نتایج جستجو برای: neutron activation
تعداد نتایج: 471710 فیلتر نتایج به سال:
Background: In addition to gas pollutants, many chemicals and air pollutants are in the form of particulate matter. Particulate matter consists of a complex mixture of variable sized particles and physicochemical composition. These particles mainly contain minerals including Fe, Al, Ca, K, Cu, Ti, Mn, Ni, V and their size, chemical composition and concentration are important to assess ...
We report the preparation of neutron-activated xenon for the calibration of liquid xenon (LXe) detectors. Gamma rays from the decay of xenon metastable states, produced by fast neutron activation, were detected and their activities measured in a LXe scintillation detector. Following a five-day activation of natural xenon gas with a Cf (4× 10 n/s) source, the activities of two gamma ray lines at...
A method is described for measuring the concentration of calcium in arterial tissue by neutron activation analysis. The principal advantage is that the method is nondestructive and is ideal for analytical situations in which multiple biochemical measurements are required on a few-milligram sample. Application of the method is illustrated here by a study of aortic calcium metabolism in pigeons a...
Infrared laser probe Ar/Ar geochronology, instrumental neutron activation analysis (INAA) and analytical electron microscopy have been performed on four 0.5 1.0 0.3 cm polished rock tiles of Apollo 16 and 17 granulitic breccias (60035, 77017, 78155, and 79215). Pyroxene thermometry indicates that these samples were re-equilibrated and underwent peak metamorphic sub-solidus recrystallization at ...
Measurements of partial-body calcium by in vivo neutron activation analysis have been carried out on normal and osteoporotic subjects. Based on measurements on 16 normal subjects (volunteers less than 55 years of age), a calcium index has been established that takes into account variation in skeletal frame size. On the basis of this index, all osteoporotic patients have bone mineral content les...
Determination of the more common light elements such as nitrogen and chlorine at trace levels is difficult because of their high abundance on sample surfaces, in materials used to build analysis instruments, and in the residual gas of the instrument vacuum. We present here a new approach to analysis of these elements: accelerator mass spectrometry (AMS) combined with neutron activation. The pro...
A triple stable-isotope method was used to estimate simultaneously selenium absorption from poultry meat intrinsically labelled with 74Se and from an extrinsic tracer of 76SeO3(2-) in four young adult men. The subjects received an experimental diet based on chicken meat as the source of protein. Two diet periods, lasting from 5 to 10 d, depending on the frequency of stool output for each subjec...
The assumption that the shape of the epithermal neutron spectrum can be described, in any research reactor, by the 1/E1+α function is a fundamental starting point of the k0 standardization. This assumption may be questioned from a reactor physics viewpoint. The type of moderator, the existence of neutron reflectors, the additional production of (γ, n) neutrons and resonance capture by construct...
Despite the role of iodine for proper development of the brain and the functions of the element, the accurate data on its concentration in brain tissue are largely lacking, the main reason being analytical difficulties associated with determination of the element especially at low levels. In this work, samples from human brain regions from Hungarian patients were analyzed using epithermal and r...
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