Search Results (133)

The consumption of concrete is enormous during coal mine construction in the Xinjie Taigemiao mining area. During the concrete production process, the cleaning of concrete tank trucks and mixer equipment generates a large amount of waste sludge separated from fresh concrete. How to successfully recycle waste sludge has become a key issue that urgently needs to be solved in mine construction. In this work, a method is proposed for reactivating waste sludge into cementitious materials by wet grinding to peel off hydration products from the surface of cement particles, and the influence of aging time and wet-grinding time on the mechanical properties and frost resistance of reactivated waste sludge paste are investigated; furthermore, through testing methods such as hydration heat analysis, XRD, and SEM, the hydration and hardening mechanisms of waste sludge treated by wet grinding are analyzed. The results show that wet grinding can break the adhesion between agglomerated waste particles and peel off the hydration products from the surface of the waste particles to obtain fresh cement particles, thereby restoring the cement’s hydration activity and bonding properties. The cementitious properties of reactivated waste sludge first increase and then decrease with the increase in aging time, and they first increase and then tend to stabilize with the increase in wet-grinding time; the frost resistance of the reactivated waste sludge is improved. The optimal aging time and optimal wet-grinding time for reactivated waste sludge are 14–18 h and 10 min, respectively. Full article

The study evaluated the potential of low-dose foliar melatonin (MT) treatments to alleviate chilling injury in cucumber plants, with a particular focus on mimicking sudden spring frosts in open-field cultivation. Cucumber seedlings were sprayed with MT solutions at 0.1, 1, and 10 mg L⁻¹ (0.4, 4, 40 µM respectively), then subjected to a controlled chilling regime (4 °C for 72 h). A set of biochemical and physiological parameters was assessed, including stem elongation, leaf area, tissue water content, photosynthetic pigment concentrations, malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) accumulation, antioxidant enzyme activities, and soluble carbohydrate profiles. In addition, the thermostable fraction of chlorophylls a and b was determined as an indicator of photosynthetic system integrity; this parameter substantially increased under MT treatment, particularly at 1 and 10 mg L⁻¹, despite an overall reduction in total pigment content. The results demonstrated that MT pretreatment, especially at 1 mg L⁻¹, significantly mitigated chilling-induced growth inhibition, preserved chloroplast integrity, and reduced membrane lipid peroxidation. Moreover, MT promoted the accumulation of osmo- and cryoprotective sugars, contributing to improved cellular homeostasis under low temperature. These key findings indicate that low-dose MT priming is a promising, nature-derived strategy to enhance the tolerance of cucumber to acute chilling events, supporting the development of sustainable and organic-friendly approaches for spring frost protection. Full article

To promote the high-value utilization of industrial solid waste and enhance the durability of construction materials in cold regions, this study investigates an autoclaved aerated concrete (AAC) system prepared primarily with fly ash and oil shale residue, with a particular focus on its frost resistance. The physical and chemical properties of the raw materials were characterized using X-ray fluorescence (XRF) and X-ray diffraction (XRD) to optimize the pore structure and mineral composition. A systematic evaluation of 15 continuous freeze–thaw cycles was conducted, comprehensively analyzing the compressive strength retention, mass loss rate, and thermal conductivity. The experimental results indicate that a 50% replacement of fly ash with oil shale residue, combined with an optimized water-to-binder ratio (0.66), significantly improves the pore uniformity and skeleton stability of the AAC. The optimized mixture (YYY50W) achieved a compressive strength of 5.2 MPa and a low thermal conductivity of 0.1654 W/(m·K). After 15 freeze–thaw cycles, the mass loss was minimal (<3 g), and the compressive strength retention rate ($R$) reached 90.0%, demonstrating superior frost resistance. This study elucidates the microstructural mechanism by which oil shale residue promotes the formation of low-crystallinity tobermorite and C-S-H gels, providing potential experimental evidence for the utilization of industrial by-products in building materials for cold environments. Full article

