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著者人数: 19名, Accepted: 2017-10-03, 資料番号: SA1170306000

Streaming potentials and conductivities of close-packed plugs of spherical Stober-silica particles were measured. Stober silica is highly porous; more than 98% of the countercharge may be situated inside the particle. Only the countercharge in the double layer region outside the porous particle contributes to the plug conductivity and the streaming potential. The countercharge obtained from plug conductivities is less than the double layer charge obtained from titrations. The countercharge obtained from streaming potentials is less than obtained from plug conductivities, which indicates the occurrence of conduction behind the shear plane. It is essential to take this conduction into proper account in order to arrive at more realistic ζ -potentials.

The aim of this communication is to show how a very simple stagnation plate positioned transversally to the of an air-ethylene premixed flame ([C]/[O]=1.38) does introduce significant changes in both flame temperature, soot 2D distribution and, moreover, does produces a dramatic increase of the soot particle residence time about a factor 6-8 with respect to the identical flame without the stagnation plate. This has crucial effect of the possibility to modulate the permanence time of the carbon particle in the high-reactive flow according to the design of the burner system.

Based on physical modeling and analytical estimation of the possibility (probability) of the coagulation of oxide nonmetallic inclusions in steel, it is concluded that pulsed feeding of an inert gas through a porous ladle bottom provides better conditions for the coagulation and emersion of inclusions than during traditional blowing through porous plugs. © 2013 Pleiades Publishing, Ltd.

Streaming potential and conductivity measurements were performed on porous plugs in a number of indifferent electrolytes. The plugs were made of monodisperse spherical polystyrene sulfate latex with fixed surface charge density. The observed surface conductivity could be interpreted with the classical Bikerman expression extended with the contribution from conduction behind the shear plane. It was shown that electroosmosis contributes positively, while the depletion of co-ions in the double layer contributes negatively to the surface conductivity. It was further demonstrated that a significant part of the conduction is located behind the slip plane. The ion mobility of the indifferent counterions behind, as well as beyond, the shear plane is close to the bulk mobility. In the correct determination of ζ-potentials in the low electrolyte concentration range, it is necessary to take surface conduction behind the plane of shear into account. When this is done, the maximum in the curve of the ζ-potential versus electrolyte concentration disappears.