Search Results (114)

Soil salinization is one of the most severe forms of land degradation in arid and semi-arid regions, posing substantial threats to agroecosystem stability and food security. In this study, saline–alkali soil collected from the Wuding River Basin in Yulin, Shaanxi Province was used to construct a three-factor amendment system comprising superabsorbent polymers (SAP), biochar, and humic acid. A systematic assessment was conducted to elucidate their combined effects on soil water–salt transport and crop growth. Results from one-dimensional constant-head infiltration experiments using indoor soil columns demonstrated that the application of amendments significantly increased cumulative infiltration and improved the uniformity of wetting-front advancement. Specifically, the treatments regulated the redistribution of salts within the soil profile; while surface salinity reduction varied, the leaching efficiency was significantly enhanced in the A2B2C2 treatment. Soil bulk density (BD) showed dynamic fluctuations during the growth cycle, peaking at 1.628 cm⁻³ during the branching stage, while high-rate biochar (A3) reduced BD by up to 13.64% compared to the control by the initial flowering stage. Fitting results based on the Philip and Kostiakov models further indicated that the combined amendment strategy—particularly the A2B2C2 treatment (30 kg/ha SAP, 15,000 kg/ha biochar, and 600 kg/ha humic acid)—markedly enhanced both the initial infiltration rate and the steady infiltration capacity. Field experiments corroborated the indoor findings: plant height and dry biomass of Melilotus officinalis (L.)Lam. were significantly higher under amendment treatments than in the control, driven by improved water availability, mitigated salt stress, and enhanced soil structure. Single-factor and multi-factor interaction analyses revealed that SAP exerted pronounced effects during early growth stages, whereas biochar and humic acid contributed more substantially during the middle to late stages through sustained regulatory functions. Collectively, the results demonstrate that the combined application of SAP, biochar, and humic acid improves the water–salt regime of saline–alkali soils through a coupled “water–salt–structure–plant” mechanism, ultimately enhancing crop productivity. This study provides both theoretical insights and practical guidance for the amelioration of saline–alkali soils. Full article

The design of implant surfaces that support bone integration while limiting bacterial colonization remains a central challenge in biomaterials science and engineering. In this work, zinc-doped biomimetic calcium phosphate (CaP-Zn) coatings were fabricated on Ti6Al4V through surface activation followed by deposition in supersaturated simulated body fluid (SBF). Acid and alkali–calcium treatments produced a porous, calcium-rich interface that enabled the uniform formation of apatite-like CaP layers. Zinc incorporation was achieved without suppressing the formation of CaP phases and led to systematic changes in coating microstructure and surface chemistry. Spectroscopic and structural analyses indicated Zn incorporation within the CaP matrix, consistent with partial Ca²⁺ substitution and its association with poorly crystalline domains. These features promoted controlled ionic release and localized dissolution–reprecipitation behavior. Antibacterial testing against Streptococcus mutans revealed a clear Zn-dependent reduction in bacterial viability, while cytocompatibility remained within acceptable limits at moderate Zn levels. Finally, the coatings combine intrinsic bioactivity with ion-mediated antibacterial functionality, offering a multifunctional surface strategy for advanced titanium-based implants. Full article

