Search Results (1,980)

Investigating aluminum nitride (AlN) clusters is essential for understanding the properties of bulk AlN materials. The incorporation of hydrogen into AlN clusters represents an effective strategy for structural modification and for tuning their physicochemical properties. In this work, we conducted density functional theory (DFT) calculations on the dynamically stable global-minimum (GM) structure of Al₆N₆H₈. Compared to the precursor Al₆N₆ cluster, the incorporation of eight hydrogen atoms achieves coordination saturation of all aluminum and nitrogen atoms, inducing a structural transformation from a hexagonal prism with D_3d symmetry to a cuboid structure with D_2h symmetry. The HOMO–LUMO gap of the Al₆N₆H₈ cluster is increased by 1.85 eV compared to that of Al₆N₆, indicating a remarkable enhancement in stability. Chemical bonding and natural bond orbital (NBO) charge analyses reveal that the Al–N, Al–H, and N–H bonds are predominantly covalent single bonds, with a degree of ionicity arising from electronegativity differences. The hydrogen atoms bonded to Al and N can be substituted with a series of other atoms or functional groups, thereby further tuning the structures and properties of the clusters. To facilitate future experimental characterization, the infrared spectrum of Al₆N₆H₈ was calculated, which shows an overall blue shift in the Al–N bond’s bending and stretching vibrations compared to those in the Al₆N₆ cluster. Full article

Integrating catalytic function with oxygen-carrying capability into bi-functional materials represents a promising strategy for reverse chemical looping pyrolysis (RCLPy), which utilizes a reduced metal oxide to improve the bio-oil quality through in situ hydrogen donation and deoxygenation. In this study, a systematic evaluation of two typical catalysts (CaO and ZSM-5) was conducted for the pyrolysis of microalgae Nannochloropsis sp. under RCLPy conditions. First, the effect of each catalyst on the pyrolysis behavior of microalgae was analyzed by Gaussian fitting of derivative thermogravimetric (DTG) curves. Second, gases evolved during thermogravimetric analysis (TGA) were monitored in real time using Fourier-transform infrared spectroscopy (FTIR) for detecting CO, CO₂, H₂O, and functional groups (e.g., C–C, C=C, C=O), and mass spectrometry (MS) for tracking nitrogen-containing compounds. Third, the composition of bio-oils produced under RCLPy conditions was examined by Gas Chromatography–Mass Spectrometer (GC–MS) analysis. The results demonstrate that the catalyst enhances the bio-oil quality by elevating the content of aromatics up to 41.9 area% and that of aliphatic hydrocarbons to 19.1 area%, respectively, while reducing the content of nitrogen-containing compounds to 3.8 area%. However, the elimination pathway of oxygen and nitrogen elements involves different mechanisms. These findings provide valuable guidance for the design of bifunctional oxygen carriers aimed at enhancing the quality of bio-oil derived from microalgae pyrolysis. Full article

The Zhundong coalfield in Xinjiang contains vast reserves and is a crucial source of thermal coal. However, the Zhundong coal has a high content of alkali and alkaline earth metals, which makes it prone to ash deposition and slagging in boilers, thereby limiting its large-scale utilization. Fluidized-bed preheating is an emerging clean combustion technology that can reduce the slagging and fouling risks associated with high-alkali coal by modifying its fuel properties. This study employs circulating fluidized-bed preheating technology to treat high-alkali coal, with a focus on investigating the effect of the preheated air equivalence ratio on fuel preheating modification. Through microscopic characterization of both the raw coal and preheated char, the release and transformation behaviors of elements and substances during the preheating process are revealed. The results demonstrate that fluidized preheating promotes alkali metal precipitation, and increasing the preheated air equivalence ratio (λ_Pr) enhances gas production and elemental release, with a volatile fraction mass conversion of up to 84.57%. As the λ_Pr value increased from 0.28 to 0.40, the average temperature in the preheater riser increased from 904 °C to 968 °C. Compared to the raw coal, the specific surface area of the preheated char was enhanced by a factor of 3.6 to 9.1 times, with a more developed pore structure and less graphitization, thus enhancing the surface reactivity of the preheated char. The increase in λ_Pr also facilitated the conversion from pyrrolic nitrogen to pyridinic nitrogen, thus improving combustion performance and facilitating subsequent nitrogen removal. These findings provide essential data support for advancing the understanding of preheating characteristics in high-alkali coal and for promoting the development of efficient and clean combustion technologies tailored for high-alkali coal. Full article

