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Sample records for californium oxides

  1. Californium-252 progress, report No. 7, April 1971

    Energy Technology Data Exchange (ETDEWEB)

    1971-12-31

    This report contains discusses of the following topics on Californium-252: First sales of californium-252; encapsulation services discussed; three new participants in market evaluation program; summer training programs to use californium; Californium-252 shipping casks available; Californium-252 questions and answers, radiotherapy; neutron radiography; natural resources exploration; nuclear safeguards; process control; dosimetry; neutron radiography; neutron shielding; and nuclear safeguards.

  2. Historical review of californium-252 discovery and development

    Science.gov (United States)

    Stoddard, D. H.

    This paper discusses the discovery and history of californium 252. This isotope may be synthesized by irradiating plutonium 239, plutonium 242, americium 243, or curium 244 with neutrons in a nuclear reactor. Various experiments and inventions involving (252)Cf conducted at the Savannah River Plant are discussed. The evolution of radiotherapy using californium 252 is reviewed.

  3. Californium-252: a remarkable versatile radioisotope

    Energy Technology Data Exchange (ETDEWEB)

    Osborne-Lee, I.W.; Alexander, C.W.

    1995-10-10

    A product of the nuclear age, Californium-252 ({sup 252}Cf) has found many applications in medicine, scientific research, industry, and nuclear science education. Californium-252 is unique as a neutron source in that it provides a highly concentrated flux and extremely reliable neutron spectrum from a very small assembly. During the past 40 years, {sup 252}Cf has been applied with great success to cancer therapy, neutron radiography of objects ranging from flowers to entire aircraft, startup sources for nuclear reactors, fission activation for quality analysis of all commercial nuclear fuel, and many other beneficial uses, some of which are now ready for further growth. Californium-252 is produced in the High Flux Isotope Reactor (HFIR) and processed in the Radiochemical Engineering Development Center (REDC), both of which are located at the Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee. The REDC/HFIR facility is virtually the sole supplier of {sup 252}Cf in the western world and is the major supplier worldwide. Extensive exploitation of this product was made possible through the {sup 252}Cf Market Evaluation Program, sponsored by the United States Department of Energy (DOE) [then the Atomic Energy Commission (AEC) and later the Energy Research and Development Administration (ERDA)]. This program included training series, demonstration centers, seminars, and a liberal loan policy for fabricated sources. The Market Evaluation Program was instituted, in part, to determine if large-quantity production capability was required at the Savannah River Laboratory (SRL). Because of the nature of the product and the means by which it is produced, {sup 252}Cf can be produced only in government-owned facilities. It is evident at this time that the Oak Ridge research facility can meet present and projected near-term requirements. The production, shipment, and sales history of {sup 252}Cf from ORNL is summarized herein.

  4. Production, Distribution, and Applications of Californium-252 Neutron Sources

    Energy Technology Data Exchange (ETDEWEB)

    Balo, P.A.; Knauer, J.B.; Martin, R.C.

    1999-10-03

    The radioisotope {sup 252}Cf is routinely encapsulated into compact, portable, intense neutron sources with a 2.6-year half-life. A source the size of a person's little finger can emit up to 10{sup 11} neutrons/s. Californium-252 is used commercially as a reliable, cost-effective neutron source for prompt gamma neutron activation analysis (PGNAA) of coal, cement, and minerals, as well as for detection and identification of explosives, laud mines, and unexploded military ordnance. Other uses are neutron radiography, nuclear waste assays, reactor start-up sources, calibration standards, and cancer therapy. The inherent safety of source encapsulations is demonstrated by 30 years of experience and by U.S. Bureau of Mines tests of source survivability during explosions. The production and distribution center for the U. S Department of Energy (DOE) Californium Program is the Radiochemical Engineering Development Center (REDC) at Oak Ridge National Laboratory (ORNL). DOE sells The radioisotope {sup 252}Cf is routinely encapsulated into compact, portable, intense neutron sources with a 2.6- year half-life. A source the size of a person's little finger can emit up to 10 neutrons/s. Californium-252 is used commercially as a reliable, cost-effective neutron source for prompt gamma neutron activation analysis (PGNAA) of coal, cement, and minerals, as well as for detection and identification of explosives, laud mines, and unexploded military ordnance. Other uses are neutron radiography, nuclear waste assays, reactor start-up sources, calibration standards, and cancer therapy. The inherent safety of source encapsulations is demonstrated by 30 years of experience and by U.S. Bureau of Mines tests of source survivability during explosions. The production and distribution center for the U. S Department of Energy (DOE) Californium Program is the Radiochemical Engineering Development Center (REDC) at Oak Ridge National Laboratory(ORNL). DOE sells {sup 252}Cf to commercial

  5. Unusual structure, bonding and properties in a californium borate

    Energy Technology Data Exchange (ETDEWEB)

    Polinski, Matthew J.; Garner, Edward B.; Maurice, Rémi; Planas, Nora; Stritzinger, Jared T.; Parker, T. Gannon; Cross, Justin N.; Green, Thomas D.; Alekseev, Evgeny V.; Van Cleve, Shelley M.; Depmeier, Wulf; Gagliardi, Laura; Shatruk, Michael; Knappenberger, Kenneth L.; Liu, Guokui; Skanthakumar, S.; Soderholm, Lynda; Dixon, David A.; Albrecht-Schmitt, Thomas E.

    2014-03-23

    The participation of the valence orbitals of actinides in bonding has been debated for decades. Recent experimental and computational investigations demonstrated the involvement of 6p, 6d and/or 5f orbitals in bonding. However, structural and spectroscopic data, as well as theory, indicate a decrease in covalency across the actinide series, and the evidence points to highly ionic, lanthanide-like bonding for late actinides. Here we show that chemical differentiation between californium and lanthanides can be achieved by using ligands that are both highly polarizable and substantially rearrange on complexation. A ligand that suits both of these desired properties is polyborate. We demonstrate that the 5f, 6d and 7p orbitals are all involved in bonding in a Cf(III) borate, and that large crystal-field effects are present. Synthetic, structural and spectroscopic data are complemented by quantum mechanical calculations to support these observations.

  6. Biomedical neutron research at the Californium User Facility for neutron science

    Energy Technology Data Exchange (ETDEWEB)

    Martin, R.C. [Oak Ridge National Lab., TN (United States); Byrne, T.E. [Roane State Community College, Harriman, TN (United States); Miller, L.F. [Univ. of Tennessee, Knoxville, TN (United States)

    1997-04-01

    The Californium User Facility for Neutron Science has been established at Oak Ridge National Laboratory (ORNL). The Californium User Facility (CUF) is a part of the larger Californium Facility, which fabricates and stores compact {sup 252}Cf neutron sources for worldwide distribution. The CUF can provide a cost-effective option for research with {sup 252}Cf sources. Three projects at the CUF that demonstrate the versatility of {sup 252}Cf for biological and biomedical neutron-based research are described: future establishment of a {sup 252}Cf-based neutron activation analysis system, ongoing work to produce miniature high-intensity, remotely afterloaded {sup 252}Cf sources for tumor therapy, and a recent experiment that irradiated living human lung cancer cells impregnated with experimental boron compounds to test their effectiveness for boron neutron capture therapy.

  7. Apparatus for the measurement of total body nitrogen using prompt neutron activation analysis with californium-252.

    Science.gov (United States)

    Mackie, A; Hannan, W J; Smith, M A; Tothill, P

    1988-01-01

    Details of clinical apparatus designed for the measurement of total body nitrogen (as an indicator of body protein), suitable for the critically ill, intensive-care patient are presented. Californium-252 radio-isotopic neutron sources are used, enabling a nitrogen measurement by prompt neutron activation analysis to be made in 40 min with a precision of +/- 3.2% for a whole body dose equivalent of 0.145 mSv. The advantages of Californium-252 over alternative neutron sources are discussed. A comparison between two irradiation/detection geometries is made, leading to an explanation of the geometry adopted for the apparatus. The choice of construction and shielding materials to reduce the count rate at the detectors and consequently to reduce the pile-up contribution to the nitrogen background is discussed. Salient features of the gamma ray spectroscopy system to reduce spectral distortion from pulse pile-up are presented.

  8. Safety Analysis Report for Packaging (SARP) of the Oak Ridge National Laboratory TRU Californium Shipping Container

    Energy Technology Data Exchange (ETDEWEB)

    Box, W.D.; Shappert, L.B.; Seagren, R.D.; Klima, B.B.; Jurgensen, M.C.; Hammond, C.R.; Watson, C.D.

    1980-01-01

    An analytical evaluation of the Oak Ridge National Laboratory TRU Californium Shipping Container was made in order to demonstrate its compliance with the regulations governing off-site shipment of packages that contain radioactive material. The evaluation encompassed five primary categories: structural integrity, thermal resistance, radiation shielding, nuclear criticality safety, and quality assurance. The results of this evaluation demonstrate that the container complies with the applicable regulations.

  9. Application of TSH bioindicator for studying the biological efficiency of neutrons from californium-252 source

    Energy Technology Data Exchange (ETDEWEB)

    Cebulska-Wasilewska, A.; Rekas, K. [Institute of Nuclear Physics, Cracow (Poland); Kim, J.K. [Korea Atomic Energy Research Inst., Taejon (Korea, Republic of)

    1997-12-31

    The effectiveness of neutrons from a Californium-252 source in the induction of various abnormalities in the Tradescantia clone 4430 stamen hair cells (TSH-assay) was studied. The special attention was paid to check whether any enhancement in effects caused by process of boron neutron capture is visible in the cells enriched with boron ions. Two chemicals (borax and BSH) were applied to introduce boron-10 ions into cells. Inflorescence, normal or pretreated with chemicals containing boron, were irradiated in the air with neutrons from a Cf-252 source at KAERI, Taejon, Korea. To estimate the relative biological effectiveness (RBE) in the induction of gene mutations of the neutron beam under the study, Tradescantia inflorescences, without any chemical pretreatment, were irradiated with various doses of X-rays. The ranges of radiation doses used were 0-0.1 Gy in neutrons and 0-0.5 Gy in X-rays. After the time needed to complete the postirradiation repair Tradescantia cuttings were transferred to Cracow, where screening of gene and lethal; mutations, cell cycle alterations in somatic cells have been done, and dose response relationships were figured. The maximal RBE values were estimated in the range of 4.6-6.8. Alterations of RBE value were observed; from 6.8 to 7.8 in the case of plants pretreated with 240 ppm of B-10 from borax, and 4.6 to 6.1 in the case of 400 ppm of B-10 from BSH. Results showed a slight, although statistically insignificant increase in biological efficacy of radiation from the Cf-252 source in samples pretreated with boron containing chemicals. (author)

  10. Study of the shielding for spontaneous fission sources of Californium-252; Estudio de blindaje para fuentes de fision espontanea de Californio-252

    Energy Technology Data Exchange (ETDEWEB)

    Davila R, I

    1991-06-15

    A shielding study is made to attenuate, until maximum permissible levels, the neutrons radiation and photons emitted by spontaneous fission coming from a source of Californium-252. The compound package by a database (Library DLC-23) and the ANISNW code is used, in it version for personal computer. (Author)

  11. Simulation and design of an electron beam ion source charge breeder for the californium rare isotope breeder upgrade

    Directory of Open Access Journals (Sweden)

    Clayton Dickerson

    2013-02-01

    Full Text Available An electron beam ion source (EBIS will be constructed and used to charge breed ions from the californium rare isotope breeder upgrade (CARIBU for postacceleration into the Argonne tandem linear accelerator system (ATLAS. Simulations of the EBIS charge breeder performance and the related ion transport systems are reported. Propagation of the electron beam through the EBIS was verified, and the anticipated incident power density within the electron collector was identified. The full normalized acceptance of the charge breeder with a 2 A electron beam, 0.024π  mm mrad for nominal operating parameters, was determined by simulating ion injection into the EBIS. The optics of the ion transport lines were carefully optimized to achieve well-matched ion injection, to minimize emittance growth of the injected and extracted ion beams, and to enable adequate testing of the charge bred ions prior to installation in ATLAS.

  12. Extraction of Trivalent Actinides and Lanthanides from Californium Campaign Rework Solution Using TODGA-based Solvent Extraction System

    Energy Technology Data Exchange (ETDEWEB)

    Benker, Dennis [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Delmau, Laetitia Helene [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dryman, Joshua Cory [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-07-01

    This report presents the studies carried out to demonstrate the possibility of quantitatively extracting trivalent actinides and lanthanides from highly acidic solutions using a neutral ligand-based solvent extraction system. These studies stemmed from the perceived advantage of such systems over cationexchange- based solvent extraction systems that require an extensive feed adjustment to make a low-acid feed. The targeted feed solutions are highly acidic aqueous phases obtained after the dissolution of curium targets during a californium (Cf) campaign. Results obtained with actual Cf campaign solutions, but highly diluted to be manageable in a glove box, are presented, followed by results of tests run in the hot cells with Cf campaign rework solutions. It was demonstrated that a solvent extraction system based on the tetraoctyl diglycolamide molecule is capable of quantitatively extracting trivalent actinides from highly acidic solutions. This system was validated using actual feeds from a Cf campaign.

  13. Beyond Californium-A Neutron Generator Alternative for Dosimetry and Instrument Calibration in the U.S.

    Science.gov (United States)

    Piper, Roman K; Mozhayev, Andrey V; Murphy, Mark K; Thompson, Alan K

    2017-09-01

    Evaluations of neutron survey instruments, area monitors, and personal dosimeters rely on reference neutron radiations, which have evolved from the heavy reliance on (α,n) sources to a shared reliance on (α,n) and the spontaneous fission neutrons of californium-252 (Cf). Capable of producing high dose equivalent rates from an almost point source geometry, the characteristics of Cf are generally more favorable when compared to the use of (α,n) and (γ,n) sources or reactor-produced reference neutron radiations. Californium-252 is typically used in two standardized configurations: unmoderated, to yield a fission energy spectrum; or with the capsule placed within a heavy-water moderating sphere to produce a softened spectrum that is generally considered more appropriate for evaluating devices used in nuclear power plant work environments. The U.S. Department of Energy Cf Loan/Lease Program, a longtime origin of affordable Cf sources for research, testing and calibration, was terminated in 2009. Since then, high-activity sources have become increasingly cost-prohibitive for laboratories that formerly benefited from that program. Neutron generators, based on the D-T and D-D fusion reactions, have become economically competitive with Cf and are recognized internationally as important calibration and test standards. Researchers from the National Institute of Standards and Technology and the Pacific Northwest National Laboratory are jointly considering the practicality and technical challenges of implementing neutron generators as calibration standards in the U.S. This article reviews the characteristics of isotope-based neutron sources, possible isotope alternatives to Cf, and the rationale behind the increasing favor of electronically generated neutron options. The evaluation of a D-T system at PNNL has revealed characteristics that must be considered in adapting generators to the task of calibration and testing where accurate determination of a dosimetric quantity is

  14. Californium-252 Brachytherapy Combined With External-Beam Radiotherapy for Cervical Cancer: Long-Term Treatment Results

    Energy Technology Data Exchange (ETDEWEB)

    Lei Xin; Qian Chengyuan; Qing Yi; Zhao Kewei; Yang Zhengzhou; Dai Nan; Zhong Zhaoyang; Tang Cheng; Li Zheng; Gu Xianqing; Zhou Qian; Feng Yan; Xiong Yanli; Shan Jinlu [Cancer Center, Research Institute of Surgery and Daping Hospital, Third Military Medical University, Chongqing (China); Wang Dong, E-mail: dongwang64@hotmail.com [Cancer Center, Research Institute of Surgery and Daping Hospital, Third Military Medical University, Chongqing (China)

    2011-12-01

    Purpose: To observe, by retrospective analysis, the curative effects and complications due to californium-252 ({sup 252}Cf) neutron intracavitary brachytherapy (ICBT) combined with external-beam radiotherapy (EBRT) in the treatment of cervical cancer. Methods and Materials: From February 1999 to December 2007, 696 patients with cervical cancer (Stages IB to IIIB) were treated with {sup 252}Cf-ICBT in combination of EBRT. Of all, 31 patients were at Stage IB, 104 at IIA, 363 at IIB, 64 at IIIA, and 134 at IIIB. Californium-252 ICBT was delivered at 7-12 Gy per insertion per week, with a total dose of 29-45 Gy to reference point A in three to five insertions. The whole pelvic cavity was treated with 8-MV X-ray external irradiation at 2 Gy per fraction, four times per week. After 16-38 Gy of external irradiation, the center of the whole pelvic field was blocked with a 4-cm-wide lead shield, with a total external irradiation dose of 44-56 Gy. The total treatment course was 5 to 6 weeks. Results: Overall survival rate at 3 and 5 years for all patients was 76.0% and 64.9%, respectively. Disease-free 3- and 5-year survival rates of patients were 71.2% and 58.4%, respectively. Late complications included vaginal contracture and adhesion, radiation proctitis, radiation cystitis, and inflammatory bowel, which accounted for 5.8%, 7.1%, 6.2%, and 4.9%, respectively. Univariate analysis results showed significant correlation of stage, age, histopathologic grade, and lymph node status with overall survival. Cox multiple regression analysis showed that the independent variables were stage, histopathologic grade, tumor size, and lymphatic metastasis in all patients. Conclusion: Results of this series suggest that the combined use of {sup 252}Cf-ICBT with EBRT is an effective method for treatment of cervical cancer.

  15. Long-term effects of an intracavitary treatment with californium-252 on normal tissue. [Swine, /sup 226/Ra

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, M.F.; Beamer, J.L.; Mahony, T.D.; Cross, F.T.; Lund, J.E.; Endres, G.W.R.

    1976-01-01

    About one hundred fifty swine were exposed to either radium-226 or californium-252 sources in the uterine cervix to determine an RBE for both acute and long-term effects. That value for early changes in the tissues at risk in the treatment of cervical cancer was between 6.2 and 6.8. The incidence of complications increased with time after exposure, especially among animals treated with /sup 252/Cf. Analysis of rectal injury showed that ulceration occurred frequently within a year postexposure at doses between 1600 and 2400 rad calculated at 2 cm lateral to the source midline. Fat necrosis and smooth muscle atrophy, resulting in a local rectal stricture, were delayed changes observed in some animals. The lower ureter was the site for a greater frequency of complications than the GI tract. Ureteral stricture often occurred at doses of 1200 rad from /sup 252/Cf and 7000 rad from /sup 226/Ra. Observation of delayed effects in the uterine-cervix in animals held up to 4 years postexposure indicate that the RBE for /sup 252/Cf may be increased to a value as high as 18, while repair may have even decreased it to about 5.6 in the rectum. Fifty swine are still being observed for long-term effects after doses above 800 rad from /sup 252/Cf and 5000 rad from /sup 226/Ra.

  16. Ab initio full-potential study of mechanical properties and magnetic phase stability of californium monopnictides (CfN and CfP)

    Energy Technology Data Exchange (ETDEWEB)

    Amari, S., E-mail: siham_amari@yahoo.fr [Faculté des Sciences de la Nature et de la Vie, Université Hassiba Benbouali, Chlef, 02000 (Algeria); Bouhafs, B. [Laboratoire de Modélisation et Simulation en Sciences des Matériaux, Université Djillali Liabès de Sidi Bel-Abbés, Sidi Bel-Abbés, 22000 (Algeria)

    2016-09-15

    Based on the first-principles methods, the structural, elastic, electronic, properties and magnetic ordering of californium monopnictides CfX (X = P) have been studied using the full-potential augmented plane wave plus local orbitals (FP-L/APW + lo) method within the framework of density functional theory (DFT). The electronic exchange correlation energy is described by generalized gradient approximation GGA and GGA+U (U is the Hubbard correction). The GGA+U method is applied to the rare-earth 5f states. We have calculated the lattice parameters, bulk modulii and the first pressure derivatives of the bulk modulii. The elastic properties of the studied compounds are only investigated in the most stable calculated phase. In order to gain further information, we have calculated Young’s modulus, shear modulus, anisotropy factor and Kleinman parameter by the aid of the calculated elastic constants. The results mainly show that californium monopnictides CfX (X = P) have an antiferromagnetic spin ordering. Density of states (DOS) and charge densities for both compounds are also computed in the NaCl (B1) structure.

  17. Low-Dose-Rate Californium-252 Neutron Intracavitary Afterloading Radiotherapy Combined With Conformal Radiotherapy for Treatment of Cervical Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Min [Department of Oncology, Armed Police Hospital of Hangzhou, Hangzhou, Zhejiang Province (China); Xu Hongde [Cancer Center, Armed Police Hospital of Hangzhou, Hangzhou, Zhejiang Province (China); Pan Songdan; Lin Shan; Yue Jianhua [Department of Oncology, Armed Police Hospital of Hangzhou, Hangzhou, Zhejiang Province (China); Liu Jianren, E-mail: liujianren0571@hotmail.com [Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang Province (China)

    2012-07-01

    Purpose: To study the efficacy of low-dose-rate californium-252 ({sup 252}Cf) neutron intracavitary afterloading radiotherapy (RT) combined with external pelvic RT for treatment of cervical cancer. Methods and Materials: The records of 96 patients treated for cervical cancer from 2006 to 2010 were retrospectively reviewed. For patients with tumors {<=}4 cm in diameter, external beam radiation was performed (1.8 Gy/day, five times/week) until the dose reached 20 Gy, and then {sup 252}Cf neutron intracavitary afterloading RT (once/week) was begun, and the frequency of external beam radiation was changed to four times/week. For patients with tumors >4 cm, {sup 252}Cf RT was performed one to two times before whole-pelvis external beam radiation. The tumor-eliminating dose was determined by using the depth limit of 5 mm below the mucosa as the reference point. In all patients, the total dose of the external beam radiation ranged from 46.8 to 50 Gy. For {sup 252}Cf RT, the dose delivered to point A was 6 Gy/fraction, once per week, for a total of seven times, and the total dose was 42 Gy. Results: The mean {+-} SD patient age was 54.7 {+-} 13.7 years. Six patients had disease assessed at stage IB, 13 patients had stage IIA, 49 patients had stage IIB, 3 patients had stage IIIA, 24 patients had stage IIIB, and 1 patient had stage IVA. All patients obtained complete tumor regression (CR). The mean {+-} SD time to CR was 23.5 {+-} 3.4 days. Vaginal bleeding was fully controlled in 80 patients within 1 to 8 days. The mean {+-} SD follow-up period was 27.6 {+-} 12.7 months (range, 6-48 months). Five patients died due to recurrence or metastasis. The 3-year survival and disease-free recurrence rates were 89.6% and 87.5 %, respectively. Nine patients experienced mild radiation proctitis, and 4 patients developed radiocystitis. Conclusions: Low-dose-rate {sup 252}Cf neutron RT combined with external pelvic RT is effective for treating cervical cancer, with a low incidence of

  18. Chelation and stabilization of berkelium in oxidation state +IV

    Science.gov (United States)

    Deblonde, Gauthier J.-P.; Sturzbecher-Hoehne, Manuel; Rupert, Peter B.; An, Dahlia D.; Illy, Marie-Claire; Ralston, Corie Y.; Brabec, Jiri; de Jong, Wibe A.; Strong, Roland K.; Abergel, Rebecca J.

    2017-09-01

    Berkelium (Bk) has been predicted to be the only transplutonium element able to exhibit both +III and +IV oxidation states in solution, but evidence of a stable oxidized Bk chelate has so far remained elusive. Here we describe the stabilization of the heaviest 4+ ion of the periodic table, under mild aqueous conditions, using a siderophore derivative. The resulting Bk(IV) complex exhibits luminescence via sensitization through an intramolecular antenna effect. This neutral Bk(IV) coordination compound is not sequestered by the protein siderocalin—a mammalian metal transporter—in contrast to the negatively charged species obtained with neighbouring trivalent actinides americium, curium and californium (Cf). The corresponding Cf(III)-ligand-protein ternary adduct was characterized by X-ray diffraction analysis. Combined with theoretical predictions, these data add significant insight to the field of transplutonium chemistry, and may lead to innovative Bk separation and purification processes.

  19. Californium-252 neutron intracavity brachytherapy alone for T1N0 low-lying rectal adenocarcinoma: A definitive anal sphincter-preserving radiotherapy

    Science.gov (United States)

    Xiong, Yanli; Shan, Jinlu; Liu, Jia; Zhao, Kewei; Chen, Shu; Xu, Wenjing; Zhou, Qian; Yang, Mei; Lei, Xin

    2017-01-01

    This study evaluated the 4-year results of 32 patients with T1N0 low-lying rectal adenocarcinoma treated solely with californium-252 (Cf-252) neutron intracavity brachytherapy (ICBT). Patients were solicited into the study from January 2008 to June 2011. All the patients had refused surgery or surgery was contraindicated. The patients were treated with Cf-252 neutron ICBT using a novel 3.5-cm diameter off-axis 4-channel intrarectal applicator designed by the authors. The dose reference point was defined on the mucosa surface, with a total dose of 55–62 Gy-eq/4 f (13–16 Gy-eq/f/wk). All the patients completed the radiotherapy in accordance with our protocol. The rectal lesions regressed completely, and the acute rectal toxicity was mild (≤G2). The 4-year local control, overall survival, disease-free survival, and late complication (≥G2) rates were 96.9%, 90.6%, 87.5% and 15.6%, respectively. No severe late complication (≥G3) occurred. The mean follow-up was 56.1 ± 16.0 months. At the end of last follow-up, 29 patients remained alive. The mean survival time was 82.1 ± 2.7 months. Cf-252 neutron ICBT administered as the sole treatment (without surgery) for patients with T1N0 low-lying rectal adenocarcinoma is effective with acceptable late complications. Our study and method offers a definitive anal sphincter-preserving radiotherapy for T1N0 low-lying rectal adenocarcinoma patients. PMID:28094790

  20. Californium-252 Program Equipment Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Chattin, Fred Rhea [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wilson, Kenton [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ezold, Julie G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-12-01

    To successfully continue the 252Cf production and meet the needs of the customers, a comprehensive evaluation of the Building 7920 processing equipment was requested to identify equipment critical to the operational continuity of the program.

  1. Manganese determination om minerals by activation analysis, using the californium-252 as a neutron source; Determinacao de manganes em minerios, por analise por ativacao, usando californio-252 como fonte de neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Cardoso, Antonio

    1976-07-01

    Neutron Activation Analysis, using a Californium-252 neutron source, has been applied for the determination of manganese in ores such as pyrolusite, rodonite (manganese silicate)' and blending used in dry-batteries The favorable nuclear properties of manganese, such as high thermal neutron cross-section for the reaction {sup 55}Mn (n.gamma){sup 56} Mn, high concentration of manganese in the matrix and short half - life of {sup 56}Mn, are an ideal combination for non-destructive analysis of manganese in ores. Samples and standards of manganese dioxide were irradiated for about 20 minutes, followed by a 4 to 15 minutes decay and counted in a single channel pulse-height discrimination using a NaI(Tl) scintillation detector. Counting time was equal to 10 minutes. The interference of nuclear reactions {sup 56}Fe(n,p){sup 56}Mn and {sup 59} Co (n, {alpha}){sup 56} were studied, as well as problems in connection with neutron shadowing during irradiation, gamma-rays attenuation during counting and influence of granulometry of samples. One sample,was also analysed by wet-chemical method (sodium bismuthate) in order to compare results. As a whole, i t was shown that the analytical method of neutron activation for manganese in ores and blending, is a method simple, rapid and with good precision and accuracy. (author)

  2. Design of a homogeneous subcritical nuclear reactor based on thorium with a source of californium 252; Diseno de un reactor nuclear subcritico homogeneo a base de Torio con una fuente de Californio 252

    Energy Technology Data Exchange (ETDEWEB)

    Delgado H, C. E.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas, Zac. (Mexico); Sajo B, L., E-mail: ce_delgado89@hotmail.com [Universidad Simon Bolivar, Laboratorio de Fisica Nuclear, Apdo. 89000, 1080A Caracas (Venezuela, Bolivarian Republic of)

    2015-10-15

    Full text: One of the energy alternatives to fossil fuels which do not produce greenhouse gases is the nuclear energy. One of the drawbacks of this alternative is the generation of radioactive wastes of long half-life and its relation to the generation of nuclear materials to produce weapons of mass destruction. An option to these drawbacks of nuclear energy is to use Thorium as part of the nuclear fuel which it becomes in U{sup 233} when capturing neutrons, that is a fissile material. In this paper Monte Carlo methods were used to design a homogeneous subcritical reactor based on thorium. As neutron reflector graphite was used. The reactor core is homogeneous and is formed of 70% light water as moderator, 12% of enriched uranium UO{sub 2}(NO{sub 3}){sub 4} and 18% of thorium Th(NO{sub 3}){sub 4} as fuel. To start the nuclear fission chain reaction an isotopic source of californium 252 was used with an intensity of 4.6 x 10{sup 7} s{sup -1}. In the design the value of the effective multiplication factor, whose value turned out k{sub eff} <1 was calculated. Also, the neutron spectra at different distances from the source and the total fluence were calculated, as well as the values of the ambient dose equivalent in the periphery of the reactor. (Author)

  3. Systematic studies of the fundamental chemistry of pyrochlore oxides. An{sub 2}Zr{sub 2}O{sub 7} [An=Pu, Am, Cm, Bk and Cf

    Energy Technology Data Exchange (ETDEWEB)

    Haire, R.G.; Assefa, Z. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Raison, P.E. [Commissariat a l' Energie Atomique, CEA-Cadarache DRN/DEC/SPUA/LACA (France)

    2002-11-01

    Our efforts to pursue the fundamental science of actinide pyrochlore oxides, An{sub 2}Zr{sub 2}O{sub 7}, (An=plutonium through californium), are presented. We have addressed their structural and chemical behavior via X-ray diffraction, Raman spectroscopy and by considering the pseudo-oxidation potentials of the actinides. The structure, fundamental chemistry, ionic radii and the electronic configuration of the specific actinide involved in these oxide systems all have a significant impact on their science. We are also exploring a calculational approach based on valence-bond relationships to assess the position of the oxygen atoms located at the general crystallographic position. The oxygen position is important regarding the chemical behavior and thermal stability of these materials. Also considered is the structural stability of the materials regarding self-irradiation, and with some compounds, their resistance towards oxidation. These aspects will be discussed using a systematic evaluation of the five-actinide systems together with comparable lanthanide systems studied. (author)

  4. Catalytic oxidation using nitrous oxide

    Directory of Open Access Journals (Sweden)

    Juan Carlos Beltran-Prieto

    2017-01-01

    Full Text Available Nitrous oxide is a very inert gas used generally as oxidant as it offers some advantage compared with other oxidants such as O2 but a considerably higher temperature (> 526 °C is often required. For particular cases such as the oxidation of sugar alcohols, especially for the oxidation of primary alcohols to aldehydes, N2O has the advantage over O2 of a higher reaction selectivity. In the present paper we present the modelling of oxidation reaction of sugar alcohols using an oxidizing agent in low concentrations, which is important to suppress subsequent oxidation reactions due to the very low residual concentrations of the oxidizing agent. For orientation experiments we chose nitrous oxide generated by thermal decomposition of ammonium nitrate. Kinetic modeling of the reaction was performed after determination of the differential equations that describe the system under study.

  5. RNA oxidation

    DEFF Research Database (Denmark)

    Kjaer, L. K.; Cejvanovic, V.; Henriken, T.

    2015-01-01

    RNA modification has attracted increasing interest as it is realized that epitranscriptomics is important in disease development. In type 2 diabetes we have suggested that high urinary excretion of 8-oxo-2'-Guanosine (8oxoGuo), as a measure of global RNA oxidation, is associated with poor survival.......9 significant hazard ratio for death compared with the quartile with the lowest 8oxoGuo excretion when adjusted for age, sex, BMI, smoker status, s-HbA1c, urine protein excretion and s-cholesterol. We conclude that it is now established that RNA oxidation is an independent risk factor for death in type 2...... diabetes. In agreement with our previous finding, DNA oxidation did not show any prognostic value. RNA oxidation represents oxidative stress intracellularly, presumably predominantly in the cytosol. The mechanism of RNA oxidation is not clear, but hypothesized to result from mitochondrial dysfunction...

  6. [Nitric oxide].

    Science.gov (United States)

    Rovira, I

    1995-01-01

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

  7. Anodic oxidation

    CERN Document Server

    Ross, Sidney D; Rudd, Eric J; Blomquist, Alfred T; Wasserman, Harry H

    2013-01-01

    Anodic Oxidation covers the application of the concept, principles, and methods of electrochemistry to organic reactions. This book is composed of two parts encompassing 12 chapters that consider the mechanism of anodic oxidation. Part I surveys the theory and methods of electrochemistry as applied to organic reactions. These parts also present the mathematical equations to describe the kinetics of electrode reactions using both polarographic and steady-state conditions. Part II examines the anodic oxidation of organic substrates by the functional group initially attacked. This part particular

  8. Magnesium Oxide

    Science.gov (United States)

    Magnesium is an element your body needs to function normally. Magnesium oxide may be used for different reasons. Some people use it as ... daily depending on which brand is used and what condition you have. Follow the directions on the ...

  9. Oxidation catalyst

    Science.gov (United States)

    Ceyer, Sylvia T.; Lahr, David L.

    2010-11-09

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

  10. Oxidative stress

    Directory of Open Access Journals (Sweden)

    Stevanović Jelka

    2012-01-01

    Full Text Available The unceasing need for oxygen is in contradiction to the fact that it is in fact toxic to mammals. Namely, its monovalent reduction can have as a consequence the production of short-living, chemically very active free radicals and certain non-radical agents (nitrogen-oxide, superoxide-anion-radicals, hydroxyl radicals, peroxyl radicals, singlet oxygen, peroxynitrite, hydrogen peroxide, hypochlorous acid, and others. There is no doubt that they have numerous positive roles, but when their production is stepped up to such an extent that the organism cannot eliminate them with its antioxidants (superoxide-dismutase, glutathione-peroxidase, catalase, transferrin, ceruloplasmin, reduced glutathion, and others, a series of disorders is developed that are jointly called „oxidative stress.“ The reactive oxygen species which characterize oxidative stress are capable of attacking all main classes of biological macromolecules, actually proteins, DNA and RNA molecules, and in particular lipids. The free radicals influence lipid peroxidation in cellular membranes, oxidative damage to DNA and RNA molecules, the development of genetic mutations, fragmentation, and the altered function of various protein molecules. All of this results in the following consequences: disrupted permeability of cellular membranes, disrupted cellular signalization and ion homeostasis, reduced or loss of function of damaged proteins, and similar. That is why the free radicals that are released during oxidative stress are considered pathogenic agents of numerous diseases and ageing. The type of damage that will occur, and when it will take place, depends on the nature of the free radicals, their site of action and their source. [Projekat Ministarstva nauke Republike Srbije, br. 173034, br. 175061 i br. 31085

  11. SINTESIS GRAPHENE OXIDE DAN REDUCED GRAPHENE OXIDE

    OpenAIRE

    Rafitasari, Yeti; Suhendar, Haris; Imani, Nurul; Luciana, Fitri; Radean, Hesti; Santoso, Iman

    2016-01-01

    Graphene oxide (GO) and reduced graphene oxide (rGO) have been synthesized chemically from graphite powder. Graphite powder was oxidized with strong oxidator agent molekul  to get graphite oxide, this process was called by Hummer’s methode. Graphite oxide was dispersed in water with ultasonic vibrator to exfoliated graphite oxide layers, and become graphene oxide. Epoxy group in GO structure was reduced by hydrazine 80 wt% to get rGO. Comparation was done between self synthetic rGO and S...

  12. PREFACE: Semiconducting oxides Semiconducting oxides

    Science.gov (United States)

    Catlow, Richard; Walsh, Aron

    2011-08-01

    Semiconducting oxides are amongst the most widely studied and topical materials in contemporary condensed matter science, with interest being driven both by the fundamental challenges posed by their electronic and magnetic structures and properties, and by the wide range of applications, including those in catalysis and electronic devices. This special section aims to highlight recent developments in the physics of these materials, and to show the link between developing fundamental understanding and key application areas of oxide semiconductors. Several aspects of the physics of this wide and expanding range of materials are explored in this special section. Transparent semiconducting oxides have a growing role in several technologies, but challenges remain in understanding their electronic structure and the physics of charge carriers. A related problem concerns the nature of redox processes and the reactions which interconvert defects and charge carriers—a key issue which may limit the extent to which doping strategies may be used to alter electronic properties. The magnetic structures of the materials pose several challenges, while surface structures and properties are vital in controlling catalytic properties, including photochemical processes. The field profits from and exploits a wide range of contemporary physical techniques—both experimental and theoretical. Indeed, the interplay between experiment and computation is a key aspect of contemporary work. A number of articles describe applications of computational methods whose use, especially in modelling properties of defects in these materials, has a long and successful history. Several papers in this special section relate to work presented at a symposium within the European Materials Research Society (EMRS) meeting held in Warsaw in September 2010, and we are grateful to the EMRS for supporting this symposium. We would also like to thank the editorial staff of Journal of Physics: Condensed Matter for

  13. Automated absolute activation analysis with californium-252 sources

    Energy Technology Data Exchange (ETDEWEB)

    MacMurdo, K.W.; Bowman, W.W.

    1978-09-01

    A 100-mg /sup 252/Cf neutron activation analysis facility is used routinely at the Savannah River Laboratory for multielement analysis of many solid and liquid samples. An absolute analysis technique converts counting data directly to elemental concentration without the use of classical comparative standards and flux monitors. With the totally automated pneumatic sample transfer system, cyclic irradiation-decay-count regimes can be pre-selected for up to 40 samples, and samples can be analyzed with the facility unattended. An automatic data control system starts and stops a high-resolution gamma-ray spectrometer and/or a delayed-neutron detector; the system also stores data and controls output modes. Gamma ray data are reduced by three main programs in the IBM 360/195 computer: the 4096-channel spectrum and pertinent experimental timing, counting, and sample data are stored on magnetic tape; the spectrum is then reduced to a list of significant photopeak energies, integrated areas, and their associated statistical errors; and the third program assigns gamma ray photopeaks to the appropriate neutron activation product(s) by comparing photopeak energies to tabulated gamma ray energies. Photopeak areas are then converted to elemental concentration by using experimental timing and sample data, calculated elemental neutron capture rates, absolute detector efficiencies, and absolute spectroscopic decay data. Calculational procedures have been developed so that fissile material can be analyzed by cyclic neutron activation and delayed-neutron counting procedures. These calculations are based on a 6 half-life group model of delayed neutron emission; calculations include corrections for delayed neutron interference from /sup 17/O. Detection sensitivities of < or = 400 ppB for natural uranium and 8 ppB (< or = 0.5 (nCi/g)) for /sup 239/Pu were demonstrated with 15-g samples at a throughput of up to 140 per day. Over 40 elements can be detected at the sub-ppM level.

  14. Metastable charge-transfer state of californium(iii) compounds.

    Science.gov (United States)

    Liu, Guokui; Cary, Samantha K; Albrecht-Schmitt, Thomas E

    2015-06-28

    Among a series of anomalous physical and chemical properties of Cf(iii) compounds revealed by recent investigations, the present work addresses the characteristics of the optical spectra of An(HDPA)3·H2O (An = Am, Cm, and Cf), especially the broadband photoluminescence from Cf(HDPA)3·H2O induced by ligand-to-metal charge transfer (CT). As a result of strong ion-ligand interactions and the relative ease of reducing Cf(iii) to Cf(ii), a CT transition occurs at low energy (transfer state undergoes radiative and non-radiative relaxations. Broadening of the CT transition arises from strong vibronic coupling and hole-charge interactions in the valence band. The non-radiative relaxation of the metastable CT state results from a competition between phonon-relaxation and thermal tunneling that populates the excited states of Cf(iii).

  15. Nitrogen oxides

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, T.; Horiike, E.; Murakami, M.; Hosoya, T.; Miyanishi, T.; Amamiya, S.

    1975-08-01

    This invention relates to the removal of nitrogen oxides with an aqueous alkaline solution. Waste gas was introduced to an absorbing tower at a flow rate of 0.7--1.0 m/s while sodium hydroxide solution was pumped to the top of the tower at 10--15 l/m/sup 3/ gas. The liquid was sprayed into the waste gas and the resulting gas was led to a second absorbing tower and then a decomposition tower where the remaining NO/sub x/ was removed by sodium sulfide solution or Na/sub 2/S and NaOH mixed solution. With two absorbing towers and one decomposition tower, NO/sub x/ concentration was reduced from 2500 ppM to as low as 36 ppM, or 99 percent removal. With three absorbing towers, the rate of removal was below 80 percent.

  16. Electrochemical oxidation of cholesterol

    Directory of Open Access Journals (Sweden)

    Jacek W. Morzycki

    2015-03-01

    Full Text Available Indirect cholesterol electrochemical oxidation in the presence of various mediators leads to electrophilic addition to the double bond, oxidation at the allylic position, oxidation of the hydroxy group, or functionalization of the side chain. Recent studies have proven that direct electrochemical oxidation of cholesterol is also possible and affords different products depending on the reaction conditions.

  17. Thermally exfoliated graphite oxide

    Science.gov (United States)

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

    2011-01-01

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

  18. Catalytic ammonia oxidation to nitrogen (i) oxide

    OpenAIRE

    MASALITINA NATALIYA YUREVNA; SAVENKOV ANATOLIY SERGEEVICH

    2015-01-01

    The process of synthesis of nitrous oxide by low-temperature catalytical oxidation of NH has been investigated for organic synthesis. The investigation has been carried out by the stage separation approach with NH oxidation occurring in several reaction zones, which characterized by different catalytic conditions. The selectivity for N2O was 92-92,5% at the ammonia conversion of 98-99.5% in the optimal temperature range

  19. The Enzymatic Oxidation of Graphene Oxide

    Science.gov (United States)

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

    2011-01-01

    Two-dimensional graphitic carbon is a new material with many emerging applications, and studying its chemical properties is an important goal. Here, we reported a new phenomenon – the enzymatic oxidation of a single layer of graphitic carbon by horseradish peroxidase (HRP). In the presence of low concentrations of hydrogen peroxide (~40 µM), HRP catalyzed the oxidation of graphene oxide, which resulted in the formation of holes on its basal plane. During the same period of analysis, HRP failed to oxidize chemically reduced graphene oxide (RGO). The enzymatic oxidation was characterized by Raman, UV-Vis, EPR and FT-IR spectroscopy, TEM, AFM, SDS-PAGE, and GC-MS. Computational docking studies indicated that HRP was preferentially bound to the basal plane rather than the edge for both graphene oxide and RGO. Due to the more dynamic nature of HRP on graphene oxide, the heme active site of HRP was in closer proximity to graphene oxide compared to RGO, thereby facilitating the oxidation of the basal plane of graphene oxide. We also studied the electronic properties of the reduced intermediate product, holey reduced graphene oxide (hRGO), using field-effect transistor (FET) measurements. While RGO exhibited a V-shaped transfer characteristic similar to a single layer of graphene that was attributed to its zero band gap, hRGO demonstrated a p-type semiconducting behavior with a positive shift in the Dirac points. This p-type behavior rendered hRGO, which can be conceptualized as interconnected graphene nanoribbons, as a potentially attractive material for FET sensors. PMID:21344859

  20. The enzymatic oxidation of graphene oxide.

    Science.gov (United States)

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

    2011-03-22

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

  1. Expansion Coefficient on Oxides and Oxide Ceramics.

    Science.gov (United States)

    1986-05-01

    Classification) EXPANSION COEFFICIENTS ON OXIDES AND OXIDE CERAMICS 12 PFRSONAL AUTHOR(S) Josephine Covino 13a TYPE OF REPORT 13b TIME COVERED 114 DATE OF REPORT...drastically alter expansion properties of oxides. It has been found that fine-grained (᝺ tm) anisotropic ceramic materials, such as hafnium oxide, hafnium ...Gokhale. "Thermal Expansion of Zircon ," Jap. J. AppZ. Phys., 7 (1968), p. 1126. 34 -- ’-a.’! nw-W’W L. .WW U. .PV _ 77 NWC TP 6663 81. J. L. Amoros, M

  2. Nitric oxide supersensitivity

    DEFF Research Database (Denmark)

    Olesen, J; Iversen, Helle Klingenberg; Thomsen, L L

    1993-01-01

    Nitroglycerin, which may be regarded as a prodrug for nitric oxide, induces a mild to moderate headache in healthy subjects. In order to study whether migraine patients are more sensitive to nitric oxide than non-migrainous subjects, four different doses of intravenous nitroglycerin were given...... previously shown a similar supersensitivity to histamine which in human cerebral arteries activates endothelial H1 receptors and causes endothelial production of nitric oxide. Migraine patients are thus supersensitive to exogenous nitric oxide from nitroglycerin as well as to endothelially produced nitric...... oxide. It is suggested that nitric oxide may be partially or completely responsible for migraine pain....

  3. Oxidative Stress in Neurodegeneration

    Directory of Open Access Journals (Sweden)

    Varsha Shukla

    2011-01-01

    Full Text Available It has been demonstrated that oxidative stress has a ubiquitous role in neurodegenerative diseases. Major source of oxidative stress due to reactive oxygen species (ROS is related to mitochondria as an endogenous source. Although there is ample evidence from tissues of patients with neurodegenerative disorders of morphological, biochemical, and molecular abnormalities in mitochondria, it is still not very clear whether the oxidative stress itself contributes to the onset of neurodegeneration or it is part of the neurodegenerative process as secondary manifestation. This paper begins with an overview of how oxidative stress occurs, discussing various oxidants and antioxidants, and role of oxidative stress in diseases in general. It highlights the role of oxidative stress in neurodegenerative diseases like Alzheimer's, Parkinson's, and Huntington's diseases and amyotrophic lateral sclerosis. The last part of the paper describes the role of oxidative stress causing deregulation of cyclin-dependent kinase 5 (Cdk5 hyperactivity associated with neurodegeneration.

  4. Bridged graphite oxide materials

    Science.gov (United States)

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

    2010-01-01

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

  5. Zinc oxide overdose

    Science.gov (United States)

    Zinc oxide is an ingredient in many products. Some of these are certain creams and ointments used to prevent or treat minor skin burns and irritation. Zinc oxide overdose occurs when someone eats one of these ...

  6. Nitrous Oxide Flux

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Nitrous Oxide (N20) flux is the net rate of nitrous oxide exchange between an ecosystem and the atmosphere. Data of this variable were generated by the USGS...

  7. Oxidation of Alkylaromatics

    Directory of Open Access Journals (Sweden)

    T. S. S. Rao

    2007-01-01

    Full Text Available Hydroperoxide at α-position to the aromatic ring is the primary oxidation product formed. In all cases monoalkylbenzenes lead to the formation of benzoic acid. Oxidation in the presence of transition metal salts not only accelerate but also selectively decompose the hydroperoxides. Alkyl naphthalenes mainly produce the corresponding naphthalene carboxylic acids. Hock-rearrangement by the influence of strong acids converts the hydroperoxides to hemiacetals. Peresters formed from the hydroperoxides undergo Criegee rearrangement easily. Alkali metals accelerate the oxidation while CO2 as co-oxidant enhances the selectivity. Microwave conditions give improved yields of the oxidation products.

  8. Silicon oxidation by ozone

    Energy Technology Data Exchange (ETDEWEB)

    Fink, Christian K; Jenkins, Stephen J [Department of Chemistry, University of Cambridge, Cambridge CB2 1EW (United Kingdom); Nakamura, Ken; Ichimura, Shingo [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)], E-mail: sjj24@cam.ac.uk

    2009-05-06

    Understanding the oxidation of silicon has been an ongoing challenge for many decades. Ozone has recently received considerable attention as an alternative oxidant in the low temperature, damage-free oxidation of silicon. The ozone-grown oxide was also found to exhibit improved interface and electrical characteristics over a conventionally dioxygen-grown oxide. In this review article, we summarize the key findings about this alternative oxidation process. We discuss the different methods of O{sub 3} generation, and the advantages of the ozone-grown Si/SiO{sub 2} interface. An understanding of the growth characteristics is of utmost importance for obtaining control over this alternative oxidation process. (topical review)

  9. Oxidation of Non-Oxide Ceramics.

    Science.gov (United States)

    1982-05-25

    stacking faults Fig. 4. Unoxidized polished surface in cristobalite spherulite formed of sintered beta SiC (SEM) on sintered alpha SiC in 0 at 13000 C (TEn...electron and transmission electron microscopy were used to examine the oxide film. Experiments showed that cristobalite nucleates at the SiC/SiO 2 interface...and also that appreciable heterogeneous nucleation occurs during the first hour of oxidation. The growth rate of cristobalite was determined to be

  10. ZIRCONIUM OXIDE NANOSTRUCTURES PREPARED BY ANODIC OXIDATION

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-01-01

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

  11. Diclofenac oxidation by biogenic manganese oxides.

    Science.gov (United States)

    Forrez, Ilse; Carballa, Marta; Verbeken, Kim; Vanhaecke, Lynn; Ternes, Thomas; Boon, Nico; Verstraete, Willy

    2010-05-01

    Diclofenac, a nonsteroidal anti-inflammatory drug, is one of the most commonly detected pharmaceuticals in sewage treatment plant (STP) effluents. In this work, biologically produced manganese oxides (BioMnOx) were investigated to remove diclofenac. At neutral pH, the diclofenac oxidation with BioMnOx was 10-fold faster than with chemically produced MnO(2). The main advantage of BioMnOx over chemical MnO(2) is the ability of the bacteria to reoxidize the formed Mn(2+), which inhibits the oxidation of diclofenac. Diclofenac-2,5-iminoquinone was identified as a major transformation product, accounting for 5-10% of the transformed diclofenac. Except for 5-hydroxydiclofenac, which was identified as an intermediate, no other oxidation products were detected. Diclofenac oxidation was proportional to the amount of BioMnOx dosed, and the pseudo first order rate constant k was 6-fold higher when pH was decreased from 6.8 to 6.2. The Mn(2+) levels remained below the drinking water limit (0.05 mg L(-1)), thus indicating the efficient in situ microbiological regeneration of the oxidant. These results combined with previous studies suggest the potential of BioMnOx for STP effluent polishing.

  12. Oxidation Resistant Graphite Studies

    Energy Technology Data Exchange (ETDEWEB)

    W. Windes; R. Smith

    2014-07-01

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

  13. Biomimetic Water-Oxidation Catalysts: Manganese Oxides.

    Science.gov (United States)

    Kurz, Philipp

    2016-01-01

    The catalytic oxidation of water to molecular oxygen is a key process for the production of solar fuels. Inspired by the biological manganese-based active site for this reaction in the enzyme Photosystem II, researchers have made impressive progress in the last decades regarding the development of synthetic manganese catalysts for water oxidation. For this, it has been especially fruitful to explore the many different types of known manganese oxides MnOx. This chapter first offers an overview of the structural, thermodynamic, and mechanistic aspects of water-oxidation catalysis by MnOx. The different test systems used for catalytic studies are then presented together with general reactivity trends. As a result, it has been possible to identify layered, mixed Mn (III/IV)-oxides as an especially promising class of bio-inspired catalysts and an attempt is made to give structure-based reasons for the good performances of these materials. In the outlook, the challenges of catalyst screenings (and hence the identification of a "best MnOx catalyst") are discussed. There is a great variety of reaction conditions which might be relevant for the application of manganese oxide catalysts in technological solar fuel-producing devices, and thus catalyst improvements are currently still addressing a very large parameter space. Nonetheless, detailed knowledge about the biological catalyst and a solid experimental basis concerning the syntheses and water-oxidation reactivities of MnOx materials have been established in the last decade and thus this research field is well positioned to make important contributions to solar fuel research in the future.

  14. Oxidizer Scoping Studies

    Energy Technology Data Exchange (ETDEWEB)

    Chancellor, Christopher John [Los Alamos National Laboratory

    2016-11-07

    The purpose of this report is to present the results of the acceptable knowledge (AK) review of oxidizers present in active waste streams, provide a technical analysis of the oxidizers, and report the results of the scoping study testing. This report will determine the fastest burning oxidizer to be used in the development of a Test Plan for Preparation and Testing of Sorbents Mixed with Oxidizer found in Transuranic Waste (DWT-TP-001). The companion report, DWT-RPT-002, Sorbent Scoping Studies, contains similar information for sorbents identified during the AK review of TRU waste streams. The results of the oxidizer and sorbent scoping studies will be used to inform the QL1 test plan. The QL1 test results will support the development of a basis of knowledge document that will evaluate oxidizing chemicals and sorbents in TRU waste and provide guidance for treatment.

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

    Science.gov (United States)

    Lu, Peizhen Kathy; Mahapatra, Manoj Kumar

    2013-09-24

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

  16. Modeling of graphite oxide

    OpenAIRE

    Boukhvalov, D. W.; Katsnelson, M. I.

