共查询到20条相似文献,搜索用时 15 毫秒
1.
F. Girardi E. Marafante R. Pietra E. Sabbioni A. Marchesini 《Journal of Radioanalytical and Nuclear Chemistry》1977,37(1):427-440
Some typical applications of long-term/low-level exposure (LLE) is presented including in vivo LLE study on rats and in vitro
experiments on some metal binding components as well as on cadimium binding protein. 相似文献
2.
B. Smodiš A. Trkov R. Jaćimović 《Journal of Radioanalytical and Nuclear Chemistry》2003,257(3):481-487
Department of Environmental Sciences, Joef Stefan Institute 相似文献
3.
C. B. Zamboni L. C. Oliveira L. Dalaqua Jr J. Mesa 《Journal of Radioanalytical and Nuclear Chemistry》2006,269(2):331-334
Summary Neutron activation analysis technique, using Au as flux monitor, was applied to determine element concentrations of Ca, K,
Na, Mg, Mn and Sr in certified reference material (NIST 1400 Bone Ash). The results were compared with those using comparative
INAA and they were compatible. The same results were obtained using the recommended k0 factors, in order to obtain the activation cross section as input in concentration for the same reference material. Some
applications in the health area aiming clinical evaluation in bone samples of medium and small-sized animals were performed
and the viability of using this methodology was discussed. 相似文献
4.
D. D. Burgess 《Journal of Radioanalytical and Nuclear Chemistry》1988,123(2):377-386
The application of target factor analysis to the analysis of gamma-ray spectra collected for activation analysis is proposed. Satisfactory analysis of a trial set of samples was carried out using measured spectra as targets. Single-isotope spectra were obtained from mixture spectra by free-floating and performed satisfactorily as target spectra. The factor analysis method requires less resolution than peak-based methods. 相似文献
5.
D. C. Glasgow 《Journal of Radioanalytical and Nuclear Chemistry》2008,276(1):207-211
Delayed neutron activation analysis (DNAA) presents a fast, accurate, and reliable method for quantification of fissile material.
The method has relatively few sources of error and may be accomplished nondestructively. The need for a fast, accurate screening
of materials stems from the necessity to protect cleanroom facilities from widely varying fissile quantities in samples and
from desired gains in efficiency of mass spectrometric analysis by assisting in spike level selection and by removing from
the sample set those materials that are not of interest. During the last several years, many different materials have been
screened or analyzed in support of international safeguards, internal process control for actinide separations, and in uranium
contamination assessments. Swipes from a variety of sources have been analyzed, either before or after dissolution, and comparison
of the DNAA results to mass spectrometry results is generally favorable. A facility characterization of the High Flux Isotope
Reactor was performed using filter paper swipes to demonstrate the utility of the DNAA technique. 相似文献
6.
Zolfaghari Mona Masoudi S. Farhad Rahmani Faezeh 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(3):1477-1483
Journal of Radioanalytical and Nuclear Chemistry - A 20 MeV electron Linac based neutron beam has been shaped for neutron activation analysis (NAA) technique. A beam shaping assembly (BSA)... 相似文献
7.
The inherent advantage of anti-coincidence counting of low-level radioactivity is defined in terms of changes in the limits of decision, detection and determination. It appears that the advantage factor can be expressed in the experimentally observed reductions of peak area, compton continuum and natural background. For an array equipped with a sample changer the advantage factor for interference by the compton continuum is4, while that for interference by the natural background amounts to 3. By sacrificing the sample changer and closing its gap with a Nal-plug, additional factors of 1.5 and 2 can be obtained for compton and natural background respectively. 相似文献
8.
S. Landsberger A. Simsons J. R. Kramer J. J. Drake S. Vermette B. Shuter P. Ihssen 《Journal of Radioanalytical and Nuclear Chemistry》1987,110(2):333-343
Instrumental neutron activation analysis has been successfully employed in three distrinct acid precipitation studies. These include the determination of ten (Al, Br, Ca, Cl, Cu, I, Mg, Mn, Na and V) elements in urban rainfall, elevated aluminum concentrations in acidified lakes and major ions (Ca, Cl, K, Mg and Na) in small-mouth bass kept in controlled pH environments. Quality control was assured by analyzing two certified standard reference materials prepared by the National Bureau of Standards (NBS 1643a) and National Research Council of Canada (hepatopancreas TORT-1 marine biological tissue). 相似文献
9.
