A low background end window type GM counter with a short anode wire of 1.1 cm length was constructed and it was filled with counting gas which was the mixture of 89.4% helium and 10.6% isobutane. The gas pressure was about 80-150 mmHg. And the plateau characteristic was measured by introducing 3-ray beam from a137Cssource through the center of the window and parallel to the anode wire. Then it was found out that the plateau had large slope. Although there can be some reasons for the slope, considering the short anode wire and the low gas pressure which result in a few ionizing events in the counting volume, we supposed that the large slope would be due to the decreasing of the counting loss based on the increasing of the counting volume along the counter axis with increasing of applied voltage. Then in order to decrease the variation of the counting volume with applied voltage it was tried that the correcting ring was inserted at the end of the anode support to make the electric field near the anode wire uniform through the entire length of the wire. As a result the plateau characteristic was fairly improved and it was shown that the correcting ring was effective to decrease the dependence of the counting volume on applied voltage. Then in order to make sure that the electric field was improved by the ring some experiments were performed. As a result it was found that the correcting ring absorbed well electric lines of force which originated near the end of the anode support and that it fairly uniformed the electric field near the anode wire all over.
To produce the useful quantities of52Mnin carrier free state, 3Heor a particales bombardments on natural chromium metal target were thoroughly studied. The activities of52Mn, 54Mn, 56Mnand other nuclides were measured by the calibratedGe (Li) detector connected with a multi-channel pulse height analyzer. The excitation curves and thick-target yield curves for the formation of the three manganese radionuclides were obtained. It was found that 52Mn was mainly produced by (3He, p2n) reaction on52Cr, the cross sections of which reached to the maximum value of 220 mb at 33 MeV3Heparticles. On the other hand, that of54Mn, an undesirable accompanied nuclide, was found to be 80 mb at 18 MeV. From the excitation curves and operating conditions of the cyclotron, 40 MeV of3Heparticles was decided as the most suitable energy to give useful quantities of52Mn.It can give the yield of 156 and 1.1μCi/μAh of52Mnand54Mn, respectively. Thus52Mnseparated in carrier free state was estimated to contain about 0.7%54Mnactivity at the end of bombardment. 52Mncan be separated and purified by anion exchange followed by distillation from the dissolved solution of the bombarded chromium target and also by anion exchange from52Fesolution which contains52Mnas the decay product. In the latter case about 1μCi of52Mncan be obtained from 1 mCi of52Fe, but free from54Mn. Onαparticles bombardment, 52Mnwas mostly produced by (α, pn) and (α, p3n) reactions on50Crand52Cr, respectively. The maximum cross sections for the formation of52Mnand54Mn were found to be 35 mb at 27 MeV and 490 mb at 18 MeV a particles, respectively. These two nuclides were produced with yield of 22 and 6μCi/μAh, respectively, at 40 MeV αparticles. The ratio of54Mnactivity to52Mn at the end of bombardment was found to be 27.3%, which was fairly larger than that on 3He bombardment. It was proved that3Hebombardment was superior toαbombardment on natural chromium. The yield of52Mnand the quantities of other by-produced nuclides were compared with those reported on proton or deuteron bombardments. Finally it may be said that as a conclusion 40 MeV3Hebombardment on natural chromium metal was superior in giving useful quantities of52Mnwith reasonable high yield of 156μCi/μAh and only accompanied with smallest quantities of54Mnunder 0.7% at the end of bombardment.
When the embryos were excised from barley seeds and incubated in nutrient medium containing 2, 4-D, radioactive phosphate was incorporated into DNA, soluble and ribosomal RNAs, as well as into other heterogeneous RNAs. The kinetics of nucleic acid synthesis revealed that in the presence of 2, 4-D the synthesis of RNAs were induced in the regions corresponding to ribosomal RNA.
A method of the determination of serum iron binding capacity was investigated using radioactive iron-59. A chemical TIBC kit“Fe test Wako”was used as reagents. Radioiron59Fe was added to ferric chloride solution. 0.5 ml of serum was incubated to59Feferric chloride (3μg Fe) solution during 10 minutes at 37°C. After the first counting of59Feactivity (A cpm), 0.15g of magnesium carbonate was added to the mixture which was kept stand at room temperature for 30 minutes. After centrifugation, 1 ml of supernatant removed to another counting vial with the same diameter and diluted to the same volume of the intial mixture and counted the59Feactivity again (B cpm) . Then UIBC (μg/dl) =B×2/A×3×200 From ninety two to ninety seven % of 3μg unbound iron was removed by 0.15 g of magnesium carbonate under the presence of iron saturated serum. While, 59Fein unsaturated serum was not precipitated by the same dose of magnesium carbonate. There were no elution of59Fefrom the precipitate of magnesium carbonate and iron colloid mixture to the supernatant. The data obtained from this method showed excellent linearity and was quite steady for the changes of room temperature and for repeated determination. The correlation between the value of UIBC obtained from chemical and radioiron method by magnesium carbonate was significant. Mean normal value of UIBC by this method was 200.5±45.9μg/dl, 187.9±43.5μg/dl for male and 205.9±46.3μg/dl for female. Since this method has quite simple technique and gives correct value of UIBC, it is concluded that this method is suitable and excellent method for the determination of serum iron binding capacity.
A method of the determination of serum iron binding capacity using radioiron and resin sponge was investigated. The resin sponge was supplied from Dainabott Laboratory as“Irosorb-59”Kit. One ml of serum was added to a plastic tube which contained 6 ig of iron labelled with59Feas ferric ammonium citrate. After 10 minutes of incubation, the resin sponge was added to the tube and pushed it by special stick in order to remove the air.59Feactivity in the tube was measured (A cpm) before incubation of 60 minutes at 37°C. After the incubation, liquid layer was removed completely by suction using special designed stick. Two or 3 times of wash were repeated by distilled water with same procedure.59Feactivity of the sponge in the tube was counted (B cpm) . Then UIBC (μg/dl) =A-B×a*/A ×Fe (μg) ×100a* =absorption ratio UIBC values obtained from Irosorb-59 method showed significant higher than the values obtained from magnesium carbonate. The elution of radioiron in sponge due to washing by water was negligible. The absorption rate of sponge to 6, cig of unbound iron on the presence of iron saturated serum was 78-88%. 59Felabelled ferric ammonium citrate was incubated to serum. After the treatment of sponge, the electrophoretic pattern of the serum was observed.59Feactivity existed chiefly inβ1-globulin fraction but lot of radioactivity also existed in albumin andα1-globulin fraction. From these results, ability of iron absorption of resin sponge seemed to be somewhat weaker than expected. The treatment with 2 or 3 sponges to the same serum gave correct values of UIBC. Also, the use of corrected absorption ratio of resin sponge revealed moderately good results. However, in the serum which has very high or low UIBC, the values by this method showed somewhat different values compared with that of magnesium carbonate method. From the above results, it is concluded that this method is useful for the determination of UIBC in clinical samples.