Search Results (517)

Soil microbial functional potential is crucial to maintaining forest productivity and ecosystem functions. However, how microbially mediated soil nutrient cycling responds to environmental changes, particularly those caused by variations in elevation, remains poorly understood. Using the natural temperature gradient in a temperate mountain forest, this study investigated the differences in functional microbial groups and functional genes involved in soil carbon, nitrogen and phosphorus cycling along the elevation gradient, and analyzed the associations between environmental factors and these differences. The results showed that the low-elevation gradient (LE) had significantly higher abundances of genes involved in carbon degradation (pfkC, pgi1, and LSC1) but significantly lower abundances of those involved in carbon fixation (K18602, K18603, and K18604). Compared with the high-elevation gradient (HE), the LE had a significantly higher abundance of the nitrogen-cycle gene involved in organic degradation and synthesis (nao), but significantly lower abundances of denitrification (norB) and dissimilatory nitrate reduction genes (narG, narI, and napC). The abundances of the key genes involved in phosphorus metabolism (aphA and purO) were significantly higher at HE than at LE, whereas the abundance of the key gene associated with phosphorus transport (phnT) was significantly lower. The composition of the microbial community at the phylum level involved in carbon, nitrogen and phosphorus cycling at different elevations was similar, but the relative abundance of Thermoproteota and Nitrospirota increased significantly at HE. The annual average temperature, pH and carbon acquisition enzymes (β-glucosidase and β-D-cellobiosidase) were significantly associated with microbial community composition and functional genes related to carbon, nitrogen and phosphorus cycles. Additionally, genes involved in the carbon, nitrogen and phosphorus cycles were closely related through synergy and antagonism, especially the metabolic pathways encoded by purO, phnT and nrfA. These results provide metagenomic insights into the response patterns of microbial functional potential associated with soil carbon, nitrogen, and phosphorus cycling along an elevational gradient in a warm-temperate forest. Full article

Salinity is a key driver of microbial community structure and function in salt lake ecosystems, yet how it shapes functional genes involved in carbon (C), nitrogen (N), and phosphorus (P) cycling remains poorly understood. We collected metagenomic samples along a natural salinity gradient in Yuncheng Salt Lake and examined how salinity was associated with microbial taxonomic and functional diversity and with C, N, and P cycling genes. Both diversity metrics decreased significantly with increasing salinity and were positively correlated with each other. The composition and abundance of C, N, and P cycling genes differed significantly among the low-, medium-, and high-salinity groups. In carbon cycling, most carbon fixation genes were more abundant at higher salinity, whereas most carbon degradation genes were less abundant; within carbon fixation, reductive tricarboxylic acid (rTCA) cycle and Calvin cycle gene abundances were higher. In nitrogen cycling, nitrogen mineralization and assimilation genes were significantly more abundant. In phosphorus cycling, transporter and pyrimidine metabolism genes were more abundant, whereas the relative contribution of purine metabolism genes declined. Co-occurrence network analysis revealed dense positive co-occurrence associations among C, N, and P cycling genes, with mer, GLU, and ppk1 as highly connected genes. Mantel tests identified salinity and pH as the primary environmental factors associated with functional gene variation. These results suggest that salinity may regulate C, N, and P cycling genes partly by reshaping microbial community structure in salt lake ecosystems. Full article