To address the bottleneck of poor biological nitrogen removal efficiency caused by the extremely low carbon-to-nitrogen (C/N) ratio of domestic sewage in alpine plateau regions, this study used Hordeum vulgare var. coeleste L., a characteristic crop endemic to the Qinghai–Tibet Plateau, as raw material and adopted pretreated highland barley straw as an external carbon source. Three parallel experiments were carried out using the anaerobic–aerobic–anoxic sequencing batch reactor (AOA-SBR) process to investigate the nitrogen removal performance and functional succession of the microbial community in the AOA-SBR system under three C/N ratio ranges: 5~7, 7~9, and 9~11. The results showed that the addition of an external carbon source significantly improved nitrogen removal efficiency. The optimal C/N ratio range for nitrogen removal in this study was determined to be 7~9. A weakly alkaline environment was conducive to denitrification. The fermentation broth prepared by alkali pretreatment contained a large amount of readily biodegradable organic matter with low toxicity, and achieved excellent nitrogen removal performance, helping to realize cost reduction and efficiency improvement in wastewater treatment. At the optimal C/N ratio of 7~9, the average removal efficiencies of ammonia nitrogen (NH₄⁺-N) and total nitrogen (TN) reached 94.46% and 61.32%, respectively, which were significantly improved compared with the blank control group without external carbon addition. During the experimental period, no obvious changes were observed in microbial abundance at the phylum level, whereas the community structure at the genus level responded significantly to the addition of a straw carbon source. Among them, genera with specific degradation capabilities for straw hydrolysates, such as norank_f__Chitinophagaceae and unclassified_f__Comamonadaceae, were highly sensitive to variations in the C/N ratio. These genera could partially replace the nitrification and denitrification functions of other microorganisms and played a key role in the nitrogen removal process. In contrast, Thauera, a typical conventional heterotrophic denitrifier, showed no significant response to changes in the C/N ratio, indicating that the straw-based external carbon source mainly affected microbial genera with specific hydrolysate-degrading functions. Full article

Continuous maize cropping is often associated with yield decline and soil degradation, yet the temporal responses of rhizosphere bacterial communities to prolonged monocropping remain incompletely understood. Here, we used a continuous maize cropping chronosequence representing 0, 1, 2, 3, 6, 7, and 8 years of cropping to evaluate soil physicochemical properties, maize yield, rhizosphere bacterial community composition, and BugBase-predicted phenotypes using 16S rRNA gene amplicon sequencing. Available potassium declined progressively with cropping duration, whereas alkali-hydrolyzable nitrogen (AN) increased and available phosphorus (AP) changed nonlinearly. Soil pH declined in the later stages of the chronosequence. Maize yield declined progressively with prolonged cropping, with reduction of 46–55% in the 6–8 years treatments relative to earlier within-plot peaks. Bacterial alpha diversity changed nonlinearly, with Shannon diversity peaking at C3, declining at C6, and partially recovering at C7–C8. Because years 4 and 5 were not sampled, the exact shape of the transition between C3 and C6 remains unknown. Community composition also shifted with cropping duration, including a relative decline in Proteobacteria and enrichment of Actinobacteria in the longer-duration treatments. At the genus level, Arthrobacter increased in the later stages of the chronosequence. Redundancy analysis indicated broad associations between community composition and soil variables, although the phylum-level model was only marginally significant. BugBase-predicted phenotypes also varied across treatments, but these functional inferences should be interpreted cautiously because they were derived from 16S-based predictions. Overall, our findings support nonlinear changes in rhizosphere bacterial communities along the continuous maize cropping chronosequence and suggest an unresolved transition between C3 and C6, followed by partial stabilization at later stages. However, due to the missing data for years 4–5 and the inherent limitations of the chronosequence design, the existence and timing of a proposed mid-term transition remain tentative. These findings highlight the need for complete annual sampling to resolve successional trajectories. Full article

Nitrous oxide (N₂O) emissions from agricultural soils are an important source of greenhouse gases and are strongly influenced by fertilization practices. In this study, a field experiment was conducted from 24 June to 12 October 2024, at a saline-alkali farmland site in Binzhou, Shandong Province, China, to evaluate the effect of Bacillus subtilis biofertilizer on N₂O emissions and to explore the underlying mechanisms. Compared with conventional chemical fertilization, the Bacillus subtilis biofertilizer treatment reduced the cumulative N₂O emission flux by 39%. At the N₂O emission peak, the emission flux under the biofertilizer treatment was 40.7%, 18.2% lower than that under the CF and CBF treatments, respectively. Functional gene analysis further showed that at the N₂O emission peak, the biofertilizer treatment reduced the copy number of Bacterial-amoA by 94% and 83% relative to CF and CBF, respectively, while the hao gene abundance in the CF treatment was 7.67, 24 times higher than that in the BF and CBF treatments, indicating that the reduction in N₂O emissions was closely associated with suppression of the nitrification process. In addition, the biofertilizer treatment showed the highest plant nitrogen uptake. All fertilization treatments significantly increased crop yield compared with the control, whereas there was no significant difference in yield among BF, CF, and CBF treatments (p > 0.05). These findings indicate that B. subtilis biofertilizer can mitigate N₂O emissions from saline-alkali farmland without reducing crop yield and may represent a promising strategy for sustainable agricultural management. Full article

