Science.gov

Sample records for enhanced permanganate oxidation

  1. Physical features of ultrasound-enhanced heterogeneous permanganate oxidation.

    PubMed

    Kuppa, Ramesh; Moholkar, Vijayanand S

    2010-01-01

    This paper addresses the matter of mechanistic features of ultrasound-assisted permanganate oxidation of organic compounds in aqueous phase. This reaction system is essentially a liquid-liquid heterogeneous one, which is limited by the mass transfer characteristics. Previous research has established that ultrasound irradiation of reaction mixture enhances the kinetics and yield of permanganate oxidation. The principal physical effect of ultrasonic cavitation is formation of fine emulsion between immiscible phases that eliminates the mass transfer resistance, while principal chemical effect is production of radicals through transient collapse of cavitation bubbles, which accelerate the reaction. In this paper, we have tried to discriminate between these physical and chemical effects by coupling experiments with different conditions (which alter the nature of cavitation phenomena in the medium) to simulations of cavitation bubble dynamics. It is revealed that in absence of radical conserving agent, the enhancement effect is merely physical. Diffusion of radicals towards interface between phases, where the oxidation reaction occurs is the limiting factor in contribution of chemical effect of ultrasonic cavitation towards enhancement of oxidation. Enhancement of total radical production in the aqueous phase (by degassing of the medium) increases the overall oxidation yield, but only marginally. On the other hand, addition of a radical conserver such as FeSO(4).7H(2)O results in marked enhancement in oxidation yield, as the conserver assists deeper penetration of radicals in the aqueous medium and diffusion towards interface.

  2. ABTS as an Electron Shuttle to Enhance the Oxidation Kinetics of Substituted Phenols by Aqueous Permanganate.

    PubMed

    Song, Yang; Jiang, Jin; Ma, Jun; Pang, Su-Yan; Liu, Yong-Ze; Yang, Yi; Luo, Cong-Wei; Zhang, Jian-Qiao; Gu, Jia; Qin, Wen

    2015-10-06

    In this study, it was, interestingly, found that 2,2'-azino-bis(3-ethylbenzothiazoline)-6-sulfonate (ABTS), a widely used electron shuttle, could greatly accelerate the oxidation of substituted phenols by potassium permanganate (Mn(VII)) in aqueous solutions at pH 5-9. This was attributed to the fact that these substituted phenols could be readily oxidized by the stable radical cation (ABTS(•+)), which was quickly produced from the oxidation of ABTS by Mn(VII). The reaction of Mn(VII) with ABTS exhibited second-order kinetics, with stoichiometries of ∼5:1 at pH 5-6 and ∼3:1 at pH 7-9, and the rate constants varied negligibly from pH 5 to 9 (k = (9.44 ± 0.21) × 10(4) M(-1) s(-1)). Comparatively, the reaction of ABTS(•+) with phenol showed biphasic kinetics. The second-order rate constants for the reactions of ABTS(•+) with substituted phenols obtained in the initial phase were strongly affected by pH, and they were several orders of magnitude higher than those for the reactions of Mn(VII) with substituted phenols at each pH. Good Hammett-type correlations were found for the reactions of ABTS(•+) with undissociated (log(k) = 2.82-4.31σ) and dissociated phenols (log(k) = 7.29-5.90σ). The stoichiometries of (2.2 ± 0.06):1 (ABTS(•+) in excess) and (1.38 ± 0.18):1 (phenol in excess) were achieved in the reaction of ABTS(•+) with phenol, but they exhibited no pH dependency.

  3. Enhanced permanganate in situ chemical oxidation through MnO 2 particle stabilization: Evaluation in 1-D transport systems

    NASA Astrophysics Data System (ADS)

    Crimi, Michelle; Quickel, Mark; Ko, Saebom

    2009-02-01

    In situ chemical oxidation using permanganate is an increasingly employed approach to organic contaminant remediation at hazardous waste sites. Manganese dioxide (MnO 2) particles form as a by-product of the reaction of permanganate with contaminants and naturally-reduced subsurface materials. These particles are of interest because they have the potential to deposit in the subsurface and impact the flow regime in/around permanganate injection, including the well screen, filter pack, and the surrounding subsurface formation. Control of these particles can allow for improved oxidant injection and transport, and contact between the oxidant and contaminants of concern. Sodium hexametaphosphate (HMP) has previously been identified as a promising aid to stabilize MnO 2 in solution when included in the oxidizing solution, increasing the potential to inhibit particle deposition and impact subsurface flow. The goal of the experimental studies described herein was to investigate the ability of HMP to prevent particle deposition in transport studies using four different types of porous media. Permanganate was delivered to a contaminant source zone (trichloroethylene) located within four different media types with variations in sand, clay, organic carbon, and iron oxides (as goethite) content. Deposition of MnO 2 within the columns was quantified with distance from the source zone. Experiments were repeated in replicate columns with the inclusion of HMP directly with the oxidant delivery solution, and MnO 2 deposition was again quantified. While total MnO 2 deposition within the 60 cm columns did not change significantly with the addition of HMP, deposition within the contaminant source zone decreased by 25-85%, depending on the specific media type. The greatest differences in deposition were observed in the goethite-containing and clay-containing columns. Columns containing these two media types experienced completely plugged flow in the oxidant-only delivery systems

  4. Microcystis aeruginosa-laden water treatment using enhanced coagulation by persulfate/Fe(II), ozone and permanganate: Comparison of the simultaneous and successive oxidant dosing strategy.

    PubMed

    Liu, Bin; Qu, Fangshu; Chen, Wei; Liang, Heng; Wang, Tianyu; Cheng, Xiaoxiang; Yu, Huarong; Li, Guibai; Van der Bruggen, Bart

    2017-08-15

    In this study, the application of enhanced coagulation with persulfate/Fe(II), permanganate and ozone for Microcystis-laden water treatment was investigated. Two oxidant dosage strategies were compared in terms of the organic removal performance: a simultaneous dosing strategy (SiDS) and a successive dosing strategy (SuDS). To optimize the oxidant species, oxidant doses and oxidant dosage strategy, the zeta potential, floc size and dimension fraction, potassium release and organic removal efficiency during the coagulation of algae-laden water were systematically investigated and comprehensively discussed. Ozonation causes most severe cell lysis and reduces organic removal efficiency because it releases intracellular organics. Moreover, ozonation can cause the release of odor compounds such as 2-methylisoborneol (2-MIB) and geosmin (GSM). With increasing doses, the performance of pollutant removal by coagulation enhanced by persulfate/Fe(II) or permanganate did not noticeably improve, which suggests that a low dosage of persulfate/Fe(II) and permanganate is the optimal strategy to enhance coagulation of Microcystis-laden water. The SiDS performs better than the SuDS because more Microcystis cell lysis occurs and less DOC is removed when oxidants are added before the coagulants. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. [Kinetics on ethanethiol oxidation by potassium permanganate in drinking water].

    PubMed

    Liu, Yao; Zhang, Xiao-Jian; Dai, Ji-Sheng; Xu, Huan

    2008-05-01

    Reaction kinetics of ethanethiol oxidation with potassium permanganate in water was studied, and the effect of ethanethiol oxidation in raw water under coagulation condition has been investigated. The results showed that the oxidation reaction of ethanethiol by potassium permanganate was very efficient, the removing effect could be more than 90%. The rate of ethanethiol decomposition by potassium permanganate in aqueous solution followed second-order kinetics. When potassium permanganate was excessive, pseudo-first-order rate and concentration of potassium permanganate followed the equation: k' = 0.025 [KMnO4] - 0.008. And then, the second-order reaction rate constant was k = 0.025 L/(min x mg). The removal of ethanethiol in raw water by potassium permanganate under coagulation condition was poorer than in pure water condition, So predicted concentration of potassium permanganate was lower than real concentration.

  6. Acid-permanganate oxidation of potassium tetraphenylboron

    SciTech Connect

    Smith, J.R.

    1993-02-01

    Scoping experiments have been performed which show that potassium tetraphenylboron (KTPB) is rapidly oxidized by permanganate in acidic solutions at room temperature. The main Products are CO[sub 2], highly oxidized organic compounds related to tartaric and tartronic acids, boric acid, and potassium phosphate (when phosphoric acid is used as the source of acid). One liter of 0.6M NaMnO[sub 4]/2.5M H[sub 3]PO[sub 4] solution will destroy up to 8 grams of KTPB. The residual benzene concentration has been measured to be less than the RCRA limit of 0.5 ppm. Approximately 30% of the organic material is released as CO[sub 2] (trace CO) and 0.16% as benzene vapor. The reaction is well behaved, no foaming or spattering. Tests were performed from .15M to near 1M permanganate. The phosphoric acid concentration was maintained at a concentration at least three times that of the permanganate since an excess of acid was desired and this is the ratio that these two reagents are consumed in the oxidation.

  7. Acid-permanganate oxidation of potassium tetraphenylboron

    SciTech Connect

    Smith, J.R.

    1993-02-01

    Scoping experiments have been performed which show that potassium tetraphenylboron (KTPB) is rapidly oxidized by permanganate in acidic solutions at room temperature. The main Products are CO{sub 2}, highly oxidized organic compounds related to tartaric and tartronic acids, boric acid, and potassium phosphate (when phosphoric acid is used as the source of acid). One liter of 0.6M NaMnO{sub 4}/2.5M H{sub 3}PO{sub 4} solution will destroy up to 8 grams of KTPB. The residual benzene concentration has been measured to be less than the RCRA limit of 0.5 ppm. Approximately 30% of the organic material is released as CO{sub 2} (trace CO) and 0.16% as benzene vapor. The reaction is well behaved, no foaming or spattering. Tests were performed from .15M to near 1M permanganate. The phosphoric acid concentration was maintained at a concentration at least three times that of the permanganate since an excess of acid was desired and this is the ratio that these two reagents are consumed in the oxidation.

  8. Ruthenium nanoparticles supported on CeO2 for catalytic permanganate oxidation of butylparaben.

    PubMed

    Zhang, Jing; Sun, Bo; Guan, Xiaohong; Wang, Hui; Bao, Hongliang; Huang, Yuying; Qiao, Junlian; Zhou, Gongming

    2013-11-19

    This study developed a heterogeneous catalytic permanganate oxidation system with ceria supported ruthenium, Ru/CeO2 (0.8‰ as Ru), as catalyst for the first time. The catalytic performance of Ru/CeO2 toward butylparaben (BP) oxidation by permanganate was strongly dependent on its dosage, pH, permanganate concentration and temperature. The presence of 1.0 g L(-1) Ru/CeO2 increased the oxidation rate of BP by permanganate at pH 4.0-8.0 by 3-96 times. The increase in Ru/CeO2 dosage led to a progressive enhancement in the oxidation rate of BP by permanganate at neutral pH. The XANES analysis revealed that (1) Ru was deposited on the surface of CeO2 as Ru(III); (2) Ru(III) was oxidized by permanganate to its higher oxidation state Ru(VI) and Ru(VII), which acted as the co-oxidants in BP oxidation; (3) Ru(VI) and Ru(VII) were reduced by BP to its initial state of Ru(III). Therefore, Ru/CeO2 acted as an electron shuttle in catalytic permanganate oxidation process. LC-MS/MS analysis implied that BP was initially attacked by permanganate or Ru(VI) and Ru(VII) at the aromatic ring, leading to the formation of various hydroxyl-substituted and ring-opening products. Ru/CeO2 could maintain its catalytic activity during the six successive runs. In conclusion, catalyzing permanganate oxidation with Ru/CeO2 is a promising technology for degrading phenolic pollutants in water treatment.

  9. Effects of Potassium Permanganate Oxidation on Subsurface Microbial Activity

    NASA Technical Reports Server (NTRS)

    Rowland, Martin A.; Brubaker, Gaylen R.; Westray, Mark; Morris, Damon; Kohler, Keisha; McCool, Alex (Technical Monitor)

    2001-01-01

    In situ chemical oxidation has the potential for degrading large quantities of organic contaminants and can be more effective and timely than traditional ex situ treatment methods. However, there is a need to better characterize the potential effects of this treatment on natural processes. This study focuses on potential inhibition to anaerobic dechlorination of trichloroethene (TCE) in soils from a large manufacturing facility as a result of in situ oxidation using potassium permanganate (KMn04)Previous microcosm studies established that natural attenuation occurs on-site and that it is enhanced by the addition of ethanol to the system. A potential remediation scheme for the site involves the use of potassium permanganate to reduce levels of TCE in heavily contaminated areas, then to inject ethanol into the system to "neutralize" excess oxidant and enhance microbial degradation. However, it is currently unknown whether the exposure of indigenous microbial populations to potassium permanganate may adversely affect biological reductive dechlorination by these microorganisms. Consequently, additional microcosm studies were conducted to evaluate this remediation scheme and assess the effect of potassium permanganate addition on biological reductive dechlorination of TCE. Samples of subsurface soil and groundwater were collected from a TCE-impacted area of the site. A portion of the soil was pretreated with nutrients and ethanol to stimulate microbial activity, while the remainder of the soil was left unamended. Soil/groundwater microcosms were prepared in sealed vials using the nutrient-amended and unamended soils, and the effects of potassium permanganate addition were evaluated using two permanganate concentrations (0.8 and 2.4 percent) and two contact times (1 and 3 weeks). TCE was then re-added to each microcosm and TCE and dichloroethene (DCE) concentrations were monitored to determine the degree to which microbial dechlorination occurred following chemical

  10. Oxidation of sulfamethoxazole (SMX) by chlorine, ozone and permanganate--a comparative study.

    PubMed

    Gao, Shanshan; Zhao, Zhiwei; Xu, Yongpeng; Tian, Jiayu; Qi, Hong; Lin, Wei; Cui, Fuyi

    2014-06-15

    Sulfamethoxazole (SMX), a typical sulfonamide antibiotic, has been widely detected in secondary wastewater effluents and surface waters. In this work we investigated the oxidative degradation of SMX by commonly used oxidants of chlorine, ozone and permanganate. Chlorine and ozone were shown to be more effective for the removal of SMX (0.05-5.0mg/L), as compared with permanganate. Higher pH enhanced the oxidation of SMX by ozone and permanganate, but decreased the removal by chlorine. Moreover, the ozonation of SMX was significantly influenced by the presence of humic acid (HA), which exhibited negligible influence on the oxidation by chlorine and permanganate. Fairly lower mineralization of SMX occurred during the oxidation reactions, with the highest dissolved organic carbon (DOC) removal of 13% (for ozone). By using LC-MS/MS, 7, 5 and 5 oxidation products were identified for chlorine, ozone and permanganate and possible transformation pathways were proposed. It was shown that different oxidants shared some common pathways, such as the cleavage of SN bond, the hydroxylation of the benzene ring, etc. On the other hand, each of the oxidants also exhibited exclusive degradation mechanisms, leading to the formation of different transformation products (TPs). This work may provide useful information for the selection of oxidants in water treatment processes.

  11. Control of Manganese Dioxide Particles Resulting From In Situ Chemical Oxidation Using Permanganate

    DTIC Science & Technology

    2008-09-01

    permanganate oscillating reactions. J. Am. Chem. Soc., 115:9683-9686. Insausti M.J., F. Mata-Perez, and P. Alvarez- Macho (1992). Permanganate...Mata-Perez, and P. Alvarez- Macho (1993). UV-VIS spectrophotometric study and dynamic analysis on the colloidal product of permanganate oxidation of a

  12. Ru(III) catalyzed permanganate oxidation of aniline at environmentally relevant pH.

    PubMed

    Zhang, Jing; Zhang, Ying; Wang, Hui; Guan, Xiaohong

    2014-07-01

    Ru(III) was employed as catalyst for aniline oxidation by permanganate at environmentally relevant pH for the first time. Ru(III) could significantly improve the oxidation rate of aniline by 5-24 times with its concentration increasing from 2.5 to 15 μmol/L. The reaction of Ru(III) catalyzed permanganate oxidation of aniline was first-order with respect to aniline, permanganate and Ru(III), respectively. Thus the oxidation kinetics can be described by a third-order rate law. Aniline degradation by Ru(III) catalyzed permanganate oxidation was markedly influenced by pH, and the second-order rate constant (ktapp) decreased from 643.20 to 2.67 (mol/L)⁻¹sec⁻¹ with increasing pH from 4.0 to 9.0, which was possibly due to the decrease of permanganate oxidation potential with increasing pH. In both the uncatalytic and catalytic permanganate oxidation, six byproducts of aniline were identified in UPLC-MS/MS analysis. Ru(III), as an electron shuttle, was oxidized by permanganate to Ru(VI) and Ru(VII), which acted the co-oxidants for decomposition of aniline. Although Ru(III) could catalyze permanganate oxidation of aniline effectively, dosing homogeneous Ru(III) into water would lead to a second pollution. Therefore, efforts would be made to investigate the catalytic performance of supported Ru(III) toward permanganate oxidation in our future study.

  13. Enhanced degradation of Orange G by permanganate with the employment of iron anode.

    PubMed

    Bu, Lingjun; Shi, Zhou; Zhou, Shiqing

    2017-01-01

    Iron anode was employed to enhance the degradation of Orange G (OG) by permanganate (EC/KMnO4). Continuously generated Fe(2+) from iron anode facilitated the formation of fresh MnO2, which plays a role in catalyzing permanganate oxidation. The EC/KMnO4 system also showed a better performance to remove OG than Fe(2+)/KMnO4, indicating the importance of in situ formed fresh MnO2. Besides, the effects of applied current, KMnO4 dosage, solution pH, and natural organics were evaluated and results demonstrated that high current and oxidant dosage are favorable for OG removal. And the application of iron anode has a promoting effect on the KMnO4 oxidation over a wide pH range (5.0-9.0), while the Fe(2+)/KMnO4 process does not. For natural organics, its presence could inhibit OG removal due to its competitive role. And the promoting effect of OG removal by the EC/KMnO4 process in natural water was confirmed. At last, the EC/KMnO4 process showed a satisfying performance on the decolorization and mineralization of OG. This study provides a potential technology to enhance permanganate oxidation and broadens the knowledge of azo dye removal.

  14. Parabola-like shaped pH-rate profile for phenols oxidation by aqueous permanganate.

    PubMed

    Du, Juanshan; Sun, Bo; Zhang, Jing; Guan, Xiaohong

    2012-08-21

    Oxidation of phenols by permanganate in the pH range of 5.0-9.0 generally exhibits a parabola-like shape with the maximum reaction rate obtained at pH close to phenols' pK(a). However, a monotonic increase or decrease is observed if phenols' pK(a) is beyond the pH range of 5.0-9.0. A proton transfer mechanism is proposed in which the undissociated phenol is directly oxidized by permanganate to generate products while a phenolate-permanganate adduct, intermediate, is formed between dissociated phenol and permanganate ion and this is the rate-limiting step for phenolates oxidation by permanganate. The intermediate combines with H(+) and then decomposes to products. Rate equations derived based on the steady-state approximation can well simulate the experimentally derived pH-rate profiles. Linear free energy relationships (LFERs) were established among the parameters obtained from the modeling, Hammett constants, and oxygen natural charges in phenols and phenolates. LFERs reveal that chlorine substituents have opposite influence on the susceptibility of phenols and phenolates to permanganate oxidation and phenolates are not necessarily more easily oxidized than their neutral counterparts. The chlorine substituents regulate the reaction rate of chlorophenolates with permanganate mainly by influencing the natural charges of the oxygen atoms of dissociated phenols while they influence the oxidation of undissociated chlorophenols by permanganate primarily by forming intramolecular hydrogen bonding with the phenolic group.

  15. Removal of emerging pollutants by Ru/TiO2-catalyzed permanganate oxidation.

    PubMed

    Zhang, Jing; Sun, Bo; Xiong, Xinmei; Gao, Naiyun; Song, Weihua; Du, Erdeng; Guan, Xiaohong; Zhou, Gongming

    2014-10-15

    TiO2 supported ruthenium nanoparticles, Ru/TiO2 (0.94‰ as Ru), was synthesized to catalyze permanganate oxidation for degrading emerging pollutants (EPs) with diverse organic moieties. The presence of 1.0 g L(-1) Ru/TiO2 increased the second order reaction rate constants of bisphenol A, diclofenac, acetaminophen, sulfamethoxazole, benzotriazole, carbamazepine, butylparaben, diclofenac, ciprofloxacin and aniline at mg L(-1) level (5.0 μM) by permanganate oxidation at pH 7.0 by 0.3-119 times. The second order reaction rate constants of EPs with permanganate or Ru/TiO2-catalyzed permanganate oxidation obtained at EPs concentration of mg L(-1) level (5.0 μM) underestimated those obtained at EPs concentration of μg L(-1) level (0.050 μM). Ru/TiO2-catalyzed permanganate could decompose a mixture of nine EPs at μg L(-1) level efficiently and the second order rate constant for each EP was not decreased due to the competition of other EPs. The toxicity tests revealed that Ru/TiO2-catalyzed permanganate oxidation was effective not only for elimination of EPs but also for detoxification. The removal rates of sulfamethoxazole by Ru/TiO2-catalyzed permanganate oxidation in ten successive cycles remained almost constant in ultrapure water and slightly decreased in Songhua river water since the sixth run, indicating the satisfactory stability of Ru/TiO2. Ru/TiO2-catalyzed permanganate oxidation was selective and could remove selected EPs spiked in real waters more efficiently than chlorination. Therefore, Ru/TiO2-catalyzed permanganate oxidation is promising for removing EPs with electron-rich moieties. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. The state of permanganate with relation to in situ chemical oxidation

    SciTech Connect

    Veronda, Brenda; Dingens, Matthew

    2007-07-01

    In Situ Chemical Oxidation (ISCO) with permanganate had its beginnings over 10 years ago. Since that time, many sites have been successfully treated for organic compounds including chlorinated ethenes (perchloroethylene, trichloroethylene, etc.) phenols, explosives such as RDX, and many other organics. The successful application of ISCO with permanganate requires the integration of many site-specific factors into the remedial design. ISCO with permanganate is an effective technology, not only for its oxidative properties and persistence, but also for its application flexibility to remediate soil and groundwater. The merits of any type of treatment technology can be assessed in terms of effectiveness, ease of use, reaction rate, and cost. The use of permanganate for in situ chemical oxidation results in the complete mineralization of TCE and PCE and can result in treatment levels below detection limits. Permanganate is a single component oxidizer, which is easily handled, mixed and distributed to the subsurface. Permanganate is also inexpensive to design and implement as compared to other technologies. This presentation will provide a general overview of the application and safety aspects of ISCO with permanganate. This paper will discuss the advantages and limitations of this technology, typical cost ranges, site evaluation and application technologies. (authors)

  17. Kinetics of the oxidation of methyl tert-butyl ether (MTBE) by potassium permanganate.

    PubMed

    Damm, Jochen H; Hardacre, Christopher; Kalin, Robert M; Walsh, Kayleen P

    2002-08-01

    The occurrence of the fuel oxygenate methyl tert-butyl ether (MTBE) in the environment has received considerable scientific attention. The pollutant is frequently found in the groundwater due to leaking of underground storage tanks or pipelines. Concentrations of more than several mg/L MTBE were detected in groundwater at several places in the US and Germany in the last few years. In situ chemical oxidation is a promising treatment method for MTBE-contaminated plumes. This research investigated the reaction kinetics for the oxidation of MTBE by permanganate. Batch tests demonstrated that the oxidation of MTBE by permanganate is second order overall and first order individually with respect to permanganate and MTBE. The second-order rate constant was 1.426 x 10(-6) L/mg/h. The influence of pH on the reaction rate was demonstrated to have no significant effect. However, the rate of MTBE oxidation by potassium permanganate is 2-3 orders of magnitude lower than of other advanced oxidation processes. The slower rates of MTBE oxidation by permanganate limit the applicability of this process for rapid MTBE cleanup strategies. However, permanganate oxidation of MTBE has potential for passive oxidation risk management strategies.

  18. In Situ Oxidation of Liquid Trichloroethylene by Permanganate Solutions: Preliminary Results of Column Studies

    SciTech Connect

    Schroth, Martin H.; Oostrom, Mart; Wietsma, Thomas W.; Istok, Jonathan D.; H.J. Morel-Seytoux

    2000-01-11

    In situ oxidation of liquid trichloroethylene by permanganate solutions: Preliminary results of column studies. In: Proceedings of the 19th American Geophysical Union Hydrology Days, H. J. Morel-Seytoux, ed., pp. 411-420. Hydrology Days Pub., Atherton, Ca.

  19. Process Development for Permanganate Addition During Oxidative Leaching of Hanford Tanks Sludges

    SciTech Connect

    Rapko, Brian M.; Lumetta, Gregg J.; Deschane, Jaquetta R.; Peterson, Reid A.; Blanchard, David L.

    2007-10-30

    Previous Bechtel National, Incorporated (BNI)-sponsored studies have targeted optimizing sodium permanganate for the selective oxidation of chromium from washed Hanford tank sludges (Rapko et al. 2004; Rapko et al. 2005). The recommendation from previous work was that contact with sodium permanganate in a minimally caustic solution, i.e., 0.1 to 0.25 M [OH-] initially, provided maximum Cr dissolution while minimizing concomitant Pu dissolution. At the request of BNI, further work on oxidative alkaline leaching was performed.

  20. Oxidation kinetics of antibiotics during water treatment with potassium permanganate.

    PubMed

    Hu, Lanhua; Martin, Heather M; Strathmann, Timothy J

    2010-08-15

    The ubiquitous occurrence of antibiotics in aquatic environments raises concerns about potential adverse effects on aquatic ecology and human health, including the promotion of increased antibiotic resistance. This study examined the oxidation of three widely detected antibiotics (ciprofloxacin, lincomycin, and trimethoprim) by potassium permanganate [KMnO(4); Mn(VII)]. Reaction kinetics were described by second-order rate laws, with apparent second-order rate constants (k(2)) at pH 7 and 25 degrees C in the order of 0.61 +/- 0.02 M(-1) s(-1) (ciprofloxacin) < 1.6 +/- 0.1 M(-1) s(-1) (trimethoprim) < 3.6 +/- 0.1 M(-1) s(-1) (lincomycin). Arrhenius temperature dependence was observed with apparent activation energies (E(a)) ranging from 49 kJ mol(-1) (trimethoprim) to 68 kJ mol(-1) (lincomycin). Rates of lincomycin and trimethoprim oxidation exhibited marked pH dependences, whereas pH had only a small effect on rates of ciprofloxacin oxidation. The effects of pH were quantitatively described by considering parallel reactions between KMnO(4) and individual acid-base species of the target antibiotics. Predictions from a kinetic model that included temperature, KMnO(4) dosage, pH, and source water oxidant demand as input parameters agreed reasonably well with measurements of trimethoprim and lincomycin oxidation in six drinking water utility sources. Although Mn(VII) reactivity with the antibiotics was lower than that reported for ozone and free chlorine, its high selectivity and stability suggests a promising oxidant for treating sensitive micropollutants in organic-rich matrices (e.g., wastewater).

  1. Permanganate-based synthesis of manganese oxide nanoparticles in ferritin

    NASA Astrophysics Data System (ADS)

    Olsen, Cameron R.; Smith, Trevor J.; Embley, Jacob S.; Maxfield, Jake H.; Hansen, Kameron R.; Peterson, J. Ryan; Henrichsen, Andrew M.; Erickson, Stephen D.; Buck, David C.; Colton, John S.; Watt, Richard K.

    2017-05-01

    This paper investigates the comproportionation reaction of MnII with {{{{MnO}}}4}- as a route for manganese oxide nanoparticle synthesis in the protein ferritin. We report that {{{{MnO}}}4}- serves as the electron acceptor and reacts with MnII in the presence of apoferritin to form manganese oxide cores inside the protein shell. Manganese loading into ferritin was studied under acidic, neutral, and basic conditions and the ratios of MnII and permanganate were varied at each pH. The manganese-containing ferritin samples were characterized by transmission electron microscopy, UV/Vis absorption, and by measuring the band gap energies for each sample. Manganese cores were deposited inside ferritin under both the acidic and basic conditions. All resulting manganese ferritin samples were found to be indirect band gap materials with band gap energies ranging from 1.01 to 1.34 eV. An increased UV/Vis absorption around 370 nm was observed for samples formed under acidic conditions, suggestive of MnO2 formation inside ferritin.

  2. Permanganate-Based Synthesis of Manganese Oxide Nanoparticles in Ferritin.

    PubMed

    Olsen, Cameron; Smith, Trevor; Embley, Jacob; Maxfield, Jake; Hansen, Kameron; Peterson, J; Henrichsen, Andrew; Erickson, Stephen; Buck, David; Colton, John S; Watt, Richard

    2017-03-23

    This paper investigates the comproportionation reaction of MnII with MnO4- as a route for manganese oxide nanoparticle synthesis in the protein ferritin. We report that MnO4- serves as the electron acceptor and reacts with MnII in the presence of apoferritin to form manganese oxide cores inside the protein shell. Manganese loading into ferritin was studied under acidic, neutral, and basic conditions and the ratios of MnII and permanganate were varied at each pH. The manganese-containing ferritin samples were characterized by transmission electron microscopy, UV/Vis absorption, and by measuring the band gap energies for each sample. Manganese cores were deposited inside ferritin under both the acidic and basic conditions. All resulting manganese ferritin samples were found to be indirect band gap materials with band gap energies ranging from 1.01 eV to 1.34 eV. An increased UV/Vis absorption around 370 nm was observed for samples formed under acidic conditions, suggestive of MnO2 formation inside ferritin.

  3. Oxidation of microcystins by permanganate: reaction kinetics and implications for water treatment.

    PubMed

    Rodríguez, Eva; Majado, María E; Meriluoto, Jussi; Acero, Juan L

    2007-01-01

    A few genera of cyanobacteria produce toxins which contaminate drinking water resources. Microcystins (MC), widely reported cyanotoxins, cause acute and chronic toxicity effects in living beings including humans and warrant removal from drinking water. In the present study, unknown second-order rate constants for the reactions of microcystin-LR (MC-LR), -RR and -YR with potassium permanganate were determined at pH 6.2-8.2 and temperature 10-25 degrees C. The reaction of permanganate with MCs is second-order overall and first-order with respect to both permanganate and toxin. The second-order rate constant for the reaction of MC-LR with permanganate at pH 7 and 20 degrees C was 357.2+/-17.5M(-1)s(-1). The influence of pH on the oxidation process was not appreciable and the activation energy was 28.8 kJ mol(-1). Slightly higher reactivity with permanganate was found for MC-RR (418.0M(-1)s(-1)) and MC-YR (405.9M(-1)s(-1)). According to the results obtained, permanganate likely attacks the Adda moiety of the MC molecule. The oxidation of MCs in a natural surface water was also investigated. A permanganate dose of 1-1.25mgL(-1) was enough to reduce MCs concentration below the guideline value of 1microgL(-1). Permanganate oxidation is therefore a feasible option for microcystin removal during preoxidation processes. However, the oxidant dose must be carefully optimized in order to remove extracellular MCs without causing cell lysis (due to chemical stress) and further release of MCs.

  4. Time series geophysical monitoring of permanganate injections and in situ chemical oxidation of PCE, OU1 area, Savage Superfund Site, Milford, NH, USA.

    PubMed

    Harte, Philip T; Smith, Thor E; Williams, John H; Degnan, James R

    2012-05-01

    In situ chemical oxidation (ISCO) treatment with sodium permanganate, an electrically conductive oxidant, provides a strong electrical signal for tracking of injectate transport using time series geophysical surveys including direct current (DC) resistivity and electromagnetic (EM) methods. Effective remediation is dependent upon placing the oxidant in close contact with the contaminated aquifer. Therefore, monitoring tools that provide enhanced tracking capability of the injectate offer considerable benefit to guide subsequent ISCO injections. Time-series geophysical surveys were performed at a superfund site in New Hampshire, USA over a one-year period to identify temporal changes in the bulk electrical conductivity of a tetrachloroethylene (PCE; also called tetrachloroethene) contaminated, glacially deposited aquifer due to the injection of sodium permanganate. The ISCO treatment involved a series of pulse injections of sodium permanganate from multiple injection wells within a contained area of the aquifer. After the initial injection, the permanganate was allowed to disperse under ambient groundwater velocities. Time series geophysical surveys identified the downward sinking and pooling of the sodium permanganate atop of the underlying till or bedrock surface caused by density-driven flow, and the limited horizontal spread of the sodium permanganate in the shallow parts of the aquifer during this injection period. When coupled with conventional monitoring, the surveys allowed for an assessment of ISCO treatment effectiveness in targeting the PCE plume and helped target areas for subsequent treatment. Published by Elsevier B.V.

  5. Time series geophysical monitoring of permanganate injections and in situ chemical oxidation of PCE, OU1 area, Savage Superfund Site, Milford, NH, USA

    USGS Publications Warehouse

    Harte, Philip T.; Smith, Thor E.; Williams, John H.; Degnan, James R.

    2012-01-01

    In situ chemical oxidation (ISCO) treatment with sodium permanganate, an electrically conductive oxidant, provides a strong electrical signal for tracking of injectate transport using time series geophysical surveys including direct current (DC) resistivity and electromagnetic (EM) methods. Effective remediation is dependent upon placing the oxidant in close contact with the contaminated aquifer. Therefore, monitoring tools that provide enhanced tracking capability of the injectate offer considerable benefit to guide subsequent ISCO injections. Time-series geophysical surveys were performed at a superfund site in New Hampshire, USA over a one-year period to identify temporal changes in the bulk electrical conductivity of a tetrachloroethylene (PCE; also called tetrachloroethene) contaminated, glacially deposited aquifer due to the injection of sodium permanganate. The ISCO treatment involved a series of pulse injections of sodium permanganate from multiple injection wells within a contained area of the aquifer. After the initial injection, the permanganate was allowed to disperse under ambient groundwater velocities. Time series geophysical surveys identified the downward sinking and pooling of the sodium permanganate atop of the underlying till or bedrock surface caused by density-driven flow, and the limited horizontal spread of the sodium permanganate in the shallow parts of the aquifer during this injection period. When coupled with conventional monitoring, the surveys allowed for an assessment of ISCO treatment effectiveness in targeting the PCE plume and helped target areas for subsequent treatment.

  6. Time series geophysical monitoring of permanganate injections and in situ chemical oxidation of PCE, OU1 area, Savage Superfund Site, Milford, NH, USA

    NASA Astrophysics Data System (ADS)

    Harte, Philip T.; Smith, Thor E.; Williams, John H.; Degnan, James R.

    2012-05-01

    In situ chemical oxidation (ISCO) treatment with sodium permanganate, an electrically conductive oxidant, provides a strong electrical signal for tracking of injectate transport using time series geophysical surveys including direct current (DC) resistivity and electromagnetic (EM) methods. Effective remediation is dependent upon placing the oxidant in close contact with the contaminated aquifer. Therefore, monitoring tools that provide enhanced tracking capability of the injectate offer considerable benefit to guide subsequent ISCO injections. Time-series geophysical surveys were performed at a superfund site in New Hampshire, USA over a one-year period to identify temporal changes in the bulk electrical conductivity of a tetrachloroethylene (PCE; also called tetrachloroethene) contaminated, glacially deposited aquifer due to the injection of sodium permanganate. The ISCO treatment involved a series of pulse injections of sodium permanganate from multiple injection wells within a contained area of the aquifer. After the initial injection, the permanganate was allowed to disperse under ambient groundwater velocities. Time series geophysical surveys identified the downward sinking and pooling of the sodium permanganate atop of the underlying till or bedrock surface caused by density-driven flow, and the limited horizontal spread of the sodium permanganate in the shallow parts of the aquifer during this injection period. When coupled with conventional monitoring, the surveys allowed for an assessment of ISCO treatment effectiveness in targeting the PCE plume and helped target areas for subsequent treatment.

  7. Permanganate oxidation of sulfur compounds to prevent poisoning of Pd catalysts in water treatment processes.

    PubMed

    Angeles-Wedler, Dalia; Mackenzie, Katrin; Kopinke, Frank-Dieter

    2008-08-01

    The practical application of Pd-catalyzed water treatment processes is impeded by catalyst poisoning by reduced sulfur compounds (RSCs). In this study, the potential of permanganate as a selective oxidant for the removal of microbially generated RSCs in water and as a regeneration agent for S-poisoned catalysts was evaluated. Hydrodechlorination using Pd/Al2O3 was carried out as a probe reaction in permanganate-pretreated water. The activity of the Pd catalysts in the successfully pretreated reaction medium was similar to that in deionized water. The catalyst showed no deactivation behavior in the presence of permanganate at a concentration level < or = 0.07 mM. With a residual oxidant concentration of > or = 0.08 mM, a significant but temporary inhibition of the catalytic dechlorination was observed. Unprotected Pd/Al2O3, which had been completely poisoned by sulfide, was reactivated by a combined treatment with permanganate and hydrazine. However, the anthropogenic water pollutants thiophene and carbon disulfide were resistant against permanganate. Together with the preoxidation of catalyst poisons, hydrophobic protection of the catalysts was studied. Pd/zeolite and various hydrophobically coated catalysts showed a higher stability against ionic poisons and permanganate than the uncoated catalyst. By means of a combination of oxidative water pretreatment and hydrophobic catalyst protection, we provide a new tool to harness the potential of Pd-catalyzed hydrodehalogenation for the treatment of real waters.

  8. Carbon isotope fractionation during permanganate oxidation of chlorinated ethylenes (cDCE, TCE, PCE).

    PubMed

    Poulson, Simon R; Naraoka, Hiroshi

    2002-08-01

    Permanganate oxidation of chlorinated ethylenes is an attractive technique to effect remediation of these important groundwater contaminants. Stable carbon isotope fractionation associated with permanganate oxidation of trichloroethylene (TCE), tetrachloroethylene (PCE), and cis-1,2-dichloroethylene (cDCE) has been measured, to study the possibility of applying stable carbon isotope analysis as a technique to assess the efficacy of remediation implemented by permanganate oxidation. Average carbon isotope fractionation factors of alphaTCE = 0.9786, alphaPCE = 0.9830, and alphacDCE = 0.9789 were obtained, although the fractionation factor for PCE may be interpreted to change from a value of 0.9779-0.9871 during the course of the reaction. The fractionation factors for all three compounds are quite similar, in contrast to the variation of fractionation factors vs degree of chlorination observed for other degradative processes, such as microbial dechlorination. This may be due to a common rate-determining step for permanganate oxidation of all three compounds studied. The large fractionation factors and the relative lack of dependence of the fractionation factors upon other environmental factors (e.g. oxidation rate, presence of multiple contaminants, incomplete oxidation, presence of chloride in solution) indicate that monitoring delta13C values of chlorinated ethylenes during oxidation with permanganate may be a sensitive, and potentially quantitative, technique to investigate the extent of degradation.

  9. [Mechanism of natural organic matter removal by potassium permanganate composite enhanced coagulation].

    PubMed

    Zhang, Yong-Ji; Zhou, Ling-Ling; Li, Wei-Ying; Li, Xing; Li, De-Qiang; Li, Gui-Bai

    2009-03-15

    Streaming current technique, fluctuation of transmitted light technique, molecular weight distribution and XAD resin adsorption technique were used to study the mechanism of natural organic matter removal by potassium permanganate composite (PPC) enhanced coagulation. Results showed that natural organic matter removal efficiency increased 13% by 0.75 mg/L potassium permanganate composite enhanced coagulation compared with that of alum coagulation alone. Streaming current indicated that potassium permanganate composite decreased the organic matter stability by reducing the surface negative charge, and the SC value increased from 55.2 to 61.4, 69.6 and 87.0 by addition of 0.50, 0.75 and 1.0 mg/L PPC. Coagulation index R indicated both nascent manganese dioxide and subsidiaries played an important role in potassium permanganate composite enhanced coagulation process. Potassium permanganate composite enhanced coagulation increased the removal efficiency of lower molecular weight and hydrophilic organic matter compared with alum coagulation, and hydrophilic organic matter can be reduced from 1.9 mg/L to 1.32 mg/L by the addition of 0.75 mg/L potassium permanganate composite.

  10. Oxidative treatment of azo dyes in aqueous solution by potassium permanganate.

    PubMed

    Aleboyeh, A; Olya, M E; Aleboyeh, H

    2009-03-15

    This work was conducted to study the ability of permanganate (KMnO(4)) oxidative treatment as a method to decolourise the solutions containing azo dye C.I. Acid Orange 7, C.I. Acid Orange 8, C.I. Acid Red 14, or C.I. Acid Red 73, in a batch system. The results of the study demonstrated the complete removal of the colour and partial mineralization for each dye solution. The effect of the key operating variables such as initial dye concentration, permanganate amount, pH and temperature were studied. Decolourisation reactions were influenced by the acidity and temperature of the treated solutions. To avoid the overdose of KMnO(4), the stoichiometric amount of permanganate required for 1 mol of dye complete colour removal was determined. The reactions between permanganate and C.I. Acid Orange 7, C.I. Acid Orange 8, C.I. Acid Red 14 and C.I. Acid Red 73 dyes in acidic medium exhibit (2.05, 2.20, 2.42 and 2.79):1 stoichiometry (MnO(4)(-):dye). Dye degradation efficiency by potassium permanganate was studied, monitoring total organic carbon (TOC). The results indicated that the degradation efficiency of azo dyes increased with the increase of the potassium permanganate amount. Meanwhile, even in large excess of the oxidant, the dye mineralization was incomplete.

  11. Microbial Community Response of an Organohalide Respiring Enrichment Culture to Permanganate Oxidation

    PubMed Central

    Sutton, Nora B.; Atashgahi, Siavash; Saccenti, Edoardo; Grotenhuis, Tim; Smidt, Hauke; Rijnaarts, Huub H. M.

    2015-01-01

    While in situ chemical oxidation is often used to remediate tetrachloroethene (PCE) contaminated locations, very little is known about its influence on microbial composition and organohalide respiration (OHR) activity. Here, we investigate the impact of oxidation with permanganate on OHR rates, the abundance of organohalide respiring bacteria (OHRB) and reductive dehalogenase (rdh) genes using quantitative PCR, and microbial community composition through sequencing of 16S rRNA genes. A PCE degrading enrichment was repeatedly treated with low (25 μmol), medium (50 μmol), or high (100 μmol) permanganate doses, or no oxidant treatment (biotic control). Low and medium treatments led to higher OHR rates and enrichment of several OHRB and rdh genes, as compared to the biotic control. Improved degradation rates can be attributed to enrichment of (1) OHRB able to also utilize Mn oxides as a terminal electron acceptor and (2) non-dechlorinating community members of the Clostridiales and Deltaproteobacteria possibly supporting OHRB by providing essential co-factors. In contrast, high permanganate treatment disrupted dechlorination beyond cis-dichloroethene and caused at least a 2–4 orders of magnitude reduction in the abundance of all measured OHRB and rdh genes, as compared to the biotic control. High permanganate treatments resulted in a notably divergent microbial community, with increased abundances of organisms affiliated with Campylobacterales and Oceanospirillales capable of dissimilatory Mn reduction, and decreased abundance of presumed supporters of OHRB. Although OTUs classified within the OHR-supportive order Clostridiales and OHRB increased in abundance over the course of 213 days following the final 100 μmol permanganate treatment, only limited regeneration of PCE dechlorination was observed in one of three microcosms, suggesting strong chemical oxidation treatments can irreversibly disrupt OHR. Overall, this detailed investigation into dose

  12. Microbial Community Response of an Organohalide Respiring Enrichment Culture to Permanganate Oxidation.

    PubMed

    Sutton, Nora B; Atashgahi, Siavash; Saccenti, Edoardo; Grotenhuis, Tim; Smidt, Hauke; Rijnaarts, Huub H M

    2015-01-01

    While in situ chemical oxidation is often used to remediate tetrachloroethene (PCE) contaminated locations, very little is known about its influence on microbial composition and organohalide respiration (OHR) activity. Here, we investigate the impact of oxidation with permanganate on OHR rates, the abundance of organohalide respiring bacteria (OHRB) and reductive dehalogenase (rdh) genes using quantitative PCR, and microbial community composition through sequencing of 16S rRNA genes. A PCE degrading enrichment was repeatedly treated with low (25 μmol), medium (50 μmol), or high (100 μmol) permanganate doses, or no oxidant treatment (biotic control). Low and medium treatments led to higher OHR rates and enrichment of several OHRB and rdh genes, as compared to the biotic control. Improved degradation rates can be attributed to enrichment of (1) OHRB able to also utilize Mn oxides as a terminal electron acceptor and (2) non-dechlorinating community members of the Clostridiales and Deltaproteobacteria possibly supporting OHRB by providing essential co-factors. In contrast, high permanganate treatment disrupted dechlorination beyond cis-dichloroethene and caused at least a 2-4 orders of magnitude reduction in the abundance of all measured OHRB and rdh genes, as compared to the biotic control. High permanganate treatments resulted in a notably divergent microbial community, with increased abundances of organisms affiliated with Campylobacterales and Oceanospirillales capable of dissimilatory Mn reduction, and decreased abundance of presumed supporters of OHRB. Although OTUs classified within the OHR-supportive order Clostridiales and OHRB increased in abundance over the course of 213 days following the final 100 μmol permanganate treatment, only limited regeneration of PCE dechlorination was observed in one of three microcosms, suggesting strong chemical oxidation treatments can irreversibly disrupt OHR. Overall, this detailed investigation into dose

  13. Oxidation kinetics of crystal violet by potassium permanganate in acidic medium

    NASA Astrophysics Data System (ADS)

    Khan, Sameera Razi; Ashfaq, Maria; Mubashir; Masood, Summyia

    2016-05-01

    The oxidation kinetics of crystal violet (a triphenylmethane dye) by potassium permanganate was focused in an acidic medium by the spectrophotometric method at 584 nm. The oxidation reaction of crystal violet by potassium permanganate is carried out in an acidic medium at different temperatures ranging within 298-318 K. The kinetic study was carried out to investigate the effect of the concentration, ionic strength and temperature. The reaction followed first order kinetics with respect to potassium permanganate and crystal violet and the overall rate of the reaction was found to be second order. Thermodynamic activation parameters like the activation energy ( E a), enthalpy change (Δ H*), free energy change (Δ G*), and entropy change (Δ S*) have also been evaluated.

  14. XPERT DESIGN AND DIAGNOSTICS' (XDD) IN-SITU CHEMICAL OXIDATION PROCESS USING POTASSIUM PERMANGANATE (KMNO4)

    EPA Science Inventory

    Xpert Design and Diagnostic's (XDD)potassium permanganate in situ chemical oxidation (ISCO) process was evaluated under the EPA Superfund Innovative Technology Evaluation (SITE) Program at the former MEC Building site located in Hudson, New Hampshire. At this site, both soil and ...

  15. XPERT DESIGN AND DIAGNOSTICS' (XDD) IN-SITU CHEMICAL OXIDATION PROCESS USING POTASSIUM PERMANGANATE (KMNO4)

    EPA Science Inventory

    Xpert Design and Diagnostic's (XDD)potassium permanganate in situ chemical oxidation (ISCO) process was evaluated under the EPA Superfund Innovative Technology Evaluation (SITE) Program at the former MEC Building site located in Hudson, New Hampshire. At this site, both soil and ...

  16. Degradation of progestagens by oxidation with potassium permanganate in wastewater effluents

    PubMed Central

    2013-01-01

    Background This study investigated the oxidation of selected progestagenic steroid hormones by potassium permanganate at pH 6.0 and 8.0 in ultrapure water and wastewater effluents, using bench-scale assays. Second order rate constants for the reaction of potassium permanganate with progestagens (levonorgestrel, medroxyprogesterone, norethindrone and progesterone) was determined as a function of pH, presence of natural organic matter and temperature. This work also illustrates the advantages of using a novel analytical method, the laser diode thermal desorption (LDTD-APCI) interface coupled to tandem mass spectrometry apparatus, allowing for the quick determination of oxidation rate constants and increasing sample throughput. Results The second-order rate constants for progestagens with permanganate determined in bench-scale experiments ranged from 23 to 368 M-1 sec-1 in both wastewater and ultrapure waters with pH values of 6.0 and 8.0. Two pairs of progestagens exhibited similar reaction rate constants, i.e. progesterone and medroxyprogesterone (23 to 80 M-1 sec-1 in ultrapure water and 26 to 149 M-1 sec-1 in wastewaters, at pH 6.0 and 8.0) and levonorgestrel and norethindrone (179 to 224 M-1 sec-1 in ultrapure water and 180 to 368 M-1 sec-1 in wastewaters, at pH 6.0 and 8.0). The presence of dissolved natural organic matter and the pH conditions improved the oxidation rate constants for progestagens with potassium permanganate only at alkaline pH. Reaction rates measured in Milli-Q water could therefore be used to provide conservative estimates for the oxidation rates of the four selected progestagens in wastewaters when exposed to potassium permanganate. The progestagen removal efficiencies was lower for progesterone and medroxyprogesterone (48 to 87 %) than for levonorgestrel and norethindrone (78 to 97%) in Milli-Q and wastewaters at pH 6.0-8.2 using potassium permanganate dosages of 1 to 5 mg L-1 after contact times of 10 to 60

  17. Oxidative elimination of cyanotoxins: comparison of ozone, chlorine, chlorine dioxide and permanganate.

    PubMed

    Rodríguez, Eva; Onstad, Gretchen D; Kull, Tomas P J; Metcalf, James S; Acero, Juan L; von Gunten, Urs

    2007-08-01

    As the World Health Organization (WHO) progresses with provisional Drinking Water Guidelines of 1 microg/L for microcystin-LR and a proposed Guideline of 1 microg/L for cylindrospermopsin, efficient treatment strategies are needed to prevent cyanotoxins such as these from reaching consumers. A kinetic database has been compiled for the oxidative treatment of three cyanotoxins: microcystin-LR (MC-LR), cylindrospermopsin (CYN), and anatoxin-a (ANTX) with ozone, chlorine, chlorine dioxide and permanganate. This kinetic database contains rate constants not previously reported and determined in the present work (e.g. for permanganate oxidation of ANTX and chlorine dioxide oxidation of CYN and ANTX), together with previously published rate constants for the remaining oxidation processes. Second-order rate constants measured in pure aqueous solutions of these toxins could be used in a kinetic model to predict the toxin oxidation efficiency of ozone, chlorine, chlorine dioxide and permanganate when applied to natural waters. Oxidants were applied to water from a eutrophic Swiss lake (Lake Greifensee) in static-dose testing and dynamic time-resolved experiments to confirm predictions from the kinetic database, and to investigate the effects of a natural matrix on toxin oxidation and by-product formation. Overall, permanganate can effectively oxidize ANTX and MC-LR, while chlorine will oxidize CYN and MC-LR and ozone is capable of oxidizing all three toxins with the highest rate. The formation of trihalomethanes (THMs) in the treated water may be a restriction to the application of sufficiently high-chlorine doses.

  18. Electrokinetic-enhanced permanganate delivery and remediation of contaminated low permeability porous media.

    PubMed

    Chowdhury, Ahmed I A; Gerhard, Jason I; Reynolds, David; Sleep, Brent E; O'Carroll, Denis M

    2017-04-15

    Back diffusion of contaminants from low permeability strata has inhibited site remediation and closure due to an inability to deliver remediants into these strata. This study demonstrates the potential of electrokinetics (EK) to significantly reduce back diffusion of chlorinated compounds from low permeability porous media. Experiments were conducted in a two-dimensional sandbox packed with vertical layers of coarse sand and silt contaminated with aqueous trichloroethene (TCE). Three experiments, each approximately 41 days in duration, compared EK-enhanced in situ chemical oxidation (EK-ISCO) to EK or ISCO alone. EK-ISCO successfully delivered the oxidant (permanganate, PM) throughout the silt cross-section while ISCO without EK resulted only in PM delivery to the edges of the silt layer fringes. EK-ISCO resulted in a 4.4-fold reduction in TCE concentrations in the coarse sand compared to a 3.5-fold reduction from ISCO alone. EK-ISCO with a 25 mA current was found to be more effective than with 300 mA current. Overall, this study suggests that electrokinetics coupled with an appropriate in situ remediation technique, such as ISCO, can enhance remediation of lower permeability strata and limit the extent of contaminant back diffusion.

  19. BENCH-SCALE VISUALIZATION OF DNAPL REMEDIATION PROCESSES IN ANALOG HETEROGENEOUS AQUIFERS: SURFACTANT FLOODS, AND IN SITU OXIDATION USING PERMANGANATE

    EPA Science Inventory

    We have conducted well-controlled DNAPL remediation experiments using surfactants (Aerosol MA and Tween 80) to increase solubility and an oxidant (permanganate) to chemically degrade the DNAPL. Photographs and digital image analysis illustrate previously unobserved interactions b...

  20. Oxidation of non-steroidal anti-inflammatory drugs with aqueous permanganate.

    PubMed

    Rodríguez-Álvarez, Tania; Rodil, Rosario; Quintana, José Benito; Triñanes, Sara; Cela, Rafael

    2013-06-01

    Potassium permanganate is a strong oxidant widely used in drinking water treatment, that can react with organic micropollutants. Thus, the oxidation kinetics and transformation route of seven non-steroidal anti-inflammatory drugs (NSAIDs) upon reaction with potassium permanganate was investigated. A liquid chromatography-quadrupole-time-of-flight-mass spectrometry (LC-Q-TOF-MS) system was used to follow the time course of pharmaceuticals concentrations and for the identification of their by-products. Under strong oxidation conditions (2 mg L(-1) KMnO4, 24 h), only two NSAIDs were significantly degraded: indomethacine and diclofenac. The degradation kinetics of these two drugs was investigated at different concentrations of permanganate, chlorides, phosphates and sample pH by means of a full factorial experimental design. Depending on these factors, half-lives were in the range: 2-270 h for indomethacine and 3-558 h for diclofenac, equivalent to apparent second order constants between 0.65 and 9.5 M(-1) s(-1) and 0.27 and 7.4 M(-1) s(-1), respectively. Permanganate concentration was the most significant factor on NSAIDs oxidation kinetics, but the pH also played a significant role in diclofenac reaction, being faster at acidic pH. In the case of indomethacine, the dose of permanganate seemed also to play an autocatalytic effect. The use of an accurate-mass high resolution LC-Q-TOF-MS system permitted the identification of a total of 13 by-products. The transformation path of these drugs consisted mainly of hydroxylations, decarboxylations and oxidation of aromatic double bonds, with ring opening. The software predicted toxicity of these products indicates that they are expected not to be more toxic than the NSAIDs, with the exception of two indomethacine by-products. Reaction in real samples was slower and/or incomplete for both pharmaceuticals, depending on the organic matter content of the sample. However, still all transformation products could be detected for

  1. Enantioselective Oxidation of Alkenes with Potassium Permanganate Catalyzed by Chiral Dicationic Bisguanidinium.

    PubMed

    Wang, Chao; Zong, Lili; Tan, Choon-Hong

    2015-08-26

    Chiral anion-controlled ion-pairing catalysis was demonstrated to be a wide-ranging strategy that can utilize a variety of cationic metal species. In a similar manner, we envision a complementary strategy using chiral cation in partnership with inorganic anionic metal salts. Herein, we report a chiral dicationic bisguanidinium-catalyzed asymmetric oxidation reaction of alkenes with potassium permanganate. Chiral induction is attributed to ion-pairing interaction between chiral cation and enolate anion. The success of the current permanganate oxidation reaction together with mechanistic insights should provide inspiration for expansion to other anionic metal salts and would open up new paradigms for asymmetric transition metal catalysis, phase-transfer catalysis, and ion-pairing catalysis.

  2. Permanganate oxidation of arsenic(III): Reaction stoichiometry and the characterization of solid product

    NASA Astrophysics Data System (ADS)

    Lee, Giehyeon; Song, Kyungsun; Bae, Jongseong

    2011-09-01

    Permanganate (MnO 4-) has widely been used as an effective oxidant for drinking water treatment systems, as well as for in situ treatment of groundwater impacted by various organic contaminants. The reaction stoichiometry of As(III) oxidation by permanganate has been assumed to be 1.5, based on the formation of solid product, which is putatively considered to be MnO 2(s). This study determined the stoichiometric ratio (SR) of the oxidation reaction with varying doses of As(III) (3-300 μM) and MnO 4- (0.5 or 300 μM) under circumneutral pH conditions (pH 4.5-7.5). We also characterized the solid product that was recovered ˜1 min after the oxidation of 2.16 mM As(III) by 0.97 mM MnO 4- at pH 6.9 and examined the feasibility of secondary heterogeneous As(III) oxidation by the solid product. When permanganate was in excess of As(III), the SR of As(III) to Mn(VII) was 2.07 ± 0.07, regardless of the solution pH; however, it increased to 2.49 ± 0.09 when As(III) was in excess. The solid product was analogous to vernadite, a poorly crystalline manganese oxide based on XRD analysis. The average valence of structural Mn in the solid product corresponded to +III according to the splitting interval of the Mn3s peaks (5.5 eV), determined using X-ray photoelectron spectroscopy (XPS). The relative proportions of the structural Mn(IV):Mn(III):Mn(II) were quantified as 19:62:19 by fitting the Mn2p 3/2 spectrum of the solid with the five multiplet binding energy spectra for each Mn valence. Additionally, the O1s spectrum of the solid was comparable to that of Mn-oxide but not of Mn-hydroxide. These results suggest that the solid product resembled a poorly crystalline hydrous Mn-oxide such as (Mn II0.19Mn III0.62Mn IV0.19) 2O 3· nH 2O, in which Mn(II) and Mn(IV) were presumably produced from the disproportionation of aqueous phase Mn(III). Thermodynamic calculations also show that the formation of Mn(III) oxide is more favorable than that of Mn(IV) oxide from As(III) oxidation

  3. Kinetic Study of Colloidal Birnessite Formation During Oxidation of Chlorinated Solvent by Permanganate

    SciTech Connect

    Li, X. David; Schwartz, Franklin W.

    2003-03-26

    The use of permanganate for the in situ oxidation of chlorinated ethylenes has shown promise in the remediation of subsurface contamination. The oxidation reaction produces Mn oxide, which causes pore plugging and problems in oxidant delivery. This study utilized batch experiments to explore the feasibility of using phosphate to slow down the formation of colloidal Mn oxide, which may allow Mn oxide to precipitate further away from the zone of oxidation. The results show that phosphate can influence the formation of the colloids. Colloid growth was slow, especially early in the reaction. The rate of the colloid formation decreases linearly with increasing concentrations of phosphate ion. Efforts were made to elucidate the mechanism of the reaction between phosphate and Mn oxide. A model was proposed to describe the reaction process, which is thought to involve the formation of a Mn(IV)-phosphate complex in the aqueous phase before formation of the colloids.

  4. Kinetic and Mechanistic Aspects of the Reactions of Iodide and Hypoiodous Acid with Permanganate: Oxidation and Disproportionation.

    PubMed

    Zhao, Xiaodan; Salhi, Elisabeth; Liu, Huiling; Ma, Jun; von Gunten, Urs

    2016-04-19

    Oxidation kinetics of iodide and HOI/OI(-) by permanganate were studied in the pH range of 5.0-10.0. Iodide oxidation and iodate formation were faster at lower pH. The apparent second-order rate constants (k(obs)) for iodide oxidation by permanganate decrease with increasing pH from 29 M(-1) s(-1) at pH 5.0 and 6.9 M(-1) s(-1) at pH 7.0 to 2.7 M(-1) s(-1) at pH 10.0. k(obs) for HOI abatement are 56 M(-1) s(-1) at pH 5.0, 2.5 M(-1) s(-1) at pH 7.0, and 173 M(-1) s(-1) at pH 10.0. Iodate yields over HOI abatement decrease from 98% at pH 6.0 to 33% for pH ≥ 9.5, demonstrating that HOI disproportionation dominates HOI transformation by permanganate at pH ≥ 8.0. MnO2 formed as a product from permanganate reduction, oxidizes HOI to iodate for pH < 8.0, and promotes HOI disproportionation for pH ≥ 8.0. The rate of HOI oxidation or disproportionation induced by MnO2 is much lower than for permanganate. During treatment of iodide-containing waters, the potential for iodinated disinfection byproducts (I-DBPs) formation is highest at pH 7.0-8.0 due to the long lifetime of HOI. For pH < 6.0, HOI/I2 is quickly oxidized by permanganate to iodate, whereas for pH ≥ 8.0, HOI/OI(-) undergoes a fast permanganate-mediated disproportionation.

  5. Graphite oxides: effects of permanganate and chlorate oxidants on the oxygen composition.

    PubMed

    Chua, Chun Kiang; Sofer, Zdeněk; Pumera, Martin

    2012-10-15

    Research on graphene materials has refocused on graphite oxides (GOs) in recent years. The fabrication of GO is commonly accomplished by using concentrated sulfuric acid in conjunction with: a) fuming nitric acid and KClO(3) oxidant (Staudenmaier); b) concentrated nitric acid and KClO(3) oxidant (Hofmann); c) sodium nitrate for in situ production of nitric acid in the presence of KMnO(4) (Hummers); or d) concentrated phosphoric acid with KMnO(4) (Tour). These methods have been used interchangeably in the graphene community, since the properties of GOs produced by these different methods were assumed as almost similar. In light of the wide applicability of GOs in nanotechnology applications, in which presence of certain oxygen functional groups are specifically important, the qualities and functionalities of the GOs produced by using these four different methods, side-by-side, was investigated. The structural characterizations of the GOs would be probed by using high resolution X-ray photoelectron spectroscopy, nuclear magnetic resonance, Fourier transform infrared spectroscopy, and Raman spectroscopy. Further electrochemical applicability would be evaluated by using electrochemical impedance spectroscopy and cyclic voltammetry techniques. Our analyses highlighted that the oxidation methods based on permanganate oxidant (Hummers and Tour methods) gave GOs with lower heterogeneous electron-transfer rates and a higher amount of carbonyl and carboxyl functionalities compared with when using chlorate oxidant (Staudenmaier and Hofmann methods). These observations indicated large disparities between the GOs obtained from different oxidation methods. Such insights would provide fundamental knowledge for fine tuning GO for future applications.

  6. Kinetics of the oxidation of cylindrospermopsin and anatoxin-a with chlorine, monochloramine and permanganate.

    PubMed

    Rodríguez, Eva; Sordo, Ana; Metcalf, James S; Acero, Juan L

    2007-05-01

    Cyanobacteria produce toxins that may contaminate drinking water sources. Among others, the presence of the alkaloid toxins cylindrospermopsin (CYN) and anatoxin-a (ANTX) constitutes a considerable threat to human health due to the acute and chronic toxicity of these compounds. In the present study, not previously reported second-order rate constants for the reactions of CYN and ANTX with chlorine and monochloramine and of CYN with potassium permanganate were determined and the influence of pH and temperature was established for the most reactive cases. It was found that the reactivity of CYN with chlorine presents a maximum at pH 7 (rate constant of 1265 M(-1)s(-1)). However, the oxidation of CYN with chloramine and permanganate are rather slow processes, with rate constants <1 M(-1)s(-1). The first chlorination product of CYN was found to be 5-chloro-CYN (5-Cl-CYN), which reacts with chlorine 10-20 times slower than the parent compound. The reactivity of ANTX with chlorine and chloramines is also very low (k<1M(-1)s(-1)). The elimination of CYN and ANTX in surface water was also investigated. A chlorine dose of 1.5 mg l(-1) was enough to oxidize CYN almost completely. However, 3 mg l(-1) of chlorine was able to remove only 8% of ANTX, leading to a total formation of trihalomethanes (TTHM) at a concentration of 150 microg l(-1). Therefore, chlorination is a feasible option for CYN degradation during oxidation and disinfection processes but not for ANTX removal. The permanganate dose required for CYN oxidation is very high and not applicable in waterworks.

  7. Oxidation of antibiotics during water treatment with potassium permanganate: reaction pathways and deactivation.

    PubMed

    Hu, Lanhua; Stemig, Amanda M; Wammer, Kristine H; Strathmann, Timothy J

    2011-04-15

    Recent work demonstrates that three widely administered antibiotics (ciprofloxacin, lincomycin, and trimethoprim) are oxidized by potassium permanganate [KMnO(4), Mn(VII)] under conditions relevant to water treatment operations. However, tests show that little to no mineralization occurs during reactions with Mn(VII), so studies were undertaken to characterize the reaction products and pathways and to assess the effects of Mn(VII)-mediated transformations on the antibacterial activity of solutions. Several oxidation products were identified for each antibiotic by liquid chromatography-tandem mass spectrometry (LC-MS/MS). For ciprofloxacin, 12 products were identified, consistent with oxidation of the tertiary aromatic and secondary aliphatic amine groups on the piperazine ring and the cyclopropyl group. For lincomycin, seven products were identified that indicate structural changes to the pyrrolidine ring and thioether group. For trimethoprim, seven products were identified, consistent with Mn(VII) reaction at C═C double bonds on the pyrimidine ring and the bridging methylene group. Oxidation pathways are proposed based on the identified products. Bacterial growth inhibition bioassays (E. coli DH5α) show that the mixture of products resulting from Mn(VII) reactions with the antibiotics collectively retain negligible antibacterial potency in comparison to the parent antibiotics. These results suggest that permanganate can be an effective reagent for eliminating the pharmaceutical activity of selected micropollutants during drinking water treatment.

  8. Mercury oxidation and adsorption characteristics of potassium permanganate modified lignite semi-coke.

    PubMed

    Zhang, Huawei; Chen, Jitao; Liang, Peng; Wang, Li

    2012-01-01

    The adsorption characteristics of virgin and potassium permanganate modified lignite semi-coke (SC) for gaseous Hg0 were investigated in an attempt to produce more effective and lower price adsorbents for the control of elemental mercury emission. Brunauer-Emmett-Teller (BET) measurements, X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to analyze the surface physical and chemical properties of SC, Mn-SC and Mn-H-SC before and after mercury adsorption. The results indicated that potassium permanganate modification had significant influence on the properties of semi-coke, such as the specific surface area, pore structure and surface chemical functional groups. The mercury adsorption efficiency of modified semi-coke was lower than that of SC at low temperature, but much higher at high temperature. Amorphous Mn7+, Mn6+ and Mn4+ on the surface of Mn-SC and Mn-H-SC were the active sites for oxidation and adsorption of gaseous Hg0, which oxidized the elemental mercury into Hg2+ and captured it. Thermal treatment reduced the average oxidation degree of Mn(x+) on the surface of Mn-SC from 3.80 to 3.46. However, due to the formation of amorphous MnOx, the surface oxidation active sites for gaseous Hg0 increased, which gave Mn-H-SC higher mercury adsorption efficiency than that of Mn-SC at high temperature.

  9. Enhanced Delivery of Permanganate Using a Manganese Dioxide Particle Stabilization Aid

    NASA Astrophysics Data System (ADS)

    Crimi, M.; Quickel, M.; Ko, S.

    2008-12-01

    Manganese dioxide (MnO2) particles are products of permanganate reactions that have the potential to deposit in the subsurface and impact flow around areas of high contaminant saturation. Control of these particles can improve oxidant injection and transport as well as the contact between the oxidant and contaminants of concern. Four stabilization aids were evaluated in batch experiments for their ability to stabilize particles in solution over time and a range of groundwater conditions. The stabilization aid sodium hexametaphosphate (SHMP) demonstrated the most promising results - it inhibited particle settling, provided for greater particle stability, and resulted in particles of a smaller average size over a range of pH, particle concentration, ionic content/strength, and oxidation/reduction potential (ORP) conditions. Column transport studies were then conducted to evaluate the impact of including SHMP with delivery of permanganate to a nonaqueous phase liquid (NAPL) source zone within four different media types. While particle retention and transport varied with specific media type, SHMP consistently provided for significantly decreased particle retention and improved flow. With SHMP, particle retention directly in the NAPL source zone decreased by 25% in sand media, 53% in sand + clay media, 85% in sand + goethite media, and 47% sand + organic carbon media.

  10. Formation of iodinated disinfection by-products during oxidation of iodide-containing water with potassium permanganate.

    PubMed

    Ye, Tao; Xu, Bin; Lin, Yi-Li; Hu, Chen-Yan; Xia, Sheng-Ji; Lin, Lin; Mwakagenda, Seleli Andrew; Gao, Nai-Yun

    2012-11-30

    This study shows that iodinated disinfection by-products (I-DBPs) including iodoform (IF), iodoacetic acid (IAA) and triiodoacetic acid (TIAA) can be produced when iodide-containing waters are in contact with potassium permanganate. IF was found as the major I-DBP species during the oxidation. Iodide was oxidized to HOI, I(2) and I(3)(-), consequently, which led to the formation of iodinated organic compounds. I-DBPs varied with reaction time, solution pH, initial concentrations of iodide and potassium permanganate. Yields of IF, IAA and TIAA increased with reaction time and considerable I-DBPs were formed within 12 h. Peak IF yields were found at circumneutral pH range. However, formation of IAA and TIAA was favored under acidic conditions. Molar ratio of iodide to potassium permanganate showed significant influence on formation of IF, IAA and TIAA. The formation of IF, IAA and TIAA also depended on the characteristics of the waters.

  11. Evaluation of the kinetic oxidation of aqueous volatile organic compounds by permanganate.

    PubMed

    Mahmoodlu, Mojtaba G; Hassanizadeh, S Majid; Hartog, Niels

    2014-07-01

    The use of permanganate solutions for in-situ chemical oxidation (ISCO) is a well-established groundwater remediation technology, particularly for targeting chlorinated ethenes. The kinetics of oxidation reactions is an important ISCO remediation design aspect that affects the efficiency and oxidant persistence. The overall rate of the ISCO reaction between oxidant and contaminant is typically described using a second-order kinetic model while the second-order rate constant is determined experimentally by means of a pseudo first order approach. However, earlier studies of chlorinated hydrocarbons have yielded a wide range of values for the second-order rate constants. Also, there is limited insight in the kinetics of permanganate reactions with fuel-derived groundwater contaminants such as toluene and ethanol. In this study, batch experiments were carried out to investigate and compare the oxidation kinetics of aqueous trichloroethylene (TCE), ethanol, and toluene in an aqueous potassium permanganate solution. The overall second-order rate constants were determined directly by fitting a second-order model to the data, instead of typically using the pseudo-first-order approach. The second-order reaction rate constants (M(-1) s(-1)) for TCE, toluene, and ethanol were 8.0×10(-1), 2.5×10(-4), and 6.5×10(-4), respectively. Results showed that the inappropriate use of the pseudo-first-order approach in several previous studies produced biased estimates of the second-order rate constants. In our study, this error was expressed as a function of the extent (P/N) in which the reactant concentrations deviated from the stoichiometric ratio of each oxidation reaction. The error associated with the inappropriate use of the pseudo-first-order approach is negatively correlated with the P/N ratio and reached up to 25% of the estimated second-order rate constant in some previous studies of TCE oxidation. Based on our results, a similar relation is valid for the other volatile

  12. Oxidation of cefazolin by potassium permanganate: Transformation products and plausible pathways.

    PubMed

    Li, Liping; Wei, Dongbin; Wei, Guohua; Du, Yuguo

    2016-04-01

    Cefazolin was demonstrated to exert high reactivity toward permanganate (Mn(VII)), a common oxidant in water pre-oxidation treatment. In this study, five transformation products were found to be classified into three categories according to the contained characteristic functional groups: three (di-)sulfoxide products, one sulfone product and one di-ketone product. Products analyses showed that two kinds of reactions including oxidation of thioether and the cleavage of unsaturated CC double bond occurred during transformation of cefazolin by Mn(VII). Subsequently, the plausible transformation pathways under different pH conditions were proposed based on the identified products and chemical reaction principles. More importantly, the simulation with real surface water matrix indicated that the proposed transformation pathways of cefazolin could be replayed in real water treatment practices. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Preparation of anionic clay-birnessite manganese oxide composites by interlayer oxidation of oxalate ions by permanganate

    SciTech Connect

    Arulraj, James; Rajamathi, Michael

    2013-02-15

    Oxalate intercalated anionic clay-like nickel zinc hydroxysalt was obtained starting from nickel zinc hydroxyacetate, Ni{sub 3}Zn{sub 2}(OH){sub 8}(OAc){sub 2}{center_dot}2H{sub 2}O, by anion exchange. The intercalated oxalate species was reacted with potassium permanganate in such a way that the layered manganese oxide formed was within the interlayer region of the anionic clay resulting in a layered composite in which the negative charges on the birnessite type manganese oxide layers compensate the positive charges on the anionic clay layers. Birnessite to anionic clay ratio could be varied by varying the reaction time or the amount of potassium permanganate used. - Graphical abstract: Nickel zinc hydroxyoxalate was reacted with potassium permanganate to get nickel zinc hydroxide birnessite composites in which the positive charges on the hydroxide layers are neutralized by the negative charges on birnessite layers. Highlights: Black-Right-Pointing-Pointer Anionic and cationic layered solid composites prepared. Black-Right-Pointing-Pointer Ni-Zn hydroxyoxalate reacted with KMnO{sub 4} to deposit MnO{sub 2} in the interlayer. Black-Right-Pointing-Pointer Birnessite layers coexist with anionic clay layers in the composites. Black-Right-Pointing-Pointer Birnessite/anionic clay ratio controlled by amount of KMnO{sub 4} used and reaction time.

  14. Conventional oxidation treatments for the removal of arsenic with chlorine dioxide, hypochlorite, potassium permanganate and monochloramine.

    PubMed

    Sorlini, Sabrina; Gialdini, Francesca

    2010-11-01

    Arsenic is widespread in soils, water and air. In natural water the main forms are arsenite (As(III)) and arsenate (As(V)). The consumption of water containing high concentration of arsenic produces serious effects on human health, like skin and lung cancer. In Italy, Legislative Decree 2001/31 reduced the limit of arsenic from 50 to 10 μg/L, in agreement with the European Directive 98/83/EC. As consequence, many drinking water treatment plant companies needed to upgrade the existing plants where arsenic was previously removed or to build up new plants for arsenic removal when this contaminant was not previously a critical parameter. Arsenic removal from water may occur through the precipitation with iron or aluminum salts, adsorption on iron hydroxide or granular activated alumina (AA), reverse osmosis and ion exchange (IE). Some of the above techniques, especially precipitation, adsorption with AA and IE, can reach good arsenic removal yields only if arsenic is oxidized. The aim of the present work is to investigate the efficiency of the oxidation of As(III) by means of four conventional oxidants (chlorine dioxide, sodium hypochlorite, potassium permanganate and monochloramine) with different test conditions: different type of water (demineralised and real water), different pH values (5.7-6-7 and 8) and different doses of chemicals. The arsenic oxidation yields were excellent with potassium permanganate, very good with hypochlorite and low with monochloramine. These results were observed both on demineralised and real water for all the tested reagents with the exception of chlorine dioxide that showed a better arsenic oxidation on real groundwater than demineralised water.

  15. The Oxidation of Terminal Alkenes by Permanganate: A Practical Demonstration of the Use of Phase Transfer Agents.

    ERIC Educational Resources Information Center

    Brown, Keith C.; And Others

    1982-01-01

    Use of phase transfer agents to facilitate/accelerate chemical reactions has become an established practice, particularly in organic chemistry. Describes an undergraduate laboratory procedure demonstrating the principles involved in the use of said agents. Includes student results from phase transfer assisted permanganate oxidations. (Author/JN)

  16. Analysis of sources of bulk conductivity change in saturated silica sand after unbuffered TCE oxidation by permanganate.

    PubMed

    Hort, Ryan D; Revil, André; Munakata-Marr, Junko

    2014-09-01

    Time lapse resistivity surveys could potentially improve monitoring of permanganate-based in situ chemical oxidation (ISCO) of organic contaminants such as trichloroethene (TCE) by tracking changes in subsurface conductivity that result from injection of permanganate and oxidation of the contaminant. Bulk conductivity and pore fluid conductivity changes during unbuffered TCE oxidation using permanganate are examined through laboratory measurements and conductivity modeling using PHREEQC in fluid samples and porous media samples containing silica sand. In fluid samples, oxidation of one TCE molecule produces three chloride ions and one proton, resulting in an increase in fluid electrical conductivity despite the loss of two permanganate ions in the reaction. However, in saturated sand samples in which up to 8mM TCE was oxidized, at least 94% of the fluid conductivity associated with the presence of protons was removed within 3h of sand contact, most likely through protonation of silanol groups found on the surface of the sand grains. Minor conductivity effects most likely associated with pH-dependent reductive dissolution of manganese dioxide were also observed but not accounted for in pore-fluid conductivity modeling. Unaccounted conductivity effects resulted in an under-calculation of post-reaction pore fluid conductivity of 2.1% to 5.5%. Although small increases in the porous media formation factor resulting from precipitation of manganese dioxide were detected (about 3%), these increases could not be confirmed to be statistically significant. Both injection of permanganate and oxidation of TCE cause increases in bulk conductivity that would be detectable through time-lapse resistivity surveys in field conditions.

