HIGH-PERFORMANCE GAS DIFFUSION POROUS STARVED OF ELECTROLYTE SOLUTION

The performance of gas diffusion porous electrode starved of electrolyte solution can be significantly increased by decreasing the thickness of uneven liquid film covering the catalyst agglomerates.

THE STABILITY AND CONVERGENCE OF THE FINITE ANALYTIC METHOD FOR THE NUMERICAL SOLUTION OF CONVECTIVE DIFFUSION EQUATION

In this paper we make a close study of the finite analytic method by means of the maximum principles in differential equations and give the proof of the stability and convergence of the finite analytic method.

STABILITY OF STATIONARY STATE SOLUTION FOR A REACTION DENSITY-DEPENDENT DIFFUSION EQUATION

In this paper we are interested in the large time behavior of the nonlinear diffusion equationWe consider functions which allow the equation to possess traveling wave solutions. We first present an existence and uniqueness as well as some comparison principle result of generalized solutions to the Cauchy problem. Then we give for some threshold results, from which we can see that u=a is stable, while u= 0 or u=1 is unstable under some assumptions, etc.

Equilibrium Swelling and Solute Diffusion Characteristics of Poly (Methacrylic Acid co-Poloxamer) Hydrogels

Poly(methacrylic acid co-poloxamer) hydrogel networks were synthesized by free radical solution polymerization and their equilibrium swelling and solute permeation properties were characterized. These gels exhibited pH dependant swelling and solute diffusivity due to the formation or disruption of hydrogen bonded complexation between methacrylic acid (MAA) and etheric (EO). In neutral and basic conditions (above the swelling transition pH), the copolymer swelling was greatly higher than acid condition. In complexed hydrogels, the diffusion coefficients of vitamin B12 (VB12) were in the range of 10-10 to 10-7 cm2s-1; While in uncomplexed hydrogels, the values were about 210-6 cm2s-1. The comonomer composition and synthesis conditions have great effect on the structure, and thereby, swelling and solute diffusion characteristics of the resultant hydrogels. For the copolymers with composition of less than or more than 1:1 MAA/EO molar ratio, the plot of lnD vs 1/H-1 followed two different linear equations of 慺ree volume theory? respectively.

Analytical quality-by-design approach for sample treatment of BSA-containing solutions

The sample preparation of samples conlaining bovine serum albumin（BSA）,e.g..as used in transdermal Franz diffusion cell（FDC） solutions,was evaluated using an analytical qualily-by-design（QbD）approach.Traditional precipitation of BSA by adding an equal volume of organic solvent,often successfully used with conventional HPLC-PDA,was found insufficiently robust when novel fused-core HPLC and/or UPLC-MS methods were used.In this study,three factors（acetonitrile（%）.formic acid（%） and boiling time（min）） were included in the experimental design to determine an optimal and more suitable sample treatment of BSAcontaining FDC solutions.Using a QbD and Derringer desirability（D） approach,combining BSA loss,dilution factor and variability,we constructed an optimal working space with the edge of failure defined as D〈0.9.The design space is modelled and is confirmed to have an ACN range of 83 ± 3% and FA content of 1 ±0.25%.

Physical Diffusion and Electron-transfer Dynamics of Electroactive Solutes in Polymer Electrolytes Ⅲ. Effect of the Polymer Solvents

The diffusion coefficients(Dapp) and the heterogeneous electron transfer rate constants(ks)for ferrocene in several polymer solvents were determined by using steady-stae voltammetry. Thetemperature dependence of the two parameters indicates Arrhenius behavior. The polymer solventeffects on diffusion and electron transfer dynamics of ferrocene were discussed

THE SOLUTIONS OF STEADY－STATE CONVECTION EQUATIONS IN THE SPACES THAT POSSESS RESTORI NGNUCLEUS

In this paper ,in the space that possesses restoring nucleus, we obtain analyticsolutions in the series form for the steady-state convection diffusion equation The solutions have the following characteristics: (1) they ave given in the accurate form:(2)they can be calculated in the explicit way, without solving the eguations;(3) the error of the approximate solution will be monotonically decreased under the meaning of the norm of the spaces when a cardinal term is added in the procedure of numerical solution .Finally, we calculated the example in [2] the result shows that our solution is more accurate than that in [2].

Physical Diffusion and Electron-transfer Dynamics of Electroactive Solutes in Polymer Electrolytes Ⅰ. Effect of the Nature of Electroactive Solutes

The diffusion coefficients(Dapp) and the heterogeneous electron-transfer rate constants(ks)for ferrocene and its seven derivatives in MPEG/LiClO4 electrolyte were determined by using steadystate voltammetry. The two parameters increase with increasing temperature, indicating Arrhenius behavior. The effects of the nature of electroactive solute molecules on Dapp, ks, and the half-wave potentials(E1/2) are discussed.

