Changes In Electrical Conductivity Research Articles

Variations in Cold Resistance and Contents of Bioactive Compounds among Dendrobium officinale Kimura et Migo Strains

Dendrobium officinale is a valuable traditional Chinese herbal plant that is both medicinal and edible. However, the yield of wild Dendrobium officinale is limited. Adverse stress affects the growth, development, and yield of plants, among which low temperature is the primary limiting factor for introducing Dendrobium officinale to high-latitude areas and expanding the planting area. Therefore, this study aims to explore the variations in growth ability, cold resistance, and contents of bioactive compounds among different Dendrobium officinale strains. Four strains of Dendrobium officinale were selected as experimental materials and were subjected to low-temperature stress (4 °C). The agronomic traits, physiological indices, as well as the expressions of cold resistance-related genes (HSP70, DcPP2C5, DoCDPK1, and DoCDPK6) in the roots and leaves of Dendrobium officinale, were determined. The contents of bioactive compounds, including polysaccharides, flavonoids, and phenols were also measured. Compared with the other strains, Xianju had the highest seed germination and transplantation-related survival rates. Under low-temperature stress, Xianju exhibited the strongest cold resistance ability, as revealed by the changes in water contents, chlorophyll levels, electrical conductivities, enzyme activities, and expressions of the cold resistance-related genes. Additionally, the polysaccharide content of Xianju increased the most, while the stem flavonoid and leaf phenol contents were elevated in all four strains under cold treatment. Therefore, selecting excellent performing strains is expected to expand the planting area, improve the yield, and increase the economic benefits of Dendrobium officinale in high latitude areas with lower temperatures.

Gas‐Induced Electrical and Magnetic Modulation of Two‐Dimensional Conductive Metal–Organic Framework

AbstractControlled modulation of electronic and magnetic properties in stimuli‐responsive materials provides valuable insights for the design of magnetoelectric or multiferroic devices. This paper demonstrates the modulation of electrical and magnetic properties of a semiconductive, paramagnetic metal−organic framework (MOF) Cu3(C6O6)2 with small gaseous molecules, NH3, H2S, and NO. This study merges chemiresistive and magnetic tests to reveal that the MOF undergoes simultaneous changes in electrical conductance and magnetization that are uniquely modulated by each gas. The features of response, including direction, magnitude, and kinetics, are modulated by the physicochemical properties of the gaseous molecules. This study advances the design of multifunctional materials capable of undergoing simultaneous changes in electrical and magnetic properties in response to chemical stimuli.

Soil quality evaluation for irrigated agroecological zones of Punjab, Pakistan: The Luenberger indicator approach

AbstractThis article describes the construction of the Luenberger soil quality indicator (SQI) using data on crop yield, non‐soil inputs, and soil profile from three irrigated agroecological zones of Punjab, Pakistan, namely, rice–wheat, maize–wheat–mix, and cotton–mix zones. Plot level data are used to construct a soil quality indicator by estimating directional distance functions within a data envelopment analysis (DEA) framework. We find that the SQI and crop yield relationships exhibit diminishing returns to improving soil quality levels. Using the constructed SQI values, we estimate linear regression models to generate weights that could be used directly to aggregate individual soil attributes into soil quality indicators without the necessity of fitting a frontier to the crop production data. For wheat and rice production, we find that SQI is most sensitive to changes in soil electrical conductivity (EC) and potassium (K). The SQI has direct relevance for site‐specific decision‐making problems where policymakers need to price land resources and conservation services to achieve agricultural and environmental goals.

Dual‑carbon confined Sb2Se3 nanorods for potassium ion batteries anode with improved capacity and cycling stability

Sb2Se3 is regarded as a promising conversion-alloying type anode material for potassium ion batteries (PIBs) owing to its high theoretical specific capacity. However, the low electric conductivity and large volume change during the charge/discharge process hinder its practical applications. Herein, we proposed a novel ‘dual carbon coating’ strategy to construct carbon confined Sb2Se3 nanorods for high performance PIBs anode. Owing to the enhanced electric conductivity resulted from the inner carbon and the strengthened mechanical stability from the outer graphene layer, the confined Sb2Se3 exhibit outstanding electrochemical potassium ion storage performances with a specific capacity of 482.1 mAh g−1 after 50 cycles at a current density of 0.1 A g−1. Even at a high current density of 1 A g−1 after 500 cycles, it still maintains a specific capacity of 283.7 mAh g−1. These results outperform the pure Sb2Se3 and those traditional ‘single carbon’ coated Sb2Se3 from both specific capacity and cycling stability. This ‘dual carbon coating’ method could also be applied to other conversion or alloying type anode materials of PIBs with high theoretical capacities and large volume variation during the repeated charge/discharge process.

