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1

PCE oxidation by sodium persulfate in the presence of solids.  

PubMed

Batch reactor experiments were performed to determine the effects of solids on the oxidation of tetracholoroethylene (PCE) by sodium persulfate in aqueous solution. Based on the rates of PCE degradation and chloride formation, PCE oxidation by heat-activated sodium persulfate at 50 °C in the presence of solids ranged from no detectable oxidation of PCE to the levels observed in water-only reactors. Repeated doses of sodium persulfate, undertaken to overcome the inherent solids oxidant demand, improved the rate and extent of PCE oxidation in reactors containing reference solids; however, no improvement was observed in reactors containing field soils. Additionally, no improvements in PCE oxidation were observed after pretreating Great Lakes and Appling soils with ca. 15 g/kg of sodium persulfate or 30% hydrogen peroxide to remove oxidizable fractions, or acetic acid to remove the carbonate fraction. Based on these results, in situ treatment of Great Lakes and Appling soils with heat-activated sodium persulfate is not anticipated to result in substantial PCE oxidation, while in situ treatment of Fort Lewis soils is anticipated to result in PCE oxidation. This work demonstrates the need to perform soil-specific contaminant treatability tests rather than soil oxidant demand tests when determining oxidant dosage requirements. PMID:21070044

Costanza, Jed; Otańo, Gretell; Callaghan, John; Pennell, Kurt D

2010-11-11

2

Rapid persulfate oxidation predicts PAH bioavailability in soils and sediments  

SciTech Connect

Persulfate oxidation was validated as a method to predict polycyclic aromatic hydrocarbon (PAH) bioavailability in soils and sediments. It was demonstrated for 14 field contaminated soils and sediments that residual PAH concentrations after a short (3 h) persulfate oxidation correspond well to residual PAH concentrations after 21 days of biodegradation. Persulfate oxidation of samples that had first been subjected to biodegradation yielded only limited additional PAH oxidation. This implies that oxidation and biodegradation removed approximately the same PAH fraction. Persulfate oxidation thus provides a good and rapid method for the prediction of PAH bioavailability. Thermogravimetric analysis of oxidized and untreated samples showed that persulfate oxidation primarily affected expanded organic matter. The results indicate that this expanded organic matter contained mainly readily bioavailable PAHs.

Cuypers, C.; Grotenhuis, T.; Joziasse, J.; Rulkens, W.

2000-05-15

3

Degradation of volatile organic compounds with thermally activated persulfate oxidation.  

PubMed

This study investigated the extent and treatability of the degradation of 59 volatile organic compounds (VOCs) listed in the EPA SW-846 Method 8260B with thermally activated persulfate oxidation. Data on the degradation of the 59 VOCs (in mixture) reacted with sodium persulfate in concentrations of 1 g l(-1) and 5 g l(-1) and at temperatures of 20 degrees C, 30 degrees C, and 40 degrees C were obtained. The results indicate that persulfate oxidation mechanisms are effective in degrading many VOCs including chlorinated ethenes (CEs), BTEXs and trichloroethanes that are frequently detected in the subsurface at contaminated sites. Most of the targeted VOCs were rapidly degraded under the experimental conditions while some showed persistence to the persulfate oxidation. Compounds with "CC" bonds or with benzene rings bonded to reactive functional groups were readily degraded. Saturated hydrocarbons and halogenated alkanes were much more stable and difficult to degrade. For those highly persulfate-degradable VOCs, degradation was well fitted with a pseudo first-order decay model. Activation energies of reactions of CEs and BTEXs with persulfate were determined. The degradation rates increased with increasing reaction temperature and oxidant concentration. Nevertheless, to achieve complete degradation of persulfate-degradable compounds, the systems required sufficient amounts of persulfate to sustain the degradation reaction. PMID:16202809

Huang, Kun-Chang; Zhao, Zhiqiang; Hoag, George E; Dahmani, Amine; Block, Philip A

2005-04-12

4

Defluorination of Aqueous Perfluorooctanesulfonate by Activated Persulfate Oxidation  

PubMed Central

Activated persulfate oxidation technologies based on sulfate radicals were first evaluated for defluorination of aqueous perfluorooctanesulfonate (PFOS). The influences of catalytic method, time, pH and K2S2O8 amounts on PFOS defluorination were investigated. The intermediate products during PFOS defluorination were detected by using LC/MS/MS. The results showed that the S2O82? had weak effect on the defluorination of PFOS, while the PFOS was oxidatively defluorinated by sulfate radicals in water. The defluorination efficiency of PFOS under various treatment was followed the order: HT (hydrothermal)/K2S2O8 > UV (ultraviolet)/K2S2O8 > Fe2+/K2S2O8 > US (ultrasound)/K2S2O8. Low pH was favorable for the PFOS defluorination with sulfate radicals. Increase in the amount of S2O82? had positive effect on PFOS defluorination. However, further increase in amounts of S2O82? caused insignificant improvement in PFOS defluorination due to elimination of sulfate radicals under high concentration of S2O82?. CF3(CF2)nCOOH (n?=?0–6) were detected as intermediates during PFOS defluorination. Sulfate radicals oxidation and hydrolysis were the main mechanisms involved in defluorination process of PFOS.

Yang, Shewei; Cheng, Jianhua; Sun, Jian; Hu, Yongyou; Liang, Xiaoyan

2013-01-01

5

Defluorination of aqueous perfluorooctanesulfonate by activated persulfate oxidation.  

PubMed

Activated persulfate oxidation technologies based on sulfate radicals were first evaluated for defluorination of aqueous perfluorooctanesulfonate (PFOS). The influences of catalytic method, time, pH and K2S2O8 amounts on PFOS defluorination were investigated. The intermediate products during PFOS defluorination were detected by using LC/MS/MS. The results showed that the S2O8 (2-) had weak effect on the defluorination of PFOS, while the PFOS was oxidatively defluorinated by sulfate radicals in water. The defluorination efficiency of PFOS under various treatment was followed the order: HT (hydrothermal)/K2S2O8 > UV (ultraviolet)/K2S2O8 > Fe(2+)/K2S2O8 > US (ultrasound)/K2S2O8. Low pH was favorable for the PFOS defluorination with sulfate radicals. Increase in the amount of S2O8 (2-) had positive effect on PFOS defluorination. However, further increase in amounts of S2O8 (2-) caused insignificant improvement in PFOS defluorination due to elimination of sulfate radicals under high concentration of S2O8 (2-). CF3(CF2)nCOOH (n?=?0-6) were detected as intermediates during PFOS defluorination. Sulfate radicals oxidation and hydrolysis were the main mechanisms involved in defluorination process of PFOS. PMID:24116016

Yang, Shewei; Cheng, Jianhua; Sun, Jian; Hu, Yongyou; Liang, Xiaoyan

2013-10-07

6

Persulfate oxidation of trichloroethylene with and without iron activation in porous media.  

PubMed

In situ chemical oxidation with persulfate anion (S2O82*) is a viable technique for remediation of groundwater contaminants such as trichloroethylene (TCE). An accelerated reaction using S2O82* to destroy TCE can be achieved via chemical activation with ferrous ion to generate sulfate radicals (SO4*)(E degrees =2.6 V). The column study presented here simulates persulfate oxidation of TCE in porous media (glass beads and a sandy soil). Initial experiments were conducted to investigate persulfate transport in the absence of TCE in the column. The persulfate flushing exhibited a longer residence time and revealed a moderate persulfate interaction with soils. In TCE treatment experiments, the results indicate that the water or persulfate solution would push dissolved TCE from the column. Therefore, the effluent TCE concentration gradually increased to a maximum when about one pore volume was replaced with the flushing solution in the column. The presence of Fe2+ concentration within the column caused a quick drop in effluent TCE concentration and more TCE degradation was observed. When a TCE solution was flushing through the soil column, breakthrough of TCE concentration in the effluent was relatively slow. In contrast, when the soil column was flushed with a mixed solution of persulfate and TCE, persulfate appeared to preferentially oxidize soil oxidizable matter rather than TCE during transport. Hence, persulfate oxidation of soil organics may possibly reduce the interaction between TCE and soil (e.g., adsorption) and facilitate the transport of TCE through soil columns resulting in faster breakthrough. PMID:17692892

Liang, Chenju; Lee, I-Ling; Hsu, I-Yuang; Liang, Ching-Ping; Lin, Yu-Ling

2007-08-10

7

Destruction of PCB 44 in Spiked Subsurface Soils Using Activated Persulfate Oxidation  

Microsoft Academic Search

The effectiveness of persulfate oxidation for the destruction of tetrachlorobiphenyl a representative polychlorobiphenyl (PCB),\\u000a in spiked subsurface soils was evaluated in this study. Kaolin and glacial till soils were selected as representative low\\u000a permeability soils; both soils were spiked with 50 mg PCB per dry kilogram of soil. Activation of persulfate oxidation was\\u000a necessary to achieve effective destruction of PCBs in

Yeliz Yukselen-Aksoy; Amid P. Khodadoust; Krishna R. Reddy

2010-01-01

8

Oxidative degradation of propachlor by ferrous and copper ion activated persulfate.  

PubMed

The process of in situ chemical oxidation (ISCO) by persulfate (S(2)O(8)(2-)) can be accelerated by metal ion activation, which more effectively degrades subsurface pollutants by enhancing sulfate radical (SO(4)(-)) generation. This study compared the results of propachlor degradation by Cu(2+) and Fe(2+) activated persulfate and revealed differing degradation kinetics and mechanisms between the two types of activation system. The activation of persulfate by Fe(2+) ions generally resulted in rapid degradation in the early stage, but was accompanied by a dramatic decrease in efficiency due to the rapid depletion of Fe(2+) by the sulfate radicals generated. In contrast, the Cu(2+) activated persulfate had a longer lasting degradation effect and a proportionally greater degradation enhancement at elevated Cu(2+) concentrations. An optimal Fe(2+) concentration should be sought to activate the persulfate, as a high Fe(2+) concentration of 2.5mM or above, as was used in this study, may inhibit propachlor degradation due to the competitive consumption of sulfate radicals by the excess Fe(2+) ions. Higher temperatures (55°C compared with 30°C) resulted in enhanced metal activation, particularly with the Cu(2+) activated system. Furthermore, acidic conditions were found to be more favorable for propachlor degradation by metal activated persulfate. The ecotoxicity of degraded propachlor samples, which was indicated by average well color development (AWCD) for its microbial community activity, was confirmed to be decreased during the degradation processes with these two ions activated persulfate. PMID:22226398

Liu, C S; Shih, K; Sun, C X; Wang, F

2012-01-05

9

Effect of temperature on oxidative transformation of perfluorooctanoic acid (PFOA) by persulfate activation in water  

Microsoft Academic Search

Perfluorooctanoic acid (PFOA) is an emerging environmental pollutant attracting significant attention due to its global distribution, high persistence, and bioaccumulation properties. In this study, the degradation of aqueous PFOA at different temperatures was examined using heat-activated persulfate. Using this approach, 93.5% of PFOA was degraded after 30h at 85°C with 43.6% of F? yield, and the shorter chain length compounds

C. S. Liu; C. P. Higgins; F. Wang; K. Shih

10

Persulfate Oxidation Regeneration of Granular Activated Carbon: Reversible Impacts on Sorption Behavior  

EPA Science Inventory

Chemical oxidation regeneration of granular activated carbon (GAC) is a developing technology that can be carried out utilizing thermally-activated persulfate. During chemical regeneration of GAC, aggressive oxidative conditions lead to high acidity (pH < 2) and the accumulation ...

11

Persulfate oxidation regeneration of granular activated carbon: reversible impacts on sorption behavior.  

PubMed

Chemical oxidation regeneration of granular activated carbon (GAC) is a developing technology that can be carried out utilizing thermally-activated persulfate. During chemical regeneration of GAC, aggressive oxidative conditions lead to high acidity (pH<2) and the accumulation of sodium persulfate residuals in the GAC. In this study, we investigated the impact of chemical oxidation on the sorption characteristics of methyl-tert butyl ether (MTBE) in GAC. Loss of MTBE sorption was measured in thermally-activated persulfate regenerated GAC. The accumulation of sulfur was partially responsible for the blockage of sorption sites, but sorption loss was amplified under oxidizing and acidic conditions and attributed to the formation of acidic surface oxides and enhanced electrostatic attraction and accumulation of SO(4)(2-) in GAC. Raising the pH in the GAC slurry resulted in the removal of the residual sulfate and improved MTBE sorption indicating that the mechanisms responsible for MTBE sorption loss were reversible. These results establish baseline conditions and parameters that can be used to optimize pilot- and full-scale deployment of thermally-activated persulfate regeneration of GAC. PMID:22921651

Hutson, Andy; Ko, Saebom; Huling, Scott G

2012-08-22

12

Bisphenol A treatment by the hot persulfate process: Oxidation products and acute toxicity.  

PubMed

In this study, a thermally activated persulfate oxidation process was investigated to treat aqueous Bisphenol A (BPA) solution. The effect of temperature (40-50-60-70°C), initial pH (pH=3.0, 6.5, 9.0 and 11.0) and persulfate concentration (0-20mM) on bisphenol A (BPA) and TOC removals was examined. The activation energy for hot persulfate oxidation of BPA was calculated as 184±12kJ/mol. Acidic and neutral pH values were more favorable for BPA oxidation than basic pH values. TOC removals did not exhibit a specific pattern with varying initial pHs. Gas chromatography/mass spectrometry was employed to identify oxidation products. Several aromatic and a few aliphatic compounds could be detected including benzaldehyde, p-isopropenyl phenol, 2,3-dimethyl benzoic acid, 3-hydroxy-4-methyl-benzoic acid, ethylene glycol monoformate and succinic acid. Acute toxicity tests conducted with Vibrio fischeri indicated that the inhibitory effect of 88?M BPA solution originally being 58%, increased to 84% after 30min and decreased to 22% after 90min hot persulfate treatment that could be attributed to the formation and subsequent disappearance of oxidation products. PMID:23433897

Olmez-Hanci, Tugba; Arslan-Alaton, Idil; Genc, Bora

2013-01-31

13

Persulfate oxidation for in situ remediation of TCE. I. Activated by ferrous ion with and without a persulfate-thiosulfate redox couple.  

PubMed

The objective of the laboratory study is to examine the conditions under which transition metal ions (e.g., ferrous ion, Fe2+) could activate the persulfate anion (S2O8(2)-) to produce a powerful oxidant known as the sulfate free radical (SO4-*) with a standard redox potential of 2.6 V. The SO4-* is capable of destroying groundwater contaminants in situ such as trichloroethylene (TCE). Experiments using Fe2+ as an activator under various molar ratios of S2O8(2)-/Fe2+/TCE in an aqueous system indicated that partial TCE degradation occurred almost instantaneously and then the reaction stalled. Either destruction of SO4-* in the presence of excess Fe2+ or the rapid conversion of all Fe2+ to Fe3+ limited the ultimate oxidizing capability of the system. Sequential addition of Fe2+ in small increments resulted in an increased TCE removal efficiency. Therefore, it appeared that Fe2+ played an important role in generating SO4-*. An observation of oxidation-reduction potential (ORP) variations revealed that the addition of sodium thiosulfate (Na2S2O3) to the ferrous ion activated persulfate system could significantly decrease the strong oxidizing conditions. It was hypothesized that the thiosulfate induced reducing conditions might convert Fe3+ to a lower valence state of Fe2+, making the Fe2+ available to activate persulfate decomposition. The sequential addition of thiosulfate (S2O3(2)-), after the initial stalling of ferrous ion activated persulfate oxidation of TCE, resulted in an improvement in TCE removal. The ferrous ion activated persulfate-thiosulfate redox couple resulted in fairly complete TCE degradation in aqueous systems in a short time frame. In soil slurry systems, TCE degradation was slower in comparison to aqueous systems. PMID:15081762

Liang, Chenju; Bruell, Clifford J; Marley, Michael C; Sperry, Kenneth L

2004-06-01

14

Comparative Study on Oxidative Treatments of NAPL Containing Chlorinated Ethanes and Ethenes using Hydrogen Peroxide and Persulfate in Soils  

EPA Science Inventory

The goal of this study was to assess the oxidation of NAPL in soil, 30% of which were composed of chlorinated ethanes and ethenes, using catalyzed hydrogen peroxide (CHP), activated persulfate (AP), and H2O2ā??persulfate (HP) co-amendment systems. Citrate, a buffer and iron ligand,...

15

Persulfate oxidation for in situ remediation of TCE. II. Activated by chelated ferrous ion  

Microsoft Academic Search

In situ chemical oxidation (ISCO) is a technique used to remediate contaminated soil and groundwater systems. It has been postulated that sodium persulfate (Na2S2O8) can be activated by transition metal ions such as ferrous ion (Fe2+) to produce a powerful oxidant known as the sulfate free radical (SO4?) with a redox potential of 2.6 V, which can potentially destroy organic

Chenju Liang; Clifford J Bruell; Michael C Marley; Kenneth L Sperry

2004-01-01

16

Effect of persulfate on the oxidation of benzotriazole and humic acid by e-beam irradiation.  

PubMed

These days, the use of persulfate in advanced oxidation processes (AOPs) has gained more attention as an emerging clean and efficient technology to degrade the organic pollutants. The objective of this study was to investigate the effect of the addition of persulfate on the oxidation of benzotriazole (BT) and humic acids (HAs) by irradiation. The degradation of BT (3.7 ?M) was followed under the influence of persulfate addition (200-500 ?M) in combination with a fixed radiation dose (15 Gy) in the absence and presence of HA (5 and 20mg/L) in deionized water. The main results obtained in this study on the degradation of BT in the presence of HA showed a different effect of S(2)O(8)(2-) addition during irradiation, depending on whether HA are oxidized or not-oxidized. (1) An inhibitory effect of S(2)O(8)(2-) was observed in the presence of non-oxidized HA. (2) The removal of BT was generally more important during irradiation in the presence of S(2)O(8)(2-) when HA is pre-oxidized. This could be explained by the different structures of humic acids. These differences of structures of HA were identified by physico-chemical parameters such as the absorbance in the UV (254 nm), the fluorescence and the SUVA measurement. PMID:21514992

Roshani, Babak; Leitner, Nathalie Karpel Vel

2011-03-23

17

Persulfate oxidation for in situ remediation of TCE. I. Activated by ferrous ion with and without a persulfate–thiosulfate redox couple  

Microsoft Academic Search

The objective of the laboratory study is to examine the conditions under which transition metal ions (e.g., ferrous ion, Fe2+) could activate the persulfate anion (S2O82?) to produce a powerful oxidant known as the sulfate free radical (SO4?) with a standard redox potential of 2.6 V. The SO4? is capable of destroying groundwater contaminants in situ such as trichloroethylene (TCE).

Chenju Liang; Clifford J. Bruell; Michael C. Marley; Kenneth L. Sperry

2004-01-01

18

Molecular Structure of Sodium persulfate  

NSDL National Science Digital Library

Sodium persulfate is an etchant and oxidizer. Oxidizers are highly reactive chemicals that can be used to clean or to render a metal surface free from corrosion. It is a crystalline or powdery solid at room temperature. Sodium persulfate is commonly used today as a replacement for ammonium persulfate in the etching of metal and semi-conductor surfaces.

2002-10-01

19

Strategy for identification and detection of multiple oxidative modifications within proteins applied on persulfate-oxidized hemoglobin and human serum albumin.  

PubMed

Oxidative stress has been suggested as an underlying mechanism of many human diseases. However, definitive evidence for this association has not been presented due to different shortcomings of the methods used to measure biomarkers of oxidative stress. Persulfates are oxidizing agents known to elicit hypersensitive reactions from the airways and skin. Despite a frequent use of persulfates at many work places, no biomarkers for persulfate exposure are available. The aim of this study was to develop a strategy for the identification and detection of multiple oxidative modifications within proteins. This strategy was applied on persulfate-oxidized proteins to identify oxidized peptides suitable for further investigation as biomarkers of persulfate exposure or oxidative stress. A strategy for the identification and the relative quantification of multiple oxidative modifications within proteins was developed. The usage of two software packages facilitated the search for modified peptides to a great extent. Oxidized peptides were relatively quantified using liquid chromatography/tandem mass spectrometry in selected reaction monitoring mode. The result showed that persulfates oxidize tryptophans and methionines resulting in mass shifts of 16 and/or 32 Da. Also, oxidized albumin peptides in nasal lavage fluid samples from subjects challenged with persulfate were detected. The oxidation degree before and after challenge remained constant for peptides containing methionine sulfoxide. For peptides containing oxidized tryptophan the oxidation degree increased after exposure. Some of these oxidized peptides may be suitable as biomarkers; however, further evaluation is required. PMID:21192028

Mörtstedt, Harriet; Jeppsson, Marina C; Ferrari, Giovanni; Jönsson, Bo A G; Kåredal, Monica H; Lindh, Christian H

2011-01-30

20

Bioavailability evaluation of naphthalene in soil using persulfate oxidation and ultrasonic extraction method.  

PubMed

Bioavailability is defined as the fraction of a soil contaminant readily available for microbial degradation and for naphthalene it could be estimated by conventional exhaustive extraction methods. In this study, a novel method that employed persulfate oxidation in combination with ultrasonic extraction (POUSE) was developed. Three parameters, temperature, duration of persulfate oxidation, and the ratio of persulfate to soil organic matter (2S,082 /SOM; g g-1), were investigated to obtain an optimum operating conditions. Under the condition, naphthalene bioavailability estimated by the POUSE method was verified and compared with other three exhaustive methods i.e. sonicator, supercritical fluid extraction (SFE), and soxhlet extraction (SE). When the S2,O(8)2-/SOM ratio was controlled at 11.6 g g-1, the optimum operating conditions of the POUSE method were 70 degreesC and 3 hr, for the temperature and duration. Under these conditions, the residual naphthalene concentrations were correlated well with the residual naphthalene concentrations for both the cases of freshly spiked and aged soils. By contrast, the sonicator, SFE, and the SE overestimated the naphthalene bioavailability since these three methods extracted naphthalene much more than that of biodegradation test. These results demonstrated that the POUSE could estimate more precisely the naphthalene bioavailability. PMID:22167937

Hung, Jui-Min; Liu, Hsiang-Chao; Hwu, Ching-Shyung; Chih-Hsing; Lai, Tsao Hung-Yu; Lu, Chih-Jen

2011-05-01

21

Application of magnetite-activated persulfate oxidation for the degradation of PAHs in contaminated soils.  

PubMed

In this study, feasibility of magnetite-activated persulfate oxidation (AP) was evaluated for the degradation of polycyclic aromatic hydrocarbons (PAHs) in batch slurry system. Persulfate oxidation activated with soluble Fe(II) (FP) or without activation (SP) was also tested. Kinetic oxidation of PAHs was tracked in spiked sand and in aged PAH contaminated soils at circumneutral pH. Quartz sand was spiked with: (i) single model pollutant (fluorenone) and (ii) organic extract isolated from two PAH contaminated soils (H and NM sampled from ancient coking plants) and was subjected to oxidation. Oxidation was also performed on real H and NM soils with and without an extraction pretreatment. Results indicate that oxidation of fluorenone resulted in its complete degradation by AP while abatement was very low (<20%) by SP or FP. In soil extracts spiked on sand, significant degradation of 16 PAHs was observed by AP (70-80%) in 1 week as compared to only 15% by SP or FP systems. But no PAH abatement was observed in real soils whatever the treatment used (AP, FP or SP). Then soils were subjected to an extraction pretreatment but without isolation of organic extract from soil. Oxidation of this pretreated soil showed significant abatement of PAHs by AP. On the other hand, very low degradation was achieved by FP or SP. Selective degradation of PAHs was observed by AP with lower degradation efficiency towards high molecular weight PAHs. Analyses revealed that no by-products were formed during oxidation. The results of this study demonstrate that magnetite can activate persulfate at circumneutral pH for an effective degradation of PAHs in soils. However, availability of PAHs and soil matrix were found to be the most critical factors for degradation efficiency. PMID:22273186

Usman, M; Faure, P; Ruby, C; Hanna, K

2012-01-23

22

Persulfate Oxidation of MTBE- and Chloroform-Spent Granular Activated Carbon  

EPA Science Inventory

Activated persulfate (Na2S2O8) regeneration of methyl tert-butyl ether (MTBE) and chloroform-spent GAC was evaluated in this study. Thermal-activation of persulfate was effective and resulted in greater MTBE removal than either alkaline-activation or H2O2ā??persulfate binary mixtur...

23

Mechanism of the Quenching of the Tris(bipyridine)ruthenium(II) Emission by Persulfate: Implications for Photoinduced Oxidation Reactions.  

PubMed

A revised mechanism for the oxidation of the excited state of Ru(bpy)3(2+) with the persulfate anion is described in this work. The formation of the precursor complex in the electron transfer reaction involves ion pairing between the metal complex in ground and excited states and S2O8(2-). The equilibrium constant for the ion-pair formation (KIP = 2.7 M(-1)) was determined from electrochemical measurements and analysis of thermal reaction between Ru(bpy)3(2+) and persulfate. It was found to be consistent with the calculated value estimated from the Debye-Hückel model. The analysis of rate constants for reactions between persulfate and various metal complexes indicates that thermal and photochemical reactions most likely proceed through a common pathway. Extremely high reorganization energy (ca. 3.54 eV) for the electron transfer obtained from fitting experimental data with the Marcus equation is indicative of significant nuclear reorganization during the electron transfer step. In view of these results the electron transfer can be described as dissociative probably involving substantial elongation or complete scission of the O-O bond. The proposed model accurately describes experimental results for the quenching of *Ru(bpy)3(2+) over a wide range of persulfate concentrations and resolves some discrepancies between the values of KIP and ket previously reported. The implications of various factors such as the ionic strength and dielectric constant of the medium are discussed in relation to measurements of the quantum yields in photodriven oxidation reactions employing the Ru(bpy)3(2+)/persulfate couple. PMID:24040757

Lewandowska-Andralojc, A; Polyansky, D E

2013-09-26

24

Amorphous and condensed organic matter domains: the effect of persulfate oxidation on the composition of soil\\/sediment organic matter  

Microsoft Academic Search

The composition of amorphous and condensed soil\\/sediment organic matter (SOM) domains was investigated for one soil sample and four sediment samples. These samples were oxidized with persulfate to remove amorphous SOM, before and after which the composition of SOM was studied by thermogravimetric analysis, pyrolysis-GC\\/MS, and cross polarization magic angle spinning 13C-NMR. Comparison of the SOM composition before and after

Chiel Cuypers; Tim Grotenhuis; Klaas G. J. Nierop; Elena Maneiro Franco; Adrie de Jager; Wim Rulkens

2002-01-01

25

Amorphous and condensed organic matter domains : the effects of persulfate oxidation on the composition of soil\\/sediment organic matter  

Microsoft Academic Search

The composition of amorphous and condensed soil\\/sediment organic matter (SOM) domains was investigated for one soil sample and four sediment samples. These samples were oxidized with persulfate to remove amorphous SOM, before and after which the composition of SOM was studied by thermogravimetric analysis, pyrolysis-GC\\/MS, and cross polarization magic angle spinning 13C-NMR. Comparison of the SOM composition before and after

M. P. Cuypers; J. T. C. Grotenhuis; K. G. J. Nierop; E. Maneiro Franco; Jager de A; W. H. Rulkens

2002-01-01

26

Ammonium persulfate: a safe alternative oxidizing reagent for measuring urinary iodine  

Microsoft Academic Search

The chioric acid method is most commonly used to obtain accurate and reproducible measurements of iodine and remove interfering substances. Unfortunately, chioric acid is a potential hazard, requiring an explosion-proof hood, among other precautions. We have developed a simple, convenient, and economic method for measuring urinary iodine by using 1 mol\\/L anunonium persulfate, a nonexplo- sive, nonhazardous chemical, as the

SAM PINO; SHIH-LIEH FANG; E. BRAVERMAN

27

Mechanism of persulfate activation by phenols.  

PubMed

The activation of persulfate by phenols was investigated to further the understanding of persulfate chemistry for in situ chemical oxidation (ISCO). Phenol (pKa = 10.0) activated persulfate at pH 12 but not at pH 8, suggesting activation occurred only via the phenoxide form. Evaluation of the phenoxide activation mechanism was complicated by the concurrent activation of persulfate by hydroperoxide anion, which is generated by the base catalyzed hydrolysis of persulfate. Therefore, phenoxide activation was investigated using pentachlorophenoxide at pH 8.3, midway between the pKa of pentachlorophenol (pKa = 4.8) and that of hydrogen peroxide (pKa = 11.8). Of the two possible mechanisms for phenoxide activation of persulfate (reduction or nucleophilic attack) the results were consistent with reduction of persulfate by phenoxide with oxidation of the phenoxide. The concentration of phenoxide required for maximum persulfate activation was low (1 mM). The results of this research document that phenoxides activate persulfate via reduction; phenolic moieties ubiquitous to soil organic matter in the subsurface may have a significant role in the activation of persulfate during its injection into the subsurface for ISCO. Furthermore, the results provide the foundation for activation of persulfate by other organic anions without the toxicity of phenols, such as keto acids. PMID:23663058

Ahmad, Mushtaque; Teel, Amy L; Watts, Richard J

2013-05-22

28

Evaluation of lead and COD removal from lead octoate drier effluent by chemical precipitation, coagulation–flocculation, and potassium persulfate oxidation processes  

Microsoft Academic Search

A range of treatment processes for the removal of mineral and organic pollutants from industrial wastewater have been investigated. This study was aimed to remove lead, turbidity, and chemical oxygen demand (COD) from lead octoate drier wastewater via potassium persulfate oxidation in the presence of UV and heat, chemical precipitation by sulfuric acid, and coagulation–flocculation processes. Al2(SO4)3, poly-aluminum chloride (PAC),

Anahita Rabii; Gholamreza Nabi Bidhendi; Naser Mehrdadi

2012-01-01

29

The Feasibility Study of Persulfate Oxidation to Regenerating of Spent Granular Activated Carbon  

EPA Science Inventory

Chemical oxidation is a developing technology used to regenerate contaminant-spent GAC. Chemical regeneration of GAC represents a viable option to thermal regeneration methods that are energy intensive resulting in significant consumption of fossil fuels and production of greenho...

30

Persulfate regeneration of trichloroethylene spent activated carbon.  

PubMed

The objective of this study was to demonstrate the regeneration of trichloroethylene (TCE) spent activated carbon using persulfate oxidation and iron activated persulfate (IAP) oxidation. Both processes resulted in decreases in the adsorbability of regenerated activated carbons. IAP was shown to rapidly degrade the aqueous TCE and causes a significant mineralization of the TCE. The release of chloride ions provided evidence of this. Persulfate oxidation mainly resulted in desorption of TCE from the activated carbon and only partial mineralization of the TCE through a carbon activated persulfate reaction mechanism. Concerning destruction of the TCE, in the regeneration test using persulfate, 30% of the original TCE was present in the solution and 9% remained on the activated carbon after the first regeneration cycle. In contrast, in the test that used IAP, it was observed that no TCE was present in the solution and only approximately 5% of the original TCE remained on the activated carbon after the first regeneration. Following the regeneration cycles, elemental analysis was carried out on the samples. BET surface area and EDS analysis showed some effects on the physico-chemical properties of the activated carbon such as a slight decrease in the surface area and the presence of iron precipitates on the carbon. PMID:19264399

Liang, Chenju; Lin, Ya-Ting; Shin, Wu-Hang

2009-02-12

31

Activation of persulfate by quinones: free radical reactions and implication for the degradation of PCBs.  

PubMed

There has been considerable interest in the use of persulfate for in situ chemical oxidation of organic contaminants in soils, sediments, and groundwater. Since humic acid (HA) exists ubiquitously in these environmental compartments, its redox active functional moieties, such as quinones, may play an important role in the oxidation processes of persulfate treatments. Understanding the effects of HA, especially the quinone functional groups on the degradation of pollutants by persulfate and the production of sulfate radicals (SO4(•-)) from persulfate, is beneficial for devising effective and economically feasible remediation strategies. In this study, the effects of model quinone compounds and HA on the degradation of 2,4,4'-trichlorobiphenyl (PCB28) by persulfate and the production of SO4(•-) from persulfate were investigated. It was found that quinones and HA can efficiently activate persulfate for the degradation of PCB28. The mechanism of persulfate activation was elucidated by quenching and electron paramagnetic resonance (EPR) studies. The results indicated that production of SO4(•-) from persulfate and quinones was semiquinone radical-dependent. The effects of quinone concentrations were also studied. The findings of this study elucidated a new pathway of persulfate activation, which could degrade environmental contaminants efficiently and provide useful information for the remediation of contaminated soil and water by persulfate. PMID:23586773

Fang, Guodong; Gao, Juan; Dionysiou, Dionysios D; Liu, Cun; Zhou, Dongmei

2013-04-26

32

INVESTIGATION OF CHLORINATED METHANES TREATABILITY USING ACTIVATED SODIUM PERSULFATE  

Microsoft Academic Search

In situ chemical oxidation is a frequently used remedial approach for the destruction of chlorinated ethenes such as tetrachloroethene (PCE) and trichloroethene (TCE). However, treatment of more recalcitrant chloroethanes and chloromethanes have challenged traditional oxidation reagents. Recently, new methods of sodium persulfate reagent activation have been developed and these systems have shown promise for improved treatment performance. The new methods

Duane K. Root; Ellen M. Lay; Philip A. Block; William G. Cutler

2005-01-01

33

Fenton- and Persulfate-driven Regeneration of Contaminant-spent Granular Activated Carbon  

EPA Science Inventory

Fenton- or persulfate-driven chemical oxidation regeneration of spent granular activated carbon (GAC) involves the combined, synergistic use of two treatment technologies: adsorption of organic chemicals onto GAC and chemical oxidation regeneration of the spent-GAC. Environmental...

34

Interaction of polyquaternary ammonium salt and persulfate  

Microsoft Academic Search

An interaction between poly(diallyldimethylammonium chloride) and ammonium persulfate in aqueous solutions has been detected and studied by methods of turbidimetry and viscometry. Investigations were carried out with the cationic polymer of different molecular weight. It was shown that association between low-molecular-weight polyquaternary ammonium salt polycations and persulfate anions was predominant over the chemical (redox) reaction with counterions Cl –. Appreciably

Edita Mazoniene; RimaJule Zemaitaitiene; Gintaras Buika; Algirdas Zemaitaitis

2004-01-01

35

Final report on the safety assessment of Ammonium, Potassium, and Sodium Persulfate.  

PubMed

Ammonium, Potassium, and Sodium Persulfate are inorganic salts used as oxidizing agents in hair bleaches and hair-coloring preparations. Persulfates are contained in hair lighteners at concentrations up to 60%, in bleaches and lighteners at up to 22% and 16%, respectively, and in off-the-scalp products used to highlight hair strands at up to 25%. They are used in professional product bleaches and lighteners at similar concentrations. Much of the available safety test data are for Ammonium Persulfate, but these data are considered applicable to the other salts as well. Acute dermal, oral, and inhalation toxicity studies are available, but only the latter are remarkable, with gross lesions observed in the lungs, liver, stomach, and spleen. In short-term and subchronic feeding studies the results were mixed; some studies found no evidence of toxicity and others found local damage to the mucous membrane in the gastrointestinal tract, but no other systemic effects. Short-term inhalation toxicity was observed when rats were exposed to aerosolized Ammonium Persulfate at concentrations of 4 mg/m3 and greater. Ammonium Persulfate (as a moistened powder) was not an irritant to intact rabbit skin, but was sensitizing (in a saline solution) to the guinea pig. It was slightly irritating to rabbit eyes. Ammonium Persulfate was negative in the Ames test and the chromosomal aberration test. No significant evidence of tumor promotion or carcinogenicity was observed in studies of rats receiving topical applications of Ammonium Persulfate. The persulfates were reported to cause both delayed-type and immediate skin reactions, including irritant dermatitis, allergic eczematous dermatitis, localized contact urticaria, generalized urticaria, rhinitis, asthma, and syncope. The most common causes of allergic dermatitis in hairdressers are the active ingredients in hair dyes, and Ammonium Persulfate has been identified as a frequent allergen. A sensitization study that also examined the incidence of urticarial reactions was performed with 17.5% Ammonium, Potassium, and Sodium Persulfate under occlusive patches. At this concentration and exposure conditions, a mixture of these Persulfates was not sensitizing, and application of Ammonium, Potassium, and Sodium Persulfate did not result in an urticarial reaction. In normal use (i.e., not occluded and rinsed off), it was expected that a concentration greater than 17.5% would also be safe. Given the clinical reports of urticarial reactions, however, manufacturers and formulators should be aware of the potential for urticarial reactions at concentrations of Persulfates greater than 17.5%. Based on the available data, the Cosmetic Ingredient Review (CIR) Expert Panel concluded that Ammonium, Potassium, and Sodium Persulfate are safe as used as oxidizing agents in hair colorants and lighteners designed for brief discontinuous use followed by thorough rinsing from the hair and skin. PMID:11766134

Pang, S; Fiume, M Z

2001-01-01

36

Microwave-Assisted COD Removal from Landfill Leachate by Hydrogen Peroxide, Peroxymonosulfate and Persulfate  

Microsoft Academic Search

H2O2-based advanced oxidation processes (AOPs) and SO4·--based AOPs were proved novel and promising techniques in treatment of wasterwater. Microwave (MW)-assisted hydrogen peroxide (H2O2), peroxymonosulfate (PMS) and persulfate (PS) were used to dispose of COD in landfill leachate. Oxidant dosage and chloride concentration were investigated as the major operating conditions. The initial COD is 4062.8 mg\\/L. It is demonstrated that MW-assisted

Wenyi Zhang; Shiying Yang; Rui Niu; Xueting Shao; Liang Shan; Xin Yang; Ping Wang

2010-01-01

37

Developing slow-release persulfate candles to treat BTEX contaminated groundwater.  

PubMed

The development of slow-release chemical oxidants for sub-surface remediation is a relatively new technology. Our objective was to develop slow-release persulfate-paraffin candles to treat BTEX-contaminated groundwater. Laboratory-scale candles were prepared by heating and mixing Na(2)S(2)O(8) with paraffin in a 2.25 to 1 ratio (w/w), and then pouring the heated mixture into circular molds that were 2.38 cm long and either 0.71 or 1.27 cm in diameter. Activator candles were prepared with FeSO(4) or zerovalent iron (ZVI) and wax. By treating benzoic acid and BTEX compounds with slow-release persulfate and ZVI candles, we observed rapid transformation of all contaminants. By using (14)C-labeled benzoic acid and benzene, we also confirmed mineralization (conversion to CO2) upon exposure to the candles. As the candles aged and were repeatedly exposed to fresh solutions, contaminant transformation rates slowed and removal rates became more linear (zero-order); this change in transformation kinetics mimicked the observed dissolution rates of the candles. By stacking persulfate and ZVI candles on top of each other in a saturated sand tank (14×14×2.5 cm) and spatially sampling around the candles with time, the dissolution patterns of the candles and zone of influence were determined. Results showed that as the candles dissolved and persulfate and iron diffused out into the sand matrix, benzoic acid or benzene concentrations (C(o)=1 mM) decreased by >90% within 7 d. These results support the use of slow-release persulfate and ZVI candles as a means of treating BTEX compounds in contaminated groundwater. PMID:22776257

Kambhu, Ann; Comfort, Steve; Chokejaroenrat, Chanat; Sakulthaew, Chainarong

2012-07-07

38

Decolorization of anthraquinone dye Reactive Blue 19 by the combination of persulfate and zero-valent iron.  

PubMed

Decolorization of anthraquinone dye Reactive Blue 19 (RB19) with sulfate radicals generated in situ from persulfate and zero-valent iron (ZVI) was investigated. The effects of initial solution pH, initial concentration of RB19, ZVI and persulfate, reaction temperature and common dissolved anions were studied. 100% color removal efficiency and 54% TOC removal efficiency were achieved in 45 min with an initial RB19 concentration of 0.1 mM under typical conditions (pH 7.0, 0.8 g L(-1) ZVI, 10 mM persulfate and 30 C). The decolorization efficiency of RB19 increased with higher iron dosage, higher initial persulfate concentration, and higher reaction temperature. It is also an acid driven process. The decolorization process followed pseudo-first order kinetics and the activation energy was 98.1 kJ mol-1. RB19 decolorization was inhibited by common dissolved anions such as CL-, NO3-, H2PO4- and HCO3- since they reacted with sulfate radicals that retarded the oxidation process. The experiment demonstrated that the combination of persulfate and ZVI was a promising technology for the decolorization of dye wastewater. PMID:22097057

Le, Chen; Wu, Jin-Hua; Li, Ping; Wang, Xiangde; Zhu, Neng-Wu; Wu, Ping-Xiao; Yang, Bo

2011-01-01

39

Decolorization of an azo dye Orange G in microbial fuel cells using Fe(II)-EDTA catalyzed persulfate.  

PubMed

This study constructed a microbial fuel cell (MFC) using Fe(II)-EDTA catalyzed persulfate as the cathode solutions to decolorize Orange G (OG) and harvest electricity simultaneously. Chelated Fe(2+) could activate persulfate to generate sulfate free radicals (SO(4)(-)) which with high oxidation potential (E(0)=2.6 V) can degrade azo dyes. The influence of some important factors such as pH value of cathode solutions, dosages of K(2)S(2)O(8), Fe(2+) and EDTA were investigated in a two-chamber microbial fuel cell. Under an optimal condition, the maximum power density achieved 91.1 mW m(-2), the OG removal rate was 97.4% and the K(2)S(2)O(8) remaining rate was 47.3% after 12 h. The OG degradation by Fe(II)-EDTA catalyzed persulfate was found to follow the second-order kinetic model. PMID:23073095

Niu, Cheng-Gang; Wang, Ying; Zhang, Xue-Gang; Zeng, Guang-Ming; Huang, Da-Wei; Ruan, Min; Li, Xiang-Wei

2012-09-08

40

Competition by aquifer materials in a bimetallic nanoparticle/persulfate system for the treatment of trichloroethylene.  

PubMed

It has been suggested in the literature that aquifer materials can compete with the target organic compounds in an activated peroxygen system. In this study, we employed a rapid treatment method using persulfate activated with bimetallic nanoparticles to investigate the competition between aquifer materials and the dissolved phase of a target organic compound. The concentration of dissolved trichloroethylene (TCE) remaining after using the activated persulfate system was two- to three-fold higher in a soil slurry batch system than in an aqueous batch system. For all five aquifer materials investigated, an increase in the mass of the aquifer solids significantly decreased the degradation of TCE. A linear relationship was observed between the mass of aquifer materials and the initial TCE degradation rate, suggesting that the organic carbon and/or aquifer material constituents (e.g., carbonates and bicarbonates) compete with the oxidation of TCE. PMID:23949733

Al-Shamsi, Mohammed Ahmad; Thomson, Neil R

2013-09-25

41

Removal of 1,1,1-trichloroethane from aqueous solution by a sono-activated persulfate process.  

PubMed

1,1,1-Trichloroethane (TCA), labeled as a priority pollutant by the Environmental Protection Agency (EPA) of China, can be removed from groundwater by sonochemical oxidation. The sonochemical oxidation of TCA in the presence of persulfate (PS) showed a significant synergistic effect. The operational parameters, ultrasonic frequency, PS/TCA molar ratio, radical scavenger, inorganic anions (Cl(-), CO(3)(2-), HCO(3)(-) and NO(3)(-)) and humic acid (HA), were evaluated during the investigation of the sonochemical reaction. The results showed that the degradation of TCA followed pseudo-first-order kinetics, and the rate constant was found to increase with increasing ultrasonic frequency but to decrease with both an increasing PS/TCA molar ratio and an increasing concentration of inorganic anions. With a concentration of 4.46mg/L of HA in solution, an enhanced effect was observed. Further addition of HA retarded the degradation rate of TCA. TCA could be eliminated almost completely by sono-activated persulfate oxidation, with sulfate and hydroxyl radicals serving as the principal oxidants as confirmed by the addition of radical scavengers. Eleven chlorinated degradation intermediates were detected and quantified by purge and trap gas chromatography coupled with mass spectrometry (P&T-GC-MS) in the absence of pH buffer. Three TCA degradation pathways were therefore proposed. In conclusion, the sono-activated persulfate oxidation process appears to be a highly promising technique for the remediation of TCA-contaminated groundwater. PMID:23266439

Li, Bingzhi; Li, Lin; Lin, Kuangfei; Zhang, Wei; Lu, Shuguang; Luo, Qishi

2012-12-03

42

Preparation of Mg-vermiculite nanoparticles using potassium persulfate treatment.  

PubMed

Delamination/exfoliation process of the Mg-vermiculite (Letovice, Czech Republic), particles with size less than 5 microm, was studied after potassium persulfate treatment and compared with known method utilized hydrogen peroxide treatment. X-ray powder diffraction (XRPD) patterns showed that treatment of Mg-vermiculite with different molar concentration of potassium persulfate: c = 0.02, 0.04, and 0.08 mol x dm(-3) at the temperature 60 degrees C for 2 hr caused reduction of relative intensity (I(rel.)) of the basal 001 diffraction to the 15%, 9%, and 4%, respectively, compared to intensity of 001 diffraction of untreated Mg-vermiculite (I(rel.) = 100%). On the other hand I(rel.) of the 001 diffraction of Mg-vermiculite after treatment with 30% and 50% (c = 9.8 and 17.4 mol x dm(-3)) hydrogen peroxide at the 60 degrees C for 2 hr decreased only to I(rel.) = 36% and 32%, respectively. Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) verified effect of potassium persulfate treatment on structure degradation which is connected with higher degree of delamination/exfoliation of the particles and their cracking into nano-sized particles. PMID:17037860

Mat?jka, Vlastimil; Supovį-Krķstkovį, Monika; Kratosvį, Gabriela; Valįskovį, Marta

2006-08-01

43

Promoted degradation of perfluorooctanic acid by persulfate when adding activated carbon.  

PubMed

Treatment of persistent perfluorooctanoic acid (PFOA) in water using persulfate (PS) oxidation typically requires an elevated temperature or UV irradiation, which is energy-consuming. Under relatively low temperatures of 25-45°C, activated carbon (AC) activated PS oxidation of PFOA was evaluated for its potential of practical applications. With presence of AC in PS oxidation, PFOA removal efficiency at 25°C reached 682% with a high defluorination efficiency of 549% after 12h and few intermediates of short-chain perfluorinated carboxylic acids (PFCAs) were found. The removal and defluorination rates with the combined AC/PS system were approximately 12 and 19 times higher than those of the PS-only system, respectively. Activated carbon not only removes PFOA through adsorption, but also activates PS to form sulfate radicals that accelerate the decomposition and mineralization of PFOA. The activation energy for PS oxidation of PFOA was reduced from 668 to 261kJ/mol by the catalytic effect of AC, which implies a lower reaction temperature and a shorter reaction time would suffice. A 2-cycle schematic reaction mechanism was used to describe PS oxidation of PFOA with the generation of various intermediates and end-products. PMID:23978721

Lee, Yu-Chi; Lo, Shang-Lien; Kuo, Jeff; Huang, Chin-Pao

2013-08-08

44

Disinfection of ballast water with iron activated persulfate.  

PubMed

The treatment of ballast water carried onboard ships is critical to reduce the spread of nonindigenous aquatic organisms that potentially include noxious and harmful taxa. We tested the efficacy of persulfate (peroxydisulfate, S2O8(2-), PS) activated with zerovalent iron (Fe(0)) as a chemical biocide against two taxa of marine phytoplankton grown in bench-scale, batch cultures: the diatom, Pseudonitzshia delicatissima and the green alga, Dunaliella tertiolecta . After testing a range of PS concentrations (0-4 mM activated PS) and exposure times (1-7 days), we determined that a dosage of 4 mM of activated PS was required to inactivate cells from both species, as indicated by reduced or halted growth and a reduction in photosynthetic performance. Longer exposure times were required to fully inactivate D. tertiolecta (7 days) compared to P. delicatissima (5 days). Under these conditions, no recovery was observed upon placing cells from the exposed cultures into fresh media lacking biocide. The results demonstrate that activated PS is an effective chemical biocide against species of marine phytoplankton. The lack of harmful byproducts produced during application makes PS an attractive alternative to other biocides currently in use for ballast water treatments and merits further testing at a larger scale. PMID:24024829

Ahn, Samyoung; Peterson, Tawnya D; Righter, Jason; Miles, Danielle M; Tratnyek, Paul G

2013-09-25

45

Tight Gas Sands Research Program: Field Operations and Analysis. Degradation of Hydroxypropyl Guar Fracturing Fluids by Enzyme, Oxidative, and Catalyzed Oxidative Breakers. Part 1. Linear Hydroxypropyl Guar Solutions. Topical Report, February 1991-December 1991.  

