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71.
Valdés A Prosmiti R Villarreal P Delgado-Barrio G 《The Journal of chemical physics》2011,135(24):244309
Benchmark, full-dimensional calculations on the ground and excited vibrational states for the tetra-, and penta-atomic weakly bound He(2,3)ICl complexes are reported. The representation of the potential energy surfaces includes three-body HeICl potentials parameterized to coupled-cluster singles, doubles, and perturbative triples ab initio data. These terms are important in accurately describing the interactions of such highly floppy systems. The corresponding 6D/9D computations are performed with the multi-configuration time dependent Hartree method, using natural potential fits, and a mode combination scheme to optimize the computational effort in the improved relaxation calculations. For these complexes several low-lying vibrational states are computed, and their binding energies and radial/angular probability density distributions are obtained. We found various isomers which are assigned to different structural models related with combinations of the triatomic isomers, like linear, T-shaped, and antilinear ones. Comparison of these results with recent experimental data is presented, and the quantitative deviations found with respect to the experiment are discussed. 相似文献
72.
José O. Valderrama Alvaro Toro Roberto E. Rojas 《The Journal of chemical thermodynamics》2011,43(7):1068-1073
A simple and accurate group contribution method to estimate the heat capacity of ionic liquids is presented. The method considers groups previously defined for a successful method used to estimate critical properties of ionic liquids. Additionally a structural parameter known as mass connectivity index recently defined by the authors has been incorporated to define the model equation. To better define the values of the groups, heat capacity data at 298 K for 126 organic substances were used with the 469 heat capacity data for 32 ionic liquids. The results were compared with experimental data and with values reported by other available estimation methods. Results show that the new group contribution method gives low deviations and can be used with confidence in thermodynamic and engineering calculations. 相似文献
73.
Ferraz RC Fontana CR Ribeiro AP Trindade FZ Bartoloni FH Baader JW Lins EC Bagnato VS Kurachi C 《Journal of photochemistry and photobiology. B, Biology》2011,103(2):87-92
The photodynamic therapy (PDT) is a combination of using a photosensitizer agent, light and oxygen that can cause oxidative cellular damage. This technique is applied in several cases, including for microbial control. The most extensively studied light sources for this purpose are lasers and LED-based systems. Few studies treat alternative light sources based PDT. Sources which present flexibility, portability and economic advantages are of great interest. In this study, we evaluated the in vitro feasibility for the use of chemiluminescence as a PDT light source to induce Staphylococcus aureus reduction. The Photogem? concentration varied from 0 to 75 μg/ml and the illumination time varied from 60 min to 240 min.The long exposure time was necessary due to the low irradiance achieved with chemiluminescence reaction at μW/cm2 level. The results demonstrated an effective microbial reduction of around 98% for the highest photosensitizer concentration and light dose. These data suggest the potential use of chemiluminescence as a light source for PDT microbial control, with advantages in terms of flexibility, when compared with conventional sources. 相似文献
74.
Dhakshinamoorthy A Alvaro M Hwang YK Seo YK Corma A Garcia H 《Dalton transactions (Cambridge, England : 2003)》2011,40(40):10719-10724
Three MIL-100 (Fe) samples differing in average crystal size (from 60-70 to >400 nm) have been synthesized by microwave heating using three HF/Fe(3+) ratios. Oxidation of diphenylmethane with tert-butylhydroperoxide (TBHP) and thiophenol with oxygen are catalyzed by three MIL-100 (Fe) samples with similar reaction rates regardless of its average particle size. In contrast, the activity of the three MIL-100 (Fe) samples for the oxidation of bulky triphenylmethane by TBHP largely depends on the average crystal size of the sample: the smaller the average particle size, the larger the initial reaction rate of triphenylmethane oxidation. These results show that diffusion limitation takes place on MOF catalysis depending on the substrate size and provides indirect evidence that these reactions take place inside the intracrystalline space of the porous catalysts. 相似文献
75.
