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Electrocatalytic nitrite reduction (eNO2RR) is a promising alternative route to produce ammonia (NH3). Until now, several molecular catalysts have shown capability to homogeneously reduce nitrite to NH3, while taking advantage of added secondary‐sphere functionalities to direct catalytic performance. Yet, realizing such control over heterogeneous electrocatalytic surfaces remains a challenge. Herein, we demonstrate that heterogenization of a Fe‐porphyrin molecular catalyst within a 2D Metal–Organic Framework (MOF), allows efficient eNO2RR to NH3. On top of that, installation of pendant proton relaying moieties proximal to the catalytic site, resulted in significant improvement in catalytic activity and selectivity. Notably, systematic manipulation of NH3 faradaic efficiency (up to 90 %) and partial current (5‐fold increase) was achieved by varying the proton relay‐to‐catalyst molar ratio. Electrochemical and spectroscopic analysis show that the proton relays simultaneously aid in generating and stabilizing of reactive Fe‐bound NO intermediate. Thus, this concept offers new molecular tools to tune heterogeneous electrocatalytic systems. [ABSTRACT FROM AUTHOR]

Significant global concerns about the environment include the removal of various organic dye contaminants and the detection of toxic nitrite (NO2−). Herein, we developed a novel composite that combines an inorganic perovskite-based alkaline earth stannate (CaSnO3) with aurivillius oxide (Bi2WO6). These components were synthesized by combustion and hydrothermal methods, respectively. The composite was designed for the photocatalytic degradation of methylene blue (MB) and electrochemical sensing of nitrite. The prepared composite was systematically characterized using various analytical techniques to verify its elemental composition and morphology and to determine the particle size and band gap. CaSnO3/Bi2WO6 exhibited a remarkable 92.5% degradation of the carcinogenic MB dye under UV light over approximately 180 minutes. Importantly, it was observed that the designed nanocomposite did not exhibit photo-corrosion properties as the degradation of MB occurred even at pH 11. Furthermore, the CaSnO3/Bi2WO6-modified glassy carbon electrode (GCE) demonstrated excellent electrocatalytic activity, with an obtained limit of detection (LOD) of 0.9 μM. In this work, the CaSnO3/Bi2WO6 nanocomposite shows promising potential for efficient photocatalytic dye degradation and electrochemical sensing of nitrite, with the added advantage of avoiding photo-corrosion even under alkaline conditions. [ABSTRACT FROM AUTHOR]

High-pressure structural study of a piezochromic crystal of a rare di-exo-nitrito nickel(II) complex supported by computational analysis is presented. The examined system is not photoswitchable, however, in the 0–6.2 GPa pressure range the crystal undergoes two phase-transitions accompanied by a colour change and the nitrite ligand isomerisation, which is unique. [ABSTRACT FROM AUTHOR]

Ageing is a natural ontogenetic phenomenon that entails a decrease in the adaptive capacity of the organism, as a result of which the body becomes less adaptable to stressful conditions. Nitrate and nitrite enter the body from exogenous sources and from nitrification of ammonia nitrogen by intestinal microorganisms. This review considers the mechanisms of action of l -arginine, a known inducer of nitric oxide (NO) biosynthesis, and nitrates as supplements in the processes of ageing and aggravated stress states, in which mechanisms of individual physiological reactivity play an important role. This approach can be used as an element of individual therapy or prevention of premature ageing processes depending on the different levels of initial reactivity of the functional systems. A search was performed of the PubMed, Scopus, and Google Scholar databases (n = 181 articles) and the author's own research (n = 4) up to May 5, 2023. The review presents analyses of data on targeted treatment of NO generation by supplementation with l -arginine or nitrates, which is a promising means for prevention of hypoxic conditions frequently accompanying pathological processes in an ageing organism. The review clarifies the role of the individual state of physiological reactivity, using the example of individuals with a high predominance of cholinergic regulatory mechanisms who already have a significant reserve of adaptive capacity. In studies of the predominance of adrenergic influences, a poorly trained organism as well as an elderly organism correspond to low resistance, which is an additional factor of damage at increased energy expenditure. Conclusion It is suggested that the role of NO synthesis from supplementation of dietary nitrates and nitrites increases with age rather than from oxygen-dependent biosynthetic reactions from l -arginine supplementation. [ABSTRACT FROM AUTHOR]

The unique bacterial infection microenvironment (IME) usually requires complicated design of nanomaterials to adapt to IME for enhancing antibacterial therapy. Here, an alternative IME adaptative nitrite reductase-mimicking nanozyme is constructed by in situ growth of ultrasmall copper sulfide clusters on the surface of a nanofibrillar lysozyme assembly (NFLA/CuS NHs), which can temporally regulate nitric oxide (NO) gradient concentration to kill bacteria initially and promote tissue regeneration subsequently. Benefiting from a copper nitrite reductase (CuNIR)-inspired structure with CuS cluster as active center and NFLA as skeleton, NFLA/CuS NHs efficiently boost the catalytic reduction of nitrite to NO. The inherent supramolecular fibrillar networks displays excellent bacterial capture capability, facilitating initial high-concentration NO attacks on the bacteria. The subsequent catalytic release of low-concentration NO by NFLA/CuS NHs-mediated nitrite reduction remarkably promotes cell migration and angiogenesis. This work paves the way for dynamically eliminating MDR bacterial infection and promoting tissue regeneration in a simple and smart way through CuNIR-mimicking catalysis. [ABSTRACT FROM AUTHOR]

Nitro compounds are important intermediates in medicine, agrochemicals, dyes and polymers. In recent years, the use of tert-butyl nitrite (t-BuONO) has attracted great attention and research involving it has made promising progress. Currently, there is no review that specifically discusses the use of t-BuONO for the synthesis of nitro compounds via a C–H bond radical strategy. Therefore, this review aims to focus on the recent progress in the use of t-BuONO as a nitration reagent according to the type of reaction substrate, especially to focus on the discussion of the reaction mechanism in representative cascade reactions to provide insights for the development prospects of tert-butyl nitrite. [ABSTRACT FROM AUTHOR]

Environmental remediation evinces sensitive detection and elimination of contaminants from the environment. Recent investigations delineate nanomaterials as potentially useful agents in environment remediation. In this investigation, we have developed multifunctional CdO‐ZnO nanocomposite (NCs) for efficient degradation of organic dyes and sensitive detection of nitrite ions which also exhibits excellent luminescence and antioxidant properties. The CdO‐ZnO NCs were developed through a facile method which improved the yield quantity by decreasing the energy consumption there by reducing the cost. Thus synthesized CdO‐ZnO NCs were characterized through X‐ray diffraction, FT‐IR, SEM, TEM, EDX studies. These studies confirmed the successful formation of CdO‐ZnO composite and the average particle size of the NCs was found to be ~50 nm. Selective reduction of harmful industrial organic dyes from the water bodies is one of the important aspects of water pollution. As prepared CdO‐ZnO NCs degraded the MB dye completely in 30 min under visible light irradiation. The effect of various parameters such as catalytic load, dye concentration and pH on the degradation of dye was assessed and the NCs exhibited maximum degradation efficiency at 25 mg of catalytic load and alkaline pH of 11. The photoluminescence studies reveal that the NCs have inherent excellent luminescence property by exhibiting the emission band at 277 and 282 nm. From electrochemical studies, the CdO‐ZnO NCs proclaimed magnificent nitrite sensing property with the LOD value of 9.8 μM. Additionally, antioxidant studies disclosed that NCs remarkably scavenged the DPPH free radicals with IC50 value of 249 μg/mL. Thus, this study establishes simple method for the development of efficient mixed oxide material CdO‐ZnO for multifunctional properties that could find industrial applications. [ABSTRACT FROM AUTHOR]

