Coefficient voltage efficiency

A coefficient voltage efficiency (f/ ) was introduced to characterize the charge/ discharge voltage ratio ... 

The alternating component of the applied voltage causes a continuous variation in the efficiency of the x-ray excitation (Step II) during each cycle of operation. A polychromatic x-ray beam has a different total absorption coefficient and a different ratio of photoelectric to scattering absorption coefficient for each wavelength (Step V). It is very difficult to take account of these factors exactly. Fortunately, reasonable estimates will suffice in the making of the calculations for Table 4-4 and Figure 4-15. The efficiency has been taken as that for the root-mean-... 

Battery characteristics depend strongly on the operating temperature. As a rule, both the discharge voltage and the reactant utilization coefficient are lower at lower temperatures. On the other hand, increased temperatures are conducive to side reactions (such as corrosion processes) and thus reduce battery efficiency. Therefore, each battery type is designed for a specific temperature range within which its characteristics will be within the prescribed limits. 

As can be derived from Equation (38) a higher efficiency will be obtained by applying high voltages and for compounds with a high electrophoretic mobility and low diffusion coefficients. It is thereby important not to use very long capillaries. 

The corresponding injection currents for sensitized hole generation are almost independent of the applied voltage. The remaining increase in the quantum efficiency (holes per incident photon) with rising external field strength (Fig. 27) corresponds to a relative linear increase of the current with a coefficient of 10-6... 

Photoelectrochemical cells with polythiophene film as an active electrode and a lead plate as a counter electrode in Pb (C104) acetonitrile electrolyte has an open circuit voltage of 0.8 V, short circuit current of 2 x 10 4 A cm-2, efficiency coefficient of 0.03%, fill factor of 15% [194]. The absorption and photosensitivity spectra of such a cell are shown in Fig. 24. The small bathochromic shift in the longwave region for photosensitivity may be related to the photogeneration of the charge carriers via surface states. The photosensitivity maximum is close to the maximum solar intensity. The parameters exceed the ones obtained with polyacetylene. 

Equation (8.8) shows that the efficiency of separation increases with the applied voltage. Macromolecules, whose diffusion coefficients are lower than those of small molecules, tend to give better separations (Fig. 8.11). 

A sensitive and rapid chromatographic procedure using a selective analytical detection method (electrospray ionization-mass spectrometry in SIM mode) in combination with a simple and efficient sample preparation step was presented for the determination of zaleplon in human plasma. The separation of the analyte, IS, and possible endogenous compounds are accomplished on a Phenomenex Lima 5-/rm C8(2) column (250 mm x 4.6 mm i.d.) with methanol-water (75 25, v/v) as the mobile phase. To optimize the mass detection of zaleplon, several parameters such as ionization mode, fragmentor voltage, m/z ratios of ions monitored, type of organic modifier, and eluent additive in the mobile phase are discussed. Each analysis takes less than 6 min. The calibration curve of zaleplon in the range of 0.1-60.0 ng/ml in plasma is linear with a correlation coefficient of >0.9992, and the detection limit (S/N = 3) is 0.1 ng/ml. The within- and between-day variations (RSD) in the zaleplon plasma analysis are less than 2.4% (n = 15) and 4.7% (n = 15), respectively. The application of this method is demonstrated for the analysis of zeleplon plasma samples [14]. 

The efficiency is therefore directly proportional to the the applied voltage (V) and inversely proportional to the diffusion coefficient of the analyte (D). The sum of contributions from electoosmotic flow (/ ,) and the electrophoretic mobility (fiel) result in the overall, or apparent, electrophoretic mobility of the analyte ... 

Efficiency, N, is a number that describes peak broadening as a function of migration time. High voltages, fast migration times, and species with low diffusion coefficients result in the most efficient separations. 

In CE, these two separation parameters, theoretical plate number and resolution, are functions of both the electrophoretic mobility of the analytes and EOF mobility. N is increased with increases in electrophoretic mobility and applied potential, but it decreases with an increase in the diffusion coefficient. R in turn increases with electrophoretic mobility and applied voltage but decreases with diffusion coefficient. In general, both efficiency and resolution are higher at higher voltages and in the presence of substances having small diffusion coefficients. 

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