Search Results (393)

Bioenergy production from agro-industrial waste has the potential to contribute to climate change mitigation. In Brazil, the pequi (Caryocar brasiliense Camb.) production chain makes an economic, environmental, and social contribution. However, the collection and processing of the fruit produce large amounts of waste, such as the peel, whose improper disposal leads to significant environmental impacts. This study evaluated how moisture and carbonization temperature influence the energy properties of charcoal briquettes made from pequi peel waste. Carbonization was performed at two final temperatures (360 °C/480 °C) with a heating rate of 1.5 °C min⁻¹ and residence times of 4 h and 5 h 20 min, respectively. Carbonization yields were calculated based on dry mass. Briquettes were produced from pequi peel at moisture contents of 5%, 7.5%, and 10% (wet basis). After carbonization, the charcoal briquette samples were characterized by proximate analysis, higher heating value (HHV), bulk density, energy density, and mechanical durability. Carbonization temperature exerted a more pronounced effect on the properties of the carbonized briquettes than the initial moisture content. Carbonization at 480 °C increased the fixed carbon content (76.38%, 74.25%, and 75.10% for treatments 1, 2, and 3) and the HHV (25.10–25.31 MJ kg⁻¹), while reducing the gravimetric yield (32.84–33.25%). The influence of moisture content was more evident in carbonizations carried out at 360 °C, indicating a temperature-dependent interaction. The use of pequi peel for solid biofuel production promotes the valorization of agro-industrial residues and supports strategies aimed at the circular bioeconomy and the decarbonization of the energy matrix. Full article

Thermal conductivity is a key input parameter in geotechnical and shallow geothermal engineering, directly influencing the design, efficiency, and long-term performance of ground heat exchangers, energy piles, and ground-source heat pump systems. Reliable parameterisation of this property in sandy soils remains challenging due to nonlinear interactions between water content, bulk density, and soil structure. This study develops a machine-learning-based workflow for robust parameterisation of thermal conductivity in quartz-rich sands using a large, internally consistent laboratory dataset comprising 1716 samples, including 1455 moist measurements used for modelling, obtained from nationwide site investigations. Air-dry specimens were identified as laboratory-induced drying states and excluded to restrict the analysis to hydro-mechanical conditions representative of typical shallow subsurface environments. Several regression algorithms representing different modelling strategies were evaluated within a unified and reproducible framework and benchmarked against selected classical empirical formulations. Model performance was assessed using standard accuracy metrics together with diagnostics describing the functional stability of predicted thermal-conductivity surfaces. The results reveal a systematic trade-off between predictive accuracy and functional consistency, indicating that models optimised for accuracy may produce functionally unstable and less suitable parameterisations for engineering applications. Accuracy-optimised models frequently produce locally irregular parameter fields, whereas more strongly regularised models yield smoother and physically more coherent response surfaces. The proposed workflow supports reliable thermal-property parameterisation for geotechnical design and shallow geothermal modelling. Full article

Repeated wetting–drying cycles accelerate scouring and deteriorate soil structure by increasing pore-water pressure. This study examines the durability of sand treated with zein biopolymers subjected to wetting–drying cycles and compares its uncycled condition with that of xanthan gum (XG). The treated specimens are prepared with biopolymer contents of 1% and 3% by mass of sand. The specimens are cured for an initial period of 7 days under atmospheric conditions, whereafter they are subjected to a series of wetting–drying cycles. Subsequently, the dimensions and mass of the specimens are measured to evaluate bulk density-related changes during the cycles. The strength and degradation characteristics of the specimens are evaluated through unconfined compression tests after being subjected to different numbers of cycles. The bulk unit weight after the drying phase remains nearly constant, whereas that after the wetting phase increases with both the number of cycles and biopolymer content. Overall, specimens with higher biopolymer content exhibit lower bulk unit weights. The XG-treated specimens show earlier strength improvement than the zein-treated specimens due to the faster curing-related strength development associated with water-based gelation. Moreover, the XG-treated sand rapidly fails after the first wetting phase, while the compressive strength of the cycled zein-treated specimens is lower than that of the uncycled specimens. Zein-treated sand with 3% biopolymer content shows a higher durability index after 10 cycles than sand treated with 1% biopolymer content. Therefore, a higher zein content can be used to enhance the durability of sand subject to frequent wetting and drying cycles. Full article

