Готові списки джерел за темами / Hydrogen atom transfers

Добірка наукової літератури з теми "Hydrogen atom transfers"

Автор: Grafiati
Опубліковано: 7 липня 2024

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Зміст

  1. Статті в журналах
  2. Дисертації
  3. Книги
  4. Частини книг
  5. Тези доповідей конференцій
  6. Звіти організацій

Статті в журналах з теми "Hydrogen atom transfers":

1

Inagaki, Makoto, Kazuhiko Ninomiya, Akihiro Nambu, Takuto Kudo, Kentaro Terada, Akira Sato, Yoshitaka Kawashima, Dai Tomono, and Atsushi Shinohara. "Chemical effect on muonic atom formation through muon transfer reaction in benzene and cyclohexane samples." Radiochimica Acta 109, no. 4 (February 11, 2021): 319–26. http://dx.doi.org/10.1515/ract-2020-0112.

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Abstract To investigate the chemical effect on the muon capture process through a muon transfer reaction from a muonic hydrogen atom, the formation rate of muonic carbon atoms is measured for benzene and cyclohexane molecules in liquid samples. The muon transfer rate to carbon atoms of the benzene molecule is higher than that to the carbon atoms of the cyclohexane molecule. Such a deviation has never been observed among those molecules for gas samples. This may be because the transfers occur from the excited states of muonic hydrogen atoms in the liquid system, whereas in the gas system, all the transfers occur from the 1s (ground) state of muon hydrogen atoms. The muonic hydrogen atoms in the excited states have a larger radius than those in the 1s state and are therefore considered to be affected by the steric hindrance of the molecular structure. This indicates that the excited states of muonic hydrogen atoms contribute significantly to the chemical effects on the muon transfer reaction.
2

Yao, Chengbo, Tobias Dahmen, Andreas Gansäuer, and Jack Norton. "Anti-Markovnikov alcohols via epoxide hydrogenation through cooperative catalysis." Science 364, no. 6442 (May 23, 2019): 764–67. http://dx.doi.org/10.1126/science.aaw3913.

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The opening of epoxides typically requires electrophilic activation, and subsequent nucleophilic (SN2) attack on the less substituted carbon leads to alcohols with Markovnikov regioselectivity. We describe a cooperative catalysis approach to anti-Markovnikov alcohols by combining titanocene-catalyzed epoxide opening with chromium-catalyzed hydrogen activation and radical reduction. The titanocene enforces the anti-Markovnikov regioselectivity by forming the more highly substituted radical. The chromium catalyst sequentially transfers a hydrogen atom, proton, and electron from molecular hydrogen, avoiding a hydride transfer to the undesired site and resulting in 100% atom economy. Each step of the interconnected catalytic cycles was confirmed separately.
3

Salvitti, Chiara, Federico Pepi, Anna Troiani, Marzio Rosi, and Giulia de Petris. "The Peroxymonocarbonate Anion HCO4− as an Effective Oxidant in the Gas Phase: A Mass Spectrometric and Theoretical Study on the Reaction with SO2." Molecules 28, no. 1 (December 23, 2022): 132. http://dx.doi.org/10.3390/molecules28010132.

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The peroxymonocarbonate anion, HCO4−, the covalent adduct between the carbon dioxide and hydrogen peroxide anion, effectively reacts with SO2 in the gas phase following three oxidative routes. Mass spectrometric and electronic structure calculations show that sulphur dioxide is oxidised through a common intermediate to the hydrogen sulphate anion, sulphur trioxide, and sulphur trioxide anion as primary products through formal HO2−, oxygen atom, and oxygen ion transfers. The hydrogen sulphite anion is also formed as a secondary product from the oxygen atom transfer path. The uncommon nucleophilic behaviour of HCO4− is disclosed by the Lewis acidic properties of SO2, an amphiphilic molecule that forms intermediates with characteristic and diagnostic geometries with peroxymonocarbonate.
4

Arnaut, Luis G., Sebastião J. Formosinho, and Monica Barroso. "Tunnelling in low-temperature hydrogen-atom and proton transfers." Journal of Molecular Structure 786, no. 2-3 (April 2006): 207–14. http://dx.doi.org/10.1016/j.molstruc.2005.10.002.

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5

Isborn, Christine, David A. Hrovat, Weston Thatcher Borden, James M. Mayer, and Barry K. Carpenter. "Factors Controlling the Barriers to Degenerate Hydrogen Atom Transfers." Journal of the American Chemical Society 127, no. 16 (April 2005): 5794–95. http://dx.doi.org/10.1021/ja050024b.

