Search Results (276)

Engineering sizing of seasonal underground thermal energy storage (SUTES) systems remains constrained by the complex coupling of heat and moisture transport in unsaturated porous media. Neglecting these coupling effects can lead to significant errors in the design of borehole length and spacing. This study presents a three-dimensional numerical investigation of a coaxial borehole heat exchanger (CBHE) field over a full annual cycle, including storage, transition, extraction, and recovery stages. A coupled heat–moisture transfer model for the soil–CBHE system is developed and validated against experimental data, yielding mean relative errors of 6.8% for temperature and 7.7% for volumetric water content. The model is then used to quantify the sensitivity of SUTES performance to the initial volumetric water content (θ₀). Increasing θ₀ from 0.20 to 0.40 m³·m⁻³ enhances the average heat injection rate per unit depth by 6.6% (from 53.84 to 57.39 W·m⁻¹) and the heat extraction rate by 7.1% (from 23.73 to 25.41 W·m⁻¹). This enhancement is primarily attributed to increased effective thermal conductivity and heat capacity, together with moisture migration and the associated latent-heat effects within the soil matrix. While the variations in seasonal energy and exergy efficiencies are within 1 percentage point, radial soil-temperature uniformity and effective heat diffusion are significantly improved in moister soils. These findings clarify the coupled transport mechanisms in borehole seasonal storage and provide engineering guidance for sizing CBHE fields in unsaturated formations. Full article

Maintaining ballast performance in seasonal frozen regions is essential for resilient and sustainable railway infrastructure because freeze–thaw-driven fouling can shorten service life and increase maintenance-related material consumption. To investigate the deterioration mechanisms of fouled railway ballast in seasonal frozen regions, freeze–thaw cycle tests and cyclic loading model tests were conducted in sequence using a custom low-temperature geotechnical system. The test results processed by Origin software indicate that unfrozen water migrates toward the freezing front under temperature gradients and forms ice lenses during freezing. During thawing, meltwater is retained above the underlying frozen soil. Repeated freeze–thaw cycles therefore promote progressive water accumulation in the upper soil layers, eventually forming a clay layer with high water content. Under cyclic loading, interlayer thickening exhibited clear moisture thresholds relative to the clay liquid limit (LL = 24%). Below the LL (18–24%), ballast penetration and fines migration were limited and thickness increased slowly. Above the LL, rapid strength loss accelerated penetration and upward transport. At an initial water content of 32%, fines migration surpassed the ballast surface and the ballast became fully fouled, meaning that the fouled interlayer thickness equaled the full 100 mm ballast-layer thickness. Fouling severity increased sharply with moisture: the void contaminant index exceeded the maintenance criterion (VCI > 40%) at 28% water content and evolved into severe mud pumping at higher concentrations. Excess pore water pressure developed stratification with depth, maintaining an upward hydraulic gradient near the interface and yielding a net water loss of 2.24–6.91% in the upper fine-grained layer. These quantified thresholds and mechanistic insights provide actionable trigger points for condition-based maintenance and climate-adaptive design, helping extend track-bed service life and reduce resource-intensive ballast renewal in seasonal frozen regions. Full article

Coal slime, typically with particle sizes below 1 mm, is difficult to utilize directly and is frequently associated with energy loss and environmental burden. This study comparatively investigates hot–air drying and transient steam flash drying for the dehydration and upgrading of filter–pressed coal slime. In hot–air drying, elevated temperature and reduced particle size markedly accelerate the drying rate, and the apparent activation energy ranges from 18.39 to 20.96 kJ·mol⁻¹ for different particle sizes. For steam flash drying, the influences of steam pressure, particle size, and holding time on moisture–removal efficiency and physicochemical structure are evaluated. The dehydration performance is enhanced by higher steam pressure and larger particle size, reducing the moisture content of the coal slime from 38% to 20%, with approximately 80% of the total water removed during the transient depressurization stage. Structural analyses reveal partial decomposition of oxygen–containing functional groups and mesopore contraction after flash treatment. Compared with hot–air drying, steam flash drying achieves shorter processing time and lower specific energy consumption. These findings indicate that steam flash drying is governed by a pressure–induced phase transition and enhanced thermodynamic driving force, providing an intensified pathway for the efficient upgrading of high–moisture coal slime. Full article

