Artykuły w czasopismach: „Electric field-induced chemical reaction”

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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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Szydło, Zbigniew A. "Chemical Electricity". Chemistry-Didactics-Ecology-Metrology 26, nr 1-2 (1.12.2021): 5–29. http://dx.doi.org/10.2478/cdem-2021-0001.

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Abstract In 1800 Alessandro Volta published the results of several years’ work on the phenomenon of electric shocks which he experienced from physical contact with the terminals of his newly developed battery. His work was prompted by Luigi Galvani's explanation of involuntary muscle spasms in frog's legs, which he induced and attributed to animal electricity. Volta's paper opened the floodgates for research in the new field of electrochemistry which has resulted in today's worldwide electric battery industry. This essay explains the sequence of natural events and their explanations which led to the publication of Volta's paper, and gives an overview of the scientific research resulting from Volta's work. This research includes attempts to improve batteries, and the development of ideas which led to a better understanding of matter and the way it interacts with energy. Practical details for the teaching of several important chemical concepts are listed in the appendix. The experiments are related to a reaction which has been known for many centuries - that between iron and copper sulphate solution.

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Sharma, M., P. Kumar, А. В. Иржак, S. Kumar, R. Pratap, С. В. фон Гратовски, В. Г. Шавров i В. В. Коледов. "Плавление и электромиграция в тонких пленках хрома". Физика твердого тела 62, nr 6 (2020): 880. http://dx.doi.org/10.21883/ftt.2020.06.49342.23m.

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Abstract Chromium films with a thickness of 10–40 nm deposited onto silicon substrates by magnetron sputtering are subjected to the action of electric current induced by the tip of an atomic force microscope (AFM) cantilever in air under regular environmental conditions. The melting process at the nanoscale, electric field-induced migration of material, and the chemical reaction of chromium oxidation that occur in melt craters formed around the region affected by the current are investigated using optical and scanning electron microscopies, AFM, and Raman spectroscopy. The flow of melted material induced by electric current is accompanied by the formation and motion of an array of spherical nanoparticles in the melt crater along its periphery. We propose that the formation of nanodrop array at relatively low current densities can be explained by the chromium oxidation reaction and the surface tension of melted material on the silicon substrate.

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Pennino, Donald J., i Edmund R. Malinowski. "Reaction field of an oscillating electric dipole and solvent chemical shift". Journal of the Chemical Society, Faraday Transactions 2 83, nr 6 (1987): 939. http://dx.doi.org/10.1039/f29878300939.

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Hiraki, Yasutaka. "Effects of ion–neutral chemical reactions on dynamics of lightning-induced electric field". Plasma Sources Science and Technology 18, nr 3 (15.07.2009): 034020. http://dx.doi.org/10.1088/0963-0252/18/3/034020.

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Quintans, C. S., Denis Andrienko, Katrin F. Domke, Daniel Aravena, Sangho Koo, Ismael Díez-Pérez i Albert C. Aragonès. "Tuning Single-Molecule Conductance by Controlled Electric Field-Induced trans-to-cis Isomerisation". Applied Sciences 11, nr 8 (7.04.2021): 3317. http://dx.doi.org/10.3390/app11083317.

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External electric fields (EEFs) have proven to be very efficient in catalysing chemical reactions, even those inaccessible via wet-chemical synthesis. At the single-molecule level, oriented EEFs have been successfully used to promote in situ single-molecule reactions in the absence of chemical catalysts. Here, we elucidate the effect of an EEFs on the structure and conductance of a molecular junction. Employing scanning tunnelling microscopy break junction (STM-BJ) experiments, we form and electrically characterize single-molecule junctions of two tetramethyl carotene isomers. Two discrete conductance signatures show up more prominently at low and high applied voltages which are univocally ascribed to the trans and cis isomers of the carotenoid, respectively. The difference in conductance between both cis-/trans- isomers is in concordance with previous predictions considering π-quantum interference due to the presence of a single gauche defect in the trans isomer. Electronic structure calculations suggest that the electric field polarizes the molecule and mixes the excited states. The mixed states have a (spectroscopically) allowed transition and, therefore, can both promote the cis-isomerization of the molecule and participate in electron transport. Our work opens new routes for the in situ control of isomerisation reactions in single-molecule contacts.

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Aardahl, Christopher L., John F. Widmann i E. James Davis. "Raman Analysis of Chemical Reactions Resulting from the Collision of Micrometer-Sized Particles". Applied Spectroscopy 52, nr 1 (styczeń 1998): 47–53. http://dx.doi.org/10.1366/0003702981942627.

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The chemical reaction between two micrometer-sized particles has been studied with the use of Raman spectroscopy. Charged particles of Na2CO3 and (NH4)2SO4 were generated with the use of a vibrating orifice aerosol generator fitted with an inductive charging plate. Two particles, one of each substance and of opposite polarity, were held apart by the dc electric field of an electrodynamic balance (EDB) and then brought together by manipulating the dc potential to permit Coloumbic forces to dominate. Raman spectra taken of the particle aggregate show that chemical reaction did not occur when dry particles were combined, but subsequent exposure of the aggregate to water vapor induced a chemical reaction that resulted in the formation of Na2SO4. The Raman data are presented, and the reaction mechanism and products are discussed.

