Academic literature on the topic 'Redox condition'
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Journal articles on the topic "Redox condition"
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Olander, D. "Redox condition in molten fluoride salts." Journal of Nuclear Materials 300, no. 2-3 (February 2002): 270–72. http://dx.doi.org/10.1016/s0022-3115(01)00742-5.
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Güler, Taki. "Redox behavior of galena in alkaline condition." Ionics 24, no. 1 (June 9, 2017): 221–27. http://dx.doi.org/10.1007/s11581-017-2172-0.
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Su, Yan, Yong Sheng Zhao, Rui Zhou, Xiao Wang, and Sheng He. "Research on Natural Attenuation of BTEX and Changes of Redox Environment in the Process." Advanced Materials Research 183-185 (January 2011): 715–19. http://dx.doi.org/10.4028/www.scientific.net/amr.183-185.715.
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Natural attenuation of BTEX and characteristics of the water in the study are researched in this paper. The study not only obtain the attenuation rules of BTEX over time, but also the rules of the redox materials of the contaminated groundwater over time. From the study, we reach conclusion that the redox conditions is changed with the increasing pollution of BTEX and the oxidation condition changes into reducing condition. With the changing of the redox condition, there take place a variety of redox reactions. The materials of oxidation, such as O2, NO3-, Fe3+and SO42-, are transformed into reduction materials, such as NO2-, Fe2+, S2- and so on. In this process, the components of BTEX are degradated by micro-organisms which using the oxidation materials as electron acceptors.
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Madukwe, Henry Y. "Source-Area Weathering, Composition and Paleo-Redox Condition of Stream Sediments from Ijero-Ekiti, Nigeria." International Journal of Trend in Scientific Research and Development Volume-1, Issue-5 (August 31, 2017): 446–65. http://dx.doi.org/10.31142/ijtsrd2365.
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Tokunaga, Kohei, Tomoya Uruga, Kiyofumi Nitta, Yasuko Terada, Oki Sekizawa, Shinsuke Kawagucci, and Yoshio Takahashi. "Application of arsenic in barite as a redox indicator for suboxic/anoxic redox condition." Chemical Geology 447 (December 2016): 59–69. http://dx.doi.org/10.1016/j.chemgeo.2016.10.016.
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Rouwane, Asmaa, Malgorzata Grybos, Isabelle Bourven, Marion Rabiet, and Gilles Guibaud. "Waterlogging and soil reduction affect the amount and apparent molecular weight distribution of dissolved organic matter in wetland soil: a laboratory study." Soil Research 56, no. 1 (2018): 28. http://dx.doi.org/10.1071/sr16308.
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The release of dissolved organic matter (DOM) from wetland soils is an important pathway for the input of organic compounds into adjacent aquatic environments. In the present study we investigated, under controlled laboratory conditions, the quantity and quality of DOM released from a wetland soil subject to waterlogging and reducing conditions. Three soil redox conditions (oxic, moderately reducing and advanced reducing) were distinguished based on nitrate, ferrous ions and sulfate concentrations in soil solution. Under each redox condition, the quantity (dissolved organic carbon (DOC), humic substances and peptides plus proteins (P-PN) and quality (aromaticity; specific ultraviolet absorbance at 254 nm (SUVA254nm)) and apparent molecular weight (aMW) distribution) of DOM were investigated. The results showed that soil redox condition affects the amount and properties of mobilised DOM. The rate of DOM release and SUVA254 values were highest during the transition from oxic to moderately reducing conditions, whereas both stabilised during progression to advanced reducing conditions. In addition, the mobilised DOM is expected to be more reactive because of an increase in polar substituents in aromatic structures between oxic and moderately reducing conditions. During the development of moderately reducing conditions, dissolved humic substances increased significantly, whereas their aMW distribution (between 500 and 6000 ) remained constant for each of the three different redox conditions. In contrast, the quantity of dissolved P-PN remained low and steady under the three redox conditions, whereas the aMW distribution of protein-like and microbial by-product-like compounds decreased during the development of reducing conditions (aMW of compounds between 100 and >100 000).
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Yang, Rui, Sheng He, Xiao Wang, Qinhong Hu, Dongfeng Hu, and Jizheng Yi. "Paleo-ocean redox environments of the Upper Ordovician Wufeng and the first member in lower Silurian Longmaxi formations in the Jiaoshiba area, Sichuan Basin." Canadian Journal of Earth Sciences 53, no. 4 (April 2016): 426–40. http://dx.doi.org/10.1139/cjes-2015-0210.
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A study of paleo-ocean redox environments is important for understanding the deposition of black shale and has practical implications for shale gas exploration. Here, we selected a total of 52 shale samples from JY1 Well, the first shale gas well of commercial exploitation in China, to analyze the redox conditions of Upper Ordovician Wufeng (O3w) and the first member in lower Silurian Longmaxi shale (S1l1) in the Jiaoshiba area. Abundant pyrite framboids are observed in these units, with average framboid diameters ranging from 3.1 to 4.7 μm and maximum diameter about 10 μm. Analyses of redox-sensitive trace elements suggest the redox environment has evolved from an anoxic condition in the bottom of Member A to a dysoxic condition in the top of Member A, and to a dysoxic–oxic environment in Members B and C. Graptolite and radiolarian are discovered in these shale samples, indicating an oxygenated seafloor, which seems to be contradictory to the results from pyrite framboids and redox-sensitive trace elements. This contradiction is explained as follows: when the shale was deposited, the sedimentation was dominated by euxinic conditions; however, some oxygen may also occasionally migrate to the bottom water due to oxygen-deficient environment, deglaciation, and (or) strong upwelling of nutrient-enriched seawater, while the limited oxygen and anoxic environment is favorable for the preservation and accumulation of organic matter. Combined with the geological characteristics and redox conditions, Member A, especially the shales at the bottom of Member A, is expected to be the most favorable shale gas reservoir in the Jiaoshiba area.
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Gwon, Oh Hun, Jong Yun Kim, Seok-Ju Kang, Hye Ryung Byun, and Young-Jun Yu. "Surface Condition and Conductance of Graphene in Redox Process." Applied Science and Convergence Technology 30, no. 6 (November 30, 2021): 183–85. http://dx.doi.org/10.5757/asct.2021.30.6.183.
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Wiyoto, Wiyoto, Sukenda Sukenda, Enang Harris, Kukuh Nirmala, and Daniel Djokosetiyanto. "Water Quality and Sediment Profile in Shrimp Culture with Different Sediment Redox Potential and Stocking Densities Under Laboratory Condition." ILMU KELAUTAN: Indonesian Journal of Marine Sciences 21, no. 2 (June 2, 2016): 65. http://dx.doi.org/10.14710/ik.ijms.21.2.65-76.
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Sediment quality has been considered as one of the prime factors influencing the environment quality that support maximum shrimp production.The aim of the study was toevaluate the effects of sediment redox potential and shrimp stocking density on the profile of some sediment and water quality parameters. Two factors randomized factorial design was applied, with stocking density (60 and 120 shrimps.m-2) as the first variable and sediment redox potential (-65 mV, -108 mV and -206 mV) as the second variable. Some significant changes in TP, total Mn, and total S concentrations in the sediment were observed after the experimentation (P<0.05). Sediment redox potential significantly affected the dissolved oxygen, TAN, NO2, NO3, and H2S concentrations in the water. Whereas shrimp stocking density affected all water quality parameters except H2S concentration. Significant interactions between redox potential and stocking densities were observed in the nitrite and alkalinity concentrations. The significant effects of both shrimp density and redox potential on the sediment and water parameters in particular those that are known to directly affect the shrimp welfare (e.g. oxygen, ammonia, nitrite and H2S) indicate that these variables are of important aspects in shrimp pond management. Furthermore, the results clearly showed that -206mV redox potential significantly reduced the dissolved oxygen concentration in the sediment-water interface and increased the generation of H2S in water column. Thereby, this redox potential level is not advisable for shrimp culture system. Keywords: redox potential, stocking density.
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Ramprasath, Tharmarajan, Allen John Freddy, Ganesan Velmurugan, Dhanendra Tomar, Balakrishnan Rekha, Vemparthan Suvekbala, and Subbiah Ramasamy. "Context-Dependent Regulation of Nrf2/ARE Axis on Vascular Cell Function during Hyperglycemic Condition." Current Diabetes Reviews 16, no. 8 (September 11, 2020): 797–806. http://dx.doi.org/10.2174/1573399816666200130094512.
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: Diabetes mellitus is associated with an increased risk of micro and macrovascular complications. During hyperglycemic conditions, endothelial cells and vascular smooth muscle cells are exquisitely sensitive to high glucose. This high glucose-induced sustained reactive oxygen species production leads to redox imbalance, which is associated with endothelial dysfunction and vascular wall remodeling. Nrf2, a redox-regulated transcription factor plays a key role in the antioxidant response element (ARE)-mediated expression of antioxidant genes. Although accumulating data indicate the molecular mechanisms underpinning the Nrf2 regulated redox balance, understanding the influence of the Nrf2/ARE axis during hyperglycemic condition on vascular cells is paramount. This review focuses on the context-dependent role of Nrf2/ARE signaling on vascular endothelial and smooth muscle cell function during hyperglycemic conditions. This review also highlights improving the Nrf2 system in vascular tissues, which could be a potential therapeutic strategy for vascular dysfunction.
Dissertations / Theses on the topic "Redox condition"
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Igboamalu, Tony E. "Kinetic studies of Cr(VI) reduction in an indigenous mixed culture of bacteria in the presence of As(III)." Diss., University of Pretoria, 2014. http://hdl.handle.net/2263/46240.