Background: Artemisia annua L. is a medicinal plant with documented antimicrobial, antioxidant, and anti-inflammatory properties. Although widely studied for internal therapeutic applications, its topical use—especially in hydrogel-based systems—has not been thoroughly investigated. The aim of this study was to develop sodium alginate hydrogels containing Artemisia annua extract, supplemented with hyaluronic acid and dexpanthenol, and to evaluate their physicochemical characteristics as well as their biological activities in vitro and in vivo. Methods: Select bioactive constituents of the Artemisia annua extract were quantified using liquid chromatography coupled with electrospray ionization mass spectrometry (LC-ESI-MS). Hydrogels were prepared by cross-linking sodium alginate with a calcium carbonate–glucono-delta-lactone system and were formulated with or without hyaluronic acid and dexpanthenol. Physicochemical evaluations included measurements of moisture content, water-retention capacity, gelation time, and pH. The hydrogel microstructure was examined by scanning electron microscopy (SEM). Antioxidant activity was assessed using three methods: the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, the ferric reducing antioxidant power (FRAP) assay, and the cupric reducing antioxidant capacity (CUPRAC) assay. Biocompatibility and regenerative effects were analyzed using cell viability assays and an in vitro scratch wound model on human keratinocyte cells. In vivo wound-healing efficacy was examined in rats with full-thickness skin excisions. Results: The extract contained high levels of methylated flavonoids and sesquiterpenes characteristic of Artemisia annua. Hydrogels supplemented with hyaluronic acid and dexpanthenol exhibited improved hydration stability and higher porosity. All formulations demonstrated measurable antioxidant activity, and those containing hyaluronic acid showed the strongest effects. The preparations were biocompatible and enhanced keratinocyte migration in vitro, with the combined hyaluronic acid–dexpanthenol formulation promoting the fastest wound closure. In vivo, Artemisia annua hydrogels accelerated wound healing by two to three days compared with untreated wounds. Conclusions: These results confirm the promise of Artemisia annua hydrogels for topical wound care and highlight the beneficial contributions of hyaluronic acid and dexpanthenol to their structural and therapeutic performance. Full article

Although the market recently shifted toward low- or non-alcoholic drinks, the beer sector is an important branch of industry in Europe. It stimulates local economies and communities, thereby justifying the need for its development. Both economic and environmental benefits could be achieved through proper management of the generated by-products, enabling them to stay in a loop. Such an approach aligns with currently postulated sustainability-oriented trends. Herein, a solution for the simultaneous management of the two main by-products of beer production is described. The spent yeast (SY) was used as a potential binder for brewers’ spent grain (BSG)-based products, representing a highly innovative solution given the state of the art. Using SY without treatment or with minimal addition of common organic acids (citric, succinic, and tartaric) enabled efficient bonding of the final product. It yielded properties similar to those of commercial counterparts, with a flexural modulus exceeding 1 GPa and a flexural strength exceeding 6 MPa. Because of the nature of the applied raw materials and their inherent moisture sensitivity (water contact angle < 50°), the final product was coated with vegetable oil. The applied coating, after thermooxidation-induced crosslinking, protected against moisture and humidity (water contact angle > 80°), potentially broadening its application range. The application potential was confirmed from a technical point of view through the efficient manufacturing of disposable plates. Nevertheless, their implementation in industrial practice must be preceded by meeting proper criteria for food-contact materials related to the stability and odor of the plates and coatings and migration of their components into food products. Full article