An electrochemical nitrite sensor probe is introduced herein using a modified flat glassy carbon electrode (GCE) and SrTiO3 material doped with spherical-shaped gold nanoparticles (Au-NPs) and polypyrrole carbon (PPyC) at a pH of 7.0 in a phosphate buffer solution. The nanocomposites (NCs) containing Au-NPs, PPyC, and SrTiO3 were synthesized by ultrasonication, and their properties were thoroughly characterized through structural, elemental, optical, and morphological analyses with various conventional spectroscopic methods, such as field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller method. The peak currents due to nitrite oxidation were characterized in detail and analyzed using conventional cyclic voltammetry (CV) as well as differential pulse voltammetry (DPV) under ambient conditions. The sensor response increased significantly from 0.15 to 1.5 mM of nitrite ions, and the sensor was fabricated by coating a conducting agent (PEDOT:PSS) on the GCE to obtain the Au-NPs/PPyC/SrTiO3 NCs/PEDOT:PSS/GCE probe. The sensor's sensitivity was determined as 0.5 ^A/^iM-cm2 from the ratio of the slope of the linear detection range by considering the active surface area (0.0316 cm2) of the flat GCE. In addition, the limit of detection was determined as 20.00 ± 1.00 ^M, which was found to be satisfactory. The sensor's stability, pH optimization, and reliability were also evaluated in these analyses. Overall, the sensor results were found to be satisfactory. Real environmental samples were then analyzed to evaluate the sensor's reliability through DPV, and the results showed that the proposed novel electrochemical sensor holds great promise for mitigating water contamination in the real samples with the lab-made Au-NPs/PPyC/SrTiO3 NC. Thus, this study provides valuable insights for improving sensors for broad environmental monitoring applications using the electrochemical approach. [ABSTRACT FROM AUTHOR]

Anaerobic ammonium oxidation (anammox) is a promising and efficient biological nitrogen removal process, which can economically treat wastewater without organic supplement and aeration. However, to date, the insufficient nitrite in wastewater is the foremost problem encountered in anammox process. This restriction hinders full-scale application of anammox worldwide. Nitrite can be provided by innovative processes such as autotrophic denitrification and denitrifying anaerobic methane oxidation (DAMO). Therefore, the synergy between them and anammox is feasible means to solve the bottleneck. This review unravels the advantages and operating strategies of autotrophic denitrification, DAMO and their coupled processes with anammox. Besides, different electron donors such as reductive sulfur, iron, hydrogen, manganese and methane are analyzed in the two processes. The characteristics of microbial populations and their synergies in microbial communities are deciphered, and nitrogen removal contributions through different microbes are also highlighted. Still, nitrogen conversion pathways are clarified in the processes with different electron donors, and metabolic mechanisms of both autotrophic denitrifiers and DAMO microbes are revealed. Finally, the challenges to be focused in autotrophic denitrification and DAMO processes are proposed, and future perspectives on their coupled process with anammox are also put forward. [ABSTRACT FROM AUTHOR]

A new metallohybrid silsesquioxane (S) was synthesized herein from copper and ferricyanide via a cyanide bridge to produce a new electroactive hybrid material (SCuH), which was then characterized by spectroscopic and microscopic techniques and cyclic voltammetry. The voltammetric behavior of SCuH employing a graphite paste electrode indicates a well‐defined redox couple with formal potential Eθ′=0.76±0.01 V. The electrode exhibited high sensitivity to nitrite and was successfully tested for nitrite detection. The linearity of the analytical curve was 2.0×10−4 mol L−1 − 1.0×10−3 mol L−1, with a limit of detection of 2.65×10−5 mol L−1, and sensitivity amperometric value of 57.63 mA/mol L−1. These findings suggest that this material displays exceptional potential for application in electrochemical sensors designed for nitrite detection. [ABSTRACT FROM AUTHOR]

The electrochemical nitrate reduction for green ammonia production is attracting increasing attention, where the catalysts are widely investigated by controlling the compositions or structures to achieve high performance. However, their reconstructions under reduction potentials are inevitable and uncontrollable, leading to uncertain performance, and a confused understanding of the mechanism. In this work, a strategy is proposed by controlling the pre‐catalyst's reconstruction chemistry toward electrochemical nitrate reduction reaction (e‐NO3RR) with superior activity and stability. To demonstrate the idea, a pre‐catalyst is fabricated with α‐Co(OH)2 and Cu(OH)2 (α‐Co(OH)2/Cu(OH)2), which is in situ reconstructed to a tandem catalyst with Cu and β‐Co(OH)2 (Cu/β‐Co(OH)2) under working potential. Cu/β‐Co(OH)2 achieves an optimal Faraday efficiency for ammonia of 97.7% with a yield rate of 3.9 mmol h−1 cm−2 at −0.5 V, outperforming other reported metal‐hydroxide catalysts. The experimental and theoretical results demonstrate that a tandem catalytic mechanism is responsible for the exceptional performance: 1) Cu functions as the donor of nitrite; and 2) β‐Co(OH)2 serves as active sites for generating active hydrogen and reducing nitrogen‐containing groups. This work highlights that the controllable reconstruction toward improved performance can be realized, and provides an insightful understanding of the mechanism, which is helpful for developing active and stable catalysts for various catalytic applications. [ABSTRACT FROM AUTHOR]

Ebselen (EbSe), a therapeutically significant molecule, is shown to exhibit chalcogen bonding interaction with nitrite anion (ONO−). This report suggests that the σ-holes of EbSe are powerful for offering weak but influential interactions towards biologically relevant ONO−, thereby assisting oxidative transformations like N-nitrosation of aromatic amines. [ABSTRACT FROM AUTHOR]

Summary: The study inquired the influences of l‐arginine and l‐lysine on the physicochemical properties (including weight loss rate, water activity, texture, colour, lipid and protein oxidation, residual nitrite content and total volatile basic nitrogen (TVB‐N) content) of low‐sodium and low‐phosphate Cantonese sausage during the 1‐ and 7‐day storage. The results showed that the addition of l‐arginine or l‐lysine reduced the weight loss rate, TBARS content, carbonyl group content and residual nitrite level, slightly decreased water activity, and enhanced L*, a* and b* values. Compared to the control, 0.3% l‐arginine or l‐lysine declined hardness and chewiness, while 0.6% l‐arginine or l‐lysine elevated these two parameters. However, the addition of l‐arginine or l‐lysine also led to an increase in TVB‐N content. Overall, l‐arginine and l‐lysine improved the qualities of low‐sodium and low‐phosphate Cantonese sausage, which might be attractive to meat product manufacturers. [ABSTRACT FROM AUTHOR]

