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Electrocatalytic NO reduction reaction (NORR) to synthesize ammonia is of great scientific significance and application value to solve both NO removal and ammonia synthesis. However, the catalytic activity and selectivity are suppressed by the inherent linear scaling relations between the adsorption energies of NORR intermediates. In this work, we have systematically investigated the catalytic performance of specific confined M 2 CO 2 (M = Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W) MXenes for electrochemical reduction of nitric oxide to ammonia. Our results show that the bowl-like confined structure in MXenes can effectively catalyze NORR under the optimal reaction pathway of ∗NO→∗NOH→∗N→∗NH→∗NH 2 →∗NH 3. In particular, the NORR on V 2 CO 2 and Cr 2 CO 2 MXenes are thermodynamically spontaneous (U L = 0 V), which are superior to those of most reported NORR electrocatalysts. Then, we highlight that modifying the transition metal elements in MXenes can selectively tune the adsorption energies of ∗NH 2 and ∗NH 3 , thus breaking their linear scaling relations towards the lower overpotential of NORR. Further analysis of the d-band center and work function illuminates that the modulation mechanism originates from the tunable electronic properties and electron transfer ability of M 2 CO 2 MXenes. Furthermore, the specific confined structures can effectively inhibit the formation of H 2 , N 2 , or N 2 O, which confers V 2 CO 2 and Cr 2 CO 2 MXenes with excellent NH 3 selectivity. This work not only pioneers the effect of specific confined structures on the catalytic performance of MXenes, but also provides general design principles for glorious-performance NORR electrocatalysts. [Display omitted] • Selective reduction from NO to NH 3 can be realized on O-vacancy M 2 CO 2 MXene. • O-vacancy M 2 CO 2 MXene possess superior electrocatalytic performance of NORR. • Design principles to break scaling relations in nitric oxide reduction were proposed. • The novel strategy will accelerate the practical applications of MXenes on catalysis. [ABSTRACT FROM AUTHOR]

Ammonia is an important raw material for agricultural production, playing a key role in global food production. However, conventional ammonia synthesis resulted in extensive greenhouse gas emissions and huge energy consumption. Recently, researchers have proposed electrocatalytic reverse artificial nitrogen cycle (eRANC) routes to circumvent these issues, which can be driven by electrocatalysis and sustainable electricity. Here, a theoretical and computational perspective on the challenges and opportunities with the comparison with experimental results: electrochemical reduction of nitrate (eNO3RR) and nitrite (eNO2RR), electrochemical reduction of nitric oxide (eNORR) combined with oxidative nitrogen fixation are presented. By comparison, the N2→NO→NH3 route is proposed as the most promising in case the NO solubility can be solved well in reactor design. Its high efficiency of ammonia production is demonstrated. Instead, the eNO3RR can be another choice because it is non‐toxic and the solid‐liquid interface is usually efficient for electrochemical reactions, while its low selectivity at low overpotentials is an issue. These fundamentals highlight the potential and key factors of eRANC as an efficient and sustainable route for ammonia production. [ABSTRACT FROM AUTHOR]

Electrocatalytic NO reduction reaction offers a sustainable route to achieving environmental protection and NH3 production targets as well. In this work, a class of dealloyed Ti60Cu33Mn7 ribbons with enough nanoparticles for the high-efficient NO reduction reaction to NH3 is fabricated, reaching an excellent Faradaic efficiency of 93.2% at -0.5 V vs reversible hydrogen electrode and a high NH3 synthesis rate of 717.4 μmol·h-1·mgcat.-1 at -0.6 V vs reversible hydrogen electrode. The formed nanoparticles on the surface of the catalyst could facilitate the exposure of active sites and the transportation of various reactive ions and gases. Meanwhile, the Mn content in the TiCuMn ribbons modulates the chemical and physical properties of its surface, such as modifying the electronic structure of the Cu species, optimizing the adsorption energy of N* atoms, decreasing the strength of the NO adsorption, and eliminating the thermodynamic energy barrier, thus improving the NO reduction reaction catalytic performance. Moreover, a Zn-NO battery was fabricated using the catalyst and Zn plates, generating an NH3 yield of 129.1 μmol·h-1·cm-2 while offering a peak power density of 1.45 mW·cm-2. [ABSTRACT FROM AUTHOR]

A small fraction of NO x (<1%) always exists in CO2 feedstock (e.g. exhausted gas), which can significantly reduce the efficiency of CO2 electroreduction by ∼30%. Hence, electrochemical denitrification is the precondition of CO2 electroreduction. The pH effect is a key factor, and can be used to tune the selectivity between N2 and N2O production in electrochemical denitrification. However, there has been much controversy for many years about the origin of pH dependence in electrocatalysis. To this end, we present a new scheme to accurately model the pH dependence of the electrochemical mechanism. An extremely small pH variation from pH 12.7 to pH 14 can be accurately reproduced for N2O production. More importantly, the obviously different pH dependence of N2 production, compared to N2O, can be attributed to a cascade path. In other words, the N2 was produced from the secondary conversion of the as-produced N2O molecule (the major product), instead of the original reactant NO. This is further supported by more than 35 experiments over varying catalysts (Fe, Ni, Pd, Cu, Co, Pt and Ag), partial pressures (20%, 50% and 100%) and potentials (from −0.2 to 0.2 V vs. reversible hydrogen electrode). All in all, the insights herein overturn long-lasting views in the field of NO electroreduction and suggest that rational design should steer away from catalyst engineering toward reactor optimization. [ABSTRACT FROM AUTHOR]

Low‐loaded platinum‐group single‐atom catalysts on CeO2 (M1/CeO2) were synthesized via high‐temperature atom trapping (AT) and tested for the NO+CO reaction under dry and wet conditions. The activity of these catalysts for NO+CO reaction follows the order Rh>Pd≈Ru>Pt>Ir. For Rh, Ru, and Pd single‐atom catalysts, the N2O byproduct is formed but not clearly observed in Ir and Pt cases, which may result from the higher reaction temperature (>200 °C) required for Pt and Ir catalysts. The presence of water can promote the activity of these M1/CeO2 catalysts for the NO+CO reaction. Under wet conditions, significant NH3 formation occurred during the reaction, which is due to the co‐existence of water‐gas‐shift reaction on these catalysts. Compared with Pt, Pd and Ir, the Rh and Ru single‐atom catalysts show higher selectivity to NH3 species, resulting from the hydride species on the surface. Among all tested catalysts, Ru1/CeO2 shows the highest production of ammonia and highest CO conversion due to excellent water‐gas‐shift activity, whereas Pd1/CeO2 shows lowest ammonia production. Rh1/CeO2 shows the best low temperature NO reduction activity among all tested catalysts. [ABSTRACT FROM AUTHOR]

This Review presents the electrochemical "waste-to-valuables" concept by discussing its practicability in terms of the waste removal efficiency, valuable production efficiency, downstream valuable recovery, applications, and economic appraisal. Specifically, the electrocatalytic upgrading of nitrogenous wastes, i.e., NO and NO 3 − as representative air and aqueous pollutants, respectively, into high-value-added chemicals, i.e., NH 3 via NO/NO 3 − reduction and urea/amide/amine via N-integrated CO 2 reduction is focused. [Display omitted] • The electrochemical upgrading of nitrogenous wastes into value-added products represents a sustainable approach for achieving "waste-to-valuables" conversion. • Design strategies for catalyst, electrolyte, and reactor have been developed to facilitate the electrochemical conversion of nitric oxide/nitrate, both at low and high concentrations, into ammonia. • Nitric oxide/nitrite/nitrate-integrated carbon dioxide reduction unlocks organonitrogen compounds via the electrochemical formation of C−Nbond. In response to the ever-increasing global population and the growing demand for energy and food, human activities have exerted a substantial impact on the global nitrogen cycles. In this context, the electrocatalytic upgrading of nitrogenous wastes into high-value chemicals under ambient conditions, ideally powered by renewable electricity, emerges as a promising approach to concurrently manage nitrogen-containing wastes and facilitate sustainable production of valuable chemicals. This review presents the electrochemical "waste-to-valuables" concept by discussing its practicality in terms of waste removal efficiency, valuable production efficiency, downstream recovery of valuables, potential applications, and economic feasibility. Specifically, the electrocatalytic upgrading of nitrogenous wastes, i.e., nitric oxide and nitrate as representative air and aqueous pollutants, respectively, into high-value-added chemicals, i.e., ammonia via nitric oxide/nitrate reduction and urea/amide/amine via nitrogen-integrated carbon dioxide reduction is focused. Targeting nitrogenous waste exhausts/streams with low/high concentrations, reactor design and catalyst design principles are reviewed with representative examples. Finally, the major challenges and opportunities associated with the practical applications of the "waste-to-valuables" concept are discussed. [ABSTRACT FROM AUTHOR]

