Sol Gel Method

Preparation of mesoporous carbons by carbonizing organic gels was initiated by Pekala 101 . In his study, resorci-nol was condensed with formaldehyde in alkaline solution. A schematic diagram of the resorcinol-formaldehyde (RF) gelation mechanism is presented in Figure 30. Resorcinol was first substituted with hydroxymethyl group by a catalytic action of alkaline reagent. The products condensed into surface functionalized polymer clusters that cross-link to form a gel. Pekala and co-workers...

References

Tabor, The Hardness of Metals, Clarendon, Oxford, U.K., 1951. 2. J. B. Pethica, R. Hutchings, and W. C. Oliver, Phil. Mag. A 48, 593 (1983). 3. J. B. Pethica, in Ion Implantation into Metals (V. Ashworth, W. Grant, and R. Procter, Eds.), pp. 147-156. Pergamon, Oxford, U.K., 1982. 4. J. L. Loubet, J. M. Georges, J. M. Marchesini, and G. Meille, J. Tribology 106, 43 (1984). 5. D. Newey, M. A. Wilkens, and H. M. Pollock, J. Phys E Sci. Instrum. 15, 119 (1982). 6. M. F. Doerner and W. D. Nix, J....

Spherical Indenters

Spherical indentation was one of the first tests to determine the hardness of material. The Brinnel test is one of the most used to determine the hardness in a macroscale 1 . Francis 152 describes the deformation mechanisms of plastic spherical indentation, in an attempt to correlate the deformation mechanism to the pressure distribution under the indenter as a function of depth penetration. Spherical indentation has an interesting, and at the same time challenging, aspect the contact between...

Oral Application of Peptides using Nanoparticle Technology

In the clinical setting it would clearly be desirable to avoid having to inject nanoparticles but rather to make them available also as an oral method for drug delivery. The efficacy of drug delivery to the brain using dalargin-loaded poly(butylcyanoacrylate) nanoparticles after oral application was studied by Schroeder et al. 62 . Different nanoparticle formulations containing dextran 12,000, poloxamer 188, or polysorbate 85 as stabilizer loaded with dalargin were used. No additional coating...

Anisotropy Grain Size Effect and Indentation Size Effect

The study of very small-scale indentation has increased in the last few years. A considerable effort has been made in theoretical and practical aspects of this problem. At very low loads, nanoindentation is being used to understand the strain gradient plasticity and dislocation emission from the plastic region under the indenter. At larger scales of indentation, a number of models exist for plastic flow, but as experimental scales shrink, properties change then these models may not be...

Active Targeting

Active targeting is much more difficult to achieve. A number of possibilities exist. The first possibility that was employed was the alteration of the surface charge 287 . However, only a redistribution within the RES was obtainable. Another approach is the incorporation of small (1020 nm) magnetic Fe3O4 particles into the nanoparticle matrix 19, 19, 163-166, 174, 288-290 and the targeting by an external magnetic field. A localization in predesigned areas of rat tails was possible with magnetic...

Physical Adsorption

Physical adsorption is also one of the most effective modern tools for the characterization of the pore structure of mesoporous materials. Based on the shape of the isotherms and hysteresis loop, pore structures, including micro-, meso-, macropore, cylindrical pore, bottle-like pore, and so on, can be obtained. Pore size distribution, pore volume, and surface area can also be calculated. The probes used are usually Ar and N2 molecules. Because the atom diameter of Ar is smaller than that of N2,...

Material Intermixing

The furnace crystallization of sublayers from the low-temperature material in a-Ge and a-Si based a-MLs, requires quite high annealing temperatures (> 770 K for a-Ge H 1 and > 970 K for a-Si H 23 ). At these temperatures, undesired interdiffusion and alloying of the constituent materials may take place at ML interfaces. In certain studies on annealing of a-Ge H a-GeNx 101 , a-Ge H a-SiNx H 103 and a-Ge a-C 67 MLs alloying has not been observed. On the other hand, in a-Si H a-Ge H MLs 111 ,...

