Search Results (109)

This study examined the effects of 2, 4 and 8% digestate-derived compost (DCP) on the retention/release of the fungicide penconazole (PEN), the herbicide S-metolachlor (S-MET) and the endocrine disruptor bisphenol A (BPA) in two agricultural soils sampled in Valenzano (SOV) and Trani (SOT), in Sothern Italy. DCP alone showed a conspicuous adsorption of the three xenobiotics, followed by their slow and scarce release. Sorption isotherm data of the compounds on unamended and DCP-amended soils were well described by the Freundlich model. Compared to unamended soil, the addition of the highest dose (8%) DCP to SOV increased the distribution coefficient, Kd, values of PEN, S-MET and BPA by 281%, 192% and 176%, respectively, while for SOT, the increases were 972%, 786% and 563%, respectively. Desorption of PEN and S-MET from all treatments was slow and partial (hysteresis), and only slightly reduced or unaffected by the addition of DCP, whereas BPA was almost entirely undesorbed in all treatments. Highly significant correlations between the adsorption coefficients of the three compounds in all soil treatments and the corresponding organic C contents confirm the prominent role of native and anthropogenic OM in the adsorption of contaminants and, consequently, in the control of their transfer into natural waters and/or entry in crop plants. Full article

With its unique environment and strategic value, the near space (NS) has become the focus of global scientific and technological, military, and commercial fields. Aiming at the problem of communication interruption when the aircraft re-enters the atmosphere, to ensure the needs of communication, navigation, and telemetry, tracking, and command (TT&C), this paper proposes an overall integration of communication, navigation, and TT&C (ICNT) signals scheme based on the K/Ka frequency band. Firstly, the K/Ka frequency band is selected according to the ITU frequency division, high-speed communication requirements, advantages of space-based over-the-horizon relay, overcoming the blackout problem, and the development trend of high frequencies. Secondly, the influence of the physical characteristics of the NS on ICNT is analyzed through simulation. The results show that when the K/Ka signal is transmitted in the NS, the path loss changes significantly with the elevation angle. The bottom layer loss at an elevation angle of 90° is between 143.5 and 150.5 dB, and the top layer loss is between 157.5 and 164.4 dB; the maximum attenuation of the bottom layer and the top layer at an elevation angle of 0° is close to 180 dB and 187 dB, respectively. In terms of rainfall attenuation, when a 30 GHz signal passes through a 100 km rain area under moderate rain conditions, the horizontal and vertical polarization losses reach 225 dB and 185 dB, respectively, and the rainfall attenuation increases with the increase in frequency. For gas absorption, the loss of water vapor is higher than that of oxygen molecules; when a 30 GHz signal is transmitted for 100 km, the loss of water vapor is 17 dB, while that of oxygen is 2 dB. The loss of clouds and fog is relatively small, less than 1 dB. Increasing the frequency and the antenna elevation angle can reduce the atmospheric scintillation. In addition, factors such as the plasma sheath and multipath also affect the signal propagation. In terms of modulation technology, the constant envelope signal shows an advantage in spectral efficiency; the new integrated signal obtained by integrating communication, navigation, and TT&C signals into a single K/Ka frequency point has excellent characteristics in the simulation of power spectral density (PSD) and autocorrelation function (ACF), verifying the feasibility of the scheme. The proposed ICNT scheme is expected to provide an innovative solution example for the communication, navigation, and TT&C requirements of NS vehicles during the re-entry phase. Full article

There is a lack of research on the early plastic deformation and capillary pressure of high-volume fly ash concrete (HVFAC) under varying ambient temperatures. This study aims to investigate the effects of water–binder ratio, fly ash admixture, and ambient temperature on the air entry time T, capillary pressure, and plastic shrinkage of HVFAC. Nine different fly ash concrete materials were designed and analyzed to determine the early plastic deformation and capillary pressure of HVFAC under different ambient temperatures. The dosage of different superplasticizers was adjusted to ensure a slump of 180 mm for all the HVFAC mixtures. The results showed that at 20 °C, T increases with the increase in the water–binder ratio and fly ash admixture, while the effect of T is negligible at 35 °C. The plastic shrinkage of HVFAC increases significantly with the increase in curing temperature, and there is a linear correlation between the air entry time T and the plastic shrinkage value at this time. At low water–binder ratios, the capillary pressure threshold P_a increases with increasing curing temperature, while at high water–binder ratios, there is no significant trend observed for P_a. The findings of the study can provide a theoretical basis for preventing plastic cracking of concrete and optimizing early curing methods. Full article

