Specific Electrical Conductivity Research Articles

Specific Electric Conductivity and Electrokinetic Potential of Porous Glasses of Different Compositions in Solutions of 1 : 1-Charged Electrolytes at a Constant Salt Level

Specific Electric Conductivity and Electrokinetic Potential of Porous Glasses of Different Compositions in Solutions of 1 : 1-Charged Electrolytes at a Constant Salt Level

Electric arc in plasma flow of gas discharge with a liquid electrolyte

The properties of an electric arc ignited in a gas discharge plasma flow with a liquid electrolyte cathode are experimentally investigated. Aqueous solutions of sodium chloride with a specific electrical conductivity of 10-15 mS/cm were used as a liquid electrolyte. The distance between the anode and the liquid electrolyte cathode was set in the range of 5-60 mm, and the distance between the anode and the metal cathode was varied in the range of 2-30 mm. The current of gas discharge with a liquid electrolyte cathode was set in the range of 5-10 A, and the arc current varied in the range of 1-10 A. The conditions under which the arc burns with the formation of a contracted channel are revealed.

Combined electric discharge “arc + discharge with liquid electrolyte cathode”

A combination of an electric arc and discharge with a liquid electrolyte cathode in a single discharge gap has been created. The plasma column of discharge with liquid electrolyte cathode formed a “hollow cylinder”. The electric arc was burned in a vapor-gas environment inside the “hollow cylinder”. The gas discharge current with liquid electrolyte cathode was set in the range of 5-10 A, and the arc current varied in the range of 1-10 A. Aqueous solutions of sodium chloride with a specific electrical conductivity of 10-15 mS/cm were used as a liquid electrolyte. Spectral studies have been carried out in the visible range of radiation. In the experiments, copper and duralumin metal cathodes were used.

Copper-Carbon Nanotubes Composite Materials for Lightning Strike Protections in Airplanes

The structures of airplanes are nowadays including more and more non electrically conductive plastics parts. To mitigate the damages after lightning strike events, copper meshes are integrated into the fuselage to provide it with electrical conductivity. Yet, although copper has one of the best electrical and thermal conductivities, its density remains high compared to materials like Aluminium (8.96 g.m-3 for Copper ; 2.7 g-m-3 for Aluminium) and R&D efforts are needed to develop new materials with higher specific electrical conductivity and ampacity. In 2013, Subramaniam et al.1 reported the fabrication of Copper/Carbon nanotubes (Cu-CNTs) composites with a similar specific conductivity than the one of copper and an ampacity increased by two orders of magnitude.The talks will describe an original fabrication method of Cu-CNTs composites based on electroplating and entirely realized without any hazardous organic solvents. Their electrical behaviour (conductivity as well as ampacity) will be described as well as a first evaluation of their lightning strike protection (LSP) properties. The lightning strike damages observed on pristine and Cu-CNTs samples consist of concentric vaporized zones more or less extended depending of samples. Interestingly, for some Cu-CNTs composites, partial or no vaporization is observed with a preserved electrical conductivity of the samples.Subramaniam, C., Yamada, T., Kobashi, K. et al. One hundred fold increase in current carrying capacity in a carbon nanotube–copper composite. Nat Commun 4, 2202 (2013).

Synthesis, aggregation, and biocidal properties of N-2-hydroxypropyl piperidine based cationic surfactants

New cationic ionic liquid surfactants (ILS) based on (C9-C10, C12 and C14) alkyl bromides and N-2-hydroxypropyl piperidine have been synthesized. Colloidal parameters of aqueous solutions of the obtained ILSs were studied by surface tension and dynamic light scattering methods. Specific electrical conductivity was measured by the conductometric method. Depending on the alkyl chain length, critical micelle concentration (CMC), maximum adsorption (Гmax), the minimum cross-sectional area of the surfactant polar group (Amin), adsorption efficiency (pC20), surface pressure (πCMC), degree of counterion binding (β), changes of the Gibbs free energy of micellization and adsorption (ΔGmic and ΔGad) were studied. The ILSs antimicrobial properties were tested on various bacteria and fungi.

