Search Results (3,295)

Two-dimensional (2D) organic–inorganic hybrid perovskites exhibit coupled ionic, electronic, and electromechanical responses that can strongly influence local charge transport. Here, solution-processed mixed-halide butylammonium lead perovskite crystals were mechanically exfoliated and investigated using X-ray diffraction, atomic force microscopy, piezoresponse force microscopy (PFM), and conductive atomic force microscopy (c-AFM). PFM measurements under −5, 0, and +5 V revealed clear bias-dependent changes in amplitude and phase, indicating an electric field-sensitive local electromechanical response. Local c-AFM measurements showed nonlinear bipolar hysteresis, with a pronounced increase in current near +7–8 V and a decrease near −7 to −6 V during the subsequent negative sweep. Because the crystals are mixed ionic–electronic conductors and the nanoscale tip–sample junction introduces substantial injection and contact barriers, the observed behavior is interpreted as resistive switching-like conductivity modulation, rather than definitive ferroelectric switching. The results are consistent with the combined contributions of charge injection, trap filling, possible ionic redistribution, and piezoelectricity-associated modulation of the local transport barrier. These findings provide nanoscale insight into electric field-dependent electromechanical and out-of-plane conductive behaviors in layered 2D hybrid perovskites. Full article

Conventional carbon-black-based low-resistance anti-corona coatings can exhibit electrical properties that are sensitive to filler dispersion, particle spacing, interfacial conditions, and temperature-induced structural rearrangement. In this study, nano antimony-doped tin oxide (ATO) was surface-modified with γ-aminopropyltriethoxysilane (KH550) and used to partially replace carbon black in an E-51 epoxy matrix. The total hybrid-filler loading was fixed at 10 wt% relative to the mass of E-51 epoxy resin, while the ATO/carbon black mass ratio was varied from 0:10 to 10:0. Fourier transform infrared spectroscopy was used to examine the introduction of KH550-derived organosilane species onto ATO, and the coating formulations were screened by measuring surface resistance and corona inception voltage (CIV) under a needle–plate electrode configuration. The selected A3C7 coating was further compared with a commercial carbon-black-based low-resistance anti-corona coating through scanning electron microscopy and thermal cycling between 25 and 150 °C. A3C7 exhibited a surface resistance of (1.17 ± 0.07) × 10⁴ Ω and the highest CIV of 2.58 ± 0.04 kV, representing a 40.1% increase relative to the carbon-black-only A0C10 coating. Relatively uniform circular or elliptical micron-scale features were observed on the A3C7 surface; however, their chemical origin could not be determined by conventional SEM. After 50 thermal cycles, the relative resistance change in A3C7 was 12.62% ± 1.19%, markedly lower than the 63.95% ± 6.76% obtained for the commercial coating. The corresponding CIV retentions were 91.86% and 82.40%, respectively. These results demonstrate that partial replacement of carbon black with KH550-modified ATO can provide a favorable balance among low surface resistance, increased CIV, and improved thermal-cycling electrical stability. The microscopic origin of this behavior remains to be clarified by direct characterization of filler distribution and conductive pathways. Full article

Medicinal and aromatic plants are important sources of secondary metabolites used in pharmaceutical, cosmetic, nutraceutical, and health-related applications. However, the phytochemical and bioactive composition of plant raw materials is often highly variable because it is influenced by genotype, developmental stage, cultivation environment, and post-harvest conditions. Controlled environment agriculture (CEA) offers an opportunity to reduce this variability by regulating key aboveground and root-zone factors under reproducible cultivation conditions. This review synthesizes recent research on how environmental control in CEA can influence plant metabolism, biomass formation, phytochemical accumulation, and production value in medicinal and aromatic plants. Particular attention is given to light spectrum and quantity, UV radiation, air temperature, vapor pressure deficit, CO₂ concentration, nutrient solution composition, pH, electrical conductivity, root-zone temperature, salinity, and chemical elicitors. The review distinguishes general environmental regulation from controlled elicitation: some factors primarily support growth, resource-use efficiency, and product consistency, whereas others can be applied as defined stimuli to activate stress-related or defense-related secondary metabolism. Evidence indicates that these factors can modify phenolics, flavonoids, terpenoids, alkaloids, essential-oil constituents, and other bioactive compounds. However, reported phytochemical changes should not be evaluated only by metabolite concentration but also by biomass production, resource input, technological feasibility, and batch-to-batch consistency. The review also highlights the need to move from single-factor optimization toward integrated, plant-informed control strategies that account for factor interactions, treatment timing, genotype specificity, non-destructive feedback, and realistic energy and resource constraints. Integrating plant physiology, phytochemistry, environmental control, and production technology may support the development of CEA as a framework for developing phytochemical standardization protocols and more reproducible production of high-value medicinal plant material, although further validation across batches, production cycles, and resource inputs is required. Full article

