Conductivity reproducibility

FIGURE 6.7 Schematic of the pressure vessel and needle probe system used to measure thermal conductivity. (Reproduced from Waite, W.F., deMartin, B.J., Kirby, S.H., Pinkston, J., Ruppel, C.D., Geophys. Res. Lett., 29, 2229 (2002). With permission from the American Geophysical Union.)... 

These were attached to a fraction collector, whose timing mechanism was altered to allow continuous sampling of 28 separate diffusion cells with increased sample and timing capacity. Radiolabeled drugs were used and were measured in a liquid scintillation counter directly interfaced to a computer network. We describe the details of this system which enable us to conduct reproducible flow-through diffusion experiments, assay the samples, and analyze the data quickly and efficiently. 

Fig. 9.38 Reflectivity and optical conductivity of PAni doped with AMPSA. A localisation-modified Drude model (LMDM) is used to fit the optical conductivity. Reproduced with permission of the Institute of Physics from Tzamalis et al. (2001).

Figure 8. Simultaneous shrinkage and conductance measurements with Leigh Creek (Australian) coal ash. A, shrinkage and B, conductance. Reproduced with permission from reference 2. Copyright 1985 Hemisphere Publishing Corp.

Figure 12. Cell motility assay using the computer-controlled LCD images, (a) An image to measure the ratio of Tetrahymena trap. Trapped cells were marked with black arrows, (b) The ratios of aligned Tetrahymena according to the light contrast. At least five rephcates were conducted. (Reproduced with permission from Ref [25] Copyright 2008, American Institute of Physics.)...

Fig. 11.8 Magic numbers for Ag nanowires for the thinning process (changes in cross section) and the fractional quantum conductance (Reproduced from Ref. [27] with kind permission of The American Physical Society)...

Table 17.1 Atomic composition and dc conductivity. Reproduced by permission of the American Chemical Society (1994)." ...

Figure 58 Schematic illustration of the shear stress versus particle conductivity. Reproduced with permission from T. Hao, H. Yu, and Y. Xu, J. Colloid Interface Sci., 184(1996)542.

Figure 9.3 Temperature dependence of the in situ photoconductance for two Ceo films, using white light intensity of 2 mW/cm. Films were grown on sapphire substrates held at approx. 200°C. Starting Qo powder for film A was dried for a longer period. Inset shows temperature dependence of the dark conductances. (Reproduced by permission of the American Physical Society from ref...

Figure 9.18. Light intensity dependence of the photoconductivity of Cgo and C70 films, taken in air, shortly after sample preparation (open symbols) and after keeping the sample in air for 2 weeks (solid symbols). Horizontal lines indicate values of dark conductivity. (Reproduced by permission of the American Physical Society Irom ref 39.

The theory of percolation helps to interpret this result. Let us consider a uniform network of points in space and let us introduce, progressively, bonds between nodes. At first isolated clusters of different sizes, of connected points are formed. When approaching the critical value p, called percolation threshold, one of these clusters grows very rapidly through the conglomeration of isolated clusters. For values greater than p, this cluster is infinite. The theory of percolation, applied to the study of conductivity, reproduces the equations of the effective medium, except at the immediate vicinity of the percolation threshold, where apparent conductivity then varies like ... 

Fig. 4.27 SEM images of a PAN, b carbon nanofibres without a gold coating and c pyrolysis temperature versus the conductivity. Reproduced from Ref. [274]...

The sample to be analyzed can be dissolved in an organic solvent, xylene or methylisobutyl ketone. Generally, for reasons of reproducibility and because of matrix effects (the surroundings affect the droplet size and therefore the effectiveness of the nebulization process), it is preferable to mineralize the sample in H2SO4, evaporate it and conduct the test in an aqueous environment. 

