Search Results
Abstract
An infrared furnace (ULVAC RHL-410P) was newly applied to the extraction of tritium from concrete samples. After studying the tritium recovery yield regarding temperature and time, the best extraction conditions were set to 800 °C (setting temperature) for 30 minutes under Ar-gas flow of 200 ml/min. Tritium was collected in two cold traps and transferred to a vial for liquid scintillation counting. It took about one hour for the extraction of tritium. Reproducibility and recovery yield of tritium were about 100% compared to the values obtained by the ordinary heating method using an electric furnace. Gamma-ray emitters and tritium of concrete samples collected from several accelerator facilities have been determined. The specific activity of tritium strongly correlated with that of 152Eu and 60Co, so it was found that tritium was produced by thermal neutron reaction by the 6Li(n,
)3H reaction. The results indicate that the tritium specific activity in concrete can be estimated from the 60Co specific activity obtained easily by 
-ray measurement.
Abstract
Gel generators based on Zn, Co, Ni, Mn and Pb tungstates were prepared as potential supports for the development of188Re radiopharmaceuticals. Factors which affected either the elution efficiency of188Re or the breakthrough of188W were examined.188Re was produced as perrenate when the generators were eluted with saline (0.15M NaCl) and different organic solvents. The elution yield of188Re decreased for the various gel supports as: Zn (75%), Co (60%), Ni (37%), Mn (24%), Pb (15%). When a 
tandem
system comprised of a chromatographic alumina column was utilized in combination with the gel generator the188W breakthrough was controlled to of the order of 10–6%.
Abstract
High-energy protons and neutrons produce various radionuclides in the air, mainly through the nuclear spallation of atmospheric elements. Air samples were collected from the EP-2 tunnel of the KEK 12 GeV proton synchrotron facility with a filter pack, which consisted of a membrane filter for aerosols, a Na2CO3-impregnated filter for acidic gases, and an activated carbon fiber filter for non-acidic gases. Sulfur-38 was found on the membrane and Na2CO3-impregnated filters, 38Cl and 39Cl were on the membrane, Na2CO3-impregnated, and ACF filters, and 82Br was only on the ACF filter. The results on the relative abundances of aerosol and gaseous acidic components have indicated that 38Cl produced by thermal neutron capture, which is the main reaction for 38Cl production in the EP-2 tunnel air, are likely not to be present as aerosol or acidic gas. This was similar to the case of 82Br produced by thermal neutron capture.
Abstract
Activation is one of the severe problems at the high-energy accelerator facilities. By using gamma-ray spectrometry and activation detector technique, we could obtain important information on (1) nuclear reactions, (2) energy spectra of secondary particles, (3) penetration behavior of secondary particles in shield wall, (4) historical record of beam loss occurred in the accelerator rooms. It was concluded that the technique and knowledge of activation analysis are very useful to solve the radiation protection problems at the accelerator facilities.
Abstract
Highly selective and sensitive γ-ray detection was performed by coincidence and anticoincidence event analysis after list-mode data acquisition using an HPGe spectrometer equipped with NaI(Tl) and plastic scintillation detectors. In order to obtain the most suitable detection of specific nuclides, coincidence or anticoincidence spectra could be freely constructed by extracting events with particular time and energy correlations. Although the detector arrangement of this system was the same as that of a typical Compton suppression spectrometer, background counts were drastically reduced and γ-rays of particular nuclides could be selectively detected by using γ-γ, γ-X, γ-X-X, and γ-β+ coincidences.
Abstract
The disodium, dilithium, dipotassium and distrontium forms of cerium phosphate were prepared from their corresponding mono-forms. The chemical content of these inorganic ion exchangers have been characterized by inductively coupled plasma (ICP) spectroscopy. The ion exchange properties of these cation exchangers, their chemical stability and selectivity for certain ions were investigated. It was found that, by introducing different salts into the reaction mixture used to prepare cerium phosphate, robust cation exchange materials of reproducible composition with a good cation capacity, and suitable for column use, are produced. All the ion exchangers with the exception of CeP (dipotassium) show excellent selectivity towards certain cations, thereby increasing the potential practical applications of these inorganic exchangers.
Abstract
For decommissioning of the cyclotron and electron synchrotron facilities, the residual radioactivity in surface and core samples of concrete, collected from various parts of buildings, was determined by gamma-ray spectrometry. It was found that the concrete samples were activated mainly by neutrons and that the major radioisotopes were 152Eu, 60Co, 134Cs, 22Na and 54Mn. The maximum activity induced by thermal neutron capture was observed at the depth of 10 cm in the concrete wall near the deflector of the cyclotron. Tritium was also produced by the neutron reaction, because its concentration was proportional to the activities of 152Eu and 60Co. The surface dose rates inside the accelerator room were also monitored to define the decontamination area. The surface dose rate was proportional to the residual radioactivity, such as 60Co. A careful evaluation was very useful in order to minimize the radioactive waste during decontamination.
Abstract
Hair samples were collected from 100 healthy people residing in Esfahan, Iran. The concentration of fourteen elements (Al, Br, Ca, Cl, Cu, Hg, I, K, Mg, Mn, Na, S, V, Zn) were determined by instrumental neutron activation analysis (INAA). The statistical results show that there are significant interrelations between some element such as: (Al-Mn, Al-V, Mg-Ca, Mn-V) and also there is no significant age correlation with any element. In addition, the results of this study are compared with the results obtained in England and New Zealand.
Abstract
A group of cyanoethylated amine (CEA) has been synthesized by carefully reacting triethylenetetramine with varying proportions of acrylonitrile. Such CEAs were utilized as hardener for the curing of epoxy resin. The effect of cyanoethylation of amine on their curing reaction with epoxy resin has been studied by differential scanning calorimeter (DSC). The processing temperature for the fabrication of composite is estimated from the DSC analysis with an approach to satisfy the logical selection of temperature for application of pressure during processing of a composite structure. The exotherm of such curing reaction (ΔH ex) and the degree of cyanoethylation (CEt) of the amine follow the relation ΔH ex = (324–68.40 CEt) J g−1.
Two sensitive and selective chromatographic methods were developed for determination of finasteride and tamsulosin hydrochloride in bulk powder and a pharmaceutical formulation. The first method was based on high-performance liquid chromatography (HPLC) separation of the cited drugs in the presence of the acid degradation product of finasteride. The separation was achieved using a C18 column (300 mm × 3.9 mm; 10-μm particle size) and a mobile phase consisting of 0.04 M ortho-phosphoric acid (pH 3.5 ± 0.2 adjusted with triethylamine) and acetonitrile (50:50, v/v). Quantification was achieved with ultraviolet (UV) detection at 215 nm. Linearity was in the range of 10.00–110.00 μg/mL and 2.00–44.00 μg/mL for finasteride and tamsulosin hydrochloride, respectively. Thin-layer chromatography (TLC)–densitometric method was achieved on an aluminum plates pre-coated with silica gel 60 F254 using toluene–ethanol–diethylamine (8:2:1.5, by volume) as eluent, and the R F values of tamsulosin hydrochloride and finasteride were 0.57 and 0.64, respectively. Quantification was achieved with UV detection at 250 nm for finasteride and 280 nm for tamsulosin hydrochloride. Linearity was in the range of 1.00–40.00 and 0.2.00–20.00 μg per spot for finasteride and tamsulosin hydrochloride, respectively. The results obtained were validated according to the International Conference on Harmonisation (ICH) guidelines. A statistical comparison between the obtained results and the results of a reported method was carried out.