Tamarillo (Solanum betaceum) processing is characterized by early biomass exclusion and thermal stabilization, which may limit in-process retention of phytochemicals. This study evaluated an integrated sequence combining Flash Vacuum Expansion (FVE) under different processing conditions with whey protein-based cryostructuring as a strategy to enhance the redistribution and structural immobilization of tamarillo bioactives. FVE promoted migration of phenolics and pigments prior to mechanical fractionation. Selected FVE-treated puree was incorporated into a whey protein matrix and subjected to cryostructuring and freeze-drying to generate a porous stabilization scaffold. Structural characterization by scanning electron microscopy and gas adsorption confirmed the formation of an interconnected porous matrix. Cryostructuring reduced water activity to 0.17 ± 0.01 and produced high porosity (91.9%) with low bulk density (0.109 g·cm⁻³). Total phenolic retention exceeded 83%, while anthocyanins showed greater sensitivity (46% retention). No statistically significant additional losses of phenolics or antioxidant activity were observed during cryostructuring relative to gelation. The integrated approach illustrates a process-level stabilization pathway in which redistributed phytochemicals are physically confined within a porous scaffold, providing a structurally differentiated alternative to conventional drying for improved in-stream resource utilization. Full article

Fiber-reinforced aerogel composites are attractive for thermal protection applications because porous polymer networks can suppress heat transfer while maintaining structural stability. In this study, carbon fiber felt was integrated with a polyimide aerogel via a freeze-drying-assisted multicycle impregnation process to achieve controlled formation of interconnected aerogel networks within the fibrous scaffold. With increasing impregnation cycles, the composites exhibited progressive microstructural densification and improved structural stability. Although bulk density increased, thermal protection performance under prolonged butane-torch exposure was significantly enhanced, showing delayed backside temperature rise and improved resistance to structural degradation compared with bare carbon felt. Post-ablation analyses revealed the formation of a micro-/nanoporous polymer-derived char layer and a multilayer thermal-resistance structure, which contributed to suppressed heat transfer during flame exposure. These results indicate that effective thermal protection in CF/PA composites is governed by dynamic microstructural evolution and char-layer formation rather than intrinsic room-temperature thermal conductivity alone. The proposed multicycle impregnation strategy provides a scalable approach for designing lightweight polymer-based thermal protection materials operating in high-temperature environments. Full article

This study investigated the characteristics and bioactive properties of olive oils obtained from regional Nizip Yaglik (NY) and Kilis Yaglik (KY) olive varieties, encapsulated using maltodextrin (MD) and whey protein isolate (WPI) as wall materials. Olive oils were first emulsified with different WPI–MD ratios (1:1, 1:4, 1:10) and subsequently freeze-dried to produce microcapsule powders. A comprehensive evaluation was conducted, including physicochemical properties (encapsulation efficiency, moisture content, water activity, bulk density, flowability, wettability, particle size, and color), FTIR spectral profiles, morphological features, total phenolic content, and antioxidant activity. The results demonstrated that combining WPI with MD yielded high encapsulation efficiency and favorable reconstitution characteristics, effectively protecting sensitive bioactive constituents from oxidative degradation during processing and storage. Increasing the proportion of MD in the wall matrix improved emulsion stability and microencapsulation yield, while also slightly enhancing powder brightness. FTIR analyses confirmed that the fundamental chemical structure of olive oil was preserved across all formulations. The freeze-dried microcapsules displayed superior stability relative to non-encapsulated oils, retaining higher levels of phenolic compounds and antioxidant capacity. Among the formulations, elevated MD ratios enhanced powder flowability, whereas WPI played a crucial role in emulsification performance and capsule surface integrity. Overall, these findings underscore the effectiveness of MD–WPI blends as promising wall materials for the freeze-drying encapsulation of regional olive oils, offering a viable strategy to preserve their distinctive qualities and bioactive potential for functional food applications. Full article