Pure and almost stoichiometric NiO shows, therefore, a very low conductivity of about 10 (Hem) at 25°C but, as illustrated in Figure 7, this value can be increased to about 1 (Hem) by the addition of lithium (11). This stabilizes the formation of the Nfi" states at a higher concentration, resulting in higher and more reproducible conductivities. Similarly, the insulating characteristics of NiO can be improved by the addition of a stable trivalent ion such as Cr " in soHd solution. This addition decreases the fraction of Nfi" ions formed. Because electron transfer between Ni " and Cr " is not favorable, the overall conductivity is substantially decreased. 

To obtain catalyst of maximum and reproducible activity, it is recommended that the fusion be conducted in a Pyrex beaker or casserole resting in a cavity of a copper block heated with a burner and provided with a thermometer well. Adequate temperature control is thus possible. Short, J. Soc. Chem. Ind. 55, 14T (1936). 

Analyses are types of calculations but may be comparative studies, predictions, and estimations. Examples are stress analysis, reliability analysis, hazard analysis. Analyses are often performed to detect whether the design has any inherent modes of failure and to predict the probability of occurrence. The analyses assist in design improvement and the prevention of failure, hazard, deterioration, and other adverse conditions. Analyses may need to be conducted as the end-use conditions may not be reproducible in the factory. Assumptions may need to be made about the interfaces, the environment, the actions of users, etc. and analysis of such conditions assists in determining characteristics as well as verifying the inherent characteristics. (See also in Part 2 Chapter 14 under Detecting design weaknesses.)... 

Typical magnetoconductance data for the individual MWCNT are shown in Fig. 4. At low temperature, reproducible aperiodic fluctuations appear in the magnetoconduclance. The positions of the peaks and the valleys with respect to magnetic field are temperature independent. In Fig. 5, we present the temperature dependence of the peak-to-peak amplitude of the conductance fluctuations for three selected peaks (see Fig. 4) as well as the rms amplitude of the fluctuations, rms[AG]. It may be seen that the fiuctuations have constant amplitudes at low temperature, which decrease slowly with increasing temperature following a weak power law at higher temperature. The turnover in the temperature dependence of the conductance fluctuations occurs at a critical temperature Tc = 0.3 K which, in contrast to the values discussed above, is independent of the magnetic field. This behaviour was found to be consistent with a quantum transport effect of universal character, the universal conductance fluctuations (UCF) [25,26]. UCFs were previously observed in mesoscopic weakly disordered... 

The resisitivites p corresponding to the DC conductivities results reproduce the measured strong dependence of p on the composition correctly. The CP results agree with the experiments very well. The only exception is the composition with 20% sodium where the relative deviation is about 100% however, the absolute deviation is small. 

Furthermore, the electrical conductivities of liquid Na-Sn alloys for the five compositions are determined with the Kubo-Greenwood scheme, using the trajectories from our ab initio MD simulations. The calculated values reproduce the measured strong variation of the conductivity with the Na (or Sn) concentration very well. The small (semimetallic) conductivity of the alloys with nearly equimolar composition can be explained by the position of the Fermi energy between the occupied sp-band of tin and the sp-band of sodium. 

Although all these complicating factors cannot be reproduced in small-scale tests, it will be of value to summarise the main knowledge that has been gained from long-period burial trials conducted in the United States and in Great Britain . The subject will be considered under two heads effect of metal composition and effect of the soil. 

C. and D. Monoolein/hexadecane membranes, 100 mV applied potential 1 M RbCl and 23 °C. Note that, during the time period of an average Gramicidin A channel (above), the N-acetyl desformyl Gramicidin A channel turns on and off many times and that the conductance step is smaller. The N-acetyl methyl replacing the formyl proton also crowds and destabilizes the head to head junction and results in less favorable lateral coordination of the cation at the junction. Reproduced with permission from Ref.111... 

Fig. 4. A, Histogram of single channel conductances, y, of Gramicidin A in diphytanoyl L-a-lecithin/n-decane membranes for 1 M KC1, 130 mV potential and 40 °C. Note that single channel conductance is simply the single channel current, i , divided by the applied potential. Reproduced from reference 12) with permission.

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