排序方式: 共有58条查询结果,搜索用时 15 毫秒
1.
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
2.
In this study, methanol extracts (MEs) and essential oil (EO) of Angelica purpurascens (Avé-Lall.) Gill obtained from different parts (root, stem, leaf, and seed) were evaluated in terms of antioxidant activity, total phenolics, compositions of phenolic compound, and essential oil with the methods of 2,2-azino-bis(3ethylbenzo-thiazoline-6-sulfonic acid (ABTS•+), 2,2-diphenyl-1-picrylhydrazil (DPPH•) radical scavenging activities, and ferric reducing/antioxidant power (FRAP), the Folin–Ciocalteu, liquid chromatography−tandem mass spectrometry (LC−MS/MS), and gas chromatography-mass spectrometry (GC−MS), respectively. The root extract of A. purpurascens exhibited the highest ABTS•+, DPPH•, and FRAP activities (IC50: 0.05 ± 0.0001 mg/mL, IC50: 0.06 ± 0.002 mg/mL, 821.04 ± 15.96 µM TEAC (Trolox equivalent antioxidant capacity), respectively). Moreover, EO of A. purpurascens root displayed DPPH• scavenging activity (IC50: 2.95 ± 0.084 mg/mL). The root extract had the highest total phenolic content (438.75 ± 16.39 GAE (gallic acid equivalent), µg/mL)). Twenty compounds were identified by LC−MS/MS. The most abundant phenolics were ferulic acid (244.39 ± 15.64 μg/g extract), benzoic acid (138.18 ± 8.84 μg/g extract), oleuropein (78.04 ± 4.99 μg/g extract), and rutin (31.21 ± 2.00 μg/g extract) in seed, stem, root, and leaf extracts, respectively. According to the GC−MS analysis, the major components were determined as α-bisabolol (22.93%), cubebol (14.39%), α-pinene (11.63%), and α-limonene (9.41%) among 29 compounds. Consequently, the MEs and EO of A. purpurascens can be used as a natural antioxidant source. 相似文献
3.
We present a cw, Nd:YAG-pumped singly resonant single-frequency narrow-linewidth high-power optical parametric oscillator with idler tuning from 3.7 to 4.7 microm. In this spectral range the absorption of the idler wave in the LiNbO3 crystal is significant, causing the oscillation threshold to increase with a subsequent decrease in output power from 1.2 W at 3.9 microm to 120 mW at 4.7 microm. The optical parametric oscillator's cavity was stabilized and mode-hop tuned with a rotatable solid etalon but with a subsequent reduction in idler power of as much as 50%. We demonstrated the usefulness for spectroscopy by recording the photoacoustic spectrum of a strong CO2 absorption, using a 24-GHz continuous idler scan. 相似文献
4.
Jean-Francois Bisson Hideki Yagi Takakimi Yanagitani Alexander Kaminskii Yuri N. Barabanenkov Ken-Ichi Ueda 《Optical Review》2007,14(1):1-13
Grain boundaries play a key role in determining several key properties of polycrystalline laser ceramics. Heat transfer measurements
at low temperature constitute a good tool to probe grain boundaries. We review the results of heat transfer measurements in
polycrystalline Y3Al5O12 garnets as well as Y2O3 and Lu2O3 sesquioxide materials obtained by self-energy-driven sintering of nano-particles. The average phonon mean free path in Y3Al5O12 was found to be significantly larger than the average grain size and to scale with temperature as T
−2 at low temperature. Existing models describing the interaction between phonons and grain boundaries are reviewed. Correct
temperature dependence of the mean free path and order of magnitude of scattering rates were found by assuming the existence
of a grain boundary layer having acoustic properties different from those of the bulk. A different temperature dependence
of phonon mean free path was found for the sesquioxides and was ascribed to the stronger elastic anisotropy of these materials.
The thermal resistance associated to the grain boundaries of laser ceramics was found to be lower than in other dense polycrystalline
ceramic materials reported in the literature. 相似文献
5.
