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Consistent c-axis orientation characteristics toward the direction of applied pressure of Y-type BaSrCo2Fe11AlO22 (BSCFAO-θ) were successfully prepared by the strategy of hot pressing. The samples' magnetoelectric coupling performance was greatly enhanced by the strategy of hot pressing than that of the traditional solid reaction method. The magnetoelectric current of BSCFAO-θ (θ = 0°) (12.06 μA/m2) was nearly 5 times higher than BSCFAO-SS (2.24 μA/m2). The magnetoelectric polarization of BSCFAO-θ (θ = 0°) (32.82 μC/m2) was nearly 4 times higher than that of BSCFAO-SS (8.31 μC/m2). The magnetoelectric coupling coefficients of BSCFAO-θ (θ = 0°) (1880 ps/m) were nearly 4 times higher than those of BSCFAO-SS (404 ps/m). The enhancement of magnetoelectric polarization of BSCFAO-θ (θ = 0°) can be attributed to the uniform c-axis orientation, which reinforced magnetoelectric polarization compared with none orientation that eliminated the magnetoelectric polarization on grain boundaries. The magnetoelectric coupling performance of BSCFAO-θ presented a gradually decreasing trend with the angle changing from 0° to 90° for the changing of orientation. Compared with traditional solid reaction methods, the strategy of hot pressing inhibits grain growth and increases grain boundaries, thus facilitating the enhancement of grain boundaries' resistivity, and the electrical resistivity of BSCFAO-θ (3.08 × 1010 Ω cm) was nearly 10 000 times higher than that of BSCFAO-SS (2.5 × 106 Ω cm), which also benefits the magnetoelectric polarization performance of BSCFAO-θ. Therefore, the hot-pressing strategy can contribute to the forming of oriented ceramics and enhance the grain boundaries' resistivity to improve magnetoelectric coupling performance. [ABSTRACT FROM AUTHOR]

Sputter deposition of ultrathick (≈ 20 μ m) Au–Ta alloy coatings on sphero-cylindrical substrates is key for the fabrication of hohlraums for magnetically assisted inertial confinement fusion. Here, we study the deposition of AuTa 4 alloy coatings onto rotating substrates. We use high-power impulse magnetron sputtering (HiPIMS) in a constant peak target voltage mode. Results show that the target erosion state has a strong impact on the dominant crystallographic phase, microstructure, surface morphology, and electrical resistivity of AuTa 4 films. This is due to effects of changes in the confining magnetic field with target erosion on the HiPIMS discharge characteristics and the sputter source output. We quantify these effects via plasma diagnostics and discuss the optimization of HiPIMS deposition of ultrathick films for cases when target erosion effects dominate film properties. [ABSTRACT FROM AUTHOR]

Reliable nanoswitch operation requires low contact voltages and stable electrical contact resistance (E C R). Surface cleanliness is crucial to prevent nanomechanical switch failure, which can occur due to the presence of insulating adventitious hydrocarbon films. In situ O2 plasma cleaning is effective but oxidizes metal surfaces. Here, the noble metal Pt, which forms PtOx, is employed to form electrodes. Previous studies report on PtOx electrical resistivity, but the effects of PtOx evolution at contacting interfaces due to electrical and mechanical stimuli have not been explored. This study investigates the impact of PtOx on E C R at low contact voltages under hot switching, cold switching, and mechanical cycling conditions. An increase in E C R upon plasma cleaning indicates the presence of a resistive PtOx layer. After hot and cold switch cycling at applied voltages of 300 mV or less, a low stable E C R is achieved. A higher contact voltage accelerates E C R stabilization. The results are consistent with PtOx film volatilization, which is primarily due to Joule heating rather than mechanical rupture. This investigation advances the understanding of interface evolution in plasma-cleaned nanoswitches. [ABSTRACT FROM AUTHOR]

Consistent c-axis orientation characteristics toward the direction of applied pressure of Y-type BaSrCo2Fe11AlO22 (BSCFAO-θ) were successfully prepared by the strategy of hot pressing. The samples' magnetoelectric coupling performance was greatly enhanced by the strategy of hot pressing than that of the traditional solid reaction method. The magnetoelectric current of BSCFAO-θ (θ = 0°) (12.06 μA/m2) was nearly 5 times higher than BSCFAO-SS (2.24 μA/m2). The magnetoelectric polarization of BSCFAO-θ (θ = 0°) (32.82 μC/m2) was nearly 4 times higher than that of BSCFAO-SS (8.31 μC/m2). The magnetoelectric coupling coefficients of BSCFAO-θ (θ = 0°) (1880 ps/m) were nearly 4 times higher than those of BSCFAO-SS (404 ps/m). The enhancement of magnetoelectric polarization of BSCFAO-θ (θ = 0°) can be attributed to the uniform c-axis orientation, which reinforced magnetoelectric polarization compared with none orientation that eliminated the magnetoelectric polarization on grain boundaries. The magnetoelectric coupling performance of BSCFAO-θ presented a gradually decreasing trend with the angle changing from 0° to 90° for the changing of orientation. Compared with traditional solid reaction methods, the strategy of hot pressing inhibits grain growth and increases grain boundaries, thus facilitating the enhancement of grain boundaries' resistivity, and the electrical resistivity of BSCFAO-θ (3.08 × 1010 Ω cm) was nearly 10 000 times higher than that of BSCFAO-SS (2.5 × 106 Ω cm), which also benefits the magnetoelectric polarization performance of BSCFAO-θ. Therefore, the hot-pressing strategy can contribute to the forming of oriented ceramics and enhance the grain boundaries' resistivity to improve magnetoelectric coupling performance. [ABSTRACT FROM AUTHOR]

κ-Ga2O3 has been predicted to be a potential ferroelectric material. In this work, undoped Ga2O3 films were grown by either plasma-enhanced atomic layer deposition (PEALD) or metal organic chemical vapor deposition (MOCVD) on platinized sapphire substrates. 50 nm thick PEALD films with a mixture of κ-Ga2O3 and β-Ga2O3 had a relative permittivity of ∼27, a loss tangent below 2%, and high electrical resistivity up to ∼1.5 MV/cm. 700 nm thick MOCVD films with predominantly the κ-Ga2O3 phase had relative permittivities of ∼18 and a loss tangent of 1% at 10 kHz. Neither film showed compelling evidence for ferroelectricity measured at fields up to 1.5 MV/cm, even after hundreds of cycles. Piezoresponse force microscopy measurements on bare κ-Ga2O3 showed a finite piezoelectric response that could not be reoriented for electric fields up to 1.33 MV/cm. [ABSTRACT FROM AUTHOR]

Vanadium dioxide (VO2) is a highly attractive and multifunctional material for technological applications due to its metal–insulator transition, which is accompanied by several orders of magnitude changes in electrical resistivity and optical transmissivity. In this work, we report on the metal–insulator transition of VO2 nanoparticles which are produced by a simple, efficient, and low-cost two-step preparation method based on infrared laser irradiation of V2O5 powder dispersed in water and subsequent stoichiometric stabilization by vacuum annealing at 773 K. VO2 nanoparticles have an average size of 36 nm with facet-like contours and undergo a structural phase transition from a monoclinic to a tetragonal phase, accompanied by a metal–insulator transition occurring around 323 K, which is about 17 K lower than bulk VO2. No evidence of the formation of intermediary metastable phases is observed. Our findings reveal that the size of VO2 nanoparticles is a key parameter to moving the transition closer to room temperature, which is important for many applications. [ABSTRACT FROM AUTHOR]

