Bibliografie tematiche / High Oxidation State of Copper

Letteratura scientifica selezionata sul tema "High Oxidation State of Copper"

Autore: Grafiati

Pubblicato: 22 giugno 2024

Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili

Scegli il tipo di fonte:

Consulta la lista di attuali articoli, libri, tesi, atti di convegni e altre fonti scientifiche attinenti al tema "High Oxidation State of Copper".

Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.

Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.

Articoli di riviste sul tema "High Oxidation State of Copper":

Kondo, Yasumitsu. "Behaviour of Copper and Nickel during High Temperature Oxidation of Steel Containing Them". Materials Science Forum 522-523 (agosto 2006): 53–60. http://dx.doi.org/10.4028/www.scientific.net/msf.522-523.53.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Copper and nickel are accumulated in steels when steel scrap is used as steel sources. It is well known that copper causes hot shortness problem and nickel suppresses the effect of copper. In this paper, the behaviour of copper and nickel during oxidation is investigated. Steels containing copper and nickel were oxidized and the distribution of copper and nickel in the scale was examined. It was found that copper is not only enriched at the scale/metal interface but also exists in upper magnetite layer as a state of solid solution and along grain boundaries of the wustite layer as metal phase. From these results an assumption has been proposed that the liquid copper migrates from the scale/metal interface to the magnetite layer along the grain boundaries. On the other hand, nickel enriched in steel side near the scale/metal interface with copper. The metal particles containing nickel and copper remain inside the scale. Nickel also has an effect of the uneven scale/metal interface formation.

Stadt, Michael Georg, Michael Nelhiebel, Silvia Larisegger e Guenter Fafilek. "In-Situ Raman Spectroscopy of Defined Copper Oxide Surfaces Formed by Electrochemically Controlled High-Temperature Oxidation". ECS Meeting Abstracts MA2023-01, n. 46 (28 agosto 2023): 2490. http://dx.doi.org/10.1149/ma2023-01462490mtgabs.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

The oxidation processes of copper are of great importance since its occurrence leads to various problems, both in further processing and in operation of electronic devices and other technical applications. Extensive research on the thermal oxidation of copper has demonstrated that temperature and oxygen partial pressure affect the formation of oxides, oxidation rates and the chemical composition. In this work powerful electrochemical methods for controlled oxidation are presented, where the oxygen partial pressure on the metal surface can be varied over a range of 10-25 to 100 bar in a single experiment. A specific arrangement of the setup extends its capabilities to enable in-situ Raman spectroscopy measurements of the produced oxide. Controllable oxidation states are achieved in a solid-state electrochemical cell by polarizing a copper sample in contact with a single crystal of yttria-stabilized zirconia, which is conductive for oxygen ions at high temperatures. Optical transparency of the single crystal allows the Raman laser to pass through the crystal to measure the copper oxide formed on the copper-electrolyte interface. Cyclic voltammograms contain kinetic and thermodynamic information about the oxidation processes. Thus, the various oxidation reactions are controlled by the potential that corresponds to the oxygen partial pressure, while the current measures the rate of layer growth as well as the thickness of the oxide layer. In situ Raman measurements allow more detailed analyses of the oxides. The combined data will be used to build a model for oxide layer growth, with particular attention to the defect chemistry of the copper oxide.

Anamaria, Imre, Augustin Mot e Radu Silaghi-Dumitrescu. "Exploring the possibility of high-valent copper in models of copper proteins with a three-histidine copper-binding motif". Open Chemistry 10, n. 5 (1 ottobre 2012): 1527–33. http://dx.doi.org/10.2478/s11532-012-0069-3.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

AbstractAn important function of many copper-containing proteins is activation of O2 and subsequent substrate oxidation. The Cu (III) oxidation state is generally considered to be less accessible because of the highly positive Cu (III)/Cu (II) redox potentials with typical amino acid ligands. Here, we employ density functional (DFT) calculations to explore to what extent copper (III) may be accessed in a biologically-relevant coordination environment around a mononuclear copper center, by breaking the oxygen-oxygen bond in a copper-(hydro) peroxide complex. In agreement with previous findings by Solomon and co-workers on copper models with related coordination patterns, the formally high-valent copper complex produced by O-O bond cleavage appears to harbor both oxidizing equivalents on the ligands. The potential energy surface for such a reaction reveals that with the three-histidine binding motif at the copper, O-O bond cleavage is not impossible, but rather disfavored thermodynamically.

Bera, J. K., A. G. Samuelson e J. Chandrasekhar. "Structure and energetics of high oxidation state copper fragments: Anab initio study". Proceedings / Indian Academy of Sciences 108, n. 3 (giugno 1996): 333. http://dx.doi.org/10.1007/bf02870100.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Kowalska, J., e C. S. Gopinath. "Mapping of Copper Oxidation State Using High Pressure X-Ray Photoelectron Spectroscopy". Acta Physica Polonica A 125, n. 4 (aprile 2014): 1065–66. http://dx.doi.org/10.12693/aphyspola.125.1065.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Costa, Gabriel F., Maria Rodrigues Pinto, Igor Messias, Joao Junior, Nirala Singh e Raphael Nagao. "Tracking Copper Oxidation State during Nitrate Electrochemical Reduction Reaction". ECS Meeting Abstracts MA2023-01, n. 39 (28 agosto 2023): 2300. http://dx.doi.org/10.1149/ma2023-01392300mtgabs.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