    2008-01-01

    Based on density functional calculations, optimized structures of graphite oxide are found for various coverage by oxygen and hydroxyl groups, as well as their ratio corresponding to the minimum of total energy. The model proposed describes well known experimental results. In particular, it explains why it is so difficult to reduce the graphite oxide up to pure graphene. Evolution of the electronic structure of graphite oxide with the coverage change is investigated.

  17. METAL OXIDE NANOPARTICLES

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-10-01

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

  18. Molecular water oxidation catalysis

    CERN Document Server

    Llobet, Antoni

    2014-01-01

    Photocatalytic water splitting is a promising strategy for capturing energy from the sun by coupling light harvesting and the oxidation of water, in order to create clean hydrogen fuel. Thus a deep knowledge of the water oxidation catalysis field is essential to be able to come up with useful energy conversion devices based on sunlight and water splitting. Molecular Water Oxidation Catalysis: A Key Topic for New Sustainable Energy Conversion Schemes presents a comprehensive and state-of-the-art overview of water oxidation catalysis in homogeneous phase, describing in detail the most importan

  19. Oxidants and oxidation in the Earth's atmosphere

    Science.gov (United States)

    1995-01-01

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

  20. Catalytic process for formaldehyde oxidation

    Science.gov (United States)

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

    1996-01-01

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

  1. Reducible oxide based catalysts

    Science.gov (United States)

    Thompson, Levi T.; Kim, Chang Hwan; Bej, Shyamal K.

    2010-04-06

    A catalyst is disclosed herein. The catalyst includes a reducible oxide support and at least one noble metal fixed on the reducible oxide support. The noble metal(s) is loaded on the support at a substantially constant temperature and pH.

  2. Markers of protein oxidation

    DEFF Research Database (Denmark)

    Headlam, Henrietta A; Davies, Michael Jonathan

    2004-01-01

    Exposure of proteins to radicals in the presence of O2 gives both side-chain oxidation and backbone fragmentation. These processes can be interrelated, with initial side-chain oxidation giving rise to backbone damage via transfer reactions. We have shown previously that alkoxyl radicals formed on...

  3. Catalyst for Ammonia Oxidation

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a bimetallic catalyst for ammonia oxidation, a method for producing a bimetallic catalyst for ammonia oxidation and a method for tuning the catalytic activity of a transition metal. By depositing an overlayer of less catalytic active metal onto a more catalytic...

  4. studies in oxidation

    Indian Academy of Sciences (India)

    species of valence four or five or possibly, even two. Watanabe and. Westheimer' employed Successfully the induced oxidation of the manganots ion as a diagnostic tool in determining which chromium species is formed in the first step of the oxidation of isopropyl alcohol in aqueous perchloric acid media. The present paper ...

  5. Death from Nitrous Oxide.

    Science.gov (United States)

    Bäckström, Björn; Johansson, Bengt; Eriksson, Anders

    2015-11-01

    Nitrous oxide is an inflammable gas that gives no smell or taste. It has a history of abuse as long as its clinical use, and deaths, although rare, have been reported. We describe two cases of accidental deaths related to voluntary inhalation of nitrous oxide, both found dead with a gas mask covering the face. In an attempt to find an explanation to why the victims did not react properly to oncoming hypoxia, we performed experiments where a test person was allowed to breath in a closed system, with or without nitrous oxide added. Vital signs and gas concentrations as well as subjective symptoms were recorded. The experiments indicated that the explanation to the fact that neither of the descendents had reacted to oncoming hypoxia and hypercapnia was due to the inhalation of nitrous oxide. This study raises the question whether nitrous oxide really should be easily, commercially available. © 2015 American Academy of Forensic Sciences.

  6. RNA modifications by oxidation

    DEFF Research Database (Denmark)

    Poulsen, Henrik E; Specht, Elisabeth; Broedbaek, Kasper

    2012-01-01

    The past decade has provided exciting insights into a novel class of central (small) RNA molecules intimately involved in gene regulation. Only a small percentage of our DNA is translated into proteins by mRNA, yet 80% or more of the DNA is transcribed into RNA, and this RNA has been found...... to encompass various classes of novel regulatory RNAs, including, e.g., microRNAs. It is well known that DNA is constantly oxidized and repaired by complex genome maintenance mechanisms. Analogously, RNA also undergoes significant oxidation, and there are now convincing data suggesting that oxidation......, and the consequent loss of integrity of RNA, is a mechanism for disease development. Oxidized RNA is found in a large variety of diseases, and interest has been especially devoted to degenerative brain diseases such as Alzheimer disease, in which up to 50-70% of specific mRNA molecules are reported oxidized, whereas...

  7. Protein oxidation in aquatic foods

    DEFF Research Database (Denmark)

    Baron, Caroline P.

    2014-01-01

    The chapter discusses general considerations about protein oxidation and reviews the mechanisms involved in protein oxidation and consequences of protein oxidation on fish proteins. It presents two case studies, the first deals with protein and lipid oxidation in frozen rainbow trout......, and the second with oxidation in salted herring. The mechanisms responsible for initiation of protein oxidation are unclear, but it is generally accepted that free radical species initiating lipid oxidation can also initiate protein oxidation. The chapter focuses on interaction between protein and lipid...... oxidation. The protein carbonyl group measurement is the widely used method for estimating protein oxidation in foods and has been used in fish muscle. The chapter also talks about the impact of protein oxidation on protein functionality, fish muscle texture, and food nutritional value. Protein oxidation...

  8. Highly oxidized graphene oxide and methods for production thereof

    Energy Technology Data Exchange (ETDEWEB)

    Tour, James M.; Kosynkin, Dmitry V.

    2016-08-30

    A highly oxidized form of graphene oxide and methods for production thereof are described in various embodiments of the present disclosure. In general, the methods include mixing a graphite source with a solution containing at least one oxidant and at least one protecting agent and then oxidizing the graphite source with the at least one oxidant in the presence of the at least one protecting agent to form the graphene oxide. Graphene oxide synthesized by the presently described methods is of a high structural quality that is more oxidized and maintains a higher proportion of aromatic rings and aromatic domains than does graphene oxide prepared in the absence of at least one protecting agent. Methods for reduction of graphene oxide into chemically converted graphene are also disclosed herein. The chemically converted graphene of the present disclosure is significantly more electrically conductive than is chemically converted graphene prepared from other sources of graphene oxide.

  9. CHEMILUMINESCENCE ON OXIDE SURFACE

    OpenAIRE

    L. I. IVANKIV; O. V. DZYUPYN; Balitskii, O. A.

    2008-01-01

    This paper describes the oxygen adsorption properties on magnesium oxide surface. The results are compared with theoretical adsorption kinetics. Temperature and time dependences of adsorption mechanisms and chemiluminescence are discussed.

  10. High Current Oxide Cathodes

    National Research Council Canada - National Science Library

    Luhmann, N

    2000-01-01

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

  11. Cathodoluminescence of uranium oxides

    Energy Technology Data Exchange (ETDEWEB)

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

    1984-08-09

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

  12. Wet oxidation of quinoline

    DEFF Research Database (Denmark)

    Thomsen, A.B.; Kilen, H.H.

    1998-01-01

    The influence of oxygen pressure (0.4 and 2 MPa). reaction time (30 and 60 min) and temperature (260 and 280 degrees C) on the wet oxidation of quinoline has been studied. The dominant parameters for the decomposition of quinoline were oxygen pressure and reaction temperature. whereas the reaction...... if low oxygen pressure or long reaction times were used. The reaction products derived from the experiment in which quinoline was mostly decomposed were studied with respect to biological degradation. The results showed that these products were highly digestible under activated sludge treatment....... The combined wet oxidation and biological treatment of reaction products resulted in 91% oxidation of the parent compound to CO2 and water. Following combined wet oxidation and biological treatment the sample showed low toxicity towards Nitrosomonas and no toxicity towards Nitrobacter. (C) 1998 Elsevier...

  13. CATALYTIC ENANTIOSELECTIVE ALLYLIC OXIDATION

    NARCIS (Netherlands)

    Rispens, Minze T.; Zondervan, Charon; Feringa, Bernard

    Several chiral Cu(II)-complexes of cyclic amino acids catalyse the enantioselective allylic oxidation of cyclohexene to cyclohexenyl esters. Cyclohexenyl propionate was obtained in 86% yield with e.e.'s up to 61%.

  14. High Current Oxide Cathodes

    National Research Council Canada - National Science Library

    Luhmann, N

    2000-01-01

    .... The vacuum are plasma deposition gun developed at Lawrence Berkeley National Laboratory (LBNL) has been used to deposit oxides and nitrides with very precise control over deposition rate and composition.

  15. Does oxidative stress shorten telomeres?

    NARCIS (Netherlands)

    Boonekamp, Jelle J.; Bauch, Christina; Mulder, Ellis; Verhulst, Simon

    Oxidative stress shortens telomeres in cell culture, but whether oxidative stress explains variation in telomere shortening in vivo at physiological oxidative stress levels is not well known. We therefore tested for correlations between six oxidative stress markers and telomere attrition in nestling

  16. Enargite oxidation: A review

    Science.gov (United States)

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

    2008-01-01

    Enargite, Cu 3AsS 4, is common in some deposit types, e.g. porphyry systems and high sulphidation epithermal deposits. It is of environmental concern as a potential source of arsenic. In this communication, we review the current knowledge of enargite oxidation, based on the existing literature and our own original data. Explicit descriptions of enargite oxidation in natural environments are scarce. The most common oxidized alteration mineral of enargite is probably scorodite, FeAsO 4.2H 2O, with iron provided most likely by pyrite, a phase almost ubiquitously associated with enargite. Other secondary minerals after enargite include arsenates such as chenevixite, Cu 2Fe 2(AsO 4) 2(OH) 4.H 2O, and ceruleite, Cu 2Al 7(AsO 4) 4.11.5H 2O, and sulphates such as brochantite, Cu 4(SO 4)(OH) 6, and posnjakite, Cu 4(SO 4)(OH) 6·H 2O. Detailed studies of enargite field alteration at Furtei, Sardinia, suggest that most alteration occurs through dissolution, as testified by the appearance of etch pits at the surface of enargite crystals. However, apparent replacement by scorodite and cuprian melanterite was observed. Bulk oxidation of enargite in air is a very slow process. However, X-ray photoelectron spectroscopy (XPS) reveals subtle surface changes. From synchrotron-based XPS it was suggested that surface As atoms react very fast, presumably by forming bonds with oxygen. Conventional XPS shows the formation, on aged samples, of a nanometer-size alteration layer with an appreciably distinct composition with respect to the bulk. Mechanical activation considerably increases enargite reactivity. In laboratory experiments at acidic to neutral pH, enargite oxidation/dissolution is slow, although it is accelerated by the presence of ferric iron and/or bacteria such as Acidithiobacillus ferrooxidans and Sulfolobus BC. In the presence of sulphuric acid and ferric iron, the reaction involves dissolution of Cu and formation of native sulphur, subsequently partly oxidized to sulphate

  17. Antibacterial activity of graphite, graphite oxide, graphene oxide, and reduced graphene oxide: membrane and oxidative stress.

    Science.gov (United States)

    Liu, Shaobin; Zeng, Tingying Helen; Hofmann, Mario; Burcombe, Ehdi; Wei, Jun; Jiang, Rongrong; Kong, Jing; Chen, Yuan

    2011-09-27

    Health and environmental impacts of graphene-based materials need to be thoroughly evaluated before their potential applications. Graphene has strong cytotoxicity toward bacteria. To better understand its antimicrobial mechanism, we compared the antibacterial activity of four types of graphene-based materials (graphite (Gt), graphite oxide (GtO), graphene oxide (GO), and reduced graphene oxide (rGO)) toward a bacterial model-Escherichia coli. Under similar concentration and incubation conditions, GO dispersion shows the highest antibacterial activity, sequentially followed by rGO, Gt, and GtO. Scanning electron microscope (SEM) and dynamic light scattering analyses show that GO aggregates have the smallest average size among the four types of materials. SEM images display that the direct contacts with graphene nanosheets disrupt cell membrane. No superoxide anion (O(2)(•-)) induced reactive oxygen species (ROS) production is detected. However, the four types of materials can oxidize glutathione, which serves as redox state mediator in bacteria. Conductive rGO and Gt have higher oxidation capacities than insulating GO and GtO. Results suggest that antimicrobial actions are contributed by both membrane and oxidation stress. We propose that a three-step antimicrobial mechanism, previously used for carbon nanotubes, is applicable to graphene-based materials. It includes initial cell deposition on graphene-based materials, membrane stress caused by direct contact with sharp nanosheets, and the ensuing superoxide anion-independent oxidation. We envision that physicochemical properties of graphene-based materials, such as density of functional groups, size, and conductivity, can be precisely tailored to either reducing their health and environmental risks or increasing their application potentials. © 2011 American Chemical Society

  18. Methanol partial oxidation reformer

    Science.gov (United States)

    Ahmed, Shabbir; Kumar, Romesh; Krumpelt, Michael

    1999-01-01

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

  19. Methanol partial oxidation reformer

    Science.gov (United States)

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

    1999-08-24

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

  20. Nitroalkane Oxidation by Streptomycetes

    Science.gov (United States)

    Dhawale, Motiram R.; Hornemann, Ulfert

    1979-01-01

    Crude cell-free extracts of nine strains of Streptomyces tested for nitroalkane-oxidizing activity showed production of nitrous acid from 2-nitropropane, 1-nitropropane, nitroethane, nitromethane, and 3-nitropropionic acid. These substrates were utilized in most strains but to a decreasing extent in the order given, and different strains varied in their relative efficiency of oxidation. p-Nitrobenzoic acid, p-aminobenzoic acid, enteromycin, and ω-nitro-l-arginine were not attacked. d-Amino acid oxidase, glucose oxidase, glutathione S-transferase, and xanthine oxidase, enzymes potentially responsible for the observed oxidations in crude cellfree extracts, were present at concentrations too low to play any significant role. A nitroalkane-oxidizing enzyme from streptozotocin-producing Streptomyces achromogenes subsp. streptozoticus was partially purified and characterized. It catalyzes the oxidative denitrification of 2-nitropropane as follows: 2CH3CH(NO2)CH3 + O2 → 2CH3COCH3 + 2HNO2. At the optimum pH of 7.5 of the enzyme, 2-nitropropane was as good a substrate as its sodium salt; t-nitrobutane was not a substrate. Whereas Tiron, oxine, and nitroxyl radical acted as potent inhibitors of this enzyme, superoxide dismutase was essentially without effect. Sodium peroxide abolished a lag phase in the progress curve of the enzyme and afforded stimulation, whereas sodium superoxide did not affect the reaction. Reducing agents, such as glutathione, reduced nicotinamide adenine dinucleotide, and nicotinamide adenine dinucleotide phosphate, reduced form, as well as thiol compounds, were strongly inhibitory, but cyanide had no effect. The S. achromogenes enzyme at the present stage of purification is similar in many respects to the enzyme 2-nitropropane dioxygenase from Hansenula mrakii. The possible involvement of the nitroalkane-oxidizing enzyme in the biosynthesis of antibiotics that contain a nitrogen-nitrogen bond is discussed. PMID:33965

  1. Protein oxidation and ageing

    DEFF Research Database (Denmark)

    Linton, S; Davies, Michael Jonathan; Dean, R T

    2001-01-01

    of redox-active metal ions that could catalyse oxidant formation. As a result of this decrease in antioxidant defences, and increased rate of ROS formation, it is possible that the impact of ROS increases with age. ROS are known to oxidise biological macromolecules, with proteins an important target...

  2. Dopamine Oxidation and Autophagy

    Directory of Open Access Journals (Sweden)

    Patricia Muñoz

    2012-01-01

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

  3. Doped zinc oxide microspheres

    Science.gov (United States)

    Arnold, Jr., Wesley D.; Bond, Walter D.; Lauf, Robert J.

    1993-01-01

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

  4. Oxidative Stress in Myopia

    Science.gov (United States)

    Francisco, Bosch-Morell; Salvador, Mérida; Amparo, Navea

    2015-01-01

    Myopia affected approximately 1.6 billion people worldwide in 2000, and it is expected to increase to 2.5 billion by 2020. Although optical problems can be corrected by optics or surgical procedures, normal myopia and high myopia are still an unsolved medical problem. They frequently predispose people who have them to suffer from other eye pathologies: retinal detachment, glaucoma, macular hemorrhage, cataracts, and so on being one of the main causes of visual deterioration and blindness. Genetic and environmental factors have been associated with myopia. Nevertheless, lack of knowledge in the underlying physiopathological molecular mechanisms has not permitted an adequate diagnosis, prevention, or treatment to be found. Nowadays several pieces of evidence indicate that oxidative stress may help explain the altered regulatory pathways in myopia and the appearance of associated eye diseases. On the one hand, oxidative damage associated with hypoxia myopic can alter the neuromodulation that nitric oxide and dopamine have in eye growth. On the other hand, radical superoxide or peroxynitrite production damage retina, vitreous, lens, and so on contributing to the appearance of retinopathies, retinal detachment, cataracts and so on. The objective of this review is to suggest that oxidative stress is one of the key pieces that can help solve this complex eye problem. PMID:25922643

  5. Solid Oxide Fuel Cell

    DEFF Research Database (Denmark)

    2010-01-01

    The solid oxide fuel cell comprising a metallic support material, an active anode layer consisting of a good hydrocarbon cracking catalyst, an electrolyte layer, an active cathode layer, and a transition layer consisting of preferably a mixture of LSM and a ferrite to the cathode current collector...

  6. Partial Oxidation of n-Pentane over Vanadium Phosphorus Oxide ...

    African Journals Online (AJOL)

    The selective oxidation of n-pentane to value-added products, maleic anhydride or phthallic anhydride by vanadium phosphorus oxide loaded on hydroxyapatites as catalysts and oxygen as oxidant was investigated. Hydroxyapatite (HAp) and cobalthydroxyapatite (Co-HAp) were prepared by the co-precipitation method ...

  7. Nanostructured transition metal oxides useful for water oxidation catalysis

    Science.gov (United States)

    Frei, Heinz M; Jiao, Feng

    2013-12-24

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

  8. Trends for Methane Oxidation at Solid Oxide Fuel Cell Conditions

    DEFF Research Database (Denmark)

    Kleis, Jesper; Jones, Glenn; Abild-Pedersen, Frank

    2009-01-01

    First-principles calculations are used to predict a plausible reaction pathway for the methane oxidation reaction. In turn, this pathway is used to obtain trends in methane oxidation activity at solid oxide fuel cell (SOFC) anode materials. Reaction energetics and barriers for the elementary...

  9. Nitrous Oxide Micro Engines Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Nitrous Oxide Micro Engines (NOME) are a new type of nitrous oxide dissociation thruster designed to generate low levels of thrust that can be used for RCS control...

  10. Staged membrane oxidation reactor system

    Science.gov (United States)

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

    2013-04-16

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

  11. Thin film metal-oxides

    CERN Document Server

    Ramanathan, Shriram

    2009-01-01

    Presents an account of the fundamental structure-property relations in oxide thin films. This title discusses the functional properties of thin film oxides in the context of applications in the electronics and renewable energy technologies.

  12. Oxidants and antioxidants in disease

    DEFF Research Database (Denmark)

    Lykkesfeldt, Jens; Svendsen, Ove

    2007-01-01

    Important infectious diseases in farm animals, such as pneumonia and enteritis, are thought to be associated with the so-called oxidative stress, i.e. a chemical phenomenon involving an imbalance in the redox status of the individual animal. The specifics of oxidative stress and how it may result...... theoretically, oxidative stress should be easily prevented with antioxidants yet the use of antioxidants as therapy remains controversial. The present knowledge on oxidative stress in farm animals is the topic of this review....

  13. Oxidative stress in Alzheimer disease

    OpenAIRE

    Gella, Alejandro; Durany, Nuria

    2009-01-01

    Alzheimer disease (AD) is a progressive dementia affecting a large proportion of the aging population. The histopathological changes in AD include neuronal cell death, formation of amyloid plaques and neurofibrillary tangles. There is also evidence that brain tissue in patients with AD is exposed to oxidative stress (e.g., protein oxidation, lipid oxidation, DNA oxidation and glycoxidation) during the course of the disease. Advanced glycation endproducts (AGEs) are present in amyloid plaques ...

  14. Low Temperature Oxidation of Methane: The Influence of Nitrogen Oxides

    DEFF Research Database (Denmark)

    Bendtsen, Anders Broe; Glarborg, Peter; Dam-Johansen, Kim

    2000-01-01

    An experimental investigation of methane oxidation in the presence of NO and NO2 has been made in an isothermal plug-flow reactor at 750-1250K. The temperature for on-set of oxidation was lowered by 250 K in the presence of NO or NO2 at residence times of 200 ms. At shorter residence times (140 ms......) this enhancement effect is reduced for NO but maintained for NO2. Furthermore two temperature regimes of oxidation separated by an intermediate regime where only little oxidation takes place exist at residence times of 140 ms, if NO is the only nitrogen oxide initially present. The results were explained...

  15. Self-assembled manganese oxide structures through direct oxidation

    KAUST Repository

    Zhao, Chao

    2012-12-01

    The morphology and phase of self-assembled manganese oxides during different stages of thermal oxidation were studied. Very interesting morphological patterns of Mn oxide films were observed. At the initial oxidation stage, the surface was characterized by the formation of ring-shaped patterns. As the oxidation proceeded to the intermediate stage, concentric plates formed to relax the compressive stress. Our experimental results gave a clear picture of the evolution of the structures. We also examined the properties of the structures. © 2012 Elsevier B.V.

  16. Oxidative Decarboxylation of Levulinic Acid by Cupric Oxides

    Directory of Open Access Journals (Sweden)

    Lu Lin

    2010-11-01

    Full Text Available In this paper, cupric oxides was found to effectively oxidize levulinic acid (LA and lead to the decarboxylation of levulinic acid to 2-butanone. The effects of cupric oxide dosage, reaction time and initial pH value were investigated in batch experiments and a plausible mechanism was proposed. The results showed that LA decarboxylation over cupric oxides at around 300 °C under acidic conditions produced the highest yield of butanone (67.5%. In order to elucidate the catalytic activity of cupric oxides, XRD, AFM, XPS and H2-TPR techniques was applied to examine their molecular surfaces and their effects on the reaction process.

  17. TEMPO-Oxidized Cellulose with High Degree of Oxidation

    OpenAIRE

    Zuwu Tang; Wenyan Li; Xinxing Lin; He Xiao; Qingxian Miao; Liulian Huang; Lihui Chen; Hui Wu

    2017-01-01

    In this paper, water-soluble 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose with a high degree of oxidation was prepared by a two-step process using bamboo dissolving pulp. The first step was to destroy the cellulose crystal I by NaOH/urea solution to obtain cellulose powder with decreased crystallinity. The second step was to oxidize the cellulose powder by TEMPO oxidation. The TEMPO-oxidized cellulose was analyzed by Fourier transform infrared spectroscopy (FTIR), conductim...

  18. (VI) oxide in acetic acid

    African Journals Online (AJOL)

    The oxidation of cyclohexene by chromium (VI) oxide in aqueous and acetic media was studied. The reaction products were analysed using infra red (IR) and gas chromatography coupled with mass (GC/MS) spectroscopy. The major products of the oxidation reaction in acetic acid medium were cyclohexanol, ...

  19. Manganese oxidation by Leptothrix discophora

    NARCIS (Netherlands)

    Boogerd, F C; de Vrind, J P

    Cells of Leptothrix discophora SS1 released Mn2+-oxidizing factors into the medium during growth in batch culture. Manganese was optimally oxidized when the medium was buffered with HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid) at pH 7.5. Manganese-oxidizing activity in the culture

  20. The aqueous chemistry of oxides

    CERN Document Server

    Bunker, Bruce C

    2016-01-01

    The Aqueous Chemistry of Oxides is a comprehensive reference volume and special topics textbook that explores all of the major chemical reactions that take place between oxides and aqueous solutions. The book highlights the enormous impact that oxide-water reactions have in advanced technologies, materials science, geochemistry, and environmental science.

  1. Model catalytic oxidation studies using supported monometallic and heterobimetallic oxides

    Energy Technology Data Exchange (ETDEWEB)

    Ekerdt, J.G.

    1992-02-03

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

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    After oxidative stress proteins which are oxidatively modified are degraded by the 20S proteasome. However, several studies documented an enhanced ubiquitination of yet unknown proteins. Since ubiqutination is a prerequisite for degradation by the 26S proteasome in an ATP-dependent manner...... this raises the question whether these proteins are also oxidized and, if not, what proteins need to be ubiquitinated and degraded after oxidative conditions. By determination of oxidized- and ubiquitinated proteins we demonstrate here that most oxidized proteins are not preferentially ubiquitinated. However......, we were able to confirm an increase of ubiquitinated proteins 16h upon oxidative stress. Therefore, we isolated ubiquitinated proteins from hydrogen peroxide treated cells, as well as from control and lactacystin, an irreversible proteasome inhibitor, treated cells, and identified some...

  3. TEMPO-Oxidized Cellulose with High Degree of Oxidation

    Directory of Open Access Journals (Sweden)

    Zuwu Tang

    2017-09-01

    Full Text Available In this paper, water-soluble 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO-oxidized cellulose with a high degree of oxidation was prepared by a two-step process using bamboo dissolving pulp. The first step was to destroy the cellulose crystal I by NaOH/urea solution to obtain cellulose powder with decreased crystallinity. The second step was to oxidize the cellulose powder by TEMPO oxidation. The TEMPO-oxidized cellulose was analyzed by Fourier transform infrared spectroscopy (FTIR, conductimetry, X-ray diffraction (XRD, fiber analyzer, and transmission electron microscopy (TEM. FTIR showed that the hydroxymethyl groups in cellulose chains were converted into carboxyl groups. The degree of oxidation measured by conductimetry titration was as high as 91.0%. The TEMPO-oxidized cellulose was soluble in water for valuable polyelectrolytes and intermediates.

  4. Iron oxide surfaces

    Science.gov (United States)

    Parkinson, Gareth S.

    2016-03-01

    The current status of knowledge regarding the surfaces of the iron oxides, magnetite (Fe3O4), maghemite (γ-Fe2O3), haematite (α-Fe2O3), and wüstite (Fe1-xO) is reviewed. The paper starts with a summary of applications where iron oxide surfaces play a major role, including corrosion, catalysis, spintronics, magnetic nanoparticles (MNPs), biomedicine, photoelectrochemical water splitting and groundwater remediation. The bulk structure and properties are then briefly presented; each compound is based on a close-packed anion lattice, with a different distribution and oxidation state of the Fe cations in interstitial sites. The bulk defect chemistry is dominated by cation vacancies and interstitials (not oxygen vacancies) and this provides the context to understand iron oxide surfaces, which represent the front line in reduction and oxidation processes. Fe diffuses in and out from the bulk in response to the O2 chemical potential, forming sometimes complex intermediate phases at the surface. For example, α-Fe2O3 adopts Fe3O4-like surfaces in reducing conditions, and Fe3O4 adopts Fe1-xO-like structures in further reducing conditions still. It is argued that known bulk defect structures are an excellent starting point in building models for iron oxide surfaces. The atomic-scale structure of the low-index surfaces of iron oxides is the major focus of this review. Fe3O4 is the most studied iron oxide in surface science, primarily because its stability range corresponds nicely to the ultra-high vacuum environment. It is also an electrical conductor, which makes it straightforward to study with the most commonly used surface science methods such as photoemission spectroscopies (XPS, UPS) and scanning tunneling microscopy (STM). The impact of the surfaces on the measurement of bulk properties such as magnetism, the Verwey transition and the (predicted) half-metallicity is discussed. The best understood iron oxide surface at present is probably Fe3O4(100); the structure is

  5. Manganese Oxidation by Bacteria: Biogeochemical Aspects

    Digital Repository Service at National Institute of Oceanography (India)

    Sujith, P.P.; LokaBharathi, P.A

    Manganese is an essential trace metal that is not as readily oxidizable like iron. Several bacterial groups posses the ability to oxidize Mn effectively competing with chemical oxidation. The oxides of Mn are the strongest of the oxidants, next...

  6. Enzymatic Oxidation of Methane

    Energy Technology Data Exchange (ETDEWEB)

    Sirajuddin, S; Rosenzweig, AC

    2015-04-14

    Methane monooxygenases (MMOs) are enzymes that catalyze the oxidation of methane to methanol in methanotrophic bacteria. As potential targets for new gas-to-liquid methane bioconversion processes, MMOs have attracted intense attention in recent years. There are two distinct types of MMO, a soluble, cytoplasmic MMO (sMMO) and a membrane-bound, particulate MMO (pMMO). Both oxidize methane at metal centers within a complex, multisubunit scaffold, but the structures, active sites, and chemical mechanisms are completely different. This Current Topic review article focuses on the overall architectures, active site structures, substrate reactivities, proteinprotein interactions, and chemical mechanisms of both MMOs, with an emphasis on fundamental aspects. In addition, recent advances, including new details of interactions between the sMMO components, characterization of sMMO intermediates, and progress toward understanding the pMMO metal centers are highlighted. The work summarized here provides a guide for those interested in exploiting MMOs for biotechnological applications.

  7. Oxidative destruction of chlorocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, P.; Stern, E.W.; Amundsen, A.R.; Balko, E. (Engelhard Corporation, Iselin, NJ (USA))

    1993-02-01

    Presently, there is great concern about contamination of the environment by hazardous volatile organics originating in the manufacture of organic chemicals, cleaning and degreasing processes, and vent or exhaust air from air stripping of contaminated groundwater or soil. Catalytic oxidation is an energy efficient and economical way of destroying such hazardous materials and, depending on overall stream composition and concentration, can compete effectively with alternatives such as thermal incineration and carbon adsorption. This paper discusses the performance of a new catalyst, VOCat 350 HC[trademark], and give a comparison between the VOCat 350 HC[trademark] and the platinum and chromia-alumina catalysts. VOCat 350 HC[trademark] shows excellent activity for oxidation chlorocarbons and good stability in this application. 3 refs., 4 figs.

  8. Defects at oxide surfaces

    CERN Document Server

    Thornton, Geoff

    2015-01-01

    This book presents the basics and characterization of defects at oxide surfaces. It provides a state-of-the-art review of the field, containing information to the various types of surface defects, describes analytical methods to study defects, their chemical activity and the catalytic reactivity of oxides. Numerical simulations of defective structures complete the picture developed. Defects on planar surfaces form the focus of much of the book, although the investigation of powder samples also form an important part. The experimental study of planar surfaces opens the possibility of applying the large armoury of techniques that have been developed over the last half-century to study surfaces in ultra-high vacuum. This enables the acquisition of atomic level data under well-controlled conditions, providing a stringent test of theoretical methods. The latter can then be more reliably applied to systems such as nanoparticles for which accurate methods of characterization of structure and electronic properties ha...

  9. Thin Solid Oxide Cell

    DEFF Research Database (Denmark)

    2010-01-01

    The present invention relates to a thin and in principle unsupported solid oxide cell, comprising at least a porous anode layer, an electrolyte layer and a porous cathode layer, wherein the anode layer and the cathode layer comprise an electrolyte material, at least one metal and a catalyst...... material, and wherein the overall thickness of the thin reversible cell is about 150 [mu]m or less, and to a method for producing same. The present invention also relates to a thin and in principle unsupported solid oxide cell, comprising at least a porous anode layer, an electrolyte layer and a porous...... cathode layer, wherein the anode layer and the cathode layer comprise an electrolyte material and a catalyst material, wherein the electrolyte material is doper zirconia, and wherein the overall thickness of the thin reversible cell is about 150 [mu]m or less, and to a method for producing same...

  10. Entropy-Stabilized Oxides

    Science.gov (United States)

    2015-09-29

    predictions4. There are, however, limitations to the predictive power, particularly when factors like partial covalency and heterodesmic bonding are...broad classes of chalcogenides, nitrides and halides; particularly when covalent character is modest. The entropic driving force—engineered by cation...ultimately manifests in image drift. To do so, E1 films were coated with 50 nm of indium tin oxide (ITO) at room temperature using radio frequency

  11. Infrared transparent conductive oxides

    Science.gov (United States)

    Johnson, Linda F.; Moran, Mark B.

    2001-09-01

    A novel class of complex metal oxides that have potential as transparent conducting oxides (TCOs) for the electromagnetic-interference (EMI) shielding on IR-seeker windows and missile domes has been identified. These complex metal oxides exhibit the rhombohedral (R3m) crystalline structure of naturally occurring delafossite, CuFeO2. The general chemical formula is ABO2 where A is a monovalent metal (Me+1 such as Cu, Ag, Au, Pt or Pd, and B is a trivalent metal (Me3+) such as Al,Ti,Cr,Co,Fe,Ni,Cs,Rh,Ga,Sn,In,Y,La,Pr,Nd,Sm or Eu. By adjusting the oxygen content, the conductivity can be varied over a wide range so that the delafossites behave as insulators, semiconductors or metals. This paper presents results for films of p-type CuxAlyOz and n-type CuxCryOz deposited by reactive magnetron co-sputtering from high-purity-metal targets. Films have been deposited using conventional RF- and DC-power supplies, and a new asymmetric-bipolar-pulsed- DC-power supply. Similar to the high-temperature-copper- oxide superconductors, the presence of Cu-O bonds is critical for the unique properties. Fourier transform infrared (FTIR) and electron spectroscopy for chemical analysis (ESCA) are used to understand the relationship between the optoelectornic properties and the molecular structure of the films. For example, FTIR absorption bands at 1470 and 1395cm-1 are present only in CuxAlyOz films that exhibit enhanced electrical conductivity. When these bands are absent, the CuxAlyOz films have high values of resistivity. In addition to the 1470 and 1395cm-1 bands observed in CuxAlyOz films, another pair of bands at 1040 and 970cm-1 is present in CuxCryOz films.

  12. Antifungal Effect of Magnesium Oxide, Zinc Oxide, Silicon Oxide and Copper Oxide Nanoparticles Against Candida albicans

    OpenAIRE

    Abbas Karimiyan; Hossein Najafzadeh; Masoud Ghorbanpour; Seyed Hossein Hekmati-Moghaddam

    2015-01-01

    Absrtact Background: Candidiasis is the most common fungal infection in human and warm-blooded animals. Candida albicans, is an opportunistic pathogen in immune suppressed hosts, like HIV infected and under chemotherapy patients. Since, antifungal drugs are limited and challenged by resistance. Thus discovering agents with antifungal properties and minimum side effects and toxicity is essential. Nano-agents such as metal oxide nano-particles have unique properties such as high surface to v...

  13. Hysteresis-free high rate reactive sputtering of niobium oxide, tantalum oxide, and aluminum oxide

    Energy Technology Data Exchange (ETDEWEB)

    Särhammar, Erik, E-mail: erik.sarhammar@angstrom.uu.se; Berg, Sören; Nyberg, Tomas [Department of Solid State Electronics, The Ångström Laboratory, Uppsala University, Box 534, SE-751 21 Uppsala (Sweden)

    2014-07-01

    This work reports on experimental studies of reactive sputtering from targets consisting of a metal and its oxide. The composition of the targets varied from pure metal to pure oxide of Al, Ta, and Nb. This combines features from both the metal target and oxide target in reactive sputtering. If a certain relation between the metal and oxide parts is chosen, it may be possible to obtain a high deposition rate, due to the metal part, and a hysteresis-free process, due to the oxide part. The aim of this work is to quantify the achievable boost in oxide deposition rate from a hysteresis-free process by using a target consisting of segments of a metal and its oxide. Such an increase has been previously demonstrated for Ti using a homogeneous substoichiometric target. The achievable gain in deposition rate depends on transformation mechanisms from oxide to suboxides due to preferential sputtering of oxygen. Such mechanisms are different for different materials and the achievable gain is therefore material dependent. For the investigated materials, the authors have demonstrated oxide deposition rates that are 1.5–10 times higher than what is possible from metal targets in compound mode. However, although the principle is demonstrated for oxides of Al, Ta, and Nb, a similar behavior is expected for most oxides.

  14. The 2016 oxide electronic materials and oxide interfaces roadmap

    DEFF Research Database (Denmark)

    Lorenz, M.; Rao, M. S. Ramachandra; Venkatesan, T.

    2016-01-01

    Oxide electronic materials provide a plethora of possible applications and offer ample opportunity for scientists to probe into some of the exciting and intriguing phenomena exhibited by oxide systems and oxide interfaces. In addition to the already diverse spectrum of properties, the nanoscale...... form of oxides provides a new dimension of hitherto unknown phenomena due to the increased surface-to-volume ratio. Oxide electronic materials are becoming increasingly important in a wide range of applications including transparent electronics, optoelectronics, magnetoelectronics, photonics...... of these materials to understand the tunability of their properties and the novel properties that evolve due to their nanostructured nature is another facet of the challenge. The research related to the oxide electronic field is at an impressionable stage, and this has motivated us to contribute with a roadmap...

  15. The oxidative hypothesis of senescence

    Directory of Open Access Journals (Sweden)

    Gilca M

    2007-01-01

    Full Text Available The oxidative hypothesis of senescence, since its origin in 1956, has garnered significant evidence and growing support among scientists for the notion that free radicals play an important role in ageing, either as "damaging" molecules or as signaling molecules. Age-increasing oxidative injuries induced by free radicals, higher susceptibility to oxidative stress in short-lived organisms, genetic manipulations that alter both oxidative resistance and longevity and the anti-ageing effect of caloric restriction and intermittent fasting are a few examples of accepted scientific facts that support the oxidative theory of senescence. Though not completely understood due to the complex "network" of redox regulatory systems, the implication of oxidative stress in the ageing process is now well documented. Moreover, it is compatible with other current ageing theories (e.g., those implicating the mitochondrial damage/mitochondrial-lysosomal axis, stress-induced premature senescence, biological "garbage" accumulation, etc. This review is intended to summarize and critically discuss the redox mechanisms involved during the ageing process: sources of oxidant agents in ageing (mitochondrial -electron transport chain, nitric oxide synthase reaction- and non-mitochondrial- Fenton reaction, microsomal cytochrome P450 enzymes, peroxisomal β -oxidation and respiratory burst of phagocytic cells, antioxidant changes in ageing (enzymatic- superoxide dismutase, glutathione-reductase, glutathion peroxidase, catalase- and non-enzymatic glutathione, ascorbate, urate, bilirubine, melatonin, tocopherols, carotenoids, ubiquinol, alteration of oxidative damage repairing mechanisms and the role of free radicals as signaling molecules in ageing.

  16. The 2016 oxide electronic materials and oxide interfaces roadmap

    Science.gov (United States)

    Lorenz, M.; Ramachandra Rao, M. S.; Venkatesan, T.; Fortunato, E.; Barquinha, P.; Branquinho, R.; Salgueiro, D.; Martins, R.; Carlos, E.; Liu, A.; Shan, F. K.; Grundmann, M.; Boschker, H.; Mukherjee, J.; Priyadarshini, M.; DasGupta, N.; Rogers, D. J.; Teherani, F. H.; Sandana, E. V.; Bove, P.; Rietwyk, K.; Zaban, A.; Veziridis, A.; Weidenkaff, A.; Muralidhar, M.; Murakami, M.; Abel, S.; Fompeyrine, J.; Zuniga-Perez, J.; Ramesh, R.; Spaldin, N. A.; Ostanin, S.; Borisov, V.; Mertig, I.; Lazenka, V.; Srinivasan, G.; Prellier, W.; Uchida, M.; Kawasaki, M.; Pentcheva, R.; Gegenwart, P.; Miletto Granozio, F.; Fontcuberta, J.; Pryds, N.

    2016-11-01

    Oxide electronic materials provide a plethora of possible applications and offer ample opportunity for scientists to probe into some of the exciting and intriguing phenomena exhibited by oxide systems and oxide interfaces. In addition to the already diverse spectrum of properties, the nanoscale form of oxides provides a new dimension of hitherto unknown phenomena due to the increased surface-to-volume ratio. Oxide electronic materials are becoming increasingly important in a wide range of applications including transparent electronics, optoelectronics, magnetoelectronics, photonics, spintronics, thermoelectrics, piezoelectrics, power harvesting, hydrogen storage and environmental waste management. Synthesis and fabrication of these materials, as well as processing into particular device structures to suit a specific application is still a challenge. Further, characterization of these materials to understand the tunability of their properties and the novel properties that evolve due to their nanostructured nature is another facet of the challenge. The research related to the oxide electronic field is at an impressionable stage, and this has motivated us to contribute with a roadmap on ‘oxide electronic materials and oxide interfaces’. This roadmap envisages the potential applications of oxide materials in cutting edge technologies and focuses on the necessary advances required to implement these materials, including both conventional and novel techniques for the synthesis, characterization, processing and fabrication of nanostructured oxides and oxide-based devices. The contents of this roadmap will highlight the functional and correlated properties of oxides in bulk, nano, thin film, multilayer and heterostructure forms, as well as the theoretical considerations behind both present and future applications in many technologically important areas as pointed out by Venkatesan. The contributions in this roadmap span several thematic groups which are represented by

  17. Solid oxide fuel cells fueled with reducible oxides

    Energy Technology Data Exchange (ETDEWEB)

    Chuang, Steven S.; Fan, Liang Shih

    2018-01-09

    A direct-electrochemical-oxidation fuel cell for generating electrical energy includes a cathode provided with an electrochemical-reduction catalyst that promotes formation of oxygen ions from an oxygen-containing source at the cathode, a solid-state reduced metal, a solid-state anode provided with an electrochemical-oxidation catalyst that promotes direct electrochemical oxidation of the solid-state reduced metal in the presence of the oxygen ions to produce electrical energy, and an electrolyte disposed to transmit the oxygen ions from the cathode to the solid-state anode. A method of operating a solid oxide fuel cell includes providing a direct-electrochemical-oxidation fuel cell comprising a solid-state reduced metal, oxidizing the solid-state reduced metal in the presence of oxygen ions through direct-electrochemical-oxidation to obtain a solid-state reducible metal oxide, and reducing the solid-state reducible metal oxide to obtain the solid-state reduced metal.

  18. Ultra supercritical steamside oxidation

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-01-01

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

  19. Semiconducting transition metal oxides

    Science.gov (United States)

    Lany, Stephan

    2015-07-01

    Open shell transition metal oxides are usually described as Mott or charge transfer insulators, which are often viewed as being disparate from semiconductors. Based on the premise that the presence of a correlated gap and semiconductivity are not mutually exclusive, this work reviews electronic structure calculations on the binary 3d oxides, so to distill trends and design principles for semiconducting transition metal oxides. This class of materials possesses the potential for discovery, design, and development of novel functional semiconducting compounds, e.g. for energy applications. In order to place the 3d orbitals and the sp bands into an integrated picture, band structure calculations should treat both contributions on the same footing and, at the same time, account fully for electron correlation in the 3d shell. Fundamentally, this is a rather daunting task for electronic structure calculations, but quasi-particle energy calculations in GW approximation offer a viable approach for band structure predictions in these materials. Compared to conventional semiconductors, the inherent multivalent nature of transition metal cations is more likely to cause undesirable localization of electron or hole carriers. Therefore, a quantitative prediction of the carrier self-trapping energy is essential for the assessing the semiconducting properties and to determine whether the transport mechanism is a band-like large-polaron conduction or a small-polaron hopping conduction. An overview is given for the binary 3d oxides on how the hybridization between the 3d crystal field symmetries with the O-p orbitals of the ligands affects the effective masses and the likelihood of electron and hole self-trapping, identifying those situations where small masses and band-like conduction are more likely to be expected. The review concludes with an illustration of the implications of the increased electronic complexity of transition metal cations on the defect physics and doping, using

  20. Protein oxidation and peroxidation

    DEFF Research Database (Denmark)

    Davies, Michael Jonathan

    2016-01-01

    and chain reactions with alcohols and carbonyls as major products; the latter are commonly used markers of protein damage. Direct oxidation of cysteine (and less commonly) methionine residues is a major reaction; this is typically faster than with H2O2, and results in altered protein activity and function....... Unlike H2O2, which is rapidly removed by protective enzymes, protein peroxides are only slowly removed, and catabolism is a major fate. Although turnover of modified proteins by proteasomal and lysosomal enzymes, and other proteases (e.g. mitochondrial Lon), can be efficient, protein hydroperoxides...

  1. Sulfur Oxides Control Burner.

    Science.gov (United States)

    1983-01-01

    calcium oxide (CaO). Dolomite is a mixture of calcium and magnesium carbonates (CaCO-3 .!gCO ). Neither lime nor limestone react well with SO2 at ambient...temperaturel. At high temperatures (1500*F - 1800*F), both CaCO and CaO appear to react with SO2 . At these temperatures, CaCO is radily calcinated to...process development has been placed on naturally occurring materials, such as limestone and dolomite . APPROACH This investigation evolved from prior

  2. Actinide oxide photodiode and nuclear battery

    Energy Technology Data Exchange (ETDEWEB)

    Sykora, Milan; Usov, Igor

    2017-12-05

    Photodiodes and nuclear batteries may utilize actinide oxides, such a uranium oxide. An actinide oxide photodiode may include a first actinide oxide layer and a second actinide oxide layer deposited on the first actinide oxide layer. The first actinide oxide layer may be n-doped or p-doped. The second actinide oxide layer may be p-doped when the first actinide oxide layer is n-doped, and the second actinide oxide layer may be n-doped when the first actinide oxide layer is p-doped. The first actinide oxide layer and the second actinide oxide layer may form a p/n junction therebetween. Photodiodes including actinide oxides are better light absorbers, can be used in thinner films, and are more thermally stable than silicon, germanium, and gallium arsenide.

  3. Sputtered tin oxide and titanium oxide thin films as alternative transparent conductive oxides

    Energy Technology Data Exchange (ETDEWEB)

    Boltz, Janika

    2011-12-12

    Alternative transparent conductive oxides to tin doped indium oxide have been investigated. In this work, antimony doped tin oxide and niobium doped titanium oxide have been studied with the aim to prepare transparent and conductive films. Antimony doped tin oxide and niobium doped titanium oxide belong to different groups of oxides; tin oxide is a soft oxide, while titanium oxide is a hard oxide. Both oxides are isolating materials, in case the stoichiometry is SnO{sub 2} and TiO{sub 2}. In order to achieve transparent and conductive films free carriers have to be generated by oxygen vacancies, by metal ions at interstitial positions in the crystal lattice or by cation doping with Sb or Nb, respectively. Antimony doped tin oxide and niobium doped titanium oxide films have been prepared by reactive direct current magnetron sputtering (dc MS) from metallic targets. The process parameters and the doping concentration in the films have been varied. The films have been electrically, optically and structurally analysed in order to analyse the influence of the process parameters and the doping concentration on the film properties. Post-deposition treatments of the films have been performed in order to improve the film properties. For the deposition of transparent and conductive tin oxide, the dominant parameter during the deposition is the oxygen content in the sputtering gas. The Sb incorporation as doping atoms has a minor influence on the electrical, optical and structural properties. Within a narrow oxygen content in the sputtering gas highly transparent and conductive tin oxide films have been prepared. In this study, the lowest resistivity in the as deposited state is 2.9 m{omega} cm for undoped tin oxide without any postdeposition treatment. The minimum resistivity is related to a transition to crystalline films with the stoichiometry of SnO{sub 2}. At higher oxygen content the films turn out to have a higher resistivity due to an oxygen excess. After post

  4. [Magnesium and the oxidative stress].

    Science.gov (United States)

    Spasov, A A; Zheltova, A A; Kharitonov, M V

    2012-07-01

    Magnesium deficiency has been shown to result in alterations of cellular functions and biological activity of molecules. The review discusses possible relationship between Mg2+ deficiency and development of oxidative stress. Decrease of Mg2+ concentration in tissues and blood is accompanied with elevation of the oxidative stress markers, including products of the oxidative modification of lipids, proteins and DNA. The reduction in antioxidant defenses is synchronous with oxidative stress markers elevation. Different mechanisms including systemic reactions (hyperactivation of inflammation and endothelial dysfunction) and cellular changes (mitochondrial dysfunction and excessive production of fatty acids) are supposed to be involved in development and maintenance of the oxidative stress due to Mg2+ deficiency. Therefore the facts consolidated into the review evidence clear relation between Mg2+ deficiency and the oxidative stress development.

  5. Magnetic frustration of graphite oxide

    OpenAIRE

    Dongwook Lee; Jiwon Seo

    2017-01-01

    Delocalized ? electrons in aromatic ring structures generally induce diamagnetism. In graphite oxide, however, ? electrons develop ferromagnetism due to the unique structure of the material. The ? electrons are only mobile in the graphitic regions of graphite oxide, which are dispersed and surrounded by sp 3-hybridized carbon atoms. The spin-glass behavior of graphite oxide is corroborated by the frequency dependence of its AC susceptibility. The magnetic susceptibility data exhibit a negativ...

  6. Rare Earth Oxide Thin Films

    CERN Document Server

    Fanciulli, Marco

    2007-01-01

    Thin rare earth (RE) oxide films are emerging materials for microelectronic, nanoelectronic, and spintronic applications. The state-of-the-art of thin film deposition techniques as well as the structural, physical, chemical, and electrical properties of thin RE oxide films and of their interface with semiconducting substrates are discussed. The aim is to identify proper methodologies for the development of RE oxides thin films and to evaluate their effectiveness as innovative materials in different applications.

  7. In-Situ Chemical Oxidation

    Science.gov (United States)

    2006-08-01

    pH, buffer capacity , electrode potential (Eh), permeability, cation exchange capacity, natural metals, oxidant impurities, and local uses for the...driven oxidation of organic contaminants. The buffer capacity in most aquifers represents significant acid-neu- tralizing capacity and maintains...mobilized during ISCO. pH, Buffer Capacity To assess whether pH modification is needed; acidic pH (3 to 5) is optimal for Fenton oxidation; pH

  8. Zinc oxide varistors and/or resistors

    Science.gov (United States)

    Arnold, Jr., Wesley D.; Bond, Walter D.; Lauf, Robert J.

    1993-01-01

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

  9. Pristine graphite oxide.

    Science.gov (United States)

    Dimiev, Ayrat; Kosynkin, Dmitry V; Alemany, Lawrence B; Chaguine, Pavel; Tour, James M

    2012-02-08

    Graphite oxide (GO) is a lamellar substance with an ambiguous structure due to material complexity. Recently published GO-related studies employ only one out of several existing models to interpret the experimental data. Because the models are different, this leads to confusion in understanding the nature of the observed phenomena. Lessening the structural ambiguity would lead to further developments in functionalization and use of GO. Here, we show that the structure and properties of GO depend significantly on the quenching and purification procedures, rather than, as is commonly thought, on the type of graphite used or oxidation protocol. We introduce a new purification protocol that produces a product that we refer to as pristine GO (pGO) in contrast to the commonly known material that we will refer to as conventional GO (cGO). We explain the differences between pGO and cGO by transformations caused by reaction with water. We produce ultraviolet-visible spectroscopic, Fourier transform infrared spectroscopic, solid-state nuclear magnetic resonance spectroscopic, thermogravimetric, and scanning electron microscopic analytical evidence for the structure of pGO. This work provides a new explanation for the acidity of GO solutions and allows us to add critical details to existing GO models.

  10. Interface-confined oxide nanostructures for catalytic oxidation reactions.

    Science.gov (United States)

    Fu, Qiang; Yang, Fan; Bao, Xinhe

    2013-08-20

    Heterogeneous catalysts, often consisting of metal nanoparticles supported on high-surface-area oxide solids, are common in industrial chemical reactions. Researchers have increasingly recognized the importance of oxides in heterogeneous catalysts: that they are not just a support to help the dispersion of supported metal nanoparticles, but rather interact with supported metal nanoparticles and affect the catalysis. The critical role of oxides in catalytic reactions can become very prominent when oxides cover metal surfaces forming the inverse catalysts. The source of the catalytic activity in homogeneous catalysts and metalloenzymes is often coordinatively unsaturated (CUS) transition metal (TM) cations, which can undergo facile electron transfer and promote catalytic reactions. Organic ligands and proteins confine these CUS cations, making them highly active and stable. In heterogeneous catalysis, however, confining these highly active CUS centers on an inorganic solid so that they are robust enough to endure the reaction environment while staying flexible enough to perform their catalysis remains a challenge. In this Account, we describe a strategy to confine the active CUS centers on the solid surface at the interface between a TM oxide (TMO) and a noble metal (NM). Among metals, NMs have high electron negativity and low oxygen affinity. This means that TM cations of the oxide bind strongly to NM atoms at the interface, forming oxygen-terminated-bilayer TMO nanostructures. The resulting CUS sites at the edges of the TMO nanostructure are highly active for catalytic oxidation reactions. Meanwhile, the strong interactions between TMOs and NMs prevent further oxidation of the bilayer TMO phases, which would otherwise result in the saturation of oxygen coordination and the deactivation of the CUS cations. We report that we can also tune the oxide-metal interactions to modulate the bonding of reactants with CUS centers, optimizing their catalytic performance. We

  11. Metabolism of Nitrogen Oxides in Ammonia-Oxidizing Bacteria

    Science.gov (United States)

    Kozlowski, J.; Stein, L. Y.

