New organic materials based on D–π–A structure for application in dye-sensitized solar cells

Research on Chemical Intermediates - We used density functional theory at B3LYP level with 6-31G(d,p) basis set for all atoms to study the electrochemical, photovoltaic, and absorption properties...     

Modeling of Neurodegenerative Diseases Using Discrete Chaotic Systems

Parkinson's and Huntington's diseases are two of the most common neurodegenerative disorders.Tremor, muscle stiffness, and slowness of movement are symptoms of Parkinson's disease. The symptoms of Huntington's disease are severe reduction in muscle control, emotional disturbance, and pathological disorders in brain cells.These diseases are caused by destruction of the cells that secrete a substance called dopamine. In this paper,a new discrete chaotic system is introduced,which can mimic the brain's behavior for neurodegenerative diseases such as Parkinson,Huntington, and Hypokinesia. This system is described based on the similarity between the brain's behavior in normal and abnormal conditions and the chaotic systems. Bifurcation analysis is carried out with respect to different parameters, providing full spectrum of the behavior for different parameter values.Our results can be used to mathematically study the mechanisms behind these diseases.     

Three‐dimensional flow of upper‐convected Maxwell (UCM) fluid

An analysis has been carried out for three‐dimensional fluid over a stretching surface. Similarity transformations are invoked for the conversion of nonlinear partial differential equations to the ordinary differential equations. Computations for the series solution are made by using homotopy analysis method. Graphical results are obtained. Attention has been particularly given to the influence of Deborah number. Copyright © 2010 John Wiley & Sons, Ltd.     

Effects of heat and mass transfer on peristaltic flow of Williamson fluid in a non‐uniform channel with slip conditions

The combined influence of heat and mass transfer has been explored in a study of peristaltic transport of magnetohydrodynamic Williamson fluid in a non‐uniform channel with flexible walls. The slip conditions are paid due attention and long wavelength and small Reynolds number assumptions are adopted in the problem formulation. The obtained results are valid for small Weissenberg number. A detailed study of involved key parameters in the obtained solutions is made by the sketched graphs. Copyright © 2010 John Wiley & Sons, Ltd.     

Entropy production minimization and non-Darcy resistance within wavy motion of Sutterby liquid subject to variable physical characteristics

Journal of Thermal Analysis and Calorimetry - Non-Darcy resistance in peristaltic transport of Sutterby liquid in curved configuration is modeled. Variable characteristics of material (i.e.,...     

Characterization of the sorption behavior and mechanism of U(VI) on sericite by batch experiments and spectroscopic techniques

This study explored the sorption behavior and mechanism of U(VI) on sericite. The surface properties of sericite were investigated, and the effects of several environmental factors on U(VI) sorption to sericite were evaluated. The experimental data were simulated by different isotherm models and kinetic models. Humic acids affects U(VI) sorption obviously while silicate promotes the process in the whole pH range. The sorption–desorption hysteresis suggests an irreversible sorption process. Spectroscopic analyses indicate that the ?OH groups have an important effect in the U(VI) sorption.     

Convective heat and mass transfer in three-dimensional mixed convection flow of viscoelastic fluid in presence of chemical reaction and heat source/sink

Heat and mass transfer effects in the three-dimensional mixed convection flow of a viscoelastic fluid with internal heat source/sink and chemical reaction have been investigated in the present work. The flow generation is because of an exponentially stretching surface. Magnetic field normal to the direction of flow is considered. Convective conditions at the surface are also encountered. Appropriate similarity transformations are utilized to reduce the boundary layer partial differential equations into the ordinary differential equations. The homotopy analysis method is used to develop the solution expressions. Impacts of different controlling parameters such as ratio parameter, Hartman number, internal heat source/sink, chemical reaction, mixed convection, concentration buoyancy parameter and Biot numbers on the velocity, temperature and concentration profiles are analyzed. The local Nusselt and Sherwood numbers are sketched and examined.     

Comparison between the HAM and HPM solutions of thin film flows of non-Newtonian fluids on a moving belt

In this paper, we prove in general that the homotopy perturbation method (HPM) proposed in 1998 is only a special case of the homotopy analysis method (HAM) profound in 1992 when ħ = −1. Besides, by using the thin film flows of Sisko and Oldroyd 6-constant fluids on a moving belt as examples, we show that the solutions given by HPM (Siddiqui, A.M., Ahmed, M., Ghori, Q.K.: Chaos Solitons and Fractals (2006) in press) are divergent, and thus useless. However, by choosing a proper value of the auxiliary parameter ħ, we give convergent series solution by means of the HAM. These two examples also show that, different from the HPM and other traditional analytic techniques, the HAM indeed provides us with a simple way to ensure the convergence of the solution.