Variation Of Conductivity Research Articles

Eukaryotic plankton community and assembly processes in a large-scale water diversion project in China

The Middle Route of the South to North Water Diversion Project (MRP) and its water source, the Danjiangkou Reservoir (DJK), play a pivotal role in mitigating the chronic water scarcity challenges faced by northern China. Eukaryotic plankton are widespread in aquatic ecosystems, which are crucial for the water quality stability of DJK and MRP, yet comparative studies on their contemporaneous dynamics and assembly processes are scarce. In this study, amplicon sequencing was used to investigate the eukaryotic plankton communities. The results revealed that the similarity in community composition of DJK is significantly higher than that of MRP, exhibiting distance-decay patterns. Environmental heterogeneity exhibits significant differences between DJK and MRP, and it significantly influences community composition and alpha diversity. Additionally, the assembly processes of eukaryotic plankton in both DJK and MRP are predominantly influenced by stochastic processes. However, in comparison to DJK, deterministic processes have a more pronounced impact on MRP, accounting for 39.29% and 1.82%, respectively. The variations in total nitrogen (TN), chlorophy IIa (Chl.a), and conductivity (Spc) have led to a transition in the assembly of eukaryotic phytoplankton communities in MRP from a stochastic process to a deterministic process. This study extends insights into the dynamics and assembly processes of eukaryotic plankton communities in the large, engineered drinking water diversion project and its water source, which is also useful for the management and regulation of the DJK and MRP.

A Stimulus‐Responsive Optoelectronic Skin From Photonic Crystal

AbstractIn nature, the ability to regulate and transmit color signals is fundamental to the adaptive survival of many organisms. A key aspect of this adaptability is the autonomous detection of chromatic changes in color‐displaying structures, facilitating precise color matching with environmental stimuli. However, conventional mechanochromic materials rely on a single mechanical force feedback channel, lacking the ability to continuously monitor their color state in real‐time. In this work, a novel approach is presented that integrates ZnS@SiO2 photonic crystals and LiCl into a TEMPO‐Oxidized cellulose nanofibers‐polyacrylamide hydrogel matrix (PAM‐TOCNF hydrogel), which successfully endow conductivity variation into this mechanochromic hydrogel. This system mimics the chameleonic mechanism by coupling mechanical force with ion conduction to achieve responsive color changes and real‐time color process monitoring. These findings establish a new paradigm for optoelectronic systems with stimulus‐responsive capabilities, paving the way for future advancements in bio‐inspired, adaptive technologies.

Impacts of Stress‐dependent Hydraulic Properties on Hillslope‐Scale Groundwater Flow

AbstractGroundwater flow at the hillslope scale is controlled by hydraulic properties and topography. Geological media are inherently heterogeneous, with properties depending on both lithology and external factors such as weathering, erosion, and tectonic activity. The effects of stress‐dependent variations in porosity and hydraulic conductivity on groundwater flow and residence times remain unexplored. Using process‐based hillslope models, we demonstrate how external lateral stresses cause significant variations in stress and strain, particularly on slopes steeper than 30%. These stresses reorganize porosity and hydraulic conductivity, with compressive regimes reducing these properties at valley bottoms and tensional regimes elevating values at crests. This redistribution of porosity and hydraulic conductivity leads to a channeling of groundwater flow near the surface. Channeling increases discharge rates in the upper seepage zone and the proportion of rapid flows. Our results highlight geomechanical‐hydraulic property relationships as critical controls on critical zone processes in mountain settings.

Numerical Investigation of Dual Metal Hydride Bed Based Thermochemical Energy Storage System