National Technical Information Service (NTIS)

The research was designed to accomplish the following objectives: Determine the effects of pH, temperature, and polymer concentration on HPG solution degradation by enzyme, oxidative (ammonium persulfate), and catalyzed oxidative breakers (ammonium persul...

D. Craig S. A. Holditch

1993-01-01

46

78 FR 52969 - Persulfates From China; Scheduling of a Full Five-Year Review Concerning the Antidumping Duty...  

Federal Register 2010, 2011, 2012, 2013

...Third Review)] Persulfates From China; Scheduling of a Full Five-Year Review Concerning...Commission hereby gives notice of the scheduling of a full review pursuant to section...the merchandise is sold at the retail level, representative consumer...

2013-08-27

47

Laser flash photolysis of sodium persulfate in aqueous solution with additions of dimethylformamide  

Microsoft Academic Search

The method of laser flash photolysis with excitation at 308nm was used to study the photochemistry of persulfate-ion in aqueous solutions with additions of N,N-dimethylformamide (DMF). The photolysis of S2O82? in water gives rise to SO4? radical anions with a 0.55 quantum yield. The rate constant of SO4? recombination was measured (2k=(2.7±0.2)×109M?1s?1 at ionic strength ?=0.9M). In the presence of

K. L Ivanov; E. M Glebov; V. F Plyusnin; Yu. V Ivanov; V. P Grivin; N. M Bazhin

2000-01-01

48

78 FR 40695 - Persulfates From the People's Republic of China: Final Results of Expedited Third Sunset Review...  

Federal Register 2010, 2011, 2012, 2013

On March 1, 2013, the Department of Commerce (``the Department'') initiated a sunset review of the antidumping duty order on persulfates from the People's Republic of China (``PRC''). On the basis of a notice of intent to participate, and an adequate substantive response filed on behalf of domestic interested parties, as well as a lack of response from any respondent interested parties, the......

2013-07-08

49

Oxidation of Aromatic Aldehydes Using Oxone  

ERIC Educational Resources Information Center

|The experiment demonstrating the feasibility of using water as a solvent for organic reactions which highlights the cost and environmental benefits of its use is presented. The experiment encourages students to think in terms of the reaction mechanism of the oxidation of aldehydes knowing that potassium persulfate is the active oxidant in Oxone…

Gandhari, Rajani; Maddukuri, Padma P.; Thottumkara, Vinod K.

2007-01-01

50

Chemical modification of chitin by grafting with polystyrene using ammonium persulfate initiator.  

PubMed

Chitin was successfully grafted with polystyrene by free radical mechanism using ammonium persulfate (APS) initiator. The reaction was carried out in aqueous medium. The effect of pH, chitin:monomer weight ratio, APS, reaction time and reaction temperature were investigated. The results showed that the optimum conditions for grafting of polystyrene were found as follows: pH 7, chitin:monomer weight ratio of 1:3, 0.4g of APS, reaction temperature of 60°C and reaction time 2h. The graft copolymer was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA) and differential scanning electron microscopy (DSC). Gel permeation chromatography (GPC) analysis carried out on the hydrolyzed graft copolymer showed that the Mn and Mw were 6.3395×10(4)g/mol and 1.69283×10(5)g/mol, respectively, with polydispersity index of 2.7. PMID:24053848

Abu Naim, Ahmedy; Umar, Abdulganiyu; Sanagi, Mohd Marsin; Basaruddin, Noraimi

2013-07-31

51

Heat-activated cooling devices: A guidebook for general audiences  

SciTech Connect

Heat-activated cooling is refrigeration or air conditioning driven by heat instead of electricity. A mill or processing facility can us its waste fuel to air condition its offices or plant; using waste fuel in this way can save money. The four basic types of heat-activated cooling systems available today are absorption cycle, desiccant system, steam jet ejector, and steam turbine drive. Each is discussed, along with cool storage and biomass boilers. Steps in determining the feasibility of heat-activated cooling are discussed, as are biomass conversion, system cost and integration, permits, and contractor selection. Case studies are given.

Wiltsee, G.

1994-02-01

52

78 FR 35314 - Persulfates From China; Notice of Commission Determination To Conduct a Full Five-Year Review  

Federal Register 2010, 2011, 2012, 2013

The Commission hereby gives notice that it will proceed with a full review pursuant to section 751(c)(5) of the Tariff Act of 1930 (19 U.S.C. 1675(c)(5)) to determine whether revocation of the antidumping duty order on persulfates from China would be likely to lead to continuation or recurrence of material injury within a reasonably foreseeable time. A schedule for the review will be established......

2013-06-12

53

A new catalyst for n-butane isomerization: persulfate-modified Al 2O 3–ZrO 2  

Microsoft Academic Search

The n-butane isomerization reaction on Al-promoted zirconia catalysts modified by persulfate was studied both at low temperature in the absence of hydrogen and at high temperature in the presence of hydrogen. The addition of Al shows a significant enhancement in the activity and stability of the samples for n-butane isomerization at 250°C. After running on stream for 200h, the n-butane

Yongde Xia; Weiming Hua; Zi Gao

1999-01-01

54

On the efficiency of methylene blue versus persulfate catalysis of polyacrylamide gels, as investigated by capillary zone electrophoresis.  

PubMed

The efficiency of a novel method of photopolymerization, based on photoinitiating the reaction with methylene blue (MB), in presence of a redox couple (sodium toluenesulfinate and diphenyliodonium chloride), vs, the conventional persulfate--N,N,N',N'-tetramethylethylenediamine redox couple was investigated as a function of different effectors in solution. Oxygen dissolved in the gelling mixture strongly quenches persulfate catalysis, while leaving essentially unaltered the process initiated by photopolymerization. On the contrary, the presence of 8 M urea substantially accelerates a persulfate-driven reaction, boosting the conversion of monomers to near completion (> 98%) while leaving the photopolymerization process largely unaffected. Polyacrylamide polymerization has also been performed in a number of hydroorganic solvents (all in a 50:50 v/v ratio): dimethyl sulfoxide (DMSO), tetramethylurea, formamide and dimethylformamide. In all cases, the persulfate-catalyzed reaction was strongly quenched and even completely inhibited (in DMSO), whereas the photopolymerization process was essentially unaffected by any of these organic solvents. The reaction kinetics of the methylene blue-driven reaction could not be ameliorated when admixing an anionic dye (e.g., eosin Y) to the cationic MB, even when amply changing their molar ratios. Thus, it appears that photocatalysis with MB (and the redox couple sodium toluene-sulfinate and diphenyliodonium chloride) is a unique process, proceeding at optimum rate under the most adverse conditions, completely insensitive to any kind of positive and negative effectors and able to ensure at least 95% monomer conversion under the standard conditions of 1 h reaction time at room temperature.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8125068

Caglio, S; Righetti, P G

1993-10-01

55

Plutonium oxide dissolution  

SciTech Connect

Several processing options for dissolving plutonium oxide (PuO[sub 2]) from high-fired materials have been studied. The scoping studies performed on these options were focused on PuO[sub 2] typically generated by burning plutonium metal and PuO[sub 2] produced during incineration of alpha contaminated waste. At least two processing options remain applicable for dissolving high-fired PuO[sub 2] in canyon dissolvers. The options involve solid solution formation of PuO[sub 2] With uranium oxide (UO[sub 2]) and alloying incinerator ash with aluminum. An oxidative dissolution process involving nitric acid solutions containing a strong oxidizing agent, such as cerium (IV), was neither proven nor rejected. This uncertainty was due to difficulty in regenerating cerium (IV) ions during dissolution. However, recent work on silver-catalyzed dissolution of PuO[sub 2] with persulfate has demonstrated that persulfate ions regenerate silver (II). Use of persulfate to regenerate cerium (IV) or bismuth (V) ions during dissolution of PuO[sub 2] materials may warrant further study.

Gray, J.H.

1992-09-30

56

Performance of a Stirling engine powered heat activated heat pump  

Microsoft Academic Search

The paper updates the status of the development program for a heat activated heat pump (HAHP) which employs a natural gas fired Stirling engine to drive a Rankine cycle vapor compressor. The HAHP has the potential for reducing the amount of gas required for space heating. Particular emphasis is placed on a description of the hardware comprising the HAHP and

W. D. C. Richards; W. L. Auxer

1978-01-01

57

[Influences of pH and complexing agents on degradation of reactive brilliant blue KN-R by ferrous activated persulfate].  

PubMed

The influences of pH and complexing agents on degradation of reactive brilliant blue KN-R by ferrous activated persulfate were investigated, and finally the complexed and the uncomplexed system were compared. Because the lower the pH the more quickly will be the dissociation of S2O8(2-) to the SO4(-*) and the ORP of the dominant radical SO4(-*) in the acidic condition is higher than the dominant radical *OH in the alkaline condition, KN-R degradation rates in acidic condition are far outweigh in the neutral and alkaline conditions. When pH value was 3, the residual rate of KN-R was 17.0% within 3 hours by EDTA system with the lowest PS consumption rate 32.3%, so EDTA was the best complexing agent choice in acidic condition. When pH value was 7, the residual rates of KN-R were 11.3%, 12.4% within 3 days by EDTA, citric acid system with the PS residual rates 28.9%, 28.0% respectively, so EDTA, citric acid were the better choices in the neutral condition. When pH value was 10, glucose acid, citric acid, EDTA and tartaric acid systems all had the similar KN-R degradation rates and PS residual rates, so all could acted as the complexing agents, when the system contained trace amounts of ferrous, the addition of complexing agent would greatly improve the degradation rate of pollutant, from original 52.5% to 79.3% of 3 d, so PS is suitable for in situ chemical oxidation (ISCO). PMID:22624381

Zhang, Cheng; Wan, Jin-Quan; Ma, Yong-Wen; Wang, Yan; Huang, Ming-Zhi; Lan, Ming

2012-03-01

58

Potential for chlorate interference in ion chromatographic determination of total nitrogen in natural waters following alkaline persulfate digestion.  

PubMed

Determination of total nitrogen in aqueous samples after thermal potassium peroxydisulfate (persulfate) digestion is a commonly used alternative to the tedious Kjeldahl procedure. When ion chromatography is used to quantify the nitrate formed during digestion, there is a potential for interference from a chlorate peak if the digested sample initially contained chloride in concentrations close to or greater than the concentration of nitrogen. It was determined that this interference can be avoided either by using chromatographic conditions which cleanly resolve the nitrate and chlorate peaks (e.g., the Dionex AG9-HG column) or by using digestion reagent concentrations chosen to maintain a high pH throughout the digestion. The second alternative is not a viable option for investigators using a single digestion for both total nitrogen (TN) and total phosphorus (TP) analysis. PMID:10536854

Halstead, J A; Edwards, J; Soracco, R J; Armstrong, R W

1999-10-01

59

Wet-oxidation and automated colorimetry for simultaneous determination of organic carbon, nitrogen and phosphorus dissolved in seawater  

Microsoft Academic Search

We developed a simple and reliable method which allows simultaneous determination of organic forms of carbon (DOC), nitrogen (DON) and phosphorus (DOP) dissolved in seawater. Conversion of dissolved organic matter (DOM) to inorganic products (carbon dioxide, nitrate+nitrite and soluble reactive phosphate) is performed by a persulfate wet-oxidation in low alkaline condition. After oxidation, the concentration of the inorganic products dissolved

Patrick Raimbault; Wilfried Pouvesle; Frédéric Diaz; Nicole Garcia; Richard Sempéré

1999-01-01

60

A study on microwave oxidation of landfill leachate--contributions of microwave-specific effects.  

PubMed

Microwave oxidation process (MOP) was evaluated for treatment of landfill leachate. The experimental parameters include pH, temperature, oxidant doses, microwave power setting, and irradiation time. The study explored the microwave-specific effects of the MOP. The contributions of pure thermal, persulfate oxidation and microwave irradiation on TOC removal were quantified. It was then found the combinations of them were usually synergistic in MOP except two of them were antagonistic (128 W/85°C/1M Na(2)S(2)O(8) and 128 W/85°C/2M Na(2)S(2)O(8)). At the highest temperature tested (85°C) in this study, microwave irradiation may cause generation and termination of oxidizing radicals at adverse rates. The study also found that persulfate decayed rapidly in either MOP or conventional heating oxidation (CHO) treatment of landfill leachate. PMID:23287411

Chou, Yu-Chieh; Lo, Shang-Lien; Kuo, Jeff; Yeh, Chih-Jung

2012-12-03

61

Novel High-Viscosity Polyacrylamidated Chitosan for Neural Tissue Engineering: Fabrication of Anisotropic Neurodurable Scaffold via Molecular Disposition of Persulfate-Mediated Polymer Slicing and Complexation  

PubMed Central

Macroporous polyacrylamide-grafted-chitosan scaffolds for neural tissue engineering were fabricated with varied synthetic and viscosity profiles. A novel approach and mechanism was utilized for polyacrylamide grafting onto chitosan using potassium persulfate (KPS) mediated degradation of both polymers under a thermally controlled environment. Commercially available high molecular mass polyacrylamide was used instead of the acrylamide monomer for graft copolymerization. This grafting strategy yielded an enhanced grafting efficiency (GE = 92%), grafting ratio (GR = 263%), intrinsic viscosity (IV = 5.231 dL/g) and viscometric average molecular mass (MW = 1.63 × 106 Da) compared with known acrylamide that has a GE = 83%, GR = 178%, IV = 3.901 dL/g and MW = 1.22 × 106 Da. Image processing analysis of SEM images of the newly grafted neurodurable scaffold was undertaken based on the polymer-pore threshold. Attenuated Total Reflectance-FTIR spectral analyses in conjugation with DSC were used for the characterization and comparison of the newly grafted copolymers. Static Lattice Atomistic Simulations were employed to investigate and elucidate the copolymeric assembly and reaction mechanism by exploring the spatial disposition of chitosan and polyacrylamide with respect to the reactional profile of potassium persulfate. Interestingly, potassium persulfate, a peroxide, was found to play a dual role initially degrading the polymers—“polymer slicing”—thereby initiating the formation of free radicals and subsequently leading to synthesis of the high molecular mass polyacrylamide-grafted-chitosan (PAAm-g-CHT)—“polymer complexation”. Furthermore, the applicability of the uniquely grafted scaffold for neural tissue engineering was evaluated via PC12 neuronal cell seeding. The novel PAAm-g-CHT exhibited superior neurocompatibility in terms of cell infiltration owing to the anisotropic porous architecture, high molecular mass mediated robustness, superior hydrophilicity as well as surface charge due to the acrylic chains. Additionally, these results suggested that the porous PAAm-g-CHT scaffold may act as a potential neural cell carrier.

Kumar, Pradeep; Choonara, Yahya E.; du Toit, Lisa C.; Modi, Girish; Naidoo, Dinesh; Pillay, Viness

2012-01-01

62

Degradation of Corn Oil Wastes by Fenton Reaction and Under Mildly Basic Media in the Presence of Oxidants Assisted with Sun Light  

Microsoft Academic Search

The degradation of water soluble corn oil wastes was carried out by Fenton reaction and also under mildly basic media in the presence of oxidants, such as hydrogen peroxide and persulfate, assisted with solar light. The degradation efficiency was obtained by analysis of chemical oxygen demand, carbon dioxide and gas chromatography. Over 90% of both chemical oxygen demand abatement and

Josefina Vergara Sįnchez; Susana Silva Martķnez; Maria del Refugio Trejo Hernįndez

63

Methods of Analysis by the U.S. Geological Survey National Water Quality Laboratory: Evaluation of Alkaline Persulfate Digestion as an Alternative to Kjeldahl Digestion for Determination of Total and Dissolved Nitrogen and Phosphorus in Water.  

National Technical Information Service (NTIS)

This report describes USGS methods I-2650-03 and I-4650-03 for determining total nitrogen and total phosphorus in filtered and whole-water alkaline persulfate digests, respectively. All aspects of the methods are described, including sample preparation an...

C. J. Patton J. R. Kryskalla

2003-01-01

64

Oxidative Alkaline leaching of Americium from simulated high-level nuclear waste sludges  

SciTech Connect

Oxidative alkaline leaching has been proposed to pre-treat the high-level nuclear waste sludges to remove some of the problematic (e.g., Cr) and/or non-radioactive (e.g., Na, Al) constituents before vitrification. It is critical to understand the behavior of actinides, americium and plutonium in particular, in oxidative alkaline leaching. We have studied the leaching behavior of americium from four different sludge simulants (BiPO{sub 4}, BiPO{sub 4 modified}, Redox, PUREX) using potassium permanganate and potassium persulfate in alkaline solutions. Up to 60% of americium sorbed onto the simulants is leached from the sludges by alkaline persulfate and permanganate. The percentage of americium leached increases with [NaOH] (between 1.0 and 5.0 M). The initial rate of americium leaching by potassium persulfate increases in the order BiPO{sub 4} sludge < Redox sludge < PUREX sludge. The data are most consistent with oxidation of Am{sup 3+} in the sludge to either AmO{sub 2}{sup +} or AmO{sub 2}{sup 2+} in solution. Though neither of these species is expected to exhibit long-term stability in solution, the potential for mobilization of americium from sludge samples would have to be accommodated in the design of any oxidative leaching process for real sludge samples.

Reed, Wendy A.; Garnov, Alexander Yu.; Rao, Linfeng; Nash, Kenneth L.; Bond, Andrew H.

2004-01-23

65

Evaluation of activated carbon for remediating benzene contamination: adsorption and oxidative regeneration.  

PubMed

This study investigated the potential usage of activated carbon (AC) as a permeable reactive barrier material for the adsorption of benzene contaminant. Sodium persulfate (SPS) or pyrite (FeS(2)) activated SPS oxidation was used for the regeneration of spent AC. Results indicate that persulfate oxidation of AC caused a loss of electrons and a reduction in adsorptive capacity due to the formation of acidic functional groups on the AC. Concerning the reactants that can be used for oxidation of the benzene contaminants, SPS/FeS(2)/AC, as oppose to SPS/AC, can achieve benzene destruction in both the aqueous and the sorbed phases. Furthermore, regeneration of benzene spent AC by SPS or SPS/FeS(2) revealed that SPS oxidation resulted primarily in desorption of benzene over direct oxidation of AC sorbed benzene. In contrast, the SPS/FeS(2) system achieved complete oxidation of desorbed benzene in the aqueous phase while also oxidizing sorbed benzene. Results of re-adsorption show that oxidative regeneration recovered around 70% of the AC adsorption sites and the remaining capacity was mostly occupied by the residual benzene on the AC. This study demonstrates that SPS or FeS(2) activated SPS oxidation is an effective alternative method for the regeneration of spent AC. PMID:20621415

Liang, Chenju; Chen, Yan-Jyun

2010-06-23

66

Heat-activated heat-pump development and potential application of Stirling-engine technology  

SciTech Connect

Presented is a brief overview of the heat-activated heat pump technology development program being carried out with emphasis on the Stirling engine technology projects. The major projects are reviewed as they were formulated and carried out under the previous product development guidelines. The revised technology development focus and current status of those major hardware projects are discussed. The key issues involved in applying Stirling engine technology to heat pump equipment are assessed. The approach and planned future activities to address those issues are described. Also included are brief descriptions of two projects in this area supported by the Gas Research Institute (GRI).

Fairchild, P.D.; West, C.D.

1982-01-01

67

Heat-activated heat-pump development and potential application of Stirling-engine technology  

NASA Astrophysics Data System (ADS)

Presented is a brief overview of the heat-activated heat pump technology development program being carried out with emphasis on the Stirling engine technology projects. The major projects are reviewed as they were formulated and carried out under the previous product development guidelines. The revised technology development focus and current status of those major hardware projects are discussed. The key issues involved in applying Stirling engine technology to heat pump equipment are assessed. The approach and planned future activities to address those issues are described. Also included are brief descriptions of two projects in this area supported by the Gas Research Institute.

Fairchild, P. D.; West, C. D.

1982-06-01

68

A molecular light-driven water oxidation catalyst.  

PubMed

Two mononuclear Ru(II) complexes, [Ru(ttbt)(pynap)(I)]I and [Ru(tpy)(Mepy)(2)(I)]I (tpy = 2,2';6,2"-terpyridine; ttbt = 4,4',4"-tri-tert-butyltpy; pynap = 2-(pyrid-2'-yl)-1,8-naphthyridine; and Mepy = 4-methylpyridine), are effective catalysts for the oxidation of water. This oxidation can be driven by a blue (?(max) = 472 nm) LED light source using [Ru(bpy)(3)]Cl(2) (bpy = 2,2'-bipyridine) as the photosensitizer. Sodium persulfate acts as a sacrificial electron acceptor to oxidize the photosensitizer that in turn drives the catalysis. The presence of all four components, light, photosensitizer, sodium persulfate, and catalyst, are required for water oxidation. A dyad assembly has been prepared using a pyrazine-based linker to join a photosensitizer and catalyst moiety. Irradiation of this intramolecular system with blue light produces oxygen with a higher turnover number than the analogous intermolecular component system under the same conditions. PMID:22698450

Kaveevivitchai, Nattawut; Chitta, Raghu; Zong, Ruifa; El Ojaimi, Maya; Thummel, Randolph P

2012-06-20

69

Selective disruption of high sensitivity heat activation but not capsaicin activation of TRPV1 channels by pore turret mutations.  

PubMed

The capsaicin receptor transient receptor potential vanilloid (TRPV)1 is a highly heat-sensitive ion channel. Although chemical activation and heat activation of TRPV1 elicit similar pungent, painful sensation, the molecular mechanism underlying synergistic activation remains mysterious. In particular, where the temperature sensor is located and whether heat and capsaicin share a common activation pathway are debated. To address these fundamental issues, we searched for channel mutations that selectively affected one form of activation. We found that deletion of the first 10 amino acids of the pore turret significantly reduced the heat response amplitude and shifted the heat activation threshold, whereas capsaicin activation remained unchanged. Removing larger portions of the turret disrupted channel function. Introducing an artificial sequence to replace the deleted region restored sensitive capsaicin activation in these nonfunctional channels. The heat activation, however, remained significantly impaired, with the current exhibiting diminishing heat sensitivity to a level indistinguishable from that of a voltage-gated potassium channel, Kv7.4. Our results demonstrate that heat and capsaicin activation of TRPV1 are structurally and mechanistically distinct processes, and the pore turret is an indispensible channel structure involved in the heat activation process but is not part of the capsaicin activation pathway. Synergistic effect of heat and capsaicin on TRPV1 activation may originate from convergence of the two pathways on a common activation gate. PMID:22412190

Cui, Yuanyuan; Yang, Fan; Cao, Xu; Yarov-Yarovoy, Vladimir; Wang, KeWei; Zheng, Jie

2012-03-12

70

Selective disruption of high sensitivity heat activation but not capsaicin activation of TRPV1 channels by pore turret mutations  

PubMed Central

The capsaicin receptor transient receptor potential vanilloid (TRPV)1 is a highly heat-sensitive ion channel. Although chemical activation and heat activation of TRPV1 elicit similar pungent, painful sensation, the molecular mechanism underlying synergistic activation remains mysterious. In particular, where the temperature sensor is located and whether heat and capsaicin share a common activation pathway are debated. To address these fundamental issues, we searched for channel mutations that selectively affected one form of activation. We found that deletion of the first 10 amino acids of the pore turret significantly reduced the heat response amplitude and shifted the heat activation threshold, whereas capsaicin activation remained unchanged. Removing larger portions of the turret disrupted channel function. Introducing an artificial sequence to replace the deleted region restored sensitive capsaicin activation in these nonfunctional channels. The heat activation, however, remained significantly impaired, with the current exhibiting diminishing heat sensitivity to a level indistinguishable from that of a voltage-gated potassium channel, Kv7.4. Our results demonstrate that heat and capsaicin activation of TRPV1 are structurally and mechanistically distinct processes, and the pore turret is an indispensible channel structure involved in the heat activation process but is not part of the capsaicin activation pathway. Synergistic effect of heat and capsaicin on TRPV1 activation may originate from convergence of the two pathways on a common activation gate.

Cui, Yuanyuan; Yang, Fan; Cao, Xu; Yarov-Yarovoy, Vladimir

2012-01-01

71

Longitudinal effects of age on heat-activated sweat gland density and output in healthy active older men  

Microsoft Academic Search

To investigate longitudinal effects of age on heat-activated sweat gland density and output, eight healthy active men (mean age 65–70 years) were retested after 5-years using 60-min passive heating [by placing the lower legs and feet in a 42°C water bath while sitting in a warm chamber (35°C and 45% relative humidity)]. Their height, body mass, surface area-to-mass ratio, mean

Yoshimitsu Inoue

1996-01-01

72

Microwave-assisted chemical oxidation of biological waste sludge: Simultaneous micropollutant degradation and sludge solubilization.  

PubMed

Microwave-assisted hydrogen peroxide (MW/H2O2) treatment and microwave-assisted persulfate (MW/S2O8(2-)) treatment of biological waste sludge were compared in terms of simultaneous antibiotic degradation and sludge solubilization. A 2(3) full factorial design was utilized to evaluate the influences of temperature, oxidant dose, and holding time on the efficiency of these processes. Although both MW/H2O2 and MW/S2O8(2-) yielded ?97% antibiotic degradation with 1.2g H2O2 and 0.87g S2O8(2-) per gram total solids, respectively, at 160°C in 15min, MW/S2O8(2-) was found to be more promising for efficient sludge treatment at a lower temperature and a lower oxidant dosage, as it allows more effective activation of persulfate to produce the SO4(-) radical. Relative to MW/H2O2, MW/S2O8(2-) gives 48% more overall metal solubilization, twofold higher improvement in dewaterability, and the oxidation of solubilized ammonia to nitrate in a shorter treatment period. PMID:23928124

Bilgin Oncu, Nalan; Akmehmet Balcioglu, Isil

2013-07-19

73

Oxidative Activation of Bacillus cereus Spores  

PubMed Central

A study was made of the activation of Bacillus cereus strain T spores by using the oxidizing agent sodium perborate. The degree of activation was measured with constant germination conditions by using L-alanine, inosine, adenosine, and L-alanine plus adenosine as germination stimulants. The germinal response following the various treatments was compared with the responses obtained with heat activation. It was concluded that the optimal time for activation with 30 mM sodium perborate at room temperature was about 4 hr. If the exposure time was greatly extended, the spores would germinate spontaneously. When the perborate treatment followed heat activation, the germinal response to L-alanine was stimulated, to inosine retarded and without apparent effect for adenosine or L-alanine plus adenosine. Results of experiments designed to demonstrate deactivation by slow oxidation showed that spores activated with sodium perborate were not deactivated by slow oxidation, whereas those activated by heat were. A deactivation study using mercaptoethanol as the deactivation agent showed that both methods of activation could be deactivated after a 24-hr exposure, but this deactivation was reversible by extending the exposure to mercaptoethanol. The results of heat-sensitivity studies revealed that about 70% of the sodium perborate-activated spores were heat sensitive after 60 min in a germination menstruum of L-alanine plus adenosine, whereas similarly treated heat-activated and nonactivated spores were about 99.99% heat sensitive, respectively.

Cochran, Stuart A.; Ordal, Z. John

1973-01-01

74

Graphene-assisted room-temperature synthesis of 2D nanostructured hybrid electrode materials: dramatic acceleration of the formation rate of 2D metal oxide nanoplates induced by reduced graphene oxide nanosheets.  

PubMed

A new prompt room temperature synthetic route to 2D nanostructured metal oxide-graphene-hybrid electrode materials can be developed by the application of colloidal reduced graphene oxide (RGO) nanosheets as an efficient reaction accelerator for the synthesis of ?-MnO2 2D nanoplates. Whereas the synthesis of the 2D nanostructured ?-MnO2 at room temperature requires treating divalent manganese compounds with persulfate ions for at least 24 h, the addition of RGO nanosheet causes a dramatic shortening of synthesis time to 1 h, underscoring its effectiveness for the promotion of the formation of 2D nanostructured metal oxide. To the best of our knowledge, this is the first example of the accelerated synthesis of 2D nanostructured hybrid material induced by the RGO nanosheets. The observed acceleration of nanoplate formation upon the addition of RGO nanosheets is attributable to the enhancement of the oxidizing power of persulfate ions, the increase of the solubility of precursor MnCO3, and the promoted crystal growth of ?-MnO2 2D nanoplates. The resulting hybridization between RGO nanosheets and ?-MnO2 nanoplates is quite powerful not only in increasing the surface area of manganese oxide nanoplate but also in enhancing its electrochemical activity. Of prime importance is that the present ?-MnO2 -RGO nanocomposites show much superior electrode performance over most of 2D nanostructured manganate systems including a similar porous assembly of RGO and layered MnO2 nanosheets. This result underscores that the present RGO-assisted solution-based synthesis can provide a prompt and scalable method to produce nanostructured hybrid electrode materials. PMID:23559338

Sung, Da-Young; Gunjakar, Jayavant L; Kim, Tae Woo; Kim, In Young; Lee, Yu Ri; Hwang, Seong-Ju

2013-04-04

75

Treatment of aqueous wastes contaminated with Congo Red dye by electrochemical oxidation and ozonation processes.  

PubMed

Synthetic aqueous wastes polluted with Congo Red (CR) have been treated by two advanced oxidation processes: electrochemical oxidation on boron doped diamond anodes (BDD-EO) and ozonation under alkaline conditions. For same concentrations, galvanostatic electrolyses have led to total COD and TOC removals but ozonation process can reach only 85% and 81% of COD and TOC removals, respectively. UV-vis qualitative analyses have shown different behaviors of CR molecules towards ozonation and electrochemical oxidation. Rapid discoloration has been observed during ozonation, whereas color persistence till the end of galvanostatic electrolyses has been seen during BDD-EO process. It seems that the oxidation mechanisms involved in the two processes are different: simultaneous destruction of azoic groups is suggested during ozonation process but consecutive destruction of these groups is proposed during BDD-EO. However, energetic study has evidenced that BDD-EO appears more efficient and more economic than ozonation in terms of TOC removals. These results have been explained by the fact that during BDD-EO, other strong oxidants electrogenerated from the electrolyte oxidation such as persulfates and direct-oxidation of CR and its byproducts on BDD anodes complement the hydroxyl radicals mediated oxidation to accomplish the total mineralization of organics. PMID:19394762

Faouzi Elahmadi, Mohammed; Bensalah, Nasr; Gadri, Abdellatif

2009-03-11

76

Temporal stability of solid oxidizers at high temperature and humidity. Memorandum report  

SciTech Connect

Chemical Warfare/Biological Warfare (CW/BW) decontamination operations may rely on aqueous solutions prepared from stored solid oxidizers. Needed are data defining the shipboard storage stability of candidate oxidizers. Therefore, the stability of a series of potential decontaminants has been examined at high temperature (90 + C) and humidity (95 + % R.H.). The loss of oxidizing capacity in aliquots of the oxidizers was followed with time by iodometric titration. Calcium hypochlorite lost over 99% of its oxidizing capacity in less than two days, whereas lithium hypochlorite retained one-third oxidizing capacity for approximately twenty days. Sodium perborate, and sodium persulfate were very hygroscopic and unstable with time. H-48 decomposed in approximately two days, while sodium isocyanurate lost about 80% of its oxidizing capacity in two weeks. The data presented documents severe stability problems of one sort or another with all the materials tested, although overall the sodium isocyanurate appeared to be the more stable candidate undr extreme conditions. In any case, packaging and storage considerations are shown to be important for any potential decontaminant to be stored under environmentally severe conditions.

Pellenbarg, R.E.; Dotson, D.A.

1985-09-30

77

In-situ Spectroscopy of Water Oxidation at Ir Oxide Nanocluster Drivenby Visible TiOCr Charge-Transfer Chromophore in Mesoporous Silica  

SciTech Connect

An all-inorganic photocatalytic unit consisting of a binuclear TiOCr charge-transfer chromophore coupled to an Ir oxide nanocluster has been assembled on the pore surface of mesoporous silica AlMCM-41. In situ FT-Raman and EPR spectroscopy of an aqueous suspension of the resulting IrxOy-TiCr-AlMCM-41 powder reveal the formation of superoxide species when exciting the Ti(IV)OCr(III) --> Ti(III)OCr(IV) metal-to-metal charge-transfer chromophore with visible light. Use of H218O confirms that the superoxide species originates from oxidation of water. Photolysis in the absence of persulfate acceptor leads to accumulation of Ti(III) instead. The results are explained by photocatalytic oxidation of water at Ir oxide nanoclusters followed by trapping of the evolving O2 by transient Ti(III) centers to yield superoxide. Given the flexibility to select donor metals with appropriate redox potential, photocatalytic units consisting of a binuclear charge-transfer chromophore coupled to a water oxidation catalyst shown here constitute a step towards thermodynamically efficient visible light water oxidation units.

Frei, Heinz; Han, Hongxian; Frei, Heinz

2008-06-03

78

The Chimeric Approach Reveals That Differences in the TRPV1 Pore Domain Determine Species-specific Sensitivity to Block of Heat Activation*  

PubMed Central

The capsaicin-, heat-, and proton-activated ion channel TRPV1, a member of the transient receptor potential cation channel family is a polymodal nociceptor. For almost a decade, TRPV1 has been explored by the pharmaceutical industry as a potential target for example for pain conditions. Antagonists which block TRPV1 activation by capsaicin, heat, and protons were developed by a number of pharmaceutical companies. The unexpected finding of hyperthermia as an on-target side effect in clinical studies using polymodal TRPV1 antagonists has prompted companies to search for ways to circumvent hyperthermia, for example by the development of modality-selective antagonists. The significant lack of consistency of the pharmacology of many TRPV1 antagonists across different species has been a further obstacle. JYL-1421 for example was shown to block capsaicin and heat responses in human and monkey TRPV1 while it was largely ineffective in blocking heat responses in rat TRPV1. These findings suggested structural dissimilarities between different TRPV1 species relevant for small compound antagonism for example of heat activation. Using a chimeric approach (human and rat TRPV1) in combination with a novel FLIPR-based heat activation assay and patch-clamp electrophysiology we have identified the pore region as being strongly linked to the observed species differences. We demonstrate that by exchanging the pore domains JYL-1421, which is modality-selective in rat can be made modality-selective in human TRPV1 and vice-versa.

Papakosta, Marianthi; Dalle, Carine; Haythornthwaite, Alison; Cao, Lishuang; Stevens, Edward B.; Burgess, Gillian; Russell, Rachel; Cox, Peter J.; Phillips, Stephen C.; Grimm, Christian

2011-01-01

79

The Effect of Al2O3 Addition on the Thermal Diffusivity of Heat Activated Acrylic Resin  

PubMed Central

Aim: This study aimed at investigating the effect of adding 5% to 20% by weight aluminium oxide powder (Al2O3) on thermal diffusivity of heat–polymerized acrylic resin. Material and Methods: Twenty five cylindrical test specimens with an embedded thermocouple were used to determine thermal diffusivity over a physiologic temperature range (0 to 70°C). The specimens were divided into five groups (5 specimens/group) which were coded A to E. Group A was the control group (unmodified acrylic resin specimens). The specimens of the remaining four groups were reinforced with 5%, 10%, 15%, and 20% Al2O3 by weight. Results were analysed by using one–way analysis of variance (ANOVA). Results: Test specimens which belonged to Group E showed the highest mean thermal diffusivity value of 10.7mm2/sec, followed by D (9.09mm2/sec), C (8.49mm2/sec), B(8.28mm2/sec) and A(6.48mm2/sec) groups respectively. Thermal diffusivities of the reinforced acrylic resins were found to be significantly higher than that of the unmodified acrylic resin. Thermal diffusivity was found to increase in proportion to the weight percentage of alumina filler. Conclusion: Al2O3 fillers have potential to provide increased thermal diffusivity. Increasing the heat transfer characteristics of the acrylic resin base material could lead to more patient satisfaction.

Atla, Jyothi; Manne, Prakash; Gopinadh, A.; Sampath, Anche; Muvva, Suresh Babu; Kishore, Krishna; Sandeep, Chiramana; Chittamsetty, Harika

2013-01-01

80

The Effect of Al2O3 Addition on the Thermal Diffusivity of Heat Activated Acrylic Resin.  

PubMed

Aim: This study aimed at investigating the effect of adding 5% to 20% by weight aluminium oxide powder (Al2O3) on thermal diffusivity of heat-polymerized acrylic resin. Material and Methods: Twenty five cylindrical test specimens with an embedded thermocouple were used to determine thermal diffusivity over a physiologic temperature range (0 to 70°C). The specimens were divided into five groups (5 specimens/group) which were coded A to E. Group A was the control group (unmodified acrylic resin specimens). The specimens of the remaining four groups were reinforced with 5%, 10%, 15%, and 20% Al2O3 by weight. Results were analysed by using one-way analysis of variance (ANOVA). Results: Test specimens which belonged to Group E showed the highest mean thermal diffusivity value of 10.7mm(2)/sec, followed by D (9.09mm(2)/sec), C (8.49mm(2)/sec), B(8.28mm(2)/sec) and A(6.48mm(2)/sec) groups respectively. Thermal diffusivities of the reinforced acrylic resins were found to be significantly higher than that of the unmodified acrylic resin. Thermal diffusivity was found to increase in proportion to the weight percentage of alumina filler. Conclusion: Al2O3 fillers have potential to provide increased thermal diffusivity. Increasing the heat transfer characteristics of the acrylic resin base material could lead to more patient satisfaction. PMID:24086917

Atla, Jyothi; Manne, Prakash; Gopinadh, A; Sampath, Anche; Muvva, Suresh Babu; Kishore, Krishna; Sandeep, Chiramana; Chittamsetty, Harika

2013-08-01

81

Treatment of hydrocarbon contamination under flow through conditions by using magnetite catalyzed chemical oxidation.  

PubMed

Soil pollution by hydrocarbons (aromatic and aliphatic hydrocarbons) is a major environmental issue. Various treatments have been used to remove them from contaminated soils. In our previous studies, the ability of magnetite has been successfully explored to catalyze chemical oxidation for hydrocarbon remediation in batch slurry system. In the present laboratory study, column experiments were performed to evaluate the efficiency of magnetite catalyzed Fenton-like (FL) and activated persulfate (AP) oxidation for hydrocarbon degradation. Flow-through column experiments are intended to provide a better representation of field conditions. Organic extracts isolated from three different soils (an oil-contaminated soil from petrochemical industrial site and two soils polluted by polycyclic aromatic hydrocarbon (PAH) originating from coking plant sites) were spiked on sand. After solvent evaporation, spiked sand was packed in column and was subjected to oxidation using magnetite as catalyst. Oxidant solution was injected at a flow rate of 0.1 mL min(-1) under water-saturated conditions. Organic analyses were performed by GC-mass spectrometry, GC-flame ionization detector, and micro-Fourier transform infrared spectroscopy. Significant abatement of both types of hydrocarbons (60-70 %) was achieved after chemical oxidation (FL and AP) of organic extracts. No significant by-products were formed during oxidation experiment, underscoring the complete degradation of hydrocarbons. No selective degradation was observed for FL with almost similar efficiency towards all hydrocarbons. However, AP showed less reactivity towards higher molecular weight PAHs and aromatic oxygenated compounds. Results of this study demonstrated that magnetite-catalyzed chemical oxidation can effectively degrade both aromatic and aliphatic hydrocarbons (enhanced available contaminants) under flow-through conditions. PMID:22684901

Usman, M; Faure, P; Lorgeoux, C; Ruby, C; Hanna, K

2012-06-09

82

Oxidative conversion as a means of detecting precursors to perfluoroalkyl acids in urban runoff.  

PubMed

A new method was developed to quantify concentrations of difficult-to-measure and unidentified precursors of perfluoroalkyl carboxylic (PFCA) and sulfonic (PFSA) acids in urban runoff. Samples were exposed to hydroxyl radicals generated by thermolysis of persulfate under basic pH conditions and perfluoroalkyl acid (PFAA) precursors were transformed to PFCAs of related perfluorinated chain length. By comparing PFCA concentrations before and after oxidation, the concentrations of total PFAA precursors were inferred. Analysis of 33 urban runoff samples collected from locations around the San Francisco Bay, CA indicated that PFOS (2.6-26 ng/L), PFOA (2.1-16 ng/L), and PFHxA (0.9-9.7 ng/L) were the predominant perfluorinated compounds detected prior to sample treatment. Following oxidative treatment, the total concentrations of PFCAs with 5-12 membered perfluoroalkyl chains increased by a median of 69%, or between 2.8 and 56 ng/L. Precursors that produced PFHxA and PFPeA upon oxidation were more prevalent in runoff samples than those that produced PFOA, despite lower concentrations of their corresponding perfluorinated acids prior to oxidation. Direct measurements of several common precursors to PFOS and PFOA (e.g., perfluorooctanesulfonamide and 8:2 fluorotelomer sulfonate) accounted for less than 25% of the observed increase in PFOA, which increased by a median value of 37%. Exposure of urban runoff to sunlight, advanced oxidation processes, or microbes could result in modest, but measurable, increases in concentrations of PFCAs and PFSAs. PMID:22900587

Houtz, Erika F; Sedlak, David L

2012-08-17

83

Oxides (GCMP)  

NSDL National Science Digital Library

Oxides: this is a resource in the collection "General Chemistry Multimedia Problems". In this problem we will explore the properties of the oxides of a few elements. We will add samples of the oxides to universal indicator solution and learn about the acid-base character of the oxides. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.

84

Feasibility study on an oxidant-injected permeable reactive barrier to treat BTEX contamination: adsorptive and catalytic characteristics of waste-reclaimed adsorbent.  

PubMed

The adsorptive and catalytic characteristics of waste-reclaimed adsorbent (WR), which is a calcined mixture of bottom-ash and dredged-soil, was investigated for its application to treating BTEX contamination. BTEX adsorption in WR was 54%, 64%, 62%, and 65%, respectively, for a 72 h reaction time. Moreover, the catalytic characteristics of WR were observed when three types of oxidation systems (i.e., H(2)O(2), persulfate (PS), and H(2)O(2)/Fe(III)/oxalate) were tested, and these catalytic roles of WR could be due to iron oxide on its surface. In PS/WR system, large amounts of metal ions from WR were released because of large drops of solution pH, and the surface area of WR was also greatly reduced. Moreover, the BTEX that was removed per consumed oxidant (?C(rem)/?Ox) increased with increasing PS. In H(2)O(2)/Fe(III)/oxalate with WR system, the highest BTEX degradation rate constants (k(deg)) were calculated as 0.338, 0.365, 0.500 and 0.716 h(-1), respectively, when 500 mM of H(2)O(2) was used, and the sorbed BTEX on the surface of WR was also degraded, which suggests the regeneration of WR. Therefore, the oxidant-injected permeable reactive barrier filled in WR could be an alternative to treating BTEX with both adsorption and catalytic degradation. PMID:21514045

Do, Si-Hyun; Kwon, Yong-Jae; Kong, Sung-Ho

2011-04-08

85

Liquid chromatography, chemical oxidation, and online carbon isotope dilution mass spectrometry as a universal quantification system for nonvolatile organic compounds.  

PubMed

A procedure for the universal detection and quantification of polar organic compounds separated by liquid chromatography (LC) based on postcolumn carbon isotope dilution mass spectrometry (IDMS) was developed. The eluent from the LC column is mixed online with a continuous flow of (13)C-enriched sodium bicarbonate, and the sodium persulfate oxidation reaction in acidic media is employed to achieve isotope equilibration. All carbon-containing compounds eluting from the column are oxidized to (12)CO(2) and (13)CO(2), respectively, and the carbon dioxide is separated from the aqueous phase using a gas-permeable membrane. The gaseous carbon dioxide is then carried to the mass spectrometer for isotope ratio measurements. Different water-soluble organic compounds were evaluated using a flow injection configuration to assess the efficiency of the oxidation process. Most water-soluble organic compounds tested showed quantitative oxidation. However, chemical structures involving conjugated C?N double bounds and guanidinium-like structures were found to be resistant to the oxidation and were further studied. For this purpose, (13)C(1)-labeled creatine (with the isotopic label in the guanidinium group) was employed as model compound. Specific conditions for the quantitative oxidation of these compounds required lower flow rates and the addition of metallic catalysts. This novel approach was tested as a universal detection and quantification system for LC. A simple standard mixture of four amino acids was separated under 100% aqueous conditions and quantified without the need for specific standards with good accuracy and precision using potassium hydrogen phthalate as internal standard. The main field of application of the developed method is for the purity assessment of organic standards with direct traceability to the International System of Units (SI). PMID:23252800

Dķaz, Sergio Cueto; Encinar, Jorge Ruiz; Sanz-Medel, Alfredo; Alonso, J Ignacio Garcķa

2013-01-07

86

Oxide Spintronics  

Microsoft Academic Search

Concomitant with the development of metal-based spintronics in the late 1980s and 1990s, important advances were made on the growth of high-quality oxide thin films and heterostructures. While this was at first motivated by the discovery of high-temperature superconductivity in perovskite Cu oxides, this technological breakthrough was soon applied to other transition-metal oxides and, notably, mixed-valence manganites. The discovery of

Manuel Bibes; Agns Barthelemy

2007-01-01

87

Development of Alkaline Oxidative Dissolution Methods for Chromium (III) Compounds Present in Hanford Site Tank Sludges  

SciTech Connect

The high-level radioactive waste sludge in the underground storage tanks at the Hanford Site contains various chromium solid phases. Dissolution and removal of chromium from tank waste sludges is desirable prior to high-level waste vitrification because increased volume is required to incorporate the residual chromium. Unfortunately, dissolution of chromium from the sludge to form Cr(OH){sub 4}{sup -} through treatment with heated NaOH solution (also used to dissolve aluminum phases and metathesize phosphates to sodium salts) generally has been unsuccessful in tests with both simulated and genuine Hanford waste sludges. Oxidative dissolution of the Cr(III) compounds to form soluble chromate has been proposed as an alternative chromium solid phase dissolution method and results of limited prior testing have been reported. The present systematic tests investigated oxygen gas, hydrogen peroxide, and sodium persulfate oxidants to dissolve Cr(III) under alkaline conditions to form soluble chromate. Permanganate and ozone also were considered for testing but were thought to be of secondary interest because of the insoluble residue (MnO{sub 2} from permanganate) and complex equipment (necessary to generate ozone) implicit with use of these reagents. The oxygen and hydrogen peroxide reagents leave no condensable residue and sodium persulfate only leaves soluble sodium sulfate. Crystalline Cr(OH){sub 3}, various hydrothermally aged amorphous Cr(III) oxide hydrates, mixed Fe(III)/Cr(III) oxide hydrates, and nickel and iron Cr(III) spinels, all of which have been identified or are likely constituents in Hanford tank wastes, were prepared and characterized for the dissolution tests. The effects of reagent and hydroxide concentrations, reaction temperature, and transition metal catalysts on reaction progress were investigated for each reagent as functions of reaction time. Reaction progress was measured by monitoring chromate concentration. Oxidation of chromium compounds by dissolved oxygen was found to increase linearly with oxygen partial pressure and NaOH concentration. The rate also increased with temperature at low activation energy, 26-36 kJ/mol, reflecting the opposing influences of decreasing oxygen volubility and increasing underlying chemical reaction rate. The reaction apparently proceeds by way of dissolved Cr(III) species, is catalyzed by Ni(II), and is slower for the hydrothermally aged materials. Dissolution rates ranged from about 7 x 10{sup -5} to 2.4 x 10{sup -4} moles Cr(III)/liter-hour in 80 C, 3-M NaOH with one atmosphere pure oxygen for the various Cr(III) compounds tested. These low dissolution rates commend the use of oxygen reagent to waste tank processing where extended residence times maybe practical. Oxidative dissolution of Cr(III) compounds by hydrogen peroxide was hampered in the presence of greater than 0.5 g Fe(III)/liter and other catalysts for H{sub 2}O{sub 2} decomposition and was less effective for materials that had undergone prolonged aging at high temperatures. Leaching was optimized at low excess NaOH and high temperatures (activation energy of {approx}82 kJ/mol). To prevent excessive loss of H{sub 2}O{sub 2} to catalytic decomposition, the peroxide reagent must be added slowly and with intense stirring. Treatment of waste solids with H{sub 2}O{sub 2} may only be attractive for freshly formed Cr(III) hydroxides [formed, for example, by alkaline metathesis of Cr(III)-bearing sludges] in the absence of decomposition catalysts such as Fe(III).

Delegard, Calvin H.; Krot, N N.; Shilov, V P.; Fedoseev, A M.; Budantseva, N A.; Nikonov, M V.; Yusov, A B.; Garnov, A Y.; Charushnikova, I A.; Perminov, V P.; Astafurova, L N.; Lapitskaya, T S.; Makarenkov, V I.