Frost damage to reproductive tissues is a major constraint to stable yield in ‘Hass’ avocado (Persea americana Mill.) orchards, yet practical protected-cultivation strategies for mature trees remain limited. While shading nets are widely used to mitigate heat stress, their potential to reduce frost damage in mature, bearing avocado trees remains insufficiently understood. We evaluated the effects of winter deployment of high-density (60%) silver shading nets on microclimate, physiological performance, and productivity of mature ‘Hass’ avocado trees over two consecutive winters. During a severe frost event (minimum −3.5 °C; approximately 11 h below 0 °C), shading nets had little effect on minimum nighttime temperatures but reduced daytime solar irradiance and maximum temperatures. Following the frost event, control trees suffered extensive vegetative and reproductive damage, whereas net-covered trees exhibited substantially lower injury, with floral bud damage declining from 80% to 22%. Net-covered trees exhibited significantly higher maximum quantum efficiency of photosystem II (Fv/Fm; 0.74 vs. 0.48 in control trees). These responses were associated with greater flowering intensity and, in a within-year comparison following the severe frost event, a significant yield advantage in the subsequent season (16 vs. 0.4 kg tree⁻¹). In contrast, no statistically significant treatment differences were detected during a frost-free winter. These findings indicate that winter deployment of shading nets may help sustain reproductive performance in mature avocado trees following severe frost events, although this interpretation is based on a single frost-affected season and requires validation across additional frost events. Full article

Frost prediction in tropical high-mountain agricultural regions is difficult because sparse meteorological networks must represent strong terrain-driven microclimatic variability. This article presents a topoclimatic graph dataset for frost prediction in the Altiplano Cundiboyacense, Colombia. The released core dataset contains 23 agricultural weather stations and is seasonally focused on recurrent November–February frost periods rather than year-round continuous monitoring. It includes four consistently available meteorological variables at 30 min resolution: air temperature, relative humidity, dew point temperature, and solar radiation. The data were consolidated from multiple operational sources, harmonized to a common temporal grid, subjected to physical and consistency-based quality control, and completed through temporal and spatial reconstruction with traceability labels. The final release also provides binary frost_event and frost_warning_6h labels, point-based topographic descriptors, 1 km buffer-based raster summaries, land-cover proportions, station-level static feature vectors, and graph products including edge lists and adjacency matrices. These data products support graph-based deep learning, multimodal spatiotemporal analysis, and frost early warning experiments in a tropical mountain agroecosystem. The dataset offers a reproducible framework for integrating heterogeneous environmental observations into graph-ready representations while preserving sufficient environmental context for benchmarking frost prediction methods in data-sparse regions. Full article

Perennial wild relatives of annual crops possess traits associated with stress tolerance, efficient nutrient uptake, and increased soil carbon sequestration. They therefore represent valuable genetic resources for developing perennial crops that may reduce environmental and climate impacts and enhance food security. We evaluated 151 introgression lines (ILs) derived from crosses between barley and the perennial relative Hordeum bulbosum, each carrying unique H. bulbosum chromosome segments in a barley genetic background. Growth and regrowth after harvest were evaluated in two field trials, established by spring and fall planting in separate years in central Sweden, and under simulated two-year seasonal cycles in a climate chamber. In the climate chamber, 54% of the ILs exhibited strong regrowth, and two-thirds of these ILs showed reproductive growth across two seasonal cycles. In the field, most ILs showed regrowth after harvest but did not survive the cold winter. The parental genetic background had a strong effect from the barley parent on several growth and reproductive traits, but some ILs exhibited phenotypes not expected based on the barley parent. Of the divergent ILs with high regrowth, identified by PCA combining all studied traits, H. bulbosum introgressions at chromosome arms 2HL and 4HL were highly represented among ILs with cultivar Emir as a barley parent, and introgressions at 1HL among ILs with cultivar Morex as a parent. Perennial growth was observed only under mild conditions, indicating that perenniality of these ILs in a cold-temperate climate requires not only regrowth capacity but also adaptation to photoperiod, vernalization, and frost. ILs with high regrowth and reproductive growth may be used in crossing efforts with cold-tolerant germplasm to support the development of perennial barley. Full article

