WorldWideScience

Sample records for subcluster oxidation states

  1. Common Subcluster Mining in Microarray Data for Molecular Biomarker Discovery.

    Science.gov (United States)

    Sadhu, Arnab; Bhattacharyya, Balaram

    2017-10-11

    Molecular biomarkers can be potential facilitators for detection of cancer at early stage which is otherwise difficult through conventional biomarkers. Gene expression data from microarray experiments on both normal and diseased cell samples provide enormous scope to explore genetic relations of disease using computational techniques. Varied patterns of expressions of thousands of genes at different cell conditions along with inherent experimental error make the task of isolating disease related genes challenging. In this paper, we present a data mining method, common subcluster mining (CSM), to discover highly perturbed genes under diseased condition from differential expression patterns. The method builds heap through superposing near centroid clusters from gene expression data of normal samples and extracts its core part. It, thus, isolates genes exhibiting the most stable state across normal samples and constitute a reference set for each centroid. It performs the same operation on datasets from corresponding diseased samples and isolates the genes showing drastic changes in their expression patterns. The method thus finds the disease-sensitive genesets when applied to datasets of lung cancer, prostrate cancer, pancreatic cancer, breast cancer, leukemia and pulmonary arterial hypertension. In majority of the cases, few new genes are found over and above some previously reported ones. Genes with distinct deviations in diseased samples are prospective candidates for molecular biomarkers of the respective disease.

  2. Genome Sequences of Four Subcluster L2 Mycobacterium Phages, Finemlucis, Miley16, Wilder, and Zakai

    OpenAIRE

    Herren, Christopher D.; Peister, Alexandra; Breton, Timothy S.; Hill, Maggie S.; Anderson, Marcy S.; Chang, Adeline W.; Klein, Sydney B.; Thornton, Mackenzie M.; Vars, Stacy J.; Wagner, Kasey E.; Wiebe, Paige L.; Williams, Thomas G.; Yanez, Coraima P.; Ackles, Jasanta M.; Artis, Darius

    2017-01-01

    ABSTRACT Four subcluster L2 mycobacteriophages, Finemlucis, Miley16, Wilder, and Zakai, that infect Mycobacterium smegmatis mc2155 were isolated. The four phages are closely related to each other and code for 12 to 14 tRNAs and 130 to 132 putative protein-coding genes, including tyrosine integrases, cro, immunity repressors, and excise genes involved in the establishment of lysogeny.

  3. Genome Sequences of Subcluster K5 Mycobacteriophages AlleyCat, Edugator, and Guillsminger.

    Science.gov (United States)

    King, Rodney A; Slowan-Pomeroy, Tina M; Thomas, Jodi E; Ahmed, Tithe; Alexander, Katie L; Biddle, James M; Daniels, Makenzie K; Rowlett, Jenna R; Senay, Taylor E; Rinehart, Claire A; Staples, Amanda K; Rowland, Naomi S; Gaffney, Bobby L; Emmons, Christine B; Hauk, Maya D; Nguyen, Rebecca L; Naegele, Leonard; Strickland, Summer S; Briggs, Laura A; Rush, Alexander N; Saha, Sanghamitra; Sadana, Rachna; Cresawn, Steven G; Russell, Daniel A; Garlena, Rebecca A; Pope, Welkin H; Jacobs-Sera, Deborah; Hatfull, Graham F

    2017-11-09

    Bacteriophages AlleyCat, Edugator, and Guillsminger were isolated on Mycobacterium smegmatis mc 2 155 from enriched soil samples. All are members of mycobacteriophage subcluster K5, with genomes of 62,112 to 63,344 bp. Each genome contains 92 to 99 predicted protein-coding genes and one tRNA. Guillsminger is the first mycobacteriophage to carry an IS 1380 family transposon. Copyright © 2017 King et al.

  4. Surveillance technology for HIV-1 subtype C in Ethiopia: an env-based NASBA molecular beacon assay to discriminate between subcluster C and C'

    NARCIS (Netherlands)

    Ayele, Workenesh; Baar, Michel P. de; Goudsmit, Jaap; Kliphuis, Aletta; Tilahun, Tesfaye; Dorigo-Zetsma, Wendelien; Wolday, Dawit; Abebe, Almaz; Mengistu, Yohannes; Pollakis, Georgios

    2005-01-01

    Forty-nine samples with known C2V3 sequences were used for the evaluation of an env-based molecular beacon assay to distinguish between the two genetic subclusters C and C' which characterize the HIV-1 epidemic in Ethiopia. Two subcluster C and two subcluster C' beacons targeting two different loci

  5. Industrial & Engineering Systems Career Cluster ITAC for Career-Focused Education: Transportation Sub-Cluster. Integrated Technical & Academic Competencies.

    Science.gov (United States)

    Ohio State Univ., Columbus. Vocational Instructional Materials Lab.

    Designed for Ohio educators responsible for planning programs to prepare high school students for careers in transportation, this document presents an overview of Ohio's Integrated Technical and Academic Competencies (ITAC) system of career-focused education and specific information about the transportation subcluster of the industrial and…

  6. Oxidation-state maxima in plutonium chemistry

    International Nuclear Information System (INIS)

    Silver, G.L.

    2013-01-01

    Maxima in the fractions of the trivalent and hexavalent oxidation states of plutonium are inherent in the algebra of its disproportionation reactions. The maxima do not support overall disproportionation equations as satisfactory representations of aqueous plutonium. (author)

  7. Sample selection based on kernel-subclustering for the signal reconstruction of multifunctional sensors

    International Nuclear Information System (INIS)

    Wang, Xin; Wei, Guo; Sun, Jinwei

    2013-01-01

    The signal reconstruction methods based on inverse modeling for the signal reconstruction of multifunctional sensors have been widely studied in recent years. To improve the accuracy, the reconstruction methods have become more and more complicated because of the increase in the model parameters and sample points. However, there is another factor that affects the reconstruction accuracy, the position of the sample points, which has not been studied. A reasonable selection of the sample points could improve the signal reconstruction quality in at least two ways: improved accuracy with the same number of sample points or the same accuracy obtained with a smaller number of sample points. Both ways are valuable for improving the accuracy and decreasing the workload, especially for large batches of multifunctional sensors. In this paper, we propose a sample selection method based on kernel-subclustering distill groupings of the sample data and produce the representation of the data set for inverse modeling. The method calculates the distance between two data points based on the kernel-induced distance instead of the conventional distance. The kernel function is a generalization of the distance metric by mapping the data that are non-separable in the original space into homogeneous groups in the high-dimensional space. The method obtained the best results compared with the other three methods in the simulation. (paper)

  8. Dynamical evolution of stars and gas of young embedded stellar sub-clusters

    Science.gov (United States)

    Sills, Alison; Rieder, Steven; Scora, Jennifer; McCloskey, Jessica; Jaffa, Sarah

    2018-03-01

    We present simulations of the dynamical evolution of young embedded star clusters. Our initial conditions are directly derived from X-ray, infrared, and radio observations of local systems, and our models evolve both gas and stars simultaneously. Our regions begin with both clustered and extended distributions of stars, and a gas distribution which can include a filamentary structure in addition to gas surrounding the stellar subclusters. We find that the regions become spherical, monolithic, and smooth quite quickly, and that the dynamical evolution is dominated by the gravitational interactions between the stars. In the absence of stellar feedback, the gas moves gently out of the centre of our regions but does not have a significant impact on the motions of the stars at the earliest stages of cluster formation. Our models at later times are consistent with observations of similar regions in the local neighbourhood. We conclude that the evolution of young proto-star clusters is relatively insensitive to reasonable choices of initial conditions. Models with more realism, such as an initial population of binary and multiple stars and ongoing star formation, are the next step needed to confirm these findings.

  9. Thermodynamic Ground States of Complex Oxide Heterointerfaces

    DEFF Research Database (Denmark)

    Gunkel, F.; Hoffmann-Eifert, S.; Heinen, R. A.

    2017-01-01

    The formation mechanism of 2-dimensional electron gases (2DEGs) at heterointerfaces between nominally insulating oxides is addressed with a thermodynamical approach. We provide a comprehensive analysis of the thermodynamic ground states of various 2DEG systems directly probed in high temperature...

  10. Higher Americium Oxidation State Research Roadmap

    Energy Technology Data Exchange (ETDEWEB)

    Mincher, Bruce J. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Law, Jack D. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Goff, George S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Moyer, Bruce A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Burns, Jon D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lumetta, Gregg J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Sinkov, Sergey I. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Shehee, Thomas C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hobbs, David T. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-12-18

    The partitioning of hexavalent Am from dissolved nuclear fuel requires the ability to efficiently oxidize Am(III) to Am(VI) and to maintain that oxidation state for a length of time sufficient to perform the separation. Several oxidants have been, or are being developed. Chemical oxidants include Ag-catalyzed ozone, Ag-catalyzed peroxydisulfate, Cu(III) periodate, and sodium bismuthate. Hexavalent americium has also now successfully been prepared by electrolysis, using functionalized electrodes. So-called auto-reduction rates of Am(VI) are sufficiently slow to allow for separations. However, for separations based on solvent extraction or ion exchange using organic resins, the high valence state must be maintained under the reducing conditions of the organic phase contact, and a holding oxidant is probably necessary. Until now, only Cu(III) periodate and sodium bismuthate oxidation have been successfully combined with solvent extraction separations. Bismuthate oxidation provided the higher DAm, since it acts as its own holding oxidant, and a successful hot test using centrifugal contactors was performed. For the other oxidants, Ag-catalyzed peroxydisulfate will not oxidize americium in nitric acid concentrations above 0.3 M, and it is not being further investigated. Peroxydisulfate in the absence of Ag catalysis is being used to prepare Am(V) in ion exchange work, discussed below. Preliminary work with Ag-catalyzed ozone has been unsuccessful for extractions of Am(VI) from 6.5 M HNO3, and only one attempt at extraction, also from 6.5 M HNO3, using the electrolytic oxidation has been attempted. However, this high acid concentration was based on the highest Am extraction efficiency using the bismuthate oxidant; which is only sparingly soluble, and thus the oxidation yield is based on bismuthate solubility. Lower acid concentrations may be sufficient with alternative oxidants and work with Ag-ozone, Cu(III) and electrolysis is on-going. Two non

  11. Social and attention-to-detail subclusters of autistic traits differentially predict looking at eyes and face identity recognition ability.

    Science.gov (United States)

    Davis, Joshua; McKone, Elinor; Zirnsak, Marc; Moore, Tirin; O'Kearney, Richard; Apthorp, Deborah; Palermo, Romina

    2017-02-01

    This study distinguished between different subclusters of autistic traits in the general population and examined the relationships between these subclusters, looking at the eyes of faces, and the ability to recognize facial identity. Using the Autism Spectrum Quotient (AQ) measure in a university-recruited sample, we separate the social aspects of autistic traits (i.e., those related to communication and social interaction; AQ-Social) from the non-social aspects, particularly attention-to-detail (AQ-Attention). We provide the first evidence that these social and non-social aspects are associated differentially with looking at eyes: While AQ-Social showed the commonly assumed tendency towards reduced looking at eyes, AQ-Attention was associated with increased looking at eyes. We also report that higher attention-to-detail (AQ-Attention) was then indirectly related to improved face recognition, mediated by increased number of fixations to the eyes during face learning. Higher levels of socially relevant autistic traits (AQ-Social) trended in the opposite direction towards being related to poorer face recognition (significantly so in females on the Cambridge Face Memory Test). There was no evidence of any mediated relationship between AQ-Social and face recognition via reduced looking at the eyes. These different effects of AQ-Attention and AQ-Social suggest face-processing studies in Autism Spectrum Disorder might similarly benefit from considering symptom subclusters. Additionally, concerning mechanisms of face recognition, our results support the view that more looking at eyes predicts better face memory. © 2016 The British Psychological Society.

  12. Photochemical oxidants: state of the science.

    Science.gov (United States)

    Kley, D; Kleinmann, M; Sanderman, H; Krupa, S

    1999-01-01

    Atmospheric photochemical processes resulting in the production of tropospheric ozone (O(3)) and other oxidants are described. The spatial and temporal variabilities in the occurrence of surface level oxidants and their relationships to air pollution meteorology are discussed. Models of photooxidant formation are reviewed in the context of control strategies and comparisons are provided of the air concentrations of O(3) at select geographic locations around the world. This overall oxidant (O(3)) climatology is coupled to human health and ecological effects. The discussion of the effects includes both acute and chronic responses, mechanisms of action, human epidemiological and plant population studies and briefly, efforts to establish cause-effect relationships through numerical modeling. A short synopsis is provided of the interactive effects of O(3) with other abiotic and biotic factors. The overall emphasis of the paper is on identifying the current uncertainties and gaps in our understanding of the state of the science and some suggestions as to how they may be addressed.

  13. Plutonium disproportionation. Hydrolysis and local oxidation-state maxima

    International Nuclear Information System (INIS)

    Silver, G.L.

    2014-01-01

    Local maxima in the fractions of the trivalent and hexavalent oxidation states are inherent in the algebra of Pu disproportionation reactions. A new method predicts the pH and the oxidation-state fractions at maximum. Tabulated results illustrate the effects of the Pu oxidation number and Pu(IV) hydrolysis on the maxima. This method suggests a new laboratory approach for discovering Pu oxidation-state maxima. (author)

  14. High-density fecal Enterococcus faecium colonization in hospitalized patients is associated with the presence of the polyclonal subcluster CC17

    NARCIS (Netherlands)

    Ruiz-Garbajosa, P.; de Regt, M.; Bonten, M.; Baquero, F.; Coque, T. M.; Canton, R.; Harmsen, H. J. M.; Willems, Rob J. L.

    Enterococcus faecium belonging to the polyclonal subcluster CC17, with a typical ampicillin-resistant E. faecium (AREfm) phenotype, have become prevalent among nosocomial infections around the world. High-density intestinal AREfm colonization could be one of the factors contributing to the

  15. 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.

  16. Non-equilibrium oxidation states of zirconium during early stages of metal oxidation

    International Nuclear Information System (INIS)

    Ma, Wen; Yildiz, Bilge; Herbert, F. William; Senanayake, Sanjaya D.

    2015-01-01

    The chemical state of Zr during the initial, self-limiting stage of oxidation on single crystal zirconium (0001), with oxide thickness on the order of 1 nm, was probed by synchrotron x-ray photoelectron spectroscopy. Quantitative analysis of the Zr 3d spectrum by the spectrum reconstruction method demonstrated the formation of Zr 1+ , Zr 2+ , and Zr 3+ as non-equilibrium oxidation states, in addition to Zr 4+ in the stoichiometric ZrO 2 . This finding resolves the long-debated question of whether it is possible to form any valence states between Zr 0 and Zr 4+ at the metal-oxide interface. The presence of local strong electric fields and the minimization of interfacial energy are assessed and demonstrated as mechanisms that can drive the formation of these non-equilibrium valence states of Zr

  17. Oxidatively generated DNA/RNA damage in psychological stress states

    DEFF Research Database (Denmark)

    Jørgensen, Anders

    2013-01-01

    age-related somatic disorders. The overall aim of the PhD project was to investigate the relation between psychopathology, psychological stress, stress hormone secretion and oxidatively generated DNA and RNA damage, as measured by the urinary excretion of markers of whole-body DNA/RNA oxidation (8...... between the 24 h urinary cortisol excretion and the excretion of 8-oxodG/8-oxoGuo, determined in the same samples. Collectively, the studies could not confirm an association between psychological stress and oxidative stress on nucleic acids. Systemic oxidatively generated DNA/RNA damage was increased......Both non-pathological psychological stress states and mental disorders are associated with molecular, cellular and epidemiological signs of accelerated aging. Oxidative stress on nucleic acids is a critical component of cellular and organismal aging, and a suggested pathogenic mechanism in several...

  18. Charge state of oxide layer of SIMOX-structures

    CERN Document Server

    Askinazi, A Y; Dmitriev, V A; Miloglyadova, L V

    2001-01-01

    The charge state of the oxide layer of the SIMOX-structures, obtained in the course of forming the oxide layers, bricked up in the silicon volume, through the oxygen ions implantation into the Si, is studied. The charge state of the given structures is studied through the method of the layer-by-layer profiling, which makes it possible to obtain the dependence of the plane zones potential on the oxide layer thickness. It is established, that during the process of the SIMOX-structures formation in the oxide layer near the boundary with the Si there appear defects, responsible for the charge. The radiation from the near-the-ultraviolet (NUV) area without the applied electric field neutralizes the given charge. The simultaneous impact of the NUV-radiation and electric field leads to the formation of significantly positive charge

  19. Effect of microorganisms on the plutonium oxidation states

    International Nuclear Information System (INIS)

    Lukšienė, Benedikta; Druteikienė, Rūta; Pečiulytė, Dalia; Baltrūnas, Dalis; Remeikis, Vidmantas; Paškevičius, Algimantas

    2012-01-01

    Particular microbes from substrates at the low-level radioactive waste repository in the Ignalina NPP territory were exposed to 239 Pu (IV) at low pH under aerobic conditions. Pu(III) and Pu(IV) were separated and quantitatively evaluated using the modified anion exchange method and alpha spectrometry. Tested bacteria Bacillus mycoides and Serratia marcescens were more effective in Pu reduction than Rhodococcus fascians. Fungi Paecillomyces lilacinus and Absidia spinosa var. spinosa as well as bacterium Rhodococcus fascians did not alter the plutonium oxidation state. - Highlights: ► Particular microbes from low-level radioactive waste repository were exposed to Pu (IV). ► Some tested bacteria induced slight Pu (IV) reduction at low pH under aerobic conditions. ► Tested fungi did not show peculiarities to alter Pu oxidation state. ► The modified radiochemical method was applied to differentiate Pu oxidation states.

  20. Effect of microorganisms on the plutonium oxidation states

    Energy Technology Data Exchange (ETDEWEB)

    Luksiene, Benedikta, E-mail: bena@ar.fi.lt [Center for Physical Sciences and Technology, Savanoriu ave 231, LT-02300 Vilnius (Lithuania); Druteikiene, Ruta [Center for Physical Sciences and Technology, Savanoriu ave 231, LT-02300 Vilnius (Lithuania); Peciulyte, Dalia [Nature Research Centre, Akademijos street 2, LT-08412 Vilnius (Lithuania); Baltrunas, Dalis; Remeikis, Vidmantas [Center for Physical Sciences and Technology, Savanoriu ave 231, LT-02300 Vilnius (Lithuania); Paskevicius, Algimantas [Nature Research Centre, Akademijos street 2, LT-08412 Vilnius (Lithuania)

    2012-03-15

    Particular microbes from substrates at the low-level radioactive waste repository in the Ignalina NPP territory were exposed to {sup 239}Pu (IV) at low pH under aerobic conditions. Pu(III) and Pu(IV) were separated and quantitatively evaluated using the modified anion exchange method and alpha spectrometry. Tested bacteria Bacillus mycoides and Serratia marcescens were more effective in Pu reduction than Rhodococcus fascians. Fungi Paecillomyces lilacinus and Absidia spinosa var. spinosa as well as bacterium Rhodococcus fascians did not alter the plutonium oxidation state. - Highlights: Black-Right-Pointing-Pointer Particular microbes from low-level radioactive waste repository were exposed to Pu (IV). Black-Right-Pointing-Pointer Some tested bacteria induced slight Pu (IV) reduction at low pH under aerobic conditions. Black-Right-Pointing-Pointer Tested fungi did not show peculiarities to alter Pu oxidation state. Black-Right-Pointing-Pointer The modified radiochemical method was applied to differentiate Pu oxidation states.

  1. Shifts in oxidation states of cerium oxide nanoparticles detected inside intact hydrated cells and organelles

    Energy Technology Data Exchange (ETDEWEB)

    Szymanski, Craig J.; Munusamy, Prabhakaran; Mihai, Cosmin; Xie, Yumei; Hu, Dehong; Gilles, Marry K.; Tyliszczak, T.; Thevuthasan, Suntharampillai; Baer, Donald R.; Orr, Galya

    2015-09-01

    Cerium oxide nanoparticles (CNPs) have been shown to induce diverse biological effects, ranging from toxic to beneficial. The beneficial effects have been attributed to the potential antioxidant activity of CNPs via certain redox reactions, depending on their oxidation state or Ce3+/Ce4+ ratio. However, this ratio is strongly dependent on the environment and age of the nanoparticles and it is unclear whether and how the complex intracellular environment impacts this ratio and the possible redox reactions of CNPs. To identify any changes in the oxidation state of CNPs in the intracellular environment and better understand their intracellular reactions, we directly quantified the oxidation states of CNPs outside and inside intact hydrated cells and organelles using correlated scanning transmission x-ray and super resolution fluorescence microscopies. By analyzing hundreds of small CNP aggregates, we detected a shift to a higher Ce3+/Ce4+ ratio in CNPs inside versus outside the cells, indicating a net reduction of CNPs in the intracellular environment. We further found a similar ratio in the cytoplasm and in the lysosomes, indicating that the net reduction occurs earlier in the internalization pathway. Together with oxidative stress and toxicity measurements, our observations identify a net reduction of CNPs in the intracellular environment, which is consistent with their involvement in potentially beneficial oxidation reactions, but also point to interactions that can negatively impact the health of cells.

  2. Relationships among oxidation-reduction and acid-base properties of the actinides in high oxidation states

    International Nuclear Information System (INIS)

    Morss, L.R.

    1992-01-01

    The first chemical identification of plutonium, its subsequent isolation on the macroscopic scale, and more recent chemical separation schemes were achieved by taking advantage of the differences among the oxidation states of uranium, neptunium, and plutonium. Many acid-base properties modify the relative stabilities of oxidation states of the actinides. In the solid state, strongly basic compounds such as Cs 2 O yield complex oxides with oxidation states of Np(VII), Pu(VI), and Am(VI) whereas more acidic compounds such as CsF yield complex fluorides with lower oxidation states. In aqueous solution, high basicity and strongly covalent complexes favor high oxidation states. In nonaqueous solvent systems, high acidity generally favors low oxidation states. This paper elucidates and attempts to interpret the effects of these acid-base properties in a systematic fashion

  3. Oxidative Stress and Heart Failure in Altered Thyroid States

    Directory of Open Access Journals (Sweden)

    Pallavi Mishra

    2012-01-01

    Full Text Available Increased or reduced action of thyroid hormone on certain molecular pathways in the heart and vasculature causes relevant cardiovascular derangements. It is well established that hyperthyroidism induces a hyperdynamic cardiovascular state, which is associated with a faster heart rate, enhanced left ventricular systolic and diastolic function whereas hypothyroidism is characterized by the opposite changes. Hyperthyroidism and hypothyroidism represent opposite clinical conditions, albeit not mirror images. Recent experimental and clinical studies have suggested the involvement of ROS tissue damage under altered thyroid status. Altered-thyroid state-linked changes in heart modify their susceptibility to oxidants and the extent of the oxidative damage they suffer following oxidative challenge. Chronic increase in the cellular levels of ROS can lead to a catastrophic cycle of DNA damage, mitochondrial dysfunction, further ROS generation and cellular injury. Thus, these cellular events might play an important role in the development and progression of myocardial remodeling and heart failure in altered thyroid states (hypo- and hyper-thyroidism. The present review aims at elucidating the various signaling pathways mediated via ROS and their modulation under altered thyroid state and the possibility of antioxidant therapy.

  4. Evolution of the Oxidation State of the Earth's Mantle

    Science.gov (United States)

    Danielson, L. R.; Righter, K.; Keller, L.; Christoffersen, E.; Rahman, Z.

    2015-01-01

    The oxidation state of the Earth's mantle during formation remains an unresolved question, whether it was constant throughout planetary accretion, transitioned from reduced to oxidized, or from oxidized to reduced. We investigate the stability of Fe3(+) at depth, in order to constrain processes (water, late accretion, dissociation of FeO) which may reduce or oxidize the Earth's mantle. In our previous experiments on shergottite compositions, variable fO2, T, and P less than 4 GPa, Fe3(+)/sigma Fe decreased slightly with increasing P, similar to terrestrial basalt. For oxidizing experiments less than 7GPa, Fe3(+)/sigma Fe decreased as well, but it's unclear from previous modelling whether the deeper mantle could retain significant Fe3(+). Our current experiments expand our pressure range deeper into the Earth's mantle and focus on compositions and conditions relevant to the early Earth. Preliminary multi-anvil experiments with Knippa basalt as the starting composition were conducted at 5-7 GPa and 1800 C, using a molybdenum capsule to set the fO2 near IW, by buffering with Mo-MoO3. TEM and EELS analyses revealed the run products quenched to polycrystalline phases, with the major phase pyroxene containing approximately equal to Fe3(+)/2(+). Experiments are underway to produce glassy samples that can be measured by EELS and XANES, and are conducted at higher pressures.

  5. Corrosion-product transport, oxidation state and remedial measures

    International Nuclear Information System (INIS)

    Sawicki, J.A.; Brett, M.E.; Tapping, R.L.

    1998-10-01

    The issues associated with monitoring and controlling corrosion-product transport (CPT) in the balance-of-plant (BOP) and steam generators (SG) of CANDU stations are briefly reviewed. Efforts are focused on minimizing corrosion of carbon steel, which is used extensively in the CANDU primary and secondary systems. Emphasis is placed on the corrosion-product oxidation state as a monitor of water chemistry effectiveness and as a monitor of system corrosion effects. The discussion is based mostly on the results of observations from Ontario Hydro plants, and their comparisons with pressurized-water reactors. The effects of low oxygen and elevated hydrazine chemistry are reviewed, as well as the effects of layup and various startup conditions. Progress in monitoring electrochemical potential (ECP) at Ontario Hydro plants and its relationship to the oxidation state of corrosion products is reviewed. Observations on CPT on the primary side of SGs are also discussed. (author)

  6. Corrosion-product transport, oxidation state and remedial measures

    International Nuclear Information System (INIS)

    Sawicki, J.A.; Brett, M.E.; Tapping, R.L.

    1998-01-01

    The issues associated with monitoring and controlling corrosion-product transport (CPT) in the balance-of-plant (BOP) and steam generators (SG) of CANDU stations are briefly reviewed. The efforts are focused on minimizing corrosion of carbon steel, which is used extensively in the CANDU primary and secondary systems. Emphasis is placed on the corrosion-product oxidation state as a monitor of water chemistry effectiveness, and as a monitor of system corrosion effects. The discussion is based mostly on the results and observations from Ontario Hydro plants, and their comparisons with PWRs. The effects of low oxygen and elevated hydrazine chemistry are reviewed, as well as the effects of lay-up and various start-up conditions. Progress in monitoring electrochemical potential (ECP) at Ontario Hydro plants and its relationship to the oxidation state of corrosion products is reviewed. Observations on corrosion-product transport on the primary side of steam generators are also discussed. (author)

  7. Influence of oxidation state on the pH dependence of hydrous iridium oxide films

    International Nuclear Information System (INIS)

    Steegstra, Patrick; Ahlberg, Elisabet

    2012-01-01

    Many electrochemical reactions taking place in aqueous solution consume or produce protons. The pH in the diffusion layer can therefore be significantly altered during the reaction and there is a need for in situ pH measurements tracing this near surface pH. In the present paper the rotating ring disc technique was used to measure near surface pH changes during oxygen reduction, utilising hydrous iridium oxide as the pH sensing probe. Before such experiments a good understanding of the pH sensing properties of these films is required and the impact of the oxidation state of the film on the pH sensing properties was investigated as well as the influence of solution redox species. The pH sensitivity (depicted by dE/dpH) was found to depend on the average oxidation state of the film in a manner resembling the cyclic voltammetry response. In all cases the pH response is “supernernstian” with more than one proton per electron. The origin of this behaviour is discussed in the context of acid-base properties of the film and the existence of both hydrous and anhydrous oxide phases. The pH response depends also on the redox properties of the solution but can be optimised for various purposes by conditioning the film at different potentials. This was clearly illustrated by adding hydrogen peroxide, an intermediate in the oxygen reduction reaction, to the solution. It was shown that hydrous iridium oxide can be used as a reliable in situ pH sensor provided that care is taken to optimise the oxidation state of the film.

  8. Pentavalent Uranium Chemistry - Synthetic Pursuit Of A Rare Oxidation State

    Energy Technology Data Exchange (ETDEWEB)

    Graves, Christopher R [Los Alamos National Laboratory; Kiplinger, Jaqueline L [Los Alamos National Laboratory

    2009-01-01

    This feature article presents a comprehensive overview of pentavalent uranium systems in non-aqueous solution with a focus on the various synthetic avenues employed to access this unusual and very important oxidation state. Selected characterization data and theoretical aspects are also included. The purpose is to provide a perspective on this rapidly evolving field and identify new possibilities for future developments in pentavalent uranium chemistry.

  9. Study of uranium oxidation states in geological material.

    Science.gov (United States)

    Pidchenko, I; Salminen-Paatero, S; Rothe, J; Suksi, J

    2013-10-01

    A wet chemical method to determine uranium (U) oxidation states in geological material has been developed and tested. The problem faced in oxidation state determinations with wet chemical methods is that U redox state may change when extracted from the sample material, thereby leading to erroneous results. In order to quantify and monitor U redox behavior during the acidic extraction in the procedure, an analysis of added isotopic redox tracers, (236)U(VI) and (232)U(IV), and of variations in natural uranium isotope ratio ((234)U/(238)U) of indigenous U(IV) and U(VI) fractions was performed. Two sample materials with varying redox activity, U bearing rock and U-rich clayey lignite sediment, were used for the tests. The Fe(II)/Fe(III) redox-pair of the mineral phases was postulated as a potentially disturbing redox agent. The impact of Fe(III) on U was studied by reducing Fe(III) with ascorbic acid, which was added to the extraction solution. We observed that ascorbic acid protected most of the U from oxidation. The measured (234)U/(238)U ratio in U(IV) and U(VI) fractions in the sediment samples provided a unique tool to quantify U oxidation caused by Fe(III). Annealing (sample heating) to temperatures above 500 °C was supposed to heal ionizing radiation induced defects in the material that can disturb U redox state during extraction. Good agreement between two independent methods was obtained for DL-1a material: an average 38% of U(IV) determined by redox tracer corrected wet chemistry and 45% for XANES. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. The Merging Galaxy Cluster A520 - A Broken-Up Cool Core, A Dark Subcluster, and an X-Ray Channel

    Science.gov (United States)

    Wang, Qian H.S.; Markevitch, Maxim; Giacintucci, Simona

    2016-01-01

    We present results from a deep Chandra X-ray observation of a merging galaxy cluster A520. A high-resolution gas temperature map reveals a long trail of dense, cool clumpsapparently the fragments of a cool core that has been stripped from the infalling subcluster by ram pressure. The clumps should still be connected by the stretched magnetic field lines. The observed temperature variations imply that thermal conductivity is suppressed by a factor greater than 100 across the presumed direction of the magnetic field (as found in other clusters), and is also suppressed along the field lines by a factor of several. Two massive clumps in the periphery of A520, visible in the weak-lensing mass map and the X-ray image, have apparently been completely stripped of gas during the merger, but then re-accreted the surrounding high-entropy gas upon exit from the cluster. The mass clump that hosted the stripped cool core is also re-accreting hotter gas. An X-ray hydrostatic mass estimate for the clump that has the simplest geometry agrees with the lensing mass. Its current gas mass to total mass ratio is very low, 1.5 percent to 3 percent, which makes it a "dark subcluster." We also found a curious low X-ray brightness channel (likely a low-density sheet in projection) going across the cluster along the direction of an apparent secondary merger. The channel may be caused by plasma depletion in a region of an amplified magnetic field (with plasma Beta approximately equal to 10-20). The shock in A520 will be studied in a separate paper.

  11. Studies of the Tc oxidation states in humic acid solutions

    International Nuclear Information System (INIS)

    Wang Bo; Liu Dejun; Yao Jun

    2010-01-01

    The oxidation state is an important aspect of the speciation of Tc in groundwater that contained organic substances due to it control the precipitation, complexation, sorption and colloid formation behavior of the Tc under HWL geological disposal conditions. In present work, the oxidation states of Tc were investigated using the LaCl 3 coagulation method and solution extraction method in aqueous solutions in which the humic acid concentration range is from 0 to 20 mg L -1 and the Tc (Ⅶ) concentration range is about 10 -8 mol l -1 . The radiocounting of 99 Tc was determined using liquid scintillation spectrometry. The humic acid will influence the radiocounting ratio of 99 Tc apparently, however, the quenching effect can be restrained once keep the volume of the cocktail to about twenty times of the sample volume. The LaCl 3 coagulation methods were carried out for the investigation of Tc oxidation states in humic acid aqueous systems at about pH 8. The tetraphenylarsonium chloride (IPA)-chloroform extraction method was used also simultaneously to investigation the concentrations of Tc (Ⅳ) and Tc (Ⅶ) for the availability of the LaCl 3 precipitation method, and the experimental results demonstrate that tetravalent technetium and pertechnetate concentrations are well agreement with the LaCl 3 precipitation method. These two experimental results demonstrated that Tc (Ⅶ) is very stable in the Tc (Ⅶ)-humic acid system during a 350 days experimental period, and the Tc (Ⅳ) concentrations are very lower, that is indicate that there didn't oxidizing reactions between the Fluka humic acid and Tc (Ⅶ) in aqueous solutions under anaerobic conditions. That is means the presence of humic acids even in anaerobic groundwater is disadvantage for the retardance of radionuclides. (authors)

  12. Studies of Tc oxidation states in humic acid solutions

    International Nuclear Information System (INIS)

    Wang Bo; Liu Dejun; Yao Jun

    2011-01-01

    The oxidation state of Tc is an important aspect of the speciation in groundwater which contained organic substances due to it control the precipitation, complexation, sorption and colloid formation behavior of the Tc under HWL geological disposal conditions. In present work, the oxidation states of Tc were investigated using the LaCl 3 coagulation method and solution extraction method in aqueous solutions in which the humic acid concentration range is from 0 to 20 mg/L and the Tc (VII) concentration is about 10 -8 mol/L. The radiocounting of 99 Tc was determined using liquid scintillation spectrometry. The humic acid will influence the radiocounting ratio of 99 Tc apparently, however, the quenching effect can be restrained once keep the volume of the cocktail to about twenty times of the sample volume. The LaCl 3 coagulation method was carried out for the investigation of Tc oxidation states in humic acid aqueous systems at about pH 8. The tetraphenylarsonium chloride (TPA)-chloroform extraction method was used also simultaneously to investigation the concentrations of Tc (IV) and Tc (VII) for the availability of the LaCl 3 precipitation method, and the experimental results demonstrate that tetravalent technetium and pertechnetate concentration are well agreement with the LaCl 3 precipitation method. These two experimental results demonstrated that Tc (VII) is very stable in the Tc (VII)-humic acid system during a 350 days experimental period, and the Tc (IV) concentrations are very lower, that is indicate that there didn't oxidizing reactions between the Fluka humic acid and Tc (VII) in aqueous solutions under anaerobic conditions. That means the presence of humic acids even in anaerobic groundwater is disadvantage for the retardance of radionuclides. (authors)

  13. Study on the solid state chemistry of ternary uranium oxides

    International Nuclear Information System (INIS)

    Yamashita, Toshiyuki

    1988-03-01

    With the increase of burnup of uranium oxide fuels, various kinds of fission products are formed, and the oxygen atoms combined with the consumed heavy atoms are freed. The solid state chemical and/or thermodynamic properties of these elements at high temperatures are complex, and have not been well clarified. In the present report, an approach was taken that the chemical interactions between UO 2 and these fission products can be regarded as causing overlapped effects of composing ternary uranium oxides, and formation reactions and phase behavior were studied for several ternary uranium oxides with typical fission product elements such as alkaline earth metals and rare earth elements. Precise determination methods for the composition of ternary uranium oxides were developed. The estimated accuracies for x and y values in M y U 1-y O 2+x were ± 0.006 and ± 0.004, respectively. The thermodynamic properties and the lattice parameters of the phases in the Ca-U-O and Pr-U-O systems were discussed in relation to the composition determined by the methods. Crystal structure analyses of cadmium monouranates were made with X-ray diffraction method. (author) 197 refs

  14. Optoelectronic properties of valence-state-controlled amorphous niobium oxide

    Science.gov (United States)

    Onozato, Takaki; Katase, Takayoshi; Yamamoto, Akira; Katayama, Shota; Matsushima, Koichi; Itagaki, Naho; Yoshida, Hisao; Ohta, Hiromichi

    2016-06-01

    In order to understand the optoelectronic properties of amorphous niobium oxide (a-NbO x ), we have investigated the valence states, local structures, electrical resistivity, and optical absorption of a-NbO x thin films with various oxygen contents. It was found that the valence states of Nb ion in a-NbO x films can be controlled from 5+  to 4+  by reducing oxygen pressure during film deposition at room temperature, together with changing the oxide-ion arrangement around Nb ion from Nb2O5-like to NbO2-like local structure. As a result, a four orders of magnitude reduction in the electrical resistivity of a-NbO x films was observed with decreasing oxygen content, due to the carrier generation caused by the appearance and increase of an oxygen-vacancy-related subgap state working as an electron donor. The tunable optoelectronic properties of a-NbO x films by valence-state-control with oxygen-vacancy formation will be useful for potential flexible optoelectronic device applications.

  15. Predicting spent fuel oxidation states in a tuff repository

    International Nuclear Information System (INIS)

    Einziger, R.E.; Woodley, R.E.

    1987-01-01

    Nevada Nuclear Waste Storage Investigations Project (NNWSI) is studying the suitability of the tuffaceous rocks at Yucca Mountain as a waste repository for spent fuel disposal. The oxidation state of the LWR spent fuel in the moist air environment of a tuff repository could be a significant factor in determining its leaching and dissolution characteristics. Predictions as to which oxidation states would be present are important in analyzing such a repository and thus the present study was undertaken. A set of TGA (thermogravimetric analysis) tests were conducted on well-controlled samples of irradiated PWR fuel with time and temperature as the only variables. The tests were conducted between 140 and 225 0 C for a duration up to 2200 hours. The weight gain curves were analyzed in terms of diffusion through a layer of U 3 O 7 , diffusion into the grains to form a solid solution, a simplified empirical representation of a combination of grain boundary diffusion and bulk grain oxidation. Reaction rate constants were determined in each case, but analysis of these data could not establish a definitive mechanism. 21 refs., 10 figs., 3 tabs

  16. The oxidation state of sulfur in apatite: A new oxybarometer?

    Science.gov (United States)

    Fiege, A.; Konecke, B.; Kim, Y.; Simon, A. C.; Becker, U.; Parat, F.

    2016-12-01

    Oxygen fugacity (fO2) of magmatic and hydrothermal systems influences, for instance, crystallization and degassing processes as well as metal solubilities in melts and fluids. Apatite is a ubiquitous mineral in magmatic and hydrothermal environments that can record and preserve volatile zonation. It can contain several thousand μg/g of the redox sensitive element sulfur (S), making S-in-apatite a potential fO2 sensor. Despite the polyvalent properties of S (e.g., S2-, S4+, S6+), the oxidation state and incorporation mechanisms of S in the apatite structure are poorly understood. In this study, the oxidation state of S-in-apatite as a function of fO2 is investigated using X-ray absorption near-edge structures (XANES) spectroscopy at the S K-edge. Apatites crystallized from lamproitic melts at 1000°C, 300 MPa and over a broad range of fO2 and sulfur fugacities (fS2) were measured. Peaks corresponding to S6+ ( 2482 eV), S4+ ( 2478 eV) and S2- ( 2470 eV) were identified in apatite. The integrated S6+/STotal (STotal = S6+ + S4+ + S2-) peak area ratios show a distinct positive correlation with fO2, increasing from 0.17 at FMQ+0 to 0.96 at FMQ+3. Ab-initio calculations were performed to further understand the energetics and geometry of incorporation of S6+, S4+ and S2- into the apatite (F-, Cl-, OH-) end-members. The results confirm that apatite can contain three different oxidations states of S (S6+, S4+, S2-) as a function of fO2. This makes apatite probably the first geologically relevant mineral to incorporate reduced (S2-), intermediate (S4+), and oxidized (S6+) S in variable proportions. We emphasize that the strong dependence of the S oxidation state in apatite as a function of fO2 is also coupled with changing S content of apatite and co-existing melt (i.e., with changing fS2), resulting in a complex correlation between [1] apatite-melt (or fluid) partitioning, [2] redox conditions and [3] the melt and/or fluid composition, making the application of previously

  17. 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.

  18. Synthesis and characterization of ruthenium fluorides and oxide fluorides with high oxidation states

    International Nuclear Information System (INIS)

    Meublat, L.

    1989-10-01

    The synthesis of ruthenium fluorides and oxide fluorides with high oxidation states was attempted from dioxide RuO 2 and tetroxide RuO 4 . Three fluorinating agents were used: fluorine, chlorine trifluoride and krypton difluoride. The reactions were achieved in anhydrous hydrogen fluoride at room temperature. Thus, the reaction of RuO 4 with CIF 3 enabled us to prepare chloryl hexafluororuthenate (V), CIO 2 + RuF 6 - , a new compound well identified by vibrational spectroscopy (infra-red and Raman), the structure of which was determined. The reaction of KrF 2 with RuO 4 gave the oxide tetrafluoride RuOF 4 , the previously published syntheses and properties of which were not in agreement with each other. This compound was definitely characterized here by chemical analysis, infra-red spectroscopy and X-ray powder diffraction. The product of thermal decomposition (70 0 C) of RuOF 4 is presumably RuF 4 since only oxygen is liberated during this decomposition. At last, the reaction of KrF 2 with RuO 2 probably leads to the formation of the new oxide fluoride RuO 2 F 4 . Indeed, no oxygen is given off during this reaction, the chemical analysis of the red-orange coloured solid residue is almost in agreement with the one proposed and its infra-red absorption spectrum indicates the presence of ruthenium-oxygen and ruthenium-terminal and bridging fluorine bonds [fr

  19. Synthesis and characterization of ruthenium fluorides and oxide fluorides with high oxidation states

    International Nuclear Information System (INIS)

    Meublat, L.

    1989-01-01

    The synthesis of ruthenium fluorides and oxide fluorides with high oxidation states was attempted from dioxide RuO 2 and tetroxide RuO 4 . Three fluorinating agents were used: fluorine, chlorine trifluoride and krypton difluoride. The reactions were achieved in anhydrous hydrogen fluoride at room temperature. Thus, the reaction of RuO 4 with CIF 3 enabled us to prepare chloryl hexafluororuthenate (V), ClO 2 + RuF 6 - , a new compound well idendified by vibrational spectroscopy (infra-red and Raman), the structure of which was determined. The reaction of KrF 2 with RuO 4 gave the oxide tetrafluoride RuOF 4 , the previously published syntheses and properties of which were not in agreement with each other. This compound was definitely characterized here by chemical analysis, infra-red spectroscopy and X-ray powder diffraction. The product of thermal decomposition (70 0 C) of RuOF 4 is presumably RuF 4 since only oxygen is liberated during this decomposition. At last, the reaction of KrF 2 with RuO 2 probably leads to the formation of the new oxide fluoride RuO 2 F 4 . Indeed, no oxygen is given off during this reaction, the chemical analysis of the red-orange coloured solid residue is almost in agreement with the one proposed and its infra-red absorption spectrum indicates the presence of ruthenium-oxygen and ruthenium-terminal and bridging fluorine bonds [fr

  20. Intestinal Oxidative State Can Alter Nutrient and Drug Bioavailability

    Directory of Open Access Journals (Sweden)

    Faria Ana

    2009-01-01

    Full Text Available Organic cations (OCs are substances of endogenous (e.g., dopamine, choline or exogenous (e.g., drugs like cimetidine origin that are positively charged at physiological ph. since many of these compounds can not pass the cell membrane freely, their transport in or out of cells must be mediated by specific transport systems. Transport by organic cation transporters (OCTs can be regulated rapidly by altering their trafficking and/or affinities in response to stimuli. However, for example, a specific disease could lead to modifications in the expression of OCTs. Chronic exposure to oxidative stress has been suggested to alter regulation and functional activity of proteins through several pathways. According to results from a previous work, oxidation-reduction pathways were thought to be involved in intestinal organic cation uptake modulation. The present work was performed in order to evaluate the influence of oxidative stressors, especially glutathione, on the intestinal organic cation absorption. For this purpose, the effect of compounds with different redox potential (glutathione, an endogenous antioxidant, and procyanidins, diet antioxidants was assessed on MPP+ (1-methyl-4-phenylpyridinium iodide uptake in an enterocyte cell line (Caco-2. Caco-2 cells were subcultured with two different media conditions (physiological: 5 mM glucose, referred as control cells; and high-glucose: 25 mM glucose, referred as HG cells. In HG cells, the uptake was significantly lower than in control cells. Redox changing interventions affected Mpp+ uptake, both in control and in high-glucose Caco-2 cells. Cellular glutathione levels could have an important impact on membrane transporter activity. The results indicate that modifications in the cellular oxidative state modulate MPP+ uptake by Caco-2 cells. Such modifications may reflect in changes of nutrient and drug bioavailability.

  1. Persistence of oxidation state III of gold in thione coordination

    Science.gov (United States)

    Jääskeläinen, Sirpa; Koskinen, Laura; Kultamaa, Matti; Haukka, Matti; Hirva, Pipsa

    2017-05-01

    Ligands N,N'-tetramethylthiourea and 2-mercapto-1-methyl-imidazole form stable Au(III) complexes [AuCl3(N,N'-tetramethylthiourea)] (1) and [AuCl3(2-mercapto-1-methyl-imidazole)] (2) instead of reducing the Au(III) metal center into Au(I), which would be typical for the attachment of sulfur donors. Compounds 1 and 2 were characterized by spectroscopic methods and by X-ray crystallography. The spectroscopic details were explained by simulation of the UV-Vis spectra via the TD-DFT method. Additionally, computational DFT studies were performed in order to find the reason for the unusual oxidation state in the crystalline materials. The preference for Au(III) can be explained via various weak intra- and intermolecular interactions present in the solid state structures. The nature of the interactions was further investigated by topological charge density analysis via the QTAIM method.

  2. Proteomic indicators of oxidation and hydration state in colorectal cancer

    Directory of Open Access Journals (Sweden)

    Jeffrey M. Dick

    2016-07-01

    Full Text Available New integrative approaches are needed to harness the potential of rapidly growing datasets of protein expression and microbial community composition in colorectal cancer. Chemical and thermodynamic models offer theoretical tools to describe populations of biomacromolecules and their relative potential for formation in different microenvironmental conditions. The average oxidation state of carbon (ZC can be calculated as an elemental ratio from the chemical formulas of proteins, and water demand per residue ( ${\\overline{n}}_{{\\mathrm{H}}_{2}\\mathrm{O}}$ n ¯ H 2 O is computed by writing the overall formation reactions of proteins from basis species. Using results reported in proteomic studies of clinical samples, many datasets exhibit higher mean ZC or ${\\overline{n}}_{{\\mathrm{H}}_{2}\\mathrm{O}}$ n ¯ H 2 O of proteins in carcinoma or adenoma compared to normal tissue. In contrast, average protein compositions in bacterial genomes often have lower ZC for bacteria enriched in fecal samples from cancer patients compared to healthy donors. In thermodynamic calculations, the potential for formation of the cancer-related proteins is energetically favored by changes in the chemical activity of H2O and fugacity of O2 that reflect the compositional differences. The compositional analysis suggests that a systematic change in chemical composition is an essential feature of cancer proteomes, and the thermodynamic descriptions show that the observed proteomic transformations in host tissue could be promoted by relatively high microenvironmental oxidation and hydration states.

  3. Composition and oxidation state of sulfur in atmospheric particulate matter

    Directory of Open Access Journals (Sweden)

    A. F. Longo

    2016-10-01

    Full Text Available The chemical and physical speciation of atmospheric sulfur was investigated in ambient aerosol samples using a combination of sulfur near-edge x-ray fluorescence spectroscopy (S-NEXFS and X-ray fluorescence (XRF microscopy. These techniques were used to determine the composition and oxidation state of sulfur in common primary emission sources and ambient particulate matter collected from the greater Atlanta area. Ambient particulate matter samples contained two oxidation states: S0 and S+VI. Ninety-five percent of the individual aerosol particles (> 1 µm analyzed contain S0. Linear combination fitting revealed that S+VI in ambient aerosol was dominated by ammonium sulfate as well as metal sulfates. The finding of metal sulfates provides further evidence for acidic reactions that solubilize metals, such as iron, during atmospheric transport. Emission sources, including biomass burning, coal fly ash, gasoline, diesel, volcanic ash, and aerosolized Atlanta soil, and the commercially available bacterium Bacillus subtilis, contained only S+VI. A commercially available Azotobacter vinelandii sample contained approximately equal proportions of S0 and S+VI. S0 in individual aerosol particles most likely originates from primary emission sources, such as aerosolized bacteria or incomplete combustion.

  4. Oxidation states of Fe and Ti in blue sapphire

    International Nuclear Information System (INIS)

    Wongrawang, P; Wongkokua, W; Monarumit, N; Thammajak, N; Wathanakul, P

    2016-01-01

    X-ray absorption near-edge spectroscopy (XANES) can be used to study the oxidation state of a dilute system such as transition metal defects in solid-state samples. In blue sapphire, Fe and Ti are defects that cause the blue color. Inter-valence charge transfer (IVCT) between Fe 2+ and Ti 4+ has been proposed to describe the optical color’s origin. However, the existence of divalent iron cations has not been thoroughly investigated. Fluorescent XANES is therefore employed to study K-edge absorptions of Fe and Ti cations in various blue sapphire samples including natural, synthetic, diffused and heat-treated sapphires. All the samples showed an Fe absorption edge at 7124 eV, corresponding to the Fe 3+ state; and Ti at 4984 eV, corresponding to Ti 4+ . From these results, we propose Fe 3+ -Ti 4+ mixed acceptor states located at 1.75 eV and 2.14 eV above the valence band of corundum, that correspond to 710 nm and 580 nm bands of UV–vis absorption spectra, to describe the cause of the color of blue sapphire. (paper)

  5. Determination of the oxidation states of metals and metalloids: An analytical review

    Science.gov (United States)

    Vodyanitskii, Yu. N.

    2013-12-01

    The hazard of many heavy metals/metalloids in the soil depends on their oxidation state. The problem of determining the oxidation state has been solved due to the use of synchrotron radiation methods with the analysis of the X-ray absorption near-edge structure (XANES). The determination of the oxidation state is of special importance for some hazardous heavy elements (arsenic, antimony, selenium, chromium, uranium, and vanadium). The mobility and hazard of each of these elements depend on its oxidation state. The mobilities are higher at lower oxidation states of As, Cr, V, and Se and at higher oxidation states of Sb and U. The determination of the oxidation state of arsenic has allowed revealing its fixation features in the rhizosphere of hydrophytes. The known oxidation states of chromium and uranium are used for the retention of these elements on geochemical barriers. Different oxidation states have been established for vanadium displacing iron in goethite. The determination of the oxidation state of manganese in the rhizosphere and the photosynthetic apparatus of plants is of special importance for agricultural chemists.

  6. Influence of vanadium oxidation states on the performance of V-Mg-Al mixed-oxide catalysts for the oxidative dehydrogenation of propane

    International Nuclear Information System (INIS)

    Schacht, L.; Navarrete, J.; Schacht, P.; Ramirez, M. A.

    2010-01-01

    V-Mg-Al mixed-oxide catalysts for oxidative dehydrogenation of propane were prepared by thermal decomposition of Mg-Al-layered double hydroxides with vanadium interlayer doping. The obtained catalysts were tested for the oxidative dehydrogenation of propane, obtaining good results in catalytic activity (conversion 16.55 % and selectivity 99.97 %) Results indicated that catalytic performance of these materials depends on how vanadium is integrated in the layered structure, which is determined by the Mg/Al ratio. Vanadium interlayer doping modifies the oxidation state of vanadium and consequently catalytic properties. Surface properties were studied by X-ray photoelectron spectroscopic and diffuse reflectance, UV-visible spectroscopy, and temperature programmed reduction. The analyses provided information about the oxidation state, before and after the reaction. From these results, it is suggested that selectivity to propylene and catalytic activity depend mainly of vanadium oxidation state. (Author)

  7. Influence of vanadium oxidation states on the performance of V-Mg-Al mixed-oxide catalysts for the oxidative dehydrogenation of propane

    Energy Technology Data Exchange (ETDEWEB)

    Schacht, L. [IPN, Escuela Superior de Fisica y Matematicas, Departamento de Ciencia de Materiales, Av. IPN s/n, Edificio 9, Col. Lindavista, 07738 Mexico D. F. (Mexico); Navarrete, J.; Schacht, P.; Ramirez, M. A., E-mail: pschacha@imp.m [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas No. 152, 07730 Mexico D. F. (Mexico)

    2010-07-01

    V-Mg-Al mixed-oxide catalysts for oxidative dehydrogenation of propane were prepared by thermal decomposition of Mg-Al-layered double hydroxides with vanadium interlayer doping. The obtained catalysts were tested for the oxidative dehydrogenation of propane, obtaining good results in catalytic activity (conversion 16.55 % and selectivity 99.97 %) Results indicated that catalytic performance of these materials depends on how vanadium is integrated in the layered structure, which is determined by the Mg/Al ratio. Vanadium interlayer doping modifies the oxidation state of vanadium and consequently catalytic properties. Surface properties were studied by X-ray photoelectron spectroscopic and diffuse reflectance, UV-visible spectroscopy, and temperature programmed reduction. The analyses provided information about the oxidation state, before and after the reaction. From these results, it is suggested that selectivity to propylene and catalytic activity depend mainly of vanadium oxidation state. (Author)

  8. Manganese oxidation state mediates toxicity in PC12 cells

    International Nuclear Information System (INIS)

    Reaney, S.H.; Smith, D.R.

    2005-01-01

    The role of the manganese (Mn) oxidation state on cellular Mn uptake and toxicity is not well understood. Therefore, undifferentiated PC12 cells were exposed to 0-200 μM Mn(II)-chloride or Mn(III)-pyrophosphate for 24 h, after which cellular manganese levels were measured along with measures of cell viability, function, and cytotoxicity (trypan blue exclusion, medium lactate dehydrogenase (LDH), 8-isoprostanes, cellular ATP, dopamine, serotonin, H-ferritin, transferrin receptor (TfR), Mn-superoxide dismutase (MnSOD), and copper-zinc superoxide dismutase (CuZnSOD) protein levels). Exposures to Mn(III) >10 μM produced 2- to 5-fold higher cellular manganese levels than equimolar exposures to Mn(II). Cell viability and ATP levels both decreased at the highest Mn(II) and Mn(III) exposures (150-200 μM), while Mn(III) exposures produced increases in LDH activity at lower exposures (≥50 μM) than did Mn(II) (200 μM only). Mn(II) reduced cellular dopamine levels more than Mn(III), especially at the highest exposures (50% reduced at 200 μM Mn(II)). In contrast, Mn(III) produced a >70% reduction in cellular serotonin at all exposures compared to Mn(II). Different cellular responses to Mn(II) exposures compared to Mn(III) were also observed for H-ferritin, TfR, and MnSOD protein levels. Notably, these differential effects of Mn(II) versus Mn(III) exposures on cellular toxicity could not simply be accounted for by the different cellular levels of manganese. These results suggest that the oxidation state of manganese exposures plays an important role in mediating manganese cytotoxicity

  9. Measurement of soil carbon oxidation state and oxidative ratio by 13C nuclear magnetic resonance

    Science.gov (United States)

    Hockaday, W.C.; Masiello, C.A.; Randerson, J.T.; Smernik, R.J.; Baldock, J.A.; Chadwick, O.A.; Harden, J.W.

    2009-01-01

    The oxidative ratio (OR) of the net ecosystem carbon balance is the ratio of net O2 and CO2 fluxes resulting from photosynthesis, respiration, decomposition, and other lateral and vertical carbon flows. The OR of the terrestrial biosphere must be well characterized to accurately estimate the terrestrial CO2 sink using atmospheric measurements of changing O2 and CO2 levels. To estimate the OR of the terrestrial biosphere, measurements are needed of changes in the OR of aboveground and belowground carbon pools associated with decadal timescale disturbances (e.g., land use change and fire). The OR of aboveground pools can be measured using conventional approaches including elemental analysis. However, measuring the OR of soil carbon pools is technically challenging, and few soil OR data are available. In this paper we test three solid-state nuclear magnetic resonance (NMR) techniques for measuring soil OR, all based on measurements of the closely related parameter, organic carbon oxidation state (Cox). Two of the three techniques make use of a molecular mixing model which converts NMR spectra into concentrations of a standard suite of biological molecules of known C ox. The third technique assigns Cox values to each peak in the NMR spectrum. We assess error associated with each technique using pure chemical compounds and plant biomass standards whose Cox and OR values can be directly measured by elemental analyses. The most accurate technique, direct polarization solid-state 13C NMR with the molecular mixing model, agrees with elemental analyses to ??0.036 Cox units (??0.009 OR units). Using this technique, we show a large natural variability in soil Cox and OR values. Soil Cox values have a mean of -0.26 and a range from -0.45 to 0.30, corresponding to OR values of 1.08 ?? 0.06 and a range from 0.96 to 1.22. We also estimate the OR of the carbon flux from a boreal forest fire. Analysis of soils from nearby intact soil profiles imply that soil carbon losses associated

  10. The problem of oxidation state stabilisation and some regularities of a Periodic system of the elements

    International Nuclear Information System (INIS)

    Kiselev, Yurii M; Tretyakov, Yuri D

    1999-01-01

    The general principles of the concept of oxidation state stabilisation are formulated. Problems associated with the preparation and provision of the highest valent forms of transition elements are considered. The empirical data concerning the synthesis of new compounds of rare-earth elements and d elements in unusually high oxidation states are analysed. The possibility of occurrence of the oxidation states + 9 and + 10 for some elements (for example, for iridium and platinum in tetraoxo ions) are discussed. Approaches to the realisation of these states are outlined and it is demonstrated that solid phases or matrices containing alkali metal cations are the most promising systems for the stabilisation of these high oxidation states. Selected thermodynamic features typical of metal halides and oxides and the regularities of the changes in the extreme oxidation states of d elements are considered. The bibliography includes 266 references.

  11. Effect of particle size on iron nanoparticle oxidation state

    International Nuclear Information System (INIS)

    Lombardo, Jeffrey J.; Lysaght, Andrew C.; Goberman, Daniel G.; Chiu, Wilson K.S.

    2012-01-01

    Selecting catalyst particles is a very important part of carbon nanotube growth, although the properties of these nanoscale particles are unclear. In this article iron nanoparticles are analyzed through the use of atomic force microscopy and x-ray photoelectron spectroscopy in order to understand how the size affects the chemical composition of nanoparticles and thus their physical structure. Initially, atomic force microscopy was used to confirm the presence of iron particles, and to determine the average size of the particles. Next an analytical model was developed to estimate particle size as a function of deposition time using inputs from atomic force microscopy measurement. X-ray photoelectron spectroscopy analysis was then performed with a focus on the spectra relating to the 2p Fe electrons to study the chemical state of the particles as a function of time. It was shown that as the size of nanoparticles decreased, the oxidation state of the particles changed due to a high proportion of atoms on the surface.

  12. Quantum confinement-induced tunable exciton states in graphene oxide.

    Science.gov (United States)

    Lee, Dongwook; Seo, Jiwon; Zhu, Xi; Lee, Jiyoul; Shin, Hyeon-Jin; Cole, Jacqueline M; Shin, Taeho; Lee, Jaichan; Lee, Hangil; Su, Haibin

    2013-01-01

    Graphene oxide has recently been considered to be a potential replacement for cadmium-based quantum dots due to its expected high fluorescence. Although previously reported, the origin of the luminescence in graphene oxide is still controversial. Here, we report the presence of core/valence excitons in graphene-based materials, a basic ingredient for optical devices, induced by quantum confinement. Electron confinement in the unreacted graphitic regions of graphene oxide was probed by high resolution X-ray absorption near edge structure spectroscopy and first-principles calculations. Using experiments and simulations, we were able to tune the core/valence exciton energy by manipulating the size of graphitic regions through the degree of oxidation. The binding energy of an exciton in highly oxidized graphene oxide is similar to that in organic electroluminescent materials. These results open the possibility of graphene oxide-based optoelectronic device technology.

  13. Solid state solubility of copper oxides in hydroxyapatite

    Science.gov (United States)

    Zykin, Mikhail A.; Vasiliev, Alexander V.; Trusov, Lev A.; Dinnebier, Robert E.; Jansen, Martin; Kazin, Pavel E.

    2018-06-01

    Samples containing copper oxide doped hydroxyapatite with the composition Ca10(PO4)6(CuxOH1-x-δ)2, x = 0.054 - 0.582, in the mixture with CuO/Cu2O were prepared by a solid-state high-temperature treatment at varying annealing temperatures and at different partial water vapor and oxygen pressures. The crystal structures of the apatite compounds were refined using powder X-ray diffraction patterns and the content of copper ions x in the apatite was determined. Copper ions enter exclusively into the apatite trigonal channels formally substituting protons of OH-groups and the hexagonal cell parameters grow approximately linearly with x, the channel volume mostly expanding while the remaining volume of the crystal lattice changing only slightly. The equilibrium copper content in the apatite increases drastically, by almost a factor of 10 with the annealing temperature rising from 800° to 1200°C. The reduction of the water partial pressure leads to a further increase of x, while the dependence of x on the oxygen partial pressure exhibits a maximum. The observed relations are consistent with the proposed chemical reactions implying the copper introduction is followed by the release of a considerable quantity of gaseous products - water and oxygen. The analysis of interatomic distances suggests that the maximum content of copper ions in the channel cannot exceed 2/3.

  14. Stabilization of actinides and lanthanides in unusually high oxidation states

    International Nuclear Information System (INIS)

    Eller, P.G.; Penneman, R.A.

    1986-01-01

    Chemical environments can be chosen which stabilize actinides and lanthanides in unusually high or low oxidation states and in unusual coordination. In many cases, one can rationalize the observed species as resulting from strong charge/size influences provided by specific sites in host lattices (e.g., Tb(IV) in BaTbO 3 or Am(IV) in polytungstate anions). In other cases, the unusual species can be considered from an acid-base viewpoint (e.g., U(III) in AsF 5 /HF solution or Pu(VII) in Li 5 PuO 6 ). In still other cases, an interplay of steric and redox effects can lead to interesting comparisons (e.g., instability of double fluoride salts of Pu(V) and Pu(VI) relative to U, Np, and Am analogues). Generalized ways to rationalize compounds containing actinides and lanthanides in unusual valences (particularly high valences), including the above and numerous other examples, will form the focus of this paper. Recently developed methods for synthesizing high valent f-element fluorides using superoxidizers and superacids at low temperatures will also be described. 65 refs., 8 figs., 9 tabs

  15. The Behavior of the Ru-bda Water Oxidation Catalysts at Low Oxidation States.

    Science.gov (United States)

    Matheu, Roc; Ghaderian, Abolfazl; Francas, Laia; Chernev, Petko; Ertem, Mehmed; Benet-Buchholz, Jordi; Batista, Victor; Haumann, Michael; Gimbert-Suriñach, Carolina; Sala, Xavier; Llobet, Antoni

    2018-06-13

    The Ru complex [RuII(bda-κ-N2O2)(N-NH2)2], 1, (bda2- = (2,2'-bipyridine)-6,6'-dicarboxylate; N-NH2 = 4-(pyridin-4-yl)aniline) is used as a synthetic intermediate to prepare Ru-bda complexes that contain the NO+, acetonitrile (MeCN) or H2O ligands at oxidation states II and III. Complex 1 reacts with excess NO+ to form a Ru complex where the aryl amine ligands N-NH2 in 1 are transformed into diazonium salts (N-N2+ = 4-(pyridin-4-yl)benzenediazonium)) together with the formation of a new Ru-NO group at the equatorial zone, to generate [RuII(bda-κ-N2O)(NO)(N-N2)2]3+, 23+. Similarly, complex 1 can also react with a coordinating solvent, such as MeCN, at room temperature leading to complex [RuII(bda-κ-N2O)(MeCN)(N-NH2)2], 3. Finally in acidic aqueous solutions solvent water coordinates the Ru center forming {[RuII(bda-κ-(NO)3)(H2O)(N-NH3)2](H2O)n}2+, 42+, that is strongly hydrogen bonded with additional water molecules at the second coordination sphere. We have additionally characterized the one electron oxidized complex {[RuIII(bda-κ-(NO)3.5)(H2O)(N-NH3)2](H2O)n}3+, 53+. The coordination mode of the complexes has been studied both in the solid state and in solution through single-crystal XRD, X-ray absorption spectroscopy, variable-temperature NMR and DFT calculations. While the κ-N2O is the main coordination mode for 23+ and 3, an equilibrium that involves isomers with κ-N2O and κ-NO2 coordination modes and neighboring hydrogen bonded water molecules is observed for 42+ and 53+. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. A microbial-mineralization-inspired approach for synthesis of manganese oxide nanostructures with controlled oxidation states and morphologies

    Energy Technology Data Exchange (ETDEWEB)

    Oba, Manabu; Oaki, Yuya; Imai, Hiroaki [Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan)

    2010-12-21

    Manganese oxide nanostructures are synthesized by a route inspired by microbial mineralization in nature. The combination of organic molecules, which include antioxidizing and chelating agents, facilitates the parallel control of oxidation states and morphologies in an aqueous solution at room temperature. Divalent manganese hydroxide (Mn(OH){sub 2}) is selectively obtained as a stable dried powder by using a combination of ascorbic acid as an antioxidizing agent and other organic molecules with the ability to chelate to manganese ions. The topotactic oxidation of the resultant Mn(OH){sub 2} leads to the selective formation of trivalent manganese oxyhydroxide ({beta}-MnOOH) and trivalent/tetravalent sodium manganese oxide (birnessite, Na{sub 0.55}Mn{sub 2}O{sub 4}.1.5H{sub 2}O). For microbial mineralization in nature, similar synthetic routes via intermediates have been proposed in earlier works. Therefore, these synthetic routes, which include in the present study the parallel control over oxidation states and morphologies of manganese oxides, can be regarded as new biomimetic routes for synthesis of transition metal oxide nanostructures. As a potential application, it is demonstrated that the resultant {beta}-MnOOH nanostructures perform as a cathode material for lithium ion batteries. (Copyright copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Oxidation under electron bombardment. A tool for studying the initial states of silicon oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Carriere, B.; Deville, J.P.; El Maachi, A.

    1987-06-01

    The exciting beam of an Auger electron spectrometer has been used to monitor the oxidation of silicon single crystals at room temperature and very low pressures of oxygen (approx. 10/sup -7/ Torr). This process allows us to build ultra-thin layers of silica on silicon (down to 30 A) but it is mostly used to investigate the mechanisms of the initial stages of oxidation. Auger spectra recorded continuously during the oxidation process provide information on (1) the nature of the silicon-oxygen chemical bonds which are interpreted through fine structure in the Auger peak, and (2) the kinetics of oxide formation which are deduced from curves of Auger signal versus time. An account is given of the contribution of these Auger studies to the description of the intermediate oxide layer during the reaction between silicon and oxygen and the influence of surface structural disorder, induced mainly by argon-ion bombardment, is discussed in terms of reactivity and oxide coverage.

  18. Interface Controlled Oxidation States in Layered Cobalt Oxide Nanoislands on Gold

    DEFF Research Database (Denmark)

    Walton, Alexander; Fester, Jakob; Bajdich, Michal

    2015-01-01

    Layered cobalt oxides have been shown to be highly active catalysts for the oxygen evolution reaction (OER; half of the catalytic “water splitting” reaction), particularly when promoted with gold. However, the surface chemistry of cobalt oxides and in particular the nature of the synergistic effect...

  19. Origin of interface states and oxide charges generated by ionizing radiation

    International Nuclear Information System (INIS)

    Sah, C.T.

    1976-01-01

    The randomly located trivalent silicon atoms are shown to account for the thermally generated interface states at the SiO 2 -Si interface. The interface state density is greatly reduced in water containing ambients at low temperatures (450 0 C) by forming trivalent silicon hydroxide bonds. Interface states are regenerated when the /triple bond/Si-OH bonds are broken by ionizing radiation and the OH ions are drifted away. In the bulk of the oxide film, the trivalent silicon and the interstitial oxygen donor centers are shown to be responsible for the heat and radiation generated positive space charge build-up (oxide charge) in thermally grown silicon oxide

  20. Towards a Predictive Thermodynamic Model of Oxidation States of Uranium Incorporated in Fe (hydr) oxides

    Energy Technology Data Exchange (ETDEWEB)

    Bagus, Paul S. [Univ. of North Texas, Denton, TX (United States)

    2013-01-01

    -Level Excited States: Consequences For X-Ray Absorption Spectroscopy”, J. Elec. Spectros. and Related Phenom., 200, 174 (2015) describes our first application of these methods. As well as applications to problems and materials of direct interest for our PNNL colleagues, we have pursued applications of fundamental theoretical significance for the analysis and interpretation of XPS and XAS spectra. These studies are important for the development of the fields of core-level spectroscopies as well as to advance our capabilities for applications of interest to our PNNL colleagues. An excellent example is our study of the surface core-level shifts, SCLS, for the surface and bulk atoms of an oxide that provides a new approach to understanding how the surface electronic of oxides differs from that in the bulk of the material. This work has the potential to lead to a new key to understanding the reactivity of oxide surfaces. Our theoretical studies use cluster models with finite numbers of atoms to describe the properties of condensed phases and crystals. This approach has allowed us to focus on the local atomistic, chemical interactions. For these clusters, we obtain orbitals and spinors through the solution of the Hartree-Fock, HF, and the fully relativistic Dirac HF equations. These orbitals are used to form configuration mixing wavefunctions which treat the many-body effects responsible for the open shell angular momentum coupling and for the satellites of the core-level spectra. Our efforts have been in two complementary directions. As well as the applications described above, we have placed major emphasis on the enhancement and extension of our theoretical and computational capabilities so that we can treat complex systems with a greater range of many-body effects. Noteworthy accomplishments in terms of method development and enhancement have included: (1) An improvement in our treatment of the large matrices that must be handled when many-body effects are treated. (2

  1. Ion bombardment effects on surface states in selected oxide systems: rutile and alkaline earth titanates

    International Nuclear Information System (INIS)

    Gruen, D.M.

    1978-01-01

    In this paper, the nature of the surface states of n-type TiO 2 and SrTiO 3 is discussed and the role of ion bombardment in modifying the properties of these states is elucidated. Insofar as possible, the interrelationships between oxide nonstoichiometry, surface states, ion bombardment effects and photoelectrolysis are explored

  2. Oxidation Kinetics of Copper: An Experiment in Solid State Chemistry.

    Science.gov (United States)

    Ebisuzaki, Y.; Sanborn, W. B.

    1985-01-01

    Oxidation kinetics in metals and the role defects play in diffusion-controlled reactions are discussed as background for a junior/senior-level experiment in the physical or inorganic chemistry laboratory. Procedures used and typical data obtained are provided for the experiment. (JN)

  3. Plutonium uptake by Scenedesmus obliquus as a function of isotope and oxidation state

    International Nuclear Information System (INIS)

    Tkacik, M.F.; Giesy, J.P.; Wilhite, E.L.; Corey, J.C.

    1979-01-01

    Uptake of 238 Pu 4+ , 238 Pu 6+ , 239 Pu 4+ and 239 Pu 6+ by the green alga Scenedesmus obliquus (Turp) Kutz was studied to determine whether isotope or oxidation state differences affect Pu uptake from aqueous medium by algal cells. At equivalent 238 Pu and 239 PU concentrations, even when initial oxidation states differed, accumulations of these isotopes by S.obliquus were not significantly (p>0.05) different. Plutonium accumulation by S.obliquus was log-linear. (author)

  4. Generalized molybdenum oxide surface chemical state XPS determination via informed amorphous sample model

    Energy Technology Data Exchange (ETDEWEB)

    Baltrusaitis, Jonas, E-mail: job314@lehigh.edu [Department of Chemical Engineering, Lehigh University, B336 Iacocca Hall, 111 Research Drive, Bethlehem, PA 18015 (United States); PhotoCatalytic Synthesis group, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, Meander 229, P.O. Box 217, 7500 AE Enschede (Netherlands); Mendoza-Sanchez, Beatriz [CRANN, Chemistry School, Trinity College Dublin, Dublin (Ireland); Fernandez, Vincent [Institut des Matériaux Jean Rouxel, 2 rue de la Houssinière, BP 32229, F-44322 Nantes Cedex 3 (France); Veenstra, Rick [PhotoCatalytic Synthesis group, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, Meander 229, P.O. Box 217, 7500 AE Enschede (Netherlands); Dukstiene, Nijole [Department of Physical and Inorganic Chemistry, Kaunas University of Technology, Radvilenu pl. 19, LT-50254 Kaunas (Lithuania); Roberts, Adam [Kratos Analytical Ltd, Trafford Wharf Road, Wharfside, Manchester, M17 1GP (United Kingdom); Fairley, Neal [Casa Software Ltd, Bay House, 5 Grosvenor Terrace, Teignmouth, Devon TQ14 8NE (United Kingdom)

    2015-01-30

    Highlights: • We analyzed and modeled spectral envelopes of complex molybdenum oxides. • Molybdenum oxide films of varying valence and crystallinity were synthesized. • MoO{sub 3} and MoO{sub 2} line shapes from experimental data were created. • Informed amorphous sample model (IASM) developed. • Amorphous molybdenum oxide XPS envelopes were interpreted. - Abstract: Accurate elemental oxidation state determination for the outer surface of a complex material is of crucial importance in many science and engineering disciplines, including chemistry, fundamental and applied surface science, catalysis, semiconductors and many others. X-ray photoelectron spectroscopy (XPS) is the primary tool used for this purpose. The spectral data obtained, however, is often very complex and can be subject to incorrect interpretation. Unlike traditional XPS spectra fitting procedures using purely synthetic spectral components, here we develop and present an XPS data processing method based on vector analysis that allows creating XPS spectral components by incorporating key information, obtained experimentally. XPS spectral data, obtained from series of molybdenum oxide samples with varying oxidation states and degree of crystallinity, were processed using this method and the corresponding oxidation states present, as well as their relative distribution was elucidated. It was shown that monitoring the evolution of the chemistry and crystal structure of a molybdenum oxide sample due to an invasive X-ray probe could be used to infer solutions to complex spectral envelopes.

  5. SOLID STATE ENERGY CONVERSION ALLIANCE DELPHI SOLID OXIDE FUEL CELL

    Energy Technology Data Exchange (ETDEWEB)

    Steven Shaffer; Sean Kelly; Subhasish Mukerjee; David Schumann; Gail Geiger; Kevin Keegan; John Noetzel; Larry Chick

    2003-12-08

    The objective of Phase I under this project is to develop a 5 kW Solid Oxide Fuel Cell power system for a range of fuels and applications. During Phase I, the following will be accomplished: Develop and demonstrate technology transfer efforts on a 5 kW stationary distributed power generation system that incorporates steam reforming of natural gas with the option of piped-in water (Demonstration System A). Initiate development of a 5 kW system for later mass-market automotive auxiliary power unit application, which will incorporate Catalytic Partial Oxidation (CPO) reforming of gasoline, with anode exhaust gas injected into an ultra-lean burn internal combustion engine. This technical progress report covers work performed by Delphi from January 1, 2003 to June 30, 2003, under Department of Energy Cooperative Agreement DE-FC-02NT41246. This report highlights technical results of the work performed under the following tasks: Task 1 System Design and Integration; Task 2 Solid Oxide Fuel Cell Stack Developments; Task 3 Reformer Developments; Task 4 Development of Balance of Plant (BOP) Components; Task 5 Manufacturing Development (Privately Funded); Task 6 System Fabrication; Task 7 System Testing; Task 8 Program Management; and Task 9 Stack Testing with Coal-Based Reformate.

  6. SOLID STATE ENERGY CONVERSION ALLIANCE DELPHI SOLID OXIDE FUEL CELL

    Energy Technology Data Exchange (ETDEWEB)

    Steven Shaffer; Sean Kelly; Subhasish Mukerjee; David Schumann; Gail Geiger; Kevin Keegan; Larry Chick

    2004-05-07

    The objective of this project is to develop a 5 kW Solid Oxide Fuel Cell power system for a range of fuels and applications. During Phase I, the following will be accomplished: Develop and demonstrate technology transfer efforts on a 5 kW stationary distributed power generation system that incorporates steam reforming of natural gas with the option of piped-in water (Demonstration System A). Initiate development of a 5 kW system for later mass-market automotive auxiliary power unit application, which will incorporate Catalytic Partial Oxidation (CPO) reforming of gasoline, with anode exhaust gas injected into an ultra-lean burn internal combustion engine. This technical progress report covers work performed by Delphi from July 1, 2003 to December 31, 2003, under Department of Energy Cooperative Agreement DE-FC-02NT41246. This report highlights technical results of the work performed under the following tasks: Task 1 System Design and Integration; Task 2 Solid Oxide Fuel Cell Stack Developments; Task 3 Reformer Developments; Task 4 Development of Balance of Plant (BOP) Components; Task 5 Manufacturing Development (Privately Funded); Task 6 System Fabrication; Task 7 System Testing; Task 8 Program Management; Task 9 Stack Testing with Coal-Based Reformate; and Task 10 Technology Transfer from SECA CORE Technology Program. In this reporting period, unless otherwise noted Task 6--System Fabrication and Task 7--System Testing will be reported within Task 1 System Design and Integration. Task 8--Program Management, Task 9--Stack Testing with Coal Based Reformate, and Task 10--Technology Transfer from SECA CORE Technology Program will be reported on in the Executive Summary section of this report.

  7. Reduction Rates for Higher Americium Oxidation States in Nitric Acid

    Energy Technology Data Exchange (ETDEWEB)

    Grimes, Travis Shane [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mincher, Bruce Jay [Idaho National Lab. (INL), Idaho Falls, ID (United States); Schmitt, Nicholas C [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-09-30

    The stability of hexavalent americium was measured using multiple americium concentrations and nitric acid concentrations after contact with the strong oxidant sodium bismuthate. Contrary to our hypotheses Am(VI) was not reduced faster at higher americium concentrations, and the reduction was only zero-order at short time scales. Attempts to model the reduction kinetics using zero order kinetic models showed Am(VI) reduction in nitric acid is more complex than the autoreduction processes reported by others in perchloric acid. The classical zero-order reduction of Am(VI) was found here only for short times on the order of a few hours. We did show that the rate of Am(V) production was less than the rate of Am(VI) reduction, indicating that some Am(VI) undergoes two electron-reduction to Am(IV). We also monitored the Am(VI) reduction in contact with the organic diluent dodecane. A direct comparison of these results with those in the absence of the organic diluent showed the reduction rates for Am(VI) were not statistically different for both systems. Additional americium oxidations conducted in the presence of Ce(IV)/Ce(III) ions showed that Am(VI) is reduced without the typical growth of Am(V) observed in the systems sans Ce ion. This was an interesting result which suggests a potential new reduction/oxidation pathway for Am in the presence of Ce; however, these results were very preliminary, and will require additional experiments to understand the mechanism by which this occurs. Overall, these studies have shown that hexavalent americium is fundamentally stable enough in nitric acid to run a separations process. However, the complicated nature of the reduction pathways based on the system components is far from being rigorously understood.

