Gotowe bibliografie tematyczne / Electric field-induced chemical reaction

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Gotowa bibliografia na temat „Electric field-induced chemical reaction”

Autor: Grafiati

Data publikacji: 6 września 2023

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Artykuły w czasopismach na temat "Electric field-induced chemical reaction"

Huang, Xiaoyan, Chun Tang, Jieqiong Li, Li-Chuan Chen, Jueting Zheng, Pei Zhang, Jiabo Le i in. "Electric field–induced selective catalysis of single-molecule reaction". Science Advances 5, nr 6 (czerwiec 2019): eaaw3072. http://dx.doi.org/10.1126/sciadv.aaw3072.

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Oriented external electric fields (OEEFs) offer a unique chance to tune catalytic selectivity by orienting the alignment of the electric field along the axis of the activated bond for a specific chemical reaction; however, they remain a key experimental challenge. Here, we experimentally and theoretically investigated the OEEF-induced selective catalysis in a two-step cascade reaction of the Diels-Alder addition followed by an aromatization process. Characterized by the mechanically controllable break junction (MCBJ) technique in the nanogap and confirmed by nuclear magnetic resonance (NMR) in bottles, OEEFs are found to selectively catalyze the aromatization reaction by one order of magnitude owing to the alignment of the electric field on the reaction axis. Meanwhile, the Diels-Alder reaction remained unchanged since its reaction axis is orthogonal to the electric fields. This orientation-selective catalytic effect of OEEFs reveals that chemical reactions can be selectively manipulated through the elegant alignment between the electric fields and the reaction axis.

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Lv, Jieyao, Ruiqin Sun, Qifan Yang, Pengfei Gan, Shiyong Yu i Zhibing Tan. "Research on Electric Field—Induced Catalysis Using Single—Molecule Electrical Measurement". Molecules 28, nr 13 (24.06.2023): 4968. http://dx.doi.org/10.3390/molecules28134968.

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The role of catalysis in controlling chemical reactions is crucial. As an important external stimulus regulatory tool, electric field (EF) catalysis enables further possibilities for chemical reaction regulation. To date, the regulation mechanism of electric fields and electrons on chemical reactions has been modeled. The electric field at the single-molecule electronic scale provides a powerful theoretical weapon to explore the dynamics of individual chemical reactions. The combination of electric fields and single-molecule electronic techniques not only uncovers new principles but also results in the regulation of chemical reactions at the single-molecule scale. This perspective focuses on the recent electric field-catalyzed, single-molecule chemical reactions and assembly, and highlights promising outlooks for future work in single-molecule catalysis.

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Kumar, S., P. Kumar i R. Pratap. "Reliability Failure in Microelectronic Interconnects by Electric Current Induced Chemical Reaction". IOP Conference Series: Materials Science and Engineering 1206, nr 1 (1.11.2021): 012026. http://dx.doi.org/10.1088/1757-899x/1206/1/012026.

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Abstract The electric field-induced chemical reaction in Cr thin film by a micro/nano-probe has been recently reported with detailed characterization. Although the phenomenon is employed for micro-nano fabrication, this can act as a reliability failure, where Cr is used as an adhesion layer or main interconnects in microelectronic circuits. Here, we present an investigation on the role of electric current density for such failure using a specifically designed sample. A 100 μm width and 100 nm thin Cr film is deposited perpendicular to the Pt film of similar dimensions. The anode probe (20 μm diameter) is positioned onto the Pt film, whereas the cathode probe onto the Cr film. It is observed that the chemical reaction, for an applied voltage, initiates at the edge of the Pt film and not at the cathode probe. The localized chemical reaction causes to damage the interconnection line. The analysis based on the COMSOL multiphysics simulation illustrates that the chemical reaction evolves at the high current density locations. The study also builds a fundamental understanding of the mechanism of evolution of patterning by electric field-induced chemical reactions.

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Wang, Nan, i Laurence Weatherley. "Electric field-intensified chemical processes and reaction chemistry". Current Opinion in Chemical Engineering 39 (marzec 2023): 100895. http://dx.doi.org/10.1016/j.coche.2022.100895.

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Kaplunenko, Volodymyr, i Mykola Kosinov. "Electric field - induced catalysis. Laws of field catalysis". InterConf, nr 26(129) (18.10.2022): 332–51. http://dx.doi.org/10.51582/interconf.19-20.10.2022.037.

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Abstract.The article explores a new type of catalysis - electric field catalysis. The laws of field catalysis are given. The characteristics of the electric field are determined, which set the values of the characteristics of the field catalysis. Field catalysis and field catalyst do not fit into the traditional definition of catalysis and catalyst, which may require a revision of the terminology of catalysis. The field is a more versatile catalyst compared to material catalysts, both in terms of its application to a wider range of chemical reactions, and in the ability to control the rate and selectivity. It is shown that a common donor-acceptor mechanism of catalysis is realized in heterogeneous and field catalysis. Generalized formulas are obtained, from which, as partial results, the laws of heterogeneous and field catalysis follow. New definitions of catalyst and field catalysis are given. The class of material catalysts has been expanded and supplemented with field catalysts.

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Deng, Jinxiang, Mengjie Li, Yakun Tian, Zhijun Zhang, Lingling Wu i Lin Hu. "Using Electric Field to Improve the Effect of Microbial-Induced Carbonate Precipitation". Sustainability 15, nr 7 (28.03.2023): 5901. http://dx.doi.org/10.3390/su15075901.

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The precipitation of calcium carbonate induced by Sporosarcina pasteurii (S. pasteurii) has garnered considerable attention as a novel rock and soil reinforcement technique. The content and structure of calcium carbonate produced through this reaction play a crucial role in determining the rocks’ and soil’s reinforcement effects in the later stages. Different potential gradients were introduced during the bacterial culture process to enhance the performance of the cementation and mineralization reactions of the bacterial solution to investigate the effects of electrification on the physical and chemical characteristics, such as the growth and reproduction of S. pasteurii. The results demonstrate that the concentration, activity, and number of viable bacteria of S. pasteurii were substantially enhanced under an electric field, particularly the weak electric field generated by 0.5 V/cm. The increased number of bacteria provides more nucleation sites for calcium carbonate deposition. Moreover, as the urease activity increased, the calcium carbonate content generated under an electric potential gradient of 0.5 V/cm surpassed that of other potential gradient groups. The growth rate increased by 9.78% compared to the calcium carbonate induced without electrification. Significantly, the suitable electric field enhances the crystal morphology of calcium carbonate and augments its quantity, thereby offering a novel approach for utilizing MICP in enhancing soil strength, controlling water pollution, and mitigating seepage. These findings elevate the applicability of microbial mineralization in engineering practices.

