The mean contents of trace elements in anterior gray horn section of cervical spinal cords of six amyotrophic lateral sclerosis (ALS) cases were relatively determined against those of six control cases by α-particle excited X-ray fluorescence analysis. The anterior gray horn section of cervical spinal cord samples were excited by 1.6 Me V α-particle beam of 2 mm diameter accelerated with a Van de Graaff accelerator, and characteristic X-ray spectra were measured with a Si (Li) detector. From the peak areas on the X-ray spectra, the relative mean contents of the trace elements in cervical spinal cords of ALS and control cases were determined. As a result, the X-ray peaks of Al, Si, P, S, C1, K, Ca, Ti, V, Mn, Fe, Cu and Zn were detected. The contents of Al, Si, P, Ca, Ti, V, Mn and Fe in ALS cases were higher than those in control cases. The contents of S, Cl, K, Cu and Zn in ALS and in control cases were equal to each other within standard deviation. The precipitation mechanisms of Al, Si, P, Ca, Ti, V, Mn and Fe into cervical spinal cord of ALS cases are discussed on the basis of the previous studies.
Redox substoichiometry in neutron activation analysis has been applied to the determination of antimony content in metallic tin of chemical grade. The substoichiometric separation is based on the extraction of unreacted antimony (III) with an excess of N-benzoyl-N-phenylhydroxylamine (BPHA) after the substoichiometric oxidation of antimony (III) with potassium bromate. Interference for the quantitative substoichiometric oxidation of antimony (III), caused by any other materials reacting with bromate, such as arsenic (III), could be prevented by the addition of large amounts of antimony (III) carrier before substoichiometric oxidation. Only about one hour is required for the antimony analysis of metallic tin, excluding the irradiation period of sample. The antimony content of 1.22±0.14μg in metallic tin (10 mg) was determined without separation of the matrix element.
The lesion detectability with a scintillation camera as a function of count density was determined for the four spherical cold lesions with diameter 0.9-2.5 cm (in√2 step) within a uniform background activity. It can be seen from the curves that the lesion detectability in-creases with an increase in count density until 2 kcounts/cm2, however it does not appreciably improve for count densities above 2 kcounts/cm2. The curves also show that, for a giving count density, the lesion detectability decreases as the lesion size or object contrast decreases. From these curves minimum count density required for recognition of each cold lesion is de-duced. This value is applied to the evaluation of scintillation camera system.