9 results on '"Instituto de Física da Universidade Federal da Bahia (UFBA)"'
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2. Universal Scaling of the Velocity Field in Crack Front Propagation
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Julien Chopin, Pierre Le Doussal, Laurent Ponson, Clément Le Priol, Alberto Rosso, Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Laboratoire de Physique Théorique de l'ENS (LPTENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut Jean Le Rond d'Alembert (DALEMBERT), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Instituto de Fisica, Universidade Federal da Bahia (IF-UFB), Universidade Federal da Bahia (UFBA)-Instituto de Fisica, Laboratoire de physique de l'ENS - ENS Paris (LPENS), Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Sorbonne Université (SU)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Champs Aléatoires et Systèmes hors d'Équilibre, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Sorbonne Université (SU)-École normale supérieure - Paris (ENS Paris), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Instituto de Física da Universidade Federal da Bahia (UFBA), Universidade Federal da Bahia (UFBA), Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Université de Paris (UP)-Centre National de la Recherche Scientifique (CNRS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Université de Paris (UP)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)
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Physics ,Imagination ,[PHYS]Physics [physics] ,Phase transition ,Statistical Mechanics (cond-mat.stat-mech) ,media_common.quotation_subject ,Front (oceanography) ,General Physics and Astronomy ,FOS: Physical sciences ,Fracture mechanics ,Renormalization group ,01 natural sciences ,0103 physical sciences ,Vector field ,Statistical physics ,010306 general physics ,Scaling ,Critical exponent ,Condensed Matter - Statistical Mechanics ,media_common - Abstract
The propagation of a crack front in disordered materials is jerky and characterized by bursts of activity, called avalanches. These phenomena are the manifestation of an out-of-equilibrium phase transition originated by the disorder. As a result avalanches display universal scalings which are however difficult to characterize in experiments at finite drive. Here we show that the correlation functions of the velocity field along the front allow to extract the critical exponents of the transition and to identify the universality class of the system. We employ these correlations to characterize the universal behavior of the transition in simulations and in an experiment of crack propagation. This analysis is robust, efficient and can be extended to all systems displaying avalanche dynamics., Comment: 5 pages + 6 pages SupMat, 5+4 figures
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- 2019
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3. Nonlinear Viscoelastic Modeling of Adhesive Failure for Polyacrylate Pressure-Sensitive Adhesives
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Chopin, Julien, Villey, Richard, Yarusso, David, Barthel, Etienne, Creton, Costantino, Ciccotti, Matteo, Sciences et Ingénierie de la Matière Molle (UMR 7615) (SIMM), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Instituto de Física da Universidade Federal da Bahia (UFBA), Universidade Federal da Bahia (UFBA), SAINT GOBAIN GLASS France CRDC, Saint Gobain, 3M Company, Université Paris sciences et lettres (PSL), HAL-UPMC, Gestionnaire, and Bresson, Bruno
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[PHYS]Physics [physics] ,[PHYS.COND]Physics [physics]/Condensed Matter [cond-mat] ,[PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft] ,[PHYS.COND] Physics [physics]/Condensed Matter [cond-mat] ,ComputingMilieux_MISCELLANEOUS ,[PHYS] Physics [physics] ,[PHYS.COND.CM-SCM] Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft] - Abstract
International audience; We investigate experimentally the adherence energy Γ of model polyacrylate Pressure Sensitive Adhesives (PSAs) with combined large strain rheological measurements in uniaxial extension and an instrumented peel test. We develop a nonlinear model for such peel test which captures the dependence of Γ(V) with peeling rate V revealing the key role played by the extensional rheology. Our model explains in particular why traditional linear viscoelastic approaches correctly predict the slope of Γ(V) curves for sufficiently elastic PSAs characterized by a simple rate-independent debonding criterion. However, for more viscoelastic adhesives, we identified a more complex rate-dependent debonding criterion yielding a significant modification of the Γ(V) curves, an effect that has been largely overlooked so far. This investigation opens the way towards the understanding of fibrils debonding, which is the main missing block to predict the adherence of PSAs.