1999-07-02

88

Spectrophotometric detection of iodide and chromic (III) in urine after oxidation to iodine and chromate (VI).  

PubMed

Tests for oxidizing adulterants in urine are a continuing challenge to the drug-testing program. Iodine was found to destroy morphine and 6-acetylmorphine almost immediately. The effects were less evident on 11 -nor-delta9-tetrahydrocannabinol-9-carboxylic acid (THC-acid). When the urine solution was tested for iodine by a chromogenic substrate, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), no iodine was detected. Masking drug and adulterant simultaneously made iodine a preferred oxidizing adulterant for drug abusers. In this study, the reduced iodide was oxidized by sodium nitrite to iodine. The excess nitrite was decomposed by sulfamic acid and the iodine was detected by ABTS. Linearity was 12.7 to 635 mg/L (0.1 to 5 mmol/L, y = 0.9966x + 0.0016, R2 = 1.0000). Precisions (coefficient of variation) were within +/- 4.1% and quantitative accuracies were within 97% of expected values (n=5). Chromate, iodate, periodate, and persulfate interfered with the method. To alleviate the problem, the positive specimens were tested again by an iodine-specific method. After oxidation, the samples were treated with sodium azide and ammonium thiocyanate. In presence of thiocyanate, the azide reduced iodine to iodide almost immediately, and the solutions showed negative response to ABTS. The results were compared with that of a control group tested without thiocyanate. When iodine was present, the ratios of thiocyanate to control were less than 6%. Chromate was also found to destroy THC-acid in urine, and during storage most of the chromate changed to chromic (III). In this study, chromic was oxidized to chromate by hydrogen peroxide and sodium hydroxide and detected by 1,5-diphenylcarbazide. Linearity was 5.2 to 156 mg/L (0.1 to 3.0 mmol/L, y = 1.0285x - 0.0034, R2 = 0.9998). Precisions were within +/- 8.5% and quantitative accuracies were within 92% of expected values (n=5). The test was not interfered by other oxidizing agents. Both iodide and chromic oxidation methods showed urine backgrounds less than 1.27 and 0.52 mg/L, respectively (< 0.01 mmol/L). It indicated that a response more than 10 times of the background could be considered as oxidant contamination or adulteration of urine specimens. PMID:16419396

Paul, Buddha D; Jacobs, Aaron

2005-10-01

89

Yttrium oxide stabilized zirconium oxide  

SciTech Connect

This patent describes a process comprising: (a) forming a solution by mixing yttrium hydroxide and a sufficient amount of an aqueous solution of acetic acid to dissolve the yttrium hydroxide. The solution has a concentration of yttrium ion of about 5% to about 20% by weight of the solution, (b) adding from about 80% to about 95% by weight of zirconium oxide having a particle size range from about 1 to about 5 microns to yield a Zr to Y weight ratio of from about 4:1 to about 19:1 and thereby forming a slurry, (c) spray drying the slurry to form spherical agglomerates consisting essentially of zirconium oxide and a relatively uniform distribution of yttrium acetate whereby the agglomerates have a size from about 20 to about 200 micrometers, (d) heating the agglomerates to about 600/sup 0/C to about 700/sup 0/C in a neutral or oxidizing atmosphere to convert yttrium acetate to yttrium oxide to thereby form zirconium oxide yttrium oxide agglomerates with about 5% to about 20% by weight of yttrium oxide.

Ritsko, J.E.; Houck, D.L.; Acla, H.L.R.

1987-09-22

90

Chemical Conversion of PON to Nitrous Oxide for Nitrogen Isotopic Analysis : High- Sensitivity Tracer Assay for Nitrogen Fixation  

NASA Astrophysics Data System (ADS)

We present a method for high-sensitivity nitrogen isotopic analysis of particulate organic nitrogen (PON) in seawater and freshwater, for the aim of measuring the rate of nitrogen fixation through 15N2 tracer technique for samples that contain low numeric abundance of organisms. The method composed of the traditional oxidation/reduction methods: such as oxidation of PON to nitrate using persulfate, the reduction of nitrate to nitrite using spongy cadmium, and further reduction of nitrite to nitrous oxide using sodium azide in an acetic acid buffer. Then, Nitrous oxide is purged from the water and trapped cryogenically with subsequent release into a gas chromatography column to analyze stable nitrogen isotopic compositions using a continuous-flow isotope ratio mass spectrometer. A standard deviation less than 0.3 ‰ for nitrogen was found for PON samples containing more than 80 nmolN, with a blank nitrogen of 20 nmolN. Nitrogen isotopic fractionation were consistent within each batch of analysis. Besides, we found that we can also determine nitrogen isotopic compositions of total dissolved nitrogen (TDN, sum of NO3-, NO2-, ammonium, and DON), by applying the method for filtrate samples. Our method may prove to obtain isotopic information for lower quantities of PON and TDN than other methods, so that we can reduce quantities of water samples needed for incubation to determine the nitrogen fixation rate in both seawater and freshwater. Besides, the method is also useful to determine the rate of nitrogen fixation by the small size fraction in ocean. We will also present the results obtained at western subtropical North Pacific to support our conclusions.

Tsunogai, U.; Kido, T.; Hirota, A.; Ohkubo, S.; Komatsu, D. D.; Nakagawa, F.

2006-12-01

91

Improved method for the determination of nonpurgeable suspended organic carbon in natural water by silver filter filtration, wet chemical oxidation, and infrared spectrometry  

NASA Astrophysics Data System (ADS)

Precision and accuracy are reported for the first time for the analysis of nonpurgeable suspended organic carbon by silver membrane filtration followed by wet chemical oxidation. A water sample is pressure filtered through a 0.45-?m-pore-size, 47-mm-diameter silver membrane filter. The silver membrane filter then is cut into ribbons and placed in a flame-sealable glass ampule. The organic material trapped on the membrane filter strips is acidified, purged with oxygen to remove inorganic carbonates and volatile organic compounds, and oxidized to carbon dioxide (CO2) using phosphoric acid and potassium persulfate in the sealed glass ampule. The resulting CO2 is measured by a nondispersive infrared CO2 detector. The amount of CO2 is proportional to the concentration of chemically oxidizable nonpurgeable organic carbon in the environmental water sample. The quantitation and method detection limit for routine analysis is 0.2 mg/L. The average percent recovery in five representative matrices was 97 ± 11%. The errors associated with sampling and sample preparation of nonpurgeable suspended organic carbon are also described.

Burkhardt, Mark R.; Brenton, Ronald W.; Kammer, James A.; Jha, Virenda K.; O'Mara-Lopez, Peggy G.; Woodworth, Mark T.

1999-01-01

92

Oxide Thermoelectrics  

SciTech Connect

Thermoelectricity in oxides, especially NaxCoO2 and related materials, is discussed from the point of view of first principles calculations and Boltzmann transport theory. The electronic structure of this material is exceptional in that it has a combination of very narrow bands and strong hybridization between metal d states and ligand p states. As shown within the framework of conventional Boltzmann transport theory, this leads to high Seebeck coefficients even at metallic carrier densities. This suggests a strategy of searching for other narrow band oxides that can be doped metallic with mobile carriers. Some possible avenues for finding such materials are suggested.

Singh, David J [ORNL

2008-01-01

93

NITROGEN OXIDES  

EPA Science Inventory

This report is a review of current knowledge of the environmental health basis for control of manmade sources of nitrogen oxide emissions. The literature review covered the period through 1974. The principal subject areas considered in the report include: sources and control of a...

94

Hydrogen implanted silicon oxidation  

Microsoft Academic Search

The oxidation rate and the oxide thickness of the hydrogen ion implanted silicon wafers were examined. It was observed that the native oxide thickness is higher for the H+ implanted Si(100) compared to the Si(111). Also the native oxide thickness depended on the implanted hydrogen distribution. The thickness increased with the hydrogen con-centration. The oxide thickness after wet oxidization of

S. Hava; B. M. Lacquet; P. L. Swart

1989-01-01

95

Zirconium oxide  

SciTech Connect

Zirconium is a more commonly occurring element than is widely recognized: it ranks as the 20th most abundant element in the Earth's crust at 220 ppm. In fact, zirconium is present in over 37 different mineral forms; examples are schists, gneiss, iron ore beds, and even granite. The two commercially most important sources of zirconium are zircon and baddeleyite. Both baddeleyite and zircon contain a small amount (about 2% by weight on an oxide basis) of hafnium. Structurally and chemically hafnia is so similar to zirconia that its presence has little effect on the properties of the zirconia. For the purpose of the article, the 98:2 ZrO{sub 2} {center dot} HfO{sub 2} will be referred to as zirconia.

Heathcote, R. (Magnesium Elektron, Ltd., Swinton, Manchester (GB))

1992-05-01

96

Zinc Oxide Stabilized Zirconia.  

National Technical Information Service (NTIS)

Zinc oxide stabilized zirconia containing zirconia in cubic phase is prepared by evaporating zirconia and zinc oxide and depositing zirconia and zinc oxide on an atomic scale on a substrate. The stabilized zirconia resists corrosion at high temperatures a...

S. B. Qadri E. F. Skelton P. Lubitz

1997-01-01

97

Hydrogen implanted silicon oxidation  

Microsoft Academic Search

The oxidation rate and the oxide thickness of the hydrogen ion implanted silicon wafers were examined. It was observed that\\u000a the native oxide thickness is higher for the H+ implanted Si(100) compared to the Si(111). Also the native oxide thickness depended on the implanted hydrogen distribution.\\u000a The thickness increased with the hydrogen con-centration. The oxide thickness after wet oxidization of

S. Hava; B. M. Lacquet; P. L. Swart

1989-01-01

98

Fusion neutronics-streaming, shielding, heating, activation  

NASA Astrophysics Data System (ADS)

The International Thermonuclear Experimental Reactor (ITER) represents an important step towards a fusion power plant. Controlled fusion will be realized in a d-t-plasma magnetically confined by a Tokamak configuration. The first wall of the plasma chamber, blanket and vacuum vessel of ITER form a compact assembly for converting the kinetic energy of fusion neutrons into heat while simultaneously shielding the superconducting coils efficiently against neutron and accompanying photon radiation. This shielding system can be investigated with neutrons generated by low-energy accelerators. We report on experiments concerning shielding and streaming properties of a mock-up where energy spectra of both neutrons and protons were measured. They are compared with predictions of Monte Carlo calculations (code MCNP-4A) using various data libraries. The agreement justified the use of measured spectra as basis to calculate design parameters such as neutron and photon heating, radiation damage, gas production, and activation. Some of these parameters were also directly measured. The results validate the ITER design. .

Freiesleben, H.; Richter, D.; Seidel, K.; Unholzer, S.

2001-07-01

99

Oxidation decomposition of nitrogen-sulfur oxides  

SciTech Connect

The oxidative decomposition of nitrogen-sulfur oxides, formed by the reaction of nitrite ion and hydrogen sulfite ion in aqueous solution, has been investigated. The oxidants used in this study included hydrogen peroxide, nitrogen dioxide, and ozone. There was a wide range of susceptibility to oxidation among the compounds studied. Ozone was a better oxidant than nitrogen dioxide and hydrogen peroxide under the conditions used. The rate expression for the reaction of hydrogen peroxide with hydroxylamine was found to be -d[H[sub 2]O[sub 2

Littlejohn, D.; Chang, S.G. (Lawrence Berkeley Lab., CA (United States). Energy Environment Division)

1994-03-01

100

Biocompatibility of Graphene Oxide  

Microsoft Academic Search

Herein, we report the effects of graphene oxides on human fibroblast cells and mice with the aim of investigating graphene oxides' biocompatibility. The graphene oxides were prepared by the modified Hummers method and characterized by high-resolution transmission electron microscope and atomic force microscopy. The human fibroblast cells were cultured with different doses of graphene oxides for day 1 to day

Kan Wang; Jing Ruan; Hua Song; Jiali Zhang; Yan Wo; Shouwu Guo; Daxiang Cui

2011-01-01

101

Diabetes and Oxidant Stress  

Microsoft Academic Search

Diabetes is associated with chronic micro- and macrovascular complications. Oxidative stress has been defined as ‘a “shift\\u000a in the pro-oxidant – antioxidant balance in the pro-oxidant direction’.” Oxidant stress may initiate and exacerbate vascular\\u000a (endothelial) damage through excess production of reactive oxygen species, depletion of nitric oxide, and damage to lipids,\\u000a proteins, and DNA. Experimental results and theoretical constructs suggest

Alicia J. Jenkins; Michael A. Hill; Kevin G. Rowley

102

The enzymatic oxidation of graphene oxide.  

PubMed

Two-dimensional graphitic carbon is a new material with many emerging applications, and studying its chemical properties is an important goal. Here, we reported a new phenomenon--the enzymatic oxidation of a single layer of graphitic carbon by horseradish peroxidase (HRP). In the presence of low concentrations of hydrogen peroxide (?40 ?M), HRP catalyzed the oxidation of graphene oxide, which resulted in the formation of holes on its basal plane. During the same period of analysis, HRP failed to oxidize chemically reduced graphene oxide (RGO). The enzymatic oxidation was characterized by Raman, ultraviolet-visible, electron paramagnetic resonance, Fourier transform infrared spectroscopy, transmission electron microscopy, atomic force microscopy, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and gas chromatography-mass spectrometry. Computational docking studies indicated that HRP was preferentially bound to the basal plane rather than the edge for both graphene oxide and RGO. Owing to the more dynamic nature of HRP on graphene oxide, the heme active site of HRP was in closer proximity to graphene oxide compared to RGO, thereby facilitating the oxidation of the basal plane of graphene oxide. We also studied the electronic properties of the reduced intermediate product, holey reduced graphene oxide (hRGO), using field-effect transistor (FET) measurements. While RGO exhibited a V-shaped transfer characteristic similar to a single layer of graphene that was attributed to its zero band gap, hRGO demonstrated a p-type semiconducting behavior with a positive shift in the Dirac points. This p-type behavior rendered hRGO, which can be conceptualized as interconnected graphene nanoribbons, as a potentially attractive material for FET sensors. PMID:21344859

Kotchey, Gregg P; Allen, Brett L; Vedala, Harindra; Yanamala, Naveena; Kapralov, Alexander A; Tyurina, Yulia Y; Klein-Seetharaman, Judith; Kagan, Valerian E; Star, Alexander

2011-02-23

103

The Enzymatic Oxidation of Graphene Oxide  

PubMed Central

Two-dimensional graphitic carbon is a new material with many emerging applications, and studying its chemical properties is an important goal. Here, we reported a new phenomenon – the enzymatic oxidation of a single layer of graphitic carbon by horseradish peroxidase (HRP). In the presence of low concentrations of hydrogen peroxide (~40 µM), HRP catalyzed the oxidation of graphene oxide, which resulted in the formation of holes on its basal plane. During the same period of analysis, HRP failed to oxidize chemically reduced graphene oxide (RGO). The enzymatic oxidation was characterized by Raman, UV-Vis, EPR and FT-IR spectroscopy, TEM, AFM, SDS-PAGE, and GC-MS. Computational docking studies indicated that HRP was preferentially bound to the basal plane rather than the edge for both graphene oxide and RGO. Due to the more dynamic nature of HRP on graphene oxide, the heme active site of HRP was in closer proximity to graphene oxide compared to RGO, thereby facilitating the oxidation of the basal plane of graphene oxide. We also studied the electronic properties of the reduced intermediate product, holey reduced graphene oxide (hRGO), using field-effect transistor (FET) measurements. While RGO exhibited a V-shaped transfer characteristic similar to a single layer of graphene that was attributed to its zero band gap, hRGO demonstrated a p-type semiconducting behavior with a positive shift in the Dirac points. This p-type behavior rendered hRGO, which can be conceptualized as interconnected graphene nanoribbons, as a potentially attractive material for FET sensors.

Kotchey, Gregg P.; Allen, Brett L.; Vedala, Harindra; Yanamala, Naveena; Kapralov, Alexander A.; Tyurina, Yulia Y.; Klein-Seetharaman, Judith; Kagan, Valerian E.; Star, Alexander

2011-01-01

104

Nitrous Oxide and Tremor.  

National Technical Information Service (NTIS)

Standing steadiness and postural tremor were measured for seven subjects while breathing nitrous oxide. Concentrations of nitrous oxide were twelve, eighteen, twenty-nine, and thirty-four percent. Measurements were also made while subjects breathed pure o...

R. C. Carter M. K. Mewha L. E. Lash

1975-01-01

105

Electrolytic oxidation of anthracite  

USGS Publications Warehouse

An anthracite slurry can be oxidized only with difficulty by electrolytic methods in which aqueous electrolytes are used if the slurry is confined to the region of the anode by a porous pot or diaphragm. However, it can be easily oxidized if the anthracite itself is used as the anode. No porous pot or diaphragm is needed. Oxidative consumption of the coal to alkali-soluble compounds is found to proceed preferentially at the edges of the aromatic planes. An oxidation model is proposed in which the chief oxidants are molecular and radical species formed by the electrolytic decomposition of water at the coal surface-electrolyte interface. The oxidation reactions proposed account for the opening of the aromatic rings and the subsequent formation of carboxylic acids. The model also explains the observed anisotropic oxidation and the need for the porous pot or diaphragm used in previous studies of the oxidation of coal slurries. ?? 1981.

Senftle, F. E.; Patton, K. M.; Heard, Jr. , I.

1981-01-01

106

Mixed Acid Oxidation  

SciTech Connect

Several non-thermal processes have been developed to destroy organic waste compounds using chemicals with high oxidation potentials. These efforts have focused on developing technologies that work at low temperatures, relative to incineration, to overcome many of the regulatory issues associated with obtaining permits for waste incinerators. One such technique with great flexibility is mixed acid oxidation. Mixed acid oxidation, developed at the Savannah River Site, uses a mixture of an oxidant (nitric acid) and a carrier acid (phosphoric acid). The carrier acid acts as a non-volatile holding medium for the somewhat volatile oxidant. The combination of acids allows appreciable amounts of the concentrated oxidant to remain in the carrier acid well above the oxidant''s normal boiling point.

Pierce, R.A.

1999-10-26

107

Radiation Hardened Field Oxide.  

National Technical Information Service (NTIS)

This paper describes the development of a radiation-tolerant field oxide compatible with both MOS and bipolar technologies. Data is presented which illustrates that nonguardbanded devices utilizing conventional field oxide structures cannot be expected to...

J. R. Adams W. R. Dawes T. J. Sanders

1977-01-01

108

Oxidation of Aluminum Nitride.  

National Technical Information Service (NTIS)

The oxidation characteristics of hot-pressed aluminum nitride were investigated. Three materials were studied in the temperature range 1100 to 1400 C in 15, 150, and 400 torr oxygen environments. The oxidation process was evaluated using thermogravimetric...

B. A. Rasmussen

1973-01-01

109

Zinc oxide overdose  

MedlinePLUS

Zinc oxide is an ingredient in many products, including certain creams and ointments used to prevent or treat minor skin burns and irritation. Zinc oxide overdose occurs when someone accidentally or intentionally ...

110

Oxidative stress and anxiety  

PubMed Central

High O2 consumption, modest antioxidant defenses and a lipid-rich constitution make the brain highly vulnerable to redox imbalances. Oxidative damage in the brain causes nervous system impairment. Recently, oxidative stress has also been implicated in depression, anxiety disorders and high anxiety levels. The findings which establish a link between oxidative stress and pathological anxiety have inspired a number of other recent studies focusing on the link between oxidative status and normal anxiety and also on a possible causal relationship between cellular oxidative stress and emotional stress. This review examines the recent discoveries made on the link between oxidative status and normal anxiety levels and the putative role of oxidative stress in genesis of anxiety. We discuss the different opinions and questions that exist in the field and review the methodological approaches that are being used to determine a causal relationship between oxidative and emotional stress.

Rammal, Hassan; Soulimani, Rachid

2009-01-01

111

Transpassive oxidation of pyrite  

Microsoft Academic Search

The electrochemical behavior of mineral and coal pyrites in basic borate\\/sulfate solutions was investigated using cyclic voltammetry with both stationary and rotating disk electrode. Emphasis was centered on transpassive oxidation. In the transpassive region, 0.4 to 0.8 V (SCE), aggressive oxidation of pyrite occurred. The reaction products in this region are Fe(III) oxides, sulfate ion, and partially oxidized sulfur intermediates.

Ximeng Zhu; D. M. Bodily; M. E. Wadsworth

1993-01-01

112

Nanobelts of Semiconducting Oxides  

Microsoft Academic Search

Ultralong beltlike (or ribbonlike) nanostructures (so-called nanobelts) were successfully synthesized for semiconducting oxides of zinc, tin, indium, cad- mium, and gallium by simply evaporating the desired commercial metal oxide powders at high temperatures. The as-synthesized oxide nanobelts are pure, structurally uniform, and single crystalline, and most of them are free from defects and dislocations. They have a rectanglelike cross section

H. Iikura; S. Mori; M. Sawamura; E. Nakamura; Zheng Wei Pan; Zu Rong Dai; Zhong Lin Wang

2001-01-01

113

The effect of native oxide on thin gate oxide integrity  

Microsoft Academic Search

We have studied the effect of native oxide on thin gate oxide integrity. Much improved leakage current of gate oxide can be obtained by in situ desorbing the native oxide using HF-vapor treated and H2 baked processes. Furthermore, an extremely sharp interface between oxide and Si is obtained, and good oxide reliability is achieved even under a high current density

Albert Chin; B. C. Lin; W. J. Chen; Y. B. Lin; C. Tsai

1998-01-01

114

A Microscale Oxidation Puzzle  

NASA Astrophysics Data System (ADS)

We have adapted oxidation of an alcohol with sodium hypochlorite solution to a "puzzle" approach by using a diol as the substrate for oxidation. The diols under investigation have both a primary and a secondary hydroxyl group. There are three possible outcomes to the reaction: (i) only the primary alcohol is oxidized to the aldehyde (or carboxylic acid); (ii) only the secondary alcohol is oxidized to the ketone; or (iii) both alcohols are oxidized. The assignment is to perform the reaction and determine the structure of the product through interpretation of the IR spectrum. Examples using two commercially available diols are shown.

Pelter, Michael W.; Macudzinski, Rebecca M.; Passarelli, Mary Ellen

2000-11-01

115

ZIRCONIUM OXIDE NANOSTRUCTURES PREPARED BY ANODIC OXIDATION  

SciTech Connect

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

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

2008-01-01

116

Zirconium Oxide Nanostructures Prepared by Anodic Oxidation  

SciTech Connect

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

Dang, Ying Yi [ORNL; Bhuiyan, Md S [ORNL; Paranthaman, Mariappan Parans [ORNL

2008-01-01

117

High Latitude Nitrogen Oxide oxidation during wintertime  

NASA Astrophysics Data System (ADS)

Nitrogen oxides are key chemicals in the atmosphere that affect ozone levels and eventually are oxidized to nitric acid, leading to acidification and fertilization where they are deposited. During high-latitude wintertime conditions, photochemical removal pathways slow due to lack of sunlight and ozone oxidizes NO2 to NO3, which reacts with NO2 to form dinitrogen pentoxide (N2O5) that then hydrolyses to nitric acid on water-containing surfaces. Modeling studies indicate that this "dark" pathway is responsible for the majority of nitrogen oxide removal at high latitudes during winter. However, little is known about the surfaces on which the hydrolysis takes place and how ambient conditions affect this pathway. In a series of field campaigns, our group has measured ambient mixing ratios of N2O5 and its precursors and sinks so as to understand nighttime nitrogen oxide removal under high latitude conditions. We find that airmasses saturated with respect to ice have significantly shorter N2O5 lifetimes than sub-saturated airmasses, indicating a significant role for ice surfaces in the dark oxidation pathway. Airmasses that are saturated with respect to ice may contain small ice particles that act as heterogeneous reaction sites or saturation with respect to ice could result from airmass contact with the snowpack, indicating N2O5 is deposited to the snow surface. In this presentation, we discuss these possible losses and implications for chemistry in high-latitude pollution plumes.

Apodaca, R. L.; Huff, D. M.; Simpson, W. R.

2008-12-01

118

Mechanism of N(5)-ethyl-flavinium cation formation upon electrochemical oxidation of N(5)-ethyl-4a-hydroxyflavin pseudobase.  

PubMed

We investigated the oxidation behavior of 5-ethyl-4a-hydroxy-3-methyl-4a,5-dihydrolumiflavin (pseudobase Et-FlOH) in acetonitrile with the aim of determining if the two-electron oxidized Et-FlOH(2+) undergoes a release of hydroxyl cation and the production of 5-ethyl-3methyllumiflavinium cation (Et-Fl(+)). The focus of this work is to investigate the possibility of using Et-FlOH as a catalyst for water oxidation. The cyclic voltammetry demonstrates that Et-FlOH exhibits two one-electron oxidation potentials at +0.95 and +1.4 V versus normal hydrogen electrode (NHE), with the second oxidation potential being irreversible. The production of Et-Fl(+) is observed in the cyclic voltammetry of Et-FlOH and has been previously assigned to the release of OH(+) from the two-electron oxidized Et-FlOH(2+). The results of our study show that this is not the case: (i) we performed bulk electrolysis of the electrolyte solution at +2 V and then added Et-FlOH to the electrolyzed solution. We found that Et-Fl(+) is produced from this solution, even though Et-FlOH itself was not oxidized; (ii) reactions of Et-FlOH with chemical oxidants (ceric ammonium nitrate, nitrosyl tetrafluoroborate, and tetrabutylammonium persulfate) demonstrate that Et-Fl(+) production occurs only in the presence of strong Lewis acids, such as Ce(4+) and NO(+) ions. On the basis of these results, we propose that the production of Et-Fl(+) in the electrochemistry of Et-FlOH occurs because of the shift in the Et-FlOH/Et-Fl(+) acid-base equilibrium in the presence of protons released during anodic oxidation. We identified two sources of protons: (i) oxidation of traces of water present in the acetonitrile releases oxygen and protons and (ii) two-electron oxidized Et-FlOH(2+) releases protons located on the N(5)-alkyl chain. The release of protons from Et-FlOH(2+) was confirmed by cyclic voltammetry of Et-FlOH in the presence of pyridine as a base. The first oxidation peak of Et-FlOH at +0.95 V is reversible in the absence of pyridine. The addition of pyridine leads to the shift of the oxidation potential to a less positive value, which is consistent with a proton-coupled electron transfer (PCET). Furthermore, the anodic current increases, and the cathodic peak becomes irreversible, giving rise to two additional reduction peaks at -0.2 and -1 V. The same reduction peaks were observed in the high scan rate cyclic voltammogram of Et-FlOH in the absence of pyridine, implying that the release of protons indeed occurs from Et-FlOH(2+). To determine which functional group of Et-FlOH(.+) is the source of protons, we performed DFT calculations at the B3LYP/6-311++G** level of theory for a reaction of Et-FlOH(.+) with pyridine and identified two proton sources: (i) the >N-CH(2)- group of the N(5) alkyl chain and (ii) the -OH group in the 4a-position of the radical cation. Because the appearance of new reduction peaks at -0.2 and -1.0 V occurs in the model compound that lacks -OH protons (Et-FlOMe), we conclude that the proton removal occurs predominantly from the >N-CH(2)- moiety. PMID:20597524

Sichula, Vincent; Hu, Ying; Mirzakulova, Ekaterina; Manzer, Samuel F; Vyas, Shubham; Hadad, Christopher M; Glusac, Ksenija D

2010-07-29

119

Mechanisms of DNA oxidation.  

PubMed

Oxidative damage of DNA caused by a variety of chemical and physical agents appears to be linked to cancer. However, it is becoming increasingly clear that endogenous generation of oxidants, such as hydroxyl radical and peroxynitrite, lead to oxidation of DNA, and this may cause cancer in individuals where no obvious exposure to chemical or physical agents known to be carcinogenic has occurred. The mechanisms for generation of these two oxidants in living organisms will be discussed and their reactivities with DNA to produce oxidized products (e.g., 8-oxo-dG) will be presented with special emphasis on the individual characteristics of the generation and reactivity of each oxidant. PMID:10601883

Aust, A E; Eveleigh, J F

1999-12-01

120

Barium oxide, calcium oxide, magnesia, and alkali oxide free glass  

DOEpatents

A glass composition consisting essentially of about 10-45 mole percent of SrO; about 35-75 mole percent SiO.sub.2; one or more compounds from the group of compounds consisting of La.sub.2O.sub.3, Al.sub.2O.sub.3, B.sub.2O.sub.3, and Ni; the La.sub.2O.sub.3 less than about 20 mole percent; the Al.sub.2O.sub.3 less than about 25 mole percent; the B.sub.2O.sub.3 less than about 15 mole percent; and the Ni less than about 5 mole percent. Preferably, the glass is substantially free of barium oxide, calcium oxide, magnesia, and alkali oxide. Preferably, the glass is used as a seal in a solid oxide fuel/electrolyzer cell (SOFC) stack. The SOFC stack comprises a plurality of SOFCs connected by one or more interconnect and manifold materials and sealed by the glass. Preferably, each SOFC comprises an anode, a cathode, and a solid electrolyte.

Lu, Peizhen Kathy; Mahapatra, Manoj Kumar

2013-09-24

121

OXIDATION OF TRANSURANIC ELEMENTS  

DOEpatents

A method is reported for oxidizing neptunium or plutonium in the presence of cerous values without also oxidizing the cerous values. The method consists in treating an aqueous 1N nitric acid solution, containing such cerous values together with the trivalent transuranic elements, with a quantity of hydrogen peroxide stoichiometrically sufficient to oxidize the transuranic values to the hexavalent state, and digesting the solution at room temperature.

Moore, R.L.

1959-02-17

122

Vivianite auto-oxidation  

Microsoft Academic Search

Vivianite, Fe3(PO4)2×8 H2O, (010) surfaces cleaved in an N2 gas atmosphere are examined using X-ray photoelectron spectroscopy (XPS). Quantitative evaluation of Fe(2p32) and O(1s) spectra show cleaved surfaces are partly oxidized. Ferric hydroxide is identified as an oxidation product. An auto-reduction-oxidation mechanism involving rupture of hydrogen bonds between the H2O ligands which hold together the sheet structure of vivianite is

Allen R. Pratt

1997-01-01

123

Vivianite auto-oxidation  

NASA Astrophysics Data System (ADS)

Vivianite, Fe3(PO4)2×8 H2O, (010) surfaces cleaved in an N2 gas atmosphere are examined using X-ray photoelectron spectroscopy (XPS). Quantitative evaluation of Fe(2p32) and O(1s) spectra show cleaved surfaces are partly oxidized. Ferric hydroxide is identified as an oxidation product. An auto-reduction-oxidation mechanism involving rupture of hydrogen bonds between the H2O ligands which hold together the sheet structure of vivianite is proposed.

Pratt, Allen R.

124

METAL OXIDE NANOPARTICLES  

SciTech Connect

This chapter covers the fundamental science, synthesis, characterization, physicochemical properties and applications of oxide nanomaterials. Explains fundamental aspects that determine the growth and behavior of these systems, briefly examines synthetic procedures using bottom-up and top-down fabrication technologies, discusses the sophisticated experimental techniques and state of the art theory results used to characterize the physico-chemical properties of oxide solids and describe the current knowledge concerning key oxide materials with important technological applications.

FERNANDEZ-GARCIA,M.; RODGRIGUEZ, J.A.

2007-10-01

125

Iron oxide modified minerals  

Microsoft Academic Search

Composites of iron oxide nanoparticles immobilized on the surface of various clay mineral matrices (muscovite, montmorillonite\\u000a and vermiculite) have been prepared by the alkaline oxidative hydrolysis of iron sulphate in the presence of mineral matrices.\\u000a The composites have been studied by Mössbauer spectroscopy, XRD, TEM and SQUID. Correspondence between the hyperfine parameters\\u000a and the iron oxide particle size and magnetic

M. Mashlan; H. Bartonkova; D. Jancik; J. Tucek; P. Martinec

126

Iron oxide modified minerals  

Microsoft Academic Search

Composites of iron oxide nanoparticles immobilized on the surface of various clay mineral matrices (muscovite, montmorillonite\\u000a and vermiculite) have been prepared by the alkaline oxidative hydrolysis of iron sulphate in the presence of mineral matrices.\\u000a The composites have been studied by Mössbauer spectroscopy, XRD, TEM and SQUID. Correspondence between the hyperfine parameters\\u000a and the iron oxide particle size and magnetic

M. Mashlan; H. Bartonkova; D. Jancik; J. Tucek; P. Martinec

2009-01-01

127

40 CFR 268.45 - Treatment standards for hazardous debris.  

Code of Federal Regulations, 2012 CFR

...assisted ozone; (5) peroxides; (6) persulfates; (7) perchlorates; (8) permanganates; and/or (9) other oxidizing reagents...combination of reagents: (1) sulfur dioxide; (2) sodium, potassium, or alkali salts of sulfites, bisulfites, and...

2012-07-01

128

Mixed oxide solid solutions  

DOEpatents

The present invention is a mixed oxide solid solution containing a tetravalent and a pentavalent cation that can be used as a support for a metal combustion catalyst. The invention is furthermore a combustion catalyst containing the mixed oxide solid solution and a method of making the mixed oxide solid solution. The tetravalent cation is zirconium(+4), hafnium(+4) or thorium(+4). In one embodiment, the pentavalent cation is tantalum(+5), niobium(+5) or bismuth(+5). Mixed oxide solid solutions of the present invention exhibit enhanced thermal stability, maintaining relatively high surface areas at high temperatures in the presence of water vapor.

Magno, Scott (Dublin, CA); Wang, Ruiping (Fremont, CA); Derouane, Eric (Liverpool, GB)

2003-01-01

129

REVIEW OF PLUTONIUM OXIDATION LITERATURE  

Microsoft Academic Search

A brief review of plutonium oxidation literature was conducted. The purpose of the review was to ascertain the effect of oxidation conditions on oxide morphology to support the design and operation of the PDCF direct metal oxidation (DMO) furnace. The interest in the review was due to a new furnace design that resulted in oxide characteristics that are different than

Korinko

2009-01-01

130

Partial oxidation process  

SciTech Connect

A process is provided for the partial oxidation of a high metals or ash containing liquid hydrocarbonaceous fuel or a slurry of solid carbonaceous fuel to simultaneously produce saturated and unsaturated raw streams of synthesis gas, reducing gas, or fuel gas. Two continuous partial oxidation reactions in two separate reaction zones go on simultaneously. The fuel feed to the first partial oxidation zone is said fresh high metals or ash containing fuel. The raw product gas stream from the first partial oxidation zone is split into first and second split gas streams. The first split gas stream may be cooled in a radiant and/or convection type gas cooler without fouling heat exchange surfaces. The fuel feed to the second partial oxidation zone is a pumpable slurry which is prepared from the entrained matter that is separated from said gas streams during quench cooling and cleaning operations and which contains a comparatively high amount of metals and/or ash. The partial oxidation reaction takes place in the second partial oxidation zone in a reducing atmosphere that includes the second split raw product gas stream from the first partial oxidation zone. By the subject process, there is a reduction in the unconverted carbon produced without any significant loss in efficiency. Further, the life of the cooler for the raw product gas stream is increased.

Jahnke, F. C.

1985-10-15

131

Oxidation of Halocarbons.  

National Technical Information Service (NTIS)

The gas-phase room-temperature oxidation of haloethylenes was studied. In general oxidation has been carried out in five ways: (1) chlorine atom initiation, (2) Hg 6(triplet P) sensitization, (3) reaction with O(triplet P), (4) reaction with O(triplet P) ...

E. Sanhueza I. C. Hisatsune J. P. Keicklen R. Simonaitis R. K. M. Jayanty

1975-01-01

132

Oxidative stress in autism  

Microsoft Academic Search

Autism is a severe developmental disorder with poorly understood etiology. Oxidative stress in autism has been studied at the membrane level and also by measuring products of lipid peroxidation, detoxifying agents (such as glutathione), and antioxidants involved in the defense system against reactive oxygen species (ROS). Lipid peroxidation markers are elevated in autism, indicating that oxidative stress is increased in

Abha Chauhan; Ved Chauhan

2006-01-01

133

Lipid oxidation in foods  

Microsoft Academic Search

This review discusses the basic chemical reactions that affect food flavor quality. Although there are many reactions that can lead to the deterioration of quality in foods, this review focuses on lipid oxidation and how it adversely affects flavor principles. It also presents technological advances for studying the basic mechanism of lipid oxidation, for measuring its intensity, and for retaining

Allen J. St. Angelo; John Vercellotti; Tom Jacks; Michael Legendre

1996-01-01

134

OXIDATION OF CHLORINATED ETHANES  

EPA Science Inventory

The oxidation products of seven chlorinated ethanes were identified using Fourier Transform Spectroscopy and long path infrared techniques. Photo-oxidation of each chlorinated ethane was initiated by chlorine atoms in one atmosphere of dry air. The chlorinated reaction products i...

135

Conversion of nitrogen oxides  

Microsoft Academic Search

Zeolite catalyzed reduction of nitrogen oxides in exhaust gases is conducted with catalytic elements in the form of multi-channel structures in which parallel channels are defined by thin walls constituted by refractory oxides having zeolite dispersed therein and accessable to diffusion from surfaces of the channel walls. Such structures, preferably monolithic honeycomb forms, are prepared by calcining extruded or cast

S. M. Brown; G. M. Woltermann

1979-01-01

136

Thin Oxides with in situ Native Oxide Removal  

Microsoft Academic Search

We have studied the inversion layer mobility of n- MOSFET's with thin-gate oxide of 20 to 70 ? A. Direct relationship of electron mobility to oxide\\/channel interface roughness was ob- tained from measured mobility of MOSFET's and high-resolution TEM. By using a low-pressure oxidation process with native oxide removed in situ prior to oxidation, atomically smooth interface of oxide\\/channel was

Albert Chin; W. J. Chen; T. Chang; R. H. Kao; B. C. Lin; C. Tsai; M. Huang

1997-01-01

137

Total oxidation of methane over doped nanophase cerium oxides  

Microsoft Academic Search

The formation of solid solutions of cerium oxide with the oxides of calcium, manganese, or neodymium enhances the catalytic\\u000a activity of cerium oxide for the total oxidation of methane, whereas solid solutions with lead oxide showed an opposite effect.\\u000a Reasons for this are discussed in terms of oxygen vacancy concentrations and mobilities, local structure configurations, number\\u000a of oxidation states of

A. E. C. Palmqvist; E. M. Johansson; S. G. Jarasb; M. Muhammeda

1998-01-01

138

[Oxidative stress and magnesium].  

PubMed

The generation of reactive oxygen species and other free radicals during metabolism is a necessary and normal process that ideally is compensated for by an elaborate endogenous antioxidant system. However, due to many environmental, lifestyle, and pathological situations, excess radicals can accumulate, resulting in oxidative stress. Oxidative stress has been related to cardiovascular disease, cancer, and other chronic diseases that account for a major portion of deaths today. Antioxidants are compounds that hinder the oxidative processes and thereby delay or prevent oxidative stress. In this sense, magnesium is one of the physiological, efficient antioxidant. Magnesium plays a role in more than 300 enzymatic reactions and is critically involved in energy metabolism, glucose utilization, protein synthesis, fatty acid synthesis and breakdown, ATPase functions, and virtually all hormonal reactions. This article summarizes the process of oxidative stress and the pathways by which it relates to magnesium. PMID:15692157

Hasebe, Naoyuki

2005-02-01

139

Crystalline oxides on silicon.  

PubMed

This review outlines developments in the growth of crystalline oxides on the ubiquitous silicon semiconductor platform. The overall goal of this endeavor is the integration of multifunctional complex oxides with advanced semiconductor technology. Oxide epitaxy in materials systems achieved through conventional deposition techniques is described first, followed by a description of the science and technology of using atomic layer-by-layer deposition with molecular beam epitaxy (MBE) to systematically construct the oxide-silicon interface. An interdisciplinary approach involving MBE, advanced real-space structural characterization, and first-principles theory has led to a detailed understanding of the process by which the interface between crystalline oxides and silicon forms, the resulting structure of the interface, and the link between structure and functionality. Potential applications in electronics and photonics are also discussed. PMID:20432223

Reiner, James W; Kolpak, Alexie M; Segal, Yaron; Garrity, Kevin F; Ismail-Beigi, Sohrab; Ahn, Charles H; Walker, Fred J

2010-07-20

140

Biocompatibility of Graphene Oxide  

NASA Astrophysics Data System (ADS)

Herein, we report the effects of graphene oxides on human fibroblast cells and mice with the aim of investigating graphene oxides' biocompatibility. The graphene oxides were prepared by the modified Hummers method and characterized by high-resolution transmission electron microscope and atomic force microscopy. The human fibroblast cells were cultured with different doses of graphene oxides for day 1 to day 5. Thirty mice divided into three test groups (low, middle, high dose) and one control group were injected with 0.1, 0.25, and 0.4 mg graphene oxides, respectively, and were raised for 1 day, 7 days, and 30 days, respectively. Results showed that the water-soluble graphene oxides were successfully prepared; graphene oxides with dose less than 20 ?g/mL did not exhibit toxicity to human fibroblast cells, and the dose of more than 50 ?g/mL exhibits obvious cytotoxicity such as decreasing cell adhesion, inducing cell apoptosis, entering into lysosomes, mitochondrion, endoplasm, and cell nucleus. Graphene oxides under low dose (0.1 mg) and middle dose (0.25 mg) did not exhibit obvious toxicity to mice and under high dose (0.4 mg) exhibited chronic toxicity, such as 4/9 mice death and lung granuloma formation, mainly located in lung, liver, spleen, and kidney, almost could not be cleaned by kidney. In conclusion, graphene oxides exhibit dose-dependent toxicity to cells and animals, such as inducing cell apoptosis and lung granuloma formation, and cannot be cleaned by kidney. When graphene oxides are explored for in vivo applications in animal or human body, its biocompatibility must be considered.

Wang, Kan; Ruan, Jing; Song, Hua; Zhang, Jiali; Wo, Yan; Guo, Shouwu; Cui, Daxiang

2010-12-01

141

Biocompatibility of Graphene Oxide  

NASA Astrophysics Data System (ADS)

Herein, we report the effects of graphene oxides on human fibroblast cells and mice with the aim of investigating graphene oxides' biocompatibility. The graphene oxides were prepared by the modified Hummers method and characterized by high-resolution transmission electron microscope and atomic force microscopy. The human fibroblast cells were cultured with different doses of graphene oxides for day 1 to day 5. Thirty mice divided into three test groups (low, middle, high dose) and one control group were injected with 0.1, 0.25, and 0.4 mg graphene oxides, respectively, and were raised for 1 day, 7 days, and 30 days, respectively. Results showed that the water-soluble graphene oxides were successfully prepared; graphene oxides with dose less than 20 ?g/mL did not exhibit toxicity to human fibroblast cells, and the dose of more than 50 ?g/mL exhibits obvious cytotoxicity such as decreasing cell adhesion, inducing cell apoptosis, entering into lysosomes, mitochondrion, endoplasm, and cell nucleus. Graphene oxides under low dose (0.1 mg) and middle dose (0.25 mg) did not exhibit obvious toxicity to mice and under high dose (0.4 mg) exhibited chronic toxicity, such as 4/9 mice death and lung granuloma formation, mainly located in lung, liver, spleen, and kidney, almost could not be cleaned by kidney. In conclusion, graphene oxides exhibit dose-dependent toxicity to cells and animals, such as inducing cell apoptosis and lung granuloma formation, and cannot be cleaned by kidney. When graphene oxides are explored for in vivo applications in animal or human body, its biocompatibility must be considered.

Wang, Kan; Ruan, Jing; Song, Hua; Zhang, Jiali; Wo, Yan; Guo, Shouwu; Cui, Daxiang

2011-12-01

142

Biocompatibility of Graphene Oxide  

PubMed Central

Herein, we report the effects of graphene oxides on human fibroblast cells and mice with the aim of investigating graphene oxides' biocompatibility. The graphene oxides were prepared by the modified Hummers method and characterized by high-resolution transmission electron microscope and atomic force microscopy. The human fibroblast cells were cultured with different doses of graphene oxides for day 1 to day 5. Thirty mice divided into three test groups (low, middle, high dose) and one control group were injected with 0.1, 0.25, and 0.4 mg graphene oxides, respectively, and were raised for 1 day, 7 days, and 30 days, respectively. Results showed that the water-soluble graphene oxides were successfully prepared; graphene oxides with dose less than 20 ?g/mL did not exhibit toxicity to human fibroblast cells, and the dose of more than 50 ?g/mL exhibits obvious cytotoxicity such as decreasing cell adhesion, inducing cell apoptosis, entering into lysosomes, mitochondrion, endoplasm, and cell nucleus. Graphene oxides under low dose (0.1 mg) and middle dose (0.25 mg) did not exhibit obvious toxicity to mice and under high dose (0.4 mg) exhibited chronic toxicity, such as 4/9 mice death and lung granuloma formation, mainly located in lung, liver, spleen, and kidney, almost could not be cleaned by kidney. In conclusion, graphene oxides exhibit dose-dependent toxicity to cells and animals, such as inducing cell apoptosis and lung granuloma formation, and cannot be cleaned by kidney. When graphene oxides are explored for in vivo applications in animal or human body, its biocompatibility must be considered.

2011-01-01

143

Oxidation of phenols by chloroperoxidase  

Microsoft Academic Search

Summary Purified fungal chloroperoxidase oxidized a variety of substituted phenols at pH 3 and 5.5. Chlorophenols were oxidized most readily, followed by monomethyl—then dimethylphenols. Cyclohexanol and its monomethyl derivatives were not oxidized.

Robert Carmichael; Phillip M. Fedorak; Michael A. Pickard

1985-01-01

144

Nitric oxide and cardiovascular disease.  

PubMed Central

Endothelium-derived nitric oxide is an important regulatory molecule in cardiovascular function. Reduced availability of nitric oxide has been implicated in the pathogenesis of hypertension and atherosclerosis.

McIntyre, M.; Dominiczak, A. F.

1997-01-01

145

Oxidative stress in COPD.  

PubMed

Oxidative stress is now recognized as a major predisposing factor in the pathogenesis of COPD. Existing therapies for COPD are ineffective at halting disease progression, with bronchodilators being the mainstay of pharmacotherapy, providing symptomatic relief only. It is, therefore, important for a better understanding of the underlying mechanisms by which oxidative stress drives disease pathogenesis to develop novel and more effective therapies. Antioxidant capacity in COPD is substantially reduced as a result of cigarette smoking and exacerbations, with oxidative stress persisting long after the cessation of cigarette smoking or exacerbation, due to the continued production of reactive oxygen species from endogenous sources. We discuss (1) how oxidative stress arises in the lung, (2) how it is neutralized, (3) what genetic factors may predispose to the development of COPD, and (4) how this impacts inflammation and autoimmunity in the development of emphysema and small airways disease. Finally, various strategies have been considered to neutralize the increased oxidative burden present in COPD. This review highlights why current antioxidant strategies have so far failed and what promising alternatives are on the horizon. Moreover, a number of studies have shown that there is no single "magic bullet" to combat oxidative stress, but instead a combination therapy, targeting oxidative stress in the various subcellular compartments, may prove to be more effective in COPD. PMID:23880677

Kirkham, Paul A; Barnes, Peter J

2013-07-01

146

NEPTUNIUM OXIDE PROCESSING  

SciTech Connect

The Savannah River Site's HB-Line Facility completed a campaign in which fifty nine cans of neptunium oxide were produced and shipped to the Idaho National Laboratory in the 9975 shipping container. The neptunium campaign was divided into two parts: Part 1 which consisted of oxide made from H-Canyon neptunium solution which did not require any processing prior to conversion into an oxide, and Part 2 which consisted of oxide made from additional H-Canyon neptunium solutions which required processing to purify the solution prior to conversion into an oxide. The neptunium was received as a nitrate solution and converted to oxide through ion-exchange column extraction, precipitation, and calcination. Numerous processing challenges were encountered in order make a final neptunium oxide product that could be shipped in a 9975 shipping container. Among the challenges overcome was the issue of scale: translating lab scale production into full facility production. The balance between processing efficiency and product quality assurance was addressed during this campaign. Lessons learned from these challenges are applicable to other processing projects.

