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1

Persulfate Oxidation of Gasoline Compounds  

NASA Astrophysics Data System (ADS)

In situ chemical oxidation (ISCO) using persulfate is a promising remediation technology that can be potentially applied to a wide range of organic contaminants. Gasoline compounds are of particular interest because they extensively impact the soil and groundwater, and are highly persistent and toxic. In this investigation, destruction of specific gasoline compounds (benzene, toluene, ethylbenzenes, xylenes, trimethylbenzenes (TMBs) and naphthalene), and fractions (F1 and F2) by activated and inactivated persulfate was studied at the bench-scale. Aqueous phase batch reactors (25 mL) for inactivated systems employed persulfate at two concentrations (1 or 20 g/L), and activated systems were conducted with a persulfate concentration of 20 g/L. In the activated systems, the ability of hydrogen peroxide or chelated-ferrous as an activator was examined at two experimental conditions (peroxide molar ratio 0.1 and 1.0 with respect to persulfate; and citric acid chelated ferrous at 150 and 600 mg/L). All treatments and controls contained an initial gasoline concentration of approximately 25 mg/L and were run in triplicate. Sampling for gasoline compounds was conducted over <28 day reaction period. The controls showed insignificant degradation for all the gasoline compounds and fractions examined while inactivated persulfate at 1 g/L showed little (<10%) decrease in the concentration of gasoline compounds over the 28 day reaction period. Inactivated persulfate at 20 g/L demonstrated a significant decrease in the aqueous concentration of BTEX (>99%), TMB (>94%) and naphthalene (>71%). Oxidation of the F1 fraction (>94%) was more pronounced than the F2 fraction (>80%), and >93% TPH was oxidized. Use of peroxide as an activator at a molar ratio of 0.1 improved the destruction of TMBs (>99%) and naphthalene (>85%) while maintaining the high removal of BTEX (>99%) compounds. Increase in activator strength (molar ratio 1.0) decreased the destruction of xylenes (>86%) and TMBs (>81%). The decrease in concentration of all the compounds was higher for a molar ratio of 1.0 (<27%) as compared with a molar ratio of 0.1 (<11%). The activation by ferrous concentration resulted in higher oxidation of compounds (except naphthalene) as compared with unactivated or peroxide activated persulfate. 1,3,5-TMB was completed oxidized after 4 days using higher chelated ferrous concentration and after 12 days using lower chelated ferrous concentration for persulfate activation. In general, increase in chelated ferrous concentration resulted in higher oxidation of the gasoline compounds. While oxidation of F1 fraction was similar for two ferrous activation conditions, the oxidation of F2 fraction was lower when ferrous activation at 600 mg/L was employed. Use of persulfate at high dosages by itself or in combination with higher doses of chelated ferrous or optimum doses of peroxide as an activator seems to be a viable option for remediation of gasoline compounds examined in this study. Persulfate appears to be particularly effective in the oxidation of BTEX compounds, but may require ferrous activation for a complete oxidation of TMBs and peroxide activation for oxidation of naphthalene.

Sra, K.; Thomson, N.; Barker, J.

2009-05-01

2

Impact of activation methods on persulfate oxidation of methyl tert-butyl ether.  

PubMed

To provide guidance on the selection of proper persulfate processes for the remediation of MTBE contaminated groundwater, MTBE aqueous solutions were treated with three common field persulfate processes including heat activated persulfate, Fe(III)-EDTA activated persulfate and alkaline persulfate, respectively. The results were compared with MTBE oxidation by Fenton's reagent and persulfate alone at 25°C. The impact of the activating conditions on the fate of MTBE and its daughter products was investigated. Heat activation at 40°C offered the most rapid removal of MTBE and its daughter products, while Fe(III)-EDTA activation showed higher efficiency of MTBE removal but low removal efficiency of its daughter products. On the other hand, alkaline persulfate showed slower kinetics for the removal of MTBE and less accumulation of the daughter products. Furthermore, tert-butyl alcohol and acetone were observed as the main purgeable daughter products along with a small amount of tert-butyl formate in persulfate oxidation of MTBE, while tert-butyl formate, tert-butyl alcohol and acetone were the main products in Fenton oxidation. Mechanistic analysis suggests that degradation of MTBE by persulfate most likely happens via non-oxygen demand pathways, different from the dominant oxygen demand degradation pathways observed in Fenton oxidation. PMID:24246442

Deng, Dayi; Peng, Libin; Guan, Mengyun; Kang, Yuan

2014-01-15

3

Ultrasonically enhanced persulfate oxidation of polyethylene surfaces  

Microsoft Academic Search

The ultrasonically enhanced oxidation of polyethylene surfaces by potassium and ammonium persulfates is described. The use of ultrasound allows significant levels of surface modification to be achieved using these oxidizing agents under mild conditions. Changes in the water contact angle and attenuated total reflection infra-red spectra were used to follow the changes in surface chemistry. Variation of conditions such as

Fiona Keen

1996-01-01

4

Rapid persulfate oxidation predicts PAH bioavailability in soils and sediments  

Microsoft Academic Search

Persulfate oxidation was validated as a method to predict polycyclic aromatic hydrocarbon (PAH) bioavailability in soils and sediments. It was demonstrated for 14 field contaminated soils and sediments that residual PAH concentrations after a short (3 h) persulfate oxidation correspond well to residual PAH concentrations after 21 days of biodegradation. Persulfate oxidation of samples that had first been subjected to

Chiel Cuypers; Tim Grotenhuis; Jan Joziasse; Wim Rulkens

2000-01-01

5

Rapid persulfate oxidation predicts PAH bioavailability in soils and sediments  

SciTech Connect

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

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

2000-05-15

6

Liquid-phase catalytic oxidation of CO by ammonium persulfate  

SciTech Connect

The catalytic oxidation of carbon monoxide in aqueous solutions is investigated. The abilities of ammonium persulfate, palladium hydroxide, and silver oxide to force the oxidation are discussed. The rates for these reactions are displayed graphically. The reaction rates as a function of the concentrations of the above-mentioned reactants are determined. An excess of persulfate is found to oxidize Pd(II) to Pd(IV), and this produces a reduction in the rate of CO oxidation. The oxidation of CO is preceeded in the reaction by the interaction of the persulfate with the metal catalyst.

Golodov, V.A.; Abilov, M.T.; Sokol'skii, D.V.

1984-01-01

7

Degradation of volatile organic compounds with thermally activated persulfate oxidation  

Microsoft Academic Search

This study investigated the extent and treatability of the degradation of 59 volatile organic compounds (VOCs) listed in the EPA SW-846 Method 8260B with thermally activated persulfate oxidation. Data on the degradation of the 59 VOCs (in mixture) reacted with sodium persulfate in concentrations of 1gl?1 and 5gl?1 and at temperatures of 20°C, 30°C, and 40°C were obtained. The results

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

2005-01-01

8

Release of chromium from soils with persulfate chemical oxidation.  

PubMed

An important part of the evaluation of the effectiveness of persulfate in situ chemical oxidation (ISCO) for treating organic contaminants is to identify and understand its potential impact on metal co-contaminants in the subsurface. Chromium is a redox-sensitive and toxic metal the release of which poses considerable risk to human health. The objective of this study was to investigate the impact of persulfate chemical oxidation on the release of chromium from three soils varying in physical-chemical properties. Soils were treated with unactivated and activated persulfate [activated with Fe(II), Fe(II)-EDTA, and alkaline pH] at two different concentrations (i.e., 41 mM and 2.1 mM persulfate) for 48 h and 6 months and were analyzed for release of chromium. Results show that release of chromium with persulfate chemical oxidation depends on the soil type and the activation method. Sandy soil with low oxidant demand released more chromium compared to soils with high oxidant demand. More chromium was released with alkaline pH activation. Alkaline pH and high Eh conditions favor oxidation of Cr(III) to Cr(VI), which is the main mechanism of release of chromium with persulfate chemical oxidation. Unactivated and Fe(II)-activated persulfate decreased pH and at low pH in absence of EDTA chromium release is not a concern. These results indicate that chromium release can be anticipated based on the given site and treatment conditions, and ISCO system can be designed to minimize potential chromium release when treating soils and groundwater contaminated with both organic and metal contaminants. PMID:24028318

Kaur, Kawalpreet; Crimi, Michelle

2014-01-01

9

Microwave-enhanced persulfate oxidation to treat mature landfill leachate.  

PubMed

Microwave oxidation process (MOP) was evaluated for treatment of landfill leachate. Kinetics of persulfate oxidation in MOP, effects of pH and persulfate doses on fates of derivative organic acids, and the energy cost of MOP were evaluated. The results showed that total organic carbon (TOC) removal of 79.4%, color removal of 88.4%, and UV254 removal of 77.1% were reached at MOP 550W/85°C within 30min. The kinetics of oxidation by MOP followed the first-order reaction. For a given persulfate dose, the reaction rate increased with the microwave power setting (775W>550W>325W>128W) with reaction rate constants ranging from 10(-5) to 10(-2)min(-1). The adverse effects on reaction rates under higher microwave power settings and high persulfate doses are plausibly caused by excessive persulfate oxidation and self-scavenging termination of free radicals. During the MOP treatment, TOC/COD ratio dropped with time and an 86.7% reduction in TOC/COD ratio after 120min at pH 7. Oxalic acid was the major derivative and its concentrations were higher under acidic conditions. Malic, lactic, and acetic acids were formed and soon degraded, and the solution pH has an insignificant effect on their fates. The energy cost of MOP (USD$6.03/m(3)) is essentially similar to that of conventional heating oxidation (CHO) (USD$6.10/m(3)). PMID:25463221

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

2015-03-01

10

Intensification of sonochemical degradation of ammonium perfluorooctanoate by persulfate oxidant.  

PubMed

Ammonium perfluorooctanoate (APFO) is an emerging environmental pollutant attracting significant attention due to its global distribution, high persistence, and bioaccumulation properties. The decomposition of APFO in aqueous solution with a combination of persulfate oxidant and ultrasonic irradiation was investigated. The effects of operating parameters, such as ultrasonic power, persulfate concentration, APFO concentration, and initial media pH on APFO degradation were discussed. In the absence of persulfate, 35.5% of initial APFO in 46.4 ?mol/L solution under ultrasound irradiation, was decomposed rapidly after 120 min with the defluorination ratio reaching 6.73%. In contrast, when 10 mmol/L persulfate was used, 51.2% of initial APFO (46.4 ?mol/L) was decomposed and the defluorination ratio reached 11.15% within 120 min reaction time. Enhancement of the decomposition of APFO can be explained by acceleration of substrate decarboxylation, induced by sulfate radical anions formed from the persulfate during ultrasonic irradiation. The SO4(-•)/APFO reactions at the bubble-water interface appear to be the primary pathway for the sonochemical degradation of the perfluorinated surfactants. PMID:24139324

Hao, Feifei; Guo, Weilin; Wang, Anqi; Leng, Yanqiu; Li, Helian

2014-03-01

11

Evaluation of persulfate oxidative wet scrubber for removing BTEX gases.  

PubMed

Soil vapor extraction (SVE) coupled with air sparging of groundwater is a method commonly used to remediate soil and groundwater contaminated with volatile organic petroleum contaminants such as gasoline. These hazardous contaminants are mainly attributable to the compounds-benzene, toluene, ethylbenzene, and xylenes (known collectively as BTEX). Exhaust gas from SVE may contain BTEX, and therefore must be treated before being discharged. This study evaluated the use of iron-activated persulfate chemical oxidation in conjunction with a wet scrubbing system, i.e., a persulfate oxidative scrubber (POS) system, to destroy BTEX gases. The persulfate anions can be activated by citric acid (CA) chelated Fe(2+) to generate sulfate radicals (SO(4)(*-), E degrees =2.4V), which may rapidly degrade BTEX in the aqueous phase and result in continuous destruction of the BTEX gases. The results show that persulfate activation occurred as a result of continuous addition of the citric acid chelated Fe(2+) activator, which readily oxidized the dissolved BTEX. Based on initial results from the aqueous phase, a suitable Fe(2+)/CA molar ratio of 5/3 was determined and used to initiate activation in the subsequent POS system tests. In the POS system, using persulfate as a scrubber solution and with activation by injecting Fe(2+)/CA activators under two testing conditions, varying iron concentrations and pumping rates, resulted in an approximate 50% removal of BTEX gases. During the course of the tests which in corporate activation, a complete destruction of BTEX was achieved in the aqueous phase. It is noted that no removal of BTEX occurred in the control tests which did not include activation. The results of this study would serve as a reference for future studies into the practical chemical oxidation of waste gas streams. PMID:18829165

Liang, Chenju; Chen, Yan-Jyun; Chang, Keng-Jung

2009-05-30

12

Identification of persulfate oxidation products of polycyclic aromatic hydrocarbon during remediation of contaminated soil.  

PubMed

The extent of PAH transformation, the formation and transformation of reaction byproducts during persulfate oxidation of polycyclic aromatic hydrocarbons (PAHs) in coking plant soil was investigated. Pre-oxidation analyses indicated that oxygen-containing PAHs (oxy-PAHs) existed in the soil. Oxy-PAHs including 1H-phenalen-1-one, 9H-fluoren-9-one, and 1,8-naphthalic anhydride were also produced during persulfate oxidation of PAHs. Concentration of 1,8-naphthalic anhydride at 4h in thermally activated (50°C) persulfate oxidation (TAPO) treatment increased 12.7 times relative to the oxidant-free control. Additionally, the oxy-PAHs originally present and those generated during oxidation can be oxidized by unactivated or thermally activated persulfate oxidation. For example, 9H-fluoren-9-one concentration decreased 99% at 4h in TAPO treatment relative to the control. Thermally activated persulfate resulted in greater oxy-PAHs removal than unactivated persulfate. Overall, both unactivated and thermally activated persulfate oxidation of PAH-contaminated soil reduced PAH mass, and oxidized most of the reaction byproducts. Consequently, this treatment process could limit environmental risk related to the parent compound and associated reaction byproducts. PMID:24862467

Liao, Xiaoyong; Zhao, Dan; Yan, Xiulan; Huling, Scott G

2014-07-15

13

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

Microsoft Academic Search

In situ chemical oxidation with persulfate anion (S2O82-) is a viable technique for remediation of groundwater contaminants such as trichloroethylene (TCE). An accelerated reaction using S2O82- to destroy TCE can be achieved via chemical activation with ferrous ion to generate sulfate radicals (SO4-·)(E°=2.6V). The column study presented here simulates persulfate oxidation of TCE in porous media (glass beads and a

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

2008-01-01

14

Defluorination of aqueous perfluorooctanesulfonate by activated persulfate oxidation.  

PubMed

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

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

2013-01-01

15

Modeling the oxidation kinetics of sono-activated persulfate's process on the degradation of humic acid.  

PubMed

Ultrasound degradation of humic acid has been investigated in the presence of persulfate anions at ultrasonic frequency of 40kHz. The effects of persulfate anion concentration, ultrasonic power input, humic acid concentration, reaction time, solution pH and temperature on humic acid removal efficiency were studied. It is found that up to 90% humic acid removal efficiency was achieved after 2h reaction. In this system, sulfate radicals (SO4(-)) were considered to be the mainly oxidant to mineralize humic acid while persulfate anion can hardly react with humic acid directly. A novel kinetic model based on sulfate radicals (SO4(-)) oxidation was established to describe the humic acid mineralization process mathematically and chemically in sono-activated persulfate system. According to the new model, ultrasound power, persulfate dosage, solution pH and reaction temperature have great influence on humic acid degradation. Different initial concentration of persulfate anions and humic acid, ultrasonic power, initial pH and reaction temperature have been discussed to valid the effectiveness of the model, and the simulated data showed new model had good agreement with the experiments data. PMID:25465096

Wang, Songlin; Zhou, Ning; Wu, Si; Zhang, Qi; Yang, Zhi

2014-10-30

16

Measurement of dissolved organic carbon by wet chemical oxidation with persulfate: influence of chloride concentration and reagent volume  

Microsoft Academic Search

The influence of chloride content and reagent volume on the analysis of dissolved organic carbon by wet chemical oxidation with persulfate was evaluated. A strong hyperbolic relationship was found between measured DOC concentration and volume of persulfate added for oxidation in both marine and artificially chlorinated (NaCl) freshwater samples. Freshwater samples showed no such relationship. Precision of measured DOC concentrations

James H. McKenna; Peter H. Doering

1995-01-01

17

Total dissolved nitrogen analysis: comparisons between the persulfate, UV and high temperature oxidation methods  

Microsoft Academic Search

We compared the persulfate (PO), ultraviolet (UV), and high temperature oxidation (HTO) methods used to analyze total dissolved nitrogen (TDN) concentrations in aquatic samples to determine whether the three methods differed in terms of standard parameters (blanks, limits of detection and linearity, and precision) or in oxidation efficiency of standard compounds and field samples of varying salinity. The TDN concentrations

Deborah A. Bronk; Michael W. Lomas; Patricia M. Glibert; Karyn J. Schukert; Marta P. Sanderson

2000-01-01

18

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 ...

19

Kinetics of heat-assisted persulfate oxidation of methyl tert-butyl ether (MTBE)  

Microsoft Academic Search

The kinetics of heat-assisted persulfate oxidation of methyl tert-butyl ether (MTBE) in aqueous solutions at various pH, temperature, oxidant concentration and ionic strength levels was studied. The MTBE degradation was found to follow a pseudo-first-order decay model. The pseudo-first-order rate constants of MTBE degradation by persulfate (31.5 mM) at pH 7.0 and ionic strength 0.11 M are ?0.13×10?4, 0.48×10?4, 2.4×10?4

Kun-Chang Huang; Richard A Couttenye; George E Hoag

2002-01-01

20

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

EPA Science Inventory

The goal of this study was to assess the oxidation of NAPL in soil, 30% of which were composed of chlorinated ethanes and ethenes, using catalyzed hydrogen peroxide (CHP), activated persulfate (AP), and H2O2?persulfate (HP) co-amendment systems. Citrate, a buffer and iron ligand,...

21

Influence of pH on persulfate oxidation of TCE at ambient temperatures  

Microsoft Academic Search

In situ chemical oxidation (ISCO) is a technology used for groundwater remediation. This laboratory study investigated the use of the oxidant sodium persulfate for the chemical oxidation of trichloroethylene (TCE) at near ambient temperatures (10, 20 and 30°C) to determine the influence of pH (pH=4, 7 and 9) on the reaction rate (i.e., pseudo-first-order rate constants) over the range of

Chenju Liang; Zih-Sin Wang; Clifford J. Bruell

2007-01-01

22

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

Microsoft Academic Search

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

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

2004-01-01

23

kinetics and mechanism of the oxidation of uranium(iv) by persulfate ions in perchloric acid solutions  

SciTech Connect

The kinetics of the oxidation of uranium(IV) by persulfate ions in perchloric acid solutions was studied by a spectrophotometric method. It was established that the oxidation of uranium(IV) ions occurs along three pathways: directly by S/sub 2/O /SUP 2/8/ /sup -/ ions, by products of their thermal decomposition, and intramolecularly in a persulfate complex. It was shown that the contribution of each of the three pathways to the overall rate of oxidation of uranium(IV) depends on the initial reagent concentrations, the hydrogen ion concentration, and the temperature. The activation energies of the oxidation of uranium(IV) directly by persulfate ions, by products of their thermal decomposition, as well as in a persulfate complex, were determined.

Ermakov, V.A.

1986-07-01

24

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

25

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

Microsoft Academic Search

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

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

2004-01-01

26

In situ chemical oxidation of contaminated groundwater by persulfate: decomposition by Fe(III)- and Mn(IV)-containing oxides and aquifer materials.  

PubMed

Persulfate (S2O8(2-)) is being used increasingly for in situ chemical oxidation (ISCO) of organic contaminants in groundwater, despite an incomplete understanding of the mechanism through which it is converted into reactive species. In particular, the decomposition of persulfate by naturally occurring mineral surfaces has not been studied in detail. To gain insight into the reaction rates and mechanism of persulfate decomposition in the subsurface, and to identify possible approaches for improving its efficacy, the decomposition of persulfate was investigated in the presence of pure metal oxides, clays, and representative aquifer solids collected from field sites in the presence and absence of benzene. Under conditions typical of groundwater, Fe(III)- and Mn(IV)-oxides catalytically converted persulfate into sulfate radical (SO4(•-)) and hydroxyl radical (HO(•)) over time scales of several weeks at rates that were 2-20 times faster than those observed in metal-free systems. Amorphous ferrihydrite was the most reactive iron mineral with respect to persulfate decomposition, with reaction rates proportional to solid mass and surface area. As a result of radical chain reactions, the rate of persulfate decomposition increased by as much as 100 times when benzene concentrations exceeded 0.1 mM. Due to its relatively slow rate of decomposition in the subsurface, it can be advantageous to inject persulfate into groundwater, allowing it to migrate to zones of low hydraulic conductivity where clays, metal oxides, and contaminants will accelerate its conversion into reactive oxidants. PMID:25133603

Liu, Haizhou; Bruton, Thomas A; Doyle, Fiona M; Sedlak, David L

2014-09-01

27

Oxidation Efficiency of Different Oxidants of Persulfate Method Used to Determine Total Nitrogen and Phosphorus in Solutions  

Microsoft Academic Search

Its speed, safety, and convenience have made the persulfate oxidation method popular in recent years for determining total N and P in natural water, soil solution and soil extracts. However, the compositions of the oxidizing reagent (i.e., the concentrations of K2S2O8 and NaOH in oxidizing reagent) used by different researchers varied. In this study, a standard urea solution was used

Jianbin Zhou; Zhujun Chen; Shengxiu Li

2003-01-01

28

Optimization of stabilized leachate treatment using ozone/persulfate in the advanced oxidation process.  

PubMed

The objective of this study was to investigate the performance of employing persulfate reagent in the advanced oxidation of ozone to treat stabilized landfill leachate in an ozone reactor. A central composite design (CCD) with response surface methodology (RSM) was applied to evaluate the relationships between operating variables, such as ozone and persulfate dosages, pH, and reaction time, to identify the optimum operating conditions. Quadratic models for the following four responses proved to be significant with very low probabilities (<0.0001): COD, color, NH3-N, and ozone consumption (OC). The obtained optimum conditions included a reaction time of 210 min, 30 g/m(3) ozone, 1g/1g COD0/S2O8(2-) ratio, and pH 10. The experimental results were corresponded well with predicted models (COD, color, and NH3-N removal rates of 72%, 96%, and 76%, respectively, and 0.60 (kg O3/kg COD OC). The results obtained in the stabilized leachate treatment were compared with those from other treatment processes, such as ozone only and persulfate S2O8(2-) only, to evaluate its effectiveness. The combined method (i.e., O3/S2O8(2-)) achieved higher removal efficiencies for COD, color, and NH3-N compared with other studied applications. Furthermore, the new method is more efficient than ozone/Fenton in advanced oxidation process in the treatment of the same studied leachate. PMID:23498721

Abu Amr, Salem S; Aziz, Hamidi Abdul; Adlan, Mohd Nordin

2013-06-01

29

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

30

The Persulfate Process for the Mediated Oxidation of Organic Pollutants  

NASA Astrophysics Data System (ADS)

The electrochemical treatment of effluents with conventional anodic materials is not very efficient in terms of organic pollutant oxidation and produces a large amount of oxygen. These results can be enhanced by mediated oxidation that produces stronger oxidants than oxygen which oxidize the organic pollutants. New electrode materials like, boron-doped diamond (BDD) shows a high selectivity toward organic pollutants and the oxygen is not easily produced. Consequently the contribution of mediated oxidation cannot be excluded, but probably occurs in a different way. This chapter re-examines at the light of the present knowledge the mediated oxidation with the BDD anode, tests the used mediated oxidation method, and proposes an alternative method to increase the positive contribution of this oxidation during electrochemical treatment with BDD anodes.

Vatistas, N.; Comninellis, Ch.

31

Bromate formation from bromide oxidation by the UV/persulfate process.  

PubMed

Bromate formation from bromide oxidation by the UV/persulfate process was investigated, along with changes in pH, persulfate dosages, and bromide concentrations in ultrapure water and in bromide-spiked real water. In general, the bromate formation increased with increasing persulfate dosage and bromide concentration. The bromate formation was initiated and primarily driven by sulfate radicals (SO(4)(•-)) and involved the formation of hypobromous acid/hypobromite (HOBr/OBr(-)) as an intermediate and bromate as the final product. Under the test conditions, the rate of the first step driven by SO(4)(•-) is slower than that of the second step. Direct UV photolysis of HOBr/OBr(-) to form bromate and the photolysis of bromate are insignificant. The bromate formation was similar for pH 4-7 but decreased over 90% with increasing pH from 7 to above 9. Less bromate was formed in the real water sample than in ultrapure water, which was primarily attributable to the presence of natural organic matter that reacts with bromine atoms, HOBr/OBr(-) and SO(4)(•-). The extent of bromate formation and degradation of micropollutants are nevertheless coupled processes unless intermediate bromine species are consumed by NOM in real water. PMID:22831804

Fang, Jing-Yun; Shang, Chii

2012-08-21

32

Chemical Oxidation of Complex PAH Mixtures by Base-activated Sodium Persulfate  

NASA Astrophysics Data System (ADS)

In situ chemical oxidation (ISCO) is an attractive approach for the remediation of recalcitrant soil and groundwater contaminants. One oxidant that has received significant recent attention is sodium persulfate, which has several advantages, including a relatively long lifetime in porous media, the ability to destroy a wide-range of chemical contaminants, and a high oxidation potential. In this study, we investigated the chemical mechanisms associated with base-activated persulfate oxidation of polycyclic aromatic hydrocarbons (PAHs) and assessed the applicability of persulfate to the remediation of porous media contaminated with non-aqueous phase liquid (NAPL) PAH mixtures. Batch experiments were conducted to determine the oxidation kinetics for individual PAH compounds, synthetic PAH mixtures, and manufactured gas plant (MGP) tars. Additional experiments were conducted with added surfactants (Triton X-100, Triton X-45, and Tween 80) to increase PAH mass transfer from the NAPL to the aqueous phase, and with radical scavengers (ethanol and tert-butyl alcohol) to identify the reactive species responsible for degradation. Degradation of total PAHs in the NAPL experiments was as high as 70%. The addition of surfactant increased initial PAH degradation rates, but also greatly increased the rate of base consumption, thereby reducing the overall fraction degraded. The degradation of individual PAHs within the NAPLs varied significantly, with the masses of some compounds remaining largely unchanged. The results of the radical scavenger and single PAH experiments suggest that the observed pattern of degradation in PAH mixtures is the result of a combination of mass transfer considerations and competition for radical species.

Hauswirth, S.; Miller, C. T.

2013-12-01

33

Optimization of stabilized leachate treatment using ozone/persulfate in the advanced oxidation process  

SciTech Connect

Highlights: ? Ozone and persulfate reagent (O{sub 3}/S{sub 2}O{sub 8}{sup 2-}) was used to treat stabilized leachate. ? Central composite design (CCD) with response surface methodology (RSM) was applied. ? Operating variables including ozone and persulfate dosage, pH variance, and reaction time. ? Optimum removal of COD, color, and NH{sub 3}–N was 72%, 96%, and 76%, respectively. ? A good value of ozone consumption (OC) obtained with 0.60 (kg O{sub 3}/kg COD). - Abstract: The objective of this study was to investigate the performance of employing persulfate reagent in the advanced oxidation of ozone to treat stabilized landfill leachate in an ozone reactor. A central composite design (CCD) with response surface methodology (RSM) was applied to evaluate the relationships between operating variables, such as ozone and persulfate dosages, pH, and reaction time, to identify the optimum operating conditions. Quadratic models for the following four responses proved to be significant with very low probabilities (<0.0001): COD, color, NH{sub 3}–N, and ozone consumption (OC). The obtained optimum conditions included a reaction time of 210 min, 30 g/m{sup 3} ozone, 1 g/1 g COD{sub 0}/S{sub 2}O{sub 8}{sup 2-} ratio, and pH 10. The experimental results were corresponded well with predicted models (COD, color, and NH{sub 3}–N removal rates of 72%, 96%, and 76%, respectively, and 0.60 (kg O{sub 3}/kg COD OC). The results obtained in the stabilized leachate treatment were compared with those from other treatment processes, such as ozone only and persulfate S{sub 2}O{sub 8}{sup 2-} only, to evaluate its effectiveness. The combined method (i.e., O{sub 3}/S{sub 2}O{sub 8}{sup 2-}) achieved higher removal efficiencies for COD, color, and NH{sub 3}–N compared with other studied applications. Furthermore, the new method is more efficient than ozone/Fenton in advanced oxidation process in the treatment of the same studied leachate.

Abu Amr, Salem S. [School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Aziz, Hamidi Abdul, E-mail: cehamidi@eng.usm.my [School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Adlan, Mohd Nordin [School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

2013-06-15

34

Ultrasonic-assisted chemical oxidative cutting of multiwalled carbon nanotubes with ammonium persulfate in neutral media  

NASA Astrophysics Data System (ADS)

A new, facile, and mild approach was developed to cut the conventional long and entangled multiwalled carbon nanotubes (MWCNTs) to short and dispersed ones with length of less than 1 ?m by ultrasonic-assisted chemical oxidation with ammonium persulfate (APS) in neutral aqueous solution at room temperature. The resulting products were characterized with Fourier transform infrared (FTIR), Raman, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and transmission electron microscope (TEM) techniques. The shortened MWCNTs formed stable dispersion state in water without the help of surfactants that provided possibility for further functionalizations and applications.

Liu, Peng; Wang, Tingmei

2009-12-01

35

Ferrous-activated persulfate oxidation of arsenic(III) and diuron in aquatic system.  

PubMed

In situ chemical oxidation (ISCO) can be an effective technology for the remediation of soil and groundwater polluted by organic and inorganic contaminants. This study investigated the oxidation of arsenic(III) (As(III)) and diuron using ferrous activated persulfate-based ISCO. The results indicated that Fe(II)/persulfate oxidation could be an effective method to oxidize As(III) and diuron. Effects of pH, S2O8(2-) and Fe(II) amounts on the destruction of As(III) and diuron were examined in batch experiments. Acidic conditions favored the removal of As(III) and diuron. Four chelating agents, citric acid (CA), Na2S2O3, diethylene triamine pentaacetic acid (DTPA) and ethylene diamine tetraacetic acid disodium (EDTA-Na2) were used in attempt to maintain the quantity of ferrous ion in solution. In our experiments, CA and Na2S2O3 were found to be more effective than DTPA and EDTA-Na2. Our results also revealed a widely practical prospect of inorganic chelating agent Na2S2O3. Hydroxyl and sulfate radical were determined to play key roles in the oxidation process by using ethanol and tertiary butanol as molecular probes. Oxidation of As(III) yielded As(V) via the electron-transfer reaction. In the oxidation process of diuron, a stepwise nucleophilic substitution of chlorine by hydroxyl and a stepwise oxidation process of the methyl on the dimethylurea group by hydroxyl and sulfate radical were proposed. PMID:24220194

Zhou, Lei; Zheng, Wei; Ji, Yuefei; Zhang, Jinfeng; Zeng, Chao; Zhang, Ya; Wang, Qi; Yang, Xi

2013-12-15

36

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

EPA Science Inventory

Activated persulfate (Na2S2O8) regeneration of methyl tert-butyl ether (MTBE) and chloroform-spent GAC was evaluated in this study. Thermal-activation of persulfate was effective and resulted in greater MTBE removal than either alkaline-activation or H2O2?persulfate binary mixtur...

37

Thermally Activated Persulfate Oxidation of Trichloroethylene (TCE) and 1,1,1Trichloroethane (TCA) in Aqueous Systems and Soil Slurries  

Microsoft Academic Search

Under thermally activated conditions (i.e., temperature of 40?99°C), there is considerable evidence that the persulfate anion () can be converted to a powerful oxidant known as the sulfate free radical (), which could be used in situ to destroy groundwater contaminants. In this laboratory study only limited trichloroethylene (TCE) degradation and no 1,1,1-trichloroethane (TCA) degradation was observed at 20°C. However,

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

2003-01-01

38

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

Microsoft Academic Search

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

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

2002-01-01

39

Novel insights into enhanced dewaterability of waste activated sludge by Fe(II)-activated persulfate oxidation.  

PubMed

The potential of Fe(II)-activated persulfate (S(2)O(8)(2-)) oxidation on enhancing the dewaterability of sludge flocs from 3-full scale wastewater treatment plants (WWTPs) were investigated. Normalized capillary suction time (CST) was applied to evaluate sludge dewaterability. Both extracellular polymeric substances (EPS) and metabolic activity of microorganisms were determined to explore the responsible mechanism. Fe(II)-S(2)O(8)(2-) oxidation effectively improved sludge dewaterability. The most important mechanisms were proposed to be the degradation of EPS incorporated in sludge flocs and rupture of microbial cells. Three-dimensional excitation-emission matrix (EEM) fluorescence spectroscopy confirmed that the powerful SO(4)(-) from Fe(II)-S(2)O(8)(2-) system destroyed the particular functional groups of fluorescing substances (i.e., aromatic protein-, tryptophan protein-, humic- and fulvic-like substances) in EPS and caused cleavage of linkages in the polymeric backbone and simultaneous destruction of microbial cells, resulting in the release of EPS-bound water, intracellular materials and water of hydration inside cells, and subsequent enhancement of dewaterability. PMID:22728175

Zhen, Guangyin; Lu, Xueqin; Li, Yuyou; Zhao, Youcai; Wang, Baoying; Song, Yu; Chai, Xiaoli; Niu, Dongjie; Cao, Xianyan

2012-09-01

40

Persulfate activation by subsurface minerals  

NASA Astrophysics Data System (ADS)

Persulfate dynamics in the presence of subsurface minerals was investigated as a basis for understanding persulfate activation for in situ chemical oxidation (ISCO). The mineral-mediated decomposition of persulfate and generation of oxidants and reductants was investigated with four iron and manganese oxides and two clay minerals at both low pH (< 7) and high pH (> 12). The manganese oxide birnessite was the most effective initiator of persulfate for degrading the oxidant probe nitrobenzene, indicating that oxidants are generated at both low and high pH regimes. The iron oxide goethite was the most effective mineral for degrading the reductant probe hexachloroethane. A natural soil and two soil fractions were used to confirm persulfate activation by synthetic minerals. The soil and soil fractions did not effectively promote the generation of oxidants or reductants. However, soil organic matter was found to promote reductant generation at high pH. The results of this research demonstrate that synthetic iron and manganese oxides can activate persulfate to generate reductants and oxidants; however, iron and manganese oxides in the natural soil studied do not show the same reactivity, most likely due to the lower masses of the metal oxides in the soil relative to the masses studied in isolated mineral systems.

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

2010-06-01

41

Degradation efficiencies of azo dye Acid Orange 7 by the interaction of heat, UV and anions with common oxidants: persulfate, peroxymonosulfate and hydrogen peroxide.  

PubMed

In this paper, the degradation of azo dye Acid Orange 7 (AO7) by three common peroxides (persulfate (PS), peroxymonosulfate (PMS) or hydrogen peroxide (H(2)O(2))) under various activation conditions, i.e., heat (25-80 degrees C), UV light (254 nm), or anions (SO(4)(2-), NO(3)(-), CO(3)(2-), HCO(3)(-), HPO(4)(2-), and Cl(-)), was investigated. The order of AO7 degradation efficiencies by heat activation is PS>PMS>H(2)O(2). PS oxidation activated by heat (>50 degrees C) is an effective degradation technology, while PMS and H(2)O(2) are hardly activated. When assisted by UV, peroxides could all be activated and degrade AO7 quickly. The order is PS>H(2)O(2)>PMS. We activated peroxides, for the first time, by using some anions and compared the subsequently degradation efficiencies of AO7. It was found that PMS could be activated by some anions, but PS and H(2)O(2) cannot. The activation efficiencies of PMS by SO(4)(2-) and NO(3)(-) are negligible, whereas remarkable by HCO(3)(-), HPO(4)(2-), Cl(-) and CO(3)(2-). For HCO(3)(-), HPO(4)(2-) and Cl(-), the activation efficiencies become higher with the increase of anion concentration. For CO(3)(2-), however, the activation efficiency is higher at lower concentration. PMID:20371151

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

2010-07-15

42

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

Microsoft Academic Search

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

SAM PINO; SHIH-LIEH FANG; E. BRAVERMAN

43

Enhanced degradation of ortho-nitrochlorobenzene by the combined system of zero-valent iron reduction and persulfate oxidation in soils.  

PubMed

ortho-Nitrochlorobenzene (o-NCB) in soil poses significant health risks to human because of its persistence and high toxicity. The removal of o-NCB by both zero-valent iron (ZVI) and chemical oxidation (persulfate) was investigated by batch experiments. The o-NCB removal rate increases significantly from 15.1 to 97.3 % with an increase of iron dosage from 0.1 to 1.0 mmol g(-1). The o-NCB removal rate increases with the decrease of the initial solution pH, and a removal efficiency of 90.3 % is obtained at an initial pH value of 6.8 in this combined system. It is found that temperature and soil moisture could also increase the o-NCB removal rate. The o-NCB degradation rate increases from 83.9 to 96.2 % and from 41.5 to 82.4 % with an increase of temperature (15 to 35 °C) and soil moisture (0.25 to 1.50 mL g(-1)), respectively. Compared to the persulfate oxidation system and ZVI system, the persulfate-iron system shows high o-NCB removal capacity. o-NCB removal rates of 41.5 and 62.4 % are obtained in both the persulfate oxidation system and the ZVI system, while the removal rate of o-NCB is 90.3 % in the persulfate-iron system. PMID:24385185

Xu, Hai-bo; Zhao, Dao-yuan; Li, Yu-jiao; Liu, Pei-ya; Dong, Chang-xun

2014-04-01

44

Catalytic effects of copper(II) oxide and zinc(II) oxide on the thermal transitions of sodium and potassium persulfates  

Microsoft Academic Search

The thermal transitions of Na2S2O8 and K2S2O8 have been studied by means of a derivatograph in the presence of CuO or ZnO at various molar mixtures. A slight shift in the DTG peak of the first decomposition stage (persulfate into pyrosulfate) to higher temperature was noticed as the amount of oxide increases.

