dft calculations were applied to evaluate the electronic and magnetic properties of zigzag bc2nnanotubes based on the 13c, 15n, and 11b nmr parameters and natural charge analysis. weconsidered three types of zigzag nanotubes, zz-1, zz-2, and zz-3 (n, 0) with n = 8, 12, and 14. theobtained results indicated the divisions of the electrostatic environments around c nuclei into a fewlayers, consist...

we have evaluated the nmr shielding tensors for a:t,g:c,a:u in watson-crick, and u-quartet. we have computed nmr shielding tensors at b31yp level by using 6-31g(d) basis set. we have compute anisotropy and asymmetry in a:t,g:c,a:u and u-quartet. the nmr shielding tensors were calculated using the giao method. the natural bonding orbital analysis (nbo) were performed. nbo calculation have been ...

the ion-pair association constant values, related to the reaction +  were determined by means of the nmr spectroscopy. the values of the thermodynamic functions of the ion pairing process were calculated on the basis of the nmr results. in addition, the association entropy was found to be dependent on the temperature. comparing the experimental data and the fuoss theory it is found that  ion-pa...

some innovative solutions are proposed to the problem of the unavoidable physical migration of antioxidants from plastic films for packaging, in order to minimize the consequent undesirable effect of food contamination. in previous exploratory tests, phenolic antioxidant co-units were achieved and incorporated into polyethylene chain and now the work is extended to create new families of polyme...

the thermo-oxidative degradation of two viscous liquid resins of 1,2- poly-butadiene  (1,2-pbd) and 1,4- polybutadiene  (1,4-pbd) have been studied by differential scanning calorimetry (dsc) and thermogravimetry analy-sis  (tga). to  study  further,  the  effect of flm  thickness on oxidation kinetics was periodically studied by tracing the weight of the samples to make comparison with dsc resu...

condensation of aromatic aldehydes with benzoyl acetone under specified conditions yieldedtwo series of polycarbonyl compounds in which the keto group is attached to olefinic linkage.spectral and analytical data revealed the formation of an unsaturated triketone from pyridine-3-carbaldehyde and unsaturated diketone from furfural, salicylaldehyde and 2-hydroxynaphthaldehyde. analytical, ir, 1h n...

The 5'-end of the P1 promoter of the B-cell lymphoma-2 (bcl-2) gene contains a highly guaninecytosine-rich region, which has a role in the regulation of bcl-2 transcription. Whereas the guanine-rich region has been the focus of recent studies, little attention has been paid to the cytosine-rich strand. Here we examine the structural transitions of the cytosine-rich sequence by means of acid-bas...

A generalized 2D correlation NMR (GEN2D-NMR) scheme capable of substantially reducing the experimental time for two-dimensional correlation NMR experiments is described. The experimental time used in GEN2D-NMR is shortened to less than one-tenth of that required in traditional double Fourier transform 2D-NMR (FT2D-NMR) for a 13C-13C spin diffusion experiment for Nephila edulis spider threads. E...