Search Results (1,583)

Electrospun poly(vinylidene fluoride) (PVDF) nanofiber filters are attractive for particulate air filtration because they combine high filtration efficiency with low airflow resistance. Here, three inorganic additives, namely aluminum chloride (AlCl₃), potassium nitrate (KNO₃), and silicon nitride (Si₃N₄), were investigated using formulation-specific electrospinning conditions selected to achieve stable fiber formation. Although all filters exhibited high initial filtration efficiencies above 96%, clear differences were observed in fiber morphology, pressure drop, electrostatic potential decay, and long-term filtration stability. Among the tested samples, the Si₃N₄-containing filter showed the best long-term performance, retaining approximately 94% filtration efficiency after 30 days, whereas neat PVDF decreased to about 85%. These results suggest that differences in long-term filtration stability are closely associated with charge-retention behavior, and that the incorporation of inorganic additives can influence the durability of PVDF-based electrospun nanofiber air filters. Full article

Coptotermes formosanus is an economically significant termite species with a highly organised caste system, in which division of labour underpins colony function. Although gut microbiota is widely recognised for its roles in host nutrition and adaptation, much less is known about how these microbial communities are structured across castes. To explore caste-related gut bacterial variation in C. formosanus, we analysed the community structure of both workers and soldiers using high-throughput amplicon sequencing targeting the bacterial 16S rRNA gene. Although both castes were dominated by Bacteroidota and Spirochaetota, which together accounted for 78.87% to 85.78% in workers and 63.31% to 84.38% in soldiers, significant caste-associated differences were evident. Workers showed significantly higher bacterial richness, as indicated by observed ASVs, Chao1 indices, and Faith’s PD. Further clear caste-associated bacterial community was revealed by beta-diversity analysis. Differential taxonomic analysis revealed distinct caste-associated enrichment patterns. In addition, co-occurrence network analysis indicated a caste-associated interaction structure, with soldier-biased taxa forming a dense, highly connected module while worker-biased taxa contributed to local structure and bridging positions. Furthermore, chemoheterotrophy and fermentation were predicted to be enriched in workers, whereas nitrate reduction, aerobic chemoheterotrophy, aromatic compound degradation, and phenotypes related to biofilm formation, stress tolerance, and mobile elements were predicted to be relatively enriched in soldiers. Moreover, qPCR analysis further showed caste-associated differences in dominant gut protists, with Pseudotrichonympha in workers significantly higher than in soldiers and positively correlated with Azobacteroides. These results provide clear evidence of caste-associated differentiation in gut microbial composition and offer a foundation for identifying novel microbial targets for termite pest management. Full article

In crisis times, traditional models of water quality assessment and water resources management lose their effectiveness. In the current conditions of local climate change, accidental pollution, emergencies or military operations, there is an urgent need to transition from traditional descriptive hydrochemical monitoring toward intelligent analysis of spatial-temporal datasets. In this paper, the integrated approach combining spatial cluster analysis, GIS-based visualization, and machine learning is proposed for assessing the surface water quality under conditions of limited and incomplete hydrochemical monitoring data. A geospatial assessment of nutrient impacts on surface water quality was conducted using 192 hydrochemical observations collected during the 2024–2025 monitoring period at eight state monitoring stations located in the basins of the Teteriv, Uzh, Irsha, Ubort, Sluch, Hnylopiat, and Voznia rivers, Polissia, Ukraine. Permutation feature importance analysis based on the Random Forest model showed that nitrate concentration accounted for approximately 75% of the total relative importance, whereas phosphate concentration contributed approximately 14%, indicating that these variables were the most informative predictors among the investigated hydrochemical parameters. The latter parameters are associated with dissolved oxygen variability among the analyzed hydrochemical parameters. According to the results of this study, three interpretable groups of monitoring stations were formed: Cluster 1, representing moderate water quality with increased nutrient pressure, Cluster 2, representing comparatively favourable background conditions, and Cluster 3, representing a nitrate-dominated hydrochemical type. The Random Forest model demonstrated limited predictive performance (R² = 0.154), indicating that nutrient-related variables alone explain only a small proportion of dissolved oxygen variability. Hence, additional factors, including hydrological conditions, water temperature, organic matter decomposition, biological productivity, and catchment-specific characteristics, also play an important role in shaping oxygen dynamics. The spatial visualization of cluster membership showed that geographical location alone does not fully determine the surface water quality patterns in Ukrainian Polissia. Instead, the local catchment characteristics and land-use conditions appear to exert a stronger influence on the formation of nutrient-related water quality differences. The authors propose to employ the spatial cluster analysis and machine learning as a basic supporting tool for the transition from retrospective interpretation of hydrochemical monitoring data to predictive and adaptive water resources management. The integration of geospatial analysis and machine learning provides a practical decision-support framework for the early detection of anomalies, identification of potential pollution sources, and prioritization of river sub-basins for implementing nature-based solutions. Full article