  17. Analysis of sources of bulk conductivity change in saturated silica sand after unbuffered TCE oxidation by permanganate

    NASA Astrophysics Data System (ADS)

    Hort, Ryan D.; Revil, André; Munakata-Marr, Junko

    2014-09-01

    Time lapse resistivity surveys could potentially improve monitoring of permanganate-based in situ chemical oxidation (ISCO) of organic contaminants such as trichloroethene (TCE) by tracking changes in subsurface conductivity that result from injection of permanganate and oxidation of the contaminant. Bulk conductivity and pore fluid conductivity changes during unbuffered TCE oxidation using permanganate are examined through laboratory measurements and conductivity modeling using PHREEQC in fluid samples and porous media samples containing silica sand. In fluid samples, oxidation of one TCE molecule produces three chloride ions and one proton, resulting in an increase in fluid electrical conductivity despite the loss of two permanganate ions in the reaction. However, in saturated sand samples in which up to 8 mM TCE was oxidized, at least 94% of the fluid conductivity associated with the presence of protons was removed within 3 h of sand contact, most likely through protonation of silanol groups found on the surface of the sand grains. Minor conductivity effects most likely associated with pH-dependent reductive dissolution of manganese dioxide were also observed but not accounted for in pore-fluid conductivity modeling. Unaccounted conductivity effects resulted in an under-calculation of post-reaction pore fluid conductivity of 2.1% to 5.5%. Although small increases in the porous media formation factor resulting from precipitation of manganese dioxide were detected (about 3%), these increases could not be confirmed to be statistically significant. Both injection of permanganate and oxidation of TCE cause increases in bulk conductivity that would be detectable through time-lapse resistivity surveys in field conditions.

  18. Evaluation of the oxidation of enrofloxacin by permanganate and the antimicrobial activity of the products.

    PubMed

    Xu, Yongpeng; Liu, Shiyao; Guo, Fang; Zhang, Bo

    2016-02-01

    Permanganate [Mn(VII)] oxidation of the fluoroquinolone (FQ) antibiotic enrofloxacin (ENR) was investigated with respect to kinetics and mechanisms, and the products were evaluated for residual antibacterial activity. The degradation of ENR by Mn(VII) obeyed second-order kinetics. A modern liquid chromatography coupled to a hybrid quadrupole time-of-flight mass spectrometer (LC-Q-TOF) was used to determine the accurate mass of the measured degradation products. The structures of nine oxidation products were identified at a neutral pH, one of which was an N-oxide product formed from the oxidation of tertiary amines. One proposed plausible reaction pathway was that the oxidation occurred on the piperazine ring; the C-H adjacent to the amine group was attacked by Mn(VII). The identified products from ENR arose through four pathways involving two mechanisms of N-dealkylation, C-hydroxylation and the reactions of amine oxides. The quinolone core remained intact for all of the products. The residual antibacterial activity of the oxidative reaction byproducts against the nonresistant Escherichia coli (G(-)) reference strain DH5ɑ was evaluated by quantifying the bacterial colonies. The oxidation products exhibited reduced antibacterial activity compared with their parent compound. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Gold nanorods-enhanced rhodamine B-permanganate chemiluminescence and its analytical application

    NASA Astrophysics Data System (ADS)

    Hassanzadeh, Javad; Amjadi, Mohammad; Manzoori, Jamshid L.; Sorouraddin, Mohammad Hossein

    2013-04-01

    A novel enhanced chemiluminescence system was developed by applying gold nanorods (Au NRs) as catalysts in rhodamine B-permanganate reaction. Au NRs with three different aspect ratios were synthesized by seed mediated growth method and characterized by UV-Vis spectra and transmission electron microscopy. It was demonstrated that Au NRs have much higher catalytic effect than spherical nanoparticles on rhodamine B-permanganate chemiluminescence reaction. Among various sizes of Au NRs, those with average aspect ratio of 3.0 were found to have the most remarkable catalytic activity. As an analytical application of the new chemiluminescence system, albumin as a model protein was quantified based on its interaction with NRs. Albumin binds to Au NRs active surfaces and inhibits their catalytic action and therefore decreases the intensity of chemiluminescence. This diminution effect is linearly related to the concentration of the human and bovine serum albumin over the ranges of 0.45-90 and 0.75-123 nmol L-1, respectively with the corresponding limits of detection of 0.18 and 0.30 nmol L-1. The method was successfully applied to the determination of albumin in human and bovine serum samples.

  20. Treatability assessment of polycyclic aromatic hydrocarbons contaminated marine sediments using permanganate, persulfate and Fenton oxidation processes.

    PubMed

    Shih, Yu-Jen; Binh, Nguyen Thanh; Chen, Chiu-Wen; Chen, Chih-Feng; Dong, Cheng-Di

    2016-05-01

    Various chemical oxidation techniques, such as potassium permanganate (KMnO4), sodium persulfate (Na2S2O8), Fenton (H2O2/Fe(2+)), and the modified persulfate and Fenton reagents (activated by ferrous complexes), were carried out to treat marine sediments that were contaminated with polycyclic aromatic hydrocarbons (PAHs) and dredged from Kaohsiung Harbor in Taiwan. Experimental results revealed that KMnO4 was the most effective of the tested oxidants in PAH degradation. Owing to the high organic matter content in the sediment that reduced the efficiencies of Na2S2O8 and regular Fenton reactions, a large excess of oxidant was required. Nevertheless, KH2PO4, Na4P2O7 and four chelating agents (EDTA, sodium citrate, oxalic acid, and sodium oxalate) were utilized to stabilize Fe(II) in activating the Na2S2O8 and Fenton oxidations, while Fe(II)-citrate remarkably promoted the PAH degradation. Increasing the molecular weight and number of rings of PAH did not affect the overall removal efficiencies. The correlation between the effectiveness of the oxidation processes and the physicochemical properties of individual PAH was statistically analyzed. The data implied that the reactivity of PAH (electron affinity and ionization potential) affected its treatability more than did its hydrophobicity (Kow, Koc and Sw), particularly using experimental conditions under which PAHs could be effectively oxidized.

  1. A comparison of iodinated trihalomethane formation from chlorine, chlorine dioxide and potassium permanganate oxidation processes.

    PubMed

    Zhang, Tian-Yang; Xu, Bin; Hu, Chen-Yan; Lin, Yi-Li; Lin, Lin; Ye, Tao; Tian, Fu-Xiang

    2015-01-01

    This study compared the formation of iodinated trihalomethanes (I-THMs) from iodide-containing raw waters oxidized by chlorine, chlorine dioxide (ClO₂) and potassium permanganate (KMnO₄) at different oxidant concentrations, reaction times, pHs, initial iodide concentrations and bromide to iodide mass ratios. Among the six investigated I-THMs, iodoform was the major species formed during the oxidation using chlorine, ClO₂ and KMnO₄. When oxidant concentration increased from 0.1 to 3.0 mg/L, the formation of I-THMs increased and then decreased for chlorine and ClO₂, but kept increasing for KMnO₄. As the reaction time went by, I-THM concentration increased to a plateau within 10 h (ClO₂ within only 1 h, especially) for all the three oxidants. I-THM formation gradually increased from pH 3.0 to 9.0 and remained stable at pH values higher than 7.5 for chlorine; however, for ClO₂ and KMnO₄ the highest I-THM formation showed at pH 7.0 and 7.5, respectively. As initial iodide concentration increased from 20 to 800 μg/L, the total amount and species of I-THMs increased for the three oxidants. Iodide contributed to I-THM formation much more significantly than bromide.

  2. Oxidative degradation of triclosan by potassium permanganate: Kinetics, degradation products, reaction mechanism, and toxicity evaluation.

    PubMed

    Chen, Jing; Qu, Ruijuan; Pan, Xiaoxue; Wang, Zunyao

    2016-10-15

    In this study, we systematically investigated the potential applicability of potassium permanganate for removal of triclosan (TCS) in water treatment. A series of kinetic experiments were carried out to study the influence of various factors, including the pH, oxidant doses, temperature, and presence of typical anions (Cl(-), SO4(2-), NO3(-)), humic acid (HA), and fulvic acid (FA) on triclosan removal. The optimal reaction conditions were: pH = 8.0, [TCS]0:[KMnO4]0 = 1:2.5, and T = 25 °C, where 20 mg/L of TCS could be completely degraded in 120 s. However, the rate of TCS (20 μg/L) oxidation by KMnO4 ([TCS]0:[KMnO4]0 = 1:2.5) was 1.64 × 10(-3) mg L(-1)·h(-1), lower than that at an initial concentration of 20 mg/L (2.24 × 10(3) mg L(-1)·h(-1)). A total of eleven products were detected by liquid chromatography-quadrupole-time-of-flight-mass spectrometry (LC-Q-TOF-MS) analysis, including phenol and its derivatives, benzoquinone, an organic acid, and aldehyde. Two main reaction pathways involving CO bond cleavage (-C(8)O(7)-) and benzene ring opening (in the less chlorinated benzene ring) were proposed, and were further confirmed based on frontier electron density calculations and point charges. Furthermore, the changes in the toxicity of the reaction solution during TCS oxidation by KMnO4 were evaluated by using both the luminescent bacteria Photobacterium phosphoreum and the water flea Daphnia magna. The toxicity of 20 mg/L triclosan to D. magna and P. phosphoreum after 60 min was reduced by 95.2% and 43.0%, respectively. Phenol and 1,4-benzoquinone, the two representative degradation products formed during permanganate oxidation, would yield low concentrations of DBPs (STHMFP, 20.99-278.97 μg/mg; SHAAFP, 7.86 × 10(-4)-45.77 μg/mg) after chlorination and chloramination. Overall, KMnO4 can be used as an effective oxidizing agent for TCS removal in water and wastewater treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Formation of assimilable organic carbon during oxidation of natural waters with ozone, chlorine dioxide, chlorine, permanganate, and ferrate.

    PubMed

    Ramseier, Maaike K; Peter, Andreas; Traber, Jacqueline; von Gunten, Urs

    2011-02-01

    Five oxidants, ozone, chlorine dioxide, chlorine, permanganate, and ferrate were studied with regard to the formation of assimilable organic carbon (AOC) and oxalate in absence and presence of cyanobacteria in lake water matrices. Ozone and ferrate formed significant amounts of AOC, i.e. more than 100 μg/L AOC were formed with 4.6 mg/L ozone and ferrate in water with 3.8 mg/L dissolved organic carbon. In the same water samples chlorine dioxide, chlorine, and permanganate produced no or only limited AOC. When cyanobacterial cells (Aphanizomenon gracile) were added to the water, an AOC increase was detected with ozone, permanganate, and ferrate, probably due to cell lysis. This was confirmed by the increase of extracellular geosmin, a substance found in the selected cyanobacterial cells. AOC formation by chlorine and chlorine dioxide was not affected by the presence of the cells. The formation of oxalate upon oxidation was found to be a linear function of the oxidant consumption for all five oxidants. The following molar yields were measured in three different water matrices based on oxidant consumed: 2.4-4.4% for ozone, 1.0-2.8% for chlorine dioxide and chlorine, 1.1-1.2% for ferrate, and 11-16% for permanganate. Furthermore, oxalate was formed in similar concentrations as trihalomethanes during chlorination (yield ∼ 1% based on chlorine consumed). Oxalate formation kinetics and stoichiometry did not correspond to the AOC formation. Therefore, oxalate cannot be used as a surrogate for AOC formation during oxidative water treatment.

  4. Novel sequential process for enhanced dye synergistic degradation based on nano zero-valent iron and potassium permanganate.

    PubMed

    Wang, Xiangyu; Liu, Peng; Fu, Minglai; Ma, Jun; Ning, Ping

    2016-07-01

    A novel synergistic technology based on nano zero-valent iron (NZVI) and potassium permanganate (KMnO4) was developed for treatment of dye wastewater. The synergistic technology was significantly superior, where above 99% of methylene blue (MB) was removed, comparatively, removal efficiencies of MB with the sole technology of NZVI and KMnO4 at pH 6.39 being 52.9% and 63.1%, respectively. The advantages of this technology include (1) the in situ formed materials (manganese (hydr)oxides, iron hydroxides and MnFe oxide), resulting in the stable and high removal efficiency of MB and (2) high removal capacity in a wide range of pH value. Compared with simultaneous addition system of NZVI and KMnO4, MB removal was remarkably improved by sequential addition system, especially when KMnO4 addition time was optimized at 20 min. Analyses of crystal structure (XRD), morphological difference (FE-SEM), element valence and chemical groups (XPS) of NZVI before and after reaction had confirmed the formation of in situ materials, which obviously enhanced removal of MB by oxidation and adsorption. More importantly, the roles of in situ formed materials and degradation mechanism were innovatively investigated, and the results suggested that NCH3 bond of MB molecule was attacked by oxidants (KMnO4 and in situ manganese (hydr)oxides) at position C1 and C9, resulting in cleavage of chromophore. This study provides new insights about an applicable technology for treatment of dye wastewater.

  5. Oxidation of phenolic endocrine disrupting chemicals by potassium permanganate in synthetic and real waters.

    PubMed

    Jiang, Jin; Pang, Su-Yan; Ma, Jun; Liu, Huiling

    2012-02-07

    In this study, five selected environmentally relevant phenolic endocrine disrupting chemicals (EDCs), estrone, 17β-estradiol, estriol, 17α-ethinylestradiol, and 4-n-nonylphenol, were shown to exhibit similarly appreciable reactivity toward potassium permanganate [Mn(VII)] with a second-order rate constant at near neutral pH comparable to those of ferrate(VI) and chlorine but much lower than that of ozone. In comparison with these oxidants, however, Mn(VII) was much more effective for the oxidative removal of these EDCs in real waters, mainly due to the relatively high stability of Mn(VII) therein. Mn(VII) concentrations at low micromolar range were determined by an ABTS [2,2-azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid diammonium] spectrophotometric method based on the stoichiometric reaction of Mn(VII) with ABTS [Mn(VII) + 5ABTS → Mn(II) + 5ABTS(•+)] forming a stable green radical cation (ABTS(•+)). Identification of oxidation products suggested the initial attack of Mn(VII) at the hydroxyl group in the aromatic ring of EDCs, leading to a series of quinone-like and ring-opening products. The background matrices of real waters as well as selected model ligands including phosphate, pyrophosphate, NTA, and humic acid were found to accelerate the oxidation dynamics of these EDCs by Mn(VII). This was explained by the effect of in situ formed dissolved Mn(III), which could readily oxidize these EDCs but would disproportionate spontaneously without stabilizing agents.

  6. UV-visible spectral identification of the solution-phase and solid-phase permanganate oxidation reactions of thymine acetic acid.

    PubMed

    Bui, Chinh T; Sam, Lien A; Cotton, Richard G H

    2004-03-08

    Solution-phase and solid-phase permanganate oxidation reactions of thymine acetic acid were investigated by spectroscopy. The spectral data showed the formation of a stable organomanganese intermediate, which was responsible for the rise in the absorbance at 420 nm. This result enables unambiguous interpretation of the absorbance change at 420 nm, as the intermediate permanganate ions could be isolated on the solid supports.

  7. UV-Vis spectrophotometric studies of self-oxidation/dissociation of quaternary ammonium permanganates (QAP) - impact of solvent polarity

    NASA Astrophysics Data System (ADS)

    Bank, Suraj Prakash; Guru, Partha Sarathi; Dash, Sukalyan

    2015-05-01

    Self-oxidation/dissociation of some quaternary ammonium permanganates (QAPs), such as cetyltrimethylammonium permanganate (CTAP) and tetrabutylammonium permanganate (TBAP), have been studied spectrophotometrically in six different organic solvent media of different polarities wherein the compounds show good solubility and stability. The optical densities of the substrates at zero time (ODo) and first-order rate constants of dissociation (k1) have been determined from their successive scanning for 40 min. At comparable experimental conditions, absorption capabilities of the substrates are compared from the ODo values in various organic media; the stability of the solutions is compared from the successive scan spectra in those media. The ODo values and the k1 values have been plotted against some solvent parameters to understand their effects on the absorbance and reactivity of the QAPs. These data are also subjected to multiple regression analysis to explain the influence of various solvent parameters on the ion-pairing properties of the substrates, thus elucidating their effects on the process of self-oxidation/dissociation of the substrates.

  8. UV-Vis spectrophotometric studies of self-oxidation/dissociation of quaternary ammonium permanganates (QAP) - impact of solvent polarity.

    PubMed

    Bank, Suraj Prakash; Guru, Partha Sarathi; Dash, Sukalyan

    2015-05-05

    Self-oxidation/dissociation of some quaternary ammonium permanganates (QAPs), such as cetyltrimethylammonium permanganate (CTAP) and tetrabutylammonium permanganate (TBAP), have been studied spectrophotometrically in six different organic solvent media of different polarities wherein the compounds show good solubility and stability. The optical densities of the substrates at zero time (ODo) and first-order rate constants of dissociation (k1) have been determined from their successive scanning for 40min. At comparable experimental conditions, absorption capabilities of the substrates are compared from the ODo values in various organic media; the stability of the solutions is compared from the successive scan spectra in those media. The ODo values and the k1 values have been plotted against some solvent parameters to understand their effects on the absorbance and reactivity of the QAPs. These data are also subjected to multiple regression analysis to explain the influence of various solvent parameters on the ion-pairing properties of the substrates, thus elucidating their effects on the process of self-oxidation/dissociation of the substrates.

  9. Destruction efficiencies and dynamics of reaction fronts associated with the permanganate oxidation of trichloroethylene.

    PubMed

    Lee, Eung Seok; Seol, Yongkoo; Fang, Y C; Schwartz, Franklin W

    2003-06-01

    Although potassium permanganate (KMnO4) flushing is commonly used to destroy chlorinated solvents in groundwater, many of the problems associated with this treatment scheme have not been examined in detail. We conducted a KMnO4 flushing experiment in a large sand-filled flow tank (L x W x D = 180 cm x 60 cm x 90 cm) to remove TCE emplaced as a DNAPL in a source zone. The study was specifically designed to investigate cleanup progress and problems of pore plugging associated with the dynamics of the solid-phase reaction front (i.e., MnO2) using chemical and optical monitoring techniques. Ambient flow through the source zone formed a plume of dissolved TCE across the flow tank. The volume and concentration of TCE plume diminished with time because of the in situ oxidation of the DNAPL source. The migration velocity of the MnO2 reaction front decreased with time, suggesting that the kinetics of the DNAPL oxidation process became diffusion-controlled because of the pore plugging. A mass balance calculation indicated that only approximately 18% of the total applied KMnO4 (MnO4- = 1250 mg/ L) participated in the oxidation reaction to destroy approximately 41% of emplaced TCE. Evidently, the efficiency of KMnO4 flushing scheme diminished with time due to pore plugging by MnO2 and likely CO2, particularly in the TCE source zone. In addition, the excess KMnO4 used for flushing may cause secondary aquifer contamination. One needs to be concerned about the efficacy of KMnO4 flushing in the field applications. Development of a new approach that can provide both contaminant destruction and plugging/ MnO4- control is required.

  10. Examining the Critical Roles of Protons in Facilitating Oxidation of Chloride Ions by Permanganates: A Cluster Model Study

    SciTech Connect

    Zhang, Jian; Sun, Zhenrong; Wang, Xue B.

    2015-06-18

    The oxidation power of permanganates (MnO4–) is known to be strongly dependent on pH values, and is greatly enhanced in acidic solutions, in which, for example, MnO4– can even oxidize Cl– ions to produce Cl2 molecules. Although such dependence has been ascribed due to the different reduced states of Mn affordable in different pH media, a molecular level understanding and characterization of initial redox pair complexes available in different pH solutions is very limited. Herein, we report a comparative study of [MnO4]– and [MnO4•Sol]– (Sol = H2O, KCl, and HCl) anion clusters by negative ion photoelectron spectroscopy (NIPES) and theoretical computations to probe chemical bonding and electronic structures of [MnO4•Sol]– clusters, aimed to obtain a microscopic understanding of how MnO4– interacts with surrounding molecules. Our study shows that H2O behaves as a solvent molecule, KCl is a spectator bound by pure electrostatic interactions, both of which do not influence the MnO4– identity in their respective clusters. In contrast, in [MnO4•HCl]–, the proton is found to interact with both MnO4– and Cl– with appreciable covalent characters, and the frontier MOs of the cluster are comprised of contributions from both MnO4– and Cl– moieties. Therefore the proton serves as a chemical bridge, bringing two negatively charged redox species together to form an intimate redox pair. By adding more H+ to MnO4–, the oxygen atom can be taken away in the form of a water molecule, leaving MnO4– as an electron deficient MnO3+ species, which can subsequently oxidize Cl– ions.

  11. To postpone the precipitation of manganese oxides in the degradation of tetrachloroethylene by controlling the permanganate concentration.

    PubMed

    Yang, Weiwei; Qiu, Zhaofu; Zhao, Zhexuan; Lu, Shuguang; Sui, Qian; Gu, Xiaogang

    2017-01-01

    Controlled-release permanganate (CRP) is a relatively new technology used to treat contaminated groundwater. This study tested the encapsulation of permanganate using stearic acid to realize controlled-release properties. Batch experiments were conducted to investigate the performance of manganese oxides (MnO2) in the reaction between CRP and the contaminant of interest: tetrachloroethylene (PCE). The results showed that higher ionic strengths (I = 0.1 mol/L) cause earlier precipitation of MnO2 colloids. Using CRP to degrade PCE could decrease the amount of MnO2 colloids produced and postpone precipitation compared to raw potassium permanganate (KMnO4) under high ionic strength conditions by controlling the KMnO4 concentration in the solution. The amount of MnO2 colloids produced and the time of precipitation depended more on the CRP grain size than on the CRP mass ratio. Controlling the KMnO4 concentration used in the reaction could control the formation of MnO2 precipitates in the premise of guarantee the removal rate of PCE.

  12. Oxidation of flame retardant tetrabromobisphenol a by aqueous permanganate: reaction kinetics, brominated products, and pathways.

    PubMed

    Pang, Su-Yan; Jiang, Jin; Gao, Yuan; Zhou, Yang; Huangfu, Xiaoliu; Liu, Yongze; Ma, Jun

    2014-01-01

    In this work, the most widely used brominated flame retardant tetrabromobisphenol A (TBrBPA) was shown to exhibit appreciable reactivity toward potassium permanganate [Mn(VII)] in water over a wide pH range of 5-10 with the maxima of second-order rate constants (kMn(VII) = 15-700 M(-1) s(-1)) at pH near its pKa values (7.5/8.5). A novel precursor ion scan (PIS) approach using negative electrospray ionization-triple quadrupole mass spectrometry (ESI-QqQMS) was adopted and further optimized for fast selective detection of brominated oxidation products of TBrBPA by Mn(VII). By setting PIS of m/z 79 and 81, two major products (i.e., 4-(2-hydroxyisopropyl)-2,6-dibromophenol and 4-isopropylene-2,6-dibromophenol) and five minor ones (including 2,6-dibromophenol, 2,6-dibromo-1,4-benzoquinone, and three dimers) were detected and suggested with chemical structures from their product ion spectra and bromine isotope patterns. Reaction pathways mainly involving the initial one-electron oxidation of TBrBPA and subsequent release and further reactions of 2,6-dibromo-4-isopropylphenol carbocation intermediate were proposed. The effectiveness of Mn(VII) for treatment of TBrBPA in real waters was confirmed. It is important to better understand the reactivity and toxicity of primary brominated products before Mn(VII) can be applied for treatment of TBrBPA-contaminated wastewater and source water.

  13. Elimination of microcystin-LR and residual Mn species using permanganate and powdered activated carbon: Oxidation products and pathways.

    PubMed

    Jeong, Boyoung; Oh, Min-Seok; Park, Hyun-Mee; Park, Chanhyuk; Kim, Eun-Ju; Hong, Seok Won

    2017-05-01

    The oxidation of microcystin-LR (MC-LR) in deionized water (DI) and river water using potassium permanganate (KMnO4) at a neutral pH and at 23 ± 2 °C was investigated. These two aqueous systems (i.e., DI and river water) gave comparable second-order rate constants (289.9 and 285.5 M(-1)s(-1) (r(2) > 0.99), respectively), which confirmed the effectiveness of this oxidation process for the treatment of natural surface water. The presence of either humic or fulvic acid reduced the removal efficiency of MC-LR, with the latter exhibiting a greater inhibitory effect. Monitoring of MC-LR and residual Mn(2+) levels with adding KMnO4 (1 mg/L) and powdered activated carbon (PAC, 5-20 mg L(-1)) before and during coagulation, respectively, revealed that 60 min of permanganate pre-oxidation followed by coagulant addition with PAC was the most effective approach for reducing both levels below limits stated by WHO guidelines. The MC-LR degradation products were the result of oxidation occurring at the diene and aromatic moieties of the Adda (3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid) side-chain, in addition to amine bond hydrolysis of the Mdha (N-methyldehydroalanine) moiety. Several toxic by-products with an intact Adda chain were observed during the reaction, but completely disappeared after 60 min. This further supports the conclusion that sufficient contact time with permanganate (i.e., >60 min) is essential to reducing the residual toxicity and maximizing the efficiency of MC-LR oxidation when treating raw water.

  14. Transport with Bimolecular Reactions: Applications to In-Situ Chemical Oxidation of DNAPLs by Permanganate in Fractured Rock

    NASA Astrophysics Data System (ADS)

    Arshadi, Masoud

    Chemical oxidation of dense nonaqueous-phase liquids (DNAPLs) by permanganate has emerged as an effective remediation strategy in fractured rock. Our objectives in this research were to carry out a sequence of experimental, computational and theoretical tasks aimed at improving current understanding of permanganate oxidation in fractured rock systems, and also develop modeling tools that can be used for preliminary design of oxidation schemes at field sites. Our research focused on both free-phase entrapped DNAPL in variable-aperture fractures and dissolved DNAPL in the rock matrix. In the first section of our research, we present high-resolution experimental investigations in transparent analog variable-aperture fractures to improve understanding of chemical oxidation of residual entrapped trichloroethylene (TCE) in fractures. Four experiments were performed with different permanganate concentrations, flow rates, and initial TCE phase geometry. The initial aperture field and evolving entrapped-phase geometry were measured quantitatively. We present results on the time-evolution of fracture-scale TCE consumption and DNAPL removal rates for all the experiments. In the next part of this work, we developed theoretical understanding of the reaction front dynamics in the case of chemical oxidation of aqueous-phase DNAPL within fracture-matrix system, backed up by numerical simulations. We also consider the influence of NOD consumption and contaminant sorption to solid aquifer materials in our models. Based on the results from this task we are able to propose simple strategies for remediation design (e.g. the time needed to degrade DNAPL inside the fracture-matrix system and the permanganate injection pattern) for a given set of conditions. Our numerical simulations of diffusion with bimolecular reaction in the rock matrix demonstrated a transition in the spatially integrated reaction rate - increasing with time initially, and transitioning to a decrease with time. We

  15. Chemiluminescence behaviour of CdTe-potassium permanganate enhanced by sodium hexametaphosphate and sensitized sensing of L-ascorbic acid.

    PubMed

    Chen, Hongqi; Ling, Bo; Yuan, Fei; Zhou, Cailing; Chen, Jingguo; Wang, Lun

    2012-01-01

    A highly sensitive flow-injection chemiluminescence (FIA-CL) method based on the CdTe nanocrystals and potassium permanganate chemiluminescence system was developed for the determination of L-ascorbic acid. It was found that sodium hexametaphosphate (SP), as an enhancer, could increase the chemiluminescence (CL) emission from the redox reaction of CdTe quantum dots with potassium permanganate in near-neutral pH conditions. L-ascorbic acid is suggested as a sensitive enhancer for use in the above energy-transfer excitation process. Under optimal conditions, the calibration graph of emission intensity against logarithmic l-ascorbic acid concentration was linear in the range 1.0 × 10(-9)-5.0 × 10(-6)  mol/L, with a correlation coefficient of 0.9969 and relative standard deviation (RSD) of 2.3% (n = 7) at 5.0 × 10(-7)  mol/L. The method was successfully used to determine L-ascorbic acid in vitamin C tablets. The possible mechanism of the chemiluminescence in the system is also discussed. Copyright © 2012 John Wiley & Sons, Ltd.

  16. Oxidation of MC-LR and -RR with chlorine and potassium permanganate: toxicity of the reaction products.

    PubMed

    Rodríguez, Eva M; Acero, Juan L; Spoof, Lisa; Meriluoto, Jussi

    2008-03-01

    Toxin-producing cyanobacteria are abundant in surface waters used as drinking water resources. Microcystins (MC) produced by certain cyanobacteria present acute and chronic toxicity, and their removal in drinking water treatment processes is of increasing concern. Previous studies have demonstrated that chlorine and potassium permanganate are feasible oxidants for the removal of MCs present in drinking water resources, although the oxidation might lead to toxic oxidation products. In this paper, the toxicity of the oxidation products of MC-LR and -RR has been studied using protein phosphatase 1 inhibition assay (PPIA). The HPLC and ELISA analyses correlated with the PPIA results for both toxins. The samples containing the oxidation products were fractionated by HPLC and the toxicity of the fractions was tested with PPIA. The results revealed that protein phosphatase 1 inhibition emerged only from intact MC, while the oxidation products were non-toxic. Similar results were obtained in experiments performed in natural waters: no reaction products or interactions exhibiting protein phosphatase 1 inhibition were detected.

  17. Physicochemical properties of manganese oxides obtained via the sol-gel method: The reduction of potassium permanganate by polyvinyl alcohol

    NASA Astrophysics Data System (ADS)

    Ivanets, A. I.; Prozorovich, V. G.; Krivoshapkina, E. F.; Kuznetsova, T. F.; Krivoshapkin, P. V.; Katsoshvili, L. L.

    2017-08-01

    Experimental data on the sol-gel synthesis of manganese oxides formed during the reduction of potassium permanganate by polyvinyl alcohol in an aqueous medium are presented. The physicochemical properties of the obtained manganese oxide systems that depend on the conditions of the synthesis are studied by means of DTA, XRD, SEM, and the low temperature adsorption-desorption of nitrogen. It is found that the obtained samples have a mesoporous structure and predominantly consist of double potassium-manganese oxide K2Mn4O8 with a tunnel structure and impurities of oxides such as α-MnO2, MnO, α-Mn2O3, and Mn5O8. It is shown that the proposed method of synthesis allows us to regulate the size and volume of mesopores and, to a lesser extent, the texture of the obtained oxides, which can be considered promising sorbents for the selective extraction of strontium and cesium ions from multicomponent aqueous solutions.

  18. Alkaline permanganate oxidation of kerogens from Cretaceous black shales thermally altered by diabase intrusions and laboratory simulations

    NASA Astrophysics Data System (ADS)

    Ishiwatari, Ryoshi; Morinaga, Shigeo; Simoneit, Bernd R. T.

    1985-08-01

    Potassium permanganate oxidative degradations were conducted for kerogens isolated from Cretaceous black shales (DSDP Leg 41, Site 368), thermally altered during the Miocene by diabase intrusions and from unaltered samples heated under laboratory conditions (250-500°C). Degradation products of less altered kerogens are dominated by normal C4-C15 α,ω-dicarboxylic acids, with lesser amounts of n-C16 and n-C18 monocarboxylic acids, and benzene mono-to-tetracarboxylic acids. On the other hand, thermally altered kerogens show benzene di-to-tetracarboxylic acids as dominant degradation products, with lesser or no amounts (variable depending on the degree of thermal alteration) of α,ω-dicarboxylic acids. Essentially no differences between the oxidative degradation products of naturally- and artificially-altered kerogens are observed. As a result of this study, five indices of aromatization (total aromatic acids/kerogen; apparent aromaticity; benzenetetracarboxylic acids/total aromatic acids; benzene-1,2-dicarboxylic acid/benzenedicarboxylic acids; benzene-1,2,3-tricarboxylic acid/benzenetricarboxylic acids) and two indices of aliphatic character (Total aliphatic acids/kerogen; Aliphaticity) are proposed to characterize the degree of thermal alteration of kerogens. Furthermore, a good correlation is observed between apparent aromaticity estimated by the present KMnO4 oxidation method and that from the 13C NMR method (DENNIS et al., 1982).

  19. Treatment of dye wastewater with permanganate oxidation and in situ formed manganese dioxides adsorption: cation blue as model pollutant.

    PubMed

    Liu, Ruiping; Liu, Huijuan; Zhao, Xu; Qu, Jiuhui; Zhang, Ran

    2010-04-15

    This study investigated the process of potassium permanganate (KMnO(4)) oxidation and in situ formed hydrous manganese dioxides (deltaMnO(2)) (i.e., KMnO(4) oxidation and deltaMnO(2) adsorption) for the treatment of dye wastewater. The effectiveness of decolorization, removing dissolved organic carbon (DOC), and increasing biodegradable oxygen demand (BOD) were compared among these processes of KMnO(4) oxidation, deltaMnO(2) adsorption, and KMnO(4) oxidation and deltaMnO(2) adsorption. DeltaMnO(2) adsorption contributed to the maximum DOC removal of 65.0%, but exhibited limited capabilities of decolorizing and increasing biodegradability. KMnO(4) oxidation alone at pH 0.5 showed satisfactory decrease of UV-vis absorption peaks, and the maximum BOD(5)/DOC value of 1.67 was achieved. Unfortunately, the DOC removal was as low as 27.4%. Additionally, the great amount of acid for pH adjustment and the much too low pH levels limited its application in practice. KMnO(4) oxidation and deltaMnO(2) adsorption at pH 2.0 was the best strategy prior to biological process, in balancing the objectives of decolorization, DOC removal, and BOD increase. The optimum ratio of KMnO(4) dosage to X-GRL concentration (R(KMnO(4)/X-GRL)) was determined to be 2.5, at which KMnO(4) oxidation and deltaMnO(2) adsorption contributed to the maximal DOC removal of 53.4%. Additionally, the optimum pH for X-GRL treatment was observed to be near 3.0.

  20. Permanganate oxidation of α-amino acids: kinetic correlations for the nonautocatalytic and autocatalytic reaction pathways.

    PubMed

    Perez-Benito, Joaquin F

    2011-09-08

    The reactions of permanganate ion with seven α-amino acids in aqueous KH(2)PO(4)/K(2)HPO(4) buffers have been followed spectrophotometrically at two different wavelengths: 526 nm (decay of MnO(4)(-)) and 418 nm (formation of colloidal MnO(2)). All of the reactions studied were autocatalyzed by colloidal MnO(2), with the contribution of the autocatalytic reaction pathway decreasing in the order glycine > l-threonine > l-alanine > l-glutamic acid > l-leucine > l-isoleucine > l-valine. The rate constants corresponding to the nonautocatalytic and autocatalytic pathways were obtained by means of either a differential rate law or an integrated one, the latter requiring the use of an iterative method for its implementation. The activation parameters for the two pathways were determined and analyzed to obtain statistically significant correlations for the series of reactions studied. The activation enthalpy of the nonautocatalytic pathway showed a strong, positive dependence on the standard Gibbs energy for the dissociation of the protonated amino group of the α-amino acid. Linear enthalpy-entropy correlations were found for both pathways, leading to isokinetic temperatures of 370 ± 21 K (nonautocatalytic) and 364 ± 28 K (autocatalytic). Mechanisms in agreement with the experimental data are proposed for the two reaction pathways.

  1. Characteristics of kerogens from Recent marine and lacustrine sediments: GC/MS analysis of alkaline permanganate oxidation products

    NASA Astrophysics Data System (ADS)

    Ishiwatari, Ryoshi; Morinaga, Shigeo; Yamamoto, Shuichi; Machihara, Tsutomu

    Extensive studies have been carried out by many workers on sedimentary kerogens. However little is known of the details of the chemical structure of kerogens and of the relation between immature and mature kerogens on a molecular basis. The present authors have been studying young kerogens (kerogens in young sediments). This study aimed to determine the structural pecularities of young kerogens from marine and lacustrine sediments. Kerogen samples were isolated from marine (Tanner Basin, offshore California) and freshwater lake (Lake Haruna, Japan) sediments. The kerogens belong to Type II or III. These kerogens were oxidized by alkaline permanganate and analyzed for their degradation products by GC/MS. The major degradation products are aliphatic normal α,ω-dicarboxylic acids with carbon numbers of 4-14; aliphatic normal monocarboxylic acids with carbon numbers of 8-26, and benzene mono-, di- and tetracarboxylic acids. A marked difference between kerogens from two environments was observed in the distribution of aliphatic dicarboxylic acids: C 4-C 10 acids are higher for marine kerogens than for lacustrine kerogens. This difference is probably due to the difference in the fatty acid composition of precursory materials (e.g. phytoplankton). These results indicate that the molecular structure of kerogens reflects generally the molecular composition of precursory materials, and consequently the present alkaline KMnO 4 oxidation method is useful for subtyping of kerogens.

  2. Permanganate oxidation of diclofenac: The pH-dependent reaction kinetics and a ring-opening mechanism.

    PubMed

    Cheng, Hanyang; Song, Dean; Liu, Huijuan; Qu, Jiuhui

    2015-10-01

    In this work, the fate of diclofenac (DCF) during permanganate (Mn(VII)) oxidation was investigated at environmentally relevant pH conditions (from 5 to 9). The batch experiments showed that the kinetics of the Mn(VII)/DCF reaction follows a second-order rate law with an apparent rate constant of 1.57±0.02 M(-1) s(-1) at pH 7 and 20 °C. The half-value of DCF was calculated to be 37.5 min, when the concentration of Mn(VII) (0.4 mM) was 20-fold excess of DCF. The pH-dependence of the reaction kinetics was investigated, and the DCF reactivity with Mn(VII) was found to decrease with increasing pH. The second-order rate constants were then quantitatively described by incorporating the species distribution of DCF. A lower reactivity of the anionic DCF (DCF(-)) in comparison with its neutral counterpart (DCF(0)) was most likely attributable to the interaction between the ionized carboxylate group and amine nitrogen position, which can reduce the nucleophilicity of amine nitrogen by inductive and resonance effects. Moreover, a range of degradation products and the corresponding structures were proposed on the basis of the LC-Q-TOF-MS analysis. A detailed ring-opening reaction mechanism was proposed as follows: Mn(VII) acts as an electrophile to attack the amine moiety, leading to the formation of the primary intermediate products 2,6-dichloroaniline and 5-hydroxy-diclofenac, which can be further transformed. The further degradation proceeded through a multistep process including ring-opening, decarboxylation, hydroxylation, and cyclation reactions.

  3. Oxidative degradation of decabromodiphenyl ether (BDE 209) by potassium permanganate: reaction pathways, kinetics, and mechanisms assisted by density functional theory calculations.

    PubMed

    Shi, Jiaqi; Qu, Ruijuan; Feng, Mingbao; Wang, Xinghao; Wang, Liansheng; Yang, Shaogui; Wang, Zunyao

    2015-04-07

    This study found that decabromodiphenyl ether (BDE 209) could be oxidized effectively by potassium permanganate (KMnO4) in sulfuric acid medium. A total of 15 intermediate oxidative products were detected. The reaction pathways were proposed, which primarily included cleavage of the ether bond to form pentabromophenol. Direct oxidation on the benzene ring also played an important role because hydroxylated polybrominated diphenyl ethers (PBDEs) were produced during the oxidation process. The degradation occurred dramatically in the first few minutes and fitted pseudo-first-order kinetics. Increasing the water content decelerated the reaction rate, whereas increasing the temperature facilitated the reaction. In addition, density functional theory (DFT) was employed to determine the frontier molecular orbital (FMO) and frontier electron density (FED) of BDE 209 and the oxidative products. The theoretical calculation results confirmed the proposed reaction pathways.

  4. A Phase Transfer Catalyzed Permanganate Oxidation: Preparation of Vanillin from Isoeugenol Acetate.

    ERIC Educational Resources Information Center

    Lampman, Gary M.; Sharpe, Steven D.

    1983-01-01

    Background information, laboratory procedures, and results are provided for the preparation of vanillin from isoeugenol acetate. Reaction scheme used to prepare the vanillin and a table indicating the different oxidation experiments carried out on isoeugenol or isoeugenol acetate are also provided. (JN)

  5. A Phase Transfer Catalyzed Permanganate Oxidation: Preparation of Vanillin from Isoeugenol Acetate.

    ERIC Educational Resources Information Center

    Lampman, Gary M.; Sharpe, Steven D.

    1983-01-01

    Background information, laboratory procedures, and results are provided for the preparation of vanillin from isoeugenol acetate. Reaction scheme used to prepare the vanillin and a table indicating the different oxidation experiments carried out on isoeugenol or isoeugenol acetate are also provided. (JN)

  6. A Spectrophotometric Study of the Permanganate-Oxalate Reaction: An Analytical Laboratory Experiment

    ERIC Educational Resources Information Center

    Kalbus, Gene E.; Lieu, Van T.; Kalbus, Lee H.

    2004-01-01

    The spectrophotometric method assists in the study of potassium permanganate-oxalate reaction. Basic analytical techniques and rules are implemented in the experiment, which can also include the examination of other compounds oxidized by permanganate.

  7. A Spectrophotometric Study of the Permanganate-Oxalate Reaction: An Analytical Laboratory Experiment

    ERIC Educational Resources Information Center

    Kalbus, Gene E.; Lieu, Van T.; Kalbus, Lee H.

    2004-01-01

    The spectrophotometric method assists in the study of potassium permanganate-oxalate reaction. Basic analytical techniques and rules are implemented in the experiment, which can also include the examination of other compounds oxidized by permanganate.

  8. Determination of moxifloxacin and its oxidation products with kinetic evaluation under potassium permanganate treatment in acidic solution by ultra-performance liquid chromatography/tandem mass spectrometry.

    PubMed

    Hubicka, Urszula; Zmudzki, Paweł; Zajdel, Paweł; Krzek, Jan

    2013-01-01

    A simple, sensitive, and reproducible ultra-performance LC method for the determination of moxifloxacin (MOXI) oxidation stability under permanganate treatment in acidic conditions (pH 3.0-6.0) was developed. Besides the MOXI peak [retention time (RT) = 2.58], four additional products (RT = 0.86, 0.91, 1.42, and 1.89) were observed in all conditions tested. The oxidation process followed second-order reaction kinetics and depended upon solution acidity. The highest reaction rate constant was observed at pH 3.0, and this value decreased as the pH was increased to 6.0. The oxidation products were characterized, and their fragmentation pathways, derived from MS/MS data, were proposed. Two of these products were identified as hydroxyl derivatives of MOXI and two others as their oxidation product analogs with molecular ions of 418.4 and 416.4 m/z, respectively.

  9. Permanganate diffusion and reaction in sedimentary rocks.

    PubMed

    Huang, Qiuyuan; Dong, Hailiang; Towne, Rachael M; Fischer, Timothy B; Schaefer, Charles E

    2014-04-01

    In situ chemical oxidation using permanganate has frequently been used to treat chlorinated solvents in fractured bedrock aquifers. However, in systems where matrix back-diffusion is an important process, the ability of the oxidant to migrate and treat target contaminants within the rock matrix will likely determine the overall effectiveness of this remedial approach. In this study, a series of diffusion experiments were performed to measure the permanganate diffusion and reaction in four different types of sedimentary rocks (dark gray mudstone, light gray mudstone, red sandstone, and tan sandstone). Results showed that, within the experimental time frame (~2 months), oxidant migration into the rock was limited to distances less than 500 μm. The observed diffusivities for permanganate into the rock matrices ranged from 5.3 × 10(-13) to 1.3 × 10(-11) cm(2)/s. These values were reasonably predicted by accounting for both the rock oxidant demand and the effective diffusivity of the rock. Various Mn minerals formed as surface coatings from reduction of permanganate coupled with oxidation of total organic carbon (TOC), and the nature of the formed Mn minerals was dependent upon the rock type. Post-treatment tracer testing showed that these Mn mineral coatings had a negligible impact on diffusion through the rock. Overall, our results showed that the extent of permanganate diffusion and reaction depended on rock properties, including porosity, mineralogy, and organic carbon. These results have important implications for our understanding of long-term organic contaminant remediation in sedimentary rocks using permanganate. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Individual Reactions of Permanganate & Various Reductants

    SciTech Connect

    Gauger, Amber M.; Hallen, Richard T. )

    2000-11-01

    Tank waste on the Hanford Site contains radioactive elements that need to be removed from solution prior to disposal. One effective way to do this is to precipitate the radioactive elements with manganese solids, produced by permanganate oxidation. When added to tank waste, the permanganate, Mn(VII), reacts quickly producing manganese (IV) dioxide precipitate. Because of the speed of reaction it is difficult to tell what exactly is happening. Individual reactions using non-radioactive reductants found in the tanks were done to determine reaction kinetics, what permanganate was reduced to, and what oxidation products were formed. In this project sodium formate, sodium nitrite, glycolic acid, glycine, and sodium oxalate were studied using various concentrations of reductant in alkaline sodium hydroxide solutions. It was determined that formate reacted the quickest, followed by glycine and glycolic acid. Oxalate and nitrite did not appear to react with the permanganate solutions. The formate reactions quickly reduced permanganate, Mn(VII), to manganate, Mn(VI), and then to manganese (IV) dioxide. These reactions oxidized formate to carbonate and water. The glycolic acid was oxidized slower producing oxalate, water, and manganate, which would disproportionate to permanganate and manganese (IV) dioxide solids. The rate at which Mn(VI) disproportionates is usually slower than the rate at which Mn(VII) is reduced to Mn(VI), however in this case the rates were about equal. The glycine reactions formed some ammonia in solution, oxalate, and water. They reacted similar to the glycolic acid reactions, producing manganese dioxide precipitate before the solution turned totally green from Mn(VI). The formate reactions consumed one mole of hydroxide for every 3 moles of formate, while the glycolic acid and glycine reactions consumed 7 moles of hydroxide for every 3 moles of reductant. These reactions should help to determine the majority of products found in mixtures of solutions.

  11. DNAPL remediation with in situ chemical oxidation using potassium permanganate - II. Increasing removal efficiency by dissolving Mn oxide precipitates

    NASA Astrophysics Data System (ADS)

    Li, X. David; Schwartz, Franklin W.

    2004-02-01

    In situ chemical oxidation (ISCO) schemes using MnO 4- have been effective in destroying chlorinated organic solvents dissolved in ground water. Laboratory experiments and field pilot tests reveal that the precipitation of Mn oxide, one of the reaction products, causes a reduction of permeability, which can lead to flow bypassing and inefficiency of the scheme. Without a solution to this problem of plugging, it is difficult to remove DNAPL from the subsurface completely. In a companion paper, we showed with batch experiments that Mn oxide can be dissolved rapidly with certain organic acids. This study utilizes 2-D flow-tank experiments to examine the possibility of nearly complete DNAPL removal by ISCO with MnO 4-, when organic acids are used to remove Mn oxide. The experiments were conducted in a small 2-D glass flow tank containing a lenticular silica-sand medium. Blue-dyed trichloroethylene (TCE) provided residual, the perched and pooled DNAPL. KMnO 4 at 200 mg/l was flushed through the DNAPL horizontally. Once plugging reduced permeability and prevented further delivery of the oxidant, citric or oxalic acids were pumped into the flow tank to dissolve the Mn oxide precipitates. Organic ligands removed the Mn oxide precipitates relatively quickly, and permitted another cycle of MnO 4- flooding. Cycles of MnO 4-/acid flooding continued until all of the visible DNAPL was removed. The experiments were monitored with chemical analysis and visualization. A mass-balance calculation indicated that by the end of the experiments, all the DNAPL was removed. The results show also how heterogeneity adds complexity to initial redistribution of DNAPL, and to the efficiency of the chemical flooding.

  12. Coupling Surfactants with Permanganate for PCE DNAPL Removal: Coinjection or Sequential Application as Delivery Methods

    NASA Astrophysics Data System (ADS)

    Dugan, P. J.; Siegrist, R. L.; Crimi, M. L.

    2008-12-01

    Batch experiments and two-dimensional (2-D) flow-through cell experiments were conducted to investigate coupling surfactant-enhanced aquifer remediation (SEAR) with in situ chemical oxidation (ISCO) of tetrachloroethene (PCE) dense nonaqueous phase liquid (DNAPL) for PCE mass destruction. Previous batch screening tests were performed on surfactants and cosolvents in the presence of the oxidant potassium permanganate, to assess compatibility for coupling with permanganate. The anionic surfactants sodium dioctyl sulfosuccinate (Aerosol OT), and sodium hexadecyl diphenyl oxide disulfonate (Dowfax 8390) were compatible and selected for use. Two delivery methods were investigated: (1) coinjection of 0.66 pore volumes (PVs) of 1.0-wt% Aerosol-OT, 0.5-wt% Dowfax 8390, 0.35-wt% CaBr2, and 0.75-wt% NaBr, (for enhanced PCE solubilization) with 0.5-wt% permanganate(for DNAPL mass destruction), and (2) sequential application of 0.66 PVs of the same surfactant solution followed by 0.66 PVs of 0.5-wt% permanganate flush. The 2-D cell packing configuration consisted of a fine-grained silica sand matrix with an embedded medium- grained sand lens, which allowed for the development of a high saturation PCE DNAPL source zone (~9-11% v/v) within the lens of each cell. For both experiments the flushing solutions were delivered at a linear velocity of 52 cm/day. Water quality samples were collected from eight point sampling ports, as well as the cell effluent. Samples were analyzed for PCE, chloride, and permanganate. At the conclusion of the experiments, the mass of PCE removed was quantified by destructively analyzing the cell. Results indicate complete mass removal using sequential application as a delivery method. In the coinjection experiment, cores extracted at the conclusion revealed that 99.8% of PCE DNAPL mass was removed. However, it was not possible to close a mass balance between the initial PCE added and the PCE removed. It is hypothesized this result was due to incomplete

  13. Separation and characterization of ciprofloxacin, difloxacin, lomefloxacin, norfloxacin, and ofloxacin oxidation products under potassium permanganate treatment in acidic medium by UPLC-MS/MS.

    PubMed

    Hubicka, Urszula; Zmudzki, Paweł; Zuromska-Witek, Barbara; Zajdel, Paweł; Pawłowski, Maciej; Krzek, Jan

    2013-05-15

    A simple, sensitive and reproducible ultra-performance liquid chromatography method for determination of ciprofloxacin, difloxacin, lomefloxacin, norfloxacin and ofloxacin oxidation stability under permanganate treatment in acidic conditions at pH from 3.0 to 6.0, was developed. Chromatographic separations were carried out using the Acquity UPLC BEH C18 column; (2.1×100 mm, 1.7 μm particle size). The column was maintained at 40°C, and eluted under isocratic conditions using 83% of eluent A and 17% of eluent B over 6.5 min, at a flow rate of 0.3 mL min(-1). Eluent A: water/formic acid (0.1 v/v%); eluent B: acetonitrile/formic acid (0.1 v/v%). An oxidation process followed kinetic of the second order reaction and depended upon solution acidity. Oxidation of fluoroquinolones proceeded at piperazine moiety yielding respective hydroxy and oxo analogs, and remaining the quinolone fragment intact. Structures of products formed were assigned on a basis of UPLC/MS/MS fragmentation pathways. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Lowering temperature to increase chemical oxidation efficiency: the effect of temperature on permanganate oxidation rates of five types of well defined organic matter, two natural soils, and three pure phase products.

    PubMed

    de Weert, J P A; Keijzer, T J S; van Gaans, P F M

    2014-12-01

    In situ chemical oxidation (ISCO) is a soil remediation technique to remove organic pollutants from soil and groundwater with oxidants, like KMnO4. However, also natural organic compounds in soils are being oxidized, which makes the technique less efficient. Laboratory experiments were performed to investigate the influence of temperature on this efficiency, through its effect on the relative oxidation rates - by permanganate - of natural organic compounds and organic pollutants at 16 and 15°C. Specific types of organic matter used were cellulose, oak wood, anthracite, reed - and forest peat, in addition to two natural soils. Dense Non-Aqueous Phase Liquid-tetrachloroethene (DNAPL-PCE), DNAPL trichloroethene (DNAPL-TCE) and a mixture of DNAPL-PCE, -TCE and -hexachlorobutadiene were tested as pollutants. Compared to 16°C, oxidation was slower at 5°C for the specific types of organic matter and the natural soils, with exception of anthracite, which was unreactive. The oxidation rate of DNAPL TCE was lower at 5°C too. However, at this temperature oxidation was fast, implying that no competitive loss to natural organic compounds will be expected in field applications by lowering temperature. Oxidation of DNAPL-PCE and PCE in the mixture proceeded at equal rates at both temperatures, due to the dissolution rate as limiting factor. These results show that applying permanganate ISCO to DNAPL contamination at lower temperatures will limit the oxidation of natural organic matter, without substantially affecting the oxidation rate of the contaminant. This will make such remediation more effective and sustainable in view of protecting natural soil quality.

  15. Headspace single-drop microextraction and fibre optics-based cuvetteless micro-spectrophotometry for the determination of chloride involving oxidation with permanganate.

    PubMed

    Pillai, Aradhana K K V; Jain, Archana; Verma, Krishna K

    2010-03-15

    Headspace single-drop microextraction has been investigated for the determination of chloride in conjunction with fibre optic-based cuvetteless micro-spectrophotometry which accommodates sample volume of 1 microL placed between the two ends of optical fibres. Method has been evolved for the determination of 0.025-4 mg L(-1) of chloride involving its oxidation with permanganate in sulphuric acid medium, and reaction of chlorine with 2 microL drop of starch-iodide reagent suspended at the tip of microsyringe needle in the headspace of the reaction mixture. The limit of detection was found to be 2.8 microg L(-1) of chloride which was better than obtained by existing methods. The method was highly selective and a number of ions which interfered severely in other methods did not affect the results. The method has been used to analyze water samples, inorganic compounds and cement when the overall recovery of chloride was 94.9% with a relative standard deviation of 3.9%.

  16. Structural Study of the Incorporation of Heavy Metals into Solid Phase Formed During the Oxidation of EDTA by Permanganate at High pH

    SciTech Connect

    Korshin,G.; Chang, H.; Frenkel, A.; Ferguson, J.

    2007-01-01

    Properties of solid phases formed during the oxidation of EDTA by permanganate in a high-pH, high-ionic strength solution, and the retention of Cu{sup 2+}, Ni{sup 2+}, and Zn{sup 2+} by them were examined. Morphologically, the solids were agglomerates of particles with sizes <100 nm. X-ray absorption spectroscopy (XAS) analysis indicated that these particles were birnessite. Its precipitation was accompanied by the removal of Zn2+ and Cu2+ released as a result of the breakdown of their complexes with EDTA. However, Ni{sup 2+} was not removed from the supernatant. Cu{sup 2+} was strongly bound by birnessite and exhibited little mobility in the pH range from 3 to 14. Zn{sup 2+} was more mobile, especially at pH > 12. XAS showed that Cu{sup 2+} binding sites were located within MnO{sub 6} octahedra-comprised sheets that constitute birnessite while Zn{sup 2+} was positioned between them.

  17. Enhanced removal of organics by permanganate preoxidation using tannic acid as a model compound--role of in situ formed manganese dioxide.

    PubMed

    Zhang, Lizhu; Ma, Jun; Li, Xin; Wang, Shutao

    2009-01-01

    The effect of permanganate preoxidation on organic matter removal during the coagulation with aluminum chloride was investigated using tannic acid as a model compound. Results showed that a small amount of KMnO4 (0.75 mg/L) increased the removal efficiency of tannic acid up to 20%, as compared to the process of coagulation by aluminum chloride alone. The key factor enhancing the removal efficiency of tannic acid in preoxidation process was the in situ formation of a reductant manganese dioxide. The complexation model was used to describe the reaction between MnO2 and tannic acid. Under weak pH condition, tannic acid was difficult to be adsorbed by MnO2 due to the static electrical repulsive forces. The presence of Ca2+ served as a bridge to hold the negative charged MnO2 and tannic acid together, which could be a crucial factor influencing tannic acid adsorption by in-situ manganese dioxide.

  18. Exploring the potential of the permanganate oxidation method as a tool to monitor soil quality in agricultural upland systems of Southeast Asia

    NASA Astrophysics Data System (ADS)

    Hepp, Catherine M.; Bruun, Thilde Bech; de Neergaard, Andreas

    2014-05-01

    The transition to more intensified upland systems is having an impact on the soil quality, defined as the ability of a soil to both provide and maintain essential services to an ecosystem. As many tropical upland soils are inherently low in quality, it is essential that impacts be monitored. Soil quality is assessed by using a combination of parameters that serve as indicators and cover the soil chemical, biological and physical properties. An ideal indicator should be sensitive to changes in the environment and management practices and should be widely accessible, meaning low resource requirement (i.e. time and equipment). Total organic carbon (TOC) content is a commonly used indicator of soil quality as it is linked to many soil functions and processes; however analysis is costly and requires access to advanced instrumental facilities, rendering it unsuited for many developing countries. An alternative indicator is the soil fraction dominated by easily decomposable carbon; this may be measured by treating soil samples with 0.2M potassium permanganate (KMnO4), an oxidizing agent which is thought to mimic the enzymes released by the soil microbial community. The advantage of this method is that it is accessible: it is fast, requires little resource input and is field appropriate. There is no consensus however as to which soil carbon fraction the method targets. Furthermore Skjemstad et al. (2006) has indicated that KMnO4 may oxidise charcoal, a component of the non-labile carbon pool; this has implications for the suitability of the method when used for soils of shifting cultivation systems. The purpose of this study was to investigate the potential of permanganate oxidizable carbon (Pox C) as a reliable indicator of soil quality in agricultural upland systems in Northern Lao PDR. Focus was placed on the relations between Pox C and other soil quality parameters (bulk density, pH, CEC, TOC, total N, exchangeable K, plant available P) and upland rice yields. The

  19. Enhanced mercury oxidation

    SciTech Connect

    Gretta, W.J.; Wu, S.; Kikkawa, H.

    2009-06-15

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

  20. Sustained-Release Permanganate: Passive Reactive Barriers for Green and Sustainable Remediation

    NASA Astrophysics Data System (ADS)

    Dugan, P. J.

    2011-12-01

    Reactive materials in permeable reactive barriers (PRBs) have proven very useful for transforming or destroying organic waste in situ. Once emplaced they typically do not require a continued supply of electrical power and have the added benefit of creating a reactive zone for the destruction of contaminants in place. Controlled-release techniques have been utilized extensively in diverse fields such as pharmaceutical and agrochemical technologies. However, controlled- and sustained release of an oxidant during in situ chemical oxidation (ISCO) is an emerging concept that is extremely relevant to the field of environmental remediation, yet to-date has received little attention. ISCO using the oxidants permanganate, persulfate, and catalyzed hydrogen peroxide has shown great promise for remediation of many recalcitrant organic contaminants of concern (COC). Because the oxidant also reacts with natural organic matter, inorganic soil constituents, and other reduced compounds, the presence of a protective barrier that controls oxidant release may enhance the efficiency of ISCO and allow for long-term low-cost treatment of chlorinated solvents. To this end, sustained-release permanganate (SRP) was developed. Paraffin wax was used as the environmentally benign and biodegradable matrix material for encapsulating the solid potassium permanganate (KMnO4) particles. The paraffin matrix protects the solid KMnO4 particles from fast dissolution and potentially undesirable nonproductive reactions. The SRP material contains between 60%-80% permanganate and can be formed as candles for direct push applications in reactive barriers, or chipped material for hydro-fracturing into low permeability media. One-dimensional (1-D) SRP column experiments were conducted to evaluate permanganate release behavior using deionized (DI) water as the influent or COC removal efficiency using dissolved trichloroethene (TCE) as the influent. The influent dissolved TCE concentrations were 1 mg/L and

  1. Beware of the Permanganate Volcano.

    ERIC Educational Resources Information Center

    Snyder, Ellie

    1980-01-01

    Discusses hazards associated with the permanganate demonstration of volcanic eruptions. Alternate demonstrations are described, including the ammonium dichromate reaction, lava flow demonstration with baking soda and vinegar, and punk to illustrate air pollution from volcanic ash and cinders. (CS)

  2. Beware of the Permanganate Volcano.

    ERIC Educational Resources Information Center

    Snyder, Ellie

    1980-01-01

    Discusses hazards associated with the permanganate demonstration of volcanic eruptions. Alternate demonstrations are described, including the ammonium dichromate reaction, lava flow demonstration with baking soda and vinegar, and punk to illustrate air pollution from volcanic ash and cinders. (CS)

  3. 75 FR 51112 - Potassium Permanganate From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-18

    ... COMMISSION Potassium Permanganate From China AGENCY: United States International Trade Commission. ACTION: Scheduling of an expedited five-year review concerning the antidumping duty order on potassium permanganate... whether revocation of the antidumping duty order on potassium permanganate from China would be likely to...

  4. 75 FR 23298 - Potassium Permanganate From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-03

    ... COMMISSION Potassium Permanganate From China AGENCY: United States International Trade Commission. ACTION: Institution of a five-year review concerning the antidumping duty order on potassium permanganate from China... antidumping duty order on potassium permanganate from China would be likely to lead to continuation or...

  5. Nitric oxide enhancement strategies.

    PubMed

    Bryan, Nathan S

    2015-08-01

    It is becoming increasingly clear that many diseases are characterized or associated with perturbations in nitric oxide (NO) production/signaling. Therapeutics or strategies designed to restore normal NO homeostasis will likely have broad application and utility. This highly complex and multistep pathway for NO production and subsequent target activation provides many steps in the endogenous pathway that may be useful targets for drug development for cardiovascular disease, antimicrobial, cancer, wound healing, etc. This article will summarize known strategies that are currently available or in development for enhancing NO production or availability in the human body. Each strategy will be discussed including exogenous sources of NO, use of precursors to promote NO production and downstream pathways affected by NO production with advantages and disadvantages highlighted for each. Development of NO-based therapeutics is and will continue to be a major focus of biotech, academia as well as pharmaceutical companies. Application of safe and effective strategies will certainly transform health and disease.

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

    SciTech Connect

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

    1993-08-03

    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.

  7. Nitric oxide enhancement strategies

    PubMed Central

    Bryan, Nathan S

    2015-01-01

    It is becoming increasingly clear that many diseases are characterized or associated with perturbations in nitric oxide (NO) production/signaling. Therapeutics or strategies designed to restore normal NO homeostasis will likely have broad application and utility. This highly complex and multistep pathway for NO production and subsequent target activation provides many steps in the endogenous pathway that may be useful targets for drug development for cardiovascular disease, antimicrobial, cancer, wound healing, etc. This article will summarize known strategies that are currently available or in development for enhancing NO production or availability in the human body. Each strategy will be discussed including exogenous sources of NO, use of precursors to promote NO production and downstream pathways affected by NO production with advantages and disadvantages highlighted for each. Development of NO-based therapeutics is and will continue to be a major focus of biotech, academia as well as pharmaceutical companies. Application of safe and effective strategies will certainly transform health and disease. PMID:28031863

  8. Binary Mixtures of Permanganate and Chlorinated Volatile Organic Compounds in Groundwater Samples: Sample Preservation and Analysis

    EPA Science Inventory

    Ground water samples collected at sites where in-situ chemical oxidation (ISCO) has been deployed may contain binary mixtures of ground water contaminants and permanganate (MnO4-), an oxidant injected into the subsurface to destroy the contaminant. Commingling of the oxidant and ...

  9. Binary Mixtures of Permanganate and Chlorinated Volatile Organic Compounds in Groundwater Samples: Sample Preservation and Analysis

    EPA Science Inventory

    Ground water samples collected at sites where in-situ chemical oxidation (ISCO) has been deployed may contain binary mixtures of ground water contaminants and permanganate (MnO4-), an oxidant injected into the subsurface to destroy the contaminant. Commingling of the oxidant and ...

  10. Cyanobacterial Treatment Options: Permanganate and ...

    EPA Pesticide Factsheets

    This presentation will begin with a brief overview of drinking water treatment options for cyanobacteria and their toxins. The treatment discussion will focus on the impacts of permanganate addition to suspensions of toxin-producing Microcystis aeruginosa, followed by powdered activated carbon (PAC) addition. Results will be presented that show changes in toxin concentrations, chlorophyll-a concentrations and cell membrane integrity. The EPA Small Systems Webinar Presentations allow the dissemination of the latest Agency guidance and research to a large geographically dispersed audience while minimizing taxpayer expense

  11. Permanganate Treatment of DNAPLs in Reactive Barriers and Source Zone Flooding Schemes

    SciTech Connect

    Dr. Franklin Schwartz; Dr. Hubao Zhang

    2003-12-23

    Permanganate is a simple and common chemical, which has proven useful in oxidizing common chlorinated solvents. Due to the nature of oxidation, the byproducts and products are much less harmful than those from reduction-type remedial schemes, and the degradation process is rapid. The main goal of this project is to understand oxidative destruction of chlorinated solvents using potassium permanganate. The study has provided a theoretical basis for evaluating the feasibility of in-situ applications, to couple kinetic reaction with transport models, and to develop an appropriate field test for further assessing the approach.

  12. Using slow-release permanganate candles to remediate PAH-contaminated water.

    PubMed

    Rauscher, Lindy; Sakulthaew, Chainarong; Comfort, Steve

    2012-11-30

    Surface waters impacted by urban runoff in metropolitan areas are becoming increasingly contaminated with polycyclic aromatic hydrocarbons (PAHs). Slow-release oxidant candles (paraffin-KMnO(4)) are a relatively new technology being used to treat contaminated groundwater and could potentially be used to treat urban runoff. Given that these candles only release permanganate when submerged, the ephemeral nature of runoff events would influence when the permanganate is released for treating PAHs. Our objective was to determine if slow-release permanganate candles could be used to degrade and mineralize PAHs. Batch experiments quantified PAH degradation rates in the presence of the oxidant candles. Results showed most of the 16 PAHs tested were degraded within 2-4 h. Using (14)C-labled phenanthrene and benzo(a)pyrene, we demonstrated that the wax matrix of the candle initially adsorbs the PAH, but then releases the PAH back into solution as transformed, more water soluble products. While permanganate was unable to mineralize the PAHs (i.e., convert to CO(2)), we found that the permanganate-treated PAHs were much more biodegradable in soil microcosms. To test the concept of using candles to treat PAHs in multiple runoff events, we used a flow-through system where urban runoff water was pumped over a miniature candle in repetitive wet-dry, 24-h cycles. Results showed that the candle was robust in removing PAHs by repeatedly releasing permanganate and degrading the PAHs. These results provide proof-of-concept that permanganate candles could potentially provide a low-cost, low-maintenance approach to remediating PAH-contaminated water. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Permanganate-assisted removal of PCR inhibitors during the DNA Chelex extraction from stained denim samples.

    PubMed

    Pîrlea, Sorina; Puiu, Mihaela; Răducan, Adina; Oancea, Dumitru

    2017-03-01

    In this study, it was demonstrated that the DNA Chelex extraction combined with the permanganate assisted-oxidation is highly efficient in removing the PCR inhibitors often found in clothing materials, such as phthalocyanine. The extraction assays were conducted in saliva, blood and epithelial cells samples mixed with three oxidation-resistant dye copper(II) α-phthalocyanine, copper(II) β-phthalocyanine and tetrasulfonated copper(II) β-phthalocyanine. After DNA amplification, all samples were able to provide full DNA profiles. The permanganate/Chelex system was tested further on denim-stained samples and displayed the same ability to remove the PCR inhibitors from the commercial textile materials.

  14. Enhanced utilization of oxidants for in situ chemical oxidation of chlorinated and aromatic hydrocarbons

    NASA Astrophysics Data System (ADS)

    Kang, Namgoo

    Potentially viable strategies were sought for enhanced utilization of potassium permanganate (KMnO4) and Fenton's reagent during in situ chemical oxidation (ISCO). An innovative concept of controlled release of oxidant was introduced and organic-coated, completely or partially microencapsulated KMnO4 (MEPP) particles (874 +/- 377 mum) were created to serve a material that can be specifically targeted to a contaminant source zone. Paraffin wax was employed as the coating material because it is biodegradable, inert to KMnO4, insoluble in water and yet soluble in hydrophobic contaminants such as perchloroethylene (PCE). KMnO4 was released very slowly into water, but the oxidant was rapidly released into PCE. The estimated times for 90% release of the oxidant were 1.6 months, 19.3 years, and 472 years for paraffin wax to KMnO4 mass ratios of 1:1, 2:1 and 5:1, respectively. The MEPP particles preferentially accumulated at the PCE-water interface, and the KMnO4 was rapidly released into PCE (<3 min) as the paraffin wax completely dissolved. These findings suggest that enhanced contact between the target contaminant and the locally high concentrations of KMnO 4 could be achieved at the interfacial region between PCE and water. Fenton's oxidative destruction was investigated for aromatic hydrocarbons (benzene, toluene, ethylbenzene, and o-xylene; BTEX) present as dissolved and adsorbed phases, and chlorinated hydrocarbon (PCE) present mostly as dense non-aqueous phase liquid (DNAPL) (>93% of total PCE mass) in batch reactors (soil: solution = 1 g/L). An enhanced mass removal was observed by combining 300 mM H2O2, 2 mM Fe(III) and 2 mM N-(2-hydroxyethyl)iminodiacetic acid (HEIDA) at near-neutral pH. The PCE degradation was maximal at 600 mM H2O2, 5 mM Fe(III) and 5 mM HEIDA at pH 3. The observed BTEX mass removal rate constants (3.6--7.8 x 10-4 s-1) were compared to the estimated ones (4.1--10.1 x 10-3 s-1) using a semi-quantitative kinetic model. The model sensitivity

  15. β-CD assisted dissolution of quaternary ammonium permanganates in aqueous medium.

    PubMed

    Bank, Suraj Prakash; Guru, Partha Sarathi; Dash, Sukalyan

    2014-10-13

    The non-polar internal cavity of β-cyclodextrin (β-CD) has been exploited for the entrapment of the hydrophobic tails of two water insoluble quaternary ammonium permanganates (QAPs): cetyltrimethylammonium permanganate (CTAP) and tetrabutylammonium permanganate (TBAP), for solubilization in aqueous medium. The solubilization and organizational behavior of the QAPs in aqueous β-CD solution have been determined from the comparison of their rates of self-oxidation in presence and in absence of β-CD. Effect of QAP concentration on their observed rate constants (k(obs)) at a fixed β-CD concentration, phase solubility analysis in varying β-CD concentration, impact of quaternary ammonium bromides (QABs) on the kobs values of CTAP and TBAP at fixed QAP and β-CD concentrations, and the temperature effect have been reported. A scheme to explain the solvation of QAPs in aqueous β-CD has been proposed based on dynamic light scattering (DLS) analysis of the samples.

  16. Tested Demonstrations. The Stepwise Reduction of Permanganate in Alkaline Conditions: A Lecture Demonstration.

    ERIC Educational Resources Information Center

    Ruoff, Peter; Riley, Megan

    1987-01-01

    Describes a chemistry experiment where an alkaline ice-cold permanganate solution is reduced by adding dropwise a cold diluted hydrogen peroxide solution. Outlines the course of the reduction through the various oxidation states of manganese with their characteristic colors. (TW)

  17. Tested Demonstrations. The Stepwise Reduction of Permanganate in Alkaline Conditions: A Lecture Demonstration.

    ERIC Educational Resources Information Center

    Ruoff, Peter; Riley, Megan

    1987-01-01

    Describes a chemistry experiment where an alkaline ice-cold permanganate solution is reduced by adding dropwise a cold diluted hydrogen peroxide solution. Outlines the course of the reduction through the various oxidation states of manganese with their characteristic colors. (TW)

  18. 75 FR 63856 - Potassium Permanganate From China Determination

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-18

    ... COMMISSION Potassium Permanganate From China Determination On the basis of the record \\1\\ developed in the... antidumping duty order on potassium permanganate from China would be likely to lead to continuation or... Potassium Permanganate from China: Investigation No. 731-TA- 125 (Third Review). Issued: October 1, 2010. By...

  19. Permanganate treatment of DNAPLs in reactive barriers and source zone flooding schemes. 1997 annual progress report

    SciTech Connect

    Schwartz, F.W.

    1997-01-01

    'The goals of this study are (1) to elucidate the basic mechanisms by which potassium permanganate oxidizes common chlorinated solvents, various constituents in aqueous solution, and porous-medium solids, and (2) to assess the potential for chemical oxidation by potassium permanganate to serve as a remedial scheme involving either source zone flooding or reactive barriers. The research plan involves a combined experimental/modeling study that builds on the extensive previous work in the area of reactive barrier systems, and modeling of reactive contaminant transport. The experimental studies are being undertaken at The Ohio State University by Dr. Schwartz and his co-workers. The modeling work is being conducted in Albuquerque, NM by Dr. Zhang of Intera, Inc. The workplan for this study is designed around the following four objectives (1) to describe through batch experiments the kinetics and mechanisms by which potassium permanganate oxidizes dissolved tetrachloroethene (PCE), trichloroethene (TCE), and dichloroethene (DCE), (2) to examine using column studies the nature and kinetics of reactions between potassium permanganate, residual DNAPLs (PCE, TCE, and DCE) and porous medium solids, (3) to represent the process understanding in flow and transport models that demonstrate the potential applicability of the approach, and (4) to apply the resulting computer code in the development of appropriate field tests for assessing the approach.'

  20. Improving the treatment of non-aqueous phase TCE in low permeability zones with permanganate.

    PubMed

    Chokejaroenrat, Chanat; Comfort, Steve; Sakulthaew, Chainarong; Dvorak, Bruce

    2014-03-15

    Treating dense non-aqueous phase liquids (DNAPLs) embedded in low permeability zones (LPZs) is a particularly challenging issue for injection-based remedial treatments. Our objective was to improve the sweeping efficiency of permanganate (MnO4(-)) into LPZs to treat high concentrations of TCE. This was accomplished by conducting transport experiments that quantified the penetration of various permanganate flooding solutions into a LPZ that was spiked with non-aqueous phase (14)C-TCE. The treatments we evaluated included permanganate paired with: (i) a shear-thinning polymer (xanthan); (ii) stabilization aids that minimized MnO2 rind formation and (iii) a phase-transfer catalyst. In addition, we quantified the ability of these flooding solutions to improve TCE destruction under batch conditions by developing miniature LPZ cylinders that were spiked with (14)C-TCE. Transport experiments showed that MnO4(-) alone was inefficient in penetrating the LPZ and reacting with non-aqueous phase TCE, due to a distinct and large MnO2 rind that inhibited the TCE from further oxidant contact. By including xanthan with MnO4(-), the sweeping efficiency increased (90%) but rind formation was still evident. By including the stabilization aid, sodium hexametaphosphate (SHMP) with xanthan, permanganate penetrated 100% of the LPZ, no rind was observed, and the percentage of TCE oxidized increased. Batch experiments using LPZ cylinders allowed longer contact times between the flooding solutions and the DNAPL and results showed that SHMP+MnO4(-) improved TCE destruction by ∼16% over MnO4(-) alone (56.5% vs. 40.1%). These results support combining permanganate with SHMP or SHMP and xanthan as a means of treating high concentrations of TCE in low permeable zones.

  1. Use of potassium permanganate for iron and manganese removal from acid mine drainage

    SciTech Connect

    Boll, J.E.; Deshinsky, G.

    1985-12-09

    Surface and deep shaft coal mining operations find it difficult to meet Environmental Protection Agency (EPA) standards concerning acid, iron and manganese in drainage waters. Correcting the acid and iron problem is relatively simple, but effectively controlling manganese is more difficult. The best way to remove manganese is by chemical oxidation. A common treatment method is pH adjustment with lime or soda ash. This practice neutralizes the acid and removes most of the iron by forming an insoluble precipitate. The amount of lime or soda ash needed to remove manganese raises the pH beyond the acceptable range of 6-9. Potassium permanganate (KMnO/sub 4/) can be used to oxidize the dissolved manganese to an insoluble manganese precipitate. It can also oxidize any residual iron. The adjusted pH reduces unnecessary consumption of permanganate needed to oxidize manganese and meets EPA standards. It reacts on contact producing an insoluble manganese dioxide (MnO/sub 2/). The MnO/sub 2/ supplements the oxidation with a settling effect. Permanganate can be applied at all pHs, with faster results at neutral or slightly alkaline levels. Its use for iron and manganese removal is very attractive because the reactions are complete, rapid, and require only a minimal amount of chemicals. Laboratory evaluation and field case histories will be discussed in the paper. 3 figures.

  2. Photo-enhanced oxidation of nickel

    NASA Astrophysics Data System (ADS)

    Mesarwi, A.; Ignatiev, A.; Liu, J. S.

