Total Electrical Conductivity Research Articles

Quality Assessment and Authentication of Raw Honey-Available at Local Markets of Punjab

Honey have delightful sweetness, propitious nutrition, antioxidant, bioactive, viscous golden yellow substances and used widely in food, beverages, medicinal research against treatment of a number of infections caused by microbes (bacteria, viruses, and parasites) due to antifungal and antibacterial properties and its complex carbohydrates, vitamins, minerals, organic acids, phenolic compounds and anti-oxidants nature. Aim of this study was to identify adulteration in honey samples collected from local stores of different regions of Punjab, Pakistan. Seven honey samples were procured and analyzed for hydroxyl methyl furfural (HMF) contents, moisture content, protein contents, pollens, ash contents, total sugar contents (sucrose, non-reducing and reducing), viscosity, total soluble solids, pH, acidity and electrical conductivity. Results ranged for moisture contents from 19.97 to 25.6%, total soluble solids (TSS) ranged from 74.4 to 80, pH 2.4-4, protein contents from 0.29 to 0.44%, ash contents from 0.15 to 0.45%, pollens from 22.4 to 74.7, viscosity from 376.7 to 1030cP/s, total acidity from 17 to 41.9 meq/kg, total sugars from 66.2 to 78.2%, reducing sugars from 58.4 to 72.3%, non-reducing sugars from 4.6 to 8.8% and HMF contents ranged from 15.7-35mg/kg. Higher amount of HMF present in honey is the indication of heating and lower quality honey. The results were associated with standards and specifications of “Pakistan Pure Food Rules”. 40% samples did not meet criteria. The accurate quantification should employ for production of high quality honey with strict national legislations and monitoring on apiculture to avoid mixing of adulterants in honey.

Groundwater Quality Assessment and Modeling Using Water Quality Index and Mathematical Models: Case Study of Bam Province, Burkina Faso

In light of groundwater's fundamental role in providing drinking water to populations in the Sahel, its management and monitoring are vital for predicting and mitigating future crises. The goal of this study is to assess the groundwater quality in Bam province using the Water Quality Index (WQI), and to predict these indices through the application of Artificial Neural Networks (ANN) and traditional Multiple Linear Regression (MLR) techniques. In this context, a variety of physicochemical parameters such as Total Hardness (TH), pH, Electrical Conductivity (EC), calcium, magnesium, sodium, potassium, ammonium, bicarbonate, chloride, sulphate, nitrite, nitrate, phosphorus, and fluoride were collected from 154 boreholes, analysed, and used to calculate the WQIs. These parameters were employed as inputs, while the WQIs served as the output target for the models. The data were arranged in ascending order based on the indices, with 70% of the data reserved for training the models and 30% for testing. The groundwater quality in the study area, characterized by its geological heterogeneity and discontinuous fractures affecting groundwater flow, is predominantly excellent, with 95.45% of the samples having WQIs below 50. The remaining 4.55% is split between good (3.90%) and poor (0.65%) quality, with WQIs ranging from 50–100 and 100–200, respectively. In terms of predictive modeling, the ANN method provided the most accurate results, with R² (coefficient of correlation) = 0.99, RMSE (Root Mean Scare Error) = 0.0037, and MAE (Mean Absolute Error) = 0.0032 for the training set, and R² = 0.96, RMSE = 4.46, and MAE = 3.27 for the testing set. By comparison, the traditional method showed lower accuracy with R² = 0.61, RMSE = 2.71, MAE = 2.02 for the training set, and R² = 0.93, RMSE = 7.97, MAE = 6.32 for the testing set. The slight decrease in model accuracy during the testing phase is attributed to the challenge of modeling strong indices with weaker ones, as well as the geological heterogeneity and discontinuities that complicate groundwater quality prediction. However, this does not affect the model’s ability to predict extreme situations, such as water pollution events.

Thermoelectric and electrical properties of triple-conducting multicomponent oxides based on substituted barium cerate-zirconate.

