooking oil fumes were found to be mutagenic in the presence of S9 mix. All samples contained dibenz[a,h]anthracene (DB[a,h]A) and benz[a]anthracene (B[a]A). Concentration of DB[a,h]A and B[a]A were 1.9 and 2.2 micrograms/m3 in fumes from lard oil, 2.1 and 2.3 micrograms/m3 in soybean oil, 1.8 and 1.3 micrograms/m3 in peanut oil, respectively. Benzo[a]pyrene (B[a]P) was identified in fume samples of soybean and peanut oil, in concentrations of 19.6 and 18.3 micrograms/m3, in this order. These results provide experimental evidence and support the findings of epidemiologic observations, in which women exposed to the emitted fumes of cooking oils are at increased risk of contracting lung cancer.

  12. Improved Reactivity of Fly Ash-Slag Geopolymer by the Addition of Silica Fume

    Directory of Open Access Journals (Sweden)

    N. K. Lee

    2016-01-01

    Full Text Available This study investigates the improved reactivity of a geopolymer based on a combination of fly ash and blast furnace slag (BFS by the addition of silica fume. The geopolymer was synthesized by activating a mixture of fly ash, BFS, and three different types of silica fume with alkali activator. X-ray diffraction (XRD and inductively coupled plasma-optical emission spectroscopy (ICP-OES were utilized to characterize the reaction. The silicate structure was also analyzed by nuclear magnetic resonance (NMR spectroscopy. From these results, it was found that the replacement of fly ash with the silica fume led to a significant decrease in the Q4(1Al and an increase in the Q4(2Al, Q4(3Al, and Q4(4Al. The Si/Al ratio of the aluminosilicate gel was relatively constant, ranging from 2.0 to 2.6, while the Si/Al ratio of the C-S-H gel increased with the addition of silica fume. Therefore, some of the Al dissolved from the slag contributed to the formation of aluminosilicate gel, and the remnant slag particles mostly participated in the formation of the C-(A-S-H gel with a decrease in the Q2(1Al. The increase in the reactivity of slag caused by the addition of silica fume was attributed to the reaction of the Al in the slag with the silica fume.

  13. Alternatives for Benzene in the Extraction of Bitumen Fume from Exposure Sample Media.

    Science.gov (United States)

    Sutter, Benjamin; Ravera, Christel; Hussard, Caroline; Langlois, Eddy

    2016-01-01

    Benzene is frequently used to extract collected bitumen fumes from personal sampler substrates. However, this solvent is particularly dangerous because of its carcinogenicity (group 1 of the International Agency for Research on Cancer classification). Therefore, to prevent the exposure of laboratory technicians to benzene during the fume extraction step from samplers, a compromise had to be found to identify a less toxic solvent with the same extraction capacity. To compare the extraction capacities of selected solvents, bitumen fumes were generated in the laboratory from three different batches of road surfacing bitumen collected on dedicated bitumen fume samplers. The samplers were then extracted by benzene and the solvents tested. Of 11 selected solvents less toxic than benzene and used in studies on bitumen and bitumen fume analyses, n-hexane and n-heptane were identified as alternatives to benzene. In particular, the results demonstrated that n-heptane was the best candidate solvent for benzene replacement, due to its extraction efficiency comparable to benzene for the three bitumen fumes tested and its low toxicity, which is highly compatible with benzene replacement.

  14. Enhanced Abscisic Acid-Mediated Responses in nia1nia2noa1-2 Triple Mutant Impaired in NIA/NR- and AtNOA1-Dependent Nitric Oxide Biosynthesis in Arabidopsis1[W

    Science.gov (United States)

    Lozano-Juste, Jorge; León, José

    2010-01-01

    Nitric oxide (NO) regulates a wide range of plant processes from development to environmental adaptation. Despite its reported regulatory functions, it remains unclear how NO is synthesized in plants. We have generated a triple nia1nia2noa1-2 mutant that is impaired in nitrate reductase (NIA/NR)- and Nitric Oxide-Associated1 (AtNOA1)-mediated NO biosynthetic pathways. NO content in roots of nia1nia2 and noa1-2 plants was lower than in wild-type plants and below the detection limit in nia1nia2noa1-2 plants. NIA/NR- and AtNOA1-mediated biosynthesis of NO were thus active and responsible for most of the NO production in Arabidopsis (Arabidopsis thaliana). The nia1nia2noa1-2 plants displayed reduced size, fertility, and seed germination potential but increased dormancy and resistance to water deficit. The increasing deficiency in NO of nia1nia2, noa1-2, and nia1nia2noa1-2 plants correlated with increased seed dormancy, hypersensitivity to abscisic acid (ABA) in seed germination and establishment, as well as dehydration resistance. In nia1nia2noa1-2 plants, enhanced drought tolerance was due to a very efficient stomata closure and inhibition of opening by ABA, thus uncoupling NO from ABA-triggered responses in NO-deficient guard cells. The NO-deficient mutants in NIA/NR- and AtNOA1-mediated pathways in combination with the triple mutant will be useful tools to functionally characterize the role of NO and the contribution of both biosynthetic pathways in regulating plant development and defense. PMID:20007448

  15. Enhanced abscisic acid-mediated responses in nia1nia2noa1-2 triple mutant impaired in NIA/NR- and AtNOA1-dependent nitric oxide biosynthesis in Arabidopsis.

    Science.gov (United States)

    Lozano-Juste, Jorge; León, José

    2010-02-01

    Nitric oxide (NO) regulates a wide range of plant processes from development to environmental adaptation. Despite its reported regulatory functions, it remains unclear how NO is synthesized in plants. We have generated a triple nia1nia2noa1-2 mutant that is impaired in nitrate reductase (NIA/NR)- and Nitric Oxide-Associated1 (AtNOA1)-mediated NO biosynthetic pathways. NO content in roots of nia1nia2 and noa1-2 plants was lower than in wild-type plants and below the detection limit in nia1nia2noa1-2 plants. NIA/NR- and AtNOA1-mediated biosynthesis of NO were thus active and responsible for most of the NO production in Arabidopsis (Arabidopsis thaliana). The nia1nia2noa1-2 plants displayed reduced size, fertility, and seed germination potential but increased dormancy and resistance to water deficit. The increasing deficiency in NO of nia1nia2, noa1-2, and nia1nia2noa1-2 plants correlated with increased seed dormancy, hypersensitivity to abscisic acid (ABA) in seed germination and establishment, as well as dehydration resistance. In nia1nia2noa1-2 plants, enhanced drought tolerance was due to a very efficient stomata closure and inhibition of opening by ABA, thus uncoupling NO from ABA-triggered responses in NO-deficient guard cells. The NO-deficient mutants in NIA/NR- and AtNOA1-mediated pathways in combination with the triple mutant will be useful tools to functionally characterize the role of NO and the contribution of both biosynthetic pathways in regulating plant development and defense.

