Search results for "Colloid"
showing 10 items of 1288 documents
Metallic nanoparticle enrichment at low temperature, shallow CO2 seeps in Southern Italy
2012
We report on metal enrichment along a natural pH gradient owing to increased CO2 degassing at cold, shallow seeps of Vulcano Island in the Mediterranean Sea, off Sicily. We assessed composition of unfiltered and filtered seawater (<100 nm) along acidic zones ranging between ambient and pH 5, and showed that most seep derived elements are present as nanoclusters which then aggregate into larger colloids while mixing with ambient seawater along a pH gradient. Size and elemental composition of such naturally occurring nanoparticles assessed by modern characterisation methods were in good agreement with the results from conventional analytical methods. We provide analytical evidence for the pre…
Halloysite nanotubes-based nanocomposites for the hydrophobization of hydraulic mortar
2021
Abstract The treatment of stone surfaces for their protection from ageing caused by natural and anthropogenic effects is an open issue in materials development for Cultural Heritage. We thought interesting to verify the suitability of a modified cellulose biofilm filled with halloysite nanotubes as wax compatibilizers to design a protecting layer. A hydraulic mortar was selected as a stone prototype. To improve the physico-chemical properties of the covering layer, wax microparticles have been incorporated to control transport, consolidation and wettability features. In particular, different application protocols have been studied, namely brushing and spraying, to assess whether the propos…
Regeneration of the cell wall in protoplasts of Candida albicans. A cytochemical study using wheat germ agglutinin and concanavalin A.
1988
To assess the dynamics of synthesis of the wall by regenerating Candida albicans protoplasts deposition of chitin and mannoproteins were investigated ultrastructurally using wheat germ agglutinin conjugated with either horseradish peroxidase or colloidal gold, and Concanavalin A coupled to ferritin respectively. Freshly prepared protoplasts lacked wheat germ agglutinin receptor sites but after 1-2 h of regeneration, they were detected. After 4-5 h of regeneration, the cell wall showed a discrete structure which was only labelled with wheat germ agglutinin in thin sections. At this stage of regeneration the outermost layer of the wall was labelled with clusters of Concanavalin A-ferritin par…
Hyaluronan alkyl derivatives-based electrospun membranes for potential guided bone regeneration: Fabrication, characterization and in vitro osteoindu…
2020
Item does not contain fulltext The aim of the work was to determine the effects of the chemical functionalization of hyaluronic acid (HA) with pendant aliphatic tails at different lengths and free amino groups in terms of chemical reactivity, degradation rate, drug-eluting features, and surface properties when processed as electrospun membranes (EM) evaluating the osteoinductive potential for a possible application as guided bone regeneration (GBR). To this end, a series of HA derivatives with different aliphatic tails (DD-Cx mol% ≈ 12.0 mol%) and decreasing derivatization of free amino groups (DD(EDA) mol% from 70.0 to 30.0 mol%) were first synthesized, namely Hn. Then dexamethasone-loaded…
Research report: Interactions between toxic fatty acids for yeasts and colloids, cellulose and yeast ghost using the equilibrium dialysis method in a…
1997
Abstract The capacity of different materials (yeast walls, colloids and cellulose) to bind octanoic acid and decanoic acid was investigated in a model wine. The interactions between these toxic fatty acids and the soluble or insoluble material was shown using the equilibrium dialysis method. Yeast walls adsorb decanoic acid and to a lesser extent octanoic acid which confirms previous results. In comparison, colloids from both grape or yeast weakly bind decanoic acid and do not significantly bind octanoic acid. No interactions between cellulose and fatty acid were observed. According to the yeast wall composition, lipids seem to play a key role for binding. With regards to our results, the e…
Application of small angle neutron scattering to micellar fluids
1990
Abstract In this paper we present a short overview of the application of small angle neutron scattering (SANS) to micellar fluids. In the first part of the paper a general expression of the scattering equation is derived, with particular emphasis on the approximations involved and on their practical consequences. In the second part of the paper we present six selected test cases (such as mono- and polydisperse fluids, critical fluids, shapes other than spherical, etc.) taken from our own work, to demonstrate the kind of analysis performed in each case to extract the information from SANS data.
Thermodynamical aspects regarding the formation of self-assembly decylpolyglucoside structures
2005
In this study, we used a generalized form of a recently reported parametrization based on the differential geometry and the thermodynamics of dispersed systems to ascertain the capability of decylpolyglucoside alone or in association with cholesterol to form vesicle structures (niosomes). The theoretical calculation of the energy balance involved in the vesicles formation was carried out using values of the critical concentration of formation (ccf), surface tension and the molar surface area of the non-ionic surfactant. Furthermore, in order to confirm the theoretical results found in this work, we prepared and characterized vesicles made with decylpolyglucoside and cholesterol. The vesicle…
Phenylene motion in polycarbonate and polycarbonate/additive mixtures
1987
Pulsed deuteron NMR line shapes have been analysed to characterize type and time scale of the phenylene group motion in glassy bisphenol-A polycarbonate. The motional mechanism involvesπ-flips about theC1C4 axis augmented by small angle fulctuations about the same axis, reaching a rms amplitude of ±35‡ at 380 K. The distribution of correlation times for theπ-flips is heterogeneous in nature and can be described either by a log-Gaussian or an asymmetric distribution with a more rapid decay at high correlation times comparable to the Williams-Watts distribution. From both distributions essentailly the same mean activation energy of 37 kJ/mol is obtained, whereas the temperature dependent widt…
Layer-Wise Discontinuous Galerkin Methods for Piezoelectric Laminates
2020
In this work, a novel high-order formulation for multilayered piezoelectric plates based on the combination of variable-order interior penalty discontinuous Galerkin methods and general layer-wise plate theories is presented, implemented and tested. The key feature of the formulation is the possibility to tune the order of the basis functions in both the in-plane approximation and the through-the-thickness expansion of the primary variables, namely displacements and electric potential. The results obtained from the application to the considered test cases show accuracy and robustness, thus confirming the developed technique as a supplementary computational tool for the analysis and design o…
Direct Writing on Copper Ion Doped Silica Films by Electrogeneration of Metallic Microstructures
2017
International audience; A facile and rapid localized electrochemical reduction of colloid copper particles is proposed using the scanning electrochemical,microscope (SECM), technique. In this purpose, thin films of composite silica :glass containing copper salts were prepared by the sol-gel method via the dip coating technique. Acid-catalyzed tetraethylorthosilane (TEOS) solutions charged with copper nitrate were used as precursors. This one-pot experiment can be performed in mild conditions. The localized generation of copper metallic nanostructures on silica film has been performed by electroreduction of methyl viologen on an ultramicroelectrode (UME). The UME generates reducing species, …