La0.7Sr0.3MnO3 (LSMO)-ZnO nanocomposites with varying concentrations of ZnO have been synthesized using the solution combustion method. A bimodal particle size distribution has been formed in all the samples. The crystallite size increases in the composites as compared to LSMO. The study on electrical resistivity reveals that LSMO exhibits a metal-to-insulator transition at 359 K, while the inclusion of ZnO suppresses the metallic behavior in the composites and increases the resistivity. Transport behavior of the samples in metallic and semiconducting regions has been explained with a known polynomial equation and a two-channel conduction model obeying the small polaron hopping mechanism, respectively. A very low activation energy in the range of 10–12 meV is observed due to smaller-sized particles. The presence of ZnO drives the hopping mechanism from adiabatic in LSMO to become non-adiabatic in the composites and enhances the maximum temperature coefficient of resistance. 80% LSMO-20% ZnO (by weight ratio) composite shows a maximum TCR of −29.81%/K at 248 K, which makes it a potential candidate for several applications in sensing devices. The Curie temperature of the material decreases with the increase in ZnO content in the sample. The results of this study also confirm the existence of correlation between the electrical and magnetic properties of LSMO. [ABSTRACT FROM AUTHOR]

Noble-gas implantation was used to introduce defects in n-type degenerate ScN thin films to tailor their transport properties. The electrical resistivity increased significantly with the damage levels created, while the electron mobility decreased regardless of the nature of the ion implanted and their doses. However, the transport property characterizations showed that two types of defects were formed during implantation, named point-like and complex-like defects depending on their temperature stability. The point-like defects changed the electrical conduction mode from metallic-like to semiconducting behavior. In the low temperature range, where both groups of defects were present, the dominant operative conduction mechanism was the variable range hopping conduction mode. Beyond a temperature of about 400 K, the point-like defects started to recover with an activation energy of 90 meV resulting in a decrease in resistivity, independent of the incident ion. The complex-like defects were, therefore, the only remaining group of defects after annealing above 700 K. These latter, thermally stable at least up to 750 K, introduced deep acceptor levels in the bandgap resulting in an increase in the electrical resistivity with higher carrier scattering while keeping the metallic-like behavior of the sample. The generation of both types of defects, as determined by resistivity measurements, appeared to occur through a similar mechanism within a single collision cascade. [ABSTRACT FROM AUTHOR]

Mica waste, a type of commercial waste produced in bulk quantities by the mica mining industry, was processed and added to Natural Rubber Latex Foams (NRLF) made of centrifuged and creamed latex. Following the Dunlop method, NRLF composites with various Processed Mica Waste (PMW) loadings (0, 2, 4, 6, 8, and 10 Phr) were prepared, and the thermo-physical characteristics were compared. Thermal conductivity, electrical resistivity of NRLF against the latex type and mica loading were compared for the first time. NRLFs prepared using creamed latex exhibit 33 and 50 μm (width and height) cell diameter, 3 ibf hardness, 281 % swelling index improvements and 0.05 Wm−1K−1 thermal conductivity, and 1 °C glass transition temperature (Tg) reductions than centrifuged NRLF and indistinguishable electrical resistivity. With the addition of mica (0–10 Phr), both NRLF types showed a similar ascending trend in hardness (42 ibf), water absorption (16 %), Tg (7 °C), thermal conductivity (0.54 Wm−1K−1), electrical resistivity (69 × 103 Ω m) with decreasing gel time (3 min) and swelling index (550 %). The key objective of this research was to prepare PMW-filled NRLF and compare structural, electrical and thermo-physical properties, for the first time, against mica content and latex type.

In this study, hybrid functional fillers were used to create an electrical network that is used to develop self-damage sensing ability within conventional cementitious mixtures. This electrical network was used to examine the self-sensing properties of cementitious composites under different loading scenarios such as compression, splitting tensile, and cyclic loading for three ages, those are 7, 14, and 28. With the help of a single type of functional filler or fiber, the self-sensing capabilities of the majority of previous works are demonstrated. This study incorporates two types of functional fillers for sustainability and low cost: micro-scale carbon fibers (CF) and waste iron (Ir) powder in the form of microparticles. The purpose of the current work is to fill up the subject’s gap using two different types of functional fillers as a hybrid form. Three hybrid proportions of a micro-scale CF (vol% of mixture) and waste iron powder (Ir) (wt% of cementitious materials) are utilized. These are (0.33, 15), (0.67, 10), and (1.00, 5), respectively. Unlike carbon-based materials, polyvinyl alcohol is used as a mechanical reinforcing fiber 2% by volume of the cementitious mixture. Additionally, a control combination without any fillers has been created. The electrical resistivity of the fabricated samples was monitored during various loading applications for every second to confirm their self-sensing capabilities. Regarding the fractional change in electrical resistivity, the self-sensing behavior was superior for mixes containing high dosages either of waste iron powder or CF in the same hybrid matrix. Quite the contrary to that, the piezoresistivity was modest in the middle hybrid ratio.

A current-limiting and consequent direct current (DC) arc interruption requires an increase in arc resistance r a r c for a DC fuse. Flattery silica (SiO2) sand has been used as an arc quenching medium in fuses for decades. However, there are few reports about a novel arc quenching medium which enables more r a r c increases compared to flattery SiO2 sand. This paper uniquely selected a novel arc quenching medium based on the following material properties: (1) electrical resistivity and thermal conductivity in the solid phase, (2) the possibility of r a r c increasing in the gas phase, (3) the possibility of electrical insulation after re-solidification, and (4) the cost of materials. As a result, we originally selected a powder mixture of silicon-nitride (Si3N4) and flattery SiO2 sand as a promising novel arc quenching medium. Therefore, DC interruption experiments were performed using a Si3N4/flattery SiO2 sand powder mixture under different Si3N4 concentration conditions. As a result of 1000 A DC arc quenching experiments, the utilization of Si3N4 powder with the flattery SiO2 sand successfully increased the arc resistance r a r c during the arc quenching process. The increasing Si3N4 concentration exhibited a further increase in r a r c during the arc quenching process. As a result of the r a r c increase, the arc quenching time was significantly shortened to 30 ms for 30 wt.% Si3N4 conditions from 54 ms for the SiO2 sand conditions. In addition, utilization of Si3N4 powder achieved high insulation resistance over few MΩ after DC arc interruption. The above results clearly indicate that utilization of Si3N4 powder with flattery SiO2 sand can increase the DC interruption performance of the fuse. [ABSTRACT FROM AUTHOR]