The expanding insect farming industry generates up to 67,000 tons of frass per year. Its potential use as fertilizer is promising, but has not yet been widely studied. This study aimed to characterize the chemical composition, organic matter structure, ecotoxicity, and phytotoxicity of frass from four insect species in order to evaluate its potential as a fertilizer. We compared four types of insect frass (IF) (Tenebrio molitor, Galleria mellonella, Hermetia illucens, and Acheta domesticus) to Eisenia fetida vermicompost (EFV). We used physicochemical analyses (pH, electrical conductivity (EC), macro-micronutrients and dissolved organic carbon (DOC), spectroscopy (solid-state ¹³C nuclear magnetic resonance (NMR), and Fourier-transform infrared spectroscopy (FTIR)) and thermogravimetry/differential scanning calorimetry (TGA/DSC: R₁, R₂, Tmax), together with phytotoxicity (germination index, %GI) and ecotoxicity (toxicity units, TU) bioassays. Composition was species-dependent: A. domesticus showed the highest levels of nitrogen (N), phosphorus (P), and potassium (K); the concentration of DOC was higher in insect frass (IF) than in EFV, with the highest concentration found in IF of T. molitor. ¹³C NMR/FTIR profiles distinguished between frass (carbohydrates/proteins and chitin signals) and EFV (humified, oxidized matrix). Thermal stability followed: G. mellonella (R₁ ≈ 0.88) ≥ A. domesticus (0.79) > H. illucens (0.73) > EFV (0.67) > T. molitor (0.50). In bioassays, T. molitor and A. domesticus exhibited phytotoxicity (%GI < 30), whereas G. mellonella and H. illucens did not. EFV exhibited the highest %GI. Dilution increased %GI in all materials, especially in T. molitor and A. domesticus, and reduced acute risk (TU). Frass is not a uniform input: its agronomic performance emerges from the interaction between EC (ionic stress), the availability of labile C (DOC, C/N and low-temperature exotherms), and structural stability (R₁/R₂ and aromaticity). In terms of formulation, IF can provide nutrients that mineralize rapidly, whereas EFV contributes stability. Controlling the inclusion and dilution of materials (e.g., limiting the amount of T. molitor in blends) and considering the mixing matrix helps to manage phytotoxicity and ecotoxicity, and realize the fertilizer value of the product. Full article

TiO₂ nanoparticles were synthesized by a simple sol–gel route followed by high-temperature calcination at 800 °C, aiming to obtain an anatase-dominant reference photocatalyst with enhanced structural stability after severe thermal treatment. Raman spectroscopy and X-ray diffraction confirmed that anatase is the major crystalline phase, with only a minor rutile contribution after calcination at 800 °C. Nitrogen adsorption–desorption measurements revealed a narrow mesoporous contribution arising from interparticle voids and a relatively high specific surface area (108 m² g⁻¹) despite the severe thermal treatment, while electron microscopy showed nanometric primary particles assembled into compact agglomerates. Surface hydroxyl groups were identified by Fourier-transform infrared spectroscopy, consistent with sol–gel-derived TiO₂ systems. Diffuse reflectance UV–Vis spectroscopy combined with Kubelka–Munk and Tauc analysis yielded an optical band gap of 3.12 eV, typical of anatase TiO₂. Methylene blue (MB) was used as a probe molecule to evaluate photocatalytic activity under ultraviolet and visible light irradiation. Under UV illumination, degradation kinetics were governed by band-gap excitation and reactive oxygen species generation, whereas a slower but reproducible reference behavior under visible light was predominantly associated with surface-related effects and dye sensitization rather than intrinsic visible-light absorption. Overall, the results establish this anatase-dominant TiO₂ as a reliable high-temperature reference photocatalyst, retaining measurable activity after calcination at 800 °C and exhibiting UV-driven behavior as the dominant contribution. Full article

