Hollow channel

Fig. 9 Schematic representation of three approaches to generate nanoporous and meso-porous materials with block copolymers, a Block copolymer micelle templating for mesoporous inorganic materials. Block copolymer micelles form a hexagonal array. Silicate species then occupy the spaces between the cylinders. The final removal of micelle template leaves hollow cylinders, b Block copolymer matrix for nanoporous materials. Block copolymers form hexagonal cylinder phase in bulk or thin film state. Subsequent crosslinking fixes the matrix hollow channels are generated by removing the minor phase, c Rod-coil block copolymer for microporous materials. Solution-cast micellar films consisted of multilayers of hexagonally ordered arrays of spherical holes. (Adapted from [33])...

Neurons maintain electrical potential across a membrane by pumping sodium ions from their inner hollow channels. 

Urea has the remarkable property of forming crystalline complexes or adducts with straight-chain organic compounds. These crystalline complexes consist of a hollow channel, formed by the crystallized urea molecules, in which the hydrocarbon is completely occluded. Such compounds are known as clathrates. The type of hydrocarbon occluded, on the basis of its chain length, is determined by the temperature at which the clathrate is formed. This property of urea clathrates is widely used in the petroleum-refining industry for the production of jet aviation fuels (see Aviation and other gas-turbine fuels) and for dewaxing of lubricant oils (see also PETROLEUM, REFINERY PROCESSES). The clathrates are broken down by simply dissolving urea in water or in alcohol. 

Electrical trees consist of visible permanent hollow channels, resulting from decomposition of the material, and show up clearly in polyethylene and other translucent solid dielectrics when examined with an optical microscope. Fresh, unstained water trees appear diffuse and temporary. Water trees consist of very fine paths along which moisture has penetrated under the action of a voltage gradient. Considerable force is required to effect this... 

The transmission electron microscopy of the pyrolysis products (Fig. 4) shows the presence of carbon fibers having the outer diameter of 20-200 nm, and some of them, the thinnest, having hollow channel inside. The most of fibers are a kind of tightly curled helices or "plumed clouds". 

Nylon. In 1939 the DuPont Company introduced the first truly synthetic textile fiber. Dr. Wallace Carothers invented nylon as a result of his basic research into polymer science. Chemically, nylon is a polyamide fiber. The two major types of nylon polymer are used in textiles type 6,6 which is made by using hexam-ethylene glycol and adipic acid, and type 6, which is made by polymerizing e-caprolactam. Nylon fibers are made by melt-spinning the molten polymer. The result is a continuous filament fiber of indeterminate length. It is spun in many deniers, with its diameter varying from 10 to 50 microns. The cross-section usually is round, trilobal, or square with hollow channels when used as carpet fiber. 

Subsequently, Stamm and coworkers [184-186] used PS-fo-P4VP diblock copolymers in combination with 2-(4-hydroxybenzeneazo)benzoic acid (HABA, Scheme 7). Thin films with cylindrical nanodomains of the P4VP-HABA complexes in a PS matrix were produced. The ahgnment of the cylinders could be switched upon exposure to vapors of different solvents from parallel to perpendicular (Fig. 25). Extraction of HABA resulted in nanoporous membranes with hollow channels of 8 nm (Fig. 26). The channels were filled with Ni clusters via the electrodeposition method to fabricate an ordered array of metalhc nanodots. 

Besides hollow channels, porous lamellar structures have also been prepared via the comb-shaped supramolecules route. PS-fo-P4VP diblock copolymers were taken that, together with zinc dodecylbenzenesulfonate [187],... 

The morphology of the surface of the oxide solid mask undergoes modifications due to the physical effect of particles bombarding the surface. In the SEM microphotograph of cleavage, we observed the presence of hollow channels in the aluminum oxide mask and pits in silicon. From the data it follows that, at the chosen mode of etching of the structure, the accelerated neutral atoms of argon completely removed the barrier film layer of silicon oxide from the bottom part of the aluminum oxide bulk, and the surface layer of silicon substrate was etched. 

During irradiation by swift ions, latent ion tracks are formed along the path of the ions. After irradiation, the material is subjected to chemical treatment leading to formation of the hollow channel from the latent ion track. The size and shape of the etched ion track is determined by the chemical processing. The etch process depends on the energy deposition density of the ion along its path, on the radiation... 

Composite board, inside the hollow channel Composite board after extensive weathering, upper surface... 

Figure 15.14 A GeoDeck Mahogany board temperature at three different points of the board in the course of one cycle of weathering (Q-Sun 3000, UV filter Daylight, UV sensor 340, 0.35 W/m, black panel 63°C, ASTM G155-97, Cycle 1 Light 1 42, Light + Spray 0 18). The first bar in each triple cluster—the top surface of the board the second bar—the inner upper surface of the hollow channel the third bar—the bottom surface of the board.

Porous anodic alumina (PAA) has a wide application in protection and decorative coating, electrolytic capacitors, host matrix for metal nanowire and carbon nanotube deposition. PAA consists of close packed near hexagonal cells with hollow channel at each cell axis. 

The carbon nanotubes possess such properties as high conductivity, excellent strength and stiffness, and chemical inermess. CNTs also show unusual electronic characteristics that are dependent on lattice helicity and elasticity. The density of SWNTs is estimated to be smaller (0.6g/cm ) than graphite due to the presence of hollow channels in the center of CNTs. As expected for nano-sized materials, the surface area of CNTs is very large, e.g. 10-20m /g for MWNTs and the value of SWNTs is expected to be an order of magnimde higher. Some detailed discussion of the mechanical, electronic, and chemical properties of CNTs can be found in the following sections. 

In the former, corona discharges occur in voids, causing hollow channels, lined with decomposed polymer, grow in the polymer. The field strength to cause corona discharge should be an inverse function of the void diameter, so breakdown should be avoidable if voids are smaller than 25 xm. 

HABA molecules were selectively and completely extracted with a selective solvent, such as methanol, resulting in nanoporous membranes with a hexagonal lattice (24 nm in the period) of hollow channels of 8 nm in the diameter crossing the membrane from the top to the bottom. The walls of the channels were again constituted from reactive P4VP chains. 

Sidorenko et al. succeeded in fabrication of well-ordered nanostructures in thin polymer films by supramolecular assembly of PS-Zi-P4VP and 2-(4-hydro-xybenzeneazo) benzoic acid (HABA), consisting of cylindrical nanodomains formed by P4VP-HABA associates in a matrix of PS (Sidorenko et al., 2003). As shown in Scheme 12.7, extraction of HABA with a selective solvent results in nanochannel membranes with a hexagonal lattice of hollow channels in the diameter crossing the membrane from top to bottom. 

In most cases, plastic products can take advantage of a basic beam structure in their design. Hollow-channel, T, T-shapes, and cantilever... 

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