Changes in Electrical Properties of Bulk Ge2Sb2Te5 as a Result of the Crystal–Melt Phase Transition

Molecular mechanisms of gene regulation underlying the activity-dependent long term changes of cellular electrical properties, such as those during memory, are largely unknown. We have shown that alternative splicing can be dynamically regulated in response to membrane depolarization and Ca(2+)/calmodulin-dependent protein kinase IV (CaMKIV) activation, through special CaM kinase responsive RNA elements. However, proteins that mediate this regulation and how they are affected by CaMKIV are not known. Here we show that the regulation of the stress axis-regulated exon of the Slo1 potassium channel transcripts by membrane depolarization requires a highly conserved CaMKIV target serine (Ser-513) of the heterogeneous ribonucleoprotein L. Ser-513 phosphorylation within the RNA recognition motif 4 enhanced heterogeneous ribonucleoprotein L interaction with the CaMKIV-responsive RNA element 1 of stress axis-regulated exon and inhibited binding of the large subunit of the U2 auxiliary factor U2AF65. Both of these activities were abolished by a S513A mutation. Thus, through Ser-513, membrane depolarization/calcium signaling controls a critical spliceosomal assembly step to regulate the variant subunit composition of potassium channels.

A study of the nuclear reactor irradiationinduced changes in the electrical and lattice properties of ferroelectric Pb(Zr0.65Ti0.35)O3+ 1 wt% Nb2O5 revealed that these changes in properties are caused by different damage centers. The changes observed in electrical properties were: (1) Pr decreased but P3 remained constant, (2) double (antiferroelectric‐type) hysteresis loops were formed, (3) an increase by a factor of 5 in grain size did not affect the radiation damage rate in the ceramics, (4) an increase in irradiation temperature of 100°C above room temperature doubled the damage rate, (5) EC for unpoled ceramics was insensitive to irradiation until integrated fast neutron fluxes of lo18 nvt (and the associated γ‐dose) were exceeded and thereafterECincreased exponentially, (6) aging of the radiation‐induced damage did not occur at room tem perature, (7) the damage centers which affected the electric properties were temperature annealed, the annealing temperature depending on the particular material, (8) the introduction of lattice strain, as observed by changes in the longitudinal wave velocity (phonon mean free path length), did not appear to be related to changes in electrical properties. These changes in electrical and thermal properties are consistent with the published data for irradiated triglycine sulfate, Rochelle salt, barium titanate, and guanidinium aluminum sulfate and it is suggested that a common damage model may be constructed for all these ferroelectric materials.

We conducted a fundamental study to elucidate the relationship between acoustic and electrical properties in the context of liver steatosis. The speed of sound, attenuation coefficient, conductivity and relative permittivity were measured in rat livers with varying degrees of fat deposition. Fat deposition results in a decrease in the speed of sound, an increase in the attenuation coefficient and a reduction in conductivity and relative permittivity. However, no linear correlation was observed between these properties and fat content or droplet size individually. However, a notable correlation between changes in acoustic and electrical properties was identified when the structural and organizational effects of fat were considered in combination. In particular, attenuation changes were found to correlate with corresponding changes in electrical properties. These findings underscore the importance of comprehensively considering structural factors, such as fat droplet size and distribution, to better understand the physical mechanisms underlying the relationship between acoustic and electrical properties.

Radio-frequency (RF) has been used to induce ablation and coagulation in liver for minimizing blood loss during liver resection. A multi-level tissue model that we have developed to investigate the changes in electrical properties of liver tissue during RF ablation. The proposed computational model comprises of an equivalent circuit consisting of resistors and capacitors. The potential difference across the cells and the extracellular structure is used to help predicting the associated changes in tissue electrical property. Experiments were done to validate the proposed model and computer simulation. The changes in tissue mechanical properties were correlated with that of electrical property using experiments. Knowledge of tissue properties changes in associated with changes at the cells and the extracellular structure can be used to optimize RF ablation and tissue division during surgery.

