Nitrite Oxidation Research Articles

Enhancement mechanism of biocathodes on nitrification in the bioelectrochemical system from a microbial perspective

Biocathodes in bioelectrochemical systems (BESs) have been reported to enhance nitrogen (N) removal. However, the complex multi-parameter variables in BESs have increased the difficulty of studying the enhanced mechanism of nitrification using biocathodes. This study aimed to construct a range of potentiostatic biocathodes (−400, −200, ＋200, and ＋400 mV vs Ag/AgCl) with a dissolved O2 concentration of 2–3 mg L−1 using a potentiostat to further clarify the mechanism. The mechanism of how biocathodes influence microorganisms was elucidated from multiple perspectives, including variations in N concentration, electrochemistry, high-throughput sequencing, and PICRUSt2 prediction. The biocathodes were found to increase the nitrification rate by improving the abundance of nitrification-related bacteria (unidentified_Nitrospiraceae, Thauera, Nitrosomonas, Prosthecobacter, and Stenotrophomonas), the expression of genes related to ammonia oxidation and nitrite oxidation (pmoABC, hao, nirk, ncd2, and npd), and the activity of ammonia oxidase (AMO) and nitrite oxidase (NOR) in the biocathodes. The results of this study might provide crucial academic support and demonstration in facilitating the application of BESs and realizing the deep treatment of wastewater.

Ag nanoparticles-decorated CuBi2O4-rGO electrodes as an amperometric sensor for electrochemical determination of nitrite

There is an increasing demand for developing more sensitive sensors for determining nitrite, which has potential use in wastewater, food preservatives, and corrosion inhibitors. Here, we designed a CuBi2O4/rGO nanocomposite via simultaneous electrochemical deposition of GO and CuBi2O4. Then, the nanocomposite surface was electrochemically functionalized with Ag nanoparticles. Analytical and morphological characterizations showed that nanocomposites were synthesized with high purity and crystallinity. Finally, the electrocatalytic activity of the prepared Ag@CuBi2O4/rGO electrode was investigated as an electrochemical sensor application in nitrite detection. Ag@CuBi2O4/rGO had a higher faradaic current than CuBi2O4/rGO and PGE. The modified electrode exhibited high selectivity with low nitrite oxidation potential (+ 0.8 V) and detection limit (0.18 µM). The detection limit for nitrite is lower than that of most reported materials.

Effect of Sulfide on the Processes of Transformation of Nitrogen Compounds and the Microbial Community Composition in the Anammox Bioreactor

Anammox is one of the most important processes in the global nitrogen cycle and the basis for an efficient technology of nitrogen removal from wastewater. The effect of the presence of sulfide in wastewater on the transformation of nitrogen compounds by the anammox community has been insufficiently studied. The present work dealt with the effect of sulfide on nitrogen removal efficiency and the dynamics of nitrogen species in a laboratory sequencing batch bioreactor modeling the functioning of the anammox community carrying out ammonium oxidation via nitritation and anammox and nitrite oxidation. The 16S rRNA gene profiling of the community of the anammox-activated sludge attached to the stationary carrier revealed members of the key physiological groups: ammonium oxidizers of the genus Nitrosomonas, nitrite oxidizers of the genus Nitrosospira, and anammox bacteria of the genera Candidatus Brocadia and Ca. Jettenia, as well as members of other bacterial genera. Nitrate removal was not sensitive to sulfide at concentrations up to 50 mg S/L and decreased by 17% at 100 mg/L. The threshold of sulfide sensitivity for group I nitrifiers was ~50 mg/L, while anammox bacteria were resistant to sulfide concentrations of up to 100 mg S/L in the incoming water. Group II nitrifiers were probably the most sulfide-sensitive components of the community. A drastic increase in the abundance of members of the family Hydrogenophilaceae at elevated sulfide concentrations, together with the precipitation of elemental sulfur, may indicate sulfide oxidation either by molecular oxygen or via nitrate reduction; this finding requires further investigation. This is the first report on the different effects of sulfide on the growth rate of members of the nitrifying genus Nitrosomonas, increasing/decreasing or not affecting it for different phylotypes at elevated sulfide concentrations.

Quinic acid ameliorates ulcerative colitis in rats, through the inhibition of two TLR4-NF-κB and NF-κB-INOS-NO signaling pathways.

