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91.
We present a novel technique that intrinsically mitigates the quantum-defect heating in Raman lasers. The basic principle of this so-called "coherent anti-Stokes Raman scattering (CARS)-based heat mitigation" is to suppress the phonon creation in the Raman medium by increasing the number of out-coupled anti-Stokes photons with respect to the number of out-coupled Stokes photons. We demonstrate with the aid of numerical simulations that for a hydrogen and a silicon Raman laser, CARS-based heat mitigation efficiencies of at least 30% and 35%, respectively, can be obtained. 相似文献
92.
We propose a fully ab initio approach to calculate electron-phonon scattering times for excited electrons interacting with short-wavelength (intervalley) phonons in semiconductors. Our approach is based on density functional perturbation theory and on the direct integration of electronic scattering probabilities over all possible final states with no ad hoc assumptions. We apply it to the deexcitation of hot electrons in GaAs, and calculate the lifetime of the direct exciton in GaP, both in excellent agreement with experiments. Matrix elements of the electron-phonon coupling, and their dependence on the wave vector of the final state and on the phonon modes, are shown to be crucial ingredients of the evaluation of electron-phonon scattering times. 相似文献
93.
94.
Combining Complementary Ligands into one Framework for the Construction of a Ferromagnetically Coupled [MnIII12] Wheel 下载免费PDF全文
Dr. Sergio Sanz Jamie M. Frost Thayalan Rajeshkumar Dr. Scott J. Dalgarno Dr. Gopalan Rajaraman Dr. Wolfgang Wernsdorfer Prof. Jürgen Schnack Dr. Paul. J. Lusby Prof. Euan K. Brechin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(11):3010-3013
Phenolic oxime and diethanolamine moieties have been combined into one organic framework, resulting in the formation of a novel ligand type that can be employed to construct a rare and unusual dodecametallic Mn wheel, within which nearest neighbours are coupled ferromagnetically. 相似文献
95.
Dr. Florie Lavigne Dr. Eddy Maerten Dr. Gilles Alcaraz Dr. Nathalie Saffon‐Merceron Dr. Antoine Baceiredo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(1):297-303
We recently disclosed the synthesis of a novel “push–pull” boryl(phosphino)carbene. To determine the influence of this substitution pattern on the chemical behaviour, a study into the reactivity of the prototype ( 1 ) of this new family of B(sp2)‐substituted phosphinocarbenes was undertaken. Carbene 1 exhibits one of the most common intramolecular rearrangements of singlet carbenes, involving a 1,2‐mesityl shift, and typical [2+1] cycloaddition reactions with electron‐poor acrylonitrile. A pronounced α,β‐ambiphilic character was also shown by the reaction of 1 with benzaldehyde, leading to phosphorylalkene 4 . Due to its specific electronic properties, carbene 1 also exhibits unprecedented reactivity with chloroacrylonitrile, enabling the formation of bicyclo[1.1.0]phosphetanium salt 6 and borylcyclopropene 9 , which have been fully characterised by NMR spectroscopy and X‐ray crystallography. 相似文献
96.
1,10‐Phenanthroline and Non‐Symmetrical 1,3,5‐Triazine Dipicolinamide‐Based Ligands For Group Actinide Extraction 下载免费PDF全文
Dr. Julia Bisson Dr. Jérémy Dehaudt Dr. Marie‐Christine Charbonnel Dr. Denis Guillaneux Dr. Manuel Miguirditchian Dr. Cécile Marie Nathalie Boubals Guy Dutech Dr. Muriel Pipelier Dr. Virginie Blot Prof. Didier Dubreuil 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(25):7819-7829
The synthesis and evaluation of new extractants for spent nuclear fuel reprocessing are described. New bitopic ligands constituted of phenanthroline and 1,3,5‐triazine cores functionalized by picolinamide groups were designed. Synthetic routes were investigated and optimized to obtain twelve new polyaza‐heterocyclic ligands. In particular, an efficient and versatile methodology was developed to access non‐symmetric 2‐substituted‐4,6‐di(6‐picolin‐2‐yl)‐1,3,5‐triazines from the 1,3,5‐triazapentadiene precursor in the presence of anhydride reagents. Extraction studies showed the ability of both ligand series to extract and separate actinides selectively at different oxidation states (UVI, NpV,VI, AmIII, CmIII, and PuIV) from an acidic solution (3 M HNO3). Phenanthroline‐based ligands show the most promising efficiency for use in the group actinide extraction (GANEX) process due to a higher number of donor nitrogen atoms and a suitable pre‐organization of the dipicolinamide‐1,10‐phenanthroline architecture. 相似文献
97.
