共查询到20条相似文献,搜索用时 15 毫秒
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Inoue Mutsuo Yoneoka Shuichiro Ochiai Shinya Morokado Toshiki Uemura Hiroaki Nagao Seiya 《Journal of Radioanalytical and Nuclear Chemistry》2018,316(3):1233-1241
Journal of Radioanalytical and Nuclear Chemistry - We investigated radiocesium concentrations in the suspended solids (SS) of two large rivers discharging into the Sea of Japan. Higher 134Cs... 相似文献
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Juranová Eva Hanslík Eduard Dulanská Silvia Grísa Tomáš Sedlářová Barbora Marešová Diana 《Journal of Radioanalytical and Nuclear Chemistry》2020,324(3):983-991
Journal of Radioanalytical and Nuclear Chemistry - The purpose of the study is to explore the sorption behaviour of anthropogenic radionuclides in the Vltava River catchment in the Czech Republic,... 相似文献
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U. Sansone Chang Kyu Kim G. Kis-Benedek R. Schorn E. Zeiller A. Qaribov V. Huseynov A. Chupov 《Journal of Radioanalytical and Nuclear Chemistry》2008,277(2):357-364
In the frame of an International Atomic Energy Agency Technical Cooperation project, a radiological survey was performed in
the Araks and Kura Rivers (Azerbaijan). Sediment samples, and where available, aquatic plants were collected along these two
rivers and their inflow and tributary rivers. 137Cs, 238U, 234U, 239+240Pu, 238Pu, 90Sr and 241Am activity concentrations were measured. The radionuclide levels measured were relatively low, and in most cases below the
detection limit, as compared with those from other areas of the world which have been directly affected by effluents from
nuclear installations or influenced by the Chernobyl accident. The results indicated that the radionuclides are of natural
origin or attributable to the atmospheric fallout from nuclear weapons tests or to the Chernobyl-derived deposition. 相似文献
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Shubo Deng Gang Yu Zhongxi Chen Di Wu Fujun Xia Neng Jiang 《Colloids and surfaces. A, Physicochemical and engineering aspects》2009,332(1):63-69
The concentration and size of suspended solids (SS) in the treated produced water beyond the criteria of injection water in Daqing oilfield have raised great concerns in recent years. The SS in produced water from water, polymer and alkali–surfactant–polymer (ASP) flooding were successfully separated and characterized using some analytical techniques in this study. X-ray fluorescence (XRF), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and heating method reveal that some organic compounds besides crude oil were present in the SS samples, and polyacrylamide was found in the SS from polymer and ASP flooding. X-ray diffraction (XRD) shows some crystal inorganic substances such as SiO2, Fe2O3, Fe3O4, and BaSO4 in the SS samples, and XPS analysis indicated that several iron compounds with different valences were present in the three SS samples. The mean diameters of three SS samples were 22.89, 11.28 and 17.61 μm, respectively. Most importantly, the aggregates formed by the SS and oil droplets as well as the small SS adsorbed on the surface of oil droplets were observed using a microscope, indicating that the SS can be removed with crude oil, and crude oil also contributes to the determination of the SS values. 相似文献
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C. Jech 《Journal of Radioanalytical and Nuclear Chemistry》1976,30(2):457-461
It is well known that by the coordinated action of atoms arranged in rows and planes in the crystal lattice, the motion of
charged particles such as protons, alpha particles and heavier ions can be influenced so that their range in the single crystals
is considerably enhanced in low-index directions. A technique has been developed based on such enhanced penetration (channeling)
of radioactive atoms (220Rn) emitted by recoil with a 100 keV energy from a224Ra point source to record channeling patterns which show the crystal structure. The radioactive recoil atoms impinging from
this source on the surface of a single crystal penetrate deeper in places where their direction of impact is identical with
low index crystal directions and planes. These places can be visualized by autoradiography when having first stripped a thin
layer from the surface corresponding to the random range of the atoms. This technique is generally applicable in close packed
crystals and gives information about the crystal structure of very thin surface layers. 相似文献
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P. Beneš M. Černík P. Lam Ramos 《Journal of Radioanalytical and Nuclear Chemistry》1992,159(2):201-218