The electrical response of conductive textile structures to liquid exposure was investigated as a basis for electrical resistance-based haemorrhage detection. The sensing principle relies on changes in the electrical resistance of the conductive network following liquid exposure, with the resulting resistance variation used as the sensing parameter. Nine conductive textile variants were developed and evaluated, comprising three knitted structures (K1–K3) and six woven structures produced in raw and finished states (W1–W3). The structures incorporated silver-coated polyamide and stainless-steel conductive yarns and were exposed to water, acidic perspiration (pH 5.5), alkaline perspiration (pH 8.0), and saline solution. Saline solution was used as a controlled conductive aqueous medium for comparison and does not reproduce the physical, chemical, rheological, cellular, or biochemical properties of whole blood. Electrical resistance measurements, together with physical and mechanical characterization, scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR), were performed to assess structural stability and electrical response. Saline solution produced the largest resistance variations among the tested liquids, whereas water and perspiration resulted in lower responses. Localized mechanical deformation further induced pronounced resistance changes in several woven structures. Among the evaluated variants, W2 exhibited the most favorable combination of structural stability and electrical responsiveness. These results support further investigation of W2 (conductive yarn: Filix DA5393 yarn) as an electrical resistance-based sensing structure for potential haemorrhage-related liquid detection applications. Full article

Severe soil salinization and low fertility significantly constrain sustainable agricultural development in the Yellow River Delta, one of the three major estuarine deltas in China. Despite their ecological importance, the regional-scale spatial interactions between soil salinity and nutrients, particularly regarding their vertical variability, remain poorly understood. This study analyzed 228 soil samples from 76 sites distributed across a distinct salinity gradient, which was determined by constructing a spatial salinity distribution map after sampling. Samples were collected at three depths (0–15, 15–30, and 30–45 cm) to investigate the spatial distribution of soil organic carbon (SOC), total nitrogen (TN), and the C/N ratio, along with their underlying driving factors. SOC and TN exhibited similar spatial patterns, with higher values distributed along both banks of the Yellow River. Horizontally, SOC and TN in the 0–15 cm layer decreased gradually from west to east, whereas the 15–30 cm and 30–45 cm layers showed an opposite trend, increasing eastward. Vertically, SOC and TN contents declined significantly with soil depth (p < 0.05), although the magnitude of this decline varied regionally: the 0–15 cm layer in the western area contained markedly higher nutrient levels than deeper layers, while vertical variation was less pronounced in the eastern and estuarine regions. Both variables were positively associated with total phosphorus (TP), available potassium (AK), soil moisture content (MC), clay content, and pH, but negatively correlated with electrical conductivity (EC), particularly in the 0–15 cm layer. Our results highlight that soil texture, moisture, and salinity affect the spatial heterogeneity and vertical decline of SOC and TN in the Yellow River Delta. Future research should focus on the long-term temporal distribution of the coupling of multiple elements under changing hydrological and salinity regimes. Full article

