共查询到20条相似文献,搜索用时 31 毫秒
1.
D. A. Haas S. R. Biegalski K. M. Foltz Biegalski 《Journal of Radioanalytical and Nuclear Chemistry》2008,277(3):561-565
In support of the Comprehensive Nuclear-Test-Ban Treaty (CTBT), improvements have been made to the model of the Automated
Radioxenon Sampler/Analyzer (ARSA) β-γ coincidence detector for radioxenon monitoring. MCNPX is used to simulate the detector
response for all the electrons and photons emitted from 131mXe, 133Xe, 133mXe, 135Xe, and 137Cs signals. A MatLab code was written to incorporate the MCNPX results in the calculation of β-γ coincidence spectra. These
will aid in the development of the Spectral Deconvolution Analysis Tool (SDAT)1 and to calibrate β-γ coincidence systems. The models developed for this work include improvements over previous models in
their ability to address Compton scattering in the β-cell, and the β-distribution offset in the 31 keV γ-ray region for 133Xe. 相似文献
2.
A. Ortiz S. Ramos-Bernal A. Negrón-Mendoza T. Martínez G. Sanchez-Mejorada 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(3):573-575
The thermoluminescense (TL) behavior of solid solutions of cadmium and manganese doped single crystals under γ-irradiation
is reported. Various compositions of single crystals of NaCl doped with Cd2+ and Mn2+ have been irradiated with ionizing radiation. The increase in the glow curve was followed as a function of the F-centers
produced by the dose. The analysis shows the potential use of these materials as dosimeters. 相似文献
3.
T. Belgya 《Journal of Radioanalytical and Nuclear Chemistry》2008,276(3):609-614
The 14N(n,γ)15N reaction is a primary γ-ray source for high energy calibration of detectors. The relative γ-ray-intensities of 15N and the relative γ-ray detection efficiency function have been simultaneously determined up to 10 MeV from γ-peak areas
alone. Absolute γ-ray-intensities were obtained with proper renormalization to known absolute intensity. The influence of
these new intensity values are assessed for use in PGAA. Any consistently used set of calibration intensities applied in the
creation of library values and for analysis do not influence the concentrations. Contrary to this, quantities based on sums
of γ-ray cross sections may provide different answers with the new 15N intensities and they give means to validate them. 相似文献
4.
Separation and purification of <Superscript>249</Superscript>Cf and <Superscript>245</Superscript>Cm
There is a need to provide radioactivity standards of the higher actinides in support of both decommissioning and remediation
activities as well as routine environmental analysis. In the case 249Cf, this will provide a useful calibration nuclide for both α-and γ-spectrometry as well as improving knowledge of the decay
scheme for this nuclide. There is anecdotal evidence to suggest that the chemical yield of americium and curium may differ
in radiochemical analysis. Thus, a chemical yield tracer of 245Cm may help to resolve this issue and will be suitable for both, suitable for use as a chemical yield tracer for both α-particle
spectrometry and mass spectrometry. An aged source of 249Cf was used as the source material for the separation of these two nuclides by cation-exchange, using 2-hydroxy-2-methyl-propanoic
acid at controlled pH as an eluant, 249Cf being eluted before the 245Cm daughter. The purity of both nuclides was measured by γ-ray spectrometry. 相似文献
5.
Adsorption of long-lived 125Sb radioisotope (T
1/2 = 2.75 y) on alumina (Al2O3) and titania (TiO2) has been studied at different pH. Both the oxides have good adsorption capability for the 125Sb radioisotopes but the TiO2 is much superior. Adsorption kinetics of 125Sb radioisotopes on TiO2 surface and desorption of 125Sb radioisotopes from TiO2 surface in acidic and alkaline media have also been studied. The 125Sb-TiO2 phase has been subjected to γ-irradiation and found to be radiation stable against antimony release. 相似文献
6.
Xinfeng You Shengdong Zhang Zhihong Yang Youqian Ding Anzhi Cui 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(1):267-272
101Tc is a very important nuclide as fuel burn up monitor, and its half-life value has been measured many times, however, they
were so different from each other. In this work, 101Tc liquid samples were prepared by irradiating analytical pure (NH4)6Mo7O24·4H2O solution in Miniature Neutron Source Reactor (MNSR) of China. A rapid procedure which takes only 5 min was developed to
separate 101Tc samples. The final samples were analyzed by γ-ray spectrum using high purity Germanium (HPGe) multi-channel analysis system.
The results showed that there were no peaks of other nuclides except 101Tc. The half-life of 101Tc was accurately measured with HPGe γ-detector following 306.8 keV γ-ray for about 140 min, and three methods R-value method,
iterative method and translation method were adopted to process the data. Finally, a more precise and accurate value 14.02 ± 0.01 min
was given and compared with former measured data. 相似文献
7.
S. R. F. Biegalski K. M. Foltz Biegalski D. A. Haas 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(3):715-719
The Spectral Deconvolution Analysis Tool (SDAT) software was developed at The University of Texas at Austin. SDAT utilizes
a standard spectrum technique for the analysis of β–γ coincidence spectra. Testing was performed on the software to compare
the standard spectrum analysis technique with a region of interest (ROI) analysis technique. Experimentally produced standard
spectra and sample data were produced at the Nuclear Engineering Teaching Laboratory (NETL) TRIGA reactor. The results of
the testing showed that the standard spectrum technique had lower errors than the ROI analysis technique for samples with
low counting statistics. In contrast, the ROI analysis technique outperformed the standard spectrum technique in high counting
statistics samples. It was also shown that the standard spectrum technique benefitted from a compression of the number of
channels within the spectra. 相似文献
8.
S. Musić G. Štefanić N. Vdović A. Sekulić 《Journal of Thermal Analysis and Calorimetry》2000,59(3):837-846
Zirconium hydroxide particles produced by rapid precipitation at pH 10.4, 7 or 2 were subjected toγ-irradiation up to a final
dose of 20 MGy. The effects of the γ-irradiation were examined by X-ray powder diffraction, laser Raman spectroscopy, differential
scanning calorimetry and microelectrophoretic measurements. It was found that γ-irradiation had no influence on the behaviour
of zirconium hydroxide during calcination and subsequent cooling. The results of microelectrophoretic measurements showed
that γ-irradiation influences the surface properties of zirconium hydroxide as a function of the precipitation pH. Zirconium
hydroxide precipitated at pH 2 proved to be the most susceptible to γ-irradiation, while the sameγ-irradiation had very little
(if any) effect on the surface properties of zirconium hydroxide precipitated at pH 10.5. After γ-irradiation, the electrophoretic
mobility of zirconium hydroxide precipitated at pH 2 was increased at both low and high pH, thereby indicating an increase
in its adsorption capacity. The analogy observed between the pH-dependence of the effects of γ-irradiation on the electrokinetic
behaviour of zirconium hydroxide and the influence of ball-milling on the thermal behaviour of zirconium hydroxide [8] suggested
that the susceptibility of amorphous zirconium hydroxide increases with decrease of the precipitation pH.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
A. Amekudzie O. Adukpo J. Annkah A. Faanu G. Emi-Reynolds 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(3):795-800
As part of monitoring the exposure of the Ghanaian public to natural radioactivity, radioactivity concentrations in titanium
enamel frits use for coating, spraying and decorating steel bowls were investigated. Samples collected from Ghana Utensil
Manufacturing Company in Ghana were analyzed using γ-ray spectrometry with a high purity germanium detector. The samples were
found to contain an average absorbed dose rate of 509.38 nGy h−1, while an average annual effective dose was calculated to be 2.50 mSv. 相似文献
10.
Yong Yi Peng Zhou Guangshan Liu 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(1):157-162
The atmospheric deposition fluxes of 7Be, 210Pb and 210Po at Xiamen were measured. The samples were collected from March 2004 to April 2005 and the sampling period was one month.
The 7Be and 210Pb activity were measured using HPGe γ-spectrometer after concentration using Fe(OH)3 co-precipitation method. The 210Po was counted with an α-spectrometer after the sample was digested and spontaneous plated onto a silver planchet. At Xiamen,
the atmospheric deposition fluxes of 7Be varied between 0.11 and 2.93 Bq·m−2·d−1 and the average was 1.64 Bq·m−2·d−1; 210Pb fluxes varied between 0.04 and 0.85 Bq·m−2·d−1, and the average was 0.51 Bq·m−2·d−1; 210Po fluxes varied between 0.002 and 0.133 Bq·m−2·d−1, and the average was 0.061 Bq·m−2·d−1. There were positive correlations between the deposition fluxes of 7Be, 210Pb or 210Po and the amount of precipitation. The residence time of aerosols varied between 6.0 and 54.0 days with a mean of 27.1 days,
which were calculated by 210Po/210Pb fluxes ratios. 相似文献
11.
