Electrical Conductivity Values Research Articles

Giant Seebeck coefficient in SnTe thin films grown by thermal evaporation using layered structure engineering

In this work, we have reported a giant Seebeck coefficient (8033 µV/K) in SnTe thin films by controlling the layered structure using post growth annealing technique. The samples used in the current study were synthesized using a vacuum tube furnace having an evaporation temperature 700 °C, base pressure 180 m Torr and source to substrate distance 7 cm. Sn and Te metal powders with an equal weight ratio were evaporated on the glass substrate to form SnTe composite. Post-growth annealing in vacuum environment was performed for different time’s duration of 1–4 h with a step of one hour. XRD analysis reveals six diffraction peaks for all samples, which correspond to different crystal planes of SnTe structure. Raman spectra exhibit the presence of specific vibrational modes associated with SnTe. Using the giant value of Seebeck coefficient and moderate electrical conductivity, a strong power factor value of 8.1 × 10−3 W m−1 K−2 was observed for optimized sample (annealed for 3 h). The strongest values of Seebeck coefficient and power factor are supposed to be the layered structure of SnTe thin films which was verified by the SEM images.

Characterization of physical and chemical properties of honey from Northeastern Anatolia of Türkiye

The aim of this study was to investigate the physical and chemical properties of natural highland honey produced in the northeastern Anatolia region of Turkey. In 2020, 24 honey samples collected and sold during the honey harvest season were purchased from local vendors. Moisture, color, acidity, pH, conductivity, diastase and invertase activity, C13, C13 protein-honey, C4 analysis and sugar components were analyzed in honey samples. The honey samples were found to contain 17.4% moisture. The mean invertase level were found to be 156.216 U/kg. The freshness and enzymatic activity of the honey were shown by the average diastase number of 12.8 DS. The mineral content and overall purity of the honey was indicated by an electrical conductivity value of 0.17 mS/cm. The average acidity value 15.9 meq/kg, fructose/glucose ratio 1.26% and the average color value 33 mm Pfund determined. The average sugar contents in the honey samples were as follows: fructose 37.4%, glucose 29.5%, sucrose 1.4%, turanose 1.8%, maltose 0.6%, isomaltose 0.2%, erlose 0.3%, trehalose 0% hybriditose 0% maltotriose 0% fructose+glucose. 66.9%, fructose/glucose 1.26, glucose/water 2.0. The mean difference between honey protein and honey delta C13 data is -0.58 and C4 sugar ratio is 0. In conclusion, valuable findings were obtained on the physical and chemical properties of honey from the northeastern Anatolia region of Turkey. Further research can build on these findings to explore the unique properties and potential benefits of honey from this region and contribute to its value and utilization in various industries.

Modification of Hilhorst model for saturated extract electrical conductivity estimation of coir using frequency domain reflectometry sensors – A laboratory study

Frequency domain reflectometry (FDR) sensors can measure moisture content and electrical conductivity (EC) of growing media, thus providing information for effective water and nutrient management of crops. FDR sensors generally provide the bulk EC (σb) value, which is different from the saturated extract EC (σe) values that most growers and practical studies generally use. To properly estimate σe of media, we modified the previous Hilhorst model that calculates pore water EC (σp) from FDR sensor readings. The 16 coir samples with four moisture and four EC levels were prepared, and their changes in the dielectric constant of bulk medium (εb), σb, and medium temperature from the FDR sensors were recorded and used for analysis. As a result, the εσb=0 (εb when σb is 0) of the coir used in this experiment was 1.64, which was much lower than the εσb=0 suggested for mineral soil (4.1), indicating that the medium-specific εσb=0 should be adjusted. Although σe value estimation through the Hilhorst model with adjusted εσb=0 improved, the values were still unreliable to represent the actual σe values (root mean square error, RMSE = 2.280, R2 = 0.30). To convert the σp derived from the Hilhorst model with adjusted εσb=0 to actual σe, the regression equation was applied as σe = 0.5381 × σp + 1.6493. The adjusted Hilhorst model could provide a more reliable σe estimation (RMSE = 0.929, R2 = 0.62). These results indicate that proper adjustment of εσb=0 for the specific medium is necessary, and adjusting the equation for converting σp into σe would be helpful to properly interpret the σb to practically utilize the FDR sensors for effective water and nutrient management.

