The performance of a windowless continuous channel electron multiplier which utilizes a strip of semiconductor material (Si) for detection of some kind of radiation (a, β, γ) is described. The principle of the detector operation is the cascade reflection of the secondary electron multiplication between the two continuous silicon resistance strips. The silicon strips of the dynode obtained the resistivity of 106-107Ω/cm by reactor irradiation. A current gain of 109can be realized with the detector for an overall voltage of approximately 3kV. The background counting rate of the detector, at room temperature and in typical operation, is less than 1 count/hr for the pulses whose voltage height is over 0.5 mV across the load resistance.
The formation of amino acid from a-ketoglutaric acid and ammonia aqueous solution by60Co γ-ray irradiation has been studied. The irradiated solution was analyzed by electrophoretic method and amino acid analyzer. Glutamic acid was identified and estimated spectrophotometrieally. The yield of glutamic acid was found to be dependent on the radiation dose and the concentration of a-ketoglutaric acid and ammonia. The effect of dose rate and temperature on the yield is not significant. The reaction mechanism was proposed as the reductive amination induced by the irradiation.
Neutron activation analysis was employed in an effort to directly determine free thyroxine (free T4) in sera of normal subjects and patients with various thyroidal disorders. Nine ml of serum was dialyzed in 114 ml of phosphate-buffered saline at 37°C for 22 hours. and 100 ml of the dialyzate was poured onto anion-exchange resins in three successive columns to separate free T4. Together with iodine standards, the free T4 obtained was irradiated in the pile at a thermal neutron flux of 4×1012n/cm2·sec for 60 minutes. The induced 128I was separated by (1) acid digestion and distillation, (2) extraction with carbon tetrachloride and (3) precipitation with silver nitrate. This process reduced inorganic iodide and iodotyrosine contents to a negligible amount and also eliminated radiochemical impurities. The estimated values of free T4 for hyperthyroidism were about the same as those obtained by the tracer method, while the values for normal subjects and hypothyroidism were considerably higher than by the tracer method. The possible reasons for the high values were discussed.
In order to study the penetration, distribution and excretion of the insecticides, wholebody autoradiographic technique was applied to cockroach. At a definite time after the topical application of BHC (γ-isomer, 3μg/5μl benzene, 14C 0.3μCi) (β-isomer, 6.5μg/10μl benzene, 14C 0.8μCi) and nicotine (41μg/10μl ethanol, 3H 100μCi) on the back side of the abdomen of the adult male american cockroaches, the anesthetized insects were buried in the methylcellulose paste on the microtome stage, and were frozen rapidly in the dry-ice-n-hexane bath. After being frozen completely, the whole body was tape-sectioned and the dried sections (top thick) were brought into contact with X-ray film. Some of the results observed are as follows. 1) β-BHC penetrated much more slowly than γ-isomer. 2) In 15 minutes, γ-BHC reached almost all parts of CNS. crop and gizzerd, although major quantity of the dose remained in the applied area. 3) At later times, the major part of the penetrated β- and γ-BHC was found in the mid gut, gastric caeca, and at the walls of the crop. 4) Very little, if any, radioactive γ-BHC was observed in the area of the fat boby. 5) The accumulation in the peripheral region, but not inside, of the CNS was observed for γ-BHC, although its concentration was not very high. 6) Nicotine penetrated into CNS very easily, and the concentration difference between inside and in peripheral region was very little. This is in contrast to the case of γ-BHC described above. 7) Nicotine penetration and distribution throughout the body were very rapid. In the earlier stages, there were clearly observed secretion images at the walls of the digestive organs.
Blasticidin S, an antifungal substance, showed inhibitory effect on Chlorella pyrenoidosa Chick and Nicotiana tobacum L, , but no effect was observed at the concentration less than 1 ppm and static effect at the concentration less than 100 ppm. The inhibition of14C-amino acids incorporation into protein fraction occurred on the cell free system rather than the intact cell of chlorella, and the inhibition was specifically observed on the protein synthesis of 15, 000×g-ppt fraction containing chloroplasts and mitochondria. The similar results were obtained by the studies of the cell free system of Nicotiana tobacum.