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991.
Adil Mouahid David Bessieres Frédéric Plantier Gilles Pijaudier-Cabot 《Journal of Thermal Analysis and Calorimetry》2012,109(2):1077-1087
In order to assess and improve the quality of high pressure and temperature adsorption isotherms and differential enthalpies of adsorption on microporous and mesoporous materials, a specific thermostated device comprising a differential heat flow calorimeter coupled with a home-built manometric system has been built. The differential heat flow calorimeter is a Tian Calvet Setaram C80 model which can be operated isothermally, the manometric system is a stainless steel homemade apparatus. The thermostated coupled apparatus allows measurements for pressure up to 2.5?MPa and temperature from 303 to 423?K. Reliability and reproducibility were established by measuring adsorption isotherms on a benchmark sorbent (Filtrasorb F400). A detailed experimental study of the adsorption of pure carbon dioxide and methane has been made on activated carbons (Filtrasorb F400 and EcoSorb); a new procedure for determining the differential enthalpies of adsorption based on the stepwise method is also proposed. The error in the determination of the amount adsorbed is about 3.6%, and the error in the determination of the differential enthalpies of adsorption is 4%. 相似文献
992.
Dr. Brice Kauffmann Dr. Gilles Guichard 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(44):15684-15692
Anion binding properties of neutral helical foldamers consisting of urea type units in their backbone have been investigated. 1H NMR titration studies in various organic solvents including DMSO suggest that the interaction between aliphatic oligoureas and anions (CH3COO?, H2PO4?, Cl?) is site‐specific, as it largely involves the urea NHs located at the terminal end of the helix (positive pole of the helix), which do not participate to the helical intramolecular hydrogen‐bonding network. This mode of binding parallels that found in proteins in which anion‐binding sites are frequently found at the N‐terminus of an α‐helix. 1H NMR studies suggest that the helix of oligoureas remains largely folded upon anion binding, even in the presence of a large excess of the anion. This study points to potentially useful applications of oligourea helices for the selective recognition of small guest molecules. 相似文献
993.
Alkoxyallene‐ynes: Selective Preparation of Bicyclo[5.3.0] Ring Systems Including a δ‐Alkoxy Cyclopentadienone
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Dr. Aurélien Tap Camille Lecourt Sabrina Dhambri Mathieu Arnould Dr. Gilles Galvani Dr. Olivier Nguyen Van Buu Dr. Morgan Jouanneau Dr. Jean‐Pierre Férézou Prof. Janick Ardisson Dr. Marie‐Isabelle Lannou Dr. Geoffroy Sorin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(14):4938-4944
The development of an intramolecular rhodium(I)‐catalyzed Pauson–Khand reaction of alkoxyallene‐ynes with a proximal alkoxy group is reported. This reaction, in the presence of a [Rh(cycloocta‐1,5‐diene)Cl]2/propane‐1,3‐diylbis(diphenylphosphane) system under a CO atmosphere, constitutes a powerful tool for selectively accessing carbo‐ and heterobicyclo[5.3.0] frameworks featuring an enol ether moiety. Through this procedure, a straightforward access to guaiane skeletons with a tertiary hydroxy group at the C10 position was achieved. 相似文献
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995.
Margarida S. Miranda Luís Pinto da Silva Joaquim C. G. Esteves da Silva 《Journal of Physical Organic Chemistry》2014,27(1):47-56
2‐Ethylhexyl 4‐methoxycinnamate (EHMC) is a very commonly used UVB filter that is known to isomerize from the (E) to the (Z) isomer in the presence of light. In this study, we have performed high level quantum chemical calculations using density functional theory (DFT) with the B3LYP density functional and extended basis sets to study the gas‐phase molecular structure of EHMC and its energetic stability. Calculations were also performed for related smaller molecules cinnamic acid and 4‐methoxycinnamic acid. Charge delocalization has been analyzed using natural charges and Wiberg bond indexes within the natural bond orbital analysis and using nucleus independent chemical shifts. Density functional theory calculations reveal that the (E) isomer of EHMC is more stable than the (Z) by about 20 kJ mol?1 in both the gas and aqueous phases. The enthalpy of formation in the gas phase of (E)‐EHMC was derived from an isodesmic bond separation reaction. Long‐range corrected DFT calculations in implicit water were made in order to understand the excited state properties of the (E) and (Z) isomers of EHMC. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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1000.
The Dempster-Shafer theory of belief functions has proved to be a powerful formalism for uncertain reasoning. However, belief
functions on a finite frame of discernment Ω are usually defined in the power set 2Ω, resulting in exponential complexity of the operations involved in this framework, such as combination rules. When Ω is linearly
ordered, a usual trick is to work only with intervals, which drastically reduces the complexity of calculations. In this paper,
we show that this trick can be extrapolated to frames endowed with an arbitrary lattice structure, not necessarily a linear
order. This principle makes it possible to apply the Dempster-Shafer framework to very large frames such as the power set,
the set of partitions, or the set of preorders of a finite set. Applications to multi-label classification, ensemble clustering
and preference aggregation are demonstrated. 相似文献