Montero R Conde AP Ovejas V Martínez R Castaño F Longarte A 《The Journal of chemical physics》2011,135(5):054308
The ultrafast relaxation of jet-cooled aniline was followed by time-resolved ionization, after excitation in the 294-234 interval. The studied range of energy covers the absorption of the two bright ππ? excitations, S(1) and S(3), and the almost dark S(2) (πσ?) state. The employed probe wavelengths permit to identify different ultrafast time constants related with the coupling of the involved electronic surfaces. A τ(1) = 165 ± 30 fs lifetime is attributed to dynamics along the S(2) (πσ?) repulsive surface. Other relaxation channels as the S(1)→S(0) and S(3)→S(1) internal conversion are also identified and characterized. The work provides a general view of the photophysics of aniline, particularly regarding the role of the πσ? state. This state appears as minor dissipation process due to the ineffective coupling with the bright S(1) and S(3) states, being the S(1)→S(0) internal conversion the main non-radiative process in the full studied energy range. Additionally, the influence of the off-resonance adiabatic excitation of higher energy electronic states, particularly S(3), is also observed and discussed. 相似文献
76.
Muñoz-Castro A 《The journal of physical chemistry. A》2011,115(39):10789-10794
Relativistic density functional calculations were carried out on several nickel toroid mercaptides of the general formula [Ni(μ-SR)(2)](n), with the aim to characterize and analyze their stability and magnetic response properties, in order to gain more insights into their stabilization and size-dependent behavior. The Ni-ligand interaction has been studied by means projected density of states and energy decomposition analysis, which denotes its stabilizing character. The graphical representation of the response to an external magnetic field is applied for the very first time taking into account the spin-orbit term. This map allows one to clearly characterize the magnetic behavior inside and in the closeness of the toroid structure showing the prescence of paratropic ring currents inside the Ni(n) ring, and by contrast, diatropic currents confined in each Ni(2)S(2) motif denoting an aromatic behavior (in terms of magnetic criteria). The calculated data suggests that the Ni(2)S(2) moiety can be regarded as a stable constructing block, which can afford several toroid structures of different nuclearities in agreement with that reported in the experimental literature. In addition, the effects of the relativistic treatment over the magnetic response properties on these lighter compounds are denoted by comparing nonrelativistic, scalar relativistic, and scalar plus spin-orbit relativistic treatments, showing their acting, although nonpronunced, role. 相似文献
77.
78.
We propose a general theory of the spin-transfer effects that occur when current flows through inhomogeneous magnetic systems. Our theory does not rest on an appeal to conservation of total spin, can assess whether or not current-induced magnetization precession and switching in a particular geometry will occur coherently, and can estimate the efficacy of spin-transfer when spin-orbit interactions are present. We illustrate our theory by applying it to a toy-model twodimensional-electron-gas ferromagnet with Rashba spin-orbit interactions. 相似文献
79.
Alvaro Valencia Sergio Botto Juan Sordo Marcelo Galvez Lautaro Badilla 《国际流体数值方法杂志》2007,53(5):793-809
Haemodynamics plays an important role in the progression and rupture of cerebral aneurysms. The temporal and spatial variations of the wall shear stress in the aneurysmal sac are hypothesized to be correlated with its growth and rupture. In addition, the assessment of the velocity field in the aneurysm dome and neck is important for the correct placement of endovascular coils. This work describes the flow dynamics in patient‐specific models of saccular aneurysms of different sizes located in the ophthalmic artery. The models were obtained from three‐dimensional rotational angiography image data and blood flow dynamics was studied under physiologically representative waveform of inflow. The three‐dimensional continuity and momentum equations for unsteady laminar flow were solved with commercial software using nonstructured fine grid sizes. The intra‐aneurysmal flows show complex vortex structures that change during one pulsatile cycle. A relation between the aneurysm aspect ratio and the mean wall shear stress on the aneurysmal sac is showed. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
80.
Jaime Rodríguez André Ferraz Raquel F. P. Nogueira Irene Ferrer Elisa Esposito Nelson Durán 《Applied biochemistry and biotechnology》1997,62(2-3):233-242
The lignin biodegradation process has an important role in the carbon cycle of the biosphere. The study of this natural process
has developed mainly with the use of basidiomycetes in laboratory investigations. This has been a logical approach since most
of the microorganisms involved in lignocellulosic degradation belong to this class of fungi. However, other microorganisms
such as ascomycetes and also some bacteria, are involved in the lignin decaying process. This work focuses on lignin biodegradation
by a microorganism belonging to the ascomycete class,Chrysonilia sitophila. Lignin peroxidase production and characterization, mechanisms of lignin degradation (lignin model compounds and lignin in
wood matrix) and biosynthesis of veratryl alcohol are outstanding. Applications of C.sitophila for effluent treatment, wood biodegradation and single-cell protein production are also discussed. 相似文献