Wet Conditions Research Articles

Precision water recharge facilitates spikelet development and seed growth in Carex schmidtii: Implications for near-natural restoration of degraded semi-arid wetlands.

The expansion of irrigated agriculture in semi-arid regions exacerbates the degradation of wetland ecosystems. Precision water recharge can facilitate near-natural restoration of degraded wetlands by alleviating the conflict between wetlands and agricultural water use. However, although the ecological significance of precision water recharge as a nature-based solution for restoring wetland vegetation has been widely acknowledged, the mechanisms driving its role in spikelet development and seed growth in Carex schmidtii Meinsh. remain poorly understood despite their critical impact on reproduction and genetic information transfer. To address this knowledge gap, this study compared the characteristics of spikelet development and seed growth in C. schmidtii under four hydrological conditions (drought, moist, water depth of 5cm, and water depth of 10cm) and four re-watering treatments (maintaining constant water levels and re-watering to the initial hydrological regime on the 15th, 30th, and 45th days). We also investigated the ecological and photosynthetic characteristics of the leaves. The hydrological conditions and re-watering treatments significantly affected spikelet development, seed growth, leaf development, and photosynthetic pigment accumulation in C. schmidtii. Compared to other treatments, moist conditions and re-watering to the initial hydrological regime on the 15th day (IH2-RT2) significantly enhanced spikelet characteristics (length, diameter, and biomass) and seed growth traits (length, width, height, volume, thousand-seed weight, and seed test weight). Furthermore, leaf ecological characteristics (length, width, perimeter, and area) and chlorophyll content (chlorophyll a, b, and total chlorophyll) in C. schmidtii under IH2-RT2 exhibited higher values compared to other treatments. Spikelet development characteristics and seed growth traits exhibited significant correlations with leaf ecological characteristics and chlorophyll content. The interaction between leaf ecological characteristics and chlorophyll content explained 39.64% and 43.15% of the variation in spikelet development and seed growth, respectively. A structural equation model further demonstrated that hydrological regimes and re-watering treatments directly affected spikelet development and seed growth while indirectly influencing spikelet development and subsequent seed growth by altering leaf width and chlorophyll b content. Overall, hydrological regimes and re-watering treatments significantly influenced spikelet development and seed growth in C. schmidtii through multiple pathways. The utilization of flood and snowmelt water resources, along with the integrated management of agricultural and wetland water resources, can serve as key strategies for the efficient use of water resources in semi-arid regions. This study provides important insights for wetland vegetation restoration in semi-arid regions worldwide.

Mechanical Characterization of Amniotic-Based Scaffolds Containing Silk Fibroin and Sodium Alginate Nanofibers.

Due to its availability and biocompatibility, the human amniotic membrane (hAM) is being investigated by a large number of researchers with the goal of gaining a better understanding of the materials' mechanical behavior and structural integrity and optimizing them for various Tissue Engineering applications. In this research, biopolymers sodium alginate (SA) and silk fibroin (SF) were electrospun onto a decellularized hAM, resulting in two types of hybrid scaffolds: hAM/SF and hAM/SF/SA. The mechanical characteristics of these nanofibers were then analyzed to guide scaffold optimization for applications using these materials. Two mechanical experiments were conducted; uniaxial tension in both wet and dry configurations, and stress-relaxation tests. According to the results, the mechanical characteristics of the manufactured materials were significantly different from those of the amniotic membrane, indicating the effect of novel materials. Tensile testing in the dry condition revealed a small variation in stiffness between the amniotic membrane and the new nanofibers. Simultaneously, a significant reduction in maximum tension and stretch was observed in the aforementioned materials compared to amniotic matrices. In addition, tensile testing in a wet configuration indicated that the new nanofibers are stronger and stiffer than amniotic membrane but less stretchy, owing to the improved mechanical properties of SF, which can be considered as the membrane's or tissue's load-bearer. The addition of SF increases the stiffness and durability of the fabricated scaffold. In addition, when compared to the amniotic membrane, relaxation tests revealed significant differences in peak tension rather than equilibrium state for the novel nanofibers in wet conditions. The results of this investigation will enable us to have a comprehensive grasp of the mechanical properties of freshly created wound dressings.