Jordan, J; Watkins, R; Hensel, S

2009-05-27

147

Vivianite auto-oxidation  

Microsoft Academic Search

Vivianite, Fe3(PO4)2×8?H2O, (010) surfaces cleaved in an N2 gas atmosphere are examined using X-ray photoelectron spectroscopy (XPS). Quantitative evaluation of Fe(2p\\u000a 32) and O(1s) spectra show cleaved surfaces are partly oxidized. Ferric hydroxide is identified as an oxidation product. An auto-reduction-oxidation\\u000a mechanism involving rupture of hydrogen bonds between the H2O ligands which hold together the sheet structure of vivianite is

Allen R. Pratt

1997-01-01

148

Oxidation of cornstarch using oxygen as oxidant without catalyst  

Microsoft Academic Search

In the present work, oxygen was used as an environmentally friendly oxidant without catalyst, resulting in a waste free and simple method for starch oxidation. The oxidation was performed under the conditions of oxygen in sodium hydroxide at about 100°C. It was found that the oxidation of the native cornstarch in this system depends upon the amount of sodium hydroxide,

Sheng Ye; Wang Qiu-hua; Xu Xue-Chun; Jiang Wen-yong; Gan Shu-Cai; Zou Hai-Feng

2011-01-01

149

High Current Oxide Cathodes.  

National Technical Information Service (NTIS)

The aim of the AASERT supported research is to develop the plasma deposition/implantation process for coating barium, strontium and calcium oxides on nickel substrates and to perform detailed surface analysis of the resultant materials as well as complete...

N. C. Luhmann

2000-01-01

150

Cathodoluminescence of Uranium Oxides.  

National Technical Information Service (NTIS)

The cathodoluminescence of uranium oxide surfaces prepared in-situ from clean uranium exposed to dry oxygen was studied. The broad asymmetric peak observed at 470 nm is attributed to F-center excitation. (ERA citation 09:043913)

K. Winer C. Colmenares F. Wooten

1984-01-01

151

Cathodoluminescence of uranium oxides  

SciTech Connect

The cathodoluminescence of uranium oxide surfaces prepared in-situ from clean uranium exposed to dry oxygen was studied. The broad asymmetric peak observed at 470 nm is attributed to F-center excitation.

Winer, K.; Colmenares, C.; Wooten, F.

1984-08-09

152

Dopamine Oxidation and Autophagy  

PubMed Central

The molecular mechanisms involved in the neurodegenerative process of Parkinson's disease remain unclear. Currently, there is a general agreement that mitochondrial dysfunction, ?-synuclein aggregation, oxidative stress, neuroinflammation, and impaired protein degradation are involved in the neurodegeneration of dopaminergic neurons containing neuromelanin in Parkinson's disease. Aminochrome has been proposed to play an essential role in the degeneration of dopaminergic neurons containing neuromelanin by inducing mitochondrial dysfunction, oxidative stress, the formation of neurotoxic ?-synuclein protofibrils, and impaired protein degradation. Here, we discuss the relationship between the oxidation of dopamine to aminochrome, the precursor of neuromelanin, autophagy dysfunction in dopaminergic neurons containing neuromelanin, and the role of dopamine oxidation to aminochrome in autophagy dysfunction in dopaminergic neurons. Aminochrome induces the following: (i) the formation of ?-synuclein protofibrils that inactivate chaperone-mediated autophagy; (ii) the formation of adducts with ?- and ?-tubulin, which induce the aggregation of the microtubules required for the fusion of autophagy vacuoles and lysosomes.

Munoz, Patricia; Huenchuguala, Sandro; Paris, Irmgard; Segura-Aguilar, Juan

2012-01-01

153

Oxidative Stress and Neurodegeneration  

Microsoft Academic Search

Oxidative stress is a well-studied early response in chronic neurodegenerative diseases, including Alzheimer's disease, where neuronal loss can exceed 90% in the vulnerable neuronal population. Oxidative stress affects all classes of macromolecules (sugar, lipids, proteins, and DNA), leading inevitably to neuronal dysfunction. We observed that N?-(carboxymethyl)lysine (CML), the predominant advanced glycation end product that accumulates in vivo, along with its

Paula I. Moreira; Mark A. Smith; Xiongwei Zhu; Akihiko Nunomura; Rudy J. Castellani; George Perry

2005-01-01

154

Wet air oxidation  

Microsoft Academic Search

Wet air oxidation (WAO), involving oxidation at high temperature (125--320 C) and pressure (0.5--20 MPa) conditions, is useful for the treatment of hazardous, toxic, and nonbiodegradable waste streams. The process becomes self-sustaining when the feed chemical oxygen demand (COD) is about 20,000 mg\\/l and can be a net energy producer at sufficient higher feed COD's. All the published information on

Vedprakash S. Mishra; Vijaykumar V. Mahajani; Jyeshtharaj B. Joshi

1995-01-01

155

Metal atom oxidation laser  

DOEpatents

A chemical laser which operates by formation of metal or carbon atoms and reaction of such atoms with a gaseous oxidizer in an optical resonant cavity is described. The lasing species are diatomic or polyatomic in nature and are readily produced by exchange or other abstraction reactions between the metal or carbon atoms and the oxidizer. The lasing molecules may be metal or carbon monohalides or monoxides.

Jensen, R.J.; Rice, W.W.; Beattie, W.H.

1975-10-28

156

Metal atom oxidation laser  

DOEpatents

A chemical laser which operates by formation of metal or carbon atoms and reaction of such atoms with a gaseous oxidizer in an optical resonant cavity is described. The lasing species are diatomic or polyatomic in nature and are readily produced by exchange or other abstraction reactions between the metal or carbon atoms and the oxidizer. The lasing molecules may be metal or carbon monohalides or monoxides. (auth)

Jensen, R.J.; Rice, W.W.; Beattie, W.H.

1975-10-28

157

Thermopower in cobalt oxides  

Microsoft Academic Search

We study theoretically the thermopower in cobalt oxides generalizing the Heikes formula. In the oxides, states of carriers are largely degenerate because the crystalline field and Hund's rule coupling compete in cobalt ions. It is shown that the degeneracy, together with strong correlation of 3d electrons, causes the large thermopower. The recent experiments in NaCo2O4 are discussed in the light

W. Koshibae; K. Tsutsui; S. Maekawa

2000-01-01

158

Oxidation of orthopaedic UHMWPE  

Microsoft Academic Search

Retrieved EtO sterilised acetabular cups usually show much less degradation than ?-ray sterilised cups. Some of our retrieved EtO sterilised cups did, however, reveal unexpected bulk oxidation. It was observed that this oxidation was always accompanied by whitening of the material. This whitening was found to be due to a break-up of the compression moulded material into its original particles.

L. Costa; K. Jacobson; P. Bracco; E. M. Brach del Prever

2002-01-01

159

Oxidative methane upgrading.  

PubMed

The economically viable oxidative upgrading of methane presents one of the most difficult but rewarding challenges within catalysis research. Its potential to revolutionalise the chemical value chain, coupled with the associated supremely challenging scientific aspects, has ensured this topic's high popularity over the preceeding decades. Herein, we report a non-exhaustive account of the current developments within the field of oxidative methane upgrading and summarise the pertaining challenges that have yet to be solved. PMID:22848012

Hammond, Ceri; Conrad, Sabrina; Hermans, Ive

2012-07-29

160

Methionine oxidation and aging.  

PubMed

It is well established that many amino acid residues of proteins are susceptible to oxidation by various forms of reactive oxygen species (ROS), and that oxidatively modified proteins accumulate during aging, oxidative stress, and in a number of age-related diseases. Methionine residues and cysteine residues of proteins are particularly sensitive to oxidation by ROS. However, unlike oxidation of other amino acid residues, the oxidation of these sulfur amino acids is reversible. Oxidation of methionine residues leads to the formation of both R- and S-stereoisomers of methionine sulfoxide (MetO) and most cells contain stereospecific methionine sulfoxide reductases (Msr's) that catalyze the thioredoxin-dependent reduction of MetO residues back to methionine residues. We summarize here results of studies, by many workers, showing that the MetO content of proteins increases with age in a number of different aging models, including replicative senescence and erythrocyte aging, but not in mouse tissues during aging. The change in levels of MetO may reflect alterations in any one or more of many different mechanisms, including (i) an increase in the rate of ROS generation; (ii) a decrease in the antioxidant capacity; (iii) a decrease in proteolytic activities that preferentially degrade oxidized proteins; or (iv) a decrease in the ability to convert MetO residues back to Met residues, due either to a direct loss of Msr enzyme levels or indirectly to a loss in the availability of the reducing equivalents (thioredoxin, thioredoxin reductase, NADPH generation) involved. The importance of Msr activity is highlighted by the fact that aging is associated with a loss of Msr activities in a number of animal tissues, and mutations in mice leading to a decrease in the Msr levels lead to a decrease in the maximum life span, whereas overexpression of Msr leads to a dramatic increase in the maximum life span. PMID:15680221

Stadtman, Earl R; Van Remmen, Holly; Richardson, Arlan; Wehr, Nancy B; Levine, Rodney L

2005-01-17

161

Nitrogen Oxides (GCMP)  

NSDL National Science Digital Library

Nitrogen Oxides: this is a resource in the collection "General Chemistry Multimedia Problems". Two of the most important nitrogen oxides, N2O4 and NO2, are in equilibrium with each other. We are interested in how this equilibrium shifts with temperature. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.

162

Sulfite Oxidation in Plants  

Microsoft Academic Search

Sulfite oxidation in plants was a matter of controversial discussion for a long time and still is not finally understood.\\u000a There is no doubt anymore about the occurrence of sulfite oxidation besides primary sulfate assimilation that takes place\\u000a in the chloroplast. Sulfate is reduced via sulfite to organic sulfide which is essential for the biosynthesis of S-containing\\u000a amino acids and

Robert Hänsch; Ralf R. Mendel

163

ADVANCED OXIDATION PROCESS  

SciTech Connect

The removal of recalcitrant sulfur species, dibenzothiophene and its derivatives, from automotive fuels is an integral component in the development of cleaner burning and more efficient automobile engines. Oxidative desulfurization (ODS) wherein the dibenzothiophene derivative is converted to its corresponding sulfoxide and sulfone is an attractive approach to sulfur removal because the oxidized species are easily extracted or precipitated and filtered from the hydrocarbon phase. Fe-TAML{reg_sign} activators of hydrogen peroxide (TAML is Tetra-Amido-Macrocyclic-Ligand) catalytically convert dibenzothiophene and its derivatives rapidly and effectively at moderate temperatures (50-60 C) and ambient pressure to the corresponding sulfoxides and sulfones. The oxidation process can be performed in both aqueous systems containing alcohols such as methanol, ethanol, or t-butanol, and in a two-phase hydrocarbon/aqueous system containing tert-butanol or acetonitrile. In the biphasic system, essentially complete conversion of the DBT to its oxidized products can be achieved using slightly longer reaction times than in homogeneous solution. Among the key features of the technology are the mild reaction conditions, the very high selectivity where no over oxidation of the sulfur compounds occurs, the near stoichiometric use of hydrogen peroxide, the apparent lack of degradation of sensitive fuel components, and the ease of separation of oxidized products.

Dr. Colin P. Horwitz; Dr. Terrence J. Collins

2003-11-04

164

The reduction and oxidation behaviour of manganese oxides  

Microsoft Academic Search

The reduction of manganese oxides with methane was studied to investigate the suitability of manganese as an oxygen storage compound. Manganese oxides are reduced by CH4 to a lower-valent manganese oxide, producing CO2 and water. Once the manganese oxide is reduced, it can be regenerated, i.e. reoxidised. By integrating this exothermic oxidation cycle with endothermic methane reforming, a new setup

E. R. Stobbe; B. A. de Boer; J. W. Geus

1999-01-01

165

Silver(II) Oxide or Silver(I,III) Oxide?  

ERIC Educational Resources Information Center

|The often called silver peroxide and silver(II) oxide, AgO or Ag[subscript 2]O[subscript 2], is actually a mixed oxidation state silver(I,III) oxide. A thermochemical cycle, with lattice energies calculated within the "volume-based" thermodynamic approach, explain why the silver(I,III) oxide is more stable than the hypothetical silver(II) oxide

Tudela, David

2008-01-01

166

Oxide ion conductivity in doped Ga based perovskite type oxide  

Microsoft Academic Search

Oxide ion conductivity of Ga based perovskite type oxides, LnGaO3, (Ln = Nd, La) and its related oxide, A3Ga2O6 (A = Ba and St) was investigated. Oxide ion transference number is almost 1.0 on Sr3Ga2O6 or Ba3Ga2O6. However, electrical conductivity of these A3Ga2O6 system oxides was lower than log (?Scm?1) = ? 3 due to the low solubility of the

Tatsumi Ishihara; Hideaki Matsuda; Mohamad Azmi bin Bustam; Yusaku Takita

1996-01-01

167

Oxide fiber targets at ISOLDE  

Microsoft Academic Search

Many elements are rapidly released from oxide matrices. Some oxide powder targets show a fast sintering, thus losing their favorable release characteristics. Loosely packed oxide fiber targets are less critical since they may maintain their open structure even when starting to fuse together at some contact points.The experience with various oxide fiber targets (titania, zirconia, ceria and thoria) used in

U. Köster; U. C. Bergmann; D. Carminati; R. Catherall; J. Cederkäll; B. Crepieux; M. Dietrich; K. Elder; V. N. Fedoseyev; L. Fraile; S. Franchoo; H. Fynbo; U. Georg; T. Giles; A. Joinet; O. C. Jonsson; R. Kirchner; Ch. Lau; J. Lettry; H. J. Maier; V. I. Mishin; M. Oinonen; K. Peräjärvi; H. L. Ravn; T. Rinaldi; M. Santana-Leitner; U. Wahl; L. Weissman

2003-01-01

168

Erythropoietin and Oxidative Stress  

PubMed Central

Unmitigated oxidative stress can lead to diminished cellular longevity, accelerated aging, and accumulated toxic effects for an organism. Current investigations further suggest the significant disadvantages that can occur with cellular oxidative stress that can lead to clinical disability in a number of disorders, such as myocardial infarction, dementia, stroke, and diabetes. New therapeutic strategies are therefore sought that can be directed toward ameliorating the toxic effects of oxidative stress. Here we discuss the exciting potential of the growth factor and cytokine erythropoietin for the treatment of diseases such as cardiac ischemia, vascular injury, neurodegeneration, and diabetes through the modulation of cellular oxidative stress. Erythropoietin controls a variety of signal transduction pathways during oxidative stress that can involve Janus-tyrosine kinase 2, protein kinase B, signal transducer and activator of transcription pathways, Wnt proteins, mammalian forkhead transcription factors, caspases, and nuclear factor ?B. Yet, the biological effects of erythropoietin may not always be beneficial and may be poor tolerated in a number of clinical scenarios, necessitating further basic and clinical investigations that emphasize the elucidation of the signal transduction pathways controlled by erythropoietin to direct both successful and safe clinical care.

Maiese, Kenneth; Chong, Zhao Zhong; Hou, Jinling; Shang, Yan Chen

2008-01-01

169

CO Oxidation on Copper Oxide Cluster Ions  

NASA Astrophysics Data System (ADS)

We investigated the reaction of CO and O2 on size-selected copper cluster ions, Cun^+ (n=4--18) and Cun^- (n=4--11), by use of a tandem mass-spectrometer equipped with octopole ion guides. A coadsorbing product, CunO2(CO)^+, was observed in the reaction of CunO2^+ with CO, and it was found that CO adsorbs onto CunO2^+ more efficiently than onto Cun^+ in n >=9. This shows the cooperative coadsorption of O2 and CO. On the other hand, in the reaction of CunO2^- with CO, a reduced product, CunO^-, was obtained instead of the coadsorbing product, CunO2(CO)^-. In particular, Cu5O2^- and Cu9O2^- have relatively high efficiency for the production of CunO^-. This result suggests the production of CO2 by the oxidation of CO on CunO2^-. The DFT calculation indicates that the activation energy in the reaction of Cu5O2(CO)^- -> Cu5O(CO2)^- is only 0.79 eV while that of the corresponding cation is 1.79 eV. The structure of Cun^- is more flexible than that of Cun^+ probably because of its excess electron. It is concluded that the stabilization of the transition state and the decrease of the activation energy make the CO oxidation proceed on CunO2^-.

Ichihashi, Masahiko; Hirabayashi, Shinichi; Kawazoe, Yoshiyuki

2012-02-01

170

Oxidative Tritium Decontamination System  

SciTech Connect

The Princeton Plasma Physics Laboratory, Tritium Systems Group has developed and fabricated an Oxidative Tritium Decontamination System (OTDS), which is designed to reduce tritium surface contamination on various components and items. The system is configured to introduce gaseous ozone into a reaction chamber containing tritiated items that require a reduction in tritium surface contamination. Tritium surface contamination (on components and items in the reaction chamber) is removed by chemically reacting elemental tritium to tritium oxide via oxidation, while purging the reaction chamber effluent to a gas holding tank or negative pressure HVAC system. Implementing specific concentrations of ozone along with catalytic parameters, the system is able to significantly reduce surface tritium contamination on an assortment of expendable and non-expendable items. This paper will present the results of various experimentation involving employment of this system.

Charles A. Gentile; John J. Parker; Gregory L. Guttadora; Lloyd P. Ciebiera

2002-02-11

171

Enhanced mercury oxidation  

SciTech Connect

A new catalyst offers a new way to enhance mercury control from bituminous coal-fired power plants. Hitachi has developed an SCR catalyst which satisfies high Hg{sup 0} oxidation and low SO{sub 2} oxidation requirements under high temperatures (716 to 770 F). This triple action catalysts, TRAC can significantly enhance mercury oxidation and reduce or eliminate the need for additional mercury control measures such as activated carbon injection. After laboratory testing, pilot-scale tests confirmed an activity of 1.4-1.7 times higher than that of conventional SCR catalyst. The new catalyst has been successfully applied in a commercial PRB-fired boiler without the need for halogens to be added to the fuel feed or flue gas. 2 figs.

Gretta, W.J.; Wu, S.; Kikkawa, H. [Hitachi Power Systems America, Basting Ridge, NJ (United States)

2009-06-15

172

Metal Oxides Synthesis  

Microsoft Academic Search

\\u000a Many oxide\\/oxide composite nanocrystals were synthesized in continuous flow SCW processes in short time (e.g., 0.4 s?2 min)\\u000a from metal cations via hydrolysis and subsequent dehydration. Metal particles could be produced by further reduction of the\\u000a metal oxide in SCW. These particles included ferrite magnetic pigments [Fe3O4, MFe2O4 (M = Co, Ni, Zn), NixCo1?xFe2O4, \\u000a \\u000a\\u000a\\u000a\\u000a\\u000a\\u000aBaO\\\\scriptscriptstyle·<\\/font\\u000a>6Fe2 O3{\\\\textrm {BaO}}{\\\\scriptscriptstyle{\\\\bullet}}6{\\\\textrm{Fe}}_{2} {\\\\textrm{O}}_{3}\\u000a ] for recording

Zhen Fang

173

Methanol partial oxidation reformer  

DOEpatents

A partial oxidation reformer comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell.

Ahmed, Shabbir (Bolingbrook, IL); Kumar, Romesh (Naperville, IL); Krumpelt, Michael (Naperville, IL)

1999-01-01

174

Methanol partial oxidation reformer  

DOEpatents

A partial oxidation reformer comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell.

Ahmed, Shabbir (Bolingbrook, IL); Kumar, Romesh (Naperville, IL); Krumpelt, Michael (Naperville, IL)

2001-01-01

175

Low thermal conductivity oxides  

SciTech Connect

Oxides hold great promise as new and improved materials for thermal-barrier coating applications. The rich variety of structures and compositions of the materials in this class, and the ease with which they can be doped, allow the exploration of various mechanisms for lowering thermal conductivity. In this article, we review recent progress in identifying specific oxides with low thermal conductivity from both theoretical and experimental perspectives. We explore the mechanisms of lowering thermal conductivity, such as introducing structural/chemical disorder, increasing material density, increasing the number of atoms in the primitive cell, and exploiting the structural anisotropy. We conclude that further systematic exploration of oxide crystal structures and chemistries are likely to result in even further improved thermal-barrier coatings.

Pan, Wei; Phillpot, Simon R.; Wan, Chunlei; Chernatynskiy, Aleksandr; Qu, Zhixue

2012-01-01

176

Methanol partial oxidation reformer  

DOEpatents

A partial oxidation reformer is described comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell. 7 figs.

Ahmed, S.; Kumar, R.; Krumpelt, M.

1999-08-24

177

Methanol partial oxidation reformer  

DOEpatents

A partial oxidation reformer is described comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell. 7 figs.

Ahmed, S.; Kumar, R.; Krumpelt, M.

1999-08-17

178

Microbial Formaldehyde Oxidation  

SciTech Connect

This project analyzed how cells sense and generate energy from formaldehyde oxidation. Formaldehyde is a toxin that is produced naturally, chemically or by metabolism of a wide variety of methyl-containing compounds. Our goals are to identify how cells sense the presence of this toxic compound and determine how they generate energy and nutrients from the oxidation of formaldehyde. This research capitalizes on the role of the Rhodobacter sphaeroides glutathione dependent formaldehyde dehydrogenase (GSH FDH) in a formaldehyde oxidation pathway that is apparently found in a wide variety of microbes, plants and animals. Thus, our findings illustrate what is required for a large variety of cells to metabolize this toxic compound. A second major focus of our research is to determine how cells sense the presence of this toxic compound and control the expression of gene products required for its detoxification.

Timothy J. Donohue

2004-12-09

179

Tetraalykylammonium polyoxoanionic oxidation catalysts  

DOEpatents

Alkanes are catalytically oxidized in air or oxygen using iron-substituted polyoxoanions (POAs) of the formula: H.sub.e-z ›(n-C.sub.4 H.sub.9).sub.4 N!.sub.z (XM.sub.11 M'O.sub.39).sup.-e The M' (e.g., iron(III)/iron(II)) reduction potential of the POAs is affected by selection of the central atom X and the framework metal M, and by the number of tetrabutyl-ammonium groups. Decreased Fe(III)/Fe(II) reduction potential has been found to correlate to increased oxidation activity.

Ellis, Paul E. (Downingtown, PA); Lyons, James E. (Wallingford, PA); Myers, Jr., Harry K. (Cochranville, PA); Shaikh, Shahid N. (Media, PA)

1998-01-01

180

Biomimetic methane oxidation  

NASA Astrophysics Data System (ADS)

Methane monooxygenase (MMO) is an enzyme found in methanotrophs that catalyses the selective oxidation of methane to methanol. MMO is protein complex one component of which is a binuclear metal center containing oxygenase. We have completed one round of a design/synthesis/evaluation cycle in the development of coordination complexes that mimic the structure/function of the MMO active site. One of these, a binuclear, coordinately-asymmetric copper complex, is capable of oxidizing cyclohexane to a mixture of cyclohexanol and cyclohexanone in the presence of hydrogen peroxide.

Watkins, B. E.; Droege, M. W.; Taylor, R. T.; Satcher, J. H.

1992-06-01

181

Oxide Solar Cells Fabricated Using Zinc Oxide and Plasma-Oxidized Cuprous Oxide  

NASA Astrophysics Data System (ADS)

Oxide heterojunction solar cells composed of an n-type Al-doped ZnO (AZO) thin film on the surfaces of p-type Cu2O films were fabricated. The Cu2O films of about 0.34 to 1.67 ?m thickness were grown by partial oxidation of a Cu sheet using microwave plasma. The AZO film of 400 nm thickness was deposited by magnetron sputtering. Energy conversion efficiencies of 0.12 to 0.30% were obtained in AZO/Cu2O cells under AM1.5 solar illumination.

Chan, Yi-Ming; Wu, Ya-Ting; Jou, Shyankay

2012-12-01

182

Tetraalklylammonium polyoxoanionic oxidation catalysts  

DOEpatents

Alkanes are catalytically oxidized in air or oxygen using iron-substituted polyoxoanions (POAs) of the formula: H{sub e{minus}z}[(n-C{sub 4}H{sub 9}){sub 4}N]{sub z}(XM{sub 11}M{prime}O{sub 39}){sup {minus}e}. The M{prime} (e.g., iron(III)/iron(II)) reduction potential of the POAs is affected by selection of the central atom X and the framework metal M, and by the number of tetrabutyl-ammonium groups. Decreased Fe(III)/Fe(II) reduction potential has been found to correlate to increased oxidation activity.

Ellis, P.E.; Lyons, J.E.; Myers, H.K. Jr.; Shaikh, S.N.

1998-10-06

183

Uranium Oxidation: Characterization of Oxides Formed by Reaction with Water.  

National Technical Information Service (NTIS)

Three different uranium oxide samples have been characterized with respect to the different preparation techniques. Results show that the water reaction with uranium metal occurs cyclically forming laminar layers of oxide which spall off due to the strain...

E. L. Fuller J. B. Condon M. H. Eager N. R. Smyrl

1983-01-01

184

78 FR 14591 - Persulfates From China; Correction to Notice of institution  

Federal Register 2010, 2011, 2012, 2013

...obtain information on this matter by contacting the Commission's TDD terminal on 202-205- 1810. Persons with mobility impairments who will need special assistance in gaining access to the Commission should contact the Office of the...

2013-03-06

185

Influence of persulfate ions on the removal of phenol in aqueous solution using electron beam irradiation  

Microsoft Academic Search

The removal of phenol (Co=100?M) during electron beam irradiation was studied in pure water and in the presence of HCO3? and Br? ions. It was found that the introduction of S2O82? ions (1mM), by generating SO4? radicals increases the radiation yield of phenol removal. 90% removal of phenol was obtained with radiation doses 600 and 1200Gy with and without S2O82?

Sahidou O. B. Boukari; Fabien Pellizzari; Nathalie Karpel Vel Leitner

2011-01-01

186

Hysteresis in gadolinium oxide metal-oxide-semiconductor capacitors  

NASA Astrophysics Data System (ADS)

This investigation explores how oxidation affects the gadolinium oxide capacitor and the corresponding Gd2O3 hysteresis phenomenon. The current-voltage varied with Gd2O3 thickness and a charged capacitance voltage (C-V) curve with a left shift is also observed in experimental results. The breakdown voltages rise with increasing oxidation time, while the corresponding C-V hysteresis gaps decrease with increasing oxidation time.

Hsieh, Li-Zen; Ko, Hong-Hsi; Kuei, Ping-Yu; Chang, Liann-Be; Jeng, Ming-Jer

2005-10-01

187

Regularities of catalytic oxidation of carbon by nitrous oxide  

SciTech Connect

The main regularities of the catalytic oxidation of various carbon materials by nitrous oxide are studied. The compounds of a series of alkaline and alkaline-earth metals are found to be effective catalysts for this process, which decrease the temperature of the beginning of carbon oxidation by {approximately} 150 - 200{degrees}C. The activity of alkaline metals is enhanced with increasing metal atomic mass. The rate of the carbon oxidation depends on the nature of a carbon material.

Babenko, V.S.; Buyanov, R.A. [Boreskov Institute of Catalysis, Novosibirsk (Russian Federation)

1995-07-01

188

Highly oxidized superconductors  

DOEpatents

Novel superconducting materials in the form of compounds, structures or phases are formed by performing otherwise known syntheses in a highly oxidizing atmosphere rather than that created by molecular oxygen at atmospheric pressure or below. This leads to the successful synthesis of novel superconducting compounds which are thermodynamically stable at the conditions under which they are formed.

Morris, Donald E. (Kensington, CA)

1994-01-01

189

Monoliths in catalytic oxidation  

Microsoft Academic Search

Catalytic combustion is useful to avoid emission of nitrogen oxides, to combust fuel gas of different calorific levels, and to combust low contents of badly smelling or hazardous gaseous compounds. After dealing with some characteristics of catalytic combustion it is argued that catalytic combustion to a final temperature lower than about 800°C calls for a rapid transport of thermal energy

John W. Geus; Joep C. van Giezen

1999-01-01

190

Doped zinc oxide microspheres  

DOEpatents

A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel.

Arnold, Jr., Wesley D. (Oak Ridge, TN); Bond, Walter D. (Knoxville, TN); Lauf, Robert J. (Oak Ridge, TN)

1993-01-01

191

Doped zinc oxide microspheres  

DOEpatents

A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel. 4 figures.

Arnold, W.D. Jr.; Bond, W.D.; Lauf, R.J.

1993-12-14

192

Green Catalytic Oxidations.  

National Technical Information Service (NTIS)

The search for new, clean reactions that can compete with established chemical processes is one of the main challenges of today's chemistry. Recent developments in this area - with a focus on oxidation chemistry - are described in chapter 1. In chapter 2 ...

G. J. Ten Brink

2001-01-01

193

Plutonium oxide dissolution.  

National Technical Information Service (NTIS)

Several processing options for dissolving plutonium oxide (PuO(sub 2)) from high-fired materials have been studied. The scoping studies performed on these options were focused on PuO(sub 2) typically generated by burning plutonium metal and PuO(sub 2) pro...

J. H. Gray

1992-01-01

194

Partial oxidation system  

Microsoft Academic Search

A partial oxidation control system for continuously producing synthesis gas, fuel gas or reducing gas in which one process fuel is replaced by a different fuel without shutting down or depressurizing the gas generator. Suitable burners for introducing the feedstreams into the gas generator comprise a central conduit means radially spaced from a concentric coaxial outer conduit having a downstream

C. P. Marion; A. Brent; E. T. Child; W. B. Crouch; B. Reynolds; G. N. Richter

1984-01-01

195

Oxidative conversion of methane  

Microsoft Academic Search

The data on various aspects of oxidative conversion of methane published in 1998-2004 are considered. Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors Title Abstract Text Return: Query Results Return items starting with number Query Form Database: Astronomy Physics arXiv e-prints

Vladimir S. Arutyunov; Oleg V. Krylov

2005-01-01

196

Inorganic Halogen Oxidizers.  

National Technical Information Service (NTIS)

The new oxidizer oxychlorine trifluoride, ClF3O, was prepared by the fluorination of CsF complexes of both ClO2 and ClNO3. Physical properties were determined. The molar heat of vaporization is 7.7 kcal. ClFO3 was found to be thermally stable to 284 C, al...

D. Pilipovich C. B. Lindahl H. F. Bauer C. J. Schack

1965-01-01

197

Controlling Nitrogen Oxides.  

National Technical Information Service (NTIS)

Recent research indicates that nitrogen oxides (NOx) could be one of the most troublesome air pollutants of the 1980's. More than 20 million metric tons of NOx are annually polluting our air as a result of the widespread combustion of fossil fuels in powe...

A. Hastings M. Schaefer

1980-01-01

198

Electrochemical oxidation of chlorophenols  

Microsoft Academic Search

Electrochemical 2-chlorophenol and 2,6-dichlorophenol removal from aqueous solutions using porous carbon felt anodes was investigated. Operating variables including current input, ratio between electrode and solution volumes, and initial pollutant concentration were considered in order to determine their influence on the faradic efficiency of the process. The byproducts of the oxidation reaction were identified, and their concentration was determined during the

Anna M. Polcaro; Simona Palmas

1997-01-01

199

CONTROLLING NITROGEN OXIDES  

EPA Science Inventory

Recent research indicates that nitrogen oxides (NOx) could be one of the most troublesome air pollutants of the 1980's. More than 20 million metric tons of NOx are annually polluting our air as a result of the widespread combustion of fossil fuels in power plants, industrial boil...

200

Proton-Conducting Oxides  

NASA Astrophysics Data System (ADS)

The structural and chemical parameters determining the formation and mobility of protonic defects in oxides are discussed, and the paramount role of high-molar volume, coordination numbers, and symmetry are emphasized. Symmetry also relates to the structural and chemical matching of the acceptor dopant. Y-doped BaZrO3-based oxides are demonstrated to combine high stability with high proton conductivity that exceeds the conductivity of the best oxide ion conductors at temperatures below about 700oC. The unfavorably high grain boundary impedances and brittleness of ceramics have been reduced by forming solid solutions with small amounts of BaCeO3, and an initial fuel cell test has demonstrated that proton-conducting electrolytes based on Y-doped BaZrO3 provide alternatives for separator materials in solid oxide fuel cells (SOFCs). These materials have the potential to operate at lower temperatures compared with those of conventional SOFCs, and the appearance of chemical water diffusion across the electrolyte at typical operation temperatures (T = 500-800oC) allows the use of dry methane as a fuel.

Kreuer, K. D.

2003-08-01

201

CONTROLLING SULFUR OXIDES  

EPA Science Inventory

This Research Summary describes EPA's program to develop new and improve existing technologies for sulfur oxides control. As we increasingly turn to coal as the primary utility and industrial fuel, while trying to deal with the problems of acid precipitation, visibility degradati...

202

Solid-state oxidation of aniline hydrochloride with various oxidants  

Microsoft Academic Search

Aniline hydrochloride was oxidized in the solid state with three different oxidants: ammonium peroxydisulfate, iron(III) chloride, and silver nitrate. Polyaniline salt was obtained after a few hours when ammonium peroxydisulfate was used as an oxidant. The polymerization of aniline hydrochloride with silver nitrate leads to polyaniline only after several days; in the case of iron(III) chloride, aniline oligomers were obtained.

Ivana Šed?nkovį; Elena N. Konyushenko; Jaroslav Stejskal; Miroslava Trchovį; Jan Prokeš

2011-01-01

203

Iridium oxide and palladium modified nitric oxide microsensor  

Microsoft Academic Search

An electrochemical microsensor, constructed by chemical modification of Nafion, poly(vinyl pyridine) (PVP), palladium and iridium oxide onto a platinum microelectrode, has been developed for the determination of nitric oxide (NO). This microsensor exhibits excellent catalytic activity toward NO oxidation, which is confirmed by differential pulse voltammetry. Cyclic voltammetry and differential pulse amperometry are also performed to measure NO. The catalytic

Yuezhong Xian; Wenliang Sun; Jian Xue; Min Luo; Litong Jin

1999-01-01

204

Oxidative stress, anti-oxidant therapies and chronic kidney disease.  

PubMed

Chronic kidney disease (CKD) is a common and serious problem that adversely affects human health, limits longevity and increases costs to health-care systems worldwide. Its increasing incidence cannot be fully explained by traditional risk factors. Oxidative stress is prevalent in CKD patients and is considered to be an important pathogenic mechanism. Oxidative stress develops from an imbalance between free radical production often increased through dysfunctional mitochondria formed with increasing age, type 2 diabetes mellitus, inflammation, and reduced anti-oxidant defences. Perturbations in cellular oxidant handling influence downstream cellular signalling and, in the kidney, promote renal cell apoptosis and senescence, decreased regenerative ability of cells, and fibrosis. These factors have a stochastic deleterious effect on kidney function. The majority of studies investigating anti-oxidant treatments in CKD patients show a reduction in oxidative stress and many show improved renal function. Despite heterogeneity in the oxidative stress levels in the CKD population, there has been little effort to measure patient oxidative stress levels before the use of any anti-oxidants therapies to optimize outcome. This review describes the development of oxidative stress, how it can be measured, the involvement of mitochondrial dysfunction and the molecular pathways that are altered, the role of oxidative stress in CKD pathogenesis and an update on the amelioration of CKD using anti-oxidant therapies. PMID:22288610

Small, David M; Coombes, Jeff S; Bennett, Nigel; Johnson, David W; Gobe, Glenda C

2012-05-01

205

Alkali Oxide-Tantalum, Niobium and Antimony Oxide Ionic Conductors.  

National Technical Information Service (NTIS)

The phase equilibrium relations of four systems were investigated in detail. These consisted of sodium and potassium antimonates with antimony oxide and tantalum and niobium oxide with rubidium oxide as far as the ratio 4Rb2O:llB2O5 (B=Nb, Ta). The ternar...

R. S. Roth W. S. Brower H. S. Parker D. B. Minor J. L. Waring

1975-01-01

206

Fabrication of titanium oxide nanotube arrays by anodic oxidation  

Microsoft Academic Search

The formation of titanium oxide nanotube arrays on titanium substrates was investigated in HF electrolytes. Under optimized electrolyte and oxidation conditions, well-ordered nanotubes of titania were fabricated. Topologies of the anodized titanium change remarkably along with the changing of applied voltages, electrolyte concentration and oxidation time. Electrochemical determination and scanning electron microscope indicate the nanotubes are formed due to the

Jianling Zhao; Xiaohui Wang; Renzheng Chen; Longtu Li

2005-01-01

207

Active oxide nanophotonics  

NASA Astrophysics Data System (ADS)

Materials that can be manipulated electrically or mechanically to induce a change in their intrinsic properties are highly relevant when suitably integrated with current technologies. These "active" materials, such as oxide-based ferroelectrics or materials with easily accessible changes of phase, find extensive use as mechanical resonators, solid-state memories, and optical modulators. Barium titanate, a tetragonal ferroelectric at room temperature, is a prime example of a material both mechanically and optically active. This thesis deals primarily with the deposition of active, oxide-based materials and their integration into device structures where either the mechanical or optical properties are exploited. The technologically interesting paradigms within which these active oxide materials have been investigated are microelectromechanical systems, plasmonics, and metamaterials. Microelectromechanical systems are devices that have been micromachined and rely on an applied voltage to induce a mechanical response. Mechanically active materials, such as piezoelectrics or ferroelectrics, can increase the response of these devices. Plasmonics deals with electromagnetic waves resonantly coupled into free electron oscillations at a metal-dielectric interface or metal nanoparticle. Coupling to these resonant modes allows surface plasmon polaritons to propagate along the metal with a nonlinear dispersion. Metamaterials are ordered, subwavelength, metal inclusions in a dielectric, which respond collectively to electromagnetic radiation. This response can yield a material permittivity or permeability not found in nature. The optical properties of metamaterials lead to effects such as negative index response and super lensing, and can be used to design optical cloaking structures. Here, devices utilizing these effects are investigated with an eye toward tuning or switching their resonant response using optically active oxide thin films. This manuscript follows the evolution of active oxide thin films from deposition, through design of plasmonic devices and active metamaterials, finite difference modeling of these structures, and finally experimental validation. First, deposition and material integration techniques for oxide-based thin films will be discussed. The role of molecular beam epitaxy, pulsed laser deposition, and ion beam assisted deposition as material growth techniques are investigated. Development of a multitude of oxide materials using these techniques including barium titanate, strontium ruthenate, vanadium oxide, and magnesium oxide will be covered. The following two sections deal with the mechanical and optical properties of barium titanate thin films as they are studied and utilized to design and fabricate active devices. Films were characterized mechanically, using nanoindentation and piezoresponse force microscopy, and optically with variable angle spectroscopic ellipsometry. The subsequent section deals with the design, fabrication, and experimental validation of an active optical device based on surface plasmon polariton wavevector modulation via electrooptic modulation of a barium titanate thin film. Interferometers based on pairs of parallel slits fabricated in silver films on barium titanate are used to investigate optical modulation due to both domain switching and the electrooptic effect. Finally, active metamaterials are discussed through the investigation of a new material, vanadium oxide, as it is deposited and characterized, and the results used to design and fabricate active, split-ring resonator metamaterial structures.

Dicken, Matthew J.

208

Oxygen sensitive, refractory oxide composition  

DOEpatents

Oxide compositions containing niobium pentoxide and an oxide selected from the group consisting of hafnia, titania, and zirconia have electrical conductivity characteristics which vary greatly depending on the oxygen content.

Holcombe, Jr., Cressie E. (Oak Ridge, TN); Smith, Douglas D. (Knoxville, TN)

1976-01-01

209

Heteorocyclic Synthesis by Persulphate Oxidation.  

National Technical Information Service (NTIS)

Persulphate oxidation of N-phenyl-C-(o-carboxymethoxyphenyl) nitrone gave azoxybenzene as a result of hydrolysis of the nitrone function to give phenylhydroxylamine which was then oxidized. o-Phenylazobenzoic acid, its anilide, and o-phenylazoxybenzanilid...

R. H. Thomson

1972-01-01

210

ADVANCED OXIDATION PROCESS  

SciTech Connect

The design of new, high efficiency and cleaner burning engines is strongly coupled with the removal of recalcitrant sulfur species, dibenzothiophene and its derivatives, from fuels. Oxidative desulfurization (ODS) wherein these dibenzothiophene derivatives are oxidized to their corresponding sulfoxides and sulfones is an approach that has gained significant attention. Fe-TAML{reg_sign} activators of hydrogen peroxide (TAML is Tetra-Amido-Macrocyclic-Ligand) convert in a catalytic process dibenzothiophene and its derivatives to the corresponding sulfoxides and sulfones rapidly at moderate temperatures (60 C) and ambient pressure. The reaction can be performed in both an aqueous system containing an alcohol (methanol, ethanol, or t-butanol) to solubilize the DBT and in a two-phase hydrocarbon/aqueous system where the alcohol is present in both phases and facilitates the oxidation. Under a consistent set of conditions using the FeBF{sub 2} TAML activator, the degree of conversion was found to be t-butanol > methanol > ethanol. In the cases of methanol and ethanol, both the sulfoxide and sulfone were observed while for t-butanol only the sulfone was detected. In the two-phase system, the alcohol may function as an inverse phase transfer agent. The oxidation was carried out using two different TAML activators. In homogeneous solution, approximately 90% oxidation of the DBT could be achieved using the prototype TAML activator, FeB*, by sonicating the solution at near room temperature. In bi-phasic systems conversions as high as 50% were achieved using the FeB* TAML activator and hydrogen peroxide at 100 C. The sonication method yielded only {approx}6% conversion but this may have been due to mixing.

Colin P. Horwitz; Terrence J. Collins

2003-10-22

211

REVIEW OF PLUTONIUM OXIDATION LITERATURE  

SciTech Connect

A brief review of plutonium oxidation literature was conducted. The purpose of the review was to ascertain the effect of oxidation conditions on oxide morphology to support the design and operation of the PDCF direct metal oxidation (DMO) furnace. The interest in the review was due to a new furnace design that resulted in oxide characteristics that are different than those of the original furnace. Very little of the published literature is directly relevant to the DMO furnace operation, which makes assimilation of the literature data with operating conditions and data a convoluted task. The oxidation behavior can be distilled into three regimes, a low temperature regime (RT to 350 C) with a relatively slow oxidation rate that is influenced by moisture, a moderate temperature regime (350-450 C) that is temperature dependent and relies on more or less conventional oxidation growth of a partially protective oxide scale, and high temperature oxidation (> 500 C) where the metal autocatalytically combusts and oxidizes. The particle sizes obtained from these three regimes vary with the finest being from the lowest temperature. It is surmised that the slow growth rate permits significant stress levels to be achieved that help break up the oxides. The intermediate temperatures result in a fairly compact scale that is partially protective and that grows to critical thickness prior to fracturing. The growth rate in this regime may be parabolic or paralinear, depending on the oxidation time and consequently the oxide thickness. The high temperature oxidation is invariant in quiescent or nearly quiescent conditions due to gas blanketing while it accelerates with temperature under flowing conditions. The oxide morphology will generally consist of fine particles (<15 {micro}m), moderately sized particles (15 < x < 250 {micro}m) and large particles (> 250 {micro}m). The particle size ratio is expected to be < 5%, 25%, and 70% for fine, medium and large particles, respectively, for metal temperatures in the 500-600 C range.

Korinko, P.

2009-11-12

212

Electrochemical Oxidation of 8-Oxoguanine  

Microsoft Academic Search

Abstract Electrochemical oxidation of DNA can occur at each of the four bases and guanine is the one that can suffer the easiest oxidative damage. The occurrence of the guanine oxidation product, 8-oxoguanine, as a consequence of DNA damage caused by DNA oxidation causes important mutagenic,lesions and hence it is very important to develop reliable methods,for its quantification. Electrochemical study

A. M. Oliveira Brett; J. A. P. Piedade; S. H. P. Serrano

2000-01-01

213

Cold Chemical Oxidation of Proteins  

PubMed Central

Various methods of protein footprinting use hydrogen peroxide as oxidant. Its removal by various solid-phase desalting methods, catalase treatment, or freeze-drying after the footprinting is critical to insure no uncontrolled oxidation. Although catalase treatment removes hydrogen peroxide with little loss of protein or additional protein oxidation, we discovered that freeze-drying or freezing of the protein in peroxide solution does lead to protein oxidation. Interestingly, the oxidation is not a result of freeze or thaw processes but depends on the temperature and length of time for incubation. After 2 h, apomyoglobin undergoes nearly complete single oxidation at ?80 °C and double oxidation at ?15 °C. The oxidation extents are in addition to the number of methionine residues. Minimal oxidation is observed at 4 °C and 22 °C compared to oxidation at ?80 °C or ?20 °C. The concentration of hydrogen peroxide is critical; 75 mM (0.2%) is required to oxidize > 50% of the protein at ?15 °C and 100-mM (0.3%) at ?80 °C. In addition to Met, ~ 5% of the tryptophan and tyrosine residues are oxidized as well as lower amounts of His and Phe. Oxidation of Val 68 and Val 17 (a buried residue) also occurs, with the oxidation of Val 17 likely occurring by electron transfer from one of two of the oxidized aromatic residues contacting Val 17. We describe here the need to remove the hydrogen peroxide prior to cold storage of proteins, and we also report some preliminary results pertaining to the mechanism of cold, solid-state oxidation.

Hambly, David M.; Gross, Michael L.

2010-01-01

214

Tailoring oxidation degrees of graphene oxide by simple chemical reactions  

SciTech Connect

High quality graphene oxide (GO) with controllable degrees of oxidation was synthesized by simple chemical reactions inspired by approaches to unzip single wall carbon nanotubes using strong oxidizing agents. As compared to the conventional Hummers method, these reactions are less exo-therm involved without emission of toxic gases. The structural characteristics of the synthesized GO with various oxidation degrees were evaluated by x-ray diffraction, x-ray photoelectron spectroscopy, Raman spectroscopy, thermal gravimetric analysis, and UV-vis-IR spectroscopy. GO with tailored degrees of oxidation displays tunable optoelectronic properties and may have a significant impact on developing graphene- or GO-based platforms for various technological applications.

Wang Gongkai [Key Laboratory for Anisotropy and Texture of Materials of Ministry of Education, Northeastern University, Shenyang, Liaoning 110004 (China); Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Sun Xiang; Lian Jie [Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Liu Changsheng [Key Laboratory for Anisotropy and Texture of Materials of Ministry of Education, Northeastern University, Shenyang, Liaoning 110004 (China)

2011-08-01

215

Neurodegenerative diseases and oxidative stress  

Microsoft Academic Search

Oxidative stress has been implicated in the progression of Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis. Oxygen is vital for life but is also potentially dangerous, and a complex system of checks and balances exists for utilizing this essential element. Oxidative stress is the result of an imbalance in pro-oxidant\\/antioxidant homeostasis that leads to the generation of toxic reactive

Kevin J. Barnham; Colin L. Masters; Ashley I. Bush

2004-01-01

216

Oxidative stress in brain aging  

Microsoft Academic Search

Age has a powerful effect on enhanced susceptibility to neurodegenerative diseases, including susceptibility to stroke and cognitive impairment (CI) even in optimally healthy individuals. We critically evaluated the notion that oxidative stress increases in aging brain. Rigorous studies show logarithmic age-dependent increases in oxidized proteins and oxidized DNA lesions. Decreased activity of antioxidant protective enzymes does not account for the

Robert A Floyd; Kenneth Hensley

2002-01-01

217

Radiation Tolerance of Complex Oxides  

Microsoft Academic Search

The radiation performance of a variety of complex oxides is predicted on the basis of a material's propensity to accommodate lattice point defects. The calculations indicate that a particular class of oxides possessing the fluorite crystal structure should accept radiation-induced defects into their lattices far more readily than a structurally similar class of oxides based on the pyrochlore crystal structure.

