an ab initio and density functional theory (dft) study about conformational analysis of tripeptide model hco−gly−l−ile−gly−nh2 is presented. the tripeptide was scanned about initial, central, and final residues, separately while for every scanning procedure the two other residues had been kept in the β conformation and side chain (sc) dihedral angles were maintained on the gauche− (g‾) state (χ...

ab initio calculations at hf/6-31g* level of theory for geometry optimization and mp2/6-31g*//hf/6-31g*for total energy calculation are reported for z-cyclooctene (1). the most favorable conformation of 1 is theunsymmetric boat-chair (1-bc) geometry. potential energy profiles for two different boat-chair/boat-chairinterconversion processes were calculated. the process via a chair transition sta...

the thermodynamic functions such as enthalpy (h), gibbs free energy (g) and entropy (s) of serineand threonine amino acids were theoretically studied at different condition (solvents andtemperatures) by using gussian o3, software. first, the structural optimization of isolated serine andthreonine were done in the gas phase by using the hartree-fock (hf) level of theory with 3-21g, 6-31g and 6-3...

in this paper,the molecular geometry for three tautomers of uracil and four tautomers of cytosine has been analyzed. vibrational ir spectra of the tautomers were   investigated at hf and b3lyp level using the ab initio 6-31g* and lanl2dz basis sets from the program package gaussian 98 (a.7 public domain version). the physico-chemical and biochemical properties of uracil and cytosine are one of...

maharlu saline lake is located in the sw of iran. to assess the environmental pollution of thelake, the total concentrations of as, cr, co, cu, cd, pb, zn, ni, fe, and mn were determined in the surfacesediments and water of the lake. as and cr were not detected in the water samples, however, the meanconcentrations of other dissolved metals in maharlu lake water were 0.28 mg/l for cu, 0.28 μg/l ...

objective(s): first principles calculations were performed to study four multiple sclerosis drugs namely, ampyra, fingolimod, mitoxantrone and eliprodil in gas and liquid phases using density functional theory (dft). computational chemistry simulations were carried out to compare calculated quantum chemical parameters for ampyra, fingolimod, mitoxantrone and eliprodil. materials and methods: al...

ab initio calculations were employed to investigate nitrogen inversion as a configuration change that can supply an infinitely useful switchable control mechanism for some complex systems. in this paper, design of a new artificial molecular nanohinge is discussed based on nitrogen inversion in which reciprocating motion of substituent in effect of inversion phenomenon, led to an open–close moti...

background: monte carlo (mc) modeling of a linear accelerator is a prerequisite for monte carlo dose calculations in external beam radiotherapy. in this study, a simple and efficient model was developed for elekta sl-25 linear accelerator using mcnp4c monte carlo code materials and methods: the head of elekta sl-25 linac was simulated for 6 and 18 mv photon beams using mcnp4c mc code. energy sp...

in this work facile sol-gel (pechni) method has been successfully established to synthesize zn4b6o13 nanocrystals which have cubic crystals with lattice parameter: a =7.48 a. the structure and morphology of the obtained material were studied by x-ray diffraction (xrd), infrared spectra (ir), scanning electron microscopy (sem) and photoluminescence analysis. the experimental results show a band ...