Multicomponent oxides often have exceptional thermal stability and interesting electronic properties. The present work presents the thermoelectric and electrical properties of the Ba(Zr0.2Hf0.2Sn0.2Ti0.2Fe0.2)O3-δ and Ba(Zr0.1Hf0.1Sn0.1Ti0.1Co0.1Ce0.1Bi0.1Fe0.1Y0.1Zn0.1)O3-δ multicomponent perovskites. Single-phase cubic perovskites were synthesized using the solid-state reaction method. They were characterized using X-ray diffraction, drop-solution calorimetry, and thermogravimetry methods. The total electrical conductivity and Seebeck coefficient measurements were performed in dry and wet air at temperatures between 600 and 1050 K. It was found that Ba(Zr0.1Hf0.1Sn0.1Ti0.1Co0.1Ce0.1Bi0.1Fe0.1Y0.1Zn0.1)O3-δ is thermodynamically less stable than Ba(Zr0.2Hf0.2Sn0.2Ti0.2Fe0.2)O3-δ. Moreover, this oxide incorporates a higher amount of water and exhibits higher conductivity and lower Seebeck coefficient. Charge transport in both perovskites can be assigned to the small-polaron hopping process via electron holes. An interesting temperature dependence of the Seebeck coefficient was found and, at temperatures above 750 K, related to hopping between energetically inequivalent states.

Effect of Maleic Hydrazide Foliar Application on Biochemical Parameters and Phytohormonal Variations in Groundnut (cv. Dh 86)

This study assessed the impact of varying concentrations of maleic hydrazide (MH) on seed biochemical parameters in groundnut. Where increasing MH concentrations resulted with least total dehydrogenase activity (0.505 OD value at A480) and electrical conductivity (200 µS cm⁻¹), and increased phenol content (3.48 mg/g) at foliar spray of MH @ 3000 ppm over the control (0.822 OD value at A480, 257 µS cm⁻¹, 2.80 mg/g) respectively. Further this study examines the impact of MH foliar spray at 3000 ppm, unsprayed control and a dormant check (Dh 8) on groundnut seed phytohormones, comparing results to an unsprayed control. Abscisic acid (ABA) levels increased from 15.6 ng/g in unsprayed control to 45.96 ng/g in MH treated seeds and 74.58 ng/g in Dh 8, promoting dormancy. Gibberellins (GA3) reduced by 98.7% in MH treated seeds (0.88 ng/g) and by 99.2% in Dh 8 (0.54 ng/g). Auxins (IAA) decreased 86.8% in MH treated seeds (1.15 ng/g) and 22.9% in Dh 8 (6.70 ng/g) relative to unsprayed control (8.71 ng/g). These shifts highlight the distinctive effects of MH and dormant cultivar Dh 8 on dormancy regulation compared to control.

Y2T2O7-Based Pyrochlores As Alternative Materials for Diffusion Barrier Layer at the Fuel Electrode-Electrolyte Interface in SOFC/SOEC