The synthesis of ammonia via Haber-Bosch process, obtained from nitrogen catalytic hydrogenation, was a great revolution for humankind that allowed mass production of food with the availability of fertilizers.1 However, it caused a disturbance in the global nitrogen cycle due to the production of ammonia from a non-reactive source (N2), fixing 108 tons of nitrogen into reactive species per year.2 Among nitrogenous contaminants, nitrate is the main pollutant of wastewater and the most oxidized species, being accumulated in the ecosystems.2 Besides that, because of the need of H2 as reactant, the current ammonia production emits 500 million tons of carbon dioxide per year, making ammonia the largest CO2 emitting chemical process.1 Finding sustainable alternatives to restore the nitrogen cycle without compromising ammonia production and consequently food supply is urgently needed.1,3 In this context, nitrate electrochemical reduction reaction (NO3RR) could be a sustainable way to produce ammonia, removing a pollutant from wastewater and helping ammonia decarbonization.2,3 Finding a catalyst that presents high electrochemical performance, high availability, and good stability is still challenging. Among transition metals, copper has the fastest rate-determining step of nitrate reduction to nitrite, offering the highest electrocatalytic kinetics and exchange current densities for NO3RR.4 In addition to metallic copper, its oxides are also attracting attention for catalytic NO3RR.5–13 Different nanomaterials that combine copper metallic and oxide phases have been reported in the literature for ammonia synthesis, with Faradaic efficiencies up to 98%.4 This enhancement is attributed to the fact that Cu2O requires lower activation energy to *NH2O hydrogenation, enabling the faster formation of *NH2OH at catalyst surface.13 Our preliminary results show that there are also synergistic enhancements of Cu and Cu2O, i.e., a prepared mixture of Cu and Cu2O is more active than either compound alone. Herein, we investigate structural and compositional changes at a Cu/Cu2O nanocomposite after and during NO3RR.14 Our findings suggest that under the potentials in which ammonia production from NO3RR takes place, Cu2O is also being reduced to Cu. Figure 1a presents linear sweep voltammetries (LSV) measurements with and without nitrate. LSV obtained in the absence of nitrate (black line) shows a peak related to Cu2O reduction (centered in -0.2 V vs. RHE). In the presence of nitrate (red line), the onset potential is around -0.1 V vs. RHE, from which a cathodic current takes place until -0.8 V vs. RHE. It indicates that Cu2O starts to reduce close to the onset potential for NO3RR. We evaluated the catalyst performance from -0.2 to -0.6 V vs. RHE and the highest faradaic efficiency (66 ± 7%) for NH3 was obtained at -0.4 V vs. RHE (Figure 1b). Then, the composite was ex-situ characterized with spectroscopic and microscopic techniques before and after an 1h-electrolysis at -0.4 V vs. RHE. Though X-ray photoelectron spectroscopy, we show that copper oxidation state changes after potentiostatic electrolysis experiments at -0.4 V vs. RHE (Figures 1c and 1d), where the satellite peak related to Cu2O disappears. Significant structural changes were detected with atomic force microscopy (Figures 1e and 1f), evidenced by the change of the average roughness from 222.5 to 173.1 nm. In-situ Raman spectroscopy was employed to track copper oxidation state during NO3RR. Cu2O has some characteristic peaks at Raman spectra: 150 cm-1 related to infrared active mode F1u (Τ15), 520 cm-1 related to Raman allowed mode 3T’25(F 2g) and 630 cm-1 related to infrared active mode F1u (Τ15).15 The spectra obtained (Figure 1g) showed that these peaks disappear at a less negative potential than the window that ammonia production from NO3RR takes place (-0.2 V vs. RHE), which is in accordance with LSV results, indicating that Cu2O reduces at a more positive potential than nitrate. These results suggest that higher activity for nitrate reduction could be associated with the formation of defects at composite structure, which will be evaluated later with kinetic studies. This work shows strong experimental indicatives that copper oxide is not stable at the potential window employed to ammonia production from NO3RR, although its reduction can induce some defects at copper structure that enhances the catalytic performance. These findings provide important clues towards designing new copper-based materials for electrochemical reduction of nitrate to ammonia. Figure 1

Zelinka, Samuel L., Grant T. Kirker, George E. Sterbinsky e Keith J. Bourne. "Oxidation states of copper in preservative treated wood as studied by X-ray absorption near edge spectroscopy (XANES)". PLOS ONE 17, n. 1 (27 gennaio 2022): e0263073. http://dx.doi.org/10.1371/journal.pone.0263073.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Copper is a common component in wood preservatives and is used to protect the wood against fungal degradation. Previous research has shown that the Cu++ oxidation state provides the best wood protection, and Cu++ is widely believed to be the oxidation state of most copper within treated wood. A recent study using X-ray absorption near edge spectroscopy (XANES) reported high amounts of Cu+ in wood that had been in contact with corroded fasteners. This study uses XANES to examine the copper oxidation states in wood treated with several different wood preservatives as a function of time after treatment. In contrast with previous literature which focused on the fixation reaction in the first few hours after treatment, this paper examines the oxidation state of Cu in treated wood at longer times (up to 1-year) after treatment. The results showed in nearly all cases, Cu was in the Cu++ oxidation state to within the measurement uncertainty. Cu XANES patterns taken approximately 1-year after treatment showed no discernable differences between preservative systems, indicating that regardless of the starting treatment the final Cu speciation is the same within one year. The results confirm previously held beliefs about the Cu oxidation states in wood and give further insights into the corrosion mechanism of metals embedded in treated wood.

Yang, Peng, Xingye Guo, Dingyong He, Zhen Tan, Wei Shao e Hanguang Fu. "Selective Laser Melting of High Relative Density and High Strength Parts Made of Minor Surface Oxidation Treated Pure Copper Powder". Metals 11, n. 12 (23 novembre 2021): 1883. http://dx.doi.org/10.3390/met11121883.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Pure Copper (Cu) is very difficult to prepare using selective laser melting (SLM) technology. This work successfully prepared the pure Cu with high relative density and high strength by the SLM technology using a surface oxidation treatment. The gas-atomized pure Cu powder was used as the feedstock in this work. Before the SLM process, the pure Cu powder was initially handled using the surface oxidation treatment to coat the powder with an extremely thin layer of Cu2O. The SLMed highly dense specimens contain α-Cu and nano-Cu2O phases. A relationship between the processing parameters (laser power (LP), scanning speed (SS), and hatch space (HS)) and density of Cu alloy in SLM was also investigated. The microstructure of SLMed Cu consists of fine grains with grain sizes ranging from 0.5 to ~30 μm. Tensile testing and detailed microstructural characterization were performed on specimens in the as-SLMed and pure copper state specimens. The mechanical property experiments showed that the specimens prepared by SLM technology containing nano-oxide phases had higher yield strength and tensile strength than that of other SLM-built pure copper. However, the elongation was remarkably decreased compared to other SLM-built pure copper, due to the fine grains and the nano-oxides.

Uhlmann, Eckart, Julian Polte, Jan Streckenbach, Ngoc Chuong Dinh, Sami Yabroudi, Mitchel Polte e Julian Börnstein. "High-Performance Electro-Discharge Drilling with a Novel Type of Oxidized Tool Electrode". Journal of Manufacturing and Materials Processing 6, n. 5 (1 ottobre 2022): 113. http://dx.doi.org/10.3390/jmmp6050113.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Electro-discharge drilling is a key technology for manufacturing sophisticated nozzles in a broad range of automotive and aerospace applications. The formation of debris in the working gap leads to arcs and short circuits on the lateral surface when state-of-the-art tool electrodes are used. As a result, limited drilling depth, increased linear tool wear, and the conicity of boreholes are still challenges. In this work, a new approach for the passivation of the lateral surface of copper tool electrodes by oxidation is shown. The comparison with state-of-the-art tool electrodes showed a reduction in the erosion duration by 48% for machining hardened steel. Promising improvements could be achieved by the thermal oxidation of the tool electrodes with the aim of increasing the electrical resistivity of the lateral surface of the tool electrode. However, due to the loss of strength, the high oxide layer thickness, and the partial delamination of the oxide layer, further comprehensive investigations on the influence of the oxidation temperature need to be conducted. Future adjustments with lower oxidation temperatures will be carried out.