Le terme de méthémoglobinémie (MetHb) désigne l'état d'oxydation de l'ion Fer dit « ferreux » (Fe2+) en Fer dit « ferrique » (Fe3+) au sein de l'hème, molécule de l'hémoglobine (Hb). Cet état est physiologique si son taux reste contrôlé. L'état ferreux de la molécule d'hème se manifeste lors d'une agression oxydative importante. La physiopathologie de la MetHb implique la NADH, la NADPH et les enzymes du cycle du glucose comprenant le cytochrome-b5-reductase. La MetHb est le plus souvent acquise et plus rarement congénitale. Les causes secondaires regroupent les causes médicamenteuses comme les topiques anesthésiques, ou toxiques comme le « poppers » ou les nitrites. Les causes primaires sont liées à des déficits enzymatiques ou à des anomalies constitutionnelles de l'Hb. Une MetHb trop élevée provoque des symptômes d'intensité variable selon son taux et les comorbidités associées. Les signes cliniques sont dominés par la cyanose, reflet de l'hypoxie tissulaire, et peuvent conduire à des troubles métaboliques graves voire au décès. Le diagnostic peut être complexe car les anomalies biologiques peuvent passer inaperçues. Le traitement repose sur le retour à l'état physiologique de la molécule d'hème. Le bleu de méthylène est le principal antidote en cas de MetHb pathologique mais possède des précautions d'emploi particulières. Nous proposons une mise au point concernant la méthémoglobinémie avec le résumé de sa physiopathologie, ses signes cliniques associés, les examens complémentaires utiles et ses principes thérapeutiques. Methemoglobinemia (MetHb) refers to the state of oxidation of the iron ion "ferrous" (Fe2+) to iron "ferric" (Fe3+) within the heme molecule that makes up hemoglobin (Hb). This state is physiological if its level remains controlled. The ferrous state of the heme molecule occurs in the event of significant oxidative stress. The pathophysiology of MetHb involves NADH, NADPH and glucose cycle enzymes such as cytochrome-b5-reductase. MetHb can be acquired or more rarely, congenital. Acquired causes include drug-induced effects such as topical anesthetics, or toxic effects such as nitrites. Primary causes are linked to enzyme deficiencies or constitutional Hb abnormalities. Excessively high MetHb causes symptoms of varying intensity, depending on the level of MetHb and associated comorbidities. Clinical signs are dominated by cyanosis, indicative of tissue hypoxia, which can be complicated by severe metabolic disorders leading to death. Diagnosis can be complex, as the resulting biological abnormalities may go undetected. Treatment is mainly based on identifying the etiology and restoring the heme molecule to its physiological state. Methylene blue is the main antidote in cases of elevated MetHb, but precautions must be taken in its use, and its physico-chemical effects must be understood. We provide an update on methemoglobinemia, summarizing its pathophysiology and clinical presentations, complementary tests and therapeutic principles. [ABSTRACT FROM AUTHOR]

In this study, the results of hydrochemical measurement aboard the RV Kavoshgar Khalij Fars in the Persian Gulf (PG) in September 2018, May, and November 2019 are discussed. Nitrate, nitrite, ammonium, phosphate, and silicate concentrations, salinity, temperature, dissolved oxygen, and pH in the water column of a 1000-km transect in the PG were studied to determine the present status of nutrient regimes of this region. Nitrate, phosphate, and silicate were more concentrated at the bottom layer and showed a maximum just below the thermocline in summer and autumn. Seasonal distribution of nutrient ratios (N:P, N:Si, Si:P) indicates P limitation in autumn, N limitation in spring, P limitation and poor Si in summer throughout the upper layer. The results of this study do not infer eutrophication in the upper layer of the PG waters in autumn and summer. [ABSTRACT FROM AUTHOR]

The electrochemical C‐N coupling process, facilitating the production of organic nitrogen substances (such as urea, methylamine, formamide, and ethylamine) via the simultaneous reduction of carbon dioxide (CO2) and small nitrogen‐based substances, stands at the forefront of advancing carbon neutrality and the artificial nitrogen cycle. This method has garnered substantial interest due to its potential economic and environmental benefits. Although considerable progress has been achieved in this emerging field, it still faces challenges, including slow reactant adsorption, competing side reactions, and complex multi‐step pathways, resulting in low yields and selectivity. Strategically designing and developing low‐cost and exceptionally performant catalysts is crucial for cost‐effective and precise electrochemical C─N bonding. This article offers an in‐depth review of the electrosynthesis of valuable organic nitrogen compounds at ambient conditions from earth‐abundant resources/wastes, such as CO2 and small nitrogenous molecules (nitrogen: N2, nitrite: NO2−, nitrate: NO3−, ammonia: NH3, etc.), via electrochemical C─N bond formation reactions, especially using carbon‐based catalysts. The relevant electrochemical C─N bond formation mechanisms, the design principles of advanced carbon‐based electrocatalysts, and the impact of different electrolyser designs are discussed, along with the present obstacles and upcoming prospects in this dynamic field. [ABSTRACT FROM AUTHOR]

Electrochemically reducing nitrate (NO3−), a common water pollutant, to valuable ammonia (NH3) offers a green, sustainable, and decentralized route for ammonia synthesis. Electrochemical nitrate reduction reaction (NO3−RR) involves two crucial reaction steps: nitrate deoxygenation followed by nitrite hydrogenation; in particular, the nitrite hydrogenation reaction is the rate‐determining step (RDS) for NO3−RR. In this work, an atomically dispersed cobalt‐phosphorus (Co─P) catalytic pair (CP) with strong electronic coupling is reported. The Co site in Co─P CP effectively activates NO3−, while the P site in Co─P CP facilitates water dissociation to release H+, synergistically enhancing the thermodynamic and kinetic performance of electrochemical nitrate reduction to ammonia. [ABSTRACT FROM AUTHOR]

A functionalization of benzylic C(sp3)–H bonds was established through a mild metal-free intramolecular lactonization protocol in the presence of DDQ/ tert -butyl nitrite as photocatalysts, allowing practical and low-cost access to a series of phthalide products in moderate to excellent yields. Compared with many existing methodologies, this visible-light-driven process exhibits an excellent substrate scope and fascinating features, including the formation of water as the sole byproduct, an abundant and green energy source, commercially available catalysts, and room-temperature reaction. Finally, detailed mechanistic investigations clearly revealed the role of the photocatalysts and molecular oxygen. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal "Chemical Communications" published in 2024. It includes various articles and communications on topics such as heterogeneous catalytic activity, 3D printing of soft active materials, synthesis of substituted a-carbolines, and the structure of caffeine-pyrogallol complex. The journal is published by The Royal Society of Chemistry, a leading chemistry community. The document also mentions approved training courses offered by the society. [Extracted from the article]

Oxidative cyclization of 4-penten-1-ols using a Pd catalyst and n-BuONO or n-BuONO/p-benzoquinone afforded 3-hydroxy- and 3-methoxytetrahydropyrans via terminal selective nucleophilic attack. The radicals formed from n-BuONO and O2 operate as critical oxidants and ligands for Pd. [ABSTRACT FROM AUTHOR]

