Linear energy transfer effects

Differences in the degradation behaviour of polymers in solution as a function of LET has indeed been observed by Henglein and co-workers. The results obtained for various polymers are summarized in Table 35 [442]. The more efficient radiation has been underlined in the cases where the effects of high and low LET are qualitatively the same. For the dilute solutions ( 1%), the more efficient radiation is Li—He in only one 

REACTIONS AT LOW AND HIGH POLYMER CONCENTRATIONS INDUCED BY 7-RAYS AND He-Li PARTICLES [442] 

Polyvinyl- chloride Dimethylformamide 1 triethyl-cyclohexanone 1 borate Microgel formation Microgel formation Intermol. crosslinking Intermol. crosslinking 

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Swiatla-Wojcik D, Buxton GV (1998) Modelling of linear energy transfer effects on track core processes in the radiolysis of water up to 300°C. J Chem Soc Faraday Trans 94 2135-2141 Sychev AY, Isak VG (1995) Iron compounds and the mechanisms of the homogeneous catalysis of the activation of O2 and H2O2 and of the oxidation of organic substrates. Russ Chem Rev 12 1105-1129... 

Modulation of the Killing of Mammalian Cells by Thiols. Important aspects of the effects of exogenous thiols on clonogenic cell survival following exposure to low linear energy transfer (LET) radiations include the following. 

Quality Factor (Q)—The linear-energy-transfer-dependent factor by which absorbed doses are multiplied to obtain (for radiation protection purposes) a quantity that expresses - on a common scale for all ionizing radiation - the approximate biological effectiveness of the absorbed dose. 

The range in tissues and linear energy transfer (LET) depend on the type of radiation emitted and its energy. The potent lethality of Auger and low-energy conversion electrons is demonstrated by intranuclear localization of the radioisotope due to their short ranges (about one cell nucleus in diameter). Alpha particles have ranges of several cell diameters (40-90 pm) and are effective in... 

Figure 31 The relative biological effectiveness (RBE) of lethality as a function of linear energy transfer (LET). (From Refs. 105 and 106.)...

The National Coimdl on Radiation Protection and Measurements (NCRP) has been concerned from its inception with assessment of the risks of low-level irradiation. In recent years, this concern has prompted increasingly detailed efforts to quantify the influence of dose, dose rate, and linear energy transfer (LET) on the biomedical effects of radiation, with particular reference to the carcinogenic risks of low-level exposure (NCRP, 1980) and the work-in-progress of NCRP Sdentific Committee 40 on LET and relative biological effectiveness. 

FIGURE 7. Dependence of relative biological effect (RBE) and of oxygen enhancement ratio (OER) on the linear energy transfer (LET) of radiation. Reprinted from Brown, Appl. Radiat. Isot., 37, 789 (1986) (Reference 84) by kind permission of Elsevier Science Ltd, The Boulevard, Langford Lane, Kidlington, OX5 1GB... 

The effect of Linear Energy Transfer (let) on the radiolysis of methyl iodide has been studied by Sturm and Schwarz The increase of the yields of ethane, methane, hydrogen, ethylene and acetylene with let supports the view of Gillis et that these products are formed by diffusion-controlled reactions of radicals... 

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