Pumping- current

Recordings of Na/K Pump Current Effects of Cellular Glutathione Manipulation 67... 

Gadsby, D.C., Kimura, J. and Noma, A. (1985). Voltage dependence of Na/K pump current is isolated heart cells. Nature 315, 63-65. 

Shattock M. J. and Matsuura, H. (1993). Measurement of Na -K pump current in isolated rabbit ventricular myocytes using the whole-cell voltage-clamp technique. Inhibition of the pump by oxidant stress. Circ. Res. 72, 91-101. 

Fig. 11.30 Relation between pumping current and emf of the lean bum sensor for various A ( = (air/fuel ratio)/(theoretical air/fuel ratio)) (Soejima and Mase, 1985).

Double-cell 02-sensor with a cavity (a) schematic of the sensor (b) pumping current versus O2 concentration in N2 for two different values of the sensor voltage Vs. The temperature of the device was 760°C. 

In addition to the steady-state mode, the double-cell device of Fig.7 can be operated in the so-called transient and oscillatory modes of operation(18.). In the transient mode, one measures the slope dVg/dt when the pumping current is changed in a stepwise fashion from zero to a constant value. A simple analysis(18) gives the following differential equations for Vg and Pv,... 

The first term in the right-hand side of Eq.(16) is due to the pumping current whereas the second term is due to the diffusion of C>2 through the aperture G. If I is sufficiently large, this diffusion term can be neglected and one then has,... 

One device of this type was discussed by Hickam and Witkowski(23). In the diffusion limited devices that have been discussed, the flow rate of the gas is not normally an important factor. In the Hickam device, however, the gas flow is of paramount importance and new possibilities or complications arise. The structure consists of pump (upstream) and sensor (downstream) cells cylindrically surrounding a flowing stream of gas containing oxygen. The sensor cell EMF is fedback to the pump so that oxygen is either added to or subtracted from the stream in the amount required to keep the sensor EMF at a constant value. For a calibrated device, the amount of pump current required measures the oxygen content of the gas at the inlet of the structure provided the flow rate is held constant. Alternately, if a gas of constant composition were employed, the structure could be used to measure flow rate. 

Fig. 11 Pumping current of the sensor of Fig. 10 as a function of X in a propane burner. X is defined as X —...

Andersen, J.P. Vilsen, B. (1990). Primary ion pumps. Current Op. Cell Biol. 2,722-730. 

The vast majority of pumps currently used in analytical HPLC are of the constant flow variety. With this type of pump, changes in the chromatographic system, for instance those leading to variations in the back pressure experienced by the pump, are compensated for, and the flow rate remains constant this is an important factor in most analytical applications. Two major types of constant flow pump exist the reciprocating piston design and the syringe type. 

The order of magnitude of pumping currents is in the range of -100 to -1,000 x 10 °A. When the hydrocarbon is pumped through Alters or discharged in jet-form, these values may be even larger. 

The ultra-high vacuum chamber is commonly made from stainless steel, and joints of chamber parts are made from crushed copper gaskets. Ultra-high vacuum pressure can be achieved using diffusion pumps, sputter ion pumps or turbomolecular pumps. Currently, sputter ion pumps and turbomolecular pumps are more commonly used than diffusion pumps that may contaminate the chamber by leaking oil gas molecules. 

At temperatures higher than the decay width, T -C ksT -C A, the pumped current exhibits Coulomb oscillations as a function of an applied gate voltage [Blaauboer 2001], The peak heights of these oscillations can be obtained by thermally averaging Eq. (8) as... 

Also here, AR enhances the pumped current in case of symmetric tunnel barriers, while a reduction occurs for asymmetric barriers. Maximum enhancement of 7ns, peak/ N, peak 2.55 is reached for T jT2 1.292. This factor is less than 4, because the average over energy e from which the peak heights (13) are obtained also involves contributions of 7ns [Eq. (8)] further away from resonance, for which 7ns/7n is much less than 4 [consider, e.g., Eq. (11) for e — res = hv /Tf + /2], This results in lower maximal enhancement of... 

Figure 2 Distribution of the pumped current peak heights (17) and (18) for two normal leads (solid line), and one normal and one superconducting lead (dashed line).

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