In this study, the therapeutic effect of quinic acid (QA), which has anti-inflammatory activity, was investigated on acetic acid-induced colitis in male Wistar rats. Ulcerative colitis (UC) was induced in rats by acetic acid intrarectally, and the protective effects of QA in 10, 30, 60, and 100 mg/kg doses were investigated. Rats were treated for 5 days and their colon tissues were dissected out at the end. Macroscopic and histopathological examinations were performed in colon tissues. Also, the expression of inflammatory and apoptotic genes, including TLR4, IL-1β, INOS, IL-6, TNF-α, NF-κB, Caspase-3, Caspase-8, Bax, and Bcl-2, was measured. Biochemistry indices, such as malondialdehyde (MDA) and nitrite oxide (NO) content, in addition to, total antioxidant capacity (TAC), superoxide dismutase (SOD), catalase (CAT), and enzymes activities were also assessed. Colitis increased the levels of MDA and NO, and enhanced the inflammatory and apoptotic gene expressions, while reducing the SOD and CAT enzymes activity, and TAC levels in the colitis rats. Also, results showed that colitis was associated with the infiltration of inflammatory cells, epithelium damage, and edema in colon tissue. QA significantly ameliorated histopathological indices, oxidative stress, inflammation, and apoptosis in colitis rats. QA ameliorated UC through the inhibition of two TLR4-NF-κB and NF-κB-INOS-NO signaling pathways, which results in the reduction of colitis complications, including oxidative stress, inflammation, apoptosis and histopathological injuries in rats. Therefore it can be concluded, that QA exerts its therapeutic effects through antiapoptotic, antioxidant, and anti-inflammatory properties.

Investigation of the Effects of Opioids on Microglial Nitrite and Nitric Oxide Synthase (iNOS) Production and Phagocytosis during Inflammation.

This study aimed to investigate how opioids affect phagocytosis and microglial nitrite and nitric oxide synthase (iNOS) production during inflammation. Opioids are a group of chemicals that are naturally found in the opium poppy plant and exert a variety of effects on the brain, including pain alleviation in some cases. They are commonly used in surgery and perioperative analgesia. However, research on the impact of opioids on microglial inflammatory factor production and phagocytosis is limited. This study was designed to investigate the effects of opioids on inducible nitric oxide synthase (iNOS) activity and nitric oxide (NO) generation. Moreover, the influence of opioids on the engulfment of C8-B4 microglial cells after stimulation with LPS was also examined. C8-B4 mouse microglial cells were exposed to various concentrations of opioids after stimulation with lipopolysaccharide (LPS) and interferon-γ (IFN-γ). Nitrite production was assayed. The iNOS and Cox-2 were determined by Western blotting, and fluorescent immunostaining was performed to assess the percentage of microglia that engulfed fluorescent microspheres in total microglia cultivating with opioids after being activated by LPS. After LPS and IFN-γ stimulation, microglia produced lower amounts of nitric oxide (NO) production with buprenorphine, salvinorin A, and naloxone (P<0.05). When combined with naloxone, no significant differences were found than buprenorphine. It was observed that buprenorphine and salvinorin A could suppress iNOS expression activated by LPS and IFN-γ. Phagocytosis was greatly increased after LPS stimulation, and a significant increase was observed after adding salvinorin A. Buprenorphine and salvinorin A were found to reduce NO production and iNOS induction in microglial cells activated by LPS and IFN-γ. Salvinorin A promoted the phagocytosis of microglia cells treated by LPS.

Microbial Communities and Soil Respiration during Rice Growth in Paddy Fields from Karst and Non-Karst Areas

Soil microorganism and their relationships with soil respiration in paddy systems in karst areas (KA) of southern China is important for understanding the mechanisms of greenhouse gas emission reduction. Soils were collected from the tillage layer (0–20 cm) during the rice growing season from KA and non-karst areas (NKA) (red soils) from the Guilin Karst Experimental Site in China. Community structures and inferred functionalities of bacteria and fungi were analyzed using the high-throughput sequencing techniques, FAPROTAX and FUNGuild. A bacterial–fungal co-occurrence network was constructed and soil respiration was measured using dark box-gas chromatography and built their relationships. The results indicated that soil respiration was significantly lower in KA than in NKA. Principal component analysis indicated that bacterial and fungal community structures significantly differed between KA and NKA. The OTU ratio of fungi to bacteria (F/B) was positively correlated with soil respiration (p = 0.044). Further, the key network microorganisms were OTU69 and OTU1133 and OTU1599 in the KA. Soil respiration negatively correlated with Acidobacteria Gp6, dung saprotroph-endophyte-litter saprotroph-undefined saprotroph, aerobic nitrite oxidizers and nitrifier in KA (p &lt; 0.05). Overall, this study demonstrated that soil respiration was reduced when soil microorganisms shifted from bacterial to fungal dominance during the rice growing season in KA.