Loucks, Robert R., Gonzalo J. Henríquez e Marco L. Fiorentini. "Zircon and Whole-Rock Trace Element Indicators of Magmatic Hydration State and Oxidation State Discriminate Copper Ore-Forming from Barren Arc Magmas". Economic Geology 119, n. 3 (1 maggio 2024): 511–23. http://dx.doi.org/10.5382/econgeo.5071.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Abstract To meet surging requirements of copper for the green energy revolution, minable resources subequal to all copper production in history must be found in the next two decades. We show that trace elements in zircon and whole-rock samples that are diagnostic of unusually high-pressure magmatic differentiation and high hydration state and oxidation state of their parent silicate melt are effective for discriminating copper sulfide-ore-productive arc magmas from infertile arc magmas. Tests on our database of 5,777 zircons from 80 igneous complexes, including 2,220 zircons from ore-generative intrusions in 37 major porphyry and high-sulfidation epithermal Cu(-Au-Mo) deposits worldwide, demonstrate that our magmatic copper fertility discriminants apparently perform equally well in intraoceanic arcs, continental margin arcs, and continental collision orogens of Ordovician to Quaternary age. That performance consistency means that the tectono-magmatic controls on development of magmatic-hydrothermal copper ore-forming fertility are essentially the same in all those plate-convergence settings. The ratio Ce/√(U × Ti) in zircon is a quantitative indicator of the relative oxygen fugacity of the silicate melt and its sulfur-carrying capacity. The ratio of the europium anomaly to ytterbium in granitoid melts and zircon is an uncalibrated but empirically useful indicator of the melt’s hydration state and ability to provide chloride-complexed metals to exsolving hydrothermal fluids. Plots of (EuN/Eu*)/YbN vs. Ce/√(U × Ti) in zircon are remarkably effective for discriminating igneous complexes, arc segments, and time intervals within them that can generate and are likely to host magmatic-hydrothermal Cu(-Au-Mo) ore deposits. Arrays of cognate zircons on such plots have slopes that vary with pressure-dependent chlorinity of exsolving fluid and its efficacy in scavenging CuCl from the melt. Our zircon indicators of Cu metallogenic fertility are applicable to detrital as well as in situ zircons and can assist with ore discovery in watersheds upstream from a sediment sampling site. We formulated a composite zircon copper fertility index (ZCFI) that can be applied to each microbeam spot analysis—ZCFI = 104 (EuN/EuN*)/YbN + 5 Ce/√(Ui × Ti)—and substantially decreases the number of zircon analyses needed for reliable prospectivity assessment in a detrital grain population, thereby making this watershed-scale exploration tool cost-competitive with other methods of geochemical exploration.

Più fonti

Tesi sul tema "High Oxidation State of Copper":

Wang, Guanqi. "Etat d'oxydation élevé des complexes de cuivre de type galactose oxydase pour l'oxydation biomimétique de l'alcool". Electronic Thesis or Diss., Université Grenoble Alpes, 2023. http://www.theses.fr/2023GRALV106.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

La galactose oxydase (GOase), une métallo-enzyme contenant du cuivre, est l'un des biocatalyseurs les plus étudiés pour l'oxydation enzymatique des glucides. Le mécanisme couramment accepté implique la forme oxydée clé (GOaseox), dans laquelle une unité glucidique (galactose) se lie au site équatorial (libre) et subit une déprotonation, suivie d'un arrachage d'atome d'hydrogène par un radical et d'un transfert d'électron supplémentaire, conduisant ainsi à la formation du produit final, l'aldéhyde, et à la réduction de la GOase. En raison de leur potentiel pour des oxydations catalytiques hautement sélectives, des modèles moléculaires du site actif de la GOase dérivés de bases de Schiff encombrées ont été développés. Cette approche biomimétique passe par la synthèse de complexes Cu(II)-phénol servant de pré-catalyseurs, qui subissent ensuite une oxydation à un électron pour devenir la forme "active" du catalyseur. Une question cruciale demeure : quels sont les facteurs qui déterminent si l’oxydation est centrée sur le ligand, produisant des radicaux Cu(II)-phénoxyle, ou vers le métal, formant des espèces Cu(III)-phénolate ? Malgré des efforts importants, une réponse définitive à cette question reste elusive.L'objectif de cette thèse est de développer des ligands redox-actifs afin de mieux comprendre les facteurs qui influencent le site d’oxydation du complexe de cuivre correspondant. La stratégie consiste à incorporer des fonctions chimiques stabilisant l'un ou l'autre tautomère de valence (Cu(II)-radical phénoxyle et Cu(III)-phénolate) et à étudier leur impact. À cet effet, plusieurs complexes ont été synthétisés et caractérisés par spectroscopie et électrochimie. Les activités catalytiques ont également été évaluées sur divers substrats contenant des groupes hydroxyle. Enfin, des calculs de chimie quantique (DFT) ont été réalisés pour aider à élucider les mécanismes catalytiques et à mieux comprendre les caractéristiques des différents complexes
Galactose Oxidase (GOase), a copper-containing metallo-enzyme, is one of the most studied biocatalysts for the enzymatic oxidation of carbohydrates. The consensus mechanism involves the key oxidized form (GOaseox), in which an the carbohydrate substrate (galactose unit) binds to the equatorial (free) site and is subsequently deprotonated. It undergoes hydrogen atom abstraction by the radical and further electron transfer to give the final product aldehyde and the reduced form of the GOase. Due to the potential for highly selective catalytic oxidations, the development of small-molecular models of the GOase active site has been carried out. Notably, sterically hindered schiff bases, which stand as one of the most representative mimics, have garnered significant attention. This biomimetic approach has extended to encompass other strategies. Within this framework, a range of Cu(II)-phenol complexes, serving as pre-catalysts, have been synthesized, subsequently undergoing one-electron oxidation to yield the "active" catalyst form. A central question then arises: What factors determine whether the oxidation pathway proceeds toward the ligand, resulting in the formation of Cu(II)-phenoxyl radicals, or toward the metal, giving rise to the Cu(III)-phenolate species? Despite substantial efforts, a definitive answer to this question has yet to be obtained.The aim of this thesis is to develop redox-active ligands aimed at understanding the factors affecting the oxidation state of copper, able to catalyze the oxidation of an alcohol into an aldehyde. The strategy is to include chemical functions that can stabilize either valence tautomer (Cu(II)-phenoxyl radical and Cu(III)-phenolate) and study their effect. For that purpose, several complexes were synthesized and characterized by different ways to understand their properties. The catalytic activities were also tested against different families of substrates comprising hydroxyl functions. Finally, quantum chemistry (DFT) calculations have been carried to help understand the characteristics of different complexes and elucidate of the catalytic mechanisms at work

