Search results for "colloid"
showing 10 items of 1288 documents
DNA Block Copolymer Micelles – A Combinatorial Tool for Cancer Nanotechnology
2008
Selective drug targeting of a specific organ or tissue is a challenging task. This holds especially true for chemotherapeutic cancer treatment because most of the available anticancer agents cannot distinguish between cancerous and healthy cells, leading to systemic toxicity and undesirable side effects. One effective approach to address this problem is the application of polymeric nanoparticles equipped with targeting units for tumor-specific delivery. For instance dendrimers, highly branched macromolecules, can be equipped with targeting units as well as with anticancer drugs because of their large number of surface functionalities. Amphiphilic block copolymers, which self-assemble in dil…
Physicochemical processes in blanket ceramic materials
2003
Abstract Effect of external magnetic field (MF) on important physicochemical processes in ceramic blanket materials, the Li4SiO4 (FZK) and Li2TiO3 (CEA) ceramic pebbles, was studied. Stoichiometric amounts of the radiation-induced defects (RD) of the electron and hole type form at radiolysis of the ceramic materials. Colloid lithium forms only in Li4SiO4 under irradiation at the temperature 423–473 K and the dose 10–20 MGy. The magnetic field increases the radiolysis efficiency by 20–25% in both materials. The efficiency of formation of RD decreases with the increasing temperature of irradiation. Complete recombination of RD takes place at 873 K. The magnetic field retards the tritium relea…
Non-equilibrium melting of colloidal crystals in confinement
2009
International audience; We report on a novel and flexible experiment to investigate the non-equilibrium melting behaviour of model crystals made from charged colloidal spheres. In a slit geometry polycrystalline material formed in a low salt region is driven by hydrostatic pressure up an evolving gradient in salt concentration and melts at large salt concentration. Depending on particle and initial salt concentration, driving velocity and the local salt concentration complex morphologic evolution is observed. Crystal-melt interface positions and the melting velocity are obtained quantitatively from time resolved Bragg- and polarization microscopic measurements. A simple theoretical model pr…
Rapid one-pot propargylamine synthesis by plasmon mediated catalysis with gold nanoparticles on ZnO under ambient conditions
2013
Surface plasmon excitation of gold nanoparticles on ZnO in the presence of an aldehyde, an amine and phenylacetylene led to rapid and selective formation of propargylamines with good yields (50-95%) at room temperature. Plasmon mediated catalysis is the best available route for this ternary coupling.
Detaching Microparticles from a Liquid Surface.
2018
The work required to detach microparticles from fluid interfaces depends on the shape of the liquid meniscus. However, measuring the capillary force on a single microparticle and simultaneously imaging the shape of the liquid meniscus has not yet been accomplished. To correlate force and shape, we combined a laser scanning confocal microscope with a colloidal probe setup. While moving a hydrophobic microsphere (radius 5-10 μm) in and out of a 2-5 μm thick glycerol film, we simultaneously measured the force and imaged the shape of the liquid meniscus. In this way we verified the fundamental equations [D. F. James, J. Fluid Mech. 63, 657 (1974)JFLSA70022-112010.1017/S0022112074002126; A. D.…
Colloidal plasmonic back reflectors for light trapping in solar cells.
2014
A novel type of plasmonic light trapping structure is presented in this paper, composed of metal nanoparticles synthesized in colloidal solution and self-assembled in uniform long-range arrays using a wet-coating method. The high monodispersion in size and spherical shape of the gold colloids used in this work allows a precise match between their measured optical properties and electromagnetic simulations performed with Mie theory, and enables the full exploitation of their collective resonant plasmonic behavior for light-scattering applications. The colloidal arrays are integrated in plasmonic back reflector (PBR) structures aimed for light trapping in thin film solar cells. The PBRs exhib…
Effect of latex on surface structure and wetting of pigment coatings
2010
Abstract The amount and type of latex binder has a significant effect on both the structure and chemical properties of pigment coatings, which affects critical surface properties, e.g., gloss, ink setting rate via liquid absorption, and spreading properties. Increased knowledge is required for improved optimization in practical applications of pigment coating layers. To this end, the effect of binder amount for two different styrene–butadiene latices in kaolin pigment coatings on a base paper was studied, by measuring the surface topography, surface chemistry, and liquid absorption of these coatings. The topography was thoroughly analyzed from nanometer to millimeter length scales by atomic…
MCM-41, MCM-48 and related mesoporous adsorbents: their synthesis and characterisation
2001
MCM-41, MCM-48, MCM-41 analogue materials and disordered silica xerogels were compared with respect to their long range and short range order, their specific surface area, pore structure and pore structural parameters, pore wall thickness and their surface hydroxyl group concentration. Based on X-ray diffraction data it could be seen that the degree of long range order decreased in the order MCM-41>MCM-48>MCM-41 analogues >amorphous silica xerogels. The particle porosity and pore wall thickness increased in the same sequence such that MCM-41 analogues and amorphous silica xerogels were more stable towards water and water vapour. The concentration of the surface hydroxyl groups increased whe…
Selective hydrogenation of nitroderivatives over Au/TiO2/UVM-7 composite catalyst
2020
Abstract Hydrogenation of nitroderivatives (4-nitrostyrene or 7-nitro-1-tetralone) was performed using as support a silica mesoporous material with high specific surface area (1091 m2/g) and a bimodal pore size distribution (UVM-7). Gold and/or TiO2 were deposited inside the pores of this support with the aim to achieve high activity and selectivity for this reaction. The morphology and structure of the powders have been characterized by adsorption-desorption isotherms, XRD, TEM, STEM-HAADF, XPS and ATR-FTIR. Structural characterizations shown differences between the catalysts with and without titania. The presence of TiO2 provides a better size distribution of the spherical gold nanopartic…
Stable anchoring of dispersed gold nanoparticles on hierarchic porous silica-based materials
2010
The nanometric organization of MOx (M = Co, Zn, Ni) domains partially embedded inside the mesoporous silica walls but accessible to the pore voids, which is achieved through a simple one-pot surfactant-assisted procedure, define optimal anchors for the nucleation and growth of gold nanoparticles, which in turn favours an exceptional thermal stability for the final Au-supported materials. As silica support we have selected a UVM-7 silica having a highly accessible architecture defined by two hierarchic pore systems. The combination of nanometric pore length, tortuous mesopores and MOx inorganic anchors favours the stability of the final Au/CoOx-UVM-7 nanocomposites.