Transition‐metal carbides with metallic properties have been extensively used as electrocatalysts due to their excellent conductivity and unique electronic structures. Herein, NbC nanoparticles decorated carbon nanofibers (NbC@CNFs) are proposed as an efficient and robust catalyst for electrochemical synthesis of ammonia from nitrate/nitrite reduction, which achieves a high Faradaic efficiency (FE) of 94.4 % and a large ammonia yield of 30.9 mg h−1 mg−1cat.. In situ electrochemical tests reveal the nitrite reduction at the catalyst surface follows the *NO pathway and theoretical calculations reveal the formation of NbC@CNFs heterostructure significantly broadens density of states nearby the Fermi energy. Finite element simulations unveil that the current and electric field converge on the NbC nanoparticles along the fiber, suggesting the dispersed carbides are highly active for nitrite reduction. [ABSTRACT FROM AUTHOR]

Optical detection is an indispensable part of microfluidic systems for nutrient determination in seawater. Coupling total internal reflection capillaries with microfluidic chips is a practical alternative to increase the optical path length for high-sensitivity and a low detection limit in colorimetric assays, which has not been applied in microfluidic devices for seawater nutrients. Here, we present an online microfluidic system which integrated a total internal reflection capillary made of Teflon AF 2400 for the high-sensitivity detection of nitrite and nitrate in seawater. The off-chip capillary lengthens the optical path without changing the internal flow path of the microfluidic chip, enhancing the sensitivity, reducing the detection limit and widening the dynamic range of the system, which significantly improves the performance of the microfluidic system based on wet-chemistry. The detection limit for nitrite is 0.0150 μM using an external 20 cm capillary and 0.0936 μM using an internal 5 cm absorption cell, providing an over 6-fold improvement. Laboratory analysis of surface seawater samples collected from the South China Sea with this system and a one-month online deployment of an autonomous analyzer developed based on this system at a station revealed correlations between the nitrite and nitrate with tide, salinity and chlorophyll over slight variations and narrow ranges, demonstrating the high-sensitivity of this method. [ABSTRACT FROM AUTHOR]

The hydrogen evolution and nitrite reduction reactions are key to producing green hydrogen and ammonia. Antenna–reactor nanoparticles hold promise to improve the performances of these transformations under visible‐light excitation, by combining plasmonic and catalytic materials. However, current materials involve compromising either on the catalytic activity or the plasmonic enhancement and also lack control of reaction selectivity. Here, we demonstrate that ultralow loadings and non‐uniform surface segregation of the catalytic component optimize catalytic activity and selectivity under visible‐light irradiation. Taking Pt−Au as an example we find that fine‐tuning the Pt content produces a 6‐fold increase in the hydrogen evolution compared to commercial Pt/C as well as a 6.5‐fold increase in the nitrite reduction and a 2.5‐fold increase in the selectivity for producing ammonia under visible light excitation relative to dark conditions. Density functional theory suggests that the catalytic reactions are accelerated by the intimate contact between nanoscale Pt‐rich and Au‐rich regions at the surface, which facilitates the formation of electron‐rich hot‐carrier puddles associated with the Pt‐based active sites. The results provide exciting opportunities to design new materials with improved photocatalytic performance for sustainable energy applications. [ABSTRACT FROM AUTHOR]

The electrocatalytic nitrate/nitrite reduction reaction (eNOx -RR) to ammonia (NH3) is thermodynamically more favorable than the eye-catching nitrogen (N2) electroreduction. To date, the high eNOx -RR-to-NH3 activity is limited to strong alkaline electrolytes but cannot be achieved in economic and sustainable neutral/near-neutral electrolytes. Here, we construct a copper (Cu) catalyst encapsulated inside the hydrophilic hierarchical nitrogen-doped carbon nanocages (Cu@hNCNC). During eNOx -RR, the hNCNC shell hinders the diffusion of generated OH- ions outward, thus creating a self-enhanced local high pH environment around the inside Cu nanoparticles. Consequently, the Cu@hNCNC catalyst exhibits an excellent eNOx -RR-to-NH3 activity in the neutral electrolyte, equivalent to the Cu catalyst immobilized on the outer surface of hNCNC (Cu/hNCNC) in strong alkaline electrolyte, with much better stability for the former. The optimal NH3 yield rate reaches 4.0 moles per hour per gram with a high Faradaic efficiency of 99.7%. The strong-alkalinity-free advantage facilitates the practicability of Cu@hNCNC catalyst as demonstrated in a coupled plasma-driven N2 oxidization with eNOx -RR-to-NH3. [ABSTRACT FROM AUTHOR]

The present study details a more environmentally friendly method for synthesizing iron oxide nanoparticles (Fe3O4‐NPs) utilizing Hibiscus sabdariffa (H. sabdariffa) leaf extract. The produced H. sabdariffa/Fe3O4‐NPs underwent characterization through VSM, XRD, FESEM‐EDX, TEM and FTIR analyses. The FESEM and TEM images revealed that the H. sabdariffa/Fe3O4‐NPs had a narrow distribution and an average particle size of 5±2 nm. Catalytic degradation studies of the synthesized Fe3O4‐NPs exhibited efficient reduction of methyl orange (MO) dye. The degradation of MO catalysed by H. sabdariffa/Fe3O4‐NPs follow the pseudo‐first order kinetics, with a rate constant of 0.0328 s−1 (R2=0.9866). Moreover, in electrochemical sensing studies, the anodic peak current of nitrite (NO2−) for H. sabdariffa/Fe3O4‐NPs/GCE showed a linear relationship with its concentration within the range of 0.5–7.5 mM, achieving a detection limit of 0.29 μM. These findings demonstrate that the modified electrode with Fe3O4‐NPs synthesized using H. sabdariffa leaf extract serve as a novel electrochemical sensor for determining NO2− with high sensitivity and reproducibility. [ABSTRACT FROM AUTHOR]

Laser‐induced graphene (LIG) is a promising technology enabling cost‐effective, scalable, and high surface area 3D‐porous graphene electrodes for electrochemical applications. Nitrate in water bodies is a harmful contaminant to humans and the ecosystems. Its detection by electrochemical sensors is challenging due to the interference from nitrite. Herein, for the first time, a LIG‐based electrochemical sensor modified with electrodeposited silver dendrites (EdAg/LIG) without using surfactants is proposed for the detection of nitrate with tunable selectivity and sensitivity. The modified electrode surface is extensively characterized by spectroscopic and electrochemical methods and the underlying mechanism for the formation of dendrites is substantiated. The developed EdAg dendrites/LIG electrode shows excellent sensing properties for the detection of nitrate at pH 2. The interference with nitrite in acidic media is eliminated by implementing a novel strategy to shift the working pH of the electrode to 7. The achieved sensor properties at both pH values surpass other LIG‐based sensors with limit of detection of 0.46 at pH 2 and 5.53 µm at pH 7. The developed sensor also shows good recovery characteristics in mineral, tap, and groundwater across a wide range of concentrations and also demonstrates good stability under temperature fluctuations and deformations. [ABSTRACT FROM AUTHOR]

Edible Swiftlet Nest (ESN) is a swiftlet's saliva product that contains many beneficial compounds. However, improper washing leaves behind toxic nitrite content. To ensure its absence, sensitive and accurate methods are needed, such as UV-Vis spectrophotometry. However, long analysis time and complicated maintenance, limit its further use. In this research, cyclic voltammetry was developed as an alternative analysis method for nitrite content in ESN. The results show that the LOD and LOQ of this method are 0.658529 ppm and 1.995544 ppm, respectively. Compared to this value, analysis using UV-visible spectrophotometry shows lower LOD and LOQ values, respectively 0.061579 ppm and 0.186602 ppm. [ABSTRACT FROM AUTHOR]

