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991.
Andrzej Eilmes 《International journal of quantum chemistry》2014,114(4):261-270
Effect of molecular vibrations on the absorption spectra simulated via a sequential approach combining molecular dynamics (MD) with quantum‐chemical calculations has been investigated. Simulated spectra have been obtained from the time‐dependent density functional theory results averaged over series of molecular geometries retrieved from Born–Oppenheimer MD trajectories. Distributions of bond lengths have been analyzed and related to the features of calculated spectra. For NVE simulations of small systems, absorption spectra exhibit bimodal bandshape as a result of classical treatment of vibrations. For NVE trajectories of larger systems or simulations in the NVT ensemble calculated absorption bands are symmetric, however, they may not agree with the results of Franck–Condon analysis. These results are practical manifestations of effects predicted theoretically from general principles. Consequences for the modeling of absorption spectra have been discussed. © 2013 Wiley Periodicals, Inc. 相似文献
992.
The synthesis of diethyl [2-(2-alkyl-3-oxo-2,3-dihydro-1H-isoindol-1-yl)ethyl]phosphonates and diethyl [3-(2-alkyl-3-oxo-2,3-dihydro-1H-isoindol-1-yl)propyl]phosphonates, via metallation (sec-BuLi) of N-substituted isoindolin-1-ones and then the reaction of the generated lithiated species 4 with diethyl vinylphosphonate or diethyl 3-bromopropylphosphonate, respectively, is described. 相似文献
993.
Marcin Stec Adam Tatarczuk Dariusz Śpiewak Andrzej Wilk 《Journal of solution chemistry》2014,43(5):959-971
The densities of aqueous mixtures of aminoethylethanolamine (CAS #000111-41-1) were measured over the entire compositional range at temperatures of 283.15–343.15 K. The results of these measurements were used to calculate excess molar volumes and isobaric thermal expansion coefficients, and partial molar and apparent molar volumes and excess isobaric thermal expansion coefficients were subsequently derived. The excess molar volumes were correlated as a function of the mole fraction using the Redlich–Kister equation. Temperature dependences of the Redlich–Kister coefficients are also presented. The partial molar volumes at infinite dilution of AEEA in water were determined using two different methods. In addition, the solution density was correlated using a Joubian–Acree model. Aqueous solutions of AEEA exhibit similar properties to the aqueous solutions of other alkanolamines (like monoethanolamine) used in acid gas sweetening. 相似文献
994.
Andrzej Buchacz 《PAMM》2015,15(1):381-382
In this paper the analysis of torsionally vibrating subsystem of complex mechanical and mechatronic systems by using the the exact and approximate methods were the main purposes to solve the task of assignment of frequency-modal analysis and characteristics of mechatronic system. The characteristic of the elementary subsystems using the exact and approximate methods has been determined according to accepted frequencies and the correction coefficient. The frequencies were chosen from the spectrum in which the synthesis of complex systems will be conducted. It is very important that the difference of flexibility values in the spectrum was minimal. The coefficient of the correction has been determined according to the flexibility values of chosen points and it is equal to quotient of flexibility calculated using the exact method across the flexibility delivered by using the approximate method. The coefficient of the correction is the zero-dimensional quantity. After determination of the correction coefficient the medium value which has been afterwards considered in correlation of dynamic characteristics has been calculated. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
995.
Tomasz Jakubczyk Wojciech Pacuski Paweł Duch Piotr Godlewski Andrzej Golnik Carsten Kruse Detlef Hommel Jan A. Gaj 《Central European Journal of Physics》2011,9(2):428-431
We investigate light emission from ZnTe-based microcavities containing CdTe quantum dots (QDs), with 2D (planar cavity) and
0D (pillar cavities) photonic confinement. The angular distribution from the planar cavity is presented as well as 2D cross-sections
of the far field distribution of radiation from the micropillars. The efficient and desirable modification of the isotropic
radiation of the QDs is shown for such structures. The diffraction observed is found to be inherent for such experiments with
large numerical aperture of the lens and small diameters of the investigated pillars. This diffraction is successfully modeled. 相似文献
996.
Starowicz M Starowicz P Zukrowski J Przewo?nik J Lemański A Kapusta C Bana? J 《Journal of nanoparticle research》2011,13(12):7167-7176
We present a novel and facile method enabling synthesis of iron oxide nanoparticles, which are composed mainly of maghemite according to X-ray diffraction (XRD) and Mössbauer spectroscopy studies. The proposed process is realized by anodic iron polarization in deaerated LiCl solutions containing both water and ethanol. Water seems to play an important role in the synthesis. Morphology of the product was studied by means of transmission electron microscopy and XRD. In the solution containing almost 100% of water a black suspension of round shaped maghemite nanoparticles of 20–40 nm size is obtained. Regulating water concentration allows to control nanoparticle size, which is reduced to 4–6 nm for 5% of water with a possibility to reach intermediate sizes. For 3% or lower water concentration nanoparticles are of a needle-like shape and form a reddish suspension. In this case phase determination is problematic due to a small particle size with the thickness of roughly 3 nm. However, XRD studies indicate the presence of ferrihydrite. Coercivities of the materials are similar to those reported for nanoparticle magnetite powders, whereas the saturation magnetization values are considerably smaller. 相似文献
997.
998.
Andrzej Okninski 《International Journal of Theoretical Physics》2011,50(3):729-736
We study subsolutions of the Dirac and Duffin-Kemmer-Petiau equations described in our earlier papers. It is shown that subsolutions
of the Duffin-Kemmer-Petiau equations and those of the Dirac equation obey the same Dirac equation with some built-in projection
operator. This covariant equation can be referred to as supersymmetric since it has bosonic as well as fermionic degrees of
freedom. 相似文献
999.
We study the nonlinear evolution of a weakly perturbed anti-de?Sitter (AdS) space by solving numerically the four-dimensional spherically symmetric Einstein-massless-scalar field equations with negative cosmological constant. Our results suggest that AdS space is unstable under arbitrarily small generic perturbations. We conjecture that this instability is triggered by a resonant mode mixing which gives rise to diffusion of energy from low to high frequencies. 相似文献
1000.
Effect of oxygen surface groups on adsorption of benzene derivatives from aqueous solutions onto active carbon samples 总被引:1,自引:0,他引:1
The process of adsorption of selected benzene derivatives from aqueous solution is investigated on two carbonaceous materials of differentiated surface properties - quantity of oxygen functional groups. Carbon samples were prepared by removal of external layers from granules of unmodified and oxidized active carbon. The surface and structure characteristics of carbon samples were estimated by various methods. The experimental isotherms of organics adsorption from liquid phase were measured and interpreted in terms of the theory of adsorption on heterogeneous solid surfaces. The influence of differences in adsorbate and adsorbent properties on adsorption uptake was analyzed. The adsorption effectiveness was regarded as a result of the differences in adsorbate hydrophobicities and the effect of specific interactions of its functional groups with active sites on carbon surface. 相似文献