M. M. Barbooti; F. Jasim

1978-01-01

45

Remediation of phenanthrene-contaminated soil by simultaneous persulfate chemical oxidation and biodegradation processes.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous compounds with carcinogenic and/or mutagenic potential. To address the limitations of individual remediation techniques and to achieve better PAH removal efficiencies, the combination of chemical and biological treatments can be used. The degradation of phenanthrene (chosen as a model of PAH) by persulfate in freshly contaminated soil microcosms was studied to assess its impact on the biodegradation process and on soil properties. Soil microcosms contaminated with 140 mg/kgDRY SOIL of phenanthrene were treated with different persulfate (PS) concentrations 0.86-41.7 g/kgDRY SOIL and incubated for 28 days. Analyses of phenanthrene and persulfate concentrations and soil pH were performed. Cultivable heterotrophic bacterial count was carried out after 28 days of treatment. Genetic diversity analysis of the soil microcosm bacterial community was performed by PCR amplification of bacterial 16S rDNA fragments followed by denaturing gradient gel electrophoresis (DGGE). The addition of PS in low concentrations could be an interesting biostimulatory strategy that managed to shorten the lag phase of the phenanthrene biological elimination, without negative effects on the physicochemical and biological soil properties, improving the remediation treatment. PMID:24595755

Mora, Verónica C; Madueño, Laura; Peluffo, Marina; Rosso, Janina A; Del Panno, María T; Morelli, Irma S

2014-06-01

46

Ultraviolet-activated persulfate oxidation of methyl orange: a comparison between artificial neural networks and factorial design for process modelling.  

PubMed

In this work, the degradation of the azo dye methyl orange in model aqueous solutions by UVC light-induced persulfate oxidation was studied. Five operating parameters that may influence the decolorization kinetics were evaluated, namely, methyl orange (MO) (5-50 mg L(-1)) and sodium persulfate (SPS) (50-150 mg L(-1)) concentration, reaction time (up to 60 min), (un-buffered) solution pH (3-9) and the addition of NaCl (0-500 mg L(-1)). The process was simulated, applying and comparing two methodologies, namely two-level factorial design and an artificial neural network (ANN). It was found that MO concentration is the most influential parameter, followed by the reaction time and SPS concentration, while the effects of solution pH and the addition of sodium chloride are statistically less significant; this order of significance was predicted by both methodologies. The ANN can simulate the process more accurately (i.e. in terms of R(2), mean square error (MSE) and residuals) than factorial design, although it needs significantly larger sets of data and longer computational time. PMID:25338014

Frontistis, Zacharias; Hapeshi, Evroula; Fatta-Kassinos, Despo; Mantzavinos, Dionissios

2014-10-22

47

Oxidation of Orange G by persulfate activated by Fe(II), Fe(III) and zero valent iron (ZVI).  

PubMed

Persulfate (PS) was employed in the oxidation of Orange G (OG), an azo dye commonly found in textile wastewaters. Activation of PS was conducted with iron to generate sulfate free radicals (SO4(-)) with high redox potential capable to oxidize most of the organics in water. Identification of oxidation intermediates was carried out by analyzing at different times organic by-products generated from treatment of a concentrate dye solution (11.6 mM) with 153 mM of PS and 20 mM of Fe(II) at 20 °C. Intermediate reaction products (mainly phenol (PH) and benzoquinone (BQ), and in less extent aniline, phenolic compounds and naphthalene type compounds with quinone groups) were identified by GC/MS and HPLC, and an oxidation pathway was proposed for the oxidation of OG with iron activated PS. The effect of iron valence (0, II and III) in the oxidation of an aqueous solution of OG (containing 0.1 mM) was studied in a 0.5 L batch reactor at 20 °C. Initial activator and PS concentrations employed were both 1 mM. Complete pollutant removal was achieved within the first 30 min when iron II or III were employed as activators. Quinone intermediates generated during pollutant oxidation may act as electron shuttles, allowing the reduction of Fe(III) into Fe(II) in the redox cycling of iron. Therefore, activation of PS by Fe(III) allowed complete OG removal. When zero valent iron (ZVI) was employed (particle diameter size 0.74 mm) the limiting step in SO4(-) generation was the surface reaction between ZVI and the oxidant yielding a lower oxidation rate of the dye. An increase in the oxidant dosage (0.2 mM OG, 2 mM Fe(III) and 6 mM PS) allowed complete pollutant and ecotoxicity removal, as well as mineralization close to 75%. PMID:24439838

Rodriguez, S; Vasquez, L; Costa, D; Romero, A; Santos, A

2014-04-01

48

Synergetic pretreatment of waste activated sludge by Fe(II)-activated persulfate oxidation under mild temperature for enhanced dewaterability.  

PubMed

The potential benefits of Fe(II)-activated persulfate (S(2)O(8)(2-)) oxidation under mild temperature in enhancing the dewaterability of waste activated sludge were investigated. Capillary suction time (CST) was used to characterize sludge dewatering. Zeta potential, particle size distribution, three-dimensional excitation-emission matrix (EEM) fluorescence spectroscopy, fourier-transformed infrared (FT-IR) spectroscopy and scanning electronic microscopy (SEM) were employed to explore influencing mechanisms. The results indicated that the dewaterability was deteriorated with single thermal treatment, but significantly enhanced in the presence of Fe(II)-S(2)O(8)(2-) oxidation and further advanced together with thermal treatment. EEM and FT-IR analysis indicated that combined thermal and Fe(II)-S(2)O(8)(2-) oxidation pretreatment led to degrading of tyrosine and tryptophan protein-like substances in extracellular polymeric substances (EPS) and cleavage of linkages in polymeric backbone. SEM images further revealed the rupture of sludge flocs at the colloidal scale, which contributed to the release of EPS-bound water and interstitial water trapped between flocs, and subsequent enhanced dewaterability. PMID:22989633

Zhen, Guangyin; Lu, Xueqin; Wang, Baoying; Zhao, Youcai; Chai, Xiaoli; Niu, Dongjie; Zhao, Aihua; Li, Yuyou; Song, Yu; Cao, Xianyan

2012-11-01

49

Innovative combination of electrolysis and Fe(II)-activated persulfate oxidation for improving the dewaterability of waste activated sludge.  

PubMed

The feasibility of electrolysis integrated with Fe(II)-activated persulfate (S2O8(2-)) oxidation to improve waste activated sludge (WAS) dewaterability was evaluated. The physicochemical properties (sludge volume (SV), total suspended solids (TSS) and volatile suspended solids (VSS)) and extracellular polymeric substances (EPS), including slime EPS, loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS) were characterized to identify their exact roles in sludge dewatering. While dewaterability negatively corresponded to LB-EPS, TB-EPS, protein (PN) and polysaccharide (PS) in LB-EPS and TB-EPS, it was independent of SV, TSS, VSS, slime EPS and PN/PS. Further study through scanning electron microscope (SEM) verified the entrapment of bacterial cells by TB-EPS, protecting them against electrolysis disruption. Comparatively, electrolysis integrated with S2O8(2-)/Fe(II) oxidation was able to effectively disrupt the protective barrier and crack the entrapped cells, releasing the water inside EPS and cells. Therefore, the destruction of both TB-EPS and cells is the fundamental reason for the enhanced dewaterability. PMID:23570713

Zhen, Guang-Yin; Lu, Xue-Qin; Li, Yu-You; Zhao, You-Cai

2013-05-01

50

In situ iron activated persulfate oxidative fluid sparging treatment of TCE contamination — A proof of concept study  

NASA Astrophysics Data System (ADS)

In situ chemical oxidation (ISCO) is considered a reliable technology to treat groundwater contaminated with high concentrations of organic contaminants. An ISCO oxidant, persulfate anion (S 2O 82-) can be activated by ferrous ion (Fe 2+) to generate sulfate radicals ( Eo = 2.6 V), which are capable of destroying trichloroethylene (TCE). The property of polarity inhibits S 2O 82- or sulfate radical (SO 4rad - ) from effectively oxidizing separate phase TCE, a dense non-aqueous phase liquid (DNAPL). Thus the oxidation primarily takes place in the aqueous phase where TCE is dissolved. A bench column study was conducted to demonstrate a conceptual remediation method by flushing either S 2O 82- or Fe 2+ through a soil column, where the TCE DNAPL was present, and passing the dissolved mixture through either a Fe 2+ or S 2O 82- fluid sparging curtain. Also, the effect of a solubility enhancing chemical, hydroxypropyl-?-cyclodextrin (HPCD), was tested to evaluate its ability to increase the aqueous TCE concentration. Both flushing arrangements may result in similar TCE degradation efficiencies of 35% to 42% estimated by the ratio of TCE degraded/(TCE degraded + TCE remained in effluent) and degradation byproduct chloride generation rates of 4.9 to 7.6 mg Cl - per soil column pore volume. The addition of HPCD did greatly increase the aqueous TCE concentration. However, the TCE degradation efficiency decreased because the TCE degradation was a lower percentage of the relatively greater amount of dissolved TCE by HPCD. This conceptual treatment may serve as a reference for potential on-site application.

Liang, Chenju; Lee, I.-Ling

2008-09-01

51

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

EPA Science Inventory

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

52

Persulfate Digestion and Simultaneous Colorimetric Analysis of Carbon and Nitrogen in Soil Extracts  

Microsoft Academic Search

Doyle and Schimel, 1998). Persulfate oxidation has been developed for soil extract DON (Cabrera and Persulfate digestions have been used for analyzing dissolved or- Beare, 1993) and for fresh water DOC (McDowell et ganic carbon (DOC) and nitrogen (DON), but most existing methods do not simultaneously analyze the same digest. Persulfate oxidizes al., 1987). It is conveniently run in an

Allen Doyle; Michael N. Weintraub; Joshua P. Schimel

2004-01-01

53

Effect of metal oxides on the reactivity of persulfate/Fe(II) in the remediation of diesel-contaminated soil and sand.  

PubMed

The effect of metal oxides on the ability of persulfate (PS) with Fe(II) to remediate diesel-contaminated soil was investigated. In both natural soil and purchased sand, the highest diesel degradation occurred at pH 3 and the optimum molar ratio of PS/Fe(II) was 100:1 (i.e. 500 mM PS to 5 mM Fe(II)). Moreover, adding Fe(II) increased PS reactivity more in soil than it did in sand, indicating the involvement of metal oxides in the soil matrix. Evaluating the effects of metal oxides (i.e. goethite, hematite, magnetite, and manganese oxide) on the reactivity of PS with/without Fe(II) in a system containing diesel-contaminated sand revealed that manganese oxide increased PS activity the most and that the highest diesel degradation by PS occurred when both manganese oxide and Fe(II) were used as activators. XRD did not show the transformation of manganese oxide in the presence of Fe(II). SEM-EDS showed the association of Fe(II) on the surface of manganese oxide, and ICP analysis revealed that almost all the added Fe(II) adsorbed to manganese oxide but almost none adsorbed to iron oxides under acidic conditions. Therefore, the high reactivity of PS could be due to the high density of Fe(II) over the surface of manganese oxide. PMID:20633989

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

2010-10-15

54

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

55

Persulfate injection into a gasoline source zone  

NASA Astrophysics Data System (ADS)

One pore volume of unactivated sodium persulfate was delivered into an emplaced gasoline residual source zone at CFB Borden. Concentrations of inorganic species (S2O82 -, SO42 -, Na+, dissolved inorganic carbon (DIC)) and selected gasoline compounds (benzene, toluene, ethylbenzene, xylenes, trimethylbenzenes and naphthalene) were monitored across a transect equipped with 90 multilevel sampling points for > 10 months post-injection. Mass loading (M?) of compounds constructed from the transect data was used for assessment purposes. Breakthrough of inorganic species was observed when the injection slug crossed the monitoring transect. An increase in M indicated persulfate consumption during oxidation of gasoline compounds or degradation due to the interaction with aquifer materials. M increased by > 100% suggesting some mineralization of gasoline compounds during treatment. Mass loading for all the monitored gasoline compounds reduced by 46 to 86% as the inorganic slug crossed the monitoring transect. The cumulative mass discharge across the monitoring transect was 19 to 58% lower than that expected without persulfate injection. After the inorganic injection slug was flushed from the source zone a partial rebound (40 to 80% of baseline levels) of mass discharge of the monitored gasoline compounds was observed. The ensemble of data collected provides insight into the fate and transport of the injected persulfate solution, and the accompanying treatment of a gasoline the source zone.

Sra, Kanwartej S.; Thomson, Neil R.; Barker, Jim F.

2013-07-01

56

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

57

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

EPA Science Inventory

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

58

pH dependence of persulfate activation by EDTA/Fe(III) for degradation of trichloroethylene  

NASA Astrophysics Data System (ADS)

The ability of free ferrous ion activated persulfate (S 2O 82-) to generate sulfate radicals (SO 4- rad ) for the oxidation of trichloroethylene (TCE) is limited by the scavenging of SO 4- rad with excess Fe 2+ and a quick conversion of Fe 2+ to Fe 3+. This study investigated the applicability of ethylene-diamine-tetra-acetic acid (EDTA) chelated Fe 3+ in activating persulfate for the destruction of TCE in aqueous phase under pH 3, 7 and 10. Fe 3+ and EDTA alone did not appreciably degrade persulfate. The presence of TCE in the EDTA/Fe 3+ activated persulfate system can induce faster persulfate and EDTA degradation due to iron recycling to activate persulfate under a higher pH condition. Increasing the pH leads to increases in pseudo-first-order-rate constants for TCE, S 2O 82- and EDTA degradations, and Cl generation. Accordingly, the experiments at pH 10 with different EDTA/Fe 3+ molar ratios indicated that a 1/1 ratio resulted in a remarkably higher degradation rate at the early stage of reaction as compared to results by other ratios. Higher persulfate dosage under the EDTA/Fe 3+ molar ratio of 1/1 resulted in greater TCE degradation rates. However, increases in persulfate concentration may also lead to an increase in the rate of persulfate consumption.

Liang, Chenju; Liang, Ching-Ping; Chen, Chi-Chin

2009-05-01

59

Sonochemical acceleration of persulfate decomposition  

Microsoft Academic Search

The decomposition kinetics of potassium persulfate in aqueous solution have been investigated using a radical trapping method. The use of ultrasound was found to markedly accelerate the decomposition so that the sonochemical process at 25°C occurs at the same rate as the purely thermal reaction at 55°C. The effect of ultrasound intensity has also been studied and can be used

Gareth J. Price; Andrew A. Clifton

1996-01-01

60

Potential for activated persulfate degradation of BTEX contamination  

Microsoft Academic Search

The present study focused on evaluation of activated persulfate (PS) anion (S2O82?) oxidative degradation of benzene, toluene, ethylbenzene, and xylene (constituents of gasoline and known collectively as BTEX) contamination. The results indicated that BTEX were effectively oxidized by PS in aqueous and soil slurry systems at 20°C. PS can be activated thermally, or chemically activated with Fe2+ to form the

Chenju Liang; Chiu-Fen Huang; Yan-Jyun Chen

2008-01-01

61

Agent neutralization studies III. Detoxification of VX in aqueous persulfate. Final report, May-August 1993  

SciTech Connect

Aqueous solutions of persulfate salts are frequently used to mineralize organic substrates in the course of total organic carbon analyses. A study has been conducted at the U.S. Army Edgewood Research, Development and Engineering Center to determine whether this approach may be useful to neutralize the nerve agent VX. VX was reacted with aqueous ammonium persulfate at 90 deg C and 70 deg C. The concentration of agent and the acidity of the mixture were varied. 31P-NMR was used to monitor the destruction of VX as well as the formation and degradation of the phosphorus-containing products. A titration procedure using ferrous sulfate and ceric ammonium nitrate was used to monitor the consumption of persulfate. The products formed and their stabilities were found to vary significantly with the acidity of the solution. Nuclear magnetic resonance, Oxidation, VX, Ammonium persulfate, Mineralization, Temperature effects, Chemical agent disposal.

Hovanec, J.W.; Albizo, J.M.; Henderson, V.D.; Szafraniec, L.L.; Beaudry, W.T.

1994-06-01

62

Solid State Cleavage of Semicarbazones and Phenylhydrazones with Ammonium Persulfate-Clay using Microwave or Ultrasonic Irradiation  

Microsoft Academic Search

Adsorbed on clay, semicarbazone and phenylhydrazone derivatives are oxidatively cleaved in solid state to generate the corresponding ketones by ammonium persulfate using microwave or ultrasonic irradiation. © 1997 Elsevier Science Ltd.

Rajender S Varma; Harshadas M Meshram

1997-01-01

63

Targeted proteomic analyses of nasal lavage fluid in persulfate-challenged hairdressers with bleaching powder-associated rhinitis.  

PubMed

Hairdressers have an increased risk for developing airway symptoms, for example, asthma and rhinitis. Persulfates, which are oxidizing agents in bleaching powder, are considered important causal agents for these symptoms. However, the underlying mechanisms are unclear. The aim was therefore to measure proteomic changes in nasal lavage fluid from persulfate-challenged subjects to identify proteins potentially involved in the pathogenesis of bleaching powder-associated rhinitis or candidate effect biomarkers for persulfate. Also, oxidized peptides were measured to evaluate their usefulness as biomarkers for persulfate exposure or effect, for example, oxidative stress. Samples from hairdressers with and without bleaching powder-associated rhinitis were analyzed with liquid chromatography tandem mass spectrometry using selected reaction monitoring to target 246 proteins and five oxidized peptides. Pathway analysis was applied to obtain a functional overview of the proteins. Several proteins involved in biologically meaningful pathways, functions, or disorders, for example, inflammatory responses, oxidative stress, epithelium integrity, and dermatological disorders, changed after the persulfate challenge. A list with nine proteins that appeared to be affected by the persulfate challenge and should be followed up was defined. An albumin peptide containing oxidized tryptophan increased 2 h and 5 h after the challenge but not after 20 min, which indicates that such peptides may be useful as oxidative stress biomarkers. PMID:25546367

Mörtstedt, Harriet; Ali, Neserin; Kåredal, Monica; Jacobsson, Helene; Rietz, Emelie; Kronholm Diab, Kerstin; Nielsen, Jörn; Jönsson, Bo A G; Lindh, Christian H

2015-02-01

64

Degradation of dimethyl phthalate in solutions and soil slurries by persulfate at ambient temperature.  

PubMed

The degradation of dimethyl phthalate (DMP) by persulfate at ambient temperature (T=20-40°C) was investigated in aqueous solutions and soil slurries to assess the feasibility of using persulfate to remediate DMP contaminated soil and groundwater. First, the effects of temperature, initial oxidant concentration, initial DMP concentration and initial solution pH on the removal of DMP and TOC were studied in aqueous solutions. The results show that persulfate at 40°C can effectively mineralize DMP. Furthermore, dimethyl 4-hydroxyl phthalate, maleic acid and oxalic acid were identified as the degradation intermediates, and degradation pathways were proposed. Lastly, persulfate at 40°C was applied to remediate soil spiked with DMP at ? 600 mg/kg. The results show that persulfate at 40°C is highly effective for the remediation of DMP contaminated soil. Overall, this study provides fundamental and practical knowledge for the treatment of emerging phthalate esters (PAEs) contaminated soil and groundwater, as well as PAEs contaminated industrial wastewater, with persulfate at ambient temperature. PMID:24637446

Wang, Zhen; Deng, Dayi; Yang, Liling

2014-04-30

65

Electrolytic Manipulation of Persulfate Reactivity by Iron Electrodes for TCE Degradation in Groundwater  

PubMed Central

Activated persulfate oxidation is an effective in situ chemical oxidation process for groundwater remediation. However, reactivity of persulfate is difficult to manipulate or control in the subsurface causing activation before reaching the contaminated zone and leading to a loss of chemicals. Furthermore, mobilization of heavy metals by the process is a potential risk. An effective approach using iron electrodes is thus developed to manipulate the reactivity of persulfate in situ for trichloroethylene (TCE) degradation in groundwater, and to limit heavy metals mobilization. TCE degradation is quantitatively accelerated or inhibited by adjusting the current applied to the iron electrode, following k1 = 0.00053•Iv + 0.059 (?122 A/m3 ? Iv ? 244 A/m3) where k1 and Iv are the pseudo first-order rate constant (min?1) and volume normalized current (A/m3), respectively. Persulfate is mainly decomposed by Fe2+ produced from the electrochemical and chemical corrosion of iron followed by the regeneration via Fe3+ reduction on the cathode. SO4•? and •OH co-contribute to TCE degradation, but •OH contribution is more significant. Groundwater pH and oxidation-reduction potential can be restored to natural levels by the continuation of electrolysis after the disappearance of contaminants and persulfate, thus decreasing adverse impacts such as the mobility of heavy metals in the subsurface. PMID:24328192

Yuan, Songhu; Liao, Peng; Alshawabkeh, Akram N.

2014-01-01

66

Electrolysis cell for the manufacture of persulfates  

NASA Technical Reports Server (NTRS)

A cell for the electrolytic generation of persulfates, characterized by the fact that a housing acts as cathode, is made of metal, and consists of a lower electrolytically active section and an upper electrolytically inactive section. It is designed so that there is produced the greatest possible current density suited to produce the desired electrolysis effect. This invention, compared to the devices used until now, exhibits considerable advantages whereby it is particularly suited for the production of potassium persulfate.

Cueto, J. M.

1986-01-01

67

Modification of indium tin oxide with persulfate-based photochemistry toward facile, rapid, and low-temperature interface-mediated multicomponent assembling.  

PubMed

The well-controlled material assembly and patterning on indium tin oxide (ITO) coating layer is of great importance for the practical fabrication of a functional device. Nonetheless, the conventional way to achieve this aim is still mainly based on the combination of photolithography with pattern transfer techniques (e.g., wet/dry etching, ?CP) due to the lack of one method that is able to directly afford site-selective ITO surface tailoring and subsequent templating for material assembly. Herein, we reported a novel, fast, and efficient photochemical reaction to accurately tailor the surface property of ITO with light-controlled site-selectivity, thus resulting in direct photoresist-free and etching/contact-free lithographic patterning of building blocks, e.g., ZnO, BaTiO3, CdS, lipid membrane, conductive polymers, colloids, and liquid crystals. The entire process reveals new interfacial chemistry suitable for inorganic metal oxide and its important versatile implications for low-cost fabrication of large-area flat and flexible optical/electronic/biorelated devices. PMID:24716839

Mu, Xiaoyan; Guo, Shulei; Zhang, Linyuan; Yang, Peng

2014-05-01

68

Heat activated vent  

SciTech Connect

The heat activated vent for releasing an excess internal pressure in a container which pressure accompanied by an abnormal rise in an internal temperature of the container uses a spring to store sufficient energy to propel a barb or spike to pierce a thin diaphragm. A pierceable thin diaphragm is positioned adjacent to the sharp end of the barb and is arranged to provide a fluid tight seal across an open end of a hollow vent housing. The spring is in the form of a leaf spring having a diaphragm piercing upright barb at one end thereof while the other end of the leaf spring is supported in a fixed position within the housing. The end of the spring carrying the barb is normally retained in a position wherein the barb is spaced from the diaphragm by a preshaped end of a cantilevered beam of a material having a memory capability. A temperature rise of the container is communicated to the vent housing which, in turn, is effective to produce a temperature rise of the memory material to allow the memory material to return to its original shape. The original shape of the memory material is effective to release the barb carrying end of the leaf spring to allow the spring to propel the diaphragm piercing barb into the diaphragm to produce a hole in the diaphragm for releasing the internal pressure in the container into a fluid escape channel from the vent housing.

Kelley, J.A.; Michener, C.A.

1984-02-07

69

Degradation of ciprofloxacin and sulfamethoxazole by ferrous-activated persulfate: implications for remediation of groundwater contaminated by antibiotics.  

PubMed

The wide occurrence of antibiotics in groundwater raised great scientific interest as well as public awareness in recent years due to their potential ability to spread antibiotic resistant gene and pose risk to humans. The present study investigated the ferrous ion (Fe(II)) activated decomposition of persulfate (S2O8(2-)), as a potential in situ chemical oxidation (ISCO) approach, for remediation of groundwater contaminated by antibiotics. Fe(II)-persulfate mediated ciprofloxacin (CIP) degradation was found to be more efficient than sulfamethoxazole (SMX) at near neutral pH (pH6.0), probably due to the higher electric density in CIP molecule and its ability to form complex with Fe(II) as a ligand. Hydroxyl (HO) and sulfate radical (SO4(-)) were determined to be responsible for the degradation of CIP and SMX in Fe(II)-persulfate system by molecular probes. No enhancement in the degradation of CIP was observed when citrate (CA), ethylenediaminetetraacetate (EDTA) and (S,S)-ethylenediamine-N,N'-disuccinate (EDDS) were used as Fe(II) chelating agents in Fe(II)-persulfate system. For SMX, CA and EDTA accelerated the degradation by Fe(II)-persulfate. Degradation of antibiotics in river water matrix was nearly the same as that in Milli-Q water, implying the possibility of using Fe(II)-persulfate for antibiotics depletion under environmentally relevant condition. A comparison of the degradation efficiency of SMX with other sulfonamides and sulfanilic acid indicated that the heterocyclic ring has a large impact on the degradation of sulfonamides. Transformation products of CIP and SMX by Fe(II)-persulfate were analyzed by solid phase extraction-liquid chromatography-mass spectrometry (SPE-LC-MS) technique. Based on the intermediate products, Fe(II)-persulfate mediated CIP degradation pathways were tentatively proposed. PMID:24342085

Ji, Yuefei; Ferronato, Corinne; Salvador, Arnaud; Yang, Xi; Chovelon, Jean-Marc

2014-02-15

70

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

E-print Network

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 21 soil) and low (9.3 g kg 21 soil) additions of sodium persulfate to a petroleum hydrocarbon-contaminated soil, as well as sand spiked with diesel. Recoveries of 9561 % and 96610 % were observed with the higher application rate in the contaminated soil and spiked sand, respectively. Corresponding recoveries of 8665 % and 117619 % 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.

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

2013-01-01

71

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

72

Degradation of carbamazepine by Fe(II)-activated persulfate process.  

PubMed

Experimental studies were conducted to investigate the oxidative degradation of carbamazepine (CBZ), one of the most frequently detected pharmaceuticals in various waters, by Fe(II)-activated persulfate process. Results show that the Fe(2+)/S2O8(2-) process is very effective for the elimination of CBZ and characterized by a two-stage kinetics (a rapid initial decay followed by a retardation stage). CBZ degradation reaction was observed to be pH dependent and the optimum pH is 3.0 in the range of 2.00-7.87. The concentration of Fe(2+) and S2O8(2-) exhibited a noticeable influence on CBZ removal efficiency, where [S2O8(2-)] exerted more significant effects than that of [Fe(2+)]. The optimal molar ratio of CBZ, Fe(2+), and S2O8(2-) is found to be 1:5:40. The effect of various inorganic anions on CBZ removal was also evaluated under the optimal conditions. The anions NO3(-), SO4(2-) and H2PO4(-)caused a negative effect on the performance of this process, while Cl(-) interestingly accelerated CBZ degradation. The higher the Cl(-) concentration, the faster the CBZ decay rate. The intermediates were identified during CBZ degradation with and without the presence of Cl(-). The evolution of intermediates for these two scenarios was compared. The decay pathways of CBZ were proposed accordingly. PMID:24462988

Rao, Y F; Qu, Liang; Yang, Haisong; Chu, W

2014-03-15

73

75 FR 2112 - Persulfates From the People's Republic of China: Notice of Rescission of the 2008-2009...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Trade Administration [A-570-847] Persulfates From the People's Republic of China...review of the antidumping duty order on persulfates from the People's Republic of China...FMC''), a domestic producer of persulfates, requested that the Department...

2010-01-14

74

Polymer\\/silicate nanocomposites synthesized with potassium persulfate at room temperature: polymerization mechanism, characterization, and mechanical properties of the nanocomposites  

Microsoft Academic Search

Polymer\\/silicate nanocomposites were synthesized using potassium persulfate (KPS) in the presence of silicate and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) without exterior redox co-catalysts at a room temperature. A mechanism for the room temperature polymerization in the presence of silicate was suggested: AMPS attached on the surface of silicate layers would oxidize Fe+2 in silicate lattice to become Fe+3 and the Fe+3 would

Yeong Suk Choi; Hyeong Taek Ham; In Jae Chung

2003-01-01

75

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

Federal Register 2010, 2011, 2012, 2013, 2014

...COMMISSION [Investigation No. 731-TA-749 (Third Review)] Persulfates From China; Correction to Notice of institution AGENCY...five-year review concerning the antidumping duty order on persulfates from China with an incorrect effective date....

2013-03-06

76

Cocatalyst effect in potassium persulfate initiated grafting onto chitosan  

Microsoft Academic Search

Methyl methacrylate and methyl acrylate were grafted onto chitosan by using potassium persulfate alone as redox initiator and in combination with MnCl2 and CuCl2, as inorganic, and both ammonium tartrate and oxalate as organic cocatalysts. The extent of grafting was found to depend mainly on the nature of the cocatalysts used.

J. Retuert; M. Yazdani-Pedram

1993-01-01

77

Free radical degradation of chitosan with potassium persulfate  

Microsoft Academic Search

A thermal dissociation initiator, potassium persulfate (KPS), is added to the chitosan solution at 70 °C; immediately, the solution viscosity and the molecular weight of chitosan decrease in a very short time. Size exclusion chromatography, nuclear magnetic resonance and electron spin resonance were used to study the degradation mechanism. A free radical degradation mechanism of chitosan by KPS is then proposed.

Shih-Chang Hsu; Trong-Ming Don; Wen-Yen Chiu

2002-01-01

78

Voltammetric determination of persulfate anions using an electrode modified with a Prussian blue film  

Microsoft Academic Search

Prussian blue [PB, iron(III) hexacyanoferrate(II)] films are effective for the electrocatalysis of the persulfate (peroxodisulfate)\\/sulfate redox system. This has been exploited in the voltammetric determination of persulfate anions using a PB-modified platinum disc electrode. A linear correlation between electrocatalytic current and persulfate concentration was found for the range 5×10?5 to 3×10?3 mol dm?3, using 0.100 mol dm?3 potassium chloride as

Marcelo F. de Oliveira; Roger J. Mortimer; Nelson R. Stradiotto

2000-01-01

79

Kinetics of radical-chain decomposition of persulfate in aqueous solutions of organic compounds  

SciTech Connect

The mechanism of the radical-chain decomposition of persulfate in an aqueous medium in the presence of organic compounds was analyzed in an inert atmosphere. It was found that with variation in the substrate or persulfate concentration over wide limits, there is a regular change in the partial orders of the reaction: The reaction order with respect to persulfate varies from 3/2 to 1, and that with respect to the substrate from 0 to 1.

Berlin, A.A

1986-07-01

80

Leaching of a copper flotation concentrate with ammonium persulfate in an autoclave system  

NASA Astrophysics Data System (ADS)

The leaching behavior of a copper flotation concentrate was investigated using ammonium persulfate (APS) in an autoclave system. The decomposition products of APS, active oxygen, and acidic medium were used to extract metals from the concentrate. Leaching experiments were performed to compare the availability of APS as an oxidizing agent for leaching of the concentrate under atmospheric conditions and in an autoclave system. Leaching temperature and APS concentration were found to be important parameters in both leaching systems. Atmospheric leaching studies showed that the metal extractions increased with the increase in APS concentration and temperature (up to 333 K). A similar tendency was determined in the autoclave studies up to 423 K. It was also determined that the metal extractions decreased at temperatures above 423 K due to the passivation of the particle surface by molten elemental sulfur. The results showed that higher copper extractions could be achieved using an autoclave system.

Deniz Turan, M.; Soner Altundo?an, H.

2014-09-01

81

78 FR 64244 - Persulfates From China; Revised Schedule for the Subject Investigation  

Federal Register 2010, 2011, 2012, 2013, 2014

...INTERNATIONAL TRADE COMMISSION [Investigation No. 731-TA-749 (Third Review)] Persulfates From China; Revised Schedule for the Subject Investigation AGENCY: United States International Trade Commission....

2013-10-28

82

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

Federal Register 2010, 2011, 2012, 2013, 2014

...COMMISSION [Investigation No. 731-TA-749 (Third Review)] Persulfates From China; Notice of Commission Determination To Conduct...determine whether revocation of the antidumping duty order on persulfates from China would be likely to lead to continuation or...

2013-06-12

83

Fe/S doped granular activated carbon as a highly active heterogeneous persulfate catalyst toward the degradation of Orange G and diethyl phthalate.  

PubMed

Fe/S doped granular activated carbon (Fe/SGAC) was synthesized with ferric nitrate, Na2S2O3 and (NH4)2S2O8 via an impregnation-precipitation, reduction-oxidation combining with aqueous-phase synthesis method treatment. Surface density of functional groups, surface area changes as well as the chemical state inside Fe/SGAC catalyst were studied by Boehm titration, N2 adsorption and X-ray photoelectron spectroscopy (XPS). The reactivity of the catalysts was tested by degrading Orange G (OG) and diethyl phthalate (DEP). The Fe/SGAC catalysts could significantly enhance the removal rate of OG as compared to persulfate alone and PS/GAC. And the catalytic capacity was also enhanced by S doping. But the degradation of DEP under the similar condition was inhibited by adsorption process because of the different hydrophobicities of OG and DEP molecule. Fe2O3/FeOOH (Fe(3+)) (represents ferrihydrite) together with FeO/Fe3O4 (Fe(2+)) and Fe2O3-satellite, which provide the new active site for persulfate catalyst was found to be the major components of iron element in Fe/SGAC catalyst; the existence of FeS2(S(-)) for sulfur element verified the assumption that the doped S element promoted the electron transfer between the persulfate species and iron oxide at the interface. COD removal experiment further confirmed that mostly contaminant removal was owed to the Fe/SGAC catalytic persulfate oxidation process. PMID:24461853

Pu, Mengjie; Ma, Yongwen; Wan, Jinquan; Wang, Yan; Huang, Mingzhi; Chen, Yangmei

2014-03-15

84

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

Federal Register 2010, 2011, 2012, 2013, 2014

...731-TA-749 (Third Review)] Persulfates From China; Scheduling of a Full Five-Year...Concerning the Antidumping Duty Order on Persulfates from China AGENCY: United States International...revocation of the antidumping duty order on persulfates from China would be likely to lead...

2013-08-27

85

76 FR 13358 - Persulfates From the People's Republic of China: Preliminary Results of the 2009-2010 Antidumping...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Trade Administration [A-570-847] Persulfates From the People's Republic of China...review of the antidumping duty order on persulfates from the People's Republic of China...Register the antidumping duty order on persulfates from the PRC.\\1\\ On July 1,...

2011-03-11

86

78 FR 13891 - Persulfates From China; Institution of a Five-Year Review Concerning the Antidumping Duty Order...  

Federal Register 2010, 2011, 2012, 2013, 2014

...731-TA-749 (Third Review)] Persulfates From China; Institution of a Five-Year...Concerning the Antidumping Duty Order on Persulfates From China AGENCY: United States International...revocation of the antidumping duty order on persulfates from China would be likely to lead...

2013-03-01

87

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

Federal Register 2010, 2011, 2012, 2013, 2014

...Trade Administration [A-570-847] Persulfates From the People's Republic of China...review of the antidumping duty order on persulfates from the People's Republic of China...review of the antidumping duty order on persulfates from the PRC pursuant to section...

2013-07-08

88

76 FR 28419 - Persulfates From the People's Republic of China: Final Results of the 2009-2010 Antidumping Duty...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Trade Administration [A-570-878] Persulfates From the People's Republic of China...review of the antidumping duty order on persulfates from the People's Republic of China...FMC''), a domestic producer of persulfates and an interested party in this...

2011-05-17

89

76 FR 35402 - Persulfates From the People's Republic of China: Notice of Correction to the Final Results of the...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Trade Administration [A-570-847] Persulfates From the People's Republic of China...review of the antidumping duty order on persulfates from the People's Republic of China...incorrect case number associated with persulfates from the PRC (i.e., case...

2011-06-17

90

The control of emerging haloacetamide DBP precursors with UV/persulfate treatment.  

PubMed

Haloacetamides (HAcAms), an emerging class of nitrogen-containing disinfection byproducts (N-DBPs) of health concern in drinking water, have been reported to occur in treated drinking waters at low ?g/L levels typically. The objective of this study was to examine the potential of an ultraviolet light/persulfate (UV/PS) oxidation technology to reduce the precursors of HAcAms and also minimize the formation of other N-DBPs upon subsequent chlorination. Low-pressure UV photolysis alone and PS pre-oxidation alone did not significantly affect HAcAm formation, however UV/PS pre-oxidation achieved a statistically significant reduction in HAcAm formation and also reduced bromine incorporation into the HAcAms. UV/PS also showed a good performance in removing the precursors of haloacetonitriles and halonitromethanes prior to chlorination. Therefore, UV/PS has the potential to minimize the formation of a range of N-DBPs in organic nitrogen-rich waters where N-DBP precursors are prevalent. However, these benefits should be weighed against the potential drawbacks of increased bromate and sulfate formation, particularly in high-bromide waters. PMID:25267364

Chu, Wenhai; Li, Dongmei; Gao, Naiyun; Templeton, Michael R; Tan, Chaoqun; Gao, Yuqiong

2014-09-22

91

Degradation and dechlorination of pentachlorophenol by microwave-activated persulfate.  

