Tectonique moléculaire (Réseaux moléculaires non-covalents et directionnels à base de dérivés Calix[4]arènes)

La formation de réseaux moléculaires d'inclusion à l'état solide est obtenue par un phénomène d'auto-assemblage basé sur des interactions faibles et réversibles de type van der Waals entre des briques moléculaires complémentaires portant des cavités et des molécules connecteurs. La conception de ces réseaux nécessite la synthèse de tectons linéaires ou koilands à l'aide d'unités calix[4]arènes en conformation cône. Les koilands sont synthétisés par fusion de deux unités calix[4]arènes par des atomes à géométrie de coordination tétraédrique. Les réseaux moléculaires 1-D linéaires par inclusion ou koilates, sont conçus en utilisant les phénomènes de reconnaissance moléculaire à l'état cristallin. Ainsi, par inclusion d'une molécule d'hexadiyne dans les cavités de deux dimères bisilylés de p-iso-propylcalix[4]arène consécutifs, un réseau moléculaire infini est obtenu par un processus d'assemblage. Le contrôle de la directionalité des réseaux d'inclusion est important pour l'exploitation des propriétés physiques directionnelles, comme les interactions dipolaires. La formation de réseaux directionnels est guidée par la conception de koilands non-centrosymétriques soit par différentiation géométrique des cavités comme le koiland bisilylé p-allyl/p-tert-butylcalix[4]arène, soit par différentiation électronique comme le koiland monosilylé p-tert-butylcalix[4]arène, le dimère Ti/Si ou Ge/Si de p-tert-butylcalix[4]arène. Un koilate orienté est ainsi obtenu par inclusion du phénylpropyne par deux koilands p-allyl/p-tert-butylcalix[4]arène consécutifs. L'extrémité phényle est incluse côté cavité portant des groupes allyles, alors que l'extrémité propyne se loge du côté des groupes tert-butyles. La translation de ce motif dissymétrique d'interaction conduit à un réseau 1-D directionnel d'inclusion. Cependant, deux fils directionnels consécutifs disposés de façon parallèle dans la maille présentent une direction opposée. Par conséquent, la présence de centres de symétrie rend le solide non-polaire. Mais, à partir du koiland monosilylé et dans des conditions particulières de cristallisation, des réseaux directionnels disposés de façon non-centrosymétrique sont obtenus avec pour originalité, une modification géométrique de l'environnement tétraédrique autour du silicium.The construction of large inclusion molecular networks in the solid state may be reached through self-assembly process of complementary modules and ensured by weak and reversible noncovalent interactions (van der Waals forces).The formation of molecular networks is achieved through the synthesis of linear tectons named koilands using calix[4]arenes derivatives in cone conformation. Koilands were obtained upon fusion of two calix[4]arenes units by two metals with a tetrahedral coordination geometry. Infinite and linear inclusion molecular networks named koilates are formed using molecular recognition principles in the crystalline phase. Thus, an infinite 1-D molecular network was generated under self-assembly conditions based on inclusion processes of consecutive p-iso-propylcalix[4]arene koilands with hexadiyne as connector molecules.Dealing with 1-D inclusion networks, the control of directionality is crucial for the exploitation of directional physical properties such as dipolar interactions. The formation of such directional networks may be based on the design of non-centrosymmetric koilands either on geometric differentiation of the two cavities such as p-allyl/p-tert-butylcalix[4]arene doubly Si fused koiland, or on electronic differentiation such as monosilicon p-tert-butylcalix[4]arene koiland, Ti/Si or Ge/Si p-tert-butylcalix[4]arene koilands. For example, a linear directional koilate is obtained through inclusion processes of phenylpropyne connectors bridging two consecutives p-allyl/p-tert-butylcalix[4]arene koilands. Whereas the propyne moiety of the connector is included within the cavity with tert-butyl groups, the phenyl moiety penetrates the cavity bearing allyl groups. Due to the unsymmetrical nature of the assembling core, upon translation, a 1-D directional koilate is obtained. Unfortunately, the directional linear koilates are positioned in a parallel fashion but with opposite orientation, thus leading to a non-directional packing then to a non-polar solid.However, using monosilicon p-tert-butylcalix[4]arene koiland with particular crystallisation conditions, directional koilates with non-centrosymmetric packing are obtained with an original modification of the tetrahedral geometry around fusing silicon.STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF

BCSearch: fast structural fragment mining over large collections of protein structures

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Linear relationship between lateralization of the bicipital groove and humeral retroversion and its link with the biepicondylar humeral line. Anatomical study of seventy cadaveric humerus scans

International audienceIntroduction Morphological studies of the humerus have shown that the position of the bicipital groove varies with the individual and the retroversion of the humeral head. Depending on the authors, these two parameters are independent or associated. This study evaluated the relationship between the humeral head axis and its retroversion and the bicipital groove relative to the humeral biepicondylar line.Materials and methods Seventy cadaveric humeri were scanned to obtain 3D reconstructions. Views of the 3D reconstruction from above showed the bicondylar line, the bicipital groove and the humeral head on a single image. After measuring the humeral retroversion angle and the bicipital groove angle relative to the bicondylar line, we assessed the relationship between these two angles with Pearson's correlation coefficient.Results Pearson's correlation coefficient indicated a significant linear correlation between the angle of the groove and the angle of humeral retroversion based on the 70 cadaveric humeral bones (the p-value was 7.5(10) (7), the correlation coefficient was -0.5515, and the 95% confidence interval was (-0.6962; -0.3636)). Our study thus demonstrates that the less lateralized the bicipital groove is, the greater the humeral retroversion will be.Conclusion We demonstrated a linear relationship between humeral head retroversion and bicipital groove lateralization. Within our reliability interval, this relationship can be used in clinical practice to evaluate retroversion without resorting to CT of the entire humerus

Post-crystallization alteration of natural uraninites: Implications for dating, tracing, and nuclear forensics

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Determination of a new computed tomography method for measuring the glenoid version and comparing with a reference method. Radio-anatomical and retrospective study

International audiencePurpose In the literature, there are several techniques for measuring the glenoidal version of the scapula. The superiority of the scannographic measurement over the standard radiologic measures seems evident. The main problems are the evaluation and the reproducibility of these methods, which are dependent on the quality of the CT scan and the orientation of its sections. We pinpoint a simple method of the "scapular triangle", the reliability of which deserves special consideration. The aim of this study is to report a simple and reproducible computed tomography method to measure the glenoidal version.Methods Thrity-one shoulder CT scans, performed on patients attending the emergency department of the University Hospital of Dijon between January 2012 and April 2013 for shoulder trauma, were evaluated retrospectively. The CT scan must include the entire body of scapula to allow measurements to be made with both methods: the conventional method of Friedman and our new method of the "scapular triangle". Two independent operators performed inter-observer and intra-observer reproducibility. We compared both techniques with Pearson's test.Result Pearson's test showed a trend line according to a linear correlation between the two methods with a p value of 7.791(-10) and a correlation coefficient of 0.85 with the 95 % confidence interval (0.7213; 0.929).Conclusion The method of the "scapular triangle" is easily applicable on most sections of the CT scan of scapula whether or not it takes the whole body. It is more reliable and reproducible and could be used by any radiologist

BCSearch: fast structural fragment mining over large collections of protein structures

Resources to mine the large amount of protein structures available today are necessary to better understand how amino acid variations are compatible with conformation preservation, to assist protein design, engineering and, further, the development of biologic therapeutic compounds. BCSearch is a versatile service to efficiently mine large collections of protein structures. It relies on a new approach based on a Binet–Cauchy kernel that is more discriminative than the widely used root mean square deviation criterion. It has statistics independent of size even for short fragments, and is fast. The systematic mining of large collections of structures such as the complete SCOPe protein structural classification or comprehensive subsets of the Protein Data Bank can be performed in few minutes. Based on this new score, we propose four innovative applications: BCFragSearch and BCMirrorSearch, respectively, search for fragments similar and anti-similar to a query and return information on the diversity of the sequences of the hits. BCLoopSearch identifies candidate fragments of fixed size matching the flanks of a gaped structure. BCSpecificitySearch analyzes a complete protein structure and returns information about sites having few similar fragments. BCSearch is available at http://bioserv.rpbs.univ-paris-diderot.fr/services/BCSearch

Formation of U-rich mineralizing fluids through basinal brine migration within basement-hosted shear zones: A large-scale study of the fluid chemistry around the unconformity-related Cigar Lake U deposit (Saskatchewan, Canada)

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