    1988-02-01

    The oxidation in air of polycrystalline nickel samples at bulk temperatures of 400°C and 500°C under both infrared oven heating and high flux visible/near u.v. irradiation (⩾ 1 MW/m 2) is examined. The oxide thickness is found to be over 400% greater under photo-irradiation at 3.5 MW/m 2 and 400°C bulk temperature than under infrared irradiation at an equivalent temperature. Also, the oxide thickness is found to increase linearly with increasing flux. This photo-enhanced oxidation is believed to be mainly due to electronic excitation of the surface adsorbed molecular oxygen species with subsequent enhanced dissociation. This leads to increased oxidation kinetics and ultimately to the observed increase in oxide thickness.

  3. Comparison of permanganate preoxidation and preozonation on algae containing water: cell integrity, characteristics, and chlorinated disinfection byproduct formation.

    PubMed

    Xie, Pengchao; Ma, Jun; Fang, Jingyun; Guan, Yinghong; Yue, Siyang; Li, Xuchun; Chen, Liwei

    2013-12-17

    Aqueous suspensions of Microcystis aeruginosa were preoxidized with either ozone or permanganate and then subjected to chlorination under conditions simulating drinking water purification. The impacts of the two oxidants on the algal cells and on the subsequent production of dissolved organic matter and disinfection byproducts were investigated. Preozonation dramatically increased disinfection byproduct formation during chlorination, especially the formation of haloaldehydes, haloacetonitriles, and halonitromethanes. Preoxidation with permanganate had much less effect on disinfection byproduct formation. Preozonation destroyed algal cell walls and cell membranes to release intracellular organic matter (IOM), and less than 2.0% integrated cells were left after preozonation with the dosage as low as 0.4 mg/L. Preoxidation with permanganate mainly released organic matter adsorbed on the cells' surface without causing any damage to the cells' integrity, so the increase in byproduct formation was much less. More organic nitrogen and lower molecular weight precursors were produced in a dissolved phase after preozonation than permanganate preoxidation, which contributes to the significant increase of disinfection byproducts after preozonation. The results suggest that permanganate is a better choice than ozone for controlling algae derived pollutants and disinfection byproducts.

  4. N-nitrosodimethylamine (NDMA) as a product of potassium permanganate reaction with aqueous solutions of dimethylamine (DMA).

    PubMed

    Andrzejewski, Przemysław; Nawrocki, Jacek

    2009-03-01

    The reactivity of permanganate with dimethylamine, as possible path of NDMA formation, has been investigated. The results have shown that potassium permanganate reaction with aqueous solutions of dimethylamine (DMA) leads to the formation of N-nitrosodimethylamine (NDMA). The contact time, the molar ratio of permanganate and DMA, pH and presence of nitrite are the key factors influencing the efficiency of NDMA formation. Significant conversion rates of DMA to NDMA were observed only for the high doses of permanganate, which were many times higher than those typically used in water treatment. This reaction however is of importance for water treatment technology, since it shows the possibility of NDMA formation as a result of oxidation of DMA. It is likely that nitrosation is the main path of the reaction. An important role of MnO2 suspension, formed as a result of permanganate reduction in NDMA formation is emphasized. Significant influence of MnO2 suspension on NDMA formation should draw our attention to the potential impact of MnO2 activated filtration beds on NDMA formation.

  5. Reactivity of β-blockers/agonists with aqueous permanganate. Kinetics and transformation products of salbutamol.

    PubMed

    Rodríguez-Álvarez, Tania; Rodil, Rosario; Quintana, José Benito; Cela, Rafael

    2015-08-01

    The possible oxidation of two β-blockers, atenolol and propranolol, and one β-agonist, salbutamol, with aqueous potassium permanganate (KMnO4) was investigated by liquid chromatography-quadrupole-time-of-flight-mass spectrometry (LC-QTOF-MS). Under strong oxidation conditions (2 mg L(-1) KMnO4, 24 h), only salbutamol did significantly react. In this way, the oxidation kinetics of salbutamol was further investigated at different concentrations of KMnO4, chloride, phosphate and sample pH by means of a full factorial experimental design. Depending on these factors, half-lives were in the range 1-144 min for drug and it was observed that KMnO4 concentration was the most significant factor, resulting in increased reaction rate as it is increased. Moreover, the reaction of salbutamol is also enhanced at basic pH and to a minor extent by the presence of phosphates, being both factors more relevant at low KMnO4 concentrations. The use of an accurate-mass LC-QTOF-MS system permitted the identification of a total of seven transformation products (TPs). The transformation path of the drug begins by the attack of KMnO4 on two double bonds of the aromatic ring of salbutamol via 3 + 2 and 2 + 2 addition reactions, which resulted in the ring opening and that continues with oxidative reactions to finally produce smaller size TPs, ending with tert-butyl-formamide, as the smallest TP identified. Reaction in real samples showed a slower and partial oxidation of the pharmaceutical, due to other competing water organic constituents, but still exceeding 60%. Moreover, the software predicted toxicity of TPs indicates that they are expected not to be more toxic than salbutamol, in contrast to the results obtained for the predicted toxicity of chlorination TPs, excepting predicted developmental toxicity.

  6. Activation of Manganese Oxidants with Bisulfite for Enhanced Oxidation of Organic Contaminants: The Involvement of Mn(III).

    PubMed

    Sun, Bo; Guan, Xiaohong; Fang, Jingyun; Tratnyek, Paul G

    2015-10-20

    MnO4(-) was activated by HSO3(-), resulting in a process that oxidizes organic contaminants at extraordinarily high rates. The permanganate/bisulfite (PM/BS) process oxidized phenol, ciprofloxacin, and methyl blue at pHini 5.0 with rates (kobs ≈ 60-150 s(-1)) that were 5-6 orders of magnitude faster than those measured for permanganate alone, and ∼5 to 7 orders of magnitude faster than conventional advanced oxidation processes for water treatment. Oxidation of phenol was fastest at pH 4.0, but still effective at pH 7.0, and only slightly slower when performed in tap water. A smaller, but still considerable (∼3 orders of magnitude) increase in oxidation rates of methyl blue was observed with MnO2 activated by HSO3(-) (MO/BS). The above results, time-resolved spectroscopy of manganese species under various conditions, stoichiometric analysis of pH changes, and the effect of pyrophosphate on UV absorbance spectra suggest that the reactive intermediate(s) responsible for the extremely rapid oxidation of organic contaminants in the PM/BS process involve manganese(III) species with minimal stabilization by complexation. The PM/BS process may lead to a new category of advanced oxidation technologies based on contaminant oxidation by reactive manganese(III) species, rather than hydroxyl and sulfate radicals.

  7. Permanganate-bromide-silver nanoparticles as a new chemiluminescence system and its application to captopril determination.

    PubMed

    Amjadi, Mohammad; Manzoori, Jamshid L; Hassanzadeh, Javad; Sorouraddin, Mohammad H

    2013-10-15

    A novel chemiluminescence (CL) system based on the oxidation of bromide by permanganate in sulfuric acid medium is introduced. The enhancing effect of silver nanoparticles (NPs), synthesized by chemical reduction method, on this reaction was studied. It was demonstrated that spherical silver nanoparticles with average size of 18 nm had a most remarkable catalytic effect on this reaction. CL emission wavelengths and UV-vis spectra were used to characterize the system and propose a possible mechanism. Furthermore, it was found that captopril inhibits the action of NPs and decreases the intensity of CL. Based on this phenomenon, a new CL method was developed for the determination of captopril in the 3.0 × 10(-10) to 1.0 × 10(-7) mol L(-1) concentration range with a detection limit (3s) of 0.12 nmol L(-1). The method was successfully applied to the determination of captopril in pharmaceutical formulations, human urine and serum samples. Copyright © 2013 Elsevier B.V. All rights reserved.

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

    NASA Astrophysics Data System (ADS)

    Fu, Congli; Liu, Shuling; Gong, Tianlong; Gu, Aiqun; Yu, Zili

    2014-10-01

    In the previous articles concerning the treatment of poly(tetrafluoroethylene) (PTFE) with potassium permanganate/nitric acid mixture, the conversion of a hydrophobic to a hydrophilic surface was partially assigned to the defluorination of PTFE and then the introduction of carbonyl and hydroxyl groups into the defluorinated sites. In the present work, PTFE sheets were treated with potassium permanganate/nitric acid, and the surfaces before and after treatment were comparatively characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The surface sediments of the treated PTFE were also determined by atomic absorption spectroscopy (AAS). The results indicate that the conversion of the hydrophobicity to the hydrophilicity on the modified PTFE surface is mainly due to the deposition of hydrophilic manganese oxides which covered the fluorocarbon surface, and no detectable chemical reactions of PTFE occur in the treating process.

  9. Reappraisal of potassium permanganate oxidation applied to Lowicryl K4M embedded tissues processed by high pressure freezing/freeze substitution, with special reference to differential staining of the zymogen granules of rat gastric chief cells.

    PubMed

    Sawaguchi, A; Ide, S; Kawano, J; Nagaike, R; Oinuma, T; Tojo, H; Okamoto, M; Suganuma, T

    1999-12-01

    The high pressure freezing/freeze substitution technique is known to yield a deep vitreous freezing of tissues. Combination of this technique with Lowicryl K4M embedding allows us histochemical studies of dynamic cellular processes with improved structural preservation. The disadvantage of Lowicryl K4M embedding is its poor electron density in electron microscopy. To address this problem, we examined the effects of KMnO4 oxidation applied to Lowicryl K4M embedded rat gastric glands processed by high pressure freezing. The KMnO4 oxidation-uranyl acetate-lead citrate sequence succeeded not only in contrast enhancement of cellular components, but also in differential staining of the zymogen granules of rat gastric chief cells. This technique could be applied to semi-thin sections of Lowicryl K4M embedded rat gastric glands. The KMnO4 oxidation-toluidine blue staining provided sufficient contrast with regard to the zymogen granules. Various experiments used in this study verified that the KMnO4 oxidation plays an essential role in the differential staining of the zymogen granules. Combined use of the KMnO4 oxidation with phospholipase A2-immunostaining demonstrated that gold labeling was localized to the zymogen granules without the loss of immunolabeling. Energy dispersive X-ray microanalysis revealed some manganese depositions on the zymogen granules. It is highly anticipated that the KMnO4 oxidation will become a useful tool for histochemical investigations combined with cryofixation/freeze substitution and low temperature embedding techniques.

  10. Potassium permanganate for mercury vapor environmental control

    NASA Technical Reports Server (NTRS)

    Kuivinen, D. E.

    1972-01-01

    Potassium permanganate (KMnO4) was evaluated for application in removing mercury vapor from exhaust air systems. The KMnO4 may be used in water solution with a liquid spray scrubber system or as a solid adsorber bed material when impregnated onto a zeolite. Air samples contaminated with as much as 112 mg/cu m of mercury were scrubbed to 0.06mg/cum with the KMnO4-impregnated zeolite (molecular sieve material). The water spray solution of permanganate was also found to be as effective as the impregnated zeolite. The KMnO4-impregnated zeolite was applied as a solid adsorber material to (1) a hardware decontamination system, (2) a model incinerator, and (3) a high vacuum chamber for ion engine testing with mercury as the propellant. A liquid scrubber system was also applied in an incinerator system. Based on the results of these experiments, it is concluded that the use of KMnO4 can be an effective method for controlling noxious mercury vapor.

  11. Two-phase titration of cerium(III) by permanganate

    SciTech Connect

    Lazarev, A.I.; Lazareva, V.I.; Gerko, V.V.

    1987-02-01

    This paper presents a method for the two-phase titrimetric determination of cerium(III) with permanganate which does not require an expenditure of sugar and preliminary removal of chlorides and nitrates. The interaction of cerium(III) with permanganate at room temperature was studied as a function of the pH, the concentration of pyrophosphate, tetraphenylphosphonium (TPP), permanganate, and extraneous compounds, the rate of titration, and the time of stay of the solution in air before titration. The investigations were conducted according to the following methodology: water, solution of cerium(III) pyrophosphate, and TPP were introduced into an Erlenmeyer flask with a side branch near the bottom for clearer observation of the color of the chloroform phase. The authors established the given pH value, poured the water into a volume of 50 ml, and added chloroform. The result was titrated with permanganate solutions of various concentrations until a violet color appeared in the chloroform phase.

  12. Enhanced biogenic emissions of nitric oxide and nitrous oxide following surface biomass burning

    Treesearch

    Iris C. Anderson; Joel S. Levine; Mark A. Poth; Philip J. Riggan

    1988-01-01

    Recent measurements indicate significantly enhanced biogenic soil emissions of both nitric oxide (NO) and nitrous oxide (N2O) following surface burning. These enhanced fluxes persisted for at least 6 months following the burn. Simultaneous measurements indicate enhanced levels of...

  13. [Study of relationship between consumption of potassium permanganate and total organic carbon on plastic kitchen utensils, food packages and toys].

    PubMed

    Ohno, Hiroyuki; Suzuki, Masako; Mutsuga, Motoh; Kawamura, Yoko

    2009-10-01

    Consumption of potassium permanganate and total organic carbon (TOC) were investigated as indices of total organic matter migrated into water from plastic kitchen utensils, food packages and toys for children. The samples were soaked in water at 60 or 95 degrees C for 30 min for kitchen utensils and food packages, and at 40 degrees C for 30 min for toys and the eluates were examined, using the two indices. The quantitation limits were both 0.5 microg/mL. Among 97 kitchen utensils and food packages tested, consumption of potassium permanganate and TOC were 0.5-10.9 microg/mL and ND-18.9 microg/mL for polyvinyl chloride (PVC) tea-pot spouts and nylon kitchen utensils, respectively. Among 32 toys tested, the levels were 0.8-45.5 microg/mL and 0.5-8.9 microg/mL from PVC toys and block toys made by ethylene vinyl acetate resin. The levels for other samples were very low. There were large discrepancies between consumption of potassium permanganate and TOC for some PVC products and nylon kitchen utensils. The cause may be a marked difference of the oxidation decomposition rate by potassium permanganate, depending on the kind of organic matter that migrated from the plastics.

  14. Enhanced coal hydrogasification via oxidative pretreatment

    SciTech Connect

    Miller, D.J.

    1992-04-16

    The gasification of coal char by hydrogen is much slower than in steam or carbon dioxide; moreover, hydrogasification rate in pure hydrogen decreases sharply with conversion for most carbons. To overcome this kinetic behavior, the oxidation of the char prior to and during hydrogasification has been investigated as a means of enhancing hydro gasification rate. Kinetic rate studies under well-characterized conditions have been complemented by careful surface analyses to characterize oxygen on the char surface prior to and during hydrogasification.

  15. Individual Reactions of Permanganate and Various Reductants - Student Report to the DOE ERULF Program for Work Conducted May to July 2000

    SciTech Connect

    Gauger, Amber M.; Hallen, Richard T.

    2012-09-15

    Tank waste on the Hanford Site contains radioactive elements that need to be removed from solution prior to disposal. One effective way to do this is to precipitate the radioactive elements with manganese solids, produced by permanganate oxidation. When added to tank waste, the permanganate reacts quickly producing manganese (IV) dioxide precipitate. Because of the speed of the reaction it is difficult to tell what exactly is happening. Individual reactions using non-radioactive reductants found in the tanks were done to determine reaction kinetics, what permanganate was reduced to, and what oxidation products were formed. In this project sodium formate, sodium nitrite, glycolic acid, glycine, and sodium oxalate were studied using various concentrations of reductant in alkaline sodium hydroxide solutions. It was determined that formate reacted the quickest, followed by glycine and glycolic acid. Oxalate and nitrite did not appear to react with the permanganate solutions. The products of the oxidation reaction were examined. Formate was oxidized to carbonate and water. Glycolic acid was oxidized slower producing oxalate and water. Glycine reactions formed some ammonia in solution, oxalate, and water. The research reported by Amber Gauger in this report was part of a DOE ERULF student intern program at Pacific Northwest National Laboratory under the direction of Richard Hallen in the summer of 2000.

  16. (Enhanced coal hydrogasification via oxidative pretreatment)

    SciTech Connect

    Not Available

    1990-01-01

    Work continued on coal hydrogasification. To date, twenty-one gasification runs have been conducted. These runs have focused on (1) obtaining a representative set of partially converted samples with which to determine pore structure and surface area development, (2) determining suitable conditions for the kinetic studies and (3) illustrating rate enhancement following oxidation. Also, ultimate-proximate analyses of the three samples were conducted at a commercial analytical laboratory. The high oxygen content of demineralized char is as yet unexplained. 6 figs., 2 tabs.

  17. Slow-release Permanganate Gel (SRP-G) for Groundwater Remediation: Spreading, Gelation, and Release in Porous and Low-Permeability Media

    NASA Astrophysics Data System (ADS)

    Lee, E. S.; Hastings, J.; Kim, Y.

    2015-12-01

    Dense nonaqueous phase liquids (DNAPLs) like trichloroethylene (TCE) serve as the most common form of groundwater pollution in the world. Pore-plugging by the solid oxidation product MnO2 and limited lateral dispersion of the oxidant are two common problems with existing in-situ chemical oxidation (ISCO) schemes that could be alleviated through the development of a delayed gelation method for oxidant delivery. The objective of the current study was to further develop and optimize slow-release permanganate gel (SRP-G), a solution comprising colloidal silica and KMnO4, as a novel low-cost treatment option for large and dilute TCE plumes in groundwater. Batch tests showed that gelation could be delayed through manipulation of KMnO4 concentration, pH, and silica particle size of the SRP-G solution. In flow-through columns and flow-tanks filled with saturated sands, silica concentration had little effect on the gelation lag stage and release rate, but increasing silica concentration was associated with increasing release duration. When compared to a pure KMnO4 solution, visual observations and [MnO4-] measurements from flow tank tests demonstrated that the SRP-G prolonged the release duration and enhanced lateral spreading of the oxidant.

  18. 21 CFR 250.108 - Potassium permanganate preparations as prescription drugs.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 4 2014-04-01 2014-04-01 false Potassium permanganate preparations as... or Prescription Status of Specific Drugs § 250.108 Potassium permanganate preparations as... women resulting from the misuse of potassium permanganate in an effort to induce abortion. Reports...

  19. Iron oxide nanoparticle enhancement of radiation cytotoxicity

    NASA Astrophysics Data System (ADS)

    Mazur, Courtney M.; Tate, Jennifer A.; Strawbridge, Rendall R.; Gladstone, David J.; Hoopes, P. Jack

    2013-02-01

    Iron oxide nanoparticles (IONPs) have been investigated as a promising means for inducing tumor cell-specific hyperthermia. Although the ability to generate and use nanoparticles that are biocompatible, tumor specific, and have the ability to produce adequate cytotoxic heat is very promising, significant preclinical and clinical development will be required for clinical efficacy. At this time it appears using IONP-induced hyperthermia as an adjunct to conventional cancer therapeutics, rather than as an independent treatment, will provide the initial IONP clinical treatment. Due to their high-Z characteristics, another option is to use intracellular IONPs to enhance radiation therapy without excitation with AMF (production of heat). To test this concept IONPs were added to cell culture media at a concentration of 0.2 mg Fe/mL and incubated with murine breast adenocarcinoma (MTG-B) cells for either 48 or 72 hours. Extracellular iron was then removed and all cells were irradiated at 4 Gy. Although samples incubated with IONPs for 48 hrs did not demonstrate enhanced post-irradiation cytotoxicity as compared to the non-IONP-containing cells, cells incubated with IONPs for 72 hours, which contained 40% more Fe than 48 hr incubated cells, showed a 25% decrease in clonogenic survival compared to their non-IONP-containing counterparts. These results suggest that a critical concentration of intracellular IONPs is necessary for enhancing radiation cytotoxicity.

  20. Kinetic determination of acarbose and miglitol in bulk and pharmaceutical formulations using alkaline potassium permanganate.

    PubMed

    Ibrahim, F A; Ali, F A; Ahmed, S M; Tolba, M M

    2007-03-01

    A simple and sensitive kinetic spectrophotometric method was established for the determination of acarbose and miglitol in bulk and in their pharmaceutical preparations using alkaline potassium permanganate as an oxidizing agent. The method involves determination of acarbose and miglitol by kinetic studies of their oxidation at room temperature for a fixed time of 15 minutes for acarbose and 25 minutes for miglitol. The absorbance of the colored manganate ion was measured at 610 nm. Alternatively, the kinetic decrease in the absorbance of permanganate upon addition of the studied drugs at 525 nm was also used. The absorbance concentration plot was rectilinear over the concentration range of 4-20 and 1-10 μg/ml for acarbose and miglitol, respectively. The detection limits were 0.189 and 0.089 μg/ml at 610 nm and 0.081 and 0.179 μg/ml at 525 nm for acarbose and miglitol respectively. The method was successfully applied for the determination of these drugs in their dosage forms. The results obtained were in good agreement with those obtained with the reference methods.

  1. Kinetic Determination of Acarbose and Miglitol in Bulk and Pharmaceutical Formulations Using Alkaline Potassium Permanganate

    PubMed Central

    Ibrahim, F. A.; Ali, F. A.; Ahmed, S. M.; Tolba, M. M.

    2007-01-01

    A simple and sensitive kinetic spectrophotometric method was established for the determination of acarbose and miglitol in bulk and in their pharmaceutical preparations using alkaline potassium permanganate as an oxidizing agent. The method involves determination of acarbose and miglitol by kinetic studies of their oxidation at room temperature for a fixed time of 15 minutes for acarbose and 25 minutes for miglitol. The absorbance of the colored manganate ion was measured at 610 nm. Alternatively, the kinetic decrease in the absorbance of permanganate upon addition of the studied drugs at 525 nm was also used. The absorbance concentration plot was rectilinear over the concentration range of 4-20 and 1-10 μg/ml for acarbose and miglitol, respectively. The detection limits were 0.189 and 0.089 μg/ml at 610 nm and 0.081 and 0.179 μg/ml at 525 nm for acarbose and miglitol respectively. The method was successfully applied for the determination of these drugs in their dosage forms. The results obtained were in good agreement with those obtained with the reference methods. PMID:23675017

  2. Gold-enhanced oxidation of MBE-grown silicon nanowires

    NASA Astrophysics Data System (ADS)

    Büttner, C. C.; Zakharov, N. D.; Pippel, E.; Gösele, U.; Werner, P.

    2008-07-01

    Thermal oxidation of MBE-grown silicon nanowires with a gold droplet on their tips was investigated. Two kinds of oxidation behavior were observed: (i) enhanced axial oxidation, if there was a direct contact between the gold droplet and the nanowire, and (ii) conventional oxidation for nanowires when there was no direct contact between the gold and silicon. For a dry atmosphere, such enhanced oxidation takes place at temperatures down to 500 °C. Under a wet atmosphere, remarkable oxidation was observed even for temperatures down to 250 °C.

  3. Quantification of soil permanganate oxidizable c (poxc) using infrared spectroscopy

    USDA-ARS?s Scientific Manuscript database

    Labile soil carbon is an important component of soil organic matter because it embodies the mineralizable material that is associated with short-term fertility and responds to management practices. Permanganate-oxidizable C (POXC) is a widely used method for the study of labile C dynamics in soils. ...

  4. Cyanobacterial Treatment Options: Permanganate and Powdered Activated Carbon

    EPA Science Inventory

    This presentation will begin with a brief overview of drinking water treatment options for cyanobacteria and their toxins. The treatment discussion will focus on the impacts of permanganate addition to suspensions of toxin-producing Microcystis aeruginosa, followed by powdered ac...

  5. Spectrophotometric Determination of Pipazethate HCl and Dextromethorphan HBr using Potassium Permanganate.

    PubMed

    Gouda, Ayman Abou El-Fetouh; El-Sheikh, Ragaa; El Shafey, Zeineb; Hossny, Nagda; El-Azzazy, Rham

    2008-12-01

    Rapid, simple and sensitive validated spectrophotometric methods have been described for the assay of pipazethate HCl (PiCl) and dextromethorphan HBr (DEX) either in pure form or in pharmaceutical formulations. The proposed methods were based on the oxidation of the studied drugs by a known excess of potassium permanganate in acidic medium and estimating the unreacted permanganate with amaranth dye (method A), acid orange II (method B), indigocarmine (method C) and methylene blue (method D), in the same acid medium at a suitable λmax=521, 485, 610 and 664 nm, respectively. Beer's law is obeyed in the concentration range of 2.0-16 and 2.0-15 μg mL(-1) for PiCl and DEX, respectively with correlation coefficient (n=6) ≥ 0.9993. The apparent molar absorptivity and sandell sensitivity values are in the range 1.062-1.484 × 10(4), 3.35-4.51 × 10(4) L mol(-1) cm(-1) and 29.36-41.03, 8.21-11.06 ng cm(-2) for PiCl and DEX, respectively. Different variables affecting the reaction were studied and optimized. The proposed methods were applied successfully to the determination of the examined drugs either in a pure or pharmaceutical dosage forms with good accuracy and precision. No interferences were observed from excipients and the results obtained were in good agreement with those obtained using the official methods.

  6. Sensitive and selective determination of fluvoxamine maleate using a sensitive chemiluminescence system based on the alkaline permanganate-Rhodamine B-gold nanoparticles reaction.

    PubMed

    Hassanzadeh, Javad; Amjadi, Mohammad

    2015-06-01

    A high-yield chemiluminescence (CL) system based on the alkaline permanganate-Rhodamine B reaction was developed for the sensitive determination of fluvoxamine maleate (Flu). Rhodamine B is oxidized by alkaline KMnO4 and a weak CL emission is produced. It was demonstrated that gold nanoparticles greatly enhance this CL emission due to their interaction with Rhodamine B molecules. It is also observed that sodium dodecyl sulfate, an anionic surfactant, can strongly increase this enhancement. In addition, it was demonstrated that a notable decrease in the CL intensity is observed in the presence of Flu. This may be related to Flu oxidation with KMnO4 . There is a linear relationship between the decrease in CL intensity and the Flu concentration over a range of 2-300 µg/L. A new simple, rapid and sensitive CL method was developed for the determination of Flu with a detection limit (3s) of 1.35 µg/L. The proposed method was used for the determination of Flu in pharmaceutical and urine samples.

  7. Microwave enhanced oxidation treatment of organic fertilizers.

    PubMed

    More, Abhilasha; Srinivasan, Asha; Liao, Ping Huang; Lo, Kwang Victor

    2017-08-01

    Liquid organic fertilizers (LOFs) are relatively easier to degrade than those of solid organic fertilizers, and the nutrients are readily available for plant uptake. Microwave enhanced advanced oxidation treatment (MW/H2 O2 -AOP) was used to convert solid organic fertilizers (insoluble blood meal, bone meal, feather meal, sunflower ash and a mixture) into LOF. After the MW/H2 O2 -AOP treatment, high soluble nitrogen (11-29%), soluble phosphorus (64%) and potassium (92%), as well as low total suspended solids content could be obtained. The resulting LOF would make the nutrients more bioavailable, and would provide some of them for the plant uptake immediately. Temperature and hydrogen peroxide dosage were found to be significant factors affecting nitrogen release from blood meal and feather meal, while temperature and pH were found to be significant factors for solubilizing phosphorus and potassium from bone meal and ash, respectively. The MW/H2 O2 -AOP reduced suspended solids, and released nutrients into solution; therefore, it was an effective treatment method to make LOFs. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  8. LABORATORY STUDY ON THE OXIDATION OF ARSENIC III TO ARSENIC V

    EPA Science Inventory

    A one-year laboratory study was performed to determine the ability of seven oxidants to oxidize As(III) to As(V). These included chlorine, permanganate, ozone, chlorine dioxide, monochloramine, a solid-phase oxidizing media, and 254 nm ultraviolet light. Chlorine and permanganate...

  9. LABORATORY STUDY ON THE OXIDATION OF ARSENIC III TO ARSENIC V

    EPA Science Inventory

    A one-year laboratory study was performed to determine the ability of seven oxidants to oxidize As(III) to As(V). These included chlorine, permanganate, ozone, chlorine dioxide, monochloramine, a solid-phase oxidizing media, and 254 nm ultraviolet light. Chlorine and permanganate...

  10. General and efficient one-pot synthesis of novel sugar/heterocyclic(aryl) 1,2-diketones from sugar terminal alkynes by Sonogashira/tetra-n- butylammonium permanganate oxidation.

    PubMed

    Zhang, Fuyi; Wu, Xiaopei; Wang, Liming; Liu, Hong; Zhao, Yufen

    2015-11-19

    A new approach for one-pot synthesis of novel sugar/heterocyclic(aryl) 1,2-diketones has been achieved by the reaction of various sugar terminal alkynes with heterocyclic(aryl) iodides at room temperature. This one-pot protocol includes Sonogashira coupling and mild n-Bu4NMnO4 oxidation reaction. This method is mild, general and efficient. Fifty-six examples have been given and the sugar/heterocyclic(aryl) 1,2-diketones were obtained in 71-94% yields. The sugar terminal alkynes include 9 structurally different sugars in pyranose, furanose, and acyclic form which have various protecting groups, sensitive groups, and sterically bulky substituents. The heterocyclic(aryl) iodides include sterically bulky heterocyclic compounds and iodobenzenes with electron-donating, electron-neutral, and electron-withdrawing substituents.

  11. Solubility Enhanced Oxidation of Hydrophobic Organic Contaminants

    NASA Astrophysics Data System (ADS)

    Boving, T. B.; Eberle, D. E.; Ball, R.

    2012-12-01

    In-situ chemical oxidation (ISCO) is a remediation technique considered to be effective at overcoming some of the limitations of conventional subsurface treatment processes for volatile and semi-volatile organic contaminants (VOC, SVOC). ISCO reactions occur predominately in the aqueous phase and as a result, contaminant availability is a major limiting factor, i.e. contaminants with higher aqueous solubility's are typically more accessible for oxidation than more hydrophobic, sorbed compounds. The purpose of this study was to determine the feasibility of a new integrated desorption-oxidation process for the remediation of contaminated waters and sediments. Specifically, this study examined the potential of using hydroxypropyl-β-cyclodextrin (HPCD), a modified cyclic sugar, and a blend of oxidants commercially known as OxyZone® (U.S. patent No. 7,667,087) for the remediation of polycyclic aromatic hydrocarbons (PAH). Laboratory scale batch experiments confirmed prior studies that HPCD increases the aqueous concentration of these contaminants, making a greater mass of contaminant available for subsequent oxidation. When exposed to the same amount of oxidant, the mass of PAH destroyed increased linearly with increasing HPCD concentration. Relative to PAH saturated solutions without HPCD, 11 times more PAH mass was destroyed when a PAH saturated 15 g/L HPCD solution was treated with the same mass of oxidant. Destruction of the aqueous phase contaminants followed first order exponential decay kinetics in both deionized water and HPCD solutions. However, the destruction of complexed PAH was slower than for uncomplexed PAH. The cause of this is likely due to the preferential destruction of the HPCD molecule by the oxidant, followed by the subsequent oxidation of the PAH. The destruction of the cyclodextrin was minimized by modifying the oxidant formulation. Overall, these findings establish the potential of utilizing HPCD and OxyZone® as an integrated desorption-oxidation

  12. In Situ Electrochemical Oxidation Tuning of Transition Metal Disulfides to Oxides for Enhanced Water Oxidation

    PubMed Central

    2015-01-01

    The development of catalysts with earth-abundant elements for efficient oxygen evolution reactions is of paramount significance for clean and sustainable energy storage and conversion devices. Our group demonstrated recently that the electrochemical tuning of catalysts via lithium insertion and extraction has emerged as a powerful approach to improve catalytic activity. Here we report a novel in situ electrochemical oxidation tuning approach to develop a series of binary, ternary, and quaternary transition metal (e.g., Co, Ni, Fe) oxides from their corresponding sulfides as highly active catalysts for much enhanced water oxidation. The electrochemically tuned cobalt–nickel–iron oxides grown directly on the three-dimensional carbon fiber electrodes exhibit a low overpotential of 232 mV at current density of 10 mA cm–2, small Tafel slope of 37.6 mV dec–1, and exceptional long-term stability of electrolysis for over 100 h in 1 M KOH alkaline medium, superior to most non-noble oxygen evolution catalysts reported so far. The materials evolution associated with the electrochemical oxidation tuning is systematically investigated by various characterizations, manifesting that the improved activities are attributed to the significant grain size reduction and increase of surface area and electroactive sites. This work provides a promising strategy to develop electrocatalysts for large-scale water-splitting systems and many other applications. PMID:27162978

  13. In Situ Electrochemical Oxidation Tuning of Transition Metal Disulfides to Oxides for Enhanced Water Oxidation

    DOE PAGES

    Chen, Wei; Wang, Haotian; Li, Yuzhang; ...

    2015-07-15

    The development of catalysts with earth-abundant elements for efficient oxygen evolution reactions is of paramount significance for clean and sustainable energy storage and conversion devices. Our group demonstrated recently that the electrochemical tuning of catalysts via lithium insertion and extraction has emerged as a powerful approach to improve catalytic activity. Here we report a novel in situ electrochemical oxidation tuning approach to develop a series of binary, ternary, and quaternary transition metal (e.g., Co, Ni, Fe) oxides from their corresponding sulfides as highly active catalysts for much enhanced water oxidation. The electrochemically tuned cobalt–nickel–iron oxides grown directly on the three-dimensionalmore » carbon fiber electrodes exhibit a low overpotential of 232 mV at current density of 10 mA cm–2, small Tafel slope of 37.6 mV dec–1, and exceptional long-term stability of electrolysis for over 100 h in 1 M KOH alkaline medium, superior to most non-noble oxygen evolution catalysts reported so far. The materials evolution associated with the electrochemical oxidation tuning is systematically investigated by various characterizations, manifesting that the improved activities are attributed to the significant grain size reduction and increase of surface area and electroactive sites. This work provides a promising strategy to develop electrocatalysts for large-scale water-splitting systems and many other applications.« less

  14. On-line derivatization coupled to flow injection permanganate chemiluminescence detection of total carbonyl compounds in natural waters and drinking water.

    PubMed

    Giokas, Dimosthenis L; Tsogas, George Z; Vlessidis, Athanasios G

    2009-10-05

    This work describes the development of a fast assay for the determination of low molecular weight carbonyl compounds based on the oxidative chemiluminescence of 2,4-dinitrophenylhydrazine with acidic permanganate, which is enhanced during conversion to the corresponding phenylhydrazone-carbonyl derivatives. By exploiting the common derivatization pathway and oxidation mechanism of phenylhydrazones under kinetically controlled conditions in a flow configuration, a common light emission is produced which corresponds to the total aqueous concentration of carbonyl compounds. The experimental conditions that afford the optimum analytical features were optimized for acetone, acetaldehyde and formaldehyde which constitute the most abundant carbonyl compounds in environmental samples. The method was successfully applied to the determination of total carbonyl content in natural waters and drinking water at the low microg L(-1) levels with satisfactory recoveries (94.0-99.5%) and very good reproducibility (RSD=1.58-2.99%, n=8, C=2 microg L(-1)). Validation of the results was performed with gas chromatography suggesting that the proposed method provides a fast alternative to the routine screening of low molecular weight carbonyl compounds in natural waters.

  15. VALIDATION FOR THE PERMANGANATE DIGESTION OF REILLEX HPQ ANION RESIN

    SciTech Connect

    Kyser, E.

    2009-09-23

    The flowsheet for the digestion of Reillex{trademark} HPQ was validated both under the traditional alkaline conditions and under strongly acidic conditions. Due to difficulty in performing a pH adjustment in the large tank where this flowsheet must be performed, the recommended digestion conditions were changed from pH 8-10 to 8 M HNO{sub 3}. Thus, no pH adjustment of the solution is required prior to performing the permanganate addition and digestion and the need to sample the digestion tank to confirm appropriate pH range for digestion may be avoided. Neutralization of the acidic digestion solution will be performed after completion of the resin digestion cycle. The amount of permanganate required for this type of resin (Reillex{trademark} HPQ) was increased from 1 kg/L resin to 4 kg/L resin to reduce the amount of residual resin solids to a minimal amount (<5%). The length of digestion time at 70 C remains unchanged at 15 hours. These parameters are not optimized but are expected to be adequate for the conditions. The flowsheet generates a significant amount of fine manganese dioxide (MnO{sub 2}) solids (1.71 kg/L resin) and involves the generation of a significant liquid volume due to the low solubility of permanganate. However, since only two batches of resin (40 L each) are expected to be digested, the total waste generated is limited.

  16. Enhanced oxidation resistance of active nanostructures via dynamic size effect

    NASA Astrophysics Data System (ADS)

    Liu, Yun; Yang, Fan; Zhang, Yi; Xiao, Jianping; Yu, Liang; Liu, Qingfei; Ning, Yanxiao; Zhou, Zhiwen; Chen, Hao; Huang, Wugen; Liu, Ping; Bao, Xinhe

    2017-02-01

    A major challenge limiting the practical applications of nanomaterials is that the activities of nanostructures (NSs) increase with reduced size, often sacrificing their stability in the chemical environment. Under oxidative conditions, NSs with smaller sizes and higher defect densities are commonly expected to oxidize more easily, since high-concentration defects can facilitate oxidation by enhancing the reactivity with O2 and providing a fast channel for oxygen incorporation. Here, using FeO NSs as an example, we show to the contrary, that reducing the size of active NSs can drastically increase their oxidation resistance. A maximum oxidation resistance is found for FeO NSs with dimensions below 3.2 nm. Rather than being determined by the structure or electronic properties of active sites, the enhanced oxidation resistance originates from the size-dependent structural dynamics of FeO NSs in O2. We find this dynamic size effect to govern the chemical properties of active NSs.

  17. The role of protective scales in enhancing oxidation resistance

    SciTech Connect

    Smith, G.D.

    1996-12-01

    There has been steady progress in the development of wrought nickel-containing alloys for use in high temperature oxidizing environments. Contributing significantly to this progress is a growing knowledge base on the role of scales in enhancing oxidation resistance. Future improvements in oxidation resistance must build upon this understanding. This paper seeks to survey a portion of the wealth of information regarding scale characteristics of commercial wrought nickel-containing alloys and how scales are influenced by environment and alloy composition. Some suggestions as to the future direction of alloy development with regard to scale optimization and increased oxidation resistance are proposed.

  18. Kinetics of membrane damage to high (HNA) and low (LNA) nucleic acid bacterial clusters in drinking water by ozone, chlorine, chlorine dioxide, monochloramine, ferrate(VI), and permanganate.

    PubMed

    Ramseier, Maaike K; von Gunten, Urs; Freihofer, Pietro; Hammes, Frederik

    2011-01-01

    Drinking water was treated with ozone, chlorine, chlorine dioxide, monochloramine, ferrate(VI), and permanganate to investigate the kinetics of membrane damage of native drinking water bacterial cells. Membrane damage was measured by flow cytometry using a combination of SYBR Green I and propidium iodide (SGI+PI) staining as indicator for cells with permeabilized membranes and SGI alone to measure total cell concentration. SGI+PI staining revealed that the cells were permeabilized upon relatively low oxidant exposures of all tested oxidants without a detectable lag phase. However, only ozonation resulted in a decrease of the total cell concentrations for the investigated reaction times. Rate constants for the membrane damage reaction varied over seven orders of magnitude in the following order: ozone > chlorine > chlorine dioxide ≈ ferrate > permanganate > chloramine. The rate constants were compared to literature data and were in general smaller than previously measured rate constants. This confirmed that membrane integrity is a conservative and therefore safe parameter for disinfection control. Interestingly, the cell membranes of high nucleic acid (HNA) content bacteria were damaged much faster than those of low nucleic acid (LNA) content bacteria during treatment with chlorine dioxide and permanganate. However, only small differences were observed during treatment with chlorine and chloramine, and no difference was observed for ferrate treatment. Based on the different reactivity of these oxidants it was suggested that HNA and LNA bacterial cell membranes have a different chemical constitution.

  19. Polymer-Enhanced Subsurface Delivery and Distribution of Permanganate

    DTIC Science & Technology

    2013-02-01

    on the November 2009 depth-to-water measurements. 17 A pneumatic slug test method was employed through direct push technology (DPT). Steel ...used to measure the volume of water added. 26 Xanthan gum and SHMP were introduced as dry powders to the stainless steel hopper that was mounted...separation distance. GMS could not provide a cylindrical grid space. Therefore, a square (or cube ) grid space (dimensions: X=28 ft, y=28 ft, z=-35 ft

  20. Polymer-Enhanced Subsurface Delivery and Distribution of Permanganate

    DTIC Science & Technology

    2013-02-01

    November and December 2009. A pneumatic slug test method was employed through DPT-installed steel rod piezometers at three locations across the test...geologically logged from ground surface to the total depth of the well. Injection wells were constructed with 4-inch diameter stainless steel screens (20...preparation tank to the primary storage tank). The polymer mixing unit consisted of a stainless steel hopper, educator, an internal shearing device, and a

  1. 75 FR 65448 - Potassium Permanganate From the People's Republic of China: Continuation of Antidumping Duty Order

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-25

    ... International Trade Administration Potassium Permanganate From the People's Republic of China: Continuation of... the antidumping duty order on potassium permanganate from the People's Republic of China (``PRC... published the notice of initiation of the sunset review of the antidumping duty order on potassium...

  2. 75 FR 52509 - Potassium Permanganate from the People's Republic of China: Final Results of Expedited Sunset...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-26

    ... International Trade Administration Potassium Permanganate from the People's Republic of China: Final Results of... Department of Commerce (``Department'') initiated a sunset review of the antidumping duty order on potassium... initiation of the sunset review of the antidumping duty order on potassium permanganate from the PRC pursuant...

  3. 21 CFR 250.108 - Potassium permanganate preparations as prescription drugs.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... women resulting from the misuse of potassium permanganate in an effort to induce abortion. Reports from... potassium permanganate is not effective in producing abortion, but that instead the drug produces serious... that the article would be used in an attempt to induce abortion. (4) Any preparation of...

  4. Effect of Rap1 binding on DNA distortion and potassium permanganate hypersensitivity.

    PubMed

    Le Bihan, Yann-Vaï; Matot, Béatrice; Pietrement, Olivier; Giraud-Panis, Marie-Josèphe; Gasparini, Sylvaine; Le Cam, Eric; Gilson, Eric; Sclavi, Bianca; Miron, Simona; Le Du, Marie-Hélène

    2013-03-01

    Repressor activator protein 1 (Rap1) is an essential factor involved in transcription and telomere stability in the budding yeast Saccharomyces cerevisiae. Its interaction with DNA causes hypersensitivity to potassium permanganate, suggesting local DNA melting and/or distortion. In this study, various Rap1-DNA crystal forms were obtained using specifically designed crystal screens. Analysis of the DNA conformation showed that its distortion was not sufficient to explain the permanganate reactivity. However, anomalous data collected at the Mn edge using a Rap1-DNA crystal soaked in potassium permanganate solution indicated that the DNA conformation in the crystal was compatible with interaction with permanganate ions. Sequence-conservation analysis revealed that double-Myb-containing Rap1 proteins all carry a fully conserved Arg580 at a position that may favour interaction with permanganate ions, although it is not involved in the hypersensitive cytosine distortion. Permanganate reactivity assays with wild-type Rap1 and the Rap1[R580A] mutant demonstrated that Arg580 is essential for hypersensitivity. AFM experiments showed that wild-type Rap1 and the Rap1[R580A] mutant interact with DNA over 16 successive binding sites, leading to local DNA stiffening but not to accumulation of the observed local distortion. Therefore, Rap1 may cause permanganate hypersensitivity of DNA by forming a pocket between the reactive cytosine and Arg580, driving the permanganate ion towards the C5-C6 bond of the cytosine.

  5. 21 CFR 250.108 - Potassium permanganate preparations as prescription drugs.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... women resulting from the misuse of potassium permanganate in an effort to induce abortion. Reports from... potassium permanganate is not effective in producing abortion, but that instead the drug produces serious... that the article would be used in an attempt to induce abortion. (4) Any preparation of...

  6. 21 CFR 250.108 - Potassium permanganate preparations as prescription drugs.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... women resulting from the misuse of potassium permanganate in an effort to induce abortion. Reports from... potassium permanganate is not effective in producing abortion, but that instead the drug produces serious... that the article would be used in an attempt to induce abortion. (4) Any preparation of...

  7. Exciton-Plasmon Coupling Enhancement via Metal Oxidation.

    PubMed

    Todisco, Francesco; D'Agostino, Stefania; Esposito, Marco; Fernández-Domínguez, Antonio I; De Giorgi, Milena; Ballarini, Dario; Dominici, Lorenzo; Tarantini, Iolena; Cuscuná, Massimo; Della Sala, Fabio; Gigli, Giuseppe; Sanvitto, Daniele

    2015-10-27

    In this paper, we report on the effect of metal oxidation on strong coupling interactions between silver nanostructures and a J-aggregated cyanine dye. We show that metal oxidation can sensibly affect the plexcitonic system, inducing a change in the coupling strength. In particular, we demonstrate that the presence of oxide prevents the appearance of Rabi splitting in the extinction spectra for thick spacers. In contrast, below a threshold percentage, the oxide layer results in an higher coupling strength between the plasmon and the Frenkel exciton. Contrary to common belief, a thin oxide layer seems thus to act, under certain conditions, as a coupling mediator between an emitter and a localized surface plasmon excited in a metallic nanostructure. This suggests that metal oxidation can be exploited as a means to enhance light-matter interactions in strong coupling applications.

  8. Emergency Do Not Consume/do Not Use concentrations for potassium permanganate in drinking water.

    PubMed

    Willhite, C C; Bhat, V S; Ball, G L; McLellan, C J

    2013-03-01

    Over the past decade, regulatory authorities and water purveyors have become increasingly concerned with accidental or intentional adulteration of municipal drinking water. Emergency response guidelines, such as the 'Do Not Consume' or use concentration limits derived herein, can be used to notify the public in such cases. Potassium permanganate (KMnO(4)) is used to control iron concentrations and to reduce the levels of nuisance materials that affect odor or taste of finished drinking water. Manganese (Mn) is recognized an essential nutrient, permanganate (MnO4 (-)) and manganous (Mn(+2)) ions are caustic, and the acute toxicity of KMnO(4) is defined by its oxidant/irritant properties and by the toxicity of Mn. Ingestion of small amounts (4-20 mg/kg) of aqueous KMnO(4) solutions that are above 200 mg/L causes gastrointestinal distress, while bolus ingestion has caused respiratory arrest following coagulative necrosis and hemorrhage in the esophagus, stomach, or liver. Dilute KMnO(4) solutions (1-100 mg/L) are used as a topical antiseptics and astringents, but >1:5000 (200 mg/L) dilutions can irritate or discolor sensitive mucous membranes and direct skin or ocular contact with concentrated KMnO(4) can perforate tissues. Based on clinical experience with 200 mg/L KMnO(4), a Do Not Consume concentration of 7 mg/L KMnO(4) (equivalent to 2 mg Mn/L) is recommended. Recognizing limited empirical data from which to calculate an ocular reference value, a skin contact 'Do Not Use' concentration of 30 mg Mn/L is recommended based on the skin irritation in some patients after a 10-min contact with 100 mg KMnO4/L.

  9. Nitric Oxide Enhances Charge-Coupled Device

    NASA Technical Reports Server (NTRS)

    Hecht, Michael H.; Poindexter, Edward H.

    1990-01-01

    Simple treatment increases and stabilizes quantum efficiency of charge-coupled-device photodetector illuminated on back surface at wavelengths less than 4,500 Angstrom. Must be biased in strong accumulation mode. Physical principle of enhancement explained more fully in "Metal Film Increases CCD Output" (NPO-16815). Useful for imaging at wavelengths from ultraviolet to blue; for example, in astronomical observations.

  10. Enhanced biogenic emissions of nitric oxide and nitrous oxide following surface biomass burning

    NASA Technical Reports Server (NTRS)

    Anderson, Iris C.; Levine, Joel S.; Poth, Mark A.; Riggan, Philip J.

    1988-01-01

    Recent measurements indicate significantly enhanced biogenic soil emissions of both nitric oxide (NO) and nitrous oxide (N2O) following surface burning. These enhanced fluxes persisted for at least six months following the burn. Simultaneous measurements indicate enhanced levels of exchangeable ammonium in the soil following the burn. Biomass burning is known to be an instantaneous source of NO and N2O resulting from high-temperature combustion. Now it is found that biomass burning also results in significantly enhanced biogenic emissions of these gases, which persist for months following the burn.

  11. Effect of natural Bayah zeolite particle size reduction to physico-chemical properties and absortion against potassium permanganate (KMnO4)

    NASA Astrophysics Data System (ADS)

    Widayanti, Siti Mariana; Syamsu, Khaswar; Warsiki, Endang; Yuliani, Sri

    2016-02-01

    Recently, researches on nanotechnology have been developed very rapid, as well as the utilization of nano-zeolites. Nano-sized material has several advantages which are expanding absorptive surfaces so it will enhance the material absorption and shorten the absorption time. Zeolite as a KMnO4 binder, has been widely recognized for its ability to extend the shelf life of vegetables and fruits. This study was conducted to determine zeolites physico-chemical characters from different particle size and the effect on KMnO4 absorption. Potassium permanganate (KMnO4) is a strong oxidizer for reducing the quantity of ethylene in storage process of fresh horticultural products. The treatment consisted of (1) different length of milling time (10, 20, 30, 40, and 60 minutes) and (2) the duration of chemical activation with 1 N KOH solution. Physical and chemical characters of zeolite were analyzed using BET, PSA, XRD and SEM. The research design was randomized design. The result implied that milling time was significantly affecting the zeolite particle size, material surface area, and the size of pore diameter and volume. Milling treatment for 40 minutes produced higher zeolite surface area and pore volume than other treatments. While the duration of chemical activation using 1 N KOH solution gives different effect on zeolite absorption to KMnO4 solution. Milling time for 60 minutes and activated for 48 hours has higher initial adsorption than other treatments.

  12. Enhanced Oxidation Catalysts for Water Reclamation

    NASA Technical Reports Server (NTRS)

    Jolly, Clifford D.

    1999-01-01

    This effort seeks to develop and test high-performance, long operating life, physically stable catalysts for use in spacecraft water reclamation systems. The primary goals are to a) reduce the quantity of expendable water filters used to purify water aboard spacecraft, b) to extend the life of the oxidation catalysts used for eliminating organic contaminants in the water reclamation systems, and c) reduce the weight/volume of the catalytic oxidation systems (e.g. VRA) used. This effort is targeted toward later space station utilization and will consist of developing flight-qualifiable catalysts and long-term ground tests of the catalyst prior to their utilization in flight. Fixed -bed catalytic reactors containing 5% platinum on granular activated carbon have been subjected to long-term dynamic column tests to measure catalyst stability vs throughput. The data generated so far indicate that an order of magnitude improvement can be obtained with the treated catalysts vs the control catalyst, at only a minor loss (approx 10%) in the initial catalytic activity.

  13. Oxidative challenge enhances REGγ-proteasome-dependent protein degradation.

    PubMed

    Zhang, Yuanyuan; Liu, Shuang; Zuo, Qiuhong; Wu, Lin; Ji, Lei; Zhai, Wanli; Xiao, Jianru; Chen, Jiwu; Li, Xiaotao

    2015-05-01

    Elimination of oxidized proteins is important to cells as accumulation of damaged proteins causes cellular dysfunction, disease, and aging. Abundant evidence shows that the 20S proteasome is largely responsible for degradation of oxidative proteins in both ubiquitin-dependent and ubiquitin-independent pathways. However, the role of the REGγ-proteasome in degrading oxidative proteins remains unclear. Here, we focus on two of the well-known REGγ-proteasome substrates, p21(Waf1/Cip1) and hepatitis C virus (HCV) core protein, to analyze the impact of oxidative stress on REGγ-proteasome functions. We demonstrate that REGγ-proteasome is essential for oxidative stress-induced rapid degradation of p21 and HCV proteins. Silencing REGγ abrogated this response in multiple cell lines. Furthermore, pretreatment with proteasome inhibitor MG132 completely blunted oxidant-induced p21 degradation, indicating a proteasome-dependent action. Cellular oxidation promoted REGγ-proteasome-dependent trypsin-like activity by enhancing the interaction between REGγ and 20S proteasome. Antioxidant could counteract oxidation-induced protein degradation, indicating that REGγ-proteasome activity may be regulated by redox state. This study provides further insights into the actions of a unique proteasome pathway in response to an oxidative stress environment, implying a novel molecular basis for REGγ-proteasome functions in antioxidation. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Enhanced disinfection efficiency of mechanically mixed oxidants with free chlorine.

    PubMed

    Son, Hyunju; Cho, Min; Kim, Jaeeun; Oh, Byungtaek; Chung, Hyenmi; Yoon, Jeyong

    2005-02-01

    To the best of our knowledge, this study is the first investigation to be performed into the potential benefits of mechanically mixed disinfectants in controlling bacterial inactivation. The purpose of this study was to evaluate the disinfection efficiency of mechanically mixed oxidants with identical oxidant concentrations, which were made by adding small amounts of subsidiary oxidants, namely ozone (O3), chlorine dioxide (ClO2), hydrogen peroxide (H2O2) and chlorite (ClO2(-)), to free available chlorine (Cl2), using Bacillus subtilis spores as the indicator microorganisms. The mechanically mixed oxidants containing Cl2/O3, Cl2/ClO2 and Cl2/ClO2(-) showed enhanced efficiencies (of up to 52%) in comparison with Cl2 alone, whereas no significant difference was observed between the mixed oxidant, Cl2/H2O2, and Cl2 alone. This enhanced disinfection efficiency can be explained by the synergistic effect of the mixed oxidant itself and the effect of intermediates such as ClO2(-)/ClO2, which are generated from the reaction between an excess of Cl2 and a small amount of O3/ClO2(-). Overall, this study suggests that mechanically mixed oxidants incorporating excess chlorine can constitute a new and moderately efficient method of disinfection.

  15. Anthropogenic iron oxide aerosols enhance atmospheric heating

    PubMed Central

    Moteki, Nobuhiro; Adachi, Kouji; Ohata, Sho; Yoshida, Atsushi; Harigaya, Tomoo; Koike, Makoto; Kondo, Yutaka

    2017-01-01

    Combustion-induced carbonaceous aerosols, particularly black carbon (BC) and brown carbon (BrC), have been largely considered as the only significant anthropogenic contributors to shortwave atmospheric heating. Natural iron oxide (FeOx) has been recognized as an important contributor, but the potential contribution of anthropogenic FeOx is unknown. In this study, we quantify the abundance of FeOx over East Asia through aircraft measurements using a modified single-particle soot photometer. The majority of airborne FeOx particles in the continental outflows are of anthropogenic origin in the form of aggregated magnetite nanoparticles. The shortwave absorbing powers (Pabs) attributable to FeOx and to BC are calculated on the basis of their size-resolved mass concentrations and the mean Pabs(FeOx)/Pabs(BC) ratio in the continental outflows is estimated to be at least 4–7%. We demonstrate that in addition to carbonaceous aerosols the aggregate of magnetite nanoparticles is a significant anthropogenic contributor to shortwave atmospheric heating. PMID:28508863

  16. Wet air oxidation induced enhanced biodegradability of distillery effluent.

    PubMed

    Malik, S N; Saratchandra, T; Tembhekar, P D; Padoley, K V; Mudliar, S L; Mudliar, S N

    2014-04-01

    The present study reports the feasibility of Wet Air Oxidation (WAO) as a pretreatment option for enhanced biodegradation of complex distillery effluent. Initially, the distillery effluent was pretreated by WAO at different process conditions (pressure, temperature and time) to facilitate enhancement in the biodegradability index (BI = BOD5: COD ratio). The biodegradability of WAO pretreated effluent was evaluated by subjecting it to aerobic biodegradation and anaerobic followed by aerobic biodegradation. Aerobic biodegradation of pretreated effluent with enhanced biodegradability index (BI = 0.4-0.8) showed enhanced COD reduction of up to 67.7%, whereas the untreated effluent (BI = 0.17) indicated poor COD reduction of only 22.5%. Anaerobic followed by aerobic biodegradation of pretreated effluent has shown up to 87.9% COD reduction, while the untreated effluent has shown only 43.1% COD reduction. Bio-kinetic parameters also confirmed the increased rate of bio-oxidation at enhanced BIs. The results indicate that the WAO pretreatment facilitates enhanced bio-oxidation/bio-degradation of complex effluents like the distillery spent wash.

  17. Enhanced oxidation resistance of active nanostructures via dynamic size effect

    PubMed Central

    Liu, Yun; Yang, Fan; Zhang, Yi; Xiao, Jianping; Yu, Liang; Liu, Qingfei; Ning, Yanxiao; Zhou, Zhiwen; Chen, Hao; Huang, Wugen; Liu, Ping; Bao, Xinhe

    2017-01-01

    A major challenge limiting the practical applications of nanomaterials is that the activities of nanostructures (NSs) increase with reduced size, often sacrificing their stability in the chemical environment. Under oxidative conditions, NSs with smaller sizes and higher defect densities are commonly expected to oxidize more easily, since high-concentration defects can facilitate oxidation by enhancing the reactivity with O2 and providing a fast channel for oxygen incorporation. Here, using FeO NSs as an example, we show to the contrary, that reducing the size of active NSs can drastically increase their oxidation resistance. A maximum oxidation resistance is found for FeO NSs with dimensions below 3.2 nm. Rather than being determined by the structure or electronic properties of active sites, the enhanced oxidation resistance originates from the size-dependent structural dynamics of FeO NSs in O2. We find this dynamic size effect to govern the chemical properties of active NSs. PMID:28223687

  18. Enhanced oxidation resistance of active nanostructures via dynamic size effect

    DOE PAGES

    Liu, Yun; Yang, Fan; Zhang, Yi; ...

    2017-02-22

    A major challenge limiting the practical applications of nanomaterials is that the activities of nanostructures (NSs) increase with reduced size, often sacrificing their stability in the chemical environment. Under oxidative conditions, NSs with smaller sizes and higher defect densities are commonly expected to oxidize more easily, since high-concentration defects can facilitate oxidation by enhancing the reactivity with O2 and providing a fast channel for oxygen incorporation. Here, using FeO NSs as an example, we show to the contrary, that reducing the size of active NSs can drastically increase their oxidation resistance. A maximum oxidation resistance is found for FeO NSsmore » with dimensions below 3.2 nm. Rather than being determined by the structure or electronic properties of active sites, the enhanced oxidation resistance originates from the size-dependent structural dynamics of FeO NSs in O2. We find this dynamic size effect to govern the chemical properties of active NSs.« less

  19. Fast and fully-scalable synthesis of reduced graphene oxide

    NASA Astrophysics Data System (ADS)

    Abdolhosseinzadeh, Sina; Asgharzadeh, Hamed; Seop Kim, Hyoung

    2015-05-01

    Exfoliation of graphite is a promising approach for large-scale production of graphene. Oxidation of graphite effectively facilitates the exfoliation process, yet necessitates several lengthy washing and reduction processes to convert the exfoliated graphite oxide (graphene oxide, GO) to reduced graphene oxide (RGO). Although filtration, centrifugation and dialysis have been frequently used in the washing stage, none of them is favorable for large-scale production. Here, we report the synthesis of RGO by sonication-assisted oxidation of graphite in a solution of potassium permanganate and concentrated sulfuric acid followed by reduction with ascorbic acid prior to any washing processes. GO loses its hydrophilicity during the reduction stage which facilitates the washing step and reduces the time required for production of RGO. Furthermore, simultaneous oxidation and exfoliation significantly enhance the yield of few-layer GO. We hope this one-pot and fully-scalable protocol paves the road toward out of lab applications of graphene.

  20. Fast and fully-scalable synthesis of reduced graphene oxide

    PubMed Central

    Abdolhosseinzadeh, Sina; Asgharzadeh, Hamed; Seop Kim, Hyoung

    2015-01-01

    Exfoliation of graphite is a promising approach for large-scale production of graphene. Oxidation of graphite effectively facilitates the exfoliation process, yet necessitates several lengthy washing and reduction processes to convert the exfoliated graphite oxide (graphene oxide, GO) to reduced graphene oxide (RGO). Although filtration, centrifugation and dialysis have been frequently used in the washing stage, none of them is favorable for large-scale production. Here, we report the synthesis of RGO by sonication-assisted oxidation of graphite in a solution of potassium permanganate and concentrated sulfuric acid followed by reduction with ascorbic acid prior to any washing processes. GO loses its hydrophilicity during the reduction stage which facilitates the washing step and reduces the time required for production of RGO. Furthermore, simultaneous oxidation and exfoliation significantly enhance the yield of few-layer GO. We hope this one-pot and fully-scalable protocol paves the road toward out of lab applications of graphene. PMID:25976732

  1. Rapid flow injection method for the determination of sulfite in wine using the permanganate-luminol luminescence system.

    PubMed

    Navarrro, Mercedes Villar; Payán, María Ramos; López, Miguel Angel Bello; Fernández-Torres, Rut; Mochón, Manuel Callejón

    2010-10-15

    A simple, rapid and sensitive chemiluminescence method for the determination of sulfite has been developed by combining flow-injection analysis and its sensitizing effect on the known chemiluminescence emission produced by the oxidation of luminol in alkaline medium; in this work permanganate has been proposed as oxidizing reactive. The optimum conditions for the chemiluminescence emission were established. The chemiluminescence was proportional to the sulfite concentration over the range 1.6 × 10(-5) and 4.0 × 10(-4)mol L(-1). The detection limit was 4.7 × 10(-6)mol L(-1) of sulfite. The method has been satisfactorily used for the determination of free and bound sulfite in wines.

  2. Significant enhancement of formic acid oxidation using rhodium nanostructures.

    PubMed

    Balan, Beena K; Sathe, Bhaskar R

    2012-12-01

    The electrocatalytic activity of as-synthesized shape selective Rh nanostructures has been demonstrated using cyclic voltammetry, revealing unique shape-dependant performance towards HCOOH oxidation. Interestingly, the enhancement factor (R) for different shapes of Rh with respect to that of commercial Rh towards formic acid oxidation ranges up to 20,000% for cubes as compared to 17,500% for pyramids and 11,000% for hexagons respectively. Mechanistic pathway for comparatively better sensitivity of cubes as compared to other shapes has been correlated with the results of X-ray diffraction.

  3. Enhancement of oxidative vaporization of chromium (III) oxide and chromium by oxygen atoms

    NASA Technical Reports Server (NTRS)

    Fryburg, G. C.; Kohl, F. J.; Stearns, C. A.

    1974-01-01

    Rates of oxidative vaporization of Cr2O3 were found to be markedly enhanced in the presence of O atoms. Investigations were conducted over the temperature range 470 to 1520 K. For Cr2O3 the enhancement was about 10 to the 9th power at 820 K in oxygen containing 2.5 percent atoms. Rapid oxidative vaporization of bare chromium was observed below 1070 K, the rate being about one-half that of Cr2O3. Results are interpreted in terms of thermochemical analysis.

  4. A Gallium Oxide-Graphene Oxide Hybrid Composite for Enhanced Photocatalytic Reaction

    PubMed Central

    Kim, Seungdu; Han, Kook In; Lee, In Gyu; Park, Won Kyu; Yoon, Yeojoon; Yoo, Chan Sei; Yang, Woo Seok; Hwang, Wan Sik

    2016-01-01

    Hybrid composites (HCs) made up of gallium oxide (GaO) and graphene oxide (GO) were investigated with the intent of enhancing a photocatalytic reaction under ultraviolet (UV) radiation. The material properties of both GaO and GO were preserved, even after the formation of the HCs. The incorporation of the GO into the GaO significantly enhanced the photocatalytic reaction, as indicated by the amount of methylene blue (MB) degradation. The improvements in the reaction were discussed in terms of increased surface area and the retarded recombination of generated charged carriers. PMID:28335255

  5. 21 CFR 250.108 - Potassium permanganate preparations as prescription drugs.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... crystals of potassium permanganate into the vagina. Experience with these cases shows that such use of... caustic, tissue-destroying chemical, and a poison. There are no circumstances under which crystals...

  6. Enhanced coal hydrogasification via oxidative pretreatment. Final technical report

    SciTech Connect

    Miller, D.J.

    1992-04-16

    The gasification of coal char by hydrogen is much slower than in steam or carbon dioxide; moreover, hydrogasification rate in pure hydrogen decreases sharply with conversion for most carbons. To overcome this kinetic behavior, the oxidation of the char prior to and during hydrogasification has been investigated as a means of enhancing hydro gasification rate. Kinetic rate studies under well-characterized conditions have been complemented by careful surface analyses to characterize oxygen on the char surface prior to and during hydrogasification.

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

    PubMed Central

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

    1995-01-01

    Recent studies have suggested that nitric oxide (NO.), the product of nitric oxide synthase in inflammatory cells, may play a part in tissue injury and inflammation through its oxidative metabolism. In this study the colonic generation of oxides of nitrogen (NOx) and nitric oxide synthase activity was determined in ulcerative colitis and Crohn's disease. Colonic biopsy specimens were obtained from inflammatory bowel disease patients and from normal controls. Mucosal explants were cultured in vitro for 24 hours and NOx generation was determined. Nitric oxide synthase activity was monitored by the conversion of [3H]-L-arginine to citrulline. Median NOx generation by inflamed colonic mucosa of patients with active ulcerative colitis and Crohn's colitis was 4.2- and 8.1-fold respectively higher than that by normal human colonic mucosa. In ulcerative colitis and Crohn's colitis nitric oxide synthase activity was 10.0- and 3.8-fold respectively higher than in normal subjects. Colonic NOx generation is significantly decreased by methylprednisolone and ketotifen. The decrease in NOx generation by cultured colonic mucosa induced by methylprednisolone suggests that NO synthase activity is induced during the culture and the steroid effect may contribute to its therapeutic effect. Enhanced colonic NOx generation by stimulated nitric oxide synthase activity in ulcerative colitis and Crohn's disease may contribute to tissue injury. PMID:7541008

  8. Enhanced ethanol electro-oxidation reaction on carbon supported Pd-metal oxide electrocatalysts.

    PubMed

    Abdel Hameed, R M

    2017-11-01

    Various Pd-metal oxide/C electrocatalysts were fabricated using ethylene glycol as a reducing agent in modified microwave-assisted polyol process. The crystal structure and surface morphology were studied using X-ray diffraction and transmission electron microscopy. All prepared Pd-metal oxide/C electrocatalysts exhibited a shift of Pd diffraction planes in the positive direction in relation to that of Pd/C. Highly dispersed palladium nanoparticles were formed on different metal oxide/C supports. The electrocatalytic performance of these electrocatalysts for ethanol oxidation was examined in NaOH solution using cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. An improvement in electrochemical parameters including onset potential, oxidation current density and If/Ib values was recorded at different Pd-metal oxide/C electrocatalysts, especially Pd-NiO/C. Three folds increment in steady state oxidation current density value was also displayed by investigated Pd-metal oxide/C electrocatalysts when contrasted to that of Pd/C to reflect their enhanced stability behavior. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Evaluation of ultrasound assisted potassium permanganate pre-treatment of spent coffee waste.

    PubMed

    Ravindran, Rajeev; Jaiswal, Swarna; Abu-Ghannam, Nissreen; Jaiswal, Amit K

    2017-01-01

    In the present study, novel pre-treatment for spent coffee waste (SCW) has been proposed which utilises the superior oxidising capacity of alkaline KMnO4 assisted by ultra-sonication. The pre-treatment was conducted for different exposure times (10, 20, 30 and 40min) using different concentrations of KMnO4 (1, 2, 3, 4, 5%w/v) at room temperature with solid/liquid ratio of 1:10. Pretreating SCW with 4% KMnO4 and exposing it to ultrasound for 20min resulted in 98% cellulose recovery and a maximum lignin removal of 46%. 1.7 fold increase in reducing sugar yield was obtained after enzymatic hydrolysis of KMnO4 pretreated SCW as compared to raw. SEM, XRD and FTIR analysis of the pretreated SCW revealed the various effects of pretreatment. Thermal behaviour of the pretreated substrate against the native biomass was also studied using DSC. Ultrasound-assisted potassium permanganate oxidation was found to be an effective pretreatment for SCW, and can be a used as a potential feedstock pretreatment strategy for bioethanol production. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Quantitation of Pyrantel Pamoate in Pharmaceuticals Using Permanganate by Visible Spectrophotometry

    NASA Astrophysics Data System (ADS)

    Rajendraprasad, N.; Basavaiah, K.

    2014-03-01

    Two simple, accurate and precise spectrophotometric methods are developed and validated for the assay of pyrantel pamoate (PP) in pharmaceuticals. The methods employ the oxidative property of potassium permanganate (KMnO4) in acidic and alkaline conditions. In the first method (method A), PP is converted into its free base, pyrantel (PR), and treated with known excess of KMnO4 in acidic condition followed by the measurement of unreacted KMnO4 at 550 nm. Method B is based on the registration of absorbance of green colored chromogen formed due to the reduction of KMnO4 by PP in alkaline condition. The methods obeyed Beer's law over a range of 1-20 μg/ml in inverse manner, and 0.75-15 μg/ml for method A and method B, respectively, with apparent molar absorptivity values of 1.05ṡ104 and 2.85ṡ104 lṡmol-1ṡcm-1. The optical parameters such as limits of detection (LOD), quantification (LOQ), and the Sandell sensitivity values are also reported. The accuracy and precision of the methods are assessed on intra- and inter-day basis. A recovery study by standard addition procedure is also carried out for further assurance of accuracy. The developed methods are successfully applied to determine PP in tablets. The results are more satisfactory as per current ICH guidelines.

  11. Determination of iodide using flow injection with acidic potassium permanganate chemiluminescence detection.

    PubMed

    Yaqoob, Mohammad; Atiq-ur-Rehman; Waseem, Amir; Nabi, Abdul

    2006-01-01

    A simple and rapid flow-injection method is described for the determination of iodide, based on potassium permanganate chemiluminescence detection via oxidation of formaldehyde in aqueous hydrochloric acid. The calibration graph was linear over the range 1.0-12 x 10(-6) mol/L (r2 = 0.9955) with relative standard deviations (n = 4) in the range 1.0-3.5%. The detection limit (3sigma) was 1.0 x 10(-7) mol/L, with sample throughput of 120/h. The effect of interfering cations [Ca(II), Mg(II), Ni(II), Fe(II), Fe(III) and Pb(II)] and anions (Cl-, SO4(2-), PO4(3-), NO3-, NO2-, F- and SO3(2-)) were studied. The method was applied to iodized salt samples and the results obtained in the range 0.03 +/- 0.005 - 0.10 +/- 0.006 mg I/g were in reasonable agreement with the amount labelled. The method was statistically compared with the results obtained by titration; no significant disagreement at 95% confidence was observed.

  12. Enhancement of field emission characteristics of carbon nanotubes on oxidation.

    PubMed

    Mathur, Ashish; Roy, Susanta Sinha; Ray, Sekhar Chandra; Hazra, Kiran Shankar; Hamilton, Jeremy; Dickinson, Calum; McLaughlin, James; Misra, Devi Shankar

    2011-08-01

    Vertically aligned multi-walled carbon nanotubes (CNTs) were grown on p-type silicon wafer using thermal chemical vapor deposition process and subsequently treated with oxygen plasma for oxidation. It was observed that the electron field emission (EFE) characteristics are enhanced. It showed that the turn-on electric field (E(TOE)) of CNTs decreased from 0.67 (untreated) to 0.26 V/microm (oxygen treated). Raman spectra showed that the numbers of defects are increased, which are generated by oxygen-treatment, and absorbed molecules on the CNTs are responsible for the enhancement of EFE. Scanning electron microscopy and Transmission electron microscopy images were used to identify the quality and physical changes of the nanotube morphology and surfaces; revealing the evidence of enhancement in the field emission properties after oxygen-plasma treatment.

  13. Enhanced Oxidative Stress Is Responsible for TRPV4-Induced Neurotoxicity.

    PubMed

    Hong, Zhiwen; Tian, Yujing; Yuan, Yibiao; Qi, Mengwen; Li, Yingchun; Du, Yimei; Chen, Lei; Chen, Ling

    2016-01-01

    Transient receptor potential vanilloid 4 (TRPV4) has been reported to be responsible for neuronal injury in pathological conditions. Excessive oxidative stress can lead to neuronal damage, and activation of TRPV4 increases the production of reactive oxygen species (ROS) and nitric oxide (NO) in many types of cells. The present study explored whether TRPV4-induced neuronal injury is mediated through enhancing oxidative stress. We found that intracerebroventricular injection of the TRPV4 agonist GSK1016790A increased the content of methane dicarboxylic aldehyde (MDA) and NO in the hippocampus, which was blocked by administration of the TRPV4 specific antagonist HC-067047. The activities of catalase (CAT) and glutathione peroxidase (GSH-Px) were decreased by GSK1016790A, whereas the activity of superoxide dismutase (SOD) remained unchanged. Moreover, the protein level and activity of neuronal nitric oxide synthase (nNOS) were increased by GSK1016790A, and the GSK1016790A-induced increase in NO content was blocked by an nNOS specific antagonist ARL-17477. The GSK1016790A-induced modulations of CAT, GSH-Px and nNOS activities and the protein level of nNOS were significantly inhibited by HC-067047. Finally, GSK1016790A-induced neuronal death and apoptosis in the hippocampal CA1 area were markedly attenuated by administration of a ROS scavenger Trolox or ARL-17477. We conclude that activation of TRPV4 enhances oxidative stress by inhibiting CAT and GSH-Px and increasing nNOS, which is responsible, at least in part, for TRPV4-induced neurotoxicity.

  14. Novel concept of functional oxide coatings providing enhanced oxidation resistance to Ni-based superalloys

    SciTech Connect

    Pedraza, F. Balmain, J. Bonnet, G. Bouchaud, B.

    2014-01-01

    Graphical abstract: - Highlights: • New concept for providing extended oxidation resistance to Ni-based superalloys. • Oxygen-defective nanostructured oxide coatings reduce the oxygen partial pressure at the substrate interface. • Pre-oxidation of the substrate during annealing with the formation of alpha-alumina. • Growth of CeAlO{sub 3} perovskite enhancing the adherence of the ceria top coat. • Microstructural stability of the coating system with no SRZ formation upon exposure. - Abstract: Aluminide-coated Ni-based superalloys are prone to microstructural instabilities during long-term exposure at high temperature with the growth of a secondary reaction zone (SRZ) detrimental from a mechanical viewpoint. This has been since overcome by the use of thermodynamically stable coatings (γ-Ni/γ′-Ni{sub 3}Al). However, additions of Pt and Hf are required to provide the formation of an exclusive α-Al{sub 2}O{sub 3} scale and improved oxidation resistance in cyclic and isothermal regimes. The present work proposes a new coating system that relies on the use of a superficial nanostructured functional oxide providing the establishment of a stable alumina while avoiding SRZ formation. Tailored oxygen-defective and multi-cracked coatings were designed for 2nd generation Ni-based superalloys and generated by electrosynthesis using a water-based solution. Cyclic oxidation tests were carried out at 1100 °C in air and the oxidation properties and the microstructural stability of the coating system were demonstrated.

  15. Solvent free hydroxylation of the methyl esters of Blighia unijugata seed oil in the presence of cetyltrimethylammonium permanganate

    PubMed Central

    2011-01-01

    Extraction of oil from the seed of Blighia unijugata gave a yield of 50.82 ± 1.20% using hexane in a soxhlet extractor. The iodine and saponification values were 67.60 ± 0.80 g iodine/100 g and 239.20 ± 1.00 mg KOH/g respectively with C18:1 being the dominant fatty acid. Unsaturated methyl esters of Blighia unijugata which had been previously subjected to urea adduct complexation was used to synthesize methyl 9, 10-dihydroxyoctadecanoate via hydroxylation in the presence of cetyltrimethylammonium permanganate (CTAP). The reaction was monitored and confirmed using FTIR and GC-MS. This study has revealed that oxidation reaction of mono unsaturated bonds using CTAP could be achieved under solvent free condition. PMID:22145711

  16. Transformation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) by permanganate.

    PubMed

    Chokejaroenrat, Chanat; Comfort, Steve D; Harris, Clifford E; Snow, Daniel D; Cassada, David; Sakulthaew, Chainarong; Satapanajaru, Tunlawit

    2011-04-15

    The chemical oxidant permanganate (MnO(4)(-)) has been shown to effectively transform hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) at both the laboratory and field scales. We treated RDX with MnO(4)(-) with the objective of quantifying the effects of pH and temperature on destruction kinetics and determining reaction rates. A nitrogen mass balance and the distribution of reaction products were used to provide insight into reaction mechanisms. Kinetic experiments (at pH ∼ 7, 25 °C) verified that RDX-MnO(4)(-) reaction was first-order with respect to MnO(4)(-) and initial RDX concentration (second-order rate: 4.2 × 10(-5) M(-1) s(-1)). Batch experiments showed that choice of quenching agents (MnSO(4), MnCO(3), and H(2)O(2)) influenced sample pH and product distribution. When MnCO(3) was used as a quenching agent, the pH of the RDX-MnO(4)(-) solution was relatively unchanged and N(2)O and NO(3)(-) constituted 94% of the N-containing products after 80% of the RDX was transformed. On the basis of the preponderance of N(2)O produced under neutral pH (molar ratio N(2)O/NO(3) ∼ 5:1), no strong pH effect on RDX-MnO(4)(-) reaction rates, a lower activation energy than the hydrolysis pathway, and previous literature on MnO(4)(-) oxidation of amines, we propose that RDX-MnO(4)(-) reaction involves direct oxidation of the methylene group (hydride abstraction), followed by hydrolysis of the resulting imides, and decarboxylation of the resulting carboxylic acids to form N(2)O, CO(2), and H(2)O.

