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Abstract The magnetization value and electric resistivity of the single-crystalline sample of Ni50Fe19Co4Ga27 shape memory alloy were measured. The elastic modulus was determined by the Dynamic Mechanical Analysis (DMA). The characteristic temperatures of martensitic transformation (MT) of the alloy were estimated from the temperature dependences of magnetization, electric resistivity and elastic modulus. A significant disparity between MT temperatures resulting from DMA and those estimated from magnetic and resistivity measurements was discovered. It was argued that the discrepancy is caused by the non-uniform mechanical stressing of twinned single crystal by the DMA analyzer. Moreover, the DMA measurements revealed a significant decrease of the elastic modulus of twinned martensite under the applied magnetic field of 1.5 kOe. To explain this effect, the temperature-dependent Young’s modulus of twinned crystal lattice was computed. The computations showed that the experimentally observed field-induced change of the elastic modulus is caused by the stress-assisted detwinning of the crystal lattice by the applied magnetic field.

The 16MnCr5 alloy steel samples are evaluated in a normalized condition and put through low cycle fatigue (LCF) under constant amplitude strains of εa = 0.2%, 0.25%, 0.4%, and 0.6%. Mechanical properties are reported based on the LCF results. Fatigue damage is checked in specimens that have reached 80% of their nominal fatigue life by two methods that are different from traditional electronic microscopy: measuring the roughness of the surface and looking at it through full‐field optical microscopy. In addition, the electric resistivity is determined for the test specimens. It presents an increment from the blank value of 6.5 × 10−8 Ωm (free of fatigue damage) to 1.25 × 10−7 Ωm for the fatigue test specimen (εa = 0.6%). Finally, X‐ray diffraction patterns are determined for analyzing the residual equivalent strain at the microscale for the fatigued samples. The residual equivalent strain exhibits a trend toward increasing. For instance, it increases from 18.5 (blank value) to 34.0 με for the fatigue test specimen with εa = 0.6%. [ABSTRACT FROM AUTHOR]

The crystal structures of type 1234 and 2234 are not found in compositions Bi1-xBxSr2Ca3Cu4Oy and Bi2-xBxSr2Ca3Cu4Oy after synthesis under conditions of ambient pressure P = 1 bar and T = 835 °C for τ = 240 h. This conclusion is obtained as a result of the fact that the series of bismuth superconductors Bi1-xBxSr2Ca3Cu4Oy, Bi2-xBxSr2Ca3Cu4Oy, Bi2-xBxSr2Ca2Cu3Oy, Bi1.7-xBxPb0.3Sr2Ca2Cu3Oy with different boron content x = 0-2 were synthesized followed by slow (rate < 10 °C/sec) cooling or quenching (< 100 °C/sec). Samples of Bi1.7-xBxPb0.3Sr2Ca2Cu3Oy with a boron content of x = 0.5 have a significant (> 35%) proportion of the superconducting phase 2223, regardless of the accuracy of observing the temperature modes of synthesis (in temperature ranges < ±10 °C) and cooling after it. A model of the effect of boron on phase equilibrium in Bi-Pb-Sr-Ca-Cu-O system is proposed using the process of boron-bismuth glass formation. Therefore, the boron addition during the synthesis of bismuth superconductors will increase the production process reproducibility of phase 2223. Also, this technology can be used at the synthesis of superconductors from the boron-bismuth not very enriched ores in conditions of limited available resources. [ABSTRACT FROM AUTHOR]

The magnetization value and electric resistivity of the single-crystalline sample of Ni50Fe19Co4Ga27 shape memory alloy were measured. The elastic modulus was determined by the Dynamic Mechanical Analysis (DMA). The characteristic temperatures of martensitic transformation (MT) of the alloy were estimated from the temperature dependences of magnetization, electric resistivity and elastic modulus. A significant disparity between MT temperatures resulting from DMA and those estimated from magnetic and resistivity measurements was discovered. It was argued that the discrepancy is caused by the non-uniform mechanical stressing of twinned single crystal by the DMA analyzer. Moreover, the DMA measurements revealed a significant decrease of the elastic modulus of twinned martensite under the applied magnetic field of 1.5 kOe. To explain this effect, the temperature-dependent Young’s modulus of twinned crystal lattice was computed. The computations showed that the experimentally observed field-induced change of the elastic modulus is caused by the stress-assisted detwinning of the crystal lattice by the applied magnetic field. [ABSTRACT FROM AUTHOR]

Electrical resistivity (ER) method, non-destructive approach determining subsurface anomalies by leveraging electrical properties. In-situ ER is popular owing to its quick, reliable and continuous subsurface data, although heterogeneity across horizontal and vertical orientation is less explored. In this regard, present study tends to understand this effect by carrying out small-scale laboratory ER tests focusing on how varying vertical soil layer positions impact resistivity. Two distinct soil types with varying resistivity were arranged in both perpendicular and parallel direction to current flow, where low and high resistive layers were placed adjacent to one another. Results derived from study indicated that placement of low resistive soil before high resistive one leads to 37.58 % reduction in resistivity. Furthermore, parallel alignment resulted in 9.89 % decrease compared to perpendicular layering. Thus, these findings tends to highlight significance of layering in influencing resistivity values and underscoring the complexity of electrical resistivity testing. [ABSTRACT FROM AUTHOR]