Cultivation of L. platensis under elevated CO₂ ensures CO₂ biofixation, while adding Na₂SeO₃ to the culture medium, produces valuable Se-enriched biomass. This study evaluated the effect of Na₂SeO₃ supplementation (20–640 mg/L) on the growth of L. platensis under 3 vol.% CO₂. The cultivation was carried out in 10 L column-type photobioreactors under continuous (24 h·d⁻¹) illumination with intensity of 220 µmol·m⁻²·s⁻¹, a constant temperature of 27 °C and aeration rate of 1 L/min. Two consecutive cultivation cycles (8 days each) were conducted: the first with the original strain and the second with an inoculum adapted to 20 mg/L (taken from the first cycle). The growth rate, cell viability, pH, and the concentrations of nitrates, phosphates, carbonates, bicarbonates, NH₄⁺ ion were investigated. It was established that under intensive cultivation at elevated CO₂, L. platensis is very sensitive to Na₂SeO₃ supplements: concentrations > 160 mg/L led to culture death within the first 2–4 days, while the acute toxicity threshold lies in the range of 80–100 mg/L. The highest biomass growth rate in the 1st and 2nd cycles was achieved in the control (0 mg/L of Na₂SeO₃): 329 and 239 mg·L⁻¹·d⁻¹ dry weight, respectively. At 20 mg/L, the growth rate drops to 289 and 208 mg·L⁻¹·d⁻¹ in the 1st and 2nd cycles, respectively. The percentage of live trichomes at the end of the 1st and 2nd cycles at 20 mg/L was 85 and 67%, respectively, indicating low adaptation capacity even to this concentration of Na₂SeO₃. The addition of Na₂SeO₃ did not lead to significant pH deviations from the control. Nitrates and phosphates consumption slowed down at Na₂SeO₃ concentrations of 40–60 mg/L. Bicarbonate and carbonate ions did not change significantly across all samples due to the maintenance of elevated CO₂ concentration. In a separate experiment under atmospheric CO₂ (0.04%), selenite toxicity was less pronounced than under 3% CO₂, and growth declined after day 4 due to carbon limitation rather than selenite toxicity. Full article

Excessive nitrate discharge causes water eutrophication and public health risks, which has become a core challenge in global water environment governance. Conventional nitrogen removal technologies suffer from limitations such as carbon source dependence and secondary pollution, and can hardly meet the requirements of low-carbon water treatment. Driven by electric energy and free of additional chemical reagents, electrocatalytic nitrate reduction enables flexible regulation of product selectivity. Among all possible reaction pathways, selective N₂ production is the nitrogen removal route with the highest environmental benefits. However, constrained by the high energy barrier of N–N coupling and intense competition from side reactions, achieving highly selective N₂ production remains a major technical difficulty, and most existing reviews in this field focus on ammonia synthesis. This paper systematically reviews the research progress in this field, elucidates the reaction network and nitrogen production mechanism, compares the advantages and disadvantages of three types of selectivity evaluation methods, summarizes the design strategies of multi-scale electrocatalysts, and analyzes how operational parameters (including applied potential, electrolyte composition, pH, etc.) and reactor configuration regulate the reaction selectivity. Finally, the existing challenges are concluded and future development directions are prospected, so as to provide a reference for the research, development and engineering application of electrocatalytic nitrogen removal technology. Full article

