Enclosing plastics

Several innovative membrane-based bioreactor designs have recently been proposed, including that by Sussman et al. [10], which involves the cultivation of hepatoma cells on the exterior surfaces of semipermeable capillary hollow fiber membranes which are bundled together with an enclosing plastic shell (Fig. 2). Required nutrient medium is circulated within the capillaries. After the hepa-tocytes have attached and formed a mass of liver tissue, the capillary membranes are perfused with the media. 

To help find out exactly what goes on in these environmental carbon cycles a large totally enclosed plastic dome was constructed in Arizona in the early part of the 1990s, and the dome was filled with what was considered to be all the essentials for sustaining life air, water, food via plant material, soils, insects, small animals, rabbits (see Figure 6.1.1). 

A fume hood is constructed in the manner shown in figure 6. Strike drew the frame as being made of lumber but it can be made of rebar or, preferably, from PVC pipes and joints so that it can be assembled and disassembled with ease. The frame is enclosed with plastic drop cloths or any semiclear plastic sheeting. The front face of the hood is halfway covered with plastic while the bottom half is exposed to allow one to move objects in or out and to manipulate things. On top of the chamber is attached some clothes dryer duct or some such crap which is led to a leaf blower or blower motor. The exhaust from the blower is led away to the outside. 

Use enclosed conveyors and sieves for coal and coke handling. Use sprinklers and plastic emulsions to suppress dust formation. Provide windbreaks where feasible. Store materials in bunkers or warehouses. Reduce drop distances. 

Underground transmission lines are preferred in places where rights-of-way are severely limited because they can be placed much closer together than overhead lines. They are also favored for aesthetic reasons. They may be directly buried in the soil, buried in protective steel or plastic pipes, or placed in subterranean tunnels. The conductors are usually contained within plastic insulation encased in a thin metallic sheath. The conductors enclosed in steel pipes may be immersed in oil, which may be circulated for cooling purposes. For all types of underground lines, the capacitance is higher than for overhead lines, and the power transfer capability is usually limited by the resistive losses instead of the inductance. Wliile not exposed to environmental... 

Little comprehensive work has been carried out on contact corrosion, but some results on a range of polymers have been reported by Czech workers". In general, plastics that give rise to vapour corrosion (Table 18.18) will also cause contact corrosion. Some qualification is needed to this statement, however, as much depends on the type of contact and the other ingredients in the polymer, e.g. a paint may give good protection to the metal to which it is applied, but the vapour may cause corrosion of adjacent metal items within an enclosed space. 

To quiet a noise-generating mechanism, the first impulse is often to enclose it. Sometimes an enclosure is in fact the best solution, but not always. If it can be determined what is causing the noise, appropriate action can be taken to be more specific and provide a cost-effective fix. In some cases the problem is caused by a component such as a stepper motor or gear set that does not produce objectionable noise by itself. The trouble typically develops because a small noise is transmitted to a metal frame or cabinet that then serves to amplify the sound using a plastic cabinet can isolate the noise problem. 

Resin transfer molding With vacuum assisted RTM, this process can be called infusion molding. RTM usually uses liquid TS plastics that is transferred or injected into an enclosed mold usually at low pressures of about 60 psi (410 kPa) in which reinforcement... 

Also called conformal coating. It encloses a product in a closed envelope of plastic by immersing the product (solenoids, ornament, sensors, motor components, integrated circuits, and other articles.) in an unheated or... 

Permeation Tubes A volatile liquid, when enclosed in an inert plastic tube, may escape by dissolving in and permeating through the walls of the tube at a constant and reproducible rate. The permeation rate depends on the properties of the tube material, its dimensions and on temperature. 

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