The effects of water absorption on the electric resistivity and dielectric constant of polyimide (PI) and poly(ethylene terephthalate) (PET) were investigated, and the mechanism of deterioration in electrical insulation properties was discussed. The polyimides are poly(oxydianiline pyromellitimide) (PMDA–ODA) and poly(para-phenylene diamine biphenyltetracarboxydiimide) (BPDA–PDA). These polymer films were immersed in pure water for various immersion times at room temperature, and the water absorption ratio was evaluated. The electric resistance for these films was measured at room temperature using a high-resistance meter, and the dielectric constant at room temperature was measured using an LCR meter in a frequency range of 200 kHz to 2 MHz. The absorption ratios at equilibrium absorption for PMDA–ODA, BPDA–PDA, and PET were 2.7, 2.5, and 0.5%, respectively. The critical volume fraction of the percolation threshold of electric conductivity due to water absorption was 0.034 for both PMDA–ODA and BPDA–PDA. On the other hand, PET did not show a significant decrease in the resistivity. For both PIs and PET, the dielectric constant observed could be explained by a series model of the respective capacitances of pure water and polymer. Actually, the resistivity of samples cut from the edges of the film after water absorption was almost the same value as that in the dry state. These results suggest that the absorbed water molecules are not uniformly dispersed in the film but are localized at the edges of the film even after the absorption equilibrium has been reached. [ABSTRACT FROM AUTHOR]

In our present work, we report the synthesis of Sb-doped SnO2-coated TiO2 (TiO2@Sb-SnO2) conductive nanocomposites by hydrothermal method. Firstly, titanate whiskers were hydrothermally synthesized at 175 °C using sodium hydroxide and metatitanic acid as starting materials with a molar ratio of 4:1. And then, the TiO2@Sb-SnO2 nanocomposites were hydrothermally synthesized with the use of the as-synthesized titanate whiskers, tin tetrachloride, and antimony trichloride as starting materials at 185 °C. In the hydrothermal reaction process, Sb-doped SnO2 nanoparticles enhanced the phase transition from titanate to rutile TiO2. The oxidation states of tin and antimony elements are Sn4+, Sb5+, and Sb3+, respectively. TEM and HRTEM analyses indicated that the Sb-doped SnO2 nanoparticles with an average particle size of around 1.5 nm were coated on the surfaces of TiO2 nanoparticulates with an average particle size of around 20 nm. The TiO2@(1%)Sb-(10%)SnO2 nanocomposites had a minimum electric resistivity of 5.97 × 103 Ω·cm. Filling of the TiO2@Sb-SnO2 nanocomposites increased the electric conductivity of waterborne polyester films, endowing the polyester films with static electron dissipativity. [ABSTRACT FROM AUTHOR]

The present work has examined the thermal features of glassy chacogenide materials Se0.75-xTe0.25Agx (x = 0, 2, 4, 6, 8, 10 at %). The thermal stability of these compositions has been assessed under non-isothermal conditions using Differential Scanning Calorimetry (DSC), which has been used to find the glass transition temperature (Tg), the initial crystallization temperature (Tin), the temperature corresponding to the top of the crystallization rate (Tp), and the melting temperature (Tm). In addition, the kinetic parameter Kr(T) was given as an additional sign of thermal stability. Among these compositions, it was discovered that Se0.71Te0.25Ag0.04 had the best glass-forming ability and glass-thermal stability. The average coordination numbers of the considered samples have been discussed in relation to these results. Additionally, we measured the sheet resistivity, ρ, whose thickness is equivalent to 1000 nm at heating rate 5 K/min, in this work to study the crystallization kinetics of thick films of Se0.75-xTe0.25Agx (x = 0, 2, 4, 6, 8, 10 at %) in the temperature range of 300 to 625 K. This range was sufficient to draw attention to two substantial areas in the resistivity versus temperature curve, and the derivation of resistivity as a function of temperature established that the films under study only had one crystallization region. [ABSTRACT FROM AUTHOR]

Dalle de verre windows consist of thick slabs of coloured glass set in a matrix of reinforced concrete. The invention of this special art form is closely linked to the developments in modern architecture in the first half of the 20th century that are characterized by using new technologies such as steel-frame construction, reinforced concrete and the increasing use of glass. Many of these windows are showing damage, some of it severe. Until now, the causes of damage have hardly been investigated and there is still no practical and suitable approach to the analysis of the state of conservation of dalle de verre glazings. One of the main objectives of an interdisciplinary project (2019–2021) was therefore to evaluate the potential of non-destructive techniques for the characterisation of and identification of damage of dalle the verre windows in their structural, physical and climatic context. Various non-destructive methods (Ground-Penetrating Radar, Electric resistivity, Half-cell potential, Ultrasonics, Induction, Magnet and Thermography) have been tested on two prominent dalle de verre examples: the windows created by Fernand Léger for the church of Saint-Germain d’Auxerre in Courfaivre (Swiss Jura mountains) and the large tripartite by Alexandre Cingria once decorating the choir window church of the Franciscan monastery at Fribourg, Switzerland. The results of the analyses presented in this paper provide valuable information on the advantages and limitations as well as the costs of the methods used.

