Ultraviolet sterilisers

Removal by passing through ultraviolet sterilisers (Summerfelt 2003) is commonly recommended but can deal with only small amounts of water and is thus reserved for small tank use. It is also debatable how effective this is against parasites but evidence suggests it can be useful for small protozoa provided the distance is within a few microns. Subasinghe (1980, personal communication) showed that theronts of I. multifiUis could be destroyed in this way but would be suitable for use only on a small scale such as for small ornamental fish tank use. A number of methods should be combined to improve the efficiency of removal of potential pathogens. 

Radiation sterilisation is used mainly for the sterilisation of heat sensitive materials and products. Many medicinal products and some packaging materials are radiation-sensitive, so this method is permissible only when the absence of deleterious effects on the product has been confirmed experimentally. Ultraviolet irradiation is not normally an acceptable method of sterilisation. 

Sterilisation can be affected by moist or dry heat, by ethylene oxide (or other suitable gaseous sterilising agent), by filtration with subsequent aseptic filling into sterile final containers, or by irradiation with ionising radiations (but not with ultraviolet radiation). Each method has its particular applications and limitations. Where possible and practicable, heat sterilisation is the method of choice. 

In order to conduct this test, erythrocytes are separated from plasma and the buffy coat and washed three times with five volumes of phosphate buffer saline (PBS, pH = 7.4). The RBCs are collected in a centrifuge under specified conditions (3000 g for 10 min at 25°C). The compacted cells are then suspended in four volumes of PBS for the experiment. The surfaces of all the experimental samples are sterilised for 30 min in ultraviolet light under a sterile laminar air hood. 

High-energy radiation such as ultraviolet (UV) radiation, X-rays, y rays and electron beams can initiate polymerisation. Radicals formed into polymeric materials during sterilisation by such radiation have a long life, especially in the bulk of the material, and can initiate new polymerisation. Such an initiation process has been used widely to modify polymeric surfaces by grafting another polymer. 

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