  16. Genotoxic effects of fumes from asphalt modified with waste plastic and tall oil pitch.

    Science.gov (United States)

    Lindberg, Hanna K; Väänänen, Virpi; Järventaus, Hilkka; Suhonen, Satu; Nygren, Jonas; Hämeilä, Mervi; Valtonen, Jarkko; Heikkilä, Pirjo; Norppa, Hannu

    2008-05-31

    As the use of recycled materials and industrial by-products in asphalt mixtures is increasing, we investigated if recycled additives modify the genotoxicity of fumes emitted from asphalt. Fumes were generated in the laboratory at paving temperature from stone-mastic asphalt (SMA) and from SMA modified with waste plastic (90% polyethylene, 10% polypropylene) and tall oil pitch (SMA-WPT). In addition, fumes from SMA, SMA-WPT, asphalt concrete (AC), and AC modified with waste plastic and tall oil pitch (AC-WPT) were collected at paving sites. The genotoxicity of the fumes was studied by analysis of DNA damage (measured in the comet assay) and micronucleus formation in human bronchial epithelial BEAS 2B cells in vitro and by counting mutations in Salmonella typhimurium strains TA98 and YG1024. DNA damage was also assessed in buccal leukocytes from road pavers before and after working with SMA, SMA-WPT, AC, and AC-WPT. The chemical composition of the emissions was analysed by gas chromatography/mass spectrometry. The SMA-WPT fume generated in the laboratory induced a clear increase in DNA damage in BEAS 2B cells without metabolic activation. The laboratory-generated SMA fume increased the frequency of micronucleated BEAS 2B cells without metabolic activation. None of the asphalt fumes collected at the paving sites produced DNA damage with or without metabolic activation. Fumes from SMA and SMA-WPT from the paving sites increased micronucleus frequency without metabolic activation. None of the asphalt fumes studied showed mutagenic activity in Salmonella. No statistically significant differences in DNA damage in buccal leukocytes were detected between the pre- and post-shift samples collected from the road pavers. However, a positive correlation was found between DNA damage and the urinary metabolites of polycyclic aromatic hydrocarbons (PAHs) after work shift, which suggested an association between occupational exposures during road paving and genotoxic effects. Our

  17. Comparison of material properties of polyethylene design types and design type tests of dangerous goods packaging depending on the prestorage time with 55% nitric acid; Vergleich der Materialeigenschaften von Polyethylenformstoffen und der Baumusterpruefungen von Gefahrgutverpackungen in Abhaengigkeit von der Vorlagerungsdauer mit 55%-iger Salpetersaeure

    Energy Technology Data Exchange (ETDEWEB)

    Weltschev, Margit; Niebergall, Ute; Haufe, Manuela; Heyer, Martina

    2010-12-22

    The material parameters melt flow rate MFR, density D, notched impact strength NIS at -30 C, stress crack resistance FNCT and resistance to oxidative degradation Ox (determined by the increase of MFR) have been selected for a comparison of the polyethylene grades for one design type in the ''European standard EN 15507: 2009 - Transport packaging for dangerous goods - Comparative material testing of polyethylene grades''. The parameters have a systematic relationship with design type tests. The notched impact strength at -30 C and the resistance to oxidative degradation of the polyethylene grades determined with test specimens of compression moulded sheets are directly comparable with drop tests at -18 C of design types produced of these grades. The design types were pre-stored with the standard liquid 55 % nitric acid for 21 days at 40 C. Tests in the dissertation: a comparison of the material parameters of high-density polyethylene grades with the behaviour of design types for the transport of dangerous goods showed that the marginal drop heights of some design types increased after pre-storage with 55 % nitric acid for 21 days rather than decreased. The effects of the marginal drop heights in drop tests at -18 C, the MFR and the tensile properties tensile strength, breaking elongation and the elastic modulus of the pre-storage time with 55 % nitric acid at 40 C and 23 C were investigated to verify and extend these test results. Packaging design types (jerricans) made of three polyethylene grades from different producers were pre-stored with 55 % nitric acid for 21, 42 and 84 days at 40 C as well as for six months at 23 C. The MFR and tensile properties of jerrican cuttings as well as the marginal drop heights of the jerricans in drop tests at -18 C were determined. The values of the notched impact strength at -30 C of the polyethylene grades are not comparable with the marginal drop heights determined in drop tests at -18 C. The marginal drop

  18. Salvianolic Acid A Inhibits PDGF-BB Induced Vascular Smooth Muscle Cell Migration and Proliferation While Does Not Constrain Endothelial Cell Proliferation and Nitric Oxide Biosynthesis

    Directory of Open Access Journals (Sweden)

    Chao Huang

    2012-03-01

    Full Text Available Proliferation and migration of vascular smooth muscle cells (VSMCs are critical events in the initiation and development of restenosis upon percutaneous transluminal coronary angioplasty (PTCA. Polyphenols have been suggested to ameliorate post-angioplasty restenosis. Salvianolic A (SalA is one of the most abundant polyphenols extracted from salvia. In this study, we investigated the effect of salvianolic A (SalA on the migration and proliferation of VSMCs. We found a preferential interaction of SalA with cellular systems that rely on the PDGF signal, but not on the EGF and bFGF signal. SalA inhibits PDGF-BB induced VSMC proliferation and migration in the concentration range from 0.01 to 0.1 μM. The inhibition of SalA on VSMC proliferation is associated with cell cycle arrest. We also found that SalA inhibits the PDGFRβ-ERK1/2 signaling cascade activated by PDGF-BB in VSMCs. In addition, SalA does not influence the proliferation of endothelial cells, the synthesis of NO and eNOS protein expression. Our results suggest that SalA inhibits migration and proliferation of VSMCs induced by PDGF-BB via the inhibition of the PDGFRβ-ERK1/2 cascade, but that it does not constrain endothelial cell proliferation and nitric oxide biosynthesis. Thus, the present study suggests a novel adjunct pharmacological strategy to prevent angioplasty-related restenosis.

