Monoxyde d'azote

Le monoxyde d'azote, oxyde azotique, oxyde nitrique ou NO est un composé chimique formé d'un atome d'oxygène et d'un atome d'azote. C'est un gaz dans les conditions normales de température et de pression. C'est un important neurotransmetteur chez les mammifères ; dissous, il franchit facilement les membranes biologiques et passe d'une cellule à l'autre, constituant un . Le monoxyde d'azote (NO) ne doit pas être confondu avec d'autres oxydes d'azote, tels le protoxyde d'azote NO, que l'on appelle « gaz hilarant », et qui est un anesthésique général, ou le dioxyde d'azote NO, gaz rouge-brun extrêmement irritant et nocif, qui se forme par oxydation rapide de NO par l'oxygène de l'air. Sa grande réactivité (en phase soluble notamment) vis-à-vis des composés radicalaires comme l'oxygène moléculaire ou l'anion superoxyde est due au fait qu'il est lui-même un composé radicalaire . En milieu biologique, sa demi-vie est estimée entre une et cinq secondes, voire trente secondes. Les peroxyn

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ChE-410: Catalysis for emission control and energy processes

The course is an introduction to heterogeneous catalysis for environmental protection and energy production. It focusses on catalytic exhaust gas cleaning as well as catalytic systems relevant for gaseous and liquid fuel production. The course ends with two days of experimental exercises at PSI.

MSE-101(a): Materials:from chemistry to properties

Ce cours permet l'acquisition des notions essentielles relatives à la structure de la matière, aux équilibres et à la réactivité chimique en liaison avec les propriétés mécaniques, thermiques, électriques et magnétiques des matériaux.

MSE-234: Mechanical behaviour of materials

Ce cours est une introduction au comportement mécanique, à l'élaboration, à la structure et au cycle de vie des grandes classes de matériaux de structure (métaux, polymères, céramiques et composites)

Diamond-Based Nanoscale Quantum Relaxometry for Sensing Free Radical Production in Cells

Mayeul Sylvain Chipaux, Hoda Shirzad

Diamond magnetometry makes use of fluorescent defects in diamonds to convert magnetic resonance signals into fluorescence. Because optical photons can be detected much more sensitively, this technique currently holds several sensitivity world records for room temperature magnetic measurements. It is orders of magnitude more sensitive than conventional magnetic resonance imaging (MRI) for detecting magnetic resonances. Here, the use of diamond magnetometry to detect free radical production in single living cells with nanometer resolution is experimentally demonstrated. This measuring system is first optimized and calibrated with chemicals at known concentrations. These measurements serve as benchmarks for future experiments. While conventional MRI typically has millimeter resolution, measurements are performed on individual cells to detect nitric oxide signaling at the nanoscale, within 10-20 nm from the internalized particles localized with a diffraction limited optical resolution. This level of detail is inaccessible to the state-of-the-art techniques. Nitric oxide is detected and the dynamics of its production and inhibition in the intra- and extracellular environment are followed.

WILEY-V C H VERLAG GMBH2022

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Do synthetic Fe-zeolites mimic biological Fe-porphyrins in reactions with nitric oxide?

Bryan Bromley, Lioubov Kiwi

Iron containing ZSM-5 zeolites is extremely active in nitrous oxide decomposition. This reaction involves atomic oxygen species known as "alpha oxygen" on iron sites. Despite the multiple techniques devoted to its characterization, the active sites' structure remains nevertheless unknown. Herein, these centers are quantified via surface titration by nitrous oxide followed by temperature programmed desorption and characterized via nitric oxide probe molecule followed by infrared spectroscopy. In this latter case, two mono-nitrosyl species differing in the bonds' geometry are observed on the iron centers. Moreover, upon NO evacuation, the two corresponding IR bands suddenly transit to lower wavenumbers. A mirror trend is also reported in biology when NO interacts with iron porphyrins and explained in terms of linear to bent Fe-N-O modification. This structural change is reversible upon addition/evacuation of NO. In the present report, the same reversible nitrosyl transition is observed for Fe-ZSM-5. Based on the close analogies found, the active site's structure in Fe-ZSM-5 is built-up from the porphyrinatoiron(II) model. © 2010 Elsevier B.V. All rights reserved.

Elsevier2010

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Electronic Population Transfer via Impulsive Stimulated X-Ray Raman Scattering with Attosecond Soft-X-Ray Pulses

Andre Al Haddad, Christoph Bostedt, Xiang Li, Siqi Li, Solène Oberli

Free-electron lasers provide a source of x-ray pulses short enough and intense enough to drive nonlinearities in molecular systems. Impulsive interactions driven by these x-ray pulses provide a way to create and probe valence electron motions with high temporal and spatial resolution. Observing these electronic motions is crucial to understand the role of electronic coherence in chemical processes. A simple nonlinear technique for probing electronic motion, impulsive stimulated x-ray Raman scattering (ISXRS), involves a single impulsive interaction to produce a coherent superposition of electronic states. We demonstrate electronic population transfer via ISXRS using broad bandwidth (5.5 eV full width at half maximum) attosecond x-ray pulses produced by the Linac Coherent Light Source. The impulsive excitation is resonantly enhanced by the oxygen 1s -> 2 pi* resonance of nitric oxide (NO), and excited state neutral molecules are probed with a time-delayed UV laser pulse.

AMER PHYSICAL SOC2020

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Azote

L'azote est l'élément chimique de numéro atomique 7, de symbole N (du latin nitrogenium). C'est la tête de file du groupe des pnictogènes. Dans le langage courant, l'azote désigne le corps simple N