BACKGROUND: Conductive biomaterials are considered potential candidates for transmitting electrical signals for myocardial repair. Combining cell-based or cellfree strategies with conductive biomaterials to replenish cardiomyocytes and/or restore electrical signaling pathways is a promising approach for cardiac repair. OBJECTIVE: To evaluate the effect of polypyrrole-chitosan conductive composite hydrogel on cardiac function in rats with myocardial ischemia-reperfusion injury. METHODS: The polypyrrole-chitosan conductive composite hydrogel was prepared by chemical oxidative polymerization. The micromorphology, biocompatibility and conductivity of the hydrogels were characterized. Thirty adult SD rats were selected to establish a myocardial ischemia-reperfusion injury model by clamping the left anterior descending branch of the heart and then releasing it. After 21 days of modeling, the rats were divided into three groups by the random number table method: Normal saline was injected into the left ventricular infarction area and infarction margin area in the blank group. Chitosan hydrogel was injected into the left ventricular infarction area and infarction margin area in the ordinary hydrogel group. The polypyrrole-chitosan conductive composite hydrogel was injected into the left ventricular infarction area and infarction margin area, with 10 rats in each group. The corresponding time points after modeling were set, and cardiac mechanical function (echocardiogram, pressure-volume analysis), cardiac electrophysiology (electrocardiogram, programmed electrical stimulation, optical mapping technology, microelectrode array technology, eight-lead electrocardiogram, and electrical resistivity of the scar area) and cardiac histology were detected. RESULTS AND CONCLUSION: (1) There were a lot of pores on the surface of the conductive composite hydrogel, and the conductivity was (3.19±0.03)× 10-3 mS/cm, which had good biocompatibility co-cultured with smooth muscle cells. (2) After 105 days of modeling, echocardiogram and pressure-volume analysis showed that compared with the blank group and the ordinary hydrogel group, the conductive composite hydrogel could significantly improve the contractile function of the heart of rats with myocardial ischemia-reperfusion injury. The results of electrocardiogram, programmed electrical stimulation, optical mapping technology, microelectrode array technology, eight-lead electrocardiogram, and electrical resistivity of the scar area examination at 105 days after modeling displayed that, compared with the blank group and the ordinary hydrogel group, the conductive composite hydrogel could significantly improve the electrical conduction function of the heart of rats with myocardial ischemia-reperfusion injury and reduce the occurrence of arrhythmia. Masson staining of heart tissue at 105 days after modeling exhibited that there were different degrees of fibrosis in the myocardial infarction area of the three groups. Compared with the normal saline group and the ordinary hydrogel group, the conductive hydrogel group had more normal myocardial tissue and less fibrosis in the myocardial infarction area. (3) The results verify that polypyrrole-chitosan conductive composite hydrogel may promote the repair of infarcted heart after ischemia-reperfusion injury by increasing the electrical conduction velocity of infarct scar area tissue, increasing scar thickness, enhancing synchronous cardiac contraction, and reducing damaged tissue. [ABSTRACT FROM AUTHOR]

The rare-earth orthoferrite perovskite high-entropy ceramics constitute a recently discovered class of high-entropy oxides featuring single-phase structures. However, the practical application of rare-earth orthoferrite high-entropy ceramics is impeded by high dielectric loss and conductivity. Here, rare-earth orthoferrite high-entropy ceramics Bi 0.2 La0 0.2 Y 0.2 Dy 0.2 Tb 0.2 Fe 1-x Ti x O 3 (x = 0, 0.025, 0.05, and 0.075) were fabricated using the conventional solid-phase method. The ceramic with x = 0.025 shows a reduction in grain size and higher electrical resistivity (256 kΩ). Furthermore, an increase in capacitances at grain boundaries is reported in ceramics with x values exceeding 0.025. The results show that donor doping introduces the presence of free electrons, subsequently enhancing polarization at grain boundaries. This non-equimolar high-entropy approach contributes to a deeper understanding of the unique properties exhibited by rare-earth orthoferrite high-entropy materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Seismic and electromagnetic explorations are two of the most successful geophysical applications for understanding the subsurface earth, and the joint interpretation of seismic and electromagnetic survey data can help to better characterize the rocks because they contain independent and complementary information about the rocks. However, the success of the joint interpretation depends on the understanding of the correlations between the elastic and electrical rock properties and their influencing factors. Confining pressure is an important geological parameter that has been found to give rise to linear elastic–electrical correlations in sandstones. However, it is still poorly known what controls the slopes of the pressure-dependent linear correlations, even though slope is one of the most important parameters determining the linear correlation. We make artificial sandstones with controlled porosity and permeability, respectively, and measure their pressure-dependent elastic (electrical resistivity) and electrical (P -wave velocity) properties simultaneously, as well as porosity. We show that the slopes of the measured electrical resistivity versus P -wave velocity as an implicit function of confining pressure correlate positively with the compliant porosity in all the samples. The results not only reveal the petrophysical parameter that controls the slopes of the pressure-dependent linear elastic–electrical correlations in sandstones, but also provide a basis for the discrimination of the slope-controlling parameter from the simultaneously measured elastic and electrical properties. [ABSTRACT FROM AUTHOR]

AlN ceramics exhibit good physical and chemical properties and are ideal materials for the dielectric layer of electrostatic chucks. However, they cannot generate a strong J−R-type electrostatic adsorption force because of their high resistivity. Therefore, adding other substances is necessary to regulate the electrical properties and enable their application. In this study, AlN ceramics were prepared using hot-pressed sintering with 0.2 wt% CaO as an additive at a sintering temperature range of 1700–1900 °C. The effects of CaO doping on the phase composition, microstructure, electrical properties, and thermal conductivity of the AlN ceramics were systematically investigated. The addition of CaO not only enhanced the sintering process of the AlN ceramics, but also significantly reduced the electrical resistivity and increased the thermal conductivity. The relative density of CaO-doped AlN ceramics reached 98.88 % at 1700 °C, with a thermal conductivity of 81.51 W m−1•K−1. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and AC impedance spectroscopy were used to analyse the impurities and defects in the AlN ceramics. The lattice parameters and fitting grain resistance indicated that the CaO-doped AlN presented a higher lattice oxygen concentration, increasing the concentration of Al vacancies and electrons. Moreover, the level of dissolved oxygen could be controlled by altering the sintering temperature, resulting in AlN ceramics with electrical resistivity ranging from 8.1 × 106 to 1.7 × 1012 Ω cm. Further research was conducted to investigate the effect of the electrical resistivity of AlN ceramics on the J−R-type electrostatic adsorption force, and it was found that AlN ceramics with a specific resistivity of 109 Ω cm exhibited the highest electrostatic adsorption of 351.7 g/cm2. [ABSTRACT FROM AUTHOR]

Xinjiang has a temperature difference of 20°C between day and night, interannual temperature difference of 50°C, the control of the temperature cracks in mass concrete becomes difficult. Although low-heat portland (P·LH) cement concrete containing fly ash (FA) can reduce hydration heat, the mismatch between its mechanical and thermal properties is still not fully resolved. An attempt to explore the effect of FA on the competitive hydration reaction of C3A and C3S at super-early ages, and how this effect changes the physical and chemical properties of hardened cement pastes by electrical resistivity and zeta potential and common microstructure test methods, and to provide a theoretical basis for optimization of mechanical and thermal properties of P·LH cement concrete with FA. Results showed that in the fast dissolution stage, a numerous {Ca6[Al(OH)6]224H2O}6+ ions and a very small amount of H3SiO4−/H2SiO42− ions were formed, and incorporating 20%, 30%, 40% FA primarily inhibited the Al(OH)63− hydration and the {Ca6[Al(OH)6]224H2O}6+ generation, resulting in the generation time of AFt in comparison with pure cement, respectively, delayed by 44%, 140%, and 524%. This phenomenon decreased the nucleation and crystallization growth rate of AFt and Ca(OH)2 in the induction stage, and reduced the consumption of gypsum in the acceleration stage. Hence, monosulfoaluminate did not exist for pastes with more than 30% FA, and the number of particles involved in the reaction for the P·LH cement stone with 20%, 30%, and 40% FA decreased by 4.0%, 46.5%, and 52.0% in the deceleration stage compared with the pure cement. The research results can provide a theoretical reference for modifying chemical properties of FA to meet the matching of mechanical strength and thermal of P·LH cement. [ABSTRACT FROM AUTHOR]