Mechanical Deagglomeration

Intimate contacts (up to almost the molecular level) of the nanoparticles with the polymeric matrix are a prerequisite for the design of well-functioning nanocomposites. To satisfy this condition, a thorough homogenization of the components must be obtained. Winkler et al. 125 developed a theory for the deagglomeration of ultrafine particle clusters in fluid systems, using the mechanical forces in a dispersion machinery. They showed that the probability that filler particles are dispersed in a...

Static Mixertubular Reactor Setup

As mentioned in the Introduction, a first step to overcoming the drawbacks of stirred tank reactors is the use of a continuous operating tubular reactor equipped with a static mixer 30 . The static mixer contains bow-tie shaped helical static mixing elements with clockwise and counterclockwise orientations with an internal width of 14.3 mm. BaTiO3 powder with a mean particle size of 80 nm and a specific surface area of 25 m2 g was synthesized using this static mixer-tubular reactor setup 31 ....

Aids

AIDS (acquired immune deficiency syndrome), an infection by the human immune deficiency viruses HIV 1 or 2, is mainly caused by infection of the T-helper cells and a subsequent breakdown of the immune system. While these cells die after infection, the virus can very well survive a number of other cells in the body, especially in macrophages. Since the macrophages easily take up nanoparticles, they are ideal delivery systems of anti-HIV drugs into these cells. The uptake of a variety of...

Membrane Processes

In the chemical process industry one often encounters the problem of separating a mixture in its components. Using membranes one can in principle carry out the majority of these separation processes and may complement or form Copyright 2004 by American Scientific Publishers All rights of reproduction in any form reserved. Encyclopedia of Nanoscience and Nanotechnology Edited by H. S. Nalwa Volume 7 Pages (47-82) v yWfHSrSzf,',' . MM WESEE& t OHM Figure 1. Scanning electron microscope (SEM)...

On Coating Characterization

A very large number of articles were written to describe the effect of the substrate in the determination of mechanical properties of thin films 22, 25, 96-105 . Several models were developed to describe the nanoindentation hardness and elastic modulus variation as a function of penetration to film thickness ratio 20, 23, 27, 106-109 . However, this problem continues without a satisfactory solution, and new models are expected to appear in the future. The major difficult factor for modeling the...

Separation by Solution Diffusion Process

To achieve separation on a molecular scale a relatively dense membrane is required. In this membrane the separation of components takes place based on differences in diffu-sivity and differences in solubility. At the feed side, the components are being dissolved in the membrane and transported by diffusion through the membrane with a driving force acting inside the membrane. At the permeate side, the components leave the membrane. Separation results from differences in the solubility of the...

Microjet Reactor

The principle of this reactor is relatively simple two reactant solutions were injected with high velocity up to 1,000 m s into a reaction chamber through a small nozzle between 100 and 1,000 m , and colloids are formed in the surrounding gas 65, 66 . Fine spray is generated, which results in a fast and homogenous mixing in the fine droplets. The powder precipitates in these fine droplets immediately. Additionally, a gas stream is injected into the reaction chamber, which allows cooling of...

Wafer Stepper Lithography

Laser Interference Lithography

In light projection lithography 49-51 an optical lens system is used to project the pattern of the mask onto the photo-lacquer layer contact-free technique . The blurring of the pattern is now only restricted to the size of the particles present on the photolacquer layer. The projection system often reduces the pattern of the mask between 1 and 10 times with respect to the projected pattern in the lacquer layer. The typical lacquer area that can be projected in one step is about 1-2 cm2. More...

Nanoengineered Biomembranes 31 Introduction

The research goal in biomembrane science is to study the function of natural biomembranes and to engineer new types of biomembrane materials on the nanometer scale 122124 . Natural biomembranes, in particular lipid bilayer cell membranes, have an important function in biological molecular exchange metabolism and signal transduction processes e.g., immune reactions, hormone detection of the living cell. Generally, these processes are mediated across the cellular membrane wall by a transmembrane...