Search Results (137)

To investigate the influence of the water–cement ratio and erosion patterns on the deterioration of concrete in a sulfate corrosion environment, concrete specimens with different water–cement ratios were immersed in Na₂SO₄ solutions of varying concentrations (0%, 5%, and 8%). The immersion times were set at 0 days, 30 days, 60 days, and 90 days. Macro-scale compressive strength tests and micro-scale performance tests were conducted to obtain the damage morphology, micro-scale elastic modulus, and hardness of eroded concrete. Additionally, K-means clustering analysis was used to analyze the micro-mineral phases of the specimens, and SEM and XRD were employed to reveal the degradation mechanisms of sulfate erosion on the microstructure of concrete. The results indicated that the erosion products of calcium aluminate and gypsum in concrete gradually increased with the increase in Na₂SO₄ solution concentration and immersion time. In the early stages of erosion, the compressive strength and corrosion resistance coefficient of concrete showed a temporary upward trend, which then decreased as the erosion depth increased. From a microstructural perspective, erosion had a significant impact on the internal structure of concrete, while the elastic modulus and hardness of hydrated calcium silicate and calcium hydroxide under erosion showed relatively minor changes, both exhibiting a gradual decrease. The volume fraction of microporous pores gradually increased, further exacerbating the depth and extent of erosion. Full article

This work investigates the time-dependent changes in temperature, flow, and solidification microstructure under various cooling conditions. The mechanism of the effects of different pouring temperatures on the morphology and evolution of the solidification microstructure is explored. During gradual cooling, the temperature distribution remained consistent and the solid–liquid interface extended to its furthest extent. In contrast, water cooling generated the most pronounced temperature gradient at the solidification front, which was conducive to the development of columnar grains. Specifically, the maximum solidification rates at the center of the casting under the water-cooled copper mold, copper mold, and ceramic mold conditions were 2.71 mm/s, 1.45 mm/s, and 0.95 mm/s, respectively, with water cooling achieving the fastest rate. In the early stages of solidification, the flow velocity at the casting center was relatively high, and during slow cooling, the molten material tended to flow toward the surface. When air cooling was applied, the molten material at the center migrated outward, while under water cooling, the fluid moved in an upward direction. At a heat transfer coefficient of 100 W/(m²·K), the alloy primarily formed equiaxed grains; however, at 5000 W/(m²·K), the proportion of columnar grains increased significantly, and the average grain area expanded from 3.664 × 10⁻⁶ m² to 4.441 × 10⁻⁶ m². Additionally, as the pouring temperature increased from 1100 °C to 1200 °C, the number of grains decreased, while the average radius grew from 1.665 × 10⁻³ m to 1.820 × 10⁻³ m, resulting in a reduced fraction of equiaxed grains. This study provides valuable theoretical insights for optimizing the solidification process of this particular alloy. Full article

Between 2022 and 2023, the urban soils of Forlì (NE Italy) were surveyed, sampled, analyzed, and mapped over an area of ca. 5700 ha, of which 2820 were sealed. The outcomes of the survey allowed the integration of the existing knowledge about soil and land use with the urban plan and provided the basis to produce a 1:10,000 map of urban soils along with their land capability and an updated 1:50,000 soil map of the municipality. Soil data (textural fractions, pH, organic carbon content) were interpolated over the entire case study area, providing the inputs for locally calibrated pedotransfer functions whose outputs were used to assess a set of seven indicators for the potential supply of soil ecosystem services (SESs): soil biodiversity, buffer capacity, carbon storage, agricultural production, biomass production, water regulation, and water storage. Maps of the seven ecosystem services on a hybrid resolution grid of 25 and 100 m were complemented with an overall urban soil quality map based on the combinations of four different SES indicators. Results show that for several services, hotspots occur not only in the peri-urban agricultural areas but also in unsealed soils within the urban fabric, and that different soils provide high-quality services in diverse constellations depending on the soil characteristics, age and extent of disturbance and degree of sealing. Full article