Guayule (Parthenium argentatum A. Gray) is a valuable domestic source for rubber and resin. At its center of origin in the Northern Mexico and Southern Texas deserts, guayule, a perennial shrub, is hybridized with its relative species mariola (Parthenium incanum Kunth). As rubber and resin are the main products derived from guayule, there is interest in using guayule bagasse as a bioenergy feedstock to meet the growing bioenergy and biofuel demands. This study aimed to explore and characterize phenotypic diversity in cell wall constituents (lignin, cellulose, and hemicellulose) and their yields among 51 guayule and mariola genotypes under two irrigation regimes (well-watered and water-stressed). Significant genotypic and environmental effects were observed for lignin, cellulose and hemicellulose concentrations, and yields, indicating the wide genetic variability of the collection for bioenergy-related traits. Moderate to high entry-mean heritability values for lignin, cellulose, and hemicellulose suggest that selection is feasible to enhance genetic gain. Significant positive correlations were found among cellulose and hemicellulose concentrations and yields, indicating the possibility to select multiple traits together during breeding cycles. High positive correlations between rubber and resin and lignin, cellulose, and hemicellulose yields highlight the opportunity to develop guayule germplasm with enhanced multi-use traits for industrial applications. Wide variations in drought stress indices (stress tolerance index, yield index, and yield stability index) underscore the environmental impact on the lignocellulosic traits. Several genotypes were identified with high stress index scores and could be parental candidates for improving guayule for arid and semi-arid sustainable agricultural systems. The current study is the first to characterize the phenotypic diversities in guayule and mariola for lignocellulosic components and yield, providing the foundation for future breeding efforts aimed at enhancing guayule’s value for diverse production goals and environmental conditions. Full article

The accurate measurement of soil suction is essential for understanding the behavior of unsaturated soils, particularly in soil–vegetation–atmosphere (SVA) interactions, where both energy and hydraulic gradients due to climatic action exhibit their maximum intensity. This study assesses the performance of the TEROS 21 probe, a capacitance-based water potential sensor, for measuring soil matric suction and temperature in clayey soils of the South Apennines, Italy. Laboratory tests were conducted on soil samples with varying moisture contents, and the results were compared with those obtained using the traditional filter paper (FP) method and high-capacity tensiometers (HCTs). The TEROS 21 (METER Group, Inc., Pullman, WA, USA) sensor demonstrated a reliable performance, especially at suction levels between 300 and 2000 kPa, though there was some dependency on the initial sensor conditions (wet or dry). The temperature data obtained from the TEROS 21 were verified by using a thermocouple, showing the high consistency of the readings. This study showed that the filter paper and sensor measurements aligned at a water content lower than 30% but diverged at higher levels due to method-specific accuracy limitations. The consistent sensor results confirmed the measurement’s reliability. The air-entry value (AEV) of the soil water retention data was identified at around 800 kPa, which is consistent with previous findings. Full article