PubMed

The degradation performance of pentachlorophenol (PCP) by the microwave-activated persulfate (MW/PS) process was investigated in this study. The results indicated that degradation efficiency of PCP in the MW/PS process followed pseudo-first-order kinetics, and compared with conventional heating, microwave heating has a special effect of increasing the reaction rate and reducing the process time. A higher persulfate concentration and reaction temperature accelerated the PCP degradation rate. Meanwhile, increasing the pH value and ionic strength of the phosphate buffer slowed down the degradation rate. The addition of ethanol and tert-butyl alcohol as hydroxyl radical and sulfate radical scavengers proved that the sulfate radicals were the dominant active species in the MW/PS process. Gas chromatography-mass spectrometry (GC-MS) was employed to identify the intermediate products, and then a plausible degradation pathway involving dechlorination, hydrolysis, and mineralization was proposed. The acute toxicity of PCP, as tested with Photobacterium phosphoreum, Vibrio fischeri, and Vibrio qinghaiensis, was negated quickly during the MW/PS process, which was in agreement with the nearly complete mineralization of PCP. These results showed that the MW/PS process could achieve a high mineralization level in a short time, which provided an efficient way for PCP elimination from wastewater. PMID:25328098

Qi, Chengdu; Liu, Xitao; Zhao, Wei; Lin, Chunye; Ma, Jun; Shi, Wenxiao; Sun, Qu; Xiao, Hao

2014-10-21

92

Degradation of TCE using Persulfate (PS) and Peroxymonosulfate (PMS): Effect of Inorganic Ions in Groundwater  

E-print Network

Abstract — The objective of this study was to investigate the effects of inorganic ions on persulfate (PS) and peroxymonosulfate (PMS) oxidation to degrade trichloroethylene (TCE) in groundwater. First, the groundwater samples, which was taken from Wonju, Korea, were analyzed, and the highest concentration of target ions (Mg 2+, Ca 2+, Fe 2+, Mn 2+, Cl-, HCO 3) in those samples were used for the batch experiment. Based on batch test, all of target ions did not neither increase nor decrease the reactivity of both PS and PMS. Because of the fluctuation of groundwater compositions, it could be worthwhile to evaluate which ions increase or decrease the reactivity of oxidants. Therefore, a batch system with an excess of target ion was tested. The results showed that ferrous ion increased the reactivity of both PS and PMS. However, chloride ion increased the reactivity of PMS, but it inhibited the reactivity of PS. Moreover, residual concentration of PMS and PS were remained approximately 97~98%, and the pH of system was dramatically reduced when PMS was used. The last of target ions (Mg 2+, Ca 2+, Mn 2+, HCO 3) will be also tested with the condition of an excess.

Ki-man Park; Hong-kyun Lee; Si-hyun Do; Sung-ho Kong

93

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

94

Silver-catalyzed PuO sub 2 dissolution with persulfate  

SciTech Connect

This report consists of 14 slides and associated narrative for a presentation to be given at the 15th Annual Actinide Separations Conference on silver-catalyzed PuO{sub 2} dissolution with persulfate. (JL)

Fisher, F D; Barney, G S; Cooper, T D; Duchsherer, M J

1991-06-01

95

Degradation of toluene-2,4-diamine by persulfate: kinetics, intermediates and degradation pathway.  

PubMed

Abstract In this study, the degradation of toluene-2,4-diamine (TDA) by persulfate (PS) in an aqueous solution at near-neutral pH was examined. The result showed that degradation rate of TDA increased with increasing PS concentrations. The optimal dosage of PS in the reaction system was determined by efficiency indicator (I) coupling in the consumption of PS and decay half-life of TDA. Calculation showed that 0.74?mM of PS was the most effective dosage for TDA degradation, at that level the maximum I of 24.51 was obtained. PS can oxidize TDA for an extended reaction time period. Under neutral condition without activation, four degradation intermediates, 2,4-diamino-3-hydroxy-5-sulfonicacidtoluene, 2,4-diaminobenzaldehyde, 2,4-bis (vinylamino) benzaldehyde, and 3,5-diamino-4-hydroxy-2-pentene were identified by high-performance liquid chromatography-mass spectrometry. The tentative degradation pathway of TDA was proposed as well. It was found that hydroxyl radical played an important role in degradation of TDA with activation of Fe(2+), whereas PS anion and sulfate radicals were responsible for the degradation without activation of Fe(2+). PMID:25442404

Jiang, Yong-Hai; Zhang, Jin-Bao; Xi, Bei-Dou; An, Da; Yang, Yu; Li, Ming-Xiao

2014-12-01

96

PERFORMANCE OF A STIRLING ENGINE POWERED HEAT ACTIVATED HEAT PUMP  

E-print Network

PERFORMANCE 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 for space heating since it directly utilizes the engine waste heat in addition to the energy obtained

Oak Ridge National Laboratory

97

Disinfection of ballast water with iron activated persulfate.  

PubMed

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

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

2013-10-15

98

Heat-activated cooling devices: A guidebook for general audiences  

SciTech Connect

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

Wiltsee, G.

1994-02-01

99

On the Efect of the Oxidative Reagents on the Conductivity of Polyaniline/MMT Nanocomposites  

NASA Astrophysics Data System (ADS)

The synthesis of polyaniline has been reported using three different oxidative reagents: ammonium persulfate, potassium iodate and potassium iodate+sodium hypochlorite. This polyaniline has been used to prepare several nanocomposites with different percentage of Montmorillonite. The DC conductivity of the nanocomposites was determined by impedance spectroscopy. The oxidative reagent that gives higher conductivity is ammonium persulfate. The temperature dependence of the conductivity was studied.

Garcia-Bernabé, A.; Gil-Agustí, M.; Ortega, G.; Llovera, P.; Almarza, A.; Vázquez, S.; Amantia, D.; Aubouy, L.

2010-06-01

100

Oxidation of Aromatic Aldehydes Using Oxone  

ERIC Educational Resources Information Center

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

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

2007-01-01

101

Tight gas sands research program: Field operations and analysis. Degradation of hydroxypropyl guar fracturing fluids by enzyme, oxidative, and catalyzed oxidative breakers. Part 1. Linear hydroxypropyl guar solutions. Topical report, February 1991-December 1991  

SciTech Connect

The research was designed to accomplish the following objectives: Determine the effects of pH, temperature, and polymer concentration on HPG solution degradation by enzyme, oxidative (ammonium persulfate), and catalyzed oxidative breakers (ammonium persulfate with triethanolamine); Identify the appropriate breaker system for HPG solutions in the temperature range of 120 deg F - 140 deg F; and Determine the temperature range for HPG solutions where chemical breakers are not necessary to degrade the fluid.

Craig, D.; Holditch, S.A.

1993-12-01

102

Biochar supported nanoscale zerovalent iron composite used as persulfate activator for removing trichloroethylene.  

PubMed

Biochar (BC) supported nanoscale zerovalent iron (nZVI) composite was synthesized and used as an activator for persulfate to enhance the trichloroethylene (TCE) removal in aqueous solutions. The degradation efficiency of TCE (0.15mmolL(-1)) was 99.4% in the presence of nZVI/BC (4.5mmolL(-1), nZVI to BC mass ratio was 1:5) and persulfate (4.5mmolL(-1)) within 5min, which was significantly higher than that (56.6%) in nZVI-persulfate system under the same conditions. Owing to large specific surface area and oxygen-containing functional groups of BC, nZVI/BC enhanced the SO4(-) generation and accelerated TCE degradation. On the basis of the characterization and analysis data, possible activation mechanisms of the Fe(2+)/Fe(3+) (Fe(II)/Fe(III)) redox action and the electron-transfer mediator of the BC oxygen functional groups promoting the generation of SO4(-) in nZVI/BC-persulfate system were clarified. PMID:25459832

Yan, Jingchun; Han, Lu; Gao, Weiguo; Xue, Song; Chen, Mengfang

2014-10-25

103

The synthesized and thermally modified Mn-Ca-FeOOH composite in persulfate system: Its role to discolor methylene blue  

NASA Astrophysics Data System (ADS)

Methylene blue (MB) discoloration was performed using persulfate (PS) activated with the synthesized composites. Four types of composites, which were synthesized by the immobilization of Mn on iron oxides (hematite and goethite) using either NaOH or Ca(OH)2, were evaluated as PS activator. The synthesized Mn-Ca-FeOOH composite was selected and it was thermally modified at 300 and 700 °C (denoted Mn-Ca-FeOOH_300 and Mn-Ca-FeOOH_700). The BET surface area of Mn-Ca-FeOOH_300 was similar to that of Mn-Ca-FeOOH while that of Mn-Ca-FeOOH_700 was dramatically lower. XRD and XPS analysis indicated that the thermal modification transformed iron oxides from goethite to hematite and changed amorphous manganese oxide to crystalline. MB discoloration at pH 3 indicated that Mn-Ca-FeOOH acted as an oxidant to degrade MB, and the thermally modified composites (i.e. Mn-Ca-FeOOH_300 and Mn-Ca-FeOOH_700) acted as a catalyst to activate PS. Moreover, incomplete MB discoloration was observed in PS/composite system at pH 3. However, a whole tested wavelength of MB was reduced when MB discoloration was tested in PS/composite system above pH 7. Moreover, the increasing pH of solution increased MB discoloration. The higher MB discoloration in heterogeneous system at pH 12 could suggest that superoxide anion (O2•-) was dominant reactive oxygen species.

Jo, Young-Hoon; Hong, Seong-Ho; Park, Tae-Jin; Do, Si-Hyun

2014-05-01

104

Plutonium oxide dissolution  

SciTech Connect

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

Gray, J.H.

1992-09-30

105

Plutonium oxide dissolution  

SciTech Connect

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

Gray, J.H.

1992-09-30

106

Nitroxide mediated living radical polymerization of styrene in miniemulsion—modelling persulfate-initiated systems  

Microsoft Academic Search

Recently we have constructed a mechanistic model describing the nitroxide mediated miniemulsion polymerization (NMMP) of styrene at 135°C, using alkoxyamine initiators to control polymer growth (Nitroxide-Mediated Polymerization of Styrene in Miniemulsion. Modeling Studies of Alkoxyamine-Initiated Systems, 2001b). The model has since been expanded to describe styrene NMMP at 135°C using TEMPO and the free radical initiator, potassium persulfate (KPS). The

John W. Ma; Michael F. Cunningham; Kim B. McAuley; Barkev Keoshkerian; Michael Georges

2003-01-01

107

Reduction of diffusive contaminant emissions from a dissolved source in a lower permeability layer by sodium persulfate treatment.  

PubMed

Residual contamination contained in lower permeability zones is difficult to remediate and can, through diffusive emissions to adjacent higher permeability zones, result in long-term impacts to groundwater. This work investigated the effectiveness of oxidant delivery for reducing diffusive emissions from lower permeability zones. The experiment was conducted in a 1.2 m tall × 1.2 m wide × 6 cm thick tank containing two soil layers having 3 orders of magnitude contrast in hydraulic conductivity. The lower permeability layer initially contained dissolved methyl tert-butyl ether (MTBE) and benzene, toluene, ethylbenzene, and p-xylenes (BTEX). The treatment involved delivery of 10% w/w nonactivated sodium persulfate (Na2S2O8) solution to the high permeability layer for 14 days. The subsequent diffusion into the lower permeability layer and contaminant emission response were monitored for about 240 days. The S2O8(2-) diffused about 14 cm at 1% w/w into the lower permeability layer during the 14 day delivery and continued diffusing deeper into the layer as well as back toward the higher-lower permeability interface after delivery ceased. Over 209 days, the S2O8(2-) diffused 60 cm into the lower permeability layer, the BTEX mass and emission rate were reduced by 95-99%, and the MTBE emission rate was reduced by 63%. The overall treatment efficiency was about 60-110 g-S2O8(2-)delivered/g-hydrocarbon oxidized, with a significant fraction of the oxidant delivered likely lost by back-diffusion and not involved in hydrocarbon destruction. PMID:25386986

Cavanagh, Bridget A; Johnson, Paul C; Daniels, Eric J

2014-12-16

108

Paramagnetic centers in products of the mechanical treatment of potassium persulfate  

SciTech Connect

It was shown that the mechanical breakdown of potassium persulfate at 77/sup 0/K is accompanied by the formation of paramagnetic centers of the types of SO/sub 4//sup -/, SO/sub 5//sup -/, and radical pairs. It was established that heating a mechanically activated sample to 375/sup 0/K leads to an increase in the concentration of paramagnetic centers by more than an order of magnitude. This process is due to breakdown of the (S/sub 2/O/sub 8/)/sup 2 -/ anions and randomization of the structure of the persulfate as a result of mechanical influences. The effects of randomization of the structure of the solid are also manifested in the changes in the form of the ESR spectra of the paramagnetic centers and the increase in the rate of the chemical conversions of the radicals. The direction of the reactions of paramagnetic centers of different structures in potassium persulfate was established, and a radical-chain scheme of thermal decomposition of the substance was proposed on this basis.

Radstig, V.A.; Politov, A.A.

1985-07-01

109

Removal of 2-MIB and geosmin using UV/persulfate: Contributions of hydroxyl and sulfate radicals.  

PubMed

2-methylisoborneol (2-MIB) and geosmin are two odor-causing compounds that are difficult to remove and the cause of many consumer complaints. In this study, we assessed the degradation of 2-MIB and geosmin using a UV/persulfate process for the first time. The results showed that both 2-MIB and geosmin could be degraded effectively using this process. The process was modeled based on steady-state assumption with respect to the odor-causing compounds and either hydroxyl or sulfate radicals. The second order rate constants for 2-MIB and geosmin reacting with the sulfate radical (SO4(-)) were estimated to be (4.2 ± 0.6) × 10(8) M(-1)s(-1) and (7.6 ± 0.6) × 10(8) M(-1)s(-1) respectively at a pH of 7.0. The contributions of the hydroxyl radical (OH) to 2-MIB and geosmin degradation were 3.5 times and 2.0 times higher, respectively, than the contribution from SO4(-) in Milli-Q water with 2 mM phosphate buffer at pH 7.0. The pseudo-first-order rate constants (ko(s)) of both 2-MIB and geosmin increased with increasing dosages of persulfate. Although pH did not affect the degradation of 2-MIB and geosmin directly, different scavenging effects of hydrogen phosphate and dihydrogen phosphate resulted in higher values of ko(s) for both 2-MIB and geosmin in acidic condition. Bicarbonate and natural organic matter (NOM) inhibited the degradation of both 2-MIB and geosmin dramatically through consuming OH and SO4(-) and were likely to be the main radical scavengers in natural waters when using UV/persulfate process to control 2-MIB and geosmin. PMID:25486622

Xie, Pengchao; Ma, Jun; Liu, Wei; Zou, Jing; Yue, Siyang; Li, Xuchun; Wiesner, Mark R; Fang, Jingyun

2014-11-26

110

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

Microsoft Academic Search

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

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

2000-01-01

111

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)(2)S(2)O(8)) 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)(2)S(2)O(8) 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)(2)S(2)O(8), sulfate and hydroxyl free radicals. When (NH4)(2)S(2)O(8) concentration is more than 0.1 mol/L and solution pH is lower than 9.71, Hg(0) removal by thermally activated (NH4)(2)S(2)O(8) meets a pseudo-first-order fast reaction with respect to Hg(0). However, when (NH4)(2)S(2)O(8) 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

112

Friedel-Crafts Amidoalkylation via Thermolysis and Oxidative Photocatalysis  

PubMed Central

Friedel-Crafts amidoalkylation was achieved by oxidation of dialkylamides using persulfate (S2O82?) in the presence of the visible light catalyst, Ru(bpy)3Cl2, at room temperature, via a reactive N-acyliminium intermediate. Alternatively, mild heating of the dialkylamides and persulfate afforded a metal and Lewis acid-free Friedel-Crafts amidoalkylation. Alcohols and electron–rich arenes served as effective nucleophiles, forming new C–O or C–C bonds. In general, photocatalysis provided higher yields and better selectivities. PMID:22458307

Dai, Chunhui; Meschini, Francesco; Narayanam, Jagan M. R.; Stephenson, Corey R. J.

2012-01-01

113

Friedel-Crafts amidoalkylation via thermolysis and oxidative photocatalysis.  

PubMed

Friedel-Crafts amidoalkylation was achieved by oxidation of dialkylamides using persulfate (S(2)O(8)(2-)) in the presence of the visible light catalyst, Ru(bpy)(3)Cl(2), at room temperature, via a reactive N-acyliminium intermediate. Alternatively, mild heating of the dialkylamides and persulfate afforded a metal and Lewis acid-free Friedel-Crafts amidoalkylation. Alcohols and electron-rich arenes served as effective nucleophiles, forming new C-O or C-C bonds. In general, photocatalysis provided higher yields and better selectivities. PMID:22458307

Dai, Chunhui; Meschini, Francesco; Narayanam, Jagan M R; Stephenson, Corey R J

2012-05-01

114

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

Microsoft Academic Search

Determination of total nitrogen in aqueous samples after thermal potassium peroxydisulfate (persulfate) digestion is a commonly used alternative to the tedious Kjeldahl procedure. When ion chromatography is used to quantify the nitrate formed during digestion, there is a potential for interference from a chlorate peak if the digested sample initially contained chloride in concentrations close to or greater than the

Judith A. Halstead; Jessica Edwards; Reginald J. Soracco; Roger W. Armstrong

1999-01-01

115

Persulfate Oxidation Coupled With Microbial Sulfate Reduction as a Combined Remedy.  

E-print Network

??Groundwater contamination by petroleum hydrocarbon (PHC) compounds including the high impact and persistent aromatic compounds such as benzene, toluene, ethyl benzene and xylene (BTEX) poses… (more)

Shayan Moghadam, Mahsa

2015-01-01

116

Water-soluble organic nitrogen in atmospheric aerosol: a comparison of UV and persulfate oxidation methods  

Microsoft Academic Search

Two well established methods that are widely applied in the determination of marine dissolved organic nitrogen (DON) have been investigated in their application to the determination of rainwater DON and the water-soluble organic nitrogen component of atmospheric aerosol. Empirical observation highlighted some difficulties in the analysis of DON in these non-marine matrices, so some practical suggestions for the extension of

S. E Cornell; T. D Jickells

1999-01-01

117

Determination of dissolved organic nitrogen using persulfate oxidation and conductimetric quantification of nitrate?nitrogen  

Microsoft Academic Search

Nitrogen (N) in forest soil extracts and surface waters may be dominantly in organic compounds as dissolved organic nitrogen (DON). Due to various difficulties associated with measuring total N (as TKN) by the Rjeldahl digest, this important vehicle for nutrient movement is rarely monitored. By coupling two relatively new methods and optimizing them for use in soil studies, we developed

Z. S. Yu; R. R. Northup; R. A. Dahlgren

1994-01-01

118

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

119

Diffusion and polymerization of styrene in an aqueous solution of potassium persulfate under static conditions  

SciTech Connect

The potassium persulfate-initiated polymerization of styrene in a mechanically agitated mixture of water and monomer leads to the formation of a stable, monodisperse latex. In order to explain the mechanism of the stabilization of the latex particles in this system, the authors present a detailed investigation of the polymerization of styrene in a specially constructed electrochemical cell under static conditions. A schematic of the cell is shown. Results show that the capacity of the electrical double layer on the platinum electrode remains constant with time in a system containing only a solution of electrolyte, either K/sub 2/SO/sub 4/ or K/sub 2/S/sub 2/O/sub 8/.

Oganesyan, A.A.; Boyadzhyan, V.G.; Gritskova, I.A.; Gukasyan, A.V.; Matsoyan, S.G.; Pravednikov, A.N.

1985-10-01

120

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

Ollé-Monge, Marta; Muñoz, Xavier; Vanoirbeek, Jeroen A. J.; Gómez-Ollés, Susana; Morell, Ferran; Cruz, María-Jesus

2014-01-01

121

Investigation of the toxicity of common oxidants used in advanced oxidation processes and their quenching agents.  

PubMed

The inhibitory effect of commonly known oxidants and their quenching agents was investigated by employing a battery of toxicity tests. Hydrogen peroxide toxicity could be effectively eliminated by the enzyme catalase, whereas sodium thiosulfate and ascorbic acid were recommended as suitable quenching agents for the removal of the oxidants persulfate and peroxymonosulfate in the Vibrio fischeri bioassays. None of the studied quenching agents was found to be suitable for persulfate and peroxymonosulfate in the Daphnia magna bioassays since high inhibitory effects were obtained for both oxidants. In the case of Pseudokirchneriella subcapitata, manganese dioxide powder should be used as an alternative quenching agent to catalase, since this enzyme exhibited a highly toxic effect towards these microalgae. Sodium sulfite, which is extensively used as a quenching agent, was not appropriate for quenching peroxymonosulfate in all studied bioassays. PMID:24996151

Olmez-Hanci, Tugba; Arslan-Alaton, Idil; Dursun, Duygu

2014-08-15

122

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 The development of the first prototype heat activated heat pump (HAHP) jointly sponsored by the Gas Research as a unitary heating and cooling product competing for the same market as is currently served by the gas year

Oak Ridge National Laboratory

123

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

124

Solution polymerization of acrylamide using potassium persulfate as an initiator: kinetic studies, temperature and pH dependence  

Microsoft Academic Search

The kinetics of the radical polymerization of acrylamide in aqueous solution using potassium persulfate as initiator has been investigated by the gravimetric technique. Up to 94% conversion was obtained. The rate of polymerization was governed by the expression at 55°CRpo=k[K2S2O8]0.5[M]01.26The order with respect to initiator was consistent with the classical kinetic rate equation, while the order with respect to monomer

Hong-Ru Lin

2001-01-01

125

In-Situ Chemical Reduction and Oxidation of VOCs in Groundwater: Groundwater Treatability Studies  

NASA Technical Reports Server (NTRS)

This paper presents NASA Marshall Space Flight Center's treatability studies for volatile organic compounds in groundwater. In-Situ groundwater treatment technologies include: 1) Chemical Reduction(Ferox); 2) Chemical Oxidation (Fenton Reagents, Permanganate, and Persulfate); and 3) Thermal (Dynamic Underground Stripping, Six-Phase Heating). This paper is presented in viewgraph form.

Keith, Amy; Glasgow, Jason; McCaleh, Rececca C. (Technical Monitor)

2001-01-01

126

Chemical oxidation of hexachlorocyclohexanes (HCHs) in contaminated soils.  

PubMed

Chemical oxidation of hexachlorocyclohexanes (HCHs) was evaluated in (i) artificially spiked sand with HCH isomers (?, ?, ? and ?) and (ii) contaminated soil sampled from a former gravel pit backfilled with wastes of lindane (?-HCH). Following oxidation treatments were employed: hydrogen peroxide alone (HP), hydrogen peroxide with soluble Fe(II) (Fenton-F), sodium persulfate alone (PS), Fe(II) activated persulfate (AP) and permanganate (PM). GC-MS results revealed a significant degradation of all isomers in spiked soil in the order: F>PS>AP>HP>PM. Soluble Fe(II) enhanced the efficiency of H2O2 but decreased the reactivity of persulfate. Similar trend was observed in contaminated soil, but with less degradation probably caused by scavenging effect of organic matter and soil minerals and/or pollutant unavailability. No significant increase in oxidation efficiency was observed after using availability-enhancement agents in contaminated soil. Other limitation factors (oxidant dose, pH, catalyst type etc.) were also addressed. Among all the isomers tested, ?-HCH was the most recalcitrant one which could be explained by higher metabolic and chemical stability. No by-products were observed by GC-MS regardless of the oxidant used. For being the premier study reporting chemical oxidation of HCH isomers in contaminated soils, it will serve as a base for in-situ treatments of sites contaminated by HCH isomers and other persistent organic pollutants. PMID:24486498

Usman, M; Tascone, O; Faure, P; Hanna, K

2014-04-01

127

Oxidation of trace amounts of transplutonium elements to the tetravalent state in solutions of mineral acids and their stabilities  

SciTech Connect

The behavior of trace amounts of americium(IV) in sulfuric and nitric acid solutions as a function of the mineral acid, potassium phosphotungstate, and ammonium persulfate concentrations was investigated. The stability of americium(IV) was studied. The optimal conditions and time of oxidation of trace amounts of americium to the tetravalent state were found on the basis of the experimental data obtained.

Milyukova, M.S.; Varezhkina, N.S.; Kuzovkina, E.V.; Malikov, D.A.; Myasoedov, B.F.

1989-01-01

128

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

PubMed

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

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

2012-03-01

129

Microbial Dynamics During and After In Situ Chemical Oxidation of Chlorinated Solvents.  

PubMed

In situ chemical oxidation (ISCO) followed by a bioremediation step is increasingly being considered as an effective biphasic technology. Information on the impact of chemical oxidants on organohalide respiring bacteria (OHRB), however, is largely lacking. Therefore, we used quantitative PCR (qPCR) to monitor the abundance of OHRB (Dehalococcoides mccartyi, Dehalobacter, Geobacter, and Desulfitobacterium) and reductive dehalogenase genes (rdh; tceA, vcrA, and bvcA) at a field location contaminated with chlorinated solvents prior to and following treatment with sodium persulfate. Natural attenuation of the contaminants tetrachloroethene (PCE) and trichloroethene (TCE) observed prior to ISCO was confirmed by the distribution of OHRB and rdh genes. In wells impacted by persulfate treatment, a 1 to 3 order of magnitude reduction in the abundances of OHRB and complete absence of rdh genes was observed 21 days after ISCO. Groundwater acidification (pH<3) and increase in the oxidation reduction potential (>500 mV) due to persulfate treatment were significant and contributed to disruption of the microbial community. In wells only mildly impacted by persulfate, a slight stimulation of the microbial community was observed, with more than 1 order of magnitude increase in the abundance of Geobacter and Desulfitobacterium 36 days after ISCO. After six months, regeneration of the OHRB community occurred, however, neither D. mccartyi nor any rdh genes were observed, indicating extended disruption of biological natural attenuation (NA) capacity following persulfate treatment. For full restoration of biological NA activity, additional time may prove sufficient; otherwise addition electron donor amendment or bioaugmentation may be required. PMID:24898385

Sutton, Nora B; Atashgahi, Siavash; van der Wal, Jurgen; Wijn, Geert; Grotenhuis, Tim; Smidt, Hauke; Rijnaarts, Huub H M

2014-06-01

130

Groundwater Sampling at ISCO Sites: Binary Mixtures of Volatile Organic Compounds and Persulfate  

EPA Science Inventory

In-situ chemical oxidation involves the introduction of a chemical oxidant into the subsurface for the purpose of transforming ground-water contaminants into less harmful byproducts. Due to oxidant persistence, ground water samples collected at hazardous waste sites may contain o...

131

Oxygen-18 study of the mechanism of promoter action of thiocyanate ions in the electrosynthesis of persulfuric acid and ammonium persulfate at platinum anodes  

SciTech Connect

The authors use labelled oxygen to study the involvement of water and sulfate ions in molecular oxygen evolution during the anodic synthesis of persulfuric acid and ammonium persulfate at a platinum anode in an electrolytic cell with and without thiocyanate as a promoter for the electrocatalytic reaction.

Kasatkin, E.V.; Larchenko, L.I.; Potapova, G.F.

1987-02-01

132

Adsorption of chromium(VI) and nickel(II) ions on acid- and heat-activated deoiled spent bleaching clay  

Microsoft Academic Search

De-oiled spent bleaching clay was activated either by acid treatment followed by heat activation or by heat activation alone\\u000a at temperatures between 200 and 800C. The surface area of the heat-activated clay attained a maximal value of ?120 m2 g?1 at temperatures between 400 and 500C while the acid-heat-treated clay attained maximal surface area of ?140 m2 g?1. The adsorption

C. E. Seng; C. G. Lee; K. Y. Liew

2001-01-01

133

Performance of a combined organic Rankine cycle and vapor compression cycle for heat activated cooling  

Microsoft Academic Search

Heat activated cooling has the potential of utilizing thermal sources that currently go unused such as engine exhaust heat or industrial waste heat. Using these heat sources can provide enhanced energy utilization and reduced fuel usage in applications where cooling is needed. The concept developed here uses waste heat from stationary and mobile engine cycles to generate cooling for structures

Hailei Wang; Richard Peterson; Kevin Harada; Erik Miller; Robbie Ingram-Goble; Luke Fisher; James Yih; Chris Ward

2011-01-01

134

[The significance of heat activation for the testing of bioindicators on surviving microorganisms exposed to formaldehyde].  

PubMed

Heat activation is a special phenomenon: After an additional heat treatment, a larger share of the bacterial spores which had been exposed to formaldehyde proves to be viable than without such heat activation. Model studies have been performed to test the effects of heat activation on the examination of bioindicators and test objects for surviving organisms. Test objects (cotton threads of 1 cm length) contaminated with spores of Bacillus stearothermophilus were used for these trials. The test objects were exposed to a 2% formaldehyde solution at 60 degrees C. After periods of action of 30, 45, 60 ... and 105 min, formaldehyde adhering to the test objects was neutralized. For testing these objects for surviving organisms, they were placed into a nutrient medium and incubated for 40 days at 56 degrees C. The investigation consisted of 2 parallel test series which only differed in one single point. In one series, the test objects were incubated at 56 degrees C as soon as they had been placed into the nutrient solution. In the other series, the test objects were exposed to a temperature of 95 degrees C for 1 h (heat activation) before starting incubation. The culture tubes were checked daily to see whether signs of growth (turbidity and deposits) could be observed. The frequencies of test objects with surviving organisms depending on the period of action of formaldehyde and the period of incubation determined in this way are based on the examination of 72 test objects each. Without heat activation, the share of test objects on which surviving test organisms could be detected, increased slowly with the period of incubation. Only after 30 days the counts did not increase any more when continuing the incubation (cf. Fig. 1). In the test series in which the spores had been subjected to heat activation before the incubation period, useful results were obtained already after 3 days. They only changed slightly when incubation was continued. Moreover, the frequency of test objects on which surviving organisms could be detected was always considerably higher than without heat activation. When the frequency of test objects with surviving organisms was plotted against the period of action of formaldehyde (cf. Fig. 2A), S-shaped curves resulted.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:3138833

Spicher, G; Borchers, U

1988-05-01

135

Geochemical and microbiological characteristics during in situ chemical oxidation and in situ bioremediation at a diesel contaminated site.  

PubMed

While in situ chemical oxidation with persulfate has seen wide commercial application, investigations into the impacts on groundwater characteristics, microbial communities and soil structure are limited. To better understand the interactions of persulfate with the subsurface and to determine the compatibility with further bioremediation, a pilot scale treatment at a diesel-contaminated location was performed consisting of two persulfate injection events followed by a single nutrient amendment. Groundwater parameters measured throughout the 225 day experiment showed a significant decrease in pH and an increase in dissolved diesel and organic carbon within the treatment area. Molecular analysis of the microbial community size (16S rRNA gene) and alkane degradation capacity (alkB gene) by qPCR indicated a significant, yet temporary impact; while gene copy numbers initially decreased 1-2 orders of magnitude, they returned to baseline levels within 3 months of the first injection for both targets. Analysis of soil samples with sequential extraction showed irreversible oxidation of metal sulfides, thereby changing subsurface mineralogy and potentially mobilizing Fe, Cu, Pb, and Zn. Together, these results give insight into persulfate application in terms of risks and effective coupling with bioremediation. PMID:24450862

Sutton, Nora B; Kalisz, Mariusz; Krupanek, Janusz; Marek, Jan; Grotenhuis, Tim; Smidt, Hauke; de Weert, Jasperien; Rijnaarts, Huub H M; van Gaans, Pauline; Keijzer, Thomas

2014-02-18

136

Adiabatic polymerization of acrylamide in water under the effect of the potassium persulfate-sodium metabisulfite-copper sulfate system  

SciTech Connect

Since adiabatic polymerization of acrylamide (AA) has been studied very little and the information on the effect of copper ions on polymerization of AA prepared in dilute aqueous solutions is very limited, the features of adiabatic polymerization of AA in concentrated aqueous solutions in the presence of the potassium persulfate-sodium metabisulfite-copper sulfate redox initiating system were investigated in this study. The empirical equation for the overall rate of adiabatic polymerization of acrylamide in concentrated aqueous solutions was found, and the effective total activation energy, which decreases with an increase in the concentration of CuSO/sub 4/, was determined. An increase in the molecular weight of the polymer with an increase in the concentration of the monomer and a decrease in the concentration of the components of the initiating system was demonstrated.

Kurenkov, V.F.; Baiburdov, T.A.; Stupen'kova, L.L.

1988-04-10

137

Simultaneous determination of total nitrogen and total phosphorus in environmental waters using alkaline persulfate digestion and ion chromatography.  

PubMed

An ion chromatography (IC) method was developed for the simultaneous determination of total nitrogen and total phosphorus after alkaline persulfate digestion. This study takes advantage of advances in construction of high-resolution, high-capacity anion-exchange columns that can better tolerate the matrices typically encountered when a determination of total nitrogen and total phosphorous is required. Here, we used an electrolytically generated hydroxide eluent combined with a high-capacity, hydroxide-selective, anion-exchange column for the determination of total nitrogen (as nitrate-N) and total phosphorus (as phosphate-P) in environmental samples by IC. This method yielded LODs for nitrate-N and phosphate-P of 1.0 and 1.3 ?g/L, respectively. The LOQs determined for these analytes were 3.4 and 4.2 ?g/L, respectively. Due to the dilution factor required and the blank nitrate-N concentration after the persulfate digestion, the quantification limits increased for nitrate-N and phosphate-P to 171 and 63 ?g/L, respectively. The suitability of the method was evaluated by determining the nitrogen and phosphorus concentrations from known concentrations of organic-containing nitrogen and phosphorus compounds. In addition, environmental samples consisting of six different wastewaters and 48 reservoir samples were evaluated for total nitrogen and phosphorus. The recoveries of nitrogen and phosphorus from the organic-containing compounds ranged from 93.1 to 100.1% and 85.2 to 97.1%, respectively. In addition, good correlation between results obtained by the colorimetric method and IC was also observed. The linearity, accuracy, and evaluation of potential interferences for determining TN and TP will be discussed. PMID:25441080

De Borba, Brian M; Jack, Richard F; Rohrer, Jeffrey S; Wirt, Joan; Wang, Dongmei

2014-11-21

138

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

139

Divalent cations potentiate TRPV1 channel by lowering the heat activation threshold  

PubMed Central

Transient receptor potential vanilloid type 1 (TRPV1) channel responds to a wide spectrum of physical and chemical stimuli. In doing so, it serves as a polymodal cellular sensor for temperature change and pain. Many chemicals are known to strongly potentiate TRPV1 activation, though how this is achieved remains unclear. In this study we investigated the molecular mechanism underlying the gating effects of divalent cations Mg2+ and Ba2+. Using a combination of fluorescence imaging and patch-clamp analysis, we found that these cations potentiate TRPV1 gating by most likely promoting the heat activation process. Mg2+ substantially lowers the activation threshold temperature; as a result, a significant fraction of channels are heat-activated at room temperature. Although Mg2+ also potentiates capsaicin- and voltage-dependent activation, these processes were found either to be not required (in the case of capsaicin) or insufficient (in the case of voltage) to mediate the activating effect. In support of a selective effect on heat activation, Mg2+ and Ba2+ cause a Ca2+-independent desensitization that specifically prevents heat-induced channel activation but does not prevent capsaicin-induced activation. These results can be satisfactorily explained within an allosteric gating framework in which divalent cations strongly promote the heat-dependent conformational change or its coupling to channel activation, which is further coupled to the voltage- and capsaicin-dependent processes. PMID:24344247

Cao, Xu; Ma, Linlin; Yang, Fan

2014-01-01

140

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

SciTech Connect

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

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

2004-01-23

141

Styrene\\/potassium persulfate\\/water systems: effects of hydrophilic comonomers and solvent additives on the nucleation mechanism and the particle size  

Microsoft Academic Search

Emulsifier-free emulsion polymerizations based on styrene\\/potassium persulfate\\/water (St\\/kps\\/H2O) in the presence of a relatively hydrophilic comonomer, such as vinyl acetate (VAc) or methyl methacrylate (MMA), or the nonpolar solvent, such as ethyl acetate (EAc) or methyl isobutyrate (MIB) having structural similarity with VAc and MMA respectively, or the polar solvent such as glycerin or acetone etc., have been carried out.

Jinn-Luh Ou; Jia-Kuen Yang; Hui Chen

2001-01-01

142

Oxidation of trivalent americium, curium, and terbium in solutions of sodium paratungstate  

SciTech Connect

In the further study of the behavior of the actinides and lanthanides in solutions of heteropoly-compounds, the authors succeed in finding conditions under which the formation of americium (IV), curium (IV), and terbium (IV) decatungstates is observed. The results of experiments along this line are brieflyoutlined. It is shown that trivalent americium, curium, and terbium are oxidzed by heating with persulfate not only in solutions ofunsaturated heteropolytungstates but also in solutions of isopoly-compounds of tungsten. However, the degree of oxidation of curium and terbium (III) in the latter case is appreciably lover. In addition to persulfate ions, ozone can be used for the oxidation of americium (III) in solutions of sodium paratungstate.

Fedoseev, A.M.; Krot, N.N.; Spitsyn, V.I.

1986-09-01

143

Preparation and properties of a compound containing nickel in highest oxidation states  

SciTech Connect

The purpose of this paper is to obtain nickel hydroxide oxide of the optimal composition both by chemical and by electrochemical oxidation for use as the cathode material in alkaline batteries. The authors selected the oxidation conditions (oxidant, component ratio) for production of gamma-NiOOH; hydrogen peroxide, potassium permanganate, and potassium persulfate were used as oxidants. Gamma-NiOOH was also obtained by electrochemical oxidation of nickel (II) oxide hydrate in alkaline solutions. In samples obtained by electrochemical oxidation virtually 100% of the nickel is in the highly oxidized state. It is shown that gamma-NiOOH obtained by both chemical and electrochemical oxidation is a complex individual compound containing nickel and in the highest oxidation states, Ni/sup 3 +/ and Ni/sup 4 +/, together with salt-forming potassium ions and water molecules. The gamma-NiOOH obtained may be used with success in galvanic cells.

