Search Results (35,703)

Hydrogen (H₂) is a promising clean energy carrier with the potential to partially replace fossil fuels. Biological H₂ production using microorganisms offers an environmentally friendly alternative. The halotolerant cyanobacterium Aphanothece halophytica can produce H₂ under nitrogen-deprived and dark anaerobic conditions. In this study, a co-culture strategy was investigated to enhance H₂ production. Five bacterial strains were screened for their ability to improve H₂ production when co-cultivated with A. halophytica. Among them, Staphylococcus aureus significantly enhanced H₂ production, achieving a maximum rate of 11.11 ± 0.18 µmol H₂ g⁻¹ dry weight h⁻¹. Optimization of the bacterial partner revealed that S. aureus cells harvested at 12 h in the mid-logarithmic phase with an OD₆₀₀ of 4.0 were the most effective. An inoculum ratio of A. halophytica to S. aureus of 4:1 further enhanced H₂ production, increased bidirectional hydrogenase activity, and reduced O₂ accumulation. Under optimal conditions (0.945 mmol C-atom L⁻¹ glucose, 0.25 M NaCl, pH 7.4, and 35 °C), the maximum H₂ production rate reached 132.49 ± 4.45 µmol H₂ g⁻¹ dry weight h⁻¹, approximately 5.5-fold higher than that under normal conditions. The co-culture achieved a cumulative H₂ yield of 3248.51 ± 88.11 µmol H₂ g⁻¹ dry weight after 48 h. Full article

The present study aimed to assess whether postmortem analysis of aqueous humor in pigs can be used to estimate antemortem serum biochemical values. The experimental design used a control group to establish regression equations linking postmortem aqueous humor to antemortem serum biochemical values. These models enabled reconstruction of the physiological status in decomposed forensic cases associated with heatstroke and hypoxia in pigs that died following a ventilation system failure on a commercial farm, and assessment of physiological distress, cause of death, and potential intentional animal abuse. Concentrations of albumin (ALB), alkaline phosphatase (ALP), alanine aminotransferase (ALT), amylase (AMY), total bilirubin (TBIL), urea nitrogen (UN), creatinine (CRE), calcium (Ca), phosphate (PHOS), sodium (Na), potassium (K), glucose (GLU) and total protein (TP) were measured in aqueous humor and compared with serum samples obtained after slaughter of 30 pigs. Biochemical analyses were performed using a chemistry analyzer with commercial reagent rotors designed. Strong correlations were observed for Na, K and CRE concentrations and for ALT and UN activities between aqueous humor and serum, while TP, ALB, AMY, TBIL and Ca showed weaker associations. Notably, CRE and UN showed strong postmortem correlations with serum values in pigs, consistent with findings in cats and other species, highlighting their reliability as indicators of renal function. Electrolyte concentrations, particularly K and Na, followed consistent and well-recognized patterns described in both human and veterinary forensic studies, with K levels in pigs comparable to those observed in other domestic animals. The results indicate that postmortem aqueous humor analysis of CRE, Na, K, AST, and UN provides a reliable estimation of corresponding serum values in pigs, representing a useful diagnostic and forensic tool in the case of animal welfare. Full article

