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1.
The use of radioanalytical techniques to study heavy ion induced nuclear reactions offers some distinct advantages over conventional physical techniques. Among these are (a) unit Z and A resultion in detecting the reaction products (b) high sensitivity for low probability events (c) lack of low energy thresholds or cutoffs in measuring reactcion product energy spectcra (d) economical use of accelerator time and (e) simple, portable experimental apparatus allowing broad survey measurements of reaction mechanisms at a variety of nuclear particle accelerators. We describe examples of these advantages from our research in nuclear chemistry.  相似文献   

2.
The characterization of alcohol-ethoxylate substances is a significant challenge in analytical science. Their importance in industry and society makes it necessary to have methods for their rapid, reliable characterization and quantification. This overview highlights the instrumental separation techniques for their analysis - chromatographic (e.g., gas, liquid and supercritical fluid chromatography) and electrophoretic (e.g., capillary, gel, capillary zone, and non-aqueous capillary electrophoresis and micellar electrokinetic chromatography). We summarize and explain analytical parameters for their characterization. We include selected references and examples to show the appropriateness of instrumental separation techniques for the analytical characterization of alcohol-ethoxylate substances.  相似文献   

3.
Summary The main points addressed in this study are the following: Statistical distribution patterns of published literature on instrumental analytical techniques 1981–1984; structure of scientific literature and heuristics for identifying active specialties and emerging hot spot research areas in instrumental analytical techniques; growth and growth rates of the literature in some of the identified hot research areas; quality and quantity in instrumental analytical research output.
Statistische Auswertung von Veröffentlichungen in nuklearen und anderen instrumentellen analytischen Techniken

Presented at the IAEA Advisory Group Meeting on Comparison of Nuclear Analytical Methods with Competitive Methods, October 3–7, 1986, Oak Ridge, TN, USA  相似文献   

4.
Some radiochemical analytical methods for the determination of important beta-radionuclides for decommissioning are presented. An analytical method is briefly described, which is used for the determination of 3H and 14C in steel and aluminum by combustion using commercial oxidizer. A leaching method was developed for the determination of 3H in the contaminated silica gel. A simple distillation method is presented for the determination of 14C in heavy water and wastewater sample. A method developed for the simultaneous determination of 3H, 14C, 36Cl, 55Fe, 63Ni, 41Ca and 129I in concrete, graphite, aluminium, lead, and steel is presented. The developed methods have been successfully used to analyse various materials for characterization of the waste during the decommissioning of Danish nuclear reactors.  相似文献   

5.
Summary The corrosion behavior of spent nuclear fuels under simulated geologically unsaturated and oxidizing conditions are being studied by subjecting both unirradiated and irradiated nuclear fuels to dripping groundwater. Solutions and solid materials are periodically sampled and subsequently analyzed to determine concentrations of groundwater and fuel components in these materials to elucidate corrosion mechanisms. The analyses are performed primarily by inductively coupled plasma mass spectrometry (ICP-MS). For ICP-MS we use the method of internal standardization with direct external calibration with multi-elemental standards possessing natural isotopic abundances for the determination of concentrations groundwater components and indirect instrumental response calibration for the determination of fuel components. Additionally, we are utilizing high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) to enhance our ability to determine concentrations of low-solubility actinides at ultratrace concentrations.  相似文献   

6.
As the application of electrocatalyst continues to expand, envisaging the hidden mechanisms occurring at various length scale affecting the catalytic efficiency became important. To enhance the stability of electrocatalyst and reduce the cost, it is of paramount importance to reveal the active site's dynamics (using in situ techniques for getting the real-time information) which directly affect the reactions such as oxygen evolution reaction, hydrogen evolution reaction, and so on. Since such reactions are crucial for many engineering and scientific applications, in situ characterization techniques are required, which could capture such reactions happening at a different length and time scale. This article analyzes the recent progress made in the field of electrocatalyst's characterization using in situ neutron techniques. The article also paves the future path and has delineated the future challenges involved in multiscale correlative techniques (e.g., neutron techniques in the combination of synchrotron or microscopic techniques) used for getting the multiscale (atomic to micrometer range) mechanistic information about the electrocatalyst's working and degradation.  相似文献   

