Search Results (123)

Increasing the discharge of saline wastewater from an industrial field poses a challenge for applicable Anammox-based technologies. This study established the integrated partial sulfur-driven denitrification and Anammox (SPDA) system to explore the effects of different salinity levels on nitrogen conversion features. The results of batch tests suggested that sulfur-driven denitrification exhibited progressive suppression of nitrate reduction (97.7% → 12.3% efficiency at 0% → 4% salinity) and significant nitrite accumulation (56.4% accumulation rate at 2% salinity). Anammox showed higher salinity tolerance but still experienced drastic TN removal decline (97.6% → 17.3% at 0% → 4% salinity). Long-term operation demonstrated that the SPDA process could be rapidly established at 0% salinity and stabilize with TN removal efficiencies of 98.1% (1% salinity), 72.8% (2% salinity), and 70.2% (4% salinity). The robustness of the system was attributed to the appropriate strategy of gradual salinity elevation, the promoted secretion of protein-dominated EPS, the salinity-responsive enrichment of Sulfurimonas (replacing Thiobacillus and Ferritrophicum) as sulfur-oxidizing bacteria (SOB), and the sustained retention and activity of Brocadia as AnAOB. The findings in this study deepen the understanding of the inhibitory effects of salinity on the SPDA system, providing a feasible solution for saline wastewater treatment with low cost and high efficiency. Full article

The snakes from the genus Bothrops are responsible for most of the ophidic accidents in Brazil, and Bothrops atrox represents one of these species. Envenomation by these snakes results in systemic effects and is often associated with early mortality following snakebite incidents. The present study investigates the pharmacological properties of Bothrops atrox venom (VBA), focusing specifically on its impact on renal blood flow. Following the renal perfusion procedure, kidney tissues were processed for histopathological examination. Statistical analysis of all evaluated parameters was conducted using ANOVA and Student’s t-test, with significance set at p < 0.005. Administration of VBA resulted in a marked reduction in both perfusion pressure and renal vascular resistance. In contrast, there was a significant elevation in urinary output and glomerular filtration rate. Histological changes observed in the perfused kidneys were mild. The involvement of nitric oxide in the pressor effects of Bothrops atrox venom was not investigated in renal perfusion systems or in in vivo models. Treatment with VBA led to elevated nitrite levels in the bloodstream of the experimental animals. This effect was completely inhibited following pharmacological blockade with L-NAME. Based on these findings, we conclude that VBA alters renal function and promotes increased nitric oxide production. Full article

Groundwater contamination by nitrates (NO₃⁻) and nitrites (NO₂⁻) is an urgent problem in rural areas of Eastern Europe, with profound public health and sustainability implications. This paper presents an integrated assessment of groundwater vulnerability and water quality in rural wells in the Ceanu Mare commune, Cluj County, Romania—a representative area of the Northern Transylvania Basin, characterized by diverse geological structures, intensive agricultural activities, and incomplete public water infrastructure. This study combines detailed hydrochemical analyses, household-level studies, and geological context to identify and quantify key factors influencing nitrate and microbial contamination in rural wells, providing a comprehensive perspective on water quality challenges in the central part of Romania. This study adopts a multidisciplinary approach, integrating detailed geotechnical investigations conducted through four strategically located boreholes. These are complemented by extensive hydrogeological and lithological characterization, as well as rigorous chemical and microbiological analyses of nearby wells. The results reveal persistently elevated concentrations of NO₃⁻ and NO₂⁻, commonly associated with inadequate livestock waste management and the proximity of manure storage areas. Microbiological contamination was also frequent. In this study, the NO₃⁻ levels in well water ranged from 39.7 to 48 mg/L, reaching up to 96% of the EU/WHO threshold (50 mg/L), while the NO₂⁻ concentrations varied from 0.50 to 0.69 mg/L, exceeding the legal limit (0.5 mg/L) in 87% of the sampled wells. Ammonium (NH₄⁺) was detected (0.25–0.34 mg/L) in all the wells, below the maximum allowed limit (0.5 mg/L) but indicative of ongoing organic pollution. All the well water samples were non-compliant for microbiological parameters, with E. coli detected in 100% of cases (5–13 CFU/100 mL). The regional clay–marl substrate offers only limited natural protection against pollutant infiltration, primarily due to lithological heterogeneity and discontinuities observed within the clay–marl layers in the study area. This research delivers a replicable model for rural groundwater assessment and addresses a critical gap in regional and European water safety studies. It also provides actionable recommendations for sustainable groundwater management, infrastructure development, and community risk reduction in line with EU water directives. Full article