    2014-12-01

    Ammonia-oxidizing bacteria (AOB) are key microorganisms in the transformation of nitrogen intermediates in most all environments. Until recently there was very little work done to elucidate the physiology of ammonia-oxidizing bacteria cultivated from variable trophic state environments. With a greater variety of ammonia-oxidizers now in pure culture the importance of comparative physiological and genomic analysis is crucial. Nearly all known physiology of ammonia-oxidizing bacteria lies within the Nitrosomonas genus with Nitrosomonas europaea strain ATCC 19718 as the model. To more broadly characterize and understand the nature of obligate ammonia chemolithotrophy and the contribution of AOB to production of nitrogen oxides, Nitrosomonas spp. and Nitrosospira spp. isolated from variable trophic states and with sequenced genomes, were utilized. Instantaneous ammonia- and hydroxylamine-oxidation kinetics as a function of oxygen and substrate concentration were measured using an oxygen micro-sensor. The pathway intermediates nitric oxide and nitrous oxide were measured in real time using substrate-specific micro-sensors to elucidate whether production of these molecules is stoichiometric with rates of substrate oxidation. Genomic inventory was compared among the strains to identify specific pathways and modules to explain physiological differences in kinetic rates and production of N-oxide intermediates as a condition of their adaptation to different ammonium concentrations. This work provides knowledge of how nitrogen metabolism is differentially controlled in AOB that are adapted to different concentrations of ammonium. Overall, this work will provide further insight into the control of ammonia oxidizing chemolithotrophy across representatives of the Nitrosomonas and Nitrosospira genus, which can then be applied to examine additional genome-sequenced AOB isolates.

  12. Magnetic frustration of graphite oxide

    Science.gov (United States)

    Lee, Dongwook; Seo, Jiwon

    2017-03-01

    Delocalized π electrons in aromatic ring structures generally induce diamagnetism. In graphite oxide, however, π electrons develop ferromagnetism due to the unique structure of the material. The π electrons are only mobile in the graphitic regions of graphite oxide, which are dispersed and surrounded by sp3-hybridized carbon atoms. The spin-glass behavior of graphite oxide is corroborated by the frequency dependence of its AC susceptibility. The magnetic susceptibility data exhibit a negative Curie temperature, field irreversibility, and slow relaxation. The overall results indicate that magnetic moments in graphite oxide slowly interact and develop magnetic frustration.

  13. Intercalating oleylamines in graphite oxide.

    Science.gov (United States)

    Yang, Kaikun; Liang, Si; Zou, Lianfeng; Huang, Liwei; Park, Cheol; Zhu, Lisheng; Fang, Jiye; Fu, Qiang; Wang, Howard

    2012-02-07

    Graphite oxide has been synthesized from raw graphite particles and been treated with various mass amounts of oleylamine as intercalants to form intercalation compounds. X-ray diffraction patterns reveal that the inter-sheet distances strongly depend on the graphite oxide to oleylamine mass ratios. The equilibrium-like behavior implies diffusion-dominated oleylamine adsorption on graphite oxide in solution and excluded volume intercalations among oleylamine-adsorbed graphite oxide during restacking. The intercalation compounds are soluble in organic solvents, and their applications in the fabrication of transparent and conductive coatings have been demonstrated.

  14. Trends in reactivity of oxides

    DEFF Research Database (Denmark)

    Toftelund, Anja

    , and I) and OH on a wide range of rutile oxide surfaces. Furthermore, Brønsted-Evans-Polanyi (BEP) relations are found for the adsorption of a large number of molecules (including Cl, Br and I) on transition metal oxides. In these relations the activation energies scale linearly with the dissociative...... chemisorption energies. It turns out that the BEP relation for rutile oxides is almost coinciding with the dissociation line, i.e. no barrier exists for the reactive surfaces. The heterogeneous catalytic oxidation of hydrogen halides (HCl, HBr, and HI) is investigated. A micro-kinetic model is solved...

  15. Plasma electrolytic oxidation of tantalum

    Directory of Open Access Journals (Sweden)

    Petković Marija

    2012-01-01

    Full Text Available This paper is a review of our research on the plasma electrolytic oxidation (PEO process of tantalum in 12-tungstosilicic acid. For the characterization of microdischarges during PEO, real-time imaging and optical emission spectroscopy (OES were used. The surface morphology, chemical and phase composition of oxide coatings were investigated by AFM, SEM-EDS and XRD. Oxide coating morphology is strongly dependent on PEO time. The elemental components of PEO coatings are Ta, O, Si and W. The oxide coatings are partly crystallized and mainly composed of WO3, Ta2O5 and SiO2.

  16. Semiconductor-oxide heterostructured nanowires using postgrowth oxidation.

    Science.gov (United States)

    Wallentin, Jesper; Ek, Martin; Vainorious, Neimantas; Mergenthaler, Kilian; Samuelson, Lars; Pistol, Mats-Erik; Reine Wallenberg, L; Borgström, Magnus T

    2013-01-01

    Semiconductor-oxide heterointerfaces have several electron volts high-charge carrier potential barriers, which may enable devices utilizing quantum confinement at room temperature. While a single heterointerface is easily formed by oxide deposition on a crystalline semiconductor, as in MOS transistors, the amorphous structure of most oxides inhibits epitaxy of a second semiconductor layer. Here, we overcome this limitation by separating epitaxy from oxidation, using postgrowth oxidation of AlP segments to create axial and core-shell semiconductor-oxide heterostructured nanowires. Complete epitaxial AlP-InP nanowire structures were first grown in an oxygen-free environment. Subsequent exposure to air converted the AlP segments into amorphous aluminum oxide segments, leaving isolated InP segments in an oxide matrix. InP quantum dots formed on the nanowire sidewalls exhibit room temperature photoluminescence with small line widths (down to 15 meV) and high intensity. This optical performance, together with the control of heterostructure segment length, diameter, and position, opens up for optoelectrical applications at room temperature.

  17. Direct Coal Oxidation in Modified Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Deleebeeck, Lisa; Gil, Vanesa; Ippolito, Davide

    2017-01-01

    Hybrid direct carbon fuel cells employ a classical solid oxide fuel cell together with carbon dispersed in a carbonate melt on the anode side. In a European project, the utilization of various coals has been investigated with and without addition of an oxidation catalyst to the carbon-carbonate s...

  18. Direct Coal Oxidation in Modified Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Deleebeeck, Lisa; Gil, Vanesa; Ippolito, Davide

    2015-01-01

    Hybrid direct carbon fuel cells employ a classical solid oxide fuel cell together with carbon dispersed in a carbonate melt on the anode side. In a European project, the utilization of various coals has been investigated with and without addition of an oxidation catalyst to the carbon-carbonate s...

  19. It has been suggested that oxidative stress, especially oxidative ...

    African Journals Online (AJOL)

    nabipour

    2012-02-14

    Feb 14, 2012 ... Oxidative stress has been implicated in coronary artery disease (CAD). Malondialdehyde (MDA) is lipid peroxidation end product. Bilirubin may act as an antioxidant that suppresses lipid oxidation. The role of MDA and antioxidant capacity and their inter-relationship in patients with and without CAD was.

  20. Catalysis by Thin Oxide Films and Oxide Nanoparticles

    Science.gov (United States)

    Rupprechter, Günther; Penner, Simon

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

  1. Catalytic water oxidation: Rugged water-oxidation anodes

    Science.gov (United States)

    Llobet, Antoni

    2010-10-01

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

  2. Protective effect of nitric oxide against arsenic-induced oxidative ...

    African Journals Online (AJOL)

    Nitric oxide (NO) is a key molecule involved in many physiology processes. The effects of NO on alleviating arsenic-induced oxidative damage in tall fescue leaves were investigated. Arsenic (25 M) treatment induced significantly accumulation of reactive oxygen species (ROS) and led to serious lipid peroxidation in tall ...

  3. EDITORIAL: Oxide semiconductors

    Science.gov (United States)

    Kawasaki, M.; Makino, T.

    2005-04-01

    non-equilibrium growth has rekindled the recent extensive investigation and progress in the field of ZnO epitaxy. In this special issue, Ohtomo and Tsukazaki, Cho et al, and Yi et al, respectively, describe the various fabrication processes such as pulsed laser deposition, molecular-beam epitaxy and metal-organic chemical vapour deposition. It should be noted that the last work among the above-mentioned papers has the potential to pave the way to nano-technology based on ZnO. This material has found other important applications as well, such as transparent conducting oxides (TCO). This field has a long research history, as is reviewed by Minami. Relatively speaking, ZnO was one of the earliest crystals (after Si, Ge, and InSb) to be prepared in a pure form, and the resultant long research history has given rise to the availability of large-area substrates. Recent progress in this topic is explained by two representative groups of authors in this field: Nause and Nemeth at Cermet Inc., and Maeda et al at Tokyo Denpa Co. Ltd. In order to overcome the bottleneck of p-type conduction and control the material's properties, a clear understanding of the physical processes in ZnO is necessary. Look et al are known as the first group to report on the growth and properties of p-type ZnO layers with a valid and reasonable set of experimental data (2002 Appl. Phys. Lett. 81 1830). Here, Look contributes a more comprehensive review to this issue. Optical studies on single crystals were conducted and are reviewed here by Meyer et al and Chichibu et al. Band-gap engineering and fabrication of heterojunction or quantum structures are important technological issues. It should be emphasized that by choosing an appropriate set of concentrations (x and y), perfect lattice-matching between MgxZn1-xO and CdyZn1-yO can be attained (Makino T et al 2001 Appl. Phys. Lett. 78 1237). Exciton properties of multiple quantum well structures are reported by Makino et al in this issue. Other than

  4. Ferromagnet / superconductor oxide superlattices

    Science.gov (United States)

    Santamaria, Jacobo

    2006-03-01

    The growth of heterostructures combining oxide materials is a new strategy to design novel artificial multifunctional materials with interesting behaviors ruled by the interface. With the (re)discovery of colossal magnetoresistance (CMR) materials, there has been renewed interest in heterostructures involving oxide superconductors and CMR ferromagnets where ferromagnetism (F) and superconductivity (S) compete within nanometric distances from the interface. In F/S/F structures involving oxides, interfaces are especially complex and various factors like interface disorder and roughness, epitaxial strain, polarity mismatch etc., are responsible for depressed magnetic and superconducting properties at the interface over nanometer length scales. In this talk I will focus in F/S/F structures made of YBa2Cu3O7 (YBCO) and La0.7Ca0.3MnO3 (LCMO). The high degree of spin polarization of the LCMO conduction band, together with the d-wave superconductivity of the YBCO make this F/S system an adequate candidate for the search of novel spin dependent effects in transport. We show that superconductivity at the interface is depressed by various factors like charge transfer, spin injection or ferromagnetic superconducting proximity effect. I will present experiments to examine the characteristic distances of the various mechanisms of superconductivity depression. In particular, I will discuss that the critical temperature of the superconductor depends on the relative orientation of the magnetization of the F layers, giving rise to a new giant magnetoresistance effect which might be of interest for spintronic applications. Work done in collaboration with V. Peña^1, Z. Sefrioui^1, J. Garcia-Barriocanal^1, C. Visani^1, D. Arias^1, C. Leon^1 , N. Nemes^2, M. Garcia Hernandez^2, S. G. E. te Velthuis^3, A. Hoffmann^3, M. Varela^4, S. J. Pennycook^4. Work supported by MCYT MAT 2005-06024, CAM GR- MAT-0771/2004, UCM PR3/04-12399 Work at Argonne supported by the Department of Energy, Basic

  5. Operation of staged membrane oxidation reactor systems

    Science.gov (United States)

    Repasky, John Michael

    2012-10-16

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

  6. Effects of Oxidation on Oxidation-Resistant Graphite

    Energy Technology Data Exchange (ETDEWEB)

    Windes, William [Idaho National Lab. (INL), Idaho Falls, ID (United States); Smith, Rebecca [Idaho National Lab. (INL), Idaho Falls, ID (United States); Carroll, Mark [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-05-01

    The Advanced Reactor Technology (ART) Graphite Research and Development Program is investigating doped nuclear graphite grades that exhibit oxidation resistance through the formation of protective oxides on the surface of the graphite material. In the unlikely event of an oxygen ingress accident, graphite components within the VHTR core region are anticipated to oxidize so long as the oxygen continues to enter the hot core region and the core temperatures remain above 400°C. For the most serious air-ingress accident which persists over several hours or days the continued oxidation can result in significant structural damage to the core. Reducing the oxidation rate of the graphite core material during any air-ingress accident would mitigate the structural effects and keep the core intact. Previous air oxidation testing of nuclear-grade graphite doped with varying levels of boron-carbide (B4C) at a nominal 739°C was conducted for a limited number of doped specimens demonstrating a dramatic reduction in oxidation rate for the boronated graphite grade. This report summarizes the conclusions from this small scoping study by determining the effects of oxidation on the mechanical strength resulting from oxidation of boronated and unboronated graphite to a 10% mass loss level. While the B4C additive did reduce mechanical strength loss during oxidation, adding B4C dopants to a level of 3.5% or more reduced the as-fabricated compressive strength nearly 50%. This effectively minimized any benefits realized from the protective film formed on the boronated grades. Future work to infuse different graphite grades with silicon- and boron-doped material as a post-machining conditioning step for nuclear components is discussed as a potential solution for these challenges in this report.

  7. Optical properties and electronic transitions of zinc oxide, ferric oxide, cerium oxide, and samarium oxide in the ultraviolet and extreme ultraviolet

    DEFF Research Database (Denmark)

    Pauly, N; Yubero, F; Espinós, J P

    2017-01-01

    Optical properties and electronic transitions of four oxides, namely zinc oxide, ferric oxide, cerium oxide, and samarium oxide, are determined in the ultraviolet and extreme ultraviolet by reflection electron energy loss spectroscopy using primary electron energies in the range 0.3-2.0 keV. This...

  8. 21 CFR 184.1545 - Nitrous oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Nitrous oxide. 184.1545 Section 184.1545 Food and... Substances Affirmed as GRAS § 184.1545 Nitrous oxide. (a) Nitrous oxide (empirical formula N2O, CAS Reg. No.... Nitrous oxide is manufactured by the thermal decomposition of ammonium nitrate. Higher oxides of nitrogen...

  9. Preface: Oxide Surfaces

    Science.gov (United States)

    Willmott, Phil

    2008-07-01

    Although the history of metal oxides and their surfaces goes back several decades to landmark studies, such as Mott and Peierls' explanation of electrical insulation in materials that are predicted in band theory to be conducting, or the observation by Morin of the superfast metal-to-insulator transition in vanadium dioxide, it is only in the last two decades that the world of condensed matter physics has become increasingly dominated by research into complex metal oxides. This has been driven most notably by an attempt to better understand and describe the fundamental physical processes behind their seemingly endless spectrum of properties, which in turn has also led to the discovery of novel phenomena, most prominently demonstrated by the discovery of high-temperature superconductivity in 1986, colossal magnetoresistance in 1994, and most recently, the formation of a two-dimensional conducting layer at the interface between two band insulators in 2004. One important reason why metal oxides, particularly in the form of thin films, have become such a popular subject for basic condensed matter research is that they offer a uniquely versatile materials base for the development of novel technologies. They owe this versatility both to the many different elemental combinations that lead to structurally similar forms, and also to the fact that in many cases, the strong interaction between the valence electrons means that there is a subtle interplay between structure and magnetic and electronic properties. This aspect has led in recent years to the birth or renaissance of research fields such as spintronics, orbital ordering, and multiferroics. Surfaces and interfaces are especially interesting in these strongly-correlated electron systems, where the rearrangement of electrical charge resulting from a minimization of surface or interfacial energy can have unexpected and often exciting consequences. Indeed, as the drive to miniaturize devices well below the micron size

  10. Nitric oxide: an overview.

    Science.gov (United States)

    Rodeberg, D A; Chaet, M S; Bass, R C; Arkovitz, M S; Garcia, V F

    1995-09-01

    Nitric oxide (NO), a paracrine-acting gas enzymatically synthesized from L-arginine, is a unique biologic mediator that has been implicated in a myriad of physiologic and pathophysiologic states. It is an important regulator of vascular tone and may be the mediator of the hemodynamic changes involved in sepsis and cirrhosis. In addition, there is increasing evidence that NO is involved in coagulation, immune function, inhibitory innervation of the gastrointestinal tract, protection of gastrointestinal mucosa, and the hepatotoxicity of cirrhosis. It has already been speculated that NO may represent a point of control or intervention in a number of disease states. The purpose of this paper is to provide the surgeon with a broad overview of the scientific and clinical aspects of this important molecule.

  11. Zinc Oxide Nanoparticle Photodetector

    Directory of Open Access Journals (Sweden)

    Sheng-Po Chang

    2012-01-01

    Full Text Available A zinc oxide (ZnO nanoparticle photodetector was fabricated using a simple method. Under a 5 V applied bias, its dark current and photocurrent were 1.98×10-8 and 9.42×10-7 A, respectively. In other words, a photocurrent-to-dark-current contrast ratio of 48 was obtained. Under incident light at a wavelength of 375 nm and a 5 V applied bias, the detector’s measured responsivity was 3.75 A/W. The transient time constants measured during the turn-ON and turn-OFF states were τON=204 s and τOFF=486 s, respectively.

  12. Ultra Supercritical Steamside Oxidation

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-01-01

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

  13. Phosphine oxide surfactants revisited.

    Science.gov (United States)

    Stubenrauch, Cosima; Preisig, Natalie; Laughlin, Robert G

    2016-04-01

    This review summarizes everything we currently know about the nonionic surfactants alkyl dimethyl (C(n)DMPO) and alkyl diethyl (C(n)DEPO) phosphine oxide (PO surfactants). The review starts with the synthesis and the general properties (Section 2) of these compounds and continues with their interfacial properties (Section 3) such as surface tension, surface rheology, interfacial tension and adsorption at solid surfaces. We discuss studies on thin liquid films and foams stabilized by PO surfactants (Section 4) as well as studies on their self-assembly into lyotropic liquid crystals and microemulsions, respectively (Section 5). We aim at encouraging colleagues from both academia and industry to take on board PO surfactants whenever possible and feasible because of their broad variety of excellent properties. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Main Oxidizer Valve Design

    Science.gov (United States)

    Addona, Brad; Eddleman, David

    2015-01-01

    A developmental Main Oxidizer Valve (MOV) was designed by NASA-MSFC using additive manufacturing processes. The MOV is a pneumatically actuated poppet valve to control the flow of liquid oxygen to an engine's injector. A compression spring is used to return the valve to the closed state when pneumatic pressure is removed from the valve. The valve internal parts are cylindrical in shape, which lends itself to traditional lathe and milling operations. However, the valve body represents a complicated shape and contains the majority of the mass of the valve. Additive manufacturing techniques were used to produce a part that optimized mass and allowed for design features not practical with traditional machining processes.

  15. Solid Oxide Electrolyser Cell

    DEFF Research Database (Denmark)

    Jensen, Søren Højgaard

    Solid oxide fuel cells (SOFCs) produced at Risø National Laboratory was tested as steam electrolysers under various current densities, operating temperatures and steam partial pressures. At 950 °C and a cell voltage of 1.48V the current density was -3.6A/cm2 with app. 30% H2 + 70% H2O in the inlet...... it is possible to achieve a production price of 0.7 US$/kg H2 with an electricity price of 1.3 US¢/kWh. The cell voltage was measured as function of time. In test ofabout two month of duration a long-term degradation was observed. At 850 °C, -0.5 A/cm2 with 50 vol% H2 the degradation rate was app. 20 mV/1000h...

  16. Solid Oxide Fuel Cells

    Science.gov (United States)

    Brown, Jack T.

    Solid oxide fuel cells offer the potential for high efficiency, low cost electric power plants for many applications. The fuel cell generator Itself is an all solid state reactor operating at about 1000°C, which produces direct current electricity from the conversion of the energy in gaseous fuel by an electrochemical reaction with the oxygen in air. System studies have shown 50-60 percent efficiency can be obtained in multi-megawatt all electric power plants in which the high quality exhaust heat is used to produce electricity In a bottoming cycle. Alternatively the exhaust heat can be used in Industrial and commercial co-generation systems for space cooling or raising high pressure steam. Space based and military applications for electric power plants have been proposed with high power per unit weight and volume designs which use hydrogen fuel and pure oxygen. Truly significant accomplishments have been made in the 1980's in the technological development of the special materials and processes for producing them for the various cell designs and in the conception of device designs. These advancements were due to the fundamental work of the several decades earlier. In 1986 through 1988 experimental test units in the several hundred to several thousand watt sizes have been designed, fabricated, shipped, and tested for thousands of hours by user organizations in the United States and Japan. The extent of the commercial market for Solid Oxide fuel cells for various applications, vis-a-vis alternate electrical generation options, will depend on what system capital cost can be achieved.

  17. Catalytic oxidations by vanadium complexes

    NARCIS (Netherlands)

    Ligtenbarg, A.G J; Hage, R.; Feringa, B.L.

    Vanadium haloperoxidases catalyse the oxidation of halides leading to halogenation of substrates or, in the absence of suitable substrates, to oxidation of hydrogen peroxide into singlet oxygen and water. Furthermore, V-haloperoxidases are capable to give enantioselective sulfoxidation under the

  18. Durability of Solid Oxide Cells

    DEFF Research Database (Denmark)

    Knibbe, Ruth; Hauch, Anne; Hjelm, Johan

    2011-01-01

    In recent years extended focus has been placed on monitoring and understanding degradation mechanisms in both solid oxide fuel cells and solid oxide electrolysis cells. The time-consuming nature of degradation experiments and the disparate conclusions from experiment reproductions indicates...

  19. Nitrous oxide and perioperative outcomes.

    Science.gov (United States)

    Ko, Hanjo; Kaye, Alan David; Urman, Richard D

    2014-06-01

    There is emerging evidence related to the effects of nitrous oxide on important perioperative patient outcomes. Proposed mechanisms include metabolic effects linked to elevated homocysteine levels and endothelial dysfunction, inhibition of deoxyribonucleic acid and protein formation, and depression of chemotactic migration by monocytes. Newer large studies point to possible risks associated with the use of nitrous oxide, although data are often equivocal and inconclusive. Cardiovascular outcomes such as stroke or myocardial infarction were shown to be unchanged in previous studies, but the more recent Evaluation of Nitrous Oxide in the Gas Mixture for Anesthesia I trial shows possible associations between nitrous oxide and increased cardiovascular and pulmonary complications. There are also possible effects on postoperative wound infections and neuropsychological function, although the multifactorial nature of these complications should be considered. Teratogenicity linked to nitrous oxide use has not been firmly established. The use of nitrous oxide for routine anesthetic care may be associated with significant costs if complications such as nausea, vomiting, and wound infections are taken into consideration. Overall, definitive data regarding the effect of nitrous oxide on major perioperative outcomes are lacking. There are ongoing prospective studies that may further elucidate its role. The use of nitrous oxide in daily practice should be individualized to each patient's medical conditions and risk factors.

  20. Nitric Oxide: The Wonder Molecule

    Indian Academy of Sciences (India)

    (heart attack) and hypertension. Nitric oxide (NO), an inorganic molecule formed by vascular endothelial cells is now thought to be a messenger molecule that is believed to playa crucial role in various biological processes of both physiological and pathological importance. Nitric oxide is a simple heterodiatomic molecule ...

  1. Oxidative stress from environmental pollutants.

    Science.gov (United States)

    Ahmad, S

    1995-01-01

    Recently progress has been made on O2 toxicity and pathology related to numerous environmental contaminants in insects. The pro-oxidants studied included: dioxin, paraquat, and an assorted array of quinones, 8-methoxypsorlen, arsenic, and mercury. The responses to these oxidants are diverse, but they arise from the reactive oxygen species. These pro-oxidants in insects cause lipid peroxidation, protein and enzyme oxidation, and GSH depletion. Potentially, they may also cause DNA oxidation, and form DNA adducts. Oxidative challenge is alleviated by antioxidant compounds, but more importantly by the induction of antioxidant enzymes, which are crucial for the termination of O2 radical cascade and lipid peroxidation chain reaction. Insects exhibit a wasting syndrome under sub-acute stress. In acute toxicity vital physiological processes impaired are hemolymph melanization and diuresis. Thus, insects resemble vertebrates in both the response to oxidative stress and its pathological consequences. These results raise the prospect that insects may serve as non-mammalian model species for monitoring the oxidative-stress component of environmental toxicity.

  2. Oxide fiber targets at ISOLDE

    DEFF Research Database (Denmark)

    Köster, U.; Bergmann, U.C.; Carminati, D.

    2003-01-01

    Many elements are rapidly released from oxide matrices. Some oxide powder targets show a fast sintering, thus losing their favorable release characteristics. Loosely packed oxide fiber targets are less critical since they may maintain their open structure even when starting to fuse together at some...... contact points. The experience with various oxide fiber targets (titania, zirconia, ceria and thoria) used in the last years at ISOLDE is reviewed. For short-lived isotopes of Cu, Ga and Xe the zirconia and ceria targets respectively provided significantly higher yields than any other target (metal foils......, oxide powders, etc.) tested before. Titania fibers, which were not commercially available, were produced in a relic process by impregnation of a rayon felt in a titanium chloride solution and subsequent calcination by heating the dried felt in air. Thoria fibers were obtained either by the same process...

  3. Catalysis by nitric oxide synthase.

    Science.gov (United States)

    Marletta, M A; Hurshman, A R; Rusche, K M

    1998-10-01

    The enzyme nitric oxide synthase catalyzes the oxidation of the amino acid L-arginine to L-citrulline and nitric oxide in an NADPH-dependent reaction. Nitric oxide plays a critical role in signal transduction pathways in the cardiovascular and nervous systems and is a key component of the cytostatic/cytotoxic function of the immune system. Characterization of nitric oxide synthase substrates and cofactors has outlined the broad details of the overall reaction and suggested possibilities for chemical steps in the reaction; however, the molecular details of the reaction mechanism are still poorly understood. Recent evidence suggests a role for the reduced bound pterin in the first step of the reaction--the hydroxylation of L-arginine.

  4. Oxidative stability of marine phospholipids

    DEFF Research Database (Denmark)

    Lu, Henna Fung Sieng; Nielsen, Nina Skall; Baron, Caroline Pascale

    Many studies have shown that marine phospholipids (MPL) provide more advantages than fish oil. They have better bioavailability, better resistance towards oxidation and higher content of eicosapentaenoic acids (EPA) and docosahexaenoic acids (DHA) than oily triglycerides (fish oil). The objective...... of this study is to investigate the oxidative and hydrolytic stability of MPL. In addition, this study also investigates the effect of chemical composition of MPL and Maillard reaction (interaction between lipids oxidation products with the residue of amino acids) on MPL emulsions’ stability. Firstly, MPL were...... prepared in the form of emulsions by high pressure homogenizer. Then, the oxidative and hydrolytic stability of phospholipids was investigated by measurement of simple chemical analyses such as Peroxide Value and Free Fatty Acids, and 31PNMR after 32 days storage at 2ºC. The oxidative stability of MPL...

  5. Selective catalytic oxidation of ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Leppaelahti, J.; Koljonen, T. [VTT Energy, Espoo (Finland)

    1996-12-31

    In the combustion of fossil fuels, the principal source of nitrogen oxides is nitrogen bound in the fuel structure. In gasification, a large part of fuel nitrogen forms NH{sub 3}, which may form nitrogen oxides during gas combustion. If NH{sub 3} and other nitrogen species could be removed from hot gas, the NO emission could be considerably reduced. However, relatively little attention has been paid to finding new means of removing nitrogen compounds from the hot gasification gas. The possibility of selectively oxidizing NH{sub 3} to N{sub 2} in the hot gasification has been studied at VTT Energy. The largest NH{sub 3} reductions have been achieved by catalytic oxidation on aluminium oxides. (author) (4 refs.)

  6. Van der Waals oxide heteroepitaxy

    Science.gov (United States)

    Chu, Ying-Hao

    2017-12-01

    The research field of oxide heteroepitaxy suffers from the characteristics of misfit strain and substrate clamping, hampering the optimization of performance and the gain of fundamental understanding of oxide systems. Recently, there are demonstrations on functional oxides epitaxially fabricated on layered muscovite substrate. In these heterostructures, due to the weak interaction between substrate and film, they show the lattice of films close to bulk with excellent strictive properties, suggesting that these critical problems can be potentially solved by van der Waals oxide heteroepitaxy. In addition, by exploiting the transparent and flexible features of muscovite, such a heteroepitaxy can deliver new material solutions to transparent soft technology. In this paper, the history, development, and current status of van der Waals oxide heteroepitaxy are addressed and discussed. In the end, new research directions in terms of fundamental study and practical application are proposed to highlight the importance of this research field.

  7. BRCA1 and Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Yong Weon Yi

    2014-04-01

    Full Text Available The breast cancer susceptibility gene 1 (BRCA1 has been well established as a tumor suppressor and functions primarily by maintaining genome integrity. Genome stability is compromised when cells are exposed to oxidative stress. Increasing evidence suggests that BRCA1 regulates oxidative stress and this may be another mechanism in preventing carcinogenesis in normal cells. Oxidative stress caused by reactive oxygen species (ROS is implicated in carcinogenesis and is used strategically to treat human cancer. Thus, it is essential to understand the function of BRCA1 in oxidative stress regulation. In this review, we briefly summarize BRCA1’s many binding partners and mechanisms, and discuss data supporting the function of BRCA1 in oxidative stress regulation. Finally, we consider its significance in prevention and/or treatment of BRCA1-related cancers.

  8. Nanotoxicology of Metal Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    Amedea B. Seabra

    2015-06-01

    Full Text Available This review discusses recent advances in the synthesis, characterization and toxicity of metal oxide nanoparticles obtained mainly through biogenic (green processes. The in vitro and in vivo toxicities of these oxides are discussed including a consideration of the factors important for safe use of these nanomaterials. The toxicities of different metal oxide nanoparticles are compared. The importance of biogenic synthesized metal oxide nanoparticles has been increasing in recent years; however, more studies aimed at better characterizing the potent toxicity of these nanoparticles are still necessary for nanosafely considerations and environmental perspectives. In this context, this review aims to inspire new research in the design of green approaches to obtain metal oxide nanoparticles for biomedical and technological applications and to highlight the critical need to fully investigate the nanotoxicity of these particles.

  9. 21 CFR 172.808 - Copolymer condensates of ethylene oxide and propylene oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Copolymer condensates of ethylene oxide and propylene oxide. 172.808 Section 172.808 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH... ethylene oxide and propylene oxide. Copolymer condensates of ethylene oxide and propylene oxide may be...

  10. Catalyst for Decomposition of Nitrogen Oxides

    Science.gov (United States)

    Schryer, David R. (Inventor); Jordan, Jeffrey D. (Inventor); Akyurtlu, Ates (Inventor); Akyurtlu, Jale (Inventor)

    2015-01-01

    This invention relates generally to a platinized tin oxide-based catalyst. It relates particularly to an improved platinized tin oxide-based catalyst able to decompose nitric oxide to nitrogen and oxygen without the necessity of a reducing gas.

  11. Test Concept for Advanced Oxidation Techniques

    DEFF Research Database (Denmark)

    Bennedsen, Lars Rønn; Søgaard, Erik Gydesen; Mortensen, Lars

    advanced on-site oxidation tests. The remediation techniques included are electrochemical oxidation, photochemical/photocatalytic oxidation, ozone, hydrogen peroxide, permanganate, and persulfate among others. A versatile construction of the mobile test unit makes it possible to combine different...

  12. New developments in oxidative fermentation.

    Science.gov (United States)

    Adachi, O; Moonmangmee, D; Toyama, H; Yamada, M; Shinagawa, E; Matsushita, K

    2003-02-01

    Oxidative fermentations have been well established for a long time, especially in vinegar and in L-sorbose production. Recently, information on the enzyme systems involved in these oxidative fermentations has accumulated and new developments are possible based on these findings. We have recently isolated several thermotolerant acetic acid bacteria, which also seem to be useful for new developments in oxidative fermentation. Two different types of membrane-bound enzymes, quinoproteins and flavoproteins, are involved in oxidative fermentation, and sometimes work with the same substrate but produce different oxidation products. Recently, there have been new developments in two different oxidative fermentations, D-gluconate and D-sorbitol oxidations. Flavoproteins, D-gluconate dehydrogenase, and D-sorbitol dehydrogenase were isolated almost 2 decades ago, while the enzyme involved in the same oxidation reaction for D-gluconate and D-sorbitol has been recently isolated and shown to be a quinoprotein. Thus, these flavoproteins and a quinoprotein have been re-assessed for the oxidation reaction. Flavoprotein D-gluconate dehydrogenase and D-sorbitol dehydrogenase were shown to produce 2-keto- D-gluconate and D-fructose, respectively, whereas the quinoprotein was shown to produce 5-keto- D-gluconate and L-sorbose from D-gluconate and D-sorbitol, respectively. In addition to the quinoproteins described above, a new quinoprotein for quinate oxidation has been recently isolated from Gluconobacter strains. The quinate dehydrogenase is also a membrane-bound quinoprotein that produces 3-dehydroquinate. This enzyme can be useful for the production of shikimate, which is a convenient salvage synthesis system for many antibiotics, herbicides, and aromatic amino acids synthesis. In order to reduce energy costs of oxidative fermentation in industry, several thermotolerant acetic acid bacteria that can grow up to 40 degrees C have been isolated. Of such isolated strains, some

  13. Nanoparticular metal oxide/anatase catalysts

    DEFF Research Database (Denmark)

    2010-01-01

    the catalyst metai oxide is co-precipitated with the carrier metal oxide, which crystallization seeds are removed by combustion in a final calcining step. The present invention also concerns processes wherein the nanoparticular metal oxide catalysts of the invention are used, such as SCR (deNOx) reactions...... of nitrogen oxides with ammonia or urea as reductant, oxidations of alcohols or aldehydes with dioxygen or air to provide aldehydes, ketones or carboxylic acids, and photocatalytic oxidation of volatile organic compounds (VOCs)....

  14. Neutron Protection Factor Determination and Validation for a Vehicle Surrogate Using a Californium Fission Source

    Science.gov (United States)

    2017-06-01

    a 4 mm x 4 mm (0.157" x 0.157") LiI(Eu) crystal with 96% enrichment of lithium -6. The crystal is connected to a photomultiplier tube (PMT) which...32 Figure 17. Lithium -6 Iodide, Europium Doped Scintillation Detector. Source: [27...Alamos National Laboratory LiI(Eu) Lithium Iodide Europium Doped LLD Low Level Discriminator LLNL Lawrence Livermore National Laboratory MASH Monte

  15. Oxidized magnetosomes in magnetotactic bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Gehring, Andreas U., E-mail: agehring@erdw.ethz.ch [Institute of Geophysics, ETH Zurich, 8092 Zurich (Switzerland); Charilaou, Michalis, E-mail: michalis.charilaou@erdw.ethz.ch [Institute of Geophysics, ETH Zurich, 8092 Zurich (Switzerland); Garcia-Rubio, Ines, E-mail: garciarubio@phys.chem.ethz.ch [Laboratory of Physical Chemistry, ETH Zurich, 8093 Zurich (Switzerland)

    2012-04-15

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

  16. Optical properties of graphite oxide and reduced graphite oxide

    Science.gov (United States)

    Jung, Eilho; Lee, Seokbae; Roh, Seulki; Hwang, Eunhee; Lee, Junghyun; Lee, Hyoyoung; Hwang, Jungseek

    2014-07-01

    We studied the optical properties of a graphite oxide and a reduced graphite oxide by using the optical spectroscopic technique. The graphite oxide does not show a finite dc conductivity and has several characteristic absorption modes in the mid-infrared region, caused by an epoxide functional group and hydroxyl and carboxyl moieties in the mid-infrared range. The reduced graphite oxide shows a Drude-like response in the far-infrared region and the estimated dc conductivity and electric mobility are around 200 Ω-1cm-1 and ˜100 cm2V-1s-1, respectively. We found that the optical conductivity cannot be fitted with a simple Drude model, which indicates that the charge carriers are correlated. We applied an extended Drude model and obtained the optical scattering rate and the optical effective mass. We found that the optical effective mass can carry information of both the enhanced mass by correlation and the electronic band structure.

  17. Room temperature chemical oxidation of delafossite-type oxides

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-07-01

    Examination of the delafossite-type structure of CuLaO[sub 2] and CuYO[sub 2] suggests that there is room enough to accommodate intercalated oxide ions and the charge compensation resulting simply from the oxidation of an equivalent amount of Cu[sup +] into Cu[sup 2+]. Reaction with hypohalites in an aqueous solution leads to color change. Evidence of the formation of Cu[sup 2+] is given by TGA, iodometric titration, and magnetic (static and EPR) measurements. The obtained La and Y compounds seem to behave in a different way: Whereas CuLaO[sub 2+x] appears as a single phase, CuYO[sub 2+x] corresponds to a two-phase mixture, with respectively low and high x values, the latter being isostructural with the thermally oxidized compound recently reported. Comparison is stressed between the oxides obtained at higher temperatures.

  18. Selective propene oxidation on mixed metal oxide catalysts

    CERN Document Server

    James, D W

    2002-01-01

    Selective catalytic oxidation processes represent a large segment of the modern chemical industry and a major application of these is the selective partial oxidation of propene to produce acrolein. Mixed metal oxide catalysts are particularly effective in promoting this reaction, and the two primary candidates for the industrial process are based on iron antimonate and bismuth molybdate. Some debate exists in the literature regarding the operation of these materials and the roles of their catalytic components. In particular, iron antimonate catalysts containing excess antimony are known to be highly selective towards acrolein, and a variety of proposals for the enhanced selectivity of such materials have been given. The aim of this work was to provide a direct comparison between the behaviour of bismuth molybdate and iron antimonate catalysts, with additional emphasis being placed on the component single oxide phases of the latter. Studies were also extended to other antimonate-based catalysts, including coba...

  19. Tobacco Xenobiotics Release Nitric Oxide

    Directory of Open Access Journals (Sweden)

    Lam EWN

    2003-09-01

    Full Text Available Abstract Many xenobiotic compounds exert their actions through the release of free radicals and related oxidants 12, bringing about unwanted biological effects 3. Indeed, oxidative events may play a significant role in tobacco toxicity from cigarette smoke. Here, we demonstrate the direct in vitro release of the free radical nitric oxide (•NO from extracts and components of smokeless tobacco, including nicotine, nitrosonornicotine (NNN and 4-(methyl-N-nitrosamino-1-(3-pyridyl-1-butanone (NNK in phosphate buffered saline and human saliva using electron spin resonance and chemiluminescence detection. Our findings suggest that tobacco xenobiotics represent as yet unrecognized sources of •NO in the body.

  20. Synthesis of vertically aligned metal oxide nanostructures

    KAUST Repository

    Roqan, Iman S.

    2016-03-03

    Metal oxide nanostructure and methods of making metal oxide nanostructures are provided. The metal oxide nanostructures can be 1 -dimensional nanostructures such as nanowires, nanofibers, or nanotubes. The metal oxide nanostructures can be doped or undoped metal oxides. The metal oxide nanostructures can be deposited onto a variety of substrates. The deposition can be performed without high pressures and without the need for seed catalysts on the substrate. The deposition can be performed by laser ablation of a target including a metal oxide and, optionally, a dopant. In some embodiments zinc oxide nanostructures are deposited onto a substrate by pulsed laser deposition of a zinc oxide target using an excimer laser emitting UV radiation. The zinc oxide nanostructure can be doped with a rare earth metal such as gadolinium. The metal oxide nanostructures can be used in many devices including light-emitting diodes and solar cells.

  1. Study of nitric oxide catalytic oxidation on manganese oxides-loaded activated carbon at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    You, Fu-Tian [Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen (China); University of Chinese Academy of Sciences, Beijing (China); Yu, Guang-Wei, E-mail: gwyu@iue.ac.cn [Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen (China); Wang, Yin, E-mail: yinwang@iue.ac.cn [Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen (China); Xing, Zhen-Jiao [Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen (China); Liu, Xue-Jiao; Li, Jie [Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen (China); University of Chinese Academy of Sciences, Beijing (China)

    2017-08-15

    Highlights: • Loading manganese oxides on activated carbon effectively promotes NO oxidation. • NO adsorption-desorption on activated carbon is fundamental to NO oxidation. • A high Mn{sup 4+}/Mn{sup 3+} ratio contributes to NO oxidation by promoting lattice O transfer. - Abstract: Nitric oxide (NO) is an air pollutant that is difficult to remove at low concentration and low temperature. Manganese oxides (MnO{sub x})-loaded activated carbon (MLAC) was prepared by a co-precipitation method and studied as a new catalyst for NO oxidation at low temperature. Characterization of MLAC included X-ray diffraction (XRD), scanning electron microscopy (SEM), N{sub 2} adsorption/desorption and X-ray photoelectron spectroscopy (XPS). Activity tests demonstrated the influence of the amount of MnO{sub x} and the test conditions on the reaction. MLAC with 7.5 wt.% MnO{sub x} (MLAC003) exhibits the highest NO conversion (38.7%) at 1000 ppm NO, 20 vol.% O{sub 2}, room temperature and GHSV ca. 16000 h{sup −1}. The NO conversion of MLAC003 was elevated by 26% compared with that of activated carbon. The results of the MLAC003 activity test under different test conditions demonstrated that NO conversion is also influenced by inlet NO concentration, inlet O{sub 2} concentration, reaction temperature and GHSV. The NO adsorption-desorption process in micropores of activated carbon is fundamental to NO oxidation, which can be controlled by pore structure and reaction temperature. The activity elevation caused by MnO{sub x} loading is assumed to be related to Mn{sup 4+}/Mn{sup 3+} ratio. Finally, a mechanism of NO catalytic oxidation on MLAC based on NO adsorption-desorption and MnO{sub x} lattice O transfer is proposed.

  2. Oxidative Damage in Parkinson's Disease

    National Research Council Canada - National Science Library

    Beal, M

    2001-01-01

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

  3. Exploring oxidative modifications of tyrosine

    DEFF Research Database (Denmark)

    Houée-Lévin, C; Bobrowski, K; Horakova, L

    2015-01-01

    Protein oxidation is increasingly recognised as an important modulator of biochemical pathways controlling both physiological and pathological processes. While much attention has focused on cysteine modifications in reversible redox signalling, there is increasing evidence that other protein...... residues are oxidised in vivo with impact on cellular homeostasis and redox signalling pathways. A notable example is tyrosine, which can undergo a number of oxidative post-translational modifications to form 3-hydroxy-tyrosine, tyrosine crosslinks, 3-nitrotyrosine and halogenated tyrosine, with different...... effects on cellular functions. Tyrosine oxidation has been studied extensively in vitro, and this has generated detailed information about the molecular mechanisms that may occur in vivo. An important aspect of studying tyrosine oxidation both in vitro and in biological systems is the ability to monitor...

  4. COPD: balancing oxidants and antioxidants

    Science.gov (United States)

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

    2015-01-01

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

  5. Diffusion of single oxidation pond

    Directory of Open Access Journals (Sweden)

    Song Ruo-Yuan

    2016-01-01

    Full Text Available The hydraulic characteristic of an oxidation pond was studied by the tracer experiment, and an empirical formula of Peclet number was obtained, which can be well applied to the model of plug flow reactor with longitudinal diffusion.

  6. ENGINEERING BULLETIN: SUPERCRITICAL WATER OXIDATION

    Science.gov (United States)

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

  7. Resonating Nitrous Oxide Thruster Project

    Data.gov (United States)

    National Aeronautics and Space Administration — AeroAstro proposes decomposing nitrous oxide (N2O) as an alternative propellant to existing spacecraft propellants. Decomposing N2O can be used as either a high Isp,...

  8. Oxidative stress tolerance in plants

    Science.gov (United States)

    Krishnamurthy, Aparna; Rathinasabapathi, Bala

    2013-01-01

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

  9. Obesity, asthma, and oxidative stress

    National Research Council Canada - National Science Library

    Fernando Holguin; Anne Fitzpatrick

    2010-01-01

    .... Contrary to what has previously been thought, the combination of obesity and asthma, both chronic inflammatory diseases, does not necessarily result in a synergistic effect, leading to even greater oxidative stress...

  10. Oxidation dynamics of aluminum nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ying [Argonne Leadership Computing Facility, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Kalia, Rajiv K.; Nakano, Aiichiro; Vashishta, Priya [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Chemical Engineering and Materials Science, Department of Computer Science, University of Southern California, Los Angeles, California 90089-0242 (United States)

    2015-02-23

    Aluminum nanorods (Al-NRs) are promising fuels for pyrotechnics due to the high contact areas with oxidizers, but their oxidation mechanisms are largely unknown. Here, reactive molecular dynamics simulations are performed to study thermally initiated burning of oxide-coated Al-NRs with different diameters (D = 26, 36, and 46 nm) in oxygen environment. We found that thinner Al-NRs burn faster due to the larger surface-to-volume ratio. The reaction initiates with the dissolution of the alumina shell into the molten Al core to generate heat. This is followed by the incorporation of environmental oxygen atoms into the resulting Al-rich shell, thereby accelerating the heat release. These results reveal an unexpectedly active role of the alumina shell as a “nanoreactor” for oxidation.

  11. Skin aging and oxidative stress

    National Research Council Canada - National Science Library

    Ahsanuddin, Sayeeda; Lam, Minh; D. Baron, Elma

    2016-01-01

    .... Here, we review the critical role that oxidative stress plays in skin aging, including its effects on signaling pathways involved in skin matrix formation and degradation, proteasome activity, as well as DNA structure...

  12. Atomic Layer Deposition of Tin Oxide with Nitric Oxide as an Oxidant Gas

    OpenAIRE

    Heo, Jaeyeong; Gordon, Roy Gerald; Kim, Sang Bok

    2012-01-01

    Atomic layer deposition (ALD) of tin oxide \\((SnO_2)\\) thin films was achieved using a cyclic amide of Sn(II) (1,3-bis(1,1-dimethylethyl)-4,5-dimethyl-(4R,5R)-1,3,2-diazastannolidin-2-ylidene) as a tin precursor and nitric oxide (NO) as an oxidant gas. Film properties as a function of growth temperature from \\(130-250^{\\circ}C\\) were studied. Highly conducting \\(SnO_2\\) films were obtained at \\(200-250^{\\circ}C\\) with the growth per cycle of \\(~1.4 \\mathring{A}\\)/cycle, while insulating films...

  13. Sulfide oxidation in a biofilter

    DEFF Research Database (Denmark)

    Pedersen, Claus Lunde; Liu, Dezhao; Hansen, Michael Jørgen

    2012-01-01

    oxidizing bacteria but several fungal families including Trichocomaceae. A positive correlation was found between the presence of mold and sulfide uptake. However there have been no reports on fungi metabolizing hydrogen sulfide. We hypothesize that the mold increases the air exposed surface, enabling...... higher hydrogen sulfide uptake followed by oxidation catalyzed by iron-containing enzymes such as cytochrome c oxidase in a process uncoupled from energy conservation....

  14. Sulfide oxidation in a biofilter

    DEFF Research Database (Denmark)

    Pedersen, Claus Lunde; Dezhao, Liu; Hansen, Michael Jørgen

    oxidizing bacteria but several fungal families including Trichocomaceae. A positive correlation was found between the presence of mold and sulfide uptake. However there have been no reports on fungi metabolizing hydrogen sulfide. We hypothesize that the mold increases the air exposed surface, enabling...... higher hydrogen sulfide uptake followed by oxidation catalyzed by iron-containing enzymes such as cytochrome c oxidase in a process uncoupled from energy conservation....

  15. Oxide Thermoelectric Energy Harvesting Materials

    OpenAIRE

    James, Ashley

    2014-01-01

    Conventional thermoelectric materials found in many thermoelectric devices have unfavourable properties; they often suffer instability at high temperatures and contain toxic metals which pose a hazard to the environment. Oxide thermoelectric materials are stable, less toxic and could eventually replace conventional materials. The thermoelectric performance of oxide materials currently do not match conventional materials however, there is potential for improvement through doping and altering t...

  16. Myoglobin-induced oxidative damage

    DEFF Research Database (Denmark)

    Irwin, J A; Ostdal, H; Davies, Michael Jonathan

    1999-01-01

    -to-protein radical transfer and hence chain-oxidation occurs, and the factors that control these reactions. Three amino acids show significant reactivity: Tyr, Trp, and Cys, with Cys the least efficient. Evidence has also been obtained for (inefficient) hydrogen abstraction at peptide alpha-carbon sites; this may...... that protein-to-protein damage transfer and protein chain-oxidation may occur readily in biological systems....

  17. Oxidation behaviour and electrical properties of cobalt/cerium oxide composite coatings for solid oxide fuel cell interconnects

    DEFF Research Database (Denmark)

    Harthøj, Anders; Holt, Tobias; Møller, Per

    2015-01-01

    This work evaluates the performance of cobalt/cerium oxide (Co/CeO2) composite coatings and pure Co coatings to be used for solid oxide fuel cell (SOFC) interconnects. The coatings are electroplated on the ferritic stainless steels Crofer 22 APU and Crofer 22H. Coated and uncoated samples......, Mn, Fe and Cr oxide and the inner layer consisted of Cr oxide. The CeO2 was present as discrete particles in the outer oxide layer after exposure. The Cr oxide layer thicknesses and oxidations rates were significantly reduced for Co/CeO2 coated samples compared to for Co coated and uncoated samples...

  18. Oxidative Stress in Aged Rats

    Directory of Open Access Journals (Sweden)

    Damisela Ramírez Ramírez

    2013-12-01

    Full Text Available Background: aging is one of the major problems that the world is facing today due to its impact on all areas of society. Objective: to determine the concentrations of advanced oxidation protein products and malondialdehyde as indicators of oxidative damage and to determine the antioxidant defense capacity of the enzymes superoxide dismutase, catalase and the reduced glutathione concentration in aged rats. Methods: a total of 20 male Wistar rats with a body weight of approximately 200 to 250 grams were selected to form two groups with 10 young adult rats and 10 old rats. 2 ml of blood was drawn from the paranasal sinus. The sample was collected in 5 ml vials and after being homogenized, it was sent to the Biomedical Research Center, where it was used to assess the following oxidative stress variables: degree of oxidative damage and antioxidant defense level. An analysis of variance was performed to study the behavior of the different groups. Differences were considered significant when P value was less than 0.05. Results: no significant changes were found in the concentrations of malondialdehyde and glutathione, as well as in the superoxide dismutase and catalase activity in aged rats compared to young. Concentration of advanced oxidation protein products increased significantly in aged rats. Conclusions: aged rats showed an increase in oxidative damage to proteins. Antioxidant defense capacity of the enzymes superoxide dismutase and catalase and reduced glutathione concentration showed no changes.

  19. 46 CFR 154.1725 - Ethylene oxide.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Ethylene oxide. 154.1725 Section 154.1725 Shipping COAST....1725 Ethylene oxide. (a) A vessel carrying ethylene oxide must: (1) Have cargo piping, vent piping, and... space of an ethylene oxide cargo tank for a period of 30 days under the condition of paragraph (e) of...

  20. 21 CFR 73.2250 - Iron oxides.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Iron oxides. 73.2250 Section 73.2250 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2250 Iron oxides. (a) Identity. The color additives iron oxides consist of any one or any combination of synthetically prepared iron oxides, including the...

  1. 46 CFR 153.1010 - Alkylene oxides.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Alkylene oxides. 153.1010 Section 153.1010 Shipping... § 153.1010 Alkylene oxides. (a) Before each loading of a cargo containment system with a cargo... that separation of the alkylene oxide piping system complies with alkylene oxide handling plans...

  2. Oxidative DNA damage and oxidative stress in subjects occupationally exposed to nitrous oxide (N(2)O).

    Science.gov (United States)

    Wrońska-Nofer, Teresa; Nofer, Jerzy-Roch; Jajte, Jolanta; Dziubałtowska, Elżbieta; Szymczak, Wiesław; Krajewski, Wojciech; Wąsowicz, Wojciech; Rydzyński, Konrad

    2012-03-01

    Occupational exposure to nitrous oxide (N(2)O) and/or halogenated hydrocarbons has been suggested to induce damage of genetic material, but the underlying mechanisms remain obscure. This study investigated the role of oxidative processes in the genotoxicity associated with exposure to waste anaesthetic gases. The study was performed in 36 female nurses and in 36 unexposed female health care workers matched for age and employment duration. Genotoxic effects were examined by Comet test modification employing formamidopyrimidine glycosylase (FPG) that allows assessment of oxidative DNA damage. Reactive oxygen species (ROS) in leukocytes were investigated by fluorescence spectroscopy with 2',7'-dichlorofluorescin diacetate. Oxidative stress markers including 8-iso-prostaglandin F(2α) (8-iso-PGF(2α)), thiobarbituric acid-reacive substances (TBARS), α-tocopherol, and glutathione peroxidise (GPX) activity were measured immuno- or colorimetrically. N(2)O, sevoflurane and isoflurane were monitored by gas chromatography and mass spectrometry. The study documents for the first time the positive correlation between the oxidative DNA damage and the N(2)O levels in the ambient air. By contrast, no association was observed between genotoxic effects and sevoflurane or isoflurane. In addition, ROS generation and plasma and urine concentrations of TBARS and 8-iso-PGF(2α), respectively, were elevated, while GPX activity was reduced in nurses exposed to waste anaesthetic gases. Path analysis pointed to a causal relationship between N(2)O exposure, oxidative stress and DNA damage. Occupational exposure to N(2)O is associated with increased oxidative DNA damage and the level of exposure plays a critical role in this regard. Increased oxidative stress may represent a mechanistic link between chronic N(2)O exposure and genotoxicity. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Solid oxide electrolyser cell

    Energy Technology Data Exchange (ETDEWEB)

    Hoejgaard Jensen, S.

