Journal of Physical and Theoretical Chemistry
Volume:5 Issue: 4, Winter 2009

This paper investigates the mechanism of water transportation through aquaporin-4(AQP4) of ratbrain cells by means of molecular dynamics simulation with CHARMM software. The AQP4 wasembedded into a bilayer made of Dimystroilphosphatylcholine (DMPC). The results illustrate thatwater molecules move through AQP4's channel with change of orientation of oxygen of eachwater molecule.

Interaction of meso — tetrakis (p-sulphonato phenyl) porphyrin (hereafter abbreviated to TSPP)with Na+ has been examined using HF level of theory with 6-31G* basis set. Counterpoise (CP)correction has been used to show the extent of the basis set superposition error (BSSE) on thepotential energy curves. The numbers of Na+ have a significant effect on the calculated potentialenergy curve (including position, depth, and width of the potential well).

Metal—Polyaniline nanocomposites such as Platinum-Polyaniline nanocomposite is prepared by insitu oxidative polymerization of aniline and reduction of Pt+4 ions into Pt nanoparticles. Thepolymerization of aniline was carried out in the presence of 1(2PtCN6 [Potassium Hexa CyanoPlatinate (IV)] as oxidizing agent. During the reaction aniline monomers undergo oxidation andform polyaniline (PANT) whereas the reduction of [PtCN6]-2 ions result the formation of Ptnanoparticles. Nano-sized Pt particles were prepared by controlled reduction of Platinum precursorin micro emulsion medium, stabilized with the anionic surfactant (AOT). Micro emulsion solutionacts as both emulsifier and dopant to obtain stable nanocomposite. PANI-AOT-Pt nanocompositeis characterized by FT-IR spectroscopy and scanning microelectronic microscopy (SEM).

The determination of gyration radius is a strong research for configuration of a Macromolecule. Italso reflects molecular compactness shape. In this work, to characterize the behavior of theprotein, we observe quantities such as the radius of gyration and the average energy. We studiedthe changes of these factors as a function of temperature for Acetylcholine receptor protein in gasphase with native structure, - helix and - sheet conformation by Monte Carlo, Molecular andlangevin dynamics simulations. It was found when the temperature is increased the kinetic energyis increased too, and its diagram is linear. Monte Carlo simulation is a stochastic method andtherefore, is the best method to evaluate gyration radius. Considering the gained values fromMonte Carlo, Molecular and langeving dynamics simulations for - helix conformation and littledeviations from the experimental value, it can be understood that the second structure of thisprotein is the kind in which - helix is more. All the calculations were carried out usingHyperchem 8.0 program package. Gyration radius is calculated using VMD 1.8.6 Software.

In this research, a PVC membrane electrode for Manganese (II) ions based on N-(2-Picolinamidoethyl)Picolinamide as neutral carrier was prepared. The electrode exhibits a Nemstian responseover Mn(II) concentration range of (1.0 x10-5 t01.0 X 10-1M) with a slope of 29.3±0.5 mV perdecade of concentration with a working pH range of 4.0-9.0. It has a fast response time (<15s) andcan be used for at least two months without any considerable divergence in the potential. Theproposed sensor shows a fairly good discriminating ability towards Mn2+ ion in comparison tosome hard and soft metal ions. Selectivity coefficients determined by the matched potentialmethod (MPM). The electrode was applied to the determination of Manganese (II) ions in realsamples.

The oxidation of n-pentanol by tetramethylammonium fluorochromate in acidic solution wasstudied using spectrophotometric technique. The reaction was arranged to be under pseudo firstorderconditions respect to the oxidant. A Michaelis-Menten type kinetic was observed respect tothe substrate. The reaction is catalyzed by hydrogen ions. Dependences of the reaction rates ontemperature and different solvents have been studied. The solvent effect was analyzed usingKamlet-Taft's and Swain's multiparametric equations. Finally, a mechanism consistent with theobserved results has been proposed and discussed.

The interaction of biomolecules with carbon nanotubes (CNTs) has generated a great deal ofinterest in the past few years. The interaction between B-form single-strand DNA (ssDNA) andsingle-walled carbon nanotubes (SWCNTs) is a subject of intense current interest; however thereare a relatively small number of papers in the literature dealing with interaction of DNA andSWCNTs. In this work we investigate interaction of ssDNA with open-end of SWCNT; usingAMBER, MM+ and OPLS force fields in molecular mechanic (MM) method. We study effects ofincrease the molecular number of solvent on interaction of ssDNA with SWCNTs, using theseforce fields too. The interaction of ssDNA with open-end of SWCNT in water and ethanol havebeen calculated using density functional theory (DFT) at the theoretical level of B3LYP/6-31G (d,p) and have been made a comparison between dipole moment; energy and atomic charges invacuum; water and ethanol. Our results show that interaction of ssDNA with open-end of SWCNTcould be optimum in polar solvent.

Using the Solvent Evaporating and Atomic Emission Spectrophotometric methods, the solubilitiesof Li2CO3 were determined in various mixed- solvent "water + ethanol" with various mass percentof ethanol, and in the presence of NaNO3 in various molarities at 25.0°C . The results wereinterpreted in terms of mean ionic activity coefficient and ion association phenomenon.