  8. Approaches to Determining the Oxidation State of Nitrogen and Carbon Atoms in Organic Compounds for High School Students

    Science.gov (United States)

    Jurowski, Kamil; Krzeczkowska, Malgorzata Krystyna; Jurowska, Anna

    2015-01-01

    The concept of oxidation state (or oxidation number) and related issues have always been difficult for students. In addition, there are misunderstandings and obscurities, which can cause improper balancing of the chemical equations (mostly in organic reactions). In particular, these problems are related to determination of the oxidation state of…

  9. Phase Behavior and Equations of State of the Actinide Oxides

    Science.gov (United States)

    Chidester, B.; Pardo, O. S.; Panero, W. R.; Fischer, R. A.; Thompson, E. C.; Heinz, D. L.; Prescher, C.; Prakapenka, V. B.; Campbell, A.

    2017-12-01

    The distribution of the long-lived heat-producing actinide elements U and Th in the deep Earth has important implications for the dynamics of the mantle and possibly the energy budget of Earth's core. The low shear velocities of the Large Low-Shear Velocity Provinces (LLSVPs) on the core-mantle boundary suggests that these regions are at least partially molten and may contain concentrated amounts of the radioactive elements, as well as other large cations such as the rare Earth elements. As such, by exploring the phase behavior of actinide-bearing minerals at extreme conditions, some insight into the mineralogy, formation, and geochemical and geodynamical effects of these regions can be gained. We have performed in situ high-pressure, high-temperature synchrotron X-ray diffraction experiments and calculations on two actinide oxide materials, UO2 and ThO2, to determine their phase behavior at the extreme conditions of the lower mantle. Experiments on ThO2 reached 60 GPa and 2500 K, and experiments on UO2 reached 95 GPa and 2500 K. We find that ThO2 exists in the fluorite-type structure to 20 GPa at high temperatures, at which point it transforms to the high-pressure cotunnite-type structure and remains thus up to 60 GPa. At room temperature, an anomalous expansion of the fluorite structure is observed prior to the transition, and may signal anion sub-lattice disorder. Similarly, UO2 exists in the fluorite-type structure at ambient conditions and up to 28 GPa at high temperatures. Above these pressures, we have observed a previously unidentified phase of UO2 with a tetragonal structure as the lower-temperature phase and the cotunnite-type phase at higher temperatures. Above 78 GPa, UO2 undergoes another transition or possible dissociation into two separate oxide phases. These phase diagrams suggest that the actinides could exist as oxides in solid solution with other analogous phases (e.g. ZrO2) in the cotunnite-type structure throughout much of Earth's lower mantle.

  10. On matrix stabilisation of d- and f-transition metal ions in unstable oxidation states

    Energy Technology Data Exchange (ETDEWEB)

    Kiselev, Yurii M [Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

    2009-01-31

    The state-of-the-art in matrix stabilisation of d- and f-transition metal ions in unstable oxidation states is analysed. Main aspects of this problem concerning the genealogy of appropriate matrix systems are classified. Relevant examples are given and the data that contradict the scheme proposed are discussed. The thermodynamics of the matrix stabilisation effect is considered using the concept of isomorphic miscibility. The influence of defects and non-equilibrium on the matrix stabilisation effect is discussed. The problem of identification of the oxidation states in matrix systems is examined and various types of matrix systems are considered.

  11. On matrix stabilisation of d- and f-transition metal ions in unstable oxidation states

    International Nuclear Information System (INIS)

    Kiselev, Yurii M

    2009-01-01

    The state-of-the-art in matrix stabilisation of d- and f-transition metal ions in unstable oxidation states is analysed. Main aspects of this problem concerning the genealogy of appropriate matrix systems are classified. Relevant examples are given and the data that contradict the scheme proposed are discussed. The thermodynamics of the matrix stabilisation effect is considered using the concept of isomorphic miscibility. The influence of defects and non-equilibrium on the matrix stabilisation effect is discussed. The problem of identification of the oxidation states in matrix systems is examined and various types of matrix systems are considered.

  12. Adsorption properties versus oxidation states of rutile TiO2(110)

    DEFF Research Database (Denmark)

    Martinez, Umberto; Hammer, Bjørk

    2011-01-01

    Using density functional theory we have studied the adsorption properties of different atoms and molecules deposited on a stoichiometric, reduced, and oxidized rutile TiO2(110) surface. Depending on the oxidation state of the surface, electrons can flow from or to the substrate and, therefore...... of the charge flow depends on the oxidation state of the rutile surface and on the adsorption site. Generally, the charging effect leads to more stable complexes. However, the increase in the binding energy of the adsorbates is highly dependent on the electronic states of the surface prior to the adsorption...... event. In this work we have analyzed in details these mechanisms and we have also established a direct correlation between the enhanced binding energy of the adsorbates and the induced gap states...

  13. Microanalysis of iron oxidation state in iron oxides using X Ray Absorption Near Edge Structure (XANES)

    Science.gov (United States)

    Sutton, S. R.; Delaney, J.; Bajt, S.; Rivers, M. L.; Smith, J. V.

    1993-01-01

    An exploratory application of x ray absorption near edge structure (XANES) analysis using the synchrotron x ray microprobe was undertaken to obtain Fe XANES spectra on individual sub-millimeter grains in conventional polished sections. The experiments concentrated on determinations of Fe valence in a suite of iron oxide minerals for which independent estimates of the iron speciation could be made by electron microprobe analysis and x ray diffraction.

  14. The oxidation states of elements in pure and Ca-doped BiCuSeO thermoelectric oxides

    International Nuclear Information System (INIS)

    Hsiao, Chun-Lung; Qi, Xiaoding

    2016-01-01

    Bi 1−x Ca x CuSeO (x = 0–0.3) was synthesized at 650 °C in an air-tight system flowing with pure argon. The Ca doping resulted in an increase in the thermoelectric figure of merit (ZT) as the consequence of increased carrier concentration. X-ray photoelectron spectroscopy (XPS) was carried out to check the oxidation states in Bi 1−x Ca x CuSeO. The results indicated that in addition to the expected Bi 3+ and Cu 1+ , there existed Bi 2+ and Cu 2+ in the undoped BiCuSeO, whereas in the Ca-doped BiCuSeO, Bi 4+ , Cu 3+ and Cu 2+ were observed. The Ca dopant was confirmed to be in the 2+ oxidation state. Two broad peaks centered at 54.22 and 58.59 eV were recorded in the vicinity around the binding energy of Se 3d. The former is often observed in the Se-containing intermetallics while the latter is often found in the Se-containing oxides, indicating that along with the expected Se–Cu bonding, a bonding between Se and O may also exist. Based on the XPS results, the charge compensation mechanisms were proposed for Bi 1−x Ca x CuSeO, which may shed some light on the origins of charge carriers. BiCuSeO based oxides have recently be discovered to have a large ZT comparable to the best alloys currently in use, because of the large Seebeck coefficient and small thermal conductivity. However, their electrical conductivity is lower compared to the best thermoelectrics. This work may provide some hints for the further improvement of ZT in BiCuSeO based oxides. - Graphical abstract: The oxidation states, charge compensation mechanisms, and origins of charge carriers in Bi 1−x Ca x CuSeO thermoelectrics. Display Omitted

  15. Ab initio molecular dynamics simulation of aqueous solution of nitric oxide in different formal oxidation states

    Science.gov (United States)

    Venâncio, Mateus F.; Rocha, Willian R.

    2015-10-01

    Ab initio molecular dynamics simulations were used to investigate the early chemical events involved in the dynamics of nitric oxide (NOrad), nitrosonium cation (NO+) and nitroxide anion (NO-) in aqueous solution. The NO+ ion is very reactive in aqueous solution having a lifetime of ∼4 × 10-13 s, which is shorter than the value of 3 × 10-10 s predicted experimentally. The NO+ reacts generating the nitrous acid as an intermediate and the NO2- ion as the final product. The dynamics of NOrad revealed the reversibly formation of a transient anion radical species HONOrad -.

  16. 99Tc and Re incorporated into metal oxide polyoxometalates: oxidation state stability elucidated by electrochemistry and theory.

    Science.gov (United States)

    McGregor, Donna; Burton-Pye, Benjamin P; Mbomekalle, Israel M; Aparicio, Pablo A; Romo, Susanna; López, Xavier; Poblet, Josep M; Francesconi, Lynn C

    2012-08-20

    The radioactive element technetium-99 ((99)Tc, half-life = 2.1 × 10(5) years, β(-) of 253 keV), is a major byproduct of (235)U fission in the nuclear fuel cycle. (99)Tc is also found in radioactive waste tanks and in the environment at National Lab sites and fuel reprocessing centers. Separation and storage of the long-lived (99)Tc in an appropriate and stable waste-form is an important issue that needs to be addressed. Considering metal oxide solid-state materials as potential storage matrixes for Tc, we are examining the redox speciation of Tc on the molecular level using polyoxometalates (POMs) as models. In this study we investigate the electrochemistry of Tc complexes of the monovacant Wells-Dawson isomers, α(1)-P(2)W(17)O(61)(10-) (α1) and α(2)-P(2)W(17)O(61)(10-) (α2) to identify features of metal oxide materials that can stabilize the immobile Tc(IV) oxidation state accessed from the synthesized Tc(V)O species and to interrogate other possible oxidation states available to Tc within these materials. The experimental results are consistent with density functional theory (DFT) calculations. Electrochemistry of K(7-n)H(n)[Tc(V)O(α(1)-P(2)W(17)O(61))] (Tc(V)O-α1), K(7-n)H(n)[Tc(V)O(α(2)-P(2)W(17)O(61))] (Tc(V)O-α2) and their rhenium analogues as a function of pH show that the Tc-containing derivatives are always more readily reduced than their Re analogues. Both Tc and Re are reduced more readily in the lacunary α1 site as compared to the α2 site. The DFT calculations elucidate that the highest oxidation state attainable for Re is VII while, under the same electrochemistry conditions, the highest oxidation state for Tc is VI. The M(V)→ M(IV) reduction processes for Tc(V)O-α1 are not pH dependent or only slightly pH dependent suggesting that protonation does not accompany reduction of this species unlike the M(V)O-α2 (M = (99)Tc, Re) and Re(V)O-α1 where M(V/IV) reduction process must occur hand in hand with protonation of the terminal M═O to

  17. Carbon oxidation state as a metric for describing the chemistry of atmospheric organic aerosol

    Energy Technology Data Exchange (ETDEWEB)

    Massachusetts Institute of Technology; Kroll, Jesse H.; Donahue, Neil M.; Jimenez, Jose L.; Kessler, Sean H.; Canagaratna, Manjula R.; Wilson, Kevin R.; Altieri, Katye E.; Mazzoleni, Lynn R.; Wozniak, Andrew S.; Bluhm, Hendrik; Mysak, Erin R.; Smith, Jared D.; Kolb, Charles E.; Worsnop, Douglas R.

    2010-11-05

    A detailed understanding of the sources, transformations, and fates of organic species in the environment is crucial because of the central roles that organics play in human health, biogeochemical cycles, and Earth's climate. However, such an understanding is hindered by the immense chemical complexity of environmental mixtures of organics; for example, atmospheric organic aerosol consists of at least thousands of individual compounds, all of which likely evolve chemically over their atmospheric lifetimes. Here we demonstrate the utility of describing organic aerosol (and other complex organic mixtures) in terms of average carbon oxidation state (OSC), a quantity that always increases with oxidation, and is readily measured using state-of-the-art analytical techniques. Field and laboratory measurements of OSC , using several such techniques, constrain the chemical properties of the organics and demonstrate that the formation and evolution of organic aerosol involves simultaneous changes to both carbon oxidation state and carbon number (nC).

  18. Oxidation state analyses of uranium with emphasis on chemical speciation in geological media

    International Nuclear Information System (INIS)

    Ervanne, H.

    2004-01-01

    This thesis focuses on chemical methods suitable for the determination of uranium redox species in geological materials. Nd-coprecipitation method was studied for the determination of uranium oxidation states in ground waters. This method is ideally suited for the separation of uranium oxidation states in the field, which means that problems associated with the instability of U(IV) during transport are avoided. An alternative method, such as ion exchange, is recommended for the analysis of high saline and calcium- and iron-rich ground waters. U(IV)/Utot was 2.8-7.2% in ground waters in oxidizing conditions and 60-93% in anoxic conditions. From thermodynamic model calculations applied to results from anoxic ground waters it was concluded that uranium can act as redox buffer in granitic ground waters. An ion exchange method was developed for the analysis of uranium oxidation states in different solid materials of geological origin. These included uranium minerals, uraniumbearing minerals, fracture coatings and bulk rock. U(IV)/Utot was 50-70% in uraninites, 5.8-8.7% in secondary uranium minerals, 15-49% in different fracture coatings and 64- 77% in samples from deep bedrock. In the uranium-bearing minerals, U(IV)/Utot was 33-43% (allanites), 5.9% (fergusonite) and 93% (monazite). Although the ion exchange method gave reliable results, there is a risk for the conversion of uranium oxidation states during analysis of heterogeneous samples due to the redox reactions that take place in the presence of some iron compounds. This risk was investigated in a study of several common iron-bearing minerals. The risk for conversion of uranium oxidation states can be screened by sample selection and minimized with use of a redox buffer compound such as polyacrylic acid (PAA). In studies of several carboxylic acids, PAA was found to be the most suitable for extending the application of the method. The stability of uranium oxidation states during analysis and the selectivity

  19. Oxidation of extracellular cysteine/cystine redox state in bleomycin-induced lung fibrosis.

    Science.gov (United States)

    Iyer, Smita S; Ramirez, Allan M; Ritzenthaler, Jeffrey D; Torres-Gonzalez, Edilson; Roser-Page, Susanne; Mora, Ana L; Brigham, Kenneth L; Jones, Dean P; Roman, Jesse; Rojas, Mauricio

    2009-01-01

    Several lines of evidence indicate that depletion of glutathione (GSH), a critical thiol antioxidant, is associated with the pathogenesis of idiopathic pulmonary fibrosis (IPF). However, GSH synthesis depends on the amino acid cysteine (Cys), and relatively little is known about the regulation of Cys in fibrosis. Cys and its disulfide, cystine (CySS), constitute the most abundant low-molecular weight thiol/disulfide redox couple in the plasma, and the Cys/CySS redox state (E(h) Cys/CySS) is oxidized in association with age and smoking, known risk factors for IPF. Furthermore, oxidized E(h) Cys/CySS in the culture media of lung fibroblasts stimulates proliferation and expression of transitional matrix components. The present study was undertaken to determine whether bleomycin-induced lung fibrosis is associated with a decrease in Cys and/or an oxidation of the Cys/CySS redox state and to determine whether these changes were associated with changes in E(h) GSH/glutathione disulfide (GSSG). We observed distinct effects on plasma GSH and Cys redox systems during the progression of bleomycin-induced lung injury. Plasma E(h) GSH/GSSG was selectively oxidized during the proinflammatory phase, whereas oxidation of E(h) Cys/CySS occurred at the fibrotic phase. In the epithelial lining fluid, oxidation of E(h) Cys/CySS was due to decreased food intake. Thus the data show that decreased precursor availability and enhanced oxidation of Cys each contribute to the oxidation of extracellular Cys/CySS redox state in bleomycin-induced lung fibrosis.

  20. DetOx: a program for determining anomalous scattering factors of mixed-oxidation-state species.

    Science.gov (United States)

    Sutton, Karim J; Barnett, Sarah A; Christensen, Kirsten E; Nowell, Harriott; Thompson, Amber L; Allan, David R; Cooper, Richard I

    2013-01-01

    Overlapping absorption edges will occur when an element is present in multiple oxidation states within a material. DetOx is a program for partitioning overlapping X-ray absorption spectra into contributions from individual atomic species and computing the dependence of the anomalous scattering factors on X-ray energy. It is demonstrated how these results can be used in combination with X-ray diffraction data to determine the oxidation state of ions at specific sites in a mixed-valance material, GaCl(2).

  1. Studies of surface states in zinc oxide nanopowders

    Science.gov (United States)

    Peters, Raul Mugabe

    The surface of ZnO semiconductor nanosystems is a key performance-defining factor in numerous applications. In this work we present experimental results for the surface defect-related properties of ZnO nanoscale systems. Surface photovoltage spectroscopy was used to determine the defect level energies within the band gap, the conduction vs. valence band nature of the defect-related transitions, and to probe key dynamic parameters of the surface on a number of commercially available ZnO nanopowders. In our experimental setup, surface photovoltage characterization is conducted in high vacuum in tandem with in situ oxygen remote plasma treatments. Surface photovoltage investigations of the as-received and plasma-processed samples revealed a number of common spectral features related to surface states. Furthermore, we observed significant plasma-induced changes in the surface defect properties. Ex situ positron annihilation and photoluminescence measurements were performed on the studied samples and correlated with surface photovoltage results. The average positron lifetimes were found to be substantially longer than in a bulk single crystalline sample, which is consistent with the model of grains with defect-rich surface and subsurface layers. Compression of the powders into pellets yielded reduction of the average positron lifetimes. Surface photovoltage, positron annihilation, and photoluminescence spectra consistently showed sample-to-sample differences due to the variation in the overall quality of the nanopowders, which partially obscures observation of the scaling effects. However, the results demonstrated that our approach is efficient in detecting specific surface states in nanoscale ZnO specimens and in elucidating their nature.

  2. Conformational Toggling of Yeast Iso-1-Cytochrome c in the Oxidized and Reduced States

    Science.gov (United States)

    Yang, Zhongzheng; Zhu, Jing; Ying, Tianlei; Jiang, Xianwang; Zhang, Xu; Wu, Houming; Liu, Maili; Tan, Xiangshi; Cao, Chunyang; Huang, Zhong-Xian

    2011-01-01

    To convert cyt c into a peroxidase-like metalloenzyme, the P71H mutant was designed to introduce a distal histidine. Unexpectedly, its peroxidase activity was found even lower than that of the native, and that the axial ligation of heme iron was changed to His71/His18 in the oxidized state, while to Met80/His18 in the reduced state, characterized by UV-visible, circular dichroism, and resonance Raman spectroscopy. To further probe the functional importance of Pro71 in oxidation state dependent conformational changes occurred in cyt c, the solution structures of P71H mutant in both oxidation states were determined. The structures indicate that the half molecule of cyt c (aa 50–102) presents a kind of “zigzag riveting ruler” structure, residues at certain positions of this region such as Pro71, Lys73 can move a big distance by altering the tertiary structure while maintaining the secondary structures. This finding provides a molecular insight into conformational toggling in different oxidation states of cyt c that is principle significance to its biological functions in electron transfer and apoptosis. Structural analysis also reveals that Pro71 functions as a key hydrophobic patch in the folding of the polypeptide of the region (aa 50–102), to prevent heme pocket from the solvent. PMID:22087268

  3. The Impact of Environmental Factors in Influencing Epigenetics Related to Oxidative States in the Cardiovascular System

    Directory of Open Access Journals (Sweden)

    Francesco Angelini

    2017-01-01

    Full Text Available Oxidative states exert a significant influence on a wide range of biological and molecular processes and functions. When their balance is shifted towards enhanced amounts of free radicals, pathological phenomena can occur, as the generation of reactive oxygen species (ROS in tissue microenvironment or in the systemic circulation can be detrimental. Epidemic chronic diseases of western societies, such as cardiovascular disease, obesity, and diabetes correlate with the imbalance of redox homeostasis. Current advances in our understanding of epigenetics have revealed a parallel scenario showing the influence of oxidative stress as a major regulator of epigenetic gene regulation via modification of DNA methylation, histones, and microRNAs. This has provided both the biological link and a potential molecular explanation between oxidative stress and cardiovascular/metabolic phenomena. Accordingly, in this review, we will provide current insights on the physiological and pathological impact of changes in oxidative states on cardiovascular disorders, by specifically focusing on the influence of epigenetic regulation. A special emphasis will highlight the effect on epigenetic regulation of human’s current life habits, external and environmental factors, including food intake, tobacco, air pollution, and antioxidant-based approaches. Additionally, the strategy to quantify oxidative states in humans in order to determine which biological marker could best match a subject’s profile will be discussed.

  4. Oxidation states of Fe in LaNi1-xFexO3

    International Nuclear Information System (INIS)

    Goeta, A.E.; Falcon, H.; Carbonio, R.

    1994-01-01

    The distribution of oxidation states in perovskites of the type LaA 1-x B x O 3 (A and B transition metal ions) can be ''tailored'' by x variation. In particular, in LaNiO 3 it has been shown that Fe substitution for Ni foces some Ni 3+ into Ni 2+ , while some Fe 3+ changes into the unusual Fe 4+ state. In addition, the existence of mixed oxidation states of Fe and/or Ni in LaNi 1-x Fe x O 3 has been related to its catalytic activity in hydrogen peroxide decomposition. The Fe 4+ population, obtained using Moessbauer spectroscopy, was found to be constant for all the analyzed annealing temperatures for x = 0.25 concentration, where the isomer shift difference for both states is the highest and the catalytic activity is maximum. (orig.)

  5. Facile solid-state synthesis of oxidation-resistant metal nanoparticles at ambient conditions

    Science.gov (United States)

    Lee, Kyu Hyung; Jung, Hyuk Joon; Lee, Ju Hee; Kim, Kyungtae; Lee, Byeongno; Nam, Dohyun; Kim, Chung Man; Jung, Myung-Hwa; Hur, Nam Hwi

    2018-05-01

    A simple and scalable method for the synthesis of metal nanoparticles in the solid-state was developed, which can produce nanoparticles in the absence of solvents. Nanoparticles of coinage metals were synthesized by grinding solid hydrazine and the metal precursors in their acetates and oxides at 25 °C. The silver and gold acetates converted completely within 6 min into Ag and Au nanoparticles, respectively, while complete conversion of the copper acetate to the Cu sub-micrometer particles took about 2 h. Metal oxide precursors were also converted into metal nanoparticles by grinding alone. The resulting particles exhibit distinctive crystalline lattice fringes, indicating the formation of highly crystalline phases. The Cu sub-micrometer particles are better resistant to oxidation and exhibit higher conductivity compared to conventional Cu nanoparticles. This solid-state method was also applied for the synthesis of platinum group metals and intermetallic Cu3Au, which can be further extended to synthesize other metal nanoparticles.

  6. How different oxidation states of crystalline myoglobin are influenced by X-rays.

    Science.gov (United States)

    Hersleth, Hans-Petter; Andersson, K Kristoffer

    2011-06-01

    X-ray induced radiation damage of protein crystals is well known to occur even at cryogenic temperatures. Redox active sites like metal sites seem especially vulnerable for these radiation-induced reductions. It is essential to know correctly the oxidation state of metal sites in protein crystal structures to be able to interpret the structure-function relation. Through previous structural studies, we have tried to characterise and understand the reactions between myoglobin and peroxides. These reaction intermediates are relevant because myoglobin is proposed to take part as scavenger of reactive oxygen species during oxidative stress, and because these intermediates are similar among the haem peroxidases and oxygenases. We have in our previous studies shown that these different myoglobin states are influenced by the X-rays used. In this study, we have in detail investigated the impact that X-rays have on these different oxidation states of myoglobin. An underlying goal has been to find a way to be able to determine mostly unreduced states. We have by using single-crystal light absorption spectroscopy found that the different oxidation states of myoglobin are to a different extent influenced by the X-rays (e.g. ferric Fe(III) myoglobin is faster reduced than ferryl Fe(IV)═O myoglobin). We observe that the higher oxidation states are not reduced to normal ferrous Fe(II) or ferric Fe(III) states, but end up in some intermediate and possibly artificial states. For ferric myoglobin, it seems that annealing of the radiation-induced/reduced state can reversibly more or less give the starting point (ferric myoglobin). Both scavengers and different dose-rates might influence to which extent the different states are affected by the X-rays. Our study shows that it is essential to do a time/dose monitoring of the influence X-rays have on each specific redox-state with spectroscopic techniques like single-crystal light absorption spectroscopy. This will determine to which

  7. Templated electrodeposition of Ag7NO11 nanowires with very high oxidation states of silver

    NARCIS (Netherlands)

    Rodijk, E.J.B.; Maijenburg, A.W.; Maas, M.G.; Blank, David H.A.; ten Elshof, Johan E.

    2011-01-01

    The templated electrodeposition of 200 nm diameter nanowires of the argentic oxynitrate Ag(Ag3O4)2NO3 phase is reported. Their high surface-to-volume ratio and the high average oxidation state of Ag make these wires promising candidates for nanoscale redox processes in which both a high volumetric

  8. Investigation of the oxidation states of Pu isotopes in a hydrochloric acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Lee, M.H. [Nuclear Chemistry Research Division, Korea Atomic Energy Research Institute, P. O. Box 105, Yuseong, Daejeon 305-353 (Korea, Republic of)], E-mail: mhlee@kaeri.re.kr; Kim, J.Y.; Kim, W.H.; Jung, E.C.; Jee, K.Y. [Nuclear Chemistry Research Division, Korea Atomic Energy Research Institute, P. O. Box 105, Yuseong, Daejeon 305-353 (Korea, Republic of)

    2008-12-15

    The characteristics of the oxidation states of Pu in a hydrochloric acid solution were investigated and the results were applied to a separating of Pu isotopes from IAEA reference soils. The oxidation states of Pu(III) and Pu(IV) were prepared by adding hydroxylamine hydrochloride and sodium nitrite to a Pu stock solution, respectively. Also, the oxidation state of Pu(VI) was adjusted with concentrated HNO{sub 3} and HClO{sub 4}. The stability of the various oxidation states of plutonium in a HCl solution with elapsed time after preparation were found to be in the following order: Pu(III){approx}Pu(VI)>Pu(IV)>Pu(V). The chemical recoveries of Pu(IV) in a 9 M HCl solution with an anion exchange resin were similar to those of Pu(VI). This method for the determination of Pu isotopes with an anion exchange resin in a 9 M HCl medium was applied to IAEA reference soils where the activity concentrations of {sup 239,240}Pu and {sup 238}Pu in IAEA-375 and IAEA-326 were consistent with the reference values reported by the IAEA.

  9. Teaching the Properties of Chromium's Oxidation States with a Case Study Method

    Science.gov (United States)

    Ozdilek, Zehra

    2015-01-01

    The purpose of this study was to investigate how a mixed-method case study affects pre-service science teachers' awareness of hexavalent chromium pollution and content knowledge about the properties of chromium's different oxidation states. The study was conducted in Turkey with 55 sophomores during the fall semester of 2013-2014. The students…

  10. The Effect of Precursor Ligands and Oxidation State in the Synthesis of Bimetallic Nano-Alloys

    KAUST Repository

    LaGrow, Alec P.; Knudsen, Kristian; AlYami, Noktan; Anjum, Dalaver H.; Bakr, Osman

    2015-01-01

    of variables on the characteristics of bimetallic nanomaterials are not completely understood. In this study, we used a continuous-flow synthetic strategy to explore the effects of the ligands and the oxidation state of a metal precursor in a shape

  11. Regulation of Ca2+ release from mitochondria by the oxidation-reduction state of pyridine nucleotides

    Science.gov (United States)

    Lehninger, Albert L.; Vercesi, Anibal; Bababunmi, Enitan A.

    1978-01-01

    Mitochondria from normal rat liver and heart, and also Ehrlich tumor cells, respiring on succinate as energy source in the presence of rotenone (to prevent net electron flow to oxygen from the endogenous pyridine nucleotides), rapidly take up Ca2+ and retain it so long as the pyridine nucleotides are kept in the reduced state. When acetoacetate is added to bring the pyridine nucleotides into a more oxidized state, Ca2+ is released to the medium. A subsequent addition of a reductant of the pyridine nucleotides such as β-hydroxybutyrate, glutamate, or isocitrate causes reuptake of the released Ca2+. Successive cycles of Ca2+ release and uptake can be induced by shifting the redox state of the pyridine nucleotides to more oxidized and more reduced states, respectively. Similar observations were made when succinate oxidation was replaced as energy source by ascorbate oxidation or by the hydrolysis of ATP. These and other observations form the basis of a hypothesis for feedback regulation of Ca2+-dependent substrate- or energy-mobilizing enzymatic reactions by the uptake or release of mitochondrial Ca2+, mediated by the cytosolic phosphate potential and the ATP-dependent reduction of mitochondrial pyridine nucleotides by reversal of electron transport. Images PMID:25436

  12. Measurements of the oxidation state and concentration of plutonium in interstitial waters of the Irish Sea

    International Nuclear Information System (INIS)

    Nelson, D.M.; Lovett, M.B.

    1980-01-01

    The question of plutonium movement in interstitial waters resulting from diffusion along concentration gradients or from advective flow is addressed. The results of measurements of both the concentration and the oxidation state of plutonium in interstitial water collected from sediments near the Windscale discharge, in the solid phases of these sediments and in seawater and suspended solids collected at the coring locations are discussed

  13. Heterogeneous Oxidation of Atmospheric Organic Aerosol: Kinetics of Changes to the Amount and Oxidation State of Particle-Phase Organic Carbon.

    Science.gov (United States)

    Kroll, Jesse H; Lim, Christopher Y; Kessler, Sean H; Wilson, Kevin R

    2015-11-05

    Atmospheric oxidation reactions are known to affect the chemical composition of organic aerosol (OA) particles over timescales of several days, but the details of such oxidative aging reactions are poorly understood. In this study we examine the rates and products of a key class of aging reaction, the heterogeneous oxidation of particle-phase organic species by the gas-phase hydroxyl radical (OH). We compile and reanalyze a number of previous studies from our laboratories involving the oxidation of single-component organic particles. All kinetic and product data are described on a common basis, enabling a straightforward comparison among different chemical systems and experimental conditions. Oxidation chemistry is described in terms of changes to key ensemble properties of the OA, rather than to its detailed molecular composition, focusing on two quantities in particular, the amount and the oxidation state of the particle-phase carbon. Heterogeneous oxidation increases the oxidation state of particulate carbon, with the rate of increase determined by the detailed chemical mechanism. At the same time, the amount of particle-phase carbon decreases with oxidation, due to fragmentation (C-C scission) reactions that form small, volatile products that escape to the gas phase. In contrast to the oxidation state increase, the rate of carbon loss is nearly uniform among most systems studied. Extrapolation of these results to atmospheric conditions indicates that heterogeneous oxidation can have a substantial effect on the amount and composition of atmospheric OA over timescales of several days, a prediction that is broadly in line with available measurements of OA evolution over such long timescales. In particular, 3-13% of particle-phase carbon is lost to the gas phase after one week of heterogeneous oxidation. Our results indicate that oxidative aging represents an important sink for particulate organic carbon, and more generally that fragmentation reactions play a major

  14. Influence of microorganisms on the oxidation state distribution of multivalent actinides under anoxic conditions

    International Nuclear Information System (INIS)

    Reed, Donald Timothy; Borkowski, Marian; Lucchini, Jean-Francois; Ams, David; Richmann, M.K.; Khaing, H.; Swanson, J.S.

    2010-01-01

    The fate and potential mobility of multivalent actinides in the subsurface is receiving increased attention as the DOE looks to cleanup the many legacy nuclear waste sites and associated subsurface contamination. Plutonium, uranium and neptunium are the near-surface multivalent contaminants of concern and are also key contaminants for the deep geologic disposal of nuclear waste. Their mobility is highly dependent on their redox distribution at their contamination source as well as along their potential migration pathways. This redox distribution is often controlled, especially in the near-surface where organic/inorganic contaminants often coexist, by the direct and indirect effects of microbial activity. Under anoxic conditions, indirect and direct bioreduction mechanisms exist that promote the prevalence of lower-valent species for multivalent actinides. Oxidation-state-specific biosorption is also an important consideration for long-term migration and can influence oxidation state distribution. Results of ongoing studies to explore and establish the oxidation-state specific interactions of soil bacteria (metal reducers and sulfate reducers) as well as halo-tolerant bacteria and Archaea for uranium, neptunium and plutonium will be presented. Enzymatic reduction is a key process in the bioreduction of plutonium and uranium, but co-enzymatic processes predominate in neptunium systems. Strong sorptive interactions can occur for most actinide oxidation states but are likely a factor in the stabilization of lower-valent species when more than one oxidation state can persist under anaerobic microbiologically-active conditions. These results for microbiologically active systems are interpreted in the context of their overall importance in defining the potential migration of multivalent actinides in the subsurface.

  15. Origin of deep subgap states in amorphous indium gallium zinc oxide: Chemically disordered coordination of oxygen

    International Nuclear Information System (INIS)

    Sallis, S.; Williams, D. S.; Butler, K. T.; Walsh, A.; Quackenbush, N. F.; Junda, M.; Podraza, N. J.; Fischer, D. A.; Woicik, J. C.; White, B. E.; Piper, L. F. J.

    2014-01-01

    The origin of the deep subgap states in amorphous indium gallium zinc oxide (a-IGZO), whether intrinsic to the amorphous structure or not, has serious implications for the development of p-type transparent amorphous oxide semiconductors. We report that the deep subgap feature in a-IGZO originates from local variations in the oxygen coordination and not from oxygen vacancies. This is shown by the positive correlation between oxygen composition and subgap intensity as observed with X-ray photoelectron spectroscopy. We also demonstrate that the subgap feature is not intrinsic to the amorphous phase because the deep subgap feature can be removed by low-temperature annealing in a reducing environment. Atomistic calculations of a-IGZO reveal that the subgap state originates from certain oxygen environments associated with the disorder. Specifically, the subgap states originate from oxygen environments with a lower coordination number and/or a larger metal-oxygen separation.

  16. Origin of deep subgap states in amorphous indium gallium zinc oxide: Chemically disordered coordination of oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Sallis, S.; Williams, D. S. [Materials Science and Engineering, Binghamton University, Binghamton, New York 13902 (United States); Butler, K. T.; Walsh, A. [Center for Sustainable Technologies and Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Quackenbush, N. F. [Department of Physics, Applied Physics, and Astronomy, Binghamton University, Binghamton, New York 13902 (United States); Junda, M.; Podraza, N. J. [Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606 (United States); Fischer, D. A.; Woicik, J. C. [Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); White, B. E.; Piper, L. F. J., E-mail: lpiper@binghamton.edu [Department of Physics, Applied Physics, and Astronomy, Binghamton University, Binghamton, New York 13902 (United States); Materials Science and Engineering, Binghamton University, Binghamton, New York 13902 (United States)

    2014-06-09

    The origin of the deep subgap states in amorphous indium gallium zinc oxide (a-IGZO), whether intrinsic to the amorphous structure or not, has serious implications for the development of p-type transparent amorphous oxide semiconductors. We report that the deep subgap feature in a-IGZO originates from local variations in the oxygen coordination and not from oxygen vacancies. This is shown by the positive correlation between oxygen composition and subgap intensity as observed with X-ray photoelectron spectroscopy. We also demonstrate that the subgap feature is not intrinsic to the amorphous phase because the deep subgap feature can be removed by low-temperature annealing in a reducing environment. Atomistic calculations of a-IGZO reveal that the subgap state originates from certain oxygen environments associated with the disorder. Specifically, the subgap states originate from oxygen environments with a lower coordination number and/or a larger metal-oxygen separation.

  17. Structural oxidation state studies of the manganese cluster in the oxygen evolving complex of photosystem II

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Wenchuan [Univ. of California, Berkeley, CA (United States)

    1994-11-01

    X-ray absorption spectroscopy (XAS) was performed on Photosystem II (PSII)-enriched membranes prepared from spinach to explore: (1) the correlation between structure and magnetic spin state of the Mn cluster in the oxygen evolving complex (OEC) in the S2 state; and (2) the oxidation state changes of the Mn cluster in the flash-induced S-states. The structure of the Mn cluster in the S2 state with the g~4 electron paramagnetic resonance (EPR) signal (S2-g4 state) was compared with that in the S2 state with multiline signal (S2-MLS state) and the S1 state. The S2-g4 state has a higher XAS inflection point energy than that of the S1 state, indicating the oxidation of Mn in the advance from the S1 to the S2-g4 state. Differences in the edge shape and in the extended X-ray absorption fine structure (EXAFS) show that the structure of the Mn cluster in the S2-g4 state is different from that in the S2-MLS or the S1 state. In the S2-g4 state, the second shell of backscatterers from the Mn absorber contains two Mn-Mn distances of 2.73 Å and 2.85 Å. Very little distance disorder exists in the second shell of the S1 or S2-MLS states. The third shell of the S2-g4 state at about 3.3 Å also contains increased heterogeneity relative to that of the S2-MLS or the S1 state. Various S-states were prepared at room-temperature by saturating, single-turnover flashes. The flash-dependent oscillation in the amplitude of the MLS was used to characterize the S-state composition and to construct "pure" S-state Mn K-edge spectra. The edge position shifts to higher energy by 1.8 eV upon the S1 → S2 transition.

  18. Method of isolation of traces of americium by using the +6 oxidation state properties

    International Nuclear Information System (INIS)

    Kwinta, Jean; Michel, Jean-Jacques

    1969-05-01

    The authors present a method to separate traces of americium from a solution containing fission products and actinides. This method comprises the following steps: firstly, the oxidation of americium at the +6 state by ammonium persulfate and carrying over of actinides and III and IV lanthanides by lanthanum fluoride; secondly, the reduction by hydrazine of the oxidized americium and carrying over of the reduced americium by lutetium fluoride; and thirdly, the americium-lutetium separation by selective extractions either with di 2 ethyl hexyl phosphoric acid, or by fractionated elution on an anionic resin column by a mixture of nitric acid and methanol [fr

  19. Extracellular redox state: refining the definition of oxidative stress in aging.

    Science.gov (United States)

    Jones, Dean P

    2006-01-01

    Oxidative stress in aging can result from an imbalance of prooxidants and antioxidants with excessive, destructive free radical chemistry. Thiol systems are important in the control of these processes, both by protecting against damage and serving in redox signaling mechanisms to sense danger and repair the damage. Studies by a number of research groups in collaboration with the Emory Clinical Biomarkers Laboratory show that the redox state of the central tissue antioxidant, glutathione (GSH), can be measured in human plasma and provides a quantitative systemic indicator of oxidative stress. Plasma GSH/GSSG redox in humans becomes oxidized with age, in response to chemotherapy, as a consequence of cigarette smoking, and in association with common age-related diseases (e.g., type 2 diabetes, cardiovascular disease). However, the GSH/GSSG redox is not equilibrated with the larger plasma cysteine/cystine (Cys/CySS) pool, and the Cys/CySS redox varies with age in a pattern that is distinct from that of GSH/GSSG redox. Furthermore, in vitro studies show that variation in Cys/CySS redox over the range found in vivo affects signaling pathways, which control cell proliferation and oxidant-induced apoptosis. The results point to the conclusion that free radical scavenging antioxidants are of increased importance when thiol/disulfide redox states are oxidized. Because thiol/disulfide redox states, per se, function in redox signaling and control as well as antioxidant protection, GSH/GSSG and Cys/CySS redox states may provide central parameters to link environmental influences and progression of changes associated with aging.

  20. General regularity of the oxidation potential variations and high oxidation states in the second half of the actinide series

    International Nuclear Information System (INIS)

    Spitsyn, V.I.; Vokhmin, V.G.; Ionova, G.V.; Pershina, V.G.

    1984-01-01

    Oxidation potentials (OP) PHI(4/3), PHI(5/3), PHI(6/3), PHI(5/4) and PHI(6/5) are calculated for the members of the actinide series. A semiemperic relation combining OP with explicit terms for ground level energies of actinide ions in Russell-Saunders approximation as well as known values of formal OP relative to the normal hydrogen electrode potential are used as an extrapolation function. It is shown that an increase of PHI(4/3) OP which occurs after Bsub(k) explains a low stability of the oxidation state 4 in solutions for actinides of the second half of the series. PHI(5/3) and PHI(5/4) OP in the section starting with Cm have the minimum at Cf. PHI(6/3) OP for Cm, Bk, Cf and Es are practically the same but for Cm, Bk and Es they are smaller than PHI(5/3) OP. A principle possibility of Bk(6), Cf(6) and Es(6) preparation is shown

  1. In situ oxidation state profiling of nickel hexacyanoferrate derivatized electrodes using line-imaging Raman spectroscopy and multivariate calibration

    International Nuclear Information System (INIS)

    Haight, S.M.; Schwartz, D.T.

    1999-01-01

    Metal hexacyanoferrate compounds show promise as electrochemically switchable ion exchange materials for use in the cleanup of radioactive wastes such as those found in storage basins and underground tanks at the Department of Energy's Hanford Nuclear Reservation. Reported is the use of line-imaging Raman spectroscopy for the in situ determination of oxidation state profiles in nickel hexacyanoferrate derivatized electrodes under potential control in an electrochemical cell. Line-imaging Raman spectroscopy is used to collect 256 contiguous Raman spectra every ∼5 microm from thin films (ca. 80 nm) formed by electrochemical derivatization of nickel electrodes. The cyanide stretching region of the Raman spectrum of the film is shown to be sensitive to iron oxidation state and is modeled by both univariate and multivariate correlations. Although both correlations fit the calibration set well, the multivariate (principle component regression or PCR) model's predictions of oxidation state are less sensitive to noise in the spectrum, yielding a much smoother oxidation state profile than the univariate model. Oxidation state profiles with spatial resolution of approximately 5 microm are shown for a nickel hexacyanoferrate derivatized electrode in reduced, intermediate, and oxidized states. In situ oxidation state profiles indicate that the 647.1 nm laser illumination photo-oxidizes the derivatized electrodes. This observation is confirmed using photoelectrochemical methods

  2. Coupled interactions between volatile activity and Fe oxidation state during arc crustal processes

    Science.gov (United States)

    Humphreys, Madeleine C.S.; Brooker, R; Fraser, D.C.; Burgisser, A; Mangan, Margaret T.; McCammon, C

    2015-01-01

    Arc magmas erupted at the Earth’s surface are commonly more oxidized than those produced at mid-ocean ridges. Possible explanations for this high oxidation state are that the transfer of fluids during the subduction process results in direct oxidation of the sub-arc mantle wedge, or that oxidation is caused by the effect of later crustal processes, including protracted fractionation and degassing of volatile-rich magmas. This study sets out to investigate the effect of disequilibrium crustal processes that may involve coupled changes in H2O content and Fe oxidation state, by examining the degassing and hydration of sulphur-free rhyolites. We show that experimentally hydrated melts record strong increases in Fe3+/∑Fe with increasing H2O concentration as a result of changes in water activity. This is relevant for the passage of H2O-undersaturated melts from the deep crust towards shallow crustal storage regions, and raises the possibility that vertical variations in fO2 might develop within arc crust. Conversely, degassing experiments produce an increase in Fe3+/∑Fe with decreasing H2O concentration. In this case the oxidation is explained by loss of H2 as well as H2O into bubbles during decompression, consistent with thermodynamic modelling, and is relevant for magmas undergoing shallow degassing en route to the surface. We discuss these results in the context of the possible controls on fO2 during the generation, storage and ascent of magmas in arc settings, in particular considering the timescales of equilibration relative to observation as this affects the quality of the petrological record of magmatic fO2.

  3. Radiation oxidation of polypropylene: A solid-state 13C NMR study using selective isotopic labeling

    International Nuclear Information System (INIS)

    Mowery, Daniel M.; Assink, Roger A.; Derzon, Dora K.; Klamo, Sara B.; Bernstein, Robert; Clough, Roger L.

    2007-01-01

    Polypropylene samples, in which the three different carbon atoms along the chain were selectively labeled with carbon-13, were subjected to radiation under inert and air atmospheres, and to post-irradiation exposure in air at various temperatures. By using solid-state 13 C NMR measurements at room temperature, we have been able to identify and quantify the oxidation products. The isotopic labeling provides insight into chemical reaction mechanisms, since oxidation products can be traced back to their positions of origin on the macromolecule. The major products include peroxides and alcohols, both formed at tertiary carbon sites along the chain. Other products include methyl ketones, acids, esters, peresters, and hemiketals formed from reaction at the tertiary carbon, together with in-chain ketones and esters from reaction at the secondary chain carbon. No evidence is found of products arising from reactions at the methyl side chain. Significant temperature-dependent differences are apparent; for example much higher yields of chain-end methyl ketones, which are the indicator product of chain scission, are generated for both elevated temperature irradiation and for post-irradiation treatment at elevated temperatures. Time-dependent plots of yields of the various oxidation products have been obtained under a wide range of conditions, including the post-irradiation oxidation of a sample at room temperature in air that has been monitored for 2 years. Radiation-oxidation products of polypropylene are contrasted to products measured for 13 C-labeled polyethylene in an earlier investigation: the peroxides formed in irradiated polypropylene are remarkably longer lived, the non-peroxidic products are significantly different, and the overall ratios of oxidation products in polypropylene change relatively little as a function of the extent of oxidation

  4. Microbial utilization of low molecular weight organic substrates in soil depends on their carbon oxidation state

    Science.gov (United States)

    Gunina, Anna; Smith, Andrew; Jones, Davey; Kuzyakov, Yakov

    2017-04-01

    Removal of low molecular weight organic substances (LMWOS), originating from plants and microorganisms, from soil solution is regulated by microbial uptake. In addition to the concentration of LMWOS in soil solution, the chemical properties of each substance (e.g. C oxidation state, number of C atoms, number of -COOH groups) can affect their uptake and subsequent partitioning of C within the soil microbial community. The aim of this study was to trace the initial fate of three dominant classes of LMWOS in soil (sugars, carboxylic and amino acids), including their removal from solution and utilization by microorganisms, and to reveal the effect of substance chemical properties on these processes. Soil solution, spiked at natural abundance levels with 14C-labelled glucose, fructose, malate, succinate, formate, alanine or glycine, was added to the soil and 14C was traced in the dissolved organic carbon (DOC), CO2, cytosol and soil organic carbon (SOC) over 24 hours. The half-life time of all LMWOS in the DOC (T1 /2-solution) varied between 0.6-5.0 min showing extremely fast initial uptake of LMWOS. The T1 /2-solution of substances was dependent on C oxidation state, indicating that less oxidized organic substances (with C oxidation state "0") were retained longer in soil solution than oxidized substances. The LMWOS-C T1 /2-fast, characterizing the half-life time of 14C in the fast mineralization pool, ranged between 30 and 80 min, with the T1 /2-fast of carboxylic acids (malic acid) being the fastest and the T1 /2-fast of amino acids (glycine) being the slowest. An absence of correlation between T1 /2-fast and either C oxidation state, number of C atoms, or number of -COOH groups suggests that intercellular metabolic pathways are more important for LMWOS transformation in soil than their basic chemical properties. The CO2 release during LMWOS mineralization accounted for 20-90% of 14C applied. Mineralization of LMWOS was the least for sugars and the greatest for

  5. Influence of steam generator surface state on corrosion and oxide formation

    International Nuclear Information System (INIS)

    Mazenc, Arnaud; Leclercq, Stephanie; Seyeux, Antoine; Galtayries, Anouk; Marcus, Philippe

    2012-09-01

    The corrosion and release of nickel-based alloy Steam Generator tubes are partly due to their surface state. Among the most important parameters influencing the corrosion, the effect of grain size and the effect of grain crystallographic orientation have been chosen to be studied. The aim of this study is to determine how these parameters have an impact on the corrosion of Steam Generator tubes. Thermal treatments (700 deg. C and 1050 deg. C) have been performed on several samples in Alloy 690 to obtain homogeneous grain sizes, varying from 25 μm to 110 μm. Two samples have been oxidised for four days in a recirculating autoclave, reproducing primary conditions. The changes of oxide composition and thickness were examined by ToF-SIMS on samples exposed to primary water conditions. The intensity profiles versus thicknesses of characteristic oxide anions, such as CrO - , NiO - or FeO - enable us to evaluate the effect of grain size and crystallographic orientation on the formation of an enriched inner chromium layer. As regards to the grain size, there was no effect on the growth, but smaller grains led to a chromium-rich oxide layer. The effect of crystallographic orientation was observed on the oxidation kinetics and the composition of oxide scales. (authors)

  6. Characterization of Interface State in Silicon Carbide Metal Oxide Semiconductor Capacitors

    Science.gov (United States)

    Kao, Wei-Chieh

    Silicon carbide (SiC) has always been considered as an excellent material for high temperature and high power devices. Since SiC is the only compound semiconductor whose native oxide is silicon dioxide (SiO2), it puts SiC in a unique position. Although SiC metal oxide semiconductor (MOS) technology has made significant progress in recent years, there are still a number of issues to be overcome before more commercial SiC devices can enter the market. The prevailing issues surrounding SiC MOSFET devices are the low channel mobility, the low quality of the oxide layer and the high interface state density at the SiC/SiO2 interface. Consequently, there is a need for research to be performed in order to have a better understanding of the factors causing the poor SiC/SiO2 interface properties. In this work, we investigated the generation lifetime in SiC materials by using the pulsed metal oxide semiconductor (MOS) capacitor method and measured the interface state density distribution at the SiC/SiO2 interface by using the conductance measurement and the high-low frequency capacitance technique. These measurement techniques have been performed on n-type and p-type SiC MOS capacitors. In the course of our investigation, we observed fast interface states at semiconductor-dielectric interfaces in SiC MOS capacitors that underwent three different interface passivation processes, such states were detected in the nitrided samples but not observed in PSG-passivated samples. This result indicate that the lack of fast states at PSG-passivated interface is one of the main reasons for higher channel mobility in PSG MOSFETs. In addition, the effect of mobile ions in the oxide on the response time of interface states has been investigated. In the last chapter we propose additional methods of investigation that can help elucidate the origin of the particular interface states, enabling a more complete understanding of the SiC/SiO2 material system.

  7. A magnetic route to measure the average oxidation state of mixed-valent manganese in manganese oxide octahedral molecular sieves (OMS).

    Science.gov (United States)

    Shen, Xiong-Fei; Ding, Yun-Shuang; Liu, Jia; Han, Zhao-Hui; Budnick, Joseph I; Hines, William A; Suib, Steven L

    2005-05-04

    A magnetic route has been applied for measurement of the average oxidation state (AOS) of mixed-valent manganese in manganese oxide octahedral molecular sieves (OMS). The method gives AOS measurement results in good agreement with titration methods. A maximum analysis deviation error of +/-7% is obtained from 10 sample measurements. The magnetic method is able to (1) confirm the presence of mixed-valent manganese and (2) evaluate AOS and the spin states of d electrons of both single oxidation state and mixed-valent state Mn in manganese oxides. In addition, the magnetic method may be extended to (1) determine AOS of Mn in manganese oxide OMS with dopant "diamagnetic" ions, such as reducible V5+ (3d0) ions, which is inappropriate for the titration method due to interference of redox reactions between these dopant ions and titration reagents, such as KMnO4, (2) evaluate the dopant "paramagnetic" ions that are present as clusters or in the OMS framework, and (3) determine AOS of other mixed-valent/single oxidation state ion systems, such as Mo3+(3d3)-Mo4+(3d2) systems and Fe3+ in FeCl3.

  8. Solid state chemistry of rare earth oxides. Final report, September 1, 1950--July 31, 1977

    International Nuclear Information System (INIS)

    Eyring, L.

    1977-07-01

    Work under Contract E(11-1)-1109 and its antecedents has been primarily for the purpose of obtaining detailed thermodynamic, kinetic and structural information on the complex rare earth oxides of praseodymium and terbium. These systems exhibit homologous series of ordered phases, order-disorder transformations, wide-range nonstoichiometric phases, chemical hysteresis in two-phase regions and many other solid state reaction phenomena. Fluorite-related materials of importance to ERDA occur as nuclear fuels, radiation power sources, insulators and solid electrolytes. The rare earth oxides serve directly as model systems for such similar materials and, in a more general sense, they serve as models of solids in general since they exhibit nearly the full range of solid state properties

  9. Solid State Electrochemical Sensors for Nitrogen Oxide (NOx) Detection in Lean Exhaust Gases

    OpenAIRE

    Rheaume, Jonathan Michael

    2010-01-01

    Solid state electrochemical sensors that measure nitrogen oxides (NOx) in lean exhaust have been investigated in order to help meet future on-board diagnostic (OBD) regulations for diesel vehicles. This impedancemetric detection technology consists of a planar, single cell sensor design with various sensing electrode materials and yttria-stabilized zirconia (YSZ) as the electrolyte. No reference to ambient air is required. An impedance analysis method yields a signal that is proportional to t...

  10. Quantitative evaluation of the effect of H2O degassing on the oxidation state of magmas

    Science.gov (United States)

    Lange, R. A.; Waters, L.

    2014-12-01

    The extent to which degassing of the H2O component affects the oxidation state of hydrous magmas is widely debated. Several researchers have examined how degassing of mixed H-C-O-S-Cl fluids may change the Fe3+/FeT ratio of various magmas, whereas our focus is on the H2O component. There are two ways that degassing of H2O by itself may cause oxidation: (1) the reaction: H2O (melt) + 2FeO (melt) = H2 (fluid) + Fe2O3 (melt), and/or (2) if dissolved water preferentially enhances the activity of ferrous vs. ferric iron in magmatic liquids. In this study, a comparison is made between the pre-eruptive oxidation states of 14 crystal-poor, jet-black obsidian samples (obtained from two Fe-Ti oxides) and their post-eruptive values (analyzed with the Wilson 1960 titration method tested against USGS standards). The obsidians are from Medicine Lake (CA), Long Valley (CA), and the western Mexican arc; all have low FeOT (1.1-2.1 wt%), rendering their Fe2+/Fe3+ ratios highly sensitive to the possible effects of substantial H2O degassing. The Fe-Ti oxide thermometer/oxybarometer of Ghiorso and Evans, (2008) gave temperatures for the 14 samples that range for 720 to 940°C and ΔNNO values of -0.9 to +1.4. With temperature known, the plagioclase-liquid hygrometer was applied and show that ≤ 6.5 wt% H2O was dissolved in the melts prior to eruption. In addition, pre-eruptive Cl and S concentrations were constrained on the basis of apatite analyses (Webster et al., 2009) and sulfur concentrations needed for saturation with pyrrhotite (Clemente et al., 2004), respectively. Maximum pre-eruptive chlorine and sulfur contents are 6000 and 200 ppm, respectively. After eruption, the rhyolites lost nearly all of their volatiles. Our results indicate no detectable change between pre- and post-eruptive Fe2+ concentrations, with an average deviation of ± 0.1 wt % FeO. Although degassing of large concentrations of S and/or Cl may affect the oxidation state of magmas, at the pre-eruptive levels

  11. Arsenic (+3 oxidation state) methyltransferase and the inorganic arsenic methylation phenotype

    International Nuclear Information System (INIS)

    Li Jiaxin; Waters, Stephen B.; Drobna, Zuzana; Devesa, Vicenta; Styblo, Miroslav; Thomas, David J.

    2005-01-01

    Inorganic arsenic is enzymatically methylated; hence, its ingestion results in exposure to the parent compound and various methylated arsenicals. Both experimental and epidemiological evidences suggest that some of the adverse health effects associated with chronic exposure to inorganic arsenic may be mediated by these methylated metabolites. If i As methylation is an activation process, then the phenotype for inorganic arsenic methylation may determine risk associated with exposure to this metalloid. We examined inorganic arsenic methylation phenotypes and arsenic (+3 oxidation state) methyltransferase genotypes in four species: three that methylate inorganic arsenic (human (Homo sapiens), rat (Rattus norwegicus), and mouse (Mus musculus)) and one that does not methylate inorganic arsenic (chimpanzee, Pan troglodytes). The predicted protein products from arsenic (+3 oxidation state) methyltransferase are similar in size for rat (369 amino acid residues), mouse (376 residues), and human (375 residues). By comparison, a 275-nucleotide deletion beginning at nucleotide 612 in the chimpanzee gene sequence causes a frameshift that leads to a nonsense mutation for a premature stop codon after amino acid 205. The null phenotype for inorganic arsenic methylation in the chimpanzee is likely due to the deletion in the gene for arsenic (+3 oxidation state) methyltransferase that yields an inactive truncated protein. This lineage-specific loss of function caused by the deletion event must have occurred in the Pan lineage after Homo-Pan divergence about 5 million years ago

  12. Oxidized Nitrogen Balance over 15 Months at Rural and Urban New York State Locations

    Science.gov (United States)

    Schwab, J. J.; Ninneman, M.; Marto, J.; Edgerton, E. S.; Blanchard, C. L.; Shaw, S. L.

    2017-12-01

    Continuous measurements of oxidized nitrogen species (NO, NO2, and HNO3), families of species (NOy, alkyl nitrates [or ANs], and peroxyacetyl nitrates [or PANs]), and particle nitrate (pNO3) were carried out for a fifteen-month period from August 2016 through October 2017 at two locations in New York State. The two sites were a rural research station at Pinnacle State Park in Addison, NY and an urban research station at Queens College in New York City. Four different chemiluminescence analyzers with various converters and denuders were employed to make these measurements. Instrumentation used for the study will be described, as well as some of the challenges created by combining data from these independent analyzers to address the oxidized nitrogen budget at the two sites. The Pinnacle State Park site often experiences quite clean air with low ppb levels of total NOy and a greater fraction of oxidized nitrogen products (NOz species). This contrasts with the urban Queens College location, which experiences stronger NOx sources. Seasonal differences in the NOx/NOy and NOz/NOy ratios, and the makeup of the NOz species, are also significant and will be explored in the presentation.

  13. Single Crystal Growth of Pure Co3+ Oxidation State Material LaSrCoO4

    Directory of Open Access Journals (Sweden)

    Hanjie Guo

    2016-08-01

    Full Text Available We report on the single crystal growth of the single-layer perovskite cobaltate LaSrCoO4 that was grown by the optical floating zone method using high oxygen pressures. Phase purity and single crystallinity were confirmed by X-ray diffraction techniques. The pure Co3+ oxidation state was confirmed by X-ray absorbtion spectroscopy measurements. A transition to a spin glass state is observed at ∼7 K in magnetic susceptibility and specific heat measurements.

  14. Raman spectroscopic study of the oxidation state of Eu in molten LiCl-KCl

    Energy Technology Data Exchange (ETDEWEB)

    Park, Seung; Yun, Jong-Il [KAIST, Daejeon(Korea, Republic of)

    2016-10-15

    Spectroscopy can provide high reliability for the quantitative analysis of such system. The molar absorptivity of Eu(II) at 325 nm is reported as about 1645 M{sup -1}cm{sup -1}, which is too high to apply to higher concentration. A high-temperature Raman spectroscopy has been set and employed for analyzing the molecular structure and coordination complex and investigating the oxidation state of europium in molten LiCl-KCl. Europium can be present in divalent state while many other lanthanides exist in trivalent state. The thermodynamic properties of europium ions have been studied using electrochemical methods, spectroscopic methods, and EPR technique. Although there has been discrepancy of the reduced amount of europium in previous works, the majority of Eu(III) is thought to be reduced to Eu(II) in molten LiCl-KCl spontaneously at relatively low concentration (< 7.5 × 10{sup -4} M). Raman spectroscopy was employed to investigate the oxidation state of EuClx in LiCl-KCl at 500 .deg. C. The Raman scattering results suggest the majority of trivalent europium is reduced to divalent state with the composition change by vaporization. The Raman bands show highly asymmetric structure, quite different from regular octahedral structure.

  15. Molecular water oxidation mechanisms followed by transition metals: state of the art.

    Science.gov (United States)

    Sala, Xavier; Maji, Somnath; Bofill, Roger; García-Antón, Jordi; Escriche, Lluís; Llobet, Antoni

    2014-02-18

    One clean alternative to fossil fuels would be to split water using sunlight. However, to achieve this goal, researchers still need to fully understand and control several key chemical reactions. One of them is the catalytic oxidation of water to molecular oxygen, which also occurs at the oxygen evolving center of photosystem II in green plants and algae. Despite its importance for biology and renewable energy, the mechanism of this reaction is not fully understood. Transition metal water oxidation catalysts in homogeneous media offer a superb platform for researchers to investigate and extract the crucial information to describe the different steps involved in this complex reaction accurately. The mechanistic information extracted at a molecular level allows researchers to understand both the factors that govern this reaction and the ones that derail the system to cause decomposition. As a result, rugged and efficient water oxidation catalysts with potential technological applications can be developed. In this Account, we discuss the current mechanistic understanding of the water oxidation reaction catalyzed by transition metals in the homogeneous phase, based on work developed in our laboratories and complemented by research from other groups. Rather than reviewing all of the catalysts described to date, we focus systematically on the several key elements and their rationale from molecules studied in homogeneous media. We organize these catalysts based on how the crucial oxygen-oxygen bond step takes place, whether via a water nucleophilic attack or via the interaction of two M-O units, rather than based on the nuclearity of the water oxidation catalysts. Furthermore we have used DFT methodology to characterize key intermediates and transition states. The combination of both theory and experiments has allowed us to get a complete view of the water oxidation cycle for the different catalysts studied. Finally, we also describe the various deactivation pathways for

  16. Application of powerful oxidizers in the synthesis of new high-oxidation state actinide and related species

    International Nuclear Information System (INIS)

    Yeh, S.M.

    1984-11-01

    The fluorinating and oxide scavenging ability of XeF 6 have been studied by bringing XeF 6 into interaction with oxide-fluoride compounds of the third-transition-series elements (W, Re and Os) and uranium, in their highest oxidation states. A + MOF 5 - and A + M 2 O 2 F 9 - (A = K or Cs, M = W or U) were converted to A + MF 7 - by XeF 6 , but the rhenium and osmium compounds, K + ReO 2 F 4 - and XeF 5 + OsO 3 F 3 - , resisted interaction with XeF 6 . Strong interactions between XeF 2 or KrF 2 and the solvent have been observed for their solutions in anhydrous HF. Both XeF 2 and KrF 2 are seen to be effective in breaking up the polymeric (HF)/sub n/ chains. Only weak interactions occur between cations and anions of KrF + AuF 6 - and Kr 2 F 3 + AuF 6 - in HF. The AuF 6 - anions are slightly distorted from O/sub h/ symmetry. Kr 2 F 3 + cations in HF have the same dissymmetric V-shape which occurs in crystalline salts. A low-temperature orthorhombic form, β-ReF 6 + SbF 6 - , a high-temperature rhombohedral form, α-ReF 6 + SbF 6 - , and a ReF 6 + AuF 6 - have been prepared. These compounds possess only kinetic stability at ambient temperature and at approx. 20 0 C are best represented as ReF 6 + ReF 7 MF 6 - MF 5 . Thermochemical energy evaluations indicate that the ionization potential of ReF 6 is 261 kcal mole -1 and that the fluoride-ion affinity of ReF 6 + is -214 kcal mole -1 . This is more exothermal than the corresponding process for IF 6 + (-208 kcal mole -1 ). In contrast, ReOF 5 is shown to be a better fluoro-base than IOF 5 and also is a better base than ReF 7 . ReOF 4 + MF 6 - (M = Sb, Au and As) salts are of higher thermal stability than their ReF 6 + MF 6 - analogues

  17. Synchrotron Micro-XANES Measurements of Vanadium Oxidation State in Glasses as a Function of Oxygen Fugacity: Experimental Calibration of Data Relevant to Partition Coefficient Determination

    Science.gov (United States)

    Delaney, J. S.; Sutton, S. R.; Newville, M.; Jones, J. H.; Hanson, B.; Dyar, M. D.; Schreiber, H.

    2000-01-01

    Oxidation state microanalyses for V in glass have been made by calibrating XANES spectral features with optical spectroscopic measurements. The oxidation state change with fugacity of O2 will strongly influence partitioning results.

  18. Chemical state analysis of oxidation products on steel surface by conversion electron Moessbauer spectrometry

    International Nuclear Information System (INIS)

    Ujihira, Yusuke; Nomura, Kiyoshi

    1978-01-01

    The polished NT-70H steel (Fe: 95.97%, C: 0.56%, diameter: 5 cm, thickness: 0.5 cm) was immersed in deionized water or in solutions containing (0.25 -- 0.5) M of chloride, sulfate and nitrate ions. The chemical states of oxidation products of iron on the surface were identified through the analysis of conversion electron Moessbauer spectra (CEMS). CEMS of the steel surface, which had been dipped in deionized water, revealed that γ-FeOOH was formed on the surface. The thickness of γ-FeOOH layer increased with the increase of the duration of dipping. Dissolved oxygen in the solution played an essential role in the oxidation of iron to γ-FeOOH. Oxidation product of iron dipped in the 0.5 M sodium chloride solution was identified as γ-FeOOH. Amorphous paramagnetic iron (III) compound tended to form in the presence of hydrogen peroxide or ammonium ions in the solutions. The increase of alkalinity of the solution up to pH 12 suppressed the oxidation rate and assisted the formation of green rust, which was confirmed by the appearance of the quadrupole splitting peaks of the green rust. In the 0.25 M sodium sulfate solution, oxidation of the steel surface proceeded slowly and the quadrupole splitting peaks of Fe(OH) 2 were seen in the CEMS. The peak intensity of Fe(OH) 2 gradually decreased and that of γ-FeOOH increased by the extension of immersion of steel in the solution. Magnetite (Fe 3 O 4 ) layer was developed beneath the γ-FeOOH layer, when steel was dipped in 0.5 M sodium nitrate solution. However, the peaks of Fe 3 O 4 were not seen on CEMS of steel surface immersed in 0.5 M ammonium nitrate solution. Thus, applying the feasibility of CEMS for the characterization of oxidated compounds of iron on the steel surface formed by the immersion in solutions, the oxidation mechanism of the steel surface was discussed based upon the results of chemical state analyses. (author)

  19. Room air versus carbon dioxide pneumoperitoneum: effects on oxidative state, apoptosis and histology of splanchnic organs.

    Science.gov (United States)

    Ypsilantis, Petros; Lambropoulou, Maria; Tentes, Ioannis; Chryssidou, Maria; Georgantas, Themistoklis; Simopoulos, Constantinos

    2016-04-01

    Although CO2 is the insufflation gas of choice in laparoscopic procedures, room air is usually used in natural orifice transluminal endoscopic surgery. The aim of the present study was to compare the safety of room air versus CO2 pneumoperitoneum in terms of their effect on the oxidative state, apoptosis and tissue injury of splanchnic organs. Eighteen Wistar rats were assigned to three groups (n = 6 per group) and were subjected to 8 mm Hg room air (group Pne-Air) or CO2 pneumoperitoneum (group Pne-CO2) or sham operation for 60 min. Forty-five minutes postdeflation, tissue samples were excised from the liver, stomach, ileum and kidneys for reduced glutathione-to-glutathione disulfide (GSH/GSSG) ratio, caspase-8 and caspase-3 and hypoxia-inducible factor-1α (HIF-1α) immunohistochemical assessment and histopathologic examination. GSH/GSSG ratio substantially declined in both pneumoperitoneum groups. No change was noted in HIF-1α expression. Mild upregulation of caspase-8 and caspase-3 was noted in both pneumoperitoneum groups being less pronounced in group Pne-Air. Histopathologic score was increased in all organs studied, but the stomach, in both pneumoperitoneum groups. Pneumoperitoneum established by either room air or CO2 induced substantial oxidative stress, mild apoptosis and mild tissue injury in splanchnic organs. While air pneumoperitoneum conferred a less pronounced apoptotic effect, the oxidative state and histopathologic profile of splanchnic organs did not differ between insufflation gases.

  20. The influence of iridium chemical oxidation state on the performance and durability of oxygen evolution catalysts in PEM electrolysis

    Science.gov (United States)

    Siracusano, S.; Baglio, V.; Grigoriev, S. A.; Merlo, L.; Fateev, V. N.; Aricò, A. S.

    2017-10-01

    Nanosized Ir-black (3 nm) and Ir-oxide (5 nm) oxygen evolution electrocatalysts showing high performance in polymer electrolyte membrane (PEM) water electrolysis based on Aquivion® short-side chain ionomer membrane are investigated to understand the role of the Ir oxidation state on the electrocatalytic activity and stability. Despite the smaller mean crystallite size, the Ir-black electrocatalyst shows significantly lower initial performance than the Ir-oxide. During operation at high current density, the Ir-black shows a decrease of cell potential with time whereas the Ir-oxide catalyst shows increasing cell potential resulting in a degradation rate of about 10 μV/h, approaching 1000 h. The unusual behaviour of the Ir-black results from the oxidation of metallic Ir to IrOx. The Ir-oxide catalyst shows instead a hydrated structure on the surface and a negative shift of about 0.5 eV for the Ir 4f binding energy after 1000 h electrolysis operation. This corresponds to the formation of a sub-stoichiometric Ir-oxide on the surface. These results indicate that a hydrated IrO2 with high oxidation state on the surface is favourable in decreasing the oxygen evolution overpotential. Modifications of the Ir chemical oxidation state during operation can affect significantly the catalytic activity and durability of the electrolysis system.

  1. Diversity of Chemical Bonding and Oxidation States in MS4 Molecules of Group 8 Elements.

    Science.gov (United States)

    Huang, Wei; Jiang, Ning; Schwarz, W H Eugen; Yang, Ping; Li, Jun

    2017-08-04

    The geometric and electronic ground-state structures of 30 isomers of six MS 4 molecules (M=Group 8 metals Fe, Ru, Os, Hs, Sm, and Pu) have been studied by using quantum-chemical density functional theory and correlated wavefunction approaches. The MS 4 species were compared to analogous MO 4 species recently investigated (W. Huang, W.-H. Xu, W. H. E. Schwarz, J. Li, Inorg. Chem. 2016, 55, 4616). A metal oxidation state (MOS) with a high value of eight appeared in the low-spin singlet T d geometric species (Os,Hs)S 4 and (Ru,Os,Hs)O 4 , whereas a low MOS of two appeared in the high-spin septet D 2d species Fe(S 2 ) 2 and (slightly excited) metastable Fe(O 2 ) 2 . The ground states of all other molecules had intermediate MOS values, with S 2- , S 2 2- , S 2 1- (and O 2- , O 1- , O 2 2- , O 2 1- ) ligands bonded by ionic, covalent, and correlative contributions. The known tendencies toward lower MOS on going from oxides to sulfides, from Hs to Os to Ru, and from Pu to Sm, and the specific behavior of Fe, were found to arise from the different atomic orbital energies and radii of the (n-1)p core and (n-1)d and (n-2)f valence shells of the metal atoms in row n of the periodic table. The comparative results of the electronic and geometric structures of the MO 4 and MS 4 species provides insight into the periodicity of oxidation states and bonding. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Visible light photoreactivity from hybridization states between carbon nitride bandgap states and valence states in Nb and Ti oxides

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hosik, E-mail: hosiklee@gmail.com [School of Mechanical and Advanced Materials Engineering, Ulsan National Institute of Science and Technology (UNIST), Unist-gil 100 Eonyang-eup, Ulsan 689-798 (Korea, Republic of); Ohno, Takahisa, E-mail: OHNO.Takahisa@nims.go.jp [Global Research Center for Environment and Energy based on Nanomaterials Science (GREEN), National Institute for Material Science, 1-2-1 Sengen, Tsukuba (Japan); Computational Materials Science Unit (CMSU), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0047 (Japan)

    2013-03-29

    Highlights: ► Origin of bandgap reduction for visible photoreactivity is suggested. ► Carbon nitride adsorption in interlayer space can induce the bandgap reduction. ► The electronic structures are studied by density functional theory calculations. - Abstract: For better efficiency as photocatalysts, N-doping for visible light reactivity has been intensively studied in Lamellar niobic and titanic solid acids (HNb{sub 3}O{sub 8}, H{sub 2}Ti{sub 4}O{sub 9}), and its microscopic structures have been debated in this decade. We calculate the layered solid acids’ structures and bandgaps. Bandgap reduction by carbon nitride adsorption in interlayer space is observed computationally. It originates from localized nitrogen states which form delocalized top-valence states by hybridizing with the host oxygen states and can contribute to photo-current.

  3. Introducing a Simple Equation to Express Oxidation States as an Alternative to Using Rules Associated with Words Alone

    Science.gov (United States)

    Minkiewicz, Piotr; Darewicz, Malgorzata; Iwaniak, Anna

    2018-01-01

    A simple equation to calculate the oxidation states (oxidation numbers) of individual atoms in molecules and ions may be introduced instead of rules associated with words alone. The equation includes two of three categories of bonds, classified as proposed by Goodstein: number of bonds with more electronegative atoms and number of bonds with less…

  4. Homogeneity of Continuum Model of an Unsteady State Fixed Bed Reactor for Lean CH4 Oxidation

    Directory of Open Access Journals (Sweden)

    Subagjo

    2014-07-01

    Full Text Available In this study, the homogeneity of the continuum model of a fixed bed reactor operated in steady state and unsteady state systems for lean CH4 oxidation is investigated. The steady-state fixed bed reactor system was operated under once-through direction, while the unsteady-state fixed bed reactor system was operated under flow reversal. The governing equations consisting of mass and energy balances were solved using the FlexPDE software package, version 6. The model selection is indispensable for an effective calculation since the simulation of a reverse flow reactor is time-consuming. The homogeneous and heterogeneous models for steady state operation gave similar conversions and temperature profiles, with a deviation of 0.12 to 0.14%. For reverse flow operation, the deviations of the continuum models of thepseudo-homogeneous and heterogeneous models were in the range of 25-65%. It is suggested that pseudo-homogeneous models can be applied to steady state systems, whereas heterogeneous models have to be applied to unsteady state systems.

  5. SOLID STATE ENERGY CONVERSION ALLIANCE (SECA) SOLID OXIDE FUEL CELL PROGRAM

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen Minh; Jim Powers

    2003-10-01

    This report summarizes the work performed for April 2003--September 2003 reporting period under Cooperative Agreement DE-FC26-01NT41245 for the U.S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled ''Solid State Energy Conversion Alliance (SECA) Solid oxide Fuel Cell Program''. During this reporting period, the conceptual system design activity was completed. The system design, including strategies for startup, normal operation and shutdown, was defined. Sealant and stack materials for the solid oxide fuel cell (SOFC) stack were identified which are capable of meeting the thermal cycling and degradation requirements. A cell module was tested which achieved a stable performance of 0.238 W/cm{sup 2} at 95% fuel utilization. The external fuel processor design was completed and fabrication begun. Several other advances were made on various aspects of the SOFC system, which are detailed in this report.

  6. SOLID STATE ENERGY CONVERSION ALLIANCE (SECA) SOLID OXIDE FUEL CELL PROGRAM

    Energy Technology Data Exchange (ETDEWEB)

    Unknown

    2003-06-01

    This report summarizes the progress made during the September 2001-March 2002 reporting period under Cooperative Agreement DE-FC26-01NT41245 for the U. S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled ''Solid State Energy Conversion Alliance (SECA) Solid Oxide Fuel Cell Program''. The program focuses on the development of a low-cost, high-performance 3-to-10-kW solid oxide fuel cell (SOFC) system suitable for a broad spectrum of power-generation applications. The overall objective of the program is to demonstrate a modular SOFC system that can be configured to create highly efficient, cost-competitive, and environmentally benign power plants tailored to specific markets. When fully developed, the system will meet the efficiency, performance, life, and cost goals for future commercial power plants.

  7. Surface State Capture Cross-Section at the Interface between Silicon and Hafnium Oxide

    Directory of Open Access Journals (Sweden)

    Fu-Chien Chiu

    2013-01-01

    Full Text Available The interfacial properties between silicon and hafnium oxide (HfO2 are explored by the gated-diode method and the subthreshold measurement. The density of interface-trapped charges, the current induced by surface defect centers, the surface recombination velocity, and the surface state capture cross-section are obtained in this work. Among the interfacial properties, the surface state capture cross-section is approximately constant even if the postdeposition annealing condition is changed. This effective capture cross-section of surface states is about 2.4 × 10−15 cm2, which may be an inherent nature in the HfO2/Si interface.

  8. Control of lipid oxidation during exercise: role of energy state and mitochondrial factors

    DEFF Research Database (Denmark)

    Sahlin, K; Harris, R C

    2008-01-01

    Despite considerable progress during recent years our understanding of how lipid oxidation (LOx) is controlled during exercise remains incomplete. This review focuses on the role of mitochondria and energy state in the control of LOx. LOx increases in parallel with increased energy demand up...... to an exercise intensity of about 50-60% of VO(2max) after which the contribution of lipid decreases. The switch from lipid to carbohydrate (CHO) is of energetic advantage due to the increased ATP/O(2) yield. In the low-intensity domain (energy state will stimulate both LOx...... during high-intensity exercise. Another potential mechanism, suggested in this review, is that Acyl-CoA synthetase (ACS), an initial step in LCFA catabolism, functions as a regulator of LOx. ACS activity is suggested to be under control of CoASH and energy state. Furthermore, evidence exists...

  9. Optically induced bistable states in metal/tunnel-oxide/semiconductor /MTOS/ junctions

    Science.gov (United States)

    Lai, S. K.; Dressendorfer, P. V.; Ma, T. P.; Barker, R. C.

    1981-01-01

    A new switching phenomenon in metal-oxide semiconductor tunnel junction has been discovered. With a sufficiently large negative bias applied to the electrode, incident visible light of intensity greater than about 1 microW/sq cm causes the reverse-biased junction to switch from a low-current to a high-current state. It is believed that hot-electron-induced impact ionization provides the positive feedback necessary for switching, and causes the junction to remain in its high-current state after the optical excitation is removed. The junction may be switched back to the low-current state electrically. The basic junction characteristics have been measured, and a simple model for the switching phenomenon has been developed.

  10. Evolution of the Oxidation State of the Earth's Mantle: Challenges of High Pressure Quenching

    Science.gov (United States)

    Danielson, L. R.; Righter, K.; Keller, L.; Christoffersen, R.; Rahman, Z.