    2006-12-15

    Solid oxide fuel cells (SOFCs) produced at Riso National Laboratory was tested as steam electrolysers under various current densities, operating temperatures and steam partial pressures. At 950 deg. C and a cell voltage of 1.48V the current density was -3.6 A/cm{sup 2} with app. 30% H{sub 2} + 70% H{sub 2}O in the inlet gas and a H{sub 2}O utilization of app. 40%. The tested SOECs were also used for CO{sub 2} electrolysis. Economy studies of CO and H2 production show that especially H{sub 2} production can be competitive in areas with cheap electricity. Assuming the above described initial performance and a lifetime of 10 years it is possible to achieve a production price of 0.7 US dollar/kg H{sub 2} with an electricity price of 1.3 US cent/kWh. The cell voltage was measured as function of time. In test of about two month of duration a long-term degradation was observed. At 850 deg. C, -0.5 A/cm{sup 2} with 50 vol% H{sub 2} the degradation rate was app. 20 mV/1000h. It was shown that the degradation happens at Ni/YSZ-electrode. The long term degradation is probably caused by coarsening of the Ni-particles. After onset of electrolysis operation a transient passivation/reactivation phenomena with duration of several days was observed. It was shown that the phenomenon is attributed to the SiO{sub 2} contamination at the Ni/YSZ electrode-electrolyte interface. The SiO{sub 2} arises from the albite glass sealing (NaAlSi{sub 3}O{sub 8}) that surrounds the electrode. Si may enter the Ni/YSZ electrode via the reaction Si(OH){sub 4}(g) {r_reversible} SiO{sub 2}(l)+H{sub 2}O(g). At the active sites of the Ni/YSZ electrode steam is reduced via the reaction H{sub 2}O - 2e {yields} H{sub 2}+O{sup 2-} . This shifts the equilibrium of the first reaction to form SiO{sub 2}(l) at the active sites. After a certain time the sealing crystallizes and the SiO{sub 2}(l) evaporates from the active sites and the cell reactivates. The passivation is shown to relate to a build up of a

  4. Size of oxide vacancies in fluorite and perovskite structured oxides

    DEFF Research Database (Denmark)

    Chatzichristodoulou, Christodoulos; Norby, Poul; Hendriksen, Peter Vang

    2015-01-01

    An analysis of the effective radii of vacancies and the stoichiometric expansion coefficient is performed on metal oxides with fluorite and perovskite structures. Using the hard sphere model with Shannon ion radii we find that the effective radius of the oxide vacancy in fluorites increases...... with increasing ion radius of the host cation and that it is significantly smaller than the radius of the oxide ion in all cases, from 37% smaller for HfO2 to 13 % smaller for ThO2. The perovskite structured LaGaO3 doped with Sr or Mg or both is analyzed in some detail. The results show that the effective radius...... of an oxide vacancy in doped LaGaO3 is only about 6 % smaller than the oxide ion. In spite of this the stoichiometric expansion coefficient (a kind of chemical expansion coefficient) of the similar perovskite, LaCrO3, is significantly smaller than the stoichiometric expansion coefficient of the fluorite...

  5. OXIDATIVE STRESS AND ANTI OXIDANTS STATUS IN PELLAGRA

    Directory of Open Access Journals (Sweden)

    Desireddy Neelima, Bandi Hari Krishna, Masthan Saheb, Natham Mallikarjuna Reddy.

    2015-10-01

    Full Text Available Background and objectives: Pellagra was vanished from most parts of the world where it was formerly present due to its dietary modification. However, it is still encountered among the jowar eating populations of India. The information about the role of oxidative stress in pellagra was not established. Therefore, in this study we assessed the oxidative stress status by using malondialdehyde (MDA, total anti oxidant status (TAOS and redox ratio (RER in clinically diagnosed pellagra patients. Materials and methods: Clinically diagnosed pellagra patients aged between 18 to 40 years, both male and females were recruited (n=78 from department of Dermatology. Age and gender matched controls (n=78 were recruited from the student and residents of the hospital. Malondialdehyde (MDA is a marker of lipid peroxidation, Total Anti Oxidant Status (TAOS and Redox Ratio (RER markers were assessed by using commercially available kits. Results: There were no significant differences in the anthropometric parameters. However, the oxidative stress markers MDA (p<0.05, RER (p<0.001 were significantly high and TAOS was low (P<0.001 in pellagra patients in comparison with age and gender matched controls. Conclusion: The results of this study showed the increased MDA, RER levels and decreased TAOS levels. Estimation of these markers at early stage will help to take measures to prevent the progression of disease and develop antioxidant strategies.

  6. Oxidation and erosion-oxidation behavior of steels

    Directory of Open Access Journals (Sweden)

    Stela Maria de Carvalho Fernandes

    2008-03-01

    Full Text Available The high temperature oxidation and erosion-oxidation (E-O behavior of steels AISI 1020, 304, 310, and 410 were determined. These steels were selected to evaluate the effect of chromium content on its E-O resistance. The oxidation behavior was determined in a thermogravimetric analyzer. A test rig in which a specimen assembly was rotated through a fluidized bed of erodent particles was used to determine the E-O behavior. Alumina powder (200 µm was used as the erodent. The E-O tests were carried out in the temperature range 25-600 °C, with average particle impact velocities of 3.5 and 15 ms-1 and impact angle of 90°. The oxidation resistance of the steels increased with chromium content. The E-O behavior of the steels was determined as wastage. The E-O wastage of the steels exposed to particle impact at low velocity was low but increased with temperature above 300 °C. The E-O wastage of the different steels exposed to particle impact at high velocity was quite similar. The wastage increased with increase in temperature above 500 °C. The increases in E-O wastage of the steels observed at temperatures above 300, 400 or 500 °C, depending on the steel, were due mainly to a transition in the dominant wastage process, from 'erosion' to 'erosion-oxidation'.

  7. Nitroxide-Functionalized Graphene Oxide from Graphite Oxide.

    Science.gov (United States)

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

    2013-11-01

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

  8. Chemical oxidative polymerization of aminodiphenylamines.

    Science.gov (United States)

    Cirić-Marjanović, Gordana; Trchová, Miroslava; Konyushenko, Elena N; Holler, Petr; Stejskal, Jaroslav

    2008-06-12

    The course of oxidation of 4-aminodiphenylamine with ammonium peroxydisulfate in an acidic aqueous ethanol solution as well as the properties of the oxidation products were compared with those of 2-aminodiphenylamine. Semiconducting oligomers of 4-aminodiphenylamine and nonconducting oligomers of 2-aminodiphenylamine of weight-average molecular weights 3700 and 1900, respectively, were prepared by using an oxidant to monomer molar ratio of 1.25. When this ratio was changed from 0.5 to 2.5, the highest conductivity of oxidation products of 4-aminodiphenylamine, 2.5 x 10 (-4) S cm (-1), was reached at the molar ratio [oxidant]/[monomer] = 1.5. The mechanism of the oxidative polymerization of aminodiphenylamines has been theoretically studied by the AM1 and MNDO-PM3 semiempirical quantum chemical methods combined with the MM2 molecular mechanics force-field method and conductor-like screening model of solvation. Molecular orbital calculations revealed the prevalence of N prim-C10 coupling reaction of 4-aminodiphenylamine, while N prim-C5 is the main coupling mode between 2-aminodiphenylamine units. FTIR and Raman spectroscopic studies confirm the prevalent formation of linear N prim-C10 coupled oligomers of 4-aminodiphenylamine and suggest branching and formation of phenazine structural units in the oligomers of 2-aminodiphenylamine. The results are discussed with respect to the oxidation of aniline with ammonium peroxydisulfate, leading to polyaniline, in which 4-aminodiphenylamine is the major dimer and 2-aminodiphenylamine is the most important dimeric intermediate byproduct.

  9. Mesoporous metal oxide graphene nanocomposite materials

    Science.gov (United States)

    Liu, Jun; Aksay, Ilhan A.; Kou, Rong; Wang, Donghai

    2016-05-24

    A nanocomposite material formed of graphene and a mesoporous metal oxide having a demonstrated specific capacity of more than 200 F/g with particular utility when employed in supercapacitor applications. A method for making these nanocomposite materials by first forming a mixture of graphene, a surfactant, and a metal oxide precursor, precipitating the metal oxide precursor with the surfactant from the mixture to form a mesoporous metal oxide. The mesoporous metal oxide is then deposited onto a surface of the graphene.

  10. Graphene-supported metal oxide monolith

    Science.gov (United States)

    Worsley, Marcus A.; Baumann, Theodore F.; Biener, Juergen; Biener, Monika A.; Wang, Yinmin; Ye, Jianchao; Tylski, Elijah

    2017-01-10

    A composition comprising at least one graphene-supported metal oxide monolith, said monolith comprising a three-dimensional structure of graphene sheets crosslinked by covalent carbon bonds, wherein the graphene sheets are coated by at least one metal oxide such as iron oxide or titanium oxide. Also provided is an electrode comprising the aforementioned graphene-supported metal oxide monolith, wherein the electrode can be substantially free of any carbon-black and substantially free of any binder.

  11. Is the Oxidative Stress Really a Disease?

    OpenAIRE

    Fogarasi Erzsébet; Croitoru Mircea Dumitru; Fülöp Ibolya; Muntean Daniela-Lucia

    2016-01-01

    Oxidative stress is an imbalance between free radicals or other reactive species and the antioxidant activity of the organism. Oxidative stress can induce several illnesses such as cardiovascular disease, neurodegenerative disorders, diabetes, cancer, Alzheimer and Parkinson. The biomarkers of oxidative stress are used to test oxidative injury of biomolecules. The indicators of lipid peroxidation (malondialdehyde, 4-hydroxy- 2-nonenal, 2-propenal, isoprostanes), of protein oxidation (carbonyl...

  12. Oxidative stress in Parkinson’s disease

    OpenAIRE

    Nikam, Shashikant; Nikam, Padmaja; Ahaley, S. K.; Sontakke, Ajit V.

    2009-01-01

    Oxidative stress contributes to the cascade, leading to dopamine cell degeneration in Parkinson’s disease. However, oxidative stress is intimately linked to other components of the degenerative process, such as mitochondrial dysfunction, excitotoxicity, nitric oxide toxicity and inflammation. It is therefore difficult to determine whether oxidative stress leads to or is a consequence of, these events. Oxidative stress was assessed by estimating lipid peroxidation product in the form of thioba...

  13. 21 CFR 186.1374 - Iron oxides.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Iron oxides. 186.1374 Section 186.1374 Food and... Substances Affirmed as GRAS § 186.1374 Iron oxides. (a) Iron oxides (oxides of iron, CAS Reg. No. 1332-37-2) are undefined mixtures of iron (II) oxide (CAS Reg. No. 1345-25-1, black cubic crystals) and iron (III...

  14. Transparent conducting oxides and production thereof

    Science.gov (United States)

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

    2014-05-27

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

  15. Wet-cupping removes oxidants and decreases oxidative stress.

    Science.gov (United States)

    Tagil, Suleyman Murat; Celik, Huseyin Tugrul; Ciftci, Sefa; Kazanci, Fatmanur Hacievliyagil; Arslan, Muzeyyen; Erdamar, Nazan; Kesik, Yunus; Erdamar, Husamettin; Dane, Senol

    2014-12-01

    Wet-cupping therapy is one of the oldest known medical techniques. Although it is widely used in various conditions such as acute\\chronic inflammation, infectious diseases, and immune system disorders, its mechanism of action is not fully known. In this study, we investigated the oxidative status as the first step to elucidate possible mechanisms of action of wet cupping. Wet cupping therapy is implemented to 31 healthy volunteers. Venous blood samples and Wet cupping blood samples were taken concurrently. Serum nitricoxide, malondialdehyde levels and activity of superoxide dismutase and myeloperoxidase were measured spectrophotometrically. Wet cupping blood had higher activity of myeloperoxidase, lower activity of superoxide dismutase, higher levels of malondialdehyde and nitricoxide compared to the venous blood. Wet cupping removes oxidants and decreases oxidative stress. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Metal oxide nanorod arrays on monolithic substrates

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Pu-Xian; Guo, Yanbing; Ren, Zheng

    2018-01-02

    A metal oxide nanorod array structure according to embodiments disclosed herein includes a monolithic substrate having a surface and multiple channels, an interface layer bonded to the surface of the substrate, and a metal oxide nanorod array coupled to the substrate surface via the interface layer. The metal oxide can include ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide. The substrate can include a glass substrate, a plastic substrate, a silicon substrate, a ceramic monolith, and a stainless steel monolith. The ceramic can include cordierite, alumina, tin oxide, and titania. The nanorod array structure can include a perovskite shell, such as a lanthanum-based transition metal oxide, or a metal oxide shell, such as ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide, or a coating of metal particles, such as platinum, gold, palladium, rhodium, and ruthenium, over each metal oxide nanorod. Structures can be bonded to the surface of a substrate and resist erosion if exposed to high velocity flow rates.

  17. Heterogeneous Partial (ammOxidation and Oxidative Dehydrogenation Catalysis on Mixed Metal Oxides

    Directory of Open Access Journals (Sweden)

    Jacques C. Védrine

    2016-01-01

    Full Text Available This paper presents an overview of heterogeneous partial (ammoxidation and oxidative dehydrogenation (ODH of hydrocarbons. The review has been voluntarily restricted to metal oxide-type catalysts, as the partial oxidation field is very broad and the number of catalysts is quite high. The main factors of solid catalysts for such reactions, designated by Grasselli as the “seven pillars”, and playing a determining role in catalytic properties, are considered to be, namely: isolation of active sites (known to be composed of ensembles of atoms, Me–O bond strength, crystalline structure, redox features, phase cooperation, multi-functionality and the nature of the surface oxygen species. Other important features and physical and chemical properties of solid catalysts, more or less related to the seven pillars, are also emphasized, including reaction sensitivity to metal oxide structure, epitaxial contact between an active phase and a second phase or its support, synergy effect between several phases, acid-base aspects, electron transfer ability, catalyst preparation and activation and reaction atmospheres, etc. Some examples are presented to illustrate the importance of these key factors. They include light alkanes (C1–C4 oxidation, ethane oxidation to ethylene and acetic acid on MoVTe(SbNb-O and Nb doped NiO, propene oxidation to acrolein on BiMoCoFe-O systems, propane (ammoxidation to (acrylonitrile acrylic acid on MoVTe(SbNb-O mixed oxides, butane oxidation to maleic anhydride on VPO: (VO2P2O7-based catalyst, and isobutyric acid ODH to methacrylic acid on Fe hydroxyl phosphates. It is shown that active sites are composed of ensembles of atoms whose size and chemical composition depend on the reactants to be transformed (their chemical and size features and the reaction mechanism, often of Mars and van Krevelen type. An important aspect is the fact that surface composition and surface crystalline structure vary with reaction on stream until

  18. Solid oxide electrochemical reactor science.

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-09-01

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

  19. Oxidative stress and diabetes mellitus.

    Science.gov (United States)

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

    2011-11-01

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

  20. Absorption and oxidation of nitrogen oxide in ionic liquids

    DEFF Research Database (Denmark)

    Kunov-Kruse, Andreas Jonas; Thomassen, Peter Langelund; Riisager, Anders

    2016-01-01

    A new strategy for capturing nitrogen oxide, NO, from the gas phase is presented. Dilute NO gas is removed from the gas phase by ionic liquids under ambient conditions. The nitrate anion of the ionic liquid catalyzes the oxidation of NO to nitric acid by atmospheric oxygen in the presence of water...... investigations of the reaction and products are presented. The procedure reveals a new vision for removing the pollutant NO by absorption into a non-volatile liquid and converting it into a useful bulk chemical, that is, HNO3....

  1. Thermal oxidation and electrical properties of silicon carbide metal-oxide-semiconductor structures

    Science.gov (United States)

    Singh, N.; Rys, A.

    1993-02-01

    The fabrication of metal-oxide-semiconductor (MOS) capacitors on n-type, Si-face 6H-SiC is described for both wet and dry oxidation processes, and the effect of thermal oxidation conditions on the electrical properties of MOS capacitors are investigated. The values of the oxide thickness were obtained as a function of the oxidation time at various oxidation temperatures (which were kept between 1150 and 1250 C). It was found that samples prepared by both dry and wet oxidation showed accumulation, depletion, and inversion regions under illumination, while inversion did not occur under dark conditions. The C-V characteristics of oxidized samples were improved after the oxidized samples were annealed in argon for 30 min. The relation between the oxide thickness and the oxidation time could be expressed by parabolic law, which is also used for thermal oxidation of Si.

  2. Reduced graphene oxide molecular sensors.

    Science.gov (United States)

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

    2008-10-01

    We demonstrate reduced graphene oxide as the active material for high-performance molecular sensors. Sensors are fabricated from exfoliated graphene oxide platelets that are deposited to form an ultrathin continuous network. These graphene oxide networks are tunably reduced toward graphene by varying the exposure time to a hydrazine hydrate vapor. The conductance change of the networks upon exposure to trace levels of vapor is measured as a function of the chemical reduction. The level of reduction affects both the sensitivity and the level of 1/ f noise. The sensors are capable of detecting 10 s exposures to simulants of the three main classes of chemical-warfare agents and an explosive at parts-per-billion concentrations.

  3. Atmospheric oxidation of selected hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Benter, T.; Olariu, R.I.

    2002-02-01

    This work presents investigations on the gas-phase chemistry of phenol and the cresol isomers performed in a 1080 l quartz glass reactor in Wuppertal and in a large-volume outdoor photoreactor EUPHORE in Valencia, Spain. The studies aimed at clarifying the oxidation mechanisms of the reactions of these compounds with OH and NO{sub 3} radicals. Product investigations on the oxidation of phenol and the cresol isomers initiated by OH radicals were performed in the 1080 l quartz glass reactor with analyses by in situ FT-IR absorption spectroscopy. The primary focus of the investigations was on the determination of product yields. This work represents the first determination and quantification of 1,2-dihydroxybenzenes in the OH oxidation of phenolic compounds. Possible reaction pathways leading to the observed products have been elucidated. (orig.)

  4. CELLULOSE DEGRADATION BY OXIDATIVE ENZYMES

    Directory of Open Access Journals (Sweden)

    Maria Dimarogona

    2012-09-01

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

  5. Cellulose degradation by oxidative enzymes

    Directory of Open Access Journals (Sweden)

    Maria Dimarogona

    2012-09-01

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

  6. Resveratrol and Endothelial Nitric Oxide

    Directory of Open Access Journals (Sweden)

    Ning Xia

    2014-10-01

    Full Text Available Nitric oxide (NO derived from the endothelial NO synthase (eNOS has antihypertensive, antithrombotic, anti-atherosclerotic and antiobesogenic properties. Resveratrol is a polyphenol phytoalexin with multiple cardiovascular and metabolic effects. Part of the beneficial effects of resveratrol are mediated by eNOS. Resveratrol stimulates NO production from eNOS by a number of mechanisms, including upregulation of eNOS expression, stimulation of eNOS enzymatic activity and reversal of eNOS uncoupling. In addition, by reducing oxidative stress, resveratrol prevents oxidative NO inactivation by superoxide thereby enhancing NO bioavailability. Molecular pathways underlying these effects of resveratrol involve SIRT1, AMPK, Nrf2 and estrogen receptors.

  7. Oxidative pyrolysis of solid fuels

    Energy Technology Data Exchange (ETDEWEB)

    Senneca, Osvalda; Chirone, Riccardo [Istituto di Ricerche sulla Combustione, C.N.R., P.le Tecchio 80, 80125 Napoli (Italy); Salatino, Piero [Dipartimento di Ingegneria Chimica, Universita degli Studi di Napoli Federico II, P.le Tecchio 80, 80125 Napoli (Italy)

    2004-06-01

    This study addresses the dependence of the rate and pattern of pyrolysis of solid fuels from the oxidizing versus inert nature of the gaseous atmosphere. A selection of four solid fuels is considered in the study, namely two plastics (polyethylene and polyethylene terephthalate), one lignocellulosic material (Robinia Pseudoacacia) and a South African bituminous coal. Fuels are pyrolyzed in a thermogravimetric apparatus at different heating rates, under inert conditions or in the presence of oxygen at different concentration.Results indicate that the action exerted by oxygen during pyrolysis depends on the nature of the fuel and on the process conditions such as heating rate and oxygen concentration. Larger heating rates and larger oxygen concentration may indeed emphasize differences between inert and oxidative pyrolysis. Further analysis is directed to check the adequacy of a power low kinetic expression to describe the dependence of the rate of oxidative pyrolysis from the level of oxygen concentration.

  8. Oxide Fiber Targets at ISOLDE

    CERN Document Server

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

    2003-01-01

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

  9. Graphite Oxidation Thermodynamics/Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Propp, W.A.

    1998-09-01

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

  10. Atomistic stimulation of defective oxides

    CERN Document Server

    Minervini, L

    2000-01-01

    defect processes. The predominant intrinsic disorder reaction and the mechanism by which excess oxygen is accommodated are established. Furthermore, the most favourable migration mechanism and pathway for oxygen ions is predicted. Chapters 7 and 8 investigate pyrochlore oxides. These materials are candidates for solid oxide fuel cell components and as actinide host phases. Such applications require a detailed understanding of the defect processes. The defect energies, displayed as contour maps, are able to account for structure stability and, given an appropriate partial charge potential model, to accurately determine the oxygen positional parameter. In particular, the dependence of the positional parameter on intrinsic disorder is predicted. It is demonstrated, by radiation damage experiments, that these results are able to predict the radiation performance of pyrochlore oxides. Atomistic simulation calculations based on energy minimization techniques and classical pair potentials are used to study several i...

  11. Cardiopulmonary Bypass and Oxidative Stress

    Science.gov (United States)

    Zakkar, Mustafa; Guida, Gustavo; Suleiman, M-Saadeh; Angelini, Gianni D.

    2015-01-01

    The development of the cardiopulmonary bypass (CPB) revolutionized cardiac surgery and contributed immensely to improved patients outcomes. CPB is associated with the activation of different coagulation, proinflammatory, survival cascades and altered redox state. Haemolysis, ischaemia, and perfusion injury and neutrophils activation during CPB play a pivotal role in oxidative stress and the associated activation of proinflammatory and proapoptotic signalling pathways which can affect the function and recovery of multiple organs such as the myocardium, lungs, and kidneys and influence clinical outcomes. The administration of agents with antioxidant properties during surgery either intravenously or in the cardioplegia solution may reduce ROS burst and oxidative stress during CPB. Alternatively, the use of modified circuits such as minibypass can modify both proinflammatory responses and oxidative stress. PMID:25722792

  12. Oxidative Reactions with Nonaqueous Enzymes

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-12-30

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

  13. Aromatic-radical oxidation chemistry

    Energy Technology Data Exchange (ETDEWEB)

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

    1993-12-01

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

  14. Study of nitric oxide catalytic oxidation on manganese oxides-loaded activated carbon at low temperature

    Science.gov (United States)

    You, Fu-Tian; Yu, Guang-Wei; Wang, Yin; Xing, Zhen-Jiao; Liu, Xue-Jiao; Li, Jie

    2017-08-01

    Nitric oxide (NO) is an air pollutant that is difficult to remove at low concentration and low temperature. Manganese oxides (MnOx)-loaded activated carbon (MLAC) was prepared by a co-precipitation method and studied as a new catalyst for NO oxidation at low temperature. Characterization of MLAC included X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 adsorption/desorption and X-ray photoelectron spectroscopy (XPS). Activity tests demonstrated the influence of the amount of MnOx and the test conditions on the reaction. MLAC with 7.5 wt.% MnOx (MLAC003) exhibits the highest NO conversion (38.7%) at 1000 ppm NO, 20 vol.% O2, room temperature and GHSV ca. 16000 h-1. The NO conversion of MLAC003 was elevated by 26% compared with that of activated carbon. The results of the MLAC003 activity test under different test conditions demonstrated that NO conversion is also influenced by inlet NO concentration, inlet O2 concentration, reaction temperature and GHSV. The NO adsorption-desorption process in micropores of activated carbon is fundamental to NO oxidation, which can be controlled by pore structure and reaction temperature. The activity elevation caused by MnOx loading is assumed to be related to Mn4+/Mn3+ ratio. Finally, a mechanism of NO catalytic oxidation on MLAC based on NO adsorption-desorption and MnOx lattice O transfer is proposed.

  15. Controlled oxidation of graphite to graphene oxide with novel oxidants in a bulk scale.

    Science.gov (United States)

    Wojtoniszak, Malgorzata; Mijowska, Ewa

    2012-11-01

    In this study, a novel method of graphite chemical exfoliation to create graphene oxide (GO) is reported. Here, new oxidants were examined: a mixture of perchloric and nitric acids and potassium chromate. Furthermore, an effect of oxidation time, temperature of oxidation, and ultrasonication on graphite exfoliation degree was investigated. The obtained GOs were next reduced with glucose, used as a reducing agent. Detailed analysis of the materials indicated that when graphite was oxidized for 24 h at 50 °C, 5-layered graphene was prepared. An effect of sonication process was also examined, and it was found to enhance the exfoliation to bilayer graphene. Furthermore, when time and temperature were increased to 48 h and 100 °C, respectively, graphite was exfoliated to single-layer graphene. Therefore, it is believed that the proposed route can be applied for the preparation of graphene or few-layered graphene with defined number of layers upon the process parameters optimization and in a bulk scale. The materials were characterized with atomic force microscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, and X-ray diffraction.

  16. Zinc oxide doped graphene oxide films for gas sensing applications

    Energy Technology Data Exchange (ETDEWEB)

    Chetna,, E-mail: chetna2288@gmail.com; Kumar, Shani; Chaudhary, S.; Kapoor, A. [Department of Electronic Science, University of Delhi South Campus, Benito Juarez Road, New Delhi-110021 (India); Garg, A.; Chowdhuri, A.; Dhingra, V. [Department of Electronic Science, Acharya Narendra Dev College, University of Delhi, Kalkaji, New Delhi- 110019 (India)

    2016-05-06

    Graphene Oxide (GO) is analogous to graphene, but presence of many functional groups makes its physical and chemical properties essentially different from those of graphene. GO is found to be a promising material for low cost fabrication of highly versatile and environment friendly gas sensors. Selectivity, reversibility and sensitivity of GO based gas sensor have been improved by hybridization with Zinc Oxide nanoparticles. The device is fabricated by spin coating of deionized water dispersed GO flakes (synthesized using traditional hummer’s method) doped with Zinc Oxide on standard glass substrate. Since GO is an insulator and functional groups on GO nanosheets play vital role in adsorbing gas molecules, it is being used as an adsorber. Additionally, on being exposed to certain gases the electric and optical characteristics of GO material exhibit an alteration in behavior. For the conductivity, we use Zinc Oxide, as it displays a high sensitivity towards conduction. The effects of the compositions, structural defects and morphologies of graphene based sensing layers and the configurations of sensing devices on the performances of gas sensors were investigated by Raman Spectroscopy, X-ray diffraction(XRD) and Keithley Sourcemeter.

  17. Supported versus colloidal zinc oxide for advanced oxidation processes

    Science.gov (United States)

    Laxman, Karthik; Al Rashdi, Manal; Al Sabahi, Jamal; Al Abri, Mohammed; Dutta, Joydeep

    2017-07-01

    Photocatalysis is a green technology which typically utilizes either supported or colloidal catalysts for the mineralization of aqueous organic contaminants. Catalyst surface area and surface energy are the primary factors determining its efficiency, but correlation between the two is still unclear. This work explores their relation and hierarchy in a photocatalytic process involving both supported and colloidal catalysts. In order to do this the active surface areas of supported zinc oxide nanorods (ZnO NR's) and colloidal zinc oxide nanoparticles (having different surface energies) were equalized and their phenol oxidation mechanism and capacity was analyzed. It was observed that while surface energy had subtle effects on the oxidation rate of the catalysts, the degradation efficiency was primarily a function of the surface area; which makes it a better parameter for comparison when studying different catalyst forms of the same material. Thus we build a case for the use of supported catalysts, wherein their catalytic efficiency was tested to be unaltered over several days under both natural and artificial light, suggesting their viability for practical applications.

  18. Oxidation mechanisms for alloys in single-oxidant gases

    Energy Technology Data Exchange (ETDEWEB)

    Whittle, D.P.

    1981-03-01

    Scales formed on alloys invariably contain the alloy constituents in a ratio different from that in the alloy, owing to the differing thermodynamic tendencies of the alloy components to react with the oxidant and to differences in diffusion rates in scale and alloy phases. This complex interrelationship between transport rates and the thermodynamics of the alloy-oxidant system can be analyzed using multicomponent diffusion theory when transport-controlled growth of single or multi-layered scales occurs. In particular, the superimposition of the diffusion data on an isothermal section of the appropriate phase diagram indicates the likely morphologies of the reaction products, including the sequence of phases found in the scale, the occurrence of internal oxidation and the development of an irregular metal/scale interface. The scale morphologies on alloys are also time-dependent: there is an initial transient stage, a steady state period, and a final breakdown, the latter often related to mechanical influences such as scale adherence, spallation, thermal or mechanical stresses and void formation. Mechanical influences have a more devastating effect in alloy oxidation due to the changes in alloy surface composition during the steady state period.

  19. Oxidative stress inhibition and oxidant activity by fibrous clays.

    Science.gov (United States)

    Cervini-Silva, Javiera; Nieto-Camacho, Antonio; Gómez-Vidales, Virginia

    2015-09-01

    Fibrous clays (sepiolite, palygorskite) are produced at 1.2m tonnes per year and have a wide range of industrial applications needing to replace long-fibre length asbestos. However, information on the beneficial effects of fibrous clays on health remains scarce. This paper reports on the effect of sepiolite (Vallecas, Spain) and palygorskite (Torrejón El Rubio, Spain) on cell damage via oxidative stress (determined as the progress of lipid peroxidation, LP). The extent of LP was assessed using the Thiobarbituric Acid Reactive Substances assay. The oxidant activity by fibrous clays was quantified using Electron-Paramagnetic Resonance. Sepiolite and palygorskite inhibited LP, whereby corresponding IC50 values were 6557±1024 and 4250±289μgmL(-1). As evidenced by dose-response experiments LP inhibition by palygorskite was surface-controlled. Fibrous clay surfaces did not stabilize HO species, except for suspensions containing 5000μgmL(-1). A strong oxidant (or weak anti-oxidant) activity favours the inhibition of LP by fibrous clays. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Diabetes, oxidative stress, nitric oxide and mitochondria function.

    Science.gov (United States)

    Friederich, Malou; Hansell, Peter; Palm, Fredrik

    2009-05-01

    The role of altered mitochondria function has recently emerged as an important mechanism for the development of diabetic complications. Altered mitochondria function has also been implicated in the ageing process, defective insulin secretion, hypertension, arteriosclerosis, ischemia-reperfusion injury and apoptosis. Normally, the mitochondria are associated with ATP production using primarily pyruvate as the substrate, but recent reports indicate that tissue specific preferences exist. Also, the mitochondria are a substantial source of superoxide production, preferentially during states of elevated intracellular glucose concentrations. The mitochondria function is regulated by several factors including nitric oxide, oxidative stress, mammalian target of rapamycin, ADP and P(i) availability, which result in a complex regulation of ATP production and oxygen consumption, but also superoxide generation. These factors seem to be tissue specific, which warrants a more diverse mechanistic model applying to that specific tissue or cell type. This review presents the basic functions of the mitochondria and focuses on the complex interplay between oxidative stress, nitric oxide and uncoupling proteins in regulating mitochondria function with special focus on diabetes-induced alterations occurring on the mitochondria level.

  1. Synthesis of Ordered Mesoporous Manganese Oxides with Various Oxidation States.

    Science.gov (United States)

    Park, Gwi Ok; Shon, Jeong Kuk; Kim, Yong Ho; Kim, Ji Man

    2015-03-01

    Ordered mesoporous MnO, MnO4, Mn2O3 and MnO2 materials with 3-D pore structure were suc- cessfully synthesized via a nano-replication method by using ordered mesoporous silica, KIT-6 (Cubic Ia3d space group mesostructure) as the template under specific oxidation and reduction conditions. Notably, ordered mesoporous MnO with a crystalline wall (rock salt structure) was syn- thesized for the first time, to the best of our knowledge. The synthesis of the ordered mesoporous MnO was achieved by reducing the ordered mesoporous Mn3O4 under an H2 atmosphere, while preserving the ordered mesostructure and crystalline wall throughout the solid/solid transformation. All of the ordered mesoporous manganese oxides with different crystal structures and oxidation states demonstrated almost the same spherical-like morphology with several hundred nanometers of particles. The synthesized ordered mesoporous manganese oxides had uniform dual mesopores (2-3 nm, and ~20 nm) and crystalline frameworks with large surface areas (86-140 m2/g) and pore volumes (0.27-0.33 cm3/g).

  2. Graphene oxide and H2 production from bioelectrochemical graphite oxidation.

    Science.gov (United States)

    Lu, Lu; Zeng, Cuiping; Wang, Luda; Yin, Xiaobo; Jin, Song; Lu, Anhuai; Jason Ren, Zhiyong

    2015-11-17

    Graphene oxide (GO) is an emerging material for energy and environmental applications, but it has been primarily produced using chemical processes involving high energy consumption and hazardous chemicals. In this study, we reported a new bioelectrochemical method to produce GO from graphite under ambient conditions without chemical amendments, value-added organic compounds and high rate H2 were also produced. Compared with abiotic electrochemical electrolysis control, the microbial assisted graphite oxidation produced high rate of graphite oxide and graphene oxide (BEGO) sheets, CO2, and current at lower applied voltage. The resultant electrons are transferred to a biocathode, where H2 and organic compounds are produced by microbial reduction of protons and CO2, respectively, a process known as microbial electrosynthesis (MES). Pseudomonas is the dominant population on the anode, while abundant anaerobic solvent-producing bacteria Clostridium carboxidivorans is likely responsible for electrosynthesis on the cathode. Oxygen production through water electrolysis was not detected on the anode due to the presence of facultative and aerobic bacteria as O2 sinkers. This new method provides a sustainable route for producing graphene materials and renewable H2 at low cost, and it may stimulate a new area of research in MES.

  3. Oxidation kinetics of Si and SiGe by dry rapid thermal oxidation, in-situ steam generation oxidation and dry furnace oxidation

    Science.gov (United States)

    Rozé, Fabien; Gourhant, Olivier; Blanquet, Elisabeth; Bertin, François; Juhel, Marc; Abbate, Francesco; Pribat, Clément; Duru, Romain

    2017-06-01

    The fabrication of ultrathin compressively strained SiGe-On-Insulator layers by the condensation technique is likely a key milestone towards low-power and high performances FD-SOI logic devices. However, the SiGe condensation technique still requires challenges to be solved for an optimized use in an industrial environment. SiGe oxidation kinetics, upon which the condensation technique is founded, has still not reached a consensus in spite of various studies which gave insights into the matter. This paper aims to bridge the gaps between these studies by covering various oxidation processes relevant to today's technological needs with a new and quantitative analysis methodology. We thus address oxidation kinetics of SiGe with three Ge concentrations (0%, 10%, and 30%) by means of dry rapid thermal oxidation, in-situ steam generation oxidation, and dry furnace oxidation. Oxide thicknesses in the 50 Å to 150 Å range grown with oxidation temperatures between 850 and 1100 °C were targeted. The present work shows first that for all investigated processes, oxidation follows a parabolic regime even for thin oxides, which indicates a diffusion-limited oxidation regime. We also observe that, for all investigated processes, the SiGe oxidation rate is systematically higher than that of Si. The amplitude of the variation of oxidation kinetics of SiGe with respect to Si is found to be strongly dependent on the process type. Second, a new quantitative analysis methodology of oxidation kinetics is introduced. This methodology allows us to highlight the dependence of oxidation kinetics on the Ge concentration at the oxidation interface, which is modulated by the pile-up mechanism. Our results show that the oxidation rate increases with the Ge concentration at the oxidation interface.

  4. New quinoproteins in oxidative fermentation.

    Science.gov (United States)

    Adachi, O; Moonmangmee, D; Shinagawa, E; Toyama, H; Yamada, M; Matsushita, K

    2003-04-11

    Several quinoproteins have been newly indicated in acetic acid bacteria, all of which can be applied to fermentative or enzymatic production of useful materials by means of oxidative fermentation. (1) D-Arabitol dehydrogenase from Gluconobacter suboxydans IFO 3257 was purified from the bacterial membrane and found to be a versatile enzyme for oxidation of various substrates to the corresponding oxidation products. It is worthy of notice that the enzyme catalyzes D-gluconate oxidation to 5-keto-D-gluconate, whereas 2-keto-D-gluconate is produced by a flavoprotein D-gluconate dehydrogenase. (2) Membrane-bound cyclic alcohol dehydrogenase was solubilized and purified for the first time from Gluconobacter frateurii CHM 9. When compared with the cytosolic NAD-dependent cyclic alcohol dehydrogenase crystallized from the same strain, the reaction rate in cyclic alcohol oxidation by the membrane enzyme was 100 times stronger than the cytosolic NAD-dependent enzyme. The NAD-dependent enzyme makes no contribution to cyclic alcohol oxidation but contributes to the reduction of cyclic ketones to cyclic alcohols. (3) Meso-erythritol dehydrogenase has been purified from the membrane fraction of G. frateurii CHM 43. The typical properties of quinoproteins were indicated in many respects with the enzyme. It was found that the enzyme, growing cells and also the resting cells of the organism are very effective in producing L-erythrulose. Dihydroxyacetone can be replaced by L-erythrulose for cosmetics for those who are sensitive to dihydroxyacetone. (4) Two different membrane-bound D-sorbitol dehydrogenases were indicated in acetic acid bacteria. One enzyme contributing to L-sorbose production has been identified to be a quinoprotein, while another FAD-containing D-sorbitol dehydrogenase catalyzes D-sorbitol oxidation to D-fructose. D-Fructose production by the oxidative fermentation would be possible by the latter enzyme and it is superior to the well-established D-glucose isomerase

  5. Characterization and reactivity of biogenic manganese oxides for ciprofloxacin oxidation.

    Science.gov (United States)

    Tu, Jinjun; Yang, Zhendong; Hu, Chun; Qu, Jiuhui

    2014-05-01

    Biogenic manganese oxides (BioMnOx) were synthesized by the oxidation of Mn(II) with Mn-oxidizing bacteria Pseudomonas sp. G7 under different initial pH values and Mn(II) dosages, and were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and UV-Vis absorption spectroscopy. The crystal structure and Mn oxidation states of BioMnOx depended on the initial pH and Mn(II) dosages of the medium. The superoxide radical (O(·-)2) was observed in Mn-containing (III/IV) BioMnOx suspensions by electron spin resonance measurements. BioMnOx(0.4)-7, with mixed valence of Mn(II/III/IV) and the strongest O(·-)2 signals, was prepared in the initial pH 7 and Mn(II) dosage of 0.4 mmol/L condition, and exhibited the highest activity for ciprofloxacin degradation and no Mn(II) release. During the degradation of ciprofloxacin, the oxidation of the Mn(II) formed came from biotic and abiotic reactions in BioMnOx suspensions on the basis of the Mn(II) release and O(·-)2 formation from different BioMnOx. The degradation process of ciprofloxacin was shown to involve the cleavage of the hexatomic ring having a secondary amine and carbon-carbon double bond connected to a carboxyl group, producing several compounds containing amine groups as well as small organic acids. Copyright © 2014 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  6. Oxidation of pyrite: Consequences and significance

    Directory of Open Access Journals (Sweden)

    Dimitrijević Mile D.

    2002-01-01

    Full Text Available This paper presents the most important studies on the oxidation of pyrite particularly in aqueous solutions. The consequences of pyrite oxidation was examined, as well as its importance, from both the technical-technological and environmental points of view. The oxidation of pyrite was considered in two parts. The spontaneous oxidation of pyrite in nature was described in the first part, with this part comprising pyrite oxidation in deposits depots and mines. It is explained how way natural electrochemical processes lead to the decomposition of pyrite and other minerals associated with pyrite. The oxidation of pyrite occurring during technological processes such as grinding, flotation and leaching, was shown in the second part. Particular emphasis was placed on the oxidation of pyrite during leaching. This part includes the leaching of sulphide and oxide ores, the leaching of pyrite coal and the leaching of refractory gold-bearing ores (pressure oxidation, bacterial oxidation, oxidation by means of strong oxidants and the electrolysis of pyrite suspensions. Various mechanisms of pyrite oxidation and of the galvanic interaction of pyrite with other sulphide minerals are shown.

  7. Growth of zinc oxide nanostructures

    Indian Academy of Sciences (India)

    and nanoparticle ZnO films on glass substrate were also prepared by a chemical route. Nanowhiskers showed ... prepared ZnO nanoparticle films exhibited good sensing properties for alcohol. Keywords. Zinc oxide .... and the solution was used to deposit a film by spin coating on a glass substrate. The deposited film was ...

  8. Oxidation events and skin aging

    NARCIS (Netherlands)

    Kammeyer, A.; Luiten, R. M.

    2015-01-01

    The rate of skin aging, or that of tissue in general, is determined by a variable predominance of tissue degeneration over tissue regeneration. This review discusses the role of oxidative events of tissue degeneration and aging in general, and for the skin in particular. The mechanisms involved in

  9. Radiation annealing in cuprous oxide

    DEFF Research Database (Denmark)

    Vajda, P.

    1966-01-01

    Experimental results from high-intensity gamma-irradiation of cuprous oxide are used to investigate the annealing of defects with increasing radiation dose. The results are analysed on the basis of the Balarin and Hauser (1965) statistical model of radiation annealing, giving a square...

  10. Exciton dynamics in cuprous oxide

    NARCIS (Netherlands)

    Fishman, D. A.; Revcolevschi, A.; van Loosdrecht, P. H. M.; Stutzmann, M

    2006-01-01

    This work addresses the mid-infrared properties of cuprous oxide and in particular induced absorption due to the presence of excitons. We probe the population of the non-radiative ground state of para-excitons via laser-induced changes of the transmission in the "hydrogenic" 1s-2p/1s-3p transition

  11. on THICKNESS OF COPPER (|) OXIDE

    African Journals Online (AJOL)

    2006-12-20

    Dec 20, 2006 ... Observed to be an attractive starting material for the production of solar cells for low cost terrestrial conversion of solar energy to electricity. Copper (I) oxide is one Of the earliest known photovoltaic materials and the first in which the photovOltaic effect was successfully explained (Fortin and Sears,. 1981).

  12. COPD: balancing oxidants and antioxidants

    Directory of Open Access Journals (Sweden)

    Fischer BM

    2015-02-01

    Full Text Available Bernard M Fischer,1,* Judith A Voynow,2,* Andrew J Ghio3,* 1Department of Pediatrics, Duke University Medical Center, Durham, NC, USA; 2Department of Pediatrics, Children's Hospital of Richmond at Virginia Commonwealth University, Richmond, VA, USA; 3National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Chapel Hill, NC, USA *These authors contributed equally to this work Abstract: Chronic obstructive pulmonary disease (COPD is one of the most common chronic illnesses in the world. The disease encompasses emphysema, chronic bronchitis, and small airway obstruction and can be caused by environmental exposures, primarily cigarette smoking. Since only a small subset of smokers develop COPD, it is believed that host factors interact with the environment to increase the propensity to develop disease. The major pathogenic factors causing disease include infection and inflammation, protease and antiprotease imbalance, and oxidative stress overwhelming antioxidant defenses. In this review, we will discuss the major environmental and host sources for oxidative stress; discuss how oxidative stress regulates chronic bronchitis; review the latest information on genetic predisposition to COPD, specifically focusing on oxidant/antioxidant imbalance; and review future antioxidant therapeutic options for COPD. The complexity of COPD will necessitate a multi-target therapeutic approach. It is likely that antioxidant supplementation and dietary antioxidants will have a place in these future combination therapies. Keywords: cigarette smoking, mucins, gene regulation, Chinese herbs, acupuncture, dietary antioxidants

  13. Stormwater disinfection using Electrochemical oxidation

    OpenAIRE

    WENJUN FENG

    2017-01-01

    This thesis demonstrates that electrochemical oxidation can be a promising stormwater disinfection technique to achieve regulatory water re-uses targets. It discusses the implications for the practical implementation of the technology and identifies areas for future research in regards to optimisation of the technology

  14. Perovskite catalysts for oxidative coupling

    Science.gov (United States)

    Campbell, Kenneth D.

    1991-01-01

    Perovskites of the structure A.sub.2 B.sub.2 C.sub.3 O.sub.10 are useful as catalysts for the oxidative coupling of lower alkane to heavier hydrocarbons. A is alkali metal; B is lanthanide or lanthanum, cerium, neodymium, samarium, praseodymium, gadolinium or dysprosium; and C is titanium.

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

    Science.gov (United States)

    Najafpour, Mohammad Mahdi; Rahimi, Fahime; Fathollahzadeh, Maryam; Haghighi, Behzad; Hołyńska, Małgorzata; Tomo, Tatsuya; Allakhverdiev, Suleyman I

    2014-07-28

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

  16. The effects of fatty acid composition on lipid oxidation, protein oxidation and color stability in minced pork

    OpenAIRE

    Liu, Miao

    2017-01-01

    The literature review covers different aspects of lipid oxidation and protein oxidation in meat.The mechanism of lipid and protein oxidation, factors influencing lipid oxidation, the consequences of protein oxidation, measurement methods, and the interactions between lipid oxidation, protein oxidation and meat color are introduced. The present thesis was aiming to study the effects of different fatty acid composition on lipid oxidation, protein oxidation and meat color in minced pork st...

  17. The properties of protective oxide scales containing cerium on alloy 800H in oxidizing and oxidizing/sulphidizing environments

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Haanappel, V.A.C.; Fransen, T.; Geerdink, Bert; Gellings, P.J.; Stroosnijder, M.F.

    1991-01-01

    The corrosion protection of oxide scales formed by electrophoretic deposition in a cerium-containing sol on Alloy 800H, a 32Ni-20Cr steel, followed by firing in air at 1123 K was studied in oxidizing and mixed oxidizing/sulphidizing environments at elevated temperatures. In particular, the influence

  18. Oxidative stress in cardiovascular diseases

    Directory of Open Access Journals (Sweden)

    Shyamal K Goswami

    2015-01-01

    Full Text Available Oxidative stress caused by various oxygen containing free radicals and reactive species (collectively called "Reactive Oxygen Species" or ROS has long been attributed to cardiovascular diseases. In human body, major oxidizing species are super oxide, hydrogen peroxide, hydroxyl radical, peroxy nitrite etc. ROS are produced from distinct cellular sources, enzymatic and non-enzymatic; have specific physicochemical properties and often have specific cellular targets. Although early studies in nineteen sixties and seventies highlighted the deleterious effects of these species, later it was established that they also act as physiological modulators of cellular functions and diseases occur only when ROS production is deregulated. One of the major sources of cellular ROS is Nicotinamide adenine dinucleotide phosphate oxidases (Noxes that are expressed in almost all cell types. Superoxide and hydrogen peroxide generated from them under various conditions act as signal transducers. Due to their immense importance in cellular physiology, various Nox inhibitors are now being developed as therapeutics. Another free radical of importance in cardiovascular system is nitric oxide (a reactive nitrogen species generated from nitric oxide synthase(s. It plays a critical role in cardiac function and its dysregulated generation along with superoxide leads to the formation of peroxynitrite a highly deleterious agent. Despite overwhelming evidences of association between increased level of ROS and cardiovascular diseases, antioxidant therapies using vitamins and omega 3 fatty acids have largely been unsuccessful till date. Also, there are major discrepancies between studies with laboratory animals and human trials. It thus appears that the biology of ROS is far complex than anticipated before. A comprehensive understanding of the redox biology of diseases is thus needed for developing targeted therapeutics.

  19. Oxidation events and skin aging.

    Science.gov (United States)

    Kammeyer, A; Luiten, R M

    2015-05-01

    The rate of skin aging, or that of tissue in general, is determined by a variable predominance of tissue degeneration over tissue regeneration. This review discusses the role of oxidative events of tissue degeneration and aging in general, and for the skin in particular. The mechanisms involved in intrinsic and extrinsic (photo-) aging are described. Since photoaging is recognized as an important extrinsic aging factor, we put special emphasize on the effects of UV exposure on aging, and its variable influence according to global location and skin type. We here summarise direct photochemical effects of UV on DNA, RNA, proteins and vitamin D, the factors contributing to UV-induced immunosuppression, which may delay aging, the nature and origin of reactive oxygen species (ROS) and reactive nitrogen species (RNS) as indirect contributors for aging, and the consequences of oxidative events for extracellular matrix (ECM) degradation, such as that of collagen. We conclude that conflicting data on studies investigating the validity of the free radical damage theory of aging may reflect variations in the level of ROS induction which is difficult to quantify in vivo, and the lack of targeting of experimental ROS to the relevant cellular compartment. Also mitohormesis, an adaptive response, may arise in vivo to moderate ROS levels, further complicating interpretation of in vivo results. We here describes how skin aging is mediated both directly and indirectly by oxidative degeneration.This review indicates that skin aging events are initiated and often propagated by oxidation events, despite recently recognized adaptive responses to oxidative stress. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Inflammation, Oxidative Stress, and Obesity

    Directory of Open Access Journals (Sweden)

    José A. Morales-González

    2011-05-01

    Full Text Available Obesity is a chronic disease of multifactorial origin and can be defined as an increase in the accumulation of body fat. Adipose tissue is not only a triglyceride storage organ, but studies have shown the role of white adipose tissue as a producer of certain bioactive substances called adipokines. Among adipokines, we find some inflammatory functions, such as Interleukin-6 (IL-6; other adipokines entail the functions of regulating food intake, therefore exerting a direct effect on weight control. This is the case of leptin, which acts on the limbic system by stimulating dopamine uptake, creating a feeling of fullness. However, these adipokines induce the production of reactive oxygen species (ROS, generating a process known as oxidative stress (OS. Because adipose tissue is the organ that secretes adipokines and these in turn generate ROS, adipose tissue is considered an independent factor for the generation of systemic OS. There are several mechanisms by which obesity produces OS. The first of these is the mitochondrial and peroxisomal oxidation of fatty acids, which can produce ROS in oxidation reactions, while another mechanism is over-consumption of oxygen, which generates free radicals in the mitochondrial respiratory chain that is found coupled with oxidative phosphorylation in mitochondria. Lipid-rich diets are also capable of generating ROS because they can alter oxygen metabolism. Upon the increase of adipose tissue, the activity of antioxidant enzymes such as superoxide dismutase (SOD, catalase (CAT, and glutathione peroxidase (GPx, was found to be significantly diminished. Finally, high ROS production and the decrease in antioxidant capacity leads to various abnormalities, among which we find endothelial dysfunction, which is characterized by a reduction in the bioavailability of vasodilators, particularly nitric oxide (NO, and an increase in endothelium-derived contractile factors, favoring atherosclerotic disease.

  1. A novel marine nitrite-oxidizing

    NARCIS (Netherlands)

    Haaijer, S.C.M.; Ji, K.; van Niftrik, L.; Hoischen, A.; Speth, D.R.; Jetten, M.S.M.; Sinninghe Damsté, J.S.; Op den Camp, H.J.M.

    2013-01-01

    Marine microorganisms are important for the global nitrogen cycle, but marine nitrifiers, especially aerobic nitrite oxidizers, remain largely unexplored. To increase the number of cultured representatives of marine nitrite-oxidizing bacteria (NOB), a bioreactor cultivation approach was adopted to

  2. Graphene oxide-based transparent conductive films

    National Research Council Canada - National Science Library

    Zheng, Qingbin; Li, Zhigang; Yang, Junhe; Kim, Jang-Kyo

    2014-01-01

    .... Because of its excellent electrical conductivity, optical transparency and mechanical properties, graphene has been considered an ideal material to replace the existing, expensive indium tin oxide (ITO) as TCFs. Graphene oxide (GO...