Flower-like 3D MoS2 microsphere/2D C3N4 nanosheet composite for highly sensitive electrochemical sensing of nitrite

Nitrite pollution poses a serious threat to human health and the environment. In this study, a reliable and selective electrochemical (EC) sensor was developed for the quantitative determination of nitrite by combining flower-like three-dimensional (3D) MoS2 microspheres with two-dimensional (2D) C3N4 nanosheets. Benefiting from the synergistic effects of MoS2 and C3N4, the 3D MoS2/2D C3N4 nanocomposite displayed numerous active sites, a 3D mesoporous structure, high conductivity and excellent catalytic activity. The 3D MoS2/2D C3N4-modified glassy carbon electrode (GCE) exhibited a superior electrocatalytic activity toward nitrite oxidation, with a wider linear detection range (0.1–1100 μM), a lower detection limit (LOD) (0.065 μM, S/N = 3), outstanding stability, remarkable reproducibility and strong selectivity. Furthermore, the nitrite EC sensor was successfully applied to detect actual food and environmental samples involving sausage, pickled vegetables, river water and tap water, thus demonstrating the potential of the prepared 3D MoS2/2D C3N4/GCE for food analysis and environmental monitoring.

Oxidation and Phenolysis of Peptide/Protein C-Terminal Hydrazides Afford Salicylaldehyde Ester Surrogates for Chemical Protein Synthesis.

With the growing popularity of serine/threonine ligation (STL) and cysteine/penicillamine ligation (CPL) in chemical protein synthesis, facile and general approaches for the preparation of peptide salicylaldehyde (SAL) esters are urgently needed, especially those viable for obtaining expressed protein SAL esters. Herein, we report the access of SAL ester surrogates from peptide hydrazides (obtained either synthetically or recombinantly) via nitrite oxidation and phenolysis by 3-(1,3-dithian-2-yl)-4-hydroxybenzoic acid (SAL(-COOH)PDT). The resulting peptide SAL(-COOH)PDT esters can be activated to afford the reactive peptide SAL(-COOH) esters for subsequent STL/CPL. While being operationally simple for both synthetic peptides and expressed proteins, the current strategy facilitates convergent protein synthesis and combined application of STL with NCL. The generality of the strategy is showcased by the N-terminal ubiquitination of the growth arrest and DNA damage-inducible protein (Gadd45a), the efficient synthesis of ubiquitin-like protein 5 (UBL-5) via a combined N-to-C NCL-STL strategy, and the C-to-N semisynthesis of a myoglobin (Mb) variant.

A sensor based on NiO/Fe2O3 modified GCE electrode for the detection of nitrite

NiO/Fe2O3 modified glass carbon (GCE) electrode was prepared by electrodeposition of NiO nanoparticles on Fe2O3/GCE. The electrochemical characteristics of NiO/Fe2O3/GCE have been examined using cyclic voltammetry. The enhanced electrocatalytic activity of NiO/Fe2O3/GCE modified electrode for nitrite oxidation may be related to the synergistic effect of NiO and Fe2O3 nanoparticles, which may not only modify the electronic structure of the composite materials but also favor the increase of active sites in NiO/Fe2O3 and help to adsorb more active materials. To detect nitrite, the NiO/Fe2O3/GCE modified electrode was employed as an electrochemical sensor. There is a strong linear correlation between concentration and peak current (R = 0.9993) in the 5–500 μM range, and a detection limit of 0.05 μM (S/N = 3) was established. NiO/Fe2O3 sensors have excellent selectivity and stability as well. The sensor performs well analytically in determining nitrite in tap water, indicating that it has the possibility for efficient application in nitrite detection. This simple, low-cost, stable and highly sensitive nitrite electrochemical sensor provides a promising method for the detection of nitrite in practical samples.