The introduction of a ceria-based diffusion barrier layer between electrolyte and Sr-containing oxygen electrode is a common approach to avoid the formation of undesirable low-conducting SrZrO3 phase at the electrolyte/electrode interface with negative effects on the performance of solid oxide cell (SOFC/SOEC). However, partial reduction of cerium cation to 3+ oxidation state under reducing conditions induces noticeable chemical expansion of doped ceria ceramics and may cause delamination of the ceria-based buffer layer applied at the fuel electrode side of solid oxide cell. The present work explores pyrochlore-type Y2Ti2O7-based titanates as alternative interlayer materials operating at the interface between the electrolyte and Sr-containing fuel electrodes.A- and/or B-site Y2T2O7-based compositions including (Y0.9Ca0.1)2Ti2O7, (Y0.85Ca0.15)2Ti2O7, (Y0.9Ca0.1)2(Ti0.6Zr0.4)2O7, (Y0.9Ca0.1)2(Ti0.9Mn0.1)2O7, (Y0.9Mg0.1)2Ti2O7, and Y2(Ti0.9Mg0.1)2O7 were selected as candidate materials. The materials were prepared by solid reaction method and sintered at 1600-1700°C in air. The characterization included structural and microstructural studies, controlled-atmosphere dilatometry, and measurements of electrical transport properties (electrical conductivity as a function of temperature and oxygen partial pressure by AC impedance spectroscopy, oxygen-ion transference numbers by modified EMF method).The results showed that the solubility of calcium cations in the yttrium sublattice is limited to 10 at.%. Apart from (Y0.9Ca0.1)2Ti2O7, only (Y0.9Ca0.1)2(Ti0.6Zr0.4)2O7 and (Y0.9Mg0.1)2Ti2O7 were phase-pure pyrochlores, while other materials contained different types of secondary phases. Total electrical conductivity of single-phase ceramics in air increased in the row (Y0.9Ca0.1)2(Ti0.6Zr0.4)2O7 < (Y0.9Mg0.1)2Ti2O7 < (Y0.9Ca0.1)2Ti2O7 reaching 0.02 S/cm at 800°C (Fig.1). The conductivity is predominantly oxygen-ionic at intermediate oxygen pressures, while minor contributions of p-type and n-type electronic transport increase under oxidizing and reducing conditions, respectively. Average oxygen-ion transference numbers under air/(10%H2-N2) gradient at 800°C were 0.995 for (Y0.9Ca0.1)2Ti2O7 and 0.983 for (Y0.9Mg0.1)2Ti2O7. Pyrochlore-type titanate ceramics showed moderate thermal expansion coefficients, 10.2-10.4 ppm/K, under both oxidizing and reducing conditions at 25-1100°C and negligible chemical expansion. On the contrary, gadolinia-doped ceria Ce0.9Gd0.1O2-δ ceramics underwent a substantial chemical expansion and cracking on heating above 700-800°C in 10%H2-N2 atmosphere.(Y0.9Ca0.1)2Ti2O7 was selected as the preferred interlayer candidate material with the highest ionic conductivity. A procedure for the fabrication of a thin interlayer in a model electrolyte-supported button cell was developed. Chemical compatibility was verified in contact with solid electrolyte, yttria-stabilized zirconia, and model fuel electrode materials, Sr0.85Pr0.15TiO3-δ and SrFe0.75Mo0.25O3-δ.Figure 1. Electrical conductivity of pyrochlore-type Y2T2O7-based ceramics in air.Acknowledgments: This work was done within the scope of project CLEARNESS (funded by the ERA-MIN3 program), project SFRH/BD/150704/2020 (funded by the FCT), and project CICECO-Aveiro Institute of Materials (UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020) financed by national funds through the FCT/MCTES (PIDDAC), Portugal. Figure 1

Modified Debye-Hückel-Onsager theory for electrical conductivity in aqueous electrolyte solutions: Account of ionic charge nonlocality.

This paper presents a mean field theory of electrolyte solutions, extending the classical Debye-Hückel-Onsager theory to provide a detailed description of the electrical conductivity in strong electrolyte solutions. The theory systematically incorporates the effects of ion specificity, such as steric interactions, hydration of ions, and their spatial charge distributions, into the mean-field framework. This allows for the calculation of ion mobility and electrical conductivity, while accounting for relaxation and hydrodynamic phenomena. At low concentrations, the model reproduces the well-known Kohlrausch's limiting law. Using the exponential (Slater-type) charge distribution function for solvated ions, we demonstrate that experimental data on the electrical conductivity of aqueous 1:1, 2:1, and 3:1 electrolyte solutions can be approximated over a broad concentration range by adjusting a single free parameter representing the spatial scale of the nonlocal ion charge distribution. Using the fitted value of this parameter at 298.15K, we obtain good agreement with the available experimental data when calculating electrical conductivity across different temperatures. We also analyze the effects of temperature and electrolyte concentration on the relaxation and electrophoretic contributions to total electrical conductivity, explaining the underlying physical mechanisms responsible for the observed behavior.