  3. Consecutive dynamic resolutions of phosphine oxides

    NARCIS (Netherlands)

    Kortmann, Felix A.; Chang, Mu-Chieh; Otten, Edwin; Couzijn, Erik P. A.; Lutz, Martin; Minnaard, Adriaan J.

    2014-01-01

    A crystallization-induced asymmetric transformation (CIAT) involving a radical-mediated racemization provides access to enantiopure secondary phosphine oxides. A consecutive CIAT is used to prepare enantio-and diastereo-pure tert-butyl(hydroxyalkyl)phenylphosphine oxides.

  4. Complex oxides useful for thermoelectric energy conversion

    Science.gov (United States)

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

    2012-07-17

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

  5. Sodium Perborate Oxidation of an Aromatic Amine

    Science.gov (United States)

    Juestis, Laurence

    1977-01-01

    Describes an experiment involving the oxidation of aromatic primary amines to the corresponding azo compound; suggests procedures for studying factors that influence the yield of such a reaction, including the choice of solvent and the oxidant-amine ratio. (MLH)

  6. Nanostructured Metal Oxides Based Enzymatic Electrochemical Biosensors

    OpenAIRE

    Ansari, Anees A.; Alhoshan, M.; Alsalhi, M.S.; Aldwayyan, A.S.

    2010-01-01

    The unique electrocatalytic properties of the metal oxides and the ease of metal oxide nanostructured fabrication make them extremely interesting materials for electrochemical enzymatic biosensor applications. The application of nanostructured metal oxides in such sensing devices has taken off rapidly and will surely continue to expand. This article provides a review on current research status of electrochemical enzymatic biosensors based on various new types of nanostructured metal oxides su...

  7. The initial oxidation of magnesium

    Energy Technology Data Exchange (ETDEWEB)

    Kurth, M.

    2004-07-01

    Pure Magnesium samples have been oxidised in an UHV chamber under controlled conditions. Pressure range was 10{sup -10} Torr to 10{sup -7} Torr, temperature range was 273 K to 435 K. The samples have then been investigated with XPS, Ellipsometry and HERDA. Additionally, furnace oxidations at 750 Torr and 673 K have been carried out and investigated with XPS. From the XPS measurements data concerning layer thickness, composition, oxidation state and binding state have been gained. The ellipsometrie measurements yielded additional data concerning layer thickness as well as the size of the band gap of the developing oxide. With the HERDA measurements, the oxygen content within the oxide layer has been determined yielding additional information about composition and layer thickness. The layer thickness as a function of time have then been modelled with a kinetic growth model of Fromhold and Cook. For the refinement of the XPS data concerning layer thickness and composition, the pronounced plasmon excitations that occur in magnesium have been determined with two different procedures which have been developed in the methodical part of this work. The layer thickness and composition values have thus been corrected. Results: Two oxidation stages could be identified: a strong increase for the first few Langmuirs (1L = 1s x 10{sup -6} Torr), followed by a saturation'' region which was about 1.2 nm to 1.5 nm in magnitude. XPS and ellipsometry results have thereby been in very good agreement. The composition of the developing oxide showed a clear deviation from stoichiometric MgO, mainly caused by an oxygen deficiency; this deficiency has also been confirmed with the HERDA measurements. The Mg/O ratio as a function of layer thickness showed a continous decay starting from very high values for the thinnest layers (>{proportional_to}2.5) down to a saturation value of about 1.4, even for larger layer thicknesses gained with the furnace oxidations. The determination of

  8. Photocatalytic water oxidation with iron oxide hydroxide (rust) nanoparticles

    Science.gov (United States)

    Shelton, Timothy L.; Bensema, Bronwyn L.; Brune, Nicholas K.; Wong, Christopher; Yeh, Max; Osterloh, Frank E.

    2017-01-01

    Hematite has attracted considerable interest as a photoanode material for water oxidation under visible illumination. Here, we explore the limits of photocatalytic water oxidation activity with iron (III) oxide hydroxide nanocrystals and NaIO4 as a sacrificial electron acceptor (E=1.63 V NHE at pH=0.5). The sol was prepared by hydrolysis of FeCl3 in boiling 0.002-M HCl solution and confirmed to mainly consist of ß-FeO(OH) (akaganéite) particles with 5 to 15 nm diameter. From a 0.01 M aqueous NaIO4 solution, the sol evolves between 4.5 and 35.2 μmol O2 h-1, depending on pH, light intensity (>400 nm, 290 to 700 mW cm-2), ß-FeO(OH), and NaIO4 concentration. The activity increases with pH, and depends linearly on light intensity and photocatalyst amount, and it varies with sacrificial electron donor concentration. Under optimized conditions, the apparent quantum efficiency is 0.19% (at 400 nm and 460 mW cm-2), and the turnover number is 2.58 based on total ß-FeO(OH). Overall, the efficiency of the ß-FeO(OH)/NaIO4 photocatalytic system is limited by electron hole recombination and by particle aggregation over longer irradiation times (24 h). Lastly, surface photovoltage measurements on ß-FeO(OH) films on fluorine doped tin oxide substrate confirm a 2.15 eV effective band gap for the material.

  9. Oxygen Activation and Photoelectrochemical Oxidation on Oxide Surfaces

    Science.gov (United States)

    2013-12-04

    partial reduction to RuIII–O+ followed by rapid protonation, further reduction to RuII-OH2 2+, and cross-surface comproportionation, resulting in narrow...toluene, ethylbenzene, and cumene. Oxidation of hydrocarbons has a direct relation to fuel cell development and conversion of natural gas to liquid fuels...Since the hydrocarbons were not miscible with aqueous solutions, a new solvent system composed of propylene carbonate (PC) and 1 % water by volume

  10. Oxidation of phenolic acids by soil iron and manganese oxides

    Energy Technology Data Exchange (ETDEWEB)

    Lehmann, R.G.; Cheng, H.H.; Harsh, J.B.

    Phenolic acids are intermediary metabolites of many aromatic chemicals and may be involved in humus formation, allelopathy, and nutrient availability. Depending on their structures, six phenolic acids were shown to react at different rates with oxidized forms of Fe and Mn in a Palouse soil (fine-silty, mixed, mesic Pachic Ultic Haploxeroll). Increasing methoxy substitution on the aromatic ring of phenolic acids increased the reaction rate. Reaction rate was also increased for longer carboxyl-containing side chains. After 4 h reaction, little of the applied (10 mg kg/sup -1/ soil) p-hydroxybenzoic or p-coumaric acids had reacted, while 0 to 5, 70, 90, and 100% of the vanillic, ferulic, syringic, and sinapic acids, respectively, had reacted. After 72 h under conditions limiting microbial growth, none of the p-hydroxybenzoic, 30% of the p-coumaric, and 50% of the vanillic acids had reacted. The reaction was shown to be predominantly chemical, and not biological, since phenolic acid extractabilities were similar for Palouse soil and for Palouse soil pretreated with LiOBr to remove organic matter. When the Palouse soil was pretreated with a sodium dithionite-citrate solution to remove Fe and Mn oxides, none of the phenolic acids reacted after 1 h. The reaction of sinapic acid with Palouse soil was shown to produce Fe(II) and soluble Mn as reaction products. The reaction of phenolic acids with soil was thus shown to be an oxidation of the phenolic acids, coupled with a reduction of soil Fe and Mn oxides.

  11. Structure and catalytic reactivity of Rh oxides

    DEFF Research Database (Denmark)

    Gustafson, J.; Westerström, R.; Resta, A.

    2009-01-01

    Using a combination of experimental and theoretical techniques, we show that a thin RhO2 surface oxide film forms prior to the bulk Rh2O3 corundum oxide on all close-packed single crystal Rh surfaces. Based on previous reports, we argue that the RhO2 surface oxide also forms on vicinal Rh surface...

  12. 21 CFR 582.5431 - Magnesium oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium oxide. 582.5431 Section 582.5431 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5431 Magnesium oxide. (a) Product. Magnesium oxide. (b) Conditions of use. This substance...

  13. 21 CFR 582.1431 - Magnesium oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium oxide. 582.1431 Section 582.1431 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1431 Magnesium oxide. (a) Product. Magnesium oxide. (b) Conditions of use. This substance is...

  14. 76 FR 38036 - Propylene Oxide; Pesticide Tolerances

    Science.gov (United States)

    2011-06-29

    ... AGENCY 40 CFR Part 180 Propylene Oxide; Pesticide Tolerances AGENCY: Environmental Protection Agency (EPA). ACTION: Final rule. SUMMARY: This regulation amends the propylene oxide tolerance on ``nut, tree, group...), announcing the Agency's proposal to amend the propylene oxide tolerance (40 CFR 180.491) on ``nut, tree...

  15. 77 FR 28493 - Propylene Oxide; Tolerance Actions

    Science.gov (United States)

    2012-05-15

    ... AGENCY 40 CFR Part 180 RIN 2070-ZA16 Propylene Oxide; Tolerance Actions AGENCY: Environmental Protection... separate tolerances on pistachio and pine nuts for both the fumigant propylene oxide and the reaction product from the use of propylene oxide, known as propylene chlorohydrin, to cover all registered uses on...

  16. Nitric oxide in the rat vestibular system.

    Science.gov (United States)

    Harper, A; Blythe, W R; Zdanski, C J; Prazma, J; Pillsbury, H C

    1994-10-01

    Nitric oxide is known to function as a neurotransmitter in the central nervous system. It is also known to be involved in the central nervous system excitatory amino acid neurotransmission cascade. Activation of excitatory amino acid receptors causes an influx of calcium, which activates nitric oxide synthase. The resulting increase in intracellular nitric oxide activates soluble guanylate cyclase, leading to a rise in cyclic guanosine monophosphate. The excitatory amino acids glutamate and aspartate are found in the vestibular system and have been postulated to function as vestibular system neurotransmitters. Although nitric oxide has been investigated as a neurotransmitter in other tissues, no published studies have examined the role of nitric oxide in the vestibular system. Neuronal NADPH-diaphorase has been characterized as a nitric oxide synthase. This enzyme catalyzes the conversion of L-arginine to L-citrulline, producing nitric oxide during the reaction. We used a histochemical stain characterized by Hope et al. (Proc Natl Acad Sci 1991;88:2811) as specific for neuronal nitric oxide synthase to localize the enzyme in the rat vestibular system. An immunocytochemical stain was used to examine rat inner ear tissue for the presence of the enzyme's end product, L-citrulline, thereby demonstrating nitric oxide synthase activity. Staining of vestibular ganglion sections showed nitric oxide synthase presence and activity in ganglion cells and nerve fibers. These results indicate the presence of active nitric oxide synthase in these tissues and suggest modulation of vestibular neurotransmission by nitric oxide.

  17. Protective role of endothelial nitric oxide synthase

    NARCIS (Netherlands)

    Albrecht, Ester W J A; Stegeman, Coen A; Heeringa, Peter; Henning, Robert; van Goor, Harry

    Nitric oxide is a versatile molecule, with its actions ranging from haemodynamic regulation to anti-proliferative effects on vascular smooth muscle cells. Nitric oxide is produced by the nitric oxide synthases, endothelial NOS (eNOS), neural NOS (nNOS), and inducible NOS (iNOS). Constitutively

  18. Characterization And Dissolution Properties Of Ruthenium Oxides

    Science.gov (United States)

    Ruthenium oxides (RuO2•1.10H2O and RuO2) have been synthesized by forced hydrolysis and oxidation of ruthenium chloride. The resulting materials were extensively characterized to determine the crystallinity, surface area, and ruthenium oxidation ...

  19. Processes regulating nitric oxide emissions from soils

    DEFF Research Database (Denmark)

    Pilegaard, Kim

    2013-01-01

    Nitric oxide (NO) is a reactive gas that plays an important role in atmospheric chemistry by influencing the production and destruction of ozone and thereby the oxidizing capacity of the atmosphere. NO also contributes by its oxidation products to the formation of acid rain. The major sources...

  20. Nitrous oxide emissions from estuarine intertidal sediments

    NARCIS (Netherlands)

    Middelburg, J.J.; Klaver, G.; Nieuwenhuize, J.; Markusse, R.M.; Vlug, T.; Nat, F.J.W.A. van der

    1995-01-01

    From September 1990 through December 1991 nitrous oxide flux measurements were made at 9 intertidal mud flat sites in the Scheldt Estuary. Nitrous oxide release rates were highly variable both between sites and over time at any one site. Annual nitrous oxide fluxes vary from about 10 mmol N m-2 at

  1. 29 CFR 1910.105 - Nitrous oxide.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 5 2010-07-01 2010-07-01 false Nitrous oxide. 1910.105 Section 1910.105 Labor Regulations... OCCUPATIONAL SAFETY AND HEALTH STANDARDS Hazardous Materials § 1910.105 Nitrous oxide. The piped systems for the in-plant transfer and distribution of nitrous oxide shall be designed, installed, maintained, and...

  2. Separation medium containing thermally exfoliated graphite oxide

    Science.gov (United States)

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

    2012-01-01

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

  3. 21 CFR 582.5991 - Zinc oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Zinc oxide. 582.5991 Section 582.5991 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS... 1 § 582.5991 Zinc oxide. (a) Product. Zinc oxide. (b) Conditions of use. This substance is generally...

  4. 21 CFR 73.2991 - Zinc oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Zinc oxide. 73.2991 Section 73.2991 Food and Drugs... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2991 Zinc oxide. (a) Identity and specifications. The color additive zinc oxide shall conform in identity and specifications to the requirements of § 73.1991...

  5. 21 CFR 73.1991 - Zinc oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Zinc oxide. 73.1991 Section 73.1991 Food and Drugs... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1991 Zinc oxide. (a) Identity. (1) The color additive zinc...). It is principally composed of Zn. (2) Color additive mixtures for drug use made with zinc oxide may...

  6. 21 CFR 182.8991 - Zinc oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Zinc oxide. 182.8991 Section 182.8991 Food and... CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8991 Zinc oxide. (a) Product. Zinc oxide. (b) Conditions of use. This substance is generally recognized as safe when used in...

  7. Thermal Oxidation of Structured Silicon Dioxide

    DEFF Research Database (Denmark)

    Christiansen, Thomas Lehrmann; Hansen, Ole; Jensen, Jørgen Arendt

    2014-01-01

    The topography of thermally oxidized, structured silicon dioxide is investigated through simulations, atomic force microscopy, and a proposed analytical model. A 357 nm thick oxide is structured by removing regions of the oxide in a masked etch with either reactive ion etching or hydrofluoric acid...

  8. p53, oxidative stress, and aging.

    Science.gov (United States)

    Liu, Dongping; Xu, Yang

    2011-09-15

    Mammalian aging is associated with elevated levels of oxidative damage of DNA, proteins, and lipids as a result of unbalanced prooxidant and antioxidant activities. Accumulating evidence indicates that oxidative stress is a major physiological inducer of aging. p53, the guardian of the genome that is important for cellular responses to oxidative stresses, might be a key coordinator of oxidative stress and aging. In response to low levels of oxidative stresses, p53 exhibits antioxidant activities to eliminate oxidative stress and ensure cell survival; in response to high levels of oxidative stresses, p53 exhibits pro-oxidative activities that further increase the levels of stresses, leading to cell death. p53 accomplishes these context-dependent roles by regulating the expression of a panel of genes involved in cellular responses to oxidative stresses and by modulating other pathways important for oxidative stress responses. The mechanism that switches p53 function from antioxidant to prooxidant remains unclear, but could account for the findings that increased p53 activities have been linked to both accelerated aging and increased life span in mice. Therefore, a balance of p53 antioxidant and prooxidant activities in response to oxidative stresses could be important for longevity by suppressing the accumulation of oxidative stresses and DNA damage.

  9. Myoglobin-induced lipid oxidation : A review

    DEFF Research Database (Denmark)

    Baron, Caroline; Andersen, H.J.

    2002-01-01

    An overview of myoglobin-initiated lipid oxidation in simple model systems, muscle, and muscle-based foods is presented. The potential role of myoglobin spin and redox states in initiating lipid oxidation is reviewed. Proposed mechanisms for myoglobin- initiated lipid oxidation in muscle tissue (p...

  10. 21 CFR 184.1431 - Magnesium oxide.

    Science.gov (United States)

    2010-04-01

    ... powder (light) or a relatively dense white powder (heavy) by heating magnesium hydroxide or carbonate... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium oxide. 184.1431 Section 184.1431 Food and... Substances Affirmed as GRAS § 184.1431 Magnesium oxide. (a) Magnesium oxide (MgO, CAS Reg. No. 1309-48-4...

  11. Graphene oxide reduction recipes, spectroscopy, and applications

    CERN Document Server

    Gao, Wei

    2015-01-01

    This book focuses on a group of new materials labeled ""graphene oxides."" It provides a comprehensive overview of graphene oxide-based nanomaterials in terms of their synthesis, structures, properties, and extensive applications in catalysis, separation, filtration, energy storage and conversion. The book also covers emerging research on graphite oxides and the impact of the research on fundamental and applied sciences.

  12. Air Quality Criteria for Sulfur Oxides.

    Science.gov (United States)

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

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

  13. 21 CFR 73.3125 - Iron oxides.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Iron oxides. 73.3125 Section 73.3125 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3125 Iron oxides. (a) Identity and specifications. The color additive iron oxides (CAS Reg. No. 1332-37-2), Color Index No. 77491, shall conform in...

  14. Polyaniline: Aniline oxidation with strong and weak oxidants under various acidity

    Energy Technology Data Exchange (ETDEWEB)

    Bláha, Michal, E-mail: blaha@imc.cas.cz [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, 162 06 Prague 6 (Czech Republic); Trchová, Miroslava; Bober, Patrycja; Morávková, Zuzana [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, 162 06 Prague 6 (Czech Republic); Prokeš, Jan [Charles University, Faculty of Mathematics and Physics, 180 00 Prague 8 (Czech Republic); Stejskal, Jaroslav [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, 162 06 Prague 6 (Czech Republic)

    2017-06-15

    Aniline was oxidized with three strong inorganic oxidants (ammonium peroxydisulfate, cerium(IV) sulfate, potassium dichromate), two weak inorganic oxidants (iron(III) chloride, silver nitrate), and one organic oxidant (p-benzoquinone) in aqueous solutions of methanesulfonic acid (MSA) of various concentration. Whereas oxidation of aniline with ammonium peroxydisulfate yielded high-molecular-weight conducting polyaniline (PANI) in the whole acidity range, the oxidation with cerium(IV) sulfate led also to a single product close to PANI with considerably lower molecular weight and lower conductivity. Potassium dichromate gave PANI only at high concentration of MSA. The use of iron(III) chloride yielded composite mixtures of PANI and low-molecular-weight aniline oligomers. The oxidation of aniline with silver nitrate led to composites of silver and an organic part, which was constituted either by aniline oligomers or conducting polyaniline or both. p-Benzoquinone as oxidant produced mainly aniline oligomers with poor conductivity and 2,5-dianilino-p-benzoquinone-like structure detected in FTIR and Raman spectra when oxidation proceeded with weak oxidants. A general model of oxidation with strong and weak oxidants was formulated. - Highlights: • Comparison of aniline oxidation with oxidants of different redox potential. • UV–vis, FTIR and Raman spectroscopies combined with size-exclusion chromatography. • The contents of polymer and oligomers were analyzed and discussed. • General model of aniline oxidation with strong and weak oxidants was formulated.

  15. Fatty acid omega-oxidation as a rescue pathway for fatty acid oxidation disorders in humans

    NARCIS (Netherlands)

    Wanders, Ronald J. A.; Komen, Jasper; Kemp, Stephan

    2011-01-01

    Fatty acids (FAs) can be degraded via different mechanisms including alpha-, beta- and omega-oxidation. In humans, a range of different genetic diseases has been identified in which either mitochondrial FA beta-oxidation, peroxisomal FA beta-oxidation or FA alpha-oxidation is impaired. Treatment

  16. Advanced methods for the treatment of organic aqueous wastes: wet air oxidation and wet peroxide oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Debellefontaine, Hubert; Chakchouk, Mehrez; Foussard, Jean Noel [Institut National des Sciences Appliquees (INSA), 31 - Toulouse (France). Dept. de Genie des Procedes Industriels; Tissot, Daniel; Striolo, Phillipe [IDE Environnement S.A., Toulouse (France)

    1993-12-31

    There is a growing concern about the problems of wastes elimination. Various oxidation techniques are suited for elimination of organic aqueous wastes, however, because of the environmental drawbacks of incineration, liquid phase oxidation should be preferred. `Wet Air Oxidation` and `Wet Peroxide Oxidation`are alternative processes which are discussed in this paper. 17 refs., 13 figs., 4 tabs.

  17. Oxidation of positronium atoms on a surface of oxidic catalyst carrier containing acid centres

    CERN Document Server

    Paiziev, A A

    2000-01-01

    By Born approximation the cross section of positronium (Ps) oxidation on acid centres localized on the surface of oxide carriers is calculated. Analysis of the kinetics of elementary processes in porous carriers based on aluminum oxide including processes of annihilation of positron, formation of Ps and oxidation of Ps on acid centres is given.

  18. Oxidized limonene and oxidized linalool - concomitant contact allergy to common fragrance terpenes

    DEFF Research Database (Denmark)

    Bråred Christensson, Johanna; Karlberg, Ann-Therese; Andersen, Klaus E

    2016-01-01

    BACKGROUND: Limonene and linalool are common fragrance terpenes. Both oxidized R-limonene and oxidized linalool have recently been patch tested in an international setting, showing contact allergy in 5.2% and 6.9% of dermatitis patients, respectively. OBJECTIVE: To investigate concomitant reactions...... between oxidized R-limonene and oxidized linalool in consecutive dermatitis patients. METHODS: Oxidized R-limonene 3.0% (containing limonene hydroperoxides 0.33%) and oxidized linalool 6% (linalool hydroperoxides 1%) in petrolatum were tested in 2900 consecutive dermatitis patients in Australia, Denmark......, Singapore, Spain, Sweden, and the United Kingdom. RESULTS: A total of 281 patients reacted to either oxidized R-limonene or oxidized linalool. Of these, 25% had concomitant reactions to both compounds, whereas 29% reacted only to oxidized R-limonene and 46% only to oxidized linalool. Of the 152 patients...

  19. Synthesis of Graphene Oxide by Oxidation of Graphite with Ferrate(VI) Compounds: Myth or Reality?

    Science.gov (United States)

    Sofer, Zdeněk; Luxa, Jan; Jankovský, Ondřej; Sedmidubský, David; Bystroň, Tomáš; Pumera, Martin

    2016-09-19

    It is well established that graphene oxide can be prepared by the oxidation of graphite using permanganate or chlorate in an acidic environment. Recently, however, the synthesis of graphene oxide using potassium ferrate(VI) ions has been reported. Herein, we critically replicate and evaluate this new ferrate(VI) oxidation method. In addition, we test the use of potassium ferrate(VI) for the synthesis of graphene oxide under various experimental routes. The synthesized materials are analyzed by a number of analytical methods in order to confirm or disprove the possibility of synthesizing graphene oxide by the ferrate(VI) oxidation route. Our results confirm the unsuitability of using ferrate(VI) for the oxidation of graphite on graphene oxide because of its high instability in an acidic environment and low oxidation power in neutral and alkaline environments. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Production of oceanic nitrous oxide by ammonia-oxidizing archaea

    Directory of Open Access Journals (Sweden)

    C. R. Löscher

    2012-07-01

    Full Text Available The recent finding that microbial ammonia oxidation in the ocean is performed by archaea to a greater extent than by bacteria has drastically changed the view on oceanic nitrification. The numerical dominance of archaeal ammonia-oxidizers (AOA over their bacterial counterparts (AOB in large parts of the ocean leads to the hypothesis that AOA rather than AOB could be the key organisms for the oceanic production of the strong greenhouse gas nitrous oxide (N2O that occurs as a by-product of nitrification. Very recently, enrichment cultures of marine ammonia-oxidizing archaea have been reported to produce N2O.

    Here, we demonstrate that archaeal ammonia monooxygenase genes (amoA were detectable throughout the water column of the eastern tropical North Atlantic (ETNA and eastern tropical South Pacific (ETSP Oceans. Particularly in the ETNA, comparable patterns of abundance and expression of archaeal amoA genes and N2O co-occurred in the oxygen minimum, whereas the abundances of bacterial amoA genes were negligible. Moreover, selective inhibition of archaea in seawater incubations from the ETNA decreased the N2O production significantly. In studies with the only cultivated marine archaeal ammonia-oxidizer Nitrosopumilus maritimus SCM1, we provide the first direct evidence for N2O production in a pure culture of AOA, excluding the involvement of other microorganisms as possibly present in enrichments. N. maritimus showed high N2O production rates under low oxygen concentrations comparable to concentrations existing in the oxycline of the ETNA, whereas the N2O production from two AOB cultures was comparably low under similar conditions. Based on our findings, we hypothesize that the production of N2O in tropical ocean areas results mainly from archaeal nitrification and will be affected by the predicted decrease in dissolved

  1. Antimony oxidation and adsorption by in-situ formed biogenic Mn oxide and Fe-Mn oxides.

    Science.gov (United States)

    Bai, Yaohui; Jefferson, William A; Liang, Jinsong; Yang, Tingting; Qu, Jiuhui

    2017-04-01

    Antimony (Sb), which can be toxic at relatively low concentrations, may co-exist with Mn(II) and/or Fe(II) in some groundwater and surface water bodies. Here we investigated the potential oxidation and adsorption pathways of Sb (III and V) species in the presence of Mn(II) and Mn-oxidizing bacteria, with or without Fe(II). Batch experiments were conducted to determine the oxidation and adsorption characteristics of Sb species in the presence of biogenic Mn oxides (BMOs), which were formed in-situ via the oxidation of Mn(II) by a Mn-oxidizing bacterium (Pseudomonas sp. QJX-1). Results indicated that Sb(III) ions could be oxidized to Sb(V) ions by BMO, but only Sb(V) originating from Sb(III) oxidation was adsorbed effectively by BMO. Introduced Fe(II) was chemically oxidized to FeOOH, the precipitates of which mixed with BMO to form a new compound, biogenic Fe-Mn oxides (BFMO). The BMO part of the BFMO mainly oxidized and the FeOOH of the BFMO mainly adsorbed the Sb species. In aquatic solutions containing both As(III) and Sb(III), the BFMO that formed in-situ preferentially oxidized Sb over As but adsorbed As more efficiently. Chemical analysis and reverse transcription real-time polymerase chain reaction revealed that the presence of Fe(II), As(III) and Sb(III) accelerated the oxidation of Mn(II) but inhibited the activity of Mn-oxidizing bacteria. These results provide significant insights into the biogeochemical pathways of Sb, Mn(II) in aquatic ecosystems, with or without Fe(II). Copyright © 2016. Published by Elsevier B.V.

  2. Haemophilus influenzae and oxidative stress

    Directory of Open Access Journals (Sweden)

    Alistair eHarrison

    2012-03-01

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

  3. Biochemistry of Dissimilatory Sulfur Oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Blake II, R.

    2003-05-30

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

  4. Graphene Oxides Show Angiogenic Properties.

    Science.gov (United States)

    Mukherjee, Sudip; Sriram, Pavithra; Barui, Ayan Kumar; Nethi, Susheel Kumar; Veeriah, Vimal; Chatterjee, Suvro; Suresh, Kattimuttathu Ittara; Patra, Chitta Ranjan

    2015-08-05

    Angiogenesis, a process resulting in the formation of new capillaries from the pre-existing vasculature plays vital role for the development of therapeutic approaches for cancer, atherosclerosis, wound healing, and cardiovascular diseases. In this report, the synthesis, characterization, and angiogenic properties of graphene oxide (GO) and reduced graphene oxide (rGO) have been demonstrated, observed through several in vitro and in vivo angiogenesis assays. The results here demonstrate that the intracellular formation of reactive oxygen species and reactive nitrogen species as well as activation of phospho-eNOS and phospho-Akt might be the plausible mechanisms for GO and rGO induced angiogenesis. The results altogether suggest the possibilities for the development of alternative angiogenic therapeutic approach for the treatment of cardiovascular related diseases where angiogenesis plays a significant role. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. [Oxidative stress in Crohn's disease].

    Science.gov (United States)

    Moret, Inés; Cerrillo, Elena; Navarro-Puche, Ana; Iborra, Marisa; Rausell, Francisco; Tortosa, Luis; Beltrán, Belén

    2014-01-01

    Crohn's disease (CD) is characterized by transmural inflammation that is most frequently located in the region of the terminal ileum. Although the physiopathological mechanisms of the disease are not yet well defined, the unregulated immune response is associated with high production of reactive oxygen species (ROS). These elements are associated with complex systems known as antioxidant defenses, whose function is ROS regulation, thereby preventing the harmful effects of these elements. However, the presence of an imbalance between ROS production and ROS elimination by antioxidants has been widely described and leads to oxidative stress. In this article, we describe the most significant findings on oxidative stress in the intestinal mucosa and peripheral blood. Copyright © 2013 Elsevier España, S.L. and AEEH y AEG. All rights reserved.

  6. Oxidative Stress in Emergency Toxicology

    Directory of Open Access Journals (Sweden)

    M. V. Belova

    2009-01-01

    Full Text Available Objective: to comparatively assess the intensity of oxidative stress (OS in acute poisonings by various toxic chemicals. Subjects and methods. Two hundred and eighty-seven patients with acute poisoning by psychopharmacological agents, ethanol, and cauterants were examined. Results. A correlation was found between the manifestations of OS and the severity of poisoning. The investigators revealed the impacts of exposure to toxic chemicals and complications of the toxicogenic phase of acute poisoning by the above toxicants on the intensity of OS. Conclusion. The intensity of OS in the poisonings under study increases in proportion to the severity of intoxication, toxicant exposure in the body. The presence of hemolysis, upper airway burn, and chronic alcoholism deteriorate OS. Key words: oxidative stress, acute poisonings, chemical burn, chronic alcoholism.

  7. Oxidative stress in brain ischemia.

    Science.gov (United States)

    Love, S

    1999-01-01

    Brain ischemia initiates a complex cascade of metabolic events, several of which involve the generation of nitrogen and oxygen free radicals. These free radicals and related reactive chemical species mediate much of damage that occurs after transient brain ischemia, and in the penumbral region of infarcts caused by permanent ischemia. Nitric oxide, a water- and lipid-soluble free radical, is generated by the action of nitric oxide synthases. Ischemia causes a surge in nitric oxide synthase 1 (NOS 1) activity in neurons and, possibly, glia, increased NOS 3 activity in vascular endothelium, and later an increase in NOS 2 activity in a range of cells including infiltrating neutrophils and macrophages, activated microglia and astrocytes. The effects of ischemia on the activity of NOS 1, a Ca2+-dependent enzyme, are thought to be secondary to reversal of glutamate reuptake at synapses, activation of NMDA receptors, and resulting elevation of intracellular Ca2+. The up-regulation of NOS 2 activity is mediated by transcriptional inducers. In the context of brain ischemia, the activity of NOS 1 and NOS 2 is broadly deleterious, and their inhibition or inactivation is neuroprotective. However, the production of nitric oxide in blood vessels by NOS 3, which, like NOS 1, is Ca2+-dependent, causes vasodilatation and improves blood flow in the penumbral region of brain infarcts. In addition to causing the synthesis of nitric oxide, brain ischemia leads to the generation of superoxide, through the action of nitric oxide synthases, xanthine oxidase, leakage from the mitochondrial electron transport chain, and other mechanisms. Nitric oxide and superoxide are themselves highly reactive but can also combine to form a highly toxic anion, peroxynitrite. The toxicity of the free radicals and peroxynitrite results from their modification of macromolecules, especially DNA, and from the resulting induction of apoptotic and necrotic pathways. The mode of cell death that prevails probably

  8. Exfoliation of graphite oxide in propylene carbonate and thermal reduction of the resulting graphene oxide platelets.

    Science.gov (United States)

    Zhu, Yanwu; Stoller, Meryl D; Cai, Weiwei; Velamakanni, Aruna; Piner, Richard D; Chen, David; Ruoff, Rodney S

    2010-02-23

    Graphite oxide was exfoliated and dispersed in propylene carbonate (PC) by bath sonication. Heating the graphene oxide suspensions at 150 degrees C significantly reduced the graphene oxide platelets; paper samples comprising such reduced graphene oxide platelets had an electrical conductivity of 5230 S/m. By adding tetraethylammonium tetrafluoroborate (TEA BF(4)) to the reduced graphene oxide/PC slurry and making a two-cell ultracapacitor, specific capacitance values of about 120 F/g were obtained.

  9. Synthesis and characterization of manganese oxide and cobalt oxide nano-structure

    OpenAIRE

    F. Piri; N. Shakour; M. Zandi; R KARIMIAN

    2011-01-01

    The preparation of nanostructure type manganese oxide and cobalt oxide materials with the smallest particle size is reported here. The nanorod manganese oxide and cobalt oxide nanotube were prepared via a sol-gel reaction in reverse micelles from KMnO4 and CoCl2 with respectively source at room-temperature. The structure and surface morphology of the obtained manganese oxide were studied by means of X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and transmission electron...

  10. Graphene oxide physics and applications

    CERN Document Server

    Zhao, Jijun; Li, Fen

    2015-01-01

    This book gives a comprehensive overview of graphene oxides (GO)  from atomic structures and fundamental properties to technological applications. Atomic structural models, electronic properties, mechanical properties, optical properties, and functionalizing and compositing of GO are illustrated. Moreover, the excellent physical and chemical properties offer GO promising applications in electronic nanodevices, chemical sensors and catalyst, energy storage, and biotechnology, which are also presented in this book. Therefore, this book is of interest to researchers in physics, chemistry, materials science, and nanoscience.

  11. Lattice dynamics of lithium oxide

    Indian Academy of Sciences (India)

    for Li2O oxide may be transferred to other similar fluorites and antifluorites like. Na2O, K2O, UO2, ThO2 etc., with suitable modifications. References. [1] T W D Farley, W Hayes, S Hull, M T Hutchings and M Vrtis, J. Phys. Condens. Matter 3, 4761 (1991). [2] R W G Wyckoff, Crystal structures, 2nd ed. (John Wiley & Sons, New ...

  12. Electron collisions with nitrous oxide

    OpenAIRE

    Winstead, Carl; McKoy, Vincent

    1998-01-01

    We have carried out theoretical studies of low-energy elastic electron collisions with nitrous oxide (N2O), obtaining differential, integral, and momentum-transfer cross sections. Polarization effects are incorporated in the electron-molecule scattering dynamics. A simple, objective, and physically motivated criterion is introduced for constructing a compact set of configurations that accurately accounts for polarization in resonant symmetries while avoiding overcorrelation. Our cross section...

  13. Coal combustion by wet oxidation

    Energy Technology Data Exchange (ETDEWEB)

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

    1980-11-15

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

  14. Physical activity and lipid oxidation

    OpenAIRE

    Marrugat, Jaume; Arquer, Andreu; Elosua, Roberto

    2010-01-01

    Regular physical activity (PA) is associated with lower cardiovascular mortality and morbidity. Part of these benefits is related to the effects over the classic cardiovascular risk factors. These effects, however, only explain part of the protection of PA from these types of diseases. The oxidation of LDL cholesterol particles, which is the aetiopathogenic mechanism of a great part of cardiovascular diseases, plays an important role in the arteriosclerotic process. This narrative review pres...

  15. Oxidation pond for municipal wastewater treatment

    Science.gov (United States)

    Butler, Erick; Hung, Yung-Tse; Suleiman Al Ahmad, Mohammed; Yeh, Ruth Yu-Li; Liu, Robert Lian-Huey; Fu, Yen-Pei

    2017-03-01

    This literature review examines process, design, and cost issues related to using oxidation ponds for wastewater treatment. Many of the topics have applications at either full scale or in isolation for laboratory analysis. Oxidation ponds have many advantages. The oxidation pond treatment process is natural, because it uses microorganisms such as bacteria and algae. This makes the method of treatment cost-effective in terms of its construction, maintenance, and energy requirements. Oxidation ponds are also productive, because it generates effluent that can be used for other applications. Finally, oxidation ponds can be considered a sustainable method for treatment of wastewater.

  16. Accelerated ageing of molybdenum oxide

    Science.gov (United States)

    Jorge, Marina; Cooil, Simon; Edmonds, Mark T.; Thomsen, Lars; Nematollahi, Mohammadreza; Mazzola, Federico; Wells, Justin W.

    2017-11-01

    The stability and lifetime of materials proposed for photovoltaic applications are important parameters, because such devices should offer long-term reliable performance whilst operating in a harsh environment. In this work, we present a powerful approach to accelerate and study the degradation mechanisms of molybdenum oxide, a material which has shown promise for next generation photovoltaics, and for enhanced hole extraction in organic photovoltaics. We use UV and soft x-rays to drive accelerated ageing, boosting the ageing time by a factor of up to 1000. Using this method, we find that molybdenum oxide does not offer reliable performance in environments in which heating or ionising radiation are present, because of its propensity to reduce, thus strongly modifying its electronic properties. We estimate that  ≈100 d of unfiltered sunlight exposure would be sufficient to reduce this material into metallic MoO2. We also show that a very similar degradation can be driven by thermally, and that in both cases, the creation of oxygen vacancies is responsible. A lack of robustness to harsh operating conditions (i.e. UV and/or heat) brings the suitability of unprotected molybdenum oxide in photovoltaic applications into question.

  17. Nylon/Graphene Oxide Electrospun Composite Coating

    Directory of Open Access Journals (Sweden)

    Carmina Menchaca-Campos

    2013-01-01

    Full Text Available Graphite oxide is obtained by treating graphite with strong oxidizers. The bulk material disperses in basic solutions yielding graphene oxide. Starting from exfoliated graphite, different treatments were tested to obtain the best graphite oxide conditions, including calcination for two hours at 700°C and ultrasonic agitation in acidic, basic, or peroxide solutions. Bulk particles floating in the solution were filtered, rinsed, and dried. The graphene oxide obtained was characterized under SEM and FTIR techniques. On the other hand, nylon 6-6 has excellent mechanical resistance due to the mutual attraction of its long chains. To take advantage of the properties of both materials, they were combined as a hybrid material. Electrochemical cells were prepared using porous silica as supporting electrode of the electrospun nylon/graphene oxide films for electrochemical testing. Polarization curves were performed to determine the oxidation/reduction potentials under different acidic, alkaline, and peroxide solutions. The oxidation condition was obtained in KOH and the reduction in H2SO4 solutions. Potentiostatic oxidation and reduction curves were applied to further oxidize carbon species and then reduced them, forming the nylon 6-6/functionalized graphene oxide composite coating. Electrochemical impedance measurements were performed to evaluate the coating electrochemical resistance and compared to the silica or nylon samples.

  18. Phase-field model of oxidation: Equilibrium.

    Science.gov (United States)

    Sherman, Q C; Voorhees, P W

    2017-03-01

    A phase-field model of an oxide relevant to corrosion resistant alloys for film thicknesses below the Debye length L_{D}, where charge neutrality in the oxide does not occur, is formulated. The phase-field model is validated in the Wagner limit using a sharp interface Gouy-Chapman model for the electrostatic double layer. The phase-field simulations show that equilibrium oxide films below the Wagner limit are charged throughout due to their inability to electrostatically screen charge over the length of the film, L. The character of the defect and charge distribution profiles in the oxide vary depending on whether reduced oxygen adatoms are present on the gas-oxide interface. The Fermi level in the oxide increases for thinner films, approaching the Fermi level of the metal in the limit L/L_{D}→0, which increases the driving force for adsorbed oxygen reduction at the gas-oxide interface.

  19. Oxidative stress in university students during examinations.

    Science.gov (United States)

    Sivonová, Monika; Zitnanová, Ingrid; Hlincíková, Lucia; Skodácek, Igor; Trebatická, Jana; Duracková, Zdenka

    2004-09-01

    Mental stress in psychiatric disease and in daily life contributes to oxidative stress in the body. In this study we investigated a connection between possible psychological stress caused by university undergraduate examinations and oxidative stress experienced by our test subjects. Some parameters of oxidative stress (single strand breaks of DNA in lymphocytes, sensitivity to lipid oxidation and antioxidant status) were studied in medical students on the day of the examination (stress condition) and compared with the same parameters obtained from the same students during the term between two examination periods (non-stress condition). The results show that in the stress condition oxidative damage to DNA and sensitivity to lipid oxidation were significantly increased (pstress" conditions. A significant decrease in plasma antioxidant activity (pstress was observed. These results suggest that during university examinations students are under increased oxidative stress.

  20. Oxidation-reduction catalyst and its process of use

    Science.gov (United States)

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

    2008-01-01

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

  1. Plasma electrolytic oxide coatings on silumin for oxidation CO

    Science.gov (United States)

    Borisov, V. A.; Sigaeva, S. S.; Anoshkina, E. A.; Ivanov, A. L.; Litvinov, P. V.; Vedruchenko, V. R.; Temerev, V. L.; Arbuzov, A. B.; Kuznetsov, A. A.; Mukhin, V. A.; Suprunov, G. I.; Chumychko, I. A.; Shlyapin, D. A.; Tsyrul'nikov, P. G.

    2017-08-01

    Some catalysts of CO oxidation on silumin alloy AK12M2, used for the manufacture of pistons for Russian cars were investigated. The catalysts were prepared by the method of plasma electrolytic oxidation of silumin in electrolytes of various compositions with further activation by the salts Ce, Cu, Co, Ni, Mn and Al. The catalytic tests were carried out in a flow reactor in a mixture of 1% CO and 99% air, with the temperature range of 25-500 °C. The most active catalysts in CO oxidation are those activated with Ce and Cu salts on silumin, treated for 3 hours in an electrolyte containing 4 g/l KOH, 40 g/l Na2B4O7 (conversion of CO is 93.7% at a contact time of 0.25 s). However, the catalysts obtained from silumin treated in the electrolyte containing 3 g/l KOH, 30 g/l Na2SiO3 are more suitable for practical usage. Because when the treatment time of those catalysts is 10 - 20 minutes it is possible to achieve comparable CO conversion. The morphology and composition of the catalysts were studied by the methods of a scanning electron microscope with energy-dispersive surface analysis and X-ray phase analysis. The surface of the non-activated sample consists of γ-Al2O3 and SiO2 particles, due to which the active components get attached to the support. CeO2 and CuO are present on the surface of the sample with the active component.

  2. 75 FR 61486 - Review of the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Oxides...

    Science.gov (United States)

    2010-10-05

    ... AGENCY Review of the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Oxides... Standards for Oxides of Nitrogen and Oxides of Sulfur: Second External Review Draft (75 FR 57463, September... (summary of options for elements of the nitrogen oxides (NO X ) and sulfur oxides (SO X ) standard). DATES...

  3. 75 FR 20595 - Review of the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Oxides...

    Science.gov (United States)

    2010-04-20

    ... AGENCY Review of the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Oxides... for Oxides of Nitrogen and Oxides of Sulfur: First External Review Draft (75 FR 11877; March 12, 2010... a proposal addressing the nitrogen oxides (NO X ) and sulfur oxides (SO X ) secondary National...

  4. An engineered polypeptide around nano-sized manganese-calcium oxide: copying plants for water oxidation.

    Science.gov (United States)

    Najafpour, Mohammad Mahdi; Ghobadi, Mohadeseh Zarei; Sarvi, Bahram; Haghighi, Behzad

    2015-09-14

    Synthesis of new efficient catalysts inspired by Nature is a key goal in the production of clean fuel. Different compounds based on manganese oxide have been investigated in order to find their water-oxidation activity. Herein, we introduce a novel engineered polypeptide containing tyrosine around nano-sized manganese-calcium oxide, which was shown to be a highly active catalyst toward water oxidation at low overpotential (240 mV), with high turnover frequency of 1.5 × 10(-2) s(-1) at pH = 6.3 in the Mn(III)/Mn(IV) oxidation range. The compound is a novel structural and efficient functional model for the water-oxidizing complex in Photosystem II. A new proposed clever strategy used by Nature in water oxidation is also discussed. The new model of the water-oxidizing complex opens a new perspective for synthesis of efficient water-oxidation catalysts.

  5. A Self-Consistent Model for Thermal Oxidation of Silicon at Low Oxide Thickness

    Directory of Open Access Journals (Sweden)

    Gerald Gerlach

    2016-01-01

    Full Text Available Thermal oxidation of silicon belongs to the most decisive steps in microelectronic fabrication because it allows creating electrically insulating areas which enclose electrically conductive devices and device areas, respectively. Deal and Grove developed the first model (DG-model for the thermal oxidation of silicon describing the oxide thickness versus oxidation time relationship with very good agreement for oxide thicknesses of more than 23 nm. Their approach named as general relationship is the basis of many similar investigations. However, measurement results show that the DG-model does not apply to very thin oxides in the range of a few nm. Additionally, it is inherently not self-consistent. The aim of this paper is to develop a self-consistent model that is based on the continuity equation instead of Fick’s law as the DG-model is. As literature data show, the relationship between silicon oxide thickness and oxidation time is governed—down to oxide thicknesses of just a few nm—by a power-of-time law. Given by the time-independent surface concentration of oxidants at the oxide surface, Fickian diffusion seems to be neglectable for oxidant migration. The oxidant flux has been revealed to be carried by non-Fickian flux processes depending on sites being able to lodge dopants (oxidants, the so-called DOCC-sites, as well as on the dopant jump rate.

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

    Science.gov (United States)

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

    2012-01-01

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

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

    Science.gov (United States)

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

    2012-01-01

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

  8. Control of bovine hepatic fatty acid oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Jesse, B.W.; Emery, R.S.; Thomas, J.W.

    1986-09-01

    Fatty acid oxidation by bovine liver slices and mitochondria was examined to determine potential regulatory sites of fatty acid oxidation. Conversion of 1-(/sup 14/C)palmitate to /sup 14/CO/sub 2/ and total (/sup 14/C)acid-soluble metabolites was used to measure fatty acid oxidation. Oxidation of palmitate (1 mM) was linear in both liver slice weight and incubation time. Carnitine stimulated palmitate oxidation; 2 mM dl-carnitine produced maximal stimulation of palmitate oxidation to both CO/sup 2/ and acid-soluble metabolites. Propionate (10 mM) inhibited palmitate oxidation by bovine liver slices. Propionate (.5 to 10 mM) had no effect on palmitate oxidation by mitochondria, but malonyl Coenzyme A, the first committed intermediate of fatty acid synthesis, inhibited mitochondrial palmitate oxidation (inhibition constant = .3 ..mu..M). Liver mitochonndrial carnitine palmitoyltransferase exhibited Michaelis constants for palmitoyl Coenzyme A and l-carnitine of 11.5 ..mu..M and .59 mM, respectively. Long-chain fatty acid oxidation in bovine liver is regulated by mechanisms similar to those in rats but adapted to the unique digestive physiology of the bovine.

  9. Protein oxidation in aging and the removal of oxidized proteins.

    Science.gov (United States)

    Höhn, Annika; König, Jeannette; Grune, Tilman

    2013-10-30

    Reactive oxygen species (ROS) are generated constantly within cells at low concentrations even under physiological conditions. During aging the levels of ROS can increase due to a limited capacity of antioxidant systems and repair mechanisms. Proteins are among the main targets for oxidants due to their high rate constants for several reactions with ROS and their abundance in biological systems. Protein damage has an important influence on cellular viability since most protein damage is non-repairable, and has deleterious consequences on protein structure and function. In addition, damaged and modified proteins can form cross-links and provide a basis for many senescence-associated alterations and may contribute to a range of human pathologies. Two proteolytic systems are responsible to ensure the maintenance of cellular functions: the proteasomal (UPS) and the lysosomal system. Those degrading systems provide a last line of antioxidative protection, removing irreversible damaged proteins and recycling amino acids for the continuous protein synthesis. But during aging, both systems are affected and their proteolytic activity declines significantly. Here we highlight the recent advantages in the understanding of protein oxidation and the fate of these damaged proteins during aging. This article is part of a Special Issue entitled: Posttranslational Protein modifications in biology and Medicine. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Greenlighting Photoelectrochemical Oxidation of Water by Iron Oxide

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Wook; Riha, Shannon C.; DeMarco, Erica J.; Martinson, Alex B. F.; Farha, Omar K.; Hupp, Joseph T.

    2014-12-23

    Hematite (alpha-Fe2O3) is one of just a few candidate electrode materials that possess all of the following photocatalyst-essential properties for scalable application to water oxidation: excellent stability, earth-abundance, suitability positive valence-band-edge energy, and significant visible light absorptivity. Despite these merits, hematites modest oxygen evolution reaction kinetics and its poor efficiency in delivering photogenerated holes, especially holes generated by green photons, to the electrode/solution interface, render it ineffective as a practical water-splitting catalyst. Here we show that hole delivery and catalytic utilization can be substantially improved through Ti alloying, provided that the alloyed material is present in ultrathin-thin-film form. Notably, the effects are most pronounced for charges photogenerated by photons with energy comparable to the band gap for excitation of Fe(3d) -> Fe(3d) transitions (i.e., green photons). Additionally, at the optimum Ti substitution level the lifetimes of surface-localized holes, competent for water oxidation, are extended. Together these changes explain an overall improvement in photoelectrochemical performance, especially enhanced internal quantum efficiencies, observed upon Ti(IV) incorporation.

  11. Oxidative and Non-Oxidative Metabolomics of Ethanol.

    Science.gov (United States)

    Dinis-Oliveira, Ricardo Jorge

    2016-01-01

    It is well known that ethanol can cause significant morbidity and mortality, and much of the related toxic effects can be explained by its metabolic profile. This work performs a complete review of the metabolism of ethanol focusing on both major and minor metabolites. An exhaustive literature search was carried out using textual and structural queries for ethanol and related known metabolizing enzymes and metabolites. The main pathway of metabolism is catalyzed by cytosolic alcohol dehydrogenase, which exhibits multiple isoenzymes and genetic polymorphisms with clinical and forensic implications. Another two oxidative routes, the highly inducible CYP2E1 system and peroxisomal catalase may acquire relevance under specific circumstances. In addition to oxidative metabolism, ethanol also originates minor metabolites such as ethyl glucuronide, ethyl sulfate, ethyl phosphate, ethyl nitrite, phosphatidylethanol and fatty acid ethyl esters. These metabolites represent alternative biomarkers since they can be detected several hours or days after ethanol exposure. It is expected that knowing the metabolomics of ethanol may provide additional insights to better understand the toxicological effects and the variability of dose response.

  12. Simulation of 3D mesoscale structure formation in concentrated aqueous solution of the triblock polymer surfactants (ethylene oxide)(13)(propylene oxide)(30)(ethylene oxide)(13) and (propylene oxide)(19)(ethylene oxide)(33)(propylene oxide)(19). Application of dynamic mean-field density functional theory

    NARCIS (Netherlands)

    van Vlimmeren, BAC; Maurits, NM; Zvelindovsky, AV; Sevink, GJA; Fraaije, JGEM

    1999-01-01

    We simulate the microphase separation dynamics of aqueous solutions of the triblock polymer surfactants (ethylene oxide)(13)(propylene oxide)(30)(ethylene oxide)(13) and (propylene oxide)(19)(ethylene oxide)(33)(propylene oxide)(19) by a dynamic variant of mean-field density functional theory for

  13. Nickel mobilization in a groundwater well field: Release by pyrite oxidation and desorption from manganese oxides

    DEFF Research Database (Denmark)

    Postma, Dieke; Larsen, Flemming

    1997-01-01

    is furthermore characterized by enhanced Mn2+ concentrations. Apparently nickel accumulates on manganese oxides during pyrite oxidation. When the water table rises again, partially oxidized pyritic layers are resubmerged, and due to an insufficient supply of oxygen, the oxidation of Fe2+ released during pyrite...... oxidation becomes incomplete. The mobilized Fe2+ may reduce manganese oxides and thereby release large amounts of Ni2+ to the groundwater. Calculations using a surface complexation model indicate retardation of nickel to be strongly affected by bulk water composition. At the background groundwater...

