Academic literature on the topic 'Redox des particules'
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Journal articles on the topic "Redox des particules":
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Peña, Fernando J., Cristian O’Flaherty, José M. Ortiz Rodríguez, Francisco E. Martín Cano, Gemma L. Gaitskell-Phillips, María C. Gil, and Cristina Ortega Ferrusola. "Redox Regulation and Oxidative Stress: The Particular Case of the Stallion Spermatozoa." Antioxidants 8, no. 11 (November 19, 2019): 567. http://dx.doi.org/10.3390/antiox8110567.
Abstract:
Redox regulation and oxidative stress have become areas of major interest in spermatology. Alteration of redox homeostasis is recognized as a significant cause of male factor infertility and is behind the damage that spermatozoa experience after freezing and thawing or conservation in a liquid state. While for a long time, oxidative stress was just considered an overproduction of reactive oxygen species, nowadays it is considered as a consequence of redox deregulation. Many essential aspects of spermatozoa functionality are redox regulated, with reversible oxidation of thiols in cysteine residues of key proteins acting as an “on–off” switch controlling sperm function. However, if deregulation occurs, these residues may experience irreversible oxidation and oxidative stress, leading to malfunction and ultimately death of the spermatozoa. Stallion spermatozoa are “professional producers” of reactive oxygen species due to their intense mitochondrial activity, and thus sophisticated systems to control redox homeostasis are also characteristic of the spermatozoa in the horse. As a result, and combined with the fact that embryos can easily be collected in this species, horses are a good model for the study of redox biology in the spermatozoa and its impact on the embryo.
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Reyhani, Amin, Thomas G. McKenzie, Qiang Fu, and Greg G. Qiao. "Redox-Initiated Reversible Addition–Fragmentation Chain Transfer (RAFT) Polymerization." Australian Journal of Chemistry 72, no. 7 (2019): 479. http://dx.doi.org/10.1071/ch19109.
Abstract:
Reversible addition–fragmentation chain transfer (RAFT) polymerization initiated by a radical-forming redox reaction between a reducing and an oxidizing agent (i.e. ‘redox RAFT’) represents a simple, versatile, and highly useful platform for controlled polymer synthesis. Herein, the potency of a wide range of redox initiation systems including enzyme-mediated redox reactions, the Fenton reaction, peroxide-based reactions, and metal-catalyzed redox reactions, and their application in initiating RAFT polymerization, are reviewed. These redox-RAFT polymerization methods have been widely studied for synthesizing a broad range of homo- and co-polymers with tailored molecular weights, compositions, and (macro)molecular structures. It has been demonstrated that redox-RAFT polymerization holds particular promise due to its excellent performance under mild conditions, typically operating at room temperature. Redox-RAFT polymerization is therefore an important and core part of the RAFT methodology handbook and may be of particular importance going forward for the fabrication of polymeric biomaterials under biologically relevant conditions or in biological systems, in which naturally occurring redox reactions are prevalent.
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Godoi, Marco Antônio Abrantes de Barros. "MITOLOGIA DO MUNDO VEGETAL GRECO-ROMANO: ALGUNS EXEMPLOS PARTICULARES." PRINCIPIA, no. 40 (December 8, 2020): 119–25. http://dx.doi.org/10.12957/principia.2020.55873.
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Desde os tempos primitivos, o animismo vem sendo uma característica universal da visão que o ser humano tem sobre a sua experiência com seu ambiente, sendo uma perspectiva holística do universo, este ser humano encara-o como um universo vivo, seja uma pedra, seja um rio, ou a vegetação ao redor, todos possuem um espírito que se manifesta e se conecta com todos ao redor. A partir desta visão de mundo primevo, as sociedades posteriores construíram uma visão do mundo vegetal complexa que leva a representações de cada elemento da natureza. Aqui pretendemos observar, na primeira parte um aspecto geral desta perspectiva sobre uma visão do mito e da forma como o homem veio construindo esta percepção do mundo vegetal e seu elo com sua vida. Na segunda parte estudaremos algumas particularidades do mito do carvalho, do narciso, da oliveira e da videira.
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Albrecht, Simone C., Mirko C. Sobotta, Daniela Bausewein, Isabel Aller, Rüdiger Hell, Tobias P. Dick, and Andreas J. Meyer. "Redesign of Genetically Encoded Biosensors for Monitoring Mitochondrial Redox Status in a Broad Range of Model Eukaryotes." Journal of Biomolecular Screening 19, no. 3 (August 16, 2013): 379–86. http://dx.doi.org/10.1177/1087057113499634.
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The development of genetically encoded redox biosensors has paved the way toward chemically specific, quantitative, dynamic, and compartment-specific redox measurements in cells and organisms. In particular, redox-sensitive green fluorescent proteins (roGFPs) have attracted major interest as tools to monitor biological redox changes in real time and in vivo. Most recently, the engineering of a redox relay that combines glutaredoxin (Grx) with roGFP2 as a translational fusion (Grx1-roGFP2) led to a biosensor for the glutathione redox potential ( EGSH). The expression of this probe in mitochondria is of particular interest as mitochondria are the major source of oxidants, and their redox status is closely connected to cell fate decisions. While Grx1-roGFP2 can be expressed in mammalian mitochondria, it fails to enter mitochondria in various nonmammalian model organisms. Here we report that inversion of domain order from Grx1-roGFP2 to roGFP2-Grx1 yields a biosensor with perfect mitochondrial targeting while fully maintaining its biosensor capabilities. The redesigned probe thus allows extending in vivo observations of mitochondrial redox homeostasis to important nonmammalian model organisms, particularly plants and insects.
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Paffen, Alina, Christopher Cremer, and Frederic W. Patureau. "Phenotellurazine redox catalysts: elements of design for radical cross-dehydrogenative coupling reactions." Beilstein Journal of Organic Chemistry 20 (June 4, 2024): 1292–97. http://dx.doi.org/10.3762/bjoc.20.112.
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Redox active phenotellurazine catalysts have been recently utilized in two different cross-dehydrogenative coupling reactions. In this study, we revisit the design of the phenotellurazine redox catalysts. In particular, we investigate the level of cooperativity between the Te- and N-centers, the effect of secondary versus tertiary N-centers, the effect of heterocyclic versus non-heterocyclic structures, and the effect of substitution patterns on the redox catalytic activity.
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Evtugyn, Gennady A., Anna V. Porfireva, and Ivan I. Stoikov. "Electrochemical DNA sensors based on spatially distributed redox mediators: challenges and promises." Pure and Applied Chemistry 89, no. 10 (September 26, 2017): 1471–90. http://dx.doi.org/10.1515/pac-2016-1124.