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Barmina, I., R. Valdmanis, M. Zake, H. Kalis, M. Marinaki i U. Strautins. "Magnetic Field Control of Combustion Dynamics". Latvian Journal of Physics and Technical Sciences 53, nr 4 (1.08.2016): 36–47. http://dx.doi.org/10.1515/lpts-2016-0027.

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AbstractExperimental studies and mathematical modelling of the effects of magnetic field on combustion dynamics at thermo-chemical conversion of biomass are carried out with the aim of providing control of the processes developing in the reaction zone of swirling flame. The joint research of the magnetic field effect on the combustion dynamics includes the estimation of this effect on the formation of the swirling flame dynamics, flame temperature and composition, providing analysis of the magnetic field effects on the flame characteristics. The results of experiments have shown that the magnetic field exerts the influence on the flow velocity components by enhancing a swirl motion in the flame reaction zone with swirl-enhanced mixing of the axial flow of volatiles with cold air swirl, by cooling the flame reaction zone and by limiting the thermo-chemical conversion of volatiles. Mathematical modelling of magnetic field effect on the formation of the flame dynamics confirms that the electromagnetic force, which is induced by the electric current surrounding the flame, leads to field-enhanced increase of flow vorticity by enhancing mixing of the reactants. The magnetic field effect on the flame temperature and rate of reactions leads to conclusion that field-enhanced increase of the flow vorticity results in flame cooling by limiting the chemical conversion of the reactants.

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Shamshuddin, M. D., Thirupathi Thumma i S. R. Mishra. "Thermo-Solutal Chemically Reacting Micropolar Fluid Past a Permeable Stretching Porous Sheet". Defect and Diffusion Forum 392 (kwiecień 2019): 42–59. http://dx.doi.org/10.4028/www.scientific.net/ddf.392.42.

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The boundary layer flow, heat and mass transfer over a permeable stretching sheet due to a chemically reacting micropolar fluid with slip and convective boundary conditions have been analyzed. Transverse magnetic field clubbed with electric field is also considered for the sake of brevity. Governing nonlinear coupled PDEs are transformed to nonlinear ODEs with the use of suitable similarity transformation. However, analytical solutions to these transformed equations are not useful therefore; numerical solution is carried out using Runge-Kutta fourth order with shooting technique. The characteristics of the embedded parameters are obtained and presented through graphs. Validation of the proposed work with earlier established results are shown in tables and these are in good agreement. From the careful observation the major outcomes are: induced magnetic field decelerates the flow, enhances the thickness of thermal boundary layer temperature whereas applied electric field decelerates the thickness of thermal boundary layer. Both electric field and slip parameter accelerates the angular momentum. Temperature and concentration magnitudes are accelerated at the sheet with an increase of slip parameter. Furthermore, Schmidt number and first order chemical reaction reduces the concentration boundary layer thickness. PACS Number: 05.45-a; 05.70-Ce.

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Gryn'ova, Ganna, i Michelle L. Coote. "Directionality and the Role of Polarization in Electric Field Effects on Radical Stability". Australian Journal of Chemistry 70, nr 4 (2017): 367. http://dx.doi.org/10.1071/ch16579.

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Accurate quantum-chemical calculations are used to analyze the effects of charges on the kinetics and thermodynamics of radical reactions, with specific attention given to the origin and directionality of the effects. Conventionally, large effects of the charges are expected to occur in systems with pronounced charge-separated resonance contributors. The nature (stabilization or destabilization) and magnitude of these effects thus depend on the orientation of the interacting multipoles. However, we show that a significant component of the stabilizing effects of the external electric field is largely independent of the orientation of external electric field (e.g. a charged functional group, a point charge, or an electrode) and occurs even in the absence of any pre-existing charge separation. This effect arises from polarization of the electron density of the molecule induced by the electric field. This polarization effect is greater for highly delocalized species such as resonance-stabilized radicals and transition states of radical reactions. We show that this effect on the stability of such species is preserved in chemical reaction energies, leading to lower bond-dissociation energies and barrier heights. Finally, our simplified modelling of the diol dehydratase-catalyzed 1,2-hydroxyl shift indicates that such stabilizing polarization is likely to contribute to the catalytic activity of enzymes.

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Bunker, Ian, Ridwan Tobi Ayinla i Kun Wang. "Single-Molecule Chemical Reactions Unveiled in Molecular Junctions". Processes 10, nr 12 (3.12.2022): 2574. http://dx.doi.org/10.3390/pr10122574.

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Understanding chemical processes at the single-molecule scale represents the ultimate limit of analytical chemistry. Single-molecule detection techniques allow one to reveal the detailed dynamics and kinetics of a chemical reaction with unprecedented accuracy. It has also enabled the discoveries of new reaction pathways or intermediates/transition states that are inaccessible in conventional ensemble experiments, which is critical to elucidating their intrinsic mechanisms. Thanks to the rapid development of single-molecule junction (SMJ) techniques, detecting chemical reactions via monitoring the electrical current through single molecules has received an increasing amount of attention and has witnessed tremendous advances in recent years. Research efforts in this direction have opened a new route for probing chemical and physical processes with single-molecule precision. This review presents detailed advancements in probing single-molecule chemical reactions using SMJ techniques. We specifically highlight recent progress in investigating electric-field-driven reactions, reaction dynamics and kinetics, host–guest interactions, and redox reactions of different molecular systems. Finally, we discuss the potential of single-molecule detection using SMJs across various future applications.

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Rozprawy doktorskie na temat "Electric field-induced chemical reaction"

Wang, Mu. "On the electric-field-induced responses of charged spherical colloids in uncharged hydrogels and the anomalous viscosity of polymer-nanocomposite melts". Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21951.

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Colloidal particles dispersed in complex fluids such as hydrogels and polymer melts are important because nano-scale inclusions often impart unexpected and commercially attractive changes in the dispersed phase. Future development of these colloidal composites, and diagnostics to characterize their microstructure, demand a sound understanding of micro-scale dynamics. Accordingly, this thesis addresses (i) the steady and dynamic electric-field-induced displacements of spherical colloidal particles embedded in hydrogels, and (ii) the anomalous viscosity reduction of polymer-nanocomposite melts. The first problem is undertaken by solving a multi-phase electrokinetic model that quantifies how the viscoelasticity, compressibility, and hydrodynamic permeability of the hydrogel skeleton, and physicochemical properties of the inclusions, modulate the particle dynamics and electroacoustic responses. For the second problem, a hydrodynamic model is developed, and its analytical solution and numerical extension are adopted to interpret recent experiments in the literature where the bulk viscosity decreases anomalously with increasing particle volume fraction.
Les particules colloïdales dispersées dans les fluides complexes comme les hydrogels et des fontes de polymères sont importantes parce que les inclusions à nano-échelle répandent souvent des changements inattendus et commercialement intéressants dans la phase dispersée. Les développements futurs de ces composites colloïdales et des diagnostiques pour caractériser leur microstructure, demande une bonne compréhension de la dynamique à micro-échelle. En conséquence, cette thèse porte sure (i) la progression régulière et dynamique des déplacements de particules colloïdales sphériques embarqués dans des hydrogels induits par le champ électrique, et (ii) la réduction anormale de la viscosité des fontes en polymères nanocomposites. Le premier problème est entrepris par la résolution d'un modèle électrocinétique à multiple phases qui quantifie de façon où la viscoélasticité, de compression, la perméabilité hydrodynamiques de squelette d'hydrogel et des propriétés physico-chimiques des inclusions, et de moduler la dynamique des particules et réponses électroacoustiques. Pour le deuxième problème, un modèle hydrodynamique est développé, sa solution analytique et son extension numérique sont adoptées pour interpréter les expériences récentes en littérature où la plus grande viscosité diminue anormalement avec l'augmentation du volume fraction des particules.

