As a novel application of 14 Me V neutron generator, the possibilities of hydrogen determination in hydrocarbons with recoil protons are discussed. High energy-recoil protons are produced from the collisions of the fast neutrons against the hydrogen nuclei. A mixture of hydrocarbon and boric oxide (B2O3) powder which has a large activation cross section for the protons was irradiated with the fast neutrons, and the activity of the powder was counted after removing the hydrocarbon from the powder. Half life of the boric oxide was about 20 minutes. This fact suggests that the reaction would mainly be caused by115B (p, n) 116C Specific activity (A) of the boric oxide is shown as follows. A=k ρ WH where k is constant, ρ is hydrocarbon density, and WH is weight fraction of hydrogen in hydrocarbon. It would be possible to obtain hydrogen content by the measurement of A, because a simple estimation of ρ with hydrometer can be done.
The effects of electron beam irradiation on p or n channel enhancement type MOS transistors, both prepared by the dry oxidation method have been investigated. The threshold voltage VT. shifts to negative side with the increase of irradiation dose. The result can be explained by the positive charges accumulated at the SiO2-Si interface. At the doses beyond 1014elecrons/cm2, however, the threshold voltage shifts to positive side with the increase of irradiation doses. The result can not be explained by the positive charges only.In order to explain the result satisfactorily, the idea of“electron-trapping centers”has been introduced. The effective length (distance from SiO2-Si interface) over which the positive charges collect was estimated at 410Å.
Sixty-nine cases including the hyper-, eu- and hypothyroid patients were studied using the Res-O-Mat and the resin sponge uptake (RSU) T3-kits. The index resulted from Res-O-Mat was well correlated with that from RSU, both showing the equal usefulness for the in vitro test of thyroidal function. The kits of different lot numbers were examined using the frozen serum of 4 cases in order to check the reproducibility of the test. The results obtained by the same frozen serum were varied to some extent; the deviation of the index was 2.5 to 11.0% with the resin sponge uptake kits and 2.5 to 3.8% with Res-O-Mat. The experiment was performed to see the effects of the incubate time on the index and it was suggested that the optimum incubate time would be 60 to 90 minutes.
67Ga-citrate is used for the clinical scanning of the malignant tumor, but the mechanism of its affinity for the tumor is unknown. In order to investigate the mechanism of the accumulation of67Ga in the tumor, experiments were carried out as follows. Five chemical forms of67Ga-citrate (carrier-free) , 67Ga-citrate (containing carrier Gacitrate) , 67Ga-nitrate (carrier-free) , 67Ga-nitrate (containing carrier Ga-nitrate) and67Ga-EDTA (carrier-free) were prepared. Their affinities for the malignant tumor were examined. These five preparations were injected intravenously to the rats which had subcutaneously transplanted Yoshida Sarcoma and these rats were sacrificed 3 hours, 24 hours and 48 hours after the injection. The radioactivities of the tumor, blood, muscle, liver, kidney and spleen were measured by a well-type scintillation counter. The retention values (% dose per g tissue weight) in the tumor, blood, muscle, liver, kidney and spleen were calculated. 67Ga-citrate (carrier-free) and 67Ga-nitrate (carrier-free) have very close affinities to the malignant tumor and their retention values in the tumor were approximately constant during 48 hours. Their excretion into urine was slower than other three preparations. The affinities of67Ga-citrate (containing carrier Ga-citrate) and 67Ga-nitrate (containing carrier Ga-nitrate) for the tumor were weak and the excretion into urine was faster than those of carrier free. 67Ga-EDTA was rapidly excreted into urine and its affinity for the tumor was weak. Besides, the experiment with rats which had intraperitoneally transplanted Yoshida Sarcoma showed that67Ga-citrate (carrier-free) and67Ga-nitrate (carrier-free) were taken up considerably by Yoshida Sarcoma ascites cells. From these experimental results, it may be deduced that a suitable chemical form of67Ga has strong affinity for tumors. 67Ga-nitrate becomes gallium-ion in water, and it is known that67Ga-citrate becomes gallium-ion when it was diluted with the adequate amount of water. Therefore the chemical form suitable for the selective uptake by tumor cells should be carrier free and able to become gallium-ions easily in the body. Chemical properties of gallium were also studied. The binding capacity of gallium-ion to protein is not strong, but its binding capacity to glass is very strong. It is likely that the gallium-ion is either physiologically necessary for cancerous cells, or, if not, it has specifically strong affinity for tumors for unknown reasons.