The AFm phase found in hydrated Portland cements refers to a family of calcium aluminate phases. Their layer structure is derived from that of portlandite (calcium hydroxide (Ca(OH)2)), but with one third of the Ca2+ ions replaced by a trivalent ion, nominally Al3+ or Fe3+. The resulting charge imbalance gives the layers a positive charge, which is compensated by intercalated anions; the remaining interlayer space is filled with water (H2O). Hydrated cements will contain mixtures of AFm phases and their solid solutions. Portland cement is often modified by addition of soluble nitrate or nitrite salts to protect embedded steel or to shorten the setting time. These nitrate and nitrite ions are capable of entering and occupying AFm anion sites, hence impacting overall phase balances between cement hydrates. In this study AFm phases and solid solution formations were investigated between AFm phases containing SO42−, CO32−, OH−, Cl− and NO2− NO3− ions. Samples were synthesised and subsequently characterised using X-ray diffraction and through the measurement of aqueous solution compositions after 180 days of equilibration in water. [ABSTRACT FROM AUTHOR]

In the realm of electrochemical nitrite detection, the potent oxidizing nature of nitrite typically necessitates operation at high detection potentials. However, this study introduces a novel approach to address this challenge by developing a highly sensitive electrochemical sensor with a low reduction detection potential. Specifically, a copper metal nanosheet/carbon paper sensitive electrode (Cu/CP) was fabricated using a one-step electrodeposition method, leveraging the catalytic reduction properties of copper's high occupancy d-orbital. The Cu/CP sensor exhibited remarkable performance in nitrite detection, featuring a low detection potential of −0.05 V vs. Hg/HgO, a wide linear range of 10~1000 μM, an impressive detection limit of 0.079 μM (S/N = 3), and a high sensitivity of 2140 μA mM−1cm−2. These findings underscore the efficacy of electrochemical nitrite detection through catalytic reduction as a means to reduce the operational voltage of the sensor. By showcasing the successful implementation of this strategy, this work sets a valuable precedent for the advancement of electrochemical low-potential nitrite detection methodologies. [ABSTRACT FROM AUTHOR]

OBJECTIVES: Urinary tract infections (UTIs) are common, but overdiagnosed, in children with spina bifida. We sought to evaluate the diagnostic test characteristics of urinalysis (UA) findings for symptomatic UTI in children with spina bifida. METHODS: Retrospective cross-sectional study using data from 2 centers from January 1, 2016, to December 31, 2021. Children with myelomeningocele aged <19 years who had paired UA (and microscopy, when available) and urine culture were included. The primary outcome was symptomatic UTI. We used generalized estimating equations to control for multiple encounters per child and calculated area under the receiver operating characteristics curve, sensitivity, and specificity for positive nitrites, pyuria ($10 white blood cells/high-powered field), and leukocyte esterase (more than trace) for a symptomatic UTI. RESULTS: We included 974 encounters from 319 unique children, of which 120 (12.3%) met our criteria for UTI. Pyuria had the highest sensitivity while nitrites were the most specific. Comparatively, nitrites were the least sensitive and pyuria was the least specific. When the cohort was limited to children with symptoms of a UTI, pyuria remained the most sensitive parameter, whereas nitrites remained the least sensitive. Nitrites continued to be the most specific, whereas pyuria was the least specific. Among all encounters, the overall area under the receiver operating characteristics curve for all components of the UA was lower in children who use clean intermittent catheterizations compared with all others. CONCLUSIONS: Individual UA findings have moderate sensitivity (leukocyte esterase or pyuria) or specificity (nitrites) but overall poor diagnostic accuracy for symptomatic UTIs in children with spina bifida. [ABSTRACT FROM AUTHOR]

[Display omitted] Electrochemical nitrate reduction reaction (NO 3 RR) has been regarded as a promising alternative to the Haber-Bosch process for sustainable and clean NH 3 production. To develop highly active and stable electrocatalysts for NO 3 – to NH 3 production, Cu-based materials have been considered as potential candidates owing to the excellent NO 3 – adsorption to easily overcome the rate determining step of nitrate to nitrite conversion in NO 3 RR, although the poor NH 3 yield rate is still challenging. In this study, we report a hybrid electrocatalyst with Bi dopant substitutionally incorporated on cuboctahedra Cu 2 O platform (Bi/Cu 2 O) via in-situ hydrothermal method. The Bi/Cu 2 O shows the NH 3 yield rate of 2562.56 μg h−1 mg cat -1 and Faradaic efficiency of 99.2 % at −0.8 V versus reversible hydrogen electrode in a neutral electrolyte, which is the highest performance among previously reported Cu-based electrocatalyst for NO 3 RR to NH 3. The interfacial synergetic effect of sufficient protonation from Bi-doped overlayer and efficient NO 3 – adsorption from the Cu 2 O platform results in excellent NO 3 RR performance. The experimental variable investigations with in-situ attenuated total reflectance-Fourier transform infrared measurement elucidate that not only nitrate to nitrite conversion but also the protonation of *NO 2 is the rate limiting step for NH 3 production. [ABSTRACT FROM AUTHOR]

Aim. To characterize the features of iNOS expression in neurons of the basal magnocellular nucleus against the background of nitrosative stress during experimental colchicine-induced neurodegeneration. Materials and methods. The study was conducted on 30 male Wistar rats. At the first stage of the experiment, cognitive impairments were modeled in rats (n = 10) by intracerebroventricular injection of colchicine, and compared with sham-operated and intact animal groups, the validity of the model was demonstrated using an 8-arm radial maze LE760 (PanLab Harvard Apparatus, Spain). Subsequently, the animals were euthanized with sodium thiopental, and the brain was removed for histological, immunofluorescence, and biochemical analyses. Results. It was found that intracerebroventricular injection of colchicine compared to intact and sham-operated animals leads to disruption of histoarchitecture in the basal magnocellular nucleus of rats with a significant decrease in the Nissl substance area in neurons by 47.3 % and 35.9 %, respectively. At the same time, the level of nitrites in the brain homogenates of animals with experimental neurodegeneration exceeded the comparison groups almost 10 times (intact) and 7 times (sham-operated rats). Meanwhile, immunofluorescence investigation of iNOS expression in the basal magnocellular nucleus of rats with intracerebroventricular colchicine administration, compared to intact and sham-operated animals, revealed a significantly higher value of corrected total cell fluorescence by 22.7 % and 45.3 %, respectively. Simultaneously, it was established that experimental colchicine-induced neurodegeneration is accompanied by a significantly greater number of iNOS+ cells in the basal magnocellular nucleus compared to control groups. Conclusions. Intracerebroventricular injection of colchicine to experimental rats is accompanied by morphological signs of neurodestruction in the basal magnocellular nucleus against the background of nitrosative stress. iNOS expression in rats after intracerebroventricular colchicine administration in the cells of the basal magnocellular nucleus is characterized by a higher enzyme content compared to intact and sham-operated animals. The area of immunopositive cells between experimental groups does not change statistically. Intracerebroventricular administration of colchicine to experimental rats is accompanied by an increase in the number of immunopositive cells for iNOS in the basal magnocellular nucleus.