Acute kidney injury (AKI) is a frequent complication in critically ill patients and is associated with high morbidity, mortality, and an increased risk of progression to chronic kidney disease (CKD). In this context, nutritional management represents a key component of supportive therapy, as AKI is commonly characterized by hypercatabolism, negative nitrogen balance, and protein-energy wasting. Current nutritional strategies primarily focus on the quantity of protein intake required to compensate for catabolic losses, particularly in patients undergoing renal replacement therapy (RRT). However, growing evidence suggests that the quality and metabolic effects of dietary protein sources may also influence renal physiology and recovery. Plant-based proteins have recently gained attention as a potentially advantageous nutritional strategy in kidney disease. Compared with animal-derived proteins, plant-based proteins are associated with a lower dietary acid load, reduced production of gut-derived uremic toxins, and beneficial effects on the intestinal microbiota. In addition, their amino acid profile may modulate oxidative stress, inflammatory pathways, and renal hemodynamics. These characteristics may contribute to a more favorable metabolic environment in patients with AKI, potentially supporting renal recovery and reducing the risk of AKI-to-CKD transition. This review examines the pathophysiological mechanisms linking protein metabolism, renal injury, and nutritional support in AKI. Particular attention is given to the role of plant-based proteins, their amino acid composition, and their potential nephroprotective effects. Understanding the interaction between dietary protein sources, metabolic pathways, and the gut–kidney axis may help guide future nutritional strategies aimed at improving outcomes in critically ill patients with AKI. Full article

Nymphaea candida Presl is a rare and endangered waterlily species, and cultivating robust seedlings suitable for artificial propagation has become a critical issue for the conservation of this species. In this study, Aspergillus sp., an endophytic fungus isolated from the roots of N. candida, showed the capability of solubilizing phosphate and potassium and producing siderophores. The application of Aspergillus sp. significantly increased leaf length, leaf width, leaf number, and root length of N. candida seedlings by 97.83%, 131.37%, 94.12%, and 171.25%, respectively. Meanwhile, Aspergillus sp. application significantly enhanced soil organic matter content, alkali-hydrolyzable nitrogen content, sucrase activity, and peroxidase activity by 6.57%, 31.62%, 23.26%, and 7.53%, respectively. Moreover, Aspergillus sp. enriched beneficial microorganisms including Cyanobium, Aquicella, and Cryptomycota to form a more stable rhizosphere soil microenvironment. Additionally, Aspergillus sp. upregulated genes involved in photosynthesis and photosynthesis–antenna protein pathways in N. candida leaves, with the expression levels of psbA, petG, and psbH significantly increasing by 2.17, 4.48, and 0.28-fold, respectively. Therefore, the endophytic fungus Aspergillus sp. might be a reliable tool for the propagation of N. candida seedlings, which would be helpful for the conservation of this rare and endangered aquatic plant species. Full article

Nanoparticles (NPs) have great potential for stimulating plant growth and development, reducing the negative impact of various types of stress on plants, and increasing the yield of agriculturally important crops. Metal oxide NPs (MONPs) have been shown to have a significant effect on the physiological and biochemical processes in plants, enhancing plant resilience. Among them, CuO, Mn_xO_x, and ZnO NPs are of particular interest because they contain elements essential for plant function. However, widespread use in agrochemistry and plant protection requires a preliminary risk assessment due to their potential phytotoxic effects. Phytotoxicity manifests through the development of oxidative stress, genotoxicity, and transcriptional disruption. A decrease in plant growth and photosynthesis, increased lipid peroxidation (LPO), and the accumulation of toxic NPs in plant tissues were also observed. Among the studied MONPs, CuO and ZnO NPs exhibit the greatest phytotoxic effects. However, the effects of MONPs are dose-dependent. Numerous studies have shown that MONPs can stimulate plant biometric parameters and productivity, as well as influence biochemical processes. MONPs have been shown to influence the functioning of the plant antioxidant system, manifested by modulating the content of reactive oxygen species (ROS), the activity of antioxidant enzymes (AOEs), and the regulation of signaling pathways mediated by ROS and reactive nitrogen species. Furthermore, MONPs influence the accumulation of proline and phenols in plant tissues. MONPs have a pronounced effect on the functioning of the plant photosynthetic apparatus, manifested by changes in pigment content, the activity of photosynthetic enzymes, and the functioning of photosystems. MONPs can improve nutrient absorption, regulate osmotic balance, and activate plant defense mechanisms. ZnO NPs are effective in mitigating salt stress. CuO and Mn_xO_x NPs have shown promise in mitigating biotic stress. Furthermore, these NPs were found to reduce the toxicity of heavy metals to plants. Overall, when used wisely, MONPs hold promise for enhancing the physiological, biochemical, and agronomic performance of crop plants under conditions of global climate change, effectively addressing food security issues. Full article