  17. Enhanced arsenite removal through surface-catalyzed oxidative coagulation treatment.

    PubMed

    Li, Yue; Bland, Garret D; Yan, Weile

    2016-05-01

    Arsenic being a naturally-occurring groundwater contaminant is subject to stringent water quality regulations. Coagulation and adsorption are widely used methods to treat arsenic-contaminated water, however, these treatments have been reported to be less efficient for the removal of arsenite (As(III)) than arsenate (As(V)). In this study, the feasibility of in situ oxidation of As(III) during coagulation was investigated in two systems: Fe(II) or H2O2-assisted oxidative coagulation treatment using ferric chloride as the coagulant. This setup exploits the catalytic property of the fresh formed Fe(III) hydroxide colloids in coagulation suspension to mediate the production of reactive oxidants capable of As(III) oxidation. Fe(II)-assisted coagulation brought about small improvements in As(III) removal compared to treatment with Fe(III) coagulant alone, however, its arsenic removal efficiency is strongly dependent on pH (observed optimal pH = 7-9). Addition of H2O2 together with ferric chloride led to a significant enhancement in arsenic retention at pH 6-8, with final arsenic concentrations well below the U.S.EPA regulatory limit (10 μg/L). H2O2-assisted oxidative coagulation can attain reliable As(III) removal over a broad pH range of 4-9. Radical quenching experiments reveal the participation of superoxide radical in As(III) removal in the oxidative coagulation systems. Phosphate (at > 0.1 mM) strongly suppresses As(III) removal efficiency, whereas carbonate and humic acid pose a minor impact. Overall, the results suggest that a low dose addition of H2O2 along with ferric coagulant is a feasible method for the existing water treatment facilities to achieve improved As(III) removal efficiency. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Rapid Microwave Synthesis of Perovskite Oxide Nanostructures with Enhanced Functionality

    NASA Astrophysics Data System (ADS)

    Salazar, Gregory; Datta, Anuja; Mukherjee, Pritish

    2015-03-01

    Perovskite oxides are an important class of materials having high dielectric and piezoelectric coefficients, switchable ferroelectric (FE) polarization and interesting optical and electrical properties. Realization of functional devices based on classic perovskite oxides such as Pb(Zr0.52Ti0.48) O3 (PZT), and emerging Pb-free noncentrosymmetric (NCS) oxides, such as, ZnSnO3, ZnTiO3 and CaTiO3 have reinforced the investigation of these materials in multiple dimensions and length scales. However, large-scale synthesis and integration of ordered low-dimensional structures is a challenge, due to their complicated methodologies, high-cost and difficulties with phase stability. We discuss a generalized, cost-effective, rapid microwave synthesis route for size and shape selective nanostructure growth of these functional perovskite oxides on industrially viable flexible and hard substrates, stabilized by an enhanced ionic covalence. The rational synthesis approach allowed improved tunability of the size, shape, and orientation of the structures with improved electrical and FE properties. The facile fabrication route of these nanostructures may expand the outreach of probes for understanding the structure-property relationships in these hitherto unexplored and technologically important materials.

  19. One-step sonochemical synthesis of a graphene oxide-manganese oxide nanocomposite for catalytic glycolysis of poly(ethylene terephthalate)

    NASA Astrophysics Data System (ADS)

    Park, Gle; Bartolome, Leian; Lee, Kyoung G.; Lee, Seok Jae; Kim, Do Hyun; Park, Tae Jung

    2012-06-01

    Ultrasound-assisted synthesis of a graphene oxide (GO)-manganese oxide nanocomposite (GO-Mn3O4) was conducted without further modification of GO or employing secondary materials. With the GO nanoplate as a support, potassium permanganate oxidizes the carbon atoms in the GO support and gets reduced to Mn3O4. An intensive ultrasound method could reduce the number of reaction steps and temperature, enhance the reaction rate and furthermore achieve a Mn3O4 phase. The composite was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The coverage and crystallinity of Mn3O4 were controlled by changing the ratio of permanganate to GO dispersion. The synthesized nanocomposite was used as a catalyst for poly(ethylene terephthalate) (PET) depolymerization into its monomer, bis(2-hydroxylethyl) terephthalate (BHET). The highest monomer yield of 96.4% was obtained with the nanocomposite containing the lowest amount of Mn3O4, while PET glycolysis with the Mn3O4 without GO yielded 82.7% BHET.Ultrasound-assisted synthesis of a graphene oxide (GO)-manganese oxide nanocomposite (GO-Mn3O4) was conducted without further modification of GO or employing secondary materials. With the GO nanoplate as a support, potassium permanganate oxidizes the carbon atoms in the GO support and gets reduced to Mn3O4. An intensive ultrasound method could reduce the number of reaction steps and temperature, enhance the reaction rate and furthermore achieve a Mn3O4 phase. The composite was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The coverage and crystallinity of Mn3O4 were controlled by changing the ratio of permanganate to GO dispersion. The synthesized nanocomposite was used as a catalyst for poly

  20. Comparison of enhanced device response and predicted x-ray dose enhancement effects on MOS oxides

    SciTech Connect

    Fleetwood, D.M.; Beutler, D.E.; Lorence, L.J. Jr.; Draper, B.L.; Brown, D.B.; Riewe, L.C.; Rosenstock, H.B.; Knott, D.P.

    1988-12-01

    The response of MOS capacitors to low- and medium-energy x-ray irradiation is investigated as a function of gate material (TaSi or Al), oxide thickness, and electric field. Measured device response is compared with predictions based on discrete ordinates and Monte Carlo code simulations of dose enhancement effects, coupled with recent estimates of electron-hole recombination in MOS oxides. In comparisons of 10-keV x-ray and Co-60 irradiations of Al-gate MOS capacitors at an oxide electric field of 1 MV/cm, it is found that predictions and experiments agree to within better than 20 percent for oxide thicknesses ranging from 35 to 1060 nm. For capacitors having TaSi/Al gates, predictions and experiments agree to within better than 30 percent at 1 MV/cm, with the largest differences occurring for 35-nm gate oxides. At other electric fields, the disagreement between experiment and prediction increases significantly for both Al- and TaSi/Al-gate capacitors, and can be greater than a factor of 2 at applied electric fields below 0.1 MV/cm. For medium energy (-- 100 keV average photon energy) x-ray irradiations, the enhanced device response exhibits a much stronger dependence on endpoint bremsstrahlung energy than expected from TIGERP or CEPXS/ONETRAN simulations. Implications for hardness assurance testing are discussed.

  1. Enhancing CO2 electroreduction with the metal–oxide interface

    DOE PAGES

    Gao, Dunfeng; Zhang, Yi; Zhou, Zhiwen; ...

    2017-04-09

    Here, the electrochemical CO2 reduction reaction (CO2RR) typically uses transition metals as the catalysts. To improve the efficiency, tremendous efforts have been dedicated to tuning the morphology, size, and structure of metal catalysts and employing electrolytes that enhance the adsorption of CO2. We report here a strategy to enhance CO2RR by constructing the metal–oxide interface. We demonstrate that Au–CeOx shows much higher activity and Faradaic efficiency than Au or CeOx alone for CO2RR. In situ scanning tunneling microscopy and synchrotron-radiation photoemission spectroscopy show that the Au–CeOx interface is dominant in enhancing CO2 adsorption and activation, which can be further promotedmore » by the presence of hydroxyl groups. Density functional theory calculations indicate that the Au–CeOx interface is the active site for CO2 activation and the reduction to CO, where the synergy between Au and CeOx promotes the stability of key carboxyl intermediate (*COOH) and thus facilitates CO2RR. Similar interface-enhanced CO2RR is further observed on Ag–CeOx, demonstrating the generality of the strategy for enhancing CO2RR.« less

  2. A five-year performance review of field-scale, slow-release permanganate candles with recommendations for second-generation improvements

    PubMed Central

    Christenson, Mark; Kambhu, Ann; Reece, James; Comfort, Steve; Brunner, Laurie

    2016-01-01

    In 2009, we identified a TCE plume at an abandoned landfill that was located in a low permeable silty-clay aquifer. To treat the TCE, we manufactured slow-release potassium permanganate cylinders (oxidant candles) that had diameters of either 5.1 or 7.6 cm and were 91.4 cm long. In 2010, we compared two methods of candle installation by inserting equal masses of the oxidant candles (7.6-cm vs 5.1-cm dia). The 5.1-cm dia candles were inserted with direct-push rods while the 7.6-cm candles were housed in screens and lowered into 10 permanent wells. Since installation, the 7.6-cm oxidant candles have been refurbished approximately once per year by gently scraping off surface oxides. In 2012, we reported initial results; in this paper, we provide a 5-yr performance review since installation. Temporal sampling shows oxidant candles placed in wells have steadily reduced migrating TCE concentrations. Moreover, these candles still maintain an inner core of oxidant that has yet to contribute to the dissolution front and should provide several more years of service. Oxidant candles inserted by direct-push have stopped reducing TCE concentrations because a MnO2 scale developed on the outside of the candles. To counteract oxide scaling, we fabricated a second generation of oxidant candles that contain sodium hexametaphosphate. Laboratory experiments (batch and flow-through) show that these second-generation permanganate candles have better release characteristics and are less prone to oxide scaling. This improvement should reduce the need to perform maintenance on candles placed in wells and provide greater longevity for candles inserted by direct-push. PMID:26901481

  3. A five-year performance review of field-scale, slow-release permanganate candles with recommendations for second-generation improvements.

    PubMed

    Christenson, Mark; Kambhu, Ann; Reece, James; Comfort, Steve; Brunner, Laurie

    2016-05-01

    In 2009, we identified a TCE plume at an abandoned landfill that was located in a low permeable silty-clay aquifer. To treat the TCE, we manufactured slow-release potassium permanganate cylinders (oxidant candles) that had diameters of either 5.1 or 7.6 cm and were 91.4 cm long. In 2010, we compared two methods of candle installation by inserting equal masses of the oxidant candles (7.6-cm vs 5.1-cm dia). The 5.1-cm dia candles were inserted with direct-push rods while the 7.6-cm candles were housed in screens and lowered into 10 permanent wells. Since installation, the 7.6-cm oxidant candles have been refurbished approximately once per year by gently scraping off surface oxides. In 2012, we reported initial results; in this paper, we provide a 5-yr performance review since installation. Temporal sampling shows oxidant candles placed in wells have steadily reduced migrating TCE concentrations. Moreover, these candles still maintain an inner core of oxidant that has yet to contribute to the dissolution front and should provide several more years of service. Oxidant candles inserted by direct-push have stopped reducing TCE concentrations because a MnO2 scale developed on the outside of the candles. To counteract oxide scaling, we fabricated a second generation of oxidant candles that contain sodium hexametaphosphate. Laboratory experiments (batch and flow-through) show that these second-generation permanganate candles have better release characteristics and are less prone to oxide scaling. This improvement should reduce the need to perform maintenance on candles placed in wells and provide greater longevity for candles inserted by direct-push. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Enhanced formic acid oxidation on Cu-Pd nanoparticles

    NASA Astrophysics Data System (ADS)

    Dai, Lin; Zou, Shouzhong

    Developing catalysts with high activity and high resistance to surface poisoning remains a challenge in direct formic acid fuel cell research. In this work, copper-palladium nanoparticles were formed through a galvanic replacement process. After electrochemically selective dissolution of surface Cu, Pd-enriched Cu-Pd nanoparticles were formed. These particles exhibit much higher formic acid oxidation activities than that on pure Pd nanoparticles, and they are much more resistant to the surface poisoning. Possible mechanisms of catalytic activity enhancement are briefly discussed.

  5. High-resolution experiments on chemical oxidation of DNAPL in variable-aperture fractures

    NASA Astrophysics Data System (ADS)

    Arshadi, Masoud; Rajaram, Harihar; Detwiler, Russell L.; Jones, Trevor

    2015-04-01

    Chemical oxidation of dense nonaqueous-phase liquids (DNAPLs) by permanganate has emerged as an effective remediation strategy in fractured rock. We present high-resolution experimental investigations in transparent analog variable-aperture fractures to improve understanding of chemical oxidation of residual entrapped trichloroethylene (TCE) in fractures. Four experiments were performed with different permanganate concentrations, flow rates, and initial TCE phase geometry. The initial aperture field and evolving entrapped-phase geometry were quantified for each experiment. The integrated mass transfer rate from the TCE phase for all experiments exhibited three time regimes: an early-time regime with slower mass transfer rates limited by low specific interfacial area; an intermediate-time regime with higher mass transfer rates resulting from breakup of large TCE blobs, which greatly increases specific interfacial area; and a late-time regime with low mass transfer rates due to the deposition of MnO2 precipitates. In two experiments, mass balance analyses suggested that TCE mass removal rates exceeded the maximum upper bound mass removal rates derived by assuming that oxidation and dissolution are the only mechanisms for TCE mass removal. We propose incomplete oxidation by permanganate and TCE solubility enhancement by intermediate reaction products as potential mechanisms to explain this behavior. We also speculate that some intermediate reaction products with surfactant-like properties may play a role in lowering the TCE-water interfacial tension, thus causing breakup of large TCE blobs. Our quantitative experimental measurements will be useful in the context of developing accurate computational models for chemical oxidation of TCE in fractures.

  6. Annealing and oxidation of silicon oxide films prepared by plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Chen, X. Y.; Lu, Y. F.; Tang, L. J.; Wu, Y. H.; Cho, B. J.; Xu, X. J.; Dong, J. R.; Song, W. D.

    2005-01-01

    We have investigated phase separation, silicon nanocrystal (Si NC) formation and optical properties of Si oxide (SiOx, 0oxidation. The SiOx films were deposited by plasma-enhanced chemical vapor deposition at different nitrous-oxide/silane flow ratios. The physical and optical properties of the SiOx films were studied as a result of high-vacuum annealing and thermal oxidation. X-ray photoelectron spectroscopy (XPS) reveals that the as-deposited films have a random-bonding or continuous-random-network structure with different oxidation states. After annealing at temperatures above 1000 °C, the intermediate Si continuum in XPS spectra (referring to the suboxide) split to Si peaks corresponding to SiO2 and elemental Si. This change indicates the phase separation of the SiOx into more stable SiO2 and Si clusters. Raman, high-resolution transmission electron microscopy and optical absorption confirmed the phase separation and the formation of Si NCs in the films. The size of Si NCs increases with increasing Si concentration in the films and increasing annealing temperature. Two photoluminescence (PL) bands were observed in the films after annealing. The ultraviolet (UV)-range PL with a peak fixed at 370-380 nm is independent of Si concentration and annealing temperature, which is a characteristic of defect states. Strong PL in red range shows redshifts from ˜600 to 900 nm with increasing Si concentration and annealing temperature, which supports the quantum confinement model. After oxidation of the high-temperature annealed films, the UV PL was almost quenched while the red PL shows continuous blueshifts with increasing oxidation time. The different oxidation behaviors further relate the UV PL to the defect states and the red PL to the recombination of quantum-confined excitions.

  7. Defect induced mobility enhancement: Gadolinium oxide (100) on Si(100)

    SciTech Connect

    Sitaputra, W.; Tsu, R.

    2012-11-26

    Growth of predominantly single crystal (100)-oriented gadolinium oxide (Gd{sub 2}O{sub 3}) on a p-type Si(100) and growth of a polycrystal with a predominant Gd{sub 2}O{sub 3}(100) crystallite on a n-type Si(100) was performed using molecular beam epitaxy. Despite a poorer crystal structure than Gd{sub 2}O{sub 3}(110), an enhancement in carrier mobility can be found only from the Gd{sub 2}O{sub 3}(100)/n-type Si(100) interface. The mobility of 1715-1780 cm{sup 2}/V {center_dot} s was observed at room temperature, for carrier concentration >10{sup 20} cm{sup -3}. This accumulation of the electrons and the mobility enhancement may arise from the two-dimensional confinement due to charge transfer across the interface similar to transfer doping.

  8. Emission control system for nitrogen oxides using enhanced oxidation, scrubbing, and biofiltration

    SciTech Connect

    Martinez, A.; Cabezas, J.

    2009-05-15

    Nitric oxide (NO) constitutes about 90% of the nitrogen oxide (NOx) species in the flue gases emitted from combustion processes, but NO is difficult to remove in existing scrubbers due to its low solubility. NO may be oxidized with hydrogen peroxide (H{sub 2}O{sub 2}) into soluble species that can be partially removed in wet scrubbers simultaneously with sulfur dioxide (SO{sub 2}) and biofilters located downstream of the scrubber can increase the removal efficiency. This article presents the results of a bench-scale evaluation of such an integrated system combining enhanced oxidation, scrubbing, and biofiltration. Main components of the bench-scale system consisted of a quartz tube in a furnace to simulate the NO oxidation stage and two vertical packed bed cylinders constituting the scrubber and the biofilter. Inlet synthetic gas had a concentration of 50 mu L/L of NO. Overall removal efficiency by the integrated system was in the range of 53% to 93% with an average of 79%, absorption accounted for 43% and biofiltration for 36% of the total removal. Key parameters in the operation of the system are the H{sub 2}O{sub 2}:NO mole ratio, the reaction temperature, the liquid to gas flow ratio, and the biofilter residence time. Experimental results suggest a path for optimization of the technology focusing simultaneously in minimizing H{sub 2}O{sub 2} use in the enhanced oxidation stage, reducing water consumption in the scrubber stage and balancing the residence times in the three stages of the integrated system.

  9. Field demonstration of polymer-amended in situ chemical oxidation (PA-ISCO)

    NASA Astrophysics Data System (ADS)

    Silva, Jeff A. K.; Crimi, Michelle; Palaia, Thomas; Ko, Saebom; Davenport, Sean

    2017-04-01

    The methods and results of the first field-scale demonstration of polymer-amended in situ chemical oxidation (PA-ISCO) are presented. The demonstration took place at MCB CAMLEJ (Marine Corps Base, Camp Lejeune) Operable Unit (OU) 15, Site 88, in Camp Lejeune, North Carolina between October and December 2010. PA-ISCO was developed as an alternative treatment approach that utilizes viscosity-modified fluids to improve the in situ delivery and distribution (i.e. sweep-efficiency) of chemical oxidants within texturally heterogeneous contaminated aquifers. The enhanced viscosity of the fluid mitigates the effects of preferential flows, improving sweep-efficiency and enhancing the subsurface contact between the injected oxidant and the target contamination within the treatment zone. The PA-ISCO fluid formulation used in this demonstration included sodium permanganate as oxidant, xanthan gum biopolymer as a shear-thinning viscosifier, and sodium hexametaphosphate (SHMP) as an anti-coagulant. It was the goal of this demonstration to validate the utility of PA-ISCO within a heterogeneous aquifer. An approximate 100% improvement in sweep-efficiency was achieved for the PA-ISCO fluid, as compared to a permanganate-only injection within an adjacent control plot.

  10. Field demonstration of polymer-amended in situ chemical oxidation (PA-ISCO).

    PubMed

    Silva, Jeff A K; Crimi, Michelle; Palaia, Thomas; Ko, Saebom; Davenport, Sean

    2017-04-01

    The methods and results of the first field-scale demonstration of polymer-amended in situ chemical oxidation (PA-ISCO) are presented. The demonstration took place at MCB CAMLEJ (Marine Corps Base, Camp Lejeune) Operable Unit (OU) 15, Site 88, in Camp Lejeune, North Carolina between October and December 2010. PA-ISCO was developed as an alternative treatment approach that utilizes viscosity-modified fluids to improve the in situ delivery and distribution (i.e. sweep-efficiency) of chemical oxidants within texturally heterogeneous contaminated aquifers. The enhanced viscosity of the fluid mitigates the effects of preferential flows, improving sweep-efficiency and enhancing the subsurface contact between the injected oxidant and the target contamination within the treatment zone. The PA-ISCO fluid formulation used in this demonstration included sodium permanganate as oxidant, xanthan gum biopolymer as a shear-thinning viscosifier, and sodium hexametaphosphate (SHMP) as an anti-coagulant. It was the goal of this demonstration to validate the utility of PA-ISCO within a heterogeneous aquifer. An approximate 100% improvement in sweep-efficiency was achieved for the PA-ISCO fluid, as compared to a permanganate-only injection within an adjacent control plot. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Monoclinic Tungsten Oxide with {100} Facet Orientation and Tuned Electronic Band Structure for Enhanced Photocatalytic Oxidations.

    PubMed

    Zhang, Ning; Chen, Chen; Mei, Zongwei; Liu, Xiaohe; Qu, Xiaolei; Li, Yunxiang; Li, Siqi; Qi, Weihong; Zhang, Yuanjian; Ye, Jinhua; Roy, Vellaisamy A L; Ma, Renzhi

    2016-04-27

    Exploring surface-exposed highly active crystal facets for photocatalytic oxidations is promising in utilizing monoclinic WO3 semiconductor. However, the previously reported highly active facets for monoclinic WO3 were mainly toward enhancing photocatalytic reductions. Here we report that the WO3 with {100} facet orientation and tuned surface electronic band structure can effectively enhance photocatalytic oxidation properties. The {100} faceted WO3 single crystals are synthesized via a facile hydrothermal method. The UV-visible diffuse reflectance, X-ray photoelectron spectroscopy valence band spectra, and photoelectrochemical measurements suggest that the {100} faceted WO3 has a much higher energy level of valence band maximum compared with the normal WO3 crystals without preferred orientation of the crystal face. The density functional theory calculations reveal that the shift of O 2p and W 5d states in {100} face induce a unique band structure. In comparison with the normal WO3, the {100} faceted WO3 exhibits an O2 evolution rate about 5.1 times in water splitting, and also shows an acetone evolution rate of 4.2 times as well as CO2 evolution rate of 3.8 times in gaseous degradation of 2-propanol. This study demonstrates an efficient crystal face engineering route to tune the surface electronic band structure for enhanced photocatalytic oxidations.

  12. Understanding Interactions between Manganese Oxide and Gold That Lead to Enhanced Activity for Electrocatalytic Water Oxidation

    PubMed Central

    2015-01-01

    To develop active nonprecious metal-based electrocatalysts for the oxygen evolution reaction (OER), a limiting reaction in several emerging renewable energy technologies, a deeper understanding of the activity of the first row transition metal oxides is needed. Previous studies of these catalysts have reported conflicting results on the influence of noble metal supports on the OER activity of the transition metal oxides. Our study aims to clarify the interactions between a transition metal oxide catalyst and its metal support in turning over this reaction. To achieve this goal, we examine a catalytic system comprising nanoparticulate Au, a common electrocatalytic support, and nanoparticulate MnOx, a promising OER catalyst. We conclusively demonstrate that adding Au to MnOx significantly enhances OER activity relative to MnOx in the absence of Au, producing an order of magnitude higher turnover frequency (TOF) than the TOF of the best pure MnOx catalysts reported to date. We also provide evidence that it is a local rather than bulk interaction between Au and MnOx that leads to the observed enhancement in the OER activity. Engineering improvements in nonprecious metal-based catalysts by the addition of Au or other noble metals could still represent a scalable catalyst as even trace amounts of Au are shown to lead a significant enhancement in the OER activity of MnOx. PMID:24661269

  13. Sewage sludge treatment using microwave-enhanced advanced oxidation process.

    PubMed

    Yin, Gui Q; Liao, Ping H; Lo, Kwang V

    2008-02-01

    A microwave-enhanced advanced oxidation process using hydrogen peroxide (MW/H(2)O(2)-AOP) was used for the release of nutrients and the destruction of solids from secondary municipal sewage sludge in this study. Using a computer statistical software package for designing experiments and for data analyses, four factors including microwave heating temperature, heating time, hydrogen peroxide dosage, and sludge solids content were examined. Experiments were performed at sludge solids content of 0.5, 1.5 and 2.5%, heating temperature of 80, 100 and 120 degrees C, heating time of 1.5, 3 and 9 minutes, and hydrogen peroxide dosage of 0, 1 and 2 wt %, respectively. Overall, the maximum solubilization of nutrients was obtained at 2.5% of total solids content, 2 wt % of hydrogen peroxide, 5 min. of microwave heating and at 120 degrees C. The most significant factor for the solubilization of nutrients using the microwave enhanced advanced oxidation process was the initial sludge concentration. Hydrogen peroxide dosage was also a very significant factor. The maximum yield occurred at an extended heating period of five minutes in this study. Nevertheless, the results indicated that the nutrient release and disintegration of solids were also very substantial over heating periods of 1.5 and 3 minutes. Even with a heating period of 1.5 minutes, the yield was estimated to be about 70% that of the 5 minute heating.

  14. Nanosized Iron Oxide Colloids Strongly Enhance Microbial Iron Reduction▿ †

    PubMed Central

    Bosch, Julian; Heister, Katja; Hofmann, Thilo; Meckenstock, Rainer U.

    2010-01-01

    Microbial iron reduction is considered to be a significant subsurface process. The rate-limiting bioavailability of the insoluble iron oxyhydroxides, however, is a topic for debate. Surface area and mineral structure are recognized as crucial parameters for microbial reduction rates of bulk, macroaggregate iron minerals. However, a significant fraction of iron oxide minerals in the subsurface is supposed to be present as nanosized colloids. We therefore studied the role of colloidal iron oxides in microbial iron reduction. In batch growth experiments with Geobacter sulfurreducens, colloids of ferrihydrite (hydrodynamic diameter, 336 nm), hematite (123 nm), goethite (157 nm), and akaganeite (64 nm) were added as electron acceptors. The colloidal iron oxides were reduced up to 2 orders of magnitude more rapidly (up to 1,255 pmol h−1 cell−1) than bulk macroaggregates of the same iron phases (6 to 70 pmol h−1 cell−1). The increased reactivity was not only due to the large surface areas of the colloidal aggregates but also was due to a higher reactivity per unit surface. We hypothesize that this can be attributed to the high bioavailability of the nanosized aggregates and their colloidal suspension. Furthermore, a strong enhancement of reduction rates of bulk ferrihydrite was observed when nanosized ferrihydrite aggregates were added. PMID:19915036

  15. Can H2 enhance the oxidative dissolution of UO2?

    NASA Astrophysics Data System (ADS)

    Barreiro Fidalgo, Alexandre; Jonsson, Mats

    2016-08-01

    Understanding the mechanism and kinetics of spent nuclear fuel dissolution in water is of key-importance for the safety assessment of deep geological repositories for spent nuclear fuel [1-5]. For UO2-based fuel, radiation induced oxidative dissolution of the fuel matrix is of considerable importance as this will enhance the release of fission products and actinides by several orders of magnitude [2-4]. This process has been studied extensively over several decades and can now be considered to be fairly well understood [2-6]. The aqueous radiolysis product identified as mainly being responsible for the oxidative dissolution of UO2 is H2O2[7]. In addition to oxidation of U(IV) to U(VI), H2O2 also undergoes catalytic decomposition on the UO2-surface [8,9]. In fact, it has been shown that catalytic decomposition is the major route on UO2-pellets [10,11]. In recent years it has been shown that this process involves the formation of surface bound hydroxyl radicals [12]. The mechanism of the catalytic decomposition is depicted in reaction (1-3).

  16. Arginine-Containing Ligands Enhance H-2 Oxidation Catalyst Performance

    SciTech Connect

    Dutta, Arnab; Roberts, John A.; Shaw, Wendy J.

    2014-06-16

    In H2 fuel cells, performance depends on factors controlling turnover frequency and energy efficiency in the electrocatalytic oxidation of H2. Nature uses the hydrogenase enzymes to oxidize H2 at high turnover frequencies (up to 20,000 s-1) and low overpotentials (<100 mV), while the fastest synthetic catalyst reported to date only oxidizes H2 at 50 s-1 under 1 atm H2. Here we report a water-soluble complex incorporating the amino acid arginine, [NiII(PCy2NArg2)2]6+, that operates at 210 s-1 (180 mV overpotential) under 1 atm H2 and 144,000 s-1 (460 mV overpotential) under 133 atm H2. The complex functions from pH 0-14 with rates increasing at lower pH values. The arginine groups impart water solubility and play a critical role in enhancing turnover frequency, most consistent with an intramolecular Arg-Arg interaction that controls the structure of the catalyst active site. This work was funded by the Office of Science Early Career Research Program through the US DOE, BES (AD, WJS), and the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US DOE, BES (JASR). PNNL is operated by Battelle for the US DOE.

  17. Catalyst Additives to Enhance Mercury Oxidation and Capture

    SciTech Connect

    Thomas K. Gale

    2006-06-30

    Catalysis is the key fundamental ingredient to convert elemental mercury in coal-fired power stations into its oxidized forms that are more easily captured by sorbents, ESPs, baghouses, and wet scrubbers, whether the catalyst be unburned carbon (UBC) in the ash or vanadium pentoxide in SCR catalysts. This project has investigated several different types of catalysts that enhance mercury oxidation in several different ways. The stated objective of this project in the Statement of Objectives included testing duct-injection catalysts, catalyst-sorbent hybrids, and coated low-pressure-drop screens. Several different types of catalysts were considered for duct injection, including different forms of iron and carbon. Duct-injection catalysts would have to be inexpensive catalysts, as they would not be recycled. Iron and calcium had been shown to catalyze mercury oxidation in published bench-scale tests. However, as determined from results of an on-going EPRI/EPA project at Southern Research, while iron and calcium did catalyze mercury oxidation, the activity of these catalysts was orders of magnitude below that of carbon and had little impact in the short residence times available for duct-injected catalysts or catalyst-sorbent hybrids. In fact, the only catalyst found to be effective enough for duct injection was carbon, which is also used to capture mercury and remove it from the flue gas. It was discovered that carbon itself is an effective catalyst-sorbent hybrid. Bench-scale carbon-catalyst tests were conducted, to obtain kinetic rates of mercury adsorption (a key step in the catalytic oxidation of mercury by carbon) for different forms of carbon. All carbon types investigated behaved in a similar manner with respect to mercury sorption, including the effect of temperature and chlorine concentration. Activated carbon was more effective at adsorbing mercury than carbon black and unburned carbon (UBC), because their internal surface area of activated carbon was

  18. Enhanced photothermal effect of plasmonic nanoparticles coated with reduced graphene oxide.

    PubMed

    Lim, Dong-Kwon; Barhoumi, Aoune; Wylie, Ryan G; Reznor, Gally; Langer, Robert S; Kohane, Daniel S

    2013-09-11

    We report plasmonic gold nanoshells and nanorods coated with reduced graphene oxide that produce an enhanced photothermal effect when stimulated by near-infrared (NIR) light. Electrostatic interactions between nanosized graphene oxide and gold nanoparticles followed by in situ chemical reduction generated reduced graphene oxide-coated nanoparticles; the coating was demonstrated using Raman and HR-TEM. Reduced graphene oxide-coated gold nanoparticles showed enhanced photothermal effect compared to noncoated or nonreduced graphene oxide-coated gold nanoparticles. Reduced graphene oxide-coated gold nanoparticles killed cells more rapidly than did noncoated or nonreduced graphene oxide-coated gold nanoparticles.

  19. Using slow-release permanganate candles to remove TCE from a low permeable aquifer at a former landfill.

    PubMed

    Christenson, Mark D; Kambhu, Ann; Comfort, Steve D

    2012-10-01

    Past disposal of industrial solvents into unregulated landfills is a significant source of groundwater contamination. In 2009, we began investigating a former unregulated landfill with known trichloroethene (TCE) contamination. Our objective was to pinpoint the location of the plume and treat the TCE using in situ chemical oxidation (ISCO). We accomplished this by using electrical resistivity imaging (ERI) to survey the landfill and map the subsurface lithology. We then used the ERI survey maps to guide direct push groundwater sampling. A TCE plume (100-600 μg L(-1)) was identified in a low permeable silty-clay aquifer (K(h)=0.5 md(-1)) that was within 6m of ground surface. To treat the TCE, we manufactured slow-release potassium permanganate candles (SRPCs) that were 91.4 cm long and either 5. cm or 7.6 cm in dia. For comparison, we inserted equal masses of SRPCs (7.6-cm versus 5.1-cm dia) into the low permeable aquifer in staggered rows that intersected the TCE plume. The 5.1-cm dia candles were inserted using direct push rods while the 7.6-cm SRPCs were placed in 10 permanent wells. Pneumatic circulators that emitted small air bubbles were placed below the 7.6-cm SRPCs in the second year. Results 15 months after installation showed significant TCE reductions in the 7.6-cm candle treatment zone (67-85%) and between 10% and 66% decrease in wells impacted by the direct push candles. These results support using slow-release permanganate candles as a means of treating chlorinated solvents in low permeable aquifers. Copyright © 2012 Elsevier Ltd. All rights reserved.

  20. Detection of single base mismatches of thymine and cytosine residues by potassium permanganate and hydroxylamine in the presence of tetralkylammonium salts.

    PubMed Central

    Gogos, J A; Karayiorgou, M; Aburatani, H; Kafatos, F C

    1990-01-01

    In the presence of tetramethylammonium chloride, potassium permanganate specifically modifies mismatched thymines. Similarly, the modification of mismatched cytosines by hydroxylamine was enhanced by tetraethylammonium chloride. Modification followed by piperidine cleavage permits specific identification of the T and C mismatches and by extension, when the opposite DNA strand is analyzed, of A and G mismatches as well. These reactions can be performed conveniently with DNA immobilized on Hybond M-G paper. We describe conditions that exploit these reactions to detect mismatches, e.g. point mutations or genetic polymorphisms, using either synthetic oligonucleotide probes or PCR amplification of specific genomic DNA sequences. Images PMID:2263445

  1. Chemiluminescence detection of cannabinoids and related compounds with acidic potassium permanganate.

    PubMed

    Holland, Brendan J; Francis, Paul S; Li, Bingshan; Tsuzuki, Takuya; Adcock, Jacqui L; Barnett, Neil W; Conlan, Xavier A

    2012-01-01

    This is the first report of chemiluminescence from the reaction of cannabinoids with acidic potassium permanganate, which we have applied to the high performance liquid chromatography (HPLC) determination of cannabidiol (CBD) in industrial-grade hemp. The intensities of the light-producing reactions with two commercially available cannabinoid standards were compared to that of seven model phenolic analytes. Resorcinol, representing the parent phenolic moiety of the cannabinoid class, was shown to react with the permanganate reagents in a manner more similar to phenol than to its hydroxyphenol positional isomers, pyrocatechol and hydroquinone. Alkyl substituents on the phenolic ring, however, have a considerable impact on emission intensity that is dependent upon the position of the groups and the composition of the permanganate reagent. This analytical approach has potential for the determination of other cannabinoids including Δ(9) -tetrahydrocannabinol in drug-grade cannabis. Copyright © 2012 John Wiley & Sons, Ltd.

  2. Significant enhancement of photovoltage in artificially designed perovskite oxide structures

    NASA Astrophysics Data System (ADS)

    Zhou, Wen-jia; Jin, Kui-juan; Guo, Hai-zhong; He, Xu; He, Meng; Xu, Xiu-lai; Lu, Hui-bin; Yang, Guo-zhen

    2015-03-01

    La0.9Sr0.1MnO3/insulator/SrNb0.007Ti0.993O3 multilayer and La0.9Sr0.1MnO3/SrNb0.007Ti0.993O3/In2O3:SnO2(ITO)/La0.9Sr0.1MnO3/SrNb0.007Ti0.993O3 multilayer structures were designed to enhance the photovoltage. The photovoltages of these two structures under an illumination of 308 nm laser are 410 and 600 mV, respectively. The latter is 20 times larger than that (30 mV) observed in La0.9Sr0.1MnO3/SrNb0.007Ti0.993O3 single junction. The origin of such significant enhancement of photovoltage is discussed in this letter. These results suggest that the photoelectric property of perovskite oxides could be much improved by artificial structure designing. The enhanced photovoltaic effects have potential applications in the ultraviolet photodetection and solar cells.

  3. Enhanced Osteogenesis by Reduced Graphene Oxide/Hydroxyapatite Nanocomposites

    PubMed Central

    Lee, Jong Ho; Shin, Yong Cheol; Lee, Sang-Min; Jin, Oh Seong; Kang, Seok Hee; Hong, Suck Won; Jeong, Chang-Mo; Huh, Jung Bo; Han, Dong-Wook

    2015-01-01

    Recently, graphene-based nanomaterials, in the form of two dimensional substrates or three dimensional foams, have attracted considerable attention as bioactive scaffolds to promote the differentiation of various stem cells towards specific lineages. On the other hand, the potential advantages of using graphene-based hybrid composites directly as factors inducing cellular differentiation as well as tissue regeneration are unclear. This study examined whether nanocomposites of reduced graphene oxide (rGO) and hydroxyapatite (HAp) (rGO/HAp NCs) could enhance the osteogenesis of MC3T3-E1 preosteoblasts and promote new bone formation. When combined with HAp, rGO synergistically promoted the spontaneous osteodifferentiation of MC3T3-E1 cells without hindering their proliferation. This enhanced osteogenesis was corroborated from determination of alkaline phosphatase activity as early stage markers of osteodifferentiation and mineralization of calcium and phosphate as late stage markers. Immunoblot analysis showed that rGO/HAp NCs increase the expression levels of osteopontin and osteocalcin significantly. Furthermore, rGO/HAp grafts were found to significantly enhance new bone formation in full-thickness calvarial defects without inflammatory responses. These results suggest that rGO/HAp NCs can be exploited to craft a range of strategies for the development of novel dental and orthopedic bone grafts to accelerate bone regeneration because these graphene-based composite materials have potentials to stimulate osteogenesis. PMID:26685901

  4. Enhanced Osteogenesis by Reduced Graphene Oxide/Hydroxyapatite Nanocomposites.

    PubMed

    Lee, Jong Ho; Shin, Yong Cheol; Lee, Sang-Min; Jin, Oh Seong; Kang, Seok Hee; Hong, Suck Won; Jeong, Chang-Mo; Huh, Jung Bo; Han, Dong-Wook

    2015-12-21

    Recently, graphene-based nanomaterials, in the form of two dimensional substrates or three dimensional foams, have attracted considerable attention as bioactive scaffolds to promote the differentiation of various stem cells towards specific lineages. On the other hand, the potential advantages of using graphene-based hybrid composites directly as factors inducing cellular differentiation as well as tissue regeneration are unclear. This study examined whether nanocomposites of reduced graphene oxide (rGO) and hydroxyapatite (HAp) (rGO/HAp NCs) could enhance the osteogenesis of MC3T3-E1 preosteoblasts and promote new bone formation. When combined with HAp, rGO synergistically promoted the spontaneous osteodifferentiation of MC3T3-E1 cells without hindering their proliferation. This enhanced osteogenesis was corroborated from determination of alkaline phosphatase activity as early stage markers of osteodifferentiation and mineralization of calcium and phosphate as late stage markers. Immunoblot analysis showed that rGO/HAp NCs increase the expression levels of osteopontin and osteocalcin significantly. Furthermore, rGO/HAp grafts were found to significantly enhance new bone formation in full-thickness calvarial defects without inflammatory responses. These results suggest that rGO/HAp NCs can be exploited to craft a range of strategies for the development of novel dental and orthopedic bone grafts to accelerate bone regeneration because these graphene-based composite materials have potentials to stimulate osteogenesis.

  5. Control of Nitrogen Oxide Emissions by Hydrogen Peroxide-Enhanced Gas-Phase Oxidation Of Nitric Oxide.

    PubMed

    Kasper, John M; Iii, Christian A Clausen; Cooper, C David

    1996-02-01

    Nitrogen oxides (NOX) and sulfur oxides (SOX) are criteria air pollutants, emitted in large quantities from fossil-fueled electric power plants. Emissions of SOX are currently being reduced significantly in many places by wet scrubbing of the exhaust or flue gases, but most of the NOX in the flue gases is NO, which is so insoluble that it is virtually impossible to scrub. Consequently, NOX control is mostly achieved by using combustion modifications to limit the formation of NOX, or by using chemical reduction techniques to reduce NOX to N2. Low NOX burners are relatively inexpensive but can only achieve about 50% reduction in NOX emissions; selective catalytic reduction (SCR) can achieve high reductions but is very expensive. The removal of NOX in wet scrubbers could be greatly enhanced by gas-phase oxidation of the NO to NO2, HNO2, and HNO3 (the acid gases are much more soluble in water than NO). This oxidation is accomplished by injecting liquid hydrogen peroxide into the flue gas; the H2O2 vaporizes and dissociates into hydroxyl radicals. The active OH radicals then oxidize the NO and NO2. This NOX control technique might prove economically feasible at power plants with existing SO2 scrubbers. The higher chemical costs for H2O2 would be balanced by the investment cost savings, compared with an alternative such as SCR. The oxidation of NOX by using hydrogen peroxide has been demonstrated in a laboratory quartz tube reactor. NO conversions of 97% and 75% were achieved at hydrogen peroxide/NO mole ratios of 2.6 and 1.6, respectively. The reactor conditions (500 °C, a pressure of one atmosphere, and 0.7 seconds residence time) are representative of flue gas conditions for a variety of combustion sources. The oxidized NOX species were removed by caustic water scrubbing.

  6. Sodium perxenate permits rapid oxidation of manganese for easy spectrophotometric determination

    NASA Technical Reports Server (NTRS)

    Bane, R. W.

    1967-01-01

    Sodium perxenate oxidizes manganese to permanganate almost instantaneously in dilute acid solution and without a catalyst. A solution is prepared by dissolving 200 mg of sodium perxenate in distilled water and diluting to 100 ml.

  7. A Replacement for the Silt Density Index: Permanganate Demand to Predict Reverse Osmosis Membrane Fouling.

    DTIC Science & Technology

    1983-10-13

    AD-Ai35 437 A REPLACEMENT FOR THE SILT DENSITY INDEX - PERMANGANATE 1/3 DEMAND TO PREDICT -(U) AIR FORCE INST OF TECH WJRIGHT-PATTERSON RFB OH R...72DSTPEORPOT&EIOCJED 4. TITLE (ored Subtitle)S TYEO RP RT& EIDC VRD A Replacement For The Silt Density Index : D 1q ?S/DISSERTATION Permanganate Demand To...the reduction in 4solvent flow by an increase in the osmotic pressure at the membrane. The Silt Density Index (SDI) is a membrane test that has come

  8. [Complication following the vaginal use of potassium permanganate for an abortion].

    PubMed

    Atanasov, A; Katsulov, A; Pranchev, N; Katranushkova, N

    1981-01-01

    Complications after abortifacient use of potassium permanganate in a 22-year old woman are described. Approximately 1 month prior to admission, the patient placed in the vagina a bag with potassium permanganate for 12 hours. Gynecological examination showed stenosis of the vagina, enlargement of the uterus, and adhesions in the cervix and vagina. The patient underwent surgical separation of the vagina, daily irrigations of the vagina, and postoperative administration of ampilillin. Microbiological analysis of the vaginal discharge showed the presence of bacteroides melaninogenics and Peptostreptococcus sensitive to ampicillin, chloramphenicol, and cephalosporin. These findings indicate the role of chemical injury of the vagina in pathogenesis of the endogenous anaerobic genital infection.

  9. A graphene oxide/amidoxime hydrogel for enhanced uranium capture

    PubMed Central

    Wang, Feihong; Li, Hongpeng; Liu, Qi; Li, Zhanshuang; Li, Rumin; Zhang, Hongsen; Liu, Lianhe; Emelchenko, G. A.; Wang, Jun

    2016-01-01

    The efficient development of selective materials for the recovery of uranium from nuclear waste and seawater is necessary for their potential application in nuclear fuel and the mitigation of nuclear pollution. In this work, a graphene oxide/amidoxime hydrogel (AGH) exhibits a promising adsorption performance for uranium from various aqueous solutions, including simulated seawater. We show high adsorption capacities (Qm = 398.4 mg g−1) and high % removals at ppm or ppb levels in aqueous solutions for uranium species. In the presence of high concentrations of competitive ions such as Mg2+, Ca2+, Ba2+ and Sr2+, AGH displays an enhanced selectivity for uranium. For low uranium concentrations in simulated seawater, AGH binds uranium efficiently and selectively. The results presented here reveal that the AGH is a potential adsorbent for remediating nuclear industrial effluent and adsorbing uranium from seawater. PMID:26758649

  10. Enhanced optical constants of nanocrystalline yttrium oxide thin films

    SciTech Connect

    Ramana, C. V.; Mudavakkat, V. H.; Bharathi, K. Kamala; Atuchin, V. V.; Pokrovsky, L. D.; Kruchinin, V. N.

    2011-01-17

    Yttrium oxide (Y{sub 2}O{sub 3}) films with an average crystallite-size (L) ranging from 5 to 40 nm were grown by sputter-deposition onto Si(100) substrates. The optical properties of grown Y{sub 2}O{sub 3} films were evaluated using spectroscopic ellipsometry measurements. The size-effects were significant on the optical constants and their dispersion profiles of Y{sub 2}O{sub 3} films. A significant enhancement in the index of refraction (n) is observed in well-defined Y{sub 2}O{sub 3} nanocrystalline films compared to that of amorphous Y{sub 2}O{sub 3}. A direct, linear L-n relationship found for Y{sub 2}O{sub 3} films suggests that tuning optical properties for desired applications can be achieved by controlling the size at the nanoscale dimensions.

  11. Porous platinum mesoflowers with enhanced activity for methanol oxidation reaction

    SciTech Connect

    Zhuang Lina; Wang Wenjin; Hong Feng; Yang Shengchun; You Hongjun; Fang Jixiang; Ding Bingjun

    2012-07-15

    Porous Pt and Pt-Ag alloy mesoflowers (MFs) with about 2 {mu}m in diameter and high porosity were synthesized using Ag mesoflowers as sacrificial template by galvanic reaction. The silver content in Pt-Ag alloys can be facilely controlled by nitric acid treatment. And the pure Pt MFs can be obtained by selective removal of silver element from Pt{sub 72}Ag{sub 28} MFs electrochemically. Both Pt{sub 45}Ag{sub 55}, Pt{sub 72}Ag{sub 28} and pure Pt show a high catalytic performance in methanol oxidation reaction (MOR). Especially, pure Pt MFs exhibited a 2 to 3 times current density enhancement in MOR compared with the commercial used Pt black, which can be attributed to their porous nanostructure with 3-dimentional nature and small crystal sizes. - Graphical Abstract: The CVs of MOR on Pt (red) and Pt black (green) catalysts in 0.1 M HClO{sub 4} and 0.5 M CH{sub 3}OH for specific mass current. The insert shows the SEM images of two porous Pt MFs. Platinum mesoflowers (MFs) with about 2 {mu}m in diameter and high porosity were synthesised with Ag mesoflowers as sacrificial template by galvanic replacement. The porous Pt MFs exhibited a more than 3 times enhancement in electrocatalytic performance for methanol oxidation reaction compared the commercial used Pt black. Highlights: Black-Right-Pointing-Pointer Porous Pt and Pt-Ag mesoflowers (MFs) were synthesized using Ag MFs sacrifical template. Black-Right-Pointing-Pointer Pt MFs presents an improved catalytic activity in MOR compared with Pt black. Black-Right-Pointing-Pointer We provided a facile approach for the development of high performance Pt electrocatalysts for fuel cells.

  12. 17β-Estradiol enhances sulforaphane cardioprotection against oxidative stress.

    PubMed

    Angeloni, Cristina; Teti, Gabriella; Barbalace, Maria Cristina; Malaguti, Marco; Falconi, Mirella; Hrelia, Silvana

    2017-01-12

    The lower incidence of ischemic heart disease in female with respect to male gender suggests the possibility that female sex hormones could have specific effects in cardiovascular protection. 17β-Estradiol is the predominant premenopausal circulating form of estrogen and has a protective role on the cardiovascular system. Recent evidences suggest that gender can influence the response to cardiovascular medications; therefore, we hypothesized that sex hormones could also modulate the cardioprotective effects of nutraceutical compounds, such as the isothiocyanate sulforaphane, present in Brassica vegetables. This study was designed to explore the protective effects of sulforaphane in the presence of 17β-estradiol against H2O2-induced oxidative stress in primary cultures of rat cardiomyocytes. Interestingly, 17β-estradiol enhanced sulforaphane protective activity against H2O2-induced cell death with respect to sulforaphane or 17β-estradiol alone as measured by 3-(4,5-dimethylthiazol-2-yl)-2,5diphenyl-tetrazolium bromide and lactate dehydrogenase assays. Moreover, 17β-estradiol boosted sulforaphane ability to counteract oxidative stress, reducing intracellular reactive oxygen species and 8-hydroxy-2'-deoxyguanosine levels and increasing the expression of phase II enzymes. Using specific antagonists of estrogen receptor α and β, we observed that these effects are not mediated by estrogen receptors. Otherwise, ERK1/2 and Akt signaling pathways seem to be involved, as the presence of specific inhibitors of these kinases reduced the protective effect of sulforaphane in the presence of 17β-estradiol. Sulforaphane and 17β-estradiol co-treatment counteracted cell morphology alterations induced by H2O2 as evidenced by transmission electron microscopy. Our results demonstrated, for the first time, that estrogens could enhance sulforaphane protective effects, suggesting that nutraceutical efficacy might be modulated by sex hormones.

  13. Enhanced thermoelectric properties of graphene oxide patterned by nanoroads.

    PubMed

    Zhou, Si; Guo, Yu; Zhao, Jijun

    2016-04-21

    The thermoelectric properties of two-dimensional (2D) materials are of great interest for both fundamental science and device applications. Graphene oxide (GO), whose physical properties are highly tailorable by chemical and structural modifications, is a potential 2D thermoelectric material. In this report, we pattern nanoroads on GO sheets with epoxide functionalization, and investigate their ballistic thermoelectric transport properties based on density functional theory and the nonequilibrium Green's function method. These graphene oxide nanoroads (GONRDs) are all semiconductors with their band gaps tunable by the road width, edge orientation, and the structure of the GO matrix. These nanostructures show appreciable electrical conductance at certain doping levels and enhanced thermopower of 127-287 μV K(-1), yielding a power factor 4-22 times of the graphene value; meanwhile, the lattice thermal conductance is remarkably reduced to 15-22% of the graphene value; consequently, attaining the figure of merit of 0.05-0.75. Our theoretical results are not only helpful for understanding the thermoelectric properties of graphene and its derivatives, but also would guide the theoretical design and experimental fabrication of graphene-based thermoelectric devices of high performance.

  14. Impaired cardiac mitochondrial oxidative phosphorylation and enhanced mitochondrial oxidative stress in feline hypertrophic cardiomyopathy.

    PubMed

    Christiansen, Liselotte B; Dela, Flemming; Koch, Jørgen; Hansen, Christina N; Leifsson, Pall S; Yokota, Takashi

    2015-05-15

    Mitochondrial dysfunction and oxidative stress are important players in the development of various cardiovascular diseases, but their roles in hypertrophic cardiomyopathy (HCM) remain unknown. We examined whether mitochondrial oxidative phosphorylation (OXPHOS) capacity was impaired with enhanced mitochondrial oxidative stress in HCM. Cardiac and skeletal muscles were obtained from 9 domestic cats with spontaneously occurring HCM with preserved left ventricular systolic function and from 15 age-matched control cats. Mitochondrial OXPHOS capacities with nonfatty acid and fatty acid substrates in permeabilized fibers and isolated mitochondria were assessed using high-resolution respirometry. ROS release originating from isolated mitochondria was assessed by spectrofluorometry. Thiobarbituric acid-reactive substances were also measured as a marker of oxidative damage. Mitochondrial ADP-stimulated state 3 respiration with complex I-linked nonfatty acid substrates and with fatty acid substrates, respectively, was significantly lower in the hearts of HCM cats compared with control cats. Mitochondrial ROS release during state 3 with complex I-linked substrates and thiobarbituric acid-reactive substances in the heart were significantly increased in cats with HCM. In contrast, there were no significant differences in mitochondrial OXPHOS capacity, mitochondrial ROS release, and oxidative damage in skeletal muscle between groups. Mitochondrial OXPHOS capacity with both nonfatty acid substrates and fatty acid substrates was impaired with increased mitochondrial ROS release in the feline HCM heart. These findings provide new insights into the pathophysiology of HCM and support the hypothesis that restoration of the redox state in the mitochondria is beneficial in the treatment of HCM. Copyright © 2015 the American Physiological Society.

  15. Trolox enhances curcumin's cytotoxicity through induction of oxidative stress.

    PubMed

    Zheng, Jie; Payne, Kelsey; Taggart, Jori E; Jiang, Hongchao; Lind, Stuart E; Ding, Wei-Qun

    2012-01-01

    Curcumin, a natural polyphenol in the spice turmeric, has been found to exhibit anticancer activity. Although curcumin is generally considered an antioxidant, it is also able to elicit apoptosis through the generation of ROS, thereby functioning as a pro-oxidant in cancer cells. The present study investigated the effects of antioxidant pretreatment on curcumin-induced cytotoxicity in the human cancer cell lines A2780, MCF-7, and MDA-MB-231. Cytotoxicity was enhanced by trolox, vitamin C or vitamin E; trolox, a water soluble vitamin E derivative, was the most potent. The combination of curcumin (10 μM) and trolox (10-50 μM) induced apoptosis of cancer cells as evidenced by PARP cleavage and caspase-3 activation. Furthermore, expression of the pro-apoptotic protein Bad was up-regulated and expression of the anti-apoptotic proteins Bcl-2 and Bcl-xl was down-regulated in cells that had been treated with trolox plus curcumin. ROS generation was detected in curcumin-treated cells and was significantly enhanced when cells were treated with trolox plus curcumin. Exogenous catalase or SOD1 did not alter cytotoxicity, while over-expression of either catalase or SOD1 did, pointing to the importance of intracellular hydrogen peroxide generation in cell killing. In conclusion, we demonstrated for the first time that antioxidants such as trolox can potentiate cancer cell killing by curcumin, a finding which may help in the development of novel drug combination therapies.

  16. Enhanced wet air oxidation : synergistic rate acceleration upon effluent recirculation

    Treesearch

    Matthew J. Birchmeier; Charles G. Hill; Carl J. Houtman; Rajai H. Atalla; Ira A. Weinstock

    2000-01-01

    Wet air oxidation (WAO) reactions of cellobiose, phenol, and syringic acid were carried out under mild conditions (155°C; 0.93MPa 02; soluble catalyst, Na5[PV2Mo10O40]). Initial oxidation rates were rapid but decreased to small values as less reactive oxidation products accumulated. Recalcitrant oxidation products were consumed more rapidly, however, if additional...

  17. Preparation of amorphous electrochromic tungsten oxide and molybdenum oxide by plasma enhanced chemical vapor deposition

    SciTech Connect

    Tracy, C.E.; Benson, D.K.

    1986-09-01

    Preliminary experiments have been performed to probe the feasibility of using plasma enhanced chemical vapor deposition (PE--CVD) to prepare electrochromic thin films of tungsten oxide and molybdenum oxide by plasma reaction of WF/sub 6/, W(CO)/sub 6/, and Mo(CO)/sub 6/ with oxygen. Thin films produced in a 300 W, electrodeless, radio-frequency (rf), capacitive discharge were found to be electrochromic when tested with either liquid or solid electrolytes. Optical spectroscopy was performed on two electrochromic coatings after Li/sup +/ ion insertion from a propylene carbonate liquid electrolyte. Broad absorption peaks at --900 nm for WO/sub 3/ and 600 nm for MoO/sub 3/ were observed. Optical results for PE--CVD MoO/sub 3/ films differ from those reported for evaporated MoO/sub 3/ films which have an absorption peak at --800 nm. The shorter wavelength absorption in the PE--CVD MoO/sub 3/ films offers the potential for fabricating electrochromic devices with higher contrast ratios and less color change. Optical emission spectroscopy, Auger, and x-ray diffraction analyses indicate these thin film deposits to be predominantly amorphous tungsten and molybdenum oxides.

  18. Molecular dynamics simulation of silicon oxidation enhanced by energetic hydrogen ion irradiation

    NASA Astrophysics Data System (ADS)

    Mizotani, Kohei; Isobe, Michiro; Fukasawa, Masanaga; Nagahata, Kazunori; Tatsumi, Tetsuya; Hamaguchi, Satoshi

    2015-04-01

    Molecular dynamics numerical simulations have been performed to clarify the mechanism of enhanced oxidation in Si during silicon gate etching by HBr/O2 plasmas. Such enhanced oxidation sometimes manifests itself as Si recess during gate etching processes. When a Si substrate is subject to energetic ion bombardment together with a flux of radical species, our study has identified the cause of such enhanced oxidation in Si as enhanced O diffusion arising from the momentum transfer from energetic H atoms to O atoms on the surface or in the subsurface of the Si substrate. No chemical effect such as hydrogenation of Si plays a role for the enhanced oxidation. Simulation results are found to be in good agreement with earlier experimental observations of ion-irradiation-enhanced oxidation obtained by beam experiments.

  19. Effects of Smallmouth Buffalo and Potassium Permanganate Treatment on Plankton ans Pond Water Quality

    USDA-ARS?s Scientific Manuscript database

    Removal of intermediate hosts is one option for control of disease in channel catfish production systems. We evaluated use of predaceous fish (smallmouth buffalo) and chemical treatment (potassium permanganate) to remove snails that serve as hosts protecting Dero worms. Both methods of treatment r...

  20. Preparation and Analysis of Solid Solutions in the Potassium Perchlorate-Permanganate System.

    ERIC Educational Resources Information Center

    Johnson, Garrett K.

    1979-01-01

    Describes an experiment, designed for and tested in an advanced inorganic laboratory methods course for college seniors and graduate students, that prepares and analyzes several samples in the nearly ideal potassium perchlorate-permanganate solid solution series. The results are accounted for by a theoretical treatment based upon aqueous…

  1. Permanganate oxidizable carbon reflects a processed soil fraction that is sensitive to management

    USDA-ARS?s Scientific Manuscript database

    Permanganate oxidizable C (POXC; i.e., active C) is a relatively new method that can quantify labile soil C rapidly and inexpensively. Despite limited reports of positive correlations with particulate organic carbon (POC), microbial biomass carbon (MBC) and other soil carbon (C) fractions, little i...

  2. Effectiveness of copper sulfate and potassium permanganate on channel catfish infected with Flavobacterium columnare

    USDA-ARS?s Scientific Manuscript database

    Copper sulfate (CuSO4) and potassium permanganate (KMnO4) were evaluated for their effectiveness to curtail mortality and decrease bacterial load in fish tissues and water in channel catfish Ictalurus punctatus naturally infected with Flavobacterium columnare, the causative agent of columnaris. Fis...

  3. Potassium permanganate is not an effective pond disinfectant to control Dero digitata

    USDA-ARS?s Scientific Manuscript database

    Proliferative gill disease (PGD) is a major problem in cultured channel catfish, Ictalurus punctatus. This parasite requires Dero digitata to complete its life cycle. It is believed potassium permanganate disinfects ponds and reduces D. digitata populations, but this practice has not been verified...

  4. The effect of copper sulfate, potassium permanganate, and peracetic acid on Ichthyobodo necator in channel catfish

    USDA-ARS?s Scientific Manuscript database

    Ichthyobodo necator is a single celled biflagellate that can cause significant mortalities in fish, particularly young, tank-reared fish. Copper sulfate (CuSO4), potassium permanganate (KMnO4) and peracetic acid (PAA) were evaluated for effectiveness against Ichthybodosis in juvenile channel catfis...

  5. Preparation and Analysis of Solid Solutions in the Potassium Perchlorate-Permanganate System.

    ERIC Educational Resources Information Center

    Johnson, Garrett K.

    1979-01-01

    Describes an experiment, designed for and tested in an advanced inorganic laboratory methods course for college seniors and graduate students, that prepares and analyzes several samples in the nearly ideal potassium perchlorate-permanganate solid solution series. The results are accounted for by a theoretical treatment based upon aqueous…

  6. Permanganate Degradation of Reillex HPQ Ion Exchange Resin for Use in HB-Line

    SciTech Connect

    Walker, B.W.

    1999-06-02

    This study evaluated the use of Reillex TM HPQ resin as a replacement for the Ionac A-641 resin currently authorized for use in H B-Line. The study concentrated on the ability of the existing alkaline permanganate digestion process to convert spent resin for disposal.

  7. (-)-Epicatechin enhances fatigue resistance and oxidative capacity in mouse muscle.

    PubMed

    Nogueira, Leonardo; Ramirez-Sanchez, Israel; Perkins, Guy A; Murphy, Anne; Taub, Pam R; Ceballos, Guillermo; Villarreal, Francisco J; Hogan, Michael C; Malek, Moh H

    2011-09-15

    The flavanol (-)-epicatechin, a component of cacao (cocoa), has been shown to have multiple health benefits in humans. Using 1-year-old male mice, we examined the effects of 15 days of (-)-epicatechin treatment and regular exercise on: (1) exercise performance, (2) muscle fatigue, (3) capillarity, and (4) mitochondrial biogenesis in mouse hindlimb and heart muscles. Twenty-five male mice (C57BL/6N) were randomized into four groups: (1) water, (2) water-exercise (W-Ex), (3) (-)-epicatechin ((-)-Epi), and (4) (-)-epicatechin-exercise ((-)-Epi-Ex). Animals received 1 mg kg(-1) of (-)-epicatechin or water (vehicle) via oral gavage (twice daily). Exercise groups underwent 15 days of treadmill exercise. Significant increases in treadmill performance (∼50%) and enhanced in situ muscle fatigue resistance (∼30%) were observed with (-)-epicatechin. Components of oxidative phosphorylation complexes, mitofilin, porin, nNOS, p-nNOS, and Tfam as well as mitochondrial volume and cristae abundance were significantly higher with (-)-epicatechin treatment for hindlimb and cardiac muscles than exercise alone. In addition, there were significant increases in skeletal muscle capillarity. The combination of (-)-epicatechin and exercise resulted in further increases in oxidative phosphorylation-complex proteins, mitofilin, porin and capillarity than (-)-epicatechin alone. These findings indicate that (-)-epicatechin alone or in combination with exercise induces an integrated response that includes structural and metabolic changes in skeletal and cardiac muscles resulting in greater endurance capacity. These results, therefore, warrant the further evaluation of the underlying mechanism of action of (-)-epicatechin and its potential clinical application as an exercise mimetic.

  8. One-step sonochemical synthesis of a graphene oxide-manganese oxide nanocomposite for catalytic glycolysis of poly(ethylene terephthalate).

    PubMed

    Park, Gle; Bartolome, Leian; Lee, Kyoung G; Lee, Seok Jae; Kim, Do Hyun; Park, Tae Jung

    2012-07-07

    Ultrasound-assisted synthesis of a graphene oxide (GO)-manganese oxide nanocomposite (GO-Mn(3)O(4)) was conducted without further modification of GO or employing secondary materials. With the GO nanoplate as a support, potassium permanganate oxidizes the carbon atoms in the GO support and gets reduced to Mn(3)O(4). An intensive ultrasound method could reduce the number of reaction steps and temperature, enhance the reaction rate and furthermore achieve a Mn(3)O(4) phase. The composite was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The coverage and crystallinity of Mn(3)O(4) were controlled by changing the ratio of permanganate to GO dispersion. The synthesized nanocomposite was used as a catalyst for poly(ethylene terephthalate) (PET) depolymerization into its monomer, bis(2-hydroxylethyl) terephthalate (BHET). The highest monomer yield of 96.4% was obtained with the nanocomposite containing the lowest amount of Mn(3)O(4), while PET glycolysis with the Mn(3)O(4) without GO yielded 82.7% BHET.

  9. Oxide nanomembrane hybrids with enhanced mechano- and thermo-sensitivity for semitransparent epidermal electronics.

    PubMed

    Park, Minjoon; Do, Kyungsik; Kim, Jaemin; Son, Donghee; Koo, Ja Hoon; Park, Jinkyung; Song, Jun-Kyul; Kim, Ji Hoon; Lee, Minbaek; Hyeon, Taeghwan; Kim, Dae-Hyeong

    2015-05-01

    Oxide nanomembrane hybrids with enhanced mechano- and thermo-sensitivity for semitransparent epidermal electronics are developed. The use of nanomaterials (single wall nanotubes and silver nanoparticles) embedded in the oxide nanomembranes significantly enhances mechanical and thermal sensitivities. These mechanical and thermal sensors are utilized in wheelchair control and hypothermia detection, which are useful for patients with strokes.

  10. Injectable silica-permanganate gel as a slow-release MnO4(-) source for groundwater remediation: rheological properties and release dynamics.

    PubMed

    Yang, S; Oostrom, M; Truex, M J; Li, G; Zhong, L

    2016-02-01

    Injectable slow-release permanganate gels (ISRPGs), formed by mixing aqueous KMnO4 solution with fumed silica powders, may have potential applications in remediating chlorinated solvent plumes in groundwater. A series of batch, column, and two-dimensional (2-D) flow cell experiments has been completed to characterize the ISRPG and study the release of permanganate (MnO4(-)) under a variety of conditions. The experiments have provided information on ISRPG rheology, MnO4(-) release dynamics and distribution in porous media, and trichloroethene (TCE) destruction by the ISRPG-released oxidant. The gel possesses shear thinning characteristics, resulting in a relatively low viscosity during mixing, and facilitating subsurface injection and distribution. Batch tests clearly showed that MnO4(-) diffused out from the ISRPG into water. During this process, the gel did not dissolve or disperse into water, but rather maintained its initial shape. Column experiments demonstrated that MnO4(-) release from the ISRPG lasted considerably longer than that from an aqueous solution. In addition, due to the longer release duration, TCE destruction by ISRPG-released MnO4(-) was considerably more effective than that when MnO4(-) was delivered using aqueous solution injection. In the 2-D flow cell experiments, it was demonstrated that ISRPGs released a long-lasting, low-concentration MnO4(-) plume potentially sufficient for sustainable remediation in aquifers.

  11. Al-doped zinc oxide nanocomposites with enhanced thermoelectric properties.

    PubMed

    Jood, Priyanka; Mehta, Rutvik J; Zhang, Yanliang; Peleckis, Germanas; Wang, Xiaolin; Siegel, Richard W; Borca-Tasciuc, Theo; Dou, Shi Xue; Ramanath, Ganpati

    2011-10-12

    ZnO is a promising high figure-of-merit (ZT) thermoelectric material for power harvesting from heat due to its high melting point, high electrical conductivity σ, and Seebeck coefficient α, but its practical use is limited by a high lattice thermal conductivity κ(L). Here, we report Al-containing ZnO nanocomposites with up to a factor of 20 lower κ(L) than non-nanostructured ZnO, while retaining bulklike α and σ. We show that enhanced phonon scattering promoted by Al-induced grain refinement and ZnAl(2)O(4) nanoprecipitates presages ultralow κ ∼ 2 Wm( -1) K(-1) at 1000 K. The high α∼ -300 μV K(-1) and high σ ∼ 1-10(4) Ω(-1 )m(-1) result from an offsetting of the nanostructuring-induced mobility decrease by high, and nondegenerate, carrier concentrations obtained via excitation from shallow Al donor states. The resultant ZT ∼ 0.44 at 1000 K is 50% higher than that for the best non-nanostructured counterpart material at the same temperature and holds promise for engineering advanced oxide-based high-ZT thermoelectrics for applications.

  12. Enhanced Photoelectrochemical Performance of Cuprous Oxide/Graphene Nanohybrids

    PubMed Central

    2017-01-01

    Combination of an oxide semiconductor with a highly conductive nanocarbon framework (such as graphene or carbon nanotubes) is an attractive avenue to assemble efficient photoelectrodes for solar fuel generation. To fully exploit the possible synergies of the hybrid formation, however, precise knowledge of these systems is required to allow rational design and morphological engineering. In this paper, we present the controlled electrochemical deposition of nanocrystalline p-Cu2O on the surface of different graphene substrates. The developed synthetic protocol allowed tuning of the morphological features of the hybrids as deduced from electron microscopy. (Photo)electrochemical measurements (including photovoltammetry, electrochemical impedance spectroscopy, photocurrent transient analysis) demonstrated better performance for the 2D graphene containing photoelectrodes, compared to the bare Cu2O films, the enhanced performance being rooted in suppressed charge carrier recombination. To elucidate the precise role of graphene, comparative studies were performed with carbon nanotube (CNT) films and 3D graphene foams. These studies revealed, after allowing for the effect of increased surface area, that the 3D graphene substrate outperformed the other two nanocarbons. Its interconnected structure facilitated effective charge separation and transport, leading to better harvesting of the generated photoelectrons. These hybrid assemblies are shown to be potentially attractive candidates in photoelectrochemical energy conversion schemes, namely CO2 reduction. PMID:28460518

  13. Enhanced Photoelectrochemical Performance of Cuprous Oxide/Graphene Nanohybrids.

    PubMed

    Kecsenovity, Egon; Endrődi, Balázs; Tóth, Péter S; Zou, Yuqin; Dryfe, Robert A W; Rajeshwar, Krishnan; Janáky, Csaba

    2017-05-17

    Combination of an oxide semiconductor with a highly conductive nanocarbon framework (such as graphene or carbon nanotubes) is an attractive avenue to assemble efficient photoelectrodes for solar fuel generation. To fully exploit the possible synergies of the hybrid formation, however, precise knowledge of these systems is required to allow rational design and morphological engineering. In this paper, we present the controlled electrochemical deposition of nanocrystalline p-Cu2O on the surface of different graphene substrates. The developed synthetic protocol allowed tuning of the morphological features of the hybrids as deduced from electron microscopy. (Photo)electrochemical measurements (including photovoltammetry, electrochemical impedance spectroscopy, photocurrent transient analysis) demonstrated better performance for the 2D graphene containing photoelectrodes, compared to the bare Cu2O films, the enhanced performance being rooted in suppressed charge carrier recombination. To elucidate the precise role of graphene, comparative studies were performed with carbon nanotube (CNT) films and 3D graphene foams. These studies revealed, after allowing for the effect of increased surface area, that the 3D graphene substrate outperformed the other two nanocarbons. Its interconnected structure facilitated effective charge separation and transport, leading to better harvesting of the generated photoelectrons. These hybrid assemblies are shown to be potentially attractive candidates in photoelectrochemical energy conversion schemes, namely CO2 reduction.

  14. Nitrogen oxides removal by pulsed corona enhanced wet electrostatics precipitation

    SciTech Connect

    Tseng, C.H.; Keener, T.C.; Khang, S.J.

    1999-07-01

    This paper presents the results of a bench-scale pulsed-corona enhanced wet electrostatic precipitator (wESP) application for removal of nitrogen oxides. This wESP is designed to operate wet/dry, positive/negative, and pulsed/non-pulsed conditions. The applied pulsed voltage is varied from 0 to 60 kV at 70 Hz. Gas flow rate is a nominal 7 m{sup 3}/hr and the collecting electrode area is 0.20 m{sup 2}. A simulated flue gas with NO concentration up to 1,200 ppm{sub v} has been used to determine the feasibility of NO{sub x} removal in the wESP. NO has to be oxidized to N{sub 2} before any removal takes place. NO{sub x} removal efficiency increased with gas residence time, inlet NO concentration and applied corona power. In the air stream with 10 seconds gas residence time, up to 20% of 1,000 ppm NO (or 22% NO{sub x}) was removed from an air stream of 1.9x10{sup {minus}3} m{sup 3}/s with a water flow of 6.3 x 10{sup {minus}5} m{sup 3}/sec and 20 W, 70 Hz pulsed corona. Both ammonia and ozone injections improve the NO{sub x} removal for both the corona and non-corona cases. With the inclusion of NH{sub 3} (NH{sub 3}/NO{sub x} ratio 1.3) and 25 watts corona power, NO removal efficiency was increased from 28% to 57%. The amount of in-situ ozone is not enough to be considered as a major NO{sub x} removal mechanism in this wESP. However, the additional injection of ozone improves the NO removal from 29% to 38% for both the corona and non-corona cases. When the oxygen concentration is dropped to 3% in a simulated flue gas with 12% CO{sub 2} and 800 ppm NO and 70% relative humidity at 11.5 s of gas residence time, the removal efficiency of NO is only 5%. Adding NH{sub 3} (NH{sub 3}/NO{sub x} ratio 1) at 76 watts corona power, NO removal is increased to 13%.

  15. Enhanced gastric nitric oxide synthase activity in duodenal ulcer patients.

    PubMed Central

    Rachmilewitz, D; Karmeli, F; Eliakim, R; Stalnikowicz, R; Ackerman, Z; Amir, G; Stamler, J S

    1994-01-01

    Nitric oxide, the product of nitric oxide synthase in inflammatory cells, may have a role in tissue injury through its oxidative metabolism. Nitric oxide may have a role in the pathogenesis of duodenal ulcer and may be one of the mechanisms responsible for the association between gastric infection with Helicobacter pylori and peptic disease. In this study, calcium independent nitric oxide synthase activity was detected in human gastric mucosa suggesting expression of the inducible isoform. In 17 duodenal ulcer patients gastric antral and fundic nitric oxide synthase activity was found to be two and 1.5-fold respectively higher than its activity in the antrum and fundus of 14 normal subjects (p < 0.05). H pylori was detected in the antrum of 15 of 17 duodenal ulcer patients and only in 7 of 14 of the control subjects. Antral nitric oxide synthase activity in H pylori positive duodenal ulcer patients was twofold higher than in H pylori positive normal subjects (p < 0.05). In duodenal ulcer patients antral and fundic nitric oxide synthase activity resumed normal values after induction of ulcer healing with ranitidine. Eradication of H pylori did not further affect gastric nitric oxide synthase activity. These findings suggest that in duodenal ulcer patients stimulated gastric mucosal nitric oxide synthase activity, though independent of the H pylori state, may contribute to the pathogenesis of the disease. PMID:7525417

  16. Compositions comprising enhanced graphene oxide structures and related methods

    DOEpatents

    Kumar, Priyank Vijaya; Bardhan, Neelkanth M.; Belcher, Angela; Grossman, Jeffrey

    2016-12-27

    Embodiments described herein generally relate to compositions comprising a graphene oxide species. In some embodiments, the compositions advantageously have relatively high oxygen content, even after annealing.

  17. Insight into metal-enhanced oxidation using barium on 4H-SiC surfaces

    NASA Astrophysics Data System (ADS)

    Chanthaphan, Atthawut; Katsu, Yoshihito; Hosoi, Takuji; Shimura, Takayoshi; Watanabe, Heiji

    2016-12-01

    Metal-enhanced oxidation (MEO) using ultrathin Ba layers on 4H-SiC surfaces was investigated by physical and electrical characterizations. We found that while comparable oxidation rates were enhanced for Si- and C-face surfaces even at a low temperature, significant surface and interface roughness were induced by initial MEO termed the incubation period. Depth profiling revealed that although most Ba atoms aggregated on the oxide surface, a tiny amount (˜1014 cm-2) remaining at the oxide interface was responsible for the following stable MEO reaction and the reduced interface state density with the drawbacks of degraded leakage current and breakdown characteristics of SiC-MOS devices.

  18. Catalyst Additives to Enhance Mercury Oxidation and Capture

    SciTech Connect

    Thomas K. Gale

    2005-12-31

    Preliminary research has shown that SCR catalysts employed for nitrogen-oxide reduction can effectively oxidize mercury. Three different SCR catalysts are currently being studied in this project--honeycomb-type, plate-type, and a hybrid-type catalyst. The catalysts were manufactured and supplied by Cormetech Inc., Hitachi America Ltd., and Haldor-Topsoe Inc., respectively. Parametric testing was performed to investigate the contribution of flue-gas chemistry on mercury oxidation via SCR catalysts. Future work to characterize flue gas simulations typically derived from low and high sulfur bituminous coal are being performed in a stepwise manner, to avoid the constant interruptions in testing that occur when leaks in the system are generated during temperature transitions. Specifically, chlorine concentration vs. mercury oxidation correlations will be developed for each catalyst. The contributions of temperature are also being investigated. SO2 oxidation is also being investigated for each test condition.

  19. Novel method for controlled oxidation

    SciTech Connect

    Benjamin, B.M.; Raaen, V.F.