Substantial boosts in the low-energy nano-oxygenation of incoming process water were achieved at a municipal wastewater treatment plant (WWTP) upstream of activated sludge (AS) aeration lanes on a single-pass basis by means of an electric field nanobubble (NB) generation method (with unit residence times of the order of just 10–15 s). Both ambient air and O₂ cylinders were used as gas sources. In both cases, it was found that the levels of dissolved oxygen (DO) were maintained far higher for much longer than those of conventionally aerated water in the AS lane—and at DO levels in the optimal operational WWTP oxygenation zone of about 2.5–3.5 mg/L. In the AS lanes themselves, there were also excellent conversions to nitrate from nitrite, owing to reactive oxygen species (ROS) and some improvements in BOD and E. coli profiles. Nanobubble-enhanced Dissolved Air Flotation (DAF) was found to be enhanced at shorter times for batch processes: settlement dynamics were slowed slightly initially upon contact with virgin NBs, although the overall time was not particularly affected, owing to faster settlement once the recruitment of micro-particulates took place around the NBs—actually making density-filtering ultimately more facile. The development of machine learning (ML) models predictive of NB populations was carried out in laboratory work with deionised water, in addition to WWTP influent water for a second class of field-oriented ML models based on a more narrow set of more easily and quickly measured data variables in the field, and correlations were found for a more facile prediction of important parameters, such as the NB generation rate and the particular dependent variable that is required to be correlated with the efficient and effective functioning of the nanobubble generator (NBG) for the task at hand—e.g., boosting dissolved oxygen (DO) or shifting Oxidative Reductive Potential (ORP). Full article

Copper nanoparticles (CuNPs) are increasingly used in agriculture either alone or in combination with pesticides. Recognizing the potential hazards of CuNPs in soil environments, our study evaluated their effects on the metabolic activity of Nitrobacter winogradskyi ATCC 2539, a chemolithoautotrophic bacterium crucial for the nitrification process, which involves the oxidation of nitrite to nitrate in soil ecosystems. This study evaluated the effects of concentration ranges of CuNPs (2.5 to 162.7 mg L⁻¹), CuONPs (3.2 to 203.6 mg L⁻¹), and various pesticides (iprodione, carbendazim, and 2,4-D) and their derivatives (3,5-dichloroaniline, catechol, and 2,4-dichlorophenol) at concentrations ranging from 0.04 to 2.56 mM. CuSO₄ was also used as a control for comparative purposes. Our findings indicated that the CuNPs significantly inhibited the metabolic activity of N. winogradskyi, resulting in a reduction of up to 95% at concentrations of ≥2.5 mg L⁻¹. The CuONPs were less toxic, while the pesticides and their derivatives generally showed lower toxicity. Notably, combinations of CuNPs with pesticides or their derivatives maintained high toxicity levels comparable to those of the CuNPs alone. According to the Loewe additivity model, these effects were largely additive and primarily associated with CuNPs or CuONPs. Protein profiling using matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF)/TOF mass spectrometry (MS) revealed that carbendazim induced noticeable changes in protein profiles. These findings underscore the detrimental impacts of CuNPs and CuONPs on the metabolic activity of N. winogradskyi, posing a considerable risk to the health of agricultural soils. Overall, this research provides crucial insights into the risks associated with using CuNPs in agriculture, particularly regarding their potential threat to nitrifying microorganisms in soils. Full article