To reduce staining, paper conservators have increasingly treated artworks on paper with enhanced washing using chelating agents, which form complexes with metallic ions, thus facilitating the removal of stains. However, questions remain regarding the efficacy of the method and its impact on the long-term preservation of paper. A treatment of enhanced washing was undertaken on a nineteenth-century mezzotint printed using the chine collé technique, by David Lucas after a painting by John Constable, which was disfigured by significant foxing stains. This intervention provided the opportunity to investigate the mechanism and efficacy of the treatment and whether an alkali reserve could successfully be reintroduced. The print was analysed before, during, and after treatment with a Bruker M6 Jetstream scanning X-ray fluorescence (XRF) spectrometer. The results provided spatially resolved information on the effects of the treatment and gave new insights into the heavily debated causes of foxing on paper, challenging the link with iron contamination. Instead, the distribution of foxing stains showed a correlation with the presence of potassium and calcium, and their reduction during washing corresponded with an improvement in appearance. Calcium replenishment proved only partially successful. Finally, scanning XRF has rarely been used for the analysis of artworks on paper; this study proves its value for research. Full article

The increasing demand for sustainable and environmentally friendly construction materials has spurred interest in biopolymer composites reinforced with agricultural waste. Rice husk (RH), a byproduct of rice milling, is abundant and rich in lignocellulosic fibers and silica, making it excellent for use in fiber-reinforced biopolymers. The novelty of this study lies in its integrated and construction-oriented evaluation of rice husk (RH)-reinforced biopolymers, combining mechanical, thermal, environmental, and economic perspectives within a single framework. The study introduces a novel comparative approach by benchmarking multiple polymer matrices-including PP, recycled HDPE, epoxy, PLA, and bio-binders-under unified quantitative performance criteria. Another key novelty is the identification of the dual functional role of silica-rich RH in simultaneously enhancing structural strength and flame retardancy while contributing to carbon emission reduction. With a high silica content (15–20%) and lignocellulosic structure, RH serves as a natural filler that enhances the performance of polymer matrices such as polypropylene (PP), epoxy, polylactic acid (PLA), and recycled polyethylene. Mechanically, RH-reinforced composites demonstrate significant improvements in tensile, flexural, and impact strength. For example, PP composites with NaOH-treated RH and coffee husks achieved tensile strengths between 27.4 MPa and 37.4 MPa, with corresponding Young’s modulus values ranging from 1656 MPa to 2247.8 MPa. Recycled HDPE-RH blends reached tensile strengths up to 74 MPa and flexural values of 39 MPa, validating their structural applicability. Epoxy matrices embedded with 0.45 wt.% RH nanofibers showed degradation thresholds of 411 °C and 678 °C, reflecting substantial thermal resistance. Flame retardancy is further improved by the presence of RH biochar, which leads to reduced peak heat release rate (PHRR) and enhanced char formation. In building insulation applications, RH-based composites exhibit low thermal conductivity values between 0.08 and 0.14 W/m·K, contributing to energy efficiency. Economically, RH reduces material costs by 30–40%, while environmentally, its integration lowers carbon emissions in PP composites by up to 10%, and promotes biodegradability. Despite challenges such as moisture absorption and interfacial adhesion, these can be mitigated through alkali treatment, compatibilizers (e.g., MAPP), or hybrid reinforcement strategies. Full article

Reducing emissions of nitrogen compounds represents a significant challenge in environmental protection, and catalytic treatment is an effective approach. Carbon-based catalysts offer a promising alternative by exploiting the redox properties of carbon materials and eliminating the need for external reducing agents. In this study, nitrogen-free and nitrogen-doped activated carbons were used for NO reduction. The catalysts were developed by incorporating transition metals (Cu and Fe), alkali metals (K), and bimetallic Cu-K formulations. The addition of K to Cu and the presence of nitrogen functionalities improved the catalytic performance and an optimum Cu/K ratio was identified. The best-performing catalyst, AC_M_BM@5Cu5K, achieved 100% NO conversion at 410 °C, producing mainly N₂ and CO₂, while N₂O was detected as an intermediate and CO was not observed. The catalyst’s stability was evaluated in a 100 h continuous test at 376 °C, during which the catalyst maintained approximately 90% NO conversion for 40 h before deactivation. The deactivation mechanism is discussed in detail. Full article