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Rodgers, Christopher T. "Magnetic field effects in chemical systems". Thesis, University of Oxford, 2007. http://ora.ox.ac.uk/objects/uuid:f5878b88-c5ba-4cbd-83af-857431aef66e.

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Magnetic fields influence the rate and/or yield of chemical reactions that proceed via spin correlated radical pair intermediates. The field of spin chemistry centres around the study of such magnetic field effects (MFEs). This thesis is particularly concerned with the effects of the weak magnetic fields B₀ ~ 1mT relevant in the ongoing debates on the mechanism by which animals sense the geomagnetic field and on the putative health effects of environmental electromagnetic fields. Relatively few previous studies have dealt with such weak magnetic fields. This thesis presents several new theoretical tools and applies them to interpret experimental measurements. Chapter 1 surveys the development and theory of spin chemistry. Chapter 2 introduces the use of Tikhonov and Maximum Entropy Regularisation methods as a new means of analysing MARY field effect data. These are applied to recover details of the diffusive motion of reacting pyrene and N,N-dimethylaniline radicals. Chapter 3 gives a fresh derivation and appraisal of an approximate, semiclassical approach to MFEs. Monte Carlo calculations allow the elucidation of several "rules of thumb" for interpreting MFE data. Chapter 4 discusses recent optically-detected zero-field EPR measurements, adapting the gamma-COMPUTE algorithm from solid state NMR for their interpretation. Chapter 5 explores the role of RF polarisation in producing MFEs. The breakdown in weak fields of the familiar rotating frame approximation is analysed. Chapter 6 reviews current knowledge and landmark experiments in the area of animal magnetoreception. The origins of the sensitivity of European robins Erithacus rubecula to the Earth’s magnetic field are given particular attention. In Chapter 7, Schulten and Ritz’s hypothesis that avian magnetoreception is founded on a radical pair mechanism (RPM) reaction is appraised through calculations in model systems. Chapter 8 introduces quantitative methods of analysing anisotropic magnetic field effects using spherical harmonics. Chapter 9 considers recent observations that European robins may sometimes be disoriented by minuscule RF fields. These are shown to be consistent with magnetoreception via a radical pair with no (effective) magnetic nuclei in one of the radicals.

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Creazzo, Fabrizio. "Oxygen evolution reaction at cobalt oxides/water interfaces : heterogeneous electrocatalysis by DFT-MD simulations & metadynamics Ab initio molecular dynamics study of an aqueous NaCl solution under an electric field Ionic diffusion and proton transfer in aqueous solutions of alkali metal salts Ionic Diffusion and Proton Transfer in Aqueous Solutions under an Electric Field: State-of-The-Art Ionic diffusion and proton transfer of MgCl2 and CaCl2 aqueous solutions: an ab initio study under electric field DFT-MD of the (110)-Co 3 O 4 cobalt oxide semiconductor in contact with liquid water, preliminary chemical and physical insights into the electrochemical environment Enhanced conductivity of water at the electrified air–water interface: a DFT-MD characterization Ions tune interfacial water structure and modulate hydrophobic interactions at silica surfaces". Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASE012.

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Dans cette thèse, des simulations DFT-MD couplées à des techniques inno-vantes de métadynamique, sont appliquées pour acquérir une compréhensionglobale des interfaces aqueuses d'oxyde de cobalt Co3O4 et CoO(OH) dansla catalyse de la réaction d'évolution de l'oxygène (OER), et ainsi éventuellement aider à la conception de nouveaux catalyseurs basés sur des matériaux non précieux, un domaine clé de la recherche scientifique et technologique, particulièrement important pour l'économie de l'hydrogène, pour les technologies vertes dans une période de temps avec une demande toujours plus croissanteen énergie verte. Dans cette thèse, nous révélons étape par étape les mécanismes de l'OER sur les électrocatalyseurs aqueux d'oxyde de cobalt Co3O4 etCoO(OH) via de nouvelles techniques de métadynamique.Jusqu'à présent, la littérature n'a jamais pris en compte les modificationsau niveau atomique de la structure des électrodes ainsi que de l'eau interfaciale dans leur modélisation des processus OER. Ce manque de connaissances représente clairement un obstacle important au développement de catalyseurs améliorés, qui pourrait être surmonté en utilisant des méthodes capables de suivre les caractéristiques catalytiques de l'OER à l'échelle atomique. Pour la première fois, nous montrons combien il est important de prendre en considération la présence de l'environnement aqueux dans la caractérisation structurale des surfaces du catalyseur, c'est-à-dire (110)-Co3O4 et (0001)-CoO(OH) dans ce travail. Une caractérisation détaillée des propriétés chimiques et physiques des interfaces aqueuses est fournie (la structure, la dynamique, la spectroscopie, le champ électrique), pour les surfaces (110)-Co3O4 et (0001)-CoO(OH) en contact avec l'eau liquide.Une étude détaillée de l'OER est présentée non seulement du point de vue descatalyseurs, mais aussi en abordant le rôle de l'environnement de l'eau dans leprocessus catalytique, ce qui n'a pas été fait auparavant dans la littérature. En conséquence, l'OER en phase gazeuse et en phase liquide sont étudiés ici auxinterfaces aqueuses (110)-Co3O4 et (0001)-CoO(OH) en adoptant une nouvelleapproche de métadynamique d'échantillonnage amélioré, capable d'identifieret caractériser les mécanismes de réaction chimique et d'intégrer pleinement lerôle des degrés de liberté du solvant, permettant ainsi de dévoiler des réactivités chimiques d'une complexité remarquable. L'énergétique, la cinétique et la thermodynamique derrière l'OER sont donc trouvées à ces surfaces d'oxyde de cobalt à l'interface avec l'eau
In this thesis, DFT-MD simulations, coupled with state-of-the-art metadynamics techniques, are applied to gain a global understanding of Co3O4 and CoO(OH) cobalt oxide aqueous interfaces in catalyzing the oxygen evolution reaction (OER), and hence possibly help in the design of novel catalysts basedon non-precious materials, a current key field of research in science and technology, especially of importance for the hydrogen economy, for green technology in a period of time with an ever more growing demand in green-energy. In this thesis, we step-by-step reveal the OER mechanisms on spinel Co3O4 andCoO(OH) cobalt aqueous electrocatalysts carefully and rationally via novelmetadynamics techniques.Up to now, the literature has never taken into account the atomistic modifications on the electrode structure as well as on the interfacial water into their modeling of OER processes. Such lack of knowledge clearly represents a significant hurdle toward the development of improved catalysts, which couldbe overcome by employing methods able to track the catalytic features of theOER at the atomistic scale. For the first time, we show how important itis to take into consideration the presence of the liquid water environment inthe structural characterization of catalyst surfaces, i.e. for (110)-Co3O4 and(0001)-CoO(OH) in this work. A detailed characterization of chemical andphysical properties of the aqueous interfaces is provided (i.e. structure, dynamics, spectroscopy, electric field), for the (110)-Co3O4 and (0001)-CoO(OH)aqueous surfaces.A study of the OER is presented not only by looking at the catalysts, butalso by addressing the role of the water environment in the catalytic process,not done before in literature. Accordingly, both gas-phase and liquid-phaseOER are here investigated at the (110)-Co3O4 and (0001)-CoO(OH) adoptinga novel enhanced sampling metadynamics approach able to address a widerange of chemical reaction mechanisms and to fully include the role of thesolvent degrees of freedom, allowing to unveil reaction networks of remarkablecomplexity. The energetics, kinetics and thermodynamics behind the OER aretherefore found at these cobalt oxide surfaces

