117,346 research outputs found
Mi-carême : polka : piano 2 mains / par E. Becucci ; [ill. par] L. Burret
No full textTitre uniforme : Becucci, Ernesto (1845-1905). Compositeur. [Mi-Carême. Piano]Polkas (piano) -- +* 1800......- 1899......+:19e siècle:Piano, Musique de -- +* 1800......- 1899......+:19e siècle
A pouffer de rire : polka : piano / par E. Becucci ; [ill. par] L. Denis
No full textTitre uniforme : Becucci, Ernesto (1845-1905). Compositeur. [À pouffer de rire]Polkas (piano) -- +* 1800......- 1899......+:19e siècle:Piano, Musique de -- +* 1800......- 1899......+:19e siècle
A pouffer de rire : polka : [piano] quatre mains / par E. Becucci ; [ill. par] L. Denis
No full textTitre uniforme : Becucci, Ernesto (1845-1905). Compositeur. [À pouffer de rire]Polkas (piano, 4 mains) -- +* 1800......- 1899......+:19e siècle:Piano, Musique de (4 mains) -- +* 1800......- 1899......+:19e siècle
Probing membrane permeabilization by the antibiotic lipopeptaibol trichogin GA IV in a tethered bilayer lipid membrane
No full textAbstractThe lipopeptaibol trichogin GA IV (TCG) can be incorporated in the lipid bilayer moiety of a mercury-supported tethered bilayer lipid membrane (tBLM) at a non-physiological transmembrane potential of about −240mV, negative on the trans side of the bilayer. Once incorporated in the tBLM, TCG is stable over the range of physiological transmembrane potentials and permeabilizes the membrane at transmembrane potentials negative of −80÷−90mV. The chronocoulometric behavior is consistent with a kinetics of nucleation and growth of bundles of TCG building blocks with ion-channel properties. The TCG building blocks also permeabilize the lipid bilayer, albeit at more negative transmembrane potentials, and can be tentatively regarded as dimers of aligned TCG helical monomers. The cyclic voltammograms of tBLMs incorporating TCG point to a voltage-gated behavior of the TCG channel, similar to that exhibited by the peptaibol alamethicin
Au25(SCnH2 n+1)18 Clusters in Biomimetic Membranes: Role of Size, Charge, and Transmembrane Potential in Direct Membrane Permeation
No full textGold nanoclusters and nanoparticles are promising materials for applications in nanomedicine, and therefore, understanding their interaction with cell membranes is of particular importance. A series of neutral and anionic Au25(SCnH2n+1)18 monolayer protected clusters (MPCs) (briefly, Cn0 and Cn- clusters), was embedded into two types of biomimetic membranes supported by mercury electrodes. The first was a dioleoylphosphatidylcholine (DOPC) self-assembled monolayer (SAM), whereas the second was a tethered bilayer lipid membrane (tBLM) obtained by first anchoring a thiolipid monolayer to the mercury surface and then self-assembling a DOPC monolayer on top of it. The diameter of these clusters, from 1.7 to 2.7 nm depending on the thiolate ligand, is smaller than the thickness of biomembranes and biomimetic membranes. Both neutral and anionic Au25(SCnH2n+1)18 MPCs can penetrate the lipid bilayer moiety of the tBLM, without disrupting it; in particular, anionic Au25 clusters require positive transmembrane potentials to do so. Neutral Au25 clusters exchange one electron with mercury in a DOPC SAM, where they can come in contact with the mercury surface, whereas they are prevented from doing so at the tBLM because of their inability to cross the hydrophilic chain separating the lipid bilayer moiety from the mercury surface. The potential of these Au25 clusters to penetrate directly the plasma membrane is particularly convenient for targeted drug delivery. They are highly stable, biocompatible, and catalytic, and their uniform size is of importance in nanomedicine. Moreover, they may induce an efficient energy transfer to 3O2, allowing applications in radiotherapy and antimicrobial activity.
