Perspex plastic

Because hybridization is carried out at a high temperature for long periods, it is important to prevent drying out of sections Well-sealed Perspex plastic boxes or empty plastic, Boehringer enzyme boxes, stuffed with tissues soaked in 3X SSC, and with a platform (i.e., made from cut plastic pipets taped to the bottom of the box) for placing slides horizontally, can be used as homemade hybridization chambers in a water bath. 

During this period, the ICI laboratories were also making their other great contribution to the range of plastics materials—the product which they marketed as Perspex, poly(methyl methacrylate). As a result of work by two of their chemists, R. Hill and J. W. C. Crawford, it was found that a rigid transparent thermoplastics material could be produced at a commercially feasible cost. The material became invaluable during World War II for aircraft glazing and to a lesser extent in the manufacture of dentures. Today poly(methyl methacrylate) is... 

In radiation sterilization, a plastic (olien perspex) dosimeter which gradually darkens in proportion to the radiation absorbed gives an accurate measure of the radiation dose and is considered to be the best technique currently available for following the radiosterilization process. 

Acrylic Sheet (e.g. Perspex) Acrylonitrile Butadiene Styrene Resins (1) Nylon 66 Fibre (m) Nylon 66 Plastics (m) PCTFE PTFE (n) PVDF (y) Rigid Unplasticised PVC Plasticised PVC ... 

Theses polymers are made from acrylic acid, its homologues and their derivatives. Glass like resins were made from esters of aerylic acid in 1877 by Fitting and Peter by Kahlbaum. In 1928, Rohm and Hass, a German Company started commercial development of methacrylic esters. Limited production started in 1933. The rapidly expanding air-force used this plastic in place of glass in the aeroplanes. Most of the early production of "Plexiglass was used up by air-force planes. In 1936, ICI marketed methyl methacrylate sheets as "Perspex". 

Figure 4.20.A shows a more recent cell reported by Cobben et al. It consists of three Perspex blocks, of which two (A) are identical and the third (B) different. Part A is a Perspex block (1) furnished with two pairs of resilient hooks (3) for electrical contact. With the aid of a spring, the hooks press at the surface of the sensor contact pads (4), the back side of which rests on the Perspex siuface, so the sensor gate is positioned in the centre of the block, which is marked by an engraved cross as in the above-described wall-jet cell. Part B is a prismatic Perspex block (2) (85 x 24 x 10 mm ) into which a Z-shaped flow channel of 0.5 mm diameter is drilled. Each of the wedges of the Z reaches the outside of the block. The Z-shaped flow-cell thus built has a zero dead volume. As a result, the solution volume held between the two CHEMFETs is very small (3 pL). The cell is sealed by gently pushing block A to B with a lever. The inherent plasticity of the PVC membrane ensures water-tight closure of the cell. The closeness between the two electrodes enables differential measurements with no interference from the liquid junction potential. The differential signal provided by a potassium-selective and a sodium-selective CHEMFET exhibits a Nemstian behaviour and is selective towards potassium in the presence of a (fixed) excess concentration of sodium. The combined use of a highly lead-selective CHEMFET and a potassium-selective CHEMFET in this type of cell also provides excellent results.

For reasons of ease of manufacture, the majority of solid electrodes have a circular or rectangular form. External links are through a conducting epoxy resin either to a wire or to a solid rod of a metal such as brass, and the whole assembly is introduced by mechanical pressure into an insulating plastic sheath (Kel-F, Teflon, Delrin, perspex, etc.) or covered with epoxy resin. It is very important to ensure that there are no crevices between electrode and sheath where solution can enter and cause corrosion. Examples of electrodes constructed by this process will be shown in Chapter 8. 

The first ester, methyl methacrylate is a bulk chemical. It is the monomer whose polymerization (Chapter 52) gives Perspex, the rigid transparent plastic used In windows and roofs. The second ester is an important local anaesthetic used for... 

Various means of particle identification are possible with optical microscopy. These include dispersion staining for identification of asbestos particles [44] and the use of various mounting media [45], Proctor et. al. [46,47] dispersed particles in a solidifying medium of Perspex monomer and hardener. This was poured into a plastic mold that was slowly rotated to ensure good mixing. Microscope analyses were carried out on thick sections a lower size limit of 5 p,m was due to contamination. 

The surfaces of plastic materials, such as polyethylene, polypropylene or perspex, do not exhibit ion exchange, but adsorption may be pronounced, in partieular adsorption of organic compounds including organic complexes of radionuclides. 