Pengembangan roti berbahan pati jagung dengan modifikasi enzimatis & pemanas ohmik (Kajian: pengaruh variasi tegangan dan transglutaminase terhadap karakteristik produk) [Development of corn starch-based bread with enzymatic modification & ohmic heating: study effect of voltage and transglutaminase variations on product characteristics

The main challenges in producing gluten-free bread are closely related to its development, texture, and nutrition. This research consisted of 2 stages. Stage 1 was aimed to determine the effect of voltage variations (70 V, 80 V, 90 V, 100 V, 110 V, 120 V, and conventional baking as a control) on bread characteristics and process parameters. The experiment was arranged as non-factorial in a completely randomized design with 3 replications. The best results of the first stage were applied in stage 2, aimed to determine the effect of various concentrations of TGase (0, 0.5, 1, 1.5, 2, and 2.5%). The data were processed using analysis of variance, then further tested using Tukey's at the 5% level. The 120 V voltage gradient treatment was found to be the best treatment. It shows specific volume 3.17±0.17 cm3/g, baking loss 14.58±1.50%, brightness 50.97±3.27, hardness 3.76±0.11, cohesive 0.34±0.03, pore density 84±2.52. In addition, baking at a higher voltage level increased the temperature rate and electrical conductivity. The 120 V voltage treatment shows the time required to reach a maximum temperature of 97°C was 3 minutes 5 seconds, and an electrical conductivity value of 0.26-0.51 S/m. Based on the TGase treatment, it was found that when bread dough was applied with a higher TGase concentration, the specific volume, hardness, chewiness, resilience, cohesiveness and springiness, average pore size, and pore porosity of the bread increased.

Mamdani-type fuzzy inference system for irrigational water quality

This paper aims to evaluate the quality of groundwater resources used for irrigation purposes using a Mamdani-type fuzzy inference system (MFIS). The MFIS is used to resolve ambiguities and uncertainties in economic, social, and natural systems and also facilitates the capture of expert knowledge in ways similar to human reasoning and thought processes. In this study, 20 groundwater samples were collected from various locations within the Mayiladuthurai district, Tamil Nadu, India, between January 2016 and December 2019. These samples underwent physical and chemical analyses to assess the suitability of the collected water resources for irrigation. The analysis utilizes the Mamdani Fuzzy Inference System, which combines values of Electrical Conductivity (EC) and Sodium Adsorption Ratio (SAR). Additionally, methods from the US Salinity Laboratory Staff were also employed. Ultimately, the groundwater quality in Mayiladuthurai is graded for irrigation use by this method. The results indicate that the MFIS reduces imprecision and uncertainty in data handling through the fuzzy membership function. The comparison of irrigation suitability results clearly demonstrates that the proposed MFIS method offers an improved assessment of the irrigation water quality level of the studied groundwater resources.

Crystallographic texture evolution in hot-press sintered tungsten heavy alloy with the effect of niobium (Nb) addition

This study examines the impact of niobium on the crystallographic texture evolution and grain boundary distribution of hot press sintered tungsten heavy alloy (W-4.9Ni-2.1Cu). EBSD analysis was used to examine the evolution of crystallographic texture and grain boundary character distribution in sintered compacts. The important findings of this study depict that cubic texture component {001} <111> were evolved in niobium unalloyed compacts due to the solidification of atoms aligned in a specified preferred orientation. Besides, it reveals the weakness in the cubic texture in niobium alloyed compacts due to the recrystallization followed by sub structural recovery occurrence during sintering. In addition, an increase in CSL fraction in niobium alloyed compacts illustrates the dominance of surface diffusion during sintering caused by the grain refinement attributed from the niobium enrichment at the tungsten-binder interface. Metallographic studies showed that the niobium concentration increment in WHAs has concomitant effect with sintered compacts' properties. A W-4.9Ni-2.1Cu-1 Nb alloy achieved the highest values for micro-hardness (432 HV0.5), electrical conductivity (23.74 % of IACS), and relative density (99.90 %).

