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1

Persulfate oxidation of MTBE- and chloroform-spent granular activated carbon.  

PubMed

Activated persulfate (Na(2)S(2)O(8)) 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 H(2)O(2)-persulfate binary mixtures. H(2)O(2) may serve multiple roles in oxidation mechanisms including Fenton-driven oxidation, and indirect activation of persulfate through thermal or ferrous iron activation mechanisms. More frequent, lower volume applications of persulfate solution (i.e., the persulfate loading rate), higher solid/solution ratio (g GAC mL(-1) solution), and higher persulfate concentration (mass loading) resulted in greater MTBE oxidation and removal. Chloroform oxidation was more effective in URV GAC compared to F400 GAC. This study provides baseline conditions that can be used to optimize pilot-scale persulfate-driven regeneration of contaminant-spent GAC. PMID:21782339

Huling, Scott G; Ko, Saebom; Park, Saehan; Kan, Eunsung

2011-09-15

2

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. PMID:24116016

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

2013-01-01

3

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 ...

4

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

5

Kinetic Study of Polyaniline Film Formation Using Ferric Chloride\\/Ammonium Persulfate as Composite Oxidant  

Microsoft Academic Search

Polyaniline (PANI) was synthesized by in situ emulsion polymerization. The kinetics of the PANI film formation was investigated by the quartz crystal microbalance technique (QCM). PANI film doped with dodecylbenzenesulfonic acid (DBSA) was synthesized by emulsion polymerization using ferric chloride\\/ammonium persulfate (FeCl3\\/APS) as composite oxidant in the presence of a constant (0.4 T) magnetic field (MF). The results showed that the

Wen-Yi Su; Feng-Yan Liang; Li Ma

2012-01-01

6

Enhanced dewaterability of sewage sludge in the presence of Fe(II)-activated persulfate oxidation.  

PubMed

The potential benefits of Fe(II)-activated persulfate oxidation on sludge dewatering and its mechanisms were investigated in this study. Capillary suction time (CST) was used to evaluate sludge dewaterability. Both extracellular polymeric substances (EPS) and viscosity were determined in an attempt to explain the observed changes in sludge dewaterability. The optimal conditions to give preferable dewaterability characteristics were found to be persulfate (S(2)O(8)(2-)) 1.2 mmol/gVSS, Fe(II) 1.5 mmol/gVSS, and pH 3.0-8.5, which demonstrated a very high CST reduction efficiency (88.8% reduction within 1 min). It was further observed that both soluble EPS and viscosity played relatively negative roles in sludge dewatering, whereas no correlation was established between sludge dewaterability and bound EPS. Three-dimensional excitation-emission matrix (EEM) fluorescence spectra also revealed that soluble EPS of sludge were degraded and sludge flocs were ruptured by persulfate oxidation, which caused the release of water in the intracellular pace and subsequent improvement of its dewaterability. PMID:22542138

Zhen, Guangyin; Lu, Xueqin; Zhao, Youcai; Chai, Xiaoli; Niu, Dongjie

2012-07-01

7

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 (K(IP) = 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 K(IP) and k(et) 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

2013-10-10

8

A rapid spectrophotometric determination of persulfate anion in ISCO  

Microsoft Academic Search

Due to a gradual increase in the use of persulfate as an in situ chemical oxidation (ISCO) oxidant, a simple measurement of persulfate concentration is desirable to analyze persulfate distribution at designated time intervals on\\/off a site. Such a distribution helps evaluate efficacy of ISCO treatment at a site. This work proposes a spectrophotometric determination of persulfate based on modification

Chenju Liang; Chiu-Fen Huang; Nihar Mohanty; Rama Mohan Kurakalva

2008-01-01

9

Fundamentals of ISCO Using Persulfate  

Microsoft Academic Search

\\u000a \\u000a Scope  Chemistry and use of persulfate for in situ chemical oxidation of subsurface contaminants, including free radical and other reaction mechanisms, catalysts, subsurface\\u000a transport, and contaminant treatability.\\u000a \\u000a \\u000a \\u000a \\u000a Key Concepts  \\u000a \\u000a \\u000a \\u000a \\u000a • \\u000a \\u000a \\u000a \\u000a Persulfate reaction chemistry is complex. Persulfate can react through direct electron transfer or free radical reactions.\\u000a Electron transfer reactions are relatively slow and selective. Upon activation, the free radicals generated have

Benjamin G. Petri; Richard J. Watts; Aikaterini Tsitonaki; Michelle Crimi; Neil R. Thomson; Amy L. Teel

10

Thermally activated persulfate oxidation regeneration of NOM- and MTBE- 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...

11

A rapid spectrophotometric determination of persulfate anion in ISCO.  

PubMed

Due to a gradual increase in the use of persulfate as an in situ chemical oxidation (ISCO) oxidant, a simple measurement of persulfate concentration is desirable to analyze persulfate distribution at designated time intervals on/off a site. Such a distribution helps evaluate efficacy of ISCO treatment at a site. This work proposes a spectrophotometric determination of persulfate based on modification of the iodometric titration method. The analysis of absorption spectra of a yellow color solution resulting from the reaction of persulfate and iodide in the presence of sodium bicarbonate reveals an absorbance at 352 nm, without significant interferences from the reagent matrix. The calibration graph was linear in the range of persulfate solution concentration of 0-70 mM at 352 nm. The proposed method is validated by the iodometric titration method. The solution pH was at near neutral and the presence of iron activator does not interfere with the absorption measurement. Also, analysis of persulfate in a groundwater sample using the proposed method indicates a good agreement with measurements by the titration method. This proposed spectrophotometric quantification of persulfate provides a simple and rapid method for evaluation of ISCO effectiveness at a remediation site. PMID:18922560

Liang, Chenju; Huang, Chiu-Fen; Mohanty, Nihar; Kurakalva, Rama Mohan

2008-11-01

12

Kinetics of the Oxidation of Iodide Ion by Persulfate Ion in the Critical Water/Bis(2-ethylhexyl) Sodium Sulfosuccinate/n-Decane Microemulsions.  

PubMed

In this work, we studied the kinetics of the oxidation of iodide ion by persulfate ion in the critical water/bis(2-ethylhexyl) sodium sulfosuccinate (AOT)/n-decane microemulsions with the molar ratios of water to AOT being 35.0 and 40.8 via the microcalorimetry at various temperatures. It was found that the Arrhenius equation was valid for correlating experimental measurements in the noncritical region, but the slowing down effect existed significantly in the near critical region. We determined the values of the critical slowing down exponent and found it to be 0.187 ± 0.023 and 0.193 ± 0.032, respectively, which agreed well with the theoretical value of 0.207 predicted by the Griffiths-Wheeler rule for the singularity of the dimer/monomer droplet equilibrium in the critical AOT/water/n-decane microemulsions. PMID:25348218

Yin, Handi; Du, Zhongyu; Zhao, Jihua; Shen, Weiguo

2014-11-13

13

Electrokinetic delivery of persulfate to remediate PCBs polluted soils: Effect of injection spot.  

PubMed

Persulfate-based in situ chemical oxidation (ISCO) is a promising technique for the remediation of organic compounds contaminated soils. Electrokinetics (EK) provides an alternative method to deliver oxidants into the target zones especially in low permeable-soil. In this study, the flexibility of delivering persulfate by EK to remediate polychlorinated biphenyls (PCBs) polluted soil was investigated. 20% (w/w) of persulfate was injected at the anode, cathode and both electrodes to examine its transport behaviors under electrical field, and the effect of field inversion process was also evaluated. The results showed that high dosage of persulfate could be delivered into S4 section (near cathode) by electroosmosis when persulfate was injected from anode, 30.8% of PCBs was removed from the soil, and the formed hydroxyl precipitation near the cathode during EK process impeded the transportation of persulfate. In contrast, only 18.9% of PCBs was removed with the injection of persulfate from cathode, although the breakthrough of persulfate into the anode reservoir was observed. These results indicated that the electroosmotic flow is more effective for the transportation of persulfate into soil. The addition of persulfate from both electrodes did not significantly facilitate the PCBs oxidation as well as the treatment of electrical field reversion, the reinforced negative depolarization function occurring in the cathode at high current consumed most of the oxidant. Furthermore, it was found that strong acid condition near the anode favored the oxidation of PCBs by persulfate and the degradation of PCBs was in consistent with the oxidation of Soil TOC in EK/persulfate system. PMID:25193794

Fan, Guangping; Cang, Long; Fang, Guodong; Qin, Wenxiu; Ge, Liqiang; Zhou, Dongmei

2014-12-01

14

Immobilization of flavine adenine dinucleotide onto nickel oxide nanostructures modified glassy carbon electrode: fabrication of highly sensitive persulfate sensor  

Microsoft Academic Search

A simple method was used to fabricate flavin adenine dinucleotide (FAD)\\/NiOx nanocomposite on the surface of glassy carbon\\u000a (GC) electrode. Cyclic voltammetry technique was applied for deposition nickel oxide nanostructures onto GC surface. Owing\\u000a to its high biocompatibility and large surface area of nickel oxide nanomaterials with immersing the GC\\/NiOx-modified electrode\\u000a into FAD solution for a short period of time,

Abollah Salimi; Abdollah Noorbakhsh; Abolfazl Semnani

15

Field Application of a Rapid Spectrophotometric Method for Determination of Persulfate in Soil  

PubMed Central

Remediation of hydrocarbon contaminated soils can be performed both in situ and ex situ using chemical oxidants such as sodium persulfate. Standard methods for quantifying persulfate require either centrifugation or prolonged settling times. An optimized soil extraction procedure was developed for persulfate involving simple water extraction using a modified disposable syringe. This allows considerable saving of time and removes the need for centrifugation. The extraction time was reduced to only 5 min compared to 15 min for the standard approach. A comparison of the two approaches demonstrated that each provides comparable results. Comparisons were made using high (93 g kg?1 soil) and low (9.3 g kg?1 soil) additions of sodium persulfate to a petroleum hydrocarbon-contaminated soil, as well as sand spiked with diesel. Recoveries of 95±1% and 96±10% were observed with the higher application rate in the contaminated soil and spiked sand, respectively. Corresponding recoveries of 86±5% and 117±19% were measured for the lower application rate. Results were obtained in only 25 min and the method is well suited to batch analyses. In addition, it is suitable for application in a small field laboratory or even a mobile, vehicle-based system, as it requires minimal equipment and reagents. PMID:23776446

Cunningham, Colin J.; Pitschi, Vanessa; Anderson, Peter; Barry, D. A.; Patterson, Colin; Peshkur, Tanya A.

2013-01-01

16

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

2012-10-01

17

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

2013-10-01

18

Synthesis of low molecular weight alginic acid nanoparticles through persulfate treatment as effective drug delivery system to manage drug resistant bacteria  

Microsoft Academic Search

The purpose of this study was to prepare low molecular weight alginic acid (LMWA) nanoparticles by cation-induced, controlled\\u000a gelification of depolymerized alginic acid for effective drug delivery to drug resistant bacteria. The depolymerization reaction\\u000a was performed using potassium persulfate oxidation at an optimized condition. The optimized conditions for depolymerization\\u000a were anticipated to be 37°C, pH 4, 2 days reaction time,

Dipankar Ghosh; Arindam Pramanik; Narattam Sikdar; Panchanan Pramanik

2011-01-01

19

Uncovering the Mechanism of the Ag(I)/Persulfate-Catalyzed Cross-Coupling Reaction of Arylboronic Acids and Heteroarenes  

PubMed Central

The catalytic cross-coupling of arylboronic acids with pyridines through single electron oxidation provides efficient access to substituted heterocycles. Although important, there is very little known about the mechanism of the reaction and as a consequence, it is unclear if the full scope of the transformation has been realized. In this communication we present kinetic and spectroscopic evidence showing a high degree of complexity in the reaction system. The mechanism derived from these studies shows the activation of Ag(I) for reduction of persulfate and an off-cycle protodeboronation by pyridine substrate. These results provide key mechanistic insights that enable control of the off-cycle process thus providing higher efficiency and yield. PMID:23477364

Patel, Niki R.; Flowers, Robert A.

2013-01-01

20

Synthesis of per-sulfated flavonoids using 2,2,2-trichloro ethyl protecting group and their factor Xa inhibition potential  

E-print Network

Synthesis of per-sulfated flavonoids using 2,2,2-trichloro ethyl protecting group and their factor November 2004; accepted 30 November 2004 Available online 28 December 2004 Abstract--The synthesis of per-sulfated as a protecting group. The two-step synthesis results in exclusive formation of the per-sulfated product

Desai, Umesh R

21

Bidentate Dicarboxylate Capping Groups and Photosensitizers Control the Size of IrO2 Nanoparticle Catalysts for Water Oxidation  

E-print Network

are good catalysts for water photo-oxidation in persulfate/sensitizer solutions. Ruthenium tris(2(IV). In 1 M persulfate solutions in pH 5.8 Na2SiF6/NaHCO3 buffer solutions, the excited- state of the bound

22

Time-dependent proteomic iTRAQ analysis of nasal lavage of hairdressers challenged by persulfate.  

PubMed

Hairdressers are frequently exposed to bleaching powder containing persulfates, a group of compounds that may induce hypersensitivity in the airways. The mechanism causing this reaction is not clear. The aim of this study was to identify changes in the nasal lavage fluid proteome after challenge with potassium persulfate in hairdressers with bleaching powder-associated rhinitis. Furthermore, we aimed to compare their response to that of hairdressers without nasal symptoms, and atopic subjects with pollen-associated nasal symptoms. To study the pathogenesis of persulfate-associated rhinitis, the response in protein expression from the upper airway was assessed by time-dependent proteomic expression analysis of nasal lavage fluids. Samples were prepared by pooling nasal lavage fluids from the groups at different time points after challenge. Samples were depleted of high-abundant proteins, labeled with iTRAQ and analyzed by online 2D-nanoLC-MS/MS. Differences in the protein pattern between the three groups were observed. Most proteins with differentially expressed levels were involved in pathways of lipid transportation and antimicrobial activities. The major finding was increased abundance of apolipoprotein A-1, 20 min postchallenge, detected solely in the group of symptomatic hairdressers. Our results suggest there may be differences between the mechanisms responsible for the rhinitis in the symptomatic and atopic group. PMID:20815409

Kåredal, Monica H; Mortstedt, Harriet; Jeppsson, Marina C; Kronholm Diab, Kerstin; Nielsen, Jørn; Jonsson, Bo A G; Lindh, Christian H

2010-11-01

23

Removal of elemental mercury from flue gas by thermally activated ammonium persulfate in a bubble column reactor.  

PubMed

In this article, a novel technique on removal of elemental mercury (Hg(0)) from flue gas by thermally activated ammonium persulfate ((NH4)2S2O8) has been developed for the first time. Some experiments were carried out in a bubble column reactor to evaluate the effects of process parameters on Hg(0) removal. The mechanism and kinetics of Hg(0) removal are also studied. The results show that the parameters, (NH4)2S2O8 concentration, activation temperature and solution pH, have significant impacts on Hg(0) removal. The parameters, Hg(0), SO2 and NO concentration, only have small effects on Hg(0) removal. Hg(0) is removed by oxidations of (NH4)2S2O8, sulfate and hydroxyl free radicals. When (NH4)2S2O8 concentration is more than 0.1 mol/L and solution pH is lower than 9.71, Hg(0) removal by thermally activated (NH4)2S2O8 meets a pseudo-first-order fast reaction with respect to Hg(0). However, when (NH4)2S2O8 concentration is less than 0.1 mol/L or solution pH is higher than 9.71, the removal process meets a moderate speed reaction with respect to Hg(0). The above results indicate that this technique is a feasible method for emission control of Hg(0) from flue gas. PMID:25251199

Liu, Yangxian; Wang, Qian

2014-10-21

24

Study on the polarographic catalytic wave of vitamin P in the presence of persulfate and its application.  

PubMed

The polarographic catalytic wave of vitamin P in the presence of persulfate was studied by linear potential scan polarography and cyclic voltammetry. Vitamin P yielded a single reduction wave in acidic aqueous solution, which was ascribed to a 2e(-), 2H(+) reduction of the carbonyl group in the C-4 position. Actually, the carbonyl group C=O first underwent a 1e(-), 1H(+) reduction to form a neutral free radical, and the further 1e(-), 1H(+) reduction of the free radical was simultaneous with its following chemical reactions. When S(2)O(2-)(8) was present, the free radical of vitamin P was oxidized by both S(2)O(2-)(8) and its reduction intermediate, the sulfate radical anion SO(*-)(4), to regenerate the original, which resulted in the production of a polarographic catalytic wave of vitamin P. Based on this catalytic wave, a novel method for the determination of vitamin P was proposed. In 0.02 M tartaric acid-sodium tartrate (pH 3.3) buffer containing 5.0 x 10(-3) M K(2)S(2)O(8), the peak potential of the catalytic wave was -1.42 V (vs SCE) and the peak current was rectilinear to the vitamin P concentration in the range of 8.0 x 10(-9)-1.0 x 10(-6) M (r = 0.9994, n = 13). The catalytic wave of 2.0 x 10(-7) M vitamin P enhanced the polarographic current 70 times compared with the corresponding reduction wave. The detection limit was 2.0 x 10(-9) M, and the relative standard deviation at the 2.0 x 10(-7) M level was 0.7% (n = 15). The proposed method was used for the determination of vitamin P content in the pharmaceutical preparation of tablets and the medicinal plant Sophora japonica L. without previous separation. PMID:12009698

Song, Jun Feng; He, Ping; Guo, Wei

2002-05-15

25

Persistence of Asthmatic Response after Ammonium Persulfate-Induced Occupational Asthma in Mice  

PubMed Central

Introduction Since persulfate salts are an important cause of occupational asthma (OA), we aimed to study the persistence of respiratory symptoms after a single exposure to ammonium persulfate (AP) in AP-sensitized mice. Material and Methods BALB/c mice received dermal applications of AP or dimethylsulfoxide (DMSO) on days 1 and 8. On day 15, they received a single nasal instillation of AP or saline. Airway hyperresponsiveness (AHR) was assessed using methacholine provocation, while pulmonary inflammation was evaluated in bronchoalveolar lavage (BAL), and total serum immunoglobulin E (IgE), IgG1 and IgG2a were measured in blood at 1, 4, 8, 24 hours and 4, 8, 15 days after the single exposure to the causal agent. Histological studies of lungs were assessed. Results AP-treated mice showed a sustained increase in AHR, lasting up to 4 days after the challenge. There was a significant increase in the percentage of neutrophils 8 hours after the challenge, which persisted for 24 hours in AP-treated mice. The extent of airway inflammation was also seen in the histological analysis of the lungs from challenged mice. Slight increases in total serum IgE 4 days after the challenge were found, while IgG gradually increased further 4 to 15 days after the AP challenge in AP-sensitized mice. Conclusions In AP-sensitized mice, an Ig-independent response is induced after AP challenge. AHR appears immediately, but airway neutrophil inflammation appears later. This response decreases in time; at early stages only respiratory and inflammatory responses decrease, but later on immunological response decreases as well. PMID:25303285

Olle-Monge, Marta; Munoz, Xavier; Vanoirbeek, Jeroen A. J.; Gomez-Olles, Susana; Morell, Ferran; Cruz, Maria-Jesus

2014-01-01

26

PERFORMANCE OF A STIRLING ENGINE POWERED HEAT ACTIVATED HEAT PUMP  

E-print Network

the attractiveness of the present concept. SYSTEM DESCRIPTION The heat activated heat pump (HAHP) employs a primePERFORMANCE OF A STIRLING ENGINE POWERED HEAT ACTIVATED HEAT PUMP W. D. C. Richards and W. L. Auxer General Electric Company Space Division King of Prussia, Pa. ABSTRACT A heat activated heat pump (HAHP

Oak Ridge National Laboratory

27

slowly released, persulfate, methyl tertiary-butyl ether(MTBE), benzene, in-situ oxidative wall.  

E-print Network

??Contamination of soil/groundwater supplies by gasoline and other petroleum-derived hydrocarbons released from underground storage tanks (USTs) is a serious and widespread environmental problem. Corrosion, ground… (more)

Kuo, Yu-chia

2009-01-01

28

Photocatalytic synthesis of dihydrobenzofurans by oxidative [3+2] cycloaddition of phenols.  

PubMed

We report a protocol for oxidative [3+2] cycloadditions of phenols and alkenes applicable to the modular synthesis of a large family of dihydrobenzofuran natural products. Visible-light-activated transition metal photocatalysis enables the use of ammonium persulfate as an easily handled, benign terminal oxidant. The broad range of organic substrates that are readily oxidized by photoredox catalysis suggests that this strategy may be applicable to a variety of useful oxidative transformations. PMID:25155300

Blum, Travis R; Zhu, Ye; Nordeen, Sarah A; Yoon, Tehshik P

2014-10-01

29

Pentachlorophenol removal from aqueous solutions by microwave/persulfate and microwave/H2O2: a comparative kinetic study  

PubMed Central

Pentachlorophenol (PCP) is one of the most fungicides and pesticides used in wood protection. Poisoning from PCP may be happened in dermal absorption, and respiration or ingestion. With regard to health and environmental effects of PCP, many methods were studied for its removal. Microwave assisted other methods are environmental friendly, safety, and economical method, therefore, in this study; a modified domestic microwave assisted hydrogen peroxide (MW/H2O2) and sodium persulfate (MW/SPS) was used for PCP removal from aqueous solutions. PCP removal rate was measured under different factors such as pH, energy intensity, SPS, H2O2 concentration, Tert- butyl alcohol (TBA) and chemical oxygen demand (COD). The concentration changes of PCP were determined using spectrophotometer and HPLC spectra, respectively. The best removal PCP rate obtained in condition of pH of 11, 0.02 mol L?1 of SPS, 0.2 mol L?1 of H2O2 and energy intensity of 600 W. Moreover, COD removals in MW/H2O2 and MW/SPS process were 83% and 94%, respectively, also TBA test decreased 15% and 3% of PCP removal in MW/SPS and MW/H2O2 processes respectively. Experimental results indicated that sulfate radical was stronger than hydroxyl radical and examinations order reaction was in first order. In this study, was cleared that MW/SPS process was more effective than MW/H2O2 process in PCP removal. PMID:25018879

2014-01-01

30

ERDC/ELTR-11-3 Innovative Technology Advocate Formerly Used Defense Sites  

E-print Network

to investigate the use of persulfate to treat PCBs in solution. Heat-activated (50°C) sodium persulfate (Na2S2O8) removed >90% of the PCBs (Aroclor 1254), but lime-activated persulfate was ineffective. A final study of the subject Alaska soils. Some promise might be found for heat-activated persulfate treatment, although

US Army Corps of Engineers

31

The heat-activated stapes prosthesis 'SMart' Piston: technique and preliminary results.  

PubMed

Since 2003 we are using in our stapedotomies the Nitinol 'Smart' Piston. This prosthesis has a Teflon 'vestibular' end and a wire shaft made by Nitinol, with a heat activated self-crimping loop. Nitinol is an alloy of Nickel + Titanium, belonging to the class of the so-called smart materials, i.e. materials with shape-memory and superelastic properties. Nitinol is lightweight and highly biocompatible thanks to the thin layer of Titanium oxide covering the Nickel surface. The special advantage of this piston is that the loop grips by itself very uniformly and quite tightly around the incudal process or the malleus handle when a minimal heating (about 60 degrees C) is applied using a disposable heater ('Thermal Tip'). This piston was successfully used in our Department between 2003 and 2004 in a first group of 42 cases of stapedotomy and in 7 cases of malleostapedotomy. The shape and the uniformity of the loop grip was controlled by examining fresh temporal bone specimens by S.E.M. (x21 / 166) and in all specimens the loop was uniformly surrounding the ossicle, without 'dead' spaces. It is our feeling that this prosthesis is very useful in stapes surgery for at least two reasons: 1. because it improves the quality of the interface 'piston loop/long process of incus'; 2. because the duration of the procedure is reduced. PMID:17245045

Babighian, Gregorio; Fontana, Marco; Caltran, Silvia; Ciccolella, Michele; Amadori, Maurizio; De Zen, Michela

2007-01-01

32

The Sulfate Radical Anion is a New Reagent for Fast Photochemical Oxidation of Proteins (FPOP)†  

PubMed Central

The focus is to expand the original design of fast photochemical oxidation of proteins (FPOP) and introduce SO4?•, generated by 248 nm homolysis of low mM levels of persulfate, as a radical reactant in protein footprinting. FPOP is a chemical footprinting approach to footprinting proteins and protein complexes by “snapshot” reaction with free radicals. The radical used until now is the OH radical, and it provides a measure of residue-resolved solvent accessibility of the native protein. We show that FPOP can accommodate other reagents, increasing its versatility. The new persulfate FPOP system is a potent, non-specific, and tunable footprinting method; 3–5 times less persulfate is needed to give the same global levels of modification as seen with OH radicals. Although solvent-exposed His and Tyr residues are more reactive with SO4?• than with •OH, oxidation of apomyoglobin and calmodulin shows that •OH probes smaller accessible areas than SO4?•, with the possible exception of histidine. His64, an axial ligand in the heme-binding pocket of apomyoglobin, is substantially up-labeled by SO4?• relative to •OH. Nevertheless, the kinds of modification and residue selectivity for both reagent radicals are strikingly similar. Thus, the choice of these reagents relies on the physical properties, particularly the membrane permeability, of the radical precursors. PMID:20738105

Gau, Brian C.; Chen, Hao; Zhang, Yun

2010-01-01

33

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

Microsoft Academic Search

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

P. D. Fairchild; C. D. West

1982-01-01

34

SYSTEM PERFORMANCE OF A STIRLING ENGINE POWERED HEAT ACTIVATED HEAT PUMP  

E-print Network

AUG 1979 SYSTEM PERFORMANCE OF A STIRLING ENGINE POWERED HEAT ACTIVATED HEAT PUMP W. D. Richards W to supplement the heating capacity in addition to the heat pump effect would enable a HAHP system- totype 1 was the first attempt to test the Stirling/Rankine HAHP on a system level, with heat pump

Oak Ridge National Laboratory

35

Carbon isotopic analysis of dissolved organic carbon in produced water brines by wet chemical oxidation and cavity ring-down spectroscopy  

NASA Astrophysics Data System (ADS)

We have adapted the Picarro iTOC CRDS isotope analyzer for analysis of produced water brines via wet chemical persulfate oxidation. In particular, we developed strategies and techniques for overcoming the limitation imposed by low oxidation efficiencies due to the chloride ion interference with persulfate oxidation. These techniques are important for understanding the origin of dissolved organic carbon in subsurface fluids from oilfields, as a tracer of fracking fluids in groundwater, and in interpreting changes in groundwater DOC as a result of microbial activity including oil biodegradation or microbially enhanced oil recovery. We describe the limitations of this new instrument for the analysis of DOC in brines including sample requirements, matrix effects, and the effect of DOC composition on reaction efficiency and isotopic measurements. We compare strategies including anion exchange cartridges, persulfate reactant concentrations, and reaction time. The CRDS analysis of DOC in brines is a useful tool for understanding the origin and fate of DOC and is a potentially powerful tool to identifiy evidence of contamination due to hydrofracturing chemicals that have a distinctive carbon isotopic signature relative to natural brine.

Thomas, B.; Conaway, C.; Kharaka, Y. K.; Saad, N.

2012-12-01

36

A High-Throughput Optical Screening Method for the Optimization of Colloidal Water Oxidation Catalysts  

E-print Network

containing tris(2,2-bipyridyl)ruthenium(II) (Ru(bpy)3 2+ ) and persulfate. The array of reaction solutions evolution from Ru(bpy)3 2+, using persulfate as a sacrificial electron acceptor, have been achieved using Ir

37

Magnetoresistive polyaniline/multi-walled carbon nanotube nanocomposites with negative  

E-print Network

with Cr(VI) as oxidant and MWNTs/PANI nanocomposites with ammonium persulfate (APS) as oxidant, a room% is reported in 5 wt% MWNTs/ PANI nanocomposites synthesized with ammonium persulfate (APS) as oxidant.9

Guo, John Zhanhu

38

Polyaniline shell cross-linked Fe3O4 magnetic nanoparticles for heat activated killing of cancer cells.  

PubMed

Superparamagnetic Fe3O4 nanoparticles are appealing materials for heat activated killing of cancer cells. Here, we report a novel method to enhance the heat activated killing of cancer cells under an AC magnetic field (AMF) by introducing a polyaniline impregnated shell onto the surface of Fe3O4 nanoparticles. These polyaniline shell cross-linked magnetic nanoparticles (PSMN) were prepared by in situ polymerization of aniline hydrochloride on the surface of carboxyl PEGylated Fe3O4 nanoparticles. XRD and TEM analyses revealed the formation of single phase inverse spinel Fe3O4 nanoparticles of a size of about 10 nm. The successful growth of the polyaniline shell on the surface of carboxyl PEGylated magnetic nanoparticles (CPMN) is evident from FTIR spectra, DLS, TGA, zeta-potential and magnetic measurements. Both CPMN and PSMN show good colloidal stability, superparamagnetic behavior at room temperature and excellent heating efficacy under AMF. It has been observed that the heating efficacy of PSMN under AMF was slightly reduced as compared to that of CPMN. The enhanced toxicity of PSMN to cancer cells under AMF suggests their strong potential for magnetic hyperthermia. Furthermore, PSMN shows high loading affinity for an anticancer drug (doxorubicin), its sustained release and substantial internalization in tumor cells. PMID:24948377

Rana, Suman; Jadhav, Neena V; Barick, K C; Pandey, B N; Hassan, P A

2014-08-28

39

INSTITUTE OF PHYSICS PUBLISHING NANOTECHNOLOGY Nanotechnology 15 (2004) 15241529 PII: S0957-4484(04)83271-9  

E-print Network

persulfate as an oxidant, or alternatively in an enzymatic oxidation by hydrogen peroxide using horseradish persulfate, polyaniline can be grown on DNA templates already immobilized on a surface. Current

Ludwig-Maximilians-Universität, München

40

Persulfate Persistence and Treatability of Gasoline Compounds.  

E-print Network

??Petroleum hydrocarbons (PHCs) such as gasoline are ubiquitous organic compounds present at contaminated sites throughout the world. Accidental spills and leakage from underground storage tanks… (more)

Sra, Kanwartej Singh

2010-01-01

41

Degradation of Guar-Based Fracturing Gels: A Study of Oxidative and Enzymatic Breakers  

E-print Network

........................................................... 47 4.3.1.1 Ammonium Persulfate ............................................... 47 4.3.1.2. Magnesium Peroxide ................................................ 55 4.3.1.3. Sodium Bromate... ...................................................................... 74 4.4. Breaker Activity Curves (S-Curves) ...................................................... 79 4.4.1. Ammonium Persulfate ............................................................. 79 4.4.2. Magnesium Peroxide...

Sarwar, Muhammad Usman

2012-02-14

42

Degradation of acid red 97 dye in aqueous medium using wet oxidation and electro-Fenton techniques.  

PubMed

Degradation of the acid red 97 dye using wet oxidation, by different oxidants, and electro-Fenton systems was investigated in this study. The oxidation effect of different oxidants such as molecular oxygen, periodate, persulfate, bromate, and hydrogen peroxide in wet oxidation system was compared. Mineralization of AR97 with periodate appeared more effective when compared with that of the other oxidants at equal initial concentration. When 5 mM of periodate was used, at the first minute of the oxidative treatment, the decolorization percentage of AR97 solution at 150 and 200 degrees C reached 88 and 98%, respectively. The total organic carbon removal efficiency at these temperatures also reached 60 and 80%. The degradation of AR97 was also studied by electro-Fenton process. The optimal current value and Fe(2+) concentration were found to be 300 mA and 0.2 mM, respectively. The results showed that electro-Fenton process can lead to 70 and 95% mineralization of the dye solution after 3 and 5h giving carboxylic acids and inorganic ions as final end-products before mineralization. The products obtained from degradation were identified by GC/MS as 1,2-naphthalenediol, 1,1'-biphenyl-4-amino-4-ol, 2-naphthalenol diazonium, 2-naphthalenol, 2,3-dihydroxy-1,4-naphthalenedion, phthalic anhydride, 1,2-benzenedicarboxylic acid, phthaldehyde, 3-hydroxy-1,2-benzenedicarboxylic acid, 4-amino-benzoic acid, and 2-formyl-benzoic acid. PMID:20074850

Kayan, Berkant; Gözmen, Belgin; Demirel, Muhammet; Gizir, A Murat

2010-05-15

43

MARINE ECOLOGY PROGRESS SERIES Mar Ecol Prog Ser  

E-print Network

persulfate or chromic acid (Strickland & Parsons 1968) or other oxidizing agents, or irradiation of samples persulfate digestion since Menzel & Corwin (1965) introduced this method. Phosphorus is converted to PO4, replicate seston samples for P undergo a separate, persulfate digestion and are analyzed by colorimetric

44

A direct instrument comparison for measurement of total dissolved nitrogen in seawater  

E-print Network

exercises, samples were also run by the more established persulfate oxidation method. There was fairly good samples in the Homelab exercise. In both cases, the persulfate method values were similar to those. The persulfate method gave slightly higher TDN concentrations for the field samples than the Shimadzu HTC

Seitzinger, Sybil

45

NF-TiO? photocatalysis of amitrole and atrazine with addition of oxidants under simulated solar light: emerging synergies, degradation intermediates, and reusable attributes.  

PubMed

In order to investigate sustainable alternatives to current water treatment methods, the effect of NF-titania film thickness and subsequent photocatalysis in combination with oxidants was examined under simulated solar light. Such a combination presents a theoretical possibility for a synergistic interaction between the photocatalyst and the oxidant (activation of the oxidant by the catalyst under conditions under which it may not conventionally be activated). To investigate, peroxymonosulfate (PMS) and persulfate (PS) were used as oxidants, and two pesticides, amitrole and atrazine, were used as target contaminants. In the absence of a film, activation of PMS under simulated solar conditions is demonstrated by removal of atrazine, whereas PS provided minimal removal, suggesting inefficient activation. Combining photocatalytic films with PMS and PS manifested synergies for both oxidants. The effect was most pronounced for PS since PMS already underwent significant activation without the photocatalyst. Amitrole degradation results indicated a lack of removal of amitrole by activated PS alone, suggesting that this sulfate radical-based treatment technology may be ineffective for the removal of amitrole. The NF-TiO? films demonstrated reusability under solar light both with and without oxidants. Finally, the degradation intermediates were analyzed, and a new intermediate appeared upon incorporating oxidants into the system. PMID:23811632

Andersen, Joel; Pelaez, Miguel; Guay, Lisa; Zhang, Zhaohong; O'Shea, Kevin; Dionysiou, Dionysios D

2013-09-15

46

Siderite, oxidation, and neutralization potential determination  

E-print Network

reactions of FeCO? under various testing conditions as related to NP determination as well as accuracy of the NP method. The effects of hydrogen peroxide (H?O?), potassium persulfate (K?S?O?), and potassium permanganate (KMnO?) on the NP of mixed overburden...

Porter, Elizabeth Brooke

2012-06-07

47

Water oxidation by lambda-MnO2: catalysis by the cubical Mn4O4 subcluster obtained by delithiation of spinel LiMn2O4.  

PubMed

Nanocrystalline spinel LiMn(2)O(4) has been prepared and treatment of LiMn(2)O(4) with dilute nitric acid solution resulted in the delithiation of the framework, while maintaining the spinel structure, lambda-MnO(2). LiMn(2)O(4) is not a catalyst for water oxidation. Upon removal of the lithium, the cubical Mn(4)O(4) cores become active sites for oxidizing water to molecular oxygen, which was investigated with the photochemical [Ru(2+)(2,2'-bpy)(3)]/persulfate system at pH 5.8. The nanosize lambda-MnO(2) obtained from the nanocrystalline LiMn(2)O(4), which was synthesized by the citrate route, shows a significantly higher water oxidation catalytic activity (Turnover Frequency: 3 x 10(-5) mol O(2)/s/mol Mn) than that obtained via solid state reaction with micrometer and irregular particle sizes (Turnover Frequency: 5 x 10(-6) mol O(2)/s/mol Mn). PMID:20672802

Robinson, David M; Go, Yong Bok; Greenblatt, Martha; Dismukes, G Charles

2010-08-25

48

Visible-Light-Induced Water Oxidation Mediated by a Mononuclear-Cobalt(II)-Substituted Silicotungstate.  

PubMed

A mononuclear-cobalt(II)-substituted silicotungstate, K10 [Co(H2 O)2 (?-SiW10 O35 )2 ]?23?H2 O (POM-1), has been evaluated as a light-driven water-oxidation catalyst. With in situ photogenerated [Ru(bpy)3 ](3+) (bpy=2,2'-bipyridine) as the oxidant, quite high catalytic turnover number (TON; 313), turnover frequency (TOF; 3.2?s(-1) ), and quantum yield (?QY ; 27?%) for oxygen evolution at pH?9.0 were acquired. Comparison experiments with its structural analogues, namely [Ni(H2 O)2 (?-SiW10 O35 )2 ](10-) (POM-2) and [Mn(H2 O)2 (?-SiW10 O35 )2 ](10-) (POM-3), gave the conclusion that the cobalt center in POM-1 is the active site. The hydrolytic stability of the title polyoxometalate (POM) was confirmed by extensive experiments, including UV/Vis spectroscopy, linear sweep voltammetry (LSV), and cathodic adsorption stripping analysis (CASA). As the [Ru(bpy)3 ](2+) /visible light/sodium persulfate system was introduced, a POM-photosensitizer complex formed within minutes before visible-light irradiation. It was demonstrated that this complex functioned as the active species, which remained intact after the oxygen-evolution reaction. Multiple experimental parameters were investigated and the catalytic activity was also compared with the well-studied POM-based water-oxidation catalysts (i.e., [Co4 (H2 O)2 (?-PW9 O34 )2 ](10-) (Co4 -POM) and [Co(III) Co(II) (H2 O)W11 O39 ](7-) (Co2 -POM)) under optimum conditions. PMID:25145473

Xiang, Rui; Ding, Yong; Zhao, Junwei

2014-11-01

49

The inventory, seasonality and stoichiometry of the major phosphorus pools in the Sargasso Sea  

E-print Network

of the UV method and the persulfate method of Koroleff (1983), Ridal and Moore (1990) found that the standard protocols of these methods did not completely convert the DOP from marine samples and they recommended a 39 combination of both methods... for measuring TDP. Ormaza-Gonzalez and Statham (1996) compared five TDP methods including the UV and persulfate methods, along with a combustion method, a nitrate oxidation method and an alkaline persulfate method. Their recommended method was the nitrate...

Case, Darin A

2012-06-07

50

Magnesium Oxide  

MedlinePLUS

... different reasons. Some people use it as an antacid to relieve heartburn, sour stomach, or acid indigestion. ... stomach.Do not take magnesium oxide as an antacid for longer than 2 weeks unless your doctor ...

51

Oxidative stress  

PubMed Central

Considerable evidence implicates oxidative stress in the pathophysiology of many complications of human pregnancy, and this topic has now become a major focus of both clinical and basic science research. Oxidative stress arises when the production of reactive oxygen species overwhelms the intrinsic anti-oxidant defences. Reactive oxygen species play important roles as second messengers in many intracellular signalling cascades aimed at maintaining the cell in homeostasis with its immediate environment. At higher levels, they can cause indiscriminate damage to biological molecules, leading to loss of function and even cell death. In this chapter, we will review how reactive oxygen species are generated and detoxified in the human placenta, and what roles they may play at homeostatic concentrations. We will then consider their involvement in normal placental development, and in complications ranging from miscarriage to pre-eclampsia and premature rupture of the membranes. PMID:21130690

Burton, Graham J.; Jauniaux, Eric

2011-01-01

52

Oxidation catalyst  

DOEpatents

The present invention generally relates to catalyst systems and methods for oxidation of carbon monoxide. The invention involves catalyst compositions which may be advantageously altered by, for example, modification of the catalyst surface to enhance catalyst performance. Catalyst systems of the present invention may be capable of performing the oxidation of carbon monoxide at relatively lower temperatures (e.g., 200 K and below) and at relatively higher reaction rates than known catalysts. Additionally, catalyst systems disclosed herein may be substantially lower in cost than current commercial catalysts. Such catalyst systems may be useful in, for example, catalytic converters, fuel cells, sensors, and the like.

Ceyer, Sylvia T. (Cambridge, MA); Lahr, David L. (Cambridge, MA)

2010-11-09

53

Oxidative stress  

Microsoft Academic Search

The early involvement of free radicals in the evolution of life may explain their ubiquitous presence and vital physiological role. Imbalance between protection against free radicals and their generation, explains the likely association of various diseases with toxic oxygen species. An elaborate defence system against oxygen-free radicals exists. The effects of oxidative stress are manifold. Direct demonstration of oxygen radicals

A. Bast; R. J. A. Goris

1989-01-01

54

ALTERNATIVE OXIDANTS  

EPA Science Inventory

This chapter reports on the efforts of the USEPA to study chloramines, chlorine dioxide and ozone as alternative oxidants/disinfectants to chlorine for the control of disinfection by-rpdocuts (DBPs) in drinking water. It examines the control of DBPs like trihalomethanes and haloa...

55

Effects of oxidizing adulterants on detection of 11-nor-delta9-THC-9-carboxylic acid in urine.  