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Bull, James. "Application of Quantum Mechanics to Fundamental Interactions in Chemical Physics: Studies of Atom-Molecule and Ion-Molecule Interactions Under Single-Collision Conditions: Crossed Molecular Beams; Single-Crystal Mössbauer Spectroscopy: Microscopic Tensor Properties of ⁵⁷Fe Sites in Inorganic Ferrous High-Spin Compounds". Thesis, University of Canterbury. Department of Chemistry, 2010. http://hdl.handle.net/10092/4292.

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As part of this project and in preparation for future experimental studies of gas-phase ion-molecule reactions, extensive modification and characterization of the crossed molecular beam machine in the Department of Chemistry, University of Canterbury has been carried out. This instrument has been configured and some preliminary testing completed to enable the future study of gas-phase ion-molecule collisions of H⁺₃ and Y⁻ (Y = F, Cl, Br) with dipole-oriented CZ₃X (Z = H, F and X = F, Cl, Br). Theoretical calculations (ab initio and density functional theory) are reported on previously experimentally characterized Na + CH₃NO₂, Na + CH₃NC, and K + CH₃NC systems, and several other systems of relevance. All gas-phase experimental and theoretical studies have the common theme of studying collision orientation dependence of reaction under singlecollision conditions. Experimental measurements, theoretical simulations and calculations are also reported on some selected ferrous (Fe²⁺) high-spin (S=2) crystals, in an attempt to resolve microscopic contributions of two fundamental macroscopic tensor properties: the electric-field gradient (efg); and the mean square displacement (msd) in the case when more than one symmetry related site of low local point-group symmetry contributes to the same quadrupole doublet. These determinations have been made using the nuclear spectroscopic technique of Mössbauer spectroscopy, and complemented with X-ray crystallographic measurements.

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Durbeej, Bo. "Quantum Chemical Studies of Protein-Bound Chromophores, UV-Light Induced DNA Damages, and Lignin Formation". Doctoral thesis, Uppsala University, Quantum Chemistry, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4531.

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Quantum chemical methods have been used to provide a better understanding of the photochemistry of astaxanthin and phytochromobilin; the photoenzymic repair of UV-light induced DNA damages; and the formation of lignin.

The carotenoid astaxanthin (AXT) is responsible for the colouration of lobster shell. In solution, the electronic absorption spectra of AXT peak in the 470-490 nm region, corresponding to an orange-red colouration. Upon binding to the lobster-shell protein-complex α-crustacyanin, the absorption maximum is shifted to 632 nm, yielding a slate-blue colouration. Herein, the structural origin of this bathochromic shift is investigated on the basis of recent experimental work.

The tetrapyrrole phytochromobilin (PΦB) underlies the photoactivation of the plant photoreceptor phytochrome. Upon absorption of 660-nm light, PΦB isomerizes from a C15-Z,syn configuration (in the inactive form of the protein) to C15-E,anti (in the active form). In this work, a reaction mechanism for this isomerization is proposed.

DNA photolyases are enzymes that repair DNA damages resulting from far-UV-light induced [2+2] cycloaddition reactions involving pyrimidine nucleobases. The catalytic activity of these enzymes is initiated by near-UV and visible light, and is governed by electron transfer processes between a catalytic cofactor of the enzyme and the DNA lesions. Herein, an explanation for the experimental observation that the repair of cyclobutane pyrimidine dimers (CPD) – the major type of lesion – proceeds by electron transfer from the enzyme to the dimer is presented. Furthermore, the formation of CPD is studied.

Lignin is formed by dehydrogenative polymerization of hydroxycinnamyl alcohols. A detailed understanding of the polymerization mechanism and the factors controlling the outcome of the polymerization is, however, largely missing. Quantum chemical calculations on the initial dimerization step have been performed in order to gain some insight into these issues.

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Jose, Davis. "Dynamics of the B-A transition of DNA double helices". Doctoral thesis, [S.l.] : [s.n.], 2005. http://webdoc.sub.gwdg.de/diss/2005/jose/jose.pdf.

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Thakore, Vaibhav. "Nonlinear dynamic modeling, simulation and characterization of the mesoscale neuron-electrode interface". Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5529.