Woody plants serve as crucial ecological barriers surrounding oases in arid and semi-arid regions, playing a vital role in maintaining the stability and supporting sustainable development of oases. However, their sparse distribution makes significant challenges in accurately mapping their spatial extent using medium-resolution remote sensing imagery. In this study, we utilized high-resolution Gaofen (GF-2) and Landsat 5/7/8 satellite images to quantify the relationship between vegetation growth and groundwater table depths (GTD) in a typical inland river basin from 1988 to 2021. Our findings are as follows: (1) Based on the D-LinkNet model, the distribution of woody plants was accurately extracted with an overall accuracy (OA) of 96.06%. (2) Approximately 95.33% of the desert areas had fractional woody plant coverage (FWC) values of less than 10%. (3) The difference between fractional woody plant coverage and fractional vegetation cover proved to be a fine indicator for delineating the range of desert-oasis ecotone. (4) The optimal GTD for Haloxylon ammodendron and Tamarix ramosissima was determined to be 5.51 m and 3.36 m, respectively. Understanding the relationship between woody plant growth and GTD is essential for effective ecological conservation and water resource management in arid and semi-arid regions. Full article

Cruciferous vegetables of the plant order Brassicales are an attractive dietary component and a valuable source of fiber. However, the nutritional–physiological properties are different when comparing soluble and insoluble fibers. Another significant impact is the transformation of fibers by different influencing factors during food preparation. Cruciferous vegetables, especially, are dominantly processed to soften the matrix. As a result, during cooking, the polysaccharides are dissolved, swelled, or degraded to a certain extent, influencing the composition and the nutritional–physiological properties. The aim of the present study was to analyze the impact of different cooking procedures on changes in the dietary fiber content profile of three different plants: white cauliflower (Brassica oleracea L. var. botrytis), broccoli (B. oleracea L. var. italica), and Brussels sprouts (B. oleracea L. var. gemmifera). The sample material was subjected to direct (“in the water”) and steam cooking. The dietary fiber content and the content of its fractions were determined using an enzymatic analysis method. The results of the research show that the cooking process had a significant influence on the content of dietary fiber fractions in cruciferous vegetables. The concentration of insoluble dietary fiber decreased, whereas the content of soluble dietary fiber increased. When considering the average influence of each process, both steam cooking and direct cooking had a similar impact on changes in the concentrations of dietary fiber fractions. It can therefore be concluded that, when considering dietary fiber content, both processes can be equally well chosen as a thermal treatment for cruciferous vegetables. Full article

Mangrove sediments serve as paleoenvironmental records of organic matter and nutrient accumulation. Ecuador, the world’s largest producer of whiteleg shrimp Penaeus vannamei in brackish waters, lost 43% of its continental mangroves between 1969 and 1999. Currently, more than 70,000 hectares of shrimp farms operate in estuaries with mangroves and within mangrove reserves. Variations in mangrove coverage and the extent of shrimp farms are described for the period 1996–2020 for two mangrove reserves, REMACAM and RVSMERM, with an observed increase in the extent of shrimp farms in both reserves. Four sediment cores obtained from mangrove drains and drains transformed into shrimp farm infrastructures were analyzed to observe the impact of this activity on the cumulative changes in total organic carbon (TOC) content and total nitrogen (TN) content, the fractionation of stable isotopes δ13C and δ15N, as well as the TOC/TN ratio. The mangrove drains in REMACAM had 3.8 times more TOC and 2.3 times more TN than drains transformed into shrimp farms in RVSMERM, with lower TOC/TN ratios. The organic matter in sediments from sectors with a higher proportion of shrimp farms mainly came from particulate organic matter of freshwater and freshwater algae compared to mangrove drains. Increases in TOC and TN content were recorded in all analyzed sectors, which could be attributed to the cumulative impact of population growth, the development of other agricultural crops, and continental deforestation, despite the fact that proportionally, the highest increases occurred in the sector with a greater influence of shrimp farms. Full article

