69 research outputs found

    Comparability of Raman Spectroscopic Configurations: A Large Scale Cross-Laboratory Study

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    This is the final version. Available on open access from the American Chemical Society via the DOI in this recordThe variable configuration of Raman spectroscopic platforms is one of the major obstacles in establishing Raman spectroscopy as a valuable physicochemical method within real-world scenarios such as clinical diagnostics. For such real world applications like diagnostic classification, the models should ideally be usable to predict data from different setups. Whether it is done by training a rugged model with data from many setups or by a primary-replica strategy where models are developed on a 'primary' setup and the test data are generated on 'replicate' setups, this is only possible if the Raman spectra from different setups are consistent, reproducible, and comparable. However, Raman spectra can be highly sensitive to the measurement conditions, and they change from setup to setup even if the same samples are measured. Although increasingly recognized as an issue, the dependence of the Raman spectra on the instrumental configuration is far from being fully understood and great effort is needed to address the resulting spectral variations and to correct for them. To make the severity of the situation clear, we present a round robin experiment investigating the comparability of 35 Raman spectroscopic devices with different configurations in 15 institutes within seven European countries from the COST (European Cooperation in Science and Technology) action Raman4clinics. The experiment was developed in a fashion that allows various instrumental configurations ranging from highly confocal setups to fibre-optic based systems with different excitation wavelengths. We illustrate the spectral variations caused by the instrumental configurations from the perspectives of peak shifts, intensity variations, peak widths, and noise levels. We conclude this contribution with recommendations that may help to improve the inter-laboratory studies.COST (European Cooperation in Science and Technology)Portuguese Foundation for Science and TechnologyNational Research Fund of Luxembourg (FNR)China Scholarship Council (CSC)BOKU Core Facilities Multiscale ImagingDeutsche Forschungsgemeinschaft (DFG, German Research Foundation

    Alevinage, pollution et cloisonnement de l'espace fluvial dans les structures génétiques des populations de poisson : l'ombre commun, Thymallus thymallus, dans le Rhône au niveau de la Savoie

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    L'analyse de la variabilité allozymique des populations d'ombre commun du Rhône savoyard et de ses affluents fait apparaître de fortes différences entre sites malgré leur proximité. La variabilité observée à l'intérieur des populations semble résulter de l'introduction de gènes étrangers par alevinage depuis de nombreuses années. Les différences entre populations résulteraient par contre d'une modulation de l'impact génétique de ces alevinages par les conditions environnementales. L'altération du milieu physique, son cloisonnement par les barrages, et une pollution ponctuelle majeure apparaissent les éléments déterminants de ces structures génétiques qui seraient ainsi entièrement le fait de l'homme

    Mécanismes et étendue de la dispersion des crevettes d’eau douce (crustacea, decapoda) à l’échelle de la Guadeloupe : données de la génétique

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    Eppe R., Fièvet E. Mécanismes et étendue de la dispersion des crevettes d’eau douce (crustacea, decapoda) à l’échelle de la Guadeloupe : données de la génétique . In: Revue d'Écologie (La Terre et La Vie), tome 59, n°1-2, 2004. p. 359

    Alevinage, pollution et cloisonnement de l'espace fluvial dans les structures génétiques des populations de poisson : l'ombre commun, Thymallus thymallus, dans le Rhône au niveau de la Savoie

    No full text
    L'analyse de la variabilité allozymique des populations d'ombre commun du Rhône savoyard et de ses affluents fait apparaître de fortes différences entre sites malgré leur proximité. La variabilité observée à l'intérieur des populations semble résulter de l'introduction de gènes étrangers par alevinage depuis de nombreuses années. Les différences entre populations résulteraient par contre d'une modulation de l'impact génétique de ces alevinages par les conditions environnementales. L'altération du milieu physique, son cloisonnement par les barrages, et une pollution ponctuelle majeure apparaissent les éléments déterminants de ces structures génétiques qui seraient ainsi entièrement le fait de l'homme

    Kinetic study of volatile oil of Curcuma longa L. rhizome and Carum carvi L. fruits extracted by microwave-assisted techniques using the cryogrinding

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    peer reviewedHydrodistillation assisted by microwave (HDAM) and steam distillation assisted by microwave (SDAM) of Curcuma longa L. rhizome (CL) and Carum carvi fruits (CC) were investigated. The effect of the cryogrinding (CG) showed differences in yields and composition of volatile oils compared with classical grinding. HDAM–CG (CL: 1.20%, CC: 1.25%) and SDAM–CG (CL: 1.45%, CC: 1.75%) allowed extraction of substantial amounts of volatile oils in less time compared with HDAM (CL: 0.6%, CC: 1.00%) and SDAM (CL: 0.90%, CC: 1.00%). In addition, the major amounts of volatile oils were globally obtained during the first 5 and 10 minutes of extraction for CL and CC, respectively. A kinetic study of essential oils extraction from CL and CC was quantitatively performed. The composition of the major components and family classes present a significant variation with the extraction time. Essential oils extracted by these two methods were quantitatively (yield) and qualitatively [aromatic profile by gas chromatography (GC) and GC–mass spectrometry (GC–MS)] analyzed. There were differences, especially in the major compounds ar-turmerone (HDAM: 46.00–57.96%, HDAM–CG: 30.85–60.32%) and β-turmerone (HDAM: 14.43–16.74%, HDAM–CG: 10.46–15.77%) for CL, and limonene (HDAM: 23.61–56.97%, HDAM–CG: 38.04–43.00%) and carvone (HDAM: 36.19–64.54%, CC–CG: 53.65–56.31%) for CC

    Effect of the Extraction Technique, Heating Time and Cryogenic Grinding (N2 at -196°C) on the Composition of Cumin Seeds Volatile Oil

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    Two techniques of extraction of essential oils (Steam distillation assisted by microwave (SDAM) and hydrodistillation assisted by microwave (HDAM)) are respectively advanced steam distillation (SD) and hydrodistillation techniques (HD), in which a microwave oven is used in the extraction process. They are considered as accelerated techniques extraction performed at atmospheric pressure. The cryogrinding (CG) showed a difference on the yields and aromatic profile comparing to the sample grinding. Isolation and concentration of volatile compounds are performed by a single stage for the extraction of volatile oil from Algerian (Sahara) Cuminum cyminum seeds (CCS). The chemical composition of the essential oil of this plant as a function of extraction time was also studied. The major components and family classes showed a significant variation with the extraction time. Gas chromatography (GC), GCxGC-mass spectrometry (GCxGC-MS)] were utilised for qualitative and quantitative analysis of essential oils extracted by these two methods. The major compounds are cumin aldehyde (HDAM-CG: 20.50-53.35 %, SDAM-CG: 21.68 66.6 %), p-cymene (HDAM-CG: 14.1-37.54 %, SDAM-CG: 6.06-20.18 %), β-pinene (HDAM-CG: 4.53-14.74 %, SDAM-CG: 4.3-32.65 %) and γ-terpinene (HDAM-CG: 1.26-14.70 %, SDAM-CG: 5.13-18.23 %)
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