Modifying Ti3C2 MXene with NH4+ as an excellent anode material for improving the performance of microbial fuel cells

Poor anode performance is one of the main bottlenecks in the development of microbial fuel cells (MFCs) for practical applications. Multilayered Ti3C2 MXene (m-MXene) is an alternative anode modification material because of its high specific surface area and electrical conductivity. However, the multilayered structure, negatively charged surface, and electropositivity of m-MXene could limit its modification effects. In this work, we used a solution-phase flocculation method (ammonium ion method) to restack and aggregate MXene nanosheets as an anode modification material (n-MXene). The n-MXene-modified anode had a higher specific surface area, surface hydrophilicity and surface electropositivity than the m-MXene-modified anode. The n-MXene-modified anode obtained a maximum current density of 2.1 A m−2, which was 31.2% and 61.5% higher than that of the m-MXene-modified anode (1.6 A m−2) and bare carbon fiber cloth anode (1.3 A m−2). This improved anode performance was attributed to both the decrease in the charge transfer resistance and diffusion resistance, which were related to the increased quantity of biomass and microbial nanowire (or pili)-shaped filaments on the electrode surface. This work provides a simple and cost-effective approach to prepare MXene nanosheets for the modification of MFC anodes.

Ultrathin MoSe2 nanosheets decorated on carbon aerogel microspheres for high-capacity supercapacitor electrodes

A new MoSe 2 /CRF electrode was successfully constructed, which possessed enhanced specific capacitance and high cycling stability via the synergistic effect of MoSe 2 nanosheets and carbon aerogel microspheres. • MoSe 2 nanosheets and carbon aerogel microspheres hybrid via solvent-thermal method was prepared. • MoSe 2 NSs/CRF electrode exhibits an excellent specific capacitance and a high cycling stability. • Porous carbon aerogel microspheres restrict the aggregation of MoSe 2 nanosheets. • MoSe 2 NSs/CRF has potential as an electrode material in supercapacitor fields. Two-dimensional layered molybdenum selenide nanosheets have been a promising electrode material for electrochemical energy storage because of their high theoretical capacitance. However, the intrinsic low electrical conductivity and inferior structural stability impede its real application. Herein, MoSe 2 nanosheets are incorporated into carbon aerogel microspheres (MoSe 2 NSs/CRF) via a facile solvent-thermal method. The specific surface area and electric conductivity of the MoSe 2 NSs/CRF electrode were increased simultaneously because of its incorporation with porous carbon aerogel microspheres. As a result, the MoSe 2 NSs/CRF electrode exhibits an excellent specific capacitance of 498F g −1 at a current density of 1 A g −1 , which is 3 times higher than that (136F g −1 ) of the pristine MoSe 2 nanosheets. With a 5-fold increase to 5 A g −1 , it still retains 278F g -1 and high cycling stability of 127.2% of the initial retention after 2500 cycles at 100 mV s −1 . Moreover, we fabricated a symmetric supercapacitor (SC) using a composite composed of MoSe 2 NSs/CRF. The symmetric supercapacitor showed capacitance of 124F g −1 with an energy density of 8.5 W h Kg −1 at a power density of 264.8 W Kg −1 at a current density of 1 A g −1 . The superior electrochemical performances demonstrating that the MoSe 2 NSs/CRF has potential as an electrode material for energy storage application in high-performance supercapacitor fields.