Quartz, as an important non-metallic mineral, is widely used in many industrial fields. The shape characteristics of quartz particles are key factors affecting the bulk density, construction performance, and high-temperature performance of dry ramming mixes. This study focuses on quartz with seven different particle sizes from four different origins. Using digital image processing technology, geometric parameters such as flatness, circularity, and angularity of the particles (with a count equal to or exceeding 300 for each particle size category) were quantitatively analyzed, and the fractal dimension of quartz particles was calculated based on fractal theory. The results show that quartz from Luoyang exhibits the highest flatness, and quartz particles from Fengyang present the highest circularity, while the flatness and angularity of quartz particles from Xiangyang and Chengde are similar. The fractal dimensions of 20–100 mesh quartz particles from Fengyang are in the range of 1.027 to 1.060, greater than those of the other quartz particles. At smaller particle sizes, the shape of quartz from various origins tends to be regular (the circularity of particles of 70–100 mesh is >0.8). Through the quantitative characterization of parameters, the relationship between particle shape and size was revealed, which provided an important basis for selecting the raw materials and performing quality control for silica-based dry ramming mixes. Full article

This study evaluates the impact of a comprehensive design integrating precursor type, reduction and freeze-casting on the development of aerogels with high sorption capacity for engine oil. In this respect, the graphene oxide was varied from commercial to expanded; the reduction approach relied either on purely hydrothermal or combined hydrothermal–chemical reduction approaches. Following the synthesis, freeze-casting was applied at −5 °C and −196 °C. To further improve the reduction degree, annealing in an inert atmosphere was employed upon drying. The effects of precursors, reduction approach, freeze-casting and annealing were systematically investigated. Characterization techniques, including FT-IR, Raman spectroscopy, SEM, and EDS, were used to correlate the degree of reduction and morphological features of the porous structure with the absorption properties. The use of expanded GO as a precursor yielded aerogels with more homogeneous three-dimensional networks, a reduced bulk density of 3 mg cm⁻³, and lower oxygen-containing functional group content, thereby achieving consistently superior oil absorption of 270 g g⁻¹, with an oil occupancy of 94%. The process was found to fit well with the pseudo-first-order kinetic model. The results demonstrate that a comprehensive approach—considering combined reduction, freeze-casting, and thermal annealing—enables the tailored optimization of both the structure and absorption performance of GO aerogels for the remediation of oil spills. Full article

Soil compaction caused by uncontrolled machinery traffic is a major constraint to sustainable crop production. Controlled Traffic Farming (CTF), which restricts machinery movement to permanent lanes, has been practiced in New Zealand for more than a decade but has not been evaluated against Random Traffic Farming (RTF). This knowledge gap limits farmer awareness and adoption. This study hypothesized that CTF reduces soil compaction and improves soil physical properties compared with RTF. A one-year field experiment was conducted at Pukekohe, New Zealand, using annual ryegrass grown under CTF and RTF. Soil penetration resistance (PR), bulk density, total porosity, moisture content, and air-filled porosity were measured to a 40 cm depth. RTF increased soil PR relative to CTF across 10–40 cm. Bulk density was lower under CTF (0.96–1.03 g·cm⁻³) than RTF (1.11–1.30 g·cm⁻³), with improved total porosity (0.60–0.62 cm·cm⁻³) and aeration (12–23 cm·cm⁻³). CTF achieved a 5.7% higher bed-level yield. When scaled to the whole-field context, the productivity of tramlines contributed to 8% greater dry matter yield under CTF than RTF, indicating that the area allocated to tramlines did not negate the system-level productivity. This study provides the first New Zealand-specific empirical comparison of CTF and RTF to support adoption of CTF. Full article

Sustainable soil management is increasingly recognized as essential for crop health, productivity, and resilience, especially in vineyard ecosystems. Within the B-Wine project, biochar was evaluated as a soil amendment to improve physicochemical properties, water availability, plant eco-physiological functions, and yield. The trial was carried out in one growing season, one year after biochar application (16 t ha⁻¹ fresh weight ≈ 10.4 t ha⁻¹ dry weight) on three organically managed vineyards in the Chianti Classico region (Tuscany, Italy), integrating soil parameters (e.g., organic carbon content, soil moisture, saturated hydraulic conductivity, bulk density) and eco-physiological measurement (e.g., leaf water content, photosynthetic performance) with remote-sensing analysis of multispectral Sentinel-2 level-2A imagery from the Copernicus program and soil spectral measurements. Results indicated that biochar significantly improved key soil properties, although the magnitude of these improvements varied according to soil characteristics. Bulk density decreased by 5–16%, while soil organic carbon increase differed in the three sites, being nearly 50% in the medium-to-fine textured soils and exceeding 200% in the coarse-textured soil. The impact of biochar on saturated hydraulic conductivity varied depending on the soil, the type of biochar, and the moisture conditions. However, it improved the water balance of the vines and yield. Considering all three vineyard sites, the average yield increase was approximately 42%. However, this result was largely driven by pronounced responses at two sites, while the third showed no measurable increase, likely due to site-specific differences in soil properties and climatic conditions. Overall, biochar proved to be an effective, soil-dependent strategy for enhancing vineyard resilience, plant performance, and productivity under challenging conditions. Full article

