nowadays nmr spectroscopy becomes a powerful tool in chemistry because of the nmr chemical shifts. hartree–fock theory and the gauge-including atomic orbital (giao) methods are used in the calculation of 29si nmr chemical shifts of various silicate species in the silicate solution as initial components for zeolite synthesis both in gas and solution phase. calculations have been performed at geo...

the chemical composition, ruminal degradability parameters, ruminal and post ruminal digestibility of saffron residues were determined using in situ and in vitro (gas production) methods. the harvested residues at late vegetative phase were compared with the residues harvested at the early dormant phase. the results showed that ndf and adf concentration of harvested residues at early dormant ph...

a combined gas chromatography–mass spectrometry (gc–ms) with headspace solid-phase microextraction (hs-spme) method has been employed for the analysis of the flavor volatiles of some iranian rice cultivars (domsiah, deylamani, hashemi, shirodi and tarom). the samples were grown in different cities of mazandaran province. the sampling procedure and chromatographic conditions were same for all sa...

this paper is a density functional theory (dft) calculation of intramolecular proton transfer (ipt) in 6-hydroxypicolinic acid (6hpa, 6-hydroxypyridine-2-carboxylic acid) tautomeric forms. the transition state for the enol-to-keto transition is reported in the gas phase and in four different solvents. the planar and non-planar dimer forms of 6hpa keto and enol, respectively, were also studied i...

This paper is a density functional theory (DFT) calculation of intramolecular proton transfer (IPT) in 6-hydroxypicolinic acid (6HPA, 6-hydroxypyridine-2-carboxylic acid) tautomeric forms. The transition state for the enol-to-keto transition is reported in the gas phase and in four different solvents. The planar and non-planar dimer forms of 6HPA keto and enol, respectively, were also studied i...

In this research, the interaction of pyrimidine molecule with pristine B12N12 nanocluster is studied in different phases to understand the effect of environment on the electronic properties of the designated adsorption complexes. To this end, the pyrimidine adsorption over B12N12 in the gas phase and water medium is investigated using density functional theory (DFT) at the B97D/6-31+G(d,p) leve...

A fragment of Histidine rich protein II (HRP II 215-236) was investigated by 14N and 17O electric field gradient, EFG, tensor calculations using DFT. This study is intended to explore the differences between 310-helix and α-helix of HRPII both in the gas phase and in solution. To achieve the aims, the 17O and 14N NQR parameters of a fragment of HRPII (215-236) for both structures are calculated...

This study aimed to construct the hydrate three-phase equilibrium curves for two typical Iranian gas reservoir samples using a high-pressure visual cell. To do so, complete analysis of the reservoir fluids was obtained by different techniques of composition analysis i.e. gas chromatography (GC) and detailed hydrocarbon analysis (DHA). Using high-pressure visual cell the hydrate phase equili...