For the first time, the new approach was utilized to synthesize a novel Zn 3 (OH) 2 V 2 O 7 2H 2 O/Betalains (ZV/Bn) nanocomposite (NCs) through the mediation of natural dye betalains (Bn) extract and a hydrothermal method. With decreased crystallite size (38 nm) and a lower band gap, ZV/Bn NCs are showing a potential candidate with better performances in photoluminescence, nitrite sensing, and corrosion inhibition studies when compared to pure ZV nanoparticles. The optical band gap of ZV/Bn is 2.7 eV, and the Bn is effective in reducing the band gap of ZV by 0.3 eV. ZV/Bn has shown its intense fluorescence properties by emitting a vibrant green emission with a strong emission peak at 535 nm and a subtle peak at 489 nm. The exceptional ability of ZV/Bn fluorescent was significantly employed for the development of latent fingerprint detection, resulting in the high quality of fingerprint images. ZV/Bn-based sensors have proved to be successful due to their low cost, biocompatibility, and high sensitivity towards the detection of the most important bioanalyte, nitrite. The limit of detection (LOD) and the sensitivity of ZV/Bn-based sensor for the detection of nitrite are 17 μM and 7.8E−6 A/M, respectively. Additionally, it shows potential as a corrosion inhibitor. Hence, ZV/Bn NCs emerge as a versatile candidate for optical and electrochemical applications. [ABSTRACT FROM AUTHOR]

Drug use in gay men (GM) in Mexico has been explored mainly from an epidemiological perspective with little research on the impact on well-being, particularly due to consumption dynamics and the sociocultural elements that may intervene in the process. Objective: To analyze drug use and its implications for the well-being of gay men in Mexico. Methods: Three focus groups were held in May 2022 with 19 middle-class gay men from Mexico's northern, central, and southern regions through the Zoom videoconference platform. With the information collected, a content analysis was carried out investigating the following categories: types of substances consumed, frequency, causes, changes in the form of consumption, and effects on well-being. Results: The participants reported low consumption of tobacco or alcohol compared to that of other substances such as inhaled nitrites (poppers), crystal methamphetamine, ecstasy, marijuana, and cocaine. Four environments were identified based on the journey and changes in consumption patterns: the environment of initiation drugs, that of recreational drugs, that of drugs for sexual practices, and that of drugs for greater sexual pleasure. Four aspects related to the motivations for drug use were identified: the family context on drugs, homophobia, HIV diagnosis, and the COVID-19 pandemic. Finally, three main effects on well-being linked to the use of drugs for sexual practices, particularly crystal methamphetamine, are reported: security and violence, social relationships, and health. The findings are discussed within the context of the Set and Setting and Minority Stress theoretical frameworks. Conclusions: Drug use in this population needs to be approached from a multidimensional perspective, considering the sociocultural specificities determining how it is carried out. [ABSTRACT FROM AUTHOR]

In this study, porous polymers with nitrogen heterocyclic core structures are synthesized through the condensation of enaminonitrile and terephthalaldehyde monomers. These polymers are used as a platform to store bioactive nitric oxide (NO) and control its release. NO loading is achieved by nitrosating the polymers with acidified nitrite, a process that also imparts photoresponsivity to the polymers. Polymer composition and porosity affect NO storage and release. It is observed that under UV light at 365 nm in a PBS solution, the polymers (NO@DHP‐POP) can release NO in a manner fully controlled by UV lighting. Under experimental conditions, these porous polymers release NO at a rate of ≈10.0–50.0 µmol g−1 over 60 min. These findings demonstrate the potential of these polymers for integrating NO delivery into phototherapy applications. [ABSTRACT FROM AUTHOR]

Haloarchaea are extremophilic microorganisms belonging to the Archaea domain that require high salt concentrations to be alive, thus inhabiting ecosystems like salty ponds, salty marshes, or extremely salty lagoons. They are more abundantly and widely distributed worldwide than initially expected. Most of them are grouped into two families: Halobacteriaceae and Haloferacaceae. The extreme conditions under which haloarchaea survive contribute to their metabolic and molecular adaptations, thus making them good candidates for the design of bioremediation strategies to treat brines, salty water, and saline soils contaminated with toxic compounds such as nitrate, nitrite, oxychlorates such as perchlorate and chlorate, heavy metals, hydrocarbons, and aromatic compounds. New advances in understanding haloarchaea physiology, metabolism, biochemistry, and molecular biology suggest that biochemical pathways related to nitrogen and carbon, metals, hydrocarbons, or aromatic compounds can be used for bioremediation proposals. This review analyses the novelty of the most recent results showing the capability of some haloarchaeal species to assimilate, modify, or degrade toxic compounds for most living beings. Several examples of the role of these microorganisms in the treatment of polluted brine or salty soils are also discussed in connection with circular economy-based processes. Key points: • Haloarchaea are extremophilic microorganisms showing genuine metabolism • Haloarchaea can metabolise compounds that are highly toxic to most living beings • These metabolic capabilities are useful for designing soil and water bioremediation strategies [ABSTRACT FROM AUTHOR]

Longan shells were treated with or without phosphoric acid activation in different pyrolysis processes, to obtain four biochar materials including direct pyrolysis‐longan shell biochar (D‐LSB), stage pyrolysis‐longan shell biochar (S‐LSB), phosphoric acid activation with direct pyrolysis‐longan shell biochar (PD‐LSB), and phosphoric acid activation with stage pyrolysis‐longan shell biochar (PS‐LSB). This study is to screen out the LSB with the best electrochemical property, being applied in the fabrication of nitrite sensing electrode. A series of structural and electrochemical characterizations revealed that PD‐LSB featured hierarchically porous structures, the largest specific surface area and pore volume as well as the best conductivity, and was applied to modify the glassy carbon electrode (GCE) after mixed with chitosan, to fabricate the electrochemical sensing electrode PD‐LSB/CS/GCE for nitrite detection. The operating condition and performance of the fabricated nitrite sensing electrode were investigated, and the results indicated that it showed the optimal response signal for nitrite detection at pH=3.0, with a linear detection range of 200.0–30000.0 μM and a limit of detection (LOD) of 1.08 μM. The fabricated nitrite sensing electrode also exhibited a good reproducibility, reproducibility and stability as well as good anti‐interference ability, and was applied for the nitrite detection in real aqueous samples successfully. This study provides useful reference information for the preparation of novel biomass materials, and an innovative electrochemical analytical technique for the quick and accurate detection of nitrite in aqueous samples. [ABSTRACT FROM AUTHOR]