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6

Wu, Yingxi, Hongyan Wang, Yuexia Lin, Simin Gao, and Feng Zhang. "Hydrogen-bonded proton transfer in the hydrated adenine–thymine anion." Canadian Journal of Chemistry 91, no. 10 (October 2013): 992–98. http://dx.doi.org/10.1139/cjc-2013-0162.

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The proton transfer processes of microhydrated adenine–thymine anions are studied using density functional theory with the B3LYP method and DZP++ basis set. The microhydration effects on the geometrical structures, adsorption site, and the proton transfer reaction of the adenine–thymine anion are investigated. The site N10 atom of the adenine moiety has a larger proton affinity than the site O24 atom of thymine, which facilitates the proton H26 transfers from the N25 site of thymine to the N10 site of adenine. Therefore, the first single-proton transfer pathway (SPT1) is found for the all of the monohydrated adenine–thymine anions (AN4T)−·H2O, (AN13T)−·H2O, (ATO24)−·H2O, and (ATO28)−·H2O and tetrahydrated adenine–thymine anions (AT)−·4H2O. The proton H9 at the N7 site of adenine is also found to transfer to the O24 site of thymine for (AN4T)−·H2O and (AN13T)−·H2O in the gas phase. The double-proton transferred pathway is found when one water molecule interacts with the O28 atom of thymine. The reactant structures before the proton transfer are more stable than the product structures, and the structural changes mainly occur in thymine. The reaction energies of the microhydrated adenine–thymine anion in the gas phase and in the aqueous environment predict that the proton transfer process of the microhydrated adenine–thymine anion are more favorable in the gas phase than in aqueous solution.
7

Zheng, Jingjing, Yan Zhao, and Donald G. Truhlar. "Thermochemical Kinetics of Hydrogen-Atom Transfers between Methyl, Methane, Ethynyl, Ethyne, and Hydrogen." Journal of Physical Chemistry A 111, no. 21 (May 2007): 4632–42. http://dx.doi.org/10.1021/jp070252n.

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8

Tommos, Cecilia. "Electron, proton and hydrogen–atom transfers in photosynthetic water oxidation." Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 357, no. 1426 (October 29, 2002): 1383–94. http://dx.doi.org/10.1098/rstb.2002.1135.

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When photosynthetic organisms developed so that they could use water as an electron source to reduce carbon dioxide, the stage was set for efficient proliferation. Algae and plants spread globally and provided the foundation for our atmosphere and for O 2 –based chemistry in biological systems. Light–driven water oxidation is catalysed by photosystem II, the active site of which contains a redox–active tyrosine denoted Y Z , a tetramanganese cluster, calcium and chloride. In 1995, Gerald Babcock and co–workers presented the hypothesis that photosynthetic water oxidation occurs as a metallo–radical catalysed process. In this model, the oxidized tyrosine radical is generated by coupled proton/electron transfer and re–reduced by abstracting hydrogen atoms from substrate water or hydroxide–ligated to the manganese cluster. The proposed function of Y Z requires proton transfer from the tyrosine site upon oxidation. The oxidation mechanism of Y Z in an inhibited and O 2 –evolving photosystem II is discussed. Domino–deprotonation from Y Z to the bulk solution is shown to be consistent with a variety of data obtained on metal–depleted samples. Experimental data that suggest that the oxidation of Y Z in O 2 –evolving samples is coupled to proton transfer in a hydrogen–bonding network are described. Finally, a dielectric–dependent model for the proton release that is associated with the catalytic cycle of photosystem II is discussed.
9

Tantawy, Waled, Ahmed Hashem, Nabil Yousif, and Eman Flefel. "The water–boryl radical as a proton-coupled electron transfer reagent for carbon dioxide, formic acid, and formaldehyde — Theoretical approach." Canadian Journal of Chemistry 91, no. 2 (February 2013): 155–68. http://dx.doi.org/10.1139/cjc-2012-0303.