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An indigenous mixed culture of bacteria collected from a Wastewater Treatment Plant (Brits,
North West Province, South Africa), biocatalytically reduced Cr(VI) in the presence of
As(III). Both the reduced chromium (Cr(III)) and the oxidised arsenic (As(V)) readily form
amorphous hydroxides that can be easily separated or precipitated from the aqueous phase as
part of the treatment process. Treatment of Cr(VI) and As(III) before disposal of wastewater
is critical since both compounds are known to be carcinogenic and mutagenic at very low
concentrations, and acutely toxic at high concentrations.
Batch experiments were conducted to evaluate the rate of Cr(VI) reduction under anaerobic
condition in the presence of its co-contaminant As(III) typically found in the groundwater
and mining effluent. Results showed near complete Cr(VI) reduction under initial Cr(VI)
concentrations up to 70 mg/L in a batch amended with 20 mg/L As(III). However, increasing
Cr(VI) concentrations up to 100 mg/L resulted in the inhibition of Cr(VI) reduction activity.
Further investigation was conducted in a batch reactor amended with 70 mg/L Cr(VI)
concentration at different As(III) concentrations ranging from 5-70 mg/L to evaluate the
effect of varying As(III) concentration on Cr(VI) reduction efficiency. Results showed that
Cr(VI) reduction efficiency increased as As(III) concentrations increased from 5-40 mg/L.
However, further increase in As(III) concentration up to 50 mg/L resulted in incomplete
Cr(VI) reduction and decrease in Cr(VI) reduction efficiency. These results suggest that the
rate of Cr(VI) reduction depends on the redox reaction of As(III) and As(V) with Cr(VI).
Moreover, the inhibitory effect observed at high Cr(VI) and As(III) concentration may also be attributed to the dual toxicity effect of Cr(VI) and As(III) on microbial cell. From the
above batch kinetic studies lethal concentration of Cr(VI) and As(III) for these strains was
evaluated and established.
Initial evaluation of the bacteria using 16S rRNA partial sequence method showed that cells
in the mixed culture comprised predominantly of the Gram-positive species: Staphylococcus
sp., Enterobacter sp., and Bacillus sp. The biokinetic parameters of these strains were
estimated using a non-competitive inhibition model with a computer programme for
simulation of the Aquatic System “AQUASIM 2.0”.
Microbial reduction of Cr(VI) in the presence of As(III) was further investigated in
continuous-flow bioreactors (biofilm reactor) under varying Cr(VI) loading rates. The reactor
achieved Cr(VI) removal efficiency of more than 96 % in the first three phases of continuous
operation at lower Cr(VI) concentration ranging from 20-50 mg/L. However, 20 % decrease
in Cr(VI) removal efficiency was observed as Cr(VI) concentration increase up to 100 mg/L.
The reactor was able to recover from Cr(VI) and As(III) overloading phase after establishing
the resilient nature of the microorganism. Similarly to the batch reactor studies the overall
performance of the reactor also demonstrated that the presence of As(III) greatly enhance
Cr(VI) reduction in a bioreactor. This was evident by near complete removal of Cr(VI)
concentration up to 50 mg/L. The basic mass balance expressions on Cr(VI) along with the
non-competitive inhibition model were used to estimate the biokinetic parameters in the
continuous flow bioreactor system.
Cr(VI) reduction efficiency along the longitudinal column was also evaluated in this study.
Results showed that Cr(VI) efficiency increased as Cr(VI) concentration travels along the
longitudinal column. Other important factors such as oxygen and pH during biological Cr(VI)
reduction in the presence of As(III) oxidation were also evaluated.Dissertation (MEng)--University of Pretoria, 2014.
tm2015
Chemical Engineering
MEng
Unrestricted
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Pham, Thu Ha. "Modifications de la physiologie de la levure Saccharomyces cerevisiae par des changements d’environnements redox et gazeux en condition de brasserie." Dijon, 2008. http://www.theses.fr/2008DIJOS001.
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Modifier les flux métaboliques chez Saccharomyces cerevisiae présente un intérêt non seulement pour l’étude du métabolisme cellulaire mais aussi pour le développement de nouvelles technologies en industries des boissons alcoolisés afin d’améliorer les performances de la production, baisser le niveau d’alcool et développer des sous-produits valorisables. En condition de brasserie, l’utilisation de gaz a permis de modifier l’environnement redox de S. Cerevisiae au cours de la fermentation alcoolique. Les environnements gazeux et redox extrêmes ont altéré partiellement la croissance ainsi que la morphologie cellulaire. Cependant, la performance de la fermentation a été améliorée de 13 à 15% sous atmosphères gazeuses (hydrogène et hélium). Le profil des métabolites de fermentation y compris des composés d’arômes a été différemment modifié par l’effet de gaz et du redox (augmentation de la production de glycérol, de succinate et de certains alcools supérieurs importants pour la flaveur de la bière ; diminution de la quantité des certains esters aromatiques). Au cours d’une conservation à 4°C en condition nutritive limitée, la survie de S. Cerevisiae issue des cultures sous gaz a été améliorée de 55% grâce à sa teneur importante en glycogène intracellulaire et son adaptation morphologique. Ces résultats apportent un éclairage nouveau sur le comportement physiologique de la levure S. Cerevisiae face à des changements d’environnements gazeux et redox. Ils ouvrent également des perspectives pour l’étude de l’application des gaz et du redox dans les industries utilisant S. CerevisiaeModifying metabolic fluxes in Saccharomyces cerevisiae presents an interest both for cellular metabolism studies and the development of new technologies in alcohol beverage-related industries. This will permit to improve the production performances, to lower the alcohol level and to develop by-products of interest. During brewing fermentation, the use of gases modified the redox environment of S. Cerevisiae. The gaseous environments and extreme redox conditions altered partially the growth as well as the cellular morphology. However, the fermentation performances were improved up to 13-15% in gaseous environments (hydrogen and helium). Fermentation metabolite profiles including aroma compounds were modified differently by the effect of gas and redox (increasing in the production of glycerol, succinate and some higher alcohols important for the flavour of beer; decrease in the levels of some flavour-active esters). During storage at 4°C under limited nutritive condition, the survival of S. Cerevisiae cultivated with gas was improved up to 55%. This is due to its high intracellular glycogen content and its morphological adaptation. These results provide new information on the physiological behaviour of S. Cerevisiae in gaseous and redox environments. They also offer perspectives for the studying of gas and redox applications in S. Cerevisiae-related industries
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Sansotta, Stefano [Verfasser], Dirk [Akademischer Betreuer] Zahn, Dirk [Gutachter] Zahn, and Bernd [Gutachter] Meyer. "Molecular Simulations Study of Silver Precipitation from Aqueous Solution and on Silica Substrate. Control of Shape and Charge via Redox Condition / Stefano Sansotta ; Gutachter: Dirk Zahn, Bernd Meyer ; Betreuer: Dirk Zahn." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2020. http://d-nb.info/1219303453/34.
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Xiong, Yijun. "Phosphorus cycling under different redox conditions." Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/22045/.
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Phosphorus is a basic but essential nutrient element for life, as a major limiting nutrient, is also important for controlling primary productivity on geological timescales. However, P cycling is highly redox dependent through Earth history. The fate of P cycling in many environments is still not clear. This thesis is to investigate mineralogical controls on P cycling under different redox conditions. New geochemical data is reported in the low sulfate, euxinic Lake Cadagno, Switzerland, to investigate the behaviour of the phosphorus cycle. Sulfide-driven release of phosphorus from organic matter and Fe (oxyhydr)oxide minerals is re-trapped by Fe(II) phosphate to constrain the extent of P recycling, and this process is highly sulfate dependent. New experiments are designed to investigate what minerals control P cycling in the water column under different conditions. With the increase of P, Green rust is transformed to vivianite which shows that P concentrations exert first order controls on the mineralogy of Fe minerals, with strong implications for the availability of dissolved P in the water column. In order to quantify the extent of P cycling versus fixation in the sediments under different redox conditions, mass balance models are made based on 4 key redox scenarios. Analogous to those which were prevalent at various intervals in Earth history, under ancient episodes of ferruginous conditions, low flux of recycled P back to water column is controlled by both P re-uptake by Fe(III) (oxyhydr)oxide and the formation of Fe(II) phosphate. During the mid-Proterozoic and during Phanerozoic, under low sulfate euxinia, the flux of recycled P is constrained by Fe(II) phosphate formation. This study provides supporting evidence to the suggestion that the positive primary productivity feedback is constrained by these processes.
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Masters-Waage, Nicholas. "Redox cycling under nuclear legacy conditions." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/redox-cycling-under-nuclear-legacy-conditions(abb173ad-0a8c-47b9-a2e7-99ea2048d2c2).html.