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AbstractDNA and aptasensors are widely used for fast and reliable detection of disease biomarkers, pharmaceuticals, toxins, metabolites and other species necessary for biomedical diagnostics. In the overview, the concept of spatially distributed redox mediators is considered with particular emphasis to the signal generation and biospecific layer assembling. The application of non-conductive polymers bearing redox labels, supramolecular carriers with attached DNA aptamers and redox active dyes and E-sensor concept are considered as examples of the approach announced.
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Barbosa, Milena Cristian do Nascimento, Márcia Taynara Machado Almeida, Mayrhon José Abrantes Farias, and Adriano Lopes de Souza. "DESAFIOS E POSSIBILIDADES DO ESTÁGIO SUPERVISIONADO EM EDUCAÇÃO FÍSICA: A EXPERIÊNCIA COM O ENSINO HÍBRIDO." Revista Docência e Cibercultura 6, no. 5 (October 6, 2022): 252–66. http://dx.doi.org/10.12957/redoc.2022.66371.
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O presente artigo objetiva relatar as experiências vividas por acadêmicas do curso de Licenciatura em Educação Física durante o do Estágio Supervisionado em uma escola pública no município de Tocantinópolis-TO. Nesse trabalho utilizamos a narrativa autobiográfica para abordar os desafios e as possibilidades vivenciadas no modelo de Ensino Híbrido, problematizando a didática utilizada nos portfólios e propondo reflexões quanto ao papel da Educação Física em meio a um contexto de ensino fragilizado, incluindo os respectivos impactos nas práticas corporais/atividades realizadas na escola. A partir dessa experiência, foi possível perceber a importância do uso de outras linguagens, para além da escrita, na apropriação dos conhecimentos que cerceiam o cotidiano escolar, de forma geral, e os momentos das aulas de Educação Física, de forma particular.
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Jacob, Claus. "Redox signalling via the cellular thiolstat." Biochemical Society Transactions 39, no. 5 (September 21, 2011): 1247–53. http://dx.doi.org/10.1042/bst0391247.
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Research conducted during the last two decades has provided evidence for the existence of an extensive intracellular redox signalling, control and feedback network based on different cysteine-containing proteins and enzymes. Together, these proteins enable the living cell to sense and respond towards external and internal redox changes in a measured, gradual, appropriate and mostly reversible manner. The (bio)chemical basis of this regulatory ‘thiolstat’ is provided by the complex redox chemistry of the amino acid cysteine, which occurs in vivo in various sulfur chemotypes and is able to participate in different redox processes. Although our knowledge of the biological redox behaviour of sulfur (i.e. cysteine or methionine) is expanding, numerous questions still remain. Future research will need to focus on the individual proteins involved in this redox system, their particular properties and specific roles in cellular defence and survival. Once it is more fully understood, the cellular thiolstat and its individual components are likely to form prominent targets for drug design.
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Yang, Kylie, Jacek L. Kolanowski, and Elizabeth J. New. "Mitochondrially targeted fluorescent redox sensors." Interface Focus 7, no. 2 (April 6, 2017): 20160105. http://dx.doi.org/10.1098/rsfs.2016.0105.
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The balance of oxidants and antioxidants within the cell is crucial for maintaining health, and regulating physiological processes such as signalling. Consequently, imbalances between oxidants and antioxidants are now understood to lead to oxidative stress, a physiological feature that underlies many diseases. These processes have spurred the field of chemical biology to develop a plethora of sensors, both small-molecule and fluorescent protein-based, for the detection of specific oxidizing species and general redox balances within cells. The mitochondrion, in particular, is the site of many vital redox reactions. There is therefore a need to target redox sensors to this particular organelle. It has been well established that targeting mitochondria can be achieved by the use of a lipophilic cation-targeting group, or by utilizing natural peptidic mitochondrial localization sequences. Here, we review how these two approaches have been used by a number of researchers to develop mitochondrially localized fluorescent redox sensors that are already proving useful in providing insights into the roles of reactive oxygen species in the mitochondria.
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Cicconi, Maria Rita, Charles Le Losq, Roberto Moretti, and Daniel R. Neuville. "Magmas are the Largest Repositories and Carriers of Earth’s Redox Processes." Elements 16, no. 3 (June 1, 2020): 173–78. http://dx.doi.org/10.2138/gselements.16.3.173.
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Magma is the most important chemical transport agent throughout our planet. This paper provides an overview of the interplay between magma redox, major element chemistry, and crystal and volatile content, and of the influence of redox on the factors that drive igneous system dynamics. Given the almost infinite combinations of temperature, pressure, and chemical compositions relevant to igneous petrology, we focus on the concepts and methods that redox geochemistry provides to understand magma formation, ascent, evolution and crystallization. Particular attention is paid to the strong and complex interplay between melt structure and chemistry, and to the influence that redox conditions have on melt properties, crystallization mechanisms and the solubility of volatile components.
Dissertations / Theses on the topic "Redox des particules":
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Guida, Manrique Leydy Carolina. "Mécanismes contrôlant la séquestration du gadolinium, du rhénium et du sélénium dans des conditions de faible teneur en oxygène." Electronic Thesis or Diss., Université Grenoble Alpes, 2024. http://www.theses.fr/2024GRALU015.