K. E. Sickafus; L. Minervini; R. W. Grimes; J. A. Valdez; M. Ishimaru; F. Li; K. J. McClellan; T. Hartmann

2000-01-01

218

The anaerobic oxidation of ammonium  

Microsoft Academic Search

From recent research it has become clear that at least two different possibilities for anaerobic ammonium oxidation exist in nature. `Aerobic' ammonium oxidizers like Nitrosomonas eutropha were observed to reduce nitrite or nitrogen dioxide with hydroxylamine or ammonium as electron donor under anoxic conditions. The maximum rate for anaerobic ammonium oxidation was about 2 nmol NH+4 min?1 (mg protein)?1 using

Mike S. M Jetten; Marc Strous; Katinka T van de Pas-Schoonen; Jos Schalk; Udo G. J. M van Dongen; Astrid A van de Graaf; Susanne Logemann; Gerard Muyzer; Mark C. M van Loosdrecht; J. Gijs Kuenen

1998-01-01

219

Oxidative Degradation of Phosphate Esters  

Microsoft Academic Search

A thin film oxidation (microoxidation) test has been developed to simulate severe liquid phase oxidation in typical lubrication systems. Tributyl phosphate (TBP), tricresyl phosphate (TCP), trixylyl phosphate (TXP) and t-butylphenyl diphenyl phosphate (TBB) have been evaluated and compared. At low rates, oxidation is not limited by oxygen diffusion at the air-liquid interface. Gel permeation chromatography (GPC) has been adapted to

L. Cho; E. E. Klaus

1981-01-01

220

Selective catalytic oxidation of acetonitrile  

Microsoft Academic Search

It has been discovered that acetonitrile can be selectively oxidized in the vapor phase to glycolonitrile (hydroxyacetonitrile) or, in the presence of water, to glycolamide (hydroxyacetamide) using vanadium oxide catalysts. Partial reduction of the catalysts is required to obtain optimum selectivities to the desired partial oxidation products. Crystalline VāOāā present in active catalysts is apparently necessary for activation of acetonitrile

J. F. Brazdil; R. G. Teller; W. A. Marritt; L. C. Glaeser; A. M. Ebner

1986-01-01

221

Oxidative DNA Damage and Carcinogenesis  

Microsoft Academic Search

Carcinogenesis follows multi-step processes involving both genetic alteration and increased cell proliferation. Oxidative stress can occur via overproduction of reactive oxygen and nitrogen species through either endogenous or exogenous insults. Oxidative stress is always associated with inflammation, radiation, reperfusion, and iron overload. Epidemiological observations have shown that oxidative stress is one of the major pathologic mechanisms for cancer, the top-ranked

Li Jiang; Shinya Toyokuni

2011-01-01

222

Clean Metal Oxide Semiconductor Systems  

Microsoft Academic Search

Aspects of sodium contamination of metal-oxide-silicon (MOS) systems associated with silicon surface preparation, the oxidation plenum, and post-oxidation procedures, including contact application, are discussed. The validity of neutron activation analysis to determine sodium distributions in MOS samples is established. Refractory materials for furnace construction are examined and shown to contain as much as 1 - 5 percent sodium or potasium.

H. G. Carlson; C. R. Fuller; D. E. Meyer; J. R. Osborne; V. Harrap; G. A. Brown

1966-01-01

223

Lipid oxidation in food emulsions  

Microsoft Academic Search

Lipid oxidation is a major cause of quality deterioration in food emulsions. The design of foods with improved quality depends on a better understanding of the physicochemical mechanisms of lipid oxidation in these systems. The oxidation of emulsified lipids differs from that of bulk lipids, because of the presence of the droplet membrane, the interactions between the ingredients, and the

John N. Coupland; D. Julian McClements

1996-01-01

224

Enzymes of respiratory iron oxidation  

Microsoft Academic Search

This report focuses on the progress made in three areas of research concerned with enzymes involved in respiratory iron oxidation. The three areas are as follows: development of an improved procedure for the routine large scale culture of iron oxidizing chemolithotrophs based on the in-situ electrolysis of the soluble iron in the growth medium; to perform iron oxidation kinetic studies

Blake; R. II

1991-01-01

225

Electrochemical oxidation of chlorinated phenols  

Microsoft Academic Search

Electrochemical oxidation has been proposed as a remediation method for chlorinated phenols but is hampered by anode fouling. In this work the authors explore the mechanism of anode fouling by chlorinated phenols, compare structure vs reactivity for phenols differing in the extent of chlorination, and relate the efficiency of oxidation to the mechanism of oxidation at different electrode types. Linear

James D. Rodgers; Wojciech Jedral; Nigel J. Bunce

1999-01-01

226

High altitude and oxidative stress  

Microsoft Academic Search

Exposure to high altitude, which is associated with decreased oxygen pressure, could result in oxidative\\/reductive stress, enhanced generation of reactive oxygen and nitrogen species (RONS), and related oxidative damage to lipids, proteins, and DNA. The severity of oxidative challenge is related to the degree of altitude. A wide range of RONS generating systems are activated during exposure to high altitude,

Agoston Dosek; Hideko Ohno; Zoltan Acs; Albert W. Taylor; Zsolt Radak

2007-01-01

227

Catalytic reduction of nitrogen oxides  

Microsoft Academic Search

This patent describes a method for catalytically reducing one or more nitrogen oxides from a gaseous stream containing one or more nitrogen oxides and optionally one or more sulfur oxides. It comprises contacting the gases stream and ammonia with a microporous molecular sieve composition deleted from a zeolitic or silica molecular sieve or mixtures thereof at effective reduction conditions in

M. T. Staniulis; A. P. Risch; J. G. Vassilakill; D. F. Best

1989-01-01

228

Model catalytic oxidation studies using supported monometallic and heterobimetallic oxides  

SciTech Connect

This research program is directed toward a more fundamental understanding of the effects of catalyst composition and structure on the catalytic properties of metal oxides. Metal oxide catalysts play an important role in many reactions bearing on the chemical aspects of energy processes. Metal oxides are the catalysts for water-gas shift reactions, methanol and higher alcohol synthesis, isosynthesis, selective catalytic reduction of nitric oxides, and oxidation of hydrocarbons. A key limitation to developing insight into how oxides function in catalytic reactions is in not having precise information of the surface composition under reaction conditions. To address this problem we have prepared oxide systems that can be used to study cation-cation effects and the role of bridging (-O-) and/or terminal (=O) surface oxygen anion ligands in a systematic fashion. Since many oxide catalyst systems involve mixtures of oxides, we selected a model system that would permit us to examine the role of each cation separately and in pairwise combinations. Organometallic molybdenum and tungsten complexes were proposed for use, to prepare model systems consisting of isolated monomeric cations, isolated monometallic dimers and isolated bimetallic dimers supported on silica and alumina. The monometallic and bimetallic dimers were to be used as models of more complex mixed- oxide catalysts. Our current program was to develop the systems and use them in model oxidation reactions.

Ekerdt, J.G.

1992-02-03

229

Hydroxylamine oxidation and subsequent nitrous oxide production by the heterotrophic ammonia oxidizer Alcaligenes faecalis  

Microsoft Academic Search

Nitrous oxide (N2O), a greenhouse gas, is emitted during autotrophic and heterotrophic ammonia oxidation. This emission may result from either\\u000a coupling to aerobic denitrification, or it may be formed in the oxidation of hydroxylamine (NH2OH) to nitrite (NO2\\u000a ?). Therefore, the N2O production during NH2OH oxidation was studied with Alcaligenes faecalis strain TUD. Continuous cultures of A. faecalis showed increased

S. Otte; J. Schalk; J. G. Kuenen; M. S. M. Jetten

1999-01-01

230

Rupture of an oxide blister  

SciTech Connect

Expressions have been derived which describe the critical stress and pressure necessary to rupture oxide blisters which form on aluminum during the growth of corrosion pits. These expressions have been derived and evaluated for radial cracks in the oxide blister. The critical stress and corresponding pressure for rupture decrease with increasing blister radius and decrease with increasing crack length. The critical stress is independent of the ratio of oxide film thickness to blister radius, whereas the rupture pressure increases with this ratio. The critical stress is independent of Poisson`s ratio for the oxide film whereas the rupture pressure is weakly dependent on Poisson`s ratio for the oxide film.

Ryan, R.L.; McCafferty, E. [Naval Research Lab., Washington, DC (United States)

1995-08-01

231

Oxidation of plutonium dioxide.  

PubMed

The physics and chemistry of the actinide elements form the scientific basis for rational handling of nuclear materials. In recent experiments, most unexpectedly, plutonium dioxide has been found to react with water to form higher oxides up to PuO(2.27), whereas PuO(2) had always been thought to be the highest stable oxide of plutonium. We perform a theoretical analysis of this complicated situation on the basis of total energies calculated within density functional theory combined with well-established thermodynamic data. The reactions of PuO(2) with either O(2) or H(2)O to form PuO(2+delta) are calculated to be endothermic: that is, in order to occur they require a supply of energy. However, our calculations show that PuO(2+delta) can be formed, as an intermediate product, by reactions with the products of radiolysis of water, such as H(2)O(2). PMID:15034561

Korzhavyi, Pavel A; Vitos, Levente; Andersson, David A; Johansson, Börje

2004-03-14

232

Oxidation resistant copper  

NASA Astrophysics Data System (ADS)

Oxidation resistant particles composed of copper and at least one metal having a valence of +2 or +3 and having an intermediate lattice energy for the metal in its hydroxide form are presented. The metal is selected from nickel, cobalt, iron, manganese, cadmium, zinc, tin, magnesium, calcium and chromium. In one embodiment, the phases of copper and at least one metal in the particles are separate and the concentration of the metal is greater near the surface of the particles than inwardly thereof. Process for making the oxidation resistant copper particles includes the steps of dissolving a copper salt and a salt of at least one of the metals in a suitable solvent or diluent; forming primary particles of copper and at least one metal in basic form by mixing a base and the salt solution; separating, washing and drying the primary particles; reducing the primary particles to metallic form; and heat treating the particles in metallic form at an elevated temperature.

Edelstein, Alan S.; Kaatz, Forrest H.; Harris, Vincent G.

1993-11-01

233

Oxidative protein folding  

PubMed Central

During seed development, endosperm cells of highly productive cereals, including rice, synthesize disulfide-rich proteins in large amounts and deposit them into storage organelles. Disulfide bond formation involves electron transfer and generates H2O2 as a by-product. To ensure proper development and maturation of seeds, the endosperm cells must supply large amounts of oxidizing equivalents to dithiols in nascent proteins in a controlled manner. This review compares multiple oxidative protein folding systems in yeast, cultured human cells, and rice endosperm. We discuss possible roles of ERO1, other sulfhydryl oxidases, and the protein disulfide isomerase family in the formation of disulfide bonds in storage proteins and the development of protein bodies. Rice prolamins, encoded by a multigene family, are divided into Cys-rich and Cys-depleted subgroups. We discuss the potential importance of disulfide bond formation in the evolution of the prolamin family in japonica rice.

Onda, Yayoi

2011-01-01

234

Selective oxidation using gold.  

PubMed

This critical review covers the recent development of the catalytic properties of gold in the selective oxidation of organic compounds, highlighting the exciting contribution to the art of catalysis. The unique, outstanding properties of nanometre-scale particles of gold, a biocompatible non-toxic metal, have allowed the development of a new generation of stable and selective catalysts for the conversion of many organic feedstocks to valuable chemicals. A critical discussion of the results of different research groups is presented along with attempts to correlate the catalytic properties with catalyst morphology in non-equivalent series of experiments. Particular emphasis has been given to the international efforts towards optimised synthesis of products of industrial appeal such as propylene oxide, vinyl acetate monomer, cyclohexanol/cyclohexanone, gluconic acid and glyceric acid (168 references). PMID:18762847

Della Pina, Cristina; Falletta, Ermelinda; Prati, Laura; Rossi, Michele

2008-07-14

235

Demystified ... Nitric oxide  

PubMed Central

The discovery of nitric oxide (NO) demonstrated that cells could communicate via the manufacture and local diffusion of an unstable lipid soluble molecule. Since the original demonstration of the vascular relaxant properties of endothelium derived NO, this fascinating molecule has been shown to have multiple, complex roles within many biological systems. This review cannot hope to cover all of the recent advances in NO biology, but seeks to place the discovery of NO in its historical context, and show how far our understanding has come in the past 20 years. The role of NO in mitochondrial respiration, and consequently in oxidative stress, is described in detail because these processes probably underline the importance of NO in the development of disease.

Stuart-Smith, K

2002-01-01

236

Partial oxidation apparatus  

SciTech Connect

An apparatus is described for the simultaneous partial oxidation of a primary fuel stream comprising a high metals or ash containing liquid hydrocarbonaceous fuel or a slurry of solid carbonaceous fuel and a secondary fuel stream to produce a raw gas stream comprising: a vertical cylindrically shaped steel pressure vessel with a coaxial inlet port in the upper end of the vessel and a coaxial outlet port in the lower end of the vessel; a coaxial vertically disposed first gasification burner mounted in the upper inlet port for discharging reactant feedstreams directly into a first vertical coaxial free-flow refractory lined reaction chamber where partial oxidation of the fuel feedstream takes place to produce a first raw gas stream. The bottom of the first reaction chamber is frusto-conical or hemispherical shaped. The apparatus also comprises a coaxial free-flow refractory lined gas diversion chamber with an upper inlet and side and bottom outlets located below the first reaction chamber.

Jahnke, F.C.

1987-03-03

237

Understanding selective oxidations.  

PubMed

Functionalizing organic molecules is an important value-creating step throughout the entire chemical value-chain. Oxyfunctionalization of e.g. C-H or C=C bonds is one of the most important functionalization technologies used industrially. The major challenge in this field is the prevention of side reactions and/or the consecutive over-oxidation of the desired products. Despite its importance, a fundamental understanding of the intrinsic chemistry, and the subsequent design of a tailored engineering environment, is often missing. Industrial oxidation processes are indeed to a large extent based on empirical know-how. In this mini-review, we summarize some of our previous work to help to bridge this knowledge gap and elaborate on our ongoing research. PMID:21138187

Neuenschwander, Ulrich; Turrą, Natascia; Aellig, Christof; Mania, Philipp; Hermans, Ive

2010-01-01

238

Silver oxide cells  

SciTech Connect

The silver oxide cell is constructed so as to dispose, at the cathode side, of a cathodic material layer composed of AgO and a reducing layer for reducing AgO and, at the anode side, of an anodic material layer and an electrolyte layer in a container composed of a cathode can an anode cap and a gasket. The cathodic material layer is covered at the surface thereof with a reduced layer formed by the reduction of AgO. The silver oxide cell enables a discharge on the single voltage level as in Ag/sub 2/O cells, and is appropriate for large-scale production and favorable in workability.

Nagaura, T.

1983-09-20

239

Selective methane oxidation over promoted oxide catalysts  

SciTech Connect

Principal accomplishments have been achieved in all three areas of selective catalytic oxidation of methane that have been pursued in this research project. These accomplishments are centered on the development of catalyst systems that produce high space time yields of C{sub 2} hydrocarbon products, formaldehyde, and methanol from methane/air mixtures at moderate temperatures and at ambient pressure. The accomplishments can be summarized as the following: the SO{sub 4}{sup 2{minus}}/SrO/La{sub 2}O{sub 3} catalyst developed here has been further optimized to produce 2 kg of C{sub 2} hydrocarbons/kg catalyst/hr at 550C; V{sub 2}O{sub 5}SiO{sub 2} catalysts have been prepared that produce up to 1.5 kg formaldehyde/kg catalyst/hr at 630C with CO{sub 2} selectivities; and a novel dual bed catalyst system has been designed and tested that produces over 100 g methanol/kg catalyst/hr at 600C.

Klier, K.; Herman, R.G.

1995-06-01

240

Biologically inspired oxidation catalysis  

Microsoft Academic Search

The development of processes for selective hydrocarbon oxidation is a goal that has long been pursued. An additional challenge is to make such processes environmentally friendly, for example by using non-toxic reagents and energy-efficient catalytic methods. Excellent examples are naturally occurring iron- or copper-containing metalloenzymes, and extensive studies have revealed the key chemical principles that underlie their efficacy as catalysts

Lawrence Que; William B. Tolman

2008-01-01

241

Toxicology of nitrous oxide  

Microsoft Academic Search

Since the first description of its anaesthetic effects by Horace Wells in 1844, nitrous oxide (N2O) or ‘laughing-gas’ was, for a long period, considered to be an inert gas. However, since Lassen, in 1956, published details of the occurrence of aplastic anaemia and septicaemia in patients after prolonged N2O-exposure, we know that there are toxicological effects.The majority of these secondary

Jessika Takįcs

2001-01-01

242

Controlled CO preferential oxidation  

DOEpatents

Method for controlling the supply of air to a PROX reactor for the preferential oxidation in the presence of hydrogen wherein the concentration of the hydrogen entering and exiting the PROX reactor is monitored, the difference therebetween correlated to the amount of air needed to minimize such difference, and based thereon the air supply to the PROX reactor adjusted to provide such amount and minimize such difference.

Meltser, Mark A. (Pittsford, NY); Hoch, Martin M. (Webster, NY)

1997-01-01

243

Partial oxidation process  

Microsoft Academic Search

A continuous process for preventing the build-up of metals from the hydrocarbonaceous fuel feed in a partial oxidation system in which about 80-100 wt. % of the carbon-soot produced is recycled to the gas generator. By the subject process a significantly large portion of the metals and metal compounds i.e. ash in the soot-water feed stream to the decanter become

R. M. Dille; L. E. Estabrook; H. A. Rhodes; G. N. Richter; J. G. P. Rohner

1984-01-01

244

Plutonium oxide dissolution  

Microsoft Academic Search

Several processing options for dissolving plutonium oxide (PuO[sub 2]) from high-fired materials have been studied. The scoping studies performed on these options were focused on PuO[sub 2] typically generated by burning plutonium metal and PuO[sub 2] produced during incineration of alpha contaminated waste. At least two processing options remain applicable for dissolving high-fired PuO[sub 2] in canyon dissolvers. The options

Gray

1992-01-01

245

Plutonium oxide dissolution  

Microsoft Academic Search

Several processing options for dissolving plutonium oxide (PuOā) from high-fired materials have been studied. The scoping studies performed on these options were focused on PuOā typically generated by burning plutonium metal and PuOā produced during incineration of alpha contaminated waste. At least two processing options remain applicable for dissolving high-fired PuOā in canyon dissolvers. The options involve solid solution formation

Gray

1992-01-01

246

Nitric oxide in invertebrates  

Microsoft Academic Search

Nitric oxide (NO) is considered an important signaling molecule implied in different physiological processes, including nervous\\u000a transmission, vascular regulation, immune defense, and in the pathogenesis of several diseases. The presence of NO is well\\u000a demonstrated in all vertebrates. The recent data on the presence and roles of NO in the main invertebrate groups are reviewed\\u000a here, showing the widespread diffusion

Marco Colasanti; Giorgio Venturini

1998-01-01

247

Monolithic diesel oxidation catalysts  

Microsoft Academic Search

A flow-through ceramic monolithic catalyst, containing bulk CeO2 as the catalytically active component, is reported for the catalytic oxidation of the liquid portion of the particulates present in diesel engine exhausts. This new technology has been successfully implemented into medium duty trucks in the U.S. beginning in 1994 meeting all required emission standards. Catalyst screening and engine durability\\/aging results and

Robert J. Farrauto; Kenneth E. Voss

1996-01-01

248

Oxide heterostructure resistive memory.  

PubMed

Resistive switching devices are widely believed as a promising candidate for future memory and logic applications. Here we show that by using multilayer oxide heterostructures the switching characteristics can be systematically controlled, ranging from unipolar switching to complementary switching and bipolar switching with linear and nonlinear on-states and high endurance. Each layer can be tailed for a specific function during resistance switching, thus greatly improving the degree of control and flexibility for optimized device performance. PMID:23724783

Yang, Yuchao; Choi, ShinHyun; Lu, Wei

2013-06-04

249

Hemoglobin oxidative stress  

NASA Astrophysics Data System (ADS)

Venous blood obtained from healthy donors and from patients suffering from breast cancer have been treated with acetylphenylhydrazine (APH) for different time. Mössbauer spectra of the packed red cells have been recorded and compared. The largest difference occurs after 50 min of treatment with APH where the patient samples show a broad spectral pattern indicating an advanced hemoglobin oxidation. These results may have some relevance in early cancer diagnosis.

Croci, S.; Ortalli, I.; Pedrazzi, G.; Passeri, G.; Piccolo, P.

2000-07-01

250

A comparative evaluation of cobalt chromium oxide, cobalt manganese oxide, cobalt manganese oxide, and copper manganese oxide as catalysts for the water-gas shift reaction  

Microsoft Academic Search

Cobalt chromium oxide, cobalt manganese oxide, and copper manganese oxide have been compared as catalysts for the water-gas shift reaction. Cobalt chromium oxide and cobalt manganese oxide catalysts can give both high activity and long lifetimes for this reaction. Cobalt chromium oxide catalysts display higher activity compared to the other catalyst systems and this is shown that both the cobalt

G. J. Hutchings; R. G. Copperthwaite; F. M. Gottschalk; R. Hunter; J. Mellor; S. W. Orchard; T. Sangiorgio

1992-01-01

251

Oxide Ferromagnetic Semiconductors  

NASA Astrophysics Data System (ADS)

The field of oxide ferromagnetic semiconductors has witnessed tremendous interest and activity over the past few years, especially in the context of realization of intrinsic oxide based diluted magnetic semiconductors (O-DMS). In this talk I will review the important developments in this field, highlighting apparent successes, concerns and questions. Research results obtained by various groups on a number of systems such as transition element (especially Co, Mn, Cr) doped TiO2, ZnO, La1-xSrxTiO3, HfO2 will be discussed including some related device efforts involving spin transport and field induced modulation of magnetization. Some cases of undoped or dual doped oxide films will also be addressed. In the light of the potentially serious possibility of extrinsic effects in most systems the significance of the choice and implementation of an appropriate characterization scheme will also be highlighted. Collaborators : T. Venkatesan, Nigel Browning, Y. V. Idzerda, R. Ramesh, D. K. Kundaliya, S. X. Zhang, L. F. Fu, S. Dhar, A. Lussier, S. R. Shinde, Y. Zhao, M. S. R. Rao, T. Zhao.

Ogale, Satishchandra

2006-03-01

252

Magnetic Oxide Superlattices  

NASA Astrophysics Data System (ADS)

Atomically regulated interfaces and superlattices composed of oxides are very interesting research arena for physics and possible applications. By selecting magnetic oxides as one of the components, one can study basic phenomena of spin polarized electrons at the interfaces [1]. Also, one can realized ?multiferroics? at the interface because magnetization and electric dipole due to interface charge imbalance can coexist. We demonstrated that non-linear Kerr effect [2] can be a tool of detecting interface magnetism in ?tricolor superlattices? composed of asymmetric A-B-C-A-B-C- sequence with A, B, and C being component oxides [3]. This technique was successfully applied to detect, design and enhance interface magnetism in a single heterointerface [4]. We now extend the artificially built-in multiferroic superlattices to other sequences, which include DNA superlattices (D: donor, N: neutral, and A: acceptor) and Ratchet superlattices (asymmetric doping profile). We also demonstrate realization of interface ferromagnetism at pn junctions made of two Mott insulators and tuning the magnitude through the channels of orbital and charge degrees of freedom. [1] M. Izumi et. al., J. Phys. Soc. Jpn., 71, 2621 (2002), Phys. Rev. B 64, 064429 (2001). [2] Y. Ogawa, et. al., Phys. Rev. Lett., 90. 217403 (2003). [3] H. Yamada, at. al., Appl. Phys. Lett., 80, 622 (2002). [4] H. Yamada, et. al., Science, 305, 646 (2004).

Kawasaki, Masashi

2006-03-01

253

Anodic Aluminum Oxide Diodes  

NASA Astrophysics Data System (ADS)

During anodic oxidation of aluminum, the incorporated anion species from the electrolyte are drawn into the growing barrier layer at the pore base by the high electric field and, afterward, migrate inward. The barrier layer consists of acid anion-contaminated regions adjacent to the oxide/electrolyte interface and relatively pure alumina further away from it. It can be presumed that there is a depletion layer region in between the acid anion-contaminated material and the pure alumina material. This study investigates the diode characteristics of the anodic aluminum oxide (AAO) film based on the depletion layer region presumption. Different electrolyte acids are employed to fabricate AAO diodes which possess different electrical properties. The current--voltage (I--V) characteristic curves indicate that the AAO devices possess the electrical property of a diode, especially the sulfuric acid processed AAO. It was observed that the threshold voltages for the sulfuric acid, oxalic acid, and phosphoric acid are 3.3, 8, and 16 V, respectively. This fits in with the sequential order presumption of the p, n depletion layer thicknesses for these three electrolyte acids.

Chang, Cheng-Yao; Wang, Gou-Jen

2011-07-01

254

Magnetoplumbite-related oxides  

SciTech Connect

These ferrites were prepared from Fe{sub 2}O{sub 3}, MO oxides (M = Ba,Sr,Pb) and MeO oxides (Me = Mg,Mn,Co,Zn). Chemical compositions of the main barium ferrites (M = Ba) are represented in a ternary diagram. The structures of these various compounds (M,Y,W,Z,X,U) are closely related. The simplest one is the compound BaFe{sub 12}O{sub 19} (M). Its crystal structure is similar to that of the mineral magnetoplumbite PbFe{sub 7.5}Mn{sub 3.5}Al{sub 0.5}O{sub 19} (PbM{sub 12}O{sub 19}) (5). For this reason the hexagonal ferrites are also known as magnetoplumbite-type ferrites (called MP-type in this paper). When the Fe{sup 3+} ions are replaced by other trivalent ions, such as Al{sup 3+}, Ga{sup 3+}, another group of MP-type oxides, namely AB{sub 12}O{sub 19} (A = Ba{sup 2+} or a large divalent ion; B = Al{sup 3+} or Ga{sup 3+}) is obtained. In this paper, the authors briefly review ideal structure and major properties and uses, especially in the case of ferrites.

Collongues, R.; Gourier, D.; Kahn-Harari, A.; Lejus, A.M.; Thery, J.; Vivien, D. (Lab. de Chimie Appliquee de l'Etat Solide, Ecole National Superieure de Chimie de Paris, 11 rue Pierre et Marie Curie, 75005 Paris (FR))

1990-01-01

255

Alkane oxidation by osmium tetroxide.  

PubMed

Aqueous alkaline OsO4 at 85 degrees C oxidizes saturated alkanes, including primary, secondary, and tertiary C-H bonds. Isobutane affords tert-butanol in quantitative yield based on consumed OsO4. Cyclohexane is oxidized to a mixture of adipate and succinate. Ethane and propane are oxidized to acetate, which itself is further oxidized under the reaction conditions. A few turnovers of isobutane oxidation have been accomplished using NaIO4 as the terminal oxidant. The alkane oxidation is an example of ligand accelerated catalysis, as hydroxide binding to OsO4 is required for reaction. A concerted mechanism involving [3+2] addition of a C-H bond to two oxo groups of OsO4(OH)- is suggested, analogous to the pathways for dihydroxylation of alkenes by OsO4(L) and for addition of H2 to OsO4(L). PMID:15740101

Bales, Brian C; Brown, Peter; Dehestani, Ahmad; Mayer, James M

2005-03-01

256

Wet oxidation catalyzed by ruthenium supported on cerium (IV) oxides  

Microsoft Academic Search

The activity of precious meta catalysts in the wet oxidation of organic compounds was investigated. Ruthenium was the most active catalyst among the precious metals examined, and cerium (IV) oxide was the most effective support. The Ru\\/Ce catalyst rivaled homogeneous copper catalyst, which is used in the practical wastewater treatment, for the oxidation of n-propyl alcohol, n-butyl alcohol, phenol, acetamide,

Seiichiro Imamura; Ikumi Fukuda; Shingo Ishida

1988-01-01

257

Renal oxidant injury and oxidant response induced by mercury  

Microsoft Academic Search

Renal oxidant injury and oxidant response induced by mercury. The role of oxidative stress in mercuric chloride (HgCl2)-induced nephrotoxicity is uncertain and controversial. We demonstrate that LLC-PK1 cells, exposed to HgCl2, generate massive amounts of hydrogen peroxide, the latter completely quenched by the hydrogen peroxide scavenger, pyruvate. HgCl2 exerts a dose-dependent cytotoxicity which is attenuated by pyruvate and catalase. Cellular

Karl A Nath; Anthony J Croatt; Scott Likely; Tim W Behrens; David Warden

1996-01-01

258

Role of oxidative stress and nitric oxide in atherothrombosis  

PubMed Central

During the last decade basic and clinical research has highlighted the central role of reactive oxygen species (ROS) in cardiovascular disease. Enhanced production or attenuated degradation of ROS leads to oxidative stress, a process that affects endothelial and vascular function, and contributes to vascular disease. Nitric oxide (NO), a product of the normal endothelium, is a principal determinant of normal endothelial and vascular function. In states of inflammation, NO production by the vasculature increases considerably and, in conjunction with other ROS, contributes to oxidative stress. This review examines the role of oxidative stress and NO in mechanisms of endothelial and vascular dysfunction with an emphasis on atherothrombosis.

Lubos, Edith; Handy, Diane E.; Loscalzo, Joseph

2008-01-01

259

Unusual inherent electrochemistry of graphene oxides prepared using permanganate oxidants.  

PubMed

Graphene and graphene oxides are materials of significant interest in electrochemical devices such as supercapacitors, batteries, fuel cells, and sensors. Graphene oxides and reduced graphenes are typically prepared by oxidizing graphite in strong mineral acid mixtures with chlorate (Staudenmaier, Hofmann) or permanganate (Hummers, Tour) oxidants. Herein, we reveal that graphene oxides pose inherent electrochemistry, that is, they can be oxidized or reduced at relatively mild potentials (within the range ±1?V) that are lower than typical battery potentials. This inherent electrochemistry of graphene differs dramatically from that of the used oxidants. Graphene oxides prepared using chlorate exhibit chemically irreversible reductions, whereas graphene oxides prepared through permanganate-based methods exhibit very unusual inherent chemically reversible electrochemistry of oxygen-containing groups. Insight into the electrochemical behaviour was obtained through cyclic voltammetry, chronoamperometry, and X-ray photoelectron spectroscopy experiments. Our findings are of extreme importance for the electrochemistry community as they reveal that electrode materials undergo cyclic changes in charge/discharge cycles, which has strong implications for energy-storage and sensing devices. PMID:23934966

Eng, Alex Yong Sheng; Ambrosi, Adriano; Chua, Chun Kiang; San?k, Filip; Sofer, Zden?k; Pumera, Martin

2013-08-09

260

Wet oxidation catalyzed by ruthenium supported on cerium (IV) oxides  

SciTech Connect

The activity of precious meta catalysts in the wet oxidation of organic compounds was investigated. Ruthenium was the most active catalyst among the precious metals examined, and cerium (IV) oxide was the most effective support. The Ru/Ce catalyst rivaled homogeneous copper catalyst, which is used in the practical wastewater treatment, for the oxidation of n-propyl alcohol, n-butyl alcohol, phenol, acetamide, poly (propylene glycol), and acetic acid. In addition, it was especially effective for the oxidation of some compounds with high oxygen content such as poly (ethylene glycol), ethylene glycol, formaldehyde, and formic acid.

Imamura, S.; Fukuda, I.; Ishida, S.

1988-04-01

261

Oxidative Metabolism in Muscle  

NASA Astrophysics Data System (ADS)

Oxidative metabolism is the dominant source of energy for skeletal muscle. Near-infrared spectroscopy allows the non-invasive measurement of local oxygenation, blood flow and oxygen consumption. Although several muscle studies have been made using various near-infrared optical techniques, it is still difficult to interpret the local muscle metabolism properly. The main findings of near-infrared spectroscopy muscle studies in human physiology and clinical medicine are summarized. The advantages and problems of near-infrared spectroscopy measurements, in resting and exercising skeletal muscles studies, are discussed through some representative examples.

Ferrari, M.; Binzoni, T.; Quaresima, V.

1997-06-01

262

Oxidative stress in cyanobacteria.  

PubMed

Reactive oxygen species (ROS) are byproducts of aerobic metabolism and potent agents that cause oxidative damage. In oxygenic photosynthetic organisms such as cyanobacteria, ROS are inevitably generated by photosynthetic electron transport, especially when the intensity of light-driven electron transport outpaces the rate of electron consumption during CO(2) fixation. Because cyanobacteria in their natural habitat are often exposed to changing external conditions, such as drastic fluctuations of light intensities, their ability to perceive ROS and to rapidly initiate antioxidant defences is crucial for their survival. This review summarizes recent findings and outlines important perspectives in this field. PMID:18834454

Latifi, Amel; Ruiz, Marion; Zhang, Cheng-Cai

2008-09-23

263

Oxidizing Borcherds symmetries  

NASA Astrophysics Data System (ADS)

The tensor hierarchy of maximal supergravity in D dimensions is known to be closely related to a Borcherds (super)algebra that is constructed from the global symmetry group E 11- D . We here explain how the Borcherds algebras in different dimensions are embedded into each other and can be constructed from a unifying Borcherds algebra. The construction also has a natural physical explanation in terms of oxidation. We then go on to show that the Hodge duality that is present in the tensor hierarchy has an algebraic counterpart. For D > 8 the Borcherds algebras we find differ from the ones existing in the literature although they generate the same tensor hierarchy.

Kleinschmidt, Axel; Palmkvist, Jakob

2013-03-01

264

Ultra supercritical steamside oxidation  

SciTech Connect

Ultra supercritical (USC) power plants offer the promise of higher efficiencies and lower emissions, which are part of the U.S. Department of Energy's Vision 21 goals. Most current coal power plants in the U.S. operate at a maximum steam temperature of 538 C. However, new supercritical plants worldwide are being brought into service with steam temperatures of up to 620 C. Vision 21 goals include steam temperatures of up to 760 C. This research examines the steamside oxidation of advanced alloys for use in USC systems. Emphasis is placed on alloys for high- and intermediate-pressure turbine sections. Initial results of this research are presented.

Holcomb, Gordon R.; Covino, Bernard S., Jr.; Bullard, Sophie J.; Cramer, Stephen D.; Ziomek-Moroz, M.; Alman, David A.; Ochs, Thomas L.

2004-01-01

265

Nitrogen Oxide Calculator  

NSDL National Science Digital Library

In this activity, students will analyze their nitrogen oxide emissions from all sources (including coal-fired power plants, natural gas combustion, gas-powered lawnmowers, etc.) and combine them with vehicle emissions calculated in the previous activity (Ground-level Ozone: Your Vehicle) to derive an estimate of total emissions of smog-forming NOx. They will use an online nitrogen calculator and enter values for private transportation, public transportation, heat and power, and number of people living the household to receive the total emissions figure.

Pratte, John

2008-12-17

266

PLATES WITH OXIDE INSERTS  

DOEpatents

Planar-type fuel assemblies for nuclear reactors are described, particularly those comprising fuel in the oxide form such as thoria and urania. The fuel assembly consists of a plurality of parallel spaced fuel plate mennbers having their longitudinal side edges attached to two parallel supporting side plates, thereby providing coolant flow channels between the opposite faces of adjacent fuel plates. The fuel plates are comprised of a plurality of longitudinally extending tubular sections connected by web portions, the tubular sections being filled with a plurality of pellets of the fuel material and the pellets being thermally bonded to the inside of the tubular section by lead.

West, J.M.; Schumar, J.F.

1958-06-10

267

PREPARATION OF REFRACTORY OXIDE MICROSPHERE  

DOEpatents

A method is described of preparing thorium oxide in the form of fused spherical particles about 1 to 2 microns in diameter. A combustible organic solution of thorium nitrate containing additive metal values is dispersed into a reflected, oxygen-fed flame at a temperature above the melting point of the resulting oxide. The metal additive is aluminum at a proportion such as to provide 1 to 10 weight per cent aluminum oxide in the product, silicon at the same proportion, or beryllium at a proportion of 12 to 25 weight per cent beryllium oxide in the product. A minor proportion of uranium values may also be provided in the solution. The metal additive lowers the oxide melting point and allows fusion and sphere formation in conventional equipment. The product particles are suitable for use in thorium oxide slurries for nuclear reactors. (AEC)

Haws, C.C. Jr.

1963-09-24

268

A germanate transparent conductive oxide  

PubMed Central

Wide bandgap conductors such as In2O3 and ZnO are used as transparent conducting oxides (TCOs). To date, TCOs are realized using post transition metal cations with largely spread s-orbitals such as In3+, Sn4+, Zn2+ and Cd2+. On the other hand, no good electronic conductor has been realized in oxides of Al, Si and Ge. Here we report the conversion of an oxide of Ge into a good electronic conductor by employing the concept of superdegeneracy. We find that cubic SrGeO3, synthesized under high pressure, displays a direct bandgap of 3.5?eV, a carrier mobility of 12?cm2(Vs)?1, and conductivities of 3?Scm?1 (DC) and 400?Scm?1 (optical conductivity). This is the first Ge-based electronic conductive oxide, and expands the family of TCOs from ionic oxides to covalent oxides.

Mizoguchi, Hiroshi; Kamiya, Toshio; Matsuishi, Satoru; Hosono, Hideo

2011-01-01

269

Zinc oxide varistors and/or resistors  

DOEpatents

Varistors and/or resistors that includes doped zinc oxide gel microspheres. The doped zinc oxide gel microspheres preferably have from about 60 to about 95% by weight zinc oxide and from about 5 to about 40% by weight dopants based on the weight of the zinc oxide. The dopants are a plurality of dopants selected from silver salts, boron oxide, silicon oxide and hydrons oxides of aluminum, bismuth, cobalt, chromium, manganese, nickel, and antimony.

Arnold, Jr., Wesley D. (Oak Ridge, TN); Bond, Walter D. (Knoxville, TN); Lauf, Robert J. (Oak Ridge, TN)

1993-01-01

270

Angiotensin II and Oxidative Stress  

Microsoft Academic Search

\\u000a There is an increasing body of evidence that oxidative stress markedly contributes to endothelial dysfunction and to poor\\u000a prognosis in patients with coronary artery disease and hypertension. Among many stimuli for oxidative stress in vascular tissue,\\u000a the role of angiotensin II has been extensively studied. When given acutely, angiotensin II stimulates the release of nitric\\u000a oxide and activates a nonphagocytic

N. Tsilimingas; A. Warnholtz; M. Wendt; T. Münzel

271

Electrochemical oxidation of chemical weapons  

Microsoft Academic Search

Catalyzed electrochemical oxidation (CEO), a low-temperature electrochemical oxidation technique, is being examined for its potential use in destroying chemical warfare agents. The CEO process oxidizes organic compounds to form carbon dioxide and water. A bench-scale CEO system was used in three separate tests sponsored by the US Department of Energy`s (DOE) Office of Intelligence and National Security through the Advanced

Surma

1994-01-01

272

Enzymes of respiratory iron oxidation  

SciTech Connect

This report focuses on the progress made in three areas of research concerned with enzymes involved in respiratory iron oxidation. The three areas are as follows: development of an improved procedure for the routine large scale culture of iron oxidizing chemolithotrophs based on the in-situ electrolysis of the soluble iron in the growth medium; to perform iron oxidation kinetic studies on whole cells using the oxygen electrode; and to identify, separate, purify, and characterize the individual cellular components.

Blake, R. II.

1991-01-01

273

MOLTEN SALT OXIDATION OF CHLOROBENZENE  

Microsoft Academic Search

This investigation focuses on the oxidation of chlorobenzene izn a laboratory-scale molten salt reactor. A Fourier transform infrared spectrometer with a long-path cell is used to monitor the organic waste oxidation process, including the formation of by-products as a function of temperature. The measured oxidation by-products are compared with results reported in the literature and are obtained in a combustion-driven

S. PANDETI; S. G. BUCKLEY

2004-01-01

274

Oxidative desulfurization of residual oils  

Microsoft Academic Search

Sulfur removal from a 288Ā°C Reduced Arabian Crude can be accomplished by selective oxidation of the thiophenes to sulfones, followed by a high temperature potassium hydroxide treatment. Effective sulfur oxidation is achieved by tertiary butyl hydroperoxide in the presence of oil-soluble catalysts containing molybdenum, vanadium, or titanium. Under best conditions, sulfur removal by the oxidative process ranges from 50 to

S. Herbstman; J. Patel

1982-01-01

275

Oxidative behavior of hydrocarbon lubricants  

Microsoft Academic Search

A micro-oxidation tester in conjunction with gel permeation chromatography and clay percolation has been used to study the high temperature oxidation of mineral oil lubricants. (A thin film of a mineral oil lubricant on a metal surface thus simulating the piston-ring cylinder conditions of an internal combustion engine). Oxidation studies reveal higher reaction rates for super-refined than for conventionally refined

1982-01-01

276

Catalytic reduction of nitrogen oxides  

Microsoft Academic Search

This patent describes a method for catalytically reducing one or more nitrogen oxides from a gaseous stream containing one or more nitrogen oxides and one or more sulfur oxides. It comprises contacting the gaseous stream and ammonia with a microporous non-zeolitic molecular sieve composition at effective reduction conditions, wherein the microporous non-zeolitic molecular sieve composition is hydrogen-forming cation exchanged prior

M. T. Staniulis; A. P. Risch

1989-01-01

277

TREK-1 is a heat-activated background K+ channel  

PubMed Central

Peripheral and central thermoreceptors are involved in sensing ambient and body temperature, respectively. Specialized cold and warm receptors are present in dorsal root ganglion sensory fibres as well as in the anterior/preoptic hypothalamus. The two-pore domain mechano-gated K+ channel TREK-1 is highly expressed within these areas. Moreover, TREK-1 is opened gradually and reversibly by heat. A 10°C rise enhances TREK-1 current amplitude by ?7-fold. Prostaglandin E2 and cAMP, which are strong sensitizers of peripheral and central thermoreceptors, reverse the thermal opening of TREK-1 via protein kinase A-mediated phosphorylation of Ser333. Expression of TREK-1 in peripheral sensory neurons as well as in central hypothalamic neurons makes this K+ channel an ideal candidate as a physiological thermoreceptor.

Maingret, Francois; Lauritzen, Inger; Patel, Amanda J.; Heurteaux, Catherine; Reyes, Roberto; Lesage, Florian; Lazdunski, Michel; Honore, Eric

2000-01-01

278

Optimized deployment of heat-activated surgical staples using thermography  

NASA Astrophysics Data System (ADS)

We have developed a suture analogue, suitable for use in laparoscopic surgery, in the form of a staple constructed from NiTi shape memory alloy (SMA). Closure of the staple is effected by resistive heating via a (50-100 ms) pulse of electrical current (~5 A). In order to optimize deployment protocols and minimize thermal collateral damage to tissue, the heat sink effect of the electrical contact rails, as well as the presence of contact hotspots must be considered. Here, we have employed high-resolution thermal imaging to observe the dynamic temperature distributions in SMA staples as a function of the pulse parameters. This has facilitated process optimization and also provided data from which to validate computational finite-element models of the heat transport phenomena.

Ng, Y.; Song, C.; McLean, D.; Shimi, S. M.; Frank, T. G.; Cuschieri, A.; Campbell, P. A.

2003-09-01

279

Interface-confined oxide nanostructures for catalytic oxidation reactions.  

PubMed

Heterogeneous catalysts, often consisting of metal nanoparticles supported on high-surface-area oxide solids, are common in industrial chemical reactions. Researchers have increasingly recognized the importance of oxides in heterogeneous catalysts: that they are not just a support to help the dispersion of supported metal nanoparticles, but rather interact with supported metal nanoparticles and affect the catalysis. The critical role of oxides in catalytic reactions can become very prominent when oxides cover metal surfaces forming the inverse catalysts. The source of the catalytic activity in homogeneous catalysts and metalloenzymes is often coordinatively unsaturated (CUS) transition metal (TM) cations, which can undergo facile electron transfer and promote catalytic reactions. Organic ligands and proteins confine these CUS cations, making them highly active and stable. In heterogeneous catalysis, however, confining these highly active CUS centers on an inorganic solid so that they are robust enough to endure the reaction environment while staying flexible enough to perform their catalysis remains a challenge. In this Account, we describe a strategy to confine the active CUS centers on the solid surface at the interface between a TM oxide (TMO) and a noble metal (NM). Among metals, NMs have high electron negativity and low oxygen affinity. This means that TM cations of the oxide bind strongly to NM atoms at the interface, forming oxygen-terminated-bilayer TMO nanostructures. The resulting CUS sites at the edges of the TMO nanostructure are highly active for catalytic oxidation reactions. Meanwhile, the strong interactions between TMOs and NMs prevent further oxidation of the bilayer TMO phases, which would otherwise result in the saturation of oxygen coordination and the deactivation of the CUS cations. We report that we can also tune the oxide-metal interactions to modulate the bonding of reactants with CUS centers, optimizing their catalytic performance. We review our recent progress on oxide-on-metal inverse catalysts, mainly the TMO-on-Pt (TM = Fe, Co, and Ni) systems and discuss the interface-confinement effect, an important factor in the behavior of these catalytic systems. We have studied both model catalyst systems and real supported nanocatalysts. Surface science studies and density functional theory calculations in model systems illustrate the importance of the oxide-metal interfaces in the creation and stabilization of surface active centers, and reveal the reaction mechanism at these active sites. In real catalysts, we describe facile preparation processes for fabricating the oxide-on-metal nanostructures. We have demonstrated excellent performance of the inverse catalysts in oxidation reactions such as CO oxidation. We believe that the interface confinement effect can be employed to design highly efficient novel catalysts and that the inverse oxide-on-metal catalysts may find wide applications in heterogeneous catalysis. PMID:23458033

Fu, Qiang; Yang, Fan; Bao, Xinhe

2013-03-04

280

Oxidation resistant coatings for molybdenum  

SciTech Connect

As an article of manufacture, a molybdenum element is described comprising a molybdenum substrate in which the substrate has adherently bonded thereto a thermally self-healing plasma-sprayed coating consisting essentially of a composite of molybdenum and a refractory oxide material capable of reacting with molybdenum oxide under oxidizing conditions to form a substantially thermally stable refractory compound of molybdenum. The plasma-sprayed coating is formed of interbonded plasma-sprayed layers of a composite of molybdenum/refractory oxide material produced from a particulate mixture thereof. The bonded layers range from a first layer adjacent to the substrate to an Nth or last layer.

Timmons, G.A.

1988-05-17

281

Oxidic materials: an endless frontier.  

PubMed

Selected areas of heterogeneous catalysis involving nanoporous oxides in the context of clean technology, green chemistry and sustainability are highlighted in this overview. So also is the potential of oxidic membranes in the context of producing hydrogen from water at high temperatures; and a brief survey is given of strategies that are required for the design of better oxidic photocatalysts for the conversion of visible light to H2 and O2. Aspects of physico-chemical characterization of advanced oxidic materials are also outlined. PMID:23812499

Thomas, John Meurig

2013-08-28

282

Buried oxide layer in silicon  

DOEpatents

A process for forming Silicon-On-Insulator is described incorporating the steps of ion implantation of oxygen into a silicon substrate at elevated temperature, ion implanting oxygen at a temperature below 200.degree. C. at a lower dose to form an amorphous silicon layer, and annealing steps to form a mixture of defective single crystal silicon and polycrystalline silicon or polycrystalline silicon alone and then silicon oxide from the amorphous silicon layer to form a continuous silicon oxide layer below the surface of the silicon substrate to provide an isolated superficial layer of silicon. The invention overcomes the problem of buried isolated islands of silicon oxide forming a discontinuous buried oxide layer.

Sadana, Devendra Kumar (Pleasantville, NY); Holland, Orin Wayne (Lenoir, TN)

2001-01-01

283

Materials Modification in Nanotechnology: Oxidation  

NSDL National Science Digital Library

This PowerPoint created and presented by the Nanotechnology Applications and Career Knowledge (NACK) Center introduces students to oxidation. It goes over the various types of oxide Ć¢ĀĀ native, gate, field, etc. It discusses dry vs. wet oxidation, high pressure oxidation, chemical vapor deposition and has a section on modifying dielectric constant. This is a great resource for any classroom looking at nanofabrication modifications. This and all other valuable resources from the NACK Center require a fast, easy, free log-in.

2010-03-22

284

Oxidation = group theory  

NASA Astrophysics Data System (ADS)

Dimensional reduction of theories involving (super)gravity gives rise to sigma models on coset spaces of the form G/H, with G being a non-compact group, and H its maximal compact subgroup. The reverse process, called oxidation, is the reconstruction of the possible higher-dimensional theories, given the lower-dimensional theory. In three dimensions, all degrees of freedom can be dualized to scalars. Given the group G for a three-dimensional sigma model on the coset G/H, we demonstrate an efficient method for recovering the higher-dimensional theories, essentially by decomposition into subgroups. The equations of motion, Bianchi identities, Kaluza-Klein modifications and Chern-Simons terms are easily extracted from the root lattice of the group G. We briefly discuss some aspects of oxidation from the E8(8)/SO(16) coset, and demonstrate that our formalism reproduces the Chern-Simons term of 11D supergravity, knows about the T-duality of IIA and IIB theory, and easily deals with self-dual tensors, like the 5-tensor of IIB supergravity.

