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101.
M. K. Pham M. Betti P. P. Povinec M. Benmansour V. B��nger J. Drefvelin C. Engeler J. M. Flemal C. Gasc�� J. Guillevic R. Gurriaran M. Groening J. D. Happel J. Herrmann S. Klemola M. Kloster G. Kanisch K. Leonard S. Long S. Nielsen J.-S. Oh P. U. Rieth I. ?stergren H. Pettersson N. Pinhao L. Pujol K. Sato J. Schikowski Z. Varga V. P. Vartti J. Zheng 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(2):603-611
A new certified reference material (CRM) for radionuclides in sea water from the Irish sea (IAEA-443) is described and the results of the certification process are presented. Ten radionuclides (3H, 40K, 90Sr, 137Cs, 234U, 235U, 238U, 238Pu, 239+240Pu and 241Am) have been certified, and information values on massic activities with 95% confidence intervals are given for four radionuclides (230Th, 232Th, 239Pu and 240Pu). Results for less frequently reported radionuclides (99Tc, 228Th, 237Np and 241Pu) are also reported. The CRM can be used for quality assurance/quality control of the analysis of radionuclides in water samples, for the development and validation of analytical methods and for training purposes. The material is available in 5 L units from IAEA (http://nucleus.iaea.org/rpst/index.htm). 相似文献
102.
P. K��d��r K. Varga B. Baja Z. N��meth N. Vajda Zs. Stef��nka L. K?v��r I. Cserny J. T��th T. Pint��r J. Schunk 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(3):943-954
Within the frame of a joint project, the accumulation of the uranium and transuranium (TRU) species on some structural materials used at Soviet made VVER-type pressurized water reactors (such as heat exchanger tube of steam generators and stainless steel canister material) has been studied. The experiments were carried out in a laboratory model system. During the sorption studies, boric acid coolants provided by the Paks Nuclear Power Plant (Paks NPP) were circulated for a period of 30 h. Solution and tube samples obtained in the course of above experiments were analyzed by independent methods (??- and ??-spectrometry, ICP-MS, SEM-EDX, voltammetry and XPS). The experimental results reveal that: (i) the surface excess of the TRU nuclides studied is extremely low (less than 1% of a monolayer coverage); (ii) the surface excess of uranium species measured on the SG tube surfaces is significantly higher, after 30 h sorption period (??sample = 1.0 ??g cm?2 U ? 3.7 × 10?9 mol cm?2 UO2) exceeds a monolayer coverage; (iii) the mechanistic features of the contamination processes (specific or non-specific adsorption, deposition of colloidal and/or disperse particles) depend decisively upon the nature of the studied radionuclides and the chemical structure and composition of the oxide layer formed on stainless steel surfaces. 相似文献
103.
104.
Laura Hinojosa Reyes Jorge Luis Guzm��n Mar Aracely Hern��ndez-Ram��rez Juan Manuel Peralta-Hern��ndez Juan Manuel Alfaro Barbosa H. M. Skip Kingston 《Mikrochimica acta》2011,172(1-2):3-14
The application of microwave-assisted extraction (MAE) to the work-up of environmental and biological samples in the study of mercury speciation analysis has increased in recent years and is now increasingly accepted as a standard approach. The review provides a brief theoretical background of microwave heating and the basic principles of microwave energy used for extraction. The advantages and disadvantages of (a) MAE techniques, (b) the influence of the main parameters affecting the extraction, (c) statistical optimization approaches, and (d) strategies for method validation also are highlighted. Recent applications of MAE to mercury species analyses in biological samples, soils, sediments, and crude oil samples are surveyed and critically reviewed. In addition, comparisons of its use with other well-established extraction procedures are discussed. Figure
Microwave-assisted extraction has become a very useful sample preparation techniques in the study of mercury speciation in environmental and biological samples 相似文献
105.