Infant body composition trajectories differ by in utero exposure to gestational diabetes mellitus: a prospective cohort from birth to 12 months

BackgroundInfants exposed to gestational diabetes mellitus (GDM) in utero are known to have higher fat mass (FM) and less fat-free mass (FFM) at birth, but little is known about how their adiposity changes over the first year of life. ObjectivesWe identified growth and body composition patterns across the first year and evaluated for differences by GDM exposure status. MethodsAmong 198 infants (52% GDM exposed), growth and body composition with total body electrical conductivity were obtained from birth to 1 y. Latent class mixed modeling (LCMM) trajectories were fit for weight-, length-, and body mass index (BMI)-for-age World Health Organization z-scores, as well as percent body fat, FM, and FFM. Adjusted associations between GDM with trajectory classes were evaluated with multiple logistic regression. ResultsAt birth, infants exposed to GDM had higher FM, higher percent body fat, and a higher BMI compared with infants unexposed. A larger proportion of infants exposed to GDM were classified into LCMM growth trajectory classes that experienced less FM (67% GDM exposed) and percent body fat gain (79% GDM exposed), compared with the other classes (Χ2P values <0.05). In adjusted models, infants exposed to GDM were 69% less likely (Relative Risk Ratios (RRR) = 0.39, 95% confidence interval: 0.11, 0.82) to belong in the highest FM trajectory that reached 4 kg of FM at 1 y of age. In adjusted models, GDM exposure was not associated with FFM, weight-, length-, or BMI-for-age trajectories. ConclusionsIn a cohort of infants exposed and unexposed to GDM in utero, infants exposed had increased weight, FM, and percent body fat at birth. However, more infants exposed to GDM had less fat accrual over the first year of life, compared with those unexposed. The long-term effects of these growth patterns in the first year challenge current concepts and support further investigation of neonatal body composition.

Stochastic Processes Dominate the Assembly of Soil Bacterial Communities of Land Use Patterns in Lesser Khingan Mountains, Northeast China.

To meet the demands of a growing population, natural wetlands are being converted to arable land, significantly impacting soil biodiversity. This study investigated the effects of land use changes on bacterial communities in wetland, arable land, and forest soils in the Lesser Khingan Mountains using Illumina MiSeq 16S rRNA sequencing. Soil physicochemical properties and enzyme activities were measured using standard methods, while microbial diversity was assessed through sequencing analysis. Our findings revealed that forest soils had significantly higher levels of total potassium (2.62 g·kg-1), electrical conductivity (8.22 mS·cm-1), urease (0.18 mg·g-1·d-1), and nitrate reductase (0.13 mg·g-1·d-1), attributed to rich organic matter and active microbial communities. Conversely, arable soils showed lower total potassium (1.94 g·kg-1), reduced electrical conductivity, and suppressed enzyme activities due to frequent tilling and fertilization. Wetland soils exhibited the lowest values primarily due to water saturation, which limits organic matter decomposition and microbial activity. Land use changes notably reduced microbial diversity, with conversion from forest to arable land leading to habitat loss. Forest soils supported higher abundances of Proteobacteria (37.59%) and Actinobacteriota (34.73%), while arable soils favored nitrogen-fixing bacteria. Wetlands were characterized by chemoheterotrophic and anaerobic bacteria. Overall, these findings underscore the profound influence of land use on soil microbial communities and their functional roles, highlighting the need for sustainable management practices.

Thermoelectric and electrical transport properties of mixed-conducting multicomponent oxides based on Ba(Zr,Ce)O3-δ

In this work, the chosen physicochemical properties of single-phase multicomponent oxides BaTi1/8Fe1/8Co1/8Y1/8Zr1/8Sn1/8Ce1/8Hf1/8O3-δ and BaTi1/9Fe1/9Co1/9Y1/9Zr1/9Sn1/9Ce1/9Hf1/9Bi1/9O3-δ were studied. The microstructure of the compounds strongly depended on the presence of bismuth in the structure. The electrical transport studies showed a level of electrical conductivity of ∼10−3 - 10−2 S/cm in the temperature range 673–1073 K. Electrical conductivity was thermally activated and the dominant conduction mechanism was the hopping of small polarons. Moreover, total electrical conductivity changes in the dry and humidified atmosphere at lower temperatures due to the presence of protonic defects in the structure. Thermoelectric measurements showed a relatively high value of the Seebeck coefficient for studied ceramics. Its values ranged between 50 and 250 μV/K depending on the sample and temperature. The Seebeck coefficient sign was positive, meaning that electron holes and/or oxygen vacancies were predominant charge carriers in oxidizing atmospheres. Additionally, the Seebeck coefficient was found to be different in the humidified atmosphere which indicates an influence of protonic defects on thermoelectric transport. The obtained power factor Pf turned out to be low and dependent on the presence of protonic defects in the structure. This indicates, that the efficiency of the MOs-based operating thermoelectric generators can be controlled by changing the partial pressure of water vapor.