Neuroprotective effects of novel pyrrolidine-2-one derivatives on scopolamine-induced cognitive impairment in mice: Behavioral and biochemical analysis

Alzheimer's disease (AD) is a long-term neurodegenerative condition that impairs cognitive abilities. In brain acetylcholine deficit and oxidative stress may be considered the key pathogenic causes for AD, even though the basic etiology is still unknown. The effects of some novel pyrrolidine-2-one derivatives on the learning and memory deficits caused by scopolamine in mice were examined in the current study. The learning and memory parameters were assessed using the morris water maze test, rota rod test the and locomotor activity. A number of biochemical factors were also evaluated, including acetylcholinesterase (AChE), lipid peroxidation (LPO), reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CA), and nitrite oxide (NO) assay. The current study shows that these derivatives were more effective and comparable to donepezil at treating the behavioral and biochemical changes brought on by scopolamine. The observed results showed pyrrolidine-2-one derivatives as a promising candidate for diseases associated with cognitive deficits.

Nitrogen cycle pattern variations during seawater-groundwater-river interactions enhance the nitrogen availability in the coastal earth critical zone

Hydrological interaction in highly vital and productive coastal earth critical zone (CECZ) significantly impacts the nitrogen cycle and availability, which is the essential foundation for agricultural production. The results of isotopes and microbial sequencing showed that nitrogen fixation and nitrite oxidation are enhanced in the palaeo-saltwater intrusion process. The weakening AmoCAB and Hao impedes the normal nitrogen cycling pathway, promoting the input of organic nitrogen, thus increasing nitrogen availability flux. In the river into the sea, nitrogen fixation is enhanced, while nitrite oxidation, denitrification, and DNRA are weakened. The whole intensity of the nitrogen cycle decreases. In addition, the oxidation of NH4-N to NO2-N in this process is inaccessible, which means that the nitrogen cycle flux is substantially reduced. In the river recharge to groundwater, nitrite oxidation, nitrogen fixation, and ammonia oxidation are enhanced. In the submarine groundwater discharge, the whole intensity of the nitrogen cycle gradually weakens and the nitrogen cycle flux greatly reduces. As the final pool of coastal groundwater and surface water, the significant reduction of the nitrogen cycle intensity and the absence of the pathway link allows nitrogen in seawater to flow out of the inorganic nitrogen cycle by the conversion to organic nitrogen, thus the net flux of nitrogen availability trapped in the hydrological systems increases. The hydrological interaction enhances the breadth of nitrogen sources, the diversity of pathways, and the flux of nitrogen in CECZ, thereby promoting more nitrogen being trapped in system and increasing nitrogen availability.

Differential contribution of nitrifying prokaryotes to groundwater nitrification

The ecophysiology of complete ammonia-oxidizing bacteria (CMX) of the genus Nitrospira and their widespread occurrence in groundwater suggests that CMX bacteria have a competitive advantage over ammonia-oxidizing bacteria (AOB) and archaea (AOA) in these environments. However, the specific contribution of their activity to nitrification processes has remained unclear. We aimed to disentangle the contribution of CMX, AOA and AOB to nitrification and to identify the environmental drivers of their niche differentiation at different levels of ammonium and oxygen in oligotrophic carbonate rock aquifers. CMX ammonia monooxygenase sub-unit A (amoA) genes accounted on average for 16 to 75% of the total groundwater amoA genes detected. Nitrification rates were positively correlated to CMX clade A associated phylotypes and AOB affiliated with Nitrosomonas ureae. Short-term incubations amended with the nitrification inhibitors allylthiourea and chlorate suggested that AOB contributed a large fraction to overall ammonia oxidation, while metaproteomics analysis confirmed an active role of CMX in both ammonia and nitrite oxidation. Ecophysiological niche differentiation of CMX clades A and B, AOB and AOA was linked to their requirements for ammonium, oxygen tolerance, and metabolic versatility. Our results demonstrate that despite numerical predominance of CMX, the first step of nitrification in oligotrophic groundwater appears to be primarily governed by AOB. Higher growth yields at lower ammonia turnover rates and energy derived from nitrite oxidation most likely enable CMX to maintain consistently high populations.