    1981-01-01

    The purpose of this paper is to describe a novel method for the oxidative degradation of coal or other organic material. The procedure is potentially useful for structure determination. As originally conceived, this method was intended for use with aqueous potassium permanganate as oxidant, but it is equally applicable with other oxidizing agents. Sodium hyprochlorite can be substituted for KMnO/sub 4/ except that controlling the pH and monitoring the end pilot become more difficult. Results with potassium permanganate only are described here but sodium hypochlorite was tried. An advantageous feature of the method is the simultaneous removal of soluble products from further contact with oxidizing agent as the oxidizing agent attacks the substrate. In principle, the experimental approach resembles that of column chromatography. Any oxidative degradation of a natural product for structure determination is of little use if carried out too far; for example, to the smallest, most oxidation-resistant materials such as carbon dioxide, acetic acid, and benzoic acid. Potassium permanganate oxidations of reactive species such as coal and kerogen are particularly difficult to control. Partially oxidized fragments which go into solution can be attacked more effectively than the solid starting phase, a situation which results in loss of structural information. Another difficulty is that phenolic materials can undergo coupling reactions thus generating larger molecules and giving misleading results due to a larger number of substituents. The procedure used is described.

  20. Production of Metal-Free Composites Composed of Graphite Oxide and Oxidized Carbon Nitride Nanodots and Their Enhanced Photocatalytic Performances.

    PubMed

    Kim, Seung Yeon; Oh, Junghoon; Park, Sunghee; Shim, Yeonjun; Park, Sungjin

    2016-04-04

    A novel metal-free composite (GN) composed of two types of carbon-based nanomaterials, graphite oxide (GO) and 2D oxidized carbon nitride (OCN) nanodots was produced. Chemical and morphological characterizations reveal that GN contains a main component of GO with well-dispersed 2D OCN nanodots. GN shows enhanced photocatalytic performance for degrading an organic pollutant, Rhodamine B, under visible light. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. The pathophysiology of extracellular hemoglobin associated with enhanced oxidative reactions

    PubMed Central

    Rifkind, Joseph M.; Mohanty, Joy G.; Nagababu, Enika

    2015-01-01

    Hemoglobin (Hb) continuously undergoes autoxidation producing superoxide which dismutates into hydrogen peroxide (H2O2) and is a potential source for subsequent oxidative reactions. Autoxidation is most pronounced under hypoxic conditions in the microcirculation and for unstable dimers formed at reduced Hb concentrations. In the red blood cell (RBC), oxidative reactions are inhibited by an extensive antioxidant system. For extracellular Hb, whether from hemolysis of RBCs and/or the infusion of Hb-based blood substitutes, the oxidative reactions are not completely neutralized by the available antioxidant system. Un-neutralized H2O2 oxidizes ferrous and ferric Hbs to Fe(IV)-ferrylHb and OxyferrylHb, respectively. FerrylHb further reacts with H2O2 producing heme degradation products and free iron. OxyferrylHb, in addition to Fe(IV) contains a free radical that can undergo additional oxidative reactions. Fe(III)Hb produced during Hb autoxidation also readily releases heme, an additional source for oxidative stress. These oxidation products are a potential source for oxidative reactions in the plasma, but to a greater extent when the lower molecular weight Hb dimers are taken up into cells and tissues. Heme and oxyferryl have been shown to have a proinflammatory effect further increasing their potential for oxidative stress. These oxidative reactions contribute to a number of pathological situations including atherosclerosis, kidney malfunction, sickle cell disease, and malaria. The toxic effects of extracellular Hb are of particular concern with hemolytic anemia where there is an increase in hemolysis. Hemolysis is further exacerbated in various diseases and their treatments. Blood transfusions are required whenever there is an appreciable decrease in RBCs due to hemolysis or blood loss. It is, therefore, essential that the transfused blood, whether stored RBCs or the blood obtained by an Autologous Blood Recovery System from the patient, do not further increase

  2. Determination of intracellular glutathione and glutathione disulfide using high performance liquid chromatography with acidic potassium permanganate chemiluminescence detection.

    PubMed

    McDermott, Geoffrey P; Francis, Paul S; Holt, Kayla J; Scott, Kristen L; Martin, Sheree D; Stupka, Nicole; Barnett, Neil W; Conlan, Xavier A

    2011-06-21

    Measurement of glutathione (GSH) and glutathione disulfide (GSSG) is a crucial tool to assess cellular redox state. Herein we report a direct approach to determine intracellular GSH based on a rapid chromatographic separation coupled with acidic potassium permanganate chemiluminescence detection, which was extended to GSSG by incorporating thiol blocking and disulfide bond reduction. Importantly, this simple procedure avoids derivatisation of GSH (thus minimising auto-oxidation) and overcomes problems encountered when deriving the concentration of GSSG from 'total GSH'. The linear range and limit of detection for both analytes were 7.5 × 10(-7) to 1 × 10(-5) M, and 5 × 10(-7) M, respectively. GSH and GSSG were determined in cultured muscle cells treated for 24 h with glucose oxidase (0, 15, 30, 100, 250 and 500 mU mL(-1)), which exposed them to a continuous source of reactive oxygen species (ROS). Both analyte concentrations were greater in myotubes treated with 100 or 250 mU mL(-1) glucose oxidase (compared to untreated controls), but were significantly lower in myotubes treated with 500 mU mL(-1) (p < 0.05), which was rationalised by considering measurements of H(2)O(2) and cell viability. However, the GSH/GSSG ratio in myotubes treated with 100, 250 and 500 mU mL(-1) glucose oxidase exhibited a dose-dependent decrease that reflected the increase in intracellular ROS.

  3. Development of a Design Tool for Planning Aqueous Amendment Injection Systems Permanganate Design Tool

    DTIC Science & Technology

    2010-08-01

    resulting in higher effective NOD. In this project, groundwater flow, transport and reaction models ( MODFLOW and RT3D) are used to evaluate the...solute transport were simulated using the MODFLOW (Harbaugh et al., 2000) and RT3D (Clement 1997) engines within GMS (Aquaveo 2008). The chemical...numerical modeling engines MODFLOW (Harbaugh et al., 2000) 1988) and RT3D (Clement, 1997) within GMS (Aquaveo 2008). Permanganate consumption and

  4. Chemiluminescence behaviour of alkaline earth metal ions in the potassium permanganate-fluorescein reaction.

    PubMed

    Du, Jianxiu; Liu, Wenxia; Lu, Jiuru

    2003-01-01

    A chemiluminescence (CL) signal was observed when alkaline earth metal ion solution, Mg2+ or Ca2+ or Ba2+, was injected into a reaction mixture of fluorescein and potassium permanganate. A possible CL mechanism is proposed based upon the CL, fluorescence and UV-visible spectra. Furthermore, the feasibility of the application of these reactions to the analysis of these alkaline earth metal ions was evaluated and the analytical parameters of the methods were determined. Copyright 2003 John Wiley & Sons, Ltd.

  5. [Study on the determination of permanganate index by UV-Vis spectrometry].

    PubMed

    Jiang, Shao-Jie; Shi, Fu-Rong; Zheng, Huai-Li

    2009-08-01

    Permanganate index is an important parameter to evaluate the organic pollution for water sources, and the current national standard method is titration analysis which needs large sample and is complicated. A new analytical method of measuring permanganate index in surface water using UV-Vis spectrometry has thus been studied. In the laboratory work, analytical wave-length of UV-Vis spectrometry was chosen. The effect of sulfuric acid dosage, concentration and dosage of KMnO4 together with heating temperature and time was identified. In order to evaluate this new method, the linear relationship of this method was tested and the analysis results were compared with those by titration method. The selected optimum analysis parameters were: 525 nm wavelength, 25% H2SO4 dosage of 5.00 mL, 0.012 50 mol x L(-1) KMnO4 dosage of 2.00 mL, 30 min heating time at the temperature of 100 degrees C. This UV-Vis spectrometry method was successfully applied to measuring the permanganate index of the samples collected from the Jialing River and the Yangtze River. Compared with the current national standard method, this method is time and cost efficient, sensitive and precise, with low reagent usage; and is also easy to be manipulated and can be employed for online monitor, thus making it an environmental friendly analysing method.

  6. Enhanced charge trapping in bipolar spacer oxides during low-dose-rate irradiation

    SciTech Connect

    Fleetwood, D.M.; Reber, R.A. Jr.; Winokur, P.S.; Kosier, S.L.; Schrimpf, R.D.; Nowlin, R.N.; Pease, R.L.; DeLaus, M.

    1994-03-01

    Thermally-stimulated-current and capacitance-voltage measurements reveal enhanced hole trapping in bipolar spacer-oxide capacitors irradiated at 0 V at low dose rates. Possible mechanisms and implications for bipolar low-rate response are discussed.

  7. Enhanced arsenic removal using mixed metal oxide impregnated chitosan beads.

    PubMed

    Yamani, Jamila S; Miller, Sarah M; Spaulding, Matthew L; Zimmerman, Julie B

    2012-09-15

    Mixed metal oxide impregnated chitosan beads (MICB) containing nanocrystalline Al₂O₃ and nanocrystalline TiO₂ were successfully developed. This adsorbent exploits the high capacity of Al₂O₃ for arsenate and the photocatalytic activity of TiO₂ to oxidize arsenite to arsenate, resulting in a removal capacity higher than that of either metal oxide alone. The composition of the beads was optimized for maximum arsenite removal in the presence of UV light. The mechanism of removal was investigated and a mode of action was proposed wherein TiO₂ oxidizes arsenite to arsenate which is then removed from solution by Al₂O₃. Pseudo-second order kinetics were used to validate the proposed mechanism. MICB is a more efficient and effective adsorbent for arsenic than TiO₂-impregnated chitosan beads (TICB), previously reported on, yet maintains a desirable life cycle, free of complex synthesis processes, toxic materials, and energy inputs.

  8. UV/ozone-oxidized large-scale graphene platform with large chemical enhancement in surface-enhanced Raman scattering.

    PubMed

    Huh, Sung; Park, Jaesung; Kim, Young Soo; Kim, Kwang S; Hong, Byung Hee; Nam, Jwa-Min

    2011-12-27

    We fabricated a highly oxidized large-scale graphene platform using chemical vapor deposition (CVD) and UV/ozone-based oxidation methods. This platform offers a large-scale surface-enhanced Raman scattering (SERS) substrate with large chemical enhancement in SERS and reproducible SERS signals over a centimeter-scale graphene surface. After UV-induced ozone generation, ozone molecules were reacted with graphene to produce oxygen-containing groups on graphene and induced the p-type doping of the graphene. These modifications introduced the structural disorder and defects on the graphene surface and resulted in a large chemical mechanism-based signal enhancement from Raman dye molecules [rhodamine B (RhB), rhodamine 6G (R6G), and crystal violet (CV) in this case] on graphene. Importantly, the enhancement factors were increased from ∼10(3) before ozone treatment to ∼10(4), which is the largest chemical enhancement factor ever on graphene, after 5 min ozone treatment due to both high oxidation and p-doping effects on graphene surface. Over a centimeter-scale area of this UV/ozone-oxidized graphene substrate, strong SERS signals were repeatedly and reproducibly detected. In a UV/ozone-based micropattern, UV/ozone-treated areas were highly Raman-active while nontreated areas displayed very weak Raman signals.

  9. Strain Compatible Oxidation and Corrosion Protection Coatings for Enhanced Thermo-Mechanical Durability of Turbine Airfoils

    DTIC Science & Technology

    2011-12-05

    Report: Grant N00014-08-0331 Technical Objectives As critical components of advanced aircraft engines , turbine airfoils require coatings for...advanced aircrafi engines , turbine airfoils require coatings for enhancement of oxidation, corrosion and thermal capabilities . Airfoil coatings ofien...Oxidation and Corrosion Protection Coatings for Enhanced Thermo-Mechanical Durability of Turbine Airfoils 5b. GRANT NUMBER N00014-08-l-0331 5c

  10. Observations and Model Analysis of Enhanced Oxidized Mercury in the Free Troposphere during NOMADSS

    NASA Astrophysics Data System (ADS)

    Gratz, L.; Shah, V.; Ambrose, J. L., II; Jaffe, D. A.; Jaegle, L.; Selin, N. E.; Song, S.; Festa, J.; Stutz, J.

    2014-12-01

    Mercury (Hg) is a hazardous neurotoxic pollutant with complex atmospheric speciation and chemistry. It exists in the atmosphere primarily as gaseous elemental Hg (GEM), with a lifetime on the order of months, while oxidized Hg is more water soluble and deposits readily. Thus, Hg is considered both a local and a global pollutant. There are significant limitations in our understanding of global Hg cycling, including the sources and chemical mechanisms producing enhanced oxidized Hg in the free troposphere. Ground-based and airborne studies have associated free tropospheric oxidized Hg with GEM oxidation and atmospheric subsidence. Chemical transport models suggest that free tropospheric GEM oxidation is largely attributable to bromine (Br) atoms. During the 2013 Nitrogen Oxidants Mercury and Aerosol Distributions Sources and Sinks (NOMADSS) campaign, we sought to quantify the distribution and chemical transformation of Hg species in the free troposphere over the southeastern US. Enhanced oxidized Hg over North Texas was associated with long-range transport and subsidence from the sub-tropical Pacific free troposphere, where GEOS-Chem predicts air enriched in oxidized Hg. Bromine oxide (BrO) concentrations were also elevated over North Texas, perhaps supporting halogen oxidation as a source of free tropospheric oxidized Hg. Over the Atlantic Ocean, oxidized Hg up to 680 pg m-3 was associated with GEM oxidation and subsidence within the Atlantic high pressure system. The standard GEOS-Chem model underestimates free tropospheric oxidized Hg in these locations by a factor of three to ten, possibly due to underestimation of Br concentrations and/or uncertainty in the Hg+Br rate constant. We investigate GEOS-Chem's improved ability to reproduce the observed concentrations by tripling free tropospheric Br in the tropics and implementing a faster Hg+Br oxidation mechanism. Results have important implications for our understanding of global-scale atmospheric Hg chemistry and

  11. Catalyst Additives to Enhance Mercury Oxidation and Capture

    SciTech Connect

    Alex J. Berry; Thomas K. Gale

    2005-09-30

    Preliminary research has shown that SCR catalysts employed for nitrogen-oxide reduction can effectively oxidize mercury. This report discusses initial results from fundamental investigations into the behavior of mercury species in the presence of SCR catalysts at Southern Research Institute. The testing was performed at Southern Research's Catalyst Test Facility, a bench-scale reactor capable of simulating gas-phase reactions occurring in coal-fired utility pollution-control equipment. Three different SCR catalysts are currently being studied in this project - honeycomb-type, plate-type, and a hybrid-type catalyst. The catalysts were manufactured and supplied by Cormetech Inc., Hitachi America Ltd., and Haldor-Topsoe Inc., respectively. Parametric testing was performed to investigate the contribution of flue-gas chemistry on mercury oxidation via SCR catalysts. Methods and procedures for experimental testing continue to be developed to produce the highest quality mercury-oxidation data. Most experiments so far have focused on testing the catalysts in a simulated Powder River Basin (PRB) flue-gas environment, which contains lower sulfur and chlorine than produced by other coals. Future work to characterize flue gas simulations typically derived from low and high sulfur bituminous coal will be performed in a stepwise manner, to avoid the constant interruptions in testing that occur when leaks in the system are generated during temperature transitions. Specifically, chlorine concentration vs. mercury oxidation graph will be developed for each catalyst. The contributions of temperature and later sulfur will be investigated after this is complete. Also, last quarter's tests showed a potential linear relationship between SO3 conversion and mercury oxidation. As a result, SO3 samples will be taken more frequently to investigate each catalyst's ability to selectively oxidize mercury.

  12. Insulin-like growth factor I stimulates lipid oxidation, reduces protein oxidation, and enhances insulin sensitivity in humans.

    PubMed Central

    Hussain, M A; Schmitz, O; Mengel, A; Keller, A; Christiansen, J S; Zapf, J; Froesch, E R

    1993-01-01

    To elucidate the effects of insulin-like growth factor I (IGF-I) on fuel oxidation and insulin sensitivity, eight healthy subjects were treated with saline and recombinant human (IGF-I (10 micrograms/kg.h) during 5 d in a crossover, randomized fashion, while receiving an isocaloric diet (30 kcal/kg.d) throughout the study period. On the third and fourth treatment days, respectively, an L-arginine stimulation test and an intravenous glucose tolerance test were performed. A euglycemic, hyperinsulinemic clamp combined with indirect calorimetry and a glucose tracer infusion were performed on the fifth treatment day. IGF-I treatment led to reduced fasting and stimulated (glucose and/or L-arginine) insulin and growth hormone secretion. Basal and stimulated glucagon secretion remained unchanged. Intravenous glucose tolerance was unaltered despite reduced insulin secretion. Resting energy expenditure and lipid oxidation were both elevated, while protein oxidation was reduced, and glucose turnover rates were unaltered on the fifth treatment day with IGF-I as compared to the control period. Enhanced lipolysis was reflected by elevated circulating free fatty acids. Moreover, insulin-stimulated oxidative and nonoxidative glucose disposal (i.e., insulin sensitivity) were enhanced during IGF-I treatment. Thus, IGF-I treatment leads to marked changes in lipid and protein oxidation, whereas, at the dose used, carbohydrate metabolism remains unaltered in the face of reduced insulin levels and enhanced insulin sensitivity. Images PMID:8227340

  13. A novel system of galangin-potassium permanganate-polyphosphoric acid for the determination of tryptophan and its chemiluminescence mechanism.

    PubMed

    Li, Li; Guo, Ruibin; Zhang, Dongxia; Du, Xinzhen

    2015-08-01

    A novel galangin-potassium permanganate (KMnO4)-polyphosphoric acid (PPA) system was found to have an outstanding response to tryptophan (Trp). Trp determination using this KMnO4 -PPA system was enhanced significantly in the presence of galangin. A highly sensitive flow-injection chemiluminescence (CL) method to determine Trp was developed based on the CL reaction of galangin-KMnO4 -Trp in PPA media. The presence of galangin, a member of the flavonol class of flavonoid complexes, greatly increased the luminous intensity of Trp in KMnO4 -PPA systems. Under optimized conditions, Trp was determined in the 0.05-10 µg/mL range, with a detection limit (3σ) of 5.0 × 10(-3)  µg/mL. The relative standard deviation (RSD) was 1.0% for 11 replicate determinations of 1.0 µg/mL Trp. Two synthetic samples were determined selectively with recoveries of 98.4-100.1% in the presence of other amino acids. The possible mechanism is summarized as follows: excited states of Mn(II)(*) and Mn(III(*) types are the main means of generating chemical luminescent species, and Trp concentration and luminescence intensity have a linear relationship, which enables quantitative analysis.

  14. Performance of green waste biocovers for enhancing methane oxidation.

    PubMed

    Mei, Changgen; Yazdani, Ramin; Han, Byunghyun; Mostafid, M Erfan; Chanton, Jeff; VanderGheynst, Jean; Imhoff, Paul

    2015-05-01

    Green waste aged 2 and 24months, labeled "fresh" and "aged" green waste, respectively, were placed in biocover test cells and evaluated for their ability to oxidize methane (CH4) under high landfill gas loading over a 15-month testing period. These materials are less costly to produce than green waste compost, yet satisfied recommended respiration requirements for landfill compost covers. In field tests employing a novel gas tracer to correct for leakage, both green wastes oxidized CH4 at high rates during the first few months of operation - 140 and 200g/m(2)/day for aged and fresh green waste, respectively. Biocover performance degraded during the winter and spring, with significant CH4 generated from anaerobic regions in the 60-80cm thick biocovers. Concurrently, CH4 oxidation rates decreased. Two previously developed empirical models for moisture and temperature dependency of CH4 oxidation in soils were used to test their applicability to green waste. Models accounted for 68% and 79% of the observed seasonal variations in CH4 oxidation rates for aged green waste. Neither model could describe similar seasonal changes for the less stable fresh green waste. This is the first field application and evaluation of these empirical models using media with high organic matter. Given the difficulty of preventing undesired CH4 generation, green waste may not be a viable biocover material for many climates and landfill conditions.

  15. Correction: Enhanced photoelectrochemical water oxidation via atomic layer deposition of TiO2 on fluorine-doped tin oxide nanoparticle films

    NASA Astrophysics Data System (ADS)

    Cordova, Isvar A.; Peng, Qing; Ferrall, Isa L.; Rieth, Adam J.; Hoertz, Paul G.; Glass, Jeffrey T.

    2015-07-01

    Correction for `Enhanced photoelectrochemical water oxidation via atomic layer deposition of TiO2 on fluorine-doped tin oxide nanoparticle films' by Isvar A. Cordova, et al., Nanoscale, 2015, 7, 8584-8592.

  16. Correction: Enhanced photoelectrochemical water oxidation via atomic layer deposition of TiO2 on fluorine-doped tin oxide nanoparticle films.

    PubMed

    Cordova, Isvar A; Peng, Qing; Ferrall, Isa L; Rieth, Adam J; Hoertz, Paul G; Glass, Jeffrey T

    2015-07-28

    Correction for 'Enhanced photoelectrochemical water oxidation via atomic layer deposition of TiO2 on fluorine-doped tin oxide nanoparticle films' by Isvar A. Cordova, et al., Nanoscale, 2015, 7, 8584-8592.

  17. Enhanced Formation of Oxidants from Bimetallic Nickel-Iron Nanoparticles in the Presence of Oxygen

    PubMed Central

    Lee, Changha; Sedlak, David L.

    2009-01-01

    Nanoparticulate zero-valent iron (nZVI) rapidly reacts with oxygen to produce strong oxidants, capable of transforming organic contaminants in water. However, the low yield of oxidants with respect to the iron added normally limits the application of this system. Bimetallic nickel-iron nanoparticles (nNi-Fe; i.e., Ni-Fe alloy and Ni-coated Fe nanoparticles) exhibited enhanced yields of oxidants compared to nZVI. nNi-Fe (Ni-Fe alloy nanoparticles with [Ni]/[Fe] = 0.28 and Ni-coated Fe nanoparticles with [Ni]/[Fe] = 0.035) produced approximately 40% and 85% higher yields of formaldehyde from the oxidation of methanol relative to nZVI at pH 4 and 7, respectively. Ni-coated Fe nanoparticles showed a higher efficiency for oxidant production relative to Ni-Fe alloy nanoparticles based on Ni content. Addition of Ni did not enhance the oxidation of 2-propanol or benzoic acid, indicating that Ni addition did not enhance hydroxyl radical formation. The enhancement in oxidant yield was observed over a pH range of 4 – 9. The enhanced production of oxidant by nNi-Fe appears to be attributable to two factors. First, the nNi-Fe surface is less reactive toward hydrogen peroxide (H2O2) than the nZVI surface, which favors the reaction of H2O2 with dissolved Fe(II) (the Fenton reaction). Second, the nNi-Fe surface promotes oxidant production from the oxidation of ferrous ion by oxygen at neutral pH values. PMID:19068843

  18. Bioremediation enhancement of phenanthrene contaminated soils by chemical pre-oxidation

    SciTech Connect

    Van Kemenade, I.; Anderson, W.A.; Scharer, J.M.; Moo-Young, Murray

    1995-12-31

    A two-step oxidation process was investigated for the treatment of phenanthrene contaminated soil fines (particle diameter {le}63 {mu}m) resulting from a soil washing process. Oxone{reg_sign} (2KHSO{sub 5}{center_dot}KHSO{sub 4}{center_dot}K{sub 2}SO{sub 4}) and hydrogen peroxide (H{sub 2}O{sub 2}) were used as oxidants for the chemical pre-oxidation step and unacclimatized municipal activated sludge was employed in the subsequent biodegradation step. Oxone was found to have an oxidation efficiency approximately ten-fold greater than hydrogen peroxide on a stoichiometric basis. In comparison to chemical oxidation only, a 24 hour pre-oxidation step using 5 and 10 g/L Oxone followed by a 5 day biological oxidation step enhanced removal of phenanthrene from the soil by 115% and 32%, respectively. Similarly, a 48 hour pre-oxidation step utilizing 5 and 10 g/L Oxone followed by a 5 day biological oxidation step enhanced the removal of phenanthrene from the soil by 113% and 43%, respectively. Based on this preliminary assessment, a treatment protocol that integrates a 24 hour chemical preoxidation step with 5 g/L Oxone followed by a 5 day biological oxidation step appears to be an effective combination for the remediation of this phenanthrene contaminated soil. 21 refs., 4 figs., 2 tabs.

  19. Catalyst Additives to Enhance Mercury Oxidation and Capture

    SciTech Connect

    Jared W. Cannon; Thomas K. Gale

    2005-06-30

    Preliminary research has shown that SCR catalysts employed for nitrogen-oxide reduction can effectively oxidize mercury. This report discusses initial results from fundamental investigations into the behavior of mercury species in the presence of SCR catalysts at Southern Research Institute. The testing was performed at Southern Research's Catalyst Test Facility, a bench-scale reactor capable of simulating gas-phase reactions occurring in coal-fired utility pollution-control equipment. Three different SCR catalysts are currently being studied in this project--honeycomb-type, plate-type, and a hybrid-type catalyst. The catalysts were manufactured and supplied by Cormetech Inc., Hitachi America Ltd., and Haldor-Topsoe Inc., respectively. Parametric testing was performed to investigate the contribution of flue-gas chemistry on mercury oxidation via SCR catalysts. Methods and procedures for experimental testing continue to be developed to produce the highest quality mercury-oxidation data. During this past quarter, it was discovered that long periods (12 - 24 hours) are required to equilibrate the catalysts in the system. In addition, after the system has been equilibrated, operational changes to temperature, gas concentration, or flow rate shifts the equilibrium, and steady-state must be reestablished, which can require as much as twelve additional hours per condition change. In the last quarter of testing, it was shown that the inclusion of ammonia had a strong effect on the oxidation of mercury by SCR catalysts, both in the short-term (a transitional period of elemental and oxidized mercury off gassing) and the long-term (less steady-state mercury oxidation). All experiments so far have focused on testing the catalysts in a simulated Powder River Basin (PRB) flue-gas environment, which contains lower sulfur and chlorine than produced by other coals. In the next quarter, parametric testing will be expanded to include flue gases simulating power plants burning

  20. Development of hierarchically porous cobalt oxide for enhanced photo-oxidation of indoor pollutants

    NASA Astrophysics Data System (ADS)

    Cheng, J. P.; Shereef, Anas; Gray, Kimberly A.; Wu, Jinsong

    2015-03-01

    Porous cobalt oxide was successfully prepared by precipitation of cobalt hydroxide followed by low temperature thermal decomposition. The morphologies of the resultant oxides remained as the corresponding hydroxides, although the morphology of cobalt hydroxides was greatly influenced by the precursor salts. The cobalt oxides with average crystal size less than 20 nm were characterized by X-ray diffraction, scanning electron microscope, BET surface area, and XPS analysis. The photocatalytic activities of the various cobalt oxides morphologies were investigated by comparing the photo-degradation of acetaldehyde under simulated solar illumination. Relative to their low order structures and reference titania samples, the hierarchical nanostructures of cobalt oxide showed excellent abilities to rapidly degrade acetaldehyde, a model air pollutant. This was attributed to the unique nature of these hierarchical cobalt oxide nanoassemblies, which contained many catalytically active reaction sites and open pores.

  1. Nitrous oxide emissions with enhanced efficiency nitrogen fertilizers in rainfed system

    USDA-ARS?s Scientific Manuscript database

    The use of enhanced efficiency nitrogen (N) fertilizers can increase crop N utilization and lead to lower emissions of the greenhouse gas nitrous oxide (N2O). To determine potential benefit of four enhanced efficiency fertilizers with rain-fed corn production in central Pennsylvania, USA, N2O emissi...

  2. Control of photoinduced fluorescence enhancement of colloidal quantum dots using metal oxides

    NASA Astrophysics Data System (ADS)

    Sadeghi, Seyed M.; Wing, Waylin J.; Patty, Kira; Campbell, Quinn

    2015-10-01

    It is well known that irradiation of colloidal quantum dots can dramatically enhance their emission efficiencies, leading to so-called photoinduced fluorescence enhancement (PFE). This process is the result of the photochemical and photophysical properties of quantum dots and the way they interact with the environment in the presence of light. It has been shown that such properties can be changed significantly using metal oxides. Using spectroscopic techniques, in this paper we investigate emission of different types of quantum dots (with and without shell) in the presence of metal oxides with opposing effects. We observed significant increase of PFE when quantum dots are deposited on about one nanometer of aluminum oxide, suggesting such oxide can profoundly increase quantum yield of such quantum dots. On the other hand, copper oxide can lead to significant suppression of emission of quantum dots, making them nearly completely dark instantly.

  3. The influence of a non-aqueous phase liquid (NAPL) and chemical oxidant application on perfluoroalkyl acid (PFAA) fate and transport.

    PubMed

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

    2016-04-01

    One dimensional column experiments were conducted using saturated porous media containing residual trichloroethylene (TCE) to understand the effects of non-aqueous phase liquids (NAPLs) and chemical oxidation on perfluoroalkyl acid (PFAA) fate and transport. Observed retardation factors and data from supporting batch studies suggested that TCE provides additional sorption capacity that can increase PFAA retardation (i.e., decreased mobility), though the mechanisms remain unclear. Treatment with persulfate activated with FeCl2 and citric acid, catalyzed hydrogen peroxide (CHP), or permanganate did not result in oxidative transformations of PFAAs. However, impacts on PFAA sorption were apparent, and enhanced sorption was substantial in the persulfate-treated columns. In contrast, PFAA transport was accelerated in permanganate- and CHP-treated columns. Ultimately, PFAA transport in NAPL contaminated groundwater is likely influenced by porous media properties, NAPL characteristics, and water quality properties, each of which can change due to chemical oxidant treatment. For contaminated sites for which ISCO is a viable treatment option, changes to PFAA transport and the implications thereof should be included as a component of the remediation evaluation and selection process. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Enhanced electrochromism in cerium doped molybdenum oxide thin films

    SciTech Connect

    Dhanasankar, M.; Purushothaman, K.K.; Muralidharan, G.

    2010-12-15

    Cerium (5-15% by weight) doped molybdenum oxide thin films have been prepared on FTO coated glass substrate at 250 {sup o}C using sol-gel dip coating method. The structural and morphological changes were observed with the help of XRD, SEM and EDS analysis. The amorphous structure of the Ce doped samples, favours easy intercalation and deintercalation processes. Mo oxide films with 10 wt.% of Ce exhibit maximum anodic diffusion coefficient of 24.99 x 10{sup -11} cm{sup 2}/s and the change in optical transmittance of ({Delta}T at 550 nm) of 79.28% between coloured and bleached state with the optical density of ({Delta}OD) 1.15.

  5. Enhanced optical limiting effect in fluorine-functionalized graphene oxide

    NASA Astrophysics Data System (ADS)

    Zhang, Fang; Wang, Zhengping; Wang, Duanliang; Wang, Shenglai; Xu, Xinguang

    2017-09-01

    Nonlinear optical absorption of fluorine-functionalized graphene oxide (F-GO) solution was researched by the open-aperture Z-scan method using 1064 and 532 nm lasers as the excitation sources. The F-GO dispersion exhibited strong optical limiting property and the fitted results demonstrated that the optical limiting behavior was the result of a two-photon absorption process. For F-GO nanosheets, the two-photon absorption coefficients at 1064 nm excitation are 20% larger than the values at 532 nm excitation and four times larger than that of pure GO nanosheets. It indicates that the doping of fluorine can effectively improve the nonlinear optical property of GO especially in infrared waveband, and fluorine-functionalized graphene oxide is an excellent nonlinear absorption material in infrared waveband.

  6. Photo-oxidative enhancement of polymeric molecular sieve membranes.

    PubMed

    Song, Qilei; Cao, Shuai; Zavala-Rivera, Paul; Lu, Li Ping; Li, Wei; Ji, Yan; Al-Muhtaseb, Shaheen A; Cheetham, Anthony K; Sivaniah, Easan

    2013-01-01

    High-performance membranes are attractive for molecular-level separations in industrial-scale chemical, energy and environmental processes. The next-generation membranes for these processes are based on molecular sieving materials to simultaneously achieve high throughput and selectivity. Membranes made from polymeric molecular sieves such as polymers of intrinsic microporosity (pore size<2 nm) are especially interesting in being solution processable and highly permeable but currently have modest selectivity. Here we report photo-oxidative surface modification of membranes made of a polymer of intrinsic microporosity. The ultraviolet light field, localized to a near-surface domain, induces reactive ozone that collapses the microporous polymer framework. The rapid, near-surface densification results in asymmetric membranes with a superior selectivity in gas separation while maintaining an apparent permeability that is two orders of magnitude greater than commercially available polymeric membranes. The oxidative chain scission induced by ultraviolet irradiation also indicates the potential application of the polymer in photolithography technology.

  7. Zinc Oxide Nanowire Interphase for Enhanced Lightweight Polymer Fiber Composites

    NASA Technical Reports Server (NTRS)

    Sodano, Henry A.; Brett, Robert

    2011-01-01

    The objective of this work was to increase the interfacial strength between aramid fiber and epoxy matrix. This was achieved by functionalizing the aramid fiber followed by growth of a layer of ZnO nanowires on the fiber surface such that when embedded into the polymer, the load transfer and bonding area could be substantially enhanced. The functionalization procedure developed here created functional carboxylic acid surface groups that chemically interact with the ZnO and thus greatly enhance the strength of the interface between the fiber and the ZnO.

  8. Enhancing the oxidation resistance of copper by using sandblasted copper surfaces

    NASA Astrophysics Data System (ADS)

    Yuan, Lu; Chen, Xiaoming; Maganty, Suraj; Cho, Junghyun; Ke, Changhong; Zhou, Guangwen

    2015-12-01

    We show that sandblasting can be employed to effectively enhance the oxidation resistance of copper by suppressing the interfacial delamination between copper and its oxide by modifying the surface roughness of Cu. Increasing sandblasting treatment time from 0 to 120 s increases the surface roughness of Cu from 0.12 ± 0.003 μm to 2.89 ± 0.176 μm, which results in improved oxidation resistance of the Cu surfaces and enhances the oxide/substrate interfacial fracture energy from 0.035 J/m2 to 3.1 J/m2 determined using nanoindentation. The sandblasting treatment has no appreciable effect on the Young's moduli of the Cu oxide film, which remain nearly constant at around 36 GPa. The improved oxidation resistance is ascribed to the enhanced interfacial adhesion of the sandblasted copper owing to the concave shape of craters generated by sandblasting, which results in a net downward force from the compressive stresses in the oxide film that forces the film to adhere to the Cu substrate.

  9. Plasmonic Ag@oxide nanoprisms for enhanced performance of organic solar cells.

    PubMed

    Du, Peng; Jing, Pengtao; Li, Di; Cao, Yinghui; Liu, Zhenyu; Sun, Zaicheng

    2015-05-01

    Localized surface plasmon resonance (LSPR), light scattering, and lowering the series resistance of noble metal nanoparticles (NPs) provide positive effect on the performance of photovoltaic device. However, the exciton recombination on the noble metal NPs accompanying above influences will deteriorate the performance of device. In this report, surface-modified Ag@oxide (TiO2 or SiO2 ) nanoprisms with 1-2 nm shell thickness are developed. The thin film composed of P3HT/Ag@oxides and P3HT:PCBM/Ag@oxides is investigated by absorption, photoluminescence (PL), and transient absorption spectroscopy. The results show a significant absorption, PL enhancement, and long-lived photogenerated polaron in the P3HT/Ag@TiO2 film, indicating the increase of photogenerated exciton population by LSPR of Ag nanoprisms. In the case of P3HT/Ag nanoprisms, partial PL quench and relatively short-lived photogenerated polaron are observed. That indicates that the oxides layer can effectively avoid the exciton recombination. When the Ag@oxide nanoprisms are introduced into the active layer of P3HT:PCBM photovoltaic devices, about 31% of power conversion efficiency enhancement is obtained relative to the reference cell. All these results indicate that Ag@oxides can enhance the performance of the cell, at the same time the ultrathin oxide shell prevents from the exciton recombination.

  10. Bacterial production of organic acids enhances H2O2-dependent iodide oxidation.

    PubMed

    Li, Hsiu-Ping; Yeager, Chris M; Brinkmeyer, Robin; Zhang, Saijin; Ho, Yi-Fang; Xu, Chen; Jones, Whitney L; Schwehr, Kathleen A; Otosaka, Shigeyoshi; Roberts, Kimberly A; Kaplan, Daniel I; Santschi, Peter H

    2012-05-01

    To develop an understanding of the role that microorganisms play in the transport of (129)I in soil-water systems, bacteria isolated from subsurface sediments were assessed for iodide oxidizing activity. Spent liquid medium from 27/84 bacterial cultures enhanced iodide oxidation 2-10 fold in the presence of H(2)O(2). Organic acids secreted by the bacteria were found to enhance iodide oxidation by (1) lowering the pH of the spent medium, and (2) reacting with H(2)O(2) to form peroxy carboxylic acids, which are extremely strong oxidizing agents. H(2)O(2)-dependent iodide oxidation increased exponentially from 8.4 to 825.9 μM with decreasing pH from 9 to 4. Organic acids with ≥2 carboxy groups enhanced H(2)O(2)-dependent iodide oxidation (1.5-15-fold) as a function of increasing pH above pH 6.0, but had no effect at pH ≤ 5.0. The results indicate that as pH decreases (≤5.0), increasing H(2)O(2) hydrolysis is the driving force behind iodide oxidation. However, at pH ≥ 6.0, spontaneous decomposition of peroxy carboxylic acids, generated from H(2)O(2) and organic acids, contributes significantly to iodide oxidation. The results reveal an indirect microbial mechanism, organic acid secretion coupled to H(2)O(2) production, that could enhance iodide oxidation and organo-iodine formation in soils and sediments. © 2012 American Chemical Society

  11. Amperometric nitric oxide sensors with enhanced selectivity over carbon monoxide via platinum oxide formation under alkaline conditions.

    PubMed

    Jensen, Gary C; Zheng, Zheng; Meyerhoff, Mark E

    2013-11-05

    An improved planar amperometric nitric oxide (NO) sensor with enhanced selectivity over carbon monoxide (CO), which represents a volatile interfering species for NO sensors that has been largely overlooked until recently, is described. Formation of an oxide film on the inner platinum working electrode via anodic polarization using an inner alkaline electrolyte solution provides the basis for improved selectivity. Cyclic voltammetry reveals that formation of an oxidized Pt film inhibits adsorption of CO to the electrode surface, which is a necessary initial step in the electrocatalytic oxidation of CO on Pt. Previous NO gas sensors that employ internal electrolyte solutions have been assembled using acidic internal solutions that inhibit the formation of a dense platinum oxide film on the working electrode surface. It is demonstrated herein that increasing the internal electrolyte pH promotes oxidized platinum film formation, resulting in improved selectivity over CO. Selectivity coefficients (log KNO,j) for sensors assembled with internal solutions at various pH values range from -0.08 at pH 2.0 to -2.06 at pH 11.7, with average NO sensitivities of 1.24 nA/μM and a limit of detection (LOD) of <1 nM.

  12. Phenolic mediators enhance the manganese peroxidase catalyzed oxidation of recalcitrant lignin model compounds and synthetic lignin.

    PubMed

    Nousiainen, Paula; Kontro, Jussi; Manner, Helmiina; Hatakka, Annele; Sipilä, Jussi

    2014-11-01

    Fungal oxidative enzymes, such as peroxidases and laccases, are the key catalysts in lignin biodegradation in vivo, and consequently provide an important source for industrial ligninolytic biocatalysts. Recently, it has been shown that some syringyl-type phenolics have potential as industrial co-oxidants or mediators, in laccase-catalyzed modification of lignocellulosic material. We have now studied the effect of such mediators with ligninolytic peroxidases on oxidation of the most recalcitrant lignin model compounds. We found that they are able to enhance the manganese peroxidase (MnP) catalyzed oxidation reactions of small non-phenolic compounds, veratryl alcohol and veratrylglycerol β-guaiacyl ether (adlerol), which are not usually oxidized by manganese peroxidases alone. In these experiments we compared two peroxidases from white-rot fungi, MnP from Phlebia sp. Nf b19 and versatile peroxidase (VP) from Bjerkandera adusta under two oxidation conditions: (i) the Mn(III) initiated mediated oxidation by syringyl compounds and (ii) the system involving MnP-dependent lipid peroxidation, both with production of (hydrogen) peroxides in situ to maintain the peroxidase catalytic cycle. It was found that both peroxidases produced α-carbonyl oxidation product of veratryl alcohol in clearly higher yields in reactions mediated by phenoxy radicals than in lipid-peroxyl radical system. The oxidation of adlerol, on the other hand, was more efficient in lipid-peroxidation-system. VP was more efficient than MnP in the oxidation of veratryl alcohol and showed its lignin peroxidase type activity in the reaction conditions indicated by some cleavage of Cα-Cβ-bond of adlerol. Finally, the mediator assisted oxidation conditions were applied in the oxidation of synthetic lignin (DHP) and the structural analysis of the oxidized polymers showed clear modifications in the polymer outcome, e.g. the oxidation resulted in reduced amount of aliphatic hydroxyls indicated by (31)P NMR.

  13. Basal nitric oxide production is enhanced by hydraulic pressure in cultured human trabecular cells

    PubMed Central

    Matsuo, T.

    2000-01-01

    BACKGROUND/AIMS—Nitric oxide donors reduce intraocular pressure. Human trabecular cells in culture were examined for their nitric oxide production in response to hydraulic pressure.
METHODS—Human trabecular cells were cultured from trabeculum tissue fragments excised during trabeculectomy and exposed to hydraulic pressure change in a culture flask connected to a glass syringe. The pressure was exerted by automatic infusion of the piston of the syringe and monitored by a pressure gauge. The intracellular nitric oxide level was measured in real time with a nitric oxide binding fluorescent dye, diaminofluorescein-2.
RESULTS—Intracellular nitric oxide levels in cultured trabecular cells showed spontaneous fluctuation during 400 seconds of observation. Peak levels of intracellular nitric oxide were significantly higher at hydraulic pressure of 30, 40, and 50 mm Hg, compared with 0 and 25 mm Hg (p<0.0001, one way ANOVA, and p<0.05, Tukey-Kramer test). The fluctuation was completely abolished by the presence of N-methyl-L-arginine (L-NMMA), a nitric oxide synthase inhibitor. The cultured trabecular cells were shown by immunohistochemistry to express brain nitric oxide synthase (bNOS).
CONCLUSION—Higher levels of hydraulic pressure enhanced basal production of nitric oxide in human trabecular cells. Nitric oxide would be a physiological mediator in the regulation of intraocular pressure.

 PMID:10837391

  14. Histopathological and bacterial study of Persian sturgeon fry, Acipenser persicus (Borodin, 1897) exposed to copper sulfate and potassium permanganate.

    PubMed

    Moshtaghi, Batol; Khara, Hossein; Pazhan, Zabiyollah; Shenavar, Alireza

    2016-09-01

    Persian sturgeon frys were exposed to different concentrations of copper sulfate and potassium permanganate in order to the evaluation of their impacts on bacterial load of skin, gill and surrounding water and also the histopathological alternations of gill tissue. For this purpose, the sublethal doses were determined after a pre-test and then the experiment was done in 4 (for copper sulfate: 0.07, 0.14, 026 and 0.5 mg/l) and 5 (for potassium permanganate: 0.07, 0.14, 026, 0.5 and 1 mg/l) treatments with three replicates inside the glass aquaria. Also, one group without disinfecting drug was considered as control for each experiment. The microbial and histopathological investigations were done after 96 h exposure. According to our results, a range of histopathological alternations were observed in gills tissue including mucus coagulation and secretion, hyperplasia, lamellar necrosis, hyperplasia, lamellar adhesion, haemorrhage, thickening of secondary lamellae, hypertrophy of supporter cartilage, clubbing of gill lamellae and sliming of primary lamellae. The severity of these alternations increased with increasing of the doses of the copper sulfate and potassium permanganate. The bacterial load (CFU/g) of gill, skin and surrounding water was lower in 0.07 mg/l copper sulfate treatment and 1 mg/l potassium permanganate treatment (P < 0.05) than in other treatments. In conclusion, our results showed that the certain doses of the copper sulfate and potassium permanganate have disinfecting effects on bacterial load of gill, skin and surrounding water, although this is along with some histopathological alternations. Also, it seems that the copper sulfate has higher disinfecting power than potassium permanganate.

  15. Development of an Alternative Treatment Scheme for Sr/TRU Removal: Permanganate Treatment of AN-107 Waste

    SciTech Connect

    RT Hallen; SA Bryan; FV Hoopes

    2000-08-04

    A number of Hanford tanks received waste containing organic complexants, which increase the volubility of Sr-90 and transuranic (TRU) elements. Wastes from these tanks require additional pretreatment to remove Sr-90 and TRU for immobilization as low activity waste (Waste Envelope C). The baseline pretreatment process for Sr/TRU removal was isotopic exchange and precipitation with added strontium and iron. However, studies at both Battelle and Savannah River Technology Center (SRTC) have shown that the Sr/Fe precipitates were very difficult to filter. This was a result of the formation of poor filtering iron solids. An alternate treatment technology was needed for Sr/TRU removal. Battelle had demonstrated that permanganate treatment was effective for decontaminating waste samples from Hanford Tank SY-101 and proposed that permanganate be examined as an alternative Sr/TRU removal scheme for complexant-containing tank wastes such as AW107. Battelle conducted preliminary small-scale experiments to determine the effectiveness of permanganate treatment with AN-107 waste samples that had been archived at Battelle from earlier studies. Three series of experiments were performed to evaluate conditions that provided adequate Sr/TRU decontamination using permanganate treatment. The final series included experiments with actual AN-107 diluted feed that had been obtained specifically for BNFL process testing. Conditions that provided adequate Sr/TRU decontamination were identified. A free hydroxide concentration of 0.5M provided adequate decontamination with added Sr of 0.05M and permanganate of 0.03M for archived AN-107. The best results were obtained when reagents were added in the sequence Sr followed by permanganate with the waste at ambient temperature. The reaction conditions for Sr/TRU removal will be further evaluated with a 1-L batch of archived AN-107, which will provide a large enough volume of waste to conduct crossflow filtration studies (Hallen et al. 2000a).

  16. Modifying zirconia solid electrolyte surface property to enhance oxide transport

    SciTech Connect

    Liaw, B.Y.; Song, S.Y.

    1996-12-31

    Bismuth-strontium-calcium-copper oxide (Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}, BSCCO) is known for its high T{sub c} superconducting behavior and mixed conducting property. The applicability of similar high T{sub c} cuprates for intermediate-temperature solid oxide fuel cell (SOFC) application has been studied recently. We investigated the electrochemical behavior of several Ag{vert_bar}BSCCO{vert_bar}10 mol% yttria-stabilized zirconia (YSZ){vert_bar}Ag and Ag{vert_bar}YSZ{vert_bar}Ag cells using complex impedance spectroscopy. A highly uniform and porous microstructure was observed at the interface of the YSZ and BSCCO. The ionic conductivity determined from the Nyquest plots in the temperature range of 200-700{degrees}C agrees with the values reported in the literature. The specific resistance of the BSCCO{vert_bar}YSZ interface was also determined to be lower than those of the conventional manganite electrode, suggesting that BSCCO seems attractive for cathode applications in SOFC.

  17. Peat Land Oxidation Enhances Subsidence in the Venice Watershed

    NASA Astrophysics Data System (ADS)

    Gambolati, Giuseppe; Putti, Mario; Teatini, Pietro; Camporese, Matteo; Ferraris, Stefano; Stori, Giuseppe Gasparetto; Nicoletti, Vincenzo; Silvestri, Sonia; Rizzetto, Federica; Tosi, Luigi

    2005-06-01

    The southernmost part of the Venice Lagoon catchment was progressively reclaimed from marshland starting from the end of the 19th century and finishing in the late 1930s (Figure 1). As a major result, the area was turned into a fertile farmland. At present, the area is kept dry by a distributed drainage system that collects the water from a capillary network of ditches, and pumps it into the lagoon or the sea. By its very origin this area lies below sea level and progressively sinks mainly because of bio-oxidation of the histosols (soils with high organic content) that represent a large fraction of the outcropping soil in the area. The bio-oxidation process occurs in close connection with the agricultural practices and is currently responsible for a subsidence rate of between 1.5 and 2 cm/yr. The Venice Organic Soil Subsidence (VOSS) project was undertaken with the objective of understanding the process of land settlement in this area, quantifying past and present subsidence rates, and advancing possible remedial measures that would not penalize the current agricultural activities of the area. The study, conducted in close collaboration with the local Land Reclamation Authority (Consorzio di Bonifica) and the farmland owners, is focused on a hydrologically controlled catchment, the Zennare Basin (Venice, Italy).

  18. 1,4-Diketones from Cross-Conjugated Dienones: Potassium Permanganate-Interrupted Nazarov Reaction.

    PubMed

    Kwon, Yonghoon; Schatz, Devon J; West, Frederick G

    2015-08-17

    A domino potassium permanganate-interrupted Nazarov reaction to yield syn-2,3-disubstituted 1,4-diketones via a decarbonylative cleavage of the Nazarov oxyallyl intermediate, believed to be without precedent, is presented. This process allows syn substituents to be established stereospecifically on the 2-carbon bridge connecting the ketone carbonyl carbons, and the formation of one carbon-carbon and two carbon-oxygen bonds. Two carbon-carbon bonds are cleaved in this process. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Plasma enhanced chemical vapor deposition (PECVD) method of forming vanadium oxide films and vanadium oxide thin-films prepared thereby

    DOEpatents

    Zhang, Ji-Guang; Tracy, C. Edwin; Benson, David K.; Turner, John A.; Liu, Ping

    2000-01-01

    A method is disclosed of forming a vanadium oxide film on a substrate utilizing plasma enhanced chemical vapor deposition. The method includes positioning a substrate within a plasma reaction chamber and then forming a precursor gas comprised of a vanadium-containing chloride gas in an inert carrier gas. This precursor gas is then mixed with selected amounts of hydrogen and oxygen and directed into the reaction chamber. The amounts of precursor gas, oxygen and hydrogen are selected to optimize the final properties of the vanadium oxide film An rf plasma is generated within the reaction chamber to chemically react the precursor gas with the hydrogen and the oxygen to cause deposition of a vanadium oxide film on the substrate while the chamber deposition pressure is maintained at about one torr or less. Finally, the byproduct gases are removed from the plasma reaction chamber.

  20. Investigation on the Enhanced Oxidation of Ferritic/Martensitic Steel P92 in Pure Steam.

    PubMed

    Yuan, Juntao; Wu, Ximao; Wang, Wen; Zhu, Shenglong; Wang, Fuhui

    2014-04-03

    Oxidation of ferritic/martensitic steel P92 was investigated in pure oxygen and in pure steam at 600-800 °C by thermogravimetric analysis (TGA), optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results showed that the oxidation of P92 was significantly enhanced and multilayer scale with an outer iron oxides layer formed in pure steam. At 700 °C, the gas switch markedly influenced the scaling kinetics and scale microstructure. It was supposed that the higher affinity of iron to steam would be attributed to the enhanced oxidation of P92 in pure steam, and the much easier transport of hydroxyl would account for the significant difference induced by gas switch.

  1. Investigation on the Enhanced Oxidation of Ferritic/Martensitic Steel P92 in Pure Steam

    PubMed Central

    Yuan, Juntao; Wu, Ximao; Wang, Wen; Zhu, Shenglong; Wang, Fuhui

    2014-01-01

    Oxidation of ferritic/martensitic steel P92 was investigated in pure oxygen and in pure steam at 600–800 °C by thermogravimetric analysis (TGA), optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results showed that the oxidation of P92 was significantly enhanced and multilayer scale with an outer iron oxides layer formed in pure steam. At 700 °C, the gas switch markedly influenced the scaling kinetics and scale microstructure. It was supposed that the higher affinity of iron to steam would be attributed to the enhanced oxidation of P92 in pure steam, and the much easier transport of hydroxyl would account for the significant difference induced by gas switch. PMID:28788592

  2. Enhancement Effect of Noble Metals on Manganese Oxide for the Oxygen Evolution Reaction.

    PubMed

    Seitz, Linsey C; Hersbach, Thomas J P; Nordlund, Dennis; Jaramillo, Thomas F

    2015-10-15

    Developing improved catalysts for the oxygen evolution reaction (OER) is key to the advancement of a number of renewable energy technologies, including solar fuels production and metal air batteries. In this study, we employ electrochemical methods and synchrotron techniques to systematically investigate interactions between metal oxides and noble metals that lead to enhanced OER catalysis for water oxidation. In particular, we synthesize porous MnOx films together with nanoparticles of Au, Pd, Pt, or Ag and observe significant improvement in activity for the combined catalysts. Soft X-ray absorption spectroscopy (XAS) shows that increased activity correlates with increased Mn oxidation states to 4+ under OER conditions compared to bare MnOx, which exhibits minimal OER current and remains in a 3+ oxidation state. Thickness studies of bare MnOx films and of MnOx films deposited on Au nanoparticles reveal trends suggesting that the enhancement in activity arises from interfacial sites between Au and MnOx.

  3. Enhancing magnetoresistance in tetrathiafulvalene carboxylate modified iron oxide nanoparticle assemblies

    NASA Astrophysics Data System (ADS)

    Lv, Zhong-Peng; Luan, Zhong-Zhi; Cai, Pei-Yu; Wang, Tao; Li, Cheng-Hui; Wu, Di; Zuo, Jing-Lin; Sun, Shouheng

    2016-06-01

    We report a facile approach to stabilize Fe3O4 nanoparticles (NPs) by using tetrathiafulvalene carboxylate (TTF-COO-) and to control electron transport with an enhanced magnetoresistance (MR) effect in TTF-COO-Fe3O4 NP assemblies. This TTF-COO-coating is advantageous over other conventional organic coatings, making it possible to develop stable Fe3O4 NP arrays for sensitive spintronics applications.We report a facile approach to stabilize Fe3O4 nanoparticles (NPs) by using tetrathiafulvalene carboxylate (TTF-COO-) and to control electron transport with an enhanced magnetoresistance (MR) effect in TTF-COO-Fe3O4 NP assemblies. This TTF-COO-coating is advantageous over other conventional organic coatings, making it possible to develop stable Fe3O4 NP arrays for sensitive spintronics applications. Electronic supplementary information (ESI) available: Experimental details; supplementary figures and tables. See DOI: 10.1039/c6nr03311c

  4. Enhanced production of oxidised mercury over the tropical Pacific Ocean: a key missing oxidation pathway

    NASA Astrophysics Data System (ADS)

    Wang, F.; Saiz-Lopez, A.; Mahajan, A. S.; Gómez Martín, J. C.; Armstrong, D.; Lemes, M.; Hay, T.; Prados-Roman, C.

    2014-02-01

    Mercury is a contaminant of global concern. It is transported in the atmosphere primarily as gaseous elemental mercury, but its reactivity and deposition to the surface environment, through which it enters the aquatic food chain, is greatly enhanced following oxidation. Measurements and modelling studies of oxidised mercury in the polar to sub-tropical marine boundary layer (MBL) have suggested that photolytically produced bromine atoms are the primary oxidant of mercury. We report year-round measurements of elemental and oxidised mercury, along with ozone, halogen oxides (IO and BrO) and nitrogen oxides (NO2), in the MBL over the Galápagos Islands in the equatorial Pacific. Elemental mercury concentration remained low throughout the year, while higher than expected levels of oxidised mercury occurred around midday. Our results show that the production of oxidised mercury in the tropical MBL cannot be accounted for by bromine oxidation only, or by the inclusion of ozone and hydroxyl. As a two-step oxidation mechanism, where the HgBr intermediate is further oxidised to Hg(II), depends critically on the stability of HgBr, an additional oxidant is needed to react with HgBr to explain more than 50% of the observed oxidised mercury. Based on best available thermodynamic data, we show that atomic iodine, NO2, or HO2 could all play the potential role of the missing oxidant, though their relative importance cannot be determined explicitly at this time due to the uncertainties associated with mercury oxidation kinetics. We conclude that the key pathway that significantly enhances atmospheric mercury oxidation and deposition to the tropical oceans is missing from the current understanding of atmospheric mercury oxidation.

  5. Enhancement of convective heat transfer coefficient of ethylene glycol base cuprous oxide (Cu2O) nanofluids

    NASA Astrophysics Data System (ADS)

    Hassan, Ali; Ramzan, Naveed; Umer, Asim; Ahmad, Ayyaz; Muryam, Hina

    2017-08-01

    The enhancement in the convective heat transfer coefficient of the ethylene glycol (EG) base cuprous oxide (Cu2O) nanofluids were investigated. The nanofluids of different volume concentrations i-e 1%, 2.5% and 4.5% were prepared by the two step method. Cuprous oxide (Cu2O) nanoparticles were ultrasonically stirred for four hours in the ethylene glycol (EG). The experimental study has been performed through circular tube geometry in laminar flow regime at average Reynolds numbers 36, 71 and 116. The constant heat flux Q = 4000 (W/m2) was maintained during this work. Substantial enhancement was observed in the convective heat transfer coefficient of ethylene glycol (EG) base cuprous oxide (Cu2O) nanofluids than the base fluid. The maximum 74% enhancement was observed in convective heat transfer coefficient at 4.5 vol% concentration and Re = 116.

  6. Oxidation- and Creep-Enhanced Fatigue of Haynes 188 Alloy-Oxide Scale System Under Simulated Pulse Detonation Engine Conditions

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Fox, Dennis S.; Miller, Robert A.

    2002-01-01

    The development of the pulse detonation engine (PDE) requires robust design of the engine components that are capable of enduring harsh detonation environments. In this study, a high cycle thermal fatigue test rig was developed for evaluating candidate PDE combustor materials using a CO2 laser. The high cycle thermal fatigue behavior of Haynes 188 alloy was investigated under an enhanced pulsed laser test condition of 30 Hz cycle frequency (33 ms pulse period, and 10 ms pulse width including 0.2 ms pulse spike). The temperature swings generated by the laser pulses near the specimen surface were characterized by using one-dimensional finite difference modeling combined with experimental measurements. The temperature swings resulted in significant thermal cyclic stresses in the oxide scale/alloy system, and induced extensive surface cracking. Striations of various sizes were observed at the cracked surfaces and oxide/alloy interfaces under the cyclic stresses. The test results indicated that oxidation and creep-enhanced fatigue at the oxide scale/alloy interface was an important mechanism for the surface crack initiation and propagation under the simulated PDE condition.

  7. Enhanced flexoelectric-like response in oxide semiconductors.

    PubMed

    Narvaez, Jackeline; Vasquez-Sancho, Fabian; Catalan, Gustau

    2016-10-13

    Flexoelectricity is a property of all dielectric materials whereby they polarize in response to deformation gradients such as those produced by bending. Although it is generally thought of as a property of dielectric insulators, insulation is not a formal requirement: in principle, semiconductors can also redistribute their free charge in response to strain gradients. Here we show that bending a semiconductor not only generates a flexoelectric-like response, but that this response can in fact be much larger than in insulators. By doping single crystals of wide-bandgap oxides to increase their conductivity, their effective flexoelectric coefficient was increased by orders of magnitude. This large response can be explained by a barrier-layer mechanism that remains important even at the macroscale, where conventional (insulator) flexoelectricity otherwise tends to be small. Our results open up the possibility of using semiconductors as active ingredients in electromechanical transducer applications.

  8. Enhanced silicon oxidation on titanium-covered Si(001).

    PubMed

    Ohno, S; Shudo, K; Nakayama, F; Yamazaki, K; Ichikawa, Y; Tanaka, M; Okuda, T; Harasawa, A; Matsuda, I; Kakizaki, A

    2011-08-03

    We report on a core level photoemission study of the formation of an ultrathin SiO(x) layer grown at the interface of a titanium-covered Si(001) surface. Oxygen exposure at room temperature induces a large chemical shift of the Si 2p state, predominantly assigned to Si(4+). The results indicate that a SiO(2 - δ) layer, close to the stoichiometry of SiO(2), is formed below the TiO(x) film. The thickness of the SiO(2 - δ) layer is estimated to be ∼ 0.9 nm, corresponding to three to four oxide layers. Further chemical shift caused by annealing is attributed to the formation of titanium silicate (TiSi(x)O(y)).

  9. Enhanced photocatalytic activity of electrochemically synthesized aluminum oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Pathania, Deepak; Katwal, Rishu; Kaur, Harpreet

    2016-03-01

    In this study, aluminum oxide (Al2O3) nanoparticles (NPs) were synthesized via an electrochemical method. The effects of reaction parameters such as supporting electrolytes, solvent, current and electrolysis time on the shape and size of the resulting NPs were investigated. The Al2O3 NPs were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, thermogravimetric analysis/differential thermal analysis, energy-dispersive X-ray analysis, and ultraviolet-visible spectroscopy. Moreover, the Al2O3 NPs were explored for photocatalytic degradation of malachite green (MG) dye under sunlight irradiation via two processes: adsorption followed by photocatalysis; coupled adsorption and photocatalysis. The coupled process exhibited a higher photodegradation efficiency (45%) compared to adsorption followed by photocatalysis (32%). The obtained kinetic data was well fitted using a pseudo-first-order model for MG degradation.

  10. Inhibition of plasmonically enhanced interdot energy transfer in quantum dot solids via photo-oxidation

    SciTech Connect

    Sadeghi, S. M.; Nejat, A.; West, R. G.

    2012-11-15

    We studied the impact of photophysical and photochemical processes on the interdot Forster energy transfer in monodisperse CdSe/ZnS quantum dot solids. For this, we investigated emission spectra of CdSe/ZnS quantum dot solids in the vicinity of gold metallic nanoparticles coated with chromium oxide. The metallic nanoparticles were used to enhance the rate of the energy transfer between the quantum dots, while the chromium oxide coating led to significant increase of their photo-oxidation rates. Our results showed that irradiation of such solids with a laser beam can lead to unique spectral changes, including narrowing and blue shift. We investigate these effects in terms of inhibition of the plasmonically enhanced interdot energy transfer between quantum dots via the chromium-oxide accelerated photo-oxidation process. We demonstrate this considering energy-dependent rate of the interdot energy transfer process, plasmonic effects, and the way photo-oxidation enhances non-radiative decay rates of quantum dots with different sizes.

  11. Evaluating the effectiveness of copper sulphate, chlorine, potassium permanganate, hydrogen peroxide and ozone on cyanobacterial cell integrity.

    PubMed

    Fan, Jiajia; Ho, Lionel; Hobson, Peter; Brookes, Justin

    2013-09-15

    Cyanobacterial blooms are continuously critical challenges in drinking water systems which can have various negative impacts such as production of taste, odour and toxic compounds. Furthermore, the intracellular metabolites could be released into surrounding waters when the cyanobacterial membranes are destroyed. Although a variety of techniques have been developed to control cyanobacterial blooms and remove cyanobacterial cells or metabolites in water treatment processes, the effect of these treatments on the membrane integrity of cyanobacterial cells have not been systematically studied and compared. This study evaluated the effectiveness of copper sulphate (CuSO4), chlorine, potassium permanganate (KMnO4), hydrogen peroxide (H2O2) and ozone on the cell integrity and densities of Microcystis aeruginosa. All of these technologies can compromise the cell membrane of cyanobacteria to varying degrees. Chlorine showed the strongest ability to impair the cell integrity with a majority (≥ 88%) of the cells compromised within the first minute and with the cell lysis rates ranging of 0.640-3.82 h(-1) during 1-60 min. Ozone dose of 6 mg L(-1) also could induce 90% lysis of the cyanobacterial cells in 5 min and the cell lysis rate of KMnO4 (10 mg L(-1)) was 0.829 h(-1). CuSO4 and H2O2 could not only destroy the viability of cyanobacterial cells but also showed algistatic potential over the 7 day treatment. The potential of all the oxidants (chlorine, KMnO4, H2O2 and ozone) considered as algicides were discussed in this study. The benefits and drawbacks of these control and water treatment options were assessed as well.

  12. Enhanced oxidative vaporization of Cr2O3 and chromium by oxygen atoms

    NASA Technical Reports Server (NTRS)

    Fryburg, G. C.; Kohl, F. J.; Stearns, C. A.

    1974-01-01

    Rates of oxidative vaporization of Cr2O3 have been found to be markedly enhanced in the presence of oxygen atoms. Investigations were conducted over the temperature range 200-1250 C. For Cr2O3 the enhancement was about 10 to the 9th power at 550 C in oxygen containing 2.5% atoms. Rapid oxidative vaporization of bare chromium was observed below 800 C, the rate being about one-half that of Cr2O3. Results are interpreted in terms of thermochemical analysis.

  13. Enhanced Luminescence in Epitaxial Oxide Thin-Film Phosphors

    SciTech Connect

    Lee, Y.E.; Norton, D.P.; Budai, J.D.; Park, C.; Kim, M.; Pennycook, S.J.; Rack, P.D.; Potter, M.D.

    1999-11-08

    Undoped and Mn-doped ZnGa{sub 2}O{sub 4} thin-film phosphors were grown using pulsed laser ablation on (100) MgO single crystal and glass substrates. X-ray results showed the films on (100) MgO are well aligned both out-of plane and in-plane. Epitaxial films show superior photoluminescent intensity as compared to randomly oriented polycrystalline films, indicating that intragranular crystallinity strongIy influences luminescent properties. Li-doped ZnGa{sub 2}O{sub 4} exhibited significantly enhanced photoluminescence intensity.

  14. Enhancement of Catalytic Activity of Reduced Graphene Oxide Via Transition Metal Doping Strategy

    NASA Astrophysics Data System (ADS)

    Lee, Hangil; Hong, Jung A.

    2017-06-01

    To compare the catalytic oxidation activities of reduced graphene oxide (rGO) and rGO samples doped with five different transition metals (TM-rGO), we determine their effects on the oxidation of L-cysteine (Cys) in aqueous solution by performing electrochemistry (EC) measurements and on the photocatalytic oxidation of Cys by using high-resolution photoemission spectroscopy (HRPES) under UV illumination. Our results show that Cr-, Fe-, and Co-doped rGO with 3+ charge states (stable oxide forms: Cr3+, Fe3+, and Co3+) exhibit enhanced catalytic activities that are due to the charge states of the doped metal ions as we compare them with Cr-, Fe-, and Co-doped rGO with 2+ charge states.

  15. Aluminum and copper in drinking water enhance inflammatory or oxidative events specifically in the brain.

    PubMed

    Becaria, Angelica; Lahiri, Debomoy K; Bondy, Stephen C; Chen, DeMao; Hamadeh, Ali; Li, Huihui; Taylor, Russell; Campbell, Arezoo

    2006-07-01

    Inflammatory and oxidative events are up-regulated in the brain of AD patients. It has been reported that in animal models of AD, exposure to aluminum (Al) or copper (Cu) enhanced oxidative events and accumulation of amyloid beta (Abeta) peptides. The present study was designed to evaluate the effect of a 3-month exposure of mice to copper sulfate (8 microM), aluminum lactate (10 or 100 microM), or a combination of the salts. Results suggest that although Al or Cu may independently initiate inflammatory or oxidative events, they may function cooperatively to increase APP levels.

  16. Membrane electro-oxidizer: A new hybrid membrane system with electrochemical oxidation for enhanced organics and fouling control.

    PubMed

    Mameda, Naresh; Park, Hyung-June; Choo, Kwang-Ho

    2017-09-05

    The synergistic combination of membrane filtration with advanced oxidation is of particular interest for next-generation wastewater treatment technologies. A membrane electro-oxidizer (MEO) hybridizing a submerged microfilter and an electrochemical cell was developed and investigated for tertiary treatment of secondary industrial (textile) wastewater effluent. Laboratory- and pilot-scale MEO systems were designed and evaluated for treatment efficiency and membrane fouling control. The MEO achieved substantial removal of color (50-90%), turbidity (>90%), and bacteria (>4 log) as well as chemical oxygen demand (13-31%) and 1,4-dioxane (∼25-53%). Fluorescence-based parallel factor analysis disclosed the degradation of humic-like organics with fluorophores. Size exclusion chromatograms with organic carbon detection confirmed the removal of specific organic molecules with ∼100 Da. While investigating the effects of oxidant quenching agents, reactive chlorine species and hydrogen peroxide were found to be most responsible for the anodic oxidation of secondary effluent organics. The efficacy of membrane fouling mitigation by the MEO was greater when higher electric current densities were applied, but was not dependent on the number of electrochemical cells installed. The MEO is a promising technology for enhanced organics removal with simultaneous fouling control due to its multifunctional active oxidants. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Enhanced thermal oxidation stability of reduced graphene oxide by nitrogen doping.

    PubMed

    Sandoval, Stefania; Kumar, Nitesh; Sundaresan, A; Rao, C N R; Fuertes, Amparo; Tobias, Gerard

    2014-09-15

    Nitrogen-doped reduced graphene oxide (N-doped RGO) samples with a high level of doping, up to 13 wt. %, have been prepared by annealing graphene oxide under a flow of pure ammonia. The presence of nitrogen within the structure of RGO induces a remarkable increase in the thermal stability against oxidation by air. The thermal stability is closely related with the temperature of synthesis and the nitrogen content. The combustion reaction of nitrogen in different coordination environments (pyridinic, pyrrolic, and graphitic) is analyzed against a graphene fragment (undoped) from a thermodynamic point of view. In agreement with the experimental observations, the combustion of undoped graphene turns out to be more spontaneous than when nitrogen atoms are present.

  18. In situ oxidation and associated mass-flux-reduction/mass-removal behavior for systems with organic liquid located in lower-permeability sediments.

    PubMed

    Marble, Justin C; Carroll, Kenneth C; Janousek, Hilary; Brusseau, Mark L

    2010-09-20

    The effectiveness of permanganate for in situ chemical oxidation of organic liquid (trichloroethene) trapped in lower-permeability (K) zones located within a higher-permeability matrix was examined in a series of flow-cell experiments. The permanganate solution was applied in both continuous and pulsed-injection modes. Manganese-oxide precipitation, as confirmed by use of SEM-EDS, occurred within, adjacent to, and downgradient of the lower-K zones, reflective of trichloroethene oxidation. During flow interruptions, precipitate formed within the surrounding higher-permeability matrix, indicating diffusive flux of aqueous-phase trichloroethene from the lower-K zones. The impact of permanganate treatment on mass flux behavior was examined by conducting water floods after permanganate injection. The results were compared to those of water-flood control experiments. The amount of water flushing required for complete contaminant mass removal was reduced for all permanganate treatments for which complete removal was characterized. However, the nature of the mass-flux-reduction/mass-removal relationship observed during water flooding varied as a function of the specific permanganate treatment.

  19. In Situ Oxidation and Associated Mass-Flux-Reduction/Mass-Removal Behavior for Systems with Organic Liquid Located in Lower-Permeability Sediments

    SciTech Connect

    Marble, justin C.; Carroll, Kenneth C.; Janousek, Hilary; Brusseau, M. L.

    2010-07-21

    The effectiveness of permanganate for in situ chemical oxidation of organic liquid (trichloroethene) trapped in lower-permeability (K) zones located within a higher-permeability matrix was examined in a series of flow-cell experiments. The permanganate solution was applied in both continuous and pulsed-injection modes. Manganese-oxide precipitation, as confirmed by use of SEM-EDS, occurred within, adjacent to, and downgradient of the lower-K zones, reflective of trichloroethene oxidation. During flow interruptions, precipitate formed within the surrounding higher-permeability matrix, indicating diffusive flux of aqueous-phase trichloroethene from the lower-K zones. The impact of permanganate treatment on mass flux behavior was examined by conducting water floods after permanganate injection. The results were compared to those of water-flood control experiments. The amount of water flushing required for complete contaminant mass removal was reduced for all permanganate treatments for which complete removal was characterized. However, the nature of the mass-flux-reduction/mass-removal relationship observed during water flooding varied as a function of the specific permanganate treatment.

  20. Metal oxide surfaces for enhanced colorimetric response in bioassays.

    PubMed

    Bonyi, Enock; Kukoyi, Zeenat; Daodu, Oluseyi; Boone-Kukoyi, Zainab; Coskun, Sahin; Unalan, Husnu Emrah; Aslan, Kadir

    2017-06-01

    Physical stability of metal nanoparticle films on planar surfaces can be increased by employing surface modification techniques and/or type of metal nanoparticles. Subsequently, the enzymatic response of colorimetric bioassays can be increased for improved dynamic range for the detection of biomolecules. Using a model bioassay b-BSA, three planar platforms (1) poly (methyl methacrylate) (PMMA) with silver thin films (STFs), (2) silver nanowires (Ag NWs) on paper and (3) indium tin oxide (ITO) on polyethylene terephthalate (PET) were evaluated to investigate the extent of increase in the colorimetric signal. Bioassays for b-BSA and Ki-67 antigen (a real-life bioassay) in buffer were performed using microwave heating (total assay time is 25-30min) and at room temperature (a control experiment, total assay time is 3h). Model bioassays showed that STFs were removed from the surface during washing steps and the extent of ITO remained unchanged. The lowest level of detection (LLOD) for b-BSA bioassays were: 10(-10)M for 10nm STFs on PMMA and Ag NWs on paper and 10(-11)M for ITO. Bioassays for Ki-67 antigen yielded a LLOD of <10(-9)M on ITO platforms, while STFs platforms were deemed unusable due to significant loss of STFs from the surfaces. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Catalyst Additives to Enhance Mercury Oxidation and Capture

    SciTech Connect

    Thomas K. Gale

    2004-09-30

    Bench-scale carbon-catalyst tests were conducted in the first quarter of 2004, to obtain kinetic rates of mercury oxidation and sorption for different forms of carbon. The current quarterly report provides a more extensive quantitative analysis of the data obtained from the CRTF experiments on different carbon types and carbocalcium mixtures than was presented in the last quarterly report. The procedure and basis for normalizing mercury removals, so that they could be compared on an equal residence time basis, is described. The chemisorption rate of mercury on carbon was found to be first order in mercury concentration and half order in HCl concentration, for the facility configuration investigated. The applicable temperature range of the kinetic rates obtained is from 300 F to 700 F, and the applicable chlorine concentration range is from 2 ppmv HCl to 250 ppmv HCl. The gas-sorbent contact time of 0.12 seconds used in this work was shown to be representative of gas-dust cake contact times in full-scale baghouses. All carbon types investigated behaved similarly with respect to Hg sorption, including the effect of temperature and chlorine concentration. Activated carbon was more effective at sorbing mercury than carbon black and unburned carbon (UBC), because the internal surface area of activated carbon is greater. The synergistic relationship between Ca and C is also discussed in the report.

  2. Permanganate Treatment of DNAPLs in Reactive Barriers and Source Zone Flooding Schemes - Final Report

    SciTech Connect

    Schwartz, F.W.

    2000-10-01

    This study provides a detailed process-level understanding of the oxidative destruction of the organic contaminant emphasizing on reaction pathways and kinetics. A remarkable rise in the MnO{sup {minus}} consumption rate with TCA and PCE mixtures proves that the phase transfer catalysts have the ability to increase oxidation rate of DNAPLs either in pure phase or mixtures and that there is significant potential for testing the catalyzed scheme under field conditions. Secondly, as an attempt to enhance the oxidation of DNAPL, we are trying to exploit cosolvency effects, utilizing various alcohol-water mixtures to increase DNAPL solubilization. Preliminary results of cosolvency experiments indicate the enhancement in the transfer of nonaqueous phase TCE to TBA-water solution and the rate of TCE degradation in aqueous phase.

  3. Fenton's oxidation process for phenolic wastewater remediation and biodegradability enhancement.

    PubMed

    Martins, Rui C; Rossi, André F; Quinta-Ferreira, Rosa M

    2010-08-15

    A mixture of six phenolic acids, corresponding to an initial TOC of 370 mgC/L, was studied by Fenton's peroxidation aiming to improve the biodegradability of agro-industrial wastewaters. Input operating variables including the concentration of pollutants, iron and hydrogen peroxide as well as the reaction time were used to assess the mineralization degree through a factorial experimental methodology. A TOC removal in the range of 15.0-58.8% was attained within the operational conditions used. A reduced model was achieved using the statistically important independent factors and interactions to predict TOC degradation. On the hydrogen peroxide injection methodology, the results showed that the continuous introduction of small volumes is advantageous when compared with one single addition of the overall volume at the zero reaction time with a mineralization improvement of 11%. The use of FeSO(4).7H(2)O correspondent to a Fe(2+) load of 271 mg; [H(2)O(2)]=488.0 mM, injected in twelve aliquots each 30 min during 6h of reaction reached optimal efficiencies with the parent compounds (quantified by HPLC and the Folin-Ciocalteau method) quickly totally removed and TOC, COD and BOD(5) final values of 123 mgC/L, 180 mgO(2)/L and 146 mgO(2)/L, respectively. Toxicity assessment by Vibrio fischeri light inhibition revealed that Fenton's process reduces the effluent ecological impact related with the decomposition of the toxic phenolic acids. Indeed, EC(50) changed from 32.2% dilution to no-dilution needed. The analysis of BOD(5)/COD ratio pointed out a high improvement of the treated wastewater biodegradability from 0.30 to 0.80 meaning that the application of Fenton's oxidation as a pre-treatment enables a further application of an efficient post-biological technology which was also confirmed by respirometry.

