Le sevrage difficile et prolongé de la ventilation mécanique (à propos de 67 patients hospitalisés dans le service de réanimation de l'hôpital de Bligny entre 1993 et 1999)

LE KREMLIN-B.- PARIS 11-BU Méd (940432101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

PyC2MC: An Open-Source Software Solution for Visualization and Treatment of High-Resolution Mass Spectrometry Data

International audienc

PyC2MC: an open-source software solution for visualization and treatment of high-resolution mass spectrometry data

Complex molecular mixtures are encountered in almost all research disciplines, such as biomedical ‘omics, petroleomics, and environmental sciences. State-of-the-art characterization of sample materials related to these fields, deploying high-end instrumentation, allow for gathering humongous quantity of molecular composition data. One established technological platform is ultrahigh-resolution mass spectrometry, e.g., Fourier-transform mass spectrometry (FT-MS). However, the huge amounts of data acquired in FT-MS often result in tedious data treatment and visualization. FT-MS analysis of complex matrices can easily lead to single mass spectra with more than 10,000 attributed unique molecular formulae. Sophisticated software solutions to conduct these treatment and visualization attempts from commercial and non-commercial origins exist. However, existing applications have distinct drawbacks, such as focusing on only one type of graphic representation, being unable to handle large datasets, or not being publicly available. In this respect, we developed a software, within the international complex matrices molecular characterization joint lab (IC2MC), named “python tools for complex matrices molecular characterization” (PyC2MC). This piece of software will be open-source and free to use. PyC2MC is written under python 3.9.7 and relies on well-known libraries such as pandas, NumPy, or SciPy. It is provided with a graphical user interface developed under PyQt5. The two options for execution, 1) user-friendly route with pre-packed executable file or 2) running the main python script through a Python interpreter, ensure a high applicability but also an open characteristic for further development by the community. Both are available on the GitHub platform (https://github.com/iC2MC/PyC2MC_viewer)

A simple, low-cost and fast Peltier thermoregulation set-up for electrophysiology

Most of the parameters recorded in electrophysiology are strongly temperature dependent. In order to control temperature fluctuations we have built a system that ensures an accurate thermoregulation of the recording chamber. Temperature of physiological preparations can be changed relatively quickly (about 8°C/min) and with a good accuracy (±0.5°C) without inducing thermal oscillations. Contrary to other thermoregulating devices, the temperature regulation is not carried out through the perfused medium but directly at the bottom of the chamber where a 3-cm2 Peltier element has been placed. The element is driven by a dedicated electronic device which controls the amount and the direction of the current flowing across the Peltier thermocouple. All construction details and the appropriate electrical circuits are provided. Using this home-made device, the steady-state chamber temperature could be precisely monitored with a resolution of ±0.1°C in a range of 0–40°C. This set-up was tested in experiments designed to evaluate the temperature dependence of synaptic transmission in the Torpedo nerve–electroplate synapses and of calcium currents recorded from isolated nerve cells. This low-cost method is suitable for a wide range of applications.</p

Molecular Characterization of Aged Bitumen with Selective and Nonselective Ionization Methods by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry. 3. Investigation on Molecular Fractions Obtained by Gel Permeation Chromatography