7.
现代仪器分析技术在中药炮制机理研究中的应用   总被引:1,自引:0,他引:1  
现代分析技术以仪器分析为主,大量先进的现代仪器分析技术已经较广泛地应用于中药炮制机理研究领域,对阐明中药炮制的机理,提高中药饮片的质量控制水平起了很大的推动作用.本文对多种现代仪器分析技术进行介绍,并对其在中药炮制机理研究中的应用现状作一综述.  相似文献   

8.
Summary The effects of -irradiation and waste chemistry on the degradation of ethylenediaminetetraacetic acid (EDTA) in a simulant of an organic complexant mixed waste from the U.S. D.O.E’s Hanford Site have been studied. Re-identification of degradation products from an earlier radiolysis study and the results of a new chemo-degradation study indicate that glyoxylate and several chelator fragments, both nitrosated and un-nitrosated, are responsible for most of EDTA’s chemodynamics in the simulated waste.  相似文献   

9.
Marine sediments contain a record of past events and proved to be an interesting indicator matrix for this study. Instrumental neutron activation analysis and energy dispersive X-ray fluorescence techniques offer adequate sensitivity for analysis of trace elements. Grain size analysis of sediment samples before and after tsunami showed a shift in textural characteristics of the sediment which is not observed during regular monsoon and seasonal changes. Some general characteristics of sediments revealed sand content ranges between 39 and 65% and silt from 33 to 53%. Clay content was found low averaging 5.4% and varied from 2 to 13% (by weight). The concentration of Cu, Ni, Fe, Pb, Zn, Mn, Rb, Sr, Ti, K, and Ca varies from 12 to 53, 19?C46, 21,952?C36,785, 21?C39, 39?C67, 335?C856, 47?C61, 223?C400, 4,991?C8,054, 11,000?C15,791, and 5,878?C11,214?mg?kg?1, respectively. The positive correlation was observed for Cu, Ni, Ti, K, and Rb with respect to Fe. The negative correlation was observed for Ca, Sr, Zn, and Pb with respect to Fe, indicating the different source for these metals in the marine sediment. Decrease of the particle-reactive element in the tsunami impacted sediment indicates removal of clay component in the sediment, which is supported by the presence of low Th/U ratio.  相似文献   

10.
Summary The paper deals with the impact of nuclear plants and radioactive waste disposal on surface and ground water quality in their vicinity using various radiometric and radioanalytical methods. The impact of nuclear power plant Temelin on activation concentrations and fission products in hydrosphere, including tritium, was detected. The annual average tritium concentrations in Vltava River correspond to the previously calculated estimates for average and minimal quaranteed flow rates. The concentrations histories of 90Sr and 137Cs in surface water show a decreasing trend. This trend was not influenced by the nuclear power plant pilot operation. In the case of tritium, a concentration increase trend has been already observed since the startup of pilot operation. An attempt has made interpreting the sorption and diffusion data for radionuclides of cesium, strontium and tritium and technetium as representatives of multivalent elements. Sorption and diffusion data of 137Cs and 90Sr in contact with natural sorbent bentonite lead to the conclusion that both diffusion and batch sorption experiments can be simulated by an exchange model. Sorption of technetium on various bentonites plus additives materials is described. Retention of technetium on these solid phases is driven by sorption of reduced form of technetium Tc(IV).  相似文献   

