Journal of Physical and Theoretical Chemistry
Volume:5 Issue: 3, Autumn 2008

Polycyclic aromatic hydrocarbons (PAHs) are a class of compounds consisting of more than twobenzene rings fused in a linear, angular, or clustered arrangement and do not contain hetero atomsor carry subsistent. PAHs originate from various sources. They are primarily formed byincomplete combustion of carbon-containing fuels such as wood, coal, diesel, fat, or tobacco. Thepresent study reports an investigation of the electronic structure of Pyrene by use of differentmodel chemistries. We also made a comparison between different model chemistries. Linearrelationship between the energy and Z-matrix of the structure were found. The energy diagramsvs. the number of primitive Gaussian wave functions and vs. distance matrix shows the energyvariations in model chemistries HF/6-31G*, HF/6-31++G**, MP2/6-31G, MP2/6-31++G**,BLYP/6-31G, BLYP/6-31++G**, B3LYP/6-31G and B3LYP6-31-HEG**, as well. High symmetryof the Pyrene molecules makes four regions in the study of the NMR shielding tensors. Theisotropic and anisotropic tensors of the Pyrene structure, calculated with different modelchemistries, too. The results show that only the C and D part of the Pyrene structure are affectedby the magnetic field.

The reaction mechanism between (H2C) and (7, 0), zigzag single-walled carbon nanotubes(ZSWCNTs) on two different orientation of C-C have been studied by semi empirical AM!method. The activation barriers of (H2C) adding to (7, 0) ZSWCNT are computed and compared.The effects of diameters of zigzag SWCNT on their binding energies were studied

Fe2+ ion-selective membrane sensor has been fabricated from polyvinyl chloride (PVC) matrixmembrane containing neutral carrier tetra phenyl porphyrin (TPP) ionophore. The addition ofsodium tetraphenylborate (NaTPB) and the plasticizer DBP has been found to substantiallyimprove the performance of the sensor. The best performance was obtained with the sensor havinga membrane of composition of TPP: NaTPB: DBP: PVC in the ratio 6:3:61:30 respectively. Thesensor shows a linear response over a wide concentration range of 1.0 x 10-6 to 1.0 x 10-2 M witha Nemstian slope of 29.4 ± 0.6 mV decade-1 and a detection limit of 9.6 x 10-7 M. It has aresponse time of <12 s and can be used for more than seven weeks without any measurabledivergences in its potentials. The proposed sensor could be used in a pH range of 3.0-5.0.Potentiometric selectivity coefficients determined by matched potential method (MPM) indicateexcellent selectivity for Fe2+ ion.

This radionuclide is almost exclusively produced from the decay of its parent 99Mo. 99mTc is themost available and important nuclide used as a diagnostic agent in nuclear medicine. To develop anewly practical 99mTc generator using ( n,y ) 99Mo, an inorganic polymer adsorbent has beendeveloped framed with oxygen-zirconium-chlorine bonds with a high adsorption of Mo, Thepolyzirconium adsorbent was named PZC ( poly zirconium chloride) which made clear that PZChas an ability and high performance as a practical adsorbent for 99mTc generator using ( n, y)99Mo. The amount of 99Mo adsorbed to PZC reached about 250mg/g PZC. 99mTc was elutedwith a small volume of saline solution in the yield of about 76.43 %. The breakthrough of 99Moin the elution of 99mTc was less than 0.015%.

Milk clotting enzyme (M CE) produced by: Rhizomucor miehei was purified and characterized.The enzyme was purified 220.29-fold with specific activity about 14444.2 U/mg protein byultrafiltration, ammonium sulfate fractionation, Sephacryl S-300 chromatography. The maximumenzyme activity was at 65°C.The milk clotting activity was decreased steadily as pH is increased and indicated maximumactivity at pH 5.3.Ferthermore we did some computational methods for understanding the changesin energy.

Stoichiometric tetragonal Bal-xSrxTiO3 (x = 0.23) nanopowders were prepared by stearic acid gel(SAG) method using barium stearate, strontium stearate, tetrabutyl titanate as Ba, Sr, Ti sourcesand stearic acid as complexing reagent. Thermal analysis including differential thermogravimetric(DTG) and TG, Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD) andtransmission electron microscopy (TEM) were used to characterize the crystallization process,particle size and morphology of the calcined powders. The results indicated that single- phasetetragonal and well crystallized Bal-xSrxTiO3 (x = 0.23) nanopowders with particle size around45 nm were formed after calcining the dried gel at 700 °C for 2 h.PACS code: 81,07Wx

Medicinal chemistry depends on many other disciplines ranging from organic chemistry andpharmacology to computational chemistry. Typically medicinal chemists use the moststraightforward ways to prepare compounds. The validation of any design project comes from thebiological testing.Studies of the binding site of vinblastine by a single cross—linking experiment identified it asbeing between residues 175-213 in 13—tubulin.These polypeptide residues are in the region oflateral or longitudinal contacts of protofilaments on the microtubule in the absence of a ligand. Inthe presence of vinblastine or other active vinca alkaloids a kink is formed that disturbs normalmicrotubule formation and favors depolymerization.In an effort to understand the conformational preferences that may be attributed to stereoelectroniceffects, a number of computational chemistry studies carried out. Molecular mechanics, MonteCarlo, Molecular Dynamics and Langevin calculations using the AMBER force field performedon vinblastine .These results show the minimized structure of vinblastine, calculated potentialenergy for important dihedral angles, and the effect of temperature on geometry of optimizedstructure

In this research, this possibility was investigated the relative stablilty geometry and bindingenergies of the hydrogen bonds of Molybdate-Phosphonic Acid (MPA) complex in gas phase onthe basis of result of ab initio and DFT calculations. Three DFT methods have been applied forcalculations are B3LYP, BP86 and B3PW91 that have been studied in two series of basis sets:D95** and 6-31+G(d,p) for hydrogen and oxygen atoms; LANL2DZ for Mo and Phosphorus inwhich the basis set superposition error correction is also considered. At the B3LYP theory level, itis found that the best results for energetics and geometry of the ground state was obtained. TheBSSE begins to converge for all of Methods/basis sets. For hydrogen-bonded systems, most levelsof theory seem to give reasonable estimates of the known binding energies, but here, the bindingenergies after correction for BSSE are rather stable.