Ulluco (Ullucus tuberosus), the second most economically important Andean tuber after potato, has been cultivated for over 5500 years. Despite its resistance to frost, drought, and high altitudes, as well as its biochemically complex profile, ulluco remains underrepresented in the scientific literature and absent from international markets. This comparative review synthesises the evidence available up to November 2025 regarding its biology, nutritional profile, phytochemistry, and food industry applications relative to four other Andean tubers: oca (Oxalis tuberosa), mashua (Tropaeolum tuberosum), native potato (Solanum tuberosum L.), and yacon (Smallanthus sonchifolius). The main comparative findings are as follows: First, ulluco is the only Andean tuber that biosynthesises betalains instead of anthocyanins, producing up to 32 distinct compounds that are stable across a pH range of 3–7, a chromatic stability advantage over anthocyanin-based pigments from mashua, oca, and native potato, which suggests its potential as a source for the development of clean-label natural colourants. Second, among the five species evaluated, ulluco protein content across different morphotypes ranges from 5.60 to 15.7 g/100 g dry weight, ranking within the upper range of values reported for mashua and oca, and comparable to or higher than the upper ranges reported for native potato and yacon. This variability reflects the genotypic and ecogeographical diversity of the evaluated accessions and is not a methodological inconsistency, with 20% of varieties exceeding 10 g/100 g and providing six essential amino acids, supporting genetic improvement programmes aimed at nutritional security. Third, ulluco starch exhibits a low gelatinisation temperature (56–60 °C), a high amylose content (24–36%), and pseudoplastic behaviour, properties comparable or superior to potato starch for specific applications, with technical viability validated at a laboratory scale in applications including biodegradable films, food 3D printing inks, and dehydrated snacks. Unlike yacon, which accumulates fructooligosaccharides and lacks starch, ulluco aligns with oca, mashua, and potato as a starch-accumulating species. Critical gaps identified include the absence of clinical evidence on betalain bioavailability, the lack of a complete nuclear genome assembly, and the non-existence of standardised processing methods for industrial scaling. A coordinated agenda that integrates clean seed programmes, pilot-scale validation, and genomic breeding is essential for the bioeconomy of the 21st century to transform ulluco into a high-value ingredient. Full article

Geopolymer concrete contains inorganic aluminosilicate polymer gels formed through the activation of industrial solid wastes. This study investigated the effects of fly ash (FA) and silica fume (SF) on the durability and microstructure of geopolymer concrete exposed to freeze–thaw cycles and single-side salt erosion. Five mixtures were prepared using Baioheng geopolymer cement, with FA replacement levels of 15% and 25% and SF replacement levels of 3% and 5%. Mechanical tests, freeze–thaw tests, single-side salt-freezing tests, SEM-EDS, XRD, and CT analysis were conducted to evaluate the relationship between macroscopic performance and inorganic polymer gel structure. The results showed that 25% FA reduced compressive strength and freeze–thaw resistance, mainly due to insufficient reaction products and increased defect connectivity. In contrast, 3% SF improved the 56 d compressive strength by 13.24%, maintained the relative dynamic elastic modulus at 86.64% after 100 freeze–thaw cycles, and limited the mass loss to 0.72%. SEM-EDS and XRD results indicated that appropriate SF addition increased the Si/Al ratio and promoted the formation of C-(A)-S-H/N-A-S-H-related gel products, leading to a denser inorganic polymer matrix. However, excessive SF weakened the improvement effect, possibly due to local heterogeneity and dispersion difficulty. These results indicate that controlling the composition and spatial distribution of inorganic aluminosilicate polymer gels is essential for improving the salt-frost durability of geopolymer concrete. Full article

Dredging projects associated with China’s expanding maritime transportation and waterway regulation produce substantial volumes of dredged soil each year. This dredged soil, characterized by poor engineering properties, cannot be directly used for filling projects and requires improvement. On the other hand, the use of solid waste curing agents to replace traditional curing agents for semi-curing improved dredged soil can achieve the goal of treating waste with waste. This study employs a CGF curing agent composed of calcium carbide slag, blast furnace slag, and fly ash for the semi-curing improvement of dredged soil. The impact of the curing agent content on the compaction properties of semi-cured improved dredged soil is investigated. Additionally, through freeze–thaw cycle tests and microscopic experiments, the influence of the number of freeze–thaw cycles on the strength of semi-cured improved dredged soil and its microscopic mechanism are examined. The results indicate that as the curing agent content increases, the maximum dry density of the CGF semi-cured improved dredged soil decreases, while the optimal moisture content increases. Under freeze–thaw cycles, both the mass and unconfined compressive strength of the CGF semi-cured improved dredged soil decrease with an increasing number of cycles. Microscopic test results show that alkali-activated products (C-S-H, C-A-S-H, C-A-H) cement soil particles, fill soil pores, and enhance the internal stability of the soil. However, as freeze–thaw cycles progress, the structure of the CGF semi-cured improved dredged soil is gradually damaged. The enlargement of pores and the formation of penetrating cracks and voids lead to a reduction in strength. Increasing the curing agent content can effectively improve the frost resistance of the CGF semi-cured improved dredged soil. Full article