King, Lawrence. "High oxidation state group VI imido metallasiloxanes". Thesis, Queen Mary, University of London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369235.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Monaghan, Dermot. "High rate unbalanced magnetron sputtering of thick films of ultra-fine brained OFHC copper and copper alloys". Thesis, University of Salford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336163.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

McFadzean, Belinda Julie. "The kinetics and associated equilibria of high oxidation state osmium complexes". Thesis, Nelson Mandela Metropolitan University, 2007. http://hdl.handle.net/10948/732.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

The reduction of osmium tetroxide by a series of alcohols was studied spectrophotometrically. The reaction was observed to occur in two steps, unlike previously reported studies on this reaction. The identities of both reactants and products were established via a range of techniques. Equilibrium and kinetic data were gathered and reaction models were evaluated using equilibrium and kinetic modelling software. The following complexation reaction model emerged that simulates both the equilibrium and kinetic data. Os(VIII) + RCH2OHOs(VI) + RCHO2 Os(VIII) + Os(VI)k+2k1Complexk-2 Conditional rate constants and equilibrium constants were generated. Rate constants for the alcohol reactions were correlated with the Taft σ* constant. The ρ* value obtained (-1.4) is consistent with a hydride transfer mechanism coupled with synchronous removal of the hydroxyl proton. The identity of the osmium(VIII)-osmium(VI) complex has been suggested. Thermodynamic parameters were also reported. The rate constants for benzyl alcohol and 2-chloroethanol deviated from those predicted by the Taft plot. An explanation of enhanced resonance effects is offered for benzyl alcohol and an alternative reaction mechanism, involving proton abstraction, is offered for 2-chloroethanol. The reaction of the oxidation products of alcohols, namely ketones, with osmium tetroxide produced rate constants that were, perhaps surprisingly, far larger than those of the alcohols. A reaction mechanism for the oxidation of the ketones is suggested, which involves the enolate ion as the reactive starting reagent.

Pearson, Stephen. "High oxidation state carbene complexes for C-H bond activation catalysis". Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/7570.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Chapter one is an introduction to the less common coordination and oxidation chemistry of palladium; complexes containing Pd-OR, Pd-NR2 and those in the oxidation states of +IV. An outline of PdII/IV catalysed ligand-directed oxidative functionalisation is also included. Chapter two covers the design and synthesis of a range of tethered N-heterocyclic carbene (NHC) complexes of Pd. In addition, the syntheses of a number of new tethered NHC ligands are described. The use of Density Functional Theory (DFT) to model the complexes in this thesis was explored. Chapter three describes the synthesis and characterisation of PdIV halide complexes. The relevance of these compounds to PdII/IV catalysed ligand-directed oxidative functionalisation is explored. DFT was used to probe the reaction pathway for N-bromosuccinimide and iodobenzene dichloride. Chapter four examines reactions with oxidants used to form C-O and C-C bonds. The reaction pathway for iodobenzene diacetate was investigated using DFT. Chapter five contains experimental details and characterising data for the compounds reported.

Dann, Sandra Elizabeth. "Preparation and characterisation of high oxidation state compounds of transition metals". Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241254.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Benham, Emmanuel Jakob. "Actinide chemistry : high oxidation-state uranium fluoride and fluoride halide complexes". Thesis, University of Leicester, 1992. http://hdl.handle.net/2381/33962.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

The preparation of UF5 has been re-investigated in detail and it has been shown that the most reliable synthetic route is a novel reaction in which UF6 is interacted with hexamethyldisiloxane at room temperature. The pure UF5 produced has been employed in an investigation of the reactions of UF5.nCH3CN and UF5.nTPPO with trimethylsilylchloride which have been claimed to yield compounds of the type UFxC15-x.nCH3CN (0?x?5 and n = 1,2) and UFxC15-x.nTPPO (TPPO = (C6H5)3PO, 0?x?5 and n = 1,2). In the process of these studies a large number of products were obtained as single crystals and the single-crystal X-ray structures of the novel compounds, [UF4.TPPO]2F, [(UF3.3TPPO)2]2+ 2[UF6]-, cis-UO2Cl2.2TPP0 and ?-trans- UO2Cl2.2TPPO have been obtained. Attempts have been made to elucidate the infrared and e.s.r. spectra of these compounds in order to try to understand the nature of the chemical reactions which give rise to them. Efforts to prepare a mixed bromide fluoride of uranium (VI) have yielded only uranium pentafluoride or uranium tetrafluoride. The preparations of UF5.SbF5.L (L = CH3CN and TPPO) and UF5.2SbF5.5CH3CN were repeated and single crystals were successfully grown for X-ray examination. An attempt to obtain the novel UF5.2SbF5.5TPP0, however, gave inconclusive results.