  14. Chromium(iii) oxidation by biogenic manganese oxides with varying structural ripening.

    Science.gov (United States)

    Tang, Yuanzhi; Webb, Samuel M; Estes, Emily R; Hansel, Colleen M

    2014-09-20

    Manganese (Mn) oxides, which are generally considered biogenic in origin within natural systems, are the only oxidants of Cr(iii) under typical environmental conditions. Yet the influence of Mn biooxide mineral structural evolution on Cr(iii) oxidation under varying geochemical conditions is unknown. In this study we examined the role of light, organic carbon, pH, and the structure of biogenic Mn oxides on Cr(iii) oxidation. Aging of Mn oxides produced by a marine bacterium within the widespread Roseobacter clade resulted in structural ripening from a colloidal hexagonal to a particulate triclinic birnessite phase. The structurally diverse Mn oxides were then reacted with aqueous Cr(iii) within artificial seawater in the presence or absence of carbon and light. Here we found that Cr(iii) oxidation capacity was highest at near neutral pH and in the combined presence of carbon and light. Mn oxide ripening from a hexagonal to a triclinic birnessite phase led to decreased Cr(iii) oxidation in the presence of carbon and light, whereas no change in reactivity was observed in the absence of carbon and/or in the dark. As only minimal Cr(iii) oxidation was observed in the absence of Mn oxides, these results strongly point to coupled Mn oxide- and photo-induced generation of organic and/or oxygen radicals involved in Cr(iii) oxidation. Based on Mn oxide concentration and structural trends, we postulate that Mn(ii) produced from the oxidation of Cr(iii) by the primary Mn oxide is recycled in the presence of organics and light conditions, (re)generating secondary hexagonal birnessite and thereby allowing for continuous oxidation of Cr(iii). In the absence of this Mn oxide regeneration, Cr(iii) induced structural ripening of the hexagonal birnessite precludes further Cr(iii) oxidation. These results highlight the complexity of reactions involved in Mn oxide mediated Cr(iii) oxidation and suggest that photochemical carbon reactions are requisite for sustained Cr(iii) oxidation

  15. The mechanism of water oxidation catalyzed by nanolayered manganese oxides: New insights.

    Science.gov (United States)

    Najafpour, Mohammad Mahdi; Abbasi Isaloo, Mohsen

    2015-11-01

    Herein we consider the mechanism of water oxidation by nanolayered manganese oxide in the presence of cerium(IV) ammonium nitrate. Based on membrane-inlet mass spectrometry results, the rate of H2((18))O exchange of μ-O groups on the surface of the nanolayered Mn-K oxide, and studies on water oxidation in the presence of different ratios of acetonitrile/water we propose a mechanism for water oxidation by nanolayered Mn oxides in the presence of cerium(IV) ammonium nitrate. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Nitric oxide and hypoxia signaling.

    Science.gov (United States)

    Jeffrey Man, H S; Tsui, Albert K Y; Marsden, Philip A

    2014-01-01

    Nitric oxide (NO) production is catalyzed by three distinct enzymes, namely, neuronal nitric oxide synthase (nNOS), inducible NOS (iNOS), and endothelial NOS (eNOS). The production of NO by vascular endothelium relies mainly on eNOS. Curiously, iNOS and nNOS also are relevant for vascular NO production in certain settings. By relaxing vascular smooth muscle, the classical view is that NO participates in O2 homeostasis by increasing local blood flow and O2 delivery. It is now appreciated that NO has an even more fundamental role in cellular oxygen sensing at the cellular and physiological level. A key component of cellular oxygen sensing is the hypoxia-inducible factor (HIF) that activates a transcriptional program to promote cellular survival under conditions of inadequate oxygen supply. Important new insights demonstrate that HIF protein is stabilized by two parallel pathways: (1) a decrease in the O2-dependent prolyl hydroxylation of HIF and (2) NO-dependent S-nitrosylation of HIF pathway components including HIF-α. The need for these two complementary pathways to HIF activation arises because decreased oxygen delivery can occur not only by decreased ambient oxygen but also by decreased blood oxygen-carrying capacity, as with anemia. In turn, NO production is tightly linked to O2 homeostasis. O2 is a key substrate for the generation of NO and impacts the enzymatic activity and expression of the enzymes that catalyze the production of NO, the nitric oxide synthases. These relationships manifest in a variety of clinical settings ranging from the unique situation of humans living in hypoxic environments at high altitudes to the common scenario of anemia and the use of therapeutics that can bind or release NO. © 2014 Elsevier Inc. All rights reserved.

  17. Bystander signaling via oxidative metabolism

    Directory of Open Access Journals (Sweden)

    Sawal HA

    2017-08-01

    Full Text Available Humaira Aziz Sawal,1 Kashif Asghar,2 Matthias Bureik,3 Nasir Jalal4 1Healthcare Biotechnology Department, Atta-ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Islamabad, 2Basic Sciences Research, Shaukat Khanum Memorial Cancer Hospital and Research Centre, Lahore, Pakistan; 3Health Science Platform, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, China; 4Health Science Platform, Department of Molecular and Cellular Pharmacology, Tianjin University, Tianjin, China Abstract: The radiation-induced bystander effect (RIBE is the initiation of biological end points in cells (bystander cells that are not directly traversed by an incident-radiation track, but are in close proximity to cells that are receiving the radiation. RIBE has been indicted of causing DNA damage via oxidative stress, besides causing direct damage, inducing tumorigenesis, producing micronuclei, and causing apoptosis. RIBE is regulated by signaling proteins that are either endogenous or secreted by cells as a means of communication between cells, and can activate intracellular or intercellular oxidative metabolism that can further trigger signaling pathways of inflammation. Bystander signals can pass through gap junctions in attached cell lines, while the suspended cell lines transmit these signals via hormones and soluble proteins. This review provides the background information on how reactive oxygen species (ROS act as bystander signals. Although ROS have a very short half-life and have a nanometer-scale sphere of influence, the wide variety of ROS produced via various sources can exert a cumulative effect, not only in forming DNA adducts but also setting up signaling pathways of inflammation, apoptosis, cell-cycle arrest, aging, and even tumorigenesis. This review outlines the sources of the bystander effect linked to ROS in a cell, and provides methods of investigation for researchers who would like to

  18. Oxidative Stress in Cystinosis Patients

    Directory of Open Access Journals (Sweden)

    Maria Helena Vaisbich

    2011-09-01

    Full Text Available Background/Aims: Nephropathic cystinosis (NC is a severe systemic disease and cysteamine improves its prognosis. Lysosomal cystine accumulation is the hallmark of cystinosis and is regarded as the primary defect due to mutations in the CTNS gene. However, there is great evidence that cystine accumulation itself is not responsible for all abnormalities observed in NC. Studies have demonstrated altered ATP metabolism, increased apoptosis, and cell oxidation. An increased number of autophagosomes and autophagic vacuoles have been observed in cystinotic fibroblasts and renal epithelial cells, suggesting that altered autophagy plays a role in NC, leading to increased production of reactive oxygen species. Therefore, cystinosis patients can be more susceptible to oxidative stress (OS and it can contribute to the progression of the renal disease. Our goal was to evaluate a marker of OS (serum TBARS in NC children, and to compare the results with those observed in healthy controls and correlated with renal function parameters. Methods: The study included patients aged under 18 years, with good adherence to the treatment and out of renal replacement therapy. The following parameters were evaluated: serum creatinine, BUN, creatinine clearance estimated by stature and serum TBARS levels. Results: We selected 20 patients aged 8.0 ±3.6 years and observed serum TBARS levels of 4.03 ±1.02 nmol/ml. Serum TBARS levels in the 43 healthy controls, aged 7.4 ±1.1 years, were 1.60 ±0.04 nmol/ml. There was a significant difference between the plasma TBARS levels among the 2 groups (p Conclusion: An increased level of serum TBARS in patients with NC was observed and this abnormality was not correlated with the renal function status degree. This is the first report that shows increased oxidative stress in serum of NC patients.

  19. Magnetostructural coupling in spinel oxides

    Science.gov (United States)

    Kemei, Moureen

    2015-03-01

    Spinels oxides are of great interest functionally as multiferroic, battery, and magnetic materials as well as fundamentally because they exhibit novel spin, structural, and orbital ground states. Competing interactions are at the heart of novel functional behavior in spinels. Here, we explore the intricate landscape of spin, lattice, and orbital interactions in magnetic spinels by employing variable-temperature high-resolution synchrotron x-ray powder diffraction, total neutron scattering, magnetic susceptibility, dielectric, and heat capacity measurements. We show that the onset of long-range magnetic interactions often gives rise to lattice distortions. Our work illustrates that the spinels NiCr2O4, CuCr2O4,andMn3O4, which are tetragonal at room temperature due to Jahn-Teller ordering, undergo further spin-driven structural distortions at the onset of long-range ferrimagnetic order. We have also studied the complete structural description of the ground states of several spinels including the geometrically frustrated spinels ZnCr2O4andMgCr2O4. The detailed spin-lattice studies of spinel oxides presented here illustrate the prevalence of structural phase coexistence when magnetostructural changes occur below 50 K. The new understanding of structural ground states in spinel oxides will guide the design of structure-property relationships in these materials. Broadly, this work highlights the importance of variable-temperature high-resolution synchrotron x-ray diffraction in understanding phase transitions in functional materials. Schlumberger Foundation Faculty for the Future fellowship, MRL Facilities funded by the NSF under Award No. DMR 1121053, and the Advanced Photon Source supported by the DOE, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

  20. Oxidative stress in androgenetic alopecia.

    Science.gov (United States)

    Prie, B E; Iosif, L; Tivig, I; Stoian, I; Giurcaneanu, C

    2016-01-01

    Rationale: Androgenetic alopecia is not considered a life threatening disease but can have serious impacts on the patient's psychosocial life. Genetic, hormonal, and environmental factors are considered responsible for the presence of androgenetic alopecia. Recent literature reports have proved the presence of inflammation and also of oxidative stress at the level of dermal papilla cells of patients with androgenetic alopecia Objective: We have considered of interest to measure the oxidative stress parameters in the blood of patients with androgenetic alopecia Methods and results: 27 patients with androgenetic alopecia and 25 age-matched controls were enrolled in the study. Trolox Equivalent Antioxidant Capacity (TEAC), malondialdehyde (MDA) and total thiols levels were measured on plasma samples. Superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) activities, and also non protein thiols levels together with TEAC activity were determined on erythrocytes samples No statistically significant changes were observed for TEAC erythrocytes, non-protein thiols, GPx and CAT activities. Significantly decreased (palopecia. For plasma samples decreased TEAC activity (palopecia are indicators of oxidative stress presence in these patients. Significantly decreased SOD activity but no change in catalase, glutathione peroxidase, non protein thiols level and total antioxidant activity in erythrocytes are elements which suggest the presence of a compensatory mechanism for SOD dysfunction in red blood cells of patients with androgenetic alopecia. AAG = androgenetic alopecia, MDA = malondialdehyde, SOD = superoxide dismutase, CAT = catalase, GPx = glutathione peroxidase, GSH = glutathione, GST = glutathione transferase, SH = thiols, TEAC = trolox equivalent antioxidant capacity, ABTS = 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid), CDNB = 1-chloro-2,4-dinitrobenzene.

  1. Food processing and lipid oxidation.

    Science.gov (United States)

    German, J B

    1999-01-01

    Food lipids are principally triacylglycerides, phospholipids and sterols found naturally in most biological materials consumed as food and added as functional ingredients in many processed foods. As nutrients, lipids, especially triglycerides, are a concentrated caloric source, provide essential fatty acids and are a solvent and absorption vehicle for fat-soluble vitamins and other nutrients. The presence of fat significantly enhances the organoleptic perception of foods, which partly explains the strong preference and market advantage of fat-rich foods. As a class, lipids contribute many desirable qualities to foods, including attributes of texture, structure, mouthfeel, flavor and color. However, lipids are also one of the most chemically unstable food components and will readily undergo free-radical chain reactions that not only deteriorate the lipids but also: (a) produce oxidative fragments, some of which are volatile and are perceived as the off-flavors of rancidity, (b) degrade proteins, vitamins and pigments and (c) cross-link lipids and other macromolecules into non-nutritive polymers. Free-radical chain reactions are thermodynamically favorable, and as a result, evolutionary selection has strongly influenced the chemistry, metabolism and structure of biological cells to prevent these reactions kinetically. However, the loss of native structure and the death of cells can dramatically accelerate the deteriorative reactions of lipid oxidation. The effects of all processing steps, including raw product selection, harvesting, storage, refining, manufacturing and distribution, on the quality of lipids in the final commodity are considerable. Certain key variables now known to influence oxidative processes can be targeted to increase food lipid stability during and after processing. Retention of or addition of exogenous antioxidants is a well-known consideration, but the presence and activity of catalysts, the integrity of tissues and cells, the quantity of

  2. Poly(ethylene oxide) functionalization

    Science.gov (United States)

    Pratt, Russell Clayton

    2014-04-08

    A simple procedure is provided by which the hydroxyl termini of poly(ethylene oxide) can be appended with functional groups to a useful extent by reaction and precipitation. The polymer is dissolved in warmed toluene, treated with an excess of organic base and somewhat less of an excess of a reactive acylating reagent, reacted for several hours, then precipitated in isopropanol so that the product can be isolated as a solid, and salt byproducts are washed away. This procedure enables functionalization of the polymer while not requiring laborious purification steps such as solvent-solvent extraction or dialysis to remove undesirable side products.

  3. Bidirectional reflectance of zinc oxide

    Science.gov (United States)

    Scott, R.

    1973-01-01

    This investigation was undertaken to determine original and useful information about the bidirection reflectance of zinc oxide. The bidirectional reflectance will be studied for the spectra between .25-2.5 microns and the hemisphere above the specimen. The following factors will be considered: (1) surface conditions; (2) specimen preparation; (3) specimen substrate, (4) polarization; (5) depolarization; (6) wavelength; and (7) angles of incident and reflection. The bidirectional reflectance will be checked by experimentally determined angular hemispherical measurements or hemispherical measurements will be used to obtain absolute bidirectional reflectance.

  4. Oxides gets environmentally-friendly

    DEFF Research Database (Denmark)

    Pryds, Nini

    A large amount of thermal energy is available from the waste heat associated with many industrial and social activities of mankind. However, it is difficult to reclaim this heat due to the dispersed nature and relative smallness of its sources. Thermoelectric conversion offers a very promising...... be stable at high temperatures and be composed of nontoxic and low-cost elements, and must be able to be processed and shaped cheaply. Oxides are among the strongest candidate materials for this purpose. This talk provides an overview of the development on such materials at DTU Energy Conversion. In order...

  5. Liver cirrhosis and nitric oxide

    Directory of Open Access Journals (Sweden)

    Yusuf Ergun

    2009-04-01

    Full Text Available Liver cirrhosis is a clinical condition which appears due to various etiologies and basically contains diffuse fibrozis and nodularity. Portal hypertension frequently accompanies this condition and constitutes the complications with negative effects concerning patients mortality and morbidity. For this reason, understanding the pathophysiologies of cirrhosis and portal hypertension is essential for the supplementation of new treatment options. In this review, the role of nitric oxide in the pathophysiologies of fibrosis, cirrhosis and portal hypertension has been discussed. [Archives Medical Review Journal 2009; 18(2.000: 91-131

  6. Oxidative stability of krill oil (Euphausia superba)

    DEFF Research Database (Denmark)

    Lu, Henna Fung Sieng; Jacobsen, Charlotte; Bruheim, I.

    Krill oil has been reported in many studies to have high oxidative stability when evaluated by peroxide value (PV) and anisidine value (AV). However, recent studies have shown that other compounds than primary and secondary oxidation products are formed when krill oil is exposed to oxidative...... conditions. These compounds include Strecker degradation compounds and pyrroles. Some of these compounds may have antioxidative effect. Commercial scale processing of krill prior to extraction may affect the oxidative stability of krill oil. Therefore, the main objective of this study was to compare lipid...... oxidation in krill oil produced in a commercial process and krill oil carefully extracted from frozen krill in the laboratory. Krill oil was incubated at different temperatures (20, 30 and 40 oC) for 1, 2, 3, 4 and 6 weeks, under conditions of constant stirring while being exposed to air. The oxidative...

  7. Primary atmospheric oxidation mechanism for toluene.

    Science.gov (United States)

    Baltaretu, Cristian O; Lichtman, Eben I; Hadler, Amelia B; Elrod, Matthew J

    2009-01-08

    The products of the primary OH-initiated oxidation of toluene were investigated using the turbulent flow chemical ionization mass spectrometry technique at temperatures ranging from 228 to 298 K. A major dienedial-producing pathway was detected for the first time for toluene oxidation, and glyoxal and methylglyoxal were found to be minor primary oxidation products. The results suggest that secondary oxidation processes involving dienedial and epoxide primary products are likely responsible for previous observations of glyoxal and methylglyoxal products from toluene oxidation. Because the dienedial-producing pathway is a null cycle for tropospheric ozone production and glyoxal and methylglyoxal are important secondary organic aerosol precursors, these new findings have important implications for the modeling of toluene oxidation in the atmosphere.

  8. Applications of Oxide Coatings in Photovoltaic Devices

    Directory of Open Access Journals (Sweden)

    Sonya Calnan

    2014-03-01

    Full Text Available Metalloid and metal based oxides are an almost unavoidable component in the majority of solar cell technologies used at the time of writing this review. Numerous studies have shown increases of ≥1% absolute in solar cell efficiency by simply substituting a given layer in the material stack with an oxide. Depending on the stoichiometry and whether other elements are present, oxides can be used for the purpose of light management, passivation of electrical defects, photo-carrier generation, charge separation, and charge transport in a solar cell. In this review, the most commonly used oxides whose benefits for solar cells have been proven both in a laboratory and industrial environment are discussed. Additionally, developing trends in the use of oxides, as well as newer oxide materials, and deposition technologies for solar cells are reported.

  9. d° Ferromagnetism of Magnesium Oxide

    Directory of Open Access Journals (Sweden)

    Jitendra Pal Singh

    2017-11-01

    Full Text Available Magnetism without d-orbital electrons seems to be unrealistic; however, recent observations of magnetism in non-magnetic oxides, such as ZnO, HfO2, and MgO, have opened new avenues in the field of magnetism. Magnetism exhibited by these oxides is known as d° ferromagnetism, as these oxides either have completely filled or unfilled d-/f-orbitals. This magnetism is believed to occur due to polarization induced by p-orbitals. Magnetic polarization in these oxides arises due to vacancies, the excitation of trapped spin in the triplet state. The presence of vacancies at the surface and subsurface also affects the magnetic behavior of these oxides. In the present review, origins of magnetism in magnesium oxide are discussed to obtain understanding of d° ferromagnetism.

  10. Oxidized mitochondrial protein degradation and repair in aging and oxidative stress.

    Science.gov (United States)

    Ugarte, Nicolas; Petropoulos, Isabelle; Friguet, Bertrand

    2010-08-15

    Proteins are main targets for oxidative damage that occurs during aging and in oxidative stress situations. Since the mitochondria is a major source of reactive oxygen species, mitochondrial proteins are especially exposed to oxidative modification, and elimination of oxidized proteins is crucial for maintaining the integrity of this organelle. Hence, enzymatic reversal of protein oxidation and protein degradation is critical for protein homeostasis while protein maintenance failure has been implicated in the age-related accumulation of oxidized proteins. Within the mitochondrial matrix, the ATP-stimulated mitochondrial Lon protease is believed to play an important role in the degradation of oxidized protein, and age-associated impairment of Lon-like protease activity has been suggested to contribute to oxidized protein buildup in the mitochondria. Oxidized protein repair is limited to certain oxidation products of the sulfur-containing amino acids cysteine and methionine. Oxidized protein repair systems, thioredoxin/thioredoxin reductase or glutaredoxin/glutathione/glutathione reductase that catalytically reduce disulfide bridges or sulfenic acids, and methionine sulfoxide reductase that reverses methionine sulfoxide back to methionine within proteins, are present in the mitochondrial matrix. Thus, the role of the mitochondrial Lon protease and the oxidized protein repair system methionine sulfoxide reductase is further addressed in the context of oxidative stress and aging.

  11. Consumption of oxidized oil increases oxidative stress in broilers and affects the quality of breast meat.

    Science.gov (United States)

    Zhang, Wangang; Xiao, Shan; Lee, Eun Joo; Ahn, Dong U

    2011-02-09

    A total of 120 4-week-old broiler chickens were allotted to 12 pens and fed one of three diets including control, oxidized diet (5% oxidized oil), or antioxidant-added diet (500 IU vitamin E) for 2 weeks. Blood samples were collected at the end of feeding trial, and breast muscles were sampled immediately after slaughter. Breast meats were also collected 24 h after slaughter and used for meat quality measurements. Oxidative stress in blood, lipid and protein oxidation, and sarcoplasmic reticulum Ca²(+)-ATPase (SERCA) activity of breast muscle were determined. The oxidized diet increased oxidative stress in blood and increased carbonyl content in breast meat compared with the other two dietary treatments (P Meat from birds fed the oxidized diet showed higher drip loss after 1 and 3 days of storage and greater 0-1 h post-mortem pH decline (P < 0.05). Significant differences in specific SERCA activity in breast muscles from birds fed control and oxidized diets (P < 0.05) were detected. This suggested that dietary oxidized oil induced oxidative stress in live birds and increased lipid and protein oxidation in breast muscle. Decrease in SERCA activity in breast muscles due to oxidative stress in live animals accelerated post-mortem glycolysis, which sped the pH drop after slaughter and increased drip loss, indicating that oxidation of diet can cause PSE-like (pale, soft, and exudative) conditions in broiler breast muscles.

  12. Gas transport in solid oxide fuel cells

    CERN Document Server

    He, Weidong; Dickerson, James

    2014-01-01

    This book provides a comprehensive overview of contemporary research and emerging measurement technologies associated with gas transport in solid oxide fuel cells. Within these pages, an introduction to the concept of gas diffusion in solid oxide fuel cells is presented. This book also discusses the history and underlying fundamental mechanisms of gas diffusion in solid oxide fuel cells, general theoretical mathematical models for gas diffusion, and traditional and advanced techniques for gas diffusivity measurement.

  13. Oxidation catalysts on alkaline earth supports

    Science.gov (United States)

    Mohajeri, Nahid

    2017-03-21

    An oxidation catalyst includes a support including particles of an alkaline earth salt, and first particles including a palladium compound on the support. The oxidation catalyst can also include precious metal group (PMG) metal particles in addition to the first particles intermixed together on the support. A gas permeable polymer that provides a continuous phase can completely encapsulate the particles and the support. The oxidation catalyst may be used as a gas sensor, where the first particles are chemochromic particles.

  14. Oxidation as ?The Stress of Life?

    OpenAIRE

    Malinin, Nikolay L.; West, Xiaoxia Z.; Byzova, Tatiana V.

    2011-01-01

    Multiple biological consequences of oxidative stress are known to contribute to aging and aging-related pathologies. It was recently shown that (carboxyalkyl)pyrroles (CAPs), the end products of phospholipid oxidation serve as a novel class of endogenous ligands for Toll-like receptors (TLRs) and promote the process of angiogenesis. In this review, we discuss implications of these findings in the context of age-related pathologies, including tumorigenesis. Accumulation of oxidation products i...

  15. A STUDY OF OXIDATIVE STRESS IN DIABETES

    OpenAIRE

    Babu Rao; Santhoshi; Sridhar V; Souris; Margaret

    2015-01-01

    Non - enzymatic free radical mediated oxidation of biological molecules, membranes and tissues is associated with a variety of pathological events such as cancer, aging and diabetes mellitus . [1] Increased oxidative stress is seen in both types of diabetes me llitus namely type 1 and type 2, irrespective of duration, complications and treatment. In diabetes mellitus, oxidative stress seems primarily due to both an increased plasma free radical concentra...

  16. Impact of Oxidative Stress in Fetal Programming

    OpenAIRE

    Thompson, Loren P.; Yazan Al-Hasan

    2012-01-01

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

  17. Atomic-level mechanisms of magnesium oxidation

    OpenAIRE

    Gardonio, Sandra; Fanetti, Mattia; Valant, Matjaž; Orlov, Dmytro

    2017-01-01

    Magnesium has been recently becoming an increasingly popular material for various applications. However, excessive chemical reactivity, and oxidation rate in particular, is a major obstruction on the way of Mg to become widely adopted. A significant problem causing the lack of Mg reactivity control is insufficient understanding of mechanisms involved in the oxidation of magnesium surface. Herewith we present the investigation of atomic-level mechanisms of oxidation initiation and propagation ...

  18. Superlubricating graphene and graphene oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Sumant, Anirudha V.; Erdemir, Ali; Choi, Junho; Berman, Diana

    2018-02-13

    A system and method for forming at least one of graphene and graphene oxide on a substrate and an opposed wear member. The system includes graphene and graphene oxide formed by an exfoliation process or solution processing method to dispose graphene and/or graphene oxide onto a substrate. The system further includes an opposing wear member disposed on another substrate and a gas atmosphere of an inert gas like N2, ambient, a humid atmosphere and a water solution.

  19. PROCESSES OF CHLORINATION OF URANIUM OXIDES

    Science.gov (United States)

    Rosenfeld, S.

    1958-09-16

    An improvement is described in the process fur making UCl/sub 4/ from uranium oxide and carbon tetrachloride. In that process, oxides of uranium are contacted with carbon tetrachloride vapor at an elevated temperature. It has been fuund that the reaction product and yield are improved if the uranlum oxide charge is disposed in flat trays in the reaction zone, to a depth of not more than 1/2 centimeter.

  20. Chemical oxidation-enhanced bioremediation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, B.; Kelley, B.; Paterek, B.; Srivastava, V. [Institute of Gas Technology, Des Plaines, IL (United States)

    1995-12-31

    The Institute of Gas Technology (IGT) has developed and demonstrated a cost-effective soil remediation technology for contaminants present at the former manufactured gas plant (MGP) sites. The technology is known as the MGP-REM process. This process is based on the enhancement and acceleration of indigenous biological activity and the application of chemical treatment to promote subsequent biological degradation of the chemically modified compounds. The chemical treatment uses hydrogen peroxide and iron salt (Fenton`s Reagent) as an oxidant to oxidize polynuclear aromatic hydrocarbons (PAHs), making them more amenable to biological treatment, The MGP-REM process is faster and achieves a higher degree of cleanup than the conventional biological process alone, costs no more than conventional bioremediation, and is much cheaper than incineration. This integrated chemical/biological treatment can be applied to other contaminants such as PCBs and cyanide. The major benefit of this process is its ability to degrade those hard-to-degrade compounds without generating any harmful by-products. The treatment end-products of this process are carbon dioxide and water. IGT has successfully field tested this technology in landfarming mode between 1991 and 1993, and in soil-bioslurry mode during 1993-1994. ln-situ field tests are expected to start in 1995.

  1. Etiologies of sperm oxidative stress

    Directory of Open Access Journals (Sweden)

    Parvin Sabeti

    2016-04-01

    Full Text Available Sperm is particularly susceptible to reactive oxygen species (ROS during critical phases of spermiogenesis. However, the level of seminal ROS is restricted by seminal antioxidants which have beneficial effects on sperm parameters and developmental potentials. Mitochondria and sperm plasma membrane are two major sites of ROS generation in sperm cells. Besides, leukocytes including polymer phonuclear (PMN leukocytes and macrophages produce broad category of molecules including oxygen free radicals, non-radical species and reactive nitrogen species. Physiological role of ROS increase the intracellular cAMP which then activate protein kinase in male reproductive system. This indicates that spermatozoa need small amounts of ROS to acquire the ability of nuclear maturation regulation and condensation to fertilize the oocyte. There is a long list of intrinsic and extrinsic factors which can induce oxidative stress to interact with lipids, proteins and DNA molecules. As a result, we have lipid peroxidation, DNA fragmentation, axonemal damage, denaturation of the enzymes, over generation of superoxide in the mitochondria, lower antioxidant activity and finally abnormal spermatogenesis. If oxidative stress is considered as one of the main cause of DNA damage in the germ cells, then there should be good reason for antioxidant therapy in these conditions

  2. Oxidative stress in endometrial hyperplasia.

    Science.gov (United States)

    Gómez-Zubeldia, María Angeles; Bazo, Ascensión Pérez; Gabarre, Juan José Arbués; Nogales, Agustín García; Palomino, José Carlos Millán

    2008-01-01

    Reactive oxygen species seem to be involved in the onset and promotion of carcinogenesis. In 80% of cases of endometrial adenocarcinoma type I, a clear association exists with endometrial hyperplasia, which is considered a key factor in the endometrial oncological spectrum. The presence or absence of atypical cells determines oncological potential. This study explored the behavior of oxidative stress (catalase and malondialdehyde) in endometrial hyperplasia (with or without atypical cells) by comparing it with the oxidative stress existing in both the proliferative and secretory phases. Endometrial specimens from 55 women were used, 32 of which were histologically diagnosed as physiological (17 proliferative and 15 secretory endometria) and 23 as endometrial hyperplasia (18 nonatypical and 5 atypical endometrial hyperplasia). Significant differences were found in the malondialdehyde variable between the proliferative endometrium and the endometrium with atypical hyperplasia (P = 0.0208) and between both types of endometrial hyperplasia (P = 0.0441). The other comparisons were not statistically significant. No changes in catalase activity were observed. Our findings seem to suggest that the presence of atypical cells in endometrial hyperplasia induces a reduction in lipid peroxidation, which could permit survival and growth of these cells. This possible decrease in lipid peroxidation does not seem to be mediated by an increase in endometrial catalase activity.

  3. Lung Oxidative Damage by Hypoxia

    Directory of Open Access Journals (Sweden)

    O. F. Araneda

    2012-01-01

    Full Text Available One of the most important functions of lungs is to maintain an adequate oxygenation in the organism. This organ can be affected by hypoxia facing both physiological and pathological situations. Exposure to this condition favors the increase of reactive oxygen species from mitochondria, as from NADPH oxidase, xanthine oxidase/reductase, and nitric oxide synthase enzymes, as well as establishing an inflammatory process. In lungs, hypoxia also modifies the levels of antioxidant substances causing pulmonary oxidative damage. Imbalance of redox state in lungs induced by hypoxia has been suggested as a participant in the changes observed in lung function in the hypoxic context, such as hypoxic vasoconstriction and pulmonary edema, in addition to vascular remodeling and chronic pulmonary hypertension. In this work, experimental evidence that shows the implied mechanisms in pulmonary redox state by hypoxia is reviewed. Herein, studies of cultures of different lung cells and complete isolated lung and tests conducted in vivo in the different forms of hypoxia, conducted in both animal models and humans, are described.

  4. Oxidative Stress and Diabetic Retinopathy

    Directory of Open Access Journals (Sweden)

    Renu A. Kowluru

    2007-01-01

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

  5. Advanced oxidation scanning probe lithography

    Science.gov (United States)

    Ryu, Yu K.; Garcia, Ricardo

    2017-04-01

    Force microscopy enables a variety of approaches to manipulate and/or modify surfaces. Few of those methods have evolved into advanced probe-based lithographies. Oxidation scanning probe lithography (o-SPL) is the only lithography that enables the direct and resist-less nanoscale patterning of a large variety of materials, from metals to semiconductors; from self-assembled monolayers to biomolecules. Oxidation SPL has also been applied to develop sophisticated electronic and nanomechanical devices such as quantum dots, quantum point contacts, nanowire transistors or mechanical resonators. Here, we review the principles, instrumentation aspects and some device applications of o-SPL. Our focus is to provide a balanced view of the method that introduces the key steps in its evolution, provides some detailed explanations on its fundamentals and presents current trends and applications. To illustrate the capabilities and potential of o-SPL as an alternative lithography we have favored the most recent and updated contributions in nanopatterning and device fabrication.

  6. Cerium oxide nanoparticles in cancer

    Directory of Open Access Journals (Sweden)

    Gao Y

    2014-05-01

    Full Text Available Ying Gao,1 Kan Chen,2,* Jin-lu Ma,1,* Fei Gao3 1Department of Radiotherapy Oncology, First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an, People's Republic of China; 2School of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, People's Republic of China; 3Department of Neurology, First Affiliated Hospital of Xi'an Medical University, Xi'an, People's Republic of China *These authors contributed equally to this work Abstract: With the development of many nanomedicines designed for tumor therapy, the diverse abilities of cerium oxide nanoparticles (CONPs have encouraged researchers to pursue CONPs as a therapeutic agent to treat cancer. Research data have shown CONPs to be toxic to cancer cells, to inhibit invasion, and to sensitize cancer cells to radiation therapy and chemotherapy. CONPs also display minimal toxicity to normal tissues and provide protection from various forms of reactive oxygen species generation. Differential cytotoxicity is important for anticancer drugs to distinguish effectively between tumor cells and normal cells. The antioxidant capabilities of CONPs, which enable cancer therapy protection, have also resulted in the exploration of these particles as a potential anticancer treatment. Taken together, CONPs might be a potential nanomedicine for cancer therapy and this review highlights the current research into CONPs as a novel therapeutic for the treatment of cancer. Keywords: cerium oxide nanoparticles, cancer treatment, radioprotection, radiosensitization

  7. Chemically Assisted Photocatalytic Oxidation System

    Science.gov (United States)

    Andino, Jean; Wu, Chang-Yu; Mazyck, David; Teixeira, Arthur A.

    2009-01-01

    The chemically assisted photocatalytic oxidation system (CAPOS) has been proposed for destroying microorganisms and organic chemicals that may be suspended in the air or present on surfaces of an air-handling system that ventilates an indoor environment. The CAPOS would comprise an upstream and a downstream stage that would implement a tandem combination of two partly redundant treatments. In the upstream stage, the air stream and, optionally, surfaces of the air-handling system would be treated with ozone, which would be generated from oxygen in the air by means of an electrical discharge or ultraviolet light. In the second stage, the air laden with ozone and oxidation products from the first stage would be made to flow in contact with a silica-titania photocatalyst exposed to ultraviolet light in the presence of water vapor. Hydroxyl radicals generated by the photocatalytic action would react with both carbon containing chemicals and microorganisms to eventually produce water and carbon dioxide, and ozone from the first stage would be photocatalytically degraded to O2. The net products of the two-stage treatment would be H2O, CO2, and O2.

  8. Bystander signaling via oxidative metabolism.

    Science.gov (United States)

    Sawal, Humaira Aziz; Asghar, Kashif; Bureik, Matthias; Jalal, Nasir

    2017-01-01

    The radiation-induced bystander effect (RIBE) is the initiation of biological end points in cells (bystander cells) that are not directly traversed by an incident-radiation track, but are in close proximity to cells that are receiving the radiation. RIBE has been indicted of causing DNA damage via oxidative stress, besides causing direct damage, inducing tumorigenesis, producing micronuclei, and causing apoptosis. RIBE is regulated by signaling proteins that are either endogenous or secreted by cells as a means of communication between cells, and can activate intracellular or intercellular oxidative metabolism that can further trigger signaling pathways of inflammation. Bystander signals can pass through gap junctions in attached cell lines, while the suspended cell lines transmit these signals via hormones and soluble proteins. This review provides the background information on how reactive oxygen species (ROS) act as bystander signals. Although ROS have a very short half-life and have a nanometer-scale sphere of influence, the wide variety of ROS produced via various sources can exert a cumulative effect, not only in forming DNA adducts but also setting up signaling pathways of inflammation, apoptosis, cell-cycle arrest, aging, and even tumorigenesis. This review outlines the sources of the bystander effect linked to ROS in a cell, and provides methods of investigation for researchers who would like to pursue this field of science.

  9. OXIDATIVE STRESS AND SPERM PATHOLOGIES

    Directory of Open Access Journals (Sweden)

    V. V. Evdokimov

    2017-01-01

    Full Text Available The study objective was to evaluate the level of oxidative stress and antioxidant defense of the ejaculate in different types of sperm pathologies caused by reproductive system disorders including varicocele, idiopathic asthenozoospermia, non-obstructive asthenozoospermia. Patients groups included 14, 11, and 16 men aged 20–45.Methods of ejaculate examination included study of morphological parameters in accordance with the 5th edition of the World Health Organization Guidelines. Biochemical parameters of the spermoplasm were measured according to the standard procedures described in previous articles.The study included men with abnormal sperm motility and morphology in the ejaculate, i. e. men with sperm pathologies in the form of asthenozoospermia. Morphological and biochemical changes were detected in the patient groups with varicocele and with asthenoand azoospermia compared to the normospermia group.In the separate varicocele group, patients were examined before and after varicocelectomy. Morphological parameters of the ejaculate didn’t show significant improvement, but biochemical parameters of the spermoplasm changed significantly: total antioxidant activity increased, the level of superoxide dismutase decreased which demonstrates decreased effect of oxidative stress after varicocelectomy.

  10. Tape casting of magnesium oxide.

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-02-01

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

  11. Water defluoridation by aluminium oxide-manganese oxide composite material.

    Science.gov (United States)

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

    2014-08-01

    In this study, aluminium oxide-manganese oxide (AOMO) composite material was synthesized, characterized, and tested for fluoride removal in batch experiments. AOMO was prepared from manganese(II) chloride and aluminium hydroxide. The surface area of AOMO was found to be 30.7m2/g and its specific density was determined as 2.78 g/cm3. Detailed investigation of the adsorbent by inductively coupled plasma-optical emission spectrometry, inductively coupled plasma-mass spectrometry, and ion chromatography (for sulphate only) showed that it is composed of Al, Mn, SO4, and Na as major components and Fe, Si, Ca, and Mg as minor components. Thermogravimetric analysis was used to study the thermal behaviour of AOMO. X-ray diffraction analysis showed that the adsorbent is poorly crystalline. The point of zero charge was determined as 9.54. Batch experiments (by varying the proportion of MnO, adsorbent dose, contact time, initial F concentration, and raw water pH) showed that fluoride removal efficiency ofAOMO varied significantly with percentage of MnO with an optimum value of about I11% of manganese oxide in the adsorbent. The optimum dose of the adsorbent was 4 g/L which corresponds to the equilibrium adsorption capacity of 4.8 mg F-/g. Both the removal efficiency and adsorption capacity showed an increasing trend with an increase in initial fluoride concentration of the water. The pH for optimum fluoride removal was found to be in the range between 5 and 7. The adsorption data were analysed using the Freundlich, Langmuir, and Dubinirn-Radushkevich models. The minimum adsorption capacity obtained from the non-linear Freundlich isotherm model was 4.94 mg F-/g and the maximum capacity from the Langmuir isotherm method was 19.2mg F-/g. The experimental data of fluoride adsorption on AOMO fitted well to the Freundlich isotherm model. Kinetic studies showed that the adsorption is well described by a non-linear pseudo-second-order reaction model with an average rate constant of 3

  12. AN ADVANCED OXIDATION PROCESS : FENTON PROCESS

    Directory of Open Access Journals (Sweden)

    Engin GÜRTEKİN

    2008-03-01

    Full Text Available Biological wastewater treatment is not effective treatment method if raw wastewater contains toxic and refractory organics. Advanced oxidation processes are applied before or after biological treatment for the detoxification and reclamation of this kind of wastewaters. The advanced oxidation processes are based on the formation of powerful hydroxyl radicals. Among advanced oxidation processes Fenton process is one of the most promising methods. Because application of Fenton process is simple and cost effective and also reaction occurs in a short time period. Fenton process is applied for many different proposes. In this study, Fenton process was evaluated as an advanced oxidation process in wastewater treatment.

  13. Perspective: Oxide molecular-beam epitaxy rocks!

    Directory of Open Access Journals (Sweden)

    Darrell G. Schlom

    2015-06-01

    Full Text Available Molecular-beam epitaxy (MBE is the “gold standard” synthesis technique for preparing semiconductor heterostructures with high purity, high mobility, and exquisite control of layer thickness at the atomic-layer level. Its use for the growth of multicomponent oxides got off to a rocky start 30 yr ago, but in the ensuing decades, it has become the definitive method for the preparation of oxide heterostructures too, particularly when it is desired to explore their intrinsic properties. Examples illustrating the unparalleled achievements of oxide MBE are given; these motivate its expanding use for exploring the potentially revolutionary states of matter possessed by oxide systems.

  14. Oxidation of carbon monoxide by perferrylmyoglobin

    DEFF Research Database (Denmark)

    Libardi, Silvia H; Skibsted, Leif Horsfelt; Cardoso, Daniel R

    2014-01-01

    Perferrylmyoglobin is found to oxidize CO in aerobic aqueous solution to CO2. Tryptophan hydroperoxide in the presence of tetra(4-sulfonatophenyl)-porphyrinate-iron(III) or simple iron(II)/(III) salts shows similar reactivity against CO. The oxidation of CO is for tryptophan hydroperoxide concluded...... to depend on the formation of alkoxyl radicals by reductive cleavage by iron(II) or on the formation of peroxyl radicals by oxidative cleavage by iron(III). During oxidation of CO, the tryptophan peroxyl radical was depleted with a rate constant of 0.26 ± 0.01 s(-1) for CO-saturated aqueous solution of pH 7...

  15. Is the Oxidative Stress Really a Disease?

    Directory of Open Access Journals (Sweden)

    Fogarasi Erzsébet

    2016-03-01

    Full Text Available Oxidative stress is an imbalance between free radicals or other reactive species and the antioxidant activity of the organism. Oxidative stress can induce several illnesses such as cardiovascular disease, neurodegenerative disorders, diabetes, cancer, Alzheimer and Parkinson. The biomarkers of oxidative stress are used to test oxidative injury of biomolecules. The indicators of lipid peroxidation (malondialdehyde, 4-hydroxy- 2-nonenal, 2-propenal, isoprostanes, of protein oxidation (carbonylated proteins, tyrosine derivatives, of oxidative damage of DNA, and other biomarkers (glutathione level, metallothioneins, myeloperoxidase activity are the most used oxidative stress markers. Diseases caused by oxidative stress can be prevented with antioxidants. In human body are several enzymes with antioxidant capacity (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and spin traps. Antioxidants are synthetized in the organism (glutathione or arrive in the body by nutrition (ascorbic acid, vitamin E, carotenoids, flavonoids, resveratrol, xanthones. Different therapeutic strategies to reduce oxidative stress with the use of synthetic molecules such as nitrone-based antioxidants (phenyl-α-tert-butyl-nitrone (PBN, 2,4-disulphophenyl- N-tert-butylnitrone (NXY-059, stilbazulenyl nitrone (STAZN, which scavenge a wide variety of free radical species, increase endogenous antioxidant levels and inhibits free radical generation are also tested in animal models.

  16. A new oxidant for hair coloring.

    Science.gov (United States)

    Marsh, Jennifer; Dahlgren, R Marc; Clarke, Colin; Stonehouse, Jonathan; Nunn, Chris

    2009-01-01

    Coloring hair using a level 3 permanent colorant involves two processes, lightening the underlying melanin and information of the colored chromophores inside the hair. In a typical in-market products the oxidant used to achieve these changes is hydrogen peroxide buffered at pH 10 with an alkalizer such as ammonium hydroxide. A new oxidant has been developed based on the combination of ammonium carbonate, hydrogen peroxide and glycine at pH 9 that can match the lightening and color performance of the current oxidant. It has the advantage that both the carbonate and hydrogen peroxide concentrations can be changed to alter the lightening performance making it a more flexible oxidant. This allows the capability to lighten the hair in a shorter time, or with lower hydrogen peroxide levels. This paper discusses the key oxidizing species that are present in both systems and the mechanisms of melanin lightening. In addition, the lightening performance will be assessed as a function of time, pH, hydrogen peroxide concentration and carbonate concentration. The importance of glycine to the oxidant is also described along with a proposal for its mechanism of action. It has been demonstrated that the addition of glycine can control the undesired formation of carbonate radicals that can be generated from the oxidant. The control of these radicals enables the oxidant to deliver excellent lightening with no negatives in fiber damage bs. conventional oxidants.

  17. Survival responses to oxidative stress and aging.

    Science.gov (United States)

    Miura, Yuri; Endo, Tamao

    2010-07-01

    Oxidative stress is recognized as an important environmental factor in aging; however, because reactive oxygen species (ROS) and related free radicals are normally produced both intra- and extracellularly, air-living organisms cannot avoid the risk of oxidative stress. Consequently, these organisms have evolved various anti-oxidant systems to prevent ROS, scavenge free radicals, repair damaged components and adaptive responses. This review will focus on the repair and adaptive response to oxidative stress, and summarize the changes of these systems as a result aging and their relationship to premature aging.

  18. High Performance Photocatalytic Oxidation Reactor System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Pioneer Astronautics proposes a technology program for the development of an innovative photocatalytic oxidation reactor for the removal and mineralization of...

  19. ADVANCED OXIDATION PROCESSES (AOX) TEXTILE WASTEWATER

    OpenAIRE

    Salas C., G.; Facultad de Química e Ingeniería Química. Universidad Nacional Mayor de San Marcos. Lima - Perú

    2014-01-01

    Advanced Oxidation Processes (AOX) are based on the in situ generation of hydroxyradicals (·OH), which have a high oxidation potential. In the case of Fenton processes !he generation of hydroxy radicals takes place by the combination of an oxidation agent (H202) with a catalyst (Fe(II)). These radicals are not selective and they react very fast with the organic matter,being able to oxidize a high variety of organic compounds. This property allows the degradation of pollutants into more biodeg...

  20. Oxide driven strength evolution of silicon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Grutzik, Scott J.; Zehnder, Alan T., E-mail: atz2@cornell.edu [Field of Theoretical and Applied Mechanics, Cornell University, Ithaca, New York 14853 (United States); Milosevic, Erik [Department of Nanoengineering, SUNY Polytechnic University, Albany, New York 12203 (United States); Boyce, Brad L. [Sandia National Laboratories, Albuquerque, New Mexico 87185-0889 (United States)

    2015-11-21

    Previous experiments have shown a link between oxidation and strength changes in single crystal silicon nanostructures but provided no clues as to the mechanisms leading to this relationship. Using atomic force microscope-based fracture strength experiments, molecular dynamics modeling, and measurement of oxide development with angle resolved x-ray spectroscopy we study the evolution of strength of silicon (111) surfaces as they oxidize and with fully developed oxide layers. We find that strength drops with partial oxidation but recovers when a fully developed oxide is formed and that surfaces intentionally oxidized from the start maintain their high initial strengths. MD simulations show that strength decreases with the height of atomic layer steps on the surface. These results are corroborated by a completely separate line of testing using micro-scale, polysilicon devices, and the slack chain method in which strength recovers over a long period of exposure to the atmosphere. Combining our results with insights from prior experiments we conclude that previously described strength decrease is a result of oxidation induced roughening of an initially flat silicon (1 1 1) surface and that this effect is transient, a result consistent with the observation that surfaces flatten upon full oxidation.

  1. Advanced Wastewater Photo-oxidation System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Pioneer Astronautics proposes an advanced photocatalytic oxidation reactor for enhancing the reliability and performance of Water Recovery Post Processing systems...

  2. Comparison of thermal oxidation and plasma oxidation of 4H-SiC (0001) for surface flattening

    Science.gov (United States)

    Deng, Hui; Endo, Katsuyoshi; Yamamura, Kazuya

    2014-03-01

    The thermal oxidation and water vapor plasma oxidation of 4H-SiC (0001) were investigated. The initial oxidation rate of helium-based atmospheric-pressure plasma oxidation was six times higher than that of thermal oxidation. The oxide-SiC interface generated by plasma oxidation became flatter with increasing thickness of the oxide, whereas the interface generated by thermal oxidation was atomically flat regardless of the oxide thickness. Many pits were generated on the thermally oxidized surface, whereas few pits were observed on the surface oxidized by plasma. After the oxide layer generated plasma oxidation was removed, an atomically flat and pit-free SiC surface was obtained.

  3. Interfacial bonding stabilizes rhodium and rhodium oxide nanoparticles on layered Nb oxide and Ta oxide supports.

    Science.gov (United States)

    Strayer, Megan E; Binz, Jason M; Tanase, Mihaela; Shahri, Seyed Mehdi Kamali; Sharma, Renu; Rioux, Robert M; Mallouk, Thomas E

    2014-04-16

    Metal nanoparticles are commonly supported on metal oxides, but their utility as catalysts is limited by coarsening at high temperatures. Rhodium oxide and rhodium metal nanoparticles on niobate and tantalate supports are anomalously stable. To understand this, the nanoparticle-support interaction was studied by isothermal titration calorimetry (ITC), environmental transmission electron microscopy (ETEM), and synchrotron X-ray absorption and scattering techniques. Nanosheets derived from the layered oxides KCa2Nb3O10, K4Nb6O17, and RbTaO3 were compared as supports to nanosheets of Na-TSM, a synthetic fluoromica (Na0.66Mg2.68(Si3.98Al0.02)O10.02F1.96), and α-Zr(HPO4)2·H2O. High surface area SiO2 and γ-Al2O3 supports were also used for comparison in the ITC experiments. A Born-Haber cycle analysis of ITC data revealed an exothermic interaction between Rh(OH)3 nanoparticles and the layered niobate and tantalate supports, with ΔH values in the range -32 kJ·mol(-1) Rh to -37 kJ·mol(-1) Rh. In contrast, the interaction enthalpy was positive with SiO2 and γ-Al2O3 supports. The strong interfacial bonding in the former case led to "reverse" ripening of micrometer-size Rh(OH)3, which dispersed as 0.5 to 2 nm particles on the niobate and tantalate supports. In contrast, particles grown on Na-TSM and α-Zr(HPO4)2·H2O nanosheets were larger and had a broad size distribution. ETEM, X-ray absorption spectroscopy, and pair distribution function analyses were used to study the growth of supported nanoparticles under oxidizing and reducing conditions, as well as the transformation from Rh(OH)3 to Rh nanoparticles. Interfacial covalent bonding, possibly strengthened by d-electron acid/base interactions, appear to stabilize Rh(OH)3, Rh2O3, and Rh nanoparticles on niobate and tantalate supports.

  4. Low Temperature Processed Complementary Metal Oxide Semiconductor (CMOS) Device by Oxidation Effect from Capping Layer

    KAUST Repository

    Wang, Zhenwei

    2015-04-20

    In this report, both p- and n-type tin oxide thin-film transistors (TFTs) were simultaneously achieved using single-step deposition of the tin oxide channel layer. The tuning of charge carrier polarity in the tin oxide channel is achieved by selectively depositing a copper oxide capping layer on top of tin oxide, which serves as an oxygen source, providing additional oxygen to form an n-type tin dioxide phase. The oxidation process can be realized by annealing at temperature as low as 190°C in air, which is significantly lower than the temperature generally required to form tin dioxide. Based on this approach, CMOS inverters based entirely on tin oxide TFTs were fabricated. Our method provides a solution to lower the process temperature for tin dioxide phase, which facilitates the application of this transparent oxide semiconductor in emerging electronic devices field.

  5. Optical properties of graphene oxide and reduced graphene oxide determined by spectroscopic ellipsometry

    Science.gov (United States)

    Schöche, Stefan; Hong, Nina; Khorasaninejad, Mohammadreza; Ambrosio, Antonio; Orabona, Emanuele; Maddalena, Pasqualino; Capasso, Federico

    2017-11-01

    We report the optical constants of graphene oxide and reduced graphene oxide determined by spectroscopic ellipsometry. The dynamic changes in optical properties and thickness of a drop-cast graphene oxide layer during reduction by long-term exposure to focused broad-band white light are monitored in situ. The anisotropic optical constants of the graphene oxide layer and the isotropically averaged optical constants of the reduced layer are precisely determined from a multiple-location analysis of spatially resolved data across the exposed location and a multiple-time-step analysis of the dynamic data, respectively. Observed inter-band transitions in the graphene oxide layer are discussed in relation to theoretical predictions for different coverage levels of the graphene oxide sheets with oxygen containing functional groups. The derived optical constants of the reduced graphene oxide layer are compared to reported values of graphene and thermally reduced graphene oxide.

  6. Chromite oxidation by manganese oxides in subseafloor basalts and the presence of putative fossilized microorganisms

    National Research Council Canada - National Science Library

    Ivarsson, Magnus; Broman, Curt; Holm, Nils G

    2011-01-01

    Chromite is a mineral with low solubility and is thus resistant to dissolution. The exception is when manganese oxides are available, since they are the only known naturally occurring oxidants for chromite...

  7. A nine-atom rhodium-aluminum oxide cluster oxidizes five carbon monoxide molecules

    National Research Council Canada - National Science Library

    Li, Xiao-Na; Zhang, Hua-Min; Yuan, Zhen; He, Sheng-Gui

    2016-01-01

    ... catalysis is elusive. Here we report that a single atom of rhodium, a powerful noble metal catalyst, can promote the transfer of five oxygen atoms to oxidize carbon monoxide from a nine-atom rhodium-aluminum oxide cluster...

  8. Triflic acid catalyzed oxidative lactonization and diacetoxylation of alkenes using peroxyacids as oxidants.

    Science.gov (United States)

    Kang, Yan-Biao; Gade, Lutz H

    2012-02-03

    A clean and efficient diacetoxylation reaction of alkenes catalyzed by triflic acid using commercially available peroxyacids as the oxidants has been developed. This method was also applied in oxidative lactonizations of unsaturated carboxylic acids in good to high yields.

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

    DEFF Research Database (Denmark)

    Christiansen, Liselotte Bruun; Dela, Flemming; Koch, Jørgen

    2015-01-01

    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...