Mining and urbanization affect river chemical water quality and macroinvertebrate communities in the upper Selenga River basin, Mongolia (revised version)

Mongolia is a country with a quickly growing economy mainly based on the mining of gold, copper, coal, and other minerals. Mining, urbanization, and agriculture impact the water quality in the upper Selenga River basin in northern Mongolia, which is the center of the Mongolian economy. Previous measurements of pollution loads were alarming, but restricted to chemical measurements. Here, for the first time, we combine freshwater biomonitoring and laboratory water quality data across a broad gradient of water quality and land use intensity. We track the effects of different types of pollution on aquatic invertebrates and test their use as bioindicators. We collected water samples, environmental parameters, and macroinvertebrates at 36 sampling sites at the rivers of Tuul, Kharaa, and Orkhon and their tributaries Sugnugur, Boroo, Sharyn Gol, Gatsuurt, and Yeröö. PCA of catchment water quality distinguished three groups of pollutants prevalent at the sites, (1) nutrients, (2) salt ions (Cl−, Na+, Mg2+, So42−, Ca2+) and mining by-products (B, Sr, U, Mo), and (3) (heavy) metals, which often exceeded regulatory standards. We recorded a total of 59 macroinvertebrate taxa belonging to 31 families in seven insect orders plus Amphipoda and Gastropoda. Species diversity declined with higher impact. Five environmental factors structured macroinvertebrate community composition in RDA: elevation of sample location, site total nitrogen, dissolved oxygen, electrical conductivity, and water chemistry. We conclude that macroinvertebrate communities are an appropriate and inexpensive tool for monitoring water quality in Mongolia and suggest government action to establish a long-term monitoring program.

Assessment of Ecological Status of Streams by Macrophyte Biological Index in Kahramanmaras Province (Turkiye)

ABSTRACTClimate change and human‐induced pollution threaten freshwater systems. In the present study, it was aimed to evaluate the macrophytes‐stressor relations and ecological quality status based on the Macrophyte Biological Index for Rivers (Indice Biologique Macrophytique en Rivière [IBMR]) index of 25 streams sampled in the spring (rainy) and autumn (dry) seasons of 2021 in Kahramanmaraş province. A total of 53 macrophyte taxa were identified, and Lycopus europaeus, Mentha longifolia, Mentha aquatica, Juncus sp., Cladophora glomerata and Carex sp. were common taxa. Canonical correspondence analysis results indicated significant effects of total phosphorus, nitrite, dissolvent oxygen, electrical conductivity, bromate and boron on the distribution of macrophytes among streams, which was supported by results of the weighted average regression analysis. The IBMR indicated that the ecological quality status varied from bad to good in the studied streams. Deterioration in the water quality of a few ecosystems in the dry season compared to the rainy season was elucidated by the IBMR, which also distinguished the ecological conditions of streams. Results highlight that macrophyte species are one of the most important bioindicators to evaluate the ecological status of streams in Kahramanmaraş province due to their sensitivity to changes in environmental conditions. All suggest that IBMR can be used to evaluate the ecological health of streams in the Mediterranean region.

