Quench capability

The observation that lutein in the retina is converted to (meso)-zeaxanthin appears to be physiologically plausible due to the presence of, in comparison to lutein, one additional conjugated double bond, it has a stronger singlet oxygen quenching capability (Cantrell et al. 2003). Furthermore, it has been reported that (meso)-zeaxanthin provides a somewhat better protection against the oxidation... 

Ferrocene is marketed as one of the 24 compounds in the Photosensitizer and Quencher Kit wherein its efficient quenching capability is also noted.8... 

Oxidation of the styrene moiety and changes in the nitrogen environment in benzotriazole took place in 94. Available data confirm that the surface photooxidation of polymers containing aromatic moieties can differ from that of the bulk material [86]. This is due to the higher partial pressure of oxygen and incident photon flux in the surface area. Transmission IR data indicate that the quenching capabilities of benzotriazole moieties in the copolymer 94 are not active in inhibiting surface oxidation. 

In ischemia, the endogenous free radical quenching capability of the neurons diminishes further adding to cell stress. Consequently, free radical scavengers such as extract of Ginkgo biloba (Szabo et al., 1991), a-lipoic acid (Block and Schwarz 1997), vitamin E (Celebi et al., 2002), thioredoxin (Shibuki et al., 2000), an ascorbic acid derivative (Kuriyama et al., 2001), mannitol (Gupta and Marmor, 1993), and the iron chelator desferrioxamine (Ophir et al., 1994) have all been shown to be neuroprotective in ischemia-reperfusion injury. 

The machine should have the screw diameter D > 30 mm, with length to diameter ratio L/D > 40. The extmder must provide an easy access to the reactive medium as well as the quenching capability with either screw or barrel removal. It must be fully instrumented with temperature and pressure sensors all along the barrel. It should offer the possibility of working under dry inert atmosphere, and have the capability of closed-loop control operation with an appropriate set of sensors. The machine should be equipped with a minimum of three feeders for solid and two for liquid ingredients. At least one vacuum system with cold trap is necessary. 

A fluorescence-based method was successfully tested for iodine determination in iodine-supplemented food, such as table salt and milk powder. It is based on the fluorescent quenching capability of iodine/triodide using a highly fluorescent compound consisting of a synthetic metal ion receptor coupled with a signaling element. The detection limit for triodide down to a concentration of 10 mol was reported (Zhao et al., 2003). 

An overview of stabilizer mechanisms and t5q>es of chemicals used for each mechanism is provided in Table 3. Further descriptions of these mechanisms follow. The three major classes of UV absorbers are 2-hydroxybenzophenones, 2-hydroxyphenylbenzotriazoles, and the newer 2-hydroxyphenyl-s-triazines. The nickel phenolates not only have excited state quenching capability, but also provide radical scavenging and hydroperoxide decomposing activity. The radical scavengers include hindered benzoates and hindered amines. The hindered amines have the added capability to decompose hydroperoxides. Another class of... 

Water has excellent quenching capabilities, cooling effectiveness, and, for some materials, vapor dispersion characteristics. Its high latent heat means that it absorbs a lot of heat when it is converted into steam by the fire. Moreover, the steam generated as fire vaporizes water can displace or exclude air, extinguishing a fire by smothering. 

Several conditions must be fulfilled in the chemiluminescence method. Experiments should be carried out in hydrocarbon, whose oxidation affords secondary (or primary) peroxyl radicals. The method was well approbated for ethylbenzene. It is important that all radicals of the initiator would react with hydrocarbon, finally exchanging to secondary peroxyl radicals. The initiator must no quench chemiluminescence. Since oxygen possesses a quenching capability, experiments must be carried out at such partial pressures of O2, which provide the fast transformation of R-into R02 , but the quenching effect of O2 is minimrrm. A photosensitizer is intro-... 

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