Oxidation with light

Firefly luciferase catalyzes a bioluminescent reaction in which the substrate luciferin is oxidized, with light as a by-product. The light from this reaction can be measured quantitatively with a luminometer or a scintillation counter. The bioluminescence of luciferase has been measured in Drosophila tissue culture extracts (see Van Ohlen et al. 1997 Sawado et al. 1998) and in whole flies and isolated body parts (Brandes et al. 1996 Emery et al. 1997 Stanewsky et al. 1997,1998 Plautz et al. 1997a,b). Luciferase has been a very valuable reporter for measuring circadian rhythms in living flies and isolated body parts. 

Fig. 37. Resist images obtained with a cross-linking monocomponent TSI resist (PHOST polymer), cross-linked by photo-oxidation using light at 193-nm wavelength. After exposure, the film was treated with a vapor of dimethyl silyl dimethyl amine and then plasma developed using O2—RIE (122).

Sta.nnous2-Ethylhexa.noa.te, Stannous 2-ethyIhexanoate, Sn(CgH 302)2 (sometimes referred to as stannous octanoate, mol wt 405.1, sp gr 1.26), is a clear, very light yellow, and somewhat viscous Hquid that is soluble in most organic solvents and in siHcone oils (166). It is prepared by the reaction of stannous chloride or oxide with 2-ethylhexanoic acid. 

Although there are minor differences in the HCl—vinyl chloride recovery section from one vinyl chloride producer to another, in general, the quench column effluent is distilled to remove first HCl and then vinyl chloride (see Eig. 2). The vinyl chloride is usually further treated to produce specification product, recovered HCl is sent to the oxychlorination process, and unconverted EDC is purified for removal of light and heavy ends before it is recycled to the cracking furnace. The light and heavy ends are either further processed, disposed of by incineration or other methods, or completely recycled by catalytic oxidation with heat recovery followed by chlorine recovery as EDC (76). 

Vitamin D deficiency in animals may be caused by the fact that the vitamin is not available to the hvestock. Modem animal husbandry subjects animals to total confinement with htde or no exposure to sunlight. This mandates that they be given vitamin D-fortified diets. The vitamin is sensitive to oxidation, heat, light, and minerals, and significant losses may occur in the fortified feed unless the product is adequately protected. Mycotoxins in feeds also interfere with utilization of vitamin D in feeds (207—209). 

The most important reactions of trichloroethylene are atmospheric oxidation and degradation by aluminum chloride. Atmospheric oxidation is cataly2ed by free radicals and accelerated with heat and with light, especially ultraviolet. The addition of oxygen leads to intermediates (1) and (2). 

Hydrogen peroxide can also be activated by ultraviolet radiation or o2one and ultraviolet radiation (178,188,189). One of the most active fields in waste treatment is ultraviolet-cataly2ed oxidation with hydrogen peroxide (190—194). The uv light activates the hydrogen peroxide converting it to hydroxyl radicals (195). 

A combination of ozone oxidation with simultaneous exposure to ultraviolet light seems to produce a self-renewing chain reaction that can significantly reduce the dose of ozone needed to accomphsh oxidation. 

Cinchoninone, CigHaaONj, produced by the oxidation of either cinchonine or cinchonidine by chromic acid in presence of sulphuric acid forms pale yellow prisms, m.p. 126-7°, [a]j) -(-71° to -(-76°, is sparingly soluble in light petroleum, easily in ether or chloroform and insoluble in water. The hydrochloride forms minute colourless needles, m.p. 245-7°, [a]r) -(-175-9°. By further oxidation with chromic acid, cinchoninone yields cinchoninic acid and meroquinenine (meroquinene). 

To identify the specific aldehyde that is actually involved in the light-emitting reaction of living luminous bacteria, Shimomura et al. (1974a) extracted and purified the aldehyde from 40 g each of the bacterial cells of P. phosphoreum, Achromobacter (Vibrio or Photobacterium) fischeri, and an aldehydeless mutant of A. fischeri. The aldehyde fractions were purified, and then oxidized with Tollens reagent (silver oxide dissolved in ammonia) to convert the CHO group into the COOH group. Then the acids obtained were analyzed by mass spectrometry. The results indicated that P. phosphoreum had contained a mixture of aldehydes dodecanal (5%), tetradecanal (63%) and hexadecanal (30%), as shown in Table 2.2. Thus, tetradecanal was clearly predominant in... 

According to the information available, it would be reasonable to consider that P. stipticus emits light when its natural luciferin is oxidized with molecular oxygen in the presence of OJ and a suitable surfactant (Shimomura et al., 1993b). Also, it seems almost certain that the natural luciferin is formed from PS-A, PS-B and a simple primary amine by the addition and condensation reactions. 

Interesting results have also been obtained with light-induced oscillations of silicon in contact with ammonium fluoride solutions. The quantum efficiency was found to oscillate complementarity with the PMC signal. The calculated surface recombination rate also oscillated comple-mentarily with the charge transfer rate.27,28 The explanation was a periodically oscillating silicon oxide surface layer. Because of a periodically changing space charge layer, the situation turned out to be nevertheless relatively complicated. 

A thin film of tin oxide with a rough texture, produced by MOCVD from tetramethyl tin, (CH3)4Sn, deposited on an amorphous silicon cell provides a light-trapping surface, which enhances the efficiency of the device. 

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