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Extracellular neuroelectronic interfacing has important applications in the fields of neural prosthetics, biological computation and whole-cell biosensing for drug screening and toxin detection. While the field of neuroelectronic interfacing holds great promise, the recording of high-fidelity signals from extracellular devices has long suffered from the problem of low signal-to-noise ratios and changes in signal shapes due to the presence of highly dispersive dielectric medium in the neuron-microelectrode cleft. This has made it difficult to correlate the extracellularly recorded signals with the intracellular signals recorded using conventional patch-clamp electrophysiology. For bringing about an improvement in the signal-to-noise ratio of the signals recorded on the extracellular microelectrodes and to explore strategies for engineering the neuron-electrode interface there exists a need to model, simulate and characterize the cell-sensor interface to better understand the mechanism of signal transduction across the interface. Efforts to date for modeling the neuron-electrode interface have primarily focused on the use of point or area contact linear equivalent circuit models for a description of the interface with an assumption of passive linearity for the dynamics of the interfacial medium in the cell-electrode cleft. In this dissertation, results are presented from a nonlinear dynamic characterization of the neuroelectronic junction based on Volterra-Wiener modeling which showed that the process of signal transduction at the interface may have nonlinear contributions from the interfacial medium. An optimization based study of linear equivalent circuit models for representing signals recorded at the neuron-electrode interface subsequently proved conclusively that the process of signal transduction across the interface is indeed nonlinear. Following this a theoretical framework for the extraction of the complex nonlinear material parameters of the interfacial medium like the dielectric permittivity, conductivity and diffusivity tensors based on dynamic nonlinear Volterra-Wiener modeling was developed. Within this framework, the use of Gaussian bandlimited white noise for nonlinear impedance spectroscopy was shown to offer considerable advantages over the use of sinusoidal inputs for nonlinear harmonic analysis currently employed in impedance characterization of nonlinear electrochemical systems. Signal transduction at the neuron-microelectrode interface is mediated by the interfacial medium confined to a thin cleft with thickness on the scale of 20-110 nm giving rise to Knudsen numbers (ratio of mean free path to characteristic system length) in the range of 0.015 and 0.003 for ionic electrodiffusion. At these Knudsen numbers, the continuum assumptions made in the use of Poisson-Nernst-Planck system of equations for modeling ionic electrodiffusion are not valid. Therefore, a lattice Boltzmann method (LBM) based multiphysics solver suitable for modeling ionic electrodiffusion at the mesoscale neuron-microelectrode interface was developed. Additionally, a molecular speed dependent relaxation time was proposed for use in the lattice Boltzmann equation. Such a relaxation time holds promise for enhancing the numerical stability of lattice Boltzmann algorithms as it helped recover a physically correct description of microscopic phenomena related to particle collisions governed by their local density on the lattice. Next, using this multiphysics solver simulations were carried out for the charge relaxation dynamics of an electrolytic nanocapacitor with the intention of ultimately employing it for a simulation of the capacitive coupling between the neuron and the planar microelectrode on a microelectrode array (MEA). Simulations of the charge relaxation dynamics for a step potential applied at t = 0 to the capacitor electrodes were carried out for varying conditions of electric double layer (EDL) overlap, solvent viscosity, electrode spacing and ratio of cation to anion diffusivity. For a large EDL overlap, an anomalous plasma-like collective behavior of oscillating ions at a frequency much lower than the plasma frequency of the electrolyte was observed and as such it appears to be purely an effect of nanoscale confinement. Results from these simulations are then discussed in the context of the dynamics of the interfacial medium in the neuron-microelectrode cleft. In conclusion, a synergistic approach to engineering the neuron-microelectrode interface is outlined through a use of the nonlinear dynamic modeling, simulation and characterization tools developed as part of this dissertation research.
Ph.D.
Doctorate
Physics
Sciences
Physics

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Martin, Isabel [Verfasser]. "Electron induced chemical reactions at different states of aggregation / vorgelegt von Isabel Martin". 2007. http://d-nb.info/98892420X/34.

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Książki na temat "Electric field-induced chemical reaction"

Bernstein, Elliot R., red. Chemical Reactions in Clusters. Oxford University Press, 1996. http://dx.doi.org/10.1093/oso/9780195090048.001.0001.

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This book covers important new developments of the last five years in the area of cluster chemistry, presenting an excellent view of the successes and shortcomings of both current state-of-the-art theory and experiment. Each chapter, contributed by a leading expert, places heavy emphasis on theory without which the detailed analysis of the spectroscopic and kinetic results would be compromised. The cluster reactions reviewed in this work include electron and proton transfer reactions, hot atom reactions, vibrational predissociation, radical reactions, and ionic reactions. Some of the theories applied throughout the text are product state distribution determinations, state-to-state dynamical information, and access to the transition stage of the reaction. The discussions serve as a benchmark of how far the field has come since the mid 1980's and will be a good update for students and researchers interested in this area of physical chemistry.

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Raff, Lionel, Ranga Komanduri, Martin Hagan i Satish Bukkapatnam. Neural Networks in Chemical Reaction Dynamics. Oxford University Press, 2012. http://dx.doi.org/10.1093/oso/9780199765652.001.0001.

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This monograph presents recent advances in neural network (NN) approaches and applications to chemical reaction dynamics. Topics covered include: (i) the development of ab initio potential-energy surfaces (PES) for complex multichannel systems using modified novelty sampling and feedforward NNs; (ii) methods for sampling the configuration space of critical importance, such as trajectory and novelty sampling methods and gradient fitting methods; (iii) parametrization of interatomic potential functions using a genetic algorithm accelerated with a NN; (iv) parametrization of analytic interatomic potential functions using NNs; (v) self-starting methods for obtaining analytic PES from ab inito electronic structure calculations using direct dynamics; (vi) development of a novel method, namely, combined function derivative approximation (CFDA) for simultaneous fitting of a PES and its corresponding force fields using feedforward neural networks; (vii) development of generalized PES using many-body expansions, NNs, and moiety energy approximations; (viii) NN methods for data analysis, reaction probabilities, and statistical error reduction in chemical reaction dynamics; (ix) accurate prediction of higher-level electronic structure energies (e.g. MP4 or higher) for large databases using NNs, lower-level (Hartree-Fock) energies, and small subsets of the higher-energy database; and finally (x) illustrative examples of NN applications to chemical reaction dynamics of increasing complexity starting from simple near equilibrium structures (vibrational state studies) to more complex non-adiabatic reactions. The monograph is prepared by an interdisciplinary group of researchers working as a team for nearly two decades at Oklahoma State University, Stillwater, OK with expertise in gas phase reaction dynamics; neural networks; various aspects of MD and Monte Carlo (MC) simulations of nanometric cutting, tribology, and material properties at nanoscale; scaling laws from atomistic to continuum; and neural networks applications to chemical reaction dynamics. It is anticipated that this emerging field of NN in chemical reaction dynamics will play an increasingly important role in MD, MC, and quantum mechanical studies in the years to come.

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Fox, Raymond. The Use of Self. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780190616144.001.0001.

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Części książek na temat "Electric field-induced chemical reaction"

Persoons, A., i L. Hellemans. "The Dynamics of Electric Field Effects in Low Polar Solutions: The Field Modulation Method". W Advances in Chemical Reaction Dynamics, 483–502. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-4734-4_31.

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Hellemans, L., i A. Persoons. "High Electric Field Perturbation and Relaxation of Dipole Equilibria. A Hazardous Undertaking?" W Advances in Chemical Reaction Dynamics, 503–23. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-4734-4_32.

