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Energy spectra for decaying 2D turbulence in a bounded domain 总被引:1,自引:0,他引:1
We use results derived in the framework of the replica approach to study the liquid-glass thermodynamic transition. The main results are derived without using replicas and applied to the study of the Lennard-Jones binary mixture introduced by Kob and Andersen. We find that there is a phase transition due to the entropy crisis. We compute both analytically and numerically the value of the phase transition point T(K) and the specific heat in the low temperature phase. 相似文献
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Vessecchi R Zocolo GJ Gouvea DR Hübner F Cramer B de Marchi MR Humpf HU Lopes NP 《Rapid communications in mass spectrometry : RCM》2011,25(14):2020-2026
This paper reports theoretical and experimental studies of gas‐phase fragmentation reactions of four naturally occurring isoflavones. The samples were analyzed in negative ion mode by direct infusion in ESI‐QqQ, ESI‐QqTOF and ESI‐Orbitrap systems. The MS/MS and MSn spectra are in agreement with the fragmentation proposals and high‐resolution analyses have confirmed the formulae for each ion observed. As expected, compounds with methoxyl aromatic substitution have showed a radical elimination of ?CH3 as the main fragmentation pathway. A second radical loss (?H) occurs as previously observed for compounds which exhibit a previous homolytic ?CH3 cleavage (radical anion) and involves radical resonance to stabilize the anion formed. However, in this study we suggest another mechanism for the formation of the main ions, on the basis of the enthalpies for each species. Compounds without methoxy substituent dissociate at the highest energies and exhibit the deprotonated molecule as the most intense ion. Finally, energy‐resolved experiments were carried out to give more details about the gas‐phase dissociation reaction of the isoflavones and the results are in agreement with the theoretical approaches. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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de Souza Caroline Gondim Martins Fátima Itana Chaves Custódio Zocolo Guilherme Julião Figueiredo José Edson Fontes Canuto Kirley Marques de Brito Edy Sousa 《Analytical and bioanalytical chemistry》2018,410(26):6827-6836
Analytical and Bioanalytical Chemistry - The rapid and accurate quantification of lipopeptide families in biological samples are challenging. We present the development and validation of a method... 相似文献
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Mora JF Van Berkel GJ Enke CG Cole RB Martinez-Sanchez M Fenn JB 《Journal of mass spectrometry : JMS》2000,35(8):939-952
Editorial Comment Last month we presented, as a Special Feature, a set of five articles that constituted a Commentary on the fundamentals and mechanism of electrospray ionization (ESI). These articles produced some lively discussion among the authors on the role of electrochemistry in ESI. Six authors participated in a detailed exchange of views on this topic, the final results of which constitute this month's Special Feature. We particularly hope that younger scientists will find value in this month's Special Feature, not only for the science that it teaches but also what it reveals about the processes by which scientific conclusions are drawn. To a degree, the contributions part the curtains on these processes and show science in action. We sincerely thank the contributors to this discussion. The give and take of intellectual debate is not always easy, and to a remarkable extent this set of authors has maintained good humor and friendships, even when disagreeing strongly on substance. Graham Cooks and Richard Caprioli Copyright 2000 John Wiley & Sons, Ltd. 相似文献
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Van Berkel GJ Quirke JM Adams CL 《Rapid communications in mass spectrometry : RCM》2000,14(10):849-858
A survey of derivatization strategies and prospective derivatization reactions for conversion of simple alkenes and alkynes to 'electrospray-active' species is presented. General synthetic strategies are discussed and illustrative examples of prospective derivatives prepared from model compounds are presented along with their electrospray ionization (ES) mass spectra. The identified derivatives of these neutral, nonpolar analytes are either ionic or are ionizable in solution through Bronsted acid/base chemistry, by Lewis acid/base chemistry, or by chemical or electrochemical electron-transfer chemistry. Once ionized, the derivatives are expected to be amenable to detection by electrospray ionization-mass spectrometry. Derivatives are identified for positive and negative ion analysis of both alkenes and alkynes. Copyright 2000 John Wiley & Sons, Ltd. 相似文献
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