Conformational transition in aqueous solution of poly(L-glutamic acid): a low-frequency electrical conductivity study

1992 ◽  
Vol 96 (2) ◽  
pp. 913-918 ◽  
Author(s):  
F. Bordi ◽  
C. Cametti ◽  
G. Paradossi
Keyword(s):  
Aqueous Solution ◽  
Electrical Conductivity ◽  
Glutamic Acid ◽  
Conformational Transition ◽  
Low Frequency ◽  
Electrical Conductivity Study

Conformational transition of poly(L-glutamic acid) in aqueous solution

Biopolymers ◽  
1966 ◽  
Vol 4 (5) ◽  
pp. 529-538 ◽  
Author(s):  
G. Barone ◽  
V. Crescenzi ◽  
F. Quadrifoglio
Keyword(s):  
Aqueous Solution ◽  
Glutamic Acid ◽  
Conformational Transition

Radio and Electrical Measurements on Glacial Streams

1987 ◽  
Vol 33 (114) ◽  
pp. 239-242
Author(s):  
M. E. R. Walford
Keyword(s):  
Electrical Conductivity ◽  
Water Channel ◽  
Water System ◽  
Low Frequency ◽  
Water Channels ◽  
Radiative Loss ◽  
Radio Waves ◽  
Electrical Measurements ◽  
Water Conductivity ◽  
Glacier Surface

AbstractWe discuss the suggestion that small underwater transmitters might be used to illuminate the interior of major englacial water channels with radio waves. Once launched, the radio waves would naturally tend to be guided along the channels until attenuated by absorption and by radiative loss. Receivers placed within the channels or at the glacier surface could be used to detect the signals. They would provide valuable information about the connectivity of the water system. The electrical conductivity of the water is of crucial importance. A surface stream on Storglaciären, in Sweden, was found, using a low-frequency technique, to have a conductivity of approximately 4 × 10−4 S m−1. Although this is several hundred times higher than the conductivity of the surrounding glacier ice, the contrast is not sufficient to permit us simply to use electrical conductivity measurements to establish the connectivity of englacial water channels. However, the water conductivity is sufficiently small that, under favourable circumstances, radio signals should be detectable after travelling as much as a few hundred metres along an englacial water channel. In a preliminary field experiment, we demonstrated semi quantitatively that radio waves do indeed propagate as expected, at least in surface streams. We conclude that under-water radio transmitters could be of real practical value in the study of the englacial water system, provided that sufficiently robust devices can be constructed. In a subglacial channel, however, we expect the radio range would be much smaller, the environment much harsher, and the technique of less practical value.

scholarly journals Broadband dielectric spectroscopy for monitoring temperature-dependent chloride ion motion in BiOCl plates

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Adrian Radoń ◽  
Dariusz Łukowiec ◽  
Patryk Włodarczyk
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Spectroscopy ◽  
Low Frequency ◽  
Chloride Ion ◽  
Ion Source ◽  
Chloride Ions ◽  
Ion Concentration ◽  
Broadband Dielectric Spectroscopy ◽  
Free Chloride ◽  
Structure Rebuilding

AbstractThe dielectric properties and electrical conduction mechanism of bismuth oxychloride (BiOCl) plates synthesized using chloramine-T as the chloride ion source were investigated. Thermally-activated structure rebuilding was monitored using broadband dielectric spectroscopy, which showed that the onset temperature of this process was 283 K. This rebuilding was related to the introduction of free chloride ions into [Bi2O2]2+ layers and their growth, which increased the intensity of the (101) diffraction peak. The electrical conductivity and dielectric permittivity were related to the movement of chloride ions between plates (in the low-frequency region), the interplanar motion of Cl− ions at higher frequencies, vibrations of these ions, and charge carrier hopping at frequencies above 10 kHz. The influence of the free chloride ion concentration on the electrical conductivity was also described. Structure rebuilding was associated with a lower concentration of free chloride ions, which significantly decreased the conductivity. According to the analysis, the BiOCl plate conductivity was related to the movement of Cl− ions, not electrons.

Investigating the dielectric properties and low-frequency relaxation process of TlGaSe2 crystals

2017 ◽  
Vol 31 (12) ◽  
pp. 1750134 ◽  
Author(s):  
Oktay Samadov ◽  
Oktay Alakbarov ◽  
Arzu Najafov ◽  
Samir Samadov ◽  
Nizami Mehdiyev ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Relaxation Time ◽  
Constant Electric Field ◽  
Low Frequency ◽  
Constant Field ◽  
Impedance Spectra ◽  
Ionic Contribution ◽  
Frequency Relaxation ◽  
Average Relaxation Time ◽  
Diagram Analysis

The dielectric and impedance spectra of TlGaSe2 crystals have been studied at temperatures in the 100–500 K range in the alternating current (AC [Formula: see text]1 V). It has been shown that the conductivity of TlGaSe2 crystals is mainly an ionic characteristic at temperatures above 400 K. The well-defined peak at the frequency dependence of the imaginary part of impedance [Formula: see text] is observed in the 215–500 K temperature range. In a constant field, there occurs a significant decrease in electrical conductivity [Formula: see text] in due course. The ionic contribution to conductivity (76% at [Formula: see text]) has been estimated from a kinetic change in electrical conductivity [Formula: see text] under the influence of a constant electric field. The diagram analysis in a complex plane [Formula: see text] has been conducted by applying the method of an equivalent circuit of the substation. It has been determined that the average relaxation time of the electric module of the sample is [Formula: see text].

scholarly journals Concentration-dependent conformational transition of alpha-elastin in aqueous solution.