Water resources in arid oases are extremely scarce, and the quality of irrigation water and groundwater depth are key factors affecting soil secondary salinization and maintaining high and stable crop yields. This study focuses on the oasis irrigation area of the 38th Regiment in Qiemo County, located in the extremely arid region at the southeastern edge of the Tarim Basin. For the first time, irrigation experiments with different water qualities, ranging from 0.5 to 3.0 g/L, were conducted under varying groundwater depths for multiple crops. Through indoor soil column experiments and numerical simulations of water and salt in the unsaturated zone, the study reveals the water and salt migration patterns in the root zones of watermelon, corn, jujube, and peanuts. It was found that the process of soil water and salt transport exhibits significant differentiation characteristics in the vertical direction, with the surface layer responding most rapidly to changes in moisture and salinity, while the middle and deep layers show certain lag and buffering effects. The study also examined the spatiotemporal distribution trends of soil water and salt under different water quality and quantity irrigation conditions, drawing nonlinear threshold response curves for groundwater depth and determining the optimal groundwater depth under various irrigation conditions. The results indicate: (1) for the four crops under freshwater (0.5 g/L) irrigation and actual irrigation water conditions, soil salinity is safe at groundwater depths of 1–2 m; (2) under slightly saline water (2.0 g/L) irrigation, the safe groundwater depth (GWD) ranges for corn, peanuts, watermelon, and jujube root zones are 3.5–4.2 m, 1.2–3.5 m, ≥2.9 m, and ≥1.6 m, respectively, with crop sensitivity ranking as “corn > peanuts > watermelon > jujube”; and (3) under saline water (3.0 g/L) irrigation, the salinity tolerance thresholds for corn and peanuts root zones are exceeded regardless of shallow or deep groundwater depths, while the upper limits of salinity tolerance thresholds for watermelon and jujube correspond to groundwater depths of 2.9 m and 2.1 m, respectively, with increased groundwater depth making soil salinity increasingly safe. The study proposes a “sensitive-suitable-reinforced” three-zone paradigm and constructs a threshold table for optimal crop layout in arid areas based on the synergistic dual factors of “water quality–water quantity,” providing a theoretical basis for crop layout considering the spatial heterogeneity of groundwater occurrence. This has guiding value for arid oases in addressing the dual stress of water quality deterioration and salinization. Full article

The red sandstone rock mass and sculptures within the Xumishan Grottoes exhibit multiple forms of weathering damage, including flaking, hollows, efflorescence, and salt efflorescence. Among these, flaking and salt efflorescence are the most pronounced, posing a severe threat to the long-term preservation of the cave’s cultural relics. This study employs SEM-EDS, XRD, XRF and IC techniques to conduct scientific analysis and characterization of the weathering products on the surface of red sandstone. By integrating the lithology of the red sandstone itself with its depositional environment, the study investigates the causes of surface weathering in red sandstone. Research findings indicate that the lithology of the cave site consists primarily of muddy siltstone, with gypsum and mirabilite present within the weathered red sandstone, alongside minor quantities of Epsom salt and chloride salts. The migration and enrichment of these soluble salts within the rock mass constitute the key chemical factors triggering efflorescence and spalling in sandstone. Concurrently, influenced by the grottoes’ environmental conditions, periodic temperature fluctuations and moisture migration further promote freeze–thaw cycles and the crystallization–dissolution cycle of salts, accelerating the weathering process of the red sandstone within the Xumishan Grottoes. Full article

Premature deterioration of reinforced concrete is driven largely by moisture and chloride ingress, which accelerate steel corrosion and shorten service life. This study investigates a dual strategy to enhance durability while supporting circular-economy goals: (i) incorporating coal-fired biomass ash (CBA) as a fine-aggregate replacement (0%, 20%, and 50%) and (ii) applying bio-inspired surface treatments to reduce transport pathways. To capture variability in CBA performance across different environmental and material contexts, two concrete systems—produced in India and the UK—were evaluated, each subjected to a distinct coating approach: a bacterial self-healing treatment or a cinnamaldehyde (CNM) organic barrier. Mechanical, transport, and multi-scale characterization was performed, including compressive strength, capillary absorption, chloride migration (NT Build 492), SEM/EDS, XRF, and XRD. The 20% CBA mixes maintained or slightly improved strength, while higher CBA contents increased porosity but reduced chloride transport in the UK mix. The bacterial coating reduced long-term water absorption by over 80% through CaCO₃ mineralization, offering strong moisture resistance. The CNM coating decreased chloride migration by up to 68% via hydrophobic and ionic-blocking effects. Overall, moderate CBA with self-healing treatment enhances moisture control, whereas higher CBA with CNM provides effective chloride protection, extending the service life of CBA-based concrete. Full article

This study investigated the effects of calcium carbide slag (CCS) (0–12 wt%) incorporation on the workability, electrochemical properties, durability, and microstructure evolution of sulfoaluminate cement (SAC) mortar. Results showed that increasing CCS content reduced mortar fluidity and shortened setting time, indicating that CCS accelerates early hydration. A 9% CCS content was determined to be the optimal dosage; at 28 days, compared to the control group, this dosage group exhibited a 6.53% increase in compressive strength, a 22.47% decrease in drying shrinkage, and a 0.279% decrease in mass loss. These performance improvements stemmed from CCS’s ability to inhibit pore connectivity and limit moisture migration. Electrochemical analysis further revealed that the 9% CCS dosage group had the highest charge transfer resistance and resistivity (30.00% higher than the control group), reflecting a denser matrix and greater ion transport resistance. Consequently, chloride ion permeability was significantly reduced, with electrical flux and diffusion coefficient decreasing by 39.98% and 28.89%, respectively. Microstructural observations confirmed that CCS promotes the formation and densification of hydration products, effectively improving the internal pore structure. While 9% CCS can serve as an effective functional supplementary material, its long-term durability and sustainability still face practical application challenges. Future research should focus on establishing predictive models for chloride ion permeation lifetime and conducting quantitative sustainability assessments of CCS-SAC composites, particularly evaluating material cost, energy consumption, and carbon dioxide emissions. Full article