Water environment evaluation is the basis of water resource planning and sustainable utilization. As a successful case of the coordinated progress of ecological protection and economic development, the Xin’an River Basin is a model for exploring the green development model. However, there are still some problems in the synergistic cooperation between the two provinces. Exploring the differences within the basin is a key entry point for solving the dilemma of synergistic governance in the Xin’an River Basin, optimizing the allocation of resources, and improving the overall effectiveness of governance. Based on the DPSIR model, 21 water environment–related indicators were selected, and the entropy weight–TOPSIS method and gray correlation model were used to evaluate the temporal and spatial status of water resources in each county of the Xin’an River Basin. The results show that (1) The relative proximity of the water environment in Xin’an River Basin fluctuated in “M” shape during the ten years of the study period, and the relative proximity reached the optimal solution of 0.576 in 2020. (2) From the five subsystems, the state layer and the corresponding layer are the most important factors influencing the overall water environment of the Xin’an River Basin. In the future, it is intended to improve the departmental collaboration mechanism. (3) The mean values of relative proximity in Qimen County, Jiande City, and Chun’an County during the study period were 0.448, 0.445, and 0.439, respectively, and the three areas reached a moderate level. The water environment in Huizhou District and Jixi County, on the other hand, is relatively poor, and the mean values of proximity are 0.337 and 0.371, respectively, at the alert level. The poor effect of synergistic development requires a multi–factor exploration of reasonable ecological compensation standards. We give relevant suggestions for this situation. Full article

The pore solution in expansive soil contains numerous chemical components that can significantly affect the soil’s water-retention properties, strength, and deformation. This study focuses on Ningming expansive soil and investigates the effects of varying concentrations of NaCl solutions on its water-retention characteristics. The soil–water characteristic curve of expansive soil over the full suction range was obtained using the pressure plate method. The microstructure of expansive soil was analyzed using mercury intrusion porosimetry and scanning electron microscopy. The results indicate that the water-retention capacity of expansive soil increases with higher concentrations of NaCl at equivalent suction levels. MIP tests demonstrated that, regardless of changes in pore solution concentration, the interparticle pores in pre-consolidated samples consistently dominate the pore structure, while agglomeration pores play a secondary role. Importantly, variations in the pore solution concentration primarily alter the characteristics of interparticle pores without significantly affecting their overall structure. SEM analysis revealed that the microstructure of pre-consolidated samples exposed to different pore solution concentrations exhibited less development than that of compactable samples, with a notable reduction in macropores. Furthermore, the arrangement of soil particles became increasingly uniform, and the stratification within the soil matrix was more pronounced. In addition, the Brooks–Corey (BC) model and van Genuchten (VG) model were employed to fit the measured data. It was found that the air entry values predicted by the two models were closely aligned with the measured data; therefore, it is recommended to utilize the average value as the air entry value corresponding to the changes in pore solution concentration of pre-consolidated Ningming expansive soil. Full article

The scanning curve of the soil–water characteristic curve (SWCC) represents the intermediate paths followed by soil as it transitions between the initial drying and main wetting cycles. The alternating occurrence of climatic conditions, such as rainfall and evaporation in different regions globally, provides a valuable framework for understanding how these dynamics influence the scanning curve. Monitoring the scanning curve can provide valuable insights for managing water resources and mitigating the impacts of drought, contributing to environmental sustainability by enabling more precise agricultural practices, promoting water conservation, and supporting the resilience of ecosystems in the face of climate change. It enhances sustainability by enabling data-driven designs that minimize resource use, reduce environmental impact, and increase the resilience of slopes to natural hazards like landslides and flooding. Available studies to determine the scanning curve of SWCC are limited and mostly conducted in the laboratory. This study aims to determine the real-time measurement of the scanning curve of SWCC for unsaturated soil. The research focuses on assessing the hysteresis behavior of residual soil slope from old alluvium through a combination of field instrumentation and laboratory testing. The pore size distribution was derived from the initial drying and main wetting SWCC. Field monitoring (scanning curve) indicates measurable deviations from the experimental results, including a 10% lower saturated water content and a 25% lower air-entry value. This study demonstrates the potential for field-based determination of scanning curves. It highlights their role in improving the prediction of the hydraulic behavior of residual slopes during varying climatic conditions. Full article