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- 2018
4. Modulation of AMPA receptor surface diffusion restores hippocampal plasticity and memory in Huntington’s disease models
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Chun-Lei Zhang, Yoon H. Cho, Matthieu Sainlos, Sophie Daburon, Yann Humeau, Denis J. David, Hongyu Zhang, Jean Vincent, Frédéric Saudou, Diana Zala, Dolors Grillo-Bosch, Daniel Choquet, Caroline Benstaali, Françoise Coussen, Microsoft Research Asia, Chinese Academy of Agricultural Sciences (CAAS), Ecole normale mixte, Châlons sur Marne (ENM), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL), Interdisciplinary Institute for Neuroscience (IINS), Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB), Composantes innées de la réponse immunitaire et différenciation (CIRID), Université Bordeaux Segalen - Bordeaux 2-Centre National de la Recherche Scientifique (CNRS), Physiologie cellulaire de la synapse (PCS), Université Bordeaux Segalen - Bordeaux 2-Institut François Magendie-Centre National de la Recherche Scientifique (CNRS), Instituto de Física da Universidade Federal da Bahia (UFBA), Universidade Federal da Bahia (UFBA), Régulations cellulaires et oncogenèse (RCO), Institut Curie [Paris]-Centre National de la Recherche Scientifique (CNRS), Interdisciplinary Institute for Neuroscience, and Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS)
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0301 basic medicine ,Scaffold protein ,Thiazepines ,Science ,[SDV.NEU.NB]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,Neurogenesis ,Long-Term Potentiation ,General Physics and Astronomy ,Mice, Transgenic ,AMPA receptor ,Tropomyosin receptor kinase B ,Hippocampal formation ,Hippocampus ,General Biochemistry, Genetics and Molecular Biology ,Article ,Diffusion ,03 medical and health sciences ,0302 clinical medicine ,Neurotrophic factors ,Memory ,medicine ,Animals ,Receptor, trkB ,Tianeptine ,Receptors, AMPA ,lcsh:Science ,ComputingMilieux_MISCELLANEOUS ,Multidisciplinary ,Neuronal Plasticity ,Chemistry ,musculoskeletal, neural, and ocular physiology ,Brain-Derived Neurotrophic Factor ,Long-term potentiation ,General Chemistry ,Mice, Inbred C57BL ,Disease Models, Animal ,Protein Transport ,030104 developmental biology ,Huntington Disease ,nervous system ,Synaptic plasticity ,Synapses ,lcsh:Q ,Neuroscience ,030217 neurology & neurosurgery ,medicine.drug ,Signal Transduction - Abstract
Impaired hippocampal synaptic plasticity contributes to cognitive impairment in Huntington’s disease (HD). However, the molecular basis of such synaptic plasticity defects is not fully understood. Combining live-cell nanoparticle tracking and super-resolution imaging, we show that AMPAR surface diffusion, a key player in synaptic plasticity, is disturbed in various rodent models of HD. We demonstrate that defects in the brain-derived neurotrophic factor (BDNF)–tyrosine receptor kinase B (TrkB) signaling pathway contribute to the deregulated AMPAR trafficking by reducing the interaction between transmembrane AMPA receptor regulatory proteins (TARPs) and the PDZ-domain scaffold protein PSD95. The disturbed AMPAR surface diffusion is rescued by the antidepressant drug tianeptine via the BDNF signaling pathway. Tianeptine also restores the impaired LTP and hippocampus-dependent memory in different HD mouse models. These findings unravel a mechanism underlying hippocampal synaptic and memory dysfunction in HD, and highlight AMPAR surface diffusion as a promising therapeutic target., Cognitive decline in Huntington’s disease (HD) may be due to impaired hippocampal synaptic plasticity. In this study the authors show that AMPA receptor surface diffusion, a key player in synaptic plasticity, is deregulated in multiple HD mouse models as a result of impaired BDNF signalling that underlies the memory deficits, and can be pharmacologically rescued.
