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Статті в журналах з теми "Redox of particles":
1
McWhinney, R. D., S. Zhou, and J. P. D. Abbatt. "Redox activity of naphthalene secondary organic aerosol." Atmospheric Chemistry and Physics Discussions 13, no. 4 (April 5, 2013): 9107–49. http://dx.doi.org/10.5194/acpd-13-9107-2013.
Анотація:
Abstract. Chamber secondary organic aerosol (SOA) from low-NOx photooxidation of naphthalene by hydroxyl radical was examined with respect to its redox cycling behaviour using the dithiothreitol (DTT) assay. Naphthalene SOA was highly redox active, consuming DTT at an average rate of 118 ± 14 pmol per minute per μg of SOA material. Measured particle-phase masses of the major previously identified redox active products, 1,2- and 1,4-naphthoquinone, accounted for only 21 ± 3% of the observed redox cycling activity. The redox-active 5-hydroxy-1,4-naphthoquinone was identified as a new minor product of naphthalene oxidation, and including this species in redox activity predictions increased the predicted DTT reactivity to 30 ± 5% of observations. Similar attempts to predict redox behaviour of oxidised two-stroke engine exhaust particles by measuring 1,2-naphthoquinone, 1,4-naphthoquinone and 9,10-phenanthrenequinone predicted DTT decay rates only 4.9 ± 2.5% of those observed. Together, these results suggest that there are substantial unidentified redox-active SOA constituents beyond the small quinones that may be important toxic components of these particles. A gas-to-SOA particle partitioning coefficient was calculated to be (7.0 ± 2.5) × 10−4 m3 μg−1 for 1,4-naphthoquinone at 25 °C. This value suggests that under typical warm conditions, 1,4-naphthoquinone is unlikely to contribute strongly to redox behaviour of ambient particles, although further work is needed to determine the potential impact under conditions such as low temperatures where partitioning to the particle is more favourable. As well, higher order oxidation products that likely account for a substantial fraction of the redox cycling capability of the naphthalene SOA are likely to partition much more strongly to the particle phase.
2
Wei, Chenxi, Yanshuai Hong, Yangchao Tian, Xiqian Yu, Yijin Liu, and Piero Pianetta. "Quantifying redox heterogeneity in single-crystalline LiCoO2 cathode particles." Journal of Synchrotron Radiation 27, no. 3 (March 13, 2020): 713–19. http://dx.doi.org/10.1107/s1600577520002076.
Анотація:
Active cathode particles are fundamental architectural units for the composite electrode of Li-ion batteries. The microstructure of the particles has a profound impact on their behavior and, consequently, on the cell-level electrochemical performance. LiCoO2 (LCO, a dominant cathode material) is often in the form of well-shaped particles, a few micrometres in size, with good crystallinity. In contrast to secondary particles (an agglomeration of many fine primary grains), which are the other common form of battery particles populated with structural and chemical defects, it is often anticipated that good particle crystallinity leads to superior mechanical robustness and suppressed charge heterogeneity. Yet, sub-particle level charge inhomogeneity in LCO particles has been widely reported in the literature, posing a frontier challenge in this field. Herein, this topic is revisited and it is demonstrated that X-ray absorption spectra on single-crystalline particles with highly anisotropic lattice structures are sensitive to the polarization configuration of the incident X-rays, causing some degree of ambiguity in analyzing the local spectroscopic fingerprint. To tackle this issue, a methodology is developed that extracts the white-line peak energy in the X-ray absorption near-edge structure spectra as a key data attribute for representing the local state of charge in the LCO crystal. This method demonstrates significantly improved accuracy and reveals the mesoscale chemical complexity in LCO particles with better fidelity. In addition to the implications on the importance of particle engineering for LCO cathodes, the method developed herein also has significant impact on spectro-microscopic studies of single-crystalline materials at synchrotron facilities, which is broadly applicable to a wide range of scientific disciplines well beyond battery research.
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McWhinney, R. D., S. Zhou, and J. P. D. Abbatt. "Naphthalene SOA: redox activity and naphthoquinone gas–particle partitioning." Atmospheric Chemistry and Physics 13, no. 19 (October 2, 2013): 9731–44. http://dx.doi.org/10.5194/acp-13-9731-2013.
Анотація:
Abstract. Chamber secondary organic aerosol (SOA) from low-NOx photooxidation of naphthalene by hydroxyl radical was examined with respect to its redox cycling behaviour using the dithiothreitol (DTT) assay. Naphthalene SOA was highly redox-active, consuming DTT at an average rate of 118 ± 14 pmol per minute per μg of SOA material. Measured particle-phase masses of the major previously identified redox active products, 1,2- and 1,4-naphthoquinone, accounted for only 21 ± 3% of the observed redox cycling activity. The redox-active 5-hydroxy-1,4-naphthoquinone was identified as a new minor product of naphthalene oxidation, and including this species in redox activity predictions increased the predicted DTT reactivity to 30 ± 5% of observations. These results suggest that there are substantial unidentified redox-active SOA constituents beyond the small quinones that may be important toxic components of these particles. A gas-to-SOA particle partitioning coefficient was calculated to be (7.0 ± 2.5) × 10−4 m3 μg−1 for 1,4-naphthoquinone at 25 °C. This value suggests that under typical warm conditions, 1,4-naphthoquinone is unlikely to contribute strongly to redox behaviour of ambient particles, although further work is needed to determine the potential impact under conditions such as low temperatures where partitioning to the particle is more favourable. Also, higher order oxidation products that likely account for a substantial fraction of the redox cycling capability of the naphthalene SOA are likely to partition much more strongly to the particle phase.
4
Frey, H., A. Beck, X. Huang, J. A. van Bokhoven, and M. G. Willinger. "Dynamic interplay between metal nanoparticles and oxide support under redox conditions." Science 376, no. 6596 (May 27, 2022): 982–87. http://dx.doi.org/10.1126/science.abm3371.