  10. Oxidation behavior of metallic interconnect in solid oxide fuel cell stack

    Science.gov (United States)

    Li, Jun; Zhang, Wenying; Yang, Jiajun; Yan, Dong; Pu, Jian; Chi, Bo; Jian, Li

    2017-06-01

    Oxidation behavior of integrated interconnect with bipolar plate and corrugated sheet made by ferrite steel SUS430 is investigated and compared in simulated environment and in a realistic stack. Electrical current is found to have a direction-related impact on the thickness of the Cr2O3/MnCr2O4 composite oxide scale. Oxide scale of the interconnect aged in the stack exhibits a dual-layered structure of a complex Mn-Cr oxide layer covered by iron oxide. The oxidation rates vary greatly depending on its local environment, with different thermal, electrical density, as well as gas composition conditions. By analyzing the thickness distribution of oxide scale and comparing them with the simulated test result, the oxidation behavior of interconnect in stack is described in high definition. ASR distribution is also conducted by calculation, which could help further understanding the behavior of stack degradation.

  11. Indium Tin Oxide Resistor-Based Nitric Oxide Microsensors

    Science.gov (United States)

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

    2012-01-01

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

  12. Comparison of Nitrogen Oxide Metabolism among Diverse Ammonia-Oxidizing Bacteria

    OpenAIRE

    Jessica Ann Kozlowski; K Dimitri Kits; Stein, Lisa Y.

    2016-01-01

    Ammonia-oxidizing bacteria (AOB) have well characterized genes that encode and express nitrite reductases (NIR) and nitric oxide reductases (NOR). However, the connection between presence or absence of these and other genes for nitrogen transformations with the physiological production of nitric oxide (NO) and nitrous oxide (N2O) has not been tested across AOB isolated from various trophic states, with diverse phylogeny, and with closed genomes. It is therefore unclear if genomic content for ...

  13. Immunobiology of Nitric Oxide and Regulation of Inducible Nitric Oxide Synthase.

    Science.gov (United States)

    Lee, Martin; Rey, Kevin; Besler, Katrina; Wang, Christine; Choy, Jonathan

    Nitric oxide (NO) is a bioactive gas that has multiple roles in innate and adaptive immune responses. In macrophages, nitric oxide is produced by inducible nitric oxide synthase upon microbial and cytokine stimulation. It is needed for host defense against pathogens and for immune regulation. This review will summarize the role of NO and iNOS in inflammatory and immune responses and will discuss the regulatory mechanisms that control inducible nitric oxide synthase expression and activity.

  14. Graphite oxide: a selective and highly efficient oxidant of thiols and sulfides.

    Science.gov (United States)

    Dreyer, Daniel R; Jia, Hong-Peng; Todd, Alexander D; Geng, Jianxin; Bielawski, Christopher W

    2011-11-07

    The selective oxidation of thiols to disulfides and sulfides to sulfoxides using graphite oxide (GO), a heterogeneous carbocatalyst obtained from low cost, commercial starting materials is described. The aforementioned oxidation reactions were found to proceed rapidly (as short as 10 min in some cases) and in good yield (51-100%) (19 examples). No over-oxidation of the substrates was observed, and GO's heterogeneous nature facilitated isolation and purification of the target products.

  15. Thin cuprous oxide films prepared by thermal oxidation of copper foils with water vapor

    Energy Technology Data Exchange (ETDEWEB)

    Liang Jianbo, E-mail: liangjienbo1980@yahoo.co.jp [Department of Frontier Materials,Nagoya Institute of Technology, Nagoya 4668555 (Japan); Kishi, Naoki; Soga, Tetsuo [Department of Frontier Materials,Nagoya Institute of Technology, Nagoya 4668555 (Japan); Jimbo, Takashi [Research Center for Nano-Device and System, Nagoya Institute of Technology, Nagoya 4668555 (Japan); Ahmed, Mohsin [Department of Frontier Materials,Nagoya Institute of Technology, Nagoya 4668555 (Japan)

    2012-01-31

    We present an improved preparation method for the growth of high quality crystals of cuprous oxide films grown by thermal oxidation of cupper foils with water vapor. This method proved to be good for preparing cuprous oxide films with high purity and large grain size. X-ray diffraction studies revealed the formation of Cu{sub 2}O films with preferred (111) orientation. The cuprous oxide diodes fabricated by the above technique have been studied using current-voltage method.

  16. Platinum nanoparticles–manganese oxide nanorods as novel binary catalysts for formic acid oxidation

    OpenAIRE

    El-Deab, Mohamed S.

    2012-01-01

    The current study proposes a novel binary catalyst system (composed of metal/metal oxide nanoparticles) as a promising electrocatalyst in formic acid oxidation. The electro-catalytic oxidation of formic acid is carried out with binary catalysts of Pt nanoparticles (nano-Pt) and manganese oxide nanorods (nano-MnOx) electrodeposited onto glassy carbon (GC) electrodes. Cyclic voltammetric (CV) measurements showed that unmodified GC and nano-MnOx/GC electrodes have no catalytic activity. While tw...

  17. The oxidative coupling of methane and the oxidative dehydrogenation of ethane over a niobium promoted lithium doped magnesium oxide catalyst

    NARCIS (Netherlands)

    Swaan, H.M.; Swaan, H.M.; Li, X.; Seshan, Kulathuiyer; van Ommen, J.G.; Ross, J.R.H.; Ross, J.R.H.

    1993-01-01

    The promoting effect of niobium in a Li/MgO catalyst for the oxidative coupling of methane (OCM) and for the oxidative dehydrogenation of ethane (ODHE) has been studied in some detail. It has been found that a Li/Nb/MgO catalyst with 16 wt % niobium showed the highest activity for the C2 production

  18. Oxidative stress response in sugarcane

    Directory of Open Access Journals (Sweden)

    Luis Eduardo Soares Netto

    2001-12-01

    Full Text Available Oxidative stress response in plants is still poorly understood in comparison with the correspondent phenomenon in bacteria, yeast and mammals. For instance, nitric oxide is assumed to play various roles in plants although no nitric oxide synthase gene has yet been isolated. This research reports the results of a search of the sugarcane expressed sequence tag (SUCEST database for homologous sequences involved in the oxidative stress response. I have not found any gene similar to nitric oxide synthase in the SUCEST database although an alternative pathway for nitric oxide synthesis was proposed. I have also found several genes involved in antioxidant defense, e.g. metal chelators, low molecular weight compounds, antioxidant enzymes and repair systems. Ascorbate (vitamin C is a key antioxidant in plants because it reaches high concentrations in cells and is a substrate for ascorbate peroxidase, an enzyme that I found in different isoforms in the SUCEST database. I also found many enzymes involved in the biosynthesis of low molecular weight antioxidants, which may be potential targets for genetic manipulation. The engineering of plants for increased vitamin C and E production may lead to improvements in the nutritional value and stress tolerance of sugarcane. The components of the antioxidant defense system interact and their synthesis is probably closely regulated. Transcription factors involved in regulation of the oxidative stress response in bacteria, yeast and mammals differ considerably among themselves and when I used them to search the SUCEST database only genes with weak similarities were found, suggesting that these transcription regulators are not very conserved. The involvement of reactive oxygen species and antioxidants in plant defense against pathogens is also discussed.A resposta ao estresse oxidativo não é bem conhecida em plantas como em bactérias, leveduras e humanos. Por exemplo, assume-se que óxido nítrico tem várias fun

  19. Development of the inner oxide zone upon steam oxidation of an austenitic stainless steel

    DEFF Research Database (Denmark)

    Hansson, Anette N.; Montgomery, Melanie; Somers, Marcel A. J.

    2009-01-01

    The oxidation behaviour of TP 347H FG in mixtures of water, oxygen, and hydrogen was investigated in the temperature range 500 – 700C for a fixed oxidation time of 336 h. The samples were characterised using reflective light and electron microscopy methods. Thin discontinuous double-layered oxide...

  20. Field test results for steam oxidation of TP347H FG - growth of inner oxide

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Jianmin, Jia; Larsen, OH

    2005-01-01

    and the thickness of the inner oxide has been investigated by light optical and scanning electron microscopy equipped with EDS. Comparison of inner oxide pit thickness revealed that an increase in temperature from 455 to 525C increased the oxidation rate. A further increase in temperature did not result in thicker...

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

    Science.gov (United States)

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

  2. Triacylglycerols composition, oxidation and oxidation compounds in camellia oil using liquid chromatography-mass spectrometry.

    Science.gov (United States)

    Zeb, Alam

    2012-07-01

    Camellia seed oil is one of most important edible oil, rich in oleic acid and contains many natural antioxidants with various biological activities. During preparation of foods or storage camellia oil oxidizes by the auto-oxidation and produce oxidized compounds. Traditional analytical techniques like FFA, POV are used for the determination of oxidation and adulteration of oils and fats. These methods were rarely able to detect the oxidized compounds produced and extent of oxidation. This paper presents the uses of liquid chromatography coupled to electrospray ionization mass spectrometry (HPLC-ESI-MS) for the analysis of triacylglycerols (TAGs) composition and evaluation of auto-oxidation and oxidation products of camellia seed oil. The camellia oil was auto-oxidized for 12 months at room temperature. The TAGs were identified from their characteristics fragmentations such as protonated molecular ion, ammonium and sodium adducts, diacylglycerols, epoxy-diacylglycerols fragments and mono-acylglycerol fragments in ESI-MS mass spectra. HPLC-ESI-MS data revealed the separation and identification of 15 TAGs. The major TAGs separated and identified in camellia seed oil were POO, OOO, OLO, PLO/POL, OLL, SOO, ALO and OLLn. The auto-oxidation studies revealed a total loss of LnLLn, LnOLn, LLLn and OLLn amounting about 13.5% total oxidation. The auto-oxidation products were epoxy hydroperoxides, epoxy epidioxides, and mono-epoxides. It was observed that these were characteristic compounds produced in high oleic oils. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  3. Anaerobic sulfide-oxidation in marine colorless sulfur-oxidizing bacteria

    Digital Repository Service at National Institute of Oceanography (India)

    LokaBharathi, P.A.; Nair, S.; Chandramohan, D.

    . Subsequently, the percentage oxidation was higher at 45 ppm but decreased at 64 ppm. Iron had a variable effect on sulfide oxidation. The viability of the cells and efficiency of oxidation increased in the presence of nitrate. An increase in temperature beyond...

  4. Interaction mechanisms between slurry coatings and solid oxide fuel cell interconnect alloys during high temperature oxidation

    DEFF Research Database (Denmark)

    Persson, Åsa Helen; Mikkelsen, L.; Hendriksen, P.V.

    2012-01-01

    oxidation rate constant was reduced with 50–90% of that for uncoated alloy. One coating consisting of MnCo2O4 did not significantly affect the oxidation rate of the alloy, and just as for uncoated samples break-away oxidation occurred for MnCo2O4 coated samples. The interaction mechanisms between...

  5. Fundamentals of Mercury Oxidation in Flue Gas

    Energy Technology Data Exchange (ETDEWEB)

    JoAnn Lighty; Geoffrey Silcox; Constance Senior; Joseph Helble; Balaji Krishnakumar

    2008-07-31

    The objective of this project was to understand the importance of and the contribution of gas-phase and solid-phase coal constituents in the mercury oxidation reactions. The project involved both experimental and modeling efforts. The team was comprised of the University of Utah, Reaction Engineering International, and the University of Connecticut. The objective was to determine the experimental parameters of importance in the homogeneous and heterogeneous oxidation reactions; validate models; and, improve existing models. Parameters studied include HCl, NO{sub x}, and SO{sub 2} concentrations, ash constituents, and temperature. The results suggested that homogeneous mercury oxidation is below 10% which is not consistent with previous data of others and work which was completed early in this research program. Previous data showed oxidation above 10% and up to 100%. However, the previous data are suspect due to apparent oxidation occurring within the sampling system where hypochlorite ion forms in the KCl impinger, which in turn oxidized mercury. Initial tests with entrained iron oxide particles injected into a flame reactor suggest that iron present on fly ash particle surfaces can promote heterogeneous oxidation of mercury in the presence of HCl under entrained flow conditions. Using the data generated above, with homogeneous reactions accounting for less than 10% of the oxidation, comparisons were made to pilot- and full-scale data. The results suggest that heterogeneous reactions, as with the case of iron oxide, and adsorption on solid carbon must be taking place in the full-scale system. Modeling of mercury oxidation using parameters from the literature was conducted to further study the contribution of homogeneous pathways to Hg oxidation in coal combustion systems. Calculations from the literature used rate parameters developed in different studies, in some cases using transition state theory with a range of approaches and basis sets, and in other cases

  6. Photoluminescence investigation about zinc oxide with graphene oxide & reduced graphene oxide buffer layers.

    Science.gov (United States)

    Ding, Jijun; Wang, Minqiang; Zhang, Xiangyu; Yang, Zhi; Song, Xiaohui; Ran, Chenxin

    2014-02-15

    ZnO with graphene oxide (GO-ZnO) & reduced graphene oxide (rGO-ZnO) buffer layers were fabricated. Photoluminescence (PL) properties of GO-ZnO and rGO-ZnO compositions induced by oxygen vacancies defects were investigated using photoluminescence spectroscopy. The results showed that blue emission is quenched while yellow-orange emissions from GO-ZnO and rGO-ZnO compositions are significantly increased as compared to that of ZnO films. In stark contrast to enhanced yellow-orange emissions, PL spectra show three sharp, discrete emissions that characterize the dominant optical active defect, which is the oxygen vacancies and extended oxygen vacancies. Our results highlight the ability of GO & rGO buffer layers to modulate defect concentrations in ZnO and contribute to understanding the optical properties of deep-level defects, which is significant for development of long-wavelength photoelectric devices related with graphene materials. Crown Copyright © 2013. Published by Elsevier Inc. All rights reserved.

  7. Thioredoxin, oxidative stress, cancer and aging.

    Science.gov (United States)

    Flores, Lisa C; Ortiz, Melanie; Dube, Sara; Hubbard, Gene B; Lee, Shuko; Salmon, Adam; Zhang, Yiqiang; Ikeno, Yuji

    2012-01-01

    The Free Radical or Oxidative Stress Theory of Aging is one of the most popular theories in aging research and has been extensively studied over the past several decades. However, recent evidence using transgenic/knockout mice that overexpress or down-regulate antioxidant enzymes challenge the veracity of this theory since the animals show no increase or decrease in lifespan. These results seriously call into question the role of oxidative damage/stress in the aging process in mammals. Therefore, the theory requires significant modifications if we are to understand the relationship between aging and the regulation of oxidative stress. Our laboratory has been examining the impacts of thioredoxins (Trxs), in the cytosol and mitochondria, on aging and age-related diseases. Our data from mice that are either up-regulating or down-regulating Trx in different cellular compartments, that is, the cytosol or mitochondria, could shed some light on the role of oxidative stress and its pathophysiological effects. The results generated from our lab and others may indicate that: 1) changes in oxidative stress and the redox state in the cytosol, mitochondria or nucleus might play different roles in the aging process; 2) the role of oxidative stress and redox state could have different pathophysiological consequences in different tissues/cells, for example, mitotic vs. post-mitotic; 3) oxidative stress could have different pathophysiological impacts in young and old animals; and 4) the pathophysiological roles of oxidative stress and redox state could be controlled through changes in redox-sensitive signaling, which could have more diverse effects on pathophysiology than the accumulation of oxidative damage to various molecules. To critically test the role of oxidative stress on aging and age-related diseases, further study is required using animal models that regulate oxidative stress levels differently in each cellular compartment, each tissue/organ, and/or at different stages

  8. Determining cysteine oxidation status using differential alkylation

    Science.gov (United States)

    Schilling, Birgit; Yoo, Chris B.; Collins, Christopher J.; Gibson, Bradford W.

    2004-08-01

    Oxidative damage to proteins plays a major role in aging and in the pathology of many degenerative diseases. Under conditions of oxidative stress, reactive oxygen and nitrogen species can modify key redox sensitive amino acid side chains leading to altered biological activities or structures of the targeted proteins. This in turn can affect signaling or regulatory control pathways as well as protein turnover and degradation efficiency in the proteasome. Cysteine residues are particularly susceptible to oxidation, primarily through reversible modifications (e.g., thiolation and nitrosylation), although irreversible oxidation can lead to products that cannot be repaired in vivo such as sulfonic acid. This report describes a strategy to determine the overall level of reversible cysteine oxidation using a stable isotope differential alkylation approach in combination with mass spectrometric analysis. This method employs 13C-labeled alkylating reagents, such as N-ethyl-[1,4-13C2]-maleimide, bromo-[1,2-13C2]-acetic acid and their non-labeled counterparts to quantitatively assess the level of cysteine oxidation at specific sites in oxidized proteins. The differential alkylation protocol was evaluated using standard peptides and proteins, and then applied to monitor and determine the level of oxidative damage induced by diamide, a mild oxidant. The formation and mass spectrometric analysis of irreversible cysteine acid modification will also be discussed as several such modifications have been identified in subunits of the mitochondrial electron transport chain complexes. This strategy will hopefully contribute to our understanding of the role that cysteine oxidation plays in such chronic diseases such as Parkinson's disease, where studies in animal and cell models have shown oxidative damage to mitochondrial Complex I to be a specific and early target.

  9. Ambient temperature NO oxidation over Cr-based amorphous mixed oxide catalysts: effects from the second oxide components

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Aiyong; Lin, Bo; Zhang, Hanlei; Engelhard, Mark H.; Guo, Yanglong; Lu, Guanzhong; Peden, Charles HF; Gao, Feng

    2017-01-01

    Three series of Cr-based mixed oxides (Cr-Co, Cr-Fe, and Cr-Ni oxides) with high specific surface areas and amorphous textures were synthesized using a novel sol-gel method. These mixed oxides, in comparison to their pure metal oxide (CrOx, Co3O4, FeOx and NiO) counterparts, display enhanced performance for catalytic oxidation of low-concentration NO at room temperature. The best performing catalysts achieve 100% NO conversion for ~30 h of operation at a high space velocity of 45,000 ml g-1 h-1. The amorphous structure was found to be critical for these catalysts to maintain high activity and durability. Control of Cr/M (M=Co, Fe and Ni) molar ratio, nitrate precursor decomposition temperature and catalyst calcination temperature was key to the synthesis of these highly active catalysts.

  10. Polyethylene oxide-fullerene nanocomposites

    Science.gov (United States)

    Ali, Nasar; Chipara, Dorina; Lozano, Karen; Hinthorne, James; Chipara, Mircea

    2017-11-01

    Polyethylene oxide - fullerene nanocomposites have been prepared by using the solution path with water as solvent (only for the polymer). The dispersion of C60 within the polymer solution was achieved by high power sonication. The study aims to a better understanding on the effect of C60 nanoparticles on the macromolecular chains. Raman Wide Angle X Ray spectroscopy, Differential Scanning Calorimetry, and Thermogravimetric Analysis were used to inspect the interactions between the nanofiller and macromolecular chains. The experimental results revealed a completely different behavior of fullerene dispersed within polymeric matrices than using carbon nanotubes or nanofibers as nanofiller. The observed behavior was explained by the low aspect ratio of C60 compared to nanotubes and by the low thermal conductivity of C60 compared to the thermal conductivity of others carbon nanostructures.

  11. Evaporative oxidation treatability test report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-04-01

    In 1992, Congress passed the Federal Facilities Compliance Act that requires the U.S. Department of Energy (DOE) to treat and dispose of its mixed waste in accordance with the Resource Conservation and Recovery Act (RCRA) land disposal restrictions (LDRs). In response to the need for mixed-waste treatment capacity where available off-site commercial treatment facilities do not exist or cannot be used, the DOE Albuquerque Operations Office (DOE-AL) organized a Treatment Selection Team to match mixed wastes with treatment options and develop a strategy for treatment of its mixed wastes. DOE-AL manages operations at nine sites with mixed-waste inventories. The Treatment Selection Team determined a need to develop mobile treatment capacity to treat wastes at the sites where the wastes are generated. Treatment processes used for mixed waste not only must address the hazardous component (i.e., meet LDRs) but also must contain the radioactive component in a form that allows final disposal while protecting workers, the public, and the environment. On the basis of recommendations of the Treatment Selection Team, DOE-AL assigned projects to the sites to bring mixed-waste treatment capacity on-line. The three technologies assigned to the DOE Grand Junction Projects Office (GJPO) are evaporative oxidation, thermal desorption, and treated wastewater evaporation. Rust Geotech, the DOE-GJPO prime contractor, was assigned to design and fabricate mobile treatment units (MTUs) for these three technologies and to deliver the MTUs to selected DOE-AL sites. To conduct treatability tests at the GJPO, Rust leased a pilot-scale evaporative oxidation unit from the Clemson Technical Center (CTC), Anderson, South Carolina. The purpose of this report is to document the findings and results of tests performed using this equipment.

  12. Nitric oxide signaling in hypoxia.

    Science.gov (United States)

    Ho, J J David; Man, H S Jeffrey; Marsden, Philip A

    2012-03-01

    Endothelial-derived nitric oxide (NO) is classically viewed as a regulator of vasomotor tone. NO plays an important role in regulating O(2) delivery through paracrine control of vasomotor tone locally and cardiovascular and respiratory responses centrally. Very soon after the cloning and functional characterization of the endothelial nitric oxide synthase (eNOS), studies on the interaction between O(2) and NO made the paradoxical finding that hypoxia led to decreases in eNOS expression and function. Why would decreases in O(2) content in tissues elicit a loss of a potent endothelial-derived vasodilator? We now know that restricting our view of NO as a regulator of vasomotor tone or blood pressure limited deeper levels of mechanistic insight. Exciting new studies indicate that functional interactions between NO and O(2) exhibit profound complexity and are relevant to diseases states, especially those associated with hypoxia in tissues. NOS isoforms catalytically require O(2). Hypoxia regulates steady-state expression of the mRNA and protein abundance of the NOS enzymes. Animals genetically deficient in NOS isoforms have perturbations in their ability to adapt to changes in O(2) supply or demand. Most interestingly, the intracellular pathways for O(2) sensing that evolved to ensure an appropriate balance of O(2) delivery and utilization intersect with NO signaling networks. Recent studies demonstrate that hypoxia-inducible factor (HIF) stabilization and transcriptional activity is achieved through two parallel pathways: (1) a decrease in O(2)-dependent prolyl hydroxylation of HIF and (2) S-nitrosylation of HIF pathway components. Recent findings support a role for S-nitrosothiols as hypoxia-mimetics in certain biological and/or disease settings, such as living at high altitude, exposure to small molecules that can bind NO, or anemia.

  13. Nitric oxide and chronic colitis

    Directory of Open Access Journals (Sweden)

    Matthew B Grisham

    1996-01-01

    Full Text Available Nitric oxide (NO is thought to play an important role in modulating the inflammatory response by virtue of its ability to affect bloodflow, leukocyte function and cell viability. The objective of this study was to assess the role that NO may play in mediating the mucosal injury and inflammation in a model of chronic granulomatous colitis using two pharmacologically different inhibitors of nitric oxide synthase (NOS. Chronic granulomatous colitis with liver and spleen inflammation was induced in female Lewis rats via the subserosal (intramural injection of peptidoglycan/polysaccharide (PG/PS derived from group A streptococci. Chronic NOS inhibition by oral administration of NG-nitro-L-arginine methyl ester (L-NAME (15 µmol/kg/day or amino-guanidine (AG (15 µmol/ kg/day was found to attenuate the PG/PS-induced increases in macroscopic colonic inflammation scores and colonic myeloperoxidase activity. Only AG -- not L-NAME – attenuated the PG/PS-induced increases in colon dry weight. Both L-NAME and AG significantly attenuated the PG/PS-induced increases in spleen weight whereas neither was effective at significantly attenuating the PG/PS-induced increases in liver weight. Although both L-NAME and AG inhibited NO production in vivo, as measured by decreases in plasma nitrite and nitrate levels, only AG produced significantly lower values (38±3 versus 83±8 µM, respectively, P<0.05. Finally, L-NAME, but not AG, administration significantly increased mean arterial pressure from 83 mmHg in colitic animals to 105 mmHg in the PG/PS+ L-NAME-treated animals (P<0.05. It is concluded that NO may play an important role in mediating some of the pathophysiology associated with this model of chronic granulomatous colitis.

  14. Anticholinesterase Toxicity and Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Dejan Milatovic

    2006-01-01

    Full Text Available Anticholinesterase compounds, organophosphates (OPs and carbamates (CMs are commonly used for a variety of purposes in agriculture and in human and veterinary medicine. They exert their toxicity in mammalian system primarily by virtue of acetylcholinesterase (AChE inhibition at the synapses and neuromuscular junctions, leading into the signs of hypercholinergic preponderance. However, the mechanism(s involved in brain/muscle damage appear to be linked with alteration in antioxidant and the scavenging system leading to free radical-mediated injury. OPs and CMs cause excessive formation of F2-isoprostanes and F4-neuroprostanes, in vivo biomarkers of lipid peroxidation and generation of reactive oxygen species (ROS, and of citrulline, a marker of NO/NOS and reactive nitrogen species (RNS generation. In addition, during the course of these excitatory processes and inhibition of AChE, a high rate of ATP consumption, coupled with the inhibition of oxidative phosphorylation, compromise the cell's ability to maintain its energy levels and excessive amounts of ROS and RNS may be generated. Pretreatment with N-methyl D-aspartate (NMDA receptor antagonist memantine, in combination with atropine sulfate, provides significant protection against inhibition of AChE, increases of ROS/RNS, and depletion of high-energy phosphates induced by DFP/carbofuran. Similar antioxidative effects are observed with a spin trapping agent, phenyl-N-tert-butylnitrone (PBN or chain breaking antioxidant vitamin E. This review describes the mechanisms involved in anticholinesterase-induced oxidative/nitrosative injury in target organs of OPs/CMs, and protection by various agents.

  15. Tabulated Neutron Emission Rates for Plutonium Oxide

    Energy Technology Data Exchange (ETDEWEB)

    Shores, Erik Frederick [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-07-24

    This work tabulates neutron emission rates for 80 plutonium oxide samples as reported in the literature. Plutonium-­238 and plutonium-­239 oxides are included and such emission rates are useful for scaling tallies from Monte Carlo simulations and estimating dose rates for health physics applications.

  16. ORIGINAL ARTICLE Relationship between endothelial nitric oxide ...

    African Journals Online (AJOL)

    salah

    Introduction: Endothelial nitric oxide synthase (eNOS), the enzyme in charge of nitric oxide production, plays a crucial role in vascular biology. However, the impact of single nucleotide polymorphisms (SNPs) affecting the gene encoding for eNOS (eNOS) on coronary artery diseases remains under debate and no data were ...

  17. Ammonia release method for depositing metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Silver, G.L.; Martin, F.S.

    1993-12-31

    A method of depositing metal oxides on substrates which is indifferent to the electrochemical properties of the substrates and which comprises forming ammine complexes containing metal ions and thereafter effecting removal of ammonia from the ammine complexes so as to permit slow precipitation and deposition of metal oxide on the substrates.

  18. Oxidative stress in primary glomerular diseases

    DEFF Research Database (Denmark)

    Markan, Suchita; Kohli, Harbir Singh; Sud, Kamal

    2008-01-01

    To evaluate the status of oxidative stress in patients with different primary glomerular diseases (PGD) which have differential predisposition to renal failure.......To evaluate the status of oxidative stress in patients with different primary glomerular diseases (PGD) which have differential predisposition to renal failure....

  19. Solvothermal synthesis of cobalt oxides nanocrystals

    Science.gov (United States)

    Shao, Wenyao; Yan, Mengwen

    2017-05-01

    CoO and Co3O4 nanocrystals (NCs) were synthesized by a one-pot solvothermal reaction in the presence of the oxidant NaOH and the surfactant cetyltrimethyl ammonium bromide (CTAB). The as-prepared cobalt oxide nanoparticles are size uniformed and have good dispersibility and good crystallinity.

  20. Nanocomposite of graphene and metal oxide materials

    Science.gov (United States)

    Liu, Jun; Aksay, Ilhan A.; Choi, Daiwon; Wang, Donghai; Yang, Zhenguo

    2013-10-15

    Nanocomposite materials comprising a metal oxide bonded to at least one graphene material. The nanocomposite materials exhibit a specific capacity of at least twice that of the metal oxide material without the graphene at a charge/discharge rate greater than about 10 C.

  1. Pulsed laser deposition: metal versus oxide ablation

    NARCIS (Netherlands)

    Doeswijk, L.M.; Rijnders, Augustinus J.H.M.; Blank, David H.A.

    2004-01-01

    We present experimental results of pulsed laser interaction with metal (Ni, Fe, Nb) and oxide (TiO2, SrTiO3, BaTiO3) targets. The influence of the laser fluence and the number of laser pulses on the resulting target morphology are discussed. Although different responses for metal and oxide targets

  2. 29 CFR 1910.1047 - Ethylene oxide.

    Science.gov (United States)

    2010-07-01

    ..., away from heat, sparks, flames, strong oxidizers, alkalines, and acids, strong bases, acetylide-forming... containers of EtO leave the workplace. For the purpose of this paragraph, reaction vessels, storage tanks..., mineral acids, metal chlorides, or metal oxides. Violent decomposition will also occur at temperatures...

  3. Inducible nitric oxide synthase in renal transplantation

    NARCIS (Netherlands)

    Joles, JA; Vos, IH; Grone, HJ; Rabelink, TJ

    The importance of the endothelial isoform of nitric oxide synthase (eNOS) has been well established. Endothelium-derived nitric oxide has been shown to be essential for vascular homeostasis and modulation of eNOS has thus become a target in prevention of cardiovascular disease. The role of the

  4. Relationship between endothelial nitric oxide synthase gene ...

    African Journals Online (AJOL)

    Introduction: Endothelial nitric oxide synthase (eNOS), the enzyme in charge of nitric oxide production, plays a crucial role in vascular biology. However, the impact of single nucleotide polymorphisms (SNPs) affecting the gene encoding for eNOS (eNOS) on coronary artery diseases remains under debate and no data were ...

  5. Self-Terminating, Oxidative Radical Cyclizations

    Directory of Open Access Journals (Sweden)

    Uta Wille

    2004-05-01

    Full Text Available The recently discovered novel concept of self-terminating, oxidative radical cyclizations, through which alkynes can be converted into carbonyl compounds under very mild reaction conditions using O-centered inorganic and organic radicals as oxidants, is described

  6. Tannin biosynthesis of iron oxide nanoparticles

    Science.gov (United States)

    Herrera-Becerra, R.; Rius, J. L.; Zorrilla, C.

    2010-08-01

    In this work, iron oxide nanoparticles synthesized with gallic acid and tannic acid are characterized using High-Resolution Transmission Electron Microscopy (HRTEM). Its size, form, and structure are compared with nanoparticles obtained previously using alfalfa biomass in order to find a simpler, consistent, and environmentally friendly method in the production of iron oxide nanoparticles.

  7. Oxidative stress and histopathological changes induced by ...

    African Journals Online (AJOL)

    was marked by the enhanced TBARS (thiobarbituric acid reactive substances) production in the liver and kidney of. MT treated rats indicating MT pro-oxidant effects to alter membrane integrity and fluidity. Many xenobiotics, such as pesticides, are known to induce oxidative damage through ROS generation and can alter.

  8. 29 CFR 1915.1047 - Ethylene oxide.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Ethylene oxide. 1915.1047 Section 1915.1047 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR... § 1915.1047 Ethylene oxide. Note: The requirements applicable to shipyard employment under this section...

  9. 29 CFR 1926.1147 - Ethylene oxide.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Ethylene oxide. 1926.1147 Section 1926.1147 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR... Ethylene oxide. Note: The requirements applicable to construction work under this section are identical to...

  10. Electrochemical oxidation of substituted benzylamines in aquo ...

    Indian Academy of Sciences (India)

    Electrochemical oxidation of nine para- and meta-substituted benzylamines in varying mole fractions of acetic acid in water has been investigated in the presence of 0.1 M sulphuric acid as supporting electrolyte. The oxidation potentials correlate well with Hammett's substituent constants affording negative reaction ...

  11. Tire containing thermally exfoliated graphite oxide

    Science.gov (United States)

    Prud'homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor)

    2011-01-01

    A tire, tire lining or inner tube, containing a polymer composite, made of at least one rubber and/or at least one elastomer and a modified graphite oxide material, which is a thermally exfoliated graphite oxide with a surface area of from about 300 sq m/g to 2600 sq m/g.

  12. Photochemical Transformation of Graphene Oxide in Sunlight

    Science.gov (United States)

    Graphene oxide (GO) is a graphene derivative that is more easily manufactured in large scale and used to synthesize reduced graphene oxide (rGO) with properties analogous to graphene. In this study, we investigate the photochemical fate of GO under sunlight conditions. The resu...

  13. An Overview of β-Oxidation Disorders

    Directory of Open Access Journals (Sweden)

    Dariusz Moczulski

    2009-06-01

    Full Text Available Fatty acids (FAs are components of cell membrane, enzymes, and hormones and are one of the most important energy sources for many organisms. There are several types of fatty-acid oxidative degradation processes in the cell, namely alpha-, beta-, and omega-oxidation, which take place in specialized cellular structures: mitochondria and peroxisomes. The best-known pathway is β-oxidation taking place in the matrix of mitochondria. It is responsible for the degradation of straight-chain FAs. The pathway of β-oxidation of fatty acids is comprised of at least 25 enzymes and specific transport proteins. Deficiencies in 18 of them have been demonstrated to cause disease in humans. These diseases show a wide variety of symptoms, which can be expressed at random, one at a time, or in sets, characteristic of the individual rather than the metabolic character of the disease. Disorders of β-oxidation are believed to cause about 1–3�0of unexplained sudden infant deaths (SIDS. Acute fatty liver of pregnancy (AFLP and the syndrome of hemolysis, elevated liver enzymes, and low platelets (HELLP syndrome, which have significant neonatal and maternal morbidity and mortality, have also been associated with β-oxidation deficiency in fetuses. This review summarizes recent observations on disorders associated with fatty-acid oxidation: deficiencies of β-oxidation enzymes, namely VLCAD, TFP and LCHAD, MCAD, MCKAT, M/SCHAD, and SCAD, and deficiencies of the enzymes TCP I, CT, and CPT II of the carnitine cycle.

  14. Experimental study of oxidative DNA damage

    DEFF Research Database (Denmark)

    Loft, S; Deng, Xiaohong; Tuo, J

    1998-01-01

    of the use of 2-nitropropane as a model for oxidative DNA damage relate particularly to formation of 8-aminoguanine derivatives that may interfere with HPLC-EC assays and have unknown consequences. Other model compounds for induction of oxidative DNA damage, such as ferric nitriloacetate, iron dextran...

  15. Oxidative stress in diabetic patients with retinopathy

    African Journals Online (AJOL)

    as ulcers, neuropathy, and nephropathy which are known to affect oxidative stress parameters were excluded from the study. Any subject receiving antioxidant ... Oxidative stress in diabetic patients with retinopathy. After obtaining written consent, with 8 h of fasting,. 10 ml of venous blood was collected from the median.

  16. Anaerobic exercise and oxidative stress: a review.

    Science.gov (United States)

    Bloomer, Richard J; Goldfarb, Allen H

    2004-06-01

    Oxidative stress and subsequent damage to cellular proteins, lipids, and nucleic acids, as well as changes to the glutathione system, are well documented in response to aerobic exercise. However, far less information is available on anaerobic exercise-induced oxidative modifications. Recent evidence indicates that high intensity anaerobic work does result in oxidative modification to the above-mentioned macromolecules in both skeletal muscle and blood. Also, it appears that chronic anaerobic exercise training can induce adaptations that act to attenuate the exercise-induced oxidative stress. These may be specific to increased antioxidant defenses and/or may act to reduce the generation of pro-oxidants during and after exercise. However, a wide variety of exercise protocols and assay procedures have been used to study oxidative stress pertaining to anaerobic work. Therefore, precise conclusions about the exact extent and location of oxidative macromolecule damage, in addition to the adaptations resulting from chronic anaerobic exercise training, are difficult to indicate. This manuscript provides a review of anaerobic exercise and oxidative stress, presenting both the acute effects of a single exercise bout and the potential for adaptations resulting from chronic anaerobic training.

  17. Consecutive dynamic resolutions of phosphine oxides

    NARCIS (Netherlands)

    Kortmann, Felix A.; Chang, Mu Chieh; Otten, Edwin; Couzijn, Erik P A; Lutz, Martin; Minnaard, Adriaan J.

    2014-01-01

    A crystallization-induced asymmetric transformation (CIAT) involving a radical-mediated racemization provides access to enantiopure secondary phosphine oxides. A consecutive CIAT is used to prepare enantio- and diastereo-pure tert-butyl(hydroxyalkyl)phenylphosphine oxides. © 2014 The Royal Society

  18. Cervical nitric oxide release in women postterm.

    Science.gov (United States)

    Väisänen-Tommiska, Mervi; Nuutila, Mika; Ylikorkala, Olavi

    2004-04-01

    Nitric oxide may be a factor in cervical ripening. We compared the nitric oxide metabolite levels in cervical fluid in women going beyond term and in women delivering spontaneously at term. We studied a total of 208 women with singleton pregnancies: 108 women who went beyond term (294 days or longer), and 100 women who went spontaneously into labor at term. Cervical fluid samples, collected well before the initiation of labor, were assessed for nitric oxide metabolites using an assay with a detection limit of 3.8 micromol/L. Women going beyond term had detectable levels of nitric oxide metabolites in their cervical fluid (60%) less often (P =.001) than women delivering at term (87%). The nitric oxide metabolite concentration in cervical fluid in women going beyond term (median 23.5 micromol/L; 95% confidence interval less than 3.8, 31.8) was 4.5 times lower (P postterm labor were included in the comparison. Both nulliparous (median less than 3.8 micromol/L) and parous (median 31.3 micromol/L) women going beyond term had lower (P postterm group, women with cervical fluid nitric oxide metabolite concentrations at or below the median failed more often (P <.001) to progress in labor and had longer (P =.02) duration of labor than those with cervical fluid nitric oxide metabolite concentrations above the median. Reduced cervical nitric oxide release may contribute to prolonged pregnancy. II-2

  19. A STUDY OF OXIDATIVE STRESS IN DIABETES

    Directory of Open Access Journals (Sweden)

    Babu Rao

    2015-06-01

    Full Text Available Non - enzymatic free radical mediated oxidation of biological molecules, membranes and tissues is associated with a variety of pathological events such as cancer, aging and diabetes mellitus . [1] Increased oxidative stress is seen in both types of diabetes me llitus namely type 1 and type 2, irrespective of duration, complications and treatment. In diabetes mellitus, oxidative stress seems primarily due to both an increased plasma free radical concentration and a sharp decline in antioxidant defences . [1] Among the causes of enhanced free radical production, hyperglycemia and hyper insulinemia seem to play a major role , [2,3] Hyperglycemia is the more easily modifiable factor among the two and good glycemic control can reduce the oxidative stress. Controversy pers ists regarding the other possible mechanisms of increased oxidative stress in diabetes and whether oxidative stress normalizes with adequate metabolic control alone. The role of oxidative stress and diabetic complications has been extensively investigated. Oxidative stress has been suggested to be involved in the genesis of both macro and micro angiopathy [4,5] Prospective trials are now underway addressing the controversial issues of possible role of pharmacological antioxidants in preventing or at least de laying the onset of diabetic complications.

  20. Mesoporous Transition Metal Oxides for Supercapacitors

    Directory of Open Access Journals (Sweden)

    Yan Wang

    2015-10-01

    Full Text Available Recently, transition metal oxides, such as ruthenium oxide (RuO2, manganese dioxide (MnO2, nickel oxides (NiO and cobalt oxide (Co3O4, have been widely investigated as electrode materials for pseudo-capacitors. In particular, these metal oxides with mesoporous structures have become very hot nanomaterials in the field of supercapacitors owing to their large specific surface areas and suitable pore size distributions. The high specific capacities of these mesoporous metal oxides are resulted from the effective contacts between electrode materials and electrolytes as well as fast transportation of ions and electrons in the bulk of electrode and at the interface of electrode and electrolyte. During the past decade, many achievements on mesoporous transition metal oxides have been made. In this mini-review, we select several typical nanomaterials, such as RuO2, MnO2, NiO, Co3O4 and nickel cobaltite (NiCo2O4, and briefly summarize the recent research progress of these mesoporous transition metal oxides-based electrodes in the field of supercapacitors.

  1. Plutonium Oxide Process Capability Work Plan

    Energy Technology Data Exchange (ETDEWEB)

    Meier, David E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Tingey, Joel M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-02-28

    Pacific Northwest National Laboratory (PNNL) has been tasked to develop a Pilot-scale Plutonium-oxide Processing Unit (P3U) providing a flexible capability to produce 200g (Pu basis) samples of plutonium oxide using different chemical processes for use in identifying and validating nuclear forensics signatures associated with plutonium production. Materials produced can also be used as exercise and reference materials.

  2. In Between Matters : Interfaces in Complex Oxides

    NARCIS (Netherlands)

    van Zalk, M.

    2009-01-01

    Complex oxides are emerging as a versatile class of materials, exhibiting a wide variety of properties. In recent years, it has become increasingly clear that the properties of complex-oxide interfaces can differ considerably from those of the bulk. This opens up the possibility of tuning and

  3. In between matters, interfaces in complex oxides

    NARCIS (Netherlands)

    van Zalk, M.

    2009-01-01

    Complex oxides are emerging as a versatile class of materials, exhibiting a wide variety of properties. In recent years, it has become increasingly clear that the properties of complex-oxide interfaces can differ considerably from those of the bulk. This opens up the possibility of tuning and

  4. Thermochemically active iron titanium oxide materials

    Energy Technology Data Exchange (ETDEWEB)

    Coker, Eric Nicholas; Miller, James E.

    2018-01-16

    A thermal oxidation-reduction cycle is disclosed that uses iron titanium oxide as the reactive material. The cycle may be used for the thermal splitting of water and/or carbon dioxide to form hydrogen and/or carbon monoxide. The formed compounds may be used as syngas precursors to form fuels.

  5. Organic fragments from graphene oxide: Isolation, characterization ...

    Indian Academy of Sciences (India)

    Abstract. As-prepared graphene oxide (GO) contains oxidative debris which can be washed using basic solutions. We present the isolation and characterization of these debris. Dynamic light scattering (DLS) is used to monitor the separation of the debris in various solvents in the presence of different protic and aprotic.

  6. Organic fragments from graphene oxide: Isolation, characterization ...

    Indian Academy of Sciences (India)

    As-prepared graphene oxide (GO) contains oxidative debris which can be washed using basic solutions. We present the isolation and characterization of these debris. Dynamic light scattering (DLS) is used to monitor the separation of the debris in various solvents in the presence of different protic and aprotic alkylamino ...

  7. Subunit mass analysis for monitoring antibody oxidation.

    Science.gov (United States)

    Sokolowska, Izabela; Mo, Jingjie; Dong, Jia; Lewis, Michael J; Hu, Ping

    2017-04-01

    Methionine oxidation is a common posttranslational modification (PTM) of monoclonal antibodies (mAbs). Oxidation can reduce the in-vivo half-life, efficacy and stability of the product. Peptide mapping is commonly used to monitor the levels of oxidation, but this is a relatively time-consuming method. A high-throughput, automated subunit mass analysis method was developed to monitor antibody methionine oxidation. In this method, samples were treated with IdeS, EndoS and dithiothreitol to generate three individual IgG subunits (light chain, Fd' and single chain Fc). These subunits were analyzed by reversed phase-ultra performance liquid chromatography coupled with an online quadrupole time-of-flight mass spectrometer and the levels of oxidation on each subunit were quantitated based on the deconvoluted mass spectra using the UNIFI software. The oxidation results obtained by subunit mass analysis correlated well with the results obtained by peptide mapping. Method qualification demonstrated that this subunit method had excellent repeatability and intermediate precision. In addition, UNIFI software used in this application allows automated data acquisition and processing, which makes this method suitable for high-throughput process monitoring and product characterization. Finally, subunit mass analysis revealed the different patterns of Fc methionine oxidation induced by chemical and photo stress, which makes it attractive for investigating the root cause of oxidation.

  8. Photobiocatalytic alcohol oxidation using LED light sources

    NARCIS (Netherlands)

    Rauch, M.C.R.; Schmidt, S.; Arends, I.W.C.E.; oppelt, K.; Kara, S; Hollmann, F.

    2016-01-01

    The photocatalytic oxidation of NADH using a flavin photocatalyst and a simple blue LED light source is reported. This in situ NAD+ regeneration system can be used to promote biocatalytic, enantioselective oxidation reactions. Compared to the traditional use of white light bulbs this method enables

  9. Relationship Between Oxidative Stress and Preeclampsia in ...

    African Journals Online (AJOL)

    Introduction: Oxidative stress contributes to the pathogenesis of many disease states including preeclampsia. However the degree of change and the precise timing of the tilt from balanced to oxidative stress is not well document in preeclamptic toxaemia of pregnancy in Nigerian women. This underlined the basis of this ...

  10. The Oxides of Nitrogen in Air Pollution.

    Science.gov (United States)

    California State Air Resources Board, Sacramento.

    Research on the health effects of oxides of nitrogen and on the role of oxides of nitrogen in producing photochemical smog effects is presented in this report. Prepared by the California State Department of Public Health at the request of the State Legislature, it gives a comprehensive review of available information, as well as the need for air…

  11. Mathematical Model of Silicon Oxidation in Microelectronics

    Directory of Open Access Journals (Sweden)

    V. A. Bondarev

    2006-01-01

    Full Text Available The paper involves analytical solutions and formulae for determination of the oxide film thickness in the silicon oxidation while using nitride mask. Calculations are based on solutions of a three-dimensional diffusion equation and new mathematical functions that are firstly defined by the author. Suitable analytical and numerical solutions based on the diffusion equation have not yet been obtained

  12. Status of Chronic Oxidation Studies of Graphite

    Energy Technology Data Exchange (ETDEWEB)

    Contescu, Cristian I. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mee, Robert W. [Univ. of Tennessee, Knoxville, TN (United States)

    2016-05-01

    Graphite will undergo extremely slow, but continuous oxidation by traces of moisture that will be present, albeit at very low levels, in the helium coolant of HTGR. This chronic oxidation may cause degradation of mechanical strength and thermal properties of graphite components if a porous oxidation layer penetrates deep enough in the bulk of graphite components during the lifetime of the reactor. The current research on graphite chronic oxidation is motivated by the acute need to understand the behavior of each graphite grade during prolonged exposure to high temperature chemical attack by moisture. The goal is to provide the elements needed to develop predictive models for long-time oxidation behavior of graphite components in the cooling helium of HTGR. The tasks derived from this goal are: (1) Oxidation rate measurements in order to determine and validate a comprehensive kinetic model suitable for prediction of intrinsic oxidation rates as a function of temperature and oxidant gas composition; (2) Characterization of effective diffusivity of water vapor in the graphite pore system in order to account for the in-pore transport of moisture; and (3) Development and validation of a predictive model for the penetration depth of the oxidized layer, in order to assess the risk of oxidation caused damage of particular graphite grades after prolonged exposure to the environment of helium coolant in HTGR. The most important and most time consuming of these tasks is the measurement of oxidation rates in accelerated oxidation tests (but still under kinetic control) and the development of a reliable kinetic model. This report summarizes the status of chronic oxidation studies on graphite, and then focuses on model development activities, progress of kinetic measurements, validation of results, and improvement of the kinetic models. Analysis of current and past results obtained with three grades of showed that the classical Langmuir-Hinshelwood model cannot reproduce all

  13. The influence of environmental conditions on kinetics of arsenite oxidation by manganese-oxides.

    Science.gov (United States)

    Fischel, Matthew H H; Fischel, Jason S; Lafferty, Brandon J; Sparks, Donald L

    2015-01-01

    Manganese-oxides are one of the most important minerals in soil due to their widespread distribution and high reactivity. Despite their invaluable role in cycling many redox sensitive elements, numerous unknowns remain about the reactivity of different manganese-oxide minerals under varying conditions in natural systems. By altering temperature, pH, and concentration of arsenite we were able to determine how manganese-oxide reactivity changes with simulated environmental conditions. The interaction between manganese-oxides and arsenic is particularly important because manganese can oxidize mobile and toxic arsenite into more easily sorbed and less toxic arsenate. This redox reaction is essential in understanding how to address the global issue of arsenic contamination in drinking water. The reactivity of manganese-oxides in ascending order is random stacked birnessite, hexagonal birnessite, biogenic manganese-oxide, acid birnessite, and δ-MnO2. Increasing temperature raised the rate of oxidation. pH had a variable effect on the production of arsenate and mainly impacted the sorption of arsenate on δ-MnO2, which decreased with increasing pH. Acid birnessite oxidized the most arsenic at alkaline and acidic pHs, with decreased reactivity towards neutral pH. The δ-MnO2 showed a decline in reactivity with increasing arsenite concentration, while the acid birnessite had greater oxidation capacity under higher concentrations of arsenite. The batch reactions used in this study quantify the impact of environmental variances on different manganese-oxides' reactivity and provide insight to their roles in governing chemical cycles in the Critical Zone. The reactivity of manganese-oxides investigated was closely linked to each mineral's crystallinity, surface area, and presence of vacancy sites. δ-MnO2 and acid birnessite are thought to be synthetic representatives of naturally occurring biogenic manganese-oxides; however, the biogenic manganese-oxide exhibited a lag time

  14. Nanoroses of nickel oxides: Synthesis, electron tomography study, and application in CO oxidation and energy storage

    KAUST Repository

    Fihri, Aziz

    2012-04-11

    Nickel oxide and mixed-metal oxide structures were fabricated by using microwave irradiation in pure water. The nickel oxide self-assembled into unique rose-shaped nanostructures. These nickel oxide roses were studied by performing electron tomography with virtual cross-sections through the particles to understand their morphology from their interior to their surface. These materials exhibited promising performance as nanocatalysts for CO oxidation and in energy storage devices. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Application of hydrogen injection and oxidation to low temperature solution-processed oxide semiconductors

    Directory of Open Access Journals (Sweden)

    Masashi Miyakawa

    2016-08-01

    Full Text Available Solution-processed oxide semiconductors are promising candidates for the low cost, large scale fabrication of oxide thin-film transistors (TFTs. In this work, a method using hydrogen injection and oxidation (HIO that allows the low temperature solution processing of oxide semiconductors was demonstrated. We found that this method significantly decreases the concentration of residual species while improving the film densification. Additionally, enhanced TFT performance was confirmed following the use of processing temperatures as low as 300 °C. The proposed process is potentially applicable to the fabrication of a wide variety of solution-processed oxide semiconductors.

  16. Proteome oxidative carbonylation during oxidative stress-induced premature senescence of WI-38 human fibroblasts

    DEFF Research Database (Denmark)

    Le Boulch, Marine; Ahmed, Emad K; Rogowska-Wrzesinska, Adelina

    2017-01-01

    Accumulation of oxidatively damaged proteins is a hallmark of cellular and organismal ageing, and is also a phenotypic feature shared by both replicative senescence and stress-induced premature senescence of human fibroblasts. Moreover, proteins that are building up as oxidized (i.e. the "Oxi......-proteome") during ageing and age-related diseases represent a restricted set of cellular proteins, indicating that certain proteins are more prone to oxidative carbonylation and subsequent intracellular accumulation. The occurrence of specific carbonylated proteins upon oxidative stress induced premature senescence...... to belong to functional interaction networks pointing to signalling pathways that have been implicated in the oxidative stress response and subsequent premature senescence....

  17. Strong, damage tolerant oxide-fiber/oxide matrix composites

    Science.gov (United States)

    Bao, Yahua

    Electrophoretic deposition (EPD) is an easy and cost effective method to fabricate fiber-reinforced green composites. Non-conductive Nextel(TM) 720 fibers were successfully coated with a transient, conductive polypyrrole submicron surface layer for use directly as an electrode in EPD processing. However, electric-field shielding limits particle infiltration into the conductive fiber bundles and they mostly deposit on the outer surface of the fiber bundle. When the bundle is large, central cavities exist after deposition. The EPD cell was modified for electrophoretic infiltration deposition (EPID). Non conductive fibers were laid on an electrode and charged particles in an ethanol suspension are driven there through by an electric field, infiltrate and deposit on the electrode to then build up into the fiber preform and fill the voids therein. Dense, uniform, green fiber composites were successfully fabricated via constant current EPID. The EPID process is modeled as capillary electrophoretic infiltration. The process consists of two steps: particle electrophoresis outside the capillaries and electrophoretic infiltration inside the capillaries. Due to the zero net flow of the ethanol across the capillary cross-section, there is no electro-osmotic flow contribution to the deposition rate. Hamaker's law was extended to the EPID process, i.e., the deposition yield is proportional to the electric field inside the capillaries. The total deposition yield is controlled by the slow step of the process, i.e., the rate of electrophoresis in the open suspension outside the capillaries. AlPO4 was proposed as a weak layer between oxide fibers and oxide matrix in fiber-reinforced ceramic matrix composites (CMC's). AlPO 4 nano particles were synthesized by chemical co-precipitation of Al 3+ and HPO42- with urea at 95°C. The solution pH basic region and amorphous AlPO4 precipitated of narrow size distribution with a mean particle size 50nm. Nextel 720 fibers were pretreated with

  18. Impact of oxidative stress on female fertility

    Science.gov (United States)

    Ruder, Elizabeth H.; Hartman, Terryl J.; Goldman, Marlene B.

