Tesis sobre el tema "Transition biophysique"
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Laarraj, Mohcine. "Nanocalorimètre dynamique pseudo-différentiel à haute sensibilité pour l'étude thermodynamique et cinétique de la transition vitreuse". Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAY029/document.
Texto completoThis thesis reports the working principle and the building up of a dynamic differential nanocalorimeter to the study of the glass transition. The micro-fabricated sensor, the low noise and highly stable measurement chain, as well as the thermal environment of the sensor are described in details. The measurement method is a spectroscopic method in which the amplitude and phase of the oscillating temperature are measured with a high resolution at different frequencies. The resolution of the nanocalorimeter on the measurement of the complex heat capacity module is ∆|C_p^* |/|C_p^* | ± 0,001 %, and on the phase of the temperature oscillation is ∆φ/φ ± 0, 0005 %. This resolution is about one thousand times higher than that of the commercial temperature modulated calorimeters. The potentialities of the nanocalorimeter for the study of fine thermodynamic and kinetic effects are demonstrated on a model of glassy polymer, the poly(vinyl acetate). New effects which are too fine to be detected by conventional calorimeters have been measured. The modulus of the complex heat capacity and the phase of the temperature oscillation exhibit small relaxational effects of low amplitude either in the super-cooled liquid state or in the glassy state. In addition, according to the thermal history followed by the material, the structural recovery of this polymer can take place in two steps during the heating. These two steps are visible only on the temperature derivative of the modulus of the complex heat capacity. In conclusion, resolution, stability and repeatability of the nanocalorimeter are particularly suitable for fine thermodynamic and kinetic study on out of equilibrium complex systems such as glasses
DIYIZOU, YVONNE. "Synthese d'une sonde phtosensible, transmembranaire et phospholipidique : etudes physicochimiques et photochimiques dans les vesicules". Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13105.
Texto completoRomby, Pascale. "Contribution a l'etude structurale et fonctionnelle de l'acide ribonucleique de transfert". Université Louis Pasteur (Strasbourg) (1971-2008), 1986. http://www.theses.fr/1986STR13100.
Texto completoAdam, Safia. "Etude des conformations secondaires d'ADN synthétiques pas spectrométrie optique". Paris 13, 1985. http://www.theses.fr/1985PA132001.
Texto completoDesnos, Hugo. "Amélioration des procédures de cryoconservation de type congélation-lente par simulation et caractérisation des effets de composés chitooligosaccharides". Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1048/document.
Texto completoWe wished to move aside classical cryopreservation procedure improvements that are based on empiricism and to focus on existing biophysical models in order to describe procedures. We based our study on two methods. The first method consisted in developing the methods for the simulations of procedures, by characterizing the use of Snomax in a DSC device. This study highlighted that the nucleation temperature (Tn) control is possible under precise experimental conditions (sample volume and Snomax concentration) that influence the presence probability of 3 INA subpopulations of the P. syringae protein aggregates. The possibility to simulate the cryopreservation procedures has been achieved for some supercooling ranges within complex cryopreservation solutions. Consequently, it has been possible to characterize the physical effects influenced by Tn and involved within procedures. These results will participate in supplying cryopreservation biophysical models. The second method aimed to modify the composition of cryopreservative solutions in order to reduce the DMSO use (because of its cytotoxicity), using extracellular CPA components: the chitooligosaccharides COS. Subsequent to the biocompatibility verification of the COS with embryonic cells, the thermodynamic influence of the COS has been characterized. Therefore, it has been demonstrated that COS are cryostabilizers that link themselves to a small number of water molecules and does not influence its physicochemical properties. Consequently, COS can be added within the extracellular space without any risk to accelerate the cell dehydration. It has been demonstrated that COS favor the gelation of the extracellular space and that this gelation relies on the mass proportion of water in the residual solution. This gelation immobilizes a part of the system and therefore favor its stabilization when the temperature reaches the risky recrystallization range
Cocco, Simona. "Uno studio teorico delle vibrazioni della struttura elicoidale del DNA B e della transizione di denaturazione". Lyon, École normale supérieure (sciences), 2000. http://www.theses.fr/2000ENSL0151.
Texto completoLazrak, Tarik. "Renforcateurs membranaires : etude structurale et evolution biochimique". Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13167.
Texto completoSalehi, Seyed-Taghi. "Etude de la dynamique de proteines par spectrometrie ultrasonore". Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13227.
Texto completoAndré, Alexander. "Force-induced structural transitions in cross-linked deoxyribonucleic acid films". Université Louis Pasteur (Strasbourg) (1971-2008), 2007. https://publication-theses.unistra.fr/restreint/theses_doctorat/2007/ANDRE_Alexander_2007.pdf.
Texto completoAndré, Alexander Kékicheff Patrick Maret Georg. "Force-induced structural transitions in cross-linked deoxyribonucleic acid films". Strasbourg : Université Louis Pasteur, 2008. http://eprints-scd-ulp.u-strasbg.fr:8080/00000868.
Texto completoThèse soutenue en co-tutelle. Titre provenant de l'écran-titre. Bibliogr. p. 135-148.
Hantz-Brachet, Edith. "Etude d'émulsions et de vésicules unilamellaires d'intérêt biologique ou pharmaceutique par diffusion quasiélastique de la lumière et spectroscopie vibrationnelle". Paris 13, 1989. http://www.theses.fr/1989PA132009.
