Author: Abdelkader Anakkar
Publisher:
ISBN:
Category :
Languages : fr
Pages : 206
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Book Description
Un développement à l'ordre trois en fonction de la température et de la pression de la différence d'énergie de Gibbs entre deux phases successives est proposé pour rendre compte et prévoir les diagrammes de phase pression-température de cristaux liquides présentant des phénomènes de double rentrance. Pour l'étude expérimentale de ces comportements originaux, parmi les différentes méthodes d'analyse des transitions de phase des mésogènes sous pression, seule la méthode piézothermique convient. Elle consiste à mesurer la chaleur dégagée ou absorbée à la suite d'une variation de pression par un échantillon enfermé dans une cellule haute pression dans des conditions isothermes. Un nouveau microcalorimètre à flux thermique à couches composites, utilisant de faibles quantités de produit et fonctionnant entre -100°C et +300°C pour des pressions allant jusqu'à 7000 bars a été mis au point. Les performances du nouveau montage ont été déterminées. L'étude sur 10 mm3 d'un cristal liquide, p-octylbenzoate de p-cyanobenzoyloxyphényle, présentant une transition nématique rentrant - smectique Ad a été entreprise pour deux isothermes. Les courbes donnant le coefficient de dilatation thermique isobare en fonction de la pression montrent une nette anomalie à la transition qui diminue lorsque la température augmente. Bien que l'analyse enthalpique différentielle ne détecte pas cette transformation, les études piézothermiques montrent que cette transition n'est pas purement du second ordre, mais peut être qualifiée de très faiblement du premier ordre. La portion du diagramme de phase Pression-Température correspondant à cette transition a été déterminée.
Author: Hassan Allouchi
Publisher:
ISBN:
Category :
Languages : fr
Pages : 175
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Book Description
AFIN DE CORRELER L'ORGANISATION CRISTALLINE DE CRISTAUX LIQUIDES THERMOTROPES POLYCATENAIRES A CELLE DE LEUR MESOPHASE, NOUS AVONS DETERMINE, PAR DIFFRACTION DES RAYONS X SUR MONOCRISTAL, LES STRUCTURES CRISTALLINES DE CINQ COMPOSES APPARTENANT A TROIS FAMILLES VOISINES, DONNANT, SOIT DES PHASES COLONNAIRES DE SYMETRIE HEXAGONALE, SOIT DES PHASES LAMELLAIRES ET NEMATIQUES. DANS TOUS LES CAS, L'ARRANGEMENT, A L'ETAT CRISTALLIN, EST DE TYPE SMECTIQUE C; LA PERIODE LAMELLAIRE ET INTERCOLONNAIRE CORRESPOND AU GRAND PARAMETRE CRISTALLOGRAPHIQUE. L'ETUDE DES PROFILS DES RAIES A PARTIR DU MONOCRISTAL, MONTRE QUE L'UN DES VECTEURS D'ONDE FONDAMENTAUX DE LA MESOPHASE HEXAGONALE A LA DIRECTION DE L'AXE 100 DU CRISTAL. L'AXE DES COLONNES RESTE PARALLELE AUX PLANS DES LAMELLES. L'ETUDE DILATOMETRIQUE NOUS A PERMIS D'ANALYSER LES COEFFICIENTS DE DILATATION THERMIQUE DES DIFFERENTES PHASES MESOMORPHES. LA COMBINAISON DE CES RESULTATS AVEC CEUX OBTENUS PAR DIFFRACTION DES RAYONS X NOUS A PERMIS DE DETERMINER LE NOMBRE DE MOLECULES PAR MOTIF ET PAR UNITE DE LONGUEUR LE LONG DE L'AXE DES COLONNES. ENFIN, L'ETUDE DE L'INFLUENCE DE LA PRESSION SUR LE COMPORTEMENT THERMODYNAMIQUE ET STRUCTURAL D'UN DE CES COMPOSES A CONDUIT AU CALCUL DES COEFFICIENTS DE COMPRESSIBILITE ISOTHERME ET DE CEUX DE DILATATION THERMIQUE ISOBARE. UNE ANALYSE, PAR DIFFRACTION DES RAYONS X SOUS PRESSION REALISEE DANS DES CONDITIONS SIMILAIRES, A COMPLETE L'ETUDE DE L'EVOLUTION STRUCTURALE DE CE COMPOSE
Author: Park S. Nobel
Publisher: Academic Press
ISBN: 0125200269
Category : Science
Languages : en
Pages : 589
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Book Description
"Physiology," which is the study of the function of cells, organs, and organisms, derives from the Latin physiologia, which in turn comes from the Greek physi- or physio-, a prefix meaning natural, and logos, meaning reason or thought. Thus physiology suggests natural science and is now a branch of biology dealing with processes and activities that are characteristic of living things. "Physicochemical" relates to physical and chemical properties, and "Environmental" refers to topics such as solar irradiation and wind. "Plant" indicates the main focus of this book, but the approach, equations developed, and appendices apply equalIy welI to animaIs and other organisms. We wilI specificalIy consider water relations, solute transport, photosynthesis, transpiration, respiration, and environmental interactions. A physiologist endeavors to understand such topics in physical and chemical terms; accurate models can then be constructed and responses to the internal and the external environment can be predicted. Elementary chemistry, physics, and mathematics are used to develop concepts that are key to under-standing biology -the intent is to provide a rigorous development, not a compendium of facts. References provide further details, although in some cases the enunciated principIes carry the reader to the forefront of current research. Calculations are used to indicate the physiological consequences of the various equations, and problems at the end of chapters provide further such exercises. Solutions to alI of the problems are provided, and the appendixes have a large tist of values for constants and conversion factors at various temperatures.
Author: Camille Flammarion
Publisher:
ISBN: 9781072589648
Category :
Languages : en
Pages : 188
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Book Description
Nicolas Camille Flammarion FRAS was a French astronomer and author. He was a prolific author of more than fifty titles, including popular science works about astronomy, several notable early science fiction novels, and works on psychical research and related topics.
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.
Author: International Institute of Refrigeration
Publisher:
ISBN:
Category : Refrigeration and refrigerating machinery
Languages : en
Pages : 688
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Book Description
Vols. 6- include supplementary material of Publications, Reports, Work, etc. of the Institute and some of its commissions.
Author: Rachilde
Publisher: Modern Language Association
ISBN: 1603292551
Category : Fiction
Languages : en
Pages : 272
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Book Description
When the rich and well-connected Raoule de Vénérande becomes enamored of Jacques Silvert, a poor young man who makes artificial flowers for a living, she turns him into her mistress and eventually into her wife. Raoule's suitor, a cigar-smoking former hussar officer, becomes an accomplice in the complications that ensue.
Author: Ahmed Belasri
Publisher: Springer Nature
ISBN: 9811554447
Category : Technology & Engineering
Languages : en
Pages : 659
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Book Description
This book highlights peer reviewed articles from the 1st International Conference on Renewable Energy and Energy Conversion, ICREEC 2019, held at Oran in Algeria. It presents recent advances, brings together researchers and professionals in the area and presents a platform to exchange ideas and establish opportunities for a sustainable future. Topics covered in this proceedings, but not limited to, are photovoltaic systems, bioenergy, laser and plasma technology, fluid and flow for energy, software for energy and impact of energy on the environment.
Author:
Publisher:
ISBN:
Category : Chemical reactions
Languages : en
Pages : 442
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Book Description
Author: Canada. Patent Office
Publisher:
ISBN:
Category : Copyright
Languages : un
Pages : 1036
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Book Description
Includes annual cumulative index of inventors and patentees.
