Search Results
Abstract
We report on chronopotentiometric investigations of the UFe, UCu and UNi alloys. The experimental procedure is based on the control of the pO2– of the liquid melt and that allows to avoid undesirable chemical side-reactions. The capability of the method to prove the existence of two different metallic phases either of similar compositions or of non-stoichiometric composition is discussed.
Abstract
Using the facilities of the Triga Mark III reactor at the NNRI, Mexico and the HAV-1 multipurpose monitor, the reactor power dependency for thek
0-standardization essential neutron flux parameters as: epithermal shape factor (
), thermal to epithermal ratio (f) and neutron temperature (T
n
) were experimentally obtained. Evaluation of the obtained dependencies shows that it is unnecessary to analyze the possible introduction of correction factors in thek
0-INAA experimental results. A single experimental procedure to determine throughf is suggested.
Abstract
A method for Cr determination in biological samples based on proton nuclear activation is presented. The activation was induced by a 13.8 MeV proton beam of the AVF Cyclotron of Milan University via a (p, n) reaction on the nuclei of the target. For the quantitative determination Cd has been chosen as reference element. The method has been applied to Cr determination in human serum samples. The experimental procedure is described and results are presented and discussed.
Abstract
Assessment of environmental risks of granular wastes, immobilised in monolithic bodies implies at least three independent, preferably standardised, tests: Weight variations during drying and wetting; leaching with water or dilute acid and determination of the available fraction of the micro-constituent involved. Their accuracy, precision and minimal turn-over time depend on the dimensions of the test specimen and the experimental procedure. They are considered here in relation to the inevitable underlying assumptions and the practical limitation of the turn-over time. Two standard geometries of test aliquots are considered in detail. The use of radioanalysis in the determination of some of the characterising parameters is summarised.
Abstract
With the purpose of providing a quick method directly suitable for oxygen determinations in various metals, the factors influencing accuracy and sensitivity of the16O(n, p)16N reaction have been investigated. The interferences caused by B, F and N have been studied. Pile-up effects and surface contaminations were lowered and matrix effects calculated. The background noise was kept at a minimum. The critical level of oxygen detection corresponds to 3 μg. The experimental procedure is useful down to the sub-μg/g level for oxygen determinations in metals and alloys.
Abstract
The advantages and drawbacks of using instrumental neutron activation analysis (INAA) and inductively coupled plasma mass spectrometry (ICP-MS) for soil, sediment, plant and water pollution studies are discussed. The experimental procedures used for each method and for each type of sample matrix are described. They were tested on several certified reference materials. The results obtained on these materials showed good agreement for many elements for which the two techniques are suited, and they were complementary for the other elements which are also of environmental interest. An element-by-element assessment is presented to indicate the precautions to be taken and the most convenient technique for each of them.
Abstract
Fast neutron activation analysis (FNAA) has proven to be a useful technique for the estimation of non-metallic inclusions in metals, and is currently being used in industry, especially for the determination of oxygen in magnesium alloys. However, high levels of radioactivity induced in large metallic samples by irradiation in a neutron field give rise to matrix interferences which are significant at low oxygen concentrations. These interferences are due to coincidental summations that fall into the energy window used for quantitation of oxygen. This report explains technical details of newly developed experimental procedures and alterations of existing software which correct for the errors, thereby enhancing the potential for use of the method.
Abstract
Composite SiO2—iron oxide materials were prepared by three experimental procedures. In the first case, the iron oxides were precipitated during a sol-gel process. In the second case, a SiO2 matrix was initially obtained, and the iron oxides were formed by thermal treatment after impregnation of a soluble Fe2+ salt in the previously processed matrix. In the third method, ferrite powders, prepared by wet chemical method, were embedded into a SiO2 based sol-gel matrix. Materials with convenient porosity and nano-sized iron oxide content could be prepared using the mentioned methods. The prepared composite has been tested for arsenic(V) removal.
Abstract
An intercomparison on absolute activity measurements of125I sources by the sumpeak method was carried out in 1993 between the Primary Standard Laboratories for Ionizing Radiations of Italy (ENEA) and Albania (INP). The sources were prepared by ENEA starting from a125I solution. The sources were measured at ENEA and successively at INP. The results were in good agreement, the deviation of the INP results from the ENEA results being about –0.5% with an overall uncertainty of both results about 0.3% (1
). This paper describes the instrumentation and the experimental procedures used in this comparison by the two Institutes.
Abstract
Proton Induced X-ray Emission (PIXE) method is used for the determination of elemental concentrations in cancellous bone of human femoral head from five autopsies and seven patients with femoral neck broken. The specimen preparation and experimental procedure are described in detail. Using the t test, the results show that the concentrations of P, Ca, Fe, Cu, Sr in control group are higher than those in patient group, but the concentrations of S, K, Zn, Mn are not significantly different. The physiological functions of metallic elements in human bone are also discussed.