Designing nanohydrogels/organosilica composite membranes to stabilize CO2 separation performance in dry and wet conditions

Designing nanohydrogels/organosilica composite membranes to stabilize CO2 separation performance in dry and wet conditions

Ryegrass root-soil composites mechanical properties and its slope stability: Experimental study and numerical analysis

ABSTRACT Urbanization and infrastructure projects generate huge amount of construction and demolition waste (CDW), posing significant challenges for the environment and human health. In order to reduce the environment and safety risks caused by the CDW landfills, this study was amid to utilize plant roots to develop a root-CDW-soil system for strengthening the CDW and enhancing the slope stability of CDW landfills. A series of experimental analyses were conducted, focusing on shear tests of root-soil composites under various moisture conditions and root content ratios. The results indicate that the inclusion of ryegrass roots plays a critical role in significantly enhancing the shear strength of the soil, and the soil samples reinforced with 0.6 g of ryegrass roots exhibited a shear strength increase of up to 35% compared to the unreinforced samples. The slope stability treated by the plant roots was evaluated by finite element simulations under different rainfall conditions. The factor of safety (FoS) for reinforced slopes increased from 1.18 to 1.59 after five days of heavy rainfall (480 mm/d), highlighting the significant improvement in stability provided by the root systems. These findings suggest that the root-soil system offers a sustainable solution for slope management, reducing risks associated with construction waste and extreme weather conditions. Implications: Urbanization and infrastructure projects generate significant waste, posing environmental and safety challenges. This study investigates the enhancement of slope stability through the integration of ryegrass root systems. The findings indicate that ryegrass roots substantially improve soil shear strength and overall slope stability. Furthermore, the study demonstrates that these root systems enhance resilience to heavy rainfall, thereby mitigating the risk of slope failure. These results suggest that plant root systems offer a sustainable solution for slope management, effectively addressing environmental concerns related to construction waste and extreme weather conditions. This research provides a comprehensive understanding of the physical and mechanical properties of root-soil composites, thereby promoting their practical application in slope stabilization.

High pressure processing at different hydration levels as a tool to enhance rice bran stability and techno-functionality.

High-pressure processing (HPP) enhances food safety and shelf life by inactivating microorganisms and preserving food quality, yet its effectiveness in low-humidity environments has not been evaluated. This study investigated the effects of HPP at 500MPa for 15min across varying hydration levels (15, 30, 60, 77%) on rice bran (RB), aiming to identify microbial effectiveness, besides techno-functional and physicochemical properties. HPP effectively reduced mesophilic bacteria, molds and yeast of RB at>15% hydration level, achieving reductions of up to 4 logarithmic cycles in the latter, nearing the detection limit of the method. However, it did not significantly impact spore inactivation. HPP treatment of≥30% hydrated RB induced particles aggregation and a honeycomb formation. The interaction between hydration and HPP treatment significantly affected the distribution of total dietary fibers, with an increase in soluble dietary fiber from 8.73g/100g to 11.03g/100g after HPP treatment at 15% hydration level. Protein solubility was enhanced by hydration (15, 30 and 60%), and peroxide values decreased after HPP treatment at low hydration (≤30%) but increased when applied to high hydrated (>30%) RB. Emulsifying activity decreased upon HPP treatment of highly hydrated RB (≥60%), but more stable emulsions were achieved after HPP, regardless of the hydration level. Therefore, this study highlights the potential of HPP as a sustainable approach to enhance the utilization of rice bran in food applications, addressing existing knowledge gaps regarding its processing under different moisture conditions.

Development and evaluation of the modified and standardized rainfall anomaly indices for extreme variability analysis.

This study introduces two refined rainfall anomaly indices-the Modified Rainfall Anomaly Index (MRAI) and the Standardized Rainfall Anomaly Index (SRAI)-to address limitations in the traditional Rainfall Anomaly Index (RAI). The existing RAI struggles to effectively capture extreme wet and dry rainfall conditions and relies on a simplistic formulation. To evaluate these indices on a continental scale, data from the Integrated Multi-Satellite Retrievals for GPM (IMERG) was used for the Conterminous United States (CONUS), enabling scalability to ungaged locations and beyond. Additionally, daily annual maximum series (AMS) from 2,360 NOAA stations provided reference data to enhance the robustness of the analysis. IMERG data informed the MRAI and SRAI, while station data validated the RAI. Findings showed MRAI's kurtosis ranged from 0 to +0.9, consistently higher than SRAI and RAI, while SRAI exhibited a kurtosis range from -0.9 to -0.1. Median index ranges were -2 to 0 for SRAI, 0 to +2 for MRAI, and -1 to +1 for RAI. Comparing MRAI and RAI, performance metrics revealed average PRB of -23.5, RMSE of 0.93, MBR of 0.74, NSE of 0.82, and KGE of 0.53. For SRAI versus RAI, metrics showed PRB of -14.5, RMSE of 1.7, MBR of 0.8, NSE of 0.41, and KGE of 0.46. Spatially, MRAI effectively captured positive anomalies leaning toward wet extremes, while SRAI identified negative anomalies indicating dry extremes. These indices demonstrate significant potential for climate change studies, especially when applied together.