Biochar is widely used in composting to reduce nitrogen loss; however, the application of acid-modified and alkali-modified biochar in composting remains insufficient. We hypothesize that acid-modified maize straw biochar can simultaneously reduce NH₃ and N₂O losses during the composting process. To test this, a composting experiment was conducted with four treatments: a control with pig manure and corn straw only (CK), adding 5% corn straw biochar (BC), adding 5% HNO₃-modified corn straw biochar (BCN), and adding 5% NaOH-modified corn straw biochar (BCNa). The results showed that, compared to CK, NH₃ emissions were not decreased by BC, but significantly reduced (p < 0.05) by 32.6% in BCN and 36.8% in BCNa, respectively. N₂O was significantly decreased (p < 0.05) by 27.6% in BC and 30.9% in BCNa, respectively. However, BCN significantly increased N₂O emission (p < 0.05) by 368.7%, compared to CK. Compared to CK, the global warming potential (GWP) in the BCNa treatment was significantly reduced by 35.2% (p < 0.05), while the GWP in BCN was significantly decreased by 10.3%. Overall, although BCN treatment may increase N₂O emissions, it can still reduce the GWP. In comparison, BCNa treatment achieves the most significant reduction in GWP during pig manure composting. Full article

The valorization of dredged sediments represents a major environmental and logistical challenge, particularly in the context of forthcoming regulations restricting their marine disposal. This study investigates the potential of untreated dredged sediments as sustainable raw materials for geopolymer binder development, with the dual objective of sustainable sediment management and reduction in cement-related environmental impact. Dredged sediments from the Grand Port Maritime de Bordeaux (GPMB) were activated with sodium hydroxide (NaOH) and sodium silicate (Na₂SiO₃), both alone and in combination, with supplementary aluminosilicate and calcium-rich co-products, to assess their reactivity and effect on binder performance. A multi-scale experimental approach combining mechanical testing, calorimetry, porosity analysis, Scanning Electron Microscopy and Energy-Dispersive Spectroscopy (SEM–EDS), X-ray diffraction (XRD), Thermogravimetric Analysis (TGA), and solid-state Nuclear Magnetic Resonance (NMR) was employed to challenge the commonly assumed inert behavior of sediments within geopolymer matrices, to elucidate gel formation mechanisms, and to optimize binder formulation. The results show that untreated sediments actively participate in alkali activation, reaching compressive strengths of up to 5.16 MPa at 90 days without thermal pre-treatment. Calcium-poor systems exhibited progressive long-term strength development associated with the formation of homogeneous aluminosilicate gels and refined microporosity, whereas calcium-rich systems showed higher early age strength but more limited long-term performance, linked to heterogeneous gel coexistence and increased total porosity. These findings provide direct evidence of the intrinsic reactivity of untreated dredged sediments and highlight the critical role of gel chemistry and calcium content in controlling long-term performance. The proposed approach offers a viable pathway for low-impact, on-site sediment valorization in civil engineering applications. Full article