  4. Phosphate-enhanced cytotoxicity of zinc oxide nanoparticles and agglomerates.

    PubMed

    Everett, W Neil; Chern, Christina; Sun, Dazhi; McMahon, Rebecca E; Zhang, Xi; Chen, Wei-Jung A; Hahn, Mariah S; Sue, H-J

    2014-02-10

    Zinc oxide (ZnO) nanoparticles (NPs) have been found to readily react with phosphate ions to form zinc phosphate (Zn3(PO4)2) crystallites. Because phosphates are ubiquitous in physiological fluids as well as waste water streams, it is important to examine the potential effects that the formation of Zn3(PO4)2 crystallites may have on cell viability. Thus, the cytotoxic response of NIH/3T3 fibroblast cells was assessed following 24h of exposure to ZnO NPs suspended in media with and without the standard phosphate salt supplement. Both particle dosage and size have been shown to impact the cytotoxic effects of ZnO NPs, so doses ranging from 5 to 50 μg/mL were examined and agglomerate size effects were investigated by using the bioinert amphiphilic polymer polyvinylpyrrolidone (PVP) to generate water-soluble ZnO ranging from individually dispersed 4 nm NPs up to micron-sized agglomerates. Cell metabolic activity measures indicated that the presence of phosphate in the suspension media can led to significantly reduced cell viability at all agglomerate sizes and at lower ZnO dosages. In addition, a reduction in cell viability was observed when agglomerate size was decreased, but only in the phosphate-containing media. These metabolic activity results were reflected in separate measures of cell death via the lactate dehydrogenase assay. Our results suggest that, while higher doses of water-soluble ZnO NPs are cytotoxic, the presence of phosphates in the surrounding fluid can lead to significantly elevated levels of cell death at lower ZnO NP doses. Moreover, the extent of this death can potentially be modulated or offset by tuning the agglomerate size. These findings underscore the importance of understanding how nanoscale materials can interact with the components of surrounding fluids so that potential adverse effects of such interactions can be controlled. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  5. Evolution of nanostructure, defect-free photoluminescence and enhanced photoconductivity of oxidized Zn films

    NASA Astrophysics Data System (ADS)

    Koshy, Obey; Khadar, M. Abdul

    2011-06-01

    Nanostructured zinc oxide thin films were prepared by the oxidation of nanostructured zinc films deposited on glass substrates by thermal evaporation of metallic zinc in an atmosphere of nitrogen. The films were oxidized at different temperatures. X-ray diffraction was used to study the structural transformations of the films with oxidation temperature. Atomic force microscopy images of surface morphology of the films revealed the kinetics of aggregation of the grains as the oxidation temperature was increased. Raman spectra of the samples contained a surface mode at ˜482 cm-1 showing characteristics of fine grain size. UV-Visible absorption spectra of the samples showed a blueshift of bandgap in comparison with that of bulk ZnO crystals. The photoluminescence emission spectra of the samples were free from defect related emissions. The increase in oxidation temperature of these samples caused a narrowing of the photoluminescent emission band in the UV region and an increase in the UV photocurrent. The ratio of maximum photocurrent to dark current was found to increase from 100 to 2000 as the oxidation temperature of the films increased from 350 to 500 showing an enhanced photoconductivity. The increased photocurrent was attributed to the interconnected grain structure of the ZnO samples oxidized at higher temperature.

  6. Enhanced transparent conducting networks on plastic substrates modified with highly oxidized graphene oxide nanosheets

    NASA Astrophysics Data System (ADS)

    Woo, Jong Seok; Sin, Dong Hun; Kim, Haena; Jang, Jeong In; Kim, Ho Young; Lee, Geon-Woong; Cho, Kilwon; Park, Soo-Young; Han, Joong Tark

    2016-03-01

    Atomically thin and two-dimensional graphene oxide (GO) is a very fascinating material because of its functional groups, high transparency, and solution processability. Here we show that highly oxidized GO (HOGO) nanosheets serve as an effective interfacial modifier of transparent conducting films with one-dimensional (1D) silver nanowires (AgNWs) and single-walled carbon nanotubes (SWCNTs). Optically transparent and small-sized GO nanosheets, with minimal sp2 domains, were successfully fabricated by step-wise oxidation and exfoliation of graphite. We demonstrated that under-coated HOGO further decreases the sheet resistance of the SWCNT film top-coated with HOGO by increasing the contact area between the SWCNTs and HOGO nanosheets by generating hole carriers in the SWCNT as a result of charge transfer. Moreover, HOGO nanosheets with AgNWs contribute to the efficient thermal joining of AgNW networks on plastic substrates by limiting the thermal embedding of AgNWs into the plastic surface, resulting in efficient decrease of the sheet resistance. Furthermore, flexible organic photovoltaic cells with GO-modified AgNW anodes on a flexible substrate were successfully demonstrated.Atomically thin and two-dimensional graphene oxide (GO) is a very fascinating material because of its functional groups, high transparency, and solution processability. Here we show that highly oxidized GO (HOGO) nanosheets serve as an effective interfacial modifier of transparent conducting films with one-dimensional (1D) silver nanowires (AgNWs) and single-walled carbon nanotubes (SWCNTs). Optically transparent and small-sized GO nanosheets, with minimal sp2 domains, were successfully fabricated by step-wise oxidation and exfoliation of graphite. We demonstrated that under-coated HOGO further decreases the sheet resistance of the SWCNT film top-coated with HOGO by increasing the contact area between the SWCNTs and HOGO nanosheets by generating hole carriers in the SWCNT as a result of charge

  7. Surface thermal oxidation on titanium implants to enhance osteogenic activity and in vivo osseointegration

    NASA Astrophysics Data System (ADS)

    Wang, Guifang; Li, Jinhua; Lv, Kaige; Zhang, Wenjie; Ding, Xun; Yang, Guangzheng; Liu, Xuanyong; Jiang, Xinquan

    2016-08-01

    Thermal oxidation, which serves as a low-cost, effective and relatively simple/facile method, was used to modify a micro-structured titanium surface in ambient atmosphere at 450 °C for different time periods to improve in vitro and in vivo bioactivity. The surface morphology, crystallinity of the surface layers, chemical composition and chemical states were evaluated by field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Cell behaviours including cell adhesion, attachment, proliferation, and osteogenic differentiation were observed in vitro study. The ability of the titanium surface to promote osseointegration was evaluated in an in vivo animal model. Surface thermal oxidation on titanium implants maintained the microstructure and, thus, both slightly changed the nanoscale structure of titanium and enhanced the crystallinity of the titanium surface layer. Cells cultured on the three oxidized titanium surfaces grew well and exhibited better osteogenic activity than did the control samples. The in vivo bone-implant contact also showed enhanced osseointegration after several hours of oxidization. This heat-treated titanium enhanced the osteogenic differentiation activity of rBMMSCs and improved osseointegration in vivo, suggesting that surface thermal oxidation could potentially be used in clinical applications to improve bone-implant integration.

  8. Surface thermal oxidation on titanium implants to enhance osteogenic activity and in vivo osseointegration

    PubMed Central

    Wang, Guifang; Li, Jinhua; Lv, Kaige; Zhang, Wenjie; Ding, Xun; Yang, Guangzheng; Liu, Xuanyong; Jiang, Xinquan

    2016-01-01

    Thermal oxidation, which serves as a low-cost, effective and relatively simple/facile method, was used to modify a micro-structured titanium surface in ambient atmosphere at 450 °C for different time periods to improve in vitro and in vivo bioactivity. The surface morphology, crystallinity of the surface layers, chemical composition and chemical states were evaluated by field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Cell behaviours including cell adhesion, attachment, proliferation, and osteogenic differentiation were observed in vitro study. The ability of the titanium surface to promote osseointegration was evaluated in an in vivo animal model. Surface thermal oxidation on titanium implants maintained the microstructure and, thus, both slightly changed the nanoscale structure of titanium and enhanced the crystallinity of the titanium surface layer. Cells cultured on the three oxidized titanium surfaces grew well and exhibited better osteogenic activity than did the control samples. The in vivo bone-implant contact also showed enhanced osseointegration after several hours of oxidization. This heat-treated titanium enhanced the osteogenic differentiation activity of rBMMSCs and improved osseointegration in vivo, suggesting that surface thermal oxidation could potentially be used in clinical applications to improve bone-implant integration. PMID:27546196

  9. ANAEROBIC DDT BIOTRANSFORMATION: ENHANCEMENT BY APPLICATION OF SURFACTANTS AND LOW OXIDATION REDUCTION POTENTIAL

    EPA Science Inventory

    Enhancement of anaerobic DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane) biotransformation by mixed cultures was studied with application of surfactants and oxidation reduction potential reducing agents. Without amendments, DDT transformation resulted mainly in the pr...

  10. ANAEROBIC DDT BIOTRANSFORMATION: ENHANCEMENT BY APPLICATION OF SURFACTANTS AND LOW OXIDATION REDUCTION POTENTIAL

    EPA Science Inventory

    Enhancement of anaerobic DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane) biotransformation by mixed cultures was studied with application of surfactants and oxidation reduction potential reducing agents. Without amendments, DDT transformation resulted mainly in the pr...

  11. A Neat Trick Using Oxalic Acid Dihydrate and Potassium Permanganate and Other Experiments with Small Organic Amine or Oxygenated Compounds

    ERIC Educational Resources Information Center

    Kelland, Malcolm A.

    2011-01-01

    Solid potassium permanganate (KMnO[subscript 4]) is shown to react in a variety of ways with small organic amines or oxygenated compounds depending on whether they are liquids or solids and whether water is present. In particular, its reaction with solid oxalic acid dihydrate can be initiated by the moisture in one's breath, making an intriguing…

  12. Comparative effects of copper sulfate or potassium permanganate on channel catfish concurrently infected with Flavobacterium columnare and Ichthyobodo necator

    USDA-ARS?s Scientific Manuscript database

    An opportunistic study was conducted to determine the effects of two chemical therapeutants on channel catfish (CCF) Ictalurus punctatus concurrently infected Flavobacterium columnare and Ichthyobodo necator. Copper sulfate (CuSO4) and potassium permanganate (KMnO4) were investigated for their abil...

  13. A Neat Trick Using Oxalic Acid Dihydrate and Potassium Permanganate and Other Experiments with Small Organic Amine or Oxygenated Compounds

    ERIC Educational Resources Information Center

    Kelland, Malcolm A.

    2011-01-01

    Solid potassium permanganate (KMnO[subscript 4]) is shown to react in a variety of ways with small organic amines or oxygenated compounds depending on whether they are liquids or solids and whether water is present. In particular, its reaction with solid oxalic acid dihydrate can be initiated by the moisture in one's breath, making an intriguing…

  14. Enhanced transparent conducting networks on plastic substrates modified with highly oxidized graphene oxide nanosheets.

    PubMed

    Woo, Jong Seok; Sin, Dong Hun; Kim, Haena; Jang, Jeong In; Kim, Ho Young; Lee, Geon-Woong; Cho, Kilwon; Park, Soo-Young; Han, Joong Tark

    2016-03-28

    Atomically thin and two-dimensional graphene oxide (GO) is a very fascinating material because of its functional groups, high transparency, and solution processability. Here we show that highly oxidized GO (HOGO) nanosheets serve as an effective interfacial modifier of transparent conducting films with one-dimensional (1D) silver nanowires (AgNWs) and single-walled carbon nanotubes (SWCNTs). Optically transparent and small-sized GO nanosheets, with minimal sp(2) domains, were successfully fabricated by step-wise oxidation and exfoliation of graphite. We demonstrated that under-coated HOGO further decreases the sheet resistance of the SWCNT film top-coated with HOGO by increasing the contact area between the SWCNTs and HOGO nanosheets by generating hole carriers in the SWCNT as a result of charge transfer. Moreover, HOGO nanosheets with AgNWs contribute to the efficient thermal joining of AgNW networks on plastic substrates by limiting the thermal embedding of AgNWs into the plastic surface, resulting in efficient decrease of the sheet resistance. Furthermore, flexible organic photovoltaic cells with GO-modified AgNW anodes on a flexible substrate were successfully demonstrated.

  15. Synthesis, characterization and enhanced antimicrobial activity of reduced graphene oxide-zinc oxide nanocomposite

    NASA Astrophysics Data System (ADS)

    Singh Rajaura, Rajveer; Sharma, Vinay; Shrivastava Ronin, Rishabh; Gupta, Deepak K.; Srivastava, Subodh; Agrawal, Kailash; Vijay, Y. K.

    2017-02-01

    In this work, we report a simple and facile one-pot chemical approach of the decoration of uniform zinc oxide nanoparticles (ZnO NPs) on reduced graphene oxide (GO) and a study of its antimicrobial activity. The nanocomposite was fully characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), x-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). TEM and SEM images clearly indicated the presence of Graphene sheets decorated with uniformly sized zinc oxide nanoparticles. Further, as an application of rGO-ZnO nanocomposites, their superior antibacterial activity was demonstrated on the Escherichia coli MTCC40 bacterial strain, using the standard disk diffusion method. This clearly showed that rGO-ZnO nanocomposites exhibited more pronounced antibacterial activity than rGO alone. This feature was revealed to be due to increased biocompatibility of PEGylated rGO-ZnO nanocomposites. In conclusion, the as-synthesized nanocomposite showed excellent antibacterial activity and has great potential for biomedical application.

  16. Tailoring micro-mesoporosity in activated carbon fibers to enhance SO₂ catalytic oxidation.

    PubMed

    Diez, Noel; Alvarez, Patricia; Granda, Marcos; Blanco, Clara; Gryglewicz, Grażyna; Wróbel-Iwaniec, Iwona; Sliwak, Agata; Machnikowski, Jacek; Menendez, Rosa

    2014-08-15

    Enhanced SO2 adsorption of activated carbon fibers is obtained by tailoring a specific micro-mesoporous structure in the fibers. This architecture is obtained via metal catalytic activation of the fibers with a novel precursor, cobalt naphthenate, which contrary to other precursors, also enhances spinnability and carbon fiber yield. In the SO2 oxidation, it is demonstrated that the combination of micropores and large mesopores is the main factor for an enhanced catalytic activity which is superior to that observed in other similar microporous activated carbon fibers. This provides an alternative way for the development of a new generation of catalytic material.

  17. Enhanced Power Stability for Proton Conducting Solid Oxides Fuel Cells

    SciTech Connect

    Boris Merinov; William A. Goddard III; Sossina Haile; Adri van Duin; Peter Babilo; Sang Soo Han

    2005-12-29

    In order to provide the basis for a rational approach to improving the performance of Y-doped BaZrO{sub 3} electrolytes for proton conducting ceramic fuel cells, we carried out a series of coupled computational and experimental studies to arrive at a consensus view of the characteristics affecting the proton conductivity of these systems. The computational part of the project developed a practical first principles approach to predicting the proton mobility as a function of temperature and doping for polycrystalline systems. This is a significant breakthrough representing the first time that first principles methods have been used to study diffusion across grain boundaries in such systems. The basis for this breakthrough was the development of the ReaxFF reactive force field that accurately describes the structure and energetics of Y-doped BaZrO{sub 3} as the proton hops from site to site. The ReaxFF parameters are all derived from an extensive set of quantum mechanics calculations on various clusters, two dimensionally infinite slabs, and three dimensionally infinite periodic systems for combinations of metals, metal alloys, metal oxides, pure and Y-doped BaZrO{sub 3}, including chemical reaction pathways and proton transport pathways, structures. The ReaxFF force field enables molecular dynamics simulations to be carried out quickly for systems with {approx} 10,000 atoms rather than the {approx}100 or so practical for QM. The first 2.5 years were spent on developing and validating the ReaxFF and we have only had an opportunity to apply these methods to only a few test cases. However these simulations lead to transport properties (diffusion coefficients and activation energy) for multi-granular systems in good agreement with current experimental results. Now that we have validated the ReaxFF for diffusion across grain boundaries, we are in the position of being able to use computation to explore strategies to improve the diffusion of protons across grain boundaries

  18. One-pot synthesis of cuprous oxide-reduced graphene oxide nanocomposite with enhanced photocatalytic and electrocatalytic performance

    NASA Astrophysics Data System (ADS)

    Han, Fugui; Li, Heping; Yang, Jun; Cai, Xiaodong; Fu, Li

    2016-03-01

    We report on the facile one-step synthesis of porous cuprous oxide nanoparticles on reduced graphene oxide (Cu2O-RGO) by synchronously reducing Cu2+ ions and GO with ethylene glycol. The basic chemical components, crystal structure and surface morphology of prepared nanocomposite was carefully characterized. The photocatalytic activities of the as-prepared nanocomposite was investigated by photodegrading methylene blue (MB) under visible light. The electrocatalytic property of the nanocomposite was investigated by electrocatalytic determination of acetaminophen. The results indicate that the corporation of RGO with Cu2O nanoparticles could high enhance the both photocatalytic and electrocatalytic properties. Moreover, we found that the content of RGO introduced into nanocomposite could highly affect the product properties.

  19. Nitric Oxide Mediates Glutamate-Linked Enhancement of cGMP Levels in the Cerebellum

    NASA Astrophysics Data System (ADS)

    Bredt, David S.; Snyder, Solomon H.

    1989-11-01

    Nitric oxide, which mediates influences of numerous neurotransmitters and modulators on vascular smooth muscle and leukocytes, can be formed in the brain from arginine by an enzymatic activity that stoichiometrically generates citrulline. We show that glutamate and related amino acids, such as N-methyl-D-aspartate, markedly stimulate arginine-citrulline transformation in cerebellar slices stoichiometrically with enhancement of cGMP levels. Nω-monomethyl-L-arginine blocks the augmentation both of citrulline and cGMP with identical potencies. Arginine competitively reverses both effects of Nω-monomethyl-L-arginine with the same potencies. Hemoglobin, which complexes nitric oxide, prevents the stimulation by N-methyl-D-aspartate of cGMP levels, and superoxide dismutase, which elevates nitric oxide levels, increases cGMP formation. These data establish that nitric oxide mediates the stimulation by glutamate of cGMP formation.

  20. Nitric oxide mediates glutamate-linked enhancement of cGMP levels in the cerebellum.

    PubMed

    Bredt, D S; Snyder, S H

    1989-11-01

    Nitric oxide, which mediates influences of numerous neurotransmitters and modulators on vascular smooth muscle and leukocytes, can be formed in the brain from arginine by an enzymatic activity that stoichiometrically generates citrulline. We show that glutamate and related amino acids, such as N-methyl-D-aspartate, markedly stimulate arginine--citrulline transformation in cerebellar slices stoichiometrically with enhancement of cGMP levels. N omega-monomethyl-L-arginine blocks the augmentation both of citrulline and cGMP with identical potencies. Arginine competitively reverses both effects of N omega-monomethyl-L-arginine with the same potencies. Hemoglobin, which complexes nitric oxide, prevents the stimulation by N-methyl-D-aspartate of cGMP levels, and superoxide dismutase, which elevates nitric oxide levels, increases cGMP formation. These data establish that nitric oxide mediates the stimulation by glutamate of cGMP formation.

  1. Nitric oxide mediates glutamate-linked enhancement of cGMP levels in the cerebellum

    SciTech Connect

    Bredt, D.S.; Snyder, S.H. )

    1989-11-01

    Nitric oxide, which mediates influences of numerous neurotransmitters and modulators on vascular smooth muscle and leukocytes, can be formed in the brain from arginine by an enzymatic activity that stoichiometrically generates citrulline. The authors show that glutamate and related amino acids, such as N-methyl-D-aspartate, markedly stimulate arginine-citrulline transformation in cerebellar slices stoichiometrically with enhancement of cGMP levels. N{sup {omega}}-monomethyl-L-arginine blocks the augmentation both of citrulline and cGMP with identical potencies. Arginine competitively reverses both effects of N{sup {omega}}-monomethyl-L-arginine with the same potencies. Hemoglobin, which complexes nitric oxide, prevents the stimulation by N-methyl-D-aspartate of cGMP levels, and superoxide dismutase, which elevates nitric oxide levels, increases cGMP formation. These data establish that nitric oxide mediates the stimulation by glutamate of cGMP formation.

  2. Biopolyester-based systems containing naturally occurring compounds with enhanced thermo-oxidative stability.

    PubMed

    Arrigo, Rossella; Morici, Elisabetta; Dintcheva, Nadka Tzankova

    2016-11-02

    This work presents a sustainable approach for the stabilization of polylactic acid (PLA) against thermo-oxidative aging. Naturally occurring phenolic and polyphenolic compounds, such as ferulic acid (FerAc), vanillic acid (VanAc), quercetin (Querc) and vitamin E (VitE), were introduced into PLA. The preliminary characterization of the systems formulated containing different amounts of natural stabilizers showed that all compounds used acted as plasticizers, leading to a decrease in rheological functions with respect to neat PLA, without significantly modifying the crystallinity of the raw material. The study of the thermo-oxidative behavior of neat PLA and PLA/natural compound systems, performed by spectrometric and thermal analyses, indicated that all stabilizers considered were able to exert a remarkable antioxidant action against thermo-oxidative phenomena. All natural compounds considered are thus proposed as ecofriendly stabilizers, to get fully bio-based polymer systems with enhanced thermo-oxidative stability, suitable for biomedical applications.

  3. Enhanced Reactivity in Dioxirane C-H Oxidations via Strain Release: A Computational and Experimental Study

    PubMed Central

    Zou, Lufeng; Paton, Robert S.; Eschenmoser, Albert; Newhouse, Timothy R.; Baran, Phil S.; Houk, K. N.

    2013-01-01

    The site- and stereo-selectivities of C-H oxidations of substituted cyclohexanes and trans-decalins by dimethyldioxirane (DMDO) were investigated computationally with quantum mechanical density functional theory (DFT). The multi-configuration CASPT2 method was employed on model systems to establish the preferred mechanism and transition state geometry. The reaction pathway involving a rebound step is established to account for the retention of stereochemistry. The oxidation of sclareolide with dioxirane reagents is reported, including the oxidation by the in situ generated tBu-TFDO, a new dioxirane that better discriminates between C-H bonds based on steric effects. The release of 1,3-diaxial strain in the transition state contributes to the site selectivity and enhanced axial reactivity for tertiary C-H bonds, a result of the lowering of distortion energy. In addition to this strain release factor, steric and inductive effects contribute to the rates of C-H oxidation by dioxiranes. PMID:23461537

  4. Substrate and laser power dependence of surface-enhanced Raman scattering from a silver oxide film.

    PubMed

    Iwanabe, Yasuhiko; Fujimaki, Makoto; Awazu, Koichi; Horiuchi, Toshiyuki; Tominaga, Junji

    2006-03-28

    We report a method to improve the efficiency of surface-enhanced Raman scattering (SERS) from a silver oxide film. A 632.8 nm He-Ne laser beam was focused on silver oxide films deposited on different substrates (silica, TiO2, Si). We found that the substrate material greatly affected the SERS efficiency, and that silica substrate showed the highest efficiency among the materials measured. Scanning electron microscopy observations revealed that silver nanoparticles were generated within the focused laser spot. Computer simulations of the thermal profile based upon data from experimental observations were also carried out. It was found that the temperature of the silver oxide film differed greatly according to the substrate. We infer that substrates that allow higher silver-oxide-film temperatures to be attained are more suitable for efficient SERS.

  5. Enhanced electroluminescence from nanoscale silicon p+ -n junctions made with an anodic aluminum oxide pattern.

    PubMed

    Hong, T; Chen, T; Ran, G Z; Wen, J; Li, Y Z; Dai, T; Qin, G G

    2010-01-15

    An enhancement of the electroluminescence (EL) from nanoscale silicon p(+)-n junctions made with an anodic aluminum oxide (AAO) pattern was demonstrated. The nanoporous AAO pattern with a pore density of 1.4 x 10(10) cm(-2) and a pore diameter of 50 +/- 10 nm was fabricated by the two-step anodic oxidation method on a n-type silicon wafer. The nanoscale AAO patterned Si p(+)-n junctions achieved an EL enhancement factor up to about 5 compared to the unpatterned Si p(+)-n junctions. The enhancement may originate from a reduction of nonradiative recombination due to partial passivation of the Si surface by the AAO pattern and improvement of the light extraction due to surface nanotextures.

  6. The Otto Aufranc Award: Enhanced Biocompatibility of Stainless Steel Implants by Titanium Coating and Microarc Oxidation

    PubMed Central

    Lim, Young Wook; Kwon, Soon Yong; Sun, Doo Hoon

    2010-01-01

    Background Stainless steel is one of the most widely used biomaterials for internal fixation devices, but is not used in cementless arthroplasty implants because a stable oxide layer essential for biocompatibility cannot be formed on the surface. We applied a Ti electron beam coating, to form oxide layer on the stainless steel surface. To form a thicker oxide layer, we used a microarc oxidation process on the surface of Ti coated stainless steel. Modification of the surface using Ti electron beam coating and microarc oxidation could improve the ability of stainless steel implants to osseointegrate. Questions/purposes The ability of cells to adhere to grit-blasted, titanium-coated, microarc-oxidated stainless steel in vitro was compared with that of two different types of surface modifications, machined and titanium-coated, and microarc-oxidated. Methods We performed energy-dispersive x-ray spectroscopy and scanning electron microscopy investigations to assess the chemical composition and structure of the stainless steel surfaces and cell morphology. The biologic responses of an osteoblastlike cell line (SaOS-2) were examined by measuring proliferation (cell proliferation assay), differentiation (alkaline phosphatase activity), and attraction ability (cell migration assay). Results Cell proliferation, alkaline phosphatase activity, migration, and adhesion were increased in the grit-blasted, titanium-coated, microarc-oxidated group compared to the two other groups. Osteoblastlike cells on the grit-blasted, titanium-coated, microarc-oxidated surface were strongly adhered, and proliferated well compared to those on the other surfaces. Conclusions The surface modifications we used (grit blasting, titanium coating, microarc oxidation) enhanced the biocompatibility (proliferation and migration of osteoblastlike cells) of stainless steel. Clinical Relevance This process is not unique to stainless steel; it can be applied to many metals to improve their biocompatibility

  7. A graphene meta-interface for enhancing the stretchability of brittle oxide layers

    NASA Astrophysics Data System (ADS)

    Won, Sejeong; Jang, Jae-Won; Choi, Hyung-Jin; Kim, Chang-Hyun; Lee, Sang Bong; Hwangbo, Yun; Kim, Kwang-Seop; Yoon, Soon-Gil; Lee, Hak-Joo; Kim, Jae-Hyun; Lee, Soon-Bok

    2016-02-01

    Oxide materials have recently attracted much research attention for applications in flexible and stretchable electronics due to their excellent electrical properties and their compatibility with established silicon semiconductor processes. Their widespread uptake has been hindered, however, by the intrinsic brittleness and low stretchability. Here we investigate the use of a graphene meta-interface to enhance the electromechanical stretchability of fragile oxide layers. Electromechanical tensile tests of indium tin oxide (ITO) layers on polymer substrates were carried out with in situ observations using an optical microscope. It was found that the graphene meta-interface reduced the strain transfer between the ITO layer and the substrate, and this behavior was well described using a shear lag model. The graphene meta-interface provides a novel pathway for realizing flexible and stretchable electronic applications based on oxide layers.Oxide materials have recently attracted much research attention for applications in flexible and stretchable electronics due to their excellent electrical properties and their compatibility with established silicon semiconductor processes. Their widespread uptake has been hindered, however, by the intrinsic brittleness and low stretchability. Here we investigate the use of a graphene meta-interface to enhance the electromechanical stretchability of fragile oxide layers. Electromechanical tensile tests of indium tin oxide (ITO) layers on polymer substrates were carried out with in situ observations using an optical microscope. It was found that the graphene meta-interface reduced the strain transfer between the ITO layer and the substrate, and this behavior was well described using a shear lag model. The graphene meta-interface provides a novel pathway for realizing flexible and stretchable electronic applications based on oxide layers. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05412e

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

    PubMed

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

    2012-02-01

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

  9. Enhancement of mite antigen-induced histamine release by deuterium oxide from leucocytes of chronic urticarial patients

    SciTech Connect

    Numata, T.; Yamamoto, S.; Yamura, T.

    1981-09-01

    The mite antigen-induced histamine release from leucocytes of chronic urticarial patients was enhanced in the presence of deuterium oxide, which stabilizes microtubules. This enhancing effect of deuterium oxide on the histamine release from leucocytes may provide a useful means for the detection of allergens in vitro in chronic urticaria.

  10. Air-Impregnated Nanoporous Anodic Aluminum Oxide Layers for Enhancing the Corrosion Resistance of Aluminum.

    PubMed

    Jeong, Chanyoung; Lee, Junghoon; Sheppard, Keith; Choi, Chang-Hwan

    2015-10-13

    Nanoporous anodic aluminum oxide layers were fabricated on aluminum substrates with systematically varied pore diameters (20-80 nm) and oxide thicknesses (150-500 nm) by controlling the anodizing voltage and time and subsequent pore-widening process conditions. The porous nanostructures were then coated with a thin (only a couple of nanometers thick) Teflon film to make the surface hydrophobic and trap air in the pores. The corrosion resistance of the aluminum substrate was evaluated by a potentiodynamic polarization measurement in 3.5 wt % NaCl solution (saltwater). Results showed that the hydrophobic nanoporous anodic aluminum oxide layer significantly enhanced the corrosion resistance of the aluminum substrate compared to a hydrophilic oxide layer of the same nanostructures, to bare (nonanodized) aluminum with only a natural oxide layer on top, and to the latter coated with a thin Teflon film. The hydrophobic nanoporous anodic aluminum oxide layer with the largest pore diameter and the thickest oxide layer (i.e., the maximized air fraction) resulted in the best corrosion resistance with a corrosion inhibition efficiency of up to 99% for up to 7 days. The results demonstrate that the air impregnating the hydrophobic nanopores can effectively inhibit the penetration of corrosive media into the pores, leading to a significant improvement in corrosion resistance.

  11. Characterization of ultrathin silicon oxide films with mirror-enhanced polarized reflectance Fourier transform infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Cui, Zhenjiang; Takoudis, Christos G.

    2001-05-01

    Ultrathin silicon oxide films thermally grown on Si (100) are characterized with mirror-enhanced polarized reflectance Fourier transform infrared spectroscopy (MEPR-FTIR). MEPR-FTIR is proposed to effectively probe properties of ultrathin films. Using a mirror and a polarizer, MEPR-FTIR overcomes the difficulty of weak IR intensities normally encountered in ultrathin gate dielectrics such as SiO2; the intensity of the silicon oxide longitudinal optical (LO) mode is found to increase by a factor of about 20. Therefore, FTIR spectrometers with sensitivity down to 0.01% may allow even submonolayer probing of silicon oxide on Si substrates. The relationship between film thickness and IR intensity of the LO mode at 1252 cm-1 is presented for silicon oxide films as thin as a few Å thick. Independent measurements with ellipsometry, cross-sectional transmission electron microscopy, and x-ray photoelectron spectroscopy as well as theoretical predictions using the general Fresnel function are utilized. Although nonlinear overall, the theoretically predicted relationship between the MEPR-FTIR intensity and film thickness is almost linear within the range 0-50 Å. Experimental data are shown to agree very well with the theoretical calculations for two different kinds of oxides: thermal oxides grown at 1050 °C and native oxides. Such results suggest that the MEPR-FTIR can be useful as an ex situ or in situ technique for thickness measurements and, in fact, for other properties of ultrathin gate dielectrics.

  12. Use of amine oxide surfactants for chemical flooding EOR (enhanced oil recovery)

    SciTech Connect

    Olsen, D.K.

    1989-11-01

    The use of amine oxides with and without alcohols as cosolvents, and in combination with other surfactants as mixed micellar formulations for enhanced oil recovery by surfactant flooding was investigated. Amine oxides are a salt-tolerant class of surfactants that produce low interfacial tension and can develop viscosity without the addition of polymers. These salt-tolerant formulations generate three-phase regions with hydrocarbons over a broad salinity range, develop moderate solubilization, and produce low interfacial tensions, however oil recovery from amine oxide-alcohol phase behavior optimized formulations was directly dependent upon the quantity of surfactant injected. The large pore volume and high concentration of surfactant required prohibits their economic use as the primary surfactant in chemical flooding EOR. Dimethylalkylamine oxides are useful as cosurfactants and viscosifiers in formulations with other surfactants for chemical flooding EOR but the use of ethoxylated and propoxylated amine oxides should be avoided due to the decomposition of these amine oxides under reservoir conditions. Phase behavior, phase inversion temperatures, and viscosity scans have been correlated with surfactant structures to provide a guide for amine oxide applications in chemical flooding. 36 refs., 5 figs., 6 tabs.

  13. Comparison of Calcium Phosphate and Zinc Oxide Nanoparticles as Dermal Penetration Enhancers for Albumin.

    PubMed

    Shokri, Narges; Javar, H A

    2015-01-01

    Dermal drug delivery is highly preferred by patients due to its several advantages. Protein therapeutics have attracted huge attention recently. Since dermal delivery of proteins encounter problems, in this investigation, zinc oxide nanoparticles and calcium phosphate nanoparticles were compared as enhancers for dermal permeation of albumin. Albumin was applied simultaneously with zinc oxide nanoparticles or calcium phosphate nanoparticles on pieces of mouse skin. Skin permeation of albumin over time was determined using a diffusion cell. Skin distribution of the nanoparticles and albumin over time was determined by optical and fluorescence microscopy. Zinc oxide nanoparticles and calcium phosphate nanoparticles acted as enhancers for skin permeation of albumin. Cumulative permeated albumin in presence of zinc oxide nanoparticles after 0, 0.5, 1, 1.5 and 2 h, were 0±0, 11.7±3.3, 21.1±3.5, 40.2±3.6 and 40.2±3.6 mg, respectively and in presence of calcium phosphate nanoparticles were 0±0, 20.9±7.4, 33.8±5.5, 33.8±3.7 and 33.8±3.7 mg, respectively. After 0.5 h, little amount of albumin was permeated in presence of every kind of the nanoparticles. After 0.5 or 1 h, the permeated albumin in presence of calcium phosphate nanoparticles was more than that in presence of zinc oxide nanoparticles and after 1.5 h the permeated albumin in presence of zinc oxide nanoparticles was more than that in presence of calcium phosphate nanoparticles. Images of skin distribution of the two nanoparticles over time, were somewhat different and distribution of albumin correlated with the distribution of the nanoparticles alone. The profiles of albumin permeation (in presence of each of the nanoparticles) versus time was delayed and linear for both nanoparticles while the slope for calcium phosphate nanoparticles was higher than zinc oxide nanoparticles. The enhancer effect of zinc oxide nanoparticles was stronger while the enhancer effect of calcium phosphate nanoparticles was

  14. Comparison of Calcium Phosphate and Zinc Oxide Nanoparticles as Dermal Penetration Enhancers for Albumin

    PubMed Central

    Shokri, Narges; Javar, H. A.

    2015-01-01

    Dermal drug delivery is highly preferred by patients due to its several advantages. Protein therapeutics have attracted huge attention recently. Since dermal delivery of proteins encounter problems, in this investigation, zinc oxide nanoparticles and calcium phosphate nanoparticles were compared as enhancers for dermal permeation of albumin. Albumin was applied simultaneously with zinc oxide nanoparticles or calcium phosphate nanoparticles on pieces of mouse skin. Skin permeation of albumin over time was determined using a diffusion cell. Skin distribution of the nanoparticles and albumin over time was determined by optical and fluorescence microscopy. Zinc oxide nanoparticles and calcium phosphate nanoparticles acted as enhancers for skin permeation of albumin. Cumulative permeated albumin in presence of zinc oxide nanoparticles after 0, 0.5, 1, 1.5 and 2 h, were 0±0, 11.7±3.3, 21.1±3.5, 40.2±3.6 and 40.2±3.6 mg, respectively and in presence of calcium phosphate nanoparticles were 0±0, 20.9±7.4, 33.8±5.5, 33.8±3.7 and 33.8±3.7 mg, respectively. After 0.5 h, little amount of albumin was permeated in presence of every kind of the nanoparticles. After 0.5 or 1 h, the permeated albumin in presence of calcium phosphate nanoparticles was more than that in presence of zinc oxide nanoparticles and after 1.5 h the permeated albumin in presence of zinc oxide nanoparticles was more than that in presence of calcium phosphate nanoparticles. Images of skin distribution of the two nanoparticles over time, were somewhat different and distribution of albumin correlated with the distribution of the nanoparticles alone. The profiles of albumin permeation (in presence of each of the nanoparticles) versus time was delayed and linear for both nanoparticles while the slope for calcium phosphate nanoparticles was higher than zinc oxide nanoparticles. The enhancer effect of zinc oxide nanoparticles was stronger while the enhancer effect of calcium phosphate nanoparticles was

  15. Injectable Silica–Permanganate Gel as a Slow-Release MnO4- Source for Groundwater Remediation. Rheological Properties and Release Dynamics

    SciTech Connect

    Yang, Shuo; Oostrom, Martinus; Truex, Michael J.; Li, G.; Zhong, Lirong

    2016-01-12

    Injectable slow-release permanganate gel (ISRPG), formed by mixing KMnO4 solution with fumed silica powder, may have a potential application in remediating chlorinated solvent plumes in groundwater. A series of batch, column, and flow cell experiments has been completed to test the gel behavior under a variety of conditions. The experiments have provided information on ISRPG rheology, permanganate (MnO4- ) release dynamics and distribution, and trichloroethene (TCE) degradation by ISRPG-released oxidant. The gel possesses remarkable shear thinning characteristics, resulting in a relative low viscosity during mixing, and facilitating its subsurface injection and distribution. Batch tests revealed that MnO4- was diffused out from ISRPG into water while the gel did not dissolve or disperse into water but maintained its initial shape. Column experiments showed that MnO4- release from ISRPG lasted considerably longer than the release from aqueous solution. TCE degradation by ISRPG-released MnO4- was much more effective than that when MnO4- was delivered using aqueous solution injection. In two-dimensional flow cell experiments, it was demonstrated that ISRPG slowly released a long-lasting low concentration MnO4- plume sufficient for remediation and sustainable in an aquifer for a long period of time.

  16. Test Report for Permanganate and Cold Strontium Strike for Tank 241-AN-102

    SciTech Connect

    Duncan, James B.; Huber, Heinz J.; Smalley, Colleen S.

    2013-11-27

    Tanks 241-AN-102 and 241-AN-107 supernatants contain soluble Sr-90 and transuranic elements that require removal prior to vitrification to comply with the Waste Treatment and Immobilization Plant immobilized low-activity waste specification (WTP Contract, DE-AC27-01RV 14136, Specification 2.2.2.8, "Radionuclide Concentration Limitations") and the U.S. Nuclear Regulatory Commission provisional agreement on waste incidental to reprocessing (letter, Paperiello, C. J., "Classification of Hanford Low-Activity Tank Waste Fraction"). These two tanks have high concentrations of organics and organic complexants and are referred to as complexant concentrate tanks. A precipitation process using sodium permanganate (NaMnO{sub 4}) and strontium nitrate (Sr(NO{sub 3}){sub 2}) was developed and tested with tank waste samples to precipitate Sr-90 and transuranic elements from the supernate (PNWD-3141, Optimization of Sr/TRU Removal Conditions with Samples of AN-102 Tank Waste). Testing documented in this report was conducted to further evaluate the use of the strontium nitrate/sodium permanganate process in tank farms with a retention time of up to 12 months. Previous testing was focused on developing a process for deployment in the ultrafiltration vessels in the Waste Treatment and Immobilization Plant. This environment is different from tank farms in two important ways: the waste is diluted in the Waste Treatment and Immobilization Plant to ~5.5 M sodium, whereas the supernate in the tank farms is ~9 M Na. Secondly, while the Waste Treatment and Immobilization Plant allows for a maximum treatment time of hours to days, the in-tank farms treatment of tanks 241-AN102 and 241-AN-107 will result in a retention time of months (perhaps up to12 months) before processing. A comparative compilation of separation processes for Sr/transuranics has been published as RPP-RPT-48340, Evaluation of Alternative Strontium and Transuranic Separation Processes. This report also listed the testing

  17. Enhancing Hematite Photoanode Activity for Water Oxidation by Incorporation of Reduced Graphene Oxide.

    PubMed

    do Amaral Carminati, Saulo; Souza, Flavio L; Nogueira, Ana F

    2016-01-04

    Two effective methods to prepare reduced graphene oxide (rGO)/hematite nanostructured photoanodes and their photoelectrochemical characterization towards water splitting reactions are presented. First, graphene oxide (GO) is reduced to rGO using hydrazine in a basic solution containing tetrabutylammonium hydroxide (TBAOH), and then deposited over the nanostructured hematite photoanodes previously treated at 750 °C for 30 min. The second method follows the deposition of a paste containing a mixture of hematite nanoparticles and rGO sheets by the doctor-blade method, varying the rGO concentration. Since hematite suffers from low electron mobility, a low absorption coefficient, high recombination rates and slow reaction kinetics, the incorporation of rGO in the hematite can overcome such limitations due to graphene's exceptional properties. Using the first method, the rGO incorporation results in a photocurrent density increase from 0.56 to 0.82 mA cm(-2) at 1.23 VRHE. Our results indicate that the rGO incorporation in the hematite photoanodes shows a positive effect in the reduction of the electron-hole recombination rate.

  18. Drinking water treatment using a submerged internal-circulation membrane coagulation reactor coupled with permanganate oxidation.

    PubMed

    Zhang, Zhongguo; Liu, Dan; Qian, Yu; Wu, Yue; He, Peiran; Liang, Shuang; Fu, Xiaozheng; Li, Jiding; Ye, Changqing

    2017-06-01

    A submerged internal circulating membrane coagulation reactor (MCR) was used to treat surface water to produce drinking water. Polyaluminum chloride (PACl) was used as coagulant, and a hydrophilic polyvinylidene fluoride (PVDF) submerged hollow fiber microfiltration membrane was employed. The influences of trans-membrane pressure (TMP), zeta potential (ZP) of the suspended particles in raw water, and KMnO4 dosing on water flux and the removal of turbidity and organic matter were systematically investigated. Continuous bench-scale experiments showed that the permeate quality of the MCR satisfied the requirement for a centralized water supply, according to the Standards for Drinking Water Quality of China (GB 5749-2006), as evaluated by turbidity (<1 NTU) and total organic carbon (TOC) (<5mg/L) measurements. Besides water flux, the removal of turbidity, TOC and dissolved organic carbon (DOC) in the raw water also increased with increasing TMP in the range of 0.01-0.05MPa. High ZP induced by PACl, such as 5-9mV, led to an increase in the number of fine and total particles in the MCR, and consequently caused serious membrane fouling and high permeate turbidity. However, the removal of TOC and DOC increased with increasing ZP. A slightly positive ZP, such as 1-2mV, corresponding to charge neutralization coagulation, was favorable for membrane fouling control. Moreover, dosing with KMnO4 could further improve the removal of turbidity and DOC, thereby mitigating membrane fouling. The results are helpful for the application of the MCR in producing drinking water and also beneficial to the research and application of other coagulation and membrane separation hybrid processes. Copyright © 2016. Published by Elsevier B.V.

  19. Coherent anti-Stokes Raman scattering enhancement of thymine adsorbed on graphene oxide

    PubMed Central

    2014-01-01

    Coherent anti-Stokes Raman scattering (CARS) of carbon nanostructures, namely, highly oriented pyrolytic graphite, graphene nanoplatelets, graphene oxide, and multiwall carbon nanotubes as well CARS spectra of thymine (Thy) molecules adsorbed on graphene oxide were studied. The spectra of the samples were compared with spontaneous Raman scattering (RS) spectra. The CARS spectra of Thy adsorbed on graphene oxide are characterized by shifts of the main bands in comparison with RS. The CARS spectra of the initial nanocarbons are definitely different: for all investigated materials, there is a redistribution of D- and G-mode intensities, significant shift of their frequencies (more than 20 cm-1), and appearance of new modes about 1,400 and 1,500 cm-1. The D band in CARS spectra is less changed than the G band; there is an absence of 2D-mode at 2,600 cm-1 for graphene and appearance of intensive modes of the second order between 2,400 and 3,000 cm-1. Multiphonon processes in graphene under many photon excitations seem to be responsible for the features of the CARS spectra. We found an enhancement of the CARS signal from thymine adsorbed on graphene oxide with maximum enhancement factor about 105. The probable mechanism of CARS enhancement is discussed. PMID:24948887

  20. Core-Shell Au@Metal-Oxide Nanoparticle Electrocatalysts for Enhanced Oxygen Evolution.

    PubMed

    Strickler, Alaina L; Escudero-Escribano, Marı A; Jaramillo, Thomas F

    2017-10-11

    Enhanced catalysis for electrochemical oxygen evolution is essential for the efficacy of many renewable energy technologies, including water electrolyzers and metal-air batteries. Recently, Au supports have been shown to enhance the activity of many 3d transition metal-oxide thin films for the oxygen evolution reaction (OER) in alkaline media. Herein, we translate the beneficial impact of Au supports to high surface area, device-ready core-shell nanoparticles consisting of a Au-core and a metal-oxide shell (Au@MxOy where M = Ni, Co, Fe, and CoFe). Through a systematic evaluation, we establish trends in performance and illustrate the universal activity enhancement when employing the Au-core in the 3d transition metal-oxide nanoparticles. The highest activity particles, Au@CoFeOx, demonstrate an overpotential of 328 ± 3 mV over a 2 h stability test at 10 mA cm(-2), illustrating that strategically coupling Au support and mixed metal-oxide effects in a core-shell nanoparticle morphology is a promising avenue to achieve device-ready, high-performance OER catalysts.

  1. Coherent anti-Stokes Raman scattering enhancement of thymine adsorbed on graphene oxide

    NASA Astrophysics Data System (ADS)

    Dovbeshko, Galyna; Fesenko, Olena; Dementjev, Andrej; Karpicz, Renata; Fedorov, Vladimir; Posudievsky, Oleg Yu

    2014-05-01

    Coherent anti-Stokes Raman scattering (CARS) of carbon nanostructures, namely, highly oriented pyrolytic graphite, graphene nanoplatelets, graphene oxide, and multiwall carbon nanotubes as well CARS spectra of thymine (Thy) molecules adsorbed on graphene oxide were studied. The spectra of the samples were compared with spontaneous Raman scattering (RS) spectra. The CARS spectra of Thy adsorbed on graphene oxide are characterized by shifts of the main bands in comparison with RS. The CARS spectra of the initial nanocarbons are definitely different: for all investigated materials, there is a redistribution of D- and G-mode intensities, significant shift of their frequencies (more than 20 cm-1), and appearance of new modes about 1,400 and 1,500 cm-1. The D band in CARS spectra is less changed than the G band; there is an absence of 2D-mode at 2,600 cm-1 for graphene and appearance of intensive modes of the second order between 2,400 and 3,000 cm-1. Multiphonon processes in graphene under many photon excitations seem to be responsible for the features of the CARS spectra. We found an enhancement of the CARS signal from thymine adsorbed on graphene oxide with maximum enhancement factor about 105. The probable mechanism of CARS enhancement is discussed.

  2. Transgenic poplar expressing Arabidopsis NDPK2 enhances growth as well as oxidative stress tolerance.

    PubMed

    Kim, Yun-Hee; Kim, Myoung Duck; Choi, Young Im; Park, Sung-Chul; Yun, Dae-Jin; Noh, Eun Woon; Lee, Haeng-Soon; Kwak, Sang-Soo

    2011-04-01

    Nucleoside diphosphate kinase 2 (NDPK2) is known to regulate the expression of antioxidant genes in plants. Previously, we reported that overexpression of Arabidopsis NDPK2 (AtNDPK2) under the control of an oxidative stress-inducible SWPA2 promoter in transgenic potato and sweetpotato plants enhanced tolerance to various abiotic stresses. In this study, transgenic poplar (Populus alba × Poplus glandulosa) expressing the AtNDPK2 gene under the control of a SWPA2 promoter (referred to as SN) was generated to develop plants with enhanced tolerance to oxidative stress. The level of AtNDPK2 expression and NDPK activity in SN plants following methyl viologen (MV) treatment was positively correlated with the plant's tolerance to MV-mediated oxidative stress. We also observed that antioxidant enzyme activities such as ascorbate peroxidase, catalase and peroxidase were increased in MV-treated leaf discs of SN plants. The growth of SN plants was substantially increased under field conditions including increased branch number and stem diameter. SN plants exhibited higher transcript levels of the auxin-response genes IAA2 and IAA5. These results suggest that enhanced AtNDPK2 expression affects oxidative stress tolerance leading to improved plant growth in transgenic poplar. © 2010 The Authors. Plant Biotechnology Journal © 2010 Society for Experimental Biology, Association of Applied Biologists and Blackwell Publishing Ltd.

  3. Successful stabilization of graphene oxide in electrolyte solutions: enhancement of biofunctionalization and cellular uptake.

    PubMed

    Hong, Bong Jin; Compton, Owen C; An, Zhi; Eryazici, Ibrahim; Nguyen, SonBinh T

    2012-01-24

    Aqueous dispersions of graphene oxide are inherently unstable in the presence of electrolytes, which screen the electrostatic surface charge on these nanosheets and induce irreversible aggregation. Two complementary strategies, utilizing either electrostatic or steric stabilization, have been developed to enhance the stability of graphene oxide in electrolyte solutions, allowing it to stay dispersed in cell culture media and serum. The electrostatic stabilization approach entails further oxidation of graphene oxide to low C/O ratio (~1.1) and increases ionic tolerance of these nanosheets. The steric stabilization technique employs an amphiphilic block copolymer that serves as a noncovalently bound surfactant to minimize the aggregate-inducing nanosheet-nanosheet interactions. Both strategies can stabilize graphene oxide nanosheets with large dimensions (>300 nm) in biological media, allowing for an enhancement of >250% in the bioconjugation efficiency of streptavidin in comparison to untreated nanosheets. Notably, both strategies allow the stabilized nanosheets to be readily taken up by cells, demonstrating their excellent performance as potential drug-delivery vehicles.

  4. High-calcium diet enhances vasorelaxation in nitric oxide-deficient hypertension.

    PubMed

    Jolma, P; Kalliovalkama, J; Tolvanen, J P; Kööbi, P; Kähönen, M; Hutri-Kähönen, N; Wu, X; Pörsti, I

    2000-09-01

    Because the effects of calcium supplementation on arterial tone in nitric oxide-deficient hypertension are unknown, we investigated the influence of elevating dietary calcium from 1.1 to 3.0% in Wistar rats treated with N(G)-nitro-L-arginine methyl ester (L-NAME; 20 mg. kg(-1). day(-1)) for 8 wk. A high-calcium diet attenuated the development of hypertension induced by L-NAME and abrogated the associated impairments of endothelium-independent mesenteric arterial relaxations to nitroprusside, isoproterenol, and cromakalim. Endothelium-dependent relaxations to acetylcholine during nitric oxide synthase inhibition in vitro were decreased in L-NAME rats and improved by calcium supplementation. The inhibition of cyclooxygenase by diclofenac augmented the responses to acetylcholine in L-NAME rats but not in calcium + L-NAME rats. When hyperpolarization of smooth muscle was prevented by KCl precontraction, the responses to acetylcholine during combined nitric oxide synthase and cyclooxygenase inhibition were similar in all groups. Furthermore, superoxide dismutase enhanced the acetylcholine-induced relaxations in L-NAME rats but not in calcium + L-NAME rats. In conclusion, calcium supplementation reduced blood pressure during chronic nitric oxide synthase inhibition and abrogated the associated impairments in endothelium-dependent and -independent arterial relaxation. The augmented vasorelaxation after increased calcium intake in L-NAME hypertension may be explained by enhanced hyperpolarization and increased sensitivity to nitric oxide in arterial smooth muscle and decreased vascular production of superoxide and vasoconstrictor prostanoids.

  5. Successful Stabilization of Graphene Oxide in Electrolyte Solutions: Enhancement of Bio-functionalization and Cellular Uptake

    PubMed Central

    Hong, Bong Jin; Compton, Owen C.; An, Zhi; Eryzazici, Ibrahim; Nguyen, SonBinh T.

    2013-01-01

    Aqueous dispersions of graphene oxide are inherently unstable in the presence of electrolytes, which screen the electrostatic surface charge on these nanosheets and induce irreversible aggregation. Two complementary strategies, utilizing either electrostatic or steric stabilization, have been developed to enhance the stability of graphene oxide in electrolyte solutions, allowing it to stay dispersed in cell culture media and serum. The electrostatic stabilization approach entails further oxidation of graphene oxide to low C/O ratio (~1.03) and increases ionic tolerance of these nanosheets. The steric stabilization technique employs an amphiphilic block copolymer that serves as a non-covalently bound surfactant to minimize the aggregate-induced nanosheets-nanosheet interactions. Both strategies can stabilize graphene oxide nanosheets with large dimensions (>300 nm) in biological media, allowing for an enhancement of >250% in the bioconjugation efficiency of streptavidin in comparison to untreated nanosheets. Notably, both strategies allow the stabilized nanosheets to be readily uptake by cells, demonstrating their excellent performance as potential drug delivery vehicles. PMID:22017285

  6. Ketogenic Diets Enhance Oxidative Stress and Radio-Chemo-Therapy Responses in Lung Cancer Xenografts

    PubMed Central

    Allen, Bryan G.; Bhatia, Sudershan K.; Buatti, John M.; Brandt, Kristin E.; Lindholm, Kaleigh E.; Button, Anna M.; Szweda, Luke I.; Smith, Brian J.; Spitz, Douglas R.; Fath, Melissa A.

    2014-01-01

    Purpose Ketogenic diets (KDs) are high in fat and low in carbohydrates as well as protein which forces cells to rely on lipid oxidation and mitochondrial respiration rather than glycolysis for energy metabolism. Cancer cells (relative to normal cells) are believed to exist in a state of chronic oxidative stress mediated by mitochondrial metabolism. The current study tests the hypothesis that KDs enhance radio-chemo-therapy responses in lung cancer xenografts by enhancing oxidative stress. Experimental Design Mice bearing NCI-H292 and A549 lung cancer xenografts were fed a KD (KetoCal® 4:1 fats: proteins+carbohydrates) and treated with either conventionally fractionated (1.8-2 Gy) or hypofractionated (6 Gy) radiation as well as conventionally fractionated radiation combined with carboplatin. Mice weights and tumor size were monitored. Tumors were assessed for immuno-reactive 4-hydroxy-2-nonenal-(4HNE) modified proteins as a marker of oxidative stress as well as PCNA and γH2AX as indices of proliferation and DNA damage, respectively. Results The KD combined with radiation resulted in slower tumor growth in both NCI-H292 and A549 xenografts (p<0.05), relative to radiation alone. The KD also slowed tumor growth when combined with carboplatin and radiation, relative to control. Tumors from animals fed a KD in combination with radiation demonstrated increases in oxidative damage mediated by lipid peroxidation as determined by 4HNE-modified proteins as well as decreased proliferation as assessed by decreased immunoreactive PCNA. Conclusions These results show that a KD enhances radio-chemo-therapy responses in lung cancer xenografts by a mechanism that may involve increased oxidative stress. PMID:23743570

  7. Ketogenic diets enhance oxidative stress and radio-chemo-therapy responses in lung cancer xenografts.

    PubMed

    Allen, Bryan G; Bhatia, Sudershan K; Buatti, John M; Brandt, Kristin E; Lindholm, Kaleigh E; Button, Anna M; Szweda, Luke I; Smith, Brian J; Spitz, Douglas R; Fath, Melissa A

    2013-07-15

    Ketogenic diets are high in fat and low in carbohydrates as well as protein which forces cells to rely on lipid oxidation and mitochondrial respiration rather than glycolysis for energy metabolism. Cancer cells (relative to normal cells) are believed to exist in a state of chronic oxidative stress mediated by mitochondrial metabolism. The current study tests the hypothesis that ketogenic diets enhance radio-chemo-therapy responses in lung cancer xenografts by enhancing oxidative stress. Mice bearing NCI-H292 and A549 lung cancer xenografts were fed a ketogenic diet (KetoCal 4:1 fats: proteins+carbohydrates) and treated with either conventionally fractionated (1.8-2 Gy) or hypofractionated (6 Gy) radiation as well as conventionally fractionated radiation combined with carboplatin. Mice weights and tumor size were monitored. Tumors were assessed for immunoreactive 4-hydroxy-2-nonenal-(4HNE)-modified proteins as a marker of oxidative stress as well as proliferating cell nuclear antigen (PCNA) and γH2AX as indices of proliferation and DNA damage, respectively. The ketogenic diets combined with radiation resulted in slower tumor growth in both NCI-H292 and A549 xenografts (P < 0.05), relative to radiation alone. The ketogenic diet also slowed tumor growth when combined with carboplatin and radiation, relative to control. Tumors from animals fed a ketogenic diet in combination with radiation showed increases in oxidative damage mediated by lipid peroxidation as determined by 4HNE-modified proteins as well as decreased proliferation as assessed by decreased immunoreactive PCNA. These results show that a ketogenic diet enhances radio-chemo-therapy responses in lung cancer xenografts by a mechanism that may involve increased oxidative stress.

  8. Enhancement of oxidation resistance of NBD 200 silicon nitride ceramics by aluminum implantation

    NASA Astrophysics Data System (ADS)

    Mukundhan, Priya

    reduced by up to two orders of magnitude, the surface morphology and the phase characteristics of the oxides are enhanced as well. We have shown that aluminum implantation retards the outward diffusion of Mg2+ and lends a degree of protectiveness to the otherwise non-protective oxide layer. Diffusion studies using Mg-, Na- and Al-implanted silica model specimens have confirmed the effectiveness of Al in inhibiting the diffusion of Mg2+.

  9. Catalytically enhanced thermal decomposition of chemically grown silicon oxide layers on Si(001)

    NASA Astrophysics Data System (ADS)

    Leroy, F.; Passanante, T.; Cheynis, F.; Curiotto, S.; Bussmann, E. B.; Müller, P.

    2016-03-01

    The thermal decomposition of Si dioxide layers formed by wet chemical treatment on Si(001) has been studied by low-energy electron microscopy. Independent nucleations of voids occur into the Si oxide layers that open by reaction at the void periphery. Depending on the voids, the reaction rates exhibit large differences via the occurrence of a nonlinear growth of the void radius. This non-steady state regime is attributed to the accumulation of defects and silicon hydroxyl species at the SiO2/Si interface that enhances the silicon oxide decomposition at the void periphery.

  10. Catalytically enhanced thermal decomposition of chemically grown silicon oxide layers on Si(001)

    SciTech Connect

    Leroy, F. Passanante, T.; Cheynis, F.; Curiotto, S.; Bussmann, E. B.; Müller, P.

    2016-03-14

    The thermal decomposition of Si dioxide layers formed by wet chemical treatment on Si(001) has been studied by low-energy electron microscopy. Independent nucleations of voids occur into the Si oxide layers that open by reaction at the void periphery. Depending on the voids, the reaction rates exhibit large differences via the occurrence of a nonlinear growth of the void radius. This non-steady state regime is attributed to the accumulation of defects and silicon hydroxyl species at the SiO{sub 2}/Si interface that enhances the silicon oxide decomposition at the void periphery.

  11. Oxidized lipids enhance RANKL production by T lymphocytes: implications for lipid-induced bone loss.

    PubMed

    Graham, Lucia S; Parhami, Farhad; Tintut, Yin; Kitchen, Christina M R; Demer, Linda L; Effros, Rita B

    2009-11-01

    Osteoporosis is a systemic disease that is associated with increased morbidity, mortality and health care costs. Whereas osteoclasts and osteoblasts are the main regulators of bone homeostasis, recent studies underscore a key role for the immune system, particularly via activation-induced T lymphocyte production of receptor activator of NFkappaB ligand (RANKL). Well-documented as a mediator of T lymphocyte/dendritic cell interactions, RANKL also stimulates the maturation and activation of bone-resorbing osteoclasts. Given that lipid oxidation products mediate inflammatory and metabolic disorders such as osteoporosis and atherosclerosis, and since oxidized lipids affect several T lymphocyte functions, we hypothesized that RANKL production might also be subject to modulation by oxidized lipids. Here, we show that short term exposure of both unstimulated and activated human T lymphocytes to minimally oxidized low density lipoprotein (LDL), but not native LDL, significantly enhances RANKL production and promotes expression of the lectin-like oxidized LDL receptor-1 (LOX-1). The effect, which is also observed with 8-iso-Prostaglandin E2, an inflammatory isoprostane produced by lipid peroxidation, is mediated via the NFkappaB pathway, and involves increased RANKL mRNA expression. The link between oxidized lipids and T lymphocytes is further reinforced by analysis of hyperlipidemic mice, in which bone loss is associated with increased RANKL mRNA in T lymphocytes and elevated RANKL serum levels. Our results suggest a novel pathway by which T lymphocytes contribute to bone changes, namely, via oxidized lipid enhancement of RANKL production. These findings may help elucidate clinical associations between cardiovascular disease and decreased bone mass, and may also lead to new immune-based approaches to osteoporosis.

  12. Oxidized lipids enhance RANKL production by T lymphocytes: implications for lipid-induced bone loss

    PubMed Central

    Graham, Lucia S; Parhami, Farhad; Tintut, Yin; Kitchen, Christina M. R.; Demer, Linda L.; Effros, Rita B.

    2009-01-01

    Osteoporosis is a systemic disease that is associated with increased morbidity, mortality and health care costs. Whereas osteoclasts and osteoblasts are the main regulators of bone homeostasis, recent studies underscore a key role for the immune system, particularly via activation-induced T lymphocyte production of Receptor Activator of NFκB Ligand (RANKL). Well-documented as a mediator of T lymphocyte/dendritic cell interactions, RANKL also stimulates the maturation and activation of bone-resorbing osteoclasts. Given that lipid oxidation products mediate inflammatory and metabolic disorders such as osteoporosis and atherosclerosis, and since oxidized lipids affect several T lymphocyte functions, we hypothesized that RANKL production might also be subject to modulation by oxidized lipids. Here, we show that short term exposure of both unstimulated and activated human T lymphocytes to minimally oxidized low density lipoprotein (LDL), but not native LDL, significantly enhances RANKL production and promotes expression of the lectin-like oxidized LDL receptor-1 (LOX-1). The effect, which is also observed with 8-iso-Prostaglandin E2, an inflammatory isoprostane produced by lipid peroxidation, is mediated via the NFκB pathway, and involves increased RANKL mRNA expression. The link between oxidized lipids and T lymphocytes is further reinforced by analysis of hyperlipidemic mice, in which bone loss is associated with increased RANKL mRNA in T lymphocytes and elevated RANKL serum levels. Our results suggest a novel pathway by which T lymphocytes contribute to bone changes, namely, via oxidized lipid enhancement of RANKL production. These findings may help elucidate clinical associations between cardiovascular disease and decreased bone mass, and may also lead to new immune-based approaches to osteoporosis. PMID:19699688

  13. Effect of the potassium permanganate during papaya fruit ripening: Ethylene production

    NASA Astrophysics Data System (ADS)

    Corrêa, S. F.; Filho, M. B.; da Silva, M. G.; Oliveira, J. G.; Aroucha, E. M. M.; Silva, R. F.; Pereira, M. G.; Vargas, H.

    2005-06-01

    The effect of potassium permanganate (KMnO4) on the ripening process of papaya fruits by monitoring the ethylene emission rates is reported. The ethylene emission was monitored by a photoacoustic spectrometer. Two experimental conditions were applied, being one of them just putting the fruit alone inside the sampling chamber and the second, modifying the atmosphere by the presence of KMnO4. The use of the ethylene absorber reduces the autocatalytic process of ethylene during papaya fruit ripening. For 20 g of KMnO4 the maximal intensity of the ethylene emission decreases by a factor two. Using the same amount of KMnO4, a reduction of about 2.2% in the concentration of ethylene for a mixture of 1ppmv of ethylene in synthetic air was observed.

  14. Potassium permanganate-glutaraldehyde chemiluminescence system catalyzed by gold nanoprisms toward selective determination of fluoride.

    PubMed

    Abolhasani, Jafar; Hassanzadeh, Javad; Ghorbani-Kalhor, Ebrahim

    2016-02-01

    Gold and silver nanoparticles (NPs) are shown to exert a positive effect on the chemiluminescence (CL) reaction of permanganate aldehydes. Interestingly, between various shapes examined, Au nanoprisms have the highest beneficial effect. This effect is even more notable in the presence of sodium dodecyl sulfate (SDS) surfactant. UV-vis spectra and transmission electron microscopy were used to characterize the NP shapes and sizes. Furthermore, it was observed that iron(III) ions can slightly increase CL emission of this system. This intensification is very effective in the presence of fluoride ions (F(-)). These observations form the basis of the method for the high sensitive determination of F(-) in the 6-1200 nmol L(-1) concentration range, with a detection limit of 2.1 nmol L(-1). The proposed method has good precision and was satisfactorily used in the selective determination of low concentrations of fluoride ion in real samples. Copyright © 2015 John Wiley & Sons, Ltd.

  15. [Luminol-enhanced chemiluminescence of rabbit polymorphonuclear leukocytes: the nature of oxidants that directly induce luminol oxidation].

    PubMed

    Roshchupkin, D I; Belakina, N S; Murina, M A

    2006-01-01

    The present work deals with the reaction pathways, including the formation of hydroxyl radicals and chloroamines, which lead to luminol chemiluminescence caused by hypochlorite generation in a suspension of stimulated rabbit polymorphnonuclear leukocyte. Luminol-enhanced (0.02 mM) chemiluminescence of leukocytes stimulated by phorbol 12-myristate 13-acetate does not change in the presence of dimethyl sulfoxide at moderate concentrations (0.02-2.6 mM) at which it must show the specific ability to scavenge hydroxyl radicals. It suggests that no generation of hydroxyl radical with the participation of hypochlorite and superoxide anion takes place after the stimulation of polymorphnonuclear leukocytes. A high dimethyl sulfoxide concentrations (260 mM) a significant fall in chemiluminescence intensity, due to direct interaction of the scavenger with hypochlorite, is observed. Chemiluminescence intensity rose if luminol was added to a leukocyte suspension preliminary stimulated for 10 min. The effect results from the accumulation of hydrogen peroxide but not chloroamines. Exogenic amino acids and taurin at high concentrations (3-15 mM) weaken the chemiluminescence. The data obtained suggest that chemiluminescence in the system studied results predominantly from the direct initial reaction of hypochlorite with luminol. The chemiluminescence intensity is enhanced by hydrogen peroxide via the oxidation of luminol oxidation products.

  16. Understanding the role of gold nanoparticles in enhancing the catalytic activity of manganese oxides in water oxidation reactions.

    PubMed

    Kuo, Chung-Hao; Li, Weikun; Pahalagedara, Lakshitha; El-Sawy, Abdelhamid M; Kriz, David; Genz, Nina; Guild, Curtis; Ressler, Thorsten; Suib, Steven L; He, Jie

    2015-02-16

    The Earth-abundant and inexpensive manganese oxides (MnOx) have emerged as an intriguing type of catalysts for the water oxidation reaction. However, the overall turnover frequencies of MnOx catalysts are still much lower than that of nanostructured IrO2 and RuO2 catalysts. Herein, we demonstrate that doping MnOx polymorphs with gold nanoparticles (AuNPs) can result in a strong enhancement of catalytic activity for the water oxidation reaction. It is observed that, for the first time, the catalytic activity of MnOx/AuNPs catalysts correlates strongly with the initial valence of the Mn centers. By promoting the formation of Mn(3+) species, a small amount of AuNPs (<5%) in α-MnO2/AuNP catalysts significantly improved the catalytic activity up to 8.2 times in the photochemical and 6 times in the electrochemical system, compared with the activity of pure α-MnO2.

  17. Enhanced wet hydrogen peroxide catalytic oxidation performances based on CuS nanocrystals/reduced graphene oxide composites

    NASA Astrophysics Data System (ADS)

    Qian, Jing; Wang, Kun; Guan, Qingmeng; Li, Henan; Xu, Hui; Liu, Qian; Liu, Wei; Qiu, Baijing

    2014-01-01

    CuS nanocrystals/reduced graphene oxide (CuS NCs/rGO) composites were prepared by a facile one-pot solvothermal reaction. In this solvothermal system, thioacetamide was found to perform the dual roles of sulphide source and reducing agent, resulting in the formation of CuS NCs and simultaneous reduction of graphene oxide (GO) sheets to rGO sheets. In addition, CuS NCs/rGO composites were further used as heterogeneous catalysts in the wet hydrogen peroxide catalytic oxidation process, with methylene blue as a model organic dye. The introduction of rGO to CuS NCs could effectively enhance the catalytic activity of CuS NCs, and the resultant CuS NCs/rGO composites with a starting GO amount of 5 wt% showed the highest catalytic activity. Furthermore, the CuS NCs/rGO composites showed high catalytic activity over a broad pH operation range from 3.0 to 11.0 under ambient conditions, and still retained 90% of the original catalytic activity after reuse in five cycles.

  18. Baltimore City adopts a proactive approach to zebra mussel control using potassium permanganate

    SciTech Connect

    Balog, G.G.; Neimery, T.F.; Davis, L.S.

    1995-06-01

    In 1992, The Baltimore City Department of Public Works initiated aggressive, proactive measures to guard against the infiltration of zebra mussels into local reservoirs and river supplies, which provide raw and finished water to more than 1.6 million people in the City and five neighboring counties. After months of detailed study and planning, Baltimore City appropriated $3.66 million in July 1994 to construct zebra mussel control facilities. Three of the structures will house units that inject controlled doses of potassium permanganate into water intake pipes located in the Liberty and Loch Raven reservoirs and the Susquehanna River. In the event the zebra mussel makes its way into Maryland waters, the chemical would create a hostile environment for the mollusk preventing the mussels` colonization in the more than 20 miles of water tunnels that lead to area filtration plants. Though chlorine is preferred chemical for control in other municipalities, studies indicate that chlorine by-products, known as trihalomethanes, would near or exceed future Environmental Protection Agency standards (a maximum of 80 parts per billion) for drinking water. Consequently, it was decided to use potassium permanganate as the primary control chemical, with chlorine as an emergency backup. In addition, the City plans to construct a thermal control system as the Prettyboy reservoir intake to control the mussel threat without harming the thriving trout population found downstream from the dam. Baltimore City officials have also spearheaded a program using innovative posters to heighten public awareness to the potential harm that can result from the careless transportation of zebra mussels from infested to uninhabited waters. The City`s actions have helped ensure protected waters for Maryland residents and reduced the need for additional public spending to defend against the stealthy intruder.

  19. Mechanism of enhanced removal of quinonic intermediates during electrochemical oxidation of Orange II under ultraviolet irradiation.

    PubMed

    Li, Fazhan; Li, Guoting; Zhang, Xiwang

    2014-03-01

    The effect of ultraviolet irradiation on generation of radicals and formation of intermediates was investigated in electrochemical oxidation of the azo-dye Orange II using a TiO2-modified β-PbO2 electrode. It was found that a characteristic absorbance of quinonic compounds at 255 nm, which is responsible for the rate-determining step during aromatics degradation, was formed only in electrocatalytic oxidation. The dye can be oxidized by either HO radicals or direct electron transfer. Quinonic compounds were produced concurrently. The removal of TOC by photo-assisted electrocatalytic oxidation was 1.56 times that of the sum of the other two processes, indicating a significant synergetic effect. In addition, once the ultraviolet irradiation was introduced into the process of electrocatalytic oxidation, the degradation rate of quinonic compounds was enhanced by as much as a factor of two. The more efficient generation of HO radicals resulted from the introduction of ultraviolet irradiation in electrocatalytic oxidation led to the significant synergetic effect as well as the inhibiting effect on the accumulation of quinonic compounds.

  20. Preparation Of Electrochromic Metal Oxide Films By Plasma-Enhanced Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Benson, D. K.; Tracy, C. E.; Svensson, J. S. E. M.; Liebert, B. E.

    1987-11-01

    Laboratory procedures have been developed for depositing thin films of electrochromic metal oxides by plasma-enhanced chemical vapor deposition (PE-CVD). In this process, vapor phase reactants, such as tungsten hexafluotIde, are mixed with oxygen and excited by RF energy at a frequency of 13.56 MHz and power levels up to≍1W/cm2 substrate area. Large rates of oxide deposition have been achieved (> 8 nm/s) making this process a candidate for high-speed coating of large area substrates, such as window glass. Amorphous WO1 films prepared by PE-CVD have been shown to have electrochromic responses virtually identical to films prepared by vacuum evaporation. The lithium ion diffusion rate, for example, is approximately 1.3 x 10-11 cm2 /s at x = 0.03 in LixWO3 prepared by PE-CVD. On the other hand, molybdenum oxide films and mixed molybdenum/tungsten oxide films prepared by PE-CVD from the hexafluorides differ markedly from vacuum evaporated films. Their electrochromic responses are spectrally different and are much slower. Lithium ion diffusion rates in such Mo03 films are lower by about three orders of magnitude. These differences are tentatively attributed to a large fraction of fluorine (Mo:F ratios of the order of 2:1) which are incorporated into the molybdenum and mixed oxides, but are not incorporated into the tungsten oxides.

  1. Enhancement of octacalcium phosphate deposition on a titanium surface activated by electron cyclotron resonance plasma oxidation.

    PubMed

    Orii, Yusuke; Masumoto, Hiroshi; Honda, Yoshitomo; Anada, Takahisa; Goto, Takashi; Sasaki, Keiichi; Suzuki, Osamu

    2010-05-01

    The present study was designed to investigate whether the formation of octacalcium phosphate (OCP) is accelerated on titanium (Ti) surface by an electron cyclotron resonance (ECR) plasma oxidation at various pressures and temperatures. X-ray diffraction (XRD) of Ti-oxidized substrates showed that the rutile TiO(2) phase on its surfaces appeared at 300 degrees C and was crystallized when the oxidation temperature increased up to 600 degrees C. The thickness of TiO(2) film on the substrates increased progressively as the temperature increased. The oxidized Ti surfaces were soaked in calcium and phosphate solutions supersaturated with respect to both hydroxyapatite (HA) and OCP but slightly supersaturated with dicalcium phosphate dihydrate (DCPD). OCP crystals with a blade-like morphology were deposited as the primary crystalline phase on Ti substrates, while DCPD was included as a minor constituent. The amount of OCP deposition was maximized under 0.015 Pa in 300 degrees C. On the other hand, the oxidation temperature did not show a significant effect on the deposit in the range examined. The phase conversion from OCP to HA, determined by XRD, was demonstrated to occur even at 1 day and to advance until 7 days by immersing the Ti substrate with the deposit in simulated body fluid at 37 degrees C. The present results suggest that ECR plasma oxidation could be used to improve a Ti surface regarding its bioactivity due to the enhancement of osteoconductive OCP deposition. (c) 2010 Wiley Periodicals, Inc.

  2. Pluriformity of inflammation in multiple sclerosis shown by ultra-small iron oxide particle enhancement.

    PubMed

    Vellinga, Machteld M; Oude Engberink, Raoul D; Seewann, Alexandra; Pouwels, Petra J W; Wattjes, Mike P; van der Pol, Susanne M A; Pering, Christiane; Polman, Chris H; de Vries, Helga E; Geurts, Jeroen J G; Barkhof, Frederik

    2008-03-01

    Gadolinium-DTPA (Gd-DTPA) is routinely used as a marker for inflammation in MRI to visualize breakdown of the blood-brain barrier (BBB) in multiple sclerosis. Recent data suggest that ultra-small superparamagnetic particles of iron oxide (USPIO) can be used to visualize cellular infiltration, another aspect of inflammation. This project aimed to compare the novel USPIO particle SHU555C to the longitudinal pattern of Gd-DTPA enhancement in multiple sclerosis. Nineteen relapsing-remitting patients were screened monthly using Gd-enhanced MRI. In case of new enhancing lesions, USPIO were injected and 24 h later, MRI was performed and blood was collected to confirm USPIO loading of circulating monocytes. Lesion development was monitored by 3 monthly Gd-DTPA-enhanced scans and a final scan 7-11 months after injection. USPIO-enhancement was observed as hyperintensity on T1-weighted images, whereas no signal changes were observed on T2-weighted-gradient-echo images. In 14 patients with disease activity, 188 USPIO-positive lesions were seen, 144 of which were Gd-negative. By contrast, there were a total of 59 Gd-positive lesions, 15 of which were USPIO negative. Three patterns of USPIO-enhancement were seen: (i) focal enhancement; (ii) ring-like enhancement and (iii) return to isointensity of a previously hypointense lesion. The latter pattern was most frequently observed for lesions that turned out to be transiently hypointense on follow-up scans, and ring-enhancing lesions were less likely to evolve into black holes at follow-up than lesions without ring-like USPIO-enhancement; we speculate this to be associated with repair. In 4% of the USPIO-positive/Gd negative lesions, USPIO-enhancement preceded Gd-enhancement by 1 month. USPIO-enhancement remained visible for up to 3 months in 1.5% of all USPIO-positive lesions. In 29% of the lesions enhancing with both contrast agents, USPIO-enhancement persisted whereas Gd-enhancement had already resolved. In conclusion, the new

  3. Decoration of the layered manganese oxide birnessite with Mn(II/III) gives a new water oxidation catalyst with fifty-fold turnover number enhancement.