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Sebastian, Anupama, S. V. Amrutha, Shreyas Punacha i T. K. Shajahan. "Dynamics of Chemical Excitation Waves Subjected to Subthreshold Electric Field in a Mathematical Model of the Belousov-Zhabotinsky Reaction". W Nonlinear Dynamics and Applications, 1241–49. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-99792-2_105.

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Wada, Shin-ichi, i Kenichiro Tanaka. "Chemical Reactions Induced by Core Electron Excitations". W Fundamentals of Mass Spectrometry, 61–79. New York, NY: Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-7233-9_4.

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Gosztola, D., H. Yamada i M. R. Wasielewski. "Picosecond Laser-Induced Electric-Field Modulation of Carotenoid Absorption Bands". W Springer Series in Chemical Physics, 458–59. Berlin, Heidelberg: Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/978-3-642-85176-6_175.

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Kumar, Sonu, Lang Qin i Liang-Shih Fan. "External Electric Field Induced Reaction Chemistry: A Review and Perspectives". W ACS Symposium Series, 207–27. Washington, DC: American Chemical Society, 2020. http://dx.doi.org/10.1021/bk-2020-1364.ch008.

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Fujii, Takashi, Kiyohiro Sugiyama, Alexei Zhidkov, Megumu Miki, Eiki Hotta i Koshichi Nemoto. "Interaction of Femtosecond-Laser-Induced Filament Plasma with External Electric Field for the Application to Electric Field Measurement". W Springer Series in Chemical Physics, 195–213. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-06731-5_9.

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Taniguchi, Tomohiro, Toru Torii i Toshiro Higuchi. "Micro Capsule Based Chemical Reactor Using AC Electric Field". W Micro Total Analysis Systems 2001, 189–90. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-010-1015-3_82.

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Tachiya, M. "Effect of an External Electric Field on the Rate of Diffusion-Controlled Reactions". W Chemical Reactivity in Liquids, 371–78. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-1023-5_31.

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Prud'Homme, Roger. "Interaction Between Metal and Plasma with an Electrical Field (Langmuir Probe)". W Flows and Chemical Reactions in an Electromagnetic Field, 131–39. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2014. http://dx.doi.org/10.1002/9781119054153.ch7.

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Streszczenia konferencji na temat "Electric field-induced chemical reaction"

Luque, Jorge, Masayuki Tamura, Joel E. Harrington, Gregory P. Smith, David R. Crosley i Jay B. Jeffries. "NO Laser-Induced Fluorescence as a Flame Thermometer". W Laser Applications to Chemical and Environmental Analysis. Washington, D.C.: Optica Publishing Group, 1996. http://dx.doi.org/10.1364/lacea.1996.lthd.5.

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Measurement of the temperature field is crucial to understanding combustion in practical devices. Imaging of laser-induced fluorescence (LIF) from NO molecules seeded into the flow is an attractive method to determine the temperature field.1 If the seeded NO does not react or become diluted in the flow, accurate temperature measurements can be made from single line excitation with careful consideration of energy transfer and quenching collisions, overlap of laser and transition bandwidth, and detector bandwidth.2 However, NO reacts in the flame front of hydrocarbon flames via reburning phenomena. We investigate the accuracy of LIF measurements of gas temperature using NO seeded into a premixed, laminar, low-pressure methane/air flame. The NO LIF temperature measurements are compared with temperatures determined from rotational distributions measured with LIF using OH as a function of height above the burner. Using the OH temperature profile, the chemical composition of the flame is predicted from a model of the combustion chemistry. This model predicts the amount of NO as a function of reaction time (height above the burner) including reburning in the flame front, the dilution from the combustion products, and the axial transport. The predicted major species concentrations are used to calculate the rate for NO(A) collisional quenching which are compared to measured quenching rates. In the flame front CH temperature measurements using LIF from A-X and B-X electronic transitions are compared to the OH results.

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Gottscho, Richard A. "Laser Diagnostics of Radio Frequency Discharges". W Lasers in Material Diagnostics. Washington, D.C.: Optica Publishing Group, 1987. http://dx.doi.org/10.1364/lmd.1987.we1.

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Recent applications of laser spectroscopy to the study of plasma and plasma-surface processes are reviewed. Using laser-induced fluorescence and optogalvanic spectroscopy, measurements of concentration gradients, reaction probabilities, electric fields, and process end-points have helped to elucidate plasma-chemical mechanisms.

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Gorman, Brandon T., Nathan G. Johnson, James E. Miller i Ellen B. Stechel. "Thermodynamic Investigation of Concentrating Solar Power With Thermochemical Storage". W ASME 2015 9th International Conference on Energy Sustainability collocated with the ASME 2015 Power Conference, the ASME 2015 13th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2015 Nuclear Forum. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/es2015-49810.

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Concentrating solar power systems coupled to energy storage schemes, e.g. storage of sensible energy in a heat transfer fluid, are attractive options to reduce the transient effects of clouding on solar power output and to provide power after sunset and before sunrise. Common heat transfer fluids used to capture heat in a solar receiver include steam, oil, molten salt, and air. These high temperature fluids can be stored so that electric power can be produced on demand, limited primarily by the size of the capacity and the energy density of the storage mechanism. Phase changing fluids can increase the amount of stored energy relative to non-phase changing fluids due to the heat of vaporization or the heat of fusion. Reversible chemical reactions can also store heat; an endothermic reaction captures the heat, the chemical products are stored, and an exothermic reaction later releases the heat and returns the chemical compound to its initial state. Ongoing research is investigating the scientific and commercial potential of such reaction cycles with, for example, reduction (endothermic) and re-oxidation (exothermic) of metal oxide particles. This study includes thermodynamic analyses and considerations for component sizing of concentrating solar power towers with redox active metal oxide based thermochemical storage to reach target electrical output capacities of 0.1 MW to 100 MW. System-wide analyses here use one-dimensional energy and mass balances for the solar field, solar receiver reduction reactor, hot reduced particle storage, re-oxidizer reactor, power block, cold particle storage, and other components pertinent to the design. This work is part of a US Department of Energy (DOE) SunShot project entitled High Performance Reduction Oxidation of Metal Oxides for Thermochemical Energy Storage (PROMOTES).

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Blume, Steffen O. P., Michael J. Schertzer, Ridha Ben Mrad i Pierre E. Sullivan. "Analytical Models to Determine the Electric Field Characteristics of a Multi-Electrode Impedimetric Immunosensor in a Digital Microfluidic Device". W ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-37571.

