Search Results (2,460)

The selection and breeding of salt-tolerant rice and the use of saline–alkali land for rice cultivation are crucial for food security. However, most studies have focused only on the seedling salt tolerance stage, with little research on the salt tolerance mechanisms during the reproductive growth period. This study selected the salt-tolerant rice line SR17, the salt-tolerant variety SR86, and the salt-sensitive variety IR29 as research subjects. Two salt stress gradients of 0% and 0.5% (7.8 dS m⁻¹) were established. Salt stress was applied continuously from rice transplanting to the maturity stage, and the differences in response mechanisms during the young panicle stage under long-term salt stress were analyzed. The results showed that, under salt stress, SR17 exhibited the least lipid peroxidation and membrane damage, followed by SR86, while IR29 suffered the most severe damage. SR17 and SR86 could reduce oxidative damage and maintain membrane system integrity by activating the antioxidant enzyme system and accumulating soluble proteins. In contrast, the antioxidant system in IR29 was insufficiently activated; this indicates that the adaptability of this variety to salt-induced oxidative stress is relatively poor. The chlorophyll content and most photosynthetic parameters in SR17 showed no significant changes, and leaf gas exchange performance and chlorophyll status were the least affected, whereas IR29 suffered severe damage. Agronomic trait investigation revealed that, compared with the control, SR17 exhibited the smallest reductions in plant height, spikelets per panicle, 1000-grain weight, grain yield per plant, and main spikelet number under salt stress, and the decreases in key yield-related indicators—effective panicle number, grain yield per plant, and seed setting rate—were not significant. This study confirms that SR17 possesses superior salt tolerance and holds potential for further breeding and multi-environment trials, while also providing an important basis for elucidating the physiological mechanisms of salt tolerance during the reproductive stage of rice. Full article

The transition from conventional silica nanoparticle (SiNP) production based on purified alkoxysilanes and high-temperature flame hydrolysis of silicon tetrachloride to renewable and waste-derived silicon resources requires more than precursor substitution. It requires a mechanistic understanding of how feedstock mineralogy, silicon speciation, impurity chemistry, and processing history propagate through dissolution, nucleation, condensation, gelation, aging, drying, and pore evolution to determine material performance, environmental burden, and manufacturing feasibility. Although previous reviews have established the technical feasibility of producing silica from secondary resources, their predominant organization by feedstock, synthesis route, or application provides limited ability to explain why nominally similar processes generate materials with markedly different structural and functional properties. This review addresses these through a resource-pull, feedstock-to-function framework that links resource chemistry and process design to critical material attributes, application-specific specifications, sustainability, and scale-up requirements. Agricultural residues, industrial by-products, geothermal resources, waste glass, and fluorosilicate streams are critically compared according to silicon form and phase, reactivity, impurity profile, compositional variability, purification demand, and attainable product quality. Particular attention is given to waste-derived alkaline silicate systems, in which molecular, oligomeric, and colloidal silica coexist and therefore require characterization beyond bulk SiO₂ concentration. Established and emerging processing strategies, including controlled combustion and alkaline extraction, alkali fusion, ambient-pressure drying, microwave and mechanochemical activation, biogenic and biomimetic templating, and continuous processing, are evaluated according to their mechanistic effects, technological maturity, structural control, and demands for energy, reagents, water, solvents, effluent treatment, and capital. Across these routes, gelation and aging emerge as critical transfer stages through which feedstock composition is translated into network connectivity, pore architecture, shrinkage behavior, and ultimately functional performance. Evidence from secondary-source aerogels further shows that properly controlled waste-derived systems can attain BET surface areas of approximately 350–500 m² g⁻¹, within the textural range of many alkoxide-derived materials, indicating that feedstock variability, impurity management, and process control are more important constraints than an inherently lower performance ceiling. On this basis, this review proposes a minimum evidence framework comprising feedstock traceability, intermediate-speciation and colloidal characterization, silicon mass balance, gelation and aging metrics, application-specific qualification criteria, performance-normalized life cycle and techno-economic assessment, process analytical control, and staged pilot validation. Collectively, these principles provide a mechanistically grounded basis for moving sustainable silica synthesis beyond isolated proof-of-concept demonstrations toward reproducible, scalable, application-matched, and commercially credible manufacturing platforms. Full article