Keurentjes, Arjan

2003-06-01

285

Nitric oxide and cancer  

PubMed Central

Nitric oxide (NO) is a lipophilic, highly diffusible and short-lived physiological messenger which regulates a variety of important physiological responses including vasodilation, respiration, cell migration, immune response and apoptosis. NO is synthesized by three differentially gene-encoded NO synthase (NOS) in mammals: neuronal NOS (nNOS or NOS-1), inducible NOS (iNOS or NOS-2) and endothelial NOS (eNOS or NOS-3). All isoforms of NOS catalyze the reaction of L-arginine, NADPH and oxygen to NO, L-citrulline and NADP. NO may exert its cellular action by cGMP-dependent as well as by cGMP-independent pathways including postranslational modifications in cysteine (S-nitrosylation or S-nitrosation) and tyrosine (nitration) residues, mixed disulfide formation (S-nitrosoglutathione or GSNO) or promoting further oxidation protein stages which have been related to altered protein function and gene transcription, genotoxic lesions, alteration of cell-cycle check points, apoptosis and DNA repair. NO sensitizes tumor cells to chemotherapeutic compounds. The expression of NOS-2 and NOS-3 has been found to be increased in a variety of human cancers. The multiple actions of NO in the tumor environment is related to heterogeneous cell responses with particular attention in the regulation of the stress response mediated by the hypoxia inducible factor-1 and p53 generally leading to growth arrest, apoptosis or adaptation.

Muntane, Jordi; la Mata, Manuel De

2010-01-01

286

Oxidants, oxidative stress and the biology of ageing  

Microsoft Academic Search

Living in an oxygenated environment has required the evolution of effective cellular strategies to detect and detoxify metabolites of molecular oxygen known as reactive oxygen species. Here we review evidence that the appropriate and inappropriate production of oxidants, together with the ability of organisms to respond to oxidative stress, is intricately connected to ageing and life span.

Toren Finkel; Nikki J. Holbrook

2000-01-01

287

Selective oxidation of isobutane and isobutene over vanadium phosphorus oxides  

Microsoft Academic Search

Vanadium phosphorus oxide (VPO) was prepared by using dodecyl amine as surfactant and tested for the oxidation of isobutane and isobutene. Characterization results (BET, XRD, EPR, and XPS) showed that the structure and property of the VPO catalyst prepared by using dodecyl amine as surfactant is considerably different in comparison with the VPO catalyst synthesized without dodecyl amine. Catalytic tests

Jingqi Guan; Haiyan Xu; Shubo Jing; Shujie Wu; Yuanyuan Ma; Yanqiu Shao; Qiubin Kan

2008-01-01

288

Catalytic water oxidation: Rugged water-oxidation anodes  

Microsoft Academic Search

The efficient catalytic oxidation of water to dioxygen in the solid state is one of the challenges to be overcome to build sun-driven and\\/or electrocatalytic water-splitting devices. Now, an effective water-oxidation hybrid catalyst system has been made by attaching a ruthenium-polyoxometallate complex to a carbon nanotube.

Antoni Llobet

2010-01-01

289

The Oxidative Aging of Model Oxidized Organic Aerosol Systems  

NASA Astrophysics Data System (ADS)

Modeling and predictions of the behavior of highly oxidized organic aerosol components in the atmosphere often fall short in describing such systems, in part because of the difficulty of accessing appropriately high levels of oxidation (equivalent to one or two weeks in the atmosphere) in a laboratory setting. In this work, we present results from the heterogeneous oxidation by hydroxyl radicals (OH) of particles composed of pure citric, tartaric, or 1,2,3,4-butanetetracarboxylic acid, as well as a fulvic acid sample, in a flow tube reactor. The combination of highly oxidized reagent compounds and high concentrations of OH within the reactor allow us to access very high degrees of oxidation relative to previous studies. As OH exposure increases, an increase in carbon oxidation state and a decrease in overall carbon content are observed, consistent with reaction types in which carbon-carbon bonds are broken and molecules become volatilized. At very high exposure levels, however, changes in both oxidation state and carbon content begin to slow. This evolving recalcitrance of OA constituents suggests a framework to determine under what circumstances oxidative aging will strongly affect atmospheric particle evolution.

Kessler, S. H.; Daumit, K. E.; Nah, T.; Smith, J. D.; Worsnop, D. R.; Wilson, K. R.; Kroll, J. H.

2011-12-01

290

Catalysis by Thin Oxide Films and Oxide Nanoparticles  

NASA Astrophysics Data System (ADS)

Model systems for transition and noble metal oxide catalysts, either as thin films or nanoparticles, were prepared by vacuum-deposition of oxides or oxidation of metals (particles, thin films, single crystals). These systems, including Ga2O3, In2O3, V2O3, V2O5, Nb2O5, Pd5O4 and PdO, are well suited for atomic scale characterization by surface-specific methods and for catalytic tests. Investigations of structure and composition were carried out by HRTEM, AFM, STM, SAED, LEED, EDX, XPS and DFT. In many cases, the surface structure of oxides does not coincide with truncations of the known bulk structures. The adsorption properties of the oxide models, in particular those of defects such as oxygen vacancies or step edges, were examined by vibrational spectroscopy (FTIR and SFG) and thermal desorption spectroscopy (TPD) of probe molecules (CO, H2, propane and propene). Together with XPS, quantification of surface coverage was performed. The catalytic activity and selectivity of the model oxides at (near) ambient gas pressure were investigated by microreactor studies of methanol steam reforming (MSR), (inverse) water gas shift (WGS) and CO oxidation. The structural/compositional flexibility of oxides leads to significant challenges in their characterization but also imparts them with exceptional catalytic properties.

Rupprechter, Günther; Penner, Simon

291

HYDROCARBON OXIDATION OVER VANADIUM PHOSPHORUS OXIDE CATALYST USING HYDROGEN PEROXIDE  

EPA Science Inventory

Selective oxidation of hydrocarbons is one of the very important and challenging areas in industrial chemistry due to the wide ranging utility of the resulting oxygenates in fine chemical synthesis. Most of the existing processes for their oxidations employ toxic and often stoich...

292

Chlorine(Iii) Oxide, a New Chlorine Oxide.  

National Technical Information Service (NTIS)

A chlorine oxide with the empirical formula ClO1.5 was isolated during a study of the decomposition of ClO2. This species is believed to be the new compound chlorine(III) oxide, Cl2O3. Its synthesis and properties are described.

E. T. McHale G. von Elbe

1966-01-01

293

Oxidation mechanisms for alloys in single-oxidant gases  

Microsoft Academic Search

Scales formed on alloys invariably contain the alloy constituents in a ratio different from that in the alloy, owing to the differing thermodynamic tendencies of the alloy components to react with the oxidant and to differences in diffusion rates in scale and alloy phases. This complex interrelationship between transport rates and the thermodynamics of the alloy-oxidant system can be analyzed

Whittle

1981-01-01

294

Oxidative desulfurization of benzene fraction on transition metal oxides  

NASA Astrophysics Data System (ADS)

It is established that molecular oxygen is able to oxidize thiophene selectively in a mixture with benzene on V2O5 · MoO3. The introduction of thiophene inhibits the oxidation of benzene. It is shown that the conversion of thiophene during operation of the catalyst is reduced at first and then increases until it reaches its initial value.

Boikov, E. B.; Vishnetskaya, M. V.

2013-02-01

295

Method for hot pressing beryllium oxide articles  

DOEpatents

The hot pressing of beryllium oxide powder into high density compacts with little or no density gradients is achieved by employing a homogeneous blend of beryllium oxide powder with a lithium oxide sintering agent. The lithium oxide sintering agent is uniformly dispersed throughout the beryllium oxide powder by mixing lithium hydroxide in an aqueous solution with beryllium oxide powder. The lithium hydroxide is converted in situ to lithium carbonate by contacting or flooding the beryllium oxide - lithium hydroxide blend with a stream of carbon dioxide. The lithium carbonate is converted to lithium oxide while remaining fixed to the beryllium oxide particles during the hot pressing step to assure uniform density throughout the compact.

Ballard, A.H.; Godfrey, T.G. Jr.; Mowery, E.H.

1986-10-10

296

Chlorobenzene oxidation using ozone over iron oxide and manganese oxide catalysts  

Microsoft Academic Search

A low-temperature catalytic oxidation of chlorobenzene (CB) has been performed at temperatures of 60–210°C using ozone (O3) over iron oxide and manganese oxide, respectively. In the absence of ozone, CB conversion achieved with these two catalysts at 200°C was below 10%. However, addition of 1200ppm ozone results in a remarkable increase in CB conversion and the conversion reaches 91.7% at

Hou Chuan Wang; Hsu Shang Liang; Moo Been Chang

2011-01-01

297

Room Temperature Chemical Oxidation of Delafossite-Type Oxides  

NASA Astrophysics Data System (ADS)

Examination of the delafossite-type structure of CuLaO2 and CuYO2 suggests that there is room enough to accomodate intercalated oxide ions and the charge compensation resulting simply from the oxidation of an equivalent amount of Cu+ into Cu2+. Reaction with hypohalites in an aqueous solution leads to color change. Evidence of the formation of Cu2+ is given by TGA, iodometric titration, and magnetic (static and EPR) measurements. The obtained La and Y compounds seem to behave in a different way: whereas CuLaO2+x appears as a single phase, CuYO2+x corresponds to a two-phase mixture, with respectively low and high x values, the latter being isostructural with the thermally oxidized compound recently reported by Cava et al. Comparison is stressed between the oxides obtained by oxidation at room and those obtained at higher temperatures.

Trari, M.; Töpfer, J.; Doumerc, J. P.; Pouchard, M.; Ammar, A.; Hagenmuller, P.

1994-07-01

298

Ceramic oxide powders and the formation thereof  

DOEpatents

Ceramic oxide powders and a method for their preparation. Ceramic oxide powders are obtained using a flame process whereby two or more precursors of ceramic oxides are introduced into a counterflow diffusion flame burner wherein said precursors are converted into ceramic oxide powders. The morphology, particle size, and crystalline form of the ceramic oxide powders are determined by process conditions.

Katz, Joseph L. (Baltimore, MD); Hung, Cheng-Hung (Baltimore, MD)

1993-01-01

299

Iridium-tin mixed oxide anode coatings  

Microsoft Academic Search

Mixed oxide coatings of tin and iridium oxide on titanium substrates have been studied over the composition range of 5 to 100 mol % iridium oxide. While stannic oxide behaves as a simple diluent for the electrocatalytically active precious metal oxide, substantial replacement of iridium by tin may be made with little degradation of coating performance in oxygen evolution.

E. N. Balko; P. H. Nguyen

1991-01-01

300

Iron Oxide Based High Temperature Desulfurization Sorbent  

Microsoft Academic Search

Iron oxide sorbent is used as high temperature desulfurization sorbent due to high sulfur capacity, easy regeneration and recovery elemental sulfur. In this paper, the iron oxide based high-temperature sorbent was obtained by mixing iron oxide with calcium oxide, extrudating and calcinating. The sulfidation, reduction and regeneration performance for the prepared iron oxide based desulfurization sorbent were conducted. The phases

Ju Shangguan; Pengfei Hou; Yongjun Zhu; Litong Liang; Fang Shen; Huiling Fan; Maoqian Miao

2009-01-01

301

The oxidation behavior of Co-15 wt % Cr alloy containing dispersed oxides formed by internal oxidation  

SciTech Connect

Internal oxidation pretreatments of Co-15wt%Cr and Co-15wt%Cr-1wt%Ti were carried out using a Rhines pack in quartz, in mullite and in alumina. A dispersion of titanium oxide particles formed in the Ti-containing alloy as a result of the internal oxidation. However, silicon also diffused into all treated specimens when the pretreatments were carried out in quartz or in mullite. The effect of various pretreatments on the subsequent oxidation of these alloys was studied at 1000{degree}C, and compared with that of Co-15wt%Cr-1wt%Si alloy. The main purpose of this study was to determine the relative effectiveness of the dispersed oxide particles and the contaminated silicon on the selective oxidation of chromium. It was found that the oxidation behavior of both treated alloys were strongly affected by the degree of silicon contamination. Selective oxidation of chromium to form a nearly continuous protective Cr{sub 2}O{sub 3} scale was achieved with greater than 0.4wt% silicon. The presence of dispersed particles reduced initial oxidation rate, but was ineffective in promoting Cr{sub 2}O{sub 3} scale formation.

Hou, P.Y.; Shui, Z.R. [Lawrence Berkeley Lab., CA (United States); Stringer, J. [Electric Power Research Inst., Palo Alto, CA (United States)

1991-12-01

302

Ferromagnet / superconductor oxide superlattices  

NASA Astrophysics Data System (ADS)

The growth of heterostructures combining oxide materials is a new strategy to design novel artificial multifunctional materials with interesting behaviors ruled by the interface. With the (re)discovery of colossal magnetoresistance (CMR) materials, there has been renewed interest in heterostructures involving oxide superconductors and CMR ferromagnets where ferromagnetism (F) and superconductivity (S) compete within nanometric distances from the interface. In F/S/F structures involving oxides, interfaces are especially complex and various factors like interface disorder and roughness, epitaxial strain, polarity mismatch etc., are responsible for depressed magnetic and superconducting properties at the interface over nanometer length scales. In this talk I will focus in F/S/F structures made of YBa2Cu3O7 (YBCO) and La0.7Ca0.3MnO3 (LCMO). The high degree of spin polarization of the LCMO conduction band, together with the d-wave superconductivity of the YBCO make this F/S system an adequate candidate for the search of novel spin dependent effects in transport. We show that superconductivity at the interface is depressed by various factors like charge transfer, spin injection or ferromagnetic superconducting proximity effect. I will present experiments to examine the characteristic distances of the various mechanisms of superconductivity depression. In particular, I will discuss that the critical temperature of the superconductor depends on the relative orientation of the magnetization of the F layers, giving rise to a new giant magnetoresistance effect which might be of interest for spintronic applications. Work done in collaboration with V. Peńa^1, Z. Sefrioui^1, J. Garcia-Barriocanal^1, C. Visani^1, D. Arias^1, C. Leon^1 , N. Nemes^2, M. Garcia Hernandez^2, S. G. E. te Velthuis^3, A. Hoffmann^3, M. Varela^4, S. J. Pennycook^4. Work supported by MCYT MAT 2005-06024, CAM GR- MAT-0771/2004, UCM PR3/04-12399 Work at Argonne supported by the Department of Energy, Basic Energy Sciences, contract No.W-31-109-ENG-38. ^1GFMC, Departamento de F'isica Aplicada III, Universidad Complutense de Madrid, 28040 Madrid, Spain ^2Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC). 28049 Cantoblanco. Madrid. ^3Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA ^4Condensed Matter Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6031, USA

Santamaria, Jacobo

2006-03-01

303

The transient oxidation of alloys  

Microsoft Academic Search

The pre-steady-state oxidation of a wide range of binary alloys of practical importance, in 1 atm oxygen at 600° C, is discussed in terms of the main determining parameters, namely the free energies of formation and growth rates of the component and complex oxides, the bulk alloy composition, the alloy interdiffusion coefficient, the oxygen solubility and diffusivity in the alloy,

B. Chattopadhyay; G. C. Wood

1970-01-01

304

ENGINEERING BULLETIN: CHEMICAL OXIDATION TREATMENT  

EPA Science Inventory

Oxidation destroys hazardous contaminants by chemically converting them to nonhazardous or less toxic compounds that are ideally more stable, less mobile, and/or inert. However, under some conditions, other hazardous compounds may be formed. The oxidizing agents most commonly use...

305

Oxidation of Organotrifluoroborates via Oxone®  

PubMed Central

A method for the oxidation of organotrifluoroborates using Oxone® was developed. A variety of aryl-, heteroaryl-, alkenyl-, and alkyltrifluoroborates were converted into the corresponding oxidized products in excellent yields. This method proved to be tolerant of a broad range of functional groups, and in secondary alkyl substrates it was demonstrated to be completely stereospecific.

Molander, Gary A.; Cavalcanti, Livia N.

2011-01-01

306

Nitric oxide in the lung  

Microsoft Academic Search

Nitric oxide is produced by many cell types in the lung and plays an important physiologic role in the regulation of pulmonary vasomotor tone by several known mechanisms. Nitric oxide stimulates soluble guanylyl cyclase, resulting in increased levels of cyclic GMP in lung smooth muscle cells. The gating of K+ and Ca2+ channels by cyclic GMP binding is thought to

Barry Weinberger; Diane E. Heck; Debra L. Laskin; Jeffrey D. Laskin

1999-01-01

307

CATALYTIC DECOMPOSITION OF NITROUS OXIDE  

Microsoft Academic Search

In processing waste gas streams from nuclear fuel plants for recovery of ; the noble gases, nitrous oxide must first be removed. A catalyst consisting of ; 0.5% rhodium supported on 1\\/8-in. alumina pellets has been found capable of ; decomposing nitrous oxide in simulated waste gas streams at catalyst temperatures ; ranging from 343 to 413 C, when gas

Steinberg

1959-01-01

308

Oxidative stress and gene regulation  

Microsoft Academic Search

Reactive oxygen species are produced by all aerobic cells and are widely believed to play a pivotal role in aging as well as a number of degenerative diseases. The consequences of the generation of oxidants in cells does not appear to be limited to promotion of deleterious effects. Alterations in oxidative metabolism have long been known to occur during differentiation

R. G Allen; Maria Tresini

2000-01-01

309

Process of making oxidation products  

Microsoft Academic Search

This patent describes a process of making oxidation products from oxidizable matter by combustion in an internal-combustion engine. The process consists of admitting said oxidizable matter and an amount of an oxidizing agent insufficient for its complete combustion, into the combustion chambers of said engine, and igniting the mixture. This causes combustion to occur therein with the formation of incompletely

Odell

1933-01-01

310

Oxidation Damage in Parkinson's Disease.  

National Technical Information Service (NTIS)

The overall goal of the proposal was to provide a detailed assessment of the role of oxidative damage in Parkinson's Disease (PD) postmortem brain tissue, body fluids of PD patients and in the MPTP model. There were trends towards increased oxidative dama...

M. F. Beal

2003-01-01

311

Opportunities for functional oxides in yttrium oxide-titanium oxide-zirconium oxide system: Applications for novel thermal barrier coatings  

Microsoft Academic Search

This dissertation is an investigation of materials and processed under consideration for next generation thermal structural oxides with potential applications as thermal barrier coatings; wherein, high temperature stability and mechanical properties affect durability. Two notable next generation materials systems under investigation are pyrochlore and co-doped zirconia oxides. The motivation for this work is based on current limitations of the currently

Wesley Francillon

2009-01-01

312

Ethylene oxide potential toxicity.  

PubMed

The future of ethylene oxide (EO) sterilization has been questioned, owing to its associated toxicity. EO has been around for more than 60 years, mainly due to its recognized characteristics of reliability and effectiveness, coupled with the process flexibility, as well as its compatibility with most mechanical devices. Despite the well-known EO toxicity, the undesirable effects of medical devices' EO residues on the patient's health have not yet been well established. There are limitations related to the current risk-assessment studies. To overcome these drawbacks, demands on greater safety are increasing, which lead to improvements in sterilizers and aeration equipment, as well as the design of the processes. The paper under evaluation highlights risks related to EO sterilization of materials used during processing of stem cells for transplantation, but is an example of a study where the dose of the residues in the devices is not considered. PMID:18452382

da Cunha Mendes, Gisela Cristina; da Silva Brandćo, Teresa Ribeiro; Miranda Silva, Cristina Luisa

2008-05-01

313

Oxide Semiconductor Nanowire Biosensors  

NASA Astrophysics Data System (ADS)

Recently, several physics research groups have demonstrated that nanowire field effect transistors (FETs) can function as sensors to detect extremely low concentrations of biological molecules in solution. Continued development and improved understanding of these types of sensors is essential for the emergence of new technologies in disease diagnostics, drug screening, and the single molecule study of biomolecular reactions, to name only a few areas. Currently, the ability to directly and specifically sense molecules in solution would be groundbreaking for medicine, allowing real-time sensing to be incorporated into biomedical devices, as well as used in research. This research aims to contribute to an understanding of the functionality of oxide nanowire FETs, and demonstrate their potential for use as biomolecular sensors, aided in low concentration detection by dielectrophoretic concentration of analyte molecules.

Fleming, Stephen; Gao, Xuan

2011-04-01

314

Indium oxide nanostructures  

NASA Astrophysics Data System (ADS)

In this report we review the growth of indium oxide (In2O3) nanostructures, including octahedral nanocrystals (NCs), nanobelts (NBs), nanosheets (NSs), and nanowires (NWs), by hot-wall chemical vapor deposition (HW-CVD). This system is highly controllable, allowing the user to easily access different growth regimes each corresponding to the growth of a different nanostructure by changing growth variables of the HW-CVD system. Hot-wall CVD produces crystalline nanostructures; here we present a survey of microstructural characterizations of the four types of In2O3 nanostructures using transmission- and scanning-electron microscopy. Interestingly, the In2O3 nanostructures have different preferred growth directions: NCs have (111) faces, NBs are predominantly (200), and NWs are predominantly (110). We end the review by discussing the current shortcomings of HW-CVD growth of In2O3 nanostructures.

Cheng, G.; Stern, E.; Guthrie, S.; Reed, M. A.; Klie, R.; Hao, Y.; Meng, G.; Zhang, L.

2006-11-01

315

Oxycodone N-oxide.  

PubMed

The title compound, (5R,9R,13S,14S,17R)-14-hydroxy-3-methoxy-17-methyl-4,5-epoxymorphinan-6-one N-oxide, C(18)H(21)NO(5), has been prepared in a diastereomerically pure form by the reaction of oxycodone with 3-chloroperbenzoic acid and subsequent crystallization of the product from chloroform. The crystal packing shows that the molecule exhibits intramolecular O-H···O [D···A = 2.482 (2) Å] hydrogen bonding. In addition, there are weak intermolecular C-H...O interactions which, along with van der Waals forces, stabilize the structure. The new chiral center at the 17-position is demonstrated to be R. PMID:23124457

Sonar, Vijayakumar N; Parkin, Sean; Crooks, Peter A

2012-10-18

316

Ultra Supercritical Steamside Oxidation  

SciTech Connect

Ultra supercritical (USC) power plants offer the promise of higher efficiencies and lower emissions, which are goals of the U.S. Department of Energy's Advanced Power Systems Initiatives. Most current coal power plants in the U.S. operate at a maximum steam temperature of 538 C. However, new supercritical plants worldwide are being brought into service with steam temperatures of up to 620 C. Current Advanced Power Systems goals include coal generation at 60% efficiency, which require steam temperatures of up to 760 C. This research examines the steamside oxidation of advanced alloys for use in USC systems, with emphasis placed on alloys for high- and intermediate-pressure turbine sections. Initial results of this research are presented.

Holcomb, Gordon R.; Cramer, Stephen D.; Covino, Bernard S., Jr.; Bullard, Sophie J.; Ziomek-Moroz, Malgorzata

2005-01-01

317

Perovskite-Type Oxides  

NASA Astrophysics Data System (ADS)

Redox properties of high-surface-area LaM1-xCuxO3 (M=Mn or Co) perovskites prepared by the citrate method were studied by H2 TPR and O2 TPD techniques. We have found that the reduction of Mn4+ occurs in all La-Mn-Cu perovskites at temperatures lower than that of Co3+ in La-Co-Cu samples. The presence of copper affects the reduction of both Mn4+ and Co3+, increasing the temperature of reduction. Furthermore, Mn-based perovskites with a low Cu substitution (x< 0.4) release a great amount of O2 at high temperature. Catalytic activity toward methane combustion was investigated under diluted conditions (0.4% CH4 and 10% O2, N2 as balance) in the temperature range 673-1073 K using a fixed bed reactor with a space velocity of 40,000 N cm3 h-1 g-1. All samples catalyze methane oxidation in the temperature range 673-773 K, giving complete methane conversion below 1073 K and producing 100% CO2. No deactivation phenomena were observed. Substitution with copper decreases catalytic activity. The higher activity of Mn-based perovskites compared with that of the corresponding Co samples with the same composition was attributed to the stronger oxidative properties of LaM1-xCux O3. An apparent activation energy of 23 kcal mol-1 was evaluated on the basis of a first-order kinetic equation for all samples.

Lisi, Luciana; Bagnasco, Giovanni; Ciambelli, Paolo; de Rossi, Sergio; Porta, Piero; Russo, Gennaro; Turco, Maria

1999-08-01

318

Transparent metal oxide nanowire transistors  

NASA Astrophysics Data System (ADS)

With the features of high mobility, a high electric on/off ratio and excellent transparency, metal oxide nanowires are excellent candidates for transparent thin-film transistors, which is one of the key technologies to realize transparent electronics. This article provides a comprehensive review of the state-of-the-art research activities that focus on transparent metal oxide nanowire transistors. It begins with the brief introduction to the synthetic methods for high quality metal oxide nanowires, and the typical nanowire transfer and printing techniques with emphasis on the simple contact printing methodology. High performance transparent transistors built on both single nanowires and nanowire thin films are then highlighted. The final section deals with the applications of transparent metal oxide nanowire transistors in the field of transparent displays and concludes with an outlook on the current perspectives and future directions of transparent metal oxide nanowire transistors.

Chen, Di; Liu, Zhe; Liang, Bo; Wang, Xianfu; Shen, Guozhen

2012-05-01

319

Electrodissolution of electrodeposited iron oxides  

SciTech Connect

Galvanostatic reduction of ferric oxide was studied in phosphate solutions over a range of pH values. The oxides were prepared on gold by anodic electrodeposition from dilute ferrous borate solution. With increased pH, the potential of the reduction arrests decreased and the charge associated with the arrest increased. A dependence of -60 mV/pH was observed except between pH 7.5 and 8.5 where the slope approximated -180 mV/pH. Above pH 7.5 the slope was consistent with the thermodynamic predicted slope of -180 mV/pH expected from reductive dissolution of ferric oxide forming soluble ferrous ions. At higher pH values, a slope of -60 mV/pH has been accounted for by oxide reduction to form a solid lower valent oxide.

Isaacs, H.S.; Ryan, M.P. [Brookhaven National Lab., Upton, NY (United States); Kalonousky, D.N. [State Univ. of New York, Stony Brook, NY (United States). Dept. of Materials Science; Virtanen, S. [Swiss Federal Inst. of Tech., Zurich (Switzerland). Inst. of Materials Chemistry and Corrosion

1996-12-31

320

Oxidative behavior of hydrocarbon lubricants  

SciTech Connect

A micro-oxidation tester in conjunction with gel permeation chromatography and clay percolation has been used to study the high temperature oxidation of mineral oil lubricants. (A thin film of a mineral oil lubricant on a metal surface thus simulating the piston-ring cylinder conditions of an internal combustion engine). Oxidation studies reveal higher reaction rates for super-refined than for conventionally refined mineral base oils. For a series of conventionally refined paraffinic base oils, the least viscous fluid has the highest rate of oxidation. The products have a high probability of being evaporated rather than contributing to sludge and deposits or their precursors. High-oxidation-rate constants of all base oils studied signify their vulnerability to oxygen attack. A kinetic model describes a parallel-consecutive mechanism.

Cho, L.F.

1982-01-01

321

Studies of catalytic aerobic oxidation with nanostructured amorphous metals, alloys and metal oxides  

Microsoft Academic Search

The oxidation of cyclohexane with molecular oxygen in the presence of isobutyraldehyde catalyzed by nanostructured iron and cobalt oxides and iron oxide supported on titania has been studied. It was found that highly dispersed transi- tion metal oxide is more effective for oxidation than the corresponding zero-valent metal powders. Nanostructured cobalt oxide on MCM-41 is found to be efficient for

J. Indian; V. K ESAVANa; D. DHAR; Y. KOLTYPIN; N. PERKAS; A. GEDANKEN; S. CHANDRASEKARAN

322

Iron oxide surface catalyzed oxidation of quinoline by hydrogen peroxide  

SciTech Connect

The objective of this research was to examine and compare the surface catalyzed loss of quinoline, a model pollutant, in the presence of three iron oxides: ferrihydrite, goethite, and a semicrystalline iron oxide. These are ubiquitous in the subsurface environment and have been implicated in the possible abiotic loss of contaminants when hydrogen peroxide is injected for augmenting bioremediation. This suggests the possible use of hydrogen peroxide specifically as an oxidant of some compounds in the subsurface. A comparison also reveals the best candidate for use in a supported oxide fixed bed treatment system utilizing hydrogen peroxide as an oxidant. The catalytic activity toward quinoline oxidation was highest for goethite, much less for the semicrystalline material, and negligible in the presence of ferrihydrite. Several water constituents affected reaction rates and stoichiometry by adsorption or through effects on solution chemistry. The stoichiometric efficiency relating quinoline loss to hydrogen peroxide decomposition was not a function of oxide concentration, nor was it affected by the presence of carbonate or phosphate that reduced the rate of hydrogen peroxide decomposition. The effect of humic acid on quinoline loss and hydrogen peroxide decomposition rate depended on its concentration, suggesting that it may act as a radical scavenger, radical chain promoter, and catalytic site inhibitor.

Valentine, R.L.; Wang, H.C.A. [Univ. of Iowa, Iowa City, IA (United States). Dept. of Civil and Environmental Engineering

1998-01-01

323

Oxidation kinetics of sedimentary pyrite in seawater  

SciTech Connect

Long-term (weeks to months) experiments were conducted on the oxidation kinetics of sedimentary pyrite in which initially anoxic sediments containing pyrite were suspended in seawater that was kept in equilibrium with the atmosphere. During an initial reaction period the oxidation of pyrite is relatively rapid, with 3% to 18% oxidation occurring in one day. Calculations indicate that this initial rapid rate of oxidation is the result of the oxidation of very fine (<0.3 {mu}m) pyrite. Following this initial period of rapid oxidation, the oxidation rate slows, with about 20% oxidation typically occurring during the first week. Only a few percent more of the pyrite is oxidized over months of reaction time. Framboidal pyrite is likely to dominate in this period of oxidation and iron oxide or other coatings may significantly inhibit oxidation kinetics. These results indicate that suspended pyrite can persist in oxic seawater for long periods of time and, consequently, be transported substantial distances.

Morse, J.W. (Texas A and M Univ., College Station (United States))

1991-12-01

324

21 CFR 73.3125 - Iron oxides.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Iron oxides. 73.3125 Section 73.3125...CERTIFICATION Medical Devices Ā§ 73.3125 Iron oxides. (a) Identity and specifications. The color additive iron oxides (CAS Reg. No....

2013-04-01

325

Effects of Photochemical Oxidants on Plants.  

National Technical Information Service (NTIS)

Photochemical oxidants are found in 'photochemical smog' which is a complex mixture of primary and secondary air pollutants. The photochemical oxidants are secondary air pollutants formed by the action of sunlight on nitrogen oxides and reactive hydrocarb...

R. Guderian D. T. Tingey R. Rabe

1984-01-01

326

Pomegranate juice protects nitric oxide against oxidative destruction and enhances the biological actions of nitric oxide  

Microsoft Academic Search

Pomegranate juice (PJ), which is a rich source of potent flavonoid antioxidants, was tested for its capacity to protect nitric oxide (NO) against oxidative destruction and enhance the biological actions of NO. Employing chemiluminescence headspace analysis, PJ was found to be a potent inhibitor of superoxide anion-mediated disappearance of NO. PJ was much more potent than Concord grape juice, blueberry

Louis J. Ignarro; Russell E. Byrns; Daigo Sumi; Filomena de Nigris; Claudio Napoli

2006-01-01

327

Oxidation of enrofloxacin with conductive-diamond electrochemical oxidation, ozonation and Fenton oxidation. A comparison  

Microsoft Academic Search

The treatment of enrofloxacin synthetic wastewaters using conductive-diamond electrochemical oxidation (CDEO), ozonation and Fenton oxidation has been studied. Results show that the three technologies can reduce the organic content of enrofloxacin synthetic wastewaters but with different performances. CDEO was the most efficient technology in terms of mineralization but not on COD removal, which was more efficiently achieved by ozonation. This

Elena Guinea; Enric Brillas; Francesc Centellas; Pablo Cańizares; Manuel A. Rodrigo; Cristina Sįez

2009-01-01

328

Oxidative removal of aqueous steroid estrogens by manganese oxides  

Microsoft Academic Search

This study investigated the oxidative removal of steroid estrogens from water by synthetic manganese oxide (MnO2) and the factors influencing the reactions. Using 1×10?5M MnO2 at pH 4, estrone (E1), 17?-estradiol (E2), estriol (E3) and 17?-ethinylestradiol (EE2), all at 4×10?6M, were rapidly removed within 220min, indicating the effectiveness of MnO2 as an oxidizing agent towards estrogens. E2 removal increased with

Lei Xu; Chao Xu; Meirong Zhao; Yuping Qiu; G. Daniel Sheng

2008-01-01

329

Uranium Metal to Oxide Conversion by Air Oxidation ?Process Development  

SciTech Connect

Published technical information for the process of metal-to-oxide conversion of uranium components has been reviewed and summarized for the purpose of supporting critical decisions for new processes and facilities for the Y-12 National Security Complex. The science of uranium oxidation under low, intermediate, and high temperature conditions is reviewed. A process and system concept is outlined and process parameters identified for uranium oxide production rates. Recommendations for additional investigations to support a conceptual design of a new facility are outlined.

Duncan, A

2001-12-31

330

High-temperature oxidation of copper  

NASA Astrophysics Data System (ADS)

Data on the kinetics and thermodynamics of high-temperature oxidation of copper are generalized. The attention is focused on the catastrophic oxidation of copper contacting some low-melting oxides. The results of experimental and theoretical studies of the last 10 years concerning the catastrophic oxidation of copper are analyzed. The theory of catastrophic oxidation of copper under a thin layer of low-melting oxide is considered. The bibliography includes 135 references.

Belousov, Valerii V.; Klimashin, A. A.

2013-03-01

331

How thick is my oxide?  

NASA Astrophysics Data System (ADS)

After a thin film is deposited it is frequently removed from the deposition system exposing it to air on its top surface. It is then subject to oxidation. How thick is the oxide on this sample? This is a question that the technologist who prepared the film is frequently asked, sooner or later after she has taken the film out, particularly when it is to be used in an application for which the presence of an oxide layer even an ultrathin one is important. Our EUV optics deposition group labors in an area where the thickness of ultrathin post deposition films is extremely important. We have looked for a single or set of papers which would help us answer this question for materials of interest for the extreme ultraviolet (EUV or XUV) community. Since they could not be found exist we studied the oxidation of a variety of ultrathin metal films including Al, Cr, Ru, Sc, U, and W using spectroscopic ellipsometry, AFM and low angle x-ray diffraction. We will discuss our progress in understanding the initial stages of oxidation, the optical properties of thin oxides in the EUV. We will discuss the use of EUV reflectance to measure the thickness of ultrathin oxide films.

Allred, David; Squires, Matthew; Newey, Michael; Markos, Douglas; Acosta, Guillermo; Johnson, Cort

2001-03-01

332

Oxidized magnetosomes in magnetotactic bacteria  

NASA Astrophysics Data System (ADS)

Single domain magnetite particles formed in chain assemblies by magnetotactic bacteria (MTB) are taken as proxy in inferring environmental and Earth's magnetism. The reliable use of magnetosomes in MTB, or their fossil remains (magnetofossils), requires that they are unaffected by oxidation. Here we present experimental data from saturation isothermal remanent magnetization (SIRM) and ferromagnetic resonance spectroscopy (FMR) between room temperature and 10 K, which were applied to detect oxidation in intact MTB. The distinction of non-oxidized from oxidized MTB-assemblies is based mainly on two different characteristic physical properties: (i) the intrinsic Verwey transition in pure magnetite, and (ii) blocking of spins of nano-sized products formed during oxidation at the surface or the interior of the magnetosomes. Suppression of the Verwey transition due to oxidation prevents the shift of the anisotropy axes, which in turn conserves the anisotropic properties at room temperature down to low temperature. The presented methodology assures a distinction between non- and oxidized magnetite assemblies, with pronounced certainty, unlike standard dc methods.

Gehring, Andreas U.; Charilaou, Michalis; Garcķa-Rubio, Inés

2012-04-01

333

Urinary Biomarkers of Oxidative Status  

PubMed Central

Oxidative damage produced by reactive oxygen species (ROS) has been implicated in the etiology and pathology of many health conditions, including a large number of chronic diseases. Urinary biomarkers of oxidative status present a great opportunity to study redox balance in human populations. With urinary biomarkers, specimen collection is non-invasive and the organic/metal content is low, which minimizes the artifactual formation of oxidative damage to molecules in specimens. Also, urinary levels of the biomarkers present intergraded indices of redox balance over a longer period of time compared to blood levels. This review summarizes the criteria for evaluation of biomarkers applicable to epidemiological studies and evaluation of several classes of biomarkers that are formed non-enzymatically: oxidative damage to lipids, proteins, DNA, and allantoin, an oxidative product of uric acid. The review considers formation, metabolism, and exertion of each biomarker, available data on validation in animal and clinical models of oxidative stress, analytical approaches, and their intra- and inter-individual variation. The recommended biomarkers for monitoring oxidative status over time are F2-isoprostanes and 8-oxodG. For inter-individual comparisons, F2-isoprostanes are recommended, whereas urinary 8-oxodG levels may be confounded by differences in the DNA repair capacity. Promising urinary biomarkers include allantoin, acrolein-lysine, and dityrosine.

Il'yasova, Dora; Scarbrough, Peter; Spasojevic, Ivan

2012-01-01

334

Mechanism of Bacterial Pyrite Oxidation  

PubMed Central

The oxidation by Ferrobacillus ferrooxidans of untreated pyrite (FeS2) as well as HCl-pretreated pyrite (from which most of the acid-soluble iron species were removed) was studied manometrically. Oxygen uptake was linear during bacterial oxidation of untreated pyrite, whereas with HCl-pretreated pyrite both a decrease in oxygen uptake at 2 hr and nonlinear oxygen consumption were observed. Ferric sulfate added to HCl-pretreated pyrite restored approximately two-thirds of the decrease in total bacterial oxygen uptake and caused oxygen uptake to revert to nearly linear kinetics. Ferric sulfate also oxidized pyrite in the absence of bacteria and O2; recovery of ferric and ferrous ions was in excellent agreement with the reaction Fe2(SO4)3 + FeS2 = 3FeSO4 + 2S, but the elemental sulfur produced was negligible. Neither H2S nor S2O32? was a product of the reaction. It is probable that two mechanisms of bacterial pyrite oxidation operate concurrently: the direct contact mechanism which requires physical contact between bacteria and pyrite particles for biological pyrite oxidation, and the indirect contact mechanism according to which the bacteria oxidize ferrous ions to the ferric state, thereby regenerating the ferric ions required for chemical oxidation of pyrite.

Silverman, Melvin P.

1967-01-01

335

Urinary biomarkers of oxidative status.  

PubMed

Oxidative damage produced by reactive oxygen species (ROS) has been implicated in the etiology and pathology of many health conditions, including a large number of chronic diseases. Urinary biomarkers of oxidative status present a great opportunity to study redox balance in human populations. With urinary biomarkers, specimen collection is non-invasive and the organic/metal content is low, which minimizes the artifactual formation of oxidative damage to molecules in specimens. Also, urinary levels of the biomarkers present intergraded indices of redox balance over a longer period of time compared to blood levels. This review summarizes the criteria for evaluation of biomarkers applicable to epidemiological studies and evaluation of several classes of biomarkers that are formed non-enzymatically: oxidative damage to lipids, proteins, DNA, and allantoin, an oxidative product of uric acid. The review considers formation, metabolism, and exertion of each biomarker, available data on validation in animal and clinical models of oxidative stress, analytical approaches, and their intra- and inter-individual variation. The recommended biomarkers for monitoring oxidative status over time are F?-isoprostanes and 8-oxodG. For inter-individual comparisons, F?-isoprostanes are recommended, whereas urinary 8-oxodG levels may be confounded by differences in the DNA repair capacity. Promising urinary biomarkers include allantoin, acrolein-lysine, and dityrosine. PMID:22683781

Il'yasova, Dora; Scarbrough, Peter; Spasojevic, Ivan

2012-06-07

336

Alumina composites for oxide/oxide fibrous monoliths  

SciTech Connect

Most work on ceramic fibrous monoliths (FMs) has focused on the Si{sub 3}N{sub 4}/BN system. In an effort to develop oxidation-resistant FMs, several oxide systems have recently been examined. Zirconia-toughened alumina and alumina/mullite appear to be good candidates for the cell phase of FMs. These composites offer higher strength and toughness than pure alumina and good high-temperature stability. By combining these oxides, possibly with a weaker high-temperature oxide as the cell-boundary phase, it should be possible to product a strong, resilient FM that exhibits graceful failure. Several material combinations have been examined. Results on FM fabrication and microstructural development are presented.

Cruse, T. A.; Polzin, B. J.; Picciolo, J. J.; Singh, D.; Tsaliagos, R. N.; Goretta, K. C.

2000-03-01

337

Fusion Techniques for the Oxidation of Refractory Actinide Oxides.  

National Technical Information Service (NTIS)

Small-scale experiments were performed to demonstrate the feasibility of fusing refractory actinide oxides with a series of materials commonly used to decompose minerals, glasses, and other refractories as a pretreatment to dissolution and subsequent reco...

T. S. Rudisill

1999-01-01

338

Thermally oxidized zinc oxide nanowires for use as chemical sensors  

NASA Astrophysics Data System (ADS)

Zinc oxide (ZnO) mat-based conductometric devices were fabricated using a thermal oxidation technique. A metallic zinc layer was deposited on the alumina transducer and then oxidized in a controlled atmosphere, in order to obtain ZnO nanostructures. Two different batches of sensors have been prepared, and their sensing performances have been evaluated towards oxidizing and reducing gases. Functional measurements showed very good sensing performances towards ethanol and acetone at 500?° C, and NO2 at 200?° C, indirectly confirming the n-type behaviour of the material. The influence of the humidity on the response has been explored. In practical conditions the interference of humidity is very small, and could be neglected in many applications. Simultaneous measurements on different devices from the same batch confirm the high reproducibility of the response within the batch.

Zappa, D.; Comini, E.; Sberveglieri, G.

2013-11-01

339

Oxidative demethylation of 2-picolines on vanadium oxide catalysts  

SciTech Connect

One of the known methods for the preparation of pyridine is based on the dealkylation of alkylpyridines in the presence of vanadium-containing catalysts, molecular oxygen and steam. By using the oxidative demethylation of 2-picoline in the presence of steam on a fused vanadium(V) oxide, pyridine can be obtained in a yield of up to 88% of theory. To lower the consumption of vanadium(V) oxide and increase the thermostability of the catalyst, they studied the possible use of V/sub 2/O/sub 5/ catalysts on various carriers (diatomite, silica gel, porcelain balls), including the industrially produced brand SVD and SVS catalysts. The SVS brand catalyst has a satisfactory activity and selectivity in the oxidation demethylation of 2-picoline into pyridine. Under optimal conditions, pyridine is formed on this catalyst in a yield of 88% of the theoretical.

Suvorov, B.V.; Glubokovskikh, L.K.; Demin, V.V.; Kan, I.I.

1988-07-10

340

THE FORMATION OF SOLID SOLUTION OXIDES DURING INTERNAL OXIDATION  

SciTech Connect

The diffusion processes occurring when binary alloys react with oxygen to form an oxide that contains both alloy components in solid solution, either exclusively as internal oxide or in combination with a surface scale, have been analyzed and compared with experimental results for Fe-Mn and Ni-Co alloys. The experimental results available for the Fe-Mn system were obtained under conditions of exclusive internal oxidation, and good agreement was obtained between calculated and experimental results. In the Ni-Co system, a surface scale and a zone of internal oxidation develop. Agreement between calculated and experimental depths of internal penetration is acceptable if the diffusivity of oxygen in the alloy is 3.8×10{sup ?6} cm{sup 2}/sec at 1100°C. Agreement between calculated and experimental concentration profiles is not very good.

Whittle, D. P.; Gesmundo, F.; Bastow, B. D.; Wood, G. C.

1980-09-01

341

Oxidative dehydrogenation of isobutane on chromium oxide-based catalyst  

Microsoft Academic Search

Isobutane oxidative dehydrogenation offers a prospect of cheaper and environment friendly route to isobutene. The reaction has been studied at 250°C, 1atm and feed flow rate of 75cm3\\/min over supported chromium oxide-based catalysts. Effects of various supports (Al2O3, MgO, TiO2 and SiO2), catalyst precursors (K2Cr2O7, CaCr2O7·H2O, CrO3, CrK(SO4)2·12H2O and Cr(NO3)3·9H2O) and binary mixed metal oxide catalysts of the form Cr-M-oxide\\/?-Al2O3

B. Y. Jibril; N. O. Elbashir; S. M. Al-Zahrani; A. E. Abasaeed

2005-01-01

342

Thermally oxidized zinc oxide nanowires for use as chemical sensors.  

PubMed

Zinc oxide (ZnO) mat-based conductometric devices were fabricated using a thermal oxidation technique. A metallic zinc layer was deposited on the alumina transducer and then oxidized in a controlled atmosphere, in order to obtain ZnO nanostructures. Two different batches of sensors have been prepared, and their sensing performances have been evaluated towards oxidizing and reducing gases. Functional measurements showed very good sensing performances towards ethanol and acetone at 500?° C, and NO2 at 200?° C, indirectly confirming the n-type behaviour of the material. The influence of the humidity on the response has been explored. In practical conditions the interference of humidity is very small, and could be neglected in many applications. Simultaneous measurements on different devices from the same batch confirm the high reproducibility of the response within the batch. PMID:24113169

Zappa, D; Comini, E; Sberveglieri, G

2013-10-10

343

Peroxisomes, oxidative stress, and inflammation  

PubMed Central

Peroxisomes are intracellular organelles mediating a wide variety of biosynthetic and biodegradative reactions. Included among these are the metabolism of hydrogen peroxide and other reactive species, molecules whose levels help define the oxidative state of cells. Loss of oxidative equilibrium in cells of tissues and organs potentiates inflammatory responses which can ultimately trigger human disease. The goal of this article is to review evidence for connections between peroxisome function, oxidative stress, and inflammation in the context of human health and degenerative disease. Dysregulated points in this nexus are identified and potential remedial approaches are presented.

Terlecky, Stanley R; Terlecky, Laura J; Giordano, Courtney R

2012-01-01

344

Partial Oxidation of Isobutane over Vanadium Phosphorus Oxides  

Microsoft Academic Search

A series of vanadium phosphorus oxides (VPO) were prepared by using dodecyl amine as surfactant and tested for the partial\\u000a oxidation of isobutane and isobutene. Characterization results showed that their structure and properties depend on the content\\u000a of dodecyl amine. Catalytic tests showed that relatively high isobutane conversion and desired product selectivity can be\\u000a achieved over a proper dodecyl amine

Jingqi Guan; Zhuqian Wang; Chen Xu; Ying Yang; Bo Liu; Xiaofang Yu; Qiubin Kan

2009-01-01

345

Oxidative coupling of methane over natural manganese oxide  

Microsoft Academic Search

Oxydehydrogenative coupling of methane to higher hydrocarbons has been achieved with high selectivity towards C2 products over natural mineral manganese oxides. Oxide treatments under hydrocarbon atmosphere show that the reduction of manganese ions Mn(IV), Mn(III) to Mn(II) is mainly responsible for the catalyst deactivation. The tests using CH4 + CD4 equimolecular mixtures and the analysis of the (HD)C2 products by

L. M. Ioffe; T. Lopez; Y. G. Borodko; R. Gomez

1995-01-01

346

The interaction of different oxidizing agents on doped tin oxide  

Microsoft Academic Search

The interaction of NO2, NOx and O2 and O2 on an SnO2 thin-film surface is studied. Experiments have been carried out for different tin-oxide films, undoped and doped with Pt, In and Al, prepared by reactive sputtering (r.f.) on alumina substrates. These films should allow the development of detectors for nitrogen oxides at concentrations of about a few ppm. Conductance

I. Sayago; J. Gutie“rrez; L. Are“s; J. I. Robla; M. C. Horrillo; J. Getino; J. A. Agapito

1995-01-01

347

Indirect oxidation effect in electrochemical oxidation treatment of landfill leachate  

Microsoft Academic Search

Treatment of a low BODCOD ratio landfill leachate was conducted by means of electrochemical oxidation process in this investigation. Under the operating conditions of 15 A\\/dm2 current density and 7500 mg\\/l additional chloride concentration, 92% of the COD in the landfall leachate was removed after electrolysis for 240 min with a ternary Sn?Pd?Ru oxide-coated titanium (SPR) anode. At the same

Li-Choung Chiang; Juu-En Chang; Ten-Chin Wen

1995-01-01

348

Fusion Techniques for the Oxidation of Refractory Actinide Oxides  

Microsoft Academic Search

Small-scale experiments were performed to demonstrate the feasibility of fusing refractory actinide oxides with a series of materials commonly used to decompose minerals, glasses, and other refractories as a pretreatment to dissolution and subsequent recovery operations. In these experiments, 1-2 g of plutonium or neptunium oxide (PuO2<\\/sub> or NpO2<\\/sub>) were calcined at 900 degrees Celsius, mixed and heated with the

Rudisill

1999-01-01

349

Anomalous oxidation of ferritic interconnects in solid oxide fuel cells  

Microsoft Academic Search

An anomalous oxide scale formed on Fe–Cr alloy interconnects was investigated under operation conditions for solid oxide fuel cells (SOFCs). A dilute CH4–H2O was flowed one side and air was flowed the other side under constant current flow (0.3Acm-2). The Pt-mesh\\/alloy interface resistance in CH4–H2O increases with reaction time in a parabolic relationship. The diffusion controlled mechanism was proposed for

Teruhisa Horita; Haruo Kshimoto; Katsuhiko Yamaji; Natsuko Sakai; Yuping Xiong; Maunel E. Brito; Harumi Yokokawa

2008-01-01

350

Uncouplers of oxidative phosphorylation.  