Unveiling the role of oxidative treatments on the electrochemical performance of carbon nanotube-based cotton textile supercapacitors

Herein, all-solid-state textile supercapacitors (TSCs) were produced using a cost-effective readily-available natural fabric as substrate (cotton) and different types of oxidized multiwalled carbon nanotubes (MWCNTs) as electrode nanomaterials. The MWCNT oxidative treatments were performed using three agents, HNO3, H2SO4 and HNO3/H2SO4, to unveil their role on the performance and energy storage mechanism of the resulting TSCs. The TSCs based on the oxidized MWCNTs exhibited up to 106% enhanced energy density than the device based on pristine MWCNTs (up to 3.48 W h kg−1 vs. 1.69 W h kg−1) and up to 98% capacitance retention over 5000 cycles. A balance between the extent of oxidation of the MWCNTs, their specific surface area and electrical conductivity was required to boost the performance. The MWCNT oxidation with HNO3 promoted the highest increase of the specific surface area, the creation of redox-active surface oxygen-based groups and optimum surface oxygen loading (4.0%). The synergy between these features endowed a pseudocapacitive contribution to the energy storage mechanism, leading to the TSC with the best performance. This work constitutes a breakthrough on the rational design of easily scalable TSCs directly produced on natural non-conductive substrates using tuned oxidized MWCNT electrode nanomaterials to meet the demands of the thriving Era of wearable electronics.

Sources of stream base flow in blanket peat covered catchments

A two year hydrological characterisation programme of relatively intact blanket peat-covered catchments, underlain by geochemically distinct substrates, investigated the influence of sub-peat materials on the runoff regimes of the first order and second order streams draining them. Semi-continuous monitoring of flow and water quality revealed a strong inverse relationship between stream flow rates and specific electrical conductance (SEC), with runoff chemistries during storm flow proving comparable in all three catchments. By contrast, differences in water quality between catchments became more pronounced at lower flow, where increased ion concentrations in stream water reflected reactions with peat substrate materials. Water table monitoring in peat at all three sites revealed groundwater levels to vary by less than 0.6 m over the investigation period. Findings suggest runoff consists of near constant inputs of higher specific electrical conductance peat substrate discharge, mixing with variable proportions of less mineralised and more compositionally variable bog water. Although making up less than 5% to total runoff, the contribution of more mineralised waters plays an important role in maintaining stream flow, particularly during prolonged dry periods, and may help explain the aquatic biodiversity encountered in blanket peat covered areas.

Effect of water activated by non-equilibrium gas-discharge plasma on the germination and early growth of cucumbers

The article presents the results of plasma-chemical treatment of water and studies of its effect on the germination of cucumber seeds, as well as on the dynamics of the initial growth of 
 plants. Tap water was treated with a pulsed underwater discharge formed in vapor-gas bubbles near the surface of a graphite electrode immersed in water. The discharge burned at peak voltage values of 800 V and a discharge current of 200 mA. Oscillograms of the current and voltage on the electrodes were obtained, the values of the specific electrical conductivity of water, the pH value, the concentrations of nitrite and nitrate ions, and also hydrogen peroxide in the treated water were measured. It is shown that the application of the plasma treated water ncreases the seed germination, accelerates the development of the root system, the growth of stem and leaves at the early stages of plant development

Influence of Sulphate Attack on Properties of Modified Cement Composites

Monitoring the condition of building structures based on composite materials in aggressive environments shows that the deterioration of basic properties occurs under the influence of various factors such as temperature and humidity changes, in addition to changes in the chemical composition of air environment. In addition, the composite materials during the operation must retain not only the mechanical properties laid down at the design stage, but also the electro-physical characteristics, regardless of the type of destructive effects. In the current study, the quantitative assessment of the result of the interaction of an aggressive sulphate-containing medium with composites modified with conductive and dielectric additives was carried out. The effect of sulphate attack on the specific electrical conductivity of cement composites was studied. The nature of the interaction was evaluated by changing the properties of the samples of the developed compositions under the influence of a single-normal solution of sodium sulphate. The analysis was carried out by means of potentiometric titration using the exchange interaction method by fixing the degree of absorption of sulphate ions and determining the concentration of calcium ions in the solution. The measurement of the solution potential allowed determination of the quantitative indicators of the rate of calcium hydroxide leaching from the sample structure, which is necessary to assess the intensity of the destruction process and determine the nature of the change in strength properties. Measurements of the electrical resistivity of samples under the constant influence of sulphate aggression were taken during 28 days of observation. A method for quantifying the effect of a sulphate medium on a cement matrix was proposed that enables the material durability to be predicted. The features of changes in the morphology of structural components after exposure to aggressive solution were determined by physical and chemical methods.

