Over the coming decades nitrous oxide (N2O) is expected to become a dominant greenhouse gas and atmospheric ozone depleting substance. In wastewater treatment systems, N2O is majorly produced by nitrifying microbes through biochemical reduction of nitrite (NO2(-)) and nitric oxide (NO). However it is unknown if the amount of N2O formed is affected by alternative NO redox reactions catalyzed by oxidative nitrite oxidoreductase (NirK), cytochromes (i.e., P460 [CytP460] and 554 [Cyt554 ]) and flavohemoglobins (Hmp) in ammonia- and nitrite-oxidizing bacteria (AOB and NOB, respectively). In this study, a mathematical model is developed to assess how N2O formation is affected by such alternative nitrogen redox transformations. The developed multispecies metabolic network model captures the nitrogen respiratory pathways inferred from genomes of eight AOB and NOB species. The performance of model variants, obtained as different combinations of active NO redox reactions, was assessed against nine experimental datasets for nitrifying cultures producing N2O at different concentration of electron donor and acceptor. Model predicted metabolic fluxes show that only variants that included NO oxidation to NO2(-) by CytP460 and Hmp in AOB gave statistically similar estimates to observed production rates of N2O, NO, NO2(-) and nitrate (NO3(-)), together with fractions of AOB and NOB species in biomass. Simulations showed that NO oxidation to NO2(-) decreased N2O formation by 60% without changing culture's NO2(-) production rate. Model variants including NO reduction to N2O by Cyt554 and cNor in NOB did not improve the accuracy of experimental datasets estimates, suggesting null N2O production by NOB during nitrification. Finally, the analysis shows that in nitrifying cultures transitioning from dissolved oxygen levels above 3.8 ± 0.38 to <1.5 ± 0.8 mg/L, NOB cells can oxidize the NO produced by AOB through reactions catalyzed by oxidative NirK.
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Talanta
January 2025
College of Chemistry and Materials Science, Hunan Engineering Research Center for Monitoring and Treatment of Heavy Metals Pollution in the Upper Reaches of Xiangjiang River, Hengyang Normal University, Hengyang, 421001, China. Electronic address:
The accurate and sensitive quantification of hydroxyl radical (·OH) and glucose is necessary for disease diagnosis and health guidance, but still challenging owing to the low concentration of ·OH and poor water solubility of fluorescent probes. In addition, fluorescent probes may cause secondary pollution to the environment. Here an organic cage was reported as a sensitive fluorescent probe for ·OH and glucose in aqueous solution without serious secondary pollution.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Martin-Luther-Universitat Halle-Wittenberg, Department of Chemistry, Kurt-Mothes-Str. 2, 06120, Halle, GERMANY.
A pronounced nucleophilicity in combination with a distinct redox non-innocence is a unique feature of a coordinated ligand, which in the current case, leads to unprecedented carbon-centered reactivity patterns: A carbodiphosphorane-based (CDP) pincer-type rhodium complex allows to cleave two C-Cl-bonds of geminal dichlorides via two consecutive SN2-type oxidative additions resulting in the formation of a stabilized carbene fragment. In the presence of a suitable reductant the carbene fragment can even be converted into olefines or hydrodehalogenation products in a catalytic reaction. The developed method can also be used to convert chlorofluorocarbons (CFCs) such as CH2ClF to fluoromethane and methane.
View Article and Find Full Text PDFBiomed Pharmacother
January 2025
Department of Experimental Medicine, Sapienza University of Rome, Rome 00161, Italy. Electronic address:
The abundance and behaviour of all hematopoietic components display daily oscillations, supporting the involvement of circadian clock mechanisms. The daily variations of immune cell functions, such as trafficking between blood and tissues, differentiation, proliferation, and effector capabilities are regulated by complex intrinsic (cell-based) and extrinsic (neuro-hormonal, organism-based) mechanisms. While the role of the transcriptional/translational molecular machinery, driven by a set of well-conserved genes (Clock genes), in nucleated immune cells is increasingly recognized and understood, the presence of non-transcriptional mechanisms remains almost entirely unexplored.
View Article and Find Full Text PDFDalton Trans
January 2025
Hubei Key Laboratory for Processing and Application of Catalytic Materials, Huanggang Normal University, Huanggang 438000, China.
Incorporating non-electrochemically active elements (such as Zn and Mg) into the framework of active components can enhance structural stability, leading to improved cycling performance. However, limited research has been conducted on the impact of varying doping concentrations. In this study, we conducted a comprehensive analysis of how different levels of Mg doping in Co(OH) affect the supercapacitor performance.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
Department of Chemistry, University of Rajasthan, Jaipur, Rajasthan, India, 302004.
The present investigation delves into the redox reaction between -chlorophenol (-CP) and hexacyanoferrate(III) [HCF(III)], catalyzed by Ag(I) in an alkaline environment. Findings reveal a first-order dependence on both -CP and the oxidant, and the reaction rate showcased a first-order reaction towards Ag(I), which was further amplified by the medium as per the equation = + [OH]. Interestingly, the ionic strength remained unchanged throughout the reaction, exerting no discernible effect on the reaction rate.
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