Анотація:
The dynamic interactions between noble metal particles and reducible metal-oxide supports can depend on redox reactions with ambient gases. Transmission electron microscopy revealed that the strong metal-support interaction (SMSI)–induced encapsulation of platinum particles on titania observed under reducing conditions is lost once the system is exposed to a redox-reactive environment containing oxygen and hydrogen at a total pressure of ~1 bar. Destabilization of the metal–oxide interface and redox-mediated reconstructions of titania lead to particle dynamics and directed particle migration that depend on nanoparticle orientation. A static encapsulated SMSI state was reestablished when switching back to purely oxidizing conditions. This work highlights the difference between reactive and nonreactive states and demonstrates that manifestations of the metal-support interaction strongly depend on the chemical environment.
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Lu, Senlin, Teng Ma, Lu Zhang, Yule Feng, Shumin Zhou, Wei Zhang, Shinichi Yonemochi, et al. "Relationships between Mass Level of Allergenic Platanus acerifolia Protein 3 (Pla a3) and Redox Trace Elements in the Size-Resolved Particles in Shanghai Atmosphere." Atmosphere 13, no. 10 (September 21, 2022): 1541. http://dx.doi.org/10.3390/atmos13101541.
Анотація:
Allergenic pollen protein can be released from pollen grains and suspended in the air to cause allergenic reactions. However, the allergenic protein and its relationship with redox trace elements in ambient size-resolved particles has not been reported. Ambient size-resolved particles in Shanghai’s atmosphere were sampled during the Platanus pollen season in the spring season of 2017. Planatus pollen protein 3 (Pla a3) and redox trace elements in the ambient particles were investigated and their relationship was analyzed. Our data demonstrated that the mass level of the Pla a3 in the size-resolved particles ranged from 0.41 ± 0.28 to 7.46 ± 2.23 pg/m3, and decreased with the size range. Mass concentrations (ppb) of crustal elements (Fe, Al, Ca, Mg, Na) in the size-resolved particles ranged from 20.11 ± 9.87 to 1126.22 ± 659.51, while trace elements (V, Cr, Mn, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Cd, Cs, Ba, Pb) varied from 0.05 ± 0.03 to 57.53 ± 19.7. Mass levels of these trace elements decreased according to particle size. The Abundance of redox trace elements, including Fe (R2 = 0.82), Mn (R2 = 0.54), Cu (R2 = 0.61), Ba (R2 = 0.82), and Pb (R2 = 0.82) in the size-resolved particles was significantly related to that of Pla a3, and our data implied redox trace elements might take syngenetic effects on the allergenicity induced by Pla a3 protein.
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Gulin-Sarfraz, Tina, Jawad Sarfraz, Didem Şen Karaman Didem Şen Karaman, Jixi Zhang, Christina Oetken-Lindholm, Alain Duchanoy, Jessica M. Rosenholm, and Daniel Abankwa. "FRET-reporter nanoparticles to monitor redox-induced intracellular delivery of active compounds." RSC Adv. 4, no. 32 (2014): 16429–37. http://dx.doi.org/10.1039/c4ra00270a.
Анотація:
FRET-reporter particles for redox-induced release of active compounds in cells were developed. This particle system allowed following the intracellular cleavage of delivered compounds after particle internalization.
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Su, Yangxin, Xinrong Zhang, Shun Zhang, Shi Fang, Xiuli Fu, and Hongjun Shao. "Relationship between the size composition observed from the photosedimention technique and chromaticity of the fine-grained surface sediments from the modern lakes, Songnen Plain." IOP Conference Series: Earth and Environmental Science 1087, no. 1 (October 1, 2022): 012081. http://dx.doi.org/10.1088/1755-1315/1087/1/012081.
Анотація:
Abstract The relationship between clay particle size in fine-grained sediments and the enrichment of organic matter and the redox degree of their environment is conducive to the judgment and evaluation of the hydrocarbon generation potential of fine-grained sediments. The grain size characteristics of clay particles in the surface fine-grained sediments of Chaersen lake, Delong lake, Hongyuan lake, Lamasi lake, and Zhongnei lake in Songnen Plain are revealed by light sedimentation method. On the basis of the test, the relationship between the particle size of clay particles and the sediment chromaticity is analyzed, and the directivity of chromaticity to the content of organic matter and redox degree of fine-grained sediments is used for the organic content estimation. It is confirmed that the particle size of clay is negatively correlated with its organic matter content and positively correlated with its redox degree. This has important reference significance for discussing the hydrocarbon generation potential and evaluation of Cretaceous lacustrine fine-grained source rocks in the Songliao Basin.
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Zhang, Fen, Qian Yao, Yanling Niu, Yantao Li, Haijun Zhou, Xiaoqi Chen, and Lu Bai. "Preparation of polymeric vesicles via redox-initiated RAFT dispersion polymerization." E3S Web of Conferences 438 (2023): 01020. http://dx.doi.org/10.1051/e3sconf/202343801020.
Анотація:
2-(diisopropylamino) ethyl methacrylate (DIPEMA) and glycidyl methacrylate (GlyMA) were used for the investigation of the redox-initiated reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization, by using poly (ethylene oxide)-4-(4-Cyanopentanoic acid) dithiobenzoate (mPEG-CPADB) as the macro-chain-transfer agent (macro-CTA). The particle growth process study indicated that the particles changed from spheres to worms, and then to vesicles during the polymerization process. The degree of polymerization (DP) of the hydrophobic block P(DIPEMA-co-GlyMA) affected the particle morphology, particle diameter and molecular weight significantly. Pure polymeric vesicles could be obtained when DP was equal to or higher than 60, and with increasing of the DP of the hydrophobic block, the diameter and the molecular weight of the particles both increased.
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Tantra, Ratna, Alex Cackett, Roger Peck, Dipak Gohil, and Jacqueline Snowden. "Measurement of Redox Potential in Nanoecotoxicological Investigations." Journal of Toxicology 2012 (2012): 1–7. http://dx.doi.org/10.1155/2012/270651.
Анотація:
Redox potential has been identified by the Organisation for Economic Co-operation and Development (OECD) as one of the parameters that should be investigated for the testing of manufactured nanomaterials. There is still some ambiguity concerning this parameter, i.e., as to what and how to measure, particularly when in a nanoecotoxicological context. In this study the redox potentials of six nanomaterials (either zinc oxide (ZnO) or cerium oxide (CeO2)) dispersions were measured using an oxidation-reduction potential (ORP) electrode probe. The particles under testing differed in terms of their particle size and dispersion stability in deionised water and in various ecotox media. The ORP values of the various dispersions and how they fluctuate relative to each other are discussed. Results show that the ORP values are mainly governed by the type of liquid media employed, with little contributions from the nanoparticles. Seawater was shown to have reduced the ORP value, which was attributed to an increase in the concentration of reducing agents such as sulphites or the reduction of dissolved oxygen concentration. The lack of redox potential value contribution from the particles themselves is thought to be due to insufficient interaction of the particles at the Pt electrode of the ORP probe.