A focus on the Chinese stingless bee honey (Hymenoptera, Apidae, Meliponini): Exploring physicochemical parameters for establishing quality standards

Stingless bee honey (SBH) is the most important product from stingless bee colonies with great economic value and health benefits. Nevertheless, there is little information on the physiochemical parameters of Chinese SBH, which also limits its utilization and quality control. In the period 2019–2023, we collected 89 Chinese SBH samples produced by five stingless bee species from four provinces in China. We performed comprehensive assessments of various SBH physicochemical indicators. These parameters include moisture, trehalulose, sucrose, fructose, glucose, total soluble solids, Baumé, ash, pH, electrical conductivity, 5-hydroxymethylfurfural, and free acidity. Our data revealed that the physicochemical parameters of Chinese SBH are consistent with earlier reported results from other countries. Notably, the Chinese SBH exhibited a relatively low level of 5-hydroxymethylfurfural (0–9.64 mg/kg), sucrose (0–0.43 g/100 g), and no diastase activity was detected. Chinese SBH was rich in trehalulose (4.26–37.65 g/100 g). After comparing these indexes with published data and with Australian/Malaysian samples, we proposed a new food standard for regulations of Chinese SBHs. These findings provide crucial insights into the Chinese SBH and contribute significantly to developing quality control and global standards for SBH.

Temperature-dependent dielectric measurements of polypyrrole/zinc cobalt oxide nanocomposites by impedance spectroscopy

This study characterizes the conduction mechanism in Zinc Cobalt oxide/Polypyrrole nanocomposites (ZCO/PPy NCs) concerning temperature (303–453 K) and frequency (100 Hz–1 MHz). To obtain the ZCO/PPy nanocomposites for the experiments, we used the in-situ chemical polymerization technique to disseminate varying weight percentages of ZCO nanoparticles (ZCO NPs) in the PPy matrix. The total electrical conductivity graph consists of a step-like feature of a plateau and dispersive regimes. The dispersive zone, which follows Jonscher's power law, correlates to AC conductivity, whereas the plateau region, which corresponds to DC conductivity, is thermally activated. The extracted DC conductivity values are of the order of 10‐4 S/m at 303 K. The conduction mechanism in ZCO/PPy nanocomposites is depicted by the Non-Overlapping Large Polaron Tunneling (NSPT) model. The dielectric studies confirm the non-Debye-like relaxation in PPy and ZCO/PPy NCs. In addition, the complex impedance and equivalent circuit analysis showed maximum contribution from grain and grain boundaries. The grain and grain boundary resistances are of the order of 103 Ω, depicting the electrical homogeneity in the PPy and ZCO/PPy nanocomposites.

Neutrosophic Approach to Water Quality Assessment: A Case Study of Gomati River, the Largest River in Tripura, India

This study addresses the complexity of assessing river water quality, a multifaceted process influenced by numerous water quality parameters (WQPs) characterized by inherent uncertainties and diverse judgment information from decision-makers. These uncertainties and diverse judgment information can be effectively represented and simulated using Neutrosophic sets. In this study, we propose an effective water pollution rating system, the Neutrosophic water quality index (NWQI), to derive a water pollution score (NWQI-score) for rating water pollution levels. We demonstrate the application of our methodology through an assessment of water quality indices for rating pollution in the Gomati River, the largest river in Tripura, India. Using the NWQI, we highlight the NWQI score as a pivotal indicator for evaluating the river's water quality. For assessing water quality, we consider six crucial parameters, namely Total hardness, Biochemical oxygen demand, Total suspended solids, Electrical conductivity, pH, and total dissolved solids, sampled at five strategic sites along the river. Sampling was conducted from January 2024 to July 2024, guided by the distribution of waste discharge points. Finally, we conclude the study, summarizing findings and suggesting future research directions.

Distribution Characteristics of Nitrogen-Cycling Microorganisms in Deep-Sea Surface Sediments of Western South China Sea.

Nitrogen-cycling processes in the deep sea remain understudied. This study investigates the distribution of nitrogen-cycling microbial communities in the deep-sea surface sediments of the western South China Sea, using metagenomic sequencing and real-time fluorescent quantitative PCR techniques to analyze their composition and abundance, and the effects of 11 environmental parameters, including NH4+-N, NO3--N, NO2--N, PO43--P, total nitrogen (TN), total organic carbon (TOC), C/N ratio, pH, electrical conductivity (EC), SO42-, and Cl-. The phylum- and species-level microbial community compositions show that five sites can be grouped as a major cluster, with sites S1 and S9 forming a sub-cluster, and sites S13, S19, and S26 forming the other; whereas sites S3 and S5 constitute a separate cluster. This is also evident for nitrogen-cycling functional genes, where their abundance is influenced by distinct environmental conditions, including water depths (shallower at sites S1 and S9 against deeper at sites S13, S19, and S26) and unique geological features (sites S3 and S5), whereas the vertical distribution of nitrogen-cycling gene abundance generally shows a decreasing trend against sediment depth. Redundancy analysis (RDA) exploring the correlation between the 11 environmental parameters and microbial communities revealed that the NO2--N, C/N ratio, and TN significantly affect microbial community composition (p < 0.05). This study assesses the survival strategies of microorganisms within deep-sea surface sediments and their role in the marine nitrogen cycle.