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Les éléments traces, malgré leur rareté (moins de 100 parties par million) sur Terre, remplissent diverses fonctions : certains agissent comme des micronutriments, tandis que d'autres, appelés métaux critiques, possèdent des applications industrielles et médicales uniques. Dans les systèmes aquatiques naturels dépourvus d'oxygène, les transferts d'électrons impliquent des réactions biogéochimiques catalysées par le fer, le soufre et les éléments traces. Comprendre leur réactivité dans ces environnements reste un défi. Ma recherche de doctorat se concentre sur combler cette lacune de connaissance concernant trois éléments spécifiques (rhénium (Re), sélénium (Se) et gadolinium (Gd)). Ils existent sous diverses formes chimiques aqueuses dans l'eau : anion monovalent (perrhénate, ReO4—), anion divalent (sélénate, SeO42— et sélénite, SeO32—) ou cation (gadolinium, Gd3+). Le rhénium est un métal critique, tandis que le sélénium est un élément bioessentiel à faibles niveaux et devient toxique à des concentrations plus élevées. Le gadolinium est un élément des terres rares et un métal critique également, en raison de son utilisation étendue comme agent de contraste dans l'imagerie par résonance magnétique (IRM).Ces éléments sont les plus concentrés dans les sédiments marins formés dans des environnements dépourvus d'oxygène. Les phases minérales courantes comprennent la pyrite (FeS2) et la magnétite (Fe3O4), selon la teneur en sulfure dans ces environnements et l'origine (autogène vs détritique, par exemple, à partir de roches volcaniques) des particules. Ma recherche, présentée sur quatre chapitres, étudie les processus de réduction de surface (Re(VII), Se(VI) et Se(IV)) et la sorption (Gd(III)) sur/dans les particules de magnétite et de pyrite. En utilisant diverses méthodes analytiques telles que la spectroscopie XAFS, la spectroscopie STEM-EELS et le MC-ICP-MS, notre étude révèle des voies réactives distinctes. Re(VII) réagit avec l'eau sulfurée pour former des nanoparticules de Re(III, IV, V)2S7, tandis qu'à des concentrations plus faibles, le Re est réduit et incorporé dans les particules, selon des voies caractérisées par une fraction isotopique moindre avec la pyrite qu'avec la magnétite. Nous montrons également que les nanoparticules de pyrite réduisent le Se(VI) et le Se(IV), jusqu'à obtenir du Se(0) en surface ou du Se(-I) en structure, selon que l'adsorption ou la co-précipitation se produit. Enfin, le Gd se substitue au Fe(III) dans les nanoparticules de magnétite jusqu'à une substitution de 5% de Fe par Gd. Nous tentons d'unifier le comportement d'affinité de ces éléments traces et d'autres avec les sédiments riches en Fe anoxiques à la lumière du principe des acides et des bases durs et mous.L'étude apporte de nouvelles perspectives sur les mécanismes qui régissent la séquestration des métaux et métalloïdes dans les environnements sédimentaires. La signification de cette recherche réside dans sa pertinence pour les entreprises scientifiques et technologiques contemporaines, en particulier pour comprendre comment les processus dans les systèmes riches en Fe et en sulfures fonctionnent, tels que les éléments traces, la mobilité du Fe et du S, l'équilibre des masses dans les cycles sédimentaires mondiaux, jusqu'à l'exploration, l'exploitation minière et le recyclage des gisements potentiels de métaux. De plus, elle améliore notre compréhension actuelle de l'utilisation des proxies paléoenvironnementaux pour reconstruire la formation de la Terre. Enfin, cette étude a également des implications pour le traitement des déchets nucléaires et de la pollution, en particulier dans la gestion de la contamination par le sélénium (Se) et le gadolinium (Gd)Trace elements, despite their scarcity (less than 100 parts per million) on Earth, serve diverse purposes: some act as micronutrients, while others, known as critical metals, possess unique industrial and medical applications. In oxygen-deprived natural aquatic systems electron transfers involve biogeochemical reactions catalyzed by iron, sulfur and trace elements. Understanding their reactivity in these environments remains a challenge. My Ph.D. research focus on filling this knowledge gap concerning three specific elements (rhenium (Re), selenium (Se), and gadolinium (Gd)). They exist in various chemical aqueous species in water: monovalent anion (perrhenate, ReO4—), divalent anion (selenate, SeO42—and selenite, SeO32—) or cation (Gadolinium, Gd3+). Rhenium is a critical metal, while selenium is a bioessential element at low levels, and becomes toxic in higher concentrations. Gadolinium is a rare earth element and a critical metal as well, due to its wide use as a contrast agent in magnetic resonance imaging (MRI).These elements are most concentrated in marine sediments formed in oxygen-deprived environments. Common mineral phases include pyrite (FeS2) and magnetite (Fe3O4) depending on sulfide content in those environments, and origin (autogenic vs. detritic, e.g., from volcanic rocks) of the particles. My research, presented across four chapters, investigates surface reduction (Re(VII), Se(VI) and Se(IV)) and the sorption (Gd(III)) processes on/into magnetite and pyrite particles. Employing various analytical methods such as XAFS spectroscopy, STEM-EELS spectro microscopie and MC-ICP-MS, our study reveals distinct reactive pathways. Re(VII) reacts with sulfidic water to form Re(III, IV, V)2S7 nanoparticles, while at lower concentrations Re is reduced and incorporated into particles, in different pathways characterized by less isotopic fractionation with pyrite than with magnetite. We also show that pyrite nanoparticles reduce Se(VI) and Se(IV), down to surface Se(0) or structure Se(-I) depending on whether adsorption or co-precipitation occurs. Lastly, Gd substitutes for Fe(III) in magnetite nanoparticles up to 5% Fe substitution by Gd. We attempt to unify the affinity behaviour of these and other trace elements with anoxic Fe-bearing sediments in the light of the hard and soft acids and bases principle.The study provides new insights into the mechanisms that govern the sequestration of metals and metalloids in sedimentary settings. The significance of this research lies in its relevance to contemporary scientific and technological endeavours, particularly in understanding how processes in Fe and sulfidic systems work like trace elements, Fe and S mobility, mass balance in the global sedimentary cycles to the exploration, mining and recycling of potential repositories of metals. Furthermore, it enhances our current understanding of the use of palaeoenvironmental proxies to reconstruct the Earth's formation. Finally, this study also has implications for the treatment of nuclear waste and pollution, particularly in the management of selenium (Se) and gadolinium (Gd) contamination
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CRUZ, FILHO Jaime Luis Cardoso da. "Potenciais pseudo-newtonianos e a radiação escalar emitida por uma fonte girando ao redor de um objeto estelar." Universidade Federal do Pará, 2010. http://repositorio.ufpa.br/jspui/handle/2011/5084.
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Neste trabalho usamos os potenciais pseudo-newtonianos propostos por Paczynski e Wiita, Nowak e Wagoner e Artemova et al. para calcular a radiação escalar emitida por uma fonte em movimento circular e uniforme ao redor de um objeto estelar. Comparamos os resultados obtidos nessa abordagem com os resultados encontrados via teoria quântica de campos no espaço-tempo de Schwarzschild. Obtemos que, do infinito até a órbita circular marginalmente estável (R = 6M) o potencial que melhor reproduz os resultados de Schwarzschild é o de Nowak e Wagoner. Já entre esta órbita e a última órbita circular instável (R = 3M) nenhum dos potenciais pseudo-newtonianos produz resultados satisfatórios, e o potencial newtoniano mostra-se como a melhor aproximação. O potencial de Paczynski e Wiita, o mais utilizado na literatura para analisar discos de acre ção, gerou os resultados menos satisfatórios em nossa análise.
We use the pseudo-newtonian potentials proposed by Paczynski and Wiita, Nowak and Wagoner and Artemova et al. to calculate the scalar radiation emitted by a source in uniform circular motion around a stellar object. We compare the results obtained in this approach with the results obtained via quantum eld theory in Schwarzschild spacetime. We find that, up to the marginally stable circular orbit (R = 6M) the potential that better reproduces the Schwarzschild result is the Nowak and Wagoner one. Between this orbit and the last unstable circular orbit (R = 3M) neither one of the pseudo-newtonian potentials produce satisfactory results, and the newtonian potential turns out to be the best approximation. The Paczy nski and Wiita potential, the most used in the literature to analyze accretion disks, generates the less satisfactory results for this situation.