Oxidative and nitrosative stress contribute to epileptogenesis and seizure-related neuronal injury through iron-mediated reactive oxygen species generation and excessive nitric oxide production. This study examined whether combining valproate (VALP) with the iron chelator deferoxamine (DFO) produces additional electrophysiological or biochemical effects in a penicillin-induced model of epileptiform activity. Male Wistar rats were assigned to four groups (n = 7/group): penicillin control, VALP (500 mg/kg), DFO (100 mg/kg), and VALP + DFO. Epileptiform activity was induced by intracortical penicillin and monitored by electrocorticography for 180 min, and spike frequency, spike amplitude, serum and hippocampal total antioxidant status, total oxidant status, oxidative stress index, and nitric oxide levels were measured. VALP, DFO, and their combination significantly reduced spike frequency and amplitude versus penicillin. Although VALP + DFO did not further suppress spike frequency or spike amplitude compared with VALP alone, the combination was associated with selected biochemical differences, including lower serum and hippocampal nitrite/nitrate surrogate levels and higher hippocampal total antioxidant status. These findings suggest that VALP + DFO produces selected, marker-specific biochemical changes beyond VALP monotherapy, without providing additional anticonvulsant efficacy in this acute model. The functional significance of these biochemical changes remains to be established. Full article

The large-scale production and utilization of nitrogen-containing compounds have greatly promoted the development of modern agriculture and the chemical industry, but have also resulted in increasingly severe nitrate contamination and an imbalance of the nitrogen cycle. The efficient conversion of nitrate into value-added ammonia not only contributes to pollutant remediation but also provides a promising route for green ammonia synthesis. Owing to its mild reaction conditions, potentially lower environmental impact, and compatibility with renewable electricity, electrocatalytic nitrate reduction to ammonia has attracted considerable attention in recent years. This process involves a multielectron transfer process involving numerous intermediate transformations, and its catalytic performance largely depends on the adsorption and conversion of key intermediates on the catalyst surface, as well as the suppression of the competing hydrogen evolution reaction. This review systematically summarizes recent advances in electrocatalytic nitrate reduction to ammonia, with emphasis on the reaction mechanisms and major reaction pathways, as well as the design strategies, structure–activity relationships, and performance enhancement mechanisms of metal-based, carbon-based, and composite catalysts. In addition, the main challenges in this field, including product selectivity, mass transport, in-situ mechanistic characterization, and long-term stability, are discussed. Finally, the construction of highly efficient catalytic systems and key directions for future research are outlined, with particular emphasis on nitrate valorization and sustainable ammonia synthesis. Full article

In recent years, increasing attention has been paid to limiting the use of nitrates and nitrites in meat products due to concerns regarding their potential health implications. Despite their important technological role in ensuring microbiological safety, oxidative stability, and the development of sensory characteristics of meat products, their use raises health concerns among consumers. These concerns are primarily associated with the potential formation of N-nitrosamines, some of which have been classified possible human carcinogens. In this context, there is growing interest in natural functional additives consistent with the clean-label concept and the zero-waste approach, including raw materials derived from fruit-processing by-products. Fruit-processing by-products, especially berry pomace, are a rich source of phenolic compounds with antioxidant and antimicrobial properties. Current evidence indicates that the bioactive compounds present in berry pomaces effectively reduce lipid oxidation and exhibit antimicrobial potential, which may contribute to inhibiting the growth of undesirable microorganisms in meat products. However, the effectiveness of this activity depends on several factors, including the type of berry pomace, its phenolic profile, the form of application (e.g., powder, extract, or freeze-dried material), the concentration applied, the type of meat product and the storage conditions. Consequently, berry pomaces should be regarded as natural ingredients supporting nitrite reduction strategies in meat products rather than as complete substitutes for nitrites. Furthermore, although berry pomaces exhibit considerable functional potential, their effectiveness in reducing nitrite levels depends on the type of meat product, its formulation, and the applied processing conditions. Among berry pomaces, red currant pomace (Ribes rubrum) has recently attracted increasing scientific interest because of its rich phenolic profile and promising functional properties. However, compared with chokeberry, blueberry, blackberry, and blackcurrant pomaces, relatively few studies have investigated its application in meat products. Therefore, further research is needed to confirm its technological functionality, antimicrobial efficacy, and potential contribution to nitrite-reduction strategies under different meat-processing conditions. Full article