Wildfires are increasingly frequent and intense due to climate change, resulting in degraded soils with diminished microbial activity, reduced water retention, and low nutrient availability. In many regions, previously restored areas face repeated burning events, which further exhaust soil fertility and limit the potential for natural regeneration. Traditional reforestation approaches such as seed scattering or planting seedlings often fail in these conditions due to extreme aridity, erosion, and lack of biological support. To address this multifaceted problem, this study proposes a living, biodegradable hydrogel that integrates an engineered soil-beneficial microorganism consortium, designed to deliver beneficial compounds and nutrients combined with endemic plant seeds into a single biopolymeric matrix. Acting simultaneously as a biofertilizer, soil conditioner, and reforestation aid, this 3-in-1 system provides a microenvironment that retains moisture, supports microbial diversity restoration, and facilitates plant germination even in nutrient-poor, arid soils. The concept is rooted in circular economy principles, utilizing polysaccharides from food industry by-products for biopolymer formation, thereby ensuring environmental compatibility and minimizing waste. The encapsulated microorganisms, a Bacillus subtilis strain and a Nostoc oryzae strain, are intended to enrich the soil with useful compounds. They are engineered based on synthetic biology principles to incorporate specific genetic modules. The B. subtilis strain is engineered to break down large polyphenolic compounds through laccase overexpression, thus increasing soil bioavailable organic matter. The cyanobacterium strain is modified to enhance its nitrogen-fixing capacity, supplying fixed nitrogen directly to the soil. After fulfilling its function, the matrix naturally decomposes, returning organic matter, while the incorporation of a quorum sensing-based kill-switch system is designed to prevent the environmental escape of the engineered microorganisms. This sustainable approach aims to transform post-wildfire landscapes into self-recovering ecosystems, offering a scalable and eco-friendly alternative to conventional restoration methods while advancing the integration of synthetic biology and environmental engineering for climate resilience. Full article

Liquid digestate, a by-product of excess sludge in wastewater treatment plants (WWTPs), contains high concentrations of organic matter and essential nutrients that could promote plant growth. However, it also contains a significant number of pathogenic and opportunistic pathogenic microorganisms, which present major challenges in terms of its safe application. A sample taken from WWTP “Kubratovo” was treated using plasma devices. The aim was to evaluate the effect of treatment by two types of plasma sources on the content of pathogenic bacteria as well as the chemical composition of the liquid digestate. The Surfaguide plasma source demonstrated a higher disinfection effectiveness (100% for E. coli, Clostridium sp.; over 99% for fecal and total coliforms; 98% for Salmonella sp.). The β-device effectively removed (100%) the following groups: E. coli and Clostridium sp. However, its effectiveness was significantly lower for the other groups. The obtained results show that plasma treatment induces the transformation of nitrogen and phosphorus compounds, resulting in increased nitrite and phosphate concentrations. The application of cold atmospheric plasma disinfection significantly improved the sanitary and compositional characteristics of the liquid digestate. The Surfaguide achieved significantly better results than the β-device, confirming its suitability for sustainable resource recovery and safe agricultural use. Full article

Surface nanocrystallization is a critical approach for improving mechanical and functional properties of materials. Beyond conventional mechanical routes, chemical loading presents a promising pathway for nanocrystallization via interstitial-driven phase transformation. However, the characteristics and mechanisms underlying chemical load-induced nanostructuring remain insufficiently elucidated. This work investigates the surface nanocrystallization of 17-4 PH martensitic stainless steel during low-temperature plasma nitriding at 350 °C. Microstructural characterization combining XRD, EPMA, and TEM revealed a nitrogen-saturated layer with a maximum hardness of 13.5 GPa. The modified layer consists of nanoscale domains formed via a diffusionless martensite-to-austenite transformation, as evidenced by broadened FCC peaks, dark-field images, and the absence of elemental partitioning in EDX maps. This process is driven by the cyclic accumulation of chemical and elastic-strain energy at the advancing nitrogen diffusion front, triggering a self-sustaining, periodic transformation. This study introduces a chemical-driven nanocrystallization mechanism for novel design of surface-nanostructured steels via controlled thermochemical processing. Full article