Silica aerogels are ideal candidates for gas adsorption due to their exceptional porosity and high specific surface area; however, the inherent mechanical fragility of their skeletal framework significantly compromises their operational stability in engineering applications. While the incorporation of carbon nanomaterials effectively enhances the mechanical robustness of aerogels, the specific microscopic mechanisms by which filler microstructure and surface chemistry dictate gas adsorption behavior remain insufficiently understood. In this study, we employed all-atom molecular dynamics (MD) simulations to develop a model of silicon-based porous composites synergistically doped with carbon nanotubes (CNTs) and graphene. The adsorption and diffusion characteristics of nitrogen (N₂) were systematically investigated across a CNT doping concentration range of 5% to 20%, and the influence of surface hydrophilicity/hydrophobicity on adsorption performance was quantitatively analyzed by modulating potential energy parameters. Our results demonstrate that the introduction of CNTs reconfigures the porous architecture, leading to an approximately 18.25% increase in the normalized specific surface area, which subsequently drives a 15% enhancement in the overall adsorption capacity of the composite. Nevertheless, analysis reveals that the weight-specific adsorption efficiency of the CNT component itself exhibits a declining trend as the doping concentration increases. This phenomenon is primarily attributed to the convex curvature of the CNTs, which restricts the effective contact area and weakens the adsorption potential, alongside the steric hindrance effects arising from local filler agglomeration at higher concentrations. Furthermore, surface chemical properties exert a significant regulatory influence on adsorption; a strongly hydrophilic modified surface (λ = 1.5) achieved an adsorption capacity approximately 98% higher than the baseline condition—an improvement that exceeds the gains provided by purely physical volume expansion. This research elucidates the synergistic mechanism between physical architecture and surface chemical modification in the adsorption process, suggesting that while the physical architecture determines the abundance of potential adsorption sites, the surface chemistry governs the actual efficiency of site utilization. These findings provide critical theoretical insights for the future design of composite aerogel materials that balance structural stability with superior adsorption performance. Full article

Nitrate (NO₃⁻) serves as a critical nitrogen source and signaling molecule essential for its growth and quality formation. Although substantial genetic variation in nitrogen use efficiency (NUE) has been documented among tea cultivars, a systematic characterization of nitrate (NO₃⁻) absorption kinetics and the associated genome-wide transcriptional regulatory networks across varying nitrate concentrations remains lacking. This study employed ¹⁵N isotope labeling and transcriptome sequencing to systematically analyze the absorption characteristics and molecular response mechanisms of the cultivars ‘Longjing 43’ and ‘Zhongming 6 hao’ under varying NO₃⁻ concentrations. Results revealed significant differentiation in absorption strategies: ‘Zhongming 6 hao’ exhibited a significantly higher absorption rate at low concentrations, whereas ‘Longjing 43’ demonstrated enhanced performance at high concentrations. Transcriptome analysis indicated that both cultivars shared coordinated regulation of ‘photosynthesis’ and ‘nitrogen metabolism’ pathways. Furthermore, 14 nitrogen metabolism genes and 64 differentially expressed transcription factors (including MYB, NAC, and LBD families) were identified. Specifically, the CsNiR gene (encoding nitrite reductase) was functionally validated; silencing of CsNiR significantly reduced nitrite reductase activity, confirming its positive regulatory role. This study provided a theoretical framework and key candidate genes for breeding nitrogen-use-efficient varieties, which is essential for sustainable tea production. Full article