Developing water quality and land use surrogates to predict endocrine-disrupting chemical profiles in a highly urbanized river basin

This study investigated geospatial distributions of endocrine-disrupting chemicals (EDCs) in the waters of the Dongjiang River and their associations with anthropogenic activities. Fifteen EDCs, with total concentrations in the river water of 149–2525 ng/L were detected, with bisphenol-A, 4-nonylphenol, 4-tert-octylphenol, p-hydroxybenzoic acid, and methylparaben being the five predominant EDCs. The total estrogen concentration was high downstream and significantly correlated with the spatial distribution of urban land use, wastewater discharge, population, and gross domestic product, indicating human activities have increased estrogen levels and threatened ecological health. The total risk quotient indicated a high ecological risk of estrogens to fish and a moderate to high ecological risk of personal care products to algae. Estrone, triclosan, bisphenol-A, 4-nonylphenol, and 4-tert-octylphenol were categorized as priority pollutants, which required special concern. Triclosan and triclocarban can serve as reliable chemical indicators for predicting EDC levels based on correlation analysis. The crucial factors affecting EDC levels were identified through the Mantel test and predictor importance was quantified using a multiple regression model, which can help predict occurrences and geospatial distributions of EDCs. Total phosphorus and electrical conductivity were the major predictors of EDC levels, providing promising indicators for monitoring EDCs in river water. Urban land proportion significantly affected phenolic environmental estrogens, natural estrogens, and disinfectants. In the main stream, urban population, urbanization rate, and gross domestic product influenced phenolic environmental estrogen levels. A mini-review of the global distribution of EDCs in river water revealed that income and population differences among countries affect their occurrence, suggesting socioeconomic factors should be considered to mitigate EDC pollution.

Electrical conductivity model for reactive porous media under partially saturated conditions with hysteresis effects

The electrical conductivity of a porous medium is strongly controlled by the structure of the medium at the microscale as the pore configuration governs the distribution of the conductive fluid. The pore structure thus plays a key role since different geometries translate in variations of the fluid distribution, causing different behaviors measurable at the macroscale. In this study, we present a new physically-based analytical model derived under the assumption that the pore structure can be represented by a bundle of tortuous capillary tubes with periodic variations of their radius and a fractal distribution of pore sizes. By upscaling the microscale properties of the porous medium, we obtain expressions to estimate the total and relative electrical conductivity. The proposed pore geometry allows us to include the hysteresis phenomenon in the electrical conductivity estimates. The variations on these estimates caused by pore structure changes due to reactive processes are accounted by assuming a uniform dissolution of the pores. Under this hypothesis, we describe the evolution of the electrical conductivity during reactive processes. The expressions of the proposed model have been tested with published data from different soil textures, showing a satisfactory agreement with the experimental data. Hysteretic behavior and mineral dissolution are also successfully addressed. By including hysteresis and mineral dissolution/precipitation in the estimates of the electrical conductivity, this new analytical model presents an improvement as it relates those macroscopic physical phenomena to its origins at the microscale. This opens up exciting possibilities for studies involving electrical conductivity measurements to monitor water movement, and hysteretic and reactive processes in porous media.