In high voltage transformers a liquid dielectric, such as mineral oil, serves both as an electrical insulator (in conjunction with paper) and as a coolant. Similarly, in paper/oil cables mineral oil or dodecylbenzene in conjunction with paper serves as the electrical insulator. In such systems, the oil serves as a convenient medium for sampling to indicate plant health. In the current study dodecylbenzene was aged at elevated temperatures in the presence of air and copper. A battery of tests was then performed to assess the changes in physical, chemical and electrical properties. After aging the oils were yellowed and oils aged with copper showed oxidation, increased water content and the formation of a precipitate, whilst those aged in the absence of copper showed much less aging. Changes in electrical properties were noted such as increased dielectric loss, increased electrical conductivity and decreased dielectric breakdown strength. It was found that the presence of the precipitate did not affect the electrical properties of the oil.

Abnormal conduction and electrocardiographic patterns following myocardial ischemia are related to changes in electrical properties of the myocardium. The local electrical resistivity of the myocardium influences the shape and velocity of the excitation wave [1–3]. The anatomical structure of the myocardium reveals inhomogeneities which may be reflected in its electrical properties. At microscopic level (10–100 µm), the intracellular medium, the extracellular medium, the muscle fiber membrane and the blood containing capillaries all possess distinct electrical properties. At a larger scale (100–1000 µm) the muscle fibers and vasculature are organized such that anisotropic properties can be anticipated. It has indeed been known since Rush’s work [4] that macroscopic (i.e. scale 1–10 mm) resistivity in the muscle fiber direction (ρ l , longitudinal resistivity) is lower than resistivity perpendicular to that direction (ρ t , transverse). Many investigators confirmed this finding, but the reported values for ρ l and ρt vary considerably among authors. First, this variation may be due to different conditions of the preparations. Van Oosterom [5] showed that myocardial resistivity measured transmurally changes dramatically when local ischemia is induced. Wojtczak [6] demonstrated changes in passive electrical properties of cow ventricular muscle with hypoxia. Second, resistivities were studied at different frequencies.

Correlation between changes in morphology, electrical properties, and angiotensin-converting enzyme activity in the failing heart

1. A correlation was established between the changes of internal stresses in three-layer capacitor structures and the change of their electrical parameters. These changes are due to physicochemical processes occurring in films during heat treatment. 2. It was noted that the redistribution of stresses and change of electrical properties is pronounced only at a certain ratio of the thickness of the upper metal plate and insulator film. 3. The changes of internal stresses during annealing in insulator layers are explained by desorption of moisture and in Al films by recrystallization and annealing of defects in newly formed crystallites.

Correlation of physico-chemical, mechanical and electrical properties of ultraviolet-degraded poly(ethylene terephthalate)

Electrical impedance spectroscopy is a well-established tool for monitoring changes in the electrical properties of tissue. Most tissue and organ types have been investigated in various studies. As for the small intestine, there are several published studies conducted on pig and rat models. This study investigates the changes in passive electrical properties of the complete wall of the human intestine non-invasively during ischemia. We aim to use the passive electrical properties to assess intestinal viability. The bioimpedance measurements were performed using a two-electrode set-up with a Solartron 1260 Impedance/gain-phase analyser. The small intestinal samples were resected from patients who underwent pancreaticoduodenectomy. Impedance measurements were conducted following resection by placing the electrodes on the surface of the intestine. A voltage was applied across the intestinal sample and the measured electrical impedance was obtained in the ZPlot software. Impedance data were further fitted into a Cole model to obtain the Cole parameters. The Py value was calculated from the extracted Cole parameters and used to assess the cell membrane integrity, thus evaluate the intestinal viability. Eight small intestinal segments from different patients were used in this study and impedance measurements were performed once an hour for a ten-hour period. One hour after resection, the impedance decreased, then increased the next two hours, before decreasing until the end of the experiment. For all the intestinal segments, the Py values first increased and reached a plateau which lasted for 1 - 2 hours, before it decreased irreversibly. The time interval where Py value reached the maximum is consistent with reported viable/non-viable limits from histological analysis.