PubMed

Bleach, nitrite, chromate, and hydrogen peroxide-peroxidase are effective urine adulterants used by the illicit drug users to conceal marijuana-positive results. Methods for detecting nitrite and chromate are available. Effects of other oxidizing agents that could possibly be used as adulterants and are difficult to detect or measure are presented in this report. Urine samples containing 40 ng/mL of 11-nor-delta9-THC-9-carboxylic acid (THC-acid) were treated with 10 mmol/L of commonly available oxidizing agents. Effects of horseradish peroxidase of activity 10 unit/mL and extracts from 2.5 g of red radish (Raphanus sativus, Radicula group), horseradish (Armoracia rusticana), Japanese radish (Raphanus sativus, Daikon group), and black mustard seeds (Brassica nigra), all with 10 mmol/L of hydrogen peroxide, were also examined. After 5 min, 16 h and 48 h of exposure at room temperature (23 degrees C) the specimens were tested by a gas chromatographic-mass spectrometric method for THC-acid. A control group treated with sodium hydrosulfite to reduce the oxidants, was also tested to investigate the effect of oxidizing agents on THC-acid in the extraction method. THC-acid was lost completely in the extraction method when treated with chromate, nitrite, oxone, and hydrogen peroxide/ferrous ammonium sulfate (Fenton's reagent). Some losses were also observed with persulfate and periodate (up to 25%). These oxidants, and other oxidizing agents like permanganate, periodate, peroxidase, and extracts from red radish, horseradish, Japanese radish and black mustard seeds destroyed most of the THC-acid (> 94%) within 48 h of exposure. Chlorate, perchlorate, iodate, and oxychloride under these conditions showed little or no effect. Complete loss was observed when THC-acid was exposed to 50 mmol/L of oxychloride for 48 h. Several oxidizing adulterants that are difficult to test by the present urine adulterant testing methods showed considerable effects on the destruction of THC-acid. The time and temperature for these effects were similar to those used by most laboratories to collect and test specimens. In several cases, the loss of THC-acid was > 94%. PMID:12423000

Paul, Buddha D; Jacobs, Aaron

2002-10-01

56

Oxidation Using Ruthenium Catalysts  

Microsoft Academic Search

Among the catalysts which have potential for use in selective oxidations, ruthenium takes a special position owing to its versatility. Ruthenium can catalyse numerous oxidative transformations: the oxidation of alkanes, the cleavage of double bonds, the asymmetric epoxidation of alkenes, the oxidation of alcohols and ethers and the oxidation of amines and amides. In the field of alcohol, ether and

I. W. C. E. Arends; T. Kodama; R. A. Sheldon

57

Management of produced water in oil and gas operations  

E-print Network

. The sample is acidified to purge the TIC. Sodium persulfate, a strong oxidizer is added next. The oxidant quickly reacts with organic carbon in the sample at 100oC to form carbon dioxide. When the oxidation reaction is completed, the carbon dioxide... contain less than 200 ppb of TOC. We used distilled or deionized water. Sodium persulfate (100 g/L): It is prepared by dissolving 100 g sodium persulfate into reagent water (1 liter total volume). The solution is stirred and then heated in a bottle...

Patel, Chirag V.

2005-02-17

58

[Nitric oxide--oxidant or antioxidant?].  

PubMed

Nitric oxide (NO), as a free radical, seems to be a potential antioxidant. It takes part in termination of lipid peroxidation reactions. It can be also an oxidant, particularly in indirect reactions with oxygen molecules or superoxide anion. PMID:16529066

Kowalczyk, Edward; Kopff, Anna; Kopff, Maria; Fija?kowski, Pawe?; B?aszczyk, Jan

2005-01-01

59

Asphalt Oxidation Kinetics and Pavement Oxidation Modeling  

E-print Network

simplified model. And the experimental effort and time to obtain these kinetics parameters were significantly reduced. Furthermore, to investigate the mechanism of asphalt oxidation, two antioxidants were studied on their effectiveness. Asphalt oxidation...

Jin, Xin

2012-07-16

60

Selective methane oxidation over promoted oxide catalysts  

SciTech Connect

Objective was to selectively oxidize methane to C{sub 2} hydrocarbons and to oxygenates, in particular formaldehyde and methanol, in high space time yields under relatively mild reaction conditions. Results in this document are reported under the headings: methane oxidation over silica, methane oxidation over Sr/La{sub 2}O{sub 3} catalysts, and oxidative coupling of methane over sulfate-doped Sr/La{sub 2}O{sub 3} catalysts. 24 refs, 10 figs, 4 tabs.

Klier, K.; Herman, R.G.

1993-12-31

61

Metabolism of gossypol in chickens  

E-print Network

), which is an adaptation of the Warburg flask, was u, sed along with Van Slyke's reagen, t and persulfate reagent as well as perchloric acid as oxidation agents to liberate the CO2. A sample of labeled gossypol dissolved in toluene and another... dissolved in methanol were oxidized with the C02 being trapped in hyamine hydroxide and counted directly after the addition of the solvent- phosphor solution. Chromic acid, Van Slyke's reagent, and persulfate reagent were used to oxidize a gossypol...

Cronin, John Thomas, II

2012-06-07

62

Solvent free permanganate oxidations  

Microsoft Academic Search

The oxidations of organic compounds by permanganate under solvent free conditions have been studied. Thiols and primary aromatic amines undergo oxidative coupling reactions to give disulfides and diazenes, respectively, sulfides are oxidized to sulfones, primary and secondary alcohols are converted to aldehydes and ketones, 1,4-diols and cyclic ethers give lactones and arenes are oxidized to the corresponding ?-ketones. The experimental

Ahmad Shaabani; Donald G. Lee

2001-01-01

63

Thermally exfoliated graphite oxide  

NASA Technical Reports Server (NTRS)

A modified graphite oxide material contains a thermally exfoliated graphite oxide with a surface area of from about 300 sq m/g to 2600 sq m/g, wherein the thermally exfoliated graphite oxide displays no signature of the original graphite and/or graphite oxide, as determined by X-ray diffraction.

Prud'Homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor); Abdala, Ahmed (Inventor)

2011-01-01

64

Methane oxidation over catalytic copper oxides nanowires  

Microsoft Academic Search

Copper oxide (CuO) is one of the promising catalysts for the catalytic oxidation of methane (CH4). Previous studies have focused on CuO nanoparticles (NPs) dispersed on other supporting oxides. However, aggregation of CuO NPs under large loadings and solid state reactions between CuO and supports hinder the understanding and further improvement of the catalytic properties of CuO. Here, we report

Yunzhe Feng; Pratap M. Rao; Dong Rip Kim; Xiaolin Zheng

2011-01-01

65

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. 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

2011-01-01

66

40 CFR 268.42 - Treatment standards expressed as specified technologies.  

...2) chlorine; (3) chlorine dioxide; (4) ozone or UV (ultraviolet light) assisted ozone; (5) peroxides; (6) persulfates; (7) perchlorates; (8) permangantes; and/or (9) other oxidizing reagents of equivalent efficiency,...

2014-07-01

67

Nitric oxide, oxidants, and protein tyrosine nitration  

Microsoft Academic Search

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

Rafael Radi

2004-01-01

68

Oxidative Stress, Nitric Oxide, and Diabetes  

PubMed Central

In the recent decades, oxidative stress has become focus of interest in most biomedical disciplines and many types of clinical research. Increasing evidence from research on several diseases show that oxidative stress is associated with the pathogenesis of diabetes, obesity, cancer, ageing, inflammation, neurodegenerative disorders, hypertension, apoptosis, cardiovascular diseases, and heart failure. Based on this research, the emerging concept is that oxidative stress is the “final common pathway”, through which risk factors of several diseases exert their deleterious effects. Oxidative stress causes a complex dysregulation of cell metabolism and cell-cell homeostasis. In this review, we discuss the role of oxidative stress in the pathogenesis of insulin resistance and beta-cell dysfunction. These are the two most relevant mechanisms in the pathophysiology of type 2 diabetes, and in the pathogenesis of diabetic vascular complications, the leading cause of death in diabetic patients. PMID:20703435

Pitocco, Dario; Zaccardi, Francesco; Di Stasio, Enrico; Romitelli, Federica; Santini, Stefano A.; Zuppi, Cecilia; Ghirlanda, Giovanni

2010-01-01

69

Cyclic oxidation of superalloys  

NASA Technical Reports Server (NTRS)

The development of mathematical/computer models of cyclic oxidation in high-temperature alloys is described. The acceleration of oxidation attack caused by the spalling of protective oxide scales is discussed. The COREST paralinear model based on empirical data, designed by Barrett and Pressler, is found to be of limited value. Basic research on the spalling process in different alloy systems is reviewed, and the phenomenon is characterized: occurring mainly within the oxide, it is caused by the different thermal expansion coefficients of oxide and metal and is a linear function of the total retained oxide. This information has been used in the development of the discrete oxide-spall model COSP and in its modification by addition of a diffusion-zone-profile model to predict the failure of components (Heckel and Nesbitt, unpublished). The COSP model is shown to produce good predictions of cyclic oxidation under a variety of conditions, using data from simple isothermic tests.

Lowell, C. E.; Smialek, J. L.; Barrett, C. A.

1983-01-01

70

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

71

Bridged graphite oxide materials  

NASA Technical Reports Server (NTRS)

Bridged graphite oxide material comprising graphite sheets bridged by at least one diamine bridging group. The bridged graphite oxide material may be incorporated in polymer composites or used in adsorption media.

Herrera-Alonso, Margarita (Inventor); McAllister, Michael J. (Inventor); Aksay, Ilhan A. (Inventor); Prud'homme, Robert K. (Inventor)

2010-01-01

72

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

73

Solid Oxide Fuel Cell  

NSDL National Science Digital Library

This page is an introduction to the Solid Oxide fuel cell. It uses flash software to explain in greater detail what the Solid Oxide fuel cell consists of and how it works. The website has an introductory animation which is followed by more in depth description of the solid oxide fuel cell.

2012-09-12

74

Conductive oxides described  

Microsoft Academic Search

Oxides used to be thought of as insulating materials. Lately, this point of view has changed, so that any oxide containing a transition element is first suspected of being an electric conductor. Some oxides have electric conductivity equal to that of silver or copper at room temperature. Even superconductive materials are available today. Depending on the source of conductivity, conductive

H. Takagi; J. Tasaki; I. Nakagawa

1986-01-01

75

Arsenite Oxidation by a Poorly Crystalline Manganese-Oxide. 2.  

E-print Network

Arsenite Oxidation by a Poorly Crystalline Manganese-Oxide. 2. Results from X-ray Absorption September 23, 2010. Accepted October 1, 2010. Arsenite (AsIII ) oxidation by manganese oxides (Mn-oxides) servestodetoxifyand,undermanyconditions,immobilizearsenic (As) by forming arsenate (AsV ). AsIII oxidation by Mn

Sparks, Donald L.

76

Arsenite Oxidation by a Poorly Crystalline Manganese-Oxide 1.  

E-print Network

Arsenite Oxidation by a Poorly Crystalline Manganese-Oxide 1. Stirred-Flow Experiments B R A N D O September 23, 2010. Accepted October 1, 2010. Manganese-oxides (Mn-oxides) are quite reactive, with respect to arsenite (AsIII ) oxidation. However, studies regarding the pathways of AsIII oxidation, over a range

Sparks, Donald L.

77

Oxidation of aluminum nanoclusters  

SciTech Connect

The dynamics of oxidation of aluminum nanoclusters (20 nm diameter) is investigated using a parallel molecular dynamics approach based on variable charge interatomic interactions due to Streitz and Mintmire that include both ionic and covalent effects. Simulations are performed for both canonical ensembles for molecular oxygen (O{sub 2}) environments and microcanonical ensembles for molecular (O{sub 2}) and atomic (O{sub 1}) oxygen environments. Structural and dynamic correlations in the oxide region are calculated, as well as the evolution of charges, surface oxide thickness, diffusivities of atoms, and local stresses. In the microcanonical ensemble, the oxidizing reaction becomes explosive in both molecular and atomic oxygen environments due to the enormous energy release associated with Al-O bonding. Local stresses in the oxide scale cause rapid diffusion of aluminum and oxygen atoms. Analyses of the oxide scale reveal significant charge transfer and a variation of local structures from the metal-oxide interface to the oxide-environment interface. In the canonical ensemble, oxide depth grows linearly in time until {approx}30 ps, followed by saturation of oxide depth as a function of time. An amorphous oxide layer of thickness {approx}40 A is formed after 466 ps, in good agreement with experiments. The average mass density in the oxide scale is 75% of the bulk alumina density. Evolution of structural correlation in the oxide is analyzed through radial distribution and bond angles. Through detailed analyses of the trajectories of O atoms and their formation of OAl{sub n} structures, we propose a three-step process of oxidative percolation that explains deceleration of oxide growth in the canonical ensemble.

Campbell, Timothy J. [Collaboratory for Advanced Computing and Simulations, Department of Materials Science and Engineering, Department of Physics and Astronomy, Department of Computer Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Mississippi State University, Stennis Space Center, Mississippi 39529 (United States); Aral, Gurcan; Kalia, Rajiv K.; Nakano, Aiichiro; Vashishta, Priya [Collaboratory for Advanced Computing and Simulations, Department of Materials Science and Engineering, Department of Physics and Astronomy, Department of Computer Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Ogata, Shuji [Graduate School of Engineering, Nagoya Institute of Technology, Nagoya 466-8555 (Japan)

2005-05-15

78

Oxidation of propylene over copper oxide catalysts  

E-print Network

and Andrianova (65) reported that C2H4 undergoes deep oxidation to CO2 and H20 over MgO-Cr203 supported on asbestos. Studies were made using different contact times and temperatures of 287, 300 and 350o with a feed containing 26 per cent C2H4. Analog- ous... results were obtained using an asbestos supported CuO-Cr203 catalyst. Venkataramam and his co-workers (66) studied the catalytic oxidation of ethylene to ethylene oxide by the fluidized bed technique using a static bed of catalyst. Precipitated Ag20...

Billingsley, David Stuart

2012-06-07

79

Partial oxidation catalyst  

DOEpatents

A two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion. The dehydrogenation portion is a group VIII metal and the oxide-ion conducting portion is selected from a ceramic oxide crystallizing in the fluorite or perovskite structure. There is also disclosed a method of forming a hydrogen rich gas from a source of hydrocarbon fuel in which the hydrocarbon fuel contacts a two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion at a temperature not less than about 400.degree. C. for a time sufficient to generate the hydrogen rich gas while maintaining CO content less than about 5 volume percent. There is also disclosed a method of forming partially oxidized hydrocarbons from ethanes in which ethane gas contacts a two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion for a time and at a temperature sufficient to form an oxide.

Krumpelt, Michael (Naperville, IL); Ahmed, Shabbir (Bolingbrook, IL); Kumar, Romesh (Naperville, IL); Doshi, Rajiv (Downers Grove, IL)

2000-01-01

80

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

81

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

82

Oxidation-Reduction Equilibria  

NSDL National Science Digital Library

This 11-page PDF document is part of an environmental geochemistry course taught by Dr. David Sherman at the University of Bristol. Topics include oxidation-reduction reactions and oxidation states, the Nerst Equation, Eh-pH diagrams, and redox environments in nature. Also included are the calculation of Eh from concentrations and the prediction of stable oxidation states. Helpful diagrams accompany the text.

Sherman, David M.; Bristol, University O.

83

Internal oxidation during carburizing  

Microsoft Academic Search

1.Microstructural, x-ray structural, and microspectral analyses indicate that internal oxidation occurs in steels 25KhGT, 25KhGM, and 25KhGNM carburized in an endothermic atmosphere.2.The addition of 0.6% Mo to the steel does not eliminate or reduce the internal oxidation zone of chromium and manganese.3.Internal oxidation to a depth of 0.03 mm is quantitatively observed by x-ray structural analysis in all steels investigated,

V. D. Kal'ner; S. A. Yurasov

1970-01-01

84

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

85

UV Induced Oxidation of Nitric Oxide  

NASA Technical Reports Server (NTRS)

Nitric oxide in a gaseous stream is converted to nitrogen dioxide using oxidizing species generated at least in part using in situ UV radiation sources. The sources of the oxidizing species include oxygen and/or hydrogen peroxide. The oxygen may be a component of the gaseous stream or added to the gaseous stream, preferably near a UV radiation source, and is converted to ozone by the UV irradiation. The hydrogen peroxide is decomposed through a combination of vaporization and UV irradiation. The hydrogen peroxide is preferably stored at stable concentration levels, i.e., approximately 50% by volume and increased in concentration in a continuous process preceding vaporization within the flow channel of the gaseous stream and in the presence of the UV radiation sources.

Parrish, Clyde, F. (Inventor); Luecke, Dale E. (Inventor)

2007-01-01

86

Oxidants and oxidation in the Earth's atmosphere  

NASA Technical Reports Server (NTRS)

The 1994 BOC Priestley Conference was held at Bucknell University in Lewisburg, Pennsylvania, from June 24 through June 27, 1994. This conference, managed by the American Chemical Society (ACS), was a joint celebration with the Royal Society of Chemistry (RSC) commemorating Joseph Priestley's arrival in the U.S. and his discovery of oxygen. The basic theme of the conference was 'Oxidants and Oxidation in the Earth's Atmosphere,' with a keynote lecture on the history of ozone. A distinguished group of U.S. and international atmospheric chemists addressed the issues dominating current research and policy agendas. Topics crucial to the atmospheric chemistry of global change and local and regional air pollution were discussed. The program for the conference included four technical sessions on the following topics: (1) Oxidative Fate of Atmospheric Pollutants; (2) Photochemical Smog and Ozone; (3) Stratospheric Ozone; and (4) Global Tropospheric Ozone.

1995-01-01

87

Catalytic process for formaldehyde oxidation  

NASA Technical Reports Server (NTRS)

Disclosed is a process for oxidizing formaldehyde to carbon dioxide and water without the addition of energy. A mixture of formaldehyde and an oxidizing agent (e.g., ambient air containing formaldehyde) is exposed to a catalyst which includes a noble metal dispersed on a metal oxide which possesses more than one oxidation state. Especially good results are obtained when the noble metal is platinum, and the metal oxide which possesses more than one oxidation state is tin oxide. A promoter (i.e., a small amount of an oxide of a transition series metal) may be used in association with the tin oxide to provide very beneficial results.

Kielin, Erik J. (Inventor); Brown, Kenneth G. (Inventor); D'Ambrosia, Christine M. (Inventor)

1996-01-01

88

Oxidation/Reduction  

NSDL National Science Digital Library

Created by team members from Kapi'olani Community College and Leeward Community College, this site provides educators and students with a colorful background lesson in oxidation and reduction. The site is divided into concepts, exercises, and everyday examples of oxidation and reduction. Each exercise allows users to check all answers.

89

OXIDANT-PRECURSOR RELATIONSHIPS  

EPA Science Inventory

New methods of ambient air analysis were used to define more clearly the relationships between oxidants and their precursors. Non-methane hydrocarbons, NOx, O2, and oxidants were measured at the same time and location (Riverside, California). The ambient air data presented in thi...

90

Oxidative Degradation of Castanospermine  

Microsoft Academic Search

Oxidation of castanospermine (1) (HIO4) and its 6-O-acetyl derivative 7 [Pb(OAc)4], followed by reduction and acetylation, were reported. A mechanism is proposed for the novel Pb(OAc)4 oxidation of a ?-tertiary amino alcohol.

Wayne K. Anderson; Pingzhong Tan

1994-01-01

91

Solid Oxide Fuel Cells  

NSDL National Science Digital Library

This article from Gemma Crawley on solid oxide fuel cells appeared in Fuel Cell Today in January 2007. Crawley provides a technological overview of solid oxide fuel cells, information on the development of the technology and the current market for this type of fuel cell. This document may be downloaded in PDF file format.

Crawley, Gemma

2012-08-29

92

Technology Offer Oxidized Phospholipids -  

E-print Network

of plasma lipoproteins and cells that are formed in the human body under oxidative stress. Potential Fields is generated from polyunsaturated phospholipids in the human body under oxidative stress. It had been known apoptosis in cultured skin cancer cells but affect "healthy" melanocytes and keratinocytes to a much lesser

93

Oxidative stress shortens telomeres  

Microsoft Academic Search

Telomeres in most human cells shorten with each round of DNA replication, because they lack the enzyme telomerase. This is not, however, the only determinant of the rate of loss of telomeric DNA. Oxidative damage is repaired less well in telomeric DNA than elsewhere in the chromosome, and oxidative stress accelerates telomere loss, whereas antioxidants decelerate it. I suggest here

Thomas von Zglinicki

2002-01-01

94

Stabilized chromium oxide film  

DOEpatents

Stabilized air-oxidized chromium films deposited on high-power klystron ceramic windows and sleeves having a thickness between 20 and 150.ANG. are useful in lowering secondary electron emission yield and in avoiding multipactoring and window failure due to overheating. The ceramic substrate for the film is chosen from alumina, sapphire or beryllium oxide.

Garwin, Edward L. (Los Altos, CA); Nyaiesh, Ali R. (Palo Alto, CA)

1988-01-01

95

Stabilized chromium oxide film  

DOEpatents

Stabilized air-oxidized chromium films deposited on high-power klystron ceramic windows and sleeves having a thickness between 20 and 150A are useful in lowering secondary electron emission yield and in avoiding multipactoring and window failure due to overheating. The ceramic substrate for the film is chosen from alumina, sapphire or beryllium oxide.

Nyaiesh, A.R.; Garwin, E.L.

1986-08-04

96

Oxidizing enzymes as biocatalysts  

Microsoft Academic Search

This article describes oxidising enzymes used for biocatalytic applications. Redox biocatalysts are highly sought after because of the selectivity, controllability and economy of their reactions, in comparison with conventional chemical reactions. Increasing numbers of oxidative biotransformations are being reported, indicating wide variability in the biocatalyst characteristics and a range of potential and established applications. Several limitations apply to oxidative biotransformations,

Stephanie G. Burton

2003-01-01

97

On dissolved phosphorus in the Gulf of Mexico  

E-print Network

of Ketchum, Corwin and Keen (1955). Release of P from organic P compounds may be accom- plished by either acid hydrolysis w1th perchloric acid (Strickland and Parsons, 1965) or ox1dation with potas- sium persulfate (Menzel and Corwin, 1965). The former... has the advantage of eliminating arsenate interference while the latter is adaptable to shipboard determina- tions. Persulfate oxidation has been shown to be as effective as other digestion techniques (Menzel and Corwin, 1965). No rapid and direct...

Wright, David John

2012-06-07

98

Oxidation characteristics of molybdenum-zirconium oxide cermets  

NASA Technical Reports Server (NTRS)

The oxidation of molybdenum is affected by the factors of temperature, the oxygen pressure in the oxidizing atmosphere, and the time of exposure. Studies of the oxidation characteristics of Mo show that the oxidation rate increases strongly when the temperature exceeds 600 C. Investigations of the behavior of cermets with various percentages of zirconium oxide are discussed, taking into account oxidation conditions at temperatures under and above the melting point of molybdenum trioxide.

Heitzinger, B.

1984-01-01

99

Nitric Oxide Nanoparticle Technology  

PubMed Central

Staphylococcus aureus infections account for the majority of skin and soft tissue infections in the United States. Staphylococcus aureus is rapidly evolving resistance to contemporary topical as well as systemic antibiotics. Alternatives to current treatment options for skin and soft tissue infections are needed for more effective treatment now and in the future. Nitric oxide's proven roles in both wound repair and as an antimicrobial agent make it an excellent candidate for the treatment of skin infections. Recent attempts at novel nitric oxide therapies, in the form of nitric oxide donors, have shown limited potential in treating cutaneous infection. However, more recent developments in nitric oxide delivery, using nitric oxide nanoparticle technology, demonstrate substantial promise in the promotion of wound repair and eradication of skin and soft tissue infections. PMID:20725551

Englander, Laura

2010-01-01

100

Catastrophic oxidation of metals  

NASA Astrophysics Data System (ADS)

The review deals with the current state of the problem of catastrophic oxidation of metals ('hot corrosion') caused by formation of a liquid corrosion product in a multi-component system. The kinetics, thermodynamics, and mechanisms of the two stages of accelerated oxidation of metals, namely, fast and super-fast stages, are considered with the copper-bismuth oxide system as an example. It is shown that the fast stage is caused by the formation of a liquid-channel grain boundary structure in the corrosion product, while the super-fast stage is caused by the high rate of dissolution of the oxide layer. The results of studies of the interaction of liquid phase with two-dimensional defects (grain boundaries) in solids are generalised. A model of catastrophic oxidation of metals is proposed. The bibliography includes 104 references.

Belousov, Valerii V.

1998-07-01

101

Exploiting Covalency to Enhance MetalOxide and OxideOxide Adhesion at Heterogeneous Interfaces  

E-print Network

provide some means of oxidation/ corrosion protection for the superalloy. This goal partially moti- vatesExploiting Covalency to Enhance Metal­Oxide and Oxide­Oxide Adhesion at Heterogeneous Interfaces to those formed using more ionic oxides, such as Al2O3, in place of SiO2. The improved strength

Carter, Emily A.

102

Boric oxide deposition on carbon nanofibers for oxidation resistance.  

PubMed

The boric oxide deposition was performed to improve the oxidation resistivity of carbon nanofiber (CNF) from electrospinning at elevated temperatures. The stabilized electrospun polyacrylonitrile (PAN) nanofibers were coated with boric oxide, followed by heat treatment up to 1000, 1200, and 1400 degrees C in an inert nitrogen atmosphere. The relative oxidation resistance of boric oxide-coated CNFs showed oxidation resistive property, which was determined by weight loss after running a thermogravimetric analyzer (TGA) under air flow. The data were used for the calculations of activation energies through Arrhenius plot. The oxidation resistance of the boric oxide-coated CNFs was depended on the heat treatment temperature, the higher the temperature more resistive to oxidation. The boric oxide-coated CNFs showed extended oxidation resistivity as remaining 40-83% (w) of the original weight at the high temperature 1000 degrees C under air. PMID:23882810

Chae, Hyang Hoon; Kim, Bo-Hye; Yang, Kap Seung; Woo, Hee-Gweon

2013-08-01

103

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

104

Ethylene Oxide Gaseous Sterilization  

PubMed Central

The relationships of reaction temperature and concentration of gaseous ethylene oxide to the time required for inactivation of air-dried Bacillus subtilis var. niger spores are more complex than previously reported. A plot of temperature vs. the logarithm of “thermochemical death time” (TCDT) resulted in a straight line between 18 and 57 C for systems of “high” ethylene oxide concentration. The TCDT values were independent of ethylene oxide concentrations above certain temperature-dependent limits. A given ethylene oxide concentration produced a TCDT curve identical in the upper temperature regions with that for higher concentrations. As the temperature was lowered beyond a critical point, this curve diverged from that for higher concentrations, as a straight line of lesser slope. Thus, a series of curves exists for a range of ethylene oxide concentrations. They are characterized by two segments, both logarithmic, intersecting at a critical temperature for each concentration. The intersecting point is at a temperature inversely related to the ethylene oxide gas concentration. The temperature quotient for the high temperature segments of all systems was 1.8. This value was characteristic for ethylene oxide concentrations of 440 and 880 mg/liter at temperatures above 40.6 and 33.4 C, respectively. Below these critical temperatures, the Q10 values for the respective systems were 3.2 and 2.3. PMID:13890659

Ernst, Robert R.; Shull, James J.

1962-01-01

105

Biologically inspired oxidation catalysis.  

PubMed

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 for aerobic oxidations. Important inroads have been made in applying this knowledge to the development of synthetic catalysts that model enzyme function. Such biologically inspired hydrocarbon oxidation catalysts hold great promise for wide-ranging synthetic applications. PMID:18800132

Que, Lawrence; Tolman, William B

2008-09-18

106

Mercuric oxide poisoning  

MedlinePLUS

Mercuric oxide may be found in some: Button batteries (batteries containing mercury are no longer sold in the ... stomach ( gastric lavage ) Any person who swallowed a battery will need immediate x-rays to make sure ...

107

Oxidative Stress in Asthma  

PubMed Central

Abstract Asthma is a chronic inflammatory lung disease that results in airflow limitation, hyperreactivity, and airway remodeling. There is strong evidence that an imbalance between the reducing and oxidizing systems favoring a more oxidative state is present in asthma. Endogenous and exogenous reactive oxygen species, such as superoxide anion, hydroxyl radical, hypohalite radical, and hydrogen peroxide, and reactive nitrogen species, such as nitric oxide, peroxynitrite, and nitrite, play a major role in the airway inflammation and are determinants of asthma severity. Asthma is also associated with decreased antioxidant defenses, such as superoxide dismutase, catalase, and glutathione. In this review, we will summarize the current knowledge and discuss the current and future strategies for the modulation of oxidative stress in asthma. PMID:23268432

Sahiner, Umit M; Birben, Esra; Erzurum, Serpil; Sackesen, Cansin

2011-01-01

108

Nitric oxide neurotoxicity  

Microsoft Academic Search

Derangements in glutamate neurotransmission have been implicated in several neurodegenerative disorders including, stroke, epilepsy, Huntington's disease, Alzheimer's disease, and amyotrophic lateral sclerosis (ALS). Activation of the N-methyl-d-aspartate (NMDA) receptor subtype of glutamate receptors results in the influx of calcium which binds calmodulin and activates neuronal nitric oxide synthase (nNOS), to convent l-arginine to citrulline and nitric oxide (NO). NO has

Valina L. Dawson; Ted M. Dawson

1996-01-01

109

Study of coal oxidation  

Microsoft Academic Search

Three coals were oxidized in a fluidized bed, using air at temperatures from 175°C to 280°C and total pressures from 126 kPa. to 274 kPa., for periods of up to 24 hours. An infrared analyzer was used to measure concentrations of carbon oxide gases in the fluidizing stream. Both CO and COâ rates declined with time and increased with total

Kalema

1985-01-01

110

CCMR: Cobalt Oxide Nanocubes  

NSDL National Science Digital Library

This research studies and conduct tests on cobalt oxide nanocubes, a nanoparticle that will be used in several applications. Silica nanoparticles are round shape while cobalt oxide nanocubes are cubic shaped making them a better option. Shear Thickening Fluid testing has indicated that the technology allows conventional ballistic fabrics to amplify the level and quality of protection they provide without compromising weight, comfort or flexibility.

Lee, Sabrina R.

2009-08-15

111

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

112

Nitrous oxide in oxidation chemistry and catalysis: application and production  

Microsoft Academic Search

An overview is given on extensive studies, which are targeted to involve N2O into organic synthesis as an oxidant. Due to unique oxidative properties, nitrous oxide provides remarkable prospects in catalytic and non-catalytic oxidation chemistry in both gas and liquid phases. The interest to new oxidant resulted in appearance of a new technology for the production of inexpensive N2O too.

V. N. Parmon; G. I. Panov; A. Uriarte; A. S. Noskov

2005-01-01

113

Staphylococcal response to oxidative stress  

PubMed Central

Staphylococci are a versatile genus of bacteria that are capable of causing acute and chronic infections in diverse host species. The success of staphylococci as pathogens is due in part to their ability to mitigate endogenous and exogenous oxidative and nitrosative stress. Endogenous oxidative stress is a consequence of life in an aerobic environment; whereas, exogenous oxidative and nitrosative stress are often due to the bacteria's interaction with host immune systems. To overcome the deleterious effects of oxidative and nitrosative stress, staphylococci have evolved protection, detoxification, and repair mechanisms that are controlled by a network of regulators. In this review, we summarize the cellular targets of oxidative stress, the mechanisms by which staphylococci sense oxidative stress and damage, oxidative stress protection and repair mechanisms, and regulation of the oxidative stress response. When possible, special attention is given to how the oxidative stress defense mechanisms help staphylococci control oxidative stress in the host. PMID:22919625

Gaupp, Rosmarie; Ledala, Nagender; Somerville, Greg A.

2012-01-01

114

Enargite oxidation: A review  

NASA Astrophysics Data System (ADS)

Enargite, Cu 3AsS 4, is common in some deposit types, e.g. porphyry systems and high sulphidation epithermal deposits. It is of environmental concern as a potential source of arsenic. In this communication, we review the current knowledge of enargite oxidation, based on the existing literature and our own original data. Explicit descriptions of enargite oxidation in natural environments are scarce. The most common oxidized alteration mineral of enargite is probably scorodite, FeAsO 4.2H 2O, with iron provided most likely by pyrite, a phase almost ubiquitously associated with enargite. Other secondary minerals after enargite include arsenates such as chenevixite, Cu 2Fe 2(AsO 4) 2(OH) 4.H 2O, and ceruleite, Cu 2Al 7(AsO 4) 4.11.5H 2O, and sulphates such as brochantite, Cu 4(SO 4)(OH) 6, and posnjakite, Cu 4(SO 4)(OH) 6·H 2O. Detailed studies of enargite field alteration at Furtei, Sardinia, suggest that most alteration occurs through dissolution, as testified by the appearance of etch pits at the surface of enargite crystals. However, apparent replacement by scorodite and cuprian melanterite was observed. Bulk oxidation of enargite in air is a very slow process. However, X-ray photoelectron spectroscopy (XPS) reveals subtle surface changes. From synchrotron-based XPS it was suggested that surface As atoms react very fast, presumably by forming bonds with oxygen. Conventional XPS shows the formation, on aged samples, of a nanometer-size alteration layer with an appreciably distinct composition with respect to the bulk. Mechanical activation considerably increases enargite reactivity. In laboratory experiments at acidic to neutral pH, enargite oxidation/dissolution is slow, although it is accelerated by the presence of ferric iron and/or bacteria such as Acidithiobacillus ferrooxidans and Sulfolobus BC. In the presence of sulphuric acid and ferric iron, the reaction involves dissolution of Cu and formation of native sulphur, subsequently partly oxidized to sulphate. At alkaline pH, the reactivity of enargite is apparently slightly greater. XPS spectra of surfaces conditioned at pH 11 have been interpreted as evidence of formation of a number of surface species, including cupric oxide and arsenic oxide. Treatment with hypochlorite solutions at pH 12.5 quickly produces a coating of cupric oxide. Electrochemical oxidation of enargite typically involves low current densities, confirming that the oxidation process is slow. Important surface changes occur only at high applied potentials, e.g. + 0.74 V vs. SHE. It is confirmed that, at acidic pH, the dominant process is Cu dissolution, accompanied (at + 0.56 V vs. SHE, pH = 1) by formation of native sulphur. At alkaline pH, a number of surface products have been suggested, including copper and arsenic oxides, and copper arsenates. XPS studies of the reacted surfaces demonstrate the evolution of Cu from the monovalent to the divalent state, the formation of As-O bonds, and the oxidation of sulphur to polysulphide, sulphite and eventually sulphate. In most natural and quasi-natural (mining) situations, it is expected that enargite reactivity will be slow. Moreover, it is likely that the release of arsenic will be further slowed down by at least temporary trapping in secondary phases. Therefore, an adequate management of exposed surfaces and wastes should minimize the environmental impact of enargite-bearing deposits. In spite of an increasing body of data, there are several gaps in our knowledge of enargite oxidation. The exact nature of most mechanisms and products remains poorly constrained, and there is a lack of quantitative data on the dependence on parameters such as pH and dissolved oxygen.

Lattanzi, Pierfranco; Da Pelo, Stefania; Musu, Elodia; Atzei, Davide; Elsener, Bernhard; Fantauzzi, Marzia; Rossi, Antonella

2008-01-01

115

Metal oxide-polymer composites  

NASA Technical Reports Server (NTRS)

A method of making metal oxide clusters in a single stage by reacting a metal oxide with a substoichiometric amount of an acid in the presence of an oxide particle growth terminator and solubilizer. A method of making a ceramer is also disclosed in which the metal oxide clusters are reacted with a functionalized polymer. The resultant metal oxide clusters and ceramers are also disclosed.

Wellinghoff, Stephen T. (Inventor)

1997-01-01

116

Metal oxide-polymer composites  

NASA Technical Reports Server (NTRS)

A method of making metal oxide clusters in a single stage by reacting a metal oxide with a substoichiometric amount of an acid in the presence of an oxide particle growth terminator and solubilizer. A method of making a ceramer is also disclosed in which the metal oxide clusters are reacted with a functionalized polymer. The resultant metal oxide clusters and ceramers are also disclosed.

Wellinghoff, Stephen T. (Inventor)

1994-01-01

117

Structure of tungsten oxide nanoclusters  

Microsoft Academic Search

Tungsten oxide clusters were prepared by oxidizing tungsten clusters deposited on sapphire. The oxidation was carried out by thermal treatment under various conditions. The morphology and the structure of the oxide clusters were investigated by AFM and RHEED. It was found that the tungsten deposit on the Al2O3 substrate was partially oxidized to WO2 by annealing in vacuum. The Al2O3

M. Gillet; K. Masek; E. Gillet

2004-01-01

118

Stabilized tin-oxide-based oxidation/reduction catalysts  

NASA Technical Reports Server (NTRS)

The invention described herein involves a novel approach to the production of oxidation/reduction catalytic systems. The present invention serves to stabilize the tin oxide reducible metal-oxide coating by co-incorporating at least another metal-oxide species, such as zirconium. In one embodiment, a third metal-oxide species is incorporated, selected from the group consisting of cerium, lanthanum, hafnium, and ruthenium. The incorporation of the additional metal oxide components serves to stabilize the active tin-oxide layer in the catalytic process during high-temperature operation in a reducing environment (e.g., automobile exhaust). Moreover, the additional metal oxides are active components due to their oxygen-retention capabilities. Together, these features provide a mechanism to extend the range of operation of the tin-oxide-based catalyst system for automotive applications, while maintaining the existing advantages.

Jordan, Jeffrey D. (Inventor); Schryer, David R. (Inventor); Davis, Patricia P. (Inventor); Leighty, Bradley D. (Inventor); Watkins, Anthony Neal (Inventor); Schryer, Jacqueline L. (Inventor); Oglesby, Donald M. (Inventor); Gulati, Suresh T. (Inventor); Summers, Jerry C. (Inventor)

2008-01-01

119

Bacteriogenic manganese oxides.  

PubMed

Microorganisms control the redox cycling of manganese in the natural environment. Although the homogeneous oxidation of Mn(II) to form manganese oxide minerals is slow, solid MnO(2) is the stable form of manganese in the oxygenated portion of the biosphere. Diverse bacteria and fungi have evolved the ability to catalyze this process, producing the manganese oxides found in soils and sediments. Other bacteria have evolved to utilize MnO(2) as a terminal electron acceptor in respiration. This Account summarizes the properties of Mn oxides produced by bacteria (bacteriogenic MnO(2)) and our current thinking about the biochemical mechanisms of bacterial Mn(II) oxidation. According to X-ray absorption spectroscopy and X-ray scattering studies, the MnO(2) produced by bacteria consists of stacked hexagonal sheets of MnO(6) octahedra, but these particles are extremely small and have numerous structural defects, particularly cation vacancies. The defects provide coordination sites for binding exogenous metal ions, which can be adsorbed to a high loading. As a result, bacterial production of MnO(2) influences the bioavailability of these metals in the natural environment. Because of its high surface area and oxidizing power, bacteriogenic MnO(2) efficiently degrades biologically recalcitrant organic molecules to lower-molecular-mass compounds, spurring interest in using these properties in the bioremediation of xenobiotic organic compounds. Finally, bacteriogenic MnO(2) is reduced to soluble Mn(II) rapidly in the presence of exogenous ligands or sunlight. It can therefore help to regulate the bioavailability of Mn(II), which is known to protect organisms from superoxide radicals and is required to assemble the water-splitting complex in photosynthetic organisms. Bioinorganic chemists and microbiologists have long been interested in the biochemical mechanism of Mn(IV) oxide production. The reaction requires a two-electron oxidation of Mn(II), but genetic and biochemical evidence for several bacteria implicate multicopper oxidases (MCOs), which are only known to engage one-electron transfers from substrate to O(2). In experiments with the exosporium of a Mn(II)-oxidizing Bacillus species, we could trap the one-electron oxidation product, Mn(III), as a pyrophosphate complex in an oxygen-dependent reaction inhibited by azide, consistent with MCO catalysis. The Mn(III) pyrophosphate complex can further act as a substrate, reacting in the presence of the exosporium to produce Mn(IV) oxide. Although this process appears to be unprecedented in biology, it is reminiscent of the oxidation of Fe(II) to form Fe(2)O(3) in the ferritin iron storage protein. However, it includes a critical additional step of Mn(III) oxidation or disproportionation. We shall continue to investigate this biochemically unique process with purified enzymes. PMID:19778036

Spiro, Thomas G; Bargar, John R; Sposito, Garrison; Tebo, Bradley M

2010-01-19

120

Switching Oxide Traps  

NASA Technical Reports Server (NTRS)

We consider radiation-induced charge trapping in SiO2 dielectric layers, primarily from the point of view of CMOS devices. However, SiO2 insulators are used in many other ways, and the same defects occur in other contexts. The key studies, which determined the nature of the oxide charge traps, were done primarily on gate oxides in CMOS devices, because that was the main radiation problem in CMOS at one time. There are two major reviews of radiation-induced oxide charge trapping already in the literature, which discuss the subject in far greater detail than is possible here. The first of these was by McLean et al. in 1989, and the second, ten years later, was intended as an update, because of additional, new work that had been reported. Basically, the picture that has emerged is that ionizing radiation creates electron-hole pairs in the oxide, and the electrons have much higher mobility than the holes. Therefore, the electrons are swept out of the oxide very rapidly by any field that is present, leaving behind any holes that escape the initial recombination process. These holes then undergo a polaron hopping transport toward the Si/SiO2 interface (under positive bias). Near the interface, some fraction of them fall into deep, relatively stable, long-lived hole traps. The nature and annealing behavior of these hole traps is the main focus of this paper.