Dr. Sébastien Prévost Dr. Nathalie Dupré Markus Leutzsch Dr. Qinggang Wang Dr. Vijay Wakchaure Prof. Dr. Benjamin List 《Angewandte Chemie (International ed. in English)》2014,53(33):8770-8773
An asymmetric Torgov cyclization, catalyzed by a novel, highly Brønsted acidic dinitro‐substituted disulfonimide, is described. The reaction delivers the Torgov diene and various analogues with excellent yields and enantioselectivity. This method was applied in a very short synthesis of (+)‐estrone. 相似文献
98.
Back Cover: Assessment of DNA Binding to Human Rad51 Protein by using Quartz Crystal Microbalance and Atomic Force Microscopy: Effects of ADP and BRC4‐28 Peptide Inhibitor (ChemPhysChem 17/2014) 下载免费PDF全文
99.
TiO2-mediated photocatalysis is widely used in a variety of applications and products in the environmental and energy fields, including photoelectrochemical conversion, self-cleaning surfaces, and especially water purification systems. The dimensionality of the structure of a TiO2 material can affect its properties, functions, and more specifically, its photocatalytic performance. In this work, the photocatalytic inactivation of Gram-negative Escherichia coli using three photocatalysts, differing in their structure and other characteristics, was studied in a batch reactor under UVA light. The aim was to establish the disinfection efficiency of solid TiO2 compared with that of suspended catalysts, widely considered as reference cases for photocatalytic water disinfection. The bacterial inactivation profiles obtained showed that: (1) the photoinactivation was exclusively related to the quantity of photons retained per unit of treated volume, irrespective of the characteristics of the photocatalyst and the emitted light flux densities; (2) across the whole UV light range studied, each of the photocatalytic solids was able to achieve more than 2 log bacterial inactivation with less than 2 h UV irradiation; (3) none of the used catalysts achieved a total bacterial disinfection during the treatment time. For each of the catalysts the quantum yield has been assessed in terms of disinfection efficiency, the 2D material showed almost the same performance as those of suspended catalysts. This catalyst is promising for supported photocatalysis applications. 相似文献
100.
Nathalie Azaroual Jamal El Bakali Delphine Le Broc Carole Deghaye Amaury Farce Philippe Chavatte Régis Millet Claude Vaccher Emmanuelle Lipka-Belloli 《Journal of inclusion phenomena and macrocyclic chemistry》2014,78(1-4):265-274
Three selective CB2 cannabinoid receptor ligands have recently been discovered to be promising anti-inflammatory agents but their low water solubility hinder their per os administration. The popularity of the cyclodextrins, from a pharmaceutical standpoint lies on their ability to interact with poorly water-soluble drugs and improve their solubility. Herein, three experimental approaches for calculating the stability constant of complexes between the selective CB2 ligands and either the β-CD or the HP-β-CD, were tested: nuclear magnetic resonance, micellar electrokinetic chromatography and high performance liquid chromatography in reversed phase. In NMR studies the calculated K values were relatively high and were between 1486 and 3571 M?1 with β-CD. With HP-β-CD they were between 1203 and 2650 M?1. Concerning the two others techniques the K values were found lower. In MECK studies with β-CD they were between 308 and 792 M?1 and with HP-β-CD between 124 and 764 M?1. Finally in RP-HPLC studies with β-CD, they were between 539 and 1144 M?1 and with HP-β-CD between 196 and 396 M?1. These calculated constants suggest that a complexation phenomenon occurs. A model for inclusion of one of the CB2 ligands in the β-CD was then proposed from molecular modeling studies. 相似文献