An electrochemical nitric oxide (NO) reduction reaction (NORR) can not only eliminate the harmful pollutant but also offer a green approach for ammonia synthesis under mild conditions. However, the activities and Faradaic efficiencies of present electrocatalysts are still not suitable for commercial applications and the mechanism has been rarely studied in detail. Here, by means of first-principles calculations and microkinetic modeling, the potentials of a series of metal-dimer anchored on the PC 6 monolayer (M 2 /PC 6 BAC) as efficient NORR electrocatalysts were examined. Thirteen possible pathways are taken into consideration for the NORR process and a comprehensive reaction network is first constructed. Consequently, the Cr 2 /PC 6 , Mn 2 /PC 6 , Fe 2 /PC 6 and Re 2 /PC 6 BACs are screened out as promising candidates for NORR catalysis. Particularly, the Fe 2 /PC 6 BAC exhibits the best performance among the studied BACs and its NORR rate constant (2.73 × 107 s−1) at 298.15 K is several orders of magnitude larger than those of the other BACs. It can be known from the electronic calculations that the nature of the interaction between NO and the metal-dimer is ascribed to the donation-backdonation mechanism. This work not only provides eligible BACs for NH 3 synthesis but also offers an atomic understanding on the NORR process. [Display omitted] • Eight metal-dimer-anchored PC 6 monolayers were screened out as efficient NORR catalysts. • The Cr 2 /PC 6 , Mn 2 /PC 6 , Fe 2 /PC 6 and Re 2 /PC 6 BACs possess excellent high selectivity. • The Fe 2 /PC 6 BAC exhibits the best catalytic performance for NORR. • The AIMD simulations showed that the Fe 2 /PC 6 BAC exhibits good stability. [ABSTRACT FROM AUTHOR]

• Two-dimensional p -block InSe monolayer is proposed as NO 3 RR and NORR catalysts. • The catalyst possesses excellent catalytic performance and inhibits the formation of by-products. • Vacancy effectively regulates the electronic structure and enhances performance. • The activity enhancement stems from the upshift of the p -band center of active sites. Electrochemical nitrate/nitric oxide (NO 3 −/NO) reduction to ammonia (NH 3) is an environmentally friendly and sustainable strategy that mitigates pollutants while synthesizing value-added products NH 3. Despite the prevalence of transition metal-based catalysts, the exploration of inexpensive two-dimensional (2D) p -block materials is needed in NH 3 synthesis. Based on density functional theory calculations, we proposed an InSe monolayer with single Se vacancy as an outstanding catalyst for NO 3 RR and NORR. The catalyst exhibits exceptional catalytic performance, characterized by a low limiting potential comparable to that of most transition metal-based catalysts, and efficaciously suppresses the formation of competitive by-products. Successful adsorption and activation of NO 3 − and NO molecules are achieved, attributed to the charge rearrangement around the vacancy. The electronic structure analysis reveals that the enhancement of activity stems from the upward shift of the p -band center of unsaturated indium atoms. This work heralds a novel avenue for designing pure 2D p -block NH 3 synthesis catalysts and sheds light on a deeper understanding of the catalytic mechanism at the electronic level. [Display omitted] [ABSTRACT FROM AUTHOR]

Mn-based catalysts have exhibited promising performance in low-temperature selective catalytic reduction of NOx with NH3 (NH3-SCR). However, challenges such as H2O- or SO2-induced poisoning to these catalysts still remain. Herein, we report an efficient strategy to prepare the dual single-atom Ce-Ti/MnO2 catalyst via ball-milling and calcination processes to address these issues. Ce-Ti/MnO2 showed better catalytic performance with a higher NO conversion and enhanced H2O- and SO2-resistance at a low-temperature window (100–150 °C) than the MnO2, single-atom Ce/MnO2, and Ti/MnO2 catalysts. The in situ infrared Fourier transform spectroscopy analysis confirmed there is no competitive adsorption between NOx and H2O over the Ce-Ti/MnO2 catalyst. The calculation results showed that the synergistic interaction of the neighboring Ce-Ti dual atoms as sacrificial sites weakens the ability of the active Mn sites for binding SO2 and H2O but enhances their binding to NH3. The insight obtained in this work deepens the understanding of catalysis for NH3-SCR. The synthesis strategy developed in this work is easily scaled up to commercialization and applicable to preparing other MnO2-based single-atom catalysts. [ABSTRACT FROM AUTHOR]

Transition metals have been recognized as excellent and efficient catalysts for the electrochemical nitric oxide reduction reaction (NORR) to value‐added chemicals. In this work, a class of core–shell electrocatalysts that utilize nickel nanoparticles in the core and nitrogen‐doped porous carbon architecture in the shell (Ni@NC) for the efficient electroreduction of NO to ammonia (NH3) is reported. In Ni@NC, the NC prevents the dissolution of Ni nanoparticles and ensures the long‐term stability of the catalyst. The Ni nanoparticles involve in the catalytic reduction of NO to NH3 during electrolysis. As a result, the Ni@NC achieves a faradaic efficiency (FE) of 72.3% at 0.16 VRHE. The full‐cell electrolyzer is constructed by coupling Ni@NC as cathode for NORR and RuO2 as an anode for oxygen evolution reaction (OER), which delivers a stable performance over 20 cycles at 1.5 V. While integrating this setup with a PV‐electrolyzer cell, and it demonstrates an appreciable FE of >50%. Thus, the results exemplify that the core–shell catalyst based electrolyzer is a promising approach for the stable NO to NH3 electroconversion. [ABSTRACT FROM AUTHOR]

Low-temperature electrocatalytic reduction of nitric oxide (NORR) is promising for the low-cost, high-efficiency removal and utilization of nitric oxide (NO), which couples the two crucial industrial processes of denitration and synthetic ammonia. We reported a binary catalyst of Cu/P–TiO 2 for NORR process, which took advantages of the Cu electrocatalysts and porous TiO 2. The increase of surface areas and channels can improve the adsorption of NO molecules. The decoration of the ultrafine Cu nanoparticles on the porous TiO 2 may prevent the agglomeration of ultrafine Cu nanoparticles. The as-prepared Cu/P–TiO 2 electrode exhibits excellent electrocatalytic activity with a Faraday efficiency of 86.49% and NH 3 yield of 3520.80 μg·h−1·mg−1 in 0.1 M K 2 SO 4 at −0.3 V vs. RHE. The mechanism of the NORR reaction process with Cu/P–TiO2 catalysts was also discussed. This research may broaden the application areas of TiO 2 -based materials in the electrocatalysis and provide a new sight in the treatment of NO pollutants. [ABSTRACT FROM AUTHOR]

We use density functional theory to describe a novel way for metal free catalytic reduction of nitric oxide NO utilizing boron doped graphene. The present study is based on the observation that boron doped graphene and O--N=N--O- act as Lewis acid-base pair allowing the graphene surface to act as a catalyst. The process implies electron assisted N=N bond formation prior to N--O dissociation. Two N2 + O2 product channels, one of which favoring N2O formation, are envisaged as outcome of the catalytic process. Besides, we show also that the N2 + O2 formation pathways are contrasted by a side reaction that brings to N3O3 - formation and decomposition into N2O + NO2 -. [ABSTRACT FROM AUTHOR]