Change in Granulation Potential and Microbial Enrichment Characteristics of Sludge Induced by Microplastics

Microplastics (MPs), as a new type of pollutant, are widely detected in sewage treatment plants. Currently, research on MPs in traditional sewage treatment systems has mainly been focused on the pollution level and distribution characteristics, with a lack of studying the impact of MPs on the sludge granulation. In order to explore the effect of MPs on the granulation process, a microplastic exposure test was conducted by adding polyethylene terephthalate microplastics (PET-MPs), which are widespread in the environment. The operating performance of the system, extracellular polymeric substance (EPS) composition, and flora enrichment were analyzed on the sludge granulation. The results showed that the exposure of PET-MPs significantly accelerated the sludge granulation process, whereas the increase in EPS content dominated by PN enhanced the sludge surface hydrophobicity; the granulation rate and EPS secretion were proportional to the exposed particle size. Microplastics and EPS secretions synergistically promoted the formation of granular sludge. However, continuous microplastic exposure led to deterioration of the system decontamination performance and inhibited the degradation process of pollutants, with the most negative effect of nitrite nitrogen accumulation under 250 μm PET-MPs exposure, as high as (5.08±0.24) mg·L-1. The high-throughput sequencing revealed that the microbial community diversity fell in the experimental group. The dominant bacteria at the phylum level were Proteobacteria and Bacteroidota on the sludge granulation. Rhodocyclaceae, Sphingomonadaceae, Flavobacteriaceae, and Rhodanobacteraceae promoted flocculation by increasing EPS secretion. The decrease in Comamonadaceae and Chitinophagaceae weakened the ammonia and nitrite oxidation capacity of the system, whereas the decrease in Rhodobacteraceae, Hyphomonadaceae, and Xanthomonadaceae inhibited the removal of nitrate nitrogen.

Enhanced reduction of nitrate by TDER packed with surface-modified plastic particles electrodes

Based on Iron cathodes, nitrate could be selectively decomposed into other lower-valence nitrogen compounds, including ammonia, nitrogen gas, nitrite and nitric oxide, but the removal efficiencies of nitrate and total nitrogen (TN), are affected significantly by the synergistic effects of anodes, chloride electrolyte and conductive plastic particles electrodes. In this work, the base material Titanium (Ti) metal plates and plastic particles which surfaces were mainly coated with Ru-Sn oxidizing compounds, were applied as plates anodes and conductive particles electrodes in Three Dimensional Electrode Reactors (TDER). The Ti/RuSn plate anodes showed excellent performance on degrading nitrate, more nitrogen gas (83.84%) and less ammonia (15.51%) was produced, less TN and Iron ion (0.02 mg/L) was left in the wastewater, and less amount of chemical sludge (0.20 g/L) was produced. Furthermore, the removal efficiencies of nitrate and TN were further increased by the surface-modified plastic particles, which were cheap, reusable, corrosion-resistance, easy to obtain as manufactured materials and light to be suspended in waters. The degradation of nitrate and its intermediates was enhanced possibly by the continuous synergistic reactions initiated by hydrogen radicals, which was generated on the countless surficial active Ru-Sn sites of Ti/RuSn metal plate anodes and plastic particles electrodes, among residual nitrogen intermediates, most of ammonia was selectively converted to gaseous nitrogen by hypochlorite from chloride ion reaction.

Microplastics perturb nitrogen removal, microbial community and metabolism mechanism in biofilm system

Microplastics (MPs) are a significant component of global pollution and cause widespread concern, particularly in wastewater treatment plants. While understanding the impact of MPs on nutrient removal and potential metabolism in biofilm systems is limited. This work investigated the impact of polystyrene (PS) and polyethylene terephthalate (PET) on the performance of biofilm systems. The results revealed that at concentrations of 100 and 1000 μg/L, both PS and PET had almost no effect on the removal of ammonia nitrogen, phosphorus, and chemical oxygen demand, but reduced the removal of total nitrogen by 7.40–16.6%. PS and PET caused cell and membrane damage, as evidenced by increases in reactive oxygen species and lactate dehydrogenase to 136–355% and 144–207% of the control group. Besides, metagenomic analysis demonstrated both PS and PET changed the microbial structure and caused functional differences. Some important genes in nitrite oxidation (e.g. nxrA), denitrification (e.g. narB, nirABD, norB, and nosZ), and electron production process (e.g. mqo, sdh, and mdh) were restrained, meanwhile, species contribution to nitrogen-conversion genes was altered, therefore disturbing nitrogen-conversion metabolism. This work contributes to evaluating the potential risks of biofilm systems exposed to PS and PET, maintaining high nitrogen removal and system stability.