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Liver, Naomi, and Abraham Nitzan. "Redox properties of small semiconductor particles." Journal of Physical Chemistry 96, no. 8 (April 1992): 3366–73. http://dx.doi.org/10.1021/j100187a035.
Дисертації з теми "Redox of particles":
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Bird, Robert. "pH-responsive, redox-sensitive hollow particles for the repair of load-bearing soft tissue." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/phresponsive-redoxsensitive-hollow-particles-for-the-repair-of-loadbearing-soft-tissue(e9c6a050-ca1c-4413-b276-54fedf8b7e00).html.
Анотація:
This thesis presents an investigation of pH-responsive, redox-sensitive poly(MMA-co- MAA) and poly(EA-co-MAA) hollow particles for the repair of load-bearing soft tissues, such as articular cartilage and the intervertebral disc. Hollow particles continue to attract major interest due to their numerous potential applications. The new method for hollow particle preparation presented in this thesis does not require the use of a colloidal template and is well suited for scaling up. Hollow particles were formed using linear poly(MMA-co-MAA) and poly(EA-co-MAA) aliphatic copolymers synthesised using free-radical chain copolymerisation performed in solution. These copolymers were dissolved in dichloromethane using methanol as a cosolvent and emulsified in water. Diffusion of the methanol into the aqueous phase prompts precipitation of the copolymer at the droplet/water interface. The more hydrophobic copolymers containing less MAA showed improved morphology compared to copolymers containing more MAA. Also, poly(EA-co-MAA) hollow particles had a more spherical morphology than poly(MMA-co-MAA) hollow particles with equivalent MAA contents. This was attributed to the lower Tg of the EA structural monomer, which resulted in more flexible particle shells. Unusually, during potentiometric titration of uncrosslinked hollow particles, the pH of the system decreased with increasing neutralisation. This behaviour is thought to be due to the unfolding of copolymer chains, exposing shielded carboxyl groups. The random structure of the copolymers is believed to be necessary for this behaviour. Crosslinked particles became swollen when the pH was increased using buffers. Concentrated dispersions formed self supporting gels, due to steric confinement, at 5 wt.%. The crosslinking process was performed by functionalising with cystamine using carbodiimide chemistry. This introduced disulphide crosslinks; which could be cleaved under reducing conditions at high pH, dissolving the gels. This ability to reduce the hollow particle shells to their constituent linear copolymer chains gives potential for natural removal from the body via extraction by the renal system. pH-triggered loading and release of a hydrophilic dye using crosslinked hollow particles was demonstrated. The similarity of the particle formation process to traditional solvent evaporation also allowed the loading of a hydrophobic dye. However, these particles were not crosslinked so release following swelling could not be investigated. Cystamine-crosslinked systems suffered from degradation due to thiol-disulphide exchange at high pH (~ pH 8). Crosslinking of one system was performed using 2-amino ethyl methacrylate (AEM). This introduced covalent, vinyl intra-shell crosslinking; which did not break down at high pH. Additional AEM was also used to allow inter-particle UVcrosslinking to form doubly crosslinked (DX) hollow-particle hydrogels. These gels did not re-disperse in buffer. To our knowledge, this is the first example of a covalent hydrogel formed from pH-responsive hollow particles. The DX gels offer improved mechanical properties compared to the singly crosslinked, physical gels. Freeze-dried samples of all of the gels produced during this study showed highly porous structures when observed using SEM. The rapid diffusion of FITC-dextran through a sample of DX gel indicates that these pores were interconnected. This is beneficial as it encourages tissue ingrowth, in addition to allowing the rapid diffusion of nutrients, oxygen and cell waste in vivo.
2
Luo, Wen. "Tuning the redox properties of cobalt particles supported on oxides by an In-between graphene layer." Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAF007/document.
Анотація:
L'interaction métal-support (MSI) joue un rôle important dans la catalyse hétérogène. La compréhension et la modification du MSI sont des étapes essentielles pour développer catalyseurs de haute performance. Dans cette thèse, un nouveau concept, qu’il s’agit de recouvrir le support l'oxyde avec un revêtement mono-couche de graphène, a été proposé pour modifier le MSI. L'influence de la couche de graphène sur les interactions de métal (Co et Co-Pt) - oxyde (ZnO et SiO2) et sur les propriétés d'oxydo-réduction des particules métalliques ont été évaluées via des systèmes catalytiques de modèle. Les résultats ont montré que la mono-couche de graphène peut influencer considérablement les états d'oxydation et les morphologies des Co monométallique et Co-Pt bimétallique par rapport aux ceux résultent d’un dépôt direct sur les oxydes nus. En particulier, par calcination sous vide, le graphène protége Co d'être oxydé par ZnO, ce qui conduit à la formation d’un mélange métallique Co-Pt. Co interagit avec les substrats d'oxydes pour former des particules plates qui sont facilement oxydés par O2 en pression faible, tandis que l'insertion d'une couche intermédiaire de graphène entre la couche supérieure métallique et le supporte d’oxyde entraîne la formation des nanoparticules de Co en état très dispersés, qui sont résistants à l'oxydation. Sous la condition de réduction par H2, le graphène favorise clairement la réduction de Co. La quantité de dépôt de Co, le substrat d'oxyde, la température de calcination et l'environnement ont été prouvés pour pouvoir influencer la stabilité de graphène. Ces résultats ouvrent des nouvelles voies possibles d'utiliser le graphène comme promoteur dans des réactions catalytiques à l'avenirThe metal-support interaction (MSI) plays an important role in heterogeneous catalysis. Understanding and tuning the MSI are essential steps for developing catalysts with high performance. In this thesis, a new concept, which is coating the oxide supports with a single layer graphene, was introduced to modify the MSI. The influence of graphene layer on the metal (Co and Co-Pt) – oxide (ZnO and SiO2) interactions and on the redox properties of metal particles were evaluated through model catalyst systems. The results showed that single layer graphene can significantly influence the oxidation states and morphologies of both mono Co and bimetallic Co-Pt as compared to the one after direct deposition on bare oxides. In particular, under vacuum annealing, graphene protects Co from being oxidized by ZnO and results in Co-Pt metallic mixture. Co interacts with oxide substrates forming flat particles which are easily oxidized by low pressure O2, while insertion of a graphene interlayer between the metal overlayer and the oxide supports leads to the formation of highly dispersed Co nanoparticles, which are resistant to oxidation. Under H2 reduction condition, graphene evidently facilitates the reduction of Co. The deposition amount of Co, the oxide substrate, the annealing temperature and the environment were proved to influence the stability of graphene. These results explore new directions for the possible future of using graphene as a promoter in catalytic reactions
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Gupta, Puneet. "Regenerable metal oxide Composite particles and their use in novel chemical processes." The Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1143225336.