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The level of integration of digital microfluidics is continually increasing to include the system path from fluid manipulation and transport, on to reagent preparation, and finally reaction detection. Digital microfluidics therefore has the capability to encompass all steps of common biochemical protocols. Reported here is a set of analytical models for the design of a coplanar interdigitated multi-electrode array to be used as an impedimetric immunosensor in a digital microfluidic device for on-chip chemical reaction detection. The models are based on conformal mapping techniques, and are compared to results obtained from finite element analysis to discuss limitations of the model. The analytical models are feasible and inexpensive surrogates for numerical simulation methods.

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Bollinger, L. D., i C. B. Zarowin. "Control of Plasma Etch Rates, Selectivity and Anisotropy with Plasma Parameters". W Optical Fabrication and Testing. Washington, D.C.: Optica Publishing Group, 1987. http://dx.doi.org/10.1364/oft.1987.pdp1.

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We discuss the experimental verification of relations derived earlier (1) between observable plasma etch rate, selectivity and anisotropy and reactor parameters for a variety of etch gases. Since the hetergeneous etch reaction is a superposition of neutral and ionic components, it can be shown that such etch chemistry exhibits enhancement and is made anisotropic by the energy transport of ions to the etch surface only when the process is ion dominated. The ion energy transport is controlled by the plasma sheath electric field-electrode area/gas pressure-collision cross section ratio, E.A./pQ, similarly controlling chemical anisotropy for ion dominated etch reactions. Under such circumstances, we show that many etch gases can yield identical ion transport, etch rate and anisotropy for a given rf current, gas pressure, ion-neutral collision cross section & electrode area, Irf/pQA.

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Jomeh, Sina, i Mina Hoorfar. "Study of the Effect of Electrophoresis on Transport of Biomolecules in Microreactors". W ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2011. http://dx.doi.org/10.1115/icnmm2011-58165.

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The effect of electrophoresis (i.e., applying uniform electric field to use the natural charge of particles) on the transport of a sample (like biomolecules) in active microreactors is numerically investigated. Navier-Stokes equations are solved along with the equations of electrostatics, species mass transport in the buffer and chemical reaction kinetics at reactive surfaces. Unlike previous studies, in which the effect of the charge of the sample bulk on the electric field has been neglected (i.e., the assumption of electroneutrality), here space charge density is assumed to be nonzero. As a result, the governing equations become fully coupled. The efficiency of the microreactor device is analyzed for two different geometries commonly used in biomolecule separation (i.e., open channel and microcylinders). It is shown that the electroneutrality assumption can drastically influence the final adsorbed concentration depending on the device configuration. Average adsorbed surface concentration is compared for each case as a measure of the performance of the device. The plots depicting the influence of the electric field and nonzero space charge density on the bulk concentration profile and the velocity field are also presented and discussed.

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Ben-Nun, M., T. J. Martínez, P. M. Weber i Kent R. Wilson. "Ultrafast X-Ray Diffraction: Theory". W Applications of High Field and Short Wavelength Sources. Washington, D.C.: Optica Publishing Group, 1997. http://dx.doi.org/10.1364/hfsw.1997.thd3.

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Ever since their discovery by Röntgen (more than 100 years ago), x-rays have made the unseen visible. In particular, much of our experimental knowledge about the structure and electronic densities of atoms and molecules is due to x-ray and electron diffraction measurements. X-ray and electron diffraction have been used to measure the structures of almost all small molecules and x-ray diffraction has been the basis (along with nmr) of most of our structural knowledge about biomolecules. Recent advances in the production of ultrashort x-ray and electron pulses1-3 suggest that diffraction (and absorption) techniques may be used to observe evolving, non-equilibrium structures of systems that are undergoing chemical (or biochemical) reactions or physical changes such as a phase transition or annealing. In such an ultrafast diffraction (or absorption) experiment, an ultrashort optical pulse can be used to initiate a chemical reaction and a second delayed x-ray (or electron pulse) can interrogate the reacting system. By varying the time delay between the two pulses, the motions of atoms during a chemical reaction may be reconstructed.4-6 In addition to watching the nuclear motion, at least in principle, x-ray diffraction could be used to follow the dynamics of the electron density involved in chemical bonding and electron flow, and x-ray absorption in the form of chemical shifts of atomic absorption edges could be used to follow the charge or oxidation state of chosen types of atoms. Hence, time resolved x-ray absorption and diffraction may serve as direct ways to watch the evolution of chemical reactions en route from reactants to products, to observe the microscopic processes by which biomolecules perform their tasks and to observe ultrafast process in solid state materials.

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Glownia, J. H., J. A. Misewich i P. P. Sorokin. "Femtosecond Transition-State Absorption Spectroscopy of Bi Atoms Produced by Photodissociation of Gaseous Bi2 Molecules". W International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/up.1990.tub4.

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Spectroscopic observation in real time of the "transition states" of a chemical reaction has recently become possible with advances in ultrafast laser technology. A.H. Zewail et al. have con ducted femtosecond transition-state spectroscopy (FTS) experiments’ on several gas-phase photodissociation reactions. In these FTS experiments, a femtosecond UV pump pulse first excites a molecule to a repulsive electronic state. A tunable femtosecond probe pulse, delayed by a variable time from the pump pulse, then detects one of the photofragments via laser induced fluorescence (LIF) or multiphoton ionization. Spectral changes that arc observed in the (LIF) excitation spectrum at small pump-probe separations thus provide information about variations in the separation between the potential curves involved in the probe transition, occurring as the interatomic spacing is varied, with the photofragment still in the force field of the remaining parts of the molecule, i.e., with the whole photodissociating complex still in the process of passing through a continuous sequence of "transition states".

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Ghasemi, E., Soheil Soleimanikutanaei i Cheng-Xian Lin. "Control of Turbulent Combustion Flow Inside a Gas Turbine Combustion Chamber Using Plasma Actuators". W ASME 2015 Power Conference collocated with the ASME 2015 9th International Conference on Energy Sustainability, the ASME 2015 13th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2015 Nuclear Forum. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/power2015-49499.

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In this paper, effects of a standard plasma actuator on non-premixed turbulent reacting flows in a unique gas turbine combustion chamber have been studied numerically. The computational simulation is conducted by employing the Reynolds Averaged Navier-Stokes (RANS) approach. Chemical reaction kinetics has been modeled using the eddy dissipation concept (EDC) model. The numerical simulation has been carried out by Finite Element Methods. High voltage potential between two copper electrodes separated by a dielectric material has been applied which leads to the generation of plasma and an electric field, which creates a body force. It was found that by orienting the plasma force in the desired direction, combustion rate can be accelerated or controlled. The numerical results have been presented through velocity, temperature, and species concentration profiles under different combustion conditions.

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Bozso, Ferenc. "Electron and Photon-Beam Induced Thin-Film Growth". W The Microphysics of Surfaces: Beam-Induced Processes. Washington, D.C.: Optica Publishing Group, 1991. http://dx.doi.org/10.1364/msbip.1991.ma1.