Geochemical and Isotopic Characteristics of the Emir Geothermal Waters in Kula Area, Western Anatolia

In this study, we investigate chemical and isotopic characteristics of thermal waters of the Emir geothermal field in the Kula region, which hosts the youngest volcanism in Turkey. Studied thermal waters with temperature and electrical conductivity values of 21–63 °C and 3840 to 5210 μS/cm are of Na–HCO3 type and have neutral character. δ18O and δD of thermal waters are − 9.40 to − 8.41‰ and − 64.16 to − 56.38‰ (VSMOW) and indicate a meteoric source with local recharge. Tritium values of thermal waters in the Emir geothermal field are mostly < 1 TU signifying a deep circulation. Positive δ13C values (1.32–4.46‰ VPDB) imply that carbon is derived dominantly from marine limestone and dominantly from endogenic CO2. δ18O and δ34S of dissolved sulfate yield that marine limestone is the source of sulfur in thermal waters, which are partly affected by sulfide oxidation and bacterial reduction processes. At discharge temperatures, Emir thermal waters are oversaturated with respect to albite, aragonite, calcite, α-cristobalite, dolomite, gibbsite, illite, K-feldspar, kaolinite, muscovite and quartz but undersaturated for anhydrite and wairakite. The activity diagrams suggest that high Na+ and K+ concentrations in waters are attributed to dissolution of muscovite, K-feldspar and albite. Chemical and isotopic compositions of the Emir thermal waters are controlled by a combination of processes including water–rock interaction, dissolution/precipitation and ion exchange. Various chemical and isotopic geothermometers applied to the thermal waters yielded reservoir temperatures in the range of 80–125 °C. Paleo-temperatures estimated from δ18O values of travertines and thermal waters (isotope fractionation) are consistent with modern discharge temperatures.

A Comparative Study on the Influence of N‐Doped Primary and Secondary Hydrochars on the Electrochemical Performance of Biobased Carbon Electrodes for Energy Storage Application

AbstractThe hydrothermal carbonization (HTC) technique and subsequent pyrolysis were applied. Herein, two different types of biobased feedstocks, sucrose (Suc) and Miscanthus (Mis), were chosen. Urea served as N precursor for the in situ doping. HTC of Suc and Mis with urea leads to N‐doped hydrochars (N‐HCs). Suc and Mis decompose in different, complex degradation pathways, which leads to the emergence of N‐HCs consisting of distinct ratios of N‐containing primary chars (N‐PCs) and secondary chars (N‐SCs). After pyrolysis, maximum N contents of 5.6 wt % and 4.8 wt % of the N‐doped pyrolyzed hydrochar (N‐PHC) electrodes from Suc and Mis, respectively were reached. The role of PC and SC formation on the impact of N‐doping in the context of physicochemical properties of the N‐PHCs was compared with each other. In this study, they were tested with respect to the influence of N‐PCs and N‐SCs on their electrochemical performance in energy storage application. It turned out that the electrical conductivity (EC) and specific capacitances increased. Highest EC value of 129.1 S ⋅ cm−1 was obtained with N‐PHC based on Suc. Simultaneously, enhanced average specific capacitances of 47.0 F ⋅ g−1 at 5 mV ⋅ s−1 and 3.5 F ⋅ g−1 at 100 mV ⋅ s−1 are ascertained with N‐PHCs from Suc and Mis, respectively.