Books on the topic "Redox des particules":
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Deegan, Patrick. Porphyria. Edited by Patrick Davey and David Sprigings. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780199568741.003.0179.
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This chapter discusses six diseases caused by inborn errors of metabolism affecting the biosynthesis of haem. Haem is a tetracyclic metal-binding compound involved in oxygen transport (in haemoglobin and myoglobin) and redox reactions (e.g. in the cytochrome P450 system). Each of these conditions is caused by a single gene defect in one of the enzymes involved in the biosynthesis of haem. Inheritance is usually autosomal dominant with incomplete penetrance. The enzyme defect results in disease, not as a result of deficiency of the reaction product, but as a result of accumulation of precursors. Early, soluble precursors, 5-aminolaevulinic acid, and porphobilinogen (not porphyrins as such) are neurotoxic and, when present in great excess, as occurs when flux through the haem synthetic pathway is increased in response to particular medications or hormones, lead to acute neurovisceral crises. Later cyclical precursors (porphyrins) in the pathway are also water soluble and excreted in urine, but are susceptible to activation by electromagnetic radiation in the visible spectrum and are converted to free-radical metabolites that cause pain, inflammation, and tissue damage in the skin. The final haem precursors (also porphyrins) are hydrophobic and excreted in the bile and faeces and are also activated by light to toxic metabolites.
Book chapters on the topic "Redox des particules":
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Zahari, Finn, Martin Ziegler, Pouya Doerwald, Christian Wenger, and Hermann Kohlstedt. "Neuromorphic Circuits with Redox-Based Memristive Devices." In Springer Series on Bio- and Neurosystems, 43–85. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-36705-2_2.
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AbstractThis chapter addresses opportunities for memristive devices in the framework of neuromorphic computing. Memristive devices are two-terminal circuit elements, comprising resistance and memory functionality. This simple and likewise ingeniously concept allows beneficial applications in numerous neuromorphic circuits. However, the electrical characteristics as well as the materials and technological framework of memristive devices need an optimization for each specific application. The chapter starts with a short overview of basic principles of biological data processing followed by a taxonomy of different bio-inspired computing architectures, divided into time-dependent and time-independent concepts. Furthermore, the requirements on particular memristive device properties, such as $$I\text {-}V$$ I - V linearity, switching time, retention, number of states, time-dependency, and device variability, are discussed. The results of tangible examples of digital and analog memristive switching devices used in a deep neural network based on CMOS-integrated resistive random access memory devices (RRAMs) for chronic obstructive pulmonary disease (COPD) detection, in stochastic learning, in bio-inspired analog learning, and, finally, in oscillatory computing are presented and discussed.
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Zahari, Finn, Seongae Park, Mamathamba K. Mahadevaiah, Christian Wenger, Hermann Kohlstedt, and Martin Ziegler. "Redox-Based Bi-Layer Metal Oxide Memristive Devices." In Springer Series on Bio- and Neurosystems, 87–114. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-36705-2_3.
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AbstractIn a memristor or a so-called memristive device, the resistance state depends on the previous charge flow through the device. The new resistance state is stored and classifies a memristor as a non-volatile memory device. This likewise unique and simple feature qualifies memristive devices as attractive compartments with regard to the development of a universal memory and beyond von Neumann computing architectures, including in-memory computing and neuromorphic circuits. In this chapter, we present studies on two kinds of bi-layer metal oxide memristive devices with the layer sequences Nb/NbO$$_{\textrm{z}}$$ z /Al$$_2$$ 2 O$$_3$$ 3 /Nb$$_{\textrm{x}}$$ x O$$_{\textrm{y}}$$ y /Au and TiN/TiO$$_\textrm{x}$$ x /HfO$$_\textrm{x}$$ x /Au, either prepared by reactive DC-magnetron sputtering, etching and optical lithography. It is shown that the memristive properties of such devices can be engineered, which enables tailoring of the memristive devices for particular applications.
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Robertson, Jeremy. "Redox deprotection." In Protecting Group Chemistry. Oxford University Press, 2000. http://dx.doi.org/10.1093/hesc/9780198502753.003.0005.
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This chapter focuses on redox deprotection. Oxidation-labile protecting groups offer a means of releasing functional groups under essentially neutral conditions which is useful when hydrolytic deprotection is not tolerated and silyl protecting groups are unsuitable. In particular, a CH2 group that links a functional group to an electron-rich aromatic ring is prone to oxidation giving a hemiacetal, which is unstable with respect to aldehyde formation, and release of the functional group. Some oxidising agents activate the CH2 towards nucleophilic attack by water in a process equivalent overall to abstraction of hydride ion. The chapter then looks at internal redox processes, including free-radical deprotection, protecting group interchange, and photochemical deprotection. It also considers reductive methods, including hydrogenolysis.
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N. Pronkin, Sergey, Nina Yu. Shokina, and Cuong Pham-Huu. "Redox Transitions in Pseudocapacitor Materials: Criteria and Ruling Factors." In Redox Chemistry - From Molecules to Energy Storage [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.104084.
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Pseudocapacitance is a phenomenon of charge storage involving redox transitions at the electrode/electrolyte interface. As the result of an electrode potential modulation, one or few components of the electrode and/or electrolyte change its/their oxidation states. The redox reaction may be confined to the interface or propagate into the bulk of the electrode material, thus significantly increasing the charge (and energy) capacitance of the material. The rate and the reversibility of the interfacial redox reaction are the key factors determining the efficiency of charge storage due to pseudocapacitance phenomena. The influence of the characteristics of the interfacial redox reaction on the efficiency of charge storage in pseudocapacitive materials is considered in the current chapter. In particular, the similarities and the differences between the charge storage in batteries and pseudocapacitors are discussed. The analysis of the pseudocapacitive behavior of electrode material using the impedance spectroscopy is presented.
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Haga, Masa-aki. "Surface-Confined Ruthenium Complexes Bearing Benzimidazole Derivatives: Toward Functional Devices." In Ruthenium - an Element Loved by Researchers [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97071.
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Substitutionally inert ruthenium complexes bearing benzimidazole derivatives have unique electrochemical and photochemical properties. In particular, proton coupled electron transfer (PCET) in ruthenium–benzimidazole complexes leads to rich redox chemistry, which allows e.g. the tuning of redox potentials or switching by deprotonation. Using the background knowledge from acquired from their solution-state chemistry, Ru complexes immobilized on electrode surfaces have been developed and these offer new research directions toward functional molecular devices. The integration of surface-immobilized redox-active Ru complexes with multilayer assemblies via the layer-by-layer (LbL) metal coordination method on ITO electrodes provides new types of functionality. To control the molecular orientation of the complexes on the ITO surface, free-standing tetrapodal phosphonic acid anchor groups were incorporated into tridentate 2,6-bis(benzimidazole-2-yl)pyridine or benzene ligands. The use of the LbL layer growth method also enables “coordination programming” to fabricate multilayered films, as a variety of Ru complexes with different redox potentials and pKa values are available for incorporation into homo- and heterolayer films. Based on this strategy, many functional devices, such as scalable redox capacitors for energy storage, photo-responsive memory devices, proton rocking-chair-type redox capacitors, and protonic memristor devices have been successfully fabricated. Further applications of anchored Ru complexes in photoredox catalysis and dye-sensitized solar cells may be possible. Therefore, surface-confined Ru complexes exhibit great potential to contribute to the development of advanced functional molecular devices.