Accurate estimation of irrigation water use is essential for agricultural water accounting and water-resource allocation in large irrigated districts, yet existing statistics are usually available only as aggregated administrative totals and cannot adequately characterize seasonal and spatial differences in field-applied water. In this study, a soil moisture profile response-driven framework was developed to estimate spring and summer irrigation water use in the Hetao Irrigation District, a typical large-scale irrigated region in the upper Yellow River Basin. Soil property zones were first delineated using K-means clustering based on field capacity, wilting point, available water capacity, bulk density, porosity, and electrical conductivity, and season-specific soil profile response layers were identified through bootstrap stability tests using 0–100 cm daily soil moisture changes. A net water inflow response was then constructed by integrating soil water storage change, precipitation, and evapotranspiration, and six estimation models were compared, including a soil-water-response conversion model, historical-management baseline models, and recent-management baseline models. Model calibration was conducted for 2016–2021, and independent testing was performed for 2022. Spatial allocation constraints were further introduced to ensure consistency between total estimated irrigation volume and pixel-scale irrigation depth patterns. Results showed that the optimal soil profile stratification was 0–20/20–60/60–100 cm for spring irrigation and 0–20/20–50/50–100 cm for summer irrigation, indicating clear seasonal differences in profile response. For spring irrigation, the recent three-year management baseline model performed best, with a training-period RMSE of 8.8 mm and MAPE of 8.5%, and a testing-period RMSE of 8.4 mm, bias of −2.7%, and R² of 0.97. For summer irrigation, the historical-median management baseline model was most robust, with a training-period RMSE of 8.1 mm and MAPE of 14.0%, and a testing-period RMSE of 4.4 mm, bias of −9.4%, and R² of 0.96. Spatially, spring irrigation depths increased from 2019 to 2022 and were higher in WLBH, JFZ, and YJ, whereas summer irrigation depths were generally lower and more concentrated in western and central sub-irrigation districts. The proposed framework provides a practical approach for linking soil moisture profile response, management-based volume constraints, and spatially explicit irrigation mapping in large-scale irrigated regions. Full article

Alzheimer’s disease (AD), the leading cause of dementia, lacks an inexpensive and non-invasive method for early detection. Here, we investigate whether electrodermal activity (EDA), a measure of changes in electrical conductance at the skin’s surface, can offer a convenient avenue for AD screening by capturing the autonomic dysfunction associated with the disease’s pathology. As few studies have comprehensively examined EDA’s utility as a standalone biomarker for AD, we conducted a pilot study with 10 cognitively healthy controls and 20 patients with AD, evaluating EDA recordings collected during an orthostatic test and a Montreal Cognitive Assessment (MoCA). The AD group included both carriers from Colombian kindreds affected by autosomal-dominant AD and patients with sporadic late-onset AD. We compared EDA features between groups using statistical analysis and tested whether machine learning models could separate the two groups using these features. During the MoCA, phasic EDA measures, specifically the number of skin conductance responses (NSSCR) and mean time-variant sympathetic tone (TVSymp), were significantly lower in the AD group than in controls (NSSCR: $p=0.0083$, Cohen’s $d=-1.07$; mean TVSymp: $p=0.0166$, $d=-0.96$), suggesting a blunted sympathetic response to cognitive stress in AD. No significant between-group differences were observed during the orthostatic test (all $p\ge 0.60$). A random forest classifier trained on MoCA-derived EDA features achieved a balanced accuracy of 78% (95% CI 60 to 93%; 75% sensitivity, 80% specificity, AUROC 0.75), with phasic features contributing most to performance. Performance did not differ significantly from that of the support vector machine or logistic regression models. These results provide preliminary, hypothesis-generating evidence for the utility of EDA in screening for AD. The small sample size, unequal group allocation, sex imbalance, and substantial mean age disparity between groups (≈23.5 years) limit the strength of these conclusions and necessitate replication in larger, age- and sex-matched cohorts that include prodromal stages. Full article