The non-thermal plasma (NTP) is a superior proposed method for nitric oxide removal because of operation at atmospheric pressure and ambient temperature. The energy consumption is the main challenge of using this technology. The packed plasma reactor with dielectric materials has been extensively investigated; it has higher energy efficiency. In this study, the energy efficiency and the other effectiveness factors in nitric oxide removal by NTP reactor packed with ceramic and glass beads optimized and modeled using Response Surface Methodology. The findings showed the maximum energy efficiency was 132.69g/J in the optimal conditions of initial concentration, gas flowrate, and duty cycle(voltage) equal to 1050 ppm, 2.5 L/min, and 9%(22KV), respectively in the packed reactor with ceramic beads by 1.7 times than the empty reactor. It is concluded that the use of ceramic beads as a dielectric material in the discharge space significantly increased energy efficiency in the removal of nitric oxide. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Ru dopant changes electronic charge property and enhances the Lewis acidity of CeO 2. • The reaction favors to proceed on the Ru Lewis acid site. • Brønsted acid site suppresses the NH 3 dissociation but enhances the water formation. • The water formation is the rate determining step for the overall reaction. • Enhancement of catalytic performance can be focused on water formation aspect. Abstract Reaction mechanism of the selective catalytic reduction of nitric oxide (NO) by ammonia (NH 3 -SCR of NO) on the Ru-doped CeO 2 (111) surface was investigated using density functional theory calculation corrected by on-site Coulomb interactions (DFT + U) to understand the role of Ru dopant toward the catalytic performance of CeO 2 based catalysts. The NH 3 -SCR of NO mechanisms on Ru-CeO 2 , which consisted of two consecutive NO reduction pathways, were systematically examined. Each NO reduction consists of important elementary steps such as NH 3 adsorption/dissociation and water formation/desorption. The calculated results reveal that the Ru dopant substantially affects on the electronic charge property and enhances the Lewis acidity of the CeO 2 surface. The NH 3 adsorption and dissociation take place at the Lewis acid site of the catalyst. The first NO reduction via the NHNO intermediate is facile when the Ru dopant presents on the catalyst surface. The presence of Brønsted acid on surface catalyst suppresses the NH 3 adsorption and dissociation but helps in promoting the water formation, which is the rate-determining step of overall reaction. Thus, the performance of this catalyst can be further enhanced by improving the water formation aspect. The obtained results deepen the fundamental understanding of the role of the different active sites on the crucial steps during the reaction and are useful for guiding the way to develop catalysts used in this application. [ABSTRACT FROM AUTHOR]

AIM: Carbon tetrachloride (CCl4) is an organic chemical that produces different tissue-damaging effects when ingested or inhaled. Present study aims to determine whether the application of exogenous melatonin, a neurohormone with numerous biological properties, can prevent disturbances in lung tissue antioxidative capacities and arginine metabolism, tissue inflammation and oxidative damage induced by exposure to CCl4 in rats. METHODS: The effects of melatonin on the changes occurring in rat lung tissue after an acute exposure to CCl4 were studied by monitoring alterations in antioxidant capacities, inflammatory parameters, parameters of arginine metabolism, and lipid and protein oxidative damage. RESULTS: The results indicated that melatonin prevents CCl4-induced lung damage by mitigating tissue antioxidant capacity and preventing nitric oxide production through a shift from nitric oxide synthase to arginase. Also, melatonin partially prevented tissue inflammation and molecules' oxidative modifi cation seen after exposure to CCl4. CONCLUSIONS: The protective activity of melatonin can be attributed to its ability to scavenge both free radicals, as well as to its potential to increase tissue antioxidant capacity. The modulation of inflammatory response through both decrease in tissue inflammatory parameters and influence on arginine-nitric oxide metabolism might be an additional mechanism of action. [ABSTRACT FROM AUTHOR]

Glyphosate, an herbicide used worldwide, has emerged as a pollutant. However, its toxic effects are debated by regulatory authorities. Therefore, it is essential to keep the use of such chemicals under continuous observation, and their effects must be re-evaluated. We used zebrafish embryos to evaluate the toxic effects of glyphosate and its mechanisms. We found that glyphosate induced significant toxicity in a time and concentration-dependent manner. We observed an LD 50 of 66.04 ± 4.6 μg/mL after 48 h of exposure. Glyphosate significantly reduced the heartbeat in a time and concentration-dependent manner indicating cardiotoxicity. Selective downregulation of Cacana1C (L-type calcium channel) and ryr2a (Ryanodine receptor) genes along with selective upregulation of hspb11 (heat shock protein) gene was observed upon exposure to glyphosate indicating alterations in the calcium signaling. A reduction in the nitric oxide (NO) generation was also observed in the zebrafish embryos upon exposure to glyphosate. Our results indicate that glyphosate induces significant toxicity including cardiotoxicity in zebrafish embryos in a time and concentration-dependent manner. Further, cardiotoxicity may be due to changes in calcium and NO signaling. • Glyphosate induces significant toxicity in zebrafish embryos. • Glyphosate lowers the heartbeat in zebrafish embryos. • Glyphosate modulates calcium signaling in zebrafish embryos. • Glyphosate reduces nitric oxide generation in zebrafish embryos. [ABSTRACT FROM AUTHOR]

Abstract Manganese slag is a solid waste produced by the steel industry and usually lacks a proper recycling. In this paper, the manganese slag was used to synthesize a catalyst via microwave assistant method and applied in selective catalytic reduction of nitric oxide. As a result, the catalyst exhibited an excellent low-temperature activity. It removed 78.31% of nitric oxide at 100 °C, 44.44% higher than that of a slag-derived catalyst synthesized by ammonia impregnation, and 63.18% higher than that of a commercial catalyst. Even after a hydrothermal treatment, the catalyst still showed a removal of 69.26% at 150 °C. After a detailed characterization, the low-temperature activity was attributed to an increased amount of oxygen vacancies, which were generated during the microwave synthesis. The generated oxygen vacancies provided adsorption sites for chemisorbed oxygens, which then promoted the electron transfer for reduction of nitric oxide. The main result of this work will help to develop a low-cost catalyst and obtain a high-value-added utilization of manganese slag at the same time. Graphical abstract Image 1 Highlights • A catalyst was synthesized directly from manganese slag. • The slag-derived catalyst was effective than a commercial catalyst in SCR. • The excellent activity was attributed to the higher active components. • The active components included Mn3/4+ species and chemisorbed oxygen. [ABSTRACT FROM AUTHOR]

Endothelial dysfunction and reduced nitric oxide (NO) signaling are a key element of the pathophysiology of nonalcoholic steatohepatitis (NASH). Stimulators of soluble guanylate cyclase (sGC) enhance NO signaling; have been shown preclinically to reduce inflammation, fibrosis, and steatosis; and thus have been proposed as potential therapies for NASH and fibrotic liver diseases. Praliciguat, an oral sGC stimulator with extensive distribution to the liver, was used to explore the role of this signaling pathway in NASH. We found that sGC is expressed in hepatic stellate cells and stellatederived myofibroblasts, but not in hepatocytes. Praliciguat acted directly on isolated hepatic stellate cells to inhibit fibrotic and inflammatory signaling potentially through regulation of AMPK and SMAD7. Using in vivo microdialysis, we demonstrated stimulation of the NO-sGC pathway by praliciguat in both healthy and fibrotic livers. In preclinical models of NASH, praliciguat treatment was associated with lower levels of liver fibrosis and lower expression of fibrotic and inflammatory biomarkers. Praliciguat treatment lowered hepatic steatosis and plasma cholesterol levels. The antiinflammatory and antifibrotic effects of praliciguat were recapitulated in human microtissues in vitro. These data provide a plausible cellular basis for the mechanism of action of sGC stimulators and suggest the potential therapeutic utility of praliciguat in the treatment of NASH. [ABSTRACT FROM AUTHOR]