Oldham, Timothy R.

2003-01-01

121

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

122

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

123

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

124

Ethylene Oxide Gaseous Sterilization  

PubMed Central

The duration of the equilibration period between admission of water vapor and subsequent introduction of gaseous ethylene oxide to an evacuated sterilizer chamber was studied with respect to its effect on the inactivation of spores of Bacillus subtilis var. niger under simulated practical conditions. Introduction of a water-adsorbing cotton barrier between the spores and an incoming gas mixture of water vapor and ethylene oxide caused a marked increase in the observed thermochemical death time of the spore populations. This effect was negated by admission of water vapor one or more minutes prior to introduction of ethylene oxide gas. Increases in temperature and relative humidity of the system promoted passage of water vapor through the cotton barriers and diminished their effect. PMID:13890660

Ernst, Robert R.; Shull, James J.

1962-01-01

125

[Nitric oxide metabolism].  

PubMed

Nitric oxide is an important mediator of physiological and pathological processes. It is a lipophilic molecule that contains a single unpaired electron which causes NO to be chemically reactive, and to function as a free radical with a short lifetime. NO can act by direct and indirect effects. Direct effects occur between NO and specific biological molecules whereas indirect effects are mediated by reactive nitrogen oxide species (RNOS) formed from the reaction of NO either with oxygen or superoxide. This review discusses the metabolic pathways of NO. PMID:17427511

Kowalczyk, Edward; Kopff, Anna; Kopff, Maria; B?aszczyk, Jan; Fija?kowski, Pawe?; Kowalski, Jan

2006-01-01

126

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

127

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

128

Low temperature oxidation of plutonium  

SciTech Connect

The initial oxidation of gallium stabilized {delta}-plutonium metal at 193 K has been followed using x-ray photoelectron spectroscopy. On exposure to Langmuir quantities of oxygen, plutonium rapidly forms a trivalent oxide followed by a tetravalent plutonium oxide. The growth modes of both oxides have been determined. Warming the sample in vacuum, the tetravalent oxide reduces to the trivalent oxide. The kinetics of this reduction reaction have followed and the activation energy has been determined to be 38.8 kJ mol{sup -1}.

Nelson, Art J. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Roussel, Paul [AWE, Aldermaston, Reading, Berkshire, RG7 4PR (United Kingdom)

2013-05-15

129

Uranium oxidation: characterization of oxides formed by reaction with water  

SciTech Connect

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 at the oxide/metal interface. Single laminae are released if liquid water is present due to the prizing penetration at the reaction zone. The rate of reaction of water with uranium is directly proportional to the amount of adsorbed water on the oxide product. Rapid transport is effected through the open hydrous oxide product. Dehydration of the hydrous oxide irreversibly forms a more inert oxide which cannot be rehydrated to the degree that prevails in the original hydrous product of uranium oxidation with water. 27 figures.

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

1983-04-27

130

High-Performance Manganese Oxide Catalysts for CO Oxidation  

Microsoft Academic Search

The catalytic activity of manganese dioxide samples in oxidation of CO and decomposition of hydrogen peroxide was studied. The promise of manganese dioxide obtained from fluorine-containing electrolytes as a catalyst for carbon monoxide oxidation was considered.

N. D. Ivanova; S. V. Ivanov; E. I. Boldyrev; G. V. Sokol'skii; I. S. Makeeva

2002-01-01

131

Diesel engine exhaust oxidizer  

SciTech Connect

This patent describes a diesel engine exhaust oxidizing device. It comprises: an enclosure having an inlet for receiving diesel engine exhaust, a main flow path through the enclosure to an outlet of the enclosure, a by-ass through the enclosure, and a microprocessor control means.

Kammel, R.A.

1992-06-16

132

Solid Oxide Fuel Cells  

NSDL National Science Digital Library

This reference sheet provides some basic information on solid oxide fuel cells. This document includes information on the basic operation of these fuel cells and some useful graphics. This document would probably be more useful for students who already have a basic understanding of fuel cells.This document may be downloaded in PDF file format.

2012-07-20

133

Imaging gate oxide ruptures  

Microsoft Academic Search

As minimum feature sizes are reduced in MOS silicon devices, dielectric breakdown continues to pose a formidable challenge. A more complete understanding of the failure mechanism which induces oxide rupture has become an absolute necessity in order to meet the advancing yield and reliability requirements of today's complex integrated structures. This paper will present an interesting insight into the nature

Horacio Mendez; Steve Morris; Sudhindra Tatti; Nicholas Dickson; Ronald E. Pyle

1993-01-01

134

Oxidation of Cellulose  

Microsoft Academic Search

Oxidation ageing experiments on paper and transformer oil insulation has been performed using two different techniques. First, we used oxygen pressurized bottles with oil-paper isolation where oil and paper are sampled at certain intervals during 8 months and degree of polymerization is measured. Second, a microcalorimeter measuring continuously the heat flow from the paper-oil sample was used. We find that

K. B. Liland; M. H. Ese; L. Lundgaard; M. Kes

2008-01-01

135

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

136

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

137

Highly oxidized superconductors  

DOEpatents

Novel superconducting materials in the form of compounds, structures or phases are formed by performing otherwise known synthesis 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. 16 figs.

Morris, D.E.

1994-09-20

138

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

139

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...

140

Oxidation behavior of superalloys in oxidizing and reducing environments  

Microsoft Academic Search

Superalloys Inconel 718 and Inconel 625 were exposed for 3000 h to various corrosive oxidizing and reducing environments typically found in carbonate fuel cells. The corroded specimens were characterized in terms of their corrosion scale morphology, composition, and phases. The alloys have excellent oxidation resistance and scale adherence in the oxidizing cathode environment. A mechanism governing the formation of the

Li Jian; C. Y. Yuh; M. Farooque

2000-01-01

141

High-yield electro-oxidative preparation of graphene oxide.  

PubMed

Herein, we report a green electrochemical oxidative approach to convert large quantities of graphite into graphene oxide (GO). The resulted GO flakes have been characterized using various analytical techniques. It was possible to control the degree of oxidation of the produced GO via controlling the electrochemical parameters of the process. PMID:24948081

Abdelkader, A M; Kinloch, I A; Dryfe, R A W

2014-08-01

142

Oxidative Reforming of Biodiesel Over Molybdenum (IV) Oxide  

E-print Network

Oxidative Reforming of Biodiesel Over Molybdenum (IV) Oxide Jessica Whalen, Oscar Marin Flores, Su University INTRODUCTION Energy consumption continues to skyrocket worldwide. Biodiesel is a renewable fuel as potential feedstock in solid oxide fuel cells. Petroleum based fuels become scarcer daily, and biodiesel

Collins, Gary S.

143

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

144

Oxidative Stress and Psychological Disorders  

PubMed Central

Oxidative stress is an imbalance between cellular production of reactive oxygen species and the counteracting antioxidant mechanisms. The brain with its high oxygen consumption and a lipid-rich environment is considered highly susceptible to oxidative stress or redox imbalances. Therefore, the fact that oxidative stress is implicated in several mental disorders including depression, anxiety disorders, schizophrenia and bipolar disorder, is not surprising. Although several elegant studies have established a link between oxidative stress and psychiatric disorders, the causal relationship between oxidative stress and psychiatric diseases is not fully determined. Another critical aspect that needs much attention and effort is our understanding of the association between cellular oxidative stress and emotional stress. This review examines some of the recent discoveries that link oxidative status with anxiety, depression, schizophrenia and bipolar disorder. A discussion of published results and questions that currently exist in the field regarding a causal relationship between oxidative and emotional stress is also provided. PMID:24669208

Salim, Samina

2014-01-01

145

Experiments with Unusual Oxidation States  

ERIC Educational Resources Information Center

Describes four synthesis experiments, adapted for the general chemistry laboratory, in which compounds in unusual oxidation are prepared. The abnormal oxidation states involved in the synthesis products are: silver (II), chromium (II), lead (IV), and bromine (I). (MLH)

Kauffman, G. B.

1975-01-01

146

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. PMID:19715356

Hambly, David M.; Gross, Michael L.

2010-01-01

147

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

148

Magnetic properties of graphite oxide and reduced graphene oxide  

NASA Astrophysics Data System (ADS)

Graphite oxide (GO) and reduced graphene oxide (RGO) have been prepared using standard chemical methods. The formations of the oxides are characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) studies. Both the oxides exhibit weak superparamagnetism and hysteresis for the first time at room temperature. Magnetic moment for RGO is comparatively smaller than that of GO sample. The superparamagnetism in these oxides is attributed to the presence of single domains, each domain being cluster of defect induced magnetic moments coupled by ferromagnetic interaction. Apart from these single domain clusters there are other defect induced moments coupled by ferromagnetic interaction which show ferromagnetism and hysteresis.

Sarkar, S. K.; Raul, K. K.; Pradhan, S. S.; Basu, S.; Nayak, A.

2014-11-01

149

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

150

Metal oxide-based transparent conducting oxides  

NASA Astrophysics Data System (ADS)

Transparent conducting oxides (TCOs) are important materials widely used for transparent contacts in flat panel displays, light emitting diodes, and solar cells. While Sn-doped In2O3 (ITO) continues to be the TCO of choice, the increasing cost of raw In has resulted in an increasing interest in developing In-free alternatives to ITO. In this work, two metal oxide systems were investigated for their viability as In-free TCO materials. First, Nb- or Ta-doped anatase TiO2 was selected due to the recent reports of high conductivity in pulse laser deposited (PLD) films. Thin films doped with either 15 mol% Nb or 20 mol% Ta were deposited on glass and SrTiO3 (STO) substrates using RF magnetron sputtering techniques. In all cases, maximum conductivity was achieved when the films crystallized in the anatase structure of TiO2. Films sputtered on STO possessed similar electrical and optical properties as PLD films on STO, yet at a much lower deposition temperature while films deposited on glass had much lower conductivity, due to dramatically reduced mobility. Two-dimensional x-ray diffraction analysis showed that doped TiO2 films sputter deposited on STO were biaxially textured along the (004) direction. This texturing was not observed in films deposited on glass, which were composed of randomly-oriented crystalline anatase. Biaxial texturing in the film helps to reduce grain boundary resistance, thereby increasing carrier mobility and further enhancing conductivity. The Cu-based delafossite system (CuBO2, B is a 3+ metal cation) was selected as the second TCO material system due to its natural p-type conductivity, a rarity among existing TCOs. Study of this system was two-pronged: (1) application of codoping techniques to achieve bipolar conductivity; and (2) investigate stability of mixed B cation delafossites. CuAlO2 and CuGaO2 were both codoped with varying ratios of donors and acceptors in an attempt to achieve bipolar conductivity. Very little change in the electrical properties of the two materials was observed. Synthesis of multiple mixed B cation delafossite compositions was attempted. Through the course of investigation, it was determined that stability of the delafossite phase is likely controlled by the electrical properties of the metal cations.

Gillispie, Meagen Anne

151

Oxides Heterostructures for Nanoelectronics  

SciTech Connect

We summarise in this paper the work of two groups focusing on the synthesis and characterisation of functional oxide for nanoelectronic applications. In the first section, we discuss the growth by liquid-injection MOCVD of oxides heterostructures. Interface engineering for the minimisation of silicate formation during the growth of polycrystalline SrTiO{sub 3} on Si is first presented. It is realised via the change of reactant flow or chemical nature at the Si surface. We then report on the epitaxy on oxide substrates of manganites films and superlattices and on their magnetic and electrical properties. La{sub 0.7}Sr{sub 0.3}MnO{sub 3} and La{sub 0.8}MnO{sub 3-{delta}} as well as multiferroic hexagonal ReMnO{sub 3} manganites are considered. We show that the film thickness and related strain may be used to tune the properties. Finally, we demonstrate the growth of MgO nanowires by CVD at a moderate temperature of 600 C, using gold as a catalyst. In the second section, we discuss the growth of epitaxial oxide heterostructures by MBE. First, the direct epitaxy of SrTiO{sub 3} on Si is considered. Issues and control of the SrTiO{sub 3}/Si interface are discussed. An abrupt interface is achieved. We show that SrTiO{sub 3} on Si can be used as a buffer layer for the epitaxy of various perovskite oxides such as LaAlO{sub 3} or La{sub 0.7}Sr0.3MnO{sub 3}. La{sub 0.7}Sr{sub 0.3}MnO{sub 3} films are ferromagnetic and metallic at room temperature. The epitaxial growth of complex oxides on Si wafers opens up the route to the integration of a wide variety of functionalities in nanoelectronics. Finally, we discuss the monolithic integration of III-V compounds such as InP on Si using epitaxial SrTiO{sub 3} buffer layers for the future integration of optics on Si.

C Dubourdieu; I Gelard; O Salicio; G Saint-Girons; B Vilquin; G Hollinger

2011-12-31

152

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

153

Tetragonal hafnium oxide film prepared by low-temperature oxidation  

NASA Astrophysics Data System (ADS)

We used pulse-mode rapid thermal annealing to reoxidize a sputter-deposited hafnium oxide film. This reoxidation enabled the densification of the processed film, and low-temperature tetragonal hafnium oxide was obtained. When a hafnium oxide/silicon structure was subjected to the proposed process, some oxygen atoms were formed by hafnium oxide, which then react with silicon. A thin hafnium silicate layer was formed between reoxidized hafnium oxide and silicon, which was beneficial for improving the interfacial condition of hafnium oxide and silicon. The obtained low-temperature tetragonal hafnium oxide film had a high dielectric constant of 23 and a high dielectric strength of 12.7 MV/cm.

Lin, Chiung-Wei; Chiang, Yi-Tsung

2014-11-01

154

ORIGINAL ARTICLE Sulfur oxidizers dominate carbon fixation  

E-print Network

ORIGINAL ARTICLE Sulfur oxidizers dominate carbon fixation at a biogeochemical hot spot in the dark clade of marine gamma-proteobacterial sulfur oxidizers (GSOs) are distributed throughout proteins for sulfur oxidation (adenosine phosphosulfate reductase, sox (sulfur oxidizing system

Hansell, Dennis

155

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

156

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

157

Exhaled nitric oxide.  

PubMed

Exhaled nitric oxide (FENO) is a noninvasive easily measurable biomarker that is proving to be an excellent surrogate for eosinophilic inflammation in the lungs of patients who have asthma. Although large-scale normative data are still awaited, preliminary studies have shown FENO to be helpful in diagnosing and assessing severity and control for asthma. FENO levels have also proven helpful in diagnosing and managing several other inflammatory lung diseases. PMID:17996576

Stewart, Lora; Katial, Rohit

2007-11-01

158

Oxidative Metabolism in Muscle  

Microsoft Academic Search

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

M. Ferrari; T. Binzoni; V. Quaresima

1997-01-01

159

Nitric Oxide for Children  

Microsoft Academic Search

\\u000a The introduction of inhaled nitric oxide (iNO) for the treatment of hypoxemic respiratory failure in neonates ushered in a\\u000a new era in neonatal intensive care. This inhalational therapeutic redefined the medical management of the infant with persistent\\u000a pulmonary hypertension of the newborn (PPHN). With a selective pulmonary vasodilator in hand, a kinder, gentler approach to\\u000a ventilation was embraced in many

Judy L. Aschner; Candice D. Fike; Eric Austin; J. Donald Moore; Frederick E. Barr

160

Arsenopyrite oxidation – A review  

Microsoft Academic Search

Arsenopyrite (FeAsS) is the most common As-bearing sulfide mineral. Under oxidising conditions, such as those in mine waste systems, it breaks down to release acids of As and S into the environment, resulting in acid mine drainage with high concentrations of dissolved As. In this communication, current knowledge of arsenopyrite oxidation is reviewed based on a survey of the existing

C. L. Corkhill; D. J. Vaughan

2009-01-01

161

Ultra supercritical steamside oxidation  

SciTech Connect

Ultra supercritical (USC) power plants offer the promise of higher efficiencies and lower emissions, Current goals of the U.S. Department of Energy’s Advanced Power Systems Initiatives include coal generation at 60% efficiency, which would 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.

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

2005-01-01

162

The role of oxidative debris on graphene oxide films.  

PubMed

We study the effect of oxidative impurities on the properties of graphene oxide and on the graphene oxide Langmuir-Blodgett films (LB). The starting material was grupo Antolín nanofibers (GANF) and the oxidation process was a modified Hummers method to obtain highly oxidized graphene oxide. The purification procedure reported in this work eliminated oxidative impurities decreasing the thickness of the nanoplatelets. The purified material thus obtained presents an oxidation degree similar to that achieved by chemical reduction of the graphite oxide. The purified and non-purified graphene oxides were deposited onto silicon by means of a Langmuir-Blodgett (LB) methodology. The morphology of the LB films was analyzed by field emission scanning microscopy (FE-SEM) and micro-Raman spectroscopy. Our results show that the LB films built by transferring Langmuir monolayers at the liquid-expanded state of the purified material are constituted by close-packed and non-overlapped nanoplatelets. The isotherms of the Langmuir monolayer precursor of the LB films were interpreted according to the Volmer's model. PMID:24166869

López-Díaz, David; Velázquez, Maria Mercedes; Blanco de La Torre, Santiago; Pérez-Pisonero, Ana; Trujillano, Raquel; García Fierro, José Luis; Claramunt, Sergi; Cirera, Albert

2013-12-01

163

Solid Oxide Fuel Cells  

SciTech Connect

Solid oxide fuel cell (SOFC) technology, which offers many advantages over traditional energy conversion systems including low emission and high efficiency, has become increasingly attractive to the utility, automotive, and defense industries (as shown in Figure 1). As an all solid-state energy conversion device, the SOFC operates at high temperatures (700-1,000 C) and produces electricity by electrochemically combining the fuel and oxidant gases across an ionically conducting oxide membrane. To build up a useful voltage, a number of cells or PENs (Positive cathode-Electrolyte-Negative anode) are electrically connected in series in a stack through bi-polar plates, also known as interconnects. Shown in Figure 2 (a) is a schematic of the repeat unit for a planar stack, which is expected to be a mechanically robust, high power-density and cost-effective design. In the stack (refer to Figure 2 (b)), the interconnect is simultaneously exposed to both an oxidizing (air) environment on the cathode side and a reducing (fuels such as hydrogen or natural gas) environment on the anode side for thousands of hours at elevated temperatures (700-1,000 C). Other challenges include the fact that water vapor is likely to be present in both of these environments, and the fuel is likely to contain sulfide impurities. Also, the interconnect must be stable towards any sealing materials with which it is in contact, under numerous thermal cycles. Furthermore, the interconnect must also be stable towards electrical contact materials that are employed to minimize interfacial contact resistance, and/or the electrode materials. Considering these service environments, the interconnect materials should possess the following properties: (1) Good surface stability (resistance to oxidation and corrosion) in both cathodic (oxidizing) and anodic (reducing) atmospheres. (2) Thermal expansion matching to the ceramic PEN and other adjacent components, all of which typically have a coefficient of thermal expansion (CTE) in the range of 10.5-12.0 x 10{sup -6} K{sup -1}. (3) High electrical conductivity through both the bulk material and in-situ formed oxide scales. (4) Satisfactory bulk and interfacial mechanical/thermomechanical reliability and durability at the SOFC operating temperatures. (5) Good compatibility with other materials in contact with interconnects such as seals and electrical contact materials. Until recently, the leading candidate material for the interconnect was doped lanthanum chromite (LaCrO3), which is a ceramic material which can easily withstand the traditional 1000 C operating temperature. However, the high cost of raw materials and fabrication, difficulties in obtaining high-density chromite parts at reasonable sintering temperatures, and the tendency of the chromite interconnect to partially reduce at the fuel gas/interconnect interface, causing the component to warp and the peripheral seal to break, have plagued the commercialization of planar SOFCs for years. The recent trend in developing lower temperature, more cost-effective cells which utilize anode-supported, several micron-thin electrolytes and/or new electrolytes with improved conductivity make it feasible for lanthanum chromite to be supplanted by metals or alloys as the interconnect materials. Compared to doped lanthanum chromite, metals or alloys offer significantly lower raw material and fabrication costs.

Yang, Z Gary; Stevenson, Jeffry W.; Singh, Prabhakar

2003-06-15

164

Oxidative stress and oxidative damage in chemical carcinogenesis  

SciTech Connect

Reactive oxygen species (ROS) are induced through a variety of endogenous and exogenous sources. Overwhelming of antioxidant and DNA repair mechanisms in the cell by ROS may result in oxidative stress and oxidative damage to the cell. This resulting oxidative stress can damage critical cellular macromolecules and/or modulate gene expression pathways. Cancer induction by chemical and physical agents involves a multi-step process. This process includes multiple molecular and cellular events to transform a normal cell to a malignant neoplastic cell. Oxidative damage resulting from ROS generation can participate in all stages of the cancer process. An association of ROS generation and human cancer induction has been shown. It appears that oxidative stress may both cause as well as modify the cancer process. Recently association between polymorphisms in oxidative DNA repair genes and antioxidant genes (single nucleotide polymorphisms) and human cancer susceptibility has been shown.

Klaunig, James E., E-mail: jklauni@indiana.edu; Wang Zemin; Pu Xinzhu; Zhou Shaoyu

2011-07-15

165

Chaperones, but not oxidized proteins, are ubiquitinated after oxidative stress.  

PubMed

After oxidative stress, proteins that are oxidatively modified are degraded by the 20S proteasome. However, several studies have documented an enhanced ubiquitination of yet unknown proteins. Because ubiquitination is a prerequisite for degradation by the 26S proteasome in an ATP-dependent manner this raises the question whether these proteins are also oxidized and, if not, what proteins need to be ubiquitinated and degraded after oxidative conditions. By determination of oxidized and ubiquitinated proteins we demonstrate here that most oxidized proteins are not preferentially ubiquitinated. However, we were able to confirm an increase in ubiquitinated proteins 16 h after oxidative stress. Therefore, we isolated ubiquitinated proteins from hydrogen peroxide-treated cells, as well as from control cells and cells treated with lactacystin, an irreversible proteasome inhibitor, and identified some of these proteins by MALDI tandem mass spectrometry. As a result we obtained 24 different proteins that can be categorized into the following groups: chaperones, energy metabolism, cytoskeleton/intermediate filaments, and protein translation/ribosome biogenesis. The special set of identified, ubiquitinated proteins confirms the thesis that ubiquitination upon oxidative stress is not a random process to degrade the mass of oxidized proteins, but concerns a special group of functional proteins. PMID:22683819

Kästle, Marc; Reeg, Sandra; Rogowska-Wrzesinska, Adelina; Grune, Tilman

2012-10-01

166

Oxidation of sulfites on vanadium-molybdenum oxides  

NASA Astrophysics Data System (ADS)

The low temperature emission of 1O2 singlet oxygen from xV2O5 · yMoO3 binary oxides is investigated by means of flash desorption. Conditions for the generation of 1O2 on their surfaces are determined, along with the correlation between the amount of 1O2 and the degree of NaHSO3 conversion in the oxidation reaction. It is shown that on the surface of oxides there are oxygen species that upon decomposition produce 1O2 involved in the oxidation of HSO{3/-}.

Matrosova, O. V.; Vishnetskaya, M. V.

2014-01-01

167

Oxidation resistant alloys, method for producing oxidation resistant alloys  

DOEpatents

A method for producing oxidation-resistant austenitic alloys for use at temperatures below 800.degree. C. comprising of: providing an alloy comprising, by weight %: 14-18% chromium, 15-18% nickel, 1-3% manganese, 1-2% molybdenum, 2-4% silicon, 0% aluminum and the balance being iron; heating the alloy to 800.degree. C. for between 175-250 hours prior to use in order to form a continuous silicon oxide film and another oxide film. The method provides a means of producing stainless steels with superior oxidation resistance at temperatures above 700.degree. C. at a low cost

Dunning, John S. (Corvallis, OR); Alman, David E. (Salem, OR)

2002-11-05

168

Oxidation resistant alloys, method for producing oxidation resistant alloys  

DOEpatents

A method for producing oxidation-resistant austenitic alloys for use at temperatures below 800 C. comprising of: providing an alloy comprising, by weight %: 14-18% chromium, 15-18% nickel, 1-3% manganese, 1-2% molybdenum, 2-4% silicon, 0% aluminum and the balance being iron; heating the alloy to 800 C. for between 175-250 hours prior to use in order to form a continuous silicon oxide film and another oxide film. The method provides a means of producing stainless steels with superior oxidation resistance at temperatures above 700 C. at a low cost

Dunning, John S.; Alman, David E.

2002-11-05

169

Diluted magnetic oxides  

NASA Astrophysics Data System (ADS)

In this review, we review the progress of research on ZnO- and In2O3-based diluted magnetic oxides (DMOs). Firstly, we present the preparation and characterization of DMOs. The former includes the preparation methods and conditions, and the latter includes the characterization techniques for measuring microstructures. Secondly, we introduce the magnetic and transport properties of DMOs, as well as the relationship between them. Thirdly, the origin and mechanism of the ferromagnetism are discussed. Fourthly, we introduce other related work, including computational work and pertinent heterogeneous structures, such as multilayers and magnetic tunnel junctions. Finally, we provide an overview and outlook for DMOs.

Li, XiaoLi; Qi, ShiFei; Jiang, FengXian; Quan, ZhiYong; Xu, XiaoHong

2013-01-01

170

Oxidative metabolism in muscle.  

PubMed Central

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. PMID:9232855

Ferrari, M; Binzoni, T; Quaresima, V

1997-01-01

171

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

172

Chlorobenzene oxidation using ozone over iron oxide and manganese oxide catalysts.  

PubMed

A low-temperature catalytic oxidation of chlorobenzene (CB) has been performed at temperatures of 60-210°C using ozone (O(3)) 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 1200 ppm ozone results in a remarkable increase in CB conversion and the conversion reaches 91.7% at 150°C for iron oxide, while 81.5% conversion is achieved with manganese oxide at 90°C. The activation energy of manganese oxide (48 kJ mol(-1)) is higher than that of iron oxide (43 kJ mol(-1)) without ozone. However, as ozone is added, the activation energy is significantly reduced to 20.0 kJ mol(-1) for iron oxide. CO and CO(2) are the only carbon-containing products detected in the effluent gas stream. For the long-term test, no obvious deactivation was found in iron oxide and ozone. However, in the case of manganese oxide and ozone, 3% reduction of CB conversion was observed. Slight deactivation might be attributed to a small amount of reaction byproducts (carboxylic acid species) and residual chloride (MnCl(2)) being deposited on the active sites of the catalysts. PMID:21227575

Wang, Hou Chuan; Liang, Hsu Shang; Chang, Moo Been

2011-02-28

173

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

174

Zinc oxide varistors and/or resistors  

DOEpatents

Varistors and/or resistors are described that include 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, W.D. Jr.; Bond, W.D.; Lauf, R.J.

1993-07-27

175

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

176

Transparent conducting oxide nanotubes.  

PubMed

Thin film or porous membranes made of hollow, transparent, conducting oxide (TCO) nanotubes, with high chemical stability, functionalized surfaces and large surface areas, can provide an excellent platform for a wide variety of nanostructured photovoltaic, photodetector, photoelectrochemical and photocatalytic devices. While large-bandgap oxide semiconductors offer transparency for incident light (below their nominal bandgap), their low carrier concentration and poor conductivity makes them unsuitable for charge conduction. Moreover, materials with high conductivity have nominally low bandgaps and hence poor light transmittance. Here, we demonstrate thin films and membranes made from TiO2 nanotubes heavily-doped with shallow Niobium (Nb) donors (up to 10%, without phase segregation), using a modified electrochemical anodization process, to fabricate transparent conducting hollow nanotubes. Temperature dependent current-voltage characteristics revealed that TiO2 TCO nanotubes, doped with 10% Nb, show metal-like behavior with resistivity decreasing from 6.5 × 10(-4) ?cm at T = 300 K (compared to 6.5 × 10(-1) ?cm for nominally undoped nanotubes) to 2.2 × 10(-4) ?cm at T = 20 K. Optical properties, studied by reflectance measurements, showed light transmittance up to 90%, within wavelength range 400 nm-1000 nm. Nb doping also improves the field emission properties of TCO nanotubes demonstrating an order of magnitude increase in field-emitter current, compared to undoped samples. PMID:25180635

Alivov, Yahya; Singh, Vivek; Ding, Yuchen; Nagpal, Prashant

2014-09-26

177

Low Temperature Oxidation Catalyst  

NASA Technical Reports Server (NTRS)

One day soon homeowners everywhere may be protected from deadly carbon monoxide fumes, thanks to a device invented at NASA Langley Research Center in Hampton, Va. It uses a new class of low-temperature oxidation catalysts to convert carbon monoxide to non-toxic carbon dioxide at room temperature. It can also remove formaldehyde from the air. The catalysts initially were developed for research involving carbon dioxide lasers. Industry already has shown an interest. Rochester Gas and Electric Co., of Rochester, N.Y., has an agreement with NASA Langley to develop a product for habitable spaces such as homes, cars and aircraft. The Mantic Corp., of Salt Lake City, Utah, plans to use them in breathing apparatus, such as firefighter masks. The catalysts also have applications as trace-gas detectors, and in cold-engine emission control. To work, the catalysts - tin oxide and platinum - are applied to a surface. Air passing over the surface reacts with the catalysts, transforming carbon monoxide and formaldehyde. The device requires no energy for operation, doesn't need to be plugged in, has no moving parts and lasts a long time.

1995-01-01

178

Transparent conducting oxide nanotubes  

NASA Astrophysics Data System (ADS)

Thin film or porous membranes made of hollow, transparent, conducting oxide (TCO) nanotubes, with high chemical stability, functionalized surfaces and large surface areas, can provide an excellent platform for a wide variety of nanostructured photovoltaic, photodetector, photoelectrochemical and photocatalytic devices. While large-bandgap oxide semiconductors offer transparency for incident light (below their nominal bandgap), their low carrier concentration and poor conductivity makes them unsuitable for charge conduction. Moreover, materials with high conductivity have nominally low bandgaps and hence poor light transmittance. Here, we demonstrate thin films and membranes made from TiO2 nanotubes heavily-doped with shallow Niobium (Nb) donors (up to 10%, without phase segregation), using a modified electrochemical anodization process, to fabricate transparent conducting hollow nanotubes. Temperature dependent current-voltage characteristics revealed that TiO2 TCO nanotubes, doped with 10% Nb, show metal-like behavior with resistivity decreasing from 6.5 × 10-4 ?cm at T = 300 K (compared to 6.5 × 10-1 ?cm for nominally undoped nanotubes) to 2.2 × 10-4 ?cm at T = 20 K. Optical properties, studied by reflectance measurements, showed light transmittance up to 90%, within wavelength range 400 nm-1000 nm. Nb doping also improves the field emission properties of TCO nanotubes demonstrating an order of magnitude increase in field-emitter current, compared to undoped samples.

Alivov, Yahya; Singh, Vivek; Ding, Yuchen; Nagpal, Prashant

2014-09-01

179

Imaging gate oxide ruptures  

NASA Astrophysics Data System (ADS)

As minimum feature sizes are reduced in MOS silicon devices, dielectric breakdown continues to pose a formidable challenge. A more complete understanding of the failure mechanism which induces oxide rupture has become an absolute necessity in order to meet the advancing yield and reliability requirements of today's complex integrated structures. This paper will present an interesting insight into the nature of dielectric breakdown in MOS transistors produced from a novel cross-sectioning TEM sample preparation method using a focused ion beam tool. By using deductive failure analysis, it was possible to determine the location of the leakage within a 1000 angstroms portion of the transfer gate of a one megabit DRAM. Once localized, a creative combination of conventional glass lapping and focused ion beam techniques were used to produce the thin TEM slice which contained the oxide breakdown. An image of the breakdown was then obtained on a 200 keV TEM. Interestingly, the image revealed that the origin of the breakdown was associated with imperfections in the form of voids in the surface of the silicon substrate. These results proved to be consistent over multiple samples. In this paper a complete description of these images will be presented along with possible theories describing the fundamental origin of these defects.

Mendez, Horacio; Morris, Steve; Tatti, Sudhindra; Dickson, Nicholas; Pyle, Ronald E.

1993-01-01

180

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 â 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

181

Chromium(III) Oxidation by Three Poorly-Crystalline Manganese(IV) Oxides. 1. Chromium(III)-Oxidizing Capacity  

E-print Network

Chromium(III) Oxidation by Three Poorly-Crystalline Manganese(IV) Oxides. 1. Chromium(III)-Oxidizing States *S Supporting Information ABSTRACT: The Cr(III)-oxidizing capacity of three layered poorly in the system, indicated that the Cr(III) oxidation reaction had ceased between 30 min and 1 h under most

Sparks, Donald L.

182

Circulating plants for oxidative recrystallization of oxide fuel  

Microsoft Academic Search

In pilot plants being designed for the regeneration of spent fuel from fast reactors on the basis of gaseous-fluoride technology mechanical methods (roll breaker, ball mill) are used to grind spent oxide fuel whose cladding has been melted off. Another promising method is that of chemical-thermal dispersal of fuel (oxidative recrystallization), which ensures separation and selective trapping of volatile flssuion

G. M. Vinogradov; G. D. Kosenko; Yu. A. Usenko; V. A. Chemezov

1987-01-01

183

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...

184

Reduced graphene oxide for catalytic oxidation of aqueous organic pollutants.  

PubMed

We discovered that chemically reduced graphene oxide, with an I(D)/I(G) >1.4 (defective to graphite) can effectively activate peroxymonosulfate (PMS) to produce active sulfate radicals. The produced sulfate radicals (SO(4)(•-)) are powerful oxidizing species with a high oxidative potential (2.5-3.1 vs 2.7 V of hydroxyl radicals), and can effectively decompose various aqueous contaminants. Graphene demonstrated a higher activity than several carbon allotropes, such as activated carbon (AC), graphite powder (GP), graphene oxide (GO), and multiwall carbon nanotube (MWCNT). Kinetic study of graphene catalyzed activation of PMS was carried out. It was shown that graphene catalysis is superior to that on transition metal oxide (Co(3)O(4)) in degradation of phenol, 2,4-dichlorophenol (DCP) and a dye (methylene blue, MB) in water, therefore providing a novel strategy for environmental remediation. PMID:22967012

Sun, Hongqi; Liu, Shizhen; Zhou, Guanliang; Ang, Ha Ming; Tadé, Moses O; Wang, Shaobin

2012-10-24

185

Room Temperature Chemical Oxidation of Delafossite-Type Oxides  

NASA Astrophysics Data System (ADS)

Examination of the delafossite-type structure of CuLaO 2 and CuYO 2 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 Cu 2+. Reaction with hypohalites in an aqueous solution leads to color change. Evidence of the formation of Cu 2+ 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 CuLaO 2+ x appears as a single phase, CuYO 2+ 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

186

Oxidation mechanism of nickel oxide/carbon nanotube composite.  

PubMed

The oxidation mechanism and thermal stability of nickel oxide (NiO)/carbon nanotube (CNT) composites were investigated by examining composites with different NiO contents by thermogravimetric analysis and transmission electron microscopy (TEM). NiO acts as a catalyst in the oxidation of CNT in the composite. CNTs can be oxidized, even in a vacuum, by reducing NiO to nickel at temperatures lower than the normal oxidation temperature of CNTs. This phase transition was confirmed directly by in situ heating TEM observations. In air, reduction by CNT occurs simultaneously with reoxidation by gaseous O? molecules, and NiO maintains its phase. The thermal stability decreased with increasing NiO content because of defects in the CNT generated by the NiO loading. PMID:23920206

Kim, Tae-Hoon; Park, Min-Ho; Ryu, Jiho; Yang, Cheol-Woong

2013-08-01

187

Operation of staged membrane oxidation reactor systems  

DOEpatents

A method of operating a multi-stage ion transport membrane oxidation system. The method comprises providing a multi-stage ion transport membrane oxidation system with at least a first membrane oxidation stage and a second membrane oxidation stage, operating the ion transport membrane oxidation system at operating conditions including a characteristic temperature of the first membrane oxidation stage and a characteristic temperature of the second membrane oxidation stage; and controlling the production capacity and/or the product quality by changing the characteristic temperature of the first membrane oxidation stage and/or changing the characteristic temperature of the second membrane oxidation stage.

Repasky, John Michael

2012-10-16

188

Oxidation and low cycle fatigue life prediction  

NASA Technical Reports Server (NTRS)

When a metallic material is exposed to a high temperature in an ambient atmosphere, oxidation takes place on the metallic surface. The formed oxides (both surface and grain boundary oxides) are mechanically brittle so that if the stress is high enough the oxides will be cracked. The grain boundary oxide formation in TAZ-8A nickel-base superalloy was studied. The effect of oxide crack nucleus on low cycle fatigue life will be analyzed. The TAZ-8A was subjected to high temperature oxidation tests in air under the stress-free condition. The oxidation temperatures were 600, 800, and 1000 C. The oxidation time varies from 10 to 1000 hours.

Oshida, Y.; Liu, H. W.

1984-01-01

189

High temperature oxidation resistant cermet compositions  

NASA Technical Reports Server (NTRS)

Cermet compositions are designed to provide high temperature resistant refractory coatings on stainless steel or molybdenum substrates. A ceramic mixture of chromium oxide and aluminum oxide form a coating of chromium oxide as an oxidation barrier around the metal particles, to provide oxidation resistance for the metal particles.

Phillips, W. M. (inventor)

1976-01-01

190

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

191

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. 14 figures.

Katz, J.L.; Chenghung Hung.

1993-12-07

192

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

193

Solid oxide fuel cells.  

PubMed

Despite being first demonstrated over 160 years ago, and offering significant environmental benefits and high electrical efficiency, it is only in the last two decades that fuel cells have offered a realistic prospect of being commercially viable. The solid oxide fuel cell (SOFC) offers great promise and is presently the subject of intense research activity. Unlike other fuel cells the SOFC is a solid-state device which operates at elevated temperatures. This review discusses the particular issues facing the development of a high temperature solid-state fuel cell and the inorganic materials currently used and under investigation for such cells, together with the problems associated with operating SOFCs on practical hydrocarbon fuels. PMID:12596542

Ormerod, R Mark

2003-01-01

194

Biological water oxidation.  

PubMed

Photosystem II (PSII), a multisubunit pigment-protein supercomplex found in cyanobacteria, algae, and plants, catalyzes a unique reaction in nature: the light-driven oxidation of water. Remarkable recent advances in the structural analysis of PSII now give a detailed picture of the static supercomplex on the molecular level. These data provide a solid foundation for future functional studies, in particular the mechanism of water oxidation and oxygen release. The catalytic core of the PSII is a tetramanganese-calcium cluster (Mn?O?Ca), commonly referred to as the oxygen-evolving complex (OEC). The function of the OEC rests on its ability to cycle through five metastable states (Si, i = 0-4), transiently storing four oxidizing equivalents, and in so doing, facilitates the four electron water splitting reaction. While the latest crystallographic model of PSII gives an atomic picture of the OEC, the exact connectivity within the inorganic core and the S-state(s) that the X-ray model represents remain uncertain. In this Account, we describe our joint experimental and theoretical efforts to eliminate these ambiguities by combining the X-ray data with spectroscopic constraints and introducing computational modeling. We are developing quantum chemical methods to predict electron paramagnetic resonance (EPR) parameters for transition metal clusters, especially focusing on spin-projection approaches combined with density functional theory (DFT) calculations. We aim to resolve the geometric and electronic structures of all S-states, correlating their structural features with spectroscopic observations to elucidate reactivity. The sequence of manganese oxidations and concomitant charge compensation events via proton transfer allow us to rationalize the multielectron S-state cycle. EPR spectroscopy combined with theoretical calculations provides a unique window into the tetramangenese complex, in particular its protonation states and metal ligand sphere evolution, far beyond the scope of static techniques such as X-ray crystallography. This approach has led, for example, to a detailed understanding of the EPR signals in the S?-state of the OEC in terms of two interconvertible, isoenergetic structures. These two structures differ in their valence distribution and spin multiplicity, which has important consequences for substrate binding and may explain its low barrier exchange with solvent water. New experimental techniques and innovative sample preparations are beginning to unravel the complex sequence of substrate uptake/inclusion, which is coupled to proton release. The introduction of specific site perturbations, such as replacing Ca²? with Sr²?, provides discrete information about the ligand environment of the individual Mn ions. In this way, we have identified a potential open coordination site for one Mn center, which may serve as a substrate binding site in the higher S-states, such as S? and S?. In addition, we can now monitor the binding of the substrate water in the lower S-states (S? and S?) using new EPR-detected NMR spectroscopies. These studies provided the first evidence that one of the substrates is subsumed into the complex itself and forms an oxo-bridge between two Mn ions. This result places important new restrictions on the mechanism of O-O bond formation. These new insights from nature's water splitting catalyst provide important criteria for the rational design of bioinspired synthetic catalysts. PMID:23506074

Cox, Nicholas; Pantazis, Dimitrios A; Neese, Frank; Lubitz, Wolfgang

2013-07-16

195

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

196

OXIDATION AND SORPTION KINETICS OF ARSENIC ON A POORLY CRYSTALLINE MANGANESE OXIDE  

E-print Network

OXIDATION AND SORPTION KINETICS OF ARSENIC ON A POORLY CRYSTALLINE MANGANESE OXIDE by Brandon J. Lafferty All Rights Reserved #12;OXIDATION AND SORPTION KINETICS OF ARSENIC ON A POORLY CRYSTALLINE MANGANESE OXIDE by Brandon J. Lafferty Approved

Sparks, Donald L.