Conductive polymer nanocomposites (CPC) are widely investigated as chemo-resistive materials for the detection of volatile organic compounds (VOC). However, the physical mechanisms governing their transient electrical response remain only partially understood, limiting the development of predictive models and highly selective sensors. In this work, the chemo-resistive behaviour of carbon nanoparticle-filled poly(ethylene-co-ethyl acrylate) (EEA-CNP) was investigated through a multiphysics experimental approach combining simultaneous measurements of solvent uptake, dimensional changes, temperature and electrical resistance during toluene sorption and desorption. Thick specimens were deliberately employed to amplify transient diffusion phenomena and enable direct observation of the coupling between mass transport, polymer swelling and conductive network evolution. The results demonstrate that electrical resistance cannot be interpreted solely from the average solvent concentration within the material. Instead, the transient response is primarily governed by solvent concentration gradients, which continuously modify the connectivity of the conductive nanoparticle network during diffusion. This mechanism explains the pronounced hysteresis observed between sorption and desorption, the transient resistance overshoot during sorption, and the absence of a unique relationship between resistance and solvent content under dynamic conditions. A dedicated quasi-static desorption protocol was therefore developed to minimise concentration gradients and establish the intrinsic correlation between electrical resistivity and solvent fraction. The experiments further show that a solvent content of approximately 6 wt% is sufficient to completely disrupt the conductive percolation network. These findings provide new insights into the multiphysics mechanisms governing chemo-resistive sensing and establish an experimental basis for the development and validation of predictive models for conductive polymer nanocomposites. The proposed methodology is expected to contribute to the optimisation of next-generation VOC sensors and electronic noses with improved selectivity and predictive capability. Full article

We propose and demonstrate, for the first time, a sandwich structure of graphene substrates, pyrene derivatives, and an electrolyte for ultraviolet light sensing. A contact capacitor forms at the graphene–electrolyte interface via the electric double layer. When ultraviolet light excites the interlayer of the pyrene derivative, a photo-generated electric field changes the carrier density in graphene, affecting its conductivity. Thus, the sandwich structure responds to ultraviolet light intensity, which is monitored by current changes in different states. Linear fitting shows a strong positive relationship between UV intensity and current (Ids), with R² above 0.99 and excellent reproducibility. The responsivity (R) and response time (τ_r) for the measurement at a distance of 50 cm are estimated as 0.7 A/W and 70 s, respectively. Full article

Quasi-vertical (QV) GaN Schottky barrier diodes (SBDs) have emerged as a promising device architecture that overcomes the limitations of conventional lateral and vertical SBDs while offering high electrical performance. However, the influence of the lateral and vertical current-transport dimensions on the electrical characteristics of QV GaN SBDs has not been systematically evaluated. In this study, the effects of the anode-to-drift length (L_AD), drift-to-cathode length (L_DC), and drift-layer thickness (DLT) on the DC and RF characteristics were systematically investigated. Variations in L_AD and L_DC produced relatively modest changes in the forward conduction characteristics, with the current density decreasing by up to 15% and the specific on-resistance (R_ON,SP) increasing by up to 29%, while the breakdown voltage (BV) varied by less than 4%. Increasing the DLT from 0.5 to 4 μm produced substantially larger variations, reducing the current density by 62% from 11.38 to 4.28 kA/cm² and increasing R_ON,SP by 171% from 0.17 to 0.46 mΩ·cm², while BV increased from 55 to 199 V. The stronger dependence on DLT, particularly in reverse blocking capability, identifies DLT as the dominant geometrical parameter governing the DC characteristics. RF characterization as a function of DLT showed that the series resistance (R_s) strongly depended on DLT, whereas the junction capacitance (C_j) exhibited comparatively moderate variation. The DLT = 0.5 μm device exhibited the highest estimated RC cutoff frequency (f_c) of 18.2 GHz, whereas the DLT = 1 μm device maintained a relatively high f_c of 15.3 GHz while providing a more balanced DC and RF performance. The device with L_AD/L_DC = 7/5 μm and DLT = 1 μm exhibited R_ON,SP = 0.21 mΩ·cm², turn-on voltage (V_ON) = 0.54 V, and BV = 128 V. These findings provide practical guidelines for the dimensional design of QV GaN SBDs for microwave rectifier applications. Full article