Background: Proteolytic cleavage of inactive pathogen proteins by furin is critical for their entry into human cells, and thus furin cleavage of the SARS-CoV-2 spike protein was identified as a prerequisite for virus binding and the subsequent infection of human cells in the recent COVID-19 pandemic. We report a water-aware structure-based protease inhibitor design study. Methods: Our efforts focused on the biological evaluation of small molecule inhibitors that emerged from a conserved water-aware virtual screening campaign of a library of compounds that shared structural or physicochemical properties with known furin inhibitors exhibiting newly recognized binding modes. Results: We identified a novel small-molecule furin protease inhibitor with a 1,3-thiazol-2-ylaminosulfonyl scaffold. Namely, the compound N-[4-(1,3-thiazol-2-ylaminosulfonyl)phenyl]-3-{(E)-5-[(2-methoxyphenyl)methylene]-4-oxo-2-thioxo-1,3-thiazolidin-3-yl}propionamide showed an IC₅₀ value of 17.58 μM, comparable to other published inhibitors. Conclusions: This compound could represent a starting point for the further design and development of non-peptidic, small-molecule furin inhibitors that could assist in furin cleavage studies and coronaviral pathogenesis. Full article

Understanding the spatial variability in soil hydraulic properties (SHPs) and their influencing variables is critical for ecohydrological and biogeochemical studies in coastal wetlands, where complex landscapes make it challenging to accurately delineate the spatial patterns of SHPs. In this study, soil samples were collected from two transects covered by Suaeda salsa (S. salsa) and Phragmites australis (P. australis) from the Beidagang Wetland Nature Reserve in northern China, and a comprehensive dataset on soil physical properties and SHPs was obtained by laboratory experiments. The results showed that soil physical properties (e.g., soil particle size, bulk density (BD), and soil organic matter (SOM)) displayed significant spatial variability, which was related to the physiological characteristics of S. salsa and P. australis and to soil depth. As a result, SHPs, including saturated hydraulic conductivity (K_s) and parameters of the van Genuchten model (θ_s-saturated soil water content, including α, the reciprocal of the air-entry value, and n, the pore size distribution index) varied considerably along the two transects. Specifically, K_s, θ_s, and α were negatively correlated with BD and pH, while positively correlated with SOM, which promoted soil aggregation to enlarge soil pores. Soil depth was shown to significantly affect SHPs, whereas the differences in SHPs between the two transects were not statistically significant, suggesting vegetation type did not directly impact SHPs. Soil water retention capacities were noticeably higher in surface soils, especially when soil suctions were less than 1000 cm, whereas their differences between depths largely diminished with further increasing soil suctions. This study highlights the complex interplay of SHPs with surrounding environments, providing critical insight for characterizing the spatial patterns of SHPs in coastal wetlands. Full article

This study introduces a conceptual model for understanding the hydromechanical behavior and zonation within tailings storage facilities (TSFs) constructed using the hydraulic backfill method, which constitutes over 98% of TSFs worldwide. The model identifies four distinct zones—dike, discharge, transition, and distal—each characterized by unique physical, geotechnical, and hydraulic properties. Key findings highlight gradients in parameters which systematically vary from the dam toward the settling pond. This study observes that seven parameters such as grain size, friction angle, shear strength, dry density, permeability, shear wave velocities, and liquefaction capacity decrease in value from the dike to the lagoon. Conversely, thirteen parameters such as fine content, porosity, cohesion, plasticity, degree of saturation, volumetric and gravimetric water content, capillary height, specific and volumetric surface of tailings, suction, air and water entry value in the soil water characteristic curve increase in value from the dike to the lagoon. These trends underscore the complex behavior of tailings and their implications for stability, drainage, and environmental impact. By integrating geological, geotechnical, hydrogeological, and geophysical data, this study provides a holistic framework for TSF management, addressing both current challenges and long-term environmental considerations. Full article

With the acceleration of urbanization, clay with significant variations in organic matter content is commonly encountered in infrastructure construction. Its unique water retention capacity is crucial for engineering safety and stability. This study uses red clay as the matrix and incorporates peat to prepare soil samples with varying organic matter content. Soil–water characteristic tests were conducted using the pressure plate method, filter paper method, and vapor equilibrium method to obtain the soil–water characteristic curves across the entire suction range. Subsequently, scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) tests were performed to analyze the mechanisms underlying the water retention characteristics. The experimental results indicate that the three different suction tests accurately reflect the soil–water characteristic curves of organic clay across the entire suction range. As the organic matter content in the soil increases, the air entry value and residual value of the soil samples exhibit a linear relationship with the organic matter content, enhancing the soil’s water retention capacity. The increase in organic matter content alters the microstructure of the clay, transforming the mineral–organic aggregates from ellipsoidal to plate-like shapes. While organic matter can influence the water retention of clay, within a certain suction range, the water retention capacity of organic clay is also related to the pore structure and the state of water within the pores. This is crucial for ensuring engineering safety and optimizing design solutions. Full article

