Approche expérimentale par ESI/ITMS et théorique des affinités cationiques (Na+) d'acides aminés, de bases nucléiques et de nucléosides

The reactivity of modified and unmodified amino acids, nucleobases and nucleosides towards sodium was studied. Sodium cationic affinities (SCA) were determined first by mass spectrometry with ESI/ITMS, then by ab initio calculations. The experimental method allowed us to determine the SCA values for amino acids, nucleobases and nucleosides by Cooks kinetic method by decomposing the studied dimers in gas phase. Ab initio calculations allowed us to determine the SCA and the structure of the cationized molecules formed in gas phase. After determination of the best calculation system (DFT), the very good correlation between experimental and theoretical results allowed us to determine the cationisation sites and so the structures of modified and unmodified amino acids, nucleobases and nucleosides.Cette thèse consiste en l'étude de la réactivité en phase gazeuse d'acides aminés, de bases nucléiques et de nucléosides modifiés et non modifiés vis à vis du cation sodium. Les affinités cationiques ont été déterminées expérimentalement par couplage ESI/ITMS et théoriquement, par calculs ab initio d'énergie. La méthode expérimentale permet de déterminer les valeurs des affinités cationiques des biomolécules en étudiant la décomposition des dimères cationisés formés en phase gazeuse selon la méthode de Cooks. Les calculs ab initio permettent de déterminer les affinités cationiques et les structures des complexes formés en phase gazeuse. Après avoir montré que l'utilisation de la théorie de la fonctionnelle de la densité (DFT) avec la fonctionnelle B3P86 était bien adaptée à notre problématique, l'excellente corrélation obtenue entre les résultats expérimentaux et théoriques a permis de déterminer les sites privilégiés de cationisation et donc les structures cationisées des acides aminés, des bases nucléiques et des nucléosides modifiés et non modifiés en phase gazeuse

Approche expérimentale par ESI/ITMS et théorique des affinités cationiques (Na+) d'acides aminés, de bases nucléiques et de nucléosides

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Artists' pigments in illuminated medieval manuscript

International audienceWhen illuminated, manuscripts can be considered as galleries of paintings, kept in better conditions than any other artworks from the Middle Age. They can give precious information about the palettes used by medieval painters. Up to now, the chemical analyses contribute to a more complete understanding of the medieval illuminated manuscript. As sampling can be dangerous for so delicate works of art with very thin paint layers, a non-invasive approach has to be chosen. This talk will present the use of chemical imaging to study a middle 15 th century illuminated manuscript leaf on parchment illustrating Petrarch's text and representing Dame Fortune (Figure 1). We used the combination of visible/near infrared (400-1000 nm) reflectance imaging spectroscopy and X-ray fluorescence imaging spectroscopy to reveal the palette used by ancient illuminators, including inorganic pigments (mineral or synthetic) and organic dyes. Moreover, it was possible to determine the original pigments used to paint the hidden coat of arms

Artists' pigments in illuminated medieval manuscript

International audienceWhen illuminated, manuscripts can be considered as galleries of paintings, kept in better conditions than any other artworks from the Middle Age. They can give precious information about the palettes used by medieval painters. Up to now, the chemical analyses contribute to a more complete understanding of the medieval illuminated manuscript. As sampling can be dangerous for so delicate works of art with very thin paint layers, a non-invasive approach has to be chosen. This talk will present the use of chemical imaging to study a middle 15 th century illuminated manuscript leaf on parchment illustrating Petrarch's text and representing Dame Fortune (Figure 1). We used the combination of visible/near infrared (400-1000 nm) reflectance imaging spectroscopy and X-ray fluorescence imaging spectroscopy to reveal the palette used by ancient illuminators, including inorganic pigments (mineral or synthetic) and organic dyes. Moreover, it was possible to determine the original pigments used to paint the hidden coat of arms

XRF and reflectance hyperspectral imaging on a 15th century illuminated manuscript: combining imaging and quantitative analysis to understand the artist’s technique

International audienceWe present here the combination of in situ non invasive techniques to investigate a precious 15th century illuminated manuscript of Petrarch’s work, De remediis utriusque fortunae held in the Méjanes library in Aix-en-Provence (France). X-Ray fluorescence spectroscopy, mapping and point analysis, and visible reflectance hyperspectral imaging allow an unprecedented analysis of this manuscript. They provide new clues for its attribution by revealing a partly hidden coat of arms and describing the illuminator’s palette and techniques in detail. We reveal the identity of the first possessor of this manuscript, Tanguy IV du Châtel, known as a 15th century bibliophile close to Louis XI. This information is a further element contributing to the attribution of the richly illuminated folio 6 of this manuscript to François Le Barbier. Pigments and dyes used for this folio have been investigated with particular emphasis on the study of the superimposed colours thus providing a better understanding of the artist’s technique and know-how

Investigations of the fragmentation pathways of benzylpyridinium ions under ESI/MS conditions.