Spicer, M. D. "Higher oxidation state complexes of group Vb and VIb donor atom ligands : Compounds with cobalt(III) and copper(III)". Thesis, University of Southampton, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382971.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Harbron, S. K. "Studies in the high oxidation state coordination chemistry of osmium and iron". Thesis, University of Southampton, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234174.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Singh, Rojendra. "Cyclopropene polymerization and enyne metathesis catalyzed by high oxidation state molybdenum alkylidenes". Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/43771.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2008.
Vita.
Includes bibliographical references.
Chapter 1. An olefin metathesis reaction between Mo(NAr)(CHCMe2Ph)(OCMe(CF3)2)2 (Ar = 2,6diisopropylphenyl) and trans-i 1,4-divinylbenzene or trans, trans- 1,4-di-buta- 1,3-dienylbenzene (5) results in the formation of bimetallic ROMP initiators [(DME)((CF3)2MeCO)2(ArN)MoCH]2-1,4-C6H4 (DME = 1,2-dimethoxyethane; la) and [(DME)((CF3)2MeCO)2(ArN)MoCHCHCH]2-1,4-C6H4 (6), respectively. An X-ray study of [(THF)((CF3)2MeCO)2(ArN)MoCH]2-1,4-C6H4 (THF = tetrahydrofuran; ib), which is closely related to la, showed it to be the expected bimetallic species in which each end is approximately a trigonal bipyramidal monoadduct of a syn alkylidene with the THF coordinated to the NOO face of the metal trans to the Mo=C bond. Treatment of la with hium-t-butoxide yielded [(Bu-t-O)2(ArN)MoCH]2-1,4-C6H4 (2). Addition of four equivalents of Me3CCH2MgCl to la produced the bimetallic species [(Me3CCH2)2(ArN)MoCH]2- 1,4-C6H4 (3), which upon treatment with 2,6diisopropylphenol generated a diastereomeric mixture of [(DME)(ArO)(Me3CCH2)(ArN)MoCH]2-1,4-C6H4 (4). The solid state structure of 3 revealed a "syn/syn" bimetallic species related to lb. In solution two resonances can be observed in the alkylidene region of the 1H NMR spectra for the "syn/anti" isomer of la, Ib, 2, 3, 4 and 5. The total amount of the "syn/anti" isomer varies between 4 and 20% of the total. Bimetallic species la, 2, and 6 initiate at both ends upon addition of less than ten equivalents of 4,5-dicarbomethoxynorbornadiene (DCMNBD),and afford homopolymers of DCMNBD and methyltetracyclododecene (MTD) in a living fashion. MALDI-TOF mass spectra of ferrocene-containing homopolymers have been obtained that are consistent with the polymerization process being living.
(cont.) Triblock copolymers MTDxDCMNBDyMTDx were prepared by adding y equivalents of DCMNBD to the bimetallic ROMP initiators followed (after consumption of DCMNBD) by 2x equivalents of MTD. These triblocks were shown to be of relatively high purity (free of homopolymer and diblock copolymer) and to have a relatively low polydispersity index. Chapter 2 A series of monomers with side chain liquid crystals (SCLCs) were synthesized for ring opening metathesis polymerization (ROMP). The liquid crystals (LCs) used were 4hydroxybenzoic acid 4-methoxyphenyl ester (MPOB-H), which is known to exhibit a nematic liquid crystalline phase, and biphenyl-4-carboxylic acid 4-(1butoxycarbonylethoxy)phenyl ester (BPP4-H), which is known to exhibit a smectic phase. The side chains differed in spacer length, spacer type, and the nature of the LC. Monomers were polymerized using a bimetallic ROMP initiator [(Bu-t-O)2(ArN)MoCH]2-1,4-C6H4 (where Ar = 2,6-diisopropylphenyl); both homopolymers and ABA type triblock copolymers, where the B block is the LC functional monomer, and A is methyltetracyclodocene (MTD) were prepared. The polymers displayed unimodal peak distributions with polydispersities < 1.22. Incorporation of a polyoxyethylene spacer decreased the glass transition temperature (Tg) of the polymer block to -25 from +20 TC, the Tg when an alkyl spacer was used. Although no distinct LC phase was observed with the polyoxyethylene spacer when MPOB was used, use of BPP4 in conjunction with a polyoxyethylene spacer displayed a distinct liquid crystalline transition. Polymers with an alkyl spacer exhibited liquid crystalline behavior and good phase segregation on the basis of differential scanning calorimetry and small-angle X-ray scattering studies.
(cont.) Chapter 3. Molybdenum imido alkylidene complexes supported by 2,6-diisopropylphenyl, 2,6dimethylphenyl, 1-adamantyl, or 2-trifluorophenyl that contain relatively electronwithdrawing phenolate (pentafluoro), binaphtholate (3,3'-bis(9-anthracenyl), 3,3'bispentafluorophenyl, or 3,3'-bis(3,5-bis(trifluoromethyl)phenyl)) or biphenolate (3,3'-ditert-butyl-5,5'-bistrifluoromethyl-6,6'-dimethyl-1,1'-biphenyl) ligands have been prepared to be tested in olefin metathesis reactions. A series of new monomeric pyrrolide complexes, Mo(NR)(CHCMe2R')(2,5-dimethylpyrrolide)2 (where R' = Me or Ph) and Mo(NAd)(CHCMe2Ph)(2,4-dimethylpyrrolide)2, were also synthesized and treated with alcohols, biphenols or binaphthols in order to generate Mo(NR)(CHCMe2Ph)(diolate) species. In several cases the new alkylidene complexes could be prepared only through reaction of two equivalents of pentafluorophenols or an equivalent of binaphthol (3,3'bis(pentafluorophenyl)binaphthol or 3,3'-bis(3,5-bis(trifluoromethyl)phenyl binaphthol) with a bis(2,5-dimethylpyrrolide) complex. The pyrrolide approach can be employed either to isolate catalysts on a preparative scale or to generate catalysts in situ. Several simple preliminary ring-closing metathesis reactions show that the new complexes are catalytically competent. Chapter 4. Living ring opening metathesis polymerization of cyclopropenes using Mo(NAr)(CHCMe2R)(O-t-Bu)2 (where R = Me; la or R = Ph; ib) and Mo(NAr)(CHCMe2Ph)(OCMe(CF3)2)2 (2) has been achieved. The polydispersity indices of the polymers generated are recorded to be < 1.10 for la and lb based on gel permeation chromatography (GPC). Living polymerization of 3-methyl-3phenylcyclopropene (MPC) by t-butoxide derived molybdenum imido alkylidene initiators is utilized in the synthesis of block copolymers.
(cont.) Diblock copolymers MPCPxDCMNBDy (where DCMNBD = 2,3- dicarbomethoxynorbornadiene and x and y are the number of equivalents of MPC and DCMNBD, respectively) were prepared in quantitative yield with unimodal peak distribution via sequential addition of monomers to the initiator 1b. Triblock copolymers MPC100MEMC100MPCoo0 and MTDiooMEMCIooMTDjoo were prepared using [(O-t-Bu)2(ArN)MoCH]2-1,4-C6H4 (IC) as an initiator. The block copolymers revealed good phase segregation based on the differential scanning calorimetry (DSC). ROMP of MPC by molybdenum imido alkylidene initiators containing electron-withdrawing diolates resulted in highly tactic polymers as determined by 'H and 13C NMR spectroscopy. IR spectroscopy of all MPCl00 revealed absorptions at 963 and/or 982 cm-1 of approximately equal intensity that are most consistent with a trans structure. Chapter 5. Addition of one equivalent of ROH to Mo(NAr)(CHCMe2Ph)(2,5-dimethylpyrrolide)2 (Ar = 2,6-diisopropylphenyl) in diethyl ether or THF yielded Mo(NAr)(CHCMe2Ph)(OR)(2,5-dimethylpyrrolide) species where R = (CH3)3C (1), (CH3)2CH (2), Ar (3), (CF3)2CH (4), (CF3)2MeC (5), (Bu-t-O)3SiO (6) or C6F50 (7). Treatment of an equivalent of PMe3 to 5 resulted in the formation of (Me3P)Mo(NAr)(CHCMe2Ph)(OCMe(CF3)2)(PyrMe) (Me3P-5), which showed trans binding of PMe3 with respect to 2,5-dimethylpyrrolide ligand as determined by the 'H NOESY spectrum. The solid state structure of 3 depicts a psuedo-tetrahedral geometry around the metal center with the 2,5-dimethylpyrrolide ligand bound rq' to the metal cener.
(cont.) Complexes 1-6 show rapid reaction when treated with one atmosphere of ethylene and catalyze ring-closing metathesis reactions. Hetereogenous analogs of 6, Mo(NAr)(CHCMe2Ph)(PyrMe)(OSisurf) (10a), Mo(NAd)(CHCMe2Ph)(PyrMe)(OSisurf) (10b) and Mo(NArF)(CHCMe2Ph)(PyrMe)(OSisurf) (10c) (Ad = 1-adamantyl and ArF = 2trifluoromethylphenyl) showed great enhancement in the catalytic activity when employed in self-metathesis of propene and ethyloleate. Ring-closing enyne metathesis catalyzed by 1 - 6 leads to cyclic products that arise through initial addition of the triple bond to a methylene species (initially neophylidene) to yield an cC- or a 3-substituted metallacyclobutene intermediate.
by Rojendra Singh.
Ph.D.