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Goryushkin, V. F., Yu V. Bendre i N. S. Zaitsev. "Activation of reaction with participation of a solid metal by electrostatic charge energy on the metal". Physics and Chemistry of Materials Treatment 3 (2021): 60–68. http://dx.doi.org/10.30791/0015-3214-2021-3-60-68.

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There are quantitative parameters of an electric energy capacitor artificially created in a chemical reactor were measured in this article. One of the components of this capacitor is the studied samples. Moreover, there are qualitative and quantitative relationships between samples and the accumulated electrical energy reserve of a metal (titanium) in the volume of the surface layer. There is penetration depth of the electrostatic charge into the metal from the outside of the system, energy of the electric field in the dielectric (carbon tetrachloride) and the corrosion rate of titanium in carbon tetrachloride determinate the reserve of electrical energy of the metal. In accordance with these equations, it can be argued that an external message due to the electrostatic charge of titanium in the surface layer of electric energy in the amount for 50 J/mol leads to a 2-fold increase in the reaction rate. There’s an analogy was made in the result of exposure to the samples between other non-standard methods of activation of the chemical reactions and the message from outside of the electrostatic charge in this article. According to this, the developed method for increasing the internal energy of the metal in the surface layer is proposed to be called electrostatic activation, and the reactions are called electrostatic-chemical.

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Munir, Z. A. "Modeling and experimental studies on the effect of thermophysical properties on field-activated combustion synthesis reactions". Pure and Applied Chemistry 72, nr 11 (1.01.2000): 2177–86. http://dx.doi.org/10.1351/pac200072112177.

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The influence of thermal and electrical conductivities and relative density on the dynamics of self-sustaining reactions activated by an electric field was investigated by modeling. Under a given field, the variation of the wave velocity and maximum temperature with normalized electrical and thermal conductivities and density exhibited a maximum at an optimum value of each of the three parameters. The results are discussed in terms of a Fourier relationship modified by the Joule heat contribution of the imposed field. A simulation was also made to investigate the configuration of the reaction front in systems that are ignited and sustained by a current. A transition from a volume (uniform) combustion reaction to a wavelike form was found to occur as the sample size is increased. These changes are also attributed to the interrelation between the thermophysical parameters.

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Dwivedi, Itisha, Arup Sarkar, Gopalan Rajaraman i Chandramouli Subramaniam. "Electric-Field-Induced Solid–Gas Interfacial Chemical Reaction in Carbon Nanotube Ensembles: Route toward Ultra-sensitive Gas Detectors". ACS Applied Materials & Interfaces 14, nr 11 (10.03.2022): 13271–79. http://dx.doi.org/10.1021/acsami.1c23670.

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Santiago Neto, Ruy Batista, i Bernhard Lesche. "Electric field assisted hydrogen fluoride etching of silica". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 465, nr 2111 (21.08.2009): 3447–62. http://dx.doi.org/10.1098/rspa.2009.0216.

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The influence of electric fields on the velocity of the chemical reaction 4HF+SiO 2 →SiF 4 +2H 2 O in aqueous solution is investigated experimentally. The field strengths used were high enough to measure nonlinear effects. The results permit a critical analysis of a theoretical model known in literature. The basic idea of dipole orientation changing the rate of the primary step of the chemical reaction can explain the experimental data, but several important details of the original model had to be changed. The primary step involves two hydrogen fluoride (HF) molecules rather than one, and field screening by mobile ions has a significant influence causing nonlinear effects. The fact that field screening plays an important role implies that electric field-assisted HF etching of silica may by used as an instrument for measuring ion concentrations in highly concentrated electrolytes. The data measured may be well described by a theoretical model based on mean field approximations. The results give an insight into the structure of highly concentrated hydrofluoric acid and also permit a critical analysis of applications of the effect in measuring electric fields written in glass samples by electrothermal poling. The effect may also be used for shaping glass surfaces.

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Hosseini, Seyed Hossein, Amir Abbas Kazemi i Seyed Arash Hosseini. "Preparation of Polycarbazole Nanofibers Using an Electric Field and the Investigation of Its Electrical Conductivity". Nanomanufacturing 3, nr 1 (17.03.2023): 113–22. http://dx.doi.org/10.3390/nanomanufacturing3010007.

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In conventional chemical and electrochemical oxidation methods, it is very difficult to control the active centers, and the average prepared polymers are short and wide. The use of an electric field creates the most stable intermediate form of active centers, as well as permitting a longer half-life. Therefore, this increases the physical resistance and electrical conductivity of the polymer. In this paper, polycarbazole nanofibers were prepared using an electric field, reporting on its influences on the polymerization of carbazole. Therefore, its electrical conductivity and some physical properties were investigated. We observed the nanofibers’ shape, increasing electrical conductivity, thermal resistance and a higher molecular weight with the synthesized polycarbazole under an electric field compared to the polymer synthesized in the same conditions in the absence of an electric field. First, we chemically synthesized polycarbazole at different times. Additionally, to find the optimizing conditions, we changed certain parameters, such as the ratio of the obtained molar of initiator to monomer, the oxidant, initiator and solvent, separately, and compared the obtained results. Then, we repeated this reaction in the best conditions and under different electric fields in constant time, allowing us to characterize the shape, mass and conductivity. Next, the polymerization was carried out at the best electric field in different times. Finally, the best time and amount of electric field for polymerization were determined. The electrical conductivity of polycarbazoles was studied with the four-probe method. The conductivity of the films oxidized using FeCl3 (dry) and protonated with p-toluenesulfonic acid (PTSA) at 3 h was higher than 8.9 × 10−4 S/cm under a 12 KV/m electric field. Additionally, the results showed an enhanced thermal resistance to ageing.

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Rana, Puneet, Nisha Shukla, O. Anwar Bég, A. Kadir i Bani Singh. "Unsteady electromagnetic radiative nanofluid stagnation-point flow from a stretching sheet with chemically reactive nanoparticles, Stefan blowing effect and entropy generation". Proceedings of the Institution of Mechanical Engineers, Part N: Journal of Nanomaterials, Nanoengineering and Nanosystems 232, nr 2-3 (czerwiec 2018): 69–82. http://dx.doi.org/10.1177/2397791418782030.

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This article investigates the combined influence of nonlinear radiation, Stefan blowing and chemical reactions on unsteady electro-magneto-hydrodynamic stagnation-point flow of a nanofluid from a horizontal stretching sheet. Both electrical and magnetic body forces are considered. In addition, the effects of velocity slip, thermal slip and mass slip are considered at the boundaries. An analytical method named as homotopy analysis method is applied to solve the non-dimensional system of nonlinear partial differential equations which are obtained by applying similarity transformations on governing equations. The effects of emerging parameters such as Stefan blowing parameter, electric parameter and magnetic parameter on the important physical quantities are presented graphically. In addition, an entropy generation analysis is provided in this article for thermal optimization. The flow is observed to be accelerated both with increasing magnetic field and electrical field. Entropy generation number is markedly enhanced with greater magnetic field, electrical field and Reynolds number, whereas it is reduced with increasing chemical reaction parameter.

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Zeng, Xingming, Sadaf Bashir Khan, Ayyaz Mahmood i Shern-Long Lee. "Nanoscale tailoring of supramolecular crystals via an oriented external electric field". Nanoscale 12, nr 28 (2020): 15072–80. http://dx.doi.org/10.1039/d0nr01946a.

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The oriented external electric field of a scanning tunneling microscope (STM) has recently been adapted for controlling the chemical reaction and supramolecular phase transition at surfaces with molecular precision.

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Matsuda, Kyle, Luigi De Marco, Jun-Ru Li, William G. Tobias, Giacomo Valtolina, Goulven Quéméner i Jun Ye. "Resonant collisional shielding of reactive molecules using electric fields". Science 370, nr 6522 (10.12.2020): 1324–27. http://dx.doi.org/10.1126/science.abe7370.

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Full control of molecular interactions, including reactive losses, would open new frontiers in quantum science. We demonstrate extreme tunability of ultracold chemical reaction rates by inducing resonant dipolar interactions by means of an external electric field. We prepared fermionic potassium-rubidium molecules in their first excited rotational state and observed a modulation of the chemical reaction rate by three orders of magnitude as we tuned the electric field strength by a few percent across resonance. In a quasi–two-dimensional geometry, we accurately determined the contributions from the three dominant angular momentum projections of the collisions. Using the resonant features, we shielded the molecules from loss and suppressed the reaction rate by an order of magnitude below the background value, thereby realizing a long-lived sample of polar molecules in large electric fields.

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Tsong, Tian Yow, Dao-Sheng Liu, Francoise Chauvin i R. Dean Astumian. "Resonance electroconformational coupling: A proposed mechanism for energy and signal transductions by membrane proteins". Bioscience Reports 9, nr 1 (1.02.1989): 13–26. http://dx.doi.org/10.1007/bf01117508.

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Recent experiments show that membrane ATPases are capable of absorbing free energy from an applied oscillating electric field and converting it to chemical bond energy of ATP or chemical potential energy of concentration gradients. Presumably these enzymes would also respond to endogenous transmembrane electric fields of similar intensity and waveform. A mechanism is proposed in which energy coupling is achieved via Coulombic interaction of an electric field and the conformational equilibria of an ATPase. Analysis indicates that only an oscillating or fluctuating electric field can be used by an enzyme to drive a chemical reaction away from equilibrium. In vivo, the stationary transmembrane potential of a cell must be modulated to become “locally” oscillatory if it is to derive energy and signal transduction processes.

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Cassone, Giuseppe, Fabio Pietrucci, Franz Saija, François Guyot i A. Marco Saitta. "One-step electric-field driven methane and formaldehyde synthesis from liquid methanol". Chemical Science 8, nr 3 (2017): 2329–36. http://dx.doi.org/10.1039/c6sc04269d.

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Song, Xiaozong, Shundong Ge, Yanjiang Niu i Dengwei Yan. "Effect of external electric field on ultraviolet-induced nanoparticle colloid jet machining". Nanotechnology 33, nr 21 (4.03.2022): 215302. http://dx.doi.org/10.1088/1361-6528/ac55d0.

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Abstract Electric field enhanced ultraviolet (UV)-induced nanoparticle colloid jet machining is proposed to improve the material removal efficiency of UV-induced nanoparticle colloid jet machining by applying an external electric field. The influences of TiO2 nanoparticle concentration, applied electric field voltage and pH value for the photocatalytic activity of the polishing slurry was investigated by orthogonal experiments. Terephthalic acid (TPA) was used as a fluorescent molecular probe to reflect the relative concentration of hydroxyl radical groups (·OH) in polishing slurry, which directly affects the material removal rate in the UV-induced nanoparticle colloid jet machining process. Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and x-ray photoelectron spectroscopy (XPS) were employed to inspect the interaction variations between the TiO2 nanoparticles and the SiC workpiece surface. The SEM and XPS results exhibit that the external electric field can enhance the adsorption of TiO2 nanoparticles on the SiC workpiece surface, which can create more interfacial reaction active centers in the polishing process. The FT-IR spectra results indicate that TiO2 nanoparticles were chemically bonded to the SiC surface by oxygen-bridging atoms in Ti–O–Si bonds. The results of fixed-point polishing experiment show that due to the enhancement effect of external electric field on the photocatalytic activity of the polishing slurry, the material removal efficiency of electric field enhanced UV-induced nanoparticle colloid jet machining is 15% higher than that of UV-induced nanoparticle colloid jet machining, and is 28% higher than that of pure nanoparticle colloid jet machining. Atomic force microscope micromorphology show that an ultra-smooth SiC workpieces with surface roughness of Rms 0.84 nm (Ra 0.474 nm) has been obtained by electric field enhanced UV-induced nanoparticle colloid jet machining.

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Kharlamov, V. F., A. V. Sedov i S. N. Romashin. "Electron emission from solid surfaces stimulated by electric field and heterogeneous chemical reaction". Technical Physics Letters 30, nr 9 (wrzesień 2004): 753–55. http://dx.doi.org/10.1134/1.1804586.

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Yang, Kai-Yun, Ing-Chi Leu, Kuan-Zong Fung, Min-Hsiung Hon, Ming-Chi Hsu, Yu-Jen Hsiao i Moo-Chin Wang. "Mechanism of the interfacial reaction between cation-deficient La0.56Li0.33TiO3 and metallic lithium at room temperature". Journal of Materials Research 23, nr 7 (lipiec 2008): 1813–25. http://dx.doi.org/10.1557/jmr.2008.0255.

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We used x-ray diffractometry (XRD), x-ray photoelectron spectrometry (XPS), and secondary-ion mass spectrometry (SIMS) to investigate the mechanism of the interfacial room-temperature (RT) chemical reaction between cation-deficient La0.56Li0.33TiO3 solid electrolytes and metallic lithium anodes in all-solid-state lithium batteries. A stoichiometric mixture of La2O3, Li2CO3, and TiO2 powders was calcined at 1250 °C for 8 h to obtain a single perovskite structure of La0.56Li0.33TiO3. When this La0.56Li0.33TiO3 sample and lithium were placed in contact at room temperature for 24 h, the phase of the La0.56Li0.33TiO3 remained unchanged. The XPS results indicate that 12% of the tetravalent Ti4+ ions were converted into trivalent Ti3+ ions. The valence conversion and degree of conversion were limited by the structural rigidity of the host crystal. Our SIMS analysis suggests the existence of a local electric field near the contact surface and indicates that the 6Li+ isotope ions were inserted into the specimen through the effect of this field. The change in the electrical properties of La0.56Li0.33TiO3 supports this mechanism for the interfacial reaction. The ionic conductivities of the grain and total grain boundary decreased and increased, respectively, after the insertion of Li+, and the total electronic conductivity increased as a result of the presence of intervalence electron hopping between mixed Ti3+/Ti4+ states. The mechanism of the lithium-activated RT interfacial reaction is associated with the reduction of Ti4+ transition metal ions from tetravalent to trivalent states and the local-electric-field-induced Li+ insertion into La3+/Li+-site vacancies of La0.56Li0.33TiO3.

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Liu, Xingpeng, Heping Huang, Linsen Yang i Kama Huang. "Degree of Coupling in Microwave-Heating Polar-Molecule Reactions". Molecules 28, nr 3 (31.01.2023): 1364. http://dx.doi.org/10.3390/molecules28031364.

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Microwave-assisted chemical reactions have been widely used, but the overheating effect limits further applications. The aim of this paper is to investigate the coupling degree of the electromagnetic field and thermal field in microwave-heating chemical reactions whose polarization changes as the reactions proceed. First, the entropy-balance equation of microwave-heating polar-molecule reactions is obtained. Then, the coupling degree of the electromagnetic field and the thermal field in microwave-heating polar-molecule reactions is derived, according to the entropy-balance equation. Finally, the effects of reaction processes on the degree of coupling are discussed. When the time scale of the component-concentration variation is much greater than the wave period during the chemical processes, the degree of coupling is sufficiently small, and the electric and thermal fields are considered as weakly coupled. On the other hand, the degree of coupling may change during the reactions. If the absolute value of the coupling degree becomes larger, due to the change in component concentration, this will lead to a transition from weak coupling to strong coupling.

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PENG, Yongkang, Xiaoyue CHEN, Yeqiang DENG, Lei LAN, Haoyu ZHAN, Xuekai PEI, Jiahao CHEN, Yukuan YUAN i Xishan WEN. "Kinetic study of key species and reactions of atmospheric pressure pulsed corona discharge in humid air". Plasma Science and Technology 24, nr 5 (13.04.2022): 055404. http://dx.doi.org/10.1088/2058-6272/ac4693.

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Abstract In this study, we examined the key particles and chemical reactions that substantially influence plasma characteristics. In summarizing the chemical reaction model for the discharge process of N2–O2–H2O(g) mixed gases, 65 particle types and 673 chemical reactions were investigated. On this basis, a global model of atmospheric pressure humid air discharge plasma was developed, with a focus on the variation of charged particles densities and chemical reaction rates with time under the excitation of a 0–200 Td pulsed electric field. Particles with a density greater than 1% of the electron density were classified as key particles. For such particles, the top ranking generation or consumption reactions (i.e. where the sum of their rates was greater than 95% of the total rate of the generation or consumption reactions) were classified as key chemical reactions. On the basis of the key particles and reactions identified, a simplified global model was derived. A comparison of the global model with the simplified global model in terms of the model parameters, particle densities, reaction rates (with time), and calculation efficiencies demonstrated that both models can adequately identify the key particles and chemical reactions reflecting the chemical process of atmospheric pressure discharge plasma in humid air. Thus, by analyzing the key particles and chemical reaction pathways, the charge and substance transfer mechanism of atmospheric pressure pulse discharge plasma in humid air was revealed, and the mechanism underlying water vapor molecules’ influence on atmospheric pressure air discharge was elucidated.

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Chmelíková, R., M. Přibyl, F. Tm??j, P. Hasal i M. Marek. "Effects of an Electric Field on Enzymatic Reaction with Immobilized Enzyme". Chemie Ingenieur Technik 73, nr 6 (czerwiec 2001): 653–54. http://dx.doi.org/10.1002/1522-2640(200106)73:6<653::aid-cite6534444>3.0.co;2-4.

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Dakhnovskii, Yuri. "Nonadiabatic chemical reactions in a strong time‐dependent electric field: An electron transfer reaction in a polar solvent". Journal of Chemical Physics 100, nr 9 (maj 1994): 6492–99. http://dx.doi.org/10.1063/1.467058.

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Umavathi, J. C., J. P. Kumar, R. S. R. Gorla i B. J. Gireesha. "Effect of Electric Field on Dispersion of a Solute in an MHD Flow through a Vertical Channel With and Without Chemical Reaction". International Journal of Applied Mechanics and Engineering 21, nr 3 (1.08.2016): 683–711. http://dx.doi.org/10.1515/ijame-2016-0041.

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Abstract The longitudinal dispersion of a solute between two parallel plates filled with two immiscible electrically conducting fluids is analyzed using Taylor’s model. The fluids in both the regions are incompressible and the transport properties are assumed to be constant. The channel walls are assumed to be electrically insulating. Separate solutions are matched at the interface using suitable matching conditions. The flow is accompanied by an irreversible first-order chemical reaction. The effects of the viscosity ratio, pressure gradient and Hartman number on the effective Taylor dispersion coefficient and volumetric flow rate for an open and short circuit are drawn in the absence and in the presence of chemical reactions. As the Hartman number increases the effective Taylor diffusion coefficient decreases for both open and short circuits. When the magnetic field remains constant, the numerical results show that for homogeneous and heterogeneous reactions, the effective Taylor diffusion coefficient decreases with an increase in the reaction rate constant for both open and short circuits.

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Holmes, Thomas D., Rachael H. Rothman i William B. Zimmerman. "Graph Theory Applied to Plasma Chemical Reaction Engineering". Plasma Chemistry and Plasma Processing 41, nr 2 (19.01.2021): 531–57. http://dx.doi.org/10.1007/s11090-021-10152-z.

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AbstractThis work explores the following applications of graph theory to plasma chemical reaction engineering: assembly of a weighted directional graph with the key addition of reaction nodes, from a published set of reaction data for air; graph visualisation for probing the reaction network for potentially useful or problematic reaction pathways; running Dijkstra’s algorithm between all species nodes; further analysis of the graph for useful engineering information such as which conditions, reactions, or species could be enhanced or supressed to favour particular outcomes, e.g. targeted chemical formation. The use of reaction-nodes combined with derived parameters allowed large amounts of key information regarding the plasma chemical reaction network to be assessed simultaneously using a leading open source graph visualisation software (Gephi). A connectivity matrix of Dijkstra’s algorithm between each two species gave a measure of the relative potential of species to be created and destroyed under specific conditions. Further investigation into using the graph for key reaction engineering information led to the development of a graph analysis algorithm to quantify demand for conditions for targeted chemical formation: Optimal Condition Approaching via Reaction-In-Network Analysis (OCARINA). Predictions given by running OCARINA display significant similarities to a well-known electric field strength regime for optimal ozone production in air. Time dependent 0D simulations also showed preferential formation for O· and O3 using the respective conditions generated by the algorithm. These applications of graph theory to plasma chemical reaction engineering show potential in identifying promising simulations and experiments to devote resources.

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Cassone, Giuseppe, Adriano Sofia, Jiri Sponer, A. Marco Saitta i Franz Saija. "Ab Initio Molecular Dynamics Study of Methanol-Water Mixtures under External Electric Fields". Molecules 25, nr 15 (24.07.2020): 3371. http://dx.doi.org/10.3390/molecules25153371.

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Intense electric fields applied on H-bonded systems are able to induce molecular dissociations, proton transfers, and complex chemical reactions. Nevertheless, the effects induced in heterogeneous molecular systems such as methanol-water mixtures are still elusive. Here we report on a series of state-of-the-art ab initio molecular dynamics simulations of liquid methanol-water mixtures at different molar ratios exposed to static electric fields. If, on the one hand, the presence of water increases the proton conductivity of methanol-water mixtures, on the other, it hinders the typical enhancement of the chemical reactivity induced by electric fields. In particular, a sudden increase of the protonic conductivity is recorded when the amount of water exceeds that of methanol in the mixtures, suggesting that important structural changes of the H-bond network occur. By contrast, the field-induced multifaceted chemistry leading to the synthesis of e.g., hydrogen, dimethyl ether, formaldehyde, and methane observed in neat methanol, in 75:25, and equimolar methanol-water mixtures, completely disappears in samples containing an excess of water and in pure water. The presence of water strongly inhibits the chemical reactivity of methanol.

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Huizinga, Menno, Huub A. W. Ragas, Arno H. J. Schrijvers i Jaap Biemond. "Electric reaction field of a molecular octopole and the solvent proton chemical shift of methane". Journal of the Chemical Society, Faraday Transactions 2 83, nr 11 (1987): 2067. http://dx.doi.org/10.1039/f29878302067.

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Baykusheva, Denitsa, Daniel Zindel, Vít Svoboda, Elias Bommeli, Manuel Ochsner, Andres Tehlar i Hans Jakob Wörner. "Real-time probing of chirality during a chemical reaction". Proceedings of the National Academy of Sciences 116, nr 48 (13.11.2019): 23923–29. http://dx.doi.org/10.1073/pnas.1907189116.

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Chiral molecules interact and react differently with other chiral objects, depending on their handedness. Therefore, it is essential to understand and ultimately control the evolution of molecular chirality during chemical reactions. Although highly sophisticated techniques for the controlled synthesis of chiral molecules have been developed, the observation of chirality on the natural femtosecond time scale of a chemical reaction has so far remained out of reach in the gas phase. Here, we demonstrate a general experimental technique, based on high-harmonic generation in tailored laser fields, and apply it to probe the time evolution of molecular chirality during the photodissociation of 2-iodobutane. These measurements show a change in sign and a pronounced increase in the magnitude of the chiral response over the first 100 fs, followed by its decay within less than 500 fs, revealing the photodissociation to achiral products. The observed time evolution is explained in terms of the variation of the electric and magnetic transition-dipole moments between the lowest electronic states of the cation as a function of the reaction coordinate. These results open the path to investigations of the chirality of molecular-reaction pathways, light-induced chirality in chemical processes, and the control of molecular chirality through tailored laser pulses.

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Rezaee, Milad, Mostafa Nasrollahi Gisel i Saman Saffari. "Mathematical Modeling and Sensitivity Analysis on Cadmium Transport in Kaolinite under Direct Current Electric Field". Civil Engineering Journal 3, nr 11 (10.12.2017): 1097. http://dx.doi.org/10.28991/cej-030940.

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Soil pollution is a challenging concern for environmentalists. Different remediation methods have been proposed to remediate polluted soils. Most of the existing methods cannot purify low permeable soils. Electrokinetic remediation (EKR) is an effective method which can remediate fine-grained soils. Understanding the physicochemical phenomena of the EKR is necessary to achieve efficient experimental framework. Therefore, the present study aims to introduce a theoretical and mathematical model for the EKR process. In the present model, different transport phenomena including ion migration, electroosmotic flow, and diffusion were considered. In addition, Chemical reactions such as adsorption/desorption, precipitation/dissolution, water autoionization reaction, and electrolysis reaction were considered. For modeling purpose, a set of partial differential and algebraic equations were used to model the remediation process. The implicit finite difference numerical model showed a good capability of simulating the EKR process. The sensitivity analysis on the retardation and tortuosity factors represented that the retardation factor had a considerable effect on the pH and cadmium concentration profiles. Although tortuosity factor did not have a significant impact on the pH profile, it had a non-negligible effect on the cadmium concentration profile.