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Subsurface contamination is common at nuclear sites and it is likely that radioactive wastes will be managed in the long-term via burial in a deep Geological Disposal Facility (GDF). The migration of radionuclides in the geosphere from such sites is a major societal concern. In particular, long-lived, redox-active radionuclides (in the case of this thesis: 99Tc and Np) can migrate over large distances due to their high solubility under oxic conditions. Bioremediation has been proposed as a mechanism to limit the migration of 99Tc and Np in the environment. Here, an electron donor is supplied to the subsurface and soluble Tc(VII) and Np(V) are reduced to poorly soluble Tc(IV) and Np(IV), respectively. Reduction occurs via direct microbial action (termed bioreduction) or through radionuclide reaction with the by-products of microbial metabolism (primarily Fe(II)). Given the ubiquity of microorganisms and Fe in the geosphere, similar reactions can be expected in the deep subsurface surrounding a GDF. Once reduced, the long-term stability of the Tc(IV) and Np(IV) phases will significantly impact migration rates. Oxidative dissolution of Tc(IV)- and Np(IV)-bearing solids has been demonstrated in the literature and can be pervasive, thus questioning the efficacy of bioreduction. However, these studies have been conducted over short time-scales and during a single period of oxidation. Given the long half-life of 99Tc and Np and the ephemeral nature of redox conditions in the subsurface, there is a need to better understand 99Tc and Np biogeochemistry during longer time-scales and across multiple redox cycles. In this thesis, microcosm experiments have been used to address this knowledge gap. Sediment and groundwater used in the microcosms were representative of the Sellafield Ltd. nuclear site. For Tc, three successive redox cycles (reduction followed by oxidation with O2) over 2 years, gradually reduced the extent of Tc remobilisation during oxidation, and molecular scale characterisation of solids revealed that sediment associated Tc was always present as Tc(IV). Further, over time sequential extractions and EXAFS revealed an increased significance of Tc-Fe bonding in the sediment at the expense of TcO2. Despite this, a small but significant fraction of Tc(IV) was also found to be stable in solution during the experiments and XAS and TEM analysis suggested this was Tc(IV) associated with magnetite colloids. In other experiments completed with higher concentrations of bioavailable Fe (added as ferrihydrite to sediments, and in pure culture experiments with Geobacter sulfurreducens), the significance of Tc-Fe bonding was again highlighted, and potential Tc(IV) incorporation into biogenic magnetite was also documented. In experiments with Np, virtually all of the Np(V) added to oxic groundwater was removed to the sediment commensurate with microbially mediated Fe(III) reduction. Further, in systems with elevated bioavailable Fe, Np removal from solution was more extensive. Taken together, the data for Tc and Np reveals critical links between redox-active radionuclides and Fe cycling in sediments over periods of years and across multiple redox cycles. Furthermore, these processes help to predict the long-term fate of radioactive contamination at the Sellafield Ltd. nuclear site and have implications for contaminated land worldwide.
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Brown, Kevin Robert. "Cytochrome c₄ : characterisation, location and effect of growth conditions." Thesis, University of Edinburgh, 1988. http://hdl.handle.net/1842/30037.
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Rupp, Erik C. "Catalytic Dechlorination of Volatile Organic Carbons under Redox Conditions." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/194518.
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Chlorinated hydrocarbons, such as perchloroethylene (PCE) and trichloroethylene (TCE), are persistent environmental hazards, due to improper disposal, affecting groundwater sources located near a variety of industrial processes. As many chlorinated hydrocarbons are suspected carcinogens, there is great interest in developing inexpensive and environmentally sound technologies for the remediation of contaminated sites. Current efforts focus on the use of soil-vapor extraction (SVE) to pass gas phase contaminants through a granular activated carbon bed (GAC), which creates solid toxic waste, and possibly more harmful by-products during GAC regeneration. This research focuses on the use of hydrogen and short-chain alkanes, in combination with oxygen, to promote the conversion of PCE over a Pt/Rh three-way catalyst. The use of both of a hydrocarbon and oxygen creates mixed reducing-oxidizing (redox) conditions. Results indicate that redox conditions result in the complete removal of the target compound and produces primarily CO₂, H₂O and HCl. The process has proven to be most effective near stoichiometric conditions with respect to the reducing and oxidizing agents (2:1 for H₂:O₂ and 1:5 for propane:O₂). Residence times in the reactor are typically on the order of 0.1 to 0.5 seconds and catalyst surface temperatures range from 200 °C to 550 °C, with PCE conversion greater than 99% starting at 450 °C under slightly reducing (H₂:O₂ > 2) conditions. Laboratory results suggest that the catalytic mechanism is a multiple step surface reaction involving the three reactants (H₂/C₃H₈, O₂ and PCE). A mechanism based on Langmuir- Hinshelwood kinetics has been developed in an attempt to model the process. The role of the cerium oxide present in a three-way catalyst on the direct oxidation of perchloroethylene (PCE) has also been explored. Experiments have shown that in the absence of an external oxidizing agent, PCE can be converted over an alumina supported Pt/Rh catalyst. This work hypothesizes that the chlorine atoms in the adsorbed PCE interact with oxygen in oxidized cerium, CeO₂, reducing the cerium and replacing the oxygen atoms to create CeCl₃. This process begins at a catalyst surface temperature of 300 °C and reaches 100% conversion at 400 °C.
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Markelova, Ekaterina. "Interprétation du potentiel redox et évaluation de la mobilité des oxyanions contaminants (As, Sb,Cr) au cours de cycles redox successifs." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAU028/document.
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Cette thèse démontre qu'une approche expérimentale systématique de complexité croissante permet de réévaluer le sens du potentiel redox (EH), et fournit une mise à jour sur l'interprétation de sa valeur dans les assemblages complexes de matrices minérales, des consortiums microbiens, des nutriments et des contaminants sous dynamique, oxydoréduction oscillant conditions. Pour étudier l'utilité des mesures EH dans les systèmes environnementaux saturés d'eau une cascade complète redox 500 à -350 mV (pH ~7.4) a été reproduit dans le laboratoire. Les expériences ont révélé que l'électrode de Pt classique redox répond à des processus microbiens dans une mesure différente en fonction de l'oxygénation et de la présence d'un tampon d'oxydo-réduction physique, chimique et. Les mesures du EH dans des matrices argileuses appauvris dans le tampon redox, tels que le couple électroactif Fe3 + / Fe2 +, par conséquent, se révèlent avoir une utilité limitée. Dans de tels environnements, les couples redox sensible abondantes, cependant, non électroactif, tels que O2 / H2O, CrO42- / Cr (OH) 3, NO3- / NO2- / NH 4 +, Sb (OH) 6- / Sb2O3, et HAsO42 - / H3AsO3 ne pas d'impact mesuré EH. Pour quantifier l'effet de l'oxydation des perturbations sur la mobilité des oxyanions dans la matrice argileuse, j'ai effectué des expériences de traitement par lots sous oscillations redox contrôlées. cycles successifs de conditions oxiques et anoxiques ont été imposées sur les suspensions argileuses modifiées avec un mélange d'oxyde As (V), Sb (V), Cr (VI) et N (V). la mobilité des oxyanions a été étudiée dans des conditions stériles, avec l'addition de carbone organique labile (éthanol), et avec l'addition de microbienne du sol inoculum. Spéciation analyses ont révélé des réactions irréversibles de réduction avec ou sans ajouts d'éthanol. Fraîchement réduite As (III), Sb (III), Cr (III) et N (III) ne sont pas ré-oxydée pendant les périodes subséquentes oxiques démontrant un comportement non-oscillant. Microbiologiquement induit des transformations de réduction a diminué les concentrations aqueuses de Sb et Cr par précipitation, enlevés N par volatilisation, alors préservé Comme dans la solution. En fonction de la diversité microbienne, altérées par l'addition d'inoculum dans le sol, deux types de contaminants imbrications sont caractérisés comme inhibiteurs de réduction et de non-inhibiteurs. Ces données, le représentant de l'environnement souterrain saturé (sous-sol> 20 m), est en outre par rapport à oxyanion mobilité dans l'environnement proche de la surface (la couche arable <0,15 m). Les principales différences entre les systèmes de la couche arable et du sous-sol sont dans la fraction d'oxyhydroxyde Fe-, Mn- et minéraux Al-, la diversité microbienne, pCO2, et la gamme des valeurs EH développées au cours des cycles d'oxydo-réduction. Par exemple, la gamme EH de plus de 900 mV (500 à -300 mV) dans la suspension de la couche arable est opposée à la gamme EH de 100 mV (350-250 mV) dans la suspension du sous-sol. En outre, dans la suspension de la couche arable, fort cycle redox de Fe et Mn coïncide avec la mobilité d'oscillation de As et Sb. Cette corrélation suggère le rôle crucial des minéraux oxyhydroxyde agissant non seulement comme principaux sorbants, mais aussi comme catalyseurs pour des réactions d'oxydation éventuellement contrôlant la réversibilité de la séquestration des contaminants. Par conséquent, appauvri en minéraux oxyhydroxyde, matrice argileuse est révélée environnement propice à la rétention des contaminants, car il peut supporter des oscillations périodiques redox sans libérer les contaminants de retour à la phase aqueuse sur l'échelle de temps expérimentalThis thesis demonstrates that a systematic experimental approach of increasing complexity allows reassessing the meaning of the redox potential (EH), and provides an update on the interpretation of its value in complex assemblages of mineral matrices, microbial consortiums, nutrients, and contaminants under dynamic, redox-oscillating conditions. To study the usefulness of EH measurements in water-saturated environmental systems a full redox cascade from +500 to -350 mV (pH ∼7.4) was reproduced in the laboratory. The experiments revealed that conventional Pt redox electrode responds to physical, chemical, and microbial processes to a different extent depending on oxygenation and on the presence of a redox buffer. The measurements of EH in argillaceous matrices depleted in the redox buffer, such as the electroactive Fe3+/Fe2+ couple, thus, are shown to have limited usefulness. In such environments, the abundant redox-sensitive couples, yet non-electroactive, such as O2/H2O, CrO42-/Cr(OH)3, NO3-/NO2-/NH4+, Sb(OH)6-/Sb2O3, and HAsO42-/H3AsO3 do not impact measured EH. To quantify the effect of oxidizing perturbations on the mobility of oxyanions in the argillaceous matrix, I performed batch experiments under controlled redox oscillations. Successive cycles of oxic and anoxic conditions were imposed on the argillaceous suspensions amended with a mixture of oxidized As(V), Sb(V), Cr(VI), and N(V). Oxyanion mobility was investigated under sterile conditions, with the addition of labile organic carbon (ethanol), and with the addition of soil microbial inoculum. Speciation analyses revealed irreversible reduction reactions with and without ethanol additions. Freshly reduced As(III), Sb(III), Cr(III), and N(III) were not re-oxidized during subsequent oxic periods demonstrating non-oscillating behavior. Microbially induced reduction transformations decreased aqueous concentrations of Sb and Cr via precipitation, removed N via volatilization, while preserved As in the solution. Depending on microbial diversity, altered by the addition of soil inoculum, two types of contaminant interplays are characterized as inhibitory and non-inhibitory reductions. These data, the representative of saturated subsurface environment (subsoil > 20 m), is further compared to oxyanion mobility in the near-surface environment (topsoil < 0.15 m). The key differences between the topsoil and subsoil systems are in the fraction of oxyhydroxide Fe-, Mn-, and Al- minerals, microbial diversity, pCO2, and the range of EH values developed during redox cycles. For example, the EH range over 900 mV (from +500 to -300 mV) in the topsoil suspension is contrasted to the EH range of 100 mV (from +350 to +250 mV) in the subsoil suspension. Furthermore, in the topsoil suspension, strong redox cycling of Fe and Mn is coincident with the oscillating mobility of As and Sb. This correlation suggests the crucial role of oxyhydroxide minerals acting not only as major sorbents, but also as catalysts for oxidation reactions eventually controlling the reversibility of contaminant sequestration. Therefore, depleted in oxyhydroxide minerals, argillaceous matrix is shown to be suitable environment for contaminant retention, as it can stand periodical redox oscillations without releasing contaminants back to the aqueous phase on the experimental time scale
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Gaborieau, Marion. "Caractérisation des conditions redox du manteau terrestre dans différents contextes géodynamiques." Thesis, Université Clermont Auvergne (2017-2020), 2019. http://www.theses.fr/2019CLFAC084.