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The thermochemistry of the hydrogen atom transfer reactions from the H2O–BX2 radical system (X = H, CH3, NH2, OH, F) to carbon dioxide, formic acid, and (or) formaldehyde, which produce hydroxyformyl, dihydroxymethyl, and hydroxymethyl radicals, respectively, were investigated theoretically at ROMP2/6–311+G(3DF,2P)//UB3LYP/6–31G(D) and UG3(MP2)-RAD levels of theory. Surprisingly, in the cases of a strong Lewis acid (X = H, CH3, F), the spin transfer process from the water–boryl radical to the carbonyl compounds was barrier-free and associated with a dramatic reduction in the B–H bond dissociation energy (BDE) relative to that of isolated water–borane complexes. Examining the coordinates of these reactions revealed that the entire hydrogen atom transfer process is governed by the proton-coupled electron transfer (PCET) mechanism. Hence, the elucidated mechanism has been applied in the cases of weak Lewis acids (X = NH2, OH), and the variation in the accompanied activation energy was attributed to the stereoelectronic effect interplaying in CO2 and HCOOH compared with HCHO. We ascribed the overall mechanism as a SA-induced five-center cyclic PCET, in which the proton transfers across the so-called complexation-induced hydrogen bond (CIHB) channel, while the SOMOB–LUMOC=O′ interaction is responsible for the electron migration process. Owing to previous reports that interrelate the hydrogen-bonding and the rate of proton-coupled electron-transfer reactions, we postulated that “the rate of the PCET reaction is expected to be promoted by the covalency of the hydrogen bond, and any factor that enhances this covalency could be considered an activator of the PCET process.” This postulate could be considered a good rationale for the lack of a barrier associated with the hydrogen atom transfer from the water-boryl radical system to the carbonyl compounds. Light has been shed on the water–boryl radical reagent from the thermodynamic perspective.
10

Gillet, Natacha, Bernard Lévy, Vicent Moliner, Isabelle Demachy, and Aurélien de la Lande. "Electron and Hydrogen Atom Transfers in the Hydride Carrier Protein EmoB." Journal of Chemical Theory and Computation 10, no. 11 (October 14, 2014): 5036–46. http://dx.doi.org/10.1021/ct500173y.

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Статті в журналах Дисертації

Дисертації з теми "Hydrogen atom transfers":

1

Smith, Susan Lavinia. "Chiral selection in hydrogen atom transfer reactions." Thesis, Royal Holloway, University of London, 1986. http://repository.royalholloway.ac.uk/items/f4ae87be-b444-42db-828c-b12089967742/1/.

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This thesis describes an attempt to demonstrate enantioselectivity in free-radical hydrogen transfer reactions and was designed to test a novel extension of the Hammond Postulate. It is proposed that the rates of two related reactions which are thermodynamically identical but kinetically distinct should differ most when the processes are thermoneutral since the transition state is remote from both reactant and product. Bysynthesis and subsequent oxidation of suitable chiral hydroxamic acids a series of persistent chiral acyl nitroxide radicals ArCON(R)O has been made. By reacting such a series of nitroxide radicals with suitable chiral benzylic alcohols ArCHOHR it was hoped that by varying the nature of, the bond strength of the alcohol would come within the compass of the 0-H bond strengths of ArCON(R)OH. It was predicted that such an alcohol should show a maximum in a plot of enantioselectivity vs. 0-H bond strength. The target molecules for this work were optically active N-alkylbenzohydroxamic acids in which the akyl substituent was both chiral and tertiary. Substitution of electron withdrawing and releasing groups, ranging from into the aroyl group of the hydroxamic acid and subsequent oxidation of the latter allowed the synthesis of radicals with varying bond strengths. UV-visible, e.s.r. and CD spectra were determined for these radicals. 0-H bond strengths of the hydroxamic acids were estimated using an e.s.r. technique which determined the equilibrium position for hydrogen atom transfer between the hydroxamic acid and a standard di-t-alkyl nitroxide radical which forms a bond of known strength to hydrogen. These estimated values range from 76 to 79 kcal mol. Enantoselectiviy was searched for in two ways. The first employed UV spectroscopy to determine the second order rate constants for the four possible reaction pairs of chiral nitroxide enantiomers with benzylic alcohol enantiomers. The second method involved reaction of racemic alcohol with chiral radical and subsequent examination of enantiomeric excess by high performance liquid chromatography (HPLC); two approaches to this are described. In the majority of cases studied, however, enantioselectivity was immeasurably small. In the case of 2-methyl-l-phenylpropan-l-ol, a small enantiomeric excess was observed but further work is needed to substantiate these results. Small chiral discriminations were observed in the oxidation reactions of only one alcohol. These results were insufficient to investigate the extension of the Hammond Postulate as originally planned.
2

Elayoubi, Mustapha. "Transfert d'atomes d'hydrogène vers la cathode d'un arc réducteur de composition argon-hydrogène /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1989. http://theses.uqac.ca.

