376 research outputs found
Bioadhesive giant vesicles for monitoring hydroperoxidation in lipid membranes
No full textOsmotic stresses, protein insertion or lipid oxidation lead to area increase of self-assembled lipid membranes. However, methods to measure membrane expansion are scarce. Challenged by recent progress on the control of phospholipid hydroperoxidation, we introduce a method to quantitatively evaluate membrane area increase based on the bio-adhesion of Giant Unilamellar Vesicles.Institut Charles Sadron, Université de Strasbourg, CNRS UP 22Faculdade de Ciências e Tecnologia, UNESP Universidade Estadual Paulista, Presidente PrudenteSão Carlos Institute of Physics, University of São Paulo, CP 369Faculdade de Ciências e Tecnologia, UNESP Universidade Estadual Paulista, Presidente Prudent
Contribution à l'étude de la formation et de la propagation des anneaux de tourbillon dans l'air
No full textAyant repris les expériences relatives à la formation et à la propagation des anneaux de tourbillon, nous nous proposons, dans ce travail, d'exposer les résultats obtenus comparativement à ceux des travaux antérieurs
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Who was Who in Polymer Science: S
No full textSadron, Charles Saegusa, Takeo Sakurada, Ichiro Salamone, Joseph C. Schloegl, Karl deSchruyver, Frans Schulz, Rolf Schurz, Josef Sebenda, Jan Semenov, Nikolai Nikolaevich Seymour, Raymond Shida, Ken-ichi Shima, Mikiko Shopov, Ivan Sigwalt, Pierre Simionescu, Cristofer I. Smets, George Sobue, Hiroshi Solomon, David M. Stannett, Vivian Staudinger, Hermann Staverman, Albert Jan Stein, Richard S. Stille, John D. Stockmayer, Walter H. Sumitomo, Hiroshi Sundholm, Franciska Szwarc, Michae
Comparaison des propriétés physicochimiques du DNA natif et du DNA ultrasoné
No full textOn a étudié par diffusion de la lumière, ultracentrifugation et dénaturation thermique l’influence de la force ionique (solutions de NaCl 0,0015 M à 1 M) sur la configuration du DNA natif (Mm ~ 6.106) et du DNA fragmenté par sonication en batonnets (Mw ~ 0,6.106). Dans le cas du DNA natif, quand la force ionique du milieu décroît, il y a une augmentation des interactions intermoléculaires (second coefficient du viriel, extrapolation à concentration nulle pour déterminer les constantes de sédimentation). Dans les limites de force ionique étudiées, on n’a pu mettre en évidence aucune perturbation dans le comportement du DNA soniqué
Comparison between nucleation of pentacene monolayer islands on polymeric and inorganic substrates
No full textWe present a comparative study of the nucleation and growth of pentacene monolayer islands in the submonolayer regime onto inorganic substrates of SiO2 and sapphire (Al2O3) and organic substrates of poly(methyl-metacrylate) (PMMA). We have determined the scaling laws that govern the saturated nucleation density per unit area N as a function of two essential deposition parameters: the deposition rate κ and the substrate temperature Ts. For all substrates, we found N∝κδ, with 0.8⩽δ⩽1.2, and the Ts dependence of the nucleation density follows a typical activated Arrhenius law. Whereas a critical nucleus size of i=2 is obtained for all investigated substrates, the activation energy for nucleation depends significantly on the dielectric. The difference in activation energy of nucleation on PMMA and SiO2 is due to different molecule-substrate interactionsLOMMInst. Charles Sadron, Strasbourg, France860290
Blue Light-Emission from a Nanostructured Organic Polymer Semiconductor
No full textWe report on the enhancement of the photoluminescence (PL) intensity from a nanostructured organic material composed of nanosized aggregates of poly(para-phenylene) (PPP) in a polystyrene insulating matrix. In addition, the peak of the PL emission spectrum from these nanostructured organic semiconductors is blue-shifted from that of unstructured PPP. Furthermore, these PL characteristics correlate with the presence of an unusual sub-gap absorption feature that is present only in the nanostructured PPP. These results suggest the departure of the optical properties of random nanostructured organic polymers from their unstructured counterparts.LOEQInst charles sadron,f-67083 strasbourg,france. Romero, db, swiss fed inst technol,dept phys,ch-1015 lausanne,switzerland.ISI Document Delivery No.: RC173Cited Reference Count: 13Cited References:AUVRAY L, 1991, NEUTRON XRAY LIGHT SBURN PL, 1992, NATURE, V356, P47FRANCOIS B, 1991, SYNTHETIC MET, V41, P955FRIEND RH, 1987, J PHYS D APPL PHYS, V20, P1367GREM G, 1992, ADV MATER, V4, P36GUSTAFSSON G, 1992, NATURE, V357, P477HEEGER AJ, 1988, REV MOD PHYS, V60, P781LEISING G, 1989, SPRINGER SERIES SOLI, V91, P100MCCONNELL GA, 1993, PHYS REV LETT, V71, P2102NEUMARK GF, 1994, PHYS TODAY, V47, P26ROMERO DB, 1992, SOLID STATE COMMUN, V82, P183YOFFE AD, 1993, ADV PHYS, V42, P173ZHONG XF, 1991, MAKROMOL CHEM, V192, P227
APPLICATIONS OF PATH INTEGRAL LANGEVIN DYNAMICS TO WEAKLY BOUND CLUSTERS AND BIOLOGICAL MOLECULES