Rubel Chakravarty Meera Venkatesh Ashutosh Dash 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(1):45-51
A novel electrochemical process to avail clinical grade 99mTc from (n,γ)99Mo has been demonstrated. The electrochemical parameters were optimized to maximize the 99mTc yield with minimal 99Mo contamination. 99Mo/99mTc generators containing up to 29.6 GBq (800 mCi) 99Mo were developed and their performance were extensively evaluated for 10 days without changing the operating conditions.
Very high radioactive concentration of 99mTcO4
− of acceptable quality, commensurate with hospital radiopharmacy requirements could be availed from the system with >90% yield.
The compatibility of the product for the formulation of 99mTc labeled radiopharmaceuticals such as 99mTc-DMSA and 99mTc-EC was found to be satisfactory in terms of high labeling yields. The proposed route represents an important step for enhancing
the scope of accessing clinical grade 99mTc from low specific activity (n, γ)99Mo. 相似文献
12.
The analysis of 226Ra in natural waters can be tedious and time-consuming. For the determination and differentiation of activities of 226Ra and 222Rn in drinking water by γ-ray spectrometry a simple and fast method is presented. Activities of 226Ra > 0.5 Bq L−1 can be determined according to stabilization of the sample without further procedures. For a more sensitive detection sample
volumes of up to 5 litres are applicable by a rapid precipitation procedure without large expenditure. Further laborious enrichment
methods are not necessary. Thus, detection limits of 0.1 Bq L−1 can be obtained when using sample volumes of 5 litres. Therefore the method is suitable for the monitoring of radioactivity
in drinking water samples in accordance with the legal guidance of the European Union. 相似文献
13.
Robert Kandlbinder Robert Schupfner Otto S. Wolfbeis 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(1):69-73
The determination of 228Ra by means of γ-spectrometry, in material containing significant quantities of 40K and Ca2+ such as bone ash results in increased values of counting uncertainty and lower limit of detection (LLD) because of a significant
contribution from the Compton continuum of 40K. However, 40K is widely removed from bone ash if 228Ra is coprecipitated with barium sulfate. As a result, the counting uncertainty and LLD are significantly reduced. A method
is presented for determination of very low activity concentrations of 228Ra. Impurities introduced by precipitation are negligible when applying high resolution γ-spectrometry. 相似文献
14.
S. Anilkumar A. K. Deepa K. Narayani A. K. Rekha P. V. Achuthan G. Krishnamachari D. N. Sharma 《Journal of Radioanalytical and Nuclear Chemistry》2007,274(1):161-166
The migration of 237Np in an undisturbed Chinese loess column was investigated by direct γ-ray method. The column was taken from a field test site and installed in a laboratory simulation hall. Radionuclide 237Np in the form of neptunium nitrate, mixed with quartz, was introduced into the column and covered with loess. Artificial
rainfall was applied to the column for about 3 years and, the counting rates of 237Np in the column from 56 to 616 days at different vertical positions were detected with a γ-ray detection system. Based on the counting rates of 237Np in the simulation column at different vertical positions and the distance from the source layer, the relationship of the
mass center of 237Np in the column at different experimental periods to the experimental time was established, C
m = 0.36 log(t)-2.75. Here C
m is the mass center of 237Np in the column, cm, and t is the experimental time in days. Based on this relationship, the mass center of 237Np for the 1,073-day experiment was predicted and compared to that obtained with the final destructive method. The good agreement
between the prediction and the experimental values indicates that the direct γ-ray method could be used to predict the migration of strongly adsorbed radionuclides such as 237Np in environmental media with the help of laboratory simulation columns. 相似文献
15.
M. Reková F. Budský V. Miler Z. Málek V. Jedináková-Křížová 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(3):853-859
The aim of the study of labeling of ligand–antibody conjugates was to find optimal conditions of preparing of these conjugates
and appropriate radioactivity of selected nuclide for applications in nuclear medicine. Conjugation of the γ-immunoglobulin
G (human or bovine IgG, polyclonal antibodies) and bifunctional chelating agent, diethylenetriaminepentaacetic acid dianhydride
(cDTPAA), was carried out. Various values of the cDTPAA/antibody ratio, the weight concentration of polyclonal or monoclonal
antibodies (MEM-97) and buffers were used. Further, the labeling conditions of the DTPA–IgG conjugate by radionuclides 90Y and 177Lu were optimized, and the labeling yield and the conjugation ratio of prepared radionuclide–DTPA–IgG conjugates was determined.