Construction on very soft peaty clay remains a major geotechnical challenge due to its high compressibility and low-bearing capacity. The deep mixing method (DMM) is widely adopted for in situ stabilization using cement; however, environmental concerns associated with cement production have driven the search for sustainable alternatives such as geopolymers using low-carbon materials. Existing studies predominantly rely on dried peat, processed precursors such as fly ash or calcined ground rice husk ash (RHA), and high concentrations of alkali activators such as sodium silicate (Na₂SiO₃) and sodium hydroxide (NaOH), which increase both environmental and economic burdens. This study develops a novel waste-based geopolymer incorporating untreated brick kiln-derived RHA, activated solely with low-concentration NaOH, while completely eliminating Na₂SiO₃. The avoidance of precursor pre-treatment and Na₂SiO₃ significantly reduces processing energy, cost, and associated environmental emissions. A systematic investigation was conducted to determine the optimum mixing time for maximizing strength under field-relevant conditions. Mechanical performance was evaluated using unconfined compressive strength tests considering variations in binder content, curing duration (7, 28 days), alkali concentration (6, 3 M), and alkali-to-binder ratio (0.3, 0.5, 0.7). Failure characteristics were examined, and an integrated framework combining cost analysis, life cycle assessment, and grey relation analysis was employed to optimize mix design. The optimized geopolymer achieved 2.2 times higher strength than cement-treated soil, with 25% cost reduction and more than 85% reduction in environmental impact. These findings demonstrate a scalable and sustainable solution for stabilizing highly organic soils, while promoting the valorization of supplementary cementitious materials without energy-intensive preprocessing. Full article

The durability of alkali-activated materials (AAMs) in acidic environments is a key factor governing their suitability as sustainable alternatives to ordinary Portland cement (OPC). This study investigates the acid resistance of fly ash–slag alkali-activated mortars prepared with either seawater-based or distilled water-based activator solutions, thereby addressing the feasibility of substituting potable water in activator preparation. Eleven binder blends were tested, ranging from 100% fly ash (F100G0) to 100% ground granulated blast furnace slag (GGBS, F0G100) in 10% replacement increments, each prepared with both distilled-water (D-series) and seawater-based (M-series) activator solutions. Mortar cubes were exposed to hydrochloric acid (HCl) and sulphuric acid (H₂SO₄) after curing for 28, 60, 90, and 180 days. Durability was assessed through mass change, compressive strength retention, and ultrasonic pulse velocity (UPV), complemented by X-ray diffraction (XRD) analysis to elucidate mineralogical transformations. Results showed that acid resistance was governed primarily by binder composition: calcium-rich slag (C–A–S–H) systems deteriorated mainly by decalcification under acid exposure, whereas low-calcium fly ash (N–A–S–H) systems degraded more slowly by dealumination. Seawater activation did not significantly compromise acid resistance relative to distilled-water systems, with the two-activator series performing comparably under both HCl and H₂SO₄. Paired comparisons of the reported blend values showed small, age-dependent differences between the two-activator series: seawater activation modestly delayed strength loss under HCl at intermediate ages, while under H₂SO₄ it carried a small late-age penalty attributable to reaction of activator-derived chloride compounds with the acid; at most ages, the two series were statistically indistinguishable. X-ray diffraction showed essentially identical phase assemblages in the two series: no crystalline products formed under HCl, where an amorphous silica-rich residue accumulates on fly-ash-rich blends, whereas gypsum was the sole crystalline product under H₂SO₄, enhanced in seawater-activated fly-ash-rich blends. The findings clarify the role of marine ions in influencing acid degradation and provide guidance for designing sustainable binder systems for chloride- and sulphate-rich service environments. Overall, seawater is shown to be a viable substitute for potable water in activator preparation, retaining acid resistance comparable to distilled-water systems and supporting the development of more sustainable alkali-activated binders. Full article