We report, for the first time, the possibility of using N‐doped C60 fullerene (C59N) as a novel and highly active metal‐free catalyst for reduction of NO molecules to N2O. First‐principles density functional theory calculations are used to find the most energetically favorable adsorbed/coadsorbed configurations of NO molecules over C59N. Our results indicate that introducing a N impurity in C60 can induce a positive charge and large spin density over the carbon atoms nearest to the dopant atom. Consequently, these carbon atoms are identified as the most reactive sites to interact with the NO molecule. According to our results, the dissociation of NO molecule over C59N is almost impossible, due to its relatively high activation energy (1.35 eV). The reduction of NO over C59N starts with the coadsorption of two NO molecules to form (NO)2 species, followed by the dissociation of (NO)2 into N2O and an active atomic oxygen (Oads). The energy barrier to convert NO molecules into N2O ranges from 0.33 to 0.75 eV, which indicates this process is likely to proceed at normal temperature. Besides, by overcoming a negligible energy barrier (0.18 eV), the remaining Oads moiety can be easily eliminated by a CO molecule. To further understand the role of nitrogen atoms in the NO reduction process, the catalytic performance of high percentage N‐doped fullerene (C48N12) is also studied. [ABSTRACT FROM AUTHOR]

The second coordination sphere constitutes a distinguishing factor in the active site to modulate enzymatic reactivity. To unravel the origin of NO‐to‐N2O reduction activity of non‐heme diiron enzymes, herein we report a strong second‐coordination‐sphere interaction between a conserved Tyr197 and the key iron–nitrosyl intermediate of Tm FDP (flavo–diiron protein), which leads to decreased reaction barriers towards N–N formation and N–O cleavage in NO reduction. This finding supports the direct coupling of diiron dinitrosyl as the N–N formation mode in our QM/MM modeling, and reconciles the mechanistic controversy of external reduction between FDPs and synthetic biomimetics of the iron–nitrosyls. This work highlights the application of QM/MM 57Fe Mössbauer modeling in elucidating the structural features of not only first, but also second coordination spheres of the key transient species involved in NO/O2 activation by non‐heme diiron enzymes. [ABSTRACT FROM AUTHOR]

Abstract Nitrous oxide (N 2 O) and nitric oxide (NO) emissions from domestic wastewater treatment had been widely investigated due to their severe greenhouse effect and stratospheric ozone depletion. Researches concerning N 2 O and NO emissions from industrial wastewater treatment which usually contain high concentrations of nitrogen and refractory organics were still limited. In this study, N 2 O and NO emissions from a biological aerated filter (BAF) for coking wastewater treatment were investigated that achieved efficient nitrogen and chemical oxygen demand (COD) removal efficiency through short-cut nitrification and denitrification. Notably, emission factor of N 2 O and NO reached 23.58% and 0.09% respectively, much higher than those emitted from most domestic wastewater treatment plants. Moreover, batch experiments revealed that nitrifier denitrification contributed as high as 97.17% and 93.89% of the total generated N 2 O and NO, which was supposed to be the main source of green-house gases (GHGs) during coking wastewater treatment. The inhibition of denitrifying reductase by the toxic components in coking wastewater and the severe nitrite accumulations were key factors promoting the high emission of N 2 O and NO. Microbial community analysis based on high throughput sequencing of 16S rRNA gene revealed that ammonia-oxidizing bacteria and denitrifying bacteria distributed abundantly in the BAF reactor, while nitrite-oxidizing bacteria was almost absent. The huge imbalance between NO and N 2 O reductase was an underlying explanation for the high N 2 O emission in the present coking wastewater treatment according to Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) result. This study is of great significance to understanding the high N 2 O and NO emission and developing the control strategy when treating industrial wastewater with high-strength nitrogen and refractory organics. Graphical abstract Image 1 Highlights • Efficient nitrogen removal from coking wastewater was achieved in BAF. • N 2 O and NO emission factors reached 23.58% and 0.09% in the BAF. • Nitrifier denitrification contributed 97.17% of the total N 2 O generation. • Refractory organics decreased nitrogen removal and promoted N 2 O emission. • Large imbalance between NO and N 2 O reductase was revealed. [ABSTRACT FROM AUTHOR]

Abstract The experimental study was carried out on a constant speed multi-cylinder spark ignition engine fueled with hydrogen. Exhaust gas recirculation (EGR) and water injection techniques were adopted to control combustion anomalies (backfire and knocking) and reduce NOx emission at source level. The experimental tests were conducted on the engine with varied EGR rate (0%–28% by volume) and water to hydrogen ratio (WHR) (0–9.25) at 15 kW load. It was observed from the experiments that both the strategies can control backfire effectively, but water injection can effectively control backfire compared to EGR. The water injection and EGR reduce the probability of backfire occurrence and its propagation due to the increase in the requirement of minimum ignition energy (MIE) of the charge, caused mainly due to charge dilution effect, and reduction in flame speed respectively. The NOx emission was continuously reduced with increase in EGR rate and WHR, but at higher rates (of EGR and WHR), there was an issue of stability of engine operation. It was found from the experimental results that at 25% EGR, there was 57% reduction in NOx emission without drop in brake thermal efficiency whereas, with WHR of 7.5, the NOx emission was reduced by 97% without affecting the efficiency. The salient point emerging from the study is that water injection technique can control backfire with ultra-low (near zero) NOx emission without compromising the performance of the hydrogen fueled spark ignition engine. Highlights • Backfire and knocking can be controlled by EGR and water injection. • Backfire can be more effectively controlled by water injection rather than EGR. • NOx emission was reduced drastically with water injection compared to EGR. • Near zero NOx emission with water injection without affecting the performance. [ABSTRACT FROM AUTHOR]

Abstract The electrochemical reduction of nitric oxide (NO) catalyzed by metal porphyrins as enzyme mimics provides a promising way to understand its roles in biological denitrification. Here, a stepwise electrocatalytic reduction of NO was demonstrated by a cationic picket-fence porphyrin incorporated in an ultrathin phospholipid film. The mass transport-corrected Tafel slopes demonstrated −117 mV/dec and −60 mV/dec for the first and second reduction of NO at physiological pH (pH 7.0), respectively, suggesting a distinguish mechanism for the two-step reduction of NO. More significantly, the potential of the first reduction is constant at −0.37 V vs. NHE while the second potential shifted positively with decreasing pH, giving pH dependence with a slope of −43 mV/pH. A kinetic mechanism of electrocatalytic NO reduction is thus proposed, and provides a promising hint for decoding the functions of the various enzymes. Graphical abstract Unlabelled Image Highlights • Stepwise electrocatalytic reduction of nitric oxide was realized by cationic picket-fence porphyrin. • The kinetic process of NO reduction was investigated by Tafel plots. • The pH dependence was identified for the second reduction of NO. • A detailed mechanism on electrocatalytic reduction of NO is proposed. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The NOx conversion of the MnO x /CePO 4 catalyst was above 80% even at 180 °C. • The MnO x /CePO 4 catalyst exhibits an excellent water tolerance and N 2 selectivity. • The process of NO oxidation to NO 2 over the catalyst plays a key role during the NH 3 -SCR process. • Monodentate nitrates were the major active species for the NO removal. • The reaction process of the MnO x /CePO 4 catalyst was majorly conducted via the Langmuir–Hinshelwood mechanism. Abstract The MO x (M = Cu, Mn, Co)/CePO 4 support was firstly prepared via the hydrothermal and impregnated method. Selective catalytic reduction of NO with NH 3 (NH 3 -SCR) results showed that the MnO x modifications greatly improved the SCR activities at low temperatures. The NOx conversion of the MnO x /CePO 4 catalyst was above 80% even at 180 °C. In-situ DRIFTS results suggest that the SCR reaction is majorly conducted between the absorbed monodentate nitrate and NH 3 species (i.e., the Langmuir–Hinshelwood mechanism). MOx (M = Cu, Mn, Co) exists in the formation of nano-size particles obtained by SEM and TEM directly. These nano-size particles can provide active surface adsorbed oxygen and thus improve the NO oxidation ability as indicated by the O 2 -TPD and NO oxidation tests. The process of NO oxidation to NO 2 plays a key role to produce the absorbed monodentate nitrate as indicated by the In-situ DRIFTS. The support CePO 4 acts as the acid sites to form highly active NH 4 + species. The synergic effect between the MnO x and CePO 4 contributed to the high SCR activity over the MnO x /CePO 4 catalyst. Additionally, the MOx/CePO 4 catalyst exhibits an excellent water tolerance and N 2 selectivity. Consequently, the MnO x /CePO 4 catalyst becomes the potential catalyst for the practical process. [ABSTRACT FROM AUTHOR]