Thermochemical energy storage system is known for good thermal stability and high energy storage density. Metal hydride based thermochemical energy storage systems are reported to store thermal energy at higher temperatures. In this analysis, NaMgH2F and Mg2NiH4 are used as high temperature and low-temperature metal hydrides. One kg of NaMgH2F is used as thermal energy storage media, while Mg2NiH4 is used as hydrogen storage media. The analysis includes the study of energy charging and discharging characteristics with heat transfer phenomenon in metal hydride with variation in thermal conductivity of high temperature metal hydride bed. With the increase in thermal conductivity of high temperature metal hydride bed, the heat transfer between heat transfer fluid and metal hydride bed during the energy charging and discharging process has improved. A marginal increase in thermal energy stored and discharged in/from the metal hydride bed system has been observed with an increase in the thermal conductivity of the metal hydride bed. Thermal energy stored in the MH beds for thermal conductivity of 0.5 W/m K, 0.75 W/m K, and 1 W/mK, are 270.88 kJ, 273.39 kJ, and 274.96 kJ, respectively. The energy desorbed from the system for thermal conductivity 0.5 W/mK, 0.75 W/mK, and 1 W/mK are observed as 251.25 kJ, 258.22 kJ, and 260.57 kJ, respectively. The three cases of thermal conductivity have reported an energy storage efficiency of 92.75%, 94.45%, and 94.77%, respectively.

Study on the change of the oil-paper insulation’s AC conductivity characteristics based on dielectric response in frequency domain

Oil-immersed power equipment (transformers and high voltage bushings) are key components of power systems. Oil-paper insulation has endured complex and harsh operating conditions when used as a primary insulation system, so it is essential to determine the insulation state of oil-paper insulation system to ensure a stable operation for the power grid. The oil-paper insulation’s conductivity behavior can effectively characterize the degree of insulation deterioration. However, the relationship between the alternating current (AC) and direct current (DC) conductivity behavior for oil-paper insulation systems is still unclear in current research, resulting in limitations in the traditional evaluation model’s application. Therefore, this paper uses oil-paper insulation materials under different aging to carry out relevant research about the changing features of the complex AC conductivity under different test temperature environments. The influence of oil-paper insulation aging, test temperature, and excitation frequency on the complex AC conductivity is verified. Considering the correlation between low-frequency AC conductivity and DC conductivity, the frequency range of AC conductivity is extended by means of frequency temperature and conductance double translation. The temperature dependence of the AC conductivity behavior is defined over a wide frequency test range. The relaxation polarization process dominated the AC conductivity variation law is obtained. The impact of experimental temperature and insulation aging on the cumulative characteristic parameters of AC ionic mobility is clarified. This study theoretically corrects the traditional calculation model for AC conductivity of oil-paper insulation. The bias in conductivity calculations caused by only considering a single relaxation polarization process is eliminated. The conductivity model that can characterize multiple relaxation polarization processes in the dielectric is established. This model provides theoretical support for the later assessment of oil-paper insulation state depending on conductance behavior.

Percolation theory-based KMC simulation for scaled Fe-FET based multi-bit computing-in-memory with temperature compensation strategy

In this letter, we investigate the impact of percolation transport mechanisms on ferroelectric field effect transistor (FeFET) multi-value storage with kinetic Monte-Carlo (KMC) simulation considering aspect ratio and temperature dependencies. It is found that the portion of the ferroelectric polarization, which dominates the threshold voltage shift of the FeFET, increases when aspect ratio of device decreases. Moreover, randomness of percolation path formation and variations of equivalent conductance can be suppressed, indicating mitigation of device-to-device variations and enhancement of separation of individual states. Besides, to further investigate an amorphous channel promising in multi-bit applications, disorder effects in channel contribute to intrinsic percolation transport, coupling with multi-domain dynamics in Fe-layer, are studied by the high temperature characterization. On this basis, the KMC scheme is further modified to predict multi-value distribution from 300 K to 400 K. To tackle such critical reliability issues induced inaccuracy for in-memory computing (CIM), an efficient write-verify scheme is proposed to mitigate state overlapping and provide in-depth insights for co-design of device reliability and multi-bit CIM performances.