In grain storage and transportation, biological activity, including respiration and metabolism, generates heat, creating temperature gradients that can induce moisture migration and form high-humidity areas. This accelerates fungal and insect activity, leading to quality degradation. Long-term, distributed temperature monitoring inside grain piles is essential for ensuring safe storage and early risk warning. Radio Frequency Identification (RFID) technology has become widely adopted in storage temperature monitoring due to its low cost, maintenance-free operation, and high security. However, traditional RFID systems have limited communication ranges, and the large size of storage facilities necessitates the deployment of multiple readers, which increases costs. Additionally, the high density and fluctuating moisture content of bulk grain lead to significant RF signal absorption and scattering, weakening the accessibility of purely wireless systems to deeper parts of the grain pile. To address these issues, a passive distributed temperature monitoring system based on RFID technology is proposed. The system utilizes RFID readers to harvest RF energy for passive power supply, with an external antenna ensuring stable energy harvesting and data transmission. Single-bus multi-point temperature sensor modules are integrated into the system, enabling distributed temperature measurements across grain piles or warehouses. Experimental results show that the system achieves a temperature collection success rate of 98%, with an accuracy of ±1 °C and a polling cycle of less than 30 s, providing a low-cost, battery-free, and scalable solution for grain storage monitoring, significantly improving storage quality. Full article

Earth–rock dams provide cost-effective flood control and water storage through the utilization of locally available materials, making them essential infrastructure for regional safety, agricultural development, and sustainability. Electrical resistivity methods offer an efficient, non-destructive means to detect internal defects and potential hazards within dam bodies, thereby supporting dam safety assessment and service life extension. In this review, we focus on sand and clay, the most commonly used materials in earth–rock dams. We summarize the main methods and instruments for measuring soil resistivity and comparatively analyze the applicability and limitations of different approaches. Emphasis is placed on the key factors influencing soil resistivity, and recent progress in modeling the resistivity of soil materials is reviewed. The results show that soil resistivity parameters can effectively characterize physical and mechanical properties, structural features, and moisture migration behavior, providing an important basis for soil property evaluation. However, current studies are largely based on macroscopic experiments, with limited investigation of microscopic mechanisms and a lack of unified testing standards, leading to discrepancies between theoretical models and measured data. In this review, we aim to provide a theoretical reference for research and engineering applications of resistivity characteristics in earth–rock dam materials. Full article

Mechanical coffee drying is an energy-intensive stage of postharvest processing that directly affects product quality and production costs. This study evaluated the technical and economic feasibility of using expanded polystyrene (EPS) as a thermal insulation material to improve the performance of a mechanical coffee dryer and to demonstrate its potential for sustainable reuse. Experiments were conducted using a total of 210 kg of wet parchment coffee (Coffea arabica L. var. Cenicafé 1) per treatment, corresponding to three experimental replicates of 70 kg each, dried at 50 ± 2 °C, comparing an EPS-insulated dryer (0.02 m thickness) with a non-insulated control. A theoretical model based on steady-state heat transfer through series resistances estimated energy losses and system efficiency for different insulating materials. Theoretical results indicated that EPS, polyethylene foam, and cork reduced heat losses by 58.1%, 54.3%, and 50.9%, respectively. Experimentally, EPS reduced drying time by 7.82%, fuel consumption by 13.9%, and energy demand by 9.5%, while increasing overall efficiency by 6.7% and reducing wall heat losses by 37.7%. Improved temperature stability enhanced heat retention and moisture migration behavior. Economically, EPS reduced operating costs, yielding annual savings of USD 81.5, a 0.45-year payback period, and an annual return on investment (ROI) of 10.86, confirming its viability as a cost-effective and sustainable solution for improving energy efficiency in mechanical coffee drying. Full article