A review on the uses of neutron activation techniques for on-stream analysis. 相似文献
10.
Rita Cornelis 《Trends in analytical chemistry : TRAC》1985,4(9):237-241
Over the past three decades, more and more interest has been focused on trace eleemnts in biological materials. This increasing interest has gone hand in hand with the continuous improvement of analytical techniques. Neutron activation analysis has proven to be a most suitable method for the quantitative determination of a wide variety of trace (0.01–100 μg g?1) and ultratrace (<0.01 μg g?1) elements in biological materials. This technique has even played a preponderant role in this field. 相似文献
11.
N. N. Papadopoulos N. F. Tsagas 《Journal of Radioanalytical and Nuclear Chemistry》1993,167(1):103-110
An advanced neutron activation technique has been developed for the accurate analysis of elemental and isotopic fissile material required in nuclear safeguards, nuclear material standardization and other applications. It is based on reactor neutron flux spectrum differentiation by cadmium screening and multistandard calibration, including the solution of a second order equation system or of computerized calibration curve fitting, taking into account the thermal neutron flux depression. Some discrepancies at high enrichments have still to be eliminated in order to achieve the required measurement accuracy. 相似文献
12.
I. H. Degenaar M. Blaauw J. J. M. de Goeij 《Journal of Radioanalytical and Nuclear Chemistry》2003,257(3):467-470
When a sample is analysed with neutron activation analysis (NAA) neutron self-shielding and gamma self-absorption affect the accuracy. Both effects become even more important when the mass of a sample analysed is changed from small (say, 1 g) to large (say 30 kg). Therefore, corrections have to be carried out. In this article only the correction method for neutron self-shielding is considered for a thermal neutron beam irradiating large homogeneous samples for prompt-gamma NAA (PGNAA). The correction method depends on the macroscopic scattering and absorption cross sections of the sample. To avoid doing experiments with samples with different macroscopic scattering and absorption cross sections, the Monte Carlo model MCNP is applied in the development of the correction method. The computational development of the method to determine these cross sections through flux monitoring outside the sample is described. 相似文献
13.
Z. B. Alfassi 《Journal of Radioanalytical and Nuclear Chemistry》1985,90(1):151-165
Different modes of epithermal neutron activation analysis are described. The principles and examples are given for each. 相似文献
14.
S. P. Kapitsa V. N. Melekhin V. N. Samosyuk Yu. M. Tsipenyuk 《Journal of Radioanalytical and Nuclear Chemistry》1973,16(1):297-305
Based on studies of variable multiplicity electron acceleration, the power-current microtron, a cyclic electron accelerator
up to energies of 30–35 MeV has been developed at the Institute on Physical Problems of the Academy of Sciences of the USSR.
The 1–1.5 kW electron beam of the microtron is comparable to the power output of modern linear accelerators operating at similar
energies. At the same time, the microtron has a number of significant advantages, due to the simplicity of design of both
accelerator and ultrahigh-frequency tract, the high efficiency of ultrahigh-frequency power utilization, good operating characteristics,
strictly monochromatic electron beams (variations not exceeding ±50 keV at 30 MeV) and the possibility of continuously changing
particle energy as required by the given experimental task. 相似文献
15.
A very convenient method for yield determination in NAA is the use of isotopic radiotracers. But for the majority of elements determinable by NAA no suitable isotopic radiotracers exist. For some of these elements the radioreagent methodoffers afvourable opportunity to use also non-isotopic radiotracers. An activation analytical copper determination method is described using a radioactively labelled reagent for correction of separation losses. Results of copper determinations in 8 international standard reference materials are given. 相似文献
16.