EXPERIMENTAL STUDIES OF ELECTRIC CONDUCTIVITY DISTRIBUTION ALONG THE HEIGHT OF THE FLUIDIZED BED

This work is focused on the experimental research into the electrical conductivity of a fluidized bed with graphite particles. The aim of the study is to determine the change in electrical conductivity along the height of the fluidized bed. The study was carried out on a chamber-type unit with a working space diameter 110 mm at a fluidization index 2-3. As a result of the experimental research, during heating in electrothermal fluidized bed, the uneven distribution of electrical resistance along the bed height was confirmed for the first time. The resistivity value increases 3-5 times with the depth of immersion into the bed from its surface. The unevenness of the resistivity along the height of the bed decreases with increasing temperature. The difference in power distribution due to uneven electrical resistance along the bed height can lead to a temperature difference of several tens of degrees.

In situ Preparation of SiOx/Carbon Nanotube Composite Films with Excellent Mechanical and Electrochemical Properties as an Anode Material for Lithium‐Ion Batteries

Silicon monoxide (SiOx) has become one of the most promising anode materials for next‐generation lithium‐ion batteries (LIBs) due to its high theoretical capacity. However, the inherent low electrical conductivity and large volume change during lithiation/delithiation processes hinder its practical applications. Here, a novel and facile strategy is designed to prepare SiOx/carbon nanotube (CNT) composite films in one step by using a method involving floating catalytic chemical vapor deposition (FCCVD). That is, SiOx particles and CNTs form at high temperature and winded directly on a drum to give rise to a film in an open air environment. The composite film is made up of a 3D CNT network with SiOx particles uniformly embedded. The as‐prepared composite film not only has a tensile strength of 78 MPa and elongation at break of 52%, but also exhibits a high specific capacity of 966.4 mA h g−1 after 120 cycles at the current density of 0.1 A g−1 and a good rate capacity of 448.7 mA h g−1 at the current density of 2 A g−1 when used as an anode material for LIBs. The results from the in‐situ preparation and resultant composite suggest a new route for developing high‐performance anode materials for LIBs.

Chronic Ethanol Decreases the Left Ventricular Cardiac Performance

Introduction: Spaced fiber bundles, less evident cell striations, deposition of collagen fiber bundles, and increased presence of fibroblasts in the cardiac tissue of rats that voluntarily and chronically ingested ethanol were observed by our research group. In addition, we observed increased proliferation and cell death of cardiomyocytes. To find out whether these changes lead to impaired heart functionality, some clinical tests were performed. Aim: to investigate whether chronic ethanol decreases the left ventricular performance assessed by exercise testing, electrocardiogram, and echocardiogram of male and female UChB strain rats. Material and methods: ten adult males and ten adult females, Wistar strain rats, named UChB (University of Chile), spontaneous high ethanol drinkers (consumption greater than 2 g ethanol / Kg body weight/day), and ten male UChB rats and ten adults female UChB rats, not exposed to ethanol, UChBC rats (controls) were used. Cardiac performance was evaluated by the stress test, electrocardiogram, and echocardiogram. Results: Exposed females showed ventricular morphological changes in the heart. The exposed females and males had the highest heart relative weight with females being larger than males. The exposed females showed altered electrocardiogram and echocardiogram. Conclusion: Chronic ethanol decreases the left ventricular cardiac performance in rats. Females are more sensitive to changes in cardiac electrical conduction.

Tunable High-Performance Electromagnetic Interference Shielding of VO2 Nanowires-Based Composite.