Objectives: Nitric oxide (NO) represents the most powerful endogenous molecule with vasodilator action mainly produced by endothelial nitric oxide synthase (eNOS) enzyme. Polymorphisms and epigenetic-sensitive mechanisms can modulate the expression of eNOS gene, leading to the endothelial dysfunction. This review updates on the mechanistic role of NO in the regulation of platelet activation, as well as the impact of eNOS genetic and epigenetic modifications on arterial thrombosis onset.Design: A systematic search was addressed to examination of PubMed databases with the following terms: nitric oxide; arterial thrombosis; endothelial dysfunction; DNA variations; epigenetic modifications; personalized therapy; network medicine.Results: G894T, -786T/C, and 4b/4a variable number tandem repeat (VNTR), are the main classes of polymorphisms harbored in eNOS gene associated to increased arterial thrombosis risk. DNA methylation, histone/non-histone modifications, and microRNA (miRNAs) can modulate eNOS gene expression. Investigators largely focused on the role of miRNAs in modulating NO production in arterial thrombosis development. In detail, miR-195, and miR-582 are inversely correlated both to eNOS and NO levels, thus suggesting novel biomarkers.Conclusion: We are far from incorporating omics pathogenic data from bench to arterial thrombosis bedside. Network medicine is an emerging paradigm that ideally overcomes the current shortcomings of the reductionist approach. Despite several clinical limitations, the network-based analysis of the interactome might reveal the key nodes underlying the perturbations of the arterial thrombosis, thus advancing personalized therapy. [ABSTRACT FROM AUTHOR]

Abstract In the past two years, a pilot-scale plasma gasification was carried out. With the help of this project, we investigated the possibility to recycle plasma gasification-derived slag as an effective catalyst by adjusting co-treatment ratio between medical waste and fly ash. As a result, when the co-treatment ratio of fly ash increased, the derived slag showed a bigger content of transition metal, together with a higher activity for selective catalytic reduction of nitric oxide. Specifically, the co-treatment slag with a best activity removed 64.4% of nitric oxide (1000 ppm) at 250 °C, 23.5% higher than the slag from single treatment of medical waste. On the other hand, almost all zinc (15.85–16.99 mg/g) and plumbum (0.72–1.16 mg/g) from raw materials were enriched in the secondary fly ash. Hence, if the secondary fly ash was treated by the plasma gasification again, these heavy metals would obtain further enrichments, which transformed the secondary fly ash into a potential resource for metallurgy. The main result of this work indicated a proper co-treatment of hazardous wastes by the plasma gasification produced high-value-added products. The plasma gasification was a "zero discharge" technology for the treatment and recycle of various hazardous wastes. Highlights • Medical waste and fly ash were co-treated by thermal plasma. • The co-treatment regulated the amount of transition metals in slag. • Plasma-derived slags were used in selective catalytic reduction of nitric oxide. • The regulated slag showed better catalytic activity. • Co-treatment produced a more effective catalyst. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Chemotherapy based on nitric oxide (NO)-releasing was described. • Through molecular imprinting with cancer cells achieved targeting NO-releasing. • In vitro and in vivo investigation confirmed the effective chemotherapy. • NO based chemotherapy avoided side effects of traditional chemotherapy. Abstract It is the goal for the development of cancer target chemotherapy with specific recognition, efficient killing the tumor cells and tissues to avoid the intolerable side effects. Molecular imprinted polymer (MIPs) nanoparticles could introduce kinds of specific bio-markers (template molecules) into the nanoparticles with the subsequent removal, leaving special holes in the structure with predictable recognition specificity with cells. Herein, we design and synthesize a kind of sialic acid (SA) over-expressed tumor target hollow double-layer imprinted polymer nanoparticles with S -nitrosothiols for nitric oxide (NO)-releasing as chemotherapy. Equilibrium/selective bindings properties and probe experimental results implies that the MIPs have an intelligently selective binding to cancer cells featuring high levels of SA glyans, providing precondition for the disulfide polymer assisted cell uptake, intracellular GSH induced decomposition and rapid NO-releasing. Cytotoxicity assay with kinds of cells demonstrates the intelligent in vitro SA over-expressed tumor cells targeting recognition, intracellular delivery and cytotoxicity. In vivo bio-distribution in tumor sites and major organs, significant suppression of tumor growth, tumor-bearing mice survival unit, and the systemic toxicity investigation experiments confirm the effective chemotherapy of the S -nitrosothiols MIPs nanoparticles for the target recognition and the controlled NO release for tumor treatment comparing to the results with S -nitrosothiols CPs as delivery system. The inevitable small amount of NO leakage from S -nitrosothiols MIPs would take part in normal physiological activities and not cause serious side effects. For the first time, this kind of nitric oxide based chemotherapy and molecular-imprinting cell recognition technique both in vitro and in vivo , might provide a solution for accurate therapy to various forms of cancer with specific markers and avoid the intolerable side effects of the traditional chemotherapy treatment. [ABSTRACT FROM AUTHOR]

Abstract The purpose of this study is to analyze the possibility of combining two innovative combustion technologies in large-scale pulverized coal fired plants: Moderate or Intense Low Oxygen Dilution (MILD) and oxy-combustion. The combination of both technologies, namely Oxy-MILD combustion, is expected to bring synergetic effects: NO x reduction, CO 2 capture possibility, fuel flexibility and uniformity of heat fluxes and species concentrations. In this work, the predictable advantages of adopting this technology, with respect to conventional boilers, are evaluated by means of CFD modeling, in terms of pollutant emissions and uniformity of heat fluxes. In a previous work, the developed CFD model was validated against available experimental data of MILD combustion in a pilot-scale furnace and it was demonstrated that the proposed model captures the combustion features with good accuracy. In order to identify the effective potential of Oxy-MILD combustion and its possible uses on an industrial scale, an application in the boiler is analyzed in the current work. Results show that the temperature and species concentration distributions reach an acceptable level of uniformity in the boiler; similarly, the wall heat flux profile is uniform along the boiler height, as in the fluidized bed technology. The CO 2 concentration at the boiler exit, for an excess oxygen ratio of 1.1, is about 95.8%; this value is slightly increased for lower excess oxygen ratio, even though in this case, incomplete combustion occurs. Finally, lower NO x (70 mg/MJ) than other technological solutions are obtained owing to the prevention of thermal and prompt NO x , owing to the absence of N 2 in the oxidizer, and to the re-burning mechanism, which is predominant especially when recycled NO x is considered. Highlights • The effective potential of Oxy-MILD combustion and its possible applications on industrial scale are presented. • The temperature and species concentration distributions reached an acceptable level of uniformity. • The wall heat flux profile was uniform along the boiler height comparable with the one of a fluidized bed boiler. • The predicted carbon dioxide concentration at the boiler outlet is about 95.8%. • The NO x are reduced under Oxy-MILD combustion with respect to traditional combustion in air. [ABSTRACT FROM AUTHOR]