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Bhosale, Sheshanath Vishwanath. "Synthesis of bolaamphiphiles and yoctowells with a porphyrin bottom on aminated silica particles containing long distance photoactive Redox pairs and rigid crust /." [S.l. : s.n.], 2004. http://www.diss.fu-berlin.de/2004/341/index.html.
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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.
Анотація:
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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Yazbek, Lindsey Danese. "Hydrogeochemical Factors Influencing Metal Transport and Transformation in a Stream Impaired by Acid Mine Drainage." Kent State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=kent1564478839556002.
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Paul, Dilip K. "Redox Reactions at Oil-Water Interface by Particle Collision Electroanalysis." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5406.
Анотація:
Particle Collision Electrochemistry (PCE) has gained considerable attention in heterogeneous catalysis, petroleum chemistry and pharmaceutical fields. The PCE refers to a phenomenon in which a particle strikes on an inert electrode surface as a consequence of its Brownian motion and produces a spike of current for the direct oxidation/reduction of the individual particle. This method allows us characterization of individual particles and in-situ study of electrochemical reactions coupled to the particle.
Herein, emulsion droplets were studied by PCE where toluene droplets contained hydrophobic tetrachloro-1,4-benzoquinone (Q). This was investigated as a model system to study the molecular effects that arise due to hydrogen bonding reagents (oleic acid, acetic acid) inside and outside of the droplets. The emulsions were prepared by sonicating toluene-quinone solution with the water phase containing an ionic liquid to provide conductivity to the droplet. Each droplet produced a current spike while colliding with the electrode surface that was held at a potential to reduce tetrachoro-1,4-benzoquinone. In bulk acetonitrile and toluene, tetrachoro-1,4-benzoquinone undergoes a two electron reduction process to form the tetrachloro phenolate di-anion (Q2-). It was shown that the hydrogen bonding affinity of Q2- for acetic acid (pKa = 4.8) was higher than for oleic acid (pKa = 9.9) for both bulk systems (as acetic acid is stronger hydrogen bonding donor than oleic acid). However, the reversed trend was observed in emulsified toluene droplets when studied by PCE. This was attributed to the preferential partition of the carboxylic acids between the two phases in the emulsion. Oleic acid stays inside the droplets due its hydrophobic nature and hydrogen bonding with Q2- takes place inside the droplet. In contrast, solvation of acetic acid by the surrounding water, causes the hydrogen bonding with Q2- to occur significantly less inside the droplet.
Another redox system studied by PCE was hydrophobic ferrocene (Fc) trapped in the toluene droplet to determine the effect of surfactant on the particle size. The diameter determined electrochemically was compared with Dynamic Light Scattering (DSL) measurements. The presence of nonionic surfactant (triton X-100) was observed to affect the droplet’s size easily monitored by PCE. The mediated oxidation of cysteine by the oxidized Fc inside the droplet was investigated at different concentrations of cysteine.
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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.
Анотація:
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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.
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McWhinney, Robert. "A Mechanistic Examination of Redox Cycling Activity in Carbonaceous Particulate Matter." Thesis, 2013. http://hdl.handle.net/1807/35905.
Анотація:
Mechanistic aspects of carbonaceous aerosol toxicity were examined with respect to the ability of particles to catalyse reactive oxygen species-generating redox cycling reactions.
To investigate the role of secondary organic material, we examined two systems. In the first, two-stroke engine exhaust particles were found to increase their ability to catalyse redox cycling in the presence of a reducing agent, dithiothreitol (DTT), when the exhaust was exposed to ozone. This occurred through deposition of redox-active secondary organic aerosol (SOA) onto the particle that was ten times more redox active per microgram than the primary engine particle.
In the second system, naphthalene SOA formed highly redox active particles. Activity was strongly correlated to the amount of the 1,4- and 1,2-naphthoquinone measured in the particle phase. However, these species and the newly quantified naphthalene oxidation product 5-hydroxy-1,4-naphthoquinone accounted for only 30% of the observed DTT decay from the particles. Gas-particle partitioning coefficients suggest 1,4- and 1,2-naphthoquinone are not strong contributors to ambient particle redox activity at 25°C. However, a large number of redox active species are unidentified. Some of these may be highly oxidised products of sufficiently low vapour pressure to be atmospherically relevant.
DTT activity of diesel particles was found to be high per unit mass. The activity was found to be associated with the insoluble fraction as filtration of the particles nearly eliminated DTT decay. Neither methanol nor dichloromethane extracts of diesel particles exhibited redox activity, indicating that the redox active species are associated with the black carbon portion of the particles.
Examination of particle concentration techniques found that use of water condensation to grow and concentrate particles introduced a large organic artefact to the particles. Experiments with concentrated inorganic particles suggest that the source of this artefact is from irreversible uptake of water-soluble volatile organic compounds.
Overall, carbonaceous redox active species can be thought of as a continuum from small, water-soluble species to redox active functionalities on elemental carbon backbones. In addition to clearly defined, quantifiable species, future research may need to consider examining broader chemical classes or redox-active chemical functionalities to overcome the inherent complexity of these constituents.