    2015-01-01

    The oxidation state of the Earth's mantle during formation remains an unresolved question, whether it was constant throughout planetary accretion, transitioned from reduced to oxidized, or from oxidized to reduced. We investigate the stability of Fe3+ at depth, in order to constrain processes (water, late accretion, dissociation of FeO) which may reduce or oxidize the Earth's mantle. Experiments of more mafic compositions and at higher pressures commonly form a polyphase quench intergrowth composed primarily of pyroxenes, with interstitial glass which hosts nearly all of the more volatile minor elements. In our previous experiments on shergottite compositions, variable fO2, T, and P is less than 4 GPa, Fe3+/TotFe decreased slightly with increasing P, similar to terrestrial basalt. For oxidizing experiments less than 7GPa, Fe3+/TotFe decreased as well, but it's unclear from previous modelling whether the deeper mantle could retain significant Fe3+. Our current experiments expand our pressure range deeper into the Earth's mantle and focus on compositions and conditions relevant to the early Earth. Experiments with Knippa basalt as the starting composition were conducted at 1-8 GPa and 1800 C, using a molybdenum capsule to set the fO2 near IW, by buffering with Mo-MoO3. TEM and EELS analyses revealed the run products from 7-8 GPa quenched to polycrystalline phases, with the major phase pyroxene containing approximately equal Fe3+/2+. A number of different approaches have been employed to produce glassy samples that can be measured by EELS and XANES. A more intermediate andesite was used in one experiment, and decompression during quenching was attempted after, but both resulted in a finer grained polyphase texture. Experiments are currently underway to test different capsule materials may affect quench texture. A preliminary experiment using liquid nitrogen to greatly enhance the rate of cooling of the assembly has also been attempted and this technique will be

  11. Determination of Model Kinetics for Forced Unsteady State Operation of Catalytic CH4 Oxidation

    Directory of Open Access Journals (Sweden)

    Effendy Mohammad

    2016-01-01

    Full Text Available The catalytic oxidation of methane for abating the emission vented from coal mine or natural gas transportation has been known as most reliable method. A reverse flow reactor operation has been widely used to oxidize this methane emission due to its capability for autothermal operation and heat production. The design of the reverse flow reactor requires a proper kinetic rate expression, which should be developed based on the operating condition. The kinetic rate obtained in the steady state condition cannot be applied for designing the reactor operated under unsteady state condition. Therefore, new approach to develop the dynamic kinetic rate expression becomes indispensable, particularly for periodic operation such as reverse flow reactor. This paper presents a novel method to develop the kinetic rate expression applied for unsteady state operation. The model reaction of the catalytic methane oxidation over Pt/-Al2O3 catalyst was used with kinetic parameter determined from laboratory experiments. The reactor used was a fixed bed, once-through operation, with a composition modulation in the feed gas. The switching time was set at 3 min by varying the feed concentration, feed flow rate, and reaction temperature. The concentrations of methane in the feed and product were measured and analysed using gas chromatography. The steady state condition for obtaining the kinetic rate expression was taken as a base case and as a way to judge its appropriateness to be applied for dynamic system. A Langmuir-Hinshelwood reaction rate model was developed. The time period during one cycle was divided into some segments, depending on the ratio of CH4/O2. The experimental result shows that there were kinetic regimes occur during one cycle: kinetic regime controlled by intrinsic surface reaction and kinetic regime controlled by external diffusion. The kinetic rate obtained in the steady state operation was not appropriate when applied for unsteady state operation

  12. Quantitative chemical state XPS analysis of first row transition metals, oxides and hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Biesinger, M C; Payne, B P; McIntryre, N S [Department of Chemistry, University of Western Ontario, London, Ontario, N6A 5B7 (Canada); Hart, B R; Lau, L Wm [Surface Science Western, Room G1, Western Science Centre, University of Western Ontario, London, Ontario, N6A 5B7 (Canada); Grosvenor, A P [Department of Chemistry, Gunning/Lemieux Chemistry Centre, University of Alberta, Edmonton, Alberta, T6G 2G2 (Canada); Smart, R StC [ACeSSS, Applied Centre for Structural and Synchrotron Studies, University of South Australia, Mawson Lakes, SA 5095 (Australia)], E-mail: biesingr@uwo.ca

    2008-03-15

    Practical quantitative chemical state X-ray photoelectron spectroscopy (XPS) analysis of first row transition metals, oxides and hydroxides is challenging due to the complexity of their M 2p spectra. Complex multiplet splitting, shake-up and plasmon loss structure can play a role in the interpretation of the chemical states present. This paper will show practical curve fitting procedures for the quantitative measurement of different chemical states for metal oxides and hydroxides from a survey of transition metals. It will also discuss some of the limitations and pitfalls present as well as give practical examples of their successful use. These curve-fitting procedures are based on 1) standard spectra from quality reference samples, 2) a survey of appropriate literature databases and/or a compilation of literature references, 3) fitting of multiplet split spectra based on spectra of numerous reference materials and theoretical modelling, 4) spectral subtractions routines, again using reference spectra, and 5) specific literature references where fitting procedures are available.

  13. Quantitative chemical state XPS analysis of first row transition metals, oxides and hydroxides

    International Nuclear Information System (INIS)

    Biesinger, M C; Payne, B P; McIntryre, N S; Hart, B R; Lau, L Wm; Grosvenor, A P; Smart, R StC

    2008-01-01

    Practical quantitative chemical state X-ray photoelectron spectroscopy (XPS) analysis of first row transition metals, oxides and hydroxides is challenging due to the complexity of their M 2p spectra. Complex multiplet splitting, shake-up and plasmon loss structure can play a role in the interpretation of the chemical states present. This paper will show practical curve fitting procedures for the quantitative measurement of different chemical states for metal oxides and hydroxides from a survey of transition metals. It will also discuss some of the limitations and pitfalls present as well as give practical examples of their successful use. These curve-fitting procedures are based on 1) standard spectra from quality reference samples, 2) a survey of appropriate literature databases and/or a compilation of literature references, 3) fitting of multiplet split spectra based on spectra of numerous reference materials and theoretical modelling, 4) spectral subtractions routines, again using reference spectra, and 5) specific literature references where fitting procedures are available

  14. Solid-state electrochromic cell with anodic iridium oxide film electrodes

    International Nuclear Information System (INIS)

    Dautremont-Smith, W.C.; Beni, G.; Schiavone, L.M.; Shay, J.L.

    1979-01-01

    A new solid-state electrochromic cell has been fabricated using an anodic iridium oxide film (AIROF) display electrode. The cell has the symmetric sandwich structure AIROFvertical-barNafionvertical-barAIROF, with the Nafion solid electrolyte opacified by an in situ precipitation technique. A symmetric square-wave voltage of 1.5 V amplitude produces clearly perceivable color changes from pale to dark blue-gray in approx. =1 sec when viewed in diffuse reflection. Good open-circuit optical memory is exhibited:

  15. N-Oxide-N-oxide interactions and Cl...Cl halogen bonds in pentachloropyridine N-oxide: the many-body approach to interactions in the crystal state.

    Science.gov (United States)

    Wzgarda-Raj, Kinga; Rybarczyk-Pirek, Agnieszka J; Wojtulewski, Sławomir; Palusiak, Marcin

    2018-02-01

    Pentachloropyridine N-oxide, C 5 Cl 5 NO, crystallizes in the monoclinic space group P2 1 /c. In the crystal structure, molecules are linked by C-Cl...Cl halogen bonds into infinite ribbons extending along the crystallographic [100] direction. These molecular aggregates are further stabilized by very short intermolecular N-oxide-N-oxide interactions into herringbone motifs. Computations based on quantum chemistry methods allowed for a more detailed description of the N-oxide-N-oxide interactions and Cl...Cl halogen bonds. For this purpose, Hirshfeld surface analysis and the many-body approach to interaction energy were applied.

  16. Evaluating chemical extraction techniques for the determination of uranium oxidation state in reduced aquifer sediments

    Science.gov (United States)

    Stoliker, Deborah L.; Campbell, Kate M.; Fox, Patricia M.; Singer, David M.; Kaviani, Nazila; Carey, Minna; Peck, Nicole E.; Barger, John R.; Kent, Douglas B.; Davis, James A.

    2013-01-01

    Extraction techniques utilizing high pH and (bi)carbonate concentrations were evaluated for their efficacy in determining the oxidation state of uranium (U) in reduced sediments collected from Rifle, CO. Differences in dissolved concentrations between oxic and anoxic extractions have been proposed as a means to quantify the U(VI) and U(IV) content of sediments. An additional step was added to anoxic extractions using a strong anion exchange resin to separate dissolved U(IV) and U(VI). X-ray spectroscopy showed that U(IV) in the sediments was present as polymerized precipitates similar to uraninite and/or less ordered U(IV), referred to as non-uraninite U(IV) species associated with biomass (NUSAB). Extractions of sediment containing both uraninite and NUSAB displayed higher dissolved uranium concentrations under oxic than anoxic conditions while extractions of sediment dominated by NUSAB resulted in identical dissolved U concentrations. Dissolved U(IV) was rapidly oxidized under anoxic conditions in all experiments. Uraninite reacted minimally under anoxic conditions but thermodynamic calculations show that its propensity to oxidize is sensitive to solution chemistry and sediment mineralogy. A universal method for quantification of U(IV) and U(VI) in sediments has not yet been developed but the chemical extractions, when combined with solid-phase characterization, have a narrow range of applicability for sediments without U(VI).

  17. Nanoscale probing of bandgap states on oxide particles using electron energy-loss spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Qianlang [School for the Engineering of Matter, Transport and Energy, Arizona State University, 85287 AZ (United States); March, Katia [Laboratoire de Physique des Solides, Bâtiment 510, Université Paris-Sud, 91405 Orsay Cedex (France); Crozier, Peter A., E-mail: CROZIER@asu.edu [School for the Engineering of Matter, Transport and Energy, Arizona State University, 85287 AZ (United States)

    2017-07-15

    Surface and near-surface electronic states were probed with nanometer spatial resolution in MgO and TiO{sub 2} anatase nanoparticles using ultra-high energy resolution electron energy-loss spectroscopy (EELS) coupled to a scanning transmission electron microscope (STEM). This combination allows the surface electronic structure determined with spectroscopy to be correlated with nanoparticle size, morphology, facet etc. By acquiring the spectra in aloof beam mode, radiation damage to the surface can be significantly reduced while maintaining the nanometer spatial resolution. MgO and TiO{sub 2} showed very different bandgap features associated with the surface/sub-surface layer of the nanoparticles. Spectral simulations based on dielectric theory and density of states models showed that a plateau feature found in the pre-bandgap region in the spectra from (100) surfaces of 60 nm MgO nanocubes is consistent with a thin hydroxide surface layer. The spectroscopy shows that this hydroxide species gives rise to a broad filled surface state at 1.1 eV above the MgO valence band. At the surfaces of TiO{sub 2} nanoparticles, pronounced peaks were observed in the bandgap region, which could not be well fitted to defect states. In this case, the high refractive index and large particle size may make Cherenkov or guided light modes the likely causes of the peaks. - Highlights: • Bandgap states detected with aloof beam monochromated EELS on oxide nanoparticle surfaces. • Dielectric theory applied to simulate the spectra and interpret surface structure. • Density of states models also be employed to understand the surface electronic structure. • In MgO, one states associate with water species was found close to the valence band edge. • In anatase, two mid-gap states associated with point defects were found.

  18. Adsorption of CO, CO2, H2, and H2O on titania surfaces with different oxidation states

    International Nuclear Information System (INIS)

    Raupp, G.B.; Dumesic, J.A.

    1985-01-01

    The adsorptive properties of titania surfaces with different oxidation states were proved by temperature-programmed desorption (TPD) of CO, H 2 , CO 2 , and H 2 O. Auger electron spectroscopy and X-ray photoelectron spectroscopy revealed that vacuum annealing an oxidized titanium foil at temperatures from 300 to 800 K was an effective means of systematically varying the average surface oxidation state from Ti 4+ to Ti 2+ . Carbon monoxide weakly adsorbed (desorption energy of 44-49 kJ x mol -1 ) in a carbonyl fashion on coordinatively unsaturated cation sites. Titania surfaces were inert with respect to H 2 adsorption and dissociation. Carbon dioxide adsorbed in a linear molecular fashion. Water adsorbed both molecularly and dissociatively. Results are discussed in terms of the role of titania oxidation state in CO hydrogenation over titania-supported metal catalysts. 74 references, 7 figures

  19. The effect of interfaces on solid-state reactions between oxides

    International Nuclear Information System (INIS)

    Johnson, M.T.; Carter, C.B.

    1998-01-01

    A thin-film geometry has been used to study fundamental solid-state reaction processes occurring at interfaces in two spinel-forming oxide systems. In the first system, NiO/Al 2 O 3 , epitactic NiO films were deposited on various orientations of single-crystal α-Al 2 O 3 . In this case, the reaction kinetics were studied and correlated with the interfacial structure (or substrate orientation). In the second, In 2 O 3 /MgO, solid-state reactions were studied under the influence of an electric field. The electric field provides a driving force for mass transport that affects both the reaction process and the morphological stability of an interface

  20. Chemical states of fission products in irradiated uranium-plutonium mixed oxide fuel

    International Nuclear Information System (INIS)

    Kurosaki, Ken; Uno, Masayoshi; Yamanaka, Shinsuke

    1999-01-01

    The chemical states of fission products (FPs) in irradiated uranium-plutonium mixed oxide (MOX) fuel for the light water reactor (LWR) were estimated by thermodynamic equilibrium calculations on system of fuel and FPs by using ChemSage program. A stoichiometric MOX containing 6.1 wt. percent PuO 2 was taken as a loading fuel. The variation of chemical states of FPs was calculated as a function of oxygen potential. Some pieces of information obtained by the calculation were compared with the results of the post-irradiation examination (PIE) of UO 2 fuel. It was confirmed that the multicomponent and multiphase thermodynamic equilibrium calculation between fuel and FPs system was an effective tool for understanding the behavior of FPs in fuel. (author)

  1. Origin of major donor states in In–Ga–Zn oxide

    Energy Technology Data Exchange (ETDEWEB)

    Nakashima, Motoki; Oota, Masashi; Ishihara, Noritaka; Nonaka, Yusuke; Hirohashi, Takuya; Takahashi, Masahiro; Yamazaki, Shunpei [Semiconductor Energy Laboratory Co., Ltd., 398 Hase, Atsugi, Kanagawa 243-0036 (Japan); Obonai, Toshimitsu; Hosaka, Yasuharu; Koezuka, Junichi [Advanced Film Device Inc., 161-2 Masuzuka, Tsuga-machi, Tochigi, Tochigi 328-0114 (Japan)

    2014-12-07

    To clarify the origin of the major donor states in indium gallium zinc oxide (IGZO), we report measurement results and an analysis of several physical properties of IGZO thin films. Specifically, the concentration of H atoms and O vacancies (V{sub O}), carrier concentration, and conductivity are investigated by hard X-ray photoelectron spectroscopy, secondary ion mass spectroscopy, thermal desorption spectroscopy, and Hall effect measurements. The results of these experiments suggest that the origin of major donor states is H occupancy of V{sub O} sites. Furthermore, we use first-principles calculations to investigate the influence of the coexistence of V{sub O} and H in crystalline InGaO{sub 3}(ZnO){sub m} (m = 1). The results indicate that when H is trapped in V{sub O}, a stable complex is created that serves as a shallow-level donor.

  2. Solid-State Electrochromic Device Consisting of Amorphous WO3 and Various Thin Oxide Layers

    Science.gov (United States)

    Shizukuishi, Makoto; Shimizu, Isamu; Inoue, Eiichi

    1980-11-01

    A mixed oxide containing Cr2O3 was introduced into an amorphous WO3 solid-state electrochromic device (ECD) in order to improve its colour memory effect. The electrochromic characteristics were greatly affected by the chemical constituents of a dielectric layer on the a-WO3 layer. Particularly, long memory effect and low power dissipation were attained in a solid-state ECD consisting of a-WO3 and Cr2O3\\cdotV2O5(50 wt.%). Some electrochromic characteristics of the a-WO3/Cr2O3\\cdotV2O5 ECD and the role of V2O5 were investigated.

  3. Long-living positron and positronium states in zeolites and microcrystalline oxides

    International Nuclear Information System (INIS)

    Kajcsos, Zs.; Liszkay, L.; Varga, L.; Lohonyai, L.; Lazar, K.

    1995-01-01

    Positron annihilation (PA) investigation were performed on zeolites (X, Y and ZSM-5) and on microcrystalline MgO, Al 2 O 3 and SiO 2 , providing long lifetime components attributed to o-Ps atoms. In addition to the positron lifetime (LT) measurements, the energy distribution (ED) of the annihilation gamma radiation spectrum was recorded in the 30 keV - 1.5 MeV range for different samples and was compared to reference distributions for Si and GaAs samples, where no long-living Ps states are formed. Apart from the strong correlation with the water content in the samples, the positron data collected testify much more pronounced positronium hosting features for powders of the mentioned oxides than for zeolites. Positron LT spectroscopy combined with recording of the ED of the annihilation radiation provides reliable information on the forming of long living 3γ states. (author) 15 refs.; 4 figs

  4. The state of itinerant charge carriers and thermoelectric effects in correlated oxide metals

    International Nuclear Information System (INIS)

    Kuzemsky, A.L.; Abdus Salam International Centre for Theoretical Physics, Trieste

    2000-10-01

    We analyzed the physics of transport processes and, in particular, the thermoelectric power in the mercurocuprates and other cuprates to get a better insight into the state of the carriers in these compounds. The actual problems related to the complicated mechanisms of carriers scattering above Tc are discussed. The experimental studies of thermoelectric power showed that the state of carriers in cuprates can be influenced by many complicated scattering processes, however the underlying mechanism for the linear decreasing of the TEP with increasing the temperature for most hole-doped HTSC cuprates is still not yet known. The actual problems related to the complicated mechanisms of carriers scattering above Tc are discussed for a few models of charge transport. A comparison between the analytical and experimental results is also made. It is concluded that the crucial factor for the understanding of the transport properties of correlated oxide metals is the nature of itinerant charge carriers, i.e. renormalized quasiparticles. (author)

  5. Probing the transition state region in catalytic CO oxidation on Ru

    Energy Technology Data Exchange (ETDEWEB)

    Ostrom, H. [Stockholm Univ. (Sweden); Oberg, H. [Stockholm Univ. (Sweden); Xin, H. [SLAC National Accelerator Lab., Menlo Park, CA (United States); LaRue, J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Beye, M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Helmholtz Zentrum Berlin fur Materialien und Energie GmbH, Berlin (Germany); Dell' Angela, M. [Univ. of Hamburg and Center for Free Electron Laser Science, Hamburg (Germany); Gladh, J. [Stockholm Univ. (Sweden); Ng, M. L. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Sellberg, J. A. [Stockholm Univ. (Sweden); SLAC National Accelerator Lab., Menlo Park, CA (United States); Kaya, S. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Mercurio, G. [Univ. of Hamburg and Center for Free Electron Laser Science, Hamburg (Germany); Nordlund, D. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Hantschmann, M. [Helmholtz Zentrum Berlin fur Materialien und Energie GmbH, Berlin (Germany); Hieke, F. [Univ. of Hamburg and Center for Free Electron Laser Science, Hamburg (Germany); Kuhn, D. [Helmholtz Zentrum Berlin fur Materialien und Energie GmbH, Berlin (Germany); Schlotter, W. F. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Dakovski, G. L. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Turner, J. J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Minitti, M. P. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Mitra, A. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Moeller, S. P. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Fohlisch, A. [Helmholtz Zentrum Berlin fur Materialien und Energie GmbH, Berlin (Germany); Univ. Potsdam, Potsdam (Germany); Wolf, M. [Fritz-Haber Institute of the Max-Planck-Society, Berlin (Germany); Wurth, W. [Univ. of Hamburg and Center for Free Electron Laser Science, Hamburg (Germany); DESY Photon Science, Hamburg (Germany); Persson, M. [The Univ. of Liverpool, Liverpool (United Kingdom); Norskov, J. K. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Abild-Pedersen, F. [Stanford Univ., Stanford, CA (United States); Ogasawara, H. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Pettersson, L. G. M. [Stockholm Univ. (Sweden); Nilsson, A. [Stockholm Univ. (Sweden); SLAC National Accelerator Lab., Menlo Park, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-02-12

    Femtosecond x-ray laser pulses are used to probe the CO oxidation reaction on ruthenium (Ru) initiated by an optical laser pulse. On a time scale of a few hundred femtoseconds, the optical laser pulse excites motions of CO and O on the surface, allowing the reactants to collide, and, with a transient close to a picosecond (ps), new electronic states appear in the O K-edge x-ray absorption spectrum. Density functional theory calculations indicate that these result from changes in the adsorption site and bond formation between CO and O with a distribution of OC–O bond lengths close to the transition state (TS). After 1 ps, 10% of the CO populate the TS region, which is consistent with predictions based on a quantum oscillator model.

  6. Oxidative stress markers in hypertensive states of pregnancy: preterm and term disease.

    Directory of Open Access Journals (Sweden)

    Lesia Olha Kurlak

    2014-08-01

    Full Text Available Discussion continues as to whether de novo hypertension in pregnancy with significant proteinuria (pre-eclampsia; PE and non-proteinuric new hypertension (gestational hypertension; GH are parts of the same disease spectrum or represent different conditions. Non-pregnant hypertension, pregnancy and PE are all associated with oxidative stress. We have established a 6 weeks post-partum clinic for women who experienced a hypertensive pregnancy. We hypothesized that PE and GH could be distinguished by markers of oxidative stress; thiobarbituric acid reactive substances (TBARS and antioxidants (ferric ion reducing ability of plasma; FRAP. Since the severity of PE and GH is greater pre-term, we also compared pre-term and term disease. Fifty-eight women had term PE, 23 pre-term PE, 60 had term GH and 6 pre-term GH, 11 pre-existing (essential hypertension (EH without PE. Limited data were available from normotensive pregnancies (n=7 and non-pregnant controls (n=14. There were no differences in postpartum TBARS or FRAP between hypertensive states; TBARS (P=0.001 and FRAP (P=0.009 were lower in plasma of non-pregnant controls compared to recently-pregnant women. Interestingly FRAP was higher in preterm than term GH (P=0.013. In PE and GH, TBARS correlated with low density lipoprotein (LDL-cholesterol (P=0.036; this association strengthened with inclusion of EH ((P=0.011. The 10 year Framingham index for cardiovascular risk was positively associated with TBARS (P=0.003.Oxidative stress profiles do not differ between hypertensive states but appear to distinguish between recently-pregnant and non-pregnant states. This suggests that pregnancy may alter vascular integrity with changes remaining 6 weeks postpartum. LDL-cholesterol is a known determinant of oxidative stress in cardiovascular disease and we have shown this association to be present in hypertensive pregnancy further emphasizing that such a pregnancy may be revealing a pre-existing cardiovascular

  7. Theoretical studies of positron states and annihilation characteristics at the oxidized Cu(100) surface

    Energy Technology Data Exchange (ETDEWEB)

    Fazleev, N. G. [Department of Physics, Box 19059, University of Texas at Arlington, Arlington Texas 76019 (United States) and Institute of Physics, Kazan Federal University, Kremlevskaya18, Kazan 420008 (Russian Federation); Weiss, A. H. [Department of Physics, Box 19059, University of Texas at Arlington, Arlington Texas 76019 (United States)

    2013-04-19

    In this work we present the results of theoretical studies of positron surface and bulk states and annihilation probabilities of surface-trapped positrons with relevant core electrons at the oxidized Cu(100) surface under conditions of high oxygen coverage. An ab-initio study of the electronic properties of the Cu(100) missing row reconstructed surface at various on surface and sub-surface oxygen coverages has been performed on the basis of the density functional theory (DFT) using the Dmol3 code and the generalized gradient approximation (GGA). Surface structures in calculations have been constructed by adding oxygen atoms to various surface hollow and sub-surface octahedral sites of the 0.5 monolayer (ML) missing row reconstructed phase of the Cu(100) surface with oxygen coverages ranging from 0.5 to 1.5 ML. The charge redistribution at the surface and variations in atomic structure and chemical composition of the topmost layers associated with oxidation and surface reconstruction have been found to affect the spatial extent and localization of the positron surface state wave function and annihilation probabilities of surface trapped positrons with relevant core electrons. Theoretical results are compared with experimental data obtained from studies of oxidation of the Cu(100) surface using positron annihilation induced Auger electron spectroscopy (PAES). It has been shown that positron annihilation probabilities with Cu 3s and 3p core electrons decrease when total (on-surface and sub-surface) oxygen coverage of the Cu(100) surface increases up to 1 ML. The calculations show that for high oxygen coverage when total oxygen coverage is 1. 5 ML the positron is not bound to the surface.

  8. Obesity-Associated Oxidative Stress: Strategies Finalized to Improve Redox State

    Directory of Open Access Journals (Sweden)

    Valeria Gasperi

    2013-05-01

    Full Text Available Obesity represents a major risk factor for a plethora of severe diseases, including diabetes, cardiovascular disease, non-alcoholic fatty liver disease, and cancer. It is often accompanied by an increased risk of mortality and, in the case of non-fatal health problems, the quality of life is impaired because of associated conditions, including sleep apnea, respiratory problems, osteoarthritis, and infertility. Recent evidence suggests that oxidative stress may be the mechanistic link between obesity and related complications. In obese patients, antioxidant defenses are lower than normal weight counterparts and their levels inversely correlate with central adiposity; obesity is also characterized by enhanced levels of reactive oxygen or nitrogen species. Inadequacy of antioxidant defenses probably relies on different factors: obese individuals may have a lower intake of antioxidant- and phytochemical-rich foods, such as fruits, vegetables, and legumes; otherwise, consumption of antioxidant nutrients is normal, but obese individuals may have an increased utilization of these molecules, likewise to that reported in diabetic patients and smokers. Also inadequate physical activity may account for a decreased antioxidant state. In this review, we describe current concepts in the meaning of obesity as a state of chronic oxidative stress and the potential interventions to improve redox balance.

  9. Obesity-Associated Oxidative Stress: Strategies Finalized to Improve Redox State

    Science.gov (United States)

    Savini, Isabella; Catani, Maria Valeria; Evangelista, Daniela; Gasperi, Valeria; Avigliano, Luciana

    2013-01-01

    Obesity represents a major risk factor for a plethora of severe diseases, including diabetes, cardiovascular disease, non-alcoholic fatty liver disease, and cancer. It is often accompanied by an increased risk of mortality and, in the case of non-fatal health problems, the quality of life is impaired because of associated conditions, including sleep apnea, respiratory problems, osteoarthritis, and infertility. Recent evidence suggests that oxidative stress may be the mechanistic link between obesity and related complications. In obese patients, antioxidant defenses are lower than normal weight counterparts and their levels inversely correlate with central adiposity; obesity is also characterized by enhanced levels of reactive oxygen or nitrogen species. Inadequacy of antioxidant defenses probably relies on different factors: obese individuals may have a lower intake of antioxidant- and phytochemical-rich foods, such as fruits, vegetables, and legumes; otherwise, consumption of antioxidant nutrients is normal, but obese individuals may have an increased utilization of these molecules, likewise to that reported in diabetic patients and smokers. Also inadequate physical activity may account for a decreased antioxidant state. In this review, we describe current concepts in the meaning of obesity as a state of chronic oxidative stress and the potential interventions to improve redox balance. PMID:23698776

  10. Oxidation state of sulfur, iron and tin at the surface of float glasses

    International Nuclear Information System (INIS)

    Lagarde, P; Flank, A-M; Jupille, J; Montigaud, H

    2009-01-01

    Sulfur is an important element of glasses, not because of its amount, always very low (less than 0.4 % in weight of SO 3 ), but because of its role since it actively participates to the refinement process and, combined to other elements, it can be responsible for the coloration of the glass. Iron is also of a major importance in most of the glasses. In the case of the float glass, the two faces, because of the fabrication process, are different in terms of composition (presence of Sn for one face) and also in terms of oxidation state of these minority elements (Fe, Sn, S). There should be a subtle interplay between the concentrations and the oxidation states of these different minority elements, and anyway these variations occur over a thickness of the order of few micrometers below the surface. Using the high intensity and the focusing properties (3 x 3 μm 2 ) of the x-ray beam from the Lucia beamline, we have therefore studied the speciation of iron and sulfur near the face of a float glass in relation with the behavior of tin. This has been obtained by combining elemental x-ray fluorescence cartography and x-ray micro-absorption at the different K-edges.

  11. Oxidation state of sulfur, iron and tin at the surface of float glasses

    Energy Technology Data Exchange (ETDEWEB)

    Lagarde, P; Flank, A-M [Synchrotron SOLEIL, l' Orme des Merisiers, BP 48 91192 Gif/Yvette cedex (France); Jupille, J [IMPMC, Universite P. and M. Curie, Campus de Boucicaut, 140 rue de Lourmel 75015 Paris (France); Montigaud, H [Saint-Gobain Recherche 39, quai Lucien Lefranc, BP 135 93303 Aubervilliers Cedex (France)

    2009-11-15

    Sulfur is an important element of glasses, not because of its amount, always very low (less than 0.4 % in weight of SO{sub 3}), but because of its role since it actively participates to the refinement process and, combined to other elements, it can be responsible for the coloration of the glass. Iron is also of a major importance in most of the glasses. In the case of the float glass, the two faces, because of the fabrication process, are different in terms of composition (presence of Sn for one face) and also in terms of oxidation state of these minority elements (Fe, Sn, S). There should be a subtle interplay between the concentrations and the oxidation states of these different minority elements, and anyway these variations occur over a thickness of the order of few micrometers below the surface. Using the high intensity and the focusing properties (3 x 3 {mu}m{sup 2}) of the x-ray beam from the Lucia beamline, we have therefore studied the speciation of iron and sulfur near the face of a float glass in relation with the behavior of tin. This has been obtained by combining elemental x-ray fluorescence cartography and x-ray micro-absorption at the different K-edges.

  12. Towards the improvement of the oxidation resistance of Nb-silicides in situ composites: A solid state diffusion approach

    International Nuclear Information System (INIS)

    Mathieu, S.; Knittel, S.; François, M.; Portebois, L.; Mathieu, S.; Vilasi, M.

    2014-01-01

    Highlights: •Local equilibrium is attained during oxidation at phase boundaries (steady state conditions). •A solid state diffusion model explains the oxidation mechanism of Nb-silicides composites. •The Nb ss fraction is not the only parameters governing the oxidation rate of Nb-silicides. •Aluminium increases the thermodynamic activity of Si in the Nb-silicides composites. •The results indicate the need to develop a Nb–Ti–Hf–Al–Cr–Si thermodynamic database. -- Abstract: The present study focuses on the oxidation mechanism of Nb-silicide composites and on the effect of the composition on the oxidation rate at 1100 °C. A theoretical approach is proposed based on experimental results and used to optimise the oxidation resistance. The growth model based on multiphase diffusion was experimentally tested and confirmed by manufacturing seven composites with different compositions. It was also found that the effect of the composition has to be evaluated at 1100 °C within a short time duration (50 h), where the oxide scale and the internal oxidation zone both grow according to parabolic kinetics

  13. Effect of surface state on the oxidation behavior of welded 308L in simulated nominal primary water of PWR

    Science.gov (United States)

    Ming, Hongliang; Zhang, Zhiming; Wang, Jiazhen; Zhu, Ruolin; Ding, Jie; Wang, Jianqiu; Han, En-Hou; Ke, Wei

    2015-05-01

    The oxidation behavior of 308L weld metal (WM) with different surface state in the simulated nominal primary water of pressurized water reactor (PWR) was studied by scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) analyzer and X-ray photoelectron spectroscopy (XPS). After 480 h immersion, a duplex oxide film composed of a Fe-rich outer layer (Fe3O4, Fe2O3 and a small amount of NiFe2O4, Ni(OH)2, Cr(OH)3 and (Ni, Fe)Cr2O4) and a Cr-rich inner layer (FeCr2O4 and NiCr2O4) can be formed on the 308L WM samples with different surface state. The surface state has no influence on the phase composition of the oxide films but obviously affects the thickness of the oxide films and the morphology of the oxides (number & size). With increasing the density of dislocations and subgrain boundaries in the cold-worked superficial layer, the thickness of the oxide film, the number and size of the oxides decrease.

  14. Cellulose nanofibril/reduced graphene oxide/carbon nanotube hybrid aerogels for highly flexible and all-solid-state supercapacitors

    Science.gov (United States)

    Qifeng Zheng; Zhiyong Cai; Zhenqiang Ma; Shaoqin Gong

    2015-01-01

    A novel type of highly flexible and all-solid-state supercapacitor that uses cellulose nanofibril (CNF)/reduced graphene oxide (RGO)/carbon nanotube (CNT) hybrid aerogels as electrodes and H2SO4 poly (vinyl alcohol) PVA gel as the electrolyte was developed and is reported here. These flexible solid-state supercapacitors...

  15. Moessbauer effect study of oxidation and coordination states of iron in some sodium borate glasse:;

    International Nuclear Information System (INIS)

    Eissa, N.A.; Sanad, A.M.; Youssef, S.M.; El-Henawii, S.A.; Gomaa, S.Sh.; Mostafa, A.G.

    1980-01-01

    A structural study of some sodium borate glasses containing iron was carried out applying ME spectroscopy. Both oxidation and coordination states of iron were investigated under the effect of gradual replacing of sodium carbonate by sodium nitrate in the glass batches. The glasses were melted in porcelain crucibles using an electrically heated furnace at 1000+-10 deg C, then were quenched on a steel plate at room temperature (R.T.). The ME source was 20 mCi radioactive Co-57 in chromium. The obtained ME spectra indicated that at lower sodium nitrate content both Fe 2+ and Fe 3+ are present in these glasses. At moderate concentrations some Fe 3+ ions were separated in a crystalline phase and the rest of the iron ions appeared as ferric ions in glassy state. At high sodium nitrate content only Fe 3+ ions in glassy state were detected. The values of the ME parameters for all iron ions indicated that all of them are in the octahedral coordination state. The density measurements confirm the separation of a crystalline phase at moderate sodium nitrate content. (author)

  16. Quantum State-Resolved Collision Dynamics of Nitric Oxide at Ionic Liquid and Molten Metal Surfaces

    Science.gov (United States)

    Zutz, Amelia Marie

    Detailed molecular scale interactions at the gas-liquid interface are explored with quantum state-to-state resolved scattering of a jet-cooled beam of NO(2pi1/2; N = 0) from ionic liquid and molten metal surfaces. The scattered distributions are probed via laser-induced fluorescence methods, which yield rotational and spin-orbit state populations that elucidate the dynamics of energy transfer at the gas-liquid interface. These collision dynamics are explored as a function of incident collision energy, surface temperature, scattering angle, and liquid identity, all of which are found to substantially affect the degree of rotational, electronic and vibrational excitation of NO via collisions at the liquid surface. Rotational distributions observed reveal two distinct scattering pathways, (i) molecules that trap, thermalize and eventually desorb from the surface (trapping-desorption, TD), and (ii) those that undergo prompt recoil (impulsive scattering, IS) prior to complete equilibration with the liquid surface. Thermally desorbing NO molecules are found to have rotational temperatures close to, but slightly cooler than the surface temperature, indicative of rotational dependent sticking probabilities on liquid surfaces. Nitric oxide is a radical with multiple low-lying electronic states that serves as an ideal candidate for exploring nonadiabatic state-changing collision dynamics at the gas-liquid interface, which induce significant excitation from ground (2pi1/2) to excited (2pi 3/2) spin-orbit states. Molecular beam scattering of supersonically cooled NO from hot molten metals (Ga and Au, Ts = 300 - 1400 K) is also explored, which provide preliminary evidence for vibrational excitation of NO mediated by thermally populated electron-hole pairs in the hot, conducting liquid metals. The results highlight the presence of electronically nonadiabatic effects and build toward a more complete characterization of energy transfer dynamics at gas-liquid interfaces.

  17. Origin of stabilization and destabilization in solid-state redox reaction of oxide ions for lithium-ion batteries.

    Science.gov (United States)

    Yabuuchi, Naoaki; Nakayama, Masanobu; Takeuchi, Mitsue; Komaba, Shinichi; Hashimoto, Yu; Mukai, Takahiro; Shiiba, Hiromasa; Sato, Kei; Kobayashi, Yuki; Nakao, Aiko; Yonemura, Masao; Yamanaka, Keisuke; Mitsuhara, Kei; Ohta, Toshiaki

    2016-12-23

    Further increase in energy density of lithium batteries is needed for zero emission vehicles. However, energy density is restricted by unavoidable theoretical limits for positive electrodes used in commercial applications. One possibility towards energy densities exceeding these limits is to utilize anion (oxide ion) redox, instead of classical transition metal redox. Nevertheless, origin of activation of the oxide ion and its stabilization mechanism are not fully understood. Here we demonstrate that the suppression of formation of superoxide-like species on lithium extraction results in reversible redox for oxide ions, which is stabilized by the presence of relatively less covalent character of Mn 4+ with oxide ions without the sacrifice of electronic conductivity. On the basis of these findings, we report an electrode material, whose metallic constituents consist only of 3d transition metal elements. The material delivers a reversible capacity of 300 mAh g -1 based on solid-state redox reaction of oxide ions.

  18. Origin of stabilization and destabilization in solid-state redox reaction of oxide ions for lithium-ion batteries

    Science.gov (United States)

    Yabuuchi, Naoaki; Nakayama, Masanobu; Takeuchi, Mitsue; Komaba, Shinichi; Hashimoto, Yu; Mukai, Takahiro; Shiiba, Hiromasa; Sato, Kei; Kobayashi, Yuki; Nakao, Aiko; Yonemura, Masao; Yamanaka, Keisuke; Mitsuhara, Kei; Ohta, Toshiaki

    2016-01-01

    Further increase in energy density of lithium batteries is needed for zero emission vehicles. However, energy density is restricted by unavoidable theoretical limits for positive electrodes used in commercial applications. One possibility towards energy densities exceeding these limits is to utilize anion (oxide ion) redox, instead of classical transition metal redox. Nevertheless, origin of activation of the oxide ion and its stabilization mechanism are not fully understood. Here we demonstrate that the suppression of formation of superoxide-like species on lithium extraction results in reversible redox for oxide ions, which is stabilized by the presence of relatively less covalent character of Mn4+ with oxide ions without the sacrifice of electronic conductivity. On the basis of these findings, we report an electrode material, whose metallic constituents consist only of 3d transition metal elements. The material delivers a reversible capacity of 300 mAh g−1 based on solid-state redox reaction of oxide ions. PMID:28008955

  19. Role of the oxidation state of cerium on the ceria surfaces for silicate adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Jihoon [WCD Department of Energy Engineering, Hanyang University, Seoul (Korea, Republic of); Moon, Jinok [WCD Department of Energy Engineering, Hanyang University, Seoul (Korea, Republic of); Clean/CMP Technology Team, Memory, Samsung Electronics, Hwaseong (Korea, Republic of); Kim, Joo Hyun; Lee, Kangchun [WCD Department of Energy Engineering, Hanyang University, Seoul (Korea, Republic of); Hwang, Junha [WCD Department of Energy Engineering, Hanyang University, Seoul (Korea, Republic of); Materials R& D Center, K.C.Tech, Anseong (Korea, Republic of); Yoon, Heesung [WCD Department of Energy Engineering, Hanyang University, Seoul (Korea, Republic of); Yi, Dong Kee, E-mail: vitalis@mju.ac.kr [Department of Chemistry, Myongji University, Yongin (Korea, Republic of); Paik, Ungyu, E-mail: upaik@hanyang.ac.kr [WCD Department of Energy Engineering, Hanyang University, Seoul (Korea, Republic of)

    2016-12-15

    Highlights: • We investigated the role of Ce oxidation state (Ce{sup 3+}/Ce{sup 4+}) on the CeO{sub 2} surfaces for the silicate adsorption. • As the Ce{sup 3+} concentration increased from 19.3 to 27.6%, the surface density of −OH group increased from 0.34 to 0.72 OH/nm{sup 2}. • The Freundlich constant for the relative adsorption capacity (K{sub F}) and adsorption intensity (1/n) indicated that CeO{sub 2} NPs with high Ce{sup 3+} concentration show higher adsorption affinity with silicate ions. - Abstract: In this study, we have investigated the role of the Ce oxidation state (Ce{sup 3+}/Ce{sup 4+}) on the CeO{sub 2} surfaces for silicate adsorption. In aqueous medium, the Ce{sup 3+} sites lead to the formation of −OH groups at the CeO{sub 2} surface through H{sub 2}O dissociation. Silicate ions can adsorb onto the CeO{sub 2} surface through interaction with the −OH groups (−Ce−OH− + −Si−O{sup −} ↔ −Ce−O−Si− + OH{sup −}). As the Ce{sup 3+} concentration increased from 19.3 to 27.6%, the surface density of −OH group increased from 0.34 to 0.72 OH/nm{sup 2}. To evaluate the adsorption behaviors of silicate ions onto CeO{sub 2} NPs, we carried out an adsorption isothermal analysis, and the adsorption isotherm data followed the Freundlich model. The Freundlich constant for the relative adsorption capacity (K{sub F}) and adsorption intensity (1/n) indicated that CeO{sub 2} NPs with high Ce{sup 3+} concentration show higher adsorption affinity with silicate ions. As a result, we have demonstrated that the Ce oxidation state (Ce{sup 3+}/Ce{sup 4+}) on the CeO{sub 2} surface can have a significant influence on the silicate adsorption.

  20. Electronic state of ruthenium deposited onto oxide supports: An XPS study taking into account the final state effects

    International Nuclear Information System (INIS)

    Larichev, Yurii V.; Moroz, Boris L.; Bukhtiyarov, Valerii I.

    2011-01-01

    The electronic state of ruthenium in the supported Ru/EO x (EO x = MgO, Al 2 O 3 or SiO 2 ) catalysts prepared by with the use of Ru(OH)Cl 3 or Ru(acac) 3 (acac = acetylacetonate) and reduced with H 2 at 723 K is characterized by X-ray photoelectron spectroscopy (XPS) in the Ru 3d, Cl 2p and O 1s regions. The influence of the final state effects (the differential charging and variation of the relaxation energy) on the binding energy (BE) of Ru 3d 5/2 core level measured for supported Ru nanoparticles is estimated by comparison of the Fermi levels and the modified Auger parameters determined for the Ru/EO x samples with the corresponding characteristics of the bulk Ru metal. It is found that the negative shift of the Ru 3d 5/2 peak which is observed in the spectrum of ruthenium deposited onto MgO (BE = 279.5-279.7 eV) with respect to that of Ru black (BE = 280.2 eV) or ruthenium supported on γ-Al 2 O 3 and SiO 2 (BE = 280.4 eV) is caused not by the transfer of electron density from basic sites of MgO, as considered earlier, but by the differential charging of the supported Ru particles compared with the support surface. Correction for the differential charging value reveals that the initial state energies of ruthenium in the Ru/EO x systems are almost identical (BE = 280.5 ± 0.1 eV) irrespectively of acid-base properties of the support, the mean size of supported Ru crystallites (within the range of 2-10 nm) and the surface Cl content. The results obtained suggest that the difference in ammonia synthesis activity between the Ru catalysts supported on MgO and on the acidic supports is accounted for by not different electronic state of ruthenium on the surface of these oxides but by some other reasons.

  1. Solid-state ionics: Studies of lithium-conducting sulfide glasses and a superconducting oxide compound

    International Nuclear Information System (INIS)

    Ahn, Byung Tae.

    1989-01-01

    The first part of this work studies lithium-conducting sulfide glasses for battery applications, while the second part studies the thermodynamic properties of a superconducting oxide compound by using an oxide electrolyte. Lithium conducting glasses based on the SiS 2 -Li 2 S system are possible solid electrolytes for high-energy-density lithium batteries. The foremost requirement for solid electrolytes is that they should have high ionic conductivities. Unfortunately, most crystalline lithium conductors have low ionic conductivities at room temperature. However, glass ionic conductors show higher ionic conductivities than do crystalline forms of the same material. In addition to higher ionic conductivities, glasses appear to have several advantages over crystalline materials. These advantages include isotropic conductivity, absence of grain boundary effects, ease of glass forming, and the potential for a wide range of stability to oxidizing and reducing conditions. Using pyrolitic graphite-coated quartz ampoules, new ternary compounds and glasses in the SiS 2 -Li 2 S system were prepared. Several techniques were used to characterize the materials: powder x-ray diffraction, differential thermal analysis, differential scanning calorimetry, and AC impedance spectroscopy. The measured lithium conductivity of the sulfide glasses was one of the highest among the known solid lithium conductors. Measuring the equilibrium open circuit voltages assisted in determining the electrochemical stabilities of the ternary compounds and glasses with respect to pure Li. A solid-state ionic technique called oxygen coulometric titration was used to measure the thermodynamic stability, the oxygen stoichiometry, and the effects of the oxygen stoichiometry, and the effects of the oxygen stoichiometry and the cooling rate on superconductivity of the YBa 2 Cu 3 O 7-x compound were investigated

  2. Effect of charge state and stoichiometry on the structure and reactivity of nickel oxide clusters with CO

    Science.gov (United States)

    Johnson, Grant E.; Reilly, Nelly M.; Castleman, A. W., Jr.

    2009-02-01

    The collision induced fragmentation and reactivity of cationic and anionic nickel oxide clusters with carbon monoxide were studied experimentally using guided-ion-beam mass spectrometry. Anionic clusters with a stoichiometry containing one more oxygen atom than nickel atom (NiO2-, Ni2O3-, Ni3O4- and Ni4O5-) were found to exhibit dominant products resulting from the transfer of a single oxygen atom to CO, suggesting the formation of CO2. Of these four species, Ni2O3- and Ni4O5- were observed to be the most reactive having oxygen transfer products accounting for approximately 5% and 10% of the total ion intensity at a maximum pressure of 15 mTorr of CO. Our findings, therefore, indicate that anionic nickel oxide clusters containing an even number of nickel atoms and an odd number of oxygen atoms are more reactive than those with an odd number of nickel atoms and an even number of oxygen atoms. The majority of cationic nickel oxides, in contrast to anionic species, reacted preferentially through the adsorption of CO onto the cluster accompanied by the loss of either molecular O2 or nickel oxide units. The adsorption of CO onto positively charged nickel oxides, therefore, is exothermic enough to break apart the gas-phase clusters. Collision induced dissociation experiments, employing inert xenon gas, were also conducted to gain insight into the structural properties of nickel oxide clusters. The fragmentation products were found to vary considerably with size and stoichiometry as well as ionic charge state. In general, cationic clusters favored the collisional loss of molecular O2 while anionic clusters fragmented through the loss of both atomic oxygen and nickel oxide units. Our results provide insight into the effect of ionic charge state on the structure of nickel oxide clusters. Furthermore, we establish how the size and stoichiometry of nickel oxide clusters influences their ability to oxidize CO, an important reaction for environmental pollution abatement.

  3. Remote Sensing the Thermosphere's State Using Emissions From Carbon Dioxide and Nitric Oxide

    Science.gov (United States)

    Weimer, D. R.; Mlynczak, M. G.; Doornbos, E.

    2017-12-01

    Measurements of emissions from nitric oxide and carbon dioxide in the thermosphere have strong correlations with properties that are very useful to the determination of thermospheric densities. We have compared emissions measured with the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite with neutral density measurements from the Challenging Mini-satellite Payload (CHAMP), the Gravity Recovery and Climate Experiment (GRACE), the Ocean Circulation Explorer (GOCE), and the three Swarm satellites, spanning a time period of over 15 years. It has been found that nitric oxide emissions match changes in the exospheric temperatures that have been derived from the densities through use of the Naval Reasearch Laboratory Mass Spectrometer, Incoherent Scatter Radar Extended Model (NRLMSISE-00) thermosphere model. Similarly, our results indicate that the carbon dioxide emissions have annual and semiannual oscillations that correlate with changes in the amount of oxygen in the thermosphere, also determined by use of the NRLMSISE-00 model. These annual and semi-annual variations are found to have irregular amplitudes and phases, which make them very difficult to accurately predict. Prediction of exospheric temperatures through the use of geomagnetic indices also tends to be inexact. Therefore, it would be possible and very useful to use measurements of the thermosphere's infrared emissions for real-time tracking of the thermosphere's state, so that more accurate calculations of the density may be obtained.

  4. Solid State Energy Conversion Alliance (SECA) Solid Oxide Fuel Cell Program

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen Minh

    2006-07-31

    This report summarizes the work performed for Phase I (October 2001 - August 2006) under Cooperative Agreement DE-FC26-01NT41245 for the U. S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled 'Solid State Energy Conversion Alliance (SECA) Solid Oxide Fuel Cell Program'. The program focuses on the development of a low-cost, high-performance 3-to-10-kW solid oxide fuel cell (SOFC) system suitable for a broad spectrum of power-generation applications. During Phase I of the program significant progress has been made in the area of SOFC technology. A high-efficiency low-cost system was designed and supporting technology developed such as fuel processing, controls, thermal management, and power electronics. Phase I culminated in the successful demonstration of a prototype system that achieved a peak efficiency of 41%, a high-volume cost of $724/kW, a peak power of 5.4 kW, and a degradation rate of 1.8% per 500 hours. . An improved prototype system was designed, assembled, and delivered to DOE/NETL at the end of the program. This prototype achieved an extraordinary peak efficiency of 49.6%.

  5. Determination of oxidation state of iron in normal and pathologically altered human aortic valves

    Energy Technology Data Exchange (ETDEWEB)

    Czapla-Masztafiak, J. [Institute of Nuclear Physics PAN, Radzikowskiego 152, 31-342 Kraków (Poland); Lis, G.J.; Gajda, M.; Jasek, E. [Department of Histology, Jagiellonian University Medical College, Kopernika 7, 31-034 Kraków (Poland); Czubek, U. [Department of Coronary Disease, Jagiellonian University Medical College, John Paul II Hospital, Prądnicka 80, 31-202 Kraków (Poland); Bolechała, F. [Department of Forensic Medicine, Jagiellonian University Medical College, Grzegórzecka 16, 31-531 Kraków (Poland); Borca, C. [Swiss Light Source, Paul Scherrer Institute, 5232 Villigen PSI (Switzerland); Kwiatek, W.M. [Institute of Nuclear Physics PAN, Radzikowskiego 152, 31-342 Kraków (Poland)

    2015-12-01

    In order to investigate changes in chemical state of iron in normal and pathologically altered human aortic valves X-ray absorption spectroscopy was applied. Since Fe is suspected to play detrimental role in aortic valve stenosis pathogenesis the oxidation state of this element has been determined. The experimental material consisted of 10 μm sections of valves excised during routine surgery and from autopsies. The experiment was performed at the MicroXAS beamline of the SLS synchrotron facility in Villigen (Switzerland). The Fe K-edge XANES spectra obtained from tissue samples were carefully analyzed and compared with the spectra of reference compounds containing iron in various chemical structures. The analysis of absorption edge position and shape of the spectra revealed that both chemical forms of iron are presented in valve tissue but Fe{sup 3+} is the predominant form. Small shift of the absorption edge toward higher energy in the spectra from stenotic valve samples indicates higher content of the Fe{sup 3+} form in pathological tissue. Such a phenomenon suggests the role of Fenton reaction and reactive oxygen species in the etiology of aortic valve stenosis. The comparison of pre-edge regions of XANES spectra for control and stenotic valve tissue confirmed no differences in local symmetry or spin state of iron in analyzed samples.

  6. The effect of cerium valence states at cerium oxide nanoparticle surfaces on cell proliferation

    KAUST Repository

    Naganuma, Tamaki

    2014-05-01

    Understanding and controlling cell proliferation on biomaterial surfaces is critical for scaffold/artificial-niche design in tissue engineering. The mechanism by which underlying integrin ligates with functionalized biomaterials to induce cell proliferation is still not completely understood. In this study, poly-l-lactide (PL) scaffold surfaces were functionalized using layers of cerium oxide nanoparticles (CNPs), which have recently attracted attention for use in therapeutic application due to their catalytic ability of Ce4+ and Ce3+ sites. To isolate the influence of Ce valance states of CNPs on cell proliferation, human mesenchymal stem cells (hMSCs) and osteoblast-like cells (MG63) were cultured on the PL/CNP surfaces with dominant Ce4+ and Ce3+ regions. Despite cell type (hMSCs and MG63 cells), different surface features of Ce4+ and Ce3+ regions clearly promoted and inhibited cell spreading, migration and adhesion behavior, resulting in rapid and slow cell proliferation, respectively. Cell proliferation results of various modified CNPs with different surface charge and hydrophobicity/hydrophilicity, indicate that Ce valence states closely correlated with the specific cell morphologies and cell-material interactions that trigger cell proliferation. This finding suggests that the cell-material interactions, which influence cell proliferation, may be controlled by introduction of metal elements with different valence states onto the biomaterial surface. © 2014 Elsevier Ltd.

  7. Investigating the capability of ToF-SIMS to determine the oxidation state of Ce

    Science.gov (United States)

    Seed Ahmed, H. A. A.; Swart, H. C.; Kroon, R. E.

    2018-04-01

    The capability of time of flight secondary ion mass spectrometry (ToF-SIMS) to determine the oxidation state of Ce ions doped in a phosphor was investigated. Two samples of SiO2:Ce (4 mol%) with known Ce3+/Ce4+ relative concentrations were subjected to ToF-SIMS measurements. The spectra were very similar and no significant differences in the relative peak intensities were observed that would readily allow one to distinguish Ce3+ from Ce4+. Although ToF-SIMS was therefore not useful to distinguish the charge state of Ce ions doped in this phosphor material, the idea in principle was also tested on two other samples, namely CeF3 and CeF4 These contain Ce as part of the host (i.e. much higher concentration) and are fluorides, which is significant because ToF-SIMS has previously been reported to be able to distinguish Eu2+ from Eu3+ in Eu doped Sr5(PO4)3F phosphor. The spectrum of CeF4 contained a small peak related to Ce4+ which was not observed in the CeF3 spectrum, yet the peak related to the Ce3+ ions was found to be much more intense in the spectrum of CeF4 than CeF3, showing that the ToF-SIMS signals cannot be directly interpreted as retaining the charge state of the ions in the original material. Nevertheless, the significant differences in the Ce-related peaks in the ToF-SIMS spectra from CeF3 and CeF4 show that the charge state of Ce may be distinguished. This study shows that while in principle ToF-SIMS may be used to distinguish the charge state of Ce ions, this depends on the sample and it would not be easy to interpret the spectra without a standard or reference.

  8. Coherent diffractive imaging of solid state reactions in zinc oxide crystals

    Science.gov (United States)

    Leake, Steven J.; Harder, Ross; Robinson, Ian K.

    2011-11-01

    We investigated the doping of zinc oxide (ZnO) microcrystals with iron and nickel via in situ coherent x-ray diffractive imaging (CXDI) in vacuum. Evaporated thin metal films were deposited onto the ZnO microcrystals. A single crystal was selected and tracked through annealing cycles. A solid state reaction was observed in both iron and nickel experiments using CXDI. A combination of the shrink wrap and guided hybrid-input-output phasing methods were applied to retrieve the electron density. The resolution was 33 nm (half order) determined via the phase retrieval transfer function. The resulting images are nevertheless sensitive to sub-angstrom displacements. The exterior of the microcrystal was found to degrade dramatically. The annealing of ZnO microcrystals coated with metal thin films proved an unsuitable doping method. In addition the observed defect structure of one crystal was attributed to the presence of an array of defects and was found to change upon annealing.

  9. Oxidation-state distribution of plutonium in surface and subsurface waters at Thule, northwest Greenland

    DEFF Research Database (Denmark)

    McMahon, C.A.; Vintró, L.L.; Mitchell, P.I.

    2000-01-01

    (V, VI) (mean, 68 +/- 6%; n = 6), with little if any distinction apparent between surface and bottom waters. Further, the oxidation state distribution at stations close to the accident site is similar to that measured at Upernavik, remote from this site. It is also similar to the distribution observed...... in shelf waters at midlatitudes, suggesting that the underlying processes controlling plutonium speciation are insensitive to temperature over the range 0-25 degrees C. Measurements using tangential-flow ultrafiltration indicate that virtually all of the plutonium (including the fraction in a reduced...... chemical form) is present as fully dissolved species. Most of this plutonium would seem to be of weapons fallout origin, as the mean Pu-238/Pu-239,Pu-240 activity ratio in the water column (dissolved phase) at Thule (0.06 +/- 0.02; n = 10) is similar to the global fallout ratio at this latitude...

  10. State-of-the-art technologies of gallium oxide power devices

    Science.gov (United States)

    Higashiwaki, Masataka; Kuramata, Akito; Murakami, Hisashi; Kumagai, Yoshinao

    2017-08-01

    Gallium oxide (Ga2 O3 ) has gained increased attention for power devices due to its superior material properties and the availability of economical device-quality native substrates. This review illustrates recent advances in Ga2 O3 device technologies, beginning with an overview of the social circumstances that motivate the development of new-generation switching devices. Following an introduction to the material properties of Ga2 O3 from the viewpoint of power electronics, growth technologies of Ga2 O3 bulk single crystals and epitaxial thin films are discussed. The fabrication and performance of state-of-the-art Ga2 O3 transistors and diodes are then described. We conclude by identifying the directions and challenges of Ga2 O3 power device development in the near future.

  11. Coordination and Oxidation States of Iron Incorporated in Mesoporous MCM41

    International Nuclear Information System (INIS)

    Lazar, K.; Pal-Borbely, G.; Szegedi, A.; Beyer, H. K.

    2002-01-01

    Mesoporous Fe-MCM41 samples (Si/Fe=25) were synthesized and characterized under evacuation and reducing/oxidizing treatments by in situ FTIR and Moessbauer spectroscopies. Both Fe(II) and Fe(III) located in low coordination states in top layers of pore walls exhibit Lewis acidity and may participate in Fe(III) ↔ Fe(II) processes at low temperatures (570 K). Furthermore, Fe(III) ↔ Fe(II) cycles can be achieved and repeated with participation of the full amount of iron at higher temperatures (670 K). The accompanying formation of oxygen vacancies and restoration of the structure in the reverse process does not result in extended damages; the MCM41 structure retains its stability under the conditions applied.

  12. Oxidation State of Iron in the Izu-Bonin Arc Initial Magma and Its Influence Factors

    Science.gov (United States)

    Li, H.; Arculus, R. J.; Brandl, P. A.; Hamada, M.; Savov, I. P.; Zhu, S.; Hickey-Vargas, R.; Tepley, F. J., III; Meffre, S.; Yogodzinski, G. M.; McCarthy, A.; Barth, A. P.; Kanayama, K.; Kusano, Y.; Sun, W.

    2014-12-01

    The redox state of mantle-derived magmas is a controversial issue, especially whether island arc basalts are more oxidized than those from mid-ocean ridges. Usually, arc magmas have higher Fe3+/Fe2+ and calculated oxygen fugacity (fO2) than mid-ocean ridge basalts (MORB). It is the high fO2 of arc magma that apparently delays onset of sulfide fractionation and sequestration of precious/base metals thereby facilitating the formation of many giant gold-copper deposits typically associated with subduction zones. But due to a paucity of Fe3+/Fe2+ data for primary mantle-derived arc magmas, the cause for high fO2 of these magma types is still controversial; causes may include inter alia subduction-released oxidized material addition to the mantle wedge source of arc magma, partial melting of subducted slab, and redox changes occurring during ascent of the magma. Fortunately, IODP expedition 351 drilling at IODP Site U1438 in the Amami-Sankaku Basin of the northwestern Philipine Sea, adjacent to the proto-Izu-Bonin Arc at the Kyushu-Palau Ridge (KPR), recovered not only volcaniclastics derived from the inception of Izu-Bonin Mariana (IBM) arc in the Eocene, but also similar materials for the Arc's subsequent evolution through to the Late Oligocene and abandonment of the KPR as a remnant arc. Samples of the pre-Arc oceanic crustal basement were also recovered enabling us to determine the fO2of the mantle preceding arc inception. As the oxidation state of iron in basaltic glass directly relates to the fO2 , the Fe3+/∑Fe ratio [Fe3+/(Fe3++ Fe2+)] of basaltic glass are quantified by synchrotron-facilitated micro X-ray Absorption Near Edge Structure (XANES) spectroscopy to reflect its fO2. Fe K-edge µ-XANES spectra were recorded in fluorescence mode at Beamline 15U1, Shanghai Synchrotron Radiation Facility (SSRF). Synthetic silicate glass with known Fe3+/∑Fe ratio was used in data handling. The experimental results as well as preliminary data from IODP Expedition 351

  13. The oxidation state of Fe in glasses from the Kerguelen Large Igneous Province: Evidence for the changing oxidation state of the Indian Ocean Basin

    Science.gov (United States)

    Peterson, M. E.; Stolper, E.; Brounce, M. N.; Eiler, J. M.; Wallace, P. J.

    2017-12-01

    Oxygen fugacity (ƒO2) is a thermodynamic property of silicate magmas that can be influenced by volcanic processes such as melting, crystal fractionation, and degassing. Lavas erupted as part of large igneous provinces (LIPs) may reflect the impingement of mantle plumes on the lithosphere, and thus could provide constraints on the ƒO2 of plumes responsible for generation of LIPs. The Kerguelen plateau was emplaced during the break up of Gondwana and the initial opening of the Indian Ocean. Elevated 207Pb/204Pb and 208Pb/204Pb ratios at low 206Pb/204Pb suggests that continental lithosphere from Gondwana is present in the asthenosphere of this region. The Sr-Nd-Pb-He isotopic compositions of the Kerguelen lavas are variable and have been used to infer that the mantle sources of these lavas reflect contributions from the depleted upper mantle, a common plume component, and the EM1 mantle component (perhaps recycled lower continental crust; e.g. Frey et al., 2002). The ƒO2 of the lavas of the Kerguelen LIP may thus reflect mixing of the upper mantle (i.e., near QFM), the plume component, and continental crust. We present new μ-XANES measurements of Fe3+/ΣFe ratios in a suite of 21 submarine glasses from Kerguelen. Over a narrow range in MgO (6.5-7.5 wt%), these glasses have Fe3+/ΣFe ratios of 0.16-0.18, corresponding to an ƒO2 of QFM+0.23 to +0.38 (at 1 atm, 1200°C). The H2O/Ce and Cl/K ratios of these glasses suggest that they did not assimilate significant amounts of altered oceanic crust. Also, S-FeOT variations indicate that the magmas are near sulfide saturation. These lavas were erupted in 1000 m of water, precluding significant loss of S to a vapor phase. At a given MgO content, samples from Kerguelen have similar to higher Fe3+/ΣFe ratios than the average values found in samples from along the Indian mid-ocean ridge, which could indicate a more oxidized mantle source. In addition, increases in Fe3+/ΣFe ratios of the Kerguelen samples, over a narrow

  14. Ultrathin reduced graphene oxide films as transparent top-contacts for light switchable solid-state molecular junctions

    DEFF Research Database (Denmark)

    Li, Tao; Jevric, Martyn; Hauptmann, Jonas Rahlf

    2013-01-01

    A new type of solid-state molecular junction is introduced, which employs reduced graphene oxide as a transparent top contact that permits a self-assembled molecular monolayer to be photoswitched in situ, while simultaneously enabling charge-transport measurements across the molecules. The electr......A new type of solid-state molecular junction is introduced, which employs reduced graphene oxide as a transparent top contact that permits a self-assembled molecular monolayer to be photoswitched in situ, while simultaneously enabling charge-transport measurements across the molecules...

  15. Reactivity of biogenic manganese oxide for metal sequestration and photochemistry: Computational solid state physics study

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, K.D.; Sposito, G.

    2010-02-01

    Many microbes, including both bacteria and fungi, produce manganese (Mn) oxides by oxidizing soluble Mn(II) to form insoluble Mn(IV) oxide minerals, a kinetically much faster process than abiotic oxidation. These biogenic Mn oxides drive the Mn cycle, coupling it with diverse biogeochemical cycles and determining the bioavailability of environmental contaminants, mainly through strong adsorption and redox reactions. This mini review introduces recent findings based on quantum mechanical density functional theory that reveal the detailed mechanisms of toxic metal adsorption at Mn oxide surfaces and the remarkable role of Mn vacancies in the photochemistry of these minerals.

  16. Solid state oxidation of phenols to quinones with sodium perborate on wet montmorillonite K10

    Energy Technology Data Exchange (ETDEWEB)

    Hashemi, Mohammed M.; Eftekhari-Sis, Bagher; Khalili, Behzad; Karimi-Jaberi, Zahed [Sharif University of Technology, Tehran (Iran, Islamic Republic of). Dept. of Chemistry]. E-mail: mhashemi@sharif.edu

    2005-09-15

    Phenols were oxidized to quinones using sodium perborate (SPB) on wet montmorillonite as oxidant. The reaction was carried out at ambient temperature on the solid phase under solvent free conditions. (author)

  17. Solid state oxidation of phenols to quinones with sodium perborate on wet montmorillonite K10

    International Nuclear Information System (INIS)

    Hashemi, Mohammed M.; Eftekhari-Sis, Bagher; Khalili, Behzad; Karimi-Jaberi, Zahed

    2005-01-01

    Phenols were oxidized to quinones using sodium perborate (SPB) on wet montmorillonite as oxidant. The reaction was carried out at ambient temperature on the solid phase under solvent free conditions. (author)

  18. Oxidation of an aluminium-magnesium alloy in liquid state. Methodology of determination of mechanisms from not necessarily repeatable experiments

    International Nuclear Information System (INIS)

    Surla, Karine

    1998-01-01

    This research thesis reports the study of the oxidation of an aluminium-5 pc magnesium alloy in its liquid state in an oxygen environment, using thermogravimetric analysis and that of magnesium in its solid state. In a first part, the author reports a thermodynamic and bibliographical study on magnesium transformation in its solid state (Mg/O 2 and Mg/H 2 O systems, transformation with dry and humid synthetic air, oxidation inhibitors) and on Al-Mg alloy transformation in presence of oxygen (thermodynamic properties of aluminium-rich Al-Mg alloys, Al-Mg/O 2 /N 2 and Al-Mg/O 2 /N 2 /H 2 O systems). The next parts address the selection of reaction systems for the different cases (oxidation of solid magnesium in oxygen, oxidation of the Al-Mg alloy in oxygen), the modelling of the formation of magnesia from solid magnesium and from the Al-Mg alloy, and the modelling of the liquid Al-Mg A5182 alloy oxidation in oxygen [fr

  19. Hydrophobic matrix-free graphene-oxide composites with isotropic and nematic states

    Science.gov (United States)

    Wåhlander, Martin; Nilsson, Fritjof; Carlmark, Anna; Gedde, Ulf W.; Edmondson, Steve; Malmström, Eva

    2016-08-01

    We demonstrate a novel route to synthesise hydrophobic matrix-free composites of polymer-grafted graphene oxide (GO) showing isotropic or nematic alignment and shape-memory effects. For the first time, a cationic macroinitiator (MI) has been immobilised on anionic GO and subsequently grafted with hydrophobic polymer grafts. Dense grafts of PBA, PBMA and PMMA with a wide range of average graft lengths (MW: 1-440 kDa) were polymerised by surface-initiated controlled radical precipitation polymerisation from the statistical MI. The surface modification is designed similarly to bimodal graft systems, where the cationic MI generates nanoparticle repulsion, similar to dense short grafts, while the long grafts offer miscibility in non-polar environments and cohesion. The state-of-the-art dispersions of grafted GO were in the isotropic state. Transparent and translucent matrix-free GO-composites could be melt-processed directly using only grafted GO. After processing, birefringence due to nematic alignment of grafted GO was observed as a single giant Maltese cross, 3.4 cm across. Permeability models for composites containing aligned 2D-fillers were developed, which were compared with the experimental oxygen permeability data and found to be consistent with isotropic or nematic states. The storage modulus of the matrix-free GO-composites increased with GO content (50% increase at 0.67 wt%), while the significant increases in the thermal stability (up to 130 °C) and the glass transition temperature (up to 17 °C) were dependent on graft length. The tuneable matrix-free GO-composites with rapid thermo-responsive shape-memory effects are promising candidates for a vast range of applications, especially selective membranes and sensors.We demonstrate a novel route to synthesise hydrophobic matrix-free composites of polymer-grafted graphene oxide (GO) showing isotropic or nematic alignment and shape-memory effects. For the first time, a cationic macroinitiator (MI) has been

  20. The Effect of Precursor Ligands and Oxidation State in the Synthesis of Bimetallic Nano-Alloys

    KAUST Repository

    LaGrow, Alec P.

    2015-05-12

    The characteristics of bimetallic nanomaterials are dictated by their size, shape and elemental distribution. Solution synthesis is widely utilized to form nanomaterials, such as nanoparticles, with controlled size and shape. However, the effects of variables on the characteristics of bimetallic nanomaterials are not completely understood. In this study, we used a continuous-flow synthetic strategy to explore the effects of the ligands and the oxidation state of a metal precursor in a shape-controlled synthesis on the final shape of the nanomaterials and the elemental distribution within the alloy. We demonstrate that this strategy can tune the size of monodisperse PtM (M=Ni or Cu) alloy nanocrystals ranging from 3 to 16 nm with an octahedral shape using acetylacetonate or halide precursors of Pt(II), Pt(IV) and Ni or Cu (II). The nanoparticles formed from halide precursors showed an enrichment of platinum on their surfaces, and the bromides could oxidatively etch the nanoparticles during synthesis with the O2/Br- pair. The two nanocrystal precursors can be uti-lized independently and can control the size with a trend of Pt(acac)2

  1. Electrochemical and spectroscopic studies of some less stable oxidation states of selected lanthanide and actinide elements

    International Nuclear Information System (INIS)

    Hobart, D.E.

    1981-06-01

    Simultaneous observation of electrochemical and spectroscopic properties (spectroelectrochemistry) at optically transparent electrodes (OTE's) was used to study some less stable oxidation states of selected lanthanide and actinide elements. Cyclic voltammetry at microelectrodes was used in conjunction with spectroelectrochemistry for the study of redox couples. Additional analytical techniques were used. The formal reduction potential (E 0 ') values of the M(III)/M(II) redox couples in 1 M KCl at pH 6 were -0.34 +- 0.01 V for Eu, -1.18 +- 0.01 V for Yb, and -1.50 +- 0.01 V for Sm. Spectropotentiostatic determination of E 0 ' for the Eu(III)/Eu(II) redox couple yielded a value of -0.391 +- 0.005 V. Spectropotentiostatic measurement of the Ce(IV)/Ce(III) redox couple in concentrated carbonate solution gave E 0 ' equal to 0.051 +- 0.005 V, which is about 1.7 V less positive than the E 0 ' value in noncomplexing solution. This same difference in potential was observed for the E 0 ' values of the Pr(IV)/Pr(III) and Tb(IV)/Tb(III) redox couples in carbonate solution, and thus Pr(IV) and Tb(IV) were stabilized in this medium. The U(VI)/U(V)/U(IV) and U(IV)/U(III) redox couples were studied in 1 M KCl at OTE's. Spectropotentiostatic measurement of the Np(VI)/Np(V) redox couple in 1 M HClO 4 gave an E 0 ' value of 1.140 +- 0.005 V. An E 0 ' value of 0.46 +- 0.01 V for the Np(VII)/Np(VI) couple was found by voltammetry. Oxidation of Am(III) was studied in concentrated carbonate solution, and a reversible cyclic voltammogram for the Am(IV)/Am(III) couple yielded E 0 ' = 0.92 +- 0.01 V in this medium; this value was used to estimate the standard reduction potential (E 0 ) of the couple as 2.62 +- 0.01 V. Attempts to oxidize Cm(III) in concentrated carbonate solution were not successful which suggests that the predicted E 0 value for the Cm(IV)/Cm(III) redox couple may be in error

  2. The effect on phase separation of the oxidation state of molybdenum in a Na2O-B2O3-SiO2 glass

    International Nuclear Information System (INIS)

    Kawamoto, Y.; Clemens, K.; Tomozawa, M.; Warden, J.T.

    1981-01-01

    The effect of oxidation state on phase separation was studied for 13Na 2 O, 49B 2 O 3 , 38SiO 2 (mol%) glasses containing 1 mol% Mo oxide. The glasses were melted under various conditions to vary the oxidation states of Mo ions. The oxidation states of Mo ions were determined by chemical analysis and ESR. The crystallisation tendency, the immiscibility temperature, and the phase separation morphology of the glasses were examined by DTA, x-ray diffraction, opalescence method, and replica electron microscopy. Glasses containing Mo 4+ ions have a great tendency to precipitate MoO 2 crystals. The immiscibility temperature of glass goes through a minimum when the oxidation states of Mo ions are changed. It was suggested that there is an optimum oxidation state to prevent crystallisation and to suppress the phase separation tendency of this system. (author)

  3. Operando XAS Study of the Surface Oxidation State on a Monolayer IrOx on RuOx and Ru Oxide Based Nanoparticles for Oxygen Evolution in Acidic Media

    DEFF Research Database (Denmark)

    Pedersen, Anders Filsøe; Escribano, Maria Escudero; Sebok, Bela

    2018-01-01

    that the average Ir oxidation state change is strongly affected by the coverage of atomic O. The observed shifts in oxidation state suggest that the surface has a high coverage of O at potentials just below the potential where oxygen evolution is exergonic in free energy. This observation is consistent...

  4. Effect of high doses of L-ascorbic acid on the antioxidative/oxidative state in the rats

    DEFF Research Database (Denmark)

    Niemiec, T.; Sawosz, E.; Chwalibog, André

    2005-01-01

    The objective of this study was to determine the effects of mega-doses of vitamin C (0.3, 0.6 and 0.9% of diet) as a dietary supplement for rats on selected indices of the antioxidative/oxidative state in 40 growing Wistar rats (4x10). It was found that L-ascorbic acid and Total Antioxidative State...... (TAS) in plasma did not increase with increasing vitamin C supply. The results indicate that high doses of L-ascorbic acid (0.3 and 0.9 but not 0.6%) increased the concentration of this antioxidant in plasma. Supplementation of vitamin C above 0.3% to the diets had pro-oxidative effects on lipid...... structures, while application of 0.9% promoted oxidative degradation of rat livers....

  5. Short review of high-pressure crystal growth and magnetic and electrical properties of solid-state osmium oxides

    Energy Technology Data Exchange (ETDEWEB)

    Yamaura, Kazunari, E-mail: YAMAURA.Kazunari@nims.go.jp [Superconducting Properties Unit, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Graduate School of Chemical Sciences and Engineering, Hokkaido University, North 10 West 8, Kita-ku, Sapporo, Hokkaido 060-0810 (Japan)

    2016-04-15

    High-pressure crystal growth and synthesis of selected solid-state osmium oxides, many of which are perovskite-related types, are briefly reviewed, and their magnetic and electrical properties are introduced. Crystals of the osmium oxides, including NaOsO{sub 3}, LiOsO{sub 3}, and Na{sub 2}OsO{sub 4}, were successfully grown under high-pressure and high-temperature conditions at 6 GPa in the presence of an appropriate amount of flux in a belt-type apparatus. The unexpected discovery of a magnetic metal–insulator transition in NaOsO{sub 3}, a ferroelectric-like transition in LiOsO{sub 3}, and high-temperature ferrimagnetism driven by a local structural distortion in Ca{sub 2}FeOsO{sub 6} may represent unique features of the osmium oxides. The high-pressure and high-temperature synthesis and crystal growth has played a central role in the development of solid-state osmium oxides and the elucidation of their magnetic and electronic properties toward possible use in multifunctional devices. - Graphical Abstract: Flux-grown crystals of NaOsO{sub 3} under high-pressure and high-temperature conditions in a belt-type apparatus. The crystal shows a magnetically driven metal–insulator transition at a temperature of 410 K. - Highlights: • Short review of high-pressure crystal growth of solid-state osmium oxides. • Wide variety of magnetic properties of solid-state osmium oxides. • Perovskite and related dense structures stabilized at 3–17 GPa.

  6. Pu oxidation state distributions in suspensions of the Mont Terri Opalinus Clay isolate Sporomusa sp. MT-2.99

    Energy Technology Data Exchange (ETDEWEB)

    Moll, Henry [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Biogeochemistry; Cherkouk, Andrea [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). HZDR Young Investigator Group; Bok, Frank [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Surface Processes

    2017-06-01

    The time-dependent {sup 242}Pu oxidation state distribution in the presence of Sporomusa sp. cells as a function of pH with or without Na-pyruvate was analyzed. In all cases, the presence of bacterial cells enhanced removal of Pu from solution and accelerated Pu interaction reactions, e.g. biosorption and bioreduction.

  7. Pu oxidation state distributions in suspensions of the Mont Terri Opalinus Clay isolate Sporomusa sp. MT-2.99

    International Nuclear Information System (INIS)

    Moll, Henry; Cherkouk, Andrea; Bok, Frank

    2017-01-01

    The time-dependent "2"4"2Pu oxidation state distribution in the presence of Sporomusa sp. cells as a function of pH with or without Na-pyruvate was analyzed. In all cases, the presence of bacterial cells enhanced removal of Pu from solution and accelerated Pu interaction reactions, e.g. biosorption and bioreduction.

  8. Arsenic K-edge X-ray absorption near-edge spectroscopy to determine oxidation states of arsenic of a coastal aquifer–aquitard system

    International Nuclear Information System (INIS)

    Wang, Ya; Jiao, Jiu Jimmy; Zhu, Sanyuan; Li, Yiliang

    2013-01-01

    Determination of oxidation states of solid-phase arsenic in bulk sediments is a valuable step in the evaluation of its bioavailability and environmental fate in deposits, but is difficult when the sediments have low arsenic contents and heterogeneous distribution of arsenic species. As K-edge X-ray absorption near-edge spectroscopy (XANES) was used to determine quantitatively the oxidation states of arsenic in sediments collected from different depths of boreholes in the Pearl River Delta, China, where the highest aquatic arsenic concentration is 161.4 μg/L, but the highest solid arsenic content only 39.6 mg/kg. The results demonstrated that XANES is efficient in determining arsenic oxidation states of the sediments with low arsenic contents and multiple arsenic species. The study on the high-resolution vertical variations of arsenic oxidation states also indicated that these states are influenced strongly by groundwater activities. With the help of geochemical data, solid arsenic speciation, toxicity and availability were further discussed. -- Highlights: •XANES is efficient in determining arsenic oxidation states of the bulk sediments. •Distribution of arsenic oxidation states is consistent with geochemical conditions. •Arsenic oxidation states are influenced strongly by groundwater activities. -- As K-edge X-ray absorption near-edge spectroscopy is efficient in determining arsenic oxidation states of the bulk sediments with low arsenic contents and heterogeneous distribution of arsenic species

  9. Visualizing chemical states and defects induced magnetism of graphene oxide by spatially-resolved-X-ray microscopy and spectroscopy.

