共查询到20条相似文献,搜索用时 31 毫秒
1.
Tongke Zhao Lei Zhang Qiuju Guo Wenbin Dong 《Journal of Radioanalytical and Nuclear Chemistry》2017,313(2):379-384
The activity concentrations of 218Po, 214Pb and 214Bi [i.e. C(218Po), C(214Pb), and C(214Bi)] and the calculated concentration ratios [i.e. 1:C(214Pb)/C(218Po):C(214Bi)/C(218Po)] are necessary for assessing radon and its progenies exposure. In this study, a measurement method of radon progenies concentrations with both high sensitivity and low uncertainty, was developed based on the Kerr method. The field measurement results of radon progeny concentrations and calculated concentration ratios in both typical indoor and outdoor environments in Beijing, China, were reported. The effects of air exchange rate on concentration ratios of radon progenies in indoor environments were discussed. 相似文献
2.
Özlem Selçuk Zorer Tekin Şahan 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(2):417-421
Gross α and gross β activities and 238U concentrations were determined in 18 surface water samples collected from Van Lake. The instrumentations used to count the
gross α and gross β activities and to determine the 238U concentrations were α/β counter of the multi-detector low background system (PIC-MPC-9604) and Inductively Coupled Plasma-Mass
Spectrometry (Thermo Scientific Element 2), respectively. Concentrations ranging from 0.001 to 0.021 Bq L−1 and from 0.111 to 2.794 Bq L−1 were observed for the gross α and β activities in surface waters, respectively. For all samples the gross β activities were
higher than the corresponding gross α activities. The results indicated that the gross α radioactive contamination in water
samples was lower than recommended values for the guideline of drinking waters and most of the gross β activities in water
samples were higher than those in the same procedure. The 238U concentrations ranged from 74.49 to 113.2 μg L−1 in surface waters. The obtained results have showed that 238U concentrations are higher than guideline values for uranium. 相似文献
3.
C. Ródenas J. Gómez J. Soto F. Maraver 《Journal of Radioanalytical and Nuclear Chemistry》2008,277(3):625-630
Spring waters used as spas may contain significant amounts of natural radionuclides, so, in some circunstances, a radiation
protection issue can arise for the population and/or the spas workers. EU has identified some groups of employees to be exposed
to natural radiation in the 1996 Euratom Directive. Among these are workers of thermal spas who may be exposed to high radiation
doses due to high radon concentrations in indoor air. In order to evaluate the potencial risk of the spring waters used as
spas, gross-α and gross-β activity, 226Ra and 222Rn concentration levels were measured in 82 spas all over the country. Gross-alpha and gross-beta concentrations ranged from
LLD to 17 Bq·l−1 and from LLD to 60 Bq·l−1, respectively. 226Ra concentrations ranged from <4 to 3,660 mBq·l−1. 222Rn concentrations ranged from <4 to 1868 Bq·l−1. Correlations between 226Ra concentrations and gross-α activity were obtained. 相似文献
4.
A. T. Abdul Rahman A. T. Ramli 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(3):653-657
A survey was carried out to determine terrestrial gammaradiation dose rates, the concentration level of 238U and 232Th and α and β activities for the surface soil in Ulu Tiram, Malaysia A 125 measurements were performed using a NaI(T1) gamma-ray
detector with crystal size of 1″ × 1″ on 15 soil samples collected from the site area about 102 km2
238U and 232Th concentrations were determined in soils by using hyper pure germanium (HPGe) gamma-ray spectrometry. The activity of α
and β from the surface soil was counted by using alpha beta counting system. The average value of 238U and 232Th concentrations in soil samples collected are 3.63±0.39 ppm within the range of 1.74±0.20 to 4.58±0.48 and 43.00±2.31 ppm
within the range of 10.68±0.76 to 82 10±4.01 ppm, respectively. The average estimate of α and β activity in soil samples collected
are 0.65±0.09 Bqg−1 and 0.68±0.08 Bqg−1, respectively. The average of terrestrial gamma-radiation dose rates measured in Ulu Tiram was found to be 200 nGy h−1, within the range of 96 to 409 nGy h−1. The population weighted outdoor annual effective dose was 1.2 mSv. 相似文献
5.