Bisson J Poupard P Pawlus AD Pons A Darriet P Mérillon JM Waffo-Téguo P 《Journal of chromatography. A》2011,1218(36):6079-6084
The phytochemical study of the root extract of the stilbenoid-rich Vitis riparia × Vitis berlandieri grapevine was carried out by centrifugal partition chromatography (CPC). For this reason, we developed a new elution mode we named back-step, which allowed us to obtain cleaner fractions and a more efficient separation process when used in conjunction with a classical elution approach. Three hydroxystilbenes: (E)-resveratrol, (E)-?-viniferin and (E)-vitisin C, with greater than 90% purity were thus obtained through such process, with minimal sample handling and purification steps. Online coupling of CPC to ESI mass spectrometry was used for optimization of the separation parameters and to facilitate the characterization of the stilbenoids. This study details the first phytochemical investigation of stilbenoids from the hybrid species together with a new elution mode able to widen the range of ARIZONA biphasic systems. 相似文献
6.
We present two algorithms to compute the endomorphism ring of an ordinary elliptic curve E defined over a finite field Fq. Under suitable heuristic assumptions, both have subexponential complexity. We bound the complexity of the first algorithm in terms of , while our bound for the second algorithm depends primarily on log|DE|, where DE is the discriminant of the order isomorphic to End(E). As a byproduct, our method yields a short certificate that may be used to verify that the endomorphism ring is as claimed. 相似文献
7.
Using previously determined interatomic potentials, the activation energy for migration of a single substitutional helium atom in copper and tungsten has been determined. The mechanism of migration involves the jump of the helium atom out of the vacancy concurrent with the jump of a host atom into that vacancy. The helium then occupies the vacant site created by the jumping host atom, resulting in a substitutional helium at a distance of √2 r 0 (√3r 0) from its original site in copper (tungsten). The rate-limiting step in the process is found to be the jump of the helium out of the vacancy, the activation energy for which is 2.15 eV in copper and 4.69 eV in tungsten. 相似文献
8.
Bekzat ABDIKADYR Alp KILI Onur ALEV Serkan BÜYÜKK
SE Zafer Ziya
ZTÜRK 《Turkish Journal of Chemistry》2021,45(2):295
Pristine and WO3 decorated TiO2 nanorods (NRs) were synthesised to investigate n-n-type heterojunction gas sensing properties. TiO2 NRs were fabricated via hydrothermal method on fluorine-doped tin oxide coated glass (FTO) substrates. Then, tungsten was sputtered on the TiO2 NRs and thermally oxidised to obtain WO3 nanoparticles. The heterostructure was characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopy. Fabricated sensor devices were exposed to VOCs such as toluene, xylene, acetone and ethanol, and humidity at different operation temperatures. Experimental results demonstrated that the heterostructure has better sensor response toward ethanol at 200 °C. Enhanced sensing properties are attributed to the heterojunction formation by decorating TiO2 NRs with WO3. 相似文献
9.
M. Bernaschi M. Bisson M. Fatica E. Phillips 《The European physical journal. Special topics》2012,210(1):17-31
We present and compare different approaches for using multiple Graphics Processing Units in the simulation of physical systems. As benchmarks we consider the time required to update a single spin of the 3D Heisenberg spin glass model, by using both the Over-relaxation and the Heat Bath algorithms, and the solution of a Poisson equation by using a finite-difference method. The results show that a suitable combination of techniques allows to hide almost completely the communication overhead by using the CPU as a communication coprocessor of the GPU. Large scale simulations on clusters of GPUs can be efficiently carried out by following the same approach for other applications where a clear cut exists between bulk and boundaries data. 相似文献
10.
J.-F. Bisson O. Parriaux J.C. Pommier S. Tonchev K. Ueda 《Applied physics. B, Lasers and optics》2006,85(4):519-524
A resonant grating mirror was monolithically integrated to an ytterbium-doped ceramic Y3Al5O12 microchip laser to produce a linearly polarized laser beam emitting at 1030 nm with a polarization contrast ratio up to 1000. The device was pumped with a fiber-coupled laser diode bar emitting 2-ms pulses at 50 Hz at 940 nm. Up to 13-W peak output power was obtained from 20-W absorbed pump power at room temperature. The obtained slope efficiency with respect to the absorbed pump power was about 80%. PACS 42.40.Lx; 42.55.-f; 42.60.Jf; 42.60.Lh; 42.55.Xi; 42.70.Hj 相似文献