This study examined the effect of hydrogels containing urease and proteins on the self-healing of cracked cementitious materials. The encapsulation of proteins and urease decreased the absorption of hydrogels. It was shown that proteins were able to release from hydrogels into the surrounding cementitious matrix. TGA, FTIR, and SEM showed increased calcium carbonate formation, and optical imaging indicated enhanced crack filling in the samples with hydrogels containing urease and proteins, compared to the control sample. This is attributed to the enhanced autogenous healing provided by water absorption/desorption of hydrogels as well as enzymatic reaction. Calcite was shown to be the dominant polymorph of calcium carbonate in the healing products. Interestingly, the mechanical strength regain was markedly higher in the samples with hydrogels containing urease and proteins compared to the control sample. Improved interfacial strength at the microstructure level enhances cohesion within healing products and adhesion between the healing products and crack surface, leading to overall increased mechanical strength regain. The electrical resistivity results were shown to be in agreement with the mechanical strength regain. [ABSTRACT FROM AUTHOR]

A-, and B-site multiple-doped Ca 0.97 Y 0.01 La 0.01 Yb 0.01 Mn 1–2x Nb x Mo x O 3 was studied for improving its thermoelectric thermoelectric performance. Samples were prepared from planetary milled precursors and sintered at 1310ºC for 12 h. XRD showed that sintered samples are nearly single phase, with small amounts of CaMn 2 O 4. SEM analysis revealed that grain size decreases with Nb and Mo content, leading to lowered electrical resistivity, reaching 6.1 mΩ cm at 800ºC in x = 0.03 samples, 60% lower than that of pristine samples. The highest Seebeck coefficient for doped samples has been obtained for x = 0.005, 210μV/K at 800ºC. A high power factor (0.46 mW/K2 m at 800ºC) has been reached for x = 0.01 samples. However, thermal conductivity did not significantly vary with composition, leading to ZT∼0.27 at 800ºC for x = 0.005 samples, among the best reported in the literature. These results suggest that multi-doping approach opens new paths for integrating calcium manganite-based materials in thermoelectric modules for power generation at high temperatures. [ABSTRACT FROM AUTHOR]

The effect of addition of various metal carbides on the electrical, thermal, and mechanical properties of porous SiC ceramics was investigated. The results showed a decrease in the electrical resistivity from 1.2 × 102 to 1.3 × 10−3 Ω‧cm and thermal conductivity from 14.2 to 3.6 W.m−1K−1 whereas the compressive strength increased from 12.7 to 21.1–81.1 MPa at ∼60.2% porosity. The decrease in electrical resistivity and thermal conductivity was caused by the introduction of conductive carbides and multiple heterophase interfaces, respectively, in the porous ceramics. The electrical and thermal conductivities and compressive strength of porous SiC-based ceramics, processed with a SiC-B 4 C-VC-ZrC-NbC composition, were 8.0 × 102 Ω−1‧cm−1, 3.6 W‧m−1K−1, and 58.0 MPa, respectively. Therefore, it is proven that the electrical, thermal, and mechanical properties of porous SiC ceramics can be tuned over a wide range by adding a suitable combination of metal carbides. [ABSTRACT FROM AUTHOR]

Because of their excellent insulation performance and processing properties, polymers are widely used in electrical and electronic applications. However, their further applications are severely constrained by their extremely low intrinsic thermal conductivity. Boron nitride (BN), which has high thermal conductivity and ideal insulation properties, is commonly used as a filler for improving the thermal conductivity of polymers. However, the high chemical inertia of the surface of BN makes it difficult to achieve an interconnection of BN sheets when building a three-dimensional (3D) BN skeleton in a polymer. In this study, urea melt pore preparation (UMPP) was used to fabricate a 3D BN skeleton. Urea was infiltrated into the BN skeleton to minimize the interfacial thermal resistance among the BN flakes and to join BNs. When the volume of a BN is 10 %, the thermal conductivity of the BN/epoxy composites is 3.15 W/(m·K). When the BN volume is 80 %, the thermal conductivity of BN/epoxy can reach 13.65 W/(m·K), which is 6500 % of pure epoxy resin. Additionally, the skeleton exhibits a remarkable mechanical strength capable of supporting weights up to 50,000 times its own, which facilitates easier handling and operation. The electrical resistivity volume of the UMPP composite is as high as that of the pure epoxy, whereas the dielectric loss is lower than that of pure epoxy. This study provides a new method for reducing internal interface thermal resistance of a skeleton formed by thermal conductive fillers with high chemical inertia such as boron nitride. [ABSTRACT FROM AUTHOR]

The additive manufacturing of components using material extrusion (MEX) enables the integration of several materials into one component, including functional structures such as electrically conductive structures. This study investigated the influence of the selected additive MEX process on the resistivity of MEX structures. Specimens were produced from filaments and granules of an electrically conductive PLA and filled with carbon nanotubes and carbon black. Specimens were produced with a full-factorial variation of the input variables: extrusion temperature, deposition speed, and production process. The resistivity of the specimens was determined by four-wire measurement. Analysis of the obtained data showed that only the extrusion temperature had a significant influence on the resistivity of the MEX specimens. Furthermore, the impact of the nozzle diameter was evaluated by comparing the results of this study with those of a previous study, with an otherwise equal experimental setup. The nozzle diameter had a significant influence on resistivity and a larger nozzle diameter reduced the mean variance by an order of magnitude. The resistivity was lower for most process parameter sets. As the manufacturing process had no significant influence on the resistivity of MEX structures, it can be selected based on other criteria, e.g., the cost of feedstock. [ABSTRACT FROM AUTHOR]

To study the influence of coal mining on the water richness overlying strata in the mining area using time-lapse electrical monitoring technology, four dataset acquisitions were completed with the same acquisition method, equipment, parameters, and processing flow. According to the characteristics of the data, major problems such as topographic correction, high-precision denoising, spatial and temporal normalization, and resistivity data inversion have been solved. Precise tomographic imaging was achieved through high-precision data processing and difference inversion. The results show that the electrical stratification characteristics of the overlying soil and rock layers are clear, the resistivity from the surface down gradually increases, and the electrical layers are not uniform locally. During mining, the overlying strata are affected by mining, the electrical resistivity of the underlying aquifers increased to varying degrees, and the fluctuation of electrical resistivity increased while the aquifer's water content decreased. After mining, the overlying aquifer has the phenomenon of 'reduced resistivity and water recovery'. After a period of time, the overlying soil disturbance and overlying rock failure zone will gradually tend to be stable. Meanwhile, the aquifer structure and water content will also gradually recover. Our results could provide guidance for water resources protection in this region. [ABSTRACT FROM AUTHOR]

Ultrawide bandgap (UWBG) semiconductors inherently exhibit very high electrical resistivities. This property presents not only challenges in probing their electrical transport properties but also difficulties to fabricate, understand, and characterize the electrical properties of metal contacts on these materials. Here, we report the measurements and analysis of the applied electric field dependence of photocurrent to reveal the effect of metal contacts on the transport properties of highly resistive h-BN. Our results indicate that even for h-BN with a room temperature resistivity as high as 1014 Ω cm, the as-deposited metal contact is not a completely blocking type as commonly assumed in previous analyses for other large bandgap insulating materials. By modifying the boundary condition between the metal/semiconductor interface, a quantitative description has been obtained, which can be used to determine if the metal contact is Ohmic or blocking type. This quantitative description should be applicable to all UWBG semiconductors with extremely high electrical resistivities. The work also provides a better understanding of how the metal contact type affects the transport properties of UWBG semiconductors in general. [ABSTRACT FROM AUTHOR]