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3

Pillai, Jayasheela. "Heterocycle synthesis by hydrogen atom transfer and cyclisation." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298644.

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4

Harvey, Erica Lyn Gray Harry B. "Photochemical hydrogen atom transfer reactions of binuclear platinum complexes /." Diss., Pasadena, Calif. : California Institute of Technology, 1990. http://resolver.caltech.edu/CaltechETD:etd-06112007-134908.

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5

Beaufils, Florent. "Recent developments in radical-mediated hydrogen atom transfer reaction /." [S.l.] : [s.n.], 2004. http://www.zb.unibe.ch/download/eldiss/04beaufils_f.pdf.

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6

Bouchet, Damien. "Applications de l'organocatalyse asymétrique et de la photocatalyse aux additions nucléophiles sur des dérivés α,β-insaturés électroappauvris". Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASF001.

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Les additions nucléophiles sur les accepteurs de Michael comptent parmi les réactions les plus fondamentales de la chimie organique. Elles n'ont eu de cesse d'être revisitées, notamment au gré de l'emploi de dérivés α,β-insaturés peu conventionnels. La catalyse permet de démultiplier leurs potentialités tout en s'inscrivant dans une démarche plus respectueuse de l'environnement. Aussi, cette thèse s'ouvre par une partie dédiée à l'organocatalyse asymétrique. Le premier chapitre relate le développement d'une cycloaddition (4 + 2) asymétrique promue par des isothiourées et permettant la synthèse d'anti-2,3-dihydrothiopyranones. La réactivité singulière des thiochalcones, utilisées pour la première fois en tant qu'accepteurs de Michael, y est mise en exergue. Un deuxième chapitre est consacré à une cycloaddition (3 + 2) entre des quinones diimines et des énecarbamates médiée par les acides phosphoriques chiraux. Elle a conduit à des indolines 2,3-disubstituées. Étonnamment, des produits acycliques de ζ-amination ont été formés en étendant cette transformation aux triénecarbamates. Ils résultent d'une addition 1,6 sur l'azote des quinones diimines. Afin d'optimiser la stéréosélectivité de cette transformation, nous nous sommes tournés vers l'intelligence artificielle. Une seconde partie porte sur une désaromatisation photocatalytique d'indoles électoappauvris en C3 par C2-acylation. Elle repose sur l'addition de radicaux générés à partir d'aldéhydes par un HAT direct opéré par le TBADT, un polyoxométallate
Nucleophilic additions to Michael acceptors constitute one of the most fundamental class of reactions in organic chemistry. They have been frequently revisited using unconventional α,β-unsaturated derivatives. Catalysis drastically increases their potential while falling within an environmentally-friendly approach. Hence, this manuscript begins with a first part devoted to asymmetric organocatalysis. The opening chapter focuses on the development of an asymmetric (4 + 2)-cycloaddition promoted by isothioureas. It enabled the synthesis of anti-2,3-dihydrothiopyranones while showcasing the peculiar reactivity of thiochalcones. They were used, for the first time, as Micheal acceptors. The second chapter is dedicated to a (3 + 2)-cycloaddition between quinones diimines and enecarbamates. It led to 2,3-disubstituted indolines. Surprisingly, ζ-amination acyclic products were obtained when we extended this transformation to trienecarbamates. They resulted from a 1,6-addition on the nitrogen of quinone diimines. Aiming to optimize the stereoselectivity of this transformation, we turned our attention towards artificial intelligence. A second part deals with a photocatalytic dearomatization of indoles bearing an electron-withdrawing group at C3 position via their C2-acylation. It relied on the addition of acyl radical species generated from aldehydes through a HAT mediated by a polyoxometalate: the TBADT
7

Roth, Justine P. "Intrinsic and thermodynamic influences on hydrogen atom transfer reactions involving transition metal complexes /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/11602.

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8

Støchkel, Kristian. "Electron-transfer processes in fast ion-atom collisions." Doctoral thesis, Stockholm : Department of Physics, Stockholm University, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-732.

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9

Asous, Nadia K. "Hydrogen Atom Transfer Reactivity of Bio-inspired Unsymmetrical Dicopper– oxo/peroxo Complexes." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1533245264093817.

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10

Anderson, Andrea H. "Mechanistic Studies on the Monoamine Oxidase B Catalyzed Oxidation of 1,4-Disubstituted Tetrahydropyridine Derivatives." Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/30566.