A novel skin temperature estimation system for predicting pressure injury occurrence based on continuous body sensor data: A pilot study.

Pressure injury prevention is important in older patients with immobility. This requires an accurate and efficient prediction of the development of pressure injuries. We aimed to develop a method for estimating skin temperature changes due to ischemia and inflammation using temperature sensors placed under bedsheets to provide an objective, non-invasive, and non-constrained risk assessment tool. This study consisted of a thermal skin simulation study and a descriptive correlation study in healthy participants. A thermal skin simulation study was conducted using a model reproducing the body surface (underwear, diaper, or wet diaper conditions) and bed environment. In a descriptive-correlational study, the participants lay supine on a mattress with a temperature sensor attached to their sacral skin. The thermal skin simulation study showed that temperature changes in the skin can be estimated under the sheets by inputting time-shifted temperature data into machine learning (R2=0.9967 for underwear, 0.9950 for diapers, and 0.9869 for wet diapers). It was also demonstrated that the absolute skin temperature of a healthy individual (N=17) could be estimated with the best accuracy by inputting time-shifted data into an extra-tree regressor (R2=0.8145). A combination of interface pressure and temperature sensors can be used to estimate skin temperature changes. These findings contribute to the development of a skin temperature measurement method that can capture temperature changes over time in clinical settings.

Assessing consistency in drought risks in India with multiple multivariate meteorological drought indices (MMDI) under climate change.

This study investigates the spatio-temporal consistency of different MMDI formulations and their role in meteorological drought characterization uncertainty under historic and future climates using ERA5 reanalysis, and outputs from eight Coupled Model Intercomparison Project Phase 6 models, respectively, across different climate zones and shared socioeconomic pathways (SSP) in the Indian subcontinent. Six MMDI formulations namely the Standardized Precipitation Evaporation Index (SPEI), Reconnaissance Drought Index (RDI), and self-calibrated Palmer Drought Severity Index (scPDSI), Standardized Palmer Drought Index (SPDI), Standardized Moisture Anomaly Index (SZI) and Supply Demand Drought Index (SDDI) are used. A suite of analysis including agreement mapping, category difference analysis and uncertainty contribution analysis using global sensitivity analysis (GSA) are employed to quantify the consistency of MMDIs and uncertainty in drought characterization due to the MMDI formulation. The variation in MMDI consistency due to different reference evapotranspiration (ETo) methods is also studied. Results demonstrate strong agreement among the MMDIs under historic climate. Under climate change scenarios our findings demonstrate broad agreement among majority of the MMDIs across the study domain, but in substantial areas where MMDI not agree, especially for higher emission scenarios and arid zones. Increased uncertainty under climate change is due to SDDI and SPEI projecting dryer conditions while scPDSI projecting wetter conditions in the far future period owing to varying degrees of sensitivity of MMDIs to its constituent variables (Precipitation and ETo). Results also show that the uncertainty due to MMDIs varied considerably based on ETo methods as well. Finally, based on GSA analysis, the most significant sources of uncertainty in drought projections under climate change are attributed to MMDI-GCM interactions and MMDIs for the Penman-Monteith method. Discrepancies in drought estimates caused by the MMDI selection highlight the need for careful evaluation of drought indices before adopting for climate change impact assessment.

Impact of climate and human-induced fire on the Dongyuan Lake, Southern Taiwan during the last 1850 cal years BP

Impact of climate and human-induced fire on the Dongyuan Lake, Southern Taiwan during the last 1850 cal years BP

Effect of moisture in fire hoods and gloves on residual heat accumulation during repeated rest-work cycles at a fire scene.