A surface water extent downscaling framework was developed in the past using a floodability index based on topography. We presented here a new downscaling approach including several improvements. (1) The use of a new Floodability Index (FI), including better integration of auxiliary permanent waters (i.e., presence of water during the whole time record). By using this updated FI, the new downscaling became a true data-fusion with permanent water databases originating mainly from visible observations. (2) Some discontinuities between low resolution cells have been reduced thanks to a new smoothing algorithm. (3) Finally, a coastal extrapolation scheme has been presented to deal with coarse resolution data contaminated by the ocean. This new and complex downscaling framework was tested here on the GIEMS (Global Inundation Extent from Multi-Satellite) database but the approach is generalizable and any surface water database could be used instead. It was shown that this new downscaling procedure (including several processing steps, algorithms and data sources) is a significant improvement compared to the previous version thanks to the new floodability index and the downscaling processing chain. Compared to the previous version, the downscaling results (GIEMS-D) were more coherent with the permanent water database and preserved better the original low-resolution information (e.g., mean scare error water fraction (0–1) of 0.0041 for the old version, and 0.0018 for the new version, over flooded areas in the Amazon). GIEMS-D has also been evaluated at the global scale and over the Amazon basin using independent datasets, showing an overall good performance of the downscaling. Full article

Optimizing irrigation profit is essential for enhancing agricultural productivity and ensuring sustainable water resource management, especially under the uncertainties caused by climate variability. It signifies that maximizing irrigation profits has become the primary consideration of current agricultural irrigation systems. By discussing the change in irrigation profits with irrigation fraction $f$, which represents the proportion of irrigated farmland per unit area of cultivated land, a new method of qualitative diagnosis of irrigation supply and demand balance was proposed by means of the optimal irrigation fraction $f_0$ corresponding to the objective function $y\left(f\right)$ and the correlation coefficient $\rho$ between irrigation water demand anomalies $\widehat{D}$ and irrigation water withdrawal anomalies $\widehat{I}$ ($\rho \left(\widehat{D},\widehat{I}\right)=0$). It will serve as a new attempt to optimize irrigation profits. We argue that the optimal objective function $y\left(f_0\right)$ represents the state of equilibrium of irrigation supply and demand. This study proposes a reverse optimization idea, which includes two comparison methods, to estimate the comprehensively optimal irrigation fraction $f_0$ that maximizes irrigation profits and irrigation profit per unit area while minimizing risks associated with climatic anomalies. By demonstrating that $f_0$ performs exceptionally well in meeting the objectives of maximizing irrigation profits and minimizing risks across various climatic scenarios, we suggest a robust method for optimizing irrigation profits, which simply calculates $\rho \left(\widehat{D},\widehat{I}\right)\left(f\right)=0$ because $\rho \left(\widehat{D},\widehat{I}\right)$ is the function of $f$. Since $f_0$ could capture the optimal solution to the greatest extent. It can serve as a simple and effective solution to determine the optimal objective function $y\left(f_0\right)$ and diagnose the state of balance between irrigation water demand and supply. This method offers practical implications for water resource management and agricultural planning in the face of climate change. Full article

PLA biocomposites, incorporating 5% wt. of lignocellulosic fibres (LF) from Posidonia oceanica waste with different degrees of cellulose purification, were obtained by melt blending and compression moulding. The LF were obtained after removing part of the non-cellulosic components by subcritical water extraction at 150 and 170 °C and after bleaching the extracted residues with hydrogen peroxide or sodium chlorite. The non-bleached LF provided the composites with a brown colour and opacity, while the bleached LF impacted the optical properties of composites to a lower extent, depending on their whiteness. The LF composition had a noticeable effect on the composites’ mechanical and barrier properties. All LF reduced the water vapour barrier capacity while promoting the oxygen barrier of the films. Bleached LF enhanced the film stiffness and reduced extensibility and resistance to break, whereas non-bleached LF had lower impacts on the tensile parameters. Considering the mechanical and barrier performance of the composites, the fibres obtained at 170 °C and bleached with sodium chlorite exhibited the best behaviour. Nevertheless, if transparency and colour are not limiting for the use of the films, untreated LF allowed for good preservation of the water vapour permeability of PLA films and enhanced the oxygen barrier capacity, with a similar mechanical response as the other non-bleached fractions. Full article