Nikol'skii, V.A.; Bekreneva, L.A.; Garmash, L.A.; Makashev, Yu.A.; Mikhailova, K.A.; Raikhel'son, L.B.; Shchelkunova, L.I.

1986-04-10

144

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory : evaluation of alkaline persulfate digestion as an alternative to Kjeldahl digestion for determination of total and dissolved nitrogen and phosphorus in water  

USGS Publications Warehouse

Alkaline persulfate digestion was evaluated and validated as a more sensitive, accurate, and less toxic alternative to Kjeldahl digestion for routine determination of nitrogen and phosphorus in surface- and ground-water samples in a large-scale and geographically diverse study conducted by U.S. Geological Survey (USGS) between October 1, 2001, and September 30, 2002. Data for this study were obtained from about 2,100 surface- and ground-water samples that were analyzed for Kjeldahl nitrogen and Kjeldahl phosphorus in the course of routine operations at the USGS National Water Quality Laboratory (NWQL). These samples were analyzed independently for total nitrogen and total phosphorus using an alkaline persulfate digestion method developed by the NWQL Methods Research and Development Program. About half of these samples were collected during nominally high-flow (April-June) conditions and the other half were collected during nominally low-flow (August-September) conditions. The number of filtered and whole-water samples analyzed from each flow regime was about equal.By operational definition, Kjeldahl nitrogen (ammonium + organic nitrogen) and alkaline persulfate digestion total nitrogen (ammonium + nitrite + nitrate + organic nitrogen) are not equivalent. It was necessary, therefore, to reconcile this operational difference by subtracting nitrate + nitrite concentra-tions from alkaline persulfate dissolved and total nitrogen concentrations prior to graphical and statistical comparisons with dissolved and total Kjeldahl nitrogen concentrations. On the basis of two-population paired t-test statistics, the means of all nitrate-corrected alkaline persulfate nitrogen and Kjeldahl nitrogen concentrations (2,066 paired results) were significantly different from zero at the p = 0.05 level. Statistically, the means of Kjeldahl nitrogen concentrations were greater than those of nitrate-corrected alkaline persulfate nitrogen concentrations. Experimental evidence strongly suggests, however, that this apparent low bias resulted from nitrate interference in the Kjeldahl digestion method rather than low nitrogen recovery by the alkaline persulfate digestion method. Typically, differences between means of Kjeldahl nitrogen and nitrate-corrected alkaline persulfate nitrogen in low-nitrate concentration (< 0.1 milligram nitrate nitrogen per liter) subsets of filtered surface- and ground-water samples were statistically equivalent to zero at the p =level.Paired analytical results for dissolved and total phosphorus in Kjeldahl and alkaline persulfate digests were directly comparable because both digestion methods convert all forms of phosphorus in water samples to orthophosphate. On the basis of two-population paired t-test statistics, the means of all Kjeldahl phosphorus and alkaline persulfate phosphorus concentrations (2,093 paired results) were not significantly different from zero at the p = 0.05 level. For some subsets of these data, which were grouped according to water type and flow conditions at the time of sample collection, differences between means of Kjeldahl phosphorus and alkaline persulfate phosphorus concentrations were not equivalent to zero at the p = 0.05 level. Differences between means of these subsets, however, were less than the method detection limit for phosphorus (0.007 milligram phosphorus per liter) by the alkaline persulfate digestion method, and were therefore analytically insignificant.This report provides details of the alkaline persulfate digestion procedure, interference studies, recovery of various nitrogen- and phosphorus-containing compounds, and other analytical figures of merit. The automated air-segmented continuous flow methods developed to determine nitrate and orthophosphate in the alkaline persulfate digests also are described. About 125 microliters of digested sample are required to determine nitrogen and phosphorus in parallel at a rate of about 100 samples per hour with less than 1-percent sample in

Patton, Charles J.; Kryskalla, Jennifer R.

2003-01-01

145

Experimental Evaluation of Catalyzed Hydrogen Peroxide and Sodium Persulfate for Destruction of BTEX Contaminants  

Microsoft Academic Search

Due to the toxicity and prevalence of BTEX contaminants (benzene, toluene, ethylbenzene, and xylenes) at hazardous waste sites, approaches for their remediation are of interest, especially those that particularly address benzene, which is often the limiting factor for achieving regulatory cleanup at these contaminated sites. In situ chemical oxidation (ISCO) is a viable technology for BTEX destruction, and hydrogen peroxide

Michelle L. Crimi; Jesse Taylor

2007-01-01

146

Simultaneous determination of total nitrogen and total phosphorus in freshwater samples using persulfate digestion  

Microsoft Academic Search

The accuracy and precision of total nitrogen (T?N) and total phosphorus (T?P) determinations in freshwater samples by the simultaneous digestion method using an oxidizing reagent solution of NaOH?K2S2O8 were assessed. Detection limits based on the blank test of nitrogen and phosphorus were 0.02 mgN\\/1 and 0.001 mgP\\/1, respectively. This simultaneous digestion method gave not only a high recovery and reproducibility

Masaaki Hosomi; Ryuichi Sudo

1986-01-01

147

Degradation of acetic acid with sulfate radical generated by persulfate ions photolysis  

Microsoft Academic Search

The photolysis of S2O82- was studied for the removal of acetic acid in aqueous solution and compared with the H2O2\\/UV system. The SO4- radicals generated from the UV irradiation of S2O82- ions yield a greater mineralization of acetic acid than the OH radicals. Acetic acid is oxidized by SO4- radicals without significant formation of intermediate by-products. Increasing system pH results

Justine Criquet; Nathalie Karpel Vel Leitner

2009-01-01

148

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

149

Tissue Engineering: Fabrication of Anisotropic Neurodurable Scaffold via Molecular Disposition of Persulfate-Mediated Polymer Slicing and Complexation  

E-print Network

Abstract: Macroporous polyacrylamide-grafted-chitosan scaffolds for neural tissue engineering were fabricated with varied synthetic and viscosity profiles. A novel approach and mechanism was utilized for polyacrylamide grafting onto chitosan using potassium persulfate (KPS) mediated degradation of both polymers under a thermally controlled environment. Commercially available high molecular mass polyacrylamide was used instead of the acrylamide monomer for graft copolymerization. This grafting strategy yielded an enhanced grafting efficiency (GE = 92%), grafting ratio (GR = 263%), intrinsic viscosity (IV = 5.231 dL/g) and viscometric average molecular mass (MW = 1.63 × 10 6 Da) compared with known acrylamide that has a GE = 83%, GR = 178%, IV = 3.901 dL/g and MW = 1.22 × 10 6 Da. Image processing analysis of SEM images of the newly graftedInt. J. Mol. Sci. 2012, 13 13967 neurodurable scaffold was undertaken based on the polymer-pore threshold. Attenuated Total Reflectance-FTIR spectral analyses in conjugation with DSC were used for the

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

2012-01-01

150

Exploration of the role of heat activation in enhancing serpentine carbon sequestration reactions.  

PubMed

As compared with other candidate carbon sequestration technologies, mineral carbonation offers the unique advantage of permanent disposal via geologically stable and environmentally benign carbonates. The primary challenge is the development of an economically viable process. Enhancing feedstock carbonation reactivity is key. Heat activation dramatically enhances aqueous serpentine carbonation reactivity. Although the present process is too expensive to implement, the materials characteristics and mechanisms that enhance carbonation are of keen interest for further reducing cost. Simultaneous thermogravimetric and differential thermal analysis (TGA/DTA) of the serpentine mineral lizardite was used to isolate a series of heat-activated materials as a function of residual hydroxide content at progressively higher temperatures. Their structure and composition are evaluated via TGA/DTA, X-ray powder diffraction (including phase analysis), and infrared analysis. The meta-serpentine materials that were observed to form ranged from those with longer range ordering, consistent with diffuse stage-2 like interlamellar order, to an amorphous component that preferentially forms at higher temperatures. The aqueous carbonation reaction process was investigated for representative materials via in situ synchrotron X-ray diffraction. Magnesite was observed to form directly at 15 MPa CO2 and at temperatures ranging from 100 to 125 degrees C. Carbonation reactivity is generally correlated with the extent of meta-serpentine formation and structural disorder. PMID:15669355

McKelvy, Michael J; Chizmeshya, Andrew V G; Diefenbacher, Jason; Béarat, Hamdallah; Wolf, George

2004-12-15

151

Activating persulfate by Fe? coupling with weak magnetic field: performance and mechanism.  

PubMed

Weak magnetic field (WMF) and Fe(0) were proposed to activate PS synergistically (WMF-Fe(0)/PS) to degrade dyes and aromatic contaminants. The removal rates of orange G (OG) by WMF-Fe(0)/PS generally decreased with increasing initial pH (3.0-10.0) and increased with increasing Fe(0) (0.5-3.0 mM) or PS dosages (0.5-3.0 mM). Compared to its counterpart without WMF, the WMF-Fe(0)/PS process could induce a 5.4-28.2 fold enhancement in the removal rate of OG under different conditions. Moreover, the application of WMF significantly enhanced the decolorization rate and the mineralization of OG. The degradation rates of caffeine, 4-nitrophenol, benzotriazole and diuron by Fe(0)/PS were improved by 2.1-11.1 fold due to the superimposed WMF. Compared to many other sulfate radical-based advanced oxidation technologies under similar reaction conditions, WMF-Fe(0)/PS technology could degrade selected organic contaminants with much greater rates. Sulfate radical was identified to be the primary radical species responsible for the OG degradation at pH 7.0 in WMF-Fe(0)/PS process. This study unraveled that the presence of WMF accelerated the corrosion rate of Fe(0) and thus promoted the release of Fe(2+), which induced the increased production of sulfate radicals from PS and promoted the degradation of organic contaminants. Employing WMF to enhance oxidation capacity of Fe(0)/PS is a novel, efficient, promising and environmental-friendly method since it does not need extra energy and costly reagents. PMID:24934323

Xiong, Xinmei; Sun, Bo; Zhang, Jing; Gao, Naiyun; Shen, Jimin; Li, Jialing; Guan, Xiaohong

2014-10-01

152

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

153

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

PubMed Central

Macroporous polyacrylamide-grafted-chitosan scaffolds for neural tissue engineering were fabricated with varied synthetic and viscosity profiles. A novel approach and mechanism was utilized for polyacrylamide grafting onto chitosan using potassium persulfate (KPS) mediated degradation of both polymers under a thermally controlled environment. Commercially available high molecular mass polyacrylamide was used instead of the acrylamide monomer for graft copolymerization. This grafting strategy yielded an enhanced grafting efficiency (GE = 92%), grafting ratio (GR = 263%), intrinsic viscosity (IV = 5.231 dL/g) and viscometric average molecular mass (MW = 1.63 × 106 Da) compared with known acrylamide that has a GE = 83%, GR = 178%, IV = 3.901 dL/g and MW = 1.22 × 106 Da. Image processing analysis of SEM images of the newly grafted neurodurable scaffold was undertaken based on the polymer-pore threshold. Attenuated Total Reflectance-FTIR spectral analyses in conjugation with DSC were used for the characterization and comparison of the newly grafted copolymers. Static Lattice Atomistic Simulations were employed to investigate and elucidate the copolymeric assembly and reaction mechanism by exploring the spatial disposition of chitosan and polyacrylamide with respect to the reactional profile of potassium persulfate. Interestingly, potassium persulfate, a peroxide, was found to play a dual role initially degrading the polymers—“polymer slicing”—thereby initiating the formation of free radicals and subsequently leading to synthesis of the high molecular mass polyacrylamide-grafted-chitosan (PAAm-g-CHT)—“polymer complexation”. Furthermore, the applicability of the uniquely grafted scaffold for neural tissue engineering was evaluated via PC12 neuronal cell seeding. The novel PAAm-g-CHT exhibited superior neurocompatibility in terms of cell infiltration owing to the anisotropic porous architecture, high molecular mass mediated robustness, superior hydrophilicity as well as surface charge due to the acrylic chains. Additionally, these results suggested that the porous PAAm-g-CHT scaffold may act as a potential neural cell carrier. PMID:23203044

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

2012-01-01

154

Alkene oxidation catalyzed by a ruthenium-substituted heteropolyanion, SiRu(L)W sub 11 O sub 39 : The mechanism of the periodate mediated oxidative cleavage  

SciTech Connect

A ruthenium-substituted heteropolyanion SiRu(H{sub 2}O)W{sub 11}O{sub 39}{sup 5{minus}} was synthesized and characterized. The hydrophobic quaternary ammonium salt of the heteropolyanion ((C{sub 6}H{sub 13}){sub 4}N){sub 5}SiRu{sup III}(H{sub 2}O)W{sub 11}O{sub 39} was used as a catalyst for the oxidation of alkenes with tert-butyl hydroperoxide, potassium persulfate, iodosobenzene, and sodium periodate as primary oxidants. Reactivity and selectivity were found to be dependent on the oxidant used; several different types of oxidation processes could be identified including allylic oxidation, epoxidation, and oxidative cleavage. Use of sodium periodate as oxidant enabled selective bond cleavage with aldehydes as the exclusive product.

Neumann, R.; Abu-Gnim, C. (Hebrew Univ. of Jerusalem (Israel))

1990-08-01

155

Evaluation of a Stochastic Inactivation Model for Heat-Activated Spores of Bacillus spp. ?  

PubMed Central

Heat activates the dormant spores of certain Bacillus spp., which is reflected in the “activation shoulder” in their survival curves. At the same time, heat also inactivates the already active and just activated spores, as well as those still dormant. A stochastic model based on progressively changing probabilities of activation and inactivation can describe this phenomenon. The model is presented in a fully probabilistic discrete form for individual and small groups of spores and as a semicontinuous deterministic model for large spore populations. The same underlying algorithm applies to both isothermal and dynamic heat treatments. Its construction does not require the assumption of the activation and inactivation kinetics or knowledge of their biophysical and biochemical mechanisms. A simplified version of the semicontinuous model was used to simulate survival curves with the activation shoulder that are reminiscent of experimental curves reported in the literature. The model is not intended to replace current models to predict dynamic inactivation but only to offer a conceptual alternative to their interpretation. Nevertheless, by linking the survival curve's shape to probabilities of events at the individual spore level, the model explains, and can be used to simulate, the irregular activation and survival patterns of individual and small groups of spores, which might be involved in food poisoning and spoilage. PMID:20453137

Corradini, Maria G.; Normand, Mark D.; Eisenberg, Murray; Peleg, Micha

2010-01-01

156

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

157

Development and demonstration of a Stirling/Rankine heat activated heat pump. Phase IIIB. Engine technology development testing. Final report  

SciTech Connect

This report presents the results of the Phase II and Phase IIIB Stirling/Rankine Heat Activated Heat Pump product development program. In the Phase II program, a complete gas fired heat activated prototype residential heat pump system was developed and tested. Results of the Phase II program indicated deficiencies in the performance of the free-piston Stirling engine and mismatching of the dynamic characteristics of the engine and the compressor. These deficiencies were further investigated during in-depth diagnostic testing of the engine/compressor unit in the Phase IIIB program. Results of these tests identified the engine design deficiencies and indicated appropriate engine/compressor matching criteria. The Phase IIIB results are presented in Volume III of this report.

Not Available

1984-04-09

158

Development and demonstration of a Stirling/Rankine heat activated heat pump. Volume 1. Phase 2. Product development program. Final report  

SciTech Connect

This report presents the results of the Phase II and Phase IIIB Stirling/Rankine Heat Activated Heat Pump product development program. In the Phase II program, a complete gas fired heat activated prototype residential heat pump system was developed and tested. Results of the product system development are presented in Volume I of this report, emphasizing the key components of the system: the free piston Stirling engine prime mover and the free piston linear inertia compressor.

Not Available

1984-04-25

159

Development and demonstration of a Stirling/Rankine Heat Activated Heat Pump. Phase IIIB. Engine technology development testing. Final report  

SciTech Connect

This report presents the results of the Phase IIIB Stirling/Rankine Heat Activated Heat Pump product development program. Results of the Phase II program indicated deficiencies in the performance of the free-piston Stirling engine and mismatching of the dynamic characteristics of the engine and the compressor. These deficiencies were further investigated during in-depth diagnostic testing of the engine/compressor unit in the Phase IIIB program. Results of these tests identified the engine design deficiencies and indicated appropriate engine/compressor matching criteria. The Phase IIIB results are presented.

Not Available

1984-11-01

160

oxidation of americium(iii) and the stability of americium(iv) and americium(vi) in solutions of sulfuric and perchloric acids  

SciTech Connect

The oxidation of weighable amounts of americium in solutionsof sulfuric and perchloric acids was investigated by a spectrophotometric method. The stability of americium(IV) and (VI) in mineral acids was studied. A method was developed for the production of tetravalent americium in solutions of 0.1-3 M H/sub 2/SO/sub 4/ and 0.1-1 M HClO/sub 4/, containing potassium phosphotungstate K/sub 10/P/sub 2/W/sub 17/O/sub 61/ an an oxidizing mixture - a silver salt and ammonium persulfate.

Milyukova, M.S.; Litvina, M.N.; Myasoedov, B.F.

1986-07-01

161

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

162

Incipient hydrous oxide species as inhibitors of reduction processes at noble metal electrode  

SciTech Connect

Evidence is presented to illustrate the important role of hydrous oxide in noble metal electrocatalysis. It was demonstrated, for instance, that in the case of gold in acid the onset/termination potential, under potential sweep conditions, for hydrazine oxidation and persulfate or iodate reduction occurred at the end of the hydrous oxide reduction peak (recorded for a thick film growth grown by potential multicycling); there was also a maximum in the faradaic ac response for gold in acid in the same region. Both gold and platinum were investigated in acid and base electrolytes. In some cases a range of potential, rather than a discrete value, was found to be involved, different species react with (or are inhibited by) different types (or coverages) of these submonolayer species. In some, possibly electrocatalytically nondemanding, reduction reactions the hydrous oxide seemed to have little effect.

Burke, L.D.; O'Sullivan, J.F.; O'Dwyer, K.J.; Scannell, R.A.; Ahern, M.J.G.; McCarthy, M.M. (Dept. of Chemistry, Univ. College, Cork (IE))

1990-08-01

163

Process for the oxidation of materials in water at supercritical temperatures utilizing reaction rate enhancers  

SciTech Connect

A method is described for substantially completely oxidizing combustible materials in which an aqueous stream bearing the combustible materials is reacted in the presence of an oxidant comprising diatomic oxygen and at a temperature greater than the critical temperature of water and at a pressure greater than about 25 bar, within a reactor for a period of less than about 5 minutes to produce a reaction product stream, wherein the reaction is initiated in the presence of a rate enhancer comprising at least one oxidizing agent in addition to said oxidant selected from the group consisting of ozone, hydrogen peroxide, salts containing persulfate, salts containing permanganate, nitric acid, salts containing nitrate, oxyacids of chlorine and their corresponding salts, hypochlorous acid, salts containing hypochlorite, chlorous acid, salts containing chlorite, chloric acid, salts containing chlorate, perchloric acid, and salts containing perchlorate.

Swallow, K.C.; Killilea, W.R.; Hong, G.T.; Bourhis, A.L.

1993-08-03

164

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

165

Probing the radical chemistry in UV/persulfate-based saline wastewater treatment: kinetics modeling and byproducts identification.  

PubMed

The effect of Cl(-) on the oxidative degradation of Acid Orange 7 (AO7) was investigated in UV/S2O8(2-) system to elucidate the chlorination pathways in saline wastewaters. Lower amount of Cl(-) as well as Br(-) enhanced the decoloration of AO7, but such promotion effect reduced gradually with the increasing halide ion dosage. The dye mineralization was found to be inhibited by Cl(-), especially under acidic conditions. Results of kinetics modeling demonstrated that the fraction of different oxidizing radicals largely depended on the content of Cl(-). At the initial pH of 6.5, Cl2(-) was much more abundant than SO4(-). The significance of Cl2(-) for AO7 degradation increased with the increasing Cl(-) concentration and overwhelmed that of SO4(-) at [Cl(-)]>1mM. Without Cl(-), SO4(-) was the predominant radical for AO7 degradation under acidic conditions, while OH prevailed gradually at higher pH. Under high salinity conditions, more OH can be formed and contributed to the dye degradation especially in alkaline medium, leading to higher destruction efficiency of AO7. Several chlorinated byproducts were detected in the presence of chloride ions, and SO4(-)/Cl2(-)-based degradation pathways of AO7 were proposed. This work provides further understanding of the complex reaction mechanisms for SO4(-)-based advanced oxidation processes in chloride-rich environments. PMID:24873714

Yuan, Ruixia; Wang, Zhaohui; Hu, Yin; Wang, Baohui; Gao, Simeng

2014-08-01

166

Generating bifunctional fusion enzymes composed of heat-active endoglucanase (Cel5A) and endoxylanase (XylT).  

PubMed

Bifunctional enzyme constructs were generated comprising two genes encoding heat-active endoglucanase (cel5A) and endoxylanase (xylT). The fused proteins Cel5A-XylT and XylT-Cel5A were active on both ?-glucan and beechwood xylan. An improvement in endoglucanase and endoxylanase catalytic activities was observed. The specific activity of the fusion towards xylan was significantly raised when compared to XylT. The fusion constructs were active from 40 to 100 °C for endoglucanase and from 40 to 90 °C for endoxylanase, but the temperature optima were lowered from 90 to 80 °C for the endoglucanase and from 80 to 70 °C for the endoxylanase. XylT in the construct XylT-Cel5A was less stable at higher temperatures compared to Cel5A-XylT. Due to the enzymatic performance, these fusion enzymes are attractive candidates for applications in biorefineries based on plant waste. PMID:25214221

Rizk, Mazen; Elleuche, Skander; Antranikian, Garabed

2015-01-01

167

Effects of chemical oxidants on perfluoroalkyl Acid transport in one-dimensional porous media columns.  

PubMed

In situ chemical oxidation (ISCO) is a remediation approach that is often used to remediate soil and groundwater contaminated with fuels and chlorinated solvents. At many aqueous film-forming foam-impacted sites, perfluoroalkyl acids (PFAAs) can also be present at concentrations warranting concern. Laboratory experiments were completed using flow-through one-dimensional columns to improve our understanding of how ISCO (i.e., activated persulfate, permanganate, or catalyzed hydrogen peroxide) could affect the fate and transport of PFAAs in saturated porous media. While the resultant data suggest that standard ISCO is not a viable remediation strategy for PFAA decomposition, substantial changes in PFAA transport were observed upon and following the application of ISCO. In general, activated persulfate decreased PFAA transport, while permanganate and catalyzed hydrogen peroxide increased PFAA transport. PFAA sorption increased in the presence of increased aqueous polyvalent cation concentrations or decreased pH. The changes in contaminant mobility were greater than what would be predicted on the basis of aqueous chemistry considerations alone, suggesting that the application of ISCO results in changes to the porous media matrix (e.g., soil organic matter quality) that also influence transport. The application of ISCO is likely to result in changes in PFAA transport, where the direction (increased or decreased transport) and magnitude are dependent on PFAA characteristics, oxidant characteristics, and site-specific factors. PMID:25621878

McKenzie, Erica R; Siegrist, Robert L; McCray, John E; Higgins, Christopher P

2015-02-01

168

Study of water adsorption on activated carbons with different degrees of surface oxidation  

SciTech Connect

A carbon of wood origin was oxidized with different oxidizing agents (nitric acid, hydrogen peroxide, and ammonium persulfate). The microstructural properties of the starting material and the oxidized samples were characterized using sorption of nitrogen. The surface acidity was determined using Boehm titration and potentiometric titration. The changes in the surface chemistry were also studied by diffuse reflectance FTIR. Water adsorption isotherms were measured at three different temperatures close to ambient (relative pressure from 0.001 to 0.3). From the isotherms the heats of adsorption were calculated using a virial equation. The results indicated that the isosteric heats of water adsorption are affected by the surface heterogeneity only at low surface coverage. In all cases the limiting heat of adsorption was equal to the heat of water condensation (45 kJ/mol).

Salame, I.I.; Bandosz, T.J. [City Coll. of New York, NY (United States). Dept. of Chemistry] [City Coll. of New York, NY (United States). Dept. of Chemistry; [City Univ. of New York, NY (United States). Graduate School

1999-02-15

169

Development and demonstration of a Stirling/Rankine heat activated heat pump. Volume II. Phase II program test data. Final report  

SciTech Connect

This report presents the results of the Phase II and Phase IIIB Stirling/Rankine Heat Activated Heat Pump produce development program. In the Phase II program, a complete gas fired heat activated prototype residential heat pump system was developed and tested. Detailed test data from the Phase II program are presented in Volume II of this report. Results of the Phase II program indicated deficiencies in the performance of the free-piston Stirling engine and mismatching of the dynamic characteristics of the engine and the compressor.

Not Available

1984-04-09

170

[Effects of particle size of zero-valent iron on the reactivity of activating persulfate and kinetics for the degradation of acid orange 7].  

PubMed

This research described the heterogeneous reactions of persulfate with different particle sizes of zero-valent iron (including 1 mm-ZVI,150 ?m-ZVI,50 nm-ZVI) for degradation of acid orange 7(AO7) , and studied the kinetics and intermediate products of AO7 under these systems. The results demonstrated that these three types of ZVI were efficient in promoting the degradation of AO7, the degradation efficiencies of AO7 were 43% , 97% , and 100% within 90 min respectively, in the 1 mm-ZVI,150 ?m-ZVI and 50 nm- ZVI systems, respectively. With the results of kinetic fitting models, the pseudo first-order kinetics exhibited better fitting results in the 1 mm-ZVI,150 ?m-ZVI systems, while the second-order kinetics exhibited better fitting results in the 50 nm-ZVI system. And the different ZVI types exhibited difference on the AO7 degradation rate constant, which ranged as 50 nm-ZVI > 150 ?m-ZVI > 1 mm-ZVI. The iron corrosion products coating on the ZVI after reaction were composed of ?-Fe2 O3 and some Fe3O4 in the 1 mm-ZVI system while that consisted of Fe3O4 and ?-Fe2O3, FeOOH respectively, in thel50 ?m-ZVI and 50 nm-ZVI systems,. Which were identified by scanning electron microscope (SEM) with energy dispersive spectrometer (EDS) and Raman spectroscopy. Some intermediate products, including 2-naphthalenol, 2-methylphenol, 4-ethyl- 3-methyl-phenol, isoindole- 1,3-dione and phthalic acid et al. were identified by GC/MS measurement. Both UV-vis absorbance spectra and GC/MS determination indicated that there was difference in degradation paths of AO7 between the three systems. PMID:25518660

Li, Huan-xuan; Wan, Jin-quan; Ma, Yong-wen; Huang, Ming-zhiz; Wang, Yan; Chen Yang, Mei

2014-09-01

171

Heat-activated thermosensitive liposomal cisplatin (HTLC) results in effective growth delay of cervical carcinoma in mice.  

PubMed

Cisplatin (CDDP) has been identified as the primary chemotherapeutic agent for the treatment of cervical cancer, but dose limiting toxicity is a key issue associated with its clinical application. A suite of liposome formulations of CDDP has been developed in efforts to reduce systemic toxicity, but their therapeutic advantage over the free drug has been modest due to insufficient drug release at the tumor site. This report describes the development of a novel heat-activated thermosensitive liposome formulation containing CDDP (HTLC) designed to release approximately 90% of the loaded drug in less than 5min under mild heating conditions (42°C). Physico-chemical characteristics of HTLC were assessed in terms of gel to liquid crystalline phase transition temperature (Tm), drug loading efficiency, particle size, and stability. The pharmacokinetic profile and biodistribution of HTLC in non-tumor-bearing mice were evaluated over a 24h period. A sophisticated spatio-temporal elucidation of HTLC release in tumor-bearing mice was achieved by way of real-time monitoring using a magnetic resonance (MR) imaging protocol, wherein a custom-built laser-based conformal heat source was applied at the tumor volume to trigger the release of HTLC co-encapsulated with the MR contrast agent gadoteridol (Gd-HP-DO3A). MR thermometry (MRT) demonstrated that a relatively uniform temperature distribution was achieved in the tumor volume using the external laser-based heating setup. In mice bearing subcutaneously-implanted ME-180 cervical tumors, the combination of HTLC and heat resulted in a 2-fold increase in tumor drug levels at 1h post-administration compared to HTLC without heating. Furthermore, the overall tumor accumulation levels for the HTLC groups (with and without heat) at 1h post-injection were significantly higher than the corresponding free CDDP group. This translated into a significant improvement in therapeutic efficacy evaluated as tumor growth delay (p<0.05) for the heated HTLC treatment group compared to the unheated HTLC, heated or unheated free CDDP, and saline groups. Overall, findings from this study demonstrate that a heat-activated, triggered release formulation of CDDP results in a significant enhancement in the therapeutic index of this drug. PMID:24440663

Dou, Yannan N; Zheng, Jinzi; Foltz, Warren D; Weersink, Robert; Chaudary, Naz; Jaffray, David A; Allen, Christine

2014-03-28

172

Catalytic-Oxidative Leaching of Low-Grade Complex Zinc Ore by Cu (II) Ions Produced from Copper Ore in Ammonia-Ammonium Sulfate Solution  

NASA Astrophysics Data System (ADS)

The catalytic-oxidative leaching of a mixed ore, which consists of low-grade oxide copper ore and oxide zinc ore containing ZnS, was investigated in ammonia-ammonium sulfate solution. The effect of the main parameters, such as mass ratio of copper ore to zinc ore, liquid-to-solid ratio, concentration of lixivant, leaching time, and temperature, was studied. The optimal leaching conditions with a maximum extraction of Cu 92.6 pct and Zn 85.5 pct were determined as follows: the mass ratio of copper ore to zinc ore 4/10 g/g, temperature 323.15 K (50 °C), leaching time 6 hours, stirring speed 500 r/min, liquid-to-solid ratio 3.6/1 cm3/g, concentration of lixivant including ammonia 2.0 mol/dm3, ammonium sulfate 1.0 mol/dm3, and ammonium persulfate 0.3 mol/dm3. It was found that ZnS in the oxide zinc ore could be extracted with Cu(II) ion, which was produced from copper ore and was used as the catalyst in the presence of ammonium persulfate.

Liu, Zhi Xiong; Yin, Zhou Lan; Hu, Hui Ping; Chen, Qi Yuan

2012-10-01

173

Insulated heat activated ventilator  

SciTech Connect

A building construction is described comprising a building structure and a ventilator, the ventilator including a stack defining a passage having an inlet and an outlet communicating with one another, a closure operative to normally seal the passage, insulating material supported by the closure and providing an air seal within the passage under normal conditions, and normally inoperative vent actuating means associated with the closure, the vent actuating means being operative in response to the presence of combustion products for disabling the closure, the closure and the insulating material being automatically released from the passage of the stack upon disablement of the closure whereby the combustion products are exhausted through the passage of the stack to atmosphere.

Kelly, T.L.

1993-05-25

174

Reduction of persulfate ion by carbon monoxide in alkaline medium: the effect of stoichiometric and astoichiometric components on the reaction Kinetics  

SciTech Connect

The effect of the concentration of oxidant, cadalyst, and various ligands on the kinetics of the oxidation of CO have been studied kinetically, potentiometrically, and spectrometrically, and a general mechanism for the process is proposed.

Abilov, M.T.; Golodov, V.A.

1986-06-01

175

IL1beta potentiates heat-activated currents in rat sensory neurons: involvement of IL1RI, tyrosine kinase, and protein kinase C  

Microsoft Academic Search

Interleukin 1 (IL-1) is a proinflamma- tory cytokine that maintains thermal hyperalgesia and facilitates the release of calcitonin gene-related peptide from rat cutaneous nociceptors in vivo and in vitro. Brief applications of IL-1 to nociceptive neurons yielded a potentiation of heat-activated inward currents (Iheat) and a shift of activation threshold toward lower temperature without altering intracellular calcium lev- els. The

OTILIA OBREJA; PARVINDER K. RATHEE; KATHRIN S. LIPS; CARSTEN DISTLER; MICHAELA KRESS

2002-01-01

176

Ordered mesoporous cobalt oxide as highly efficient oxygen evolution catalyst.  

PubMed

Oxygen evolution from water by use of earth-abundant element-based catalysts is crucial for mass solar fuel production. In this report, a mesoporous cobalt oxide with an ultrahigh surface area (up to 250 m(2)·g(-1)) has been fabricated through Mg substitution in the mesoporous Co3O4 spinel, followed by a Mg-selective leaching process. Approximately a third of Mg cations were removed in the leaching process, resulting in a highly porous cobalt oxide with a significant amount of defects in the spinel structure. The activated mesoporous cobalt oxide exhibited high oxygen evolution activities in both the visible-light-driven [Ru(bpy)3](2+)-persulfate system and the Ce(4+)/Ce(3+) chemical water oxidation system. Under a strong acidic environment, a high turnover frequency (TOF) of ~2.2 × 10(-3) s(-1) per Co atom was achieved, which is more than twice the TOF of traditional hard-templated, mesoporous Co3O4. PMID:23448405

Rosen, Jonathan; Hutchings, Gregory S; Jiao, Feng

2013-03-20

177

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

178

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

SciTech Connect

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

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

1985-09-30

179

Recovery of microbial diversity and activity during bioremediation following chemical oxidation of diesel contaminated soils.  

PubMed

To improve the coupling of in situ chemical oxidation and in situ bioremediation, a systematic analysis was performed of the effect of chemical oxidation with Fenton's reagent, modified Fenton's reagent, permanganate, or persulfate, on microbial diversity and activity during 8 weeks of incubation in two diesel-contaminated soils (peat and fill). Chemical oxidant and soil type affected the microbial community diversity and biodegradation activity; however, this was only observed following treatment with Fenton's reagent and modified Fenton's reagent, and in the biotic control without oxidation. Differences in the highest overall removal efficiencies of 69 % for peat (biotic control) and 59 % for fill (Fenton's reagent) were partially explained by changes in contaminant soil properties upon oxidation. Molecular analysis of 16S rRNA and alkane monooxygenase (alkB) gene abundances indicated that oxidation with Fenton's reagent and modified Fenton's reagent negatively affected microbial abundance. However, regeneration occurred, and final relative alkB abundances were 1-2 orders of magnitude higher in chemically treated microcosms than in the biotic control. 16S rRNA gene fragment fingerprinting with DGGE and prominent band sequencing illuminated microbial community composition and diversity differences between treatments and identified a variety of phylotypes within Alpha-, Beta-, and Gammaproteobacteria. Understanding microbial community dynamics during coupled chemical oxidation and bioremediation is integral to improved biphasic field application. PMID:24092007

Sutton, Nora B; Langenhoff, Alette A M; Lasso, Daniel Hidalgo; van der Zaan, Bas; van Gaans, Pauline; Maphosa, Farai; Smidt, Hauke; Grotenhuis, Tim; Rijnaarts, Huub H M

2014-03-01

180

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

SciTech Connect

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

Frei, Heinz; Han, Hongxian; Frei, Heinz

2008-06-03

181

Miniaturized dielectric barrier discharge carbon atomic emission spectrometry with online microwave-assisted oxidation for determination of total organic carbon.  

PubMed

A simple, rapid, and portable system consisted of a laboratory-built miniaturized dielectric barrier discharge atomic emission spectrometer and a microwave-assisted persulfate oxidation reactor was developed for sensitive flow injection analysis or continuous monitoring of total organic carbon (TOC) in environmental water samples. The standard/sample solution together with persulfate was pumped to the reactor to convert organic compounds to CO2, which was separated from liquid phase and transported to the spectrometer for detection of the elemental specific carbon atomic emission at 193.0 nm. The experimental parameters were systematically investigated. A limit of detection of 0.01 mg L(-1) (as C) was obtained based on a 10 mL sample injection volume, and the precision was better than 6.5% (relative standard deviation, RSD) at 0.1 mg L(-1). The system was successfully applied for TOC analysis of real environmental water samples. The obtained TOC value of 30 test samples agreed well with those by the standard high-temperature combustion coupled nondispersive infrared absorption method. Most importantly, the system showed good capability of in situ continuous monitoring of total organic carbon in environmental water. PMID:24862626

Han, Bingjun; Jiang, Xiaoming; Hou, Xiandeng; Zheng, Chengbin

2014-07-01

182

Metalloporphyrin-sensitized photooxidation of water to oxygen on the surface of colloidal iridium oxides. Photochemical and pulse radiolytic studies  

SciTech Connect

Derivatives of TSPP (tetrakis(4-sulfonatophenyl)porphyrin) were prepared and tested as photosensitizers for oxidation of water to oxygen on the surface of colloidal iridium oxide. Triplet quantum yields, energies, and lifetimes were measured by laser flash photolysis. Rate constants for quenching the porphyrin triplet state with O{sub 2} and with persulfate ions were also determined. The rates of interaction between the porphyrin radical cations and colloidal IrO{sub x} particles were measured by pulse radiolysis for several of the compounds. The one-electron oxidation potentials of the porphyrins, measured by cyclic voltammetry, were varied between 0.7 and 1.4 V vs. NHE by using different metal centers and by substitution on the phenyl rings. Illumination of a porphyrin in the presence of sodium persulfate and an IrO{sub x} colloid resulted in generation of O{sub 2} in a process that was strongly dependent upon pH and upon the nature of the photosensitizer in the same manner as the kinetics determined by pulse radiolysis. The rate of O{sub 2} production under any conditions could be explained on the basis of thermodynamic criteria relating to either of the individual quenching or water oxidation steps. Zn porphyrins (0.9 < E{sub {1/2}} < 1.02 V) effected O{sub 2} production only in alkaline solution, whereas PdTSPP (E{sub {1/2}} = 1.1 V) gave efficient O{sub 2} evolution even in neutral solution. Further increase in E{sub 1/2}, as achieved with InTSPP (E{sub {1/2}} = 1.16 V), lowers the threshold pH for O{sub 2} evolution, and pulse radiolysis experiments confirmed that the radical cation of this porphyrin is the most reactive toward the catalyst, reacting at diffusion-controlled rates even in acidic solutions. However, the rate of O{sub 2} formation with InTSPP was very low due to the inefficient photochemistry arising from the incomplete quenching of this less-reducing porphyrin triplet state by persulfate ions.