Firefighters are exposed to the risk of burns at fire scenes. In 2020, the National Fire Agency of the Republic of Korea surveyed 50,527 firefighters and identified 242 burn-related incidents. The body parts affected by these burns were the hands (28.51%), ears (10.74%), and neck (10.33%), with hands and facial areas accounting for ∼50% of all burns. This trend implies that gloves and hoods do not provide sufficient protection against burns. Firefighters alternate between activity and rest during firefighting operations to enhance mission efficiency. However, the accumulated heat in their hood and gloves from these repeated cycles has not been considered thus far. This study investigated thermal accumulation patterns based on the moisture content of hoods and gloves, reflecting repeated cycles of work and rest for firefighters. Consequently, heat accumulation occurred in a dry state in both the hood and gloves, and the degree of heat storage was higher in the hood. The glove stored heat even when wet because of its multilayer structural characteristics. These results suggest that repeated activities (work-rest) with gloves and hoods under dry/wet conditions can generate residual heat and heat accumulation, causing burns on the hand and face. This study clearly demonstrated the impact of the moisture conditions of gloves and hoods in repetitive situations where they are exposed to relatively low levels of heat radiation and are then subject to rest periods. The results of this study are expected to be valuable in designing new protective gear to prevent burn injuries and developing efficient firefighting tactics.

Changes in arthropod family richness, activity-density, biomass and body-size differed along a grazing intensity gradient: Modulation of plant traits and soil moisture conditions.

Arthropods play a critical role in the functioning of grassland ecosystems, and are largely affected by herbivore grazing. However, the mechanisms of grazing affecting arthropod community, especially through modulating plant traits and soil properties, are still unclear. We investigated the variation in arthropod community variables including family richness, activity-density, biomass, and body size in typical steppe grasslands subject to grazing at four intensity levels (nil, light, moderate and heavy) in central Inner Mongolia (China), and analyzed the relationships of these variations with grazing-induced changes in plant traits, plant community attributes and soil properties. We found that (i) at the community level, arthropod family richness was lower in moderately-grazed than in both lightly- and heavily-grazed grasslands, but no significant difference was detected between grazing and no-grazing grasslands. The high arthropod community activity-density was found in plant communities with high plant leaf nitrogen content and low water content. (ii) With increasing grazing intensity, the biomass of arthropod community decreased, while the proportion of small-sized arthropods increased, and the family composition, especially the families of Coleoptera changed. (iii) The response of arthropods to grazing intensity differed among arthropod orders. The family richness of Coleoptera, Diptera and Homoptera increased with the increase of plant leaf water content and C:N ratio or the decrease of leaf nitrogen content; Orthoptera activity-density declined with increasing grazing intensity, but showed no significant correlation with plant leaf traits, community attributes, or soil water content; Hymenoptera activity-density declined with the increase of plant height, biomass and cover, and the decrease of plant individual density and family richness; a greater Lepidoptera activity-density was found in the grassland with high vegetation cover and moist soil; and Diptera exhibited larger biomass and body size in grasslands with increased plant nitrogen content. (iv) Depending on grazing conditions, some arthropod families may alter their feeding preferences and select more stable environmental conditions for survival, potentially weakening the inherent relationship between arthropods and plants. Our study implies it is necessary to incorporate the dynamics of ground arthropods into the grassland management for conservation and sustainable use of grassland ecosystems.

Experimental Study on Bond Fatigue Between Carbon Fiber-Reinforced Polymer Bars and Seawater–Sea Sand Concrete Under Seawater Immersion and Dry–Wet Cycle Conditions