  19. Extraction of uranium (VI) from nitric acidwith N-decanoylpyrrolidine (DPOD) in toluene

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The extraction behaviors of uranium (VI) from nitric acid by N-decanoylpyrrolidine (DPOD) in toluene has been studied at varying concentrations of nitric acid, extractant, salting-out agent LiNO3 and at different temperatures.The mechanism of extraction is discussedin the light of the results obtained.

  20. 交联柱撑皂土催化剂上甲苯的硝酸选择性硝化%Selective Nitration of Toluene with Nitric Acid on the Cross-linked Pillared Bentonite Catalysts

    Institute of Scientific and Technical Information of China (English)

    吕春绪; 彭新华

    2001-01-01

    在交联柱撑皂土催化下,应用硝酸硝化甲苯,能提高甲苯的对位选择性硝化能力,邻对硝基甲苯比例较通常硝硫混酸方法硝化邻对位产物比例(1.67)显著降低。在所制备的NH+4、H+、La3+等系列改性铝交联柱撑皂土催化剂中,稀土La3+改性交联柱撑皂土具有较好的催化选择性和活性,邻对硝基甲苯比例达到0.75。%Para-selectivities oi toluene nitrations were enhanced by using nitric acid as nitrating agent in the presence of cross-linked pillared bentonite catalysts.Ortho-to-para ratios were greatly below 1.67 as compared with sulfonitric acid.Of a range of NH+4、H+、La3+ modified aluminium cross-linked bentonites,La3+ modiried bentonite appears to be the optimum catalytic selectivity and reactivity,up to 0.75 in a ratio of ortho and para nitrotoluene.

  1. Rheological behavior of fumed silica suspension in polyethylene glycol

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The rheological behavior of fumed silica suspensions in polyethylene glycol(PEG) was studied at steady and oscillatory shear stress using AR 2000 stress controlled rheometer. The systems show reversible shear thickening behavior and the shear-thickening behavior can be explained by the clustering mechanism. The viscosity and the degree of shear-thickening of the systems strongly depend on the mass fraction of the silica, the molecular weigh of PEG and the frequency used in the rheological measurement. The silica volume fraction of the systems is 1.16 %-3.62%, corresponding to the mass fraction of 4%- 9 %. The shear-thickening taking place in the low volume fraction may contribute to the fractal nature of the silica. At oscillatory shear stress, when the shear stress is less than the critical stress, the storage modulus decreases significantly, meanwhile the loss modulus and the complex viscosity almost remain unchanged; when the shear stress is larger than the critical stress, the storage modulus, the loss modulus and the complex viscosity increase with the increase of shear stress. The loss modulus is larger than the storage modulus in the range of stress studied and both moduli depend on frequency.

  2. Accidental exposure to isocyanate fumes in a group of firemen.

    Science.gov (United States)

    Axford, A T; McKerrow, C B; Jones, A P; Le Quesne, P M

    1976-05-01

    A total of 35 firemen involved in fighting a fire in a factory in which polyurethane foam was made were exposed to fumes of toluene di-isocyanate from two large storage tanks which were damaged during the fire, resulting in massive spillage. Most of the men experienced symptoms during the fire or during the three weeks after it. The symptoms were mainly gastrointestinal, respiratory, or neurological. Altogether 15 men described gastrointestinal symptoms which subsided within two days of onset. Respiratory symptoms were described by 31 men and were most pronounced during the three days after the fire, thereafter tending to improve. The neurological findings are described separately. When the men were reviewed at six months there was a suggestion that some of them might have sustained long-term damage to the respiratory tract, and almost four years later 20 men had persistent respiratory symptoms. Serial measurements of ventilatory capacity revealed a marked decline in the first six months although this was not sustained.

  3. Fume hood exhaust re-entry into a chemistry building.

    Science.gov (United States)

    Lamb, B K; Cronn, D R

    1986-02-01

    The rooftop air intakes are in close proximity to the fume hood exhaust vents on the roof of the attached chemistry buildings (Fulmer Hall and Fulmer Annex) at Washington State University. Complaints resulted from the apparent re-entry of hazardous and odorous exhaust vapors and gases returning into the building fresh air supplies. An atmospheric tracer study of the flow patterns and exhaust gas dilution rates determined the suitability of other potential air intake locations. Isopleth maps showed concentration patterns for tests conducted during the different wind regimes (southwest prevailing winds and substantial wintertime southeast periods). As expected, the observed dilution rates were greater than the conservative minimum dilution rates calculated from models. Tracer gas concentrations indicated large areas over which odor thresholds would exceeded for vapors resulting from typical evaporation rates of solvents. Tracer gas concentrations at the building air intakes were about the same as inside building concentrations because little dilution occurred between the intakes and building interiors. Significant infiltration was observed due to negative building pressure relative to outside. The recommendation to move the intakes down the south building walls is being followed since roof-level concentrations are typically a factor of ten or more higher than below-roof levels.

  4. Effect of fish oils containing different amounts of EPA, DHA, and antioxidants on plasma and brain fatty acids and brain nitric oxide synthase activity in rats

    OpenAIRE

    2009-01-01

    Background The interest in n-3 polyunsaturated fatty acids (PUFAs) has expanded significantly in the last few years, due to their many positive effects described. Consequently, the interest in fish oil supplementation has also increased, and many different types of fish oil supplements can be found on the market. Also, it is well known that these types of fatty acids are very easily oxidized, and that stability among supplements varies greatly. Aims of the study In this pilot study we investi...

