Download or read book DESORPTION LASER ET SPECTROMETRIE DE MASSE PAR TEMPS DE VOL ASPECTS FONDAMENTAUX APPLICATIONS written by PIERRE.. CHAURAND and published by . This book was released on 1994 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: LA TECHNIQUE DE SPECTROMETRIE DE MASSE PAR TEMPS DE VOL EST ACTUELLEMENT UN OUTIL TRES PERFORMANT POUR L'ANALYSE D'IONS MOLECULAIRES DE MASSES ELEVEES (100 000 U ET PLUS). LE PASSAGE EN PHASE GAZEUSE ET L'IONISATION DE TELLES MOLECULES SONT DEVENUS POSSIBLES GRACE A LA TECHNIQUE DE PRODUCTION DES IONS APPELEE MALDI (MATRIX ASSISTED LASER DESORPTION IONIZATION). ELLE CONSISTE A MELANGER LES MACROMOLECULES AVEC UNE MATRICE ORGANIQUE AYANT POUR PROPRIETE D'ABSORBER A LA LONGUEUR D'ONDE DU LASER UTILISE. UN DEPOT SOLIDE DU MELANGE EST ENSUITE SOUMIS A DES TIRS LASER PULSES QUI EJECTENT LES MACROMOLECULES INTACTES EN GRAND NOMBRE. DES ETUDES FONDAMENTALES SUR LES PROCESSUS DE DESORPTION-IONISATION ONT ETE EFFECTUEES. NOUS AVONS MIS EN EVIDENCE QUE LE CHOIX DE LA MATRICE INFLUENCE BEAUCOUP LE TYPE D'IONS FORMES (MULTIMERES OU MULTICHARGES) ET LEUR METASTABILITE. DES IRRADIANCES LASER FAIBLES, DE QUELQUE 10#6 W/CM#2, SONT NECESSAIRES. DANS CES CONDITIONS, NOUS MONTRONS QUE LES RESOLUTIONS EN MASSE SONT OPTIMALES ET QUE LA PRECISION RELATIVE OBTENUE SUR LES VALEURS DES MASSES MOLECULAIRES ATTEINT QUELQUE 10#-#4 (SOIT 5 U POUR DES MASSES DE L'ORDRE DE 30 000 U). NOUS AVONS EGALEMENT MIS EN EVIDENCE QUE L'ANGLE D'EMISSION DES IONS MOLECULAIRES EN MALDI DEPEND DE L'ANGLE D'INCIDENCE DE LA LUMIERE LASER. AU COURS DES PROCESSUS D'EJECTION, LES IONS MOLECULAIRES SONT EMIS DANS LA DIRECTION INVERSE DE LA LUMIERE LASER. CET EFFET EST PARTICULIEREMENT IMPORTANT POUR LA CONCEPTION DE L'ESPACE ACCELERATEUR DES IONS MOLECULAIRES DANS LES SPECTROMETRES DE MASSE A TEMPS DE VOL. LES PROBLEMES LIES A LA DETECTION DE CES IONS MOLECULAIRES DE HAUTES MASSES ONT AUSSI ETE ETUDIES EN DETAIL. UNE VALEUR SEUIL EN VITESSE D'IMPACT DE L'ORDRE DE 0,5.10#4M/S A PU ETRE DETERMINEE POUR L'EMISSION ELECTRONIQUE. ENFIN, DES EXEMPLES D'APPLICATIONS SUR L'IDENTIFICATION EN MASSE DE MOLECULES DE C#6#0 ET DE MOLECULES DERIVEES (PAR EXEMPLE C#6#0F#X) SONT PRESENTES ET DIFFERENTES TECHNIQUES DE PRODUCTION DES IONS SONT COMPAREES