Reinforced concrete (RC) is one of the most widely used building materials. However, RC, especially in coastal seaside or humid environments, can suffer reinforcement corrosion with the result that the reinforcement fails to perform its function over time. The effect of a retarder additive used to eliminate loss of consistency in hot, windy and humid weather on the corrosion of RC elements was investigated in this work. Four different concrete types were assessed, with 0%, 1%, 1.5% and 2% additions of the chemical additive. Along with accelerated corrosion and pressure tests, physical properties such as electrical resistivity, water absorption, porosity, unit weight and capillary water absorption were also determined. The results of this work indicate that the use of up to 2% of the setting retarder did not pose a problem in terms of the physical and mechanical properties of the concrete. However, in terms of the frequently encountered corrosion problem, the use of 1.5% is more appropriate. Many chemical additives are used for different purposes in concrete and it is suggested that, alongside physical and mechanical properties, durability characteristics should also be examined when determining the suitable ratios of these additives. [ABSTRACT FROM AUTHOR]

The Mongol‐Okhotsk suture and the Adaatsag ophiolite belt are associated with the closure of the Mongol‐Okhotsk paleo‐ocean and are located within the Central Asian Orogenic Belt (CAOB) and Mongolia. The suture zone is flanked by volcanic‐plutonic belts that host significant metallogenic zones, containing deposits of copper and gold. The tectonic evolution of this region is not fully understood and the lithospheric structure has been poorly studied. We analyze magnetotelluric data and generate a model of the electrical resistivity distribution across this region. Whereas the northern segment has a sharp transition from a high‐resistivity upper crust to a low‐resistivity lower crust, as observed beneath the Hangai Dome, the southern segment does not show this transition. A wide, low‐resistivity zone (1–100 Ωm) imaged in the crust and lithospheric mantle is coincident with the Mongol‐Okhotsk suture and ophiolite, revealing a clear and significant lithospheric‐scale feature. Across the profile, numerous narrow, vertically oriented, low‐resistivity features (1–100 Ωm) are spatially associated remarkably well with the proposed boundaries of tectonic domains. These results confirm ideas about the development of the CAOB. Some of these low‐resistivity features are beneath the surface locations of large mineral zones, and likely represent fossil fluid pathways. We show congruent seismic velocity models for comparison and the results show a large‐scale low‐velocity anomaly (decrease of 2%–3%) that correlates with the location of the low‐resistivity anomaly below the Mongol‐Okhotsk suture. The geophysical results, combined with geological and geochemical data, provide insights into the structure of this region and help shed light on unanswered questions. Plain Language Summary: When the ancient Mongol‐Okhotsk ocean closed, due to subduction from tectonic re‐arrangement, it left the Mongol‐Okhotsk suture zone and the Adaatsag ophiolite as a trace of its location. Similarly, other tectonic boundaries are hypothesized to exist from terrane accretion across the Central Asian Orogenic Belt (CAOB) and Central and Southern Mongolia, which is located between the Siberian and North China cratons. This region is also rich in economically significant copper and gold deposits. The tectonic evolution of this region and especially the lithospheric structure is not fully understood and has been poorly studied. We analyze magnetotelluric data and generate a model of the electrical resistivity distribution. Additionally, we show models of the seismic velocity for comparison. Examining multiple complementary geophysical models helps to reduce interpretation uncertainty. Anomalies are observed in both models (e.g., low resistivity and low velocity). The suture zone is proven to be a strong lithospheric‐scale boundary. The proposed boundaries of tectonic domains are also imaged, confirming ideas about the development of the CAOB, and solving some controversies. Key Points: Lithospheric‐scale, wide, low‐resistivity zone revealed below the ophiolite belt associated with the closure of the Mongol‐Okhotsk oceanVertical, narrow low‐resistivity features aligned with proposed tectonic boundaries and locations of large mineral zones (copper and gold)The northern part of central Mongolia has a sharp mid‐crustal transition from high to low resistivity, whereas the southern part does not [ABSTRACT FROM AUTHOR]

In underground filling mining, freshly prepared cemented gangue-fly ash backfill (CGFB) slurries are typically piped into the gobs. The rheological properties of backfill slurry during pipeline transportation have a direct impact on the transportation characteristics, which in turn affect pipeline blockage and wear. In this paper, the rheological behavior and viscoelastic-plastic properties of CGFB during pipeline transportation are investigated. The effects of different solid content and cement content on resistivity were tested experimentally, and their viscoelasticity and plasticity were analyzed. The results show that with the increase in solid phase content and cement content, the viscosity, yield stress, and energy storage modulus of the materials showed an increasing trend. The viscosity and yield stress of the material both increased, reaching 32.77% and 51.22%, respectively. It was found by the dynamic shear test that in the low-strain region, the material showed a more significant elastic nature of the solid, while in the high-strain region, the viscosity of the material gradually increased. Cement has a substantially lower resistivity than fly ash and gangue, and with the increase in solid concentration, the resistivity of the material shows an increasing trend. With the increase in cement content, the resistivity generally shows a decreasing trend, but it should be noted that the resistivity change trend may tend to stabilize after the cement content exceeds 12%. The study's findings can aid in understanding the rheological properties of CGFB and its viscoelastic-plastic behavior during the underground filling and conveying process, which can provide a reference basis for research and application in related fields. [ABSTRACT FROM AUTHOR]

We present a synthetic multi‐scale, multi‐physics dataset constructed from the Kimberlina 1.2 CO2 reservoir model based on a potential CO2 storage site in the Southern San Joaquin Basin of California. Among 300 models, one selected reservoir‐simulation scenario produces hydrologic‐state models at the onset and after 20 years of CO2 injection. Subsequently, these models were transformed into geophysical properties, including P‐ and S‐wave seismic velocities, saturated density where the saturating fluid can be a combination of brine and supercritical CO2, and electrical resistivity using established empirical petrophysical relationships. From these 3D distributions of geophysical properties, we have generated synthetic time‐lapse seismic, gravity and electromagnetic responses with acquisition geometries that mimic realistic monitoring surveys and are achievable in actual field situations. We have also created a series of synthetic well logs of CO2 saturation, acoustic velocity, density and induction resistivity in the injection well and three monitoring wells. These were constructed by combining the low‐frequency trend of the geophysical models with the high‐frequency variations of actual well logs collected at the potential storage site. In addition, to better calibrate our datasets, measurements of permeability and pore connectivity have been made on cores of Vedder Sandstone, which forms the primary reservoir unit. These measurements provide the range of scales in the otherwise synthetic dataset to be as close to a real‐world situation as possible. This dataset consisting of the reservoir models, geophysical models, simulated time‐lapse geophysical responses and well logs forms a multi‐scale, multi‐physics testbed for designing and testing geophysical CO2 monitoring systems as well as for imaging and characterization algorithms. The suite of numerical models and data have been made publicly available for downloading on the National Energy Technology Laboratory's (NETL) Energy Data Exchange (EDX) website. [ABSTRACT FROM AUTHOR]

Small-scale mining (SSM) is responsible for almost all the production of non-metallic minerals in the world and represents around 80% of the mining in Brazil. The lack of direct geological information increases the level of uncertainty associated with the exploratory process, compromises mine planning, limits mineral extraction, and contributes to maximizing environmental issues. In this research, near-surface geophysical methods, including Electrical Resistivity, Capacitive Resistivity, Ground Penetrating Radar (GPR), and Transient Electromagnetic (TEM), were applied to characterize a marble deposit in an SSM located in the Campos do Jordão region, São Paulo state, southeast Brazil. The geophysical methods used provide indirect information about the subsurface geology based on the contrast in electrical and electromagnetic properties. Resistivity results show the efficiency of locating marble deposits, as well as fracture zones. GPR profiles allowed for the investigation of the structural heterogeneities in the subsurface. Geophysical data and lithological information from drill holes were integrated into Micromine software and guided the development of a geological model and a conceptual pit model. The information inferred from the pit modeling allowed us to analyze the potential of the deposit and should be used to assist in developing sustainable mining planning. The results of this work demonstrate that the investment in geophysical research can support the modernization of an SSM and contribute to more sustainable and productive mining. [ABSTRACT FROM AUTHOR]

