Lowest carrier transport

The exponent n is dose to 0.5 for pure polypropylene and points to diffusive carrier transport. For the composites, n changes from about 0.5 at the low frequencies to 1 at the high frequencies. This fact proves the existence of diffusive as well as hopping carrier transport. In the lowest frequency range the compiosite samples show the frequency-independent behavior pointing to the ohmic conduction. This property makes them to be better antistatic material than pure propylene. 

All the CO resulting from the pseudo solid-solid reaction is conducted, together with entrained char, from the top fluidized section through a constriction, in which the high-velocity gas flow prevents backflow, to a transport combustor, where the CO is burned to C02 with preheated air, along with as much of the char as is called for by heat balance to maintain the endothermic FeO-C reaction. The heated recycled char is separated from the off gas at the top of this transport combustor in a hot cyclone and is returned as a thermal carrier to the lower part of the lowest j igged section, while the hot flue gas from the transport combustor is used to preheat the incoming air in a recuperator. 

Optimization of System Variables. The dependence of the blank level and the total signal (blank + analyte response) on the liquid flow rate is shown in Figure 10. The conditions are the same as those for Figure 9 except that 10"6 M Hg2(N03)2 at pH 4 is used. Down to the lowest flow rate studied (1500 / L/min), the net response to 5 ppbv S02 is essentially constant. Unfortunately, this flow rate dependence was examined fairly late in the study and the other data reported here were obtained with a liquid flow rate of 2600 pL/min. It is clear, however, that down to at least 1500 nL/min, the response/blank ratio improves it may be advantageous to use a lower flow rate. This behavior also strongly suggests that the transport of mercury from the bulk solution (liberated due to the intrinsic disproprotionation equilibrium) to the carrier air stream is controlled by liquid phase mass transfer. 

The third relaxation process is located in the low-frequency region and the temperature interval 50°C to 100°C. The amplitude of this process essentially decreases when the frequency increases, and the maximum of the dielectric permittivity versus temperature has almost no temperature dependence (Fig 15). Finally, the low-frequency ac-conductivity ct demonstrates an S-shape dependency with increasing temperature (Fig. 16), which is typical of percolation [2,143,154]. Note in this regard that at the lowest-frequency limit of the covered frequency band the ac-conductivity can be associated with dc-conductivity cio usually measured at a fixed frequency by traditional conductometry. The dielectric relaxation process here is due to percolation of the apparent dipole moment excitation within the developed fractal structure of the connected pores [153,154,156]. This excitation is associated with the selfdiffusion of the charge carriers in the porous net. Note that as distinct from dynamic percolation in ionic microemulsions, the percolation in porous glasses appears via the transport of the excitation through the geometrical static fractal structure of the porous medium. 

As designed, the reactor bears some resemblence to a dilute-phase transport reactor in that the solids and volatile pyrolysis products are present only in low concentrations in the steam reactant. During pyrolysis.the composition of gas in the gas-phase reactor using the lowest steam flow and a 0.1 g sample is nominally 68% steam. 28% volatiles, and 4% argon carrier (on a volume percent basis). Somewhat larger samples, leading to an increase in volatile concentrations, do not markedly affect the results reported here. 

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