No full textAuthor Institution: Department of Chemistry, University of Waterloo, Waterloo, Ontario; N2L 3G1, Canada; Centre de Biophysique Moleculaire, CNRS, Rue Charles Sadron, 45071 Orleans, France; Department of Chemistry, University of Waterloo, Waterloo, Ontario; N2L 3G1, CanadaWe present the use of path integral molecular dynamics (PIMD) in conjunction with the path integral Langevin equation thermostat for sampling systems that exhibit nuclear quantum effects, notably those at low temperatures or those consisting mainly of hydrogen or helium. To test this approach, the internal energy of doped helium clusters are compared with white-noise Langevin thermostatting and high precision path integral monte carlo (PIMC) simulations. We comment on the structural evolution of these clusters in the absence of rotation and exchange as a function of cluster size. To quantify the importance of both rotation and exchange in our PIMD simulation, we compute band origin shifts for (He)-CO as a function of cluster size and compare to previously published experimental and theoretical shifts. A convergence study is presented to confirm the systematic error reduction introduced by increasing path integral beads for our implementation in the Molecular Modelling Toolkit (MMTK) software package. Applications to carbohydrates are explored at biological temperatures by calculating both equilibrium and dynamical properties using the methods presented
Urea-Comprising Single Core Diketopyrrolopyrrole Derivatives: Exploring the Synthesis, Self-Assembly and Charge Transport Properties
No full textSupramolecular electronics exploits the distinctive features stemming from noncovalent interactions, guiding the self-assembly of molecules to craft materials endowed with customized electronic functionalities. Hydrogen-bonded materials, characterized by their capacity to establish dynamic and stable networks, introduce an extra dimension to the development of supramolecular electronic systems. This study presents a comparative analysis of two remarkably small semiconductors utilizing diketopyrrolopyrrole functionalized with urea units as hydrogen-bonding motifs, strategically positioned at opposing ends of the conjugated core. We show how the subtle distinction in functionalization not only influences morphology and self-assembly dynamics via hydrogen-bonding and π-π stacking formation, but also holds significant consequences for ultimate charge transport properties. Our observations into the interplay of noncovalent interactions provide valuable insights and strategic pathways for the design of novel materials with enhanced electronic characteristics. © 2024 Wiley-VCH GmbH.The authors acknowledge the characterization facility of Institute Charles Sadron for UV-Vis measurements. A. R. C. and G. M. thank the Graduate School of Complex Systems Chemistry of Strasbourg for his doctoral fellowship funded by the French National Research Agency (CSC-IGS ANR-17-EURE-0016). A. R. C. and I. I. B. thank the Region Grand Est for the TOTALBOND PhD project. The authors thank the Agence Nationale de la Recherche (ANR JCJC TOTALBOND 2020) and the International Emerging Actions CNRS 2020 (SUPRAWAVE).Supporting InformationPeer reviewe
Electronic and structural evidences for charge transfer and localization in iodine-doped pentacene
No full textWe have investigated the doping mechanism of pentacene with iodine and its impact on the structure and on the electronic properties of single crystals, powders, and thin films in a large range of iodine concentration up to six iodine per pentacene (PEN) molecule (I/PEN = 6). Three regimes of doping have been identified. In the low doping regime I/PEN + cations and related species, for example, cation dimers (PEN+)2 and typical Raman signatures of the I3- and I5- species. Spin pairing of pentacene cation radicals is further supported by the observation of a thermally activated behavior of the ESR spin susceptibility. In the heavy doping regime (2 < I/PEN <= 6), all traces of structural order vanish, indicating that iodine penetrates within the (a,b) planes of the intercalate in a disordered manner, forming an amorphous-like material. This high degree of disorder results in increased charge localization. Most spin/charge species are ESR-silent and only a limited fraction (a few percents) exhibits a Curie-like susceptibility. Because of disorder, the macroscopic conductivity of doped pentacene single crystals does not exceed a few S/cm at 300 KLOMMLPIInst. Charles Sadron, Strasbourg, France Copyright 2005, IEE 8248970 1089-5639 charge transfer charge localization iodine-doped pentacene doping mechanism electronic property single crystals powders thin films iodine concentration pentacene structure electron spin resonance Pauli susceptibility delocalized holes valence band intermediate doping regime intercalation UV-vis spectra IR spectra cations cation dimers Raman spectra spin pairing ESR spin susceptibility structural order Curie-like susceptibility conductivity 300
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