Rivers emit substantial amounts of carbon dioxide (CO₂) to the atmosphere, yet its response to heavy rainfall remains unclear with intensive anthropogenic disturbances. To fill the knowledge gap, this study investigated the dynamic variability of CO₂ partial pressure (pCO₂) and CO₂ emissions flux at the Chaohu Lake Basin, a watershed under intensive anthropogenic perturbations, based on field campaigns across diverse river systems during dry season, normal season, and post-rainfall periods. Results demonstrated marked differences in aquatic pCO₂ across river types, with urban rivers (3949 µatm) exhibiting significantly higher levels than non-urban counterparts (1423 µatm). Rainfall events elevated riverine pCO₂, but the effect size varied between river types (urban river versus non-urban river). In non-urban rivers, pCO₂ following heavy rainfall (2461 μatm) was significantly higher (p < 0.05) than those observed during both dry season (1096 μatm) and normal season (712 μatm). In contrast, urban rivers demonstrated only marginal pCO₂ elevation after rainfall (20–30%). Statistical analysis revealed that discharge, total nitrogen (TN), total phosphorus (TP), and ammonia nitrogen (NH₄⁺-N) showed significantly positive correlations with pCO₂, while dissolved oxygen (DO) and pH exhibited significantly negative correlations with pCO₂. Overall, rivers in the Chaohu Lake Basin act as significant sources of atmospheric CO₂, with an annual mean CO₂ emission flux of 297.84 mmol·m⁻²·d⁻¹, and the heavy rainfall events amplify riverine CO₂ emissions (629.91 mmol·m⁻²·d⁻¹), with observed enhancement effects exceeding 300% compared to baseline conditions. To accurately estimate the CO₂ emissions from human-dominated rivers, future research should emphasize the impacts of extreme or heavy rainfall events. Full article

Microplastics (MPs) are emerging pollutants that affect soil–microbe interactions in paddy ecosystems. Periphytic biofilms (PBs) are complex microbial consortia that ubiquitously distribute at the soil–water interface of paddy ecosystems, playing essential roles in nutrient cycling and pollutant migration. However, whether MPs affect the community composition of PBs remains largely unknown. This microcosm study investigated the effects of three types of MPs (polyacrylonitrile, PAN; polyethylene, PE; and polyethylene terephthalate, PET) on the community characteristics of PBs via high-throughput sequencing (16S/18S rRNA) technology. Results showed that the addition of all MPs significantly increased the biomass and chlorophyll-a content of PBs, with PAN inducing the maximum increase (by 331.9% and 128.6%). However, all MPs had no significant effect on the PB α-diversity of bacterial and eukaryotic communities (p > 0.05). As for PB composition, PAN and PET increased the relative abundance of Cyanobacteria, Proteobacteria and Holozoa, PE increased that of Cyanobacteria, Bacteroidota and Blastocladiomycota, and all MPs decreased the relative abundance of Chloroflexi, Actinobacteriota and Basidiomycota. Furthermore, PET decreased the predicted functional potential of natural polymer degradation (cellulolysis, ligninolysis, xylanolysis, ureolysis), nitrogen fixation and nitrate ammonification, while PE increased predicted potential for plastic degradation, nitrate reduction and denitrification. Co-occurrence network analysis suggested that the PE network showed higher connectivity and lower modularity, while the PAN network showed higher modularity. This study advances our understanding of soil MPs–microbe interactions under high-concentration conditions. It also suggests that PB community characteristics may serve as potential bioindicators for soil MP pollution. Full article