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Bhosale, Sheshanath Vishwanath [Verfasser]. "Synthesis of bolaamphiphiles and yoctowells with a porphyrin : bottom on aminated silica particles containing long distance photoactive Redox pairs and rigid crust / by Sheshanath Vishwanath Bhosale." 2004. http://d-nb.info/973383240/34.
Частини книг з теми "Redox of particles":
1
Willig, F., K. Schwarzburg, B. Trösken, J. Mahrt, L. Motte, and M. P. Pileni. "nm-Semiconductor Particles and Molecular Aggregates as Redox Species." In Fine Particles Science and Technology, 591–608. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-0259-6_41.
2
Broczkowski, M. E., J. S. Goldik, J. J. Noël, and David Shoesmith. "Influence of Noble Metal Particles on Redox Reactions on Uranium Dioxide Surfaces." In Advances in Science and Technology, 1996–2003. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/3-908158-01-x.1996.
3
Krieger, Anja, and Engelbert Weis. "Ph-Dependent Quenching of Chlorophyll Fluorescence in Isolated PSII Particles: Dependence on the Redox-Potential." In Current Research in Photosynthesis, 563–66. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0511-5_129.
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Nakano, Anna, Jinichiro Nakano, and James Bennett. "In-Situ Microscopic Study of Morphology Changes in Natural Hematite and Cu-Spinel Particles During Cyclic Redox Gas Exposures for Chemical Looping Applications." In The Minerals, Metals & Materials Series, 69–77. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-52192-3_7.
5
Larsen, Kristine. "Science Communication Redux: Returning to the Collision Point." In Particle Panic!, 161–78. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-12206-5_8.
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Srinivasan, Tharun, Pavithra Ashok, Venkatraman Sairam, and Amala Reddy. "Regulating Reactive Oxygen Species in Rheumatoid Arthritis: Insights into Cell Signaling Pathways and Nano-Particles as Carriers." In Reactive Oxygen Species - Advances and Developments [Working Title]. IntechOpen, 2023. http://dx.doi.org/10.5772/intechopen.113191.
Анотація:
Rheumatoid arthritis (RA) is a chronic and debilitating inflammatory condition characterized by joint degradation and permanent disability. Excessive production of reactive oxygen species (ROS) is implicated in RA pathogenesis, leading to oxidative stress and tissue damage. In recent years, nano-particles have emerged as promising carriers for ROS regulation therapies in RA treatment. This review explores the interplay between ROS and RA, emphasizing the importance of cell signaling pathways in ROS control. The potential of nano-particles as targeted drug delivery systems to scavenge excess ROS and restore redox equilibrium within affected cells is discussed. Preclinical studies using ROS-neutralizing nano-particles in RA animal models have shown significant reductions in joint inflammation and cartilage degradation. Clinical trials have further validated the safety and efficacy of nano-particle treatments in RA patients, leading to improved disease activity and joint function. The review highlights the benefits of nano-particle-based ROS control therapies, including improved drug solubility, prolonged drug delivery, reduced systemic side effects, and enhanced specificity for inflamed joints. However, further research is needed to fully understand the intricate mechanisms of ROS management in RA and optimize nano-particle production and delivery. Overall, nano-particle-based ROS control therapy holds great promise for revolutionizing RA treatment and improving the quality of life for affected individuals.
7
Atkins, Peter. "Two Hands Clapping: Redox Reactions." In Reactions. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199695126.003.0009.
Анотація:
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.
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Siqueira, Gilvana P., Lucas V. de Faria, and Rodrigo A. A. Muñoz. "Electrochemistry at additively manufactured electrodes." In Electrochemistry, 504–16. The Royal Society of Chemistry, 2023. http://dx.doi.org/10.1039/bk9781839169366-00504.
Анотація:
This chapter presents a brief guide for those who are interested in the use of additively manufactured (3D printed) electrodes for electroanalysis. We focus on the electrochemistry of electrodes fabricated by the fused deposition modeling (FDM) printing technique using polymeric filaments based on polylactic acid (PLA) containing carbon conductive particles (e.g., graphene, graphite or carbon black). Electrode surface treatment, sources of conductive filaments (commercial and lab-made filaments) and 3D printing parameters aiming at improved electrochemical activity are discussed herein. We show the voltammetric results obtained with common redox probes to investigate the electrochemical activity of such 3D printed electrodes, before and after surface treatment, to illustrate the expected voltammetric data to the readers.
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Jin, Yuteng, and Siddharth Misra. "Multifrequency conductivity and permittivity of porous material containing conductive particles in redox inactive conditions." In Multifrequency Electromagnetic Data Interpretation for Subsurface Characterization, 123–43. Elsevier, 2021. http://dx.doi.org/10.1016/b978-0-12-821439-8.00007-0.
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Ezechi, Ezerie Henry, Augustine Chioma Affam, and Khalida Muda. "Principles of Electrocoagulation and Application in Wastewater Treatment." In Handbook of Research on Resource Management for Pollution and Waste Treatment, 404–31. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-0369-0.ch017.
Анотація:
Electrocoagulation has emerged a reliable technology for the treatment of various wastewaters. Its basic principle depends on the response of water particles to strong electric field in a redox reaction. Oxidation of the anode material releases coagulating agents that form metal hydroxide complexes which neutralize particulate materials to form agglomerates. The agglomerates either settle at the bottom or float to the surface depending on the removal path of the electrocoagulation reactor. The merits of electrocoagulation include minimal sludge generation, minimal operator attention, simple equipment, high pollutant removal capacity, and ease of operation. Therefore, this chapter explores the mechanisms of electrocoagulation, components of electrocoagulation, benefits, and demerits of electrocoagulation. Furthermore, the similarity between electrocoagulation and coagulation is explored. Application of electrocoagulation for the treatment of various wastewaters was explored. Feasibility of electrocoagulation was examined through cost evaluation with other treatment technologies.
Тези доповідей конференцій з теми "Redox of particles":
1
Richter, Sebastian, Stefan Brendelberger, Felix Gersdorf, Tobias Oschmann, and Christian Sattler. "Demonstration Reactor System for the Indirect Solar-Thermochemical Reduction of Redox Particles: The Particle Mix Reactor." In ASME 2019 13th International Conference on Energy Sustainability collocated with the ASME 2019 Heat Transfer Summer Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/es2019-3902.