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The flavin-containing monoamine oxidases (MAO) A and B catalyze the oxidative deamination of primary and secondary amines. The overall process involves a two electron oxidation of the amine to the iminium with concomitantreduction of the flavin. Based on extensive studies with a variety of chemical probes, Silverman and colleagues have proposed a catalytic pathway for the processing of amine substrates and inactivators by MAO-B that is initiated by a single electron transfer (SET) step from the nitrogen lone pair to the oxidized flavin followed by a-proton loss from the resulting amine radical cation that leads to a carbon radical. Subsequent transfer of the second electron leads to the reduced flavin and the iminium product. In the case of N-cyclopropylamines, the initially formed amine radical cation is proposed to undergo rapid ring opening to form a highly reactive primary carbon centered radical that is thought to be responsible for inactivation of the enzyme. In this thesis we have exploited the unique substrate and inactivator properties of 1,4-disubstituted tetrahydropyridine derivatives to probe the mechanism of MAO-B catalysis. Reports of the parkinsonian inducing neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) as a structurally unique substrate of MAO-B initiated these studies. Consistent with the SET pathway, the N-cyclopropyl analog of MPTP proved to be an efficient time and concentration dependent inactivator but not a substrate of MAO-B. On the other hand, the 4-benzyl-1-cyclopropyl analog is both a substrate and inactivator of MAO-B. These properties may not be consistent with the obligatory formation of a cyclopropylaminyl radicalcation intermediate. In an attempt to gain further insight into the mechanism associated with the MAO catalyzed oxidation of 1,4-disubstituted tetrahydropyridines, deuterium isotope effects studies on both the substrate and inactivation properties of the 4-benzyl-1- cyclopropyl derivative were undertaken. A series of 1-methyl- and 1-cyclopropyltetrahydropyridine derivatives bearing various heteroaro-matic groups at C-4 also have been examined. The MAO-B substrate properties, inactivator properties and partition ratios for these compounds together with preliminary results from chemical model studies are discussed in terms of the MAO-B catalytic pathway.
Ph. D.
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Книги з теми "Hydrogen atom transfers":

1

Estes, Deven Paul. Transition Metal Hydrides that Mediate Catalytic Hydrogen Atom Transfers. [New York, N.Y.?]: [publisher not identified], 2014.

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2

Yao, Chengbo. First Row Transition Metal Hydrides Catalyzed Hydrogen Atom Transfer. [New York, N.Y.?]: [publisher not identified], 2022.

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Частини книг з теми "Hydrogen atom transfers":

1

Wang, Liang, and Jian Xiao. "Hydrogen-Atom Transfer Reactions." In Topics in Current Chemistry Collections, 205–59. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-43051-5_5.

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2

Lomas, John S. "Hydrogen Atom Transfer Between Ketyl Radicals and Ketones." In Organic Free Radicals, 105–6. Berlin, Heidelberg: Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/978-3-642-73963-7_52.

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3

Lefebvre, R. "Elements of Hydrogen Transfer Theory." In Structure and Dynamics of Atoms and Molecules: Conceptual Trends, 1–24. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0263-6_1.

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4

Manca, Carine Tanner, Christian Tanner, and Samuel Leutwyler. "Controlling Excited-State H-Atom Transfer along Hydrogen-Bonded Wires." In Hydrogen Bonding and Transfer in the Excited State, 525–54. Chichester, UK: John Wiley & Sons, Ltd, 2010. http://dx.doi.org/10.1002/9780470669143.ch23.

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5

Kravtsov, A. V. "Muon Transfer from Excited Muonic Hydrogen to Helium Nuclei." In Muonic Atoms and Molecules, 199–207. Basel: Birkhäuser Basel, 1993. http://dx.doi.org/10.1007/978-3-0348-7271-3_19.

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6

Schneuwly, H. "Muon Capture and Transfer in Gas Mixtures with Hydrogen." In Electromagnetic Cascade and Chemistry of Exotic Atoms, 205–15. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4899-3701-8_19.

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7

Warren, Jeffrey J., and James M. Mayer. "Chapter 1. Application of the Marcus Cross Relation to Hydrogen Atom Transfer/Proton-Coupled Electron Transfer Reactions." In Proton-Coupled Electron Transfer, 1–31. Cambridge: Royal Society of Chemistry, 2011. http://dx.doi.org/10.1039/9781849733168-00001.

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8

Hoshino, Mikio, and Haruo Shizuka. "Hydrogen Atom Transfer Reactions in the Excited States of Aromatic Carbonyl Photoinitiators." In Radiation Curing in Polymer Science and Technology—Volume II, 637–709. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1876-7_15.