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Housecroft, Catherine E. "Aqueous solution species." In The Heavier d-Block Metals. Oxford University Press, 1999. http://dx.doi.org/10.1093/hesc/9780198501039.003.0003.
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This chapter focuses on two particular aspects of the chemistry of the second and third row d-block metals in aqueous solution: species present in solution and redox behaviour. It explores the increase in electron withdrawing power of the metal centre which is associated with an increase in oxidation state and is reflected in the fact that the hexaaqua ion of vanadium does not exist in a solution. It also discusses the loss of protons through the polarization of O-H bonds in coordinated water. This leads to the formation of hydroxo ligands and the concomitant generation of dinuclear species. The chapter describes the dramatic effect that the change in ligand has on the relative case of iron(III) reduction. It mentions the use of potential diagrams as a valuable method of displaying the redox behaviour of different species containing a particular element.
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Matata, Bashir M., and Maqsood M. Elahi. "Redox Signaling, Oxidative Stress in Cardiovascular Disease –basic Science and Clinical Aspects." In Blood Oxidant Ties: The Evolving Concepts in Myocardial Injury and Cardiovascular Disease, 1–24. BENTHAM SCIENCE PUBLISHERS, 2023. http://dx.doi.org/10.2174/9789815165012123010004.
Abstract:
The generation of certain species of biomolecules described as reactive oxidant species (ROS e.g., superoxide, O2 -; hydrogen peroxide, H2O2; hydroxyl radicals (OH.)) and reactive nitrogen species (RNS e.g., peroxynitrite, OONO-; nitric oxide, •NO) is a critical step in health and disease . These species play critical roles in cell defences in both animals, and plants. They also perform an important function in the regulation of key cellular signalling pathways such as cell differentiation, proliferation, migration, and apoptosis (commonly described as redox signalling pathways). The imbalance between the levels of ROS and RNS generated to that of antioxidant species may lead to oxidative stress and biomolecular damage, especially in situations where the latter are depleted. Redox biology and oxidative stress are particularly important in ischaemia-reperfusion associated diseases in particular the pathogenesis of cardiovascular disease (CVD). CVD is a major cause of mortality on a global scale, although the exact mechanisms underlying the pathological process are not fully understood. It is believed that ROS play a pivotal role in the progression of CVD. In particular, recent evidence suggests that the development of atherosclerosis is modulated by ROS and influenced by other factors such as inflammatory responses, disturbed blood flow, and arterial wall remodelling. This chapter provides an overview of the pathways of oxidative stress and redox-regulated signalling underlying the genesis and progression of cardiovascular disease.
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Cazacu, Lilia. "Structural properties and interaction mechanisms of some macromolecules with antioxidant activity studied by the small angle scattering method." In Redox Processes with Electron and Proton Transfer, 199–210. Moldova State University, 2023. http://dx.doi.org/10.59295/prtep2023_10.
Abstract:
Studying the structural properties and associative interactions of bioactive components such as protein molecules is of particular interest for expanding the spectrum of industrial applications or optimizing existing ones. Thus, the purpose of this research is to study the structure of some proteins with antioxidant activity such as lactoferrin, glucooxidase, β-lactoglobulin, using the X-ray/neutron small angle scattering method.
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Shorter, Edward. "Nerves Redux." In How Everyone Became Depressed. Oxford University Press, 2013. http://dx.doi.org/10.1093/oso/9780199948086.003.0015.
Abstract:
We might have thought that the concept of nerves ended in 1957 when the United States Post Office Department initiated a fraud proceeding against John Winters of New York City, who had been promoting a product called Orbacine containing bromide and niacin for “every-day nervousness and its symptoms.” Although Winters’ claims went a bit beyond nerves, the Post Office wanted an end to the whole business and Orbacine disappeared. But the concept of nerves had enemies other than the Post Office. Three in particular had tried to do away with it: psychoanalysis, psychopharmacology, and the DSM series. All failed to kill it completely, and the concept lingers on because of its obvious face value: Our patients clearly have a nervous illness or something resembling it. They do not have a “mood disorder.” In medicine the nervous syndrome, the condition that dare not speak its name, has taken on various allures. Once upon a time, hysteria was the equivalent of a nervous diagnosis in women. There were physicians who had little patience with calling their former hysteric patients “depressed”: They remained hysteric! Jacques Frei, a member of the department of psychiatry of the University of Lausanne in Switzerland, noted in 1984 “the importance that depressive symptomatology has taken today as a call for help among female hysterics. . . . It seems that the hysterical woman today has a better chance of a hearing if she presents with a depressive picture, even evoking suicidal ideas.” Although hysteria today is discredited as a diagnosis, it is interesting that older clinicians such as Frei saw it as a diagnosis that trumped depression; he even argued that his patients at Cery Hospital were modeling their symptoms to conform to the new diagnoses. The 1950s and 1960s saw alternative diagnoses to the nervous syndrome come and go, fragments of clinical experience that seemed to make sense to individual physicians but were not more widely taken up because their originators did not have prestigious academic appointments. Take “the housewife syndrome” that Palma Formica proposed in 1962.
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Atkins, Peter. "Two Hands Clapping: Redox Reactions." In Reactions. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199695126.003.0009.
Abstract:
I promised in Reactions 3 and 4 to lead you to the promised land of the modern understanding of oxidation and reduction reactions. This is the section where these two great chemical rivers flow together and acquire great explanatory power and wide applicability. I have already shown that one great class of reactions, those between acids and bases (Reaction 2), takes place by the transfer of one fundamental particle, the proton. I shall now show you that oxidation and reduction reactions all take place by the transfer of another fundamental particle, in this case the proton’s cousin, the electron. Don’t be put off by the thought that in this unification of two great rivers I am embarking on a highly abstract, distant-from-reality account. All I am doing is looking for and presenting the essential step that is involved in these reactions. This is a bit like looking for the core idea of many sports, which is to get a projectile to move into a particular location, be it soccer, baseball shooting, darts, archery, or billiards. I hope you will begin to appreciate in the course of this chapter that when chemists carry out their reactions by stirring, boiling, and mixing, all they are doing is encouraging fundamental particles, in this case electrons but in Reaction 2 protons, to migrate from where they are found to where the chemist wants them to be. Industry does the same coaxing on a massive scale. My aim here is to show you that everything I discussed in Reactions 3 and 4 boils down to the consequences of the transfer of electrons from one species to another. You have already caught a glimpse of that process as we stood together perilously deep inside the blast furnace in Reaction 4 and saw that O2– ions transfer electrons to Fe3+ ions to bring about the reduction of the ore to the metal. Tighten your intellectual seat belt. I intend to develop the very sparse view that oxidation is the loss of electrons and reduction is their gain. That is the austere message to take from this chapter, but I will cloak it in velvet.
