Mass conductivity

The intracrystalline diffusivities of the hydrocarbons were measured under the conditions of the temperature range of 373-773 K and the pressure range of 0-1.33 kPa by the constant volume method [9]. The apparatus and the procedure are the same as employed by Hashimoto et al. [4,5]. Change in the total pressure caused by adsorption was recorded by use of a piezometric sensor with a transducer, the response of which is first enough to measure accurately the pressure change. To eliminate the influence of several factors (such as mass conductivity between the sorbate and the pressure sensor) on the pressure change, the blank tests were conducted without zeolites. Comparing these data obtained with those with zeolites, an uptake curve of the amount adsorbed was obtained. 

In order to increase the conductivity from polymers, a variety of cmiductive fillers like carbon black and graphite is available for use in plastics. Because of the structure of carbon black, which contains many pores with small mass, conductive paths in the polymer can be obtained with low critical concentration. Graphite as a filler has a laminated structure and similar electrical characteristics as carbon black. 

Conductivity (electrical) n. The reciprocal of volume resistivity the conductance of a unit cube of material. The SI unit is siemens per meter (S/m). It is measured by the quantity of electricity transferred across unit area, per unit potential gradient per unit time. Reciprocal of resistivity. Volume conductivity or specific conductance, k = lip where p is the volume resistivity. Mass conductivity = kid where d is density. Equivalent conductivity A = kic where c is the number of equivalents per unit volume of solution. Molecular conductivity p = kim where m is the number of moles per unit... 

In the direct measurements, the physicochemical properties of the powder mixture are monitored during the wet-granulation process. These properties could be mass conductivity and granule size. 

All chemical sensors presently in use or in development are based on a two-step detection mechanism [1]. In the first step, chemical selectivity is achieved by a chemical reaction or chemi- or physisorption on a chemically selective surface as listed in table 1. In the second step, a physical change, which is the result of the first selective chemical step, is transformed by a suitable transducer into an electrical signal. This physical change can be a variation of the chemical potential, caused by the reaction or sorption process, a change in optical properties, a change in mass, conductivity, surface resistance or conductance. The physical effects listed in table 2 in column 1 can now be combined with the various transducers listed in column 2 in a suitable way. They will yield the total spectrum of chemical sensor types presently under investigation. 

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