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9

Lippert, H., V. Stert, L. Hesse, C. P. Schulz, I. V. Hertel, and W. Radloff. "Indole(NH3)n Clusters: Hydrogen Atom Transfer Initiated by Femtosecond Laser Pulses." In Ultrafast Phenomena XIII, 110–12. Berlin, Heidelberg: Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-642-59319-2_34.

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10

Miller, William H. "Reaction Paths and Surfaces for Hydrogen Atom Transfer Reactions in Polyatomic Molecules." In The Jerusalem Symposia on Quantum Chemistry and Biochemistry, 91–101. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-4752-8_8.

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Тези доповідей конференцій з теми "Hydrogen atom transfers":

1

Grothe, Rob. "Adaptive Protein Structure Refinement Using Diffraction Data." In Signal Recovery and Synthesis. Washington, D.C.: Optica Publishing Group, 1998. http://dx.doi.org/10.1364/srs.1998.swa.2.

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X-ray crystallography remains the primary technique for discovering the arrangement of a protein’s atoms in space. If this arrangement is given by a vector of atom positions r = (r 1 ,r 2 ,…,r N ), then the resulting structure factor F(r)(S) in direction S is given by where F a ( i ) is the atomic scattering function of a(i) ∈ {“Carbon", “Nitrogen", “Hydrogen",…}, the atom type of the ith atom. F a ( i ) is the Fourier transform of ρ a (i), the spherical electron density for an atom of type a(i) placed at the origin.
2

Zhang, Jiapei, Wei Li, Zhangcan Yang, and Yingzhao He. "Molecular Dynamics Simulation of Diffusion and Aggregation Behavior of Helium in Tungsten Bulk Materials." In ASME 2019 6th International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/mnhmt2019-3947.

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Abstract Controlled thermonuclear fusion is a promising project. If it can be realized, it will certainly replace fossil fuels and solve the problem of energy exhaustion facing humanity. The fusion reaction fuel is a light core, which can be extracted from sea water. The source is very rich, and the fusion reaction of hydrogen and its isotopes is not radioactive, so the fusion energy can be efficient, cheap and clean. At present, the realization of this technology still faces many difficult problems that have not been overcome. The Tokamak device is the most promising device for realizing the controlled thermonuclear fusion. It utilizes a toroidal magnetic field to confine the high temperature plasma. Among them, the choice of plasma-facing materials is the key factor that determines whether or not controlled nuclear fusion can be achieved. For the time being, tungsten is the preferred plasma-facing material. In the case of fusion, tungsten is exposed to extreme conditions such as high temperature and strong radiation, and a large number of defects are generated inside. In this thesis, the molecular dynamics software LAMMPS was used to study one of the defects, interstitial atoms, and the interaction of helium atoms to understand the diffusion and aggregation behavior of helium and the evolution of defects in tungsten. The following aspects are mainly studied: one is the calculation of the binding energy of an interstitial atom and helium atoms, the other is the study of the interstitial and helium atoms’ space configurations, and the third is comparing trap mutation in defective tungsten materials with trap mutation in tungsten materials without defects, and the fourth is the recording of the displacement of the helium atoms and the interstitial atom at temperature control. The study found that the presence of the interstitial atom will indeed affect the aggregation and diffusion of helium atoms, which will trap the movement of helium atoms and cause the helium atoms to gather near the interstitial atoms and form small clusters of helium. As the cluster grows larger, trap mutations occur like a defect-free tungsten block.
3

Tokumasu, Takashi, and Daigo Ito. "The Dependence of Molecular Motion on the Dissociative Adsorption of H2 on Pt(111)." In ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference collocated with the ASME 2007 InterPACK Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ht2007-32590.

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The dependence of molecular motion on the dissociative adsorption mechanism of hydrogen molecule (H2) on platinum (Pt) surface was studied by Molecular Dynamics (MD) method. An interaction between atoms was considered by the Embedded Atom Method (EAM). A potential between an H atom and a Pt atom was determined from results of Density Functional Theory (DFT). Dissociation probabilities of three surface conditions, that is, (1) when the surface temperature is 300 K, (2) when the surface temperature is 0 K with allowing motion of the surface atoms and (3) when the surface temperature is 0 K with prohibiting motion of the surface atoms, were obtained. From results of the simulations, the effect of surface motion on dissociation probability was analyzed as a function of initial energy of the dissociating molecule or the surface conditions. First, it was concluded that the increase in the dissociation probability of the case (3) by the increase in the initial translational energy of H2 molecule is gentle compared with those of the other cases. Additionally, the minimum initial translational energy of H2 molecule of case (3) at which the H2 molecule can dissociate is the smallest among all of three cases. It was found that this is because the range of the dissociation barrier distribution for the case (3) is wider than those for the other cases due to the thermal motion of surface atoms. Moreover, the effect of translational and rotational motion of molecule on the dissociation probability was analyzed. It was concluded that the dissociation probability increases with the increase in the translational energy while it decreases with the increase in the rotational energy when the rotational energy is small.
4

