Search results for "DSO"
showing 10 items of 1609 documents
Real-time microfluorescence studies of Langmuir-Blodgett deposition: Monolayer adsorption and desorption
1990
Abstract Observations of the meniscus region in a typical Langmuir-Blodgett configuration are obtained using fluorescence microscopy. Studies of the meniscus position as a function of pH demonstrate that the meniscus height increases upon charging the monolayer owing to the repulsive interaction between monolayer and substrate surfaces. Through the correspondence between meniscus height and contact angle the adhesion forces between monolayer and substrate as a function of monolayer charge are assessed. The phenomenon of desorption upon resubmerging a deposited film is described and it is shown that the meniscus height at the onset of the desorption is greater for higher pH.
Pore Size Analysis of MCM-41 Type Adsorbents by Means of Nitrogen and Argon Adsorption
1998
Methods of nonlocal density functional theory (NLDFT), proposed recently for predictions of adsorption equilibrium and calculations of pore size distributions in micro- and mesoporous materials, were tested on reference MCM-41 materials. Five newly synthesized MCM-41 adsorbents with presumably uniform pore channels varying from 32 to 45 Å were characterized by X-ray diffraction (XRD), nitrogen adsorption at 77 K, and argon adsorption at 77 and 87 K. New sets of intermolecular interaction parameters of the NLDFT model for N2 and Ar adsorption on MCM-41 were determined. The parameters were specified to reproduce the bulk liquid-gas equilibrium densities and pressures, liquid-gas interfacial t…
Electrochemical Interfaces: At the Border Line
2002
The sections in this article are Introduction Basic Concepts Thermodynamics of Electrified Interfaces Classical Models of Electrified Interfaces Helmholtz Model Gouy–Chapman–Stern–Grahame Model Diffuse and Compact Layer Properties Grahame Model in Comparison with Capacitance Data for Liquid Electrodes Compact Layer Properties Manifestations of the Diffuse Layer in Kinetics of Electrode Reactions Electrokinetic Phenomena Solid Electrodes: Effects of Polycrystallinity and Surface Roughness “Uniform” Model of Solid Electrodes. Surface Roughness Crystallographic Inhomogeneity Effects for Solid Electrode Surfaces EDL Structure for NonUniform Electrode Surfaces Surface Roughness Effect on the Dif…
Mixed Ligand Shell Formation upon Catechol Ligand Adsorption on Hydrophobic TiO2 Nanoparticles
2019
Modifying the surfaces of metal oxide nanoparticles (NPs) with monolayers of ligands provides a simple and direct method to generate multifunctional coatings by altering their surface properties. T...
Exceptional affinity of nanostructured organic-inorganic hybrid materials towards dioxygen: confinement effect of copper complexes
2007
We report the exceptional reactivity towards dioxygen of a nanostructured organic-inorganic hybrid material due to the confinement of copper cyclam within a silica matrix. The key step is the metalation reaction of the ligand, which can occur before or after xerogel formation through the sol-gel process. The incorporation of a Cu(II) center into the material after xerogel formation leads to a bridged Cu(I)/Cu(II) mixed-valence dinuclear species. This complex exhibits a very high affinity towards dioxygen, attributable to auto-organization of the active species in the solid. The remarkable properties of these copper complexes in the silica matrix demonstrate a high cooperative effect for O(2…
Growth of human cells on a non-woven silk fibroin net: a potential for use in tissue engineering.
2003
We have examined a novel biomaterial consisting of a non-woven fibroin net produced from silk (Bombyx mori) cocoons for its ability to support the growth of human cells. Various human cells of different tissue and cell types (endothelial, epithelial, fibroblast, glial, keratinocyte, osteoblast) were examined for adherence and growth on the nets by confocal laser microscopy after staining of the cells with calcein-AM and by electron microscopy. All the cells readily adhered and spread over the individual fibers of the nets. Most of the cells were able to grow and survive on the nets for at least 7 weeks and growth not only covered the individual fibers of the net but generally bridged the ga…
Investigation of characterizing methods for the microstructure of cement
2002
Volumetric, gravimetric, calorimetric, flow methods, mercury porosimetry and laser granulometry were used to investigate the surface structure and the sorption behavior of industrial cements and hydrated cement paste. The suitability of the measuring methods is assessed.
Surface Relaxivity of Cement Hydrates
2014
Numerous aspects of the physical chemistry of colloidal systems are conditioned by the solid–liquid interface, and this is also the case for hydrated cement systems. Estimating the surface area is thus essential for studying the kinetics of cement hydration and admixture adsorption. Proton nuclear magnetic resonance (NMR) relaxation techniques have already proven useful for this objective, but, for hydrating cements at early ages, it is necessary to know the surface relaxivities of all of the individual phases present to correctly interpret the relaxation data. This paper reports the results of a comparison of NMR relaxometry and Brunauer–Emmett–Teller gas adsorption measurements on various…
Engineering Photocatalytic Cements: Understanding TiO2 Surface Chemistry to Control and Modulate Photocatalytic Performances
2010
The present work addresses the aggregation/dispersion properties of two commercial titanias for application as photocatalysts in concrete technology. A microsized m-TiO2 (average particle size 153.7 ± 48.1 nm) and a nanosized n-TiO2 (average particle size 18.4 ± 5.0 nm) have been tested in different ionic media (Na+, K+, Ca2+, Cl−, SO42−, synthetic cement pore solution) at different pHs and in real cement paste specimens. Results highlighted that ion–ion correlations play a fundamental role in TiO2 particles aggregation in the cement environment. A particle aggregation model derived from TiO2 surface chemistry is proposed here and used to justify such aggregation phenomena in real cement pa…
Changes in Cement Paste and Mortar Fluidity after mixing induced by PCP: A parametric study
2006
International audience; The interaction mechanism between polycarboxylate-type superplasticizer (PCP) and cement hydration is not fully understood and incompatibilities between concrete and additive are sometimes observed. In some cases, the fluidity tends to increase (“overfluidification”) few minutes after mixing. This is a problem because the overfluidification leds to bleeding of the concrete which could be critical on job site. Our study consisted first in highlighting the phenomenon of “over-fluidification” by slump flow tests on mortar. Next, the time evolution of the rheological behaviour of cement pastes in the presence of PCP was analysed thanks to a rheometry protocol in order to…