Rapid urbanization threatens soil biodiversity and ecosystem functions, but the structural and physiological adaptations of soil microorganisms to urbanization remain unclear. We examined variations in soil microbial biomass, community structure and membrane lipid composition along an urban–suburban–exurban gradient in Guangzhou, China, using phospholipid fatty acid analysis. Samples were collected from four to five quadrats per site at three depths during dry and wet seasons. PERMANOVA revealed that both the urbanization gradient and the soil depth significantly shaped microbial communities. Depth was the strongest driver, explaining 45.5% of the variance in total microbial biomass, while site explained 27.2%. Microbial biomass decreased from exurban to urban sites and from surface to deep soils. Concurrently, the ratios of fungi/bacteria and Gram-positive/Gram-negative bacteria increased in urban areas and deeper soils. Physiologically, the membrane lipids shifted toward more saturated fatty acids in urban and surface soils, while unsaturated fatty acids predominated in exurban and deeper layers. These shifts in microbial community structure and membrane lipid composition were strongly correlated with key soil properties, including soil organic carbon, total nitrogen, and bulk density. The findings demonstrate urbanization diminishes microbial biomass and triggers adaptive microbial responses, providing a scientific basis for the sustainable management of urban forests. Full article

Organic amendments, including biochar and compost, are widely recognized for their potential to improve soil health, but their linkage to soil water functions (e.g., storage, infiltration, plant availability) is not clear. Over two years (2024–2025), we investigated soil water infiltration and associated soil health properties in response to soil amendment application under no-tillage conditions in semi-arid agroecosystems of the southwestern USA. Soil water infiltration was measured in biochar, compost, biochar and compost, and control plots using the SATURO dual-head infiltrometer. Soil physical and chemical properties, including bulk density (BD), soil moisture content (SMC), water-filled pore space (WFPS), residue cover, mean weight diameter (MWD) of dry aggregates, water-stable aggregates (WSA), pH, soil organic carbon (SOC), and total nitrogen (TN), were assessed at 0–15 cm soil depth. The results show a 31.5% higher infiltration rate along with, a small but statistically significant (3.7% lower) bulk density, and 119% greater wet aggregate stability in the biochar-amended plots than in the control plots. Compost with biochar also improved soil health, but infiltration responses were variable. Infiltration was positively correlated with residue cover and soil pH, whereas it was negatively correlated or not correlated with other soil properties. This study demonstrates that biochar under no-tillage conditions can enhance soil health and resilience of semi-arid agroecosystems by improving soil water functions. Full article

Nature-based Solutions (NbS) such as rolled cover crops are increasingly adopted in rainfed vineyards to reduce soil degradation and drought risk, but their effectiveness depends on local soil physical conditions. We compared spontaneous inter-row vegetation managed by mowing (Control) with a cereal-based rolled cover crop (C-R) in two vineyards of the Oltrepò Pavese (Northern Italy) with contrasting texture, structure, and slope: Canevino (CNV) and Santa Maria della Versa (SMV). From 2021 to 2025, continuous soil moisture monitoring was combined with field measurements of saturated hydraulic conductivity (K_s) and bulk density, interpreted using temporal indicators (MRD, ITS) and a drought index (SWDI) calibrated to field moisture thresholds. During wet phases, average saturation at 50 cm was consistently higher at SMV (about 78 to 84 percent) than at CNV (about 68 to 75 percent). Under water-limited conditions, management contrasts were most evident at SMV: at 50 cm during the post-termination dry phase, saturation remained around 70 percent under C-R versus about 64 percent under the Control, and K_s was higher under C-R (8.32 × 10⁻⁶ m/s in topsoil) than under the Control (7.39 × 10⁻⁶ m/s). At CNV, SWDI at 50 cm indicated a moderate improvement in one agronomic year (median −1.2 under C-R versus −5.3 under the Control in 2021 to 2022), while a full tillage operation in 2024 defined a disturbed phase that was interpreted separately. SWDI occasionally suggested severe drought levels not fully matching field evidence, highlighting the need for site-calibrated reference thresholds in structured fine-textured soils. Overall, soil physical properties set the hydrological envelope, while rolled cover management can enhance buffering and preserve conductive pathways during dry phases; therefore, NbS performance should be evaluated with site-adapted monitoring and cautious inference from temporally autocorrelated time series. Full article