1978 ◽  
Vol 253 (9) ◽  
pp. 2893-2894
Author(s):  
A.M. Tamburro ◽  
V. Guantieri ◽  
D. Daga-Gordini ◽  
G. Abatangelo
Keyword(s):  
Aqueous Solution ◽  
Conformational Transition

scholarly journals Impact of external physical effects on water and aqueous solutions: the problem of “memory”

2019 ◽  
Vol 59 (7) ◽  
pp. 1-16
Author(s):  
Ksenia A. Nurislamova ◽  
◽  
Alena S. Franz ◽  
Vyacheslav F. Markov ◽  
Larisa N. Maskaeva ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Electrical Conductivity ◽  
Aqueous Solutions ◽  
Solid Phase ◽  
Cluster Structure ◽  
Lead Salt ◽  
Physical Factors ◽  
Scientific Publications ◽  
Physical Effects ◽  
The Impact

A brief analysis of scientific publications on the changes in the physicochemical properties of water and aqueous solutions under the influence of temperature, magnetic and electric fields, laser and microwave radiation, ultrasound, and mechanical mixing was performed. A number of researchers have shown the influence of such effects on changes in pH and redox potential, electrical conductivity, surface tension and viscosity of an aqueous solution. The question of influence of external physical effects on water and aqueous solutions remains controversial. Some scientists suggest that water has a cluster structure, which is influenced by physical effects. An important aspect of the problem is the impact on the subsequent behavior and the final result of a chemical process involving previously treated aqueous solutions. Using water solutions of lead and thiourea as an example, the effect of their temperature prehistory in the range of 275-369 K on the kinetics of precipitation of the solid phase of lead sulfide and their microstructure is demonstrated. A threefold change in the composition of supersaturated CdxPb1–xS solid solutions precipitated from solutions containing a lead salt with different temperature prehistory was established. It is shown that the “memory” on the preliminary temperature effect is maintained for at least a day. The influence of electromagnetic treatment of water and aqueous solutions on the content of dissolved oxygen, pH and electrical conductivity is analyzed. Some scientists explain these results by the influence of the field on the structure of hydrogen bonds, others by a change in the cluster structure of water, as well as by the presence of ferromagnetic particles in water. The review presents the current state of the problem of the “memory” effect and the related influence of the prehistory of the impact of physical factors. The review suggested that the “memory” of an aqueous solution is the preservation for a certain time of the changes in its structure and properties that have arisen as a result of the effect. The basic ideas about the mechanisms of influence of the prehistory of physical effects on aqueous solutions are given.

scholarly journals Specialties of the structure and conductivity of the non-aqueous electrolytes based on alkali metal bis (salicyl) borates and bis (oxalate) borates

2019 ◽  
Vol 85 (3) ◽  
pp. 49-55
Author(s):  
Viktor Diamant ◽  
Volodymyr Trachevskii ◽  
Katherine Pershina ◽  
Volodymyr Ogenko ◽  
Chen Donchu ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Alkali Metals ◽  
Electrochemical Impedance ◽  
Integral Intensity ◽  
Low Frequency ◽  
Aqueous Electrolytes ◽  
Thermal Dependence ◽  
Spectra Analysis ◽  
Reactive Medium ◽  
Coordination Environment

The structure and coordination environment of non-aqueous electrolytes based on bis(salicyl)borates of lithium, sodium, potassium, tetramethylammonium (MeBSB) and bis(oxalato)borates from lithium to cesium (MeBOB) using NMR spectroscopy have been investigated. Bis(salicyl)borates (BSB) and bis(oxalate)borates (BOB) of alkali metals and organic cations are considered as promising electroconductive components of electrolytes of modern chemical sources of current (lithium, sodium ion batteries and super-capacitors). The salts were synthesized by the microwave radiation method. The 13C and 11B NMR spectra analysis determined the presence of symmetric structure in BOB anion and the presence of two optical conformations of the BSB anion with labile coordination environment of boron. The conformations of the BSB are the result of the ion contact pairs formation. In the case of tetramethylammonium cation the presence of conformations are depended on the reactive medium. The conformational lability of the coordination sphere of NaBSB dissolved in DMAA is connected with increasing of the integral intensity of carboxyl group singles relatively signals of carbon atoms in fragments of another functional affiliation when the time delay between radio frequencies varies within 2-15 seconds. The difference in the structure of these anions leads to a change in the thermal dependence of the electrical conductivity of BSB and the transport of ions in non-aqueous solvents. Maximum electrical conductivity of salt solutions in DMFA is achieved at close concentrations of 0.75 m for KBSB and 0.77-1 m for NaBSB. The solubility of BSB is better than the BOB. Based on the measurements of the conductivity and the data of electrochemical impedance spectroscopy (the angle of inclination of spectra in the Nyquist coordinates in the low frequency range, the phase angle shift at a frequency) it was proposed the existence of two ways of ions and charge transfer in the electrolytes: diffusion and relay transport. The possibility of formation of a labile salt complex with a solvent due to hydrogen bonds is established.  

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