DEVELOPPEMENT DE LA DIFFRACTION ANOMALE DISPERSIVE, APPLICATION A L'ETUDE DE STRUCTURES MODULEES INORGANIQUES ET DE MACROMOLECULES BIOLOGIQUES

DEVELOPPEMENT DE LA DIFFRACTION ANOMALE DISPERSIVE, APPLICATION A L'ETUDE DE STRUCTURES MODULEES INORGANIQUES ET DE MACROMOLECULES BIOLOGIQUES PDF Author: VINCENT.. FAVRE NICOLIN
Publisher:
ISBN:
Category :
Languages : fr
Pages : 235

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LA DIFFRACTION DES RAYONS X A ETE DEVELOPPEE DEPUIS PRES D'UN SIECLE POUR LA DETERMINATION DE STRUCTURES CRISTALLOGRAPHIQUES. MAIS LA DETERMINATION DES STRUCTURES LES PLUS COMPLEXES (PROTEINES, STRUCTURES INCOMMENSURABLES) NECESSITE L'UTILISATION DE LA DIFFRACTION ANOMALE, I.E. LA MESURE DES INTENSITES DE DIFFRACTION A PLUSIEURS LONGUEURS D'ONDE AU VOISINAGE DU SEUIL D'ABSORPTION D'UN ELEMENT DU CRISTAL. CETTE TECHNIQUE PERMET D'OBTENIR UNE INFORMATION SUR LA PHASE DU FACTEUR DE STRUCTURE, AINSI QUE SUR LES POSITIONS DES ATOMES ANOMAUX. DANS CETTE THESE, NOUS PRESENTONS LA DIFFRACTION ANOMALE DISPERSIVE (DAD), QUI PERMET DE MESURER SIMULTANEMENT LES INTENSITES DIFFRACTEES A PLUSIEURS LONGUEURS D'ONDE, POUR DE NOMBREUSES REFLEXIONS. NOUS PRESENTONS DEUX MODES DE COLLECTE, CONTINU (DDAFS-DISPERSIVE DIFFRACTION ANOMALOUS FINE STRUCTURE), ET DISCRET (SMAD-SIMULTANEOUS MULTIWAVELENGTH ANOMALOUS DIFFRACTION). NOUS AVONS DEVELOPPE UNE PROCEDURE ET UN PROGRAMME (DAD) POUR L'ANALYSE QUANTITATIVE DES IMAGES DE DIFFRACTION DISPERSIVE. CE PROGRAMME PERMET EGALEMENT L'ANALYSE D'IMAGES DE DIFFRACTION MONOCHROMATIQUE PRESENTANT DES REFLEXIONS SATELLITES PROCHES DES PICS PRINCIPAUX. NOUS PRESENTONS LES DEUX PREMIERES EXPERIENCES QUANTITATIVES DE DIFFRACTION DISPERSIVE SUR DES CRISTAUX BIOLOGIQUES. NOS RESULTATS MONTRENT QUE LA DETERMINATION DE STRUCTURE PAR LA METHODE SMAD EST POSSIBLE. DES AMELIORATIONS AUX PROTOCOLES DE COLLECTE ET D'ANALYSE SONT ENCORE NECESSAIRES POUR CES CRISTAUX. UNE PARTIE IMPORTANTE DE CETTE THESE A ETE CONSACREE A L'ETUDE DE (TASE 4) 2I : CE CRISTAL QUASI-1D PRESENTE UNE TRANSITION DE PEIERLS, LA CONDENSATION DES ATOMES DE TANTALE ETANT RECHERCHEE DEPUIS 15 ANS. NOTRE ETUDE A D'ABORD CARACTERISE LA STRUCTURE EN DOMAINES DE CE MATERIAU, ET LA DIFFRACTION ANOMALE A MIS EN EVIDENCE DE MANIERE SPECIFIQUE LA TETRAMERISATION DES ATOMES DE TANTALE, ACCOMPAGNANT LA MODULATION ACOUSTIQUE DEJA CONNUE.