1. This study was undertaken to investigate the effects of adriamycin (ADM, Doxorubicin) on the basic electrophysiological properties of spinal cord motoneurons in the adult cat. ADM was injected into the biceps, gastrocnemius, semitendinosus, and semimembranosus muscles of the left hindlimb (1.2 mg per muscle). Intracellular recordings from motoneurons innervating these muscles were carried out 12, 20, or 40 days after ADM administration and from corresponding motoneurons in untreated control cats. 2. Twelve days after ADM injection, motoneurons innervating ADM-treated muscles (ADM MNs) exhibited statistically significant increases in input resistance, membrane time constant, and amplitude of the action potential's afterhyperpolarization (AHP). In addition, there was a statistically significant decrease in rheobase and in the delay between the action potential of the initial segment (IS) and that of the somadendritic (SD) portion of the motoneuron (IS-SD delay). There were no significant changes in the resting membrane potential, threshold depolarization, action potential amplitude, or axonal conduction velocity. 3. The changes in electrical properties of motoneurons at 20 and 40 days after ADM injection were qualitatively similar to those observed at 12 days. However, at 40 days after ADM injection there was a statistically significant decrease in the axonal conduction velocity of the ADM MNs. 4. The normal correlations that are present between the AHP duration and electrical properties of the control motoneurons were observed in the ADM MNs, e.g., AHP duration was positively correlated with the input resistance and time constant and negatively correlated with the axonal conduction velocity. The correlation coefficients, however, were reduced in comparison with the control data. 5. This study demonstrates that ADM exerts significant effects on the electrical properties of motoneurons when injected into their target muscles. The majority of the changes in motoneuron electrical properties caused by ADM resemble those observed in motoneurons of aged cats. Additional research is required to determine whether the specific changes induced in motoneurons by ADM and those that occur in motoneurons in old age are due to similar degradative mechanisms.

Direct electrical detection of hybridization at DNA-modified silicon surfaces

Electrical and acoustic vibroscopic measurements for determining carbon nanotube fiber linear density

Gangliosides, glycolipids that are abundant in the plasma membrane outer leaflet, play an integral role in cellular recognition, adhesion, and infection by interacting with different endogenous molecules, viruses, and toxins. Model membrane systems, such as ganglioside-enriched supported lipid bilayers (SLBs), present a useful tool for sensing, characterizing, and quantifying such interactions. In this work, we report the formation of ganglioside GM1-rich SLBs on conducting polymer electrodes using a solvent-assisted lipid bilayer assembly method to investigate changes in membrane electrical properties upon binding of the B subunit of cholera toxin. The sensing capabilities of our platform were investigated by varying both the receptor and the toxin concentrations in the system as well as using a complex sample (milk contaminated with the toxin) and monitoring the changes in the electrical properties of the membrane. Our work highlights the potential of such conducting polymer-supported biomembrane-based platforms for detecting the toxins within a complex environment, studying ganglioside-specific biomolecular interactions with toxins and screening inhibitory molecules to prevent these interactions.

The effect of UV irradiation on ZnO thin film based gas sensor was investigated. Zinc oxide thin films were deposited on an alkali free glass substrate by magnetron sputtering system using zinc target. The UV irradiation of the ZnO thin films was measured to understand the change of microstructure, electrical properties, optical properties and gas sensing characteristics. The X-ray diffraction patterns and SEM images revealed that the films have a nanocrystalline structure. The optical properties of ZnO films were not affected by the UV irradiation significantly. The gas sensing behavior of zinc oxide thin films were enhanced by UV irradiation for a shorter period whereas sensing characteristics were degraded for a longer irradiation period. It was also observed that the dependence of gas sensing characteristics was correlated with the change of electrical properties and crystallinity of films.