共查询到20条相似文献,搜索用时 562 毫秒
1.
S. K. Aggarwal D. Alamelu P. M. Shah N. N. Mirashi 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(3):771-774
Determination of 241Am/243Am ratios is required for vanous purposes including assay of Am by isotope dilution techniques. Alpha-spectrometry on electrodeposited
sources is a preferred technique for this determination. However, there is an inherent problem of tail contribution which
necessitates the use of suitable algorithms to account for the same. Recently, in the frame of a Coordinated Research Program
(CRP) of the International Atomic Energy Agency (IAEA), WinALPHA software has been developed which is a combination of an
asymmetrical Gaussian for the main part of the peak and a low energy function. Therefore, it was of interest to compare the
use of this algorithm with the routinely used method, in our laboratory, based on geometric progression (G. P.) decrease.
Since, there are no reference materials available commercially for 241Am/243Am ratios, synthetic mixtures covening a wide range (0.3 to 2.0) of 241Am/243Am α-activity ratios were used and un-ignited electrodeposited sources were prepared for α-spectrometry. The α-spectra obtained using PIPS detector, were evaluated using the two algonthms The 241Am/243Am α-activity ratios obtained were also compared with those determined by thermal ionization mass spectrometry (TIMS). An agreement
of about 1% was obtained in the 241Am/243Am ratios determined by the two methods and also by using the two algorithms for α-spectrum evaluation. 相似文献
2.
Sultan Şahin Fatih Külahcı Mahmut Doğru 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(2):313-318
In this study, 90Sr (540 keVβ −), 129I (150 keVβ −) and the gross beta radioactivity concentrations were determined for the samples of tea as the most leading consumed hot
drink in the markets (processed and packaged for sale) in our country. Furthermore, the obtained data were statistically analyzed.
For determination of 129I (150 keVβ−), 90Sr (540 keVβ−) and gross radioactivity concentrations in tea samples, a sensor system consisting of scintillation detector with BP4 probe
sensitive to beta radiation and a radiation meter (ST7) configurable for windows at desired power was used. 相似文献
3.
J. J. LaBrecque P. R. Cordoves M. A. Cordoves K. Perez D. Palacios J. A. Alfonso 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(3):669-674
This work presents the results of 137Cs, 40K, 232Th and 238U concentration (Bq kg−1) values in coastal marine sediments collected from 38 sites along the coastline of the island of Margarita, Venezuela. The
purpose was to determine baseline values for these radionuclides in surface marine sediments and to detect if there were any
anomalously high concentration values. Only three of the 38 sediments analyzed had measurable values above the detection limit
of 0.9 Bq kg−1 for 137Cs and the highest only being 1.4 Bq kg−1. While, the concentration (Bq kg−1) ranges for the primordial radionuclides, 40K, 232Th and 238U were as follows: 12.2–211.7, <1.5–9.8 and <4.4–20.7, respectively. These concentration ranges for the primordial radionuclides
can be considered as baseline values for surface marine sediments for areas that are considered not polluted by man or contaminated
by nature. Finally, the concentration range of 137Cs can also be employed as baseline values, which only seem to have been the result of the atmospheric testing of nuclear
weapons in the past. 相似文献
4.
Xiao-Ying Li Yong Ren Xue-Jiao Chen Da-Yong Qiao Wei-Zheng Yuan 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(1):173-176
The design, fabrication, and testing of a 4H-SiC Schottky betavoltaic nuclear battery based on MEMS fabrication technology
are presented in this paper. It uses a Schottky diode with an active area of 3.14 mm2 to collect the charge from a 4 mCi/cm2
63Ni source. Some of the critical steps in process integration for fabricating silicon carbide-based Schottky diode were addressed.