International audienceBenzylpyridinium ions are often used as 'thermometer ions' in order to evaluate the internal energy distribution of the ions formed in sources of mass spectrometers. However, the detailed fragmentation pathways of these parent ions were not well established. In particular, fragmentation involving a rearrangement (RR) process may be influencing the simulated distribution curves. In a previous study, we suggested that such RR actually occurred under electrospray ionization/mass spectrometry (ESI/MS) and fast atom bombardment/mass spectrometry (FAB/MS) experiments. Here, we present a systematic study of different substituted benzylpyridinium ions. Theoretical calculations showed that RR fragmentation leading to substituted tropylium ions could occur under 'soft ionization' conditions, such as ESI or FAB. Experimental results obtained under gas-phase reactivity conditions showed that some substituted benzylpiridinium compounds actually undergo RR fragmentations under ESI/MS conditions. Mass-analyzed kinetic experiments were also carried out to gain information on the reaction pathways that actually occur, and these experimental results are in agreement with the reaction pathways theoretically proposed

Identification of quinoline, carboline and glycinamide compounds in cow milk using HRMS and NMR

International audienceThe aim of this work was to characterise new UV-absorbing compounds (UAC) in cow milk in order to gain an overview of the molecular diversity of the minor bioactive constituents, that could be used to trace animal feed or that potentially affect milk quality. UAC were extracted from lyophilized milks, partitioned using SPE C-18 cartridges, purified by semi-preparative HPLC then analysed by HPLC/DAD/HRMS in both ESI− and ESI+ ionisation mode. Compounds that remained unidentified after comparison with UV and MS databases were analysed by 1D and 2D NMR techniques. The identification and structural elucidation of N-cinnamoylglycine, 2,4-, 2,6-, 2,8-quinolinediols, and 1-methyl-3-carboxy-beta-carboline are described

Pig farmers attitudes towards sick/injured pigs in relation to care and rehabilitation, the use of medication and euthanasia

Antibiotic (AB) resistance is a major concern worldwide. Knowledge about potential drivers of AB use and prescribing practices in the pig industry is required to address problems of mis and over use. We hypothesised that pig farmers attitudes towards the treatment and care of injured or sick pigs may influence their use of AB. Semi-structured face-to-face interviews were conducted with 30 producers who managed integrated pig units in Ireland and which supplied records to the Teagasc PigSys database. Ethical approval was obtained and pig producers were invited for interview by their Teagasc pig advisor. Consent was obtained at the time of the interview. Interviews with participants were recorded and transcribed using random numbers from 1 to 30, one per participant to ensure anonymity. Themes were then identified from the data. The importance of comfort and care in the rehabilitation of animals following injury was only expressed in relation to sows. Here the importance of straw bedding and a solid floor in ensuring recuperation from lameness/injury was mentioned by several producers (n=7). The relevance of analgesics to recovery from illness or injury was only mentioned by 2 producers who used pain relief for sows that were ‘sick after farrowing’. Injectable ABs were the most common method of treating illness or injury (n=12), followed by euthanasia (n=7). The practice of euthanising pigs was driven by economic (n=6) or humane grounds (n=9). The latter also expressed the belief that it was more humane to euthanise than to hospitalise sick or injured pigs. However, there was a general dislike for the practice of euthanasia. Many producers mentioned that it is too expensive to call a vet to treat or to euthanise sick or injured pigs. Only one producer used a vet to euthanise pigs. Several producers did not agree with the use of hospital pens (n=7) either because they believed that pigs are usually abandoned/forgotten in such pens (n=2) or because hospital pens are places where diseases are harbored and recirculated through the herd. Almost half of the producers expressed the view that medications (in-feed and/or injections) were the only solution to deal with pig health problems and to ensure good welfare. A 3rd of producers believed that the only solution to serious diseases challenges was to de-stock the herd. Low profit margins and lack of awareness of the role which husbandry and the environment have to play in the prevention of diseases as well as the role which comfort and care of pigs play in the recovery process are major barriers to reducing the reliance on medication in the pig industr