Nahor, G.S.; Neta, P. (National Institute of Standards and Technology, Gaithersburg, MD (USA)); Hambright, P. (Howard Univ., Washington, DC (USA)); Thompson, A.N. Jr. (Spelman College, Atlanta, GA (USA)); Harriman, A. (Univ. of Texas, Austin (USA))

1989-08-10

183

Solid-liquid separation of oxidized americium from fission product lanthanides  

NASA Astrophysics Data System (ADS)

The separation of americium from the lanthanides and curium is a requirement if transmutation of americium is to be performed in advanced nuclear fuel cycles. Oxidation of Am3+ to AmO2+ or AmO22+ may allow separation of Am from Ln and Cm in one step, since the lanthanides and curium do not have higher oxidation states as accessible. Two possible solid-liquid separation methods have been developed to address this difficult separation. Under acidic conditions using oxone or persulfate, the oxidation and retention of tracer Am in the aqueous phase has been observed with a separation factor of 11 ± 1. Most of these studies have been conducted using 237NpO2(NO3), 233UO2(NO3)2, 238Pu(NO3)4 and 241Am(NO3)3 at radiotracer concentrations. Lanthanides precipitate as the sodium or potassium europium double sulfate salt. Under basic conditions, ozone oxidation of Am(CO3)OH(s) solubilizes Am from a lanthanide carbonate hydroxide solid phase to the aqueous phase as the AmO2(CO3)34-or AmO2(CO3)35- species. For the ozone oxidation of the americium tracer a separation factor of 1.6 ± 0.8 and 47 ± 2 for the oxidation/separation in Na2CO3 and NaHCO3 respectively.

Shehee, T. C.; Martin, L. R.; Nash, K. L.

2010-03-01

184

An exceptionally fast homogeneous carbon-free cobalt-based water oxidation catalyst.  

PubMed

An all-inorganic, oxidatively and thermally stable, homogeneous water oxidation catalyst based on redox-active (vanadate(V)-centered) polyoxometalate ligands, Na10[Co4(H2O)2(VW9O34)2]·35H2O (Na101-V2, sodium salt of the polyanion 1-V2), was synthesized, thoroughly characterized and shown to catalyze water oxidation in dark and visible-light-driven conditions. This synthetic catalyst is exceptionally fast under mild conditions (TOF > 1 × 10(3) s(-1)). Under light-driven conditions using [Ru(bpy)3](2+) as a photosensitizer and persulfate as a sacrificial electron acceptor, 1-V2 exhibits higher selectivity for water oxidation versus bpy ligand oxidation, the final O2 yield by 1-V2 is twice as high as that of using [Co4(H2O)2(PW9O34)2](10-) (1-P2), and the quantum efficiency of O2 formation at 6.0 ?M 1-V2 reaches ?68%. Multiple experimental results (e.g., UV-vis absorption, FT-IR, (51)V NMR, dynamic light scattering, tetra-n-heptylammonium nitrate-toluene extraction, effect of pH, buffer, and buffer concentration, etc.) confirm that the polyanion unit (1-V2) itself is the dominant active catalyst and not Co(2+)(aq) or cobalt oxide. PMID:24937166

Lv, Hongjin; Song, Jie; Geletii, Yurii V; Vickers, James W; Sumliner, Jordan M; Musaev, Djamaladdin G; Kögerler, Paul; Zhuk, Petro F; Bacsa, John; Zhu, Guibo; Hill, Craig L

2014-07-01

185

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

186

Destruction of cyanobacterial toxin cylindrospermopsin by hydroxyl radicals and sulfate radicals using UV-254 nm activation of hydrogen peroxide, persulfate and peroxymonosulfate  

EPA Science Inventory

Abstract: With increasing worldwide incidence of toxic cyanobacterial blooms in bodies of water, cylindrospermopsin (CYN) has become a significant concern to public health and water management officials. In this study, the removal of CYN by UV-254 nm-mediated advanced oxidation ...

187

Component analysis of dyads designed for light-driven water oxidation.  

PubMed

A series of seven dyad molecules have been prepared utilizing a [Ru(tpy)(NN)I](+) type oxidation catalyst (NN = 2,5-di(pyrid-2'-yl) pyrazine (1), 2,5-di-(1',8'-dinaphthyrid-2'-yl) pyrazine (2), or 4,6-di-(1',8'-dinaphthyrid-2'-yl) pyrimidine (3). The other bidentate site of the bridging ligand was coordinated with 2,2'-bipyridine (bpy), 1,10-phenanthroline (phen), or a substituted derivative. These dinuclear complexes were characterized by their (1)H NMR spectra paying special attention to protons held in the vicinity of the electronegative iodide. In one case, 10a, the complex was also analyzed by single crystal X-ray analysis. The electronic absorption spectra of all the complexes were measured and reported as well as emission properties for the sensitizers. Oxidation and reduction potentials were measured and excited state redox properties were calculated from this data. Turnover numbers, initial rates, and induction periods for oxygen production in the presence of a blue LED light and sodium persulfate as a sacrificial oxidant were measured. Similar experiments were run without irradiation. Dyad performance correlated well with the difference between the excited state reduction potential of the photosensitizer and the ground state oxidation potential of the water oxidation dyad. The most active system was one having 5,6-dibromophen as the auxiliary ligand, and the least active system was the one having 4,4'-dimethylbpy as the auxiliary ligand. PMID:24364791

Kohler, Lars; Kaveevivitchai, Nattawut; Zong, Ruifa; Thummel, Randolph P

2014-01-21

188

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

PubMed Central

Aim: This study aimed at investigating the effect of adding 5% to 20% by weight aluminium oxide powder (Al2O3) on thermal diffusivity of heat–polymerized acrylic resin. Material and Methods: Twenty five cylindrical test specimens with an embedded thermocouple were used to determine thermal diffusivity over a physiologic temperature range (0 to 70°C). The specimens were divided into five groups (5 specimens/group) which were coded A to E. Group A was the control group (unmodified acrylic resin specimens). The specimens of the remaining four groups were reinforced with 5%, 10%, 15%, and 20% Al2O3 by weight. Results were analysed by using one–way analysis of variance (ANOVA). Results: Test specimens which belonged to Group E showed the highest mean thermal diffusivity value of 10.7mm2/sec, followed by D (9.09mm2/sec), C (8.49mm2/sec), B(8.28mm2/sec) and A(6.48mm2/sec) groups respectively. Thermal diffusivities of the reinforced acrylic resins were found to be significantly higher than that of the unmodified acrylic resin. Thermal diffusivity was found to increase in proportion to the weight percentage of alumina filler. Conclusion: Al2O3 fillers have potential to provide increased thermal diffusivity. Increasing the heat transfer characteristics of the acrylic resin base material could lead to more patient satisfaction. PMID:24086917

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

2013-01-01

189

Ciprofloxacin oxidation by UV-C activated peroxymonosulfate in wastewater.  

PubMed

This work aimed at demonstrating the advantages to use sulfate radical anion for eliminating ciprofloxacin residues from treated domestic wastewater by comparing three UV-254nm based advanced oxidation processes: UV/persulfate (PDS), UV/peroxymonosulfate (PMS) and UV/H2O2. In distilled water, the order of efficiency was UV/PDS>UV/PMS>UV/H2O2 while in wastewater, the most efficient process was UV/PMS followed by UV/PDS and UV/H2O2 mainly because PMS decomposition into sulfate radical anion was activated by bicarbonate ions. CIP was fully degraded in wastewater at pH 7 in 60min for a [PMS]/[CIP] molar ratio of 20. Nine transformation products were identified by liquid chromatography-high resolution-mass spectrometry allowing for the establishment of degradation pathways in the UV/PMS system. Sulfate radical anion attacks prompted transformations at the piperazinyl ring through a one electron oxidation mechanism as a major pathway while hydroxyl radical attacks were mainly responsible for quinolone moiety transformations as a minor pathway. Sulfate radical anion generation has made UV/PMS a kinetically effective process in removing ciprofloxacin from wastewater with the elimination of ciprofloxacin antibacterial activity. PMID:24333713

Mahdi-Ahmed, Moussa; Chiron, Serge

2014-01-30

190

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory : determination of nonpurgeable suspended organic carbon by wet-chemical oxidation and infrared spectrometry  

USGS Publications Warehouse

Precision and accuracy results are described for the determination of nonpurgeable suspended organic carbon (SOC) by silver-filter filtration, wet-chemical oxidation, and infrared determination of hte resulting carbon dioxide (CO2) used at the U.S. Geological Survey's nationalWater Quality Laboratory. An aliquot of raw water isfiltered through a 0.45-micrometer silver filter. The trapped organic material is oxidized using phosphoric acid and potassium persulfate in a scaled glass ampule,and the rseulting CO2 is measured by an infrared CO2 detector. The amount of CO3 is proportional to the concentration of chemically oxidizable nonpurgeable organic carbon in the sample. The SOC method detection limit for routine analysis is 0.2 milligram per liter. The average percent recovery is 97.1 percent and the average standard deviation is 11 percent.

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

1997-01-01

191

Fenton-like oxidation of 2,4,6-trinitrotoluene using different iron minerals.  

PubMed

Degradation of 2,4,6-trinitrotoluene (TNT) was investigated in presence of different oxidants (Fenton's reagent, sodium persulfate, peroxymonosulfate and potassium permanganate) and different iron minerals (ferrihydrite, hematite, goethite, lepidocrocite, magnetite and pyrite) either in aqueous solution or in soil slurry systems. Fenton's reagent was the only oxidant able to degrade TNT in solution (k(app)=0.0348 min(-1)). When using iron oxide as heterogeneous catalyst at pH 3, specific reaction rate constants per surface area were k(surf)=1.47.10(-3) L min(-1) m(-2) and k(surf)=0.177 L min(-1) m(-2) for magnetite and pyrite, respectively while ferric iron minerals were inefficient for TNT degradation. The major asset of iron mineral catalyzed Fenton-like treatment has been the complete oxidation of the pollutant avoiding the accumulation of possible toxic by-products. In soil slurry systems, 38% abatement of the initial TNT concentration (2 g/kg) was reached after 24 h treatment time at neutral pH. Rate limiting steps were the availability of soluble iron at neutral pH together with desorption of the TNT fraction sorbed on the clay mineral surfaces. PMID:17662375

Matta, Roger; Hanna, Khalil; Chiron, Serge

2007-10-15

192

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

193

Magnesium Oxide  

MedlinePLUS

Magnesium is an element your body needs to function normally. Magnesium oxide may be used for different reasons. Some ... to relieve heartburn, sour stomach, or acid indigestion. Magnesium oxide also may be used as a laxative ...

194

PEGylated liposomes with NGR ligand and heat-activable cell-penetrating peptide-doxorubicin conjugate for tumor-specific therapy.  

PubMed

Cell-penetrating peptides (CPPs) mediated tumor-oriented nanocarriers have been widely studied by researchers recently. However, applications of CPPs in vivo were usually hampered by their loss in untargeted tissues and enzymatic degradation. These shortfalls required strategies to camouflage CPPs before their arrival at the targeted site. In this work, we constructed a thermosensitive liposome (TSL) containing Asparagines-Glycine-Arginine (NGR) peptide as the targeting moiety and heat-activable cell-penetrating peptide-doxorubicin conjugate for enhancing specific cancer therapy. Different to the masking strategies of CPPs reported, CPPs existing in conjugation form of CPPs and doxorubicin (CPP-Dox) were hidden in TSL to cloak and protect CPPs. Meanwhile, NGR moiety and local tumor hyperthermia were utilized to achieve specific targeting of CPPs to the tumor. The nanocarrier (CPP-Dox/NGR-TSL) prepared in this work possessed suitable physiochemical properties such as small particle size of about 90 nm, high drug encapsulation efficiency of approximately 95%, good stability in the medium containing 10% fetal bovine serum (FBS) and so on. In vitro experiments on Human fibrosarcoma cells (HT-1080) and human breast adenocarcinoma cells (MCF-7) verified the specific targeting ability and enhanced intracellular drug delivery of the liposomes to HT-1080 cells. Furthermore, comparing with NGR-targeted TSL containing Dox (Dox/NGR-TSL), the results of intravenous administration showed CPP-Dox/NGR-TSL significantly inhibited tumor growth in nude mice xenografted HT-1080 tumors and excellent body safety. In conclusion, the nanocarrier constructed in this study would be a safe and efficiently drug delivery system for specific cancer treatment. PMID:24565519

Yang, Yanfang; Yang, Yang; Xie, Xiangyang; Cai, Xingshi; Zhang, Hui; Gong, Wei; Wang, Zhiyuan; Mei, Xingguo

2014-05-01

195

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

196

Oxide Spintronics  

Microsoft Academic Search

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

Manuel Bibes; Agns Barthelemy

2007-01-01

197

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

198

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

199

Quantitation of carbon in oil shale process wastewaters: coulometry coupled with ultraviolet-peroxydisulfate and high-temperature oxidation  

SciTech Connect

Wastewaters from the production of synfuels, in particular oil shale retort waters, present several major problems to various instrument configurations designed for carbon analysis. A carbon analyzer was fabricated from commercially available oxidation and detection units. Carbon oxidation occurred in an ultraviolet (UV) photochemical reactor using acid peroxydisulfate; quantitation of the evolved carbon dioxide was accomplished with an automatic coulometric titrator. This new design eliminated the problems of (1) instrument downtime caused by fouling of high-temperature combustion catalysts and corrosion of furnace combustion tubes, (2) limited linear dynamic range and upper detection limit (namely, infrared detection), and (3) frequent detector calibration (namely, infrared and flame ionization detection). The UV-persulfate/coulometric titration carbon analyzer was compared statistically with a high-temperature combustion system that is suitable for use with an ASTM method on the basis of (1) the accuracy and precision of recovery of total dissolved carbon (TDC) and dissolved organic carbon (DOC) for nitrogen heterocycles, which were of primary interest because of their preponderance in oil shale process waters and their reported resistance to certain oxidation methods, and (2) the precision of TDC and DOC determinations for nine oil shale process wastewaters. Several qualitative considerations are discussed for both analyzers, including ease of operation, instrument downtime, and maintenance costs. 35 references, 7 figures, 5 tables.

Langlois, G.W.; Jones, B.M.; Sakaji, R.H.; Daughton, C.G.

1984-07-01

200

TRPV3 regulates nitric oxide synthase-independent nitric oxide synthesis in the skin.  

PubMed

Nitric oxide (NO) is an unstable signalling molecule synthesized de novo mainly from L-arginine by NO synthase (NOS) enzymes. Nitrite reduction can also produce NO, predominantly within body fluids (for example, saliva, sweat and blood plasma) and under extreme hypoxic and acidic conditions. It remains unknown if intracellular canonical signalling pathways regulate nitrite-dependent NO production. Here we examine NO production in the skin, a hypoxic tissue enriched in nitrites wherein NO has important roles in wound healing and other biological processes. We show that activation of TRPV3, a heat-activated transient receptor potential ion channel expressed in keratinocytes, induces NO production via a nitrite-dependent pathway. TRPV3 and nitrite are involved in keratinocyte migration in vitro and in wound healing and thermosensory behaviours in vivo. Our study demonstrates that activation of an ion channel can induce NOS-independent NO production in keratinocytes. PMID:21712817

Miyamoto, Takashi; Petrus, Matt J; Dubin, Adrienne E; Patapoutian, Ardem

2011-01-01

201

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

202

Identification and cleavage of breakable single bonds by selective oxidation, reduction, and hydrolysis. Annual report, October 1, 1980-September 30, 1981  

SciTech Connect

The objective of this project is to determine the structure of bituminous coal by determining the proportions of the various kinds of connecting bonds and how they can best be broken. Results obtained during the past quarter are presented for the following tasks: (1) extractions and fractionations of coal products which covers pyridine extraction, fractionation of TIPS fractions, EDA extraction of Illinois No. 6 coal and swelling ratios of coal samples; (2) experiments on breakable single bonds which cover reactions of ethylenediamine and model ethers, reaction of pyridine-extracted coal with Me/sub 3/SiI, Baeyer-Villiger oxidations, reaction to diphenylmethane with 15% HNO/sub 3/, cleavage of TIPS with ZnI/sub 2/, and cleavage of black acids; and (3) oxygen oxidation No. 18. Some of the highlights of these studies are: (1) some model ethers are not cleaved by EDA under extraction conditions; (2) oxidation of diaryl ketones with m-chloroperbenzoic acid and saponification of the resulting esters in promising for identifying ketones, (3) treatment of a black acid with pyridine hydroiodide reduced the acid's molecular weight and increased its solubility in pyridine, but treatment with ZnI/sub 2/ was ineffective; (4) in comparison with 0.1 M K/sub 2/S/sub 2/O/sub 8/, 0.01 M persulfate is relatively ineffective in accelerating oxidation of BnNH/sub 2/-extracted coal in water suspension. 2 figures, 3 tables.

Hirschon, A.S.; Zevely, J.; Mayo, F.R.

1981-11-12

203

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

PubMed

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

Díaz, Sergio Cueto; Encinar, Jorge Ruiz; Sanz-Medel, Alfredo; Alonso, J Ignacio García

2013-02-01

204

Design, synthesis, and characterization of materials for controlled line deposition, environmental remediation, and doping of porous manganese oxide material  

NASA Astrophysics Data System (ADS)

This thesis covers three topics: (1) coatings formed from sol-gel phases, (2) environmental remediation, and (3) doping of a porous manganese oxide. Synthesis, characterization, and application were investigated for each topic. Line-formations were formed spontaneously by self-assembly from vanadium sol-gels and other metal containing solutions on glass substrates. The solutions were prepared by the dissolution of metal oxide or salt in water. A more straightforward method is proposed than used in previous work. Analyses using optical microscopy, atomic force microscopy, scanning electron microscopy, energy-dispersive X-ray analysis, and infrared spectroscopy showed discreet lines whose deposition could be controlled by varying the concentration. A mechanism was developed from the observed results. Microwave heating, the addition of graphite rods, and oxidants, can enhance HCB remediation from soil. To achieve remediation, a TeflonRTM vessel open to the atmosphere along with an oxidant, potassium persulfate (PerS) or potassium hydroxide, along with uncoated or aluminum oxide coated, graphite rods were heated in a research grade microwave oven. Microwave heating was used to decrease the heating time, and graphite rods were used to increase the absorption of the microwave energy by providing thermal centers. The results showed that the percent HCB removed was increased by adding graphite rods and oxidants. Tungsten, silver, and sulfur were investigated as doping agents for K--OMS-2. The synthesis of these materials was carried out with a reflux method. The doping of K--OMS-2 led to changes in the properties of a tungsten doped K--OMS-2 had an increased resistivity, the silver doped material showed improved epoxidation of trans-stilbene, and the addition of sulfur produced a paper-like material. Rietveld refinement of the tungsten doped K--OMS-2 showed that the tungsten was doped into the framework.

Calvert, Craig A.

205

Treating organic pollutants in urban runoff using slow-release oxidants and storm pipes: A field investigation  

NASA Astrophysics Data System (ADS)

Non-point source (NPS) contamination is a major concern for urban aquatic environments. This study tested the efficacy of using slow-release oxidants emplaced in storm pipes for treating organic pollutants in urban storm runoff through proof-of-concept laboratory tests and a field demonstration test in Athens, OH. Release rates of slow-release persulfate (SR-PS), slow-release hydrogen pyroxide (SR-HP), and slow-release iron (SR-Fe) were estimated through column tests. Runoff samples were collected at a storm pipe discharge point in the study area for 3 storm events having different prior drought periods to establish baseline concentrations of organic pollutants. Samples were analyzed for Methyl-tert-butyl-ether (MTBE), Naphthalene, and total organic carbon contents. The proof-of-concept flow-through test demonstrated that up 90% of pollutants can be removed by the SR-PS/Fe within 20 minutes of reaction time. The SR-PS/HP/Fe forms are emplaced in several storm drains where the pollutants would have ~15 minutes of reaction with the oxidants released from the slow-release forms. Preliminary results suggest that the SR-PS/HP/Fe forms installed in the storm pipes can reduce NPS pollutants in the urban storm runoff in a sustainable manner.

Eyerdom, T. J.; Lee, E.; Kim, Y.

2013-12-01

206

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

USGS Publications Warehouse

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

Burkhardt, M.R.; Brenton, R.W.; Kammer, J.A.; Jha, V.K.; O'Mara-Lopez, P. G.; Woodworth, M.T.

1999-01-01

207

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

SciTech Connect

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

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

1999-07-02

208

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

209

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

210

Visible-light-induced water oxidation mediated by a mononuclear-cobalt(II)-substituted silicotungstate.  

PubMed

A mononuclear-cobalt(II)-substituted silicotungstate, K10[Co(H2O)2(?-SiW10O35)2]?23?H2O (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(H2O)2(?-SiW10O35)2](10-) (POM-2) and [Mn(H2O)2(?-SiW10O35)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(H2O)2(?-PW9O34)2](10-) (Co4-POM) and [Co(III)Co(II)(H2O)W11O39](7-) (Co2-POM)) under optimum conditions. PMID:25145473

Xiang, Rui; Ding, Yong; Zhao, Junwei

2014-11-01

211

On the adsorption/oxidation of hydrogen sulfide on activated carbons at ambient temperatures.  

PubMed

Activated carbons of various origins (bituminous coal, wood, coconut shells, and peat) were studied as adsorbents of hydrogen sulfide. Before the experiments the surface of the adsorbents was characterized by using the sorption of nitrogen, Boehm and potentiometric titrations, thermal analysis, and FTIR. The adsorbents were chosen to differ in their surface areas, pore volumes, and surface acidities. To broaden the spectrum of surface acidity, carbons were oxidized by using nitric acid and ammonium persulfate. After hydrogen sulfide adsorption the species present on the surface were analyzed using thermal analysis, ion chromatography, and elemental analysis. The H(2)S breakthrough capacity tests showed that the performances of different carbons differ significantly. For a good performance of carbons as hydrogen sulfide adsorbents a proper combination of surface chemistry of carbon and porosity is needed. It was demonstrated that a more acidic environment promotes the formation of sulfur oxides and sulfuric acid despite yielding small H(2)S removal capacities. On the other hand, a basic environment favors the formation of elemental sulfur (sulfur radicals) and yields high capacities. The presence of a sufficient amount of water preadsorbed on the carbon surface to facilitate dissociation also plays an important role in the process of H(2)S adsorption/oxidation. The results showed that there is a critical value in carbon surface acidity, which when exceeded results in a negligible hydrogen sulfide breakthrough capacity. This is consistent with the mechanism of H(2)S adsorption on unmodified carbons, where the rate-limiting step is the reaction of adsorbed hydrogen sulfide ion with dissociatively adsorbed oxygen. When the acidity is expressed as pH, its value should be higher than 5 to ensure the effective removal of hydrogen sulfide from the gas phase. Study of carbon regeneration using water washing and heat treatment showed that the adsorbents can be regenerated to about 40% of their initial capacity. PMID:16290378

Bandosz, Teresa J

2002-02-01

212

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...

213

Use of Advanced Oxidation and Aerobic Degradation for Remediation of Various Hydrocarbon Contaminates  

SciTech Connect

Western Research Institute in conjunction with Sierra West Consultants, Inc., Tetra Tech, Inc., and the U.S. Department of Energy conducted laboratory and field studies to test different approaches to enhance degradation of hydrocarbons and associated contaminants. WRI in conjunction with Sierra West Consultants, Inc., conducted a laboratory and field study for using ozone to treat a site contaminated with MTBE and other hydrocarbons. Results from this study demonstrate that a TOD test can be used to resolve the O{sub 3} dosage problem by establishing a site-specific benchmark dosage for field ozone applications. The follow-up testing of the laboratory samples provided indications that intrinsic biodegradation could be stimulated by adding oxygen. Laboratory studies also suggests that O3 dosage in the full-scale field implementation could be dialed lower than stoichiometrically designed to eliminate the formation of Cr(VI). WRI conducted a study involving a series of different ISCO oxidant applications to diesel-contaminated soil and determined the effects on enhancing biodegradation to degrade the residual hydrocarbons. Soils treated with permanganate followed by nutrients and with persulfate followed by nutrients resulted in the largest decrease in TPH. The possible intermediates and conditions formed from NOM and TPH oxidation by permanganate and activated persulfate favors microbial TPH degrading activity. A 'passive-oxidation' method using microbial fuel cell (MFC) technology was conducted by WRI in conjunction with Tetra Tech, Inc., to degrade MTBE in groundwater. These experiments have demonstrated that a working MFC (i.e., one generating power) could be established in the laboratory using contaminated site water or buffered media inoculated with site water and spiked with MTBE, benzene, or toluene. Electrochemical methods were studied by WRI with goal of utilizing low voltage and amperage electrical sources for 'geo-oxidation' of organic contaminants. The results from a study with TCE contaminated-clay indicate that electrochemically inducing reductive dechlorination of TCE in a saturated matrix may offer an effective and viable alternative to remediation TCE and other contaminants with potential of being reduced. Another study focused on steel wool oxidation to electrochemically increase population of hydrocarbon-degrading denitrifying bacteria. Significantly larger denitrifying activity was observed in the cathode chamber of a treatment unit setup like an MFC with steel wool as the anode. This enhanced nitrate reduction could be due to direct electron utilization by denitrifying bacteria on the cathode, thereby stimulating microbial denitrification or a combination of electron transfer directly to NO{sub 3}{sup -} and electron transfer to nitrate reducing bacteria, which may serve as a type of bio-catalyst on the cathode for nitrate reduction. Overall, the studies conducted under Task 72 demonstrated different innovative methods to enhance petroleum hydrocarbon degradation and associated contaminants.

Paul Fallgren

2009-03-06

214

Oxide surfaces.  

PubMed

Although the history of metal oxides and their surfaces goes back several decades to landmark studies, such as Mott and Peierls' explanation of electrical insulation in materials that are predicted in band theory to be conducting, or the observation by Morin of the superfast metal-to-insulator transition in vanadium dioxide, it is only in the last two decades that the world of condensed matter physics has become increasingly dominated by research into complex metal oxides. This has been driven most notably by an attempt to better understand and describe the fundamental physical processes behind their seemingly endless spectrum of properties, which in turn has also led to the discovery of novel phenomena, most prominently demonstrated by the discovery of high-temperature superconductivity in 1986, colossal magnetoresistance in 1994, and most recently, the formation of a two-dimensional conducting layer at the interface between two band insulators in 2004. One important reason why metal oxides, particularly in the form of thin films, have become such a popular subject for basic condensed matter research is that they offer a uniquely versatile materials base for the development of novel technologies. They owe this versatility both to the many different elemental combinations that lead to structurally similar forms, and also to the fact that in many cases, the strong interaction between the valence electrons means that there is a subtle interplay between structure and magnetic and electronic properties. This aspect has led in recent years to the birth or renaissance of research fields such as spintronics, orbital ordering, and multiferroics. Surfaces and interfaces are especially interesting in these strongly-correlated electron systems, where the rearrangement of electrical charge resulting from a minimization of surface or interfacial energy can have unexpected and often exciting consequences. Indeed, as the drive to miniaturize devices well below the micron size continues, the fraction of material constituting `non-bulklike' properties is becoming increasingly significant. On the other hand, the degree of sophistication needed to understand and predict these complex systems has driven a complementary thrust in theoretical modelling, beginning as long ago as 1963, with Hubbard's addition to the tight-binding model of the formulation of conduction in terms of a hopping integral. The present level of understanding is now so advanced that theory and experiment are no longer so distinct, both gaining further insights from one another. The aim of this special issue in the Journal of Physics: Condensed Matter is to convey to the reader the most up-to-date understanding of the physics of the surfaces, interfaces, and thin films of complex metal oxides, in a clear and accessible manner. The order of the 16 contributions reflects the broad range of disciplines within this field, beginning with general considerations and theoretical models, continuing with film growth techniques and characterization, and concluding with material types and devices. It is fairly safe to assume that research in this area will enjoy as illustrious and long-lived a future as it has had a past. As such, it is hoped that this contribution will accurately reflect this status in the first decade of the 21st Century and long provide a reference for physicists continuing on this exciting Odyssey. PMID:21694334

Willmott, Phil

2008-07-01

215

Nitric oxide  

PubMed Central

Nitric oxide (NO) is a highly inducible molecule and overaccumulated during stress responses, such as drought, cold and pathogen infection. Several key developmental processes within a plant life cycle have been reported to be signaled by this gaseous molecule, and among them seed germination, de-etiolation, gravitropic response or root growth are well-characterized. The importance of NO as a plant growth and stress regulator is emerging considerably, despite the current knowledge about its signaling pathway is still limited. Therefore, the identification and characterization at the molecular level of NO targets is essential to get a deeper insight into this pathway. Here we characterize the effect of NO on root development in Arabidopsis and found that NO application reduces cell lengths in differentiation zone. Additionally, the contribution of the gibberellin (GA) signaling pathway to the NO root-related phenotypes, mainly through DELLA repressors, is also depicted. PMID:22353861

Fernández-Marcos, María; Sanz, Luis; Lorenzo, Óscar

2012-01-01

216

PREFACE: Semiconducting oxides Semiconducting oxides  

NASA Astrophysics Data System (ADS)

Semiconducting oxides are amongst the most widely studied and topical materials in contemporary condensed matter science, with interest being driven both by the fundamental challenges posed by their electronic and magnetic structures and properties, and by the wide range of applications, including those in catalysis and electronic devices. This special section aims to highlight recent developments in the physics of these materials, and to show the link between developing fundamental understanding and key application areas of oxide semiconductors. Several aspects of the physics of this wide and expanding range of materials are explored in this special section. Transparent semiconducting oxides have a growing role in several technologies, but challenges remain in understanding their electronic structure and the physics of charge carriers. A related problem concerns the nature of redox processes and the reactions which interconvert defects and charge carriers—a key issue which may limit the extent to which doping strategies may be used to alter electronic properties. The magnetic structures of the materials pose several challenges, while surface structures and properties are vital in controlling catalytic properties, including photochemical processes. The field profits from and exploits a wide range of contemporary physical techniques—both experimental and theoretical. Indeed, the interplay between experiment and computation is a key aspect of contemporary work. A number of articles describe applications of computational methods whose use, especially in modelling properties of defects in these materials, has a long and successful history. Several papers in this special section relate to work presented at a symposium within the European Materials Research Society (EMRS) meeting held in Warsaw in September 2010, and we are grateful to the EMRS for supporting this symposium. We would also like to thank the editorial staff of Journal of Physics: Condensed Matter for their help in producing this special section. We hope that it conveys some of the excitement and significance of the field. Semiconducting oxides contents Chemical bonding in copper-based transparent conducting oxides: CuMO2 (M = In, Ga, Sc) K G Godinho, B J Morgan, J P Allen, D O Scanlon and G W Watson Electrical properties of (Ba, Sr)TiO3 thin films with Pt and ITO electrodes: dielectric and rectifying behaviourShunyi Li, Cosmina Ghinea, Thorsten J M Bayer, Markus Motzko, Robert Schafranek and Andreas Klein Orientation dependent ionization potential of In2O3: a natural source for inhomogeneous barrier formation at electrode interfaces in organic electronicsMareike V Hohmann, Péter Ágoston, André Wachau, Thorsten J M Bayer, Joachim Brötz, Karsten Albe and Andreas Klein Cathodoluminescence studies of electron irradiation effects in n-type ZnOCasey Schwarz, Yuqing Lin, Max Shathkin, Elena Flitsiyan and Leonid Chernyak Resonant Raman scattering in ZnO:Mn and ZnO:Mn:Al thin films grown by RF sputteringM F Cerqueira, M I Vasilevskiy, F Oliveira, A G Rolo, T Viseu, J Ayres de Campos, E Alves and R Correia Structure and electrical properties of nanoparticulate tungsten oxide prepared by microwave plasma synthesisM Sagmeister, M Postl, U Brossmann, E J W List, A Klug, I Letofsky-Papst, D V Szabó and R Würschum Charge compensation in trivalent cation doped bulk rutile TiO2Anna Iwaszuk and Michael Nolan Deep level transient spectroscopy studies of n-type ZnO single crystals grown by different techniquesL Scheffler, Vl Kolkovsky, E V Lavrov and J Weber Microstructural and conductivity changes induced by annealing of ZnO:B thin films deposited by chemical vapour depositionC David, T Girardeau, F Paumier, D Eyidi, B Lacroix, N Papathanasiou, B P Tinkham, P Guérin and M Marteau Multi-component transparent conducting oxides: progress in materials modellingAron Walsh, Juarez L F Da Silva and Su-Huai Wei Thickness dependence of the strain, band gap and transport properties of epitaxial In2O3 thin films grown on Y-stabilised ZrO2(111) K H L Zhang, V K Lazarov, T D Veal, F

Catlow, Richard; Walsh, Aron

2011-08-01

217

Oxidation resistance of silicon ceramics  

NASA Technical Reports Server (NTRS)

Oxidation resistance, and examples of oxidation of SiC, Si3N4 and sialon are reviewed. A description is given of the oxidation mechanism, including the oxidation product, oxidation reaction and the bubble size. The oxidation reactions are represented graphically. An assessment is made of the oxidation process, and an oxidation example of silicon ceramics is given.

Yasutoshi, H.; Hirota, K.

1984-01-01

218

Modification of the surface chemistry of single- and multi-walled carbon nanotubes by HNO3 and H2SO4 hydrothermal oxidation for application in direct contact membrane distillation.  

PubMed

A specific methodology based on nitric acid hydrothermal oxidation was used to control the surface chemistry of multi-walled (MWCNTs) and single-walled (SWCNTs) carbon nanotubes (CNTs) with different lengths, and this methodology was adapted to the use of sulphuric acid containing ammonium persulfate as an oxidizing agent. The amount of oxygen-containing surface groups depends on the number and length of the graphene layers of the CNTs, thicker and shorter CNTs having more reactive sites for surface functionalization. In particular, the oxidation of MWCNTs was more pronounced than that of short SWCNTs and less surface groups were introduced into long SWCNTs, regardless of the acid used at any fixed concentration. It was also possible to tailor the surface chemistry of both SWCNTs and MWCNTs by using the adopted methodologies, and the amount of both oxygen- and sulphur-containing functional groups was correlated with the concentration of each oxidizing agent used. Mathematical functions that allow precise control of the amount and type of the surface groups introduced into carbon nanotubes were obtained. Buckypapers were also prepared over a polytetrafluoroethylene commercial membrane. These membranes were tested in direct contact membrane distillation and, under salinity conditions, the membrane prepared using oxidized MWCNTs (instead of SWCNTs) was the most efficient, the permeate flux of the commercial membrane significantly increasing in the presence of these CNTs, while completely rejecting chloride ions. In addition, the permeate flux was precisely correlated with the amount of oxygenated functional surface groups (as well as with the pH of point of zero charge) of the oxidized MWCNTs. PMID:24821484

Morales-Torres, Sergio; Silva, Tânia L S; Pastrana-Martínez, Luisa M; Brandão, Ana T S C; Figueiredo, José L; Silva, Adrián M T

2014-06-28

219

A Ru-Co hybrid material based on a molecular photosensitizer and a heterogeneous catalyst for light-driven water oxidation.  

PubMed

A novel approach to anchor a molecular photosensitizer onto a heterogeneous water oxidation catalyst via coordination bonds is presented. A photosensitizer (1) based on [Ru(bpy)3](2+) and decorated with two methylenediphosphonate (M2P) groups has been designed and synthesized for this purpose. The M2P groups in complex 1 allow for coordination of cobalt ions to afford a novel molecular-heterogeneous hybrid material P1. Scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to characterize P1 as an amorphous, non-uniform material that contains Ru and Co in a ratio of 1?:?2. A suspension of P1 in a buffered aqueous solution is active as a light-driven water oxidation catalyst in the presence of persulfate (S2O8(2-)) as electron acceptor. The yield of oxygen is higher when P1 is prepared in situ by mixing and illuminating 1 and Co(2+) in the presence of S2O8(2-). After oxygen evolution ceases, a second material P2 can be isolated from the reaction mixture. P2 is characterized by a lower Ru content than P1, and contains Co in a higher oxidation state. Interestingly, P2 as a freshly prepared suspension is also active for light-driven water oxidation. It is shown that 1 resides in the interior of P1 and P2, and is thus in a location where undesirable quenching pathways of the photo-excited state of 1 limit the oxygen production yields for both P1 and P2. PMID:24419175

Wang, Hong-Yan; Liu, Jia; Zhu, Jiefang; Styring, Stenbjörn; Ott, Sascha; Thapper, Anders

2014-02-28

220

Jeff Koebbe Nitrous Oxide  

E-print Network

Jeff Koebbe Chem 3151 Nitrous Oxide Nitrous Oxide stats: N2O is a colorless non-flammable gas to survive. denitrification depletes 3 CO2 and results in 2 N2O 1/3 of total atmospheric nitrous oxide% of human caused nitrous oxide emissions from streams and rivers Atmospheric N2O increased by 20% over

Toohey, Darin W.

221

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

222

Photo-oxidation catalysts  

SciTech Connect

Photo-oxidation catalysts and methods for cleaning a metal-based catalyst are disclosed. An exemplary catalyst system implementing a photo-oxidation catalyst may comprise a metal-based catalyst, and a photo-oxidation catalyst for cleaning the metal-based catalyst in the presence of light. The exposure to light enables the photo-oxidation catalyst to substantially oxidize absorbed contaminants and reduce accumulation of the contaminants on the metal-based catalyst. Applications are also disclosed.