A two-year (2024–2025) field experiment was conducted in southern Xinjiang to alleviate soil compaction and severe salinization in saline–alkali soils and to evaluate the combined effects of tillage depth and subsurface drain spacing on soil improvement. Six treatments were established with three deep tillage depths, 70 cm (W1), 50 cm (W2), and 30 cm (W3), and two subsurface drain spacings, 20 m (S1) and 40 m (S2). Treatment effects on soil water–salt dynamics, soil physical properties and structure, ionic composition, and subsurface drainage and salt removal were analyzed. This study provides mechanistic and practical evidence that coupling deep tillage with subsurface drainage creates a more effective leaching–drainage pathway than either measure alone and enables robust optimization of design parameters (drain spacing × tillage depth) for saline–alkali land improvement in arid regions. Deep tillage in combination with subsurface drainage significantly increased soil profile water content, total porosity, and cumulative subsurface drainage and salt export, all of which reached their maxima under S1W1; it also significantly reduced bulk density, total salinity, and the concentrations of Na⁺, K⁺, Mg²⁺, Ca²⁺, Cl⁻, and SO₄²⁻, which reached their minima under S1W1. After two spring irrigation–leaching events (in 2024 and 2025), surface salt accumulation in the soil profile was markedly alleviated, and the mean salinity in the 0–20 cm layer decreased by 45.68% across treatments. The S1W1 treatment achieved the best desalinization performance in both leaching events, with reductions of 41.36% and 44.68%, respectively. Pearson correlation analysis indicated that the desalinization effect was significantly negatively correlated with porosity and significantly positively correlated with bulk density and ionic concentrations. Overall, coupling deep tillage with subsurface drainage effectively reduced soil salinity and harmful ions, improved soil structure, and enhanced drainage-mediated salt removal, with the 70 cm tillage depth combined with a 20 cm drain spacing delivering the best performance. Full article

Chemical and plant-based strategies have become increasingly critical for the remediation of saline–alkali soils. However, the underlying mechanisms driving improvements in soil quality and ecological functionality remain insufficiently understood. In this study, we adopted a synergistic remediation approach that integrated multiple switchgrass (Panicum virgatum L.) cultivars with a coal-based soil amendment to enhance saline–alkali land. A field experiment was conducted using five switchgrass varieties (YM-1, YM-2, YM-3, YM-4, and YM-5), each receiving a uniform application of the coal-based soil conditioner at 10 t ha⁻¹. A traditional control group was not included in this study, as the experimental design focused on direct comparisons between varieties. Our results showed that soil ionic composition played a significant role in shaping microbial activity. Notably, we found that YM-5 treatment exhibited the highest relative soil microbial abundance (22.1%) under the condition of soil amendments. Furthermore, the YM-5 treatment significantly reduced soil Na+ content and exchangeable sodium percentage (ESP) (p < 0.05), outperforming other treatments. Compared to YM-2, the YM-5 treatment also resulted in substantial increases in soil organic carbon (SOC) and available potassium (AK), increases of 78.28% and 54.3%, respectively. In addition to enhancing physicochemical parameters, the integration of switchgrass and amendment promoted soil biological vitality. For example, the YM-2 treatment achieved a 7.4% increase in catalase (CAT) activity and a 6.3% reduction in soil pH compared to YM-3, indicating improved redox balance and acid–base regulation. Collectively, these findings provide direct empirical evidence supporting the effectiveness of switchgrass–amendment combinations in saline–alkali soil restoration. Among the tested cultivars, YM-5 demonstrated superior ecological performance and is recommended as the most suitable genotype for saline–alkali soil amelioration when used in conjunction with coal-based amendments. Full article

Within the global epidemiological landscape, methicillin-resistant Staphylococcus aureus (MRSA) stands out as a major contributor to infectious disease burden. The persistent public health crisis it presents arises from a dual challenge: intrinsic multidrug resistance coupled with a high rate of healthcare-associated infections. Recent studies have shown that propolis has unique advantages in bacterial infection prevention and treatment. The present study revealed that propolis ethanolic extract (PEE) exhibited notable antibacterial activity against both MRSA ATCC 43300 and MRSA CI2, with a minimum inhibitory concentration (MIC) of 128 μg/mL for each strain. Crystal violet (CV) staining and XTT sodium reduction assays were employed to evaluate the anti-biofilm efficacy of PEE. CV staining revealed that PEE significantly inhibited biofilm formation and reduced the biomass of pre-formed biofilm. Additionally, the XTT sodium reduction assay demonstrated a substantial reduction in the metabolic activity of the biofilm-embedded. Scanning electron microscopy and bacterial adhesion experiments revealed that PEE significantly reduced bacterial adhesion and aggregation. Furthermore, experiments on the synthesis of extracellular polysaccharides and proteins showed that PEE inhibits the production of water-soluble and alkali-soluble polysaccharides and extracellular proteins. Real-time quantitative Polymerase Chain Reaction (RT-qPCR) analysis revealed that PEE inhibited the expression of icaADBC, fnbAB, clfAB, and sarA. These results revealed that PEE inhibits biofilm formation and development by inhibiting the expression of sarA, icaADBC, fnbAB, and clfAB, thereby reducing the synthesis of extracellular polysaccharides and proteins to attenuate the adhesion capacity of MRSA. In summary, this study provides experimental evidence for the development of PEE as a potential antimicrobial agent for the prevention and treatment of MRSA-associated infections. Future work will focus on identifying its key active monomers and investigating its therapeutic effects and mechanisms of action in animal models. Full article

