Littérature scientifique sur le sujet « Cristallographie – Effets des hautes pressions »
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Articles de revues sur le sujet "Cristallographie – Effets des hautes pressions"
Lonvaud-Funel, Aline, Géraldine Dupont, Gérard Demazeau et J. Bignon. « Essais de mutage de vins blancs liquoreux par traitement aux hautes pressions ». OENO One 28, no 1 (31 mars 1994) : 57. http://dx.doi.org/10.20870/oeno-one.1994.28.1.1155.
Texte intégralLE NEINDRE, Bernard. « Effets des hautes et très hautes pressions ». Caractérisation et propriétés de la matière, décembre 1990. http://dx.doi.org/10.51257/a-v1-k484.
Texte intégralThèses sur le sujet "Cristallographie – Effets des hautes pressions"
Kadri, Adel. « Aspects physico-chimiques des effets de la pression sur la cristallogenèse des protéines ». Université Louis Pasteur (Strasbourg) (1971-2008), 2004. http://www.theses.fr/2004STR13024.
Texte intégralSyamala, Vishnu Vijayakumar. « Molecular organization in solid-state using sigma-hole interactions : Exploring the effect of crystalline environment ». Electronic Thesis or Diss., Université de Lorraine, 2022. https://docnum.univ-lorraine.fr/ulprive/DDOC_T_2022_0214_VIJAYAKUMAR_SYAMALA.pdf.
Texte intégralUnderstanding the fundamentals of the formation and stabilization of non-covalent interactions is of paramount importance in the field of crystal engineering. In this direction, this thesis reports the crystallographic investigation of a sub-class of non-covalent interactions known as sigma-hole interactions. sigma-hole interactions are defined as those involving electrophilic sites (also called sigma-holes) associated to a covalently bonded atom belonging to either p-block (groups 13-18) or d-block (groups 8,11 and 12) of the periodic table, and nucleophilic sites coming from either the same or a different molecule. Depending upon the group of the atom on which the sigma-hole is present, the interaction can be further classified into various sub-classes. Out of these, we have focused on the cases of halogen bond (HaB) and chalcogen bond (ChB) interactions. As compared to the well-established case of hydrogen bonds (HB), the rationale behind the formation and stabilization of HaB and ChB are still less explored. This thesis is aimed exactly in such a direction, to provide a deeper insight into the characteristics of HaB and ChB interactions, mainly by understanding how the electron density is distributed among the interacting pair of atoms and how it eventually influences the molecular organization in solid-state. Two main stream topics of crystallography are covered during the course of this thesis: (i) high-pressure X-ray diffraction studies and (ii) charge density analysis. Structural and electronic investigations are carried out based on the data derived from single-crystal X-ray diffraction (SCXRD) experiments performed either at ambient or extreme conditions. The so-obtained crystal structures were used to derive the electron density distribution in the periodic phases. The electron distributions of the molecular systems extracted from their crystalline environments were used to calculate the electrostatic potential in molecular surfaces and to carry out the topological analyses of the electron density and its laplacian function within the framework of the Quantum Theory of Atoms in Molecules (QTAIM) methodology. The effect of crystalline environments in tuning the properties of sigma-hole interactions is also explored in detail. The information gathered from such analyses is not only helpful to better understand the molecules in hands, but also to design new molecular patterns with the aim to control the structure-properties relationship in molecular crystals
Djomani-Siawa, Doriane. « Hétérostructures allotropiques de semiconducteurs IV dans des nanofils : nouvelles opportunités more-than-Moore ». Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS074/document.