Download or read book Caract risation du couplage des techniques de d sorption laser ionisation laser et spectrom trie de masse temps de vol written by Michael Ziskind and published by . This book was released on 2010 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ce mémoire d'HDR synthétise les travaux effectués dans le cadre de deux projets développés au sein de notre équipe au laboratoire PhLAM : - l'étude des processus hétérogènes d'intérêt environnemental et biologique à la surface et dans le volume de la glace. - l'étude des hydrocarbures aromatiques polycycliques (HAP) adsorbés à la surface des particules de suies émises lors de la combustion incomplète de combustible fossile. Le procédé expérimental utilisé pour mener à bien ces projets est basé sur le couplage des techniques de désorption laser, de photo-ionisation et de spectrométrie de masse. Pour exploiter de manière optimale le potentiel analytique et technologique de ce dispositif, il est nécessaire d'en comprendre les mécanismes. Pour ce faire, nous avons opté pour une stratégie d'études paramétriques, en jouant sur divers éléments de l'expérience (longueurs d'onde, énergies, nature des substrats...). En utilisant cette approche le couplage entre les processus de désorption et d'ionisation a pu être décrit à travers la variation de l'énergie interne des molécules éjectées suite à l'interaction laser-matière. Le caractère parfaitement résonnant du processus de désorption, lié à l’excitation des modes de stretching O-H et C-H sur des échantillons de glace et de HAP purs respectivement, a également été démontré. L'adaptation de ces travaux à des échantillons binaires a permis de mettre pour la première fois en évidence deux régimes de désorption, le 1er correspondant à la désorption exclusive d'un des deux composés de l'échantillon irradié, le 2nd correspondant au régime classique de co-désorption, associé à la présence d'agrégats hydratés dans le cas de solution aqueuse gelée. Les applications liées à cette technique seront discutées, en distinguant celles associées au régime de désorption sélective (mesure de profils de diffusion de gaz traces dans la glace, analyse d'échantillons complexes...) et au régime de co-désorption (MALDI IR, production d'agrégats d'intérêt atmosphérique ou biologique). L'étude des HAP adsorbés à la surface des suies selon le stade de la combustion et la nature du carburant sera présentée dans une dernière partie. Ces travaux, initiées sur des flammes d'acétylène, puis de Diesel, se poursuivent aujourd'hui sur des flammes de méthane basse pression et démontrent tout le potentiel de la technique pour explorer les mécanismes de formation des suies.

Download or read book Government Reports Announcements Index written by and published by . This book was released on 1996 with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book ETUDE DES MECANISMES DE DESORPTION IONISATION EN SPECTROMETRIE DE MASSE A TEMPS DE VOL APPLICATION A L ANALYSE DE PESTICIDES written by SOPHIE.. BOURCIER and published by . This book was released on 1996 with total page 307 pages. Available in PDF, EPUB and Kindle. Book excerpt: DANS CE TRAVAIL, NOUS AVONS EU UN DOUBLE OBJECTIF : (I) TESTER LES TECHNIQUES DE DESORPTION-IONISATION COUPLEES A UN TEMPS DE VOL COMME METHODE D'ANALYSE POUR ETUDIER QUELQUES FAMILLES DE PESTICIDES, (II) APPORTER UNE CONTRIBUTION A LA COMPREHENSION DES MECANISMES D'IONISATION PROVOQUES PAR IMPACT D'UN FAISCEAU DE PARTICULES INCIDENTES SUR UN ECHANTILLON SOLIDE. DES SPECTRES DE MASSE DE PESTICIDES ONT ETE REALISES PAR DESORPTION-IONISATION (DI) PAR DES IONS RAPIDES (PD-MS) ET PAR PHOTONS (LD-MS) ET COMPARES POUR EVALUER LA VALEUR INFORMATIVE DE CHAQUE TECHNIQUE. IL S'AVERE, QUE CE SONT LES SPECTRES DE PD-MS QUI PRESENTENT LE PLUS GRAND NOMBRE D'IONS ET PERMETTENT D'IDENTIFIER ET DE DIFFERENCIER LES FAMILLES DE PESTICIDES. UN MELANGE D'IONS MOLECULAIRES QUI SONT, SOIT DES MOLECULES PROTONEES, SOIT DES IONS RADICAUX MOLECULAIRES, EST SOUVENT OBSERVE. AFIN D'OBTENIR DES INFORMATIONS SUR LA QUANTITE D'ENERGIE TRANSMISE AUX ECHANTILLONS DURANT LE PROCESSUS DE DI, NOUS AVONS ETABLI LA FILIATION ENTRE UN ION FRAGMENT ET UN ION MOLECULAIRE PAR COMPARAISON DES SPECTRES DE PD-MS A CEUX OBTENUS PAR LES METHODES QUI ENGENDRENT SELECTIVEMENT MH#+ (IONISATION CHIMIQUE, NH#3, CH#4) ET M#+#. (IMPACT ELECTRONIQUE). NOUS AVONS TRACE, GRACE A LA THERMOCHIMIE, LES DIAGRAMMES D'ENERGIE POTENTIELLE ASSOCIES A CHAQUE FRAGMENTATION OBSERVEE. LES INFORMATIONS OBTENUES NOUS ONT PERMIS D'APPROCHER LES DISTRIBUTIONS EN ENERGIE INTERNE TRANSMISES AU COURS DE LA FORMATION DES IONS PAR PD-MS. L'ENSEMBLE DE NOS RESULTATS PERMET D'AFFIRMER QUE LA PD-MS EST UNE TECHNIQUE PARTICULIEREMENT INTERESSANTE POUR L'ANALYSE DES COMPOSES ETUDIES PUISQU'ELLE APPORTE DE MULTIPLES INFORMATIONS : CELLES OBTENUES HABITUELLEMENT PAR LES TECHNIQUES D'IONISATION CLASSIQUES (IE ET IC) AINSI QUE DE NOUVELLES PROVENANT D'IONS DONT LA FORMATION REQUIERT UNE FORTE ENERGIE.