The transition to sustainable energy is critical for addressing global climate change. Hydrogen production, particularly via electrolysis, has emerged as a key solution, offering the potential for low-carbon energy across various sectors. This paper conducts a spatiotemporal life cycle analysis of electrolytic hydrogen production in Australia under time-varying CO₂ management schemes. Three scenarios are studied. The baseline scenario studies hydrogen production at a fixed rate of 20 kg/h, resulting in monthly carbon emissions of 30–500 metric tons of CO₂, depending on the Australian state and chosen month. Variable production scenario 1 reduces hydrogen production in a tiered fashion as the grid’s carbon intensity increases, resulting in monthly carbon emissions of 30–110 metric tons of CO₂, depending on the Australian state and chosen month. Finally, variable production scenario 2 restricts hydrogen production to periods when the life cycle carbon intensity (LCA CO₂eq) of electricity falls below a predefined threshold of 0.6 kg CO₂ per kg H₂, thereby qualifying for hydrogen tax credits and resulting in monthly carbon emissions of 0.1–0.6 metric tons of CO₂ in Tasmania. Leveraging real-time data from the Electricity Mapping database and real-time electricity cost data from the AEMO database, the three scenarios study the effect of dynamically adjusting hydrogen output to reduce both emissions and production costs. Furthermore, the integration of hydrogen tax credits significantly enhances cost-effectiveness, offering a viable pathway for widespread adoption. This study concludes that dynamic, real-time operation, coupled with financial incentives, offers a promising approach to enhancing the sustainability and economic viability of hydrogen production. Full article

Microplastics are emerging as ubiquitous contaminants in agricultural soils, while nickel (Ni), although catalogued as a potentially toxic element, is an essential micronutrient and a cofactor of urease. In a pot experiment, this study examined how three microplastics (polyethylene, PE; poly(ethylene terephthalate), PET; and polystyrene, PS) affect nickel availability and the properties of two calcareous agricultural soils from central Greece. The microplastics were applied at two levels (1.5 and 3.0% by weight), and the samples were analysed at four time points (3, 6, 9, and 12 months, n = 3). Total (aqua regia) and available (DTPA) nickel, pH, electrical conductivity, organic matter, bulk density (BD), water-holding capacity (WHC), and microbial respiration (qCO₂) were measured, and the data were evaluated by one-way ANOVA with Tukey HSD tests. Total nickel remained stable (about 15.1–15.4 mg/kg; non-significant), whereas the available fraction changed systematically. In Soil 1 (12 months, 1.5%), PE raised DTPA-Ni by +24.9%, PET by +19.8% and PS by −1.7%, while at 3.0% the increases reached +39.8% and +31.7%. In parallel, PE lowered bulk density by up to −16.1%, PET raised water holding capacity by up to +28.9%, and PS raised microbial respiration by up to +38.3%, producing distinct, polymer-specific responses. The changes intensified with time and dose and were milder in the more strongly buffered Soil 2. Microplastics redistribute the biologically active, rather than the total, pool of nickel, a finding that supports reappraising Ni as a nutritional micronutrient and monitoring its available fraction. Because no plants were grown, the nutritional interpretation is advanced as a hypothesis for future testing rather than as a demonstrated agronomic benefit, and the applied microplastic doses (1.5–3.0% w/w) exceed most reported field levels and were chosen to resolve mechanisms under accelerated conditions. Full article

Fish farming can contribute to sustainable rural tourism when environmental performance and visitor expectations are considered jointly. This study aimed to evaluate fish farming as a strategy for sustainable tourism in Somondoco, Boyacá, Colombia, by integrating an environmental assessment of water quality with visitors’ perceptions of sustainable tourism. A case study was conducted at the “Los Lagos” fish farm, where physicochemical parameters were measured at the water supply and discharge points and the water quality index (WQI) was calculated. In parallel, a survey of 73 visitors was conducted to characterize perceptions of sustainable tourism and willingness to pay for more sustainable services. The WQI decreased from 0.75 (acceptable) at the water supply point to 0.60 (regular) at the discharge point, mainly associated with changes in electrical conductivity and chemical oxygen demand. From the tourism perspective, 93.1% of respondents considered sustainable tourism important, while 54.8% identified responsible management of natural resources as the main aspect to be addressed. In addition, 84.9% expressed willingness to pay an additional 10–20% for a more sustainable offering. The integration of environmental and tourism-perception results, complemented by a SWOT analysis, identified water management, environmental education, technological modernization, and community participation as priority areas for sustainable tourism development. These findings provide a case-based framework for linking aquaculture environmental performance with visitor expectations in the formulation of sustainable tourism strategies. Full article