Long-term aging of bitumen causes formation of oxidation products that can be associated with polar and strongly interacting functional groups leading to a tremendous influence on bitumen properties. This can lead to an aggregation of the most polar molecules in the asphaltene fraction. Other types of aggregation have also been described in the literature, with larger and more aliphatic compounds through wax interactions. These aggregate phases can be studied using gel permeation chromatography (GPC) for the separation of heavy petroleum products based on their molecular weight. Three molecular weight fractions of native bitumen and its aged state by a long-term pressure aging vessel (PAV-72h) were obtained with low molecular weight (LMW), medium molecular weight (MMW), and high molecular weight (HMW) fractions. To characterize oxidative aging on each fraction at the molecular level, Fourier transform ion cyclotron resonance (FTICR) was used. Indeed, the ultrahigh resolution and mass accuracy of this analyzer allow to attribute molecular formulas to each signal of complex matrices unambiguously. An electrospray ionization (ESI) source was used to selectively ionize acid molecules, while atmospheric pressure photoionization source (APPI) was used to have a nonselective ionization of low polarity molecules from bitumen. With both ionization sources, the LMW fraction exhibited the most aromatic and heteroelement-enriched molecules. In terms of variation with aging, the LMW fraction showed the most pronounced variations. Molecular maps evidenced the occurrence of low DBE oxidation markers for Oz and OzSy families. Low variations were observed on distributions of MMW and HMW fractions. Concerning HMW, these unexpected results, obtained by ESI and APPI ionization sources, may be due to a protection of the molecules against oxidation within aggregates. In addition, APPI results underlined that the higher molecular weight distribution containing most of the aggregate molecules was mainly composed of large aliphatic molecules. Overall, this study demonstrated that oxidation products corresponded to small and aliphatic molecules majorly found in the LMW fraction and that aggregated molecules form HMW fraction were relatively protected from oxidation

Speciation of Metals in Asphaltenes by High-Performance Thin-Layer Chromatography and Solid–Liquid Extraction Hyphenated with Elemental and Molecular Identification

International audienceAsphaltenes are among the most challenging components in petroleum processing because they contain high amounts of heteroatoms (i.e., S, N, O, V, and Ni) thought to be responsible for strong aggregation tendencies, precipitation, and fouling problems. The role of vanadium- and nickel-containing petroleum compounds (i.e., petroporphyrins) in aggregation and fouling is not completely understood because asphaltene composition and structure is still a subject of debate in the petroleum chemistry community. Characterization of asphaltenes, namely, molecular analysis that employs no chromatographic separation, often fails to reveal their comprehensive composition. The work herein presents asphaltene fractionation by (1) solid/liquid extraction, which allows for separation of single-core (“island”) and multicore (“archipelago”) structural motifs and by (2) high-performance thin layer chromatography (HPTLC) with cellulose as the stationary phase and DCM/MeOH as the eluent, which facilitates access to petroporphyrins. Characterization is performed by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and matrix-assisted laser desorption ionization Fourier transform ion cyclotron resonance mass spectrometry (MALDI FT-ICR MS). The results demonstrate that even with multiple separation steps, a large quantity of vanadyl porphyrins remains inaccessible for molecular analysis by MALDI FT-ICR MS, which raises the question of what portion of a complex sample of asphaltene can be revealed by ultrahigh resolution mass spectrometry. Furthermore, the results show that easily accessible porphyrins migrate with the solvent front in HPTLC. Thus, HPTLC can be used to isolate and identify “free” porphyrins not locked into asphaltene aggregates; however, further development of separation methods is required to access the most difficult and problematic asphaltene fractions, which do not migrate and impose analytical challenges due to their stronger aggregation tendency

Entre Baroque et Lumières : Saint-Évremond (1614-1703)

On parle de Saint-Évremond surtout pour rappeler qu’il fait partie des grands exilés de l’histoire mais son œuvre est rarement étudiée en tant que telle. Elle n’a notamment jamais fait l’objet d’une rencontre spécifique. Le colloque de Cerisy, dont nous présentons les Actes, entendait donc réparer un oubli. Des écrits de celui qui redoutait par-dessus tout de passer pour un « auteur » il convient en effet de souligner tout à la fois l’abondance – qui s’explique en partie par sa longévité – et l’importance : conteur, nouvelliste, chroniqueur autant que versificateur, Saint-Évremond fait aussi œuvre de moraliste, de philosophe, de critique, et notamment de critique musical, d’historien. Notre ambition a été d’envisager les domaines qui ont été jusqu’ici le moins fréquemment abordés, de renouveler l’approche de ceux qui ont déjà été traités, de souligner enfin la place que cet auteur occupe dans l’histoire des idées et dans l’évolution de la littérature des siècles classiques