Floods, one of the costliest, and most frequent hazards, are expected to worsen in the U.S. due to climate change. The real-time forecasting of flood inundations is extremely important for proactive decision-making to reduce damage. However, traditional forecasting methods face challenges in terms of implementation and scalability due to computational burdens and data availability issues. Current forecasting services in the U.S. largely rely on hydrodynamic modeling, limited to river reaches near in situ gauges and requiring extensive data for model setup and calibration. Here, we have successfully adapted the Forecasting Inundation Extents using REOF (FIER) analysis framework to produce forecasted water fraction maps in two U.S. flood-prone regions, specifically the Red River of the North Basin and the Upper Mississippi Alluvial Plain, utilizing Visible Infrared Imaging Radiometer Suite (VIIRS) optical imagery and the National Water Model. Comparing against historical VIIRS imagery for the same dates, FIER 1- to 8-day medium-range pseudo-forecasts show that about 70–80% of pixels exhibit absolute errors of less than 30%. Although originally developed utilizing Synthetic Aperture Radar (SAR) images, this study demonstrated FIER’s versatility and effectiveness in flood forecasting by demonstrating its successful adaptation with optical VIIRS imagery which provides daily water fraction product, offering more historical observations to be used as inputs for FIER during peak flood times, particularly in regions where flooding commonly happens in a short period rather than following a broad seasonal pattern. Full article

Ion-adsorption rare earth element (REE) deposits are a major source of REEs and are found mainly in China. The formation of such deposits is affected by a combination of endogenic and exogenic factors. This study investigated the effect of micro-topography on the REE distribution in four weathering profiles at different topographic sites on a knoll in Hedi, Zhejiang Province, China. The weathering profile and REE accumulation are both most developed at mid-slope positions of the knoll. The intensity of chemical weathering decreases in the order of mid-slope > base > summit. As weathering progressed, REE enrichment initially increased but later decreased, with a progressive increase in light/heavy REE fractionation. REE fractionation is more pronounced on the north-facing slope than on the south-facing slope. Weathering degrees and clay mineral characteristics are key factors influencing the varying REE distributions on the knoll. Water leaching and the evolution of clay minerals towards higher maturity reduce REE adsorption capacity. Clay minerals also play a significant role in REE fractionation; the abundance of these minerals and the presence of illite enable the retention of more HREEs with minimal desorption. Taking into account water content, it is inferred that hydrological conditions, modulated by the micro-topography, strongly affect the depth and extent of REE accumulation, as well as fractionation. Full article

Microplastics (MPLs) and nanoplastics (NPLs) are smaller particles derived from larger plastic material, polymerization, or refuse. In context to environmental health, they are separated into the industrially-created “primary” category or the degradation derivative “secondary” category where the particles exhibit different physiochemical characteristics that attenuate their toxicities. However, some particle types are more well documented in terms of their fate in the environment and potential toxicological effects (secondary) versus their industrial fabrication and chemical characterization (primary). Fourier Transform Infrared Spectroscopy (FTIR/µ-FTIR), Raman/µ-Raman, Proton Nuclear Magnetic Resonance (H-NMR), Curie Point-Gas Chromatography-Mass Spectrometry (CP-gc-MS), Induced Coupled Plasma-Mass Spectrometry (ICP-MS), Nanoparticle Tracking Analysis (NTA), Field Flow Fractionation-Multiple Angle Light Scattering (FFF-MALS), Differential Scanning Calorimetry (DSC), Thermogravimetry (TGA), Differential Mobility Particle [Sizing] (DMPS), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Scanning Transmission X-ray Microspectroscopy (STXM) are reviewed as part of a suite of characterization methods for physiochemical ascertainment and distinguishment. In addition, Optical-Photothermal Infrared Microspectroscopy (O-PTIR), Z-Stack Confocal Microscopy, Mueller Matrix Polarimetry, and Digital Holography (DH) are touched upon as a suite of cutting-edge modes of characterization. Organizations, like the water treatment or waste management industry, and those in groups that bring awareness to this issue, which are in direct contact with the hydrosphere, can utilize these techniques in order to sense and remediate this plastic polymer pollution. The primary goal of this review paper is to highlight the extent of plastic pollution in the environment as well as introduce its effect on the biodiversity of the planet while underscoring current characterization techniques in this field of research. The secondary goal involves illustrating current and theoretical avenues in which future research needs to address and optimize MPL/NPL remediation, utilizing nanotechnology, before this sleeping giant of a problem awakens. Full article