Adaptation of wheat varieties under combined stress

The article presents the results of studies of adaptive reactions of 10-day-old seedlings of wheat varieties Novosibirskaya 18, Novosibirskaya 44, Sibirskaya 21 and Omskaya 18 under combined stress. The indices of growth, accumulation of wet and dry biomass and permeability of cell membranes by specific electrical conductivity (EC) of leaf extracts under the combined action of chloride salinity (1.3%) and hyperthermia of seeds (43 °C) were studied. Chloride salinization without preliminary heating of seeds caused mainly a decrease in adaptive capacity and a loss of cultivar resistance (a decrease in growth to 57.2%, a decrease in biomass to 35.2%, an increase in EC up to 5.7 times). The most resistant cultivar is Omskaya 18. Preliminary hyperthermia of seeds increased the resistance of seedlings to the subsequent action of chloride salinization (decrease in EC to 56.2%, inhibition of biomass accumulation and growth by up to 14 times). The protective effect of hyperthermia during the subsequent action of salinity is most pronounced in the Sibirskaya 21 variety.

N-doped reduced graphene oxide/Co0.85Se microflowers with high mass loading as battery-type materials for quasi-solid-state hybrid supercapacitors

In this work, we prepared N-doped reduced graphene oxide/Co0.85Se (N-rGO/CS) microflowers through a two-step method. Since introducing N-doped rGO, the fabricated N-rGO/CS electrode with a high mass loading (~8.83 mg/cm2) exhibits high areal specific capacity of 0.522 mAh/cm2 (4.24 F/cm2) at 1 mA/cm2, and a long-term cycling stability (85.8% of capacity retention after 6000 charge-discharge cycles). This is mainly because N-doped rGO can increase specific area and electrical conductivity, enhance the electrochemical activity and effectively facilitate the electron/ion transport between the electrode and electrolyte. Besides, the quasi-solid-state hybrid supercapacitors (HSCs) assembled by the N-rGO/CS delivers a high volumetric specific capacity of 5.82 mAh/cm3 at 1 mA/cm2, excellent energy density of 4.65 mWh/cm3 under 10.5 mW/cm3 and eminement cycle stability (87.6% retention over 6000 cycles at 10 mA/cm2).

Are aerosols on the leaves of apricot trees (Prunus armeniaca) signalizing the activity of a hidden paleo-supervolcano in a steppe?

Aerosols on plant leaves make it possible to assess the quality of air in settlements. The purpose of this work was to assess the acidity and specific electrical conductivity of aerosol suspensions (by washing off aerosol particles from the leaves of apricot trees (Prunus armeniaca)), which characterize the air pollution in the residential area of the Svetly Yar settlement (Volgograd region, Russia) during the spring-summer of 2019. The research hypothesis was as follows: Acidic mineralized aerosols with a mixed source are present in Svetly Yar. The differences were checked by the Student's t-test and evaluated at the level of significance of p = 0.05. The results indicated the presence of acidic (pH = 4.56 + 0.02) and highly mineralized aerosols (EC = 130.41 + 0.17 μS/cm) in the ambient air of the Svetly Yar residential area during the spring-summer of 2019 and revealed environmental risks for the population in comparison with aerosol suspensions from a (relatively) clean location (pH = 6.46 + 0.02; EC = 37.61 + 0.19 μS/cm). The authors confirmed their hypothesis in favor of mixed source acidic mineralized aerosols in the residential area of the Svetly Yar village. The anthropogenic sources were the industrial zones of Svetly Yar, the southern part of the city of Volgograd and artificial sedimentation tanks in the southwestern part of Svetly Yar. A natural source of pollution in the vicinity of Svetly Yar may be hidden geologically active structures: faults in the Earth's crust, a salt diapir, an underground ancient semiactive volcanic zone on a steppe, etc.