Download or read book HIE ISOLDE the Technical Options written by European Organization for Nuclear Research and published by . This book was released on 2006 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Radioactive Aerosols written by Constantin Papastefanou and published by Elsevier. This book was released on 2011-07-28 with total page 187 pages. Available in PDF, EPUB and Kindle. Book excerpt: Whenever radioactivity is released to the atmosphere, for example by the detonation of nuclear weapons or the testing of nuclear weapons or from nuclear reactor accidents that fraction of it which remains airborne for more than a few hours is liable to be attached to aerosol particles. The resulting radioactive aerosols are carried by atmospheric mixing processes until they settle out or are scavenged by precipitation. The radiation exposure pathway of maximum concern to humans is by inhalation of aerosols and their deposition in the respiratory tract. In this context, it is important to note that radioactive aerosols are commonly of natural origin alos. In particular, the associated radionuclides can be of natural terrestrial origin, such as the decay products of radon gas, or they can e cosmogenic, such as beryllium-7. The exposure of miners of uranium and other ores and minerals to radon and its aerosol-borne decay products is of major significance. The book describes the formation of aerosols, their aerodynamic size distribution, their atmospheric residence time, their sampling and measurement, the range of radioactive aerosols found and studied thus far, including man-made nuclides and radon decay products and their interaction with man, including deposition in the lung and subsequent health effects. - Advanced level science handbook for researchers, scientists and academics - Covers all aspects of radiation exposure in humans, including subsequent health implications - Presents the latest findings and analysis in this highly topical area

Download or read book Biotechnology of Extremophiles written by Pabulo H Rampelotto and published by Springer. This book was released on 2016-04-27 with total page 726 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aimed at research scientists and biotechnologists, this book is an essential reading for those working with extremophiles and their potential biotechnological application. Here, we provide a comprehensive and reliable source of information on the recent advances and challenges in different aspects of the theme. Written in an accessible language, the book is also a recommended as reference text for anyone interested in this thriving field of research. Over the last decades, the study of extremophiles has provided ground breaking discoveries that challenge our understanding of biochemistry and molecular biology. In the applied side, extremophiles and their enzymes have spawned a multibillion dollar biotechnology industry, with applications spanning biomedical, pharmaceutical, industrial, environmental, and agricultural sectors. Taq DNA polymerase (which was isolated from Thermus aquaticus from a geothermal spring in Yellowstone National Park) is the most well-known example of the potential biotechnological application of extremophiles and their biomolecules. Indeed, the application of extremophiles and their biologically active compounds has opened a new era in biotechnology. However, despite the latest advances, we are just in the beginning of exploring the biotechnological potentials of extremophiles.

