DEVELOPPEMENT DE LA DIFFRACTION ANOMALE DISPERSIVE, APPLICATION A L'ETUDE DE STRUCTURES MODULEES INORGANIQUES ET DE MACROMOLECULES BIOLOGIQUES PDF Download
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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.
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.
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.
Author: Sander Van Smaalen
Publisher: OUP Oxford
ISBN: 0191524786
Category : Science
Languages : en
Pages : 284
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For many years it was believed that translational symmetry would be the fundamental property of crystal structures of natural and synthetic compounds. It is now recognised that many compounds crystallise without translational symmetry of their atomic structures. "Incommensurate Crystallography" gives a comprehensive account of the superspace theory for the description of crystal structures and symmetries of these incommensurately modulated crystals and incommensurate composite crystals. It thus provides the necessary background for quantitative analysis of incommensurate crystals by methods in Solid State Chemistry and Solid State Physics. The second half of "Incommensurate Crystallography" is devoted to crystallographic methods of structural analysis of incommensurate compounds. Thorough accounts are given of the diffraction by incommensurate crystals, the choice of parameters in structure refinements, and the use of superspace in analysing crystal structures. The presentation of methods of structure determination includes modern methods like the Maximum Entropy Method and Charge Flipping.
Author: Conor Wickham
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author:
Publisher:
ISBN:
Category : Physics
Languages : en
Pages : 1012
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Author: Télesphore Sime-Ngando
Publisher: Springer
ISBN: 3319399616
Category : Science
Languages : en
Pages : 422
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This book represents the first multidisciplinary scientific work on a deep volcanic maar lake in comparison with other similar temperate lakes. The syntheses of the main characteristics of Lake Pavin are, for the first time, set in a firmer footing comparative approach, encompassing regional, national, European and international aquatic science contexts. It is a unique lake because of its permanently anoxic monimolimnion, and furthermore, because of its small surface area, its substantially low human influence, and by the fact that it does not have a river inflow. The book reflects the scientific research done on the general limnology, history, origin, volcanology and geological environment as well as on the geochemistry and biogeochemical cycles. Other chapters focus on the biology and microbial ecology whereas the sedimentology and paleolimnology are also given attention. This volume will be of special interest to researchers and advanced students, primarily in the fields of limnology, biogeochemistry, and aquatic ecology.
Author: Claude Cohen-Tannoudji
Publisher: John Wiley & Sons
ISBN: 3527345558
Category : Science
Languages : en
Pages : 790
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Book Description
This new, third volume of Cohen-Tannoudji's groundbreaking textbook covers advanced topics of quantum mechanics such as uncorrelated and correlated identical particles, the quantum theory of the electromagnetic field, absorption, emission and scattering of photons by atoms, and quantum entanglement. Written in a didactically unrivalled manner, the textbook explains the fundamental concepts in seven chapters which are elaborated in accompanying complements that provide more detailed discussions, examples and applications. * Completing the success story: the third and final volume of the quantum mechanics textbook written by 1997 Nobel laureate Claude Cohen-Tannoudji and his colleagues Bernard Diu and Franck Laloë * As easily comprehensible as possible: all steps of the physical background and its mathematical representation are spelled out explicitly * Comprehensive: in addition to the fundamentals themselves, the books comes with a wealth of elaborately explained examples and applications Claude Cohen-Tannoudji was a researcher at the Kastler-Brossel laboratory of the Ecole Normale Supérieure in Paris where he also studied and received his PhD in 1962. In 1973 he became Professor of atomic and molecular physics at the Collège des France. His main research interests were optical pumping, quantum optics and atom-photon interactions. In 1997, Claude Cohen-Tannoudji, together with Steven Chu and William D. Phillips, was awarded the Nobel Prize in Physics for his research on laser cooling and trapping of neutral atoms. Bernard Diu was Professor at the Denis Diderot University (Paris VII). He was engaged in research at the Laboratory of Theoretical Physics and High Energy where his focus was on strong interactions physics and statistical mechanics. Franck Laloë was a researcher at the Kastler-Brossel laboratory of the Ecole Normale Supérieure in Paris. His first assignment was with the University of Paris VI before he was appointed to the CNRS, the French National Research Center. His research was focused on optical pumping, statistical mechanics of quantum gases, musical acoustics and the foundations of quantum mechanics.
Author: T. Aïfa
Publisher: Geological Society of London
ISBN: 1786204894
Category : Science
Languages : en
Pages : 357
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This Special Publication combines results obtained by interdisciplinary groups from numerous academic institutions working on Paleoproterozoic formations to decipher the origins of the main mineralization resources in the West African Craton (WAC) and their impacts on African economic development. Structural, geophysical, sedimentological, stratigraphical, geochemical, petrophysical and mineralogical analyses have been used to highlight the complexities involved in mineralization emplacement and its origin and evolution within the WAC. Fourteen articles contribute to new knowledge in mineral research. They show that the geodynamic evolution of the WAC is complex from one area to another: it involves subduction, collision and obduction during several deformation phases ranging from Birimian (2.3–2.0 Ga) to Pan-African (650–450 Ma) events. Various modelling techniques, when integrated, help in understanding the mechanisms of mineralization emplacement, some of which are still a matter of debate. The challenge for further studies is mitigation for sustainable development that can be appropriately used to minimize such damage.
Author:
Publisher:
ISBN:
Category : Chemistry
Languages : en
Pages : 884
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Author:
Publisher:
ISBN:
Category : French periodicals
Languages : en
Pages : 560
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