DEVELOPPEMENT DE LA DIFFRACTION ANOMALE DISPERSIVE, APPLICATION A L'ETUDE DE STRUCTURES MODULEES INORGANIQUES ET DE MACROMOLECULES BIOLOGIQUES

DEVELOPPEMENT DE LA DIFFRACTION ANOMALE DISPERSIVE, APPLICATION A L'ETUDE DE STRUCTURES MODULEES INORGANIQUES ET DE MACROMOLECULES BIOLOGIQUES PDF Author: VINCENT.. FAVRE NICOLIN
Publisher:
ISBN:
Category :
Languages : fr
Pages : 235

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Book Description
LA DIFFRACTION DES RAYONS X A ETE DEVELOPPEE DEPUIS PRES D'UN SIECLE POUR LA DETERMINATION DE STRUCTURES CRISTALLOGRAPHIQUES. MAIS LA DETERMINATION DES STRUCTURES LES PLUS COMPLEXES (PROTEINES, STRUCTURES INCOMMENSURABLES) NECESSITE L'UTILISATION DE LA DIFFRACTION ANOMALE, I.E. LA MESURE DES INTENSITES DE DIFFRACTION A PLUSIEURS LONGUEURS D'ONDE AU VOISINAGE DU SEUIL D'ABSORPTION D'UN ELEMENT DU CRISTAL. CETTE TECHNIQUE PERMET D'OBTENIR UNE INFORMATION SUR LA PHASE DU FACTEUR DE STRUCTURE, AINSI QUE SUR LES POSITIONS DES ATOMES ANOMAUX. DANS CETTE THESE, NOUS PRESENTONS LA DIFFRACTION ANOMALE DISPERSIVE (DAD), QUI PERMET DE MESURER SIMULTANEMENT LES INTENSITES DIFFRACTEES A PLUSIEURS LONGUEURS D'ONDE, POUR DE NOMBREUSES REFLEXIONS. NOUS PRESENTONS DEUX MODES DE COLLECTE, CONTINU (DDAFS-DISPERSIVE DIFFRACTION ANOMALOUS FINE STRUCTURE), ET DISCRET (SMAD-SIMULTANEOUS MULTIWAVELENGTH ANOMALOUS DIFFRACTION). NOUS AVONS DEVELOPPE UNE PROCEDURE ET UN PROGRAMME (DAD) POUR L'ANALYSE QUANTITATIVE DES IMAGES DE DIFFRACTION DISPERSIVE. CE PROGRAMME PERMET EGALEMENT L'ANALYSE D'IMAGES DE DIFFRACTION MONOCHROMATIQUE PRESENTANT DES REFLEXIONS SATELLITES PROCHES DES PICS PRINCIPAUX. NOUS PRESENTONS LES DEUX PREMIERES EXPERIENCES QUANTITATIVES DE DIFFRACTION DISPERSIVE SUR DES CRISTAUX BIOLOGIQUES. NOS RESULTATS MONTRENT QUE LA DETERMINATION DE STRUCTURE PAR LA METHODE SMAD EST POSSIBLE. DES AMELIORATIONS AUX PROTOCOLES DE COLLECTE ET D'ANALYSE SONT ENCORE NECESSAIRES POUR CES CRISTAUX. UNE PARTIE IMPORTANTE DE CETTE THESE A ETE CONSACREE A L'ETUDE DE (TASE 4) 2I : CE CRISTAL QUASI-1D PRESENTE UNE TRANSITION DE PEIERLS, LA CONDENSATION DES ATOMES DE TANTALE ETANT RECHERCHEE DEPUIS 15 ANS. NOTRE ETUDE A D'ABORD CARACTERISE LA STRUCTURE EN DOMAINES DE CE MATERIAU, ET LA DIFFRACTION ANOMALE A MIS EN EVIDENCE DE MANIERE SPECIFIQUE LA TETRAMERISATION DES ATOMES DE TANTALE, ACCOMPAGNANT LA MODULATION ACOUSTIQUE DEJA CONNUE.