A synthesis of 15-benzoyloxybutyl-20-hydroxymethylpregn-16-enes, the intermediates in the synthesis of brassino- and ecdysteroids
modified in the D ring was performed starting with 2α,3α-isopropylidenedioxy-6,6-ethylenedyoxy-5α-androst-15-ene-17-one and
its 2β,3β-isomer through a sequence of reactions involving Michael addition, Wittig reaction and ene reaction. Structures
of the compounds were proved by the methods of two-dimensional NMR spectroscopy. 相似文献
6.
H. Dulaiova R. Peterson W. C. Burnett D. Lane-Smith 《Journal of Radioanalytical and Nuclear Chemistry》2005,263(2):361-363
Summary Radon-222 is a good natural tracer of groundwater discharge and other physical processes in the coastal ocean. Unfortunately, its usefulness is limited by the time consuming nature of collecting individual samples and traditional analysis schemes. We demonstrate here an automated multi-detector system that can be used in a continuous survey basis to assess radon activities in coastal ocean waters. The system analyses 222Rn from a constant stream of water delivered by a submersible pump to an air-water exchanger where radon in the water phase equilibrates with radon in a closed air loop. The air stream is fed to 3 commercial radon-in-air monitors connected in parallel to determine the activity of 222Rn. By running the detectors out of phase, we are able to obtain as many as 6 readings per hour with a precision of approximately ±5-15% for typical coastal seawater concentrations. 相似文献
7.
Omar M. Ali 《Monatshefte für Chemie / Chemical Monthly》2007,138(9):917-922
Summary. 2-(Arylamino)pyrimidin-4-ones were synthesized, silylated, and condensed with l,2,3,5-tetra-O-acetyl-β- d-ribofuranoside to afford the corresponding N
2-aryl protected isocytidines. Deprotection of the acetylated isocytidines using saturated NH3 in MeOH solution gave 1-(β-d-ribofuranosyl)-2-(arylamino)-4-pyrimidinones. Methyl 2-deoxy-3,5-di-O-toluyl-α/β-d-ribofuranoside was prepared and condensed with the previously silylated bases to afford the anomeric mixture of protected
nucleosides. The pure β-anomers were synthesized with better yield by treating the sodium salts of N
2-arylisocytosine derivatives with 2-deoxy-3,5-di-O-toluyl-α-d-ribofuranosyl chloride. Deprotection of the latter anomers afforded the corresponding free hydroxyl derivatives. The synthesized
free nucleosides are under antiviral and oligonucleotide investigations. 相似文献
8.
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
9.
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
10.
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
11.
Eduardo H. Montoya Pablo A. Mendoza Patricia S. Bedregal Oscar R. Baltuano Isaac M. Cohen 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(1):175-178
A method that combines the use of non-destructive neutron activation analysis and high-resolution α spectrometry has been
developed for determination of the activities of 234U and 238U in geological samples of low uranium content. The 238U content is determined by k0-based neutron activation analysis, whereas the 234U/238U relationship is measured by α spectrometry after isolation and electrodeposition of the uranium extracted from a lixiviation
with 6 M HCl. The main advantage of the method is the simplicity of the chemical operations, including the fact that the steps
destined to assure similar chemical state for the tracer and the uranium species present in the sample are not necessary.
The method was applied to soil samples from sites of the North Peru Coast. Uranium concentration range 3–40 mg/kg and the
isotopic composition correspond to natural uranium, with about 10% uncertainty. 相似文献
12.
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
13.
It was found that heating of diluted nitric or hydrochloric acids in many years stored glass beakers can result in mBq quantities
of 210Po leached from beaker walls to the solution. In the case of freshly bought beakers acid leaching of 210Po was not observed. We suppose that acid leachable 210Po in old beakers is mainly due to implantation of radon progenies (from air) into superficial layers of glass beaker walls. 相似文献
14.