The present study experimentally investigates the influence of n-octanol addition to Jet-A fuel on the combustion performance and emission behavior of a micro-turboprop-based hybrid UAV (“Unmanned Aerial Vehicle”) power system. The experiments were conducted on a dedicated hybrid propulsion test bench equipped with a KingTech micro-turboprop engine mechanically coupled to a T-Motor electric generator and supplying a regulated 48 V DC bus. The system is capable of delivering approximately 3 kW of continuous electrical power, with peak values reaching 3.5 kW. Jet-A and three n-octanol/Jet-A blends containing 10%, 20%, and 30% n-octanol by volume, denoted O10, O20, and O30, respectively, were tested under four operating regimes ranging from idle to 2500 W electrical load. Exhaust gas temperature, carbon monoxide, sulfur dioxide, nitrogen oxides, electrical output, and near-field pollutant dispersion were evaluated. The results show that n-octanol addition affects engine behavior in a strongly load-dependent manner. At idle, the O10 blend reduced CO concentration from approximately 2520 ppm for Jet-A to approximately 2270 ppm, corresponding to a reduction of about 9.9%. At the same operating condition, O10 reduced exhaust gas temperature from approximately 498.3 °C to 463.2 °C, while O20 and O30 produced stronger cooling effects. At intermediate regimes, the oxygenated molecular structure of n-octanol contributed to lower CO formation in selected cases, indicating improved combustion-completeness behavior. At high load, however, exhaust gas temperatures converged toward or exceeded those of Jet-A, particularly for O30, showing that higher octanol fractions may introduce additional thermal constraints. Among the tested fuels, O10, corresponding to 10% n-octanol by volume, provided the most balanced behavior across the investigated operating range, from idle to 2500 W electrical load. The dispersion measurements performed at 30 m from the source further showed that ambient pollutant concentrations are strongly influenced by wind speed, wind direction, and plume transport. These findings support moderate n-octanol blending as a promising transitional strategy for small-scale hybrid UAV propulsion systems, while highlighting the need for future repeated testing, direct fuel-flow measurement, and numerical dispersion modeling. Full article

Peanut (Arachis hypogaea L.) yield depends on biological nitrogen fixation, but the molecular mechanisms underlying the combined effects of arbuscular mycorrhizal fungi (AMF) and calcium fertilizer on nodulation remain unclear. Here, we used integrated transcriptomic and metabolomic analyses to investigate potential mechanisms in peanut roots. Compared with the non-inoculated control, AMF inoculation alone was associated with a 22.1% higher nodule number per plant. The combined application of AMF and CaO showed a 35.9% higher nodulation than AMF alone, and a 30.9% higher AMF colonization rate than AMF alone was also observed. Mechanistically, AMF colonization was associated with enhanced carbon-nitrogen metabolic profiles and up-regulation of phenylpropanoid metabolism-related pathways, suggesting a potential role in providing energy, carbon skeletons, and signaling molecules for nodule formation. Calcium fertilizer correlated with strengthening of the glyoxylate cycle and pentose phosphate pathway, possibly contributing to the energy supply for nodulation. It also affected genes related to protein secretion and lipid metabolism, with observed changes in membrane lipids and transport metabolites, which may enhance symbiotic interface function. This study reveals the multi-level mechanisms through which AMF and calcium fertilizer collectively promote peanut nodulation, providing a systems-level perspective on plant–microbe–nutrient relationships during symbiosis. Our findings offer new insights for sustainable agriculture by reducing chemical nitrogen inputs and promoting nodulation in legumes. Full article

Long-term excessive nitrogen application in arid cotton fields increases nitrate leaching risk during fallow and disrupts rhizosphere microecology. To clarify the cross-growth-stage regulatory effects of the biostimulant γ-polyglutamic acid (γ-PGA) combined with chemical fertilizer on rhizosphere microbial communities, we compared chemical fertilizer alone (NK) and γ-PGA plus chemical fertilizer (GT) using rhizosphere soils collected at boll-setting (August) and fallow (October), with physicochemical measurements and metagenomic sequencing technology. At boll-setting, GT lowered pH by 0.74 units compared with NK and increased NH₄⁺-N, NO₃⁻-N, and TN by 339.3%, 491.4%, and 23.0%, respectively. By fallow, GT increased TOC by 70.6% and maintained NH₄⁺-N at 18.38 mg/kg, while NK accumulated 66.85 mg/kg NO₃⁻-N. GT buffered post-harvest fungal community disturbance (Shannon: GT 4.06 vs. NK 2.80) and shifted bacterial communities toward oligotrophic taxa and archaea toward ammonium-preferring taxa. A metagenomic LEfSe analysis showed that GT was enriched in functional genes related to [Q]: Secondary metabolite biosynthesis, transport and catabolism, [T]: Signal transduction mechanisms, and [V]: Defense mechanisms, indicating a shift from resource acquisition to conservative maintenance. Mantel tests revealed that microbial functional profiles showed the strongest association with NH₄⁺-N (r = 0.828 in August, r = 0.883 in October, p < 0.001). Thus, γ-PGA with chemical fertilizer stabilizes fallow rhizosphere microbial communities, reduces nutrient leaching, and promotes carbon–nitrogen co-retention. Full article