Pitts, J. Roland (Lakewood, CO); Liu, Ping (Irvine, CA); Smith, R. Davis (Golden, CO)

2009-07-14

223

Fluorescent Graphene Oxide via Polymer Grafting: An Efficient Nanocarrier for Both Hydrophilic and Hydrophobic Drugs.  

PubMed

Functionalized graphene-based drug delivery vehicles have conquered a significant position because functionalization improves its biocompatibility and stability in cell medium, leaving sufficient graphitic basal plane for drug loading through ?-? stacking. In this study, poly(N-isopropylacrylamide) (PNIPAM) is covalently grafted from the surface of graphene oxide (GO) via a facile, eco-friendly and an easy procedure of free radical polymerization (FRP) using ammonium persulfate initiator. Various spectroscopic and microscopic studies confirm the successful grafting of PNIPAM from GO surface. PNIPAM-grafted GO (GPNM) exhibits enhanced thermal stability, improved dispersibility both in aqueous and cell medium, and better biocompatibility and cell viability compared to GO. Interestingly, GPNM displays an exciting fluorescence property in aqueous medium, which is a hike of intensity at 36 °C due to the lower critical solution temperature (LCST) of PNIPAM chains (32 °C). Moreover both hydrophilic (doxorubicin (DOX)) and hydrophobic (indomethacin (IMC)) drugs loaded on the surface of GPNM hybrid exhibits its efficacy as an efficient carrier for both types of drugs. Cellular uptakes of free DOX and DOX-loaded GPNM (GPNM-DOX) are evidenced both from optical and fluorescence imaging of live cells, and the efficiency of drug is significantly improved in the loaded system. The release of DOX from GPNM-DOX was achieved at pH 4, relevant to the environment of cancer cells. The pH-triggered release of hydrophobic drug was also studied using UV-vis spectroscopy via alginate encapsulation, showing a great enhancement at pH = 7.4. The IMC is also found to be released by human serum albumin using dialysis technique. The GPNM nanomaterial shows the property of simultaneous loading of DOX and IMC as well as pH-triggered simultaneous release of both of the drugs. PMID:25612470

Kundu, Aniruddha; Nandi, Sudipta; Das, Pradip; Nandi, Arun K

2015-02-18

224

Oxide dispersed copper alloys by surface oxidation  

Microsoft Academic Search

A series of Cu-Al and Cu-Ni-Al alloys, inert gas atomized, as -44 ? powders, were converted to submicron thick flakes covered\\u000a by copper oxide and aluminum oxide in varying amounts, depending on the initial aluminum content. The flake powders were either\\u000a hydrogen reduced to eliminate copper oxide, or were reacted in a hot inert gas to increase the Al2O3 content

William F. Schilling; Nicholas J. Grant

1970-01-01

225

Oxide dispersed copper alloys by surface oxidation  

Microsoft Academic Search

A series of Cu-Al and Cu-Ni-Al alloys, inert gas atomized, as -44 mu powders, were converted to submicron thick flakes covered by copper oxide and aluminum oxide in varying amounts, depending on the initial aluminum content. The flake powders were either hydrogen reduced to eliminate copper oxide, or were reacted in a hot inert gas to increase the Al2O3 content

William F. Schilling; Nicholas J. Grant

1970-01-01

226

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

227

Biofiltration of nitric oxide  

SciTech Connect

Results of recent experiments on nitrogen transformations in biofilters suggest that oxides of nitrogen may be both oxidized or reduced within these systems. Under the proper conditions, nitric oxide (+2) can be reduced to molecular nitrogen (0) through microbial denitrification, or nitric oxide can be sequentially oxidized to nitrite (+3) and then to nitrate (+5) through microbial nitrification. There are major implications of these findings for the use of biofilters as air pollution control devices since economical NO{sub x} control technologies may be possible and should be exploited. Oxidation of ammonia ({minus}3) to nitrite (+3) by bacteria of the genus Nitrosomonas and oxidation of nitrite (+3) to nitrate (+5) by bacteria of the genus Nitrobacter are ubiquitous reactions in soil and natural waters. The intermediates, nitrous oxide (+1) and nitric oxide (+2) are potentially oxidizable by nitrifying bacteria in the presence of atmospheric concentration of oxygen. The oxidation of nitric oxide within a biofilter was demonstrated. The authors have observed removal up to 70% in laboratory scale aerobic biofilters with a NO feed of 80 ppmv and an empty bed contact time of 12 minutes. Nitric oxide removal appears to be linear with nitric oxide concentration. Removal rates are a function of the flow rate of the gas, suggesting diffusion limitations. The biofilter system was sensitive to pH changes resulting from nitrification. Improved removal efficiency at shorter contact times may be possible with increased biomass and better distribution.

Davidova, Y.B.; Schroeder, E.D.; Chang, D.P.Y. [Univ. of California, Davis, CA (United States). Dept. of Civil and Environmental Engineering

1997-12-31

228

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

229

Zinc oxide overdose  

MedlinePLUS

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

230

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

231

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.

232

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.

233

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

234

Comparison of the Catalytic Oxidation Reaction on Graphene Oxide and Reduced Graphene Oxide  

E-print Network

Comparison of the Catalytic Oxidation Reaction on Graphene Oxide and Reduced Graphene Oxide Laboratory (PAL), Pohang 790-784, Republic of Korea ABSTRACT: The capacities of graphene oxide (GO) and reduced graphene oxide (rGO) films grown on silicon substrate to cause the aniline to azobenzene oxidation

Kim, Sehun

235

Periodontal treatment decreases plasma oxidized LDL level and oxidative stress  

Microsoft Academic Search

Periodontitis induces excessive production of reactive oxygen species in periodontal lesions. This may impair circulating\\u000a pro-oxidant\\/anti-oxidant balance and induce the oxidation of low-density lipoprotein (LDL) in blood. The purpose of this study\\u000a was to monitor circulating oxidized LDL and oxidative stress in subjects with chronic periodontitis following non-surgical\\u000a periodontal treatment. Plasma levels of oxidized LDL and oxidative stress in 22

Naofumi Tamaki; Takaaki Tomofuji; Daisuke Ekuni; Reiko Yamanaka; Manabu Morita

236

Oxidation Resistant Graphite Studies  

SciTech Connect

The Very High Temperature Reactor (VHTR) Graphite Research and Development Program is investigating doped nuclear graphite grades exhibiting oxidation resistance. During a oxygen ingress accident the oxidation rates of the high temperature graphite core region would be extremely high resulting in significant structural damage to the core. Reducing the oxidation rate of the graphite core material would reduce the structural effects and keep the core integrity intact during any air-ingress accident. Oxidation testing of graphite doped with oxidation resistant material is being conducted to determine the extent of oxidation rate reduction. Nuclear grade graphite doped with varying levels of Boron-Carbide (B4C) was oxidized in air at nominal 740°C at 10/90% (air/He) and 100% air. The oxidation rates of the boronated and unboronated graphite grade were compared. With increasing boron-carbide content (up to 6 vol%) the oxidation rate was observed to have a 20 fold reduction from unboronated graphite. Visual inspection and uniformity of oxidation across the surface of the specimens were conducted. Future work to determine the remaining mechanical strength as well as graphite grades with SiC doped material are discussed.

W. Windes; R. Smith

2014-07-01

237

Oxide surface science.  

PubMed

Most metals are oxidized under ambient conditions, and metal oxides show interesting and technologically promising properties. This has motivated much recent research on oxide surfaces. The combination of scanning tunneling microscopy with first-principles density functional theory-based computational techniques provides an atomic-scale view of the properties of metal-oxide materials. Surface polarity is a key concept for predicting the stability of oxide surfaces and is discussed using ZnO as an example. This review also highlights the role of surface defects for surface reactivity, and their interplay with defects in the bulk, for the case of TiO(2). Ultrathin metal-oxide films, grown either through reactive evaporation on metal single crystals or through oxidation of metal alloys (such as Al(2)O(3)/NiAl), have gained popularity as supports for planar model catalysts. The surface oxides that form upon oxidation on Pt-group metals (e.g., Ru, Rh, Pd, and Pt) are considered as model systems for CO oxidation. PMID:20055675

Diebold, Ulrike; Li, Shao-Chun; Schmid, Michael

2010-01-01

238

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

239

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.

240

Multifunctional Oxide Heterostructures  

SciTech Connect

This book is devoted to the rapidly developing field of oxide thin-films and heterostructures. Oxide materials combined with atomic-scale precision in a heterostructure exhibit an abundance of macroscopic physical properties involving the strong coupling between the electronic, spin, and structural degrees of freedom, and the interplay between magnetism, ferroelectricity, and conductivity. Recent advances in thin-film deposition and characterization techniques made possible the experimental realization of such oxide heterostructures, promising novel functionalities and device concepts.

Tsymbal, E Y [University of Nebraska, Lincoln; Dagotto, Elbio R [ORNL; Eom, Professor Chang-Beom [University of Wisconsin, Madison; Ramesh, Ramamoorthy [University of California, Berkeley

2012-01-01

241

The Atomic Structure of Oxide\\/Oxide Interface  

Microsoft Academic Search

The physical and chemical properties of thin or ultrathin oxide film deposited on another oxide bulk or thin film usually differ strongly from the bulk. The properties of the heterostructures ultimately rely on the structure and the chemistry of the oxide\\/oxide interface. Data in the literature indicated that atomically abrupt interfaces between oxides show abnormal electronic and magnetic properties. This

Qi-Hui Wu

2011-01-01

242

Numerical simulation of in-situ chemical oxidation (ISCO) and biodegradation of petroleum hydrocarbons using a coupled model for bio-geochemical reactive transport  

NASA Astrophysics Data System (ADS)

Petroleum hydrocarbons (PHCs) are a major source of groundwater contamination, being a worldwide and well-known problem. Formed by a complex mixture of hundreds of organic compounds (including BTEX - benzene, toluene, ethylbenzene and xylenes), many of which are toxic and persistent in the subsurface and are capable of creating a serious risk to human health. Several remediation technologies can be used to clean-up PHC contamination. In-situ chemical oxidation (ISCO) and intrinsic bioremediation (IBR) are two promising techniques that can be applied in this case. However, the interaction of these processes with the background aquifer geochemistry and the design of an efficient treatment presents a challenge. Here we show the development and application of BIONAPL/Phreeqc, a modeling tool capable of simulating groundwater flow, contaminant transport with coupled biological and geochemical processes in porous or fractured porous media. BIONAPL/Phreeqc is based on the well-tested BIONAPL/3D model, using a powerful finite element simulation engine, capable of simulating non-aqueous phase liquid (NAPL) dissolution, density-dependent advective-dispersive transport, and solving the geochemical and kinetic processes with the library Phreeqc. To validate the model, we compared BIONAPL/Phreeqc with results from the literature for different biodegradation processes and different geometries, with good agreement. We then used the model to simulate the behavior of sodium persulfate (NaS2O8) as an oxidant for BTEX degradation, coupled with sequential biodegradation in a 2D case and to evaluate the effect of inorganic geochemistry reactions. The results show the advantages of a treatment train remediation scheme based on ISCO and IBR. The numerical performance and stability of the integrated BIONAPL/Phreeqc model was also verified.

Marin, I. S.; Molson, J. W.

2013-05-01

243

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

244

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

245

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

246

Lagoons and Oxidation Ponds.  

ERIC Educational Resources Information Center

Presents the 1978 literature review of wastewater treatment. This review covers lagoons and oxidation ponds, and it includes some areas such as improving the effluents from ponds, stabilization ponds, aerated lagoons, and oxidation ditches. A list of 36 references is also presented. (HM)

O'Brien, W. J.

1978-01-01

247

Oxides, Oxides, and More Oxides: High-? Oxides, Ferroelectrics, Ferromagnetics, and Multiferroics  

Microsoft Academic Search

We review and critique the recent developments on multifunctional oxide materials, which are gaining a good deal of interest. Recongnizing that this is a vast area, the focus of this treatment is mainly on high-? dielectric, ferroelectric, magnetic, and multiferroic materials. Also, we consider ferrimagnetic oxides in the context of the new, rapidly developing field of negative-index metamaterials. This review

N. Izyumskaya; Ya. Alivov; H. Morkoç

2009-01-01

248

OXIDATION OF CHLORINATED ETHANES  

EPA Science Inventory

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

249

Oxide dispersion strengthened superalloy  

NASA Technical Reports Server (NTRS)

MA6000E alloy is strengthened at high temperatures by dispersion of yttrium oxide. Strength properties are about twice those of conventional nickel base alloys. Good thermal fatigue, intermediate temperature strength, and good oxidation resistance give alloy unique combination of benefits. Application in aircraft gas turbine is improved.

Glasgow, T. K.; Kim, Y. G.; Curwick, L. R.; Merrick, H. F.

1981-01-01

250

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

251

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

252

Stabilized chromium oxide film  

Microsoft Academic Search

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.

A. R. Nyaiesh; E. L. Garwin

1986-01-01

253

Nitrous oxide pneumoperitoneum revisited  

Microsoft Academic Search

Nitrous oxide has been effectively banned from use in therapeutic laparoscopy because of fear of combustion. These fears rest on two case reports, a misunderstanding of the physical chemistry of nitrous oxide, and lack of information on the presence of flammable colonic gases in the pneumoperitoneum mixture. This study aims to identify the presence and quantify the amount of hydrogen

J. G. Hunter; J. Staheli; M. Oddsdottir; T. Trus

1995-01-01

254

Graphene oxide reinforced concrete  

E-print Network

Graphene oxide reinforced concrete CRICOS provider: Monash University 00008CAustrAliA CHiNA i and durability through the incorporation of graphene oxide (GO). Ordinary Portland Cement (OPC) is widely used is owned by Monash and is protected by PCT/ AU2012/001582. Comparison of mechanical parameters of graphene

Albrecht, David

255

Lipid oxidation in foods  

Microsoft Academic Search

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

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

1996-01-01

256

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

257

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...

258

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

259

Exploiting Covalency to Enhance MetalOxide and OxideOxide Adhesion at Heterogeneous Interfaces  

E-print Network

protec- tion, and protection against hot oxidation/corrosion are especially vital properties the aluminum content in the bond-coat alloy, since alumina (Al2O3) provides a slow-growing oxideExploiting Covalency to Enhance Metal­Oxide and Oxide­Oxide Adhesion at Heterogeneous Interfaces

Carter, Emily A.

260

Oxidative damage and carcinogenesis  

PubMed Central

Oxygen is an essential element to conduct life processes but some of the metabolic byproducts e.g. reactive oxygen species (ROS), are toxic for living organisms. Endogenous ROS are produced e.g. reduction of dioxygen; some exogenous sources of radicals also exist, including nicotine and ionizing radiation. Reactive oxygen species include superoxide anion, hydroxyl radical, singlet oxygen, hydrogen peroxide and hypochlorous acid. Carcinogenesis is a multistep process. The exact reasons for the development of cancer are still unknown. Many factors contribute to the development of carcinogenesis, one of which is oxidative stress. Oxidative stress is defined as an imbalance between oxidizing agents (pro-oxidants) and antioxidants, agents that protect biomolecules against injury by pro-oxidants. When reactive oxygen species are overproduced it can damage nucleic acids, proteins and lipids. ROS are considered as a significant class of carcinogens participating in cancer initiation, promotion and progression. PMID:23788885

Wiczkowski, Andrzej

2012-01-01

261

Structures of Selenomonas ruminantium Phytase in Complex with Persulfated Phytate  

Microsoft Academic Search

Various inositide phosphatases participate in the regulation of inositol polyphosphate signaling molecules. Plant phytases are phosphatases that hydrolyze phytate to less-phosphorylated myo-inositol derivatives and phosphate. The phytase from Selenomonas ruminantium shares no sequence homology with other microbial phytases. Its crystal structure revealed a phytase fold of the dual-specificity phosphatase type. The active site is located near a conserved cysteine-containing (Cys241)

Hsing-Mao Chu; Rey-Ting Guo; Ting-Wan Lin; Chia-Cheng Chou; Hui-Lin Shr; Hui-Lin Lai; Tsung-Yin Tang; Kuo-Joan Cheng; Brent L. Selinger; Andrew H.-J. Wang

2004-01-01

262

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

PubMed

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

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

2010-07-29

263

Transpassive oxidation of pyrite  

SciTech Connect

The electrochemical behavior of mineral and coal pyrites in basic borate/sulfate solutions was investigated using cyclic voltammetry with both stationary and rotating disk electrode. Emphasis was centered on transpassive oxidation. In the transpassive region, 0.4 to 0.8 V (SCE), aggressive oxidation of pyrite occurred. The reaction products in this region are Fe(III) oxides, sulfate ion, and partially oxidized sulfur intermediates. The formation of sulfur and polysulfides was identified by in situ Raman spectroscopy. Exposure of pyrite to anodic potentials higher than the transpassive region resulted in rapid oxidation of sulfur intermediates to sulfate ion. The effect of electrode rotation speed, electrode precondition time, and upper potential of the scan in the transpassive region was observed to be critical to the formation of sulfur intermediates. Sulfur intermediates, formed in the transpassive region, dramatically affected subsequent oxidation reactions occurring in the lower potential region. The magnitude of two dominant oxidation peaks, a ferrous hydroxide peak and an iron sulfide peak, observed in this region correlated directly with the quantity of sulfur intermediates formed in the transpassive region. This effect was less pronounced for coal pyrites compared to mineral pyrite.

Zhu, Ximeng; Bodily, D.M.; Wadsworth, M.E. (Univ. of Utah, Salt Lake City (United States). College of Mines and Earth Sciences)

1993-07-01

264

Parameters influencing cholesterol oxidation.  

PubMed

The purpose of this study was to investigate the effects of temperature, oxidation time, presence of water, pH, type of buffer and form of substrate used on cholesterol oxidation. Microcrystalline cholesterol films, both solid and melted, and aqueous suspensions of film fragments were used as substrates. Use of dispersing agents was avoided. Quantitative analysis of the unaltered substrate and the products of its autoxidation was carried out by gas chromatography over the course of oxidation. Solid cholesterol films were found to be resistant to autoxidation in the dry state. However, when heated at 125 degrees C, a sudden increase in oxidation rate occurred at a point coinciding with the visible melting followed by a plateau of the oxidation rate. All of the autoxidation products formed underwent further decomposition. Film fragments of cholesterol oxidized at a faster rate in aqueous suspensions than when oxidized in the dry state. In aqueous suspensions, the differences in the resistance of cholesterol to oxidation were not significant within the pH range 6.0-7.4, except for the early stages of oxidation. The 7-ketocholesterol/7-hydroxycholesterol ratio dropped significantly with increasing pH. However, at all pH levels tested, this ratio remained relatively constant during the 6 h of heating. While the 7 beta-hydroxycholesterol/7 alpha-hydroxycholesterol ratio was not affected by pH in the range of 6.0-7.4, at pH 7.4 a high preference was observed for the cholesterol beta-epoxide over its alpha-isomer.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8246692

Kim, S K; Nawar, W W

1993-10-01

265

Dry Thermal Oxidation Process  

NSDL National Science Digital Library

In this YouTube video, created by Southwest Center for Microsystems Education (SCME), viewers can watch an animation on the dry thermal oxidation process. This animation "illustrates the chemistry of a dry thermal oxidation process that is used to grow silicon dioxide (SiO2) on a silicon (Si) wafer. In a dry oxidation process, oxygen gas (O2) interacts with the silicon atoms at the SiO2 - Si interface to form SiO2. This process is discussed in more detail in the Deposition Overview for MEMS Learning Module" which can be found on the SCME website along with supplementary materials. 

2014-07-08

266

Wet Oxidation Process  

NSDL National Science Digital Library

In this YouTube video, created by Southwest Center for Microsystems Education (SCME), viewers can watch an animation on the wet oxidation process. This animation "illustrates the chemistry of a wet thermal oxidation process that is used to grow silicon dioxide (SiO2) on a silicon (Si) wafer. In a wet oxidation process, water vapor (H2O) interacts with the silicon atoms at the SiO2-Si interface to form SiO2. This process is discussed in more detail in the Deposition Overview for MEMS Learning Module" found on the SCME website.

2014-07-07

267

Chemolithotrophic nitrite oxidation by Nitrobacter: coupling with carbon dioxide fixation for growth and influence of metal ions and inorganic compounds of sulfur  

SciTech Connect

The growth of Nitrobacter winogradskyi was completely inhibited by 0.1 mM persulfate, 0.5 mM tetrathionate, or by 5 mM each of dithionite, metabisulfite, or trithionate. The oxygen uptake activity of washed N. agilis cell suspensions was not influenced by persulfate or tetrathionate. Carbon dioxide fixation was insensitive to tetrathionate and in fact an enhancement by tetrathionate was observed. Persulfate inhibited the fixation of carbon dioxide only at a high concentration. The oxygen uptake activity of washed ell suspensions of N. agilis was tested in the presence of copper, nickel, aluminum, uranyl, and molybdate ions. Copper ion was slightly stimulatory at 0.17 M and strongly inhibitory at 17 mM. Molybdate ion showed either slight enhancement or no inhibition at all test concentrations. With the other test ions inhibition of oxygen uptake was observed.

Tsai, Y.L.

1986-01-01

268

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 ...

269

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

270

Stabilized chromium oxide film  

Microsoft Academic Search

This patent describes a coated ceramic RF window and metal sleeve of a klystron comprising a stabilized chromium oxide film less than 200 angstroms thick deposited on a ceramic RF window and metal sleeve.

E. L. Garwin; A. R. Nyaiesh

1988-01-01

271

Oxidative Tritium Decontamination System  

DOEpatents

The Oxidative Tritium Decontamination System, OTDS, provides a method and apparatus for reduction of tritium surface contamination on various items. The OTDS employs ozone gas as oxidizing agent to convert elemental tritium to tritium oxide. Tritium oxide vapor and excess ozone gas is purged from the OTDS, for discharge to atmosphere or transport to further process. An effluent stream is subjected to a catalytic process for the decomposition of excess ozone to diatomic oxygen. One of two configurations of the OTDS is employed: dynamic apparatus equipped with agitation mechanism and large volumetric capacity for decontamination of light items, or static apparatus equipped with pressurization and evacuation capability for decontamination of heavier, delicate, and/or valuable items.

Gentile, Charles A. (Plainsboro, NJ), Guttadora, Gregory L. (Highland Park, NJ), Parker, John J. (Medford, NJ)

2006-02-07

272

Parameters influencing cholesterol oxidation  

Microsoft Academic Search

The purpose of this study was to investigate the effects of temperature, oxidation time, presence of water, pH, type of buffer\\u000a and form of substrate used on cholesterol oxidation. Microcrystalline cholesterol films, both solid and melted, and aqueous\\u000a suspensions of film fragments were used as substrates. Use of dispersing agents was avoided. Quantitative analysis of the\\u000a unaltered substrate and the

S. K. Kim; W. W. Nawar

1993-01-01

273

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

274

Oxidative Stress in Schizophrenia  

PubMed Central

Increasing evidence indicates that oxidative damage exists in schizophrenia. Available literature about possible mechanisms of oxidative stress induction was reviewed. Furthermore, possibilities of measuring biomarkers of schizophrenia outside the central nervous system compartment, their specificity for different types of schizophrenia and potential therapeutic strategies to prevent oxidative injuries in schizophrenia were discussed. Data were extracted from published literature found in Medline, Embase, Biosis, Cochrane and Web of Science, together with hand search of references. Search terms were: schizophrenia, oxidative stress, antipsychotics, antioxidants and fatty acids. Finding a sensitive, specific and non invasive biomarker of schizophrenia, which could be measured in peripheral tissue, still stays an important task. Antioxidant enzymes, markers of lipid peroxidation, oxidatively modified proteins and DNA are most commonly used. As it considers the supplemental therapy, according to our meta-analysis vitamin E could potentially improve tardive dyskinesia, while for the effect of therapy with polyunsaturated fatty acids there is no clear evidence. Oxidative stress is a part of the pathology in schizophrenia and appears as a promising field to develop new therapeutic strategies. There is a need for well designed, placebo controlled trials with supplementation therapy in schizophrenia. PMID:22131939

Boškovi?, Marija; Vovk, Tomaž; Kores Plesni?ar, Blanka; Grabnar, Iztok

2011-01-01

275

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

276

Retention Reliability Improvement of Silicon-Oxide-Nitride-Oxide-Silicon Nonvolatile Memory with N2O Oxidation Tunnel Oxide  

Microsoft Academic Search

The reliability characteristics of silicon-oxide-nitride-oxide-silicon (SONOS) devices with different thin tunnel oxides are studied. The device with the tunnel oxynitride grown in pure N2O ambient at a high temperature has better performance, including better leakage current, programming speed, read-disturb, and retention characteristics, than that with a tunnel oxide layer grown by dry oxidation with N2 annealing treatment. Moreover, the properties

Jia-Lin Wu; Chin-Hsing Kao; Hua-Ching Chien; Tzung-Kuen Tsai; Chien-Wei Liao

2007-01-01

277

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

278

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

279

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

280

Erythropoietin and Oxidative Stress  

PubMed Central

Unmitigated oxidative stress can lead to diminished cellular longevity, accelerated aging, and accumulated toxic effects for an organism. Current investigations further suggest the significant disadvantages that can occur with cellular oxidative stress that can lead to clinical disability in a number of disorders, such as myocardial infarction, dementia, stroke, and diabetes. New therapeutic strategies are therefore sought that can be directed toward ameliorating the toxic effects of oxidative stress. Here we discuss the exciting potential of the growth factor and cytokine erythropoietin for the treatment of diseases such as cardiac ischemia, vascular injury, neurodegeneration, and diabetes through the modulation of cellular oxidative stress. Erythropoietin controls a variety of signal transduction pathways during oxidative stress that can involve Janus-tyrosine kinase 2, protein kinase B, signal transducer and activator of transcription pathways, Wnt proteins, mammalian forkhead transcription factors, caspases, and nuclear factor ?B. Yet, the biological effects of erythropoietin may not always be beneficial and may be poor tolerated in a number of clinical scenarios, necessitating further basic and clinical investigations that emphasize the elucidation of the signal transduction pathways controlled by erythropoietin to direct both successful and safe clinical care. PMID:18473829

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

2008-01-01

281

Effect of Surface Oxide Transformation on CO Oxidation  

NASA Astrophysics Data System (ADS)

Under sub-atmospheric conditions, many metal catalyst surfaces for CO oxidation transform to the oxide phase with higher catalytic activity than chemisorbed oxygen. The surface phase transformation from metal to its oxide could be by collective oxidation of the adsorbed oxygen sites as soon as their coverage reaches a global critical threshold, or such oxidation may be restricted to small patches of the surface, which is driven by the local coverage. In this communication, we investigate the effect of the latter on the phase diagram and the CO2 production rate behavior using a kinetic Monte Carlo surface reaction lattice gas model for CO oxidation.

Sinha, I.; Mukherjee, A. K.

2015-02-01

282

Methanol partial oxidation reformer  

DOEpatents

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

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

1999-08-24

283

Magnetism of cuprate oxides  

SciTech Connect

A review is given of current neutron scattering experiments on cuprate oxides. We first discuss the extensive neutron measurements on high-Tc oxides: La{sub 2-x}Sr{sub x}CuO{sub 4} and related (La{sub 1.6-x}Nd{sub 0.4})Sr{sub x}CuO{sub 4}. The second topic is the spin- Peierls system Cu{sub 1-x}Zn{sub x}GeO{sub 3}, where a new type of antiferromagnetic phase has been discovered. 17 refs, 8 figs.

Shirane, G.

1996-11-01

284

Molecular water oxidation catalyst  

DOEpatents

A dimeric composition of the formula: ##STR1## wherein L', L", L'", and L"" are each a bidentate ligand having at least one functional substituent, the ligand selected from bipyridine, phenanthroline, 2-phenylpyridine, bipyrimidine, and bipyrazyl and the functional substituent selected from carboxylic acid, ester, amide, halogenide, anhydride, acyl ketone, alkyl ketone, acid chloride, sulfonic acid, phosphonic acid, and nitro and nitroso groups. An electrochemical oxidation process for the production of the above functionally substituted bidentate ligand diaqua oxo-bridged ruthenium dimers and their use as water oxidation catalysts is described.

Gratzel, Michael (St. Sulpice, CH); Munavalli, Shekhar (Bel Air, MD); Pern, Fu-Jann (Lakewood, CO); Frank, Arthur J. (Lakewood, CO)

1993-01-01

285

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

286

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

287

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

288

Ultra-thin titanium oxide  

NASA Astrophysics Data System (ADS)

We demonstrate the fabrication of ultra-thin titanium oxide films by plasma-induced surface oxidation. Ellipsometry measurements indicate an oxide thickness of about 2 nm. Electrical characterization was performed on microscale and nanoscale metal-insulator-metal tunneling diodes. Electrical fields up to 22 MV/cm were applied without destroying the titanium oxide films. The current-voltage-characteristic of the diodes are found to be asymmetric with respect to zero bias when employing electrodes with different work functions. The permittivity of the ultra-thin titanium oxide was determined to be less than 6, which is the smallest permittivity that has been reported for titanium oxide.

Bareiß, M.; Kälblein, D.; Jirauschek, C.; Exner, A.; Pavlichenko, I.; Lotsch, B.; Zschieschang, U.; Klauk, H.; Scarpa, G.; Fabel, B.; Porod, W.; Lugli, P.

2012-08-01

289

Some Properties of Beryllium Oxide and Beryllium Oxide - Columbium Ceramals  

NASA Technical Reports Server (NTRS)

High-temperature tensile and thermal-shock investigations were conducted on beryllium oxide and beryllium oxide plus columbium metal additions. X-ray diffraction and metallographic results are given. The tensile strength of 6150 pounds per square inch for beryllium oxide at 1800 degrees F compared favorably with the zirconia bodies previously tested. Additions of 2, 5, 8, 10, 12, and 15 percent by weight of columbium metal failed to improve the shock resistance over that of pure beryllium oxide.

Robards, C F; Gangler, J J

1951-01-01

290

High dielectric constant gate oxides for metal oxide Si transistors  

Microsoft Academic Search

The scaling of complementary metal oxide semiconductor transistors has led to the silicon dioxide layer, used as a gate dielectric, being so thin (1.4 nm) that its leakage current is too large. It is necessary to replace the SiO2 with a physically thicker layer of oxides of higher dielectric constant (kappa) or 'high K' gate oxides such as hafnium oxide

John Robertson

2006-01-01

291

Oxidized Oligogalacturonides Activate the Oxidation of Indoleacetic Acid by Peroxidase  

PubMed Central

Partial hydrolysis of polygalacturonic acid with a purified ?-1,4-endopolygalacturonase yielded oligogalacturonides and trace amounts of a series of modified oligogalacturonides. Three of the minor products were isolated and identified as oxidized oligogalacturonides possessing termini of galactaric acid. Oxidation of indole-3-acetic acid by peroxidases was activated by oxidized oligogalacturonides but not by normal analogs. PMID:16668315

Pressey, Russell

1991-01-01

292

Catalytic oxidation of diesel particulates with base metal oxides  

Microsoft Academic Search

Reduction of emissions from diesel engines using novel flow-through oxidation catalysts containing base metal oxides has been demonstrated. The soluble organic fraction (SOF) of the particulates can be converted and gas phase hydrocarbons can be removed via the proper choice of oxides. Low levels of platinum on the catalysts also compliment HC and CO conversion without leading to “sulfate-make”. Catalyst

K. E. Voss; J. K. Lampert; R. J. Farrauto; G. W. Rice; A. Punke; R. Krohn

1995-01-01

293

Nanostructured transition metal oxides useful for water oxidation catalysis  

DOEpatents

The present invention provides for a composition comprising a nanostructured transition metal oxide capable of oxidizing two H.sub.2O molecules to obtain four protons. In some embodiments of the invention, the composition further comprises a porous matrix wherein the nanocluster of the transition metal oxide is embedded on and/or in the porous matrix.

Frei, Heinz M; Jiao, Feng

2013-12-24

294

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

295

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

296

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...

297

Metal oxide sensors  

Microsoft Academic Search

New gas sensors based on novel semiconducting metal oxides are developed. In comparison to the sensors based on SnO2 their properties are improved in several items. The main improvements are the lower influence of humidity, the long-term stability, the ability to start measurement immediately after switch on and reduced unit spread. The sensors will be marketed within this year.

H. Meixner; U. Lampe

1996-01-01

298

CONTROLLING SULFUR OXIDES  

EPA Science Inventory

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

299

Zinc oxide varistors  

Microsoft Academic Search

An overview is given of zinc oxide varistors, which are made of semiconducting ceramics with highly nonohmic current-voltage characteristics, which originate at the grain boundaries. These varistors are widely utilized to protect electric power lines and electronic components against dangerous voltage surges. This overview covers electrical characteristics, fabrication methods, effects of additives, microstructures, the conduction mechanism, degradation, and applications.<>

K. Eda

1989-01-01

300

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

301

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

302

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

303

SUPERCRITICAL WATER PARTIAL OXIDATION  

Microsoft Academic Search

In 2000, General Atomics was selected by DOE's Hydrogen Program to perform cooperatively- funded research on supercritical water partial oxidation (SWPO) of biomass, municipal solid waste (MSW), and high-sulfur coal to generate hydrogen. Phase I of this research is being performed in GA's privately-funded supercritical water (SCW) pilot plant at its San Diego, CA facilities. This pilot plant is a

N. W. Johanson; M. H. Spritzer; G. T. Hong; W. S. Rickman

304

Active oxide nanophotonics  

NASA Astrophysics Data System (ADS)

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

Dicken, Matthew J.

305

ChemTeacher: Oxidation States  

NSDL National Science Digital Library

ChemTeacher compiles background information, videos, articles, demonstrations, worksheets and activities for high school teachers to use in their classrooms. The Oxidation States page includes resources for teaching students about determining oxidation states of atoms within compounds.

2011-01-01

306

Staged membrane oxidation reactor system  

DOEpatents

Ion transport membrane oxidation system comprising (a) two or more membrane oxidation stages, each stage comprising a reactant zone, an oxidant zone, one or more ion transport membranes separating the reactant zone from the oxidant zone, a reactant gas inlet region, a reactant gas outlet region, an oxidant gas inlet region, and an oxidant gas outlet region; (b) an interstage reactant gas flow path disposed between each pair of membrane oxidation stages and adapted to place the reactant gas outlet region of a first stage of the pair in flow communication with the reactant gas inlet region of a second stage of the pair; and (c) one or more reactant interstage feed gas lines, each line being in flow communication with any interstage reactant gas flow path or with the reactant zone of any membrane oxidation stage receiving interstage reactant gas.

Repasky, John Michael; Carolan, Michael Francis; Stein, VanEric Edward; Chen, Christopher Ming-Poh

2014-05-20

307

Staged membrane oxidation reactor system  

DOEpatents

Ion transport membrane oxidation system comprising (a) two or more membrane oxidation stages, each stage comprising a reactant zone, an oxidant zone, one or more ion transport membranes separating the reactant zone from the oxidant zone, a reactant gas inlet region, a reactant gas outlet region, an oxidant gas inlet region, and an oxidant gas outlet region; (b) an interstage reactant gas flow path disposed between each pair of membrane oxidation stages and adapted to place the reactant gas outlet region of a first stage of the pair in flow communication with the reactant gas inlet region of a second stage of the pair; and (c) one or more reactant interstage feed gas lines, each line being in flow communication with any interstage reactant gas flow path or with the reactant zone of any membrane oxidation stage receiving interstage reactant gas.

Repasky, John Michael; Carolan, Michael Francis; Stein, VanEric Edward; Chen, Christopher Ming-Poh

2012-09-11

308

Staged membrane oxidation reactor system  

DOEpatents

Ion transport membrane oxidation system comprising (a) two or more membrane oxidation stages, each stage comprising a reactant zone, an oxidant zone, one or more ion transport membranes separating the reactant zone from the oxidant zone, a reactant gas inlet region, a reactant gas outlet region, an oxidant gas inlet region, and an oxidant gas outlet region; (b) an interstage reactant gas flow path disposed between each pair of membrane oxidation stages and adapted to place the reactant gas outlet region of a first stage of the pair in flow communication with the reactant gas inlet region of a second stage of the pair; and (c) one or more reactant interstage feed gas lines, each line being in flow communication with any interstage reactant gas flow path or with the reactant zone of any membrane oxidation stage receiving interstage reactant gas.

Repasky, John Michael; Carolan, Michael Francis; Stein, VanEric Edward; Chen, Christopher Ming-Poh

2013-04-16

309

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

310

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

311

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

312

Oxidative phosphorylation revisited.  

PubMed

The fundamentals of oxidative phosphorylation and photophosphorylation are revisited. New experimental data on the involvement of succinate and malate anions respectively in oxidative phosphorylation and photophosphorylation are presented. These new data offer a novel molecular mechanistic explanation for the energy coupling and ATP synthesis carried out in mitochondria and chloroplast thylakoids. The mechanism does not suffer from the flaws in Mitchell's chemiosmotic theory that have been pointed out in many studies since its first appearance 50 years ago, when it was hailed as a ground-breaking mechanistic explanation of what is perhaps the most important process in cellular energetics. The new findings fit very well with the predictions of Nath's torsional mechanism of energy transduction and ATP synthesis. It is argued that this mechanism, based on at least 15 years of experimental and theoretical work by Sunil Nath, constitutes a fundamentally different theory of the energy conversion process that eliminates all the inconsistencies in Mitchell's chemiosmotic theory pointed out by other authors. It is concluded that the energy-transducing complexes in oxidative phosphorylation and photosynthesis are proton-dicarboxylic acid anion cotransporters and not simply electrogenic proton translocators. These results necessitate revision of previous theories of biological energy transduction, coupling, and ATP synthesis. The novel molecular mechanism is extended to cover ATP synthesis in prokaryotes, in particular to alkaliphilic and haloalkaliphilic bacteria, essentially making it a complete theory addressing mechanistic, kinetic, and thermodynamic details. Finally, based on the new interpretation of oxidative phosphorylation, quantitative values for the P/O ratio, the amount of ATP generated per redox package of the reduced substrates, are calculated and compared with experimental values for fermentation on different substrates. It is our hope that the presentation of oxidative phosphorylation and photophosphorylation from a wholly new perspective will rekindle scientific discussion of a key process in bioenergetics and catalyze new avenues of research in a truly interdisciplinary field. Biotechnol. Bioeng. 2015;112: 429-437. © 2014 Wiley Periodicals, Inc. PMID:25384602

Nath, Sunil; Villadsen, John

2015-03-01

313

REVIEW OF PLUTONIUM OXIDATION LITERATURE  

SciTech Connect

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

Korinko, P.