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Wan, Ningbo, Jichun Jiang, Fan Hu, Ping Chen, Kaixin Zhu, Dehui Deng, Yuanyuan Xie, Chenxin Wu, Lei Hua i Haiyang Li. "Nonuniform Electric Field-Enhanced In-Source Declustering in High-Pressure Photoionization/Photoionization-Induced Chemical Ionization Mass Spectrometry for Operando Catalytic Reaction Monitoring". Analytical Chemistry 93, nr 4 (7.01.2021): 2207–14. http://dx.doi.org/10.1021/acs.analchem.0c04081.

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Suzuki, S., K. Hamasaki, M. Takahashi, C. Kato i N. Ohnishi. "Numerical analysis of structural change process in millimeter-wave discharge at subcritical intensity". Physics of Plasmas 29, nr 9 (wrzesień 2022): 093507. http://dx.doi.org/10.1063/5.0096363.

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Plasma-front propagation processes of 170 GHz millimeter-wave discharge were investigated under subcritical incident electric field intensity by using a one-dimensional model. The discharge structure was numerically reproduced at more than 0.2 MV/m by introducing the detailed chemical reaction and radiation transport processes into the conventional model. The results revealed that the propagation mechanism of the plasma front in the millimeter-wave discharge changes depending on the incident electric field intensity. At intensities greater than 1.4 MV/m, the plasma front propagated at supersonic speed, while forming a discrete structure, which has intervals of 1/4 wavelength of the millimeter wave. This structure was generated by electron-impact ionization and photoionization processes. At the intermediate intensities, the plasma front propagated continuously rather than discretely because the gas expansion increased the reduced electric field and induced electron-impact ionization. The dominant heating process at the plasma front was fast gas heating. At intensities less than 0.3 MV/m, the plasma front propagated continuously, but the dominant heating process changed to vibrational–translational relaxation. The discharge was maintained by thermal ionization and associative ionization. The simulation results were in good agreement with the past millimeter discharge experiments at this intensity.

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Terzis, Dimitrios, Patrick Hicher i Lyesse Laloui. "Benefits and drawbacks of applied direct currents for soil improvement via carbonate mineralization". E3S Web of Conferences 195 (2020): 05007. http://dx.doi.org/10.1051/e3sconf/202019505007.

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The study presented herein adopts a new vision of the processes involved in carbonate mineralization induced by MICP from an electrochemical and crystal growth perspective. More precisely a specific line of focus refers to the species involved in the bio-chemical reactions and especially their net particle charge. By altering electro-chemical conditions via the application of direct electric currents, we observe distinctive trends related to: (i) overall reaction efficiency; (ii) carbonate mineralization/dissolution and (iii) spatial distribution of precipitates. The study introduces the concept of EA-MICP which stands for Electrically Assisted MICP as a means of improving the efficiency of soil bio-consolidation and overcoming various challenges which were previously reported in conventional MICP-based works. Results reveal both the detrimental and highly beneficial role that electric currents can hold in the complex, reactive and transport processes involved. An interesting finding is the “doped” morphology of calcite crystals, precipitated under electric fields, validated by microstructural observations.

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Shaik, Sason, David Danovich, Jyothish Joy, Zhanfeng Wang i Thijs Stuyver. "Electric-Field Mediated Chemistry: Uncovering and Exploiting the Potential of (Oriented) Electric Fields to Exert Chemical Catalysis and Reaction Control". Journal of the American Chemical Society 142, nr 29 (18.06.2020): 12551–62. http://dx.doi.org/10.1021/jacs.0c05128.

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Tobias, William G., Kyle Matsuda, Jun-Ru Li, Calder Miller, Annette N. Carroll, Thomas Bilitewski, Ana Maria Rey i Jun Ye. "Reactions between layer-resolved molecules mediated by dipolar spin exchange". Science 375, nr 6586 (18.03.2022): 1299–303. http://dx.doi.org/10.1126/science.abn8525.

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Microscopic control over polar molecules with tunable interactions enables the realization of distinct quantum phenomena. Using an electric field gradient, we demonstrated layer-resolved state preparation and imaging of ultracold potassium-rubidium molecules confined to two-dimensional planes in an optical lattice. The rotational coherence was maximized by rotating the electric field relative to the light polarization for state-insensitive trapping. Spatially separated molecules in adjacent layers interact through dipolar spin exchange of rotational angular momentum; by adjusting these interactions, we regulated the local chemical reaction rate. The resonance width of the exchange process vastly exceeded the dipolar interaction energy, an effect attributed to thermal energy. This work realized precise control of interacting molecules, enabling electric field microscopy on subwavelength scales and allowing access to unexplored physics in two-dimensional systems.

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45

Le, Thu Hac Huong, Kazuma Mawatari, Yuriy Pihosh, Tadashi Kawazoe, Takashi Yatsui, Motoichi Ohtsu i Takehiko Kitamori. "Novel sub-100 nm surface chemical modification by optical near-field induced photocatalytic reaction". Microfluidics and Nanofluidics 17, nr 4 (14.02.2014): 751–58. http://dx.doi.org/10.1007/s10404-014-1361-7.