Divergence of vessel diameter explains interspecific variation in hydraulic safety to salinity in the Sundarbans mangrove ecosystem

Abstract Despite their crucial role in providing ecosystem services and livelihood support in 124 countries, mangroves are facing challenges from warming, altered seasonal precipitation and sea level rise (SLR) in the face of climate change. Variation in intra‐ and interspecific hydraulic traits and related xylem anatomy may allow trees to adapt to changing environmental conditions, yet little is known about adaptive plasticity in mangroves. We examined (i) xylem and hydraulic trait variation across three (low, medium and high) salinity zones in three widespread mangrove species (Exocecaria agallocha, Xylocarpus moluccensis and Heritiera fomes) with distinct shade tolerance characteristics in the Bangladesh Sundarbans, (ii) associations of xylem and hydraulic traits, and (iii) habitat (regulator, resource and forest structure) effects on vessel diameter due to its strong influence on hydraulic conductivity variation. Although potential conductivity (KP) and leaf‐specific conductivity (KL) showed species‐specific variation, a notably greater conductivity was found in the low‐salinity zone (LSZ), which had lower vessel wall reinforcement (t/b)2. Xylem and hydraulic traits exhibited mostly strong phylogenetic signals, whereas pairwise relationships between traits were phylogenetically independent. The study species had distinct hydraulic characteristics, where vessel diameter (D) was strongly related to the variation in KP and KL. Furthermore, the study species exhibited a weak trade‐off between hydraulic efficiency and safety. A greater percentage of smaller vessel diameters in light‐demanding E. agallocha indicates greater hydraulic safety against cavitation under stressful conditions than in shade‐tolerant H. fomes, followed by X. moluccensis. Although species characteristics place broad bounds on xylem traits, the combined effects of salinity, nutrient availability and tree size modulate vessel diameter, which leads to hydraulic conductivity variation. The contrasting safety in terms of vessel diameter in mangroves suggests an important role in adaptation to salinity and species distribution. The results also provide insight into salinity‐induced growth reduction and mortality in mangroves. Read the free Plain Language Summary for this article on the Journal blog.

Effects of Bottom Channel Coverage Ratio on Leakage Current and Static Power Consumption of Vertically Stacked GAA Si NS FETs

Abstract The performance of vertically stacked gate-all-around silicon nanosheet (GAA Si NS) field-effect transistors (FETs) is significantly impacted by the non-ideal characteristics of the bottom channel, primarily due to etching process limitations. These issues lead to variations in the coverage ratio of the bottom channel, which impacts key device characteristics like leakage current and static power consumption. In this study, we used experimentally calibrated 3-D device simulations to analyze the effects of varying bottom channel coverage ratios from 60% to 100% on the GAA Si NS n-/p-type FETs for sub-2-nm technology nodes. Our results reveal an inverse relationship between the coverage ratio and leakage current and static power consumption. Notably, n-/p-type devices at 60% bottom channel coverage ratio exhibiting leakage currents 75.6 and 102.7 times higher than those with 100% bottom channel coverage ratio. This increase is linked to substantial variations in the off-state conduction (18.5%, 75 meV for n-type FETs) and valance (15.3%, 57 meV for p-type FETs) band energies. An 80% bottom channel coverage ratio proves to be an effective compromise, reducing parasitic leakage while addressing manufacturing feasibility. However, achieving a 100% bottom channel coverage ratio remains a critical challenge, highlighting the need for further research on fabrication optimization.

Proton Conductivity Variations in Hydrogen-Bonded Crystals Induced by Cyclic Steric Hindrance

Proton Conductivity Variations in Hydrogen-Bonded Crystals Induced by Cyclic Steric Hindrance

Correlation Study of Auroral Currents with External Parameters During 10–12 October 2024 Superstorm

This study investigated the correlations between field-aligned currents (FACs), polar electrojets (PEJs), and external solar and geomagnetic activity parameters during the intense geomagnetic storm that occurred from 10 to 12 October 2024. Notably, the merging electric field (Em) had a greater impact on FACs and PEJs compared to the May 2024 storm, while the influence of solar wind pressure (Pd) was equally important in both storms. The peak FAC densities in the northern dawn (southern dusk) and nighttime sectors correlate strongly with Em, whereas Pd dominates in the northern dusk (southern dawn) and daytime sectors. For PEJs, Em correlates strongly with current densities in the northern dawn–dusk and southern nighttime sectors, while Pd is the primary correlated parameter on the dayside. FAC (PEJ) latitudes are most strongly influenced by Em (Pd or Dst) on the dawnside–duskside. Additionally, FACs and PEJs are mostly more intense on the dawnside than on the duskside and extend to lower latitudes at dusk than at dawn. Analysis of the May and October 2024 storms reveals that FACs in the summer hemisphere are generally stronger and situated at more poleward latitudes than those in the winter hemisphere. This pattern is largely driven by summer–winter variations in ionospheric conductivity, with some differences also arising from the asymmetric magnetic field geometry between the two hemispheres.