    PubMed

    McKendry, Ian G; Kondaveeti, Sandeep K; Shumlas, Samantha L; Strongin, Daniel R; Zdilla, Michael J

    2015-08-07

    The role of the manganese average oxidation state (AOS) in water oxidation catalysis by birnessite was investigated. Low AOS samples were most active, generating O2 immediately. Samples with a relatively high AOS showed an initial induction period and decreased turnover. Mn(ii- and iii)-enriched samples gave a 10-50 fold enhancement in turnover number.

  4. Enhanced production of oxidised mercury over the tropical Pacific Ocean: a key missing oxidation pathway

    NASA Astrophysics Data System (ADS)

    Wang, F.; Saiz-Lopez, A.; Mahajan, A. S.; Gómez Martín, J. C.; Armstrong, D.; Lemes, M.; Hay, T.; Prados-Roman, C.

    2013-08-01

    Mercury is a contaminant of global concern. It is transported in the atmosphere primarily as gaseous elemental mercury, but its reactivity and deposition to the surface environment, through which it enters the aquatic food chain, is greatly enhanced following oxidation. Measurements of oxidised mercury in the polar to sub-tropical marine boundary layer have suggested that photolytically produced bromine atoms are the primary oxidant of mercury. We report year-round measurements of elemental and oxidised mercury, along with ozone, halogen oxides (IO and BrO) and nitrogen oxides (NO2), in the marine boundary layer over the Galápagos Islands in the Equatorial Pacific. Elemental mercury concentration remained low throughout the year, while considerable concentrations of oxidised mercury occurred around midday. Our results show that the production of oxidised mercury in the tropical marine boundary layer cannot be accounted for by only bromine oxidation, or by the inclusion of ozone and hydroxyl. A two-step oxidation mechanism where the HgBr intermediate is further oxidised to Hg(II) depends critically on the stability of HgBr. If the current paradigm is considered, another oxidant is needed to explain more than 50% of the observed oxidised mercury. We show that atomic iodine could play the role of the missing oxidant, explaining not only the Hg(II) levels observed, but also the daily variability. However, more recent theoretical calculations indicate that the thermal dissociation rate of HgBr is much faster, by an order of magnitude, than previously reported, which implies that only trace gases at relatively high mixing ratios forming stable complexes with HgBr (such as HO2 and NO2) could compete to generate levels of Hg(II) similar to those observed in our study. Nevertheless, the daily variability of oxidised mercury is not well accounted for by using these new theoretically estimated rates. Furthermore, correlation analysis does not support a major role of NO2 or

  5. Lipid-enhancement of activated sludges obtained from conventional activated sludge and oxidation ditch processes.

    PubMed

    Revellame, Emmanuel D; Hernandez, Rafael; French, W Todd; Holmes, William E; Forks, Allison; Callahan, Robert

    2013-11-01

    Lipid-enhancement of activated sludges was conducted to increase the amount of saponifiable lipids in the sludges. The sludges were obtained from a conventional activated sludge (CAS) and an oxidation ditch process (ODP). Results showed 59-222% and 150-250% increase in saponifiable lipid content of the sludges from CAS and ODP, respectively. The fatty acid methyl ester (FAMEs) obtained from triacylglycerides was 57-67% (of total FAMEs) for enhanced CAS and 55-73% for enhanced ODP, a very significant improvement from 6% to 10% (CAS) and 4% to 8% (ODP). Regardless of the source, the enhancement resulted in sludges with similar fatty acid profile indicating homogenization of the lipids in the sludges. This study provides a potential strategy to utilize existing wastewater treatment facilities as source of significant amount of lipids for biofuel applications. Published by Elsevier Ltd.

  6. Impaired secondary oxidant deactivation capacity and enhanced oxidative stress in serum from alveld affected lambs.

    PubMed

    Hegge, Anne Bee; Mysterud, Ivar; Karlsen, Jan; Skulberg, Olav M; Laane, Carl M M; Schumacher, Trond; Tønnesen, Hanne Hjorth

    2013-09-05

    Alveld is a hepatogenous photosensitivity disorder in lambs. The aim of the study was to investigate if alveld affected lambs had a reduced capacity to handle oxidative stress induced from either endogenous and/or exogenous photosensitizers. Serum samples from alveld lambs (n=33) were compared to serum samples from control lambs (n=31) and exposed to a controlled amount of singlet oxygen ((1)O2). The sera from alveld lambs were found to have an impaired ability to deactivate reactive oxygen species (ROS) compared to control sera. A higher degree of initial hemolysis and a higher concentration of the exogenous photosensitizer phytoporphyrin (PP) were detected in alveld sera compared to the controls. The action spectrum for the formation of (1)O2 indicated that PP as well as the endogenous compound protoporphyrin IX (PP IX) may act as in vivo photosensitizers. A relatively high level of iron was detected in pooled serum from alveld lambs that showed a high degree of hemolysis. It was concluded that alveld photosensitivity is likely to be initiated by a photodynamic reaction involving PP and possibly also PP IX followed by a light-independent reaction involving hemoglobin-related products and catalysis by the Fenton reaction. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Zebra chip disease enhances respiration and oxidative stress of potato tubers (Solanum tuberosum L.).

    PubMed

    Kumar, G N Mohan; Knowles, Lisa O; Knowles, N Richard

    2017-06-16

    The physiological phenotype of potato tubers afflicted by zebra chip disease is characterized by increased oxidative stress metabolism and upregulation of systems for its mitigation. Starch catabolism and extensive buildup of reducing sugars render potatoes infected with zebra chip (ZC) pathogen (Candidatus Liberibacter solanacearum) unsuitable for fresh market and processing into chips/fries. Here we show that the disease inflicts considerable oxidative stress, which likely constitutes a substantial sink for metabolic energy, resulting in increased respiration rate of afflicted tubers. In contrast to healthy tubers, tissue from diseased tubers had greater ability to reduce 2,3,5-triphenyl-tetrazolium chloride to formazan, indicating enhanced dehydrogenase activity, probable disease-induced changes in cellular redox potential, and increased respiratory activity. The respiration rate of diseased tubers (cv. Atlantic) was 2.4-fold higher than healthy tubers and this correlated with increased activities of glucose-6-phosphate and 6-phosphogluconate dehydrogenases, key enzymes responsible for synthesis of cytosolic reducing equivalents. Wound-induced NADPH oxidase activity was greater for ZC than healthy tubers, but the resulting superoxide was rapidly catabolized by higher superoxide dismutase activity in ZC tubers. Peroxidase, catalase, glutathione reductase and ascorbate free radical reductase activities were also higher in diseased tubers, as was malondialdehyde, a biomarker of peroxidative damage and oxidative stress. Upregulation of the glutathione-ascorbate pathway is a direct response to (and indicator of) oxidative stress, which consumes reducing equivalents (NADPH) to catabolize reactive oxygen species and maintain cellular redox homeostasis. ZC disease substantially altered the oxidative metabolism of tubers, resulting in a physiological phenotype defined by metabolic changes directed toward mitigating oxidative stress. Paradoxically, the increased

  8. Enhanced transport of phenanthrene and 1-naphthol by colloidal graphene oxide nanoparticles in saturated soil.

    PubMed

    Qi, Zhichong; Hou, Lei; Zhu, Dongqiang; Ji, Rong; Chen, Wei

    2014-09-02

    With the increasing production and use of graphene oxide, the environmental implications of this new carbonaceous nanomaterial have received much attention. In this study, we found that the presence of low concentrations of graphene oxide nanoparticles (GONPs) significantly enhanced the transport of 1-naphthol in a saturated soil, but affected the transport of phenanthrene to a much smaller extent. The much stronger transport-enhancement effect on 1-naphthol was due to the significant desorption hysteresis (both thermodynamically irreversible adsorption and slow desorption kinetics) of GONP-adsorbed 1-naphthol, likely stemmed from the specific polar interactions (e.g., H-bonding) between 1-naphthol and GONPs. Increasing ionic strength or the presence of Cu(II) ion (a complexing cation) generally increased the transport-enhancement capability of GONPs, mainly by increasing the aggregation of GONPs and thus, sequestering adsorbed contaminant molecules. Interestingly, modifying GONPs with Suwannee River humic acid or sodium dodecyl sulfate had little or essentially no effect on the transport-enhancement capability of GONPs, in contrast with the previously reported profound effects of humic acids and surfactants on the transport-enhancement capability of C60 nanoparticles. Overall, the findings indicate that GONPs in the aquatic environment may serve as an effective carrier for certain organic compounds that can interact with GONPs through strong polar interactions.

  9. Enhanced chlorine dioxide decay in the presence of metal oxides: relevance to drinking water distribution systems.

    PubMed

    Liu, Chao; von Gunten, Urs; Croué, Jean-Philippe

    2013-08-06

    Chlorine dioxide (ClO2) decay in the presence of typical metal oxides occurring in distribution systems was investigated. Metal oxides generally enhanced ClO2 decay in a second-order process via three pathways: (1) catalytic disproportionation with equimolar formation of chlorite and chlorate, (2) reaction to chlorite and oxygen, and (3) oxidation of a metal in a reduced form (e.g., cuprous oxide) to a higher oxidation state. Cupric oxide (CuO) and nickel oxide (NiO) showed significantly stronger abilities than goethite (α-FeOOH) to catalyze the ClO2 disproportionation (pathway 1), which predominated at higher initial ClO2 concentrations (56-81 μM). At lower initial ClO2 concentrations (13-31 μM), pathway 2 also contributed. The CuO-enhanced ClO2 decay is a base-assisted reaction with a third-order rate constant of 1.5 × 10(6) M(-2) s(-1) in the presence of 0.1 g L(-1) CuO at 21 ± 1 °C, which is 4-5 orders of magnitude higher than in the absence of CuO. The presence of natural organic matter (NOM) significantly enhanced the formation of chlorite and decreased the ClO2 disproportionation in the CuO-ClO2 system, probably because of a higher reactivity of CuO-activated ClO2 with NOM. Furthermore, a kinetic model was developed to simulate CuO-enhanced ClO2 decay at various pH values. Model simulations that agree well with the experimental data include a pre-equilibrium step with the rapid formation of a complex, namely, CuO-activated Cl2O4. The reaction of this complex with OH(-) is the rate-limiting and pH-dependent step for the overall reaction, producing chlorite and an intermediate that further forms chlorate and oxygen in parallel. These novel findings suggest that the possible ClO2 loss and the formation of chlorite/chlorate should be carefully considered in drinking water distribution systems containing copper pipes.

  10. Light extraction enhancement of organic light-emitting diodes using aluminum zinc oxide embedded anodes.

    PubMed

    Hsu, Ching-Ming; Lin, Bo-Ting; Zeng, Yin-Xing; Lin, Wei-Ming; Wu, Wen-Tuan

    2014-12-15

    Aluminum zinc oxide (AZO) has been embedded onto indium tin oxide (ITO) anode to enhance the light extraction from an organic light-emitting diode (OLED). The embedded AZO provides deflection and scattering interfaces on the newly generated AZO/organics and AZO/ITO interfaces rather than the conventional ITO/organic interface. The current efficiency of AZO embedded OLEDs was enhanced by up to 64%, attributed to the improved light extraction by additionally created reflection and scattering of emitted light on the AZO/ITO interfaces which was roughed in AZO embedding process. The current efficiency was found to increase with the increasing AZO embedded area ratio, but limited by the accompanying increases in haze and electrical resistance of the AZO embedded ITO film.

  11. Enhanced selective oxidation of h-BN nanosheet through a substrate-mediated localized charge effect.

    PubMed

    Mao, Keke; Wu, Xiaojun; Yang, Jinlong

    2017-02-08

    Manipulation of the chemical reactivity of two-dimensional materials is a challenge for advancing various nanotechnologies, ranging from electronics to catalysis. In this study, on the basis of first-principles calculations, we demonstrated that the chemical reactivity of h-BN sheets towards O2 can be significantly enhanced via a metal substrate-mediated charge effect. The chemisorption of O2 molecule on the h-BN sheet deposited on Ni, Co, or Cu substrate were almost spontaneous with negligible energy barrier, distinctly different from that on the freestanding h-BN sheet, which has ultra-high chemical stability. In particular, the enhanced oxidation of h-BN sheet can be confined in the nanoscale region due to the localized electronic states in the h-BN sheet. These findings imply a pathway to selectively oxidize h-BN sheet by patterning the metal substrate.

  12. Enhanced Hot-Carrier Luminescence in Multilayer Reduced Graphene Oxide Nanospheres

    NASA Astrophysics Data System (ADS)

    Chen, Qi; Zhang, Chunfeng; Xue, Fei; Zhou, Yong; Li, Wei; Wang, Ye; Tu, Wenguang; Zou, Zhigang; Wang, Xiaoyong; Xiao, Min

    2013-07-01

    We report a method to promote photoluminescence emission in graphene materials by enhancing carrier scattering instead of directly modifying band structure in multilayer reduced graphene oxide (rGO) nanospheres. We intentionally curl graphene layers to form nanospheres by reducing graphene oxide with spherical polymer templates to manipulate the carrier scattering. These nanospheres produce hot-carrier luminescence with more than ten-fold improvement of emission efficiency as compared to planar nanosheets. With increasing excitation power, hot-carrier luminescence from nanospheres exhibits abnormal spectral redshift with dynamic feature associated to the strengthened electron-phonon coupling. These experimental results can be well understood by considering the screened Coulomb interactions. With increasing carrier density, the reduced screening effect promotes carrier scattering which enhances hot-carrier emission from such multilayer rGO nanospheres. This carrier-scattering scenario is further confirmed by pump-probe measurements.

  13. Water-enhanced catalysis of CO oxidation on free and supported gold nanoclusters.

    PubMed

    Bongiorno, Angelo; Landman, Uzi

    2005-09-02

    The enhancement by water molecules of the catalytic activity of gas-phase and supported gold nanoclusters toward CO oxidation is investigated with first-principles calculations. Coadsorption of H(2)O and O(2) leads to formation of a complex well bound to the gold cluster, even on a defect-free MgO(100) support. Formation of the complex involves partial proton sharing between the adsorbates, that in certain configurations results in proton transfer leading to the appearance of a hydroperoxyl-like complex. The O-O bond is activated, leading to a weakened peroxo or superoxolike state, and consequently the reaction with CO to form CO2 occurs with a small activation barrier of approximately 0.5 eV. A complete catalytic cycle of the water-enhanced CO oxidation is discussed.

  14. Plasmon-enhanced light-driven water oxidation by a dye-sensitized photoanode.

    PubMed

    Wang, Degao; Sherman, Benjamin D; Farnum, Byron H; Sheridan, Matthew V; Marquard, Seth L; Eberhart, Michael S; Dares, Christopher J; Meyer, Thomas J

    2017-09-12

    Dye-sensitized photoelectrosynthesis cells (DSPECs) provide a flexible approach for solar water splitting based on the integration of molecular light absorption and catalysis on oxide electrodes. Recent advances in this area, including the use of core/shell oxide interfacial structures and surface stabilization by atomic layer deposition, have led to improved charge-separation lifetimes and the ability to obtain substantially improved photocurrent densities. Here, we investigate the introduction of Ag nanoparticles into the core/shell structure and report that they greatly enhance light-driven water oxidation at a DSPEC photoanode. Under 1-sun illumination, Ag nanoparticle electrodes achieved high photocurrent densities, surpassing 2 mA cm(-2) with an incident photon-to-current efficiency of 31.8% under 450-nm illumination.

  15. Decavanadate interacts with microsomal NADH oxidation system and enhances cytochrome c reduction.

    PubMed

    Ramasarma, T; Rao, Aparna V S

    2006-01-01

    Oxidation of NADH with accompanying oxygen consumption (NADH:O(2) = 1:1) was observed in the combined presence of metavanadate (MV), decavanadate (DV) and microsomes. Oxygen consumption was negligible in the absence of MV, but NADH was oxidized and DV was reduced to a form of vanadyl-V(IV), colored blue like vanadyl sulfate but differed from it in having a 23-fold higher absorbance at 700 nm. DV can interact with the NADH oxidation system of microsomes as an electron acceptor, in addition to the known ferricyanide and cytochrome c. DV enhances rate of cytochrome c reduction significantly at microM concentrations. These studies indicate potential of DV as a redox intermediate.

  16. Assessment of strontium oxide functionalized graphene nanoflakes for enhanced photocatalytic activity: A density functional theory approach

    SciTech Connect

    Divya, A.; Mathavan, T. Asath, R. Mohamed; Benial, A. Milton Franklin; Archana, J.; Hayakawa, Y.

    2016-05-23

    A series of strontium oxide functionalized graphene nanoflakes were designed and their optoelectronic properties were studied for enhanced photocatalytic activity. The efficiency of designed molecules was studied using various parameters such as HOMO-LUMO energy gap, light harvesting efficiency and exciton binding energy. The computed results show that by increasing the degree of functionalization of strontium oxide leads to lowering the band gap of hydrogen terminated graphene nanoflakes. Furthermore, the study explores the role of strontium oxide functionalization in Frontier Molecular Orbitals, ionization potential, electron affinity, exciton binding energy and light harvesting efficiency of designed molecules. The infrared and Raman spectra were simulated for pure and SrO functionalized graphene nanoflakes. The electron rich and electron deficient regions which are favorable for electrophilic and nucleophilic attacks respectively were analyzed using molecular electrostatic potential surface analysis.

  17. Assessment of strontium oxide functionalized graphene nanoflakes for enhanced photocatalytic activity: A density functional theory approach

    NASA Astrophysics Data System (ADS)

    Divya, A.; Mathavan, T.; Asath, R. Mohamed; Archana, J.; Hayakawa, Y.; Benial, A. Milton Franklin

    2016-05-01

    A series of strontium oxide functionalized graphene nanoflakes were designed and their optoelectronic properties were studied for enhanced photocatalytic activity. The efficiency of designed molecules was studied using various parameters such as HOMO-LUMO energy gap, light harvesting efficiency and exciton binding energy. The computed results show that by increasing the degree of functionalization of strontium oxide leads to lowering the band gap of hydrogen terminated graphene nanoflakes. Furthermore, the study explores the role of strontium oxide functionalization in Frontier Molecular Orbitals, ionization potential, electron affinity, exciton binding energy and light harvesting efficiency of designed molecules. The infrared and Raman spectra were simulated for pure and SrO functionalized graphene nanoflakes. The electron rich and electron deficient regions which are favorable for electrophilic and nucleophilic attacks respectively were analyzed using molecular electrostatic potential surface analysis.

  18. Enhanced oxidative weathering in glaciated mountain catchments: A stabilising feedback on atmospheric carbon dioxide?

    NASA Astrophysics Data System (ADS)

    Horan, K.; Hilton, R. G.; Burton, K. W.; Selby, D. S.; Ottley, C. J.

    2015-12-01

    Mountain belts act as sources of carbon dioxide (CO2) to the atmosphere if physical erosion and exhumation expose rock-derived organic carbon ('petrogenic' organic carbon, OCpetro) to chemical weathering. Estimates suggest 15x1021g of carbon is stored in rocks globally as OCpetro, ~25,000 times the amount of carbon in the pre-industrial atmosphere. Alongside volcanic and metamorphic degassing, OCpetro weathering is thought to be the main source of CO2 to the atmosphere over geological timescales. Erosion in mountain river catchments has been shown to enhance oxidative weathering and CO2 release. However, we still lack studies which quantify this process. In addition, it is not clear how glaciation may impact OCpetro oxidation. In analogy with silicate weathering, large amounts of fine sediment in glacial catchments may enhance oxidative weathering. Here we quantify oxidative weathering in nine catchments draining OCpetro bearing rocks in the western Southern Alps, New Zealand. Using rhenium (Re) as a tracer of oxidative weathering, we develop techniques to precisely measure Re concentration at sub-ppt levels in river waters. Using [Re]water/[Re]rock as a weathering tracer, we estimate that the weathering efficiency in glacial catchments is >4 times that of non-glacial catchments. Combining this with the OCpetro content of rocks and dissolved Re flux, we estimate the CO2 release by OCpetro oxidation. The analysis suggests that non-glacial catchments in the western Southern Alps release similar amounts of CO2 as catchments in Taiwan where erosion rates are comparable. In this mountain belt, the CO2 release does not negate CO2 drawdown by silicate weathering and by riverine transfer of organic matter. Based on our results, we propose that mountain glaciation may greatly enhance OCpetro oxidation rates. Depending on the global fluxes involved, this provides a feedback to damp low atmospheric CO2 levels and global cooling. During glacial periods (low CO2, low global

  19. Enhancing triplet superconductivity by the proximity to a singlet superconductor in oxide heterostructures

    NASA Astrophysics Data System (ADS)

    Horsdal, Mats; Khaliullin, Giniyat; Hyart, Timo; Rosenow, Bernd

    2016-06-01

    We show how in principle a coherent coupling between two superconductors of opposite parity can be realized in a three-layer oxide heterostructure. Due to strong intraionic spin-orbit coupling in the middle layer, singlet Cooper pairs are converted into triplet ones and vice versa. This results in a large enhancement of the triplet superconductivity, persisting well above the native triplet critical temperature.

  20. Chemical derivatization to enhance chemical/oxidative stability of resorcinol-formaldehyde resin

    SciTech Connect

    Hubler, T.

    1996-10-01

    The purpose of this work is to develop modified resorcinol-formaldehyde (R-F) resin with enhanced chemical/oxidative stability in conditions typically encountered in the remediation of radioactive waste tanks. R-F resin is a regenerable organic ion-exchanger developed at Savannah River Technology Center that is being considered for use in the selective removal of radioactive cesium from alkaline waste tank supernates at both the Hanford and Savannah River sites.

  1. Use of bias sputtering to enhance decoupling in oxide composite perpendicular recording media

    SciTech Connect

    Lee, Hwan-Soo; Bain, James A.; Laughlin, David E.

    2007-06-18

    The effects of substrate bias on two types of oxide composite perpendicular recording media CoCrPt-SiO{sub 2} and FePt-MgO were investigated. The use of substrate bias greatly modified the thin film microstructure and resulted in the enhanced grain decoupling in the films. The growth characteristics due to preferential resputtering were interpreted to arise mainly from weak surface bonding to the growing films for nontextured growth, combined with strong cohesion for the textured growth.

  2. Enhanced methanol electro-oxidation reaction on Pt-CoOx/MWCNTs hybrid electro-catalyst

    NASA Astrophysics Data System (ADS)

    Nouralishahi, Amideddin; Rashidi, Ali Morad; Mortazavi, Yadollah; Khodadadi, Abbas Ali; Choolaei, Mohammadmehdi

    2015-04-01

    The electro-catalytic behavior of Pt-CoOx/MWCNTs in methanol electro-oxidation reaction (MOR) is investigated and compared to that of Pt/MWCNTs. The electro-catalysts were synthesized by an impregnation method using NaBH4 as the reducing agent. The morphological and physical characteristics of samples are examined by XRD, TEM, ICP and EDS techniques. In the presence of CoOx, Pt nanoparticles were highly distributed on the support with an average particle size of 2 nm, an obvious decrease from 5.1 nm for Pt/MWCNTs. Cyclic voltammetry, CO-stripping, Chronoamperometry, and electrochemical impedance spectroscopy (EIS) measurements are used to study the electrochemical behavior of the electro-catalysts. The results revealed a considerable enhancement in the oxidation kinetics of COads on Pt active sites by the participation of CoOx. Compared to Pt/MWCNTs, Pt-CoOx/MWCNTs sample has a larger electrochemical active surface area (ECSA) and higher electro-catalytic activity and stability toward methanol electro-oxidation. According to the results of cyclic voltammetry, the forward anodic peak current density enhances more than 89% at the optimum atomic ratio of Pt:Co = 2:1. Furthermore, inclusion of cobalt oxide species causes the onset potential of methanol electro-oxidation reaction to shift 84 mV to negative values compared to that on Pt/MWCNTs. Based on EIS data, dehydrogenation of methanol is the rate-determining step of MOR on both Pt/MWCNTs and Pt-CoOx/MWCNTs, at small overpotentials. However, at higher overpotentials, the oxidation of adsorbed oxygen-containing groups controls the total rate of MOR process.

  3. Supplementation with vitamin A enhances oxidative stress in the lungs of rats submitted to aerobic exercise.

    PubMed

    Gasparotto, Juciano; Petiz, Lyvia Lintzmaier; Girardi, Carolina Saibro; Bortolin, Rafael Calixto; de Vargas, Amanda Rodrigues; Henkin, Bernardo Saldanha; Chaves, Paloma Rodrigues; Roncato, Sabrina; Matté, Cristiane; Zanotto-Filho, Alfeu; Moreira, José Cláudio Fonseca; Gelain, Daniel Pens

    2015-12-01

    Exercise training induces reactive oxygen species production and low levels of oxidative damage, which are required for induction of antioxidant defenses and tissue adaptation. This process is physiological and essential to improve physical conditioning and performance. During exercise, endogenous antioxidants are recruited to prevent excessive oxidative stress, demanding appropriate intake of antioxidants from diet or supplements; in this context, the search for vitamin supplements that enhance the antioxidant defenses and improve exercise performance has been continuously increasing. On the other hand, excess of antioxidants may hinder the pro-oxidant signals necessary for this process of adaptation. The aim of this study was to investigate the effects of vitamin A supplementation (2000 IU/kg, oral) upon oxidative stress and parameters of pro-inflammatory signaling in lungs of rats submitted to aerobic exercise (swimming protocol). When combined with exercise, vitamin A inhibited biochemical parameters of adaptation/conditioning by attenuating exercise-induced antioxidant enzymes (superoxide dismutase and glutathione peroxidase) and decreasing the content of the receptor for advanced glycation end-products. Increased oxidative damage to proteins (carbonylation) and lipids (lipoperoxidation) was also observed in these animals. In sedentary animals, vitamin A decreased superoxide dismutase and increased lipoperoxidation. Vitamin A also enhanced the levels of tumor necrosis factor alpha and decreased interleukin-10, effects partially reversed by aerobic training. Taken together, the results presented herein point to negative effects associated with vitamin A supplementation at the specific dose here used upon oxidative stress and pro-inflammatory cytokines in lung tissues of rats submitted to aerobic exercise.

  4. Perm1 enhances mitochondrial biogenesis, oxidative capacity, and fatigue resistance in adult skeletal muscle

    PubMed Central

    Cho, Yoshitake; Hazen, Bethany C.; Gandra, Paulo G.; Ward, Samuel R.; Schenk, Simon; Russell, Aaron P.; Kralli, Anastasia

    2016-01-01

    Skeletal muscle mitochondrial content and oxidative capacity are important determinants of muscle function and whole-body health. Mitochondrial content and function are enhanced by endurance exercise and impaired in states or diseases where muscle function is compromised, such as myopathies, muscular dystrophies, neuromuscular diseases, and age-related muscle atrophy. Hence, elucidating the mechanisms that control muscle mitochondrial content and oxidative function can provide new insights into states and diseases that affect muscle health. In past studies, we identified Perm1 (PPARGC1- and ESRR-induced regulator, muscle 1) as a gene induced by endurance exercise in skeletal muscle, and regulating mitochondrial oxidative function in cultured myotubes. The capacity of Perm1 to regulate muscle mitochondrial content and function in vivo is not yet known. In this study, we use adeno-associated viral (AAV) vectors to increase Perm1 expression in skeletal muscles of 4-wk-old mice. Compared to control vector, AAV1-Perm1 leads to significant increases in mitochondrial content and oxidative capacity (by 40–80%). Moreover, AAV1-Perm1–transduced muscles show increased capillary density and resistance to fatigue (by 33 and 31%, respectively), without prominent changes in fiber-type composition. These findings suggest that Perm1 selectively regulates mitochondrial biogenesis and oxidative function, and implicate Perm1 in muscle adaptations that also occur in response to endurance exercise.—Cho, Y., Hazen, B. C., Gandra, P. G., Ward, S. R., Schenk, S., Russell, A. P., Kralli, A. Perm1 enhances mitochondrial biogenesis, oxidative capacity, and fatigue resistance in adult skeletal muscle. PMID:26481306

  5. Light-Enhanced Antibacterial Activity of Graphene Oxide, Mainly via Accelerated Electron Transfer.

    PubMed

    Chong, Yu; Ge, Cuicui; Fang, Ge; Wu, Renfei; Zhang, He; Chai, Zhifang; Chen, Chunying; Yin, Jun-Jie

    2017-09-05

    Before graphene derivatives can be exploited as next-generation antimicrobials, we must understand their behavior under environmental conditions. Here, we demonstrate how exposure to simulated sunlight significantly enhances the antibacterial activity of graphene oxide (GO) and reveal the underlying mechanism. Our measurements of reactive oxygen species (ROS) showed that only singlet oxygen ((1)O2) is generated by GO exposed to simulated sunlight, which contributes only slightly to the oxidation of antioxidant biomolecules. Unexpectedly, we find the main cause of oxidation is light-induced electron-hole pairs generated on the surface of GO. These light-induced electrons promote the reduction of GO, introducing additional carbon-centered free radicals that may also enhance the antibacterial activities of GO. We conclude that GO-mediated oxidative stress mainly is ROS-independent; simulated sunlight accelerates the transfer of electrons from antioxidant biomolecules to GO, thereby destroying bacterial antioxidant systems and causing the reduction of GO. Our insights will help support the development of graphene for antibacterial applications.

  6. Docosahexaenoic Acid Induces Oxidative DNA Damage and Apoptosis, and Enhances the Chemosensitivity of Cancer Cells

    PubMed Central

    Song, Eun Ah; Kim, Hyeyoung

    2016-01-01

    The human diet contains low amounts of ω-3 polyunsaturated fatty acids (PUFAs) and high amounts of ω-6 PUFAs, which has been reported to contribute to the incidence of cancer. Epidemiological studies have shown that a high consumption of fish oil or ω-3 PUFAs reduced the risk of colon, pancreatic, and endometrial cancers. The ω-3 PUFA, docosahexaenoic acid (DHA), shows anticancer activity by inducing apoptosis of some human cancer cells without toxicity against normal cells. DHA induces oxidative stress and oxidative DNA adduct formation by depleting intracellular glutathione (GSH) and decreasing the mitochondrial function of cancer cells. Oxidative DNA damage and DNA strand breaks activate DNA damage responses to repair the damaged DNA. However, excessive DNA damage beyond the capacity of the DNA repair processes may initiate apoptotic signaling pathways and cell cycle arrest in cancer cells. DHA shows a variable inhibitory effect on cancer cell growth depending on the cells’ molecular properties and degree of malignancy. It has been shown to affect DNA repair processes including DNA-dependent protein kinases and mismatch repair in cancer cells. Moreover, DHA enhanced the efficacy of anticancer drugs by increasing drug uptake and suppressing survival pathways in cancer cells. In this review, DHA-induced oxidative DNA damage, apoptotic signaling, and enhancement of chemosensitivity in cancer cells will be discussed based on recent studies. PMID:27527148

  7. Treatment of obstructive sleep apnoea leads to enhanced pulmonary vascular nitric oxide release.

    PubMed

    Lattimore, Jo-Dee L; Wilcox, Ian; Adams, Mark R; Kilian, Jens G; Celermajer, David S

    2008-05-23

    Obstructive sleep apnoea (OSA) is associated with pulmonary hypertension, however neither the pathogenesis of pulmonary vascular disease nor the effect of successful treatment of OSA on pulmonary vascular physiology has been characterised. Seven subjects aged 52 (range 36-63) years with moderate to severe obstructive sleep apnoea (apnoea-hypopnoea index>15/h) had detailed pulmonary vascular reactivity studies, before and after 3 months of successful treatment with nasal continuous positive airways pressure (CPAP). On both occasions, we measured pulmonary pressure, flow velocity, flow and resistance, at baseline and in response to acetylcholine (an endothelium-dependent dilator), sodium nitroprusside (an endothelium-independent dilator), l-NMMA (an antagonist of nitric oxide synthesis) and l-Arginine (the substrate of nitric oxide). At baseline, pulmonary flow increased in response to acetylcholine and nitroprusside and fell in response to l-NMMA. Following CPAP treatment, the decrease in flow to l-NMMA was significantly greater (to 62+/-6% of control value vs 85+/-6% of pre-treatment; p=0.01), consistent with enhanced basal release of nitric oxide. The acetylcholine response tended to be greater after treatment (174+/-26% of control vs 147+/-12% of pre-CPAP, p=0.22), however the nitroprusside response was unchanged. Successful treatment of obstructive sleep apnoeic episodes in sleep results in enhanced nitric oxide release by the pulmonary microvascular circulation.

  8. Docosahexaenoic Acid Induces Oxidative DNA Damage and Apoptosis, and Enhances the Chemosensitivity of Cancer Cells.

    PubMed

    Song, Eun Ah; Kim, Hyeyoung

    2016-08-03

    The human diet contains low amounts of ω-3 polyunsaturated fatty acids (PUFAs) and high amounts of ω-6 PUFAs, which has been reported to contribute to the incidence of cancer. Epidemiological studies have shown that a high consumption of fish oil or ω-3 PUFAs reduced the risk of colon, pancreatic, and endometrial cancers. The ω-3 PUFA, docosahexaenoic acid (DHA), shows anticancer activity by inducing apoptosis of some human cancer cells without toxicity against normal cells. DHA induces oxidative stress and oxidative DNA adduct formation by depleting intracellular glutathione (GSH) and decreasing the mitochondrial function of cancer cells. Oxidative DNA damage and DNA strand breaks activate DNA damage responses to repair the damaged DNA. However, excessive DNA damage beyond the capacity of the DNA repair processes may initiate apoptotic signaling pathways and cell cycle arrest in cancer cells. DHA shows a variable inhibitory effect on cancer cell growth depending on the cells' molecular properties and degree of malignancy. It has been shown to affect DNA repair processes including DNA-dependent protein kinases and mismatch repair in cancer cells. Moreover, DHA enhanced the efficacy of anticancer drugs by increasing drug uptake and suppressing survival pathways in cancer cells. In this review, DHA-induced oxidative DNA damage, apoptotic signaling, and enhancement of chemosensitivity in cancer cells will be discussed based on recent studies.

  9. Enhancement of Ferromagnetism in Nonmagnetic Metal Oxide Nanoparticles by Facet Engineering.

    PubMed

    Long, Liyuan; Xiong, Shijie; Meng, Ming; Liu, Lizhe; Zhang, Jinlei; Wu, Xinglong; Chu, Paul K

    2017-02-01

    Ferromagnetism in semiconducting metal oxide nanoparticles has been intensively investigated due to their potential applications in spintronics, information storage, and biomedicine. Ferromagnetism can be produced in nonmagnetic metal oxide nanoparticles by a variety of methods or factors, but the saturated magnetization is typically of the order of 10(-4) emu g(-1) and too small to be useful in practice. In this work, it is demonstrated theoretically and experimentally that stronger ferromagnetism can be achieved in undoped nonmagnetic metal oxide semiconductors by exposing some specific polar crystal facets with carvings of special bonds via the interaction with underlying vacancies. In2 O3 microcubes with completely enclosed {001} polar facets show two orders of magnitude enhancement at room temperature compared to nanoparticles with an irregular morphology. The surface magnetic domains on the {001} facets account for the significantly enhanced ferromagnetism. The technique and concept described here can be extended to other types of metal oxide nanostructures to spur their application to spintronics. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Erythropoietin enhances whole body lipid oxidation during prolonged exercise in humans.

    PubMed

    Caillaud, Corinne; Connes, Philippe; Ben Saad, Helmi; Mercier, Jacques

    2015-03-01

    Animal studies have suggested that erythropoietin, besides its well-known hematopoietic effects, can modulate metabolism and prevent fat accumulation. We investigated the effects of repeated injections of recombinant human erythropoietin (EPO) on the balance of substrate oxidation during aerobic exercise in humans. Twelve healthy aerobically trained males received subcutaneously either moderate dose of EPO (50 U/kg, EPO) or saline injections (NaCl 0.9 %, control) three times a week for 4 weeks. Body weight, % fat, maximal aerobic capacity, and substrate utilization during exercise were assessed before and after treatment, while hemoglobin and hematocrit were monitored regularly during the treatment. Carbohydrate and fat oxidation were evaluated via indirect calorimetry, during a submaximal exercise performed at 75 % of the participants' maximal aerobic capacity (V̇(O2max)) for 60 min. Results showed that 4 weeks of EPO treatment significantly enhanced fat oxidation (+56 % in EPO versus -9 % in control) during exercise, independent of its effects on hematological parameters or V̇(O2max). This study shows that EPO can modulate substrate utilization during exercise, leading to enhanced fat utilization and lower use of carbohydrates. This opens new research directions exploring whether systemic EPO levels, in physiological conditions, participate to the modulation of fat oxidation.

  11. Enhanced organic photovoltaic properties via structural modifications in PEDOT:PSS due to graphene oxide doping

    SciTech Connect

    Goutham, Raj P.; Sandhya, Rani V.; Kanwat, Anil; Jang, Jin

    2016-02-15

    Highlights: • Graphene oxide(GO) blended with PEDOT:PSS is used as HTL for PTB7:PCBM BHJ solar cells. • Increase in conductivity due to structural alterations in PEDOT:PSS by GO addition. • The structural alterations are reaveled under Raman spectroscopy, XPS and AFM. • PEDOT:PSS changed to extended coil due to addition of GO to PEDOT:PSS. • Enhanced conductivity after GO addition to PEDOT:PSS resulted in enhanced PCE. - Abstract: Poly(3,4-thylenedioxythiophene):poly(styrene sulfonate), PEDOT:PSS is a well-known conductive polymer for hole transport in organic devices, the properties of which can be enhanced by doping. Common dopants are metal oxides and nanoparticles. In this study, addition of graphene oxide (GO) to PEDOT:PSS as a dopant is addressed in organic photovoltaics (OPVs). With GO doping, electrical conductivity and transport properties of PEDOT:PSS increases due to structural alterations in the presence of −COOH and −OH functional groups in GO. These structural alterations have been revealed under detailed study of Raman spectra, X-ray photoelectron spectroscopy (XPS) analysis, Topographical and conductive Atom force microscopy (AFM/C-AFM) mapping. OPVs fabricated using PEDOT:PSS: GO (5:1) as a hole transport layer (HTL) exhibited a power conversion efficiency (PCE) of 7.68%, which was higher than the 7.01% that was obtained for the OPVs using pristine PEDOT:PSS.

  12. Sulindac Enhances the Killing of Cancer Cells Exposed to Oxidative Stress

    PubMed Central

    Marchetti, Maria; Resnick, Lionel; Gamliel, Edna; Kesaraju, Shailaja; Weissbach, Herbert; Binninger, David

    2009-01-01

    Background Sulindac is an FDA-approved non-steroidal anti-inflammatory drug (NSAID) that affects prostaglandin production by inhibiting cyclooxygenases (COX) 1 and 2. Sulindac has also been of interest for more than decade as a chemopreventive for adenomatous colorectal polyps and colon cancer. Principal Findings Pretreatment of human colon and lung cancer cells with sulindac enhances killing by an oxidizing agent such as tert-butyl hydroperoxide (TBHP) or hydrogen peroxide. This effect does not involve cyclooxygenase (COX) inhibition. However, under the conditions used, there is a significant increase in reactive oxygen species (ROS) within the cancer cells and a loss of mitochondrial membrane potential, suggesting that cell death is due to apoptosis, which was confirmed by Tunel assay. In contrast, this enhanced killing was not observed with normal lung or colon cells. Significance These results indicate that normal and cancer cells handle oxidative stress in different ways and sulindac can enhance this difference. The combination of sulindac and an oxidizing agent could have therapeutic value. PMID:19503837

  13. Histopathological and bacterial study of skin and gill of grass carp, Ceteopharyngodon idella, (Valenciennes 1844) exposed to copper sulfate and potassium permanganate.

    PubMed

    Jooyandeh, Fatemeh; Sadeghpour, Ali; Khara, Hossein; Pajand, Zabihollah

    2016-09-01

    The gill histology and bacterial load of skin of the grass carp juveniles were investigated in relation to various concentrations of copper sulfate and potassium permanganate. For this purpose, the sublethal doses were determined after a pre-test and then the experiment was done in five treatments (for copper sulfate: 1, 1.94, 3.71, 7.07 and 15 mg/l and for potassium permanganate: 0.25, 0.52, 1.91, 2.27 and 5 mg/l) with three replicates inside the glass aquaria. Also, one group without disinfecting product was considered as control for each experiment. The microbial and histopathological investigations were done after 96 h exposure. According to results, the lowest bacterial load (CFU/g) of skin was observed in 15 mg/l copper sulfate treatment and 0.25 mg/l potassium permanganate treatment (P < 0.05). Also, the histological investigation showed a range of histopathological alternations in gills tissue including lamellar necrosis, hyperplasia, lamellar adhesion, haemorrhage, clubbing of gill lamellae. The severity of these alternations increased with increasing of the doses of the copper sulfate and potassium permanganate. In this regard, the highest histological damages were observed in 15 mg/l copper sulfate and 5 mg/l potassium permanganate respectively. Our results showed that low dosage of potassium permanganate has best effect on reducing of bacterial load of skin with lowest adverse effects on gill tissue.

  14. Specific detection of pathological three-repeat tau after pretreatment with potassium permanganate and oxalic acid in PSP/CBD brains.

    PubMed

    Uchihara, Toshiki; Nakamura, Ayako; Shibuya, Katsuhiko; Yagishita, Saburo

    2011-03-01

    Immunohistochemisty with RD3, a monoclonal antibody specific for three-repeat (3R) tau, is sometimes hampered by diffuse neuronal staining on formalin-fixed, paraffin-embedded sections pretreated with formic acid and heating. Additional pretreatment with potassium permanganate followed by oxalic acid completely eliminated this diffuse RD3-immunoreactivity (IR) in neurons. Furthermore, this additional pretreatment uniformly enhanced RD3-IR, as well as RD4-IR, a monoclonal antibody specific for four-repeat (4R) tau, on pathological deposits with tau IR. This enhanced sensitivity and specificity may allow more reliable identification of 3R and 4R tau in pathological deposits, which may be variable dependent on disease and regions. Cerebral cortex and midbrain from 8 patients [5 progressive supranuclear palsy (PSP) and 3 corticobasal degeneration (CBD)] were screened for RD3- and RD4-IR with this improved procedure. In addition to RD4-positive structures found both in cerebral cortex and brainstem, RD3-positive neurofibrillary tangles (NFTs) were also found in midbrain in 7 of these 8 cases but not in the cortex. Multi-labeling study demonstrated that most of RD3-negative neurons were positive for RD4. This reliable demonstration of pathological 3R tau deposits in the brainstem of PSP/CBD, so far presumably characterized by deposition of 4R tau, is useful to map tau-positive lesions according to their biochemical composition.

  15. Flame oxidation of stainless steel felt enhances anodic biofilm formation and current output in bioelectrochemical systems.

    PubMed

    Guo, Kun; Donose, Bogdan C; Soeriyadi, Alexander H; Prévoteau, Antonin; Patil, Sunil A; Freguia, Stefano; Gooding, J Justin; Rabaey, Korneel

    2014-06-17

    Stainless steel (SS) can be an attractive material to create large electrodes for microbial bioelectrochemical systems (BESs), due to its low cost and high conductivity. However, poor biocompatibility limits its successful application today. Here we report a simple and effective method to make SS electrodes biocompatible by means of flame oxidation. Physicochemical characterization of electrode surface indicated that iron oxide nanoparticles (IONPs) were generated in situ on an SS felt surface by flame oxidation. IONPs-coating dramatically enhanced the biocompatibility of SS felt and consequently resulted in a robust electroactive biofilm formation at its surface in BESs. The maximum current densities reached at IONPs-coated SS felt electrodes were 16.5 times and 4.8 times higher than the untreated SS felts and carbon felts, respectively. Furthermore, the maximum current density achieved with the IONPs-coated SS felt (1.92 mA/cm(2), 27.42 mA/cm(3)) is one of the highest current densities reported thus far. These results demonstrate for the first time that flame oxidized SS felts could be a good alternative to carbon-based electrodes for achieving high current densities in BESs. Most importantly, high conductivity, excellent mechanical strength, strong chemical stability, large specific surface area, and comparatively low cost of flame oxidized SS felts offer exciting opportunities for scaling-up of the anodes for BESs.

  16. Chemically Driven Enhancement of Oxygen Reduction Electrocatalysis in Supported Perovskite Oxides.

    PubMed

    Lee, Daehee; Tan, Jeiwan; Chae, Keun Hwa; Jeong, Beomgyun; Soon, Aloysius; Ahn, Sung-Jin; Kim, Joosun; Moon, Jooho

    2017-01-05

    Perovskite oxides have the capacity to efficiently catalyze the oxygen reduction reaction (ORR), which is of fundamental importance for electrochemical energy conversion. While the perovskite catalysts have been generally utilized with a support, the role of the supports, regarded as inert toward the ORR, has been emphasized mostly in terms of the thermal stability of the catalyst system and as an ancillary transport channel for oxygen ions during the ORR. We demonstrate a novel approach to improving the catalytic activity of perovskite oxides for solid oxide fuel cells by controlling the oxygen-ion conducting oxide supports. Catalytic activities of (La0.8Sr0.2)0.95MnO3 perovskite thin-film placed on different oxide supports are characterized by electrochemical impedance spectroscopy and X-ray absorption spectroscopy. These analyses confirm that the strong atomic orbital interactions between the support and the perovskite catalyst enhance the surface exchange kinetics by ∼2.4 times, in turn, improving the overall ORR activity.

  17. Fabrication of protective over layer for enhanced thermal stability of zinc oxide based TCO films

    NASA Astrophysics Data System (ADS)

    Ravichandran, K.; Ravikumar, P.; Sakthivel, B.

    2013-12-01

    To prevent the loss of oxygen vacancies in aluminium doped zinc oxide (AZO) thin films at high temperature process, and to enhance the thermal stability a protective tin oxide (TO) over layer has been realized. To investigate the protective nature of doped tin oxide layer, fluorine doped tin oxide (FTO) and antimony doped tin oxide (ATO) layers have also been coated on AZO layer. Then, to confirm its stability of opto-electrical properties under high temperature process, structural, optical and electrical studies of AZO single layer, TO/AZO, FTO/AZO and ATO/AZO double layered films were carried out before and after annealing and the results are reported. The XRD results showed that the crystalline nature of double layered films remains unchanged, even after the heat treatment. The UV results depicted that, in all the double layer films the transmission spectra remain unchanged or changed negligibly after annealing, indicating the thermal stability of double layered films. The photoluminescence results also strongly supported the improvement in the thermal stability of double layered films. The electrical studies suggested that the double layered films exhibited better electrical resistivity with bare AZO films.

  18. Perm1 enhances mitochondrial biogenesis, oxidative capacity, and fatigue resistance in adult skeletal muscle.

    PubMed

    Cho, Yoshitake; Hazen, Bethany C; Gandra, Paulo G; Ward, Samuel R; Schenk, Simon; Russell, Aaron P; Kralli, Anastasia

    2016-02-01

    Skeletal muscle mitochondrial content and oxidative capacity are important determinants of muscle function and whole-body health. Mitochondrial content and function are enhanced by endurance exercise and impaired in states or diseases where muscle function is compromised, such as myopathies, muscular dystrophies, neuromuscular diseases, and age-related muscle atrophy. Hence, elucidating the mechanisms that control muscle mitochondrial content and oxidative function can provide new insights into states and diseases that affect muscle health. In past studies, we identified Perm1 (PPARGC1- and ESRR-induced regulator, muscle 1) as a gene induced by endurance exercise in skeletal muscle, and regulating mitochondrial oxidative function in cultured myotubes. The capacity of Perm1 to regulate muscle mitochondrial content and function in vivo is not yet known. In this study, we use adeno-associated viral (AAV) vectors to increase Perm1 expression in skeletal muscles of 4-wk-old mice. Compared to control vector, AAV1-Perm1 leads to significant increases in mitochondrial content and oxidative capacity (by 40-80%). Moreover, AAV1-Perm1-transduced muscles show increased capillary density and resistance to fatigue (by 33 and 31%, respectively), without prominent changes in fiber-type composition. These findings suggest that Perm1 selectively regulates mitochondrial biogenesis and oxidative function, and implicate Perm1 in muscle adaptations that also occur in response to endurance exercise. © FASEB.

  19. Impact of chemical oxidation on soil quality.

    PubMed

    Sirguey, Catherine; de Souza e Silva, Paula Tereza; Schwartz, Christophe; Simonnot, Marie-Odile

    2008-05-01

    Oxidation treatment helps to reduce the polycyclic aromatic hydrocarbon (PAH) load in contaminated soils but it may also have an effect on the soil quality. The impact of permanganate and Fenton oxidation on soil quality is investigated. Soil quality is restricted here to the potential for plant growth. Soil samples were collected from an agricultural field (S1) and a former coking plant (S4). Agricultural soil was spiked with phenanthrene (PHE) and pyrene (PYR) at two concentrations (S2: 700 mg PHE kg(-1), S3: 700 mg PHE kg(-1) and 2100 mg PYR kg(-1)). Soils were treated with both oxidation processes, and analyzed for PAHs and a set of agronomic parameters. A plant germination and growth test was run with rye-grass on treated soils. Results showed that both treatments produced the expected reduction of PAH concentration (from 64% to 97%). Besides, a significant loss of organic C and N, and strong changes in available nutrients were observed. Permanganate treatment increased the specific surface area and the cation exchange capacity in relation to manganese dioxide precipitation, and produced a rise in pH. Fenton oxidation decreased soil pH and increased the water retention capacity. Plant growth was negatively affected by permanganate, related to lower soil permeability and aeration. Both treatments had an effect on soil properties but Fenton oxidation appeared to be more compatible with revegetation.

  20. Surface- and tip-enhanced Raman spectroscopy reveals spin-waves in iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Rodriguez, Raul D.; Sheremet, Evgeniya; Deckert-Gaudig, Tanja; Chaneac, Corinne; Hietschold, Michael; Deckert, Volker; Zahn, Dietrich R. T.

    2015-05-01

    Nanomaterials have the remarkable characteristic of displaying physical properties different from their bulk counterparts. An additional degree of complexity and functionality arises when oxide nanoparticles interact with metallic nanostructures. In this context the Raman spectra due to plasmonic enhancement of iron oxide nanocrystals are here reported showing the activation of spin-waves. Iron oxide nanoparticles on gold and silver tips are found to display a band around 1584 cm-1 attributed to a spin-wave magnon mode. This magnon mode is not observed for nanoparticles deposited on silicon (111) or on glass substrates. Metal-nanoparticle interaction and the strongly localized electromagnetic field contribute to the appearance of this mode. The localized excitation that generates this mode is confirmed by tip-enhanced Raman spectroscopy (TERS). The appearance of the spin-waves only when the TERS tip is in close proximity to a nanocrystal edge suggests that the coupling of a localized plasmon with spin-waves arises due to broken symmetry at the nanoparticle border and the additional electric field confinement. Beyond phonon confinement effects previously reported in similar systems, this work offers significant insights on the plasmon-assisted generation and detection of spin-waves optically induced.Nanomaterials have the remarkable characteristic of displaying physical properties different from their bulk counterparts. An additional degree of complexity and functionality arises when oxide nanoparticles interact with metallic nanostructures. In this context the Raman spectra due to plasmonic enhancement of iron oxide nanocrystals are here reported showing the activation of spin-waves. Iron oxide nanoparticles on gold and silver tips are found to display a band around 1584 cm-1 attributed to a spin-wave magnon mode. This magnon mode is not observed for nanoparticles deposited on silicon (111) or on glass substrates. Metal-nanoparticle interaction and the strongly

  1. Enhanced Oxidation of Isoprene and Monoterpenes in High and Low NOx Conditions

    NASA Astrophysics Data System (ADS)

    Tokarek, T. W.; Gilman, J.; Lerner, B. M.; Koss, A.; Yuan, B.; Taha, Y. M.; Osthoff, H. D.; Warneke, C.; De Gouw, J. A.

    2015-12-01

    In the troposphere, the photochemical oxidation of volatile organic compounds (VOCs) is primarily initiated by their reactions with the hydroxyl radical (OH) which yields peroxy radicals (HO2 and RO2). Concentrations of OH and the rates of VOC oxidation depend on the efficiency of peroxy radical recycling to OH. Radical recycling mainly occurs through reaction of HO2 with NO to produce NO2 and, ultimately, ozone (O3). Hence, the rate of VOC oxidation is dependent on NOx (=NO+NO2) concentration. The Shale Oil and Natural Gas Nexus (SONGNEX) campaign was conducted from March 17 to April 29, 2015 with the main goal of identifying and quantifying industrial sources of pollutants throughout the United States, in particular those associated with the production of oil and natural gas. In this work, a case study of biogenic VOC oxidation within and outside a power plant plume in the Haynesville basin near the border of Texas and Louisiana is presented. Isoprene, monoterpenes and their oxides were measured by H3O+ chemical ionization mass spectrometry (H3O+ CIMS) in high time resolution (1 s). Further, an improved Whole Air Sampler (iWAS) was used to collect samples for post-flight analysis by gas chromatography mass spectrometric detection (GC-MS) and yielded speciated quantification of biogenic VOCs. The monoterpene oxide to monoterpene ratio follows the spatial extent of the plume as judged by another tracer (NOx), tracking the enhancement of oxidation rates by NOx. The observations are rationalized with the aid of box modeling using the Master Chemical Mechanism (MCM).

  2. Enhanced Evaporation Strength through Fast Water Permeation in Graphene-Oxide Deposition.

    PubMed

    Tong, Wei Li; Ong, Wee-Jun; Chai, Siang-Piao; Tan, Ming K; Hung, Yew Mun

    2015-06-23

    The unique characteristic of fast water permeation in laminated graphene oxide (GO) sheets has facilitated the development of ultrathin and ultrafast nanofiltration membranes. Here we report the application of fast water permeation property of immersed GO deposition for enhancing the performance of a GO/water nanofluid charged two-phase closed thermosyphon (TPCT). By benchmarking its performance against a silver oxide/water nanofluid charged TPCT, the enhancement of evaporation strength is found to be essentially attributed to the fast water permeation property of GO deposition instead of the enhanced surface wettability of the deposited layer. The expansion of interlayer distance between the graphitic planes of GO deposited layer enables intercalation of bilayer water for fast water permeation. The capillary force attributed to the frictionless interaction between the atomically smooth, hydrophobic carbon structures and the well-ordered hydrogen bonds of water molecules is sufficiently strong to overcome the gravitational force. As a result, a thin water film is formed on the GO deposited layers, inducing filmwise evaporation which is more effective than its interfacial counterpart, appreciably enhanced the overall performance of TPCT. This study paves the way for a promising start of employing the fast water permeation property of GO in thermal applications.

  3. Enhanced Evaporation Strength through Fast Water Permeation in Graphene-Oxide Deposition

    NASA Astrophysics Data System (ADS)

    Li Tong, Wei; Ong, Wee-Jun; Chai, Siang-Piao; Tan, Ming K.; Mun Hung, Yew

    2015-06-01

    The unique characteristic of fast water permeation in laminated graphene oxide (GO) sheets has facilitated the development of ultrathin and ultrafast nanofiltration membranes. Here we report the application of fast water permeation property of immersed GO deposition for enhancing the performance of a GO/water nanofluid charged two-phase closed thermosyphon (TPCT). By benchmarking its performance against a silver oxide/water nanofluid charged TPCT, the enhancement of evaporation strength is found to be essentially attributed to the fast water permeation property of GO deposition instead of the enhanced surface wettability of the deposited layer. The expansion of interlayer distance between the graphitic planes of GO deposited layer enables intercalation of bilayer water for fast water permeation. The capillary force attributed to the frictionless interaction between the atomically smooth, hydrophobic carbon structures and the well-ordered hydrogen bonds of water molecules is sufficiently strong to overcome the gravitational force. As a result, a thin water film is formed on the GO deposited layers, inducing filmwise evaporation which is more effective than its interfacial counterpart, appreciably enhanced the overall performance of TPCT. This study paves the way for a promising start of employing the fast water permeation property of GO in thermal applications.

  4. Enhanced Evaporation Strength through Fast Water Permeation in Graphene-Oxide Deposition

    PubMed Central

    Li Tong, Wei; Ong, Wee-Jun; Chai, Siang-Piao; Tan, Ming K.; Mun Hung, Yew

    2015-01-01

    The unique characteristic of fast water permeation in laminated graphene oxide (GO) sheets has facilitated the development of ultrathin and ultrafast nanofiltration membranes. Here we report the application of fast water permeation property of immersed GO deposition for enhancing the performance of a GO/water nanofluid charged two-phase closed thermosyphon (TPCT). By benchmarking its performance against a silver oxide/water nanofluid charged TPCT, the enhancement of evaporation strength is found to be essentially attributed to the fast water permeation property of GO deposition instead of the enhanced surface wettability of the deposited layer. The expansion of interlayer distance between the graphitic planes of GO deposited layer enables intercalation of bilayer water for fast water permeation. The capillary force attributed to the frictionless interaction between the atomically smooth, hydrophobic carbon structures and the well-ordered hydrogen bonds of water molecules is sufficiently strong to overcome the gravitational force. As a result, a thin water film is formed on the GO deposited layers, inducing filmwise evaporation which is more effective than its interfacial counterpart, appreciably enhanced the overall performance of TPCT. This study paves the way for a promising start of employing the fast water permeation property of GO in thermal applications. PMID:26100977

  5. Palladium networks decorated by cuprous oxide for remarkably enhanced electrocatalytic activity of methanol oxidation reaction with high CO-tolerance

    NASA Astrophysics Data System (ADS)

    Ji, Yuanyuan; Ying, Ye; Pan, Yuxia; Li, Mengzhu; Guo, Xiaoyu; Wu, Yiping; Wen, Ying; Yang, Haifeng

    2016-10-01

    The CuO nanorods (NRs) are prepared with the help of inositol hexakisphosphate which serves as a binding agent and stabilizer. We have successfully fabricated Cu2O-decorated palladium networks (Cu2O/Pd Networks) by using such CuO NRs as reaction beds. Transmission electron microscopy images show that Cu2O/Pd network is composed of small and irregular fused nanoparticles with an average size of about 10 nm. Electrochemical results depict that the as-synthesized catalyst exhibits 2-fold higher activity for methanol oxidation than the commercially available 20% Pd/C catalyst and Pd black catalyst. Furthermore, CO-tolerance is also remarkably enhanced due to the presence of Cu2O. Such highly active, low-cost, and superiorly CO-tolerant catalysts of Cu2O/Pd Networks will open up a new avenue for direct methanol fuel cells.

  6. CXCR4-targeted and MMP-responsive iron oxide nanoparticles for enhanced magnetic resonance imaging.

    PubMed

    Gallo, Juan; Kamaly, Nazila; Lavdas, Ioannis; Stevens, Elizabeth; Nguyen, Quang-De; Wylezinska-Arridge, Marzena; Aboagye, Eric O; Long, Nicholas J

    2014-09-01

    MRI offers high spatial resolution with excellent tissue penetration but it has limited sensitivity and the commonly administered contrast agents lack specificity. In this study, two sets of iron oxide nanoparticles (IONPs) were synthesized that were designed to selectively undergo copper-free click conjugation upon sensing of matrix metalloproteinase (MMP) enzymes, thereby leading to a self-assembled superparamagnetic nanocluster network with T2 signal enhancement properties. For this purpose, IONPs with bioorthogonal azide and alkyne surfaces masked by polyethylene glycol (PEG) layers tethered to CXCR4-targeted peptide ligands were synthesized and characterized. The IONPs were tested in vitro and T2 signal enhancements of around 160 % were measured when the IONPs were incubated with cells expressing MMP2/9 and CXCR4. Simultaneous systemic administration of the bioorthogonal IONPs in tumor-bearing mice demonstrated the signal-enhancing ability of these 'smart' self-assembling nanomaterials.

  7. Gold nanoparticle-decorated graphene oxides for plasmonic-enhanced polymer photovoltaic devices.

    PubMed

    Chuang, Ming-Kai; Lin, Shih-Wei; Chen, Fang-Chung; Chu, Chih-Wei; Hsu, Chain-Shu

    2014-01-01

    In this work, gold nanoparticle/graphene oxide (AuNP/GO) nanocomposites are synthesized and used as anodic buffer layers in organic photovoltaic devices (OPVs). The application of thiol-terminated polyethylene glycol as a capping agent prevents the aggregation of AuNPs on the GO surface and further improves the solubility and stability of these nanomaterials in solutions. When AuNP/GO nanomaterials served as the buffer layers, they introduced localized surface plasmon resonance (LSPR) in the OPVs, leading to noticeable enhancements in the photocurrent and the efficiencies of the OPVs. We attribute the primary origin of the improvement in device performance to local field enhancement induced by the LSPR. We anticipate that this study might open up new avenues for constructing plasmon-enhancing layers on the nanoscale to improve the performance of solar cells.

  8. O-(carboxymethyl)-chitosan nanofiltration membrane surface functionalized with graphene oxide nanosheets for enhanced desalting properties.

    PubMed

    Wang, Jiali; Gao, Xueli; Wang, Jian; Wei, Yi; Li, Zhaokui; Gao, Congjie

    2015-02-25

    A novel O-(carboxymethyl)-chitosan (OCMC) nanofiltration (NF) membrane is developed via surface functionalization with graphene oxide (GO) nanosheets to enhance desalting properties. Using ring-opening polymerization between epoxy groups of GO nanosheets and amino groups of OCMC active layer, GO nanosheets are irreversibly bound to the membrane. The OCMC NF membranes surface-functionalized with GO nanosheets are characterized by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, contact angle analyzer, and zeta potential analyzer. The membranes exhibit not only higher permeability but also better salt rejections than the pristine membranes and the commercial NF membranes; besides, the desalting properties are enhanced with the concentration of GO nanosheets increasing. Furthermore, the transport mechanism of GO-OCMC NF membranes reveals that the nanoporous structure of GO-OCMC functional layer and size exclusion and electrostatic repulsion of water nanochannels formed by GO nanosheets lead to the membranes possessing enhanced desalting properties.

  9. Novel application of vacuum sealing drainage with continuous irrigation of potassium permanganate for managing infective wounds of gas gangrene.

    PubMed

    Hu, Ning; Wu, Xing-Huo; Liu, Rong; Yang, Shu-Hua; Huang, Wei; Jiang, Dian-Ming; Wu, Qiang; Xia, Tian; Shao, Zeng-Wu; Ye, Zhe-Wei

    2015-08-01

    Traumatic gas gangrene is a fatal infection mainly caused by Clostridium perfringens. It is a challenge to manage gas gangrene in open wounds and control infection after debridement or amputation. The aim of the present study was to use vacuum sealing drainage (VSD) with continuous irrigation of potassium permanganate to manage infective wounds of gas gangrene and observe its clinical efficacy. A total of 48 patients with open traumatic gas gangrene infection were included in this study. Amputations were done for 27 patients, and limb salvage procedures were performed for the others. After amputation or aggressive debridement, the VSD system, including polyvinyl alcohol (PVA) foam dressing and polyurethane (PU) film, with continuous irrigation of 1:5000 potassium permanganate solutions, was applied to the wounds. During the follow-up, all the patients healed without recurrence within 8-18 months. There were four complications. Cardiac arrest during amputation surgery occurred in one patient who suffered from severe septic shock. Emergent resuscitation was performed and the patient returned to stable condition. One patient suffered from mixed infection of Staphylococcal aureus, and a second-stage debridement was performed. One patient suffered from severe pain of the limb after the debridement. Exploratory operation was done and the possible reason was trauma of a local peripheral nerve. Three cases of crush syndrome had dialysis treatment for concomitant renal failure. In conclusion, VSD can convert open wound to closed wound, and evacuate necrotic tissues. Furthermore, potassium permanganate solutions help eliminate anaerobic microenvironment and achieve good therapeutic effect on gas gangrene and mixed infection. VSD with continuous irrigation of potassium permanganate is a novel, simple and feasible alternative for severe traumatic open wounds with gas gangrene infection.

  10. Gold nanoparticle-decorated graphene oxides for plasmonic-enhanced polymer photovoltaic devices

    NASA Astrophysics Data System (ADS)

    Chuang, Ming-Kai; Lin, Shih-Wei; Chen, Fang-Chung; Chu, Chih-Wei; Hsu, Chain-Shu

    2014-01-01

    In this work, gold nanoparticle/graphene oxide (AuNP/GO) nanocomposites are synthesized and used as anodic buffer layers in organic photovoltaic devices (OPVs). The application of thiol-terminated polyethylene glycol as a capping agent prevents the aggregation of AuNPs on the GO surface and further improves the solubility and stability of these nanomaterials in solutions. When AuNP/GO nanomaterials served as the buffer layers, they introduced localized surface plasmon resonance (LSPR) in the OPVs, leading to noticeable enhancements in the photocurrent and the efficiencies of the OPVs. We attribute the primary origin of the improvement in device performance to local field enhancement induced by the LSPR. We anticipate that this study might open up new avenues for constructing plasmon-enhancing layers on the nanoscale to improve the performance of solar cells.In this work, gold nanoparticle/graphene oxide (AuNP/GO) nanocomposites are synthesized and used as anodic buffer layers in organic photovoltaic devices (OPVs). The application of thiol-terminated polyethylene glycol as a capping agent prevents the aggregation of AuNPs on the GO surface and further improves the solubility and stability of these nanomaterials in solutions. When AuNP/GO nanomaterials served as the buffer layers, they introduced localized surface plasmon resonance (LSPR) in the OPVs, leading to noticeable enhancements in the photocurrent and the efficiencies of the OPVs. We attribute the primary origin of the improvement in device performance to local field enhancement induced by the LSPR. We anticipate that this study might open up new avenues for constructing plasmon-enhancing layers on the nanoscale to improve the performance of solar cells. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr05077g

  11. Effect of radiation energy and intracellular iron dose on iron oxide nanoparticle enhancement of radiation cytotoxicity

    NASA Astrophysics Data System (ADS)

    Mazur, Courtney M.; Strawbridge, Rendall R.; Thompson, Ella S.; Petryk, Alicia A.; Gladstone, David J.; Hoopes, P. Jack

    2015-03-01

    Iron oxide nanoparticles (IONPs) are one of several high-Z materials currently being investigated for their ability to enhance the cytotoxic effects of therapeutic ionizing radiation. Studies with iron oxide, silver, gold, and hafnium oxide suggest radiation dose, radiation energy, cell type, and the type and level of metallic nanoparticle are all critical factors in achieving radiation enhancement in tumor cells. Using a single 4 Gy radiation dose, we compared the level of tumor cell cytotoxicity at two different intracellular iron concentrations and two different radiation energies in vitro. IONPs were added to cell culture media at concentrations of 0.25 mg Fe/mL and 1.0 mg Fe/mL and incubated with murine breast adenocarcinoma (MTG-B) cells for 72 hours. Extracellular iron was then removed and cells were irradiated at either 662 keV or 10 MV. At the 0.25 mg Fe/mL dose (4 pg Fe/cell), radiation energy did not affect the level of cytotoxicity. However with 1.0 mg Fe/mL (9 pg Fe/cell), the higher 10 MV radiation energy resulted in 50% greater cytotoxicity as compared to cells without IONPs irradiated at this energy. These results suggest IONPs may be able to significantly enhance the cytotoxic effects of radiation and improve therapeutic ratio if they can be selectively associated with cancer cells and/or tumors. Ongoing in vivo studies of IONP radiation enhancement in a murine tumor model are too immature to draw conclusions from at this time, however preliminary data suggests similar effectiveness of IONP radiation enhancement at 6 MV and 18 MV energy levels. In addition to the IONP-based radiation enhancement demonstrated here, the use of tumor-localized IONP with an externally delivered, non-toxic alternating magnetic field affords the opportunity to selectively heat and kill tumor cells. Combining IONP-based radiation sensitization and heat-based cytotoxicity provides a unique and potentially highly effective opportunity for therapeutic ratio enhancement.

  12. Electrochemical enhancement of nitric oxide removal from simulated lean-burn engine exhaust via solid oxide fuel cells.

    PubMed

    Huang, Ta-Jen; Wu, Chung-Ying; Lin, Yu-Hsien

    2011-07-01

    A solid oxide fuel cell (SOFC) unit is constructed with Ni-YSZ as the anode, YSZ as the electrolyte, and La(0.6)Sr(0.4)CoO(3)-Ce(0.9)Gd(0.1)O(1.95) as the cathode. The SOFC operation is performed at 600 °C with a cathode gas simulating the lean-burn engine exhaust and at various fixed voltage, at open-circuit voltage, and with an inert gas flowing over the anode side, respectively. Electrochemical enhancement of NO decomposition occurs when an operating voltage is generated; higher O(2) concentration leads to higher enhancement. Smaller NO concentration results in larger NO conversion. Higher operating voltage and higher O(2) concentration can lead to both higher NO conversion and lower fuel consumption. The molar rate of the consumption of the anode fuel can be very much smaller than that of NO to N(2) conversion. This makes the anode fuel consumed in the SOFC-DeNO(x) process to be much less than the equivalent amount of ammonia consumed in the urea-based selective catalytic reduction process. Additionally, the NO conversion increases with the addition of propylene and SO(2) into the cathode gas. These are beneficial for the application of the SOFC-DeNO(x) technology on treating diesel and other lean-burn engine exhausts.

  13. Complex I inhibition augments dichloroacetate cytotoxicity through enhancing oxidative stress in VM-M3 glioblastoma cells

    PubMed Central

    Poff, Angela M.; Koutnik, Andrew P.; D’Agostino, Dominic P.

    2017-01-01

    The robust glycolytic metabolism of glioblastoma multiforme (GBM) has proven them susceptible to increases in oxidative metabolism induced by the pyruvate mimetic dichloroacetate (DCA). Recent reports demonstrate that the anti-diabetic drug metformin enhances the damaging oxidative stress associated with DCA treatment in cancer cells. We sought to elucidate the role of metformin’s reported activity as a mitochondrial complex I inhibitor in the enhancement of DCA cytotoxicity in VM-M3 GBM cells. Metformin potentiated DCA-induced superoxide production, which was required for enhanced cytotoxicity towards VM-M3 cells observed with the combination. Similarly, rotenone enhanced oxidative stress resultant from DCA treatment and this too was required for the noted augmentation of cytotoxicity. Adenosine monophosphate kinase (AMPK) activation was not observed with the concentration of metformin required to enhance DCA activity. Moreover, addition of an activator of AMPK did not enhance DCA cytotoxicity, whereas an inhibitor of AMPK heightened the cytotoxicity of the combination. Our data indicate that metformin enhancement of DCA cytotoxicity is dependent on complex I inhibition. Particularly, that complex I inhibition cooperates with DCA-induction of glucose oxidation to enhance cytotoxic oxidative stress in VM-M3 GBM cells. PMID:28644886

  14. Understanding and Enhancing the Photostability of Nanoporous Metal Oxide Thin Films for Solar Hydrogen Generation

    NASA Astrophysics Data System (ADS)

    Chitrada, Kalyan Chakravarthi

    Solar water splitting is an environmentally benign process which has received wide attention in the recent years as an alternate method for a clean and safe production of hydrogen. This process employs a semiconductor based photocatalyst, water, and sunlight to produce hydrogen. Metal-oxide based semiconductors are considered to be ideal photocatalytic materials because of their stability against photo-corrosion combined with relatively narrow energy band-gap, appropriately placed band edge positions with reference to oxygen and hydrogen energy levels, less scattering of charges due to wider valence band, high dielectric constant, natural abundance, and non-toxicity. In this dissertation, two metal oxide based semiconductors viz., iron (III) oxide and bismuth (III) oxide were investigated to understand and enhance their photo activity as photoanodes for solar water splitting application. Iron (III) oxide has a well suited band gap to capture solar spectrum but it suffers from inappropriately positioned band edges, recombination losses due to low electron mobility, and a small minority carrier diffusion length. However, it was hypothesized that the Iron (III) oxide might show interesting photoelectrochemical properties by alloying with 4f elements and shifting the conduction band minimum of the iron oxide favorably to more negative potentials. In the present study, a nanoporous iron oxide layer incorporated with Nd3+ and B3+ was synthesized by electrochemical anodization of a FeNdB alloy. The photoelectrochemical behavior of this oxide was compared with thermally oxidized FeNdB alloy and the iron oxides obtained by anodization and thermal oxidation of pure iron foil. Incorporation of Nd3+ and B3+ in the iron oxide showed a direct bandgap of 2.05 eV, an indirect bandgap of 1.9 eV and shifted the flatband potentials to --0.8 VAg/AgCl in 1 M KOH solution. The FeNdB oxide showed marginally better catalytic activity for the oxygen evolution reaction than pure iron oxide

  15. Fully Converting Graphite into Graphene Oxide Hydrogels by Preoxidation with Impure Manganese Dioxide.

    PubMed

    Sun, Jiaojiao; Yang, Ningxin; Sun, Zhe; Zeng, Mengqi; Fu, Lei; Hu, Chengguo; Hu, Shengshui

    2015-09-30

    Potassium permanganate (KMnO4) has been proved to be an efficient oxidant for converting graphite into graphite oxide, but its slow diffusion in the interlayer of graphite seriously restricts the production of graphene oxide (GO). Here, we demonstrate that the preoxidation of graphite by impure manganese dioxide (MnO2) in a mixture of concentrated sulfuric acid (H2SO4) and phosphorus pentoxide (P2O5) can efficiently improve the synthesis of GO when KMnO4 is employed as the oxidant. The prepared honey-like GO hydrogels possess a high yield of single-layer sheets, large sizes (average lateral size up to 20 μm), wide ranges of stable dispersion concentrations (from dilute solutions, viscous hydrogels, to dry films), and good conductivity after reduction (~2.9 × 10(4) S/m). The mechanism for the improved synthesis of GO by impure MnO2 was explored. The enhanced exfoliation and oxidation of graphite by oxidative Mn ions (mainly Mn(3+)), which are synergistically produced by the reaction of impure MnO2 with H2SO4 and P2O5, are found to be responsible for the improved synthesis of such GO hydrogels. Particularly, preoxidized graphite (POG) can be partially dispersed in water with sonication, which allows the facile construction of flexible and highly conductive graphene nanosheet film electrodes with excellent electrochemical sensing properties.

  16. Reduced graphene oxide/CeO{sub 2} nanocomposite with enhanced photocatalytic performance

    SciTech Connect

    Kaur, Jasmeet Anand, Kanika; Singh, Gurpreet; Hastir, Anita; Virpal,; Singh, Ravi Chand; Anand, Kanica

    2015-05-15

    In this work, reduced graphene oxide /cerium oxide (RGO/CeO{sub 2}) nanocomposite was synthesized by in situ reduction of cerium nitrate Ce(NO{sub 3}){sub 3}·6H{sub 2}O in the presence of graphene oxide by hydrazine hydrate (N{sub 2}H{sub 4}.H{sub 2}O). The intrinsic characteristics of as-prepared nanocomposite were studied using powder x-ray diffraction (XRD), Raman spectroscopy and field-emission scanning electron microscopy (FESEM). The photocatalytic degradation of methylene blue (MB) was employed as a model reaction to evaluate the photocatalytic activity of the RGO/CeO{sub 2} nanocomposite. The as-obtained RGO/CeO{sub 2} nanocomposite displays a significantly enhanced photocatalytic degradation of MB dye in comparison with bare CeO{sub 2} nanoparticles under sunlight irradiation, which can be attributed to the improved separation of electron-hole pairs and enhanced adsorption performance due to presence of RGO.