Lemon co-products are valuable due to their high dietary fibre, making them significant for valorisation. This research aimed to characterise an innovative lemon dietary fibre (LDF) obtained through integrated extraction (of essential oil, phenolic compounds (PCs), and pectin) by evaluating its chemical, physicochemical, structural, techno-functional, total phenolic content, and antioxidant and antibacterial properties. The effects of incorporating LDF (3% and 6%) into mortadella, a bologna-type sausage, on chemical, physicochemical, technological, and sensory properties were analysed. LDF exhibited a total dietary fibre content of 85.79%, mainly insoluble (52.55%). Hesperidin (89.97–894.44 mg/100 g DW) and eriocitrin (68.75–146.35 mg/100 g DW) were the major free PCs. The major bound PCs were vanillin (5.90–9.16 mg/100 g DW) and apigenin-7-O-glucoside (8.82 mg/100 g DW). This functional ingredient demonstrated antioxidant and antibacterial activity. LDF significantly influenced mortadella’s colour, texture, and mineral composition. Higher levels of LDF result in a paler colour and increased hardness and contribute to reducing sodium levels of the final product. It also decreased residual nitrite levels, although this reduction was followed by a slight increase in lipid oxidation, which remained below the rancidity threshold (≥1.0), ensuring acceptable product quality. Sensory evaluation revealed positive feedback, favouring the 3% LDF formulation. Full article

This study investigated the beneficial effects of individual and co-inoculation with Lactobacillus delbrueckii subsp. lactis N102 and Lactobacillus sakei H1-5 on improving safety parameters, sensory characteristics, and non-volatile metabolite profiles in dry-fermented sausages. Comprehensive analyses were conducted throughout the 20-day maturation period (0, 6, 13, 16, and 20 days), including physicochemical monitoring (moisture content, malondialdehyde (MDA) levels, biogenic amine concentrations, and sodium nitrite residues); sensory evaluation (color parameters and textural properties); and ¹H NMR-based metabolomic profiling. Key findings revealed strain-specific advantages: the N102 inoculation significantly delayed lipid oxidation, achieving the lowest final MDA concentration (4.5 mg/kg) among all groups. Meanwhile, H1-5 supplementation notably improved color attributes (a*/b* ratio = 1.34). The co-inoculation strategy demonstrated synergistic effects through (1) accelerated acidification (pH 5.3 by day 6); (2) enhanced textural properties (significantly increased hardness and elasticity vs. control); (3) optimized water distribution (free water reduced to 0.56% with 64.73% immobilized water); and (4) a significant reduction in sodium nitrite residues (70% decrease) and complete elimination of phenylethylamine (total biogenic amines: 702.94 mg/kg). ¹H NMR metabolomics identified 30 non-volatile metabolites, and the co-inoculation significantly increased the amount of essential amino acids (leucine, isoleucine), flavor-related compounds (glutamic acid, succinic acid), and bioactive substances (gooseberry, creatine). These metabolites enhanced antioxidant capacity, freshness, and nutritional value. Our findings demonstrate that strategic co-cultivation of food-grade lactobacilli can synergistically enhance both the techno-functional properties and biochemical composition of fermented meat products, providing a viable approach for quality optimization in industrial applications. Full article