Più fonti

Libri sul tema "High Oxidation State of Copper":

Whitfield, Pamela Stephenie. Chemical and diffraction studies of the copper oxidation state in cuprate superconductors. Birmingham: University of Birmingham, 1997.

Cerca il testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Barrera, Gabriel Plascencia. High temperature oxidation of copper and copper aluminium alloys: Impact on furnace side wall cooling systems. 2004.

Cerca il testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Gluckman, Sir Peter, Mark Hanson, Chong Yap Seng e Anne Bardsley. Copper in pregnancy and breastfeeding. Oxford University Press, 2015. http://dx.doi.org/10.1093/med/9780198722700.003.0024.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Copper is an essential trace mineral with a central role in oxidation#amp;#x2013;reduction reactions. It is involved in connective tissue formation and disulphide bonding of keratin. Clinical deficiency for copper is uncommon but has been increasing in prevalence, resulting from malnutrition or lack of trace metals in the food source, even in Western diets. Secondary copper deficiency can be induced by excess intake of zinc or iron and is sometimes seen in individuals taking supplements of these minerals. Copper requirements are increased in pregnancy, and suboptimal supply may have adverse effects on developing tissues and organ systems including the lung, skin, bones, and immune system. Despite the increased need, supplementation is generally not recommended in pregnancy. An increased intake of foods high in copper, such as nuts, and a proportionate lowering of low-copper foods (e.g. fats/oils) may be advisable in women with potentially marginal copper status.

Capitoli di libri sul tema "High Oxidation State of Copper":

Schuller, Ivan K., D. G. Hinks, J. D. Jorgensen, L. Soderholm, M. Beno, K. Zhang, C. U. Segre, Y. Bruynseraede e J. P. Locquet. "Copper Oxidation States, Vacancy Ordering and Their Effect on High Temperature Superconductivity". In Novel Superconductivity, 647–52. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4613-1937-5_73.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Nishiyama, Yoshitaka, e Nobuo Otsuka. "The Role of Copper in Resisting Metal Dusting of Ni-Base Alloys". In High-Temperature Oxidation and Corrosion 2005, 581–88. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-409-x.581.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

El-Saadani, Mohamed, Hermann Esterbauer, Günther Jürgens, Mohamed El-Sayed, Ahmed Nassar, Mohamed Goher e Anton Holasek. "Copper and Copper-Nicotinic Acid Complexes Mediated Oxidation of High Density Lipoprotein". In Oxygen Radicals in Biology and Medicine, 381–85. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4684-5568-7_59.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Lim, Byeong Soo, M. J. Jin, Si Yon Bae e Dong Bok Lee. "The Oxidation and High Temperature Fatigue of P23 Alloy". In Solid State Phenomena, 31–38. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/3-908451-15-9.31.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Kondo, Yasumitsu. "Behaviour of Copper and Nickel during High Temperature Oxidation of Steel Containing Them". In High-Temperature Oxidation and Corrosion 2005, 53–60. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-409-x.53.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Shekhter, Dr Leonid N., Dr Corby G. Anderson, Daniel G. Gribbin, Esra Cankaya-Yalcin, Joseph D. Lessard e Larry F. McHugh. "Looping Sulfide Oxidation™Process for Anode Copper Production". In 4th International Symposium on High-Temperature Metallurgical Processing, 37–44. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118663448.ch5.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Chen, Feng, Zhiqiao Yan e Tao Wang. "Effects of Internal Oxidation Methods on Microstructures and Properties of Al2O3 Dispersion-Strengthened Copper Alloys". In High Performance Structural Materials, 1–8. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-0104-9_1.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Morawitz, H., e V. Z. Kresin. "Combined Phonon-Acoustic Plasmon Theory of High-Tc Copper Oxides". In Springer Series in Solid-State Sciences, 376–81. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-84345-7_72.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Raveau, B., F. Deslandes, C. Michel, M. Hervieu, G. Heger e G. Roth. "The Solid State Chemistry of Mixed Valence Copper Oxide High Tc Superconductors". In High-T c Superconductors, 3–12. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4899-0846-9_1.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Rogers, Michelle M., e Shannon S. Stahl. "N-Heterocyclic Carbenes as Ligands for High-Oxidation-State Metal Complexes and Oxidation Catalysis". In N-Heterocyclic Carbenes in Transition Metal Catalysis, 21–46. Berlin, Heidelberg: Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/978-3-540-36930-1_2.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Atti di convegni sul tema "High Oxidation State of Copper":