The unique metal-insulator transition of VO2 is very suitable for dynamic electromagnetic (EM) regulation materials due to its sharp change in electrical conductivity. Here, we have developed an off/on switchable electromagnetic interference (EMI) shielding composite by interconnecting VO2 nanowires (NWs) in poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) to form conductive networks, resulting in outstanding performance at the X and Ku bands with maximum change values of 44.8 and 59.4 dB, respectively. The unique insulator-to-metal transition (IMT) of VO2 NWs has dominated the variation of polarization loss (εp″) and conductivity loss (εσ″) for the composites, which is the mechanism of EMI shielding switching between off and on states. Furthermore, the composite exhibits good cycling stability of the off/on switchable EMI shielding performance and has excellent mechanical properties, especially with 200 times abrasion resistance without obvious weight loss. This study provides a unique approach for dynamic switching of EM response with the potential to construct practical intelligent EM response systems for next-generation smart electromagnetic devices in various scenarios.

Gas-Induced Electrical and Magnetic Modulation of Two-Dimensional Conductive Metal-Organic Framework.

Controlled modulation of electronic and magnetic properties in stimuli-responsive materials provides valuable insights for the design of magnetoelectric or multiferroic devices. This paper demonstrates the modulation of electrical and magnetic properties of a semiconductive, paramagnetic metal-organic framework Cu3(C6O6)2 with small gaseous molecules, NH3, H2S, and NO. This study merges chemiresistive and magnetic tests to reveal that the MOF undergoes simultaneous changes in electrical conductance and magnetization that are uniquely modulated by each gas. The features of response, including direction, magnitude, and kinetics, are modulated by the physicochemical properties of the gaseous molecules. This study advances the design of multifunctional materials capable of undergoing simultaneous changes in electrical and magnetic properties in response to chemical stimuli.

Adsorption and gas sensitive behavior of Co2+ doped TiO2(101) crystal planes

Density functional theory (DFT) and Electrochemical Impedance Spectroscopy (EIS) were used to study the molecular adsorption behavior of the Co2+ doped TiO2(101) crystal plane, and the ethanol molecular gas sensitivity test was performed. Theoretical models indicate that doping leads to oxygen defects on the crystal plane and further chemisorption of two oxygen molecules, resulting in reduced electrical conductivity and improved oxygen storage capacity on the crystal plane. Ethanol molecules do not compete with N2, O2, and H2O molecules on doped crystal planes because of their different adsorption active sites, which means that the response time of gas-sensitive detection of ethanol molecules is short and is not interfered with the air molecules in the test environment. These results were confirmed by EIS and gas sensitivity experiments. The change of electrical conductivity after the adsorption of molecules on the crystal plane was confirmed by EIS. The enhanced oxygen storage capacity of the doped crystal plane was confirmed by the expansion of the linear response range of gas-sensitive detection from 20-100 ppm before doping to 20–1200 ppm. This provides a scientific basis for effectively shortening the gas-sensitive response time, increasing the concentration range, improving the oxygen-carrying capacity, and enhancing the catalytic and gas-sensitive properties of the material.

Split-ring resonator with interdigital Split electrodes as detector for liquid and ion chromatography

The analysis of food and drugs as well as the monitoring of chemical processes and bioreactors by high-performance liquid chromatography and ion chromatography requires universal, cost-effective, and sensitive detectors. Therefore, this work presents a split-ring resonator that detects changes in the electrical and dielectric properties of the eluate from liquid chromatography or ion chromatography by monitoring the amplitude of the transmitted signal using an envelope detector. The used split-ring resonator consists of a simple printed circuit board featuring two microstrip lines. One is formed to a ring with interdigital split electrodes. The interdigital split electrodes forming the sensitive area significantly enhance the sensitivity to changes in relative permittivity, dielectric losses and electrical conductivity of the eluate In addition, the split-ring resonator is a small, inexpensive and easy-to-use detector that uses several dielectric parameters simultaneously for the measurement. Furthermore, the split-ring resonator measures these parameters at a significantly lower frequency than optical detectors and therefore measures different changes in frequency-dependent permittivity. For demonstrating feasibility of a split-ring resonator as a detector for high-performance liquid chromatography and ion chromatography, various anion and cation standards, basic and acidic amino acids, sugars, as well as sugar alcohols were separated and detected. A conductivity detector for ion chromatography and a refractive index detector for high-performance liquid chromatography were used as reference detectors.