S. A. Lis Ph. K. Hopke J. L. Fasching 《Journal of Radioanalytical and Nuclear Chemistry》1975,24(1):125-251
In the past several years, a number of gamma-ray tables have been published. All of the tables limit themselves to those nuclides formed in (n, γ) reactions or at most to a few of the more prominent (n, 2n) products. A number of investigators are developing activation analysis methods using fast neutrons or photons. These investigations have been hampered by the lack of tables of gamma-rays of those nuclides that can be formed by (n, 2n), (n, p), (n, α), (n, n′) and (n, d) reactions. Since (γ, n) yields the same product as (n, 2n) the table would also be useful to photon activation studies. The authors have compiled such a table. Section II: list of the gamma-rays for all isotopes in order of increasing energy will be published in the J. Radioanal. Chem., 25 (1975) No. 2. 相似文献
17.
H. H. Chen-Mayer V. A. Sharov D. F. R. Mildner R. G. Downing R. L. Paul R. M. Lindstrom C. J. Zeissler Q. F. Xiao 《Journal of Radioanalytical and Nuclear Chemistry》1997,215(1):141-145
A neutron lens has been constructed to focus cold neutrons from the exit of a58Ni neutron guide, which delivers a beam to the Prompt-Gamma Activation Analysis (PGAA) station at the NIST Cold Neutron Research Facility. The lens compresses a neutron beam of cross section 50 mm× 45 mm onto a focal spot of diameter 0.53 mm (fwhm) wich an average gain of 80 in neutron current density. PGAA measurements have been performed to demonstrate the enhanced sensitivity and detection limits for various elements and the spatial resolution in one transverse dimension. For the two test particles (a gadolinium glass bead and cadmium metal of sizes less than 0.5 mm), the gain in the -count rate with the lens is a factor of 60, and the detection limit is improved by a factor of 20. The system can be used for two-dimensional mapping of samples on a sub-millimeter scale to complement other analytical techniques such as neutron depth profiling (NDP). 相似文献
18.
M. Attas J. D. Chen E. A. Hildebrandt 《Journal of Radioanalytical and Nuclear Chemistry》1987,109(1):55-68
A fully automated neutron activation analysis (NAA) facility has been constructed at the Whiteshell Nuclear Research Establishment. This high-capacity facility has been designed for use with a wide variety of neutron sources, including Canada's SLOWPOKE II and MAPLE research reactors. Its pneumatic transfer system is driven by a Square-D Model 500 programmable controller, linked in turn to a Nuclear Data ND6700 computer/spectrometer. Custom software for data entry and system control has been combined with Nuclear Data software for gamma-spectrum acquisition and processing to create a flexible, easy-to-use facility for NAA. Its design and performance are discussed. 相似文献
19.
A new type of extractant, sym-dibenzo-16-crown-5-oxyhydroxamic acid (HL) is introduced. The extractions of UO22+, Na+, K+, Sr2+, Ba2+ and Br- were studied with HL in chloroform. The results obtained show that UO22+ can be quantitatively extracted at pH values above 5, whereas the extractions of K+, Na+, Sr2+, Ba2+ and Br- are negligible in the pH range of 2 - 7. The dependence of the distribution ratio of U(VI) on both the concentration of the HL and pH are linear, and they have the same slope of 2. This suggests that U(VI) appears to form a 1:2 complex with ligand. Uranium(VI) can be selectively separated and concentrated from interfering elements such as Na, K, Sr and Br by solvent extraction with HL under specific conditions. The recovery of uranium is nearly 100% and the radionudear purity of uranium is greater than 99.99%. Therefore, neutron activation analysis has greatly improved the sensitivity and accuracy for the detection of trace uranium from seawater. 相似文献
20.
Peter Bode 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(2):275-280
Neutron activation laboratories worldwide are at a turning point at which new staff has to be found for the retiring pioneers
from the 1960s–1970s. A scientific career in a well-understood technique, often characterized as ‘mature’ may only be attractive
to young scientists if still challenges for further improvement and inspiring new applications can be offered. The strengths
and weaknesses of neutron activation analysis (NAA) are revisited to identify opportunities for innovation. Position-sensitive
detection of elements in large samples, Monte Carlo calculations replacing the use of standards, use of scintillator detectors
and new deconvolution techniques for increasing the sensitivity are examples of challenging new roads in NAA. Material science
provides challenges for the application of NAA in both bulk samples, ultrathin layers and ultrapure materials. 相似文献