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Plusieurs études ont permis de mettre en évidence que les basaltes d’arc sont plus oxydés (~ ∆QFM+1.5 ± 1) que les basaltes de rides médio-océaniques (MORB ; ∆QFM-1.2 à ~ ∆QFM). Cependant, l’état redox du manteau sous les arcs est toujours débattu. L’utilisation de différents proxys de la détermination de la fugacité d’oxygène (fO2) sur un même jeu d’échantillons a pour objectif de déterminer plus précisément l’état d’oxydation des magmas, de contraindre l’effet des processus secondaires tels que la différenciation et le dégazage sur leur état d’oxydation et ainsi de mieux caractériser la fO2 des magmas primaires et du manteau supérieur dans les différents contextes géodynamiques. Pour cela, les rapports Fe3+/ΣFe, les coefficients de partage du V entre les liquides silicatés et les olivines (DvOl/Liq) ainsi que les rapports V/Sc et V/Yb ont été déterminés dans des magmas piégés précocement après la fusion du manteau sous forme d’inclusions magmatiques dans des olivines magnésiennes (Fo > 80 %) provenant de différents contextes géodynamiques (i.e. contexte de dorsale médio-océanique, de zone de subduction et de point chaud). La détermination des rapports Fe3+/ΣFe par spectroscopie XANES avec des conditions analytiques permettant d’éviter les processus de photo-oxydation des verres hydratés et par spectroscopie Mössbauer a permis de confirmer que les basaltes d’arc sont plus oxydés que ceux des points chauds (OIB) et des MORB. La corrélation entre les rapports Fe3+/ΣFe et les teneurs en H2O des inclusions magmatiques suggère que la différence d’état d’oxydation serait liée à une variation de l’état d’oxydation du coin de manteau causée par le processus de subduction. De plus, les fO2 obtenues à partir de ces rapports indiquent qu’au sein de la population des magmas d’arc, l’état d’oxydation des magmas est variable d’une zone de subduction à l’autre. Par la suite, une évaluation de l’effet du dégazage des éléments volatils et de la cristallisation fractionnée sur la fO2 des magmas a été menée pour chaque population d’inclusions des différentes localités. Après avoir reconstitué les compositions des liquides magmatiques primaires, leur fO2 a été estimée à partir des différents proxys de la mesure de la fO2. Les résultats obtenus à partir des rapports Fe3+/ΣFe, des coefficients de partage DvOl/Liq et des rapports V/Yb indiquent que les magmas primaires d’arc sont plus oxydés que ceux des rides médio-océaniques et des points chauds. Cependant, les valeurs de fO2 obtenues à partir de ces trois proxys diffèrent. Par ailleurs, la corrélation entre les rapports Fe3+/ΣFe, les fO2 calculées à partir de ces rapports et les teneurs en H2O des magmas primaires suggère que la différence d’état d’oxydation des magmas n’est pas liée à l’effet des processus secondaires. Toutefois, la comparaison entre les rapports Fe3+/ΣFe, les fO2 calculées à partir de ces rapports et les rapports Th/La et Ba/La des magmas primaires ne permet pas d’affirmer que les variations observées seraient liées à l’influence d’un liquide silicaté provenant de la fusion des sédiments recouvrant la plaque plongeante ou d’un fluide aqueux libéré par la plaque au cours de la subduction. A l’opposé, les fO2 obtenues à partir des rapports V/Sc suggèrent que les magmas primaires d’arc ont un état d’oxydation comparable à ceux des MORB et des OIBMany studies have demonstrated that arc basalts are more oxidized (~ ∆QFM+1.5 ± 1) than mid-ocean ridge basalts (MORB; ∆QFM-1.2 à ~ ∆QFM). However, the oxidation state of the sub-arc mantle is still debated. The use of various proxies on the same set of samples aims to determine the oxidation state of magmas, the effects of secondary processes on their oxidation state and to better constrain the fO2 of primary magmas from different geodynamic settings and that of their mantle source. For that purpose, Fe3+/ΣFe ratios, V partition coefficients between silicate melts and olivines (DvOl/Melt) as well as V/Sc and V/Yb ratios were measured in melt inclusions from high-Mg olivines (Fo > 80 %) from subduction zones, mid-oceanic ridges and hot spots. The analysis of Fe3+/ΣFe ratios by XANES spectroscopy using analytical conditions that prevent beam damage during analysis of hydrous glasses and by Mössbauer spectroscopy confirmed that arc magmas are more oxidized than those from hot spots and mid-ocean ridges. A positive correlation between Fe3+/ΣFe ratios and water contents in melt inclusions suggests that the oxidation state recorded in primitive arc magmas is likely to be due to changes in the oxidation state of the mantle beneath arcs because of subduction processes. The calculation of the fO2 from Fe3+/ΣFe ratios also indicates that the range of oxidation state recorded in arc melt inclusions varies from one subduction zone to another. An evaluation of the effects of volatile degassing and differentiation processes on the magmatic fO2 was carried out on each melt inclusion population. fO2 values were then estimated for reconstructed primary melt compositions using the different redox proxies. Results obtained from Fe3+/ΣFe ratios, DvOl/Melt partition coefficients and V/Yb ratios suggest that arc primary magmas are more oxidized than those from hot spots and mid-ocean ridges. However, fO2 values differ from one proxy to another. Furthermore, the positive correlation between the Fe3+/ΣFe ratios, the fO2 calculated from these ratios and the water contents of primary magmas suggests that the difference in the oxidation state of magmas is not due to secondary processes. However, the comparison between the Fe3+/ΣFe ratios, the fO2 values calculated from these ratios and Th/La and Ba/La ratios of primary magmas does not confirm that the observed changes in redox state can be simply linked to the influence of silicate melt or aqueous fluids coming from the slab to the mantle wedge. On the opposite, fO2 values calculated from V/Sc ratios suggest that primary arc magmas are comparable to those from mid-ocean ridges and hot spots
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Smedborn, Pausson Eva. "Chemical Stabilization of Arsenic in Contaminated Soil under Low Redox Conditions." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-72340.