  5. 硝酸氧化对沥青烯基有序介孔炭电化学性能的影响%The influence of nitric acid oxidation on the electrochemical performance of asphaltene-based ordered mesoporous carbon

    Institute of Scientific and Technical Information of China (English)

    王六平; 周颖; 邱介山

    2011-01-01

    采用硝酸对沥青烯基有序介孔炭(Ordered mesoporous carbon,OMC)进行氧化处理,在硝酸浓度为5mol/L、40℃~100℃下,考察了氧化温度对沥青烯基OMC的孔结构和电化学性能的影响,讨论了不同表面化学氛围的OMC孔道内电解液离子的传输过程.OMC的结构表征和性能测试采用XRD、物理吸附仪和电化学工作站等技术.结果表明:适度的硝酸氧化处理可以有效地改善OMC的电化学性能,低温氧化处理在化学改性OMC表面的同时,仍能保持其规则的孔道结构,比表面积和孔容基本不变;60℃氧化处理时,OMC表现出良好的双电层电化学行为和频率响应特性,电容器可以保持较快的充放电速率,时间常数约为6s;在5mV·s-1的扫描速率下其质量比电容值和能量密度分别为138F·g-1和3.9Wh·kg-1,较改性前分别提高了57%和63%.%Asphaltene-based ordered mesoporous carbon ( OMC) was oxidized with 5 mol/L nitric acid at 40-100 ℃ . The influence of nitric acid oxidation treatment on its textural properties and electrochemical performance as a supercapacitor electrode material was investigated and the ionic transport behavior in relation to surface chemical structure was discussed. The pore structures and electrochemical performance were examined using XRD, nitrogen adsorption and an electrochemical workstation. Results indicate that electrochemical performance can be improved with nitric acid treatment under mild conditions. The regular mesostructure can be retained, and the surface areas and pore volumes vary slightly when oxidation temperature is below 60 ℃ . A capacitor assembled with the OMC sample oxidized at 60℃ exhibits excellent electric double layer behavior, improved frequency response characteristics and a fast charge-discharge rate with a time constant of 6s. The gravimetric specific capacitance and energy density of OMC oxidized at 60 ℃ are 138 F·g-1 and 3. 9 Wh.kg-1 respectively at a scanning rate of 5 m

  6. Remedial Investigation Report on the Abandoned Nitric Acid Pipeline at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee. Energy Systems Environmental Restoration Program; Y-12 Environmental Restoration Program

    Energy Technology Data Exchange (ETDEWEB)

    1994-02-01

    Upper East Fork Poplar Creek Operable Unit 2 consists of the Abandoned Nitric Acid pipeline (ANAP). This pipeline was installed in 1951 to transport liquid wastes {approximately}4800 ft from Buildings 9212, 9215, and 9206 to the S-3 Ponds. Materials known to have been discharged through the pipeline include nitric acid, depleted and enriched uranium, various metal nitrates, salts, and lead skimmings. During the mid-1980s, sections of the pipeline were removed during various construction projects. A total of 19 locations were chosen to be investigated along the pipeline for the first phase of this Remedial Investigation. Sampling consisted of drilling down to obtain a soil sample at a depth immediately below the pipeline. Additional samples were obtained deeper in the subsurface depending upon the depth of the pipeline, the depth of the water table, and the point of auger refusal. The 19 samples collected below the pipeline were analyzed by the Oak Ridge Y-12 Plant`s laboratory for metals, nitrate/nitrite, and isotopic uranium. Samples collected from three boreholes were also analyzed for volatile organic compounds because these samples produced a response with organic vapor monitoring equipment. Uranium activities in the soil samples ranged from 0.53 to 13.0 pCi/g for {sup 238}U, from 0.075 to 0.75 pCi/g for {sup 235}U, and from 0.71 to 5.0 pCi/g for {sup 238}U. Maximum total values for lead, chromium, and nickel were 75.1 mg/kg, 56.3 mg/kg, and 53.0 mg/kg, respectively. The maximum nitrate/nitrite value detected was 32.0 mg-N/kg. One sample obtained adjacent to a sewer line contained various organic compounds, at least some of which were tentatively identified as fragrance chemicals commonly associated with soaps and cleaning solutions. The results of the baseline human health risk assessment for the ANAP contaminants of potential concern show no unacceptable risks to human health.

  7. Linoleic acid-induced expression of inducible nitric oxide synthase and cyclooxygenase II via p42/44 mitogen-activated protein kinase and nuclear factor-kappaB pathway in retinal pigment epithelial cells.

    Science.gov (United States)

    Fang, I-Mo; Yang, Chang-Hao; Yang, Chung-May; Chen, Muh-Shy

    2007-11-01

    High linoleic acid (LA) intake is known to correlate with age-related macular degeneration (AMD), but the molecular mechanisms remain unclear. This study was conducted to investigate the effects of LA on expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase II (COX-2) and their associated signaling pathways in human retinal pigment epithelial (RPE) cells. ARPE-19 cells were treated with different concentrations of LA. Expressions of iNOS and COX-2 were examined using semiquantitative reverse transcription polymerase chain reaction (RT-PCR) and Western blot analysis. Concentrations of nitric oxide (NO) and prostaglandin E(2) (PGE(2)) in the culture medium were determined by enzyme-link immunosorbent assay (ELISA). Activation of p42/44, p38, JNK mitogen-activated protein kinase (MAPK) and nuclear factors (NF)-kappaB were evaluated by Western blot analysis and electrophoretic mobility shift assay (EMSA). We found that LA induced expression of iNOS and COX-2 in RPE cells at the mRNA and protein levels in a time-and dose-dependent manner. Upregulation of iNOS and COX-2 resulted in increased production of NO and PGE(2). Moreover, LA caused degradation of IkappaB and increased NF-kappaB DNA binding activity. Effects of LA-induced iNOS and COX-2 expression were inhibited by a NF-kappaB inhibitor, pyrrolidine dithiocarbamate (PDTC). LA activated p42/44, but not p38 or JNK MAPK. Inhibition of p42/44 activity by PD98059 significantly reduced LA-induced activation of NF-kappaB. Linoleic acid-induced expression of iNOS and COX-2 as well as PGE(2) and NO release in RPE cells were sequentially mediated through activation of p42/p44, MAPK, then NF-kappaB. These results may provide new insights into both mechanisms of LA action on RPE cells and pathogenesis of age-related macular degeneration.