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- 2018
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5. Derivation of Hamaker Dispersion Energy of Amorphous Carbon Surfaces in Contact with Liquids Using Photoelectron Energy-Loss Spectra
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D. David, Christian Godet, Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Instituto de Física da Universidade Federal da Bahia (UFBA), Universidade Federal da Bahia (UFBA), PVE 400691/2012-4, CNPq, CAPES BEX 0281/15-8, CAPES, and Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS)
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Physics ,General Physics and Astronomy ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,7. Clean energy ,01 natural sciences ,0104 chemical sciences ,Contact angle ,Surface tension ,Carbon film ,Amorphous carbon ,X-ray photoelectron spectroscopy ,[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] ,Cutoff ,Wave vector ,Atomic physics ,0210 nano-technology ,Spectroscopy ,ComputingMilieux_MISCELLANEOUS - Abstract
Hamaker interaction energies and cutoff distances have been calculated for disordered carbon films, in contact with purely dispersive (diiodomethane) or polar (water) liquids, using their experimental dielectric functions e (q, ω) obtained over a broad energy range. In contrast with previous works, a q-averaged q is derived from photoelectron energy-loss spectroscopy (XPS-PEELS) where the energy loss function (ELF) q is a weighted average over allowed transferred wave vector values, q, given by the physics of bulk plasmon excitation. For microcrystalline diamond and amorphous carbon films with a wide range of (sp3/sp2 + sp3) hybridization, non-retarded Hamaker energies, A 132 (L
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- 2017
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6. Derivation of dielectric function and inelastic mean free path from photoelectron energy-loss spectra of amorphous carbon surfaces
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Christian Godet, D. David, Instituto de Física da Universidade Federal da Bahia (UFBA), Universidade Federal da Bahia (UFBA), Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), One of us (C.G.) is grateful to CNPq agency for a visiting researcher grant (PVE 400691/2012-4) in the Ciência Sem Fronteiras programme. One of us (D.D.) is grateful to CAPES agency (Brazil) for a senior researcher grant and University of Rennes 1 for an invited professor position., and Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS)
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Free electron model ,Plasmons ,Materials science ,Plasmon excitations ,X ray photoelectron spectroscopy ,General Physics and Astronomy ,Electrons ,02 engineering and technology ,Dielectric functions ,Plasma oscillation ,01 natural sciences ,7. Clean energy ,X-ray photoelectron spectroscopy ,X ray photoelectron spectra ,0103 physical sciences ,Near-surface materials ,Chemical analysis ,Surface plasmon excitation ,Plasmon ,010302 applied physics ,[PHYS]Physics [physics] ,Photons ,Surface excitation parameters ,Plasma oscillations ,Electron energy loss spectroscopy ,Energy dissipation ,Surface plasmon ,Amorphous carbon ,Surfaces and Interfaces ,General Chemistry ,Inelastic mean free path ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Surface plasmon polariton ,Surfaces, Coatings and Films ,Photoelectron spectroscopy ,Electronic properties ,Atomic physics ,0210 nano-technology ,Amorphous films ,Carbon films ,Photoelectrons ,Dielectric response theory ,Electric excitation - Abstract
International audience; Photoelectron Energy Loss Spectroscopy (PEELS) is a highly valuable non destructive tool in applied surface science because it gives access to both chemical composition and electronic properties of surfaces, including the near-surface dielectric function. An algorithm is proposed for real materials to make full use of experimental X-ray photoelectron spectra (XPS). To illustrate the capabilities and limitations of this algorithm, the near-surface dielectric function ε(ℏω) of a wide range of amorphous carbon (a-C) thin films is derived from energy losses measured in XPS, using a dielectric response theory which relates ε(ℏω) and the bulk plasmon (BP) loss distribution. Self-consistent separation of bulk vs surface plasmon excitations, deconvolution of multiple BP losses and evaluation of Bethe-Born sensitivity factors for bulk and surface loss distributions are crucial to obtain several material parameters: (1) energy loss function for BP excitation, (2) dielectric function of the near-surface material (3–5 nm depth sensitivity), (3) inelastic mean free path, λP (E0), for plasmon excitation, (4) surface excitation parameter, (5) effective number NEFF of valence electrons participating in the plasma oscillation. This photoelectron energy loss spectra analysis has been applied to a-C and a-C:H films grown by physical and chemical methods with a wide range of (sp3/sp2 + sp3) hybridization, optical gap and average plasmon energy values. Different methods are assessed to accurately remove the photoemission peak tail at low loss energy (0–10 eV) due to many-body interactions during the photo-ionization process. The σ + π plasmon excitation represents the main energy-loss channel in a-C; as the C atom density decreases, λP (970 eV) increases from 1.22 nm to 1.6 nm, assuming a cutoff plasmon wavenumber given by a free electron model. The π-π* and σ-σ* transitions observed in the retrieved dielectric function are discussed as a function of the average (sp3/sp2 + sp3) C hybridization and compared with literature results.