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Remediation techniques for arsenic contaminated soil have previously focused mostly on the surface soil layers where aerobic conditions are prevalent. In this master thesis, chemical stabilization by adding zero-valent iron (Fe(0)) and calcium oxide (CaO) to an arsenic-contaminated soil under low redox conditions have been studied through up-flow percolation tests. Over a time of 2 months, pH, conductivity, redox potential and concentrations of major and minor elements including As, Zn, Cu, Cd, Fe and Ca under both fluctuating and continuous flow were measured. Results indicate that CaO is a very promising amendment to use under conditions of low redox, immobilizing 98% of the As and 50-65% of Zn, Cd and Cr over the 8 weeks of testing, compared to the untreated soil. Copper on the other hand was mobilized by the treatment; but as the concentrations of Cu in the soil was low the increased leaching would in this case not be problematic. The leached water also had a very alkaline pH at 13, while conductivity was relatively high at 6.5 mS cm-1 and the redox potential remained negative throughout the two months. Geochemical modelling indicate that the immobilization of As is most likely controlled by precipitation of Ca-As-complexes as well as ettringite and portlandite. The precipitation of these minerals are controlled by pH, while redox conditions were shown to not be a controlling factor. The alkalinity of the CaO-amended soil was very high and it is expected that the alkaline conditions controlling the immobilization of As will prevail for hundreds of years. Fe(0) that previously has shown good results in stabilizing As under oxidized conditions did not effectively immobilize As under the low redox conditions in this study. Rather, the leaching of As and metals like Cr, Cd, Cu and Zn showed very similar results as the untreated soil. The results signifies the importance of activating the Fe(0) beforehand to allow amorphous Fe-oxides to form to which the metal(loids) can sorb to. In the study it was also observed that a fluctuating groundwater table could have an effect on both untreated and treated soil as wet and dry cycles influenced the leached concentrations of As and many other elements. More As was leached during the dry days in the untreated soil and the soil treated with Fe(0), while the opposite was true for the CaO-treated soil. The results suggests that using CaO as an amendment to treat As-contaminated soil is a method that potentially can be used for soils that have low redox conditions, for example soils below the groundwater table and landfills, although caution should be used in situations with more complex contamination, e.g. where both As and Cu are present.Efterbehandlingsmetoder för arsenikförorenad jord har tidigare fokuserat på ytliga jordlager där syre finns tillgängligt och förhållandena är oxiska. I denna masteruppsats har kemisk stabilisering av arsenik under anoxiska förhållanden i en förorenad jord studerats. I perkolationsförsök över två månader har effekten av två olika kemiska tillsatser, nollvärt järn (Fe(0)) och kalciumoxid (CaO), på utlakningen av halvmetaller och metaller som As, Zn, Cd, Cu och Cr samt påverkan på pH, konduktivitet och redoxpotential undersökts under både fluktuerande och konstanta flöden. Resultaten visar att CaO är en lovande tillsats att använda för kemisk stabilisering av As i jordar som har anoxiska förhållanden. 98% av As immobiliserades jämfört med den obehandlade jorden. Behandlingen med CaO resulterade även i ett stabilt basiskt pH på 13. Konduktiviteten hölls också på en stabil nivå på 6,5 mS cm-1 medans redoxpotentialen varierade en del men var negativ under hela experimentet. Den utlakade koncentrationen av As låg mellan 0.059 och 0.021 mg L-1. CaO immobiliserade även Zn, Cd och Cr med en effektivitet som låg mellan 50-65%, jämfört med den obehandlade jorden. Koppar däremot mobiliserades och lakades ut i större utsträckning; men då Cu-koncentrationen i jorden var låg från början utgör detta inget större problem. Geokemisk modellering indikerade att immobiliseringen av As kontrolleras av pH, men förblev opåverkad av redoxpotentialen. Då alkaliniteten i den CaO-behandlade jorden var hög förväntas de basiska förhållandena som kontrollerar den kemiska stabiliseringen av As att kvarstå under flera hundra år. Tidigare studier har visat att Fe(0) till stor del stabiliserar As under oxiska förhållanden, men under de anoxiska förhållandena i denna studie hade den Fe(0)-behandlade jorden liknande resultat som den obehandlade jorden, både vad gäller utlakning av metaller, pH, konduktivitet och redoxpotential. Detta markerar vikten av att aktivera Fe(0) genom att låta den reagera med syre och vatten i jorden för att bilda amorfa Fe-oxider som (halv)metallerna kan adsorbera till. I detta fall tillsattes inget vatten i förväg, vilket ledde till att det mesta av järnet lakades ut direkt, utan att bilda fler ytor som speciellt As kan binda till. För båda dessa jordar var utlakningen av As två storleksordnar större jämfört med den CaO-behandlade jorden. Studien visade också att en fluktuerande grundvattennivå kan ha en effekt på utlakningen av grundämnen både behandlad och obehandlad jord, då cykler av anoxiska och oxiska förhållanden påverkade koncentrationerna i utlakningsvattnet. Mer As lakades ut under de dagar som hade mer anoxiska förhållanden jämfört med oxiska dagar för den Fe(0)-behandlade jorden och den obehandlade jorden, medans det motsatta var sant för den CaO-behandlade jorden. Resultaten indikerar att CaO har en potential till att användas för att kemiskt stabilisera As i jordar som har låga redox-förhållanden, exempelvis i jordar som är under grundvattenytan och i deponier, men att försiktighet ska användas i jordar som har en mer komplex föroreningssituation, speciellt i jordar som är förorenat av både As och Cu.
Books on the topic "Redox condition"
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Gascoyne, Mel. The evolution of redox conditions and groundwater geochemistry in recharge-discharge environments on the Canadian Shield. Pinawa, Man: Whiteshell Laboratories, 1996.
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Canada. Atomic Energy of Canada Limited. Whiteshell Laboratories. The evolution of redox conditions and groundwater geochemistry in recharge-discharge environments on the Canadian Shield. Pinawa ,Man: Atomic Energy of Canada, 1996.
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Rogers, J. E. Effects of temperature and redox conditions on degradation of chlorinated phenols in freshwater sediments: Project summary. Athens, GA: U.S. Environmental Protection Agency, Environmental Research Laboratory, 1989.
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Jane, Kiringai, ed. Sources of economic growth in Kenya: A redux. Nairobi, Kenya: Kenya Institute for Public Policy Research and Analysis, 2007.
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Encontro da Rede Regional Norte Nordeste de Estudos e Pesquisas sobre a Mulher e Relações de Gênero (8th 1999 Fortaleza, Brazil). Múltiplas trajetórias: Estudos de gênero do 8o. Encontro da REDOR. [Fortaleza, Brazil]: Edições REDOR/NEGIF-UFC, 2001.
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Thomas, Mary Ann. The association of arsenic with redox conditions, depth, and ground-water age in the glacial aquifer system of the northern United States. Reston, Va: U.S. Dept. of the Interior, U.S. Geological Survey, 2007.
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Thomas, Mary Ann. The association of arsenic with redox conditions, depth, and ground-water age in the glacial aquifer system of the northern United States. Reston, Va: U.S. Dept. of the Interior, U.S. Geological Survey, 2007.
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Thomas, Mary Ann. The association of arsenic with redox conditions, depth, and ground-water age in the glacial aquifer system of the northern United States. Reston, Va: U.S. Dept. of the Interior, U.S. Geological Survey, 2007.
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L' Europe communautaire, l'Etat-nation et la société rurale: Essai de sociologie des médiations institutionnelles et organisationnelles (l'exemple du Pays de Redon). Paris: L'Harmattan, 1996.
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Dimancescu, Dan. Romania Redux. Humanitas, 2004.
Find full textBook chapters on the topic "Redox condition"
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Yakushev, Evgeniy. "Redox Conditions." In Encyclopedia of Estuaries, 501–2. Dordrecht: Springer Netherlands, 2015. http://dx.doi.org/10.1007/978-94-017-8801-4_384.
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Takamatsu, Takejiro, Kenji Kashiwaya, and Takayoshi Kawai. "Inorganic Characteristics of Surface Sediment from Lake Baikal: Natural Elemental Composition, Redox Condition, and Pb Contamination." In Long Continental Records from Lake Baikal, 313–27. Tokyo: Springer Japan, 2003. http://dx.doi.org/10.1007/978-4-431-67859-5_20.
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Dalle-Donne, Isabella, Ranieri Rossi, Fabrizio Ceciliani, Daniela Giustarini, Roberto Colombo, and Aldo Milzani. "Proteins as Sensitive Biomarkers of Human Conditions Associated with Oxidative Stress." In Redox Proteomics, 485–525. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2006. http://dx.doi.org/10.1002/0471973122.ch16.
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Go, Young-Mi, Jan Pohl, and Dean P. Jones. "Quantification of Redox Conditions in the Nucleus." In The Nucleus, 303–17. Totowa, NJ: Humana Press, 2008. http://dx.doi.org/10.1007/978-1-60327-461-6_17.
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Nanzyo, Masami, and Hitoshi Kanno. "Inorganic Soil Constituents Sensitive to Varying Redox Conditions." In Inorganic Constituents in Soil, 97–131. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-1214-4_5.
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Altenbach, Alexander Volker, and Maren Gaulke. "Did Redox Conditions Trigger Test Templates in Proterozoic Foraminifera?" In Cellular Origin, Life in Extreme Habitats and Astrobiology, 591–614. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-1896-8_31.
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Clark, Mark H., and Chien-Lu Ping. "Hydrology, Morphology, and Redox Potentials in Four Soils of South Central Alaska." In Aquic Conditions and Hydric Soils: The Problem Soils, 113–31. Madison, WI, USA: Soil Science Society of America, 2015. http://dx.doi.org/10.2136/sssaspecpub50.c7.
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Müller-Simon, Hayo. "Redox-Dependent Glass Properties and Their Control Under Industrial Conditions." In Ceramic Transactions Series, 299–313. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118405949.ch29.
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Wadhwa, Meenakshi. "17. Redox Conditions on Small Bodies, the Moon and Mars." In Oxygen in the Solar System, edited by Glenn J. MacPherson, David W. Mittlefehldt, and John H. Jones, 493–510. Berlin, Boston: De Gruyter, 2008. http://dx.doi.org/10.1515/9781501508509-017.
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Bourg, A. C. M., and J. P. G. Loch. "Mobilization of Heavy Metals as Affected by pH and Redox Conditions." In Biogeodynamics of Pollutants in Soils and Sediments, 87–102. Berlin, Heidelberg: Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-642-79418-6_4.
Full textConference papers on the topic "Redox condition"
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Mannari, Toko, and Takashi Hikihara. "A restricting condition on transient behavior of redox flow battery in phase space." In 2017 IEEE International Telecommunications Energy Conference (INTELEC). IEEE, 2017. http://dx.doi.org/10.1109/intlec.2017.8214148.
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Hashimoto, S., H. Watanabe, T. Sakamoto, T. Kawada, K. Yashiro, J. Mizusaki, K. Kumada, D. Changsheng, K. Sato, and T. Hashida. "The Design and Development of an Evaluation System for Redox Characteristics of Anode Supported SOFCs Using In-Situ Acoustic Emission and Electrochemical Technique." In ASME 2012 10th International Conference on Fuel Cell Science, Engineering and Technology collocated with the ASME 2012 6th International Conference on Energy Sustainability. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/fuelcell2012-91156.
