Robert R. Landolt

Radionuclide content of and 222Rn emanation from building materials made from phosphate industry waste products.

The radionuclide content and 222Rn emanation coefficients of selected construction materials were determined. The materials were analyzed for 226Ra, 228Ra and 40K by gamma-ray spectrometry. Mineral wool insulation, which is made from Tennessee phosphate slag, and commonly used insulation, which is made from blast furnace slag, had similar concentrations of these radionuclides. Concrete blocks made with phosphate slag had enhanced 226Ra and 228Ra contents when compared to ordinary concrete block. The mineral wool insulation materials which were examined had emanation coefficients that were a few (2-6) times 10(-3). All other materials had emanation coefficients that ranged from 6 X 10(-4) to 4 X 10(-2).

The effect of diagnostic-quality X-irradiation on the developing postnatal rat retina.

Abstract The morphological effect of diagnostic-quality X-rays (140 kVp, 2·35 mm Al h.v.l.) on the developing postnatal rat retina was studied by the use of light and electron microscopy. Different litters of postnatal rats were exposed to 100 rontgens (R) of X-rays on each of the first seven days of life (day 0 through day 6, day 0 being the day of birth). Examination with light and electron microscopy on day 8 and day 14 revealed that the postnatal retina was insensitive to the induction of permanent retinal injury at the 100 R exposure level. No visible abnormalities that could be attributed to the effect of the irradiation were demonstrated in any of the retinal layers. Animals exposed on postnatal day 3 or day 4 to 200, 300, or 500 R of diagnostic-quality X-rays demonstrated severe injury within the outer layers of the sensory retina. The types of developmental lesions observed included (1) generalized dysplasia of the outer nuclear layer, (2) clusters of aberrant receptor cells within the photoreceptic inner and outer segments, (3) foci of apparent agenesis of the inner and outer segments and of the outer plexiform layer, and (4) the presence of an extra fiber layer within the inner nuclear layer. It was concluded that a threshold exposure exists for diagnostic-quality X-rays which is between 100 and 200 R, and that the rat retina is considerably more radiosensitive on postnatal day 3 than on postnatal day 4.

Studies on the toxicity of rhodium trichloride in rats and rabbits

Abstract Rhodium trichloride was found to be a substance of low toxicity when administered to rats and rabbits. The LD50 for rhodium trichloride administered by a single iv injection to the adult male Sprague-Dawley rat was 198 mg/kg (184–212) and to the adult male New Zealand white rabbit was 215 mg/kg (138–336). Histopathological studies involving the major organs of rats and rabbits revealed no pathological changes.

Barium Additives As Diesel Smoke Suppressants

The body of information presented in this paper is directed to those individuals concerned with the emission of smoke from diesel engines. A series of tests was performed on a Petter Type AA1 diesel engine using barium smoke suppressant additives. An Andersen cascade type sampler was used to collect samples and thus study the effect of the additive upon the total smoke emission, smoke size distribution and smoke composition. For a portion of the tests radioactive barium (133Ba) and scintillation counting techniques were used. Type 1-D fuel was used for all tests. Baseline tests were performed to determine the smoke emission characteristics using nontreated fuel, 0.5% by volume of Bryton additive, and 0.75% by volume of Lubrizol additive. For the radioactive additive, tests were conducted using dosages of 0.13%, 0.26%, 0.41%, and 0.82% by volume. The results of these tests revealed that the additive does not alter the particle size distribution, but the total mass emission from the engine is reduced by app...

An intercomparison of whole-body counters at participating region III nuclear power plants

Seventeen Region III nuclear stations originated and participated in an intercomparison study of their whole body counting procedures using the same calibration standard. The first phase of the study involved transporting a phantom containing four reactor-produced radionuclides and 40K to each plant. The plant staff were asked to follow all procedures applicable for a human subject including routine and investigative counts, if necessary, and to provide a printout of the results to the project investigators. The results from each plant were normalized for intercomparison by calculating the ratio of the reported activity to the actual activity after correcting for the appropriate amount of decay to the time of the count. Five plants reported 60Co values outside 1 standard deviation (SD) of the mean for 60Co and one plant did not detect the presence of 60Co. According to previously established procedures, these six plants were revisited after a period of time in which internal recalibration and corrective actions could be made. Four of the six plants had results which were still outside 1 SD of the mean for the original study. A final report in coded form to protect plant anonymity was provided to those stations to guide them in making further improvements, if they chose to do so.

The metabolism of 252CfCl3 in the rat and the effect of in vivo DTPA chelation therapy.

AbstractThe retention, distribution, and excretion of 252CfCl3 after intraperitoneal, intravenous, and intratracheal injection into rats is described. The effectiveness of DTPA chelation therapy in removing 252Cf from the body after it has been injected intratracheally is also reported. Following in

AN α-PARTICLE AUTORADIOGRAPHIC METHOD FOR QUANTIFYING THE INHIBITION OF ACETYLCHOLINESTERASE AT THE MYONEURAL JUNCTION

An existing histochemical method was adapted to α-particle autoradiography to provide a means of quantifying acetylcholinesterase inhibition at myoneural junctions. The α-particles were emitted from polonium 210 which was present in the precipitate after staining. A technique was designed for counting areas of dense α-particle tracks on the autoradiograms which corresponded to sites of acetylcholinesterase activity. An experiment was performed which showed that the track production rate was consistent for several diaphragm sections when incubated under identical conditions with no inhibitor. Tissue sections of this type, representing zero inhibition, were used as controls for inhibitor studies. It was also demonstrated that the track production rate was constant during the different exposure times used in the inhibition study. Diisopropylfluorophosphate was used to evaluate the autoradiographic method of quantifying acetylcholinesterase inhibition. A plot of log inhibitor concentration against percentage inhibition resulted in a smooth sigmoidal curve which is typical of irreversible inhibitors.

An investigation of a composite neutron activation dosimeter.

The feasibility of a neutron dosimeter containing several neutron activation detectors incorporated into a single composite was studied. The elements investigated in the composites were Au, Mn, Nay In, Cu, W, Co and Mo. It was found that the values of the neutron spectrum characterization parameters placed these elements into four groups and that certain pairing combinations gave better results than others. The activities of the neutroninduced radioactive products were measured with a Ge(Li) gamma ray spectrometer. Analysis of the gamma ray spectral data leading to calculations of the neutron fluence rate and dose equivalent was performed by computer. Potential applications include interstitial or intracavitary dosimetry for neutron radiotherapy, dosimetry of neutrons produced by neutron generators, and use in criticality dosimeters.

An inexpensive method for preparing freeze-dried sections of tissue for autoradiography

Abstract An inexpensive method is presented for preparing thin-section autoradiograms of diffusible substances by freeze-drying and osmium tetroxide vapor fixation of tissue. The unit can be easily constructed, occupies a minimum of space, and should be within the budget of most research laboratories. Both thin sections for light microscopy and ultrathin sections for electron microscopy can be prepared with the apparatus. Due to thinness of sections, the apparatus is best utilized for autoradiographic studies of tissue where there is a significant concentration of the isotope being studied.