Agricultural biomass fly ash (BFA) has attracted increasing interest as a liming material and nutrient source for acidic soils, although its effects on trace element availability and plant accumulation remain insufficiently understood. This study characterized agricultural BFA and evaluated its short-term effects on soil chemical properties, nutrient and trace element availability, and trace element concentrations in maize biomass. Unlike previous studies focusing primarily on biomass ash characterization or crop performance, this study integrates biomass fly ash characterization with post-harvest soil properties, nutrient and trace element availability, and trace element accumulation in maize biomass. A 60-day greenhouse pot experiment was conducted in an acidic loamy sand using BFA and commercial agricultural lime (CAL) applied at rates corresponding to 0.5×, 1.0×, and 1.5× soil hydrolytic acidity. Both amendments increased soil pH, reduced hydrolytic acidity, and increased base saturation, although CAL produced a stronger liming effect. BFA supplied substantially more K and Mg and increased soil total carbon and electrical conductivity, while CAL was more effective in increasing Ca availability. Changes in soil trace element availability were generally limited, although Zn and Cr increased after BFA application. Trace element responses in maize biomass were element-specific: concentrations of Fe, Cu, Co, and Cd increased, Mn decreased, and Zn and Ni showed no consistent dose-dependent pattern. Nevertheless, the concentrations measured in maize remained within ranges commonly reported for plants grown on uncontaminated soils. PCA supported the contrasting effects of the amendments, associating BFA more strongly with nutrient availability, total carbon, and electrical conductivity and CAL with soil deacidification and Ca enrichment. Under the conditions of this short-term pot experiment, agricultural BFA improved selected chemical properties of acidic soil without causing pronounced increases in trace element accumulation in maize biomass. Field-scale and long-term studies, including chromium speciation, are required before broader agricultural application can be recommended. Full article

High-solar-reflectivity cladding materials are widely promoted to reduce cooling demand and mitigate urban heat island effects. However, in cold and mixed climates, their overall energy and carbon performance remains uncertain due to potential winter heating penalties and embodied carbon trade-offs. This study presents a comparative evaluation of energy use, annual operational carbon emissions, and material-level embodied carbon for high-reflectivity cladding applied to commercial buildings across representative Canadian climate zones. Dynamic simulations were conducted in EnergyPlus using a standardized warehouse archetype in Montreal, Toronto, and Vancouver, representing cold continental, mixed continental, and marine climates. Roof and wall solar reflectivity (albedo) was varied from 0.2 (baseline) to 0.8 (high reflectivity), while other envelope properties remained constant. Increasing reflectivity reduced annual cooling demand by approximately 15% in Montreal and Toronto and 20% in Vancouver, with the largest reductions during peak summer periods. However, reduced winter solar heat gains produced heating penalties, increasing total annual energy use by 1% in Montreal, 0.5% in Toronto, and less than 0.5% in Vancouver. Operational greenhouse gas emissions were calculated by converting simulated annual electricity and natural gas use into CO₂-equivalent emissions using provincial grid emission factors and combustion factors consistent with Environment and Climate Change Canada reporting. The results demonstrate the strong influence of regional energy supply on operational carbon outcomes. A cradle-to-gate (A1–A3) life cycle assessment quantified embodied carbon of representative cladding materials using Environmental Product Declarations and North American databases. Embodied carbon varied considerably: product-specific steel cladding manufactured in low-carbon electricity regions showed global warming potential as low as 1.76 kg CO₂e/kg, compared with industry averages exceeding 2.4 kg CO₂e/kg. Rather than performing a complete whole-life carbon assessment, this study comparatively evaluates annual operational carbon emissions and material-level embodied carbon to improve understanding of the energy and carbon implications of high-solar-reflectivity cladding materials in representative Canadian climates. The results demonstrate that climate conditions, envelope thermal performance, regional energy supply, and manufacturing pathways influence the environmental performance of cool envelope strategies. Full article