This paper reports work done to compare the tensile creep, long-time tensile strength, and dynamic flexural fatigue-strength properties of some commercial melamine and phenolic-plastic materials. Tensile-creep data for woodflour-filled phenolic and cellulose-filled melamine indicate that these plastics exhibit similar characteristics, that is, the rate of elongation at 500 hr is essentially the same for the two materials. Likewise, the total elongation at 1000 hr is of the same order of magnitude for each of the materials. Similarly, asbestos-filled phenolic and asbestos-filled melamine show comparable tensile-creep properties. The long-time tensile strength of the cellulose-filled melamine is superior to that of the woodflour-filled phenolic material. The melamine has a long-time tensile strength of about 67 per cent of the short-time value (A.S.T.M. D638-41T), as compared with a value for the phenolic of approximately 36 per cent. Results of the repeated flexural-stress tests indicate that the woodflour-filled phenolic plastic is slightly superior to the cellulose-filled melamine, the endurance limit for the phenolic being approximately 4000 psi, or 34 per cent of the short-time static flexural strength, and for the melamine 3000 psi or 31 per cent of the short-time static flexural strength. Further tests of this nature would be desirable for the purpose of studying the effect of other fillers and formulations.
Although most of the radioactive fallout reaching the earth stays in the leaf layer and the top inch of soil, some is carried further into the soil and can be detected to a depth of several inches. This report describes a gammaray spectrometric study of fallout activity as a function of depth of soil. Total gamma activity deposited from recent tests was found to be over 1.5 curies per square mile at a site in eastern Indiana during July, 1962.
An important part of man's radioactive environment is the natural radioactivity of soils. This radioactivity varies with soil type and withdepth in the soil profile. The relation between gross gamma activity and soil depth for a particular soil (Miami silt loam) is presented, together with a discussion of the contribution of K(40) and the uranium and thorium series and of the effects of fallout from bomb tests in increasing the radioactivity of a thin layer of surface soil.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.