Full-profile search–match by the Rietveld method

International audienceA new search–match procedure has been developed and tested which, in contrast to previously existing methods, does not use a set of lines identified from a diffraction pattern, but an optimized Rietveld fitting on the raw data. Modern computers with multicore processors allow the routine to be fast enough to perform the entire search in a reasonable time using quite large databases of crystal structures. The search–match is done using the crystal structures for all phases and the instrumental geometry, and as such can be applied to every kind of diffraction experiment, including X-rays, thermal/time-of-flight neutrons and electrons. The methodology can also be applied to nanocrystalline samples for which peak identification may be a problem. A web interface has been developed to permit easy testing and evaluation of the procedure. The quality of the results mainly depends on the availability of the sought phase in the structure database. The method permits not only phase identification but also a rapid quantification of the phases and their gross microstructural features, provided the instrumental function is known. © 2019 Luca Lutterotti et al. Journal of Applied Crystallography published by IUCr Journals

Full-profile search–match by the Rietveld method

A new search–match procedure has been developed and tested which, in contrast to previously existing methods, does not use a set of lines identified from a diffraction pattern, but an optimized Rietveld fitting on the raw data. Modern computers with multicore processors allow the routine to be fast enough to perform the entire search in a reasonable time using quite large databases of crystal structures. The search–match is done using the crystal structures for all phases and the instrumental geometry, and as such can be applied to every kind of diffraction experiment, including X-rays, thermal/time-of-flight neutrons and electrons. The methodology can also be applied to nanocrystalline samples for which peak identification may be a problem. A web interface has been developed to permit easy testing and evaluation of the procedure. The quality of the results mainly depends on the availability of the sought phase in the structure database. The method permits not only phase identification but also a rapid quantification of the phases and their gross microstructural features, provided the instrumental function is known. © 2019 Luca Lutterotti et al. Journal of Applied Crystallography published by IUCr Journals

LIBS in a low temperature plasma for the detection of airborne asbestos

International audienceForbidden in french constructions since 1997, asbestos remains present in most of the buildings constructed before this date. Thus, during work or in case of degradation, asbestos fibres can be emitted in air. The smaller the asbestos particles, the longer they stay in suspension in air, increasing the hazard of inhaling them. The current determination of airborne asbestos presence in France follows a long and cumbersome normative protocol (NF X 43-050), with an analysis carried out on a Transmission Electron Microscope at laboratory after air filtration on-site. Such a protocol induces wasting time between the sampling and the results delayed not less than 48 hours and therefore prevents for the intervention on-site-on-time. Thus, the demand of a real-time measurement increases, even if it is only an alert technique. The PLASMIANTE project aims to develop an apparatus able, on-site and in near-real-time, to analyse the particles present in an air sample and to identify the presence of asbestos. The device will sample air and send the particles in a reactor in which they will be trapped in a low-temperature argon plasma. Among several diagnostics that will be applied directly on the particles in suspension in the plasma, Laser Induced Breakdown Spectroscopy will be used to identify the presence of asbestos in the samples. In this study, we present the first results of LIBS applied to particles of asbestos, building materials and mixtures in suspension in a low temperature plasma

Analyse combinée FluoX-caméra RVB et FluoX-DRX des gisements de latérite nickélifère de Nouvelle-Calédonie : nouvelle approche méthodique

International audienceAs part of the European SOLSA project, BRGM and CRISMAT are participating in the development of a multi-sensor expertise bench (SOLSA ID2A-ID2B). The major challenge of SOLSA is to understand the approach of a field geologist to samples in order to enable the retranscription of his knowledge in the form of intelligent algorithms. In this context, a sample prepared in three forms (powder, thin slide and raw sample) was selected in this study. It is a serpentinised harzburgite. The sample was first characterised in the laboratory (X-ray fluorescence, ICP-AES, and X-ray diffraction) and then analysed under these different preparations on SOLSA ID2B. This study showed that the field approach allows similar results to those obtained in the laboratory but with a higher profitability. By comparing the results obtained on the three types of preparation, it was shown that the influence of the sample preparation is minor on the combined FluoX-DRX results. Finally, by creating an algorithm allowing the superposition of RGB images and the spatial distribution of chemical elements (Fig 1), it was possible to improve the knowledge of substitutions within the phases present, the location of certain elements in preferential zones and the element/element and phase/element correlations.Dans le cadre du projet européen SOLSA, le BRGM et le CRISMAT, participent au développement d’un banc d’expertise multi-capteurs (SOLSA ID2A-ID2B). L’enjeu majeur de SOLSA, est d’appréhender l’approche d’un géologue de terrain sur des échantillons afin de permettre une retranscription de son savoir sous forme d’algorithmes intelligents. Dans ce contexte, un échantillon préparé sous trois formes (poudre, lame mince et échantillon brut) a été sélectionné dans cette étude. Il s’agit d’une harzburgite serpentinisée. L’échantillon a d’abord été caractérisé en laboratoire (fluorescence X, ICP-AES, et diffraction des rayons X) puis analysé sous ces différentes préparations sur SOLSA ID2B. Cette étude a permis de montrer que l’approche de terrain admet des résultats similaires aux résultats obtenus en laboratoire mais avec une rentabilité plus élevée. En comparant les résultats obtenus sur les trois types de préparation, il a été démontré que l’influence de la préparation de l’échantillon est mineure sur les résultats combinés FluoX-DRX. Enfin, par la création d’algorithme permettant la superposition d’image RVB et la distribution spatiale des éléments chimiques (Fig 1), il a été possible d’améliorer la connaissance des substitutions au sein des phases présentes, la localisation de certains éléments dans des zones préférentielles et les corrélations éléments/éléments et phases/éléments