Improving the effluent quality of municipal wastewater treatment plants (WWTPs) is essential for sustainable water management and water quality protection in the Yellow River Basin. Many existing WWTPs in northern China were constructed under earlier discharge requirements and now face dual challenges of stricter effluent standards and poor low-temperature performance in winter. In this study, a municipal WWTP with a design capacity of 5 × 10⁴ m³/d in northern China was upgraded to improve winter treatment performance and support stable compliance with the discharge requirements of the Yellow River Basin. The original anaerobic + oxidation ditch process suffered from unstable effluent quality, excessive sludge loading, and insufficient pollutant removal under low-temperature conditions. A land-saving retrofit strategy was therefore proposed, involving oxidation ditch wall-height raising to extend the hydraulic retention time (HRT) and membrane bioreactor (MBR) integration to increase the mixed liquor suspended solids (MLSS) concentration. After the retrofit, the total HRT increased to 19.82 h, and the average MLSS concentration reached 7050 mg/L. The relative abundances of key nitrogen-removing bacteria, including Nitrospiraceae, Nitrosomonadaceae, and Rhodocyclaceae, increased markedly. Meanwhile, denitrification sludge loading and BOD₅ sludge loading decreased to 0.030 and 0.033 kg/(kg·d), respectively. Under low-temperature conditions, the theoretical removal capacities of total nitrogen (TN) and BOD₅ reached 44.32 and 286.19 mg/L, respectively, enabling stable effluent compliance. The results show that this retrofit strategy can improve WWTP effluent quality while avoiding large-scale land expansion, providing a practical and sustainable solution for upgrading cold-region WWTPs along the Yellow River Basin. Full article

Low-temperature stress severely restricts the engineering application of anaerobic ammonia oxidation (anammox) technology in municipal mainstream wastewater treatment, leading to its slower large-scale implementation relative to industrial wastewater and reject water treatments. The inhibitory effects of low temperatures on the anammox process cannot be merely ascribed to conventional microbial metabolic responses. Elucidating the specific mechanisms underlying low-temperature impacts on anammox bacteria is therefore critical for formulating targeted mitigation strategies. In this study, a meta-analysis was performed to compare the response patterns of specific anammox activity (SAA) and nitrogen removal rate (NRR) to temperature variations. SAA declines gradually with decreasing temperature, while NRR displays a more dramatic and stepwise reduction. The T₅₀ values (temperature corresponding to 50% of the performance at 30 °C) for these two parameters are 20 °C and 15 °C, respectively. Low-temperature inhibition of anammox is a multifaceted process, encompassing direct physiological disturbances to individual anammox cells and impaired nitrite bioavailability within the microbial community. To address these temperature-related bottlenecks, a conceptual hybrid nitrogen removal system was rationally optimized by integrating conventional strategies with an innovative split-flow influent regulation strategy. This hybrid system is anticipated to enhance the stability and treatment efficiency of anammox under low-temperature conditions, thus facilitating its broader engineering application in cold climate regions. Full article

To address the limited understanding of interspecific differences in eutrophic-water remediation, six representative wetland plants—Myriophyllum spicatum, Oenanthe javanica, Zizania latifolia, Ipomoea aquatica, Iris pseudacorus, and Typha orientalis—were evaluated in a unified hydroponic system. The removal efficiencies of total nitrogen (TN), total phosphorus (TP), and ammonium nitrogen (NH₄⁺-N) were compared together with plant biomass accumulation and root-associated and fepiphytic microbial community characteristics. The results showed marked interspecific differences in growth and pollutant removal, with the M. spicatum treatment exhibiting the highest overall purification performance, achieving removal rates of 83.3% for NH₄⁺-N, 87.3% for TN, and 78.6% for TP after 42 days. Community-composition analysis suggested that the superior purification performance of M. spicatum was associated with a greater relative abundance of Proteobacteria and putative nitrogen- and phosphorus-cycling bacterial groups. By integrating a plant-free control with a side-by-side comparison of six wetland plants under identical hydroponic conditions, this study establishes a comparative framework linking nutrient removal to plant growth and microbial community assembly. Overall, M. spicatum was identified as the most promising species, providing new insight for wetland-plant selection and eutrophic-water remediation. Full article