A prototype of this battery was fabricated and tested under the illumination of the 63Ni source with an activity of 0.12 mCi. An open circuit voltage (V
OC) of 0.27 V and a short circuit current density (J
SC) of 25.57 nA/cm2 are measured. The maximum output power density (P
max) of 4.08 nW/cm2 and power conversion efficiency (η) of 1.01% is obtained. The performance of this battery is expected to be significantly
improved by using larger activity and optimizing the design and processing technology of the battery. By achieving comparable
performance with previously constructed p–n or p–i–n junction energy conversion structures, the Schottky barrier diode proves
to be a feasible approach to achieve practical betavoltaics. 相似文献
5.
Hassan Yousefnia Edalat Radfar Amir Reza Jalilian Ali Bahrami-Samani Simindokht Shirvani-Arani Azim Arbabi Mohammad Ghannadi-Maragheh 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(1):199-209
Rituximab was successively labeled with 177Lu-lutetium chloride. 177Lu chloride was obtained by thermal neutron flux (4 × 1013 n cm−2 s−1) of natural Lu2O3 sample with a specific activity of 2.6–3 GBq/mg. The macrocyclic bifunctional chelating agent, N-succinimidyl-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic
acid (DOTA-NHS) was prepared at 25 °C using DOTA, N-hydroxy succinimide (NHS) in CH2Cl2. DOTA-rituximab was obtained by the addition of 1 mL of a rituximab pharmaceutical solution (5 mg/mL, in phosphate buffer,
pH 7.8) to a glass tube pre-coated with DOTA-NHS (0.01–0.1 mg) at 25 °C with continuous mild stirring for 15 h. Radiolabeling
was performed at 37 °C in 24 h. Radio-thin layer chromatography showed an overall radiochemical purity of >98% at optimized
conditions (specific activity = 444 MBq/mg, labeling efficacy; 82%). The final isotonic 177Lu-DOTA-rituximab complex was checked by gel electrophoresis for structure integrity control. Radio-TLC was performed to ensure
that only one species was present after filtration through a 0.22 μm filter. Preliminary biodistribution studies in normal
rats were carried out to determine complex distribution of the radioimmunoconjugate up to 168 h. The biodistribution data
were in accordance with other antiCD20 radioimmunoconjugates already reported. 相似文献
6.
P. Vesterbacka S. Klemola K. Salahel-Din M. Saman 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(3):441-448
An intercomparison of the methodology (alpha, beta and gamma spectrometry) used for 238U, 235U and 210Pb determination was carried out based on 38 sediment samples. The activity range of the samples varied from 10–700 Bq/kg
for 210Pb, 1–35 Bq/kg for 235U and 10–800 Bq/kg for 238U. Results obtained using the three methods were not statistically different at high activity levels, but agreement between
the results decreased at lower sample activity levels. For 210Pb, the smallest difference was found between alpha and gamma spectrometry. A good correlation between results from alpha
and gamma spectrometry was observed over the whole activity range. In beta spectrometry, the results were slightly higher
than those obtained by alpha or gamma spectrometry due to the impurity of 228Ra. In 238U analysis, good correspondence was observed between 238U determined by gamma and alpha spectrometry, particularly at higher 238U activity concentrations over 100 Bq/kg. In 235U analysis, attention needs to be paid to interference from 226Ra and its reduction. 相似文献
7.
In recent years, there has been a rapid expansion in the use of radio nuclides for therapeutic purposes. Thulium–167 is an
important radionuclide (T
1/2 = 9.25 d) due to it could be used for tumor and bone studies in nuclear medicine. 167Tm complexed with hydroxy ethylene diamine tetra-acetic acid (HEDTA) could be used with the aim of bone imaging. 167Tm emits a prominent γ ray of 208 keV energy and low energy electrons. This study describes calculations on the excitation
functions of 165Ho(α,2n)167Tm, 167Er(p,n)167Tm, natEr(d,xn)167Tm and natEr(p,xn)167Tm reactions by ALICE/ASH (hybrid and GDH models) and TALYS-1.0 codes. In addition, calculated data by codes were compared
to experimental data that earlier were published and TENDL-2010 database. Moreover, optimal thickness of the targets and physical
yield were obtained by SRIM (stopping and range of ions in matter) code for each reaction. According to the results, the 167Er(p,n)167Tm and 165Ho(α,2n)167Tm reactions are suggested as the best method to produce 167Tm owing to minimum impurities. The TALYS-1.0 code, predict the maximum cross-section of about 382 mb at 11 MeV and 849 mb
at 26 MeV for 167Er(p,n)167Tm and 165Ho(α,2n)167Tm reactions, respectively. Finally, deposition of natEr2O3 on Cu substrate was carried out via the sedimentation method. The 516 mg of erbium(III)oxide with 103.2 mg of ethyl cellulose
and 8 mL of acetone were used to prepare a natEr2O3 layer of 11.69 cm2. 167Tm was produced via the natEr(p,n)167Tm nuclear process at 20 μA current and 15 → 7 MeV protons beam (1 h). Yield of about 3.2 MBq 167Tm per μA h were experimentally obtained. 相似文献
8.
Hojjat Nadi Mahdi Sadeghi Milad Enferadi Parvin Sarabadani 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(2):361-365
In the present study, ytterbium-169 was produced via the 169Tm(p, n)169Yb nuclear process at the AMIRS (Cyclone-30, IBA, Belgium) cyclotron, irradiating Tm2O3 with proton particles of 15 MeV primary energy and 20 μA current for 20 min. Deposition of Tm2O3 on Cu substrate was carried out via by the sedimentation method. The 543 mg of thulium(III)oxide with 108 mg of ethyl cellulose
and 8 mL of acetone were used to prepare a Tm2O3 layer of 11.69 cm2. Yields of about 0.643 MBq 169Yb per μAh were experimentally obtained. 169Yb was separated in 80 ± 5% radiochemical yield using liquid–liquid extraction. Solvent extraction of no-carrier-added 169Yb from irradiated thulium(III)oxide target hydrochloric solution was investigated using di-(2-ethylhexyl)phosphoric acid
(HDEHP). 相似文献
9.
Mamdouh S. Masoud Amina A. Soayed Ahmed S. Elkholany 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(3):1123-1130
The reaction of 99mTc of different oxidation states (+7, +4) with 2-thiouracil and 5-nitrobarbituric acid have been studied at different temperatures,
pH and concentrations. The reaction mixtures have been analyzed at different times using thin layer chromatography (TLC) and
a radio detector to show the peaks at the plates. 99mTc is obtained from the Mo generators with oxidation state (+7). The use of SnCl2 as a reducing agent gave 99mTc with oxidation state (+4). It is very difficult to separate the complexes formed from the reactions in very small concentration.
The percentage of 99mTc and its oxidation state involved in the complexes can be determined. The labeling efficiencies (percentage of complex)
in the reaction of 99mTc+7 with 5-nitro-barbituric-acid increases mostly at pH 10. Both oxidation states of 99mTc(+7, +4) can be detected at pH’s 4 and 10, but at pH 4, the reduced form 99mTCO2, is more pronounced. At pH 7 no complexes were detected and most of 99mTc remains as 99mTCO4
−
. By increasing the ligand concentration, the labeling efficiencies of the complex increases. For the reaction of 99mTc of oxidation states (+4, +7) with 2-thiouracil at different temperatures and analytical times it is concluded that several
complexes with different Rf values were observed in equilibrium and most of these complexes were unstable. 相似文献
10.