The decomposition of crop residue is indispensable for carbon (C) cycling in agricultural ecosystems, and nitrogen (N) application has a pronounced effect on this by regulating the C/N ratio and microbial growth strategy. This study investigated how different inorganic and organic nitrogen sources interact with soil properties to regulate straw decomposition, nutrient release, microbial community assembly, and microbial interaction networks across typical cropland soils of the North China Plain. Five treatments, i.e., no N addition, urea, calcium nitrate, yeast derivatives, and glutamate, were conducted in fluvo-aquic soil, lime concretion black soil, cinnamon soil, and yellow-cinnamon soil. We found that soil type strongly regulated straw decomposition dynamics, with cumulative decomposition rates varying greatly among the four soil types after 180 days, ranging from 55.78% to 68.75%. In particular, the lime concretion black soil exhibited the highest straw decomposition and C release rates, which harbored higher relative abundances of potential straw-decomposing taxa, including Luteibacter, Chitinophaga, Dothideomycetes, and Leotiomycetes. Bacterial community assembly shifted from stochastic dominance at early stages to deterministic selection at later stages, whereas fungal community assembly remained predominantly stochastic with increasing dispersal limitation during late decomposition. The dominant bacterial phyla were Proteobacteria and Bacteroidota, and the fungal community composition succeeded from Alternaria, Rhizopus, Cladosporium and Meyerozyma to Chaetomium, Schizophecium and Apodus. Compared with no N addition, yeast derivatives significantly increased the straw decomposition rate in fluvo-aquic soil, lime concretion black soil, and cinnamon soil by 15.00, 10.66, and 12.19 percentage points, respectively, within 14 days. This is related to the enhanced complexity of the bacterial co-occurrence network, among which Altererythrobacter, Sphingomonas, Candidatus_Xiphinematobacter, Devosia, and Chitinophaga were identified as key microbial groups. Glutamate stimulated later decomposition by modifying the fungal community structure and strengthening fungal interactions centered on Alternaria and Schizothechium. These findings reveal how N forms regulate straw decomposition through soil-dependent microbial assembly and interaction networks, providing a mechanistic basis for optimizing nitrogen management strategies for efficient straw nutrient recycling. Full article

This study aimed to evaluate the effects of establishing a population of the green microalgae Chlorella sp. on different key aspects of a biofloc culture of Penaeus vannamei in comparison with those obtained with a commercial probiotic. The aspects evaluated were shrimp zootechnical performance, nutritional composition of biofloc and microbial populations of shrimp intestinal microbiota and biofloc. Four treatments were tested: two of them included Chlorella sp. alone (M) or in combination to a bacterial probiotic (MP), while the other two included only the probiotic (P) or none of them (C). The presence of Chlorella sp. enhanced protein and phosphorus bioavailability in the biofloc and contributed to nutrient bioremediation within the system. However, shrimp growth performance and survival were significantly reduced, likely due to greater and more prolonged nitrate exposure following microalgae inoculation. Although overall nitrate and phosphate concentrations were higher in microalgae treatment, their accumulation over the experimental period was lower in the presence of Chlorella sp. In addition, microalgal supplementation reduced the abundance of bacterial groups associated with oligotrophic lifestyles, complex organic matter degradation, and nitrogen cycling in the intestinal microbiota. In contrast, probiotic supplementation increased protein content in shrimp and phosphorus bioavailability in the biofloc, while zootechnical performance remained comparable to the control and was higher than in microalgae treatments. Furthermore, probiotic addition reduced the abundance of Flavobacteriaceae, a bacterial family proposed as a bioindicator of White Feces Syndrome (WFS) in P. vannamei. Full article