High culture medium costs economically constrain bacterial cellulose (BC) production. In parallel, agro-industrial wastes are plentiful but often underutilised sources of carbon and nitrogen substrates that could support microbial growth and metabolite production. This study aimed to bioconvert agro-industrial waste sustainably into BC using response surface methodology. A novel lactic acid bacterium, Levilactobacillus brevis DSS.01, isolated from nata de coco wastewater, was evaluated alongside Acetobacter tropicalis KBC and Komagataeibacter xylinus TISTR 086 for BC production using Australian agro-industrial wastes. Preliminary screening identified pear pomace and rice bran as optimal low-cost carbon and nitrogen sources, respectively. The response surface methodology employing Box–Behnken Design determined the optimal agro-industrial waste medium composition for L. brevis DSS.01 to produce BC at 1.56 ± 0.15 g/L. The optimised agro-industrial waste medium substituted 85% of standard Hestrin-Schramm medium components, suggesting a significant reduction in culture medium and production costs. Scanning electron microscopy revealed BC fibres from L. brevis DSS.01 maintained a uniform diameter. Fourier transform infrared spectroscopy and X-ray diffraction analyses indicated minimal structural deviation in BC produced from optimised agro-industrial waste medium versus standard medium. These findings demonstrate economic and sustainable BC production through valorisation of agro-industrial residues, establishing lactic acid bacteria as alternative BC producers with potential food-grade applications in circular economy frameworks. Full article

To address the challenge of low nitrogen removal efficiency, particularly the difficulty in meeting total nitrogen (TN) discharge standards during low-temperature seasons and intermittent emission modes in conventional aquaculture wastewater treatment, this study proposed the novel application of bioretention systems. Biochar and sponge iron were used as fillers to construct three bioretention systems: biochar-based (B-BS), sponge iron-based (SI-BS), and a composite system (SIB-BS), for evaluating their nitrogen removal performance for aquaculture wastewater treatment. Experimental results demonstrated that under intermittent flooding conditions at 8.0–13.0 °C and increasing TN loading (9.48 mg/L–31.13 mg/L), SIB-BS maintained stable TN removal (79.7–86.7%), outperforming B-BS and SI-BS (p < 0.05). Under continuous inflow (influent TN = 8.4 ± 0.5 mg/L) at 8.0–13.0 °C, SIB-BS achieved significantly lower effluent TN (2.57 ± 1.5 mg/L) than B-BS (5.6 ± 1.6 mg/L) and SI-BS (5.0 ± 1.5 mg/L) (p < 0.05). Meanwhile, when the temperature ranged from 8.0 to 26.3 °C, SIB-BS exhibited a more stable and efficient denitrification ability. Mechanistic investigations revealed that coupling biochar with sponge iron promoted denitrifying microbial activity and enhanced the functional potential for nitrogen transformation (p < 0.05). Specifically, biochar provided porous attachment sites and improved mass transfer, while sponge iron supplied readily available Fe²⁺ as an electron donor; their combination buffered iron oxidation and facilitated Fe²⁺-mediated electron transfer. At low temperature, SIB-BS further stimulated extracellular polymeric substances (EPS) secretion, strengthened biofilm stability without causing blockage, and improved the protective interactions between fillers, thereby increasing metabolic efficiency and sustaining TN removal under variable loading. This study provided a technical reference for the efficient denitrification of aquaculture wastewater. Full article