The combination of controlled-release urea (CRU) and conventional urea (CU) has become an important practical strategy to simultaneously increase rice yield, economic benefits, and nitrogen (N) use efficiency (NUE) with one-time fertilization management. However, the method by which the combination of CRU and CU intervenes with rice yield, economic benefits, and NUE in saline–alkali paddy fields has not yet been established. Accordingly, a two-year field experiment was set up with a total of seven treatments (CK, no N application; CUF, conventional urea split applications; RCUF, CUF treatment with 20% N reduction; CRBF1, 50%CRU + 50%CU one-time base application; CRBF2, 70%CRU + 30%CU one-time base application; RCRBF1, CRBF1 treatment with 20% N reduction; RCRBF2, CRBF2 treatment with 20% N reduction). The results showed that the controlled-release blended fertilizer (CRBF) treatments significantly increased the yield, economic benefits, and NUE over the two years. The CRBF1 and CRBF2 treatments significantly increased the rice yield by 5.10–6.77% and 10.41–11.04%, N recovery efficiency by 13.30–17.40% and 21.69–26.75%, and N agronomic efficiency by 10.40–13.91% and 21.26–22.10% compared to the CUF treatment, respectively. The RCRBF1 and RCRBF2 treatments maintained rice yields and significantly increased NUE compared to the CUF treatment. The analysis of yield components indicated that the greater rice yields of the CRBF were mainly attributed to increased panicle numbers and spikelet numbers per m². Furthermore, the post-anthesis dry matter, N accumulation, flag SPAD values, flag photosynthetic rates, and soil ammonium nitrogen content were higher during the grain-filling stage of the CRBF treatments compared to the CUF treatments. Compared with the CUF treatment, the CRBF1 and CRBF2 treatments increased economic benefits by 8.74–11.16% and 17.14–17.41%. Therefore, the combination of CRU and CU can increase rice yield, economic benefits, and NUE in saline–alkali paddy fields. Moreover, it is recommended to apply CRU and CU at a ratio of 7:3 in a single basal application as a green and efficient alternative N management strategy for saline–alkali paddy fields. The results provide a scientific basis for N management strategies in saline–alkali paddy fields. Full article

The aim of this work was high-temperature synthesis of PtPdCoNiCu/C nanoparticles with high-entropy alloy (HEA) structure as catalysts for oxygen reduction reaction. The materials were synthesized using a highly dispersed PtPd/C support, which was impregnated with Cu, Ni, and Co precursors followed by their precipitation with an alkali. Subsequently, the material was subjected to thermal treatment in a tube furnace at 600 °C for 1 h in a stream of argon containing 5% hydrogen. In combination with HRTEM, element mapping and line scan, XRD, and XPS data, these results confirm the successful synthesis of five-component PtPdCoNiCu high-entropy alloy nanoparticles on the surface of the carbon support. The obtained materials are characterized by a high electrochemical surface area of up to 63 m²/g(PGM), as determined by hydrogen adsorption/desorption and CO-stripping, and a high specific oxygen reduction reaction (ORR) activity of approximately 269 A/g(PGM) at 0.9 V vs. RHE. The synthesized material demonstrated outstanding stability, as confirmed by an accelerated stress test of 10,000 cycles. After the test, the electrochemical surface area decreased by only 12%, while the catalytic activity for ORR even increased. The proposed synthetic strategy opens a new pathway for obtaining promising highly stable five-component HEA nanoparticles of various compositions for application in catalysts. Full article