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In this study, a redox evaluation system for anode supported SOFCs using in-situ acoustic emission (AE) and electrochemical technique has been developed. The system consists of a gas blending unit, moisture controlling unit, AE cell evaluation probe, gas cooling exhaust, electrochemical cell test system and AE signal measurement system. The anode supported coin cells, which have the same thickness dimension as practical SOFCs have, can be evaluated under temperature and atmosphere controlled conditions. The oxygen partial pressure in the anodic atmospheres can be gradually controlled from air to reducing atmosphere using the gas blending unit which is connected to 6 gas cylinders. Humidity in the anodic atmospheres can be controlled by moisture controlling unit which consists of 2 bubblers form 0.86% (5°C saturation) up to 80% (94°C saturation). Redox process of the anode can be simulated in this system by controlled three oxidation modes, i.e. O2 gas oxidation, steam oxidation and electrochemical oxidation, which correspond to actual troubles, i.e. gas leakage, degradation of downstream and fuel depletion, respectively. An AE transducer can monitor the cell condition via an inner tube for a guide of exhaust from the cathode. Redox cell test for the anode supported coin cell has been examined at 770°C using this system. After the reduction of the anode substrate in moist H2, current 0.5Acm−2 loaded to the cell. And then H2 gas concentration had been reduced by stages. The cell voltage was down to below −6V after H2 gas concentration was reduced to pH2 = 2%. This drastic cell voltage drop and AE signal generation occurred at the same time. It is considered that Ni re-oxidation with fracture started at this time. Local delamination between anode and electrolyte, and also cracks at the electrolyte and cathode were observed after redox test. It was confirmed that AE sensing is effective for redox evaluation.
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Wang, Yun, and Sung Chan Cho. "Advanced Modeling of the Dynamics of Vanadium Redox Flow Batteries." In ASME 2015 13th International Conference on Fuel Cell Science, Engineering and Technology collocated with the ASME 2015 Power Conference, the ASME 2015 9th International Conference on Energy Sustainability, and the ASME 2015 Nuclear Forum. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/fuelcell2015-49408.
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In this paper, a multi-dimensional dynamic model of vanadium Redox Flow Batteries (RFB) is employed to predict battery performance and internal operating condition during charge and discharge. The model consists of a set of partial differential equations of mass, momentum, species, charges, and energy conservation, in conjunction with the electrode’s electrochemical reaction kinetics. After validated against experimental data for a vanadium RFB, flow field, temperature distribution, and reactant evolution are presented. The developed numerical tool is extremely useful in optimizing RFB design and control.
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Kim, Beom Kyu, Byung Gi Park, Hwa Jeong Han, Ji Hye Park, and Won Ki Kim. "An Effect of Bismuth Ion on the Reduction of Terbium Ion in Molten LiCl-KCl Eutectic Salt." In 2018 26th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icone26-82468.
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A salt waste generated from the pyroprocess contains residual actinides and needs to be purified for recycling of the salt and waste conditioning. A co-reduction process could be considered for removal of residual actinides from the salt waste, which contains lanthanides and residual actinides. In the study, specifically, an effect of Bi(III) ion on the electrochemical reaction of Tb(III) ion was investigated in the molten LiCl-KCl eutectic with BiCl3 and TbCl3 at 773 K using electrochemical techniques of cyclic voltammetry, square wave voltammetry and open circuit chronopotentiometry. Tb(III) has a single redox couple without Bi(III). However, the cyclic voltammograms obtained at tungsten electrode in LiCl-KCl-BiCl3-TbCl3 showed four redox couples. The square wave voltammogram in same condition also showed five reduction peaks. Cyclic voltammogram and square wave voltammogram was resolved to find the accurate peaks for redox reaction. Each peak indicates the formation of Tb-Bi intermetallic compound except Tb(III) reduction peak. From the phase diagram of Tb-Bi, it is inferred that each peak corresponds to TbBi2, TbBi, Tb4Bi3, and Tb5Bi3. The open circuit chronopotentiometry was conducted to estimate Gibbs free energy of formation of Tb-Bi intermetallic compound. The experimental results obtained from three kind of the electrochemical techniques showed that Tb-Bi intermetallic compounds were electrochemically formed under potential of Tb(III) reduction potential by co-reduction of Bi(III) and Tb(III). These results indicate that underpotential deposition by co-reduction could be used for Tb(III) removal from the salt waste with Bi(III).
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Shi, Yu, and Jiyun Zhao. "A Dynamic Model Incorporating the Effects of the Ion Diffusion and Side Reactions for the Vanadium/Air Redox Flow Battery." In ASME 2018 12th International Conference on Energy Sustainability collocated with the ASME 2018 Power Conference and the ASME 2018 Nuclear Forum. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/es2018-7120.
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The vanadium/air redox flow battery working performance will be affected by many factors, including the quality of the membrane used and the working conditions. The crossover rate of vanadium ions for the membrane can determine the capacity due to the ion diffusion and the side reactions. The high reaction temperature for the VARFB also influence the diffusion coefficient. Based on Fick’s Law, by using Arrhenius Equation to predict the temperature effect, and take into consider that the mass balance for each reacting ions and reaction temperature, the dynamic modelling on capacity decay can be developed. Then by using Nernst Equation, the voltage change of VARFB can also be calculated. This dynamic model will predict the concentration change of the battery as a function of time, after benchmarking with the experimental data, this model can compare the performance of the battery with a different order of diffusion coefficient membranes in different working condition. This model can also predict the contacting V2+ concentration to the electrode and catalyst to monitor the working efficiency.
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Alam, Mahboob, GP Gurumurthy, Muguli Tripti, Yoshiki Sohrin, Tsujisaka M, Shotaro Takano, AD Singh, and Komal Verma. "Reconstruction of the late Miocene redox condition in the eastern Arabian Sea at IODP Site U1457 of Laxmi Basin using stable isotopes of molybdenum and tungsten." In Goldschmidt2022. France: European Association of Geochemistry, 2022. http://dx.doi.org/10.46427/gold2022.9184.
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Lee, Dae Hoon, Sejin Kwon, Jin Soo Hwang, and Sang-Eon Park. "Thermochemical Design of a Micro Liquid Monopropellant Rocket With Catalytic Reaction of Hydrogen Peroxide." In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-39193.
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A theoretical and experimental investigation on a design of catalytic reactor of submilimeter scale to be used as a micro propulsion device is described. A micro reactor was fabricated on an aluminum plate and catalyst was prepared on the anodized internal surface of the reactor. The reactor has a height of 1mm and width of 10mm. The height of the reactor is the major constraint when a prototype device is to be fabricated on a wafer by MEMS processing. Thermodynamic properties of product gases from the decomposition process of hydrogen peroxide in contact with perovskite based redox cycling catalyst were measured. A theoretical model was developed to predict the heat and gaseous mass generated from the decomposition process of hydrogen peroxide by using asymptotic approximation of reacting flow in 1-D channel with height of 1mm or less in order to approximate the actual operating condition of propulsion device on a chip. The measured heat transfer coefficients and thermodynamic properties were used in the calculation. As the monopropellant decomposes into water and oxygen, the reaction products are heated. The enhanced heat loss due to the small size of the chamber, however, adversely affected the thermochemical process of decomposition.
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Wang, Wang, Yongliang Hu, Chengguo Guan, and Chuanming Zhou. "Revisting the Early-To-Middle Ediacaran Ocean Redox Conditions." In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.2766.
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Sundaresan, Vishnu Baba, Ryan L. Harne, Travis Hery, and Quanqi Dai. "A Nonlinear, Monolithic Structural-Material System for Vibration Energy Harvesting and Storage." In ASME 2016 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/smasis2016-9304.
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This research introduces an integrated vibration energy harvester and electrochemical energy storage device that can effectively convert ambient vibrations directly into stored electrochemical energy. The electrochemical energy storage device is an electrical double layer capacitor (EDLC) with an ionic redox transistor as its membrane separator. This ‘smart’ membrane separator directly rectifies the electrical energy generated by the transduction from the nonlinear energy harvester, creating an ionic polarization across the membrane separator for storage. This electrochemical gradient can be subsequently used for powering sensor electronics as required in various applications, including structural condition monitoring. The alternating voltage developed by the energy harvester (+/−5V around 100 Hz) is connected to an aqueous supercapacitor fabricated from nanofibrous carbon paper electrodes and a polypyrrole-based (PPy(DBS)) smart membrane separator. A potential below −400mV from the energy harvester applied to the supercapacitor turns the smart membrane separator ‘ON’ and results in a unidirectional ionic current of Li+ ions. As the potential developed by the harvester cycles above ∼50 mV, the membrane separator switches ‘OFF’ and prevents the discharge of the rectified current. This leads to a continuous polarization of ions towards electrical fields relevant for powering electronics. This article is the first description and demonstration of an energy harvesting and storage system that can directly convert the electrical energy from a vibration energy harvester into electrochemical energy without the use of passive circuit components for power rectification.
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Gao, Jing, Bin Chen, and Xiang Wu. "ULTRADEEP DIAMOND GENESIS AT REDOX CONDITIONS OF SLAB-MANTLE BOUNDARY." In 113th Annual GSA Cordilleran Section Meeting - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017cd-292899.
Full textReports on the topic "Redox condition"
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Efurd, D. W., W. Runde, and C. D. Tait. Neptunium redox behavior and solubility in J-13 conditions. Office of Scientific and Technical Information (OSTI), August 1997. http://dx.doi.org/10.2172/522542.
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Bergin, Paul, Reuven Glick, and Jyh-Lin Wu. Mussa Redux and Conditional PPP. Cambridge, MA: National Bureau of Economic Research, August 2012. http://dx.doi.org/10.3386/w18331.
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Banin, Amos, Joseph Stucki, and Joel Kostka. Redox Processes in Soils Irrigated with Reclaimed Sewage Effluents: Field Cycles and Basic Mechanism. United States Department of Agriculture, July 2004. http://dx.doi.org/10.32747/2004.7695870.bard.