Optimization of an innovative hybrid approach ZnO-Doped PVP nanofibers for electrical devices applications

The solid solution of pure ZnO nanoparticles and doped Polyvinylepyrrolidone (PVP) green hybrid nanomaterial’s synthesized by using the electro spinning method. The synthetic polymer matrix nonwoven fibrous mats containing innovative properties are shown to shrink and encapsulated the zinc oxide materials to change the surface morphology when the concentration of PVP is increased from 1 % to 2 % dopants. The crystalline nature and morphological studies were examined by using x-ray diffraction and a scanning electron microscope. The average crystallite sizes of easily formed ZnO nanoparticles and nanorods that are 21 nm and 62 nm respectively. Moreover, the electrical and optical properties of the fibrous mesh were determined by using electrical impedance analyzer. The electrical conductivity values were measured in the pure ZnO nanoparticles in contrast to the doped ZnO/PVP. The tangent loss, dielectric constant, capacitance and relaxation time values are revealed in this study. All the characterization has been carried out at room temperature. The relaxation time for 1 %, and 2 % ZnO/PVP is (0.8 ns) and (0.79 ns) respectively which is suitable for the application of trigger using devices. The overall findings of this study implemented in a wide range of technologies i.e. photonics, electronics and super capacitor devices etc.

Performance of vertical flow constructed wetland for the treatment of effluent from a brassware industry in city of Fez, Morocco: a laboratory scale study

Brassware industry constitutes the second most polluting industrial sector in Fez city, Morocco, owing to its high heavy metal load. The aim of this study is to examine and evaluate the performance of vertical flow constructed wetlands in treating brassware effluents using various plant species. Ten treatment systems were planted with four types of plants: Chrysopogon zizanioides, Typha latifolia, Phragmites australis, and Vitex agnus-castus, while another system remained unplanted. These systems underwent evaluation by measuring various parameters, including pH, electrical conductivity, suspended solids, chemical oxygen demand, biological oxygen demand, sulfates, orthophosphates, total Kjeldhal nitrogen, ammonium, nitrates, nitrites, and heavy metals such as silver, copper, and nickel, using standard methods over of ten weeks. The results obtained demonstrate effectiveness of these systems. When planted with Ch. zizanioides, the systems achieved elimination rates of 83.64%, 98.55%, 91.48%, 86.82%, 80.31%, 96.54%, 98%, and 98.82% for suspended solids, ammonium, nitrites, BOD5, sulfates, orthophosphates, silver, and nickel, respectively. System with V. agnus-castus showed significant reductions in nitrate and copper, with rates of 84.48% and 99.10%, respectively. Considerable decrease in pH and electrical conductivity values was observed in all systems, with a notable difference between planted and control systems regarding effectiveness of treatment for other parameters.

PAN-based fiber-reinforced carbon-carbon composites for improved fire retardancy and thermal and electrical conductivities for harsh environments

Carbon-carbon (C-C) fiber composites are a new class of materials that are used in various industries due to their exceptional chemical, thermal and electrical conductivities properties. In this study, carbon-carbon fiber composites were manufactured where polyacrylonitrile (PAN) powder was dissolved in dimethylformamide (DMF) solution, and carbon fibers with desired concentrations (20–80 wt%) were immersed into this solution as reinforcement through evaporation and solidification. The PAN-fiber systems were then stabilized at 250–270°C for 120 min in the air and subsequently carbonized at 650, 750, and 850°C for 60 min in the presence of argon gas to obtain the desired C-C fiber composites. Thermogravimetric analysis (TGA) results showed that the carbonized samples had a small weight loss of 2.5%, while actual and oxidized samples had more weight loss. Moreover, the carbonized sample surface was more hydrophobic compared to other samples due to the carbon presence and surface texture changes. Fourier-Transform Infrared (FTIR) spectroscopy peaks showed the presence of different functional groups of PAN before oxidation and carbonization, but those peaks disappeared after oxidation and carbonization. The developed carbon-carbon composite passed the UL94 vertical flame retardancy testing with a V-0 rating. Surface smoothness, proper matrix and reinforcements bonding were confirmed by scanning electron microscopy (SEM) results and the manufactured composite properties changes were validated by the confocal microscopy images. The carbon-carbon fiber composite achieved an electrical conductivity value up to 4.75 × 103 S/m after the carbonization process. The excellent thermal, chemical, and electrical properties of these composites can be useful for numerous industrial applications in different extreme environments.