Визначення величини енергетичної невпорядкованості в аморфних оксидних напівпровідниках

The amorphous material films are resistant to high-energy irradiation. Therefore, devices built using the properties of these materials can work in conditions of increased radiation much longer than devices using the properties of crystals. An important characteristic of these materials is their degree of disorder. To determine this characteristic, a model of random fluctuations of the local edge of the conduction band is considered for the theoretical study of magnetoconductivity in amorphous oxide semiconductors. The effective medium approximation is used. An approach to determining the amount of energy disorder based on experimental measurement of changes in longitudinal and transverse electrical conductivity in a magnetic field is proposed.

Pomegranate-like heterostructured SnS2/CoS2 particles encapsulated in S, N dual-doped carbon framework enabling high-rate and durable sodium ion storage

As a promising anode material for sodium-ion batteries, SnS2 has attracted increasing attention owing to its high theoretical capacity and abundant reserves. Unfortunately, the poor electrical conductivity and drastic volume changes lead to unsatisfactory cycling and rate performance, largely limiting its practical application. Herein, we report a pomegranate-like composite of heterostructured SnS2/CoS2 spheres encapsulated in S, N dual-doped carbon framework (SnS2/CoS2@SNC) obtained by a simple ion adsorption, in situ polymerization coating of polydopamine and subsequent calcination strategy. The integration of CoS2 with SnS2 particles with abundant interfaces can provide rich redox chemistry and accelerated ion diffusion kinetics, while the coated S, N dual-doped carbon shell enables good electrical conductivity and reinforced structural integrity as well by accommodating the volume changes and inhibiting the collapse/pulverization of active materials during the cycling process. As a consequence, the pomegranate-like heterostructured SnS2/CoS2@SNC anode exhibited a higher capacity (743 mAh g−1 at 1 A g−1), excellent rate capability (213 mAh g−1 at 50 A g−1) and outstanding cycling stability (560 mAh g−1 at 5 A g−1 after 1000 cycles), showing the application feasibility of this anode material for developing high-rate and durable SIBs.

Heat activated VO2 (R) cathodes for high-performance aqueous zinc ion batteries

We introduce a novel approach for design and production of vanadium dioxide (VO2) cathodes activated by heat, specifically tailored for use in aqueous zinc-ion batteries (ZIBs). Our cathodes exhibit distinctive metal-insulator transition (MIT) characterized by the shift between monoclinic (M) and tetragonal rutile (R) phases. The employment of an aqueous electrolyte in ZIBs enables successful operation of VO2 cathodes, showcasing phase transition and enhanced electrochemical performance above a readily attainable temperature of approximately 68 °C. The MIT feature enhances the charge transfer properties at electrode-electrolyte interfaces, resulting in notable improvements in specific capacity and energy densities. Fabricated VO2(M) cathodes underwent heat-triggered transformation to VO2(R), resulting in a remarkable increase (400 %) in capacity. At 0.1 A g−1, VO2(R) cathodes show specific capacity of 354.6 mAh g−1, yielding an impressive energy density of 461.0 Wh kg−1 for aqueous ZIBs. This exceptional performance can be attributed to abrupt change in electrical conductivity upon thermal activation of MIT. This work underscores pivotal role of thermally activated MIT in finely tuning electrochemical performance of energy storage systems, prospecting a promising avenue for further advancements.

Effects of returning paddy field to wetland on composition and stability of soil aggregates in the Yellow River Delta.

The composition and stability of soil aggregates are important indicators for measuring soil quality, which would be affected by land use changes. Taking wetlands with different returning years (2 and 15 years) in the Yellow River Delta as the research object, paddy fields and natural wetlands as control, we analyzed the changes in soil physicochemical properties and soil aggregate composition. The results showed that soil water content, total organic carbon, dissolved organic carbon and total phosphorus of the returning soil (0-40 cm) showed an overall increasing trend with returning period, while soil pH and bulk density was in adverse. There was no significant change in clay content, electrical conductivity, and total nitrogen content. The contents of macro-aggregates and micro-aggregates showed overall increasing and decreasing trend with returning period, respectively. The stability of aggregates in the topsoil (0-10 cm) increased with returning years. Geometric mean diameter and mean weight diameter increased by 8.9% and 40.4% in the 15th year of returning, respectively, while the mass proportion of >2.5 mm fraction decreased by 10.5%. There was no effect of returning on aggregates in subsoil (10-40 cm). Our results indicated that returning paddy field to wetland in the Yellow River Delta would play a positive role in improving soil structure and aggregate stability.