Understanding the formation of high-total-dissolved-solids (TDS) groundwater is essential for mine-water source identification, treatment, and resource utilization in arid and semi-arid coal mining areas. However, previous studies have commonly focused on individual aquifers and have not adequately explained the hydrochemical differentiation and evolutionary relationships within shallow-to-deep multi-aquifer systems. Taking the Xiaojihan Coal Mine in northern Shaanxi as a case study, 90 surface-water and groundwater samples were analyzed using self-organizing maps (SOM), hydrochemical diagrams, major-ion ratios, chlor-alkali indices, mineral saturation indices, X-ray diffraction data, and permeability-TDS relationships. SOM identified three hydrochemical units broadly corresponding to shallow surface water and groundwater from the Quaternary and Luohe formations, groundwater from the Anding Formation, and deep groundwater dominated by the Zhiluo and Yan’an formations. Their mean TDS concentrations increased from 348.69 to 1341.80 and 2510.00 mg/L, respectively. Groundwater evolved from low-TDS, HCO₃-Ca-dominated shallow water to high-TDS, SO₄-Ca/Na-rich deep water. Shallow groundwater was mainly controlled by carbonate and silicate weathering, whereas deep groundwater was increasingly affected by prolonged water-rock interaction, gypsum and anhydrite dissolution, pyrite oxidation, and reverse cation exchange. The increase in deep-groundwater TDS was primarily associated with the enrichment of SO₄²⁻, Na⁺ + K⁺, and Ca²⁺. Lower permeability with depth slowed groundwater circulation, prolonged residence time, and enhanced mineralization. XRD data confirmed the occurrence of exchange-active clay minerals, while saturation indices showed that carbonate minerals were generally near saturation to supersaturated, whereas gypsum, anhydrite, and halite remained undersaturated and retained dissolution potential. These findings clarify the shallow-to-deep evolution mechanism of high-TDS groundwater and provide a scientific basis for mine-water source identification and targeted management in arid and semi-arid coal mining areas. Full article

During soybean processing, insufficient disruption of the soybean cell wall structure limits protein solubilization, thereby reducing the nutritional value and bioavailability of soybean-based products. In this study, ultrasound combined with NaHCO₃ was used to induce targeted modification of soybean tissue structure and interfacial protein properties, with the aim of improving protein extraction, soymilk stability, and the digestive properties of spray-dried soybean flour. The results showed that single ultrasound treatment and single alkali treatment could increase the protein extraction rate in soymilk. But compared with the untreated control, the combined treatment increased the protein dissolution rate from 70.04% to 81.12% and decreased the protein residue rate in okara to 19.74%. The treatment also reduced the average particle size from 132.60 µm to 90.61 µm, increased the emulsifying activity index to 35.49 m²/g. Further experiments showed that the combined treatment of ultrasound and alkali increased the content of interface protein and modified protein conformation. These changes contributed to the improvement of storage stability and ionic stability of soymilk. Furthermore, the resulting spray-dried soybean flour exhibited a more uniform particle distribution with reduced interparticle agglomeration, higher solubility (88.37%), and higher in vitro digestibility (89.48%). Overall, the combined treatment enhanced protein solubility and interfacial behavior, thereby improving soymilk stability and soybean flour quality. These findings provide a useful theoretical basis for the development of soybean flour with improved functional and nutritional properties. Full article