A procedure for estimating the surface dipole potential of monolayers adsorbed on electrodes
No full textEffect of a Strong Interfacial Electric Field on the Orientationof the Dipole Moment of Thiolated Aib-Oligopeptides Tetheredto Mercury on Either the N- or C-Terminus
No full textFour oligopeptides consisting of a sequence of R-aminoisobutyric acid (Aib) residues, thiolated
at either the N- or C-terminus by means of a -(CH2)2-SH anchor, were self-assembled on mercury, which
is a substrate known to impart a high fluidity to self-assembled monolayers (SAMs). The surface dipole
potential of these peptide SAMs was estimated in 0.1 M KCl aqueous solution at a negatively charged
electrode, where the interfacial electric field is directed toward the metal. To the best of our knowledge,
this is the first estimate of the surface dipole potential of peptide SAMs in aqueous solution. The procedure
adopted consisted in measuring the charge involved in the gradual expansion of a peptide-coated mercury
drop and then combining the resulting information with an estimate of the charge density experienced by
diffuse layer ions. The dipole moment of the tethered thiolated peptides was found to be directed toward
the metal, independent of whether they were thiolated at the C- or N-terminus. This result was confirmed
by the effect of these SAMs on the kinetics and thermodynamics of the Eu(III)/Eu(II) redox couple. The
combined outcome of these studies indicates that a strong interfacial electric field orients the dipole moment
of peptide SAMs tethered to mercury, even against their “natural” dipole moment
Incorporation of channel-forming peptides in a Hg-supported lipid bilayer
No full textThe channel-forming peptides gramicidin and alamethicin were incorporated in a mercury-supported lipid bilayer composed of a tethered thiolipid monolayer with a self-assembled dioleoylphosphatidylcholine monolayer on top of it. The thiolipid consists of a hexapeptide chain with a high tendency to form a 310-helical structure, which terminates at the N-terminus end with a sulfydryl group for anchoring to the metal while the C-terminus end is covalently linked to the polar head of dimyristolylphosphatidylethanolamine. The hexapeptide moiety has two triethyleneoxy side chains that impart a satisfactory hydrophilicity and are intended to keep the anchored thiolpeptide chains sufficiently apart, so as to accommodate water molecules and inorganic ions and to create a suitable environment for the incorporation of integral proteins. Changes in the conductance of this biomimetic membrane following the incorporation of gramicidin and alamethicin were detected by impedance spectroscopy. The surface dipole potential of the hexapeptide chain and the transmembrane potential of the lipid bilayer were estimated by using a simple electrostatic model of the mercury|solution interphase
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Testing new peat-free substrate mixtures for the cultivation of perennial herbaceous species: A case study on Leucanthemum vulgare Lam
No full textOne of the major challenges for nursery growers is replacing peat with more sustainable materials that may also represent a worthy strategy to recycle organic refuse. Among organic matrices, coconut coir dust, green compost, and stabilized wood fibre are considered promising alternative to peat because of their suitable physical-chemical characteristics. These matrices were used to prepare substrate mixtures designed to achieve physical characteristics similar to those of the standard peat-based substrates usually adopted by growers (peat:pumice, 70:30 v v−1). An experiment was carried out in open field with Leucanthemum vulgare Lam., a plant species that could be used for ecological restoration, by using both the native and the ornamental variety of the same species (L. vulgare cv. ‘Filigran’), the latter as test plants. Six different growing media were tested: (i) peat:pumice 70:30 v v−1 (PP), used as commercial control; (ii) coconut coir dust:pumice, 70:30 v v−1 (CP); (iii) coconut coir dust:green compost 55:45 v v−1 (CGC); (iv) coconut coir dust:stabilized wood fibre 60:40 v v−1 (CW); v) green compost:stabilized wood fibre 30:70 v v−1 (GCW) and, (vi) coconut coir dust:green compost:stabilized wood fibre 40:30:30 v v−1 (CGCW). Plant biomass, biometric parameters, plant and matrix/substrate mineral content, and mineral composition of water drained out from pots were measured as main performance indicators of plants and growing media. All the tested peat-free substrates, with the exception of GCW, adequately supported plant growth and quality. Moreover, CP and CGCW improved some of the investigated biomass and biometric parameters compared with the control treatment. Substrates containing green compost were found to improve plant nutrition, because of the high availability of mineral elements in the raw material
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