  8. 氮掺杂钛精矿的制备及其可见光催化活性%Preparation of nitric acid-modified titanium ore and its visible-light photocatalytic activity

    Institute of Scientific and Technical Information of China (English)

    雷雪飞; 薛向欣; 杨合

    2013-01-01

    Nitric acid-modified titanium ore (NATO) photocatalysts were prepared by the high energy ball milling method at different temperature. NATO photocatalysts were characterized by XRD, FT-IR, UV-Vis absorption spectra, TG-DTA and PL measurements. Its photocatalytic activity was checked through the photocatalytic oxidation of methyl orange as a model compound under vis light irradiation. The results showed that: mixed crystal structure was found in NATO photocatalysts; the photocatalytic activities of NATO calcined at 400℃ showed a higher catalytic activity compared to other catalysts; the higher concentration of nitrate and the visible absorption capacity,and the suitable phase ratio led to the enhancement of the photocatalytic activities of NATO calcined at 400℃ ; the decoloration rate of methyl orange reached 100% after 1h.%以硝酸作为氮源,钛精矿为原料,采用超声波复合高能球磨法,在不同煅烧温度下合成了硝酸掺杂的钛精矿催化剂(nitric acid-modified titanium ore,NATO).用X射线衍射(XRD)、傅立叶红外(FTIR)、紫外-可见漫反射光谱(UV-Vis)、差热-热重(TGDTA)和光致发光谱(PL)分析对NATO催化剂的结构和性能进行分析和表征,确定其由钛磁铁矿、钛铁矿、TiO2、钛铁氧化物等多种物相组成;在紫外-可见光区域都具有很强的光吸收能力.不同煅烧温度下,NATO催化剂的光催化活性由甲基橙的脱色率来评价,结果表明,煅烧温度为400℃时,NATO催化剂由于表面存在较高的硝酸盐含量和较高的可见光吸收能力及合适的晶相比,而具有较高的光催化活性,500W金卤灯照射1h,可将浓度为10mg/L的甲基橙废水完全降解.

  9. Profiling mild steel welding processes to reduce fume emissions and costs in the workplace.

    Science.gov (United States)

    Keane, Michael J; Siert, Arlen; Chen, Bean T; Stone, Samuel G

    2014-05-01

    To provide quantitative information to choose the best welding processes for minimizing workplace emissions, nine gas metal arc welding (GMAW) processes for mild steel were assessed for fume generation rates, normalized fume generation rates (milligram fume per gram of electrode consumed), and normalized generation rates for elemental manganese, nickel, and iron. Shielded metal arc welding (SMAW) and flux-cored arc-welding (FCAW) processes were also profiled. The fumes were collected quantitatively in an American Welding Society-type fume chamber and weighed, recovered, homogenized, and analyzed by inductively coupled atomic emission spectroscopy for total metals. The processes included GMAW with short circuit, globular transfer, axial spray, pulsed spray, Surface Tension Transfer™, Regulated Metal Deposition™, and Cold Metal Transfer™ (CMT) modes. Flux-cored welding was gas shielded, and SMAW was a single rod type. Results indicate a wide range of fume emission factors for the process variations studied. Fume emission rates per gram of electrode consumed were highest for SMAW (~13 mg fume g(-1) electrode) and lowest for GMAW processes such as pulsed spray (~1.5mg g(-1)) and CMT (~1mg g(-1)). Manganese emission rates per gram of electrode consumed ranged from 0.45 mg g(-1) (SMAW) to 0.08 mg g(-1) (CMT). Nickel emission rates were generally low and ranged from ~0.09 (GMAW short circuit) to 0.004 mg g(-1) (CMT). Iron emission rates ranged from 3.7 (spray-mode GMAW) to 0.49 mg g(-1) (CMT). The processes studied have significantly different costs, and cost factors are presented based on a case study to allow comparisons between processes in specific cost categories. Costs per linear meter of weld were $31.07 (SMAW), $12.37 (GMAW short circuit), and $10.89 (FCAW). Although no single process is the best for minimizing fume emissions and costs while satisfying the weld requirements, there are several processes that can minimize emissions. This study provides

  10. A Review for Characterization of Silica Fume and Its Effects on Concrete Properties

    Directory of Open Access Journals (Sweden)

    Mohammad Panjehpour

    2011-12-01

    Full Text Available Mineral additions which are also known as mineral admixtures have been used in Portland cement for many years. There are two types of additions which are commonly mixed into the Portland clinker or blended directly with cement these days. They are crystalline, also known as hydraulically inactive additions and pozzolanic, which are hydraulically active additions. Silica fume is very reactive pozzolan, while it is used in concrete because of its fine particles, large surface area and high SiO2 content. Silica fume is much fined separated silica obtained as a by-product in industry. It is used as an admixture in the concrete mix and it has significant effects on the properties of the resulting material. Simultaneously, silica fume can be also utilized in production of refectory and porcelain, to increase intensity and durability. In addition, it can improve the overall performance of the material as filler used in coating resin, paint, rubber and other high molecular materials. This review paper discusses the effects of silica fume on the concrete properties such as strength, modulus, ductility, permeability, chemical attack resistance, corrosion, freeze-thaw durability, creep rate. Characterisation of silica fume as well as its physical and chemical properties will also be reviewed in this paper.

  11. The detection of drugs of abuse in fingerprints using Raman spectroscopy II: cyanoacrylate-fumed fingerprints

    Science.gov (United States)

    Day, Joanna S.; Edwards, Howell G. M.; Dobrowski, Steven A.; Voice, Alison M.

    2004-07-01

    This paper describes the application of Raman spectroscopy to the detection of exogenous substances in cyanoacrylate-fumed fingerprints. The scenario considered was that of an individual handling a substance and subsequently depositing a contaminated fingerprint. These fingerprints were enhanced by cyanoacrylate fuming, a process in which a layer of white cyanoacrylate polymer is deposited on the fingerprint material, enabling visual detection. Five drugs of abuse (codeine phosphate, cocaine hydrochloride, amphetamine sulphate, barbital and nitrazepam) and five non-controlled substances of similar appearance, which may be used in the adulteration of drugs of abuse (caffeine, aspirin, paracetamol, starch and talc), were used. The substances studied could be clearly distinguished using their Raman spectra and were all successfully detected in cyanoacrylate-fumed fingerprints. Photobleaching was necessary to reduce the fluorescence background in the spectra of some substances. Raman spectra obtained from the substances in cyanoacrylate-fumed fingerprints were of a similar quality to spectra obtained from the substances under normal sampling conditions, however, interfering Raman bands arising from the cyanoacrylate polymer were present in the spectra. In most cases the only interfering band was the CN stretching mode of the polymer, and there were no cases where the interfering bands prevented identification of the substances. If necessary, the interfering bands could be successfully removed by spectral subtraction. The most difficult aspect of the detection of these substances in cyanoacrylate-fumed fingerprints was visually locating the substance in the fingerprint beneath the polymer layer in order to obtain a Raman spectrum.