In urban green spaces, stand density and pruning jointly modulate canopy structure, plant resource allocation, and leaf physiological traits. However, their interactive effects on the spatial heterogeneity of canopy photosynthetic characteristics remain poorly understood, which hinders the development of low-carbon, high-efficiency management strategies for urban forests. In this study, 50-year-old camphor tree (Cinnamomum camphora (L.) Presl) plantations with three density gradients were investigated to disentangle the interactive effects between stand density and pruning. The results showed that stand density dominated the resource competition regime within the canopy. In low-density stands, mean canopy leaf carbon (C), nitrogen (N), chlorophyll concentration (Chl), maximum net photosynthetic rate (A_max), stomatal conductance (g_sw), mesophyll conductance (g_m), actual photochemical efficiency of PSII (Φ_PSII), maximum Rubisco carboxylation rate (V_cmax), and maximum electron transport rate for RuBP regeneration (J_max), were significantly higher than those in medium- and high-density stands. Most photosynthetic traits increased logarithmically with increasing light intensity in low-density stand, whereas they followed parabolic trends in medium- and high-density stands with depressed values observed in upper sunlit leaves. Pruning triggered a physiological compensatory response in remaining leaves, significantly enhancing canopy C, N, Chl, and photosynthetic parameters such as A_max, g_sw, g_m, and Φ_PSII. Notably, the increments in canopy-averaged N, Chl, Φ_PSII and V_cmax/J_max following pruning were substantially greater in low-density stand than in medium- and high-density stands. Pruning predominantly regulated the spatial distribution of canopy photosynthesis. As stand density increased, pruning compensated for the insufficient photosynthetic capacity in the lower canopy, and decreased photosynthetic heterogeneity across canopy positions, but it failed to achieve targeted enhancements of whole-canopy photosynthetic potential. Concurrently, increasing stand density gradually shifted photosynthetic limitation from mesophyll to stomatal, and pruning further exacerbated stomatal limitation in the upper sunlit leaves of high-density stand. Consequently, high stand density weakened the responsiveness of photosynthetic traits to N. In addition, pruning significantly reduced nitrogen use efficiencies for A_max, g_sw, g_m, and J_max, due to N redundancy in the low-density stand. This study advances the mechanistic understanding of how urban forest management optimizes within-canopy photosynthetic resource allocation, and provides scientific support for enhancing the carbon sink function of urban green spaces. Full article

Water contamination with surface-active agents, such as sodium lauryl sulfate (SLS), represents a serious environmental concern, driving the need for efficient and low-cost alternative adsorbents as a step toward sustainable waste valorization. In this study, waste biomass derived from plum stones, date stones, and walnut shells was successfully transformed into activated carbons via chemical activation using potassium hydroxide (KOH) at 850 °C with a 1:1 impregnation ratio. The synthesized materials underwent comprehensive physicochemical characterization utilizing TG-DSC, elemental analysis, Boehm titration, SEM, TEM, and nitrogen physisorption (BET), whereas their adsorption performance was evaluated against aqueous SLS solutions across various concentrations. The obtained results reveal a predominantly microporous structure with a high specific surface area, reaching up to 1059.01 m²/g for ACdate. The equilibrium adsorption data were well described by the Langmuir isotherm model, which yielded model-estimated asymptotic adsorption capacities (q_m) of 219.70 mg/g for ACwalnut, 178.25 mg/g for ACdate, and 57.80 mg/g for ACplum. These values represent Langmuir-derived model parameters rather than experimentally attained adsorption capacities within the investigated concentration range. Notably, despite having a lower specific surface area than ACdate, ACwalnut exhibited the highest Langmuir-estimated q_m, which may be associated with its structural balance and well-developed mesoporous network (0.210 cm³/g), facilitating the intraparticle transport of SLS molecules. These findings highlight that high efficiency originates from a synergistic combination of accessible porosity, a mesoporous transport network, hydrophobic character, and specific surface functional groups, demonstrating the exceptional potential of these activated carbons for anionic surfactant wastewater remediation. Full article