In achieving sustainable development goals, soils play a key role in environmental protection, natural resources, and food security. Peatlands are particularly important here, as they function at the interface between terrestrial and aquatic ecosystems and store large amounts of organic matter. However, organic soils are highly susceptible to transformation and degradation; therefore, their degradation caused by, among others, drainage properties is a high risk to both the environment and agriculture—it disrupts the ecosystems, causes greenhouse gas emissions, and eutrophicates the hydrosphere. Soil degradation in drained peatlands is associated with the transformation of soil organic matter (SOM), which in organic soils is the dominant component of the solid phase of the soil. The aim of our study was to assess the properties and degree of organic matter transformation in drained temperate peatland soils, with particular emphasis on sequential fractionation of SOM and humic acid properties. Due to the fact that in Poland, as many as 90% of non-forest peat bogs have been drained, we compare the mursh horizons that formed after peat bog drainage with the peat horizons that constitute the parent rock (where anaerobiosis occurs and morphological changes in the soil material are absent due to peat bog drainage). Studies were conducted on 11 soil profiles located in central-eastern Poland. Basic physicochemical soil properties were determined: pH, bulk density, contents of ash, SOM, total carbon (TC), and total nitrogen (TN). Sequential carbon fractionation was used to qualitatively analyze organic matter, which allowed for the identification of labile fractions, lipid fractions, humic substances (fulvic and humic acids), and residual fractions. Humic acids (HAs) were extracted using the Schnitzer method and analyzed for their elemental composition and spectrometric parameters in the VIS range. It was demonstrated that SOM transformation in drained temperate peatland soils was correlated with comprehensive changes in the soil’s physical and chemical properties. Compared to peat horizons, topsoil horizons were characterized by higher ash content and density, lower SOM content, and a lower TC/TN ratio. Qualitative SOM transformation during aerobic SOM transformation after draining the studied peatlands consisted of an increase in the amount of labile fractions and humic substances and a decrease in the lipid and residual fractions. The research results have shown that the HAs properties depended on the depth. HAs from topsoil horizons, compared to peat horizons, were characterized by a lower “degree of maturity,” as reflected by the values of atomic ratios (H/C, O/C) and absorbance coefficients (A_4/6 and ΔlogK). It was found that the share of the distinguished SOM fractions and HAs properties were closely correlated with the physical and chemical properties of the soils. The study demonstrated the usefulness of the sequential carbon fractionation method for assessing the effects of dewatered peat transformation. The obtained results could contribute to the development of good practices ensuring high quality of organic matter and stability of ecosystems, as well as to the development of methods for limiting the mineralization of organic matter (SOM), greenhouse gas emissions, and the loss of organic soils in agricultural areas. Full article

Artificial cyanobacterial crusts (ACCs) are a potentially effective biological strategy for combating desertification. However, while functional microorganisms influence ACCs formation efficiency, research on their role is limited, and their underlying promotion mechanisms remain unclear. Here, we investigated the effects of three functional synthetic microbial communities (SynComs), each dominated by microorganisms specialized in exopolysaccharide (EPS) production (3 strains), siderophore production (3 strains), or nitrogen fixation (4 strains), on ACCs formation following inoculation with Microcoleus vaginatus. This study was carried out in a controlled laboratory setting with a 12 h light/dark cycle and a light intensity of 2400–2700 lux. Following a 24-day cultivation period, EPS-producing or nitrogen-fixing SynComs significantly increased the chlorophyll-a content by 16.0–16.3%. Except for the nitrogen-fixing bacteria treatment, other SynComs enhanced the soil organic matter content of ACCs by 9.1% to 27.3%. The content of EPS was significantly improved by all three SynComs by 14.1~19.2%. Urease activity rose by 6.7% when siderophore-producing bacteria were added. The impacts of SynComs on ammonium nitrogen (NH₄⁺-N) showed different temporal dynamics: nitrogen-fixing SynComs significantly increased NH₄⁺-N early (≤10 days), while EPS-producing and siderophore-producing SynComs enhanced accumulation later (17–24 days). SynComs inoculation markedly accelerated cyanobacterial and general microbial colonization and growth. In comparison to day 0, the 16S rRNA gene copy number of ACCs increased by 24.1% and 43.0%, respectively, in the EPS-producing and nitrogen-fixing SynComs. Additionally, correlation analysis showed that SynComs transformed the weak correlations in the control into a strong positive correlation between NH₄⁺-N and both Chl-a and microbial biomass. Our findings demonstrate SynComs, particularly the EPS-producing or nitrogen-fixing SynComs, enhance ACCs formation through elucidated mechanisms, providing a theoretical basis for optimizing ACCs-based desertification control strategies. Full article