Accurate numerical simulation of debris flows is essential for hazard assessment and early-warning design, yet high-fidelity solvers remain computationally expensive, especially when large ensembles must be explored under epistemic uncertainty in rheology, initial conditions, and topography. At the same time, field observations are typically sparse and heterogeneous, limiting purely data-driven approaches. In this work, we develop a deep-learning Fourier Neural Operator (FNO) as a fast, physics-consistent surrogate for one-dimensional shallow-water debris-flow simulations and demonstrate its application to the Rendinara–Morino system in central Italy. A validated finite-volume solver, equipped with HLLC and Rusanov fluxes, hydrostatic reconstruction, Voellmy-type basal friction, and robust wet–dry treatment, is used to generate a large ensemble of synthetic simulations over longitudinal profiles representative of the study area. The parameter space of bulk density, initial flow thickness, and Voellmy friction coefficients is systematically sampled, and the resulting space–time fields of flow depth and velocity form the training dataset. A two-dimensional FNO in the $(x,t)$ domain is trained to learn the full solution operator, mapping topography, rheological parameters, and initial conditions directly to $h(x,t)$ and $u(x,t)$, thereby acting as a site-specific digital twin of the numerical solver. On a held-out validation set, the surrogate achieves mean relative $L^2$ errors of about 6–$7\%$ for flow depth and 10–$15\%$ for velocity, and it generalizes to an unseen longitudinal profile with comparable accuracy. We further show that targeted reweighting of the training objective significantly improves the prediction of the velocity field without degrading depth accuracy, reducing the velocity error on the unseen profile by more than a factor of two. Finally, the FNO provides speed-ups of approximately $36\times$ with respect to the reference solver at inference time. These results demonstrate that combining physics-based synthetic data with operator-learning architectures enables the construction of accurate, computationally efficient, and site-adapted surrogates for debris-flow hazard analysis in data-scarce environments. Full article

The adoption of conservation systems in agriculture has been increasingly explored as a strategy to improve soil quality and potentially influence greenhouse gas (GHG) emissions. This study reports the first assessment of GHG emissions within a long-term (14 years) agroecological field experiment evaluating soil management systems for onion (Allium cepa L.) production in a Humic Dystrudept (Cambissolo Húmico Distrófico, Brazilian Soil Classification System) in Southern Brazil. Three management systems based on permanent soil cover and crop diversification were evaluated in an onion–maize rotation: conventional tillage (CT) without cover crops, no-till (NT) without cover crops, and a no-till vegetable system (NTV) with a summer cover crop mixture of pearl millet (Pennisetum americanum), velvet bean (Mucuna aterrima), and sunflower (Helianthus annuus). Short-term GHG emissions were monitored during one onion growing season (106 days), while soil chemical and physical properties reflect long-term management effects. Evaluations included (i) daily and cumulative GHG (N₂O, CH₄, and CO₂) emissions, (ii) soil carbon (C) and nitrogen (N) stocks, (iii) soil aggregation, porosity, and bulk density in different soil layers (0.00–0.05, 0.05–0.10, and 0.10–0.30 m), and (iv) onion yield and cover crop dry matter production. The NTV system improved soil physical and chemical quality and increased onion yield compared to NT and CT. However, higher cumulative N₂O emissions were observed in NTV, highlighting a short-term trade-off between increased N₂O emissions and long-term improvements in soil quality and crop productivity. All systems acted as methane sinks, with greater CH₄ uptake under NTV. Despite higher short-term emissions, the NTV system maintained a positive C balance due to long-term C accumulation in soil. Short-term greenhouse gas emissions were assessed during a single onion growing season, whereas soil carbon stocks reflect long-term management effects; CO₂ fluxes measured using static chambers represent ecosystem respiration rather than net ecosystem carbon balance. These results provide an initial baseline of GHG dynamics within a long-term agroecological system and support future multi-year assessments aimed at refining mitigation strategies in diversified vegetable production systems. Full article