Enhancement of riboflavin-mediated photodynamic inactivation against Salmonella on tuna fillets coupled with slightly basic electrolyzed water

This study aimed to develop an efficient PDI system to kill Salmonella in solution or on tuna fillets under 455 nm blue light-emitting diodes (LED) irradiation, by selecting slightly basic electrolyzed water (SBEW) as the solvent. Results showed that the solvent of SBEW increased the solubility of riboflavin, and notably strengthened the production of ROS compared to normal saline solution. On this basis, the riboflavin-mediated PDI coupled with SBEW enhanced the inactivation of Salmonella, supported by that the viability of Salmonella was significantly (P < 0.05) inactivated by 5.02 Log10 CFU/mL with 9.36 J/cm2 irradiation and 80 μM riboflavin, and no viable cells were detected when the irradiation dose was increased to 12.48 J/cm2. The action mechanisms showed that this novel PDI damaged the cell membrane causing the leakage of cellular contents, degraded the genomic DNA and enhanced the lipid peroxidation in Salmonella. In addition, the PDI system efficiently killed >4.0 Log10 CFU/g of Salmonella on tuna fillets with 120 μM riboflavin and 18.72 J/cm2 irradiation. Furthermore, the PDI system decelerated the proliferation of Salmonella, the changes of electrical conductivity, pH and color, and lipid oxidation in tuna fillets during the storage. This study provides a promising PDI system to control food pathogen contamination and preserve the storage quality of seafood.

Production and properties of electrically conductive polymer composites reinforced with cotton threads

AbstractThe problem of strength loss in electrically conductive composites made with dispersed fillers in the polymer binder is solved by spraying an aerosol of graphite on a textile material with a 3D weave of threads, or on knitwear of fibers with various structure and chemical composition. The loose microstructure of cotton fibers and the developed surface of elastic filaments made of synthetic polymers retain colloidal graphite particles in a layered composite during cyclic deformation. The electrical conductivity of knitwear with graphite changes during stretching due to the reversible displacement of graphite particles, first during straightening and then during stretching of elastic threads. The 130 ± 5 strain sensitivity GF and 12,000 ± 95 кPa−1 stress sensitivity QF of the composites presented in this paper exceed the corresponding parameters of known electrically conductive composites. The combination of a significant change in electrical conductivity with the elasticity of the developed knitwear‐based composite is important for the use in load cells, smart clothes, medical devices, and robotics.

Photothermal synergistic high-sensitivity self-driven vertical asymmetric Te/Bi2Te3/In2O3 heterojunction near-infrared imaging photodetector

Infrared detection and imaging devices have great potential in the fields of defense and security, medical monitoring, and food safety. As a novel method, photothermal assistants can expand the absorption in the case of low-angle dependence, which is one of the key factors in improving the performance of infrared detectors. Photo-heating accelerates the transfer of carrier, inducing a change in electrical conductance and exciting “hot” electrons promote a photoelectric response and extend the response photon energies well below the semiconductor band edge. However, photodetectors require cooling to prevent overheating and reduce thermal noise, thereby improving photoelectric detection. Therefore, it remains a formidable challenge to design a suitable heterojunction photodetector that can synergistically utilize optical and thermal energy. Here, a unique asymmetric Te/Bi2Te3/In2O3 heterojunction structure is designed by a simple physical deposition method, and a photothermal synergistic infrared detector is successfully fabricated. The Te/Bi2Te3/In2O3 heterojunction exhibits excellent self-driven photo-detection performance in the near-infrared wavelength bands of 850, 980, and 1050 nm, especially under prolonged laser irradiation at 850 nm. Under prolonged laser irradiation at 850 nm (0 bias), the heterojunction exhibits ultra-fast (response time < 55 ms), ultra-sensitive, and stable detection behavior, with a response rate as high as 0.4195 mA/W (Ri of 0.4724 mA/W, after 1,000 cycles), Iph/Idark is 281.55, and the detectivity as high as 4.296 × 109 Jones. A high-resolution current image was obtained under 980 nm illumination at room temperature without bias. Such excellent optoelectronic properties make the heterojunctions of the asymmetric Te/Bi2Te3/In2O3 heterojunction a potential candidate for future infrared detection and imaging.