Анотація:
Abstract In contrast to thermal receivers that provide heat for steam cycles, in solar thermochemistry often receiver-reactors are used, where materials undergo a reaction while being irradiated by concentrated sunlight. When applied to two-step redox cycles, multiple processes take place in such receiver-reactors, though on different time scales. This leads to design compromises and to high technical requirements for the implementation. A concept for an indirect particle-based system for thermochemical cycles was therefore proposed in which the heat required for the reduction of redox particles is provided by inert heat transfer particles that absorb concentrated solar radiation in a dedicated particle receiver. The novel and central component in this indirect system is the particle mix reactor. It functions by mixing the two particle types for heat transfer and establishing a controlled atmosphere under decreased oxygen partial pressures in a common reactor chamber. The design of an experimental setup for demonstration and investigation of the particle mix reactor is presented in this work. Potential operation modes and design options for particle heater, mixing unit and oxygen partial pressure decrease are discussed and illustrated. The selection of a mixer type is based on the homogeneity of the obtained mixture. It is supported by the use of Discrete Element Method (DEM) simulations, which were compared to experimental results from a separate setup. Heat loss estimations for the mixing process in the selected mixer geometry are performed for alumina heat transfer particles and strontium iron oxide redox particles. The components’ geometries, the overall experimental setup design as well as operation steps are presented.
2
Liu, Guangliang, Kang Wang, Peter Oladoye, Mayowa Oladipo, Samuel Ogunsola, and Yong Cai. "Particles-mediated photochemical redox transformation of mercury in water." In Goldschmidt2023. France: European Association of Geochemistry, 2023. http://dx.doi.org/10.7185/gold2023.16996.
3
Brendelberger, Stefan, Jan Felinks, Dominik Kolb, and Christian Sattler. "Particle Conveyer for Solar Thermo-Chemical Processes and Related Solid Heat Recovery Systems." In ASME 2016 10th International Conference on Energy Sustainability collocated with the ASME 2016 Power Conference and the ASME 2016 14th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/es2016-59577.
Анотація:
On the way to a de-carbonized economy by 2050 new technologies have to be developed and deployed into the market. In solar driven thermochemical processes concentrated solar radiation is used as a renewable high temperature heat source to drive a chemical reaction. These processes are promising pathways for the production of gaseous and liquid fuels and therefore they can provide sustainable chemical energy carriers with inherent long-term storage capabilities. Amongst these processes, redox cycles for the production of syngas from water and carbon dioxide received considerable interest due to their high theoretical process efficiencies. In these processes a redox material is reduced using high temperature heat which is provided by concentrated solar radiation. In a second reaction, at considerably lower temperatures, the redox material is oxidized while splitting water or carbon dioxide. One requirement for the design of efficient redox processes is a high recovery rate of the sensible heat of the solid redox material. In recent redox process concepts the use of inert heat transfer particles in combination with a particulate redox material has been proposed. Amongst other benefits this methodology allows to recover heat from the redox material. A corresponding solid-solid heat recovery system is under development. In a single stage the heat recovery unit acts as a co-current heat exchanger. By combining several units and by using a proper flow path a quasi-counter-current heat exchanger can be obtained. Such a heat recovery system requires that particles are lifted at temperatures well above 1100°C. These high temperatures require a simple design, decent thermal insulation and the thermal shielding of all moving parts and engine. The present work is dealing with the development of a respective conveying system which can be operated at the targeted temperatures, while heat losses are prevented as far as possible. A lab scale version of the conveyer is constructed and tested. A numerical model of the conveyer is developed and validated using results of an experimental campaign with particles at 1150°C. The next step in the assessment of the conveyer system is the analysis of the performance of a scale up version. A generic process analysis will be conducted to obtain operational and design requirements of the scale up conveyer. A detailed scale up version is developed accordingly and the validated numerical model is applied to this design to predict the heat losses during the particle lifting and to discuss their impact on the total process performance.
4
FEDUTIK, YU A., YU V. BOKSHITS, and G. P. SHEVCHENKO. "FORMATION OF ULTRADISPERSE BIMETALLIC PARTICLES BY REDOX PROCESSES IN AQUEOUS SOLUTIONS." In Reviews and Short Notes to NANOMEETING-2001. WORLD SCIENTIFIC, 2001. http://dx.doi.org/10.1142/9789812810076_0050.
5
Pan, Feng, and Adam Huang. "Investigation and Measurement of Electrical Transport of Metal Particle Polymer Composites for the Development of MEMS-Based Corrosion Sensor." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-12041.
Анотація:
Recently, our research group has proposed a MEMS-based solid state corrosion sensor based on the carbon black and metal particle polymer composite materials. The chemical and dimensional properties of the particles and polymer matrix will provide the tailorability in sensor sensitivity, selectivity, time response, and operating life-span. This paper will analyze the electrical resistivity of the sensor relative to the percentage of different type of particles in PDMS matrix in order to understand the effect of corrosion mechanism on metal particle polymer composites. This paper will also present the electrical quantification techniques for the micro corrosion sensors, the understanding of which is need for the transduction from corrosion to electronic output. Electronic transduction is the natural form of output due to the redox reactions of the electrochemical corrosion of particles and the electric current generated is directly proportional to the rate of the reaction.
6
Gokon, Nobuyuki, Shingo Takahashi, Hiroki Yamamoto, and Tatsuya Kodama. "New Solar Water-Splitting Reactor With Ferrite Particles in an Internally Circulating Fluidized Bed." In ASME 2007 Energy Sustainability Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/es2007-36063.
Анотація:
The thermal reduction of metal oxides as part of a thermochemical two-step water splitting cycle requires the development of a high temperature solar reactor operating at 1000–1500°C. Direct solar energy absorption by metal-oxide particles provides efficient heat transfer directly to the reaction site. This paper describes experimental results of a windowed thermochemical water-splitting reactor using an internally circulating fluidized bed of the reacting metal-oxide particles under direct solar irradiation. The reactor has a transparent quartz window on the top as aperture. The concentrated solar radiation passes downward through the window and directly heats the internally circulating fluidized bed of metal-oxide particles. Therefore, this reactor needs to be combined with a solar tower or beam down optics. NiFe2O4/m-ZrO2 (Ni-ferrite supported on zirconia) particles is loaded as the working redox material in the laboratory scale reactors, and thermally reduced by concentrated Xe-beam irradiation. In a separate step, the thermally-reduced sample is oxidized back to Ni-ferrite with steam at 1000°C. As the results, the conversion of ferrite reached about 44% of maximum value in the reactor by 1kW of incident solar power. The effects of preheating temperature and particle size of NiFe2O4/m-ZrO2 were tested for thermal reduction of internally circulating fluidized bed in this paper.