PubMed Central

Uncouplers of oxidative phosphorylation in mitochondria inhibit the coupling between the electron transport and phosphorylation reactions and thus inhibit ATP synthesis without affecting the respiratory chain and ATP synthase (H(+)-ATPase). Miscellaneous compounds are known to be uncouplers, but weakly acidic uncouplers are representative because they show very potent activities. The most potent uncouplers discovered so far are the hindered phenol SF 6847, and hydrophobic salicylanilide S-13, which are active in vitro at concentrations in the 10 nM range. For induction of uncoupling, an acid dissociable group, bulky hydrophobic moiety and strong electron-withdrawing group are required. Weakly acidic uncouplers are considered to produce uncoupling by their protonophoric action in the H(+)-impermeable mitochondrial membrane. For exerting these effects, the stability of the respective uncoupler anions in the hydrophobic membrane is very important. High stability is achieved by delocalization of the polar ionic charge through uncoupler (chemical)-specific mechanisms. Such an action of weakly acidic uncouplers is characteristic of the highly efficient membrane targeting action of a nonsite-specific type of bioactive compound.

Terada, H

1990-01-01

351

Partial oxidation process  

SciTech Connect

This patent describes an improvement in a process for the partial oxidation of an ash-containing heavy liquid hydrocarbonaceous fuel, an ash-containing solid carbonaceous fuel, or mixtures thereof to produce an effluent gas stream having a temperature in the range of about 2000{degrees}F to 3000{degrees}F and comprising H{sub 2} + CO and entrained molten slag and ash; and cooling the effluent gas stream by passing the gas stream in succession through a radiant cooling zone, a metal gas transfer line with internal metal heat transfer surfaces, and a convection cooling zone. The improvement involves preventing the molten slag and ash from sticking to the metal heat transfer surfaces on the inside of the gas transfer line comprising: cooling the internal metal heat transfer surfaces of the metal gas transfer line where high gas turbulence occurs to a temperature in the range of about 150{degrees}F to below 700{degrees}F by noncontact heat exchange with a coolant.

Jahnke, F.C.

1989-12-26

352

Catalysts for hydrocarbon oxidation  

SciTech Connect

This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The focus of this project was elucidating structural aspects of a titanosilicate TS-1 that is an oxidation catalyst. The authors have prepared samples of TS-1 and used scanning electron microscopy, high resolution transmission electron microscopy, and ultraviolet-visible spectroscopy to examine the samples of TS-1 for amorphous titanium-containing phases that may confound the analysis of the neutron scattering data. They observed that the volume fraction of titanium-containing impurity phases(s) determined from electron microscopy did not correlate well with that amount determined by ultraviolet-visible diffuse-reflectance spectroscopy. The authors also designed, constructed and tested a flow reactor that can be placed into the neutron flight path at the High Intensity Powder Diffractometer line at the Manual Lujan, Jr. Neutron Scattering Center. This reactor will allow for the observation of crystallographic changes of catalysts and other materials under reaction conditions.

Ott, K.C.; Paffett, M.T.; Earl, W.L. [and others

1998-12-31

353

Nitric oxide nanoparticles  

PubMed Central

Nitric oxide (NO) is a critical component of host defense against invading pathogens; however, its therapeutic utility is limited due to a lack of practical delivery systems. Recently, a NO-releasing nanoparticulate platform (NO-np) was shown to have in vitro broad-spectrum antimicrobial activity and in vivo pre-clinical efficacy in a dermal abscess model. To extend these findings, both topical (TP) and intralesional (IL) NO-np administration was evaluated in a MRSA intramuscular murine abscess model and compared with vancomycin. All treatment arms accelerated abscess clearance clinically, histologically, and by microbiological assays on both days 4 and 7 following infection. However, abscesses treated with NO-np via either route demonstrated a more substantial, statistically significant decrease in bacterial survival based on colony forming unit assays and histologically revealed less inflammatory cell infiltration and preserved muscular architecture. These data suggest that the NO-np may be an effective addition to our armament for deep soft tissue infections.

Schairer, David O.; Martinez, Luis R.; Blecher, Karin; Chouake, Jason S.; Nacharaju, Parimala; Gialanella, Philip; Friedman, Joel M.; Nosanchuk, Joshua D.; Friedman, Adam J.

2012-01-01

354

Catastrophic Oxidation of Copper: A Brief Review  

NASA Astrophysics Data System (ADS)

A brief review of the current understanding of copper accelerated oxidation in the presence of low-melting oxides (Bi2O3, MoO3, and V2O5) is given. Special attention is paid to the kinetics, thermodynamics, and mechanisms of accelerated oxidation of copper. The mechanisms of two stages (fast and superfast) of the copper accelerated oxidation are considered. It is shown that the fast oxidation of copper occurs by a diffusion mechanism. Oxygen diffusion along the liquid channels in the oxide scale is the rate-limiting step in the overall mechanism. The superfast oxidation of copper occurs by a fluxing mechanism. Realization of the particular mechanism depends on the mass ratio of low-melting oxide to the metal. The mass ratios of low-melting oxide to the metal and the oxygen partial pressures for superfast oxidation of copper are established. A model of the fast oxidation of copper is discussed.

Belousov, V. V.; Klimashin, A. A.

2012-10-01

355

Process for removing sulfur oxide and nitrogen oxide  

SciTech Connect

This patent describes a process for reducing at least one of (1) the sulfur oxide content of a sulfur oxide-containing gas and (2) the nitrogen oxide content of a nitrogen oxide-containing gs which includes contacting the gas with a material at conditions to reduce at least one of (1) the sulfur oxide content of the gas and (2) the nitrogen oxide of the gas, the improvement comprising utilizing as at least a portion of the material the spinel/clay composition produced in accordance with the process comprising: (a) combining (1) an acidic, aluminum-containing composition in which the aluminum is present in a positively charged species, and (2) a basic alkaline earth metal-containing composition to form a gel mixture; and (b) mixing the gel with kaolin clay to form a co-gel mixture; and (c) calcinating the co-gel mixture to form the alkaline earth metal, aluminum-containing spinel composition, in a kaolin clay matrix.

Bhattacharyya, A

1989-05-16

356

Structure, adhesion, and stability of metal/oxide and oxide/oxide interfaces  

SciTech Connect

Studies of structural, electronic, and chemical properties of metal/oxide and oxide/oxide interfaces were performed on well-defined interfaces that created by depositing ultra-thin potassium and aluminum films and their oxides onto single crystal TiO[sub 2] and NiO surfaces. Work focused on determining the structure, growth mechanisms, and morphologies of metal and oxide films as they are deposited an single crystal oxide surfaces using RHEED and atomic force microscopy probing electronic structure, bonding and chemical interactions at the interfaces using x-ray and uv photoelectron spectroscopies (XPS, UPS) and Auger electron spectroscopy (AES), and understanding factors affecting stability and reactivity of the interface regions including the role of defects and impurities. Results indicate that kinetic effects have an important influence on interface structure and composition, and they also show that defects in the oxide substrate induce new electronic states at the interface which play a major role in cation-anion bonding and interface interactions. The results establish a link between electronic and chemical bonding properties and the interface structure and morphology, which is required to successfully manipulate the interfacial properties of advanced ceramic materials.

Lad, R.J.

1992-11-01

357

Cr(III) oxidation coupled with Mn(II) bacterial oxidation in the environment  

Microsoft Academic Search

Purpose  Cr(III) oxidation to Cr(VI) significantly increases Cr mobility and toxicity and thus its environmental risks. Manganese (Mn)\\u000a oxides may serve as the potential oxidants of Cr(III) in environment. Natural Mn oxides in the environment are believed to\\u000a be derived from bacterial oxidation. The objective of this study was to examine the Cr(III) oxidation capacity of biogenic\\u000a Mn oxide and the

Ji-Zheng He; You-Ting Meng; Yuan-Ming Zheng; Li-Mei Zhang

2010-01-01

358

Oxides having high energy densities  

DOEpatents

Certain disclosed embodiments generally relate to oxide materials having relatively high energy and/or power densities. Various aspects of the embodiments are directed to oxide materials having a structure B.sub.i(M.sub.jY.sub.k)O.sub.2, for example, a structure Li.sub.j(Ni.sub.jY.sub.k)O.sub.2 such as Li(Ni.sub.0.5Mn.sub.0.5)O.sub.2. In this structure, Y represents one or more atoms, each independently selected from the group consisting of alkaline earth metals, transition metals, Group 14 elements, Group 15, or Group 16 elements. In some embodiments, such an oxide material may have an O3 crystal structure, and/or a layered structure such that the oxide comprises a plurality of first, repeating atomic planes comprising Li, and a plurality of second, repeating atomic planes comprising Ni and/or Y.

Ceder, Gerbrand; Kang, Kisuk

2013-09-10

359

Oil agglomeration of oxidized coal  

SciTech Connect

The effect of surface oxidation on the oil agglomeration characteristics of coal has not been well documented, although it is known that lower rank, hydrophilic coals are more difficult to agglomerate than higher rank, hydrophobic coals. In order to contribute to a better understanding of the effect of surface oxidation, the present investigation was undertaken. Upper Freeport bituminous coal from Pennsylvania was selected for the study because it is normally hydrophobic and readily agglomerated. A surface oxidation treatment was applied to this coal to see how it would affect the agglomeration characteristics of the material. In determining these characteristics, samples of oxidized and unoxidized coal fines were suspended in water and agglomerated with pure aliphatic hydrocarbons. Both the pH of the suspension and amount of added oil were varied, and in some cases various surfactants were added to the suspension. The electrokinetic properties of the coal particles and oil droplets were also determined to gain further insight. 12 refs., 10 figs.

Sadowski, Z.; Venkatadri, R.; Druding, J.M.; Markuszewski, R.; Wheelock, T.D.

1986-01-01

360

Polaron Morphologies in Vanadium Oxides.  

National Technical Information Service (NTIS)

The conditions when oxides containing octahedral-site vanadium ions form partially filled, narrow d-like bands are described. Electronphonon interactions may transform such narrow bands into molecular orbitals, giving rise to semiconductor-to-metal transi...

J. B. Goodenough

1971-01-01

361

FLUORINATION OF OXIDIC NUCLEAR FUEL  

DOEpatents

A process of volatilizing fissionable material away from fission products, present together in neutron-bombarded uranium oxide, by reaction with an oxygen-fluorine mixture at 350 to 500 deg C is described. (AEC)

Mecham, W.J.; Gabor, J.D.

1963-07-23

362

Kinetic Study on Polyphenylene Oxide.  

National Technical Information Service (NTIS)

The Arrhenius activation energy and reaction rate constants for polyphenylene oxide (PPO), both unfilled and filled with 30-percent glass fiber, were determined by isothermal and by temperature programmed thermogravimetric (TGA) methods and found to be 45...

R. J. Katzenstein

1970-01-01

363

Aluminum Castings for Anodic Oxidation.  

National Technical Information Service (NTIS)

The significance of the manufacture of decorative anodically oxidized aluminum castings is demonstrated by means of examples, and alloys suitable for this are enumerated. Then dealt with are errors of casting and melting technique which become apparent wi...

A. A. Bloch

1966-01-01

364

A zinc oxide microwire laser  

Microsoft Academic Search

In this paper, we report stimulated emission from a zinc oxide (ZnO) microcrystal grown by carbothermal evaporation observed by spatially resolved photoluminescence (PL) and high excitation spectroscopy (HES).

C. Czekalla; J. Lenzner; A. Rahm; T. Nobis; M. Grundmann

2007-01-01

365

A zinc oxide microwire laser  

NASA Astrophysics Data System (ADS)

In this paper, we report stimulated emission from a zinc oxide (ZnO) microcrystal grown by carbothermal evaporation observed by spatially resolved photoluminescence (PL) and high excitation spectroscopy (HES).

Czekalla, C.; Lenzner, J.; Rahm, A.; Nobis, T.; Grundmann, M.

2007-05-01

366

Cathodoluminescence of uranium oxides*1  

Microsoft Academic Search

The cathodoluminescence of uranium oxide surfaces prepared in-situ from clean uranium exposed to dry oxygen was studied. The broad asymmetric peak observed at 470 nm is attributed to F-center excitation.

K. Winer; C. Colmenares; F. Wooten

1984-01-01

367

Advanced Photochemical Oxidation Processes. Handbook.  

National Technical Information Service (NTIS)

This handbook discusses the applicability of advanced photochemical oxidation (APO) technologies for treatment of contaminated water, air, and solids (soil, sediment, and ash). The primary purpose of this handbook is to summarize commercial-scale APO syst...

K. Topudurtir S. Tay E. Monschein

1998-01-01

368

Transparent, Polycrystalline Cubic Aluminum Oxide.  

National Technical Information Service (NTIS)

The stringent mechanical/thermal and broadband electromagnetic wave transmission requirements for sensing mechanisms of the future require optimized and new material concepts. Aluminum oxide-based ceramics and single crystals are strong contenders for the...

J. W. McCauley N. D. Corbin

1980-01-01

369

Fluorescence from Coated Oxide Nanoparticles.  

National Technical Information Service (NTIS)

In many cases, coated nanoparticles behave like isolated ones. Using the microwave plasma process, it is possible to produce oxide nanoparticles with ceramic or polymer coating. Coating the particles has the additional advantage that by proper selection o...

D. Vollath D. V. Szabo I. Lamparth

2001-01-01

370

Study of Adherent Oxide Formation.  

National Technical Information Service (NTIS)

The effects by which minor element additives (yttrium and hafnium) and laser surface melting and rapid solidification (laser-processing) improve oxide scale adherence to NiCrAl were investigated. Laser-processed materials were isothermally and cyclically ...

A. W. Funkenbusch J. G. Smeggil

1983-01-01

371

ENGINEERING BULLETIN: SUPERCRITICAL WATER OXIDATION  

EPA Science Inventory

This engineering bulletin presents a description and status of supercritical water oxidation technology, a summary of recent performance tests, and the current applicability of this emerging technology. This information is provided to assist remedial project managers, contractors...

372

ENGINEERING BULLETIN: SUPERCRITICAL WATER OXIDATION  

EPA Science Inventory

This engineering bulletin presents a description and status of supercritical water oxidation technology, a summary of recent performance tests, and the current applicability of this emerging technology. his information is provided to assist remedial project managers, contractors ...

373

Oxidative Damage in Parkinson's Disease.  

National Technical Information Service (NTIS)

The objective of the present research is to determine whether there is a coherent body of evidence implicating oxidative damage in the pathogenesis of Parkinson's Disease and the MPTP model of Parkinsonism. We found that there are significant decreases in...

M. F. Beal

2000-01-01

374

Electrochemical Oxidation of Saturated Hydrocarbons.  

National Technical Information Service (NTIS)

A study was undertaken to define and analyze the factors controlling the catalytic activity of platinum black toward the anodic oxidation of saturated hydrocarbons. The objective was to develop a correlation between the physical characteristics of a black...

J. Giner J. M. Parry

1967-01-01

375

Oxidation at intermediate moisture contents  

Microsoft Academic Search

In the study of the oxidation rate of methyl linoleate in protein and cellulose systems, a prooxidant effect was found at\\u000a intermediate moisture contents. At low water content, water hydrates metals and hydrogen bonds with peroxides, and an overall\\u000a decrease in the rate of lipid oxidation results. With an increase in the water content to the region with a water

T. P. Labuza; N. D. Heidelbaugh; M. Silver; M. Karel

1971-01-01

376

Oxidative Stress and Cardiovascular Fibrosis  

Microsoft Academic Search

\\u000a Oxidative stress is defined as an imbalance of the generation of reactive oxygen species (ROS) in excess of the capacity of\\u000a cells\\/tissues to detoxify or scavenge them. Such a state of oxidative stress may alter the structure\\/function of cellular\\u000a macromolecules that eventually leads to tissue\\/organ dysfunction. The harmful effects of ROS have been largely attributed\\u000a to its indiscriminate, stochastic effects

Subramaniam Pennathur; Louise Hecker; Victor J. Thannickal

377

High surface area tin oxide  

Microsoft Academic Search

High surface area tin oxides are desirable catalyst carriers for emissions control including CO oxidation, VOC removal\\/methane combustion and NOx abatement. We have optimized literature procedures as well as developed proprietary recipes for the synthesis of porous SnO2 carriers. Precipitation of SnCl4 from homogeneous solution by urea and by hydrazine, the dissolution of Sn metal powder in HNO3, sol–gel routes

Alfred Hagemeyer; Zach Hogan; Marco Schlichter; Birgit Smaka; Guido Streukens; Howard Turner; Anthony Volpe Jr.; Henry Weinberg; Karin Yaccato

2007-01-01

378

Anodic Oxidation of Zinc Phosphide  

Microsoft Academic Search

Initial stages of a native oxidation on Zn3P2 by anodization have been investigated for the first time using 3% tartaric acid\\/propylene glycol electrolyte. A constant-current anodization is found to be superior to a constant-voltage anodization because of the rapid growth of the initial stage in the constant-voltage mode in view of controlling thin oxide layers. The surface composition of anodized

Toshikazu Suda; Yoshitada Murata; Shoichi Kurita

1986-01-01

379

Signal Transduction by Mitochondrial Oxidants*  

PubMed Central

The production of mitochondrial reactive oxygen species occurs as a consequence of aerobic metabolism. Mitochondrial oxidants are increasingly viewed less as byproducts of metabolism and more as important signaling molecules. Here, I review several notable examples, including the cellular response to hypoxia, aspects of innate immunity, the regulation of autophagy, and stem cell self-renewal capacity, where evidence suggests an important regulatory role for mitochondrial oxidants.

Finkel, Toren

2012-01-01

380

The oxidation of organic compounds  

Microsoft Academic Search

In a study of the behavior of tris(hydroxymethyl)-4-picoline (I) under the conditions of vapor-phase oxidation on a vanadium-tin oxide catalyst, it was found that with the addition of 150–250 mole of water and 125–200 mole of O2 per mole of I and a contact time of 0.35–0.45 sec, the main reaction product was isonicotinic acid (II), the yield of which

T. A. Afanas'eva; A. D. Kagarlitskii; B. V. Suvorov

1970-01-01

381

Enzymes of respiratory iron oxidation  

SciTech Connect

This report describes experimental progress in characterizing and identifying redox proteins in a number of iron-oxidizing bacteria. Sections of the paper are entitled (1) In Situ electrolysis was explored to achieve enhanced yields of iron-oxidizing bacteria, (2)Structure/function studies were performed on redox-active biomolecules from Thiobacillus ferrooxidans, (3) Novel redox-active biomolecules were demonstrated in other iron autotrophs, and (4) New probes of metalloprotein electron-transfer reactions were synthesized and characterized.

Blake, R. II.

1992-01-01

382

Oxidation and sulfonation of cellulosics  

Microsoft Academic Search

Bleached hardwood (HW) kraft pulp and derived nanocellulosic structures were modified by a periodate oxidation followed by\\u000a treatment with sodium bisulfite to yield the corresponding C2\\/3 sulfonates. The impact of this oxidative–reductive protocol\\u000a on the chemical and physical properties of cellulose was evaluated by determining physical dimensions, functional groups,\\u000a and their water absorbency properties. It was found that the water

Jianguo Zhang; Nan Jiang; Zheng Dang; Thomas J. Elder; Arthur J. Ragauskas

2008-01-01

383

Oxidation of Hastelloy C276  

Microsoft Academic Search

Oxidation of Hastelloy C276 was studied at 300-800 °C in atmospheres that ranged from 0.01 to 100% O2. X-ray diffraction and scanning electron microscopy indicated formation of Cr2O3 scales. The oxidation kinetics were approximately parabolic, but, contrary to expectations, there was no clear trend of scale-growth kinetics vs. oxygen partial pressure. This anomalous response was attributed to an extrinsic effect

J.-H. Park; L. Chen; K. C. Goretta; R. E. Koritala; U. Balachandran

2002-01-01

384

Oxidation of Hastelloy C276  

Microsoft Academic Search

Oxidation of Hastelloy C276 was studied at 300–800 °C in atmospheres that ranged from 0.01 to 100% O2. X-ray diffraction and scanning electron microscopy indicated formation of Cr2O3 scales. The oxidation kinetics were approximately parabolic, but, contrary to expectations, there was no clear trend of scale-growth kinetics vs. oxygen partial pressure. This anomalous response was attributed to an extrinsic effect

J.-H. Park; L. Chen; K. C. Goretta; R. E. Koritala; U. Balachandran

2002-01-01

385

Oxidation behavior of titanium aluminides  

Microsoft Academic Search

Results from an ongoing study of the high temperature oxidation of intermetallic compounds in the Ti-Al system are presented. The oxidation behavior of alloys based on TiAl (y) has been found to be extremely complex depending on temperature and atmosphere composi- tion. Protective alumina scales are formed in pure O2 up to a critical temperature above which a mixed Ti02\\/A1203

F. S. Pettit; S. HU

1993-01-01

386

Oxidation of Amines by Flavoproteins  

PubMed Central

Many flavoproteins catalyze the oxidation of primary and secondary amines, with the transfer of a hydride equivalent from a carbon -nitrogen bond to the flavin cofactor. Most of these amine oxidases can be classified into two structural families, the D -amino acid oxidase/sarcosine oxidase family and the monoamine oxidase family. This review discusses the present understanding of the mechanisms of amine and amino acid oxidation by flavoproteins, focusing on these two structural families.

Fitzpatrick, Paul F.

2009-01-01

387

Nitric oxide synthases and osteoarthritis  

Microsoft Academic Search

The production of nitric oxide (NO) by chondrocytes is increased in human osteoarthritis. The excessive production of NO inhibits\\u000a matrix synthesis and promotes its degradation. Furthermore, by reacting with oxidants such as superoxide anion, NO promotes\\u000a cellular injury and renders the chondrocyte susceptible to cytokine-induced apoptosis. Thus, NO produced by activated chondrocytes\\u000a in diseased cartilage may modulate disease progression in

Jose U. Scher; Michael H. Pillinger; Steven B. Abramson

2007-01-01

388

Oxidation behavior of aluminum nanopowders  

SciTech Connect

Rutherford backscattering spectrometry, thermogravimetric analysis, and high-resolution transmission electron microscopy were used to investigate the oxidation behavior of ultrafine grain aluminum powder. Fractional change in mass of Al powder samples were obtained as a function of temperature and exposure time for samples with different particle size distributions. Activation energy for oxidation is found to depend on average Al particle size and to be much smaller than that known for flat Al samples.

Aumann, C.E.; Skofronick, G.L.; Martin, J.A. [Los Alamos National Lab., NM (United States). Chemical Science and Technology Div.

1994-11-01

389

Enzymes of respiratory iron oxidation  

Microsoft Academic Search

This report describes experimental progress in characterizing and identifying redox proteins in a number of iron-oxidizing bacteria. Sections of the paper are entitled (1) In Situ electrolysis was explored to achieve enhanced yields of iron-oxidizing bacteria, (2)Structure\\/function studies were performed on redox-active biomolecules from Thiobacillus ferrooxidans, (3) Novel redox-active biomolecules were demonstrated in other iron autotrophs, and (4) New probes

Blake; R. II

1992-01-01

390

Millisecond Oxidation of Alkanes  

SciTech Connect

This project was undertaken in response to the Department of Energy's call to research and develop technologies 'that will reduce energy consumption, enhance economic competitiveness, and reduce environmental impacts of the domestic chemical industry.' The current technology at the time for producing 140 billion pounds per year of propylene from naphtha and Liquified Petroleum Gas (LPG) relied on energy- and capital-intensive steam crackers and Fluidized Catalytic Cracking (FCC) units. The propylene is isolated from the product stream in a costly separation step and subsequently converted to acrylic acid and other derivatives in separate production facilities. This project proposed a Short Contact Time Reactor (SCTR)-based catalytic oxydehydrogenation process that could convert propane to propylene and acrylic acid in a cost-effective and energy-efficient fashion. Full implementation of this technology could lead to sizeable energy, economic and environmental benefits for the U. S. chemical industry by providing up to 45 trillion BTUs/year, cost savings of $1.8 billion/year and a combined 35 million pounds/year reduction in environmental pollutants such as COx, NOx, and SOx. Midway through the project term, the program directive changed, which approval from the DOE and its review panel, from direct propane oxidation to acrylic acid at millisecond contact times to a two-step process for making acrylic acid from propane. The first step was the primary focus, namely the conversion of propane to propylene in high yields assisted by the presence of CO2. The product stream from step one was then to be fed directly into a commercially practiced propylene-to-acrylic acid tandem reactor system.

Scott Han

2011-09-30

391

Nitric oxide synthase in invertebrates.  

PubMed

The gas nitric oxide is now recognized as an important signalling molecule that is synthesized from L-arginine by the enzyme nitric oxide synthase. This enzyme can be localized by different methods, including immunocytochemistry and the histochemical reaction for NADPH diaphorase. It has been demonstrated in various vertebrate cells and tissues, and recently several studies dealing with the production of nitric oxide in invertebrates have been published. Diploblastic animals, flatworms and nematodes seem to lack NADPH diaphorase activity but it has been found in the rest of the phyla studied. The most frequently reported sites for the production of nitric oxide are the central and peripheral nervous systems and, in primitive molluscs, the muscle cells. In insects, it has also been described in the Malpighian tubules. The roles of nitric oxide in invertebrates are closely related to the physiological actions described in vertebrates, namely, neurotransmission, defence, and salt and water balance. The recent cloning of the first nitric oxide synthase from an invertebrate source could open interesting avenues for further studies. PMID:8575940

Martķnez, A

1995-10-01

392

Metal Oxides in the Environment  

SciTech Connect

Oxides are ubiquitous in much of environmental chemistry. Silica and related glasses are potential vehicles by which radioactive elements may be sequestered and stored. The migration of toxic waste in ground water is largely influenced by interactions at the liquid-solid interface, with several metal oxides making up the bulk of soil. In addition, metal oxides with Bronsted acid or Lewis base functionality are potential replacements for many traditional liquid catalysis that are hazardous to work with and difficult to dispose. In this proposal, we targeted two such areas of oxide chemistry. The long-term behavior of silicate materials slated for use in the entombment of high-level waste (HLW), and the use of solid acid metal oxides as replacements for toxic sulfuric and hydrofluoric acid used in industry (referred to as Green Chemistry). Thus, this project encompassed technology that can be used to both remediate and prevent pollution. These oxide systems were studied using density functional theory (DFT). The comparatively large size and complexity of the systems that will bweree studied made use of high-accuracy electronic structure studies intractable on conventional computers. The 512 node parallel processor housed in the Molecular Science Computing Facility (MSCF) provided the required capability.

Jonsson, Hannes; Corrales, L. Rene; Gabriel, Peggy; Haw, James F.; Henkelman, Graeme A.; Neurock, Matthew; Nicholas, John B.; Park, Byeongwon; Song, Jakyoung; Trout, Bernhardt; Tsemekhman, Kiril L.; Uberuaga, Blas P.; Van Ginhoven, Renee M.

2002-08-30

393

Mechanism of carrier transport through a silicon-oxide layer for ?indium-tin-oxide\\/silicon-oxide\\/silicon? solar cells  

Microsoft Academic Search

The mechanism of carrier transport through a thin silicon-oxide layer for ?spray-deposited indium-tin-oxide (ITO)\\/silicon-oxide\\/Si? solar cells has been studied by measurements of the dark current density as a function of the thickness of the silicon-oxide layer, together with the observation of transmission electron micrographs. Cross-sectional transmission electron micrography shows that a uniform silicon-oxide layer with the thickness of ?2 nm

H. Kobayashi; T. Ishida; Y. Nakato; H. Mori

1995-01-01

394

Mechanism of internal oxidation in silver alloys  

Microsoft Academic Search

The internal oxidation mechanism in silver alloys was studied by residual resistivity, gravimetric, and calorimetric measurements, and by transmission electron microscopy. If the flux, of oxygen atoms is very large with respect to the oxide formation, the mechanism of internal oxidation includes two stages. The first one is the fixation of oxygen in the form of oxidized elementary species, including

A. Combe; J. Cabane

1984-01-01

395

Volatile compounds of oxidized cocoa butter  

Microsoft Academic Search

To evaluate the oxidative behavior of cocoa butter, the autoxidation of refined and non-refined butter samples was accelerated (oxidized at day light at room temperature and at 90 °C). The quantity of certain aldehydes formed during the oxidation of cocoa butter was examined by gas chromatography. The oxidation stability of butter was evaluated over a 12-week period. The influence of

L. Hashim; S. Hudiyono; H. Chaveron

1997-01-01

396

Temperature Programmed Desorption Study of Graphene Oxide  

Microsoft Academic Search

Graphene oxide is an electrical insulator that shows potential for use in nanoscale electronic devices. An understanding of the thermal stability of graphene oxide sheets is important since the electrical, chemical, and mechanical properties of graphene oxide will change as it is reduced at elevated temperatures. In this study, graphene oxide films were grown by deposition of an aqueous solution

Nicholas Clark; Daniel Field; Simona Rieman; Carl Ventrice; Inhwa Jung; Dongxing Yang; Richard Piner; Rodney Ruoff

2009-01-01

397

Oxidants, antioxidant nutrients and the athlete  

Microsoft Academic Search

Strenuous physical exercise induces oxidative stress. There may be a number of sources of this oxidative stress, including mitochondrial superoxide production, ischaemia-reperfusion mechanisms and auto-oxidation of catecholamines. Severe or prolonged exercise can overwhelm antioxidant defences, which include vitamins E and C and thiol antioxidants, which are interlinked in an antioxidant network, as well as antioxidant enzymes. Evidence for oxidative stress

L. Packer

1997-01-01

398

Sacrificial oxide etching compatible with aluminum metallization  

Microsoft Academic Search

This paper reports on sacrificial oxide etching with very high selectivity to aluminum metallization using mixtures of 73% HF and IPA. Etch rate ratios up to 680 have been achieved even for (slow etching) thermal oxide. Thermal oxide etch rates up to 1.8 ?m\\/min. are reported. Thick polysilicon accelerometers with aluminum metallization and thermal sacrificial oxide have been made as

P. T. J. Gennissen; P. J. French

1997-01-01

399

Opportunities for functional oxides in yttrium oxide-titanium oxide-zirconium oxide system: Applications for novel thermal barrier coatings  

NASA Astrophysics Data System (ADS)

This dissertation is an investigation of materials and processed under consideration for next generation thermal structural oxides with potential applications as thermal barrier coatings; wherein, high temperature stability and mechanical properties affect durability. Two notable next generation materials systems under investigation are pyrochlore and co-doped zirconia oxides. The motivation for this work is based on current limitations of the currently used thermal barrier material of yttria stabilized zirconia (YSZ) deposited by the plasma spray processes. The rapid quenching associated with the plasma spray process, results in a metastable structure that is a non-transformable tetragonal structure in the yttria partially stabilized zirconia system rather than the equilibrium anticipated two phase mixture of cubic and monoclinic phases. It has been shown that this metastable structure offers enhanced toughness and thus durability during thermomechanical cycling from the operating temperatures in excess of 1000C to ambient. However, the metastable oxides are susceptible to partitioning at temperatures greater than 1200C, thus resulting in a transformation of the tetragonal phase oxides. Transformations of the tetragonal prime phase into the parent cubic and tetragonal prime phase result in coating degradation. Several of the emerging oxides are based on rare earth additions to zirconia. However, there is limited information of the high temperature stability of these oxide coatings and more notably these compositions exhibit limited toughness for durable performance. A potential ternary composition based on the YSZ system that offers the ability to tailor the phase structure is based YO1.5-TiO2 -ZrO2. The ternary of YO1.5-TiO2-ZrO 2 has the current TBC composition of seven molar percent yttria stabilized zirconia, pyrochlore phase oxide and zirconia doped with yttria and titania additions (Ti-YSZ). The Ti-YSZ phase field is of interest because at equilibrium it is a single tetragonal phase. Thus, compositions are of single phase tetragonal phase, theoretically, should not undergo high temperature partitioning. Single Tetragonal phase oxides of Ti-YSZ also offer the possibility of enhanced toughness and higher temperature stability akin to those observed in yttria partially stabilized zirconia. Many pyrochlore oxides are under review because they have shown to have lower thermal conductivity than YSZ oxides. This study focused on chemically synthesizing homogeneous starting material compositions in a metastable state (preferably amorphous), following its evolution according to the phase hierarchy under conditions of kinetic constraints. The current equilibrium diagram of YO1.5-TiO2-ZrO 2 is based on theoretical calculations. One of the contributions of this work is the redefined phase fields in YO1.5-TiO2-ZrO 2 based on our experimental results. Investigated compositions were based on tie lines of Y2-xTi2ZrxO7+x/2 and Y2Ti2-yZryO7 representing substitution of Zr4+ for Y3+ and Zr4+ for Ti4+ respectively. More notably, we observed extended metastable phases in pyrochlore and fluorite oxides at low temperature. The significance of this result is that it offers a larger compositional range for investing pyrochlore oxides with associated high temperature phase stability for TBC applications. In tetragonal oxides, our results showed that Ti-YSZ results have slower partitioning kinetics in comparison to YSZ at high temperature. This study also emphasized the deposition of advanced ceramic coatings by plasma spray for tetragonal and pyrochlore systems, compositionally complex functional oxides that may potentially have lower thermal conductivity values compared to current YSZ oxides. Next generation thermal barrier coatings require powders with high chemical purity, chemical homogeneity, controlled particle size/shape and pertinent phase state. Thermal spray offers an avenue to create novel materials and deposits directly from the precursor and compositionally controlled powder feedstock. This study contributed to investigating a

Francillon, Wesley

400

Theoretical model for the anodic oxidation of organics on metal oxide electrodes  

Microsoft Academic Search

A theoretical model describing the electrochemical oxidation of organics at oxide electrodes (MOx) forming the higher oxide (MOx+1) is described. In this model both organics oxidation and O2 evolution are mediated by the higher oxide (MOx+1) which is electrogenerated at the anode surface. The effect of concentration polarization in the electrolyte is also included in the theoretical model.

O. Simond; V. Schaller; Ch. Comninellis

1997-01-01

401

Water oxidation intermediates applied to catalysis: benzyl alcohol oxidation.  

PubMed

Four distinct intermediates, Ru(IV)?O(2+), Ru(IV)(OH)(3+), Ru(V)?O(3+), and Ru(V)(OO)(3+), formed by oxidation of the catalyst [Ru(Mebimpy)(4,4'-((HO)(2)OPCH(2))(2)bpy)(OH(2))](2+) [Mebimpy = 2,6-bis(1-methylbenzimidazol-2-yl) and 4,4'-((HO)(2)OPCH(2))(2)bpy = 4,4'-bismethylenephosphonato-2,2'-bipyridine] on nanoITO (1-PO(3)H(2)) have been identified and utilized for electrocatalytic benzyl alcohol oxidation. Significant catalytic rate enhancements are observed for Ru(V)(OO)(3+) (~3000) and Ru(IV)(OH)(3+) (~2000) compared to Ru(IV)?O(2+). The appearance of an intermediate for Ru(IV)?O(2+) as the oxidant supports an O-atom insertion mechanism, and H/D kinetic isotope effects support net hydride-transfer oxidations for Ru(IV)(OH)(3+) and Ru(V)(OO)(3+). These results illustrate the importance of multiple reactive intermediates under catalytic water oxidation conditions and possible control of electrocatalytic reactivity on modified electrode surfaces. PMID:22309164

Vannucci, Aaron K; Hull, Jonathan F; Chen, Zuofeng; Binstead, Robert A; Concepcion, Javier J; Meyer, Thomas J

2012-02-22

402

Oxidative coupling of methane over sodium promoted praseodymium oxide  

SciTech Connect

Unpromoted and alkali-promoted lanthanide oxides were evaluated in the oxidative coupling of methane to higher hydrocarbons. Methane conversion was carried out catalytically and in a redox mode by cycling methane and air independently over the lanthanide oxides. The sodium-promoted nonstoichiometric oxide, 4% Na on Pr{sub 6}O{sub 11}, was most active and selective, giving in the redox mode 21% methane conversion and 76% C{sub 2}{sup +} selectivity at 800 C and 1.4. WHSV (weight hourly space velocity, g CH{sub 4}/g cat. hr). At comparable conversion catalytic methane conversion had a C{sub 2}{sup +} selectivity of 64%. This selectivity deficit with respect to redox is attributed to an additional destructive route of the methyl radical, namely the reaction with molecular oxygen to yield a methylperoxy intermediate. Process variable studies support a mechanism whereby methane is activated at the metal oxide surface to form a methyl radical and in the gas phase C{sub 2}{sup +} hydrocarbon building occurs.

Gaffney, A.M.; Jones, C.A.; Leonard, J.J.; Sofranko, J.A. (ARCO Chemical Company, Newton Square, PA (USA))

1988-12-01

403

Oxidation of enrofloxacin with conductive-diamond electrochemical oxidation, ozonation and Fenton oxidation: a comparison.  

PubMed

The treatment of enrofloxacin synthetic wastewaters using conductive-diamond electrochemical oxidation (CDEO), ozonation and Fenton oxidation has been studied. Results show that the three technologies can reduce the organic content of enrofloxacin synthetic wastewaters but with different performances. CDEO was the most efficient technology in terms of mineralization but not on COD removal, which was more efficiently achieved by ozonation. This indicates that ozonation is efficient in the breakage of the complex molecules but not on the removal of final carboxylic acids. The high initial efficiency in terms of oxidant-use obtained by Fenton oxidation evidences that it is very efficient in the removal of the enrofloxacin, although it rapidly leads to the formation of refractory compounds to the treatment. This indicates the significance of other oxidation mechanisms (e.g. coagulation) that enhance the results obtained by the expected hydroxyl-mediated oxidation. Ammonium ions were the primary product species in CDEO and nitrate ions in ozonation, whereas Fenton effluents contained similar amounts of both nitrogen ionic species. PMID:19282017

Guinea, Elena; Brillas, Enric; Centellas, Francesc; Cańizares, Pablo; Rodrigo, Manuel A; Sįez, Cristina

2009-02-27

404

Structure, adhesion, and stability of metal/oxide and oxide/oxide interfaces  

SciTech Connect

Studies of several model metal/oxide and oxide/oxide interfaces were carried out by depositing ultra-thin metal thins on single crystal oxide substrates. The specific systems that were characterized include K/TiO{sub 2}, K{sub 2}O/TiO{sub 2}, Al/TiO{sub 2}, Al{sub 2}O{sub 3}/TiO{sub 2}, and K/NiO. The interface electronic structure and bonding interactions were determined with x-ray and uv photoelectron spectroscopies (XPS and UPS) and the structure and morphology was analyzed with low energy and high energy electron diffraction (LEED and RHEED) and atomic force microscopy (AFM). The two metal overlayers studies, K and Al, were found to strongly interact with the single crystal oxide substrates. Given adequate thermal energy, the metals became oxidized and substoichiometric TiO{sub 2} and NiO compositions were created near the interface. Defects were found to have a major influence on interface structure. The construction of the thin film deposition/RHEED analysis chamber was completed during the past year, and a versatile sample transfer and heating system was implemented. Three graduate students participated in the project, the results were presented at three national meetings, and one manuscript was submitted for publication.

Lad, R.J.

1992-01-01

405

Oxidation of coal: a mechanistic puzzle  

Microsoft Academic Search

The mechanism of coal oxidation was investigated by two-phase oxidation of hvb and lvb coals. The oxidants used were commercial bleach, tetrabutylammonium fluoroborate and tetrabutylammonium permanganate. After extraction, the compounds were characterized by gas chromatography\\/mass spectroscopy. Coal-oxidation is much more complicated than would be expected from oxidations of standard organic compounds. It is reasonable to assume that aliphatic structures, particularly

Chakrabartty

1981-01-01

406

Method for plating with metal oxides  

DOEpatents

A method of plating hydrous metal oxides on at least one substrate, which method is indifferent to the electrochemical properties of the substrate, and comprises reacting metallic ions in aqueous solution with an appropriate oxidizing agent such as sodium hypochlorite or calcium sulfite with oxygen under suitable conditions of pH and concentration such that oxidation and precipitation of metal oxide are sufficiently slow to allow satisfactory plating of metal oxide on the substrate.

Silver, Gary L. (Centerville, OH); Martin, Frank S. (Farmersville, OH)

1994-08-23

407

Oxidation behavior of titanium-aluminium nitrides  

Microsoft Academic Search

Oxidation behavior of titanium-aluminium nitrides of various compositions has been explored to understand the oxidation protection mechanisms and the role of structure and composition in the oxidation behavior. Thin films of (Ti1-x,Alx)N have been sputter deposited on silicon substrates and the nature of oxides resulting from air oxidation at various temperatures has been evaluated using Auger electron spectroscopy. In most

A. Joshi; H. S. Hu

1995-01-01

408

Microalgal-facilitated bacterial oxidation of manganese  

Microsoft Academic Search

In the presence of unicellular microalgae, bacterial manganese oxidation was increased by up to ten times the rate produced by bacterial oxidation alone. Azide-poisoned controls demonstrated that the manganese-oxidizing bacteria were active in the algal-bacterial oxidation of manganese. Scanning electron microscopy showed that oxide formation occurred in a number of structurally different deposits on the surface of the alga. Studies

R M Stuetz; A C Greene; J C Madgwick

1996-01-01

409

Process for fabrication of metal oxide films  

DOEpatents

This invention is comprised of a method of fabricating metal oxide films from a plurality of reactants by inducing a reaction by plasma deposition among the reactants. The plasma reaction is effective for consolidating the reactants and producing thin films of metal oxides, e.g. electro-optically active transition metal oxides, at a high deposition rate. The presence of hydrogen during the plasma reaction enhances the deposition rate of the metal oxide. Various types of metal oxide films can be produced.

Tracy, C.E.; Benson, D.; Svensson, S.

1990-07-17

410

The anaerobic oxidation of ammonium.  

PubMed

From recent research it has become clear that at least two different possibilities for anaerobic ammonium oxidation exist in nature. 'Aerobic' ammonium oxidizers like Nitrosomonas eutropha were observed to reduce nitrite or nitrogen dioxide with hydroxylamine or ammonium as electron donor under anoxic conditions. The maximum rate for anaerobic ammonium oxidation was about 2 nmol NH4+ min-1 (mg protein)-1 using nitrogen dioxide as electron acceptor. This reaction, which may involve NO as an intermediate, is thought to generate energy sufficient for survival under anoxic conditions, but not for growth. A novel obligately anaerobic ammonium oxidation (Anammox) process was recently discovered in a denitrifying pilot plant reactor. From this system, a highly enriched microbial community with one dominating peculiar autotrophic organism was obtained. With nitrite as electron acceptor a maximum specific oxidation rate of 55 nmol NH4+ min-1 (mg protein)-1 was determined. Although this reaction is 25-fold faster than in Nitrosomonas, it allowed growth at a rate of only 0.003 h-1 (doubling time 11 days). 15N labeling studies showed that hydroxylamine and hydrazine were important intermediates in this new process. A novel type of hydroxylamine oxidoreductase containing an unusual P468 cytochrome has been purified from the Anammox culture. Microsensor studies have shown that at the oxic/anoxic interface of many ecosystems nitrite and ammonia occur in the absence of oxygen. In addition, the number of reports on unaccounted high nitrogen losses in wastewater treatment is gradually increasing, indicating that anaerobic ammonium oxidation may be more widespread than previously assumed. The recently developed nitrification systems in which oxidation of nitrite to nitrate is prevented form an ideal partner for the Anammox process. The combination of these partial nitrification and Anammox processes remains a challenge for future application in the removal of ammonium from wastewater with high ammonium concentrations. PMID:9990725

Jetten, M S; Strous, M; van de Pas-Schoonen, K T; Schalk, J; van Dongen, U G; van de Graaf, A A; Logemann, S; Muyzer, G; van Loosdrecht, M C; Kuenen, J G

1998-12-01

411

Electrorheological Properties of Suspensions of Polypyrrole Ribbon Particles in Silicone Oil  

Microsoft Academic Search

A new polypyrrole (PPy) ribbon particles structure has been synthesized by solution chemistry method (oxidative polymerization) in the presence of surfactant cetyltrimethylammonium bromide (CTAB) with oxidizing agent ammonium persulfate (APS). The resulted polymer was treated with ammonium hydroxide (NH4OH) several times to obtain different sample conductivity. PPy morphology was characterized by SEM. The suspensions were prepared by dispersing PPy with

Shawqi Almajdalawi; Vladimir Pavlinek; Qilin Cheng; Petr Saha; Miroslav Mrlik; Martin Stenicka

2011-01-01

412

Effects of Surface Modifications on the Peel Strength of Copper Based Polymer\\/Metal Interfaces with Characteristic Morphologies  

Microsoft Academic Search

This paper summarizes a study on the effect of changes in surface chemistry on the peel strength of copper\\/polymer interfaces. Two different surface topographics were created and evaluated, one produced by cleaning and etching in sodium persulfate, the other by etching then mechanically roughening using 180 grit sandpaper. Both surfaces were then oxidized in an alkaline\\/oxidizing treatment to form cupric

B. J. Love; P. F. Packman

1993-01-01

413

Anomalous oxidation states in oxide multilayers for fuel cell applications  

SciTech Connect

Significant interest has been directed towards interface enhanced ionic conductivity. Advanced analytical techniques including electron microscopy (TEM/STEM), electron energy loss spectroscopy (EELS), and secondary ion mass spectrometry (SIMS) have been used to characterize CeO2/Ce0.85Sm0.15O2 multilayer thin films grown by pulsed laser deposition. High quality growth is observed, but ionic conductivity measured by impedance spectroscopy and 18O tracer experiments is consistent with bulk materials. EELS analysis reveals the unusual situation of layers containing only Ce(IV) adjacent to layers containing both Ce(III) and Ce(IV). Post oxygen annealing induced oxygen diffusion and mixed oxidation states in both layers, but only in the vicinity of low angle grain boundaries perpendicular to the layers. The implications of this remarkable metastability of Ce oxidation states on the design of novel electrolytes for solid oxide fuel cells is discussed.

Perkins, James [Imperial College, London; Fearn, Sarah [Imperial College, London; Cook, S. N. [Imperial College, London; Srinivasan, R. [Imperial College, London; Rouleau, Christopher M [ORNL; Christen, Hans M [ORNL; West, G. D. [Imperial College, London; Morris, R. J. H. [Imperial College, London; Fraser, H. L. [Imperial College, London; Skinner, Stephen [Imperial College, London; Kilner, John [Imperial College, London; McComb, David [Imperial College, London

2010-01-01

414

Methanol oxidation over nonprecious transition metal oxide catalysts  

SciTech Connect

This paper reports methanol oxidation over nonprecious transition metal oxide catalysts studied in a gradient less external recycle reactor. The catalysts (oxides of Cr, Mn, Fe, Co, Ni, Cu), which were prepared by using the incipient wetness technique, were supported on 1/8 in.{gamma}-Al{sub 2}O{sub 3} tablets. The catalysts were characterized by using BET surface area measurement, X-ray diffraction, laser Raman spectroscopy, scanning electron microscopy, and energy dispersive X-ray analysis techniques. All the catalysts exhibited similar activities for methanol conversion, but the Cu catalyst was found to be considerably more selective to CO{sub 2}. The order of the reaction was 1.2 with respect to methanol concentration and appeared to range between 0.5 and 0 with respect to oxygen concentration.

Ozkan, U.S.; Kueller, R.F.; Moctezuma, E. (Ohio State Univ., Columbus, OH (USA). Dept. of Chemical Engineering)

1990-07-01

415

Genotoxicity assessment of ?-caryophyllene oxide.  

