Hunan Agricultural University (Chinese: 湖南农业大学; pinyin: Húnán Nóngyè Dàxué, commonly referred to as HAU or Nongda) is a public research university located in Changsha, Hunan, China.Founded in 1951, the university was incorporated by two independent colleges under the name Hunan Agricultural College. Since Hunan was an agricultural powerhouse for the country, Mao Zedong, the founding father of the People's Republic of China, inscribed the school's name on its entrance sign. It changed to its current name in 1994.The institution began with a focus on training students in various agricultural disciplines. After more than a half century's development, the school has evolved into a renowned comprehensive university. In 1978, HAU started to award master's degrees. As of 2007, more than 50,000 students from 31 provinces across China study there, including 24,000 undergraduates, 26,000 continuing education students, 3000 graduate and doctoral students.
To address the dynamic multi-objective trade-off between economic performance and system safety in microgrid operation, this study proposes a meta-policy-guided PC-TD3-based adaptive multi-objective scheduling method for microgrids. The method uses a high-level meta-policy network to generate scheduling preferences online, while a lower-level preference-conditioned TD3 policy is trained over the full preference space so that a single model can approximate continuous economy-safety trade-offs. A two-layer safety projection mechanism is further introduced to embed local battery constraints and global voltage constraints into action execution. Long-horizon simulations based on real-world data show that PC-TD3 achieves the lowest average daily operating cost among the compared methods, at 111,405 CNY, and the lowest average number of voltage violations, at 22.1 counts/day. Across 100 test days, the cumulative economic benefit of PC-TD3 relative to the average baseline reaches approximately 0.56 million CNY. Ablation experiments further show that full-preference-space training, dynamic preference generation, and safety projection jointly improve dispatch adaptability: the complete framework maintains stable voltage responses under both normal-load and high-load scenarios, whereas removing safety projection leads to voltage violations and single-preference training weakens SOC regulation under high-load conditions. These results indicate that the proposed method can adaptively coordinate economic performance and operational safety under dynamic operating conditions, providing a practical reference for reinforcement-learning-based multi-objective microgrid dispatch.
Foliar iron delivery requires simultaneous control of ferrous-state stability, nutrient transport, and leaf-surface residence, yet these functions are rarely integrated within a single formulation. Here, we developed a carbon dot-stabilized and coordination-gated nanocarrier formulation (NFCT) by co-confining Fe2+ and carbon dots (CDs) within amino-functionalized mesoporous silica and depositing an external tannic acid-Fe (TA-Fe) coordination network. Electron spin resonance measurements and density functional theory calculations support complementary contributions of the CDs to reactive-oxygen-species attenuation and Fe2+ coordination, whereas the outer metal-phenolic network provides pH-dependent regulation of nutrient transport. Under the tested storage conditions, NFCT retained 93.0% of recoverable Fe2+ after 7 d and showed substantially greater recoverable Fe2+ availability under mildly acidic than near-neutral or alkaline conditions. On model waxy leaf surfaces, NFCT improved droplet spreading and achieved 72% of the pre-rain total-Fe deposit after a 70.7 mm simulated-rainfall challenge. These redox, transport, and interfacial attributes were associated with greater foliar Fe accumulation, chlorophyll index, biomass production, and root-system remodeling in Fe-deficient rice. In a single-site, single-season proof-of-concept field trial, no statistically significant differences were detected between NFCT and commercial EDTA-Fe for the measured agronomic traits under the tested application program. The results define a carbon-dot-centered structure-property-function framework in which internal Fe2+ protection, external coordination-gated transport, and rainfast foliar residence provide complementary delivery functions.
This study investigates the performance of the Constant Radial Stiffness Triaxial (CRST) test for simulating pavement loading conditions compared to the traditional repeated load triaxial test. Through the integration of an advanced constitutive model capable of accurately simulating cyclic hardening in unsaturated soils, a fully coupled Finite Element (FE) model for unsaturated soils is developed. This FE model enables the exploration of the effects of varying degrees of saturation on soil behaviour under a large number of load cycles, accounting for the complex interactions between the soil skeleton, pore water pressure, and suction. FE examples show how initial soil conditions like the degree of saturation and void ratio, and loading conditions, influence permanent deformations in flexible pavements. These findings can provide insights into pavement permanent deformation mechanisms and demonstrate the effectiveness of the CRST test to provide a reasonable representation of in-situ pavement loading conditions. Furthermore, the study illustrates the FE model’s utility in refining the CRST test design, particularly in determining appropriate radial stiffness values that effectively mimic the influence of surrounding soils. This aspect is vital for improving the relevance of the laboratory testing method to in-situ pavement loading scenarios.