Texte intégralWe have demonstrated an original way to induce a phase transformation in Si and Ge nanowires under external shear-stress. The transformation results in an unprecedented heterostructure with quasiperiodic embedded Ge-2H nanodomains distributed all along the nanowire. My thesisproject aims at understanding the mechanisms of this phase transformation and at characterizing the physical properties of the heterostructures 2H/3C in Si and Ge nanowires.We have carried out systematic structural analysis in Si- and Ge-2H/3C nanowires to evidence the key parameters of this phase transformation.The phase transformation occurs in shear bands localized along the (2-5-5) direction.The heterostructured nanowires are defined by a specific orientation relationship between the 3C and the 2H bands (both in Si and Ge nanowires)given by(1-10)3C//(-2110)2H and (110)3C//(0001)2H with the 2H bands lying mainly on (115)3C planes.The preliminary studies showed that shear-stress and the thermal budget above a threshold temperature of 350°C in Ge and 500°C in Si are mandatory for this transformation. These conditions meet the common criteria of a martensitic phase transformation. We have identified two key intrinsic parameters:the temperature and the nanowires crystallographic axis.In Si nanowires, we found that the formation of the shear bands i.e. the 2H nanodomains is related to the component of the shear-stress along the glide direction of the 3C/2H interface plane.Based on these results,the transformation could be consistent with a stress relief mechanism through the formation of (5-5-2)(1-15)3C shear bands.We have performed spatially resolved Raman measurements on single Si and Ge heterostructured nanowires to characterize their optical phonon modes.In Ge,we have detected 2 Raman bands at 288 cm⁻ ᴵ and 301 cm⁻ ᴵ attributed to the E2g and E1g + A1g + F2g modes.In Si, we have observed 3 Raman bands at 498, 515 and 520 cm⁻ ᴵ that are associated respectively to the E2g, A1g and F2g modes.Those values agree well with the literature.Moreover, we have performed Fourier Transform Infrared spectroscopy on transformed Ge nanowires to measure the optical band gap of the 2H phase.We have obtained a direct band gap of 0,58 eV attributed to the 2H phase and an indirect bandgap of 0,72 eV that might stem from the 3C phase. Those results are the first experimental data of the Ge-2H band gap.The values align well with the simulations that predict a narrow direct band gap for this structure.The 2H structure can also be achieved in bulk Si and Ge after unloading of the BC8 phase in a diamond anvil cell.The BC8 phase is unstable and convertsinto the 2H phase at room temperature in Ge or by thermal annealing in Si.In order to compare the bulk properties of the 2H phase, we have performedin-situ Raman and X-ray diffraction experiments in bulk samples by studyingvarious unloading pathways. In particular, unloading at room temperature ledto the formation of the ST12 phase or a mixture of the BC8 and ST12 phasesdepending on the unloading rate.The formation of the 2H phase is thuscomplex given its dependency on the unloading conditions and the hydrostaticconditions within the cell that are difficult to garanty. Our studies also reveala size effect. After unloading of Ge-3C nanowires, the nanostructures revertback to the 3C phase with an amorphous component detected.In addition, we have carried out in-situ band gap measurements in bulk Ge and Ge nanowires as a function of pressure.After unloading, we havemeasured optical gap values that are related to the band structure of theGe-ST12 allotrope with a direct bandgap of 0,53 eV and an indirect bandgapof 0,73 eV.Those results are consistent with the experimental values reported.The experiments on Ge nanowires showed an hysteresis behavior with theinitial value of the band gap measured after unloading.Those results clearly evidenced novel relaxation mechanisms at the nanoscale that need to be investigated
Guerrero, François. « Etude des effets des hautes pressions sur le debit carotidien ». Aix-Marseille 2, 1993. http://www.theses.fr/1993AIX20660.
Texte intégralMarie, Philippe. « Conception et développement d'un nouveau procédé d'émulsification par haute pression ». Dijon, 2003. http://www.theses.fr/2003DIJOS054.
Texte intégralNabhan, Mohamad Ammar. « Protéolyse et redistribution des protéines entre différentes fractions azotées après traitement du lait par hautes pressions ». Vandoeuvre-les-Nancy, INPL, 2004. http://www.theses.fr/2004INPL054N.