Assessment of Reclaimed Mined Area of Sahastradhara, Dehradun by Soil and Vegetation Analysis

This study investigates the impact of forest area mining on reclaimed limestone mined areas in Sahastradhara, Uttarakhand, India. Initiated in 1989-90, eco-restoration efforts aimed at rehabilitating the mined areas resulted in restoration ages of 25, 24, and 23 years across different sites. The study comprehensively examined vegetation and soil physicochemical properties at various depths, revealing the dominance of species like Murrayakoenigii, Acacia catechu, Vitex negundo, Eupatorium adenophorum, Grevillea robusta, and Lantana camara. Soil analyses unveiled variations in moisture content, bulk density, and coarse fragment percentage across the sites, a rise in organic carbon, phosphorous, and nitrogen levels, showcasing soil improvement post-restoration. Correlation analyses unveiled interrelationships between soil properties, emphasizing the importance of organic matter in influencing soil acidity. Vegetation analyses at different sites revealed evolving plant communities, with prominent species contributing to the ecological richness. The Importance Value Index (IVI) and Shannon Weiner Index (H') provided insights into species dominance and biodiversity. The results showed that the soil pH was slightly basic, and the available phosphorus and nitrogen levels were within the optimal range for plant growth. However, the bulk density and electrical conductivity values were higher than the recommended range. This study contributes valuable insights into the intricate interplay between mining activities, vegetation dynamics, and soil health, guiding future ecological restoration endeavors in similar contexts. The study concluded that the eco-restoration work carried out in the area has been successful in restoring the vegetation, but further assessment is required to ensure the long-term success of the restoration efforts.

Delineation of Groundwater Potential Zones for Sustainable Development and Planning using AHP and GIS Techniques in the Coal Mining Province of Mahan River Catchment Area

The present research aims to address the drinking water crisis in the Mahan River catchment area resulting from the disruption of groundwater availability due to extensive coal mining. The study uses GIS-based Multi-Criteria Decision Analysis (MCDA) to map the groundwater potential of the area by analysing several factors that affect groundwater availability, including rainfall, water depth, geomorphology, geology, soil, land-cover/land-use, and topographic characteristics derived from DEM. The groundwater potential map created using the MCDA technique classified the area into low, moderate, and high groundwater potential zones. The map was validated and verified using water table depth and electrical conductivity values available in the region, indicating that it can be used to identify groundwater recharging sites. The study’s results show that about 30% of the area has high groundwater potential, and more than 45% of the area has moderate groundwater potential. The information derived from the study can be used for sustainable management and proper planning of groundwater resources in the Mahan River catchment area. Overall, the study presents a useful approach to address the groundwater depletion problem resulting from coal mining activities in the Mahan River catchment area.