    Science.gov (United States)

    Wang, Y F; Singh, Shashi B; Limaye, Mukta V; Shao, Y C; Hsieh, S H; Chen, L Y; Hsueh, H C; Wang, H T; Chiou, J W; Yeh, Y C; Chen, C W; Chen, C H; Ray, Sekhar C; Wang, J; Pong, W F; Takagi, Y; Ohigashi, T; Yokoyama, T; Kosugi, N

    2015-10-20

    This investigation studies the various magnetic behaviors of graphene oxide (GO) and reduced graphene oxides (rGOs) and elucidates the relationship between the chemical states that involve defects therein and their magnetic behaviors in GO sheets. Magnetic hysteresis loop reveals that the GO is ferromagnetic whereas photo-thermal moderately reduced graphene oxide (M-rGO) and heavily reduced graphene oxide (H-rGO) gradually become paramagnetic behavior at room temperature. Scanning transmission X-ray microscopy and corresponding X-ray absorption near-edge structure spectroscopy were utilized to investigate thoroughly the variation of the C 2p(π*) states that are bound with oxygen-containing and hydroxyl groups, as well as the C 2p(σ*)-derived states in flat and wrinkle regions to clarify the relationship between the spatially-resolved chemical states and the magnetism of GO, M-rGO and H-rGO. The results of X-ray magnetic circular dichroism further support the finding that C 2p(σ*)-derived states are the main origin of the magnetism of GO. Based on experimental results and first-principles calculations, the variation in magnetic behavior from GO to M-rGO and to H-rGO is interpreted, and the origin of ferromagnetism is identified as the C 2p(σ*)-derived states that involve defects/vacancies rather than the C 2p(π*) states that are bound with oxygen-containing and hydroxyl groups on GO sheets.

  10. Oxidative Stress State Is Associated with Left Ventricular Mechanics Changes, Measured by Speckle Tracking in Essential Hypertensive Patients

    Directory of Open Access Journals (Sweden)

    Luis Antonio Moreno-Ruíz

    2015-01-01

    Full Text Available The oxidative stress state is characterized by an increase in oxygen reactive species that overwhelms the antioxidant defense; we do not know if these pathological changes are correlated with alterations in left ventricular mechanics. The aim was correlating the oxidative stress state with the left ventricular global longitudinal strain (GLS and the left ventricular end diastolic pressure (LVEDP. Twenty-five patients with essential hypertension and 25 controls paired by age and gender were studied. All of the participants were subjected to echocardiography and biochemical determination of oxidative stress markers. The hypertensive patients, compared with control subjects, had significantly (p<0.05 higher levels of oxidized proteins (5.03±1.05 versus 4.06±0.63 nmol/mg, lower levels of extracellular superoxide dismutase (EC-SOD activity (0.045±0.02 versus 0.082±0.02 U/mg, higher LVEDP (16.2±4.5 versus 11.3±1.6 mm Hg, and lower GLS (−12% versus −16%. Both groups had preserved ejection fraction and the results showed a positive correlation of oxidized proteins with GLS (r=0.386, p=0.006 and LVEDP (r=0.389, p=0.005; we also found a negative correlation of EC-SOD activity with GLS (r=-0.404, p=0.004 and LVEDP (r=-0.347, p=0.014.

  11. System Tb-Fe-O: thermodynamic properties of ternary oxides using solid-state electrochemical cells

    International Nuclear Information System (INIS)

    Rakshit, S.K.; Parida, S.C.; Dash, S.; Singh, Ziley; Prasad, R.; Venugopal, V.

    2003-01-01

    The standard molar Gibbs free energies of formation of TbFeO 3 (s) and Tb 3 Fe 5 O 12 (s) have been determined using solid-state electrochemical cell employing different solid electrolytes. The reversible emfs of the following solid-state electrochemical cells have been measured in the temperature range 1050≤T/K≤1250. Cell (I):(-)Pt/{TbFeO 3 (s)+Tb 2 O 3 (s)+Fe(s)}//YDT/CSZ//{Fe(s)+Fe 0.95 O(s)}/Pt(+))) (Cell (II):(-)Pt/{Fe(s)+Fe 0.95 O(s)}//CSZ//{TbFeO 3 (s)+Tb 3 Fe 5 O 12 (s)+Fe 3 O 4 (s)}/Pt(+) The oxygen chemical potentials corresponding to the three-phase equilibria involving the ternary oxides have been computed from the emf data. The standard molar Gibbs free energies of formation of solid TbFeO 3 and Tb 3 Fe 5 O 12 calculated by the least-squares regression analysis of the data obtained in the present study are given by {Δ f G compfn m (TbFeO 3 ,s)/(kJ·mol -1 )±3.2}=-1357.5+0.2531·(T/K); (1050≤T/K≤1548);))and({Δ f G compfn m (Tb 3 Fe 5 O 12 ,s)/(kJ·mol -1 )±3.5}=-4901.7+ 0.9997·(T/K); (1050≤T/K≤1250).)) The uncertainty estimates for Δ f G compfn m include the standard deviation in the emf and uncertainty in the data taken from the literature. Based on the thermodynamic information, oxygen potential diagram and chemical potential diagrams were computed for the system Tb-Fe-O at T=1250 K

  12. Studi On Oxidation State Of U In Ba2NdUO6

    International Nuclear Information System (INIS)

    Firman Windarto, Hendri

    1996-01-01

    Ba 2 NdUO 6 is not of the important compounds that is formed from a solidification process for high level liquid waste using super high temperature method Ba 2 NdUO 6 has ordered perovskite structure. The objective of this study is to investigate oxidation state of U in Ba 2 NdUO 6 . The properties of Ba 2 NdUO 6 were observed by using Faraday-type torsion magnetometer and X-ray Photoelectron Spectrometer (XPS). The magnetic susceptibility measured in the temperature range of 4K to room temperature showed that the Ba 2 NdUO 6 is paramagnetism that obeys the Curie-Weiss law. The effective moment of Ba 2 NdUO 6 is 3.04 μB. The results of xPs spectrum showed that the peaks of U4f for Ba 2 NdUO 6 appeared exactly between binding energy of UO 2 and UO 3 . It can be concluded that Ba 2 NdUO 6 has binding energy peaks corresponding to pentavalent uranium

  13. Petrology of chromite in ureilites: Deconvolution of primary oxidation states and secondary reduction processes

    Science.gov (United States)

    Goodrich, Cyrena Anne; Harlow, George E.; Van Orman, James A.; Sutton, Stephen R.; Jercinovic, Michael J.; Mikouchi, Takashi

    2014-06-01

    Ureilites are ultramafic achondrites thought to be residues of partial melting on a carbon-rich asteroid. They show a trend of FeO-variation (olivine Fo from ∼74 to 95) that suggests variation in oxidation state. Whether this variation was established during high-temperature igneous processing on the ureilite parent body (UPB), or preserved from nebular precursors, is a subject of debate. The behavior of chromium in ureilites offers a way to assess redox conditions during their formation and address this issue, independent of Fo. We conducted a petrographic and mineral compositional study of occurrences of chromite (Cr-rich spinel) in ureilites, aimed at determining the origin of the chromite in each occurrence and using primary occurrences to constrain models of ureilite petrogenesis. Chromite was studied in LEW 88774 (Fo 74.2), NWA 766 (Fo 76.7), NWA 3109 (Fo 76.3), HaH 064 (Fo 77.5), LAP 03587 (Fo 74.9), CMS 04048 (Fo 76.4), LAP 02382 (Fo 78.6) and EET 96328 (Fo 85.2). Chromite occurs in LEW 88774 (∼5 vol.%), NWA 766 (event involved initial elevation of T (to 1300-1400 °C), followed by rapid decompression and drop in T (to exclusively in low-Fo samples supports the interpretation that the ureilite FeO-variation was established during igneous processing on the UPB.

  14. Waste management state-of-the-art review for mixed-oxide fuel fabrication facilities

    International Nuclear Information System (INIS)

    Woodsum, H.C.; Goodman, J.

    1977-11-01

    This report provides a state-of-the-art review of the waste management for mixed-oxide (MOX) fuel fabrication facilities. The intent of this report is to focus on those processes and regulatory issues which have a direct bearing on existing and anticipated future management of transuranic (TRU) wastes from a commercial MOX fuel fabrication faciity. Recent government agency actions are reviewed with regard to their impact on existing and projected waste management regulations; and it is concluded that acceleration in the development of regulations, standards, and criteria is one of the most important factors in the implementation of improved MOX plant waste management techniques. ERDA development programs pertaining to the management of TRU wastes have been reviewed and many promising methods for volume reduction of both solid and liquid wastes are discussed. For solid wastes, these methods include compaction, shredding and baling, combustion, acid digestion, and decontamination by electropolishing or by electrolytic treatment. For liquid wastes, treatment options include evaporation, drying, calcination, flocculation, ion exchange, filtration, reverse osmosis, combustion (of combustible organics), and bioprocessing. Based on this review, it is recommended that ERDA continue with its combustible solid waste volume reduction program and complete these development activities by 1979. Following this, a critical evaluation of solid waste volume reduction techniques should be made to select the most promising systems for a commercial MOX fuel facility

  15. Oxidation state of uranium in metamict and annealed zircon: near-infrared spectroscopic quantitative analysis

    CERN Document Server

    Zhang Ming; Ewing, R C

    2003-01-01

    Radiation and thermally induced changes in the oxidation state of uranium in metamict zircon have been systematically analysed, for the first time, using polarized near-infrared spectroscopy. The results showed that in damaged zircon U ions in crystalline domains exhibited relatively sharp, anisotropic signals from tetravalent and pentavalent U ions in crystalline domains (U sub c sub r sub y sub s sub t sub a sub l sup 4 sup + and U sub c sub r sub y sub s sub t sub a sub l sup 5 sup +). The linewidths and peak positions of the 4834 cm sup - sup 1 band (U sub c sub r sub y sub s sub t sub a sub l sup 4 sup + , E || c) and the 6668 cm sup - sup 1 band (U sub c sub r sub y sub s sub t sub a sub l sup 5 sup + , E perp. c) are a non-linear function of the self-radiation dose. They reach nearly constant values at doses greater than approx 3.5 x 10 sup 1 sup 8 alpha-events g sup - sup 1. Quantitative analysis of U sub c sub r sub y sub s sub t sub a sub l sup 4 sup + and U sub c sub r sub y sub s sub t sub a sub l...

  16. Atomic scale imaging of competing polar states in a Ruddlesden–Popper layered oxide

    Science.gov (United States)

    Stone, Greg; Ophus, Colin; Birol, Turan; Ciston, Jim; Lee, Che-Hui; Wang, Ke; Fennie, Craig J.; Schlom, Darrell G.; Alem, Nasim; Gopalan, Venkatraman

    2016-01-01

    Layered complex oxides offer an unusually rich materials platform for emergent phenomena through many built-in design knobs such as varied topologies, chemical ordering schemes and geometric tuning of the structure. A multitude of polar phases are predicted to compete in Ruddlesden–Popper (RP), An+1BnO3n+1, thin films by tuning layer dimension (n) and strain; however, direct atomic-scale evidence for such competing states is currently absent. Using aberration-corrected scanning transmission electron microscopy with sub-Ångstrom resolution in Srn+1TinO3n+1 thin films, we demonstrate the coexistence of antiferroelectric, ferroelectric and new ordered and low-symmetry phases. We also directly image the atomic rumpling of the rock salt layer, a critical feature in RP structures that is responsible for the competing phases; exceptional quantitative agreement between electron microscopy and density functional theory is demonstrated. The study shows that layered topologies can enable multifunctionality through highly competitive phases exhibiting diverse phenomena in a single structure. PMID:27578622

  17. Atomic scale imaging of competing polar states in a Ruddlesden-Popper layered oxide.

    Science.gov (United States)

    Stone, Greg; Ophus, Colin; Birol, Turan; Ciston, Jim; Lee, Che-Hui; Wang, Ke; Fennie, Craig J; Schlom, Darrell G; Alem, Nasim; Gopalan, Venkatraman

    2016-08-31

    Layered complex oxides offer an unusually rich materials platform for emergent phenomena through many built-in design knobs such as varied topologies, chemical ordering schemes and geometric tuning of the structure. A multitude of polar phases are predicted to compete in Ruddlesden-Popper (RP), An+1BnO3n+1, thin films by tuning layer dimension (n) and strain; however, direct atomic-scale evidence for such competing states is currently absent. Using aberration-corrected scanning transmission electron microscopy with sub-Ångstrom resolution in Srn+1TinO3n+1 thin films, we demonstrate the coexistence of antiferroelectric, ferroelectric and new ordered and low-symmetry phases. We also directly image the atomic rumpling of the rock salt layer, a critical feature in RP structures that is responsible for the competing phases; exceptional quantitative agreement between electron microscopy and density functional theory is demonstrated. The study shows that layered topologies can enable multifunctionality through highly competitive phases exhibiting diverse phenomena in a single structure.

  18. Carbonate-linked poly(ethylene oxide) polymer electrolytes towards high performance solid state lithium batteries

    International Nuclear Information System (INIS)

    He, Weisheng; Cui, Zili; Liu, Xiaochen; Cui, Yanyan; Chai, Jingchao; Zhou, Xinhong; Liu, Zhihong; Cui, Guanglei

    2017-01-01

    The classic poly(ethylene oxide) (PEO) based solid polymer electrolyte suffers from poor ionic conductivity of ambient temperature, low lithium ion transference number and relatively narrow electrochemical window (<4.0 V vs. Li + /Li). Herein, the carbonate-linked PEO solid polymer such as poly(diethylene glycol carbonate) (PDEC) and poly(triethylene glycol carbonate) (PTEC) were explored to find out the feasibility of resolving above issues. It was proven that the optimized ionic conductivity of PTEC based electrolyte reached up to 1.12 × 10 −5 S cm −1 at 25 °C with a decent lithium ion transference number of 0.39 and a wide electrochemical window about 4.5 V vs. Li + /Li. In addition, the PTEC based Li/LiFePO 4 cell could be reversibly charged and discharged at 0.05 C-rates at ambient temperature. Moreover, the higher voltage Li/LiFe 0.2 Mn 0.8 PO 4 cell (cutoff voltage 4.35 V) possessed considerable rate capability and excellent cycling performance even at ambient temperature. Therefore, these carbonate-linked PEO electrolytes were demonstrated to be fascinating candidates for the next generation solid state lithium batteries simultaneously with high energy and high safety.

  19. 3 and 4 oxidation state element solubilities in borosilicate glasses. Implement to actinides in nuclear glasses

    International Nuclear Information System (INIS)

    Cachia, J.N.

    2005-12-01

    In order to ensure optimal radionuclides containment, the knowledge of the actinide loading limits in nuclear waste glasses and also the comprehension of the solubilization mechanisms of these elements are essential. A first part of this manuscript deals with the study of the differences in solubility of the tri and tetravalent elements (actinides and surrogates) particularly in function of the melting temperature. The results obtained indicate that trivalent elements (La, Gd, Nd, Am, Cm) exhibit a higher solubility than tetravalent elements (Hf, Th, Pu). Consequently, it was planned to reduce plutonium at the oxidation state (III), the later being essentially tetravalent in borosilicate glasses. An innovating reduction process of multi-valent elements (cerium, plutonium) using silicon nitride has been developed in a second part of this work. Reduced plutonium-bearing glasses synthesized by Si 3 N 4 addition made it possible to double the plutonium solubility from 2 to 4 wt% at 1200 deg C. A structural approach to investigate the differences between tri and tetravalent elements was finally undertaken. These investigations were carried out by X-rays Absorption Spectroscopy (EXAFS) and NMR. Trivalent rare earth and actinide elements seem to behave as network modifiers while tetravalent elements rather present true intermediaries' behaviour. (author)

  20. Exploratory Characterization of Phenolic Compounds with Demonstrated Anti-Diabetic Activity in Guava Leaves at Different Oxidation States

    Directory of Open Access Journals (Sweden)

    Elixabet Díaz-de-Cerio

    2016-05-01

    Full Text Available Psidium guajava L. is widely used like food and in folk medicine all around the world. Many studies have demonstrated that guava leaves have anti-hyperglycemic and anti-hyperlipidemic activities, among others, and that these activities belong mainly to phenolic compounds, although it is known that phenolic composition in guava tree varies throughout seasonal changes. Andalusia is one of the regions in Europe where guava is grown, thus, the aim of this work was to study the phenolic compounds present in Andalusian guava leaves at different oxidation states (low, medium, and high. The phenolic compounds in guava leaves were determined by HPLC-DAD-ESI-QTOF-MS. The results obtained by chromatographic analysis reported that guava leaves with low degree of oxidation had a higher content of flavonols, gallic, and ellagic derivatives compared to the other two guava leaf samples. Contrary, high oxidation state guava leaves reported the highest content of cyanidin-glucoside that was 2.6 and 15 times higher than guava leaves with medium and low oxidation state, respectively. The QTOF platform permitted the determination of several phenolic compounds with anti-diabetic properties and provided new information about guava leaf phenolic composition that could be useful for nutraceutical production.

  1. Exploratory Characterization of Phenolic Compounds with Demonstrated Anti-Diabetic Activity in Guava Leaves at Different Oxidation States.

    Science.gov (United States)

    Díaz-de-Cerio, Elixabet; Verardo, Vito; Gómez-Caravaca, Ana María; Fernández-Gutiérrez, Alberto; Segura-Carretero, Antonio

    2016-05-11

    Psidium guajava L. is widely used like food and in folk medicine all around the world. Many studies have demonstrated that guava leaves have anti-hyperglycemic and anti-hyperlipidemic activities, among others, and that these activities belong mainly to phenolic compounds, although it is known that phenolic composition in guava tree varies throughout seasonal changes. Andalusia is one of the regions in Europe where guava is grown, thus, the aim of this work was to study the phenolic compounds present in Andalusian guava leaves at different oxidation states (low, medium, and high). The phenolic compounds in guava leaves were determined by HPLC-DAD-ESI-QTOF-MS. The results obtained by chromatographic analysis reported that guava leaves with low degree of oxidation had a higher content of flavonols, gallic, and ellagic derivatives compared to the other two guava leaf samples. Contrary, high oxidation state guava leaves reported the highest content of cyanidin-glucoside that was 2.6 and 15 times higher than guava leaves with medium and low oxidation state, respectively. The QTOF platform permitted the determination of several phenolic compounds with anti-diabetic properties and provided new information about guava leaf phenolic composition that could be useful for nutraceutical production.

  2. Exploratory Characterization of Phenolic Compounds with Demonstrated Anti-Diabetic Activity in Guava Leaves at Different Oxidation States

    Science.gov (United States)

    Díaz-de-Cerio, Elixabet; Verardo, Vito; Gómez-Caravaca, Ana María; Fernández-Gutiérrez, Alberto; Segura-Carretero, Antonio

    2016-01-01

    Psidium guajava L. is widely used like food and in folk medicine all around the world. Many studies have demonstrated that guava leaves have anti-hyperglycemic and anti-hyperlipidemic activities, among others, and that these activities belong mainly to phenolic compounds, although it is known that phenolic composition in guava tree varies throughout seasonal changes. Andalusia is one of the regions in Europe where guava is grown, thus, the aim of this work was to study the phenolic compounds present in Andalusian guava leaves at different oxidation states (low, medium, and high). The phenolic compounds in guava leaves were determined by HPLC-DAD-ESI-QTOF-MS. The results obtained by chromatographic analysis reported that guava leaves with low degree of oxidation had a higher content of flavonols, gallic, and ellagic derivatives compared to the other two guava leaf samples. Contrary, high oxidation state guava leaves reported the highest content of cyanidin-glucoside that was 2.6 and 15 times higher than guava leaves with medium and low oxidation state, respectively. The QTOF platform permitted the determination of several phenolic compounds with anti-diabetic properties and provided new information about guava leaf phenolic composition that could be useful for nutraceutical production. PMID:27187352

  3. The protonation state around TyrD/TyrD• in photosystem II is reflected in its biphasic oxidation kinetics.

    Science.gov (United States)

    Sjöholm, Johannes; Ho, Felix; Ahmadova, Nigar; Brinkert, Katharina; Hammarström, Leif; Mamedov, Fikret; Styring, Stenbjörn

    2017-02-01

    The tyrosine residue D2-Tyr160 (Tyr D ) in photosystem II (PSII) can be oxidized through charge equilibrium with the oxygen evolving complex in PSII. The kinetics of the electron transfer from Tyr D has been followed using time-resolved EPR spectroscopy after triggering the oxidation of pre-reduced Tyr D by a short laser flash. After its oxidation Tyr D is observed as a neutral radical (Tyr D • ) indicating that the oxidation is coupled to a deprotonation event. The redox state of Tyr D was reported to be determined by the two water positions identified in the crystal structure of PSII [Saito et al. (2013) Proc. Natl. Acad. Sci. USA 110, 7690]. To assess the mechanism of the proton coupled electron transfer of Tyr D the oxidation kinetics has been followed in the presence of deuterated buffers, thereby resolving the kinetic isotope effect (KIE) of Tyr D oxidation at different H/D concentrations. Two kinetic phases of Tyr D oxidation - the fast phase (msec-sec time range) and the slow phase (tens of seconds time range) were resolved as was previously reported [Vass and Styring (1991) Biochemistry 30, 830]. In the presence of deuterated buffers the kinetics was significantly slower compared to normal buffers. Furthermore, although the kinetics were faster at both high pH and pD values the observed KIE was found to be similar (~2.4) over the whole pL range investigated. We assign the fast and slow oxidation phases to two populations of PSII centers with different water positions, proximal and distal respectively, and discuss possible deprotonation events in the vicinity of Tyr D . Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Rapid Synthesis of Lead Oxide Nanorods by One-step Solid-state Chemical Reaction at Room Temperature

    Institute of Scientific and Technical Information of China (English)

    CAO, Ya-Li(曹亚丽); JIA, Dian-Zeng(贾殿赠); LIU, Lang(刘浪); LUO, Jian-Min(骆建敏)

    2004-01-01

    A simple and facile method was reported to synthesize lead oxide nanorods. Nanorods of lead oxide were obtained directly from grinding solid metal salt and sodium hydroxide in agate mortar with the assistance of a suitable nonionic surfactant in only one step, which is different from the result of hydroxide in solution. The product has been characterized by XRD, TEM and SEM. The formation mechanism of rod-like morphology is discussed and the surfactant plays an important soft-template role in modifying the interface of solid-state reaction and according process of rod-formation.

  5. Investigation of electrochemical behaviour and structure of oxide films on Ni60Nb40 alloy in amorphous and crystalline states

    International Nuclear Information System (INIS)

    Tomashov, N.D.; Skvortsova, I.B.; Gorodetskij, A.E.; Bogomolov, D.B.

    1987-01-01

    Electrochemical properties of Ni 60 Nb 40 alloy in amorphous and crystalline states as well as structure of oxide films forming during anode polarization in electrolytes on the surface of this alloy in both its states are investigated. It is stated that increased passive ability of Ni 60 Nb 40 alloys in amorphous state and high efficiency of chlorine evolution (2 n NaCl+HCl up to pH=0) anode process in comparison with crystalline state are defined by increased homogeneity and uniformity of passive films forming on amorphous alloy and their increased electron conductivity, that is in direct dependence on different structure of passive films forming on alloys in amorphous and crystalline states

  6. Assigning Oxidation States to Organic Compounds via Predictions from X-Ray Photoelectron Spectroscopy: A Discussion of Approaches and Recommended Improvements

    Science.gov (United States)

    Gupta, Vipul; Ganegoda, Hasitha; Engelhard, Mark H.; Terry, Jeff; Linford, Matthew R.

    2014-01-01

    The traditional assignment of oxidation states to organic molecules is problematic. Accordingly, in 1999, Calzaferri proposed a simple and elegant solution that is based on the similar electronegativities of carbon and hydrogen: hydrogen would be assigned an oxidation state of zero when bonded to carbon. Here, we show that X-ray photoelectron…

  7. Sulfur diffusion in dacitic melt at various oxidation states: Implications for volcanic degassing

    Science.gov (United States)

    Lierenfeld, Matthias Bernhard; Zajacz, Zoltán; Bachmann, Olivier; Ulmer, Peter

    2018-04-01

    The diffusivity of S in a hydrous dacitic melt (4.5-6.0 wt.% H2O) has been investigated in the temperature (T) and pressure (P) range of 950 °C to 1100 °C and 200 to 250 MPa, respectively. Three series of experiments were conducted at relatively low oxygen fugacity (fO2) conditions [0.8 log units below fayalite-magnetite-quartz equilibrium (FMQ -0.8); referred to as "low fO2"] and high fO2 conditions (FMQ +2.5; referred to as "high fO2") to determine if the diffusivity of S is affected by its oxidation state and speciation. Sulfur concentration profiles were measured by electron microprobe and the diffusion coefficient (D) was calculated by fitting these profiles. Sulfur diffusion is approximately one order of magnitude faster when S is dominantly present as sulfide species (low fO2) in comparison to the sulfate dominated experiments (high fO2). The following Arrhenian equations were obtained for high and low fO2 conditions at 200 MPa: high fO2: D = 10-5.92±0.86 * exp ({-137.3±21.5 kJ/mol}/{RT}) low fO2: D = 10-5.18±1.39 * exp ({-125.7±34.4 kJ/mol}/{RT}) where D is the average diffusion coefficient in m2 s-1, R is the gas constant in 8.3144 J mol-1 K-1 and T is the temperature in K. Our results demonstrate for the first time in natural melts that S diffusion is strongly sensitive to fO2. Our S diffusivities under low fO2 conditions are only slightly slower of those found for H2O, suggesting that S can be rather efficiently purged from reduced dacitic melts during volcanic eruptions. However, for more oxidized systems (e.g. subduction zones), S diffusion will be much slower and will hinder equilibrium syn-eruptive degassing during rapid decompression. Therefore, we conclude that the "excess" measured during many explosive volcanic eruptions in arcs is dominantly derived from S-rich bubble accumulation in the eruptible portion of the magma reservoir.

  8. Triplet-State Dissolved Organic Matter Quantum Yields and Lifetimes from Direct Observation of Aromatic Amine Oxidation.

    Science.gov (United States)

    Schmitt, Markus; Erickson, Paul R; McNeill, Kristopher

    2017-11-21

    Excited triplet state chromophoric dissolved organic matter ( 3 CDOM*) is a short-lived mixture of excited-state species that plays important roles in aquatic photochemical processes. Unlike the study of the triplet states of well-defined molecules, which are amenable to transient absorbance spectroscopy, the study of 3 CDOM* is hampered by it being a complex mixture and its low average intersystem crossing quantum yield (Φ ISC ). This study is an alternative approach to investigating 3 CDOM* using transient absorption laser spectroscopy. The radical cation of N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD), formed through oxidation by 3 CDOM*, was directly observable by transient absorption spectroscopy and was used to probe basic photophysical properties of 3 CDOM*. Quenching and control experiments verified that TMPD •+ was formed from 3 CDOM* under anoxic conditions. Model triplet sensitizers with a wide range of excited triplet state reduction potentials and CDOM oxidized TMPD at near diffusion-controlled rates. This gives support to the idea that a large cross-section of 3 CDOM* moieties are able to oxidize TMPD and that the complex mixture of 3 CDOM* can be simplified to a single signal. Using the TMPD •+ transient, the natural triplet lifetime and Φ ISC for different DOM isolates and natural waters were quantified; values ranged from 12 to 26 μs and 4.1-7.8%, respectively.

  9. The Oxidation State of Fe in Glasses from the Galapagos Archipelago: Variable Oxygen Fugacity as a Function of Mantle Source

    Science.gov (United States)

    Peterson, M. E.; Kelley, K. A.; Cottrell, E.; Saal, A. E.; Kurz, M. D.

    2015-12-01

    The oxidation state of the mantle plays an intrinsic role in the magmatic evolution of the Earth. Here we present new μ-XANES measurements of Fe3+/ΣFe ratios (a proxy for ƒO2) in a suite of submarine glasses from the Galapagos Archipelago. Using previously presented major, trace, and volatile elements and isotopic data for 4 groups of glass that come from distinct mantle sources (depleted upper mantle, 2 recycled, and a primitive mantle source) we show that Fe3+/ΣFe ratios vary both with the influence of shallow level processes and with variations in mantle source. Fe3+/ΣFe ratios increase with differentiation (i.e. decreasing MgO), but show a large variation at a given MgO. Progressive degassing of sulfur accompanies decreasing Fe3+/ΣFe ratios, while assimilation of hydrothermally altered crust (as indicated by increasing Sr/Sr*) is shown to increase Fe3+/ΣFe ratios. After taking these processes into account, there is still variability in the Fe3+/ΣFe ratios of the isotopically distinct sample suites studied, yielding a magmatic ƒO2 that ranges from ΔQFM = +0.16 to +0.74 (error ITE = enriched Sr and Pb isotopes) shows evidence of mixing between oxidized and reduced sources (ITE oxidized end-member = 0.177). This suggests that mantle sources in the Galapagos that are thought to contain recycled components (i.e., WD and ITE groups) have distinct oxidation states. The high 3He/4He Fernandina samples (HHe group) are shown to be the most oxidized (ave. 0.175 ± 0.006). With C/3He ratios an order of magnitude greater than MORB this suggests that the primitive mantle is a more carbonated and oxidized source than the depleted upper mantle.

  10. Oxidation-state distribution of plutonium in surface and subsurface waters at Thule, northwest Greenland

    International Nuclear Information System (INIS)

    McMahon, C.A.; Leon Vintro, L.; Mitchell, P.I.; Dahlgaard, H.

    2000-01-01

    The speciation of plutonium in Arctic waters sampled on the northwest Greenland shelf in August 1997 is discussed in this paper. Specifically, we report the results of analyses carried out on seawater sampled (a) close to the Thule air base where, in 1968, a US military aircraft carrying four nuclear weapons crashed on sea ice, releasing kilogram quantities of plutonium to the snow pack and underlying seabed sediments, and (b) at a reference station (Upernavik) located ∼400 km to the south. The data show that most of the plutonium in the dissolved phase at Thule is in the form of Pu(V, VI) (mean: 68±6%; n=6), with little if any distinction apparent between surface and bottom waters. Further, the oxidation state distribution at stations close to the accident site is similar to that measured at Upernavik, remote from this site. It is also similar to the distribution observed in shelf waters at mid-latitudes, suggesting that the underlying processes controlling plutonium speciation are insensitive to temperature over the range 0-25 deg. C. Measurements using tangential-flow ultrafiltration indicate that virtually all of the plutonium (including the fraction in a reduced chemical form) is present as fully dissolved species. Most of this plutonium would seem to be of weapons fallout origin, as the mean 238 Pu/ 239,240 Pu activity ratio in the water column (dissolved phase) at Thule (0.06±0.02; n=10) is similar to the global fallout ratio at this latitude (∼0.04). Thus, there is little evidence of weapons-grade plutonium in the water column at Thule at the present time

  11. The changing face of lower tropospheric sulfur oxides in the United States

    Directory of Open Access Journals (Sweden)

    G. M. Hidy

    2016-12-01

    Full Text Available Abstract Sulfur oxides, sulfur dioxide and airborne sulfate, SOx, are short-lived species in the troposphere whose concentrations in air and precipitation have changed dramatically in association with fossil fuel combustion. The historic rise in concentration is coincident with the era of the so-called “Anthropocene.” Unlike concentrations of long-lived species such as carbon dioxide, atmospheric SOx in the United States (US peaked between 1970 and 2005 then declined. The rise and fall of SOx is traced by comparing national data on emission changes, ambient concentrations, and precipitation sulfate from prior to World War II to the present. Surface SOx concentrations and precipitation sulfate have decreased with emissions in most parts of the US after the late 1970s. Continued reduction toward a natural “background” condition has depended on aggressive management of anthropogenic emission sources. Annual average ambient concentrations of SO2 and SO4 have become more uniform across the US at levels of 1–3 ppbv and 0.3–3 µg/m3, respectively. Precipitation SO4 has a nominal concentration generally less than 0.5 mg/L. The effective lifetime of SOx in the troposphere is a few days. This duration limits the spatial extent of emission source influence of SOx to regional scales, wherein spatial gradients in species concentrations lead to variations in human exposure and impacts on vulnerable terrestrial and aquatic ecosystems. The effects of domestic emission reductions on SOx levels are moderated by intra- and intercontinental transport of SOx from Canada, Mexico, Asia and elsewhere. The trends in tropospheric SOx concentrations illustrate the results of more than a century of rising public awareness and action to progressively reduce a US environmental risk, accomplished with advances in energy production technology that have maintained economic well-being.

  12. Global analysis of genetic variation in human arsenic (+ 3 oxidation state) methyltransferase (AS3MT)

    International Nuclear Information System (INIS)

    Fujihara, Junko; Soejima, Mikiko; Yasuda, Toshihiro; Koda, Yoshiro; Agusa, Tetsuro; Kunito, Takashi; Tongu, Miki; Yamada, Takaya; Takeshita, Haruo

    2010-01-01

    Human arsenic (+ 3 oxidation state) methyltransferase (AS3MT) is known to catalyze the methylation of arsenite. The objective of this study was to investigate the diversity of the AS3MT gene at the global level. The distribution of 18 single nucleotide polymorphisms (SNPs) in AS3MT was performed in 827 individuals from 10 populations (Japanese, Korean, Chinese, Mongolian, Tibetans, Sri Lankan Tamils, Sri Lankan Sinhalese, Nepal Tamangs, Ovambo, and Ghanaian). In the African populations, the A allele in A6144T was not observed; the allele frequencies of C35587 were much lower than those in other populations; the allele frequencies of A37616 and C37950 were relatively higher than those in other populations. Among Asian populations, Mongolians showed a different genotype distribution pattern. A lower C3963 and T6144 frequencies were observed, and, in the C37616A and T37950C polymorphism, the Mongolian population showed higher A37616 and C37950 allele frequencies than other Asian populations, similarly to the African populations. A total of 66 haplotypes were observed in the Ovambo, 48, in the Ghanaian, 99, in the Japanese, 103, in the Korean, 103, in the South Chinese, 20, in the Sri Lankan Tamil, 12, in the Sri Lankan Sinhalese, 21, in the Nepal Tamang, 50, in the Tibetan, and 45, in the Mongolian populations. The D' values between the SNP pairs were extremely high in the Sri Lankan Sinhalese population. Relatively higher D' values were observed in Mongolian and Sri Lankan Tamil populations. Network analysis showed two clusters that may have different origins, African and Asians (Chinese and/or Japanese). The present study is the first to demonstrate the existence of genetic heterogeneity in a world wide distribution of 18 SNPs in AS3MT.

  13. Metabolomic profiles of arsenic (+3 oxidation state) methyltransferase knockout mice: Effect of sex and arsenic exposure

    Science.gov (United States)

    Huang, Madelyn C.; Douillet, Christelle; Su, Mingming; Zhou, Kejun; Wu, Tao; Chen, Wenlian; Galanko, Joseph A.; Drobná, Zuzana; Saunders, R. Jesse; Martin, Elizabeth; Fry, Rebecca C.; Jia, Wei; Stýblo, Miroslav

    2016-01-01

    Arsenic (+3 oxidation state) methyltransferase (As3mt) is the key enzyme in the pathway for methylation of inorganic arsenic (iAs). Altered As3mt expression and AS3MT polymorphism have been linked to changes in iAs metabolism and in susceptibility to iAs toxicity in laboratory models and in humans. As3mt-knockout mice have been used to study the association between iAs metabolism and adverse effects of iAs exposure. However, little is known about systemic changes in metabolism of these mice and how these changes lead to their increased susceptibility to iAs toxicity. Here, we compared plasma and urinary metabolomes of male and female wild-type (WT) and As3mt-KO (KO) C57BL6 mice and examined metabolomic shifts associated with iAs exposure in drinking water. Surprisingly, exposure to 1 ppm As elicited only small changes in the metabolite profiles of either WT or KO mice. In contrast, comparisons of KO mice with WT mice revealed significant differences in plasma and urinary metabolites associated with lipid (phosphatidylcholines, cytidine, acyl-carnitine), amino acid (hippuric acid, acetylglycine, urea), and carbohydrate (L-sorbose, galactonic acid, gluconic acid) metabolism. Notably, most of these differences were sex-specific. Sex-specific differences were also found between WT and KO mice in plasma triglyceride and lipoprotein cholesterol levels. Some of the differentially changed metabolites (phosphatidylcholines, carnosine, and sarcosine) are substrates or products of reactions catalyzed by other methyltransferases. These results suggest that As3mt KO alters major metabolic pathways in a sex-specific manner, independent of iAs treatment, and that As3mt may be involved in other cellular processes beyond iAs methylation. PMID:26883664

  14. Determination of Pu Oxidation states in the HCl Media Using with UV-Visible Absorption Spectroscopic Techniques

    International Nuclear Information System (INIS)

    Lee, Myung Ho; Suh, Mu Yeol; Park, Kyoung Kyun; Park, Yeong Jae; Kim, Won Ho

    2006-01-01

    The spectroscopic characteristics of Pu (III, IV, V, VI) in the HCl media were investigated by measuring Pu oxidation states using a UV-Vis-NIR spectrophotometer (400-1200 nm) after adjusting Pu oxidation states with oxidation/reduction reagents. Pu in stock solution was reduced to Pu(III) with NH 2 OH · HCl, and oxidized to Pu(IV) and Pu(VI) with NaNO 2 and HCIO 4 , respectively. Also, Pu(V) was adjusted in the Pu(VI) solution with NH 2 OH · HCl. The major absorption peaks of Pu (IV) and Pu(III) were measured in the 470 nm and 600 nm, respectively. The major absorption peaks of Pu (VI) and Pu(V) were measured in the 830 nm and 1135 nm, respectively. There was not found to be significant changes of UV-V is absorption spectra for Pu(III), Pu(IV) and Pu(VI) with aging time, except that an unstable Pu(V) immediately reduced to Pu(III).

  15. V6O13 films by control of the oxidation state from aqueous precursor to crystalline phase.

    Science.gov (United States)

    Peys, Nick; Ling, Yun; Dewulf, Daan; Gielis, Sven; De Dobbelaere, Christopher; Cuypers, Daniel; Adriaensens, Peter; Van Doorslaer, Sabine; De Gendt, Stefan; Hardy, An; Van Bael, Marlies K

    2013-01-28

    An aqueous deposition process for V(6)O(13) films is developed whereby the vanadium oxidation state is continuously controlled throughout the entire process. In the precursor stage, a controlled wet chemical reduction of the vanadium(V) source with oxalic acid is achieved and monitored by (51)Vanadium Nuclear Magnetic Resonance ((51)V-NMR) and Ultraviolet-Visible (UV-Vis) spectroscopy. The resulting vanadium(IV) species in the aqueous solution are identified as mononuclear citrato-oxovanadate(IV) complexes by Electron Paramagnetic Resonance (EPR) and Fourier Transform Infra-Red (FTIR) spectroscopy. This precursor is successfully employed for the deposition of uniform, thin films. The optimal deposition and annealing conditions for the formation of crystalline V(6)O(13), including the control of the vanadium oxidation state, are determined through an elaborate study of processing temperature and O(2) partial pressure. To ensure a sub 100 nm adjustable film thickness, a non-oxidative intermediate thermal treatment is carried out at the end of each deposition cycle, allowing maximal precursor decomposition while still avoiding V(IV) oxidation. The resulting surface hydrophilicity, indispensable for the homogeneous deposition of the next layer, is explained by an increased surface roughness and the increased availability of surface vanadyl groups. Crystalline V(6)O(13) with a preferential (002) orientation is obtained after a post deposition annealing in a 0.1% O(2) ambient for thin films with a thickness of 20 nm.

  16. A Semi-Analytical Extraction Method for Interface and Bulk Density of States in Metal Oxide Thin-Film Transistors.

    Science.gov (United States)

    Chen, Weifeng; Wu, Weijing; Zhou, Lei; Xu, Miao; Wang, Lei; Ning, Honglong; Peng, Junbiao

    2018-03-11

    A semi-analytical extraction method of interface and bulk density of states (DOS) is proposed by using the low-frequency capacitance-voltage characteristics and current-voltage characteristics of indium zinc oxide thin-film transistors (IZO TFTs). In this work, an exponential potential distribution along the depth direction of the active layer is assumed and confirmed by numerical solution of Poisson's equation followed by device simulation. The interface DOS is obtained as a superposition of constant deep states and exponential tail states. Moreover, it is shown that the bulk DOS may be represented by the superposition of exponential deep states and exponential tail states. The extracted values of bulk DOS and interface DOS are further verified by comparing the measured transfer and output characteristics of IZO TFTs with the simulation results by a 2D device simulator ATLAS (Silvaco). As a result, the proposed extraction method may be useful for diagnosing and characterising metal oxide TFTs since it is fast to extract interface and bulk density of states (DOS) simultaneously.

  17. A Semi-Analytical Extraction Method for Interface and Bulk Density of States in Metal Oxide Thin-Film Transistors

    Directory of Open Access Journals (Sweden)

    Weifeng Chen

    2018-03-01

    Full Text Available A semi-analytical extraction method of interface and bulk density of states (DOS is proposed by using the low-frequency capacitance–voltage characteristics and current–voltage characteristics of indium zinc oxide thin-film transistors (IZO TFTs. In this work, an exponential potential distribution along the depth direction of the active layer is assumed and confirmed by numerical solution of Poisson’s equation followed by device simulation. The interface DOS is obtained as a superposition of constant deep states and exponential tail states. Moreover, it is shown that the bulk DOS may be represented by the superposition of exponential deep states and exponential tail states. The extracted values of bulk DOS and interface DOS are further verified by comparing the measured transfer and output characteristics of IZO TFTs with the simulation results by a 2D device simulator ATLAS (Silvaco. As a result, the proposed extraction method may be useful for diagnosing and characterising metal oxide TFTs since it is fast to extract interface and bulk density of states (DOS simultaneously.

  18. Non steady-state model for dry oxidation of nuclear wastes metallic containers in long term interim storage conditions

    International Nuclear Information System (INIS)

    Bertrand, Nathalie; Desgranges, Clara; Poquillon, Dominique; Monceau, Daniel

    2006-01-01

    oxidation tests. In a second step, in order to increase the reliability of the long term extrapolations from basic models, a non-steady state numerical model able to take into account several elementary steps is built. The aim is to get a more reliable tool to describe mechanisms that control oxide scale growth in this specific low temperature range. The paper has the following contains: Experimental results; Growth kinetics; Scale morphology; A basic model for kinetics of oxidation; Conclusion of the experimental study; EKINOX: Estimation KINetics OXidation: an advanced model; General description; Equations in the model; Results; Future developments; Conclusion. To summarize, the basic model consists in some extrapolations of available experimental data in the temperature range of interest following simple analytical laws deduced from classical oxidation theories. This leads to a very small oxide scale and thus to the loss of very small amounts of metal even for extrapolations to over 100 years. However, the reliability of this kind of basic models is very poor since it is based on the assumption that a single elementary process controls the oxidation rate. Indeed in the temperature range concerned by long term interim deposit of waste containers, several mechanisms can control the oxidation rate. A numerical model able to take in consideration several growth mechanisms is now in progress. At this stage of development, the originality of the proposed advanced model consists in explicitly calculating the vacancy profiles and treating these as non-conservative species. It is based on an original numerical treatment to correctly and easily describe elimination of vacancies at the metal/oxide interface and thus relative motion between the substrate lattice and the oxide one, even for non-stationary states. It can treat Wagner's model but without the quasi-steady state 'hypothesis or also take into account a partial control of the oxidation process by interfacial reaction. In

  19. Solid-phase extraction of plutonium in various oxidation states from simulated groundwater using N-benzoylphenylhydroxylamine

    International Nuclear Information System (INIS)

    Perevalov, S.A.; Malofeeva, G.I.; Kuzovkina, E.V.; Spivakov, B.Ya.

    2013-01-01

    Solid-phase extraction of plutonium in different individual and mixed oxidation states from simulated groundwater (pH 8.5) was studied. The extraction of plutonium species was carried out in a dynamic mode using DIAPAK C16 cartridges modified by N-benzoylphenylhydroxylamine (BPHA). It was shown that the extent of recovery depends on the oxidation state of plutonium. The extraction of Pu(IV) was at the level of 98-99% regardless of the volume and flow-rate of the sample solution. Pu(V) was extracted by 90-95% and 75-80% from 10- and 100-mL aliquots of the samples, respectively, whereas the extraction of Pu(VI) did not exceed 45-50%. An equimolar mixture of Pu(IV), Pu(V), and Pu(VI) was extracted by 74%. The distribution coefficients (K d ) and kinetic exchange capacities (S) of plutonium in various oxidation states were measured. It was found that during the sorption process, Pu(V) was reduced to Pu(IV) by 80-90% after an hour-long contact with the solid phase. Pu(VI) is reduced to Pu(V) by 34% and to Pu(IV) by 55%. In the case of mixed-valent solution of plutonium, only Pu(V) and Pu(IV) were found in the effluents. (author)

  20. Homoleptic Ce(III) and Ce(IV) Nitroxide Complexes: Significant Stabilization of the 4+ Oxidation State

    Energy Technology Data Exchange (ETDEWEB)

    Bogart, Justin A.; Lewis, Andrew J.; Medling, Scott A.; Piro, Nicholas A.; Carroll, Patrick J.; Booth, Corwin H.; Schelter, Eric J.

    2014-06-25

    Electrochemical experiments performed on the complex Ce-IV[2-((BuNO)-Bu-t)py](4), where [2-((BuNO)-Bu-t)py](-) = N-tert-butyl-N-2-pyridylnitroxide, indicate a 2.51 V stabilization of the 4+ oxidation state of Ce compared to [(Bu4N)-Bu-n](2)[Ce(NO3)(6)] in acetonitrile and a 2.95 V stabilization compared to the standard potential for the ion under aqueous conditions. Density functional theory calculations suggest that this preference for the higher oxidation state is a result of the tetrakis(nitroxide) ligand framework at the Ce cation, which allows for effective electron donation into, and partial covalent overlap with, vacant 4f orbitals with delta symmetry. The results speak to the behavior of CeO2 and related solid solutions in oxygen uptake and transport applications, in particular an inherent local character of bonding that stabilizes the 4+ oxidation state. The results indicate a cerium(IV) complex that has been stabilized to an unprecedented degree through tuning of its ligand-field environment.

  1. High-Pressure Reactivity of Kr and F2—Stabilization of Krypton in the +4 Oxidation State

    Directory of Open Access Journals (Sweden)

    Dominik Kurzydłowski

    2017-10-01

    Full Text Available Since the synthesis of the first krypton compound, several other Kr-bearing connections have been obtained. However, in all of them krypton adopts the +2 oxidation state, in contrast to xenon which forms numerous compounds with an oxidation state as high as +8. Motivated by the possibility of thermodynamic stabilization of exotic compounds with the use of high pressure (exceeding 1 GPa = 10 kbar, we present here theoretical investigations into the chemistry of krypton and fluorine at such large compression. In particular we focus on krypton tetrafluoride, KrF4, a molecular crystal in which krypton forms short covalent bonds with neighboring fluorine atoms thus adopting the +4 oxidation state. We find that this hitherto unknown compound can be stabilized at pressures below 50 GPa. Our results indicate also that, at larger compressions, a multitude of other KrmFn fluorides should be stable, among them KrF which exhibits covalent Kr–Kr bonds. Our results set the stage for future high-pressure synthesis of novel krypton compounds.

  2. Effects of Vanadium Ions in Different Oxidation States on Myosin ATPase Extracted from the Solitary Ascidian, Halocynthia roretzi (Drasche) : Biochemistry

    OpenAIRE

    HITOSHI, MICHIBATA; YUTAKA, ZENKO; KENJI, YAMADA; MASATO, HASEGAWA; TATSURO, TERADA; TAKAHARU, NUMAKUANI; Biological Institute, Faculty of Science, Toyama University; Biological Institute, Faculty of Science, Toyama University; Biological Institute, Faculty of Science, Toyama University; Biological Institute, Faculty of Science, Toyama University; Department of Chemistry, Toyama College of Technology; Marine Biological Station, Tohoku University

    1989-01-01

    Some ascidians are known to accumulate vanadium ion within their tissues by 10^6-fold as that in sea water and store the metal ion in its reduced tetravalent and/or trivalent states. It is also well known that phosphoenzymes are inhibited by pentavalent vanadium ion over a range of 10nM to 1mM. In the present experiment we have therefore examined the effects of vanadium ions in different oxidation states on the activity of myosin ATPase extracted from the mantle of the ascidian, Halocynthia r...

  3. Current emission trends for nitrogen oxides, sulfur dioxide, and volatile organic compounds by month and state: Methodology and results

    International Nuclear Information System (INIS)

    Kohout, E.J.; Miller, D.J.; Nieves, L.A.; Rothman, D.S.; Saricks, C.L.; Stodolsky, F.; Hanson, D.A.

    1990-08-01

    This report presents estimates of monthly sulfur dioxide (SO 2 ), nitrogen oxides (NO x ), and nonmethane voltatile organic compound (VOC) emissions by sector, region, and state in the contiguous United States for the years 1975 through 1988. This work has been funded as part of the National Acid Precipitation Assessment Program's Emissions and Controls Task Group by the US Department of Energy (DOE) Office of Fossil Energy (FE). The DOE project officer is Edward C. Trexler, DOE/FE Office of Planning and Environment

  4. Plutonium uptake by the green alga Scenedesmus obliquus (Turp) Kutz, as a function of isotope and oxidation state

    Energy Technology Data Exchange (ETDEWEB)

    Tkacik, M.F.

    1977-01-01

    This study was designed to determine the effect of plutonium chemical valence state on the availability of small concentrations of /sup 238/Pu and /sup 239/Pu to algae. The uptake experiments involved the green alga Scenedesmus obliquus, grown in batch cultures. Plutonium concentrations accumulated by this alga were linearly related to plutonium concentrations. There was no significant difference (rho = 0.05) in algal plutonium accumulations, on a mass basis, of either /sup 238/Pu or /sup 239/Pu in either Pu/sup +4/ or Pu/sup +6/ oxidation state at the concentrations studied.

  5. Plutonium uptake by the green alga Scenedesmus obliquus (Turp) Kutz, as a function of isotope and oxidation state

    International Nuclear Information System (INIS)

    Tkacik, M.F.

    1977-01-01

    This study was designed to determine the effect of plutonium chemical valence state on the availability of small concentrations of 238 Pu and 239 Pu to algae. The uptake experiments involved the green alga Scenedesmus obliquus, grown in batch cultures. Plutonium concentrations accumulated by this alga were linearly related to plutonium concentrations. There was no significant difference (rho = 0.05) in algal plutonium accumulations, on a mass basis, of either 238 Pu or 239 Pu in either Pu +4 or Pu +6 oxidation state at the concentrations studied

  6. Shock compression of strongly correlated oxides: A liquid-regime equation of state for cerium(IV) oxide

    Science.gov (United States)

    Weck, Philippe F.; Cochrane, Kyle R.; Root, Seth; Lane, J. Matthew D.; Shulenburger, Luke; Carpenter, John H.; Sjostrom, Travis; Mattsson, Thomas R.; Vogler, Tracy J.

    2018-03-01

    The shock Hugoniot for full-density and porous CeO2 was investigated in the liquid regime using ab initio molecular dynamics (AIMD) simulations with Erpenbeck's approach based on the Rankine-Hugoniot jump conditions. The phase space was sampled by carrying out NVT simulations for isotherms between 6000 and 100 000 K and densities ranging from ρ =2.5 to 20 g /cm3 . The impact of on-site Coulomb interaction corrections +U on the equation of state (EOS) obtained from AIMD simulations was assessed by direct comparison with results from standard density functional theory simulations. Classical molecular dynamics (CMD) simulations were also performed to model atomic-scale shock compression of larger porous CeO2 models. Results from AIMD and CMD compression simulations compare favorably with Z-machine shock data to 525 GPa and gas-gun data to 109 GPa for porous CeO2 samples. Using results from AIMD simulations, an accurate liquid-regime Mie-Grüneisen EOS was built for CeO2. In addition, a revised multiphase SESAME-type EOS was constrained using AIMD results and experimental data generated in this work. This study demonstrates the necessity of acquiring data in the porous regime to increase the reliability of existing analytical EOS models.

  7. Signatures of Quantized Energy States in Solution-Processed Ultrathin Layers of Metal-Oxide Semiconductors and Their Devices

    KAUST Repository

    Labram, John G.

    2015-02-13

    Physical phenomena such as energy quantization have to-date been overlooked in solution-processed inorganic semiconducting layers, owing to heterogeneity in layer thickness uniformity unlike some of their vacuum-deposited counterparts. Recent reports of the growth of uniform, ultrathin (<5 nm) metal-oxide semiconductors from solution, however, have potentially opened the door to such phenomena manifesting themselves. Here, a theoretical framework is developed for energy quantization in inorganic semiconductor layers with appreciable surface roughness, as compared to the mean layer thickness, and present experimental evidence of the existence of quantized energy states in spin-cast layers of zinc oxide (ZnO). As-grown ZnO layers are found to be remarkably continuous and uniform with controllable thicknesses in the range 2-24 nm and exhibit a characteristic widening of the energy bandgap with reducing thickness in agreement with theoretical predictions. Using sequentially spin-cast layers of ZnO as the bulk semiconductor and quantum well materials, and gallium oxide or organic self-assembled monolayers as the barrier materials, two terminal electronic devices are demonstrated, the current-voltage characteristics of which resemble closely those of double-barrier resonant-tunneling diodes. As-fabricated all-oxide/hybrid devices exhibit a characteristic negative-differential conductance region with peak-to-valley ratios in the range 2-7.

  8. Geographic Distribution of Ammonia-Oxidizing Archaea along the Kuril Islands in the Western Subarctic Pacific

    Directory of Open Access Journals (Sweden)

    Hongmei Jing

    2017-06-01

    Full Text Available Community composition and abundance of ammonia-oxidizing archaea (AOA in the ocean were affected by different physicochemical conditions, but their responses to physical barriers (such as a chain of islands were largely unknown. In our study, geographic distribution of the AOA from the surface photic zone to the deep bathypelagic waters in the western subarctic Pacific adjacent to the Kuril Islands was investigated using pyrosequencing based on the ammonia monooxygenase subunit A (amoA gene. Genotypes of clusters A and B dominated in the upper euphotic zone and the deep waters, respectively. Quantitative PCR assays revealed that the occurrence and ammonia-oxidizing activity of ammonia-oxidizing archaea (AOA reached their maxima at the depth of 200 m, where a higher diversity and abundance of actively transcribed AOA was observed at the station located in the marginal sea exposed to more terrestrial input. Similar community composition of AOA observed at the two stations adjacent to the Kuril Islands maybe due to water exchange across the Bussol Strait. They distinct from the station located in the western subarctic gyre, where sub-cluster WCAII had a specific distribution in the surface water, and this sub-cluster seemed having a confined distribution in the western Pacific. Habitat-specific groupings of different WCB sub-clusters were observed reflecting the isolated microevolution existed in cluster WCB. The effect of the Kuril Islands on the phylogenetic composition of AOA between the Sea of Okhotsk and the western subarctic Pacific is not obvious, possibly because our sampling stations are near to the Bussol Strait, the main gateway through which water is exchanged between the Sea of Okhotsk and the Pacific. The vertical and horizontal distribution patterns of AOA communities among stations along the Kuril Islands were essentially determined by the in situ prevailing physicochemical gradients along the two dimensions.

  9. Electrocatalytic oxidation of methanol by the [Ru3O(OAc6(py2(CH3OH]3+cluster: improving the metal-ligand electron transfer by accessing the higher oxidation states of a multicentered system

    Directory of Open Access Journals (Sweden)

    Henrique E. Toma

    2010-01-01

    Full Text Available The [Ru3O(Ac6(py2(CH3OH]+ cluster provides an effective electrocatalytic species for the oxidation of methanol under mild conditions. This complex exhibits characteristic electrochemical waves at -1.02, 0.15 and 1.18 V, associated with the Ru3III,II,II/Ru3III,III,II/Ru 3III,III,III /Ru3IV,III,III successive redox couples, respectively. Above 1.7 V, formation of two RuIV centers enhances the 2-electron oxidation of the methanol ligand yielding formaldehyde, in agreement with the theoretical evolution of the HOMO levels as a function of the oxidation states. This work illustrates an important strategy to improve the efficiency of the oxidation catalysis, by using a multicentered redox catalyst and accessing its multiple higher oxidation states.

  10. Control of anode supported SOFCs (solid oxide fuel cells): Part I. mathematical modeling and state estimation within one cell

    International Nuclear Information System (INIS)

    Amedi, Hamid Reza; Bazooyar, Bahamin; Pishvaie, Mahmoud Reza

    2015-01-01

    In this paper, a 3-dimensional mathematical model for one cell of an anode-supported SOFC (solid oxide fuel cells) is presented. The model is derived from the partial differential equations representing the conservation laws of ionic and electronic charges, mass, energy, and momentum. The model is implemented to fully characterize the steady state operation of the cell with countercurrent flow pattern of fuel and air. The model is also used for the comparison of countercurrent with concurrent flow patterns in terms of thermal stress (temperature distribution) and quality of operation (current density). Results reveal that the steady-state cell performance curve and output of simulations qualitatively match experimental data of the literature. Results also demonstrate that countercurrent flow pattern leads to an even distribution of temperature, more uniform current density along the cell and thus is more enduring and superior to the concurrent flow pattern. Afterward, the thorough 3-dimensional model is used for state estimation instead of a real cell. To estimate states, the model is simplified and changed to a 1-dimensional model along flow streams. This simplified model includes uncertainty (because of simplifying assumptions of the model), noise, and disturbance (because of measurements). The behaviors of extended and ensemble Kalman filter as an observer are evaluated in terms of estimating the states and filtering the noises. Results demonstrate that, like extended Kalman filter, ensemble Kalman filter properly estimates the states with 20 sets. - Highlights: • A 3-dimensional model for one cell of SOFC (solid oxide fuel cells) is presented. • Higher voltages and thermal stress in countercurrent than concurrent flow pattern. • State estimation of the cell is examined by ensemble and extended Kalman filters. • Ensemble with 20 sets is as good as extended Kalman filter.

  11. Electrode-Impregnable and Cross-Linkable Poly(ethylene oxide)-Poly(propylene oxide)-Poly(ethylene oxide) Triblock Polymer Electrolytes with High Ionic Conductivity and a Large Voltage Window for Flexible Solid-State Supercapacitors.

    Science.gov (United States)

    Han, Jae Hee; Lee, Jang Yong; Suh, Dong Hack; Hong, Young Taik; Kim, Tae-Ho

    2017-10-04

    We present cross-linkable precursor-type gel polymer electrolytes (GPEs) that have large ionic liquid uptake capability, can easily penetrate electrodes, have high ion conductivity, and are mechanically strong as high-performance, flexible all-solid-state supercapacitors (SC). Our polymer precursors feature a hydrophilic-hydrophobic poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock main-chain structure and trifunctional silane end groups that can be multi-cross-linked with each other through a sol-gel process. The cross-linked solid-state electrolyte film with moderate IL content (200 wt %) shows a well-balanced combination of excellent ionic conductivity (5.0 × 10 -3 S cm -1 ) and good mechanical stability (maximum strain = 194%). Moreover, our polymer electrolytes have various advantages including high thermal stability (decomposition temperature > 330 °C) and the capability to impregnate electrodes to form an excellent electrode-electrolyte interface due to the very low viscosity of the precursors. By assembling our GPE-impregnated electrodes and solid-state GPE film, we demonstrate an all-solid-state SC that can operate at 3 V and provides an improved specific capacitance (112.3 F g -1 at 0.1 A g -1 ), better rate capability (64% capacity retention until 20 A g -1 ), and excellent cycle stability (95% capacitance decay over 10 000 charge/discharge cycles) compared with those of a reference SC using a conventional PEO electrolyte. Finally, flexible SCs with a high energy density (22.6 W h kg -1 at 1 A g -1 ) and an excellent flexibility (>93% capacitance retention after 5000 bending cycles) can successfully be obtained.

  12. State of dog's metabolism in the remote period after the oxide tritium influence

    International Nuclear Information System (INIS)

    Kalistratova, V.S.; Tishchenko, G.S.; Bortnik, L.A.; Nisimov, P.G.; Romanova, I.B.

    2000-01-01

    Influence of tritium oxide on the metabolism by some indices of lipid metabolism (common lipids, β-lipoproteins, cholesterin), protein metabolism (cholinesterase) and carbohydrate metabolism (blood sugar) was studied. It was established that the introduction into organism of tritium oxide in the quantities, which could form lethal and sublethal doses of internal radiation, provoked the main changes of values of mentioned indices of metabolism. The character of metabolism changes in the remote period allows to judge about the development of sclerosis processes which can be the result of radiation-stipulated acceleration of organism aging [ru

  13. Enhanced catalytic hydrogenation activity of Ni/reduced graphene oxide nanocomposite prepared by a solid-state method

    Science.gov (United States)

    Li, Yizhao; Cao, Yali; Jia, Dianzeng

    2018-01-01

    A simple solid-state method has been applied to synthesize Ni/reduced graphene oxide (Ni/rGO) nanocomposite under ambient condition. Ni nanoparticles with size of 10-30 nm supported on reduced graphene oxide (rGO) nanosheets are obtained through one-pot solid-state co-reduction among nickel chloride, graphene oxide, and sodium borohydride. The Ni/rGO nanohybrid shows enhanced catalytic activity toward the reduction of p-nitrophenol (PNP) into p-aminophenol compared with Ni nanoparticles. The results of kinetic research display that the pseudo-first-order rate constant for hydrogenation reaction of PNP with Ni/rGO nanocomposite is 7.66 × 10-3 s-1, which is higher than that of Ni nanoparticles (4.48 × 10-3 s-1). It also presents superior turnover frequency (TOF, 5.36 h-1) and lower activation energy ( E a, 29.65 kJ mol-1) in the hydrogenation of PNP with Ni/rGO nanocomposite. Furthermore, composite catalyst can be magnetically separated and reused for five cycles. The large surface area and high electron transfer property of rGO support are beneficial for good catalytic performance of Ni/rGO nanocomposite. Our study demonstrates a simple approach to fabricate metal-rGO heterogeneous nanostructures with advanced functions.

  14. The state-of-the-art and prospects of the oxidation titration method for the determination of uranium in geological samples

    International Nuclear Information System (INIS)

    Sun Jiayan

    1986-01-01

    The state-of-the-art of the oxidation titration method for the determination of uranium in geological samples is reviewed in some respects such as the prereduction of U(VI), oxidation of U(IV) and the detection of the end-point. Comments are also made on the prospects of further improvements of this method

  15. Example of uranium(IV) insertion within a macrocyclic crown ether with coexistence of the metal in two oxidation states

    Energy Technology Data Exchange (ETDEWEB)

    Bombieri, G; De Paoli, G [Consiglio Nazionale delle Ricerche, Padua (Italy). Lab. di Chimica e Tecnologia dei Radioelementi; Immirzi, A

    1978-01-01

    Reaction of UCl/sub 4/ with 18-crown-6 in tetrahydrofuran yields (UCl/sub 4/)/sub 3/ (18-crown-6)/sub 2/ which on recrystallization in nitromethane, gives a partially oxidized and hydrolyzed product whose structure has been investigated by X-ray diffraction. The compound crystallizes in the orthorhombic system. The cell contains eight UCl/sub 3//sup +/ cations each inserted within a crown molecule and four (UO/sub 2/Cl/sub 3/(OH)(H/sub 2/O))/sup 2 -/anions having a pentagonal bipyramidal structure. Four solvated nitromethane molecules are also present. The compound represents one of the very few examples in which uranium exists in two oxidation states, and the first example in which its insertion within a crown macrocycle has been proved by an X-ray diffraction study.

  16. Remote mixed oxide fabrication facility development. Volume 2. State-of-the-art review of remote maintenance system technology

    International Nuclear Information System (INIS)

    Horgos, R.M.; Masch, M.L.

    1979-06-01

    This report provides a state-of-the-art review of remote systems technology, which includes manipulators, process connectors, vision systems and specialized process systems. A proposed mixed oxide fuel fabrication facility was reviewed and evaluated for identification of major remote maintenance and repair tasks. The technological areas were evaluated on the basis of their suitability or applicability for remote maintenance and repair of a proposed fully remote operating mixed oxide fuel fabrication facility. A technological base exists from which the design criteria for a reliable, remote operating facility can be established. Commercially available systems and components, along with those remote technologies now in development, will require modifications to adapt them to specific plant designs and requirements

  17. Electrochemistry and time dependent DFT study of a (vinylenedithio)-TTF derivative in different oxidation states

    NARCIS (Netherlands)

    Halpin, Yvonne; Schulz, Martin; Brooks, Andrew C.; Browne, Wesley R.; Wallis, John D.; Gonzalez, Leticia; Day, Peter; Vos, Johannes G.

    2013-01-01

    The electrochemical and spectroelectrochemical properties of a bis-pyrid-4-yl functionalised vinylenedithio-TFF derivative, 1, in solution are reported. The compound was immobilised on a Pt electrode and the resulting layers formed were investigated using electrochemical techniques. Two oxidation

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

    International Nuclear Information System (INIS)

    Veronda, Brenda; Dingens, Matthew

    2007-01-01

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

  19. Influence of Structure and Charge State on the Mechanism of CO Oxidation on Gold Clusters

    Science.gov (United States)

    Johnson, Grant; Burgel, Christian; Reilly, Nelly; Mitric, Roland; Kimble, Michele; Tyo, Eric; Castleman, A. W.; Bonacic-Koutecky, Vlasta

    2008-05-01

    Gas-phase reactivity experiments and high level theoretical calculations have been employed to study the interaction of both positively and negatively charged gold oxide clusters with carbon monoxide (CO). We demonstrate that for negatively charged clusters CO is oxidized to CO2 by an Eley-Ridel-like (ER-) mechanism involving the attack of CO on oxygen rather than gold. In contrast, for positively charged clusters, the oxidation reaction may also occur by a Langmuir-Hinshelwood-like (LH-) mechanism involving the initial binding of CO to a gold atom followed by subsequent migration to an oxygen site. The LH mechanism is made possible through the large energy gain associated with the adsorption of two CO molecules onto cationic gold clusters. Structure-reactivity relationships are also established which demonstrate that terminally bound oxygen atoms are the most active sites for CO oxidation. Bridge bonded oxygen atoms and molecularly bound O2 units are shown to be inert. We also establish an inverse relationship between the binding energy of CO to gold clusters and the energy of the clusters lowest unoccupied molecular orbital (LUMO).

  20. A study of relaxation mechanisms in the A{sup 2}{Sigma}{sup +} state of nitric oxide by time resolved double resonant polarization spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Stampanoni-Panariello, A; Bombach, R; Hemmerling, B; Hubschmid, W [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    Double resonant polarization labeling spectroscopy is applied to detect nitric oxide in flames and to characterize rotational energy transfer and orientation changing collisions in its first excited electronic state. (author) 4 figs., 3 refs.

  1. A detailed study on the transition from the blocked to the superparamagnetic state of reduction-precipitated iron oxide nanoparticles

    International Nuclear Information System (INIS)

    Witte, K.; Bodnar, W.; Mix, T.; Schell, N.; Fulda, G.; Woodcock, T.G.; Burkel, E.

    2016-01-01

    Magnetic iron oxide nanoparticles were prepared by salt-assisted solid-state chemical precipitation method with alternating fractions of the ferric iron content. The physical properties of the precipitated nanoparticles mainly consisting of magnetite were investigated by means of transmission electron microscopy, high energy X-ray diffraction, vibrating sample magnetometry and Mössbauer spectroscopy. With particle sizes ranging from 16.3 nm to 2.1 nm, a gradual transition from the blocked state to the superparamagnetic state was observed. The transition was described as a dependence of the ferric iron content used during the precipitation. Composition, mean particle size, coercivity, saturation polarisation, as well as hyperfine interaction parameters and their evolution were studied systematically over the whole series of iron oxide nanoparticles. - Highlights: • Study of superparamagnetic transition of magnetite varying ferric iron content. • Coercivity is mainly influenced by the particle size. • Saturation polarisation influenced by the goethite content and the particle size. • Number of vacancies tend to increase with increasing ferric iron content. • Fe 3 O 4 B-sites are stronger effected by the reduction of particle size than A-sites.

  2. All-solid-state flexible microsupercapacitors based on reduced graphene oxide/multi-walled carbon nanotube composite electrodes

    Science.gov (United States)

    Mao, Xiling; Xu, Jianhua; He, Xin; Yang, Wenyao; Yang, Yajie; Xu, Lu; Zhao, Yuetao; Zhou, Yujiu

    2018-03-01

    All-solid-state flexible microsupercapacitors have been intensely investigated in order to meet the rapidly growing demands for portable microelectronic devices. Herein, we demonstrate a facile, readily scalable and cost-effective laser induction process for preparing reduced graphene oxide/multi-walled carbon nanotube composite, which can be used as the interdigital electrodes in microsupercapacitors. The obtained composite exhibits high volumetric capacitance about 49.35 F cm-3, which is nearly 5 times higher than that of the pristine reduced graphene oxide film in aqueous 1.0 M H2SO4 solution (measured at a current density of 5 A cm-3 in a three-electrode testing). Additionally, an all-solid-state flexible microsupercapacitor employing these composite electrodes with PVA/H3PO4 gel electrolyte delivers high volumetric energy density of 6.47 mWh cm-3 at 10 mW cm-3 under the current density of 20 mA cm-3 as well as achieve excellent cycling stability retaining 88.6% of its initial value and outstanding coulombic efficiency after 10,000 cycles. Furthermore, the microsupercapacitors array connected in series/parallel can be easily adjusted to achieve the demands in practical applications. Therefore, this work brings a promising new candidate of prepare technologies for all-solid-state flexible microsupercapacitors as miniaturized power sources used in the portable and wearable electronics.

  3. Effect of charged deep states in hydrogenated amorphous silicon on the behavior of iron oxides nanoparticles deposited on its surface

    International Nuclear Information System (INIS)

    Gmucova, Katarina; Weis, Martin; Nadazdy, Vojtech; Capek, Ignac; Satka, Alexander; Chitu, Livia; Cirak, Julius; Majkova, Eva

    2008-01-01

    Langmuir-Blodgett technique has been used for the deposition of ordered two-dimensional arrays of iron oxides (Fe 3 O 4 /Fe 2 O 3 ) nanoparticles onto the photovoltaic hydrogenated amorphous silicon (a-Si:H) thin film. Electric field at the a-Si:H/iron oxides nanoparticles interface was directly in the electrochemical cell modified by light soaking and bias voltage (negative or positive) pretreatment resulting in the change of the dominant type of charged deep states in the a-Si:H layer. Induced reversible changes in the nanoparticle redox behavior have been observed. We suggest two possible explanations of the data obtained, both of them are needed to describe measured electrochemical signals. The first one consists in the electrocatalytical effect caused by the defect states (negatively or positively charged) in the a-Si:H layer. The second one consists in the possibility to manipulate the nanoparticle cores in the prepared structure immersed in aqueous solution via the laser irradiation under specific bias voltage. In this case, the nanoparticle cores are assumed to be covered with surface clusters of heterovalent complexes created onto the surface regions with prevailing ferrous or ferric valency. Immersed in the high viscosity surrounding composed of the wet organic nanoparticle envelope these cores are able to perform a field-assisted pivotal motion. The local electric field induced by the deep states in the a-Si:H layer stabilizes their 'orientation ordering' in an energetically favourable position

  4. Hemoglobin redux: combining neutron and X-ray diffraction with mass spectrometry to analyse the quaternary state of oxidized hemoglobins

    Energy Technology Data Exchange (ETDEWEB)

    Mueser, Timothy C., E-mail: timothy.mueser@utoledo.edu; Griffith, Wendell P. [Department of Chemistry, University of Toledo, Toledo, OH 43606 (United States); Kovalevsky, Andrey Y. [Bioscience Division, MS M888, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Guo, Jingshu; Seaver, Sean [Department of Chemistry, University of Toledo, Toledo, OH 43606 (United States); Langan, Paul [Department of Chemistry, University of Toledo, Toledo, OH 43606 (United States); Bioscience Division, MS M888, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Hanson, B. Leif [Department of Chemistry, University of Toledo, Toledo, OH 43606 (United States)

    2010-11-01

    X-ray and neutron diffraction studies of cyanomethemoglobin are being used to evaluate the structural waters within the dimer–dimer interface involved in quaternary-state transitions. Improvements in neutron diffraction instrumentation are affording the opportunity to re-examine the structures of vertebrate hemoglobins and to interrogate proton and solvent position changes between the different quaternary states of the protein. For hemoglobins of unknown primary sequence, structural studies of cyanomethemoglobin (CNmetHb) are being used to help to resolve sequence ambiguity in the mass spectra. These studies have also provided additional structural evidence for the involvement of oxidized hemoglobin in the process of erythrocyte senescence. X-ray crystal studies of Tibetan snow leopard CNmetHb have shown that this protein crystallizes in the B state, a structure with a more open dyad, which possibly has relevance to RBC band 3 protein binding and erythrocyte senescence. R-state equine CNmetHb crystal studies elaborate the solvent differences in the switch and hinge region compared with a human deoxyhemoglobin T-state neutron structure. Lastly, comparison of histidine protonation between the T and R state should enumerate the Bohr-effect protons.

  5. Nitric oxide in plants: an assessment of the current state of knowledge

    DEFF Research Database (Denmark)

    Mur, Luis A J; Mandon, Julien; Persijn, Stefan

    2013-01-01

    Background and aims After a series of seminal works during the last decade of the 20th century nitric oxide (NO) is now firmly placed in the pantheon of plant signals. NO acts in plant-microbe interactions, responses to abiotic stress, stomatal regulation and a range of developmental processes...... of NO production from DEANO (diethylamine nitric oxide), S-nitrosoglutathione (GSNO) and sodium nitroprusside (SNP) following infiltration of tobacco leaves which could aid workers in their experiments. Further, based on current data it is difficult to define a bespoke plant NO signalling pathway, but rather....... By considering the recent advances in plant NO biology, this review will highlight certain key aspects that require further attention. Scope and conclusions The following questions will be considered. Whilst cytosolic nitrate reductase is an important source of NO, the contributions of other mechanisms...

  6. The discrimination of the oxidation states of neptunium in sodium hydroxide solutions by means of chromatography on alumina

    International Nuclear Information System (INIS)

    Shiokawa, Yoshinobu; Yamana, Hajimu; Sato, Akiko; Suzuki, Shin

    1982-01-01

    A method of discriminating the oxidation states of Np in a NaOH solution by means of chromatography on alumina is proposed. In a NaOH solution of 0.5 - 1.7 M (1 M = 1 mol dm - 3 ), the separation of Np (VI) from Np (VII) can be made effectively by means of chromatography on alumina. Only a little Np (VI) is adsorbed on alumina the Np (VII) adsorbed to some extent, and the Np (V), strongly, under the same conditions. By applying this chromatographic method, the method of preparing Np (VI) and Np (VII) of a tracer quantity in 1 M NaOH is established. (author)

  7. Solid-state Water-mediated Transport Reduction of Nanostructured Iron Oxides

    International Nuclear Information System (INIS)

    Smirnov, Vladimir M.; Povarov, Vladimir G.; Voronkov, Gennadii P.; Semenov, Valentin G.; Murin, Igor' V.; Gittsovich, Viktor N.; Sinel'nikov, Boris M.

    2001-01-01

    The Fe 2+ /Fe 3+ ratio in two-dimensional iron oxide nanosructures (nanolayers with a thickness of 0.3-1.5 nm on silica surface) may be precisely controlled using the transport reduction (TR) technique. The species ≡-O-Fe(OH) 2 and (≡Si-O-) 2 -FeOH forming the surface monolayer are not reduced at 400-600 deg. C because of their covalent bonding to the silica surface, as demonstrated by Moessbauer spectroscopy. Iron oxide microparticles (microstructures) obtained by the impregnation technique, being chemically unbound to silica, are subjected to reduction at T ≥ 500 deg. C with formation of metallic iron in the form of α-Fe. Transport reduction of supported nanostructures (consisting of 1 or 4 monolayers) at T ≥ 600 deg. C produces bulk iron(II) silicate and metallic iron phases. The structural-chemical transformations occurring in transport reduction of supported iron oxide nanolayers are proved to be governed by specific phase processes in the nanostructures themselves

  8. Constitutively elevated salicylic acid levels alter photosynthesis and oxidative state but not growth in transgenic populus.

    Science.gov (United States)

    Xue, Liang-Jiao; Guo, Wenbing; Yuan, Yinan; Anino, Edward O; Nyamdari, Batbayar; Wilson, Mark C; Frost, Christopher J; Chen, Han-Yi; Babst, Benjamin A; Harding, Scott A; Tsai, Chung-Jui

    2013-07-01

    Salicylic acid (SA) has long been implicated in plant responses to oxidative stress. SA overproduction in Arabidopsis thaliana leads to dwarfism, making in planta assessment of SA effects difficult in this model system. We report that transgenic Populus tremula × alba expressing a bacterial SA synthase hyperaccumulated SA and SA conjugates without negative growth consequences. In the absence of stress, endogenously elevated SA elicited widespread metabolic and transcriptional changes that resembled those of wild-type plants exposed to oxidative stress-promoting heat treatments. Potential signaling and oxidative stress markers azelaic and gluconic acids as well as antioxidant chlorogenic acids were strongly coregulated with SA, while soluble sugars and other phenylpropanoids were inversely correlated. Photosynthetic responses to heat were attenuated in SA-overproducing plants. Network analysis identified potential drivers of SA-mediated transcriptome rewiring, including receptor-like kinases and WRKY transcription factors. Orthologs of Arabidopsis SA signaling components NON-EXPRESSOR OF PATHOGENESIS-RELATED GENES1 and thioredoxins were not represented. However, all members of the expanded Populus nucleoredoxin-1 family exhibited increased expression and increased network connectivity in SA-overproducing Populus, suggesting a previously undescribed role in SA-mediated redox regulation. The SA response in Populus involved a reprogramming of carbon uptake and partitioning during stress that is compatible with constitutive chemical defense and sustained growth, contrasting with the SA response in Arabidopsis, which is transient and compromises growth if sustained.

