Search Results
Abstract
Pulsed slow positrons were produced using a time-varying moderator bias with an interval of 82 ns; 97% of the positrons were compressed within 2 ns width at the target position. Both the positron annihilation lifetime and Doppler broadening of the positron annihilation radiation (DBPR) of polytetrafluoroethylene (PTFE) were measured as a function of the incident energy of slow positrons. It was shown that the lifetime and intensity of the long-lived component of positron annihilation are independent of the positron incident energy above 1.2 keV. However, the width of the Doppler-broadened annihilation γ-ray increased in the energy region below 1.2 keV.
Abstract
Thirty-three sediment samples from four shoreline and three sea positions in a defined sampling grid around the Bushehr Nuclear Power Plant (BNPP) have been taken over six sampling periods during 1996-1997. Elemental analysis of the samples has been performed with neutron activation and concentrations of seventeen elements have been obtained. Cross-correlation analysis has been carried out and four categories of related elements have been defined.
Abstract
Copper-64 was produced as a by-product of 55Co via 64Ni(p,n)64Cu by 15 MeV proton bombardment of natNi resulting in a thick target yield of 5.31 MBq/μAh (143.5 μCi/μAh) and a radiochemical separation yield of 95% (radionuclide purity >97% after 25 hours of bombardment). Rituximab was successively labeled with [64Cu]-CuCl2. N-succinimidyl-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA-NHS) was prepared at 25 °C using DOTA and N-hydroxy succinimide (NHS) in CH2Cl2 followed by the addition of 1 ml of a Rituximab pharmaceutical solution. Radiolabeling was performed at 37 °C in 3 hours. Radio thin-layer chromatography showed an overall radiochemical purity of 90–95% at optimized conditions (specific activity=30 GBq/mg, labeling efficacy; 82%) using various chromatography systems. The final isotonic 64Cu-DOTA-Rituximab complex was passed through a 0.22 μm filter and checked by gel electrophoresis for radiolysis control. Stability of the final product was checked in the formulation and in presence of human serum at 37 °C.
Summary
The synthesis of the seven 99mTc-labeled nitrophenol radiosensitizers (N2OS chelates) was undertaken for evaluation of their biostability in vitro as possible hypoxia tumor imaging agents. The title compounds (2-7)were successively synthesized, characterized, and finally radiolabeled (99mTc-NaTcO4, stannous chloride, pH 10) to obtain the new complexes (8a-8f) for evaluation. The purity and stability of the final complexes (in human and rat serum) were evaluated by chromatographic methods (radio-TLC, ITLC, HPLC). The most stable complex over 6 hours was shown to be 99mTc-labeled 3-[3'-N-(2”-hydroxy-5”-nitrobenzylamino)-2'-propanol]-1-(4'-methyl)thiourea (8e). Biodistribution studies of 8ein tumor-bearing rats are under investigation.
Abstract
A single crystal of heptaaqua-p-nitrophenolatostrontium(II) nitrophenol (HNSN) was grown, and the structure was confirmed by UV–Vis–NIR, FT-IR, FT-NMR, and high-resolution X-ray diffraction (HRXRD) analyses. The dielectric loss, dielectric constant, and the mechanical strength of the crystal have already been reported. The dynamic, non-isothermal thermal analysis was carried out at different heating rates, and TG and DTG data were used for the interpretation of the mechanisms and kinetics of decomposition by means of a model fitting method, Coats–Redfern equation, and a model-free method, Kissinger and Flynn–Wall method. The values of activation energy (E) and the pre-exponential factor (ln A) of each stage of thermal decomposition at various linear heating rates were calculated.
Abstract
Ochre is a significant material in Aboriginal Australian cultural expression from ceremonial uses to its application on many types of artifacts. However, ochre is a complex material, with associated surrounding minerals potentially challenging the overall analysis. In recent literature several studies have attempted to characterize ochre by a variety of techniques to understand procurement and trade. However, ochre is difficult to differentiate on major elemental or mineralogical composition and requires a detailed analysis of its geochemical “fingerprint”. Neutron activation analysis (NAA) provides the high sensitivity (sub-ppm), precision and accuracy in multi-elemental analysis required for ochre. The elements of interest for ochre generally include rare earth elements (REEs) and certain transition metal elements as well as arsenic and antimony. Data from relative comparator NAA (MURR, University of Missouri, USA) is compared with data from k 0-NAA OPAL (ANSTO, Lucas Heights, Australia). A discussion of the two methods will be examined for their utility in “fingerprinting” the provenance of ochre. The continuing importance of NAA to archaeometry will also be discussed.
Abstract
The radioactive concentrations of radionuclides were measured in the soil and groundwater below the 12 GeV proton beam-line tunnel at KEK. Various long-lived radionuclides, (7Be, 22Na, 46Sc, 54Mn, 60Co, 134Cs, 152Eu and 154Eu) were observed in the soil samples by 
-ray spectra measurements, and 3H was also detected by liquid scintillation counting. On the other hand, 3H, 22Na and 54Mn, which were leached from the soil were measured in the groundwater below the EP2 beam line. 3H and 22Na were also found in slight amounts in groundwater collected in a well dug beside the East Counter Hall. From a comparison with the radioactive concentration in soil and groundwater, the order of the leaching percentages were 3H>22Na>54Mn. This tendency was in agreement with an experimental result of the RI laboratory.
Abstract
Thermal neutron analysis (TNA) technology has been used for the non-destructive detection of explosives. The system uses a relatively weak 252Cf neutron source (1.03·107 n/s) and two 3"×3" NaI(Tl) detectors. The presence of explosives is confirmed via detection of the 10.83 MeV prompt gamma-ray associated with nitrogen decay. The MCNP4A code was used to simulate the neutron and gamma transport through the system. The thermal neutron flux in the activation position was measured using gold and indium foils. The measured thermal neutron flux was lower, by not more than 9.5%, than that of simulation. In this report the results of the preliminary tests on the system are described.
Abstract
The irradiation of atmospheric air with high-energy protons has been performed at the 12 GeV proton synchrotron. The specific activity of 13N, one of the principal airborne radioactivities, was measured as a function of the irradiation time at a dose rate of about 6·1016 eV/g/s, and compared with the calculated values. The predominant chemical species of 13N produced were found to be 13N2and 13NO2. Their proportions were approximately 55% for 13N2 and 45% for13NO2, being almost independent of the irradiation time. Smaller quantities of 13NO and H13NO2 were also observed. Measurements of radiolytic products showed that ozone is a main product and that NO2predominates among the products of nitrogen compounds, including HNO2 and HNO3. The G-value for ozone formation in air was estimated from the experimental data as 6.4 molecules/100 eV.
Abstract
The aim of the work is to describe briefly the methodology for establishing and operating an internal dosimetry program in a complex waste processing facility, with special emphasis to the complexity of activities and problems and to the uncertainties in attributing doses from bioassay data. The purpose is not to make a fundamental study of the dosimetric models as such, but to give the viewpoint of the practical health physicist who is confronted with interpretation problems as the consequence of an intake of radionuclides. Some model parameters are discussed in relation to acute or chronic intakes. A practical contamination case is elaborated.
