Search results for "Mphi"
showing 10 items of 626 documents
Pressure dependent arrangement of a protein in two-dimensional crystals specifically bound to a monolayer
1993
Abstract The arrangement of streptavidin bound to a biotinylated monolayer of a polymeric amphiphile at the air-water interface is studied as a function of lateral pressure or ligand density. Closely packed domains are observed by fluorescence microscopy. The arrangement of the protein in these domains is sensitively detected by X-ray reflectivity and an especially thorough data analysis yields the following: the distance of the protein from the air-monolayer interface varies with lateral pressure by 10 A; the interfaces involving the protein are much rougher than expected due to capillary waves; the electron density of the protein layer increases considerably on compression, which can be u…
Fifty-five-million-year history of oceanic subduction and exhumation at the northern edge of the Caribbean plate (Sierra del Convento mélange, Cuba)
2009
Petrological and geochronological data of six representative samples of exotic blocks of amphibolite and associated tonalite-trondhjemite from the serpentinitic melange of the Sierra del Convento (eastern Cuba) indicate counterclockwise P-T paths typical of material subducted in hot and young subduction zones. Peak conditions attained were 750 � C and 15 kbar, consistent with the generation of tonalitic partial melts observed in amphibolite. A tonalite boulder provides a U-Pb zircon crystallization age of 112.8 ± 1.1 Ma, and Ar ⁄ Ar amphibole dating yielded two groups of cooling ages of 106-97 Ma (interpreted as cooling of metamorphic ⁄ magmatic pargasite) and 87-83 Ma (interpreted as growt…
Critical Micelle Density for the Self-Assembly of Block Copolymer Surfactants in Supercritical Carbon Dioxide
1999
The parameters which influence the self-assembly of molecules in solution include the temperature and solvent quality, and this study illustrates the use of these variables to regulate the degree of association of block copolymer amphiphiles in highly compressible supercritical carbon dioxide. Small-angle neutron scattering (SANS) has been used to examine the association behavior of a block copolymer containing a CO2-phobic moiety, poly(vinyl acetate), and a CO2-philic block, poly(1,1-dihydroperfluoro-octylacrylate). By adjustment of the density of the medium through pressure and temperature profiling, the self-assembly can be reversibly controlled from unimers to core−shell spherical micel…
Amphiphilic Polyphenylene Dendron Conjugates for Surface Remodeling of Adenovirus 5
2020
Abstract Amphiphilic surface groups play an important role in many biological processes. The synthesis of amphiphilic polyphenylene dendrimer branches (dendrons), providing alternating hydrophilic and lipophilic surface groups and one reactive ethynyl group at the core is reported. The amphiphilic surface groups serve as biorecognition units that bind to the surface of adenovirus 5 (Ad5), which is a common vector in gene therapy. The Ad5/dendron complexes showed high gene transduction efficiencies in coxsackie‐adenovirus receptor (CAR)‐negative cells. Moreover, the dendrons offer incorporation of new functions at the dendron core by in situ post‐modifications, even when bound to the Ad5 sur…
Adsorption properties of soluble surface active stilbazium dyes at the air-water interface
2007
The adsorption behaviour of a homologous series of amphiphilic hemicyanines is studied at the air-water interface. The dyes exhibit an unusual, marked odd-even effect with respect to the standard free energy of adsorption and the minimum surface area demand. The reasons for such strong, hitherto unknown odd-even effect is not yet clear.
Temperature dependence of surface reorganization characteristics of amphiphilic block copolymer in air and in water studied by scanning force microsc…
2015
We have investigated the surface reorganization characteristics of a novel amphiphilic diblock copolymer, poly(acetic acid-2-(2-(4-vinyl-phenoxy)-ethoxy)-ethylester)-block-polystyrene (PAEES-b-PS), in response to varying interfaces from air to water and vice-versa at various temperatures. The surface reorganization characteristics of the block copolymer films was monitored by scanning force microscopy, in order to delineate the kinetically controlled morphological process of surface reorganization of a diblock copolymer, with a particular emphasis on the phase contrast signal which allowed the determination of local composition patterns of PAEES-b-PS at the surface. Upon heating a water-an…
Biological invasion and parasitism: invaders do not suffer from physiological alterations of the acanthocephalan Pomphorhynchus laevis.
2009
SUMMARYBiological invasions expose parasites to new invasive hosts in addition to their local hosts. However, local parasites are often less successful in infecting and exploiting their new hosts. This may have major consequences for the competitive ability of hosts, and finally on the fate of the parasite-host community. In Burgundy (Eastern France), the acanthocephalan parasite,Pomphorhynchus laevis, infects 2 amphipod species living in sympatry: the nativeGammarus pulexand the invasiveGammarus roeseli. WhileP. laevisaffects the behaviour and the immunity ofG. pulex,G. roeseliseems unaffected by the infection. In this study, we examined in detail the ability of the parasite to affect the …
Overestimation of the strength of size-assortative pairing in taxa with cryptic diversity: a case of Simpson's paradox.
2015
5 pages; International audience; Size-assortative pairing is one of the most common pairing patterns observed in nature and it probably occurs in many taxa with cryptic diversity. Observed patterns of size-assortative pairing in natural populations may thus be influenced by the co-occurrence of noninterbreeding cryptic groups of individuals living in sympatry. To quantify this potential bias, we sampled amphipods from the Gammarus pulex/Gammarus fossarum crustacean species complex in rivers containing two sympatric and morphologically cryptic groups, i.e. molecular operational taxonomic units (MOTUs). Within each river, MOTUs did not interbreed and differed in mean body size. We measured th…
Molecular markers and species delimitation: examples from the European batrachofauna
1996
AbstractMolecular techniques have revolutionised zoological systematics since the beginning of the seventies. Within the last twenty years numerous new amphibian species have been described in Europe almost solely on the basis of molecular data. This paper focuses on the use of molecular character state and genetic distance data for the delimitation of species. Case studies of European anurans (Discoglossus, water frogs of the genus Rana) are discussed in the framework of concurring species concepts to illustrate problems of assigning species status to divergent populations on the basis of molecular data.