Sugar Maple and Red Maple Face-Off: Which Produces More and Sweeter Sap?

Among the species used for syrup production, sugar maple (Acer saccharum Marsh.) is preferred by producers, while red maple (Acer rubrum L.) is considered less productive in terms of sap yield and sugar content. This study aims to measure the volume and physicochemical characteristics of the sap produced from two red maples and two sugar maples during the 2023 sugar season in a commercial sugarbush in Laterrière (QC, Canada). Sap exudation was measured continuously with the gravity method using automatic rain gauges. Sap production was discontinuous and heterogeneous, reaching 2.6 L during the most productive day. No significant difference was found in the daily production between species, but we observed a difference in the cumulative sap production (7 L in red maple vs. 13.5 L in sugar maple) due to a longer period of sap exudation in the latter. Despite daily variations in pH, Brix values, sucrose concentration, osmolality, and conductivity, no differences in physicochemical characteristics were detected between species.

Effects of radial conductivity variation on the Ponomarenko dynamo

Effects of radial conductivity variation on the Ponomarenko dynamo

Detection and distinction of amino acids and post-translational modifications with gold nanojunctions.

Amino acids are fundamental building blocks of proteins, playing critical roles in medical diagnostics, environmental monitoring, and biomarker identification. The development of nanoscale electronic sensors capable of single-amino-acid recognition has gained significant attention due to their potential for label-free, real-time detection. In this study, we investigate the electronic transport properties of amino acids in two gold-based nanodevices with distinct architectures: a gold nanojunction and a gold-capacitor system. Using density functional theory (DFT) in combination with nonequilibrium Green's function (NEGF) calculations, we explore the sensing mechanism and conductance variations induced by different amino acids, including select phosphorylated variants. Each device was assigned a reference amino acid, F (M), for a capacitor (nanojunction) to differentiate its conductance from other molecules. Our results reveal distinct conductance that enables amino acid classification based on their electronic signatures, demonstrating that molecular discrimination is primarily governed by conductance variations as a function of the binding energy differences. The nanojunction exhibited remarkable differentiation for the amino acids S, pS, Y, and pY, rendering it especially proficient in distinguishing between structurally analogous molecules. These findings highlight the strong potential of gold-based nanodevices for precise amino acid detection, paving the way for advancements in biosensing technologies, molecular diagnostics, and biomedical applications.

Natural fiber‐reinforced light composites for the automotive industry

AbstractA European Directive on End‐of‐Life Vehicles (ELVs) established minimum reuse and recovery thresholds of automotive materials based on the weight of the vehicle, to improve fuel efficiency and therefore reduce the CO2 emissions. However, to replace a virgin material, recycled materials must guarantee adequate properties. In this work, low‐density lignocellulosic materials were adopted as “green” reinforcement for recycled polypropylene. In particular, variations in density, thermal resistance, mechanical properties, moldability, and thermal conductivity of a recycled polypropylene (PP) compounded with cork, hazelnut shells, and hazelnut skins (i.e. the cuticle that wraps the fruit inside the shell) were evaluated. The experimental results showed an improvement in thermal resistance and mechanical resistance at high temperatures, without substantially altering the density and thermal conductivity of PP. Among the various fillers analyzed, hazelnut skins seem to give the best results in terms of thermal and mechanical resistance and moldability.Highlights Cork, hazelnut skin and shell stand out as low‐density natural fillers for recycled polypropylene All the natural fillers increase the thermal stability of polypropylene The low‐density fillers enhance the mechanical properties of polypropylene at high temperatures Fillers do not substantially alter the density and thermal conductivity of polypropylene The addition of hazelnut skins allows an enhancement of the moldability of polypropylene

Factors affecting iron and manganese dissolution in groundwater: treatments with simultaneous oxidation and precipitation methods

