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81.
Dr. Marwa Abdelmouleh Dr. Mathieu Lalande Edith Nicol Dr. Gilles Frison Prof. Dr. Guillaume van der Rest Dr. Jean-Christophe Poully 《Chemphyschem》2021,22(12):1243-1250
These last decades, it has been widely assumed that 18-crown-6-ether (CE) plays a spectator role during the chemical processes occurring in isolated host-guest complexes between peptides or proteins and CE after activation in mass spectrometers. Our present experimental and theoretical results challenge this hypothesis by showing that CE can abstract a proton or a protonated molecule from protonated peptides after activation by collisions in argon or electron capture/transfer. Furthermore, thanks to comparison between experimental and calculated values of collision cross-sections, we demonstrate that CE can change binding site after electron transfer. We also propose detailed mechanisms for these processes. 相似文献
82.
Chenglin Miao Fengyu Zhang Luoyu Cai Tianli Hui Junting Feng Dianqing Li 《ChemCatChem》2021,13(23):4937-4947
Focusing on the simultaneous enhancement of activity and selectivity in α, β-unsaturated aldehyde hydrogenation, we designed and prepared an ultrathin CoAl-LDH supported Pt catalyst. A series of technologies revealed the ultrathin CoAl-LDH support possesses the characteristic of dual defects, oxygen vacancy (VO) and cobalt vacancy (VCo). Then, two kinds of vacancy related interface sites were identified, namely Pt−VO−Coδ+ and Pt−VCo−OHδ−. Compared with the bulk catalyst, the ultrathin catalyst exhibits both enhanced intrinsic activity and C=O bond selectivity under the synergistic effect of the dual interface sites. Specifically, the Pt−VO−Coδ+ interface site changes the adsorption mode of cinnamaldehyde and promotes the activation of C=O bonds, thus leading to the improved cinnamyl alcohol selectivity. The H atoms of the Pt−VCo−OHδ− interface site participate in the hydrogenation process, which facilitates the mobility of active hydrogen and therefore promotes the intrinsic activity. More importantly, the ultrathin catalyst shows good reusability. 相似文献
83.
The electrophoresis and electric conduction of a suspension of charged spherical particles in a salt-free solution are analyzed by using a unit cell model. The linearized Poisson-Boltzmann equation (valid for the cases of relatively low surface charge density or high volume fraction of the particles) and Laplace equation are solved for the equilibrium electric potential profile and its perturbation caused by the imposed electric field, respectively, in the fluid containing the counterions only around the particle, and the ionic continuity equation and modified Stokes equations are solved for the electrochemical potential energy and fluid flow fields, respectively. Explicit analytical formulas for the electrophoretic mobility of the particles and effective electric conductivity of the suspension are obtained, and the particle interaction effects on these transport properties are significant and interesting. The scaled zeta potential, electrophoretic mobility, and effective electric conductivity increase monotonically with an increase in the scaled surface charge density of the particles and in general decrease with an increase in the particle volume fraction, keeping each other parameter unchanged. Under the Debye-Hückel approximation, the dependence of the electrophoretic mobility normalized with the surface charge density on the ratio of the particle radius to the Debye screening length and particle volume fraction in a salt-free suspension is same as that in a salt-containing suspension, but the variation of the effective electric conductivity with the particle volume fraction in a salt-free suspension is found to be quite different from that in a suspension containing added electrolyte. 相似文献
84.
Currently, feature annotation remains one of the main challenges in untargeted metabolomics. In this context, the information provided by high-resolution mass spectrometry (HRMS) in addition to accurate mass can improve the quality of metabolite annotation, and MS/MS fragmentation patterns are widely used. Accurate mass and a separation index, such as retention time or effective mobility (μeff), in chromatographic and electrophoretic approaches, respectively, must be used for unequivocal metabolite identification. The possibility of measuring collision cross-section (CCS) values by using ion mobility (IM) is becoming increasingly popular in metabolomic studies thanks to the new generation of IM mass spectrometers. Based on their similar separation mechanisms involving electric field and the size of the compounds, the complementarity of DTCCSN2 and μeff needs to be evaluated. In this study, a comparison of DTCCSN2 and μeff was achieved in the context of feature identification ability in untargeted metabolomics by capillary zone electrophoresis (CZE) coupled with HRMS. This study confirms the high correlation of DTCCSN2 with the mass of the studied metabolites as well as the orthogonality between accurate mass and μeff, making this combination particularly interesting for the identification of several endogenous metabolites. The use of IM-MS remains of great interest for facilitating the annotation of neutral metabolites present in the electroosmotic flow (EOF) that are poorly or not separated by CZE. 相似文献
85.
Shui-Yang Lien Yu-Hao Chen Wen-Ray Chen Chuan-Hsi Liu Chien-Jung Huang 《Molecules (Basel, Switzerland)》2021,26(15)
In this study, adding CsPbI3 quantum dots to organic perovskite methylamine lead triiodide (CH3NH3PbI3) to form a doped perovskite film filmed by different temperatures was found to effectively reduce the formation of unsaturated metal Pb. Doping a small amount of CsPbI3 quantum dots could enhance thermal stability and improve surface defects. The electron mobility of the doped film was 2.5 times higher than the pristine film. This was a major breakthrough for inorganic quantum dot doped organic perovskite thin films. 相似文献
86.
