in this study, the effect of the secondary structure of the protein on the acid strength of three structures of random (r), alpha helix (α) and beta sheet (b) were investigated theoretically. these structures are related to the cationic amino acids of histidine and lysine in the polypeptide chain of eight-glycine residue. computational methods at the hf, b3lyp, x3lyp and m05-2x levels in the ga...

objective: excessive weight in children is a major public health concern. the intake of refined carbohydrates, especially sugars and the prevalence of dental caries are well documented in the literature. the purpose of this study was to investigate the relationship between dental caries and bmi in elementary school children. materials and methods: the sampling technique used in the present stud...

one of the most common signals used for achieving high range resolution in radar is stepped-frequency signals. when a target is stationary in these radars, dft (discrete fourier transform) based processing is used to attain high range resolution profile (hrrp). however, in the case of moving target, due to spreading of the echo signal spectrum, dft based processing is not optimal and decreases ...

using hartree–fock (hf) and ِِdensity functional theory (dft) calculations the thermodynamic properties such as thermal energy , , thermal enthalpy , , thermal entropy , , thermal gibbs free energy , , heat capacity ,cv, and molecular structures of several species involving in keto↔enol tautomerism related to acetaldehyde (a), 5,5-dimethyl-1,3-cyclohexanedione (dimedone) and  acetylacetone (aa) h...

using a time-dependent-density functional theory (td-dft), configuration interaction singles (cis) and zerner’s intermediate neglect of differential overlap (zindo) methods, we have investigated the uv-visible spectra of one new intramolecular cyclization at before and after intramolecular attack. all structures were optimized at the b3lyp/6-311++g** level while uv-visible parameters were calcul...

Many existing results on the analysis of OFDM systems are based on an analog representation. The actual implementation of OFDM transmitters typically consists of a discrete DFT matrix and a digital-to-analog (DAC) converter. In this paper, we show that the analog representation admits the implementation of a DFT matrix followed by a DAC converter only in special cases. Necessary and sufficient ...

Determining orthonormal eigenvectors of the DFT matrix, which is closer to the samples of Hermite-Gaussian functions, is crucial in the definition of the discrete fractional Fourier transform. In this work, we disclose eigenvectors of the DFT matrix inspired by the ideas behind bilinear transform. The bilinear transform maps the analog space to the discrete sample space. As jω in the analog s-d...

The conversion of ethanol to ethylene, which is one of the most important feed stocks for the petrochemical industry, is of particular commercial interest. Two mechanisms, stepwise and concerted, of the ethanol dehydration to ethylene in the presence of water have been investigated by the ONIOM model (14T/120T) with B3LYP/6-31g(d,p):UFF method. In the stepwise mechanism, the coadsorbed water as...