Aerial parts of Sideritis cilicica Boiss. & Bal. and Sideritis bilgerana P.H. Davis (Lamiaceae) were hydrodistilled to obtain essential oils that were then analyzed by GC and GC/MS. β-Pinene (39%),
α-pinene (28%), and β-phellandrene (20%) were the main components in the oil of S. cilicica, while β-pinene (48%), and α-pinene (32%) were the major constituents in the oil of S. bilgerana. The antimicrobial activities of the oils were evaluated by using the microdilution broth method. Both of the oils showed
good inhibitory effects on C. albicans.
__________
Published in Khimiya Prirodnykh Soedinenii, No. 6, pp. 559–561, November–December, 2005. 相似文献
15.
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
16.
The activity concentrations of the Ra isotopes, 226Ra and 228Ra, as well as of 222Rn were measured in Austrian tap waters. Rn was extracted into a mineral oil cocktail not miscible with water and measured
by liquid scintillation counting using pulse-shape analysis for α/β-separation. Ra isotopes were co-precipitated with BaSO4 or concentrated by filtration through an element specific filter. EDTA solution was used to redissolve the precipitate as
well as to release the Ra from the filter. After mixing with a cocktail, the EDTA solution was measured by liquid scintillation
counting, too. From our results the effective ingestion doses for adults and 3 months old babies were calculated. 相似文献
17.
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
18.
A. A. Panasenko E. C. Gorincioi A. N. Aricu E. A. Barcari K. Deleanu P. F. Vlad 《Russian Chemical Bulletin》2004,53(12):2700-2705
One- and two-dimensional homo- and heteronuclear correlation proton, carbon, proton—proton, and proton—carbon NMR spectra of fifteen drimanic sesquiterpenoids: 11,12-dibromodrima-5,8-dien-7-one, drim-8-en-7-one, 11-hydroxydrim-8-en-7-one, 11,12-dihydroxydrim-8-en-7-one, 11-hydroxy-11,12-epoxydrim-8-en-7-one, 11-hydroxy-11,12-epoxydrim-8-en-7-one, 8,9-epoxydriman-7-one, 8,9-epoxydriman-7-ol, 11,12-diacetoxydrim-8-en-7-ol, drimane-7,8,11-triol, 7,8-isopropylidenedioxydriman-11-al, 9, 11-dihydroxydrim-7-en-6-one, drimane-7,8,9-triol, drimane-7,8,11-triol, and drim-8-ene-7,11,12-triol were studied. The proton and carbon chemical shifts were assigned.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2589–2594, December, 2004. 相似文献
19.
A furostanol saponin mixture and a known phytoecdysteroid were isolated from the roots of Helleborus orientalis Lam. Their structures were established as 26-[(β-D-glucopyranosyl)oxy]-22α-hidroxyfurosta-5,25(27)-dien-1β,3β,11α-triol (1a), 26-[(β-D-glucopyranosyl)oxy]-22α-methoxyfurosta-5,25(27)-dien-1β,3β,11α-triol (1b), and 20-hydroxy-β-ecdyson-3-O-β-D-glycoside (2). Acid hydrolysis of 1a,b gave (1β,3β,11α,22α)-22,26-dimethoxyfurosta-5,25(27)-dien-1,3,11-triol (aglycone 1) and of 2 gave 20-hydroxy-β-ecdyson (aglycone 2). Their structures were elucidated by spectral analysis.
Published in Khimiya Prirodnykh Soedinenii, No. 1, pp. 75–77, January–February, 2007. 相似文献
20.
The interactions of carotenoids (bixin, β-carotene and lycopene) with CCl3OO. in aqueous and i-propylalcohol solution saturated with air have been studied by pulse radiolysis. For bixin and β-carotene
reaction products from forming process, absorbing in the region of 650 nm, is observed with concomitant carotenoid bleaching
(bixin at 500 nm, β-carotene at 450 nm). Their rate constants from forming process are 1.78 ×108 and 7.8 ×107 mol-1 · L · s-1 respectively. However, in the case of lycopene, no such a forming process of reaction as bixin and β-carotene can be observed
although there is the bleaching reaction (rate constant 4 ×107 mol-1 · L · s-1). The results suggest that the carotenoid radical cation and an additional radical are produced in the case of bixin and
β-carotene, whereas lycopene undergoes electron transfer with CCl3OO., forming cation radical. 相似文献