Growing evidence supports the use of nitrate-reducing bacterial strains as probiotics to enhance the benefits of nitrate metabolism for both oral and systemic health. This study aimed to test the nitrate reductase activity of Levilactobacillus brevis CD2 (DSM-27961/CNCM I-5566), a strain widely used as a starter culture in fermented foods and recognized for its multifaceted health-promoting probiotic properties. We also sought to determine whether the probiotic lysate enhances nitrate reduction ex vivo using six salivary samples from healthy subjects while evaluating its potential influence on pH and buffering capacity. Considering the established link between lactate metabolism and nitrite production, we assessed the salivary levels of D-lactate after a 3-hour incubation with or without Lv. brevis. The results indicate that Lv. brevis CD2 exhibits significant intrinsic and concentration-dependent nitrate reductase activity. Additionally, treatment with Lv. brevis for 3 h significantly increased nitrite generation across all saliva samples, with further enhancement observed after the addition of exogenous nitrates. Lv. brevis also significantly improved salivary pH and buffering capacity, particularly when combined with nitrate. Furthermore, the probiotic treatment resulted in reduced levels of salivary D-lactate. To further support and validate our in vitro and ex vivo findings, we evaluated the oral nitrate-reducing activity in saliva samples from healthy individuals treated for four weeks with Lv. brevis CD2 lozenges. Of note, the results indicated that the probiotic group showed a significant increase in oral nitrate-reducing capacity compared to baseline and placebo after four weeks of treatment. Overall, our study suggests that Lv. brevis CD2 acts as a nitrate-reducing probiotic, providing new insights into its health benefits and complementing findings from previous studies. Full article

Hyperthermia and nitrogenous pollutants like ammonia and nitrite are common risk factors that adversely affect fish health and pose significant threats to the aquaculture industry. However, the impacts of high temperatures on the accumulation of nitrogenous pollutants in the water of the aquaculture systems and their toxicity to farmed fish are not well understood. In this study, juvenile largemouth bass (Micropterus salmoides, LMB) were kept at 28 °C and 34 °C in a closed aquatic system to investigate the effects of higher temperatures on ammonia and nitrite accumulation. The fish were fed 2% of their body weight daily for a 14-day experiment. Ammonia levels gradually increased, peaking on day 7 at 34 °C and on day 9 at 28 °C, then decreased to near zero. Nitrite levels remained low initially and increased rapidly along with the reduction in ammonia levels at both temperatures. The 34 °C high temperature accelerated the accumulation of ammonia and its transformation into nitrite compared to 28 °C. Fish were sampled on day 1 (low ammonia and low nitrite, LALN), day 8 (high ammonia and low nitrite, HALN), and day 14 (low ammonia and high nitrite, LAHN) to explore toxic effects. Successive exposure to high levels of ammonia and nitrite caused oxidative stress in the liver and significant pathogenic changes in the liver and spleen, with more pronounced impacts observed at 34 °C. Significant changes in gene expression were detected in the liver and spleen of fish sampled at HALN and LAHN, compared to those at LALN, with upregulated genes primarily associated with extracellular matrix (ECM) and cytoskeleton organization. A second experiment was conducted at the same temperatures but without ammonia/nitrite accumulation. The results of this experiment confirmed the combined effects of hyperthermia and ammonia/nitrite toxicity on the expression of genes involved in ECM–receptor interaction and TGF-beta signaling. These findings are valuable for optimizing cultivation environments and promoting the health of farmed LMB. Full article

Microplastics and heavy metal contamination frequently co-occur in stormwater filtration systems, where their interactions may potentially compromise nitrogen removal. Current research on microplastics and Cd contamination predominantly focuses on soils and constructed wetlands, with limited attention given to stormwater filtration systems. In this study, the single and synergistic effects of aged polyethylene microplastics (PE) and cadmium (Cd) contamination in stormwater infiltration systems were investigated from perspectives of nitrogen removal, microbial community structures, and predicted functional genes in nitrogen cycling. Results showed that PE single contamination demonstrated stronger inhibition on NO₃⁻–N removal than Cd. Low-level PE contamination (PE content: 0.1% w/w) in Cd-contaminated systems showed stronger inhibitory effect than high-level PE contamination (PE content: 5% w/w). The mean NO₃⁻–N removal efficiency under combined Cd50 (Cd concentration: 50 μg/L) and PE5 contamination during the sixth rainstorm event was 1.04 to 34.68 times that under other contamination scenarios. Metagenomic analysis identified keystone genera (Saccharimonadales, Enterobacter, Aeromonas, etc.), and critical nitrogen transformation pathways (nitrate reduction to ammonium, denitrification, nitrogen fixation, and nitrification) govern system performance. PE and Cd contamination effects were most pronounced on nitrification/denitrification enzymes beyond nitrite oxidase and nitrate reductase. These mechanistic findings advance our understanding of co-contaminant interactions in stormwater filtration systems. Full article