Abstract Background The nuclear genome of Chlamydomonas reinhardtii encodes a dozen hemoglobins of the truncated lineage. Four of these, named THB1–4, contain a single ~130-residue globin unit. THB1, which is cytoplasmic and capable of nitric oxide dioxygenation activity, uses a histidine and a lysine as axial ligands to the heme iron. In the present report, we compared THB2, THB3, and THB4 to THB1 to gain structural and functional insights into algal globins. Methods We inspected properties of the globin domains prepared by recombinant means through site-directed mutagenesis, electronic absorption, CD, and NMR spectroscopies, and X-ray crystallography. Results Recombinant THB3, which lacks the proximal histidine but has a distal histidine, binds heme weakly. NMR data demonstrate that the recombinant domains of THB2 and THB4 coordinate the ferrous heme iron with the proximal histidine and a lysine from the distal helix. An X-ray structure of ferric THB4 confirms lysine coordination. THB1, THB2, and THB4 have reduction potentials between −65 and −100 mV, are capable of nitric oxide dioxygenation, are reduced at different rates by the diaphorase domain of C. reinhardtii nitrate reductase, and show different response to peroxide treatment. Conclusions Three single-domain C. reinhardtii hemoglobins use lysine as a distal heme ligand in both Fe(III) and Fe(II) oxidation states. This common feature is likely related to enzymatic activity in the management of reactive oxygen species. General significance Primary structure analysis of hemoglobins has limited power in the prediction of heme ligation. Experimental determination reveals variations in this essential property across the superfamily. Graphical abstract Unlabelled Image Highlights • Lysine heme ligation is common to three hemoglobins from Chlamydomonas reinhardtii. • These globins have potentials near −100 mV and are capable of NO dioxygenation. • A fourth globin, lacking a conserved histidine, is folded but binds heme weakly. • C. reinhardtii is a promising system to relate globin sequence and function. [ABSTRACT FROM AUTHOR]

Abstract: Large‐scale, uniform, monodisperse LaCO3OH cherry‐blossom‐like nanogears and/or nanocubes have been synthesized under hydrothermal reaction conditions. Upon the addition of only 5 mol% Ca2+ ions into a La nitrate salts solution with pH 8.5, LaCO3OH crystals with novel cubic or nanogear structures are formed in the hexagonal phase. The hydrothermal reactions were carried out without the addition of a template or catalysts. Both 24 hour and 48 hour hydrothermal reactions yield 100% pure LaCO3OH with no irregular particles. We examined the photoluminescence properties of the as‐synthesized powders of the pure LaCO3OH nanogears and found one broad emission band centered at 394 nm after excitation at λ  =  280 nm. The NO reduction activity was also examined over highly dispersed CaO‐containing La2O3 obtained after calcination the LaCO3OH at 800○C for 2 hours. The CaO‐containing La2O3 catalysts showed good stability for NO reduction with CH4 in the presence of O2 and H2O vapor. [ABSTRACT FROM AUTHOR]

Abstract The uniformity of NH 3 in the flue gas is the main factor improving the efficiency during the hybrid selective non-catalytic reduction (SNCR)-selective catalytic reduction (SCR) denitrification process. This work presents the optimized ammonia injection grid (AIG) to enhance the mixing performance and optimize concentration uniformity. A testing ammonia injected facility with a scale of 1:1 is established to experimentally simulate the NH 3 mixing behavior in the tail flue gas duct employing the tracer gas. A novel injection grid with multiple inclined nozzles is proposed to replace the conventional direct-injection type. The flow field and tracer gas concentration field are studied under the three conditions with various inclined jet angles including 0°, 30° and 45°. From results, mixing enhancement between jet and crossflow for the inclined injection grid is achieved. It is also indicated that the inclined angle plays an important effect on jet rigidity and tracer gas dilution. The flow field and tracer gas mixing performances are quantitatively analyzed by using the root mean square deviation coefficient. Multiple jets with an inclined angle of 30° achieved the best mixing performance. Consequently, optimized AIG design has shown effective NO x control performance in industrial utility furnace. Highlights • Multiple inclined jets are proposed to replace the conventional direct-injection type. • Improve the velocity and concentration distribution uniformity. • Optimized ammonia injection grid has been applied in industrial utility furnace. • Achieve the requirement of NO x emission concentration lower than 50 mg/Nm3. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A complete catalytic cycle including adsorption of reactants, activation of the hydroxylammonium chloride, formation of hyponitrous acid intermediates ((HNO) 2 ), removal of water molecules to generate N 2 , has been proposed based on our mechanism study. • The key intermediate (HNO) 2 toward N 2 is identified, and the rate–limiting step in the activation of NH 2 OH⋅HCl is a proton transfer process. • Electronic structure analysis indicates that the coordinated NO has the high electrophilic activity because the Ru → NO+ back donating bonding interaction. Abstract Reaction mechanism corresponding to reduction of NO to N 2 by hydroxylammonium chloride (NH 2 OH⋅HCl) catalyzed by a ruthenium–substituted Keggin-type polyoxometalates (POMs) has been studied by using density functional theory (DFT) method with the M06L functional. A complete catalytic cycle including adsorption of reactant, activation of the hydroxylammonium chloride, formation of hyponitrous acid intermediates ((HNO) 2 ), removal of water molecules to generate N 2 , has been proposed based on our mechanism study. The key intermediate (HNO) 2 toward N 2 is identified. The Ru center in this POM complex is proposed to be the active site, responsible not only for the formation of (HNO) 2 by the reaction of NO and NH 2 OH⋅HCl but also for the subsequent two dehydration steps to form N 2 , which is well in agreement with available experimental literature. The calculated whole energy profiles indicate that the formation of dinitrogen is controlled by thermodynamic factor. Detailed electronic structure analysis indicates that the coordinated NO is a good electrophile and responsible for the catalytic activity because the Ru → NO+ back donating bonding interaction. These results provide a valuable insight to development of the redox catalyst of NO into inorganic POM field. [ABSTRACT FROM AUTHOR]

Nitrogen oxide (NO x ) is one of the world’s major air pollutants. Thus, utilizing inexpensive mineral materials to develop an efficient and low-temperature denitrification catalyst is of great significance. In the present work, palygorskite (Pal)-supported perovskite-type LaFe 1-x Ni x O 3 (x = 0.1–0.9) nanocomposites are prepared by a facile sol-gel method. Extensive tests are employed to characterize the textural and structural properties of samples. It is determined that perovskite particles are well dispersed on the surface of Pal with excellent NH 3 adsorption. The impacts of various Ni doping on the NO x conversion under visible light irradiation are investigated. Results indicate that when x is less than 0.4, LaFe 1-x Ni x O 3 remains a perovskite solid solution supported uniformly on the Pal surface. When x is beyond 0.4, LaNiO 3 phase co-precipitates and forms a coherent heterojunction of LaNiO 3 /LaFe 0.6 Ni 0.4 O 3 on Pal. Photo-assisted selected catalytic reduction (Photo-SCR) of NO results show that the denitrification performance varies with the Ni content, and more than 90% of NO molecules can be reduced when x = 0.5 in low temperature range of 150–250 °C. [ABSTRACT FROM AUTHOR]

In this study, the role of the noble metals Pt and Rh (0.5 wt.%) for the selective reduction of NO into N 2 is evaluated by the transient TAP technique and in-situ spectroscopy using a commercial stable ceria support (denoted as CZ) and applying isotopically labelled 15 NO and 18 O 2 . The transient operation was mimicked by multi-pulse oxidation (using O 2 or NO) and reduction cycles (using CO, H 2 , C 3 H 6 and C 3 H 8 ), while following quantitatively the catalyst and reactants response. Pt and Rh significantly lowered the temperature of CZ reduction. CO and H 2 only reduce the surface of CZ, while a 2.5 times deeper reduction was achieved by the hydrocarbons C 3 H 6 and C 3 H 8 , removing also lattice oxygen. Pt and Rh also promoted carbon deposition after surface reduction. Rh was a more active promoter than Pt, while propene was more reactive than propane over both metals. During the NO reduction the pre-reduced CZ support became gradually re-oxidised and after filling 70–80% of the oxygen vacancies the NO started to appear in the product mixture. In the presence of carbon deposits the lattice oxygen of the CZ reacted with the carbon keeping the CZ in a reduced state, extending the NO decomposition process as long as the carbon was present. The reduction of NO over pre-reduced noble metal/CZ showed a selective formation N 2 , while N 2 O and NO 2 were never observed. During the NO reduction process some unidentified N-species remained on the catalyst, the amount depending on the type of catalyst, but finally all nitrogen was released as N 2 . The presence of the noble metal led less unidentified N-species on the CZ surface and to a faster N 2 formation rate than that over the bare CZ. [ABSTRACT FROM AUTHOR]