Optimal incubation time of the immunoglobulin conjugation was obtained at 30 min from mixing of individual components. The
labeling yield of radionuclide–DTPA–antibody conjugate higher than 95% was achieved. Higher values of conjugation ratio of
radionuclide–DTPA–antibody conjugate were achieved in 0.1 mol L−1 carbonate buffer, pH 8.5, and the 0.1 mol L−1 carbonate buffer is suitable for studied conjugation systems. This study showed that the labeling yield as well as the conjugation
ratio of tested systems depend on the amount of antibody substance, bifunctional chelating agent/antibody molar ratio and
pH value of the buffer used. 相似文献
16.
Youjiu Zhang Yujie Xu Ran Zhu Mingjiang Hu Jianxiang Li Yuejin Chen Daojin Wang Wo Fan 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(1):3-8
This study examined the tissues distribution and pharmacokinetics of rhTNT-IL2, a fusion protein, in rats and macaques after
iv. injection. The rhTNT-IL2 was labeled with 125I. The 125I-rhTNT-IL2 was administered into rats and macaques at a dose of 250 μg·kg−1 and 125 μg·kg−1, respectively. Upon administration, rhTNT-IL2 declined in tri-exponentially with the half-lives of 1.78 h (T
1/2α), 25.06 h (T
1/2β), 114.19 h (T
1/2γ) for rats and 1.87 h (T
1/2α), 9.82 h (T
1/2β), 43.17 h (T
1/2γ) for macaques. The fraction of 125I-rhTNT-IL2 excreted in feces was low (about 1%), while the majority of 125I-rhTN-IL2 was excreted in urine. The tissue distributions showed that the liver, spleen and heart were major organs for deposition
of the fusion protein in rats and macaques in 48-hour post-injection, and the fusion protein could not penetrate through blood
brain barrier. 相似文献
17.
Y. B. Xu S. D. Zhang H. J. Ding X. T. Lu W. F. Yang S. G. Yuan Y. H. Xiao Y. N. Niu 《Journal of Radioanalytical and Nuclear Chemistry》2007,272(2):227-230
The neutron-rich target-like isotope 236Th has been produced in the 238U-2p multinucleon transfer reaction between a 60 MeV/u 18O beam and natural 238U targets. The activities of thorium were determined after radiochemical separation of Th from the mixture of uranium and
reaction products. The 236Th isotope was identified by the characteristic γ-rays of 642.2, 687.6 and 229.6 keV. The production cross section of 236Th was determined to be 250±50 μb. 相似文献
18.
The mono- and bisligands complexes formed by rare earth cation (Sc, Y) with pentazolato anion or cyclo-P5− anion, the all-nitrogen counterparts of metallocenes or the all-phosphorus counterparts of metallocenes, have been studied
at hybrid basis sets level with the DFT method. The geometric parameters, binding energy and the charge distributions of these
complexes were characterized. And their stable orders were obtained. Monoligand complexes incline to become bisligands complexes
due to their destabilization. The charge transferring between ligand and metallic cation has affinity with the stability of
complex. The possibility of forming stable [M(η
5-E5)2] (M = Sc, Y, E = N, P) complexes is predicted and they are viable synthetic targets theoretically, especially Sc(η
5-N5)2. 相似文献
19.
T. Lönnroth K. -M. Källman J -O. Lill D. Agren 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(1):163-165
We report the measurements of 7Be activity in nine vegetable species through the detection of its 477.6 keV γ-ray of 7Li. The plants were grown 10 km south of the city of Turku in south-west Finland, located at approximately about 23E, 62N.
The results show that nettle, salad and cucumber have activities that exceed the detection limit. 相似文献
20.
A. I. Kazakov Yu. I. Rubtsov E. P. Kirpichev G. B. Manelis 《Russian Chemical Bulletin》1998,47(6):1084-1088
The influence of preliminary γ-irradiation and γ-irradiation during hte oxidation process on the kinetics of heat release
in the systemsn-decane—aqueous solution of HNO3 and a solution of tributyl phosphate in a kerosene—aqueous solution of HNO3 was studied. The preliminary γ-irradiation of the system at 43°C increases the initial rate of the process (k
1). The increase is proportional to the irradiation dose at doses up to 150kGy, then the increase ink
1 is retarded, and the further course of the process becomes practically independent of the irradiation dose. The effect of
γ-irradiation during the oxidation depends on the temperature of the system: at temperatures lower than 80 °C, γ-irradiation
increases the rate of heat release, whereas at higher temperatures, γ-irradiation decreases the rate of heat release. The
effects observed were explained by the competition of NO2 accumulation due to the radiolysis of nitric acid and processes of the addition of NO2 to unsaturated hydrocarbons produced by the radiolysis of the organic phase.
Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1116–1120, June, 1998. 相似文献