Este trabajo presenta la caracterización geológica-geofísica de una probable ocurrencia de oro en Santa Catarina Gabro, en la región de São Sepé, estado de Rio Grande do Sul, sur de Brasil. Trabajos anteriores han indicado la presencia de oro en la región en las actuales campañas de prospección geoquímica de sedimentos y sugieren que el área de origen sería Santa Catarina Gabro. Para investigar sobre esta probable ocurrencia de oro, se realizaron estudios geológicos y estructurales, seguidos de la adquisición de información geofísica utilizando los métodos de resistividad DC e IP, con el arreglo dipolo-dipolo. Los datos geofísicos fueron procesados en inversión 2D y luego interpolados para permitir la visualización tridimensional de la posible mineralización. Interpretaciones basadas en la recopilación de datos geológicos y geofísicos, en asociación con el contexto estructural regional, sugieren que la probable mineralización se originó a partir de la intrusión del Granito São Sepé, cuyos fluidos hidrotermales se alojaron en fracturas durante los eventos tectónicos ocurridos en la región. Los resultados obtenidos en este trabajo permiten delinear una arquitectura de yacimiento factible con el contexto geológico de la región y ayudar a una futura estrategia de perforación dirigida a los objetivos probables identificados.

Dalle de verre windows consist of thick slabs of coloured glass set in a matrix of reinforced concrete. The invention of this special art form is closely linked to the developments in modern architecture in the first half of the 20th century that are characterized by using new technologies such as steel-frame construction, reinforced concrete and the increasing use of glass. Many of these windows are showing damage, some of it severe. Until now, the causes of damage have hardly been investigated and there is still no practical and suitable approach to the analysis of the state of conservation of dalle de verre glazings. One of the main objectives of an interdisciplinary project (2019–2021) was therefore to evaluate the potential of non-destructive techniques for the characterisation of and identification of damage of dalle the verre windows in their structural, physical and climatic context. Various non-destructive methods (Ground-Penetrating Radar, Electric resistivity, Half-cell potential, Ultrasonics, Induction, Magnet and Thermography) have been tested on two prominent dalle de verre examples: the windows created by Fernand Léger for the church of Saint-Germain d'Auxerre in Courfaivre (Swiss Jura mountains) and the large tripartite by Alexandre Cingria once decorating the choir window church of the Franciscan monastery at Fribourg, Switzerland. The results of the analyses presented in this paper provide valuable information on the advantages and limitations as well as the costs of the methods used. [ABSTRACT FROM AUTHOR]

The effects of water absorption on the electric resistivity and dielectric constant of polyimide (PI) and poly(ethylene terephthalate) (PET) were investigated, and the mechanism of deterioration in electrical insulation properties was discussed. The polyimides are poly(oxydianiline pyromellitimide) (PMDA–ODA) and poly(para-phenylene diamine biphenyltetracarboxydiimide) (BPDA–PDA). These polymer films were immersed in pure water for various immersion times at room temperature, and the water absorption ratio was evaluated. The electric resistance for these films was measured at room temperature using a high-resistance meter, and the dielectric constant at room temperature was measured using an LCR meter in a frequency range of 200 kHz to 2 MHz. The absorption ratios at equilibrium absorption for PMDA–ODA, BPDA–PDA, and PET were 2.7, 2.5, and 0.5%, respectively. The critical volume fraction of the percolation threshold of electric conductivity due to water absorption was 0.034 for both PMDA–ODA and BPDA–PDA. On the other hand, PET did not show a significant decrease in the resistivity. For both PIs and PET, the dielectric constant observed could be explained by a series model of the respective capacitances of pure water and polymer. Actually, the resistivity of samples cut from the edges of the film after water absorption was almost the same value as that in the dry state. These results suggest that the absorbed water molecules are not uniformly dispersed in the film but are localized at the edges of the film even after the absorption equilibrium has been reached.

Biochar and biochar-based composites are multi-functional materials with a wide range of environmental and other applications. A new and emerging application is in the field of modern communication systems as materials with significant electromagnetic shielding effectiveness. In this study, biochar was prepared from olive tree prunings which was subsequently used at various dosages to prepare composite samples with carbon black and polytetrafluoroethylene as binder. The electromagnetic shielding effectiveness of the samples were measured in the frequency range of 1–3 GHz, using a simple, user-friendly and reliable experimental set-up. The results showed that raw, unmodified biochar had a low shielding effectiveness in the range of 1.5-4 dB however, it slightly increased as the thickness of the sample increased from 0.1 to 0.5 mm. Modifying biochar with the 20 %w/w acetylene black largely increased its shielding effectiveness, reaching the value of 39 dB in the same frequency range. Our approach demonstrated that raw biochar can be used as a substrate to develop composite materials with significant shielding effectiveness and assess their performance with a quick and simple laboratory method.

The inclusion of carbon nanotubes (CNTs) in cementitious composites has been studied due to their electrical, thermal, and mechanical enhancing properties. Considering the hydrophobic characteristics of CNTs, these nanomaterials need to be well dispersed in the aqueous media in which they are inserted to guarantee those gains. Among the methods applied to produce such composites is the dispersion of CNTs on the surface of anhydrous cement particles using non-aqueous suspensions such as acetone, ethanol, or isopropanol. Even though those non-aqueous media have been individually studied by researchers, comparisons of the efficiency of CNTs dispersion was not found in the literature. Therefore, as a novelty, the present article aims to analyze the influence of the addition of the multi-walled CNTs dispersed in the cited three types of non-aqueous suspensions on the cement paste's electrical and mechanical properties. Pastes containing 0%, 0.5%, and 1.0% of CNTs were prepared on the surface of anhydrous cement particles using a pre-dispersion technique based on simultaneous sonication and mechanical agitation in the three cited media. Tests to determine electric-volumetric resistivity, compressive strength, and splitting tensile strength were performed. It was observed that acetone dispersion decreases the cement paste's electrical resistivity, even without the addition of CNTs. The cementitious composites with CNTs demonstrated increased mechanical strength (both compressive and tensile) using all three dispersion media. Statistical analysis (analysis of variance—ANOVA—and Tukey's Test) was performed to evaluate the significance of the results. [ABSTRACT FROM AUTHOR]