ABSTRACT This study explores variations in groundwater (GW) pH, conductivity, ammonium, iron, and manganese parameters to reveal prospective interactions having an impact on the dissolved metal concentrations. To this end, bivariate and partial correlation procedures were applied to the data to obtain incisive evaluation. Besides characterisation efforts, photocatalytic iron and manganese removal experiments were also carried out with Ni-doped TiO2 nano-composite thin films (TFs) on real GW samples. UV-A (365 nm) An LED array was used as the illumination source. The experimental setup was based on three treatment routes including photocatalytic oxidation (PCO), NaOH-aided precipitation and PCO with simultaneous precipitation (SPCO-P). The main statistical analysis and treatment efforts have been performed on data and samples of a single well, respectively (N = 15). However, extended statistical analysis has also been performed on larger data groups (N = 1366) obtained from different GW sources as well. Analytical results have revealed that about 90% of iron and manganese were in oxidised forms which do not precipitate by simple pH regulation. Statistical analysis has also revealed significant interactions between metal concentrations and observed parameters depending on the level of pH and conductivity. Furthermore, the SPCO-P strategy has provided a four-fold increase in reaction rate (pseudo-first-order, kobs: 0.04 min−1). Removal efficiencies of iron and manganese also increased from 10% to 96% – 85%, respectively.

Rotating radial injection pattern for highly sensitive electrical impedance tomography of human lung anomalies.

Electrical Impedance Tomography (EIT) is a non-invasive technique used for lung imaging. A significant challenge in EIT is reconstructing images of deeper thoracic regions due to the low sensitivity of boundary voltages to internal conductivity variations. The current injection pattern is decisive as it influences the current path, boundary voltages, and their sensitivity to tissue changes. 
Approach. This study introduces a novel current injection pattern with radially placed electrodes excited in a rotating radial pattern. The effectiveness of the proposed pattern was investigated using a 3D computational model that mimics the human thorax, replicating its geometry and tissue electrical properties. To examine the detection of lung anomalies, models representing both healthy and unhealthy states, including cancer-like anomalies in three different positions, were developed.
The new pattern was compared to common patterns-Adjacent, Skip 1, and Opposite-using Finite Element Analysis (FEA). The comparison focused on the current density within lung nodules and the sensitivity to changes in anomaly positions. 
Main Results. Results showed that the new pattern achieved the maximum current density within anomalies compared to surrounding tissues, with peak values near the closest electrode pairs to the anomalies. Specifically, current density magnitudes reached 72.73 10^{-9} A.m, 145.24 10^{-9} A.m, and 26.43 10^{-9} A.m for the three different positions, respectively. Furthermore, the novel pattern's sensitivity to anomaly position changes surpassed the common patterns. These results demonstrate the efficiency of the proposed injection pattern in detecting lung anomalies compared to the common injection patterns.

Rotating radial injection pattern for highly sensitive electrical impedance tomography of human lung anomalies.

Electrical Impedance Tomography (EIT) is a non-invasive technique used for lung imaging. A significant challenge in EIT is reconstructing images of deeper thoracic regions due to the low sensitivity of boundary voltages to internal conductivity variations. The current injection pattern is decisive as it influences the current path, boundary voltages, and their sensitivity to tissue changes. 
Approach. This study introduces a novel current injection pattern with radially placed electrodes excited in a rotating radial pattern. The effectiveness of the proposed pattern was investigated using a 3D computational model that mimics the human thorax, replicating its geometry and tissue electrical properties. To examine the detection of lung anomalies, models representing both healthy and unhealthy states, including cancer-like anomalies in three different positions, were developed.
The new pattern was compared to common patterns-Adjacent, Skip 1, and Opposite-using Finite Element Analysis (FEA). The comparison focused on the current density within lung nodules and the sensitivity to changes in anomaly positions. 
Main Results. Results showed that the new pattern achieved the maximum current density within anomalies compared to surrounding tissues, with peak values near the closest electrode pairs to the anomalies. Specifically, current density magnitudes reached 72.73 10^{-9} A.m, 145.24 10^{-9} A.m, and 26.43 10^{-9} A.m for the three different positions, respectively. Furthermore, the novel pattern's sensitivity to anomaly position changes surpassed the common patterns. These results demonstrate the efficiency of the proposed injection pattern in detecting lung anomalies compared to the common injection patterns.