Texto completoGallat, Francois-Xavier. "Dynamique des protéines et de la couche d'hydratation étudiée par diffusion de neutrons et méthodes biophysiques complémentaires". Thesis, Grenoble, 2011. http://www.theses.fr/2011GRENY061/document.
Texto completoThis thesis work focused on the dynamics of proteins, surrounded by their hydration layer, a water shell around the protein vital for its biological function. Each of these components is accompanied by a specific dynamics which union reforms the complex energy landscape of the system. The joint implementation of selective deuteration, incoherent neutron scattering and terahertz spectroscopy allowed to explore the dynamics of proteins and that of the hydration shell. The influence of the folding state of protein on its dynamics has been studied by elastic neutron scattering. Globular proteins were less dynamic than its intrinsically disordered analogues. Themselves appear to be stiffer than non physiological unfolded proteins. The oligomerization state and the consequences on the dynamics were investigated. Aggregates of a globular protein proved to be more flexible than the soluble form. In contrast, aggregates of a disordered protein showed lower average dynamics compared to the soluble form. These observations demonstrate the wide range of dynamics among the proteome. Incoherent neutron scattering experiences on the hydration layer of globular and disordered proteins have yielded information on the nature of water motion around these proteins. The measurements revealed the presence of translational motions concomitant with the onset of the transition dynamics of hydration layers, at 220 K. Measurements have also shown a stronger coupling between a disordered protein and its hydration water, compared to a globular protein and its hydration shell. The nature of the hydration layer and its influence on its dynamics has been explored with the use of polymers that mimic the water behavior and that act as a source of flexibility for the protein. Eventually, the dynamics of methyl groups involved in the dynamical changes observed at 150 and 220 K, was investigated
MUTET, HAYOTTE CHRISTINE. "Etude d'interactions proteines-membranes : cas particulier de l'aspartate aminotransferase mitochondriale". Université Louis Pasteur (Strasbourg) (1971-2008), 1986. http://www.theses.fr/1986STR13101.
Texto completoGutierrez, Cori Omar. "Relationship and feedback between LULC changes and hydroclimatic variability in Amazonia". Electronic Thesis or Diss., Sorbonne université, 2024. http://www.theses.fr/2024SORUS123.
Texto completoThe Amazon rainforest plays a vital role by functioning as a regulator of the climate system and as the main terrestrial carbon sink. It drives hydroclimatic processes and mitigates the effects of droughts through vegetation-atmosphere coupling. Indeed, Amazon forests have the potential to impact rainfall patterns through biophysical processes like water recycling. However, these capacities have been reduced during the last decades due to disturbances in the climate-vegetation system together with the intensification of droughts. All this has accentuated a process of biophysical transition from a predominantly forested ecosystem to a Savanna. Therefore, given these complexities, understanding the direction of changes is of vital importance.Using multiple datasets and the coupled ORCHIDEE and LMDZ models, this thesis delves into the study of the interactions between Amazon hydroclimatology and vegetation. In addition, it seeks to expand our understanding of modifications in the vegetation-atmosphere system and its links with climate and LULC changes. Likewise, taking into account the increasing rates of deforestation, it investigates the effects and feedback resulting from a large-scale forest loss scenario on hydrological processes.The results show that, over the southwestern Amazon, forests undergo a transition from being influenced by energy availability to depending on water availability throughout the year. During the rainy season, vegetation growth is primarily influenced by energy availability rather than water availability. Nevertheless, outside of this period, forests respond positively to precipitation and terrestrial water storage, suggesting that vegetation is primarily dependent on water supply. However, a spatial analysis reveals that recent deforestation modifies these transitions and destabilizes the natural balance in the climate-vegetation system.The nature of these imbalances in the Amazon is not entirely clarified. Through an approach based on the relationships of water/energy fluxes and vegetation conditions over the last four decades, it is explored whether these changes are intrinsic to climate variability or are driven by anthropogenic processes. 67% of the southwestern Amazon has experienced a transition towards a predominantly dry state due to climatic factors (external forcing), while 21% has transitioned towards a state dominated by deforestation (internal forcing). However, external and internal forcings are not independent processes, as both mechanisms drive changes simultaneously. By weighing the magnitudes of these forcings, we show that the synergies have led 74% of the southwestern Amazon toward a state of greater water stress. Nevertheless, during recent years, although combined external-internal processes continue to exert significant control over changes, 30% of these are strictly dominated by internal forcing. This suggests that internal processes are playing an increasingly relevant role in the transition towards a state characterized by high forest water stress, especially in areas where deforestation and anthropogenic pressure are increasing.Using the coupled ORCHIDEE and LMDZ models, the effects of projected Amazon deforestation by 2050 on the hydrological cycle and dryness are examined. Deforestation decreases precipitation, reduces evapotranspiration and increases runoff. Furthermore, deforestation accentuates water stress especially in the southwestern Amazon (positive feedback). Water demands in the atmosphere, on the land surface and even in the soil root zone intensify during the dry season. During the wet season, the deficit of specific atmospheric humidity becomes even more acute towards the tropical Andes over the Altiplano region. These findings provide a more thorough understanding of the possible effects of massive forest removal on the water availability and resilience of the Amazon in a context where changes are occurring at an accelerated rate
Gallat, Francois-xavier. "Dynamique des protéines et de la couche d'hydratation étudiée par diffusion de neutrons et méthodes biophysiques complémentaires". Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00758647.
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