  12. Effects of Exposure to Welding Fume on Lung Function: Results from the German WELDOX Study.

    Science.gov (United States)

    Lehnert, M; Hoffmeyer, F; Gawrych, K; Lotz, A; Heinze, E; Berresheim, H; Merget, R; Harth, V; Van Gelder, R; Hahn, J-U; Hartwig, A; Weiß, T; Pesch, B; Brüning, T

    2015-01-01

    The association between exposure to welding fume and chronic obstructive pulmonary disease (COPD) has been insufficiently clarified. In this study we assessed the influence of exposure to welding fume on lung function parameters. We investigated forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), FEV1/FVC, and expiratory flow rates in 219 welders. We measured current exposure to respirable particles and estimated a worker's lifetime exposure considering welding techniques, working conditions and protective measures at current and former workplaces. Multiple regression models were applied to estimate the influence of exposure to welding fume, age, and smoking on lung function. We additionally investigated the duration of working as a welder and the predominant welding technique. The findings were that age- and smoking-adjusted lung function parameters showed no decline with increasing duration, current exposure level, and lifetime exposure to welding fume. However, 15% of the welders had FEV1/FVC below the lower limit of normal, but we could not substantiate the presence of an association with the measures of exposure. Adverse effects of cigarette smoking were confirmed. In conclusion, the study did not support the notion of a possible detrimental effect of exposure to welding fume on lung function in welders.

  13. Nitric oxide promotes survival of cerebellar granule neurons cultured in vitro through the Akt pathway

    Institute of Scientific and Technical Information of China (English)

    Lin Wang; Mei Li; Lihua Zhou

    2011-01-01

    In this study, cerebellar granule neurons were used to examine the role of nitric oxide on cell survival. The N-methyl-D-aspartic acid receptor antagonist, MK-801, and the soluble guanylate cyclase antagonist, 1H-[1, 2, 4]oxadiazolo-[4, 3-a] quinoxalin-1-one, decreased cell viability, induced caspase-3, and decreased phosphorylated-Akt levels, suggesting that blockade of nitric oxide production promotes apoptosis of differentiating cerebellar granule neurons. After administration of sodium nitroprusside, an endogenous nitric oxide donor, cell viability recovered,caspase-3 expression was decreased, and phosphorylated-Akt levels increased. This study provides direct evidence that nitric oxide can sustain the survival of developing cerebellar granule neurons in vitro through the nitric oxide-Akt pathway. Moreover, endogenous nitric oxide exerts these effects in a cyclic guanosine monophosphate-dependent manner while exogenous nitric oxide does so in a cyclic guanosine monophosphate-independent manner.

  14. Manganese and welding fume exposure and control in construction.

    Science.gov (United States)

    Meeker, John D; Susi, Pam; Flynn, Michael R

    2007-12-01

    Overexposure to welding fume constituents, particularly manganese, is of concern in the construction industry due to the prevalence of welding and the scarcity of engineering controls. The control effectiveness of a commercially available portable local exhaust ventilation (LEV) unit was assessed. It consisted of a portable vacuum and a small bell-shaped hood connected by a flexible 2 inch (50.8 mm) diameter hose, in both experimental and field settings. The experimental testing was done in a semienclosed booth at a pipefitter training facility. Five paired trials of LEV control vs. no control, each approximately 1 hr in duration and conducted during two successive welds of 6 inch (152.4 mm) diameter carbon steel pipe were run in random order. Breathing zone samples were collected outside the welding hood during each trial. In the field scenario, full-shift breathing zone samples were collected from two pipefitters welding carbon steel pipe for a chiller installation on a commercial construction project. Eight days of full-shift sampling were conducted on both workers (n = 16), and the LEV was used by one of the two workers on an alternating basis for 7 of the days. All samples were collected with personal sample pumps calibrated at 2 L/min. Filter cassettes were analyzed for total particulate and manganese concentration by a certified laboratory. In the experimental setting, use of the portable LEV resulted in a 75% reduction in manganese exposure (mean 13 microg/m(3) vs. 51 microg/m(3); p 0.05). These results demonstrate that LEV use can reduce manganese exposure associated with welding tasks in construction.

  15. 42 CFR 84.1141 - Isoamyl acetate tightness test; dust, fume, and mist respirators designed for respiratory...

    Science.gov (United States)

    2010-10-01

    ... mist respirators designed for respiratory protection against fumes of various metals having an air...; Pesticide; Paint Spray; Powered Air-Purifying High Efficiency Respirators and Combination Gas Masks § 84.1141 Isoamyl acetate tightness test; dust, fume, and mist respirators designed for...

  16. Testing Silica Fume-Based Concrete Composites under Chemical and Microbiological Sulfate Attacks

    Directory of Open Access Journals (Sweden)

    Adriana Estokova

    2016-04-01

    Full Text Available Current design practices based on descriptive approaches to concrete specification may not be appropriate for the management of aggressive environments. In this study, the durability of cement-based materials with and without the addition of silica fume, subjected to conditions that leach calcium and silicon, were investigated. Chemical corrosion was simulated by employing various H2SO4 and MgSO4 solutions, and biological corrosion was simulated using Acidithiobacillus sp. bacterial inoculation, leading to disrupted and damaged surfaces; the samples’ mass changes were studied following both chemical and biological attacks. Different leaching trends were observed via X-ray fluorescence when comparing chemical with biological leaching. Lower leaching rates were found for concrete samples fortified with silica fume than those without silica fume. X-ray diffraction and scanning electron microscopy confirmed a massive sulfate precipitate formation on the concrete surface due to bacterial exposure.

  17. Properties of High Volume Fly Ash Concrete Compensated by Metakaolin or Silica Fume

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The compressive strength and dynamic modulus of high volume fly ash concrete with incorporation of either metakaolin or silica fume were investigated. The water to cementitious materials ratio was kept at 0.4 for all mixtures. The use of high volume fly ash in concrete greatly reduces the strength and dynamic modulus during the first 28 days. The decreased properties during the short term of high volume fly ash concrete is effectively compensated by the incorporation of metakaolin or silica fume. The DTA results confirmed that metakaolin or silica fume increase the amount of the hydration products. An empirical relationship between dynamic modulus and compressive strength of concrete has been obtained. This relation provides a nondestructive evaluation for estimating the strength of concrete by use of the dynamic modulus.