Effect of grain shape elongation in direction and perpendicular to current stream (conductive or insulator) on the electrical characteristics of mixtures

The shape elongation of grains, in mixtures, can have an effect on the electrical characteristics. Grain size and structural changes can impact the dielectric, and electrical properties of materials. The electrical properties of natural mixtures are influenced by their arrangement and shape. Insulating grains block potential pathways for electricity between electrodes. One key factor is grain shape elongation and how it aligns with the electric current. If the long part of the conductor grains lines up with the stream of current, then it will show high conductivity and an early critical percolation threshold. The critical percolation threshold decreases when the conductor is extended with the stream of current. Conductor elongated with the current stream increases the current flow. When the conductor is elongated perpendicular to the current stream, from sphere to needle, no perceptible alterations upon the associated critical threshold take effect. When the insulator is elongated with the stream of current the critical percolation threshold does not change significantly. The critical percolation threshold increases when insulator elongation perpendicular to the current direction. The elongated insulator perpendicular to the current’s stream hinders the current’s flow. The EMT offers a simulation to contain the variations in dielectric constant and conductivity across different concentrations. This is the first time to discuss the direction of elongation of conductor or insulator grains, in a mixture, in parallel or perpendicular to the stream of the current.

The Structural, Electrical and Dielectric Studies of CMC Based Biopolymer Gel Electrolytes for Ecofriendly Device Applications

ABSTRACTThe solution casting procedure has been effectively used to synthesize biopolymer gel electrolytes (BGEs) using carboxymethyl cellulose (CMC) and ammonium thiocyanate (NH4SCN). The XRD patterns of the bio‐based green emulsions (BGEs) have provided evidence of the non‐crystalline structure of the films. Optical micrographs of BGEs have revealed the formation of homogeneous gel electrolyte films. Complex impedance spectroscopy has been used to investigate the ion transport mechanism and dielectric relaxation dynamics of biopolymer gel electrolyte films over a wide range of temperatures. The conductivity of the gel electrolyte samples has been shown to rise with the amount of salt present. The optimum ionic conductivity, determined at room temperature, is σ = 3.97 × 10−3 Scm−1, and it is achieved in the gel electrolyte sample containing 35 wt% NH4SCN. The variation in ionic conductivity with temperature has shown a blend of Arrhenius and Vogel‐Tamman‐Fulcher (VTF) characteristics. An analysis has been conducted on the impedance data to investigate the ion transport process using the formalisms of ac conductivity, permittivity, and electric modulus. The dielectric impedance of the BGEs films has been used to determine the charge carrier density and mobility. The electrolyte with the best conductivity has shown a broad range of electrochemical stability, spanning from −1.49 to +1.27 V. The I‐t investigations has shown a high transference number (tion ~ 0.99), indicating that ions are the primary contributors to conductivity. The cyclic voltammetry tests have shown excellent reusability, indicating its potential use in devices, such as supercapacitors and rechargeable batteries.

Scaling Behavior of Ionic Conductance Dependent on Surface Charge Inside a Single-Digit Nanopore.

The ionic conductance in a charged nanopore exhibits a power-law behavior in low salinity-as has been verified in many experiments (G0∝c0α)-which is governed by surface charges. The surface charge inside a nanopore determines the zeta potential and ion distributions, which have a significant impact on ion transport, especially in a single-digit nanopore with potential leakage. However, precisely measuring surface charge density in a single-digit nanopore remains a challenge. Here, we propose a methodology for exploring the power-law variation of ionic conductance, with potential leakage taken into account. We conducted experiments to measure the ionic current using silicon nitride nanopores and employed a continuous theory to explore the relationship between pore-bound concentration and surface charges. Considering that the influence of potential leakage on concentration follows a power-law relationship, we established a coefficient (α) to examine the controlling factors of potential leakage and modified the conductance model to obtain the ion mobility inside a nanopore.