Chains in critical fluids and nanopores

The conformational behavior of a polymer in a critical binary solvent confined in a porous medium is studied. The size of the polymer in bulk, which is mainly governed by the correlation length of the solvent density fluctuations, depends on the proximity to the critical point of the binary mixture. We find that in contrast to the bulk behavior, the conformational properties of the polymer in a porous medium depends strongly on the pore size. The latter controls the correlation length of the solvent density fluctuations and thus determines the polymer size.Comment: 6 page

Mean-Field-Theory for Polymers in Mixed Solvents Thermodynamic and Structural Properties

Theoretical aspects of polymers in mixed solvents are considered using the Edwards Hamiltonian formalism. Thermodynamic and structural properties are investigated and some predictions are made when the mixed solvent approaches criticality. Both the single and the many chain problems are examined. When the pure mixed solvent is near criticality, addition of a small amount of polymers shifts the criticality towards either enhanced compatibility or induced phase separation depending upon the value of the parameter describing the interaction asymmetry of the solvents with respect to the polymer. The polymer-solvent effective interaction parameter increases strongly when the solvent mixture approaches criticality. Accordingly, the apparent excluded volume parameter decreases and may vanish or even become negative. Consequently, the polymer undergoes a phase transition from a swollen state to an unperturbed state or even take a collapsed configuration. The effective potential acting on a test chain in strong solutions is calculated and the concept of Edwards screening discussed. Structural properties of ternary mixtures of polymers in mixed solvents are investigated within the Edwards Hamiltonian model. It is shown that the effective potential on a test chain in strong solutions could be written as an infinite series expansion of terms describing interactions via one chain, two chains etc. This summation can be performed following a similar scheme as in the Ornstein-Zernike series expansion.Comment: accepted in Macromol. Theory Simu

A q-deformed Aufbau Prinzip

A building principle working for both atoms and monoatomic ions is proposed in this Letter. This principle relies on the q-deformed chain SO(4) > G where G = SO(3)_q

Hydrogen-oscillator connection: passage formulas between wave functions

Starting from Michel Foucault's conception of devices in terms of power, this article focuses on the subjective relationship that we experiment with devices, based on playing and illusion. The concept of device will be put in perspective of various conceptions: the tactical uses of technology developed by Michel de Certeau, Winnicott's transitional objects, and heterotopy also by Foucault. These conceptions will lead us to consider devices as texts, which means productivity. Thus, it will be possible to take into account the illusionary part of our relationship to world mediated by devices. Such a position is necessary to understand devices as a resource and not only as a technology of control. This change of perspective will lead us to examine the construction of the symbolic understanding of our word by using devices. These theoretical positions will then help us to investigate the mediations over the Internet as a possible way to articulate the subjective relationship to devices with the social construction of meaning

Bioremédiation fongique de 2 HAPs (phylogénie par AFLP de souches performantes d'Aspergillus de la section Nigri)

Notre étude porte sur des polluants particuliers, les HAPs (Hydrocarbures Aromatiques Polycycliques) produits spontanément lors de la combustion incomplète de nombreuses matières organiques. Doués de propriétés toxiques, cancérigènes et tératogènes avérées en expérimentation animale, ces composés hydrophobes, en s'adsorbant aux particules, persistent généralement dans les sols et les sédiments. Pour faire face à ces nuisances, des méthodes alternatives de dépollution telle que la bioremédiation (utilisation d'organismes vivants) sont actuellement mises en place. Elles découlent de travaux de recherche démontrant le rôle du compartiment microbien dans la dégradation des HAPs. Au cours de cette étude, 4 axes de recherches ont été développés : l'identification et la caractérisation des micromycètes présents dans un bassin contaminé par du FA, par comparaison avec un bassin témoin ; l'évaluation des capacités biorémédiatrices des souches isolées vis-à-vis de deux molécules modèles de HAPs (l'AC et le FA) en milieu solide et en milieu liquide ; la compréhension des phénomènes mis en jeu par l'étude en cinétique de cultures en milieu liquide ; la réalisation de la phylogénie des souches performantes par la technique des marqueurs AFLP.GRENOBLE1-BU Médecine pharm. (385162101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF