239 research outputs found

    ELECTRON MICROSCOPIC STUDY OF THE AORTIC INTIMA OF DIABETIC RATS

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    The R–7 Dispersion Interaction in the General Effective Fragment Potential Method

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    The R–7 term (E7) in the dispersion expansion is developed in the framework of the general effective fragment potential (EFP2) method, formulated with the dynamic anisotropic Cartesian polarizability tensors over the imaginary frequency range. The E7 formulation is presented in terms of both the total molecular polarizability and the localized molecular orbital (LMO) contributions. An origin transformation from the center of mass to the LMO centroids is incorporated for the computation of the LMO dipole–quadrupole polarizability. The two forms considered for the damping function for the R–7 dispersion interaction, the overlap-based and Tang–Toennies damping functions, are extensions of the existing damping functions for theR–6 term in the dispersion expansion. The R–7 dispersion interaction is highly orientation dependent: it can be either attractive or repulsive, and its magnitude can change substantially as the relative orientation of two interacting molecules changes. Although the R–7 dispersion energy rotationally averages to zero, it may be significant for systems in which rotational averaging does not occur, such as rotationally rigid molecular systems as in molecular solids or constrained surface reactions

    POSSIBILITIES FOR INCREASING THE YIELDS AFTER PRE-SOWING ELECTRIC TREATMENT OF WHEAT AND MAIZE SEEDS

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    Following many years of research, it has been determined that for the environmentally friendly stimulation of the growth of plants and increase of their yields, it is necessary to apply pre-sowing electromagnetic treatment to the seeds of these plants.A study has been carried out of the impact of the pre-sowing electromagnetic treatment of the seeds of different Bulgarian wheat varieties and of maize hybrids provided by Bulgarian producers and by the companies Pioneer-USA and the French Maisadour Semences.At certain values of the controllable factors of the pre-sowing treatment, the following results have been achieved: an increase of (9...20)% in wheat yields as compared to the control batch, and an increase in the length of the maize ears, a higher number of leaves and a higher number of kernel rows in an ear, a higher number of kernels in a row, and yields increased by (5...21)% as compared to the control batch.Following many years of research, it has been determined that for the environmentally friendly stimulation of the growth of plants and increase of their yields, it is necessary to apply pre-sowing electromagnetic treatment to the seeds of these plants.A study has been carried out of the impact of the pre-sowing electromagnetic treatment of the seeds of different Bulgarian wheat varieties and of maize hybrids provided by Bulgarian producers and by the companies Pioneer-USA and the French Maisadour Semences.At certain values of the controllable factors of the pre-sowing treatment, the following results have been achieved: an increase of (9...20)% in wheat yields as compared to the control batch, and an increase in the length of the maize ears, a higher number of leaves and a higher number of kernel rows in an ear, a higher number of kernels in a row, and yields increased by (5...21)% as compared to the control batch

    Centralized Rate Control Mechanism for Cellular-Based Vehicular Networks

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    Benchmarking the Performance of Time-Dependent Density Functional Methods

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    The performance of 24 density functionals, including 14 meta-generalized gradient approximation (mGGA) functionals, is assessed for the calculation of vertical excitation energies against an experimental benchmark set comprising 14 small- to medium-sized compounds with 101 total excited states. The experimental benchmark set consists of singlet, triplet, valence, and Rydbergexcited states. The global-hybrid (GH) version of the Perdew-Burke-Ernzerhoff GGA density functional (PBE0) is found to offer the best overall performance with a mean absolute error (MAE) of 0.28 eV. The GH-mGGA Minnesota 2006 density functional with 54% Hartree-Fock exchange (M06-2X) gives a lower MAE of 0.26 eV, but this functional encounters some convergence problems in the ground state. The local density approximation functional consisting of the Slater exchange and Volk-Wilk-Nusair correlation functional (SVWN) outperformed all non-GH GGAs tested. The best pure density functional performance is obtained with the local version of the Minnesota 2006 mGGA density functional (M06-L) with an MAE of 0.41 eV

    Solvent Effects on Optical Properties of Molecules: A Combined Time-Dependent Density Functional Theory/Effective Fragment Potential Approach

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    A quantum mechanics/molecular mechanics (QM/MM) type of scheme is employed to calculate the solvent-induced shifts of molecular electronic excitations. The effective fragment potential (EFP) method was used for the classical potential. Since EFP has a density dependent functional form, in contrast with most other MM potentials, time-dependent density functional theory (TDDFT) has been modified to combine TDDFT with EFP. This new method is then used to perform a hybrid QM/MM molecular dynamics simulation to generate a simulated spectrum of the n→π∗ vertical excitation energy of acetone in vacuum and with 100 water molecules. The calculated watersolvent effect on the vertical excitation energy exhibits a blueshift of the n→π∗ vertical excitation energy in acetone (Δω1=0.211 eV), which is in good agreement with the experimental blueshift

    Nonlinear Response Time-Dependent Density Functional Theory Combined with the Effective Fragment Potential Method

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    This work presents an extension of the linear response TDDFT/EFP method to the nonlinear-response regime together with the implementation of nonlinear-response TDDFT/EFP in the quantum-chemistry computer package GAMESS. Included in the new method is the ability to calculate the two-photon absorption cross section and to incorporate solvent effects via the EFP method. The nonlinear-response TDDFT/EFP method is able to make correct qualitative predictions for both gas phase values and aqueous solvent shifts of several important nonlinear properties
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