11.
The present study deals with characterization of industrial grade anion exchange resins Amberlite IRN78 and Indion H-IP for which non-destructive radiotracer technique using 131I and 82Br was used. The radioisotopes were used to trace the kinetics of iodide and bromide ion-isotopic exchange reactions taking place in the two resins. It was observed that under identical experimental conditions of 40.0 °C, 1.000 g of ion exchange resins and 0.003 M labeled iodide ion solution for iodide ion-isotopic exchange reaction, the values of specific reaction rate (min?1), amount of iodide ion exchanged (mmol), initial rate of iodide ion exchange (mmol min?1) and log K d were 0.285, 0.544, 0.155 and 12.6 respectively for Amberlite IRN78 resin, which was higher than 0.093, 0.315, 0.029 and 4.9 respectively as that obtained by using Indion H-IP resins. Also at a constant temperature of 40.0 °C, as the concentration of labeled iodide ion solution increases 0.001–0.004 M, the percentage of iodide ions exchanged increases from 68.10 to 74.00 % for Amberlite IRN78 resin, which was higher than the increase of 40.20–42.80 % as observed for Indion H-IP resins. The identical trend was observed for the two resins during bromide ion-isotopic exchange reaction. The overall results indicate that that under identical experimental conditions Amberlite IRN78 resins shows superior performance over Indion H-IP resins.  相似文献   

12.
In this study, fossil (Sequoioxylon) wood from the Oligocene–Miocene transition in İstanbul, Turkey was examined using non-destructive test methods to evaluate changes in anatomical and chemical structure. Molecular changes in the cell wall structure of the wood were determined using Fourier transform infrared (FTIR) and FT-Raman spectroscopy, along with the comparison to recent wood [Sequoiadendron giganteum (Lindl.)]. We found that the cell wall carbohydrates of the fossil wood were significantly more degraded compared with lignin; FT-Raman spectroscopy revealed the degradation in more detail compared with FTIR spectroscopy. FT-Raman spectra also demonstrated that hemicellulose and holocellulose were decreased in the fossil wood. Laser-induced breakdown spectroscopy (LIBS) analysis confirmed that the mass loss was due to the decreased H and O content of the fossil wood sample and was caused by decomposition. Light microscopy also showed that fossil and recent woods have similar anatomic structures, and that the micro-morphological structure of the fossil wood was well-preserved.  相似文献   

13.
Ion exchange distribution coefficients of zirconium, ruthenium, europium, and strontium, elements found in high level nuclear waste, were determined for a new titanium hydrous oxide-type inorganic ion exchange compound. Coefficients were determined at ambient temperatures and at 85°C. The equilibrations were done in solutions simulating the composition of nuclear waste expected from the Allied-General Nuclear services, Barnwell. South Carolina plant. The progress of each reaction was monitored by adding a radiotracer of the element investigated to the simulated waste solution. Ambient temperature distribution coefficients ranging from a high of 1.2·106 for Zr to a low of 58 for Eu were obtained when equal weights of ion exchange material were used. Significantly higher distribution coefficients were found at 85°C than at ambient temperatures. This work was supported by the U. S. Energy Research Development Administration.  相似文献   

14.
Activation techniques have been used since their inception to analyse body fluids and tissues in medical research. In recent years they have also been adapted to analyse tissues in vivo. Their wider application is restricted by their complexity and relative inaccessibility, and inter-laboratory comparisons of analyses of reference materials continue to show serious discrepancies for some elements. Activation techniques contribute most to medical science when they are applied to important medical problems which cannot be solved in other ways and when they are used as reference techniques to evaluate simpler, more accessible methods.  相似文献   

15.
The automated modification of the radioanalytical determination of lead and beryllium using AutoAnalyzer modules has been developed. The method for lead determination is based on a two-phase isotope exchange of lead between the sample solution labelled with212Pb and the standard lead diethyldithiocarbamate solution in carbon tetrachloride. For the determination of beryllium a substoichiometric isotope dilution method using7Be as tracer and acetylacetone in chloroform as extractant was used. As little as 0.02 μg/ml of lead and 2 μg/ml of beryllium can be determined by the methods above. The flow diagrams of the automated procedures are presented.  相似文献   

