Journal of Physical and Theoretical Chemistry
Volume:7 Issue: 3, Autumn 2010

The lack of complete understanding of the substrate effects on carbon nanotubes (CNTs) growth poses a lot oftechnical challenges. Here, we report the direct growth of nanostructures such as the CNTs on stainless steel 304and brass substrates using thermal chemical vapor deposition (TCVD) process with C2H2 gas as carbon sourceand hydrogen as supporting gas mixed in Ar gas flow. We used an especial etching of substrates. The catalystsconsist of a thin layer of Cu deposited on substrates. Morphology and structural information about preparedCNTs were provided by scanning electron microscopy (SEM). Results showed that some nanostructures such assingle and multi walled carbon nanotubes (SWCNTs and MWCNTs), bundle (70-80 nm), nano wire (80-100nm) and amorphous carbon were formed on stainless steel 304 as substrate. Moreover, different kind of carbonnanotubes such as MWCNTs (30-50 tun), nano crystalline diamond (10-30 nm), amorphous carbon, roped (70-80 nm) structures with different sizes grew on the brass substrate as well. In conclusion, we suggest thatstainless steel 304 and brass can be replaced with Si/Si02 as substrate in practical applications.

Serum Albumin is the most abundant protein in blood plasma. Its two major roles are maintaining osmoticpressure and depositing and transporting compounds. In this paper Albumin-Ethanol/Water solutionssimulations are carried out by three techniques including Monte Carlo (MC), Molecular Dynamic (MD) andLangevin Dynamic (LD) simulations in aqueous solutions. Investigation the energy changes with time andtemperature (between 273K to 303K) showed that MC technique is not suitable for macromolecule simulations.Also by comparing optimized energy in Albumin-water system and Albumin-Ethanol systems, it isdistinguished that Albumin-Ethanol systems are more stable. So Ethanol can poison Albumin. Also the heatcapacity of these systems is evaluated and it is shown that if the molecular mass of solvent increases, the valueof heat capacity becomes more.

A theoretical study of the kinetics and mechanism of second-order intermolecular C.) cloadd it ion of 2-Ethyny1-2,3-Dihydrofurane and Phenyl Azide was performed using DFT method at 101.111 le) cl of theory with 6-31 PrEG(d,p) basis set at 298.15K. Equilibrium molecular geometries and harmonic ) ihrational frequencies ofthe reactants, transition state, and product were calculated. The kinetic and thermod. mimic parameters of thereaction were investigated. These calculations indicated that the reaction proceeds through a synchronousconcerted mechanism.

The electronic and structural properties of pristine and carbon doped (C-doped) boron nitride nano-ribbons(BNNRs) have been studied employing density functional theory (DFT) calculations. Total energies, gapenergies, dipole moments, and quadrupole coupling constants (qcc) have been calculated in the optimizedstructures of the investigated BNNRs. The results indicated that the stability and gap energy of the BNNR weredecreased whereas the polarizabilty was increased because in the C-doped structure. The calculated qcc valuesindicated that the electronic properties of the nitrogen atoms were influenced because of the C-doping more thanthe boron atoms.

Thermal denaturation of a-Lactalbumin in the absence and presence of various concentrations of sucrose,sorbitol, glucose and galactose as sugar osmolytes were measured by monitoring changes in the absorptions thatcarried out in a Lambd 35 UV-Vis double beam spectrophotometer at pH 6.0. These measurements gave valuesof T., (midpoint of denaturation), AH., (enthalpy change at T.), and ACp (constant-pressure heat capacitychange) under a given solvent condition. Using these values of AH., T., and AC, AGD° (Gibbs energy change),was determined at a given concentration of each sugar. It has been observed that each sugar stabilizes the a-Lactalbumin in terms of T,„ and AGD°. The temperature that corresponds to maximum protein stability, Ts, isincreased in the presence of these osmolytes. The same trend was also observed for TM, the temperaturecorresponding to zero enthalpy change of denaturation

In the present work, we have investigated the sorption efficiency of the treated activated carbon from walnut shell(ACW) towards Direct Red 81 (DR81) and Direct Blue 71 (DB71) for the removal from aqueous solution. Thesorption study of ACW at the solid-liquid interface was investigated using kinetic, sorption isotherms, pH effectand amount of adsorbent. Experimental data were analyzed by Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) isotherms. Langmuir isotherm model (R2 =0.9664 and R2 =0.9484) fitted the equilibrium datathe best other isotherms for DR81 and DB7I. According to the results maximum adsorption occurred in acidic pH.The results showed that the sorption processes of DR81 and DB71 on ACW are in good agreement with pseudosecondorder kinetic. Maximum amount of adsorbent for adsorption of mentioned dyes was 1 gr.

In this work, we investigated the stability of Molybdate-Phosphonic Acid (MPA) complex by density functionaltheory (DFT) computations in six solvents with the dielectric constant ranging from 1.92 to 10.36. The methodsare used for calculations are B3LYP and B3PW9 I that have been studied in two series of basis sets: D95nand6-31+G (d,p) for hydrogen and oxygen atoms; LANL2DZ for Mo and Phosphorus. Considering the effect ofsolvent, using PCM solvent model, the stability of MPA complex when passing to higher dielectric constants iscalculated. Predicted geometry and relative stability are discussed. Equilibrium geometry in the groundelectronic state energy has been calculated for 1:1 complex. The best results for energetic and geometricalground state in different of used solvents were obtained with Becke3LYP calculations. An increasingstabilization of MPA when increasing the dielectric constant in a continuum solvent model.

In this study the application of ZnO nanoparticles to UV photocatalytic degradation of nonionic surfactantTriton X-100 in aqueous media was investigated. The affecting factors on the photodegradation such as TritonX-100 initial concentration, nanocatalyst weight, pH, temperature and other parameters were studied anddescribed in details. The degradation rate was found to be strongly influenced by all the above parameters .Theoptimized conditions for maximum amount of degradation were also determined Results showed that thephotocatalytic degradation process using UV light as an irradiation source, and Nanoparticles of ZnO as aphotocatalyst, was applicable for the degradation of Triton X-100 in aqueous solution and wastewater samples.

Density functional theory calculations (DFT), as well as hybrid methods (B3LYP) for Bi8N18-[CoF6]3- complexhave been carried out to study the non-bonded interaction. The geometry of the 1313N18 has been optimized atB3LYP method with EPR-II basis set and geometry of the [CoF6]3 have been optimized at B3LYP method withDe12-TZVP basis set and Stuttgart RSC 1997 Effective Core Potential. The electromagnetic interactions of the[CoF6]3- molecule embedded in the B13N18 nano ring have been investigated at B3LYP and total atomic charges,spin densities, dipole moment and isotropic Fermi coupling constants parameters in different loops and bonds ofthe B15N18-[CoF613- system have been calculated. Also NBO analysis such as electronic delocalization betweendonor and acceptor bonds has been studied by DFT method. Then we have been investigated the lowestunoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) for the lowestenergy have been derived to estimate the structural stability of the Bi8N18-[CoF6]3- system. The Gaussianquantum chemistry package is used for all calculations.

Highly sinterable alumina nano-powders have been synthesized by a sol-gel combustion method with glycine asfuel. The preparation involved the thermal decomposition of a chelating agent (fuel)-nitrate gel and theformation of amorphous precursors. The nanopowders calcined at 1100°C were characterized by X-ray powderdiffraction (XRD) and Scanning Electron Microscopy (SEM). It was found that the chelating agent and fuelused had a significant influence on the average grain size of a-A1203 nanopowder. The rate of combustionreaction between chelating agent (fuel) and nitrate was responsible for the growth of the grain.