Bacterial Contamination of Drinking Wells in Makurdi Metropolis

This study was carried out to assess the bacterial contamination of drinking wells in Makurdi metropolis. Fifteen (15) untreated water samples, five (5) each were collected from wells in High Level, Wurukum and Wadata areas for physicochemical and bacteriological analysis was done using pour plating and the bacteriological quality was assessed by measuring the total viable, total coliform and fecal coliform counts of bacteria in the samples using Mac Conkey agar and Nutrient agar. The results of the analysis showed that the pH ranged from 6.70 ± 0.16 to 7.40± 0.87, the temperature levels ranged from 28.72 ± 0.04 to 28.87 ±0.05; biological oxygen demand values ranged from 0.02 ±0.04 to 0.02 ± 0.41; the dissolved oxygen values ranged from 1.50 ±0.16 to 170 ± 0.14 while the Electrical conductivity values ranged from 599.20 ±88.98 to 1582.80±199. The results also showed the total viable count, total coliform count and fecal coliform counts ranging from 75.80±16.01cfu/ml to 117.40±34.45cfu/ml; 5.60±5.13cfu/ml to 6.60±6.88cfu/ml and 0.40±0.89cfu/ml to 4.20±3.77cfu/ml respectively. The total viable counts ranged from 75.80±16.01 to 117.40±34.4 (Wadata having the highest and Wurukum having the least), the total coliform counts ranged from 5.60±2.61 to 6.60±6.88 while the fecal coliform count ranged from 0.40±0.89 to 4.20±3.77. The variation in Total Viable Count (TVC) across locations could be as a result of localized factors influencing microbial populations and geographical differences such as land use, anthropogenic activities, and environmental conditions. The bacterial isolates were Bacillus, Escherichia coli, Klebsiella spp, Proteus spp, Enterobacter spp, and Staphylococcus spp. The frequency of occurrence and prevalence percentages of the bacteria isolated from the well water samples show that Klebsiella spp had the highest percentage (23.33%) while Enterobacter spp and Escherichia coli had the least prevalence percentage, representing 10.00% each. Overall, High Level had the highest contamination rate, accounting for 43.33% of the total contamination while Wurukum had the least contamination, representing 23.33% of the total contamination. The distribution patterns of bacterial isolates among the studied locations illuminate discernible trends. The prevalence of pathogenic bacteria in well water sources could be possibly linked to higher urbanization and population density, highlighting the dynamic and site-specific nature of microbial communities. The study highlights the importance of using specific plans to manage water quality. These plans should take into account the special features of each area.

Isoflavone profile and soybean quality: Effects of genotype, cultivation environment and storage

The interaction between soybean genotypes and environmental conditions alters the chemical and phytochemical composition of soybeans. These changes influence the quality of soybeans during storage. Therefore, the study analyzed the influence of soybean genotypes (BMX ALVO RR, DM 57I52RSF IPRO, BRS 5601 RR, and 95r51), cultivation environment (Bagé, Cachoeira do Sul, Vacaria, and São Luiz Gonzaga), and storage time (0, 6, 12 months) on quality parameters and the isoflavone profile of soybeans. The analyses performed included titratable acidity, soluble protein, germination, electrical conductivity, soybean defects, colorimetric profile, and isoflavone profile. The Vacaria environment showed the lowest values for acidity (0.86–0.91%), lipase activity (6.14–14.2%), electrical conductivity (194.5–335.0 μS/cm), and fermented grains (0.45–1.4%) at the end of storage, regardless of the analyzed genotype, demonstrating to be a suitable environment for the cultivation of these genotypes. Additionally, the highest concentrations of isoflavones were also detected in the genotypes cultivated in Vacaria at the beginning of storage (2205.0–2983.8 μmol/g). Analyzing all the results, the 57i52RSF genotype cultivated in Vacaria showed the best quality during storage. On the other hand, the 95r51 genotype exhibited low quality during storage, especially when cultivated in São Luiz Gonzaga.