16.
Investigations have been carried out on rats to obtain information about the selenium-containing proteins present in the microsomal fraction and especially in the endoplasmatic reticulum (ER) of the kidney. For the determination of the selenium levels instrumental neutron activation analysis via 75Se was used. After labeling of rats in vivo with 75Se-selenite and separation of the proteins in the renal homogenate and cell compartments by electrophoretic methods, the 75Se-containing proteins were detected by autoradiography. In this way, six selenium-containing proteins with molecular masses of 15, 16, 20, 23-25, 40-42 and 58-60 were found in the endoplasmatic reticulum. All of those were characterized as selenocysteine-containing selenoproteins. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

17.
Beta" alumina isomorphs with different conducting cations were produced by ion exchange in molten salts. The concentration of the main component (Al), of conducting ions (Na+, Sr++, Ba++) and of chlorides from residues of the melt inside the exchanged material was determined by instrumental neutron activation analysis (INAA).Dedicated to Professor Günther Tölg on the occasion of his 60th birthday  相似文献   

18.
Glasses are suitable host matrices for the immobilization of high-level radioactive wastes. The corrosion behaviour of nuclear waste glass in water is of considerable importance, since a potential route for returning of radionuclides to the biosphere is their leaching from the waste form into groundwater and subsequent transport by the groundwater to the surface. In this study, the preparation and characterization of borosilicate glasses of different chemical composition were investigated. Borosilicate glasses were doped with simulated nuclear waste oxides. The chemical corrosion in water of these glasses was followed by measuring the leach rates (g·cm–2·day–1), as a function of time. It was found that a simulated nuclear waste glass with the chemical composition (weight %), 15.61% Na2O, 10.39% B2O3, 45.31% SiO2, 13.42% ZnO, 6.61% TiO2 and 8.66% waste oxides, is characterized by low melting temperature and with good corrosion resistance in water. Influence of passive layers on the leaching behaviour of nuclear waste glasses is discussed.  相似文献   

19.
A multi-agency workshop was held from 25 to 27 August 2009, at the National Institute of Standards and Technology (NIST), to identify and prioritize the development of radioanalytical Certified Reference Materials (CRMs, generally provided by National Metrology Institutes; Standard Reference Materials, a CRM issued by NIST) for field and laboratory nuclear measurement methods to be used to assess the consequences of a domestic or international nuclear event. Without these CRMs, policy makers concerned with detecting proliferation and trafficking of nuclear materials, attribution and retribution following a nuclear event, and public health consequences of a nuclear event would have difficulty making decisions based on analytical data that would stand up to scientific, public, and judicial scrutiny. The workshop concentrated on three areas: post-incident Improvised Nuclear Device (IND) nuclear forensics, safeguard materials characterization, and consequence management for an IND or a Radiological Dispersion Device detonation scenario. The workshop identified specific CRM requirements to fulfill the needs for these three measurement communities. Of highest priority are: (1) isotope dilution mass spectrometry standards, specifically 233U, 236gNp, 244Pu, and 243Am, used for quantitative analysis of the respective elements that are in critically short supply and in urgent need of replenishment and certification; (2) CRMs that are urgently needed for post-detonation debris analysis of actinides and fission fragments, and (3) CRMs used for destructive and nondestructive analyses for safeguards measurements, and radioisotopes of interest in environmental matrices.  相似文献   

20.
Polycrystalline titanium samples were oxidized in pure oxygen under a 75 torr pressure, at temperatures ranging from 400°C to 500°C, and for times up to 2 hrs. A similar treatment was applied to some single crystal samples, so as to show the relationship between the crystallite orientation and the oxidation rate. The oxide films were studied by means of radioanalytical techniques, such as nuclear microanalysis, electron diffraction and ESCA, in addition to most classical techniques such as optical and electron microscopy. The complementary side of these methods is showed. They permit us to determine the contamination of the metallic surface introduced by the polishing treatments, the oxidation rate at constant temperature, and the structure of the oxides which exists in the films. These ones are especially TiO2, Ti3O5, Ti2O3 and TiO.  相似文献   

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