Karule, E. "Above Threshold Ionization of Hydrogen Atom in Strong ac Fields." In High Resolution Fourier Transform Spectroscopy. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/hrfts.1994.wc9.

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5

Garg, R. K., J. P. Gore, and T. S. Fisher. "Numerical Simulation of Gas Phase Reaction Chemistry in Methane-Hydrogen Mixtures." In ASME 2003 Heat Transfer Summer Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/ht2003-47474.

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In the present work, gas-phase reactions between opposing streams of mixtures of hydrogen (H2) and methane (CH4) in the presence of volumetric energy input were simulated. The goal of the simulations is to estimate the concentrations of precursors responsible for the formation of carbon nanotubes (CNTs). These estimates are expected to help in understanding fundamental mechanisms of CNT formation and in controlling the synthesis process through parameters such as inlet composition and temperature, reactor pressure and absorbed energy. The simulation employs gas-phase kinetics of the GRI-2.11 mechanism with only reactions involving molecules that contain C and H atoms. The results indicate that the concentrations of H radicals, C2H2 and C atoms increase significantly with increases in volumetric energy deposition rate beyond a threshold.
6

Stert, V., L. Hesse, H. Lippert, C. P. Schulz, and W. Radloff. "Indole(NH3)n clusters: hydrogen atom transfer initiated by femtosecond laser pulses." In International Conference on Ultrafast Phenomena. Washington, D.C.: OSA, 2002. http://dx.doi.org/10.1364/up.2002.me15.

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7

Porterfield, Malcolm, and Diana Borca-Tasciuc. "Molecular Dynamics Simulation of Ultra-Fast Phase Transition in Water Nanofilms." In ASME 2020 Heat Transfer Summer Conference collocated with the ASME 2020 Fluids Engineering Division Summer Meeting and the ASME 2020 18th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/ht2020-9073.

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Abstract Molecular dynamics simulations are used to explore explosive boiling of thin water films on a gold substrate. In particular, water films of 2.5, 1.6 and 0.7 nanometer thickness were examined. Three different surface wettabilities with contact angles of 11, 47 and 110 degrees were simulated along with substrate temperatures of 400K, 600K, 800K and 1000K. The 11 degree contact angle was obtained using a Morse interaction potential between the water film and the gold substrate while the 47 and 110 degree contact angles were obtained via a Lennard-Jones potential. Evaporation was the first mode of phase change observed in all cases and explosive boiling did not occur until the substrate reached a temperature of 800K. When explosive boiling was present for all three contact angles, it was consistently shown to occur first for the surface with a 47 degree contact angle, contrary to the expectation that it would occur first on the substrate with an 11 degree contact angle. These results suggest that explosive boiling onset is strongly dependent on the particularities of the interaction potential. For instance, the Morse potential used to model the surface described by an 11 degree contact angle, is a softer potential as compared with Lennard-Jones, but has more interaction sites per molecule — two hydrogen atoms and one oxygen atom vs one oxygen atom. Thus, although the water film reaches a higher temperature with the Morse potential, explosive boiling onset is delayed as more interaction sites have to be disrupted. These results suggest that both the interaction strength and the number of atoms interacting at the interface must be considered when investigating trends of explosive boiling with surface wettability.
8

Fang, Jin, and Laurent Pilon. "Effect of Hydrogen Passivation on the Thermal Conductivity of Nanoporous Crystalline Silicon: A Molecular Dynamics Study." In ASME 2012 Third International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/mnhmt2012-75153.