197

REVIEW: Porous Anodic Metal Oxides  

NASA Astrophysics Data System (ADS)

Porous anodic aluminium oxide (AAO) and anodic titanium oxide (ATO) attracted an increased attention in the recent years due to their high potentials of application in nanotechnology. This article presents a brief review of some important developments of these smart materials including anodization methods, formation mechanisms of the pores, self-ordering processes and applications. Anodization of other metals are also highlighted.

Su, Zixue; Zhou, Wuzong

2008-01-01

198

Novel Properties in Oxide Heterostructures  

Microsoft Academic Search

A brief review of recent investigations in oxide heterostructures is presented. First, experimental results are shown. Positive colossal magnetoresistance with high sensitivities are obtained at low magnetic field (<1000 Oe) nearly at room temperature. Picoseconds photoelectric effects of the rise time ~ 210 ps and the half-maximum ~ 650 ps are also found in some oxide heterostructures. Furthermore, resistance switching

Chen Ge; Kui-Juan Jin; Hui-Bin Lu; Cong Wang

2009-01-01

199

Biochemistry of dissimilatory sulfur oxidation  

SciTech Connect

Our goals of this research are to define the substrate oxidation pathways, the electron transport mechanisms, and the modes of energy conservation employed during the dissimilatory oxidation of sulfur by thiobacilli. We have purified APS reductase to electrophoratic homogeneity from cell-free extracts of Thiobacillus denitrificans. Sufficient protein is available to initiate the production of polyclonal antibodies and to perform the kinetic experiments.

Blake, R. II.

1992-01-01

200

Automated analysis of oxidative metabolites  

NASA Technical Reports Server (NTRS)

An automated system for the study of drug metabolism is described. The system monitors the oxidative metabolites of aromatic amines and of compounds which produce formaldehyde on oxidative dealkylation. It includes color developing compositions suitable for detecting hyroxylated aromatic amines and formaldehyde.

Furner, R. L. (inventor)

1974-01-01

201

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...

202

Oxidative Imbalance and Anxiety Disorders  

PubMed Central

The oxidative imbalance appears to have an important role in anxiety development. Studies in both humans and animals have shown a strong correlation between anxiety and oxidative stress. In humans, for example, the increased malondialdehyde levels and discrepancies in antioxidant enzymes in erythrocytes have been observed. In animals, several studies also show that anxiety-like behavior is related to the oxidative imbalance. Moreover, anxiety-like behavior can be caused by pharmacological-induced oxidative stress. Studies using knockout or overexpression of antioxidant enzymes have shown a relationship between anxiety-like behavior and oxidative stress. Related factors of oxidative stress that could influence anxious behavior are revised, including impaired function of different mitochondrial proteins, inflammatory cytokines, and neurotrophic factors. It has been suggested that a therapy specifically focus in reducing reactive species production may have a beneficial effect in reducing anxiety. However, the neurobiological pathways underlying the effect of oxidative stress on anxiety symptoms are not fully comprehended. The challenge now is to identify the oxidative stress mechanisms likely to be involved in the induction of anxiety symptoms. Understanding these pathways could help to clarify the neurobiology of the anxiety disorder and provide tools for new discovery in therapies and preventive strategies. PMID:24669212

R, Krolow; D. M, Arcego; C, Noschang; S. N, Weis; C, Dalmaz

2014-01-01

203

Metal oxide nanowires gas sensors  

Microsoft Academic Search

Metal oxides are an attractive and heterogeneous class of materials covering the entire range from metals to semiconductors and insulators and almost all aspects of material science and physics in areas including superconductivity and magnetism. As far as chemical sensing is concerned it has been known, from more than five decades, that the electrical conductivity of metal oxides semiconductors varies

E. Comini

2008-01-01

204

Metal oxide films on metal  

DOEpatents

A structure including a thin film of a conductive alkaline earth metal oxide selected from the group consisting of strontium ruthenium trioxide, calcium ruthenium trioxide, barium ruthenium trioxide, lanthanum-strontium cobalt oxide or mixed alkaline earth ruthenium trioxides thereof upon a thin film of a noble metal such as platinum is provided.

Wu, Xin D. (Los Alamos, NM); Tiwari, Prabhat (Los Alamos, NM)

1995-01-01

205

Model compounds for the determination of organic and total phosphorus dissolved in natural waters  

Microsoft Academic Search

The choice of model compounds for checking the recovery of dissolved organic and total dissolved phosphorus in natural waters is discussed. Ten compounds were compared for their recovery in fresh and seawater. Four different oxidative procedures were used: acidic and alkaline persulfate oxidation, continuous flow UV irradiation and high-temperature combustion (HTC). Certain compounds have been shown to decompose when heated

Roger Kérouel; Alain Aminot

1996-01-01

206

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

207

Nitric oxide signaling in plants.  

PubMed

Plants have four nitric oxide synthase (NOS) enzymes. NOS1 appears mitochondrial, and inducible nitric oxide synthase (iNOS) chloroplastic. Distinct peroxisomal and apoplastic NOS enzymes are predicted. Nitrite-dependent NO synthesis is catalyzed by cytoplasmic nitrate reductase or a root plasma membrane enzyme, or occurs nonenzymatically. Nitric oxide undergoes both catalyzed and uncatalyzed oxidation. However, there is no evidence of reaction with superoxide, and S-nitrosylation reactions are unlikely except during hypoxia. The only proven direct targets of NO in plants are metalloenzymes and one metal complex. Nitric oxide inhibits apoplastic catalases/ascorbate peroxidases in some species but may stimulate these enzymes in others. Plants also have the NO response pathway involving cGMP, cADPR, and release of calcium from internal stores. Other known targets include chloroplast and mitochondrial electron transport. Nitric oxide suppresses Fenton chemistry by interacting with ferryl ion, preventing generation of hydroxyl radicals. Functions of NO in plant development, response to biotic and abiotic stressors, iron homeostasis, and regulation of respiration and photosynthesis may all be ascribed to interaction with one of these targets. Nitric oxide function in drought/abscisic acid (ABA)-induction of stomatal closure requires nitrate reductase and NOS1. Nitric oxide synthasel likely functions to produce sufficient NO to inhibit photosynthetic electron transport, allowing nitrite accumulation. Nitric oxide is produced during the hypersensitive response outside cells undergoing programmed cell death immediately prior to loss of plasma membrane integrity. A plasma membrane lipid-derived signal likely activates apoplastic NOS. Nitric oxide diffuses within the apoplast and signals neighboring cells via hydrogen peroxide (H2O2)-dependent induction of salicylic acid biosynthesis. Response to wounding appears to involve the same NOS and direct targets. PMID:16492476

Shapiro, Allan D

2005-01-01

208

Self-limited oxide formation in Ni(111) oxidation  

NASA Astrophysics Data System (ADS)

The oxidation of the Ni(111) surface is studied experimentally with low-energy electron microscopy and theoretically by calculating the electron reflectivity for realistic models of the NiO/Ni(111) surface with an ab initio scattering theory. Oxygen exposure at 300 K under ultrahigh-vacuum conditions leads to the formation of a continuous NiO(111)-like film consisting of nanosized domains. At 750 K, we observe the formation of a nanoheterogeneous film composed primarily of NiO(111) surface oxide nuclei, which exhibit virtually the same energy-dependent reflectivity as in the case of 300 K and which are separated by oxygen-free Ni(111) terraces. The scattering theory explains the observed normal incidence reflectivity R(E) of both the clean and the oxidized Ni(111) surface. At low energies, R(E) of the oxidized surface is determined by a forbidden gap in the k?=0 projected energy spectrum of the bulk NiO crystal. However, for both low- and high-temperature oxidation, a rapid decrease of the reflectivity in approaching zero kinetic energy is experimentally observed. This feature is shown to characterize the thickness of the oxide layer, suggesting an average oxide thickness of two NiO layers.

Flege, J. Ingo; Meyer, Axel; Falta, Jens; Krasovskii, Eugene E.

2011-09-01

209

Reproductive Benefit of Oxidative Damage: An Oxidative Stress "Malevolence"?  

PubMed Central

High levels of reactive oxygen species (ROS) compared to antioxidant defenses are considered to play a major role in diverse chronic age-related diseases and aging. Here we present an attempt to synthesize information about proximate oxidative processes in aging (relevant to free radical or oxidative damage hypotheses of aging) with an evolutionary scenario (credited here to Dawkins hypotheses) involving tradeoffs between the costs and benefits of oxidative stress to reproducing organisms. Oxidative stress may be considered a biological imperfection; therefore, the Dawkins' theory of imperfect adaptation of beings to environment was applied to the role of oxidative stress in processes like famine and infectious diseases and their consequences at the molecular level such as mutations and cell signaling. Arguments are presented that oxidative damage is not necessarily an evolutionary mistake but may be beneficial for reproduction; this may prevail over its harmfulness to health and longevity in evolution. Thus, Dawkins' principle of biological “malevolence” may be an additional biological paradigm for explaining the consequences of oxidative stress. PMID:21969876

Poljsak, B.; Milisav, I.; Lampe, T.; Ostan, I.

2011-01-01

210

46 CFR 153.1010 - Alkylene oxides.  

Code of Federal Regulations, 2011 CFR

...washed away immediately. (c) While alkylene oxides are onboard the vessel, the master shall make sure that the oxygen content...Tankships with independent piping for alkylene oxides must have onboard: (1) Alkylene oxide handling plans approved by the...

2011-10-01

211

EFFECTS OF PHOTOCHEMICAL OXIDANTS ON PLANTS  

EPA Science Inventory

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 hydrocarbons, their precursors. Th...

212

Partial oxidation of methane over bimetallic nickel–lanthanide oxides  

Microsoft Academic Search

The study of partial oxidation of methane (POM) over bimetallic nickel–lanthanide oxides was undertaken. Binary intermetallic compounds of the type LnNi (Ln=Pr, Gd, Lu) were used as bimetallic nickel–lanthanide oxides precursors and the products (NiO·Pr2NiO4, 2NiO·Gd2O3 and 2NiO·Lu2O3) were characterized by means of X-ray diffraction, X-ray photoelectron spectroscopy, Raman and temperature programmed reduction. The catalytic activity increases when gadolinium or

Ana C. Ferreira; A. M. Ferraria; A. M. Botelho do Rego; António P. Gonçalves; M. Rosário Correia; T. Almeida Gasche; Joaquim B. Branco

2010-01-01

213

Ethanol oxidation on metal oxide-supported platinum catalysts  

SciTech Connect

Ethanol is a renewable fuel that can be used as an additive to gasoline (or its substitute) with the advantage of octane enhancement and reduced carbon monoxide exhaust emissions. However, on Ethanol is a renewable fuel that can be used as an additive to gasoline (or its substitute) with the advantage of octane enhancement and reduced carbon monoxide exhaust emissions. However, on the standard three-way catalysts, the conversion of unburned ethanol is low because both ethanol and some of its partially oxidized derivatives are highly resistant to oxidation. A combination of first-principles density-functional theory (DFT) based calculations and in-situ diffuse reflectance infrared spectroscopy (DRIFTS) analysis was applied to uncover some of the fundamental phenomena associated with ethanol oxidation on Pt containing catalysts. In particular, the objective was to analyze the role of the oxide (i.e., ?-Al2O3 or SiO2) substrate on the ethanol oxidation activity. The results showed that Pt nanoparticles trap and accumulate oxygen at their surface and perimeter sites and play the role of “stoves” that burn ethanol molecules and their partially oxidized derivatives to the “final” products. The ?-Al2O3 surfaces provided higher mobility of the fragments of ethanol molecules than the SiO2 surface and hence increased the supply rate of these objects to the Pt particles. This will in turn produce a higher conversion rate of unburned ethanol.and some of its partially oxidized derivatives are highly resistant to oxidation. A combination of first-principles density-functional theory (DFT) based calculations and in-situ diffuse reflectance infrared spectroscopy (DRIFTS) analysis was applied to uncover some of the fundamental phenomena associated with ethanol oxidation on Pt containing catalysts. In particular, the objective was to analyze the role of the oxide (i.e., ?-Al2O3 or SiO2) substrate on the ethanol oxidation activity. The results showed that Pt nanoparticles trap and accumulate oxygen at their surface and perimeter sites and play the role of “stoves” that burn ethanol molecules and their partially oxidized derivatives to the “final” products. The ?-Al2O3 surfaces provided higher mobility of the fragments of ethanol molecules than the SiO2 surface and hence increased the supply rate of these objects to the Pt particles. This will in turn produce a higher conversion rate of unburned ethanol.

L. M. Petkovic 090468; Sergey N. Rashkeev; D. M. Ginosar

2009-09-01

214

Surface-Step-Induced Oscillatory Oxide Growth  

NASA Astrophysics Data System (ADS)

We report in situ atomic-resolution transmission electron microscopy observations of the oxidation of stepped Cu surfaces. We find that the presence of surface steps both inhibits oxide film growth and leads to the oxide decomposition, thereby resulting in oscillatory oxide film growth. Using atomistic simulations, we show that the oscillatory oxide film growth is induced by oxygen adsorption on the lower terrace along the step edge, which destabilizes the oxide film formed on the upper terrace.

Li, Liang; Luo, Langli; Ciston, Jim; Saidi, Wissam A.; Stach, Eric A.; Yang, Judith C.; Zhou, Guangwen

2014-09-01

215

Surface-step-induced oscillatory oxide growth.  

PubMed

We report in situ atomic-resolution transmission electron microscopy observations of the oxidation of stepped Cu surfaces. We find that the presence of surface steps both inhibits oxide film growth and leads to the oxide decomposition, thereby resulting in oscillatory oxide film growth. Using atomistic simulations, we show that the oscillatory oxide film growth is induced by oxygen adsorption on the lower terrace along the step edge, which destabilizes the oxide film formed on the upper terrace. PMID:25302908

Li, Liang; Luo, Langli; Ciston, Jim; Saidi, Wissam A; Stach, Eric A; Yang, Judith C; Zhou, Guangwen

2014-09-26

216

Mammalian mitochondrial beta-oxidation.  

PubMed Central

The enzymic stages of mammalian mitochondrial beta-oxidation were elucidated some 30-40 years ago. However, the discovery of a membrane-associated multifunctional enzyme of beta-oxidation, a membrane-associated acyl-CoA dehydrogenase and characterization of the carnitine palmitoyl transferase system at the protein and at the genetic level has demonstrated that the enzymes of the system itself are incompletely understood. Deficiencies of many of the enzymes have been recognized as important causes of disease. In addition, the study of these disorders has led to a greater understanding of the molecular mechanism of beta-oxidation and the import, processing and assembly of the beta-oxidation enzymes within the mitochondrion. The tissue-specific regulation, intramitochondrial control and supramolecular organization of the pathway is becoming better understood as sensitive analytical and molecular techniques are applied. This review aims to cover enzymological and organizational aspects of mitochondrial beta-oxidation together with the biochemical aspects of inherited disorders of beta-oxidation and the intrinsic control of beta-oxidation. PMID:8973539

Eaton, S; Bartlett, K; Pourfarzam, M

1996-01-01

217

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. PMID:6051342

Silverman, Melvin P.

1967-01-01

218

Oxidation kinetics of aluminum diboride  

NASA Astrophysics Data System (ADS)

The oxidation characteristics of aluminum diboride (AlB2) and a physical mixture of its constituent elements (Al+2B) were studied in dry air and pure oxygen using thermal gravimetric analysis to obtain non-mechanistic kinetic parameters. Heating in air at a constant linear heating rate of 10 °C/min showed a marked difference between Al+2B and AlB2 in the onset of oxidation and final conversion fraction, with AlB2 beginning to oxidize at higher temperatures but reaching nearly complete conversion by 1500 °C. Kinetic parameters were obtained in both air and oxygen using a model-free isothermal method at temperatures between 500 and 1000 °C. Activation energies were found to decrease, in general, with increasing conversion for AlB2 and Al+2B in both air and oxygen. AlB2 exhibited O2-pressure-independent oxidation behavior at low conversions, while the activation energies of Al+2B were higher in O2 than in air. Differences in the composition and morphology between oxidized Al+2B and AlB2 suggested that Al2O3-B2O3 interactions slowed Al+2B oxidation by converting Al2O3 on aluminum particles into a Al4B2O9 shell, while the same Al4B2O9 developed a needle-like morphology in AlB2 that reduced oxygen diffusion distances and increased conversion. The model-free kinetic analysis was critical for interpreting the complex, multistep oxidation behavior for which a single mechanism could not be assigned. At low temperatures, moisture increased the oxidation rate of Al+2B and AlB2, but both appear to be resistant to oxidation in cool, dry environments.

Whittaker, Michael L.; Sohn, H. Y.; Cutler, Raymond A.

2013-11-01

219

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

2013-11-01

220

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

221

Room temperature chemical oxidation of delafossite-type oxides  

SciTech Connect

Examination of the delafossite-type structure of CuLaO[sub 2] and CuYO[sub 2] suggests that there is room enough to accommodate intercalated oxide ions and the charge compensation resulting simply from the oxidation of an equivalent amount of Cu[sup +] into Cu[sup 2+]. Reaction with hypohalites in an aqueous solution leads to color change. Evidence of the formation of Cu[sup 2+] 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 CuLaO[sub 2+x] appears as a single phase, CuYO[sub 2+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. Comparison is stressed between the oxides obtained at higher temperatures.

Trari, M.; Toepfer, J.; Doumerc, J.P.; Pouchard, M.; Hagenmuller, P. (Laboratoire de Chimie du Solide du CNRS, Talence (France)); Ammar, A. (Universite Cadi Ayyad, Marrakech (Morocco))

1994-07-01

222

Growth of nitrite-oxidizing bacteria by aerobic hydrogen oxidation.  

PubMed

The bacterial oxidation of nitrite to nitrate is a key process of the biogeochemical nitrogen cycle. Nitrite-oxidizing bacteria are considered a highly specialized functional group, which depends on the supply of nitrite from other microorganisms and whose distribution strictly correlates with nitrification in the environment and in wastewater treatment plants. On the basis of genomics, physiological experiments, and single-cell analyses, we show that Nitrospira moscoviensis, which represents a widely distributed lineage of nitrite-oxidizing bacteria, has the genetic inventory to utilize hydrogen (H2) as an alternative energy source for aerobic respiration and grows on H2 without nitrite. CO2 fixation occurred with H2 as the sole electron donor. Our results demonstrate a chemolithoautotrophic lifestyle of nitrite-oxidizing bacteria outside the nitrogen cycle, suggesting greater ecological flexibility than previously assumed. PMID:25170152

Koch, Hanna; Galushko, Alexander; Albertsen, Mads; Schintlmeister, Arno; Gruber-Dorninger, Christiane; Lücker, Sebastian; Pelletier, Eric; Le Paslier, Denis; Spieck, Eva; Richter, Andreas; Nielsen, Per H; Wagner, Michael; Daims, Holger

2014-08-29

223

Photopromoted and Thermal Decomposition of Nitric Oxide by Metal Oxides.  

National Technical Information Service (NTIS)

This technical report summarizes research on decomposition of NOx by photopromoted and thermal solid-catalyzed decomposition of NO. Typical catalysts incorporated one or more metal oxides. Photopromotion of catalytic activity was observed with several cat...

E. Berman, J. Dong, N. N. Lichtin

1992-01-01

224

Intracellular oxidation of hydroethidine: Compartmentalization and cytotoxicity of oxidation products.  

PubMed

Hydroethidine (HE) is a blue fluorescent dye that is intracellularly converted into red-emitting products on two-electron oxidation. One of these products, namely 2-hydroxyethidium, is formed as the result of HE superoxide anion-specific oxidation, and so HE is widely used for the detection of superoxide in cells and tissues. In our experiments we exploited three cell lines of different origin: K562 (human leukemia cells), A431 (human epidermoid carcinoma cells), and SCE2304 (human mesenchymal stem cells derived from endometrium). Using fluorescent microscopy and flow cytometry analysis, we showed that HE intracellular oxidation products accumulate mostly in the cell mitochondria. This accumulation provokes gradual depolarization of mitochondrial membrane, affects oxygen consumption rate in HE-treated cells, and causes cellular apoptosis in the case of high HE concentrations and/or long cell incubations with HE, as well as a high rate of HE oxidation in cells exposed to some stimuli. PMID:25035077

Lyublinskaya, O G; Zenin, V V; Shatrova, A N; Aksenov, N D; Zemelko, V I; Domnina, A P; Litanyuk, A P; Burova, E B; Gubarev, S S; Negulyaev, Y A; Nikolsky, N N

2014-10-01

225

Partial oxidation process  

SciTech Connect

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 concentrated in the grey water that separates out in the decanter in the carbon recovery section. The concentration of ash suspended in the grey water may be then easily reduced in a solids-liquid separator with or without the addition of a flocculant and prior to recycling a portion of the grey water to the gas quench tank and/or gas scrubber. Further, the ash suspended in the carbon-soot-liquid hydrocarbonaceous fuel stream from the bottom of the liquid organic extractant still may be optionally reduced in another solids-liquid separator prior to recycling a portion of said stream to the gas generator as part of the hydrocarbonaceous reactant fuel feed.

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

1984-08-21

226

Oxidants from Pulverized Minerals  

NASA Astrophysics Data System (ADS)

Joel Hurowitz (previously at State University of New York at Stony Brook and now at the Jet Propulsion Laboratory), Nick Tosca, Scott McLennan, and Martin Schoonen (SUNY at Stony Brook) studied the production of hydrogen peroxide from freshly pulverized minerals in solution. Their experiments focused on olivine, augite, and labradorite; silicate minerals of basaltic planetary surfaces, such as the Moon and Mars, that are exposed to the intense crushing and grinding of impact cratering processes. The hydrogen peroxide produced in the experiments was enough to adequately explain the oxidizing nature of Martian regolith first determined by the Viking Landers and the results suggest, for the first time, that mechanically activated mineral surfaces may be an important part of the overall explanation for the Viking Lander biology experiment results. Hurowitz and coauthors further showed that when the pulverized minerals are heat-treated to high temperature under vacuum (to cause dehydroxylation) there is almost a 20 times increase in hydrogen peroxide production, a result which may be highly relevant to lunar dust. These careful studies demonstrate the importance of and concern about reactive dusts on planetary surfaces from two standpoints: the health of astronauts on surface maneuvers who may inadvertently breath it and the viability of possible Martian organic species to survive in such a corrosive, antiseptic surface environment.

Martel, L. M. V.

2007-06-01

227

Detailed mechanism of benzene oxidation  

NASA Technical Reports Server (NTRS)

A detailed quantitative mechanism for the oxidation of benzene in both argon and nitrogen diluted systems is presented. Computed ignition delay time for argon diluted mixtures are in satisfactory agreement with experimental results for a wide range of initial conditions. An experimental temperature versus time profile for a nitrogen diluted oxidation was accurately matched and several concentration profiles were matched qualitatively. Application of sensitivity analysis has given approximate rate constant expressions for the two dominant heat release reactions, the oxidation of C6H5 and C5H5 radicals by molecular oxygen.

Bittker, David A.

1987-01-01

228

Improved 4H-SiC metal oxide semiconductor interface produced by using an oxidized SiN gate oxide that had undergone post-oxidation annealing  

NASA Astrophysics Data System (ADS)

We investigated oxidized SiN gate oxides that have undergone post-oxidation annealing (POA) treatment using diluted O2 (10% O2 in N2) at 1100 °C. The oxidized SiN/SiC interfaces were characterized by using capacitance-voltage (C-V) measurements, Auger electron spectroscopy (AES), high-resolution transmission electron microscopy (HR-TEM), and X-ray photoelectron spectroscopy (XPS). POA for 60 min significantly improved the interface trap density (D it ), near-interface trap density (N it ), and effective oxide charge density (Q eff ) of the oxidized SiN. However, improvement was not observed for the as-oxidized SiN sample or the oxidized SiN sample that had undergone POA for 120 min. The electrical properties of metal-oxide semiconductor devices fabricated using these oxides are discussed in terms of the oxide chemical composition.

Moon, Jeong Hyun; Bahng, Wook; Kang, In Ho; Kim, Sang Cheol; Na, Moon Geong; Kim, Nam-Kyun

2014-05-01

229

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

230

Oxidative stress tolerance in plants  

PubMed Central

Biotic and abiotic stress conditions produce reactive oxygen species (ROS) in plants causing oxidative stress damage. At the same time, ROS have additional signaling roles in plant adaptation to the stress. It is not known how the two seemingly contrasting functional roles of ROS between oxidative damage to the cell and signaling for stress protection are balanced. Research suggests that the plant growth regulator auxin may be the connecting link regulating the level of ROS and directing its role in oxidative damage or signaling in plants under stress. The objective of this review is to highlight some of the recent research on how auxin’s role is intertwined to that of ROS, more specifically H2O2, in plant adaptation to oxidative stress conditions. PMID:23887492

Krishnamurthy, Aparna; Rathinasabapathi, Bala

2013-01-01

231

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

232

Preparation and properties of electrically conducting ceramics based on indium oxide-rare earth oxides-hafnium oxides  

SciTech Connect

Electrically conducting refractory oxides based on adding indium oxide to rare earth-stabilized hafnium oxide are being studied for use in magnetohydrodynamic (MHD) generators, fuel cells, and thermoelectric generators. The use of indium oxide generally increases the electrical conductivity. The results of measurements of the electrical conductivity and data on corrosion resistance in molten salts are presented.

Marchant, D.D.; Bates, J.L.

1983-09-01

233

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

234

Oxidation-resistant fiber coatings for non-oxide ceramic composites  

SciTech Connect

Oxidation of fiber/matrix interfaces can degrade the strength and toughness of ceramic composites containing non-oxide constituents. Oxidation can occur when the fiber ends are exposed or in the presence of cracks. Theoretical considerations indicate that, contrary to popular belief, oxide fiber coatings should be worse than non-oxide fiber coatings for protection against oxidation. Furthermore, oxidation of fiber/matrix interfaces is a composite system problem rather than that of the fiber coating.

Luthra, K.L. [General Electric Corporate Research and Development, Schenectady, NY (United States)

1997-12-01

235

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

236

Nitrous Oxide Transport and Transformation  

NSDL National Science Digital Library

In this laboratory exercise, students add nitrous oxide to pairs of undisturbed soil cores. One core in each set of cores is treated with acetylene to block nitrous oxide transformation. The bulk of this exercise involves, injection and drawing of air samples. Students gain experience manipulating gas concentration data, determining soil properties related to transport of gases through porous medium like soils. This exercise is appropriate for soil physics and biogeochemistry courses.

Jacinthe, Pierre-Andre

237

Oxidation protection coatings for polymers  

NASA Technical Reports Server (NTRS)

A polymeric substrate is coated with a metal oxide film to provide oxidation protection in low Earth orbital environments. The film contains about 4 volume percent polymer to provide flexibility. A coil of polymer material moves through an ion beam as it is fed between reels. The ion beam first cleans the polymer material surface and then sputters the film material from a target onto this surface.

Mirtich, M. J.; Sovey, J. S.; Banks, B. A. (inventors)

1985-01-01

238

The catalytic oxidation of propane  

E-print Network

THE CATALYTIC OXIDATION OP PROPANE A Thesis By Charles Frederick Sandersont * * June 1949 Approval as to style and content recommended: Head of the Department of Chemical Engineering THE CATALYTICi OXIDATTON OF PROPANE A Thesis By Charles... Frederick ;Sandersonit * June 1949 THE CATALYTIC OXIDATION OP PROPANE A Thesis Submitted to the Faculty of the Agricultural and Mechanical College of Texas in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Major...

Sanderson, Charles Frederick

2013-10-04

239

Oxidative Stress and Atrial Fibrillation  

Microsoft Academic Search

\\u000a The pathological processes involved in initiation and perpetuation of atrial fibrillation (AF) are still unclear. AF is associated\\u000a with systemic and cardiac oxidative stress and inflammation. Many risk factors for AF, such as aging and diabetes, are associated\\u000a with an increased level of reactive oxygen species. In addition, oxidative stress has been shown at both cellular and tissue\\u000a levels to

Ali A. Sovari; Samuel C. Dudley

240

Cadmium stress: an oxidative challenge  

Microsoft Academic Search

At the cellular level, cadmium (Cd) induces both damaging and repair processes in which the cellular redox status plays a\\u000a crucial role. Being not redox-active, Cd is unable to generate reactive oxygen species (ROS) directly, but Cd-induced oxidative\\u000a stress is a common phenomenon observed in multiple studies. The current review gives an overview on Cd-induced ROS production\\u000a and anti-oxidative defense

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

2010-01-01

241

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

242

Metal oxide nanostructures with hierarchical morphology  

DOEpatents

The present invention relates generally to metal oxide materials with varied symmetrical nanostructure morphologies. In particular, the present invention provides metal oxide materials comprising one or more metallic oxides with three-dimensionally ordered nanostructural morphologies, including hierarchical morphologies. The present invention also provides methods for producing such metal oxide materials.

Ren, Zhifeng (Newton, MA); Lao, Jing Yu (Saline, MI); Banerjee, Debasish (Ann Arbor, MI)

2007-11-13

243

Thin film hydrous metal oxide catalysts  

DOEpatents

Thin film (<100 nm) hydrous metal oxide catalysts are prepared by 1) synthesis of a hydrous metal oxide, 2) deposition of the hydrous metal oxide upon an inert support surface, 3) ion exchange with catalytically active metals, and 4) activating the hydrous metal oxide catalysts.

Dosch, Robert G. (Albuquerque, NM); Stephens, Howard P. (Albuquerque, NM)

1995-01-01

244

Passive Sampling of Atmospheric Photochemical Oxidants  

Microsoft Academic Search

A simple, cost-effective passive sampler is described that is suitable for measuring parts per billion (ppb) levels of photochemical oxidants (ozone + nitrogen dioxide + peroxyacetyl nitrate + peroxypropionyl nitrate) in ambient air. The passive sampler makes use of oxidant-fugitive colorants, and color changes are proportional to the oxidant dose, i.e. the product of oxidant concentration and sampling duration. Field

D. Grosjean; E. L. Williams Ii; E. Grosjean

1992-01-01

245

Nitroxide-Functionalized Graphene Oxide from Graphite Oxide  

PubMed Central

A facile method for preparing functionalized graphene oxide single layers with nitroxide groups is reported herein. Highly oxidized graphite oxide (GO=90.6%) was obtained, slightly modifying an improved Hummer’s method. Oxoammonium salts (OS) were investigated to introduce nitroxide groups to GO, resulting in a one-step functionalization and exfoliation. The mechanisms of functionalization/exfoliation are proposed, where the oxidation of aromatic alcohols to ketone groups, and the formation of alkoxyamine species are suggested. Two kinds of functionalized graphene oxide layers (GOFT1 and GOFT2) were obtained by controlling the amount of OS added. GOFT1 and GOFT2 exhibited a high interlayer spacing (d0001 = 1.12nm), which was determined by X-ray diffraction. The presence of new chemical bonds C-N (~9.5 %) and O-O (~4.3 %) from nitroxide attached onto graphene layers were observed by X-ray photoelectron spectroscopy. Single-layers of GOFT1 were observed by HRTEM, exhibiting amorphous and crystalline zones at a 50:50 ratio; in contrast, layers of GOFT2 exhibited a fully amorphous surface. Fingerprint of GOFT1 single layers was obtained by electron diffraction at several tilts. Finally, the potential use of these materials within Nylon 6 matrices was investigated, where an unusual simultaneous increase in tensile stress, tensile strain and Young’s modulus was observed. PMID:24347671

Avila-Vega, Yazmin I.; Leyva-Porras, Cesar C.; Mireles, Marcela; Quevedo-López, Manuel; Macossay, Javier; Bonilla-Cruz, José

2013-01-01

246

Catalytic effects of uranium oxides and salts in carbon oxidation  

SciTech Connect

The gasification reactions of carbon belong to an unusual class of heterogeneous processes involving the conversion of a solid phase into gaseous products. These reactions, which are of great technological importance, are catalyzed by many diverse types of inorganic species. In fact, active catalysts for carbon oxidation include members of every group in the Periodic Table. Although the detailed mechanism of few of these catalytic reactions have been unequivocally determined, it is generally agreed that cyclic redox processes on the carbon surface are probably the basis for the catalytic behavior. The metal uranium, which forms a complex series of interconvertible oxides, has apparently not hitherto been investigated as a catalyst for carbon oxidation and hence would provide a useful test for the redox mechanism. Uranium is found as a minor element in many coals, so that an understanding of its catalytic behavior during coal combustion would be of technological interest. This note describes the results of a study of the behavior of series of uranium oxides and uranyl salts as catalysts for the oxidation of graphite in the temperature range 500-1000/sup 0/C. 15 references.

McKee, D.W.

1986-01-01

247

Geophys. J. Int. (2002) 150, 230240 Iron oxide formation in the active oxidation front  

E-print Network

Geophys. J. Int. (2002) 150, 230­240 Iron oxide formation in the active oxidation front above sapropel (S1). The upper half of sapropel S1 has been oxidized, and Fe oxides have precipitated in the oxidized sapropel. Zero-field- cooling (ZFC) and field-cooling (FC) saturation remanent magnetization (Mr

Utrecht, Universiteit

248

Additive and Competitive Effects of Bacteria and Mn Oxides on Arsenite Oxidation Kinetics  

E-print Network

Additive and Competitive Effects of Bacteria and Mn Oxides on Arsenite Oxidation Kinetics L whose toxicity and mobility in soil depend on oxidation state. Arsenite [As(III)] can be oxidized and biotic processes is not well understood. In this study, the time dependency of As(III) oxidation by two

Sparks, Donald L.

249

Enhanced colonic nitric oxide generation and nitric oxide synthase activity in ulcerative colitis and Crohn's disease  

Microsoft Academic Search

Recent studies have suggested that nitric oxide (NO.), the product of nitric oxide synthase in inflammatory cells, may play a part in tissue injury and inflammation through its oxidative metabolism. In this study the colonic generation of oxides of nitrogen (NOx) and nitric oxide synthase activity was determined in ulcerative colitis and Crohn's disease. Colonic biopsy specimens were obtained from

D Rachmilewitz; J S Stamler; D Bachwich; F Karmeli; Z Ackerman; D K Podolsky

1995-01-01

250

Volatilization of oxides during oxidation of some superalloys at 1200°C  

Microsoft Academic Search

Volatilization of oxides during cyclic oxidation of commercial Nichrome, Inconel 750, René 41, Stellite 6B, and GE-1541 was studied at 1200°C in static air. Quantitative analysis of oxide vapor deposits revealed that oxides of tungsten, molybdenum, niobium, manganese, and chromium volatilized preferentially from the oxide scales. Aluminum and silicon were not detected in vapor deposits. For all the alloys except

Isidor Zaplatynsky

1977-01-01

251

Volatilization of oxides during oxidation of some superalloys at 1200 C. [Inconel 750, GE1531  

Microsoft Academic Search

Volatilization of oxides during cyclic oxidation of commercial Nichrome, Inconel 750, Rene 41, Stellite 6B, and GE-1541 was studied at 1200 C in static air. Quantitative analysis of oxide vapor deposits revealed that oxides of tungsten, molybdenum, niobium, manganese, and chromium volatilized preferentially from the oxide scales. Aluminum and silicon were not detected in vapor deposits. For all the alloys

Zaplatynsky

1977-01-01

252

On the partial oxidation of propane and propylene on mixed metal oxide catalysts  

Microsoft Academic Search

The present review analyses the literature data reported on the partial oxidation of propane to organic compounds (acrolein, acrylic acid and acrylonitrile) over mixed metal oxides, mainly magnesium vanadates, vanadia bismuth molybdates and vanadia antimony. The data were compared to those reported on the partial oxidation of propylene over bismuth molybdate and antimony—tin multicomponent oxides and over cuprous simple oxide.

M. M. Bettahar; G. Costentin; L. Savary; J. C. Lavalley

1996-01-01

253

Process for fabrication of metal oxide films  

SciTech Connect

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

254

EDITORIAL: Oxide semiconductors  

NASA Astrophysics Data System (ADS)

Blue or ultraviolet semiconducting light-emitting diodes have the potential to revolutionize illumination systems in the near-future. Such industrial need has propelled the investigation of several wide-gap semiconducting materials in recent years. Commercial applications include blue lasers for DVD memory and laser printers, while military applications are also expected. Most of the material development has so far been focused on GaN (band gap 3.5 eV at 2 K), and ZnSe (2.9 eV) because these two representative direct transition semiconductors are known to be bright emitting sources. GaN and GaN-based alloys are emerging as the winners in this field because ZnSe is subject to defect formation under high current drive. On the other hand, another II-VI compound, ZnO, has also excited substantial interest in the optoelectronics-oriented research communities because it is the brightest emitter of all, owing to the fact that its excitons have a 60 meV binding energy. This is compared with 26 meV for GaN and 20 meV for ZnSe. The stable excitons could lead to laser action based on their recombination even at temperatures well above room temperature. ZnO has additional major properties that are more advantageous than other wide-gap materials: availability of large area substrates, higher energy radiation stability, environmentally-friendly ingredients, and amenability to wet chemical etching. However, ZnO is not new to the semiconductor field as exemplified by several studies made during the 1960s on structural, vibrational, optical and electrical properties (Mollwo E 1982 Landolt-Boernstein New Series vol 17 (Berlin: Springer) p 35). In terms of devices, the luminescence from light-emitting diode structures was demonstrated in which Cu2O was used as the p-type material (Drapak I T 1968 Semiconductors 2 624). The main obstacle to the development of ZnO has been the lack of reproducible p-type ZnO. The possibility of achieving epitaxial p-type layers with the aid of thermal non-equilibrium growth has rekindled the recent extensive investigation and progress in the field of ZnO epitaxy. In this special issue, Ohtomo and Tsukazaki, Cho et al, and Yi et al, respectively, describe the various fabrication processes such as pulsed laser deposition, molecular-beam epitaxy and metal-organic chemical vapour deposition. It should be noted that the last work among the above-mentioned papers has the potential to pave the way to nano-technology based on ZnO. This material has found other important applications as well, such as transparent conducting oxides (TCO). This field has a long research history, as is reviewed by Minami. Relatively speaking, ZnO was one of the earliest crystals (after Si, Ge, and InSb) to be prepared in a pure form, and the resultant long research history has given rise to the availability of large-area substrates. Recent progress in this topic is explained by two representative groups of authors in this field: Nause and Nemeth at Cermet Inc., and Maeda et al at Tokyo Denpa Co. Ltd. In order to overcome the bottleneck of p-type conduction and control the material's properties, a clear understanding of the physical processes in ZnO is necessary. Look et al are known as the first group to report on the growth and properties of p-type ZnO layers with a valid and reasonable set of experimental data (2002 Appl. Phys. Lett. 81 1830). Here, Look contributes a more comprehensive review to this issue. Optical studies on single crystals were conducted and are reviewed here by Meyer et al and Chichibu et al. Band-gap engineering and fabrication of heterojunction or quantum structures are important technological issues. It should be emphasized that by choosing an appropriate set of concentrations (x and y), perfect lattice-matching between MgxZn1-xO and CdyZn1-yO can be attained (Makino T et al 2001 Appl. Phys. Lett. 78 1237). Exciton properties of multiple quantum well structures are reported by Makino et al in this issue. Other than growth of p-type layers, ferromagnetic behaviour in transition-metal doped oxide is also fuelling

Kawasaki, M.; Makino, T.

2005-04-01

255

Nitric oxide and oxidative stress in cardiovascular aging.  

PubMed

The long-standing free radical theory of aging, which attributes cellular pathology to the relentless accumulation of reactive oxygen species (ROS), remains attractive but controversial. Emerging insights into the molecular interactions between ROS and reactive nitrogen species (RNS) such as nitric oxide suggest that, in biological systems, one effect of increased ROS is the disruption of protein S-nitrosylation, a ubiquitous posttranslational modification system. In this way, ROS may not only damage cells but also disrupt widespread signaling pathways. Here, we discuss this phenomenon in the context of the cardiovascular system and propose that ideas regarding oxidative stress and aging need to be reevaluated to take account of the balance between oxidative and nitrosative stress. PMID:15917507

Raju, Shubha V Y; Barouch, Lili A; Hare, Joshua M

2005-05-25

256

Large-scale oxide nanostructures grown by thermal oxidation  

NASA Astrophysics Data System (ADS)

Large scale oxide nanostructures of CuO, Fe2O3, Co3O4, ZnO, etc. were prepared by catalyst-free thermal oxidation process in atmosphere using pure metal as the starting material. Various single crystalline nanostructure arrays, including nanowires, nanobelts, nononeedles, nanoflakes, and nanowalls were obtained. These nanostructures can be grown from bulk materials, like foils or sheet, or from the microsized metal powders and the pre-deposited metal film. The growth time, temperature and substrate have important effects on the morphology, size and distribution of the nanostructures. Different from V-S or V-L-S mechanisms, the growth of nanostructure is found to be based on the metal ion diffusion process. The gradual oxidation process of the metals was clearly demonstrated. The properties of these nanostructures including gas sensing, magnetism, photoluminescence, and field emission were extensively investigated.

Liu, Z. W.; Zhong, M. L.; Tang, C. M.