Freeze–thaw cycles (FTCs) are a prevalent weathering process that threatens the stability of canal slopes in seasonally frozen regions. This study combines direct shear tests under multiple F-T cycles with coupled thermo-hydro-mechanical numerical modeling to investigate the failure mechanisms of slopes with different moisture contents (18%, 22%, 26%). The test results quantify a marked strength degradation, where the cohesion decreases to approximately 50% of its initial value and the internal friction angle is weakened by about 10% after 10 freeze–thaw cycles. The simulation reveals that temperature gradient-driven moisture migration is the core process, leading to a dynamic stress–strain concentration zone that propagates from the upper slope to the toe. The safety factors of the three soil specimens with different moisture contents fell below the critical threshold of 1.3. They registered values of 1.02, 0.99, and 0.78 within 44, 44, and 46 days, which subsequently induced shallow failure. The failure mechanism elucidated in this study enhances the understanding of freeze–thaw-induced slope instability in seasonally frozen regions. Full article

This study investigates the effects of saline reclaimed water recharge on soil salt accumulation and water migration in Xinjiang, China, aiming to provide scientific guidance for the sustainable utilization of reclaimed water in arid regions. Indoor vertical infiltration simulation experiments were conducted using reclaimed water with varying salinity levels (0, 1, 2, 3, and 4 g L⁻¹) to evaluate their impacts on soil water–salt distribution and infiltration dynamics. Results showed that irrigation with saline reclaimed water increased soil pH and significantly enhanced both the infiltration rate and wetting front migration velocity, while causing only minor changes in the moisture content of the wetted zone. When the salinity was 2 g L⁻¹, the observed improvement effect was the most significant. Specifically, the cumulative infiltration increased by 22.73% after 180 min, and the time required for the wetting peak to reach the specified depth was shortened by 21.74%. At this salinity level, the soil’s effective water storage capacity reached 168.19 mm, with an average moisture content increase of just 6.20%. Soil salinity increased with the salinity of the irrigation water, and salts accumulated at the wetting front as water moved downward, resulting in a characteristic distribution pattern of desalination in the upper layer and salt accumulation in the lower layer. Notably, reclaimed water recharge reduced soil salinity in the 0–30 cm layer, with salinity in the 0–25 cm layer decreasing below the crop salt tolerance threshold. When the salinity of the reclaimed water was ≤2 g L⁻¹, the salt storage in the 0–30 cm layer was less than 7 kg ha⁻¹, achieving a desalination rate exceeding 60%. Reclaimed water with a salinity of 2 g L⁻¹ enhanced infiltration (wetting front depth increased by 27.78%) and desalination efficiency (>60%). These findings suggest it is well suited for urban greening and represents an optimal choice for the moderate reclamation of saline-alkali soils in arid environments. Overall, this study provide a reference for the water quality threshold and parameters of reclaimed water for urban greening, farmland irrigation, and saline land improvement. Full article

Microbial polysaccharides are promising components for wound-care products. This study reports the development of wound-healing antimicrobial hydrogels, based on pullulan from Aureobasidium pullulans, combined with mesenchymal cell-derived conditioned medium. Structural characterization of pullulan was confirmed by FTIR and NMR. Twenty-three formulations containing pullulan, chitosan, gelatin, citric acid, and antimicrobial agents were prepared. Physicochemical screening identified optimal hydrogels: No. 22 (1.2% pullulan, 1.2% chitosan, 0.2% citric acid, 2.4% gelatin, 0.1% conditioned medium, 0.4% glutaraldehyde) and No. 23 (2.4% pullulan, no chitosan, the remaining components identical to those in No. 22). Both exhibited pH values of 5.34 and 5.49, moisture content of 92%, swelling capacities of 175% and 213%, and dynamic viscosity between 58–120 mPa·s. Cytotoxicity testing with human mesenchymal stem cells showed no significant toxicity, with both hydrogels supporting cell adhesion and proliferation. Antimicrobial assays demonstrated inhibitory activity against Staphylococcus aureus and Escherichia coli for both formulations; only hydrogel No. 23 inhibited Pseudomonas aeruginosa. In vitro scratch assays revealed that hydrogel No. 23 significantly promoted fibroblast migration, achieving 30.25% scratch closure after 24 h. The developed formulations combine favorable physicochemical properties with antimicrobial efficacy and regenerative potential, supporting further evaluation as advanced wound-healing and anti-burn dressings. Full article