Download or read book The Dead Sea written by Tina M. Niemi and published by Oxford University Press, USA. This book was released on 1997 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt: Located 400 meters below sea level, at the tectonically active irregular boundary between the Mediterranean and Arabic plates, the Dead Sea is the site of many interesting phenomena. It provides a modern analog for ancient pull-apart basins and allows researchers to examine the process of evaporite deposition from deep water. It also offers insight into the adaptive ability of the life form living in the hypersaline brine. This book, based on a conference held in Tel Aviv in December 1993, focuses on the geophysics, geochemistry, hydrology, and climatology of the Dead Sea region.

Download or read book Beam Instrumentation and Diagnostics written by Peter Strehl and published by Springer Science & Business Media. This book was released on 2006-06-18 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book summarizes the experience of many years of teamwork with my group, the beam diagnostics group of GSI. For a long time the group was also responsible for operating the machines and application programming. In my opinion, this connection was very e?cient: ?rst, because a beam diagnostic system has to place powerful tools at the operators’ disposal; second, because data evaluation and presentation of results for machine operation demand application programs which can be handled not only by skilled experts. On the other hand, accelerator developments and improvements as well as commissioning of new machines by specialists require more complex measu- ments than those for routine machine operation. A modern beam diagnostic system, including the software tools, has to cover these demands, too. Therefore, this book should motivate physicists, constructors, electronic engineers, and computer experts to work together during the design and daily use of a beam diagnostic system. This book aims to give them ideas and tools for their work. I would not have been able to write this book without a good education in physics and many discussions with competent leaders, mentors, and c- leagues. After working about 40 years in teams on accelerators, there are so many people I have to thank that it is impossible to mention them all by name here.

Download or read book Lecture Notes on Beam Instrumentation and Diagnostics written by Peter Forck and published by . This book was released on 2015-01-10 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lecture Notes on Beam Instrumentation and DiagnosticsBy Peter Forck

Download or read book Radiation Protection Activities written by United States. Environmental Protection Agency. Office of Radiation Programs and published by . This book was released on 1976 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Archaea written by Frank T. Robb and published by CSHL Press. This book was released on 1995 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rickettsial Diseases written by Didier Raoult and published by CRC Press. This book was released on 2007-04-26 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: The only available reference to comprehensively discuss the common and unusual types of rickettsiosis in over twenty years, this book will offer the reader a full review on the bacteriology, transmission, and pathophysiology of these conditions. Written from experts in the field from Europe, USA, Africa, and Asia, specialists analyze specific patho

Download or read book Physical Properties of Amorphous Materials written by David Adler and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Institute for Amorphous Studies was founded in 1982 as the international center for the investigation of amorphous mate rials. It has since played an important role in promoting the und er standing of disordered matter in general. An Institute lecture series on "Fundamentals of Amorphous Materials and Devices" was held during 1982-83 with distinguished speakers from universities and industry. These events were free and open to the public ,and were attended by many representatives of the scientific community. The lectures themselves were highly successful inasmuch as they provided not only formal instruction but also an opportunity for vigorous and stimulating debate. That last element could not be captured within the pages of a book I but the lectures concentrated on the latest advances in the field I which is why their essential contents are he re reproduced in collective form. Together they constitute an interdisciplinary status report of the field. The speakers brought many different viewpoints and a variety of back ground experiences io bear on the problems involved I but though language and conventions vary I the essential unity of the concerns is very clear I as indeed are the ultimate benefits of the many-sided approach.

Download or read book The Baltic Sea written by A. Voipio and published by Elsevier. This book was released on 1981-01-01 with total page 401 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Baltic Sea

Download or read book Basic Radiation Protection Criteria written by and published by . This book was released on 1971 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rickettsiology written by Karim E. Hechemy and published by . This book was released on 2003 with total page 800 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rickettsial diseases, which include typhus, spotted fever, trench fever and Q fever, are very serious infectious diseases. Rickettsiae organisms also are of interest to researchers because they have been used as bioweapons, and can serve as agents for bioterrorism. In addition, they are biologically very successful organisms despite their relatively small genome. The papers in this volume are taken from the International Conference on Rickettsiae and Rickettsial Diseases, held in Ljubljana in 2002. They include state-of-the-art discussions of functional genomics, proteomics, epidemiology, ecology and clinical and diagnostic medicine.