2014-06-01

257

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

258

Oxidation of commercial purity titanium  

NASA Technical Reports Server (NTRS)

The oxidation kinetics of commercial purity Ti-A55 exposed to laboratory air in the 593-760 C temperature range were continuously monitored by thermogravimetric analysis. The oxide thickness was measured by microscopy, and the substrate contamination was estimated from microhardness measurements. The microhardness depth profiles were converted to oxygen composition profiles using calibration depth. The oxygen diffusion coefficient in alpha-Ti appears to be approximately concentration-independent in the 1-10 at. pct oxygen range. Diffusion coefficient for oxygen in TiO2 has been estimated as a function of temperature and is found to be about 50 times the value in alpha-Ti. The metallographically prepared cross sections of the oxidized specimens revealed a 'moving boundary' in the substrate, parallel to the oxide-metal interface. This boundary was associated with a specific oxygen level of 5.0 + or - 0.5 at. pct. It occurred at a distance from the oxide-metal interface which was correlatable with temperature and time of exposure. The diffusion coefficient corresponding to the composition of this moving boundary is in excellent agreement with the effective diffusion coefficient for the substrate contamination.

Unnam, J.; Shenoy, R. N.; Clark, R. K.

1986-01-01

259

Space flight and oxidative stress  

NASA Technical Reports Server (NTRS)

Space flight is associated with an increase in oxidative stress after return to 1g. The effect is more pronounced after long-duration space flight. The effects lasts for several weeks after landing. In humans there is increased lipid peroxidation in erythrocyte membranes, reduction in some blood antioxidants, and increased urinary excretion of 8-iso-prostaglandin F(2alpha) and 8-oxo-7,8 dihydro-2 deoxyguanosine. Isoprostane 8-iso-prostaglandin F(2alpha) and 8-oxo-7,8 dihydro-2 deoxyguanosine are markers for oxidative damage to lipids and DNA, respectively. The changes have been attributed to a combination of the energy deficiency that occurs during flight and substrate competition for amino acids occurring between repleting muscle and other tissues during the recovery phase. The observations in humans have been complemented by rodent studies. Most rodent studies showed increased production of lipid peroxidation products postflight and decreased antioxidant enzyme activity postflight. The rodent observations were attributed to the stress associated with reentry into Earth's gravity. Decreasing the imbalance between the production of endogenous oxidant defenses and oxidant production by increasing the supply of dietary antioxidants may lessen the severity of the postflight increase in oxidative stress.

Stein, T. P.

2002-01-01

260

Integrating functional oxides with graphene  

NASA Astrophysics Data System (ADS)

Graphene-oxide hybrid structures offer the opportunity to combine the versatile functionalities of oxides with the excellent electronic transport in graphene. Understanding and controlling how the dielectric environment affects the intrinsic properties of graphene is also critical to fundamental studies and technological development of graphene. Here we review our recent effort on understanding the transport properties of graphene interfaced with ferroelectric Pb(Zr,Ti)O3 (PZT) and high-? HfO2. Graphene field effect devices prepared on high-quality single crystal PZT substrates exhibit up to tenfold increases in mobility compared to SiO2-gated devices. An unusual and robust resistance hysteresis is observed in these samples, which is attributed to the complex surface chemistry of the ferroelectric. Surface polar optical phonons of oxides in graphene transistors play an important role in the device performance. We review their effects on mobility and the high source-drain bias saturation current of graphene, which are crucial for developing graphene-based room temperature high-speed amplifiers. Oxides also introduce scattering sources that limit the low temperature electron mobility in graphene. We present a comprehensive study of the transport and quantum scattering times to differentiate various scattering scenarios and quantitatively evaluate the density and distribution of charged impurities and the effect of dielectric screening. Our results can facilitate the design of multifunctional nano-devices utilizing graphene-oxide hybrid structures.

Hong, X.; Zou, K.; DaSilva, A. M.; Ahn, C. H.; Zhu, J.

2012-08-01

261

Oxidative stress and leaf senescence  

PubMed Central

Background Senescence is an important developmental process that leads to the cell death through highly regulated genetically controlled processes in plants. Biotic and abiotic Oxidative stresses can also artificially induce senescence and increase the production of reactive oxygen species (ROS) specifically in chloroplast. One of the important oxidative stresses is paraquat that induces deviation of electron from photosynthesis electron chain and lead to the production of more ROS in chloroplast. Plants have evolved special adoptive mechanism to reallocate nutrient to reproductive and juvenile organs in senescence and different oxidative stresses. Rubisco seems to be the most abundant protein in plants and is involved in many changes during senescence. Results In the present study, the effects of ROS on Rubisco during senescence and oxidative stresses were evaluated by measuring photosynthesis factors such as net photosynthesis rate (Pn), stomatal conductance (G), evaporation rate (E), intra cellular CO2 concentration (Ci), fluorescence and total protein during three stages of development. Our results showed that in paraquat treated plants, CO2 assimilation is the most effective factor that refers to Rubisco damages. The highest correlation and regression coefficient belonged to Ci, while correlation coefficient between photosynthesis rate and total protein was much smaller. Conclusion It appears in the early stage of oxidative stresses such as exposing to paraquat, ROS has the most effect on Rubisco activity that induces more susceptibility to Rubisco specific protease. Moreover, Rubisco deactivation acts as an initiative signal for Rubisco degradation. PMID:22047555

2011-01-01

262

Tryptophan oxidation photosensitized by pterin.  

PubMed

Pterins are normal components of cells and they have been previously identified as good photosensitizers under UV-A irradiation, inducing DNA damage and oxidation of nucleotides. In this work, we have investigated the ability of pterin (Ptr), the parent compound of oxidized pterins, to photosensitize the oxidation of another class of biomolecules, amino acids, using tryptophan (Trp) as a model compound. Irradiation of Ptr in the UV-A spectral range (350 nm) in aerated aqueous solutions containing Trp led to the consumption of the latter, whereas the Ptr concentration remained unchanged. Concomitantly, hydrogen peroxide (H?O?) was produced. Although Ptr is a singlet oxygen ((1)O?) sensitizer, the degradation of Trp was inhibited in O?-saturated solutions, indicating that a (1)O?-mediated process (type II oxidation) was not an important pathway leading to Trp oxidation. By combining different analytical techniques, we could establish that a type I photooxidation was the prevailing mechanism, initiated by an electron transfer from the Trp molecule to the Ptr triplet excited state, yielding the corresponding radical ions (Trp(·+)/Trp(-H)· and Ptr(·-)). The Trp reaction products that could be identified by UPLC-mass spectrometry are in agreement with this conclusion. PMID:23747929

Thomas, Andrés H; Serrano, Mariana P; Rahal, Virginie; Vicendo, Patricia; Claparols, Catherine; Oliveros, Esther; Lorente, Carolina

2013-10-01

263

In situ reduction and oxidation of nickel from solid oxide fuel cells in a Titan ETEM  

E-print Network

In situ reduction and oxidation of nickel from solid oxide fuel cells in a Titan ETEM A. Faes1. The in situ reduction and re-oxidation of the FIB prepared TEM lamellae is performed in a FEI Titan equipped

Dunin-Borkowski, Rafal E.

264

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...

265

A survey of mercury in the Gulf of Mexico  

E-print Network

of mercury yield from wet oxidation of compound A with 5 g of persulfate and acidified with 10 ml concentrated HC1 . ~ ~ ~ 2$ Treatment and results obtained from EPA standards containing both organic and inor- ganic forms of mercury Summary of the best...'ced above. 23 ~Pre ra i o Natural W~te The water collected and stored as described on pages 8 and 11, respectively was unstoppered for the first time, and to each sample bottle was added 5 g of potassium persulfate (K28208) ~ The bottles were...

Custodi, George Louis

2012-06-07

266

Asymmetric vanadium catalyzed sulfide oxidation  

SciTech Connect

A vanadium based catalyst for the enantioselective sulfide oxidation was developed. In a very convenient procedure sulfides 1 can be enantioselectively oxidized to the corresponding optically active sulfoxides 2 with less than 0.1 mol% catalyst and hydrogen peroxide as oxygen source. The structure of ligand 3 was varied and special characteristics of the catalyst system were investigated. An important factor for good asymmetric induction is the primary hydroxyl group in 3. With other donors at this position, such as NHCOR, NHTs or carboxylate, racemic sulfoxides or products with moderate enantioselectivities were obtained. Another interesting feature is the ligand accelerated catalysis observed in this reaction. The current state of development and results of the oxidation of various substrates will be presented.

Bienewald, F.; Bolm, C. [Univ. of Marburg (Germany)

1995-12-31

267

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

268

Cellulose degradation by oxidative enzymes  

PubMed Central

Enzymatic degradation of plant biomass has attracted intensive research interest for the production of economically viable biofuels. Here we present an overview of the recent findings on biocatalysts implicated in the oxidative cleavage of cellulose, including polysaccharide monooxygenases (PMOs or LPMOs which stands for lytic PMOs), cellobiose dehydrogenases (CDHs) and members of carbohydrate-binding module family 33 (CBM33). PMOs, a novel class of enzymes previously termed GH61s, boost the efficiency of common cellulases resulting in increased hydrolysis yields while lowering the protein loading needed. They act on the crystalline part of cellulose by generating oxidized and non-oxidized chain ends. An external electron donor is required for boosting the activity of PMOs. We discuss recent findings concerning their mechanism of action and identify issues and questions to be addressed in the future. PMID:24688656

Dimarogona, Maria; Topakas, Evangelos; Christakopoulos, Paul

2012-01-01

269

Silicon oxidation in fluoride solutions  

NASA Technical Reports Server (NTRS)

Silicon is produced in a NaF, Na2SiF6, and Na matrix when SiF4 is reduced by metallic sodium. Hydrogen is evolved during acid leaching to separate the silicon from the accompanying reaction products, NaF and Na2SiF6. The hydrogen evolution reaction was studied under conditions simulating leaching conditions by making suspensions of the dry silicon powder in aqueous fluoride solutions. The mechanism for the hydrogen evolution is discussed in terms of spontaneous oxidation of silicon resulting from the cooperative effects of (1) elemental sodium in the silicon that reacts with water to remove a protective silica layer, leaving clean reactive silicon, and (2) fluoride in solution that complexes with the oxidized silicon in solution and retards formation of a protective hydrous oxide gel.

Sancier, K. M.; Kapur, V.

1980-01-01

270

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

271

Aromatic-radical oxidation kinetics  

SciTech Connect

Research progress in three areas is described. Progress achieved in the extensive experimental investigation of the oxidation and pyrolysis of cyclopentadiene is summarized first. The mechanistic implications of the experimental work are also discussed. An overview is given of the successful research effort devoted to modelling flow reactor toluene and benzene oxidation data. As mentioned above, one of the ultimate goals of this research is to develop a comprehensive, detailed chemical kinetic model of aromatics oxidation. The success already achieved in this effort augurs well for reaching the broader goal. The toluene/benzene model, however, does have a number of shortcomings which suggest the need for further experiments. A description is given of attempts to predict the laminar flame speeds of toluene and benzene. The difficulties encountered and the solutions found highlight the need of an examination of certain chemical steps that impact most the energy release of a burning aromatic fuel.

Not Available

1992-01-01

272

Initial oxidation of polycrystalline Permalloy surface  

NASA Astrophysics Data System (ADS)

X-ray photoelectron spectroscopy (XPS) and work-function measurements were used in combination to investigate the initial steps of Permalloy (Ni 80Fe 20) oxidation at room temperature. They showed that, after oxygen saturation, the surface is covered by nickel oxide (NiO), nickel hydroxide (Ni(OH) 2) and iron oxides (Fe xO y), and there is no preferential oxidation. Iron oxidation proceeds through the formation of FeO (Fe 2+) followed with Fe 2O 3 growth (Fe 3+). The oxidation is governed by a dissociative Langmuir-type oxidation: the sticking coefficient is decreasing over oxygen exposure. Oxidation continues by oxygen dissolution into the first layers to form a nano-oxide of about 8 Å in thickness.

Salou, M.; Lescop, B.; Rioual, S.; Lebon, A.; Youssef, J. Ben; Rouvellou, B.

2008-09-01

273

Catalyst for Oxidation of Volatile Organic Compounds  

NASA Technical Reports Server (NTRS)

Disclosed is a process for oxidizing volatile organic compounds to carbon dioxide and water with the minimal addition of energy. A mixture of the volatile organic compound and an oxidizing agent (e.g. ambient air containing the volatile organic compound) is exposed to a catalyst which includes a noble metal dispersed on a metal oxide which possesses more than one oxidation state. Especially good results are obtained when the noble metal is platinum, and the metal oxide which possesses more than one oxidation state is tin oxide. A promoter (i.e., a small amount of an oxide of a transition series metal) may be used in association with the tin oxide to provide very beneficial results.

Wood, George M. (Inventor); Upchurch, Billy T. (Inventor); Schryer, David R. (Inventor); Davis, Patricia P. (Inventor); Kielin, Erik J. (Inventor); Brown, Kenneth G. (Inventor); Schyryer, Jacqueline L. (Inventor); DAmbrosia, Christine M. (Inventor)

2000-01-01

274

Synthesis and Applications of Mixed Oxide Nanotubes  

NASA Astrophysics Data System (ADS)

Metal oxide nanotube is one of the nanostructured materials. Templates method, which is the technique in which templates are covered with metal oxides and the templates were removed to form metal oxide nanotubes, is a typical synthesis method for metal oxide nanotubes. In this section, synthesis of mixed oxide nanotubes using carbon nanofibers (CNFs) as templates is described. Because CNFs with various shapes were used as templates, oxide nanotubes with various shapes such as straight and helical were formed. Successive adsorption of metal oxide precursors on CNFs resulted in the formation of mixed oxide nanotubes with specific composition. In addition, a nano-macrostructured material, silica fiber-immobilized nanofibrous LaMnO3, was fabricated using this template process. In propane oxidation, the nano-macrostructured material showed superior activity to the conventional powder catalysts.

Ogihara, Hitoshi; Sadakane, Masahiro; Ueda, Wataru

275

?-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. PMID:20956542

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

2010-01-01

276

Photon-assisted oxidation and oxide thin film synthesis: A review  

Microsoft Academic Search

The article reviews an oxide materials synthesis approach utilizing photons. Photon-assisted oxide processing is an interesting and unique approach to synthesize ultra-thin oxides at relatively low temperatures. Photon-assisted oxidation can be implemented both during oxide synthesis as well as a post-deposition annealing step. The mechanisms governing photon-assisted oxygen incorporation into growing oxide films, namely, electric field and chemical effects are

Masaru Tsuchiya; Subramanian K. R. S. Sankaranarayanan; Shriram Ramanathan

2009-01-01

277

NDE Technologies for Ceramic Matrix Composites: Oxide and Non-Oxide  

Microsoft Academic Search

Ceramic matrix composites (CMCs) usually are classified into two materials systems: oxide- based and non-oxide-based. Oxide-based systems consist of an oxide fiber and an oxide matrix, whereas non-oxide systems can consist of carbon fibers with a carbon matrix (Carbon\\/Carbon), carbon fibers with a silicon carbide matrix (Carbon\\/SiC), as well as silicon carbide fibers with a silicon carbide matrix (SiC\\/SiC). In

J. G. Sun; C. M. Deemer; W. A. Ellingson; J. Wheeler

278

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 PMID:4977644

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

1969-01-01

279

Microbial oxidation of anabolic steroids.  

PubMed

Microbial transformation of two anabolic steroids, ethylestrenol (1) and nandrolone (2), were carried out. Ethylestrenol (1), when incubated with Rhizopus stolonifer (TSY 0471), yielded two oxidative metabolites named 17alpha-ethyl-3beta,17beta-dihydroxy-19-norndrost-4-ene (3) and 17alpha-ethyl-17beta-hydroxy-19-norandrost-4-en-3-one (4), while incubation of compound 2 with the same fungus yielded two oxidative metabolites, 19-norandrost-4-en-3,17-dione (5) and 6alpha,17beta-dihydroxy-19-norandrost-1,4-dien-3-one (6). PMID:19023784

Iqbal Choudhary, M; Adnan, S; Shah, A; Atta-Ur-Rahman

2008-01-01

280

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

281

Aromatic-radical oxidation chemistry  

SciTech Connect

The research effort has focussed on discovering an explanation for the anomalously high CO{sub 2} concentrations observed early in the reaction sequence of the oxidation of cyclopentadiene. To explain this observation, a number of plausible mechanisms have been developed which now await experimental verification. One experimental technique for verifying mechanisms is to probe the reacting system by perturbing the radical concentrations. Two forms of chemical perturbation of the oxidation of cyclopentadiene were begun during this past year--the addition of NO{sub 2} and CO to the reacting mixture.

Glassman, I.; Brezinsky, K. [Princeton Univ., NJ (United States)

1993-12-01

282

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, Robert (Churchill Boro, PA); George, Raymond A. (Pittsburgh, PA); Shockling, Larry A. (Plum Borough, PA)

1993-01-01

283

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

284

New layered manganese oxide halides.  

PubMed

The first layered manganese(III) oxide chlorides, Sr2MnO3Cl and Sr4Mn3O8-yCl2, have been synthesised; Sr2MnO3Cl adopts a K2NiF4 type structure with sheets of MnO5 square based pyramids linked through oxygen and separated by SrCl layers; it is the end member of a new family of Ruddlesden-Popper type manganese oxide halides which includes the three-layer member Sr4Mn3O8-yCl2 also reported herein. PMID:12120392

Knee, Christopher S; Weller, Mark T

2002-02-01

285

Hydrous metal oxide catalysts for oxidation of hydrocarbons  

SciTech Connect

This report describes work performed at Sandia under a CRADA with Shell Development of Houston, Texas aimed at developing hydrous metal oxide (HMO) catalysts for oxidation of hydrocarbons. Autoxidation as well as selective oxidation of 1-octene was studied in the presence of HMO catalysts based on known oxidation catalysts. The desired reactions were the conversion of olefin to epoxides, alcohols, and ketones, HMOs seem to inhibit autoxidation reactions, perhaps by reacting with peroxides or radicals. Attempts to use HMOs and metal loaded HMOs as epoxidation catalysts were unsuccessful, although their utility for this reaction was not entirely ruled out. Likewise, alcohol formation from olefins in the presence of HMO catalysts was not achieved. However, this work led to the discovery that acidified HMOs can lead to carbocation reactions of hydrocarbons such as cracking. An HMO catalyst containing Rh and Cu that promotes the reaction of {alpha}-olefins with oxygen to form methyl ketones was identified. Although the activity of the catalyst is relatively low and isomerization reactions of the olefin simultaneously occur, results indicate that these problems may be addressed by eliminating mass transfer limitations. Other suggestions for improving the catalyst are also made. 57 refs.

Miller, J.E.; Dosch, R.G.; McLaughlin, L.I. [Sandia National Labs., Albuquerque, NM (United States). Process Research Dept.

1993-07-01

286

Mechanism of the anodic oxidation of carbon by oxide melts  

NASA Astrophysics Data System (ADS)

The kinetics of anodic oxidation of carbon-containing materials in borosilicate melts is studied. A mechanism of the anodic process that takes into account the surface diffusion of adsorbed oxygen atoms is proposed. The kinetic characteristics of the process for various systems and experimental conditions are determined.

Rogachev, V. V.; Vatolin, A. N.

2012-08-01

287

Saltstone Oxidation Study: Leaching Method  

SciTech Connect

Cementitious waste forms can be designed to chemically stabilize selected contaminants, such as Tc{sup +7} and Cr{sup +6}, by chemically reduction to lower valance states, Tc{sup +4} and Cr{sup +3}, respectively, and precipitation of these species in alkaline media as low solubility solid phases. Data for oxidation of this type of cementitious waste form cured under field conditions as a function of time is required for predicting the performance of the waste form and disposal facility. The rate of oxidation (oxidation front advancement) is an important parameter for predicting performance because the solubilities of some radionuclide contaminants, e.g., technetium, are a function of the oxidation state. A non-radioactive experiment was designed for quantifying the oxidation front advancement using chromium, as an approximate redox-sensitive surrogate (Cr{sup +6} / Cr{sup +3}) for technetium (Tc{sup +7} / Tc{sup +4}). Nonradioactive cementitious waste forms were prepared in the laboratory and cured under both laboratory and ?field conditions.? Laboratory conditions were ambient temperature and sealed sample containers. Field conditions were approximated by curing samples in open containers which were placed inside a plastic container stored outdoors at SRS. The container had a lid and was instrumented with temperature and humidity probes. Subsamples as thin as 0.2 mm were taken as a function of distance from the exposed surface of the as-cast sample. The subsamples were leached and the leachates were analyzed for chromium, nitrate, nitrite and sodium. Nitrate, nitrite, and sodium concentrations were used to provide baseline data because these species are not chemically retained in the waste form matrix to any significant extent and are not redox sensitive. ?Effective? oxidation fronts for Cr were measured for samples containing 1000, 500 and 20 mg/kg Cr added as soluble sodium chromate, Na{sub 2}CrO{sub 4}. For a sample cured for 129 days under field conditions, leachable Cr (assumed to be the oxidized form, i.e., Cr{sup +6} was detected in the top 15 to 20 mm of the sample spiked with 1000 mg/kg Cr. Below about 20 mm, the Cr concentrations in leachates were below the detection limit (< 0.010 mg/L) which indicates that the oxidation as the result of exposure to air was limited to the top 20 mm of the sample after exposure for 129 days and that the bulk of the waste form was not affected, i.e., the Cr was stabilized and insoluble. For samples cured in the laboratory, leachable Cr was detected in the top 8 mm of the Cr 1000 sample cured in the laboratory for 37 days. Between 8 and 14 mm, the concentration Cr in the leachate dropped by a factor of about 20 to just above the detection limit. These depth of penetration results indicate that the rate of advancement of the oxidation front for samples spiked with 1000 mg/kg Cr cured under ?field conditions? for 129 days is less than that for the sample cured in the laboratory for 37 days, i.e., 0.156 and 0.216 mm/day, respectively. Additional data are presented for samples spiked with 500 and 20 mg/kg Cr. In summary, cementitious waste forms are porous solids with a network of interconnected pores ranging in diameter from 10E-10 m to greater than a few mm. The oxidation process is assumed to occur as the result of oxygen transport through the interconnected porosity which may be filled with air, aqueous salt solution, or both. Upon oxidation, the Cr becomes soluble and can be transported in solution through aqueous pore fluid or leachate.

Langton, C. A.; Stefanko, D. B.; Burns, H. H.

2013-02-24

288

Oxidative removal of aqueous steroid estrogens by manganese oxides.  

PubMed

This study investigated the oxidative removal of steroid estrogens from water by synthetic manganese oxide (MnO2) and the factors influencing the reactions. Using 1 x 10(-5)M MnO2 at pH 4, estrone (E1), 17beta-estradiol (E2), estriol (E3) and 17alpha-ethinylestradiol (EE2), all at 4 x 10(-6)M, were rapidly removed within 220 min, indicating the effectiveness of MnO2 as an oxidizing agent towards estrogens. E2 removal increased with decreasing pH over the tested range of 4-8, due most likely to increased oxidizing power of MnO2 and a cleaner reactive surface in acidic solutions. Coexisting metal ions of 0.01 M (Cu(II), Zn(II), Fe(III) and Mn(II)) and Mn(II) released from MnO2 reduction competed with E2 for reactive sites leading to reduced E2 removal. Observed differential suppression on E2 removal may be related to different speciations of metals, as suggested by the MINTEQ calculations, and hence their different adsorptivities on MnO2. By suppressing the metal effect, humic acid substantially enhanced E2 removal. This was attributed to complexation of humic acid with metal ions. With 0.01 M ZnCl2 in solutions containing 1 mg l(-1) humic acid, the binding of humic acid for Zn(II) was determined at 251 mmol g(-1). An in vitro assay using human breast carcinoma MCF-7 cells indicated a near elimination of estrogenic activities without secondary risk of estrogen solutions treated with MnO2. Synthetic MnO2 is therefore a promising chemical agent under optimized conditions for estrogen removal from water. Metal chelators recalcitrant to MnO2 oxidation may be properly used to further enhance the MnO2 performance. PMID:18929389

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

2008-12-01

289

Production of oceanic nitrous oxide by ammonia-oxidizing archaea  

NASA Astrophysics Data System (ADS)

The recent finding that microbial ammonia oxidation in the ocean is performed by archaea to a greater extent than by bacteria has drastically changed the view on oceanic nitrification. The numerical dominance of archaeal ammonia-oxidizers (AOA) over their bacterial counterparts (AOB) in large parts of the ocean leads to the hypothesis that AOA rather than AOB could be the key organisms for the oceanic production of the strong greenhouse gas nitrous oxide (N2O) which occurs as a by-product of nitrification. Very recently, enrichment cultures of marine ammonia-oxidizing archaea have been described to produce N2O. Here, we demonstrate that archaeal ammonia monooxygenase genes (amoA) were detectable throughout the water column of the Eastern Tropical North Atlantic (ETNA) and Eastern Tropical South Pacific Oceans (ETSP). Particularly in the ETNA, maxima in abundance and expression of archaeal amoA genes correlated with the N2O maximum and the oxygen minimum, whereas the abundances of bacterial amoA genes were negligible. Moreover, selective inhibition of archaea in seawater incubations from the ETNA decreased the N2O production significantly. In studies with the only cultivated marine archaeal ammonia-oxidizer Nitrosopumilus maritimus SCM1, we provide the first direct evidence for N2O production in a pure culture of AOA, excluding the involvement of other microorganisms as possibly present in enrichments. N. maritimus showed high N2O production rates under low oxygen concentrations comparable to concentrations existing in the oxycline of the ETNA, whereas the N2O production from two AOB cultures was comparably low under similar conditions. Based on our findings, we hypothesize that the production of N2O in tropical ocean areas results mainly from archaeal nitrification and will be affected by the predicted decrease in dissolved oxygen in the ocean.

Loescher, C. R.; Kock, A.; Koenneke, M.; Laroche, J.; Bange, H. W.; Schmitz, R. A.

2012-02-01

290

NATURAL EMISSIONS OF OXIDANT PRECURSORS  

EPA Science Inventory

This paper provides an overview of the sources, the estimation methodology, and the relative amounts of natural hydrocarbon and nitrogen oxide emissions. he most recent estimate of natural nonmethane hydrocarbon (NMHC) emissions for the United States is 28 teragrams per year (Tg/...

291

Oxidation of basic lead sulfates  

Microsoft Academic Search

It cannot yet be claimed that the mechanism of forming of lead battery pastes, or the influence of various technological parameters on the kinetics of their oxidation have been established with certainty. Difficulties in interpretation of experimental results are due both to the indefinite nature of the principal structural characteristics of the pastes and to their multiphase character. The mechanism

Y. B. Kamenev; A. I. Rusin; Z. I. Zhivilova

1983-01-01

292

Oxidative stabilization of acrylic fibres  

Microsoft Academic Search

When acrylic fibres are heat treated for various times at 220 to 250° C, they form dark, insoluble structures of uncertain chemical character which are inert to many strong oxidizing and reducing agents. The heat-treated fibres are, however, rapidly decoloured by warm alkaline hypochlorite solutions. When fibres which have undergone short-time heat treatment are subjected to the hypochlorite, incubation periods

S. S. Chen; J. Herms; L. H. Peebles; D. R. Uhlmann

1981-01-01

293

Method of forming oxide coatings  

Microsoft Academic Search

This invention is concerned with an improved plating process for covering a substrate with a black metal oxide film. The invention is particularly directed to making a heating panel for a solar collector. A compound is electrodeposited from an aqueous solution containing cobalt metal salts onto a metal substrate. This compound is converted during plating into a black, highly absorbing

1981-01-01

294

Oxidative stress, AGE, and atherosclerosis  

Microsoft Academic Search

Numerous reports on the molecular mechanism of atherogenesis indicate an increase in oxidative stress, formation of advanced glycoxidation end products (AGEs), chronic inflammation, and activated cellular response particularly in diabetic patients. To elucidate the initiating and early accelerating events this review will focus on the molecular causes of the induction of these stress factors, their interactions, and their contribution to

E Schleicher; U Friess

2007-01-01

295

Bacterial oxidation of gaseous alkanes  

Microsoft Academic Search

The pathways of oxidation of the normal aliphatic hydrocarbons in biological systems are at the moment mainly matters of conjecture. In a number of studies fatty acids have been found after growth of a microorganism in the culture medium in which an individual hydrocarbon was present as the sole source of carbon and energy. This has led to the assumption

E. R. Leadbetter; J. W. Foster

1960-01-01

296

Aromatic-radical oxidation chemistry  

SciTech Connect

There are anomalously high CO[sub 2] concentrations early in the reaction sequence in the oxidation of cyclopentadiene. A number of plausible mechanisms have been developed. NO[sub 2] and CO have been added to the reacting mixture, to assist in selecting the best mechanism. Effects of these chemical perturbations were studied.

Glassman, I.; Brezinsky, K.

1993-01-01

297

METHANE OXIDATION (AEROBIC) Helmut Brgmann  

E-print Network

(AEROBIC) 575 Eawag_06356 #12;respiration. Differences between methanotrophs are thought to exist regardingMETHANE OXIDATION (AEROBIC) Helmut Bürgmann Eawag, Swiss Federal Institute of Aquatic Science Chapter Aerobic Metabolism) via a pyrroloquinoline quinone cofactor to cytochrome C (methanol

Wehrli, Bernhard

298

Nitric oxide and cellular respiration  

Microsoft Academic Search

The role of nitric oxide (NO) as a signalling molecule involved in many pathophysiological processes (e.g., smooth muscle relaxation, inflammation, neurotransmission, apoptosis) has been elaborated during the last decade. Since NO has also been found to inhibit cellular respiration, we review here the available information on the interactions of NO with cytochrome c oxidase (COX), the terminal enzyme of the

M. Brunori; A. Giuffrè; P. Sarti; G. Stubauer; M. T. Wilson

1999-01-01

299

Pyroelectric properties of polyethylene oxide  

NASA Astrophysics Data System (ADS)

Transformations of the structure and changes in the polarization properties of polyethylene oxide are investigated in the crystallization region. It is demonstrated that the pyroelectric coefficient of this polymer is considerably higher than the corresponding parameter for polyvinylidene fluoride and is nearly equal to the pyroelectric coefficient for triglycine sulfate.

Korotkikh, N. I.; Matveev, N. N.; Sidorkin, A. S.

2009-06-01

300

Thermal Decomposition of Nitric Oxide  

Microsoft Academic Search

The decomposition of pure nitric oxide and of mixtures with nitrogen or helium was studied at T = 1170 to 1530°K in quartz vessels. Above about T = 1400°K, the reaction is homogeneous and cleanly second order in NO throughout the course of decomposition. A change in the surface to volume ratio leaves the rate unchanged as does the addition

Frederick Kaufman; John R. Kelso

1955-01-01

301

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

302

Nitric oxide: The wonder molecule  

Microsoft Academic Search

Nitric oxide, a newly discovered biological messenger molecule that is produced from different kinds of cells has diversified\\u000a and has significant effects on various pathological and physiological events ranging from the prevention of cancer and diabetes\\u000a mellitus to coronary artery disease (heart attack) and hypertension.

Kushal Chakraborty

2003-01-01

303

Machinable dissolved metal oxide superconductors  

SciTech Connect

Powders of a metal oxide superconductor are mixed with sufficient amount (10--80 mol%) of In, Sn, and/or Al, to become nonbrittle, machinable. Preferred superconductors are YBa[sub 2]Cu[sub 3]O[sub 7[minus]x] and Bi-Sr-Ca-Cu-O compounds.

Chen, Chung-Hsuan.

1991-01-01

304

Enzymatic oxidation of aqueous pentachlorophenol  

Microsoft Academic Search

The influence of the nonionic surfactant Tween 80 on pentachlorophenol (PCP) oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration (CMC). Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical

E. Y. Kim; H. J. Chae; K. H. Chu

2007-01-01

305

Oxidative Stress and Neurodegenerative Disorders  

PubMed Central

Living cells continually generate reactive oxygen species (ROS) through the respiratory chain during energetic metabolism. ROS at low or moderate concentration can play important physiological roles. However, an excessive amount of ROS under oxidative stress would be extremely deleterious. The central nervous system (CNS) is particularly vulnerable to oxidative stress due to its high oxygen consumption, weakly antioxidative systems and the terminal-differentiation characteristic of neurons. Thus, oxidative stress elicits various neurodegenerative diseases. In addition, chemotherapy could result in severe side effects on the CNS and peripheral nervous system (PNS) of cancer patients, and a growing body of evidence demonstrates the involvement of ROS in drug-induced neurotoxicities as well. Therefore, development of antioxidants as neuroprotective drugs is a potentially beneficial strategy for clinical therapy. In this review, we summarize the source, balance maintenance and physiologic functions of ROS, oxidative stress and its toxic mechanisms underlying a number of neurodegenerative diseases, and the possible involvement of ROS in chemotherapy-induced toxicity to the CNS and PNS. We ultimately assess the value for antioxidants as neuroprotective drugs and provide our comments on the unmet needs. PMID:24351827

Li, Jie; O, Wuliji; Li, Wei; Jiang, Zhi-Gang; Ghanbari, Hossein A.

2013-01-01

306

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

307

Nanostructured manganese oxide/carbon nanotubes, graphene and graphene oxide as water-oxidizing composites in artificial photosynthesis.  

PubMed

Herein, we report on nano-sized Mn oxide/carbon nanotubes, graphene and graphene oxide as water-oxidizing compounds in artificial photosynthesis. The composites are synthesized by different and simple procedures and characterized by a number of methods. The water-oxidizing activities of these composites are also considered in the presence of cerium(IV) ammonium nitrate. Some composites are efficient Mn-based catalysts with TOF (mmol O2 per mol Mn per second) ~ 2.6. PMID:24898625

Najafpour, Mohammad Mahdi; Rahimi, Fahime; Fathollahzadeh, Maryam; Haghighi, Behzad; Ho?y?ska, Ma?gorzata; Tomo, Tatsuya; Allakhverdiev, Suleyman I

2014-07-28

308

Oxidation kinetics of aluminum diboride  

SciTech Connect

The oxidation characteristics of aluminum diboride (AlB{sub 2}) and a physical mixture of its constituent elements (Al+2B) were studied in dry air and pure oxygen using thermal gravimetric analysis to obtain non-mechanistic kinetic parameters. Heating in air at a constant linear heating rate of 10 °C/min showed a marked difference between Al+2B and AlB{sub 2} in the onset of oxidation and final conversion fraction, with AlB{sub 2} beginning to oxidize at higher temperatures but reaching nearly complete conversion by 1500 °C. Kinetic parameters were obtained in both air and oxygen using a model-free isothermal method at temperatures between 500 and 1000 °C. Activation energies were found to decrease, in general, with increasing conversion for AlB{sub 2} and Al+2B in both air and oxygen. AlB{sub 2} exhibited O{sub 2}-pressure-independent oxidation behavior at low conversions, while the activation energies of Al+2B were higher in O{sub 2} than in air. Differences in the composition and morphology between oxidized Al+2B and AlB{sub 2} suggested that Al{sub 2}O{sub 3}–B{sub 2}O{sub 3} interactions slowed Al+2B oxidation by converting Al{sub 2}O{sub 3} on aluminum particles into a Al{sub 4}B{sub 2}O{sub 9} shell, while the same Al{sub 4}B{sub 2}O{sub 9} developed a needle-like morphology in AlB{sub 2} that reduced oxygen diffusion distances and increased conversion. The model-free kinetic analysis was critical for interpreting the complex, multistep oxidation behavior for which a single mechanism could not be assigned. At low temperatures, moisture increased the oxidation rate of Al+2B and AlB{sub 2}, but both appear to be resistant to oxidation in cool, dry environments. - Graphical abstract: Isothermal kinetic data for AlB{sub 2} in air, showing a constantly decreasing activation energy with increasing conversion. Model-free analysis allowed for the calculation of global kinetic parameters despite many simultaneous mechanisms occurring concurrently. (a) Time–temperature plots, (b) conversion as a function of time, (c) Arrhenius plots used to calculate activation energies, and (d) activation energy as a function of conversion. Display Omitted - Highlights: • First reported kinetic parameters for AlB{sub 2} and Al+2B oxidation in air and O{sub 2}. • Possible mechanism of enhanced boron combustion presented. • Moisture sensitivity shown to be problematic for AlB{sub 2}, less for Al+2B.

Whittaker, Michael L., E-mail: michaelwhittaker2016@u.northwestern.edu [Department of Materials Science and Engineering, University of Utah, 122S. Central Campus Drive, Salt Lake City, UT 84112 (United States); Sohn, H.Y. [Department of Metallurgical Engineering, University of Utah, 135S 1460 E, Rm 00412, Salt Lake City, UT 84112 (United States); Cutler, Raymond A. [Ceramatec, Inc., 2425S. 900W., Salt Lake City, UT 84119 (United States)

2013-11-15

309

21 CFR 177.1620 - Polyethylene, oxidized.  

...accordance with the following prescribed conditions: (a) Oxidized polyethylene is the basic resin produced by the mild air oxidation of polyethylene conforming to the density, maximum n- hexane extractable fraction, and maximum xylene soluble...

2014-04-01

310

ChemTeacher Resource: Oxidation Reduction Reactions  

NSDL National Science Digital Library

This computer resource goes over oxidation reduction reactions and how they are broken down into half reactions. It explains which half reaction is the oxidation reaction and which one is the reduction, then has some summary questions at the end.

Dr. Martin McClinton, Debbie McClinton, Dr. Miriam Douglass

2011-01-01

311

21 CFR 177.1620 - Polyethylene, oxidized.  

Code of Federal Regulations, 2012 CFR

...ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use Food Contact...conditions: (a) Oxidized polyethylene is the basic resin produced by the mild air oxidation of polyethylene conforming to the density,...

2012-04-01

312

21 CFR 177.1620 - Polyethylene, oxidized.  

Code of Federal Regulations, 2013 CFR

...ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use Food Contact...conditions: (a) Oxidized polyethylene is the basic resin produced by the mild air oxidation of polyethylene conforming to the density,...

2013-04-01

313

21 CFR 184.1210 - Calcium oxide.  

Code of Federal Regulations, 2013 CFR

...Substances Affirmed as GRAS § 184.1210 Calcium oxide. (a) Calcium oxide (CaO, CAS Reg. No. 1305-78-8...lime, burnt lime, or calx. It is produced from calcium carbonate, limestone, or oyster shells by...

2013-04-01

314

21 CFR 184.1210 - Calcium oxide.  

...Specific Substances Affirmed as GRAS § 184.1210 Calcium oxide. (a) Calcium oxide (CaO, CAS Reg. No. 1305-78-8...lime, burnt lime, or calx. It is produced from calcium carbonate, limestone, or oyster shells by...

2014-04-01

315

21 CFR 184.1210 - Calcium oxide.  

Code of Federal Regulations, 2010 CFR

...Substances Affirmed as GRAS § 184.1210 Calcium oxide. (a) Calcium oxide (CaO, CAS Reg. No. 1305-78-8...lime, burnt lime, or calx. It is produced from calcium carbonate, limestone, or oyster shells by...

2010-04-01

316

21 CFR 184.1210 - Calcium oxide.  

Code of Federal Regulations, 2011 CFR

...Substances Affirmed as GRAS § 184.1210 Calcium oxide. (a) Calcium oxide (CaO, CAS Reg. No. 1305-78-8...lime, burnt lime, or calx. It is produced from calcium carbonate, limestone, or oyster shells by...

2011-04-01

317

21 CFR 184.1210 - Calcium oxide.  

Code of Federal Regulations, 2012 CFR

...Substances Affirmed as GRAS § 184.1210 Calcium oxide. (a) Calcium oxide (CaO, CAS Reg. No. 1305-78-8...lime, burnt lime, or calx. It is produced from calcium carbonate, limestone, or oyster shells by...

2012-04-01

318

Genomic consequences of DNA oxidation by peroxynitrite  

E-print Network

The radicals nitric oxide and superoxide are produced endogenously by activated macrophages and neutrophils and combine in a diffusion-limited reaction to form peroxynitrite, a powerful oxidizing and nitrating agent capable ...

Neeley, William Louis

2006-01-01

319

Characterization of Rhenium Oxides Using ESCA  

NASA Technical Reports Server (NTRS)

High melting point and inherent ductility (toughness) over a wide range of temperature has made Rhenium an engineering material of choice for several thrust chambers in propulsion systems. Although the material remains tough at high temperatures, it still can readily transform to several oxides. As many as eight different oxides have been reported in literature. When characterized using ESCA (Electron Spectroscopy for Chemical Analyses) these oxides show large shifts in the Re 4f line positions. While this unique property could be used as a tool for oxide characterization, literature indicates that only a few of these oxides have been characterized. Current work focuses on characterizing oxides of Rhenium using ESCA. Spectral line Re 4f have been measured for various oxides and the results have been compared with the Re 4f line positions of real-time oxidation products from space hardware.

Panda, Binayak; Gentz, Steven J. (Technical Monitor)

2001-01-01

320

21 CFR 73.1991 - Zinc oxide.  

Code of Federal Regulations, 2012 CFR

...and suitable in color additive mixtures for coloring...be avoided by good manufacturing practice: Zinc oxide...restrictions. The color additive zinc oxide may be...consistent with good manufacturing practice. (d) Labeling. The color additive and any mixtues...

2012-04-01

321

21 CFR 73.1991 - Zinc oxide.  

...and suitable in color additive mixtures for coloring...be avoided by good manufacturing practice: Zinc oxide...restrictions. The color additive zinc oxide may be...consistent with good manufacturing practice. (d) Labeling. The color additive and any mixtues...