A mathematical model is presented to simulate the electric resistivity of leather samples as a function of humidity. It will be shown that absolute and not relative humidity is the crucial parameter. The model assumes that the leather includes channels that can absorb water from the surrounding environment. This effect primarily determines the electric conductivity of the leather samples. The theoretical results from the model are quite closely in line with experimental measurements.

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The inclusion of carbon nanotubes (CNTs) in cementitious composites has been studied due to their electrical, thermal, and mechanical enhancing properties. Considering the hydrophobic characteristics of CNTs, these nanomaterials need to be well dispersed in the aqueous media in which they are inserted to guarantee those gains. Among the methods applied to produce such composites is the dispersion of CNTs on the surface of anhydrous cement particles using non-aqueous suspensions such as acetone, ethanol, or isopropanol. Even though those non-aqueous media have been individually studied by researchers, comparisons of the efficiency of CNTs dispersion was not found in the literature. Therefore, as a novelty, the present article aims to analyze the influence of the addition of the multi-walled CNTs dispersed in the cited three types of non-aqueous suspensions on the cement paste’s electrical and mechanical properties. Pastes containing 0%, 0.5%, and 1.0% of CNTs were prepared on the surface of anhydrous cement particles using a pre-dispersion technique based on simultaneous sonication and mechanical agitation in the three cited media. Tests to determine electric-volumetric resistivity, compressive strength, and splitting tensile strength were performed. It was observed that acetone dispersion decreases the cement paste’s electrical resistivity, even without the addition of CNTs. The cementitious composites with CNTs demonstrated increased mechanical strength (both compressive and tensile) using all three dispersion media. Statistical analysis (analysis of variance—ANOVA—and Tukey’s Test) was performed to evaluate the significance of the results.

This paper focuses on changes in potential drops over different parts of a two-compartment electrodialtyic cell during a process developed for P recovery from sewage sludge ash and simultaneous removal of heavy metals. The cell has two compartments separated by a cation exchange membrane. The ash suspension is in the anode compartment. The major aim of this work is to obtain knowledge needed to optimize the energy consumption for the process. Initially, a low conductivity of the suspension caused a relatively high resistance in the suspension itself. The adjacent catholyte contrast with a high conductivity and a low pH. A high membrane resistivity was seen because of the concentration and pH gradients. During the treatment, the gradients leveled out and, the overall voltage reached a low level. However, at this point, where the suspension is acidic, protons are major current carriers, which is a waste of energy to the overall recovery process, since current should be spent to transport metal cations across the membrane. Thus, the investigation points at two major issues for future optimization; the gradients over the cation exchange membrane (pH, conductivity, potential) and improved utilization of the produced protons to be for P extraction rather than carrying current.

The resistivity method in geophysics is used to solve various geological and engineering problems. Recently, this nondestructive method has been used on trees to investigate possible infections within the trunks by scanning resistivity variations. In this study, the electrical resistivity method has been aimed to be applied on various trees in Istanbul, Turkey to test whether the method applies to trees via regular resistivity measurement devices used in geophysics. Firstly, a multi-channel resistivity device, that is designed to automatically take measurements on the ground, is modified to carry out the measurements on trees. The measured data are processed using two different approaches. The first approach is to prepare a program in MATLAB, which is capable of adapting measurement points into a circular profile via interpolation. The data processed with this program are then gridded to prepare resistivity contour slices. The detection and handling of faulty measurements are discussed briefly in this section. The second approach is to use an open-source electrical tomography program (BERT V2) to apply inversion to the collected resistivity data. Finally, all the results and conclusions are interpreted considering the resistivity distribution within tree trunks, including sample slices from two trees that are known to have defected beforehand. As a conclusion of our studies, we have found that a regular resistivity measurement device used in earth sciences is applicable to an extent on trees to investigate possible defects within their trunks. [ABSTRACT FROM AUTHOR]

The superconducting properties of the RuSr2GdCu2O8 ceramic system depend strongly on the synthesis conditions and the ionic substitutions. In this work, we studied the structural and electrical properties of the Ru0.9M0.1Sr2GdCu2O8 system, with M = Zr, Mo, and Mn. The samples were prepared by solid-state reaction at ambient pressure in air, using temperatures between 980 °C and 1020 °C. X-ray powder diffraction patterns indicate that all samples crystallize in a tetragonal symmetry (S.G. P4/mmm, No. 123). The structural data of each sample was refined by the Rietveld method, showing that the Cu-O (1) and Ru-O (1) bond lengths vary with the substituted ionic radii of Zr, Mo, and Mn ions. Electrical resistance measurements indicate that the samples annealed in flowing oxygen at 1050 °C and 1055 °C for 5 days exhibit a semiconductor like behavior for M = Mo and Mn, whereas the samples with M = Zr and Ru show superconducting behavior.