  18. Strength development, hydration reaction and pore structure of autoclaved slag cement with added silica fume

    Energy Technology Data Exchange (ETDEWEB)

    Xi, Y. [China Building Materials Academy, Beijing (China); Siemer, D.D. [LITCO, Idaho Falls, ID (United States); Scheetz, B.E. [Pennsylvania State Univ., University Park, PA (United States). Materials Research Lab.

    1997-01-01

    Under continuous hydrothermal treatment the strength of portland cement paste decreases with curing time and the pore structure coarsens. It was found in this study that the compressive strength of slag cement paste containing 67.5 wt.% ggbfs also decreases with time after 24 hour hydrothermal processing, but with a small addition of silica fume to the slag cement, the cement strength increases and the pore structure densifies when processed under comparable conditions. Based on observations XRD and SEM, these changes are attributed to: (1) changes in the hydration reactions and products by highly reactive silica fume, such that amorphous products dominate and the strength reducing phase {alpha}-C{sub 2}SH does not form; (2) slower hydration of slag, partially caused by the decreased pH of the pore solution, favors the formation of a dense pore structure; and (3) the space filling properties of the micro particles of silica fume.

  19. 双亚砜与TBP对铀(Ⅵ)萃取行为的比较%Comparision of extraction of U(Ⅵ) from nitric acid by disulfoxides and TBP

    Institute of Scientific and Technical Information of China (English)

    朱利明; 匡华; 崔立燕; 孙永辉; 曹正白

    2001-01-01

    研究了PhSO(CH2)nSOPh(n=2、3、4、6)-三氯甲烷体系从硝酸介质中萃取铀的行为。n=2的双亚砜在萃取时出现三相,n=3、4、6的三种双亚砜对铀的萃取规律类似于TBP,萃取性能略优于TBP。铀的溶剂化数均为1。%The extraction of dioxouranium(Ⅵ) from nitric acid solution byPhSO(CH2)nSOPh (n=2,3,4,6)-trichloromethane was studied. When the disulfoxide was PhSO(CH2)2SOPh, the third phase formed. The extraction laws of dioxouranium(Ⅵ) by the disulfoxides (n=3,4,6) were similar to that by tributyl-phosphate(TBP). Their extracting ability was slightly better than that of TBP.

  20. Sublethal concentrations of salicylic acid decrease the formation of reactive oxygen species but maintain an increased nitric oxide production in the root apex of the ethylene-insensitive never ripe tomato mutants.

    Science.gov (United States)

    Tari, Irma; Poór, Péter; Gémes, Katalin

    2011-09-01

    The pattern of salicylic acid (SA)-induced production of reactive oxygen species (ROS) and nitric oxide (NO) were different in the apex of adventitious roots in wild-type and in the ethylene-insensitive never ripe (Nr) mutants of tomato (Solanum lycopersicum L. cv Ailsa Craig). ROS were upregulated, while NO remained at the control level in apical root tissues of wildtype plants exposed to sublethal concentrations of SA. In contrast, Nr plants expressing a defective ethylene receptor displayed a reduced level of RO S and a higher NO content in the apical root cells. In wild-type plants NO production seems to be RO S(H2O2)-dependent at cell death-inducing concentrations of SA, indicating that ROS and NO may interact to trigger oxidative cell death. In the absence of significant RO S accumulation, the increased NO production caused moderate reduction in cell viability in root apex of Nr plants exposed to 10(-3) M SA. This suggests that a functional ethylene signaling pathway is necessary for the control of ROS and NO production induced by SA.

  1. Study of the reaction between {sup 51}CrO{sub 3} and concentrated nitric acid by radio chromatographic methods; Estudo da reacao entre {sup 51}CrO{sub 3} e acido nitrico concentrado por metodos radiocromatograficos

    Energy Technology Data Exchange (ETDEWEB)

    Pezzin, Sergio H. [Univesidade do Estado de Santa Catarina (UDESC), Joinville, SC (Brazil). Centro de Ciencias Tecnologicas; Collins, Carol H.; Collins, Kenneth E. [Universidade Estadual de Campinas, SP (Brazil). Inst. de Quimica

    2000-07-01

    The objective of the present work is to verify the reduction of CrO{sub 3} in concentrated nitric acid, using {sup 51}Cr as a tracer. For the study, {sup 51}CrO{sub 3} (ca. 200,000 cpm/mg) was added to 65% HNO{sub 3} and maintained under agitation at 20 deg C for specified time periods. Aliquots (100 {mu}) were analyzed by open column cation (AG50Wx8, 100-200 mesh, Na{sup +} form) chromatography, either immediately or after dilution to approximately pH 2 and storage for specified time periods. The separations, which were made by stepwise elution using HClO{sub 4} and Ca(ClO{sub 4}){sub 2} solutions as effluents with fraction collection, followed by counting with a NaI(Tl) detector and a single channel analyzer. It was verified that ca. 3.5% of Cr(III) is obtained after 15 min of reaction. The major reaction product is hexaaquo chromium(III), with minor concentrations of mononitrate penta-aquochromium(III), [Cr(H{sub 2}O){sub 5}NO{sub 3}]{sup 2+}, a product which undergoes watering at pH 2 to produce, after 360 h, [Cr(H{sub 2}O){sub 6}]{sup 3+}. (author)

  2. 从低浓度含钯硝浸液中富集钯工艺研究%Research on Concentration of Palladium from Nitric Acid Leaching Solution Containing Palladium

    Institute of Scientific and Technical Information of China (English)

    赵祝鹏; 王兴; 崔家友; 张善辉; 侯绍彬; 姜学利

    2016-01-01

    针对在银电解过程中产生的银阳极泥,研究了硝酸浸出溶解银和钯,然后采用食盐沉银、黄药富集分离钯的生产工艺。研究结果表明,银回收率在98%以上,钯富集率达到93%以上。同时,该工艺具有成本低、操作简单、贵金属回收率高等优点。%Aimed at silver anode slime produced in the course of silver electrolytic refining, Ag and Pd are dissolved by nitric acid, then Ag is subsided by salt and Pd is concentrated by butyl xanthate. The recovery rate of Ag is over 98%, the accumulation rate of Pd reaches to 93%. The process has the advantages of low cost, simple operation, high precious metals recovery.

