Immunology has been extensively investigated for recent ten odd years and also has shown marked advance. It has been made known that the immune response as well as the immunologic surveillance is concerned with carcinogenesis and ageing. On the other hand, it is hardly necessary to mention that radiation carcinogenesis and shortening of life span are very important problems in the late effcets of radiation. Many investigations pertaining to the effect of radiation on immune response have been reported during a past few decades. Then, this review considers following two subjects: One is the immune response concerned with carcinogenesis and ageing, and another is the interrelationship between radiation and the immune response from two perspectives. 1) The effect of radiation on antibody production and cellular immunity. 2) The radiosensitivity of lymphocyte subpopulation.
An experiment was made to test the performances of the respirator canisters under both steady and simulated respiratory flow conditions, using a mechanical breathing simulator and a sodium chloride aerosol as the test aerosol. Tested were eighteen commercially available canisters, imported and domestic ones. Efficiencies and inhalation resistances of the canisters are summarized as a function of inspiratory flow rates for both test flow conditions. Increases in penetration and resistance under the pulsating flow are observed as being compared with those under the steady flow at same minute volume. Based on the data, a simplified method is proposed for roughly estimating performance under respiratory pulsating flow through a steady flow measurement. Comparison is also made between the present results and nominal efficiency of each canister.
Nondestructive uranium analysis by epithermal neutron activation was confirmed to be utilized as a simple and reliable method for the determination of uranium in environmental materials such as surface soil and river sediment. In the case of surface soil, samples to be irradiated with neutrons are prepared in the following manner so that they may be satisfactorily represent the actual mean chemical compositions. From 2 to 3kg of surface soil having been passed through a sieve to remove particles larger than 1mm in diameter, about 5g are taken and pulverized in a mixer-mill. About 100mg of the pulverized soil are accurately weighed and sealed into a polyethylene bag. The samples thus prepared are wrapped in a cadmium foil and irradiated with reactor neutrons. Gamma-ray spectra of activated samples are collected 4 to 5 days after the neutron irradiation. The detection limit was found to be about 0.1ppm for usual soil samples.
In order to study the behaviors of uranium series nuclides in soil, a soil sample, which was derived from weathering of granite rock, was separated into several particle size ranges, and each of the separated fractions was analyzed for the concentrations of 238U, 230Th, 226Ra and 210Pb by means of γ-ray spectrometry with Ge(Li) detectors. The activity ratios of 230Th/238U, 226Ra/238U and 210Pb/238U were found to be larger than unity for all the size ranges; the ratio of 230Th/238U was especially high, reaching 3 to 5. It was further found that in a size range smaller than 0.15mm the concentrations of the four nuclides increased with decrease in particle size. It is pointed out that the size of soil particles as well as the disequilibrium between the uranium series nuclides can be important factors which should be taken into consideration when monitoring of radioactive contamination in soil.
The M. S. program in health physics in the Republic of China started at the Graduate School of National Tsing Hua University on September, 1, 1975. This program was evolved from the experiences gained during the past decade. Several training courses and inspections of radiation facilities throughout Taiwan have been held year by year. The newly established M. S. program will enable one to work in three distinct areas: nuclear power plant, hospital, and radiation biology with reference to radiation protection. Basic scientific knowledge and experimental technique are equally emphasized. The student should study at least for two years and submit a M. S. thesis to complete his degree program.