Search results for "SITES"

Carbon nanotubes-based nanohybrids for multifunctional nanocomposites

2017

In the present work, nano-hybrids based on carbon nanotubes (CNTs) bearing immobilized, either through covalent linkage and physical absorption, commercial anti-oxidant molecules have been formulated and used as nanofillers in Ultra High Molecular Weight Polyethylene (UHMWPE), aiming at preparing multifunctional nanocomposites. The effective immobilization of the anti-oxidant molecules has been probed by spectroscopic and thermogravimetric analyses. The study of the morphology and the rheological behaviour of the nanocomposites show that the immobilization of anti-oxidant molecules onto the CNTs surface is beneficial for the state of the polymer/nanoparticles interfacial region. Additionall…

Facile Fabrication of Natural Polyelectrolyte-Nanoclay Composites: Halloysite Nanotubes, Nucleotides and DNA Study

2020

Complexation of biopolymers with halloysite nanotubes (HNTs) can greatly affect their applicability as materials building blocks. Here we have performed a systematic investigation of fabrication of halloysite nanotubes complexes with nucleotides and genomic DNA. The binding of DNA and various nucleotide species (polyAU, UMP Na2, ADP Na3, dATP Na, AMP, uridine, ATP Mg) by halloysite nanotubes was tested using UV-spectroscopy. The study revealed that binding of different nucleotides to the nanoclay varied but was low both in the presence and absence of MgCl2, while MgCl2 facilitated significantly the binding of longer molecules such as DNA and polyAU. Modification of the nanotubes with DNA an…

Silica aerogel–metal composites produced by supercritical adsorption

2010

Abstract Silica aerogel has been loaded with ruthenium acetyl acetonate (Ru(acac) 3 ) by adsorption from supercritical carbon dioxide. Adsorption isotherms and kinetics were measured at different pressures and temperatures. The properties of impregnated aerogel were obtained by optical and electron microscopy (SEM), X-ray microanalysis (EDX) and thermogravimetric analysis (TGA). Results showed that Ru(acac) 3 can be uniformly dispersed into the aerogel up to 5 wt%. Moreover, precursor loading is controllable by properly changing operating conditions. The adsorbed metallorganic compound has been reduced to elemental ruthenium by heat treatment without inducing degradation and morphological c…

Three-dimensional analysis of load transfer micro-mechanisms in fibre/matrix composites

2009

International audience; This study gives a detailed analysis of load distributions around fibre breaks in a composite. In contrast to other studies reported in the literature, the analysis considers different configurations of composite damage from the failure of a few to the failure of many fibres. The model considers three types of matrix behaviours (elastic, elastic–plastic and viscoelastic) with or without debonding at the broken fibre/matrix interface. In this way, the usual limitations of the finite element approach are overcome so as to take into account the number and interactions of broken fibres whilst maintaining an evaluation of the various fields (stresses in particular).

Total Synthesis of the Glycopeptide Recognition Domain of the P-Selectin Glycoprotein Ligand 1

2008

Ferricytochrome c encapsulated in silica hydrogels: correlation between active site dynamics and solvent structure.

2003

Ferricytochrome c encapsulated in silica hydrogels has been prepared by the sol-gel technique following, with some modifications, the procedure originally developed by Ellerby et al. (Science 255 1113 (1992)). A suitable preparation of hydrogels enables having both 'wet' and 'dry' samples. Wet samples have a high water content: as the temperature is lowered below approximately 260 K, water freezes and the samples crack. On the contrary, dry samples have a low water content (hydration h approximately equal 0.35): in these conditions water does not freeze even at cryogenic temperatures and the samples remain transparent and non-cracking. The dynamics of ferricytochrome c and its dependence on…

Inhibition of giant cell formation by compound 48/80 after infection with herpesvirus hominis

1974

Choline kinase has been found to be a soluble enzyme with a molecular weight of 105,000 in the cytoplasm of primary rabbit kidney cells. It has been purified 150-fold. It was investigated whether the inhibiting effect of Cpd 48/80 on virus-induced giant cell formation is due to interference with this enzyme. Cpd 48/80-dimer was shown to inhibit the choline kinase activityin vitro without a concomitant inhibition of giant cell formation. Likewise, another competitive inhibitor of choline kinase, purinyl-6-histamine, does not prevent giant cell formation. This finding suggests that there is no correlation between choline kinase activity and giant cell formation.

Follow-up trends of parasite community alteration in a marine fish after the Prestige oil-spill: shifting baselines?

2008

This study evaluates the follow-up trends in the composition and structure of the parasite communities in the marine sparid Boops boops after the Prestige oil-spill. A total of 400 fish comprising 11 seasonal samples was analyzed from three impacted localities on the Atlantic coast of Spain. A large number of parasite species was recovered only after the spill thus suggesting a substantial alteration of the marine food webs. Post-spill communities exhibited higher richness and abundance due to the significant changes in the abundance of the common species, the latter indicating accelerated parasite transmission rates. Multivariate analyses at two nested scales detected a directional trend i…

Short‐term hypoxia promotes vascularization in co‐culture system consisting of primary human osteoblasts and outgrowth endothelial cells

2019

Prevascularization of tissue constructs before implantation has been developed as a novel and promising concept for successful implantation. Since hypoxia might induce angiogenesis, we have investigated the effects of hypoxic treatment on vascularization by using co-cultures of primary human osteoblasts (POBs) and outgrowth endothelial cells. Our results show that: (a) repeated short-term hypoxia (2% O2 for 8 hr), not long-term hypoxia (2% O2 for 24 hr), over 1 or 2 weeks, significantly enhances microvessel formation in co-cultures; (b) sustained hypoxia, not short-term or long-term hypoxia, causes cytotoxicity in mono- and co-cultures; (c) the expression of some angiogenic and inflammatory…

An analytical solution for multilayered beams subjected to ends loads

2014

An alternative model for multilayered beams undergoing axial, shear and bending loads applied at the beam's ends is developed. It is based on a layer-wise kinematics, which inherently fulfills the equilibrium equations at layer level and the interface continuity conditions. This kinematics is suitably expressed by introducing a set of generalized variables representative of the beam midline displacement field, which become the primary variables of the problem governing equations. As a consequence, the proposed beam model exhibits the computational characteristics of an equivalent single layer model and possesses the accuracy of layer-wise beam theories, as well. Closed form solutions for di…