Hybrid fiber‐reinforced cementitious composites (HyFRCC) consisting of polyethylene (PE) and carbon fiber (CF) have potential for use in advanced composite materials by integrating high mechanical performance with smart functions based on electrical properties. However, an evaluation of the electrical and fracture properties of HyFRCC has not yet been reported. An orthogonal experimental design was used to investigate the effect of the water‐to‐binder (w/b) ratio and volume fraction of PE and carbon fiber on the electrical properties and fracture behavior of HyFRCC in this paper. The results show that the w/b ratio plays a major role in controlling the electrical resistivity of HyFRCC. The larger the amount of hybrid fibers added, the higher the w/b ratio needed. In particular, the PE fiber must not exceed 1.5 vol% to obtain HyFRCC with low electrical resistivity. Carbon fiber has a significant effect on the initial fracture toughness of HyFRCC, while PE fiber determines its unstable fracture toughness. A hybrid fiber system containing 1.0 vol% PE fiber and 0.5 vol% carbon fiber at a w/b ratio of 0.35 was used to reach a compatible electrical property and fracture behavior of HyFRCC. The results of this work provide a novel approach for designing and developing multifunctional cementitious composites, which would be a promising building material for structural strengthening and protection of steel corrosion as well as structural health monitoring. [ABSTRACT FROM AUTHOR]

Using an integrated method, four distinct hydraulic flow units (HFUs) were produced from the hydrogeological layers of Ikot Abasi in southern Nigeria. The SMLP, which produced results comparable to those of the discrete rock typing (DRT) technique deploying flow zone indicator (FZI), was used to define and classify the geologic unit (GU) of the aquifer into sections denoted by isophysical and isochemical hydro-sand beds as well as sections with similar hydrodynamic characteristics. The results of an electrical resistivity investigation led to the discovery of three to four economically viable geo-electric strata for groundwater. The goal of this study is to economically valorize the HFUs within the GU for efficient groundwater management. Economic aquifer sand beds in layer two were identified and their resistivity ranged from 26.3–3576.5 Ωm with an average of 764.3 Ωm and thickness ranged from 2.9–262.6 m with a mean value of 61.7 m. Similarly, the estimated ranges of resistivity values and values of thickness of the economic aquifer sand beds in layer three were 58.0–3588.8 Ωm (mean: 840.5 Ωm) and 26.7–212.1 m (mean: 80.0 m), respectively. The result from DRT gave four HFUs, which conformed to the result of SMLP. The four HFUs christened as HFU1-HFU4 are identified by tanθ/slope with each corresponding to 2.083, 1.136, 0.483, and 3.101, respectively. The corresponding value for angle θ in degrees was estimated at 64 (superconductor), 47 (conductor), 26 (semi-conductor) and 72 (superconductor), respectively. According to values of ranking efficiency, the delineated HFUs can be classified, respectively, as good, fair, poor and good. The aquifer system identified to be perfectly heterogeneous has good hydrodynamic prospect, which is paramount in groundwater flow management and contamination monitoring. [ABSTRACT FROM AUTHOR]

Western Desert region between Cairo and Fayoum in Egypt is a geologically interesting area due to its active seismicity status and the continuous bidirectional urban expansions ongoing northward and southward growth. This work aims to develop a geological model of the region by combining magnetic intensity data (aeromagnetic) and potential field data (airborne gravity) with magnetotelluric (MT) data to offer decision-makers an additional evaluation tool for long-term future planning. Applying a number of filters to aerial gravity and magnetic data allowed us to calculate the subsurface density distribution and structure of the area between Cairo and Fayoum. In addition, the surface of the crust was imaged down to a depth of 6 km using a 3-D inversion of gravity data. Magnetotelluric data were gathered at eight locations over the NS-extended Cairo-Fayoum Road profile. MT data were inverted in 2-D to generate a resistivity model that defines the subsurface structure of the researched region. The subsurface geometry in the MT-derived resistivity model agrees with the results of airborne potential measurements, and no consideration was given to any faults that may have been undetected from the potential maps. Long-term seismological observations indicated that the likely active sources of earthquakes are limited to the recognized main faults and that the ongoing "1185 buildings" construction project did not and will not cause unanticipated seismicity. The paper concludes that urban growth is secure so long as the earthquake codes are rigorously considered while planning civil projects. The northern study region must be regularly monitored for induced seismicity. On the Cairo-Fayoum Road's western side, the middle sector of the study area is the safest place for future civil developments. [ABSTRACT FROM AUTHOR]

Background: Comprehensive datasets quantifying the coupled thermo-mechanical and electrical properties of shape memory alloys (SMAs) are lacking, as are standardized techniques for robust characterization. This hampers accurate modeling and design of SMA-based components. Objective: This work develops an automated experimental system to enable simultaneous measurement of stress-strain-temperature behavior and electrical resistivity evolution in NiTi SMA wires under controlled stress conditions. Methods: Customized test frames apply precise mechanical stresses while allowing for in situ electrical measurements and infrared imaging during complete thermal cycling protocols. Specialized instrumentation including a Keithley 2002 multimeter, Agilent E3631A programmable power supply, and FLIR A615 thermal camera are integrated with LabVIEW-based software routines for complete automation of the characterization process. Rigorous metrology principles are implemented throughout the measurement procedure to improve accuracy, repeatability, and consistency compared to prior manual techniques. Results: Extensive datasets are generated which reveal pronounced stress-dependencies in key SMA material parameters including transformation temperatures, recoverable strain, and electrical resistivity. A 3D regression model describes the comprehensive relationship between resistivity, temperature, and applied stress across the entire characterization domain. Conclusions: The automated measurement framework and methodology establishes a foundation for high-fidelity, reliable acquisition of coupled SMA property data. This will enable more accurate modeling and design of components and systems incorporating SMA actuation or sensing functions. [ABSTRACT FROM AUTHOR]

Accurate characterization and monitoring strategies are essential for designing and implementing remedial programs for sites polluted with dense non-aqueous phase liquids (DNAPLs). Electrical resistivity tomography (ERT) is a widely used geophysical technique for mapping subsurface features and processes of interest, and exhibits desirable characteristics for DNAPL sites due to its ability to gather large volumes of continuous subsurface information in a non-invasive, cost-effective and time-efficient manner. However, ERT measured only from the surface suffers from poor imaging quality with depth. Enhanced ERT imaging can be obtained via electrodes deployed on the surface and within horizontal boreholes, but so far it has only been investigated for 2-D imaging. This study evaluates the potential of 3-D surface-to-horizontal borehole (S2HB) ERT configurations for imaging 3-D DNAPL source zones. Laboratory tank experiments were first conducted with a 3-D S2HB ERT configuration, which consisted of a surface grid and a single borehole line of electrodes, being used to monitor DNAPL migration within porous media. Results demonstrate that 3-D S2HB ERT with a single borehole provides improved sensitivity at depth, and therefore enhanced imaging compared to conventional 3-D surface ERT. Further tank experiments were performed to assess the performance of single borehole S2HB ERT when (i) the distance between surface and borehole is increased, and (ii) additional horizontal boreholes are included. The S2HB ERT with a single borehole significantly outperforms surface ERT at larger depths, and performs comparably to S2HB ERT using multiple boreholes. This study suggests that 3-D S2HB ERT with a single borehole can provide the enhanced imaging ability needed to map DNAPLs, while also being relatively practical for implementation at field sites. [ABSTRACT FROM AUTHOR]