M. Clara Gonçalves Luis M. Fortes Rui M. Almeida Alessandro Chiasera Andrea Chiappini Maurizio Ferrari Shivakiran Bhaktha 《Journal of Sol-Gel Science and Technology》2010,55(1):52-58
Er3+ photoluminescence (PL) and Yb3+ → Er3+ energy transfer (ET) phenomena in the near infrared (NIR) have been studied in three-dimensional (3-D) inverse opal (IO)
structures synthesized by a colloidal/sol–gel route, starting with the deposition of polystyrene microsphere (235 nm and 460 nm
diameter) direct opal templates by convective self-assembly, followed by infiltration of the interstices with Er3+/Yb3+-doped silica, titania and silica-titania sols and heat-removal of the polymeric template material. The crystalline quality
of the IOs has been optimized through suitable substrate treatments, plus the control of temperature and humidity during deposition
of the templates. The structural and optical properties of the 3-D opal and IO structures have been studied by field emission
scanning electron microscopy and visible-NIR reflection spectroscopy, in order to assess the relationship between microstructure
and the photonic properties obtained. Photonic bandgaps have been evidenced by the corresponding stop bands in the reflection
spectra. The shape and the intensity of the Er3+
4I13/2 → 4I15/2 transition at ~1.5 μm were modified in most IOs relatively to similar matrix deposits without a photonic crystal structure,
particularly in the case of pure silica and titania IOs, where the PL peak narrowed and intensified. It was not possible at
this stage to detect Yb3+ → Er3+ ET phenomena in the IOs structures. 相似文献
11.
N. M. Antovic I. Antovic N. Svrkota 《Journal of Radioanalytical and Nuclear Chemistry》2010,284(3):605-614
232Th activities in the South Adriatic Sea-water, surface sediment, mud with detritus, seagrass (Posidonia oceanica) samples, and the mullet (Mugilidae) species Mugil cephalus, as well as soil and sand from the Montenegrin Coast, were measured using the six-crystal spectrometer PRIPYAT-2M, which
has relatively high detection efficiency and a good sensitivity, and allows a short acquisition time, and measuring samples
of any shape, without preliminary preparation and calibration measurements for different sample geometries. An average 232Th activity concentration in surface soil layer is found to be 40.33 Bq kg−1, while in sand—4.7 Bq kg−1. The absorbed dose rate in air due to 232Th gamma radiation from surface soil layer ranged from 11.76 to 63.39 nGy h−1, with a mean of 24.06 nGy h−1. Corresponding average annual effective dose rate has been found to be 0.03 mSv y−1. The absorbed dose rates due to the thorium gamma radiation in air at 1 m above sand surface on the Montenegrin beaches have
been found to be from 0.41 to 9.08 nGy h−1, while annual effective dose rates ranged from 0.0005 to 0.011 mSv y−1. 232Th activity concentration in seawater ranged from 0.06 to 0.22 Bq L−1, as in the mullet (Mugil cephalus) whole individuals from 0.63 to 1.67 Bq kg−1. Annual intake of 232Th by human consumers of this fish species has been estimated to provide an effective dose of about 0.003 mSv y−1. 相似文献
12.
Rajesh H. Panchal D. D. Rao Bipin H. Mehta A. Baburajan Ravindra H. Gaikwad 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(1):401-409
The paper deals with the transfer factors (TF) generated for a few varieties of leafy vegetables (spinach, fenugreek, and
amaranths) consumed by the locals around Tarapur atomic power station environment in India. The soil and leafy vegetable samples
collected from the ambient environment of nuclear site were used for the determination of the TFs and they were compared with
TFs generated from pot experiments under controlled conditions for 137Cs. The activity of 137Cs in soil and each vegetable was determined by gamma spectrometry using HPGe detector (35 and 160% relative efficiency) and
was reported on dry weight basis for both ambient environment and pot samples. The radioactive effluent containing 137Cs (pH ~7) from nuclear power station was used to spike the soil for pot (size 90 cm × 45 cm × 42 cm) experiment. The TFs
obtained for ambient environment and pot experiment were found to be in the range of 0.035–0.592 and 0.0054–0.29, respectively.
It is observed that TFs of ambient environment are in good agreement with those obtained in the pot experiment conducted under
controlled conditions. Further, the observed TF values at Tarapur nuclear site are comparable with the range of typical IAEA
transfer factor values for general leafy vegetation (0.11–2.9) for tropical environment. 相似文献
13.
