Search results for "Proton"
showing 10 items of 5886 documents
Y:BaZrO 3 Perovskite Compounds II: Designing Protonic Conduction by using MD Models
2011
The proton dynamics in Y-doped BaZrO(3) derivatives, in particular the different dopant environments within a Pm3m cubic framework, were studied by using classical molecular dynamics (MD) calculations. Single- and double substitution of zirconium by yttrium atoms was considered. The presence of yttrium induced variations in the surrounding oxygen sites, according to their local geometrical arrangements. The differences among such distinct oxygen sites became evident when protons interacted with them and upon changes in the temperature. So, different proton transfer pathways, which had different energy barriers, characterized the topologically different oxygen sites. The experimental proton-…
“Two-Story” Calix[6]arene-Based Zinc and Copper Complexes: Structure, Properties, and O 2 Binding
2017
International audience; A new “two-story” calix[6]arene-based ligand was synthesized, and its coordination chemistry was explored. It presents a tren cap connected to the calixarene small rim through three amido spacers. X-ray diffraction studies of its metal complexes revealed a six-coordinate ZnII complex with all of the carbonyl groups of the amido arms bound and a five-coordinate CuII complex with only one amido arm bound. These dicationic complexes were poorly responsive toward exogenous neutral donors, but the amido arms were readily displaced by small anions or deprotonated with a base to give the corresponding monocationic complexes. Cyclic voltammetry in various solvents showed a r…
Radial electron fluence around ion tracks as a new physical parameter for the detection threshold of PADC using Geant4-DNA toolkit
2018
International audience; The detection threshold of poly(allyl dyglycol carbonate), PADC, for C ions is determined as 55 eV/nm in stopping power, which is significantly higher than that for proton and He ions. The stopping power is not a universal parameter for expressing the detection threshold of PADC. A new physical parameter of Radial Electron Fluence around Ion Tracks, REFIT, is proposed to describe the detection threshold of PADC. It is defined as the number density of electrons passing through the surface of a cylinder of a certain radius that is co-axial with the trajectory. Furthermore, preliminary calculations are presently being performed using the Monte Carlo simulation code of G…
PTR-SRI-ToF-MS analysis of aroma compounds: influence of drift tube E/N ratio on sensitivity and fragmentattion
2013
Livre ISBN-13 : 978-3-902811-91-2; International audience; The aim of this work was to compare detection and fragmentation patterns of aroma compounds obtained with three different precursor ions and several E/N source parameter values with the proton transfer reaction (PTR-MS) methodology. The reactant ions H3O+, NO+ and O2+. were generated in a Switchable Reagent Ions (SRI) source of a PTR-ToF-MS (Ionicon 8000, Innsbruck, Austria). Precursor ions plasmas were characterized at different E/N ratio in the drift tube. For proton transfer reaction, the hydronium primary ion was the most abundant ion (> 80%) for all E/N ratios above 120 Td, but the sensitivity decreased quickly with the highest…
In vivo aroma release by APCI-MS and PTR-MS: impact of water content of exhaled air and evidence for competition between aroma compounds
2013
Livre ISBN-13 : 978-3-902811-91-2; International audience; Atmospheric pressure chemical ionization mass spectrometry (APCI-MS) or proton transfer reaction mass spectrometry (PTR-MS) has been in use frequently for in vivo aroma release studies. In APCI-MS, protonated water clusters formed from moisture in the expired air are used as reagent ions. Yet the influence of a change in relative water content in the ionization gas on the data collected have been rarely studied and conflicting results were obtained. In this context our first objective was to study the impact of water content of the expired air on the level of aroma release measured by APCI-MS and to compare with the results obtained…
Incident use of proton pump inhibitors in France, 2015
2018
IF 2.314; International audience
Interaction between plasma membrane H+ -ATPase and phytotoxins : use of reconstituted systems
1989
International audience
Acid−Base Properties of Synthetic and Natural Polyelectrolytes: Experimental Results and Models for the Dependence on Different Aqueous Media
2008
Protonation constants of several natural and synthetic humates and fulvates were determined by ISE-H+ potentiometry in different ionic media (alkali metal halides and tetraethylammonium iodide) at different ionic strengths and T ) 298.15 K. Experimental data obtained in previous studies of different synthetic (polyacrylates, polymethacrylates, polyacrylate-co-maleate) and naturally occurring (alginate, humic substances) polycarboxylates were also taken into account in the general analysis of acid-base properties of polyelectrolytes. Protonation constants were expressed as a function of the dissociation degree (R) using three models, namely, a simple linear model, the Ho¨gfeldt three-paramet…
Speciation Studies of Bifunctional 3-Hydroxy-4-Pyridinone Ligands in the Presence of Zn2+ at Different Ionic Strengths and Temperatures
2019
The acid&ndash
Microscopic Insights Into the Formation of Methanesulfonic Acid–Methylamine–Ammonia Particles Under Acid-Rich Conditions
2022
Understanding the microscopic mechanisms of new particle formation under acid-rich conditions is of significance in atmospheric science. Using quantum chemistry calculations, we investigated the microscopic formation mechanism of methanesulfonic acid (MSA)–methylamine (MA)–ammonia (NH3) clusters. We focused on the binary (MSA)2n-(MA)n and ternary (MSA)3n-(MA)n-(NH3)n, (n = 1–4) systems which contain more acid than base molecules. We found that the lowest-energy isomers in each system possess considerable thermodynamic and dynamic stabilities. In studied cluster structures, all bases are protonated, and they form stable ion pairs with MSA, which contribute to the charge transfer and the stab…