  9. Molecular beam epitaxy growth of niobium oxides by solid/liquid state oxygen source and lithium assisted metal-halide chemistry

    Science.gov (United States)

    Tellekamp, M. Brooks; Greenlee, Jordan D.; Shank, Joshua C.; Doolittle, W. Alan

    2015-09-01

    In order to consistently grow high quality niobium oxides and lithium niobium oxides, a novel solid/liquid state oxygen source, LiClO4, has been implemented in a molecular beam epitaxy (MBE) system. LiClO4 is shown to decompose into both molecular and atomic oxygen upon heating. This allows oxidation rates similar to that of molecular oxygen but at a reduced overall beam flux, quantified by in situ Auger analysis. LiClO4 operation is decomposition limited to less than 400 °C, and other material limitations are identified. The design of a custom near-ambient NbCl5 effusion cell is presented, which improves both short and long term stability. Films of Nb oxidation state +2, +3, and +5 are grown using these new tools, including the multi-functional sub-oxide LiNbO2.

  10. Determination of the specific surface energy of oxides and glasses in the solid-state

    International Nuclear Information System (INIS)

    Andryushechkin, S.; Karpman, M.

    2000-01-01

    The production and application of coatings on glasses are used widely in technology. The coatings on glass are used for the regulation of optical, decorative, conducting and other technological and physical properties of glass. In particular, it is important to mention the application of glass fibres for the development of composite materials. However, the specific surface energy of glass and, consequently, its adhesion characteristics are relatively low. The values of these characteristics can be changed by the application of different metallic and nonmetallic coatings is characterised by high surface energy. To produce metallic coatings with the required adhesion strength of glass, it is necessary to have information on the specific surface energy of inorganic glass of different chemical composition. The determination of the relationships between the properties and composition of glass is one of the fundamental problems. At present, a large amount of investigations have been carried out into the investigations of the properties of glass in relation to its composition. However, the problem of establishment of relationships between the properties and composition of glass are especially difficult when examining multicomponent systems (technical glass). It is therefore, in to analyse in each case the properties of not the entire system has a whole but the variation of the properties with temperature of the individual components included in the system, the subsequent application of the additivity principle. The large majority of the glasses represent combinations of oxides of the elements of groups I-III and oxides of the transition metals, forming the mixtures, solid solutions of chemical compounds in the glass production process. Thus, analysis of the characteristics of oxides of the alkali, alkali-earth and transition metals makes it possible to obtain initial data for the evaluation of the surface energy, density, molecular mass of glass containing these oxides

  11. Iron oxides as pedoenvironmental indicators: state of the art, answers and questions (Philippe Duchaufour Medal Lecture)

    Science.gov (United States)

    Torrent, J.

    2012-04-01

    The colour and magnetic properties of soils largely reflect the content and mineralogy of their iron oxides, which in turn relate to the physical, chemical and biological characteristics of the soil environment. For more than 50 years, soil mineralogists and chemists have collected data for iron oxides in soils formed in widely different environments and tried to understand the complex nature of the different suites and formation pathways for these minerals via laboratory experiments. The discovery of ferrihydrite —the poorly crystalline precursor of most Fe oxides— in 1971, and the recognition of its common presence in soils, raised interest in deciphering the environmental factors that affect its transformation into goethite and hematite, the two most abundant crystalline iron oxides in soil. Field observations were consistent with laboratory experiments in which temperature, water activity, pH, foreign ions and organic matter were found to play a key role in the crystallization of ferrihydrite. Thus, the hematite/(hematite + goethite) ratio increased with increasing temperature and also with the likelihood of seasonal soil drying. Exploiting this ratio as a (pedo)environment indicator is, however, not devoid of problems derived from insufficient knowledge of the interactions between the influential chemical variables, difficulties in quantifying the two minerals and changes brought about by reductive dissolution. Soil formation usually leads to magnetic enhancement as a result of the production of magnetite and/or maghemite, which are ferrimagnetic iron oxides, and, possibly, an ordered ferrimagnetic ferrihydrite, as suggested by recent laboratory experiments. The concentration of pedogenic ferrimagnets as estimated via proxies such as magnetic susceptibility or frequency-dependent magnetic susceptibility has been found to relate to climate variables [particularly (paleo)rainfall] in many studies reported over the last 30 years. However, extracting accurate

  12. Analyzer for measurement of nitrogen oxide concentration by ozone content reduction in gas using solid state chemiluminescent sensor

    Science.gov (United States)

    Chelibanov, V. P.; Ishanin, G. G.; Isaev, L. N.

    2014-05-01

    Role of nitrogen oxide in ambient air is described and analyzed. New method of nitrogen oxide concentration measurement in gas phase is suggested based on ozone concentration measurement with titration by nitrogen oxide. Research of chemiluminescent sensor composition is carried out on experimental stand. The sensor produced on the base of solid state non-activated chemiluminescent composition is applied as ozone sensor. Composition is put on the surface of polymer matrix with developed surface. Sensor compositions includes gallic acid with addition of rodamine-6G. Model of interaction process between sensor composition and ozone has been developed, main products appeared during reaction are identified. The product determining the speed of luminescense appearance is found. This product belongs to quinone class. Then new structure of chemiluminescent composition was suggested, with absence of activation period and with high stability of operation. Experimental model of gas analyzer was constructed and operation algorithm was developed. It was demonstrated that developed NO measuring instrument would be applied for monitoring purposes of ambient air. This work was partially financially supported by Government of Russian Federation, Grant 074-U01

  13. Oxidation states by X-ray fluorescence and electron probe microanalysis techniques

    International Nuclear Information System (INIS)

    Vazquez, Cristina; Riveros, J.A.

    1987-01-01

    Many years ago, several studies showed the effect of a chemical state in X-ray spectra. The effect, however, has rarely been utilized in quantitative chemical analysis. The purpose of this work is to show observed shifts due to different chemical states in iron compounds. (Author) [es

  14. State-of-the-art Sn2+-based ternary oxides as photocatalysts for water splitting: electronic structures and optoelectronic properties

    KAUST Repository

    Noureldine, Dalal

    2016-09-19

    Developing visible light responsive metal oxide photocatalysts is a challenge that must be conquered to achieve high efficiency for water splitting or hydrogen evolution reactions. Valence band engineering is possible by forming ternary oxides using the combination of a metal cation with an s2d10 electronic configuration and a transition metal oxide with a d0 configuration. Many (Sn2+, Bi3+, Pb2+)-based ternary metal oxide photocatalysts have been reported for hydrogen and/or oxygen evolution under visible irradiation. Sn2+-based materials have attracted particular attention because tin is inexpensive, abundant and more environmentally friendly than lead or bismuth. In this review, we provide a fruitful library for Sn2+-based photocatalysts that have been reported to evolve hydrogen using sacrificial reagents, including SnNb2O6, Sn2Nb2O7, SnTaxNb2−xO6, SnTa2O6, Sn2Ta2O7, SnWO4 (α and β phases), SnSb2O6·nH2O, and Sn2TiO4. The synthesis method used in the literature and the resultant morphology and crystal structure of each compound are discussed. The density functional theory (DFT) calculations of the electronic structure and density of states are provided, and the consequent optoelectronic properties such as band gap, nature of the bandgap, dielectric constant, and effective masses are summarized. This review will help highlight the main challenges for Sn2+-based materials.

  15. State-of-the-art Sn2+-based ternary oxides as photocatalysts for water splitting: electronic structures and optoelectronic properties

    KAUST Repository

    Noureldine, Dalal; Takanabe, Kazuhiro

    2016-01-01

    Developing visible light responsive metal oxide photocatalysts is a challenge that must be conquered to achieve high efficiency for water splitting or hydrogen evolution reactions. Valence band engineering is possible by forming ternary oxides using the combination of a metal cation with an s2d10 electronic configuration and a transition metal oxide with a d0 configuration. Many (Sn2+, Bi3+, Pb2+)-based ternary metal oxide photocatalysts have been reported for hydrogen and/or oxygen evolution under visible irradiation. Sn2+-based materials have attracted particular attention because tin is inexpensive, abundant and more environmentally friendly than lead or bismuth. In this review, we provide a fruitful library for Sn2+-based photocatalysts that have been reported to evolve hydrogen using sacrificial reagents, including SnNb2O6, Sn2Nb2O7, SnTaxNb2−xO6, SnTa2O6, Sn2Ta2O7, SnWO4 (α and β phases), SnSb2O6·nH2O, and Sn2TiO4. The synthesis method used in the literature and the resultant morphology and crystal structure of each compound are discussed. The density functional theory (DFT) calculations of the electronic structure and density of states are provided, and the consequent optoelectronic properties such as band gap, nature of the bandgap, dielectric constant, and effective masses are summarized. This review will help highlight the main challenges for Sn2+-based materials.

  16. Correlation of Mn charge state with the electrical resistivity of Mn doped indium tin oxide thin films

    KAUST Repository

    Kumar, S. R. Sarath; Hedhili, Mohamed N.; Alshareef, Husam N.; Kasiviswanathan, S.

    2010-01-01

    Correlation of charge state of Mn with the increase in resistivity with Mn concentration is demonstrated in Mn-doped indium tin oxide films. Bonding analysis shows that Mn 2p3/2 core level can be deconvoluted into three components corresponding to Mn2+ and Mn4+ with binding energies 640.8 eV and 642.7 eV, respectively, and a Mn2+ satellite at ∼5.4 eV away from the Mn2+ peak. The presence of the satellite peak unambiguously proves that Mn exists in the +2 charge state. The ratio of concentration of Mn2+ to Mn4+ of ∼4:1 suggests that charge compensation occurs in the n-type films causing the resistivity increase.

  17. Correlation of Mn charge state with the electrical resistivity of Mn doped indium tin oxide thin films

    KAUST Repository

    Kumar, S. R. Sarath

    2010-09-15

    Correlation of charge state of Mn with the increase in resistivity with Mn concentration is demonstrated in Mn-doped indium tin oxide films. Bonding analysis shows that Mn 2p3/2 core level can be deconvoluted into three components corresponding to Mn2+ and Mn4+ with binding energies 640.8 eV and 642.7 eV, respectively, and a Mn2+ satellite at ∼5.4 eV away from the Mn2+ peak. The presence of the satellite peak unambiguously proves that Mn exists in the +2 charge state. The ratio of concentration of Mn2+ to Mn4+ of ∼4:1 suggests that charge compensation occurs in the n-type films causing the resistivity increase.

  18. Chemical state analysis of oxide thin films using a high resolution double crystal X-ray fluorescence spectrometer

    International Nuclear Information System (INIS)

    Masuda, Hirohisa; Morinaga, Kenji; Ohta, Yoshio.

    1995-01-01

    The chemical state analysis of r.f.-sputtered amorphous oxide thin films was determined by a high resolution X-ray fluorescence spectrometer with double crystals. The polymerization degree of silicate anions in the silicate film was as same as a target (α-Quartz). The oxygen coordination number of Al 3+ ions in the aluminate film was different from a target (α-Al 2 O 3 ), and it was a mixture of 4 and 6 in a spinel-like structure. In CaO-SiO 2 and CaO-Al 2 O 3 films, when the film thickness is thin at the beginning of sputtering, the composition of films are in the shortage of CaO. But when the film thickness become thicker, the composition of films become as same as the target. From the results above, the chemical state of films and their variations with film thickness can be clarified by using the apparatus. (author)

  19. Study of the oxidation state of arsenic and uranium in individual particles from uranium mine tailings, Hungary

    International Nuclear Information System (INIS)

    Alsecz, A.; Osan, J.; Palfalvi, J.; Torok, Sz.; Sajo, I.; Mathe, Z.; Simon, R.; Falkenberg, G.

    2007-01-01

    Uranium ore mining and milling have been terminated in the Mecsek Mountains (southwest Hungary) in 1997. Mine tailings ponds are located between two important water bases, which are resources of the drinking water of the city of Pecs and the neighbouring villages. The average U concentration of the tailings material is 71.73 μg/g, but it is inhomogeneous. Some microscopic particles contain orders of magnitude more U than the rest of the tailings material. Other potentially toxic elements are As and Pb of which chemical state is important to estimate mobility, because in mobile form they can risk the water basis and the public health. Individual U-rich particles were selected with solid state nuclear track detector (SSNTD) and after localisation the particles were investigated by synchrotron radiation based microanalytical techniques. The distribution of elements over the particles was studied by micro beam X-ray fluorescence (μ-XRF) and the oxidation state of uranium and arsenic was determined by micro X-ray absorption near edge structure (μ-XANES) spectroscopy. Some of the measured U-rich particles were chosen for studying the heterogeneity with μ-XRF tomography. Arsenic was present mainly in As(V) and uranium in U(VI) form in the original uranium ore particles, but in the mine tailings samples uranium was present mainly in the less mobile U(IV) form. Correlation was found between the oxidation state of As and U in the same analyzed particles. These results suggest that dissolution of uranium is not expected in short term period. (authors)

  20. An unusual high-spin ground state of Co3+ in octahedral coordination in brownmillerite-type cobalt oxide.

    Science.gov (United States)

    Istomin, S Ya; Tyablikov, O A; Kazakov, S M; Antipov, E V; Kurbakov, A I; Tsirlin, A A; Hollmann, N; Chin, Y Y; Lin, H-J; Chen, C T; Tanaka, A; Tjeng, L H; Hu, Z

    2015-06-21

    The crystal and magnetic structures of brownmillerite-like Sr(2)Co(1.2)Ga(0.8)O(5) with a stable Co(3+) oxidation state at both octahedral and tetrahedral sites are refined using neutron powder diffraction data collected at 2 K (S.G. Icmm, a = 5.6148(6) Å, b = 15.702(2) Å, c = 5.4543(6) Å; R(wp) = 0.0339, R(p) = 0.0443, χ(2) = 0.775). The very large tetragonal distortion of CoO(6) octahedra (1.9591(4) Å for Co-O(eq) and 2.257(6) Å for Co-O(ax)) could be beneficial for the stabilization of the long-sought intermediate-spin state of Co(3+) in perovskite-type oxides. However, the large magnetic moment of octahedral Co(3+) (3.82(7)μ(B)) indicates the conventional high-spin state of Co(3+) ions, which is further supported by the results of a combined theoretical and experimental soft X-ray absorption spectroscopy study at the Co-L(2,3) edges on Sr(2)Co(1.2)Ga(0.8)O(5). A high-spin ground state of Co(3+) in Sr(2)Co(1.2)Ga(0.8)O(5) resulted in much lower in comparison with a LaCoO(3) linear thermal expansion coefficient of 13.1 ppm K(-1) (298-1073 K) determined from high-temperature X-ray powder diffraction data collected in air.

  1. Electronic States of High-k Oxides in Gate Stack Structures

    Science.gov (United States)

    Zhu, Chiyu

    In this dissertation, in-situ X-ray and ultraviolet photoemission spectroscopy have been employed to study the interface chemistry and electronic structure of potential high-k gate stack materials. In these gate stack materials, HfO2 and La2O3 are selected as high-k dielectrics, VO2 and ZnO serve as potential channel layer materials. The gate stack structures have been prepared using a reactive electron beam system and a plasma enhanced atomic layer deposition system. Three interrelated issues represent the central themes of the research: 1) the interface band alignment, 2) candidate high-k materials, and 3) band bending, internal electric fields, and charge transfer. 1) The most highlighted issue is the band alignment of specific high-k structures. Band alignment relationships were deduced by analysis of XPS and UPS spectra for three different structures: a) HfO2/VO2/SiO2/Si, b) HfO 2-La2O3/ZnO/SiO2/Si, and c) HfO 2/VO2/ HfO2/SiO2/Si. The valence band offset of HfO2/VO2, ZnO/SiO2 and HfO 2/SiO2 are determined to be 3.4 +/- 0.1, 1.5 +/- 0.1, and 0.7 +/- 0.1 eV. The valence band offset between HfO2-La2O3 and ZnO was almost negligible. Two band alignment models, the electron affinity model and the charge neutrality level model, are discussed. The results show the charge neutrality model is preferred to describe these structures. 2) High-k candidate materials were studied through comparison of pure Hf oxide, pure La oxide, and alloyed Hf-La oxide films. An issue with the application of pure HfO2 is crystallization which may increase the leakage current in gate stack structures. An issue with the application of pure La2O3 is the presence of carbon contamination in the film. Our study shows that the alloyed Hf-La oxide films exhibit an amorphous structure along with reduced carbon contamination. 3) Band bending and internal electric fields in the gate stack structure were observed by XPS and UPS and indicate the charge transfer during the growth and process. The oxygen

  2. Influence of oxidation state on the absorption of plutonium from the gastrointestinal tract

    International Nuclear Information System (INIS)

    Sullivan, M.F.; Ryan, J.L.; Gorham, L.S.; McFadden, K.M.

    1979-01-01

    Rats and guinea pigs treated intragastrically with either IV- or VI-valent 238 Pu showed no appreciable difference in absorption. Nitric acid solutions of 239 Pu (pH 2) were also administered to fasted and fed rats. When an oxidant (K 2 Cr 2 O 7 ) was present in the solution gavaged to fasted rats, absorption increased 34-fold. However, when 239 Pu VI was administered to fed rats in the absence of dichromate, there was no appreciable difference between the absorption of 239 Pu VI and 239 Pu IV

  3. Micro-XANES measurements on experimental spinels and the oxidation state of vanadium in coexisting spinel and silicate melt

    International Nuclear Information System (INIS)

    Righter, K.; Sutton, S.R.; Newville, M.; Le, L.; Schwandt, C.S.

    2006-01-01

    We show that experimental spinels coexisting with silicate melt always have lower valence vanadium, and that spinels typically have 3+, whereas the coexisting melt has 4+ or 5+. Implications of these results for planetary basalts will be discussed. Spinel can be a significant host phase for V which has multiple oxidation states V 2+ , V 3+ , V 4+ or V 5+ at oxygen fugacities relevant to natural systems. The magnitude of D(V) spinel/melt is known to be a function of composition, temperature and fO 2 , but the uncertainty of the oxidation state under the range of natural conditions has made elusive a thorough understanding of D(V) spinel/melt. For example, V 3+ is likely to be stable in spinels, based on exchange with Al in experiments in the CaO-MgO-Al 2 O 3 -SiO 2 system. On the other hand, it has been argued that V 4+ will be stable across the range of natural oxygen fugacities in nature. In order to build on our previous work in more oxidized systems, we have carried out experiments at relatively reducing conditions from the FMQ buffer to 2 log fO 2 units below the IW buffer. These spinel-melt pairs, where V is present in the spinel at natural levels (∼300 ppm V), were analyzed using an electron microprobe at NASA-JSC and mi-cro-XANES at the Advanced Photon Source at Argonne National Laboratory. The new results will be used together with previous results to understand the valence of V in spinel-melt systems across 12 orders of magnitude of oxygen fugacity, and with application to natural systems.

  4. Solid-state voltammetry-based electrochemical immunosensor for Escherichia coli using graphene oxide-Ag nanoparticle composites as labels.

    Science.gov (United States)

    Jiang, Xiaochun; Chen, Kun; Wang, Jing; Shao, Kang; Fu, Tao; Shao, Feng; Lu, Donglian; Liang, Jiangong; Foda, M Frahat; Han, Heyou

    2013-06-21

    A new electrochemical immunosensor based on solid-state voltammetry was fabricated for the detection of Escherichia coli (E. coli) by using graphene oxide-Ag nanoparticle composites (P-GO-Ag) as labels. To construct the platform, Au nanoparticles (AuNPs) were first self-assembled on an Au electrode surface through cysteamine and served as an effective matrix for antibody (Ab) attachment. Under a sandwich-type immunoassay format, the analyte and the probe (P-GO-Ag-Ab) were successively captured onto the immunosensor. Finally, the bonded AgNPs were detected through a solid-state redox process in 0.2 M of KCl solution. Combining the advantages of the high-loading capability of graphene oxide with promoted electron-transfer rate of AuNPs, this immunosensor produced a 26.92-fold signal enhancement compared with the unamplified protocol. Under the optimal conditions, the immunosensor exhibited a wide linear dependence on the logarithm of the concentration of E. coli ranging from 50 to 1.0 × 10(6) cfu mL(-1) with a detection limit of 10 cfu mL(-1). Moreover, as a practical application, the proposed immunosensor was used to monitor E. coli in lake water with satisfactory results.

  5. Chromium Oxidation State in Planetary Basalts: Oxygen Fugacity Indicator and Critical Variable for Cr-Spinel Stability

    Science.gov (United States)

    Bell, A. S.; Burger, P. V.; Le, Loan; Papike, J. J.; Jone, J.; Shearer, C. K.

    2014-01-01

    Cr is a ubiquitous and relatively abundant minor element in basaltic, planetary magmas. At the reduced oxidation states (oxidation state of Cr in in silicate melts. Here we present a series of 1-bar gas mixing experiments performed with a Fe-rich basaltic melt in which have determined the Cr redox ratio of the melt at over a range of fO2 values by measuring this quantity in olivine with X-ray Absorption Near Edge Spectroscopy (XANES). The measured Cr redox ratio of the olivine phenocrysts can be readily converted to the ratio present in the conjugate melt via the ratio of crystal-liquid partition coefficients for Cr3+ and Cr2+. We have applied these results to modeling Cr spinel stability and Cr redox ratios in a primitive, iron-rich martian basalt.

  6. Oxidation of tertiary amines by cytochrome p450-kinetic isotope effect as a spin-state reactivity probe.

    Science.gov (United States)

    Li, Chunsen; Wu, Wei; Cho, Kyung-Bin; Shaik, Sason

    2009-08-24

    Two types of tertiary amine oxidation processes, namely, N-dealkylation and N-oxygenation, by compound I (Cpd I) of cytochrome P450 are studied theoretically using hybrid DFT calculations. All the calculations show that both N-dealkylation and N-oxygenation of trimethylamine (TMA) proceed preferentially from the low-spin (LS) state of Cpd I. Indeed, the computed kinetic isotope effects (KIEs) for the rate-controlling hydrogen abstraction step of dealkylation show that only the KIE(LS) fits the experimental datum, whereas the corresponding value for the high-spin (HS) process is much higher. These results second those published before for N,N-dimethylaniline (DMA), and as such, they further confirm the conclusion drawn then that KIEs can be a sensitive probe of spin state reactivity. The ferric-carbinolamine of TMA decomposes most likely in a non-enzymatic reaction since the Fe-O bond dissociation energy (BDE) is negative. The computational results reveal that in the reverse reaction of N-oxygenation, the N-oxide of aromatic amine can serve as a better oxygen donor than that of aliphatic amine to generate Cpd I. This capability of the N-oxo derivatives of aromatic amines to transfer oxygen to the heme, and thereby generate Cpd I, is in good accord with experimental data previously reported.

  7. Identification of the iron oxidation state and coordination geometry in iron oxide- and zeolite-based catalysts using pre-edge XAS analysis.

    Science.gov (United States)

    Boubnov, Alexey; Lichtenberg, Henning; Mangold, Stefan; Grunwaldt, Jan Dierk

    2015-03-01

    Analysis of the oxidation state and coordination geometry using pre-edge analysis is attractive for heterogeneous catalysis and materials science, especially for in situ and time-resolved studies or highly diluted systems. In the present study, focus is laid on iron-based catalysts. First a systematic investigation of the pre-edge region of the Fe K-edge using staurolite, FePO4, FeO and α-Fe2O3 as reference compounds for tetrahedral Fe(2+), tetrahedral Fe(3+), octahedral Fe(2+) and octahedral Fe(3+), respectively, is reported. In particular, high-resolution and conventional X-ray absorption spectra are compared, considering that in heterogeneous catalysis and material science a compromise between high-quality spectroscopic data acquisition and simultaneous analysis of functional properties is required. Results, which were obtained from reference spectra acquired with different resolution and quality, demonstrate that this analysis is also applicable to conventionally recorded pre-edge data. For this purpose, subtraction of the edge onset is preferentially carried out using an arctangent and a first-degree polynomial, independent of the resolution and quality of the data. For both standard and high-resolution data, multiplet analysis of pre-edge features has limitations due to weak transitions that cannot be identified. On the other hand, an arbitrary empirical peak fitting assists the analysis in that non-local transitions can be isolated. The analysis of the oxidation state and coordination geometry of the Fe sites using a variogram-based method is shown to be effective for standard-resolution data and leads to the same results as for high-resolution spectra. This method, validated by analysing spectra of reference compounds and their well defined mixtures, is finally applied to track structural changes in a 1% Fe/Al2O3 and a 0.5% Fe/BEA zeolite catalyst during reduction in 5% H2/He. The results, hardly accessible by other techniques, show that Fe(3+) is

  8. Identification of different oxygen species in oxide nanostructures with 17O solid-state NMR spectroscopy

    Science.gov (United States)

    Wang, Meng; Wu, Xin-Ping; Zheng, Sujuan; Zhao, Li; Li, Lei; Shen, Li; Gao, Yuxian; Xue, Nianhua; Guo, Xuefeng; Huang, Weixin; Gan, Zhehong; Blanc, Frédéric; Yu, Zhiwu; Ke, Xiaokang; Ding, Weiping; Gong, Xue-Qing; Grey, Clare P.; Peng, Luming

    2015-01-01

    Nanostructured oxides find multiple uses in a diverse range of applications including catalysis, energy storage, and environmental management, their higher surface areas, and, in some cases, electronic properties resulting in different physical properties from their bulk counterparts. Developing structure-property relations for these materials requires a determination of surface and subsurface structure. Although microscopy plays a critical role owing to the fact that the volumes sampled by such techniques may not be representative of the whole sample, complementary characterization methods are urgently required. We develop a simple nuclear magnetic resonance (NMR) strategy to detect the first few layers of a nanomaterial, demonstrating the approach with technologically relevant ceria nanoparticles. We show that the 17O resonances arising from the first to third surface layer oxygen ions, hydroxyl sites, and oxygen species near vacancies can be distinguished from the oxygen ions in the bulk, with higher-frequency 17O chemical shifts being observed for the lower coordinated surface sites. H217O can be used to selectively enrich surface sites, allowing only these particular active sites to be monitored in a chemical process. 17O NMR spectra of thermally treated nanosized ceria clearly show how different oxygen species interconvert at elevated temperature. Density functional theory calculations confirm the assignments and reveal a strong dependence of chemical shift on the nature of the surface. These results open up new strategies for characterizing nanostructured oxides and their applications. PMID:26601133

  9. Influence of de-hulled rapeseed roasting on the physicochemical composition and oxidative state of oil

    International Nuclear Information System (INIS)

    Rękas, A.; Siger, A.; Wroniak, M.; Ścibisz, I.; Derewiaka, D.; Anders, A.

    2017-01-01

    The effect of roasting time on the contents of bioactive compounds (tocopherols, phytosterols, phenolic compounds), antioxidant capacity and physicochemical properties of rapeseed oil pressed from de-hulled seeds was investigated. The de-hulled seeds were roasted at a temperature of 165 °C for 20, 40, 60, 80, and 100 min. The results of this study show that a roasting pre-treatment led to a gradual increase in canolol content (from 1.34 to 117.33 mg/100 g), total phytosterols (from 573.51 to 609.86 mg/100 g) and total carotenoids (0.82 to 2.41 mg/100 g), while only slight changes in the contents of tocopherols were noted. With the increase in roasting time a gradual increase in oxidative stability (from 4.27 to 6.85 h), and antioxidant capacity, seen mainly in the hydrophilic fraction of oil (from 0.32 to 2.30 mmol TEAC/l) was found. Although roasting resulted in the formation of primary and secondary oxidation products, the quality parameters of oils were within Codex Alimentarius limits. [es

  10. Elevated oxidative stress monitored via the albumin-thiol redox state is correlated with matrix metalloproteinase-3 elevation in patients with rheumatoid arthritis.

    Science.gov (United States)

    Kizaki, Kazuha; Yoshizumi, Yusuke; Takahashi, Teppei; Era, Seiichi

    2015-01-01

    In rheumatoid arthritis (RA), matrix metalloproteinase-3 (MMP-3) and oxidative stress contribute to joint destruction. However, little is known about the relationship between MMP-3 and oxidative stress in RA. We measured the albumin-thiol redox state as a marker of oxidative stress, MMP-3, and the DAS-28 score calculated using CRP values among forty-seven patients (9 males and 38 females) with RA. According to the serum MMP-3 levels, they were divided into two groups (group A: within normal ranges of 36.9-121.0 ng/mL for men and 17.3-59.7 ng/mL for women; group B: above normal ranges). The albumin-thiol redox state in group B was significantly oxidized compared with that in group A (p < 0.01). The percentage of oxidized albumin-thiol showed a positive correlation with serum MMP-3 (r = 0.52). DAS-28 and CRP were also correlated with the percentage of oxidized albumin-thiol (r = 0.46, r = 0.44). The albumin-thiol redox state was significantly oxidized in correlation with serum MMP-3 elevation in RA.

  11. Spiral spin state in high-temperature copper-oxide superconductors: Evidence from neutron scattering measurements

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    2005-01-01

    An effective spiral spin phase ground state provides a new paradigm for the high-temperature superconducting cuprates. It accounts for the recent neutron scattering observations of spin excitations regarding both the energy dispersion and the intensities, including the "universal" rotation by 45...... model. The form of the exchange interaction function reveals the effects of the Fermi surface, and the unique shape predicts large quantum spin fluctuations in the ground state....

  12. Correlation of the oxidation state of cerium in sol-gel glasses as a function of thermal treatment via optical spectroscopy and XANES studies.

    Science.gov (United States)

    Assefa, Zerihun; Haire, R G; Caulder, D L; Shuh, D K

    2004-07-01

    Sol-gel glass matrices containing lanthanides have numerous technological applications and their formation involves several chemical facets. In the case of cerium, its ability to exist in two different oxidation states or in mixed valence state provides additional complexities for the sol-gel process. The oxidation state of cerium present during different facets of preparation of sol-gel glasses, and also as a function of the starting oxidation state of cerium added, were studied both by optical spectroscopy and X-ray absorption near-edge structures (XANES). The findings acquired by each approach were compared. The primary focus was on the redox chemistries associated with sample preparation, gelation, and thermal treatment. When Ce3+ is introduced into the starting sols, the trivalent state normally prevails in the wet and room temperature-dried gels. Heating in air at >100 degrees C can generate a light yellow coloration with partial oxidation to the tetravalent state. Above 200 degrees C and up to approximately 1000 degrees C, cerium is oxidized to its tetravalent state. In contrast, when tetravalent cerium is introduced into the sol, both the wet and room temperature-dried gels lose the yellow-brown color of the initial ceric ammonium nitrate solution. When the sol-gel is heated to 110 degrees C it turns yellowish as the cerium tends to be re-oxidized. The yellow color is believed to represent the effect of oxidation and oligomerization of the cerium-silanol units in the matrix. The luminescence properties are also affected by these changes, the details of which are reported herein.

  13. In-situ preparation of poly(ethylene oxide)/Li3PS4 hybrid polymer electrolyte with good nanofiller distribution for rechargeable solid-state lithium batteries

    Science.gov (United States)

    Chen, Shaojie; Wang, Junye; Zhang, Zhihua; Wu, Linbin; Yao, Lili; Wei, Zhenyao; Deng, Yonghong; Xie, Dongjiu; Yao, Xiayin; Xu, Xiaoxiong

    2018-05-01

    Nano-sized fillers in a polymer matrix with good distribution can play a positive role in improving polymer electrolytes in the aspects of ionic conductivity, mechanical property and electrochemical performance of Li-ion cells. Herein, polyethylene oxide (PEO)/Li3PS4 hybrid polymer electrolyte is prepared via a new in-situ approach. The ionic conductivities of the novel hybrid electrolytes with variable proportions are measured, and the optimal electrolyte of PEO-2%vol Li3PS4 presents a considerable ionic conductivity of 8.01 × 10-4 S cm-1 at 60 °C and an electrochemical window up to 5.1 V. The tests of DSC and EDXS reveal that the Li3PS4 nanoparticles with better distribution, as active fillers scattering in the PEO, exhibit a positive effect on the transference of lithium ion and electrochemical interfacial stabilities. Finally, the assembled solid-state LiFePO4/Li battery presents a decent cycling performance (80.9% retention rate after 325 cycles at 60 °C) and excellent rate capacities with 153, 143, 139 and 127 mAh g-1 at the discharging rate of 0.1 C, 0.2 C, 0.5 C and 1 C at 60 °C. It is fully proved that it is an advanced strategy to preparing the new organic/inorganic hybrid electrolytes for lithium-ion batteries applications.

  14. Electrochemical determination of the oxidation potentials and the thermodynamic stability of the valence states of the transuranium elements in aqueous alkaline media

    International Nuclear Information System (INIS)

    Peretrukhin, V.F.; Spitsyn, V.I.

    1982-01-01

    The oxidation potentials of neptunium, plutonium, and americium in the valance states from (III) to (VII) have been determined experimentally in 0.1-15 M NaOH. Heptavalent plutonium and americium are thermodynamically able to oxidize water with the evolution of oxygen in 0.1-15 M NaOH, neptunium(VII) in 0.1-7 M NaOH. All valance states of plutonium resist disproportionation in alkaline solutions; in the case of neptunium and americium only one disproportionation reaction is possible; of the hexavalent state in to penta- and heptavalent states. The degree of completion of the reaction can be calculated accurately from the oxidation potentials determined

  15. Autophagy and oxidative stress in non-communicable diseases: A matter of the inflammatory state?

    Science.gov (United States)

    Peña-Oyarzun, Daniel; Bravo-Sagua, Roberto; Diaz-Vega, Alexis; Aleman, Larissa; Chiong, Mario; Garcia, Lorena; Bambs, Claudia; Troncoso, Rodrigo; Cifuentes, Mariana; Morselli, Eugenia; Ferreccio, Catterina; Quest, Andrew F G; Criollo, Alfredo; Lavandero, Sergio

    2018-05-30

    Non-communicable diseases (NCDs), also known as chronic diseases, are long-lasting conditions that affect millions of people around the world. Different factors contribute to their genesis and progression; however they share common features, which are critical for the development of novel therapeutic strategies. A persistently altered inflammatory response is typically observed in many NCDs together with redox imbalance. Additionally, dysregulated proteostasis, mainly derived as a consequence of compromised autophagy, is a common feature of several chronic diseases. In this review, we discuss the crosstalk among inflammation, autophagy and oxidative stress, and how they participate in the progression of chronic diseases such as cancer, cardiovascular diseases, obesity and type II diabetes mellitus. Copyright © 2018 Elsevier Inc. All rights reserved.

  16. Brain oxidative metabolism of the newborn dog: correlation between 31P NMR spectroscopy and pyridine nucleotide redox state.

    Science.gov (United States)

    Mayevsky, A; Nioka, S; Subramanian, V H; Chance, B

    1988-04-01

    The effects of both anoxia and short- and long-term hypoxia on brain oxidative metabolism were studied in newborn dogs. Oxidative metabolism was evaluated by two independent measures: in vivo continuous monitoring of mitochondrial NADH redox state and energy stores as calculated from the phosphocreatine (PCr)/Pi levels measured by 31P nuclear magnetic resonance (NMR) spectroscopy. The hemodynamic response to low oxygen supply was further evaluated by measuring the changes in the reflected light intensity at 366 nm (the excitation wavelength for NADH). The animal underwent surgery and was prepared for monitoring of the two signals (NADH and PCr/Pi). It was then placed inside a Phosphoenergetics 260-80 NMR spectrometer magnet with a 31-cm bore. Each animal (1-21 days old) was exposed to short-term anoxia or hypoxia as well as to long-term hypoxia (1-2 h). The results can be summarized as follow: (a) In the normoxic brain, the ratio between PCr and Pi was greater than 1 (1.2-1.4), while under hypoxia or asphyxia a significant decrease that was correlated to the FiO2 levels was recorded. (b) A clear correlation was found between the decrease in PCr/Pi values and the increased NADH redox state developed under decreased O2 supply to the brain. (c) Exposing the animal to moderately long-term hypoxia led to a stabilized low-energy state of the brain with a good recovery after rebreathing normal air. (d) Under long-term and severe hypoxia, the microcirculatory autoregulatory mechanism was damaged and massive vasoconstriction was optically recorded simultaneously with a significant decrease in PCr/Pi values.(ABSTRACT TRUNCATED AT 250 WORDS)

  17. Decadal changes in summertime reactive oxidized nitrogen and surface ozone over the Southeast United States

    Science.gov (United States)

    Li, Jingyi; Mao, Jingqiu; Fiore, Arlene M.; Cohen, Ronald C.; Crounse, John D.; Teng, Alex P.; Wennberg, Paul O.; Lee, Ben H.; Lopez-Hilfiker, Felipe D.; Thornton, Joel A.; Peischl, Jeff; Pollack, Ilana B.; Ryerson, Thomas B.; Veres, Patrick; Roberts, James M.; Neuman, J. Andrew; Nowak, John B.; Wolfe, Glenn M.; Hanisco, Thomas F.; Fried, Alan; Singh, Hanwant B.; Dibb, Jack; Paulot, Fabien; Horowitz, Larry W.

    2018-02-01

    Widespread efforts to abate ozone (O3) smog have significantly reduced emissions of nitrogen oxides (NOx) over the past 2 decades in the Southeast US, a place heavily influenced by both anthropogenic and biogenic emissions. How reactive nitrogen speciation responds to the reduction in NOx emissions in this region remains to be elucidated. Here we exploit aircraft measurements from ICARTT (July-August 2004), SENEX (June-July 2013), and SEAC4RS (August-September 2013) and long-term ground measurement networks alongside a global chemistry-climate model to examine decadal changes in summertime reactive oxidized nitrogen (RON) and ozone over the Southeast US. We show that our model can reproduce the mean vertical profiles of major RON species and the total (NOy) in both 2004 and 2013. Among the major RON species, nitric acid (HNO3) is dominant (˜ 42-45 %), followed by NOx (31 %), total peroxy nitrates (ΣPNs; 14 %), and total alkyl nitrates (ΣANs; 9-12 %) on a regional scale. We find that most RON species, including NOx, ΣPNs, and HNO3, decline proportionally with decreasing NOx emissions in this region, leading to a similar decline in NOy. This linear response might be in part due to the nearly constant summertime supply of biogenic VOC emissions in this region. Our model captures the observed relative change in RON and surface ozone from 2004 to 2013. Model sensitivity tests indicate that further reductions of NOx emissions will lead to a continued decline in surface ozone and less frequent high-ozone events.

  18. Decadal changes in summertime reactive oxidized nitrogen and surface ozone over the Southeast United States

    Directory of Open Access Journals (Sweden)

    J. Li

    2018-02-01

    Full Text Available Widespread efforts to abate ozone (O3 smog have significantly reduced emissions of nitrogen oxides (NOx over the past 2 decades in the Southeast US, a place heavily influenced by both anthropogenic and biogenic emissions. How reactive nitrogen speciation responds to the reduction in NOx emissions in this region remains to be elucidated. Here we exploit aircraft measurements from ICARTT (July–August 2004, SENEX (June–July 2013, and SEAC4RS (August–September 2013 and long-term ground measurement networks alongside a global chemistry–climate model to examine decadal changes in summertime reactive oxidized nitrogen (RON and ozone over the Southeast US. We show that our model can reproduce the mean vertical profiles of major RON species and the total (NOy in both 2004 and 2013. Among the major RON species, nitric acid (HNO3 is dominant (∼ 42–45 %, followed by NOx (31 %, total peroxy nitrates (ΣPNs; 14 %, and total alkyl nitrates (ΣANs; 9–12 % on a regional scale. We find that most RON species, including NOx, ΣPNs, and HNO3, decline proportionally with decreasing NOx emissions in this region, leading to a similar decline in NOy. This linear response might be in part due to the nearly constant summertime supply of biogenic VOC emissions in this region. Our model captures the observed relative change in RON and surface ozone from 2004 to 2013. Model sensitivity tests indicate that further reductions of NOx emissions will lead to a continued decline in surface ozone and less frequent high-ozone events.

  19. Air oxidation of Zr65Cu17.5Ni10Al7.5 in its amorphous and supercooled liquid states, studied by thermogravimetric analysis

    International Nuclear Information System (INIS)

    Dhawan, A.; Sharma, S.K.; Raetzke, K.; Faupel, F.

    2003-01-01

    The oxidation behaviour of the bulk amorphous alloy Zr 65 Cu 17.5 Ni 10 Al 7.5 was studied in air at various temperatures in the temperature range 591-732 K using a thermogravimetric analyser (TGA). The oxidation kinetics of the alloy obeys the parabolic rate law showing two different linear regions (in the plots of mass gain versus square root of oxidation time) which are attributed to the amorphous and the supercooled liquid states of the alloy. The value of the activation energy Q for the amorphous state as calculated from the temperature dependence of the rate constants is found to be 1.80±0.1 eV and the corresponding value obtained for the supercooled liquid state is 1.20±0.1 eV. It is suggested that the rate controlling process during oxidation of the amorphous state is the back-diffusion of Ni, and possibly Cu also, while the oxidation in the supercooled liquid state is dominated by the inward diffusion of oxygen. (copyright 2003 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Speciation of the oxidation states of plutonium in aqueous solutions by UV/Vis spectroscopy, CE-ICP-MS and CE-RIMS

    International Nuclear Information System (INIS)

    Buerger, S.; Banik, N.L.; Buda, R.A.; Kratz, J.V.; Kuczewski, B.; Trautmann, N.

    2007-01-01

    For the speciation of the plutonium oxidation states in aqueous solutions, the online coupling of capillary electrophoresis (CE) with inductively coupled plasma mass spectrometry (ICP-MS) has been developed. Depending on the radius/electrical charge ratio, the oxidation states III, IV, V, and VI of plutonium are separated by CE, based on the different migration times through the capillary and are detected by ICP-MS. The detection limit is 20 ppb, i.e. 10 9 -10 10 atoms (10 -12 -10 -13 g) for one oxidation state with an uncertainty of the reproducibility of the migration times of ≤ 1% and ≤ 5% for the peak area. The redox kinetics of the different plutonium oxidation states in the presence of humic substances (humic and fulvic acid) have been studied. A relatively rapid reduction of Pu(VI) (10 to 1000 h) in contact with Gorleben fulvic or Aldrich humic acid could be observed, depending on the pH of the solution. Furthermore, at pH=1, a reduction to Pu(III) and Pu(IV) in a mixture of all four oxidation states in contact with Gorleben fulvic acid after one month has been observed. In order to improve the sensitivity of the CE method, the offline coupling of CE to resonance ionization mass spectrometry (RIMS) has been explored. First applications of this new speciation method are presented. (orig.)

  1. Tin Oxide Nanowires: The Influence of Trap States on Ultrafast Carrier Relaxation

    Directory of Open Access Journals (Sweden)

    Zervos Matthew

    2009-01-01

    Full Text Available Abstract We have studied the optical properties and carrier dynamics in SnO2nanowires (NWs with an average radius of 50 nm that were grown via the vapor–liquid solid method. Transient differential absorption measurements have been employed to investigate the ultrafast relaxation dynamics of photogenerated carriers in the SnO2NWs. Steady state transmission measurements revealed that the band gap of these NWs is 3.77 eV and contains two broad absorption bands. The first is located below the band edge (shallow traps and the second near the center of the band gap (deep traps. Both of these absorption bands seem to play a crucial role in the relaxation of the photogenerated carriers. Time resolved measurements suggest that the photogenerated carriers take a few picoseconds to move into the shallow trap states whereas they take ~70 ps to move from the shallow to the deep trap states. Furthermore the recombination process of electrons in these trap states with holes in the valence band takes ~2 ns. Auger recombination appears to be important at the highest fluence used in this study (500 μJ/cm2; however, it has negligible effect for fluences below 50 μJ/cm2. The Auger coefficient for the SnO2NWs was estimated to be 7.5 ± 2.5 × 10−31 cm6/s.

  2. SURFACE AND LIGHTNING SOURCES OF NITROGEN OXIDES OVER THE UNITED STATES: MAGNITUDES, CHEMICAL EVOLUTION, AND OUTFLOW

    Science.gov (United States)

    We use observations from two aircraft during the ICARTT campaign over the eastern United States and North Atlantic during summer 2004, interpreted with a global 3-D model of tropospheric chemistry (GEOS-Chem) to test current understanding of regional sources, chemical evolution...

  3. Nanoscale probing of bandgap states on oxide particles using electron energy-loss spectroscopy.

    Science.gov (United States)

    Liu, Qianlang; March, Katia; Crozier, Peter A

    2017-07-01

    Surface and near-surface electronic states were probed with nanometer spatial resolution in MgO and TiO 2 anatase nanoparticles using ultra-high energy resolution electron energy-loss spectroscopy (EELS) coupled to a scanning transmission electron microscope (STEM). This combination allows the surface electronic structure determined with spectroscopy to be correlated with nanoparticle size, morphology, facet etc. By acquiring the spectra in aloof beam mode, radiation damage to the surface can be significantly reduced while maintaining the nanometer spatial resolution. MgO and TiO 2 showed very different bandgap features associated with the surface/sub-surface layer of the nanoparticles. Spectral simulations based on dielectric theory and density of states models showed that a plateau feature found in the pre-bandgap region in the spectra from (100) surfaces of 60nm MgO nanocubes is consistent with a thin hydroxide surface layer. The spectroscopy shows that this hydroxide species gives rise to a broad filled surface state at 1.1eV above the MgO valence band. At the surfaces of TiO 2 nanoparticles, pronounced peaks were observed in the bandgap region, which could not be well fitted to defect states. In this case, the high refractive index and large particle size may make Cherenkov or guided light modes the likely causes of the peaks. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Effect of additions of cerium, lanthanum, and zirconium on the state of plantinum and the activity of aluminoplatinum catalysts for the complete oxidation of hydrocarbons

    International Nuclear Information System (INIS)

    Drozdov, V.A.; Davydov, A.A.; Popovskii, V.V.; Tsyrul'nikov, P.G.

    1986-01-01

    It is shown from an analysis of the diffuse reflectance spectra that additions of cerium, lanthanum or zirconium to aluminoplatinum catalyst stabilize the platinum in an oxidized state. This leads to a change in the specific catalytic activity (SCA) towards the total oxidation of methane and butane. The SCA of modified, reduced samples is greater than the SCA of samples that were calcined in air. This is because of the greater activity of metallic platinum compared to the ionic form

  5. Mn K-edge XANES spectroscopy of photosynthetic water oxidation enzyme in the S0-, S1-, S2- and S3-states induced by flash excitation

    International Nuclear Information System (INIS)

    Ono, Taka-aki; Noguchi, Takumi; Inoue, Yorinao; Kusunoki, Masami; Matsushita, Tadashi; Oyanagi, Hiroyuki.

    1993-01-01

    Electronic and structural rearrangement of the Mn-cluster during the four step oxidation of water in photosynthetic oxygen evolution was studied by XANES spectroscopy. The Mn K-edge energy of the spectrum was changed with flash number to show a clear quadruple oscillation, indicating a periodic change in oxidation and electronic state of the Mn-cluster depending on Joliot and Kok's oxygen clock. (author)

  6. Electroencephalogram, cognitive state, psychological disorders, clinical symptom, and oxidative stress in horticulture farmers exposed to organophosphate pesticides.

    Science.gov (United States)

    Bayrami, Mansour; Hashemi, Touraj; Malekirad, Ali Akbar; Ashayeri, Hassan; Faraji, Fardin; Abdollahi, Mohammad

    2012-02-01

    The aim of this paper was to study the toxicity of organophosphate (OP) pesticides in exposed farmers for electroencephalography, cognitive state, psychological disorders, clinical symptom, oxidative stress, acetylcholinesterase, and DNA damage. A comparative cross-sectional analysis was carried out in 40 horticulture farmers who were exposed to OPs in comparison to a control group containing 40 healthy subjects with the same age and sex and education level. Lipid peroxidation (LPO), superoxide dismutase (SOD), catalase, glutathione peroxidase, DNA damage, total antioxidant capacity (TAC), total thiol molecules, and acetylcholinesterase (AChE) activity were measured in the blood of subjects. Clinical examination and complete blood test were undertaken in order to record any abnormal sign or symptoms. Cognitive function, psychological symptoms, and psychological distress were examined and recorded. Comparing with controls, the farmers showed higher blood levels of SOD and LPO while their TAC decreased. Farmers showed clinical symptoms such as eczema, breathing muscle weakness, nausea, and saliva secretion. Regarding cognitive function, the orientation, registration, attention and calculation, recall, and language were not significantly different in farmers and controls. Among examinations for psychological distress, only labeled somatization was significantly higher in farmers. The present findings indicate that oxidative stress and inhibition of AChE can be seen in chronically OP-exposed people but incidence of neuropsychological disorders seems a complex multivariate phenomenon that might be seen in long-term high-dose exposure situations. Use of supplementary antioxidants would be useful in the treatment of farmers.

  7. Steady-state oxidation of cholesterol catalyzed by cholesterol oxidase in lipid bilayer membranes on platinum electrodes

    International Nuclear Information System (INIS)

    Bokoch, Michael P.; Devadoss, Anando; Palencsar, Mariela S.; Burgess, James D.

    2004-01-01

    Cholesterol oxidase is immobilized in electrode-supported lipid bilayer membranes. Platinum electrodes are initially modified with a self-assembled monolayer of thiolipid. A vesicle fusion method is used to deposit an outer leaflet of phospholipids onto the thiolipid monolayer forming a thiolipid/lipid bilayer membrane on the electrode surface. Cholesterol oxidase spontaneously inserts into the electrode-supported lipid bilayer membrane from solution and is consequently immobilized to the electrode surface. Cholesterol partitions into the membrane from buffer solutions containing cyclodextrin. Cholesterol oxidase catalyzes the oxidation of cholesterol by molecular oxygen, forming hydrogen peroxide as a product. Amperometric detection of hydrogen peroxide for continuous solution flow experiments are presented, where flow was alternated between cholesterol solution and buffer containing no cholesterol. Steady-state anodic currents were observed during exposures of cholesterol solutions ranging in concentration from 10 to 1000 μM. These data are consistent with the Michaelis-Menten kinetic model for oxidation of cholesterol as catalyzed by cholesterol oxidase immobilized in the lipid bilayer membrane. The cholesterol detection limit is below 1 μM for cholesterol solution prepared in buffered cyclodextrin. The response of the electrodes to low density lipoprotein solutions is increased upon addition of cyclodextrin. Evidence for adsorption of low density lipoprotein to the electrode surface is presented

  8. Nickel Oxide (NiO nanoparticles prepared by solid-state thermal decomposition of Nickel (II schiff base precursor

    Directory of Open Access Journals (Sweden)

    Aliakbar Dehno Khalaji

    2015-06-01

    Full Text Available In this paper, plate-like NiO nanoparticles were prepared by one-pot solid-state thermal decomposition of nickel (II Schiff base complex as new precursor. First, the nickel (II Schiff base precursor was prepared by solid-state grinding using nickel (II nitrate hexahydrate, Ni(NO32∙6H2O, and the Schiff base ligand N,N′-bis-(salicylidene benzene-1,4-diamine for 30 min without using any solvent, catalyst, template or surfactant. It was characterized by Fourier Transform Infrared spectroscopy (FT-IR and elemental analysis (CHN. The resultant solid was subsequently annealed in the electrical furnace at 450 °C for 3 h in air atmosphere. Nanoparticles of NiO were produced and characterized by X-ray powder diffraction (XRD at 2θ degree 0-140°, FT-IR spectroscopy, scanning electron microscopy (SEM and transmission electron microscopy (TEM. The XRD and FT-IR results showed that the product is pure and has good crystallinity with cubic structure because no characteristic peaks of impurity were observed, while the SEM and TEM results showed that the obtained product is tiny, aggregated with plate-like shape, narrow size distribution with an average size between 10-40 nm. Results show that the solid state thermal decomposition method is simple, environmentally friendly, safe and suitable for preparation of NiO nanoparticles. This method can also be used to synthesize nanoparticles of other metal oxides.

  9. Diversity of Chemical Bonding and Oxidation States in MS 4 Molecules of Group 8 Elements

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Wei [Department of Chemistry and Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Tsinghua University, Beijing 100084 P.R. China; Jiang, Ning [Department of Chemistry and Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Tsinghua University, Beijing 100084 P.R. China; Schwarz, W. H. Eugen [Department of Chemistry and Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Tsinghua University, Beijing 100084 P.R. China; Physical and Theoretical Chemistry, University of Siegen, Siegen 57068 Germany; Yang, Ping [Theoretical Division, Los Alamos National Laboratory, Los Alamos New Mexico 87545 USA; Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, Richland Washington 953002 USA; Li, Jun [Department of Chemistry and Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Tsinghua University, Beijing 100084 P.R. China; Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, Richland Washington 953002 USA

    2017-07-11

    The geometric and electronic ground-state structures of six MS4 molecules (M = group-8 metals Fe, Ru, Os, Hs, Sm, and Pu) have been studied by using quantum-chemical density-functional and correlated wave-function approaches. The MS4 species are compared to analogous MO4 species recently investi-gated (Inorg. Chem. 2016, 55: 4616). Metal oxidation state (MOS) of high value VIII appears in low- spin singlet Td geometric species (Os,Hs)S4 and (Ru,Os,Hs)O4, whereas low MOS=II appears in high- spin septet D2d species Fe(S2)2 and (slightly excited) metastable Fe(O2)2. The ground states of all other molecules have intermediate MOS values, containing S2-, S22-, S21- (and resp. O2--, O1-, O22-, O21-) ligands, bonded by ionic, covalent and correlative contributions.

  10. A Singular Perturbation Problem for Steady State Conversion of Methane Oxidation in Reverse Flow Reactor

    Directory of Open Access Journals (Sweden)

    Aang Nuryaman

    2012-11-01

    Full Text Available The governing equations describing the methane oxidation process in reverse flow reactor are given by a set of convective-diffusion equations with a nonlinear reaction term, where temperature and methane conversion are dependent variables. In this study, the process is assumed to be one-dimensional pseudo homogeneous model and takes place with a certain reaction rate in which the whole process of reactor is still workable. Thus, the reaction rate can proceed at a fixed temperature. Under this condition, we restrict ourselves to solve the equations for the conversion only. From the available data, it turns out that the ratio of the diffusion term to the reaction term is small. Hence, this ratio is considered as small parameter in our model and this leads to a singular perturbation problem. In the vicinity of small parameter in front of higher order term, the numerical difficulties will be found. Here, we present an analytical solution by means of matched asymptotic expansions. Result shows that, up to and including the first order of approximation, the solution is in agreement with the exact and numerical solutions of the boundary value problem.

  11. Simulation of the steady-state behaviour of a new design of a single planar Solid Oxide Fuel Cell

    Directory of Open Access Journals (Sweden)

    Pianko-Oprych Paulina

    2016-03-01

    Full Text Available The aim of the work was to develop a mathematical model for computing the steady-state voltage – current characteristics of a planar Solid Oxide Fuel Cell and to determine the performance of a new SOFC design. The design involves cross-flow bipolar plates. Each of the bipolar plates has an air channel system on one side and a fuel channel system on the other side. The proposed model was developed using the ANSYS-Fluent commercial Computational Fluid Dynamics (CFD software supported by additional Fuel Cell module. The results confirm that the model can well simulate the diagonal current path. The effects of temperature and gas flow through the channels and a Membrane Electrode Assembly (MEA structure were taken into account. It was shown that a significant increase of the MEA temperature at high current density can lead to hot spots formation and hence electrode damage.

  12. All-solid-state flexible supercapacitors based on highly dispersed polypyrrole nanowire and reduced graphene oxide composites.

    Science.gov (United States)

    Yu, Chenfei; Ma, Peipei; Zhou, Xi; Wang, Anqi; Qian, Tao; Wu, Shishan; Chen, Qiang

    2014-10-22

    Highly dispersed polypyrrole nanowires are decorated on reduced graphene oxide sheets using a facile in situ synthesis route. The prepared composites exhibit high dispersibility, large effective surface area, and high electric conductivity. All-solid-state flexible supercapacitors are assembled based on the prepared composites, which show excellent electrochemical performances with a specific capacitance of 434.7 F g(-1) at a current density of 1 A g(-1). The as-fabricated supercapacitor also exhibits excellent cycling stability (88.1% capacitance retention after 5000 cycles) and exceptional mechanical flexibility. In addition, outstanding power and energy densities were obtained, demonstrating the significant potential of prepared material for flexible and portable energy storage devices.

  13. Eco-friendly wood-based solid-state flexible supercapacitors from wood transverse section slice and reduced graphene oxide

    Science.gov (United States)

    Lv, Shaoyi; Fu, Feng; Wang, Siqun; Huang, Jingda; Hu, La

    2015-07-01

    An interesting wood-based all-solid-state supercapacitor is produced using reduced graphene oxide (RGO) coated on wood transverse section slice (WTSS) as electrode material by means of a low-cost, eco-friendly, and simple method for the first time. The RGO-coated WTSS electrode has a porous 3D honeycomb framework due to the hierarchical cellular structure of the WTSS substrate and can function as an electrolyte reservoir. This special construction endows this novel electrode with good areal capacitance (102 mF cm-2) and excellent cyclic stability (capacitance retention of 98.9% after 5000 cycles). In addition, the supercapacitors exhibit good mechanical flexibility and preserve almost constant capacitive behavior under different bending conditions. Our study introduces a new and eco-friendly material design for electrodes in future flexible energy storage devices that closely resemble natural materials. [Figure not available: see fulltext.

  14. Synthesis and Electrochemistry of Li3MnO4: Mn in the +5 OxidationState

    Energy Technology Data Exchange (ETDEWEB)

    Saint, Juliette.A.; Doeff, Marca M.; Reed, John

    2007-06-19

    Computational and experimental work directed at exploringthe electrochemical properties of tetrahedrally coordinated Mn in the +5oxidation state is presented. Specific capacities of nearly 700 mAh/g arepredicted for the redox processes of LixMnO4 complexes based on twotwo-phase reactions. One is topotactic extractionof Li from Li3MnO4 toform LiMnO4 and the second is topotactic insertion of Li into Li3MnO4 toform Li5MnO4. In experiments, it is found that the redox behavior ofLi3MnO4 is complicated by disproportionation of Mn5+ in solution to formMn4+ and Mn7+ and byother irreversible processes; although an initialcapacity of about 275 mAh/g in lithiumcells was achieved. Strategiesbased on structural considerations to improve the electrochemicalproperties of MnO4n- complexes are given.

  15. Influence of Battery Parametric Uncertainties on the State-of-Charge Estimation of Lithium Titanate Oxide-Based Batteries

    DEFF Research Database (Denmark)

    Stroe, Ana-Irina; Meng, Jinhao; Stroe, Daniel-Ioan

    2018-01-01

    to describe the battery dynamics. The SOC estimation method proposed in this paper is based on an Extended Kalman Filter (EKF) and nonlinear battery model which was parameterized using extended laboratory tests performed on several 13 Ah lithium titanate oxide (LTO)-based lithium-ion batteries. The developed......State of charge (SOC) is one of the most important parameters in battery management systems, as it indicates the available battery capacity at every moment. There are numerous battery model-based methods used for SOC estimation, the accuracy of which depends on the accuracy of the model considered...... a sensitivity analysis it was showed that the SOC and voltage estimation error are only slightly dependent on the variation of the battery model parameters with the SOC....

  16. Interval training in the fed or fasted state improves body composition and muscle oxidative capacity in overweight women.

    Science.gov (United States)

    Gillen, Jenna B; Percival, Michael E; Ludzki, Alison; Tarnopolsky, Mark A; Gibala, Martin J

    2013-11-01

    To investigate the effects of low-volume high-intensity interval training (HIT) performed in the fasted (FAST) versus fed (FED) state on body composition, muscle oxidative capacity, and glycemic control in overweight/obese women. Sixteen women (27 ± 8 years, BMI: 29 ± 6 kg/m(2) , VO2peak : 28 ± 3 ml/kg/min) were assigned to either FAST or FED (n = 8 each) and performed 18 sessions of HIT (10× 60-s cycling efforts at ∼90% maximal heart rate, 60-s recovery) over 6 weeks. There was no significant difference between FAST and FED for any measured variable. Body mass was unchanged following training; however, dual energy X-ray absorptiometry revealed lower percent fat in abdominal and leg regions as well as the whole body level (main effects for time, P ≤ 0.05). Fat-free mass increased in leg and gynoid regions (P ≤ 0.05). Resting muscle biopsies revealed a training-induced increase in mitochondrial capacity as evidenced by increased maximal activities of citrate synthase and β-hydroxyacyl-CoA dehydrogenase (P ≤ 0.05). There was no change in insulin sensitivity, although change in insulin area under the curve was correlated with change in abdominal percent fat (r = 0.54, P ≤ 0.05). Short-term low-volume HIT is a time-efficient strategy to improve body composition and muscle oxidative capacity in overweight/obese women, but fed- versus fasted-state training does not alter this response. Copyright © 2013 The Obesity Society.

  17. Magnetotransport investigations of the two-dimensional metallic state in silicon metal-oxid-semiconductor structures

    International Nuclear Information System (INIS)

    Prinz, A.

    2002-03-01

    For more than two decades it was the predominant view among the physical community that the every two-dimensional (2D) disordered electron system becomes insulating as the temperature approaches the absolute zero temperature (0 Kelvin or -273.15 o C). Two-dimensional means that the movement of the charge carriers is confined in one direction by a potential so that the carriers can move freely only perpendicular to the confinement. The most famous physical realization of a 2D system is the silicon metal-oxide-semiconductor field effect transistor (Si-MOSFET). It is one of the basic elements of most electronic devices in our daily life. The working principle is very simple. Charges are attracted to the semiconductor-oxide interface by an electric field applied between the metallic gate and the semiconductor, so that a 2D conductive channel is formed. The charge density can be adjusted by the voltage from zero up to 10 13 cm -2 . In 1994 Kravchenko and coworkers made a very important discovery. They studied high mobility Si-MOSFETs and found that for densities below a certain critical value, nc, the resistivity increases as the temperature is decreased below 2 K, whereas for densities above $n c $ the resistivity decreases unexpectedly. The transition from insulating to metallic behavior, known as metal-insulator transition (MIT), was obviously a contradiction to the commonly accepted theories which predict insulating behavior for any density. The insulating behavior is a consequence of the wave properties of electrons which leads to interference in disordered media and thus to enhanced backscattering. In the subsequent years, experimental studies were performed on a variety of 2D systems, which qualitatively showed a similar behavior. All the investigated samples had one thing in common. The interaction energy between the carriers was considerable higher than their mean kinetic energy due to their movement in the 2D plane. Since the electron-electron interaction was

  18. The oxidation state of Fe in MORB glasses and the oxygen fugacity of the upper mantle

    Science.gov (United States)

    Cottrell, Elizabeth; Kelley, Katherine A.

    2011-05-01

    Micro-analytical determination of Fe3+/∑Fe ratios in mid-ocean ridge basalt (MORB) glasses using micro X-ray absorption near edge structure (μ-XANES) spectroscopy reveals a substantially more oxidized upper mantle than determined by previous studies. Here, we show that global MORBs yield average Fe3+/∑Fe ratios of 0.16 ± 0.01 (n = 103), which trace back to primary MORB melts equilibrated at the conditions of the quartz-fayalite-magnetite (QFM) buffer. Our results necessitate an upward revision of the Fe3+/∑Fe ratios of MORBs, mantle oxygen fugacity, and the ferric iron content of the mantle relative to previous wet chemical determinations. We show that only 0.01 (absolute, or Co-variations of Fe3+/∑Fe ratios in global MORB with indices of low-pressure fractional crystallization are consistent with Fe3+ behaving incompatibly in shallow MORB magma chambers. MORB Fe3+/∑Fe ratios do not, however, vary with indices of the extent of mantle melting (e.g., Na2O(8)) or water concentration. We offer two hypotheses to explain these observations: The bulk partition coefficient of Fe3+ may be higher during peridotite melting than previously thought, and may vary with temperature, or redox exchange between sulfide and sulfate species could buffer mantle melting at ~ QFM. Both explanations, in combination with the measured MORB Fe3+/∑Fe ratios, point to a fertile MORB source with greater than 0.3 wt.% Fe2O3.

  19. Thermodynamic properties of ternary oxides in the system Ba-Fe-O using solid-state electrochemical cells with oxide and fluoride ion conducting electrolytes

    Science.gov (United States)

    Rakshit, S. K.; Parida, S. C.; Singh, Ziley; Prasad, R.; Venugopal, V.

    2004-04-01

    The standard molar Gibbs energy of formations of BaFe 12O 19(s), BaFe 2O 4(s), Ba 2Fe 2O 5(s), Ba 3Fe 2O 6(s) and Ba 5Fe 2O 8(s) have been determined using solid-state electrochemical technique employing CaF 2(s) as an electrolyte. The reversible e.m.f. values have been measured in the temperature range from 970 to 1151 K. The oxygen chemical potential corresponding to three phase equilibria involving technologically important compound BaFe 12O 19(s) has been determined using solid-state electrochemical technique employing CSZ as an electrolyte from 1048 to 1221 K. The values of Δ fGm0( T) for the above ternary oxides are given by ΔfG m0( BaFe12O19, s)/ kJ mol -1(±0.6)=-5431.3+1.5317 (T/ K) (970⩽T/ K⩽1151) ΔfG m0( BaFe2O4, s)/ kJ mol -1(±1.3)=-1461.4+0.3745 (T/ K) (970⩽T/ K⩽1151) ΔfG m0( Ba2Fe2O5, s)/ kJ mol -1(±1.4)=-2038.3+0.4433 (T/ K) (970⩽T/ K⩽1149) ΔfG m0( Ba3Fe2O6, s)/ kJ mol -1(±1.5)=-2700.1+0.6090 (T/ K) (969⩽T/ K⩽1150) and ΔfG m0( Ba5Fe2O8, s)/ kJ mol -1(±1.6)=-3984.1+0.9300 (T/ K) (973⩽T/ K⩽1150) The uncertainty estimates for Δ fGm0 includes the standard deviation in the e.m.f. and uncertainty in the data taken from the literature. An isothermal oxygen potential diagram for the system Ba-Fe-O was constructed at 1100 K based on the thermodynamic data obtained in this study.

  20. Transition Metal Oxides for the Oxygen Reduction Reaction: Influence of the Oxidation States of the Metal and its Position on the Periodic Table.

    Science.gov (United States)

    Toh, Rou Jun; Sofer, Zdeněk; Pumera, Martin

    2015-11-16

    Electrocatalysts have been developed to meet the needs and requirements of renewable energy applications. Metal oxides have been well explored and are promising for this purpose, however, many reports focus on only one or a few metal oxides at once. Herein, thirty metal oxides, which were either commercially available or synthesized by a simple and scalable method, were screened for comparison with regards to their electrocatalytic activity towards the oxygen reduction reaction (ORR). We show that although manganese, iron, cobalt, and nickel oxides generally displayed the ability to enhance the kinetics of oxygen reduction under alkaline conditions compared with bare glassy carbon, there is no significant correlation between the position of a metal on the periodic table and the electrocatalytic performance of its respective metal oxides. Moreover, it was also observed that mixed valent (+2, +3) oxides performed the poorest, compared with their respective pure metal oxides. These findings may be of paramount importance in the field of renewable energy. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Theory of novel normal and superconducting states in doped oxide high-Tc superconductors

    International Nuclear Information System (INIS)

    Dzhumanov, S.

    2001-10-01

    A consistent and complete theory of the novel normal and superconducting (SC) states of doped high-T c superconductors (HTSC) is developed by combining the continuum model of carrier self-trapping, the tight-binding model and the novel Fermi-Bose-liquid (FBL) model. The ground-state energy of carriers in lightly doped HTSC is calculated within the continuum model and adiabatic approximation using the variational method. The destruction of the long-range antiferromagnetic (AF) order at low doping x≥ x cl ≅0.015, the formation of the in-gap states or bands and novel (bi)polaronic insulating phases at x c2 ≅0.06-0.08, and the new metal- insulator transition at x≅x c2 in HTSC are studied within the continuum model of impurity (defect) centers and large (bi)polarons by using the appropriate tight-binding approximations. It is found that the three-dimensional (3d) large (bi)polarons are formed at ε ∞ /ε 0 ≤0.1 and become itinerant when the (bi)polaronic insulator-to-(bi)polaronic metal transitions occur at x x c2 . We show that the novel pseudogapped metallic and SC states in HTSC are formed at x c2 ≤x≤x p ≅0.20-0.24. We demonstrate that the large polaronic and small BCS-like pairing pseudogaps opening in the excitation spectrum of underdoped (x c2 BCS =0.125), optimally doped (x BCS o ≅0.20) and overdoped (x>x o ) HTSC above T c are unrelated to superconductivity and they are responsible for the observed anomalous optical, transport, magnetic and other properties of these HTSC. We develop the original two-stage FBL model of novel superconductivity describing the combined novel BCS-like pairing scenario of fermions and true superfluid (SF) condensation scenario of composite bosons (i.e. bipolarons and cooperons) in any Fermi-systems, where the SF condensate gap Δ B and the BCS-like pairing pseudogap Δ F have different origins. The pair and single particle condensations of attracting 3d and two- dimensional (2d) composite bosons are responsible for

  2. Low oxidation state aluminum-containing cluster anions: Cp{sup ∗}Al{sub n}H{sup −}, n = 1–3

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xinxing; Ganteför, Gerd; Bowen, Kit, E-mail: AKandalam@wcupa.edu, E-mail: kbowen@jhu.edu [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Eichhorn, Bryan [Department of Chemistry, University of Maryland, College Park, Maryland 20742 (United States); Mayo, Dennis [EOD Technology Division, Naval Surface Warfare Center, Indian Head, Maryland 20640 (United States); Sawyer, William H.; Gill, Ann F.; Kandalam, Anil K., E-mail: AKandalam@wcupa.edu, E-mail: kbowen@jhu.edu [Department of Physics, West Chester University of PA, West Chester, Pennsylvania 19383 (United States); Schnöckel, Hansgeorg [Institute of Inorganic Chemistry, Karlsruhe Institute of Technology, D-76131 Karlsruhe (Germany)

    2016-08-21

    Three new, low oxidation state, aluminum-containing cluster anions, Cp*Al{sub n}H{sup −}, n = 1–3, were prepared via reactions between aluminum hydride cluster anions, Al{sub n}H{sub m}{sup −}, and Cp*H ligands. These were characterized by mass spectrometry, anion photoelectron spectroscopy, and density functional theory based calculations. Agreement between the experimentally and theoretically determined vertical detachment energies and adiabatic detachment energies validated the computed geometrical structures. Reactions between aluminum hydride cluster anions and ligands provide a new avenue for discovering low oxidation state, ligated aluminum clusters.

  3. The Oxidation State of Fe in MORB Glasses and the Oxygen Fugacity of the Upper Mantle

    Energy Technology Data Exchange (ETDEWEB)

    E Cottrell; K Kelley

    2011-12-31

    Micro-analytical determination of Fe{sup 3+}/{Sigma}Fe ratios in mid-ocean ridge basalt (MORB) glasses using micro X-ray absorption near edge structure ({mu}-XANES) spectroscopy reveals a substantially more oxidized upper mantle than determined by previous studies. Here, we show that global MORBs yield average Fe{sup 3+}/{Sigma}Fe ratios of 0.16 {+-} 0.01 (n = 103), which trace back to primary MORB melts equilibrated at the conditions of the quartz-fayalite-magnetite (QFM) buffer. Our results necessitate an upward revision of the Fe{sup 3+}/{Sigma}Fe ratios of MORBs, mantle oxygen fugacity, and the ferric iron content of the mantle relative to previous wet chemical determinations. We show that only 0.01 (absolute, or < 10%) of the difference between Fe{sup 3+}/{Sigma}Fe ratios determined by micro-colorimety and XANES can be attributed to the Moessbauer-based XANES calibration. The difference must instead derive from a bias between micro-colorimetry performed on experimental vs. natural basalts. Co-variations of Fe{sup 3+}/{Sigma}Fe ratios in global MORB with indices of low-pressure fractional crystallization are consistent with Fe{sup 3+} behaving incompatibly in shallow MORB magma chambers. MORB Fe{sup 3+}/{Sigma}Fe ratios do not, however, vary with indices of the extent of mantle melting (e.g., Na{sub 2}O(8)) or water concentration. We offer two hypotheses to explain these observations: The bulk partition coefficient of Fe{sup 3+} may be higher during peridotite melting than previously thought, and may vary with temperature, or redox exchange between sulfide and sulfate species could buffer mantle melting at {approx} QFM. Both explanations, in combination with the measured MORB Fe{sup 3+}/{Sigma}Fe ratios, point to a fertile MORB source with greater than 0.3 wt.% Fe{sub 2}O{sub 3}.

  4. The effect of oxidation state on the absorption of ingested or inhaled plutonium

    International Nuclear Information System (INIS)

    Sullivan, M.F.; Gorham, L.S.; Ryan, J.L.

    1980-01-01

    Rats received plutonium nitrate (as 239 Pu(IV) or 239 Pu(VI) by gavage or nose-only exposure. Some of the animals were deprived of food before and/or after exposure. Results obtained indicate that there was increased retention of plutonium after exposure to 239 Pu(VI) in comparison with 239 Pu(IV). The absence of food either before and/or after inhalation exposure had no effect on the amount of 239 Pu retained by the liver and carcass. It was concluded that plutonium in its hexavalent state may under certain conditions be more readily absorbed from the GI tract, but that these conditions are unlikely to occur in human exposure. (H.K.)

  5. Solid state welding processes for an oxide dispersion strengthened nickel-chromium-aluminum alloy

    Science.gov (United States)

    Moore, T. J.

    1975-01-01

    Solid-state welding processes were evaluated for joining TD-NiCrAl (Ni-16Cr-4Al-2ThO2) alloy sheet. Both hot-press and resistance spot welding techniques were successfully applied in terms of achieving grain growth across the bond line. Less success was achieved with a resistance seam welding process. In stress-rupture shear and tensile shear tests of lap joints at 1100 C, most failures occurred in the parent material, which indicates that the weld quality was good and that the welds were not a plane of weakness. The overall weld quality was not as good as previously attained with TD-NiCr, probably because the presence of alumina at the faying surfaces and the developmental TD-NiCrAl sheet, which was not of the quality of the TD-NiCr sheet in terms of surface flatness and dimensional control.

  6. Cellulose nanofibril/reduced graphene oxide/carbon nanotube hybrid aerogels for highly flexible and all-solid-state supercapacitors.

    Science.gov (United States)

    Zheng, Qifeng; Cai, Zhiyong; Ma, Zhenqiang; Gong, Shaoqin

    2015-02-11

    A novel type of highly flexible and all-solid-state supercapacitor that uses cellulose nanofibril (CNF)/reduced graphene oxide (RGO)/carbon nanotube (CNT) hybrid aerogels as electrodes and H2SO4/poly(vinyl alcohol) (PVA) gel as the electrolyte was developed and is reported here. These flexible solid-state supercapacitors were fabricated without any binders, current collectors, or electroactive additives. Because of the porous structure of the CNF/RGO/CNT aerogel electrodes and the excellent electrolyte absorption properties of the CNFs present in the aerogel electrodes, the resulting flexible supercapacitors exhibited a high specific capacitance (i.e., 252 F g(-1) at a discharge current density of 0.5 A g(-1)) and a remarkable cycle stability (i.e., more than 99.5% of the capacitance was retained after 1000 charge-discharge cycles at a current density of 1 A g(-1)). Furthermore, the supercapacitors also showed extremely high areal capacitance, areal power density, and energy density (i.e., 216 mF cm(-2), 9.5 mW cm(-2), and 28.4 μWh cm(-2), respectively). In light of its excellent electrical performance, low cost, ease of large-scale manufacturing, and environmental friendliness, the CNF/RGO/CNT aerogel electrodes may have a promising application in the development of flexible energy-storage devices.

  7. Probing the electronic structures of low oxidation-state uranium fluoride molecules UFx- (x = 2-4)

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wei-Li [Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA; Hu, Han-Shi [Department of Chemistry & Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Tsinghua University, Beijing 100084, China; William R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352, USA; Jian, Tian [Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA; Lopez, Gary V. [Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA; Su, Jing [Department of Chemistry & Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Tsinghua University, Beijing 100084, China; Li, Jun [Department of Chemistry & Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Tsinghua University, Beijing 100084, China; William R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352, USA; Wang, Lai-Sheng [Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA

    2013-12-28

    We report the experimental observation of gaseous UFx- (x = 2-4) anions, which are investigated using photoelectron spectroscopy and relativistic quantum chemistry. Vibrationally resolved photoelectron spectra are obtained for all three species and the electron affinities of UFx (x = 2-4) are measured to be 1.16(3), 1.09(3), and 1.58(3) eV, respectively. Significant multi-electron transitions are observed in the photoelectron spectra of U(5f37s2)F2-, as a result of strong electron correlation effects of the two 7s electrons. The U-F symmetric stretching vibrational modes are resolved for the ground states of all UFx (x = 2-4) neutrals. Theoretical calculations are performed to qualitatively understand the photoelectron spectra. The entire UFx- and UFx (x = 1-6) series are considered theoretically to examine the trends of U-F bonding and the electron affinities as a function of fluorine coordination. The increased U-F bond lengths and decreased bond orders from UF2- to UF4- indicate that the U-F bonding becomes weaker as the oxidation state of U increases from I to III.

  8. Ultrasound-assisted extraction and characterization of hydrolytic and oxidative enzymes produced by solid state fermentation.

    Science.gov (United States)

    Szabo, Orsolya Erzsebet; Csiszar, Emilia; Toth, Karolina; Szakacs, George; Koczka, Bela

    2015-01-01

    Ligninolytic and hydrolytic enzymes were produced with six selected fungi on flax substrate by solid state fermentation (SSF). The extracellular enzyme production of the organisms in two SSF media was evaluated by measuring the soluble protein concentration and the filter paper, endoxylanase, 1,4-β-d-glucosidase, 1,4-β-d-endoglucanase, polygalacturonase, lignin peroxidase, manganese peroxidase and laccase activities of the clear culture solutions produced by conventional extraction from the SSF materials. The SSF material of the best enzyme producer (Trichoderma virens TUB F-498) was further investigated to enhance the enzyme recovery by low frequency ultrasound treatment. Performance of both the original and ultrasound macerated crude enzyme mixtures was evaluated in degradation of the colored lignin-containing and waxy materials of raw linen fabric. Results proved that sonication (at 40%, 60% and 80% amplitudes, for 60min) did not result in reduction in the filter paper, lignin peroxidase and laccase activities of the crude enzyme solution, but has a significant positive effect on the efficiency of enzyme extraction from the SSF material. Depending on the parameters of sonication, the enzyme activities in the extracts obtained can be increased up to 129-413% of the original activities measured in the control extracts recovered by a common magnetic stirrer. Sonication also has an effect on both the enzymatic removal of the lignin-containing color materials and hydrophobic surface layer from the raw linen. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Effect of the oxidation rate and Fe(II) state on microbial nitrate-dependent Fe(III) mineral formation

    Science.gov (United States)

    Senko, John M.; Dewers , Thomas A.; Krumholz, Lee R.