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The overall objectives of the project were: (a) To measure and study in situ the effect of irrigation with reclaimed sewage effluents on redox processes and related chemical dynamics in soil profiles of agricultural fields. (b) To study under controlled conditions the kinetics and equilibrium states of selected processes that affect redox conditions in field soils or that are effected by them. Specifically, these include the effects on heavy metals sorption and desorption, and the effect on pesticide degradation. On the basis of the initial results from the field study, increased effort was devoted to clarifying and quantifying the effects of plants and water regime on the soil's redox potential while the study of heavy metals sorption was limited. The use of reclaimed sewage effluents as agricultural irrigation water is increasing at a significant rate. The relatively high levels of suspended and, especially, dissolved organic matter and nitrogen in effluents may affect the redox regime in field soils irrigated with them. In turn, the changes in redox regime may affect, among other parameters, the organic matter and nitrogen dynamics of the root zone and trace organic decomposition processes. Detailed data of the redox potential regime in field plots is lacking, and the detailed mechanisms of its control are obscure and not quantified. The study established the feasibility of long-term, non-disturbing monitoring of redox potential regime in field soils. This may enable to manage soil redox under conditions of continued inputs of wastewater. The importance of controlling the degree of wastewater treatment, particularly of adding ultrafiltration steps and/or tertiary treatment, may be assessed based on these and similar results. Low redox potential was measured in a field site (Site A, KibutzGivat Brenner), that has been irrigated with effluents for 30 years and was used for 15 years for continuous commercial sod production. A permanently reduced horizon (Time weighted averaged pe= 0.33±3.0) was found in this site at the 15 cm depth throughout the measurement period of 10 months. A drastic cultivation intervention, involving prolonged drying and deep plowing operations may be required to reclaim such soils. Site B, characterized by a loamy texture, irrigated with tap water for about 20 years was oxidized (Time weighted average pe=8.1±1.0) throughout the measurement period. Iron in the solid phases of the Givat Brenner soils is chemically-reduced by irrigation. Reduced Fe in these soils causes a change in reactivity toward the pesticide oxamyl, which has been determined to be both cytotoxic and genotoxic to mammalian cells. Reaction of oxamyl with reduced-Fe clay minerals dramatically decreases its cytotoxicity and genotoxicity to mammalian cells. Some other pesticides are affected in the same manner, whereas others are affected in the opposite direction (become more cyto- and genotoxic). Iron-reducing bacteria (FeRB) are abundant in the Givat Brenner soils. FeRB are capable of coupling the oxidation of small molecular weight carbon compounds (fermentation products) to the respiration of iron under anoxic conditions, such as those that occur under flooded soil conditions. FeRB from these soils utilize a variety of Fe forms, including Fe-containing clay minerals, as the sole electron acceptor. Daily cycles of the soil redox potential were discovered and documented in controlled-conditions lysimeter experiments. In the oxic range (pe=12-8) soil redox potential cycling is attributed to the effect of the daily temperature cycle on the equilibrium constant of the oxygenation reaction of H⁺ to form H₂O, and is observed under both effluent and freshwater irrigation. The presence of plants affects considerably the redox potential regime of soils. Redox potential cycling coupled to the irrigation cycles is observed when the soil becomes anoxic and the redox potential is controlled by the Fe(III)/Fe(II) redox couple. This is particularly seen when plants are grown. Re-oxidation of the soil after soil drying at the end of an irrigation cycle is affected to some degree by the water quality. Surprisingly, the results suggest that under certain conditions recovery is less pronounced in the freshwater irrigated soils.
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Fendorf, Scott. Subsurface Conditions Controlling Uranium Incorporation in Iron Oxides: A Redox Stable Sink. Office of Scientific and Technical Information (OSTI), April 2016. http://dx.doi.org/10.2172/1245538.
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Gadd, M. G., J. M. Peter, T A Fraser, and D. Layton-Matthews. Paleoredox and lithogeochemical indicators of the environment of formation and genesis of the Monster River hyper-enriched black shale showing, Yukon. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/328004.
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Northern Yukon hosts occurrences of Middle Devonian hyper-enriched black shale (HEBS) Ni-Mo-Zn-platinum-group element-Au-Re mineralization, including the Monster River showing in the Ogilvie Mountains. This mineralization has been documented predominantly in the Paleozoic Richardson trough; however, the Monster River showing is atypical, occurring within the Blackstone trough, more than 200 km to the west on the southern margin of the Yukon block. The ambient paleoredox conditions of the marine water column and sediments may be primary controlling factors in HEBS formation. We use major and trace element lithogeochemistry to better understand ambient paleoenvironmental redox conditions through the application of robust redox proxies to HEBS mineralization and host rocks. Uniformly negative Ce anomalies (0.6-0.9) indicate that the water column was predominantly suboxic throughout the deposition interval, even during HEBS mineralization. Although there is a strong terrigenous influence on the rare earth element-yttrium (REE-Y) abundances of the sedimentary rocks, superchondritic Y/Ho ratios (&gt;27) indicate that seawater contributed REE-Y to the host rocks and HEBS. High (&gt;10) authigenic Mo/U ratios indicate that a Fe-Mn particulate shuttle operated in the water column; this is corroborated by negative Ce anomalies and high Y/Ho ratios. The data indicate that metalliferous sedimentary rocks formed by hydrogenous metal enrichment (e.g. Ni, Mo, Pt) caused by ferromanganese oxyhydroxide particulate shuttling as chemical sediments; moreover, the REE- and Mo-based paleoenvironmental indicators suggest a complexly redox-stratified depositional environment with an abundant supply of metals, metalloids, and sulfur.
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Scholz, Florian. Sedimentary fluxes of trace metals, radioisotopes and greenhouse gases in the southwestern Baltic Sea Cruise No. AL543, 23.08.2020 – 28.08.2020, Kiel – Kiel - SEDITRACE. GEOMAR Helmholtz Centre for Ocean Research Kiel, November 2020. http://dx.doi.org/10.3289/cr_al543.
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R/V Alkor Cruise AL543 was planned as a six-day cruise with a program of water column and sediment sampling in Kiel Bight and the western Baltic Sea. Due to restrictions related to the Covid-19 pandemic, the original plan had to be changed and the cruise was realized as six oneday cruises with sampling in Kiel Bight exclusively. The first day was dedicated to water column and sediment sampling for radionuclide analyses at Boknis Eck and Mittelgrund in Eckernförde Bay. On the remaining five days, water column, bottom water, sediment and pore water samples were collected at eleven stations covering different types of seafloor environment (grain size, redox conditions) in western Kiel Bight. The data and samples obtained on cruise AL543 will be used to investigate (i) the sedimentary cycling of bio-essential metals (e.g., nickel, zinc, and their isotopes) as a function of variable redox conditions, (ii) the impact of submarine groundwater discharge and diffusive benthic fluxes on the distribution of radium and radon as well as greenhouse gases (methane and nitrous oxide) in the water column, and (iii) to characterize and quantify the impact of coastal erosion on sedimentary iron, phosphorus and rare earth element cycling in Kiel Bight.
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Simandl, G. J., R. J. D'Souza, S. Paradis, and J. Spence. Rare-earth element content of carbonate minerals in sediment-hosted Pb-Zn deposits, southern Canadian Rocky Mountains. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/328001.
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Paleozoic platform carbonate rocks of the Rocky Mountains host Mississippi Valley-type (MVT), magnesite, barite, and REE-barite-fluorite deposits. Farther west, platform carbonate rocks of the Kootenay Arc host MVT and fracture-controlled replacement (FCR) deposits. This is the first systematic LA-ICP-MS study of carbonates in MVT and FCR deposits. We investigated seven MVT deposits in the Rocky Mountains, and five MVT deposits in the Kootenay Arc. None of the post-Archean Australian shale (PAAS)-normalized REE profiles show light REE (LREE) depletion and strong negative Ce anomalies characteristic of modern seawater: some profiles are nearly flat; others show depletion in LREE similar to seawater but without negative Ce anomalies; others are middle REE enriched. Carbonates with a strong positive Eu anomaly precipitated from or interacted with different fluids than carbonates with flatter profiles without a strong positive Eu anomaly. REE signatures reflect crystallization conditions of primary carbonates, and crystallization and re-equilibration conditions of carbonates with ambient fluids during diagenesis, deep burial, and/or metamorphic recrystallization. Chemical evolution of fluids along their migration path, fluid-to-rock ratio, fluid acidity, redox, and temperature also influence REE profile shape, which helps establish genetic and timing constraints on studied deposits and improves knowledge of the metallogeny of the Kootenay Arc and Rocky Mountains.
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Christopher, David A., and Avihai Danon. Plant Adaptation to Light Stress: Genetic Regulatory Mechanisms. United States Department of Agriculture, May 2004. http://dx.doi.org/10.32747/2004.7586534.bard.