Lithium-oxygen (Li-O₂) batteries are a compelling next-generation energy storage candidate owing to their ultrahigh theoretical specific energy, but their practical deployment is critically limited by sluggish cathodic oxygen reduction/evolution kinetics, severe polarization, and poor cyclability. Here, we design a composite catalyst consisting of ultrasmall iron clusters uniformly anchored on a three-dimensional nitrogen-doped carbon aerogel (Fe@NC). The material is synthesized via bidirectional freeze-drying followed by high-temperature reduction carbonization using chitosan, cellulose nanocrystals, and zinc acetate; sublimation of zinc during pyrolysis effectively suppresses iron aggregation, yielding highly dispersed Fe0 clusters of ~10 nm while preserving the aerogel’s hierarchical porous architecture rich in pyridinic and pyrrolic N species. Electrochemical tests show that Fe@NC delivers a deep-discharge specific capacity of 18,000 mAh/g, substantially outperforming pristine carbon aerogel and commercial Ketjen black, and maintains stable cycling over 280 cycles at 500 mAh/g. Microscopic and spectroscopic analyses confirm that Fe@NC promotes uniform, fine-particle Li₂O₂ deposition without pore blockage and enables its complete reversible decomposition upon charging, effectively mitigating electrode passivation. This work demonstrates that the synergistic combination of carbon aerogel mass-transport benefits and iron cluster catalytic activity provides a viable, scalable route to high-performance Li-O₂ battery cathodes. Full article

Phenolic resin pyrolytic carbon is a key matrix phase in carbon-based refractories and carbon/carbon composites; however, its defect-rich glassy carbon structure exhibits poor oxidation resistance at elevated temperatures. In this work, we report a facile one-step thermal-treatment strategy using melamine as a nitrogen source to prepare nitrogen-modified phenolic resin pyrolytic carbon (NC). The structural evolution and oxidation behavior of samples carbonized at 500–800 °C were systematically investigated by XRD, SEM, TEM, FT-IR, Raman, XPS, BET, and TG-DSC. The results reveal that melamine-derived nitrogen exists in two distinct forms: at 500–700 °C, a carbon nitride-rich phase consistent with graphitic carbon nitride (g-C₃N₄) forms sheet- and belt-like structures on the carbon surface and partially fills the internal pores; at 800 °C, its long-range crystalline signature disappears, while pyridinic, pyrrolic, and graphitic nitrogen remain in the carbon framework. From 500 to 800 °C, the relative N 1s fraction of pyridinic N decreases from 72.33% to 44.38%, whereas graphitic N increases from 0.47% to 24.09%. Meanwhile, the pore structure evolves from a mesopore-dominated architecture with a limited accessible surface area at 500–600 °C to a micropore-rich structure at 700–800 °C. Relative to unmodified PR-800, NC-800 exhibits an approximately 30 °C higher onset oxidation temperature and an approximately 40 °C higher complete oxidation temperature, together with a lower maximum mass-loss rate and a delayed, broadened exothermic response. These results show that melamine-derived pore regulation and skeletal nitrogen doping jointly retard oxygen transport and suppress oxidation-active defect sites, providing a simple and potentially scalable route for improving the high-temperature oxidation resistance of phenolic resin pyrolytic carbon. Full article

Trehalose-6-phosphate (T6P) is a key signalling metabolite that integrates carbon availability with development and stress responses in plants. T6P levels are controlled by trehalose phosphate synthase (TPS) and trehalose-6-phosphate phosphatase (TPP) enzymes; however, while TPS enzymes have been studied extensively, the physiological functions of individual TPPs remain incompletely understood. Here, we investigated the role of TPPI in Arabidopsis using loss-of-function tppi mutants, a complemented line (tppi+35S::TPPI), and TPPI-overexpressing (TPPI-OEX) plants. The tppi mutant exhibited delayed flowering accompanied by reduced expression of CO, FT, and SPL3, while complementation restored wild-type (WT) flowering time. TPPI-OEX plants displayed an intermediate flowering phenotype with moderate reductions in CO and FT expression. Under nitrogen starvation, tppi plants showed enhanced anthocyanin accumulation, altered nitrate reductase regulation, characterised by lower total enzyme activity but a higher activation state, and enhanced expression of nitrate assimilation and uptake genes (NIA1, NIA2, NRT1.1, and NRT2.1). TPPI deficiency also altered photosynthetic performance, with enhanced photosystem I (PSI) acceptor-side limitation, increased non-photochemical quenching (NPQ), and a tendency toward reduced photosystem II (PSII) electron transport, indicating altered photosynthetic electron transport and energy dissipation. Taken together, these results indicate that TPPI contributes to the regulation of flowering time, nitrogen responses, and photosynthetic performance, suggesting broader effects of TPPI on plant developmental and physiological processes. Full article