Développement de la diffraction anomale dispersive

Développement de la diffraction anomale dispersive PDF Author: Vincent Favre-Nicolin
Publisher:
ISBN:
Category :
Languages : fr
Pages : 0

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Book Description
La diffraction des rayons x a ete developpee depuis pres d'un siecle pour la determination de structures cristallographiques. Mais la determination des structures les plus complexes (proteines, structures incommensurables) necessite l'utilisation de la diffraction anomale, i.e. La mesure des intensites de diffraction a plusieurs longueurs d'onde au voisinage du seuil d'absorption d'un element du cristal. Cette technique permet d'obtenir une information sur la phase du facteur de structure, ainsi que sur les positions des atomes anomaux. Dans cette these, nous presentons la diffraction anomale dispersive (dad), qui permet de mesurer simultanement les intensites diffractees a plusieurs longueurs d'onde, pour de nombreuses reflexions. Nous presentons deux modes de collecte, continu (ddafs-dispersive diffraction anomalous fine structure), et discret (smad-simultaneous multiwavelength anomalous diffraction). Nous avons developpe une procedure et un programme (dad) pour l'analyse quantitative des images de diffraction dispersive. Ce programme permet egalement l'analyse d'images de diffraction monochromatique presentant des reflexions satellites proches des pics principaux. Nous presentons les deux premieres experiences quantitatives de diffraction dispersive sur des cristaux biologiques. Nos resultats montrent que la determination de structure par la methode smad est possible. Des ameliorations aux protocoles de collecte et d'analyse sont encore necessaires pour ces cristaux. Une partie importante de cette these a ete consacree a l'etude de (tase 4) 2i : ce cristal quasi-1d presente une transition de peierls, la condensation des atomes de tantale etant recherchee depuis 15 ans. Notre etude a d'abord caracterise la structure en domaines de ce materiau, et la diffraction anomale a mis en evidence de maniere specifique la tetramerisation des atomes de tantale, accompagnant la modulation acoustique deja connue.

Incommensurate Crystallography

Incommensurate Crystallography PDF Author: Sander van Smaalen
Publisher: Oxford University Press, USA
ISBN: 0198570821
Category : Science
Languages : en
Pages : 283

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Book Description
This book fully describes the structures and symmetries of incommensurately modulated crystals and composite crystals. It provides a complete presentation of crystallographic methods of structural analysis in incommensurate crystals, providing the necessary background for a skilled application of superspace methods to aperiodic crystals.

Determination des Structures 3D des Macromolecules Biologiques par Diffraction X. Partie 1

Determination des Structures 3D des Macromolecules Biologiques par Diffraction X. Partie 1 PDF Author:
Publisher: Ed. Techniques Ingénieur
ISBN:
Category :
Languages : fr
Pages : 12

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Determination des Structures 3D des Macromolecules Biologiques par Diffraction X. Partie 2

Determination des Structures 3D des Macromolecules Biologiques par Diffraction X. Partie 2 PDF Author:
Publisher: Ed. Techniques Ingénieur
ISBN:
Category :
Languages : fr
Pages : 19

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Book Description


N-Heterocyclic Carbenes

N-Heterocyclic Carbenes PDF Author: Silvia Diez-Gonzalez
Publisher: Royal Society of Chemistry
ISBN: 1782626816
Category : Science
Languages : en
Pages : 637

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Book Description
In less than 20 years N-heterocyclic carbenes (NHCs) have become well-established ancillary ligands for the preparation of transition metal-based catalysts. This is mainly due to the fact that NHCs tend to bind strongly to metal centres, avoiding the need of excess ligand in catalytic reactions. Also, NHC‒metal complexes are often insensitive to air and moisture, and have proven remarkably resistant to oxidation. This book showcases the wide variety of applications of NHCs in different chemistry fields beyond being simple phosphine mimics. This second edition has been updated throughout, and now includes a new chapter on NHC‒main group element complexes. It covers the synthesis of NHC ligands and their corresponding metal complexes, as well as their bonding and stereoelectronic properties and applications in catalysis. This is complemented by related topics such as organocatalysis and biologically active complexes. Written for organic and inorganic chemists, this book is ideal for postgraduates, researchers and industrialists.