Traditional cement-based foamed lightweight soils suffer from high construction costs, poor durability, and low solid waste utilization efficiency, which severely restrict their engineering application. A novel polyvinyl alcohol (PVA)-reinforced solid waste-based foamed lightweight soil is fabricated using Bayer red mud, mineral powder, and fly ash. To clarify the durability evolution mechanisms, systematic freeze–thaw cycling, long-term water immersion, and sodium sulfate erosion tests were conducted on PVA-reinforced solid waste-based, unreinforced solid waste-based, and pure cement-based specimens. The results demonstrate that the PVA-reinforced specimen achieves optimal freeze–thaw resistance with only 17.10% strength loss after 50 cycles, owing to the internal three-dimensional fiber network that restrains crack propagation and enhances matrix toughness. It also exhibits excellent long-term water immersion stability, with a mild strength increment of 4.04–10.33% after 120 days. In contrast, the CN exhibited a strength increase of 43.62%, attributed to its lower initial strength caused by incomplete hydration; however, its final strength remained between those of the other two groups. In sulfate environments, unreinforced solid waste-based specimens present superior corrosion resistance, while PVA fiber-induced interconnected pores slightly weaken sulfate erosion resistance. Microscopic analysis confirms that the generation of alunite and gypsum hydration products fundamentally causes performance discrepancies among different specimens. Different from previous studies focusing on single fiber modification or single solid waste partial replacement of cement, this study innovatively adopts a composite modification strategy of “multi-solid waste alkali-activated matrix + PVA fiber toughening”, and systematically reveals the durability evolution mechanism under multiple harsh environments. Full article

Portland cement (PC) is responsible for about 7–9% of the CO₂ emissions worldwide. Alkali-activated materials (AAMs) are alternatives that have been intensely researched in recent decades, but some of their characteristics have hindered their extensive use in construction. Hybrid cements (HCs) and limestone calcined clay cements (LC³-50) are other, more innovative alternatives to PC, which seem easier to implement. Nowadays, there is active research about them, and pioneering studies about the durability of carbon steel reinforcements with these two types of binders are beginning to be published. In this review, the properties of HC and LC³-50 are briefly summarized and related with those of PC and AAMs. The uncertainties implied by using carbonation and chloride diffusion tests designed for PC to compare materials with different compositions are discussed. Using electrochemical methods seems logical to obtain full information about the durability of reinforcements in the innovative binders. However, these alternative binders have special features that can sometimes make the traditional electrochemical approach used yield misleading results. Factors such as the high resistivity some alternative mortars can exhibit, or the possible development of redox processes in the binder due to the nature of the precursors, must be borne in mind. Full article

Reclaiming coastal saline–alkali land is important for food security, yet little is known about how irrigation and biochar jointly affect the fate of fertilizer nitrogen in these soils. Using ¹⁵N isotope tracing, this field experiment tracked the distribution and recovery of labeled fertilizer in a soil–sunflower system under three irrigation quotas (8, 16, and 24 mm per event, applied every 10 days) and four biochar rates (0, 3, 5, and 7 t·ha⁻¹). After harvest, approximately 73% of residual ¹⁵N remained in the 0–40 cm topsoil, with organic-bound N as the dominant fraction (72–74%). Mineral ¹⁵N increased with soil depth, indicating downward movement with water flow. Within sunflower plants, labeled N accumulation followed the order flower head > stem > leaf > root, with heads containing 11–12 times more ¹⁵N than roots, confirming active transport to reproductive organs. Overall ¹⁵N use efficiency ranged from 18.8% to 24.9% across treatments. Increasing biochar rate enhanced ¹⁵NUE by up to 28.2% under the same irrigation regime, whereas raising irrigation from 16 mm to 24 mm reduced ¹⁵NUE by 3.2–3.8%. Mass balance analysis showed that moderate irrigation (16 mm) combined with high biochar (7 t·ha⁻¹) achieved the highest plant ¹⁵N recovery (24.9%), maintained 70.0% of labeled N in soil, and limited unaccounted ¹⁵N to only 5.1%. These findings demonstrate that integrated water–biochar management can optimize fertilizer N retention and crop uptake in coastal saline–alkali soils, providing a scientific basis for precision fertilization in these degraded lands. Full article