The degradation of MSW in landfills occurs naturally from the beginning of the disposal, during landfill operation and even after its closure, over a period of several years. The monitoring of closed landfills can be quite costly when done only by direct methods, especially in areas where technical and financial resources are restricted. This work presents a case study in the extreme south of Brazil that represents the vast majority of landfills in the country: public landfills, in small ditches with little resources. The geophysical survey sought to identify leachate accumulation zones and verify their chemical stability in relation to the geological environment from the joint analysis of the electrical resistivity and self-potential data. Data acquisition took place on the same date (02/2018), with results that reveal leachate generation areas (−60 mV and ~ 30 Ωm), leachate accumulation (−40 mV and ~ 20 Ωm) and areas with a predominance of inert waste (> 40 mV), where previously existing organic matter was practically degraded. The combined use of geoelectric methods to understand the degradation dynamics of organic matter in landfills allows for the recognition of active zones of leachate generation, information that supports chemical stabilization projects and site remediation. [ABSTRACT FROM AUTHOR]

We study the influence of temperature, stresses, and resistivity of a foam masses on the intensity of moisture removal. We select three zones of changes in the electric resistivity. The distribution of the pressure field is connected with the filtration of moisture in capillary-porous materials. For the insufficient structural strength of interporous partitions and sharp changes in temperature, we observe the phenomenon of subsidence of the foam masses. We analyze the character of changes in membranes for the maximum possible increase in the volume of the pore and evaluate the volume of refractory component, which forms the shells of pores (cells). The filtration of liquid in the analyzed foam mass under the action of pressure gradient is characterized by its viscosity and the geometric parameters of the capillary-porous body. In the case of self-compaction of the foam system, the process of mass transfer becomes more complicated due to the changes in the filtration characteristics of the matrix. In order to exclude the stressed state in the adobe body after electric heating, the body should be gradually cooled down to a temperature safe for its structure. [ABSTRACT FROM AUTHOR]

Positron annihilation lifetime spectroscopy at room temperature is used to investigate polycrystalline Cu-Zn ferrite samples substituted with Nd. Standard ceramic technique is used to prepare all investigated samples. The variation of positron annihilation parameters I1%, I2%, τ1, and τ2 are demonstrated with grain size, initial permeability, homogeneity of the samples, and electrical resistivity with Nd concentration. The important novel points are: (1) Intragranular pores are equal to the sum of intra- and interdomain pores. The lifetime τ1 is increased due to the decrease of the intradomain pores. The initial permeability and homogeneity are decreased with increasing the interdomain pores. The electrical resistivity is increased due to the increase of the interdomain pores. [ABSTRACT FROM AUTHOR]

The potentialities of studying rock wettability by X-ray core tomography are considered using Visean terrigenous reservoirs of the Solikamsk depression as an example. The studies included comparison of the tomograms of core samples in a dry state and saturated of sodium iodide solution, which acts as a radiopaque analog of formation water. Differences in impregnation of the core samples, characterizing their wettability, have been established. According to the tomography data, in the hydrophilic samples the solution filled all pores, except for a small portion of the largest ones. In the hydrophobic samples, there was no impregnation of both small and large pores in the central zone. Based on the tomograms, the rocks were divided into groups by their wettability: absolutely hydrophobic, with strong signs of hydrophobicity, with signs of hydrophobicity, and hydrophilic. Comparison of the results of tomography with the standard approach showed that the Tulbovich method commonly used for the study area does not fully reflect the rock wettability. Comparison of the results of core tomography and study of thin sections with the results of electrometric logging shows their good agreement. The rocks with absolute hydrophobicity established by tomography have an anomalously high electric resistivity, >1000 Ohm·m, and the rocks with signs of hydrophobicity, >120 Ohm·m. For the hydrophilic intervals, the electric resistivity values are significantly lower, from 17 to 100 Ohm·m. Thin sections of the core samples were studied. Their microscopic analysis has shown a higher content of organic matter in the hydrophobic rocks as compared with the hydrophilic ones. Few exceptions might be due to the study of only local thin sections of the samples. Thus, rock wettability can be monitored by electrical methods, especially lateral logging. The results of the assessment of rock wettability by core study and well logging can be compiled for the exploration of Visean deposits of the Solikamsk depression. Geological models constructed with regard to the recognized zones of hydrophilic and hydrophobic reservoirs can be effectively used to optimize exploration of deposits, especially reservoir flooding. [ABSTRACT FROM AUTHOR]

The results of measurements of the electrical properties of rocks and induced polarization surveying are analyzed for three gold-ore deposits including the Bamskoe, Berezitovoe, and Pokrovka in the Upper Priamurye region. The spatial correlation is shown between mineralization zones and contrasting resistivity boundaries mapped within the gold-ore fields. The assumption is validated that the blocks of high-resistivity rocks have minimal permeability and therefore they were able to act as screens affecting the hydrodynamic features of the hydrothermal system at the stages of deposit formation and at the stages of mineralization formation. This makes such geoelectrical boundaries an important element for exploration, which should be accounted for when interpreting electric prospecting data. The induced polarization survey establishes a diverse interpretation of the polarizability anomalies within the gold-ore fields and a lack of correlation between ranges of increased induced polarization values and gold-ore mineralization. Methods for evaluating polarizability anomalies are proposed. [ABSTRACT FROM AUTHOR]