Laser Technology for the Formation of Bioelectronic Nanocomposites Based on Single-Walled Carbon Nanotubes and Proteins with Different Structures, Electrical Conductivity and Biocompatibility

A laser technology for creating nanocomposites from alternating layers of albumin/collagen proteins with two types of single-walled carbon nanotubes (SWCNT) at concentrations of 0.001 and 0.01 wt.% was proposed. For this purpose, a setup with a diode laser (810 nm) and feedback system for controlling the temperature of the area affected by the radiation was developed. Raman spectroscopy was used to determine a decrease in the defectiveness of SWCNT with an increase in their concentration in the nanocomposite due to the formation of branched 3D networks with covalent bonds between nanotubes. It was revealed that adhesion of proteins to branched 3D networks from SWCNT occurred. The specific electrical conductivity of nanocomposites based on large SWCNT nanotubes was 3.2 and 4.3 S/m compared to that for nanocomposites based on small SWCNT with the same concentrations—1.1 and 1.8 S/m. An increase in the concentration and size of nanotubes provides higher porosity of nanocomposites. For small SWCNT-based nanocomposites, a significant number of mesopores up to 50 nm in size and the largest specific surface area and specific pore volume were found. Nanocomposites with small SWCNT (0.001 wt.%) provided the best cardiac fibroblast viability. Such technology can be potentially used to create bioelectronic components or scaffolds for heart tissue engineering.

Size-refinement enhanced flexibility and electrochemical performance of MXene electrodes for flexible waterproof supercapacitors

Increasing mechanical flexibility without sacrificing electrochemical performance of the electrode material is highly desired in the design of flexible electrochemical energy storage devices. In metal-related materials science, decreasing the grain size introduces more grain boundaries; this stops dislocations and crack propagation under deformation, and results in increased strength and toughness. However, such a size refinement effect has not been considered in the mechanical properties, particle stacking, wetting, and electrochemical performances of flexible supercapacitor electrodes. In this paper, MXene was used as an electrode material to study the size refinement effect of flexible supercapacitors. Size refinement improved the strength and toughness of the MXene electrodes, and this resulted in increased flexibility. Finite elemental analysis provided a theoretical understanding of size refinement-increased flexibility. Moreover, the size refinement also improved the specific surface area, electric conductance, ion transportation, and water wetting properties of the electrode, and the size refinement provided highly increased energy density and power density of the MXene supercapacitors. A highly flexible, water-proof supercapacitor was fabricated using size-refined MXene. The current study provides a new viewpoint for designing tough and flexible energy storage electrodes. The size refinement effect may also be applicable for metal ion batteries and electronic and photo devices composed of MXene and other nanoparticles.

Carbon nanotube fibers with high specific electrical conductivity: Synergistic effect of heteroatom doping and densification

Low contact resistance of carbon nanotube (CNT) fibers are fundamental component to improve the electrical transport properties of CNT fibers. To reduce the contact resistance of CNT fibers, we have demonstrated synergistic effect of macroscopic densification in combination with heteroatom doping. Boron and nitrogen atoms were introduced into the hexagonal carbon lattice of the CNTs through judicious combination of high temperature thermal doping and plasma treatment. Chlorosulfonic acid (CSA) was chosen to provide selectively quaternary nitrogen on the sidewall of the CNTs. During this process, densification of the CNT fibers also proceeded, and consequently reduced the hopping or tunneling distance for inter-CNT electron transfer. As a result, we achieved remarkable electrical conductivity of the CNT fibers as high as 5,896 Sm2/kg. The mechanism study by which heterogeneous conduction model proved the decrease of the electrical barrier height of the CNT fibers. These results provide a substantial step towards the use of CNT fibers as conductive materials.