Microplastics (MP) pollution is widespread in livestock farming environments. Exposure to MP can impair the gastrointestinal barrier, alter the structure and metabolism of the microbiota, and subsequently lead to organ damage. MP not only hinder cattle farming but also enter the food chain, posing a potential risk. Polyethylene (PE), a type of MP commonly detected in ruminant feed, has not yet been studied for its specific effects on cattle. Using calves as an animal model, this study investigates how exposure to MP induces toxicity via the rumen microbiota-gut-liver axis. Exposure to MP impaired weight gain and liver development in cattle, altered liver tissue pathology, increased blood lipopolysaccharide (LPS) levels, and triggered a systemic inflammatory response, identifying the liver as the primary target organ. Inflammation was closely associated with the dysbiosis of rumen microbiota and metabolites. MP exposure also damages the barrier integrity of the rumen, jejunum, and colon. The underlying mechanism involves MP altering the rumen microbial composition, which in turn triggers metabolic disorders, activates LPS synthesis pathways, and inhibits tight junction protein expression in the jejunum and colon. Although MP do not cause significant architectural damage to muscle tissue, they disrupt lipid homeostasis and nutrient composition, thereby promoting the deposition of pro-inflammatory LPS within muscle tissue. Rumen fluid metabolomics analysis revealed that differential metabolites were mainly enriched in the ATP-binding cassette transporter (ABC) pathway, with 4-fluoro-3-phenoxybenzoic acid and isovalerylglutamic acid being significantly correlated with levels of LPS, IL-6, TNF-α, and IL-1β. Notably, the concurrent increase in TNF-α and LPS in both the bloodstream and liver, alongside altered blood metabolomics, indicates that MP induce hepatic damage by disrupting the rumen microbiota-gut-liver axis. Transcriptomic analysis revealed that liver inflammatory injury was closely associated with NF-κB activation. Further mechanistic analysis supported the central role of the TLR4/MyD88/NF-κB signaling pathway. MP impair liver function in cattle by disrupting the rumen microbiota-gut-liver axis. This process involves the perturbation of rumen flora and intestinal barriers, triggering LPS translocation into the bloodstream, and ultimately causing liver damage.
Coastal saline soils require effective amelioration strategies to support sustainable agriculture. Biochar derived from straw is considered an eco-friendly and cost-effective soil amendment. Previous studies have demonstrated that iron-modified biochar and humic acid can promote plant growth; however, their synergistic effects in saline environments remain unclear. This study aims to develop a novel humic acid-loaded magnetic biochar and evaluate its effectiveness in improving coastal saline soil and promoting rice growth. Straw-derived biochar was modified with iron to produce iron-containing biochar (FC), followed by oxidation to obtain magnetic biochar (FO). Subsequently, activated humic acid was loaded onto FO to synthesize humic acid magnetic biochar (HAFO). The physicochemical properties of the materials were characterized, and a pot experiment was conducted to assess their effects on soil properties and rice growth. Pyrolysis and oxidation successfully loaded nano-Fe₃O₄ onto biochar and reduced particle size to the submicron level. The incorporation of humic acid further enhanced the functionality of iron-modified biochar by increasing surface oxygen-containing functional groups and nutrient availability. Soil organic matter content, cation exchange capacity, salinity, and nutrient levels significantly influenced rice growth (p 0.05). Biochar application alleviated salt stress by improving soil properties, thereby promoting rice growth and development. The performance of biochar in improving coastal saline soil and enhancing rice growth is largely dependent on its intrinsic properties. The HAFO developed in this study is an economical and efficient soil amendment with significant potential for improving saline soils and contributing to global food security.