The paper aims at the analysis of principal factors affecting the interaction of radiocesium with freshwater solids, important for the migration of radiocesium in rivers. Uptake and release of radiocesium by bottom sediment and suspended solids from a small stream were studied as a function of contact time during the uptake and releases, of concentration of the solid phases and of temperature, using laboratory model experiments. Kinetics of the uptake were found to be singificantly affected by temperature and concentration of the solid phase. The kinetics and the concentration effect can be quantitatively described using kinetic model of two parallel or consecutive reactions. Kinetic parameters for the model were determined. Distribution coefficient Kd is independent of sediment concentration in the range of 20–70 mg·dm?3 but passes through a maximum at higher concentration values. Release of radiocesium adsorbed on the freshwater solids was found to be quite rapid and a simple kinetics of the release from freshwater solids was observed. The amount released decreased with increasing contact time of radiocesium with solid phase. Quantitative evaluation of the release revealed partial irreversibility of radiocesium uptake on the solids studied. Results obtained are compared with literature data and conclusions are drawn on the importance of the factors studied for modeling of radiocesium migration in rivers. 相似文献
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P. Beneš P. Lam Ramos R. Poliak 《Journal of Radioanalytical and Nuclear Chemistry》1989,133(2):359-376
The paper aims at the analysis of principal factors affecting the interaction of radiocesium with freshwater solids, important for the migration of radiocesium in rivers. Uptake of radiocesium by bottom sediments and suspended solids from small streams was studied as a function of pH and composition of aqueous phase, of the concentration of cesium in water and of the composition of freshwater solids, using laboratory model experiments. pH had negligible effect on the uptake in the pH range 5–9, the uptake decreased at pH values less than 3–5 depending on the nature and concentration of the solids. Addition of cations suppressed the uptake in the order K+>Na+>Ca2+, the suppression began at 0.001, 0.01 and 0.1 mol.dm?3 concentration, respectively. Increase in cesium concentration in water caused a decrease of radiocesium uptake, but at very low concentrations of cesium combined with higher concentration of sediment (2g·dm?3) the uptake was independent of cesium concentration. Removal of carbonates, oxidic coatings and organic matter from a sediment did not affect the sorption properties of the sediment. The nature of the effects found confirms that cesium is sorbed mainly by clay components of freshwater solids. Results obtained are compared with literature data and conclusions are drawn on the importance of the factors studied for modelling of radiocesium migration in rivers. 相似文献
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Bernard L. Hirschbein George M. Whitesides 《Applied biochemistry and biotechnology》1982,7(3):157-176
Agarose beads containing immobilized enzymes or affinity ligands have been made magnetically responsive by adsorbing freshly
precipitated magnetite on their surface. These beads are used for affinity adsorption of proteins from complex mixtures containing
suspended solids. The magnetically responsive beads and the unwanted (diamagnetic) solids are then separated by magnetic filtration.
This magnetic adsorption scheme for direct affinity separation of enzymes from mixtures containing suspended solids is compared
with a similar, but nonmagnetic, scheme in which the affinity matrix is supported on fiberglass cloth. The enzyme is allowed
to adsorb in this matrix, and the matrix is simply removed physically from the suspension to achieve separation from the unwanted
solids. The two methods seem comparable in their ability to separate a desired enzymatic activity. The magnetic methods are
technically the more complex of the two, but are significantly the more rapid. The efficiency of separation of diamagnetic
and ferrimagnetic solids in these biological systems by high gradient magnetic filtration is good. 相似文献
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Kinetic equations for the decay of the free radicals in polymeric solids are given for the following assumptions on which they are based: (1) two simultaneous first-order but physically separated decay reactions; (2) two simultaneous noninteracting second-order decay reactions; (3) combined simultaneous but intermingled first- and second-order decay reactions; (4) the same but for independent, i.e., not intermingled, first- and second-order decay reactions; (5) a second-order decay reaction in the presence of some free radicals that do not decay; and (6) a first-order decay reaction in the presence of some free radicals that do not decay. In all of the above physical systems the total concentration only can be measured. Hence the above kinetic equations refer to the change of the total concentration with time. It is found that the data for the decay of the free radicals in irradiated isotactic polypropylene and 61% styrene-39% butadiene block copolymer agree best with the equations for the second-order decay in the presence of a fraction of nondecaying free radicals. 相似文献