Population growth, increasing water demands for data centers, and the need for more sustainable water practices are prompting advancement of next-generation water resource management strategies including water reuse. In the Midwestern United States (U.S.), where non-traditional approaches to augmenting water supply, including water reuse, are relatively new, full advanced water treatment (AWT), which includes microfiltration/ultrafiltration (MF/UF) and reverse osmosis (RO), produces a concentrate stream that is expensive to address (i.e., brine disposal). Carbon-based advanced treatment (CBAT), which combines ozonation, biofiltration, and granular activated carbon, has been shown to be a viable alternative with select advantages over the traditional RO approach, including the lack of brine generation. Two novel pilots were conducted in the Midwestern U.S., one at a large (>100 MGD) and one at a small (~10 MGD) wastewater reclamation facility (WRF), to provide proof of concept that CBAT could meet distinct regional needs. While additional demonstration data are ultimately needed for future regulatory approvals, results from the pilots showed that water quality objectives were met with treated water quality of <0.5 mg/L total Kjeldal nitrogen (TKN), <2 mg/L total organic carbon (TOC), and substantial reduction in constituents of emerging concern (CECs). If nitrate removal is required to meet drinking water standards (10 mg/L), additional treatment optimization at the source WRFs would be required. Areas for further research identified by this effort include mitigating the potential for ozonation to contribute to the formation of disinfection byproducts such as bromate and N-nitrosodimethylamine (NDMA). Along with the treatment performance demonstrated at these pilots, the study provided an opportunity to engage with key stakeholders to build trust in the AWT approach, which is critically important for regulatory and public acceptance. Based on two field-scale pilot studies in the U.S. Midwest, this paper analyzes CBAT application advantages and challenges in municipal water reuse and identifies research directions for the industry. Full article

The aim of this study was to determine the effect of using Swiss chard powder (SCP) and pre-converted SCP as alternative nitrate and nitrite sources in sucuk (a Turkish dry fermented sausage) production on the growth of Listeria monocytogenes and some quality characteristics of the product. Sucuk batters were prepared based on four different curing applications (synthetic nitrate; SCP; synthetic nitrite; pre-converted SCP). The batters were inoculated with L. monocytogenes at a level of 10⁴ cfu/g. Sucuk groups containing nitrate were subjected to slow ripening, while sucuk groups containing nitrite were subjected to rapid ripening. After 3 days of fermentation, in both rapid and slow ripening, the groups containing SCP and pre-converted SCP showed higher pH values than the groups containing synthetic nitrate and nitrite. At the end of ripening, the a_w value was found to be below 0.90 in all groups. SCP or pre-converted SCP did not have a significant effect on residual nitrite content. Lactic acid bacteria showed good growth in all four groups. Lower Micrococcus/Staphylococcus counts were observed in rapid ripening compared to slow ripening. As ripening time progressed, the number of L. monocytogenes decreased in all groups, with a mean reduction of 1.23 log cfu/g. At the end of ripening, no difference was observed between the groups in terms of L. monocytogenes count. As a result, SCP or pre-converted SCP showed similar results to synthetic curing agents in the inhibition of L. monocytogenes in sucuk. In addition, these natural products did not cause significant changes in the overall characteristics of the product. Full article