Vegetables, as an important source of vitamins and minerals, are highly recommended in a healthy diet. At the same time, vegetables can contain elevated amounts of nitrates and nitrites, which are the possible nitrosating agents responsible for the formation of carcinogenic nitrosamines. In young children, they can cause methemoglobinemia. Determining the level of nitrates and nitrites, as well as the possible reduction in their concentrations during culinary processing, is especially important for the diet of young children, who are introduced to leafy vegetables during the first year. For some types of vegetables that are often found in the diet, maximum permissible concentrations have not yet been established. Our goal was to estimate the reduction factors of nitrates and nitrites and suggest the best ways to properly prepare foods. For this purpose, samples of Swiss chard, spinach, and white cabbage were collected from the market to determine the nitrate and nitrite content. Vegetable samples were subjected to culinary preparations: soaking, cooking, and a combination of soaking and cooking. Quantitative and qualitative determination of nitrates and nitrites in vegetables was carried out on high-performance liquid chromatography (HPLC) equipped with a diode array detector (DAD). The obtained results showed that the highest nitrate concentrations were in Swiss chard samples, followed by spinach, and the lowest in white cabbage samples. The impact of culinary preparation was highest on spinach samples. Considering the average nitrate concentrations achieved after cooking or soaking and cooking, there was no risk of exceeding the ADI limit. However, the ADI values would be exceeded at the maximum nitrate concentrations. Full article

Anthropogenic activities significantly threaten aquatic ecosystems, accelerating water quality deterioration through pollution, overexploitation, and habitat disturbance. Roodeplaat Dam in South Africa exemplifies these challenges, experiencing nutrient overload driven by malfunctioning wastewater treatment works (WWTWs), urban runoff, and agricultural activities. This study investigates the spatio–temporal dynamics of flow patterns and nutrient loads in Roodeplaat Dam, focusing on the interplay between nutrient pollution, land use, and land cover change (LULCC). A multi-site sampling approach was employed to assess total phosphorus (TP) and nitrate–nitrite (NO₃ + NO₂) loading, complemented by geospatial analysis of LULCC impacts over two decades. The study revealed that TP and NO₃ + NO₂ concentrations surpassed permissible limits at certain monitoring sites, particularly downstream of WWTWs during low-flow periods, demonstrating their substantial role in elevating nutrient levels. The study further revealed that extensive human-driven changes in the catchment area were key contributors to nutrient dynamics. These changes included a reduction in vegetation cover from 65% to 45.17%, an increase in soil exposure from 10.25% to 22.01%, and urban expansion from 26.56% to 32.32%. These alterations disrupt natural nutrient cycles, leading to increased runoff and potential eutrophication of water bodies. Thus, to address these challenges, this study underscores the need for an integrated strategy that combines nature-based solutions, enhanced wastewater treatment, stricter regulatory compliance, and adaptive management to mitigate pollution and improve water resource sustainability. The insights gained from this case study provide valuable guidance for managing similar systems in developing regions under increasing anthropogenic and climatic pressures. Full article