7
Sorgenfrei, M., and G. Tsatsaronis. "Exergetic Assessment of a Syngas-Redox (SGR)-Based IGCC Plant for Generating Electricity." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-87288.
Анотація:
Carbon capture from advanced Integrated Gasification Combined-Cycle (IGCC) processes should outperform conventional coal combustion with subsequent CO2 separation in terms of efficiency and CO2 capture rates. This paper provides a thermodynamic assessment, using exergy analysis, of a novel Syngas Redox (SGR) process for generating electricity. The power island of the proposed process uses syngas produced by coal gasification and then cleaned through high-temperature gas desulfurization (HGD). Hematite (Fe2O3) is used as an oxygen carrier to oxidize the syngas. To achieve a closed-cycle operation, the reduced iron particles are first partially re-oxidized with steam and then fully re-oxidized with pressurized air. One advantage of this design is that the resulting hydrogen (using steam in the re-oxidation section) can be utilized within the same plant or be on sold as a secondary product. In the proposed process, diluted hydrogen is combusted in a gas turbine. Heat integration is central to the design. The different requirements of syngas cooling, particle-regeneration, and coal drying necessitated the use of a heat-recovery steam generator (HRSG) supplying steam at three pressure levels. To establish a benchmark, the rate of exergy destruction within the SGR process was compared to a coal-fed Shell gasification IGCC design with Selexol-based pre-combustion capture. Process simulation was undertaken using Aspen Plus and EES (Engineering Equation Solver).
8
Mishra, Ashreet, David Korba, and Like Li. "Numerical Investigation of Thermochemical Energy Extraction in a Moving Packed Bed Oxidation Reactor-Heat Exchanger." In ASME 2023 17th International Conference on Energy Sustainability collocated with the ASME 2023 Heat Transfer Summer Conference. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/es2023-107384.
Анотація:
Abstract Moving packed bed heat exchangers (MPBHXs) are becoming an increasingly attractive option for particle-to-sCO2 heat exchangers (HXs) and integrating thermochemical energy storage based on metal oxide redox cycles with concentrated solar power (CSP) systems can provide significant advantages compared to sensible heat storage systems, such as higher energy storage density, higher working fluid (WF) temperature and potentially lower system costs. This work focuses on computational modeling of a shell-and-plate moving bed oxidation reactor-heat exchanger design that utilizes the exothermic oxidation of metal oxide particles under air flow to enhance thermal transport to sCO2 via both sensible and thermochemical heat exchange. A 2D volume-averaged continuum model is developed by coupling the counter-current air-particle flow, interphase heat transfer, thermochemical oxidation reaction, and species transport in the particle channel with sCO2 flow in the WF channel. The counter-flow particle-sCO2 sensible heat exchanger model is verified with previous numerical models in the literature, whereas the transport-reaction model within the particle channel is adopted from previous literature. For the baseline cases with similar geometry, operating parameters, and particle sizes, the total heat transfer for the TCES based HX was 16.71 kW compared to 4.62 kW for sensible only HX. The maximum extent of oxidation at the particle channel outlet was ∼75%, and the sCO2 outlet temperature was 692°C for reactive particles compared to 595°C for inert particles. A parametric study was also conducted to determine the effects of sCO2 and air flow rates on the temperature, extent of reaction, O2 absorption, and total heat transfer of the HXs.
9
Liu, Peng, Carol Ptacek, David W. Blowes, and Y. Zou Finfrock. "Redox Mapping of Cr(VI) and Cr(III) in Biochar Particles Using Confocal Micro-X-Ray Fluorescence Imaging." In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.1601.
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Kopoleva, E. A., and A. Peltek. "DEVELOPING REDOX-SENSITIVE NANOPARTICLES BASED ON TRITHIOCYANURIC ACID FOR THE TARGET DELIVERY OF BIOLOGICALLY ACTIVE COMPOUNDS." In X Международная конференция молодых ученых: биоинформатиков, биотехнологов, биофизиков, вирусологов и молекулярных биологов — 2023. Novosibirsk State University, 2023. http://dx.doi.org/10.25205/978-5-4437-1526-1-91.
Анотація:
This research work is devoted to the developing of a method for the synthesis of trithiocyanuric acid (TTCA)-based nanoparticles as carriers of low molecular weight antitumour drugs. The presented work describes the method of synthesis of TTCA-based particles, their structural and morphological characterization, their sorption properties, as well as the study of the obtained nanoparticles as systems for in vitro delivery of antitumour drugs on 4T1 and A549 cell lines.
Звіти організацій з теми "Redox of particles":
1
Van Pelt, Christopher. Investigation into Redox-Active Copolymers for use in Polymerization Induced Self-Assembled Particles. Office of Scientific and Technical Information (OSTI), February 2023. http://dx.doi.org/10.2172/1923624.
2
Weimer, Alan W. Particle Flow Solarthermal Redox Process to Split Water. Office of Scientific and Technical Information (OSTI), March 2019. http://dx.doi.org/10.2172/1499254.
3
Shahak, Yosepha, and Donald R. Ort. Physiological Bases for Impaired Photosynthetic Performance of Chilling-Sensitive Fruit Trees. United States Department of Agriculture, May 2001. http://dx.doi.org/10.32747/2001.7575278.bard.