Analyse combinée FluoX-caméra RVB et FluoX-DRX des gisements de latérite nickélifère de Nouvelle-Calédonie : nouvelle approche méthodique

International audienceAs part of the European SOLSA project, BRGM and CRISMAT are participating in the development of a multi-sensor expertise bench (SOLSA ID2A-ID2B). The major challenge of SOLSA is to understand the approach of a field geologist to samples in order to enable the retranscription of his knowledge in the form of intelligent algorithms. In this context, a sample prepared in three forms (powder, thin slide and raw sample) was selected in this study. It is a serpentinised harzburgite. The sample was first characterised in the laboratory (X-ray fluorescence, ICP-AES, and X-ray diffraction) and then analysed under these different preparations on SOLSA ID2B. This study showed that the field approach allows similar results to those obtained in the laboratory but with a higher profitability. By comparing the results obtained on the three types of preparation, it was shown that the influence of the sample preparation is minor on the combined FluoX-DRX results. Finally, by creating an algorithm allowing the superposition of RGB images and the spatial distribution of chemical elements (Fig 1), it was possible to improve the knowledge of substitutions within the phases present, the location of certain elements in preferential zones and the element/element and phase/element correlations.Dans le cadre du projet européen SOLSA, le BRGM et le CRISMAT, participent au développement d’un banc d’expertise multi-capteurs (SOLSA ID2A-ID2B). L’enjeu majeur de SOLSA, est d’appréhender l’approche d’un géologue de terrain sur des échantillons afin de permettre une retranscription de son savoir sous forme d’algorithmes intelligents. Dans ce contexte, un échantillon préparé sous trois formes (poudre, lame mince et échantillon brut) a été sélectionné dans cette étude. Il s’agit d’une harzburgite serpentinisée. L’échantillon a d’abord été caractérisé en laboratoire (fluorescence X, ICP-AES, et diffraction des rayons X) puis analysé sous ces différentes préparations sur SOLSA ID2B. Cette étude a permis de montrer que l’approche de terrain admet des résultats similaires aux résultats obtenus en laboratoire mais avec une rentabilité plus élevée. En comparant les résultats obtenus sur les trois types de préparation, il a été démontré que l’influence de la préparation de l’échantillon est mineure sur les résultats combinés FluoX-DRX. Enfin, par la création d’algorithme permettant la superposition d’image RVB et la distribution spatiale des éléments chimiques (Fig 1), il a été possible d’améliorer la connaissance des substitutions au sein des phases présentes, la localisation de certains éléments dans des zones préférentielles et les corrélations éléments/éléments et phases/éléments

Prevalence of familial hypercholesterolaemia in patients presenting with premature acute coronary syndrome

International audienceBackground: Familial hypercholesterolaemia (FH) is responsible for severe hypercholesterolaemia and premature cardiovascular morbidity and mortality. The first clinical event is typically an acute coronary syndrome. Unfortunately, FH is largely underdiagnosed in the general population. Aims: To assess the prevalence of clinical FH among patients with premature (aged ≤ 50 years) acute myocardial infarction (MI) and compare it with FH prevalence in a control population. Methods: We reviewed in our database all patients with premature MI (aged ≤ 50 years) referred to Ambroise Paré Hospital from 2014 to 2018. FH prevalence was estimated via the Dutch Lipid Clinic Network score, based on personal and family history of premature cardiovascular disease and low-density lipoprotein cholesterol concentrations. FH was “possible” with a score between 3 and 5 points, “probable” with a score between 6 and 8 and “definite” with a score above 8. FH prevalence in young patients with MI was then compared with FH prevalence in a general population of the same age from the CARVAR 92 prospective cohort. Results: Of the 457 patients with premature MI, 29 (6%) had “probable” or “definite” FH. In the CARVAR 92 cohort, 16 (0.16%) of 9900 subjects aged ≤ 50 years had “probable” or “definite” FH. FH prevalence was 39 times greater among patients with premature MI than in the control population (P 30-fold more common in patients referred for premature MI than in the general population; this highlights the need for FH screening after a first MI to enhance lipid-lowering therapy and allow early identification of family members