Fig. 7.9. Flat-gel horizontal electrophoresis apparatus. Design of Vasu (1969), and reproduced here with details supplied by him. The apparatus is made of Perspex and the base plate (1) is 18.6x13.0x0.5 cm. The vertical pieces (2, 3, 4, 5) are all 3 X 1 X 0.2 mm, and the sides are defined by slats, 12 and 13, respectively 10.8 x 0.5 x 0.3 cm and 11.2 x 0.5 x 0.3 cm, and 14 and 16, which are 20 x 1 x 0.2 cm. The glass upper plate, 15, is 16 x 11 x 0.2 cm. This is placed on top of the base plate, resting on the slats (except the side piece 16) mounted as shown, 14 supported by 4 and 5, which are sealed to the plate. Likewise at the ends, are slats 12 and 13, the former supported by 2 and 3. The slot formers stick to the lower plate, and measure 1.2 X 0.2 X 0.2 cm. The acrylamide solution is poured down an inclined glass plate into the gap, and slat 16 is put in place. After polymerisation, the side slats are eased out with a razor blade and the device is inverted. The end pieces are likewise removed, and sheets of Whatman 6 MM paper are used to make contact with the reservoir, one layer above, another below the gel. After loading, and during the run, the gel is covered with a thin plastic sheet.

Fig. 7.15. Electrophoretic destaining apparatus (Richards and Gratzer 1968) cross sectional diagram of electrolytic destainer. Three gels are shown in the gel compartment (b) composed of a perspex (Incite) frame bounded by two sheets of Vyon porous plastic (d). This compartment rests in a holder made of two further perspex frames (a) joined along their bottom and sides. The gel compartment and the porous plastic are held in the holder by a fourth removable perspex frame (c). The holder fits tightly into a perspex tank (e) and thus separates the two buffer compartments (g), which are normally filled with 10% acetic acid. The potential is applied through two j in carbon rods (f) which are mounted in the tank through rubber grommets.

Figure 4.1 Diffraction patterns of usual sample holders (0.5° div. slit). For thin samples, or with a too wide divergence slit, these patterns may be superimposed on the sample pattern. For a plastie framed background free Si single crystal holder a plastic hump appears in the lower angle area (for 1° div. slit this starts already at 18 ), The sharp reflections in 2 originate from the inorganic filler (feldspar ). Normal white Perspex resembles the given plastic curve (4). A blue Perspex of unknown origin was found to be almost free of background (3).

Radiation is a major hazard and its stochastic effects should not be underestimated (Ballance et al., 1984). For instance, -particles emitted by have a maximum range of 6 m in air, but less in glass (0.38 cm). Perspex (Plexiglas, 0.64 cm) or water (0.84 cm). The maximum permissible occupational skin dose equivalent in the United States is 30000 mRem/year (7500 mRem/3 months) but six times lower for the lens of the eye. The dose equivalent rate at the surface of a glass container with P (such as Combi-v-vial ) can be close to 500 mRem/hmCi whereas it may be over 170000 mRem/hmCi outside a plastic syringe with a P solution (Zoon, 1987). Without precautions, the maximum permissible dose can thus be received in a matter of minutes or even seconds. In contrast, S does not penetrate the walls of typical containers or the dead layer of skin cells. The main hazard of S is due to inhalation. 

FIGURE 6.7 Schematic representation of manual sample introduction using syringes with (left) or without (right) a needle. 1 — syringe piston 2 = sample inserted volume 3 = needle 4 = flexible plastic septum 5 = main analytical channel (top view) 6 — Perspex support. 

Methyl ester, methyl methacrylate, polymerizes easily, forming a clear plastic known as Lucia, Plexiglas, Perspex. Sol in methyl ethyl ketone, tetrahydrofuran, esters, aromatic and chlorinated hydrocarbons. LDm orally in rats 8.4... 

Polymethylacrylate (PMA) and polymethylmethacrylate (PMMA) were discovered, respectively, in 1880 and 1930. The resins have been used for the production of transparent plastic sheets, viz. Plexiglas or Perspex , used for the military aircraft cockpit canopies, gunner s turrets and the like [Riddle, 1954]. Acrylic elastomers (ACM or ANM) were developed by Rohm in 1901, and commercialized in 1948 as Hycar vulcanizable copolymers of ethyl acrylate, allyl maleated lactones, chloroethyl vinyl ether, butadiene, isoprene, acrylonitrile, etc. [Mast et al., 1944]. Since the 1950 s, a wide variety of acrylic compatibilizers and impact modifiers have been developed. 

The transparent antistatic coating for meter windows is an old requirement and this coating has been used for many years on both glass and plastic substrates. Figure 42 shows the spectral characteristic of such a film. The surface resistance of approximately 1015 ohms/square of Perspex, is reduced to less than 105 ohms/square by the antistatic film. This resistance is not exceeded through ageing processes. The... 

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