Asadiankouhidehkordi, Golnoush, Andre C. Liberati, Fadhel Ben Ettouil e Christian Moreau. "Inner Diameter High-Velocity Air Fuel (ID-HVAF) Spraying of Copper, Compared to Cold Spray". In ITSC 2023. ASM International, 2023. http://dx.doi.org/10.31399/asm.cp.itsc2023p0531.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Abstract As a supersonic solid-state deposition process, Cold Spray (CS) has a unique role among other thermal spray techniques as it uses compressed and heated gas to accelerate particles to a critical velocity. CS can be an expensive process, especially when helium is used as a processing gas. In recent thermal spray developments, High-Velocity Air Fuel (HVAF) has taken a specific place in terms of providing dense and strong coatings similar to CS, but also coatings with less oxidation than High- Velocity Oxy-Fuel (HVOF). In contrast to these techniques, HVAF uses a mixture of fuel and air, instead of pure oxygen as in HVOF, to accelerate particles. Therefore, HVAF appears as a relatively cheaper and environmentally friendly alternative for the deposition of a wide variety of materials. The aim of this research is to produce fully dense copper coatings with limited oxidation using an inner diameter (ID) HVAF system and to compare the microstructure with CS copper coatings. Coating microstructures, surface roughness, and microhardness are studied using different characterization methods such as Scanning Electron Microscopy (SEM). Through this paper, the influence of both spray processes, CS and ID-HVAF, on the deposition of copper coatings is discussed. Cross-sectional studies of different coatings show a fairly dense microstructure for CS and ID-HVAF coatings. Moreover, it is discussed how the copper coating properties can change upon modifying the spray parameters.

Webb, Ralph L., Jin Wook Paek e David Pickrell. "Very High Performance Thermal Interface Material and Attachment Technology". In ASME 2003 International Electronic Packaging Technical Conference and Exhibition. ASMEDC, 2003. http://dx.doi.org/10.1115/ipack2003-35253.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

This paper provides an update on work at Penn State University on advanced thermal interface material (TIM) and attachment technology. The TIM concept consists of a “Low Melting Temperature Alloy” (LMTA) bonded to a thin copper substrate. The present work includes analytical modeling to separate the interface resistance (Rint) into “material” and “contact” resistance. Modeling indicates that contact resistance accounts for 1/3 of the interface resistance (Rint). Additional alloys have been identified that have thermal conductivity approximately three-times those identified in the previous 2002 publication. Thermal degradation of the LMTA TIM was also observed in the present work after extended thermal cycling above the melting point of the alloy. Possible mechanisms for this degradation are oxidation and contamination of the alloy layer rather than the inter-metallic diffusion. Use of the high thermal conductivity alloys, and soldered contact surfaces will provide very low Rint as well as minimizing the thermal degradation. It appears that Rint as small as, or less than, 0.005 cm2-K/W may be possible. Description of the modified Penn State TIM tester is provided, which will allow measurement of Rint = 0.01 cm2-K/W with less than 30% error.

Katcher, Kelsi M., Timothy C. Allison, Michael Marshall, Yuin Jin, Chansun Lim e Sungho Chang. "Design of a Cooled sCO2 Combustion Test Rig for Steady-State Kinetics Testing". In ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/gt2021-04122.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Abstract Within the research area of sCO2 power cycles, the direct-fired oxy-combustion cycle is of great interest because the inherent carbon capture makes it a desirable option for clean power generation. In order to better understand the combustion kinetics of the direct-fired cycle in sCO2, a laboratory-scale combustion test rig was designed. The design and thermal-mechanical analysis of the combustor test rig for steady-state open-loop combustion testing is presented. The test rig is designed for operating conditions of 265 bar and full-scale oxy-combustion temperatures. The test rig incorporates a laser igniter and modular fully premixed injector to enable testing with step- or swirl-style flame holders. The rig also employs an existing dense-phase sCO2 pump to provide a closed-loop high-flow cooling circuit to enable cost-effective short-lead manufacturing of liner and pressure casing components. Finally, the test rig’s multi-zone copper alloy C18150 liner design minimizes thermal stresses and allows for independent control of dilution flow in each zone to vary combustion temperatures. Planned measurements include exit temperature profile and chamber dynamic pressures. The sensitivity of CO oxidation and other reaction rates to temperature will be indirectly evaluated using post-combustion gas sampling for comparison with combustion simulations.

Wenting Zhao, Jiechen Wu, Anmin Hu, Ming Li e Dali Mao. "An investigation into copper oxidation behavior". In High Density Packaging (ICEPT-HDP). IEEE, 2010. http://dx.doi.org/10.1109/icept.2010.5582339.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Xiangquan Fan, Techun Wang, Yuqi Cong, Binhai Zhang e Jiaji Wang. "Oxidation study of copper wire bonding". In High Density Packaging (ICEPT-HDP). IEEE, 2010. http://dx.doi.org/10.1109/icept.2010.5582431.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Lee, K. I., K. I. Min, S. K. Joo, K. G. Rha e W. S. Kim. "Characteristics of the Oxidation Barrier Layers for Copper Metallization". In 1994 International Conference on Solid State Devices and Materials. The Japan Society of Applied Physics, 1994. http://dx.doi.org/10.7567/ssdm.1994.c-11-4.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Tatham, D. R., Liang-Kuei Chou e K. A. Abboud. "High-oxidation state salts of BEDT-TTF". In International Conference on Science and Technology of Synthetic Metals. IEEE, 1994. http://dx.doi.org/10.1109/stsm.1994.835519.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Rotteger, Chase, e Scott Sayres. "TUNABLE EXCITED STATE DYNAMICS OF NEUTRAL COPPER OXIDE CLUSTERS WITH SIZE AND OXIDATION". In 2023 International Symposium on Molecular Spectroscopy. Urbana, Illinois: University of Illinois at Urbana-Champaign, 2023. http://dx.doi.org/10.15278/isms.2023.6998.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Iwaki, Chikako, Daigo Kittaka, Toshihiro Yoshii, Motoshige Yagyu, Masato Okamura, Masashi Tanabe e Fumihiko Ishibashi. "Development of Hydrogen Treatment System in Severe Accident: Part 2 — Study on Reaction Characteristic of a Hydrogen Processing Unit". In 2016 24th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/icone24-60917.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