Mikhail Yu. Ivanov Sergey A. Prikhod&#x;ko Olga D. Bakulina Alexey S. Kiryutin Nicolay Yu. Adonin Matvey V. Fedin 《Molecules (Basel, Switzerland)》2021,26(19)
Ionic liquid (IL) glasses have recently drawn much interest as unusual media with unique physicochemical properties. In particular, anomalous suppression of molecular mobility in imidazolium IL glasses vs. increasing temperature was evidenced by pulse Electron Paramagnetic Resonance (EPR) spectroscopy. Although such behavior has been proven to originate from dynamics of alkyl chains of IL cations, the role of electron spin relaxation induced by surrounding protons still remains unclear. In this work we synthesized two deuterated imidazolium-based ILs to reduce electron–nuclear couplings between radical probe and alkyl chains of IL, and investigated molecular mobility in these glasses. The obtained trends were found closely similar for deuterated and protonated analogs, thus excluding the relaxation-induced artifacts and reliably demonstrating structural grounds of the observed anomalies in heterogeneous IL glasses. 相似文献
87.
Pierre-Alexis Rpcaud Monica Ceretti Mimoun Aouine Cline Delwaulle Emmanuel Nonnet Werner Paulus Helena Kaper 《Molecules (Basel, Switzerland)》2021,26(21)
The support material can play an important role in oxidation catalysis, notably for CO oxidation. Here, we study two materials of the Brownmillerite family, CaFeO2.5 and SrFeO2.5, as one example of a stoichiometric phase (CaFeO2.5, CFO) and one existing in different modifications (SrFeO2.75, SrFeO2.875 and SrFeO3, SFO). The two materials are synthesized using two synthesis methods, one bottom-up approach via a complexation route and one top-down method (electric arc fusion), allowing to study the impact of the specific surface area on the oxygen mobility and catalytic performance. CO oxidation on 18O-exchanged materials shows that oxygen from SFO participates in the reaction as soon as the reaction starts, while for CFO, this onset takes place 185 °C after reaction onset. This indicates that the structure of the support material has an impact on the catalytic performance. We report here on significant differences in the catalytic activity linked to long-term stability of CFO and SFO, which is an important parameter not only for possible applications, but equally to better understand the mechanism of the catalytic activity itself. 相似文献
88.
The purpose of this article is to investigate high‐order numerical approximations of scalar conservation laws with nonlocal viscous term. The viscous term is given in the form of convolution in space variable. With the help of the characteristic of viscous term, we design a semidiscrete local discontinuous Galerkin (LDG) method to solve the nonlocal model. We prove stability and convergence of semidiscrete LDG method in L2 norm. The theoretical analysis reveals that the present numerical scheme is stable with optimal convergence order for the linear case, and it is stable with sub‐optimal convergence order for nonlinear case. To demonstrate the validity and accuracy of our scheme, we test the Burgers equation with two typical nonlocal fractional viscous terms. The numerical results show the convergence order accuracy in space for both linear and nonlinear cases. Some numerical simulations are provided to show the robustness and effectiveness of the present numerical scheme. 相似文献
89.
In order to investigate the effects of thermoultrasonic treatment (TUT) on the formation of colloidal micro-nano particles (MNPs) and the quality of halibut bone soup, nutrients, particle characteristics, and flavor characteristics were analyzed. The morphology of MNPs was studied using an optical microscope. Results showed that TUT could increase the nutrient content (total sugars, 22.15 mg/100 mL; water soluble proteins, 173.24 mg/mL; fatty acids, 1779.7 mg/100 mL; solids, 3.16 g/100 mL), reduce the particle size (605.92 nm) and interfacial tension. Meanwhile, TUT make the halibut bone soup has better emulsifying characteristics and stability. The contents of flavor substances, such as esters, 5′-nucleotides, organic acids in the halibut bone soup were more abundant, while the contents of hexanal and 1-octen-3-ol and fishy off-flavor were reduced in TUT group. The overall odor and taste outline were more harmonious. Therefore, TUT can be used in the production of high quality fish bone soup, and TUT could be considered as a good deep processing technology for halibut bone and improve economic efficiency. 相似文献
90.
Hiroyuki Ohshima 《Colloid and polymer science》2007,285(13):1411-1421
Theories of electrokinetics of soft particles, which are particles covered with an ion-penetrable surface layer of polyelectrolytes,
are reviewed. Approximate analytic expressions are given, which describe various electrokinetics of soft particles both in
dilute and concentrated suspensions, that is, electrophoretic mobility, electrical conductivity, sedimentation velocity and
potential, dynamic electrophoretic mobility, colloid vibration potential, and electrophoretic mobility under salt-free condition. 相似文献