2009-11-12

314

Adsorption of Sodium Hexanoate on ?-Alumina  

E-print Network

carbons and sodium persulfate as oxidizer supplied by GE Analytical instruments Ltd. The adsorption isotherm of sodium hexanoate was determined by the solution depletion method, where the change in adsorbate concentration (depletion) after contact...

Lee, Seung Yeon; Welbourn, Rebecca; Clarke, Stuart; Skoda, Maximilian W. A.; Clifton, Luke; Zarbakhsh, Ali

2013-06-27

315

Correlated Oxides and Oxide Interfaces Workshop William I. Fine Theoretical Physics Institute, University of Minnesota  

E-print Network

Correlated Oxides and Oxide Interfaces Workshop William I. Fine Theoretical Physics Institute Barbara Strong Electron Correlations in Oxide Quantum Wells #12;Acknowledgements Graduate students strong electron correlations in oxide heterostructures Magnetism and non-Fermi liquid behavior in oxide

Akhmedov, Azer

316

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

317

5, 29472971, 2005 Isoprene oxidation  

E-print Network

ACPD 5, 2947­2971, 2005 Isoprene oxidation products in boreal forest aerosols I. Kourtchev et al Commons License. 2947 #12;ACPD 5, 2947­2971, 2005 Isoprene oxidation products in boreal forest aerosols I summer in this conifer forest ecosystem. In addition to isoprene oxidation products, malic acid, which

Paris-Sud XI, Université de

318

7, 1515515188, 2007 Nitrogen Oxide  

E-print Network

ACPD 7, 15155­15188, 2007 Nitrogen Oxide biogenic emissions from soils C. Delon et al. Title Page Chemistry and Physics Discussions Nitrogen Oxide biogenic emissions from soils: impact on NOx and ozone@aero.obs-mip.fr) 15155 #12;ACPD 7, 15155­15188, 2007 Nitrogen Oxide biogenic emissions from soils C. Delon et al. Title

Boyer, Edmond

319

Doped palladium containing oxidation catalysts  

DOEpatents

A supported oxidation catalyst includes a support having a metal oxide or metal salt, and mixed metal particles thereon. The mixed metal particles include first particles including a palladium compound, and second particles including a precious metal group (PMG) metal or PMG metal compound, wherein the PMG metal is not palladium. The oxidation catalyst may also be used as a gas sensor.

Mohajeri, Nahid

2014-02-18

320

The chemistry of graphene oxide  

Microsoft Academic Search

The chemistry of graphene oxide is discussed in this critical review. Particular emphasis is directed toward the synthesis of graphene oxide, as well as its structure. Graphene oxide as a substrate for a variety of chemical transformations, including its reduction to graphene-like materials, is also discussed. This review will be of value to synthetic chemists interested in this emerging field

Daniel R. Dreyer; Sungjin Park; Christopher W. Bielawski; Rodney S. Ruoff

2010-01-01

321

Reduced Graphene Oxide Molecular Sensors  

Microsoft Academic Search

We demonstrate reduced graphene oxide as the active material for high-performance molecular sensors. Sensors are fabricated from exfoliated graphene oxide platelets that are deposited to form an ultrathin continuous network. These graphene oxide networks are tunably reduced toward graphene by varying the exposure time to a hydrazine hydrate vapor. The conductance change of the networks upon exposure to trace levels

Jeremy T. Robinson; F. Keith Perkins; Eric S. Snow; Zhongqing Wei; Paul E. Sheehan

2008-01-01

322

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

323

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

324

Wet vs. Dry Oxidation Processes  

NSDL National Science Digital Library

In this YouTube video, created by Southwest Center for Microsystems Education (SCME), viewers can watch an animation on the the difference between wet and dry thermal oxidation processes. This animation "shows a side by side comparison of a wet oxidation process vs. a dry oxidation process. Both processes use an oxygen source to grow silicon dioxide (SiO2) on a silicon wafer heated furnace. Wet thermal oxidation uses water vapor. Dry thermal oxidation uses oxygen gas." Viewers can learn more on this topic in the Deposition Overview for MEMS Learning Module which can be found on the SCME website along with supplementary materials. 

2014-07-09

325

Selective oxidation using gold.  

PubMed

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

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

2008-09-01

326

Nitric oxide donor superparamagnetic iron oxide nanoparticles.  

PubMed

This work reports a new strategy for delivering nitric oxide (NO), based on magnetic nanoparticles (MNPs), with great potential for biomedical applications. Water-soluble magnetic nanoparticles were prepared through a co-precipitation method by using ferrous and ferric chlorides in acidic solution, followed by a mercaptosuccinic acid (MSA) coating. The thiolated nanoparticles (SH-NPs) were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM). The results showed that the SH-NPs have a mean diameter of 10nm and display superparamagnetic behavior at room temperature. Free thiol groups on the magnetite surface were nitrosated through the addition of an acidified nitrite solution, yielding nitrosated magnetic nanoparticles (SNO-NPs). The amount of NO covalently bound to the nanoparticles surface was evaluated by chemiluminescense. The SNO-NPs spontaneously released NO in aqueous solution at levels required for biomedical applications. This new magnetic NO-delivery vehicle has a great potential to generate desired amounts of NO directed to the target location. PMID:25427482

Molina, Miguel M; Seabra, Amedea B; de Oliveira, Marcelo G; Itri, Rosangela; Haddad, Paula S

2013-03-01

327

Controlled CO preferential oxidation  

DOEpatents

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

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

1997-01-01

328

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

329

Oxidative Stress in Malaria  

PubMed Central

Malaria is a significant public health problem in more than 100 countries and causes an estimated 200 million new infections every year. Despite the significant effort to eradicate this dangerous disease, lack of complete knowledge of its physiopathology compromises the success in this enterprise. In this paper we review oxidative stress mechanisms involved in the disease and discuss the potential benefits of antioxidant supplementation as an adjuvant antimalarial strategy. PMID:23208374

Percário, Sandro; Moreira, Danilo R.; Gomes, Bruno A. Q.; Ferreira, Michelli E. S.; Gonçalves, Ana Carolina M.; Laurindo, Paula S. O. C.; Vilhena, Thyago C.; Dolabela, Maria F.; Green, Michael D.

2012-01-01

330

Preparation of oxide superconductors  

SciTech Connect

Preparation of bulk superconductors by cold pressing and sintering of metal oxides has been optimized in this study. A knowledge of phase behavior was used in developing a flux method for growing superconducting single crystals of yttrium and gadolinium based superconductors. Means of achieving single-phase, high-density samples of (Rare Earth)-Ba/sub 2/Cu/sub 3/O/sub 7/ with optimal electronic properties are reviewed. 2 refs., 2 figs.

Peterson, D.E.

1988-01-01

331

Cuprous oxide photovoltaic cells  

Microsoft Academic Search

Cuprous oxide, with a band gap of 2.0 eV, is an attractive material for solar cells because of low cost and great availability. The current conversion efficiency is 1 percent, but theoretical estimates are greater than 13 percent. For various Schottky barriers, e.g., Al\\/Cu2O, it is proposed that the V\\/sub oc\\/ is limited by chemical conversion of the junctions to

D. Trivich; E. Y. Wang; R. J. Komp; A. S. Kakar

1978-01-01

332

Oxide Ferromagnetic Semiconductors  

NASA Astrophysics Data System (ADS)

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

Ogale, Satishchandra

2006-03-01

333

Anodic Aluminum Oxide Diodes  

NASA Astrophysics Data System (ADS)

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

Chang, Cheng-Yao; Wang, Gou-Jen

2011-07-01

334

Iridium oxide-polymer nanocomposite electrode materials for water oxidation.  

PubMed

Nanocomposite anode materials for water oxidation have been readily synthesized by electrodeposition of iridium oxide nanoparticles into poly(pyrrole-alkylammonium) films, previously deposited onto carbon electrodes by oxidative electropolymerization of a pyrrole-alkylammonium monomer. The nanocomposite films were characterized by electrochemistry, transmission electron microscopy, and atomic force microscopy. They showed an efficient electrocatalytic activity toward the oxygen evolution reaction. Data from Tafel plots have demonstrated that the catalytic activity of the iridium oxide nanoparticles is maintained following their inclusion in the polymer matrix. Bulk electrolysis of water at carbon foam modified electrodes have shown that the iridium oxide-polymer composite presents a higher catalytic activity and a better operational stability than regular oxide films. PMID:25045786

Lattach, Youssef; Rivera, Juan Francisco; Bamine, Tahya; Deronzier, Alain; Moutet, Jean-Claude

2014-08-13

335

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

336

Oxidative Denitrogenation of Coal Liquids  

NASA Astrophysics Data System (ADS)

The oxidative denitrogenation of quinoline (as a model compound representing the nitrogen containing structure of coal liquids) has been investigated in two steps: oxidation by perdecanoic acid at 50 °C to produce quinoline N-oxide in order to weaken the nitrogen-carbon bond; thermal decomposition of quinoline N-oxide to remove nitrogen as its respective oxides. Quinoline is successfully converted to quinoline N-oxide in the oxidation step. Thermal decomposition of quinoline N-oxide at 400 °C and 600 kPa of N2 produces 52-wt% quinoline, 22-wt% a condensed polymeric compound and 26-wt% gaseous mixture of CO2, CO and O2. Almost all the nitrogen content of quinoline N-oxide has remained in the residue of decomposition reaction. This confirms that thermal decomposition not only fails to remove nitrogen from structure of the oxidized molecule, but it also leads to production of a more complex aromatic structure with 10.4-wt% nitrogen content, compared to 10.6-wt% nitrogen content of quinoline.

Mirshamsi, Sepideh

337

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

338

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

339

Arsenic doped zinc oxide  

SciTech Connect

As-doping of zinc oxide has been approached by ion implantation and chemical vapor deposition. The effect of thermal annealing on the implanted samples has been investigated by using secondary ion mass spectrometry and Rutherford backscattering/channeling geometry. The crystal damage, the distribution of the arsenic, the diffusion of impurities, and the formation of secondary phases is discussed. For the thin films grown by vapor deposition, the composition has been determined with regard to the growth parameters. The bonding state of arsenic was investigated for both series of samples using x-ray photoelectron spectroscopy.

Volbers, N.; Lautenschlaeger, S.; Leichtweiss, T.; Laufer, A.; Graubner, S.; Meyer, B. K. [Physics Institute, Justus-Liebig-Universitaet Giessen, Heinrich-Buff-Ring 16, 35392 Giessen (Germany); Potzger, K.; Zhou Shengqiang [Institute for Ion Beam Physics and Materials Research, Forschungszentrum Dresden-Rossendorf, P.O. Box 51 01 19, D-01314 Dresden (Germany)

2008-06-15

340

Oxidative Metabolism in Muscle  

NASA Astrophysics Data System (ADS)

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

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

1997-06-01

341

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

342

Retention Reliability Improvement of Silicon-Oxide-Nitride-Oxide-Silicon Nonvolatile Memory with N2O Oxidation Tunnel Oxide  

NASA Astrophysics Data System (ADS)

The reliability characteristics of silicon-oxide-nitride-oxide-silicon (SONOS) devices with different thin tunnel oxides are studied. The device with the tunnel oxynitride grown in pure N2O ambient at a high temperature has better performance, including better leakage current, programming speed, read-disturb, and retention characteristics, than that with a tunnel oxide layer grown by dry oxidation with N2 annealing treatment. Moreover, the properties of two-bit operation are also displayed by a reverse read method. Furthermore, the surface roughness and interface states between a tunnel oxide layer and a Si substrate are also observed by atomic force microscopy (AFM) and charge-pumping method to evaluate interfacial nitrogen incorporation. The results show that data retention reliability attained a significant improvement while maintaining good programming/erase performance and two-bit operation. This work can provide a straightforward way of reliability improvement for future flash memory application.

Wu, Jia-Lin; Kao, Chin-Hsing; Chien, Hua-Ching; Tsai, Tzung-Kuen; Liao, Chien-Wei

2007-10-01

343

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

344

Buried oxide layer in silicon  

DOEpatents

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

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

2001-01-01

345

Continuous lengths of oxide superconductors  

DOEpatents

A layered oxide superconductor prepared by depositing a superconductor precursor powder on a continuous length of a first substrate ribbon. A continuous length of a second substrate ribbon is overlaid on the first substrate ribbon. Sufficient pressure is applied to form a bound layered superconductor precursor powder between the first substrate ribbon and the second substrate ribbon. The layered superconductor precursor is then heat treated to establish the oxide superconducting phase. The layered oxide superconductor has a smooth interface between the substrate and the oxide superconductor.

Kroeger, Donald M. (Knoxville, TN); List, III, Frederick A. (Andersonville, TN)

2000-01-01

346

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

347

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

348

Graphene oxide nanocolloids.  

PubMed

Graphene oxide (GO) nanocolloids-sheets with lateral dimension smaller than 100 nm-were synthesized by chemical exfoliation of graphite nanofibers, in which the graphene planes are coin-stacked along the length of the nanofibers. Since the upper size limit is predetermined by the diameter of the nanofiber precursor, the size distribution of the GO nanosheets is much more uniform than that of common GO synthesized from graphite powders. The size can be further tuned by the oxidation time. Compared to the micrometer-sized, regular GO sheets, nano GO has very similar spectroscopic characteristics and chemical properties but very different solution properties, such as surface activity and colloidal stability. Due to higher charge density originating from their higher edge-to-area ratios, aqueous GO nanocolloids are significantly more stable. Dispersions of GO nanocolloids can sustain high-speed centrifugation and remain stable even after chemical reduction, which would result in aggregates for regular GO. Therefore, nano GO can act as a better dispersing agent for insoluble materials (e.g., carbon nanotubes) in water, creating a more stable colloidal dispersion. PMID:21105686

Luo, Jiayan; Cote, Laura J; Tung, Vincent C; Tan, Alvin T L; Goins, Philip E; Wu, Jinsong; Huang, Jiaxing

2010-12-22

349

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

350

Mesostructured zirconium oxide  

SciTech Connect

The supramolecular templating technique was used to synthesize both hexagonal (Hx-ZrO{sub 2}) and lamellar (L-ZrO{sub 2}) phases of zirconium oxide. Under the conditions used in this work, the use of long chain primary amines and quaternary ammonium surfactants resulted in the exclusive formation of lamellar and hexagonal phases, respectively. The use of long chain cetyldimethylamine afforded a mixture of a hexagonal and a lamellar phase. Effects of synthesis parameters such as the ZrO{sub 2}/surfactant ratio, ZrO{sub 2}/water ratio, the nature of surfactant, the crystallization temperature and time on the formation of mesostructured ZrO{sub 2} were also studied. Addition of 1,3,5-trimethylbenzene (TMB) as a swelling agent led, in the presence of cetyltrimethylammonium bromide, to the formation of a lamellar phase rather than to pore enlargement. These materials were characterized by XRD, FTIR, XPS and EDX techniques. Regardless of their structure, the as-synthesized materials collapsed upon calcination. Treatment with monobasic potassium phosphate followed by calcination at 350 C led to the formation of a stable porous Zr-P oxide with a surface area as high as 540 m{sup 2}/g.

Liu, P.; Reddy, J.S.; Adnot, A.; Sayari, A. [Univ. Laval, Ste-Foy, Quebec (Canada)

1996-12-31

351

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...

352

Mechanistic Aspects of Pyrite Oxidation in an Oxidizing Gaseous  

E-print Network

Mechanistic Aspects of Pyrite Oxidation in an Oxidizing Gaseous Environment: An in Situ HATR Science, Stony Brook University, Stony Brook, New York 11794-2100 The reaction of FeS2 (pyrite orbital/density functional theory calculations of sulfate-iron hydroxide clusters. Reaction of pyrite

Sparks, Donald L.

353

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

354

21 CFR 172.808 - Copolymer condensates of ethylene oxide and propylene oxide.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Copolymer condensates of ethylene oxide and propylene oxide. 172.808 Section 172.808 Food and Drugs...Additives § 172.808 Copolymer condensates of ethylene oxide and propylene oxide. Copolymer condensates of...

2013-04-01

355

21 CFR 172.808 - Copolymer condensates of ethylene oxide and propylene oxide.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 false Copolymer condensates of ethylene oxide and propylene oxide. 172.808 Section 172.808 Food and Drugs...Additives § 172.808 Copolymer condensates of ethylene oxide and propylene oxide. Copolymer condensates of...

2012-04-01

356

40 CFR 721.10375 - Hydroxypropyl methacrylate, reaction products with propylene oxide and ethylene oxide, copolymer...  

Code of Federal Regulations, 2013 CFR

...Hydroxypropyl methacrylate, reaction products with propylene oxide and ethylene oxide, copolymer with N-vinyl caprolactam (generic...Hydroxypropyl methacrylate, reaction products with propylene oxide and ethylene oxide, copolymer with N-vinyl...

2013-07-01

357

40 CFR 721.10375 - Hydroxypropyl methacrylate, reaction products with propylene oxide and ethylene oxide, copolymer...  

Code of Federal Regulations, 2014 CFR

...Hydroxypropyl methacrylate, reaction products with propylene oxide and ethylene oxide, copolymer with N-vinyl caprolactam (generic...Hydroxypropyl methacrylate, reaction products with propylene oxide and ethylene oxide, copolymer with N-vinyl...

2014-07-01

358

21 CFR 172.808 - Copolymer condensates of ethylene oxide and propylene oxide.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 false Copolymer condensates of ethylene oxide and propylene oxide. 172.808 Section 172.808 Food and Drugs...Additives § 172.808 Copolymer condensates of ethylene oxide and propylene oxide. Copolymer condensates of...

2014-04-01

359

40 CFR 721.10375 - Hydroxypropyl methacrylate, reaction products with propylene oxide and ethylene oxide, copolymer...  

Code of Federal Regulations, 2012 CFR

...Hydroxypropyl methacrylate, reaction products with propylene oxide and ethylene oxide, copolymer with N-vinyl caprolactam (generic...Hydroxypropyl methacrylate, reaction products with propylene oxide and ethylene oxide, copolymer with N-vinyl...

2012-07-01

360

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.

361

Oxidation of nitroxyl anion to nitric oxide by copper ions  

PubMed Central

This study made use of a nitric oxide-sensitive electrode to examine possible means of generating nitric oxide from nitroxyl anion (NO?) released upon the decomposition of Angeli's salt. Our results show that copper ions (from CuSO4) catalyze the rapid and efficient oxidation of nitroxyl to nitric oxide. Indeed, the concentrations of copper required to do so (0.1–100??M) are roughly 100-times lower than those required to generate equivalent amounts of nitric oxide from S-nitroso-N-acetyl-D,L-penicillamine (SNAP). Experiments with ascorbate (1?mM), which reduces Cu2+ ions to Cu+, and with the Cu2+ chelators, EDTA and cuprizone, and the Cu+ chelator, neocuproine, each at 1?mM, suggest that the oxidation is catalyzed by copper ions in both valency states. Some compounds containing other transition metals, i.e. methaemoglobin, ferricytochrome c and Mn(III)TMPyP, were much less efficient than CuSO4 in catalyzing the formation of nitric oxide from nitroxyl, while FeSO4, FeCl3, MnCl2, and ZnSO4 were inactive. Of the copper containing enzymes examined, Cu-Zn superoxide dismutase and ceruloplasmin were weak generators of nitric oxide from nitroxyl, even at concentrations (2500 and 30?u?ml?1, respectively) vastly greater than are present endogenously. Two others, ascorbate oxidase (10?u?ml?1) and tyrosinase (250?u?ml?1) were inactive. Our findings suggest that a copper-containing enzyme may be responsible for the rapid oxidation of nitroxyl to nitric oxide by cells, but the identity of such an enzyme remains elusive. PMID:10991931

Nelli, Silvia; Hillen, Mark; Buyukafsar, Kansu; Martin, William

2000-01-01

362

CATALYTIC DECOMPOSITION OF NITROUS OXIDE  

Microsoft Academic Search

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

Steinberg

1959-01-01

363

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...

364

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

365

Oxidation of Organotrifluoroborates via Oxone®  

PubMed Central

A method for the oxidation of organotrifluoroborates using Oxone® was developed. A variety of aryl-, heteroaryl-, alkenyl-, and alkyltrifluoroborates were converted into the corresponding oxidized products in excellent yields. This method proved to be tolerant of a broad range of functional groups, and in secondary alkyl substrates it was demonstrated to be completely stereospecific. PMID:21192650

Molander, Gary A.; Cavalcanti, Livia N.

2011-01-01

366

Oxidation-resistant nickel alloy  

SciTech Connect

Disclosed is an oxidation resilient nickel alloy containing chromium, tungsten and molybdenum in a critical relationship that provides a combination of engineering properties including a high degree of dynamic oxidation resistance and superior strength. The alloy is especially suited for service under severe conditions, for example, as components of gas turbine engines.

Klarstrom, D.L.

1984-10-09

367

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

368

Detection of nitric oxide pollution  

NASA Technical Reports Server (NTRS)

Studies of absorption spectra enhancement of certain atomic and molecular species inserter in dye-laser cavities have indicated that nitric oxide can be determined at low concentrations. Absorption coefficient of small amounts of nitric oxide in intra-laser-cavity absorption cell containing helium is enhanced by more than two orders of magnitude.

Chackerian, C., Jr.; Weisbach, M. F.

1973-01-01

369

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

370

Segregation beneath oxide scales  

SciTech Connect

Studies are reported and discussed on Auger analyses of the region beneath CrO{sub 3}, Al{sub 2}O{sub 3}, or NiO layers on their metal substrate. Small concentrations of S, C, and P were detected in areas which had been connected to the oxide layer, most probably due to segregation in defects, such as misfit dislocations, microvoids, grain boundaries, etc. For high oxygen pressures at the interface (Ni-NiO) P also can be enriched in the inner layer as phosphate. Sulfur starts to segregate to the free-metal surface as soon as the scale and metal separate, stabilizing voids and accelerating their growth to cavities or favoring the detachment of scale in the case of growth stresses. In this surface segregation S displaces C and P from the metal surface.

Grabke, H.J.; Kurbatov, G.; Schmutzler, H.J. [Max-Planck-Institut fuer Eisenforschung, Duesseldorf (Germany)

1995-02-01

371

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

372

Polymorphism of phosphoric oxide  

USGS Publications Warehouse

The melting points and monotropic relationship of three crystalline forms of phosphoric oxide were determined by the method of quenching. Previous vapor pressure data are discussed and interpreted to establish a pressure-temperature diagram (70 to 600??) for the one-component system. The system involves three triple points, at which solid, liquid and vapor (P4O10) coexist in equilibrium, namely: 420?? and 360 cm., 562?? and 43.7 cm. and 580?? and 55.5 cm., corresponding to the hexagonal, orthorhombic and stable polymorphs, respectively, and at least two distinct liquids, one a stable polymer of the other, which are identified with the melting of the stable form and the hexagonal modification, respectively. Indices of refraction of the polymorphs and glasses were determined. The density and the thermal, hygroscopic and structural properties of the several phases are discussed.

Hill, W.L.; Faust, G.T.; Hendricks, S.B.

1943-01-01

373

Magnetic tunnel junctions with Hf oxide and modified Hf oxide tunnel barriers  

Microsoft Academic Search

Magnetic tunnel junctions (MTJ's) with Hf oxide and modified Hf oxide barriers were fabricated by ozone oxidation. The tunnel magnetoresistance (TMR) ratio in Hf oxide junction was 13% at room temperature and 21% at 77 K. In order to understand the low TMR ratio in MTJ's with Hf oxides compared to those with Al oxides, tunnel barriers were modified by

B. G. Park; T. D. Lee; T. H. Lee; C. G. Kim; C. O. Kim

2003-01-01

374

Advanced oxidation protein products as a novel marker of oxidative stress in uremia  

Microsoft Academic Search

Advanced oxidation protein products as a novel marker of oxidative stress in uremia. Evidence suggests an imbalance between antioxidant and oxidant-generating systems resulting in oxidative stress in uremic patients. As plasma proteins are critical targets for oxidants, we developed a novel spectrophotometric assay which allows to detect advanced oxidation protein products (AOPP) in uremic plasma. By size-exclusion chromatography AOPP are

Véronique Witko-Sarsat; Miriam Friedlander; Chantal Capeillère-Blandin; Thao Nguyen-Khoa; Anh Thu Nguyen; Johanna Zingraff; Paul Jungers; Béatrice Descamps-Latscha

1996-01-01

375

Nitric oxide and pulmonary hypertension  

PubMed Central

Pulmonary hypertension is a serious complication of a number of lung and heart diseases that is characterized by peripheral vascular structural remodeling and loss of vascular tone. Nitric oxide can modulate vascular injury and interrupt elevation of pulmonary vascular resistance selectively; however, it can also produce cytotoxic oxygen radicals and exert cytotoxic and antiplatelet effects. The balance between the protective and adverse effects of nitric oxide is determined by the relative amount of nitric oxide and reactive radicals. Nitric oxide has been shown to be clinically effective in the treatment of congenital heart disease, mitrial valvular disease combined with pulmonary hypertension and in orthotropic cardiac transplantation patients. Additionally, new therapeutic modalities for the treatment of pulmonary hypertension, phosphodiesterase inhibitors, natriuretic peptides and aqueous nitric oxide are also effective for treatment of elevated pulmonary vascular resistance. PMID:20498805

2010-01-01

376

Oxidation and photooxidation of asphalts  

SciTech Connect

Oxidation of asphalt is a major cause of pavement failure owing to hardening of the asphalt binder with accompanying changes in viscosity, separation of components, embrittlement and loss of cohesion and adhesion of the asphalt in the mix. However oxidation of asphalt-aggregate mixes at high temperature is deliberately done to partly harden the mix prior to laydown; hardening then continues during cooling. Excessive hardening at this point is undesirable because of embrittlement and cracking. Slow oxidation of asphalt continues during the service life of the roadbed at a rate that appears to be partly determined by the void volume of the roadbed, as well as the properties of the asphalt and (possibly) the properties of the aggregate. The authors focused their efforts on understanding the mechanistic basis for slow oxidation of asphalt under service conditions in order to predict how rapidly an asphalt will oxidize, based on its composition, and to find better ways to inhibit the process under service conditions.

Mill, T.; Tse, D. (SRI, Menlo Park, CA (United States))

1990-07-01

377

49 CFR 173.337 - Nitric oxide.  

Code of Federal Regulations, 2013 CFR

... 2013-10-01 2013-10-01 false Nitric oxide. 173.337 Section 173.337 Transportation...Preparation and Packaging § 173.337 Nitric oxide. (a) Nitric oxide must be packaged in cylinders conforming to the...

2013-10-01

378

49 CFR 173.337 - Nitric oxide.  

Code of Federal Regulations, 2014 CFR

... 2014-10-01 2014-10-01 false Nitric oxide. 173.337 Section 173.337 Transportation...Preparation and Packaging § 173.337 Nitric oxide. (a) Nitric oxide must be packaged in cylinders conforming to the...

2014-10-01

379

49 CFR 173.337 - Nitric oxide.  

Code of Federal Regulations, 2012 CFR

... 2012-10-01 2012-10-01 false Nitric oxide. 173.337 Section 173.337 Transportation...Preparation and Packaging § 173.337 Nitric oxide. (a) Nitric oxide must be packaged in cylinders conforming to the...

2012-10-01

380

49 CFR 173.337 - Nitric oxide.  

Code of Federal Regulations, 2011 CFR

... 2011-10-01 2011-10-01 false Nitric oxide. 173.337 Section 173.337 Transportation...Preparation and Packaging § 173.337 Nitric oxide. (a) Nitric oxide must be packaged in cylinders conforming to the...

2011-10-01

381

46 CFR 154.1725 - Ethylene oxide.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Ethylene oxide. 154.1725 Section 154.1725 Shipping...Operating Requirements § 154.1725 Ethylene oxide. (a) A vessel carrying ethylene oxide must: (1) Have cargo piping, vent...

2012-10-01

382

46 CFR 154.1725 - Ethylene oxide.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Ethylene oxide. 154.1725 Section 154.1725 Shipping...Operating Requirements § 154.1725 Ethylene oxide. (a) A vessel carrying ethylene oxide must: (1) Have cargo piping, vent...

2010-10-01

383

49 CFR 173.337 - Nitric oxide.  

Code of Federal Regulations, 2010 CFR

... 2010-10-01 2010-10-01 false Nitric oxide. 173.337 Section 173.337 Transportation...Preparation and Packaging § 173.337 Nitric oxide. (a) Nitric oxide must be packaged in cylinders conforming to the...

2010-10-01

384

46 CFR 154.1725 - Ethylene oxide.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Ethylene oxide. 154.1725 Section 154.1725 Shipping...Operating Requirements § 154.1725 Ethylene oxide. (a) A vessel carrying ethylene oxide must: (1) Have cargo piping, vent...

2013-10-01

385

46 CFR 154.1725 - Ethylene oxide.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Ethylene oxide. 154.1725 Section 154.1725 Shipping...Operating Requirements § 154.1725 Ethylene oxide. (a) A vessel carrying ethylene oxide must: (1) Have cargo piping, vent...

2014-10-01

386

46 CFR 154.1725 - Ethylene oxide.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Ethylene oxide. 154.1725 Section 154.1725 Shipping...Operating Requirements § 154.1725 Ethylene oxide. (a) A vessel carrying ethylene oxide must: (1) Have cargo piping, vent...

2011-10-01

387

21 CFR 73.3125 - Iron oxides.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Iron oxides. 73.3125 Section 73.3125...CERTIFICATION Medical Devices § 73.3125 Iron oxides. (a) Identity and specifications. The color additive iron oxides (CAS Reg. No....

2014-04-01

388

21 CFR 73.3125 - Iron oxides.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Iron oxides. 73.3125 Section 73.3125...CERTIFICATION Medical Devices § 73.3125 Iron oxides. (a) Identity and specifications. The color additive iron oxides (CAS Reg. No....

2010-04-01

389

21 CFR 73.3125 - Iron oxides.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Iron oxides. 73.3125 Section 73.3125...CERTIFICATION Medical Devices § 73.3125 Iron oxides. (a) Identity and specifications. The color additive iron oxides (CAS Reg. No....

2011-04-01

390

21 CFR 73.3125 - Iron oxides.  

Code of Federal Regulations, 2013 CFR

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

2013-04-01

391

21 CFR 73.3125 - Iron oxides.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Iron oxides. 73.3125 Section 73.3125...CERTIFICATION Medical Devices § 73.3125 Iron oxides. (a) Identity and specifications. The color additive iron oxides (CAS Reg. No....

2012-04-01

392

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...

393

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

394

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

Microsoft Academic Search

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

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

2006-01-01

395

Catalytic oxidation of chlorobenzene on supported manganese oxide catalysts  

Microsoft Academic Search

Total oxidation of chlorinated aromatics on supported manganese oxide catalysts was investigated. The catalysts have been prepared by wet impregnation method and characterized by XRD and TPR. Among the catalysts with the supports of TiO2, Al2O3 and SiO2, titania-supported catalyst (MnOx\\/TiO2) gives the highest catalytic activity. MnOx\\/TiO2 (Mn loading, 1.9wt.%) shows the total oxidation of chlorobenzene at about 400°C. The

Yan Liu; Mengfei Luo; Zhaobin Wei; Qin Xin; Pinliang Ying

2001-01-01

396

The oxidation of carbon monoxide using tin oxide based catalysts  

NASA Technical Reports Server (NTRS)

The preparation conditions for precious metal/tin oxide catalysts were optimized for maximum carbon monoxide/oxygen recombination efficiency. This was achieved by controlling the tin digestion, the peptization to form the sol, the calcination process and the method of adding the precious metals. Extensive studies of the tin oxide structure were carried out over the temperature range 20 to 500 C in air or hydrogen environments using Raman scattering and X ray diffraction. Adsorbed species on tin oxide, generated in an environment containing carbon monoxide, gave rise to a Raman band at about 1600 cm(exp -1) which was assigned to carbonaceous groups, possible carbonate.

Sampson, Christopher F.; Jorgensen, Norman

1990-01-01

397

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

398

Zinc Oxide Nanostructures by Solvothermal Synthesis .  

E-print Network

??The synthesis, characterization, and properties of three types of one-dimensional zinc oxide nanostructures are described. They were obtained by solvothermal treatment of nanometric zinc oxide… (more)

Segovia, M.

2012-01-01

399

Urinary biomarkers of oxidative status.  

PubMed

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

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

2012-10-01

400

Status of Graphite Oxidation Work  

SciTech Connect

Data were developed to compare the extent of structural damage associated with high temperature exposure to an air leak. Two materials, NBG-18 graphite and unpurified PCEA graphite have been tested as of this report. The scope was limited to isothermal oxidation at a single temperature, 750°C. Ambient post-oxidation compression strength testing was performed for three levels of burn off (1%, 5%, and 10% mass loss) for two leak scenarios: 100% air and 10% air in helium. Temperature, gas flow, and dynamic mass loss oxidation conditions were monitored and recorded for each sample. The oxidation period was controlled with flow of inert gas during the thermal ramp and upon cool down with a constant 10 liter per minute flow maintained throughout furnace operation. Compressive strengths of parallel un-oxidized samples were tested to assess the relative mass loss effects. In addition to baseline samples matching the un-oxidized dimensions of the oxidized samples, two sets of mechanically reduced samples were prepared. One set was trimmed to achieve the desired mass loss by removing an effectively uniform depth from the geometric surface of the sample. The other set was cored to produce a full penetration axial hole down the center of each sample.

Rebecca Smith

2010-05-01

401

Urinary Biomarkers of Oxidative Status  

PubMed Central

Oxidative damage produced by reactive oxygen species (ROS) has been implicated in the etiology and pathology of many health conditions, including a large number of chronic diseases. Urinary biomarkers of oxidative status present a great opportunity to study redox balance in human populations. With urinary biomarkers, specimen collection is non-invasive and the organic/metal content is low, which minimizes the artifactual formation of oxidative damage to molecules in specimens. Also, urinary levels of the biomarkers present intergraded indices of redox balance over a longer period of time compared to blood levels. This review summarizes the criteria for evaluation of biomarkers applicable to epidemiological studies and evaluation of several classes of biomarkers that are formed non-enzymatically: oxidative damage to lipids, proteins, DNA, and allantoin, an oxidative product of uric acid. The review considers formation, metabolism, and exertion of each biomarker, available data on validation in animal and clinical models of oxidative stress, analytical approaches, and their intra- and inter-individual variation. The recommended biomarkers for monitoring oxidative status over time are F2-isoprostanes and 8-oxodG. For inter-individual comparisons, F2-isoprostanes are recommended, whereas urinary 8-oxodG levels may be confounded by differences in the DNA repair capacity. Promising urinary biomarkers include allantoin, acrolein-lysine, and dityrosine. PMID:22683781

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

2012-01-01

402

Oxidant stress suppresses CFTR expression.  

PubMed

Epithelial mucous membranes are repeatedly exposed to oxidants and xenobiotics. CFTR plays a role in glutathione transepithelial flux and in defining the hydration and viscoelasticity of protective mucus. We therefore hypothesized that CFTR expression and function may be modulated by oxidant stress. A sublethal oxidant stress (tert-butylhydroquinone, BHQ) in CFTR-expressing epithelial cells (T84) induced a significant increase in cellular glutathione that was associated with an increase in expression of the gene encoding the heavy subunit of the rate-limiting enzyme for glutathione synthesis, gamma-glutamylcysteine synthetase (gamma-GCShs). CFTR gene expression was markedly decreased according to a time course that mirrored the changes in gamma-GCShs. Western blot analysis confirmed that the decrease in CFTR gene expression was associated with a decrease in CFTR protein. cAMP-dependent iodide efflux was also decreased by the oxidant stress. Nuclear run-on assays indicated that the oxidant stress had no effect on CFTR gene transcription, but the mRNA stability in the oxidant-stressed cells was markedly reduced. Furthermore, BHQ increased gamma-GCShs mRNA while decreasing CFTR mRNA in Calu-3 cells, and taurine chloramine induced similar effects in T84 cells. We conclude that suppression of CFTR expression may represent an adaptive response of mucosal epithelium to an exogenous oxidant stress. PMID:16162662

Cantin, André M; Bilodeau, Ginette; Ouellet, Cristine; Liao, Jie; Hanrahan, John W

2006-01-01

403

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

404

The grazing of Euphausia superba Dana on natural phytoplankton populations  

E-print Network

is placed in a ten milliliter ampoule to which is added water, phosphoric acid and potassium persulfate. The ampoule is bubbled with oxygen, purging all inorganic carbon from the acidified sample. The ampoules were then sealed and baked at 95 C for over... an hour, chemically oxidizing the organic carbon with persulfate. The amount of COz evolved is directly proportional to the original organic carbon content. The COz is vented from the ampoule with a carrier stream of nitrogen gas through a infra...