    2005-01-01

    A nitrate-dependent Fe(II)-oxidizing bacterium was isolated and used to evaluate whether Fe(II) chemical form or oxidation rate had an effect on the mineralogy of biogenic Fe(III) (hydr)oxides resulting from nitrate-dependent Fe(II) oxidation. The isolate (designated FW33AN) had 99% 16S rRNA sequence similarity to Klebsiella oxytoca. FW33AN produced Fe(III) (hydr)oxides by oxidation of soluble Fe(II) [Fe(II)sol] or FeS under nitrate-reducing conditions. Based on X-ray diffraction (XRD) analysis, Fe(III) (hydr)oxide produced by oxidation of FeS was shown to be amorphous, while oxidation of Fe(II)sol yielded goethite. The rate of Fe(II) oxidation was then manipulated by incubating various cell concentrations of FW33AN with Fe(II)sol and nitrate. Characterization of products revealed that as Fe(II) oxidation rates slowed, a stronger goethite signal was observed by XRD and a larger proportion of Fe(III) was in the crystalline fraction. Since the mineralogy of Fe(III) (hydr)oxides may control the extent of subsequent Fe(III) reduction, the variables we identify here may have an effect on the biogeochemical cycling of Fe in anoxic ecosystems.

  10. Oxidative stress and redox state-regulating enzymes have prognostic relevance in diffuse large B-cell lymphoma

    Directory of Open Access Journals (Sweden)

    Peroja Pekka

    2012-03-01

    Full Text Available Abstract Background Oxidative stress and redox-regulating enzymes may have roles both in lymphomagenesis and resistance to lymphoma therapy. Previous studies from the pre-rituximab era suggest that antioxidant enzyme expression is related to prognosis in diffuse large B-cell lymphoma (DLBCL, although these results cannot be extrapolated to patient populations undergoing modern treatment modalities. In this study we assessed expression of the oxidative stress markers 8-hydroxydeoxyguanosine (8-OHdG and nitrotyrosine and the antioxidant enzymes thioredoxin (Trx, manganese superoxide dismutase (MnSOD and glutamate-cysteine ligase (GCL via immunohistochemistry in 106 patients with DLBCL. All patients were treated with CHOP-like therapy combined with rituximab. Immunostaining results were correlated with progression-free survival, disease-specific survival and traditional prognostic factors of DLBCL. Results Strong 8-OHdG immunostaining intensity was associated with extranodal involvement (p = 0.00002, a high International Prognostic Index (p = 0.002 and strong Trx (p = 0.011 and GCL (p = 0.0003 expression. Strong Trx staining intensity was associated with poor progression-free survival (p = 0.046 and poor disease-specific survival (p = 0.015. Strong GCL immunostaining intensity predicted poor progression-free survival (p = 0.049. Patients with either strong Trx or strong nitrotyrosine expression showed significantly poorer progression-free survival (p = 0.003 and disease-specific survival (p = 0.031 compared with the other patients. Conclusions The redox state-regulating enzymes GCL and Trx are promising markers in the evaluation of DLBCL prognosis in the era of modern immunochemotherapy.

  11. Enzyme phylogenies as markers for the oxidation state of the environment: the case of respiratory arsenate reductase and related enzymes.

    Science.gov (United States)

    Duval, Simon; Ducluzeau, Anne-Lise; Nitschke, Wolfgang; Schoepp-Cothenet, Barbara

    2008-07-16

    Phylogenies of certain bioenergetic enzymes have proved to be useful tools for deducing evolutionary ancestry of bioenergetic pathways and their relationship to geochemical parameters of the environment. Our previous phylogenetic analysis of arsenite oxidase, the molybdopterin enzyme responsible for the biological oxidation of arsenite to arsenate, indicated its probable emergence prior to the Archaea/Bacteria split more than 3 billion years ago, in line with the geochemical fact that arsenite was present in biological habitats on the early Earth. Respiratory arsenate reductase (Arr), another molybdopterin enzyme involved in microbial arsenic metabolism, serves as terminal oxidase, and is thus situated at the opposite end of bioenergetic electron transfer chains as compared to arsenite oxidase. The evolutionary history of the Arr-enzyme has not been studied in detail so far. We performed a genomic search of genes related to arrA coding for the molybdopterin subunit. The multiple alignment of the retrieved sequences served to reconstruct a neighbor-joining phylogeny of Arr and closely related enzymes. Our analysis confirmed the previously proposed proximity of Arr to the cluster of polysulfide/thiosulfate reductases but also unravels a hitherto unrecognized clade even more closely related to Arr. The obtained phylogeny strongly suggests that Arr originated after the Bacteria/Archaea divergence in the domain Bacteria, and was subsequently laterally distributed within this domain. It further more indicates that, as a result of accumulation of arsenate in the environment, an enzyme related to polysulfide reductase and not to arsenite oxidase has evolved into Arr. These findings are paleogeochemically rationalized by the fact that the accumulation of arsenate over arsenite required the increase in oxidation state of the environment brought about by oxygenic photosynthesis.

  12. Source-dependent and source-independent controls on plutonium oxidation state and colloid associations in groundwater.

    Science.gov (United States)

    Buesseler, Ken O; Kaplan, Daniel I; Dai, Minhan; Pike, Steven

    2009-03-01

    Plutonium (Pu) was characterized for its isotopic composition, oxidation states, and association with colloids in groundwater samples near disposal basins in F-Area of the Savannah River Site and compared to similar samples collected six years earlier. Two sources of Pu were identified, the disposal basins, which contained a 24Pu/l39Pu isotopic signature consistent with weapons grade Pu, and 244Cm, a cocontaminant that is a progenitor radionuclide of 24Pu. 24Pu that originated primarily from 244Cm tended to be appreciably more oxidized (Pu(V/VI)), less associated with colloids (approximately 1 kDa - 0.2 microm), and more mobile than 239Pu, as suggested by our prior studies at this site. This is not evidence of isotope fractionation but rather "source-dependent" controls on 240Pu speciation which are processes that are not at equilibrium, i.e., processes that appear kinetically hindered. There were also "source-independent" controls on 239Pu speciation, which are those processes that follow thermodynamic equilibrium with their surroundings. For example, a groundwater pH increase in one well from 4.1 in 1998 to 6.1 in 2004 resulted in an order of magnitude decrease in groundwater 239Pu concentrations. Similarly, the fraction of 239Pu in the reduced Pu(III/IV) and colloidal forms increased systematically with decreases in redox condition in 2004 vs 1998. This research demonstrates the importance of source-dependent and source-independent controls on Pu speciation which would impact Pu mobility during changes in hydrological, chemical, or biological conditions on both seasonal and decadal time scales, and over short spatial scales. This implies more dynamic shifts in Pu speciation, colloids association, and transport in groundwater than commonly believed.

  13. [Adsorption of heavy metals on the surface of birnessite relationship with its Mn average oxidation state and adsorption sites].

    Science.gov (United States)

    Wang, Yan; Tan, Wen-Feng; Feng, Xiong-Han; Qiu, Guo-Hong; Liu, Fan

    2011-10-01

    Adsorption characteristics of mineral surface for heavy metal ions are largely determined by the type and amount of surface adsorption sites. However, the effects of substructure variance in manganese oxide on the adsorption sites and adsorption characteristics remain unclear. Adsorption experiments and powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) were combined to examine the adsorption characteristics of Pb2+, Cu2+, Zn2+ and Cd2+ sequestration by birnessites with different Mn average oxidation state (AOS), and the Mn AOS dependent adsorption sites and adsorption characteristics. The results show that the maximum adsorption capacity of Pb2+, Cu2+, Zn2+ and Cd2+ increased with increasing birnessite Mn AOS. The adsorption capacity followed the order of Pb2+ > Cu2+ > Zn2+ > Cd2+. The observations suggest that there exist two sites on the surface of birnessite, i. e., high-binding-energy site (HBE site) and low-binding-energy site (LBE site). With the increase of Mn AOS for birnessites, the amount of HBE sites for heavy metal ions adsorption remarkably increased. On the other hand, variation in the amount of LBE sites was insignificant. The amount of LBE sites is much more than those of HBE sites on the surface of birnessite with low Mn AOS. Nevertheless, both amounts on the surface of birnessite with high Mn AOS are very close to each other. Therefore, the heavy metal ions adsorption capacity on birnessite is largely determined by the amount of HBE sites. On birnessite surface, adsorption of Cu2+, Zn2+, and Cd2+ mostly occurred at HBE sites. In comparison with Zn2+ and Cd2+, more Cu2+ adsorbed on the LBW sites. Pb2+ adsorption maybe occupy at both LBE sites and HBE sites simultaneously.

  14. The lack of effects of zinc and nitric oxide in initial state of pilocarpine-induced seizures.

    Science.gov (United States)

    Noyan, Behzat; Jensen, Morten Skovgaard; Danscher, Gorm

    2007-07-01

    In this study we investigated whether intracerebroventricular (i.c.v.) injection of L-NAME (a nitric oxide synthase inhibitor) or CaEDTA (an extracellular zinc chelator) or the combination of the two could affect the initial phase of pilocarpine induced (2 h) seizures. Two groups of rats were used. Animals from both groups were given with i.c.v. injections of either saline (10 microl), L-NAME (150 microg/10 microl), CaEDTA (100 mM/10 microl) or L-NAME and CaEDTA. One group received pilocarpine HCl (380 mg/kg i.p.) the other served as control. Pilocarpine HCl was injected intraperitoneally 10 min later. The behavior of the animals was observed for 2h and the intensity of their seizures was scored. The rats were then sacrificed and their brains were removed and analyzed for zinc ions by using the immersion autometallography and the TSQ fluorescence staining. All the animals which received pilocarpine HCl developed seizures. Despite treatment with L-NAME and/or CaEDTA we found that the latency and the intensity of seizures were similar in both groups investigated. The distribution of stainable zinc ions and the intensity of staining in hippocampus were not affected by pilocarpine and found unchanged after L-NAME and/or CaEDTA injections in both the control animals and the pilocarpine treated animals. The data suggest that the nitric oxide system and zinc ions do not affect pilocarpine-induced seizures in their initial state.

  15. Electronic Structure and Excited-State Dynamics of an Arduengo-Type Carbene and its Imidazolone Oxidation Product.

    Science.gov (United States)

    Schmitt, Hans-Christian; Flock, Marco; Welz, Eileen; Engels, Bernd; Schneider, Heidi; Radius, Udo; Fischer, Ingo

    2017-03-02

    We describe an investigation of the excited-state dynamics of isolated 1,3-di-tert-butyl-imidazoline-2-ylidene (tBu 2 Im, C 11 H 20 N 2 , m/z=180), an Arduengo-type carbene, by time- and frequency-resolved photoionization using a picosecond laser system. The energies of several singlet and triplet excited states were calculated by time-dependent density functional theory (TD-DFT). The S 1 state of the carbene deactivates on a 100 ps time scale possibly by intersystem crossing. In the experiments we observed an additional signal at m/z=196, that was assigned to the oxidation product 1,3-di-tert-butyl-imidazolone, tBu 2 ImO. It shows a well-resolved resonance-enhanced multiphoton ionization (REMPI) spectrum with an origin located at 36951 cm -1 . Several low-lying vibrational bands could be assigned, with a lifetime that depends strongly on the excitation energy. At the origin the lifetime is longer than 3 ns, but drops to 49 ps at higher excess energies. To confirm formation of the imidazolone we also performed experiments on benzimidazolone (BzImO) for comparison. Apart from a redshift for BzImO the spectra of the two compounds are very similar. The TD-DFT values display a very good agreement with the experimental data. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Comprehensive mechanism and structure-sensitivity of ethanol oxidation on platinum: new transition-state searching method for resolving the complex reaction network.

    Science.gov (United States)

    Wang, Hui-Fang; Liu, Zhi-Pan

    2008-08-20

    Ethanol oxidation on Pt is a typical multistep and multiselectivity heterogeneous catalytic process. A comprehensive understanding of this fundamental reaction would greatly benefit design of catalysts for use in direct ethanol fuel cells and the degradation of biomass-derived oxygenates. In this work, the reaction network of ethanol oxidation on different Pt surfaces, including close-packed Pt{111}, stepped Pt{211}, and open Pt{100}, is explored thoroughly with an efficient reaction path searching method, which integrates our new transition-state searching technique with periodic density functional theory calculations. Our new technique enables the location of the transition state and saddle points for most surface reactions simply and efficiently by optimization of local minima. We show that the selectivity of ethanol oxidation on Pt depends markedly on the surface structure, which can be attributed to the structure-sensitivity of two key reaction steps: (i) the initial dehydrogenation of ethanol and (ii) the oxidation of acetyl (CH3CO). On open surface sites, ethanol prefers C-C bond cleavage via strongly adsorbed intermediates (CH2CO or CHCO), which leads to complete oxidation to CO2. However, only partial oxidizations to CH3CHO and CH3COOH occur on Pt{111}. Our mechanism points out that the open surface Pt{100} is the best facet to fully oxidize ethanol at low coverages, which sheds light on the origin of the remarkable catalytic performance of Pt tetrahexahedra nanocrystals found recently. The physical origin of the structure-selectivity is rationalized in terms of both thermodynamics and kinetics. Two fundamental quantities that dictate the selectivity of ethanol oxidation are identified: (i) the ability of surface metal atoms to bond with unsaturated C-containing fragments and (ii) the relative stability of hydroxyl at surface atop sites with respect to other sites.

  17. Experimental study of the oxide film structural phase state in the E635 and E110 alloys

    International Nuclear Information System (INIS)

    Shevyakov, A. Yu.; Shishov, V. N.; Novikov, V. V.

    2013-01-01

    The microstructure, phase and element compositions of oxide films of E110 (Zr-1%Nb) and E635 (Zr-1%Nb-0,35%Fe-1,2%Sn) alloys after autoclave tests in pure water had been studied by the method of transmission electron microscopy (TEM) with energy dispersive X-ray spectroscopy (EDS). TEM investigations of oxide film structure were carried on different oxide layers according to their thickness (near interface of “metal-oxide”, in central part of the oxide film and near outer surface) and in cross-section. The results of the tests show that oxide films of the alloys have different microstructure (grain size, fraction of tetragonal phase, content of defects, etc) and the phase compositions. The crystal structure of oxide films is mainly monoclinic, however, at the “metal-oxide” interface there are a significant fraction of the tetragonal phase. Researching of oxides on different stages of oxidation allow us to determine the kinetics of the second phase precipitate structure change: a) in E635 alloy at early oxidation stages of the amorphization process of the Laves phase precipitates begins with decreasing the content of iron and niobium; b) in E110 alloy the amorphization process of β-Nb precipitates begins at a later stage of oxidation. The influence of changes of the crystal structure and the chemical composition of the second phase precipitates on protective properties of the oxides had been determined. Researching of alloying element redistribution in E635 alloy oxide film shows that iron and niobium are concentrated in pores. Increased porosity of the E635 alloy oxide films at a later oxidation stage, in comparison with the E110 alloy, shows the influence of change composition and subsequent dissolution of the Laves phase particles on the pore formation in the oxide. (authors)

  18. Application of high-pressure techniques: stabilization and oxidation-state control of novel superconductive and related multi-layered copper oxides

    International Nuclear Information System (INIS)

    Yamauchi, H.; Karppinen, M.

    2000-01-01

    Copper oxide superconductors possess multi-layered structures with a layer sequence of -CuO 2 -(Q-CuO 2 ) n-1 -AO-(MO 1±δ ) m -AO- or -CuO 2 -B-(O 2 -B) s-1 -CuO 2 -AO-(MO 1±δ ) m -AO- along the elongated c axis. Based on this layer sequence, the known copper oxide structures are categorized as members of the homologous series, M m A r Q n-1 Cu n O m+r+2 +n ±δ (M-mr(n-1)n ; category A) or M m A 2k B s Cu 1+k O m +4k +2s±δ (M-m(2k)s (1+k ); category B). Stabilization of such structures especially in the case of high values of the n /s parameter, i.e. the higher members of the homologous series, has been demonstrated to be apparently promoted under high pressures and/or strongly oxidizing conditions. Consequently, techniques for applying both high oxygen gas pressures (10-2000 atm) and ultra-high solid-medium pressures (2-8 GPa) have been advantageously utilized in synthesizing various superconductive copper oxide phases. Especially the ultra-high solid-medium pressure synthesis carried out in the so-called cubic-anvil/belt-type apparatus has proven to be extremely successful in synthesizing novel superconductive phases. In order to achieve high partial pressures of oxygen in the solid-medium environment, 'external' oxygen-generating oxides such as KClO 4 , KClO 3 and Ag 2 O 2 are commonly added to the precursor mixtures. It is emphasized that in some cases it is possible to utilize 'internal' oxidizing agents alone, i.e. highly oxidized precursors such as BaCuO 2+δ and Ba 2 Cu 3 O 5+δ containing metal constituents common with the desired copper oxide phase only. In the present paper, the potential and applications of high-pressure techniques in synthesizing multi-layered copper oxides and related structures are reviewed and discussed with emphasis on the important 'historical' discoveries of novel phases and the present status of controlled production of high-quality samples of such phases. (author)

  19. Final Report for research grant "Development of Methods for High Specific Activity Labeling of Biomolecules Using Astatine-211 in Different Oxidation States"

    Energy Technology Data Exchange (ETDEWEB)

    Wilbur, D. Scott [Univ. of Washington, Seattle, WA (United States)

    2011-12-14

    The overall objective of this research effort was to develop methods for labeling biomolecules with higher oxidation state species of At-211. This was to be done in an effort to develop reagents that had higher in vivo stability than the present carbon-bonded At-211-labeled compounds. We were unsuccessful in that effort, as none of the approaches studied provided reagents that were stable to in vivo deastatination. However, we gained a lot of information about At-211 in higher oxidation states. The studies proved to be very difficult as small changes in pH and other conditions appeared to change the nature of the species that obtained (by HPLC retention time analyses), with many of the species being unidentifiable. The fact that there are no stable isotopes of astatine, and the chemistry of the nearest halogen iodine is quite different, made it very difficult to interpret results of some experiments. With that said, we believe that a lot of valuable information was obtained from the studies. The research effort evaluated: (1) methods for chemical oxidation of At-211, (2) approaches to chelation of oxidized At-211, and (3) approaches to oxidation of astatophenyl compounds. A major hurdle that had to be surmounted to conduct the research was the development of HPLC conditions to separate and identify the various oxidized species formed. Attempts to develop conditions for separation of iodine and astatine species by normal and reversed-phase TLC and ITLC were not successful. However, we were successful in developing conditions (from a large number of attempts) to separate oxidized forms of iodine ([I-125]iodide, [I-125]iodate and [I-125]periodate) and astatine ([At-211]astatide, [At-211]astatate, [At-211]perastatate, and several unidentified At-211 species). Information on the basic oxidation and characterization of At-211 species is provided under Objective 1. Conditions were developed to obtain new At-211 labeling method where At-211 is chelated with the DOTA and

  20. Comparison of the electronic structure of amorphous versus crystalline indium gallium zinc oxide semiconductor: structure, tail states and strain effects

    International Nuclear Information System (INIS)

    De Jamblinne de Meux, A; Genoe, J; Heremans, P; Pourtois, G

    2015-01-01

    We study the evolution of the structural and electronic properties of crystalline indium gallium zinc oxide (IGZO) upon amorphization by first-principles calculation. The bottom of the conduction band (BCB) is found to be constituted of a pseudo-band of molecular orbitals that resonate at the same energy on different atomic sites. They display a bonding character between the s orbitals of the metal sites and an anti-bonding character arising from the interaction between the oxygen and metal s orbitals. The energy level of the BCB shifts upon breaking of the crystal symmetry during the amorphization process, which may be attributed to the reduction of the coordination of the cationic centers. The top of the valence band (TVB) is constructed from anti-bonding oxygen p orbitals. In the amorphous state, they have random orientation, in contrast to the crystalline state. This results in the appearance of localized tail states in the forbidden gap above the TVB. Zinc is found to play a predominant role in the generation of these tail states, while gallium hinders their formation. Last, we study the dependence of the fundamental gap and effective mass of IGZO on mechanical strain. The variation of the gap under strain arises from the enhancement of the anti-bonding interaction in the BCB due to the modification of the length of the oxygen–metal bonds and/or to a variation of the cation coordination. This effect is less pronounced for the amorphous material compared to the crystalline material, making amorphous IGZO a semiconductor of choice for flexible electronics. Finally, the effective mass is found to increase upon strain, in contrast to regular materials. This counterintuitive variation is due to the reduction of the electrostatic shielding of the cationic centers by oxygen, leading to an increase of the overlaps between the metal orbitals at the origin of the delocalization of the BCB. For the range of strain typically met in flexible electronics, the induced

  1. Ab initio investigation of ground-states and ionic motion in particular in zirconia-based solid-oxide electrolytes

    International Nuclear Information System (INIS)

    Hirschfeld, Julian Arndt

    2012-01-01

    Electrolytes with high ionic conductivity at lower temperatures are the prerequisite for the success of Solid Oxide Fuel Cells (SOFC). One candidate is doped zirconia. In the past, the electrical resistance of zirconia based SOFC electrolytes has mainly been decreased by reducing its thickness. But there are limits to reducing the thickness and one can say that nowadays the normal ways are basically exhausted to further enhance the conductivity of well-known electrolyte materials. Hence, new approaches need to be found to discover windows of enhanced ionic conductivity. This can be achieved by understanding the quantum-mechanical oxygen transport in unconventional configurations of doped zirconia. Therefore, such an understanding is of fundamental importance. In this thesis two approaches are pursued, the investigation of the strain dependent ionic migration in zirconia based electrolytes and the designing of an electrolyte material structure with enhanced and strongly anisotropic ionic conductivity. The first approach expands the elementary understanding of oxygen migration in oxide lattices. The migration barrier of the oxygen ion jumps in zirconia is determined by applying the Density Functional Theory (DFT) calculations in connection with the Nudged Elastic Band (NEB) method. These computations show an unexpected window of decreased migration barriers at high compressive strains. Similar to other publications a decrease in the migration barrier for expansive strain is observed. But, in addition, a migration barrier decrease under high compressive strains is found beyond a maximal height of the migration barrier. A simple analytic model offers an explanation. The drop of the migration barrier at high compressions originates from the elevation of the ground-state energy. This means: Increasing ground state energies becomes an interesting alternative to facilitate ionic mobility. The second approach is based on the idea, that actually, only in the direction of ion

  2. Ab initio investigation of ground-states and ionic motion in particular in zirconia-based solid-oxide electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Hirschfeld, Julian Arndt

    2012-12-11

    Electrolytes with high ionic conductivity at lower temperatures are the prerequisite for the success of Solid Oxide Fuel Cells (SOFC). One candidate is doped zirconia. In the past, the electrical resistance of zirconia based SOFC electrolytes has mainly been decreased by reducing its thickness. But there are limits to reducing the thickness and one can say that nowadays the normal ways are basically exhausted to further enhance the conductivity of well-known electrolyte materials. Hence, new approaches need to be found to discover windows of enhanced ionic conductivity. This can be achieved by understanding the quantum-mechanical oxygen transport in unconventional configurations of doped zirconia. Therefore, such an understanding is of fundamental importance. In this thesis two approaches are pursued, the investigation of the strain dependent ionic migration in zirconia based electrolytes and the designing of an electrolyte material structure with enhanced and strongly anisotropic ionic conductivity. The first approach expands the elementary understanding of oxygen migration in oxide lattices. The migration barrier of the oxygen ion jumps in zirconia is determined by applying the Density Functional Theory (DFT) calculations in connection with the Nudged Elastic Band (NEB) method. These computations show an unexpected window of decreased migration barriers at high compressive strains. Similar to other publications a decrease in the migration barrier for expansive strain is observed. But, in addition, a migration barrier decrease under high compressive strains is found beyond a maximal height of the migration barrier. A simple analytic model offers an explanation. The drop of the migration barrier at high compressions originates from the elevation of the ground-state energy. This means: Increasing ground state energies becomes an interesting alternative to facilitate ionic mobility. The second approach is based on the idea, that actually, only in the direction of ion

  3. Expanding rare-earth oxidation state chemistry to molecular complexes of holmium(II) and erbium(II).

    Science.gov (United States)

    MacDonald, Matthew R; Bates, Jefferson E; Fieser, Megan E; Ziller, Joseph W; Furche, Filipp; Evans, William J

    2012-05-23

    The first molecular complexes of holmium and erbium in the +2 oxidation state have been generated by reducing Cp'(3)Ln [Cp' = C(5)H(4)SiMe(3); Ln = Ho (1), Er (2)] with KC(8) in the presence of 18-crown-6 in Et(2)O at -35 °C under argon. Purification and crystallization below -35 °C gave isomorphous [(18-crown-6)K][Cp'(3)Ln] [Ln = Ho (3), Er (4)]. The three Cp' ring centroids define a trigonal-planar geometry around each metal ion that is not perturbed by the location of the potassium crown cation near one ring with K-C(Cp') distances of 3.053(8)-3.078(2) Å. The metrical parameters of the three rings are indistinguishable within the error limits. In contrast to Ln(2+) complexes of Eu, Yb, Sm, Tm, Dy, and Nd, 3 and 4 have average Ln-(Cp' ring centroid) distances only 0.029 and 0.021 Å longer than those of the Ln(3+) analogues 1 and 2, a result similar to that previously reported for the 4d(1) Y(2+) complex [(18-crown-6)K][Cp'(3)Y] (5) and the 5d(1) La(2+) complex [K(18-crown-6)(Et(2)O)][Cp″(3)La] [Cp″ = 1,3-(Me(3)Si)(2)C(5)H(3)]. Surprisingly, the UV-vis spectra of 3 and 4 are also very similar to that of 5 with two broad absorptions in the visible region, suggesting that 3-5 have similar electron configurations. Density functional theory calculations on the Ho(2+) and Er(2+) species yielded HOMOs that are largely 5d(z(2)) in character and supportive of 4f(10)5d(1) and 4f(11)5d(1) ground-state configurations, respectively.

  4. Leaching of spent fuel in simulated disposal condition and separation of plutonium species as a function of oxidation state

    International Nuclear Information System (INIS)

    Kim, Seung Soo; Chun, Kwan Sik; Kang, Chul Hyung

    2000-11-01

    The influences of compacted bentonite on the leaching of spent fuel in bentonite-saturated ground water at room temperature were investigated by analyzing the components of leachates as well as the alterated surface of them. And the plutonium species was separated by ion exchangers. The amounts of Cs, Sb, Sr, Am, Ru, Pu and U released from spent fuel by bentonite-saturated solution for the initial 165 days were 2.0, 0.2, 0.2, 0.02, 0.005, 5x10 - 4, 0.05 % of inventory, respectively. These values correspond to several ∼ several tens times as much as those through bentonite block which were compacted to 1.4 g/cm 3 . The comparison of the cesium released in groundwater and bentonite-saturated solution through bentonite block is simular values, whose lower concentration in leachant indicates that most of radionuclides are retained by compacted bentonite, even though alkali metal such as Cs. The separation of plutonium species as a function of oxidation state by ion exchanger was succeed by two columns' method with packing materials as SiO - , SiO-SO 3 -

  5. FRAPCON-2: A Computer Code for the Calculation of Steady State Thermal-Mechanical Behavior of Oxide Fuel Rods

    Energy Technology Data Exchange (ETDEWEB)

    Berna, G. A; Bohn, M. P.; Rausch, W. N.; Williford, R. E.; Lanning, D. D.

    1981-01-01

    FRAPCON-2 is a FORTRAN IV computer code that calculates the steady state response of light Mater reactor fuel rods during long-term burnup. The code calculates the temperature, pressure, deformation, and tai lure histories of a fuel rod as functions of time-dependent fuel rod power and coolant boundary conditions. The phenomena modeled by the code include (a) heat conduction through the fuel and cladding, (b) cladding elastic and plastic deformation, (c) fuel-cladding mechanical interaction, (d) fission gas release, (e} fuel rod internal gas pressure, (f) heat transfer between fuel and cladding, (g) cladding oxidation, and (h) heat transfer from cladding to coolant. The code contains necessary material properties, water properties, and heat transfer correlations. FRAPCON-2 is programmed for use on the CDC Cyber 175 and 176 computers. The FRAPCON-2 code Is designed to generate initial conditions for transient fuel rod analysis by either the FRAP-T6 computer code or the thermal-hydraulic code, RELAP4/MOD7 Version 2.

  6. Phosphate Activation via Reduced Oxidation State Phosphorus (P. Mild Routes to Condensed-P Energy Currency Molecules

    Directory of Open Access Journals (Sweden)

    Claire R. Cousins

    2013-07-01

    Full Text Available The emergence of mechanisms for phosphorylating organic and inorganic molecules is a key step en route to the earliest living systems. At the heart of all contemporary biochemical systems reside reactive phosphorus (P molecules (such as adenosine triphosphate, ATP as energy currency molecules to drive endergonic metabolic processes and it has been proposed that a predecessor of such molecules could have been pyrophosphate [P2O74−; PPi(V]. Arguably the most geologically plausible route to PPi(V is dehydration of orthophosphate, Pi(V, normally a highly endergonic process in the absence of mechanisms for activating Pi(V. One possible solution to this problem recognizes the presence of reactive-P containing mineral phases, such as schreibersite [(Fe,Ni3P] within meteorites whose abundance on the early Earth would likely have been significant during a putative Hadean-Archean heavy bombardment. Here, we propose that the reduced oxidation state P-oxyacid, H-phosphite [HPO32−; Pi(III] could have activated Pi(V towards condensation via the intermediacy of the condensed oxyacid pyrophosphite [H2P2O52−; PPi(III]. We provide geologically plausible provenance for PPi(III along with evidence of its ability to activate Pi(V towards PPi(V formation under mild conditions (80 °C in water.

  7. A state-of-the-art review on nitrous oxide control from waste treatment and industrial sources.

    Science.gov (United States)

    Frutos, Osvaldo D; Quijano, Guillermo; Aizpuru, Aitor; Muñoz, Raúl

    2018-03-20

    This review aims at holistically analyzing the environmental problems associated with nitrous oxide (N 2 O) emissions by evaluating the most important sources of N 2 O and its environmental impacts. Emissions from wastewater treatment processes and the industrial production of nitric and adipic acid represent nowadays the most important anthropogenic point sources of N 2 O. Therefore, state-of-the-art strategies to mitigate the generation and release to the atmosphere of this greenhouse and O 3 -depleting gas in the waste treatment and industrial sectors are also reviewed. An updated review of the end-of-the-pipe technologies for N 2 O abatement, both in the waste treatment and industrial sectors, is herein presented and critically discussed for the first time. Despite the consistent efforts recently conducted in the development of cost-efficient and eco-friendly N 2 O abatement technologies, physical/chemical technologies still constitute the most popular treatments for the control of industrial N 2 O emissions at commercial scale. The recent advances achieved on biological N 2 O abatement based on heterotrophic denitrification have opened new opportunities for the development of eco-friendly alternatives for the treatment of N 2 O emissions. Finally, the main limitations and challenges faced by these novel N 2 O abatement biotechnologies are identified in order to pave the way for market implementation. Copyright © 2018 Elsevier Inc. All rights reserved.

  8. Mouse arsenic (+3 oxidation state) methyltransferase genotype affects metabolism and tissue dosimetry of arsenicals after arsenite administration in drinking water.

    Science.gov (United States)

    Chen, Baowei; Arnold, Lora L; Cohen, Samuel M; Thomas, David J; Le, X Chris

    2011-12-01

    Arsenic (+3 oxidation state) methyltransferase (As3mt) catalyzes methylation of inorganic arsenic (iAs) producing a number of methylated arsenic metabolites. Although methylation has been commonly considered a pathway for detoxification of arsenic, some highly reactive methylated arsenicals may contribute to toxicity associated with exposure to inorganic arsenic. Here, adult female wild-type (WT) C57BL/6 mice and female As3mt knockout (KO) mice received drinking water that contained 1, 10, or 25 ppm (mg/l) of arsenite for 33 days and blood, liver, kidney, and lung were taken for arsenic speciation. Genotype markedly affected concentrations of arsenicals in tissues. Summed concentrations of arsenicals in plasma were higher in WT than in KO mice; in red blood cells, summed concentrations of arsenicals were higher in KO than in WT mice. In liver, kidney, and lung, summed concentrations of arsenicals were greater in KO than in WT mice. Although capacity for arsenic methylation is much reduced in KO mice, some mono-, di-, and tri-methylated arsenicals were found in tissues of KO mice, likely reflecting the activity of other tissue methyltransferases or preabsorptive metabolism by the microbiota of the gastrointestinal tract. These results show that the genotype for arsenic methylation determines the phenotypes of arsenic retention and distribution and affects the dose- and organ-dependent toxicity associated with exposure to inorganic arsenic.

  9. Assigning Oxidation States to Organic Compounds via Predictions from X-ray Photoelectron Spectroscopy: A Discussion of Approaches and Recommended Improvements

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Vipul; Ganegoda, Hasitha; Engelhard, Mark H.; Terry, Jeff H.; Linford, Matthew R.

    2014-02-11

    The traditional assignment of oxidation numbers to organic molecules is problematic. Accordingly, in 1999, Calzaferri proposed a simple and elegant solution that is based on the similar electronegativities of carbon and hydrogen: hydrogen would be assigned an oxidation number of zero when bonded to carbon. Here we show that X-ray photoelectron spectroscopy (XPS), a core electron spectroscopy that is sensitive to oxidation states of elements, confirms his suggestion. In particular, in this work we: (i) list the typical rules for assigning oxidation numbers, (ii) discuss the traditional assignment of oxidation numbers to organic molecules, (iii) review Calzaferri’s solution, (iv) introduce X-ray photoelectron spectroscopy (XPS), (v) show the consistency of Calzaferri’s suggestion with XPS results, (vi) provide supporting examples from the literature, (vii) provide examples from our own research, and (viii) further confirm the Calzaferri suggestion/photoelectron spectroscopy results by discussing two organic well-known reactions. We end by reechoing Calzaferri’s suggestion that the traditional rules for assigning oxidation numbers to organic molecules be modified.

  10. Analysis of chemical bond states and electrical properties of stacked AlON/HfO{sub 2} gate oxides formed by using a layer-by-layer technique

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Wonjoon; Lee, Jonghyun; Yang, Jungyup; Kim, Chaeok; Hong, Jinpyo; Nahm, Tschanguh; Byun, Byungsub; Kim, Moseok [Hanyang University, Seoul (Korea, Republic of)

    2006-06-15

    Stacked AlON/HfO{sub 2} thin films for gate oxides in metal-oxide-semiconductor devices are successfully prepared on Si substrates by utilizing a layer-by-layer technique integrated with an off-axis RF remote plasma sputtering process at room temperature. This off-axis structure is designed to improve the uniformity and the quality of gate oxide films. Also, a layer-by-layer technique is used to control the interface layer between the gate oxide and the Si substrate. The electrical properties of our stacked films are characterized by using capacitance versus voltage and leakage current versus voltage measurements. The stacked AlON/HfO{sub 2} gate oxide exhibits a low leakage current of about 10{sup -6} A/cm{sup 2} and a high dielectric constant value of 14.26 by effectively suppressing the interface layer between gate oxide and Si substrate. In addition, the chemical bond states and the optimum thickness of each AlON and HfO{sub 2} thin film are analyzed using X-ray photoemission spectroscopy and transmission electron microscopy measurement.

  11. AUTOFLUORESCENCE IN PRIMARY RAINBOW TROUT HEPATOCYTES INTERFERES WITH MEASUREMENT OF OXIDATIVE ACTIVITY VIA THE EXOGENOUS PROBE, DCF, BUT PROVIDES INTRINSIC MEASURE OF CELLULAR OXIDATIVE STATE

    Science.gov (United States)

    The compound 2', 7'-dichlorodihydrofluoroscein diacetate is a probe commonly used to detect oxidative activity in live cells. Studies were undertaken to measure reactive oxygen species generated in freshly isolated rainbow trout hepatocytes exposed to a variety of redox cycling c...

  12. Actinide Oxidation State and O/M Ratio in Hypostoichiometric Uranium-Plutonium-Americium U0.750Pu0.246Am0.004O2-x Mixed Oxides.

    Science.gov (United States)

    Vauchy, Romain; Belin, Renaud C; Robisson, Anne-Charlotte; Lebreton, Florent; Aufore, Laurence; Scheinost, Andreas C; Martin, Philippe M

    2016-03-07

    Innovative americium-bearing uranium-plutonium mixed oxides U1-yPuyO2-x are envisioned as nuclear fuel for sodium-cooled fast neutron reactors (SFRs). The oxygen-to-metal (O/M) ratio, directly related to the oxidation state of cations, affects many of the fuel properties. Thus, a thorough knowledge of its variation with the sintering conditions is essential. The aim of this work is to follow the oxidation state of uranium, plutonium, and americium, and so the O/M ratio, in U0.750Pu0.246Am0.004O2-x samples sintered for 4 h at 2023 K in various Ar + 5% H2 + z vpm H2O (z = ∼ 15, ∼ 90, and ∼ 200) gas mixtures. The O/M ratios were determined by gravimetry, XAS, and XRD and evidenced a partial oxidation of the samples at room temperature. Finally, by comparing XANES and EXAFS results to that of a previous study, we demonstrate that the presence of uranium does not influence the interactions between americium and plutonium and that the differences in the O/M ratio between the investigated conditions is controlled by the reduction of plutonium. We also discuss the role of the homogeneity of cation distribution, as determined by EPMA, on the mechanisms involved in the reduction process.

  13. Magnetic susceptibility as a direct measure of oxidation state in LiFePO4 batteries and cyclic water gas shift reactors.

    Science.gov (United States)

    Kadyk, Thomas; Eikerling, Michael

    2015-08-14

    The possibility of correlating the magnetic susceptibility to the oxidation state of the porous active mass in a chemical or electrochemical reactor was analyzed. The magnetic permeability was calculated using a hierarchical model of the reactor. This model was applied to two practical examples: LiFePO4 batteries, in which the oxidation state corresponds with the state-of-charge, and cyclic water gas shift reactors, in which the oxidation state corresponds to the depletion of the catalyst. In LiFePO4 batteries phase separation of the lithiated and delithiated phases in the LiFePO4 particles in the positive electrode gives rise to a hysteresis effect, i.e. the magnetic permeability depends on the history of the electrode. During fast charge or discharge, non-uniform lithium distributionin the electrode decreases the hysteresis effect. However, the overall sensitivity of the magnetic response to the state-of-charge lies in the range of 0.03%, which makes practical measurement challenging. In cyclic water gas shift reactors, the sensitivity is 4 orders of magnitude higher and without phase separation, no hysteresis occurs. This shows that the method is suitable for such reactors, in which large changes of the magnetic permeability of the active material occurs.

  14. Study of crystalline morphology and phase structure in poly(styrene-b-ethylene oxide-b-styrene) triblock copolymers bu solid state RMN spin diffusion

    International Nuclear Information System (INIS)

    Mantovani, Gerson L.; Phan, Trang; Bertin, Denis; Azevedo, Eduardo R. de; Bonagamba, Tito J.

    2009-01-01

    The phase structure and crystalline morphology of a series of polystyrene-b-polyethylene oxide-b-polystyrene (PS-b- PEO-b-PS) triblock copolymers, with different compositions and molecular weights, has been studied by solid-state NMR. WAXS and DSC measurements were used to detect the presence of crystalline domains of polyethylene oxide (PEO) blocks at room temperature as a function of the copolymer composition. 1 H NMR spin diffusion analyses provided an estimation of the size of the dispersed phases of the nano structured copolymers. (author)

  15. Ionic conductivity of metal oxides : an essential property for all-solid-state Lithium-ion batteries

    NARCIS (Netherlands)

    Chen, C.; Eichel, R.-A.; Notten, P.H.L.

    2017-01-01

    Essential progress has been made for adopting metal oxides (MeO) in various energy storage and energy conversion applications. Among these, utilizing MeO in Lithium-ions batteries (LIBs) seems to be one of the most promising applications. In particular, conductive Li-containing oxides or

  16. Multiscale Transient and Steady-State Study of the Influence of Microstructure Degradation and Chromium Oxide Poisoning on Solid Oxide Fuel Cell Cathode Performance

    Science.gov (United States)

    Li, Guanchen; von Spakovsky, Michael R.; Shen, Fengyu; Lu, Kathy

    2018-01-01

    Oxygen reduction in a solid oxide fuel cell cathode involves a nonequilibrium process of coupled mass and heat diffusion and electrochemical and chemical reactions. These phenomena occur at multiple temporal and spatial scales, making the modeling, especially in the transient regime, very difficult. Nonetheless, multiscale models are needed to improve the understanding of oxygen reduction and guide cathode design. Of particular importance for long-term operation are microstructure degradation and chromium oxide poisoning both of which degrade cathode performance. Existing methods are phenomenological or empirical in nature and their application limited to the continuum realm with quantum effects not captured. In contrast, steepest-entropy-ascent quantum thermodynamics can be used to model nonequilibrium processes (even those far-from equilibrium) at all scales. The nonequilibrium relaxation is characterized by entropy generation, which can unify coupled phenomena into one framework to model transient and steady behavior. The results reveal the effects on performance of the different timescales of the varied phenomena involved and their coupling. Results are included here for the effects of chromium oxide concentrations on cathode output as is a parametric study of the effects of interconnect-three-phase-boundary length, oxygen mean free path, and adsorption site effectiveness. A qualitative comparison with experimental results is made.

  17. A 121Sb Moessbauer Study of the Chemical State of Antimony in V-Sb-O Mixed-Oxide Catalysts for the Ammoxidation of Propane

    International Nuclear Information System (INIS)

    Stievano, L.; Wagner, F. E.; Zanthoff, H. W.; Calogero, S.

    2002-01-01

    The structural changes of two representative samples of a group of V-Sb-oxide catalysts, a vanadium-rich and an antimony-rich specimen, are investigated by 121 Sb Moessbauer spectroscopy after treatment under propene or hydrogen at 673 K. The as-prepared catalysts contain both Sb(V) and Sb(III) as crystalline and microcrystalline α-Sb 2 O 4 and VSbO 4 , as well as an additional amorphous V 5+ oxide phase. The oxidation state of antimony does not change upon exposure to propene, whereas a partial reduction can be obtained by a more intense reduction under hydrogen. The Moessbauer results indicate that the antimony in VSbO 4 can be reduced more easily than that in α-Sb 2 O 4 , which appears to be more stable. These results are discussed in view of the observed depletion of vanadium at the surface of the catalyst particles under reaction conditions.

  18. Single crystal structures and theoretical calculations of uranium endohedral metallofullerenes (U@C2n , 2n = 74, 82) show cage isomer dependent oxidation states for U.

    Science.gov (United States)

    Cai, Wenting; Morales-Martínez, Roser; Zhang, Xingxing; Najera, Daniel; Romero, Elkin L; Metta-Magaña, Alejandro; Rodríguez-Fortea, Antonio; Fortier, Skye; Chen, Ning; Poblet, Josep M; Echegoyen, Luis

    2017-08-01

    Charge transfer is a general phenomenon observed for all endohedral mono-metallofullerenes. Since the detection of the first endohedral metallofullerene (EMF), La@C 82 , in 1991, it has always been observed that the oxidation state of a given encapsulated metal is always the same, regardless of the cage size. No crystallographic data exist for any early actinide endohedrals and little is known about the oxidation states for the few compounds that have been reported. Here we report the X-ray structures of three uranium metallofullerenes, U@ D 3h -C 74 , U@ C 2 (5)-C 82 and U@ C 2v (9)-C 82 , and provide theoretical evidence for cage isomer dependent charge transfer states for U. Results from DFT calculations show that U@ D 3h -C 74 and U@ C 2 (5)-C 82 have tetravalent electronic configurations corresponding to U 4+ @ D 3h -C 74 4- and U 4+ @ C 2 (5)-C 82 4- . Surprisingly, the isomeric U@ C 2v (9)-C 82 has a trivalent electronic configuration corresponding to U 3+ @ C 2v (9)-C 82 3- . These are the first X-ray crystallographic structures of uranium EMFs and this is first observation of metal oxidation state dependence on carbon cage isomerism for mono-EMFs.

  19. Effect of 50 and 80 MeV phosphorous ions on the contribution of interface and oxide state density in n-channel MOSFETs

    Energy Technology Data Exchange (ETDEWEB)

    Shinde, N.S.; Dhole, S.D.; Kanjilal, D.; Bhoraskar, V.N. E-mail: vnb@physics.unipune.ernet.in

    1999-07-02

    n-channel depletion MOS devices were irradiated with 50 and 80 MeV phosphorous ions, with different fluences varying in the range from 10{sup 11} to 10{sup 13} ions/cm{sup 2}. The pre and post irradiation I-V characteristics were measured and the corresponding threshold shift {delta}V{sub TH} was estimated. In both the cases, the drain current I{sub D} and the threshold voltage V{sub TH} were found to decrease with the ion fluence. The increase in the threshold voltage shift {delta}V{sub TH} with the ion fluence, was greater for the devices irradiated with 80 MeV ions than those irradiated with 50 MeV ions. The interface and oxide state densities were determined through the subthreshold voltage measurements. To separate the contributions of oxide and interface states towards the threshold voltage shift, the ion irradiated MOS devices were annealed at 150 deg. C. The threshold shift during annealing initially decreased and later increased with increasing annealing period. The rate of change of the interface states during annealing was higher than that of the oxide states. It was also found that depletion mode (normally ON) MOSFETs switched operation to enhancement mode (normally OFF)

  20. Susceptibility of β1 Na+-K+ pump subunit to glutathionylation and oxidative inhibition depends on conformational state of pump.

    Science.gov (United States)

    Liu, Chia-Chi; Garcia, Alvaro; Mahmmoud, Yasser A; Hamilton, Elisha J; Galougahi, Keyvan Karimi; Fry, Natasha A S; Figtree, Gemma A; Cornelius, Flemming; Clarke, Ronald J; Rasmussen, Helge H

    2012-04-06

    Glutathionylation of cysteine 46 of the β1 subunit of the Na(+)-K(+) pump causes pump inhibition. However, the crystal structure, known in a state analogous to an E2·2K(+)·P(i) configuration, indicates that the side chain of cysteine 46 is exposed to the lipid bulk phase of the membrane and not expected to be accessible to the cytosolic glutathione. We have examined whether glutathionylation depends on the conformational changes in the Na(+)-K(+) pump cycle as described by the Albers-Post scheme. We measured β1 subunit glutathionylation and function of Na(+)-K(+)-ATPase in membrane fragments and in ventricular myocytes. Signals for glutathionylation in Na(+)-K(+)-ATPase-enriched membrane fragments suspended in solutions that preferentially induce E1ATP and E1Na(3) conformations were much larger than signals in solutions that induce the E2 conformation. Ouabain further reduced glutathionylation in E2 and eliminated an increase seen with exposure to the oxidant peroxynitrite (ONOO(-)). Inhibition of Na(+)-K(+)-ATPase activity after exposure to ONOO(-) was greater when the enzyme had been in the E1Na(3) than the E2 conformation. We exposed myocytes to different extracellular K(+) concentrations to vary the membrane potential and hence voltage-dependent conformational poise. K(+) concentrations expected to shift the poise toward E2 species reduced glutathionylation, and ouabain eliminated a ONOO(-)-induced increase. Angiotensin II-induced NADPH oxidase-dependent Na(+)-K(+) pump inhibition was eliminated by conditions expected to shift the poise toward the E2 species. We conclude that susceptibility of the β1 subunit to glutathionylation depends on the conformational poise of the Na(+)-K(+) pump.

  1. Susceptibility of β1 Na+-K+ Pump Subunit to Glutathionylation and Oxidative Inhibition Depends on Conformational State of Pump*

    Science.gov (United States)

    Liu, Chia-Chi; Garcia, Alvaro; Mahmmoud, Yasser A.; Hamilton, Elisha J.; Galougahi, Keyvan Karimi; Fry, Natasha A. S.; Figtree, Gemma A.; Cornelius, Flemming; Clarke, Ronald J.; Rasmussen, Helge H.

    2012-01-01

    Glutathionylation of cysteine 46 of the β1 subunit of the Na+-K+ pump causes pump inhibition. However, the crystal structure, known in a state analogous to an E2·2K+·Pi configuration, indicates that the side chain of cysteine 46 is exposed to the lipid bulk phase of the membrane and not expected to be accessible to the cytosolic glutathione. We have examined whether glutathionylation depends on the conformational changes in the Na+-K+ pump cycle as described by the Albers-Post scheme. We measured β1 subunit glutathionylation and function of Na+-K+-ATPase in membrane fragments and in ventricular myocytes. Signals for glutathionylation in Na+-K+-ATPase-enriched membrane fragments suspended in solutions that preferentially induce E1ATP and E1Na3 conformations were much larger than signals in solutions that induce the E2 conformation. Ouabain further reduced glutathionylation in E2 and eliminated an increase seen with exposure to the oxidant peroxynitrite (ONOO−). Inhibition of Na+-K+-ATPase activity after exposure to ONOO− was greater when the enzyme had been in the E1Na3 than the E2 conformation. We exposed myocytes to different extracellular K+ concentrations to vary the membrane potential and hence voltage-dependent conformational poise. K+ concentrations expected to shift the poise toward E2 species reduced glutathionylation, and ouabain eliminated a ONOO−-induced increase. Angiotensin II-induced NADPH oxidase-dependent Na+-K+ pump inhibition was eliminated by conditions expected to shift the poise toward the E2 species. We conclude that susceptibility of the β1 subunit to glutathionylation depends on the conformational poise of the Na+-K+ pump. PMID:22354969

  2. On the superconducting state in Ba0.6K0.4BiO3 perovskite oxide

    Science.gov (United States)

    Szcześniak, D.; Kaczmarek, A. Z.; Drzazga, E. A.; Szewczyk, K. A.; Szcześniak, R.

    2018-05-01

    We report study on the superconducting state in Ba0.6K0.4BiO3 (BKBO) perovskite oxide, motivated by the inconclusive results on the pairing mechanism in this compound. Our investigations are conducted within the Migdal-Eliashberg formalism, to account for the phonon-mediated superconducting phase. The considered doping level of the discussed material corresponds to the highest critical temperature in this compound, and allows simultaneous analysis of the oxygen isotope effect, for the O16 and O18 isotopes, respectively. We found that such effect is particularly visible for the critical values of the Coulomb pseudopotential (μC⋆) , which equals to 0.18 for the O16 and 0.16 for the O18 isotope in BKBO. Moreover, we determine the size of the superconducting energy band gap (Δg) and note that obtained values (9.68 meV and 9.55 meV for the O16 and O18, respectively) are in good agreement with the experimental predictions which give Δg ∼ 8.68 meV . Finally, we calculate the characteristic dimensionless parameters, such as the zero-temperature energy gap to the critical temperature, the ratio for the specific heat, as well as the ratio associated with the zero-temperature thermodynamic critical field, which suggest occurrence of the strong-coupling and retardation effects within the phonon-mediated scenario in the analyzed material. Where possible the dimensionless ratios are compared to the experimental estimates, and agrees with these which account for the strong-coupling character of the BKBO superconductor.

  3. Recent Marijuana Use and Associations With Exhaled Nitric Oxide and Pulmonary Function in Adults in the United States.

    Science.gov (United States)

    Papatheodorou, Stefania I; Buettner, Hannah; Rice, Mary B; Mittleman, Murray A

    2016-06-01

    The medical and recreational use of marijuana is now legal in some parts of the United States; the health effects are unknown. We aimed to evaluate associations between recent marijuana use and exhaled nitric oxide (eNO) and pulmonary function. We performed a cross-sectional study of 10,327 US adults participating in the National Health and Nutrition Examination Survey in the years 2007 to 2012. We examined associations between marijuana use and eNO, FEV1, FVC, the FEV1/FVC ratio, and forced expiratory flow (midexpiratory phase) (FEF25%-75%) by weighted linear regression. In the study population, there were 4,797 never users, 4,084 past marijuana users, 555 participants who used marijuana 5 to 30 days before the examination, and 891 participants who used marijuana 0 to 4 days before the examination. Current marijuana use in the past 4 days was associated with 13% lower eNO (95% CI, -18% to 8%). FVC was higher in past users (75 mL; 95% CI, 38-112) and current users in the past 5 to 30 days (159 mL; 95% CI, 80-237) and in users within 0 to 4 days of the examination (204 mL; 95% CI, 139-270) compared with never users. All associations remained unchanged and statistically significant in sensitivity analyses excluding current and past tobacco users. Current marijuana use was associated with lower levels of eNO and higher FVC. The lower eNO in marijuana smokers suggests that short-term exposure to marijuana may, like tobacco, acutely affect the pulmonary vascular endothelium and impair airflow through the small airways. Copyright © 2016 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

  4. Oxidation state inherited from the magma source and implications for mineralization: Late Jurassic to Early Cretaceous granitoids, Central Lhasa subterrane, Tibet

    Science.gov (United States)

    Cao, MingJian; Qin, KeZhang; Li, GuangMing; Evans, Noreen J.; McInnes, Brent I. A.; Li, JinXiang; Zhao, JunXing

    2018-03-01

    Arc magmas are more oxidized than mid-ocean ridge basalts; however, there is continuing debate as to whether this higher oxidation state is inherited from the source magma or developed during late-stage magmatic differentiation processes. Well-constrained Late Jurassic to Early Cretaceous arc-related intermediate to felsic rocks derived from distinct magma sources provide us with a good opportunity to resolve this enigma. A series of granitoids from the western Central Lhasa subterrane were analyzed for whole-rock magnetic susceptibility, Fe2O3/FeO ratios, and trace elements in zircon. Compared to Late Jurassic samples (1.8 ± 2.0 × 10-4 emu g-1 oe-1, Fe3+/Fetotal = 0.32 ± 0.07, zircon Ce4+/Ce3+* = 15.0 ± 13.4), Early Cretaceous rocks show higher whole-rock magnetic susceptibility (5.8 ± 2.5 × 10-4 emu g-1 oe-1), Fe3+/Fetotal ratios (0.43 ± 0.04), and zircon Ce4+/Ce3+* values (23.9 ± 22.3). In addition, positive correlations among whole-rock magnetic susceptibility, Fe3+/Fetotal ratios, and zircon Ce4+/Ce3+* reveal a slight increase in oxidation state from fO2 = QFM to NNO in the Late Jurassic to fO2 = ˜NNO in the Early Cretaceous. Obvious linear correlation between oxidation indices (whole-rock magnetic susceptibility, zircon Ce4+/Ce3+*) and source signatures (zircon ɛHf(t), TDM C ages) indicates that the oxidation state was predominantly inherited from the source with only a minor contribution from magmatic differentiation. Thus, the sources for both the Late Jurassic and Early Cretaceous rocks were probably influenced by mantle wedge-derived magma, contributing to the increased fO2. Compared to ore-forming rocks at giant porphyry Cu deposits, the relatively low oxidation state (QFM to NNO) and negative ɛHf(t) (-16 to 0) of the studied granitoids implies relative infertility. However, this study demonstrates two potential fast and effective indices ( fO2 and ɛHf(t)) to evaluate the fertility of granitoids for porphyry-style mineralization. In an

  5. Solid-state dewetting of single- and bilayer Au-W thin films: Unraveling the role of individual layer thickness, stacking sequence and oxidation on morphology evolution

    Directory of Open Access Journals (Sweden)

    A. Herz

    2016-03-01

    Full Text Available Self-assembly of ultrathin Au, W, and Au-W bilayer thin films is investigated using a rapid thermal annealing technique in an inert ambient. The solid-state dewetting of Au films is briefly revisited in order to emphasize the role of initial film thickness. W films deposited onto SiO2 evolve into needle-like nanocrystals rather than forming particle-like agglomerates upon annealing at elevated temperatures. Transmission electron microscopy reveals that such nanocrystals actually consist of tungsten (VI oxide (WO3 which is related to an anisotropic oxide crystal growth out of the thin film. The evolution of W films is highly sensitive to the presence of any residual oxygen. Combination of both the dewetting of Au and the oxide crystal growth of WO3 is realized by using various bilayer film configurations of the immiscible Au and W. At low temperature, Au dewetting is initiated while oxide crystal growth is still suppressed. Depending on the stacking sequence of the Au-W bilayer thin film, W acts either as a substrate or as a passivation layer for the dewetting of Au. Being the ground layer, W changes the wettability of Au which clearly modifies its initial state for the dewetting. Being the top layer, W prevents Au from dewetting regardless of Au film thickness. Moreover, regular pattern formation of Au-WO3 nanoparticles is observed at high temperature demonstrating how bilayer thin film dewetting can create unique nanostructure arrangements.

  6. Solid-state dewetting of single- and bilayer Au-W thin films: Unraveling the role of individual layer thickness, stacking sequence and oxidation on morphology evolution

    Energy Technology Data Exchange (ETDEWEB)

    Herz, A., E-mail: andreas.herz@tu-ilmenau.de, E-mail: dong.wang@tu-ilmenau.de; Franz, A.; Theska, F.; Hentschel, M.; Kups, Th.; Wang, D., E-mail: andreas.herz@tu-ilmenau.de, E-mail: dong.wang@tu-ilmenau.de; Schaaf, P. [Department of Materials for Electronics and Electrical Engineering, Institute of Materials Science and Engineering and Institute of Micro- and Nanotechnologies MacroNano, TU Ilmenau, D-98693 Ilmenau (Germany)

    2016-03-15

    Self-assembly of ultrathin Au, W, and Au-W bilayer thin films is investigated using a rapid thermal annealing technique in an inert ambient. The solid-state dewetting of Au films is briefly revisited in order to emphasize the role of initial film thickness. W films deposited onto SiO{sub 2} evolve into needle-like nanocrystals rather than forming particle-like agglomerates upon annealing at elevated temperatures. Transmission electron microscopy reveals that such nanocrystals actually consist of tungsten (VI) oxide (WO{sub 3}) which is related to an anisotropic oxide crystal growth out of the thin film. The evolution of W films is highly sensitive to the presence of any residual oxygen. Combination of both the dewetting of Au and the oxide crystal growth of WO{sub 3} is realized by using various bilayer film configurations of the immiscible Au and W. At low temperature, Au dewetting is initiated while oxide crystal growth is still suppressed. Depending on the stacking sequence of the Au-W bilayer thin film, W acts either as a substrate or as a passivation layer for the dewetting of Au. Being the ground layer, W changes the wettability of Au which clearly modifies its initial state for the dewetting. Being the top layer, W prevents Au from dewetting regardless of Au film thickness. Moreover, regular pattern formation of Au-WO{sub 3} nanoparticles is observed at high temperature demonstrating how bilayer thin film dewetting can create unique nanostructure arrangements.

  7. Comparison of the oxidation state of Fe in comet 81P/Wild 2 and chondritic-porous interplanetary dust particles

    Energy Technology Data Exchange (ETDEWEB)

    Ogliore, Ryan C.; Butterworth, Anna L.; Fakra, Sirine C.; Gainsforth, Zack; Marcus, Matthew A.; Westphal, Andrew J.

    2010-07-16

    The fragile structure of chondritic-porous interplanetary dust particles (CP-IDPs) and their minimal parent-body alteration have led researchers to believe these particles originate in comets rather than asteroids where aqueous and thermal alterations have occurred. The solar elemental abundances and atmospheric entry speed of CP-IDPs also suggest a cometary origin. With the return of the Stardust samples from Jupiter-family comet 81P/Wild 2, this hypothesis can be tested. We have measured the Fe oxidation state of 15 CP-IDPs and 194 Stardust fragments using a synchrotron-based x-ray microprobe. We analyzed {approx}300 ng of Wild 2 material - three orders of magnitude more material than other analyses comparing Wild 2 and CP-IDPs. The Fe oxidation state of these two samples of material are > 2{sigma} different: the CP-IDPs are more oxidized than the Wild 2 grains. We conclude that comet Wild 2 contains material that formed at a lower oxygen fugacity than the parent-body, or parent bodies, of CP-IDPs. If all Jupiter-family comets are similar, they do not appear to be consistent with the origin of CP-IDPs. However, comets that formed from a different mix of nebular material and are more oxidized than Wild 2 could be the source of CP-IDPs.

  8. 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

  9. Facile synthesis of PbTiO3 truncated octahedra via solid-state reaction and their application in low-temperature CO oxidation by loading Pt nanoparticles

    KAUST Repository

    Yin, Simin; Zhu, Yihan; Ren, Zhaohui; Chao, Chunying; Li, Xiang; Wei, Xiao; Shen, Ge; Han, Yu; Han, Gaorong

    2014-01-01

    Perovskite PbTiO3 (PTO) nanocrystals with a truncated octahedral morphology have been prepared by a facile solid-state reaction. Pt nanoparticles preferentially nucleated on the {111} facet of PTO nanocrystals exhibit a remarkable low-temperature catalytic activity towards CO oxidation from a temperature as low as 30 °C and achieve 100% conversion at ∼50 °C. © 2014 the Partner Organisations.

  10. Signatures of Quantized Energy States in Solution-Processed Ultrathin Layers of Metal-Oxide Semiconductors and Their Devices

    KAUST Repository

    Labram, John G.; Lin, Yenhung; Zhao, Kui; Li, Ruipeng; Thomas, Stuart R.; Semple, James; Androulidaki, Maria; Sygellou, Lamprini; McLachlan, Martyn A.; Stratakis, Emmanuel; Amassian, Aram; Anthopoulos, Thomas D.

    2015-01-01

    reports of the growth of uniform, ultrathin (<5 nm) metal-oxide semiconductors from solution, however, have potentially opened the door to such phenomena manifesting themselves. Here, a theoretical framework is developed for energy quantization

  11. Study of oxidation states of the transition metals in a series of Prussian blue analogs using x-ray absorption near edge structure (XANES) spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Adak, S. [Department of Physics, New Mexico State University, Las Cruces, NM, 88003 (United States); Hartl, M., E-mail: monika.hartl@esss.se [European Spallation Source ESS AB, 22100, Lund (Sweden); Manuel Lujan Jr. Neutron Scattering Center (LANSCE-LC), Los Alamos National Laboratory, Los Alamos, NM, 87545 (United States); Daemen, L. [Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, TN, 37830 (United States); Manuel Lujan Jr. Neutron Scattering Center (LANSCE-LC), Los Alamos National Laboratory, Los Alamos, NM, 87545 (United States); Fohtung, E.; Nakotte, H. [Department of Physics, New Mexico State University, Las Cruces, NM, 88003 (United States)

    2017-01-15

    Highlights: • Systematic XANES measurements on Prussian blue analogs shows oxidation state of transition metals. • Cobal-iron bimetallic hexacyanometallates show unexpected oxidation states. • Iron(II) ions in hexacyanometallates(III) show varying spin state depending on their bond to the “N” end or “C” end of the cyanide ligand. • Thermal expansion coefficients have been linked to the XANES results. - Abstract: There have been renewed interests in metal-organic framework classes of materials such as Prussian blue analogues (PBAs) due to their potential usage in energy storage applications. In particular, due to their high surface areas, controllable structures and excellent electrochemical properties, PBAs such as hexacyanometalates M{sup II}{sub 3}[A{sup III}(CN){sub 6}]{sub 2*}nH{sub 2}O (M = Mn, Fe, Co, Ni, Cu, Zn; A = Co, Fe, Cr; n = no. of water molecules present), M{sup II}{sub 2}[Fe{sup II}(CN){sub 6}]{sub 2*}nH{sub 2}O (M = Mn, Co, Ni, Cu, Zn) and mixed hexacyanometalates(III) (Fe{sub 1-x}Co{sub x}){sub 3}[B{sup III}(CN){sub 6}]{sub 2}·nH{sub 2}O (x = 0.25, 0.5, 0.75; B = Co, Fe) could have possible usage as a new class of cathode and even anode materials for rechargeable batteries. Detailed knowledge of the oxidation states of the transition metals in PBAs is required to improve efficiency and durability of such devices. Furthermore, a link between the thermal expansion observed in these materials and the oxidation state of the transition metal is of interest to synthesize materials with a desired thermal expansion behavior, Here we demonstrate the use of Synchrotron based X-ray absorption near-edge structure (XANES) spectra to identify transition metal oxidation states. Our analysis reveals the presence of divalent, trivalent and/or mixed valence transition metals in the materials as well as high-spin and low-spin complexes.

  12. Reduced graphene oxide-wrapped MoO3 composites prepared by using metal-organic frameworks as precursor for all-solid-state flexible supercapacitors.

    Science.gov (United States)

    Cao, Xiehong; Zheng, Bing; Shi, Wenhui; Yang, Jian; Fan, Zhanxi; Luo, Zhimin; Rui, Xianhong; Chen, Bo; Yan, Qingyu; Zhang, Hua

    2015-08-26

    Reduced graphene oxide-wrapped MoO3M (rGO/MoO3 ) is prepared by a novel and simple method that is developed by using a metal-organic framework as the precursor. After a two-step annealing process, the obtained rGO/MoO3 composite is used for a high-performance supercapacitor electrode. Moreover, an all-solid-state flexible supercapacitor is fabricated based on the rGO/MoO3 composite, which shows stable performance under different bending states. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Using air quality modeling to study source-receptor relationships between nitrogen oxides emissions and ozone exposures over the United States.

    Science.gov (United States)

    Tong, Daniel Q; Muller, Nicholas Z; Kan, Haidong; Mendelsohn, Robert O

    2009-11-01

    Human exposure to ambient ozone (O(3)) has been linked to a variety of adverse health effects. The ozone level at a location is contributed by local production, regional transport, and background ozone. This study combines detailed emission inventory, air quality modeling, and census data to investigate the source-receptor relationships between nitrogen oxides (NO(x)) emissions and population exposure to ambient O(3) in 48 states over the continental United States. By removing NO(x) emissions from each state one at a time, we calculate the change in O(3) exposures by examining the difference between the base and the sensitivity simulations. Based on the 49 simulations, we construct state-level and census region-level source-receptor matrices describing the relationships among these states/regions. We find that, for 43 receptor states, cumulative NO(x) emissions from upwind states contribute more to O(3) exposures than the state's own emissions. In-state emissions are responsible for less than 15% of O(3) exposures in 90% of U.S. states. A state's NO(x) emissions can influence 2 to 40 downwind states by at least a 0.1 ppbv change in population-averaged O(3) exposure. The results suggest that the U.S. generally needs a regional strategy to effectively reduce O(3) exposures. But the current regional emission control program in the U.S. is a cap-and-trade program that assumes the marginal damage of every ton of NO(x) is equal. In this study, the average O(3) exposures caused by one ton of NO(x) emissions ranges from -2.0 to 2.3 ppm-people-hours depending on the state. The actual damage caused by one ton of NO(x) emissions varies considerably over space.

  14. Epoetin beta pegol ameliorates flow-mediated dilation with improving endothelial nitric oxide synthase coupling state in nonobese diabetic rats.

    Science.gov (United States)

    Serizawa, Kenichi; Yogo, Kenji; Tashiro, Yoshihito; Kawasaki, Ryohei; Endo, Koichi; Shimonaka, Yasushi; Hirata, Michinori

    2017-04-01

    Patients with diabetic nephropathy have a high cardiovascular mortality. Epoetin beta pegol (continuous erythropoietin receptor activator, C.E.R.A.) is a drug for the treatment of renal anemia. In this study, we investigated the effect of C.E.R.A. on vascular endothelial function as evaluated by flow-mediated dilation (FMD) and the relationship between hematopoiesis and FMD in diabetic nephropathy rats. Male Spontaneously Diabetic Torii rats (SDT, 22 weeks old) were used. C.E.R.A. (0.6, 1.2 μg/kg) was administered subcutaneously once every 2 weeks for 8 weeks. At 1 week after last administration (31 weeks old), we assessed FMD in the femoral arteries of anesthetized rats using a high-resolution ultrasound system. FMD was also measured 1 week after single C.E.R.A. treatment (5.0 μg/kg) to examine the influence of hematopoiesis. Flow-mediated dilation was significantly decreased in SDT rats before the start of C.E.R.A. treatment (22 weeks old). Repeated administration of C.E.R.A. dose-dependently improved FMD in SDT rats (31 weeks old) without changing blood glucose, nitroglycerin-induced vasodilation, or kidney function. Long-term administration of C.E.R.A. improved the state of endothelial nitric oxide synthase uncoupling in the femoral arteries of SDT rats, which showed a positive correlation with FMD. On the other hand, there was no correlation between FMD and Hb or Hct in SDT rats. Furthermore, at 1 week after single administration of C.E.R.A., FMD was not significantly improved although hemoglobin levels were comparable with levels following long-term C.E.R.A. Long-term treatment with C.E.R.A. improved FMD in SDT rats even after onset of endothelial dysfunction. © 2017 The Authors. Cardiovascular Therapeutics Published by John Wiley & Sons Ltd.

  15. A decade of changes in nitrogen oxides over regions of oil and natural gas activity in the United States

    Directory of Open Access Journals (Sweden)

    Aman Majid

    2017-12-01

    Full Text Available Nitrogen oxides (NOx = NO2 + NO are a highly regulated species that play a major role in the formation of photochemical smog. While NOx emissions are generally decreasing over the U.S. as a result of more stringent environmental policies and improved emissions control technologies, the shale oil and natural gas industry is reversing this rate of changes in certain regions. We present here a quantitative analysis of NOx levels over the seven main U.S. shale plays (Bakken, Eagle Ford, Permian, Niobrara-Codell, Marcellus-Utica, Haynesville, and Barnett between 2005 and 2015 using measurements of tropospheric NO2 from the Ozone Monitoring Instrument (OMI aboard the NASA EOS-Aura aircraft. We develop and apply a methodology that seeks to maximise pollutant signals from oil and gas activities. For reference, we also examine the national trend averaged over the lower 48 states. Consistent with previous studies, we find NOx across the U.S. is generally declining. During the low-production phase of oil and natural gas production (2005–2009, we find declining trends in tropospheric NOx that are similar to the national trend (–4.6% yr–1 in 6 of the 7 study regions (–8 to –2% yr–1. In the high-production phase (2010–15, we find an increasing NOx trend in 5 of the 7 study basins (0.4 to 4.5% yr–1 while the national trend continued to decline (–0.3% yr–1. Over the most intensive oil-producing shale plays (Bakken, Eagle Ford, Permian and Niobrara-Codell, we observe a rapid growth (1–4.5% yr–1, which correlates well (r2 = 0.6–0.9 with their annual oil production rates and/or drilling rigs. In contrast, trends across the mainly gas-producing regions (Haynesville, Barnett, and Marcellus-Utica show decreases (–0.4 to –1.7% yr–1 similar to the national trend, with the exception of the Marcellus-Utica where a slight increase (0.4 ± 0.2% yr–1 may be an indication of a small regional increase. Our study shows the important decadal

  16. A series of inorganic solid nitrogen sources for the synthesis of metal nitride clusterfullerenes: the dependence of production yield on the oxidation state of nitrogen and counter ion.

    Science.gov (United States)

    Liu, Fupin; Guan, Jian; Wei, Tao; Wang, Song; Jiao, Mingzhi; Yang, Shangfeng

    2013-04-01

    A series of nitrogen-containing inorganic solid compounds with variable oxidation states of nitrogen and counter ions have been successfully applied as new inorganic solid nitrogen sources toward the synthesis of Sc-based metal nitride clusterfullerenes (Sc-NCFs), including ammonium salts [(NH4)xH(3-x)PO4 (x = 0-2), (NH4)2SO4, (NH4)2CO3, NH4X (X = F, Cl), NH4SCN], thiocyanate (KSCN), nitrates (Cu(NO3)2, NaNO3), and nitrite (NaNO2). Among them, ammonium phosphates ((NH4)xH(3-x)PO4, x = 1-3) and ammonium thiocyanate (NH4SCN) are revealed to behave as better nitrogen sources than others, and the highest yield of Sc-NCFs is achieved when NH4SCN was used as a nitrogen source. The optimum molar ratio of Sc2O3:(NH4)3PO4·3H2O:C and Sc2O3:NH4SCN:C has been determined to be 1:2:15 and 1:3:15, respectively. The thermal decomposition products of these 12 inorganic compounds have been discussed in order to understand their different performances toward the synthesis of Sc-NCFs, and accordingly the dependence of the production yield of Sc-NCFs on the oxidation state of nitrogen and counter ion is interpreted. The yield of Sc3N@C80 (I(h) + D(5h)) per gram Sc2O3 by using the N2-based group of nitrogen sources (thiocyanate, nitrates, and nitrite) is overall much lower than those by using gaseous N2 and NH4SCN, indicating the strong dependence of the yield of Sc-NCFs on the oxidation state of nitrogen, which is attributed to the "in-situ" redox reaction taking place for the N2-based group of nitrogen sources during discharging. For NH3-based group of nitrogen sources (ammonium salts) which exhibits a (-3) oxidation states of nitrogen, their performance as nitrogen sources is found to be sensitively dependent on the anion, and this is understood by considering their difference on the thermal stability and/or decomposition rate. Contrarily, for the N2-based group of nitrogen sources, the formation of Sc-NCFs is independent to both the oxidation state of nitrogen (+3 or +5) and the

  17. Systems Ln-Fe-O ( Ln=Eu, Gd): thermodynamic properties of ternary oxides using solid-state electrochemical cells

    Science.gov (United States)

    Parida, S. C.; Rakshit, S. K.; Dash, S.; Singh, Ziley; Prasad, R.; Venugopal, V.

    2003-05-01

    The standard molar Gibbs energies of formation of LnFeO 3(s) and Ln3Fe 5O 12(s) where Ln=Eu and Gd have been determined using solid-state electrochemical technique employing different solid electrolytes. The reversible e.m.f.s of the following solid-state electrochemical cells have been measured in the temperature range from 1050 to 1255 K. Cell (I): (-)Pt / { LnFeO 3(s)+ Ln2O 3(s)+Fe(s)} // YDT/CSZ // {Fe(s)+Fe 0.95O(s)} / Pt(+); Cell (II): (-)Pt/{Fe(s)+Fe 0.95O(s)}//CSZ//{ LnFeO 3(s)+ Ln3Fe 5O 12(s)+Fe 3O 4(s)}/Pt(+); Cell (III): (-)Pt/{ LnFeO 3(s)+ Ln3Fe 5O 12(s)+Fe 3O 4(s)}//YSZ//{Ni(s)+NiO(s)}/Pt(+); and Cell(IV):(-)Pt/{Fe(s)+Fe 0.95O(s)}//YDT/CSZ//{ LnFeO 3(s)+ Ln3Fe 5O 12(s)+Fe 3O 4(s)}/Pt(+). The oxygen chemical potentials corresponding to the three-phase equilibria involving the ternary oxides have been computed from the e.m.f. data. The standard Gibbs energies of formation of solid EuFeO 3, Eu 3Fe 5O 12, GdFeO 3 and Gd 3Fe 5O 12 calculated by the least-squares regression analysis of the data obtained in the present study are given by Δ fG°m(EuFeO 3, s) /kJ mol -1 (± 3.2)=-1265.5+0.2687( T/K) (1050 ⩽ T/K ⩽ 1570), Δ fG°m(Eu 3Fe 5O 12, s)/kJ mol -1 (± 3.5)=-4626.2+1.0474( T/K) (1050 ⩽ T/K ⩽ 1255), Δ fG°m(GdFeO 3, s) /kJ mol -1 (± 3.2)=-1342.5+0.2539( T/K) (1050 ⩽ T/K ⩽ 1570), and Δ fG°m(Gd 3Fe 5O 12, s)/kJ·mol -1 (± 3.5)=-4856.0+1.0021( T/K) (1050 ⩽ T/K ⩽ 1255). The uncertainty estimates for Δ fG°m include the standard deviation in the e.m.f. and uncertainty in the data taken from the literature. Based on the thermodynamic information, oxygen potential diagrams for the systems Eu-Fe-O and Gd-Fe-O and chemical potential diagrams for the system Gd-Fe-O were computed at 1250 K.

  18. Simulation of the chemical state of irradiated oxide fuel; influence of the internal corrosion on the mechanical properties of Zry-4 tubing

    International Nuclear Information System (INIS)

    Hofmann, P.

    1979-03-01

    Zircaloy is not compatible with oxide fuel nor with some fission product elements. Therefore, chemical interaction between the irradiated oxide fuel and the Zry cladding material take place, especially at temperatures that can be reached during reactor incidents (ATWS, LOCA). In order to find out which influence the chemical interaction between the fission products and the Zry cladding material have on the mechanical properties of Zry-4 tubing out-of-pile burst experiments and creep rupture tests have been performed at temperatures >=600 0 C with short tube specimens containing simulated fission products. First of all, assessments of the chemical state of irradiated oxide fuel were performed and a method is described for introducing simulated fission product species into fresh oxide fuel for irradiation tests. As the test results of the out-of-pile studies show, only iodine can lead to a low ductility failure of the Zry-tubing at temperatures >=600 0 C. However, the influence of iodine on the deformation behavior of Zry-tubing can be neglected above 850 0 C. (orig.) [de

  19. Application of ferrous-chromate and idometric titration for the determination of copper oxidation states in the superconductor YBa2Cu3Oy

    International Nuclear Information System (INIS)

    Oku, Masaoki; Kimura, Jin; Hosoya, Minoru; Takada, Kunio; Hirokawa, Kichinosuke

    1988-01-01

    Oxidation-reduction titration methods, Fe 2+ -Cr 2 O 7 2- and I - -S 2 O 3 2- , were applied to the determination of the oxidation state of copper in the superconductor YBa 2 Cu 3 O y and related compounds. The former method presented problems in the sample dissolution and titration steps. The dissolution of the sample in low concentrations of Fe 2+ -phosphoric acid and Fe 2+ -perchloric acid takes place in two steps, the oxidation of Fe 2+ to Fe 3+ and the liberation of oxygen gas, when the liberation results in low analytical values for Cu 3+ . In addition the coexistence of cuprous ion and acids induces the oxidation of ferrous ion by dissolved oxygen and air. The problems were resolved by dissolution in 0.1 mol/l Fe 2+ -phosphoric acid and titration in an argon atmosphere. The latter method gave good results by controlling the amounts of potassium chloride, the concentration of acetic acid, and by elimination of the dissolved oxygen in acetic acid solution. The results of the two titration methods coincided with each other. (orig.)