Анотація:
Chilling-sensitivity is an important agricultural problem in both the U.S. and Israel. Most research attention has focused so far on herbaceous crop plants, even though the problem is also acute in the fruit tree industry. Under BARD funding we made substantial progress in identifying the mechanisms involved in the disruption of photosynthesis following a chill in mango. Our investigation with fruit trees has been substantially accelerated by drawing on our knowledge and experience with herbaceous crops. The four original research objectives, focused or discovering the underlying mechanisms of chill-induced inhibition of photosynthesis in fruit trees, and the main achievements are listed below. [1] Separating stomatal from non-stomatal components of chilling on photosynthesis in fruit trees. We found evidence that the dark chill-induced inhibition of photosynthesis in mango was E combination of both stomatal and mesophyll components. [2] Differentiating photo damage from light-induced photo protection of photosystem II (PSII). Dark chilling exacerbate high light photoinhibition, as a result of primary inhibition in the carbor reduction cycle. Nevertheless, in Israeli orchards we observed chronic photoinhibition of PSII photochemistry in the winter. This photo damage was reversible over a few days if sunlight was attenuated with filters or night temperature rose. Practical implications of this finding deserve further investment. Additional achievement was the development of a new biophysical tool to study macro-structural changes of LHCII particles in intact, attached leaves. [3] Determine the role of oxidative stress in the dark-chilling-induced inhibition, with emphasis on oxygen radical scavenging, lipid peroxidation and redox-controlled carbon-cycle enzymes. We found an increase in lipid peroxidation following a dark chill, and partial protective effects or an antioxidant. However, the photoinhibition observed in mango orchards in Israel during the winter did not appear to be a general oxidative stress. [4] Investigate whether chilling interferes with the diurnal and circadian rhythm of gene expression of key photosynthetic proteins as has been shown for chilling-sensitive crop plants. The results indicated that most of the circadian rhythm in photosynthesis was due to reduced lea: internal CO2 concentrations during the subjective night, as a result of rhythmic stomatal closure Chilling-induced interference with circadian timing in mango, does not play the central role in chilling inhibition of photosynthesis that has previously been demonstrated in certain chilling sensitive herbaceous plants. Practical implications of the research achievements are feasible, but require few more years of research.
4
Chefetz, Benny, Baoshan Xing, Leor Eshed-Williams, Tamara Polubesova, and Jason Unrine. DOM affected behavior of manufactured nanoparticles in soil-plant system. United States Department of Agriculture, January 2016. http://dx.doi.org/10.32747/2016.7604286.bard.
Анотація:
The overall goal of this project was to elucidate the role of dissolved organic matter (DOM) in soil retention, bioavailability and plant uptake of silver and cerium oxide NPs. The environmental risks of manufactured nanoparticles (NPs) are attracting increasing attention from both industrial and scientific communities. These NPs have shown to be taken-up, translocated and bio- accumulated in plant edible parts. However, very little is known about the behavior of NPs in soil-plant system as affected by dissolved organic matter (DOM). Thus DOM effect on NPs behavior is critical to assessing the environmental fate and risks related to NP exposure. Carbon-based nanomaterials embedded with metal NPs demonstrate a great potential to serve as catalyst and disinfectors. Hence, synthesis of novel carbon-based nanocomposites and testing them in the environmentally relevant conditions (particularly in the DOM presence) is important for their implementation in water purification. Sorption of DOM on Ag-Ag₂S NPs, CeO₂ NPs and synthesized Ag-Fe₃O₄-carbon nanotubebifunctional composite has been studied. High DOM concentration (50mg/L) decreased the adsorptive and catalytic efficiencies of all synthesized NPs. Recyclable Ag-Fe₃O₄-carbon nanotube composite exhibited excellent catalytic and anti-bacterial action, providing complete reduction of common pollutants and inactivating gram-negative and gram-positive bacteria at environmentally relevant DOM concentrations (5-10 mg/L). Our composite material may be suitable for water purification ranging from natural to the industrial waste effluents. We also examined the role of maize (Zeamays L.)-derived root exudates (a form of DOM) and their components on the aggregation and dissolution of CuONPs in the rhizosphere. Root exudates (RE) significantly inhibited the aggregation of CuONPs regardless of ionic strength and electrolyte type. With RE, the critical coagulation concentration of CuONPs in NaCl shifted from 30 to 125 mM and the value in CaCl₂ shifted from 4 to 20 mM. This inhibition was correlated with molecular weight (MW) of RE fractions. Higher MW fraction (> 10 kDa) reduced the aggregation most. RE also significantly promoted the dissolution of CuONPs and lower MW fraction (< 3 kDa) RE mainly contributed to this process. Also, Cu accumulation in plant root tissues was significantly enhanced by RE. This study provides useful insights into the interactions between RE and CuONPs, which is of significance for the safe use of CuONPs-based antimicrobial products in agricultural production. Wheat root exudates (RE) had high reducing ability to convert Ag+ to nAg under light exposure. Photo-induced reduction of Ag+ to nAg in pristine RE was mainly attributed to the 0-3 kDa fraction. Quantification of the silver species change over time suggested that Cl⁻ played an important role in photoconversion of Ag+ to nAg through the formation and redox cycling of photoreactiveAgCl. Potential electron donors for the photoreduction of Ag+ were identified to be reducing sugars and organic acids of low MW. Meanwhile, the stabilization of the formed particles was controlled by both low (0-3 kDa) and high (>3 kDa) MW molecules. This work provides new information for the formation mechanism of metal nanoparticles mediated by RE, which may further our understanding of the biogeochemical cycling and toxicity of heavy metal ions in agricultural and environmental systems. Copper sulfide nanoparticles (CuSNPs) at 1:1 and 1:4 ratios of Cu and S were synthesized, and their respective antifungal efficacy was evaluated against the pathogenic activity of Gibberellafujikuroi(Bakanae disease) in rice (Oryza sativa). In a 2-d in vitro study, CuS decreased G. fujikuroiColony- Forming Units (CFU) compared to controls. In a greenhouse study, treating with CuSNPs at 50 mg/L at the seed stage significantly decreased disease incidence on rice while the commercial Cu-based pesticide Kocide 3000 had no impact on disease. Foliar-applied CuONPs and CuS (1:1) NPs decreased disease incidence by 30.0 and 32.5%, respectively, which outperformed CuS (1:4) NPs (15%) and Kocide 3000 (12.5%). CuS (1:4) NPs also modulated the shoot salicylic acid (SA) and Jasmonic acid (JA) production to enhance the plant defense mechanisms against G. fujikuroiinfection. These results are useful for improving the delivery efficiency of agrichemicals via nano-enabled strategies while minimizing their environmental impact, and advance our understanding of the defense mechanisms triggered by the NPs presence in plants.
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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.
Анотація:
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.