Conference papers on the topic "Redox des particules":
1
West, Julia M., Ian G. McKinley, and Simcha Stroes-Gascoyne. "Implications of Microbial Redox Catalysis in Analogue Systems for Repository Safety Cases." In ASME 2009 12th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2009. http://dx.doi.org/10.1115/icem2009-16336.
Abstract:
A detailed assessment of studies of oxidising redox fronts around fractures at depth in otherwise “reducing” environments suggests that the usual explanation, in terms of past disturbances that have resulted in deep penetration of oxidising water, are incompatible with hydrogeological and/or geochemical observations. An alternative hypothesis, microbial catalysis of kinetically slow or hindered reactions involving oxyanions such as sulphate or carbonate, appears potentially more credible. Although still not always taken into account by the geochemical community, the role of microbial metabolism in low temperature geochemistry is supported by the rapidly expanding database on subsurface microbial populations. These populations are demonstrated to be viable and, therefore, could potentially be active at levels close to or below current detection limits in deep geological systems. Indeed, inspection of information available from several analogue studies or repository site characterisation programmes suggests that such activity may explain some of the geochemical anomalies encountered. This paper examines the current (indirect) evidence for microbial redox catalysis in relevant subsurface rock matrix environments and considers the implications that this would have for the development of site understanding — and in particular the identification of factors that may distinguish between different locations during site selection. Further, it examines the wider implications of more extensive roles of microbes in repository systems on the overall post-closure safety case and the need for further focused analogue studies to develop answers to these open questions.
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Arnold, J., S. A. Ansar, U. Maier, and R. Henne. "Insulating and Sealing of SOFC Devices by Plasma Sprayed Ceramic Layers." In ITSC2008, edited by B. R. Marple, M. M. Hyland, Y. C. Lau, C. J. Li, R. S. Lima, and G. Montavon. Verlag für Schweißen und verwandte Verfahren DVS-Verlag GmbH, 2008. http://dx.doi.org/10.31399/asm.cp.itsc2008p0083.
Abstract:
Abstract Solid oxide fuel cells (SOFCs) are one of the options as auxiliary power units (APU) in transportation, e.g. in vehicles or in aircraft. In particular, metal supported SOFCs consisting of metallic frames and substrates coated with plasma sprayed functional layers have shown an excellent stability concerning redox cycling. In order to provide sufficient power, these single cells have to be assembled to stacks. To prevent short-circuiting the frame of each cell has to be electrically insulated from the neighbouring one. For that purpose a ceramic coating is applied on each metal frame by thermal spraying before it is brazed to other stack components. Such layers should at one hand show good wetting and adhesion to the silver based brazing materials. On the other hand it should maintain sufficient electrical resistance even at the fuel cell operating temperature. As the applied solder, which connects the cells and seals the gas manifold simultaneously, is an excellent electrical conductor, it is mandatory to prevent the brazing material from penetrating into the deposit. In this paper a description of the design and experiences with these plasma sprayed insulating layers is given.
3
Vilmos, Józsa, Jacek Kozłowski, Anna Zróbek-Sokolnik, Krzysztof Kozłowski, and Piotr Dynowski. "Classification of the Oxbow Lakes of the Hármas-Körös River and Determination of Ways for Further Exploiting the Various Water Regions in the Light of the Water Framework Directive." In Environmental Engineering. VGTU Technika, 2017. http://dx.doi.org/10.3846/enviro.2017.057.
Abstract:
Hármas-Koros river lies between the mouth of the Tisza and the city Békés. In the nineteenth century, the work of regulatory her bed was made, which resulted in 44 oxbow lakes were created, of which 36 still exist till today. In presented work 14 oxbow lakes was selected and the following objectives were carried out: 1. The classification of oxbow lakes based on selected criteria: the manner and intensity of water exchange, sediment thickness, redox potential, usage, ichtiofouna. 2. The assessment of the state of spawning and its impact on ichtiofauna. 3. Determination the best methods of water management in particular types of oxbow lakes, which could stop their further degradation. The obtained results led to the following conclusions: - Tested oxbow lakes belong to different categories - Anthropogenic factors had a negative effect on the conditions of fish reproduction and survival of their juvenile stages. - The management of fisheries was not a factor differentiating the individual water regions, but had an impact on the ecological status. - For the maintenance and/or improvement of the natural environment of the individual oxbow lakes significant impact may have fishery management, carried out in the following years.
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King, Fraser, Katherine Ikeda-Cameron, Greg Van Boven, Tom Jack, Robert Sutherby, and Robert Worthingham. "In Situ Monitoring of Environmental Conditions for Stress Corrosion Cracking." In 2004 International Pipeline Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/ipc2004-0371.
Abstract:
TransCanada Pipelines have been involved with monitoring environmental conditions at pipe depth for almost 10 years. The purpose of this monitoring is to understand the mechanism of SCC as it occurs in the field and to assist in the development of site-selection models for identifying locations where SCC might be occurring. Monitoring can either be done at many locations along the right-of-way at a given time or continuously at discrete locations in order to observe seasonal variations. A range of environmental parameters can be monitored. Early work focussed on parameters relevant to corrosion, such as soil resistivity, redox potential, temperature, pH, and on- and off-potentials. More recently, parameters relevant to SCC have also been monitored, such as soil CO2 and permeable hydrogen concentrations. In addition, the extent to which these parameters change seasonally has been monitored to determine if the environment is conducive to SCC continuously or whether cracking might only occur at certain times of the year. In terms of implementation, the results of in situ monitoring can be used as part of a larger integrity management program to decide where and when to mitigate SCC. Correlations between soil parameters measured using the portable probe and known SCC sites can be used to identify other susceptible locations or to prioritize different lines for inspection. Seasonal variations at a particular location can be used to derive effective crack growth rates from accelerated laboratory testing in order to determine re-inspection intervals. Examples are provided of both portable and permanent NOVAProbe measurements for low-pH and high-pH SCC.
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Agonafer, Damena D., Edward Chainani, Muhammed E. Oruc, Ki Sung Lee, and Mark A. Shannon. "Study of Alkane Thiols as a Blocking Mechanism for Specific Adsorption for Application of Charge Selective Membrane Transport." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-64678.