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Original Objectives: 1. Purify and biochemically characterize RB60 orthologs in higher plant chloroplasts; 2. Clone the gene(s) encoding plant RB60 orthologs and determine their structure and expression; 3. Manipulate the expression of RB60; 4. Assay the effects of altered RB60 expression on thylakoid biogenesis and photosynthetic function in plants exposed to different light conditions. In addition, we also examined the gene structure and expression of RB60 orthologs in the non-vascular plant, Physcomitrella patens and cloned the poly(A)-binding protein orthologue (43 kDa RB47-like protein). This protein is believed to a partner that interacts with RB60 to bind to the psbA5' UTR. Thus, to obtain a comprehensive view of RB60 function requires analysis of its biochemical partners such as RB43. Background & Achievements: High levels of sunlight reduce photosynthesis in plants by damaging the photo system II reaction center (PSII) subunits, such as D1 (encoded by the chloroplast tpsbAgene). When the rate of D1 synthesis is less than the rate of photo damage, photo inhibition occurs and plant growth is decreased. Plants use light-activated translation and enhanced psbAmRNA stability to maintain D1 synthesis and replace the photo damaged 01. Despite the importance to photosynthetic capacity, these mechanisms are poorly understood in plants. One intriguing model derived from the algal chloroplast system, Chlamydomonas, implicates the role of three proteins (RB60, RB47, RB38) that bind to the psbAmRNA 5' untranslated leader (5' UTR) in the light to activate translation or enhance mRNA stability. RB60 is the key enzyme, protein D1sulfide isomerase (Pill), that regulates the psbA-RN :Binding proteins (RB's) by way of light-mediated redox potentials generated by the photosystems. However, proteins with these functions have not been described from higher plants. We provided compelling evidence for the existence of RB60, RB47 and RB38 orthologs in the vascular plant, Arabidopsis. Using gel mobility shift, Rnase protection and UV-crosslinking assays, we have shown that a dithiol redox mechanism which resembles a Pill (RB60) activity regulates the interaction of 43- and 30-kDa proteins with a thermolabile stem-loop in the 5' UTR of the psbAmRNA from Arabidopsis. We discovered, in Arabidopsis, the PD1 gene family consists of II members that differ in polypeptide length from 361 to 566 amino acids, presence of signal peptides, KDEL motifs, and the number and positions of thioredoxin domains. PD1's catalyze the reversible formation an disomerization of disulfide bonds necessary for the proper folding, assembly, activity, and secretion of numerous enzymes and structural proteins. PD1's have also evolved novel cellular redox functions, as single enzymes and as subunits of protein complexes in organelles. We provide evidence that at least one Pill is localized to the chloroplast. We have used PDI-specific polyclonal and monoclonal antisera to characterize the PD1 (55 kDa) in the chloroplast that is unevenly distributed between the stroma and pellet (containing membranes, DNA, polysomes, starch), being three-fold more abundant in the pellet phase. PD1-55 levels increase with light intensity and it assembles into a high molecular weight complex of ~230 kDa as determined on native blue gels. In vitro translation of all 11 different Pill's followed by microsomal membrane processing reactions were used to differentiate among PD1's localized in the endoplasmic reticulum or other organelles. These results will provide.1e insights into redox regulatory mechanisms involved in adaptation of the photosynthetic apparatus to light stress. Elucidating the genetic mechanisms and factors regulating chloroplast photosynthetic genes is important for developing strategies to improve photosynthetic efficiency, crop productivity and adaptation to high light environments.
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Mueller, C., S. J. Piercey, M. G. Babechuk, and D. Copeland. Stratigraphy and lithogeochemistry of the Goldenville horizon and associated rocks, Baie Verte Peninsula, Newfoundland. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/328990.
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The Goldenville horizon in the Baie Verte Peninsula is an important stratigraphic horizon that hosts primary (Cambrian to Ordovician) exhalative magnetite and pyrite and was a chemical trap for younger (Silurian to Devonian) orogenic gold mineralization. The horizon is overlain by basaltic flows and volcaniclastic rocks, is intercalated with variably coloured argillites and cherts, and underlain by mafic volcaniclastic rocks; the entire stratigraphy is cut by younger fine-grained mafic dykes and coarser gabbro. Lithogeochemical signatures of the Goldenville horizon allow it to be divided into high-Fe iron formation (HIF; &gt;50% Fe2O3), low-Fe iron formation (LIF; 15-50% Fe2O3), and argillite with iron minerals (AIF; &lt;15% Fe2O3). These variably Fe-rich rocks have Fe-Ti-Mn-Al systematics consistent with element derivation from varying mineral contributions from hydrothermal venting and ambient detrital sedimentation. Post-Archean Australian Shale (PAAS)-normalized rare earth element (REE) signatures for the HIF samples have negative Ce anomalies and patterns similar to modern hydrothermal sediment deposited under oxygenated ocean conditions. The PAAS-normalized REE signatures of LIF samples have positive Ce anomalies, similar to hydrothermal sediment deposited under anoxic to sub-oxic conditions. The paradoxical Ce behaviour is potentially explained by the Mn geochemistry of the LIF samples. The LIF have elevated MnO contents (2.0-7.5 weight %), suggesting that Mn from hydrothermal fluids was oxidized in an oxygenated water column during hydrothermal venting, Mn-oxides then scavenged Ce from seawater, and these Mn-oxides were subsequently deposited in the hydrothermal sediment. The Mn-rich LIF samples with positive Ce anomalies are intercalated with HIF with negative Ce anomalies, both regionally and on a metre scale within drill holes. Thus, the LIF positive Ce anomaly signature may record extended and particle-specific scavenging rather than sub-oxic/redox-stratified marine conditions. Collectively, results suggest that the Cambro-Ordovician Taconic seaway along the Laurentian margin may have been completely or near-completely oxygenated at the time of Goldenville horizon deposition.
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Lahav, Ori, Albert Heber, and David Broday. Elimination of emissions of ammonia and hydrogen sulfide from confined animal and feeding operations (CAFO) using an adsorption/liquid-redox process with biological regeneration. United States Department of Agriculture, March 2008. http://dx.doi.org/10.32747/2008.7695589.bard.
Full textAbstract:
The project was originally aimed at investigating and developing new efficient methods for cost effective removal of ammonia (NH₃) and hydrogen sulfide (H₂S) from Concentrated Animal Feeding Operations (CAFO), in particular broiler and laying houses (NH₃) and hog houses (H₂S). In both cases, the principal idea was to design and operate a dedicated air collection system that would be used for the treatment of the gases, and that would work independently from the general ventilation system. The advantages envisaged: (1) if collected at a point close to the source of generation, pollutants would arrive at the treatment system at higher concentrations; (2) the air in the vicinity of the animals would be cleaner, a fact that would promote animal growth rates; and (3) collection efficiency would be improved and adverse environmental impact reduced. For practical reasons, the project was divided in two: one effort concentrated on NH₃₍g₎ removal from chicken houses and another on H₂S₍g₎ removal from hog houses. NH₃₍g₎ removal: a novel approach was developed to reduce ammonia emissions from CAFOs in general, and poultry houses in particular. Air sucked by the dedicated air capturing system from close to the litter was shown to have NH₃₍g₎ concentrations an order of magnitude higher than at the vents of the ventilation system. The NH₃₍g₎ rich waste air was conveyed to an acidic (0<pH<~5) bubble column reactor where NH₃ was converted to NH₄⁺. The reactor operated in batch mode, starting at pH 0 and was switched to a new acidic absorption solution just before NH₃₍g₎ breakthrough occurred, at pH ~5. Experiments with a wide range of NH₃₍g₎ concentrations showed that the absorption efficiency was practically 100% throughout the process as long as the face velocity was below 4 cm/s. The potential advantages of the method include high absorption efficiency, lower NH₃₍g₎ concentrations in the vicinity of the birds, generation of a valuable product and the separation between the ventilation and ammonia treatment systems. A small scale pilot operation conducted for 5 weeks in a broiler house showed the approach to be technically feasible. H₂S₍g₎ removal: The main goal of this part was to develop a specific treatment process for minimizing H₂S₍g₎ emissions from hog houses. The proposed process consists of three units: In the 1ˢᵗ H₂S₍g₎ is absorbed into an acidic (pH<2) ferric iron solution and oxidized by Fe(III) to S⁰ in a bubble column reactor. In parallel, Fe(III) is reduced to Fe(II). In the 2ⁿᵈ unit Fe(II) is bio-oxidized back to Fe(III) by Acidithiobacillus ferrooxidans (AF).In the 3ʳᵈ unit S⁰ is separated from solution in a gravity settler. The work focused on three sub-processes: the kinetics of H₂S absorption into a ferric solution at low pH, the kinetics of Fe²⁺ oxidation by AF and the factors that affect ferric iron precipitation (a main obstacle for a continuous operation of the process) under the operational conditions. H₂S removal efficiency was found higher at a higher Fe(III) concentration and also higher for higher H₂S₍g₎ concentrations and lower flow rates of the treated air. The rate limiting step of the H₂S reactive absorption was found to be the chemical reaction rather than the transition from gas to liquid phase. H₂S₍g₎ removal efficiency of >95% was recorded with Fe(III) concentration of 9 g/L using typical AFO air compositions. The 2ⁿᵈ part of the work focused on kinetics of Fe(II) oxidation by AF. A new lab technique was developed for determining the kinetic equation and kinetic parameters (KS, Kₚ and mₘₐₓ) for the bacteria. The 3ʳᵈ part focused on iron oxide precipitation under the operational conditions. It was found that at lower pH (1.5) jarosite accumulation is slower and that the performance of the AF at this pH was sufficient for successive operation of the proposed process at the H₂S fluxes predicted from AFOs. A laboratory-scale test was carried out at Purdue University on the use of the integrated system for simultaneous hydrogen sulfide removal from a H₂S bubble column filled with ferric sulfate solution and biological regeneration of ferric ions in a packed column immobilized with enriched AFbacteria. Results demonstrated the technical feasibility of the integrated system for H₂S removal and simultaneous biological regeneration of Fe(III) for potential continuous treatment of H₂S released from CAFO. NH₃ and H₂S gradient measurements at egg layer and swine barns were conducted in winter and summer at Purdue. Results showed high potential to concentrate NH₃ and H₂S in hog buildings, and NH₃ in layer houses. H₂S emissions from layer houses were too low for a significant gradient. An NH₃ capturing system was designed and tested in a 100-chicken broiler room. Five bell-type collecting devices were installed over the litter to collect NH₃ emissions. While the air extraction system moved only 10% of the total room ventilation airflow rate, the fraction of total ammonia removed was 18%, because of the higher concentration air taken from near the litter. The system demonstrated the potential to reduce emissions from broiler facilities and to concentrate the NH₃ effluent for use in an emission control system. In summary, the project laid a solid foundation for the implementation of both processes, and also resulted in a significant scientific contribution related to AF kinetic studies and ferrous analytical measurements.