Recent Research on Geomorphology, Sedimentology, Marine Geosciences and Geochemistry

Recent Research on Geomorphology, Sedimentology, Marine Geosciences and Geochemistry PDF Author: Attila Çiner
Publisher: Springer Nature
ISBN: 3030725472
Category : Science
Languages : en
Pages : 373

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Book Description
This edited book is based on the papers accepted for presentation during the 2nd Springer Conference of the Arabian Journal of Geosciences (CAJG-2), Tunisia, in 2019. Major subjects treated in the book include geomorphology, sedimentology, and geochemistry. The book presents an updated unique view in conjugating field studies and modeling to better quantify the process-product binomial unusual in geosciences. In the geomorphology section, 24 papers deal with topics related to fault slip and incision rates, soil science, landslides and debris flows, coastal processes, and geoarcheology, and geoheritage. Under the sedimentology section, 34 papers including stratigraphy, and environmental, tectonic, and diagenetic processes, together with evolutionary, biostratigraphic, and paleo-environmental significance of paleontology are presented. Additionally, this section also contains papers on marine geosciences, from molecular proxies related to climate to geophysical surveys. Last but not least, the third section on geochemistry is composed of 26 papers that are focused on sedimentary geochemistry and mineralogical characterization, magmatic and metamorphic processes and products, and the origin and exploration of mineral deposits. This book resumes the current situation related to the abovementioned topics mainly in the Mediterranean realm. The volume book is of interest to all researchers, practitioners, and students in the fields of geomorphology, sedimentology, and geochemistry, as well as those engaged in environmental geosciences, soil science, stratigraphy and paleontology, geoarcheology and geoheritage, marine geosciences, petrology, metallogenesis, and mineral deposits.

Phosphorus Compounds

Phosphorus Compounds PDF Author: Maurizio Peruzzini
Publisher: Springer Science & Business Media
ISBN: 9048138175
Category : Science
Languages : en
Pages : 477

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Book Description
Each chapter of Phosphorus Compounds: Advanced Tools in Catalysis and Material Sciences have been carefully selected by the editors in order to represent a state-of-the-art overview of how phosphorus chemistry can provide solutions in various fields of applications. The editors have assembled an international array of world-renowned scientists and each chapter is written by experts in the fields of synthetic chemistry, homogeneous catalysis, dendrimers, theoretical calculations, materials science, and medicinal chemistry with a special focus on the chemistry of phosphorus compounds. Phosphorus Compounds: Advanced Tools in Catalysis and Material Sciences is of interest to a general readership ranging from advanced university course students to experts in academia and industry.

Terra 2008

Terra 2008 PDF Author: Leslie Rainer
Publisher: Getty Publications
ISBN: 1606060430
Category : Architecture
Languages : fr
Pages : 438

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Book Description
Earthen architecture constitutes one of the most diverse forms of cultural heritage and one of the most challenging to preserve. It dates from all periods and is found on all continents but is particularly prevalent in Africa, where it has been a building tradition for centuries. Sites range from ancestral cities in Mali to the palaces of Abomey in Benin, from monuments and mosques in Iran and Buddhist temples on the Silk Road to Spanish missions in California. This volume's sixty-four papers address such themes as earthen architecture in Mali, the conservation of living sites, local knowledge systems and intangible aspects, seismic and other natural forces, the conservation and management of archaeological sites, research advances, and training.

Metallic Magnetism

Metallic Magnetism PDF Author: I. A. Campbell
Publisher: Springer
ISBN:
Category : Science
Languages : en
Pages : 252

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Book Description