The quality of glutinous rice flour (GRF) plays a critical role in determining the processing suitability of Tangyuan, a traditional Chinese glutinous rice-based food. This study systematically characterized the physicochemical, pasting, textural and digestive properties of twelve representative GRFs, as well as the cooking behaviors of the resulting product of Tangyuan. The results revealed that different GRFs displayed varied protein, total starch and amylopectin contents. The microstructure of Tangyuan exhibited three main types: robust and dense (e.g., H1 and H3), porous and soft (e.g., S1 and S4), and fragmented and disrupted (e.g., S2 and S3) networks. Rheological and pasting profiling revealed that doughs with extreme rigidity (G′ > 10⁴ Pa) and high setback values exhibited rapid retrogradation, leading to severe frost cracking during cold-chain storage. Tangyuan with moderate G′, loss tangent (tan δ) below 0.35, and balanced peak viscosities provided optimal viscoelasticity for both mechanical machinability and freeze–thaw stability. Furthermore, S5 with naturally high resistant starch contents significantly attenuated the hydrolysis index, successfully shifting Tangyuan from a high-glycemic to a medium-glycemic profile. The results provide valuable insights into the screening of raw glutinous rice flour from different origins, offering theoretical guidance for the standardized production of freeze–thaw-stable and low-glycemic functional Tangyuan. Full article

Frost buildup on copper tube-fin heat exchangers reduces their performance in cold, humid conditions. Fin length plays a key role in balancing heat transfer and frost resistance. This study experimentally examines how fin length affects thermal and frosting behavior. Four heat exchangers with fin lengths of $15.1$ $\mathrm{m}$$\mathrm{m}$, $18.53$ $\mathrm{m}$$\mathrm{m}$, $20.3$ $\mathrm{m}$$\mathrm{m}$, and $23.5$ $\mathrm{m}$$\mathrm{m}$ were tested at 2 °C/1 °C dry-bulb/wet-bulb air temperature and $-6$ °C coolant temperature under constant static pressure. Results show that longer fins increase total heat transfer—peak capacity rose from 512 $\mathrm{W}$ to 566 $\mathrm{W}$—but reduce heat transfer per unit area by about 30%. Operating time before defrosting increased by 30.6%, from $45.7$ $\min$ to $59.6$ $\min$, due to lower frost density. Total frost mass grew, but unit-area frost decreased by 12.7%. During defrosting, longer fins achieved greater absolute airflow recovery (from 195 to 213 ${\mathrm{m}}^3$h⁻¹), though defrosting efficiency per gram of frost declined. Short fins (15 $\mathrm{m}$$\mathrm{m}$) suit space-limited systems needing high surface efficiency. Long fins (23 $\mathrm{m}$$\mathrm{m}$) benefit large systems requiring long run times and strong post-defrost performance. Medium lengths (17 $\mathrm{m}$$\mathrm{m}$ to 20 $\mathrm{m}$$\mathrm{m}$) offer a practical balance for general use. These findings support better heat exchanger design in frost-prone applications. Full article

Michelia compressa, a member of the Magnoliaceae family, is an evergreen tree of considerable significance in both landscape gardening and industrial production. However, during its introduction to northern subtropical regions in China, this species often suffers from frost damage, which limits its widespread application. The utilization of housekeeping genes is essential when performing gene family analyses under abiotic stress conditions. Additionally, auxin response factor (ARF) transcription factors (TF) play a crucial role in plant responses to abiotic stresses; however, their specific function in cold stress responses within M. compressa has not been systematically investigated. Ten housekeeping genes were selected from transcriptome data for evaluation using quantitative real-time PCR (qRT-PCR). The optimal housekeeping gene identified through screening was used for verification of gene family analysis. Additionally, key genes underwent functional validation. Analysis conducted with GeNorm, NormFinder, and BestKeeper identified 28S as the optimal reference gene for M. compressa under cold stress. Furthermore, an analysis of the ARF gene family using full-length transcriptome data revealed a total of 48 McoARF genes, which clustered into three groups alongside the Arabidopsis thaliana ARFs. Among these, eight selected McoARF genes exhibited significantly elevated expression levels in leaves under cold stress and demonstrated tissue specificity. Functional validation revealed that transgenic plants overexpressing McoARF13 displayed elevated levels of reactive oxygen species (ROS), hydrogen peroxide (H₂O₂), and malondialdehyde (MDA), as well as increased activities of peroxidase (POD) and superoxide dismutase (SOD) in leaves under cold stress. This study represents the inaugural screening of housekeeping genes in M. compressa under cold stress conditions, accompanied by an analysis of the ARF gene family. The functional validation of McoARF13 was successfully conducted, offering valuable insights into the molecular mechanisms that underlie cold stress response in M. compressa. Full article

