Search

The impedance spectra of(NH4)3H(SeO4)2 in low and high-conductive phases under various thermodynamic conditions were analyzed. The measurements were performed by the ac admittance technique along the trigonal c axis of the crystal, i.e., along the direction perpendicular to the plane in which, in the superionic phases, a dynamically disordered H-bond network was formed. Activation energies and activation volumes were calculated for different phases of the (NH4)3H(SeO4)2 crystal from the baric dependencies of dc conductivity and they were correlated with pressure coefficients of the phase transitions. The experimental results were analyzed within the classical hopping model, in terms of the strong proton-phonon coupling and polaronic effect. [ABSTRACT FROM AUTHOR]

The effect of hydrostatic pressure on proton conductivity of (NH4)3H(SeO4)2superionic crystal was studied in a wide temperature range and different isobaric conditions by means of impedance spectroscopy method. The measurements were performed along the trigonal c axis of the crystal, i.e., along the direction perpendicular to the plane in which, in the superionic phases, a dynamically disordered H-bond network is formed. The obtained pressure-temperature phase diagram is linear with increasing pressure. The triple point, which is the point of coexistence of the three phases: ferroelastic phase IV, ferroelastic phase III, and superionic phase II was found at p=116.3 MPa and T=287.3 K. High pressure leads to increase in the temperature range of stability of both superionic phases and to a drastic decrease in the temperature width of the ferroelastic phase III. With increasing pressure, the range of the superionic phase II expands at the expense of the range of the ferroelastic phase III, which is unstable and vanishes at the triple point. [ABSTRACT FROM AUTHOR]

Some basic problems related to measurements of electrical impedance of biological objects (bioimpedance) have been presented in this paper. Particularly problems arising from impedance occurring at the sensor-tissue interface (interfacial impedances) in contact measuring methods have been discussed. The influence of finite values of impedances of the current source and voltage measuring device has also been taken into consideration. A model of the impedance sensor for the four-electrode measurement method containing the interfacial, source and measuring device impedances has been given and its frequency characteristics obtained by the computer simulation have been presented. The influence of these impedances on the shape of frequency characteristic of the sensor model has been discussed. Measurements of bioimpedance of healthy and anomalous soft tissues have been described. Some experimental results, particularly the frequency characteristics of bioimpedance, have been shown. The presented results of measurement show that bioimpedance can be a valuable source of information about the tissues, so measurement of bioimpedance can be a useful supplement to other medical diagnostic methods. [ABSTRACT FROM AUTHOR]

The Suchedniów water reservoir is located in the central section of the River Kamionka in the northern part of the Holy Cross Mountains of central Poland. This area once belonged to the Old Polish Industrial District that, during the Middle Ages, was very intensively developed by iron metallurgy. Many forges and mills along the rivers used water power, which led to the construction of an anthropogenic, small-scale water retention system. At the beginning of the twentieth century many of these reservoirs were drained after the collapse of metallurgical activities. The present-day reservoir was built in 1974 and drained in 2017. Research into the drained basin has documented various forms and sediments, some of which record present-day depositional processes (fire proof clay layer, inland fan delta), while others represent the historical period (lacustrine sediments of older reservoirs). Traces of catastrophic events have been preserved as well; an assemblage of megaripples marks the sudden drainage caused by a dam break in 1974.

Abstract: Benzimidazolium azelate (abbreviated as BenAze) and benzimidazole (abbreviated as Ben) are generally assumed as model compounds to study a relationship between the hydrogen bond network, molecular dynamics and the electric conductivity process efficiency in an anhydrous system. 1H NMR results correlated with those of proton conductivity and crystal structure have shown that conduction of BenAze crystal is a cooperative process involving both molecular motions prior to the proton exchange and migration along the hydrogen bonded chain. The microscopic model of BenAze conductivity as well as proton transfer path is proposed. It is also shown that efficiency of proton conduction process is limited by restrictions in the motion of benzimidazole molecules. [Copyright &y& Elsevier]