Abstract:
Electrodialysis (ED) is an electrochemical process used for separation of ions across perm-selective membranes. ED uses a DC bias to selectively transport ions across membranes for applications ranging from desalination of water to demineralization of fruit juice. The energy cost of ED is due to accumulation of hydroxide and hydronium ions from the electrochemical process of water; additionally there is the cost of using platinum electrodes. This paper addresses the idea of using polycarbonate track etched membrane (PCTE) coated with gold between the membranes to reduce the energy cost and to explore a wider selection of electrode materials. This paper aims to show how thiol monolayers on gold can be used as ideal polarizable electrodes (electrode behaves like a capacitor with only charging current and no faradaic current) for application of potential to the membrane surface double layer. We report the characterization of such monolayers on gold-coated microscope slides. The goal is to control the diffuse layer potential at each membrane-solution interface while at the same time prevent adsorption on the electrode surface and minimize Faradaic activity due to electrolyte and redox species in solution. This lays the groundwork for the application of thiol-modified polycarbonate track-etched membranes for ion-selective transport. The paper proposes the use of electrochemical impedance spectroscopy (EIS) to measure characteristics of gold (Au)-coated membranes and their inherent limitations. In this work, the fabrication of a membrane permeate flow cell is described with the aim of subsequently studying the transport of ions through conductive polycarbonate track etched membrane (PCTE) by interrogating the system using EIS and CV measurements. In particular, we would like to ascertain the voltage range that can be applied to the Au-coated membrane without getting a considerable faradaic activity; the difference between platinum and Au electrode; the effects of different electrolyte concentrations and various applied DC potentials.
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Barbosa, Lucas Lopes, Giovanna Dos Santos Cunha, and João Felipe Dos Santos Souza. "MALÁRIA DURANTE A GESTAÇÃO E ASPECTOS IMUNOLÓGICOS DO HOSPEDEIRO." In I Congresso Brasileiro de Parasitologia Humana On-line. Revista Multidisciplinar em Saúde, 2021. http://dx.doi.org/10.51161/rems/1963.
Abstract:
Introdução: A vasta disposição territorial do plasmódio, parasito causador da malária, ao redor do mundo faz do parasitismo durante a gestação, um grave problema de saúde pública, na qual as gestantes são em particular, vulneráveis ao parasito pela gestação modificar a imunidade, deixando assim a gestante com maior suscetibilidade à contaminação malárica. Objetivo: Elencar os aspectos imunológicos contra a malária, em particular nas gestantes. Material e métodos: Realizou-se uma revisão bibliográfica da literatura disponível, sendo selecionados artigos nas bases de dados SciELO, PUBMED e Biblioteca Virtual em Saúde (BVS), dos últimos 10 anos, utilizando os descritores “malária gestacional” e “aspectos imunológicos na malária”, com artigos em português, empregando critérios de inclusão e exclusão previamente definidos. Resultados: A literatura empregada possibilitou observar a frequência dos casos de malária em mulheres grávidas, na qual confere mudanças na evolução gestacional, causando complicações como hipoglicemias, aborto, parto prematuro, dentre outros. Devido a alteração na imunidade da gestante, a mesma tem uma maior suscetibilidade à infecção, bem como, complicações como a anemia grave e óbito materno, pois diminui a imunidade protetora ao parasito. A defesa contra a malária abrange as respostas celular e humoral, em que linfócitos T são imprescindíveis para estruturação da síntese de anticorpos, o que diminui a suscetibilidade do hospedeiro aos impactos feitos pelos plasmódios, enquanto os linfócitos B secretam anticorpos antimaláricos. Ao longo da sua permanência no sangue, é induzido pelos esporozoítos, uma resposta com produção de anticorpos contra antígenos, na qual a hipergamaglobulinemia se destaca na infecção pelo parasito, por caracterizar um aumento de IgG e IgM. A resposta imune ocorre convenientemente no ciclo eritrocítico, conferindo efetivamente uma resposta contra o parasito. É importante relatar que no baço, fígado e medula óssea acontece o principal mecanismo de combate do organismo, com a fagocitose de merozoítas e eritrócitos parasitados. Conclusão: Existe uma íntima relação entre gestantes e malária devido alteração do seu estado imune, onde essa situação pode ser regulada pela resposta celular ou humoral, sintetizando anticorpos e induzindo mecanismos para combater o parasito, através de linfócitos B e T.
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Al-Raqom, F., and J. F. Klausner. "Reactivity of Iron/Zirconia Powder in Fluidized Bed Thermochemical Hydrogen Production Reactors." In ASME 2012 6th International Conference on Energy Sustainability collocated with the ASME 2012 10th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/es2012-91485.
Abstract:
A fluidized bed reactor has been developed which uses a two-step thermochemical water splitting process with a peak hydrogen production rate of 47 Ncm3/min.gFe at an oxidation temperature of 850°C. Of particular interest, is that a mixture of iron and zirconia powder is fluidized during the oxidation reaction using a steam mass flux of 0.58 g/min-cm2, and the zirconia powder serves to virtually eliminate iron powder sintering while maintaining a high reaction rate. The iron/zirconia powder is mixed with a ratio of 1:2 by apparent volume, equivalent mass ratio, and both iron and zirconia particles are sieved to sizes ranging from 125–355 μm. Fluidized bed reactors are advantageous because they have high reactivity, strong thermal and chemical transport, and tend to be compact. There has been significant interest in developing fluidized bed reactors for solar thermochemical reactors, but sintering of the reactive powder has inhibited their development. The current powder mixture and reactor configuration shows great potential for achieving high hydrogen production rates for operation at high temperature. The experimental investigations for utilizing zirconia as a sintering inhibitor was found to be dependent on the iron and zirconia particle size, particle size distribution and iron/zirconia apparent volume ratio. For example at 650 °C the oxidation of iron powder with a mean particle size of 100 μm and a wide particle size distribution (40–250 μm) mixed with 44 μm zirconia powder with an iron/zirconia apparent volume ratio of 1:1 results in 75–90 % sintering. In all cases when iron is mixed with zirconia, the hydrogen production rate is not affected when compared with the pure iron case. When iron powder is mixed with zirconia, both with a narrow particle size distribution (125–355 μm) the first oxidation step results in 3–7% sintering when the reactions are carried out at temperatures ranging between 840–895 °C. The hydrogen fractional yield is high (94–97%). For subsequent redox reactions, the sintering is totally eliminated at 867 and 895 °C although the hydrogen fractional yield decreases to 27 and 33%, respectively. This study demonstrates that mixing iron with zirconia in an equivalent mass ratio and similar particle size can eliminate sintering in a fluidized bed reactor at elevated temperatures up to 895°C.