A re-investigation of the interaction with NO of the small tetraheme protein cytochrome c554 (C554) from Nitrosomonas europaea has shown that the 5-coordinate heme II of the two- or four-electron-reduced protein will nitrosylate reversibly. The process is first order in C554, first order in NO, and second-order overall. The rate constant for NO binding to the heme is 3000 ± 140 M−1s−1, while that for dissociation is 0.034 ± 0.009 s−1; the degree of protein reduction does not appear to significantly influence the nitrosylation rate. In contrast to a previous report (Upadhyay AK, et al. J Am Chem Soc 128:4330, 2006), this study found no evidence of C554-catalyzed NO reduction, either with C5542- or with C5544-. Some sub-stoichiometric oxidation of the lowest potential heme IV was detected when C5544- was exposed to an excess of NO, but this is believed to arise from partial intramolecular electron transfer that generates {Fe(NO)}8 at heme II. The vacant heme II coordination site of C554 is crowded by three non-bonding hydrophobic amino acids. After replacing one of these (Phe156) with the smaller alanine, the nitrosylation rate for F156A2− and F156A4− was about 400× faster than for the wild type, though the rate of the reverse denitrosylation process was almost unchanged. Unlike in the wild-type C554, the 6-coordinate low-spin hemes of F156A4− oxidized over the course of several minutes after exposure to NO. Concomitant formation of N2O could explain this heme oxidation, though alternative explanations are equally plausible given the available data. [ABSTRACT FROM AUTHOR]

The biological pattern of plants' nitrous oxide (N2O) generation is not well understood because plant cells cannot form N2O from nitric oxide (NO) reduction. Hypothetically, we consider that plant-endophytic co-denitrification is potentially capable of making up for the functional loss of NO reduction in the plant cell and is thus the source of plant-derived N2O. In order to test the above hypothesis, field-cultured soybean seedlings and aseptic-cultured seedlings were used to establish plant holobionts with differentially established endophytes. The N2O fluxes, copies of the bacterial NO reductase encoding gene, and a diversity of endophytic denitrifying bacteria of these holobionts were observed by gas chromatography, real-time PCR, and 16s rDNA sequencing. The flux of N2O by the field seedlings was significantly higher than the fluxes of the aseptic seedlings and bulk soil. The N2O flux of the soybean seedlings was significantly correlated to the abundance of the bacterial NO reductase encoding gene. Eleven genera of denitrifying bacteria were observed in the soybean seedlings, and among them, two genera of aerobic denitrifying bacteria were specifically associated with colonizing plant samples. In this work we have also showed that plant N2O emission is affected by the abundance of total endophytic denitrifying bacteria. We conclude that plant sourced N2O is cooperatively generated by the plant-endophyte symbiotic system in which endophytic denitrifying bacteria help plants to emit N2O by taking over the NO--N2O reduction process. [ABSTRACT FROM AUTHOR]

Morphology of 3D TiO 2 support was regulated by modulating the hydrothermal time. Notably, the increase of hydrothermal time could greatly promote the transformation of rod-like TiO 2 to flower-like TiO 2 , while the continuous increase of hydrothermal time damaged the integrity of flower-like TiO 2 and led to the appearance of large TiO 2 particles. After that, a series of CeO 2 -WO 3 /TiO 2 catalysts were prepared by a typical impregnation method. The catalytic performance of these CeO 2 -WO 3 /TiO 2 catalysts for the selective catalytic reduction of nitrogen oxides (NH 3 -SCR) verified that NO x conversion was greatly related to morphological integrity of flower-like TiO 2 . Prominently, activity of CeO 2 -WO 3 /TiO 2 -8 catalyst was still excellent after introducing H 2 O and SO 2 , and thus the combined CeO 2 -WO 3 /TiO 2 -8 catalyst showed high catalytic activity and good resistance to H 2 O and SO 2 . Various characterizations indicated that the integrity of flower-like structure could evidently alter the surface atomic ratio of Ce 3+ /(Ce 3+  + Ce 4+ ) as well as acid sites. With the increase of surface atomic ratio of Ce 3+ /(Ce 3+  + Ce 4+ ), the SCR performance of the catalysts was obviously improved. In short, the superior catalytic performance of CeO 2 -WO 3 /TiO 2 for the SCR of NO x was related to the morphology of TiO 2 support, the highly dispersed active species, the valence of Ce, acid sites and lots of surface adsorbed oxygen. [ABSTRACT FROM AUTHOR]

The endothelium exerts many vasoprotective effects that are largely mediated by release of nitric oxide (NO). Endothelial dysfunction represents an early but reversible step in atherosclerosis and is characterized by a reduction in the bioavailability of NO. Previous studies have shown that eicosapentaenoic acid (EPA), an omega-3 fatty acid (O3FA), and statins individually improve endothelial cell function, but their effects in combination have not been tested. Through a series of in vitro experiments, this study evaluated the effects of a combined treatment of EPA and the active metabolite of atorvastatin (ATM) on endothelial cell function under conditions of oxidative stress. Specifically, the comparative and time-dependent effects of these agents on endothelial dysfunction were examined by measuring the levels of NO and peroxynitrite (ONOO − ) released from human umbilical vein endothelial cells (HUVECs). The data suggest that combined treatment with EPA and ATM is beneficial to endothelial function and was unique to EPA and ATM since similar improvements could not be recapitulated by substituting another O3FA docosahexaenoic acid (DHA) or other TG-lowering agents such as fenofibrate, niacin, or gemfibrozil. Comparable beneficial effects were observed when HUVECs were pretreated with EPA and ATM before exposure to oxidative stress. Interestingly, the kinetics of EPA-based protection of endothelial function in response to oxidation were found to be significantly different than those of DHA. Lastly, the beneficial effects on endothelial function generated by combined treatment of EPA and ATM were reproduced when this study was expanded to an ex vivo model utilizing rat glomerular endothelial cells. Taken together, these findings suggest that a combined treatment of EPA and ATM can inhibit endothelial dysfunction that occurs in response to conditions such as hyperglycemia, oxidative stress, and dyslipidemia. [ABSTRACT FROM AUTHOR]

Solanum xanthocarpum Schrad. & H. Wendl is a prickly herb, extensively known for its medicinal properties across the tribal and rural parts of India. Its efficacy in lung disorders and related respiratory diseases is well established in Ayurveda. In present time, cancer is considered as a significant challenge and metastasis is the most devastating hallmark in cancer progression. The present study evaluates the effects of whole plant and root of S. xanthocarpum on highly metastatic human lung adenocarcinoma cell line A549. Extracts were prepared using ethyl acetate and chloroform in various dilutions. Cytotoxicity of the plant and root extracts was analyzed. Wound healing assay was employed to check the effects on migration of highly metastatic A549 cells. Moreover, plants effects on cellular superoxide anion O2.- and nitric oxide (NO) quantities were evaluated to check effects on the redox regulation of the cell. All the extracts of Solanum xanthocarpum are not cytotoxic. However, all the extracts efficiently inhibit migration of A549 cells. The whole plant in ethyl acetate treatment shows a three-fold decrease in wound healing capacity of the cells. Ethyl acetate extracts of the plant show potential inhibition of NO2- and all the extracts show decreased levels of O2.- at higher concentrations. [ABSTRACT FROM AUTHOR]