Evaluation of Different Soil Salinity Indices Using Remote Sensing Techniques in Siwa Oasis, Egypt

Detecting and monitoring changes in soil salinity through remote sensing provides an opportunity for field assessment in regions where on-site measurements are limited. This research, conducted in Siwa Oasis, Egypt, aimed to assess the effectiveness of remote sensing techniques in detecting and monitoring changes in soil salinity. Using Landsat 5 and Landsat 7 satellite images, the researchers evaluated various soil salinity indices based on 56 on-site ground measurements. The study aimed to improve the correlation between electrical conductivity (EC) and index values and explore the relationship between salinity and changes in land cover. Eleven spectral indices were calculated for nine scenes captured in different months. Different approaches were employed, including stacking the data, categorizing EC measurements into salinity levels, analyzing data temporally, and conducting spatial correlation analysis. The initial approach revealed a weak correlation, due to substantial variation in EC values. However, the salinity index SI demonstrated the highest correlation coefficient of 0.38. In the second scenario, the salinity index 2 S2 index exhibited the highest correlation of 0.96 for moderate salinity samples. The third scenario showed that the salinity index 1S1 achieved the highest correlation value of 0.99 for moderately saline areas. In the fourth scenario, the SI index exhibited the strongest correlation among all four ponds, with correlation coefficients of 0.23, 0.23, 0.18, and 0.61. Notably, the correlations observed in the second and third scenarios demonstrated higher correlation coefficients than those of both the first and fourth scenarios. Additionally, remote sensing methods detected a 48% increase in total vegetated area over 17 years, showing the potential of remote sensing techniques in salinity monitoring for expanding agriculture and improving land management.

AUTOMATED CONTROL OFTHE THIN FILMS ELECTRICALCONDUCTIVITY BY THE EDDY CURRENT METHOD

The article considers the possibility of using the eddy current method of non-destructive testing for the problems of measuring the electrical conductivity of thin metal films. As the object of measurement, we used copper films of various thicknesses obtained by vacuum vapor deposition. A review of current trends in the use of copper films in modern industry and science is presented, and an analysis is made of current methods of non-destructive testing suitable for studying thin copper films. A brief description of the deposition method and the hardware-software complex for measuring the electrical conductivity of the film is presented. A calibration curve is presented, which makes it possible to restore the values of the electrical conductivity of the film from the value of the signal of the eddy current transducer. GaAs samples were selected to construct a calibration curve. The decision is explained by the proximity of the values of the electrical conductivity of this chemical compound to the calculated indicators of the obtained thin films. The results of testing films with different characteristics are presented and the distribution of the electrical conductivity of the films depending on the batch is shown. A series of practical measurements of thin films demonstrated the existence of a relationship between the mass of the initial substance that was subjected to deposition and the characteristics of the resulting films. According to different values of electrical conductivity within the same batch, it was concluded that there is a difference in the quality of deposition of different films.

Gel-Embedded Biochar and Hydroxyapatite Composite for the Improvement of Saline-Alkali Soil and Plant Growth Promotion.

Soil amendments play a crucial role in modern agriculture, as they effectively enhance the planting environment. This study innovatively proposes the use of gel as a crosslinking agent to embed biochar and hydroxyapatite (HAP), thereby preparing a novel soil amendment. Furthermore, this study investigates the soil improvement effects of this amendment as well as its influence on plant growth. This study employed a hydrothermal method to combine corn stalk (CB) or sludge (SB) biochar with HAP at different ratios (0-20%). Subsequently, sodium alginate gel (SA) was utilized to encapsulate the biochar and minerals, successfully forming a ternary composite gel material (corn stalk biochar/sludge biochar-sodium alginate gel-hydroxyapatite: CB/SB-SA-HAP). Finally, the practical effectiveness of this amendment was verified through potted soil experiments. The results indicate that the CB/SB-SA-HAP composite materials exhibited a micrometre-scale spherical structure with well-developed micropores and possess the functional groups of CB/SB, SA, and HAP, along with unique mineral properties. Through pot experiments, it was verified that the composite material effectively enhances multiple soil properties. After 21 days of cultivation, the soil pH values stabilized within the neutral range (pH = 7 ± 0.3) across all treatment groups. Except for the CB0 (CB:HAP = 1:0) and CB2.0 (CB:HAP = 1:2) treatments, the remaining treatments significantly reduced the soil EC values by 3.27% to 47.92%. All treatments significantly increased the contents of alkali-hydrolysable nitrogen (AHN) (34.89~57.91%), available phosphorus (AP) (35.93~56.55%), and available potassium (AK) (36.41~56.80%) in the soil. In comparison, although the SB treatment was more effective in regulating the pH and electrical conductivity (EC) of saline-alkali soil than the CB treatment, it was less effective in promoting plant growth in the short term. Through correlation analysis and redundancy analysis, a significant positive correlation was found between soil pH and ryegrass germination rate and plant height, particularly with the most pronounced impact on soil pH observed in the CB1.0 and SB0 (SB:HAP = 1:0) treatments. This study underscores the potential of CB/SB-SA-HAP composite materials in soil improvement and plant growth promotion, providing valuable insights for soil remediation, enhancement, and plant cultivation advancements in the agricultural sector.