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The experimental difficulties associated with differential thermal analysis (DTA) are reviewed. Quantitative work has always required calibration of the equipment, and conventional solid diluents have serious disadvantages. It is shown that calibration is not strictly necessary, given appropriate conditions. Dilute suspensions of polymer crystals in organic liquids provide ideal media for DTA when used as diluent and as reference material. Convection currents are suppressed and the medium can support fine particles of the solid under test, even when the solid has a relatively high specific gravity. The new theory and techniques have been tested experimentally by measuring the heats of fusion of two inorganic salt hydrates. The results are in excellent agreement with literature values. A novel arrangement with a double thermocouple junction is shown to have considerable potentialities as a means of making precise measurements quite simply. 相似文献
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Nam Chil Woo 《Journal of Radioanalytical and Nuclear Chemistry》2001,249(2):271-278
The sorption of radionuclides on the wall of polypropylene centrifugetubes used for the batch migration study has been investigated. The parametersvaried were solution acidity, contact time, presence and physicochemical propertiesof geomedia. The radionuclides were 46Sc, 60Co, 75Se, 85Sr, 134Cs and 241Am, whichwere all gamma-ray emitters. It has been found that the sorption of radionuclideson the tube wall increased somewhat with increasing solution pH and the contactperiod in the control experiment, but decreased with increasing the cationexchange capacity of geologic materials in the batch experiment. Effects ofsorption on tube wall in the migration study is negligible in most but notall situations and should be corrected, not by the control experiment butby the batch experiment. 相似文献
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R. F. Talipov I. M. Safarov G. R. Talipova M. G. Safarov 《Reaction Kinetics and Catalysis Letters》1997,61(1):63-68
A mechanism for formation of hydrogenated furans in the reaction of α-olefins with formaldehyde is suggested. Based on kinetic
data, it involves the equilibrium addition of protonated formaldehyde to the olefin. 相似文献
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A new approach is proposed to derive the equation of elementary excitation motion along chains and it is used to obtain an important correction of the equation. 相似文献
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M. C. Duff S. L. Crump R. J. Ray W. E. Cotham S. LaMont D. Beals K. Mount R. D. Koons J. Leggitt 《Journal of Radioanalytical and Nuclear Chemistry》2008,275(3):579-593
The Federal Bureau of Investigation (FBI) Laboratory currently does not have on site facilities for handling radioactive evidentiary
materials and there are no established FBI methods or procedures for decontaminating high explosive (HE) evidence while maintaining
evidentiary value. One experimental method for the isolation of HE residue involves using solid phase microextraction (SPME)
fibers to remove residue of interest. Due to their high affinity for organics, SPME fibers should have little affinity for
most metals. However, no studies have measured the affinity of radionuclides for SPME fibers. The focus of this research was
to examine the affinity of dissolved radionuclide (239/240Pu, 238U, 237Np, 85Sr, 133Ba, 137Cs, 60Co and 226Ra) and stable radionuclide surrogate metals (Sr, Co, Ir, Re, Ni, Ba, Cs, Nb, Ru, and Nd) for SPME fibers at the exposure
conditions that favor the uptake of HE residues. Our results from radiochemical and mass spectrometric analyses indicate these
metals have little measurable affinity for these SPME fibers during conditions that are conducive to HE residue uptake with
subsequent analysis by liquid or gas phase chromatography with mass spectrometric detection. 相似文献
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H. Meier E. Zimmerhackl G. Zeitler P. Menge W. Hecker 《Journal of Radioanalytical and Nuclear Chemistry》1987,109(1):139-151
An application of distribution coefficients in transport models must take into account, among others, influences of solution-to-solid (V/M) ratios. Therefore, with batch tests the dependence of sorption and desorption coefficients on V/M in rock-groundwater systems of the Gorleben site was investigated. Experiments show that sorption (RS) and desorption (RD) coefficients of Ra, U, Pa and Ac decrease with decreasing liquid/solid ratios. In order to understand the V/M-effect sorption isotherms for different V/M ratios and, moreover, quantities for characterizing specific sorption of nuclides have been measured. The results allow the postulation of a model for describing approximately RS-V/M-relationships of different nuclide/rock/groundwater system with specific parameters.Paper presented at International Conference on Nuclear and Radiochemistry, Lindau, October 8–12, 1984, FRG 相似文献
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An innovative experimental technique, which was devised to study the effects of temperature and pressure on the rate of hydrate formation at the surface of a gas bubble suspended in a stagnant water phase, was adapted in this work. Under such conditions, the hydrate-growth process is free from dynamic mass transfer factors. The rate of hydrate formation of methane and carbon dioxide has been systematically studied. The measured hydrate-growth data were correlated by using the molar Gibbs free energy as driving force. In the course of the experiments, some interesting surface phenomena were observed. 相似文献