Photocatalytic ammonia synthesis is of great importance but remains very challenging in photocatalysis. Here, we fabricated a photocatalytic reaction system for the efficiently photocatalytic nitrate reduction to ammonia under UV irradiation using PdSn/NiO/NaTaO 3 :La as a photocatalyst in the presence of formic acid. Several important factors of the photocatalytic performance were investigated, including initial concentration of the nitrate solution, initial pH value and cocatalyst loadings. Nitrate conversion reaches 100% and ammonia selectivity is 72% over the optimum photocatalyst with 5% bimetallic PdSn alloy and 0.2% NiO loadings. The outstanding performance of photocatalyst can be ascribed to both the strong adsorption of nitrite on NiO and the efficient separation of electron-hole pairs by PdSn bimetallic alloy. Besides as the hole scavenger, formic acid also provides not only carboxyl anion radicals for nitrate reduction but also the in-situ buffer effect on ammonia formation. These results give inspiration for designing the reactive system with efficient photocatalytic ammonia synthesis. [ABSTRACT FROM AUTHOR]

Membrane-integrated nitric oxide reductase (NOR) reduces nitric oxide (NO) to nitrous oxide (N 2 O) with protons and electrons. This process is essential for the elimination of the cytotoxic NO that is produced from nitrite (NO 2 − ) during microbial denitrification. A structure-guided mutagenesis of NOR is required to elucidate the mechanism for NOR-catalyzed NO reduction. We have already solved the crystal structure of cytochrome c -dependent NOR (cNOR) from Pseudomonas aeruginosa . In this study, we then constructed its expression system using cNOR-gene deficient and wild-type strains for further functional study. Characterizing the variants of the five conserved Glu residues located around the heme/non-heme iron active center allowed us to establish how the anaerobic growth rate of cNOR-deficient strains expressing cNOR variants correlates with the in vitro enzymatic activity of the variants. Since bacterial strains require active cNOR to eliminate cytotoxic NO and to survive under denitrification conditions, the anaerobic growth rate of a strain with a cNOR variant is a good indicator of NO decomposition capability of the variants and a marker for the screening of functionally important residues without protein purification. Using this in vivo screening system, we examined the residues lining the putative proton transfer pathways for NO reduction in cNOR, and found that the catalytic protons are likely transferred through the Glu57 located at the periplasmic protein surface. The homologous cNOR expression system developed here is an invaluable tool for facile identification of crucial residues in vivo , and for further in vitro functional and structural studies. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The addition of ceria could raise the higher valence state rate of manganese. • Higher valence state of manganese was beneficial for De-NOx. • The addition of ceria was in favor of the NO oxidation. • Mechanism of Ce improving effect on Mn–Ce/ASC catalysts was systematically depicted. Abstract Mn–Ce mixed oxide was loaded onto activated semi-coke (ASC) via impregnation method and the low temperature selective catalytic reduction (SCR) of NO with NH 3 was investigated. The NO conversion and NO oxidation rates were both influenced by the ratios of Ce/(Mn + Ce), and Mn–Ce(0.3)/ASC with loading 5% (mass ratio) Mn–Ce oxides performed the highest catalytic conversion rate of 96.6% and NO oxidation rate of 18.4% at 250 °C and GHSV = 6000 h−1. The changes of physical properties, microstructure, functional groups, crystal structure, surface atomic state, redox property and acid strength for the catalysts were characterized by BET, SEM, FT-IR, XRD, XPS, H 2 -TPR and NH 3 -TPD. The results showed that surface functional groups were increased after nitric acid treatment and abundant oxygen groups were observed on semi-coke surface, which were considered to be beneficial for the gas adsorption. Ce doping could raise the Mn4+/Mnx+ rate which played a vital role in catalytic reaction, enhancing the amount of weak and strong acid sites, increasing oxygen vacancies and accelerating the molecular oxygen turning into reactive oxygen species, which could enhance the NO oxidation activity thus contributed to the denitration efficiency. [ABSTRACT FROM AUTHOR]

Hepatic injury is a major event in liver surgery and may lead to liver cell apoptosis. Nitric oxide (NO) is an unstable, carbon-centered radical with a short half-time and a key role in molecular signaling. Increasing evidence demonstrates that NO plays an important role in the liver cell apoptosis caused by hepatic ischemia reperfusion (IR) injury and other liver damage. Our recent article summarized the association between elevated nitric oxide levels and hepatic cell apoptosis during liver injury. This article reviews the newest research progress for the relationship between decreased nitric oxide levels and hepatic cell apoptosis inhibition during liver injury. It is shown that decreased NO level can influence liver apoptosis by promoting or inhibiting the signaling pathway involving the caspase family, BCL-2, mitochondria, oxidative stress, death receptors, and mitogen activated protein kinases, etc. This review outlines the literature basis for clinical application of anti-apoptosis treatment to relieve organ injury following liver surgery. NO-related drugs appear to be helpful in clinical treatment of liver diseases. Highlights • This article reviews the newest research progress for the relationship between decreased nitric oxide levels and hepatic cell apoptosis inhibition during liver injury. • It is shown that decreased NO level can influence liver apoptosis by promoting or inhibiting the signaling pathway involving the caspase family, BCL-2, mitochondria, oxidative stress, death receptors, and mitogen activated protein kinases, etc. • This review outlines the literature basis for clinical application of anti-apoptosis treatment to relieve organ injury following liver surgery. • These review suggested that NO-related drugs appear to be helpful in clinical treatment of liver diseases. [ABSTRACT FROM AUTHOR]

Self-supported ZSM-5 zeolite monolith foams (ZMFs) with different Si/Al ratios have been successfully prepared by hydrothermal synthesis with a polyurethane foam (PUF) template followed by calcination in air at 550 °C to harden. Cu or Mn have been introduced on preformed ZMF samples to obtain monolithic catalysts that have been fully characterized by morphological (XRD and SEM), textural (BET and pore size distribution), mechanical (compressive strength) and chemical (ICP-MS) analyses, and eventually tested in the Selective Catalytic Reduction of NO with NH 3 in the temperature range 100–450 °C. The zeolite monolith foams are characterized by a well crystallized ZSM-5 structure, a BET surface area ca. 420 m 2  g −1 and remarkable mechanical resistance even without any binder. Those structured catalysts show specific catalytic activity in line with powdered counterparts, but they can guarantee improved NO conversion due to the higher amount of catalyst per unit volume of reactor and to their superior mass transfer coefficients coupled to low internal diffusion limitations. [ABSTRACT FROM AUTHOR]

Abstract: A series of ceria‐supported Rh nanoparticles (NPs) that have various particle sizes of 2–7 nm was prepared to investigate the size effect of Rh NPs on NO reduction in NO–CO–C3H6–O2 under stoichiometric conditions. The turnover frequency (TOF) for NO reduction on Rh NPs increased drastically according to their particle size. The strong size dependence of the TOF was attributed to the oxidation states of Rh NPs but not to particle geometries, which include fractions of surface local sites (e.g., corner, edge, plane) and the surface crystal structures (e.g., Rh(1 1 1), (1 0 0)). The variation of the TOF with the Rh metal fraction suggested that Rh metal ensembles are highly active species for NO reduction. [ABSTRACT FROM AUTHOR]

Supported Ir catalysts effectively catalyzed the NO reduction with CO and C 3 H 6 under slight lean and high-temperature conditions, although supported Pt and Pd showed the activity for NO reduction in low temperature region with narrow window. The NO reduction activity of supported Ir catalysts was quite different depending on the support oxide. Among them, Ir/SiO 2 and Ir/CeO 2 were the highest and lowest active catalysts, respectively. Although no relationship between the reducibility estimated by H 2 -TPR and the NO reduction activity was observed, TPO measurements revealed that the stability of Ir species in catalytically active reducing state is a key factor to determine the NO reduction activity. In situ FT-IR spectroscopy confirmed the formation of catalytically active reduced Ir species during the reaction. From the comparison of the wavenumber of IR band due to adsorbed CO species with the NO reduction activity, too strong Ir – support interaction causes the formation of stable Ir oxide species, resulting in the depression of NO reduction activity. The role of support oxide for Ir catalyst was concluded to stabilize the Ir species in catalytically active reducing state created during the reaction via the Ir – support interaction. [ABSTRACT FROM AUTHOR]