Energy efficiency and physical integrity of maize grains subjected to continuous and intermittent drying

ABSTRACT Grain drying is a common process, due to its need for the maintenance of quality, but it is the activity with the highest energy demand among the postharvest stages. Thus, this study aimed to evaluate the effect of different tempering times on the energy efficiency of drying process and maintenance of cell membrane integrity of maize grains harvested with moisture content at 0.34 ± 0.01 d.b. The grains were dried in an experimental fixed-bed dryer with control of temperature and air flow conditions. The experiment was conducted in a completely randomized design with five tempering times (0, 4, 8, 12 and 16 hours) and four repetitions, where zero corresponds to continuous drying, while the remaining times correspond to the intermittent dryings. The grains were dried at the temperature of 100 ºC and air flow of 15.4 m3 min-1 t-1 until reaching moisture content of 0.16 ± 0.03 d.b. For intermittent drying, the process was interrupted with 0.22 ± 0.02 d.b. and restarted after the tempering time. The increase of tempering time led to reductions in effective drying time, specific energy consumption, electrical conductivity and damage and increase in the drying rate and overall energy efficiency. Intermittent drying reduced the drying time, being 30.25% more efficient than continuous drying.

Comparative Analysis of Methods for Mathematical Modeling of Specific Electrical Conductivity of Plasma in the Channel of an Electric Discharge in Water

In the present work, a comparative analysis of three methods for determining the specific electrical conductivity of the plasma formed in the channel of an electric discharge in water is carried out for its mathematical modeling. The parameters of the empirical function are determined, at which the results of mathematical modeling are consistent with the experimental data. The necessity of using empirical functions in calculating the specific electrical conductivity of plasma has been substantiated. The obtained ratios made it possible to significantly increase the adequacy of the previously developed mathematical model of the physical discharge processes in water and to expand the range of parameters in which it can be used.

The indicator of cell membrane permeability of wheat seedlings in assessing stress resistance of wheat varieties

The paper presents the results of studies on the use of the permeability index of cell membranes, determined by the relative change in the specific electrical conductivity (EC) of water extracts of tissues of spring wheat seedlings, varieties Novosibirskaya 18, Novosibirskaya 44, Sibirskaya 21 and Omskaya 18, under the combined action of stressors. In model laboratory vegetation experiments, the hourly dynamics of the EC of water extracts of seedling leaves (exposure of leaves to water for 0.5-4.5 h) was investigated under the simultaneous action of chloride salinity (1.3%) and the causative agent of common rot of cerealsBipolaris sorokinianaShoem. (5000 conidia per grain). It was established that EC increased by 1.5 times and the rate of electrolyte leakage increased twofold in the less resistant variety Novosibirskaya 44 compared to the more resistant Omskaya 18. The daily dynamics of the EC of 10-16-day-old seedlings was studied under the sequential action of seed hyperthermia (43 °C), chloride salinity (1.3%), andBipolaris sorokinianaShoem. (5000 conidia per grain). The protective effect of hyperthermia was established in the more resistant variety Sibirskaya 21 (a decrease in EC up to 1.3 times) in comparison with the variant without heating the seeds. In the less resistant variety Novosibirskaya 18, heating the seeds destabilized the state of the cell membranes (increase in EC and electrolyte leakage rate by 1.5 and 1.2 times respectively). The conditions that ensure the identification of the maximum differences in the studied wheat varieties were experimentally determined: the age of seedlings 10 days, the time interval of exposure of the samples to water 1.5-4.5 h. Intervarietal differences in the relative change in the EC values in the variant without heating the seeds were 1.9 times and in the variant with heating the seeds - 3.7 times, with the significance of difference at the levelsp≤ 0.05 andp≤ 0.01. Intervarietal differences in the relative change in the EC, established for the time interval exposition of electrolytes leakage of 1.5-4.5 h, were 1.50-1.67 times with the significance of difference at the level ofp≤ 0.05. The proposed approach will make it possible to develop a methodology for assessing new genotypes for resistance to the combined action of biotic and abiotic stressors.