  20. Treatment of β-Thalassemia/Hemoglobin E with Antioxidant Cocktails Results in Decreased Oxidative Stress, Increased Hemoglobin Concentration, and Improvement of the Hypercoagulable State

    Directory of Open Access Journals (Sweden)

    Orn-uma Yanpanitch

    2015-01-01

    Full Text Available Studies on the antioxidant treatment for thalassemia have reported variable outcomes. However, treatment of thalassemia with a combination of hydrophobic and hydrophilic antioxidants and an iron chelator has not been studied. This study investigated the effects of antioxidant cocktails for the treatment of β-thalassemia/hemoglobin E (HbE, which is the most common form of β-thalassemia in Southeast Asia. Sixty patients were divided into two groups receiving N-acetylcysteine, deferiprone, and either curcuminoids (CUR or vitamin E (Vit-E, and their hematological parameters, iron load, oxidative stress, and blood coagulation potential were evaluated. Patients were classified as responders if they showed the improvements of the markers of iron load and oxidative stress, otherwise as nonresponders. During treatment, the responders in both groups had significantly decreased iron load, oxidative stress, and coagulation potential and significantly increased antioxidant capacity and hemoglobin concentration. The significantly maximum increase (P<0.01 in hemoglobin concentration was 11% at month 4 in CUR group responders and 10% at month 10 in Vit-E group responders. In conclusion, the two antioxidant cocktails can improve anemia, iron overload, oxidative stress, and hypercoagulable state in β-thalassemia/HbE.

  1. Heavy metals and manganese oxides in the genesee watershed, New York state: effects of geology and land use

    Science.gov (United States)

    Whitney, P.R.

    1981-01-01

    Manganese oxide coatings on gravels from 255 sites on tributary streams in the Genesee River Watershed were analyzed for Mn, Fe, Zn, Cd, Co, Ni, Pb, and Cu. The results were compared with data on bedrock geology, surficial geology and land use, using factor analysis and stepwise multiple regression. All metals except Pb show strong positive correlation with Mn. This association results from the well-known tendency of Mn oxide precipitates to adsorb and incorporate dissolved trace metals. Pb may be present in a separate phase on the gravel surfaces; alternatively Pb abundance may be so strongly influenced by environmental factors that the effect of varying abundance of the carrier phase becomes relatively unimportant. When the effects of varying Mn abundance are allowed for, Pb and to a lesser extent Zn and Cu abundances are seen to be related to commercial, industrial and residential land use. In addition to this pollution effect, all the trace metals, Cd and Ni most strongly, tend to be more abundant in oxide coatings from streams in the forested uplands in the southern part of the area. This probably reflects increased geochemical mobility of the metals in the more acid soils and groundwater of the southern region. A strong Zn anomaly is present in streams draining areas underlain by the Lockport Formation. Oxide coatings in these streams contain up to 5% Zn, originating from disseminated sphalerite in the Lockport and secondary Zn concentrations in the overlying muck soils. The same group of metals, plus calcium and loss on ignition, were determined in the silt and clay (minus 230 mesh) fraction of stream sediments from 129 of the same sites, using a hot nitric acid leach. The amounts of manganese in the sediments are low (average 1020 ppm) and manganese oxides are, at most, of relatively minor significance in the trace-metal geochemistry of these sediments. The bulk of the trace metals in sediment appears to be associated with iron oxides, clays and organic

  2. Electronic structure of the amorphous oxide semiconductor a-InGaZnO4-x: Tauc-Lorentz optical model and origins of subgap states

    International Nuclear Information System (INIS)

    Kamiya, Toshio; Nomura, Kenji; Hosono, Hideo

    2009-01-01

    This paper discusses an optical model and subgap electronic states for a representative amorphous oxide semiconductor, InGaZnO 4 (a-IGZO). Parameterized optical models were developed based on the Tauc-Lorentz model combined with a Lorentz-type oscillator. The measured optical absorption spectra exhibit nearly linear dependences on photon energy (E) between 3 eV 0,TL ) being around 4 eV. The optimized parameters for the fixed E 0,TL of 3.7 eV are provided for four different a-IGZO films with root-mean-square errors less than 1%. Formation energies of crystalline IGZO, stoichiometric a-IGZO, oxygen deficient a-IGZO and their constituent oxides were calculated by the density functional theory using the local density approximation (LDA) and generalized gradient approximation with PBE96 functionals (PBE). PBE gives larger unit cell volumes at the ground states and better agreement in the formation energies than LDA does. The formation energies of an oxygen deficiency in a-IGZO were calculated to be 3.2-3.5 eV. The calculated electronic structures of stoichiometric a-IGZO models exhibit somewhat large dispersions for conduction bands (CB), which are not largely affected by the disordered structure in a-IGZO, while the dispersions of the valence bands (VBs) are very small, unlike the crystalline IGZO, showing that a-IGZO have strongly localized states at the VB maximums (VBMs). Oxygen-deficient a-IGZO models showed that oxygen deficiencies form both a deep localized state at 0.4-1 eV above VBM and a shallow donor state depending on local atomic configurations. An oxygen deficiency that forms a deep state breaks the dispersion of the CB, which could be an origin of the subgap states observed near CB. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Single-chamber solid oxide fuel cell technology - From its origins to today's state of the art

    Energy Technology Data Exchange (ETDEWEB)

    Khun, M. [Department of Mechanical Engineering, Ecole Polytechnique de Montreal, Montreal, Quebec, H3T 1J4 (Canada); Napporn, T. W. [Equipe Electrocatalyse, Laboratoire de Catalyse en Chimie Organique, UMR CNRS 6503, Universite de Poitiers, Poitiers (France)

    2010-07-01

    In single-chamber solid oxide fuel cells (SC-SOFCs), both anode and cathode are situated in a common gas chamber and are exposed to a mixture of fuel and oxidant. The working principle is based on the difference in catalytic activity of the electrodes for the respective anodic and cathodic reactions. The resulting difference in oxygen partial pressure between the electrodes leads to the generation of an open circuit voltage. Progress in SC-SOFC technology has enabled the generation of power outputs comparable to those of conventional SOFCs. This paper provides a detailed review of the development of SC-SOFC technology. (author)

  4. X-ray spectral determination of chemical state of phosphorus and sulfur in anodic oxide films on niobium

    International Nuclear Information System (INIS)

    Bokij, L.P.; Kostikov, Yu.P.

    1989-01-01

    Chemical forms of phosphorus and sulfur in niobium oxide anodic film, obtained by electrochemical technique using niobium in H 2 SO 4 and H 3 PO 4 aqueous solutions, are determined using data on chemical shifts of X-ray emission lines. Films represent Nb 2 O 5(1-γ) (SO 4 ) 5γ and Nb 2 O 5(1-γ) (PO 4 ) 10γ/3 (γ -share of oxygen substituted by acid anion) composition oxosalts. Electrolyte role in formation of niobium anodic oxide structure and effect of phosphorus and sulfur compounds on anodic film conductivity are determined

  5. Effect of vitamins E+C and taurine on the oxidative state of DNA in the liver of growing pigs

    DEFF Research Database (Denmark)

    Sawosz, E.; Strawa, A.; Chwalibog, Andrzej

    2004-01-01

    Growing pigs (n=21)at an initial liveweight of 30 kg were divided into three groups of 7 animals each and housed in individual cages for 100 days. The pigs were fed with similar diets (13.5 MJ ME and 178 g crude protein/kg) but with different additions of vitamins C+E and taurine. The antioxidative...... vitamins E and C supplied to diets with high energy concentrations (containing lard) can act as pro-oxidants on liver DNA in growing pigs. Taurine decreased the concentration of products from nucleotide oxidation, but in the presence of vitamin E and C, promoted hepatocyte lesions....

  6. Facile and efficient room temperature solid state reaction enabled synthesis of antimony nanoparticles embedded within reduced graphene oxide for enhanced sodium-ion storage

    Science.gov (United States)

    Zhang, Xiukui; Wu, Ping; Jiang, Li; Zhang, Xiaofang; Shi, Hongxia; Zhu, Xiaoshu; Wei, Shaohua; Zhou, Yiming

    2018-06-01

    Herein, a very simple and cost-effective solid state reaction method is employed to obtain, for the first time, the antimony nanoparticles embedded within reduced graphene oxide matrices (designated as Sb/rGO). By directly grinding antimony chloride and sodium hydroxide together at room temperature in the presence of graphene oxide (GO), Sb4O5Cl2 precursor was quickly obtained, which is evenly incorporated in the graphene oxide matrices. After subsequent chemical reduction by NaBH4, the Sb/rGO composite was successfully synthesized. The as-prepared Sb/rGO composite consists of uniform Sb nanoparticles of sub-20 nm, all of which have been wrapped in and protected by the rGO matrices. The Sb nanoparticles serve as a sufficient sodium ion reservoir while the rGO matrices provide highly efficient pathways for transport of sodium ions and electrons. Moreover, the volume expansion of Sb during sodiation can be buffered in the rGO matrices. As a result, the Sb/rGO composite exhibits excellent electrochemical performance in sodium-ion batteries (SIBs), including an enhanced cycling stability with a highly reversible charge capacity of 455 mA h g-1 after 45 cycles at 100 mA g-1, and a coulombic efficiency exceeding 98% during cycling. The findings in the present work pave the way to not only synthesize the designated promising electrode materials for high performance SIBs, but also thoroughly understand the solid-state reaction.

  7. An analysis of the effects of Mn2+ on oxidative phosphorylation in liver, brain, and heart mitochondria using state 3 oxidation rate assays

    International Nuclear Information System (INIS)

    Gunter, Thomas E.; Gerstner, Brent; Lester, Tobias; Wojtovich, Andrew P.; Malecki, Jon; Swarts, Steven G.; Brookes, Paul S.; Gavin, Claire E.; Gunter, Karlene K.

    2010-01-01

    Manganese (Mn) toxicity is partially mediated by reduced ATP production. We have used oxidation rate assays-a measure of ATP production-under rapid phosphorylation conditions to explore sites of Mn 2+ inhibition of ATP production in isolated liver, brain, and heart mitochondria. This approach has several advantages. First, the target tissue for Mn toxicity in the basal ganglia is energetically active and should be studied under rapid phosphorylation conditions. Second, Mn may inhibit metabolic steps which do not affect ATP production rate. This approach allows identification of inhibitions that decrease this rate. Third, mitochondria from different tissues contain different amounts of the components of the metabolic pathways potentially resulting in different patterns of ATP inhibition. Our results indicate that Mn 2+ inhibits ATP production with very different patterns in liver, brain, and heart mitochondria. The primary Mn 2+ inhibition site in liver and heart mitochondria, but not in brain mitochondria, is the F 1 F 0 ATP synthase. In mitochondria fueled by either succinate or glutamate + malate, ATP production is much more strongly inhibited in brain than in liver or heart mitochondria; moreover, Mn 2+ inhibits two independent sites in brain mitochondria. The primary site of Mn-induced inhibition of ATP production in brain mitochondria when succinate is substrate is either fumarase or complex II, while the likely site of the primary inhibition when glutamate plus malate are the substrates is either the glutamate/aspartate exchanger or aspartate aminotransferase.

  8. Oxidation mechanisms occurring in wines

    OpenAIRE

    Oliveira, Carla Maria; Ferreira, António César Silva; Freitas, Victor De; Silva, Artur M. S.

    2011-01-01

    The present review aims to show the state of the art on the oxidation mechanisms occurring in wines, as well as the methods to monitor, classify and diagnose wine oxidation. Wine oxidation can be divided in enzymatic oxidation and non-enzymatic oxidation. Enzymatic oxidation almost entirely occurs in grape must and is largely correlated with the content of hydroxycinnamates, such as caffeoyltartaric acid and paracoumaroyltartaric acid, and flavan-3-ols. Non-enzymatic oxidation, al...

  9. The state-of-the art of produced water treatment by oxidative advanced processes; Atual estagio de desenvolvimento dos processos oxidativos avancados para o tratamento da agua produzida

    Energy Technology Data Exchange (ETDEWEB)

    Cortes, Marcela de A.H.; Marques, Jose Jailton; Rocha, Inaura C.C. da [Universidade Federal de Sergipe (UFS), Aracaju, SE (Brazil). Dept. de Engenharia Quimica

    2008-07-01

    The oily wastewater generated in petroleum exploration contains a sort of contaminants that may cause significant environmental impact. For this reason, the number of researchers that are looking for cleaner techniques to treat this kind of wastewater is growing. The advanced oxidation processes (AOPs) are clean and non-selective processes largely used to the treatment of wastewater containing critical substances like textile dyes, pesticides, PCBs, PAHs etc. The treatment systems using AOPs can be homogeneous or heterogeneous and they may use irradiation or not. This work presents a compilation of the results found by many researchers involving AOPs potentially applicable to the treatment of produced water, as follow: H{sub 2}O{sub 2}/UV, H{sub 2}O{sub 2} / Fe{sup 2+} / UV, O{sub 3}/UV, O{sub 3}/ H{sub 2}O{sub 2} etc., showing the state-of-art of oxidation advanced processes. (author)

  10. Study concerning the compatibility of the mixture of nylon-6 and poly(propylene oxide) through solid state NMR

    International Nuclear Information System (INIS)

    Tavares, Maria I.B.; Costa, D.A.; Menezes, Sonia M.C.

    1993-01-01

    NMR has been frequently used for the determination of polymers compatibility. The utilization of the simple pulse technique together with the contact time variation technique has been enabling the evaluation of the compatibility of polymeric systems. This work presents the study of the behaviour of the mixture composed by nylon-6 with poly(propylene oxide) using these techniques. Results are presented

  11. Spring-Thaw Nitrous Oxide Emissions from Reed Canarygrass on Wetness-Prone Marginal Soil in New York State

    NARCIS (Netherlands)

    Mason, C.; Stoof, C.R.; Richards, B.K.; Rossiter, D.; Steenhuis, T.S.

    2016-01-01

    In temperate climates, a significant fraction of annual emissions of nitrous oxide (N2O) from agricultural land can occur during soil thaw in late winter and early spring. The objective of this study is to determine the impact of land use change from long-term fallow grassland to managed perennial

  12. Solid-state supercapacitors with ionic liquid gel polymer electrolyte based on poly (3, 4-ethylenedioxythiophene), carbon nanotubes, and metal oxides nanocomposites for electrical energy storage

    Science.gov (United States)

    Obeidat, Amr M.

    Clean and renewable energy systems have emerged as an important area of research having diverse and significant new applications. These systems utilize different energy storage methods such as the batteries and supercapacitors. Supercapacitors are electrochemical energy storage devices that are designed to bridge the gap between batteries and conventional capacitors. Supercapacitors which store electrical energy by electrical double layer capacitance are based on large surface area structured carbons. The materials systems in which the Faradaic reversible redox reactions store electrical energy are the transition metal oxides and electronically conducting polymers. Among the different types of conducting polymers, poly (3, 4- ethylenedioxythiophene) (PEDOT) is extensively investigated owing to its chemical and mechanical stability. Due to instability of aqueous electrolytes at high voltages and toxicity of organic electrolytes, potential of supercapacitors has not been fully exploited. A novel aspect of this work is in utilizing the ionic liquid gel polymer electrolyte to design solid-state supercapacitors for energy storage. Various electrochemical systems were investigated including graphene, PEDOT, PEDOT-carbon nanotubes, PEDOT-manganese oxide, and PEDOT-iron oxide nanocomposites. The electrochemical performance of solid-state supercapacitor devices was evaluated based on cyclic voltammetry (CV), charge-discharge (CD), prolonged cyclic tests, and electrochemical impedance spectroscopy (EIS) techniques. Raman spectroscopy technique was also utilized to analyze the bonding structure of the electrode materials. The graphene solid-state supercapacitor system displayed areal capacitance density of 141.83 mF cm-2 based on high potential window up to 4V. The PEDOT solid-state supercapacitor system was synthesized in acetonitrile and aqueous mediums achieving areal capacitance density of 219.17 mF cm-2. The hybrid structure of solid-state supercapacitors was also

  13. Immune dysfunction and increased oxidative stress state in diet-induced obese mice are reverted by nutritional supplementation with monounsaturated and n-3 polyunsaturated fatty acids.

    Science.gov (United States)

    Hunsche, Caroline; Hernandez, Oskarina; Gheorghe, Alina; Díaz, Ligia Esperanza; Marcos, Ascensión; De la Fuente, Mónica

    2018-04-01

    Obesity is associated with impaired immune defences and chronic low levels of inflammation and oxidation. In addition, this condition may lead to premature aging. The aim of the study was to evaluate the effects of a nutritional supplementation with monounsaturated and n-3 polyunsaturated fatty acids on several functions and oxidative stress parameters in peritoneal immune cells of obese mice, as well as on the life span of these animals. Obesity was induced in adult female ICR/CD1 by the administration of a high-fat diet (HFD) for 14 weeks. During the last 6 weeks of HFD feeding, one group of obese mice received the same HFD, supplemented with 1500 mg of 2-hydroxyoleic acid (2-OHOA) and another with 3000 mg of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Several functions and oxidative stress parameters of peritoneal leukocytes were evaluated. The groups of obese mice treated with 2-OHOA or with EPA and DHA showed a significant improvement in several functions such as chemotaxis, phagocytosis, digestion capacity, Natural killer activity and lymphoproliferation in response to mitogens. All of these functions, which were decreased in obese mice, increased reaching similar levels to those found in non-obese controls. Both treatments also improved oxidative stress parameters such as xanthine oxidase activity, which decreased, catalase activity and glutathione levels, which increased. These data suggest that dietary supplementation with monounsaturated and n-3 polyunsaturated fatty acids could be an effective nutritional intervention to restore the immune response and oxidative stress state, which are impaired in obese mice.

  14. System DyFeO: thermodynamic properties of ternary oxides using Calvet calorimetry and solid-state electrochemical cell

    Science.gov (United States)

    Parida, S. C.; Jacob, K. T.; Venugopal, V.

    2002-10-01

    The enthalpy increments and the standard molar Gibbs energies of formation of DyFeO 3(s) and Dy 3Fe 5O 12(s) have been measured using a Calvet micro-calorimeter and a solid oxide galvanic cell, respectively. A co-operative phase transition, related to anti-ferromagnetic to paramagnetic transformation, is apparent from the heat capacity data for DyFeO 3 at ˜648 K. A similar type of phase transition has been observed for Dy 3Fe 5O 12 at ˜560 K which is related to ferrimagnetic to paramagnetic transformation. Enthalpy increment data for DyFeO 3(s) and Dy 3Fe 5O 12(s), except in the vicinity of the second-order transition, can be represented by the following polynomial expressions: {H 0m(T)-H 0m(298.15 K)} ( J mol-1) (±1.1%)=-52754+142.9×(T ( K))+2.48×10 -3×(T ( K)) 2+2.951×10 6×(T ( K)) -1;(298.15⩽ T ( K)⩽1000) for DyFeO 3(s), and {H 0m(T)-H 0m(298.15 K)} ( J mol-1) (±1.2%)=-191048+545.0×(T ( K))+2.0×10 -5×(T ( K)) 2+8.513×10 6×(T ( K)) -1;(298.15⩽T ( K)⩽1000) for Dy 3Fe 5O 12(s). The reversible emfs of the solid-state electrochemical cells: (-)Pt/{DyFeO 3(s) + Dy 2O 3(s) + Fe(s)}//YDT/CSZ//{Fe(s) + Fe 0.95O(s)}/Pt(+) and (-)Pt/{Fe(s) + Fe 0.95O(s)}//CSZ//{DyFeO 3(s) + Dy 3Fe 5O 12(s) + Fe 3O 4(s)}/Pt(+), were measured in the temperature range from 1021 to 1250 K and 1035 to 1250 K, respectively. The standard Gibbs energies of formation of solid DyFeO 3 and Dy 3Fe 5O 12 calculated by the least squares regression analysis of the data obtained in the present study, and data for Fe 0.95O and Dy 2O 3 from the literature, are given by: Δ fG 0m( DyFeO3, s) ( kJ mol-1) (±3.2)=-1339.9+0.2473×(T ( K));(1021⩽T ( K)⩽1548) and Δ fG 0m( Dy3Fe5O12, s) ( kJ mol-1) (±3.5)=-4850.4+0.9846×(T ( K));(1035⩽T ( K)⩽1250). The uncertainty estimates for Δ fG 0m include the standard deviation in the emf and uncertainty in the data taken from the literature. Based on the thermodynamic information, oxygen potential diagram and chemical potential diagrams for

  15. Resolving surface chemical states in XPS analysis of first row transition metals, oxides and hydroxides: Cr, Mn, Fe, Co and Ni

    Energy Technology Data Exchange (ETDEWEB)

    Biesinger, Mark C., E-mail: biesingr@uwo.ca [Surface Science Western, University of Western Ontario, University of Western Ontario Research Park, Room LL31, 999 Collip Circle, London, Ontario, N6G 0J3 (Canada); ACeSSS (Applied Centre for Structural and Synchrotron Studies), University of South Australia, Mawson Lakes, SA 5095 (Australia); Payne, Brad P. [Department of Chemistry, University of Western Ontario, London, Ontario, N6A 5B7 (Canada); Grosvenor, Andrew P. [Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, S7N 5C9 (Canada); Lau, Leo W.M. [Surface Science Western, University of Western Ontario, University of Western Ontario Research Park, Room LL31, 999 Collip Circle, London, Ontario, N6G 0J3 (Canada); Department of Chemistry, University of Western Ontario, London, Ontario, N6A 5B7 (Canada); Gerson, Andrea R.; Smart, Roger St.C. [ACeSSS (Applied Centre for Structural and Synchrotron Studies), University of South Australia, Mawson Lakes, SA 5095 (Australia)

    2011-01-15

    Chemical state X-ray photoelectron spectroscopic analysis of first row transition metals and their oxides and hydroxides is challenging due to the complexity of their 2p spectra resulting from peak asymmetries, complex multiplet splitting, shake-up and plasmon loss structure, and uncertain, overlapping binding energies. Our previous paper [M.C. Biesinger et al., Appl. Surf. Sci. 257 (2010) 887-898.] in which we examined Sc, Ti, V, Cu and Zn species, has shown that all the values of the spectral fitting parameters for each specific species, i.e. binding energy (eV), full wide at half maximum (FWHM) value (eV) for each pass energy, spin-orbit splitting values and asymmetric peak shape fitting parameters, are not all normally provided in the literature and data bases, and are necessary for reproducible, quantitative chemical state analysis. A more consistent, practical and effective approach to curve fitting was developed based on a combination of (1) standard spectra from quality reference samples, (2) a survey of appropriate literature databases and/or a compilation of literature references and (3) specific literature references where fitting procedures are available. This paper extends this approach to the chemical states of Cr, Mn, Fe, Co and Ni metals, and various oxides and hydroxides where intense, complex multiplet splitting in many of the chemical states of these elements poses unique difficulties for chemical state analysis. The curve fitting procedures proposed use the same criteria as proposed previously but with the additional complexity of fitting of multiplet split spectra which has been done based on spectra of numerous reference materials and theoretical XPS modeling of these transition metal species. Binding energies, FWHM values, asymmetric peak shape fitting parameters, multiplet peak separation and peak area percentages are presented. The procedures developed can be utilized to remove uncertainties in the analysis of surface states in nano

  16. Microwave-Based Oxidation State and Soot Loading Determination on Gasoline Particulate Filters with Three-Way Catalyst Coating for Homogenously Operated Gasoline Engines

    Directory of Open Access Journals (Sweden)

    Markus Dietrich

    2015-09-01

    Full Text Available Recently, a novel method emerged to determine the oxygen storage degree of three way catalysts (TWC by a microwave-based method. Up to now, this method has been investigated only in lab-scale reactors or under steady state conditions. This work expands those initial studies. A TWC-coated gasoline particulate filter was investigated in a dynamic engine test bench simulating a typical European driving cycle (NEDC. It could be shown that both the oxygen storage degree and the soot loading can be monitored directly, but not simultaneously due to their competitive effects. Under normal driving conditions, no soot accumulation was observed, related to the low raw emissions and the catalytic coating of the filter. For the first time, the quality factor of the cavity resonator in addition to the resonance frequency was used, with the benefit of less cross sensitivity to inconstant temperature and water. Therefore, a temperature dependent calibration of the microwave signal was created and applied to monitor the oxidation state in transient driving cycles. The microwave measurement mirrors the oxidation state determined by lambda probes and can be highly beneficial in start-stop phases (where lambda-probes do not work and to determine the oxygen storage capacity (OSC without unnecessary emissions.

  17. Microwave-Based Oxidation State and Soot Loading Determination on Gasoline Particulate Filters with Three-Way Catalyst Coating for Homogenously Operated Gasoline Engines.

    Science.gov (United States)

    Dietrich, Markus; Jahn, Christoph; Lanzerath, Peter; Moos, Ralf

    2015-09-02

    Recently, a novel method emerged to determine the oxygen storage degree of three way catalysts (TWC) by a microwave-based method. Up to now, this method has been investigated only in lab-scale reactors or under steady state conditions. This work expands those initial studies. A TWC-coated gasoline particulate filter was investigated in a dynamic engine test bench simulating a typical European driving cycle (NEDC). It could be shown that both the oxygen storage degree and the soot loading can be monitored directly, but not simultaneously due to their competitive effects. Under normal driving conditions, no soot accumulation was observed, related to the low raw emissions and the catalytic coating of the filter. For the first time, the quality factor of the cavity resonator in addition to the resonance frequency was used, with the benefit of less cross sensitivity to inconstant temperature and water. Therefore, a temperature dependent calibration of the microwave signal was created and applied to monitor the oxidation state in transient driving cycles. The microwave measurement mirrors the oxidation state determined by lambda probes and can be highly beneficial in start-stop phases (where lambda-probes do not work) and to determine the oxygen storage capacity (OSC) without unnecessary emissions.

  18. Determination of bulk and interface density of states in metal oxide semiconductor thin-film transistors by using capacitance-voltage characteristics

    Science.gov (United States)

    Wei, Xixiong; Deng, Wanling; Fang, Jielin; Ma, Xiaoyu; Huang, Junkai

    2017-10-01

    A physical-based straightforward extraction technique for interface and bulk density of states in metal oxide semiconductor thin film transistors (TFTs) is proposed by using the capacitance-voltage (C-V) characteristics. The interface trap density distribution with energy has been extracted from the analysis of capacitance-voltage characteristics. Using the obtained interface state distribution, the bulk trap density has been determined. With this method, for the interface trap density, it is found that deep state density nearing the mid-gap is approximately constant and tail states density increases exponentially with energy; for the bulk trap density, it is a superposition of exponential deep states and exponential tail states. The validity of the extraction is verified by comparisons with the measured current-voltage (I-V) characteristics and the simulation results by the technology computer-aided design (TCAD) model. This extraction method uses non-numerical iteration which is simple, fast and accurate. Therefore, it is very useful for TFT device characterization.

  19. Reversal magnetization dependence with the Cr and Fe oxidation states in YFe1−xCrxO3 (0≤x≤1) perovskites

    International Nuclear Information System (INIS)

    Fabian, F.A.; Pedra, P.P.; Moura, K.O.; Duque, J.G.S.; Meneses, C.T.

    2016-01-01

    In this work, we have carried out a detailed study of the magnetic and structural properties of YFe 1−x Cr x O 3 (0≤x≤1) samples with orthorhombic structure obtained by co-precipitation method. Analysis of X-ray diffraction data using Rietveld refinement show that all samples present an orthorhombic crystal system with space group Pnma. Besides, we have observed a reduction of unit cell volume with increasing of the Cr concentration. SEM images show the formation of grains of micrometer order. X-ray Absorption near edge spectroscopy (XANES) measurements show a shift of absorption edge which can be indicate there is (i) different oxidation states to Fe and Cr ions and/or (ii) a changing in the point symmetry of Fe and Cr ions to the compounds. The magnetization measurements indicate a continuous decreasing of the magnetic transition temperature as function of chromium doping. The reversal magnetization effect was observed to concentrations around x=0.5. Besides, the deviation of the Curie–Weiss law and a weak ferromagnetic behavior observed at room temperature in the M vs H curves can be attributed to the strong magnetic interactions between the transition metals with different oxidation states. - Highlights: • YFe 1−x Cr x O 3 (0≤x≤1) samples were synthesized by co-precipitation method. • XRD dates showed a reduction of unit cell volume with addition of Cr. • XANES dates showed difference in the oxidation states to Cr and Fe. • MZFC-MFC indicate a decreasing of the T N as function of chromium doping. • MFC curve for x=0.5 concentration was observed the reverse magnetization effect.

  20. Defect states and room temperature ferromagnetism in cerium oxide nanopowders prepared by decomposition of Ce-propionate

    DEFF Research Database (Denmark)

    Mihalache, V.; Grivel, J. C.; Secu, M.

    2018-01-01

    . An improvement of ferromagnetism and intensity of defect-related PL emission was observed when annealing the products in which nanocrystalline cerium oxide coexists with Ce - oxicarbonate traces, Ce2O2CO3. The experimental results were explained based on the following considerations: room temperature......Four batches of cerium oxide powders (with nanocrystallite size of 6.9 nm–572 nm) were prepared from four precursor nanopowders by thermal decomposition of Ce-propionate and annealing in air between 250 °C–1200 °C for 10 min–240 min. Ceria formation reactions, structure, vibrational, luminescence...... and magnetic properties were investigated by differential scanning calorimetry, x-ray diffraction, electron microscopy, infrared spectroscopy, photoluminescence and SQUID. All the samples exhibit room temperature ferromagnetism, RTFM, (with coercivity, Hc, of 8 Oe - 121 Oe and saturation magnetization, Ms...

  1. Kinetic Studies on State of the Art Solid Oxide Cells – A Comparison between Hydrogen/Steam and Reformate Fuels

    DEFF Research Database (Denmark)

    Njodzefon, Jean-Claude; Graves, Christopher R.; Mogensen, Mogens Bjerg

    2015-01-01

    Electrochemical reaction kinetics at the electrodes of Solid Oxide Cells (SOCs) were investigated at 700 °C for two cells with different fuel electrode microstructures as well as on a third cell with a reduced active electrode area. Three fuel mixtures were investigated – hydrogen/steam and refor......Electrochemical reaction kinetics at the electrodes of Solid Oxide Cells (SOCs) were investigated at 700 °C for two cells with different fuel electrode microstructures as well as on a third cell with a reduced active electrode area. Three fuel mixtures were investigated – hydrogen....../steam fuel split into two processes with opposing temperature behavior in the reformate fuels. An 87.5% reduction in active electrode area diminishes the gas conversion impedance in the hydrogen/steam fuel at high fuel flow rates. In both reformates, the second and third lowest frequency processes merged...

  2. Next Generation Energetic Materials: New Cluster Hydrides and Metastable Alloys of Aluminum in Very Low Oxidation States

    Science.gov (United States)

    2016-10-01

    knowledge of barrier heights . For the reactions of 3O2 with closed- and open-shell Alx − and Gax − clusters, these cal- culations are complicated not only...nanoparticle nucleation on functionalized graphene surfactants from aluminum monochloride solutions. This data shows a strong affinity of AlCl units for... graphene vacancy sites; adsorption of AlCl to the site results in oxidative insertion into the Al–Cl bond and formation of an Al(III) center. Preliminary

  3. Lasing of a Solid-State Active Element Based on Anodized Aluminum Oxide Film Doped with Rhodamine 6G

    Science.gov (United States)

    Shelkovnikov, V. V.; Lyubas, G. A.; Korotaev, S. V.; Kopylova, T. N.; Tel'minov, E. N.; Gadirov, R. M.; Nikonova, E. N.; Nikonov, S. Yu.; Solodova, T. A.; Novikov, V. A.

    2017-04-01

    Spectral-luminescent and lasing characteristics of rhodamine 6G in porous aluminum oxide films anodized under various conditions are investigated. Lasing is obtained without external resonator in the longitudinal scheme under excitation by the second harmonic of Nd3+:YAG-laser radiation. The threshold pump power densities are in the range 3.5-15 MW/cm2 depending on the anodizing conditions. Wherein, the lasing line narrows down from 12 to 5 nm.

  4. “Covalent Hydration” Reactions in Model Monomeric Ru 2,2'-Bipyridine Complexes: Thermodynamic Favorability as a Function of Metal Oxidation and Overall Spin States

    Energy Technology Data Exchange (ETDEWEB)

    Ozkanlar, Abdullah; Cape, Jonathan L.; Hurst, James K.; Clark, Aurora E.

    2011-09-05

    Density functional theory (DFT) has been used to investigate the plausibility of water addition to the simple mononuclear ruthenium complexes, [(NH{sub 3}){sub 3}(bpy)Ru=O]{sup 2+}/{sup 3+} and [(NH{sub 3}){sub 3}(bpy)RuOH]{sup 3+}, in which the OH fragment adds to the 2,2{prime}-bipyridine (bpy) ligand. Activation of bpy toward water addition has frequently been postulated within the literature, although there exists little definitive experimental evidence for this type of 'covalent hydration'. In this study, we examine the energetic dependence of the reaction upon metal oxidation state, overall spin state of the complex, as well as selectivity for various positions on the bipyridine ring. The thermodynamic favorability is found to be highly dependent upon all three parameters, with free energies of reaction that span favorable and unfavorable regimes. Aqueous addition to [(NH{sub 3}){sub 3}(bpy)Ru=O]{sup 3+} was found to be highly favorable for the S = 1/2 state, while reduction of the formal oxidation state on the metal center makes the reaction highly unfavorable. Examination of both facial and meridional isomers reveals that when bipyridine occupies the position trans to the ruthenyl oxo atom, reactivity toward OH addition decreases and the site preferences are altered. The electronic structure and spectroscopic signatures (EPR parameters and simulated spectra) have been determined to aid in recognition of 'covalent hydration' in experimental systems. EPR parameters are found to uniquely characterize the position of the OH addition to the bpy as well as the overall spin state of the system.

  5. Constitutively Elevated Salicylic Acid Levels Alter Photosynthesis and Oxidative State but Not Growth in Transgenic Populus[C][W

    Science.gov (United States)

    Xue, Liang-Jiao; Guo, Wenbing; Yuan, Yinan; Anino, Edward O.; Nyamdari, Batbayar; Wilson, Mark C.; Frost, Christopher J.; Chen, Han-Yi; Babst, Benjamin A.; Harding, Scott A.; Tsai, Chung-Jui

    2013-01-01

    Salicylic acid (SA) has long been implicated in plant responses to oxidative stress. SA overproduction in Arabidopsis thaliana leads to dwarfism, making in planta assessment of SA effects difficult in this model system. We report that transgenic Populus tremula × alba expressing a bacterial SA synthase hyperaccumulated SA and SA conjugates without negative growth consequences. In the absence of stress, endogenously elevated SA elicited widespread metabolic and transcriptional changes that resembled those of wild-type plants exposed to oxidative stress-promoting heat treatments. Potential signaling and oxidative stress markers azelaic and gluconic acids as well as antioxidant chlorogenic acids were strongly coregulated with SA, while soluble sugars and other phenylpropanoids were inversely correlated. Photosynthetic responses to heat were attenuated in SA-overproducing plants. Network analysis identified potential drivers of SA-mediated transcriptome rewiring, including receptor-like kinases and WRKY transcription factors. Orthologs of Arabidopsis SA signaling components NON-EXPRESSOR OF PATHOGENESIS-RELATED GENES1 and thioredoxins were not represented. However, all members of the expanded Populus nucleoredoxin-1 family exhibited increased expression and increased network connectivity in SA-overproducing Populus, suggesting a previously undescribed role in SA-mediated redox regulation. The SA response in Populus involved a reprogramming of carbon uptake and partitioning during stress that is compatible with constitutive chemical defense and sustained growth, contrasting with the SA response in Arabidopsis, which is transient and compromises growth if sustained. PMID:23903318

  6. Numerical Research of Nitrogen Oxides Formation for Justification of Modernization of P-49 Nazarovsky State District Power Plant Boiler on the Low-temperature Swirl Technology of Burning

    Science.gov (United States)

    Trinchenko, A. A.; Paramonov, A. P.; Skouditskiy, V. E.; Anoshin, R. G.

    2017-11-01

    Compliance with increasingly stringent normative requirements to the level of pollutants emissions when using organic fuel in the energy sector as a main source of heat, demands constant improvement of the boiler and furnace equipment and the power equipment in general. The requirements of the current legislation in the field of environmental protection prescribe compliance with established emission standards for both new construction and the improvement of energy equipment. The paper presents the results of numerical research of low-temperature swirl burning in P-49 Nazarovsky state district power plant boiler. On the basis of modern approaches of the diffusion and kinetic theory of burning and the analysis physical and chemical processes of a fuel chemically connected energy transition in thermal, generation and transformation of gas pollutants, the technological method of nitrogen oxides decomposition on the surface of carbon particles with the formation of environmentally friendly carbonic acid and molecular nitrogen is considered during the work of low-temperature swirl furnace. With the use of the developed model, methodology and computer program, variant calculations of the combustion process were carried out and a quantitative estimate of the emission level of the nitrogen oxides of the boiler being modernized. The simulation results the and the experimental data obtained during the commissioning and balance tests of the P-49 boiler with a new furnace are confirmed that the organization of swirl combustion has allowed to increase the efficiency of work, to reduce slagging, to significantly reduce nitrogen oxide emissions, to improve ignition and burnout of fuel.

  7. Organic aerosol in the summertime southeastern United States: components and their link to volatility distribution, oxidation state and hygroscopicity

    Directory of Open Access Journals (Sweden)

    E. Kostenidou

    2018-04-01

    Full Text Available The volatility distribution of the organic aerosol (OA and its sources during the Southern Oxidant and Aerosol Study (SOAS; Centreville, Alabama was constrained using measurements from an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS and a thermodenuder (TD. Positive matrix factorization (PMF analysis was applied on both the ambient and thermodenuded high-resolution mass spectra, leading to four factors: more oxidized oxygenated OA (MO-OOA, less oxidized oxygenated OA (LO-OOA, an isoprene epoxydiol (IEPOX-related factor (isoprene-OA and biomass burning OA (BBOA. BBOA had the highest mass fraction remaining (MFR at 100 °C, followed by the isoprene-OA, and the LO-OOA. Surprisingly the MO-OOA evaporated the most in the TD. The estimated effective vaporization enthalpies assuming an evaporation coefficient equal to unity were 58 ± 13 kJ mol−1 for the LO-OOA, 89 ± 10 kJ mol−1 for the MO-OOA, 55 ± 11 kJ mol−1 for the BBOA, and 63 ± 15 kJ mol−1 for the isoprene-OA. The estimated volatility distribution of all factors covered a wide range including both semi-volatile and low-volatility components. BBOA had the lowest average volatility of all factors, even though it had the lowest O  :  C ratio among all factors. LO-OOA was the more volatile factor and its high MFR was due to its low enthalpy of vaporization according to the model. The isoprene-OA factor had intermediate volatility, quite higher than suggested by a few other studies. The analysis suggests that deducing the volatility of a factor only from its MFR could lead to erroneous conclusions. The oxygen content of the factors can be combined with their estimated volatility and hygroscopicity to provide a better view of their physical properties.

  8. Impairment of Several Immune Functions and Redox State in Blood Cells of Alzheimer’s Disease Patients. Relevant Role of Neutrophils in Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Carmen Vida

    2018-01-01

    Full Text Available Since aging is considered the most risk factor for sporadic Alzheimer’s Disease (AD, the age-related impairment of the immune system (immunosenescence, based on a chronic oxidative-inflammatory stress situation, could play a key role in the development and progression of AD. Although AD is accompanied by systemic disturbance, reflecting the damage in the brain, the changes in immune response and redox-state in different types of blood cells in AD patients have been scarcely studied. The aim was to analyze the variations in several immune functions and oxidative-inflammatory stress and damage parameters in both isolated peripheral neutrophils and mononuclear blood cells, as well as in whole blood cells, from patients diagnosed with mild (mAD and severe AD, and of age-matched controls (elderly healthy subjects as well as of adult controls. The cognitive decline of all subjects was determined by Mini-Mental State Examination (MMSE test (mAD stage was established at 20 ≤ MMSE ≤ 23 score; AD stage at <18 MMSE; elderly subjects >27 MMSE. The results showed an impairment of the immune functions of human peripheral blood neutrophils and mononuclear cells of mAD and AD patients in relation to healthy elderly subjects, who showed the typical immunosenescence in comparison with the adult individuals. However, several alterations were only observed in severe AD patients (lower chemotaxis, lipopolysaccharide lymphoproliferation, and interleukin (IL-10 release; higher basal proliferation, tumor necrosis factor (TNF-α release, and IL-10/TNF-α ratio, others only in mAD subjects (higher adherence, meanwhile others appeared in both mAD and AD patients (lower phytohemaglutinin lymphoproliferation and higher IL-6 release. This impairment of immune functions could be mediated by: (1 the higher oxidative stress and damage also observed in blood cells from mAD and AD patients and in isolated neutrophils [lower glutathione (GSH levels, high oxidized

  9. Direct observation of electronic and nuclear ground state splitting in external magnetic field by inelastic neutron scattering on oxidized ferrocene and ferrocene containing polymers

    Science.gov (United States)

    Appel, Markus; Frick, Bernhard; Elbert, Johannes; Gallei, Markus; Stühn, Bernd

    2015-01-01

    The quantum mechanical splitting of states by interaction of a magnetic moment with an external magnetic field is well known, e.g., as Zeeman effect in optical transitions, and is also often seen in magnetic neutron scattering. We report excitations observed in inelastic neutron spectroscopy on the redox-responsive polymer poly(vinylferrocene). They are interpreted as splitting of the electronic ground state in the organometallic ferrocene units attached to the polymer chain where a magnetic moment is created by oxidation. In a second experiment using high resolution neutron backscattering spectroscopy we observe the hyperfine splitting, i.e., interaction of nuclear magnetic moments with external magnetic fields leading to sub-μeV excitations observable in incoherent neutron spin-flip scattering on hydrogen and vanadium nuclei.

  10. Generic origin of subgap states in transparent amorphous semiconductor oxides illustrated for the cases of In-Zn-O and In-Sn-O

    Energy Technology Data Exchange (ETDEWEB)

    Koerner, Wolfgang; Urban, Daniel F.; Elsaesser, Christian [Fraunhofer Institute for Mechanics of Materials IWM, Woehlerstr. 11, 79108, Freiburg (Germany)

    2015-07-15

    We present a microscopic interpretation for the appearance and behaviour of subgap states in stoichiometric and oxygen-deficient, amorphous In-Zn-O (a-IZO) and In-Sn-O (a-ITO) derived from a density functional theory analysis using a self-interaction-correction scheme. Our findings concerning the defect structures and the resulting deep levels are qualitatively similar to earlier results on a-IGZO and a-ZTO and in agreement with recent experimental results. Based on our extensive set of DFT results for In-, Sn-, Zn- based oxides we develop a general concept of the subgap states which is applicable to these systems. Electronic defect levels in the lower half of the band gap are created by undercoordinated oxygen atoms while local oxygen deficiencies cause defect levels in the upper part of the band gap. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Generic origin of subgap states in transparent amorphous semiconductor oxides illustrated for the cases of In-Zn-O and In-Sn-O

    International Nuclear Information System (INIS)

    Koerner, Wolfgang; Urban, Daniel F.; Elsaesser, Christian

    2015-01-01

    We present a microscopic interpretation for the appearance and behaviour of subgap states in stoichiometric and oxygen-deficient, amorphous In-Zn-O (a-IZO) and In-Sn-O (a-ITO) derived from a density functional theory analysis using a self-interaction-correction scheme. Our findings concerning the defect structures and the resulting deep levels are qualitatively similar to earlier results on a-IGZO and a-ZTO and in agreement with recent experimental results. Based on our extensive set of DFT results for In-, Sn-, Zn- based oxides we develop a general concept of the subgap states which is applicable to these systems. Electronic defect levels in the lower half of the band gap are created by undercoordinated oxygen atoms while local oxygen deficiencies cause defect levels in the upper part of the band gap. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Steady-State Growth under Inorganic Carbon Limitation Conditions Increases Energy Consumption for Maintenance and Enhances Nitrous Oxide Production in Nitrosomonas europaea.

    Science.gov (United States)

    Mellbye, Brett L; Giguere, Andrew; Chaplen, Frank; Bottomley, Peter J; Sayavedra-Soto, Luis A

    2016-06-01

    Nitrosomonas europaea is a chemolithoautotrophic bacterium that oxidizes ammonia (NH3) to obtain energy for growth on carbon dioxide (CO2) and can also produce nitrous oxide (N2O), a greenhouse gas. We interrogated the growth, physiological, and transcriptome responses of N. europaea to conditions of replete (>5.2 mM) and limited inorganic carbon (IC) provided by either 1.0 mM or 0.2 mM sodium carbonate (Na2CO3) supplemented with atmospheric CO2 IC-limited cultures oxidized 25 to 58% of available NH3 to nitrite, depending on the dilution rate and Na2CO3 concentration. IC limitation resulted in a 2.3-fold increase in cellular maintenance energy requirements compared to those for NH3-limited cultures. Rates of N2O production increased 2.5- and 6.3-fold under the two IC-limited conditions, increasing the percentage of oxidized NH3-N that was transformed to N2O-N from 0.5% (replete) up to 4.4% (0.2 mM Na2CO3). Transcriptome analysis showed differential expression (P ≤ 0.05) of 488 genes (20% of inventory) between replete and IC-limited conditions, but few differences were detected between the two IC-limiting treatments. IC-limited conditions resulted in a decreased expression of ammonium/ammonia transporter and ammonia monooxygenase subunits and increased the expression of genes involved in C1 metabolism, including the genes for RuBisCO (cbb gene cluster), carbonic anhydrase, folate-linked metabolism of C1 moieties, and putative C salvage due to oxygenase activity of RuBisCO. Increased expression of nitrite reductase (gene cluster NE0924 to NE0927) correlated with increased production of N2O. Together, these data suggest that N. europaea adapts physiologically during IC-limited steady-state growth, which leads to the uncoupling of NH3 oxidation from growth and increased N2O production. Nitrification, the aerobic oxidation of ammonia to nitrate via nitrite, is an important process in the global nitrogen cycle. This process is generally dependent on ammonia-oxidizing

  13. Resolving surface chemical states in XPS analysis of first row transition metals, oxides and hydroxides: Sc, Ti, V, Cu and Zn

    International Nuclear Information System (INIS)

    Biesinger, Mark C.; Lau, Leo W.M.; Gerson, Andrea R.; Smart, Roger St.C.

    2010-01-01

    Chemical state X-ray photoelectron spectroscopic analysis of first row transition metals and their oxides and hydroxides is challenging due to the complexity of the 2p spectra resulting from peak asymmetries, complex multiplet splitting, shake-up and plasmon loss structure, and uncertain, overlapping binding energies. A review of current literature shows that all values necessary for reproducible, quantitative chemical state analysis are usually not provided. This paper reports a more consistent, practical and effective approach to curve-fitting the various chemical states in a variety of Sc, Ti, V, Cu and Zn metals, oxides and hydroxides. The curve-fitting procedures proposed are based on a combination of (1) standard spectra from quality reference samples, (2) a survey of appropriate literature databases and/or a compilation of the literature references, and (3) specific literature references where fitting procedures are available. Binding energies, full-width at half maximum (FWHM) values, spin-orbit splitting values, asymmetric peak-shape fitting parameters, and, for Cu and Zn, Auger parameters values are presented. The quantification procedure for Cu species details the use of the shake-up satellites for Cu(II)-containing compounds and the exact binding energies of the Cu(0) and Cu(I) peaks. The use of the modified Auger parameter for Cu and Zn species allows for corroborating evidence when there is uncertainty in the binding energy assignment. These procedures can remove uncertainties in analysis of surface states in nano-particles, corrosion, catalysis and surface-engineered materials.

  14. Resolving surface chemical states in XPS analysis of first row transition metals, oxides and hydroxides: Sc, Ti, V, Cu and Zn

    Energy Technology Data Exchange (ETDEWEB)

    Biesinger, Mark C., E-mail: biesingr@uwo.ca [Surface Science Western, University of Western Ontario, University of Western Ontario Research Park, Room LL31, 999 Collip Circle, London, Ontario, N6G 0J3 (Canada); ACeSSS (Applied Centre for Structural and Synchrotron Studies), University of South Australia, Mawson Lakes, SA 5095 (Australia); Lau, Leo W.M. [Surface Science Western, University of Western Ontario, University of Western Ontario Research Park, Room LL31, 999 Collip Circle, London, Ontario, N6G 0J3 (Canada); Department of Chemistry, University of Western Ontario, London, Ontario, N6A 5B7 (Canada); Gerson, Andrea R.; Smart, Roger St.C. [ACeSSS (Applied Centre for Structural and Synchrotron Studies), University of South Australia, Mawson Lakes, SA 5095 (Australia)

    2010-11-15

    Chemical state X-ray photoelectron spectroscopic analysis of first row transition metals and their oxides and hydroxides is challenging due to the complexity of the 2p spectra resulting from peak asymmetries, complex multiplet splitting, shake-up and plasmon loss structure, and uncertain, overlapping binding energies. A review of current literature shows that all values necessary for reproducible, quantitative chemical state analysis are usually not provided. This paper reports a more consistent, practical and effective approach to curve-fitting the various chemical states in a variety of Sc, Ti, V, Cu and Zn metals, oxides and hydroxides. The curve-fitting procedures proposed are based on a combination of (1) standard spectra from quality reference samples, (2) a survey of appropriate literature databases and/or a compilation of the literature references, and (3) specific literature references where fitting procedures are available. Binding energies, full-width at half maximum (FWHM) values, spin-orbit splitting values, asymmetric peak-shape fitting parameters, and, for Cu and Zn, Auger parameters values are presented. The quantification procedure for Cu species details the use of the shake-up satellites for Cu(II)-containing compounds and the exact binding energies of the Cu(0) and Cu(I) peaks. The use of the modified Auger parameter for Cu and Zn species allows for corroborating evidence when there is uncertainty in the binding energy assignment. These procedures can remove uncertainties in analysis of surface states in nano-particles, corrosion, catalysis and surface-engineered materials.

  15. Cyclooxygenase 2 and neuronal nitric oxide synthase expression in the renal cortex are not interdependent in states of salt deficiency

    DEFF Research Database (Denmark)

    Castrop, H; Kammerl, M; Mann, Birgitte

    2000-01-01

    Neuronal nitric oxide synthase (nNOS) and cyclooxygenase-2 (COX-2) expression in the kidney are localized to the cortical thick ascending limb of the loop of Henle (cTALH), including the macula region, and increase after salt restriction. Because of the similar localization and regulation of n...... excretion. These findings suggest that under these conditions the control of nNOS and COX-2 gene expression in the macula densa regions of the kidney cortex are not dependent on each other....

  16. Vacuum-Assisted Low-Temperature Synthesis of Reduced Graphene Oxide Thin-Film Electrodes for High-Performance Transparent and Flexible All-Solid-State Supercapacitors.

    Science.gov (United States)

    Aytug, Tolga; Rager, Matthew S; Higgins, Wesley; Brown, Forrest G; Veith, Gabriel M; Rouleau, Christopher M; Wang, Hui; Hood, Zachary D; Mahurin, Shannon M; Mayes, Richard T; Joshi, Pooran C; Kuruganti, Teja

    2018-04-04

    Simple and easily integrated design of flexible and transparent electrode materials affixed to polymer-based substrates hold great promise to have a revolutionary impact on the functionality and performance of energy storage devices for many future consumer electronics. Among these applications are touch sensors, roll-up displays, photovoltaic cells, health monitors, wireless sensors, and wearable communication devices. Here, we report an environmentally friendly, simple, and versatile approach to produce optically transparent and mechanically flexible all-solid-state supercapacitor devices. These supercapacitors were constructed on tin-doped indium oxide coated polyethylene terephthalate substrates by intercalation of a polymer-based gel electrolyte between two reduced graphene oxide (rGO) thin-film electrodes. The rGO electrodes were fabricated simply by drop-casting of graphene oxide (GO) films, followed by a novel low-temperature (≤250 °C) vacuum-assisted annealing approach for the in situ reduction of GO to rGO. A trade-off between the optical transparency and electrochemical performance is determined by the concentration of the GO in the initial dispersion, whereby the highest capacitance (∼650 μF cm -2 ) occurs at a relatively lower optical transmittance (24%). Notably, the all-solid-state supercapacitors demonstrated excellent mechanical flexibility with a capacity retention rate above 90% under various bending angles and cycles. These attributes underscore the potential of the present approach to provide a path toward the realization of thin-film-based supercapacitors as flexible and transparent energy storage devices for a variety of practical applications.

  17. Reversal magnetization dependence with the Cr and Fe oxidation states in YFe1-xCrxO3 (0≤x≤1) perovskites

    Science.gov (United States)

    Fabian, F. A.; Pedra, P. P.; Moura, K. O.; Duque, J. G. S.; Meneses, C. T.

    2016-06-01

    In this work, we have carried out a detailed study of the magnetic and structural properties of YFe1-xCrxO3 (0≤x≤1) samples with orthorhombic structure obtained by co-precipitation method. Analysis of X-ray diffraction data using Rietveld refinement show that all samples present an orthorhombic crystal system with space group Pnma. Besides, we have observed a reduction of unit cell volume with increasing of the Cr concentration. SEM images show the formation of grains of micrometer order. X-ray Absorption near edge spectroscopy (XANES) measurements show a shift of absorption edge which can be indicate there is (i) different oxidation states to Fe and Cr ions and/or (ii) a changing in the point symmetry of Fe and Cr ions to the compounds. The magnetization measurements indicate a continuous decreasing of the magnetic transition temperature as function of chromium doping. The reversal magnetization effect was observed to concentrations around x=0.5. Besides, the deviation of the Curie-Weiss law and a weak ferromagnetic behavior observed at room temperature in the M vs H curves can be attributed to the strong magnetic interactions between the transition metals with different oxidation states.

  18. Materials space of solid-state electrolytes: unraveling chemical composition-structure-ionic conductivity relationships in garnet-type metal oxides using cheminformatics virtual screening approaches.

    Science.gov (United States)

    Kireeva, Natalia; Pervov, Vladislav S

    2017-08-09

    The organic electrolytes of most current commercial rechargeable Li-ion batteries (LiBs) are flammable, toxic, and have limited electrochemical energy windows. All-solid-state battery technology promises improved safety, cycling performance, electrochemical stability, and possibility of device miniaturization and enables a number of breakthrough technologies towards the development of new high power and energy density microbatteries for electronics with low processing cost, solid oxide fuel cells, electrochromic devices, etc. Currently, rational materials design is attracting significant attention, which has resulted in a strong demand for methodologies that can accelerate the design of materials with tailored properties; cheminformatics can be considered as an efficient tool in this respect. This study was focused on several aspects: (i) identification of the parameters responsible for high Li-ion conductivity in garnet structured oxides; (ii) development of quantitative models to elucidate composition-structure-Li ionic conductivity relationships, taking into account the experimental details of sample preparation; (iii) circumscription of the materials space of solid garnet-type electrolytes, which is attractive for virtual screening. Several candidate compounds have been recommended for synthesis as potential solid state electrolyte materials.

  19. Trichloroethylene and Its Oxidative Metabolites Enhance the Activated State and Th1 Cytokine Gene Expression in Jurkat Cells.

    Science.gov (United States)

    Pan, Yao; Wei, Xuetao; Hao, Weidong

    2015-08-28

    Trichloroethylene (TCE) is an occupational and ubiquitous environmental contaminant, and TCE exposure will increase the risk of autoimmune diseases and allergic diseases. T cells play an important role in the pathogenesis of TCE-related immune disorders, but the effect of TCE and its oxidative metabolites, trichloroacetic acid (TCA) and dichloroacetic acid (DCA), on the activation of human T cells is still unknown. In this study, Jurkat cells were pre-treated with TCE, TCA and DCA overnight and then stimulated with phorbol 12-myristate 13-acetate and ionomycin for another 4, 8 and 24 hours. IL-2 secretion was detected by ELISA; the expressions of CD25 and CD69 were tested by flow cytometry; and IFN-γ and IL-2 mRNA expression levels were investigated by real-time PCR. The results showed that TCE and its oxidative metabolites, TCA and DCA, significantly enhanced IL-2 releasing and the expression of T cell activation markers, CD25 and CD69. Consistent with this result, these compounds markedly up-regulated the expression levels of IFN-γ and IL-2 mRNA. Collectively, these findings suggest that TCE and its metabolites, TCA and DCA, might enhance the activation of T cells and disrupt various activities of peripheral T cells.

  20. Trichloroethylene and Its Oxidative Metabolites Enhance the Activated State and Th1 Cytokine Gene Expression in Jurkat Cells

    Directory of Open Access Journals (Sweden)

    Yao Pan

    2015-08-01

    Full Text Available Trichloroethylene (TCE is an occupational and ubiquitous environmental contaminant, and TCE exposure will increase the risk of autoimmune diseases and allergic diseases. T cells play an important role in the pathogenesis of TCE-related immune disorders, but the effect of TCE and its oxidative metabolites, trichloroacetic acid (TCA and dichloroacetic acid (DCA, on the activation of human T cells is still unknown. In this study, Jurkat cells were pre-treated with TCE, TCA and DCA overnight and then stimulated with phorbol 12-myristate 13-acetate and ionomycin for another 4, 8 and 24 hours. IL-2 secretion was detected by ELISA; the expressions of CD25 and CD69 were tested by flow cytometry; and IFN-γ and IL-2 mRNA expression levels were investigated by real-time PCR. The results showed that TCE and its oxidative metabolites, TCA and DCA, significantly enhanced IL-2 releasing and the expression of T cell activation markers, CD25 and CD69. Consistent with this result, these compounds markedly up-regulated the expression levels of IFN-γ and IL-2 mRNA. Collectively, these findings suggest that TCE and its metabolites, TCA and DCA, might enhance the activation of T cells and disrupt various activities of peripheral T cells.

  1. A phosphate-dependent shift in redox state of cerium oxide nanoparticles and its effects on catalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Sanjay; Dosani, Talib; Karakoti, Ajay S.; Kumar, Amit; Seal, Sudipta; Self, William

    2011-10-01

    Cerium oxide nanoparticles (CeNPs) have shown promise as catalytic antioxidants in cell culture and animal models as both superoxide dismutase and catalase mimetics. The reactivity of the cerium (Ce) atoms at the surface of its oxide particle is critical to such therapeutic properties, yet little is known about the potential for a protein or small molecule corona to form on these materials in vivo. Moreover Ce atoms in these active sites have the potential to interact with small molecule anions, peptides, or sugars when administered in culture or animal models. Several nanomaterials have been shown to alter or aggregate under these conditions, rendering them less useful for biomedical applications. In this work we have studied the change in catalytic properties of CeNPs when exposed to various biologically relevant conditions in vitro. We have found that CeNPs are resistant to broad changes in pH and also not altered by incubation in cell culture medium. However to our surprise phosphate anions significantly altered the characteristics of these nanomaterials and shifted the catalytic behavior due to the binding of phosphate anions to cerium. Given the abundance of phosphate in biological systems in an inorganic form, it is likely that the action of CeNPs as a catalyst may be strongly influenced by the local concentration of phosphate in the cells and/or tissues in which it has been introduced.

  2. Coadministration of Resveratrol and Rice Oil Mitigates Nociception and Oxidative State in a Mouse Fibromyalgia-Like Model

    Directory of Open Access Journals (Sweden)

    Caroline Peres Klein

    2016-01-01

    Full Text Available The mechanism underlying pain symptoms in fibromyalgia (FM is not fully understood. Oxidative stress has emerged as pathophysiological event occurring during the development of the disease. The present study aimed at investigating the efficacy of resveratrol associated with rice bran oil on fibromyalgia-like mice model. Subcutaneous injection of reserpine (0.25 mg/Kg during 3 days produced fibromyalgia-like symptoms. Resveratrol and/or rice oil or pregabalin were administered through oral route in therapeutic (single dose and preventive (four doses schemes. In both schemes, treatment with resveratrol associated with rice bran oil and pregabalin significantly reduced mechanical allodynia and thermal hyperalgesia in animals. The preventive scheme displayed antidepressant effect which was demonstrated by the forced swimming test as well as reduced reactive species in the cerebrospinal fluid of reserpinized animals. Taken together, our data provide evidences that the intake of resveratrol associated with rice bran oil plays antinociceptive and antidepressant actions probably through reducing reactive species and suggests the involvement of oxidative stress in this model of FM as possible underlying mechanism of pathogenesis of the disease.

  3. Atom states and interatomic interactions in complex perovskite-like oxides. 4. Spin state of nickel(2) atoms in LaCa0.5Sr0.5NixAl1-xO4 solid solutions

    International Nuclear Information System (INIS)

    Chezhina, N.V.; Kuznetsova, I.V.

    1995-01-01

    Solid solutions of LaCa 0.5 Sr 0.5 Ni x Al 1-x O 4 (0≤x≤0.10) have been synthesized and their magnetic susceptibility in the temperature range of 77-400 K has been studied. The change in the basic state of nickel atoms in case of partial substitution of calcium for strontium atoms has been studied. The change in the basic state of nickel atoms in case of partial substitution of calcium for strontium atoms has been studied, as well as the way it affects exchange interaction in a complex oxide. It is shown that the substitution results in increase of the degree of paramagnetic atoms aggregation in solid solution. 9 refs., 2 figs., 1 tab

  4. Analysis of interfacial energy states in Au/pentacene/polyimide/indium-zinc-oxide diodes by electroluminescence spectroscopy and electric-field-induced optical second-harmonic generation measurement

    Science.gov (United States)

    Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa

    2016-03-01

    By using electroluminescence (EL) spectroscopy and electric-field-induced optical second-harmonic generation (EFISHG) measurement, we analyzed interfacial energy states in Au/pentacene/polyimide/indium-zinc-oxide (IZO) diodes, to characterize the pentacene/polyimide interface. Under positive voltage application to the Au electrode with reference to the IZO electrode, the EFISHG showed that holes are injected from Au electrode, and accumulate at the pentacene/polyimide interface with the surface charge density of Qs = 3.8 × 10-7 C/cm2. The EL spectra suggested that the accumulated holes are not merely located in the pentacene but they are transferred to the interface states of polyimide. These accumulated holes distribute with the interface state density greater than 1012 cm-2 eV-1 in the range E = 1.5-1.8 and 1.7-2.4 eV in pentacene and in polyimide, respectively, under assumption that accumulated holes govern recombination radiation. The EL-EFISHG measurement is helpful to characterize organic-organic layer interfaces in organic devices and provides a way to analyze interface energy states.

  5. Oxidative stress

    Directory of Open Access Journals (Sweden)

    Osredkar Joško

    2012-05-01

    Full Text Available The human organism is exposed to the influence of various forms of stress, either physical, psychological or chemical, which all have in common that they may adversely affect our body. A certain amount of stress is always present and somehow directs, promotes or inhibits the functioning of the human body. Unfortunately, we are now too many and too often exposed to excessive stress, which certainly has adverse consequences. This is especially true for a particular type of stress, called oxidative stress. All aerobic organisms are exposed to this type of stress because they produce energy by using oxygen. For this type of stress you could say that it is rather imperceptibly involved in our lives, as it becomes apparent only at the outbreak of certain diseases. Today we are well aware of the adverse impact of radicals, whose surplus is the main cause of oxidative stress. However, the key problem remains the detection of oxidative stress, which would allow us to undertake timely action and prevent outbreak of many diseases of our time. There are many factors that promote oxidative stress, among them are certainly a fast lifestyle and environmental pollution. The increase in oxidative stress can also trigger intense physical activity that is directly associated with an increased oxygen consumption and the resulting formation of free radicals. Considering generally positive attitude to physical activity, this fact may seem at first glance contradictory, but the finding has been confimed by several studies in active athletes. Training of a top athlete daily demands great physical effort, which is also reflected in the oxidative state of the organism. However, it should be noted that the top athletes in comparison with normal individuals have a different defense system, which can counteract the negative effects of oxidative stress. Quite the opposite is true for irregular or excessive physical activity to which the body is not adapted.

  6. Development of Lithium Stuffed Garnet-Type Oxide Solid Electrolytes with High Ionic Conductivity for Application to All-Solid-State Batteries

    Directory of Open Access Journals (Sweden)

    Ryoji Inada

    2016-07-01

    Full Text Available All-solid-state lithium-ion battery (LiB is expected as one of the next generation energy storage devices because of their high energy density, high safety and excellent cycle stability. Although oxide-based solid electrolyte materials have rather lower conductivity and poor deformability than sulfide-based one, they have other advantages such as their chemical stability and easiness for handling. Among the various oxide-based SEs, lithium stuffed garnet-type oxide with the formula of Li7La3Zr2O12 (LLZ have been widely studied because of their high conductivity above 10-4 Scm-1 at room temperature, excellent thermal performance and stability against Li metal anode.Here, we present our recent progress for the development of garnet-type solid electrolytes with high conductivity by simultaneous substitution of Ta5+ into Zr4+ site and Ba2+ into La3+ site in LLZ. Li+ concentration was fixed to 6.5 per chemical formulae, so that the formulae of our Li garnet-type oxide is expressed as Li6.5La3-xBaxZr1.5-xTa0.5+xO12 (LLBZT and Ba contents x are changed from 0 to 0.3. As results, all LLBZT samples have cubic garnet structure without containing any secondary phases. The lattice parameters of LLBZT decrease with increasing Ba2+ contents x < 0.10 while increase with x from 0.10 to 0.30, possibly due to the simultaneous change of Ba2+ and Ta5+ substitution levels. Relative densities of LLBZT are in the range between 89% and 93% and not influenced so much by the compositions. From AC impedance spectroscopy measurements, the total (bulk + grain conductivity at 27ºC of LLBZT shows its maximum value of 8.34 x 10-4 S cm-1 at x = 0.10, which is slightly higher than the conductivity (= 7.94 x 10-4 S cm-1 of LLZT without substituting Ba (x = 0. Activation energy of the conductivity tends to become lower by Ba substation, while excess Ba substitution degrades the conductivity in LLBZT. LLBZT has wide electrochemical potential window of 0-6 V vs. Li+/Li and

  7. Detection of different oxidation states of individual manganese porphyrins during their reaction with oxygen at a solid/liquid interface.

    Science.gov (United States)

    den Boer, Duncan; Li, Min; Habets, Thomas; Iavicoli, Patrizia; Rowan, Alan E; Nolte, Roeland J M; Speller, Sylvia; Amabilino, David B; De Feyter, Steven; Elemans, Johannes A A W

    2013-07-01

    Manganese porphyrins have been extensively investigated as model systems for the natural enzyme cytochrome P450 and as synthetic oxidation catalysts. Here, we report single-molecule studies of the multistep reaction of manganese porphyrins with molecular oxygen at a solid/liquid interface, using a scanning tunnelling microscope (STM) under environmental control. The high lateral resolution of the STM, in combination with its sensitivity to subtle differences in the electronic properties of molecules, allowed the detection of at least four distinct reaction species. Real-space and real-time imaging of reaction dynamics enabled the observation of active sites, immobile on the experimental timescale. Conversions between the different species could be tuned by the composition of the atmosphere (argon, air or oxygen) and the surface bias voltage. By means of extensive comparison of the results to those obtained by analogous solution-based chemistry, we assigned the observed species to the starting compound, reaction intermediates and products.

  8. Evaluation of existing United States' facilities for use as a mixed-oxide (MOX) fuel fabrication facility for plutonium disposition

    International Nuclear Information System (INIS)

    Beard, C.A.; Buksa, J.J.; Chidester, K.; Eaton, S.L.; Motley, F.E.; Siebe, D.A.

    1995-01-01

    A number of existing US facilities were evaluated for use as a mixed-oxide fuel fabrication facility for plutonium disposition. These facilities include the Fuels Material Examination Facility (FMEF) at Hanford, the Washington Power Supply Unit 1 (WNP-1) facility at Hanford, the Barnwell Nuclear Fuel Plant (BNFP) at Barnwell, SC, the Fuel Processing Facility (FPF) at Idaho National Engineering Laboratory (INEL), the Device Assembly Facility (DAF) at the Nevada Test Site (NTS), and the P-reactor at the Savannah River Site (SRS). The study consisted of evaluating each facility in terms of available process space, available building support systems (i.e., HVAC, security systems, existing process equipment, etc.), available regional infrastructure (i.e., emergency response teams, protective force teams, available transportation routes, etc.), and ability to integrate the MOX fabrication process into the facility in an operationally-sound manner that requires a minimum amount of structural modifications

  9. Resonance Raman study on photoreduction of cytochrome c oxidase: distinction of cytochromes a and a3 in the intermediate oxidation states.

    Science.gov (United States)

    Ogura, T; Yoshikawa, S; Kitagawa, T

    1985-12-17

    Occurrence of photoreduction of bovine cytochrome c oxidase was confirmed with the difference absorption spectra and oxygen consumption measurements for the enzyme irradiated with laser light at 406.7, 441.6, and 590 nm. The resonance Raman spectra were obtained under the same experimental conditions as those adopted for the measurements of oxygen consumption and difference absorption spectra. The photoreduction was more effective upon irradiation at shorter wavelengths and was irreversible under anaerobic conditions. However, upon aeration into the cell, the original oxidized form was restored. It was found that aerobic laser irradiation produces a photo steady state of the catalytic dioxygen reduction and that the Raman scattering from this photo steady state probes cytochrome a2+ and cytochrome a3(3)+ separately upon excitations at 441.6 and 406.7 nm, respectively. The enzyme was apparently protected from the photoreduction in the spinning cell with the spinning speed between 1 and 1500 rpm. These results were explained satisfactorily with the reported rate constant for the electron transfer from cytochrome a to cytochrome a3 (0.58 s-1) and a comparable photoreduction rate of cytochrome a. The anaerobic photoreduction did give Raman lines at 1666 and 214 cm-1, which are characteristic of the ferrous high-spin cytochrome a3(2)+, but they were absent under aerobic photoreduction. The formyl CH = O stretching mode of the a3 heme was observed at 1671 cm-1 for a2+a3(2)+CO but at 1664 cm-1 for a2+a3(2)+CN-, indicating that the CH = O stretching frequency reflects the pi back-donation to the axial ligand similar to the oxidation state marker line (v4).

  10. Investigation of the Reversible Lithiation of an Oxide Free Aluminum Anode by a LiBH4 Solid State Electrolyte

    Directory of Open Access Journals (Sweden)

    Jason A. Weeks

    2017-11-01

    Full Text Available In this study, we analyze and compare the physical and electrochemical properties of an all solid-state cell utilizing LiBH4 as the electrolyte and aluminum as the active anode material. The system was characterized by galvanostatic lithiation/delithiation, cyclic voltammetry (CV, X-ray diffraction (XRD, energy dispersive X-ray spectroscopy (EDS, Raman spectroscopy, electrochemical impedance spectroscopy (EIS, and scanning electron microscopy (SEM. Constant current cycling demonstrated that the aluminum anode can be reversibly lithiated over multiple cycles utilizing a solid-state electrolyte. An initial capacity of 895 mAh/g was observed and is close to the theoretical capacity of aluminum. Cyclic voltammetry of the cell was consistent with the constant current cycling data and showed that the reversible lithiation/delithiation of aluminum occurs at 0.32 V and 0.38 V (vs. Li+/Li respectively. XRD of the aluminum anode in the initial and lithiated state clearly showed the formation of a LiAl (1:1 alloy. SEM-EDS was utilized to examine the morphological changes that occur within the electrode during cycling. This work is the first example of reversible lithiation of aluminum in a solid-state cell and further emphasizes the robust nature of the LiBH4 electrolyte. This demonstrates the possibility of utilizing other high capacity anode materials with a LiBH4 based solid electrolyte in all-solid-state batteries.

  11. Observation of high-spin mixed oxidation state of cobalt in ceramic Co3TeO6

    Science.gov (United States)

    Singh, Harishchandra; Ghosh, Haranath; Chandrasekhar Rao, T. V.; Sinha, A. K.; Rajput, Parasmani

    2014-12-01

    We report coexistence of high spin Co3+ and Co2+ in ceramic Co3TeO6 using X-ray Absorption Near Edge Structure (XANES), DC magnetization, and first principles ab-initio calculations. The main absorption line of cobalt Co K-edge XANES spectra, along with a linear combination fit, led us to estimate relative concentration of Co2+ and Co3+as 60:40. The pre edge feature of XANES spectrum shows crystal field splitting of ˜1.26 eV between eg and t2g states, suggesting a mixture of high spin states of both Co2+ and Co3+. Temperature dependent high field DC magnetization measurements reveal dominant antiferromagnetic order with two Neel temperatures (TN1 ˜ 29 K and TN2 ˜ 18 K), consistent with single crystal study. A larger effective magnetic moment is observed in comparison to that reported for single crystal (which contains only Co2+), supports our inference that Co3+ exists in high spin state. Furthermore, we show that both Co2+ and Co3+ being in high spin states constitute a favorable ground state through first principles ab-initio calculations, where Rietveld refined synchrotron X-ray diffraction data are used as input.

  12. Position Assignment and Oxidation State Recognition of Fe and Co Centers in Heterometallic Mixed-Valent Molecular Precursors for the Low-Temperature Preparation of Target Spinel Oxide Materials

    Energy Technology Data Exchange (ETDEWEB)

    Lieberman, Craig M. [Department of Chemistry, University at Albany, Albany, New York 12222, United States; Barry, Matthew C. [Department of Chemistry, University at Albany, Albany, New York 12222, United States; Wei, Zheng [Department of Chemistry, University at Albany, Albany, New York 12222, United States; Rogachev, Andrey Yu. [Department; Wang, Xiaoping [Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States; Liu, Jun-Liang [CNRS, CRPP, UPR 8641, F-33600 Pessac, France; Univ. Bordeaux, UPR 8641, F-33600 Pessac, France; MOE Key Lab of Bioinorganic and Synthetic Chemistry,; Clérac, Rodolphe [CNRS, CRPP, UPR 8641, F-33600 Pessac, France; Univ. Bordeaux, UPR 8641, F-33600 Pessac, France; Chen, Yu-Sheng [ChemMatCARS, Center for Advanced Radiation; Filatov, Alexander S. [Department; Dikarev, Evgeny V. [Department of Chemistry, University at Albany, Albany, New York 12222, United States

    2017-07-31

    A series of mixed-valent, heterometallic (mixed-transition metal) diketonates that can be utilized as prospective volatile single-source precursors for the low-temperature preparation of MxM'3–xO4 spinel oxide materials is reported. Three iron–cobalt complexes with Fe/Co ratios of 1:1, 1:2, and 2:1 were synthesized by several methods using both solid-state and solution reactions. On the basis of nearly quantitative reaction yields, elemental analyses, and comparison of metal–oxygen bonds with those in homometallic analogues, heterometallic compounds were formulated as [FeIII(acac)3][CoII(hfac)2] (1), [CoII(hfac)2][FeIII(acac)3][CoII(hfac)2] (2), and [FeII(hfac)2][FeIII(acac)3][CoII(hfac)2] (3). In the above heteroleptic complexes, the Lewis acidic, coordinatively unsaturated CoII/FeII centers chelated by two hexafluoroacetylacetonate (hfac) ligands maintain bridging interactions with oxygen atoms of acetylacetonate (acac) groups that chelate the neighboring FeIII metal ion. Preliminary assignment of Fe and Co positions/oxidation states in 1–3 drawn from X-ray structural investigation was corroborated by a number of complementary techniques. Single-crystal resonant synchrotron diffraction and neutron diffraction experiments unambiguously confirmed the location of Fe and Co sites in the molecules of dinuclear (1) and trinuclear (2) complexes, respectively. Direct analysis in real time mass spectrometry revealed the presence of FeIII- and CoII-based fragments in the gas phase upon evaporation of precursors 1 and 2 as well as of FeIII, FeII, and CoII species for complex 3. Theoretical investigation of two possible “valent isomers”, [FeIII(acac)3

  13. Ebselen impairs cellular oxidative state and induces endoplasmic reticulum stress and activation of crucial mitogen-activated protein kinases in pancreatic tumour AR42J cells.

    Science.gov (United States)

    Santofimia-Castaño, Patricia; Izquierdo-Alvarez, Alicia; Plaza-Davila, María; Martinez-Ruiz, Antonio; Fernandez-Bermejo, Miguel; Mateos-Rodriguez, Jose M; Salido, Gines M; Gonzalez, Antonio

    2018-01-01

    Ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-one) is an organoselenium radical scavenger compound, which has strong antioxidant and anti-inflammatory effects. However, evidence suggests that this compound could exert deleterious actions on cell physiology. In this study, we have analyzed the effect of ebselen on rat pancreatic AR42J cells. Cytosolic free-Ca 2+ concentration ([Ca 2+ ] c ), cellular oxidative status, setting of endoplasmic reticulum stress, and phosphorylation of major mitogen-activated protein kinases were analyzed. Our results show that ebselen evoked a concentration-dependent increase in [Ca 2+ ] c . The compound induced an increase in the generation of reactive oxygen species in the mitochondria. We also observed an increase in global cysteine oxidation in the presence of ebselen. In the presence of ebselen an impairment of cholecystokinin-evoked amylase release was noted. Moreover, involvement of the unfolded protein response markers, ER chaperone and signaling regulator GRP78/BiP, eukaryotic translation initiation factor 2α and X-box binding protein 1 was detected. Finally, increases in the phosphorylation of SAPK/JNK, p38 MAPK, and p44/42 MAPK in the presence of ebselen were also observed. Our results provide evidences for an impairment of cellular oxidative state and enzyme secretion, the induction of endoplasmic reticulum stress and the activation of crucial mitogen-activated protein kinases in the presence of ebselen. As a consequence ebselen exerts a potential toxic effect on AR42J cells. © 2017 Wiley Periodicals, Inc.

