Electrical conductivity change

The diversity of EEP reactions on a solid surface can be illustrated by the survey if interaction between excited atoms of mercury and zinc oxide [186]. When atoms of Hg get to an oxidized surface of ZnO at room temperature, an increase in the semiconductor electrical conductivity take place (Fig. 5.3, curve 2). The electrical conductivity change signal is irreversible, and in case of an increase in the temperature, after the Hg flux is disabled, an additional increase in the electrical conductivity (curves 3 and 4) takes place. One can logically suppose that we are dealing here with partial reduction of zinc oxide according to the scheme... 

The sensor detection of EEPs is methodically more complicated than the detection of atoms and radicals. With atoms and radicals being adsorbed on the surface of semiconductor oxide films, their electrical conductivity varies merely due to the adsorption in the charged form. If the case is that EEPs interact with an oxide surface, at least two mechanisms of sensor electrical conductivity changes can take place. One mechanism is associated with the effects of charged adsorption and the other is connected with the excitation energy transfer to the electron... 

Electrical Conductivity. Changes in the electrical conductivity within or on the surface of a photopolymer film can be used to visualize the results of a photochemical reaction. A limited number of electrophotographic/electrostatic processes have been developed employing this readout method (22). 

Biomolecules-functionalized CNTs can result in characteristic electric conductivity changes of CNTs (Hou et al., 2003), which may be developed into specific biosensor for ultrasensitive detection of biomolecules such as DNA molecules, bacteria and vims, etc. We also observed that oligo DNA-filled SWCNTs appeared as characteristic Electric Resistance peaks as shown in Fig. 9.22, which also may be used as biosensor to detect biomolecules or sequence DNA sequences. 

Soc. Japan 47 1139-1142 Kaneko, K. Inouye, K. (1976) Electrical conductivity changes in a-FeOOH and K-FeOOH upon surface dehydration. Bull. Chem. Soc. Japan 49 3689-3690... 

With these understandings, the principal electrical conduction changes observed in [TCNQ-TTF] at each temperature range can now be compared against the Covalon model proposed in the following manner, (refer to Figs. 15 16). 

Burton and Praill were the first to prqjare this ecies both by the interaction of perchloric acid with acetic anhydride and the metathetic reaction of sflver perchlorate with acetyl chloride , in a comprehensive study of acylation reactions. They did not attempt a characterisation of the compound and assumed that in acid solutions it existed in a fully ionised form. A few years later, Jander and Surawski followed the formation of acetyl perchlorate in acetic anhydride by measuring the electrical conductivity changes which took place when acetyl bromide was added to silver perchlorate or vice versa. In both titrations an inflection point was observed for a mixture of equimolar quantities of the two reactants indicating the formation of acetyl perchlorate. Moreover, it was clearly drown that this compound was at least partly ionised since its conductivity was higher than that of acetyl bromide. Avedikian and Commeyras characterised acetyl perchlorate by infrared and Raman spectroscopy both in acetic anhydride and carbon tetrachloride. They concluded that some ionisation was present but could not assess its extent. Molecular acetyl perchlorate was also detected. As far as we are aware, no other study of the structure and extent of dissociation of acetyl perchlorate in solution has been conducted. 

A very interesting method to analyze total carbon dioxide and ammonium in pore water was introduced by Hall and Aller (1992). In this method, a sample carrier stream and a gas receiver stream flow past one another, separated only by a gas-permeable PTFE (Teflon ) membrane. For determining the total COj, the sample carrier stream consists of 10-30 mM HCl. To this stream, the sample in a volume of about 20 [tl is added via a HPLC injection valve. The carbon dioxide traverses the PFTE membrane and enters the gas receiver stream which, in this case, consists of 10 mM NaOH. The CO taken up by the gas receiver stream causes an electrical conductivity change that can be determined exactly in a micro-sized continous flow cell. 

A composite ceramic Zr02-Mg0 with porous structure and n-type semiconductivity is a promising material [30]. When the Zr02-MgO ceramic at high temperature between 400 °C and 700 "C is exposed to an ambient atmosphere containing water vapor, reversible chemisorption becomes dominant and the electrical conduction changes with gas chemisorption. 

Semiconductor gas sensor is based on electrical conduction changes, caused... 

Bott B, Jones TA (1984) A highly sensitive NO sensor based on electrical conductivity changes in phthalocyanine films. Sensor Actuator 5 43-53... 

Fig. 2.6 Electrical conductivity change upon mixing of various rare-earth ions in ZrO at 1,273 K. (Reprinted with permission from Imanaka and Adachi (1997). Copyright 1997 Elsevier)...

As has been demonstrated, the fields of quartz crystal microbalance (QCM)- and surface acoustic wave (SAW)-based gas sensors are also of interest in metal film application (Miura 1991 Jakubik etal. 2003 Jakubik and Urbanczyk 2005). When the palladium or palladium-based alloy layer absorbs hydrogen, both its mass density and electrical conductivity change, and this produces a detectable change in the frequency of the SAW and resonance frequency of (JCM. Devices were able to detect hydrogen gas in a range of 1.5-4.0% concentration in air. 

The electric conductivity changed with increasing pressure in the )2 suspension. The plausible reactions,... 

During MEF treatment, the eleetrie field may cause changes in the permeability of plant cell membranes at temperatures below those at which thermal permeabilization occurs (Personius Sharp, 1938). Diffusion is enhanced, electrical conductivity changes are more linear during heating, and moisture migrates more easily out of the tissue. (Lima et al., 2001 Schreier et al., 1993). Electropermeabilization is a mechanism that can accormt for these... 

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