Rainfall-induced landslides are widely distributed in many countries. Rainfall impacts the hydraulic dynamics of groundwater and, therefore, slope stability. We derive an analytical solution of slope stability considering effective rainfall based on the Richards equation. We define effective rainfall as the total volume of rainfall stored within a given range of the unsaturated zone during rainfall events. The slope stability at the depth of interest is provided as a function of effective rainfall. The validity of analytical solutions of system states related to effective rainfall, for infinite slopes of a granite residual soil, is verified by comparing them with the corresponding numerical solutions. Additionally, three approaches to global sensitivity analysis are used to compute the sensitivity of the slope stability to a variety of factors of interest. These factors are the reciprocal of the air-entry value of the soil α, the thickness of the unsaturated zone L, the cohesion of soil c, the internal friction angle ϕ related to the effective normal stress, the slope angle β, the unit weights of soil particles γ_s, and the saturated hydraulic conductivity K_s. The results show the following: (1) The analytical solutions are accurate in terms of the relative differences between the analytical and the numerical solutions, which are within 5.00% when considering the latter as references. (2) The temporal evolutions of the shear strength of soil can be sequentially characterized as four periods: (i) strength improvement due to the increasing weight of soil caused by rainfall infiltration, (ii) strength reduction controlled by the increasing pore water pressure, (iii) strength reduction due to the effect of hydrostatic pressure in the transient saturation zone, and (iv) stable strength when all the soil is saturated. (3) The large α corresponds to high effective rainfall. (4) The factors ranked in descending order of sensitivity are as follows: α > L > c > β > γ_s > K_s > ϕ. Full article

Landslides are a common occurrence that results in both human and financial losses each year around the world. The conventional methods use a variety of techniques, such as the application of lime, cement, and fly ash, for slope stabilization. Nevertheless, all these materials, to some extent, have their own shortcomings. In this study, multi-walled carbon nanotubes (MWCNTs) application was investigated for slope stabilization. Extensive saturated and unsaturated laboratory testing as well as numerical analyses were conducted in this study for both scenarios of soil with and without MWCNTs. The result from unsaturated testing demonstrates that the air-entry value and saturated volumetric water content of soil with MWCNTs increased compared to soil without MWCNTs, while the unsaturated permeability of soil stabilized with MWCNTs decreased. The result from the SEEP/W analysis during rainfall shows that the pore-water pressure (PWP) in the slope without carbon nanotubes was higher than the PWP in the slope with MWCNTs in the surface area. During rainfall, the factor of safety (FoS) of the slope without MWCNTs declined rapidly and at a high rate according to the Slope/W analysis, whereas the FoS of the slope with MWNCTs only changed slightly and remained safe when compared to the non-stabilized slope. Full article

Weathering processes of rocks lead to the formation of residual soil layers, which are typically characterized by a deep groundwater table and a thick unsaturated zone. Hence, the calculation of a slope’s safety factor under the influences of climatic circumstances is a function of unsaturated characteristics, such as the soil–water characteristic curve (SWCC). To determine the SWCC, the volume of the soil specimen must be determined in order to compute the void ratio and degree of saturation. The drying processes of the soil specimen led to uneven soil volume change during laboratory SWCC testing, demanding the development of a soil shrinkage curve. Several methods for measuring soil volume change have been developed over the years. However, there are significant limitations, and it is rarely used due to the difficulty linked to accurately measuring the soil volume during drying processes. In this study, a revised scanning approach is developed to evaluate residual soil volume change utilizing 3D scanning technology. The proposed method is applied in a case study on residual soil from the Old Alluvium in Singapore. The laboratory data and analysis results suggested that 3D scanning technology should be required to provide a correct estimation of the air-entry value of soil. Full article