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31.
Yunusa Umar Sahar Abdalla SK Manirul Haque Guillermo Salgado Moran Abdurrahman Ishaq Wilson Cardona Villada Jorge Dagnino Leone Marta Bunster 《中国化学会会志》2020,67(1):62-71
The optimized molecular structures, harmonic vibrational wavenumbers, and the corresponding vibrational assignments of (1S,2S)-tramadol and (1R,2R)-tramadol are computationally examined using the B3LYP density functional theory method together with the standard 6–311++G(d,p) and def2-TVZP basis sets. The optimized structures show that phenolic rings of both 1R,2R and 1S,2S tramadol adopt planar geometry, which are slightly distorted due to the substitution at the meta-position; and the six-membered cyclohexane adopts a slightly distorted chair conformation. The 1S,2S enantiomer is energetically more favorable than 1R,2R with the energy differences of 1.32 and 1.03 kcal/mol obtained at B3LYP/6–311++G(d,p) and B3LYP/Def2-TVZP levels, respectively. The analysis of the binding pocket in the silico molecular docking with the m-opioid receptor shows that it originated two clusters with the 1S,2S enantiomer and one cluster with the 1R,2R enantiomer of tramadol. The results point to a more stable complex of the m-opioid receptor with the 1R,2R enantiomer of tramadol. 相似文献
32.
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34.
G. Montagnoli S. Beghini F. Scarlassara A.M. Stefanini L. Corradi C.J. Lin G. Pollarolo Aage Winther 《The European Physical Journal A - Hadrons and Nuclei》2002,15(3):351-356
The two systems 40Ca + 90,96Zr have been studied by measuring nucleon transfer reactions at two energies near the Coulomb barrier, thus complementing
the available sub-barrier fusion cross-sections. Angular distributions for various transfer channels have been determined.
Significantly larger neutron transfer cross-sections are found for the target 96Zr that exhibits the larger enhancement in the sub-barrier fusion cross-sections. All data have been analyzed with a new model
for heavy-ion collisions that calculates simultaneously transfer cross-sections, fusion excitation functions and barrier distributions.
The model gives a good account of both transfer and fusion data.
Received: 2 May 2002 / Accepted: 4 June 2002 / Published online: 26 November 2002
RID="a"
ID="a"e-mail: montagnoli@pd.infn.it, Fax +39049 8277102, Tel. +39049 8277117.
RID="b"
ID="b"On leave from the China Institute for Atomic Energy, 102413 Beijing, China.
Communicated by C. Signorini 相似文献
35.
Summary We report on calculations of differential and total ionization cross-sections of hydrogen atoms irradiated by two radiation
fields with different properties. One of the fields is of low intensity and relatively high frequency, the other is of low
frequency and high intensity. In particular, we show that the inclusion of the multimode structure of the low-frequency laser
field modifies considerably the shape of the angular distribution of the photoelectrons and the rates of ionization into the
different channels characterized by the number of low-frequency photons exchanged. Further, we find that the average energy
exchanged between the photoelectrons and the low-frequency radiation field is independent of the statistical properties of
the low-frequency laser field. 相似文献
36.
G. Corradi V.S. Vikhnin Yu.S. Gromovoi I.M. Zaritskii 《Journal of Physics and Chemistry of Solids》1981,42(11):995-1007
An experimental and theoretical investigation of the spin-lattice relaxation (SLR) mechanisms of VK-centers in alkali and alkaline earth halides has been carried out. It has been shown that at low temperatures the main role in SLR is played by rapidly relaxing centers (RRC). In some cases, however, an intrinsic one-phonon SLR process due to modulation of both the isotropic and anisotropic hyperfine (HF) interaction seems to be important. At higher temperatures SLR can be explained by an anharmonic Raman process with the participation of the resonant molecular vibrational (RMV) mode of the VK-center. In this SLR process, similarly to the low-temperature intrinsic process, the spin-phonon coupling is due to the modulation of the HF interaction. Deviations from the Debye phonon spectrum and the local anharmonicity of VK-centers turn out to be important. The SLR of several other hole and interstitial type centers in alkali halides has also been investigated and their SLR mechanisms are discussed. 相似文献
37.