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Manokaran, Padmanaban, Fahad Al Rumaithi, Mohamad Bara Adi, and Saeed Khalfan Al Suwaidi. "Effective Front-End Loading Management - Most Occurred Flaws in FEL Execution." In ADIPEC. SPE, 2022. http://dx.doi.org/10.2118/210881-ms.
Abstract:
Abstract Project Management team aims to strive for 100% success all the time. it's no secret that sometimes projects fail due to various reasons. But a project failure doesn't have to be the end of the story. Project failures can often offer valuable lessons for future project planning. Given the magnitude of investment observed in an Upstream Projects, it is necessary to adopt appropriate methods and processes to ensure the economic viability of the projects, as well as to effectively control the fulfilment of scope, schedule, quality and risk mitigation. The oil and gas industry has consistently used the combination of both methodologies of the PMI and IPA in the development of major projects, with particular attention on the front-end loading methodology (FEL), which combines an approach of so-called "rolling wave planning", with a vision of technical and cost integration in the light of other Project execution techniques. Certainly, most of Capital projects had fulfilled all the mandatory Front-End Loading (FEL) requirements set by an organization. However, at sanction gate only very few projects are allowed to proceed for execution, and rest are directed to redo or retrofit the FEL's. This Paper aims to capture the most occurred flaws in FEL execution of Upstream Oil & Gas Projects as below: Over Design & Gold PlatingIncomplete Technology SelectionPoor definition of Brownfield Works & Lack of Interface ManagementUnderstating Infrastructure RequirementsLow Stakeholder EngagementUnresolved Risks & UncertaintiesEstimating ErrorsOverly Optimistic Economics In addition, it also presents recommendations to improve the FEL execution and minimize the potential design changes during Project execution. It can be seen clearly all the above issues are often occurring in most of the Capital projects during FEL execution. These findings can be viewed as a lesson learned approach for all Oil & Gas Upstream capital Projects. This will guide Owners Project Management team better understanding of FEL issues at upfront while developing new projects or executing the FEL phase within budget, on schedule with desired quality.
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Armanini Forte, Alicia, Beatriz Lemos de Almeida, Fernanda Pereira Grein Nunes, and Gleiciane Madalena Simon. "MOBILIDADE E INFRAESTRUTURA NO ESPAÇO PÚBLICO. Avaliação da Caminhabilidade no Entorno da Uniandrade, Curitiba-PR." In Seminario Internacional de Investigación en Urbanismo. Universitat Politècnica de Catalunya, Grup de Recerca en Urbanisme, 2020. http://dx.doi.org/10.5821/siiu.12207.
Abstract:
The term “walkability”, is linked with the new society yearnings to make cities into more sustainable, for the benefit of people and providing more pleasant and inviting urban environments for pedestrians, with guaranteed safety and accessibility conditions. This research started with the recognition of the mobility conditions and infrastructure of the public space, with a main focus on the analysis of sidewalks and crossings of roads and the fulfillment of pedestrian criteria. Subsequently, a geographic area was delimited, in this case the immediate surroundings of a university. The chosen place prioritized a space of urban dynamism, from a large equipment that works as an inducer of growth, densification and traffic generator, in addition, promoting pedestrian traffic. For this territorial cut, the Walkability Index was applied, a tool developed by the Institute of Transport and Development Policies (ITDP Brazil), aiming to measure the characteristics of the urban environment and evaluate them in their relevance to favor displacements on foot. Keywords: Walkability Index, public space, sidewalks, urban infrastructure. O termo “caminhabilidade”, traduzido do inglês “walkability”, está vinculado os novos anseios de criar cidades mais sustentáveis, voltadas para o benefício das pessoas, proporcionando ambientes urbanos mais agradáveis e convidativos aos pedestres. A Uniandrade, como equipamento de grande porte torna-se polo gerador de trânsito de pessoas e veículos, podendo fomentar ainda investimentos na infraestrutura local. O objetivo desta pesquisa é investigar se as condições de caminhabilidade ao redor da Uniandrade são adequadas, utilizando como método o Índice de Caminhabilidade elaborado pelo ITDP Brasil. Este índice se tornou mais adequado por incorporar mais de uma escala de avaliação, com a finalidade de avaliar a condição das calçadas e a relação destas condições com os principais trajetos de caminhada. Diante do processo de elaboração da pesquisa, julgou-se adequado ainda uma avaliação quanto a aplicabilidade do método, clareza nas especificações, facilidade no levantamento dos dados e relevância para o recorte. Como resultado, o recorte analisado foi considerado pouco adequado a caminhabilidade e percebeu-se que esta ferramenta apresenta alta complexidade e precisão de dados, porem foram identificadas limitações ao longo da aplicação. Estas limitações podem ocorrer, também, pela existência de diferentes cenários urbanos possíveis, sendo, portanto, recomendado a percepção particular para cada recorte avaliado. Palavras-chave: índice de caminhabilidade, espaço público, calçadas, infraestrutura urbana.
Reports on the topic "Redox des particules":
1
King and Jack. L51906 The Role of Redox and Corrosion Potentials in the Corrosion of Line Pipe Steel. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), September 2001. http://dx.doi.org/10.55274/r0010374.
Abstract:
A combined lab and field program has been performed to study the external corrosion behaviour of buried linepipe. The overall aim of the project was to attempt to correlate pipe damage with measurable soil properties, in particular the redox potential as measured by buried soil probes. The lab component of the project involved the measurement of weight-loss corrosion rates in three types of soil, under saturated and as-received moisture conditions, and under permanently aerobic, permanently anaerobic or cyclic anaerobic/aerobic redox conditions. The soil conditions and coupon corrosion potentials were monitored during the course of the tests. In the field component of the study, pipe-depth soil properties were monitored using permanent NOVAProbes to measure the redox potential, soil resistivity, pH and temperature. Daily readings were taken at some locations with the aid of a custom-designed datalogger. Corrosion information was obtained from buried weight-loss or electrochemical coupons, from pipe excavations or from data from repeat in-line inspection runs.
2
Thompson. L52114 Efficient use of Cathodic Polarization Criteria. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), January 2005. http://dx.doi.org/10.55274/r0011101.
Abstract:
A series of long term polarization tests were performed to investigate efficient use of the 100mV polarization growth/decay for demonstrating CP effectiveness. Several conclusions were drawn. Absolute time limits for measuring polarization growth or decay could not be justified. Simple extrapolation of polarization growth or decay curves also could not be justified; future extrapolation needs to be mechanistically based. The application of CP can change the local environment at a steel surface including creating passivity. Redox reactions in soils complicate analysis of polarization data. For a particular system at constant applied current, formation and decay rates are similar. However, Initial polarization has less magnitude than subsequent polarizations.
3
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.
Abstract:
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.