Parallel conductances

Capacitance (C) is the property that describes the quantity of electricity that can be stored when two conductors are separated by a dielectric material. The unit of capacitance is the farad. The capacitance of two equal-area, conducting parallel plates (see Figure 2-64) separated by a dielectric is given by... 

The liner was compacted with two lifts, each 6-in. thick. A 1-ft3 block of soil was carved from the liner, and cylindrical test specimens were trimmed from upper and lower lifts and measured for hydraulic conductivity. A 3-in. diameter specimen also was cut, and hydraulic conductivity parallel to the lift interface was measured. The actual in situ hydraulic conductivity, a high 1 x 10-4 cm/s, was verified both by the infiltration measurements and the underdrain measurements. 

According to the macropore formation mechanisms, as discussed in Section 9.1, the pore wall thickness of PS films formed on p-type substrates is always less than twice the SCR width. The conductivity of such a macroporous silicon film is therefore sensitive to the width of the surface depletion layer, which itself depends on the type and density of the surface charges present. For n-type substrates the pore spacing may become much more than twice the SCR width. In the latter case and for macro PS films that have been heavily doped after electrochemical formation, the effect of the surface depletion layer becomes negligible and the conductivity is determined by the geometry of the sample only. The conductivity parallel to the pores is then the bulk conductivity of the substrate times 1 -p, where p is the porosity. 

This note describes a simple flow in which the Hall currents can be calculated exactly and the results compared with those that follow from the usual simplifying assumptions of reducing in fixed ratios the conductivities parallel and perpendicular to the field lines... 

An interesting experiment on a DNA-based network embedded in a cast film had already been done by Okahata et al. in 1998 [49]. In this pioneering experiment the DNA molecules were embedded (with side groups) in a polymer matrix that was stretched between electrodes (see Fig. 12). It was found that the conductivity parallel to the stretching direction (along the DNA) was 4.5 orders of magnitude larger than the perpendicular conductivity. 

Influence of catalase activity and electrical conductivity. Parallel to the determination of the oxygen activity. Beck and co-workers 38> investigated the activity for the decomposition of hydrogen peroxide by various chelates. In each case, 1 mg of freshly precipitated pigment was added to 1% hydrogen peroxide solution and the velocity of oxygen evolution was determined volumetri-cally. The results summarized in Table 5 show no correlation between electro-catalytic activity and catalase activity. 

Fracture was also conducted parallel to the fiber direction in the same study with the same materials. Micrographs of the fracture surfaces of these composites are shown in Fig. 21. For low levels of adhesion, many bare fibers are detected. As the level of adhesion increases after the fibers are surface treated, both bare and epoxy covered surfaces are detected. An increase in the fracture toughness is measured with... 

The carbon sheets in graphite are separated by a distance of 335 pm and are held together by only London dispersion forces. Atmospheric gases can be absorbed between the sheets, thus enabling the sheets to easily slide over one another. As a result, graphite has a slippery feel and can be used as a lubricant. Because the sheets are so far apart, it s relatively difficult for an electron to hop from one sheet to the next and the electrical conductivity in the direction perpendicular to the sheets is therefore about 104 times smaller than the conductivity parallel to the sheets. 

Theoretical analysis indicates that occurrence of such convective instabilities depends on anisotropy of electrical conductivity and dielectric properties in the initial aligned nematic material. That is, conductivity parallel to the direction of alignment must differ from conductivity perpendicular to this direction. Calculation of the stability condition requires knowledge not only of these anisotropic electrical properties but also of anisotropic elastic and viscous properties which oppose disruption of the alignment and flow. 

The layers in graphite are held together by van der Waals forces only weaklT/1. The sheets may be separated but not readily torn breakage of crystalline graphite parallel to the sheets is easy, but breakage perpendicular to the sheets is difficult. Electrical conductivity parallel to the... 

The structure of graphite allows electrons to move fast within graphene sheets (specific conductivity parallel to... 

Use of ceramic materials in high temperature structural applications is often limited by creep resistance. However, several recent studies have shown that composite reinforcement can drastically reduce the creep rates compared to the unreinforced ceramic matrix.12,20,27-31 Most of these studies have been conducted in air, which is a strong oxidizing environment. In a few cases, investigators have attempted to isolate the effects of oxidation from creep by conducting parallel experiments in both air and inert atmospheres.27,28 The following is a description of the salient points made in these investigations. 

If we follow the integrated signal S (conductance parallel or absorbance perpendicular to the interface), the position dependence disappears resulting in... 

Anisotropic ionic conductivities were also observed for nanostructured 2D films consisting of polymer 12 [28]. The conductivities parallel to the layer are... 

One-dimensional ion conduction is achieved for columnar liquid crystalline ionic liquids 10a,b [29]. In the macroscopically ordered states of these columnar materials, ionic conductivities parallel to the columnar axis (ay) is higher than those perpendicular to the axis (ox)- For example, compound 10b shows the conductivities of 3.1 X 10 S cm (ay), 7.5 x 10 S cm (cJx), and anisotropy (ay/ Qx) of 41 at 100°C. These materials function as self-organized electrolytes. They dissolve a variety of ionic species such as lithium salts. Compound 10b containing LiBp4 (molar ratio of LiBp4 to 10b 0.25) exhibits the conductivities of... 

Thermal conductivity parallel to orientation direction Thermal conductivity perpendicular to orientation direction Long period... 

The treatment of thermal conductivity parallels quite closely the treatment given for viscosity. Let us suppose that we have two parallel plates (Fig. VIII.3) at fixed temperatures Ti and T2, with a fluid between them. 

Tellurium is a p-type semiconductor. The element shows anisotropy in electrical conductivity that is essentially independent of temperature in the range 78-200 K. It has been reported that single crystals grown in vapor show more strongly metallic conductivity parallel to the Te chains. The conductivity of tellurium is much less affected by illumination than that of selenium. 

It exhibits anisotropic physical properties as a result of its crystallographic structure of well-separated parallel sheets of carbon atoms. Thus graphite single cry.stals exhibit far higher electrical and thermal conductivity parallel to the layers of carbon atoms than perpendicular to them. Macroscopically, however, this anisotropy is seldom observable due to the random orientation of the individual particles. 

Greenland, conversely, is characterised by the fact that it is in the northern hemisphere, which contains the largest part of the landmass of the whole Earth (about 67%) and most of the population of our planet. This location, rather close to the industrialised areas of north America, western Europe and northern Russia, does not prevent pollution from easily reaching the ice cap. These opposite peculiarities in terms of geographical location and atmospheric regimes underline why scientists are so interested in conducting parallel research programmes on both ice caps. 

As already noted, temperature may be of crucial importance or it may have little bearing at all. In general, it is wise to duplicate crystallization trials and conduct parallel investigations at 4°C and at 25°C. Even if no crystals are observed at either temperature, differences in the solubility behavior of the protein with different precipitants and with various effector molecules, may give some indication as to whether temperature is likely to play an important role. If crystals are observed to grow at one temperature and not, under otherwise identical conditions, at the another, then further refinement of this variable may be justified. This is accomplished by conducting the trials under the previously successful conditions over a range of temperatures centered on the one that initially yielded crystals. 

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