Twist channel angular pressing (TCAP), the severe plastic deformation (SPD) technology developed recently to increase the efficiency of the imposed strain and its homogeneity within a single pass, is an effective process combining channel bending and twist extrusion in a single die. The presented study analyses the phenomena of substructure development, precipitation, structural units' orientations, and the occurrence of residual stress, as well as electric resistivity and microhardness, in commercial purity aluminium naturally aged for two years at room temperature after processing via single pass TCAP. The results are compared with the findings for the TCAP sample right after processing; selected results are also compared with the results for the sample after TCAP and one year of natural ageing, and with a sample processed by conventional ECAP. The analyses showed the substructure to recover substantially, the grain size decreased to submicron size. The residual stress within the grains introduced by the energy accumulated via the severe imposed strain relaxed significantly by the structure restoration, as well as by intensive precipitation. The aged TCAP sample specific electric resistivity was comparable to the resistivity of the original commercially pure aluminium (2.652E-05 and 2.635E-05 Ω·mm2·m−1, respectively), however, the microhardness mapping showed increased mechanical properties with homogeneous distribution. • Investigation of sub-structure development after twist channel angular pressing and ageing • Natural ageing increased electric conductivity and mechanical properties. • Ultra-fine grains with high angle boundaries were formed. • Natural ageing led to reduction of residual stress. [ABSTRACT FROM AUTHOR]

During the processes of methane adsorption and desorption, the internal structure of coal changes, accordingly leading to changes in electrical conductivity. In this paper, using low rank coal seams of the Yan'an Formation in the Dafosi field as the research subject, the relationship between coal resistivity, methane adsorption quantity, and equilibrium pressure is analyzed through proximate analysis, mercury injection tests, low temperature liquid nitrogen adsorption tests, and coal resistivity measurements during methane adsorption and desorption. The results show that during the process of pressure rise and methane adsorption, the conductivity of coal increases, resulting from heat release from methane adsorption, coal matrix swelling and adsorbed water molecules replaced by methane, but the resistivity reduction gradually decreases. The relationship between coal resistivity and methane adsorption quantity and equilibrium pressure can be described by a quadratic function. During the processes of depressurization and desorption, the resistivity of coal rebounds slightly, due to decalescence of methane desorption, coal matrix shrinkage and water‐gas displacement, and the relationship coincides with a linear function. Methane adsorption leads to irreversible changes in coal internal structure and enhances the coal conductivity, and resistivity cannot be restored to the initial level even after methane desorption. The resistivity and reduction rate of durain are higher than those of vitrain, with relatively greater homogeneous pore throat structure and fewer charged particles in the double electric layer. In addition, moisture can enhance the conductivity of coal and makes it change more complexly during methane adsorption and desorption. [ABSTRACT FROM AUTHOR]

Abstract Amorphous ribbons of Al 86 Ni 4 Co 4 Gd 6 , Al 86 Ni 4 Co 4 Tb 6 and Al 86 Ni 6 Co 2 Tb 6 compositions were produced by a standard planar flow casting method. Their kinetics of crystallization was studied by X-rays, DSC and electric resistivity. Al – (Ni + Co) – REM metallic glasses are characterized by the wider (for 100 K) interval of amorphous state in comparison with Al-Ni-REM and Al-Co-REM alloys. They have higher values of electric resistivity and their crystallization goes in more complicated way. The alloy with Gd demonstrates wider and more stable interval of amorphous state in comparison with Tb-containing alloys, and the combination (4% Ni + 4% Co) is preferable than (6% Ni + 2% Co). Highlights • Amorphous ribbons were produced by a standard planar flow method. • Four stages of crystallization were found in Al-Ni-Co-Gd(Tb) amorphous alloys. • Al-Ni-Co-R alloys are characterized by the wider interval of amorphous state. [ABSTRACT FROM AUTHOR]

The superconducting properties of the RuSr2GdCu2O8 ceramic system depend strongly on the synthesis conditions and the ionic substitutions. In this work, we studied the structural and electrical properties of the Ru0.9M0.1Sr2GdCu2O8 system, with M = Zr, Mo, and Mn. The samples were prepared by solid-state reaction at ambient pressure in air, using temperatures between 980 °C and 1020 °C. X-ray powder diffraction patterns indicate that all samples crystallize in a tetragonal symmetry (S.G. P4/mmm, No. 123). The structural data of each sample was refined by the Rietveld method, showing that the Cu-O (1) and Ru-O (1) bond lengths vary with the substituted ionic radii of Zr, Mo, and Mn ions. Electrical resistance measurements indicate that the samples annealed in flowing oxygen at 1050 °C and 1055 °C for 5 days exhibit a semiconductor like behavior for M = Mo and Mn, whereas the samples with M = Zr and Ru show superconducting behavior. [ABSTRACT FROM AUTHOR]

