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排序方式: 共有134条查询结果,搜索用时 15 毫秒
31.
Celine Nadal Satya N. Majumdar Massimo Vergassola 《Journal of statistical physics》2011,142(2):403-438
We compute analytically the statistics of the Renyi and von Neumann entropies (standard measures of entanglement), for a random
pure state in a large bipartite quantum system. The full probability distribution is computed by first mapping the problem
to a random matrix model and then using a Coulomb gas method. We identify three different regimes in the entropy distribution,
which correspond to two phase transitions in the associated Coulomb gas. The two critical points correspond to sudden changes
in the shape of the Coulomb charge density: the appearance of an integrable singularity at the origin for the first critical
point, and the detachment of the rightmost charge (largest eigenvalue) from the sea of the other charges at the second critical
point. Analytical results are verified by Monte Carlo numerical simulations. A short account of part of these results appeared
recently in Nadal et al. (Phys. Rev. Lett. 104:110501, 2010). 相似文献
32.
Alexander A. Kokhanovsky Vladimir P. Budak Celine Cornet Minzheng Duan Claudia Emde Iosif L. Katsev Dmitriy A. Klyukov Sergey V. Korkin L. C-Labonnote Bernhard Mayer Qilong Min Teruyuki Nakajima Yoshifumi Ota Alexander S. Prikhach Vladimir V. Rozanov Tatsuya Yokota Eleonora P. Zege 《Journal of Quantitative Spectroscopy & Radiative Transfer》2010,111(12-13):1931-1946
In this paper seven vector radiative transfer codes are inter-compared for the case of underlying black surface. They include three techniques based on the discrete ordinate method (DOM), two Monte-Carlo methods, the successive orders scattering method, and a modified doubling-adding technique. It was found that all codes give very similar results. Therefore, we were able to produce benchmark results for the Stokes parameters both for reflected and transmitted light in the cases of molecular, aerosol and cloudy multiply scattering media. It was assumed that the single scattering albedo is equal to one. Benchmark results have been provided by several studies before, including Coulson et al. [22], Garcia and Siewert [7], [8], Wauben and Hovenier [10], and Natraj et al. [11] among others. However, the case of the elongated phase functions such as for a cloud and with a high angular resolution is presented here for the first time. Also in difference with other studies, we make inter-comparisons using several codes for the same input dataset, which enables us to quantify the corresponding errors more accurately. 相似文献
33.
Lavisse S Rouffiac V Peronneau P Paci A Chaix C Reb P Roche A Lassau N 《Ultrasonics》2008,48(1):16-25
The objective of the study was to acoustically characterize trisacryl polymeric microparticles (TMP), which are derived from biocompatible embolic agents.With significant acoustic properties, these polymeric particles could be potentially used as targeted ultrasound contrast agents, directed towards a specific site, with ligands conjugation on the polymeric network surface. In the in vitro study, a pulser/receiver (PRF of 1 kHz), associated to different transducers (5, 10 and 15 MHz), was used to measure the acoustic properties of the TMP inserted in a Couette flow device. Acoustic characterization according to TMP concentration (0.12-15.63 mg/ml), frequency (4.5-17 MHz, defined by each transducer bandwidth), ultrasound pressure (137-378 kPa) and exposure time (0-30 min) was conducted. Particle attenuation was also evaluated according to TMP concentration and emission frequency. Backscattering increased non linearly with concentration and maximum enhancement was of 16.4 dB ± 0.89 dB above 7.8 mg/ml. This parameter was found non-linear with increasing applied pressure and no harmonic oscillation could be noticed. Attenuation reached approximately 1.4 dB/cm at 15 MHz and for the 15.6 mg/ml suspension.The TMP have revealed in vitro ultrasound properties comparable to those observed with known contrast agents, studied in similar in vitro systems. However, such set-ups combined with a rather aqueous suspending medium, have some limitations and further investigations need now to be conducted to approach in vivo conditions in terms of flow and blood environment. 相似文献
34.
在200℃脉冲吸附吡啶或2,6—二甲基吡啶饱和后,进行TPD实验。结果表明,无论是总酸还是B酸都随铈含量的增加而降低。脉冲吸附碱法比TPD法所得酸量大,在Pt-Ce/v-Al2O3催化剂中,主要是B酸,B酸和总酸的TM值随铈含量的变化而异。总酸的TM(TM≈290℃)降低,B酸的TM(TM≈265℃)增高 相似文献
35.
R. Fermento D.C. Leitao J.M. Teixeira A.M. Pereira F. Carpinteiro J. Ventura J.P. Araujo J.B. Sousa 《Journal of Non》2008,354(47-51):5279-5281
Magnetic nanostructures display new and interesting physical phenomena and are currently used in a large variety of applications. We studied the structural, magnetic and transport properties of Co thin films deposited by ion beam sputtering. We probed the influence of the buffer layer material (Al, Cu, Ru or Ta) and thickness (10–100 Å) on the structural properties of Co thin films. Using X-ray diffraction we observed that textured fcc Co films can be grown on amorphous Ta as thin as 20 Å but for the other buffer layers no texture is observed. We also studied by magneto-optical Kerr effect (MOKE) the magnetic properties of the Co thin films as a function of Co thickness (100–1000 Å). Finally, the electrical resistivity and anisotropic magnetoresistance (AMR) of our Co thin films (on a Ta buffer) was obtained as a function of Co thickness. 相似文献
36.