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Effect of hydrogen passivation on thermal conductivity of nanoporous crystalline silicon was investigated using equilibrium molecular dynamics (MD) simulations from 500 to 1000 K. The porosity varied from 8% to 38% while the pore diameter ranged from 1.74 to 2.93 nm. Hydrogen passivation of the pore surface was found to reduce thermal conductivity by about 20% at 500 K due to enhanced phonon scattering by the passivated atoms at the nanopore surface. The effect of passivation diminished with increasing temperature. In fact, the phonon density of states at high temperatures was similar for both passivated and unpassivated silicon atoms. Finally, the thermal conductivity k was found to be linearly proportional to (1–1.5fv)/(Ai/4) where fv is the porosity and Ai is the pore interfacial area concentration. This scaling law was previously established for un-passivated silicon using non-equilibrium MD simulations.
9

Esposito, Fabrizio. "Detailed cross section calculations of atom-molecule energy transfer processes and dissociation for hydrogen, nitrogen and oxygen." In ATOMIC AND MOLECULAR DATA AND THEIR APPLICATIONS: Joint Meeting of 14th Internat. Toki Conf. on Plasma Physics and Controlled Nuclear Fusion (ITC14); and 4th Internat. Conf. on Atomic and Molecular Data and Their Applications (ICAMDATA2004). AIP, 2005. http://dx.doi.org/10.1063/1.1944712.

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10

Tao, Yi, Chenhan Liu, Juekuan Yang, Kedong Bi, Weiyu Chen, and Yunfei Chen. "First Principles Study of Thermal Conductance Across Cu/Graphene/Cu Nanocomposition and the Effect of Hydrogenation." In ASME 2016 5th International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/mnhmt2016-6318.

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In this work, the interfacial thermal conductance across Cu/graphene/Cu interfaces is investigated using the density functional theory (DFT) and the nonequilibrium Green’s function (NEGF) method. In order to study how hydrogenation of graphene affects thermal transport behaviors at the interfaces of Cu/graphene/Cu, we also analyze the interfacial thermal conductance across Cu/hydrogenated-graphene/Cu (Cu/H-graphene/Cu) with both double-sided and single-sided hydrogenated graphene. Our results show that, the interfacial thermal conductance across Cu/H-graphene/Cu interfaces is almost twice of the value across Cu/graphene/Cu interfaces. For Cu/H-graphene/Cu with double-sided hydrogenated graphene (Cu/DH-graphene/Cu), the hydrogen atoms between graphene and Cu layers provide additional thermal transport channels. While for Cu/H-graphene/Cu with single-sided hydrogenated graphene (Cu/SH-graphene/Cu), the hydrogen atoms not only provide additional thermal transport channels at the hydrogenated side of graphene, but also reduce the equilibrium separation between graphene and Cu layers at the non-hydrogenated side of graphene due to the transfer of massive electrons, which enhances the interface coupling between graphene and Cu layers. The phonon transmission shows that both double-sided and single-sided hydrogenation of graphene can increase the heat transport across the interface. Our calculation indicates that the interfacial thermal conductance of Cu/graphene/Cu nanocomposition can be improved by hydrogenation.

Звіти організацій з теми "Hydrogen atom transfers":

1

Ferguson, John Michael. Thermally-generated reactive intermediates: Trapping of the parent ferrocene-based o-quinodimethane and reactions of diradicals generated by hydrogen-atom transfers. Office of Scientific and Technical Information (OSTI), September 1993. http://dx.doi.org/10.2172/10185328.

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2

Patil, Bhimanagouda S., Ron Porat, G. K. Jayaprakasha, and K. N. C. Murthy. Optimization of Postharvest Storage Conditions to Maintain Fruit Quality and Health Maintaining Properties of Grapefruit. United States Department of Agriculture, January 2010. http://dx.doi.org/10.32747/2010.7613879.bard.

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Antioxidant activity of fruits is gaining wide interest among consumers due to its importance in counteracting oxidative stress, free radicals and preventing DNA damage. Oxygen radical absorbance capacity (ORAC) assay is one of the commonly used assays to measure the antioxidant activity, which is based on hydrogen atom transfer mechanism. Furocoumarins present in grapefruit are reported to have antiproliferative activity, induce GST activity, inhibit biofilm formation and increase bioavailability of drugs. In the present project ORAC values were measured of Star Ruby grapefruit undergone ethylene degreening treatment, cold storage and temperature conditioning treatment, and modified atmosphere packaging which were stored at different temperatures for prolonged period. In addition, furocoumarins were quantified in Star Ruby grapefruits from cold storage and conditioning experiment conducted in Israel. Conditioning treatment is practiced prior cold storage to reduce chilling injury in grapefruits during cold storage for prolonged period. Levels of 6,7-dihyrdoxy bergamottin decreased during storage period in all three treatments.

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