Snow cover is a relevant component of the Earth’s climate system, influencing water supply, ecosystem health, and natural hazard management. This study aims to monitor daily snow cover in the Cantabrian Mountains using Sentinel-2, Landsat (5–8), and MODIS data processed in Google Earth Engine (GEE). The main purpose is to extract metrics on snow cover extent, duration, frequency, and trends. Key findings reveal significant spatial and temporal variability in Snow-Cover Days (SCDs) across the region. Over the past 23 years, there has been a notable overall decrease in snow-cover days (−0.26 days per year, and −0.92 days per year in areas with a significant trend). Altitudes between 1000–2000 m a.s.l. showed marked decreases. The analysis of Snow-Cover Fraction (SCF) indicates high interannual variability and records the highest values at the end of January and the beginning of February. The effectiveness of satellite data and GEE is highlighted in providing detailed, long-term snow cover analysis, despite some limitations in steep slopes, forests, and prolonged cloud-cover areas. These results underscore the capacity for continuous monitoring with satellite imagery, especially in areas with sparse snow observation networks, where studies could be enhanced with more localized studies or additional ground-based observations. Full article

Vine shoots hold promise as a biomass source for fermentable sugars with efficient fractionation and conversion processes. The study explores vine shoots as a biomass source for fermentable sugars through pretreatment with two deep eutectic solvents mixtures: choline chloride:lactic acid 1:5 (ChCl:LA) and choline chloride:ethylene glycol 1:2 (ChCl:EG). Pretreatment conditions, such as temperature/time, solid/liquid ratio, and biomass particle size, were studied. Chemical composition, recovery yields, delignification extent, and carbohydrate conversion were evaluated, including the influence of washing solvents. Temperature and particle size notably affected hemicellulose and lignin dissolution, especially with ChCl:LA. Pretreatment yielded enriched cellulose substrates, with high carbohydrate conversion rates up to 75.2% for cellulose and 99.9% for xylan with ChCl:LA, and 54.6% for cellulose and 60.2% for xylan with ChCl:EG. A 50% acetone/water mixture increased the delignification ratios to 31.5%. The results underscore the potential of this pretreatment for vine shoot fractionation, particularly at 30% solid load, while acknowledging the need for further process enhancement. Full article

Nitrile butadiene rubber (NBR) and its various composite materials are widely employed as friction materials in mechanical equipment. The use of carbon nanotube (CNT) reinforcement in NBR for improved friction and wear characteristics has become a major research focus. However, the mechanisms underlying the improvement in the friction and wear characteristics of NBR with different CNT contents remain insufficiently elucidated. Therefore, we conducted a combined analysis of NBR reinforced with varying CNT contents through molecular dynamics (MD) simulations and ring–block friction experiments. The aim is to analyze the extent to which CNTs enhance the water-lubricated friction and dry wear properties of NBR and explore the improvement mechanisms through molecular chain characteristics. The results of this study demonstrate that as the mass fraction of CNTs (0%, 1.25%, 2.5%, 5%) increases, the water-lubricated friction coefficient of NBR continuously decreases. Under water-lubricated conditions, CNTs improve the water storage capacity of the NBR surface and enhance lubrication efficiency. In the dry wear state, CNTs help reduce scratch depth and dry wear volume. Full article