An experimental investigation of the gas-phase photooxidation of toluene–NOx–air mixtures at part-per-million concentrations has been carried out in a 65-m3, outdoor smog chamber to assess our understanding of the atmospheric chemistry of toluene. In addition, six CO? NOx–air irradiations were conducted to characterize the chamber with regard to any wall radical sources. Measured parameters in the toluene–NOx experiments included O3, NO, NO2, HNO3, peroxyacetyl nitrate (PAN), CO, toluene, benzaldehyde, o-cresol, m-nitrotoluene, peroxybenzoyl nitrate (PBZN), temperature, relative humidity, aerosol size distributions, and particulate organic carbon. Predictions of the reaction mechanism of Leone and Seinfeld [7] are found to be in good agreement with the data under a variety of initial conditions. Additional simulations are used to investigate various mechanistic pathways in areas where our understanding of toluene chemistry is still incomplete. 相似文献
38.
We study the low temperature properties of p-spin glass models with finite connectivity and of some optimization problems. Using a one-step functional replica symmetry breaking ansatz we can solve exactly the saddle-point equations for graphs with uniform connectivity. The resulting ground state energy is in perfect agreement with numerical simulations. For fluctuating connectivity graphs, the same ansatz can be used in a variational way: For p-spin models (known as p-XOR-SAT in computer science) it provides the exact configurational entropy together with the dynamical and static critical connectivities (for p = 3, gamma(d) = 0.818, and gamma(s) = 0.918), whereas for hard optimization problems like 3-SAT or Bicoloring it provides new upper bounds for their critical thresholds ( gamma(var)(c) = 4.396 and gamma(var)(c) = 2.149). 相似文献
39.
Comparison of the filamentation and the hollow-core fiber characteristics for pulse compression into the few-cycle regime 总被引:1,自引:0,他引:1
L. Gallmann T. Pfeifer P.M. Nagel M.J. Abel D.M. Neumark S.R. Leone 《Applied physics. B, Lasers and optics》2007,86(4):561-566
The gas-filled hollow-core fiber compression and the optical filamentation technique are compared experimentally in a parameter
regime suitable for intense few-cycle pulse generation. In particular, pointing stability, spectral properties, and spatial
chirp are investigated. It is found that in the case of filamentation, the critical parameter for pointing stability is gas
pressure inside the generation cell whereas for the hollow-core fiber it is alignment that plays this role. The hollow-core
fiber technique yields spectra that are better suited for chirped-mirror pulse compression whereas filamentation offers higher
throughput and prospects for easy-to-implement self-compression. We present spectral phase interferometry for direct electric-field
reconstruction (SPIDER) measurements that directly show the transition in the spectral phase of the output continua into the
self-compression regime as the gas pressure is increased.
PACS 42.65.Re; 42.65.Jx; 42.65.Tg 相似文献
40.
P. Mason N. Marginean G. Montagnoli S. Beghini F. Scarlassara E. Farnea C. A. Ur A. Meroni A. M. Stefanini L. Corradi E. Fioretto I. V. Pokrovskiy B. Guiot A. Gadea J. J. Valiente-Dobón F. Della Vedova R. Orlandi E. Sahin D. R. Napoli L. Berti N. Toniolo S. Szilner M. Trotta M. Romoli M. La Commara D. Pierroutsakou M. Sandoli G. Pollarolo G. Benzoni 《The European physical journal. Special topics》2007,150(1):359-361
PRISMA is a magnetic
spectrometer installed at Laboratori Nazionali di Legnaro (Italy)
and designed for A=100–200, E=5–10 MeV-per-nucleon beams, and for
possible use with the proposed radioactive beam facility SPES. The
foremost features of the instrument are presented, along with the
outline of two data analyses exemplifying the effectiveness of
PRISMA-CLARA in studies of reaction
dynamics. 相似文献