Physical Diffusion and Electron-transfer Dynamics of Electroactive Solutes in Polymer Electrolytes Ⅱ. Effect of the Ionic Size of Supporting Electrolytes

The ditheion coefficients(Dapp) and the heterogeneous electron-transfer rate constan(ks)for ferrocene in MPEG/salt electrolytes were determined by using Steady-stae voltammetry. The temperature dependence of the two parameters obeys the Arrhenius equstion. The effect of the ionic size of sir supporting electrolytes on diffusion and electron transfer dynamics of fermcene was discussed

Simulation of microstructural evolution in directional solidification of Ti-45at.%Al alloy using cellular automaton method

The microstructural evolution of Ti-45 at.%Al alloy during directional solidification was simulated by applying a solute diffusion controlled solidification model.The obtained results have shown that under high thermal gradients the stable primary spacing can be adjusted via branching or competitive growth.For dendritic structures formed under a high thermal gradient,the secondary dendrite arms are developed not very well in many cases due to the branching mechanism under a constrained dendritic growth condition.Furthermore,it has been observed that,with increasing pulling velocity,there exists a cell/dendrite transition region consisting of cells and dendrites,which varies with the thermal gradient in a contradicting way,i.e.increase of the thermal gradient leading to the decrease of the range of the transition region.The simulations agree reasonably well with experiment results.

Numerical Simulation for Bioconvection of Unsteady Stagnation Point Flow of Oldroyd-B Nanofluid with Activation Energy and Temperature-Based Thermal Conductivity Past a Stretching Disk

A mathematical modeling is explored to scrutinize the unsteady stagnation point flow of Oldroyd-B nanofluid under the thermal conductivity and solutal diffusivity with bioconvection mechanism.Impacts of Joule heating and Arrhenius activation energy including convective boundary conditions are studied,and the specified surface temperature and constant temperature of wall(CTW)are discussed.The consequences of thermal conductivity and diffusivity are also taken into account.The flow is generated through stretchable disk geometry,and the behavior of non-linear thermal radiation is incorporated in energy equation.The partial differential equations governing the fluid flow in the structure is reduced into dimensionless nonlinear ODEs by applying suitable similarity variables.The obtained system of non-dimensional nonlinear ODEs is treated numerically with the help of bvp4c solver in Matlab under shooting algorithm.The impact of various prominent parameters on velocity profile,thermal profile,volumetric nanoparticle concentration and microorganism distribution is depicted in graphical form.The numerical outcomes for skin friction coefficient,heat transfer rate,Sherwood number as well as microorganism density number versus various parameters are listed in the tables.The results show that fluid velocity is reduced by increasing buoyancy ratio parameter,while the fluid flow increases with mixed convective parameter.The temperature profile is enhanced with the amount of nonlinear thermal radiation and temperature dependent thermal conductivity.Furthermore,concentration profiles of nanoparticles have opposite behavior for Brownian motion coefficient and thermophoresis diffusion parameter,and it is noticed that by varying Peclet number the microorganisms profile is declined.The proposed study is useful to control and optimize heat transfer in industrial applications.

SINGULAR PERTURBATION OF INITIAL BOUNDARY VALUE FROBLEMS OF REACTION DIFFUSlON EQUATION WITH DELAY

In this paper we consider the initial-boundary value problems for a class ofapplications, such as biomathematics and biochemistry.Applying the method ofcomposile expansion we construct the formally asymptotic solution of the problemdescribed. With the help of theory of upper and lower solutions we prove the uniformlyvalidity of the formal solution and the existence of solution of the original problem.

Magnetohydrodynamic slip flow and diffusion of a reactive solute past a permeable flat plate with suction/injection

The magnetohydrodynamic(MHD)boundary layer slipflow and solute transfer over a porous plate in the presence of a chemical reaction are investigated.The governing equations were transformed into self-similar ordinary differential equations by adopting the similarity transformation technique.Then the numerical solutions are obtained by a shooting technique using the fourth order Runge-Kutta method.The study reveals that due to the increase in the boundary slip,the concentration decreases and the velocity increases.On the other hand,with an increase in the magneticfield and mass suction,both boundary layer thicknesses decreased.As the Schmidt number and the reaction rate parameter increases,the concentration decreases and the mass transfer increases.

Modeling of Cell/Dendrite Transition During Directional Solidification of Ti-Al Alloy Using Cellular Automaton Method

Solute diffusion controlled solidification model was used to simulate the initial stage cellular to dendrite transition of Ti44Al alloys during directional solidification at different velocities. The simulation results show that during this process, a mixed structure composed of cells and dendrites was observed, where secondary dendrites are absent at facing surface with parallel closely spaced dendrites, which agrees with the previous experimental observation. The dendrite spacings are larger than cellular spacings at a given rate, and the columnar grain spacing sharply increases to a maximum as solidification advance to coexistence zone. In addition, simulation also revealed that decreasing the numbers of the seed causes the trend of unstable dendrite transition to increase. Finally, the main influence factors affecting cell/dendrite transition were analyzed, which could be the change of growth rates resulting in slight fluctuations of liquid composition occurred at growth front. The simulation results are in reasonable agreement with the results of previous theoretical models and experimental observation at low cooling rates.

Study on a General Hopf Hierarchy

By using a general symmetry theory related to invariant functions,strong symmetry operators and hereditary operators,we find a general integrable hopf heirarchy with infinitely many general symmetries and Lax pairs.For the first order Hopf equation,there exist infinitely many symmetries which can be expressed by means of an arbitrary function in arbitrary dimensions.The general solution of the first order Hopf equation is obtained via hodograph transformation.For the second order Hopf equation,the Hopf-diffusion equation,there are five sets of infinitely many symmetries.Especially,there exist a set of primary branch symmetry with which contains an arbitrary solution of the usual linear diffusion equation.Some special implicit exact group invariant solutions of the Hopf-diffusion equation are also given.