We report the results of the characterization of the electrical resistivity of selected ceramic materials, namely aluminum nitride (AlN), silicon nitride (Si3N4), beryllium oxide (BeO), yttrium oxide (Y2O3), and non-ceramic silicon dioxide (SiO2), which are candidates for packaging silicon carbide (SiC) sensors and electronics that can operate at temperatures beyond 800°C. Samples of thesematerials were thermally cycled twice to 1200°C in nitrogen while the bulk and surface resistivities were measured in situ. Although the resistivity values of all samples dropped with increasing temperature, BeO maintained the relatively highest bulk and surface resistivity values at 1200°C of 28 and 34 kΩ cm, respectively, while AlN had the lowest values at 6.8 and 0.64 kΩ cm. In terms of viability for packaging SiC sensors for >800°C operation, AlN and Si3N4 are the choice candidates due to their lowest mismatches in the coefficient of thermal expansion with SiC. However, the relative resistivity stability of Si3N4 over AlN makes it a promising candidate, even with its lower thermal conductivity relative to AlN. [ABSTRACT FROM AUTHOR]

Bismuth layer-structured ferroelectrics (BLSFs) are widely demanded in high-temperature piezoelectric sensors, while their low piezoelectricity-induced low sensitivity of piezoelectric sensors is not appropriate for practical operation conditions. Texturing is an effective way to engineer the performance of piezoelectric ceramics by aligning the polar vectors and increasing poling efficiency. Herein, chemical substitution together with the hot-pressing technique is utilized to improve the piezoelectricity of BTN-based ceramics. Characterizations demonstrate that the grains with (100) orientation as shown in the {001} pole figure and the improved domain switching are the main causes of excellent ferroelectricity (P r ∼17.7 μC/cm2) and large piezoelectric coefficient (d 33 ∼27 pC/N) in the textured BCTNTW-Per ceramic. The BCTNTW-Per ceramic also exhibits high T C (890 °C), low dielectric loss, high electrical resistivity (1.6 ×105 Ω•cm at 600 °C), and excellent thermal stability, demonstrating that the combination of the hot-pressing technique and traditional doping strategy is an effective way to prepare high-performance of BLSFs. [ABSTRACT FROM AUTHOR]

The Ningdong coalfield has played a pivotal role in advancing local economic development and meeting national energy. Nevertheless, mining operations have engendered ecological challenges encompassing subterranean water depletion, land desertification, and ground subsidence, primarily stemming from the disruption of coal seam roof strata. Consequently, the local ecosystem has incurred substantial harm. Water-preserved coal mining presently constitutes the pivotal technology in mitigating this problem. The primary challenge of this technique lies in identifying critical aquifer layers and understanding the heights of water-conducting fracture zones. To obtain a precise comprehension of the seepage patterns within the upper coal seam aquifer during mining, delineate the extent of water-conducting fracture zones, non-invasive geophysical techniques such as time-lapse electrical resistivity tomography (TL-ERT), magnetic resonance sounding (MRS), and spontaneous potential (SP) have been employed to monitor alterations within the shallow coalfield's aquifer throughout the mining process in the Ningdong coalfield. By conducting meticulous examinations of fluctuations in resistivity, moisture content, and self-potential within the superjacent strata during coal seam extraction, the predominant underground water infiltration strata were ascertained, concurrently enabling the estimation of the development elevation of water-conducting fracture zones. This outcome furnishes a geophysical underpinning for endeavors concerning local water-preserved coal mining and ecological rehabilitation. [ABSTRACT FROM AUTHOR]

Permafrost is a widespread phenomenon in the cold regions of the globe and is under‐represented in global monitoring networks. This study presents a novel low‐cost, low‐power, and robust Autonomous Electrical Resistivity Tomography (A‐ERT) monitoring system and open‐source processing tools for permafrost monitoring. The processing workflow incorporates diagnostic and filtering tools and utilizes open‐source software, ResIPy, for data inversion. The workflow facilitates quick and efficient extraction of key information from large data sets. Field experiments conducted in Antarctica demonstrated the system's capability to operate in harsh and remote environments and provided high‐temporal‐resolution imaging of ground freezing and thawing dynamics. This data set and processing workflow allow for a detailed investigation of how meteorological conditions impact subsurface processes. The A‐ERT setup can complement existing monitoring networks on permafrost and is suitable for continuous monitoring in polar and mountainous regions, contributing to cryosphere research and gaining deeper insights into permafrost and active layer dynamics. Plain Language Summary: Permafrost, frozen ground in cold regions, has significant impacts on the global environment. Monitoring of permafrost is crucial because it influences the global carbon cycle, hydrology, contaminant movement, and ecosystem stability. However, current monitoring systems have limitations, particularly in remote regions like Antarctica. To tackle this challenge, a new monitoring system, Autonomous Electrical Resistivity Tomography (A‐ERT), was introduced. A‐ERT is a geophysical technique that employs electrical signals to study ground freezes and thaws with high precision over time. Alongside this, open‐source processing tools were developed to process obtained A‐ERT data and efficiently extract essential information from large data sets. The developed A‐ERT system is robust, low‐cost, low‐power, and designed to operate in harsh conditions. Tested in Antarctica, our findings show that A‐ERT data combined with processing pipelines offers a valuable tool for examining freezing and thawing processes in extreme environments. The proposed setup can contribute to a network of autonomous permafrost monitoring systems, important for cryosphere research and advancing our understanding of climate change's impact on permafrost dynamics. Key Points: We present a robust low‐cost Autonomous Electrical Resistivity Tomography system for permafrost monitoring in polar and mountainous regionsWe introduce an open‐source tool for processing and inverting large data sets, enabling quick and efficient extraction of key informationField experiments conducted in Antarctica show high‐temporal‐resolution imaging of ground freezing and thawing dynamics [ABSTRACT FROM AUTHOR]

Mars experienced a dynamo process that generated a global magnetic field ~4.3 (or earlier) to 3.6 billion years ago (Ga). The cessation of this dynamo strongly affected Mars' history and is expected to be linked to thermochemical evolution of Mars' iron-rich liquid core, which is strongly influenced by its thermal conductivity. Here, we directly measured thermal conductivities of solid iron-sulfur alloys to pressures relevant to the Martian core and temperatures to 1023 Kelvin. Our results show that a Martian core with 16 weight % sulfur has a thermal conductivity of ~19 to 32 Watt meter-1 Kelvin-1 from its top to the center, much higher than previously inferred from electrical resistivity measurements. Our modeled thermal conductivity profile throughout the Martian deep-mantle and core indicates a ~4-to 6-fold discontinuity across the core-mantle boundary. The core's efficient cooling resulting from the depth-dependent, high conductivity diminishes thermal convection and forms thermal stratification, substantially contributing to cessation of Martian dynamo. [ABSTRACT FROM AUTHOR]

CTGS crystals are widely used in the field of high-temperature piezoelectricity because of their excellent piezoelectric properties. In this paper, the Ca2+ lattice of CTGS crystals is replaced by Sr2+ with a larger radius to improve their piezoelectric properties. (Sr0.2Ca0.8)3TaGa3Si2O14 and Ca3TaGa3Si2O14 single crystals with a diameter of 25 mm were grown using the vertical Bridgman method. The full width at half maximum (FWHM) of X-ray rocking curves of SCTGS and CTGS crystals are 57.6′′ and 22.3′′, respectively. It was found that the thermal properties of SCTGS crystals, such as specific heat, thermal diffusion and thermal conduction, are slightly lower than those of CTGS crystals. At room temperature, the dielectric permittivity ε T11 increased from 18.59 to 18.78, and the piezoelectric coefficient d11 also increased from 4.22 pC N−1 to 4.54 pC N−1. The electrical resistivities of the X-cut plates of SCTGS and CTGS crystals are approximately 3.78 × 107 Ω cm and 2.40 × 107 Ω cm at 800 °C, respectively. Therefore, SCTGS will be a promising candidate piezoelectric material in the field of high-temperature sensing. [ABSTRACT FROM AUTHOR]