Mediation of PM2.5-induced cytotoxicity: the role of P2X7 receptor in NR8383 cells

ABSTRACT Ambient fine particulate matter (PM2.5) is a threat to public health. The P2 X 7purinergic receptor (P2X7R) is a modulator that responds to inflammation. Yet the role of P2X7R in the mediation of PM2.5-induced pulmonary cytotoxicity is rarely investigated. In this study, the expression of P2X7R and its effect on cell viability, oxidative damage, apoptosis, mitochondrial dysfunction and underlying mechanism following PM2.5 treatment in rat alveolar macrophages (NR8383) were analyzed. The outcome indicated that PM2.5 exposure significantly increased the expression of P2X7R, while P2X7R antagonist oATP markedly alleviate the production of reactive oxygen species (ROS), Nitrite Oxidation (NO), mitochondrial membrane potential, apoptosis rate, and release of inflammatory cytokines. In contrast, P2X7 agonist BzATP showed opposite effect in PM2.5-treated NR8383 cells. Therefore, these results demonstrated that P2X7R participated in PM2.5-induced pulmonary toxicity, while the blockade of P2X7R is a promising therapeutic approach of treating PM2.5-induced lung diseases.

Anti-inflammatory material basis and mechanism of Artemisia stolonifera based on UPLC-Q-TOF-MS combined with network pharmacology and molecular docking

This study aimed to explore the anti-inflammatory material basis and molecular mechanism of Artemisia stolonifera based on the analysis of the chemical components in different extracted fractions of A. stolonifera and their antioxidant and anti-inflammatory effects in combination with network pharmacology and molecular docking. Thirty-two chemical components were identified from A. stolonifera by ultra-performance liquid chromatography coupled to tandem quadrupole time-of-flight mass spectrometry(UPLC-Q-TOF-MS). Among them, there were 7, 21 and 22 compounds in water, n-butanol and ethyl acetate fractions, respectively. The antio-xidant capacity of different extracted fractions was evaluated by measuring their scavenging ability against 1,1-diphenyl-2-picrylhydrazyl radical 2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl(DPPH) and 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonic acid)(ABTS) free radicals and total antioxidant capacity [ferric reducing antioxidant power(FRAP) assay]. The inflammatory model of RAW264.7 cells was induced by lipopolysaccharide(LPS), and the levels of nitrite oxide(NO), tumor necrosis factor-α(TNF-α), interleukin-6(IL-6) in the supernatant and the mRNA expression of related inflammatory factors in cells were used to evaluate the anti-inflammatory effects. The results revealed that ethyl acetate fraction of A. stolonifera was the optimal antioxidant and anti-inflammatory fraction. By network pharmacology, it was found that flavonoids such as rhamnazin, eupatilin, jaceosidin, luteolin and nepetin could act on key targets such as TNF, serine/threonine protein kinase 1(AKT1), tumor protein p53(TP53), caspase-3(CASP3) and epidermal growth factor receptor(EGFR), and regulate the phosphatidylinositol-3-kinase-protein kinase B(PI3K-AKT) and mitogen-activated protein kinase(MAPK) signaling pathways to exert the anti-inflammatory effects. Molecular docking further indicated excellent binding properties between the above core components and core targets. This study preliminarily clarified the anti-inflammatory material basis and mechanism of ethyl acetate fraction of A. stolonifera, providing a basis for the follow-up clinical application of A. stolonifera and drug development.