V. Yu. Rad��kov G. G. Skvortsov G. K. Fukin K. A. Lyssenko M. Yu. Antipin A. A. Trifonov 《Russian Chemical Bulletin》2011,60(5):803-808
The reaction of lithium silylamide [??o-MeOC6H4N(SiMe3)}Li(OEt2)]2 with 2 equiv. of benzonitrile in THF at ??20 °C affords the lithium derivative of the new tridentate amidinate ligand [{o-MeOC6H4NC(Ph)N(SiMe3)}Li]2. The X-ray diffraction study showed that this complex has a dimeric structure due to the coordination of the N atoms and the ether group of one amidinate ligand to different Li atoms. The reaction of anhydrous YCl3 with the resulting complex in THF gives the monoamidinate complex [{o-MeOC6H4NC(Ph)N(SiMe3)}YCl2(THF)2]2 regardless of the reagent ratio. The latter has a dimeric structure in the crystalline state as a result of the presence of two ??2-bridging Cl atoms that link Y atoms. The ether groups of the amidinate ligands are not involved in the metal-ligand interaction. 相似文献
106.
I. V. Sedov P. E. Matkovskii L. N. Russiyan E. I. Knerel��man I. G. Shunina 《Russian Chemical Bulletin》2011,60(9):1880-1884
Gas volumometry, gas chromatography, mass spectrometry, and ESR were used to study reactions of methylaluminoxane (MAO) and Me3Al with Cp4Zr, Cp4Ti, and 2,2,6,6-tetra-methylpiperidine-1-oxyl (TEMPO). It was shown that the reaction is accompanied by evolution of methane, whose amount exceeds the initial concentration of the starting metallocene or free radical by a few hundred times, but in all the cases is no more than 15% of the starting amount of the Me??Al fragments in the organoaluminum compound. Metal-centered radicals were detected by ESR in the systems with Zr and Ti metallocene derivatives. Mechanism of the observed reactions is discussed. 相似文献
107.
A. B. Burdukov M. A. Vershinin N. V. Pervukhina S. G. Kozlova I. V. El��tsov Ya. Z. Voloshin 《Russian Chemical Bulletin》2011,60(12):2504-2509
Quantum chemical calculations were performed at the DFT level for the boron-capped dichloro-substituted tris-dioximate iron(II) clathrochelate and cyclohexane and 1,4-dioxane radicals. The 1,4-dioxane and cyclohexane radicals are nucleophiles towards the macrobicyclic precursor studied. The reaction of this clathrochelate with cyclohexane in the presence of a free-radical initiator resulted in substitution of a chlorine atom by a cyclohexyl fragment. The compound obtained was characterized by elemental analysis, IR spectroscopy, 1H and 13C{1H} NMR, and single-crystal X-ray diffraction data. 相似文献
108.
The authors introduce a new class of finite dimensional algebras called extended canonical, and determine the shape of their derived categories. Extended canonical algebras arise from a canonical algebra ?? by onepoint extension or coextension by an indecomposable projective module. Our main results concern the case of negative Euler characteristic of the corresponding weighted projective line ${\mathbb{X}}$ ; more specifically we establish, for a base field of arbitrary characteristic, a link to the Fuchsian singularity R of ${\mathbb{X}}$ which for the base field of complex numbers is isomorphic to an algebra of automorphic forms. By means of a recent result of Orlov we show that the triangulated category of the graded singularities of R (in the sense of Buchweitz and Orlov) admits a tilting object whose endomorphism ring is the corresponding extended canonical algebra. Of particular interest are those cases where the attached Coxeter transformation has spectral radius one. A K-theoretic analysis then shows that this happens exactly for 38 cases including Arnold??s 14 exceptional unimodal singularities. The paper is related to recent independent work by Kajiura, Saito and Takahashi. 相似文献
109.
In this survey recent results about q-analogues of some classical theorems in extremal set theory are collected. They are related to determining the chromatic number of the q-analogues of Kneser graphs. For the proof one needs results on the number of 0-secant subspaces of point sets, so in the second part of the paper recent results on the structure of point sets having few 0-secant subspaces are discussed. Our attention is focussed on the planar case, where various stability results are given. 相似文献
110.
Va?ek Chv��tal 《Graphs and Combinatorics》2011,27(2):171-175
We show that the method of counting closed walks in strongly regular graphs rules out no parameter sets other than those ruled
out by the method of counting eigenvalue multiplicities. 相似文献