Integrated multi-trophic aquaculture (IMTA) has emerged as an ecological intensification strategy capable of enhancing nutrient utilization and improving environmental stability in mariculture systems, yet the microbial mechanisms driving nutrient transformations remain insufficiently understood. This study investigated how culture mode (IMTA vs. monoculture) shape water quality, sediment microbial communities, and nutrient cycling processes in a shrimp–sea urchin system by combining water-quality monitoring, nutrient analysis, 16S rRNA high-throughput sequencing, and redundancy analysis. IMTA significantly increased turbidity, chlorophyll-a, phosphate, ammonium, and nitrite compared with monoculture, while physico-chemical parameters remained stable. Sediment microbiota in IMTA exhibited substantially higher alpha diversity and showed a clear compositional separation from monoculture communities. At the genus level, IMTA sediments were enriched in Vibrio, Motilimonas, and Ruegeria, distinguishing them from monoculture systems. At the phylum level, IMTA was characterized by increased abundances of Proteobacteria and Bacteroidota, accompanied by a marked decline in Spirochaetota. Functional predictions indicated that microbial communities were predominantly characterized by pathways related to amino acid and carbohydrate metabolism, as well as nutrient remineralization. RDA and correlation analyses further identified turbidity, chlorophyll-a, phosphate, ammonium, and nitrite as the principal drivers of microbial divergence. Overall, the findings demonstrate that IMTA reshapes sediment microbial communities toward more efficient nutrient-processing assemblages, thereby promoting active nitrogen and phosphorus transformations and improving biogeochemical functioning relative to monoculture. These results provide mechanistic insight into how IMTA supports nutrient recycling and environmental sustainability in modern mariculture systems. Full article

Titanium (Ti) and its alloys are widely used in biomedical applications due to their biocompatibility and corrosion resistance; however, surface modifications are required to enhance biological functionality. Surface functionalization using natural biomolecules has emerged as a promising strategy to improve early cell–surface interactions and biocompatibility of implant materials. In this study, Ti6Al4V alloy surfaces were biofunctionalized using Spirulina platensis (S. platensis) biomass and protein extract to evaluate morphological, chemical, and biological effects. The functionalization process involved activation with piranha solution, silanization with 3-aminopropyltriethoxysilane (APTES), and subsequent biomolecule immobilization. Surface characterization by scanning electron microscopy (SEM), inductively coupled plasma mass spectrometry (ICP-MS), energy-dispersive X-ray spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR) confirmed the successful incorporation of microalgal components, including nitrogen-, phosphorus-, and oxygen-rich organic groups. Biomass-functionalized surfaces exhibited higher phosphorus and oxygen content, while protein-coated surfaces showed nitrogen-enrich chemical signatures, reflecting the distinct molecular compositions of the immobilized biomolecules. Cell adhesion assays demonstrated enhanced early cell attachment on biofunctionalized surfaces, particularly in samples functionalized with 5 g/L biomass for three hours, which showed significantly greater cell attachment than both the control and protein-treated samples. These findings highlight the complementary yet distinct roles of S. platensis biomass and protein extract in modulating surface chemistry and cell–material interactions, emphasizing the importance of tailoring biofunctionalization strategies to optimize early biological responses on titanium-based implants. Full article

In this study, the effects of electric-field intensity on N transformation during aerobic composting of biochar/pig manure were investigated. Four experimental groups were established under different applied voltages: 0 V (Group CK); 2 V (Group L); 4 V (Group M); and 5 V (Group H). The physicochemical properties of compost, as well as the nitrogen content and its existing forms in the compost, were systematically analyzed. The underlying mechanisms were further explored from the microscopic perspective by analyzing the pore structure of biochar and the microbial diversity in compost. The results showed that the total nitrogen content in compost increased by 5.66–20.87% with the application of the electric field. Cumulative NH₃ emissions decreased by 37.43%, 31.35%, and 40.95% in groups L, M, and H, respectively, while the NO₂ content decreased by 40.73%, 87.93%, and 94.44%, respectively, reducing the N losses during composting. The electric field significantly promoted the migration of nutrients from the compost to the surface of cotton stalk biochar. It also enhanced the microporous structure and adsorption capacity of cotton stalk biochar, thereby facilitating interfacial deposition and N immobilization. The amplification and sequencing of 16S rRNA gene further revealed that Ruminofilibacter, norank_f_MWH-CFBk5, and HN-HF0106 were the key bacterial genera affecting the gas emissions during aerobic composting. Among them, Ruminofilibacter and HN-HF0106 promoted the emission of N₂O, while norank_f_MWH-CFBk5 and Planktosalinus reduced NH₃ emission. This finding indicates that the electric field regulated N transformation and promoted N retention in compost by inhibiting the reproduction of denitrifying bacteria and increasing the abundance of nitrifying and nitrogen-fixing bacteria. This study confirms that electric field and biochar synergistically affect the nitrogen immobilization and waste resource utilization by optimizing the metabolic pathways of microorganisms and the structural characteristics of biochar. Full article