2.?Design and Modeling2.1. Theoretical and Dimensional Analysis of the Diffuser ElementA schematic of the typical diffuser element is shown in Figure 2, where fluid flow in the positive direction usually depicts flow through the diffuser while fluid will be considered flowing through the nozzle for the negative direction.Figure 2.Fluid flow in a diffuser element.Generally the effectiveness of the diffuser element for applications in valveless micropump is gauged through the flow rectification efficiency.

The flow rectification efficiency is the measure of the ability of the pump to direct the flow in one preferential direction and can be defined as the ratio of the micropump net flow rate, Qnet to the rate of displaced volume, as given by:��=QnetV?(1)The pressure loss for the diffuser element at both the diffuser and nozzle direction can be represented in terms of the pressure loss coefficient, �� as:��Pd=��d 12 ��(QdA)2(2)��Pn=��n 12 ��(QnA)2(3)where �� is the fluid density, Q the mean volumetric flow rate at the throat of the diffuser element and A the cross-sectional area of the throat while the subscripts d and n denote the diffuser and nozzle direction, respectively.Based on the geometrical relationship and continuity equation of fluid flow, the rate of displaced volume satisfy:V?=Qd+Qn(4)Hence solving Equations (1), (2), (3) and (4) simultaneously, the rectification parameter can be obtained as the ratio of the net flow rate to the rate of displaced volume, as given by:��=QnetV?=Qd?QnQd+Qn=��n?��d��n+��d(5)For the same opening angle �� for the diffuser element, the pressur
In the study of electrochemistry the electrode was used for a long time only as a source, or a sink, of electrons provided by an electronic conductor with low resistivity.

This paradigm has changed, largely due to the interest shown by electrochemists in the field of metal oxide semiconductors.In contrast to metal electrodes, metal oxide semiconductor electrodes are well-suited to address some of the fundamental predictions of interfacial electron transfer theories. An ideal semiconductor has no electronic levels in the band gap region; therefore, for an n-type material, only electrons with energies near the conduction band can contribute to the cathodic interfacial current flow.Unlike in a metal electrode, the driving force at a semiconductor electrode cannot be changed by varying the potential of the electrode. This situation occurs because the differential capacitance of a non-degenerately doped semiconductor electrode is much smaller than the differential capacitance of the electrolyte. Essentially all of the applied potential drops across the electrode and not across the electrolyte.