  3. Extraction of Th(IV) from nitric acid with 40—benzoyl—2,4—dihydro—5—methyl—2—phenyl—3H—pyrazol—3—thione

    Institute of Scientific and Technical Information of China (English)

    YuShao-Ning; YangYan-Zhao; 等

    1998-01-01

    The BMPPT(4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione)was synthesized from BMPP.Its m.p.is 106-108℃,The results of the element analysis are as follows:C,68.51%,H,4.51%,N,9.26%,S.11.47%,which are in conformity with the theoretical value(C,69.15%,H,4.76%,N.9.52%,S.10.90%),The solvent extraction of Th4+ from nitric acid solution by BMPPT in benzene was studied.The extraction ability of BMPPT is not so high as that of its parent (BMPP).The Th4+ distribution ratio(DTh)in creases with the increasing pH of the aqueous phase,and pH1/2 for Th4+ was 3.2([BMPPT]=0.10mol/L),When the pH increases,the distribution ratio of Th4+ increasdes linearly with the slope of 1.59,When the concentration of BMPPT increases,the distribution ratio of Th4+ increases rapidly.The lgDTh-lg[BMPPT]is linear with the slope of 1.42 and the extraction mechanism is the cation ion-exchange.

  4. Evaluation of the relationship between PAH content and mutagenic activity of fumes from roofing and paving asphalts and coal tar pitch.

    Science.gov (United States)

    Machado, M L; Beatty, P W; Fetzer, J C; Glickman, A H; McGinnis, E L

    1993-11-01

    Fume condensates from asphalt and coal tar pitch were evaluated to determine if polycyclic aromatic hydrocarbon (PAH) composition, crude oil source, or temperature at which the fume was generated correlated with mutagenic activity. The fume condensates were tested for mutagenic activity using a modified Ames Test. Benzo[a]pyrene (BP) and other PAHs were detected in all samples. The concentration of BP in coal tar pitch was 18,100 ppm while the concentration in asphalt was less than 6 ppm. Coal tar fumes contained between two and three orders of magnitude more BP, as well as other PAH species, than asphalt fumes. Coal tar fume condensates were also approximately 100 times more mutagenic than those of asphalt. Generation temperature, crude oil source, and/or process conditions affected the PAH concentrations but not the mutagenicity in roofing asphalt fume condensates. With paving asphalt fumes, PAH content and mutagenicity varied with crude oil source but not with processing conditions; due to limited data, it was not possible to determine the effect of generation temperature. Coal tar pitch fumes generated at 316 degrees C contained significantly higher concentrations of PAHs than those generated at 232 degrees C and the mutagenic activity generally paralleled the PAH content. A subset of the paving asphalts demonstrated good correlation between mutagenicity and three- to seven-ring PAH content. These results indicate that asphalt fumes are far less mutagenic than coal tar fumes. Asphalt fumes differ in their ability to induce mutagenic activity, and, most likely, in their potential carcinogenicity.

  5. Role of Nitric Oxide and Hydrogen Sulfide in the Vasodilator Effect of Ursolic Acid and Uvaol from Black Cherry Prunus serotina Fruits.

    Science.gov (United States)

    Luna-Vázquez, Francisco J; Ibarra-Alvarado, César; Rojas-Molina, Alejandra; Romo-Mancillas, Antonio; López-Vallejo, Fabián H; Solís-Gutiérrez, Mariana; Rojas-Molina, Juana I; Rivero-Cruz, Fausto

    2016-01-12

    The present research aimed to isolate the non-polar secondary metabolites that produce the vasodilator effects induced by the dichloromethane extract of Prunus serotina (P. serotina) fruits and to determine whether the NO/cGMP and the H2S/KATP channel pathways are involved in their mechanism of action. A bioactivity-directed fractionation of the dichloromethane extract of P. serotina fruits led to the isolation of ursolic acid and uvaol as the main non-polar vasodilator compounds. These compounds showed significant relaxant effect on rat aortic rings in an endothelium- and concentration-dependent manner, which was inhibited by NG-nitro-L-arginine methyl ester (L-NAME), DL-propargylglycine (PAG) and glibenclamide (Gli). Additionally, both triterpenes increased NO and H2S production in aortic tissue. Molecular docking studies showed that ursolic acid and uvaol are able to bind to endothelial NOS and CSE with high affinity for residues that form the oligomeric interface of both enzymes. These results suggest that the vasodilator effect produced by ursolic acid and uvaol contained in P. serotina fruits, involves activation of the NO/cGMP and H2S/KATP channel pathways, possibly through direct activation of NOS and CSE.

  6. Phase analysis of fume during arc weld brazing of steel sheets with protective coatings

    Directory of Open Access Journals (Sweden)

    J. Matusiak

    2016-04-01

    Full Text Available The article presents the results of research of the phase identification and of the quantitative phase analysis of fume generated during Cold Metal Transfer (CMT, ColdArc and Metal Inert Gas / Metal Active Gas (MIG / MAG weld brazing. Investigations were conducted for hot - dip coated steel sheets with zinc (Zn and zinc-iron (Zn - Fe alloy coatings. Arc shielding gases applied during the research-related tests were Ar + O2, Ar + CO2, Ar + H2 and Ar + CO2 + H2 gas mixtures. The analysis of the results covers the influence of the chemical composition of shielding gas on the chemical composition of welding fume.

  7. A comparative study for radiological decontamination of laboratory fume hood materials.

    Science.gov (United States)

    Thomas, Elizabeth; Sweet, Lucas; MacFarlan, Paul; McNamara, Bruce; Kerschner, Harrison

    2012-08-01

    The efficacy for radiological decontamination of the laboratory standard fume hood as constructed of stainless steel, compared to that of powder-coated carbon steel is described. While the chemical inertness of powder-coated surfaces is good, faced with everyday abrasion, aggressive inorganic solutions and vapors, and penetrating organics commonly employed in government laboratory fume hoods, radiological decontamination of powder-coated steel surfaces was found to be similar to those made of stainless steel for easily solubilized or digestible radionuclides. Plutonium was difficult to remove from stainless steel and powder-coated surfaces, especially after prolonged contact times.