The durability of carbon fiber-reinforced polymer (CFRP) bars in marine environments is essential for their application in seawater–sea sand concrete (SWSSC), especially under cyclic loading conditions. While previous studies primarily focused on static bonding performance, the effects of seawater immersion and dry–wet cycles on bond fatigue behavior at CFRP–SWSSC interfaces remain underexplored. This study investigated the bond fatigue performance of CFRP bars and SWSSC under seawater immersion and dry–wet cycling conditions. Eighteen CFRP bar-SWSSC bond specimens were divided into three categories and prepared for static and fatigue pull-out tests. The effects of varying stress levels (fatigue upper load/static bond ultimate load) after seawater immersion and dry–wet cycling on fatigue failure modes, bond–slip behavior, and fatigue characteristics were evaluated. The results show that seawater immersion and dry–wet cycling significantly degrade the performance of bonds between CFRP bars and SWSSC, with an average bond strength reduction of 10.31%. These conditions reduce fatigue cycles and stiffness while increasing bond–slip (relative displacement at the bar–concrete interface) and residual–slip (displacement after unloading). Moreover, dry–wet cycling has a greater negative impact on fatigue bond performance than seawater immersion. Higher fatigue stress levels exacerbate damage and crack propagation at the CFRP–SWSSC interface, leading to significant increases in both bond–slip and residual-slip. Under similar conditions, higher stress levels enhance bond stiffness. However, excessively high stresses may lead to bond fatigue failures. Using experimental data and existing fatigue bond–slip constitutive models, a customized model for CFRP bars in SWSSC was developed. These findings highlight that marine environments and fatigue loading severely impair bond performance, thereby emphasizing the importance of careful design for marine applications. The proposed model offers a reliable framework for predicting bond–slip behavior under fatigue conditions, enhancing the understanding of CFRP–SWSSC interactions and supporting the design of durable marine infrastructure.

Seasonal Variation and Key Controls of Groundwater Ammonium Concentrations in Hypoxic/Anoxic Riparian Sediments

AbstractThe seasonal controls of hydrology, temperature, hypoxia, and biogeochemical conditions for groundwater ammonium–N (NH4+) concentrations are not well understood. Here we investigated these controls for riparian groundwaters located upstream of two milldams over a period of 4 years. Groundwater chemistry was sampled monthly while groundwater elevations, hydraulic gradients, and temperatures were recorded sub‐hourly. Distinct seasonal patterns for NH4+ were observed which differed among the wells. For wells that displayed a strong seasonal pattern, NH4+ concentrations increased through the summer and peaked in October–November. These elevated concentrations were attributed to ammonification, suppression of nitrification, and/or dissimilatory nitrate reduction to ammonium (DNRA). These processes were driven by high groundwater temperatures, low hydraulic gradients (or long residence times), hypoxic/anoxic groundwater conditions, and increased availability of dissolved organic carbon as an electron donor. In contrast, NH4+ concentrations decreased in the riparian groundwater from January to April during cool and wet conditions. A groundwater well with elevated total dissolved iron (TdFe) concentrations had elevated NH4+ concentrations but displayed a muted seasonal response. In addition to hydrologic controls, we attributed this response to additional NH4+ contribution from Fe‐driven autotrophic DNRA and/or ammonification linked to dissimilatory Fe reduction. Understanding the temporal patterns and factors controlling NH4+ in riparian groundwaters is important for making appropriate watershed management decisions and implementing appropriate best management practices.

Design and optimization of tamarind seed polysaccharide-based scaffold for tissue engineering applications using statistical modeling and machine learning, and it's in-vitro validation.

This study explores the development and optimization of a novel biomaterial scaffold for tissue engineering, composed of Tamarind seed polysaccharide (TSP), Hydroxypropyl methylcellulose (HPMC), Chitosan (CS), and Sodium alginate (ALG). Scaffold properties, including swelling, degradation, porosity, mechanical strength, conductivity, and surface wettability, were analyzed. Using Response Surface Methodology (RSM) and Artificial Neural Network (ANN) modeling, the optimal scaffold (THAC) composition was determined to be 30.12% TSP, 21.69% HPMC, 12.05% ALG, and 36.14% CS. The ANN model outperformed RSM in predictive accuracy (R2>0.9). Mechanical testing demonstrated a Young's modulus of 0.905±0.103MPa and a compression strength of 0.398±0.028MPa, indicative of its resilience for cartilage engineering. Conductivity analysis revealed enhanced ionic conductance in wet conditions, highlighting its electrolyte-responsive behavior. Surface wettability tests showed a hydrophilic nature, with a contact angle of 58.08±6.84°, enabling superior water absorption. SEM analysis confirmed a uniform porous structure, while cytocompatibility studies with HeLa, MG -63 and ES-E14TG2a cells showed significant cell proliferation and attachment. These results underscore THAC's potential for applications in regenerative medicine, with the combination of RSM and ANN enabling precise tuning of scaffold properties for optimal performance in tissue engineering.