Hydrogeological structures of karst features using hydrographs in an underground river basin formed in a peak cluster depression, southwest China

Understanding of the hydrological behaviors in different karst features is crucial for evaluating the hydrological storage and transfer functions of a karst system. In this study, the Maocun karst underground river system, characterized by typical karst features, was selected as the research area in the southwest region of China. The main objectives of this research are to analyze the hydrogeological structure characteristics of each karst feature and assess water storage capacity in different aquifer media. Frequency distribution curve (FDC) of electrical conductivity (EC) values revealed that recharge sources in the five karst features differed and varied according to the amount of precipitation. All hydrographs of water levels in five karst features were divided into three periods due to the presence of triple aquifer media in the basin. The spatial structure of each feature was interpreted by analyzing the variation characteristics of recession exponential coefficients (λ). Additionally, the ratios of fissure water, fracture water, and conduit water sources were calculated based on the recession curves of water levels. Results showed that fast water flow had the highest proportion in the relatively open subsystem located upstream, while fracture water flow had the lowest proportion. The slow water flow was the main pattern of water storage in the basin. Values of EC in water decreased with a well-connected spatial structure and high hydraulic conductivity. There were significant differences in the values of EC among conduit water, fracture water, and matrix water. These values were calculated using mathematical relationships between EC and water level hydrographs. The results indicated that the EC values in matrix water exceeded 200 μS/cm, while EC values in conduit water/channel water were below 100 μS/cm. Finally, hydrogeological conceptual models were constructed for five karst features based on the depletion characteristics of the aquifer media during each recession period. These characteristics were interpreted using variation curves of EC and hydrographs of water levels. These findings not only elucidated the characteristics of hydrogeological structures in multiple karst features, but also had significant implications for the assessment of karst water sources.

Effect of Anisotropy of Reduced Graphene Oxide on Thermal and Electrical Properties in Silicon Carbide Matrix Composites.

Reduced graphene oxide, due to its structure, exhibits anisotropic properties, which are particularly evident in electrical and thermal conductivity. This study focuses on examining the influence of reduced graphene oxide in silicon carbide on these properties in directions perpendicular and parallel to the direction of the aligned rGO flakes in produced composites. Reduced graphene oxide is characterized by very high in-plane thermal and electrical conductivity. It was observed that the addition of rGO increases thermal conductivity from 64 W/mK (reference sample) up to 98 W/mK for a SiC-3 wt.% rGO composite in the direction parallel to the rGO flakes. In the perpendicular direction, the values were slightly lower, reaching up to 84 W/mK. The difference observed in electrical conductivity values is more significant and is 1-2 orders of magnitude higher for the flakes' alignment direction. The measured electrical conductivity increased from 1.2710-8 S/m for the reference SiC sinter up to 1.55 × 10-5 S/m and 1.2410-4 S/m for the composites with 3 wt.% rGO for the perpendicular and parallel directions, respectively. This represents an enhancement of four orders of magnitude, with a clearly visible influence of the anisotropy of the rGO. The composite's enhanced electrical and thermal conductivity make it particularly attractive for electronic devices and high-power applications.