Background: Clinical criteria are essential for diagnosing urinary tract infections (UTIs) followed by urine testing, including urinalysis (UA). No study has evaluated the potential related factors that may guide the appropriate collection of urine cultures. Therefore, we aimed to assess the factors that may guide the appropriate collection of urine cultures. Methods: This was a case-control study of patients for whom a urine culture and a UA were ordered in the emergency department (ED) between February 2018 and December 2022. The cases included patients with positive cultures, whereas the controls included patients without growth. Patients were excluded if they were pregnant, underwent any urological procedure, received antibiotics within 3 days before ED presentation, or before culture collection. Results: Of the 263 patients, 123 had growth and 140 did not have growth in urine cultures. In the univariate analysis, female gender, urinary symptoms, urinary white blood cell (WBC) count > 5 cells/hpf, and nitrite in urine were significantly associated with growth (P < 0.05). However, only female gender (aOR, 1.86; 95% CI, 1.06–3.24), urinary WBC count > 5 cells/hpf (aOR, 4.60; 95% CI, 2.21–9.59), and positive nitrite in urine (aOR, 21.90; 95% CI, 2.80–171.00) remained significant in the multivariable analysis. These factors also remained significant in the subgroup of patients with urinary symptoms, except for the female gender. Conclusion: A high urinary WBC count and positive nitrite in UA should be utilized as a guide to collect urine culture, particularly in female patients, to limit the unnecessary ordering of urine culture in the ED. These factors can be used as evidence-based UA reflex criteria as an antimicrobial stewardship intervention. [ABSTRACT FROM AUTHOR]

The controlled synthesis of metal nanomaterials with unconventional phases is of significant importance to develop high‐performance catalysts for various applications. However, it remains challenging to modulate the atomic arrangements of metal nanomaterials, especially the alloy nanostructures that involve different metals with distinct redox potentials. Here we report the general one‐pot synthesis of IrNi, IrRhNi and IrFeNi alloy nanobranches with unconventional hexagonal close‐packed (hcp) phase. Notably, the as‐synthesized hcp IrNi nanobranches demonstrate excellent catalytic performance towards electrochemical nitrite reduction reaction (NO2RR), with superior NH3 Faradaic efficiency and yield rate of 98.2 % and 34.6 mg h−1 mgcat−1 (75.5 mg h−1 mgIr−1) at 0 and −0.1 V (vs reversible hydrogen electrode), respectively. Ex/in situ characterizations and theoretical calculations reveal that the Ir−Ni interactions within hcp IrNi alloy improve electron transfer to benefit both nitrite activation and active hydrogen generation, leading to a stronger reaction trend of NO2RR by greatly reducing energy barriers of rate‐determining step. [ABSTRACT FROM AUTHOR]

AbstractA suitable adsorbent for the treatment of nitrite in wastewater was investigated using a macroporous styrene divinylbenzene strong base polymer for 10−3 M to 6 x 10−3M NaNO2 at room temperature using a batch protocol. The supernatant concentrations were determined rapidly and inexpensively by an electrochemical method. To investigate the sorption mechanism and the rate-determining step, four kinetic models were investigated. The pseudo-second order kinetic model best fit the nitrite adsorption onto the polymer. The highest correlation coefficient (0.9999) and chi square (7.59 x 10−4) values were obtained for 0.046 to 0.276 g L−1 NO2- which is characteristic of chemosorption. The results demonstrate that the investigated polymer is suitable at room temperature for removing nitrites for water to the legally allowed values for 10−3 M to 1.5 x 10−3 M NaNO2 but dilution is required for higher concentrations. [ABSTRACT FROM AUTHOR]

This study focused on the start-up and operating characteristics of the endogenous partial denitrification (EPD) process with different carbon sources. Two sequencing batch reactors (SBRs) with sodium acetate (SBR1#) and glucose (SBR2#) as carbon sources were operated under anaerobic/oxic (A/O) and anaerobic/anoxic/oxic (A/A/O) modes successively for 240 d. The results showed that COD removal efficiency reached 85% and effluent COD concentrations were below 35 mg/L in both SBRs. The difference was that faster absorption and transformation of sodium acetate was achieved compared to glucose (COD removal rate (CRR) was 7.54 > 2.22 mgCOD/(L·min) in SBR1# compared to SBR2#). EPD could be started up with sodium acetate and glucose as carbon sources, respectively, and desirable high nitrite accumulations were both obtained at influent NO3−−N (NO3−-Ninf) increased from 20 to 40 mg/L with nitrate-to-nitrite transformation ratio (NTR) and specific NO3−-N deduction rate (rNa) of 88.4~90% and 2.41~2.38 mgN/(gVSS·h), respectively. However, at NO3−-N of 50~60 mg/L, both the NTR and rNa in SBR1# were higher compared to SBR2# (86.5% > 83.9% and 1.58 > 1.20 mgN/(gVSS·h), respectively). Hereafter, when NO3−-N was increased by 70~90 mg/L, lower NTR and rNa were observed in SBR1# than in SBR2# (72% and 78%, 1.16 and 1.32 mgN/(gVSS·h), respectively). Additionally, similar internal carbon transformations were observed to drive EPD for NO2−−N accumulation, especially for higher and faster carbon transformation with sodium acetate as carbon source compared to glucose. However, precise control of anoxic time as the peak point of nitrite (TNi,max) was still the key to achieve high NO2−−N accumulation. [ABSTRACT FROM AUTHOR]

Introduction: The endorsement of circular economy, zero-waste, and sustainable development by the EU and UN has promoted non-thermal technologies in agro-food and health industries. While northern European countries rapidly integrate these technologies, their implementation in Mediterranean food-supply chains remains uncertain. Aims: We evaluated the usefulness of hydrodynamic cavitation (HC) for valorizing orange peel waste in the fresh orange juice supply chain of the Maltese Islands. Method: We assessed: a) the effectiveness of HC in extracting bioactive compounds from orange peels (Citrus sinensis) in water (35°C) and 70% (v/v) ethanol (-10°C) over time, compared to conventional maceration, and b) the potato sprouting-suppression and biosorbent potential of the processed peel for copper, nitrate, and nitrite binding. Results: Prolonged HC-assisted extractions in water (high cavitation numbers), damaged and/or oxidized bioactive compounds, with flavonoids and ascorbic acid being more sensitive, whereas cold ethanolic extractions preserved the compounds involved in radical scavenging. HC-processing adequately modified the peel, enabling its use as a potato suppressant and biosorbent for copper, nitrate, and nitrite. Conclusion: Coupling HC-assisted bioactive compound extractions with using leftover peel for potato-sprouting prevention and as biosorbent for water pollutant removal offers a straightforward approach to promoting circular economic practices and sustainable agriculture in Malta. [ABSTRACT FROM AUTHOR]