Per- and polyfluoroalkyl substances (PFASs) are persistent, surface-active contaminants for which soil represents the largest terrestrial reservoir. This review synthesizes a rapidly expanding but fragmented body of literature in order to reframe PFAS not merely as a groundwater transport problem but as a systemic stressor of soil health, drawing together their reported effects on the chemical, physical and biological properties of soils and giving particular attention to the calcareous, alkaline, carbon-poor and seasonally dry soils of the Mediterranean. The reviewed evidence suggests that, chemically, PFASs perturb the coupled carbon and nitrogen cycles rather than the bulk soil reaction, transiently stimulating and then depressing organic carbon turnover, drawing down the dissolved organic carbon pool and disturbing nitrification, while their retention and bioavailability are governed chiefly by organic carbon, chain length and pH. Physically, the surfactant character that defines these molecules lowers the surface tension of soil water and concentrates PFASs at the air–water interface, so that in unsaturated and drought-prone soils much of the burden is retained and then released episodically, most clearly on rewetting after dry periods. Biologically, the literature consistently reports dose-dependent declines in microbial viability, diversity and enzyme activity, alongside toxicity to earthworms and other soil fauna, with sensitivity strongly modulated by soil texture and organic matter. Across all three domains, the Mediterranean emerges as both potentially vulnerable and conspicuously understudied, the available data being clustered in a few western countries and effectively absent for much of the eastern and southern basin, so that the regional assessment offered here rests largely on mechanistic inference rather than on direct observation. The review argues that these coupled mechanistic and geographic gaps define an urgent, region-specific research agenda for the protection of soil health. Full article

This study evaluated the synergistic effects of sodium chloride (NaCl) and cytidine monophosphate (CMP) on enhancing the co-production of astaxanthin and fatty acids while suppressing secondary cell wall (SCW) formation in Haematococcus lacustris (synonym: H. pluvialis) under high-light stress. An orthogonal design identified the optimal combination (0.5 g/L NaCl and 0.5 mM CMP), which significantly increased astaxanthin yield by over 35.6% and total fatty acid yield by 28%, while maintaining 96.8% of cells in motile state (SCW-deficient). Physiological analyses revealed elevated reactive oxygen species levels, concomitant with higher actual photochemical efficiency (Fv′/Fm′) and relative electron transport rates II (rETR(II)) along with enhanced non-photochemical quenching (NPQ) capacity, and metabolic reprogramming characterized by the accumulation of lipids, sugars, and starch alongside decreased protein yield. Metabolomics indicated reduced carbon supply for SCW polysaccharide biosynthesis, coupled with decreased protein yield and altered amino acid profiles characteristic of nitrogen-limited metabolism, which collectively favored the reallocation of carbon resources toward nitrogen-free high-value products. Transcriptomics confirmed the downregulation of SCW component biosynthetic genes and the upregulation of the methylerythritol phosphate (MEP) pathway and astaxanthin biosynthetic pathway. Scale-up experiments validated this strategy for producing astaxanthin-rich motile cells, offering a promising approach for microalgal biorefinery. Full article

