For elements of Z=1 to 92 and energy ranging from 10 keV to 10 Me V, empirical equations of photon interaction (photoelectric effect, Compton effect, coherent scattering and pair production) cross section were formed. The calculated values agreed to the reference values except for those in some extreme cases, where discrepancies are practically insignificant. Mass attenuation coefficients for various materials of known element composition can be easily calculated with the empirical equations.
In general, the distillation parameters, such as the number of theoretical plate (NTP) and the height equivalent to a theoretical plate (HETP), can be obtained from the operation at the steady state. However, it is time-consuming to achieve the steady state especially in the case of isotope separation. In this paper, with the purpose of simultaneous separation of isotopes of nitrogen and oxygen by NO distillation, we tried to determine the distillation parameters by an analytical method through the transient-state operation. It was confirmed that the results from the analysis were in good agreement with those observed for the operation at the steady state. Enrichment of the isotopes was carried out using a distillation column with a height of 1 m and inside diameter of 12 mm. The dependence of HETP on liquid flow rate was measured by the proposed method. The obtaind HETP values were from 2 to 4 cm. The operation time of about 5 h was found to be long enough to determine the distillation parameters.
A new non-destructive analytical method for226Ra has been proposed which corrects the activity of226Ra determined by γ-ray spectrometry, using that of238U determined by the epithermal neutron activation analysis. The activity of226Ra obtained by this method was compared with the activity of214Bi measured more than 30 days after sealing the sample, by the usual non-destructive method, which took such a long time to analyze. The value of226Ra derived from the214Bi data fluctuated and was underestimated because of loss of222Rn probably due to imperfect sealing. The present method is simpler and more rapid, because the consideration of the radioactive equilibrium and the chemical operation are unnecessary. The new method was applied to the analysis of deep well boring cores obtained at Higashikurume City in Tokyo, and the radioactive equilibrium of uranium series in the cores was discussed. As the results, it has been known that in the sandy and the silty cores, 226Ra/238U ratios are 2.4 and 1.7, respectively, and214Bi/226Ra ratios are 0.29 and 0.46, respectively.
It has been shown that the fluctuation of background spectrum of γ rays measured by pure germanium detector is caused by the variation of atmospheric radioactivity (222Rn, 220Rn and their daughters) . In order to diminish the fluctuation, nitrogen gas from the cryogen tank of the detector is flown into the lead vessel for shielding natural radiations. With the aid of the gas flow, peak counts of γ rays from daughters of222Rn and220Rn in the background spectrum can be so decreased that their fluctuations become within statistical uncertainties. The fluctuation of the total count (0-2800 keV) also becomes within the statistical uncertainty although the decrease of the count by the gas flow is at most 4%.
The natural abundance of15N (expressed as δ15N per mil relative to air N2) in the tissues and the change of15N abundance during the digestion processess in cattle, pig, and goat were investigated. The15N abundances of cattle tissues differed by about 3.5‰ with high values in heart, urinary bladder and diaphragm. The ages of cattle did not affect on the15N abundances of liver and kidney in cattle. The15N abundances of urine were lower, and those of feces were a little higher than the values of diets in cattle and pigs. The δ15N values of milk and blood were higher than the value of diets. Two peaks of15N abundances at forestomach and caecum were observed during the digestion processes of diet in goats. The mechanisms of the variation of15N abundances in animal bodies were briefly discussed.
Serum neuron-specific enolase (NSE) levels were studied in 105 patients with malignant neoplasms (lung cancer 38, others 67) , 13 patients with various benign diseases and 7 healthy adults. The mean serum NSE level in adult control subjects was 7.4±0.8 ng/ml, and cut of level was decided 10 ng/ml. Serum NSE levels were elevated in 14/38 (37%) of patients with lung cancer and in 14/ 67 (21%) of patients with the other malignant neoplasms. In patients with benign diseases, serum NSE level was elevated only in one patient with pituitary adenoma. In 7 patients with small cell lung cancer, the positive rate was higher (86%) than in those with non-small cell lung cancer (26 %), and serum NSE levels were higher than 25 ng/ml except one case. There was no correlation between serum NSE and CEA (carcinoembryonic antigen) levels in patients with small cell lung cancer, also in patients with lung cancer. The measurement of serum NSE level seemed to be useful for diagnosis in patients with small cell lung cancer.