Zal U’yun Wan Mahmood Hidayah Shahar Zaharudin Ahmad Yii Mei Wo Ahmad Sanadi Abu Bakar 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(1):265-272
The present distributions of 239+240Pu, 241Am and activity ratio of 241Am/239+240Pu in surface seawater of the Peninsular Malaysia east coast were studied. The surface seawater samples were collected at
30 identified stations during the expedition conducted in 2008. 239+240Pu activity concentrations in surface seawater of the studied area were in the range of 2.33 ± 0.20–7.95 ± 0.68 mBq/m3, meanwhile 241Am activity concentrations ranged from MDA to 1.90 ± 0.23 mBq/m3. The calculated activity ratios of 241Am/239+240Pu were varied and disperse distributed with the ranged of 0.12–0.53. The relationships between anthropogenic radionuclide
and oceanographic parameters such as turbidity and salinity were examined. The linearly relationships between 239+240Pu and oceanographic parameters are important for better understanding of its transport processes and behavior in the east
coast of Peninsular Malaysia marine environment. Thus, the differ of distribution of 239+240Pu, 241Am and 241Am/239+240Pu in the studied area mainly due to high affinity of 239+240Pu to associate with sinking particles, mobility nature of 241Am, degree of particle reactive of both anthropogenic radionuclides, scavenging and removal process; and others. 相似文献
14.
M. M. Shehata B. Scholten I. Spahn H. H. Coenen S. M. Qaim 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(2):435-442
A method for the separation of no-carrier-added arsenic radionuclides from the bulk amount of proton-irradiated GeO2 targets as well as from coproduced radiogallium was developed. The radionuclides 69Ge and 67Ga produced during irradiation of GeO2 were used as tracers for Ge and Ga in the experiments. After dissolution of the target the ratio of As(III) to As(V) was
determined via thin layer chromatography (TLC). The extraction of radioarsenic by different organic solvents from acid solutions
containing alkali iodide was studied and optimized. The influence of the concentration of various acids (HCl, HClO4, HNO3, HBr, H2SO4) as well as of KI was studied using cyclohexane. The optimum separation of radioarsenic was achieved using cyclohexane with
4.75 M HCl and 0.5 M KI and its back-extraction with a 0.1% H2O2 solution. The separation leads to high purity radioarsenic containing no radiogallium and <0.001% [69Ge]Ge. The overall radiochemical yield is 93 ± 3%. The practical application of the optimized procedure in the production
of 71As and 72As is demonstrated and batch yields achieved were in the range of 75–84% of the theoretical values. 相似文献
15.
L. Popov G. Mihailova I. Naidenov 《Journal of Radioanalytical and Nuclear Chemistry》2010,285(2):223-237
The origins of different artificial radionuclides found in soils from Northern and Southern Bulgaria was determined by measurements
of their actual concentrations and respective ratios. On the basis of the measured mobility and concentrations of the investigated
radionuclides in soils, it was estimated that after the Chernobyl accident the mean depositions of fresh 137Cs were 3.0 ± 2.5 kBq/m2 for Northern Bulgaria and 15 ± 7 kBq/m2 for Southern Bulgaria. As a result of global fallout following atmospheric nuclear weapon tests in the 1950s, mean depositions
(corrected to 1965) were calculated for Northern and Southern Bulgaria as follows: for 90Sr—1.0 ± 0.5 and 2.3 ± 1.3 kBq/m2, 238Pu—1.3 ± 0.8 and 2.8 ± 1.6 Bq/m2, 239+240Pu—15 ± 14 and 47 ± 38 Bq/m2, and 241Pu—520 ± 200 and 760 ± 260 Bq/m2. 相似文献
16.