Freshwater phytoplankton communities are currently being influenced by ongoing climate change. This study aimed to investigate the effects of warming and dissolved inorganic carbon (DIC) on chlorophyll-a concentration and physicochemical variables in a freshwater ecosystem in mesocosm conditions. A 21-day experiment was conducted using freshwater collected from the Tigris River. Four treatments were established: control, warming (+3 °C), DIC, and DIC + 3 °C, with three replicates for each treatment. Chlorophyll-a, DIC, water temperature, pH, dissolved oxygen (DO), nitrate (NO₃⁻), and phosphate (PO₄³⁻) were measured throughout the experiment. The results showed that chlorophyll-a concentration increased under warming and DIC treatments. The combined treatment (DIC + 3 °C) showed the highest chlorophyll-a concentration. Water temperature was significantly higher in the warming treatment compared to DIC treatment. In addition, pH, DO, nitrate, and phosphate varied among treatments and over time. Overall, the combined effects of warming and DIC were greater than those of the individual treatments. These findings indicate that warming and increased inorganic carbon availability may play an important role in influencing chlorophyll-a concentration, carbon cycling, nutrient dynamics, and water quality in freshwater ecosystems. Full article

Reactive oxygen and nitrogen species (RONS) generated by medical gas plasmas are considered major mediators of plasma-induced biological effects. This includes the atmospheric pressure argon plasma jet kINPen routinely used in clinical applications. The jet’s biomedical action has been shown to be tailored by modifying its feed gas. However, a systematic comparison of how feed gas composition and humidity shape plasma chemistry remains lacking, which would shift application-specific plasma chemistries from guessing to designing. In this study, we systematically investigated, compared, and statistically related 65 individual feed gas conditions of the kINPen argon plasma jet by increasing O₂, N₂, and combined O₂ + N₂ admixtures under dry and humidified conditions. Plasma gas phases were assessed using optical emission spectroscopy and reactive species produced in liquid via hydrogen peroxide, nitrite, and nitrate quantification. O₂-containing admixtures generally reduced overall plasma emission and liquid-phase RONS accumulation, whereas N₂-containing admixtures preferentially enhanced nitrogen-associated emission features. Water vapor addition via the admixture gas stream acted as an important secondary tuning parameter, exerting the strongest effects under combined O₂ + N₂ conditions. Multivariate analyses confirmed clear separation of chemistry profiles according to feed gas composition and humidity, while correlation and regression analyses identified several condition-dependent relationships between gas-phase emissions and liquid-phase reaction products. These data provide a comprehensive characterization of kINPen plasma chemistry under controlled feed gas modification and establish a reference framework for tailoring plasma-derived reactive species profiles in future plasma biology and medicine studies. Full article

To investigate the effects of red–blue–green light ratios on the growth, photosynthesis, nutritional quality, and mineral nutrient accumulation of hydroponic lettuce, a controlled experiment was conducted using the deep flow technique (DFT) system. Four light treatments were applied under a constant photosynthetically active radiation of 350 μmol·m⁻²·s⁻¹: the red–blue light control (CK, R:B = 60:40) and 10% (T1), 20% (T2), and 40% (T3) green light substitution treatments. Growth, photosynthetic characteristics, quality and nutrient indexes were assessed. The results showed that 40% green light (T3) significantly enhanced biomass production, increasing the fresh and dry weights by 33.16% and 21.40%, respectively, compared with the CK (control). In addition, the soluble sugar and vitamin C contents increased by 61.79% and 13.43%, respectively, while the nitrate content decreased by 16.31%. T1 (10% green light) was the most effective at promoting antioxidant compound accumulation, resulting in 148.61% and 81.24% increases in the flavonoid and polyphenol contents. All green light treatments increased the net photosynthetic rate and transpiration rate while decreasing the intercellular CO₂ concentration and stomatal conductance. Green light supplements generally promoted phosphorus and magnesium uptake, and T3 remarkably enhanced the total accumulation of major mineral elements in shoots. In conclusion, 40% green light substitution optimizes both the biomass and nutritional quality of lettuce, whereas 10% substitution significantly promotes antioxidant accumulation. These findings provide valuable insights for optimizing light spectra in controlled environments for hydroponic lettuce production. Full article