In the course of a severe accident, a large amount of hydrogen gas is generated by a metal-water reaction in a PCV (Primary Containment Vessel) of Light Water Reactors. Although the filter vent of gas mixture, which includes hydrogen and steam, is an effective method for the accident management of BWR that prevents the PCV overpressure, the filter vent at the early stage of severe accident may cause releasing radioactive material to environment. We have been developing the hydrogen treatment system to prevent excessive pressure without PCV vent and releasing radioactive material to environment. We focus on the oxidation-reduction reaction of metal oxides with high reaction rates, for the hydrogen treatment system. Metal oxide material would be an effective device under low-oxygen conditions like PCV of BWR. The hydrogen treatment system mainly consists of a hydrogen processing unit, a blower and pipes. The hydrogen treatment unit has a lot of reaction pipes in which metal oxides are filled. Some fundamental chemical experiments which we have done have revealed that copper oxides (CuO) rapidly react with hydrogen to form cupper (Cu). Their results show that metal oxides are effective as hydrogen treatment elements. On the other hand, there are few evaluations for the characteristics of hydrogen treatment unit. The dependency of hydrogen treatment performance on gas temperature, hydrogen concentration and pressure is investigated in the present study. We conducted experiments using a test section with one reaction pipe, which simulated a hydrogen processing unit. The processing materials granulated CuO, MnO2 and Co3O4 with 2mm diameter were used. Gradual increase of processing material temperature in the test section was observed along the gas streams caused by oxidation-reduction reaction after the mixing gases were supplied. Consequently, the hydrogen concentration at the outlet of the test section decreased with time. The increase of the hydrogen reaction rate was also observed with increase of gas temperature, hydrogen concentration and pressure. We have developed the thermal-chemical model of hydrogen processing unit from these experiment results, and confirmed that the model could predict the characteristics of a hydrogen processing unit qualitatively.

Lee, W. L., J. L. Zhang, S. Y. Wang, M. L. Tsai, G. L. Luo e C. H. Chien. "Time-Dependent Selective Oxidation by Low Pressure Oxidation on High-Ge-Content SiGe". In 2018 International Conference on Solid State Devices and Materials. The Japan Society of Applied Physics, 2018. http://dx.doi.org/10.7567/ssdm.2018.ps-1-22.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Rapporti di organizzazioni sul tema "High Oxidation State of Copper":

Chacon, L. C. The synthesis, characterization and reactivity of high oxidation state nickel fluorides. Office of Scientific and Technical Information (OSTI), dicembre 1997. http://dx.doi.org/10.2172/335167.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Lucier, George Michael. Synthesis, structure, and reactivity of high oxidation state silver fluorides and related compounds. Office of Scientific and Technical Information (OSTI), maggio 1995. http://dx.doi.org/10.2172/101247.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Shen, Ciping. Preparations and characterizations of novel graphite-like materials and some high oxidation state fluorine chemistry. Office of Scientific and Technical Information (OSTI), novembre 1992. http://dx.doi.org/10.2172/10174522.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Tawfik, Aly, Deify Law, Juris Grasis, Joseph Oldham e Moe Salem. COVID-19 Public Transportation Air Circulation and Virus Mitigation Study. Mineta Transportation Institute, giugno 2022. http://dx.doi.org/10.31979/mti.2021.2036.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

COVID-19 may have forever changed our world. Given the limited space and air circulation, potential infections on public transportation could be concerningly high. Accordingly, this study has two objectives: (1) to understand air circulation patterns inside the cabins of buses; and (2) to test the impact of different technologies in mitigating viruses from the air and on surfaces inside bus cabins. For the first objective, different devices, metrics and experiments (including colored smoke; videotaping; anemometers; pressure differentials; particle counts; and 3D numerical simulation models) were utilized and implemented to understand and quantify air circulation inside different buses, with different characteristics, and under different operating conditions (e.g. with windows open and shut). For the second objective, three different live prokaryotic viruses were utilized: Phi6, MS2 and T7. Various technologies (including positive pressure environment inside the cabin, HEPA filters with different MERV ratings, concentrated UV exposure with charged carbon filters in the HVAC systems, center point photocatalytic oxidation technology, ionization, and surface antiviral agents) were tested to evaluate the potential of mitigating COVID-19 infections via air and surfaces in public transportation. The effectiveness of these technologies on the three live viruses was tested in both the lab and in buses in the field. The results of the first objective experiments indicated the efficiency of HVAC system designs, where the speed of air spread was consistently much faster than the speed of air clearing. Hence, indicating the need for additional virus mitigation from the cabin. Results of the second objective experiments indicated that photocatalytic oxidation inserts and UVC lights were the most efficient in mitigating viruses from the air. On the other hand, positive pressure mitigated all viruses from surfaces; however, copper foil tape and fabrics with a high percentage of copper mitigated only the Phi6 virus from surfaces. High-temperature heating was also found to be highly effective in mitigating the different viruses from the vehicle cabin. Finally, limited exploratory experiments to test possible toxic by-products of photocatalytic oxidation and UVC lights inside the bus cabin did not detect any increase in levels of formaldehyde, ozone, or volatile organic compounds. Implementation of these findings in transit buses, in addition to the use of personal protective equipment, could be significantly valuable for protection of passengers and drivers on public transportation modes, possibly against all forms of air-borne viruses.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Plouffe, A., D. Petts, I M Kjarsgaard e M. Polivchuk. Laser ablation inductively coupled plasma mass spectrometry mapping of porphyry -related epidote from south-central British Columbia. Natural Resources Canada/CMSS/Information Management, 2023. http://dx.doi.org/10.4095/331671.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

The microscopic composition of thirteen samples of epidote related to porphyry Cu mineralization was mapped using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) at the Geological Survey of Canada. The objective of this research is to improve the indicator mineral method of mineral exploration in glaciated terrains by utilizing the trace element composition of epidote. Six bedrock samples from porphyry Cu deposits of south-central British Columbia (Gibraltar, Mount Polley and Woodjam), three bedrock samples from the Nicola Group located close (&lt;2 km) from the intrusions host of porphyry mineralization and afar (12 km), and four epidote grains from two till samples, one at Gibraltar and a second one at Mount Polley, were analyzed. Backscattered electron (BSE) images and the LA-ICP-MS maps show an heterogeneous distribution of Fe and Al in epidote following complex and mottled patterns and consistent zoning typically with high Fe and low Al concentrations in the core progressing to low Fe and high Al concentrations in the rim. Trace elements are heterogeneously distributed in epidote following the Fe/Al zoning in some samples. Evidence of late infiltration of trace elements (e.g. Cu, Zn, and REE) along fractures in epidote is observed in some samples. The variability in epidote composition is thought to be related to the changing conditions during its crystallization including oxidation state, pH, oxygen fugacity, fluid composition, temperature and pressure. Multiple LA-ICP-MS spot analyses need to be conducted on this mineral to fully evaluate its composition as an indicator mineral of porphyry Cu mineralization.