Laurence Latu-Romain Celine Mouchet Cyril Cayron Emmanuelle Rouviere Jean-Pierre Simonato 《Journal of nanoparticle research》2008,10(8):1287-1291
In this paper the effect of varying temperature, pressure and chemical precursors on the vapour–liquid–solid (VLS) growth
of silicon nanowires (Si NWs) have been investigated. Some aspects of nucleation and growth mechanisms are discussed. Control
on Si NW morphology by varying the choice of gaseous precursor (silane or dichlorosilane) at elevated temperatures is reported. 相似文献
37.
Cedric Pardanaud Celine Martin Gilles Cartry Ahmad Ahmad Loic Schiesko Gregory Giacometti Marcel Carrere Pascale Roubin 《Journal of Raman spectroscopy : JRS》2015,46(2):256-265
Graphite samples exposed to H, D and He plasma at fluencies from 1016 to 1018 cm−2 have been investigated by means of atomic force and Raman microscopies. The ion energy was varied between 40 and 800 eV, and the ion incidence was either perpendicular (Highly Oriented Pyrolitic Graphite) or parallel (carbon/carbon composite) to the basal plane. When increasing the impinging ion energy, the growth of nanometric domes at the surface has been observed by atomic force microscopy and the incident kinetic energy has been found as the parameter determining their height. Two different Raman signatures related to (1) a graphitic nano‐crystalline component similar to that of a 1014 cm−2 bombarded 1‐, 2‐ and 3‐layer graphene, and to (2) an amorphous component, have been evidenced. Polarization studies have revealed that these components are related to regions with either in‐plane or out‐of‐plane disorder, coexisting in the material. These Raman studies have also revealed that both the defect–defect distance in the first case and the aromatic domain size in the second case are typically 1 nm. When the number of vacancies created in the material increases, the number of in‐plane defects decreases to the benefit of the out‐of‐plane defects. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
38.
Dr. Francesco Zaccaria Dr. Stephanie C. C. van der Lubbe Celine Nieuwland Dr. Trevor A. Hamlin Prof. Dr. Célia Fonseca Guerra 《Chemphyschem》2021,22(22):2286-2296
The formation of guanine quadruplexes (GQ) in DNA is crucial in telomere homeostasis and regulation of gene expression. Pollution metals can interfere with these DNA superstructures upon coordination. In this work, we study the affinity of the internal GQ channel site towards alkaline earth metal (Mg2+, Ca2+, Sr2+, and Ba2+), and (post-)transition metal (Zn2+, Cd2+, Hg2+, and Pb2+) cations using density functional theory computations. We find that divalent cations generally bind to the GQ cavity with a higher affinity than conventional monovalent cations (e. g. K+). Importantly, we establish the nature of the cation-GQ interaction and highlight the relationship between ionic and nuclear charge, and the electrostatic and covalent interactions. The covalent interaction strength plays an important role in the cation affinity and can be traced back to the relative stabilization of cations’ unoccupied atomic orbitals. Overall, our findings contribute to a deeper understanding of how pollution metals could induce genomic instability. 相似文献
39.
40.
Griffith D Krot K Comiskey J Nolan KB Marmion CJ 《Dalton transactions (Cambridge, England : 2003)》2008,(1):137-147
The synthesis and spectroscopic characterisation of novel mononuclear Ru(III)(edta)(hydroxamato) complexes of general formula [Ru(H2edta)(monoha)] (where monoha = 3- or 4-NH2, 2-, 3- or 4-C1 and 3-Me-phenylhydroxamato), as well as the first example of a Ru(III)-N-aryl aromatic hydroxamate, [Ru(H2edta)(N-Me-bha)].H2O (N-Me-bha = N-methylbenzohydroxamato) are reported. Three dinuclear Ru(III) complexes with bridging dihydroxamato ligands of general formula [{Ru(H2edta)}2(mu-diha)] where diha = 2,6-pyridinedihydroxamato and 1,3- or 1,4-benzodihydroxamato, the first of their kind with Ru(III), are also described. The speciation of all of these systems (with the exception of the Ru-1,4-benzodihydroxamic acid and Ru-N-methylbenzohydroxamic systems) in aqueous solution was investigated. We previously proposed that nitrosyl abstraction from hydroxamic acids by Ru(III) involves initial formation of Ru(III)-hydroxamates. Yet, until now, no data on the rate of nitric oxide (NO) release from hydroxamic acids has been published. We now describe a UV-VIS spectroscopic study, where we monitored the decrease in the ligand-to-metal charge-transfer band of a series of Ru(III)-monohydroxamates with time, with a view to gaining an insight into the NO-releasing properties of hydroxamic acids. 相似文献