Mycobacterium abscessus (Mab) is an opportunistic pathogen afflicting individuals with underlying lung disease such as Cystic Fibrosis (CF) or immunodeficiencies. Current treatment strategies for Mab infections are limited by its inherent antibiotic resistance and limited drug access to Mab in its in vivo niches resulting in poor cure rates of 30-50%. Mab's ability to survive within macrophages, granulomas and the mucus laden airways of the CF lung requires adaptation via transcriptional remodeling to counteract stresses like hypoxia, increased levels of nitrate, nitrite, and reactive nitrogen intermediates. Mycobacterium tuberculosis (Mtb) is known to coordinate hypoxic adaptation via induction of respiratory nitrate assimilation through the nitrate reductase narGHJI. Mab, on the other hand, does not encode a respiratory nitrate reductase. In addition, our recent study of the transcriptional responses of Mab to hypoxia revealed marked down-regulation of a locus containing putative nitrate assimilation genes, including the orphan response regulator nnaR (nitrate/nitrite assimilation regulator). These putative nitrate assimilation genes, narK3 (nitrate/nitrite transporter), nirBD (nitrite reductase), nnaR, and sirB (ferrochelatase) are arranged contiguously while nasN (assimilatory nitrate reductase identified in this work) is encoded in a different locus. Absence of a respiratory nitrate reductase in Mab and down-regulation of nitrogen metabolism genes in hypoxia suggest interplay between hypoxia adaptation and nitrate assimilation are distinct from what was previously documented in Mtb. The mechanisms used by Mab to fine-tune the transcriptional regulation of nitrogen metabolism in the context of stresses e.g. hypoxia, particularly the role of NnaR, remain poorly understood. To evaluate the role of NnaR in nitrate metabolism we constructed a Mab nnaR knockout strain (MabΔnnaR) and complement (MabΔnnaR+C) to investigate transcriptional regulation and phenotypes. qRT-PCR revealed NnaR is necessary for regulating nitrate and nitrite reductases along with a putative nitrate transporter. Loss of NnaR compromised the ability of Mab to assimilate nitrate or nitrite as sole nitrogen sources highlighting its necessity. This work provides the first insights into the role of Mab NnaR setting a foundation for futurework investigating NnaR's contribution to pathogenesis. [ABSTRACT FROM AUTHOR]

Periplasmic nitrate reductase NapA from Campylobacter jejuni (C. jejuni) contains a molybdenum cofactor (Moco) and a 4Fe–4S cluster and catalyzes the reduction of nitrate to nitrite. The reducing equivalent required for the catalysis is transferred from NapC → NapB → NapA. The electron transfer from NapB to NapA occurs through the 4Fe–4S cluster in NapA. C. jejuni NapA has a conserved lysine (K79) between the Mo-cofactor and the 4Fe–4S cluster. K79 forms H-bonding interactions with the 4Fe–4S cluster and connects the latter with the Moco via an H-bonding network. Thus, it is conceivable that K79 could play an important role in the intramolecular electron transfer and the catalytic activity of NapA. In the present study, we show that the mutation of K79 to Ala leads to an almost complete loss of activity, suggesting its role in catalytic activity. The inhibition of C. jejuni NapA by cyanide, thiocyanate, and azide has also been investigated. The inhibition studies indicate that cyanide inhibits NapA in a non-competitive manner, while thiocyanate and azide inhibit NapA in an uncompetitive manner. Neither inhibition mechanism involves direct binding of the inhibitor to the Mo-center. These results have been discussed in the context of the loss of catalytic activity of NapA K79A variant and a possible anion binding site in NapA has been proposed. [ABSTRACT FROM AUTHOR]

Nitrite is one of the most common nitrogenous compounds, which is not only an important indicator of aquaculture water but also widely used as a food additive. Its potential toxicity poses a huge threat to aquatic products and human health. Therefore, it is important to develop a convenient and rapid sensor for the high-efficient onsite detection of nitrite. In this work, a novel electrochemical sensor was developed for the qualitative and quantitative analysis of nitrite. The developed nitrite electrochemical detection system is easily applied in onsite detection. The electrochemical working electrode was constructed based on the combination of Ag-CeO2 and conductive carbon paste (CPE) with excellent electrocatalysis activity and rapid electron transfer ability. By the application of the developed system and under the optimal conditions, the linear range was from 40.0 μM to 500.0 μM, and the detection limit was reduced to 4.3 μM. The recovery was between 92.1% and 108.1%, and the relative standard deviations (RSDs) were 0.49%~9.31%. The sensor exhibited superior reproducibility, high stability sensitivity, and anti-interference ability, confirming its effectiveness for nitrite analysis. Finally, the developed electrochemical sensor was successfully applied to detect nitrite in beverages and aquaculture water samples, indicating that this approach has great potential in onsite food testing and environmental monitoring. [ABSTRACT FROM AUTHOR]

As a high-efficiency electrocatalyst for NH 3 production via NO 2 − reduction, Mo-doped Co 3 O 4 nanoarray exhibits an extremely high Faradaic efficiency of 96.9 % and a corresponding NH 3 yield of up to 651.5 μmol/h cm−2 at −0.5 V. [Display omitted] • Mo-doped Co 3 O 4 nanoarray on titanium mesh is synthesized as an effective catalyst for NO 2 −-to-NH 3 conversion. • Mo-Co 3 O 4 /TM exhibits a high NH 3 Faradaic efficiency of 96.9 % and a related yield of 651.5 μmol h−1 cm−2 with strong stability. • DFT calculations reveal the catalytic mechanism of NO 2 −RR on Mo-Co 3 O 4. • The fabricated Zn-NO 2 − battery achieves a peak power density of 3.6 mW cm−2 and a satisfactory NH 3 yield of 108.4 μmol h−1 cm−2. Electrochemical conversion of nitrite (NO 2 −) contaminant to green ammonia (NH 3) is a promising approach to achieve the nitrogen cycle. The slow kinetics of the complex multi-reaction process remains a serious issue, and there is still a need to design highly effective and selective catalysts. Herein, we report that molybdenum doped cobalt oxide nanoarray on titanium mesh (Mo-Co 3 O 4 /TM) acts as a catalyst to facilitate electroreduction of NO 2 − to NH 3. Such a catalyst delivers an extremely high Faradaic efficiency of 96.9 % and a corresponding NH 3 yield of 651.5 μmol h−1 cm−2 at −0.5 V with strong stability. Density functional theory calculations reveal that the introduction of Mo can induce the redistribution of electrons around Co atoms and further strengthen the adsorption of NO 2 −, which is the key to facilitating the catalytic performance. Furthermore, the assembled battery based on Mo-Co 3 O 4 /TM suggests its practical application value. [ABSTRACT FROM AUTHOR]

Objective: The mechanism of asymmetric dimethylarginine (ADMA) in thrombosis in patients with nonvalvular atrial fibrillation (NVAF) is still unclear. Our aim was to investigate the relationship between ADMA and indicators of prethrombotic state in NVAF patients and to analyze the predictive role of ADMA in NVAF thrombosis. Methods: A total of 192 NVAF patients were continuously selected from January 2023 to October 2023. Plasma ADMA levels were measured by high‐performance liquid chromatography. P‐selectin (P‐sel), von Willebrand factor (vWF), D‐dimer (D‐D), and plasminogen activator inhibitor‐1 (PAI‐1) levels were measured by enzyme‐linked immunosorbent assay (ELISA). Nitric oxide (NO) levels were measured by the nitrate reductase assay for plasma nitrite/nitrate, then the Griess method (Shanghai Hailian Biotechnology Co., Shanghai, China) was used to calculate plasma NO levels. Results: In our study, ADMA levels were significantly elevated and positively correlated with P‐sel, vWF, D‐D, and PAI‐1, whereas NO levels were significantly negatively correlated with these prethrombotic factors in NVAF. Furthermore, multifactorial logistic regression analysis showed that ADMA and LA diameter were independent predictors of high thrombosis risk (CHA2DS2‐VASc ≥2 score) in patients with NVAF. Conclusions: Our findings suggested that ADMA correlated with the prethrombotic state in NVAF and that reduction of ADMA levels in NVAF patients may be a novel therapeutic strategy for thrombosis risk reduction. [ABSTRACT FROM AUTHOR]