Texte intégralThe thermal treatments induce frequently undesirable modifications in foods that could be avoided by the use of minimum treatment strategies. Among these treatments, high pressures are already commercialized by the alimentary industry. Pressure/temperature combination induced denaturation of beta-lactogiobulin and the formation of aggregates composed principally of beta-lactogiobulin, kappa-casein and of aipha-lactaibumin and of alphas1-casein at a lesser extent. The treatment reduce plasmin activity and induce an irreversible unfolding of alpha-lactaibumin at pH 7. 0 and a significant quantity was recovered in proteose-peptones fraction. To ensure the stability of natural microflora of milk during 21 days, milk must be treated at least 400 MPa and at comparatively extreme temperature. To eliminate completely the studied pathogen bacteria and ensure no surviving during 21 days, a treatment of at least 500 MPa and 55°C for 5 min minimum is necessary. Our results show that pressurized milks present an odor, a taste, a color and a texture different of pasteurized milk. Although different, the jury do not mark preference to any milk tested
Douzals, Jean-Paul. « Effets des hautes pressions isostatiques sur les modifications physico-chimiques de l'amidon ». Dijon, 1999. http://www.theses.fr/1999DIJO5004.
Texte intégralCanelon, Carlos Eduardo. « Cinétique de floculation des asphaltènes dans les mélanges n-heptane-toluène et étude de leur stabilité dans le brut en présence de CO2 à haute pression et haute température ». Pau, 2006. http://www.theses.fr/2006PAUU3004.
Texte intégralThe first part of this thesis focuses on an experimental study of the kinetic of asphaltenes flocculation of theVenezuelan crude oils Furrial and Hamaca. The influence of the ratio resins-asphaltenes and n-heptane-toluene, on the flocculation constant rate analyzed. The experimental results are interpreted and modelled by an osmotic micro-model allowing to illustrate the stabilizing effect of the absorption of resins on asphaltene colloids. In the second part, an original device with high sensitivity and precision is presented. It allows measurements of structural modifications occurring in opaque paraffinic and of asphaltenic crudes at high pressure and temperature (0. 1 to 70 MPa and 273 - 473 K). Experimental results of the effects of CO2 injection into two Venezuelan crude oils (Furrial et Jusepin) are also reported
En la primera parte de esta memoria hemos abordado el estudio de la cinética de floculación de asfaltenos de crudos venezolanos Furrial y Hamaca. Analizamos la influencia de la relación entre la concentración de resinas-asfaltenos y la n-heptano-tolueno, sobre la constante de velocidad de floculación. Los resultados experimentales son interpretados y discutidos en términos de un micro-modelo osmótico que permite ilustrar el efecto estabilizador de la adsorción de resinas sobre la periferia coloidal de los asfaltenos. En la segunda parte, se presenta un dispositivo experimental original con una alta sensibilidad que permite mediciones de las modificaciones estructurales de medios opacos parafinicos y de asfaltenos, en condiciones de alta presión y temperatura (0,1 a 70 MPa y 273 a 473 K). Igualmente, se muestran los resultados experimentales obtenidos del efecto de inyección de CO2 para dos crudos venezolanos (Furrial y Jusepin)
Risso, Jean-Jacques. « Recherches concernant les effets neurochimiques des hautes pressions d'hélium chez le mammifère de laboratoire : contribution à l'étude des mécanismes du syndrôme nerveux des hautes pressions ». Lyon 1, 1987. http://www.theses.fr/1987LYO10014.
Texte intégralRisso, Jean-Jacques. « Recherches concernant les effets neurochimiques des hautes pressions d'hélium chez le mammifère de laboratoire contribution à l'étude des mécanismes du syndrome nerveux des hautes pressions / ». Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37609397k.
Texte intégralLivres sur le sujet "Cristallographie – Effets des hautes pressions"
Andrzej, Katrusiak, McMillan Paul Francis 1955- et North Atlantic Treaty Organization. Scientific Affairs Division., dir. High-pressure crystallography. Dordrecht : Kluwer Academic Publishers, 2004.
Trouver le texte intégral(Editor), Andrzej Katrusiak, et Paul McMillan (Editor), dir. High-Pressure Crystallography (NATO Science Series II : Mathematics, Physics and Chemistry). Springer, 2004.
Trouver le texte intégral(Editor), Andrzej Katrusiak, et Paul McMillan (Editor), dir. High-Pressure Crystallography (NATO Science Series II : Mathematics, Physics and Chemistry). Springer, 2004.
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