Excessive N application in Camellia oleifera plantations exacerbates soil acidification and N₂O emissions, intensified by the input of Al-accumulating litter. Biochar is a promising amendment, yet how litter decomposition interacts with N and biochar to modulate acidification and greenhouse gas emissions remains unclear. To understand how decomposition of Al-accumulating litter interacts with N and biochar in the soil acidification process and gas emissions, a twelve-month laboratory incubation study was conducted using a fully factorial, three-factor completely randomized design to examine litter decomposition. The experimental factors included nitrogen fertilization, biochar amendment, and litter input level. The results showed that litter transiently activated biochar alkalinity, raising pH to 5.7–6.3, but subsequent organic acid release drove sustained re-acidification (ΔpH −0.4 to −0.5). This pH trajectory controlled denitrification: early high pH favored complete denitrification (nosZ > nirK), while later acidification inhibited N₂O reductase, boosting N₂O emissions under single litter and N. Litter-C primed native soil organic carbon, doubling cumulative CO₂ emissions. Biochar further elevated CO₂ emission rate by 7.6% under double litter input treatment via porous-microsite priming. These results demonstrated that litter quantity dictates a temporal switch from biochar alkali activation to organic acid overrun, creating an acid rebound that amplifies N₂O while sustaining CO₂ release. Optimizing litter retention and biochar application timing is essential to break the acid-N₂O feedback in intensively managed C. oleifera systems. Full article

Alkali-activated mortars (AAMs) have emerged as sustainable alternatives to conventional hydraulic cement (HC) matrices produced with natural sand. In this context, interest in the valorization of industrial by-products to develop eco-efficient construction materials has gained crucial academic and industrial attention. This study investigates the feasibility of producing AAMs incorporating copper slag (CS) as an artificial fine aggregate (AFA) to partially or completely replace natural sand. Moreover, the binder matrix was formulated using 80% CS and 20% HC as precursors, activated with different alkaline solutions (Na₂SiO₃ + NaOH) at activator-to-precursor mass ratios ranging from 0.15 to 0.35. Concurrently, CS was incorporated as AFA at volumetric replacement levels of 0%, 25%, 50%, 75%, and 100%. The AAMs were evaluated in terms of workability, physical performance (i.e., bulk density, water absorption, and void content), and mechanical performance. The results demonstrate that the workability of the AAMs increased with higher AFA dosages, reaching a maximum improvement of 23.8% compared with the AAM without AFA. The bulk density of the AAMs increased monotonically with increasing AFA content (consistent with the higher density of AFA with respect to natural sand), whereas water absorption and void content decreased progressively. Although all AAMs exhibited significantly lower compressive strengths than M1 at 7 and 28 days, the differences progressively decreased with curing age. At 56 and 90 days, M5 and M6, incorporating 75% and 100% AFA, respectively, achieved mean compressive strengths that were not statistically different from those of M1, indicating that the mixtures with the highest AFA contents maintained later-age mechanical performance within the variability of the conventional reference mortar. The study demonstrates the feasibility of the synergistic utilization of CS as both precursor and AFA in AAMs. This dual-pathway valorization closes materials loops and advances circular economy principles within the construction sector. Full article

Quercetin is a nutraceutical flavonoid whose aqueous use is limited by poor solubility and chemical instability. Existing polysaccharide carriers may require chemical modification, crosslinkers, multicomponent formulations, or complex processing. Here, alkali-neutralization-induced β-1,3-1,6-glucan nanoparticles (r-glucan NPs), prepared from Aureobasidium pullulans K-1 glucan, were compared with β-cyclodextrin (β-CD), using native t-glucan as a composition-matched control. Spectroscopic analyses supported quercetin association with chiral, cavity-rich domains of r-glucan NPs. r-Glucan NPs showed higher quercetin loading than β-CD and increased apparent aqueous solubility/dispersibility to 1620 ± 15.3 µM, compared with 256 ± 0.52 µM for the native β-1,3-1,6-glucan control, 347 ± 16.4 µM for β-CD, and 7.11 ± 3.97 µM for free quercetin. The t-glucan control initially retained quercetin but showed limited aqueous dispersibility and formed a visible precipitate within 3 days in 1 vol% ethanol. Although carrier association reduced oxygen radical absorbance capacity (ORAC) activity on an equal-quercetin basis, r-glucan NPs yielded a maximum ORAC value of 11,600 ± 1200 µmol TE L⁻¹, compared with 815 ± 235 for β-CD and 368 ± 38.2 for free quercetin. r-Glucan NPs also improved apparent retention, photostability, stability at pH 6.8, and cellular antioxidant activity relative to free quercetin. These results support r-glucan NPs as food-compatible carriers for aqueous quercetin delivery. Full article