The Ellenburger–San Saba aquifer discharges spring flows into the overlying Hamilton Creek bed in Burnet County, central Texas. The aquifer is susceptible to contamination from surface‐water reservoirs because of the presence of dissolution cavities that are hydraulically connected to the reservoirs in some locations. There is concern that preferential groundwater seepage from reservoirs into the aquifer in these locations might ultimately degrade the quality of the springwater that enters Hamilton Creek. To investigate preferential groundwater seepage patterns and hydraulic connectivity between surface‐water reservoirs and the Ellenburger–San Saba aquifer, geophysical reconnaissance surveys were completed between July 2017 and January 2018 to map dissolution cavities and locate preferential groundwater seepage within a specific region of the aquifer. Two‐dimensional electric resistivity tomography and self‐potential profiling were utilized, and a simplified, three‐dimensional finite‐element model of the field site was constructed to provide an interpretive aid. The self‐potential data indicated the occurrence of preferential groundwater seepage through a porous seepage conduit that was imaged by the electric resistivity tomography data but did not indicate the occurrence of groundwater seepage through two fluid‐filled dissolution cavities that were imaged by electric resistivity tomography data. Collectively, the surveying and modelling results demonstrate the efficacy of geoelectric methods for mapping the locations of dissolution cavities and preferential groundwater seepage in the electrically resistive karst terrane of the Ellenburger–San Saba aquifer. [ABSTRACT FROM AUTHOR]

The electric and thermal transport properties (electric resistivity ρ, magneto-resistance MR , Hall coefficient R H and anomalous Hall effect, thermal conductivity Κ and Seebeck coefficient S ) of the off-stoichiometric Ni 1.92 Mn 1.56 Sn 0.52 Heusler alloy were measured in a wide temperature and magnetic field range. The simultaneous measurement of several transport and magnetic properties offers a possibility to combine information arising from the received experimental results. The phonon and the charge carriers parts of complex temperature dependence of thermal conductivity K(T) were consistently separated using the Lorentz factor and temperature dependence of resistivity ρ (T) . The positive values of the Hall coefficient R H has been determined in martensite phase of the alloy at low temperatures. R H reaches zero value at temperature range where the so-called “paramagnetic gap” was observed and the negative value of R H was detected in austenite phase. Temperature dependence of the Hall coefficient R H (T) was used to derive both, the density and the mobility of charge carriers. The standard relations were used to describe the measured temperature dependence of the Seebeck coefficient. All the received result point to an important role of changes in electronic structure of the alloy in all the studied transport effects. A scenario of the complex behavior of the transport properties of the Heusler alloy based on a possible existence of an energy gap in electronic structure is discussed. [ABSTRACT FROM AUTHOR]

In cold regions, concrete structures suffer from low temperatures, where damage will initiate due to the expansion of ice formation and accumulate with water supply to keep penetrating into the pores and cracks. Meanwhile, it is found that the mechanical properties of cementitious materials can be enhanced owing to the pores filled by ice. Therefore, it is important to evaluate the freezing process, in which the freezing action can have both strengthening and damaging effects on the mechanical properties of concrete material, depending on several environmental and material factors. Besides, if temperature remains negative, the capacity of cementitious materials in service with ice presented inside pores and cracks are also important. However, there is still lack of effective evaluation methods for the mechanical properties of frozen concrete. In this study, cementitious materials with/without air entraining agent (AEA) of different water-to-cement ratios (W/C) are prepared and tested at low temperatures (−10, −20, −30 and −40 °C). The results show that the mechanical properties of the materials (compressive strength, splitting tensile strength, dynamic elastic modulus) are closely related to electrical resistivity, which is further explained by the impact of air voids and pore structures from a multiscale scheme. It proves that the change of resistivity could be adopted as the index to evaluate the performance of frozen concrete, and an empirical model is derived based on the experiment results. [ABSTRACT FROM AUTHOR]

The most important estimation parameter – the open porosity coefficient (Kp) - in petrophysical laboratories is, as a rule, determined for the productive formation on the whole and without taking into account its regional heterogeneity. As a basic criterion at selecting the samples to construct the model Rp = f(Kp) a range of the porosity value is taken. In this case it is assumed that the higher is Δ Kp , the higher is the validity of the relation Rp = f(Kp). However, in practice such concept often creates the problems of ambiguity in determining the porosity by the electric resistivity of water saturated samples in different wells even within one field. This phenomenon is resulted from neglecting, on one hand, the specific features of the regional petrophysics object - facies, which are reflected in the form of well logging curves including SP, and, on the other hand, the element of the general petrophysics object – a type of clayness. The breakdown (classification) of the formation by facies, determination and taking into consideration the type of clayness as well as distinguishing and analysis of petrophysical types of rock based on the rock porosity and permeability characteristics within a formation permit to obtain satisfactory relations between electric resistivity and porosity of the rock.

The deepness of soil-permafrost layer was measured bу vertical electrical resistivity sounding. It has been revealed that the deepness of active layer оn the Point Thomas oasis , King George lsland is in average about 100-150 cm, while оn the Argentine lslands it is 40-50 cm, which is caused bу climatic conditions. Weak soils of the Argentine Islands are connected to permafrost via the massive rock, while in case of Point Thomas oasis (King-George Island) fine-coarsy gravel soils are underlayed directly bу permafrost.

Positron annihilation lifetime spectroscopy (PALS) is used to investigate polycrystalline substituted Li-ferrite samples. The dray ceramic technique was used to prepare all investigated samples. The variation of positron annihilation parameters I1%, I2%, τ1, and τ2 has been demonstrated with porosity and the initial permeability against the ionic radii of substituted ions for Li ferrite. The grain size (G.S.) increased with increasing the ionic radii of the substituted ions for Li-ferrite. The correlation between I2 and τ2 has opposite behavior with the ionic radii of the substituted ions. Whereas the correlation between I1 and τ1; has nearly the same behavior with the ionic radii of the substituted ions except for V and Gd samples. There is mostly a direct correlation between the electrical resistivity and I2 values except for Sm sample with increasing the ionic radii of substituted ions.

