Search Results
Abstract
Aluminum levels of serum and red blood cell (RBC) were determined by instrumental neutron activation analysis (INAA) in 15 patients undergoing long-term haemodialysis. In the sample, aluminum was bombarded with thermal neutrons due to 27Al(n,γ)28Al and was determined by measuring 1779 keV gamma-ray of 28Al (T 1/2 = 2.24 min) with a HPGe detector. Phosphorus, causing an important interference by the fast neutron reaction, 31P(n,α)28Al, was determined by the photometric method to correct the net-area under the 28Al gamma-peak. The one-sample Kolmogorov-Smirnov test was used to control the normality distribution of the aluminum levels in serum and RBC. The results obtained were found to be in agreement with the serum aluminum determination performed by electrothermal atomic absorption spectrophotometry. The statistical results show a correlation between the aluminum levels of serum and RBC.
Abstract
A neutron porosity probe has been designed. The MCNP Monte Carlo code has been utilized to determine the various parameters of the probe. The probe response was simulated and compared with the experimental results with good agreement. Preliminary fieldwork was performed with acceptable data.
Abstract
Background soils from areas around the United States Department of Energy facilities in Oak Ridge, Tennessee were characterized as part of an environmental restoration project. The data obtained in this project were validated using guidelines from the Environmental Protection Agency (EPA) Contract Laboratory Program (CLP), when EPA methods were used. However, there are no final EPA guidelines for validation of data obtained using radiochemical analytical methods, so procedures for validation had to be developed. This paper will describe the validation guidelines that were developed for neutron activation analysis (NAA) data and discuss the regulatory basis for them.
Abstract
There is ample scope for modification of polyvinyl alcohol (PVA) to derive diverse range of properties because of the presence of hydroxyl group in its chain. In the present work, PVA has been modified to carboxymethylated polyvinyl alcohol (CPVA) — a carboxy-functionalized membrane material. Generally the cohesive energy density has incremental influence on the melting point and mechanical strength of a material but in this case of CPVA even though theoretical cohesive energy density of CPVA is lower than that of PVA but paradoxically its mechanical strength was found to be higher than that of PVA (∼202 vis-à-vis 207°C and ∼174 vis-à-vis ∼58 MPa, respectively). Calorimetric evaluation along with the energy balance concept have provided meaningful information to justify such paradoxical feature as a result of the dominating role of intermolecular hydrogen bonding in CPVA to compensate for its relatively lower cohesive energy density typically 0.05 J m−3/2. Thermal analysis has been made to examine the role of PVA and its carboxymethylated derivative (CPVA) towards moisture. It was observed that PVA membrane surface became sticky on exposure to water at 30°C for a period of 30 min, whereas under the same condition CPVA counterpart remained practically unaffected.
Summary
Due to interesting biological properties of palladium-thiosemicarbazono complexes, production of a 103Pd-labeled anti-cancer complex, i.e., [103Pd]-2-acetylpyridine 4N-methylthiosemicarbazone ([103Pd]-APMTS) was developed. Palladium-103 (T 1/2 = 16.96 d) produced via the 103Rh(p,n)103Pd nuclear reaction using natural rhodium target, was separated from the irradiated target material. Proton energy was 18 MeV with 200 mA irradiation for 15 hours (final activity 700 mCi of 103Pd2+, RCY>95%, radionuclidic purity>99%). The final activity was eluted in form of Pd(NH3)2Cl2 in order to react with 2-acetylpyridine-4 N-methylthiosemicarbazone to yield [103Pd]-APMTS. Chemical purity of the final product was confirmed to be within the accepted limits by polarography. [103Pd]-APMTS was prepared with a radiochemical yield of more than 80% at room temperature after 3 hours. The labeling reaction was optimized for time, temperature and radioactivity and ligand ratio. A mixture of APMTS and Pd activity in ethanol was heated at 90 °C for 3 hours followed by reverse phase SPE purification using C18 plus Sep-Pak. Radiochemical purity of more than 99% using RTLC and specific activity of about 12500 Ci/mol was obtained. The stability of the tracer was checked in the final product and the presence of human serum at 37 °C up to 3 hours. The partition coefficient of the final complex was determined by octanol : saline buffer distribution.
Abstract
For evaluation of radioactivity induced in the concrete samples from accelerator facilities, the residual radioactivity in concrete sample, collected from seven accelerator facilities, was determined by γ-ray spectrometry. The tritium was extracted by the heating method using an IR furnace, and measured with a liquid scintillation counter. It was found that the major radioisotopes activated mainly by neutrons in the concrete samples were 152Eu, 60Co, 134Cs and 3H. The concentrations of radioactivities induced by thermal neutron capture are the highest at a depth of 10 cm in the concrete wall. The correlation between tritium, 60Co and 152Eu activity was investigated by measuring many concrete samples for seven accelerator facilities. The results indicate that their activities are strongly correlated with each other. So it would also be concluded that the total activity in shielding concrete could be estimated on the basis of the activities of 60Co and 152Eu.
Abstract
In this study, a high catalytic activity of palladium nanoparticles immobilized on alumina (Al2O3) is reported for the industrially important reduction of aromatic nitro compounds to amino compounds. The palladium nanoparticles were immobilized on alumina by a simple physical precipitation method. The synthesis of palladium nanoparticles was done in ethylene glycol without using any external stabilizing agent. The composite particles exhibited good colloidal stability. The catalytic activity is investigated qualitatively by high performance liquid chromatography (HPLC) and quantitatively by photometrically monitoring the reduction of p-nitrophenol by an excess of sodium borohydride (NaBH4) in the presence of nanocomposites. The kinetic data could be explained by the assumption of pseudo first-order reaction with respect to p-nitrophenol.
Abstract
A bound state of positron (e+) and electron (e-) (positronium Ps) can be considered as a kind of hydrogen-like atom and the simplest free radical, which has a positron instead of a heavy nucleus. Annihilation g-radiation is in fact a 
label
of this short-lived atom. Therefore, positronium chemistry is radiochemistry of the lightest short-lived labeled atom. Application of positronium chemistry to various chemical problems is essentially dependent on our knowledge of analogies and differences in the formation and chemical conversion of Ps, a atomic hydrogen, and other free radicals. In this review, experimental results of the authors and some other publications are briefly analyzed from this point of view.
Abstract
Although the estimation of 14C radioactivity is very important from a radiation safety viewpoint at high-intensity and high-energy accelerator facilities, it is very difficult, since there is little information concerning the production cross sections by high-energy nuclear reactions. In this work, the 14C production cross section was measured for the nuclear spallation reaction of aluminum with 12-GeV protons. The chemical separation method of 14C was also studied.