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The small dimensions of novel electronic and optoelectronic device structures and their abruptly and unconventionally changing material compositions require high levels of spatial and kinetic control of the surface chemical reactions which are involved in the materials' growth or modification. These requirements exclude high temperature processes based on thermally activated chemical reactions. Directed energetic beams (electrons, photons, ions), however, can induce reactions at low temperatures, as well as provide for spatial and kinetic control in microfabrication processes. Electrons and photons of sufficient energy can cause fragmentation and desorption of adsorbed molecules or fragments of them, by inducing electronic excitations to dissociative states1. The surface species after such excitations are mostly of highly reactive radical character, which readily react with the substrate and with other radical or molecular species in the adsorbed layer. The formation of such reactive surface species in a controlled way can provides a basis for non-thermal selective area film growth.

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Raporty organizacyjne na temat "Electric field-induced chemical reaction"

Akinleye, Taiwo, Idil Deniz Akin, Amanda Hohner, Indranil Chowdhury, Richards Watts, Xianming Shi, Brendan Dutmer, James Mueller i Will Moody. Evaluation of Electrochemical Treatment for Removal of Arsenic and Manganese from Field Soil. Illinois Center for Transportation, czerwiec 2021. http://dx.doi.org/10.36501/0197-9191/21-019.

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Soils containing inorganic compounds are frequently encountered by transportation agencies during construction within the right-of-way, and they pose a threat to human health and the environment. As a result, construction activities may experience project delays and increased costs associated with management of inorganic compounds containing soils required to meet environmental regulations. Recalcitrance of metal-contaminated soils toward conventional treatment technologies is exacerbated in clay or organic content-rich fine-grained soils with low permeability and high sorption capacity because of increased treatment complexity, cost, and duration. The objective of this study was to develop an accelerated in situ electrochemical treatment approach to extract inorganic compounds from fine-grained soils, with the treatment time comparable to excavation and off-site disposal. Three reactor experiments were conducted on samples collected from two borehole locations from a field site in Illinois that contained arsenic (As)(~7.4 mg/kg) and manganese (Mn)(~700 mg/kg). A combination of hydrogen peroxide (H2O2) and/or citrate buffer solution was used to treat the soils. A low-intensity electrical field was applied to soil samples using a bench-scale reactor that resembles field-scale in situ electrochemical systems. For the treatment using 10% H2O2 and citrate buffer solution, average removal of 23% and 8% were achieved for Mn and As, respectively. With 4% H2O2 and citrate buffer, 39% and 24% removal were achieved for Mn and As; while using only citrate buffer as the electrolyte, 49% and 9% removal were achieved for Mn and As, respectively. All chemical regimes adopted in this study reduced the inorganic compound concentrations to below the maximum allowable concentration for Illinois as specified by the Illinois Environmental Protection Agency. The results from this work indicate that electrochemical systems that leverage low concentrations of hydrogen peroxide and citrate buffer can be effective for remediating soils containing manganese and arsenic.

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Banin, Amos, Joseph Stucki i Joel Kostka. Redox Processes in Soils Irrigated with Reclaimed Sewage Effluents: Field Cycles and Basic Mechanism. United States Department of Agriculture, lipiec 2004. http://dx.doi.org/10.32747/2004.7695870.bard.

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The overall objectives of the project were: (a) To measure and study in situ the effect of irrigation with reclaimed sewage effluents on redox processes and related chemical dynamics in soil profiles of agricultural fields. (b) To study under controlled conditions the kinetics and equilibrium states of selected processes that affect redox conditions in field soils or that are effected by them. Specifically, these include the effects on heavy metals sorption and desorption, and the effect on pesticide degradation. On the basis of the initial results from the field study, increased effort was devoted to clarifying and quantifying the effects of plants and water regime on the soil's redox potential while the study of heavy metals sorption was limited. The use of reclaimed sewage effluents as agricultural irrigation water is increasing at a significant rate. The relatively high levels of suspended and, especially, dissolved organic matter and nitrogen in effluents may affect the redox regime in field soils irrigated with them. In turn, the changes in redox regime may affect, among other parameters, the organic matter and nitrogen dynamics of the root zone and trace organic decomposition processes. Detailed data of the redox potential regime in field plots is lacking, and the detailed mechanisms of its control are obscure and not quantified. The study established the feasibility of long-term, non-disturbing monitoring of redox potential regime in field soils. This may enable to manage soil redox under conditions of continued inputs of wastewater. The importance of controlling the degree of wastewater treatment, particularly of adding ultrafiltration steps and/or tertiary treatment, may be assessed based on these and similar results. Low redox potential was measured in a field site (Site A, KibutzGivat Brenner), that has been irrigated with effluents for 30 years and was used for 15 years for continuous commercial sod production. A permanently reduced horizon (Time weighted averaged pe= 0.33±3.0) was found in this site at the 15 cm depth throughout the measurement period of 10 months. A drastic cultivation intervention, involving prolonged drying and deep plowing operations may be required to reclaim such soils. Site B, characterized by a loamy texture, irrigated with tap water for about 20 years was oxidized (Time weighted average pe=8.1±1.0) throughout the measurement period. Iron in the solid phases of the Givat Brenner soils is chemically-reduced by irrigation. Reduced Fe in these soils causes a change in reactivity toward the pesticide oxamyl, which has been determined to be both cytotoxic and genotoxic to mammalian cells. Reaction of oxamyl with reduced-Fe clay minerals dramatically decreases its cytotoxicity and genotoxicity to mammalian cells. Some other pesticides are affected in the same manner, whereas others are affected in the opposite direction (become more cyto- and genotoxic). Iron-reducing bacteria (FeRB) are abundant in the Givat Brenner soils. FeRB are capable of coupling the oxidation of small molecular weight carbon compounds (fermentation products) to the respiration of iron under anoxic conditions, such as those that occur under flooded soil conditions. FeRB from these soils utilize a variety of Fe forms, including Fe-containing clay minerals, as the sole electron acceptor. Daily cycles of the soil redox potential were discovered and documented in controlled-conditions lysimeter experiments. In the oxic range (pe=12-8) soil redox potential cycling is attributed to the effect of the daily temperature cycle on the equilibrium constant of the oxygenation reaction of H⁺ to form H₂O, and is observed under both effluent and freshwater irrigation. The presence of plants affects considerably the redox potential regime of soils. Redox potential cycling coupled to the irrigation cycles is observed when the soil becomes anoxic and the redox potential is controlled by the Fe(III)/Fe(II) redox couple. This is particularly seen when plants are grown. Re-oxidation of the soil after soil drying at the end of an irrigation cycle is affected to some degree by the water quality. Surprisingly, the results suggest that under certain conditions recovery is less pronounced in the freshwater irrigated soils.

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