The removal of surface residues from single-layer graphene (SLG), including poly(methyl methacrylate) (PMMA) polymers and Cl⁻ ions, during the transfer process remains a significant challenge with regard to preserving the intrinsic properties of SLG, with the process often leading to unintended doping and reduced electronic performance capabilities. This study presents a rapid and efficient surface treatment method that relies on an aqueous sodium nitrite (NaNO₂) solution to remove such contaminants effectively. The NaNO₂ solution rinse leverages reactive nitric oxide (NO) species to neutralize ionic contaminants (e.g., Cl⁻) and partially oxidize polymer residues in less than 10 min, thereby facilitating a more thorough final cleaning while preserving the intrinsic properties of graphene. Characterization techniques, including atomic force microscopy (AFM), Kelvin probe force microscopy (KPFM), and X-ray photoelectron spectroscopy (XPS), demonstrated substantial reductions in the levels of surface residues. The treatment restored the work function of the SLG to approximately 4.79 eV, close to that of pristine graphene (~4.5–4.8 eV), compared to the value of nearly 5.09 eV for conventional SLG samples treated with deionized (DI) water. Raman spectroscopy confirmed the reduced doping effects and improved structural integrity of the rinsed SLG. This effective rinsing process enhances the reproducibility and performance of SLG, enabling its integration into advanced electronic devices such as organic light-emitting diodes (OLEDs), photovoltaic (PV) cells, and transistors. Furthermore, the technique is broadly applicable to other two-dimensional (2D) materials, paving the way for next-generation (opto)electronic technologies. Full article

Nitric oxide (NO) functions as a signaling molecule in plant adaptation to changing environmental conditions. NO levels were found to increase in plants in response to low temperatures (LTs). However, knowledge of the pathways involved in enhanced NO production under cold stress is still limited. For this reason, we aimed to determine the role of different NO sources in NO generation in cucumber roots exposed to 10 °C for short (1 d) and long (6 d) periods. The short-term treatment of seedlings with LT markedly increased plasma membrane-bound nitrate reductase (PM-NR) activity and induced the expression of three genes encoding NR in cucumber (CsNR1-3). On the other hand, long-term exposure was related to both increased cytoplasmic NR (cNR) activity and induced expression of the CsARC gene, encoding the amidoxime-reducing component (ARC) protein. The decrease in nitrite reductase (NiR) activity and the higher NO₂⁻/NO₃⁻ ratio in the roots of plants exposed to LTs for 1 d suggest that tissue conditions may favor NR-dependent NO production. Regardless of NR stimulation, a significant increase in NOS-like activity was observed in the roots, especially during the long-term treatment of plants with LT. These results indicate that diverse NO-producing routes, both reductive and oxidative, are activated in cucumber tissues at different stages of cold stress. Full article

Background/Objectives: Our previous study demonstrated that 3-(4-hydroxy-3-methoxyphenyl)propionic acid (HMPA) administration improved grip strength and reduced blood urea nitrogen levels, but its underlying mechanisms remain unclear. This study aimed to investigate the effects of HMPA on oxidative stress and muscle fiber composition, emphasizing its potential role in modulating redox signaling pathways and influencing muscle development. Methods: Eight-week-old male C57BL/6 mice were orally administered HMPA solution (50 or 500 mg/kg/day) or distilled water (10 mL/kg) for 14 days, and then divided into sedentary and exhaustive exercise groups to evaluate oxidative stress status, myosin heavy chain (MHC) isoform expression, and underlying mechanisms. Results: Both low and high doses of HMPA reduced oxidative stress by decreasing plasma reactive oxygen metabolites. High-dose HMPA reduced plasma nitrite/nitrate levels and enhanced antioxidant capacity post-exercise, accompanied by changes in the mRNA abundance of antioxidant enzymes (e.g., Sod1 and Nqo1) and reductions in the mRNA abundance of nitric oxide synthases (e.g., Nos2 and Nos3) in the soleus. Additionally, high-dose HMPA administration increased the protein expression of MYH4 in the soleus, while low-dose HMPA enhanced the gene expression of Myh4 and Igf1, suggesting that HMPA may promote fast-twitch fiber hypertrophy through the activation of the IGF-1 pathway. Furthermore, low-dose HMPA significantly increased the gene expression of Sirt1 and Nrf1, as well as AMPK phosphorylation post-exercise, suggesting low-dose HMPA may improve mitochondrial biogenesis and exercise adaptation. Conclusions: These findings suggest that HMPA may serve as a dietary supplement to regulate redox balance, enhance antioxidant defenses, and promote the formation of fast-twitch fibers. Full article