  17. Proton-insertion-enhanced pseudocapacitance based on the assembly structure of tungsten oxide.

    PubMed

    Zhu, Minshen; Meng, Wenjun; Huang, Yan; Huang, Yang; Zhi, Chunyi

    2014-11-12

    The capacitances of supercapacitors with carbon and metal oxides as electrodes are usually associated with the available surface areas of the electrode materials. However, in this paper, we report that proton insertion, an unusual capacitive mechanism, may effectively enhance the capacitance of metal oxides with low surface area but specific structures. Tungsten trioxide (WO3) as the electrode material for supercapacitors has always suffered from low capacitance. Nevertheless, enhanced by the proton insertion mechanism, we demonstrate that electrodes fabricated by an assembly structure of hexagonal-phase WO3 (h-WO3) nanopillars achieve a high capacitance of up to 421.8 F g(-1) under the current density of 0.5 A g(-1), which is the highest capacitance achieved with pure WO3 as the electrodes so far, to the best of our knowledge. Detailed analyses indicate that proton insertion dominates the electrochemical behavior of h-WO3 and plays the key role in reaching high capacitance by excluding other mechanisms. In addition, a thorough investigation on the temperature-dependent electrochemical performance reveals excellent performance stability at different temperatures. This study provides a new approach to achieving high capacitance by effective proton insertion into ordered tunnels in crystallized metal oxides, which is primarily important for the fabrication of compact high-performance energy storage devices.

  18. Pioglitazone Enhances Cytosolic Lipolysis, β-oxidation and Autophagy to Ameliorate Hepatic Steatosis.

    PubMed

    Hsiao, Pi-Jung; Chiou, Hsin-Ying Clair; Jiang, He-Jiun; Lee, Mei-Yueh; Hsieh, Tusty-Jiuan; Kuo, Kung-Kai

    2017-08-22

    Non-alcoholic fatty liver disease closely contributes to the development of obesity and insulin resistance. Even though pioglitazone has been reported to effectively lessen hepatic steatosis in human studies, its molecular mechanism remains unclear. This study is designed to investigate the regulation of cytosolic lipolysis, β-oxidation and autophagy by pioglitazone in a mice model of high fat diet (HFD) and cell model incubated with palmitic acid. Our results revealed hepatic steatosis was apparently induced by HFD and it was significantly reversed by pioglitazone. The serum insulin and hepatic triglyceride content was significantly decreased by co-administered pioglitazone with HFD. Hepatic expression of cytosolic-lipolysis related proteins (ATGL, HSL), β-oxidation (CPT-1A) and autophagy-related proteins (ATG7, LC3, LAL) was significantly enhanced by pioglitazone. Knockdown PPARα/PPARγ in AML12 cells significantly and proportionally reduced the expressions of ATGL, CPT-1A and LC3II, which was induced by pioglitazone. Furthermore, facilitation of the autophagic flux by pioglitazone was obviously blocked by lysosomal inhibitor, leupeptin, to demonstrate accumulation of the LC3II and intracellular lipid in AML12 cells. Our results demonstrated that pioglitazone attenuating the hepatic steatosis may be mediated by enhancing cytosolic lipolysis, β-oxidation and autophagy in a PPARα and PPARγ dependent manner.

  19. Enhancement of oxidative and drought tolerance in Arabidopsis by overaccumulation of antioxidant flavonoids

    PubMed Central

    Nakabayashi, Ryo; Yonekura-Sakakibara, Keiko; Urano, Kaoru; Suzuki, Makoto; Yamada, Yutaka; Nishizawa, Tomoko; Matsuda, Fumio; Kojima, Mikiko; Sakakibara, Hitoshi; Shinozaki, Kazuo; Michael, Anthony J; Tohge, Takayuki; Yamazaki, Mami; Saito, Kazuki

    2014-01-01

    The notion that plants use specialized metabolism to protect against environmental stresses needs to be experimentally proven by addressing the question of whether stress tolerance by specialized metabolism is directly due to metabolites such as flavonoids. We report that flavonoids with radical scavenging activity mitigate against oxidative and drought stress in Arabidopsis thaliana. Metabolome and transcriptome profiling and experiments with oxidative and drought stress in wild-type, single overexpressors of MYB12/PFG1 (PRODUCTION OF FLAVONOL GLYCOSIDES1) or MYB75/PAP1 (PRODUCTION OF ANTHOCYANIN PIGMENT1), double overexpressors of MYB12 and PAP1, transparent testa4 (tt4) as a flavonoid-deficient mutant, and flavonoid-deficient MYB12 or PAP1 overexpressing lines (obtained by crossing tt4 and the individual MYB overexpressor) demonstrated that flavonoid overaccumulation was key to enhanced tolerance to such stresses. Antioxidative activity assays using 2,2-diphenyl-1-picrylhydrazyl, methyl viologen, and 3,3′-diaminobenzidine clearly showed that anthocyanin overaccumulation with strong in vitro antioxidative activity mitigated the accumulation of reactive oxygen species in vivo under oxidative and drought stress. These data confirm the usefulness of flavonoids for enhancing both biotic and abiotic stress tolerance in crops. PMID:24274116

  20. Enhanced OXPHOS, glutaminolysis and β-oxidation constitute the metastatic phenotype of melanoma cells.

    PubMed

    Rodrigues, Mariana F; Obre, Emilie; de Melo, Fabiana H M; Santos, Gilson C; Galina, Antonio; Jasiulionis, Miriam G; Rossignol, Rodrigue; Rumjanek, Franklin D; Amoêdo, Nivea D

    2016-03-15

    Tumours display different cell populations with distinct metabolic phenotypes. Thus, subpopulations can adjust to different environments, particularly with regard to oxygen and nutrient availability. Our results indicate that progression to metastasis requires mitochondrial function. Our research, centered on cell lines that display increasing degrees of malignancy, focused on metabolic events, especially those involving mitochondria, which could reveal which stages are mechanistically associated with metastasis. Melanocytes were subjected to several cycles of adhesion impairment, producing stable cell lines exhibiting phenotypes representing a progression from non-tumorigenic to metastatic cells. Metastatic cells (4C11+) released the highest amounts of lactate, part of which was derived from glutamine catabolism. The 4C11+ cells also displayed an increased oxidative metabolism, accompanied by enhanced rates of oxygen consumption coupled to ATP synthesis. Enhanced mitochondrial function could not be explained by an increase in mitochondrial content or mitochondrial biogenesis. Furthermore, 4C11+ cells had a higher ATP content, and increased succinate oxidation (complex II activity) and fatty acid oxidation. In addition, 4C11+ cells exhibited a 2-fold increase in mitochondrial membrane potential (ΔΨmit). Consistently, functional assays showed that the migration of cells depended on glutaminase activity. Metabolomic analysis revealed that 4C11+ cells could be grouped as a subpopulation with a profile that was quite distinct from the other cells investigated in the present study. The results presented here have centred on how the multiple metabolic inputs of tumour cells may converge to compose the so-called metastatic phenotype.

  1. Enhanced dewaterability of sewage sludge with zero-valent iron-activated persulfate oxidation system.

    PubMed

    Hu, Lingling; Liao, Yu; He, Chun; Pan, Wenqi; Liu, Shangkun; Yang, Yichang; Li, Shuzhen; Sun, Lianpeng

    2015-01-01

    The potential benefits of zero-valent iron-activated persulfate (Na2S2O8) oxidation in enhanced dewaterability of sludge, along with the associated mechanisms were investigated in this study. The sludge dewaterability was evaluated in terms of specific resistance to filtration (SRF) and water content. Based on these indexes, it was observed that ZVI-S2O8(2) oxidation effectively improved sludge dewaterability. The optimal conditions to give preferable dewaterability were found when the molar ratio of ZVI/S2O8(2-) was 5:1 and pH value was 3.0. The most important mechanism was proposed to be the degradation of extracellular polymeric substances (EPS) incorporated in sludge flocs and rupture of microbial cells. Three-dimensional excitation-emission matrix fluorescence spectra revealed that the powerful SO4- and ·OH generated from ZVI-S2O8(2-) system destroyed the particular functional groups of fluorescing substances (aromatic protein-like and tryptophan protein-like substances), resulting in the release of bound water and the subsequent enhancement of dewaterability. Therefore, ZVI/S2O8(2-) oxidation is an alternative approach showing great potential to be applied in sludge treatment plants.

  2. Using graphene oxide to enhance the activity of anammox bacteria for nitrogen removal.

    PubMed

    Wang, Dong; Wang, Guowen; Zhang, Guoquan; Xu, Xiaochen; Yang, Fenglin

    2013-03-01

    Graphene oxide (GO) was applied in this study to enhance the activity of anaerobic ammonium oxidation (anammox) bacteria for nitrogen removal. A GO dose-dependent effect on anammox bacteria was observed through batch tests. The results showed that the activity increased as the GO dose was varied within 0.05-0.1gL(-1). A maximum 10.26% increase of anaerobic ammonium oxidizing activity was achieved at 0.1gL(-1) GO. Analysis of extracellular polymeric substances (EPS) indicated that the highest carbohydrate, protein, and total EPS contents (42.5, 125.7, and 168.2mg (g volatile suspended solids)(-1), respectively) were obtained with 0.1gL(-1) GO. Appropriate GO dose stimulated EPS production to promote the activity of anammox bacteria. Transmission electron microscopy showed the large surface area of GO benefited cell attachment. These findings proved that the application of GO was an effective approach to enhancing the activity of anammox bacteria. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Enhanced dispersion and the reactivity of atomically thin Rh layers supported by molybdenum oxide films

    NASA Astrophysics Data System (ADS)

    Szenti, Imre; Bugyi, László; Kónya, Zoltán

    2015-11-01

    The behavior of rhodium layers deposited on oxidized, 0.15-20.0 ML thick Mo films formed on a nearly stoichiometric TiO2(110) single crystal was characterized by AES, TPD and work function (WF) measurements. The oxidation of 0.15-2.7 ML thick Mo deposits was performed via the redox reaction with the titania support at 1000 K. Molybdenum oxide supports of MoO3 and MoO2 surface composition were formed by the oxidation of 20 ML thick Mo multilayers by O2 at 650 K and 1000 K, respectively. Rh grows in a layer-by-layer fashion on a mixed titanium-molybdenum oxide produced in the reaction between titania and 0.15 ML Mo, corresponding to a considerably enhanced dispersion of rhodium as compared with that on the clean TiO2(110). The surface reactivity of Rh layers supported by molybdenum oxides as a function of pre-annealing temperature was followed by carbon monoxide adsorption-desorption cycles. The CO uptake of a 0.4 ML thick Rh film formed on the MoO3 support was strongly suppressed at 300 K, indicating the encapsulation of rhodium with MoOX species of low surface free energy. The CO adsorption capability of rhodium particles supported by both MoO3 and MoO2 layers was eliminated due to pre-annealing at 600 K, related to the extended decoration of metal particles by MoOX moiety. The encapsulation of the rhodium films proceeded above 600 K on both supports, and annealing to 1000 K resulted in nearly equal WF values, indicating the formation of MoOX overlayers of similar surface composition close to MoO2. AES depth profiles revealed that the 0.4 ML thick Rh deposits covered by MoOX at 1000 K preserved their island structure.

  4. Enhancement of atmospheric H2SO4 / H2O nucleation: organic oxidation products versus amines

    NASA Astrophysics Data System (ADS)

    Berndt, T.; Sipilä, M.; Stratmann, F.; Petäjä, T.; Vanhanen, J.; Mikkilä, J.; Patokoski, J.; Taipale, R.; Mauldin, R. L., III; Kulmala, M.

    2014-01-01

    Atmospheric H2SO4 / H2O nucleation influencing effects have been studied in the flow tube IfT-LFT (Institute for Tropospheric Research - Laminar Flow Tube) at 293 ± 0.5 K and a pressure of 1 bar using synthetic air as the carrier gas. The presence of a possible background amine concentration in the order of 107-108 molecule cm-3 throughout the experiments has to be taken into account. In a first set of investigations, ozonolysis of olefins (tetramethylethylene, 1-methyl-cyclohexene, α-pinene and limonene) for close to atmospheric concentrations, served as the source of OH radicals and possibly other oxidants initiating H2SO4 formation starting from SO2. The oxidant generation is inevitably associated with the formation of organic oxidation products arising from the parent olefins. These products (first generation mainly) showed no clear effect on the number of nucleated particles within a wide range of experimental conditions for H2SO4 concentrations higher than ~107 molecule cm-3. Also the early growth process of the nucleated particles was not significantly influenced by the organic oxidation products in line with the expected growth by organic products using literature data. An additional, H2SO4-independent process of particle (nano-CN) formation was observed in the case of α-pinene and limonene ozonolysis for H2SO4 concentrations smaller than ~107 molecule cm-3. Furthermore, the findings confirm the appearance of an additional oxidant for SO2 beside OH radicals, very likely stabilized Criegee Intermediates (sCI). A second set of experiments has been performed in the presence of added amines in the concentrations range of a few 107-1010 molecule cm-3 applying photolytic OH radical generation for H2SO4 production without addition of other organics. All amines showed significant nucleation enhancement with increasing efficiency in the order pyridine < aniline < dimethylamine < trimethylamine. This result supports the idea of H2SO4 cluster stabilization by

  5. Mangiferin protects against adverse skeletal muscle changes and enhances muscle oxidative capacity in obese rats

    PubMed Central

    Acevedo, Luz M.; Raya, Ana I.; Martínez-Moreno, Julio M.

    2017-01-01

    Obesity-related skeletal muscle changes include muscle atrophy, slow-to-fast fiber-type transformation, and impaired mitochondrial oxidative capacity. These changes relate with increased risk of insulin resistance. Mangiferin, the major component of the plant Mangifera indica, is a well-known anti-inflammatory, anti-diabetic, and antihyperlipidemic agent. This study tested the hypothesis that mangiferin treatment counteracts obesity-induced fiber atrophy and slow-to-fast fiber transition, and favors an oxidative phenotype in skeletal muscle of obese rats. Obese Zucker rats were fed gelatin pellets with (15 mg/kg BW/day) or without (placebo group) mangiferin for 8 weeks. Lean Zucker rats received the same gelatin pellets without mangiferin and served as non-obese and non-diabetic controls. Lesser diameter, fiber composition, and histochemical succinic dehydrogenase activity (an oxidative marker) of myosin-based fiber-types were assessed in soleus and tibialis cranialis muscles. A multivariate discriminant analysis encompassing all fiber-type features indicated that obese rats treated with mangiferin displayed skeletal muscle phenotypes significantly different compared with both lean and obese control rats. Mangiferin significantly decreased inflammatory cytokines, preserved skeletal muscle mass, fiber cross-sectional size, and fiber-type composition, and enhanced muscle fiber oxidative capacity. These data demonstrate that mangiferin attenuated adverse skeletal muscle changes in obese rats. PMID:28253314

  6. Sensing the dynamics of oxidative stress using enhanced absorption in protein-loaded random media.

    PubMed

    Suárez, Guillaume; Santschi, Christian; Slaveykova, Vera I; Martin, Olivier J F

    2013-12-09

    Reactive oxygen species play a key role in cell signalling and oxidative stress mechanisms, therefore, sensing their production by living organisms is of fundamental interest. Here we describe a novel biosensing method for extracellular detection of endogenous hydrogen peroxide (H2O2). The method is based on the enhancement of the optical absorption spectrum of the hemoprotein cytochrome c when loaded into a highly scattering random medium. Such a configuration enables, in contrast to existing techniques, non-invasive and dynamic detection of the oxidation of cyt c in the presence of H2O2 with unprecedented sensitivity. Dynamic information on the modification of the cell oxidative status of Chlamydomonas reinhardtii, an aquatic green algae, was obtained under oxidative stress conditions induced by the presence of trace concentrations of Cd(II). Furthermore, the dynamics of H2O2 production was investigated under different lighting conditions confirming the impact of Cd(II) on the photosynthetic activity of those phytoplanktonic cells.

  7. Sensing the dynamics of oxidative stress using enhanced absorption in protein-loaded random media

    PubMed Central

    Suárez, Guillaume; Santschi, Christian; Slaveykova, Vera I.; Martin, Olivier J. F.

    2013-01-01

    Reactive oxygen species play a key role in cell signalling and oxidative stress mechanisms, therefore, sensing their production by living organisms is of fundamental interest. Here we describe a novel biosensing method for extracellular detection of endogenous hydrogen peroxide (H2O2). The method is based on the enhancement of the optical absorption spectrum of the hemoprotein cytochrome c when loaded into a highly scattering random medium. Such a configuration enables, in contrast to existing techniques, non-invasive and dynamic detection of the oxidation of cyt c in the presence of H2O2 with unprecedented sensitivity. Dynamic information on the modification of the cell oxidative status of Chlamydomonas reinhardtii, an aquatic green algae, was obtained under oxidative stress conditions induced by the presence of trace concentrations of Cd(II). Furthermore, the dynamics of H2O2 production was investigated under different lighting conditions confirming the impact of Cd(II) on the photosynthetic activity of those phytoplanktonic cells. PMID:24316586

  8. The enhanced oxidation of SO2 by NO2 on carbon particulates

    NASA Technical Reports Server (NTRS)

    Cofer, W. R., III; Schryer, D. R.; Rogowski, R. S.

    1980-01-01

    The oxidation of SO2 on carbon particles in dry air and in air at 65% relative humidity (RH) was found to be greatly enhanced by the presence of gaseous NO2. Exposures of 20-80ppm SO2 + 10ppm NO2 on 1-mg samples of commercial carbon black were found to produce both sorption and desorption coverages (weight retained after desorption into N2) of over one order of magnitude greater than for corresponding SO2 exposures. Significant agglomeration and wetting were observed to occur progressively during exposures at 65% RH, and samples, even after 150-h exposure, rarely reached steady-state weight gain. The wetting may have regenerated fresh reactive carbon surface. Sorptions conducted in nitrogen atmospheres, rather than in air, appeared to produce slightly higher sorptions and weight retentions for equivalent exposure concentrations and times, indicating that NO2 served as the oxidizer and that molecular oxygen, or some trace constitutents in air, may have weakly inhibited the oxidation by NO2. Wet chemical analysis of the desorbed phase indicated that sulfate, presumably H2SO4 accounted for over half of the retained weight. Measurements of pH from water-quenched samples indicated a highly acidic surface phase, and suggested the oxidation process could proceed in an acidic environment.

  9. Mangiferin protects against adverse skeletal muscle changes and enhances muscle oxidative capacity in obese rats.

    PubMed

    Acevedo, Luz M; Raya, Ana I; Martínez-Moreno, Julio M; Aguilera-Tejero, Escolástico; Rivero, José-Luis L

    2017-01-01

    Obesity-related skeletal muscle changes include muscle atrophy, slow-to-fast fiber-type transformation, and impaired mitochondrial oxidative capacity. These changes relate with increased risk of insulin resistance. Mangiferin, the major component of the plant Mangifera indica, is a well-known anti-inflammatory, anti-diabetic, and antihyperlipidemic agent. This study tested the hypothesis that mangiferin treatment counteracts obesity-induced fiber atrophy and slow-to-fast fiber transition, and favors an oxidative phenotype in skeletal muscle of obese rats. Obese Zucker rats were fed gelatin pellets with (15 mg/kg BW/day) or without (placebo group) mangiferin for 8 weeks. Lean Zucker rats received the same gelatin pellets without mangiferin and served as non-obese and non-diabetic controls. Lesser diameter, fiber composition, and histochemical succinic dehydrogenase activity (an oxidative marker) of myosin-based fiber-types were assessed in soleus and tibialis cranialis muscles. A multivariate discriminant analysis encompassing all fiber-type features indicated that obese rats treated with mangiferin displayed skeletal muscle phenotypes significantly different compared with both lean and obese control rats. Mangiferin significantly decreased inflammatory cytokines, preserved skeletal muscle mass, fiber cross-sectional size, and fiber-type composition, and enhanced muscle fiber oxidative capacity. These data demonstrate that mangiferin attenuated adverse skeletal muscle changes in obese rats.

  10. Chemical and magnetic functionalization of graphene oxide as a route to enhance its biocompatibility

    NASA Astrophysics Data System (ADS)

    Urbas, Karolina; Aleksandrzak, Malgorzata; Jedrzejczak, Magdalena; Jedrzejczak, Malgorzata; Rakoczy, Rafal; Chen, Xuecheng; Mijowska, Ewa

    2014-12-01

    The novel approach for deposition of iron oxide nanoparticles with narrow size distribution supported on different sized graphene oxide was reported. Two different samples with different size distributions of graphene oxide (0.5 to 7 μm and 1 to 3 μm) were selectively prepared, and the influence of the flake size distribution on the mitochondrial activity of L929 with WST1 assay in vitro study was also evaluated. Little reduction of mitochondrial activity of the GO-Fe3O4 samples with broader size distribution (0.5 to 7 μm) was observed. The pristine GO samples (0.5 to 7 μm) in the highest concentrations reduced the mitochondrial activity significantly. For GO-Fe3O4 samples with narrower size distribution, the best biocompatibility was noticed at concentration 12.5 μg/mL. The highest reduction of cell viability was noted at a dose 100 μg/mL for GO (1 to 3 μm). It is worth noting that the chemical functionalization of GO and Fe3O4 is a way to enhance the biocompatibility and makes the system independent of the size distribution of graphene oxide.

  11. Lipopolysaccharide enhances oxidative modification of low density lipoprotein by copper ions, endothelial and smooth muscle cells.

    PubMed

    Maziere, C; Conte, M A; Dantin, F; Maziere, J C

    1999-03-01

    The effect of lipopolysaccharide (LPS, endotoxin) on low density lipoprotein (LDL) oxidative modification by copper ions, endothelial and smooth muscle cells was studied by determination of the level of lipid peroxidation products (thiobarbituric acid reactive substances or TBARS), the diene level and the electrophoretic mobility of the LDL particle. LPS 25-75 microg/ml induced a dose-dependent increase in LDL oxidation by copper ions, endothelial and smooth muscle cells. At 75 microg LPS/ml, the TBARS content was 1.9, 1.6, and 1.8-fold increased, respectively. The LDL degradation by J774 macrophage-like cells was concomitantly stimulated. Preincubation of the LDL particle with LPS induced a marked increase in the subsequent LDL oxidative modification either by copper ions or by endothelial and smooth muscle cells. In addition, pretreatment of endothelial and smooth muscle cells with LPS also induced an enhancement of LDL oxidative modification performed in the absence of LPS. This effect was accompanied by a parallel increase in superoxide anion release by the cells. These results point at one of the mechanisms involved in the described association between bacterial infection and acute myocardial infarction as well as coronary heart disease.

  12. Hydrogen sulfide enhances nitric oxide-induced tolerance of hypoxia in maize (Zea mays L.).

    PubMed

    Peng, Renyi; Bian, Zhiyuan; Zhou, Lina; Cheng, Wei; Hai, Na; Yang, Changquan; Yang, Tao; Wang, Xinyu; Wang, Chongying

    2016-11-01

    Our data present H 2 S in a new role, serving as a multi-faceted transducer to different response mechanisms during NO-induced acquisition of tolerance to flooding-induced hypoxia in maize seedling roots. Nitric oxide (NO), serving as a secondary messenger, modulates physiological processes in plants. Recently, hydrogen sulfide (H2S) has been demonstrated to have similar signaling functions. This study focused on the effects of treatment with H2S on NO-induced hypoxia tolerance in maize seedlings. The results showed that treatment with the NO donor sodium nitroprusside (SNP) enhanced survival rate of submerged maize roots through induced accumulation of endogenous H2S. The induced H2S then enhanced endogenous Ca(2+) levels as well as the Ca(2+)-dependent activity of alcohol dehydrogenase (ADH), improving the capacity for antioxidant defense and, ultimately, the hypoxia tolerance in maize seedlings. In addition, NO induced the activities of key enzymes in H2S biosynthesis, such as L-cysteine desulfhydrases (L-CDs), O-acetyl-L-serine (thiol)lyase (OAS-TL), and β-Cyanoalanine Synthase (CAS). SNP-induced hypoxia tolerance was enhanced by the application of NaHS, but was eliminated by the H2S-synthesis inhibitor hydroxylamine (HA) and the H2S-scavenger hypotaurine (HT). H2S concurrently enhanced the transcriptional levels of relative hypoxia-induced genes. Together, our findings indicated that H2S serves as a multi-faceted transducer that enhances the nitric oxide-induced hypoxia tolerance in maize (Zea mays L.).

  13. Ligand-Enhanced Abiotic Iron Oxidation and the Effects of Chemical versus Biological Iron Cycling in Anoxic Environments

    PubMed Central

    2013-01-01

    This study introduces a newly isolated, genetically tractable bacterium (Pseudogulbenkiania sp. strain MAI-1) and explores the extent to which its nitrate-dependent iron-oxidation activity is directly biologically catalyzed. Specifically, we focused on the role of iron chelating ligands in promoting chemical oxidation of Fe(II) by nitrite under anoxic conditions. Strong organic ligands such as nitrilotriacetate and citrate can substantially enhance chemical oxidation of Fe(II) by nitrite at circumneutral pH. We show that strain MAI-1 exhibits unambiguous biological Fe(II) oxidation despite a significant contribution (∼30–35%) from ligand-enhanced chemical oxidation. Our work with the model denitrifying strain Paracoccus denitrificans further shows that ligand-enhanced chemical oxidation of Fe(II) by microbially produced nitrite can be an important general side effect of biological denitrification. Our assessment of reaction rates derived from literature reports of anaerobic Fe(II) oxidation, both chemical and biological, highlights the potential competition and likely co-occurrence of chemical Fe(II) oxidation (mediated by microbial production of nitrite) and truly biological Fe(II) oxidation. PMID:23402562

  14. Enhancement of macrophage survival and DNA synthesis by oxidized-low-density-lipoprotein (LDL)-derived lipids and by aggregates of lightly oxidized LDL.

    PubMed Central

    Hamilton, J A; Jessup, W; Brown, A J; Whitty, G

    2001-01-01

    Human atherosclerotic plaque contains a partially characterized range of normal and oxidized lipids formed mainly from free and esterified cholesterol and phospholipids, some of which can be located in macrophage-derived "foam" cells. Oxidation of low-density lipoprotein (LDL) is often considered as an important event leading to subsequent foam-cell development, which may also include enhanced cell survival and/or proliferation. The active component(s) in oxidized LDL (ox.LDL) causing macrophage proliferation is debated. We report here that the lipid component of ox.LDL can promote macrophage survival and DNA synthesis, the latter response showing a synergistic effect in the presence of low concentrations of macrophage colony-stimulating factor. 7-Ketocholesterol showed some stimulation of macrophage DNA synthesis whereas hypochlorite-oxidized (i.e. apolipoprotein B-oxidized) LDL did not. Plaque-derived lipids could enhance macrophage survival. It has not been proven that LDL in lesions is oxidized sufficiently to be the dominant source of sterols in vivo or to be able to induce macrophage growth in vitro or in vivo; it has been suggested that aggregation of modified LDL in vivo is an important step in the deposition of intracellular lipid. We found that aggregation of lightly oxidized LDL potentiated dramatically its ability to stimulate macrophage DNA synthesis, indicating that extensive oxidation of LDL is not required for this response in vitro and perhaps in vivo. PMID:11256965

  15. Enhanced monitoring of hazardous waste site remediation: Electrical conductivity tomography and citizen monitoring of remediation through the EPA's community advisory group program

    NASA Astrophysics Data System (ADS)

    Hort, Ryan D.

    In situ chemical oxidation using permanganate has become a common method for degrading trichloroethene (TCE) in contaminated aquifers. Its effectiveness, however, is dependent upon contact between the oxidant and contaminant. Monitoring permanganate movement after injection is often hampered by aquifer heterogeneity and insufficient well coverage. Time lapse electrical conductivity tomography increases the spatial extent of monitoring beyond well locations. This technique can create two- or three-dimensional images of the electrical conductivity within the aquifer to monitor aquifer chemistry changes caused by permanganate injection and oxidation reactions. In-phase and quadrature electrical conductivity were measured in homogeneous aqueous and porous media samples to determine the effects of TCE and humate oxidation by permanganate on both measures of conductivity. Further effects of clean sand, 10% kaolinite (v/v), and 10% smectite (v/v) on both types of conductivity were studied as well. Finally, in-phase electrical conductivity was measured over time after injecting permanganate solution into two-dimensional tanks containing artificial groundwater with and without TCE to observe the movement of the permanganate plume and its interaction with TCE and to examine the effectiveness of time-lapse conductivity tomography for monitoring the plume's movement. In-phase electrical conductivity after oxidation reactions involving permanganate, TCE, and humate could be accurately modeled in homogeneous batch samples. Use of forward modeling of in-phase conductivity from permanganate concentrations may be useful for improving recovery of conductivity values during survey inversion, but further work is needed combining the chemistry modeling with solute transport models. Small pH-related quadrature conductivity decreases were observed after TCE oxidation, and large quadrature conductivity increases were observed as a result of sodium ion addition; however, quadrature

  16. Metal oxide-based silver substrates for surface-enhanced Raman scattering

    SciTech Connect

    Li, Y.S.; Lin, X.

    1995-12-01

    New substrates were prepared by using sol-gel process for metal oxide (MgO and TiO{sub 2}) undercoating and by using chemical reduction method for silver coating. The substrates were found to exhibit strong Surface-Enhanced Raman Scattering (SERS) signals for benzoic acid (BA), terephthalic acid (TPA), p-nitrobenzoic acid (PNBA), p-aminobenzoic acid (PABA), p-nitrophenol (PNP), and p-nitroanaline. Optimization of metal oxide undercoating and silver deposition was conducted to obtain intense SER band of BA. It was shown that the substrates could be reused for the SER investigation of different samples. A study of the solvent effect on the SERS intensity of BA was conducted; an explanation to the result was suggested.

  17. Chlorophyll enhances oxidative stress tolerance in Caenorhabditis elegans and extends its lifespan

    PubMed Central

    Wang, Erjia

    2016-01-01

    Green vegetables are thought to be responsible for several beneficial properties such as antioxidant, anti-mutagenic, and detoxification activities. It is not known whether these effects are due to chlorophyll which exists in large amounts in many foods or result from other secondary metabolites. In this study, we used the model system Caenorhabditis elegans to investigate the anti-oxidative and anti-aging effects of chlorophyll in vivo. We found that chlorophyll significantly improves resistance to oxidative stress. It also enhances the lifespan of C. elegans by up to 25% via activation of the DAF-16/FOXO-dependent pathway. The results indicate that chlorophyll is absorbed by the worms and is thus bioavailable, constituting an important prerequisite for antioxidant and longevity-promoting activities inside the body. Our study thereby supports the view that green vegetables may also be beneficial for humans. PMID:27077003

  18. Microshell Arrays Enhanced Sensitivity in Detection of Specific Antibody for Reduced Graphene Oxide Optical Sensor

    PubMed Central

    Jiang, Wen-Shuai; Xin, Wei; Chen, Shao-Nan; Li, Cun-Bo; Gao, Xiao-Guang; Pan, Lei-Ting; Liu, Zhi-Bo; Tian, Jian-Guo

    2017-01-01

    Protein-protein interactions play an important role in the investigation of biomolecules. In this paper, we reported on the use of a reduced graphene oxide microshell (RGOM)-based optical biosensor for the determination of goat anti-rabbit IgG. The biosensor was prepared through a self-assembly of monolayers of monodisperse polystyrene microspheres, combined with a high-temperature reduction, in order to decorate the RGOM with rabbit IgG. The periodic microshells allowed a simpler functionalization and modification of RGOM with bioreceptor units, than reduced graphene oxide (RGO). With additional antibody-antigen binding, the RGOM-based biosensor achieved better real-time and label-free detection. The RGOM-based biosensor presented a more satisfactory response to goat anti-rabbit IgG than the RGO-based biosensor. This method is promising for immobilizing biomolecules on graphene surfaces and for the fabrication of biosensors with enhanced sensitivity. PMID:28125011

  19. [Surface-enhanced Raman spectra of oxidation damnification of fetal bovine serum by ozone].

    PubMed

    Zou, Zu-Quan; Liu, Yan-Nan; Wu, Ying; Li, Qi-Nan; Chen, Mei-Zong; Sun, Hai-Ying; Lee, Imshik

    2007-06-01

    Fetal bovine serum was treated by ozone for 1 hour and 3 hours before getting its surface-enhanced Raman spectra from 200 to 1 800 cm(-1). Treated with ozone for 1 hour, it shows a significant decrease in band intensity. Treated with ozone for 3 hours, the band intensity has a further decrease but not so obviously, which means that oxidation of ozone is short lived. Treated with ozone, the orderly conformations of main chains in protein such as alpha-helix, beta-sheet and beta-corner are damaged seriously. Aromatic side chains and C-S of Cys and Met also are damnified greatly. All this means that strong oxidation of ozone results in denaturation, conformational changes and even degradation in protein.

  20. l-Arginine Enhances Resistance against Oxidative Stress and Heat Stress in Caenorhabditis elegans

    PubMed Central

    Ma, Heran; Ma, Yudan; Zhang, Zhixian; Zhao, Ziyuan; Lin, Ran; Zhu, Jinming; Guo, Yi; Xu, Li

    2016-01-01

    The antioxidant properties of l-arginine (l-Arg) in vivo, and its effect on enhancing resistance to oxidative stress and heat stress in Caenorhabditis elegans were investigated. C. elegans, a worm model popularly used in molecular and developmental biology, was used in the present study. Here, we report that l-Arg, at a concentration of 1 mM, prolonged C. elegans life by 26.98% and 37.02% under oxidative and heat stress, respectively. Further experiments indicated that the longevity-extending effects of l-Arg may be exerted by its free radical scavenging capacity and the upregulation of aging-associated gene expression in worms. This work is important in the context of numerous recent studies that concluded that environment stresses are associated with an increased population death rate. PMID:27690079

  1. Base-enhanced catalytic water oxidation by a carboxylate–bipyridine Ru(II) complex

    PubMed Central

    Song, Na; Concepcion, Javier J.; Binstead, Robert A.; Rudd, Jennifer A.; Vannucci, Aaron K.; Dares, Christopher J.; Coggins, Michael K.; Meyer, Thomas J.

    2015-01-01

    In aqueous solution above pH 2.4 with 4% (vol/vol) CH3CN, the complex [RuII(bda)(isoq)2] (bda is 2,2′-bipyridine-6,6′-dicarboxylate; isoq is isoquinoline) exists as the open-arm chelate, [RuII(CO2-bpy-CO2−)(isoq)2(NCCH3)], as shown by 1H and 13C-NMR, X-ray crystallography, and pH titrations. Rates of water oxidation with the open-arm chelate are remarkably enhanced by added proton acceptor bases, as measured by cyclic voltammetry (CV). In 1.0 M PO43–, the calculated half-time for water oxidation is ∼7 μs. The key to the rate accelerations with added bases is direct involvement of the buffer base in either atom–proton transfer (APT) or concerted electron–proton transfer (EPT) pathways. PMID:25848035

  2. Cuprous Sulfide/Reduced Graphene Oxide Hybrid Nanomaterials: Solvothermal Synthesis and Enhanced Electrochemical Performance

    NASA Astrophysics Data System (ADS)

    He, Zhanjun; Zhu, Yabo; Xing, Zheng; Wang, Zhengyuan

    2016-01-01

    The cuprous sulfide nanoparticles (CuS NPs)-decorated reduced graphene oxide (rGO) nanocomposites have been successfully prepared via a facile and efficient solvothermal synthesis method. Scanning electron microscopy and transmission electron microscopy images demonstrated that CuS micronspheres composed of nanosheets and distributed on the rGO layer in well-monodispersed form. Fourier-transform infrared spectroscopy analyses and x-ray photoelectron spectroscopy showed that graphene oxide (GO) had been reduced to rGO. The electrochemical performances of CuS/rGO nanocomposites were investigated by cyclic voltammetry and charge/discharge techniques, which showed that the specific capacitance of CuS/rGO nanocomposites was enhanced because of the introduction of rGO.

  3. Concentration rebound following in situ chemical oxidation in fractured clay.

    PubMed

    Mundle, Keely; Reynolds, David A; West, Michael R; Kueper, Bernard H

    2007-01-01

    A two-dimensional, transient-flow, and transport numerical model was developed to simulate in situ chemical oxidation (ISCO) of trichloroethylene and tetrachloroethylene by potassium permanganate in fractured clay. This computer model incorporates dense, nonaqueous phase liquid dissolution, reactive aquifer material, multispecies matrix diffusion, and kinetic formulations for the oxidation reactions. A sensitivity analysis for two types of parameters, hydrogeological and engineering, including matrix porosity, matrix organic carbon, fracture aperture, potassium permanganate dosage, and hydraulic gradient, was conducted. Remediation metrics investigated were the relative rebound concentrations arising from back diffusion and percent mass destroyed. No well-defined correlation was found between the magnitude of rebound concentrations during postremedy monitoring and the amount of contaminant mass destroyed during the application. Results indicate that all investigated parameters affect ISCO remediation in some form. Results indicate that when advective transport through the fracture is dominant relative to diffusive transport into the clay matrix (large System Peclet Number), permanganate is more likely to be flushed out of the system and treatment is not optimal. If the System Peclet Number is too small, indicating that diffusion into the matrix is dominant relative to advection through the fracture, permanganate does not traverse the entire fracture, leading to postremediation concentration rebound. Optimal application of ISCO requires balancing advective transport through the fracture with diffusive transport into the clay matrix.

  4. Oxidative Stress Promotes Ligand-independent and Enhanced Ligand-dependent Tumor Necrosis Factor Receptor Signaling*

    PubMed Central

    Ozsoy, Hatice Z.; Sivasubramanian, Natarajan; Wieder, Eric D.; Pedersen, Steen; Mann, Douglas L.

    2008-01-01

    Tumor necrosis factor (TNF) receptor 1 (TNFR1, p55) and 2 (TNFR2, p75) are characterized by several cysteine-rich modules in the extracellular domain, raising the possibility that redox-induced modifications of these cysteine residues might alter TNFR function. To test this possibility, we examined fluorescence resonance energy transfer (FRET) in 293T cells transfected with CFP- and YFP-tagged TNFRs exposed to the thiol oxidant diamide. Treatment with high concentrations of diamide (1 mm) resulted in an increase in the FRET signal that was sensitive to inhibition with the reducing agent dithiothreitol, suggesting that oxidative stress resulted in TNFR self-association. Treatment of cells with low concentrations of diamide (1 μm) that was not sufficient to provoke TNFR self-association resulted in increased TNF-induced FRET signals relative to the untreated cells, suggesting that oxidative stress enhanced ligand-dependent TNFR signaling. Similar findings were obtained when the TNFR1- and TNFR2-transfected cells were pretreated with a cell-impermeable oxidase, DsbA, that catalyzes disulfide bond formation between thiol groups on cysteine residues. The changes in TNFR self-association were functionally significant, because pretreating the HeLa cells and 293T cells resulted in increased TNF-induced NF-κB activation and TNF-induced expression of IκB and syndecan-4 mRNA levels. Although pretreatment with DsbA did not result in an increase in TNF binding to TNFRs, it resulted in increased TNF-induced activation of NF-κB, consistent with an allosteric modification of the TNFRs. Taken together, these results suggest that oxidative stress promotes TNFR receptor self-interaction and ligand-independent and enhanced ligand-dependent TNF signaling. PMID:18544535

  5. Probiotics enhance pancreatic glutathione biosynthesis and reduce oxidative stress in experimental acute pancreatitis.

    PubMed

    Lutgendorff, Femke; Trulsson, Lena M; van Minnen, L Paul; Rijkers, Ger T; Timmerman, Harro M; Franzén, Lennart E; Gooszen, Hein G; Akkermans, Louis M A; Söderholm, Johan D; Sandström, Per A

    2008-11-01

    Factors determining severity of acute pancreatitis (AP) are poorly understood. Oxidative stress causes acinar cell injury and contributes to the severity, whereas prophylactic probiotics ameliorate experimental pancreatitis. Our objective was to study how probiotics affect oxidative stress, inflammation, and acinar cell injury during the early phase of AP. Fifty-three male Sprague-Dawley rats were randomly allocated into groups: 1) control, 2) sham procedure, 3) AP with no treatment, 4) AP with probiotics, and 5) AP with placebo. AP was induced under general anesthesia by intraductal glycodeoxycholate infusion (15 mM) and intravenous cerulein (5 microg.kg(-1).h(-1), for 6 h). Daily probiotics or placebo were administered intragastrically, starting 5 days prior to AP. After cerulein infusion, pancreas samples were collected for analysis including lipid peroxidation, glutathione, glutamate-cysteine-ligase activity, histological grading of pancreatic injury, and NF-kappaB activation. The severity of pancreatic injury correlated to oxidative damage (r = 0.9) and was ameliorated by probiotics (1.5 vs. placebo 5.5; P = 0.014). AP-induced NF-kappaB activation was reduced by probiotics (0.20 vs. placebo 0.53 OD(450nm)/mg nuclear protein; P < 0.001). Probiotics attenuated AP-induced lipid peroxidation (0.25 vs. placebo 0.51 pmol malondialdehyde/mg protein; P < 0.001). Not only was AP-induced glutathione depletion prevented (8.81 vs. placebo 4.1 micromol/mg protein, P < 0.001), probiotic pretreatment even increased glutathione compared with sham rats (8.81 vs. sham 6.18 miccromol/mg protein, P < 0.001). Biosynthesis of glutathione (glutamate-cysteine-ligase activity) was enhanced in probiotic-pretreated animals. Probiotics enhanced the biosynthesis of glutathione, which may have reduced activation of inflammation and acinar cell injury and ameliorated experimental AP, via a reduction in oxidative stress.

  6. A novel technique using potassium permanganate and reflectance confocal microscopy to image biofilm extracellular polymeric matrix reveals non-eDNA networks in Pseudomonas aeruginosa biofilms

    PubMed Central

    Swearingen, Matthew C.; Mehta, Ajeet; Mehta, Amar; Nistico, Laura; Hill, Preston J.; Falzarano, Anthony R.; Wozniak, Daniel J.; Hall-Stoodley, Luanne; Stoodley, Paul

    2015-01-01

    Biofilms are etiologically important in the development of chronic medical and dental infections. The biofilm extracellular polymeric substance (EPS) determines biofilm structure and allows bacteria in biofilms to adapt to changes in mechanical loads such as fluid shear. However, EPS components are difficult to visualize microscopically because of their low density and molecular complexity. Here, we tested potassium permanganate, KMnO4, for use as a non-specific EPS contrast-enhancing stain using confocal laser scanning microscopy in reflectance mode. We demonstrate that KMnO4 reacted with EPS components of various strains of Pseudomonas, Staphylococcus and Streptococcus, yielding brown MnO2 precipitate deposition on the EPS, which was quantifiable using data from the laser reflection detector. Furthermore, the MnO2 signal could be quantified in combination with fluorescent nucleic acid staining. COMSTAT image analysis indicated that KMnO4 staining increased the estimated biovolume over that determined by nucleic acid staining alone for all strains tested, and revealed non-eDNA EPS networks in Pseudomonas aeruginosa biofilm. In vitro and in vivo testing indicated that KMnO4 reacted with poly-N-acetylglucosamine and Pseudomonas Pel polysaccharide, but did not react strongly with DNA or alginate. KMnO4 staining may have application as a research tool and for diagnostic potential for biofilms in clinical samples. PMID:26536894

  7. A novel technique using potassium permanganate and reflectance confocal microscopy to image biofilm extracellular polymeric matrix reveals non-eDNA networks in Pseudomonas aeruginosa biofilms.

    PubMed

    Swearingen, Matthew C; Mehta, Ajeet; Mehta, Amar; Nistico, Laura; Hill, Preston J; Falzarano, Anthony R; Wozniak, Daniel J; Hall-Stoodley, Luanne; Stoodley, Paul

    2016-02-01

    Biofilms are etiologically important in the development of chronic medical and dental infections. The biofilm extracellular polymeric substance (EPS) determines biofilm structure and allows bacteria in biofilms to adapt to changes in mechanical loads such as fluid shear. However, EPS components are difficult to visualize microscopically because of their low density and molecular complexity. Here, we tested potassium permanganate, KMnO4, for use as a non-specific EPS contrast-enhancing stain using confocal laser scanning microscopy in reflectance mode. We demonstrate that KMnO4 reacted with EPS components of various strains of Pseudomonas, Staphylococcus and Streptococcus, yielding brown MnO2 precipitate deposition on the EPS, which was quantifiable using data from the laser reflection detector. Furthermore, the MnO2 signal could be quantified in combination with fluorescent nucleic acid staining. COMSTAT image analysis indicated that KMnO4 staining increased the estimated biovolume over that determined by nucleic acid staining alone for all strains tested, and revealed non-eDNA EPS networks in Pseudomonas aeruginosa biofilm. In vitro and in vivo testing indicated that KMnO4 reacted with poly-N-acetylglucosamine and Pseudomonas Pel polysaccharide, but did not react strongly with DNA or alginate. KMnO4 staining may have application as a research tool and for diagnostic potential for biofilms in clinical samples. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  8. Novel Oxidatively Activated Agents Modify DNA and are Enhanced by Ercc1 Silencing

    PubMed Central

    Jones, Amy R.; Bell-Horwath, Tiffany R.; Li, Guorui; Rollmann, Stephanie M.; Merino, Edward J.

    2012-01-01

    Agents that chemically modify DNA form a backbone of many cancer treatments. A key problem for DNA modifying agents is lack of specificity. To address this issue, we designed novel molecular scaffolds, termed An-Hq and An-Hq2, which are activated by a hallmark of some cancers: elevated concentrations of reactive oxygen species. Elevated reactive oxygen species are linked to oncogenesis and is found to increase in several aggressive cancers. The agents are quinones that, upon oxidation, form highly electrophilic species. In vitro studies identified the mode of addition to DNA. The aniline portion of An-Hq serves to enhance nucleophilic addition to the ethyl phenyl ether instead of forming common Michael additions. Structural characterization showed the agents add to 2′-deoxyguanosine at the N2,N3-positions. The product formed is a bulky hydroxy-N2,3-benzetheno-2′-deoxyguanosine adduct. In addition, the oxidatively activated agents added to 2′-deoxyadenosine and 2′-deoxycytidine, but not thymidine or 2′-deoxyinosine. These findings are confirmed by primer extension analysis of a 392 base pair DNA. The full-length primer extension product was reduced by 69.0 ± 0.6% upon oxidative activation of An-Hq2 compared to controls. Little sequence dependence was observed with 76% of guanine, adenine, and cytosine residues showing an increase in extension stops between two and four fold above controls. Benzetheno-nucleobase addition to double stranded DNA was confirmed by LC/MS of a self-complementary oligonucletide. Experiments were carried out to confirm in vivo DNA damage. Because of the lesion identified in vitro, we reasoned that nucleotide excision repair should be involved in reversing the effects of these oxidatively activated agents and enhance toxicity in Drosophila melanogaster. Using an RNAi based approach, Ercc1 was silenced and survival monitored after injection of an agent. As expected, bulky cross-linking DNA modifying agents, cisplatin and

  9. The Dependence of the Oxidation Enhancement of InP(100) Surface on the Coverage of the Adsorbed Cs

    SciTech Connect

    Sun, Yun

    2010-06-07

    We report the oxidation of the InP(100) surface promoted by adsorbed Cs by synchrotron radiation photoemission. Oxygen exposure causes reduction of the charge transferred to the InP substrate from Cs and the growth of indium oxide and phosphorous oxide. The oxide growth displays a clear dependence on the Cs coverage. The oxidation of phosphorous is negligible up to 1000 L of O{sub 2} exposure when the Cs coverage is less than half a monolayer (ML), but the formation of the second half monolayer of Cs greatly accelerates the oxidation. This different enhancement of the InP oxidation by the first and the second half monolayer of Cs is due to the double layer structure of the adsorbed Cs atoms, and consequently the higher 6s electron density in the Cs atoms when Cs coverage is larger than 0.5 ML.

  10. Enhanced catalytic stability of lipase immobilized on oxidized and disulfide-rich eggshell membrane for esters hydrolysis and transesterification.

    PubMed

    Jiang, Chenyu; Cheng, Chuanchuan; Hao, Mei; Wang, Hongbin; Wang, Ziying; Shen, Cai; Cheong, Ling-Zhi

    2017-07-30

    Eggshell membrane (ESM) is an industrial waste that is available in abundance from food industry. Present study investigated the physicochemical properties of oxidized ESM and compared the efficiency of ESM and oxidized ESM as carrier for Burkholderia cepacia lipase (BCL) used in esters hydrolysis and transesterification. Following oxidation treatment, FTIR analysis and Ellman's assay showed amino acid cysteine in ESM was oxidized to form disulfide bond-containing cystine. In addition, AFM analysis showed ESM which exhibited a highly porous filamentous structure appeared to be coalesce following oxidation treatment. Oxidized ESM also showed reduced porosity (38.67%) in comparison to native ESM (51.65%). BCL were successfully immobilized on oxidized ESM through carrier activation method (enzyme loading of 5.01mg protein/g oxidized ESM). These immobilized lipase demonstrated significantly (P<0.05) enhanced catalytic stability with close to 100% of initial hydrolysis (12.03±0.29mmol/min/g) activity; and more than 85% of its initial transesterification (7.83±0.05) activity for at least 10 consecutive runs. Enhanced catalytic stability of BCL immobilized on oxidized ESM might be due to stabilization of the protein structure in oxidized ESM by disulfide bonds which helped formation of a stable bonding with BCL. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Surface enhanced Raman scattering of biospecies on anodized aluminum oxide films

    NASA Astrophysics Data System (ADS)

    Zhang, C.; Smirnov, A. I.; Hahn, D.; Grebel, H.

    2007-06-01

    Traditionally, aluminum and anodized aluminum oxide films (AAO) are not the platforms of choice for surface-enhanced raman scattering (SERS) experiments despite of the aluminum's large negative permittivity value. Here we examine the usefulness of aluminum and nanoporous alumina platforms for detecting soft biospecies ranging from bacterial spores to protein markers. We used these flat platforms to examine SERS of a model protein (cytochrome c from bovine heart tissue) and bacterial cells (spores of Bacillus subtilis ATCC13933 used as Anthrax simulant) and demonstrated clear Raman amplification.

  12. SnO2 nanospheres supported Pd catalyst with enhanced performance for formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Lu, Haiting; Fan, Yang; Huang, Ping; Xu, Dongli

    2012-10-01

    SnO2 nanospheres were employed as the support material for Pd catalyst. The as-prepared Pd/SnO2 catalyst exhibited remarkably improved electrocatalytic activity and stability towards formic acid oxidation, in comparison with that of the Vulcan XC-72 carbon black and the commercial SnO2 nanopowder supported Pd catalyst. The enhanced catalytic performance may arise from the unique structure and surface properties of the SnO2 nanospheres, which process extraordinary promotional effect on Pd catalyst.

  13. Nitric oxide delivery by core/shell superparamagnetic nanoparticle vehicles with enhanced biocompatibility.

    PubMed

    Zhang, X F; Mansouri, S; Mbeh, D A; Yahia, L'H; Sacher, E; Veres, T

    2012-09-04

    We report the synthesis of Fe(3)O(4)/silica core/shell nanoparticles and their functionalization with S-nitrosothiols. These nanoparticles are of immense interest because of their nitric oxide (NO) release capabilities in human alveolar epithelial cells. Moreover, they act as large storage reservoirs of NO that can be targeted magnetically to the specific site with a sustainable release of NO for up to 50 h. Such nanoparticles provide an enhancement of the biocompatibility with released NO while allowing intracellular accumulation ascribed to their small size.

  14. Multidentate oligomeric ligands to enhance the biocompatibility of iron oxide and other metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Wang, Wentao; Palui, Goutam; Ji, Xin; Aldeek, Fadi; Mattoussi, Hedi

    2014-03-01

    We prepared a set of multi-coordinating and reactive amphiphilic polymer ligands and used them for surface-functionalizing magnetic iron oxide nanoparticles. The amphiphilic oligomers were prepared by coupling (via one step nucleophilic addition) several dopamine anchoring groups, polyethylene glycol moieties and reactive groups onto a poly(isobutylene-alt-maleic anhydride) chain. The availability of several anchoring groups in the same ligand greatly enhances the ligand affinity to the nanoparticle surfaces, via multiplecoordination, while the hydrophilic and reactive groups promote colloidal stability in buffer media and allow subsequent conjugation to target biomolecules. The hydrophilic nanoparticles capped with these polymers maintain compact size and exhibit great long term colloidal stability.

  15. Estrogen increases the severity of anaphylaxis in female mice through enhanced endothelial nitric oxide synthase expression and nitric oxide production.

    PubMed

    Hox, Valerie; Desai, Avanti; Bandara, Geethani; Gilfillan, Alasdair M; Metcalfe, Dean D; Olivera, Ana

    2015-03-01

    Clinical observations suggest that anaphylaxis is more common in adult women compared with adult men, although the mechanistic basis for this sex bias is not well understood. We sought to document sex-dependent differences in a mouse model of anaphylaxis and explore the role of female sex hormones and the mechanisms responsible. Passive systemic anaphylaxis was induced in female and male mice by using histamine, as well as IgE or IgG receptor aggregation. Anaphylaxis was assessed by monitoring body temperature, release of mast cell mediators and/or hematocrit, and lung weight as a measure of vascular permeability. A combination of ovariectomy, estrogen receptor antagonism, and estrogen administration techniques were used to establish estrogen involvement. Anaphylactic responses were more pronounced in female than male mice. The enhanced severity of anaphylaxis in female mice was eliminated after pretreatment with an estrogen receptor antagonist or ovariectomy but restored after administration of estradiol in ovariectomized mice, demonstrating that the sex-specific differences are due to the female steroid estradiol. Estrogen did not affect mast cell responsiveness or anaphylaxis onset. Instead, it increased tissue expression of endothelial nitric oxide synthase (eNOS). Blockage of NOS activity with the inhibitor L-NG-nitroarginine methyl ester or genetic eNOS deficiency abolished the sex-related differences. Our study defines a contribution of estrogen through its regulation of eNOS expression and nitric oxide production to vascular hyperpermeability and intensified anaphylactic responses in female mice, providing additional mechanistic insights into risk factors and possible implications for clinical management in the further exploration of human anaphylaxis. Published by Elsevier Inc.

  16. The surface and electrochemical analysis of permanganate based conversion coating on alclad and unclad 2024 alloy

    NASA Astrophysics Data System (ADS)

    Yoganandan, G.; Balaraju, J. N.; William Grips, V. K.

    2012-09-01

    In the present investigation permanganate based conversion coating (PCC) was developed on AA 2024 alloy using alkaline bath containing Mn/Mo oxyanions. Conversion coating was formed on alclad (APCC) and unclad (UPCC) aluminium alloys by simple immersion method. Surface morphology of the APCC and UPCC specimens exhibited smooth and mud-crack patterns respectively. Elemental analysis showed the presence of higher amounts of Mn (5-6 wt.%) and Mo (0.3 wt.%) on UPCC. Raman and XPS analysis showed the presence of compounds such as MnOx (Mn3O4 and Mn2O3), MnO2, KMnO4, MoOx, MoO2, MoO3/polymolybdate on both coating surfaces. The corrosion current density (icorr) values obtained for both coated surfaces were less than 1 μA/cm2. However, APCC specimen showed the lowest icorr value of about 0.05 μA/cm2 after 168 h of immersion in 3.5% NaCl. EIS studies revealed the higher charge transfer resistance (Rct) values for APCC specimen after 1 and 168 h immersion compared to UPCC. Coated specimens were also tested by continuous salt spray exposure (ASTM B117) with and without cross-hatch mark ('X') for about 750 h. Coating discoloration along with the presence of few corrosion products had been noticed on UPCC specimen after continuous salt spray exposure.

  17. Chemiluminescence detection of permanganate index (CODMn) by a luminol-KMnO4 based reaction.

    PubMed

    Tian, Jinjun; Hu, Yonggang; Zhang, Jie

    2008-01-01

    A novel chemiluminescence (CL) system for determination of permanganate index (CODMn) combined with flow injection analysis has been proposed in this study. On the basis of the chemiluminescent reaction of luminol-KMnO4 system, light emission caused by luminol-KMnO4 system was detected by the photomultiplier tube, and its intensity caused by the appearance of KMnO4 after sample digestion was inversely proportional to CODMn. Effects for CODMn determining such as pH, concentrations and interference were investigated in detail. A detection limit of 0.3 mg/L CODMn with a linear range of 0.3--200 mg/L for its theoretical CODMn was obtained under the optimized experimental conditions. The relative standard deviation was 4.3% for 5.0 mg/L CODMn (n = 11). This CL flow system for determining CODMn was simple, rapid, and suitable for automatic analysis. The data obtained by the present method were fairly in good agreement with those obtained by the standard titrimetric method. It has been applied to determine real samples with satisfactory results.

  18. Application of potassium permanganate to spectrophotometric assay of metoclopramide hydrochloride in pharmaceuticals

    NASA Astrophysics Data System (ADS)

    Devi, O. Zenita; Basavaiah, K.; Vinay, K. B.

    2012-01-01

    Two simple, sensitive, and cost-effective spectrophotometric methods are described for the determination of metoclopramide hydrochloride (MCP) in pharmaceutical dosage forms. The methods are based on a redox reaction between MCP and KMnO4 in alkaline and acid media. Direct spectrophotometry (method A) involves treating MCP with permanganate in an NaOH medium and measuring a bluish green product at 610 nm. In indirect spectrophotometry (method B), MCP is treated with a fixed concentration of KMnO4 in an H2SO4 medium, and after a specified time, the unreacted KMnO4 is measured at 545 nm. Under optimum assay conditions, Beer's law is obeyed over the ranges of 0.75-12.0 and 2.5-30.0 g/ml for methods A and B, respectively. Molar absorptivity values are calculated to be 2.33•104 and 2.66•104 l/mol cm for methods A and B, respectively, and corresponding Sandell's sensitivity values are 0.015 and 0.013 g/cm2. Limits of detection (LOD) and quantification (LOQ) are also reported. The applicability of the developed methods was demonstrated by the determination of MCP in tablet and injection forms. The accuracy and reliability of the proposed methods were further ascertained by recovery studies via standard addition technique.

  19. Acidic Potassium Permanganate Chemiluminescence for the Determination of Antioxidant Potential in Three Cultivars of Ocimum basilicum.

    PubMed

    Srivastava, Shivani; Adholeya, Alok; Conlan, Xavier A; Cahill, David M

    2016-03-01

    Ocimum basilicum, a member of the family Lamiaceae, is a rich source of polyphenolics that have antioxidant properties. The present study describes the development and application of an online HPLC-coupled acidic potassium permanganate chemiluminescence assay for the qualitative and quantitative assessment of antioxidants in three cultivars of O. basilicum grown under greenhouse conditions. The chemiluminescence based assay was found to be a sensitive and efficient method for assessment of total and individual compound antioxidant potential. Leaves, flowers and roots were found to be rich reserves of the antioxidant compounds which showed intense chemiluminescence signals. The polyphenolics such as rosmarinic, chicoric, caffeic, p-coumaric, m-coumaric and ferulic acids showed antioxidant activity. Further, rosmarinic acid was found to be the major antioxidant component in water-ethanol extracts. The highest levels of rosmarinic acid was found in the leaves and roots of cultivars "holy green" (14.37; 11.52 mM/100 g DW respectively) followed by "red rubin" (10.02; 10.75 mM/100 g DW respectively) and "subja" (6.59; 4.97 mM/100 g DW respectively). The sensitivity, efficiency and ease of use of the chemiluminescence based assay should now be considered for its use as a primary method for the identification and quantification of antioxidants in plant extracts.

  20. Model creation of moving redox reaction boundary in agarose gel electrophoresis by traditional potassium permanganate method.

    PubMed

    Xie, Hai-Yang; Liu, Qian; Li, Jia-Hao; Fan, Liu-Yin; Cao, Cheng-Xi

    2013-02-21

    A novel moving redox reaction boundary (MRRB) model was developed for studying electrophoretic behaviors of analytes involving redox reaction on the principle of moving reaction boundary (MRB). Traditional potassium permanganate method was used to create the boundary model in agarose gel electrophoresis because of the rapid reaction rate associated with MnO(4)(-) ions and Fe(2+) ions. MRB velocity equation was proposed to describe the general functional relationship between velocity of moving redox reaction boundary (V(MRRB)) and concentration of reactant, and can be extrapolated to similar MRB techniques. Parameters affecting the redox reaction boundary were investigated in detail. Under the selected conditions, good linear relationship between boundary movement distance and time were obtained. The potential application of MRRB in electromigration redox reaction titration was performed in two different concentration levels. The precision of the V(MRRB) was studied and the relative standard deviations were below 8.1%, illustrating the good repeatability achieved in this experiment. The proposed MRRB model enriches the MRB theory and also provides a feasible realization of manual control of redox reaction process in electrophoretic analysis.

  1. Metalorganic precursor decomposition and oxidation mechanisms in plasma-enhanced ZrO2 deposition

    NASA Astrophysics Data System (ADS)

    Cho, Byeong-Ok; Wang, Jianjun; Chang, Jane P.

    2002-10-01

    We investigated the gas phase reaction mechanisms in the ZrO2-deposition plasma using zirconium tert-butoxide (ZTB) as a metalorganic precursor, Ar as a carrier of the ZTB vapor, and O2 as an oxidant using quadrupole mass spectrometry (QMS). Zirconium containing ions including Zr+, ZrO+, ZrO2H+, ZrO3H3+, and ZrO4H5+ were clearly observed in the plasma, and ions of higher zirconium oxidation states become progressively favored at higher O2-to-ZTB carrying Ar flow rate ratio (O2/Ar), increased chamber pressure, and decreased microwave power. The average oxidation state calculated from the partition of ZrOxHy+ varied from 0.5 to 2.1 in the process range covering O2/Ar of 0 to 4, pressure of 5 to 40 mTorr, and power of 150 to 700 W. Based on the QMS analyses, we proposed two main opposing reaction paths responsible for the complex gas phase reactions, i.e., serial dissociations and serial oxidations. The increase in the electron temperature and density resulted in the shift of ZrOxHy+ to lower oxidation states by enhancing the dissociation of Zr-O bond and by depleting oxygen through gas phase reactions. The repartitioning of the ZrOxHy+ species was also contributed by their different Zr-O dissociation energies. To ascertain the effect of various process variables, we monitored the time evolutions of O2+ and ZrOxHy+ intensities as we abruptly change a process variable: the chemical effect (O2/Ar) led to gradual changes in their intensities, whereas physical effects (pressure and power) caused an abrupt step change in accordance with an instant response of the plasma electrons.

  2. Synergism between rhinovirus infection and oxidant pollutant exposure enhances airway epithelial cell cytokine production.

    PubMed Central

    Spannhake, E William; Reddy, Sekhar P M; Jacoby, David B; Yu, Xiao-Ying; Saatian, Bahman; Tian, Jingyan

    2002-01-01

    Of the several factors believed to exacerbate asthmatic symptoms, air pollution and viral infections are considered to be particularly important. Although evidence indicates that each of these respiratory insults individually can increase asthma severity in susceptible individuals, we know little about the extent to which exposure to environmental oxidant pollutants can influence the course of respiratory viral infection and its associated inflammation. To investigate the interaction of these two stimuli within their common epithelial cell targets in the upper and lower respiratory tracks, we infected primary human nasal epithelial cells and cells of the BEAS-2B line grown at the air-liquid interface with human rhinovirus type 16 (RV16) and exposed them to NO2 (2.0 ppm) or O3 (0.2 ppm) for 3 hr. Independently, RV16, NO2, and O3 rapidly increased release of the inflammatory cytokine interleukin-8 through oxidant-dependent mechanisms. The combined effect of RV16 and oxidant ranged from 42% to 250% greater than additive for NO2 and from 41% to 67% for O3. We abrogated these effects by treating the cells with the antioxidant N-acetylcysteine. Surface expression of intercellular adhesion molecule 1 (ICAM-1) underwent additive enhancement in response to combined stimulation. These data indicate that oxidant pollutants can amplify the generation of proinflammatory cytokines by RV16-infected cells and suggest that virus-induced inflammation in upper and lower airways may be exacerbated by concurrent exposure to ambient levels of oxidants commonly encountered the indoor and outdoor environments. PMID:12117643

  3. Micro/nanostructured porous Fe-Ni binary oxide and its enhanced arsenic adsorption performances.

    PubMed

    Liu, Shengwen; Kang, Shenghong; Wang, Guozhong; Zhao, Huijun; Cai, Weiping

    2015-11-15

    A simple method is presented to synthesize micro/nano-structured Fe-Ni binary oxides based on co-precipitation and subsequent calcination. It has been found that the Fe-Ni binary oxides are composed of the porous microsized aggregates built with nanoparticles. When the atomic ratio of Fe to Ni is 2 to 1 the binary oxide is the micro-scaled aggregates consisting of the ultrafine NiFe2O4 nanoparticles with 3-6nm in size, and shows porous structure with pore diameter of 3nm and a specific surface area of 245m(2)g(-1). Such material is of abundant surface functional groups and has exhibited high adsorption performance to As(III) and As(V). The kinetic adsorption can be described by pseudo-second order model and the isothermal adsorption is subject to Langmuir model. The maximum adsorption capacity on such Fe-Ni porous binary oxide is up to 168.6mgg(-1) and 90.1mgg(-1) for As(III) and As(V), respectively, which are much higher than the arsenic adsorption capacity for most commercial adsorbents. Such enhanced adsorption ability for this material is mainly attributed to its porous structure and high specific surface area as well as the abundant surface functional groups. Further experiments have revealed that the influence of the anions such as sulfate, carbonate, and phosphate, which commonly co-exist in water, on the arsenic adsorption is insignificant, exhibiting strong adsorption selectivity to arsenic. This micro/nano-structured porous Fe-Ni binary oxide is hence of good practicability to be used as a highly efficient adsorbent for arsenic removal from the real arsenic-contaminated waters. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Photoelectrochemical water splitting enhanced by self-assembled metal nanopillars embedded in an oxide semiconductor photoelectrode

    PubMed Central

    Kawasaki, Seiji; Takahashi, Ryota; Yamamoto, Takahisa; Kobayashi, Masaki; Kumigashira, Hiroshi; Yoshinobu, Jun; Komori, Fumio; Kudo, Akihiko; Lippmaa, Mikk

    2016-01-01

    Production of chemical fuels by direct solar energy conversion in a photoelectrochemical cell is of great practical interest for developing a sustainable energy system. Various nanoscale designs such as nanowires, nanotubes, heterostructures and nanocomposites have been explored to increase the energy conversion efficiency of photoelectrochemical water splitting. Here we demonstrate a self-organized nanocomposite material concept for enhancing the efficiency of photocarrier separation and electrochemical energy conversion. Mechanically robust photoelectrodes are formed by embedding self-assembled metal nanopillars in a semiconductor thin film, forming tubular Schottky junctions around each pillar. The photocarrier transport efficiency is strongly enhanced in the Schottky space charge regions while the pillars provide an efficient charge extraction path. Ir-doped SrTiO3 with embedded iridium metal nanopillars shows good operational stability in a water oxidation reaction and achieves over 80% utilization of photogenerated carriers under visible light in the 400- to 600-nm wavelength range. PMID:27255209

  5. Enhanced dark hydrogen fermentation by addition of ferric oxide nanoparticles using Enterobacter aerogenes.

    PubMed

    Lin, Richen; Cheng, Jun; Ding, Lingkan; Song, Wenlu; Liu, Min; Zhou, Junhu; Cen, Kefa

    2016-05-01

    Ferric oxide nanoparticles (FONPs) were used to facilitate dark hydrogen fermentation using Enterobacter aerogenes. The hydrogen yield of glucose increased from 164.5±2.29 to 192.4±1.14mL/g when FONPs concentration increased from 0 to 200mg/L. SEM images of E. aerogenes demonstrated the existence of bacterial nanowire among cells, suggesting FONPs served as electron conduits to enhance electron transfer. TEM showed cellular internalization of FONPs, indicating hydrogenase synthesis and activity was potentially promoted due to the released iron element. When further increasing FONPs concentration to 400mg/L, the hydrogen yield of glucose decreased to 147.2±2.54mL/g. Soluble metabolic products revealed FONPs enhanced acetate pathway of hydrogen production, but weakened ethanol pathway. This shift of metabolic pathways allowed more nicotinamide adenine dinucleotide for reducing proton to hydrogen.

  6. Pd Nanoparticles Coupled to WO2.72 Nanorods for Enhanced Electrochemical Oxidation of Formic Acid.

    PubMed

    Xi, Zheng; Erdosy, Daniel P; Mendoza-Garcia, Adriana; Duchesne, Paul N; Li, Junrui; Muzzio, Michelle; Li, Qing; Zhang, Peng; Sun, Shouheng

    2017-04-12

    We synthesize a new type of hybrid Pd/WO2.72 structure with 5 nm Pd nanoparticles (NPs) anchored on 50 × 5 nm WO2.72 nanorods. The strong Pd/WO2.72 coupling results in the lattice expansion of Pd from 0.23 to 0.27 nm and the decrease of Pd surface electron density. As a result, the Pd/WO2.72 shows much enhanced catalysis toward electrochemical oxidation of formic acid in 0.1 M HClO4; it has a mass activity of ∼1600 mA/mgPd in a broad potential range of 0.4-0.85 V (vs RHE) and shows no obvious activity loss after a 12 h chronoamperometry test at 0.4 V. Our work demonstrates an important strategy to enhance Pd NP catalyst efficiency for energy conversion reactions.

  7. Graphene oxide embedded sandwich nanostructures for enhanced Raman readout and their applications in pesticide monitoring

    NASA Astrophysics Data System (ADS)

    Zhang, Lulu; Jiang, Changlong; Zhang, Zhongping

    2013-04-01

    Analytical techniques based on surface-enhanced Raman scattering (SERS) suffer from a lack of reproducibility and reliability, thus hampering their practical applications. Herein, we have developed a SERS-active substrate based on a graphene oxide embedded sandwich nanostructure for ultrasensitive Raman signal readout. By using this novel Au@Ag NPs/GO/Au@Ag NPs sandwich nanostructure as a SERS substrate, the Raman signals of analytes were dramatically enhanced due to having plenty of hot spots on their surfaces and the unique structure of the graphene oxide sheets. These features make the sandwich nanostructured film an ideal SERS substrate to improve the sensitivity, reproducibility and reliability of the Raman readout. The sandwich nanostructure film can be applied to detect rhodamine-6G (R6G) with an enhancement factor (EF) of ~7.0 × 107 and the pesticide thiram in commercial grape juice with a detection limit of as low as 0.1 μM (0.03 ppm), which is much lower than the maximal residue limit (MRL) of 7 ppm in fruit prescribed by the U.S. Environmental Protection Agency (EPA). The GO embedded sandwich nanostructure also has the ability to selectively detect dithiocarbamate compounds over other types of agricultural chemical. Furthermore, spiked tests show that the sandwich nanostructure can be used to monitor thiram in natural lake water and commercial grape juice without further treatment. In addition, the GO enhanced Raman spectroscopic technique offers potential practical applications for the on-site monitoring and assessment of pesticide residues in agricultural products and environments.Analytical techniques based on surface-enhanced Raman scattering (SERS) suffer from a lack of reproducibility and reliability, thus hampering their practical applications. Herein, we have developed a SERS-active substrate based on a graphene oxide embedded sandwich nanostructure for ultrasensitive Raman signal readout. By using this novel Au@Ag NPs/GO/Au@Ag NPs sandwich

  8. Tin Oxide-Carbon-Coated Sepiolite Nanofibers with Enhanced Lithium-Ion Storage Property.

    PubMed

    Hou, Kai; Wen, Xin; Yan, Peng; Tang, Aidong; Yang, Huaming

    2017-12-01

    Natural sepiolite (Sep) nanofibers were coated with carbon and nanoscale SnO2 to prepare an emerging nanocomposite (SnO2-C@Sep), which exhibited enhanced electrochemical performance. Sepiolite could act as a steady skeleton, carbon coating principally led sepiolite from an isolated to an electric state, and decoration of nanoscale SnO2 was beneficial to the functionization of sepiolite. Cycling performances indicated that SnO2-C@Sep showed higher discharge capacities than commercial SnO2 after 50 cycles. The nanocomposite SnO2-C@Sep possessed enhanced lithium storage properties with stable capacity retention and low cost, which could open up a new strategy to synthesize a variety of functional hybrid materials based on the cheap and abundant clay and commercialization of lithium-metal oxide batteries.

  9. Tin Oxide-Carbon-Coated Sepiolite Nanofibers with Enhanced Lithium-Ion Storage Property

    NASA Astrophysics Data System (ADS)

    Hou, Kai; Wen, Xin; Yan, Peng; Tang, Aidong; Yang, Huaming

    2017-03-01

    Natural sepiolite (Sep) nanofibers were coated with carbon and nanoscale SnO2 to prepare an emerging nanocomposite (SnO2-C@Sep), which exhibited enhanced electrochemical performance. Sepiolite could act as a steady skeleton, carbon coating principally led sepiolite from an isolated to an electric state, and decoration of nanoscale SnO2 was beneficial to the functionization of sepiolite. Cycling performances indicated that SnO2-C@Sep showed higher discharge capacities than commercial SnO2 after 50 cycles. The nanocomposite SnO2-C@Sep possessed enhanced lithium storage properties with stable capacity retention and low cost, which could open up a new strategy to synthesize a variety of functional hybrid materials based on the cheap and abundant clay and commercialization of lithium-metal oxide batteries.

  10. Surface-enhanced infrared spectroscopy using metal oxide plasmonic antenna arrays.

    PubMed

    Abb, Martina; Wang, Yudong; Papasimakis, Nikitas; de Groot, C H; Muskens, Otto L

    2014-01-08

    We successfully demonstrate surface-enhanced infrared spectroscopy using arrays of indium tin oxide (ITO) plasmonic nanoantennas. The ITO antennas show a strongly reduced plasmon wavelength, which holds promise for ultracompact antenna arrays and extremely subwavelength metamaterials. The strong plasmon confinement and reduced antenna cross section allows ITO antennas to be integrated at extremely high densities with no loss in performance due to long-range transverse interactions. By further reducing the spacing of antennas in the arrays, we access the regime of plasmonic near field coupling where the response is enhanced for both Au and ITO devices. Ultracompact ITO antennas with high spatial and spectral selectivity in spectroscopic applications offer a viable new platform for infrared plasmonics, which may be combined with other functionalities of these versatile materials in devices.

  11. Combinations of solid oxide fuel cell and several enhanced gas turbine cycles

    NASA Astrophysics Data System (ADS)

    Kuchonthara, Prapan; Bhattacharya, Sankar; Tsutsumi, Atsushi

    Combined power generation systems with combinations of solid oxide fuel cell (SOFC) and various enhanced gas turbine (GT) cycles were evaluated. In the GT part, steam injected gas turbine (STIG) cycle, GT/steam turbine (ST) combined cycle, and humid air turbine (HAT) cycle were considered. Moreover, additional recuperation was considered by means of air preheating (APH) in the STIG cycle. Effects of operating turbine inlet temperature (TIT) and pressure ratio (PR) on overall system performance were assessed. Although the SOFC-HAT system shows the lowest specific work output compared to other systems, its highest thermal efficiency presents a significant advantage. Furthermore, at high TITs and PRs the SOFC-HAT system gives the best performance in terms of both thermal efficiency and specific work. Results indicate that energy recuperative features in the HAT promote the positive effect of increasing TIT by means of enhancing GT efficiency, leading to the improvement in thermal efficiency of the overall system.

  12. Photoelectrochemical water splitting enhanced by self-assembled metal nanopillars embedded in an oxide semiconductor photoelectrode

    NASA Astrophysics Data System (ADS)

    Kawasaki, Seiji; Takahashi, Ryota; Yamamoto, Takahisa; Kobayashi, Masaki; Kumigashira, Hiroshi; Yoshinobu, Jun; Komori, Fumio; Kudo, Akihiko; Lippmaa, Mikk

    2016-06-01

    Production of chemical fuels by direct solar energy conversion in a photoelectrochemical cell is of great practical interest for developing a sustainable energy system. Various nanoscale designs such as nanowires, nanotubes, heterostructures and nanocomposites have been explored to increase the energy conversion efficiency of photoelectrochemical water splitting. Here we demonstrate a self-organized nanocomposite material concept for enhancing the efficiency of photocarrier separation and electrochemical energy conversion. Mechanically robust photoelectrodes are formed by embedding self-assembled metal nanopillars in a semiconductor thin film, forming tubular Schottky junctions around each pillar. The photocarrier transport efficiency is strongly enhanced in the Schottky space charge regions while the pillars provide an efficient charge extraction path. Ir-doped SrTiO3 with embedded iridium metal nanopillars shows good operational stability in a water oxidation reaction and achieves over 80% utilization of photogenerated carriers under visible light in the 400- to 600-nm wavelength range.

  13. Synthesis of copper doped Zinc oxide nanowires with enhanced ultraviolet photoresponse behavior

    NASA Astrophysics Data System (ADS)

    Ghosh, S. P.; Das, K. C.; Tripathy, N.; Moharana, A.; Adhikari, A.; Bo