Understanding the spatial distribution patterns and environmental drivers of plant communities is fundamental for biodiversity conservation and ecosystem management. Bombax ceiba is a widely distributed tree species that occurs in both humid tropical rainforests and drought-prone dry-hot valleys, representing two strongly contrasting ecological environments. However, the spatial patterns and environmental drivers of plant communities associated with B. ceiba across these habitats remain poorly understood. In this study, we investigated B. ceiba-associated plant communities in two representative habitats in Yunnan Province, Southwest China: a tropical rainforest in Mengla and a dry-hot valley in Yuanjiang. The species composition, community structure, and spatial coordinates of associated plants were recorded in replicated 20 m × 20 m plots. Spatial distribution patterns were analyzed using the pair-correlation function g(r), while environmental drivers were examined using Pearson correlation analysis and redundancy analysis (RDA). Species richness was substantially higher in the tropical rainforest (41 species from 33 families) than in the dry-hot valley (19 species from 14 families). Both communities contained a substantial proportion of tropical Asian floristic elements. Most dominant species exhibited aggregated spatial distributions at small spatial scales (0–7 m), indicating strong dispersal limitation and microhabitat heterogeneity. Spatial associations varied across scales: in the dry-hot valley, species associations alternated between positive and negative correlations at small scales (0–5 m) and shifted toward positive correlations at larger distances, whereas in the tropical rainforest negative associations were more common at small scales and positive associations increased at larger spatial scales. Environmental drivers differed markedly between habitats. In the dry-hot valley, community attributes were positively associated with slope, precipitation, and soil ammonium nitrogen, suggesting that community assembly is influenced by interactions between topography and water availability. In contrast, tropical rainforest communities were more strongly associated with soil phosphorus availability and temperature-related variables. These findings highlight distinct community assembly mechanisms in contrasting habitats and provide ecological insights for vegetation restoration in dry-hot valleys and biodiversity conservation in tropical rainforests. Full article

Sapling survival and growth depend on photosynthetic assimilates. Therefore, improving physiological performance during early stages may enhance subsequent performance and nursery production. This study evaluated whether exogenous oxidized glutathione (GSSG), reported to enhance photosynthesis, improves the photosynthetic, physiological, and growth-related traits of Larix gmelinii var. japonica saplings. Sixteen saplings were assigned to four treatments: GSSG, 5-aminolevulinic acid, Hyponex, and a water control. Photosynthetic, nitrogen-related, and growth traits were measured before treatment and at 3, 6, 13, and 31 days after treatment, and biomass was assessed after three months. The GSSG treatment showed no difference in the net CO₂ assimilation rate (A_max) compared with the control, but exhibited a significantly earlier peak at 6 days than the other treatments. This response was supported by the stability of GSSG-treated saplings against photoinhibition (F_v/F_m) and a tendency toward greater resilience to midday light stress (Φ_PSII). Enhanced photosynthetic performance was associated with reduced carbon and nitrogen fluctuations and was accompanied by numerically greater root and stem biomass in the 2024 terminal shoots. Although fertilization effects were generally weak and transient, GSSG elicited notable responses, suggesting that the immediate enhancement of photosynthesis underlies its impact. However, its antioxidant properties under stressful conditions warrant further investigation. Full article

Attaining uniform weld quality in the resistance spot welding (RSW) of AISI 201 stainless steel remains challenging due to the complex interdependence of process parameters and the limited understanding of shielding atmosphere effects on this lean austenitic grade. This study integrates Taguchi optimization, analysis of variance (ANOVA), and complementary trend surface visualization to evaluate the effects of welding time, current, electrode pressure, and shielding atmosphere. An L27 orthogonal array was employed, with welding current identified as the dominant parameter for both tensile strength and hardness while nitrogen shielding exhibited a significantly greater influence on hardness than on tensile force, attributable to interstitial solid solution strengthening. The optimal conditions yielded a maximum tensile force of 12.2 kN and a hardness of 353 HV, with prediction errors below 1.5% for tensile force and below 0.5% for hardness. Trend surface visualization further revealed significant current–pressure interactions governing weld quality. These findings provide a validated optimization framework for the industrial RSW of AISI 201, with direct implications for automotive and structural manufacturing. Full article