Fundamental-oriented research activities

Time resolved spectroscopy has developed assignments of intermediate species in radiation chemistry as revealed in the other sections. However, because solid polymers are less transparent, the works obtained so far seem to be limited mainly to polymer solution systems or liquid model-compounds. The lifetime of intermediates depends on LET the fluorescence lifetime of n-dodecane is shorter for higher LET radiation [83], which was studied as liquid model compounds for polyethylene. The observation is attributed to scavenging upon encountering of intermediates. Light emission from excimers of solid polystyrene has constant lifetime irrespective to LET [84], whereas polystyrene 

Track radius, corresponding to chemical core in the previous section, is discussed from fluence-dependence of radical saturation [95], convergence of molecular weight distribution [88], and decay of optical density [96], under the assumption that inter-track overlapping would affect these phenomena. The track radius thus evaluated ranges from a few to several dozen nanometers, and increase with increasing LET. 

However, the general tendency seems that, in despite of large difference in stopping power, the yield is influenced less profoundly. Furthermore, the 

Stopping power can not be the universal parameter though it is still good one, that is, even at a fixed stopping power, the velocity of ions can severely affect the irradiation effects [41, 97]. The similar example was already found for liquid hydrocarbons as seen in the previous section [68], These findings have evoked the concept of radiation-quality effect, as a natural extension of LET effect. 

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While the trend of the research activity in the area of multiplicity and periodic activity in the 1960s has been focused on theoretical investigation, the recent development has indicated an increase of experimental information. However, the number of experimental papers in comparison with the theoretical studies is still low and the need for additional laboratory studies is obvious. We have tried in this report to focus only on experimental papers and on behavior of real systems. We hope that a qualitative description of multiplicity and oscillations phenomena presented here will catalyze the research oriented to more detailed investigation of fundamental laws governing transport phenomena in chemically reacting systems. 

U.S. chemistry leadership will diminish in core areas. The growth in applications-oriented research and molecularly oriented bio- and materials-related activities has been accompanied by a parallel decrease in funding for basic research in some fundamental core areas of physical chemistry and organic chemistry. Core research areas, which underlie advances in emerging areas of science, are likely to continue to struggle for research support. Japan and Europe maintain more balanced support between core and emerging areas of chemistry. In some core subareas, such as main group chemistry, nuclear and radiochemistry, and basic theory, the U.S. position has already noticeably diminished. 

Fundamental research in pyrotechnics is published in the US in Combustion and Flame by the Combustion Institute, and in the UK in Combustion Science and Technology and in Fuel . Germany has the new, journal, Propellants and Explosives (German Chemical Society), which is the successor to the discontinued Explosivstoffe . A necessary caveat is that these journals are strongly oriented toward combustion or propulsion so that only rarely do they yield pyrotechnic information. Likewise, the various publications of the learned societies contain much data on thermodynamics, spectroscopy, and instrumental analysis which are useful in the study of pyrotechnics. In the USSR the situation is somewhat better as Physics of Combustion and Explosion (Fizika Gorenia i Vzryva) of the Siberian Branch Academy of Sciences USSR is exclusively oriented toward subjects of interest, as several scientific institutes are primarily devoted to research in pyrotechnics. The same authors do publish also, however, in the journals of the Academy of Science USSR (of which there are several) as well as in the corresponding journals of the academies of the various republics, so that the impression is created of a high level of activity... 

The paper is not equation oriented since after the period of theoretical investigation, only a small percentage of experimental papers published is completely supported with theory and very often only a qualitative explanation is presented. Hence in this paper we shall review the experimental information published in the literature concerning multiplicity of steady states and periodic activity in the systems catalyst-gas, making an attempt to explain qualitatively these phenomena on the basis of the theory developed.1 The number of experimental observations surveyed here which are not supported by a theory will surely indicate that there are many roads open for fundamental research in this area. 

There is little question that one of the most active research areas in materials science is studying interfaces. In the past, emphasis in materials science has been placed on relating the bulk properties to the structure and composition of the solid. Today, efforts are in progress that relate surface reactivity and stability to the crystallographic orientation and composition, primarily at the S/G interface. Since a fundamental understanding of interfacial behavior and degradation mechanisms at an atomistic level is necessary if short-time test data are to be extrapolated to 30-year lifetimes, careful studies at the S/S, S/G, and S/L interfaces are required (4). 

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