The structural connectivity and kinematic relationship between the Altyn Tagh sinistral strike‐slip fault (ATF) and Qilian Shan fold‐and‐thrust belt along the north Tibetan margin east of 96°E is an important question for tectonicists interested in the evolving active deformation field of Central Asia and associated earthquake hazards of China's Hexi Corridor region. New results from a detailed 130‐km‐long N‐S magnetotelluric (MT) survey from the Qilian Shan to Beishan elucidates the locations and down‐dip orientations of major faults. Importantly, the results indicate that the Heishan‐Jinta'Nanshan fault system roots steeply into the lower crust, is unconnected to the Qilian Shan thrust wedge, and has reactivated the margin of the North China Craton and an older, regional ductile shear belt. The structurally linked ATF‐Heishan‐Jinta'Nanshan system defines a fundamental kinematic boundary in central Asia between the NE directed Qilian Shan thrust belt to the south and the eastwardly extruding Beishan‐Alxa Block to the north. Plain Language Summary: In this study, we present results of a comprehensive electrical resistivity survey conducted in the western Hexi Corridor region of China. The survey reveals significant sub‐surface faults and crustal boundaries, providing insights into the crustal structure between northernmost Tibet (Qilian Shan) and the Beishan. We document how the strike‐slip crustal boundary known as the Altyn Tagh Fault (ATF)‐Heishan‐Jinta'Nanshan system is steep and spatially unconnected to the Qilian Shan east of 98°E. It separates crustal blocks with contrasting motion histories; the southern block experiences compressional deformation, whereas the northern block accommodates extensional and transtensional deformation. Furthermore, the northeast trending ATF bends and converges into the more east‐west‐oriented Heishan‐Jinta'Nanshan system. We propose that this is a result of the Heishan‐Jinta'Nanshan system reactivating an older ductile shear belt and a mechanically weak boundary along the northwestern margin of the Precambrian North China Craton. Our study confirms the significance of inherited crustal structures in localizing continental interior reactivation and associated earthquake hazards. Key Points: A new detailed 3D resistivity model from Northern Tibet to the Southern Beishan clarifies the crustal structure in the NW Hexi CorridorThe Heishan fault system penetrates steeply to the lower crust and is unconnected to the Qilian Shan thrust wedgeCrustal thickening and mountain uplift in Qilian Shan is kinematically separated from eastward Beishan‐Alxa Block extrusion further north [ABSTRACT FROM AUTHOR]

We combined datasets from multiple research projects and remote sensing technologies to evaluate conservation conditions at La Fortaleza de Kuelap, a pre-Hispanic site in Peru that suffered significant damage under heavy seasonal rains in April 2022. To identify the causes of the collapse and where the monument is at further risk, we modeled surface hydrology using a DTM derived from drone LiDAR data, reconstructed a history of collapses, and calculated the volume of the most recent by fusing terrestrial LiDAR and photogrammetric datasets. In addition, we examined subsurface water accumulation with electrical resistivity, reconstructed the stratification of the monument with seismic refraction, and analyzed vegetation loss and ground moisture accumulation using satellite imagery. Our results point to rainwater infiltration as the most significant source of risk for La Fortaleza's perimeter walls. Combined with other adverse natural conditions and contemporary conservation interventions, this led to the 2022 collapse. Specialists need to consider these factors when tasked with conserving monuments located in comparable high-altitude perhumid environments. This integration of analytical results demonstrates how multi-scalar and multi-instrumental approaches provide comprehensive and timely assessments of conservation needs. [ABSTRACT FROM AUTHOR]

In this study, a series of FeCoNiAlSix (x = 0, 0.2, 0.4, and 0.6) high-entropy alloys (HEAs) were prepared by mechanical alloying and spark plasma sintering. The effects of Si alloying on the structural, thermal expansion, and magnetic properties of HEAs were investigated. The X-ray diffraction and microscopic results reveal that the crystal structure changes from FCC + BCC to single BCC phase with increasing Si content. By increasing Si content, the coefficient of thermal expansion decreases, especially at high temperatures, indicating that Si has a greater effect on improving the dimensional stability. In addition, the developed HEAs exhibit good saturation magnetization ~ 86.23 emu/g, low coercivity ~ 18.4 Oe, and high electrical resistivity ~ 84 µΩ.cm, indicating the present HEA can be used in soft magnetic applications. Furthermore, the hardness of HEAs increased from 510 ± 10 to 730 ± 10 HV with an increasing Si content due to formation of stable BCC phase. The present study demonstrates that alloying of Si facilitates a balance between desirable physical and mechanical properties. [ABSTRACT FROM AUTHOR]

Geophysical methods are widely used as noninvasive tools for archaeological prospection. In a first step is usually applied basic prospection of vast areas, when data are evaluated only in qualitative way. Sometimes is performed second step, during which take place more detailed multidimensional or combined surveys in order to image archeological monuments complexly, allowing quantitative interpretation. Hence, we used a unique and novel combination of multidimensional electrical resistivity tomography (ERT) on the Early Middle Ages stronghold fortifications at Vinoř (Czechia) to achieve such interpretation. The joint results of 2D/3D/4D (time-lapse) surveys allowed us to precisely characterize individual construction components of the fortifications, including a ditch and rampart enhanced by a front wall with a berm. The ERT results recovered the fortification dimensions and the volume of building material used. The surveyed fortification section was verified by excavations directly after the ERT measurements. A comparison of the excavated section with geophysics proved that ERT was able to infer all the important fortification characteristics. In addition, illustrative picture of the resistivity manifestations of the basic components of this very typical fortification construction were obtained. The results show that multidimensional ERT provide access to quantitative interpretation allowing to explain archaeological structures behind investigated anomalies. In result, sites containing cultural heritage can be leaved intact, excavations can be substituted in surprisingly large extent, while unprecedented amount of archaeological information is still retrieved. [ABSTRACT FROM AUTHOR]

Graphite is considered to be one of Europe's most critical minerals. It is necessary for the transition from hydrocarbon fuel to electricity due to its use in batteries that power electronic devices and electric transport. In the past, high-quality exposed graphite was found in Norway without today's advanced geophysical and geological methods. Norway is a key destination in Europe for graphite production. With an increasing demand for graphite, there have been efforts to systematically survey the country using modern geophysical and geological methods to find hidden graphite deposits. Among the various geophysical survey methods, electrical and electromagnetic (EM) methods are the first choice for the exploration of graphite due to the material's high electrical conductivity. Airborne surveys are often used to cover a large area for a regional reconnaissance survey to locate the sites with potential mineral deposits before performing ground geophysical and geological surveys. Therefore, frequency-domain helicopter EM (HEM) and airborne magnetic surveys were performed in Northern Norway to locate interesting anomalies which were followed by ground surveys such as electrical resistivity tomography (ERT), charged-potential (CP), self-potential (SP), ground EM, and geological surveys. Some locations were also investigated with drilling and petrophysical core-sample analysis. In this paper, we present helicopter EM and magnetic data, 3D inversion of HEM data, and a successful ground follow-up survey result from the Vesterålen district in Northern Norway. The HEM survey identified previously known and new graphite occurrences, both partially exposed or buried, which were confirmed using ground surveys, drilling, and laboratory analysis of the samples. [ABSTRACT FROM AUTHOR]