Interplay Among Recent Trends in Climate Extremes, Vegetation Phenology, and Crop Production in the Southern Mediterranean Region

ABSTRACTThe southern Mediterranean region is among the most vulnerable areas to climate change globally. However, in this region, there is a need to further understand the complex interactions between climate, vegetation, and crops to fully assess the combined impacts of extreme climate events on the agricultural sector. Using daily Normalised Difference Vegetation Index (NDVI) data, we evaluated trends across 15 vegetation phenology indicators between 1982 and 2019 and analysed their links to land‐use land‐cover changes. We found significant increases in the maximum value of NDVI (MaxV), length of growing seasons (LengthGS), and duration from crop emergence to anthesis (BMaxT), particularly within croplands. These changes positively correlated with regional crop production, especially in coastal and interior plains where croplands and forests are expanding. Conversely, southern areas bordering the Sahara showed declining MaxV and an expansion of sparsely vegetated areas. We then conducted a comprehensive seasonal trend analysis of climatic stresses and discussed how they align with recent trends in key phenological indicators. Coastal and interior plains experienced wetter conditions throughout the year, ensuring sufficient water during the growing season. Meanwhile, areas bordering the Sahara had wetter autumns and winters but drier springs and summers. Additionally, the region experienced warmer conditions from spring to autumn, with fewer cold wave events. Analysing the frequency and duration of compound extreme events, we observed a trend toward more light to moderate dry/hot days in spring and autumn and light to extreme wet/hot days from summer to autumn. These conditions are significantly correlated with increased MaxV, improved crop productivity, and extended LengthGS and BMaxT. These findings may serve as early indicators of how future climate changes could impact crop production, highlighting regional risks and opportunities to guide informed decision‐making and development of adaptive strategies in the southern Mediterranean region.

Precession modulates the poleward expansion of atmospheric circulation to the Arctic Ocean

Under sustained global warming, Arctic climate is projected to become more responsive to changes in North Pacific meridional heat transport as a result of teleconnections between low and high latitudes, but the underlying mechanisms remain poorly understood. Here, we reconstruct subarctic humidity changes over the past 400 kyr to investigate the role of low-to-high latitude interactions in regulating Arctic hydroclimate. Our reconstruction is based on precipitation-driven sediment input variations in the Subarctic North Pacific (SANP), which reveal a strong precessional cycle in subarctic humidity under the relatively low eccentricity variations that dominated the past four glacial-interglacial cycles. Combined with climate model simulations, we highlight that precession drives meridional shifts in the northern rim of the North Pacific Subtropical Gyre (NPSG) and modulates the efficiency of heat and water vapor transfer to the SANP and Arctic regions. Our findings suggest that projections of a northward shift of the NPSG in response to future global warming will lead to wetter conditions in the Arctic Ocean and enhanced sea-ice loss.

Determining Moisture Condition of External Thermal Insulation Composite System (ETICS) of an Existing Building

ETICS is a popular external wall insulation system, which is not without possible defects and damages. A frequent cause, direct or indirect, of damage to buildings is the impact of water (moisture). This article presents, among others, the results of tests of the moisture content of ETICS layers, the water absorption and capillary absorption of the render by means of the Karsten tube method, numerical thermo-moisture simulations, and tests of interlayer adhesion, in sample residential buildings. Mass moisture content testing of the wall substrate showed acceptable moisture levels (1–4%m) within masonry walls made of silicate blocks, as well as locally elevated moisture levels (4–8%m) in the case of reinforced concrete walls. Moisture testing of the insulation samples showed a predominantly dry condition, and testing of the reinforcement layer showed an acceptable level of moisture. Severe moisture was found in the sample taken in the ground-floor zone at the interface between mineral wool and EPS-P insulation underneath the reinforced layer. Capillary water absorption tests helped classify silicone render as an impermeable and surface hydrophobic coating. Tests of the water absorption of the facade plaster showed that the value declared by the manufacturer (<0.5 kg/m2) was mostly met (not in the ground-floor zone). The simulation calculations gave information that there was no continuous increase in condensation during the assumed analysis time (the influence of interstitial condensation on the observed anomalies was excluded). The tests carried out indicated the occurrence of numerous errors in the implementation of insulation works affecting the moisture content and durability of external partitions.

Spatial and temporal variability of soil moisture active and passive (SMAP) droughts and their impacts on vegetation in the Central Highlands of Vietnam.

