Radiation mechanisms

Goldman RH, Baker EL, Hannan M, et al. 1987. Lead poisoning in automobile radiator mechanics. N Engl J Med 317 214-218. 

Frederick, J. E., Trends in Atmospheric Ozone and Ultraviolet Radiation Mechanisms and Observations for the Northern Hemisphere, Photochem. Photobiol., 51, 757-763 (1990). 

Further insight into radiation mechanisms can be obtained by comparing different types of radiation, in particular alpha radiation, gamma (or fast electron) radiation, and ultraviolet light. Their effects are also important in such varied fields as space materials and radiological protection. 

So far I have confined my remarks to some aspects of radiation mechanisms in polymers. However, the use of radiation as a scientific tool has grown and is yielding valuable information in various fields, including polymer structure and radiation physics of polymers, and the results of this work are impinging on the vastly complex problems of radiobiology. It therefore seems appropriate to give a few selected samples of these techniques. 

It strongly supports that the energy source of X-rays both from an isolated pulsar and its nebula come from the rotating energy loss of the pulsar, and the energy transformation may be simply and directly. Eq.(l) offers a good empirical relation to further investigate their X-ray radiation mechanism. 

Diamond electrode — Electrode made from - boron-doped diamond or similar doped diamond materials. Diamond, natural or synthetic, exhibits some exceptional material properties such as low thermal expansion, optical transparency for visible, IR, and microwave radiation, mechanical strength, and shock resistance [i]. 

Here Sgain represents the rate (per unit mass) of energy gain from buoyancy forces and radiation mechanisms eioss represents the losses due to heat conduction and molecular viscosity and finally E,ransfcr is the energy trans-... 

The first attempt to resolve this problem was the radiation hypothesis of Perrin [1], in which the molecule is assumed to be energized by absorbing thermal radiation (in the infra-red) emitted by the walls of the vessel. However it was rapidly realized that the intensity of thermal radiation was quite insufficient to explain the observed rates of reaction [2], although interestingly, under conditions of extremely low collision frequency in interstellar space, Perrin s radiation mechanism is now believed to be significant [3]. 

In the case of solid crystalline oxides, thermal conductivity decreases with increasing temperature but begins to rise above 1500— 1600 °C because transmission of heat by radiation (photons) begins to take a significant part besides the conduction of heat (phonon mechanism). In completely transparent materials (the coefficient of absorption a = O), no interaction with the radiation occurs in an opaque body (a = oo) the heat is transferred by conduction alone. With translucent materials, each element of the substance absorbs some of the incident radiation, and emits simultaneously,This internal radiation mechanism of heat transmission is characteristic for glasses. At high temperatures, a considerable proportion of heat is therefore transmitted by radiation the so-called apparent thermal conductivity is a sum of true conductivity with radiation conductivity ... 

This is the area within the porous preform where the complex heat and mass exchanges occur. In this multiphase system the heat is transferred outwards through convective and radiation mechanisms. The precursor gases are supplied from the outside towards the reactive zone while the exhaust gases are transferred in the reverse direction after the chemical reactions. 

I have been asked to give an overview of the effects of hostile environment on plastics. Emphasizing not the degradation or destruction of the bulk polymeric material and its properties, but rather what is happening to individual macromolecules in hostile environments, and also to larger assemblies of them. The hostile environments to be discussed are heat, radiation, mechanical stresses and the presence of oxygen in combination with heat and radiation. 

This product of concentration into radiation density gives a more complex quantity, but, at the same time, probably a more accurate measure of the concept of active mass than is expressed in the classic concept of concentration alone This new measure of active mass is of significance not only for stoicheiometric reactions, but also for catalytic reactions, in which the catalyst may act in a stoicheiometric manner (expressible, in so fai as material change is concerned, by the ordinary stoicheiometric equations), and also for catalytic effects such as the influence of the solvent (or additions to the solvent) which cannot be expressed stoicheiometncally, since the effect has its origin in a physical (radiational) mechanism... 

Presentations by D. Meisel, G. Hug and J. LaVeme, underscored the relationship between fundamental research in radiation mechanisms and the emerging uses in applied technology.. Investigations into the concerns over hydrogen gas evolution and other by-products involved in nuclear waste storage were found to shed light on mechanisms found in commercially viable uses of radiation processing. 

The main objective of the rotary kiln section is to transfer the heat flux from the diffusion flames to the material to allow the clinkering reaction and noduliza-tion in the burning zone. As previously described the heat is transferred by conduction, convection, and radiation mechanisms to the material. 

It was found that the major mechanism in radiolysis of diaminobutyric acid in oxygenated solution is oxidative deamination on < - or y-position. This is clear from a comparison of the decrease in the content of diaminobutyric acid (G/-M/2.65), with the yield of ammonia (G 2.1) and with the yields of deaminated products (S G 2.0). Aside from carbonyl substances and ketoamino acids, /2-alanine and aspartic acid have been found among the products of oxidative deamination. In oxygen-free atmosphere, two of the main radiation mechanisms are reductive deamination (G/-M/1.4 and G NH3 1.2) and recombination reactions leading to products of higher molecular weight. 

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