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Adem, Gossaye Aliy. "Analytic Treatment for Electrical MHD Non-Newtonian Fluid Flow over a Stretching Sheet through a Porous Medium". Advances in Mathematical Physics 2020 (28.12.2020): 1–14. http://dx.doi.org/10.1155/2020/8879264.

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In this study, an attempt has been made to investigate the mass and heat transfer effects in a BLF through a porous medium of an electrically conducting viscoelastic fluid subject to a transverse magnetic field in the existence of an external electric field, heat source/sink, and chemical reaction. It has been considered the effects of the electric field, viscous and Joule dissipations, radiation, and internal heat generation/absorption. Closed-form solutions for the boundary layer equations of viscoelastic, second-grade, and Walters’ B ′ fluid models are considered. The method of the solution includes similarity transformation. The converted equations of thermal and mass transport are calculated using the optimal homotopy asymptotic method (OHAM). The solutions of the temperature field for both prescribed surface temperature (PST) and prescribed surface heat flux (PHF) are found. It is vital to remark that the interaction of the magnetic field is found to be counterproductive in enhancing velocity and concentration distribution, whereas the presence of chemical reaction, as well as a porous matrix with moderate values of the magnetic parameter, reduces the temperature and concentration fields at all points of the flow domain.

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47

Nakano, Naoya, Maki Torimoto, Hiroshi Sampei, Reiji Yamashita, Ryota Yamano, Koki Saegusa, Ayaka Motomura i in. "Elucidation of the reaction mechanism on dry reforming of methane in an electric field by in situ DRIFTs". RSC Advances 12, nr 15 (2022): 9036–43. http://dx.doi.org/10.1039/d2ra00402j.

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48

Wang, Jing, Fan Yang, Shuai Wang, Hong Zhong, Zai-kun Wu i Zhan-fang Cao. "Reactivation of nano-Fe3O4/diethanolamine/rGO catalyst by using electric field in Fenton reaction". Journal of the Taiwan Institute of Chemical Engineers 99 (czerwiec 2019): 113–22. http://dx.doi.org/10.1016/j.jtice.2019.03.009.

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Zhu, Zhang, Wang, Zhu, Gao, Zhao, Zhang i Chen. "Controlling the Growth Locations of Ag Nanoparticles at Nanoscale by Shifting LSPR Hotspots". Nanomaterials 9, nr 11 (31.10.2019): 1553. http://dx.doi.org/10.3390/nano9111553.

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Controlling chemical reactions by plasma is expected to be a new method for improving the structural properties of substrates. An Au nanojar array was prepared when Au was deposited onto a 2D polystyrene (PS) array. The site-selective chemical growth of Ag nanoparticle rings was realized around the Au nanojar necks by a local surface plasmon resonance (LSPR)-assisted chemical reaction. The catalytic hotspots in the nanostructure array could be controlled by both etching the nanojars and Au or TiO2 sputtering onto the nanojars, which were confirmed by the growth sites of the Ag nanoparticle in the LSPR-assisted chemical reaction. The structure of the nanojars and the electric field distributions of the growing nanoparticles were simulated and analyzed using Finite-Difference Time-Domain. FDTD simulations showed that the changes in the nanojar shape led to the changed hotspot distributions. At the same time, tracking the hotspot shifts in the process of structural change was also achieved by the observation of Ag growth. Nanoarray structure prepared by LSPR-assisted chemical reaction is one of the hot fields in current research and is also of great significance for the application of Surface-Enhanced Raman Scattering.

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Boricic, Aleksandar, Milos Jovanovic i Branko Boricic. "Unsteady magnetohydrodynamic thermal and diffusion boundary layer from a horizontal circular cylinder". Thermal Science 20, suppl. 5 (2016): 1367–80. http://dx.doi.org/10.2298/tsci16s5367b.

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The unsteady 2-D dynamic, thermal, and diffusion magnetohydrodynamic laminar boundary layer flow over a horizontal cylinder of incompressible and electrical conductivity fluid, in mixed convection in the presence of heat source or sink and chemical reactions. The present magnetic field is homogenous and perpendicular to the body surface. It is assumed that induction of outer magnetic field is a function of longitudinal co-ordinate outer electric field is neglected and magnetic Reynolds number is significantly lower than one, i. e. considered the problem is in approximation without induction. Fluid electrical conductivity is constant. Free stream velocity, temperature, and concentration on the body are functions of longitudinal co-ordinate. The developed governing boundary layer equations and associated boundary conditions are made dimensionless using a suitable similarity transformation and similarity parameters. System of non-dimensionless equations is solved using the implicit finite difference three-diagonal and iteration method. Numerical results are obtained and presented for different Prandtl, Eckart, and Schmidt numbers, and values: magnetic parameter, temperature, and diffusion parameters, buoyancy temperature parameters, thermal parameter, and chemical reaction parameter. Variation of velocity profiles, temperature and diffusion distributions, and many integral and differential characteristics, boundary layer, are evaluated numerically for different values of the magnetic field. Transient effects of velocity, temperature and diffusion are analyzed. A part of obtained results is given in the form of figures and corresponding conclusions.

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