Radiation effects affected

Radiation adversely affects limb regeneration of amphibians, alters DNA metabolism, and increases the frequency of chromosomal aberrations and liver lesions (Table 32.25). In some species of amphibians and reptiles, as in many mammals, mortality rates after acute exposure to radiation do not stabilize within 30 days — effectively invalidating the conventional LD50 (30-day postexposure) value. In the rough-skinned newt (Taricha granulosa), for example, the minimal LD50 dose at 200 days after irradiation was 2.5 Gy, compared with 350 Gy at 30 days (Willis and... 

Radiation, of course, affects specific chemical substances present in biological systems. It appears evident that when the enzymic and hormonal levels of two individuals differ markedly in pattern by inheritance, there will be corresponding differences (as there are in mice) to radiation effects. 

National Research Council, Comparative Dosimetry of Radon in Mines and Homes, Panel on Dosimetric Assumption Affecting the Applications of Radon Risk Estimates, Board on Radiation Effects Research, Commission on Life Sciences, National Academy Press, Washington, D.C., 1991. 

Gamma Radiation Effect on Explosives. Using Au-198 radiation the most affected were NG and PbNa, while TNT and Pb sryphnate were most stable. Binary expls such as Ballistite Comp B, primers such as M26 also were studied (Ref 1)... 

Materials and Methods. The isomeric compositions of the four polybutadienes used are listed in Table I. Samples were prepared for infrared measurement from solutions of the polymer without further purification. Most films were cast from carbon disulfide solutions on mercury or on glass plates, but a few films were cast from hexane solutions to determine whether or not the solvent affected the radiation-induced behavior. No difference was observed for films cast from the different solvents. The films were cured by exposure to x-rays in vacuum. (Doses were below the level producing detectable radiation effects.) They were then mounted on aluminum frames for infrared measurements. The thicknesses of the films were controlled for desirable absorbance ranges and varied from 0.61 X 10 s to 2 X 10 3 cm. After measuring the infrared spectrum with a Perkin-Elmer 221 infrared spectrophotometer, the mounted films were evacuated to 3 microns and sealed in glass or quartz tubes (quartz tubes only were used for reactor irradiations). 

White and yellow strains of sweet Spanish onions have recently been irradiated by the Brookhaven group (D5). An 8,000-r. treatment was found to be completely effective in sprout suppression although there was no indication that any of the radiation treatment affected rotting, which proceeded at a normal rate. 

Recently Freeman, Anderson and Campisi [11] examined the effects of X-rays on the chemical reactivity of ammonium perchlorate in the solid state. They found that pre-exposure of ammonium perchlorate to high energy radiation greatly affects the way it decomposes thermally. 

The climate effects of atmospheric aerosol particles are a matter of continuous interest in the research community. The aerosol-climate effects are divided into two groups The direct effect represents the ability of the particle population to absorb and scatter short-wave radiation - directly affecting the radiation balance. These direct effects depend primarily on the aerosol optical properties and particle number size distribution, as the particle size significantly affects the scattering efficiency of... 

Workers also are affected by a variety of radiations, specifically UV. This radiation consists of UVA, UVB, and UVC, which induces certain skin lesions (Table 16-2). To protect the skin from the injuries from UVA and UVB radiation effects, certain drugs are suggested such as aminobenzoic acid, aminobenzoates, cinnamates, salicylates, and camphors for UVB protection, and benzophenones or dibenzoylmethanes for UVA protection. 

Banford et al. studied the radiation effects on electrical properties of low-density polyethylene (LDPE) at 5 K with the use of a 60Co gamma source and a thermal nuclear reactor [86]. They reported that both the electrical conductivity and the dielectric breakdown strength of LDPE at 5 K were not significantly affected by radiation absorbed doses up to 10s Gy, but an erratic pulse activity under high applied fields was observed in the sample irradiated at 106 Gy. 

The radiation effect is very likely based on the oxidation of iodine by radiolytical products into the I+ form, but it is very difficult to analyze in detail the processes underlying the complex mechanism of the effect. Higher sensitivity of astatine towards oxidation indicates that strong alpha radiation of21 At could affect the labelling with this radionuclide even negatively (oxidation into higher oxidation states). 

C Give examples uf radiation effects that affect human comfort. 

At the chemical level, a solute molecule (DNA, RNA, and protein) in a biological system can be affected by radiation in two different ways. When an ionization track passes either directly through a molecule or close enough so that the created ions can drift to and interact chemically with the molecule before they recombine and neutralize in solution, the phenomenon is called a direct radiation effect. On the other hand, since the largest fraction of almost any biological system consists of water (e.g., 70-80% of a typical cell), the most frequent initial radiation interactions will be with water molecules. When this occurs, ion radicals and free radicals are created. 

This latter phenomenon is called an indirect radiation effect. If RH is an important molecule (e.g., DNA and RNA) then these interactions can affect cell functions. 

Sunlight and other sources of nonionizing electromagnetic radiation can affect foods. For example, it has been shown that sodium nitrite, sodium nitrate, sodium benzoate, potassium sorbate, and benzoic acid exhibit additive photogenotoxic effects on Escherichia coli, causing increased mutations upon exposure to sunlight. I76l Such effects potentially increase the toxic risks associated with food additives. 

Another special topic apart from the main line of interest is the use of radiation to affect some precursor of a catalyst during the process of catalyst preparation (Section V,B). This may involve the effect of radiation on the colloidal properties of a precipitate in a wet preparation, or the production of defects in a solid which is to be subsequently converted to a catalyst by calcination or by reduction. 

Labeled compounds experience self-radiolysis induced by the radioactive decay. The extent of such radiation effects depends on the half-life, the decay energy, the specific activity of the sample, and the G-value for decomposition. The presence of other substances can considerably affect the amoimt of damage. Aromatic compounds such as benzene (as a solvent) can serve as a protective medium to minimize radiation self-decomposition, whereas water or oxygen enhance it. 

Radiation doses of 10 Gy can induce decomposition effects of the order of 1 %. Samples whose specific activity exceed 40 GBq (1 Ci)/mol for or about 400 GBq (10 Ci) per mol for will receive a dose of this magnitude in a period of a year. Samples may be stored in benzene solution in vacuo or in deep freeze to minimize self-radiation effects and should be re-purified before use if the decomposition products are likely to affect the experiment. 

Radiation can affect the body in a number of ways, and the adverse health effects of exposure may not be apparent for many years. 

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