Optimizing the thermoelectric performance of Bi-Sb-Te thin films through compositional engineering

The objective of the present investigation was to systematically investigate the structural and thermoelectric (TE) properties of BixSb2-xTe3 thin films with varying content of Bi. We investigated the impact of different atomic percentages of Bi (4, 6, 8 at. %) on the properties of carrier transport and TE performance. In general, the Seebeck coefficient remained consistent across the thin films. For the 8 at. % Bi thin film, the Seebeck coefficient and electrical conductivity were measured at 230 μV/K and 730 S/cm, respectively, at room temperature. These values were more than 20 times greater than the electrical conductivity observed in the thin films with compositions of 6 and 4 at. % Bi. As a result, the Bi-Sb-Te compound exhibited a TE power factor (PF) of 38x10−4 W/mK2 at 40 °C, surpassing the PFs observed in previous compositions. The analysis of surface microstructure, combined with atomic force microscopy and Kelvin probe microscopy images, revealed that the transport of carriers in films with high Bi content was impeded by the size of particles and scattering sites. On the other hand, an augmentation in Bi content promoted the transfer of charge through crystalline regions, hence improving the mobility of carriers and the total electrical conductivity. The aforementioned results emphasize the significant influence of Bi content on the electrical properties of semiconductors and demonstrate the effectiveness of compositional engineering based on Bi content in the development of TE materials with superior performance. The present study investigates the influence of Bi content on the electrical properties of Bi-Sb-Te thin films, demonstrating that compositional adjustments based on Bi content can impact the performance of TE materials. These findings contribute to the understanding of material optimization in the field of TE.

Magnetohydrodynamic and Aerodynamic Assessment of a 70° Spherecone at Mars and Venus

An electrical conductivity database for continuum flow in a CO2 atmosphere over a 70° spherecone was created using the Data Parallel Line Relaxation Code computational fluid dynamics software to inform development of future magnetohydrodynamic subsystems at Venus and Mars. Sixteen freestream conditions were considered at Mars with atmospheric relative velocities from 5 to 8 km/s and altitudes between 20 and 80 km. Sixteen freestream conditions were considered at Venus with atmospheric relative velocities from 9 to 12 km/s and altitudes between 85 and 115 km. Results indicate that the total electrical conductivity in the flow volume always increases as velocity increases. At low velocities, the electrical conductivity is higher at high altitudes whereas, at high velocities, the electrical conductivity is higher at low altitudes. Three of the 80 km altitude computational fluid dynamics solutions show good agreement with direct simulation Monte Carlo results. In general, computational fluid dynamics predicts thinner shocks, higher electron number density, and similar vibrational temperatures to direct simulation Monte Carlo. The magnetohydrodynamic force was calculated at both Mars and Venus. Results indicate there may not be sufficient control authority to use magnetohydrodynamics as a trajectory control mechanism at Mars without artificially increasing the electrical conductivity of the flow, but there may be appreciable control authority for a drag-modulated aerocapture at Venus.

Chemical and physical characteristics of wheat root mucilage influenced by Serendipita indica symbiosis: a comparison among four cultivars.

Although there is evidence to suggest that the endophytic fungus Serendipita indica plays a crucial role in enhancing plant tolerance against biotic/abiotic stressors, less is known about the impacts of this symbiosis association on root mucilage chemical composition and its physical functions. The mucilage of inoculated and non-inoculated seedlings of four wheat cultivars (i.e., Roshan, Ghods, Kavir and Pishtaz) were extracted using an aeroponic method. Total solute concentration (TCm), carbon content (Cmucilage), electrical conductivity (EC), pH, fatty acids, surface tension (σm), and viscosity (ηm) of mucilage were measured. Ghods and Kavir had the highest and lowest root colonization percents, respectively. Saturated fatty acids, including palmitic and stearic acids, were dominant over unsaturated fatty acids in wheat root mucilage. However, their compositions were significantly different among wheat cultivars. S. indica colonization, especially for Ghods, increased the TCm, Cmucilage, and palmitic acid. Moreover, root mucilage of S. indica-inoculated Ghods had lower σm and greater ηm. An increased amount of powerful surfactants like palmitic acid in the mucilage of S. indica inoculated treatments led to lower σm and greater ηm. Such studies provide further support for the idea that plant-released mucilage plays a major role in modifying the physical environment of the rhizosphere. This knowledge toward truly understanding the rhizosphere can be potentially used for improving the rhizosphere soil quality and increasing crop growth and yield.