Ultraviolet sterilization

Water is the most common raw material used, and it is recommended that the manufacturer fully comply with the standards of at least purified water for inclusion in the formulation, though there is no requirement. Efforts should be made to provide as much microbial-free water as possible this can be readily achieved by installing a loop system in which the incoming water is first subjected to ultraviolet sterilizer, carbon filter, demineralizer, and a... 

G. O. Schenck, Ultraviolet Sterilization , in Handbook of Water Purification, W. Lorch, Ed., McGraw Hill, London, 1981, Chapter 10, p. 363. 

Molecules and Subphase We confine our discussion here to the most popular supporting liquid for monolayer studies, that is, water. The quahty of water is of prime importance to the LB studies. Many researchers choose an ultrapure water system, which includes mixed anion and cation exchange resins, a reverse osmosis unit, ultraviolet sterilizer, and photooxidation unit, supplying water of high specific resistance (1.8 x 10 2m) and total organic contamination (TOC) in the ppb (parts per 10 ) level. 

In the lamp industry, the three gases serve as fill gas in specialty lamps, neon glow lamps, 100-watt fluorescent lamps, ultraviolet sterilizing lamps, and very high-output lamps. The three gases have additional applications in the atomic energy field as fill gas for ionization chambers, bubble chambers, gaseous scintillation counters, and other detection and measurement devices. 

Treatment with Cl 2 or adsorption on high-surface-area carbons, osmosis, ultraviolet sterilization... 

As mentioned in Chapter 3, DI water has now replaced distilled water for most laboratory purposes. PVC pipe, which is both inexpensive and easy to install, is normally employed to carry the water to points of usage. It is very important that the lines do not have dead legs where water is allowed to stand, since this could encourage bacterial growth. In cases where sterile water is needed, special steps must be taken. The water may be boiled, which also drives out dissolved gases, or ultraviolet radiation may be employed, a common method in the cosmetics industry. Membrane filters will also effectively remove bacteria. Laboratories needing sterile water often use two bacteria removal systems of... 

The British Pharmacopoeia (1993) recognizes five methods for the sterilization of pharmaceutical products. These are (i) dry heat (ii) heating in an autoclave (steam sterilization) (iii) filtration (iv) ethylene oxide gas and (v) gamma or electron radiation. In addition, other approaches involving steam and formaldehyde and ultraviolet (UV) light have evolved for use in certain situations. For each method, the possible permutations of exposure conditions are numerous, but experience and product stability... 

Sterilization. In some processes, such as food and beverage and pharmaceutical processes, water might need to be sterilized before it is reused or recycled. Chemical oxidation (e.g. ozonation) can be used. Ultraviolet light is an alternative for lightly contaminated water. Alternatively, a combination of chemical oxidation and UV light can be... 

UV-C technology is widely used as an alternative to chemical sterilization and microorganism reduction in food products (Lamikanra 2002 Fan and others 2008). Ultraviolet light also induces biological stress in plants and defense mechanisms in plant tissues with the consequent production of phytochemical compounds (Lee and Kader 2000). Phytoalexin accumulation could be accompanied by other inducible defenses such as cell-wall modifications, defense enzymes, and antioxidant activity, which have been reported with health benefits (Gonzalez-Aguilar and others 2007). It is well documented that UV-C irradiation has an effect in secondary metabolism. 

In Chapter 5.4, optical ultraviolet radiation sensors are described, including UV-enhanced silicon-based pn diodes, detectors made from other wide band gap materials in crystalline or polycrystalline form, the latter being a new, less costly alternative. Other domestic applications are personal UV exposure dosimetry, surveillance of sun beds, flame scanning in gas and oil burners, fire alarm monitors and water sterilization equipment surveillance. 

Sterilization can be accomplished by several means, including heat, chemicals, radiation (ultraviolet (UV) or y-ray), and microfiltration. Heat is widely used for the sterilization of media and fermentation equipment, while microfiltration, using polymeric microporous membranes, can be performed to sterilize the air and media that might contain heat-sensitive components. Among the various heating methods, moist heat (i.e., steam) is highly effective and very economical for performing the sterilization of fermentation set-ups. 

Ultraviolet (uv) light has also been used to sterilize the water in aquaculture systems. The effectiveness of uv decreases with the thickness of the water column being treated, so the water is usually flowed past uv lights as a thin film (alternatively, the water may flow through a tube a few cm in diameter that is surrounded by uv lights). Uv systems require more routine maintenance than ozone systems. Uv bulbs lose their power with time and need... 

Many cellular materials absorb ultraviolet light, leading to DNA damage and consequently to cell death. Wavelengths around 265 nm have the highest bactericidal efficiency. However, ultraviolet rays have very little ability to penetrate matter. Therefore, their use is limited to the reduction of microbial population in a room where sterility needs to be maintained, such as hospital operating rooms or clean chambers in a laboratory. X-rays are lethal to microorganisms and have penetration ability. However, they are impractical as sterilization tools due to their expense and safety concerns. 

Demethylation refers to the removal of methyls from organoarsenicals, which may ultimately transform the organoarsenicals into inorganic arsenic. Although exposure to ultraviolet radiation may demethylate arsenic (Cullen and Reimer, 1989), 741, the role of microorganisms in demethylation is especially important. Under sterile conditions, MMA(V) and DMA(V) are very stable in water (Cullen and Reimer, 1989), 749. However, bacteria can demethylate them and other methylarsenic species into inorganic arsenic (Frankenberger and Arshad, 2002), 364 (Cullen and Reimer, 1989), 749 (Santosa et al., 1996), 703. 

Ultraviolet radiation Disinfection Considered a surface sterilizer only... 

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