Theoretical and Experimental Study on the Adsorption and Desorption of Methane by Granular Activated Carbon at 25 ℃

A theoretical and experimental study was conducted to accurately determine the amount of adsorption and desorption of methane by various Granular Activated Carbon(GAC)under different physical conditions.To carry out the experiments,the volumetric method was used up to 500 psia at constant temperature of 25℃.In these experiments,adsorption as well as desorption capacities of four different GAC in the adsorption of methane,the major constituent of natural gas,at various equilibrium pressures and a constant temperature were studied.Also,various adsorption isotherm models were used to model the experimental data collected from the experiments.The accuracy of the results obtained from the adsorption isotherm models was compared and the values for the regressed parameters were reported.The results shows that the physical characteristics of activated carbons such as BET surface area,micropore volume,packing density,and pore size distribution play an important role in the amount of methane to be adsorbed and desorbed.     

Three-component synthesis of N-sulfonylformamidines in the presence of magnetic cellulose supported N-heterocyclic carbene-copper complex,as an efficient heterogeneous nanocatalyst

A cellulose based magnetic nanocomposite possessing NHC-Cu Complex has been synthesized and characterized. It was then applied as a highly active catalyst in one-pot three-component reaction of sulfonyl azides, secondary amines and triethylamine to afford N-sulfonylformamidines. Copper catalyzed oxidative transformation of C-N bond of triethylamine is a key step to give desired products. In contrast with the good reactivity of the conventional secondary amines, aromatic amines and NH containing heteroaromatics had no activity in these reactions. Moreover, the used nanocatalyst which could be recovered by external magnet, showed reasonable catalytic activity for several times.     

Domino 'Staudinger-aza-Wittig-1,5-phosphonium-rearrangement-fragmentation' reactions of 1-azido-2-hydroxy-4,6-dioxohexanes

The domino 'Staudinger-aza-Wittig-1,5-phosphonium-rearrangement-fragmentation' reaction of 1-azido-2-hydroxy-4,6-dioxohexanes allows a convenient synthesis of functionalized 1-acetamido-2-alkylidenecyclopentanes.     

Theoretical calculation of excitonic binding energies and optical absorption spectra for Armchair graphene nanoribbons

In this paper the excitons of armchair graphene nanoribbons with layers of different width and thickness have been investigated. In this investigation, the band structure and energy gap of armchair graphene nanoribbons have been calculated using a tight-binding model including edge deformation effects (all edge atoms have been passivated with hydrogen atoms). Also, by calculating the conductance in armchair graphene nanoribbons (A-GNRs) optical absorption of armchair graphene nanoribbon in the single-electron approximation has been obtained. Finally, the binding energy of excitons in armchair graphene nanoribbons has been calculated using the Wannier model, Hartree-Fock approximation and the Bethe-Salpeter equation.     

Binary and ternary blends of high‐density polyethylene with poly(ethylene terephthalate) and polystyrene based on recycled materials

Binary blends of recycled high‐density polyethylene (R‐HDPE) with poly(ethylene terephthalate) (R‐PET) and recycled polystyrene (R‐PS), as well as the ternary blends, i.e. R‐HDPE/R‐PET/R‐PS, with varying amounts of the constituents were prepared by twin screw extruder. The mechanical, rheological, thermal, and scanning electron microscopy (SEM) analyses were utilized to characterize the samples. The results revealed that both R‐HDPE/R‐PET and R‐HDPE/R‐PS blends show phase inversion but at different compositions. The R‐PET was found to have much higher influence on the properties enhancement of the R‐HDPE compared to R‐PS, but at the phase inverted situation, a significant loss in the tensile strength of R‐HDPE/R‐PET blend was observed due to the weak interaction at this morphological state. However, the ternary blends with higher loading of second phase, namely greater than 50 wt% of R‐PET+R‐PS, demonstrated better mechanical properties than the binary blends with the same content of either R‐PET or R‐PS. Copyright © 2009 John Wiley & Sons, Ltd.     

Size-dependent dynamic pull-in instability of hydrostatically and electrostatically actuated circular microplates

In the present study, the dynamic pull-in instability and free vibration of circular microplates subjected to combined hydrostatic and electrostatic forces are investigated. To take size effects into account, the strain gradient elasticity theory is incorporated into the Kirchhoff plate theory to develop a nonclassical plate model including three internal material length scale parameters. By using Hamilton’s principle, the higher-order governing equation and the corresponding boundary conditions are obtained. Afterward, a generalized differential quadrature (GDQ) method is employed to discritize the governing differential equations along with simply supported and clamped edge supports. To evaluate the pull-in voltage and vibration frequencies of actuated microplates, the hydrostatic-electrostatic actuation is assumed to be calculated by neglecting the fringing field effects and utilizing the parallel plate approximation. Also, a comparison between the pull-in voltages predicted by the strain gradient theory and the degenerated ones is presented. It is revealed that increasing the dimensionless internal length scale parameter or decreasing the applied hydrostatic pressures leads to higher values of the pull-in voltage. Moreover, it is found that the value of pull-in hydrostatic pressure decreases corresponding to higher dimensionless internal length scale parameters and applied voltages.     

Remove Degeneracy in Relativistic Symmetries for Manning-Rosen Plus Quasi-Hellman Potentials by Tensor Interaction

The relativistic Dirac equation under spin and pseudo-spin symmetries is investigated for Manning-Rosen plus quasi-Hellman potentials with tensor interaction. For the first time we consider the Hulthen plus Yukawa for tensor interaction. The Formula method is used to obtain the energy eigen-values and wave functions. We also discuss about the energy eigen-values and the Dirac spinors for the Manning-Rosen plus quasi-Hellman potentials for the spin and pseudo-spin symmetry with Formula method. To show the accuracy of the present model, some numerical results are shown in both pseudo-spin and spin symmetry limits.     

The control of the nonlinear optical response of semiconductor quantum dots

In the present work, we investigate the nonlinear optical properties emerged from excitonic features in an experimentally realized spherical parabolic semiconductor quantum dot (QD). The lowest exciton states together with relevant wave functions are calculated through the expansion method with direct matrix diagonalization method within the effective mass approximation. The effect of the size of QD and confinement potential in exciton state is studied in details. Results show that with increasing the size of the QD the energy of exciton decreases because of decreasing of the effect of coulomb potential. Using the compact density matrix formalism second order nonlinear optical rectification (χ(2)${\chi }^{(2)}$) are obtained. By means of the applied electric and magnetic field we manipulate the exciton states and control the nonlinear optical response in a typical GaAs, InAs, CdSe QDs. Our model system presents a way to control the performance of excitonic optoelectronic devices based on semiconductor nanostructures.