Biotic stresses (pest feeding, pathogenic fungal/bacterial/viral infection) and diverse abiotic stresses (extreme temperature, drought, waterlogging, saline–alkali soil, heavy metal pollution, nutrient deficiency, UV-B, ozone) severely restrict crop growth and global agricultural yield. Lipids act as core membrane structural constituents and vital secondary signaling messengers, executing multi-layered adaptive balancing functions during cell-type interactive stress acclimation, rather than uniform whole-plant lipid responses. They sustain membrane structural integrity across distinct cell populations, serve as synthetic precursors of bioactive signaling molecules, and trigger cascaded transcriptional and metabolic reprogramming upon environmental stimuli to rebalance physiological status among different cell types. This review systematically summarizes cell-type interactive lipid-mediated plant defense and acclimation balance mechanisms across biotic and abiotic stress contexts. We elaborate the biological functions of fatty acids, phospholipids, galactolipids, sphingolipids and their derivatives (jasmonate, salicylic acid, phosphatidic acid, oxylipin) in stress signal transduction and antioxidant defense and strictly distinguish two categories of lipid changes under all stress types: active adaptive lipid remodeling and passive stress-induced lipid oxidative damage. Key contents include stress-triggered cell-type-specific membrane lipid remodeling, the hierarchical transcriptional regulatory network mediated by WRI1, LEC1, PHR, MADS and other transcription factors governing oil metabolism, as well as crosstalk between lipid metabolism and compartmentalized reactive oxygen species (reactive oxygen species (ROS)) signaling. We further compare conserved lipid-regulatory modules and species-specific divergent responses across model plants and economic oilseed crops, integrating state-of-the-art targeted/untargeted lipidomics, single-cell spatial lipidomics and multi-omics joint breeding strategies to improve multi-stress tolerance in oilseed crops. By consolidating global research progress up to 2025, including the two latest 2026 cross-species meta-analysis reviews, this review provides systematic theoretical support and operable multi-level technical frameworks for genetic engineering targeting conserved lipid pathways to breed stress-resilient high-oil crop germplasm, and highlights reliable lipid stress biomarker screening as a promising translational research direction. Full article

High-temperature chlorination roasting is a critical technique for achieving ultra-high-purity quartz required in semiconductor, photovoltaic, and fiber-optic applications. However, the removal mechanisms of lattice-bound impurities remain poorly understood due to a lack of integrated thermodynamic and kinetic analysis. This study systematically investigates the removal behavior of seven key lattice impurities, namely Ti, Al, B, Fe, Li, Na, and K, during chlorination roasting using combined thermodynamic modeling and diffusion kinetics. Thermodynamic calculations reveal that carbonaceous reductants are indispensable for enabling spontaneous chlorination of substitutional impurities such as Ti, Al, and B, while alkali metals including Na, K, and Li can be effectively removed under HCl atmosphere at moderate temperatures. Kinetic analysis identifies solid-state diffusion through the SiO₂ lattice as the likely rate-determining step based on the modeling framework, with activation energies ranging from approximately 90 kJ/mol for Na⁺ to 400 kJ/mol for Ti⁴⁺. A significant diffusion crossover effect is observed, where high-activation-energy impurities exhibit exponential mobility gains above 1200 °C. An alkali-first, Al-follows coupled diffusion mechanism is elucidated for aluminum removal. Based on these findings, a temperature-staged, atmosphere-segmented roasting strategy is proposed. This work provides a quantitative mechanistic framework for deep impurity removal and offers practical guidance for overcoming the 4N8 purity bottleneck in high-purity quartz production. Full article