    2009-01-01

    Purpose of review To review the role of oxidative stress in the context of female fertility. Recent findings Oxidative stress is associated with decreased female fertility in animal and in-vitro models, but no studies to date have directly assessed the relationship in women. Exposures associated with oxidative stress and with evidence to influence the timing and maintenance of a viable pregnancy include pregnancy complications (e.g. preeclampsia), extremes of body weight, alcohol, tobacco, and caffeine intake. Intake of antioxidant nutrients, including use of multivitamins, impacts the generation of reactive oxygen species and may play a beneficial role in female fertility. Summary Infertility is a significant public health problem and diagnosis and treatment are stressful, invasive, and costly. The role of oxidative stress in female fertility is an understudied and compelling area for investigation. Identifying modifiable factors to decrease oxidative stress in the gynecologic environment may be an inexpensive and noninvasive therapy for increasing fertility. PMID:19469044

  19. Heterogeneous Metal Catalysts for Oxidation Reactions

    Directory of Open Access Journals (Sweden)

    Md. Eaqub Ali

    2014-01-01

    Full Text Available Oxidation reactions may be considered as the heart of chemical synthesis. However, the indiscriminate uses of harsh and corrosive chemicals in this endeavor are threating to the ecosystems, public health, and terrestrial, aquatic, and aerial flora and fauna. Heterogeneous catalysts with various supports are brought to the spotlight because of their excellent capabilities to accelerate the rate of chemical reactions with low cost. They also minimize the use of chemicals in industries and thus are friendly and green to the environment. However, heterogeneous oxidation catalysis are not comprehensively presented in literature. In this short review, we clearly depicted the current state of catalytic oxidation reactions in chemical industries with specific emphasis on heterogeneous catalysts. We outlined here both the synthesis and applications of important oxidation catalysts. We believe it would serve as a reference guide for the selection of oxidation catalysts for both industries and academics.

  20. Clinical Relevance of Biomarkers of Oxidative Stress

    DEFF Research Database (Denmark)

    Frijhoff, Jeroen; Winyard, Paul G; Zarkovic, Neven

    2015-01-01

    SIGNIFICANCE: Oxidative stress is considered to be an important component of various diseases. A vast number of methods have been developed and used in virtually all diseases to measure the extent and nature of oxidative stress, ranging from oxidation of DNA to proteins, lipids, and free amino...... acids. RECENT ADVANCES: An increased understanding of the biology behind diseases and redox biology has led to more specific and sensitive tools to measure oxidative stress markers, which are very diverse and sometimes very low in abundance. CRITICAL ISSUES: The literature is very heterogeneous....... It is often difficult to draw general conclusions on the significance of oxidative stress biomarkers, as only in a limited proportion of diseases have a range of different biomarkers been used, and different biomarkers have been used to study different diseases. In addition, biomarkers are often measured...

  1. Biological nitric oxide signalling: chemistry and terminology.

    Science.gov (United States)

    Heinrich, Tassiele A; da Silva, Roberto S; Miranda, Katrina M; Switzer, Christopher H; Wink, David A; Fukuto, Jon M

    2013-08-01

    Biological nitrogen oxide signalling and stress is an area of extreme clinical, pharmacological, toxicological, biochemical and chemical research interest. The utility of nitric oxide and derived species as signalling agents is due to their novel and vast chemical interactions with a variety of biological targets. Herein, the chemistry associated with the interaction of the biologically relevant nitrogen oxide species with fundamental biochemical targets is discussed. Specifically, the chemical interactions of nitrogen oxides with nucleophiles (e.g. thiols), metals (e.g. hemeproteins) and paramagnetic species (e.g. dioxygen and superoxide) are addressed. Importantly, the terms associated with the mechanisms by which NO (and derived species) react with their respective biological targets have been defined by numerous past chemical studies. Thus, in order to assist researchers in referring to chemical processes associated with nitrogen oxide biology, the vernacular associated with these chemical interactions is addressed. © 2013 The British Pharmacological Society.

  2. Oxidation as "the stress of life".

    Science.gov (United States)

    Malinin, Nikolay L; West, Xiaoxia Z; Byzova, Tatiana V

    2011-09-01

    Multiple biological consequences of oxidative stress are known to contribute to aging and aging-related pathologies. It was recently shown that (carboxyalkyl)pyrroles (CAPs), the end products of phospholipid oxidation serve as a novel class of endogenous ligands for Toll-like receptors (TLRs) and promote the process of angiogenesis. In this review, we discuss implications of these findings in the context of age-related pathologies, including tumorigenesis. Accumulation of oxidation products in tissues of aging organisms might create conditions for uncontrolled pathological angiogenesis as seen in patients with age related macular degeneration. CAPs and their receptors, TLRs might also promote the progression of atherosclerotic lesions. Importantly, besides their role in a number of pathologies, oxidative products of phospholipids contribute to tissue repair processes thereby antagonizing the destructive effects of oxidation.

  3. Oxidative Stress Related Diseases in Newborns

    Directory of Open Access Journals (Sweden)

    Yasemin Ozsurekci

    2016-01-01

    Full Text Available We review oxidative stress-related newborn disease and the mechanism of oxidative damage. In addition, we outline diagnostic and therapeutic strategies and future directions. Many reports have defined oxidative stress as an imbalance between an enhanced reactive oxygen/nitrogen species and the lack of protective ability of antioxidants. From that point of view, free radical-induced damage caused by oxidative stress seems to be a probable contributing factor to the pathogenesis of many newborn diseases, such as respiratory distress syndrome, bronchopulmonary dysplasia, periventricular leukomalacia, necrotizing enterocolitis, patent ductus arteriosus, and retinopathy of prematurity. We share the hope that the new understanding of the concept of oxidative stress and its relation to newborn diseases that has been made possible by new diagnostic techniques will throw light on the treatment of those diseases.

  4. A thermodynamic structural model of graphene oxide

    Science.gov (United States)

    Luo, Haining; Auchterlonie, Graeme; Zou, Jin

    2017-10-01

    Graphene oxide is an easy-to-make material that has a similar structure with graphene. However, the real structure of graphene oxide is still controversial, and an accurate structural model is crucial for understanding its various properties. In this study, by using molecular mechanics and density functional theory, we introduce a thermodynamically favorable structural model of graphene oxide with chemical composition variable from C1.5O to C2.5O . We also calculate their theoretical Raman spectra and electronic properties. It has been found that, in the proposed graphene oxide structure, the para-substituted epoxide groups stay in close proximity to the hydroxyl, but on the opposite sides of the carbon sheet. In addition, on the edge of graphene oxide sheet, the carboxyl prefers attachment in the armchair orientation, while the carbonyl prefers the zigzag orientation.

  5. Biological nitric oxide signalling: chemistry and terminology

    Science.gov (United States)

    Heinrich, Tassiele A; da Silva, Roberto S; Miranda, Katrina M; Switzer, Christopher H; Wink, David A; Fukuto, Jon M

    2013-01-01

    Biological nitrogen oxide signalling and stress is an area of extreme clinical, pharmacological, toxicological, biochemical and chemical research interest. The utility of nitric oxide and derived species as signalling agents is due to their novel and vast chemical interactions with a variety of biological targets. Herein, the chemistry associated with the interaction of the biologically relevant nitrogen oxide species with fundamental biochemical targets is discussed. Specifically, the chemical interactions of nitrogen oxides with nucleophiles (e.g. thiols), metals (e.g. hemeproteins) and paramagnetic species (e.g. dioxygen and superoxide) are addressed. Importantly, the terms associated with the mechanisms by which NO (and derived species) react with their respective biological targets have been defined by numerous past chemical studies. Thus, in order to assist researchers in referring to chemical processes associated with nitrogen oxide biology, the vernacular associated with these chemical interactions is addressed. PMID:23617570

  6. A role of electrons in zirconium oxidation

    Directory of Open Access Journals (Sweden)

    Alekseev Pavel N.

    2017-01-01

    Full Text Available Growing the oxide scale on the zirconium cladding of fuel elements in pressured-water reactors (PWR is caused by the current of oxygen anions off the waterside to the metal through the layer of zirconia and by the strictly equal inverse electronic current. This process periodically speeds up the corrosion of the zirconium cladding in the aqueous coolant due to the breakaway of the dense part of oxide scale when its thickness reaches 2 mkm. It is shown that the electronic resistivity of zirconia is not limiting the zirconium oxidation at working temperatures. For gaining this limitation, a metal of lesser valence than zirconium has to be added to this oxide scale up to 15%. Then, oxygen vacancies arise in the complex zirconia, increase its band-gap, and thus, sharply decrease the electronic conductivity and form the solid oxide electrolyte whose growth is inhibited in contact with water at working temperatures of PWR.

  7. Fabrication and properties of erbium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Neuman, A.; Platero, M.; Romero, R.; McClellan, K.J.; Petrovic, J.J.

    1997-03-01

    Erbium oxide (Er{sub 2}O{sub 3}) is a rare earth oxide of interest because of its chemical and thermal stability and high melting point, 2,430 C. However, there is relatively little information available regarding the relation between the structure and the mechanical properties of this material. A densification study of polycrystalline erbium oxide powders is reported here. Erbium oxide pellets were uniaxially pressed (40--280 MPa) and sintered (1,500--1,800 C) in order to obtain density data for as-received commercial powders. In addition, the particle size and distribution of as-received powders were varied by milling and the effects on densification were studied. The powders were characterized for particle size, phase and impurity content and surface area. The mechanical properties of high density sintered erbium oxide bodies were characterized using indentation hardness and toughness as a function of temperature and microstructure. Relations between the microstructure and mechanical properties are described.

  8. Laser induced single spot oxidation of titanium

    Energy Technology Data Exchange (ETDEWEB)

    Jwad, Tahseen, E-mail: taj355@bham.ac.uk; Deng, Sunan; Butt, Haider; Dimov, S.

    2016-11-30

    Highlights: • A new high resolution laser induced oxidation (colouring) method is proposed (single spot oxidation). • The method is applied to control oxide films thicknesses and hence colours on titanium substrates in micro-scale. • The method enable imprinting high resolution coloured image on Ti substrate. • Optical and morphological periodic surface structures are also produced by an array of oxide spots using the proposed method. • Colour coding of two colours into one field is presented. - Abstract: Titanium oxides have a wide range of applications in industry, and they can be formed on pure titanium using different methods. Laser-induced oxidation is one of the most reliable methods due to its controllability and selectivity. Colour marking is one of the main applications of the oxidation process. However, the colourizing process based on laser scanning strategies is limited by the relative large processing area in comparison to the beam size. Single spot oxidation of titanium substrates is proposed in this research in order to increase the resolution of the processed area and also to address the requirements of potential new applications. The method is applied to produce oxide films with different thicknesses and hence colours on titanium substrates. High resolution colour image is imprinted on a sheet of pure titanium by converting its pixels’ colours into laser parameter settings. Optical and morphological periodic surface structures are also produced by an array of oxide spots and then analysed. Two colours have been coded into one field and the dependencies of the reflected colours on incident and azimuthal angles of the light are discussed. The findings are of interest to a range of application areas, as they can be used to imprint optical devices such as diffusers and Fresnel lenses on metallic surfaces as well as for colour marking.

  9. Oxidation behaviour of boron carbide powder

    Energy Technology Data Exchange (ETDEWEB)

    Li, Y.Q. [College of Materials Science and Engineering, Nanjing University of Technology, New Model Road 5, Nanjing, Jiangsu 210009 (China)]. E-mail: Li.Yuanqiang@nims.go.jp; Qiu, T. [College of Materials Science and Engineering, Nanjing University of Technology, New Model Road 5, Nanjing, Jiangsu 210009 (China)

    2007-01-25

    Isothermal oxidation behaviour of powdered boron carbide (B{sub 4}C) with the fine (1.52 {mu}m), medium (22.5 {mu}m) and coarse (59.6 {mu}m) particle size has been studied in air ranging from 500 to 800 deg. C. The oxidation rate strongly depends on the particle size of boron carbide and temperature. The smaller particle size the higher oxidation rate of B{sub 4}C powder due to its larger surface area. When B{sub 4}C powder is oxidized in air, a B{sub 2}O{sub 3} glass film is formed on the surface of B{sub 4}C grain which retards the further oxidation reaction. The oxidation kinetics is approximately fitted to the diffusion-controlled rate law which can be described by the Jander's equation. The apparent activation energy for the fine-, medium- and coarse-B{sub 4}C powders is 209.4 {+-} 11.4, 212.7 {+-} 35.8 and 219.2 {+-} 45.3 kJ mol{sup -1}, respectively, slightly varying with the impurity content of B{sub 4}C powders. The type of rate law suggests that the diffusion of oxygen through the oxide layer is the rate-limiting step in the oxidation reactions. In addition, the change in the oxidation process at higher oxidation fraction might associate with the B{sub 2}O{sub 3} volatilization at higher temperatures.

  10. Carbon monoxide oxidation over three different states of copper: Development of a model metal oxide catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Jernigan, Glenn Geoffrey [California Univ., Berkeley, CA (United States). Dept. of Chemistry

    1994-10-01

    Carbon monoxide oxidation was performed over the three different oxidation states of copper -- metallic (Cu), copper (I) oxide (Cu2O), and copper (II) oxide (CuO) as a test case for developing a model metal oxide catalyst amenable to study by the methods of modern surface science and catalysis. Copper was deposited and oxidized on oxidized supports of aluminum, silicon, molybdenum, tantalum, stainless steel, and iron as well as on graphite. The catalytic activity was found to decrease with increasing oxidation state (Cu > Cu2O > CuO) and the activation energy increased with increasing oxidation state (Cu, 9 kcal/mol < Cu2O, 14 kcal/mol < CuO, 17 kcal/mol). Reaction mechanisms were determined for the different oxidation states. Lastly, NO reduction by CO was studied. A Cu and CuO catalyst were exposed to an equal mixture of CO and NO at 300--350 C to observe the production of N2 and CO2. At the end of each reaction, the catalyst was found to be Cu2O. There is a need to study the kinetics of this reaction over the different oxidation states of copper.

  11. In vivo oxidation and surface damage in retrieved ethylene oxide-sterilized total knee arthroplasties.

    Science.gov (United States)

    MacDonald, Daniel; Hanzlik, Josa; Sharkey, Peter; Parvizi, Javad; Kurtz, Steven M

    2012-07-01

    Gas sterilization (eg, ethylene oxide [EtO] and gas plasma) was introduced for polyethylene to reduce oxidation due to free radicals occurring during radiation sterilization. Recently, oxidation has been observed in polyethylenes with undetectable levels of free radicals, which were expected to be oxidatively stable. It is unclear whether in vivo oxidation will occur in unirradiated inserts sterilized with EtO. We analyzed the oxidation, mechanical behavior, and surface damage mechanisms of tibial inserts of a single design sterilized using EtO. We collected 20 EtO-sterilized tibial inserts at revision surgeries. We assessed oxidative using Fourier transform infrared spectroscopy and mechanical properties using the small punch test. Surface damage was assessed using damage scoring techniques and micro-CT. Oxidation indexes were low and uniform between the regions. The subtle changes did not affect the mechanical properties of the polymer. The dominant surface damage modes included burnishing, abrasion, and third-body wear. There was no evidence of delamination in the retrievals. The retrieved EtO-sterilized UHMWPE retrievals remained stable with respect to both oxidative and mechanical properties for up to 10 years in vivo. We did observe slight measurable amounts of oxidation in the inserts; however, it was far below levels that would be expected to compromise the strength of the polymer. Due to the stable oxidative and mechanical properties, EtO-sterilized tibial components appear to be an effective alternative to gamma-sterilized inserts, at least in short-term implantations.

  12. Synthesis and characterization of different metal oxide nanostructures by simple electrolysis based oxidation of metals.

    Science.gov (United States)

    Singh, Dinesh Pratap; Srivastava, Onkar Nath

    2009-09-01

    We report the Synthesis of different metal oxide (Cu2O, SnO2, Fe3O4 and PbO2) nanostructures by simple electrolysis based oxidation of metals (Cu, Sn, Fe and Pb). We have utilized the two electrode set up for the electrolysis and used different metal electrodes as anode and platinum as cathode. The synthesized nanomaterials were delaminated in the electrolyte. The microstructural characterization of synthesized materials in electrolytes after electrolysis at different electrode potentials revealed that the nanostructures strongly depend on the applied voltage between the electrodes. Various nanostructures (nanothreads, nanowires, nanocubes, nanotetrapods and hexagons-like) of metal oxides have been synthesized by this method. In case of copper electrode we have found nanothreads and nanowires of cuprous oxide. Tin electrode resulted nanothreads, nanotetrapod and nanocube like structures of tin oxide. Iron electrode resulted, nanowire like structures of iron oxide and lead sheet transformed into hexagon like and six petals like structures of lead oxide.

  13. Novel synthesis and shape-dependent catalytic performance of Cu-Mn oxides for CO oxidation

    Science.gov (United States)

    Li, Zhixun; Wang, Honglei; Wu, Xingxing; Ye, Qinglan; Xu, Xuetang; Li, Bin; Wang, Fan

    2017-05-01

    Transition metal oxides with large specific surface area are attractive for high-activity catalysts, and hierarchical structures of transition metal oxides with porous feature possess the structural advantage in the transfer of gaseous reactant and product. In this work, porous Cu-Mn oxides with high surface area were successfully obtained through low-temperature coprecipitation method in alcohol/water solvent and then post-annealing. The addition of alcohol showed great influences on the shape and catalytic performances for CO oxidation. Dumbbell-like Cu-Mn oxide particles with splitting ends displayed high catalytic activity and a complete conversion of CO was achieved at 45 °C, suggesting a shape-dependent catalytic activity. The oxidative activity was attributed to a combination of factors including specific surface area, active surface oxygen species and Mn(IV) cations. The results may supply a new thought to design high-performance Cu-Mn oxide catalysts.

  14. Substrate overload: Glucose oxidation in human myotubes conquers palmitate oxidation through anaplerosis

    DEFF Research Database (Denmark)

    Gaster, Michael

    2009-01-01

    by increasing concentrations of the other in human myotubes established from healthy, lean subjects exposed to acute stepwise increases in glucose and PA levels. At high substrate levels; PA oxidation was reduced while release of acid soluble metabolites was increased and, both glucose oxidation and release...... of citrate was increased which could be abolished by phenylacetic acid (inhibitor of pyruvate carboxylase (PC)). The present data challenges above preconceptions. Although they operate at low-moderate substrate levels additional two principles determine substrate oxidation at higher substrate concentrations......To date, two cardinal principles govern oxidation of glucose and fatty acids in skeletal muscle; exogenous fatty acid reduces glucose oxidation and glucose reduces fatty acid oxidation. Both glucose and palmitate (PA) oxidation was increased by increasing their concentration and inhibited...

  15. Oxidation of Lead Frame Copper Alloys with Different Compositions and Its Effect on Oxide Film Adhesion

    Science.gov (United States)

    Chen, Xi; Hu, Anmin; Li, Ming; Mao, Dali

    2009-02-01

    Oxidation of four typical lead frame copper alloys was investigated. The oxidation rate and adhesion strength of oxide films to copper alloy substrates were studied by measuring the thickness and carrying out peel tests. The results show that, although copper alloys C5191 and C7025 have thinner oxide films, a lower adhesion strength and a higher proportion of CuO were obtained than in the other copper alloys EFTEC64T and C194. The adhesion strength is mainly influenced by the structure of the oxide film of the copper alloys, especially the CuO/Cu2O ratio in the film. The highest adhesion strength is obtained for the copper oxide film with a basic structure of CuO/Cu2O/Cu and a CuO/Cu2O ratio of about 0.1. The segregation of additional elements in the copper alloy plays an important role in the oxide film structure.

  16. Oxidation of artificial sweetener sucralose by advanced oxidation processes: a review.

    Science.gov (United States)

    Sharma, Virender K; Oturan, Mehmet; Kim, Hyunook

    2014-01-01

    Sucralose, a chlorinated carbohydrate, has shown its increased use as an artificial sweetener and persistently exists in wastewater treatment plant effluents and aquatic environment. This paper aims to review possible degradation of sucralose and related carbohydrates by biological, electrochemical, chemical, and advanced oxidation processes. Biodegradation of sucralose in waterworks did not occur significantly. Electrochemical oxidation of carbohydrates may be applied to seek degradation of sucralose. The kinetics of the oxidation of sucralose and the related carbohydrates by different oxidative species is compared. Free chlorine, ozone, and ferrate did not show any potential to degrade sucralose in water. Advanced oxidation processes, generating highly strong oxidizing agent hydroxyl radicals ((•)OH), have demonstrated effectiveness in transforming sucralose in water. The mechanism of oxidation of sucralose by (•)OH is briefly discussed.

  17. Anti-oxidant effect of flavonoids on the susceptibility of LDL oxidation.

    Science.gov (United States)

    Naderi, Gholam Ali; Asgary, Seddigheh; Sarraf-Zadegan, Nizal; Shirvany, Hamid

    2003-04-01

    In vitro studies have demonstrated increased atherogenicity of oxidized low-density lipoprotein (ox-LDL) compared to native LDL. Oxidative modification of LDL alters its structure allowing LDL to be taken up by scavenger receptors on macrophage, endothelial, and smooth muscle cells, leading to the formation of lipid-laden foam cells, the hallmark of early atherosclerotic lesions. The susceptibility of LDL to in vitro oxidation was assessed essentially by the technique described by Esterbauer et al. LDL oxidation were monitored by change in 234-absorbance in the presence and absence of pure flavonoids. Morin, genistein, apigenin and biochanin A, naringin and quercetin were used at different concentration. These flavonoids significantly inhibit in vitro LDL oxidation, genistein, morin and naringin have stronger inhibitory activity against LDL oxidation than biochanin A or apigenin. This study show that flavonoids prevent in vitro LDL oxidation and probably would be important to prevent atherosclerosis.

  18. Catalytic Activity of Oxidized Carbon Black and Graphene Oxide for the Crosslinking of Epoxy Resins

    Directory of Open Access Journals (Sweden)

    Maria Rosaria Acocella

    2017-04-01

    Full Text Available This article compares the catalytic activities of oxidized carbon black (oCB and graphene oxide (eGO samples on the kinetics of a reaction of diglycidyl ether of bisphenol A (DGEBA with a diamine, leading to crosslinked insoluble networks. The study is mainly conducted by rheometry and Differential Scanning Calorimetry (DSC. Following the same oxidation procedure, CB samples are more efficiently oxidized than graphite samples. For instance, CB and graphite samples with high specific surface areas (151 and 308 m2/g, as oxidized by the Hummers’ method, exhibit O/C wt/wt ratios of 0.91 and 0.62, respectively. Due to the higher oxidation levels, these oCB samples exhibit a higher catalytic activity toward the curing of epoxy resins than fully exfoliated graphene oxide.

  19. Structural, electronic and chemical properties of metal/oxide and oxide/oxide interfaces and thin film structures

    Energy Technology Data Exchange (ETDEWEB)

    Lad, Robert J.

    1999-12-14

    This project focused on three different aspects of oxide thin film systems: (1) Model metal/oxide and oxide/oxide interface studies were carried out by depositing ultra-thin metal (Al, K, Mg) and oxide (MgO, AlO{sub x}) films on TiO{sub 2}, NiO and {alpha}-Al{sub 2}O{sub 3} single crystal oxide substrates. (2) Electron cyclotron resonance (ECR) oxygen plasma deposition was used to fabricate AlO{sub 3} and ZrO{sub 2} films on sapphire substrates, and film growth mechanisms and structural characteristics were investigated. (3) The friction and wear characteristics of ZrO{sub 2} films on sapphire substrates in unlubricated sliding contact were studied and correlated with film microstructure. In these studies, thin film and interfacial regions were characterized using diffraction (RHEED, LEED, XRD), electron spectroscopies (XPS, UPS, AES), microscopy (AFM) and tribology instruments (pin-on-disk, friction microprobe, and scratch tester). By precise control of thin film microstructure, an increased understanding of the structural and chemical stability of interface regions and tribological performance of ultra-thin oxide films was achieved in these important ceramic systems.

  20. 40 CFR 52.1877 - Control strategy: Photochemical oxidants (hydrocarbons).

    Science.gov (United States)

    2010-07-01

    ... oxidants (hydrocarbons). 52.1877 Section 52.1877 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY....1877 Control strategy: Photochemical oxidants (hydrocarbons). (a) The requirements of Subpart G of this... national standard for photochemical oxidants (hydrocarbons) in the Metropolitan Cincinnati interstate...

  1. Effects of glutathione, Trolox and desferrioxamine on hemoglobin-induced protein oxidative damage: anti-oxidant or pro-oxidant?

    Science.gov (United States)

    Lu, Naihao; Chen, Wei; Peng, Yi-Yuan

    2011-06-01

    Evidence to support the role of heme proteins as major inducers of oxidative damage is increasingly present. Antioxidants have been widely used to ameliorate oxidative damage in vivo and in vitro, where the mechanism of this therapeutic action was usually dependent on their anti-oxidant effects. In this study, we chose three classic antioxidants, i.e. glutathione (GSH, an important intracellular antioxidant), 6-hydroxy-2, 5, 7, 8-tetramethylchroman-2-carboxylic acid (Trolox, a phenolic antioxidant without chelating effect) and desferrioxamine (DFO, a good iron chelator), to study their efficiencies on hemoglobin-induced protein oxidative damage. It was found that all of these antioxidants had the capacities to act as free radical scavengers and reducing agents to remove cytotoxic ferryl hemoglobin, demonstrating apparent anti-oxidant activities. However, the effects on hemoglobin-H(2)O(2)-induced protein oxidation depended on the categories and concentrations of antioxidants. GSH efficiently inhibited protein (bovine serum albumin or rat heart homogenate) carbonyl formation in a dose-dependent manner. In contrast to their protective effects at high concentrations, both Trolox and DFO could significantly aggravate protein oxidation at low concentrations. The pro-oxidant effects of Trolox and DFO on hemoglobin-mediated oxidative damage were probably related to their abilities in producing additional free radicals, such as superoxide (O·(2)(-)) and hydroxyl radical (·OH). The dual effects on hemoglobin redox reactions may provide new insights into the physiological implications of Trolox and DFO with cellular heme proteins. Copyright © 2011 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

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

    2014-05-01

    Water oxidation in the neutral pH regime catalyzed by amorphous transition-metal oxides is of high interest in energy science. Crucial determinants of electrocatalytic activity were investigated for a cobalt-based oxide film electrodeposited at various thicknesses on inert electrodes. For water oxidation at low current densities, the turnover frequency (TOF) per cobalt ion of the bulk material stayed fully constant for variation of the thickness of the oxide film by a factor of 100 (from about 15 nm to 1.5 μm). Thickness variation changed neither the nanostructure of the outer film surface nor the atomic structure of the oxide catalyst significantly. These findings imply catalytic activity of the bulk hydrated oxide material. Nonclassical dependence on pH was observed. For buffered electrolytes with pKa values of the buffer base ranging from 4.7 (acetate) to 10.3 (hydrogen carbonate), the catalytic activity reflected the protonation state of the buffer base in the electrolyte solution directly and not the intrinsic catalytic properties of the oxide itself. It is proposed that catalysis of water oxidation occurs within the bulk hydrated oxide film at the margins of cobalt oxide fragments of molecular dimensions. At high current densities, the availability of a proton-accepting base at the catalyst-electrolyte interface controls the rate of water oxidation. The reported findings may be of general relevance for water oxidation catalyzed at moderate pH by amorphous transition-metal oxides. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Gold nanoparticles supported on magnesium oxide for CO oxidation

    Directory of Open Access Journals (Sweden)

    Bogdanchikova Nina

    2011-01-01

    Full Text Available Abstract Au was loaded (1 wt% on a commercial MgO support by three different methods: double impregnation, liquid-phase reductive deposition and ultrasonication. Samples were characterised by adsorption of N2 at -96°C, temperature-programmed reduction, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. Upon loading with Au, MgO changed into Mg(OH2 (the hydroxide was most likely formed by reaction with water, in which the gold precursor was dissolved. The size range for gold nanoparticles was 2-12 nm for the DIM method and 3-15 nm for LPRD and US. The average size of gold particles was 5.4 nm for DIM and larger than 6.5 for the other methods. CO oxidation was used as a test reaction to compare the catalytic activity. The best results were obtained with the DIM method, followed by LPRD and US. This can be explained in terms of the nanoparticle size, well known to determine the catalytic activity of gold catalysts.

  4. Emergent Phenomena at Oxide Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, H.Y.

    2012-02-16

    Transition metal oxides (TMOs) are an ideal arena for the study of electronic correlations because the s-electrons of the transition metal ions are removed and transferred to oxygen ions, and hence the strongly correlated d-electrons determine their physical properties such as electrical transport, magnetism, optical response, thermal conductivity, and superconductivity. These electron correlations prohibit the double occupancy of metal sites and induce a local entanglement of charge, spin, and orbital degrees of freedom. This gives rise to a variety of phenomena, e.g., Mott insulators, various charge/spin/orbital orderings, metal-insulator transitions, multiferroics, and superconductivity. In recent years, there has been a burst of activity to manipulate these phenomena, as well as create new ones, using oxide heterostructures. Most fundamental to understanding the physical properties of TMOs is the concept of symmetry of the order parameter. As Landau recognized, the essence of phase transitions is the change of the symmetry. For example, ferromagnetic ordering breaks the rotational symmetry in spin space, i.e., the ordered phase has lower symmetry than the Hamiltonian of the system. There are three most important symmetries to be considered here. (i) Spatial inversion (I), defined as r {yields} -r. In the case of an insulator, breaking this symmetry can lead to spontaneous electric polarization, i.e. ferroelectricity, or pyroelectricity once the point group belongs to polar group symmetry. (ii) Time-reversal symmetry (T) defined as t {yields} -t. In quantum mechanics, the time-evolution of the wave-function {Psi} is given by the phase factor e{sup -iEt/{h_bar}} with E being the energy, and hence time-reversal basically corresponds to taking the complex conjugate of the wave-function. Also the spin, which is induced by the 'spinning' of the particle, is reversed by time-reversal. Broken T-symmetry is most naturally associated with magnetism, since the

  5. Electro Catalytic Oxidation (ECO) Operation

    Energy Technology Data Exchange (ETDEWEB)

    Morgan Jones

    2011-03-31

    The power industry in the United States is faced with meeting many new regulations to reduce a number of air pollutants including sulfur dioxide, nitrogen oxides, fine particulate matter, and mercury. With over 1,000 power plants in the US, this is a daunting task. In some cases, traditional pollution control technologies such as wet scrubbers and SCRs are not feasible. Powerspan's Electro-Catalytic Oxidation, or ECO{reg_sign} process combines four pollution control devices into a single integrated system that can be installed after a power plant's particulate control device. Besides achieving major reductions in emissions of sulfur dioxide (SO{sub 2}), nitrogen oxides (NOx), fine particulate matter (PM2.5) and mercury (Hg), ECO produces a highly marketable fertilizer, which can help offset the operating costs of the process system. Powerspan has been operating a 50-MW ECO commercial demonstration unit (CDU) at FirstEnergy Corp.'s R.E. Burger Plant near Shadyside, Ohio, since February 2004. In addition to the CDU, a test loop has been constructed beside the CDU to demonstrate higher NOx removal rates and test various scrubber packing types and wet ESP configurations. Furthermore, Powerspan has developed the ECO{reg_sign}{sub 2} technology, a regenerative process that uses a proprietary solvent to capture CO{sub 2} from flue gas. The CO{sub 2} capture takes place after the capture of NOx, SO{sub 2}, mercury, and fine particulate matter. Once the CO{sub 2} is captured, the proprietary solution is regenerated to release CO{sub 2} in a form that is ready for geological storage or beneficial use. Pilot scale testing of ECO{sub 2} began in early 2009 at FirstEnergy's Burger Plant. The ECO{sub 2} pilot unit is designed to process a 1-MW flue gas stream and produce 20 tons of CO{sub 2} per day, achieving a 90% CO{sub 2} capture rate. The ECO{sub 2} pilot program provided the opportunity to confirm process design and cost estimates, and prepare for large

  6. Recent developments in complex metal oxide photoelectrodes

    Science.gov (United States)

    Abdi, Fatwa F.; Berglund, Sean P.

    2017-05-01

    Photoelectrochemical (PEC) water splitting, a process that directly produces hydrogen from water and sunlight using semiconductor materials, is an attractive form of renewable energy production. The hydrogen that is produced can be easily transported, stored, and utilized as a fuel without the emission of greenhouse gasses. However, many scientific and engineering challenges need to be overcome before PEC water splitting can be implemented on a large scale. One of the biggest challenges is the identification of suitable semiconductor materials to use in the construction of photoelectrodes. This topical review highlights a promising class of materials, complex metal oxides, which can be used as photoelectrodes for PEC water splitting. The advantages and limitations of complex metal oxides are first discussed, and strategies to overcome the limitations are outlined using the model case of bismuth vanadate (BiVO4), one of the highest performing complex metal oxide photoanodes reported to date. Building on the success story of BiVO4, we discuss pathways towards achieving even higher water splitting performance, including bandgap engineering as well as the development of alternative complex metal oxides with more appropriate bandgaps for obtaining high solar-to-hydrogen efficiency. Several classes of complex metal oxides (e.g. delafossites, tungstates, vanadates, spinels) are presented as promising candidates for photoelectrode materials. Finally, we conclude by summarizing the key properties of these complex metal oxides and providing an outlook towards expedited discovery of new and novel complex metal oxides for use as photoelectrodes.

  7. Oxidative stress in children with neurocysticercosis.

    Science.gov (United States)

    Prasad, Rajniti; Anil; Mishra, Om P; Mishra, Surendra P; Upadhyay, Ram S; Singh, Tej B

    2012-10-01

    Free radicals can cause neuronal injury and play an important role in pathogenesis of neurocysticercosis. This study was done to evaluate oxidative stress (antioxidants and oxidants) in cerebrospinal fluid (CSF) of children with neurocysticercosis and to observe their correlation with the type of seizure and outcome. Forty consecutive confirmed cases of neurocysticercosis were evaluated for their markers of reactive oxygen species, that is, oxidants (malondialdehyde, protein carbonyl and nitrite) and antioxidant (superoxide dismutase, glutathione peroxidase, ceruloplasmin, ascorbic acid, copper and zinc) concentrations in CSF. An equal number of children, age and sex matched with an idiopathic generalized tonic-clonic seizure, were studied as controls. Generalized tonic-clonic seizure (65%) was the most common presentation, and a single ring-enhancing lesion in the parietal lobe was the most common finding in cranial imaging. Oxidants such as malondialdehyde, protein carbonyl and nitrite in CSF were significantly elevated (P neurocysticercosis than in controls. There were insignificant differences in oxidant and antioxidant value in CSF in relation to the type of seizure, number and location of lesion in cerebral cortex and antiepileptic therapy. The significantly elevated malondialdehyde, nitrite and protein carbonyl values reflect increased oxidative stress, whereas decreased concentrations of glutathione peroxidase, ascorbic acid, zinc, copper, ceruloplasmin and superoxide dismutase point toward utilization of the antioxidants in neurocysticercosis. The observed changes in oxidants and antioxidants suggest the production of reactive oxygen species such as superoxide, hydrogen peroxides and hydroxyl radicals and their possible role in pathogenesis of neurocysticercosis.

  8. Oxidative stress and the ageing endocrine system.

    Science.gov (United States)

    Vitale, Giovanni; Salvioli, Stefano; Franceschi, Claudio

    2013-04-01

    Ageing is a process characterized by a progressive decline in cellular function, organismal fitness and increased risk of age-related diseases and death. Several hundred theories have attempted to explain this phenomenon. One of the most popular is the 'oxidative stress theory', originally termed the 'free radical theory'. The endocrine system seems to have a role in the modulation of oxidative stress; however, much less is known about the role that oxidative stress might have in the ageing of the endocrine system and the induction of age-related endocrine diseases. This Review outlines the interactions between hormones and oxidative metabolism and the potential effects of oxidative stress on ageing of endocrine organs. Many different mechanisms that link oxidative stress and ageing are discussed, all of which converge on the induction or regulation of inflammation. All these mechanisms, including cell senescence, mitochondrial dysfunction and microRNA dysregulation, as well as inflammation itself, could be targets of future studies aimed at clarifying the effects of oxidative stress on ageing of endocrine glands.

  9. Electrochemical impedance spectroscopy of oxidized porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Mula, Guido, E-mail: guido.mula@unica.it [Dipartimento di Fisica, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Cagliari (Italy); Tiddia, Maria V. [Dipartimento di Fisica, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Cagliari (Italy); Ruffilli, Roberta [Nanochemistry, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova (Italy); Falqui, Andrea [Nanochemistry, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova (Italy); Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Cagliari (Italy); Palmas, Simonetta; Mascia, Michele [Dipartimento di Ingegneria Meccanica Chimica e dei Materiali, Università degli Studi di Cagliari, Piazza d' Armi, 09126 Cagliari (Italy)

    2014-04-01

    We present a study of the electrochemical oxidation process of porous silicon. We analyze the effect of the layer thickness (1.25–22 μm) and of the applied current density (1.1–11.1 mA/cm{sup 2}, values calculated with reference to the external samples surface) on the oxidation process by comparing the galvanostatic electrochemical impedance spectroscopy (EIS) measurements and the optical specular reflectivity of the samples. The results of EIS were interpreted using an equivalent circuit to separate the contribution of different sample parts. A different behavior of the electrochemical oxidation process has been found for thin and thick samples: whereas for thin samples the oxidation process is univocally related to current density and thickness, for thicker samples this is no more true. Measurements by Energy Dispersive Spectroscopy using a Scanning Electron Microscopy confirmed that the inhomogeneity of the electrochemical oxidation process is increased by higher thicknesses and higher currents. A possible explanation is proposed to justify the different behavior of thin and thick samples during the electrochemical process. - Highlights: • A multidisciplinary approach on porous Si electrochemical oxidation is proposed. • Electrochemical, optical, and structural characterizations are used. • Layer thickness and oxidation current effects are shown. • An explanation of the observed behavior is proposed.

  10. Oxidative Stress and Antioxidant System in Periodontitis

    Science.gov (United States)

    Wang, Yue; Andrukhov, Oleh; Rausch-Fan, Xiaohui

    2017-01-01

    Periodontitis is a common inflammatory disease, which is initiated by bacterial infection and subsequently progressed by aberrant host response. It can result in the destruction of teeth supporting tissues and have an influence on systemic health. When periodontitis occurs, reactive oxygen species, which are overproduced mostly by hyperactive neutrophils, could not be balanced by antioxidant defense system and cause tissues damage. This is characterized by increased metabolites of lipid peroxidation, DNA damage and protein damage. Local and systemic activities of antioxidants can also be influenced by periodontitis. Total antioxidant capacity, total oxidant status and oxidative stress index have been used to evaluate the oxidative stress associated with periodontitis. Studies have confirmed that inflammatory response in periodontitis is associated with an increased local and systemic oxidative stress and compromised antioxidant capacity. Our review focuses on increased oxidative stress in periodontal disease, specifically, on the relationship between the local and systemic biomarkers of oxidative stress and periodontitis and their association with the pathogenesis of periodontitis. Also, the relationship between periodontitis and systemic inflammation, and the effects of periodontal therapy on oxidative stress parameters will be discussed. PMID:29180965

  11. Interferon-¿ regulates oxidative stress during experimental autoimmune encephalomyelitis

    DEFF Research Database (Denmark)

    Espejo, C.; Penkowa, Milena; Saez-Torres, I.

    2002-01-01

    Neurobiology, experimental autoimmune encephalomyelitis IFN-d, multiple sclerosis, neurodegeneration, oxidative stress......Neurobiology, experimental autoimmune encephalomyelitis IFN-d, multiple sclerosis, neurodegeneration, oxidative stress...

  12. High surface area, electrically conductive nanocarbon-supported metal oxide

    Energy Technology Data Exchange (ETDEWEB)

    Worsley, Marcus A.; Han, Thomas Yong-Jin; Kuntz, Joshua D.; Cervantes, Octavio; Gash, Alexander E.; Baumann, Theodore F.; Satcher, Jr., Joe H.

    2015-07-14

    A metal oxide-carbon composite includes a carbon aerogel with an oxide overcoat. The metal oxide-carbon composite is made by providing a carbon aerogel, immersing the carbon aerogel in a metal oxide sol under a vacuum, raising the carbon aerogel with the metal oxide sol to atmospheric pressure, curing the carbon aerogel with the metal oxide sol at room temperature, and drying the carbon aerogel with the metal oxide sol to produce the metal oxide-carbon composite. The step of providing a carbon aerogel can provide an activated carbon aerogel or provide a carbon aerogel with carbon nanotubes that make the carbon aerogel mechanically robust.

  13. Nanocrystalline cerium oxide materials for solid fuel cell systems

    Science.gov (United States)

    Brinkman, Kyle S

    2015-05-05

    Disclosed are solid fuel cells, including solid oxide fuel cells and PEM fuel cells that include nanocrystalline cerium oxide materials as a component of the fuel cells. A solid oxide fuel cell can include nanocrystalline cerium oxide as a cathode component and microcrystalline cerium oxide as an electrolyte component, which can prevent mechanical failure and interdiffusion common in other fuel cells. A solid oxide fuel cell can also include nanocrystalline cerium oxide in the anode. A PEM fuel cell can include cerium oxide as a catalyst support in the cathode and optionally also in the anode.

  14. Oxidative Stress Resistance in Deinococcus radiodurans†

    Science.gov (United States)

    Slade, Dea; Radman, Miroslav

    2011-01-01

    Summary: Deinococcus radiodurans is a robust bacterium best known for its capacity to repair massive DNA damage efficiently and accurately. It is extremely resistant to many DNA-damaging agents, including ionizing radiation and UV radiation (100 to 295 nm), desiccation, and mitomycin C, which induce oxidative damage not only to DNA but also to all cellular macromolecules via the production of reactive oxygen species. The extreme resilience of D. radiodurans to oxidative stress is imparted synergistically by an efficient protection of proteins against oxidative stress and an efficient DNA repair mechanism, enhanced by functional redundancies in both systems. D. radiodurans assets for the prevention of and recovery from oxidative stress are extensively reviewed here. Radiation- and desiccation-resistant bacteria such as D. radiodurans have substantially lower protein oxidation levels than do sensitive bacteria but have similar yields of DNA double-strand breaks. These findings challenge the concept of DNA as the primary target of radiation toxicity while advancing protein damage, and the protection of proteins against oxidative damage, as a new paradigm of radiation toxicity and survival. The protection of DNA repair and other proteins against oxidative damage is imparted by enzymatic and nonenzymatic antioxidant defense systems dominated by divalent manganese complexes. Given that oxidative stress caused by the accumulation of reactive oxygen species is associated with aging and cancer, a comprehensive outlook on D. radiodurans strategies of combating oxidative stress may open new avenues for antiaging and anticancer treatments. The study of the antioxidation protection in D. radiodurans is therefore of considerable potential interest for medicine and public health. PMID:21372322

  15. Oxidative stress resistance in Deinococcus radiodurans.

    Science.gov (United States)

    Slade, Dea; Radman, Miroslav

    2011-03-01

    Deinococcus radiodurans is a robust bacterium best known for its capacity to repair massive DNA damage efficiently and accurately. It is extremely resistant to many DNA-damaging agents, including ionizing radiation and UV radiation (100 to 295 nm), desiccation, and mitomycin C, which induce oxidative damage not only to DNA but also to all cellular macromolecules via the production of reactive oxygen species. The extreme resilience of D. radiodurans to oxidative stress is imparted synergistically by an efficient protection of proteins against oxidative stress and an efficient DNA repair mechanism, enhanced by functional redundancies in both systems. D. radiodurans assets for the prevention of and recovery from oxidative stress are extensively reviewed here. Radiation- and desiccation-resistant bacteria such as D. radiodurans have substantially lower protein oxidation levels than do sensitive bacteria but have similar yields of DNA double-strand breaks. These findings challenge the concept of DNA as the primary target of radiation toxicity while advancing protein damage, and the protection of proteins against oxidative damage, as a new paradigm of radiation toxicity and survival. The protection of DNA repair and other proteins against oxidative damage is imparted by enzymatic and nonenzymatic antioxidant defense systems dominated by divalent manganese complexes. Given that oxidative stress caused by the accumulation of reactive oxygen species is associated with aging and cancer, a comprehensive outlook on D. radiodurans strategies of combating oxidative stress may open new avenues for antiaging and anticancer treatments. The study of the antioxidation protection in D. radiodurans is therefore of considerable potential interest for medicine and public health.

  16. Preparation of iron oxides and oxihydroxides

    Directory of Open Access Journals (Sweden)

    Iveta Štyriaková

    2006-12-01

    Full Text Available Iron oxides are common minerals that occur in the environment, either naturally or as a result of human activities.The most common Fe(III-hydroxides and -oxides include ferrihydrite (Fe5HO8 .4H2O that transforms to hematite (a-Fe2O3 and/or goethite (a-FeOOH.That depends on the solution composition, temperature and pH. Depending on the composition of the solid and solution, oxidation can transform the green rust (a product formed by a metal corrosion to lepidocrocite (γ -FeOOH or magnetite (Fe(IIFe(III 2O4 . Weathering can degrade magnetite to maghemite (γ –Fe2O3 and all of the Fe-oxides are subject to an attack and dissolution by organic acids and ligands that are formed during the breakdown of biological material. Iron oxides can be prepared by hydrolysis of acidic Fe3+ solutions or by controlled oxidation of Fe2+ solutions. Goethite, lepidocrocite and magnetite were prepared by oxidation of Fe2+ solutions under slightly different values of pH, Fe concentrations and rates of oxidation. Maghemite was prepared by a thermal transformation from synthetic lepidocrocite heated in a furnace at 250 °C for 2h. Hematite was prepared by forced hydrolysis of Fe3+ solution from a chlorine system (FeCl3 at the temperature close to 100 °C under strongly acidic conditions (pH 1-2. Main mineral phases were confirmed by the RTG diffraction and IR spectroscopy method. Iron oxides are excellent, renewable adsorbents, and often control free metals through adsorption reaction.

  17. Homogeneous and heterogenized iridium water oxidation catalysts

    Science.gov (United States)

    Macchioni, Alceo

    2014-10-01

    The development of an efficient catalyst for the oxidative splitting of water into molecular oxygen, protons and electrons is of key importance for producing solar fuels through artificial photosynthesis. We are facing the problem by means of a rational approach aimed at understanding how catalytic performance may be optimized by the knowledge of the reaction mechanism of water oxidation and the fate of the catalytic site under the inevitably harsh oxidative conditions. For the purposes of our study we selected iridium water oxidation catalysts, exhibiting remarkable performance (TOF > 5 s-1 and TON > 20000). In particular, we recently focused our attention on [Cp*Ir(N,O)X] (N,O = 2-pyridincarboxylate; X = Cl or NO3) and [IrCl(Hedta)]Na water oxidation catalysts. The former exhibited a remarkable TOF whereas the latter showed a very high TON. Furthermore, [IrCl(Hedta)]Na was heterogenized onto TiO2 taking advantage of the presence of a dandling -COOH functionality. The heterogenized catalyst maintained approximately the same catalytic activity of the homogeneous analogous with the advantage that could be reused many times. Mechanistic studies were performed in order to shed some light on the rate-determining step and the transformation of catalysts when exposed to "oxidative stress". It was found that the last oxidative step, preceding oxygen liberation, is the rate-determining step when a small excess of sacrificial oxidant is used. In addition, several intermediates of the oxidative transformation of the catalyst were intercepted and characterized by NMR, X-Ray diffractometry and ESI-MS.

  18. Star polymer unimicelles on graphene oxide flakes.

    Science.gov (United States)

    Choi, Ikjun; Kulkarni, Dhaval D; Xu, Weinan; Tsitsilianis, Constantinos; Tsukruk, Vladimir V

    2013-08-06

    We report the interfacial assembly of amphiphilic heteroarm star copolymers (PSnP2VPn and PSn(P2VP-b-PtBA)n (n = 28 arms)) on graphene oxide flakes at the air-water interface. Adsorption, spreading, and ordering of star polymer micelles on the surface of the basal plane and edge of monolayer graphene oxide sheets were investigated on a Langmuir trough. This interface-mediated assembly resulted in micelle-decorated graphene oxide sheets with uniform spacing and organized morphology. We found that the surface activity of solvated graphene oxide sheets enables star polymer surfactants to subsequently adsorb on the presuspended graphene oxide sheets, thereby producing a bilayer complex. The positively charged heterocyclic pyridine-containing star polymers exhibited strong affinity onto the basal plane and edge of graphene oxide, leading to a well-organized and long-range ordered discrete micelle assembly. The preferred binding can be related to the increased conformational entropy due to the reduction of interarm repulsion. The extent of coverage was tuned by controlling assembly parameters such as concentration and solvent polarity. The polymer micelles on the basal plane remained incompressible under lateral compression in contrast to ones on the water surface due to strongly repulsive confined arms on the polar surface of graphene oxide and a preventive barrier in the form of the sheet edges. The densely packed biphasic tile-like morphology was evident, suggesting the high interfacial stability and mechanically stiff nature of graphene oxide sheets decorated with star polymer micelles. This noncovalent assembly represents a facile route for the control and fabrication of graphene oxide-inclusive ultrathin hybrid films applicable for layered nanocomposites.

  19. Influence of oxidation temperature on the oxide scale formation of NiCoCrAl coatings

    Science.gov (United States)

    Sugiarti, E.; Zaini, K. A.; Sundawa, R.; Wang, Y.; Ohnuki, S.; Hayashi, S.

    2017-04-01

    Intermetalic coatings of NiCoCrAl have been successfully developed on low carbon steel substrate to improve oxidation resistance in extreme environments. The influence of oxidation temperature on the oxide scale formation was studied in the temperature range of 600-1000 °C. The measurements were made in air under isothermal oxidation test for 100 h. The surface morphology showed that a cauliflower like structure developed entire the oxide scale of sample oxidized at 800 °C and 1000 °C, while partly distributed on the surface of sample oxidized at 600 °C. The XRD analysis identified Cr2O3 phase predominantly formed on the oxidized sample at 600 °C and meta-stable Al2O3 with several polymorphs crystalline structures: η, δ, θ, κ, and α-Al2O3 at relatively high temperatures, i.e. 800 °C and 1000 °C. A Cross-sectional microstructure showed that complex and porous structures formed on the top surface of 600 °C and 1000 °C samples. In contrast, a very thin oxide scale formed on 800 °C oxidized samples and it appeared to act as a diffusion barrier of oxygen to diffuse inward, hence could increase in the service life of carbon steel substrate.

  20. Global DNA methylation and oxidative stress biomarkers in workers exposed to metal oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Liou, Saou-Hsing; Wu, Wei-Te; Liao, Hui-Yi [National Institute of Environmental Health Sciences, National Health Research Institutes, Zhunan, Miaoli County, Taiwan (China); Chen, Chao-Yu; Tsai, Cheng-Yen; Jung, Wei-Ting [Department of Chemistry, Fu Jen Catholic University, New Taipei City, Taiwan (China); Lee, Hui-Ling, E-mail: huilinglee3573@gmail.com [Department of Chemistry, Fu Jen Catholic University, New Taipei City, Taiwan (China)

    2017-06-05

    Highlights: • Global methylation and oxidative DNA damage levels in nanomaterial handling workers were assessed. • 8-isoprostane in exhaled breath condensate of workers exposed to nanoparticles was higher. • 8-OHdG was negatively correlated with global methylation. • Exposure to metal oxide nanoparticles may lead to global methylation and DNA oxidative damage. - Abstract: This is the first study to assess global methylation, oxidative DNA damage, and lipid peroxidation in workers with occupational exposure to metal oxide nanomaterials (NMs). Urinary and white blood cell (WBC) 8-hydroxydeoxyguanosine (8-OHdG), and exhaled breath condensate (EBC) 8-isoprostane were measured as oxidative stress biomarkers. WBC global methylation was measured as an epigenetic alteration. Exposure to TiO{sub 2}, SiO{sub 2,} and indium tin oxide (ITO) resulted in significantly higher oxidative biomarkers such as urinary 8-OHdG and EBC 8-isoprostane. However, significantly higher WBC 8-OHdG and lower global methylation were only observed in ITO handling workers. Significant positive correlations were noted between WBC and urinary 8-OHdG (Spearman correlation r = 0.256, p = 0.003). Furthermore, a significant negative correlation was found between WBC 8-OHdG and global methylation (r = −0.272, p = 0.002). These results suggest that exposure to metal oxide NMs may lead to global methylation, DNA oxidative damage, and lipid peroxidation.