2014-04-01

322

21 CFR 73.1991 - Zinc oxide.  

Code of Federal Regulations, 2013 CFR

...and suitable in color additive mixtures for coloring...be avoided by good manufacturing practice: Zinc oxide...restrictions. The color additive zinc oxide may be...consistent with good manufacturing practice. (d) Labeling. The color additive and any mixtues...

2013-04-01

323

29 CFR 1926.1147 - Ethylene oxide.  

Code of Federal Regulations, 2010 CFR

29 Labor 8 2010-07-01 2010-07-01 false Ethylene oxide. 1926.1147 Section 1926.1147 Labor Regulations...CONSTRUCTION Toxic and Hazardous Substances § 1926.1147 Ethylene oxide. Note: The requirements applicable to...

2010-07-01

324

Electrolyte for Anodic Oxidation of Titanium Alloys.  

National Technical Information Service (NTIS)

The invention involves the electrolytic production of oxide films on titanium alloys which operate both under conditions of dry friction and with the use of lubricants. The purpose of the invention is to increase the antifriction properties of oxide films...

V. P. Batrakov, L. N. Pivovarova, A. S. Pivavorov, G. M. Elidkumson, V. V. Chukhin

1983-01-01

325

21 CFR 184.1545 - Nitrous oxide.  

...smell. It does not burn but will support combustion. Nitrous oxide is manufactured by the thermal decomposition of ammonium nitrate. Higher oxides of nitrogen are removed by passing the dry gas through a series of scrubbing towers. (b) The...

2014-04-01

326

49 CFR 173.323 - Ethylene oxide.  

Code of Federal Regulations, 2013 CFR

...used in ethylene oxide service. (e) In determining outage, consideration must be given to the lading temperature and solubility of inert gas padding in ethylene oxide as well as the partial pressure exerted by the gas padding. (f) Each tank,...

2013-10-01

327

49 CFR 173.323 - Ethylene oxide.  

Code of Federal Regulations, 2011 CFR

...used in ethylene oxide service. (e) In determining outage, consideration must be given to the lading temperature and solubility of inert gas padding in ethylene oxide as well as the partial pressure exerted by the gas padding. (f) Each tank,...

2011-10-01

328

49 CFR 173.323 - Ethylene oxide.  

Code of Federal Regulations, 2012 CFR

...used in ethylene oxide service. (e) In determining outage, consideration must be given to the lading temperature and solubility of inert gas padding in ethylene oxide as well as the partial pressure exerted by the gas padding. (f) Each tank,...

2012-10-01

329

Complex oxides useful for thermoelectric energy conversion  

DOEpatents

The invention provides for a thermoelectric system comprising a substrate comprising a first complex oxide, wherein the substrate is optionally embedded with a second complex oxide. The thermoelectric system can be used for thermoelectric power generation or thermoelectric cooling.

Majumdar, Arunava (Orinda, CA); Ramesh, Ramamoorthy (Moraga, CA); Yu, Choongho (College Station, TX); Scullin, Matthew L. (Berkeley, CA); Huijben, Mark (Enschede, NL)

2012-07-17

330

Oxidation of Terthiophene Substituted with Ferrocenyl Groups  

NASA Astrophysics Data System (ADS)

Terthiophenes substituted with ferrocenyl or methyl groups were prepared by a palladium-catalyzed cross-coupling reaction. The oxidation processes and the oxidized states of the compounds were investigated by cyclic voltammetry, coulometry, and electronic absorption spectroscopy. The first oxidation of the ferrocenyl-terthiophenes took place on the ferrocene moiety; the resultant oxidized states spread over the terthiophene moiety. This implies the charge transfer from the ferricinium ion moiety to the terthiophene moiety.

Sato, Masa-aki; Kashiwagi, Shin-ichiro; Taniguchi, Hiroyuki; Hiroi, Masao

1999-09-01

331

Fatigue oxidation interaction in in 100 superalloy  

Microsoft Academic Search

The interaction between fatigue and oxidation has been studied in IN 100,* a cast nickel based su-peralloy tested in laboratory\\u000a air at 1000 C. The effect of fatigue cycling on oxidation was studied by quantitative metallography on polished specimens\\u000a which were oxidized in a furnace and on strain cycled low cycle fatigue specimens. Thickness measurements have shown that\\u000a matrix oxidation

M. Reger; L. Rémy

1988-01-01

332

Electronic structure of graphene oxide and reduced graphene oxide monolayers  

SciTech Connect

Graphene oxide (GO) monolayers obtained by Langmuir Blodgett route and suitably treated to obtain reduced graphene oxide (RGO) monolayers were studied by photoelectron spectroscopy. Upon reduction of GO to form RGO C1s x-ray photoelectron spectra showed increase in graphitic carbon content, while ultraviolet photoelectron spectra showed increase in intensity corresponding to C2p-{pi} electrons ({approx}3.5 eV). X-ray excited Auger transitions C(KVV) and plasmon energy loss of C1s photoelectrons have been analyzed to elucidate the valence band structure. The effective number of ({pi}+{sigma}) electrons as obtained from energy loss spectra was found to increase by {approx}28% on reduction of GO.

Sutar, D. S. [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Central Surface Analytical Facility, Indian Institute of Technology Bombay, Mumbai 400076 (India); Singh, Gulbagh; Divakar Botcha, V. [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India)

2012-09-03

333

A Porphyrin-Stabilized Iridium Oxide Water Oxidation Catalyst  

SciTech Connect

Colloidal solutions of iridium oxide hydrate (IrO{sub 2}·NH{sub 2}O) were formed using porphyrin stabilizers bearing malonate-like functional groups at each of the four meso positions of the porphyrin ring. Cyclic voltammetry and monitoring of solution oxygen concentrations under constant applied potential demonstrated the electrochemical catalytic activity of the porphyrin–IrO{sub 2}·NH{sub 2}O complexes for the oxidation of water to oxygen. Quenching of the porphyrin fluorescence in the complex implies strong interaction between the porphyrin and the IrO{sub 2}·NH{sub 2}O. These results mark a step toward developing a porphyrin-based photoanode for use in a photoelectrochemical water-splitting cell.

Sherman, Ben; Pillai, Smitha; Kodis, Gerdenis; Bergkamp, Jesse; Mallouk, Thomas E.; Gust, Devens; Moore, Thomas A.; Moore, Ana L.

2011-01-01

334

Nano-structuring of complex metal oxides for catalytic oxidation  

Microsoft Academic Search

New crystalline solid materials of Mo3VOx having high-dimensional structures were synthesized in a single crystalline form using a hydrothermal method where the essential structural unit in the structure already presents in the preparative solution and the fundamental structure of Mo3VOx is formed as a result of self-organization between negatively charged pentagonal units and VO2+ cations. We also synthesized metal oxides

Wataru Ueda; Masahiro Sadakane; Hitoshi Ogihara

2008-01-01

335

Tellurium content of marine manganese oxides and other manganese oxides  

USGS Publications Warehouse

Tellurium in amounts ranging from 5 to 125 parts per million was present in all of 12 samples of manganese oxide nodules from the floor of the Pacific and Indian oceans. These samples represent the first recognized points of high tellurium concentration in a sedimentary cycle. The analyses may lend support to the theory that the minor-element content of seafloor manganese nodules is derived from volcanic emanations.

Lakin, H. W.; Thompson, C. E.; Davidson, D. F.

1963-01-01

336

UNCORRECTED Microstructural characterization and isothermal oxidation behavior  

E-print Network

UNCORRECTED PROOF Microstructural characterization and isothermal oxidation behavior of hot of fine-scale microstructural characterization and isothermal oxidation of hot-pressed TiB2­ 10 10 wt.% Ti. The results of oxidation testing at 1200 °C for 12 h using a thermogravimetric analyzer illustrate near

Srivastava, Kumar Vaibhav

337

The higher oxides of nitrogen: Inhalation toxicology  

Microsoft Academic Search

The higher oxides of nitrogen (NO, NOâ, and higher valence) are highly reactive compounds encountered in a variety of occupational exposures and are principal constituents of photochemical air pollution. Their chemical properties result in direct oxidation, free radical formation, nitrosation, nitrite ion release, and paramagnetic interactions with heme. NO is formed from the oxidation of atmospheric Nâ in the internal

T. Guidotti

1978-01-01

338

Evaluating Environmental Influences Oxidation Kinetics by a  

E-print Network

Evaluating Environmental Influences on AsIII Oxidation Kinetics by a Poorly Crystalline Mn strategies for remediation of As-contaminated waters. In this study, the influence of goethite (R in solution interact with Mn-oxide binding sites, thus influencing the rate and amount of AsIII oxidized

Sparks, Donald L.

339

Cerium and yttrium oxide nanoparticles are neuroprotective  

Microsoft Academic Search

The responses of cells exposed to nanoparticles have been studied with regard to toxicity, but very little attention has been paid to the possibility that some types of particles can protect cells from various forms of lethal stress. It is shown here that nanoparticles composed of cerium oxide or yttrium oxide protect nerve cells from oxidative stress and that the

David. Schubert; Richard Dargusch; Joan Raitano; Siu-Wai Chan

2006-01-01

340

OXIDANT FORMATION IN THE GENERATION OF OZONE  

EPA Science Inventory

Ozone samples generated by UV photolysis and silent electric discharge upon air or oxygen were examined to determine if other oxidants were formed. Chemical and physical methods (IR and UV spectroscopy) failed to show the presence of such oxidants. Absence of such oxidants was al...

341

Electrical Conductivity Measurement of Oxides Melts  

Microsoft Academic Search

Notwithstanding on variety of existing processes of induction skull melting of oxides, electrical and thermal properties of oxides melts are practically unknown. From the other hand, liquid-phase synthesis of Hi-Tech oxides materials such as new ceramics, monocrystals and glasses, requires knowledge of melts properties up to 3700 K. Inasmuch as the main physical property, which influence to the melt power

I. Pozniak; A. Pechenkov; A. Shatunov

342

Oxidation and Reduction Reactions in Organic Chemistry  

ERIC Educational Resources Information Center

A variety of approaches to the concept of oxidation and reduction appear in organic textbooks. The method proposed here is different than most published approaches. The oxidation state is calculated by totaling the number of heterogeneous atoms, [pi]-bonds, and rings. A comparison of the oxidation states of reactant and product determine what type…

Shibley, Ivan A., Jr.; Amaral, Katie E.; Aurentz, David J.; McCaully, Ronald J.

2010-01-01

343

The Role of the Nucleus in Oxidation  

Microsoft Academic Search

Injury produces in the leaf-cells of the Indian Pipe (Monotropa uniflora) a darkening which is due to oxidation. The oxidation is much more rapid in the nucleus than in the cytoplasm and the facts indicate that this is also the case with the oxidation of the uninjured cell

W. J. V. Osterhout

1917-01-01

344

THE ROLE OF THE NUCLEUS IN OXIDATION.  

PubMed

Injury produces in the leaf-cells of the Indian Pipe (Monotropa uniflora) a darkening which is due to oxidation. The oxidation is much more rapid in the nucleus than in the cytoplasm and the facts indicate that this is also the case with the oxidation of the uninjured cell. PMID:17758977

Osterhout, W J

1917-10-12

345

Silicon membrane nanofilters from sacrificial oxide removal  

Microsoft Academic Search

Silicon micropore filter designs using a sacrificial oxide removal technique are described. These filters utilize surface and bulk micromachining for precise control of pore sizes in the tens of nanometers range. The semipermeable membrane of the sacrificial layer filters (SLFs) is typically composed of sandwiched p+ polysilicon\\/oxide\\/p+ silicon layers where the sacrificial oxide between the two silicon layers determines the

Wen-Hwa Chu; Ruby Chin; Tony Huen; Mauro Ferrari

1999-01-01

346

Air Quality Criteria for Sulfur Oxides.  

ERIC Educational Resources Information Center

Included is a literature review which comprehensively discusses knowledge of the sulfur oxides commonly found in the atmosphere. The subject content is represented by the 10 chapter titles: Physical and Chemical Properties and the Atmospheric Reactions of the Oxides of Sulfur; Sources and Methods of Measurements of Sulfur Oxides in the Atmosphere;…

National Air Pollution Control Administration (DHEW), Washington, DC.

347

REVIEW OF THE MUTAGENICITY OF ETHYLENE OXIDE  

EPA Science Inventory

Ethylene oxide has been shown to be an effective mutagen in a variety of organisms ranging from bacteria to mammalian cells. here is also an association between ethylene oxide exposure and human somatic cell cytogenetic damage. urthermore, ethylene oxide has been shown to alkylat...

348

Oxidation in HVOF-sprayed steel  

SciTech Connect

It is widely held that most of the oxidation in thermally sprayed coatings occurs on the surface of the droplet after it has flattened. The evidence in this paper suggests that, for the conditions studied here, oxidation of the top surface of flattened droplets is not the dominant oxidation mechanism. In this study, a mild steel wire (AISI 1025) was sprayed using a high-velocity oxy-fuel (HVOF) torch onto copper and aluminum substrates. Ion milling and Auger spectroscopy were used to examine the distribution of oxides within individual splats. Conventional metallographic analysis was also used to study oxide distributions within coatings that were sprayed under the same conditions. An analytical model for oxidation of the exposed surface of a splat is presented. Based on literature data, the model assumes that diffusion of iron through a solid FeO layer is the rate limiting factor in forming the oxide on the top surface of a splat. An FeO layer only a few thousandths of a micron thick is predicted to form on the splat surface as it cools. However, the experimental evidence shows that the oxide layers are typically 100x thicker than the predicted value. These thick, oxide layers are not always observed on the top surface of a splat. Indeed, in some instances the oxide layer is on the bottom, and the metal is on the top. The observed oxide distributions are more consistently explained if most of the oxide formed before the droplets impact the substrate.

Smith, M.F.; Neiser, R.A.; Dykhuizen, R.C.

1997-08-01

349

Long-term oxidation of superalloys  

Microsoft Academic Search

The oxidation of 24 commercially available superalloys was measured after exposure in still air at up to 1150°C for up to 10,000 hr. The total depth affected by oxidation, which includes subscale reactions, followed the expected exponential relationship with temperature and the expected parabolic relationship with exposure time at 1000°C; oxidation of “Haynes” 25 and TD nickel chromium was not

C. L. Angerman

1972-01-01

350

Separation medium containing thermally exfoliated graphite oxide  

NASA Technical Reports Server (NTRS)

A separation medium, such as a chromatography filling or packing, containing a modified graphite oxide material, which is a thermally exfoliated graphite oxide with a surface area of from about 300 m.sup.2/g to 2600 m.sup.2/g, wherein the thermally exfoliated graphite oxide has a surface that has been at least partially functionalized.

Prud'homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor); Herrera-Alonso, Margarita (Inventor)

2012-01-01

351

Detection of oxidation in human serum lipoproteins  

E-print Network

???????????????????????. In Vivo Oxidation?????????????????????. In Vitro Oxidation????????????????????? Thiobarbituric Acid Reactive Substances (TBARS) Assay.????? Density Separations????????????.???????? Fluorescence?????????????..?????????.. Matrix-Assisted Laser... Assay???.???????????????????.. Separation and Profiling of Lipoprotein Classes by Density Gradient Ultracentrifugation: Influence of Oxidation????????..??... Influence of Fluorescent Probe on Lipoprotein Profiles???...??? Influence of CsBiY vs Na...

Myers, Christine Lee

2006-04-12

352

Oxidation reactions on neutral cobalt oxide clusters: experimental and theoretical studies  

E-print Network

Oxidation reactions on neutral cobalt oxide clusters: experimental and theoretical studies Yan Xie.1039/b915590b Reactions of neutral cobalt oxide clusters (ComOn, m = 3�9, n = 3�13) with CO, NO, C2H2 the oxidation reactions; the Co3O4 cluster has the highest reactivity for reactions with CO and NO. Cluster

Rocca, Jorge J.

353

Within-plant isoprene oxidation confirmed by direct emissions of oxidation products methyl vinyl ketone and  

E-print Network

Within-plant isoprene oxidation confirmed by direct emissions of oxidation products methyl vinyl is converted to a variety of oxidized hydrocarbons, provid- ing higher order reactants for the production of organic nitrates and tropospheric ozone, reducing the availabil- ity of oxidants for the breakdown

Silver, Whendee

354

PILOT PLANT PREPARATION OF THORIUM OXIDE AND THORIUM-URANIUM OXIDE DURING FISCAL YEAR 1960  

Microsoft Academic Search

Test quantities of thoria (aporoximately 3800 lb of thorium oxide and ; 3200 lb of mixed thorium-uranium oxide) were prepared during FY-1960 for members ; of the Reactor Experimental Engineering Division (REED). For preparation of ; thorium oxide, the calcination temperature was varied from 650 to 1800 deg C. The ; surface area of the fired oxide ranged from 0.5

Winget; R. H. Jr

1960-01-01

355

Oxidation effect on templating of metal oxide nanoparticles within block copolymers  

E-print Network

Oxidation effect on templating of metal oxide nanoparticles within block copolymers Pinar Akcora a-norbornene dicarboxylic acid) (NOR-NORCOOH) have been synthesized and processed to template metal oxide nanoparticle. Block copolymers with iron oxide nano- particles have been used, for example, in the development of nano

Kofinas, Peter

356

Carbon and functionalized graphene oxide coated vanadium oxide electrodes for lithium ion batteries  

NASA Astrophysics Data System (ADS)

Carbon- and graphene oxide-coated vanadium oxide nanomaterials were synthesized from a VOSO4 sol using a hydrothermal method to prepare electrodes for lithium ion batteries. The synthesized materials were characterized using x-ray diffraction, scanning electron microscopy and transmission electron microscopy. Electrochemical results show that graphene oxide coated vanadium oxide electrodes have higher capacity than the carbon coated ones.

Reddy Channu, V. S.; Ravichandran, D.; Rambabu, B.; Holze, Rudolf

2014-06-01

357

UV–visible studies of nickel oxide thin film grown by thermal oxidation of nickel  

Microsoft Academic Search

In this work, we report an experimental study on optical properties of nickel oxide thin film by UV–visible spectroscopy. The nickel oxide thin film is grown by the oxidation of nickel deposited on ITO (tin doped indium oxide) coated glass substrate. The phase formation and electrical properties are studied with XRD and electrometer, respectively. On heat treatment at 500°C for

P. Mohanty; Chandana Rath; P. Mallick; R. Biswal; N. C. Mishra

2010-01-01

358

Oxidation of dimethylselenide by ??MnO2: Oxidation product and factors affecting oxidation rate  

USGS Publications Warehouse

Volatile dimethylselenide (DMSe) was transformed to a nonvolatile Se compound in a ??-MnO2 suspension. The nonvolatile product was a single compound identified as dimethylselenoxide based on its mass spectra pattern. After 24 h, 100% of the DMSe added to a ??-MnO2 suspension was converted to nonpurgable Se as opposed to 20%, 18%, and 4% conversion for chromate, permanganate, and the filtrate from the suspension, respectively. Manganese was found in solution after reaction. These results imply that the reaction between manganese oxide and DMSe was a heterogeneous redox reaction involving solid phase ??-MnO2 and solution phase DMSe. Oxidation of DMSe to dimethylselenoxide [OSe(CH3)2] by a ??-MnO2 suspension appears to be first order with respect to ??-MnO2, to DMSe, and to hydrogen ion with an overall rate law of d[OSe(CH3)2 ]/dt = 95 M-2 min-1 [MnO2]1[DMSe]1[H+]1 for the MnO2 concentration range of 0.89 ?? 10-3 - 2.46 ?? 10-3 M, the DMSe concentration range of 3.9 ?? 10-7 - 15.5 ?? 10-7 M Se, and a hydrogen ion concentation range of 7.4 ?? 10-6 -9.5 ?? 10-8 M. A general surface site adsorption model is consistent with this rate equation if the uncharged |OMnOH is the surface adsorption site. DMSe acts as a Lewis base, and the manganese oxide surface acts as a Lewis acid. DMSe adsorption to |OMnOH can be viewed as a Lewis acid/ base complex between the largely p orbitals of the DMSe lone pair and the unoccupied eg orbitals on manganese oxide. For such a complex, frontier molecular orbital theory predicts electron transfer to occur via an inner-sphere complex between the DMSe and the manganese oxide. ?? 1995 American Chemical Society.

Wang, B.; Burau, R.G.

1995-01-01

359

Influence of doping with third group oxides on properties of zinc oxide thin films  

SciTech Connect

The study of modifications in structural, optical and electrical properties of vacuum evaporated zinc oxide thin films on doping with III group oxides namely aluminum oxide, gallium oxide and indium oxide are reported. It was observed that all the films have transmittance ranging from 85 to 95%. The variation in optical properties with dopants is discussed. On doping the film with III group oxides, the conductivity of the films showed an excellent improvement of the order of 10{sup 3} {Omega}{sup -1} cm{sup -1}. The measurements of activation energy showed that all three oxide doped films have 2 donor levels below the conduction band.

Palimar, Sowmya, E-mail: sowmya0124@gmail.com; Bangera, Kasturi V.; Shivakumar, G. K. [National Institute of Technology Karnataka, Thin Film Laboratory, Physics Department (India)

2013-03-15

360

Supported and mixed oxide catalysts based on iron and titanium for the oxidative decomposition of chlorobenzene  

Microsoft Academic Search

Iron oxide supported on titanium dioxide (Fe2O3\\/TiO2) and iron–titanium mixed oxide (Fe–Ti-oxide) catalysts were prepared via wetness impregnation and sol–gel methods, respectively. The catalytic activity of the two materials for the oxidation of chlorobenzene was studied and compared with the activity of pure titanium and iron oxides as well as MgO-supported iron oxide. Fe2O3\\/TiO2 and Fe–Ti-oxide have shown higher catalytic

Abbas Khaleel; Aysha Al-Nayli

2008-01-01

361

Nano-sized layered aluminium or zinc-manganese oxides as efficient water oxidizing catalysts.  

PubMed

Nano-sized layered aluminium or zinc-manganese oxides were synthesized and characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction spectrometry, dynamic light scattering and atomic absorption spectroscopy. These oxides showed efficient water oxidizing activity in the presence of cerium(IV) ammonium nitrate as a non-oxo transfer oxidant. Amounts of dissolved manganese, zinc or aluminium, and water oxidation activities of these oxides were reported and compared with other manganese oxides. A mechanism for oxygen evolution and possible roles for zinc or aluminium ions are also proposed. PMID:22565665

Najafpour, Mohammad Mahdi; Pashaei, Babak; Nayeri, Sara

2012-06-21

362

Oxidized In-containing III-V(100) surfaces: Formation of crystalline oxide films and semiconductor-oxide interfaces  

NASA Astrophysics Data System (ADS)

Previously found oxidized III-V semiconductor surfaces have been generally structurally disordered and useless for applications. We disclose a family of well-ordered oxidized InAs, InGaAs, InP, and InSb surfaces found by experiments. The found epitaxial oxide-III-V interface is insulating and free of defects related to the harmful Fermi-level pinning, which opens up new possibilities to develop long-sought III-V metal-oxide-semiconductor transistors. Calculations reveal that the early stages in the oxidation process include only O-III bonds due to the geometry of the III-V(100)c(8×2) substrate, which is responsible for the formation of the ordered interface. The found surfaces provide a different platform to study the oxidation and properties of oxides, e.g., the origins of the photoemission shifts and electronic structures, using surface science methods.

Punkkinen, M. P. J.; Laukkanen, P.; Lång, J.; Kuzmin, M.; Tuominen, M.; Tuominen, V.; Dahl, J.; Pessa, M.; Guina, M.; Kokko, K.; Sadowski, J.; Johansson, B.; Väyrynen, I. J.; Vitos, L.

2011-05-01

363

Leakage Current Reduction Mechanism of Oxide-Nitride-Oxide Inter-Poly Dielectrics through the Post Plasma Oxidation Treatment  

NASA Astrophysics Data System (ADS)

High quality oxide-nitride-oxide (ONO) inter-poly dielectrics were successfully fabricated by the optimized plasma oxidation without H2. The bottom low pressure chemical vapor deposition (LPCVD) oxides treated by the conventional N2O annealing step were subjected to the post deposition process using a plasma treatment. This process reduces both the leakage current and the stress-induced leakage current (SILC), while no thickness increase of the bottom LPCVD oxides was observed due to the plasma treatment. Based on the photo electron injection technique, it is found that the O2 plasma oxidation method significantly reduces the defect centers located at 1.67 nm away from the bottom oxide/floating gate interface.

Lee, Woong; Jee, Jeonggeun; Yoo, Dae-Han; Lee, Eun-Young; Bok, Jinkwon; Hyung, Younwoo; Kim, Seoksik; Kang, Chang-Jin; Moon, Joo-Tae; Roh, Yonghan

2011-04-01

364

Literature survey on oxidations and fatigue lives at elevated temperatures  

NASA Technical Reports Server (NTRS)

Nickel-base superalloys are the most complex and the most widely used for high temperature applications such as aircraft engine components. The desirable properties of nickel-base superalloys at high temperatures are tensile strength, thermomechanical fatigue resistance, low thermal expansion, as well as oxidation resistance. At elevated temperature, fatigue cracks are often initiated by grain boundary oxidation, and fatigue cracks often propagate along grain boundaries, where the oxidation rate is higher. Oxidation takes place at the interface between metal and gas. Properties of the metal substrate, the gaseous environment, as well as the oxides formed all interact to make the oxidation behavior of nickel-base superalloys extremely complicated. The important topics include general oxidation, selective oxidation, internal oxidation, grain boundary oxidation, multilayer oxide structure, accelerated oxidation under stress, stress-generation during oxidation, composition and substrate microstructural changes due to prolonged oxidation, fatigue crack initiation at oxidized grain boundaries and the oxidation accelerated fatigue crack propagation along grain boundaries.

Liu, H. W.; Oshida, Y.

1984-01-01

365

Photosensitized oxidation of unsaturated polymers  

NASA Technical Reports Server (NTRS)

The photosensitized oxidation or singlet oxygenation of unsaturated hydrocarbon polymers and of their model compounds was reviewed. Emphasis was on cis and trans forms of 1,4-polyisoprene, 1,4-polybutadiene and 1,2-poly(1,4-hexadiene), and on 1,4-poly(2,3-dimethyl-1,3-butadiene). The microstructural changes which occur in these polymers on reaction with O2-1 in solution were investigated by infrared H-1 and C-13 NMR spectroscopy. The polymers were shown to yield allylic hydroperoxides with shifted double bonds according to the ene mechanism established for simple olefins. The photosensitized oxidation of the above unsaturated polymer exhibited zero order kinetics, the relative rates paralleling the reactivities of the corresponding simple olefins towards O2-1.

Golub, M. A.

1979-01-01

366

Aromatic-radical oxidation kinetics  

SciTech Connect

The detailed experimental study of the oxidation of cyclopentadiene has been continued in the Princeton flow reactor during this year. Experimental problems that plagued the initial effort to study this compound have been solved and have permitted the observation of some surprising trends in intermediate species profiles. There are unique, important differences between some of these profiles and those of previously studied hydrocarbons. Co{sub 2} is produced early in the reaction sequence even before CO has reached its maximum concentration, the point at which rapid CO{sub 2} production is usually seen during the oxidation of hydrocarbons. Even more usual is that the concentration of CO{sub 2} for a given time or extent of reaction increases as the system is made more fuel rich. 5 refs., 4 figs.

Glassman, I.; Brezinsky, K.

1991-01-01

367

Biochemistry of Dissimilatory Sulfur Oxidation  

SciTech Connect

The long term goals of this research were to define the substrate oxidation pathways, the electron transport mechanisms, and the modes of energy conservation employed during the dissimilatory oxidation of sulfur practiced by various species of the thiobacilli. Specific adhesion of the thiobacilli to elemental sulfur was studied by electrical impedance, dynamic light scattering, laser Doppler velocimetry, and optical trapping methods. The conclusion is that the thiobacilli appear to express specific receptors that enable the bacteria to recognize and adhere to insoluble sulfur. The enzyme tetrathionate oxidase was purified from two species of the thiobacilli. Extensive structural and functional studies were conducted on adenosine 5'-phosphosulfate reductase purified from cell-free extracts of Thiobacillus denitrificans. The kinetic mechanism of rhodanese was studied.

Blake II, R.

2003-05-30

368

Structure of Liquid Aluminum Oxide  

NASA Astrophysics Data System (ADS)

The total structure factor, S\\(Q\\), and the corresponding radial distribution function, G\\(r\\), for supercooled and stable liquid aluminum oxide have been measured with x-ray synchrotron radiation. The specimens were levitated in a conical nozzle and melted with a laser, achieving temperatures in the range of 2200-2700 K. The first two peaks in S\\(Q\\) reveal intermediate-range order and dense random packing of atoms, similar to that observed in many network liquids. The first two peaks in G\\(r\\) are consistent with AlO5-4 structural units and show that Al2O3 undergoes a major structural rearrangement on melting with an Al coordination change from octahedral to tetrahedral. The structure does not change appreciably with temperature in the stable and supercooled liquid. Implications of these results are discussed in connection with the solidification of aluminum oxide.

Ansell, Stuart; Krishnan, Shankar; Weber, J. K. Richard; Felten, John J.; Nordine, Paul C.; Beno, Mark A.; Price, David L.; Saboungi, Marie-Louise

1997-01-01

369

Molecular Structure of Nitrous Oxide  

NSDL National Science Digital Library

Nitrous Oxide is a colorless, nonflammable, bacteriostatic gas with slightly sweet odor that was first discovered in 1793 by the English scientist and clergyman Joseph Priestley. Originally, it was used as "laughing gas" for recreational enjoyment and public shows. But in the early of 1840s, Nitrous oxide found a more scientific use as an anesthetic in clinical dentistry and medicine. At room temperature, N2O is quite inert with most substances, including alkali metals, halogens, and even ozone. It is therefore widely used as a propellant in aerosol cans in place of the CFC's, which damage the ozone layer. N2O is occasionally injected into the air intake of the combustion chambers (also called "cylinders") of racing cars to provide more power to the engine giving the car an exceptional acceleration.

2003-06-04

370

Haemophilus influenzae and oxidative stress.  

PubMed

Haemophilus influenzae is a commensal of the human upper respiratory tract. H. influenzae can, however, move out of its commensal niche and cause multiple respiratory tract diseases. Such diseases include otitis media in young children, as well as exacerbations of chronic obstructive pulmonary disease (COPD), sinusitis, conjunctivitis, and bronchitis. During the course of colonization and infection, H. influenzae must withstand oxidative stress generated by multiple reactive oxygen species produced endogenously, by other co-pathogens and by host cells. H. influenzae has, therefore, evolved multiple mechanisms that protect the cell against oxygen-generated stresses. In this review, we will describe these systems relative to the well-described systems in Escherichia coli. Moreover, we will compare how H. influenzae combats the effect of oxidative stress as a necessary phenotype for its roles as both a successful commensal and pathogen. PMID:22919631

Harrison, Alistair; Bakaletz, Lauren O; Munson, Robert S

2012-01-01

371

Photoelectrochemical response and stability of titanium–zinc mixed oxide films formed by thermal oxidation  

Microsoft Academic Search

The photoelectrochemical properties of titanium–zinc mixed oxide films formed by thermal oxidation of a titanium sheet with a zinc deposited overlayer were studied in pH 8.4 borate buffer solution at 298 K. The oxides were composed of ZnO (wurtzite), TiO2 (rutile), and ZnTi2O4 depending on the oxidation temperatures. Under xenon light illumination, photocurrents were observed for the oxides and these

Isao Saeki; Jun Setaka; Ryusaburo Furuichi; Hidetaka Konno

1999-01-01

372

Total Oxidation of Carbon-Monoxide and Methane over Transition Metal Fluorite Oxide Composite Catalysts  

Microsoft Academic Search

Cu-Ce-O and Au-Ce-O catalysts were characterized by XRD, XPS, and STEM. Copper in small amounts showed a strong tendency to associate with cerium oxide, When the cerium oxide surface was saturated with copper, excess copper formed bulk copper oxide particles. The cuprous(+1) oxidation state was identified by XPS for the copper clusters distributed in cerium oxide, while gold in the

W. Liu; M. Flytzani-Stephanopoulos

1995-01-01

373

Oxidation state of Mn in the Mn oxide produced by Leptothrix discophora SS1  

Microsoft Academic Search

Leptothrix discophora SS-1 excretes at least one Mn{sup 2+}-oxidizing protein that, in association with acidic exopolymers, catalyzes a rapid oxidation of Mn{sup 2+}. Iodometric titration of Mn oxide product showed that the oxidation state of Mn increased with age of the oxide from 3.32 in samples 11 hours old to 3.62 in samples formed over a period of 30 days.

L. F. Adams; W. C. Ghiorse

1988-01-01

374

Polyaniline nanowire synthesis templated by DNA  

NASA Astrophysics Data System (ADS)

DNA-templated polyaniline nanowires and networks are synthesized using three different methods. The resulting DNA/polyaniline hybrids are fully characterized using atomic force microscopy, UV-vis spectroscopy and current-voltage measurements. Oxidative polymerization of polyaniline at moderate pH values is accomplished using ammonium persulfate as an oxidant, or alternatively in an enzymatic oxidation by hydrogen peroxide using horseradish peroxidase, or by photo-oxidation using a ruthenium complex as photo-oxidant. Atomic force microscopy shows that all three methods lead to the preferential growth of polyaniline along DNA templates. With ammonium persulfate, polyaniline can be grown on DNA templates already immobilized on a surface. Current-voltage measurements are successfully conducted on DNA/polyaniline networks synthesized by the enzymatic method and the photo-oxidation method. The conductance is found to be consistent with values measured for undoped polyaniline films.

Nickels, Patrick; Dittmer, Wendy U.; Beyer, Stefan; Kotthaus, Jörg P.; Simmel, Friedrich C.

2004-11-01

375

Preparation of thin film superconducting oxides  

SciTech Connect

This patent describes a method of preparing a copper oxide-based superconducting oxide/noble metal composite film. It comprises: making an organic liquid solution of the cation constituents of the oxide film by chelating a precursor solution containing the cation constituents with an organic acid and adding a polymerizing alcohol; adding a noble metal to the organic liquid solution; forming the solution into a liquid film; drying and heating the liquid film solution to obtain a solid organic polymer or resin; and firing the polymer to obtain the copper oxide-based superconducting oxide/noble metal composite film.

Chiang, Y.M.

1990-01-30

376

Heterogeneous photocatalytic oxidation of atmospheric trace contaminants  

NASA Technical Reports Server (NTRS)

The following subject areas are covered: (1) design and construction of continuous flow photoreactor for study of oxidation of trace atmospheric contaminants; (2) establishment of kinetics of acetone oxidation including adsorption equilibration, variation of oxidation rate with acetone concentration and water (inhibitor), and variation of rate and apparent quantum yield with light intensity; (3) exploration of kinetics of butanol oxidation, including rate variation with concentration of butanol, and lack of inhibition by water; and (4) exploration of kinetics of catalyst deactivation during oxidation of butanol, including deactivation rate, influence of dark conditions, and establishment of photocatalytic regeneration of activity in alcohol-free air.

Ollis, David F.; Peral, Jose

1991-01-01

377

Nitric Oxide Activates Cyclooxygenase Enzymes  

Microsoft Academic Search

We have evaluated the role of nitric oxide (NO) on the activity of the constitutive and induced forms of cyclooxygenase (COX; COX-1 and COX-2, respectively). Induction of NO synthase (NOS) and COX (COX-2) in the mouse macrophage cell line RAW264.7 by Escherichia coli lipopolysaccharide (1 mu g\\/ml, 18 h) caused an increase in the release of nitrite (NO^-_2) and prostaglandin

Daniela Salvemini; Thomas P. Misko; Jaime L. Masferrer; Karen Seibert; Mark G. Currie; Philip Needleman

1993-01-01

378

Graphene oxide based smart fluids.  

PubMed

Graphene oxide (GO), a graphene-related material containing oxygen-functional groups, has attracted considerable attention because of its strongly hydrophilic behavior and potential use in GO-hybrid composites. We put our focus on the fabrication and rheological characteristics of GO-based electrorheological and magnetorheological smart fluids under electric and magnetic fields, respectively in this Highlight. A brief perspective on the significant role of GO in tribology and the amphiphilic characteristics of Pickering emulsions are also included. PMID:25068905

Zhang, Wen Ling; Choi, Hyoung Jin

2014-09-21

379

Oxidative stabilization of acrylic fibres  

Microsoft Academic Search

When acrylic fibres are heat treated for various times at 220 to 250 C, they form dark, insoluble structures of uncertain\\u000a chemical character which are inert to many strong oxidizing and reducing agents. The heat-treated fibres are, however, rapidly\\u000a decoloured by warm alkaline hypochlorite solutions. When fibres which have undergone short-time heat treatment are subjected\\u000a to the hypochlorite, incubation periods

S. S. Chen; J. Herms; L. H. Peebles; D. R. Uhlmann

1981-01-01

380

Catalyst for carbon monoxide oxidation  

NASA Technical Reports Server (NTRS)

A catalyst for the combination of CO and O2 to form CO2 which includes a platinum group metal, e.g., platinum; a reducible metal oxide having mulitple valence states, e.g., SnO2; and a compound which can bind water to its structure, e.g., silica gel. This catalyst is ideally suited for application to high powered, pulsed, CO2 lasers operating in a sealed or closed cycle condition.

Upchurch, Billy T. (inventor); Miller, Irvin M. (inventor); Brown, David R. (inventor); Davis, Patricia P. (inventor); Schryer, David R. (inventor); Brown, Kenneth G. (inventor); Vannorman, John D. (inventor)

1991-01-01

381

Catalyst for carbon monoxide oxidation  

NASA Technical Reports Server (NTRS)

A catalyst is disclosed for the combination of CO and O2 to form CO2, which includes a platinum group metal (e.g., platinum); a reducable metal oxide having multiple valence states (e.g., SnO2); and a compound which can bind water to its structure (e.g., silica gel). This catalyst is ideally suited for application to high-powered pulsed, CO2 lasers operating in a sealed or closed-cycle condition.

Upchurch, Billy T. (inventor); Miller, Irvin M. (inventor); Brown, David R. (inventor); Davis, Patricia (inventor); Schryer, David R. (inventor); Brown, Kenneth G. (inventor); Vannorman, John D. (inventor)

1990-01-01

382

Neurotoxicity of manganese oxide nanomaterials  

Microsoft Academic Search

Manganese (Mn) toxicity in humans has been observed as manganism, a disease that resembles Parkinson’s disease. The mechanism\\u000a of Mn toxicity and the chemical forms that may be responsible for its neurotoxicity are not well understood. We examined the\\u000a toxicity of Mn oxide nanomaterials in a neuronal precursor cell model, using the MTS assay to evaluate mitochondrial function\\u000a in living

Diana M. Stefanescu; Ali Khoshnan; Paul H. Patterson; Janet G. Hering

2009-01-01

383

Oxidative stress responses in yeast  

Microsoft Academic Search

Yeast, and especially S. cerevisiae, is a unique eukaryotic model organism for studying oxidative stress and its cellular responses. S. cerevisiae has become a very powerful tool to decipher the complexity of these biologically important responses, because it offers the\\u000a relative simplicity of a single celled eukaryotic organism that enables the combination and integration of genetic, biochemical,\\u000a physico-chemical, cell biological,

Michel B. Toledano; Agnes Delaunay; Benoit Biteau; Daniel Spector; Dulce Azevedo

384

"Magic" vicinal zinc oxide surfaces.  

PubMed

The structure of (0001) oriented ZnO single crystal surfaces is investigated by scanning tunneling microscopy. Depending on the preparation conditions, faceting of the crystals into large areas of {101¯4} surface orientation occurs. This restructuring of the surface is shown to be a consequence of dipole compensation and charge neutralization. A new stabilization mechanism of polar oxide surfaces is found which is based on the formation of vicinal surfaces with special electronic and structural properties. PMID:24010455

Zheng, Hao; Gruyters, Markus; Pehlke, Eckhard; Berndt, Richard

2013-08-23

385

Nitric oxide reburning with methane  

SciTech Connect

This paper deals with initial findings from the ongoing, three-year DOE program that began on 02/01/1995. The program involves computer simulation studies to aid in planning and conducting a series of experiments that will extend the knowledge of reburning process. The objective of this work is to find nitric oxide reduction effectiveness for various reburning fuels and identify both homogeneous and heterogeneous reaction mechanisms characterizing NO reduction.