Drought is a reoccurring natural phenomenon that presents significant challenges to agricultural production, ecosystem stability, and water resource management. The Central Highlands of Vietnam, a major region of industrial crops and vegetation ecosystems, has become increasingly vulnerable to drought impacts. Despite this vulnerability, limited research has explored the specific characteristics of drought and its seasonal effects on vegetation ecosystems in the region. This study addressed these gaps by providing a detailed analysis of recent soil moisture drought characteristics and their seasonal impacts on vegetation from 2015 to 2023 using weekly soil moisture active passive (SMAP) and moderate resolution imaging spectroradiometer (MODIS) satellite time series observations. This analysis derived the soil moisture anomaly index as a proxy to assess drought characteristics and used correlation analysis to quantify their impacts on seasonal vegetation dynamics. Our spatial analysis identified the most significant drought years in 2015 and 2019 in the study region, while the wettest conditions were detected in 2017 and 2022 over the study period. Notably, significant soil moisture deficits were observed in August and October throughout the study period, even though these months typically fall within the rainy season. On average, nearly 25 drought events were detected in the region from 2015 to 2023 due to soil moisture deficits, each lasting approximately 6 weeks. The impact of drought events on the vegetation ecosystem was seasonally pronounced in spring and winter, where droughts were notably higher. Our results provide valuable insights into informed decision-making and sustainable agricultural practices in the region. Understanding the spatial and temporal patterns of drought and its seasonal effects on vegetation can help policymakers and farmers develop targeted strategies to mitigate the adverse impacts, enhance water management practices, and promote drought-resistant crop varieties, thereby maintaining agricultural productivity and ecosystem health amidst increasing climate variability.

Alteration's Control on Frictional Behavior and the Depth of the Ductile Shear Zone in Geothermal Reservoirs in Volcanic Arcs

AbstractThe majority of geothermal energy is produced in tectonically active volcanic‐arc regions due to their high geothermal gradients. Reservoirs in these settings are often stratified with smectite/kaolinite‐, illite‐, and chlorite‐rich zones, in order of increasing depth and temperature. Eighteen andesitic core and surface samples were taken from five geothermal fields in the Lesser‐Antilles and Cascade volcanic arcs. The collected samples have experienced various degrees of alteration and can be considered, in their ensemble, to be representative of the previously mentioned alteration zones. The influence of the alteration was assessed through biaxial rate‐and‐state friction experiments on prepared gouge. The samples were each tested at 10, 30, and 50 MPa normal stress in both nominally dry and nominally wet conditions. While significant water‐induced frictional‐strength reduction was observed, phyllosilicate content dominates frictional behavior, with increased phyllosilicate content reducing frictional strength, promoting velocity‐strengthening behavior, and reducing frictional healing. Negative frictional healing is observed and likely related to the presence of expandable clays, leading to frictional weakness over long time periods. It is suggested that, by controlling frictional strength, phyllosilicate content influences the depth of onset of ductile shear zones, which often underlie these reservoirs and are critical for the horizontal advection and vertical sealing of geothermal fluid. Further, as these types of reservoirs are likely critically stressed, varying degrees of alteration within different reservoir zones can give rise to the formation of stress jumps. Overall, the frictional behavior depended to a first order on overall phyllosilicate content, potentially simplifying engineering studies.

Slip Risk on Surfaces Made with 3D Printing Technology

Slip risk on surfaces used by humans or active in mechanisms is studied to mitigate its effects or harness its beneficial outcomes. This article presents pioneering research on the risk of surfaces created using 3D printing technology. The study examines three materials (Polylactic Acid, PLA; Polyethylene Terephthalate Glycol, PET-G; and Thermoplastic Polyurethane, TPU), considering three print head movement directions relative to the British Portable Skid Resistance Tester (BSRT) measurement direction. In addition, surface roughness tests were performed. Dry tests showed that the structure created by the printing direction perpendicular to the movement direction is the safest in terms of slip risk. The SRVs of the measured samples on a qualitative scale were classified on this scale as materials with low or extremely low slip risk (ranging from 55 to 90 SRV dry and 35 to 60 SRV wet). Referring to the influence of the type of material on the SRV, it was found that the safest material in terms of reducing the risk of slipping in dry conditions is TPU and, in wet conditions, PLA. During wet tests, the best properties that reduce the risk of slippage in most cases are shown by the printing direction on a horizontal plane at an angle of 45° to the direction of movement. Statistical analysis showed that the printing direction and roughness do not have a statistically significant effect on the SRV, but the type of material and the type of method (dry and wet) and their interaction have a significant effect.