Due to the high water absorption of coal gangue aggregate, concrete prepared with a high content of this material exhibits a significantly reduced service life under freeze–thaw conditions. This study evaluates the frost resistance of gel-enhanced coal gangue aggregate concrete modified by incorporating nano-SiO₂ and polypropylene fibre (PPF) to generate more C-S-H gel and form a dense structure with different dosages of air-entraining agent (0, 0.004%, 0.008%, 0.012%, and 0.016%). The research results show that when the admixture content is 0.012%, the concrete still exhibits excellent frost resistance after 100 freeze–thaw cycles. The mass loss is only 4.7%, compressive strength loss is 37%, and dynamic elastic modulus loss is 39%, while the specimen maintains the best apparent integrity. In addition, the capillary water absorption rate, initial capillary water absorption rate, and cumulative water absorption all reach their lowest values under this condition, indicating optimal frost resistance performance. Finally, through regression analysis, a highly accurate predictive model for capillary water absorption was established, providing a theoretical basis for further research on the durability and frost resistance of coal gangue aggregate concrete. Full article

Alkali-activated solid waste-based geopolymer represents a novel form of inorganic cementitious material, which is one of the key research directions in the building materials field to achieve the targets of carbon peak and carbon neutrality. Therefore, taking solid waste materials as raw materials to prepare the alkali-activated solid waste-based geopolymers with better mechanical properties is of significant importance for expanding the utilization channels of industrial solid waste materials in Hebei Province. In this study, three solid waste materials, slag, iron tailings sand and coal gangue powder, were used as the precursors of geopolymer, and solid sodium silicate was used as the activator to prepare the solid waste-based geopolymer. Response surface methodology was adopted to design the composition of the geopolymer, and the dosages of slag, Na₂O and coal gangue powder were taken as design variables, and the compressive strength of the geopolymer at 7 days and 28 days were taken as response variables. The results show that it is feasible to optimize the composition of solid sodium silicate-activated solid waste-based geopolymer (SSG) by using response surface methodology. The error value of the SSG-mortar compressive strength prediction model is below 2.0%. The slag contents exhibit a positive correlation with the compressive strength of SSG-mortar, but the coal gangue powder contents and Na₂O contents have a negative correlation. The optimized compositions of SSG-mortar are 20% iron tailings sand, 26% coal gangue powder, 54% slag, and 6.41% Na₂O (regulated by 6.23% solid sodium silicate and 6.23% solid NaOH granules), and the corresponding compressive strengths of SSG-mortar at 7 days and 28 days are 37.1 MPa and 44.9 MPa, respectively. In addition, dry shrinkage tests, wet–dry cycling tests, freeze–thaw cycling tests, salt corrosion tests, SEM analysis and XRD analysis were conducted on the SSG-mortar with the optimal composition to evaluate its shrinkage behavior, freeze–thaw resistance, salt corrosion resistance and microstructural strengthening mechanisms. The results show that SSG-mortar has relatively good frost resistance and salt erosion resistance. The mass loss rate value and compressive strength loss rate value of SSG-mortar are 1.67% and 18.7%, respectively, after 100 freeze–thaw cycles. Furthermore, the corrosion resistance coefficient value of SSG-mortar is greater than 92%, and the mass loss rate value is lower than 2.4%. The SEM and XRD test results display that, in an alkaline environment, the interwoven consolidation of hydrated gels (including C-S-H gel, C-A-S-H gel, C-(N)-A-S-H gel and N-A-S-H gel) and the filling effect of solid wastes jointly achieve an improvement in the properties of SSG-mortar. Full article

Solar greenhouses are indispensable infrastructure for winter vegetable production in high-latitude regions, maintaining favorable growing conditions without auxiliary heating through superior thermal insulation and solar radiation capture. However, extreme meteorological events disrupt this equilibrium, and soil temperature prediction remains challenging due to thermal hysteresis—time-lagged responses to environmental drivers that threaten crop viability during pre-dawn periods. Existing studies focus on air temperature or short-term horizons (3–6 h), leaving the critical 12 h prediction window inadequately addressed. This study develops a hybrid machine learning framework for 12 h soil temperature prediction in a solar greenhouse. High-resolution data were collected using soil temperature sensors at 200 mm depth (tomato root zone) during the winter growing season. Five algorithms were evaluated: RF and XGBoost (Bagging/Boosting for trend/residual capture), LSTM and GRU (temporal memory), and a novel RF-XGBoost hybrid with two-stage residual correction. The hybrid model achieved R² = 0.9927, improving standalone RF (R² = 0.9883) by 0.45% with MSE, RMSE, MAE reductions of 18.1%, 9.6%, 13.9%. Maximum 12 h error was 2.52 °C versus 3.12–4.60 °C for standalone models. The 12 h horizon enables preemptive heating activation, mitigating frost risk while avoiding unnecessary energy expenditure. Full article