Kumpaty, S.K. [Rust Coll., Holly Springs, MS (United States); Subramanian, K. [Subramanian (Kannikeswaran), Houston, TX (United States)

1996-12-31

386

Oxidation of Reduced Codehydrogenase I  

Microsoft Academic Search

THE discovery of an enzyme1,2 capable of catalysing the oxidation of reduced codehydrogenase I (cozymase, CoI) at an extremely rapid rate3 naturally raises the question as to what part this enzyme plays in hydrogen transport. There is considerable evidence1,2,4,5 that this enzyme (diaphorase) catalyzes the reaction between dihydrocozymase and the cytochrome system, and Dewan and Green2 have suggested that cytochromes

V. R. Potter

1939-01-01

387

Chemistry of tungsten oxide bronzes  

Microsoft Academic Search

Ammonium paratungstate (APT) is the generally accepted starting material in tungsten manufacturing. The dopants, which are responsible for the non-sag properties, are given to some tungsten oxide bronze (TOB)-type compounds which are formed by thermal reductive decomposition of APT. The doped TOB is reduced in a H2 atmosphere to tungsten metal grains. The powder metallurgical processing and the following thermomechanical

T. Szalay

1995-01-01

388

Nitric oxide and the gut  

Microsoft Academic Search

Nitric oxide (NO) has been implicated as a modulator of blood flow, motility, electrolyte and water transport, and the function\\u000a of endothelial cells, platelets, mast cells, and macrophages within the digestive system. In addition, a number of reports\\u000a have demonstrated that NO possesses potent anti-inflammatory properties, whereas results from an equally impressive number\\u000a of studies suggest that NO may promote

David Jourd’heuil; Matthew B. Grisham; D. Neil Granger

1999-01-01

389

Nitric oxide and substance dependence  

Microsoft Academic Search

The free-radical gas nitric oxide (NO) plays an important role in a diverse range of physiological processes. It is synthesized from the precursor l-arginine by the enzyme NO synthase (NOS), which transforms l-arginine into NO and citrulline. This synthetic pathway exists in the central nervous system (CNS), and NO appears to be a messenger molecule in the CNS, fulfilling most

I. Tayfun Uzbay; Michael W. Oglesby

2001-01-01

390

Systems of highly refractory oxides  

Microsoft Academic Search

An account is presented below of the application of these techniques to a study of the system Gd203SrO. The method of high-temperature DTA, which might prove useful also in investigations of materials other than oxides, is described in some detail. In the construction of the DTA apparatus, the need arose to improve the method of fixing the so-called jet thermocouple,

L. M. Lopato; A. V. Shevchenko; A. E. Kushchevskii

1972-01-01

391

Coal combustion by wet oxidation  

SciTech Connect

The combustion of coal by wet oxidation was studied by the Center for Waste Management Programs, of Michigan Technological University. In wet oxidation a combustible material, such as coal, is reacted with oxygen in the presence of liquid water. The reaction is typically carried out in the range of 204/sup 0/C (400/sup 0/F) to 353/sup 0/C (650/sup 0/F) with sufficient pressure to maintain the water present in the liquid state, and provide the partial pressure of oxygen in the gas phase necessary to carry out the reaction. Experimental studies to explore the key reaction parameters of temperature, time, oxidant, catalyst, coal type, and mesh size were conducted by running batch tests in a one-gallon stirred autoclave. The factors exhibiting the greatest effect on the extent of reaction were temperature and residence time. The effect of temperature was studied from 204/sup 0/C (400/sup 0/F) to 260/sup 0/C (500/sup 0/F) with a residence time from 600 to 3600 seconds. From this data, the reaction activation energy of 2.7 x 10/sup 4/ calories per mole was determined for a high-volatile-A-Bituminous type coal. The reaction rate constant may be determined at any temperature from the activation energy using the Arrhenius equation. Additional data were generated on the effect of mesh size and different coal types. A sample of peat was also tested. Two catalysts were evaluated, and their effects on reaction rate presented in the report. In addition to the high temperature combustion, low temperature desulfurization is discussed. Desulfurization can improve low grade coal to be used in conventional combustion methods. It was found that 90% of the sulfur can be removed from the coal by wet oxidation with the carbon untouched. Further desulfurization studies are indicated.

Bettinger, J.A.; Lamparter, R.A.; McDowell, D.C.

1980-11-15

392

Kinetic Modeling of Propane Oxidation  

Microsoft Academic Search

The oxidation of propane was studied in a jet-stirred flow reactor in the temperature range 900-1200 K at pressure s extending from 1 to 10 atrn for a wide range of fuel-oxygen equivalence ratios (0.15 to 4.0), A comput er program has been developed to model the experimental data using a chemical kinetic reaction mechan ism. A direct method to

P. DAGAUT; M. CATHONNET; J. C. BOETINER; F. GAILLARD

1987-01-01

393

Nitric oxide function in atherosclerosis  

PubMed Central

Atherosclerosis is a chronic inflammatory process in the intima of conduit arteries, which disturbs the endothelium-dependent regulation of the vascular tone by the labile liposoluble radical nitric oxide (NO) formed by the constitutive endothelial nitric oxide synthase (eNOS). This defect predisposes to coronary vasospasm and cardiac ischaemia, with anginal pain as the typical clinical manifestation. It is now appreciated that endothelial dysfunction is an early event in atherogenesis and that it may also involve the microcirculation, in which atherosclerotic lesions do not develop. On the other hand, the inflammatory environment in atherosclerotic plaques may result in the expression of the inducible NO synthase (iNOS) isozyme. Whether the dysfunction in endothelial NO production is causal to, or the result of, atherosclerotic lesion formation is still highly debated. Most evidence supports the hypothesis that constitutive endothelial NO release protects against atherogenesis e.g. by preventing smooth muscle cell proliferation and leukocyte adhesion. Nitric oxide generated by the inducible isozyme may be beneficial by replacing the failing endothelial production but excessive release may damage the vascular wall cells, especially in combination with reactive oxygen intermediates. PMID:18472828

Matthys, K. E.

1997-01-01

394

Exercise, oxidative stress and hormesis.  

PubMed

Physical inactivity leads to increased incidence of a variety of diseases and it can be regarded as one of the end points of the exercise-associated hormesis curve. On the other hand, regular exercise, with moderate intensity and duration, has a wide range of beneficial effects on the body including the fact that it improves cardio-vascular function, partly by a nitric oxide-mediated adaptation, and may reduce the incidence of Alzheimer's disease by enhanced concentration of neurotrophins and by the modulation of redox homeostasis. Mechanical damage-mediated adaptation results in increased muscle mass and increased resistance to stressors. Physical inactivity or strenuous exercise bouts increase the risk of infection, while moderate exercise up-regulates the immune system. Single bouts of exercise increases, and regular exercise decreases the oxidative challenge to the body, whereas excessive exercise and overtraining lead to damaging oxidative stress and thus are an indication of the other end point of the hormetic response. Based upon the genetic setup, regular moderate physical exercise/activity provides systemic beneficial effects, including improved physiological function, decreased incidence of disease and a higher quality of life. PMID:17869589

Radak, Zsolt; Chung, Hae Y; Koltai, Erika; Taylor, Albert W; Goto, Sataro

2008-01-01

395

Arsenic mobilization in the critical zone: Oxidation by hydrous manganese oxide Jason S. Fischel, fischjs06@juniata.edu1  

E-print Network

Arsenic mobilization in the critical zone: Oxidation by hydrous manganese oxide GEOC 112 Jason S manganese (Mn) oxides, even in low concentrations, to oxidize trace metals such as arsenic from arsenite [As

Sparks, Donald L.

396

KINETICS AND MECHANISMS OF CHROMIUM(III) OXIDATION AND PRECIPITATION ON MANGANESE OXIDES, IN REAL-TIME AND AT THE  

E-print Network

KINETICS AND MECHANISMS OF CHROMIUM(III) OXIDATION AND PRECIPITATION ON MANGANESE OXIDES, IN REAL(III) OXIDATION AND PRECIPITATION ON MANGANESE OXIDES, IN REAL-TIME AND AT THE MOLECULAR LEVEL by Gautier Landrot

Sparks, Donald L.

397

Electro-catalytic reduction of nitrogen oxides  

SciTech Connect

Nitrogen oxides have been linked to a broad range of air pollution problems including acid rain and the atmospheric production of photochemical ozone. Over twenty million tons of nitrogen oxides are emitted into the atmosphere each year as a result of the high temperature combustion of fossil fuels. Efforts to control nitrogen oxides emissions have lagged because of the generally low discharge concentrations of nitrogen oxides in combustion exhaust and because nitrogen oxides are more difficult to remove due to their lower reactivity. No catalyst has yet been found that will achieve significant reduction of nitrogen oxides in an oxidizing environment. Oxygen in the exhaust stream competes with nitrogen oxides for the active catalyst sites. Also, the dissociated oxygen atoms produced by decomposition of nitrogen oxides deactivate the surface of the catalyst. Externally applied electric fields have been used to control oxygen adsorption on metal and semi-conductor surfaces. In this investigation, a stream containing nitric oxide has been subjected to intense electric fields in the presence of catalyst materials including steel, stainless steel, and gold plated stainless steel wools and glass wool. The electric fields have been generated using DC, AC and rectified AC potentials in the range of 0--20 KV. The effect of parameters such as inlet nitric oxide concentration, oxygen and water content, gas residence time and temperature have also been studied.

McLarnon, C.R.

1989-12-01

398

Nanowire-based All Oxide Solar Cells  

SciTech Connect

We present an all-oxide solar cell fabricated from vertically oriented zinc oxide nanowires and cuprous oxide nanoparticles. Our solar cell consists of vertically oriented n-type zinc oxide nanowires, surrounded by a film constructed from p-type cuprous oxide nanoparticles. Our solution-based synthesis of inexpensive and environmentally benign oxide materials in a solar cell would allow for the facile production of large-scale photovoltaic devices. We found that the solar cell performance is enhanced with the addition of an intermediate oxide insulating layer between the nanowires and the nanoparticles. This observation of the important dependence of the shunt resistance on the photovoltaic performance is widely applicable to any nanowire solar cell constructed with the nanowire array in direct contact with one electrode.

Yang*, Benjamin D. Yuhas and Peidong; Yang, Peidong

2008-12-07

399

Oxidation-assisted ductility of aluminium nanowires.  

PubMed

Oxidation can drastically change mechanical properties of nanostructures that typically have large surface-to-volume ratios. However, the underlying mechanisms describing the effect oxidation has on the mechanical properties of nanostructures have yet to be characterized. Here we use reactive molecular dynamics and show that the oxidation enhances the aluminium nanowire ductility, and the oxide shell exhibits superplastic behaviour. The oxide shell decreases the aluminium dislocation nucleation stress by increasing the activation volume and the number of nucleation sites. Superplasticity of the amorphous oxide shell is due to viscous flow as a result of healing of the broken aluminium-oxygen bonds by oxygen diffusion, below a critical strain rate. The interplay between the strain rate and oxidation rate is not only essential for designing nanodevices in ambient environments, but also controls interface properties in large-scale deformation processes. PMID:24887649

Sen, Fatih G; Alpas, Ahmet T; van Duin, Adri C T; Qi, Yue

2014-01-01

400

Nitric Oxide Synthases and Atrial Fibrillation  

PubMed Central

Oxidative stress has been implicated in the pathogenesis of atrial fibrillation. There are multiple systems in the myocardium which contribute to redox homeostasis, and loss of homeostasis can result in oxidative stress. Potential sources of oxidants include nitric oxide synthases (NOS), which normally produce nitric oxide in the heart. Two NOS isoforms (1 and 3) are normally expressed in the heart. During pathologies such as heart failure, there is induction of NOS 2 in multiple cell types in the myocardium. In certain conditions, the NOS enzymes may become uncoupled, shifting from production of nitric oxide to superoxide anion, a potent free radical and oxidant. Multiple lines of evidence suggest a role for NOS in the pathogenesis of atrial fibrillation. Therapeutic approaches to reduce atrial fibrillation by modulation of NOS activity may be beneficial, although further investigation of this strategy is needed. PMID:22536189

Bonilla, Ingrid M.; Sridhar, Arun; Gyorke, Sandor; Cardounel, Arturo J.; Carnes, Cynthia A.

2012-01-01

401

The oxidative cost of unstable social dominance.  

PubMed

High social rank is expected to incur fitness costs under unstable social conditions. A disruption of the oxidative balance may underlie such effects, but how markers of oxidative stress vary in relation to social rank and stability is unknown. We examined in mandrills whether the mating season characterized by social instability between males (but not between females) affected their oxidative balance differently according to their social rank. Outside the mating season, high-ranking males showed the lowest levels of oxidative damage, while during the mating season, they were the only males to experience increased oxidative damage. In contrast, the mating season increased oxidative stress in all females, irrespective of their social rank. These results support the hypothesis that the coupling between social rank and social stability is responsible for differential costs in terms of oxidative stress, which may explain inter-individual differences in susceptibility to socially induced health issues. PMID:24902748

Beaulieu, Michaël; Mboumba, Sylvère; Willaume, Eric; Kappeler, Peter M; Charpentier, Marie J E

2014-08-01

402

Comprehensive portrait of cholesterol containing oxidized membrane.  

PubMed

Biological membranes are under significant oxidative stress caused by reactive oxygen species mostly originating during cellular respiration. Double bonds of the unsaturated lipids are most prone to oxidation, which might lead to shortening of the oxidized chain and inserting of terminal either aldehyde or carboxylic group. Structural rearrangement of oxidized lipids, addressed already, is mainly associated with looping back of the hydrophilic terminal group. This contribution utilizing dual-focus fluorescence correlation spectroscopy and electron paramagnetic resonance as well as atomistic molecular dynamics simulations focuses on the overall changes of the membrane structural and dynamical properties once it becomes oxidized. Particularly, attention is paid to cholesterol rearrangement in the oxidized membrane revealing its preferable interaction with carbonyls of the oxidized chains. In this view cholesterol seems to have a tendency to repair, rather than condense, the bilayer. PMID:24565796

Stefl, Martin; Sachl, Radek; Ol?y?ska, Agnieszka; Amaro, Mariana; Savchenko, Dariya; Deyneka, Alexander; Hermetter, Albin; Cwiklik, Lukasz; Humpolí?ková, Jana; Hof, Martin

2014-07-01

403

Oxidation-reduction catalyst and its process of use  

NASA Technical Reports Server (NTRS)

This invention relates generally to a ruthenium stabilized oxidation-reduction catalyst useful for oxidizing carbon monoxide, and volatile organic compounds, and reducing nitrogen oxide species in oxidizing environments, substantially without the formation of toxic and volatile ruthenium oxide species upon said oxidizing environment being at high temperatures.

Jordan, Jeffrey D. (Inventor); Watkins, Anthony Neal (Inventor); Schryer, Jacqueline L. (Inventor); Oglesby, Donald M. (Inventor)

2008-01-01

404

An impedance spectroscopy study of oxide films formed during high temperature oxidation of an austenitic stainless steel  

Microsoft Academic Search

Impedance spectroscopy has been used to study an oxide film formed on an AISI304 austentic stainless steel by oxidation at 800°C for 200 h. Impedance spectra of the oxide film clearly showed two semicircles, which correspond to two independent oxide layers present in the oxide film. The oxide film was also examined by using scanning electron microscopy (SEM), X-ray photoelectron

S.-H. Song; P. Xiao

2003-01-01

405

75 FR 11877 - Review of the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Oxides...  

Federal Register 2010, 2011, 2012, 2013

...Ambient Air Quality Standards for Oxides of Nitrogen and Oxides of Sulfur AGENCY: Environmental...Ambient Air Quality Standards for Oxides of Nitrogen and Oxides of Sulfur: First External...welfare-based) NAAQS for oxides of nitrogen (NO X ) and oxides of sulfur...

2010-03-12

406

75 FR 57463 - Review of the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Oxides...  

Federal Register 2010, 2011, 2012, 2013

...Ambient Air Quality Standards for Oxides of Nitrogen and Oxides of Sulfur AGENCY: Environmental...Ambient Air Quality Standards for Oxides of Nitrogen and Oxides of Sulfur: Second External...welfare-based) NAAQS for oxides of nitrogen (NO X ) and oxides of sulfur...

2010-09-21

407

Reactive vaporization of oxides in solid oxide fuel cell systems  

NASA Astrophysics Data System (ADS)

Metals such as chromium, aluminum and silicon are of extreme technological and industrial importance due to the corrosion resistance they offer in oxidizing environments at high temperature. Much of this robustness is based on the formation of a thin, well-adhered metal-oxide (MO) layer on the surface of the metal. In particularly corrosive environments or at high-enough temperatures and or pressures, the MO will chemically react with constituents in the surrounding gas, removing atoms from the solid. For many systems, material loss and subsequent mechanical failure is the foremost concern. However, in solid oxide fuel cell (SOFC) systems, the presence of gaseous metal species leads to severe degradation in electrochemical performance well before mechanical limits are reached. Reactive vaporization from ferritic stainless steels, chromia, aluminosilicates and a candidate electrode material (Sr2VMoO6), was investigated using the transpiration method. Two novel collection methods were employed: condensation of vapors on wafer collectors analyzed with Rutherford backscattering spectrometry (RBS); and, condensation of vapors on quartz wool analyzed via inductively coupled plasma mass spectroscopy (ICP-MS). Identification and quantification of vapor species provided assessment of material performance in SOFC environments. Experiments demonstrated that Cr vapor species from ferritic stainless steels used for SOFC interconnect applications could be reduced by as much as one order of magnitude through the application of barrier coatings. Base alloys were compared and exhibited a variety of Cr vaporization rates despite being similar in composition, thus illustrating the importance of minor elemental constituents in the alloy. Measurements identified Si as the primary volatile element in aluminosilicate materials when Si concentrations in the bulk material were as low as one percent. Aluminosilicate materials demonstrated a burn out phase during the first hundred hours at 800°C in humid oxidizing environments, where large amounts of Si and other elements were vaporizing. Mass transport rate versus flow rate experiments on pure Cr2O3 indicated that sample surface area influences the measured Cr vapor pressure. This finding helps explain the range of values reported in literature for the equilibrium rate constant of the most common Cr vaporization reaction in SOFC environments.

Key, Camas Fought

408

Platinum/Tin Oxide/Silica Gel Catalyst Oxidizes CO  

NASA Technical Reports Server (NTRS)

Heterogeneous catalyst of platinum, tin oxide, and silica gel combines small concentrations of laser dissociation products, CO and O2, to form CO22 during long times at ambient temperature. Developed as means to prevent accumulation of these products in sealed CO2 lasers. Effective at ambient operating temperatures and installs directly in laser envelope. Formulated to have very high surface area and to chemisorb controlled quantities of moisture: chemisorbed water contained within and upon its structure, makes it highly active and very longlived so only small quantity needed for long times.

Upchurch, Billy T.; Davis, Patricia P.; Schryer, David R.; Miller, Irvin M.; Brown, David; Van Norman, John D.; Brown, Kenneth G.

1991-01-01

409

Water oxidation by amorphous cobalt-based oxides: volume activity and proton transfer to electrolyte bases.  

PubMed

Water oxidation in the neutral pH regime catalyzed by amorphous transition-metal oxides is of high interest in energy science. Crucial determinants of electrocatalytic activity were investigated for a cobalt-based oxide film electrodeposited at various thicknesses on inert electrodes. For water oxidation at low current densities, the turnover frequency (TOF) per cobalt ion of the bulk material stayed fully constant for variation of the thickness of the oxide film by a factor of 100 (from about 15?nm to 1.5??m). Thickness variation changed neither the nanostructure of the outer film surface nor the atomic structure of the oxide catalyst significantly. These findings imply catalytic activity of the bulk hydrated oxide material. Nonclassical dependence on pH was observed. For buffered electrolytes with pKa values of the buffer base ranging from 4.7 (acetate) to 10.3 (hydrogen carbonate), the catalytic activity reflected the protonation state of the buffer base in the electrolyte solution directly and not the intrinsic catalytic properties of the oxide itself. It is proposed that catalysis of water oxidation occurs within the bulk hydrated oxide film at the margins of cobalt oxide fragments of molecular dimensions. At high current densities, the availability of a proton-accepting base at the catalyst-electrolyte interface controls the rate of water oxidation. The reported findings may be of general relevance for water oxidation catalyzed at moderate pH by amorphous transition-metal oxides. PMID:24449514

Klingan, Katharina; Ringleb, Franziska; Zaharieva, Ivelina; Heidkamp, Jonathan; Chernev, Petko; Gonzalez-Flores, Diego; Risch, Marcel; Fischer, Anna; Dau, Holger

2014-05-01

410

Oxidative stress-mediated antibacterial activity of graphene oxide and reduced graphene oxide in Pseudomonas aeruginosa  

PubMed Central

Background Graphene holds great promise for potential use in next-generation electronic and photonic devices due to its unique high carrier mobility, good optical transparency, large surface area, and biocompatibility. The aim of this study was to investigate the antibacterial effects of graphene oxide (GO) and reduced graphene oxide (rGO) in Pseudomonas aeruginosa. In this work, we used a novel reducing agent, betamercaptoethanol (BME), for synthesis of graphene to avoid the use of toxic materials. To uncover the impacts of GO and rGO on human health, the antibacterial activity of two types of graphene-based material toward a bacterial model P. aeruginosa was studied and compared. Methods The synthesized GO and rGO was characterized by ultraviolet-visible absorption spectroscopy, particle-size analyzer, X-ray diffraction, scanning electron microscopy and Raman spectroscopy. Further, to explain the antimicrobial activity of graphene oxide and reduced graphene oxide, we employed various assays, such as cell growth, cell viability, reactive oxygen species generation, and DNA fragmentation. Results Ultraviolet-visible spectra of the samples confirmed the transition of GO into graphene. Dynamic light-scattering analyses showed the average size among the two types of graphene materials. X-ray diffraction data validated the structure of graphene sheets, and high-resolution scanning electron microscopy was employed to investigate the morphologies of prepared graphene. Raman spectroscopy data indicated the removal of oxygen-containing functional groups from the surface of GO and the formation of graphene. The exposure of cells to GO and rGO induced the production of superoxide radical anion and loss of cell viability. Results suggest that the antibacterial activities are contributed to by loss of cell viability, induced oxidative stress, and DNA fragmentation. Conclusion The antibacterial activities of GO and rGO against P. aeruginosa were compared. The loss of P. aeruginosa viability increased in a dose- and time-dependent manner. Exposure to GO and rGO induced significant production of superoxide radical anion compared to control. GO and rGO showed dose-dependent antibacterial activity against P. aeruginosa cells through the generation of reactive oxygen species, leading to cell death, which was further confirmed through resulting nuclear fragmentation. The data presented here are novel in that they prove that GO and rGO are effective bactericidal agents against P. aeruginosa, which would be used as a future antibacterial agent. PMID:23226696

Gurunathan, Sangiliyandi; Han, Jae Woong; Dayem, Ahmed Abdal; Eppakayala, Vasuki; Kim, Jin-Hoi

2012-01-01

411

Silicene oxides: formation, structures and electronic properties  

PubMed Central

Understanding the oxidation of silicon has been critical to the success of all types of silicon materials, which are the cornerstones of modern silicon technologies. For the recent experimentally obtained two-dimensional silicene, oxidation should also be addressed to enable the development of silicene-based devices. Here we focus on silicene oxides (SOs) that result from the partial or full oxidation of silicene in the framework of density functional theory. It is found that the formation of SOs greatly depends on oxidation conditions, which concern the oxidizing agents of oxygen and hydroxyl. The honeycomb lattice of silicene may be preserved, distorted or destroyed after oxidation. The charge state of Si in partially oxidized silicene ranges from +1 to +3, while that in fully oxidized silicene is +4. Metals, semimetals, semiconductors and insulators can all be found among the SOs, which show a wide spectrum of electronic structures. Our work indicates that the oxidation of silicene should be exquisitely controlled to obtain specific SOs with desired electronic properties. PMID:24336409

Wang, Rong; Pi, Xiaodong; Ni, Zhenyi; Liu, Yong; Lin, Shisheng; Xu, Mingsheng; Yang, Deren

2013-01-01

412

Role of oxidants in microbial pathophysiology.  

PubMed Central

Reactive oxidant species (superoxide, hydrogen peroxide, hydroxyl radical, hypohalous acid, and nitric oxide) are involved in many of the complex interactions between the invading microorganism and its host. Regardless of the source of these compounds or whether they are produced under normal conditions or those of oxidative stress, these oxidants exhibit a broad range of toxic effects to biomolecules that are essential for cell survival. Production of these oxidants by microorganisms enables them to have a survival advantage in their environment. Host oxidant production, especially by phagocytes, is a counteractive mechanism aimed at microbial killing. However, this mechanism may be contribute to a deleterious consequence of oxidant exposure, i.e., inflammatory tissue injury. Both the host and the microorganism have evolved complex adaptive mechanisms to deflect oxidant-mediated damage, including enzymatic and nonenzymatic oxidant-scavenging systems. This review discusses the formation of reactive oxidant species in vivo and how they mediate many of the processes involved in the complex interplay between microbial invasion and host defense. PMID:8993856

Miller, R A; Britigan, B E

1997-01-01

413

Trapping Centers in Unibond Buried Oxides  

NASA Astrophysics Data System (ADS)

/ The charge trapping properties of Unibond buried oxides have been characterized with electron spin /resonance (ESR) and capacitance-voltage (CV) measurements. Unibond is a revolutionary new /silicon-on-insulator (SOI) technology that seemingly combines the best of both separated-by-implanted-oxygen /(SIMOX) and bond-and-etchback-silicon-on-insulator (BESOI). SOI materials have several advantages over bulk /silicon, including speed, power, and radiation hardness for outerspace applications. / We find that the E' family of oxide defects dominate charge trapping in Unibond buried oxides. In many /ways the charge trapping properties of Unibond buried oxides are very similar to those of thermally grown oxides. /However, the presence of hydrogen complexed E' centers in Unibond buried oxides, indicates a difference /between the defect structures responsible for charge trapping in Unibond buried oxides and thermally grown /oxides. / Our results suggest that, the buried oxide quality of the Unibond wafers are very similar to those of /thermally grown oxides, and thus the Unibond process is a promising new SOI technology.

Wallace, Brian; Lenahan, Patrick; Conely, John

1997-03-01

414

Oxidative damage to 5-methylcytosine in DNA.  

PubMed Central

Exposure of pyrimidines of DNA to ionizing radiation under aerobic conditions or oxidizing agents results in attack on the 5,6 double bond of the pyrimidine ring or on the exocyclic 5-methyl group. The primary product of oxidation of the 5,6 double bond of thymine is thymine glycol, while oxidation of the 5-methyl group yields 5-hydroxymethyluracil. Oxidation of the 5,6 double bond of cytosine yields cytosine glycol, which decomposes to 5-hydroxycytosine, 5-hydroxyuracil and uracil glycol, all of which are repaired in DNA by Escherichia coli endonuclease III. We now describe the products of oxidation of 5-methylcytosine in DNA. Poly(dG-[3H]dmC) was gamma-irradiated or oxidized with hydrogen peroxide in the presence of Fe3+ and ascorbic acid. The oxidized co-polymer was incubated with endonuclease III or 5-hydroxymethyluracil-DNA glycosylase, to determine whether repairable products were formed, or digested to 2'-deoxyribonucleosides, to determine the total complement of oxidative products. Oxidative attack on 5-methylcytosine resulted primarily in formation of thymine glycol. The radiogenic yield of thymine glycol in poly(dG-dmC) was the same as that in poly(dA-dT), demonstrating that 5-methylcytosine residues in DNA were equally susceptible to radiation-induced oxidation as were thymine residues. PMID:7667100

Zuo, S; Boorstein, R J; Teebor, G W

1995-01-01

415

CO-oxidation catalysts: Low-temperature CO oxidation over Noble-Metal Reducible Oxide (NMRO) catalysts  

NASA Technical Reports Server (NTRS)

Oxidation of CO to CO2 is an important reaction technologically and environmentally and a complex and interesting reaction scientifically. In most cases, the reaction is carried out in order to remove CO as an environmental hazard. A major application of heterogeneous catalysts is catalytic oxidation of CO in the exhaust of combustion devices. The reaction over catalysts in exhaust gas is fast and often mass-transfer-limited since exhaust gases are hot and O2/CO ratios are high. The main challenges to catalyst designers are to control thermal sintering and chemical poisoning of the active materials. The effect of the noble metal on the oxide is discussed, followed by the effect of the oxide on the noble metal, the interaction of the noble metal and oxide to form unique catalytic sites, and the possible ways in which the CO oxidation reaction is catalyzed by the NMRO materials.

Herz, Richard K.

1990-01-01

416

Products from salt cake residue-oxide  

SciTech Connect

This paper describes some of the work done in Phase 1 of a multi-year, five-phase program aimed at demonstrating the economic feasibility of producing commercial-scale quantities of commodity materials derived from salt cake residue-oxide. The amount of salt cake generated annually in the U. S. is estimated to be 510,000 tons, including 340,000 tons of residue-oxide. Used beverage can (UBC) processing accounts for the majority of residue-oxide that could be made available for further processing into commercial products. To characterize the composition of residue-oxide, eight residue-oxide samples from various secondary processors were obtained and analyzed. Surprisingly, the composition of residue-oxide was found to be independent of source or alloy family being processed, with the exception of slightly elevated silicon levels in 3XX and UBC residue-oxide samples. Major phases detected in the residue-oxide were alumina, spinel, and aluminum hydroxides. Preliminary economic analyses indicated that the refractory market appears to be the best choice for high value-added products produced from residue-oxide with minimum processing. Bench-scale tests indicated that low silicon-containing residue-oxide is ready to enter this market, but the elevated silicon content of UBC and 3XX residue-oxide preclude this possibility. A separation technology should be ed to remove silicon-containing species from the alumina and spinel values present in oxide. This technology would then allow UBC and 3XX residue-oxides to be d to significantly higher value-added products.

Hryn, J.N.; Daniels, E.J. [Argonne National Lab., IL (United States); Gurganus, T.B.; Tomaswick, K.M. [Aluminum Co. of America, Alcoa Center, PA (United States). Alcoa Technical Center

1995-12-31

417

The growth of iron oxide, nickel oxide and cobalt oxide thin films by laser ablation from metal targets  

Microsoft Academic Search

Thin films of iron oxide, nickel oxide and cobalt oxide have been grown by the technique of laser ablation. The films have been deposited on [100] LaAlO3, SrTiO3, MgO and cubic zirconia (YSZ); on sapphire, mica, glass slides and Kapton. High quality c axis [100] oriented growth occurs for Fe3O4 and NiO on the first three substrates; on YSZ the

R. J. Kennedy

1995-01-01

418

Novel oxide-oxide fiber reinforced hot gas filter development  

SciTech Connect

The objective of this program is to fabricate and test oxide fiber reinforced composite hot gas filter elements for advanced power generation systems. The level of mechanical durability exhibited by the currently available filters in field tests indicates that more rugged filters are required to meet the demands of large power generation systems. Furthermore, long term corrosion resistance of currently available filters has yet to be demonstrated in PFBC systems. The essential requirements of a composite material designed to meet the program objective for a toughened hot gas filter include the following: Stable continuous fiber; rigid porous matrix; engineered fiber-matrix interface; and cost effectiveness. Based on properties, availability, and cost, Mitsui`s ALMAX alumina fiber and 3M`s NEXTEL 610 alumina fiber were selected as the oxide reinforcement fibers. In order to meet the economic goals of the program it is essential that the cost and amount of continuous fiber be minimized. A four axis filament winder will be used to fabricate filter Preforms in a variety of fiber architectures. Carbon was used as the initial fiber coating because it was known to be resistant to the Processing chemicals. The coating was produced by pyrolysis of the resin based sizings on the continuous fibers. The matrix of the composite filter is comprised of chopped ceramic fiber. Saffil fiber was used for all compositions in this program.

Wagner, R.A.

1995-12-01

419

Oxidation of the Ediacaran ocean.  

PubMed

Oxygenation of the Earth's surface is increasingly thought to have occurred in two steps. The first step, which occurred approximately 2,300 million years (Myr) ago, involved a significant increase in atmospheric oxygen concentrations and oxygenation of the surface ocean. A further increase in atmospheric oxygen appears to have taken place during the late Neoproterozoic period ( approximately 800-542 Myr ago). This increase may have stimulated the evolution of macroscopic multicellular animals and the subsequent radiation of calcified invertebrates, and may have led to oxygenation of the deep ocean. However, the nature and timing of Neoproterozoic oxidation remain uncertain. Here we present high-resolution carbon isotope and sulphur isotope records from the Huqf Supergroup, Sultanate of Oman, that cover most of the Ediacaran period (approximately 635 to approximately 548 Myr ago). These records indicate that the ocean became increasingly oxygenated after the end of the Marinoan glaciation, and they allow us to identify three distinct stages of oxidation. When considered in the context of other records from this period, our data indicate that certain groups of eukaryotic organisms appeared and diversified during the second and third stages of oxygenation. The second stage corresponds with the Shuram excursion in the carbon isotope record and seems to have involved the oxidation of a large reservoir of organic carbon suspended in the deep ocean, indicating that this event may have had a key role in the evolution of eukaryotic organisms. Our data thus provide new insights into the oxygenation of the Ediacaran ocean and the stepwise restructuring of the carbon and sulphur cycles that occurred during this significant period of Earth's history. PMID:17151665

Fike, D A; Grotzinger, J P; Pratt, L M; Summons, R E

2006-12-01

420

Sulfur species in graphene oxide.  

PubMed

The structure of graphene oxide (GO) is of crucial importance for its chemical functionalization. However, the sulfur content present in GO prepared by Hummers' method has only been addressed by a few authors so far. It has been reported that hydrolysis of sulfur species takes place and that stable sulfonic groups are present in graphite oxide. In this manuscript, in contrast to earlier reports, sulfate species are identified that are covalently bound to GO and still present after extensive aqueous work-up. Additionally, we exclude the possibility that sulfonic groups are present in GO as major species after aqueous work up. Our results are based on bulk characterization of graphene oxide by thermogravimetry and subsequent analysis of the decomposition products using mass spectroscopy and infrared spectroscopy. Up to now, the combustion temperature between 200 and 300 °C remained almost unaddressed. In a temperature dependant experiment we reveal two main decomposition steps that differ in temperature and that are closely related to the sulfur species in GO. While the decomposition, between 200 and 300 °C, is related to the degradation of organosulfate, the other one, between 700 and 800 °C, is assigned to the pyrolysis of inorganic sulfate. Furthermore, organosulfate is to some extent responsible for the reactivity of GO. Therefore, the structural model of GO was extended by adding organosulfate in addition to epoxy and hydroxyl groups, which are predominantly covalently bound above and below the carbon skeleton. Furthermore, the identification of organosulfate groups beneath epoxy groups makes new molecular architectures feasible and can be used to explain the properties of GO in various applications. PMID:23780799

Eigler, Siegfried; Dotzer, Christoph; Hof, Ferdinand; Bauer, Walter; Hirsch, Andreas

2013-07-15

421

Plasma deposition of oxide cathodes  

NASA Astrophysics Data System (ADS)

Vacuum arc deposition is employed to create a barium and/or strontium plasma which is subsequently deposited/implanted onto a nickel cathode substrate. The primary motivation for this work is the critical need for a reliable, repeatable, long-lived thermionic cathode for the production of high power, microsecond duration microwave pulses; such cathodes may also have applicability for lower current density continuous wave devices. This novel approach to manufacturing an oxide cathode eliminates the binders that may subsequently (and unpredictably) poison cathode emission. Removal of the poisoning mechanisms has yielded oxide cathodes capable of emission densities in the 20 A/cm2 regime. Cathode lifetime and emission may be varied via the control over the deposition parameters such as coating thickness, implantation energy, and plasma stoichiometry. The deposition is performed by generating a cathodic arc discharge at the surface of a barium or barium-strontium alloy rod. The metal plasma thus created is then deposited on the substrate which can be negatively biased to encourage implantation during the deposition process. The deposition is performed with sufficient background oxygen present to oxidize the highly reactive metal coating. The plasma deposition is monitored via a rate thickness monitor, an optical emission spectrometer for plasma composition information, and an electrostatic Langmuir probe for the determination of the plasma density and temperature profile. Cathodes thus produced are analyzed by drawing pulsed current at a constant voltage for various values of decreasing cathode temperature in order to generate practical work function distributions which provide an indication of the quality and expected life time of the cathode. In support of analyzing these cathodes (as well as a variety of cathodes from other sources), a complete UHV cathode test and analysis system has been assembled which includes 3-D beam profiling, advanced temperature measurement, residual gas analysis, bulk cold work function measurement, and surface analysis with depth profiling.

Umstattd, R.; Pi, T.; Luhmann, N.; Scheitrum, G.; Caryotakis, G.; Miram, G.

1999-05-01

422

Oxidative Stress in Cardiovascular Disease  

PubMed Central

In the special issue “Oxidative Stress in Cardiovascular Disease” authors were invited to submit papers that investigate key questions in the field of cardiovascular free radical biology. The original research articles included in this issue provide important information regarding novel aspects of reactive oxygen species (ROS)-mediated signaling, which have important implications in physiological and pathophysiological cardiovascular processes. The issue also included a number of review articles that highlight areas of intense research in the fields of free radical biology and cardiovascular medicine. PMID:24722571

Csanyi, Gabor; Miller, Francis J.

2014-01-01

423

DISSOLUTION OF NEPTUNIUM OXIDE RESIDUES  

SciTech Connect

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). Samples of each type of materials proposed for processing were dissolved in a closed laboratory apparatus and the rate and total quantity of off-gas were measured. Samples of the off-gas were also analyzed. The quantity and type of solids remaining (when visible) were determined after post-dissolution filtration of the solution. Recommended conditions for dissolution of the NpO{sub 2} residues are: Solution Matrix and Loading: {approx}50 g Np/L (750 g Np in 15 L of dissolver solution), using 8 M nitric acid (HNO{sub 3}), 0.025 M potassium fluoride (KF) at greater than 100 C for at least 3 hours. Off-gas: Analysis of the off-gas indicated nitric oxide (NO), nitrogen dioxide (NO{sub 2}) and nitrous oxide (N{sub 2}O) as the only identified components. No hydrogen (H{sub 2}) was detected. The molar ratio of off-gas produced per mole of Np dissolved ranged from 0.25 to 0.4 moles of gas per mole of Np dissolved. A peak off-gas rate of {approx}0.1 scfm/kg bulk oxide was observed. Residual Solids: Pure NpO{sub 2} dissolved with little or no residue with the proposed flowsheet but the NpCo and both sweepings samples left visible solid residue after dissolution. For the NpCo and Part II Sweepings samples the residue amounted to {approx}1% of the initial material, but for the Part I Sweepings sample, the residue amounted to {approx}8 % of the initial material. These residues contained primarily aluminum (Al) and silicon (Si) compounds that did not completely dissolve under the flowsheet conditions. The residues from both sweepings samples contained minor amounts of plutonium (Pu) particles. Overall, the undissolved Np and Pu particles in the residues were a very small fraction of the total solids.

Kyser, E

2009-01-12

424

Fuel neutralization by ozone oxidation  

NASA Technical Reports Server (NTRS)

The viability of a hazardous waste disposal system based on ozone oxidation of hydrazine fuels at low aqueous concentrations in the presence of ultraviolet light (UV at 2.537 x 10(exp -7) m or 8.324 x 10(exp -7) ft) excitation was investigated. Important parameters investigated include temperature, solution pH, and ultraviolet light power. Statistically relevant experimentation was done to estimate main factor effects on performance. The best available chemical analysis technology was used to evaluate the performance of the system.

Swartz, A. B.; Agthe, R. E.; Smith, I. D.; Mulholland, J. P.

1988-01-01

425

Grain boundaries in complex oxides  

SciTech Connect

A quantitative comparison was achieved between space charge theory and segregation at grain boundaries in the model system TiO[sub 2]. The ionic space charge can be titrated from negative to positive potential. A space charge model was developed that includes the lattice defect chemistry. Defect formation energies in the Frenkel pair for TiO[sub 2] were studied. Grain boundary enthalpy was measured during coarsening. It was shown that it is the barium vacancy that forms near surfaces in donor-doped BaTiO[sub 3] electroceramics during oxidative-cooling.

Chiang, Yet-Ming.

1993-05-01

426

Infrared radiation characteristics of oxide composites  

SciTech Connect

The infrared radiation heating materials are being used for various applications. Infrared radiation characteristics of oxides and oxide composites were investigated by measuring spectral emissivity. Powders of silica and alumina and mixture of the two powders were compacted into disc shape specimens and heated at 1000{degree}C for various heating times. The infrared emissivity of specimens were measured using an infrared spectrophotometer. The spectral emissivity curve of single oxide showed a distinctive shape with intrinsic absorption zone. This absorption zone was partially compensated by making a composite with other oxide powder. However, the spectral emissivity curve changed to the different type, when a complex oxide was formed between two oxides. It was shown that a high efficiency infrared radiator can be achieved by selecting a composite suitable for a required purpose.

Kohara, S.; Tomita, Y. [Science Univ. of Tokyo, Chiba (Japan). Dept. of Materials Science and Technology

1993-12-31

427

Immunochemical detection of oxidatively damaged DNA.  

PubMed

Oxidatively damaged DNA is implicated in various diseases, including neurodegenerative disorders, cancer, diabetes, cardiovascular and inflammatory diseases as well as aging. Several methods have been developed to detect oxidatively damaged DNA. They include chromatographic techniques, the Comet assay, (32)P-postlabelling and immunochemical methods that use antibodies to detect oxidized lesions. In this review, we discuss the detection of 8-oxo-7,8-dihydro-29-deoxyguanosine (8-oxodG), the most abundant oxidized nucleoside. This lesion is frequently used as a marker of exposure to oxidants, including environmental pollutants, as well as a potential marker of disease progression. We concentrate on studies published between the years 2000 and 2011 that used enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry to detect 8-oxodG in humans, laboratory animals and in cell lines. Oxidative damage observed in these organisms resulted from disease, exposure to environmental pollutants or from in vitro treatment with various chemical and physical factors. PMID:22034834

Rossner, Pavel; Sram, Radim J

2012-04-01

428

Oxidative electrochemical switching of photochromic diarylethene compounds  

NASA Astrophysics Data System (ADS)

A series of photochromic diarylethenes compounds were synthesized and the electrochemistry and electrochemistry reaction mechanism properties were investigated. The cyclic voltammetry tests demonstrated that the colorless open-ring isomers were assigned to the unique oxidation process, but the color closed-ring isomers of these compounds were assigned to two oxidation processes. In addition, the electrochromism of diarylethene compound is observed in solution: The closed-ring reaction can be triggered by electrochemical oxidation, while the open-ring reaction must be photochemically driven. These oxidation processes properties can be useful as the oxidation processes electrochemical switching and the oxidation electrochemical switching properties of these different diarylethene isomers can be potential for electrochemistry data storages.

