The surface charge on manganese dioxides

Soil Research ◽  
1981 ◽  
Vol 19 (1) ◽  
pp. 41 ◽  
Author(s):  
RM McKenzie
Keyword(s):  
Theoretical Model ◽  
Surface Charge ◽  
Charge Densities

Surface charge was measured on four synthetic manganese dioxides. Charge densities on two cryptomelanes followed closely the values predicted by a theoretical model. Charge densities on two birnessites were much higher, and did not fit the model.

scholarly journals Variation of Streaming Potentials with Time under Steady Fluid Pressure in Bone

2019 ◽  
Vol 9 (18) ◽  
pp. 3726
Author(s):  
Liu ◽  
Hou ◽  
Qin ◽  
Fu ◽  
Pan
Keyword(s):  
Theoretical Model ◽  
Fluid Pressure ◽  
Fluid Flows ◽  
Experimental Setup ◽  
Viscous Resistance ◽  
Streaming Potentials ◽  
Charge Densities ◽  
Holding Period ◽  
Plate Specimen ◽  
Haversian Canals

This paper investigates the streaming potentials’ behaviors when fluid flows through the micropores in bone. An experimental setup was developed for measuring the streaming potentials between two surfaces of a bone plate specimen. It was found that the streaming potentials measured increased almost linearly with time under a constant fluid pressure gradient, which does not agree with the prediction from the classical theory of streaming potentials. To explain the reasons associated with the results obtained, a theoretical model was proposed in which the electric charge densities on the inner surfaces of the capillary are unevenly distributed. A formula was developed for solving the model, and the solutions demonstrate that nonuniform accumulations of electric charges carried by the fluid on the inner surfaces of the microcanals in bone can induce streaming potentials which linearly increase with time during the driving air pressure holding period. This phenomenon represents the specific characteristics of bone. The solution implies that the streaming potentials in Haversian canals, lacunas and canaliculi are not affected by electro-viscous resistance in the bone fluid.

Surface Charge Densities of Two Actinide(IV) Oxides: UO2 and ThO2

2002 ◽  
Vol 256 (2) ◽  
pp. 256-261 ◽  
Author(s):  
Mattias Olsson ◽  
Anna-Maria Jakobsson ◽  
Yngve Albinsson
Keyword(s):  
Surface Charge ◽  
Charge Densities

Fast Evaluation of Differential Capacity and Surface Charge in Electrical Double Layers with A.C. Oscillopolarography

2000 ◽  
Vol 65 (3) ◽  
pp. 371-379 ◽  
Author(s):  
Shuping Bi ◽  
Hong Gao ◽  
Wei Tang ◽  
Zhiguo Yang ◽  
Sidan Du ◽  
...  
Keyword(s):  
Surface Charge ◽  
Analytical Procedure ◽  
Low Cost ◽  
Mercury Electrode ◽  
Double Layers ◽  
Differential Capacity ◽  
Fast Evaluation ◽  
Charge Densities ◽  
Electrical Double Layers ◽  
Simple Manipulation

The application of a.c. oscillopolarography for a fast evaluation of differential capacity and surface charge in electrical double layers on the mercury electrode is described. The Cd = f(E), Q = f(E) and γ = f(E) functions are displayed. The obtained values of differential capacity and surface charge densities are in agreement with those from the a.c. bridge method. The new method has the distinct advantages of a rapid analytical procedure, visual detection, very simple manipulation and low-cost instrumentation. It is very useful in practical analysis where accurate values of differential capacity and surface charge are not required.

Interface Analysis of a Combined Electroosmotic/Pressure Driven Flow of Three Viscoelastic Immiscible Fluids in a Microchannel

2017 ◽  
Author(s):  
Juan P. Escandón ◽  
Juan R. Gómez ◽  
Clara G. Hernández
Keyword(s):  
Surface Charge ◽  
Slip Surface ◽  
Flow Behavior ◽  
External Pressure ◽  
Immiscible Fluids ◽  
Charge Densities ◽  
Poisson Boltzmann Equation ◽  
Pressure Driven Flow ◽  
Viscous Stresses ◽  
Pressure Driven

This paper presents the analytical solution of a combined electroosmotic/pressure driven flow of three viscoelastic immiscible fluids in a parallel flat plate microchannel. The mathematical model is based in the Poisson-Boltzmann equation and Cauchy momentum conservation equation. In the steady state analysis, we consider that the three fluids are electric conductors and obey to the simplified Phan-Thien-Tanner rheological model; therefore, different conditions at the interface between the fluids as electric slip, surface charge density and electro-viscous stresses balance are discussed in detail. Results show the transport phenomena coupled in the description of the velocity profiles, by the analyzing of the dimensionless parameters obtained, such as: the electric slips, the electric permittivities ratios, the surface charge densities, the zeta potentials at the walls, the interfaces positions, the viscosity ratios, the viscoelastic and electrokinetic parameters, and the term involving the external pressure gradient. Here, the presence of a net electric charges balance at the interface, breaks the continuity of shear viscous stresses, modifying the flow field; hence, for the established electric conditions at the interface through the values of the electric slips and the surface charge densities, play a role like a switch on the flow behavior. This investigation extends the knowledge about the techniques on the control of immiscible non-Newtonian fluids in microescale.

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