Meyer, Michael August

2012-06-07

405

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

406

Epitaxial magnetic oxide heterostructures  

NASA Astrophysics Data System (ADS)

Perovskite oxides exhibit a range of physical properties including insulator, semiconductor, metal, superconductor, ferromagnet and many more. Interactions between order parameters result in new properties such as the multiferroic materials. The production of artificial layered epitaxial magnetic heterostructures motivates this research. This requires atomic layer controlled growth which depends on selection of materials for their structural and chemical compatibility, preparation of substrates to achieve well-defined surfaces at the atomic level and the development of a deposition and analysis technique capable of controlling growth' at this level. We have used a pulsed laser deposition system with in situ reflection high-energy electron diffraction to produce epitaxial magnetic oxide heterostructures on lattice-matched substrates and have investigated a number of magnetic interactions. We have demonstrated an unusual antiferromagnetic interfacial exchange coupling between epitaxial bilayers of La0.67Sr0.33MnO 3 and SrRuO3 grown on (001) SrTiO3 substrates. The sign and magnitude of the exchange field depends on the cooling field. By interrupting the charge transfer at the interface with a very thin insulating layer, we have demonstrated this exchange biasing effect is related to the spin-dependent band structures of the materials. We have investigated the structural and magnetic properties of epitaxial multilayers and superlattices of manganites. These materials exhibit colossal magnetoresistance and the Curie temperature can be adjusted over a range of 100 K. We have fabricated La0.67Sr0.33MnO3/La 0.82Ba0.18MnO3 superlattices with layers as thin as 8 unit cells (32A). These superlattices have magnetic transition temperatures above 350 K and coercivities of approximately 10 Oe. Deposition techniques can effectively control the out-of-plane dimension on the nanoscale but control or lateral dimensions has proven more challenging. We have fabricated magnetic perovskite nanodots less than 50 nm tall with diameters less than 100 nm using electron-beam lithography and ion milling. The nanodots maintain their crystallinity, epitaxial structure and ferromagnetic properties. These are the smallest ferromagnetic perovskite nanodots yet reported. This work helps understanding in the issues relating the processing and growth of perovskite heterostructures to physical phenomenon.

Belenky, Land J.

407

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

408

THE FORMATION OF SOLID SOLUTION OXIDES DURING INTERNAL OXIDATION  

SciTech Connect

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

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

1980-09-01

409

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

410

IRON OXIDE NANOPARTICLE-INDUCED OXIDATIVE STRESS AND INFLAMMATION  

EPA Science Inventory

Nanoparticle Physicochemical Characterizations We first focused on creating NP systems that could be used to test our hypotheses and assessing their stability in aqueous media. The iron oxide NP systems were not stable in cell culture medium o...

411

Alumina composites for oxide/oxide fibrous monoliths  

SciTech Connect

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

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

2000-03-01

412

Study of zinc oxide ceramics  

SciTech Connect

The authors determined the elemental and phase composition of zinc oxide ceramic (ZOC) by emission spectral (ESA), x-ray phase (XPA), and micro x-ray spectral (MXSA) analysis as well as by the method of electron spectroscopy for chemical analysis (ESCA). They studied the microstructure on metallographic and scanning electron microscopes using MXSA and ESCA data. Samples of ZOC were synthesized in the system of oxides Zn, Bi, Sb, Co, Mn, Sn, Si, Ni, Mg, Cr and B. The authors found that several mechanisms are responsible for the changes in the parameters of varistors based on zinc oxide ceramic, each of whose contribution depends on the operating conditions of the varistor.

Petvkhov, A.P.; Fedotova, O.I.; Rumyantseva, I.A.; Teslenko, S.P.

1986-01-01

413

Room Temperature Chemical Oxidation of Delafossite-Type Oxides  

Microsoft Academic Search

Examination of the delafossite-type structure of CuLaO2 and CuYO2 suggests that there is room enough to accomodate intercalated oxide ions and the charge compensation resulting simply from the oxidation of an equivalent amount of Cu+ into Cu2+. Reaction with hypohalites in an aqueous solution leads to color change. Evidence of the formation of Cu2+ is given by TGA, iodometric titration,

M. Trari; J. Toepfer; J. P. Doumerc; M. Pouchard; A. Ammar; P. Hagenmuller

1994-01-01

414

Tryptophan oxidation in proteins exposed to thiocyanate-derived oxidants.  

PubMed

Human defensive peroxidases, including lactoperoxidase (LPO) and myeloperoxidase (MPO), are capable of catalyzing the oxidation of halides (X(-)) by H2O2 to give hypohalous acids (HOX) for the purpose of cellular defense. Substrate selectivity depends upon the relative abundance of the halides, but the pseudo-halide thiocyanate (SCN(-)) is a major substrate, and sometimes the exclusive substrate, of all defensive peroxidases in most physiologic fluids. The resulting hypothiocyanous acid (HOSCN) has been implicated in cellular damage via thiol oxidation. While thiols are believed to be the primary target of HOSCN in vivo, Trp residues have also been implicated as targets for HOSCN. However, the mechanism involved in HOSCN-mediated Trp oxidation was not established. Trp residues in proteins appeared to be susceptible to oxidation by HOSCN, whereas free Trp and Trp residues in small peptides were found to be unreactive. We show that HOSCN-induced Trp oxidation is dependent on pH, with oxidation of free Trp, and Trp-containing peptides observed when the pH is below 2. These conditions mimic those employed previously to precipitate proteins after treatment with HOSCN, which accounts for the discrepancy in the results reported for proteins versus free Trp and small peptides. The reactant in these cases may be thiocyanogen ((SCN)2), which is produced by comproportionation of HOSCN and SCN(-) at low pH. Reaction of thiocyanate-derived oxidants with protein Trp residues at low pH results in the formation of a number of oxidation products, including mono- and di-oxygenated derivatives, which are also formed with other hypohalous acids. Our data suggest that significant modification of Trp by HOSCN in vivo is likely to have limited biological relevance. PMID:25172223

Bonifay, Vincent; Barrett, Tessa J; Pattison, David I; Davies, Michael J; Hawkins, Clare L; Ashby, Michael T

2014-12-15

415

Direct comparison of the electrical properties in metal\\/oxide\\/nitride\\/oxide\\/silicon and metal\\/aluminum oxide\\/nitride\\/oxide\\/silicon capacitors with equivalent oxide thicknesses  

Microsoft Academic Search

We examine the electrical properties of metal\\/oxide\\/nitride\\/oxide\\/silicon (MONOS) capacitors with two different blocking oxides, SiO2 and Al2O3, under the influence of the same electric field. The thickness of the Al2O3 layer is set to 150 Å, which is electrically equivalent to a thickness of the SiO2 layer of 65 Å, in the MONOS structure for this purpose. The capacitor with the Al2O3

Ho-Myoung An; Yu Jeong Seo; Hee Dong Kim; Kyoung Chan Kim; Jong-Guk Kim; Won-Ju Cho; Jung-Hyuk Koh; Yun Mo Sung; Tae Geun Kim

2009-01-01

416

Chemiluminescence of nitric oxide  

NASA Technical Reports Server (NTRS)

Measurements of the intensities of the delta and gamma bands of nitric oxide in the nighttime terrestrial thermosphere are presented and used to infer the rate coefficient for the transition from the C 2 Pi to the A 2 Sigma + states. The nightglow spectrum was observed between 1900 and 2300 A at a resolution of 15 A by a rocket-borne scanning 1/4-m spectrometer pointing north at an apogee of 150 km. Progressions of the delta, gamma and epsilon bands are identified on the spectra by the construction of synthetic spectra, and the contributions of resonance fluorescence to the total band intensities are calculated. Finally, the ratio of the sum of the gamma bands for v-prime = 0 to the sum of the delta bands for v-prime = 0 is used to derive a branching ratio of 0.21 + or - 0.04 to the A 2 Sigma + state, which yields a probability for the C-A transition of 5.6 + or - 1.5 x to the 6th/sec.

Sharp, W. E.; Rusch, D. W.

1981-01-01

417

Alkali oxide-tantalum, niobium and antimony oxide ionic conductors  

NASA Technical Reports Server (NTRS)

The phase equilibrium relations of four systems were investigated in detail. These consisted of sodium and potassium antimonates with antimony oxide and tantalum and niobium oxide with rubidium oxide as far as the ratio 4Rb2O:llB2O5 (B=Nb, Ta). The ternary system NaSbO3-Sb2O4-NaF was investigated extensively to determine the actual composition of the body centered cubic sodium antimonate. Various other binary and ternary oxide systems involving alkali oxides were examined in lesser detail. The phases synthesized were screened by ion exchange methods to determine mobility of the mobility of the alkali ion within the niobium, tantalum or antimony oxide (fluoride) structural framework. Five structure types warranted further investigation; these structure types are (1) hexagonal tungsten bronze (HTB), (2) pyrochlore, (3) the hybrid HTB-pyrochlore hexagonal ordered phases, (4) body centered cubic antimonates and (5) 2K2O:3Nb2O5. Although all of these phases exhibit good ion exchange properties only the pyrochlore was prepared with Na(+) ions as an equilibrium phase and as a low porosity ceramic. Sb(+3) in the channel interferes with ionic conductivity in this case, although relatively good ionic conductivity was found for the metastable Na(+) ion exchanged analogs of RbTa2O5F and KTaWO6 pyrochlore phases.

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

1975-01-01

418

Nanostructured anodic iron oxide film as photoanode for water oxidation  

NASA Astrophysics Data System (ADS)

Two different configurations of photoanodes based on anodic iron oxide were investigated for photoelectrochemical water oxidation. A self-ordered and vertically oriented array of iron oxide nanotubes was obtained by anodization of pure iron substrate in an ethylene glycol based electrolyte containing 0.1M NH4F + 3 vol% water (EGWF solution) at 50 V for 15 min. Annealing of the oxide nanotubes in a hydrogen environment at 500 °C for 1 h resulted in a predominantly hematite phase. The second type of photoanode was obtained by a two-step anodization procedure. This process resulted in a two-layered oxide structure, a top layer of nano-dendrite morphology and a bottom layer of nanoporous morphology. This electrode configuration combined the better photocatalytic properties of the nano-dendritic iron oxide and better electron transportation behaviour of vertically oriented nano-channels. Annealing of these double anodized samples in an acetylene environment at 550 °C for 10 min resulted in a mixture of maghemite and hematite phases. Photocurrent densities of 0.74 mA cm-2 at 0.2 VAg/AgCl and 1.8 mA cm-2 at 0.5 VAg/AgCl were obtained under AM 1.5 illumination in 1M KOH solution. The double anodized samples showed high photoconductivity and more negative flat band potential (-0.8 VAg/AgCl), which are the properties required for promising photoanode materials.

Rangaraju, R. R.; Panday, A.; Raja, K. S.; Misra, M.

2009-07-01

419

COPD: balancing oxidants and antioxidants  

PubMed Central

Chronic obstructive pulmonary disease (COPD) is one of the most common chronic illnesses in the world. The disease encompasses emphysema, chronic bronchitis, and small airway obstruction and can be caused by environmental exposures, primarily cigarette smoking. Since only a small subset of smokers develop COPD, it is believed that host factors interact with the environment to increase the propensity to develop disease. The major pathogenic factors causing disease include infection and inflammation, protease and antiprotease imbalance, and oxidative stress overwhelming antioxidant defenses. In this review, we will discuss the major environmental and host sources for oxidative stress; discuss how oxidative stress regulates chronic bronchitis; review the latest information on genetic predisposition to COPD, specifically focusing on oxidant/antioxidant imbalance; and review future antioxidant therapeutic options for COPD. The complexity of COPD will necessitate a multi-target therapeutic approach. It is likely that antioxidant supplementation and dietary antioxidants will have a place in these future combination therapies. PMID:25673984

Fischer, Bernard M; Voynow, Judith A; Ghio, Andrew J

2015-01-01

420

Oxidation-responsive polymeric vesicles  

NASA Astrophysics Data System (ADS)

Vesicles formed in water by synthetic macro-amphiphiles have attracted much attention as nanocontainers having properties that extend the physical and chemical limits of liposomes. We sought to develop ABA block copolymeric amphiphiles that self-assemble into unilamellar vesicles that can be further oxidatively destabilized. We selected poly(ethylene glycol) (PEG) as the hydrophilic A blocks, owing to its resistance to protein adsorption and low toxicity. As hydrophobic B blocks, we selected poly(propylene sulphide) (PPS), owing to its extreme hydrophobicity, its low glass-transition temperature, and most importantly its oxidative conversion from a hydrophobe to a hydrophile, poly(propylene sulphoxide) and ultimately poly(propylene sulphone). This is the first example of the use of oxidative conversions to destabilize such carriers. This new class of oxidation-responsive polymeric vesicles may find applications as nanocontainers in drug delivery, biosensing and biodetection.

Napoli, Alessandro; Valentini, Massimiliano; Tirelli, Nicola; Müller, Martin; Hubbell, Jeffrey A.

2004-03-01

421

Nitric Oxide-Releasing Compounds  

NSDL National Science Digital Library

The five WebWare Molecules for December derive from the article Nitrogen-Based Diazeniumdiolates: Versatile Nitric Oxide-Releasing Compounds for Biomedical Research and Potential Clinical Applications by Joseph E. Saavedra and Larry K. Keefer.

422

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

423

Peroxynitrite, a Stealthy Biological Oxidant*  

PubMed Central

Peroxynitrite is the product of the diffusion-controlled reaction of nitric oxide and superoxide radicals. Peroxynitrite, a reactive short-lived peroxide with a pKa of 6.8, is a good oxidant and nucleophile. It also yields secondary free radical intermediates such as nitrogen dioxide and carbonate radicals. Much of nitric oxide- and superoxide-dependent cytotoxicity resides on peroxynitrite, which affects mitochondrial function and triggers cell death via oxidation and nitration reactions. Peroxynitrite is an endogenous toxicant but is also a cytotoxic effector against invading pathogens. The biological chemistry of peroxynitrite is modulated by endogenous antioxidant mechanisms and neutralized by synthetic compounds with peroxynitrite-scavenging capacity. PMID:23861390

Radi, Rafael

2013-01-01

424

Oxidation of Amines by Flavoproteins  

PubMed Central

Many flavoproteins catalyze the oxidation of primary and secondary amines, with the transfer of a hydride equivalent from a carbon -nitrogen bond to the flavin cofactor. Most of these amine oxidases can be classified into two structural families, the D -amino acid oxidase/sarcosine oxidase family and the monoamine oxidase family. This review discusses the present understanding of the mechanisms of amine and amino acid oxidation by flavoproteins, focusing on these two structural families. PMID:19651103

Fitzpatrick, Paul F.

2009-01-01

425

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

426

Thermal oxidation of carbon nanomaterials  

NASA Astrophysics Data System (ADS)

The process of the thermal oxidation of various carbon nanomaterials (multiwalled carbon nanotubes, carbon black, nanoporous carbon and graphite) used in the catalytic layers of electrochemical energy converters (electrolyzers, fuel cells) has been studied. The thermal stability of these materials has been determined. Relationships between the structural characteristics of carbon nanomaterials and the parameters of their thermal oxidation in air have determined using the methods of differential thermal analysis and adsorption-structure analysis.

Glebova, N. V.; Nechitailov, A. A.; Kukushkina, Yu. A.; Sokolov, V. V.

2011-05-01

427

Electrochemical oxidation of chlorinated phenols  

SciTech Connect

Electrochemical oxidation has been proposed as a remediation method for chlorinated phenols but is hampered by anode fouling. In this work the authors explore the mechanism of anode fouling by chlorinated phenols, compare structure vs reactivity for phenols differing in the extent of chlorination, and relate the efficiency of oxidation to the mechanism of oxidation at different electrode types. Linear sweep voltammograms at a Pt anode at several concentrations, sweep rates, and pH were interpreted in terms of deposition of oligomers on the anode surface. Chronopotentiometry at Pt showed that the oxidation potentials of the chlorinated phenol congeners ranged from +0.6 to +1.3 V vs SHE in the pH range 2--12; four electrons are transferred for mono- and trichlorophenols and two for pentachlorophenol. Passivation increased in parallel with the uncompensated resistance of the solution and occurred only at potentials at which water is oxidized, suggesting that the formation of the oligomer film involves attack of hydroxyl radicals on electrochemically oxidized substrate. Seven chlorinated phenols were electrolyzed at PbO{sub 2}, SnO{sub 2}, and IrO{sub 2} anodes. Relative reactivities of congeners were anode-dependent, due to different mechanisms of oxidation: direct electron-transfer oxidation at PbO{sub 2} and hydroxyl radical attack at SnO{sub 2} and IrO{sub 2} At current densities <0.1 mA cm{sup {minus}2}, current efficiencies >50% could be achieved with 4-chlorophenol at all three anodes.

Rodgers, J.D.; Jedral, W.; Bunce, N.J. [Univ. of Guelph, Ontario (Canada). Dept. of Chemistry and Biochemistry] [Univ. of Guelph, Ontario (Canada). Dept. of Chemistry and Biochemistry

1999-05-01

428

Oxidation and sulfonation of cellulosics  

Microsoft Academic Search

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

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

2008-01-01

429

Accelerated oxidation processes is biodiesel  

SciTech Connect

Biodiesel is an alternative fuel for diesel engines that can be produced from renewable feedstocks such as vegetable oil and animal fats. These feedstocks are reacted with an alcohol to produce alkyl monoesters that can be used in conventional diesel engines with little or no modification. Biodiesel, especially if produced from highly unsaturated oils, oxidizes more rapidly than diesel fuel. This article reports the results of experiments to track the chemical and physical changes that occur in biodiesel as it oxidizes. These results show the impact of time, oxygen flow rate, temperature, metals, and feedstock type on the rate of oxidation. Blending with diesel fuel and the addition of antioxidants are explored also. The data indicate that without antioxidants, biodiesel will oxidize very quickly at temperatures typical of diesel engines. This oxidation results in increases in peroxide value, acid value, and viscosity. While the peroxide value generally reaches a plateau of about 350 meq/kg ester, the acid value and viscosity increase monotonically as oxidation proceeds.

Canakci, M.; Monyem, A.; Van Gerpen, J.

1999-12-01

430

Oxidative stress and hypertension.  

PubMed

This review has summarized some of the data supporting a role of ROS and oxidant stress in the genesis of hypertension. There is evidence that hypertensive stimuli, such as high salt and angiotensin II, promote the production of ROS in the brain, the kidney, and the vasculature and that each of these sites contributes either to hypertension or to the untoward sequelae of this disease. Although the NADPH oxidase in these various organs is a predominant source, other enzymes likely contribute to ROS production and signaling in these tissues. A major clinical challenge is that the routinely used antioxidants are ineffective in preventing or treating cardiovascular disease and hypertension. This is likely because these drugs are either ineffective or act in a non-targeted fashion, such that they remove not only injurious ROS Fig. 5. Proposed role of T cells in the genesis of hypertension and the role of the NADPH oxidase in multiple cells/organs in modulating this effect. In this scenario, angiotensin II stimulates an NADPH oxidase in the CVOs of the brain, increasing sympathetic outflow. Sympathetic nerve terminals in lymph nodes activate T cells, and angiotensin II also directly activates T cells. These stimuli also activate expression of homing signals in the vessel and likely the kidney, which attract T cells to these organs. T cells release cytokines that stimulate the vessel and kidney NADPH oxidases, promoting vasoconstriction and sodium retention. SFO, subfornical organ. 630 Harrison & Gongora but also those involved in normal cell signaling. A potentially important and relatively new direction is the concept that inflammatory cells such as T cells contribute to hypertension. Future studies are needed to understand the interaction of T cells with the CNS, the kidney, and the vasculature and how this might be interrupted to provide therapeutic benefit. PMID:19427495

Harrison, David G; Gongora, Maria Carolina

2009-05-01

431

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

432

Pretreatment for reducing oxidative reactivity of baseoils  

Microsoft Academic Search

This patent describes a method of producing lubricating oil baseoil having a reduced coking tendency. It comprises: subjecting the baseoil to conditions which accelerate formation of asphaltene coking precursors in the baseoil. The conditions comprising oxidizing the baseoil by sparging the baseoil with an oxidizing gas selected from the group consisting of air, oxygen; ozone, nitrogen oxides, sulfur oxides, and

Dickakian

1989-01-01

433

Three-Dimensional Tungsten Oxide Nanowire Networks**  

E-print Network

Three-Dimensional Tungsten Oxide Nanowire Networks** By Jun Zhou, Yong Ding, Shao Z. Deng, Li Gong, Ning S. Xu,* and Zhong L. Wang* Among transition metal oxides, tungsten oxides (WO3±d)are of great.[1±6] With outstanding electrochromic, optochromic, and gaschromic properties, tungsten oxides have

Wang, Zhong L.

434

REVERSIBLE SOLID OXIDE CELLS Mogens Mogensen1  

E-print Network

1 REVERSIBLE SOLID OXIDE CELLS Mogens Mogensen1 , Søren Højgaard Jensen1,2 , Anne Hauch1,3 , Ib The reversibility of solid oxide fuel cells (SOFC), i.e. that they could also work in the solid oxide electrolyser interest in the solid oxide cells (SOC) as electrolyser. During the time since the work of Isenberg

435

The oxidation of metals and alloys  

NASA Technical Reports Server (NTRS)

This paper reviews the various types of oxidation processes occurring with pure metals and gives explanations for the varying time-temperature-oxidation rate relations that exist for copper, tungsten, zinc, cadmium, and tantalum. The effect of shape and crystal structure on oxidation is discussed. Principles derived are applied to the oxidation of alloys.

Scheil, Erich

1952-01-01

436

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

437

New strategies for electrodepositing yttrium oxide  

Microsoft Academic Search

This dissertation describes new strategies to electrodeposit yttrium oxide in non-aqueous media. Yttrium oxide is widely used as a phosphor host material in display devices. Electrodeposition of yttrium oxide is achieved by two methods in this study: (1) by electrogenerating a base at the cathode, and (2) by electrochemically transferring oxide equivalents to a metal center. The electrochemical method used

Vishnu V. Rajasekharan

2005-01-01

438

Interactions of pentachlorophenol with manganese oxide  

SciTech Connect

Abiotic interactions of pentachlorophenol (PCP) on manganese oxide surfaces were investigated to determine the extent of transformation. The optimal pH and ratio of manganese oxide to PCP were determined. Sorption of PCP on manganese oxide surfaces was quantified at optimal conditions. The effectiveness of utilizing manganese oxide to remediate contaminated subsurface environments was investigated.

Cramer, A.; McLean, J.E.; Sims, R.C. [Utah State Univ., Logan, UT (United States). Utah Water Research Lab.

1994-12-31

439

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

440

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

NASA Astrophysics Data System (ADS)

Leptothrix discophora SS-1 excretes at least one Mn 2+-oxidizing protein that, in association with acidic exopolymers, catalyzes a rapid oxidation of Mn 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 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, Lee F.; Ghiorse, William C.

1988-08-01

441

Depth distribution of ammonia oxidation rates and ammonia-oxidizer community composition in the Sargasso Sea  

E-print Network

Depth distribution of ammonia oxidation rates and ammonia-oxidizer community composition University, Princeton, New Jersey Abstract Ammonia oxidation rates and ammonia-oxidizer community structure in December 2009. Ammonia oxidation rates, measured from trace additions of 15NHz 4 (12­18 nmol L21), ranged

Ward, Bess

442

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

Microsoft Academic Search

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

O. Simond; V. Schaller; Ch. Comninellis

1997-01-01

443

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

444

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

445

Radiation-induced cationic polymerization of limonene oxide,. cap alpha. -pinene oxide, and. beta. -pinene oxide  

SciTech Connect

After suitable drying, the subject monomers in the form of neat liquids undergo radiation-induced polymerization with no apparent side reactions and high conversions to precipitatable polymers of low molecular weight. A cationic mechanism is evidenced by the strongly retarding effect of tri-n-propylamine on the polymerization rate. At 25/sup 0/C, limonene oxide gives the highest polymerization rates, an average conversion of 36% per Mrad being obtained in comparison with values of 5.7 and 7.3% per Mrad for the ..cap alpha..-pinene and ..beta..-pinene oxides, respectively. Similarly, the average anti DP/sub n/ decreases from 11.8 for the limonene oxide polymer to 5.6 and 4.0 for the ..cap alpha..-pinene oxide and ..beta..-pinene oxide polymers, respectively. A high frequency of chain transfer to monomer is indicated in each case by the fact that the kinetic chain lengths are estimated to be on the order of a hundred times larger than the anti DP/sub n/ values. Structural characterization of the limonene oxide polymer by /sup 1/H and /sup 13/C NMR spectroscopy provides conclusive evidence that the polymerization proceeds by the opening of the epoxide ring to yield a 1,2-trans polyether. Similar NMR studies on the polymers formed from the ..cap alpha..-pinene and ..beta..-pinene oxides show that in the polymerization of these monomers, the opening of the epoxide ring is generally accompanied by the concomitant ring opening of the cyclobutane ring structure to yield a gem-dimethyl group in the main chain. The detection of isopropenyl end groups in the pinene oxide polymers is also consistent with this mode of propagation being followed by chain (proton) transfer to monomer.

Aikins, J.A.; Williams, F.

1984-01-01

446

Nitrous oxide production and methane oxidation by different ammonia-oxidizing bacteria  

Microsoft Academic Search

Ammonia-oxidizing bacteria (AOB) are thought to contribute significantly to NâO production and methane oxidation in soils. Most knowledge derives from experiments with Nitrosomonas europaea, which appears to be of minor importance in most soils compared to Nitrosospira spp. The authors have conducted a comparative study of levels of aerobic NâO production in six phylogenetically different Nitrosospira strains newly isolated from

QING-QIAO JIANG; LARS R. BAKKEN

1999-01-01

447

Transparent conducting oxides and production thereof  

SciTech Connect

Transparent conducting oxides and production thereof are disclosed. An exemplary method of producing a transparent conducting oxide (TCO) material may comprise: providing a TCO target doped with either a high-permittivity oxide or a low-permittivity oxide in a process chamber. The method may also comprise depositing a metal oxide on the target in the process chamber to form a thin film having enhanced optical properties without substantially decreasing electrical quality.

Gessert, Timothy A.; Yoshida, Yuki; Coutts, Timothy J.

2014-06-10

448

Transparent conducting oxides and production thereof  

SciTech Connect

Transparent conducting oxides and production thereof are disclosed. An exemplary method of producing a transparent conducting oxide (TCO) material may comprise: providing a TCO target (110) doped with either a high-permittivity oxide or a low-permittivity oxide in a process chamber (100). The method may also comprise depositing a metal oxide on the target (110) to form a thin film having enhanced optical properties without substantially decreasing electrical quality.

Gessert, Timothy A; Yoshida, Yuki; Coutts, Timothy J

2014-05-27

449

Method for plating with metal oxides  

SciTech Connect

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

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

1994-08-23

450

Detecting oxidized contaminants in water using sulfur-oxidizing bacteria.  

PubMed

For the rapid and reliable detection of oxidized contaminants (i.e., nitrite, nitrate, perchlorate, dichromate) in water, a novel toxicity detection methodology based on sulfur-oxidizing bacteria (SOB) has been developed. The methodology exploits the ability of SOB to oxidize elemental sulfur to sulfuric acid in the presence of oxygen. The reaction results in an increase in electrical conductivity (EC) and a decrease in pH. When oxidized contaminants were added to the system, the effluent EC decreased and the pH increased due to the inhibition of the SOB. We found that the system can detect these contaminants in the 5-50 ppb range (in the case of NO(3)(-), 10 ppm was detected), which is lower than many whole-cell biosensors to date. At low pH, the oxidized contaminants are mostly in their acid or nonpolar, protonated form which act as uncouplers and make the SOB biosensor more sensitive than other whole-cell biosensors which operate at higher pH values where the contaminants exist as dissociated anions. The SOB biosensor can detect toxicity on the order of minutes to hours which can serve as an early warning so as to not pollute the environment and affect public health. PMID:21417357

Van Ginkel, Steven W; Hassan, Sedky H A; Ok, Yong Sik; Yang, Jae E; Kim, Yong-Seong; Oh, Sang-Eun

2011-04-15

451

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

452

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

SciTech Connect

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

Lad, R.J.

1992-01-01

453

Nitrous oxide production and methane oxidation by different ammonia-oxidizing bacteria  

SciTech Connect

Ammonia-oxidizing bacteria (AOB) are thought to contribute significantly to N{sub 2}O production and methane oxidation in soils. Most knowledge derives from experiments with Nitrosomonas europaea, which appears to be of minor importance in most soils compared to Nitrosospira spp. The authors have conducted a comparative study of levels of aerobic N{sub 2}O production in six phylogenetically different Nitrosospira strains newly isolated from soils and in two N. europaea and Nitrosospira multiformis type strains. The fraction of oxidized ammonium released as N{sub 2}O during aerobic growth was remarkably constant for all the Nitrosospira strains, irrespective of the substrate supply (urea versus ammonium), the pH, or substrate limitation. N. europaea and Nitrosospira multiformis released similar fractions of N{sub 2}O when they were supplied with ample amounts of substrates, but the fractions rose sharply when they were restricted by a low pH or substrate limitation. Phosphate buffer doubled the N{sub 2}O release for all types of AOB. No detectable oxidation of atmospheric methane was detected. Calculations based on detection limits as well as data in the literature on CH{sub 4} oxidation by AOB bacteria prove that none of the tested strains contribute significantly to the oxidation of atmospheric CH{sub 4} in soils.

Jiang, Q.Q.; Bakken, L.R. [Agricultural Univ. of Norway, Aas (Norway)

1999-06-01

454

Microbial Formation of Manganese Oxides  

PubMed Central

Microbial manganese oxidation was demonstrated at high Mn2+ concentrations (5 g/liter) in bacterial cultures in the presence of a microalga. The structure of the oxide produced varied depending on the bacterial strain and mode of culture. A nonaxenic, acid-tolerant microalga, a Chlamydomonas sp., was found to mediate formation of manganite (?-MnOOH). Bacteria isolated from associations with crude cultures of this alga grown in aerated bioreactors formed disordered ?-MnO2 from Mn2+ at concentrations of 5 g/liter over 1 month, yielding 3.3 g of a semipure oxide per liter. All algal-bacterial cultures removed Mn2+ from solution, but only those with the highest removal rates formed an insoluble oxide. While the alga was an essential component of the reaction, a Pseudomonas sp. was found to be primarily responsible for the formation of a manganese precipitate. Medium components—algal biomass and urea—showed optima at 5.7 and 10 g/liters, respectively. The scaled-up culture (50 times) gave a yield of 22.3 g (53 mg/liter/day from a 15-liter culture) of semipure disordered ?-MnO2, identified by X-ray diffraction and Fourier transform infrared (FTIR) spectroscopy, and had a manganese oxide O/Mn ratio of 1.92. The Mn(IV) content in the oxide was low (30.5%) compared with that of mined or chemically formed ?-MnO2 (ca. 50%). The shortfall in the bacterial oxide manganese content was due to biological and inorganic contaminants. FTIR spectroscopy, transmission electron microscopy, and electron diffraction studies have identified manganite as a likely intermediate product in the formation of disordered ?-MnO2. PMID:16348459

Greene, Anthony C.; Madgwick, John C.

1991-01-01

455

Flame generation of ceramic oxides  

SciTech Connect

Large quantities of TiO{sub 2}, SiO{sub 2}, and mixed TiO{sub 2}-SiO{sub 2} powders are produced annually by combustion of their chloride precursors for use as catalysts and as paint opacifiers. We have studied the formation of flame synthesized oxides using a counterflow diffusion flame burner. It has enabled us to obtain desired morphologies and crystalline structures by varying process variables such as flame temperature and precursor concentration ratio, and by selecting the appropriate feed stream. For example, over the ranges of TiCl{sub 4} (the TiO{sub 2} precursor) concentrations tested, feeding it only into the oxidizer stream yields mainly anatase TiO{sub 2} powders, while feeding only into the fuel stream yields mainly rutile TiO{sub 2} powders. By adding TiCl{sub 4} and SiCl{sub 4} simultaneously to the same flame and choosing conditions such that the TiO{sub 2} condenses before the SiO{sub 2}, we obtained SiO{sub 2} attached to, or coated onto, TiO{sub 2} particles in a single step process. Oxide particles produced in the counterflow diffusion flame burner are in the 10 to 100 manometer range. Their high surface area makes them potentially useful as catalysts. V{sub 2}O{sub 5}-TiO{sub 2} and V{sub 2}O{sub 5}-Al{sub 2}O{sub 3} are well-known catalysts for the selective oxidation of o-xylene to phthalic anhydride, and V-P-O oxides are widely used catalysts for the selective oxidation of butene and n-butane to maleic anhydride. Several V{sub 2}O{sub 5}-based mixed oxide powders were produced in the burner. 21 refs.

Katz, J.L. [John Hopkins Univ., Baltimore, MD (United States)

1996-12-31

456

Oxidation of Octopus vulgaris hemocyanin by nitrogen oxides  

SciTech Connect

The reaction of Octopus vulgaris hemocyanin with nitrite was studied under a variety of conditions in which the green half-met derivative is formed. Analytical evidence shows that the amount of chemically detectable nitrite in various samples of the derivative is not proportional to the cupric copper detected by EPR. The kinetics of oxidation of hemocyanin as a function of protein concentration and pH, in the presence of nitrite and ascorbate, is consistent with a scheme in which NO/sub 2/ is the reactive oxidant. We suggest that the green half-methemocyanin contains a metal center with one cuprous and one cupric copper without an exogenous nitrogen oxide ligand.

Salvato, B.; Giacometti, G.M.; Beltramini, M.; Zilio, F.; Giacometti, G.; Magliozzo, R.S.; Peisach, J.

1989-01-24

457

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

458

A Study of Oxides for Solid Oxide Cells  

NASA Astrophysics Data System (ADS)

As the world energy consumption increases, it is a question of global health to increase energy production efficiency and to reduce CO2 emissions. In that respect, solid oxide cells are solid state devices that convert directly fuel into electricity, or vice versa. In fact, when run in fuel cell mode, such devices produce electricity with efficiency up to twice that of current natural gas power plants. However, systems equipped with them have only seen limited commercialization owing to issues of cost, durability, and performance. In this thesis, three different aspects of solid oxide cells are studied. First, the effects of stress on the properties of mixed ionic electronic conducting oxides are considered. Such oxides can be used as electrode materials, where they are often subject to large stresses, which can, in turn, affect their performance. Hence, understanding the relationship between stress and properties in such materials is crucial. Non-stoichiometry in strontium substituted lanthanum cobaltite is found to increase under tension and to decrease under compression. Then, degradation taking place when the cell is run in electrolysis mode is discussed. A high current allows for a high production rate of hydrogen gas. However, this can also lead to oxygen bubble nucleating in the electrolyte and subsequent degradation of the cell. The analysis conducted here shows that such nucleation phenomenon can be avoided by keeping the overpotential at the oxygen electrode below a critical value. Finally, the growth and coarsening of catalyst nanoparticles at the surface of an oxide is studied. Scientists have developed new oxides for anodes in which a catalyst material is dissolved and exsolves under operating conditions. As the performance of the cell is controlled by the surface area of the catalyst phase, understanding the kinetics of the growth is critical to predict the performance of the cell. An approach is developed to study the growth of one particle, in the limiting case where only bulk transport is allowed.

Comets, Olivier

459

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

460

Sulfite Oxidation in Chlorobaculum Tepidum  

PubMed Central

The green sulfur bacterium Chlorobaculum tepidum is proposed to oxidize sulfide and elemental sulfur via sulfite as an obligate intermediate. The sulfite pool is predicted to be contained in the cytoplasm and be oxidized by the concerted action of ApsBA, which directly oxidizes sulfite, and QmoABC, which transfers electrons from ApsBA to the quinone pool. Like other green sulfur bacteria, C. tepidum was unable to use exogenously provided sulfite as the sole electron donor. However, exogenous sulfite significantly stimulated the growth yield of sulfide limited batch cultures. The growth of C. tepidum mutant strains, CT0867/qmoB::TnOGm and CT0868/qmoC::TnOGm, was not increased by sulfite. Furthermore, these strains accumulated sulfite and displayed a growth yield decrease when grown on sulfide as the sole electron donor. These results support an obligate, cytoplasmic sulfite intermediate as part of the canonical sulfur oxidation pathway in C. tepidum that requires the Qmo complex for oxidation. PMID:21747809

Rodriguez, Jesse; Hiras, Jennifer; Hanson, Thomas E.

2011-01-01

461

Oxidation of low cobalt alloys  

NASA Technical Reports Server (NTRS)

Four high temperature alloys: U-700, Mar M-247, Waspaloy and PM/HIP U-700 were modified with various cobalt levels ranging from 0 percent to their nominal commercial levels. The alloys were then tested in cyclic oxidation in static air at temperatures ranging from 1000 to 1150 C at times from 500 to 100 1 hour cycles. Specific weight change with time and X-ray diffraction analyses of the oxidized samples were used to evaluate the alloys. The alloys tend to be either Al2O3/aluminate spinel or Cr2O3/chromite spinel formers depending on the Cr/Al ratio in the alloy. Waspaloy with a ratio of 15:1 is a strong Cr2O3 former while this U-700 with a ratio of 3.33:1 tends to form mostly Cr2O3 while Mar M-247 with a ratio of 1.53:1 is a strong Al2O3 former. The best cyclic oxidation resistance is associated with the Al2O3 formers. The cobalt levels appear to have little effect on the oxidation resistance of the Al2O3/aluminate spinel formers while any tendency to form Cr2O3 is accelerated with increased cobalt levels and leads to increased oxidation attack.

Barrett, C. A.

1982-01-01

462

Electronic structure of graphene oxide and reduced graphene oxide monolayers  

NASA Astrophysics Data System (ADS)

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-? electrons (˜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 (?+?) electrons as obtained from energy loss spectra was found to increase by ˜28% on reduction of GO.

Sutar, D. S.; Singh, Gulbagh; Divakar Botcha, V.

2012-09-01

463

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...

464

Volatilization of oxides during oxidation of some superalloys at 1200 C  

NASA Technical Reports Server (NTRS)

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 except GE-1541, chromium was found to be the main metallic element in the oxide scales.

Zaplatynsky, I.

1977-01-01

465