Spatial distribution characteristics and degradation mechanism of microorganisms in n-hexadecane contaminated vadose zone

The damage caused by petroleum hydrocarbon pollution to soil and groundwater environment is becoming increasingly significant. The vadose zone is the only way for petroleum hydrocarbon pollutants to leak from surface into groundwater. The spatial distribution characteristics of indigenous microorganisms in vadose zone, considering presence of capillary zones, have rarely been reported. To explore the spatial distribution characteristics of indigenous microorganisms in vadose zone contaminated by petroleum hydrocarbons, a one-dimensional column migration experiment was conducted using n-hexadecane as characteristic pollutant. Soil samples were collected periodically from different heights during experiment. Corresponding environmental factors were monitored online. The microbial community structure and spatial distribution characteristics of the cumulative relative abundance were systematically analyzed using 16S rRNA sequencing. In addition, the microbial degradation mechanism of n-hexadecane was analyzed using metabolomics. The results showed that presence of capillary zone had a strong retarding effect on n-hexadecane infiltration. Leaked pollutants were mainly concentrated in areas with strong capillary action. Infiltration and displacement of NAPL-phase pollutants were major driving force for change in moisture content (θ) and electric conductivity (EC) in vadose zone. The degradation by microorganisms results in a downward trend in potential of hydrogen (pH) and oxidation-reduction potential (ORP). Five petroleum hydrocarbon-degrading bacterial phyla and 11 degradable straight-chain alkane bacterial genera were detected. Microbial degradation was strong in the area near edge of capillary zone and locations of pollutant accumulation. Mainly Sphingomonas and Nocardioides bacteria were involved in microbial degradation of n-hexadecane. Single-end oxidation involved microbial degradation of n-hexadecane (C16H34). The oxygen consumed, hexadecanoic acid (C16H32O2) produced during this process, and release of hydrogen ions (H+) were the driving factors for reduction of ORP and pH. The vadose zone in this study considered presence of capillary zone, which was more in line with actual contaminated site conditions compared with previous studies. This study systematically elucidated vertical distribution characteristics of petroleum hydrocarbon pollutants and spatiotemporal variation characteristics of indigenous microorganisms in vadose zone considered presence of capillary zone. In addition, the n-hexadecane degradation mechanism was elucidated using metabolomics. This study provides theoretical support for development of natural attenuation remediation measures for petroleum-hydrocarbon-contaminated soil and groundwater.

Investigating arc and molten metal transport phenomena in gas metal arc welding with Ar–CO2 gas mixtures using a numerical method

This paper presents a numerical investigation of the transient transport phenomena of the arc and molten metal during gas metal arc welding (GMAW) using shielding gas mixtures ranging from 100% Ar + 0% CO2 to 80% Ar + 20% CO2. The thermophysical parameters of the Ar–CO2 mixtures, considering the presence of metal vapor, were calculated as a function for a temperature range of 1000–30 000 K. The influence of metal vapor content and CO2 proportion on the thermophysical properties of the mixed gas was discussed in detail. As the CO2 content increased from 0 to 20%, the shape of the arc changed from a bell to a cone due to the increase in mass density, specific heat, and thermal conductivity. The maximum arc temperature and velocity decreased with increasing CO2 content, resulting in larger droplets and a lower droplet transfer frequency. Although the change in electrical conductivity did not affect the arc shape, it did influence the arc temperature by altering the distribution of current density. Experiments of droplet transfer and arc behavior were carried out, and the results showed that the simulated droplet size, transfer frequency, and arc temperature distribution agreed well with the experimental values. These findings could serve as a theoretical tool for better understanding the underlying physical mechanisms of the GMAW process using different shielding gases, ultimately aiming to achieve high weld quality.