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- 2016
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7. Metal-insulator transition and superconductivity in boron-doped diamond
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Julien Pernot, Christophe Marcenat, Clas Persson, Jacques Marcus, Etienne Bustarret, J. Kačmarčik, C. Cytermann, Frederik Gustafsson, Thierry Klein, Franck Omnès, Bo E. Sernelius, Philipp Achatz, A. Ferreira Sa Silva, Magnétisme et Supraconductivité (MagSup), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), Semi-conducteurs à large bande interdite (SC2G), Slovakian Academy of sciences - Institut of Experimental Physics (SAS), Slovakian Academy of sciences, Département de Recherche Fondamentale sur la Matière Condensée (DRFMC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Automatisation et Caractérisation (AUTOCARAC), Department of Physics, Chemistry and Biology [Linköping] (IFM), Linköping University (LIU), Department of Materials Science and Engineering, KTH (KTH), Department of Materials Science and Engineering, KTH, Instituto de Física da Universidade Federal da Bahia (UFBA), Universidade Federal da Bahia (UFBA), Solid State Institute, Solid State Institute, Technion, Magnétisme et Supraconductivité (NEEL - MagSup), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS), Semi-conducteurs à large bande interdite (NEEL - SC2G), and Automatisation & caractérisation (NEEL - AUTOCARAC)
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superconducting transition temperature ,superconducting thin films ,02 engineering and technology ,01 natural sciences ,Variable-range hopping ,hopping conduction ,Pseudopotential ,diamond ,Condensed Matter::Superconductivity ,Naturvetenskap ,0103 physical sciences ,Coulomb ,metal-insulator transition ,Metal–insulator transition ,superconducting materials ,010306 general physics ,Boron doped diamond ,Superconductivity ,Physics ,Condensed matter physics ,superconductivity ,Hall effect ,Order (ring theory) ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,[PHYS.COND.CM-S]Physics [physics]/Condensed Matter [cond-mat]/Superconductivity [cond-mat.supr-con] ,Boron concentration ,electron-phonon interactions ,superconducting transitions ,71.30.+h, 71.20.Nr, 74.25.Fy ,boron ,Natural Sciences ,0210 nano-technology - Abstract
We report on a detailed analysis of the transport properties and superconducting critical temperatures of boron-doped diamond films grown along the {100} direction. The system presents a metal-insulator transition (MIT) for a boron concentration (nB) on the order of nc~4.5×1020 cm−3, in excellent agreement with numerical calculations. The temperature dependence of the conductivity and Hall effect can be well described by variable range hopping for nBnc) present a superconducting transition at low temperature. The zero-temperature conductivity 0 deduced from fits to the data above the critical temperature (Tc) using a classical quantum interference formula scales as 0(nB/nc−1) with ~1. Large Tc values (0.4 K) have been obtained for boron concentration down to nB/nc~1.1 and Tc surprisingly mimics a (nB/nc−1)1/2 law. Those high Tc values can be explained by a slow decrease of the electron-phonon coupling parameter and a corresponding drop of the Coulomb pseudopotential µ* as nBnc. Original Publication:T. Klein, P. Achatz, J. Kacmarcik, C. Marcenat, F. Gustafsson, J. Marcus, E. Bustarret, J. Pernot, F. Omnes, Bo Sernelius, C. Persson, A. Ferreira da Silva and C. Cytermann, Metal-insulator transition and superconductivity in boron-doped diamond, 2007, Physical Review B. Condensed Matter and Materials Physics, (75), 165313.http://dx.doi.org/10.1103/PhysRevB.75.165313Copyright: American Physical Societyhttp://www.aps.org/
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- 2007
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8. Distribution of uranium in soil profiles of Bahia State, Brazil
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Gaston Sieffermann, Lycia Maria Moreira-Nordemann, Instituto de Física da Universidade Federal da Bahia (UFBA), Universidade Federal da Bahia (UFBA), Centre des Faibles Radioactivités, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), ORSTOM - Bondy, ORSTOM, and Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
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inorganic chemicals ,[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere ,010504 meteorology & atmospheric sciences ,Soil test ,Isotopes of uranium ,Radiochemistry ,technology, industry, and agriculture ,Soil Science ,chemistry.chemical_element ,Sorption ,Uranium ,010502 geochemistry & geophysics ,complex mixtures ,01 natural sciences ,Uranium-238 ,chemistry ,Environmental chemistry ,Uranium-234 ,Soil water ,Parent rock ,[SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment ,ComputingMilieux_MISCELLANEOUS ,0105 earth and related environmental sciences - Abstract
In the present work we study five soil profiles and explain the measured uranium concentrations on the basis of an isovolumetric reasoning. The results show that, despite an important loss of uranium to the outgoing solutions when the parent rock is transformed into alterite and soil, the relative concentration in the residual soil increases. To improve our knowledge of the distribution of uranium in the components of the soil, we measured its concentrations in clays and heavy minerals, which are the main bearers of uranium. To explain the phenomena of adsorption and desorption of uranium in clays, we performed, in the laboratory, lixiviation experiments on soil samples washed by water enriched in organic and mineral matter.
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- 1979
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9. Etude expérimentale du rapport 234U/238U dans les eaux naturelles ayant traversé différents types de roches
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Moreira, Lycia, Lalou, Claude, Instituto de Física da Universidade Federal da Bahia (UFBA), Universidade Federal da Bahia (UFBA), Centre des Faibles Radioactivités, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Aptel, Florence, and Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
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[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere ,[SDU.OCEAN] Sciences of the Universe [physics]/Ocean, Atmosphere ,[SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment ,[SDU.ENVI] Sciences of the Universe [physics]/Continental interfaces, environment ,ComputingMilieux_MISCELLANEOUS - Abstract
International audience
- Published
- 1972
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