Fan, Congbin; Pu, Shouzhi; Liu, Weijun; Yang, Tianshe; Liu, Gang

2008-12-01

429

Management of oxidative stress by microalgae.  

PubMed

The aim of this review is to provide an overview of the current research on oxidative stress in eukaryotic microalgae and the antioxidant compounds microalgae utilize to control oxidative stress. With the potential to exploit microalgae for the large-scale production of antioxidants, interest in how microalgae manage oxidative stress is growing. Microalgae can experience increased levels of oxidative stress and toxicity as a result of environmental conditions, metals, and chemicals. The defence mechanisms for microalgae include antioxidant enzymes such as superoxide dismutase, catalase, peroxidases, and glutathione reductase, as well as non-enzymatic antioxidant molecules such as phytochelatins, pigments, polysaccharides, and polyphenols. Discussed herein are the 3 areas the literature has focused on, including how conditions stress microalgae and how microalgae respond to oxidative stress by managing reactive oxygen species. The third area is how beneficial microalgae antioxidants are when administered to cancerous mammalian cells or to rodents experiencing oxidative stress. PMID:23368282

Cirulis, Judith T; Scott, J Ashley; Ross, Gregory M

2013-01-01

430

Nanoscale oxidation and complex oxide growth on single crystal iron surfaces and external electric field effects.  

PubMed

Oxidation of iron surfaces and oxide growth mechanisms have been studied using reactive molecular dynamics. Oxide growth kinetics on Fe(100), (110), and (111) surface orientations has been investigated at various temperatures and/or an external electric field. The oxide growth kinetics decreases in the order of (110), (111), and (100) surfaces at 300 K over 1 ns timescale while higher temperature increases the oxidation rate. The oxidation rate shows a transition after an initial high rate, implying that the oxide formation mechanism evolves, with iron cation re-ordering. In early stages of surface oxide growth, oxygen transport through iron interstitial sites is dominant, yielding non-stoichiometric wüstite characteristics. The dominant oxygen inward transport decreases as the oxide thickens, evolving into more stoichiometric oxide phases such as wüstite or hematite. This also suggests that cation outward transport increases correspondingly. In addition to oxidation kinetics simulations, formed oxide layers have been relaxed in the range of 600-1500 K to investigate diffusion characteristics, fitting these results into an Arrhenius relation. The activation energy of oxygen diffusion in oxide layers formed on Fe(100), (110), and (111) surfaces was estimated to be 0.32, 0.26, and 0.28 eV, respectively. Comparison between our modeling results and literature data is then discussed. An external electric field (10 MV cm(-1)) facilitates initial oxidation kinetics by promoting oxygen transport through iron lattice interstitial sites, but reaches self-limiting thickness, showing that similar oxide formation stages are maintained when cation transport increases. The effect of the external electric field on iron oxide structure, composition, and oxide activation energy is found to be minimal, whereas cation outward migration is slightly promoted. PMID:23247653

Jeon, Byoungseon; Van Overmeere, Quentin; van Duin, Adri C T; Ramanathan, Shriram

2013-02-14

431

Oxidation state of Mn in the Mn oxide produced by Leptothrix discophora SS-1  

SciTech Connect

Leptothrix discophora SS-1 excretes at least one Mn{sup 2+}-oxidizing protein that, in association with acidic exopolymers, catalyzes a rapid oxidation of Mn{sup 2+}. Iodometric titration of Mn oxide product showed that the oxidation state of Mn increased with age of the oxide from 3.32 in samples 11 hours old to 3.62 in samples formed over a period of 30 days. Electron diffraction of 90-day old samples showed evidence of poorly crystalline Mn(IV) oxides. Simultaneous measurement of oxygen consumption and Mn oxide formation during 15 min reaction periods indicated that the initial Mn product possessed an average oxidation state no greater than 3.6. Results suggest that the Mn{sup 2+}-oxidizing system of Leptothrix discophora SS-1 first generates Mn oxide with an average oxidation state close to Mn(III). Aging increases this oxidation state to give the mixed Mn(III, IV) oxide product observed in older samples.

Adams, L.F.; Ghiorse, W.C. (Cornell Univ., Ithaca, NY (USA))

1988-08-01

432

Metal oxide composite dosimeter method and material  

DOEpatents

The present invention is a method of measuring a radiation dose wherein a radiation responsive material consisting essentially of metal oxide is first exposed to ionizing radiation. The metal oxide is then stimulating with light thereby causing the radiation responsive material to photoluminesce. Photons emitted from the metal oxide as a result of photoluminescence may be counted to provide a measure of the ionizing radiation.

Miller, Steven D. (Richland, WA)

1998-01-01

433

Solid-oxide fuel cell electrolyte  

SciTech Connect

This invention is comprised of a solid-oxide electrolyte operable at between 600{degrees}C and 800{degrees}C and a method of producing the solid-oxide electrolyte. The solid-oxide electrolyte comprises a combination of a compound having a weak metal-oxygen interactions with a compound having stronger metal-oxygen interactions whereby the resulting combination has both strong and weak metal-oxygen interaction properties.

Bloom, I.D.; Hash, M.C.; Krumpelt, M.

1991-12-31

434

Impact of Oxidative Stress in Fetal Programming  

PubMed Central

Intrauterine stress induces increased risk of adult disease through fetal programming mechanisms. Oxidative stress can be generated by several conditions, such as, prenatal hypoxia, maternal under- and overnutrition, and excessive glucocorticoid exposure. The role of oxidant molecules as signaling factors in fetal programming via epigenetic mechanisms is discussed. By linking oxidative stress with dysregulation of specific target genes, we may be able to develop therapeutic strategies that protect against organ dysfunction in the programmed offspring. PMID:22848830

Thompson, Loren P.; Al-Hasan, Yazan

2012-01-01

435

Method for depositing an oxide coating  

NASA Technical Reports Server (NTRS)

A metal oxide coating is plated onto a metal substrate at the cathode from an acid solution which contains an oxidizing agent. The process is particularly useful for producing solar panels. Conventional plating at the cathode avoids the presence of oxidizing agents. Coatings made in accordance with the invention are stable both at high temperatures and while under the influence of high photon flux in the visible range.

Mcdonald, G. E. (inventor)

1982-01-01

436

Ethylene oxide and acetaldehyde in hot cores  

NASA Astrophysics Data System (ADS)

Context. Ethylene oxide (c-C2H4O), and its isomer acetaldehyde (CH3CHO), are important complex organic molecules because of their potential role in the formation of amino acids. The discovery of ethylene oxide in hot cores suggests the presence of ring-shaped molecules with more than 3 carbon atoms such as furan (c-C4H4O), to which ribose, the sugar found in DNA, is closely related. Aims: Despite the fact that acetaldehyde is ubiquitous in the interstellar medium, ethylene oxide has not yet been detected in cold sources. We aim to understand the chemistry of the formation and loss of ethylene oxide in hot and cold interstellar objects (i) by including in a revised gas-grain network some recent experimental results on grain surfaces and (ii) by comparison with the chemical behaviour of its isomer, acetaldehyde. Methods: We introduce a complete chemical network for ethylene oxide using a revised gas-grain chemical model. We test the code for the case of a hot core. The model allows us to predict the gaseous and solid ethylene oxide abundances during a cooling-down phase prior to star formation and during the subsequent warm-up phase. We can therefore predict at what temperatures ethylene oxide forms on grain surfaces and at what temperature it starts to desorb into the gas phase. Results: The model reproduces the observed gaseous abundances of ethylene oxide and acetaldehyde towards high-mass star-forming regions. In addition, our results show that ethylene oxide may be present in outer and cooler regions of hot cores where its isomer has already been detected. Our new results are compared with previous results, which focused on the formation of ethylene oxide only. Conclusions: Despite their different chemical structures, the chemistry of ethylene oxide is coupled to that of acetaldehyde, suggesting that acetaldehyde may be used as a tracer for ethylene oxide towards cold cores.

Occhiogrosso, A.; Vasyunin, A.; Herbst, E.; Viti, S.; Ward, M. D.; Price, S. D.; Brown, W. A.

2014-04-01

437

Oxidative stress in microorganisms—I  

Microsoft Academic Search

Oxidative stress in microbial cells shares many similarities with other cell types but it has its specific features which\\u000a may differe in prokaryotic and eukaryotic cells. We survey here the properties and actions of primary sources of oxidative\\u000a stress, the role of transition metals in oxidative stress and cell protective machinery of microbial cells, and compare them\\u000a with analogous features

K. Sigler; J. Chaloupka; J. Brozmanová; N. Stadler; M. Höfer

1999-01-01

438

Investigations of Nonstoichiometric Tungsten Oxide Nanoparticles  

Microsoft Academic Search

Recently, pure phases of hollow multi-walled WS2 nanotubes were prepared from a surface reaction with reduced tungsten oxide nanowhiskers. During the process, which starts with WO3?x nanoparticles and finishes with WS2 nanotubes, particular care has been devoted to the evolution of the tungsten oxide cores once the first encapsulating WS2 layer has been formed. The reduced tungsten oxide phases were

G. L. Frey; A. Rothschild; J. Sloan; R. Rosentsveig; R. Popovitz-Biro; R. Tenne

2001-01-01

439

Oxidative imbalance in alzheimer’s disease  

Microsoft Academic Search

Oxidative stress is a striking feature of susceptible neurons in the Alzheimer’s disease brain. Importantly, because oxidative\\u000a stress is an early event in Alzheimer’s disease, proximal to the development of hallmark pathologies, it likely plays an important\\u000a role in the pathogenesis of the disease. Investigations into the cause of such oxidative stress show that interactions between\\u000a abnormal mitochondria and disturbed

Xiongwei Zhu; Hyoung-gon Lee; Gemma Casadesus; Jesus Avila; Kelly Drew; George Perry; Mark A. Smith

2005-01-01

440

Electrochemical lithium intercalation in disordered manganese oxides  

Microsoft Academic Search

Four highly disordered manganese oxides were prepared by reduction of sodium permanganate by chloride, iodide, hydrogen peroxide or oxalate in aqueous medium containing a large excess of Li+ ions, yielding hydrated oxides with Mn valence in the range 3.80–3.92. Thermogravimetric studies showed that the iodide-reduced oxide can be dehydrated to 92% at 240°C, while the other three ones retain water

A Ibarra Palos; M Anne; P Strobel

2001-01-01

441

Predicting the radiation tolerance of oxides  

SciTech Connect

We have used atomistic computer simulations and ion beam irradiations to examine radiation damage accumulation in multicomponent oxides, We have developed contour energy maps via computer simulations to predict the effects of oxide structure and chemical composition on radiation-induced atomic disorder, defect migration, and swelling. Ion irradiation damage experiments have been perfonned on, pyrochlore and fluorite-structured oxide ceramics to test the predictions from computer models.

Sickafus, K. (Kurt E.); Grimes, R. W. (Robin W.)

2001-01-01

442

Biological Superoxide In Manganese Oxide Formation  

NASA Astrophysics Data System (ADS)

Manganese (Mn) oxides are among the strongest sorbents and oxidants within the environment, controlling the fate and transport of numerous elements and the degradation of recalcitrant carbon. Both bacteria and fungi mediate the oxidation of Mn(II) to Mn(III/IV) oxides but the genetic and biochemical mechanisms responsible remain poorly understood. Furthermore, the physiological basis for microbial Mn(II) oxidation remains an enigma. We have recently reported that a common marine bacterium (Roseobacter sp. AzwK-3b) oxidizes Mn(II) via reaction with extracellular superoxide (O2-) produced during exponential growth. Here we expand this superoxide-mediated Mn(II) oxidation pathway to fungi, introducing a surprising homology between prokaryotic and eukaryotic metal redox processes. For instance, Stibella aciculosa, a common soil Ascomycete filamentous fungus, precipitates Mn oxides at the base of asexual reproductive structures (synnemata) used to support conidia (Figure 1). This distribution is a consequence of localized production of superoxide (and it's dismutation product hydrogen peroxide, H2O2), leading to abiotic oxidation of Mn(II) by superoxide. Disruption of NADPH oxidase activity using the oxidoreductase inhibitor DPI leads to diminished cell differentiation and subsequent Mn(II) oxidation inhibition. Addition of Cu(II) (an effective superoxide scavenger) leads to a concentration dependent decrease in Mn oxide formation. We predict that due to the widespread production of extracellular superoxide within the fungal and likely bacterial kingdoms, biological superoxide may be an important contributor to the cycling of Mn, as well as other metals (e.g., Hg, Fe). Current and future explorations of the genes and proteins involved in superoxide production and Mn(II) oxidation will ideally lend insight into the physiological and biochemical basis for these processes.

Hansel, C.; Learman, D.; Zeiner, C.; Santelli, C. M.

2011-12-01

443

Mitochondrial thioredoxin in regulation of oxidant-induced cell death  

Microsoft Academic Search

Mitochondrial thioredoxin (mtTrx) can be oxidized in response to inducers of oxidative stress; yet the functional consequences of the oxidation have not been determined. This study evaluated the redox status of mtTrx and its association to oxidant-induced apoptosis. Results showed that mtTrx was oxidized after exposure to peroxides and diamide. Overexpression of mtTrx protected against diamide-induced oxidation and cytotoxicity. Oxidation

Yan Chen; Jiyang Cai; Dean P Jones

2006-01-01

444

Storage vault for uranium oxide  

SciTech Connect

This paper describes the conceptual design of a vault for storing uranium oxide. Unique features of this vault are the storage racks and the method of surveillance. Uranium oxide packaged in 2-l canisters would be stored in a borated concrete slab placed on the vault floor. The slab would be constructed with a rectangular array of vertical holes, each of which could contain up to two canisters. Each hole would be covered with a square tile to serve as a radiation shield and to prevent casual entry. Canisters would be held one atop the other in a basket attached to the lower surface of each tile. Continual surveillance of each storage position would be provided by a network of light sources and photosensors located along opposite edges of the storage rack such that two light beams intersect perpendicularly above each storage hole but below the radiation shield. Accessing a hole activates a unique pair of photosensors, identifying the position to the value inventory control computer system. Protection against adversarial attack and intrusion detection during nonworking hours would be provided by standard methods used in the industry. The photosensor system would protect against insiders working in collusion to divert material. This would be accomplished by limiting the material vulnerable to diversion to that authorized for access.

Hooker, G.J.

1987-01-01

445

Structure of Liquid Aluminum Oxide  

SciTech Connect

The total structure factor, S(Q), and the corresponding radial distribution function, G(r), for supercooled and stable liquid aluminum oxide have been measured with x-ray synchrotron radiation. The specimens were levitated in a conical nozzle and melted with a laser, achieving temperatures in the range of 2200{endash}2700K. The first two peaks in S(Q) reveal intermediate-range order and dense random packing of atoms, similar to that observed in many network liquids. The first two peaks in G(r) are consistent with AlO{sub 4}{sup 5-} structural units and show that Al{sub 2}O{sub 3} undergoes a major structural rearrangement on melting with an Al coordination change from octahedral to tetrahedral. The structure does not change appreciably with temperature in the stable and supercooled liquid. Implications of these results are discussed in connection with the solidification of aluminum oxide. {copyright} {ital 1997} {ital The American Physical Society}

Ansell, S.; Beno, M.A.; Price, D.L.; Saboungi, M. [Argonne National Laboratory, Argonne, Illinois 60439 (United States)] [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Krishnan, S.; Weber, J.R.; Felten, J.J.; Nordine, P.C. [Containerless Research, Inc., Evanston, Illinois 60201 (United States)] [Containerless Research, Inc., Evanston, Illinois 60201 (United States)

1997-01-01

446

Oxidative Stress and Diabetic Retinopathy  

PubMed Central

Oxygen metabolism is essential for sustaining aerobic life, and normal cellular homeostasis works on a fine balance between the formation and elimination of reactive oxygen species (ROS). Oxidative stress, a cytopathic consequence of excessive production of ROS and the suppression of ROS removal by antioxidant defense system, is implicated in the development of many diseases, including Alzheimer's disease, and diabetes and its complications. Retinopathy, a debilitating microvascular complication of diabetes, is the leading cause of acquired blindness in developed countries. Many diabetes-induced metabolic abnormalities are implicated in its development, and appear to be influenced by elevated oxidative stress; however the exact mechanism of its development remains elusive. Increased superoxide concentration is considered as a causal link between elevated glucose and the other metabolic abnormalities important in the pathogenesis of diabetic complications. Animal studies have shown that antioxidants have beneficial effects on the development of retinopathy, but the results from very limited clinical trials are somewhat ambiguous. Although antioxidants are being used for other chronic diseases, controlled clinical trials are warranted to investigate potential beneficial effects of antioxidants in the development of retinopathy in diabetic patients. PMID:17641741

Kowluru, Renu A.; Chan, Pooi-See

2007-01-01

447

Atmospheric oxidation mechanism of chlorobenzene.  

PubMed

The atmospheric oxidation mechanism of chlorobenzene (CB) initiated by the OH radicals is investigated at M06-2X/6-311++G(2df, 2p) and ROCBS-QB3 levels. The oxidation is initiated by OH addition to the ortho (?50%), para (?33%) and meta (?17%) positions, forming CB-OH adducts as R2, R3, and R4; while the ipso-addition is negligible (?0.2%). The reactions of the CB-OH adducts with the atmospheric oxygen are further investigated in detail by coupling the unimolecular reaction rate theory calculations with master-equation (RRKM-ME). The CB-OH adducts react with O2 either by irreversible H-abstraction to form chlorophenol and HO2 or by reversible additions to form CB-OH-O2 radicals, which subsequently cyclize to bicyclic radicals. RRKM-ME calculations show that the addition reactions of CB-OH and O2 at the atmospheric pressure are close to but not yet reach their high-pressure-limits. The RRKM-ME simulations predict the yields of 93%, 38%, and 74% for ortho-, meta- and para-chlorophenols from the reactions of O2 with R2, R3 and R4, being lower than their high-pressure-limit yields of 95%, 48%, an 80%, respectively. Overall, the yield of chlorophenols is determined as 72% at the atmospheric pressure. PMID:24997963

Wu, Runrun; Wang, Sainan; Wang, Liming

2014-09-01

448

Tape casting of magnesium oxide.  

SciTech Connect

A tape casting procedure for fabricating ceramic magnesium oxide tapes has been developed as a method to produce flat sheets of sintered MgO that are thin and porous. Thickness of single layer tapes is in the range of 200-400 {micro}m with corresponding surface roughness values in the range of 10-20 {micro}m as measured by laser profilometry. Development of the tape casting technique required optimization of pretreatment for the starting magnesium oxide (MgO) powder as well as a detailed study of the casting slurry preparation and subsequent heat treatments for sintering and final tape flattening. Milling time of the ceramic powder, plasticizer, and binder mixture was identified as a primary factor affecting surface morphology of the tapes. In general, longer milling times resulted in green tapes with a noticeably smoother surface. This work demonstrates that meticulous control of the entire tape casting operation is necessary to obtain high-quality MgO tapes.

Ayala, Alicia; Corral, Erica L.; Loehman, Ronald E.; Bencoe, Denise Nora; Reiterer, Markus; Shah, Raja A.

2008-02-01

449

Water defluoridation by aluminium oxide-manganese oxide composite material.  

PubMed

In this study, aluminium oxide-manganese oxide (AOMO) composite material was synthesized, characterized, and tested for fluoride removal in batch experiments. AOMO was prepared from manganese(II) chloride and aluminium hydroxide. The surface area of AOMO was found to be 30.7m2/g and its specific density was determined as 2.78 g/cm3. Detailed investigation of the adsorbent by inductively coupled plasma-optical emission spectrometry, inductively coupled plasma-mass spectrometry, and ion chromatography (for sulphate only) showed that it is composed of Al, Mn, SO4, and Na as major components and Fe, Si, Ca, and Mg as minor components. Thermogravimetric analysis was used to study the thermal behaviour of AOMO. X-ray diffraction analysis showed that the adsorbent is poorly crystalline. The point of zero charge was determined as 9.54. Batch experiments (by varying the proportion of MnO, adsorbent dose, contact time, initial F concentration, and raw water pH) showed that fluoride removal efficiency ofAOMO varied significantly with percentage of MnO with an optimum value of about I11% of manganese oxide in the adsorbent. The optimum dose of the adsorbent was 4 g/L which corresponds to the equilibrium adsorption capacity of 4.8 mg F-/g. Both the removal efficiency and adsorption capacity showed an increasing trend with an increase in initial fluoride concentration of the water. The pH for optimum fluoride removal was found to be in the range between 5 and 7. The adsorption data were analysed using the Freundlich, Langmuir, and Dubinirn-Radushkevich models. The minimum adsorption capacity obtained from the non-linear Freundlich isotherm model was 4.94 mg F-/g and the maximum capacity from the Langmuir isotherm method was 19.2mg F-/g. The experimental data of fluoride adsorption on AOMO fitted well to the Freundlich isotherm model. Kinetic studies showed that the adsorption is well described by a non-linear pseudo-second-order reaction model with an average rate constant of 3.1 x 10(-2) g/min mg. It is concluded that AOMO is a highly promising adsorbent for the removal of excess fluoride from drinking water. PMID:24956783

Alemu, Sheta; Mulugeta, Eyobel; Zewge, Feleke; Chandravanshi, Bhagwan Singh

2014-08-01

450

Hafnium oxide and hafnium aluminum oxide for CMOS applications  

NASA Astrophysics Data System (ADS)

The continued scaling of the CMOS gate dielectric to its fundamental limit governed by the large gate leakage current requires the introduction of high-k material for sub-100-nm technology nodes. This dissertation research deals with the physical and electrical properties of a promising high-k candidate, hafnium oxide, as a gate dielectric for CMOS applications. Hafnium oxide made by the Jet-Vapor-Deposition process shows very promising properties in terms of surface roughness, dielectric constant, and energy bandgap, but there are also severe challenges, such as low crystallization temperature, high charge trapping probability, and low channel mobility, which have been studied in detail in this thesis. We have found that the crystallization of HfO2 could result in a significant increase of the leakage current. This problem has been solved by adding Al in the HfO2 film. The impacts of Al inclusion in HfO 2 film on crystallization temperature, bandgap energy, and dielectric constant have been investigated. Considering the trade-off among the crystallization temperature, bandgap energy, and dielectric constant, we have concluded that the optimum concentration is about 30% Al for conventional self-aligned CMOS gate processing technology. The charge trapping properties of ultra-thin HfO2 in metal-oxide-silicon capacitors during constant voltage stress have also been investigated. The effects of stress voltage, substrate type, annealing temperature, and gate electrode have been studied in detail, and reported in this dissertation. Accurate measurements and degradation mechanisms of the channel mobility for MOSFETs with HfO2 as the gate dielectric have been systemetically studied. The error in mobility extraction caused by a high density of interface traps for a MOSFET with high-k gate dielectric has been analyzed, and a new method to correct this error has been proposed. Other sources of error in mobility extraction, including gate leakage current, channel resistance, and contact resistance for a MOSFET with ultra-thin high-k dielectric have also been investigated and reported in this thesis. Based on the accurately measured channel mobility, we have analyzed the degradation mechanisms of channel mobility for a MOSFET with HfO2 as the gate dielectric. The mobility degradation due to Coulomb scatting arising from interface trapped charges, and that due to remote soft optical phonon scattering are discussed.

Zhu, Wenjuan

451

Nitrogen dioxide oxidizes mitochondrial cytochrome c  

PubMed Central

We previously reported that high micromolar concentrations of nitric oxide were able to oxidize mitochondrial cytochrome c at physiological pH, producing nitroxyl anion (Sharpe and Cooper, 1998 Biochem. J. 332, 9–19). However, the subsequent re-evaluation of the redox potential of the NO/NO- couple suggests that this reaction is thermodynamically unfavored. We now show that the oxidation is oxygen-concentration dependent and non stoichiometric. We conclude that the effect is due to an oxidant species produced during the aerobic decay of nitric oxide to nitrite and nitrate. The species is most probably nitrogen dioxide, NO2• a well-known biologically active oxidant. A simple kinetic model of NO autoxidation is able to explain the extent of cytochrome c oxidation assuming a rate constant of 3 × 106 M-1 s-1 for the reaction of NO2• with ferrocytochrome c. The importance of NO2• was confirmed by the addition of scavengers such as urate and ferrocyanide. These convert NO2• into products (urate radical and ferricyanide) that rapidly oxidize cytochrome c and hence greatly enhance the extent of oxidation observed. The present study does not support the previous hypothesis that NO and cytochrome c can generate appreciable amounts of nitroxyl ions (NO- or HNO) or of peroxynitrite. PMID:22101009

Silkstone, Rebecca S.; Mason, Maria G.; Nicholls, Peter; Cooper, Chris E.

2012-01-01

452

OXIDANTS AND THE PATHOGENESIS OF LUNG DISEASES  

PubMed Central

The increasing number of population-based and epidemiological associations between oxidant pollutant exposures and cardiopulmonary disease exacerbation, decrements in pulmonary function, and mortality underscores the important detrimental effects of oxidants on public health. Because inhaled oxidants initiate a number of pathologic processes, including inflammation of the airways which may contribute to the pathogenesis and/or exacerbation of airways disease, it is critical to understand the mechanisms through which exogenous and endogenous oxidants interact with molecules in the cells, tissues, and epithelial lining fluid (ELF) of the lung. Furthermore, it is clear that inter-individual variation in response to a given exposure also exists across an individual lifetime. Because of the potential impact that oxidant exposures may have on reproductive outcomes and infant, child, and adult health, identification of the intrinsic and extrinsic factors that may influence susceptibility to oxidants remains an important issue. In this review, we discuss mechanisms of oxidant stress in the lung, the role of oxidants in lung disease pathogenesis and exacerbation (e.g. asthma, COPD, and ARDS), and the potential risk factors (e.g. age, genetics) for enhanced susceptibility to oxidant-induced disease. PMID:18774381

Ciencewicki, Jonathan; Trivedi, Shweta; Kleeberger, Steven R.

2009-01-01

453

Cerium and yttrium oxide nanoparticles are neuroprotective  

SciTech Connect

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

Schubert, David [Salk Institute, 10010 N. Torrey Pines Rd., La Jolla, CA 92037 (United States)]. E-mail: schubert@salk.edu; Dargusch, Richard [Salk Institute, 10010 N. Torrey Pines Rd., La Jolla, CA 92037 (United States); Raitano, Joan [Columbia University, Departments of Applied Physics and Applied Mathematics, 1136 Mudd, MC 4701, New York, NY 10027 (United States); Chan, S.-W. [Columbia University, Departments of Applied Physics and Applied Mathematics, 1136 Mudd, MC 4701, New York, NY 10027 (United States)

2006-03-31

454

Oxidant Sensing by Reversible Disulfide Bond Formation*  

PubMed Central

Maintenance of the cellular redox balance is crucial for cell survival. An increase in reactive oxygen, nitrogen, or chlorine species can lead to oxidative stress conditions, potentially damaging DNA, lipids, and proteins. Proteins are very sensitive to oxidative modifications, particularly methionine and cysteine residues. The reversibility of some of these oxidative protein modifications makes them ideally suited to take on regulatory roles in protein function. This is especially true for disulfide bond formation, which has the potential to mediate extensive yet fully reversible structural and functional changes, rapidly adjusting the protein's activity to the prevailing oxidant levels. PMID:23861395

Cremers, Claudia M.; Jakob, Ursula

2013-01-01

455

Removal of phosphate by aluminum oxide hydroxide.  

PubMed

The development and manufacture of an adsorbent to remove phosphate ion for the prevention of eutrophication in lakes are very important. The characteristics of phosphate adsorption onto aluminum oxide hydroxide were investigated to estimate the adsorption isotherms, the rate of adsorption, and the selectivity of adsorption. Phosphate was easily adsorbed onto aluminum oxide hydroxide, because of the hydroxyl groups. The adsorption of phosphate onto aluminum oxide hydroxide was influenced by pH in solution: the amount adsorbed was greatest at pH 4, ranging with pH from 2 to 9. The optimum pH for phosphate removal by aluminum oxide hydroxide is 4. The selectivity of phosphate adsorption onto aluminum oxide hydroxide was evaluated based on the amount of phosphate ion adsorbed onto aluminum oxide hydroxide from several anion complex solutions. It is phosphate that aluminum oxide hydroxide can selectively adsorb. The selectivity of phosphate onto aluminum oxide hydroxide was about 7000 times that of chloride. This result indicated that the hydroxyl groups on aluminum oxide hydroxide have selective adsorptivity for phosphate and could be used for the removal of phosphate from seawater. PMID:16256465

Tanada, Seiki; Kabayama, Mineaki; Kawasaki, Naohito; Sakiyama, Toru; Nakamura, Takeo; Araki, Mamiko; Tamura, Takamichi

2003-01-01

456

Nitrogen dioxide oxidizes mitochondrial cytochrome c.  

PubMed

We previously reported that high micromolar concentrations of nitric oxide were able to oxidize mitochondrial cytochrome c at physiological pH, producing nitroxyl anion (Sharpe and Cooper, 1998 Biochem. J. 332, 9-19). However, the subsequent re-evaluation of the redox potential of the NO/NO(-) couple suggests that this reaction is thermodynamically unfavored. We now show that the oxidation is oxygen-concentration dependent and non stoichiometric. We conclude that the effect is due to an oxidant species produced during the aerobic decay of nitric oxide to nitrite and nitrate. The species is most probably nitrogen dioxide, NO(2)(•) a well-known biologically active oxidant. A simple kinetic model of NO autoxidation is able to explain the extent of cytochrome c oxidation assuming a rate constant of 3×10(6)M(-1)s(-1) for the reaction of NO(2)(•) with ferrocytochrome c. The importance of NO(2)(•) was confirmed by the addition of scavengers such as urate and ferrocyanide. These convert NO(2)(•) into products (urate radical and ferricyanide) that rapidly oxidize cytochrome c and hence greatly enhance the extent of oxidation observed. The present study does not support the previous hypothesis that NO and cytochrome c can generate appreciable amounts of nitroxyl ions (NO(-) or HNO) or of peroxynitrite. PMID:22101009

Silkstone, Rebecca S; Mason, Maria G; Nicholls, Peter; Cooper, Chris E

2012-01-01

457

Photoredox laser chemistry of transition metal oxides  

NASA Astrophysics Data System (ADS)

We describe two-color laser excitation of tungsten oxide in ambient air to effect a fully reversible photoredox cycle. One color is infrared, apparently functioning as heat, and the other is visible or shorter wavelength, but not necessarily super bandgap, apparently supplying electronic excitation. In the case of either tungsten oxide or molybdenum oxide, the process can be monitored using a very strong set of Raman spectroscopic features. This process could find application in optical data storage and may be a generally useful strategy for manipulating transition metal oxides.

Osman, J. M.; Bussjager, R. J.; Nash, F.; Chaiken, J.; Villarica, R. M.

458

Deposition rates of oxidized iron on Mars  

NASA Technical Reports Server (NTRS)

The reddened oxidized surface of Mars is indicative of temporal interactions between the Martian atmosphere and its surface. During the evolution of the Martian regolith, primary ferromagnesian silicate and sulfide minerals in basaltic rocks apparently have been oxidized to secondary ferric-bearing assemblages. To evaluate how and when such oxidized deposits were formed on Mars, information about the mechanisms and rates of chemical weathering of Fe(2+)-bearing minerals has been determined. In this paper, mechanisms and rates of deposition of ferric oxide phases on the Martian surface are discussed.

Burns, R. G.

1993-01-01

459

The oxidative dehydrogenation of ethane with nitrous oxide by molybdenum oxide supported by silica gel  

E-print Network

. Ethylene typically comprised 80% of the product gases for 100 min of reaction. Although the initial rate for the formation of C2Hq on a virgin catalyst was high, the reaction was inhibited by coke and QH , and eventually a steady state was observed...) CpHSOH dr compo. , i t i on 47 INTRODUCTION One important problem that confronts the petrochemical industry today is the selective conversion of alkanes into alkenes. Although the prose-s of oxidative dehydrogenation (OXD) (&as been wrdely imple...

Ward, Mark Branham

2012-06-07

460

Room temperature aerobic oxidation of amines by a nanocrystalline ruthenium oxide pyrochlore nafion composite catalyst.  

PubMed

The aerobic oxidation of primary amines to their respective nitriles has been carried out at room temperature using a highly reusable nanocrystalline ruthenium oxide pyrochlore Nafion composite catalyst (see figure). PMID:22489045

Venkatesan, Shanmuganathan; Kumar, Annamalai Senthil; Lee, Jyh-Fu; Chan, Ting-Shan; Zen, Jyh-Myng

2012-05-14

461

Simple self-gettering differential-pump for minimizing source oxidation in oxide-MBE environment  

SciTech Connect

Source oxidation of easily oxidizing elements such as Ca, Sr, Ba, and Ti in an oxidizing ambient leads to their flux instability and is one of the biggest problems in the multielemental oxide molecular beam epitaxy technique. Here, the authors report a new scheme that can completely eliminate the source oxidation problem: a self-gettering differential pump using the source itself as the pumping medium. The pump simply comprises a long collimator mounted in front of the source in extended port geometry. With this arrangement, the oxygen partial pressure near the source was easily maintained well below the source oxidation regime, resulting in a stabilized flux, comparable to that of an ultrahigh-vacuum environment. Moreover, this pump has a self-feedback mechanism that allows a stronger pumping effectiveness for more easily oxidizing elements, which is a desired property for eliminating the source oxidation problem.

Kim, Yong-Seung; Bansal, Namrata; Oh, Seongshik [Department of Physics and Astronomy, Rutgers, State University of New Jersey, 136 Frelinghuysen Road, Piscataway, New Jersey 08854 (United States); Department of Electrical and Computer Engineering, Rutgers, State University of New Jersey, 94 Brett Road, Piscataway, New Jersey 08854 (United States)

2011-07-15

462

Kinetics and Mechanism of Oxidative Dehydrogenation of Propane on Vanadium, Molybdenum, and Tungsten Oxides  

E-print Network

Kinetics and Mechanism of Oxidative Dehydrogenation of Propane on Vanadium, Molybdenum catalysts confirmed that oxidative dehydrogenation of propane occurs via similar pathways, which involve for propane dehydrogenation and for propene combustion increase in the sequence VOx/ZrO2

Iglesia, Enrique

463

The oxidation of carbon monoxide using a tin oxide catalyst  

NASA Astrophysics Data System (ADS)

This paper outlines some of the steps involved in the development by the United Kingdom Atomic Energy Authority (UKAEA) of a catalytic device for the recombination of carbon monoxide and oxygen in a CO2 laser system. It contrasts the differences between CO oxidation for air purification and for laser environmental control, but indicates that there are similarities between the physical specifications. The principal features of catalytic devices are outlined and some experimental work described. This includes measurements concerning the structure and mechanical properties of the artifact, the preparation of the catalyst coating and its interaction with the gaseous environment. The paper concludes with some speculation about the method by which the reaction actually occurs.

Sampson, Christopher F.; Gudde, Nicholas J.

1987-04-01

464

Indium Tin Oxide Resistor-Based Nitric Oxide Microsensors  

NASA Technical Reports Server (NTRS)

A sensitive resistor-based NO microsensor, with a wide detection range and a low detection limit, has been developed. Semiconductor microfabrication techniques were used to create a sensor that has a simple, robust structure with a sensing area of 1.10 0.99 mm. A Pt interdigitated structure was used for the electrodes to maximize the sensor signal output. N-type semiconductor indium tin oxide (ITO) thin film was sputter-deposited as a sensing material on the electrode surface, and between the electrode fingers. Alumina substrate (250 m in thickness) was sequentially used for sensor fabrication. The resulting sensor was tested by applying a voltage across the two electrodes and measuring the resulting current. The sensor was tested at different concentrations of NO-containing gas at a range of temperatures. Preliminary results showed that the sensor had a relatively high sensitivity to NO at 450 C and 1 V. NO concentrations from ppm to ppb ranges were detected with the low limit of near 159 ppb. Lower NO concentrations are being tested. Two sensing mechanisms were involved in the NO gas detection at ppm level: adsorption and oxidation reactions, whereas at ppb level of NO, only one sensing mechanism of adsorption was involved. The NO microsensor has the advantages of high sensitivity, small size, simple batch fabrication, high sensor yield, low cost, and low power consumption due to its microsize. The resistor-based thin-film sensor is meant for detection of low concentrations of NO gas, mainly in the ppb or lower range, and is being developed concurrently with other sensor technology for multispecies detection. This development demonstrates that ITO is a sensitive sensing material for NO detection. It also provides crucial information for future selection of nanostructured and nanosized NO sensing materials, which are expected to be more sensitive and to consume less power.

Xu, Jennifer C.; Hunter, Gary W.; Gonzalez, Jose M., III; Liu, Chung-Chiun

2012-01-01

465

Solvent free synthesis of chalcone and flavanone over zinc oxide supported metal oxide catalysts  

Microsoft Academic Search

Liquid phase Claisen–Schmidt condensation between 2?-hydroxyacetophenone and benzaldehyde to form 2?-hydroxychalcone, followed by intramolecular cyclisation to form flavanone was carried out over zinc oxide supported metal oxide catalysts under solvent free condition. The reaction was carried out over ZnO supported MgO, BaO, K2O and Na2O catalysts with 0.2g of each catalyst at 140°C for 3h. Magnesium oxide impregnated zinc oxide

S. Saravanamurugan; M. Palanichamy; Banumathi Arabindoo; V. Murugesan

2005-01-01

466

Process for the separation of sulfur oxides from a gaseous mixture containing sulfur oxides and oxygen  

SciTech Connect

An improved process for the separation of sulfur oxides from a gaseous mixture containing sulfur oxides and oxygen is disclosed. The gaseous mixture is contacted with a solid sulfur oxide acceptor comprising copper, copper oxide, or a mixture thereof dispersed on a carrier material in combination with a platinum group metal component and a component selected from the group consisting of rhenium, germanium and tin.

Derosset, A.J.; Ginger, E.A.

1980-12-23

467

Aqueous colloids of graphene oxide nanosheets by exfoliation of graphite oxide without ultrasonication  

Microsoft Academic Search

.  Aqueous colloids of graphene oxide nanosheets were produced from exfoliation of graphite oxide using a magnetic stirrer and\\u000a heat treatment in the absence of ultrasonication. Laser particle measurements showed that the particle size distribution of\\u000a graphite oxide dispersed in de-ionized water was significantly influenced by treatment time indicating an increasing exfoliation\\u000a level of graphite oxide. Atomic force microscopy (AFM) confirmed

TIAN-YOU ZHANG; DONG ZHANG

468

Oxide formation at the initial stages of oxidation of a eutectic Pb-Bi alloy  

NASA Astrophysics Data System (ADS)

The results of electron diffraction study of the oxidation of a eutectic Pb-Bi alloy during heating at various partial oxygen pressures in the gas phase are presented. It is revealed that only the oxide phases of lead form at the initial stages of oxidation, which occurs from ?-PbO2 through intermediate oxides nPbO2 · mPbO and Pb3O4 to the ?-PbO modification.

Lyamkin, S. A.

2010-09-01

469

Catalytic oxidation of dye wastewater by metal oxide catalyst and granular activated carbon  

Microsoft Academic Search

Bench experiments were conducted to investigate the catalytic oxidation of dye wastewater by metal oxides. The catalytic oxidation was carried out in an air fluidized-bed reactor and was assisted by V2O5 as catalyst, granular activated carbon (GAC), and hydrogen peroxide. The experimental results indicated that, in the present oxidation process, both chemical and physical actions took place which are distinctly

Sheng H. Lin; Cheng L. Lai

1999-01-01

470

Spectroscopic ellipsometry characterization of electrochromic tungsten oxide and nickel oxide thin films made by sputter deposition  

Microsoft Academic Search

Electrochromic films of tungsten oxide and nickel oxide were made by reactive dc magnetron sputtering and were characterized by X-ray diffraction, Rutherford backscattering spectrometry, scanning electron microscopy, and atomic force microscopy. The optical properties were investigated in detail by spectroscopic ellipsometry and spectrophotometry, using a multiple-sample approach. The W-oxide film was modeled as a homogeneous isotropic layer, whereas the Ni-oxide

I. Valyukh; S. Green; H. Arwin; G. A. Niklasson; E. Wäckelgård; C. G. Granqvist

2010-01-01

471

Oxidation behavior of AlN in the presence of oxide and glass for thick film applications  

Microsoft Academic Search

The effect of oxides and oxide glasses on the oxidation of AlN powder and substrate was studied by thermogravimetric analysis, supplemented by XRD, optical microscopy, and EPMA. The oxidation behavior of powder mixtures of AlN and oxides or glass frits in air was dependent on the oxide species. Oxides were divided into three groups: PbO, CuO, and Bi2O3 promoted the

TAKASHI YAMAGUCHI; MAICIKO KAGEYAMA

1989-01-01

472

Unprecedented Selective Oxidation of Styrene Derivatives using a Supported Iron Oxide Nanocatalyst in Aqueous Medium  

EPA Science Inventory

Iron oxide nanoparticles supported on mesoporous silica-type materials have been successfully utilized in the aqueous selective oxidation of alkenes under mild conditions using hydrogen peroxide as a green oxidant. Catalysts could be easily recovered after completion of the reac...