PubMed

?-caryophyllene oxide is a biciclic sesquiterpene, occurring naturally in essential oils from various medicinal and edible plants and used as a flavouring agent. Due to its potential hazardous chemical structure, the European Food Safety Authority reported to be pending a safety assessment for this compound. Here, this flavouring agent was tested for its mutagenic effect in the Ames test and micronucleus assay. Furthermore, considering that the penetration of a substance through phospholipid bilayers is determinant for its activity, the ability of ?-caryophyllene oxide to be absorbed into cells was evaluated by differential scanning calorimetry (DSC) using multilamellar vesicles of dimyristoylphosphatidylcholine as a biomembrane model. ?-caryophyllene oxide was found to be devoid of mutagenic effect, both at gene level (frameshift or base-substitution mutations), and on chromosome (clastogenicity and aneuploidogenicity). Results of DSC analysis highlighted that the substance was strongly absorbed through the membrane bilayer. Present results show that ?-caryophyllene oxide, although absorbed through cell membranes and in spite of its potentially reactive chemical structure, is devoid of genotoxic effects, inducing neither point mutations nor chromosomal damages. These negative genotoxic findings will be critical to the safety assessment of ?-caryophyllene oxide as used as a flavouring/fragrance ingredient. PMID:23659888

Di Sotto, Antonella; Maffei, Francesca; Hrelia, Patrizia; Castelli, Francesco; Sarpietro, Maria Grazia; Mazzanti, Gabriela

2013-05-07

416

Oxidative stress and liver disease.  

PubMed

In humans, oxidative stress and antioxidant defenses are the sum of a complicated network of enzymatic and non-enzymatic processes. Depending on the stage and severity of diseases, a patient's antioxidant armamentarium may increase as an appropriate response to an oxidant challenge, whereas others may decrease as an indication of unbalanced consumption. In some cases, the formation of reactive oxygen species is a requisite and healthy event. In fact, free radicals can affect intracellular signal transduction and gene regulation, resulting in cytokine production essential to the inflammatory process. In many other cases, especially liver diseases, excessive oxidative stress undoubtedly contributes to the progression and pathological findings of disease and serves as a prognostic indicator. Reactive oxygen species are highly reactive molecules that are naturally generated in small amounts through metabolism and could damage cellular molecules such as lipids, proteins or DNA. Oxidative stress plays a major role in many liver diseases. In this review, we summarize the biological character of free radicals and some antioxidants, and the related methods of analysis. Then, we discusses the association of oxidative stress to many types of liver diseases. PMID:22489668

Zhu, Runzhi; Wang, Yajing; Zhang, Liangqing; Guo, Qinglong

2012-04-11

417

Oxidative stress and diabetes mellitus.  

PubMed

Increasing evidences have suggested that oxidative stress plays a major role in the pathogenesis of diabetes mellitus (DM). Oxidative stress also appears to be the pathogenic factor in underlying diabetic complications. Reactive oxygen species (ROS) are generated by environmental factors, such as ionizing radiation and chemical carcinogens, and also by endogenous processes, including energy metabolism in mitochondria. ROS produced either endogenously or exogenously can attack lipids, proteins and nucleic acids simultaneously in living cells. There are many potential mechanisms whereby excess glucose metabolites traveling along these pathways might promote the development of DM complication and cause pancreatic ? cell damage. However, all these pathways have in common the formation of ROS, that, in excess and over time, causes chronic oxidative stress, which in turn causes defective insulin gene expression and insulin secretion as well as increased apoptosis. Various methods for determining biomarkers of cellular oxidative stress have been developed, and some have been proposed for sensitive assessment of antioxidant defense and oxidative damage in diabetes and its complications. However, their clinical utility is limited by less than optimal standardization techniques and the lack of sufficient large-sized, multi-marker prospective trials. PMID:21810068

Yang, Hui; Jin, Xun; Kei Lam, Christopher Wai; Yan, Sheng-Kai

2011-08-03

418

Oxide fiber targets at ISOLDE  

NASA Astrophysics Data System (ADS)

Many elements are rapidly released from oxide matrices. Some oxide powder targets show a fast sintering, thus losing their favorable release characteristics. Loosely packed oxide fiber targets are less critical since they may maintain their open structure even when starting to fuse together at some contact points. The experience with various oxide fiber targets (titania, zirconia, ceria and thoria) used in the last years at ISOLDE is reviewed. For short-lived isotopes of Cu, Ga and Xe the zirconia and ceria targets respectively provided significantly higher yields than any other target (metal foils, oxide powders, etc.) tested before. Titania fibers, which were not commercially available, were produced in a relic process by impregnation of a rayon felt in a titanium chloride solution and subsequent calcination by heating the dried felt in air. Thoria fibers were obtained either by the same process or by burning commercial gas lantern mantle cloth. In the future a beryllia fiber target could be used to produce very intense 6He beams (order of 1013 ions per second) via the 9Be(n,?) reaction using spallation neutrons.

ISOLDE Collaboration; Köster, U.; Bergmann, U. C.; Carminati, D.; Catherall, R.; Cederkäll, J.; Correia, J. G.; Crepieux, B.; Dietrich, M.; Elder, K.; Fedoseyev, V. N.; Fraile, L.; Franchoo, S.; Fynbo, H.; Georg, U.; Giles, T.; Joinet, A.; Jonsson, O. C.; Kirchner, R.; Lau, Ch.; Lettry, J.; Maier, H. J.; Mishin, V. I.; Oinonen, M.; Peräjärvi, K.; Ravn, H. L.; Rinaldi, T.; Santana-Leitner, M.; Wahl, U.; Weissman, L.

2003-05-01

419

Improved synthesis of graphene oxide.  

PubMed

An improved method for the preparation of graphene oxide (GO) is described. Currently, Hummers' method (KMnO(4), NaNO(3), H(2)SO(4)) is the most common method used for preparing graphene oxide. We have found that excluding the NaNO(3), increasing the amount of KMnO(4), and performing the reaction in a 9:1 mixture of H(2)SO(4)/H(3)PO(4) improves the efficiency of the oxidation process. This improved method provides a greater amount of hydrophilic oxidized graphene material as compared to Hummers' method or Hummers' method with additional KMnO(4). Moreover, even though the GO produced by our method is more oxidized than that prepared by Hummers' method, when both are reduced in the same chamber with hydrazine, chemically converted graphene (CCG) produced from this new method is equivalent in its electrical conductivity. In contrast to Hummers' method, the new method does not generate toxic gas and the temperature is easily controlled. This improved synthesis of GO may be important for large-scale production of GO as well as the construction of devices composed of the subsequent CCG. PMID:20731455

Marcano, Daniela C; Kosynkin, Dmitry V; Berlin, Jacob M; Sinitskii, Alexander; Sun, Zhengzong; Slesarev, Alexander; Alemany, Lawrence B; Lu, Wei; Tour, James M

2010-08-24

420

Cadmium stress: an oxidative challenge.  

PubMed

At the cellular level, cadmium (Cd) induces both damaging and repair processes in which the cellular redox status plays a crucial role. Being not redox-active, Cd is unable to generate reactive oxygen species (ROS) directly, but Cd-induced oxidative stress is a common phenomenon observed in multiple studies. The current review gives an overview on Cd-induced ROS production and anti-oxidative defense in organisms under different Cd regimes. Moreover, the Cd-induced oxidative challenge is discussed with a focus on damage and signaling as downstream responses. Gathering these data, it was clear that oxidative stress related responses are affected during Cd stress, but the apparent discrepancies observed in between the different studies points towards the necessity to increase our knowledge on the spatial and temporal ROS signature under Cd stress. This information is essential in order to reveal the exact role of Cd-induced oxidative stress in the modulation of downstream responses under a diverse array of conditions. PMID:20361350

Cuypers, Ann; Plusquin, Michelle; Remans, Tony; Jozefczak, Marijke; Keunen, Els; Gielen, Heidi; Opdenakker, Kelly; Nair, Ambily Ravindran; Munters, Elke; Artois, Tom J; Nawrot, Tim; Vangronsveld, Jaco; Smeets, Karen

2010-04-02

421

Solid oxide electrochemical reactor science.  

SciTech Connect

Solid-oxide electrochemical cells are an exciting new technology. Development of solid-oxide cells (SOCs) has advanced considerable in recent years and continues to progress rapidly. This thesis studies several aspects of SOCs and contributes useful information to their continued development. This LDRD involved a collaboration between Sandia and the Colorado School of Mines (CSM) ins solid-oxide electrochemical reactors targeted at solid oxide electrolyzer cells (SOEC), which are the reverse of solid-oxide fuel cells (SOFC). SOECs complement Sandia's efforts in thermochemical production of alternative fuels. An SOEC technology would co-electrolyze carbon dioxide (CO{sub 2}) with steam at temperatures around 800 C to form synthesis gas (H{sub 2} and CO), which forms the building blocks for a petrochemical substitutes that can be used to power vehicles or in distributed energy platforms. The effort described here concentrates on research concerning catalytic chemistry, charge-transfer chemistry, and optimal cell-architecture. technical scope included computational modeling, materials development, and experimental evaluation. The project engaged the Colorado Fuel Cell Center at CSM through the support of a graduate student (Connor Moyer) at CSM and his advisors (Profs. Robert Kee and Neal Sullivan) in collaboration with Sandia.

Sullivan, Neal P. (Colorado School of Mines, Golden, CO); Stechel, Ellen Beth; Moyer, Connor J. (Colorado School of Mines, Golden, CO); Ambrosini, Andrea; Key, Robert J. (Colorado School of Mines, Golden, CO)

2010-09-01

422

Oxidation and Assimilation of Atmospheric Methane by Soil Methane Oxidizers  

PubMed Central

The metabolism of atmospheric methane in a forest soil was studied by radiotracer techniques. Maximum (sup14)CH(inf4) oxidation (163.5 pmol of C cm(sup-3) h(sup-1)) and (sup14)C assimilation (50.3 pmol of C cm(sup-3) h(sup-1)) occurred at the A(inf2) horizon located 15 to 18 cm below the soil surface. At this depth, 31 to 43% of the atmospheric methane oxidized was assimilated into microbial biomass; the remaining methane was recovered as (sup14)CO(inf2). Methane-derived carbon was incorporated into all major cell macromolecules by the soil microorganisms (50% as proteins, 19% as nucleic acids and polysaccharides, and 5% as lipids). The percentage of methane assimilated (carbon conversion efficiency) remained constant at temperatures between 5 and 20(deg)C, followed by a decrease at 30(deg)C. The carbon conversion efficiency did not increase at methane concentrations between 1.7 and 1,000 ppm. In contrast, the overall methane oxidation activity increased at elevated methane concentrations, with an apparent K(infm) of 21 ppm (31 nM CH(inf4)) and a V(infmax) of 188 pmol of CH(inf4) cm(sup-3) h(sup-1). Methane oxidizers from soil depths with maximum methanotrophic activity respired approximately 1 to 3% of the assimilated methane-derived carbon per day. This apparent endogenous respiration did not change significantly in the absence of methane. Similarly, the potential for oxidation of atmospheric methane was relatively insensitive to methane starvation. Soil samples from depths above and below the zone with maximum atmospheric methane oxidation activity showed a dramatic increase in the turnover of the methane assimilated (>20 times increase). Physical disturbance such as sieving or mixing of soil samples decreased methane oxidation and assimilation by 50 to 58% but did not alter the carbon conversion efficiency. Ammonia addition (0.1 or 1.0 (mu)mol g [fresh weight](sup-1)) decreased both methane oxidation and carbon conversion efficiency. This resulted in a dramatic decrease in methane assimilation (85 to 99%). In addition, ammonia-treated soil showed up to 10 times greater turnover of the assimilated methane-derived carbon (relative to untreated soil). The results suggest a potential for microbial growth on atmospheric methane. However, growth was regulated strongly by soil parameters other than the methane concentration. The pattern observed for metabolism of atmospheric methane in soils was not consistent with the physiology of known methanotrophic bacteria.

Roslev, P.; Iversen, N.; Henriksen, K.

1997-01-01

423

Vanadium Oxide Based Nanostructured Materials: Novel Oxidative Dehydrogenation Catalysts  

Microsoft Academic Search

Novel vanadium oxide based catalyst derived from the open-framework solid, [Co3V18O42(H2O)12(XO4)]·24 H2O (X = V, S) (1) catalyses oxidative dehydrogenation of propane to propylene. Catalyst activity was evaluated in the temperature range 250–400 °C\\u000a with varying gas hourly space velocity (GHSV). At 350 °C and GHSV of 9786 h?1 and at 1.3% propane conversion the selectivity to propylene was 36.8%. The major products obtained were propylene

M. Ishaque Khan; Sangita Deb; Christopher L. Marshall

2009-01-01

424

Nitric-oxide myoglobin as an inhibitor of lipid oxidation  

Microsoft Academic Search

The effect of nitric-oxide myoglobin (MbNO) on lipid oxidation was studied in linoleate and ?-carotene-linoleate aqueous model\\u000a systems and compared with that of metmyoglobin (MMb) and oxymyoglobin (MbO2) in short- and long-term reactions. While MMb and MbO2 had a clear prooxidative effect, MbNO, under the same conditions, acted as an antioxidant. The specific antioxidative activity\\u000a of MbNO was maintained even

Joseph Kanner; Itamar Ben-Gera; Shura Berman

1980-01-01

425

Kinetics of Starch Oxidation in the System Nitrogen(IV) Oxide-Tetrachloromethane  

Microsoft Academic Search

Kinetics of potato starch oxidation by dinitrogen tetroxide in CCl4 was studied as influenced by the oxidant concentration, temperature, and starch to N2O4 ratio. The starch oxidation products were analyzed by IR spectroscopy.

S. M. Butrim; T. D. Bil'dyukevich; T. L. Yurkshtovich

2001-01-01

426

OXIDATION OF NITROPYRIN TO 6-CHOLORPICOLINIC ACID BY THE AMMONIA-OXIDIZING BACTERIUM NOSTROSOMAS EUROPAEA  

EPA Science Inventory

Suspensions of Nitrosomonas europaea catalyzed the oxidation of the commercial nitrification inhibitor nitrapyrin [2-chloro-6-(trichloromethyl)-pyridine]. apid oxidation of nitrapyrin (at a concentration of 10 uM) required the concomitant oxidation of ammonia, hydroxylamine, or h...

427

Vacancy coalescence during oxidation of iron nanoparticles  

SciTech Connect

In the present work, we analyze the geometry and composition of the nanostructures obtained from the oxidation of iron nanoparticles. The initial oxidation of iron takes place by outward diffusion of cations through the growing oxide shell. This net material flow is balanced by an opposite flow of vacancies, which coalesce at the metal/oxide interface. Thus, the partial oxidation of colloidal iron nanoparticles leads to the formation of core-void-shell nanostructures. Furthermore, the complete oxidation of iron nanoparticles in the 3-8 nm size range leads to the formation of hollow iron oxide nanoparticles. We analyze the size and temperature range in which vacancy coalescence during oxidation of amine-stabilized iron nanoparticles takes place. Maghemite is the crystallographic structure obtained from the complete oxidation of iron nanoparticles under our synthetic conditions.

Cabot, Andreu; Puntes, Victor F.; Shevchenko, Elena; Yin, Yadong; Balcells, Lluis; Markus, Matthew A.; Hughes, Steven M.; Alivisatos, A. Paul

2007-06-14

428

Method for hot pressing beryllium oxide articles  

DOEpatents

The hot pressing of beryllium oxide powder into high density compacts with little or no density gradients is achieved by employing a homogeneous blend of beryllium oxide powder with a lithium oxide sintering agent. The lithium oxide sintering agent is uniformly dispersed throughout the beryllium oxide powder by mixing lithium hydroxide in an aqueous solution with beryllium oxide powder. The lithium hydroxide is converted in situ to lithium carbonate by contacting or flooding the beryllium oxide-lithium hydroxide blend with a stream of carbon dioxide. The lithium carbonate is converted to lithium oxide while remaining fixed to the beryllium oxide particles during the hot pressing step to assure uniform density throughout the compact.

Ballard, Ambrose H. (Oak Ridge, TN); Godfrey, Jr., Thomas G. (Oak Ridge, TN); Mowery, Erb H. (Clinton, TN)

1988-01-01

429

Thin oxides with in situ native oxide removal [n-MOSFETs  

Microsoft Academic Search

We have studied the inversion layer mobility of n-MOSFET's with thin-gate oxide of 20 to 70 Å. Direct relationship of electron mobility to oxide\\/channel interface roughness was obtained from measured mobility of MOSFET's and high-resolution TEM. By using a low-pressure oxidation process with native oxide removed in situ prior to oxidation, atomically smooth interface of oxide\\/channel was observed by high-resolution

Albert Chin; W. J. Chen; T. Chang; R. H. Kao; B. C. Lin; C. Tsai; J. C.-M. Huang

1997-01-01

430

Electrochemical oxidation of chemical weapons  

SciTech Connect

Catalyzed electrochemical oxidation (CEO), a low-temperature electrochemical oxidation technique, is being examined for its potential use in destroying chemical warfare agents. The CEO process oxidizes organic compounds to form carbon dioxide and water. A bench-scale CEO system was used in three separate tests sponsored by the US Department of Energy`s (DOE) Office of Intelligence and National Security through the Advanced Concepts Program. The tests examined the effectiveness of CEO in destroying sarin (GB), a chemical nerve agent. The tests used 0.5 mL, 0.95 mL, and 1.0 mL of GB, corresponding to 544 mg, 816 mg, and 1,090 mg, respectively, of GB. Analysis of the off gas showed that, under continuous processing of the GB agent, destruction efficiencies of better than six 9s (99.9999% destroyed) could be achieved.

Surma, J.E.

1994-05-01

431

Graphite Oxidation Thermodynamics/Reactions  

SciTech Connect

The vulnerability of graphite-matrix spent nuclear fuel to oxidation by the ambient atmosphere if the fuel canister is breached was evaluated. Thermochemical and kinetic data over the anticipated range of storage temperatures (200 to 400 C) were used to calculate the times required for a total carbon mass loss of 1 mgcm-2 from a fuel specimen. At 200 C, the time required to produce even this small loss is large, 900,000 yr. However, at 400 C the time required is only 1.9 yr. The rate of oxidation at 200 C is negligible, and the rate even at 400 C is so small as to be of no practical consequence. Therefore, oxidation of the spent nuclear fuel upon a loss of canister integrity is not anticipated to be a concern based upon the results of this study.

Propp, W.A.

1998-09-01

432

PREPARATION OF REFRACTORY OXIDE CRYSTALS  

DOEpatents

A method is given for preparing uranium dioxide, thorium oxide, and beryllium oxide in the form of enlarged individual crystals. The surface of a fused alkali metal halide melt containing dissolved uranium, thorium, or beryllium values is contacted with a water-vapor-bearing inert gas stream at a rate of 5 to 10 cubic centimeters per minute per square centimeter of melt surface area. Growth of individual crystals is obtained by prolonged contact. Beryllium oxide-coated uranium dioxide crystals are prepared by disposing uranium dioxide crystals 5 to 20 microns in diameter in a beryllium-containing melt and contacting the melt with a water-vapor-bearing inert gas stream in the same manner. (AEC)

Grimes, W.R.; Shaffer, J.H.; Watson, G.M.

1962-11-13

433

Molybdenum oxidation by Thiobacillus ferrooxidans  

SciTech Connect

Thiobacillus ferrooxidans AP19-3 oxidized molybednum blue (Mo[sup 5+]) enzymatically. Molybednum oxidase in the plasma membrane of this bacterium was purified ca. 77-fold compared with molybdenum oxidase in cell extract. A purified molybdenum oxidase showed characteristic absorption maxima due to reduced-type cytochrome oxidase at 438 and 595 nm but did not show absorption peaks specific for c-type cytochrome. The optimum pH of molybdenum oxidase was 5.5. The activity of molybdenum oxidase was completely inhibited by sodium cyanide or carbon monoxide, and an oxidized type of cytochrome oxidase in a purified molybdenum oxidase was reduced by molybdenum blue, indicating that cytochrome oxidase in the enzyme plays a crucial role in molybdenum blue oxidation.

Sugio, Tsuyoshi; Hirayama, Kouichi; Tano, Tatsuo; Inagaki, Kenji; Tanaka, Hidehiko (Okayama Univ., Naka (Japan))

1992-05-01

434

Anodic Oxidation of Zinc Phosphide  

NASA Astrophysics Data System (ADS)

Initial stages of a native oxidation on Zn3P2 by anodization have been investigated for the first time using 3% tartaric acid/propylene glycol electrolyte. A constant-current anodization is found to be superior to a constant-voltage anodization because of the rapid growth of the initial stage in the constant-voltage mode in view of controlling thin oxide layers. The surface composition of anodized Zn3P2 was examined by AES and XPS. The oxide layer was identified as a mixture of ZnO, P2O5, and P2O3: the increased [P2O5+P2O3]/[ZnO] ratio of ˜ 1.3 was obtained at acidic and basic pH values, whereas the composition ratio was ˜ 0.2 near a neutral pH value as a result of selective dissolution of either ZnO or POx.

Suda, Toshikazu; Murata, Yoshitada; Kurita, Shoichi

1986-02-01

435

Controlling nitrogen oxides. Research summary  

SciTech Connect

Recent research indicates that nitrogen oxides (NOx) could be one of the most troublesome air pollutants of the 1980's. More than 20 million metric tons of NOx are annually polluting our air as a result of the widespread combustion of fossil fuels in power plants, industrial boilers, and automobiles and trucks. Present levels of NOx emissions already pose a significant threat to our health and environment. Nitrogen oxides are directly harmful to human health, and are precursors of photochemical oxidants such as ozone, the major component of urban smog. They can also be converted into nitric acid, one of the two principal components of acid precipitation. The EPA is actively working with other Federal agencies and the academic, industrial, and private research communities to develop viable combustion technologies which will strictly limit NOx emissions. The authors have prepared this Research Summary to inform the public of the status of their efforts to make improved control technologies available as soon as possible.

Hastings, A.; Schaefer, M.

1980-02-01

436

[Oxidative stress and Alzheimer's disease].  

PubMed

Alzheimer's disease (AD) has become one of the most important and most interesting focuses in the field of medical and scientific research. Up to now, the pathogenesis of AD has not been completely clarified. However, the high-density of amyloid ?-protein (A?) in senile plaques of AD brain and the neurotoxicity of A? have been indisputable facts. The mechanisms underlying A? neurotoxicity are very complicated, involving calcium overload, inflammation, ion channel dysfunction, oxidative stress and so on. Among all of those, the mechanism of oxidative stress in A? neurotoxicity and the experimental progress of antioxidants in AD treatment have been widely reported in recent years. This review mainly discussed current research progresses on the oxidative stress of A?, so as to provide readers with some clues to the antioxidant therapy of AD. PMID:22348966

Liu, Xiao-Jie; Yang, Wei; Qi, Jin-Shun

2012-02-25

437

Pyrite oxidation in moist air  

NASA Astrophysics Data System (ADS)

The rate of pyrite oxidation in moist air was determined by measuring, over time, the pressure difference between a sealed chamber containing pyrite plus oxygen and a control. The experiments carried out at 25°C, 96.7% fixed relative humidity, and oxygen partial pressures of 0.21, 0.61, and 1.00 atm showed that the rate of oxygen consumption is a function of oxygen partial pressure and time. The rates of oxygen consumption ( r, mol/m 2sec) fit the expression dn/dt=10 -6.6P 0.5t -0.5 where P is the partial pressure of oxygen (atm) and t is time (sec). It appears that the rate slows with time because a thin layer of ferrous sulfate + sulfuric acid solution grows on the pyrite and retards oxygen transport to the pyrite surface. At very short reaction times, the rate of pyrite oxidation in air is slightly faster than the aqueous oxidation rate at the same oxygen partial pressure and temperature. At greater extents of reaction, the rate slows significantly and approaches the rates reported by humidity cell studies. This slower rate of oxidation in air appears to be more appropriate than the aqueous oxidation rate for modeling pyrite oxidation in unsaturated waste piles. At relative humidity less than 95%, a solid ferrous sulfate phase (melanterite or szolmonokite) becomes saturated and will precipitate from the ferrous sulfate + sulfuric acid solution in cracks and on the pyrite surface. These solids have the potential to wedge apart the sample leading to physical disaggregation of the pyrite as is often seen in museum samples.

Jerz, Jeanette K.; Rimstidt, J. Donald

2004-02-01

438

?-Oxidation of ?-Chlorinated Fatty Acids  

PubMed Central

Myeloperoxidase-derived HOCl targets tissue- and lipoprotein-associated plasmalogens to generate ?-chlorinated fatty aldehydes, including 2-chlorohexadecanal. Under physiological conditions, 2-chlorohexadecanal is oxidized to 2-chlorohexadecanoic acid (2-ClHA). This study demonstrates the catabolism of 2-ClHA by ?-oxidation and subsequent ?-oxidation from the ?-end. Mass spectrometric analyses revealed that 2-ClHA is ?-oxidized in the presence of liver microsomes with initial ?-hydroxylation of 2-ClHA. Subsequent oxidation steps were examined in a human hepatocellular cell line (HepG2). Three different ?-chlorinated dicarboxylic acids, 2-chlorohexadecane-(1,16)-dioic acid, 2-chlorotetradecane-(1,14)-dioic acid, and 2-chloroadipic acid (2-ClAdA), were identified. Levels of 2-chlorohexadecane-(1,16)-dioic acid, 2-chlorotetradecane-(1,14)-dioic acid, and 2-ClAdA produced by HepG2 cells were dependent on the concentration of 2-ClHA and the incubation time. Synthetic stable isotope-labeled 2-ClHA was used to demonstrate a precursor-product relationship between 2-ClHA and the ?-chlorinated dicarboxylic acids. We also report the identification of endogenous 2-ClAdA in human and rat urine and elevations in stable isotope-labeled urinary 2-ClAdA in rats subjected to intraperitoneal administration of stable isotope-labeled 2-ClHA. Furthermore, urinary 2-ClAdA and plasma 2-ClHA levels are increased in LPS-treated rats. Taken together, these data show that 2-ClHA is ?-oxidized to generate ?-chlorinated dicarboxylic acids, which include ?-chloroadipic acid that is excreted in the urine.

Brahmbhatt, Viral V.; Albert, Carolyn J.; Anbukumar, Dhanalakshmi S.; Cunningham, Bryce A.; Neumann, William L.; Ford, David A.

2010-01-01

439

Copper, silver, gold and zinc, cadmium, mercury oxides and hydroxides  

SciTech Connect

This book provides a compilation of solubility data published up to 1984, including evaluations of the data. Data are presented on the following: copper (I) oxide; copper (II) oxide and hydroxide; silver (I) oxide; silver (II) oxide; gold (III) hydroxide; zinc oxide and hydroxide; cadmium oxide and hydroxide; and mercury (II) oxide.

Dirkse, T.P.

1986-01-01

440

Photoinduced oxidation of carbon nanotubes  

NASA Astrophysics Data System (ADS)

Photoinduced phenomena are of general interest for new materials. Recently, photoinduced molecular desorption of oxygen has been reported in carbon nanotubes. Here we present, using thermopower measurements, that carbon nanotubes when exposed simultaneously to UV light and oxygen exhibit photoinduced oxidation of the nanotubes. At least two plausible mechanisms for the experimentally observed photoinduced oxidation are proposed: (i) a lower energy barrier for the adsorption of photo-generated singlet oxygen, or (ii) due to the presence of defects in carbon nanotubes that may facilitate the formation of locally electron-deficient and electron-rich regions on the nanotubes which facilitate the adsorption of oxygen molecules on the nanotubes.

Savage, T.; Bhattacharya, S.; Sadanadan, B.; Gaillard, J.; Tritt, T. M.; Sun, Y.-P.; Wu, Y.; Nayak, S.; Car, R.; Marzari, N.; Ajayan, P. M.; Rao, A. M.

2003-09-01

441

Superconducting interfaces between insulating oxides.  

PubMed

At interfaces between complex oxides, electronic systems with unusual electronic properties can be generated. We report on superconductivity in the electron gas formed at the interface between two insulating dielectric perovskite oxides, LaAlO3 and SrTiO3. The behavior of the electron gas is that of a two-dimensional superconductor, confined to a thin sheet at the interface. The superconducting transition temperature of congruent with 200 millikelvin provides a strict upper limit to the thickness of the superconducting layer of congruent with 10 nanometers. PMID:17673621

Reyren, N; Thiel, S; Caviglia, A D; Kourkoutis, L Fitting; Hammerl, G; Richter, C; Schneider, C W; Kopp, T; Rüetschi, A-S; Jaccard, D; Gabay, M; Muller, D A; Triscone, J-M; Mannhart, J

2007-08-02

442

Oxidative Reactions with Nonaqueous Enzymes  

SciTech Connect

The objective of this work is to demonstrate a proof-of-concept of enzymatic oxidative processing in nonaqueous media using alkene epoxidation and phenolic polymerization as relevant targets. This project will provide both the fundamental and applied investigations necessary to initiate the implementation of oxidative biocatalysts as commercially relevant alternatives to chemical processing in general, and to phenolic polymerizations and alkene epoxidation specifically. Thus, this work will address the Bioprocessing Solicitation Area to: (1) makes major improvements to phenolic polymerization and alkene epoxidation technologies; (2) is expected to be cost competitive with competing conventional processes; and (3) produces higher yields with less waste.

Jonathan S. Dordick; Douglas Clark; Brian H Davison; Alexander Klibanov

2001-12-30

443

Portable Ethylene Oxide Sterilization Chamber  

PubMed Central

A portable ethylene oxide sterilization chamber was designed, constructed, and tested for use in the sterilization of embolectomy catheters. The unit can accommodate catheters up to 40 inches (101.6 cm) in length and can be operated for less than 4 cents per cycle. A constant concentration of 500 mg of ethylene oxide per liter of space and holding periods of 4 and 6 hr at 43 and 22 C, respectively, were adequate when tested with B. subtilis spores. The estimated cost of construction was $165.00. If temperature control is unnecessary, the cost is approximately $80.00. Images

Songer, J. R.; Mathis, R. G.

1969-01-01

444

Solid oxide fuel cell generator  

DOEpatents

A solid oxide fuel cell generator has a pair of spaced apart tubesheets in a housing. At least two intermediate barrier walls are between the tubesheets and define a generator chamber between two intermediate buffer chambers. An array of fuel cells have tubes with open ends engaging the tubesheets. Tubular, axially elongated electrochemical cells are supported on the tubes in the generator chamber. Fuel gas and oxidant gas are preheated in the intermediate chambers by the gases flowing on the other side of the tubes. Gas leakage around the tubes through the tubesheets is permitted. The buffer chambers reentrain the leaked fuel gas for reintroduction to the generator chamber.

Draper, R.; George, R.A.; Shockling, L.A.

1993-04-06

445

Sulfides and oxides in comets  

SciTech Connect

Metal abundances associated with Sun-grazing P/comet Ikeya-Seki 1965f, the mineralogy of chrondritic interplanetary dust particles and cosmochemical affinities of Co, V, Cr, and Ni in extraterrestrial materials and probable vaporization data for nonsilicate minerals are used to evaluate the putative dearth of nonsilicates in short-period comets. It is concluded that sulfides and oxides are common, albeit minor, constituents of these comets. Sulfides and oxides can form in situ during perihelion passage in the nucleus of active short-period comets by sulfidation of Mg, Fe-silicates. 31 references.

Rietmeijer, F.J.M.

1988-08-01

446

Oxidative stress and immune thrombocytopenia.  

PubMed

Immune thrombocytopenia (ITP) is an autoimmune disorder characterized by increased platelet destruction or decreased platelet production. The mechanism of the disease has been extensively studied so that we now have a much improved understanding of the pathophysiology; however, the trigger of the autoimmunity remains unclear. More recently, oxidative stress was identified to be involved in the pathogenesis of ITP and provides a new hypothesis for the initiation of autoimmunity in patients with ITP. In this review, oxidative stress and its impact on autoimmunity, particularly ITP, will be covered. PMID:23953344

Zhang, Bing; Zehnder, James L

2013-07-01

447

Homogeneous Copper-Catalyzed Oxidations  

Microsoft Academic Search

The bioinorganic chemistry of copper has provided a stimulating background for exciting research\\u000a on homogeneous copper-catalyzed reactions in recent years, and this review starts with a brief and\\u000a concise overview of the role of copper containing active sites in metalloproteins that catalyze oxidation\\u000a or oxygenation reactions in nature. Efficient bio-inspired Cu-based catalysts for a variety of chemical\\u000a oxidative transformations have been developed over

Jarl Ivar van der Vlugt; Franc Meyer

448

Direct electrochemical oxidation of polyacrylates.  

PubMed

A promising elimination treatment of non-biodegradable organic pollutants is the direct electro-oxidation. In this work has been proposed the electrochemical elimination of polyacrylates by using boron-doped diamond (BDD) as anodic material. The complete elimination of organic contaminants has been obtained and this is the first case of successful electrochemical treatment of polymeric and bio-refractory species. The tests of the electrochemical oxidation have been conducted at constant current conditions and a complete elimination of organic species has been reached. The decrease of the COD value with time follows the behaviour of an ideal anode as in the case of low molecular organic compounds. PMID:12489259

Bellagamba, Riccardo; Comninellis, Christos; Vatistas, Nicolaos

2002-10-01

449

Emergent phenomena at oxide interfaces.  

PubMed

Recent technical advances in the atomic-scale synthesis of oxide heterostructures have provided a fertile new ground for creating novel states at their interfaces. Different symmetry constraints can be used to design structures exhibiting phenomena not found in the bulk constituents. A characteristic feature is the reconstruction of the charge, spin and orbital states at interfaces on the nanometre scale. Examples such as interface superconductivity, magneto-electric coupling, and the quantum Hall effect in oxide heterostructures are representative of the scientific and technological opportunities in this rapidly emerging field. PMID:22270825

Hwang, H Y; Iwasa, Y; Kawasaki, M; Keimer, B; Nagaosa, N; Tokura, Y

2012-01-24

450

Annular denuders for atmospheric oxidants  

SciTech Connect

Annular denuders have a wide range of applications in atmospheric chemistry. Including the collection and analysis of pollutants, the discrimination between gas phase and aerosol species, and the selective removal of pollutants. Aldehydes and photochemical oxidants including O{sub 3}, HONO{sub 2}, peroxyacetyl nitrate (PAN), and NO{sub 2} may introduce sampling artifacts when monitoring pollutants by conventional air filtration techniques. The focus of this study has been on the use of annular denuder technology for the removal of photochemical oxidants and the selective removal of PAN versus NO{sub 2}.

Williams, E.L. II; Grosjean, D. (DGA, Inc., Ventura, CA (USA))

1988-09-01

451

The Production of Nitric Oxide In Ammonia Oxidation Flames  

Microsoft Academic Search

Product compositions for ammonia\\/oxygen and ammonia\\/oxygen\\/nitrogen premixed, atmospheric pressure flames were experimentally determined. Nitric oxide concentrations in excess of equilibrium levels were observed over the entire experimental equivalence ratio range of 0.40 to 1.85.

R. F. SAWYER; W. J. McLEAN; C. M. MAES JR

1972-01-01

452

Oxidation of phenolic acids by soil iron and manganese oxides  

Microsoft Academic Search

Phenolic acids are intermediary metabolites of many aromatic chemicals and may be involved in humus formation, allelopathy, and nutrient availability. Depending on their structures, six phenolic acids were shown to react at different rates with oxidized forms of Fe and Mn in a Palouse soil (fine-silty, mixed, mesic Pachic Ultic Haploxeroll). Increasing methoxy substitution on the aromatic ring of phenolic

R. G. Lehmann; H. H. Cheng; J. B. Harsh

2008-01-01

453

Oxidation mechanisms for alloys in single-oxidant gases  

SciTech Connect

Scales formed on alloys invariably contain the alloy constituents in a ratio different from that in the alloy, owing to the differing thermodynamic tendencies of the alloy components to react with the oxidant and to differences in diffusion rates in scale and alloy phases. This complex interrelationship between transport rates and the thermodynamics of the alloy-oxidant system can be analyzed using multicomponent diffusion theory when transport-controlled growth of single or multi-layered scales occurs. In particular, the superimposition of the diffusion data on an isothermal section of the appropriate phase diagram indicates the likely morphologies of the reaction products, including the sequence of phases found in the scale, the occurrence of internal oxidation and the development of an irregular metal/scale interface. The scale morphologies on alloys are also time-dependent: there is an initial transient stage, a steady state period, and a final breakdown, the latter often related to mechanical influences such as scale adherence, spallation, thermal or mechanical stresses and void formation. Mechanical influences have a more devastating effect in alloy oxidation due to the changes in alloy surface composition during the steady state period.

Whittle, D.P.

1981-03-01

454

Nitric oxide-induced oxidation of alpha-tocopherol.  

PubMed

Exposure of alpha-tocopherol (alpha-T) to nitric oxide under aerobic conditions resulted in a complex oxidation process whose final outcome was dictated by the nature of the reaction medium. In a cyclohexane solution, a prevailing route led to a mixture of relatively unstable polar products positive to Griess reagent. On standing at room temperature these were partially converted to the novel 2,3-dimethyl-4-acetyl-4-hydroxy-5-nitroso-2-cyclopentenone derivative. Reaction of alpha-T via a secondary oxidation path led to the formation of alpha-tocopherylquinone (alpha-TQ) as well as of little amounts of the corresponding nitrite ester. A quite different product pattern was observed when the reaction was carried out on a suspension of alpha-T in 0.1 M phosphate buffer, pH 7.4. Besides a significant formation of alpha-TQ and its nitrite ester, product analysis revealed a characteristic pattern of apolar compounds consisting of a yellow dimer and a series of related oligomers. These results provide an improved chemical background to inquire into the role of alpha-T in nitric oxide-induced tissue injury. PMID:8931945

d'Ischia, M; Novellino, L

1996-10-01

455

Facile hydrothermal preparation of graphene oxide nanoribbons from graphene oxide.  

PubMed

Graphene oxide nanoribbons (GONR) with regular edges have been prepared by a facile hydrothermal method. The relatively high yield and convenient preparation of GONR eventually make graphene nanoribbons (GNR) accessible in the field of composite materials where bulk quantities of nanoribbons are required. PMID:23727666

Sun, Li-Wei; Zhao, Jun; Zhou, Li-Jing; Li, Guo-Dong

2013-07-11

456

SELECTIVE OXIDATION IN SUPERCRITICAL CARBON DIOXIDE USING CLEAN OXIDANTS  

EPA Science Inventory

We have systematically investigated heterogeneous catalytic oxidation of different substrates in supercritical carbon dioxide (SC-CO2). Three types of catagysts: a metal complex, 0.5% platinum g-alumina and 0.5% palladium g-alumina were used at a pressure of 200 bar, temperatures...

457

Epoxidation of propylene with nitrous oxide on Rb 2SO 4-modified iron oxide on silica catalysts  

Microsoft Academic Search

The catalytic activity of alkaline and earth alkaline-modified silica-supported metal oxide was investigated for epoxidizing propylene with nitrous oxide. Iron oxide gave the best results, and surprisingly chromium oxide also produced propylene oxide (PO). Unmodified iron oxide catalyst showed low oxidation activity and produced propanal (57% selectivity) in concert with small amounts of acrolein, allyl alcohol, and acetone. After modification,

Bart Moens; Hendrik De Winne; Steven Corthals; Hilde Poelman; Roger De Gryse; Vera Meynen; Pegie Cool; Bert F. Sels; Pierre A. Jacobs

2007-01-01

458

Corium Oxidation at Temperatures Above 2000 K  

SciTech Connect

A mechanistic model, based on a quasi-equilibrium analysis of oxidation reactions, is proposed for predicting high-temperature corium oxidation. The analysis suggests that oxide forming on the surface of corium containing uranium, zirconium, and iron is similar to the oxides formed on zirconium and uranium as long as there is a small percentage of unoxidized zirconium or uranium in the metallic phase. This is because of the higher affinity of zirconium and uranium for oxygen. Hence, oxidation rates and heat production rates are similar to (U,Zr) compounds until nearly all the uranium and zirconium in the corium oxidizes. Oxidation rates after this point are predicted to be similar to those implied by the oxide thickness present when the forming oxide ceases to be protective, and heat generation rates should be similar to those implied by iron oxidation, i.e., ~4% of the zirconium oxidation heating rate. The maximum atomic ratio of unoxidized iron to unoxidized liquid zirconium plus uranium for the formation of a solid protective oxide below 2800 K is estimated for a temperature, T (in Kelvin), as follows: (unoxidized iron)/(unoxidized zirconium + turanium) = (1/28){5.7/exp[-(147 061 + 12.08T log(T) - 61.03T - 0.000555T2/1.986T)]}1/2. As long as this limit is not exceeded, either zirconium or uranium metal oxidation rates and heating describe the corium oxidation rate. If this limit is exceeded, diffusion of steam to the corium surface will limit the oxidation rate, and linear time-dependent growth of a nonprotective, mostly FeO, layer will occur below the protective (Zr,U) O2 scale. When this happens, the oxidation should be at the constant rate given by the thickness of the protective layer. Heat generation should be similar to that of iron oxidation.

Hagrman, Donald Lee; Rempe, Joy Lynn

2001-02-01

459

Deactivation of metal oxides in the oxidation of carbon monoxide by interaction with sulfur oxides  

SciTech Connect

The deactivation of oxide catalysts for CO oxidation in the presence of sulfur dioxide is a result of the interaction between the catalysts and sulfur trioxide, which forms from SO/sub 2/ in the presence of oxygen. The cause of the poisoning is the formation of sulfate or strongly adsorbed SO/sub 3/ (or H/sub 2/SO/sub 4/). Sulfur trioxide can adhere strongly to the surface of the catalyst, even at temperatures higher than the decomposition temperature of sulfate.

Sultanov, M.Yu.; Al'tshel', I.S.; Makhmudova, Z.Z.

1987-08-01

460

Nitric oxide and mitochondrial respiration  

Microsoft Academic Search

Nitric oxide (NO) and its derivative peroxynitrite (ONOO?) inhibit mitochondrial respiration by distinct mechanisms. Low (nanomolar) concentrations of NO specifically inhibit cytochrome oxidase in competition with oxygen, and this inhibition is fully reversible when NO is removed. Higher concentrations of NO can inhibit the other respiratory chain complexes, probably by nitrosylating or oxidising protein thiols and removing iron from the

Guy C Brown

1999-01-01

461

Dissolution of Neptunium Oxide Residues.  

National Technical Information Service (NTIS)

This report describes the development of a dissolution flowsheet for neptunium (Np) oxide (NpO(sub 2)) residues (i.e., various NpO(sub 2) sources, HB-Line glovebox sweepings, and Savannah River National Laboratory (SRNL) thermogravimetric analysis samples...

E. A. Kyser

2009-01-01

462

NITROUS OXIDE: WHY AND HOW  

Technology Transfer Automated Retrieval System (TEKTRAN)

Nitrous oxide (N2O) is an important trace gas, which contributes to the greenhouse effect and is linked to the depletion of the stratospheric ozone layer. The atmospheric concentration of N2O is about one tenth the concentration of carbon dioxide (CO2), but its radiative force is at least 200 times ...

463

Nitric oxide, a biological effector  

Microsoft Academic Search

Nitric oxide has been used for more than 20 years as an electron paramagnetic resonance probe of oxygen binding sites in oxygen-carriers and oxygen-metabolizing metalloenzymes. The high reactivity of NO with oxygen and the superoxide anion and its high affinity for metalloproteins led biochemists to consider NO as a highly toxic compound for a living cell. This assertion has recently

Y. Henry; C. Ducrocq; J.-C. Drapier; D. Servent; C. Pellat; A. Guissani

1991-01-01

464

Catalytic regioselective oxidation of glycosides.  

PubMed

Discrimination among equals: A catalytic method for the selective oxidation of unprotected glycosides, both monosaccharides and disaccharides, has been developed. The resulting ketosaccharides are isolated in moderate to excellent yields. This approach provides a basis for protecting-group-free synthetic transformations of carbohydrates. PMID:23780519

Jäger, Manuel; Hartmann, Marcel; de Vries, Johannes G; Minnaard, Adriaan J

2013-06-18

465

Nitrous Oxide Emissions from Vehicles  

Microsoft Academic Search

Nitrous oxide is one of the trace gases that contribute to greenhouse warming as well as stratospheric ozone depletion. The role of vehicular emissions in the global N2O budget is currently in doubt due to two recent findings: (1) catalytic converters increase the levels of N2O emissions from vehicles, and (2) past measurements are questionable due to the discovery of

Jean Muhlbaier Dasch

1992-01-01

466

Perovskite catalysts for oxidative coupling  

DOEpatents

Perovskites of the structure A[sub 2]B[sub 2]C[sub 3]O[sub 10] are useful as catalysts for the oxidative coupling of lower alkane to heavier hydrocarbons. A is alkali metal; B is lanthanide or lanthanum, cerium, neodymium, samarium, praseodymium, gadolinium or dysprosium; and C is titanium.

Campbell, K.D.

1991-06-25

467

Bulk Modulus of Polyethylene Oxide.  

National Technical Information Service (NTIS)

A compressibility pressure-temperature cycle has been developed for polyethylene oxide (PEO) by which both the melting and freezing points of this polymer are easily determined. It was found that PEO supercools about 10C and that the pressure dependencies...

R. W. Warfield B. Hartmann

1972-01-01

468

Ultrasonic Absorption in Polyethylene Oxide.  

National Technical Information Service (NTIS)

Ultrasonic absorption measurements were made on high molecular weight polyethylene oxide from room temperature to above the melting point and from 3 MHz to 11 MHa. No peak in absorption was found at the melting point because the test frequencies were all ...

B. Hartmann J. Jarzynski

1970-01-01

469

Switchable windows with tungsten oxide  

Microsoft Academic Search

Tungsten oxide can change its colour reversibly upon electron injection. It can be produced by sputtering, evaporation, chemical vapour deposition or other processes. In addition to its high colouration efficiency and fast reaction kinetics, the redox potential of the electron injection is low enough to allow various switchable systems, such as electrochromic, gasochromic, photoelectrochromic or photochromic glazing. In this paper,

Andreas Georg; Anneke Georg; Wolfgang Graf; Volker Wittwer

2008-01-01

470

Molecular Structure of Titanium Oxide  

NSDL National Science Digital Library

Titanium monoxide is an odorless, golden solid generally used to make thin films. It has been proposed as an electrically conducting metallization for both microelectronics and layered piezoelectronics applications. Multi-layer coatings of TiO are used for laser mirrors, beam splitters, heat reflecting mirrors. When exposed to air, TiO oxidizes spontaneously to TiO2.

2003-06-04

471

Nickel-Base Superalloy Oxidation.  

National Technical Information Service (NTIS)

A program to determine the phenomenological oxidation behavior of five commercial nickel-base alloys (IN-100, SM-200, Inco 713C, Rene 41, and U-700) and one experimental alloy (Rene Y) is described to assure the intelligent application of these alloys and...

G. E. Wasielewski

1967-01-01

472

Decaborane as an Oxidizing Agent.  

National Technical Information Service (NTIS)

Decaborane, which has not previously been known to act as an oxidizing agent reacts with py4FeBr2(dibromo-tetrakis(pyridine) iron) in benzene to give a compound which, on treatment with tetrahydrofuran yields the high-spin tetrahedral iron(III) complex by...

N. N. Greenwood H. Schick

1969-01-01

473

Nanofabrication of Doped, Complex Oxides  

SciTech Connect

Complex oxides have many promising attributes, including wide band gaps for high temperature semiconductors, ion conducting electrolytes in fuel cells, ferroelectricity and ferromagnetism. Bulk and thin film oxides can be readily manufactured and tested however these physically hard and chemically inert materials cannot be nanofabricated by direct application of conventional methods. In order to study these materials at the nanoscale there must first be a simple and effective means to achieve the desired structures. Here we discuss the use of pulsed laser deposition at room temperature onto electron beam lithography defined templates of poly methyl methacrylate photoresist. Following a resist liftoff in organic solvents, a heat treatment was used to crystallize the nanostructures. The morphology of these structures was studied using scanning electron microscopy and atomic force microscopy. Crystallinity and composition as determined by x ray diffraction and photo-electron spectroscopy respectively is reported for thin film analogues of the nanostructured oxide. The oxide studied in this report is Nb doped SrTiO{sub 3}, which has been investigated for use as a high temperature thermoelectric material; however the approach used is not materials-dependent.

Stein, A.; Waller, G.H.; Abiade, J.T.

2012-01-01

474

Oxidative Damage in Parkinson's Disease.  

National Technical Information Service (NTIS)

The objective of the present research is to determine whether there is a coherent body of evidence implicating oxidative damage in the pathogenesis of Parkinson's Disease and the MPTP model of Parkinsonism. In the past year, we have developed a novel colu...

M. F. Beal

2001-01-01

475