Effect of lead foam grid on performance of lead-acid battery

In order to increase the specific energy and specific power of a lead-acid battery, lead foam grid was prepared by electrodepositing Pb-Sn alloy on a copper foam substrate and used as negative current collector for a lead acid battery whose capacity was limited by the negative plate. Comparing the effect of the cast grid, under the same conditions, the mass of lead foam grid decreases by 35%, and the area of lead foam contacted with active material increases by about 20 times. Under 2 h rate discharge condition, with a high current （3 0 I2） e and low-temperature （-10 ℃, I2） discharge system, the lead foam grid markedly boosts the discharge performance of lead acid battery. It increases not only the negative electrode mass specific capacity by 27%,37% and 29%,but also the utilization efficiency of the negative active material by 5%. Compared with the negative electrode of cast grid, XRD and SEM results show that after 20 cycles at the state of charge, the sponge lead in the negative lead foam electrode has smaller crystals and less PbSO4 on its surface. Meanwhile, at the state of full discharge, the PbSO4 crystals are smaller and occur less on the surface of lead foam electrode. This indicates its active material reacts more uniformly.

Regression analysis and features of negative activation energy for MHD nanofluid flow model:A comparative study

This article elucidates the impact of activation energy on magnetohydrodynamic(MHD)stagnation point nanofluid flow over a slippery surface in a porous regime with thermophoretic and Brownian diffusions.Negative activation energy is scarce in practice,but the impact of negative activation energy could not be neglected as it is noticed in chemical processes.The rate of some Arrhenius-compliant reactions is retarded by increasing the temperature and is therefore associated with negative activation energies,such as exothermic binding of urea or water.In some processes,the temperature dependence of the pressure-induced unfolding and the urea-induced unfolding of proteins at ambient pressure give negative activation energies.The present mathematical model is solved with successive linearization method(a spectral technique).A comparison of results is made for negative and positive values of activation energy.Apart from it,the quadratic multiple regression model is discussed briefly and explained with bar diagrams.It is observed that with rise in unsteadiness parameter from 0 to 1(taking positive activation energy),skin friction and Sherwood number are increased by 9.36%and 19%respectively,and Nusselt number is decreased by 26%.However,for negative activation energy,9.36%and 112%enhancement is observed in skin friction and Sherwood number,respectively.

Efficacy observation of Yiguanjian decoction combined adefovir Dipivoxil tablet in treating HBeAg negative chronic viral hepatitis B active compensated liver cirrhosis patients

Objective To explore clinical efficacy of Yiguanjian Decoction(YD)combined Adefovir Dipivoxil Tablet(ADT)in treating HBe Ag negative chronic viral hepatitis B(CVHB)active compensated liver cirrhosis(LC)patients.Methods Totally 68 HBe Ag negative CVHB active compensated LC patients initially treated were assigned to the treatment group and the control group