Donald E. Dry Warren J. OldhamJr. Scott M. Bowen 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(2):635-640
The long-lived rare earth isotopes 151Sm (90 years, β
max = 76.3 keV) and 147Pm (2.62 years, β
max = 224.6 keV) are low-yield fission products that generally require lengthy separation procedures to isolate and count by
their beta emissions. We will describe novel liquid scintillation counting techniques using radioactive tracers to determine
radiochemical yields from an environmental matrix. The recovery of 151Sm is determined from the alpha decay (2.25 MeV) of 147Sm in the natural Sm carrier and is in excellent agreement with the gravimetric recovery. The 147Pm recovery is determined by the use of 145Pm (17.7 years, EC) tracer, custom-produced at LANL using an isotopically enriched target of 144Sm. We have determined the 145Pm recovery both from the 37.4 keV kα1 X-ray, and the electron-capture emissions by LSC. A comparison of these recovery methods is presented. 相似文献
17.
V. H. Martínez-Landeros Bruce E. Gnade M. A. Quevedo-López R. Ramírez-Bon 《Journal of Sol-Gel Science and Technology》2011,59(2):345-351
In this work we report the performance of permeation barriers based on organic/inorganic multilayer stacks. We have used PMMA-SiO2 (poly methyl methacrylate-silica) hybrid films synthesized through a sol–gel route as organic–inorganic components, whereas
Al2O3 thin films were used as the inorganic component. The hybrid layers were deposited by dip coating and the Al2O3 by atomic layer deposition (ALD), films were prepared on polyethylene naphthalene (PEN) substrates. The permeability of the
films and stacks is evaluated using helium as the diffusion gas in a custom made ultra-high vacuum system. The results show
that permeability for PEN is reduced from 5 × 10−3 g/m2-day to about 9 × 10−5 g/m2-day for the best multiple barrier evaluated. Increased barrier properties are due to the increasing in the path and hence
the lag-time of the permeating gas. In particular, we report the surface roughness of the different layers and its impact
on the barrier performance. The hybrid layers reduced notably the roughness of the bare PEN substrate improving the quality
of the Al2O3 layer in the barrier. The optical transmittance of the barriers in the visible region is higher than 80% in all the studied
cases. 相似文献
18.
G. D. Kim H. J. Woo H. W. Choi N. B. Kim T. K. Yang J. H. Chang K. S. Park 《Journal of Radioanalytical and Nuclear Chemistry》2007,271(3):553-558
Neutron capture cross sections on 63Cu and 186W were measured by fast neutron activation method at neutron energies from 1 to 2 MeV. Monoenergetic fast neutrons were produced
by 3H(p,n)3He reaction. Neutron energy spread by target thickness, which was assumed to be the main factor of neutron energy spread,
was estimated to be 1.5% at neutron energy of 2.077 MeV. Neutron capture cross sections on 63Cu and 186W were calculated by reference comparison method on those of 197Au(n,γ). Not only statistical errors of gamma-counts from samples but also systematic errors in the counting efficiency for
HP Ge detector and the uncertainty of areal density of samples were considered in calculating neutron capture cross section.
Estimated neutron capture cross sections on 63Cu and 186W were also compared with ENDF-6 data. 相似文献
19.
Zal U’yun Wan Mahmood Che Abd Rahim Mohamed Mei Wo Yii Zaharudin Ahmad Kamaruzzaman Ishak Abdul Kadir Ishak 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(1):107-113
Inventories and fluxes of 210Pb, 228Ra and 226Ra were determined in sediment cores collected at nine stations covering of the southern South China Sea and Malacca Straits
with the thickness of water column between 42 and 83 m depth. The inventories of 210Pb, 228Ra and 226Ra were calculated range from 0.15–2.55 Bq cm−2, 0.05–0.40 Bq cm−2 and 6.83–83.63 Bq cm−2, meanwhile the fluxes ranged from 0.005–0.079 Bq cm−2 yr−1, 0.009–0.048 Bq cm−2 yr−1 and 0.003–0.037 Bq cm−2 yr−1, respectively. The results show that the highest inventories and fluxes for 210Pb, 228Ra and 226Ra were found at station WC 01 and EC 05. Because there are additional sources of 210Pb, 228Ra and 226Ra, where water transport will brings more dissolved isotopes, influence of the transportation and deposition of suspended
particles, fast rate of regeneration and greater production of those radionuclides and others. 相似文献
20.
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