Celery Ethanol Extract Prevents Renal Ischemia-Reperfusion Injury via Increasing Nitrite Oxide and Superoxide Dismutase

Background: Acute kidney injury (AKI) is one of the health problems. Kidney ischemia-reperfusion injury (IRI) contributes to pathological conditions of AKI. An imbalance between renal vasoconstriction and vasodilatation mediators was played a role in IRI and its chronic complications. Stress oxidative and inflammation were major pathomechanism of IRI. Administration of celery ethanol extract is one of the efforts to prevent kidney damage caused by IRI. This study aimed to investigate the time effect of celery ethanol extract administration on inhibition of kidney IRI. Methods: Twenty male Sprague Dawley rats with a weight range of 190-210 g were selected for the study. The rats were divided into five groups randomly: sham operation (SO, n=4) group, IRI group (ischemia-reperfusion injury, n=4), IRI+S7 (celery ethanol extract 1000 mg/kg BW 7 days orally+ischemia-reperfusion injury, n=4), IRI+S14 (celery ethanol extract 1000 mg/kg BW 14 days orally+ischemia-reperfusion injury, n=4), IRI+S28 (celery ethanol extract 1000 mg/kg BW 28 days orally+ischemia-reperfusion injury, n=4). Serum samples were collected for creatinine serum, NO, SOD, and TNF-α measurement. mRNA expression of ET-1 and ETAR was quantified using reverse transcriptase-PCR. Result: Serum creatinine, NO, and SOD level in rats with celery ethanol extract 1000 mg/kg BW for 7 and 14 days administration before IRI induction lower than IRI group (p&lt;0.05) and increase in 28 days administration. Meanwhile, the TNF-α level, ET-1, and ETAR gen expression lower than the IRI group but not significantly different (p&gt;0.05). Conclusion: Administration of celery ethanol extract 1000 mg/kg BW for 7 days and 14 days prevents renal ischemia-reperfusion injury via increasing NO and SOD. Administration more than 28 days is not recommended.

Energy-efficient green synthesis of metal-organic frameworks for effective electrochemical nitrite sensing

This paper describes a green method for synthesizing a metal-organic framework (MOF) based on pyrazole-3,5-dicarboxylic acid (H3PDCA) linker and Ni2+ to detect nitrite electrochemically. The synthesis was performed at room temperature using water as a solvent, and physicochemical and electrochemical characterizations confirmed the successful creation of Ni-PDCA. The study findings underline that the Ni-PDCA exhibited excellent electrochemical performance for nitrite oxidation due to the appreciable conductivity and high electroactive surface area offered by polyhedral Ni-PDCA crystals. In addition, the charge transfer mechanism between nitrite and the ligand contributed to the selective detection of nitrite. Under optimum amperometric settings (0.70 V vs. Ag/AgCl), Ni-PDCA-modified screen-printed carbon electrode (SPCE) exhibited a detection limit of 0.052 µM (S/N = 3) with a sensitivity of 240 µA mM−1 cm−2 in a linear range of 0.1 to 1000 µM. Moreover, the sensor provided good selectivity, high stability (> 28 days), and a fast response time (< 5 s). Remarkable repeatability [Relative standard deviation (RSD) = 0.87%, n = 10] and reproducibility [RSD = 0.67%, n = 4] were other advantages of this sensor. Notably, the evaluation of nitrite in tap water samples confirmed that the Ni-PDCA/SPCE has promising prospects in quantitatively detecting nitrite in real samples. Therefore, this study paves the way for a practical, cost-effective, and eco-friendly electrochemical sensing method for nitrite detection.

Adaptations of Potential Nitrogenase Activity and Microbiota with Long-Term Application of Manure Compost to Paddy Soil

Biological nitrogen fixation complements nitrogen from fertilizers in crop plants under natural conditions. It also contributes to the reduction in chemical fertilizer (CF) utilization in cultivated lands, which fits the concept of sustainable agriculture. From this viewpoint, however, it is still unknown in paddy fields how soil bacterial nitrogenase and microbiota are affected by applied materials in the soil. Therefore, in this study, the effects of long-term material applications on potential nitrogenase activity and the microbiota of soil bacteria were investigated. The nitrogenase activity tended to be higher in manure compost (MC)-applied soils than in CF-applied soils in both summer and winter. Soil bacterial alpha diversity increased whereas soil ammonia availability decreased with the MC application. The dynamic response of soil bacterial microbiota was caused by the MC application. The abundance of Nitrospira, a class of ammonia and nitrite oxidation bacteria, was lower and the abundance of alpha-Proteobacteria was higher in the MC-applied soils than in the CF-applied soils. These results suggest that the alpha diversity increase and restricted availability of NH3-N might contribute to the increase in potential nitrogenase activity in the long-term MC-applied soils.