  14. Attestation in self-propagating combustion approach of spinel AFe_2O_4 (A = Co, Mg and Mn) complexes bearing mixed oxidation states: Magnetostructural properties

    International Nuclear Information System (INIS)

    Bennet, J.; Tholkappiyan, R.; Vishista, K.; Jaya, N. Victor; Hamed, Fathalla

    2016-01-01

    Highlights: • Spinel type ferrite compounds AFe_2O_4 (A = Co, Mg and Mn) have been successfully prepared by self-propagating combustion method using glycine as fuel. • To investigate and confirms the presence of phases in the synthesized ferrite nanoparticles by XRD and FTIR analysis. • The formation of mixed oxidation state of cobalt (Co"2"+ and Co"3"+), iron (Fe"2"+ and Fe"3"+) and manganese (Mn"2"+ and Mn"3"+) ions were studied and confirmed from XPS analysis. • The magnetic properties of the synthesized ferrites were studied by VSM measurement. - Abstract: Spinel type nano-sized ferrite compounds AFe_2O_4 (A = Co, Mg and Mn) have been successfully prepared by self-propagating combustion method using glycine as fuel at 400 °C under air atmosphere for 4 h. The crystal structure, chemical composition, morphology and magnetic properties of the synthesized samples were characterized by X−ray diffraction, Fourier transform infrared spectroscopy, X−ray photoelectron spectroscopy, Energy dispersive X−ray, Scanning and Transmission electron microscopy and vibrating sample magnetometer. The chemical reaction and role of fuel on the nanoparticles formation were discussed. The XRD pattern of the synthesized samples shows the formation of pure phase with average crystallite size of 97, 57 and 98 nm from Scherrer formula and 86, 54 and 87 nm from Williamson and Hall (W–H) formula respectively. FTIR absorption spectra revealed that the presence of strong absorption peaks near 400–600 cm"−"1 corresponds to tetrahedral and octahedral complex of spinel ferrites. The relative concentrations of electronic states of elements such as cobalt (Co"2"+ and Co"3"+), iron (Fe"2"+ and Fe"3"+) and manganese (Mn"2"+ and Mn"3"+) oxidation states were studied from XPS and it is found that 55% of Fe ions are in Fe"2"+ state and the remaining is in Fe"3"+ state and thus the cationic distribution of Fe ions occurred in both tetrahedral and octahedral sites. SEM analysis

  15. Thermoelectric Properties of the Perovskite-Type Oxide SrTi1-xNbxO3 Synthesized by Solid-State Reaction Method

    Science.gov (United States)

    Khan, Tamal Tahsin; Ur, Soon-Chul

    2018-05-01

    The perovskite-type oxide materials SrTi1-xNbxO3 (X = .02, 0.03, 0.04, 0.05 and 0.06) were synthesized by the conventional solid-state reaction method and the thermoelectric properties in terms of Nb doping at the B-site in the oxides were investigated in this study. The formation of single phase cubic perovskite structure was confirmed by the powder X-ray diffraction analysis. Negative conduction is shown in this materials system. The absolute value of Seebeck coefficient increased with increasing temperature over the measured temperature. The electrical conductivity decreased monotonically with increasing temperature, showing degenerating conduction behavior. The thermal conductivity, k, generally decreased with increasing temperature. The power factor increased with increasing Nb-doping level up to 5.0 mol% and hence the dimensionless figure of merit ZT, increased up to 5.0 mol%. The maximum ZT value was observed for SrTi0.95Nb0.05O3 at 873 K.

  16. Survival or revival: long-term preservation induces a reversible viable but non-culturable state in methane-oxidizing bacteria.

    Directory of Open Access Journals (Sweden)

    Sven Hoefman

    Full Text Available Knowledge on long-term preservation of micro-organisms is limited and research in the field is scarce despite its importance for microbial biodiversity and biotechnological innovation. Preservation of fastidious organisms such as methane-oxidizing bacteria (MOB has proven difficult. Most MOB do not survive lyophilization and only some can be cryopreserved successfully for short periods. A large-scale study was designed for a diverse set of MOB applying fifteen cryopreservation or lyophilization conditions. After three, six and twelve months of preservation, the viability (via live-dead flow cytometry and culturability (via most-probable number analysis and plating of the cells were assessed. All strains could be cryopreserved without a significant loss in culturability using 1% trehalose in 10-fold diluted TSB (TT as preservation medium and 5% DMSO as cryoprotectant. Several other cryopreservation and lyophilization conditions, all of which involved the use of TT medium, also allowed successful preservation but showed a considerable loss in culturability. We demonstrate here that most of these non-culturables survived preservation according to viability assessment indicating that preservation induces a viable but non-culturable (VBNC state in a significant fraction of cells. Since this state is reversible, these findings have major implications shifting the emphasis from survival to revival of cells in a preservation protocol. We showed that MOB cells could be significantly resuscitated from the VBNC state using the TT preservation medium.

  17. Three-Dimensional Expanded Graphene-Metal Oxide Film via Solid-State Microwave Irradiation for Aqueous Asymmetric Supercapacitors.

    Science.gov (United States)

    Yang, MinHo; Lee, Kyoung G; Lee, Seok Jae; Lee, Sang Bok; Han, Young-Kyu; Choi, Bong Gill

    2015-10-14

    Carbon-based electrochemical double-layer capacitors and pseudocapacitors, consisting of a symmetric configuration of electrodes, can deliver much higher power densities than batteries, but they suffer from low energy densities. Herein, we report the development of high energy and power density supercapacitors using an asymmetric configuration of Fe2O3 and MnO2 nanoparticles incorporated into 3D macroporous graphene film electrodes that can be operated in a safe and low-cost aqueous electrolyte. The gap in working potential windows of Fe2O3 and MnO2 enables the stable expansion of the cell voltage up to 1.8 V, which is responsible for the high energy density (41.7 Wh kg(-1)). We employ a household microwave oven to simultaneously create conductivity, porosity, and the deposition of metal oxides on graphene films toward 3D hybrid architectures, which lead to a high power density (13.5 kW kg(-1)). Such high energy and power densities are maintained for over 5000 cycles, even during cycling at a high current density of 16.9 A g(-1).

  18. The role of MgCl2 compounds in preparation of Tin oxide micro particles by one-step solid - state chemical reaction method and characterization of microstructure

    International Nuclear Information System (INIS)

    Hojabry, A.; Rezainik, Y.; Abdoljavad, N.; Moghimi, N.; Shakib, M.

    2007-01-01

    In this paper, Tin oxide (SnO 2 ) nano crystals have been synthesized by one-step solid-state chemical reactions method. In the first step, the powder of SnCl 4 . 5H 2 O was mixed with MgCl 2 and Mg(OH) 2 with a weight ratio of Sn to Mg (2:1) in the air atmosphere at room, and then annealed at 200 d egree C , 400 d egree C and 600 d egree C in air for 4 h to give different size of nanoparticles. This method is a simple, efficient and economic preparation for SnO 2 nanoparticles with adjustable grain sizes in the range of 7-32 nm in high yield. The microstructure and morphology of SnO 2 nanoparticles have been studied by X-ray diffraction (XRD), scanning electron microscopy and thermal analysis (thermogravimetric analysis -differential thermal analysis).

  19. Influence of physiologically active complex isolated from human amnion on lipid peroxide oxidation state and antioxidant activity of blood in rats after irradiation in different doses

    International Nuclear Information System (INIS)

    Borshchevs'ka, M.Yi.; Popov, V.V.; Abramova, L.P.; Kuz'myinova, Yi.A.

    1995-01-01

    The authors have studied the influence of physiologically active complex isolated from human amnion on the state of lipid peroxide oxidation according to diene conjugate and malonic dialdehyde amount and antioxidant enzyme activity (catalase and glutationperoxidase) in the blood of the rats exposed to single total irradiation in different doses (4 and 6 Gy) was studied. Definite changes of peroxide process intensity and reduction of the enzymes activity were shown to be observed in the blood of experimental animals even at long terms after the radiation exposure. Under the background of radiation exposure, administration of physiologically active complex isolated from human amnion produced protective effect on antioxidant enzyme activity which promoted normalization of peroxidation processes within the post-radiation period

  20. Combination of synchrotron radiation X-ray microprobe and nuclear microprobe for chromium and chromium oxidation states quantitative mapping in single cells

    International Nuclear Information System (INIS)

    Ortega, Richard; Deves, Guillaume; Fayard, Barbara; Salome, Murielle; Susini, Jean

    2003-01-01

    Hexavalent chromium compounds are established carcinogens but their mechanism of cell transformation has not been elucidated yet. In this study, chromium oxidation state distribution maps in cells exposed to soluble (Na 2 CrO 4 ), or insoluble (PbCrO 4 ), Cr(VI) compounds have been obtained by use of the ESRF ID-21 X-ray microscope. In addition, the quantitative maps of element distributions in cells have been determined using the nuclear microprobe of Bordeaux-Gradignan. Nuclear microprobe quantitative analysis revealed interesting features on chromium, and lead, cellular uptake. It is suggested that cells can enhance PbCrO 4 solubility, resulting in chromium, but not lead uptake. The differential carcinogenic potential of soluble and insoluble Cr(VI) compounds is discussed with regard to chromium intracellular quantitative distribution

  1. Manufacture and application of RuO2 solid-state metal-oxide pH sensor to common beverages.

    Science.gov (United States)

    Lonsdale, W; Wajrak, M; Alameh, K

    2018-04-01

    A new reproducible solid-state metal-oxide pH sensor for beverage quality monitoring is developed and characterised. The working electrode of the developed pH sensor is based on the use of laser-etched sputter-deposited RuO 2 on Al 2 O 3 substrate, modified with thin layers of sputter-deposited Ta 2 O 5 and drop-cast Nafion for minimisation of redox interference. The reference electrode is manufactured by further modifying a working electrode with a porous polyvinyl butyral layer loaded with fumed SiO 2 . The developed pH sensor shows excellent performance when applied to a selection of beverage samples, with a measured accuracy within 0.08 pH of a commercial glass pH sensor. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Effects of aging and exercise training on leg hemodynamics and oxidative metabolism in the transition from rest to steady state exercise

    DEFF Research Database (Denmark)

    Piil, Peter Bergmann; Jørgensen, Tue Smith; Egelund, Jon

    2018-01-01

    hemodynamics and oxidative metabolism in the transition from rest to steady state exercise engaging the knee-extensor muscles in young (n=15, 25{plus minus}1 years) and older (n=15, 72{plus minus}1 years) subjects before and after a period of aerobic high-intensity exercise training. To enhance cGMP signaling....... The rate of increase in leg VO2 was, however, similar in the two groups as a result of higher ( PGMP signaling did not affect the rate of increase in blood flow or VO2 in either group. Exercise training augmented ( P.... A lower blood flow response in aging does not appear to be a result of reduced cGMP signaling....

  3. Dual functional rhodium oxide nanocorals enabled sensor for both non-enzymatic glucose and solid-state pH sensing.

    Science.gov (United States)

    Dong, Qiuchen; Huang, Yikun; Song, Donghui; Wu, Huixiang; Cao, Fei; Lei, Yu

    2018-07-30

    Both pH-sensitive and glucose-responsive rhodium oxide nanocorals (Rh 2 O 3 NCs) were synthesized through electrospinning followed by high-temperature calcination. The as-prepared Rh 2 O 3 NCs were systematically characterized using various advanced techniques including scanning electron microscopy, X-ray powder diffraction and Raman spectroscopy, and then employed as a dual functional nanomaterial to fabricate a dual sensor for both non-enzymatic glucose sensing and solid-state pH monitoring. The sensing performance of the Rh 2 O 3 NCs based dual sensor toward pH and glucose was evaluated using open circuit potential, cyclic voltammetry and amperometric techniques, respectively. The results show that the as-prepared Rh 2 O 3 NCs not only maintain accurate and reversible pH sensitivity of Rh 2 O 3 , but also demonstrate a good electrocatalytic activity toward glucose oxidation in alkaline medium with a sensitivity of 11.46 μA mM -1 cm -2 , a limit of detection of 3.1 μM (S/N = 3), and a reasonable selectivity against various interferents in non-enzymatic glucose detection. Its accuracy in determining glucose in human serum samples was further demonstrated. These features indicate that the as-prepared Rh 2 O 3 NCs hold great promise as a dual-functional sensing material in the development of a high-performance sensor forManjakkal both solid-state pH and non-enzymatic glucose sensing. Copyright © 2018 Elsevier B.V. All rights reserved.

  4. The decisive effect of interface states on the photocatalytic activity of the silver(I) oxide/titanium dioxide heterojunction.

    Science.gov (United States)

    Lei, Yanqiang; Lu, Xiaoqing

    2017-04-15

    A one-step hydrothermal method was adopted to synthesize the Ag 2 O/TiO 2 nanoheterojunction. Its photocatalytic activity was evaluated by degrading methylene blue (MB) aqueous solution under UV and visible light. The MB degradation results showed that the Ag 2 O/TiO 2 nanoheterojunction enhances the photocatalytic activity under UV irradiation rather than visible light. X-ray photoelectron spectroscopy (XPS) was performed to detect the electronic structure at the interface of Ag 2 O and TiO 2 . The XPS results confirmed that the electronic band structure of the nanoheterojunction was determined by the interface states between the Ag 2 O and TiO 2 interface. Thus, the photocatalytic enhancement mechanism can be ascribed to the creation of an additional potential barrier in the conduction band between Ag 2 O and TiO 2 , which facilitates the transport of holes from TiO 2 to Ag 2 O but inhibits the flow of electrons in the reverse direction unless sufficient potential energy is provided to overcome the additional barrier. Our results have provided a new insight on the role of interface states between the p-n nanojunction in the photocatalytic activity. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. The electric dipole moments in the ground states of gold oxide, AuO, and gold sulfide, AuS.

    Science.gov (United States)

    Zhang, Ruohan; Yu, Yuanqin; Steimle, Timothy C; Cheng, Lan

    2017-02-14

    The B 2 Σ - - X 2 Π 3/2 (0,0) bands of a cold molecular beam sample of gold monoxide, AuO, and gold monosulfide, AuS, have been recorded at high resolution both field free and in the presence of a static electric field. The observed electric field induced splittings and shifts were analyzed to produce permanent electric dipole moments, μ→ el , of 2.94±0.06 D and 2.22±0.05 D for the X 2 Π 3/2 (v = 0) states of AuO and AuS, respectively. A molecular orbital correlation diagram is used to rationalize the trend in ground state μ→ el values for AuX (X = F, Cl, O, and S) molecules. The experimentally determined μ→ el are compared to those computed at the coupled-cluster singles and doubles (CCSD) level augmented with a perturbative inclusion of triple excitations (CCSD(T)) level of theory.

  6. Radiolytic synthesis of carbon-supported PtRu nanoparticles using high-energy electron beam: effect of pH control on the PtRu mixing state and the methanol oxidation activity

    International Nuclear Information System (INIS)

    Ohkubo, Yuji; Kageyama, Satoru; Seino, Satoshi; Nakagawa, Takashi; Kugai, Junichiro; Nitani, Hiroaki; Ueno, Koji; Yamamoto, Takao A.

    2013-01-01

    Electrode catalysts composed of carbon-supported PtRu nanoparticles (PtRu/C) for use as a direct methanol fuel cell anode were synthesized by the reduction of precursor ions in an aqueous solution via irradiation with a high-energy electron beam. The effect of pH control in the precursor solution on the PtRu mixing state and the methanol oxidation activity was studied in order to enhance the catalytic activity for methanol oxidation. The PtRu/C structures were characterized by transmission electron microscopy, inductively coupled plasma atomic emission spectrometry, X-ray fluorescence spectrometry, and X-ray diffraction and X-ray absorption fine structure techniques. The methanol oxidation activity was evaluated by linear sweep voltammetry. The initial pH of the precursor solution has little influence on the average grain size for the metal particles (approximately 3.5 nm) on the carbon particle supports, but the dispersibility of the metal particles, PtRu mixing state, and methanol oxidation activity differed. The maintenance of a low pH in the precursor solution gave the best dispersibility of the PtRu nanoparticles supported on the surface of the carbon particles, whereas, a high pH gave the best PtRu mixing state and the highest oxidation current although a low dispersibility of the PtRu nanoparticles supported on the surface of the carbon particles was obtained. The PtRu mixing state strongly correlated with the methanol oxidation current. In addition, a high pH was more effective for PtRu mixing when using an electron beam irradiation reduction method, because the complexation reaction of the chelating agents was improved, which resulted in an enhancement of the catalytic activity for methanol oxidation.

  7. Radiolytic synthesis of carbon-supported PtRu nanoparticles using high-energy electron beam: effect of pH control on the PtRu mixing state and the methanol oxidation activity

    Energy Technology Data Exchange (ETDEWEB)

    Ohkubo, Yuji, E-mail: okubo@mit.eng.osaka-u.ac.jp; Kageyama, Satoru; Seino, Satoshi; Nakagawa, Takashi; Kugai, Junichiro [Osaka University, Graduate School of Engineering (Japan); Nitani, Hiroaki [High Energy Accelerator Research Organization (KEK), Institute of Materials Structure Science (Japan); Ueno, Koji [Japan Electron Beam Irradiation Service Ltd (Japan); Yamamoto, Takao A. [Osaka University, Graduate School of Engineering (Japan)

    2013-05-15

    Electrode catalysts composed of carbon-supported PtRu nanoparticles (PtRu/C) for use as a direct methanol fuel cell anode were synthesized by the reduction of precursor ions in an aqueous solution via irradiation with a high-energy electron beam. The effect of pH control in the precursor solution on the PtRu mixing state and the methanol oxidation activity was studied in order to enhance the catalytic activity for methanol oxidation. The PtRu/C structures were characterized by transmission electron microscopy, inductively coupled plasma atomic emission spectrometry, X-ray fluorescence spectrometry, and X-ray diffraction and X-ray absorption fine structure techniques. The methanol oxidation activity was evaluated by linear sweep voltammetry. The initial pH of the precursor solution has little influence on the average grain size for the metal particles (approximately 3.5 nm) on the carbon particle supports, but the dispersibility of the metal particles, PtRu mixing state, and methanol oxidation activity differed. The maintenance of a low pH in the precursor solution gave the best dispersibility of the PtRu nanoparticles supported on the surface of the carbon particles, whereas, a high pH gave the best PtRu mixing state and the highest oxidation current although a low dispersibility of the PtRu nanoparticles supported on the surface of the carbon particles was obtained. The PtRu mixing state strongly correlated with the methanol oxidation current. In addition, a high pH was more effective for PtRu mixing when using an electron beam irradiation reduction method, because the complexation reaction of the chelating agents was improved, which resulted in an enhancement of the catalytic activity for methanol oxidation.

  8. Electrochemical performance of all-solid-state lithium secondary batteries with Li-Ni-Co-Mn oxide positive electrodes

    International Nuclear Information System (INIS)

    Kitaura, Hirokazu; Hayashi, Akitoshi; Tadanaga, Kiyoharu; Tatsumisago, Masahiro

    2010-01-01

    LiNi 1/3 Co 1/3 Mn 1/3 O 2 was applied as a promising material to the all-solid-state lithium cells using the 80Li 2 S.19P 2 S 5 .1P 2 O 5 (mol%) solid electrolyte. The cell showed the first discharge capacity of 115 mAh g -1 at the current density of 0.064 mA cm -2 and retained the reversible capacity of 110 mAh g -1 after 10 cycles. The interfacial resistance was observed in the impedance spectrum of the all-solid-state cell charged to 4.4 V (vs. Li) and the transition metal elements were detected on the solid electrolyte in the vicinity of LiNi 1/3 Co 1/3 Mn 1/3 O 2 by the TEM observations with EDX analyses. The electrochemical performance was improved by the coating of LiNi 1/3 Co 1/3 Mn 1/3 O 2 particles with Li 4 Ti 5 O 12 film. The interfacial resistance was decreased and the discharge capacity was increased from 63 to 83 mAh g -1 at 1.3 mA cm -2 by the coating. The electrochemical performance of LiNi 1/3 Co 1/3 Mn 1/3 O 2 was compared with that of LiCoO 2 , LiMn 2 O 4 and LiNiO 2 in the all-solid-state cells. The rate capability of LiNi 1/3 Co 1/3 Mn 1/3 O 2 was lower than that of LiCoO 2 . However, the reversible capacity of LiNi 1/3 Co 1/3 Mn 1/3 O 2 at 0.064 mA cm -2 was larger than that of LiCoO 2 , LiMn 2 O 4 and LiNiO 2 .

  9. Mapping critical levels of ozone, sulfur dioxide and nitrogen oxide for crops, forests and natural vegetation in the United States

    International Nuclear Information System (INIS)

    Rosenbaum, B.J.; Strickland, T.C.; McDowell, M.K.

    1994-01-01

    Air pollution abatement strategies for controlling nitrogen dioxide, sulfur dioxide, and ozone emissions in the United States focus on a 'standards-based' approach. This approach places limits on air pollution by maintaining a baseline value for air quality, no matter what the ecosystem can or cannot withstand. This paper, presents example critical levels maps for the conterminous U.S. developed using the 'effects-based' mapping approach as defined by the United Nations Economic Commission for Europe's Convention on Long-Range Transboundary Air Pollution, Task Force on Mapping. This approach emphasizes the pollution level or load capacity an ecosystem can accommodate before degradation occurs, and allows for analysis of cumulative effects. Presents the first stage of an analysis that reports the distribution of exceedances of critical levels for NO 2 , SO 2 , and O 3 in sensitive forest, crop, and natural vegetation ecosystems in the contiguous United States. It is concluded that extrapolation to surrounding geographic areas requires the analysis of diverse and compounding factors that preclude simple extrapolation methods. Pollutant data depicted in this analysis are limited to locationally specific data, and would be enhanced by utilizing spatial statistics, along with converging associated anthropogenic and climatological factors. Values used for critical levels were derived from current scientific knowledge. While not intended to be a definitive value, adjustments will occur as the scientific community gains new insight to pollutant/receptor relationships. We recommend future analysis to include a refinement of sensitive receptor data coverages and to report relative proportions of exceedances at varying grid scales. 27 refs., 4 figs., 1 tab

  10. Probing the electronic structures of low oxidation-state uranium fluoride molecules UF{sub x}{sup −} (x = 2−4)

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wei-Li; Jian, Tian; Lopez, Gary V.; Wang, Lai-Sheng, E-mail: lai-sheng-wang@brown.edu [Department of Chemistry, Brown University, Providence, Rhode Island 02912 (United States); Hu, Han-Shi; Li, Jun, E-mail: junli@tsinghua.edu.cn [Department of Chemistry and Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Tsinghua University, Beijing 100084 (China); William R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Su, Jing [Department of Chemistry and Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Tsinghua University, Beijing 100084 (China)

    2013-12-28

    We report the experimental observation of gaseous UF{sub x}{sup −} (x = 2−4) anions, which are investigated using photoelectron spectroscopy and relativistic quantum chemistry. Vibrationally resolved photoelectron spectra are obtained for all three species and the electron affinities of UF{sub x} (x = 2−4) are measured to be 1.16(3), 1.09(3), and 1.58(3) eV, respectively. Significant multi-electron transitions are observed in the photoelectron spectra of U(5f{sup 3}7s{sup 2})F{sub 2}{sup −}, as a result of strong electron correlation effects of the two 7s electrons. The U−F symmetric stretching vibrational modes are resolved for the ground states of all UF{sub x} (x = 2−4) neutrals. Theoretical calculations are performed to qualitatively understand the photoelectron spectra. The entire UF{sub x}{sup −} and UF{sub x} (x = 1−6) series are considered theoretically to examine the trends of U−F bonding and the electron affinities as a function of fluorine coordination. The increased U−F bond lengths and decreased bond orders from UF{sub 2}{sup −} to UF{sub 4}{sup −} indicate that the U−F bonding becomes weaker as the oxidation state of U increases from I to III.

  11. S-containing copolymer as cathode material in poly(ethylene oxide)-based all-solid-state Li-S batteries

    Science.gov (United States)

    Gracia, Ismael; Ben Youcef, Hicham; Judez, Xabier; Oteo, Uxue; Zhang, Heng; Li, Chunmei; Rodriguez-Martinez, Lide M.; Armand, Michel

    2018-06-01

    Inverse vulcanization copolymers (p(S-DVB)) from the radical polymerization of elemental sulfur and divinylbenzene (DVB) have been studied as cathode active materials in poly(ethylene oxide) (PEO)-based all-solid-state Li-S cells. The Li-S cell comprising the optimized p(S-DVB) cathode (80:20 w/w S/DVB ratio) and lithium bis(fluorosulfonyl)imide/PEO (LiFSI/PEO) electrolyte shows high specific capacity (ca. 800 mAh g-1) and high Coulombic efficiency for 50 cycles. Most importantly, polysulfide (PS) shuttle is highly mitigated due to the strong interactions of PS species with polymer backbone in p(S-DVB). This is demonstrated by the stable cycling of the p(S-DVB)-based cell using lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)/PEO electrolyte, where successful charging cannot be achieved even at the first cycle with plain elemental S-based cathode material due to the severe PS shuttle phenomenon. These results suggest that inverse vulcanization copolymers are promising alternatives to elemental sulfur for enhancing the electrochemical performance of PEO-based all-solid-state Li-S cells.

  12. A silicon doped hafnium oxide ferroelectric p–n–p–n SOI tunneling field–effect transistor with steep subthreshold slope and high switching state current ratio

    Directory of Open Access Journals (Sweden)

    Saeid Marjani

    2016-09-01

    Full Text Available In this paper, a silicon–on–insulator (SOI p–n–p–n tunneling field–effect transistor (TFET with a silicon doped hafnium oxide (Si:HfO2 ferroelectric gate stack is proposed and investigated via 2D device simulation with a calibrated nonlocal band–to–band tunneling model. Utilization of Si:HfO2 instead of conventional perovskite ferroelectrics such as lead zirconium titanate (PbZrTiO3 and strontium bismuth tantalate (SrBi2Ta2O9 provides compatibility to the CMOS process as well as improved device scalability. By using Si:HfO2 ferroelectric gate stack, the applied gate voltage is effectively amplified that causes increased electric field at the tunneling junction and reduced tunneling barrier width. Compared with the conventional p–n–p–n SOI TFET, the on–state current and switching state current ratio are appreciably increased; and the average subthreshold slope (SS is effectively reduced. The simulation results of Si:HfO2 ferroelectric p–n–p–n SOI TFET show significant improvement in transconductance (∼9.8X enhancement at high overdrive voltage and average subthreshold slope (∼35% enhancement over nine decades of drain current at room temperature, indicating that this device is a promising candidate to strengthen the performance of p–n–p–n and conventional TFET for a switching performance.

  13. The role of oxidation states in F A1 Tl n+ (n = 1, 3) lasers and CO interactions at the (1 0 0) surface of NaCl: An ab initio study

    International Nuclear Information System (INIS)

    Shalabi, A.S.; Abdel Aal, S.; Kamel, M.A.; Taha, H.O.; Ammar, H.Y.; Abdel Halim, W.S.

    2006-01-01

    The oxidation states of Thallium in F A1 Tl +n (n = 1, 3) color centers at the (1 0 0) surface of NaCl play important role in laser light generation and adsorbate-substrate interactions. Double-well potentials at these surfaces are investigated by using quantum mechanical ab initio methods. Quantum clusters of variable sizes were embedded in the simulated Coulomb fields that closely approximate the Madelung fields of the host surfaces, and ions that were the nearest neighbors to the F A1 Tl +n (n 1, 3) defect site were allowed to relax to equilibrium.The calculated Stokes shifts suggest that laser light generation is sensitive to the oxidation states of Thallium. The relaxed excited states of the defect-containing surface were deep below the lower edge of the conduction bands of the ground state defect-free surface, suggesting that the F A1 Tl +n (n = 1, 3) centers are suitable laser defects. The dependence of the orientational destruction and recording sensitivity on the oxidation state of Thallium is clarified. The Glasner-Tompkins empirical rule is generalized to include the oxidation state of the impurity cation. The adsorption energies of CO and OC over NaCl(1 0 0) was found to be sensitive to the oxidation state of the impurity cation. F A1 Tl +n (n = 1, 3) centers changed the physical adsorption of CO to chemical adsorption. While the artificial flow of charge was significant in the case of Tl +1 impurity, it was negligible in the case of Tl +3 impurity, and the results were explained in terms of the electrostatic potential curves

  14. Development of Lithium-Stuffed Garnet-Type Oxide Solid Electrolytes with High Ionic Conductivity for Application to All-Solid-State Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Inada, Ryoji, E-mail: inada@ee.tut.ac.jp; Yasuda, Satoshi; Tojo, Masaru; Tsuritani, Keiji; Tojo, Tomohiro; Sakurai, Yoji [Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Toyohashi (Japan)

    2016-07-20

    All-solid-state lithium-ion batteries are expected to be one of the next generations of energy storage devices because of their high energy density, high safety, and excellent cycle stability. Although oxide-based solid electrolyte (SE) materials have rather lower conductivity and poor deformability than sulfide-based ones, they have other advantages, such as their chemical stability and ease of handling. Among the various oxide-based SEs, lithium-stuffed garnet-type oxide, with the formula of Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} (LLZ), has been widely studied because of its high conductivity above 10{sup −4} S cm{sup −1} at room temperature, excellent thermal performance, and stability against Li metal anode. Here, we present our recent progress for the development of garnet-type SEs with high conductivity by simultaneous substitution of Ta{sup 5+} into the Zr{sup 4+} site and Ba{sup 2+} into the La{sup 3+} site in LLZ. Li{sup +} concentration was fixed to 6.5 per chemical formulae, so that the formula of our Li garnet-type oxide is expressed as Li{sub 6.5}La{sub 3−x}Ba{sub x}Zr{sub 1.5−x}Ta{sub 0.5+x}O{sub 12} (LLBZT) and Ba contents x are changed from 0 to 0.3. As a result, all LLBZT samples have a cubic garnet structure without containing any secondary phases. The lattice parameters of LLBZT decrease with increasing Ba{sup 2+} contents x ≤ 0.10 while increase with x from 0.10 to 0.30, possibly due to the simultaneous change of Ba{sup 2+} and Ta{sup 5+} substitution levels. The relative densities of LLBZT are in a range between 89 and 93% and are not influenced in any significant way by the compositions. From the AC impedance spectroscopy measurements, the total (bulk + grain) conductivity at 27°C of LLBZT shows its maximum value of 8.34 × 10{sup −4} S cm{sup −1} at x = 0.10, which is slightly higher than the conductivity (= 7.94 × 10{sup −4} S cm{sup −1}) of LLZT without substituting Ba (x = 0). The activation energy of the conductivity

  15. A record of deep-ocean dissolved O2 from the oxidation state of iron in submarine basalts

    Science.gov (United States)

    Stolper, Daniel A.; Keller, C. Brenhin

    2018-01-01

    The oxygenation of the deep ocean in the geological past has been associated with a rise in the partial pressure of atmospheric molecular oxygen (O2) to near-present levels and the emergence of modern marine biogeochemical cycles. It has also been linked to the origination and diversification of early animals. It is generally thought that the deep ocean was largely anoxic from about 2,500 to 800 million years ago, with estimates of the occurrence of deep-ocean oxygenation and the linked increase in the partial pressure of atmospheric oxygen to levels sufficient for this oxygenation ranging from about 800 to 400 million years ago. Deep-ocean dissolved oxygen concentrations over this interval are typically estimated using geochemical signatures preserved in ancient continental shelf or slope sediments, which only indirectly reflect the geochemical state of the deep ocean. Here we present a record that more directly reflects deep-ocean oxygen concentrations, based on the ratio of Fe3+ to total Fe in hydrothermally altered basalts formed in ocean basins. Our data allow for quantitative estimates of deep-ocean dissolved oxygen concentrations from 3.5 billion years ago to 14 million years ago and suggest that deep-ocean oxygenation occurred in the Phanerozoic (541 million years ago to the present) and potentially not until the late Palaeozoic (less than 420 million years ago).

  16. A record of deep-ocean dissolved O2 from the oxidation state of iron in submarine basalts.

    Science.gov (United States)

    Stolper, Daniel A; Keller, C Brenhin

    2018-01-18

    The oxygenation of the deep ocean in the geological past has been associated with a rise in the partial pressure of atmospheric molecular oxygen (O 2 ) to near-present levels and the emergence of modern marine biogeochemical cycles. It has also been linked to the origination and diversification of early animals. It is generally thought that the deep ocean was largely anoxic from about 2,500 to 800 million years ago, with estimates of the occurrence of deep-ocean oxygenation and the linked increase in the partial pressure of atmospheric oxygen to levels sufficient for this oxygenation ranging from about 800 to 400 million years ago. Deep-ocean dissolved oxygen concentrations over this interval are typically estimated using geochemical signatures preserved in ancient continental shelf or slope sediments, which only indirectly reflect the geochemical state of the deep ocean. Here we present a record that more directly reflects deep-ocean oxygen concentrations, based on the ratio of Fe 3+ to total Fe in hydrothermally altered basalts formed in ocean basins. Our data allow for quantitative estimates of deep-ocean dissolved oxygen concentrations from 3.5 billion years ago to 14 million years ago and suggest that deep-ocean oxygenation occurred in the Phanerozoic (541 million years ago to the present) and potentially not until the late Palaeozoic (less than 420 million years ago).

  17. Influence of 2-Weeks Ingestion of High Chlorogenic Acid Coffee on Mood State, Performance, and Postexercise Inflammation and Oxidative Stress: A Randomized, Placebo-Controlled Trial.

    Science.gov (United States)

    Nieman, David C; Goodman, Courtney L; Capps, Christopher R; Shue, Zack L; Arnot, Robert

    2018-01-01

    This study measured the influence of 2-weeks ingestion of high chlorogenic acid (CQA) coffee on postexercise inflammation and oxidative stress, with secondary outcomes including performance and mood state. Cyclists (N = 15) were randomized to CQA coffee or placebo (300 ml/day) for 2 weeks, participated in a 50-km cycling time trial, and then crossed over to the opposite condition with a 2-week washout period. Blood samples were collected pre- and postsupplementation, and immediately postexercise. CQA coffee was prepared using the Turkish method with 30 g lightly roasted, highly ground Hambela coffee beans in 300 ml boiling water, and provided 1,066 mg CQA and 474 mg caffeine versus 187 mg CQA and 33 mg caffeine for placebo. Plasma caffeine was higher with CQA coffee versus placebo after 2-weeks (3.3-fold) and postexercise (21.0-fold) (interaction effect, p coffee versus placebo (p = .01). No differences between CQA coffee and placebo were found for postexercise increases in plasma IL-6 (p = .74) and hydroxyoctadecadienoic acids (9 + 13 HODEs) (p = .99). Total mood disturbance (TMD) scores were lower with CQA coffee versus placebo (p = .04). 50-km cycling time performance and power did not differ between trials, with heart rate and ventilation higher with CQA coffee, especially after 30 min. In summary, despite more favorable TMD scores with CQA coffee, these data do not support the chronic use of coffee highly concentrated with chlorogenic acids and caffeine in mitigating postexercise inflammation or oxidative stress or improving 50-km cycling performance.

  18. Scan-Mode Atmospheric-Pressure Plasma Jet Processed Reduced Graphene Oxides for Quasi-Solid-State Gel-Electrolyte Supercapacitors

    Directory of Open Access Journals (Sweden)

    Aliyah R. Hsu

    2018-01-01

    Full Text Available A scanning atmospheric-pressure plasma jet (APPJ is essential for high-throughput large-area and roll-to-roll processes. In this study, we evaluate scan-mode APPJ for processing reduced graphene oxides (rGOs that are used as the electrodes of quasi-solid-state gel-electrolyte supercapacitors. rGO nanoflakes are mixed with ethyl cellulose (EC and terpineol to form pastes for screen-printing. After screen-printing the pastes on carbon cloth, a DC-pulse nitrogen APPJ is used to process the pastes in the scan mode. The maximal temperature attained is ~550 °C with a thermal influence duration of ~10 s per scan. The pastes are scanned by APPJ for 0, 1, 3 and 5 times. X-ray photoelectron spectroscopy (XPS indicates the reduction of C-O binding content as the number of scan increases, suggesting the oxidation/decomposition of EC. The areal capacitance increases and then decreases as the number of scan increases; the best achieved areal capacitance is 15.93 mF/cm2 with one APPJ scan, in comparison to 4.38 mF/cm2 without APPJ processing. The capacitance retention rate of the supercapacitor with the best performance is ~93% after a 1000-cycle cyclic voltammetry (CV test. The optimal number of APPJ scans should enable the proper removal of inactive EC and improved wettability while minimizing the damage caused to rGOs by nitrogen APPJ processing.

  19. Bioavailability of Compounds Susceptible to Enzymatic Oxidation Enhances Growth of Shiitake Medicinal Mushroom (Lentinus edodes) in Solid-State Fermentation with Vineyard Prunings.

    Science.gov (United States)

    Cabrera, Rosina; López-Peña, Damian; Asaff, Ali; Esqueda, Martín; Valenzuela-Soto, Elisa M

    2018-01-01

    Grapes are widely produced in northwestern Mexico, generating many wood trimmings (vineyard prunings) that have no further local use. This makes vineyard prunings a very attractive alternative for the cultivation of white-rot medicinal mushrooms such as Lentinus edodes. This type of wood can also offer a model for the evaluation of oxidative enzyme production during the fermentation process. We tested the effect of wood from vineyard prunings on the vegetative growth of and production of ligninolytic enzymes in L. edodes in solid-state fermentation and with wheat straw as the control substrate. The specific growth rate of the fungus was 2-fold higher on vineyard pruning culture (μM = 0.95 day-1) than on wheat straw culture (μM = 0.47 day-1). Laccase-specific production was 4 times higher in the vineyard prunings culture than on wheat straw (0.34 and 0.08 mU · mg protein-1 · ppm CO2-1, respectively), and manganese peroxidase production was 3.7 times higher on wheat straw culture than on vineyard prunings (2.21 and 0.60 mU · mg protein-1 · ppm CO2-1, respectively). To explain accurately these differences in growth and ligninolytic enzyme activity, methanol extracts were obtained from each substrate and characterized. Resveratrol and catechins were the main compounds identified in vineyard prunings, whereas epigallocatechin was the only one detected in wheat straw. Compounds susceptible to enzymatic oxidation are more bioavailable in vineyard prunings than in wheat straw, and thus the highest L. edodes growth rate is associated with the presence of these compounds.

  20. Novel Non-Stoichiometric Manganese – Cobalt – Nickel – Oxide Composite as Humidity Sensor Through Solid-State Electrical Conductivity Measurements

    Directory of Open Access Journals (Sweden)

    R. Sundaram

    2006-08-01

    Full Text Available Equimolar amounts of manganese(II chloride, cobalt(III nitrate and nickel(II chloride in aqueous solution were reacted with ammonia and the resulting precipitate of hydroxides was heated to 7500 C in 6h to yield a non stoichiometric oxides having a composition of Mn0.06Co0.6Ni0.6O2.5 as analyzed by atomic absorption spectroscopy to a pellet and sintered at 6000 C. Characterization of the material has been made with AAS, Far-IR, TG-DTA, XRD, SEM, VSM and electrical conductance measurement. The far-IR spectra indicated the presence of metal-oxygen bonds and the discrete nature of the oxide was established from power X-ray diffraction pattern recorded at room temperature. The thermogravimetric data indicated the successive loss and gain of fraction of oxygen atoms, a specific feature of non-stoichiometric metal oxides. It was subjected to solid-state DC electrical conductivity measurements at room temperature. The current increases linearly with applied field and exponentially with increase in temperature showing conformance to ohmic law and semiconducting nature. The scanning electron microscopy (SEM studies were carried out to study the surface and pores structure of the sensor materials. The Brunauer-Emmett-Teller (BET surface adsorption studies showed that the radiuses of the pore sizes were found to be distributed from 10-45A with the pore specific volume being 0.01 cm3 g-1. As the composites having micropores are preferred for humidity sensing properties, the material was subjected to water vapour of different humidity achieved by various water buffers at room temperature and the electrical conductivity was measured as a function of relative humidity (RH. The electrical resistivity drastically decreases with increase in humidity, proving the material to be a good water vapour sensor. The sensitivity factor (Sf was 55000 in the range 5–98% RH, meaning the resistivity falls by a factor of 5.5 x 104 when the atmospheric RH increases from 5

  1. OXIDATION OF TRANSURANIC ELEMENTS

    Science.gov (United States)

    Moore, R.L.

    1959-02-17

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

  2. 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.

  3. Phosphide oxides RE2AuP2O (RE = La, Ce, Pr, Nd): synthesis, structure, chemical bonding, magnetism, and 31P and 139La solid state NMR.

    Science.gov (United States)

    Bartsch, Timo; Wiegand, Thomas; Ren, Jinjun; Eckert, Hellmut; Johrendt, Dirk; Niehaus, Oliver; Eul, Matthias; Pöttgen, Rainer

    2013-02-18

    Polycrystalline samples of the phosphide oxides RE(2)AuP(2)O (RE = La, Ce, Pr, Nd) were obtained from mixtures of the rare earth elements, binary rare earth oxides, gold powder, and red phosphorus in sealed silica tubes. Small single crystals were grown in NaCl/KCl fluxes. The samples were studied by powder X-ray diffraction, and the structures were refined from single crystal diffractometer data: La(2)AuP(2)O type, space group C2/m, a = 1515.2(4), b = 424.63(8), c = 999.2(2) pm, β = 130.90(2)°, wR2 = 0.0410, 1050 F(2) values for Ce(2)AuP(2)O, and a = 1503.6(4), b = 422.77(8), c = 993.0(2) pm, β = 130.88(2)°, wR2 = 0.0401, 1037 F(2) values for Pr(2)AuP(2)O, and a = 1501.87(5), b = 420.85(5), c = 990.3(3) pm, β = 131.12(1)°, wR2 = 0.0944, 1143 F(2) values for Nd(2)AuP(2)O with 38 variables per refinement. The structures are composed of [RE(2)O](4+) polycationic chains of cis-edge-sharing ORE(4/2) tetrahedra and polyanionic strands [AuP(2)](4-), which contain gold in almost trigonal-planar phosphorus coordination by P(3-) and P(2)(4-) entities. The isolated phosphorus atoms and the P(2) pairs in La(2)AuP(2)O could clearly be distinguished by (31)P solid state NMR spectroscopy and assigned on the basis of a double quantum NMR technique. Also, the two crystallographically inequivalent La sites could be distinguished by static (139)La NMR in conjunction with theoretical electric field gradient calculations. Temperature-dependent magnetic susceptibility measurements show diamagnetic behavior for La(2)AuP(2)O. Ce(2)AuP(2)O and Pr(2)AuP(2)O are Curie-Weiss paramagnets with experimental magnetic moments of 2.35 and 3.48 μ(B) per rare earth atom, respectively. Their solid state (31)P MAS NMR spectra are strongly influenced by paramagnetic interactions. Ce(2)AuP(2)O orders antiferromagnetically at 13.1(5) K and shows a metamagnetic transition at 11.5 kOe. Pr(2)AuP(2)O orders ferromagnetically at 7.0 K.

  4. Solid oxide fuel cells fueled with reducible oxides

    Science.gov (United States)

    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.

  5. Trap state passivation improved hot-carrier instability by zirconium-doping in hafnium oxide in a nanoscale n-metal-oxide semiconductor-field effect transistors with high-k/metal gate

    International Nuclear Information System (INIS)

    Liu, Hsi-Wen; Tsai, Jyun-Yu; Liu, Kuan-Ju; Lu, Ying-Hsin; Chang, Ting-Chang; Chen, Ching-En; Tseng, Tseung-Yuen; Lin, Chien-Yu; Cheng, Osbert; Huang, Cheng-Tung; Ye, Yi-Han

    2016-01-01

    This work investigates the effect on hot carrier degradation (HCD) of doping zirconium into the hafnium oxide high-k layer in the nanoscale high-k/metal gate n-channel metal-oxide-semiconductor field-effect-transistors. Previous n-metal-oxide semiconductor-field effect transistor studies demonstrated that zirconium-doped hafnium oxide reduces charge trapping and improves positive bias temperature instability. In this work, a clear reduction in HCD is observed with zirconium-doped hafnium oxide because channel hot electron (CHE) trapping in pre-existing high-k bulk defects is the main degradation mechanism. However, this reduced HCD became ineffective at ultra-low temperature, since CHE traps in the deeper bulk defects at ultra-low temperature, while zirconium-doping only passivates shallow bulk defects.

  6. Remarkable changes in the photoluminescent properties of Y2Ce2O7:Eu(3+) red phosphors through modification of the cerium oxidation states and oxygen vacancy ordering.

    Science.gov (United States)

    Raj, Athira K V; Prabhakar Rao, P; Sreena, T S; Sameera, S; James, Vineetha; Renju, U A

    2014-11-21

    A new series of red phosphors based on Eu(3+)-doped yttrium cerate [Y1.9Ce2O7:0.1Eu(3+), Y2Ce1.9O7:0.1Eu(3+) and Y2Ce2-xO7:xEu(3+) (x = 0.05, 0.10, 0.15, 0.20, 0.25 and 0.50)] was prepared via a conventional solid-state method. The influence of the substitution of Eu(3+) at the aliovalent site on the photoluminescent properties was determined by powder X-ray diffraction, FT Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy with energy-dispersive spectroscopy, UV-visible absorption spectroscopy, photoluminescence spectroscopy and lifetime measurements. The substitution of Eu(3+) at the Ce(4+) site induces a structural transition from a defect fluorite to a C-type structure, which increases the oxygen vacancy ordering and the distortion of the Eu(3+) environment, and decreases the formation of Ce(3+) states. In contrast, phosphors with isovalent substitution at the Y(3+) site exhibit the biphasic nature of defect fluorite and a C-type structure, thereby increasing the number of Ce(3+) oxidation states. These modifications resulted in remarkable changes in the photoluminescent properties of Y2Ce1.9O7:0.1Eu(3+) red phosphors, with emission intensities 3.8 times greater than those of the Ce0.9O2:0.1Eu(3+) and Y1.9Ce2O7:0.1Eu(3+). The photoluminescent properties of Y2Ce2-xO7:xEu(3+) were studied at different Eu(3+) concentrations under excitation with blue light. These phosphors emit intense red light due to the (5)D0-(7)F2 transition under excitation at 466 nm and no concentration quenching is observed with up to 50 mol% Eu(3+). They show increased lifetimes in the range 0.62-0.72 ms at Eu(3+) concentrations. The cation ordering linked to the oxygen vacancy ordering led to the uniform distribution of Eu(3+) ions in the lattice, thus allowing higher doping concentrations without quenching and consequently increasing the lifetime of the (5)D0 states. Our results demonstrate that significant improvements in

  7. Evolution of Defect Structures and Deep Subgap States during Annealing of Amorphous In-Ga-Zn Oxide for Thin-Film Transistors

    Science.gov (United States)

    Jia, Junjun; Suko, Ayaka; Shigesato, Yuzo; Okajima, Toshihiro; Inoue, Keiko; Hosomi, Hiroyuki

    2018-01-01

    We investigate the evolution behavior of defect structures and the subgap states in In-Ga-Zn oxide (IGZO) films with increasing postannealing temperature by means of extended x-ray absorption fine-structure (EXAFS) measurements, positron annihilation lifetime spectroscopy (PALS), and cathodoluminescence (CL) spectroscopy, aiming to understand the relationship between defect structures and subgap states. EXAFS measurements reveal the varied oxygen coordination numbers around cations during postannealing and confirm two types of point defects, namely, excess oxygen around Ga atoms and oxygen deficiency around In and/or Zn atoms. PALS suggests the existence of cation-vacancy (VM )-related clusters with neutral or negative charge in both amorphous and polycrystalline IGZO films. CL spectra show a main emission band at approximately 1.85 eV for IGZO films, and a distinct shoulder located at about 2.15 eV for IGZO films postannealed above 600 °C . These two emission bands are assigned to a recombination between the electrons in the conduction band and/or in the shallow donor levels near the conduction band and the acceptors trapped above the valence-band maximum. The shallow donors are attributed to the oxygen deficiency, and the acceptors are thought to possibly arise from the excess oxygen or the VM-related clusters. These results open up an alternative route for understanding the device instability of amorphous IGZO-based thin-film transistors, especially the presence of the neutral or negatively charged VM-related clusters in amorphous IGZO films.

  8. A new phosphine oxide host based on ortho-disubstituted dibenzofuran for efficient electrophosphorescence: towards high triplet state excited levels and excellent thermal, morphological and efficiency stability.

    Science.gov (United States)

    Han, Chunmiao; Xie, Guohua; Li, Jing; Zhang, Zhensong; Xu, Hui; Deng, Zhaopeng; Zhao, Yi; Yan, Pengfei; Liu, Shiyong

    2011-08-01

    An efficient host for blue and green electrophosphorescence, 4,6-bis(diphenylphosphoryl)dibenzofuran (o-DBFDPO), with the structure of a short-axis-substituted dibenzofuran was designed and synthesised. It appears that the greater density of the diphenylphosphine oxide (DPPO) moieties in the short-axis substitution configuration effectively restrains the intermolecular interactions, because only very weak π-π stacking interactions could be observed, with a centroid-to-centroid distance of 3.960 Å. The improved thermal stability of o-DBFDPO was corroborated by its very high glass transition temperature (T(g)) of 191 °C, which is the result of the symmetric disubstitution structure. Photophysical investigation showed o-DBFDPO to be superior to the monosubstituted derivative, with a longer lifetime (1.95 ns) and a higher photoluminescent quantum efficiency (61 %). The lower first singlet state excited level (3.63 eV) of o-DBFDPO demonstrates the stronger polarisation effect attributable to the greater number of DPPO moieties. Simultaneously, an extremely high first triplet state excited level (T(1)) of 3.16 eV is observed, demonstrating the tiny influence of short-axis substitution on T(1). The improved carrier injection ability, which contributed to low driving voltages of blue- and green-emitting phosphorescent organic light-emitting diodes (PHOLEDs), was further confirmed by Gaussian calculation. Furthermore, the better thermal and morphological properties of o-DBFDPO and the matched frontier molecular orbital (FMO) levels in the devices significantly reduced efficiency roll-offs. Efficient blue and green electrophosphorescence based on the o-DBFDPO host was demonstrated. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Evaluation of advanced oxidative processes in contaminated soil of the Pernambuco state; Avaliacao dos processos oxidativos avancados num solo contaminado do estado de Pernambuco

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Paula T.S. e [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Quimica; Santos, Suenia S. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Engenharia Quimica; Barros Neto, Benicio de [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Quimica Fundamental; Dorea, Haroldo S. [Universidade Federal de Sergipe (UFS), Aracaju, SE (Brazil); Motta Sobrinho, Mauricio A. da; Silva, Valdinete L. da [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil)

    2004-07-01

    In this work were used the following techniques of advanced oxidative processes: hydrogen peroxide, Fenton reagent and heterogeneous photocatalysis (TiO2). These processes have shown as an alternative technology to the treatment of some environmental matrices. The soil studied was contaminated by an oil mixture proceeding from an emptying in the patio of an industry of the state of Pernambuco. This soil has about 14,5 g/Kg of total organic carbon and 3400 mg/kg of TPH. Two planning factorial 23 were composed: one in relation to hydrogen peroxide and the other to titanium dioxide, in order to find the best conditions for the contaminant degradation. The variables and the studied levels for the former was: FeSO4 - 0,18 M (without, 4 and 8 ml); Adjustment of pH (3, without, without); Time of exposition to the sun (8h, 12h, 16h). The volumes of used peroxide in the assays were 80 and 40 ml. In relation to the second planning, were studied the following conditions: TiO2 (g) (without,5;0,75;1,0), volume H2O (0, 2,5 and 5 ml) and time of exposition to the sun (8, 40, 72h). In relation to the first planning a destruction of 84% of the oil was achieved. However, in relation to 2nd the planning non-significant degradation was obtained, and to study other conditions ought to be investigated. (author)

  10. Hybrid fibers made of molybdenum disulfide, reduced graphene oxide, and multi-walled carbon nanotubes for solid-state, flexible, asymmetric supercapacitors.

    Science.gov (United States)

    Sun, Gengzhi; Zhang, Xiao; Lin, Rongzhou; Yang, Jian; Zhang, Hua; Chen, Peng

    2015-04-07

    One of challenges existing in fiber-based supercapacitors is how to achieve high energy density without compromising their rate stability. Owing to their unique physical, electronic, and electrochemical properties, two-dimensional (2D) nanomaterials, e.g., molybdenum disulfide (MoS2 ) and graphene, have attracted increasing research interest and been utilized as electrode materials in energy-related applications. Herein, by incorporating MoS2 and reduced graphene oxide (rGO) nanosheets into a well-aligned multi-walled carbon nanotube (MWCNT) sheet followed by twisting, MoS2 -rGO/MWCNT and rGO/MWCNT fibers are fabricated, which can be used as the anode and cathode, respectively, for solid-state, flexible, asymmetric supercapacitors. This fiber-based asymmetric supercapacitor can operate in a wide potential window of 1.4 V with high Coulombic efficiency, good rate and cycling stability, and improved energy density. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. A feasibility study on oxidation state of arsenic in cut tobacco, mainstream cigarette smoke and cigarette ash by X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Liu, C.; Hu, J.; McAdam, K.G.

    2009-01-01

    This work describes the application of synchrotron-based X-ray Absorption Near-Edge Structure spectroscopy to study the oxidation state of arsenic in cigarette mainstream smoke, cut tobacco and cigarette ash. The level of arsenic in the total particulate matter of the smoke is approximately 1 ppm for the standard research reference cigarette 2R4F and its replacement 3R4F. Smoke particulate samples collected by a conventional glass-fiber membrane (commercially known as Cambridge filter pad) and a jet-impaction method were analyzed and compared. In addition smoke particulate samples were aged either at ambient temperature or at 195 K. X-ray Absorption Near-Edge Structure spectroscopy results revealed that the cut tobacco powder and cigarette ash contained almost exclusively As V . The smoke particulate samples however contained a mixture of As III and As V . The As V in the smoke particulate was reduced to As III upon aging. Stabilizing the smoke particulate matter at 195 K by solid CO 2 slowed down this aging reaction and revealed a higher percentage of As V . This behavior is consistent with the redox properties of the arsenic species and the smoke particulate matrix.

  12. Boron cross-linked graphene oxide/polyvinyl alcohol nanocomposite gel electrolyte for flexible solid-state electric double layer capacitor with high performance

    KAUST Repository

    Huang, Yi-Fu; Wu, Peng-Fei; Zhang, Ming-Qiu; Ruan, Wen-Hong; Giannelis, Emmanuel P.

    2014-01-01

    A new family of boron cross-linked graphene oxide/polyvinyl alcohol (GO-B-PVA) nanocomposite gels is prepared by freeze-thaw/boron cross-linking method. Then the gel electrolytes saturated with KOH solution are assembled into electric double layer capacitors (EDLCs). Structure, thermal and mechanical properties of GO-B-PVA are explored. The electrochemical properties of EDLCs using GO-B-PVA/KOH are investigated, and compared with those using GO-PVA/KOH gel or KOH solution electrolyte. FTIR shows that boron cross-links are introduced into GO-PVA, while the boronic structure inserted into agglomerated GO sheets is demonstrated by DMA analysis. The synergy effect of the GO and the boron crosslinking benefits for ionic conductivity due to unblocking ion channels, and for improvement of thermal stability and mechanical properties of the electrolytes. Higher specific capacitance and better cycle stability of EDLCs are obtained by using the GO-B-PVA/KOH electrolyte, especially the one at higher GO content. The nanocomposite gel electrolytes with excellent electrochemical properties and solid-like character are candidates for the industrial application in high-performance flexible solid-state EDLCs. © 2014 Elsevier Ltd.

  13. A solid-state thin-film Ag/AgCl reference electrode coated with graphene oxide and its use in a pH sensor.

    Science.gov (United States)

    Kim, Tae Yong; Hong, Sung A; Yang, Sung

    2015-03-17

    In this study, we describe a novel solid-state thin-film Ag/AgCl reference electrode (SSRE) that was coated with a protective layer of graphene oxide (GO). This layer was prepared by drop casting a solution of GO on the Ag/AgCl thin film. The potential differences exhibited by the SSRE were less than 2 mV for 26 days. The cyclic voltammograms of the SSRE were almost similar to those of a commercial reference electrode, while the diffusion coefficient of Fe(CN)63- as calculated from the cathodic peaks of the SSRE was 6.48 × 10-6 cm2/s. The SSRE was used in conjunction with a laboratory-made working electrode to determine its suitability for practical use. The average pH sensitivity of this combined sensor was 58.5 mV/pH in the acid-to-base direction; the correlation coefficient was greater than 0.99. In addition, an integrated pH sensor that included the SSRE was packaged in a secure digital (SD) card and tested. The average sensitivity of the chip was 56.8 mV/pH, with the correlation coefficient being greater than 0.99. In addition, a pH sensing test was also performed by using a laboratory-made potentiometer, which showed a sensitivity of 55.4 mV/pH, with the correlation coefficient being greater than 0.99.

  14. FRAPCON-3: A computer code for the calculation of steady-state, thermal-mechanical behavior of oxide fuel rods for high burnup

    International Nuclear Information System (INIS)

    Berna, G.A.; Beyer, G.A.; Davis, K.L.; Lanning, D.D.

    1997-12-01

    FRAPCON-3 is a FORTRAN IV computer code that calculates the steady-state response of light water reactor fuel rods during long-term burnup. The code calculates the temperature, pressure, and deformation of a fuel rod as functions of time-dependent fuel rod power and coolant boundary conditions. The phenomena modeled by the code include (1) heat conduction through the fuel and cladding, (2) cladding elastic and plastic deformation, (3) fuel-cladding mechanical interaction, (4) fission gas release, (5) fuel rod internal gas pressure, (6) heat transfer between fuel and cladding, (7) cladding oxidation, and (8) heat transfer from cladding to coolant. The code contains necessary material properties, water properties, and heat-transfer correlations. The codes' integral predictions of mechanical behavior have not been assessed against a data base, e.g., cladding strain or failure data. Therefore, it is recommended that the code not be used for analyses of cladding stress or strain. FRAPCON-3 is programmed for use on both mainframe computers and UNIX-based workstations such as DEC 5000 or SUN Sparcstation 10. It is also programmed for personal computers with FORTRAN compiler software and at least 8 to 10 megabytes of random access memory (RAM). The FRAPCON-3 code is designed to generate initial conditions for transient fuel rod analysis by the FRAPTRAN computer code (formerly named FRAP-T6)

  15. Comparative Studies on Thermal, Mechanical, and Flame Retardant Properties of PBT Nanocomposites via Different Oxidation State Phosphorus-Containing Agents Modified Amino-CNTs.

    Science.gov (United States)

    Zhu, San-E; Wang, Li-Li; Chen, Hao; Yang, Wei; Yuen, Anthony Chun-Yin; Chen, Timothy Bo-Yuan; Luo, Cheng; Bi, Wen-Mei; Hu, En-Zhu; Zhang, Jian; Si, Jing-Yu; Lu, Hong-Dian; Hu, Kun-Hong; Chan, Qing Nian; Yeoh, Guan Heng

    2018-01-26

    High-performance poly(1,4-butylene terephthalate) (PBT) nanocomposites have been developed via the consideration of phosphorus-containing agents and amino-carbon nanotube (A-CNT). One-pot functionalization method has been adopted to prepare functionalized CNTs via the reaction between A-CNT and different oxidation state phosphorus-containing agents, including chlorodiphenylphosphine (DPP-Cl), diphenylphosphinic chloride (DPP(O)-Cl), and diphenyl phosphoryl chloride (DPP(O₃)-Cl). These functionalized CNTs, DPP(O x )-A-CNTs ( x = 0, 1, 3), were, respectively, mixed with PBT to obtain the CNT-based polymer nanocomposites through a melt blending method. Scanning electron microscope observations demonstrated that DPP(O x )-A-CNT nanoadditives were homogeneously distributed within PBT matrix compared to A-CNT. The incorporation of DPP(O x )-A-CNT improved the thermal stability of PBT. Moreover, PBT/DPP(O₃)-A-CNT showed the highest crystallization temperature and tensile strength, due to the superior dispersion and interfacial interactions between DPP(O₃)-A-CNT and PBT. PBT/DPP(O)-A-CNT exhibited the best flame retardancy resulting from the excellent carbonization effect. The radicals generated from decomposed polymer were effectively trapped by DPP(O)-A-CNT, leading to the reduction of heat release rate, smoke production rate, carbon dioxide and carbon monoxide release during cone calorimeter tests.

  16. Boron cross-linked graphene oxide/polyvinyl alcohol nanocomposite gel electrolyte for flexible solid-state electric double layer capacitor with high performance

    International Nuclear Information System (INIS)

    Huang, Yi-Fu; Wu, Peng-Fei; Zhang, Ming-Qiu; Ruan, Wen-Hong; Giannelis, Emmanuel P.

    2014-01-01

    Highlights: • Gel electrolyte is prepared and used in electric double layer capacitor. • Insertion of boron crosslinks into GO agglomerates opens channels for ion migration. • Solid supercapacitors show excellent specific capacitance and cycle stability. • Nanocomposite electrolyte shows better thermal stability and mechanical properties. - Abstract: A new family of boron cross-linked graphene oxide/polyvinyl alcohol (GO-B-PVA) nanocomposite gels is prepared by freeze-thaw/boron cross-linking method. Then the gel electrolytes saturated with KOH solution are assembled into electric double layer capacitors (EDLCs). Structure, thermal and mechanical properties of GO-B-PVA are explored. The electrochemical properties of EDLCs using GO-B-PVA/KOH are investigated, and compared with those using GO-PVA/KOH gel or KOH solution electrolyte. FTIR shows that boron cross-links are introduced into GO-PVA, while the boronic structure inserted into agglomerated GO sheets is demonstrated by DMA analysis. The synergy effect of the GO and the boron crosslinking benefits for ionic conductivity due to unblocking ion channels, and for improvement of thermal stability and mechanical properties of the electrolytes. Higher specific capacitance and better cycle stability of EDLCs are obtained by using the GO-B-PVA/KOH electrolyte, especially the one at higher GO content. The nanocomposite gel electrolytes with excellent electrochemical properties and solid-like character are candidates for the industrial application in high-performance flexible solid-state EDLCs

  17. A criterion based on computational singular perturbation for the identification of quasi steady state species: A reduced mechanism for methane oxidation with NO chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Tianfeng; Law, Chung K. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States)

    2008-09-15

    A criterion based on computational singular perturbation (CSP) is proposed to effectively distinguish the quasi steady state (QSS) species from the fast species induced by reactions in partial equilibrium. Together with the method of directed relation graph (DRG), it was applied to the reduction of GRI-Mech 3.0 for methane oxidation, leading to the development of a 19-species reduced mechanism with 15 lumped steps, with the concentrations of the QSS species solved analytically for maximum computational efficiency. Compared to the 12-step and 16-species augmented reduced mechanism (ARM) previously developed by Sung, Law and Chen, three species, namely O, CH{sub 3}OH, and CH{sub 2}CO, are now excluded from the QSS species list. The reduced mechanism was validated with a variety of phenomena including perfectly stirred reactors, auto-ignition, and premixed and non-premixed flames, with the worst-case error being less than 10% over a wide range of parameters. This mechanism was then supplemented with the reactions involving NO formation, followed by validations in both homogeneous and diffusive systems. (author)

  18. Boron cross-linked graphene oxide/polyvinyl alcohol nanocomposite gel electrolyte for flexible solid-state electric double layer capacitor with high performance

    KAUST Repository

    Huang, Yi-Fu

    2014-06-01

    A new family of boron cross-linked graphene oxide/polyvinyl alcohol (GO-B-PVA) nanocomposite gels is prepared by freeze-thaw/boron cross-linking method. Then the gel electrolytes saturated with KOH solution are assembled into electric double layer capacitors (EDLCs). Structure, thermal and mechanical properties of GO-B-PVA are explored. The electrochemical properties of EDLCs using GO-B-PVA/KOH are investigated, and compared with those using GO-PVA/KOH gel or KOH solution electrolyte. FTIR shows that boron cross-links are introduced into GO-PVA, while the boronic structure inserted into agglomerated GO sheets is demonstrated by DMA analysis. The synergy effect of the GO and the boron crosslinking benefits for ionic conductivity due to unblocking ion channels, and for improvement of thermal stability and mechanical properties of the electrolytes. Higher specific capacitance and better cycle stability of EDLCs are obtained by using the GO-B-PVA/KOH electrolyte, especially the one at higher GO content. The nanocomposite gel electrolytes with excellent electrochemical properties and solid-like character are candidates for the industrial application in high-performance flexible solid-state EDLCs. © 2014 Elsevier Ltd.

  19. 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

  20. Heterometallic molecular precursors for a lithium-iron oxide material: synthesis, solid state structure, solution and gas-phase behaviour, and thermal decomposition.

    Science.gov (United States)

    Han, Haixiang; Wei, Zheng; Barry, Matthew C; Filatov, Alexander S; Dikarev, Evgeny V

    2017-05-02

    Three heterometallic single-source precursors with a Li : Fe = 1 : 1 ratio for a LiFeO 2 oxide material are reported. Heterometallic compounds LiFeL 3 (L = tbaoac (1), ptac (2), and acac(3)) have been obtained on a large scale, in nearly quantitative yields by one-step reactions that employ readily available reagents. The heterometallic precursor LiFe(acac) 3 (3) with small, symmetric substituents on the ligand (acac = pentane-2,4-dionate), maintains a 1D polymeric structure in the solid state that limits its volatility and prevents solubility in non-coordinating solvents. The application of the unsymmetrical ligands, tbaoac (tert-butyl acetoacetate) and ptac (1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedionate), that exhibit different bridging properties at the two ends of the ligand, allowed us to change the connectivity pattern within the heterometallic assembly. The latter was demonstrated by structural characterization of heterometallic complexes LiFe(tbaoac) 3 (1) and LiFe(ptac) 3 (2) that consist of discrete heterocyclic tetranuclear molecules Li 2 Fe 2 L 6 . The compounds are highly volatile and exhibit a congruent sublimation character. DART mass spectrometric investigation revealed the presence of heterometallic molecules in the gas phase. The positive mode spectra are dominated by the presence of [M - L] + peaks (M = Li 2 Fe 2 L 6 ). In accord with their discrete molecular structure, complexes 1 and 2 are highly soluble in nearly all common solvents. In order to test the retention of the heterometallic structure in solution, the diamagnetic analog of 1, LiMg(tbaoac) 3 (4), has been isolated. Its tetranuclear molecular structure was found to be isomorphous to that of the iron counterpart. 1 H and 7 Li NMR spectroscopy unambiguously confirmed the presence of heterometallic molecules in solutions of non-coordinating solvents. The heterometallic precursor 1 was shown to exhibit clean thermal decomposition in air that results in phase-pure

  1. Assigning the Cerium Oxidation State for CH2CeF2 and OCeF2 Based on Multireference Wave Function Analysis.

    Science.gov (United States)

    Mooßen, Oliver; Dolg, Michael

    2016-06-09

    The geometric and electronic structure of the recently experimentally studied molecules ZCeF2 (Z = CH2, O) was investigated by density functional theory (DFT) and wave function-based ab initio methods. Special attention was paid to the Ce-Z metal-ligand bonding, especially to the nature of the interaction between the Ce 4f and the Z 2p orbitals and the possible multiconfigurational character arising from it, as well as to the assignment of an oxidation state of Ce reflecting the electronic structure. Complete active space self-consistent field (CASSCF) calculations were performed, followed by orbital rotations in the active orbital space. The methylene compound CH2CeF2 has an open-shell singlet ground state, which is characterized by a two-configurational wave function in the basis of the strongly mixed natural CASSCF orbitals. The system can also be described in a very compact way by the dominant Ce 4f(1) C 2p(1) configuration, if nearly pure Ce 4f and C 2p orbitals are used. In the basis of these localized orbitals, the molecule is almost monoconfigurational and should be best described as a Ce(III) system. The singlet ground state of the oxygen OCeF2 complex is of closed-shell character when a monoconfigurational wave function with very strongly mixed Ce 4f and O 2p CASSCF natural orbitals is used for the description. The transformation to orbitals localized on the cerium and oxygen atoms leads to a multiconfigurational wave function and reveals characteristics of a mixed valent Ce(IV)/Ce(III) compound. Additionally, the interactions of the localized active orbitals were analyzed by evaluating the expectation values of the charge fluctuation operator and the local spin operator. The Ce 4f and C 2p orbital interaction of the CH2CeF2 compound is weakly covalent and resembles the interaction of the H 1s orbitals in a stretched hydrogen dimer. In contrast, the interaction of the localized active orbitals for OCeF2 shows ionic character. Calculated vibrational Ce

  2. High and low oxidation states and special bonding situations. An investigation of f-elements, xenon and fluorine by matrix-isolation spectroscopy and quantum-chemical calculations

    Energy Technology Data Exchange (ETDEWEB)

    Vent-Schmidt, Thomas

    2015-11-30

    During this thesis, the matrix-isolation technique in conjuction with quantum-chemical calculations has been employed in order to synthesize and characterize new compounds. The focus of the study were new species of the actinide and lanthanide series, but the photochemistry of XeO{sub 4} and the polyfluorides were also investigated. Based on the experience of laser ablated uranium and thorium atoms with H{sub 2} and F{sub 2} the reaction of these actinide atoms with HF has been investigated. The main products in these experiments are HThF and HUF which contain an actinide metal in the rather scarce +II oxidation state. In addition, the deuterated compounds have also been prepared and the isotopic shifts support the assignment. The higher hydride fluorides of thorium such as HThF{sub 3}, H{sub 2}ThF{sub 2} and H{sub 3}ThF have also been observed, whereas there is only little evidence for higher uranium hydride fluorides. The different behavior of the two metals under similar reaction conditions has been investigated theoretically. Besides the hydride fluorides, the reaction of the actinide atoms with HF gives also rise to the low valent fluorides and hydrides such as AnH and AnF (An = U, Th). These compounds have already been identified in experiments using fluorine or hydrogen as reagent, but a more reliable assignment can be made in these experiments due to the lower concentration of H or F. In addition, ThF{sub 2} has been observed in these experiments and there is evidence for the unknown difluoride of uranium, which will be addressed in a future paper. Experiments with laser ablated uranium and thorium atoms were extended to the reaction of these metals with H{sub 2}Se. Previous experiments using H{sub 2}O and H{sub 2}S instead of H{sub 2}Se yielded H{sub 2}AnX (An = U, Th; X = O, S) compounds which show evidence for an actinide-chalcogenide multiple bond. The new synthesized species H{sub 2}ThSe and H{sub 2}USe are characterized by their symmetric and

  3. The nature of the U=C double bond: pushing the stability of high-oxidation-state uranium carbenes to the limit

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, Oliver J.; Mills, David P.; McMaster, Jonathan; Lewis, William; Blake, Alexander J.; Liddle, Stephen T. [School of Chemistry, University of Nottingham (United Kingdom); Tuna, Floriana; McInnes, Eric J.L. [EPSRC National UK EPR Facility, School of Chemistry and Photon Science Institute, The University of Manchester (United Kingdom)

    2013-05-27

    . Theoretical calculations have enabled a qualitative bracketing of the extent of covalency in early-metal carbenes as a function of metal, oxidation state and the number of phosphanyl substituents, revealing modest covalent contributions to U=C double bonds. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. No effect of H2O degassing on the oxidation state of hydrous rhyolite magmas: a comparison of pre- and post-eruptive Fe2+ concentrations in six obsidian samples from the Mexican and Cascade arcs

    Science.gov (United States)

    Waters, L.; Lange, R. A.

    2011-12-01

    The extent to which degassing affects the oxidation state of arc magmas is widely debated. Several researchers have examined how degassing of mixed H-C-O-S-Cl fluids may change the Fe3+/FeT ratio of magmas, and it has been proposed that degassing may induce either oxidation or reduction depending on the initial oxidation state. A commonly proposed oxidation reaction is related to H2O degassing: H2O (melt) + 2FeO (melt) = H2 (fluid) + Fe2O3 (melt). Another mechanism by which H2O degassing can affect the iron redox state is if dissolved water affects the activity of ferrous and/or ferric iron in the melt. Although Moore et al. (1995) presented experiments showing no evidence of an affect of dissolved water on the activity of the ferric-ferrous ratio in silicate melts, other experimental results (e.g., Baker and Rutherford, 1996; Gaillard et al., 2001; 2003) indicate that there may be such an effect in rhyolite liquids. It has long been understood that rhyolites, owing to their low total iron concentrations, are more sensitive than other magma types to degassing-induced change in redox state. Therefore, a rigorous test of whether H2O degassing affects the redox state of arc magmas is best evaluated on rhyolites. In this study, a comparison is made between the pre-eruptive (pre-degassing) Fe2+ concentrations in six, phenocryst-poor (volatiles, as indicated by the low loss on ignition values (LOI ≤ 0.7 wt%). In order to test how much oxidation of ferrous iron occurred as a consequence of that degassing, we measured the ferrous iron concentration in the bulk samples by titration, using the Wilson (1960) method, which was successfully tested again three USGS and one Canadian Geological Survey standards. Our results indicate no detectable change within analytical error between pre- and post-eruptive FeO concentrations, with an average deviation of 0.09 wt% and a maximum deviation of 0.15 wt%. Our results show that H2O degassing has no effect on the redox state of

  5. One-electron oxidation of the hydroquinonic form of vitamin K by OH· and N3· free radicals. A steady-state gamma radiolysis study

    International Nuclear Information System (INIS)

    Nguyen Van Binh, E.; Gardes-Albert, M.; Ferradini, C.; Acher, F.; Azerad, R.

    1991-01-01

    The oxidation of a water-soluble model of vitamin K hydroquinone, symbolised by KH 2 p, has been studied by γ radiolysis using OH· or N 3 · free radicals as oxidants. Irradiation doses were up to 300 Gy. The analysis of final products by spectrophotometric absorption and HPLC allowed to characterize the formation of the quinone K and to estimate the initial yield of KH 2 p-disappearance and K-formation. N 3 · radicals led selectively to the formation of the quinone K with a G-value of (3.0 ± 0.3) x 10 -7 mol/J, thus involving a simple one-electron oxidation mechanism. On the contrary, when OH· radicals oxidized KH 2 p, in addition to the quinone, other non identified species were simultaneously produced during the radiolysis, thus requiring a more complex oxidation mechanism [fr

  6. Ethnic differences in five intronic polymorphisms associated with arsenic metabolism within human arsenic (+ 3 oxidation state) methyltransferase (AS3MT) gene

    International Nuclear Information System (INIS)

    Fujihara, Junko; Fujii, Yoshimi; Agusa, Tetsuro; Kunito, Takashi; Yasuda, Toshihiro; Moritani, Tamami; Takeshita, Haruo

    2009-01-01

    Human arsenic (+ 3 oxidation state) methyltransferase (AS3MT) is known to catalyze the methylation of arsenite, and intronic single-nucleotide polymorphisms (SNPs: G7395A, G12390C, T14215C, T35587C, and G35991A) in the AS3MT gene were shown to be related to inter-individual variation in the arsenic metabolism. In the present study, the genotyping for these SNPs was developed using the polymerase chain reaction and restriction fragment length polymorphism technique. Applying this method, the genotype distribution among the Ovambo, Turkish, Mongolian, Korean, and Japanese populations was investigated, and our results were compared with those from other studies. G7395, G12390, T35587, and A35991 were predominant among the five populations in our study. However, a previous study in Argentina, C12390 and G35991 showed the highest allele frequency among the eight populations studied in other studies. The dominant allele of T14215C differed among populations: the T14215 allele was predominant in Argentina, the allele frequency of C14215 was higher than that of T14215 among Turks, Mongolians, Europeans, and American ancestry. In Korea and Japan, similar allele frequencies were observed in T14215 and C14215. Higher allele frequencies were observed in haplotype G7395/G12390/C14215/T35587 with frequencies of 0.40 (Turks), 0.28 (Mongolians), and 0.23 (Koreans). On the other hand, the allele frequency for G7395/G14215/T35587/A35991 was the highest among the Ovambos (0.32), and the frequency for G7395/G12390/C35587/G35991 was the highest among the Japanese (0.27). It is noteworthy that the Japanese haplotype differs from that of the Koreans and Mongolians, which indicates the importance of investigating other intronic polymorphisms in AS3MT, especially in Asians

  7. Method to quantify the delocalization of electronic states in amorphous semiconductors and its application to assessing charge carrier mobility of p -type amorphous oxide semiconductors

    Science.gov (United States)

    de Jamblinne de Meux, A.; Pourtois, G.; Genoe, J.; Heremans, P.

    2018-01-01

    Amorphous semiconductors are usually characterized by a low charge carrier mobility, essentially related to their lack of long-range order. The development of such material with higher charge carrier mobility is hence challenging. Part of the issue comes from the difficulty encountered by first-principles simulations to evaluate concepts such as the electron effective mass for disordered systems since the absence of periodicity induced by the disorder precludes the use of common concepts derived from condensed matter physics. In this paper, we propose a methodology based on first-principles simulations that partially solves this problem, by quantifying the degree of delocalization of a wave function and of the connectivity between the atomic sites within this electronic state. We validate the robustness of the proposed formalism on crystalline and molecular systems and extend the insights gained to disordered/amorphous InGaZnO4 and Si. We also explore the properties of p -type oxide semiconductor candidates recently reported to have a low effective mass in their crystalline phases [G. Hautier et al., Nat. Commun. 4, 2292 (2013), 10.1038/ncomms3292]. Although in their amorphous phase none of the candidates present a valence band with delocalization properties matching those found in the conduction band of amorphous InGaZnO4, three of the seven analyzed materials show some potential. The most promising candidate, K2Sn2O3 , is expected to possess in its amorphous phase a slightly higher hole mobility than the electron mobility in amorphous silicon.

  8. Effects of nitric oxide synthesis inhibitor or fluoxetine treatment on depression-like state and cardiovascular changes induced by chronic variable stress in rats.

    Science.gov (United States)

    Almeida, Jeferson; Duarte, Josiane O; Oliveira, Leandro A; Crestani, Carlos C

    2015-01-01

    Comorbidity between mood disorders and cardiovascular disease has been described extensively. However, available antidepressants can have cardiovascular side effects. Treatment with selective inhibitors of neuronal nitric oxide synthase (nNOS) induces antidepressant effects, but whether the antidepressant-like effects of these drugs are followed by cardiovascular changes has not been previously investigated. Here, we tested in male rats exposed to chronic variable stress (CVS) the hypothesis that nNOS blockers are advantageous compared with conventional antidepressants in terms of cardiovascular side effects. We compared the effects of chronic treatment with the preferential nNOS inhibitor 7-nitroindazole (7-NI) with those evoked by the conventional antidepressant fluoxetine on alterations that are considered as markers of depression (immobility in the forced swimming test, FST, decreased body weight gain and increased plasma corticosterone concentration) and cardiovascular changes caused by CVS. Rats were exposed to a 14-day CVS protocol, while being concurrently treated daily with either 7-NI (30 mg/kg) or fluoxetine (10 mg/kg). Fluoxetine and 7-NI prevented the increase in immobility in the FST induced by CVS and reduced plasma corticosterone concentration in stressed rats. Both these treatments also prevented the CVS-evoked reduction of the depressor response to vasodilator agents and baroreflex changes. Fluoxetine and 7-NI-induced cardiovascular changes independent of stress exposure, including cardiac autonomic imbalance, increased intrinsic heart rate and vascular sympathetic modulation, a reduction of the pressor response to vasoconstrictor agents, and impairment of baroreflex activity. Altogether, these findings provide evidence that fluoxetine and 7-NI have similar effects on the depression-like state induced by CVS and on cardiovascular function.

  9. Association Between Variants in Arsenic (+3 Oxidation