The piezoresistivity of cement-based material has already been investigated, but mainly restricted to compressive stress sensing due to brittleness of concrete. Conversely, Engineered Cementitious Composites (ECC) presents superb tensile ductility and pseudo strain-hardening property, which offers unique opportunity for exploring sensing of tensile stress/strain. In this paper, Carbon Black (CB) and supplementary cementitious materials (SCM) were incorporated into ECC to decrease the bulk resistivity and simultaneously acquire high tensile ductility. The resistance of ECC, high fly ash (HFA)-ECC and CB-ECC was measured through a two-probe method under uniaxial tension test. All specimens exhibited increase of resistivity once cracks occurred between two electrodes. The fractional Gauge Factor (GF) in strain-hardening segment was calculated and the relationship of GF and tensile strain was experimentally investigated, which could be potentially utilized in the field of structural health monitoring to enhance the safety of concrete infrastructures. [ABSTRACT FROM AUTHOR]

Shape and position of modern polluted sediment bodies in the floodplain internal structure can provide insight into past and future erosional/deposition behaviour of fluvial systems. Extensive field works needed for such studies can be mitigated by the use of geophysical imaging, originally developed for engineering practice but still rather sparsely used in floodplain research. We demonstrate the performance of electrical resistivity tomography (ERT), dipole electromagnetic profiling (DEMP), and X-ray fluorescence spectroscopy for identification of subsurface sediment bodies of contrasting lithology, age, and pollution status; we found minor remnants of unpolluted (ancient) floodplain segments that would likely have been overlooked in arbitrary “blind” sampling. Pollution chemostratigraphy of floodplains based on the concentrations of certain risk elements can be affected by post-depositional migration. We thus identified signatures related to mining and smelting that are carried by coarser particles (gangue, fly ash) not expected to undergo post-depositional translocations in alluvium: the local enrichment factor of Zr (LEF Zr) and mass-specific magnetic susceptibility (χ). The LEF Zr differentiated pre-mining floodplain sediments which originated from erosion of Zr-rich catchment loess soils from Zr-poor, gangue-derived material. χ exhibits a step-like increase above the threshold value of approximately 25·10 −8  m 3 /kg in severely polluted sediments; we assign that χ step to the replacement of charcoal and wood by coke in smelting technology during the late 19th century. The shape of the unpolluted sedimentary bodies, as well as bodies of historically changing pollution extent, indicate considerable recent lateral river instability. A mild aggradation flattened the floodplain surface and prevented the identification of buried sedimentary bodies by surface topography, but did not restrict the power of the geophysical imaging. [ABSTRACT FROM AUTHOR]

This paper introduces black photoresist specially designed for making black layers on flexible film. Flexibility, broad tapered profile, high optical density (OD) and high electric resistance are achieved. The flexibility is suitable for film type devices and the high electric resistivity is likely suitable for black matrix (BM) and micro light emitted diode (LED). [ABSTRACT FROM AUTHOR]

CuMg (CM) and ITO/CuMg (ICM) films with Mg contents ranging from 30 to 65 at% are deposited on glass substrates and are then treated by furnace annealing and laser annealing. The structural, optical and electrical properties of the as-deposited and annealed samples are investigated and compared. It is shown that as the Mg content increases, the sheet resistance of the CM film increases, while the transmittance decreases. For a Mg content of 49 at%, the bi-layer ITO/CM structure improves the transmittance from 62.6% (CM) to 75.6% (ICM) and reduces the resistance from 51.3 Ω/□ (CM) to 49.5 Ω/□ (ICM). Moreover, following furnace annealing at 200 °C, the transmittance of the ICM sample is further improved to 78.5% while the sheet resistance is reduced to 32.4 Ω/□. The corresponding figure of merit is equal to 2.74 × 10 −3 Ω −1 , and is thus similar to that of commercial ITO film (2.68 × 10 −3 Ω −1 ). The optimal laser annealing parameters for the Cu 51 Mg 49 ICM sample are found to be a pulse energy of 1 μJ and a repetition rate of 250 kHz. Given the use of these parameters, the ICM film has a transmittance of 77.5% and a sheet resistance of 26.5 Ω/□. The corresponding figure of merit has a value of 2.94 × 10 −3 Ω −1 . Finally, the relative change in resistivity of the as-deposited Cu 43 Mg 57 ICM sample following fatigue testing with a bend radius of 7 mm (ΔR/R 0 = 0.21) is significantly lower than that of a pure ITO film of roughly equivalent thickness (ΔR/R 0 = 0.93). [ABSTRACT FROM AUTHOR]

Monitoring power transformers oils conditions is a permanent concern for equipment users, to avoid their unplanned (accidental) removal from operation. This paper presents a new method for determining oil resistivity by measuring the absorption/resorption currents and calculating the parameters of the lifetime line, the consumed lifetime, and the lifetime reserve of the insulating oil, during transformer operation at constant and variable temperature. The resistivity values determined in the laboratory on an unaged PRISTA mineral oil with a new online measuring cell are analysed and compared to those obtained with a standard cell. Finally, it is shown that the results obtained with the new measuring cell support its mounting on a power transformer for real-time determination of oil parameters. [ABSTRACT FROM AUTHOR]