Given that large-scale storage and transportation of liquid hydrogen are key to realizing the hydrogen economy, tank containers have attracted much attention for their flexibility. To minimize evaporation losses, efficient support structures are essential for these liquid hydrogen tank containers. Herein, a carbon fiber-reinforced polymer (CFRP) suspension ring is developed to support the inner vessel of liquid hydrogen tank containers. By using a special resin matrix and optimizing its curing process, the suspension ring capitalizes on a small cross-sectional area and low thermal conductivity, thereby significantly mitigating the cold-bridge heat transferred from the outer vessel to the inner vessel. Experimental results demonstrate that the tensile strength, outgassing rate, and fatigue performance of the suspension ring at both 77 K (liquid nitrogen temperature) and 4 K (liquid helium temperature) can meet the design targets. Notably, its equivalent thermal conductivity was approximately 88% lower than that of a stainless steel structure of the same size. With the integration of this suspension ring into a 40 ft liquid hydrogen tank container, the daily liquid nitrogen evaporation rate was recorded below 0.082%/d. Furthermore, the holding time before the pressure reached 0.14 MPa exceeded 192 h with a 90% liquid hydrogen filling ratio. This work provides key technical support for high thermal insulation, long-endurance liquid hydrogen storage and transportation equipment. Full article

High-purity SiC powder is an important feedstock for SiC crystal growth, but thermal-field regulation becomes difficult during large-batch synthesis. This study examined an α-SiC powder-synthesis furnace with upper and lower induction-coil groups through numerical simulations and 70 kg synthesis experiments. A representative two-dimensional axisymmetric model was used to compare eight cases with different coil-turn or numerical power allocations. Redistributing the coil turns changed $E_1$, $E_2$, volumetric Joule heat density, $Q$, and the resulting temperature and calculated gas-phase velocity-magnitude fields. From C01 to C04, the maximum calculated temperature decreased from 2501.10 to 2359.13 K, while $\Delta T$ decreased from 242.57 to 76.20 K. Increasing the upper-coil numerical power raised the temperature level while reducing $\Delta T$ to 152.41 K. Increasing the lower-coil numerical power also raised the temperature level, but increased $\Delta T$ to 292.26 K. Equal-total-power comparisons showed that axial power allocation affected $T_{\mathrm{m}\mathrm{a}\mathrm{x}}$ and $\Delta T$. XRD identified 6H-SiC as the detected crystalline phase in both analyzed middle-region specimens, although X-ray-amorphous carbon could not be excluded. The specimens also differed in macroscopic appearance, measured impurity concentrations, and local nitrogen concentration profiles. Because the experimental conditions were maintained nominally unchanged except for the upper-coil current, these specimen-level differences may be associated with altered internal thermal conditions. Such changes may affect local equilibrium, supersaturation, and species transport, providing a possible link to the observed material differences. The numerical results identify coil-turn allocation and axial power allocation as variables for regulating the calculated furnace fields. Full article

Anthropogenic greenhouse gases (GHGs) and emissions from maritime transport represent a significant challenge for atmospheric monitoring and control. The Istanbul Strait, characterized by its narrow, winding geography and high traffic density, presents a unique chokepoint where these emissions directly impact local air quality. This study proposes a gas-focused integrated framework that combines Sentinel-5 Precursor (Sentinel-5P) TROPOspheric Monitoring Instrument (TROPOMI) satellite observations with Automatic Identification System (AIS) data to analyze atmospheric trace pollutant time series in the Istanbul Strait during 2025. A bottom-up emission methodology based on the IMO 4th GHG Study was employed, yielding annual gaseous pollutant totals of 213,678 tons of carbon dioxide (CO₂), 5970 tons of nitrogen oxides (NO_x), and 686 tons of sulfur oxides (SO_x). Time-series and cross-correlation analyses demonstrated a quantifiable relationship between AIS-derived NO_x estimates and TROPOMI NO₂ tropospheric column densities (r = 0.76, p < 0.05, n = 12), validating the use of satellite sensors for marine atmospheric monitoring. A decision support system (DSS) proof of concept (PoC) was developed to evaluate emission control scenarios through speed optimization. The results indicate that implementing a 10% speed reduction strategy could reduce CO₂ emissions by 18% (38,462 tons) and generate net economic savings of EUR 3.07 million under the European Union Emissions Trading System (EU ETS) carbon pricing framework. Furthermore, a scenario with a 20% speed reduction resulted in a 35% decrease in CO₂ emissions. The findings underscore the potential of integrating satellite-based gas remote sensing with AIS data, thereby facilitating real-time atmospheric monitoring and strengthening emission control policy enforcement in maritime chokepoints. Full article