The cross correlation method was tried to apply to determine an unknown energy spectrum of γ-rays from observed data using a particular γ-ray detector. This method is as follows: taking the response of the detector for a monochromatic γ-rays as the search spectrum, the cross correlation function between the search spectrum and the data spectrum is computed. The application of the cross correlation method to the observed results enables to determine the energy spectrum of γ-rays using an organic scintillator. The measurements are performed for γ-rays of radioactive sources with energy over a range from about 0.5 MeV to 1.8 MeV. As compared with the both methods, the response matrix method and that using Fourier transformations, the special merit of this method is that the computing time is very short because the process of computation is simpler than those for the former two methods. For example, the time for processing data obtained by a 400 ch. detector is less than 10 sec by using the FACOM computer model 230-60. The resolving power by this method-the FWHM value of the peak was in the range from -25% to -90% for the change of energy of γ-rays-was poorer than that by using an inorganic scintillator such as NaI (Tl) . However, this problem will be improved with devisery of the shape of the search spectrum and of the process of the computation.
The present hygrometer is devised on the principle that the β-ray scattering by the metal surface decreases when the surface is covered by dew. This decrease of β-ray scattering is caused by the decrease of the effective atomic number of the scattering surface material. Carbon-14 and gold plate were used as the β-ray source and the metal, respectively. The counting rate due to scattered β rays and the temperature of the plate surface were recorded against time. The two temperatures at which the dew begins depositing and disappearing were detected in the experiments and decided the same dew-point. This hygrometer is useful to prevent supersaturation, because numerous condensation nuclei are formed by β rays and the rough finish of the plate surface makes the formation of dew easy. The hygrometer is also free from the errors owing to the incidental rise of the surface temperature caused by illumination which is indispensable for the mirror type hygrometer. The dew-point could be measured to an accuracy of 0.5°C, i.e. 2% in humidity, at room temperature.
An131mIn generator using zirconium tungstate was prepared. On mixing aqueous solutions of zirconium oxychloride and sodium tungst ate a white precipitate was formed which on drying gave a semi-transparent granules. Zirconium tungstate was hard and glassy inorganic ionexchanger suitable for column operation. X-Ray diffraction pattern of zirconium tungstate was amorphous. The long-lived113Sn was loaded on the column and the short-lived daughter113mIn was eluted out rapidly with 0.04N HCl. In each milking sequence with 4-6ml of 0.04N HCl, the leakage of113Sn was found to be less than 10-6times the original activity and the yield of113mIn was about 50 percent of the113mIn on the generator. The breakthrough of zirconium and tungsten into eluates from the generator, measured by the microchemical spot tests using the ion-exchange resin, was 0-0.3μg Zr/mland 0-4.0μgW/ml, respectively.
A labeling method with tritium at the 6th position, a biological inert position, of naphthoquinone nucleus o f vitamins K was studied. The catalytic tritiation of 2-methyl- 6-bromonaphthalene on Pd-black was found to be successful for labeling selectively the 6th position. The position of tritium label was confirmed by assignning the IR and NMR spectra of deuterated model compounds which were synthesized by the same procedures as tritiation. And it was also found that H3PO4was more useful co-catalyst for the condensation of naphthoquinone nucleus with the side chain of vitamin K2 (20) .
14C-Catechols and other radioactive metabolites in the tissues and 6 hour-urine of mice given14C-L-dopa orally were determined quantitatively. The concentrations of total radioactivity and14C-catechols in various tissues except the adrenal reached a peak at 20 minutes after administration and thereafter decreased gradually. 14C-Catechols in the adrenal kept high concentration until 6 hours after administration. The great part of14C-catechols in the adrenal was found to be due to14C-catecholamines. The percentage of14C-cateeholamines in the brain was the highest among various tissues except the adrenal. Unchanged14C-L-dopa accounted for only a few percentages of the radioactivity in various tissues. Of the radioactivity excreted 6 hour-urine, 44% was homovanillic acid, 38% was conjugated metabolites, and 15.1% was catechols. The catechols consisted of adrenaline (3.2%), noradrenaline (4.1%), dihydroxyphenyl acetic acid (2.8%), dopa (1.75%) and dopamine (1.45%) . Whereas conjugates consisted of dopa (12.8%), homovanillic acid (6.1%), dopamine (5.6%), adrenaline (4.3%), dihydroxyphenyl acetic acid (2.2%), noradrenaline (2.7%) and unknown metabolites (3.9%) .