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81.
Mixtures of iridium(IV) and rhodium(III) as IrCl2-6 and RhCl3-6 are separated by ion flotation. The iridium(IV) is selectively floated from aqueous solutions of pH 2 and 0.05% Ce(IV) with either hexadecyltripropylammonium bromide (HTPAB) or hexadecyltributylammonium bromide (HTBAB). The rhodium(III) does not float under the same conditions. The floated iridium sublate is collected in n-butyl acetate without contamination by the unfloated rhodium. Data are presented also for the separation and recovery of the Ir(IV) and Rh(III) with the above surfactants, hexadecyltrimethyl-ammonium bromide (HTMAB) and hexadecyltriethylammonium bromide (HTEAB) from solutions of various sodium chloride and hydrochloric acid concentrations. The use of solvent sublation for recovering the floated iridium is examined. The separation is fast, practical, simple and does not require expensive reagents or apparatus. For these reasons, the separation of iridium and rhodium by ion flotation offers advantages over previous methods. 相似文献
82.
Maree?Ann?StuartEmail author Rod?Millar Gary?Price 《Accreditation and quality assurance》2003,8(9):405-407
The National Association of Testing Authorities, Australia has operated an accreditation program for reference material producers since 1997 with accreditation now being offered to ISO Guide 34 (2000). This paper discusses the benefits and disadvantages to both the producers and the users of reference materials (testing laboratories) and their clients of a formal system of third-party accreditation of reference material producers. The merits of using ISO Guide 34 (2000) rather than ISO/IEC 17025 as the core standard in the accreditation process are discussed. 相似文献
83.
Todd R. Downey Fabrice Meriaudeau Ali Passian Andrew Wig Thomas L. Ferrell 《Optics & Laser Technology》1999,31(4):273
The effect of variation of core and cladding index difference, Δn=ncore−ncladding, on allowable values for the guided mode transverse magnetic propagation constants within a step-index, multi-mode optical fiber is investigated. We use a iterative computational technique to calculate the propagation constants for modes inside and outside the core that satisfy the boundary conditions contained within the characteristic eigen-equation for the TM field components. Evidence of a strong dependence of the allowable propagation constants on changes of Δn is shown. 相似文献
84.
We show the existence of a high r. e. degree bounding only joins of minimal pairs and of a high2 nonbounding r. e. degree. MSC: 03D25. 相似文献
85.
Vapor species resulting from electrically-induced threshold switching and memory filament formation on the surfaces of bulk AsTeI and AsTeGe glasses are identified. The common parent species are As4 (most intense) and Te2. The results emphasize the importance of thermal mechanisms, and yield information concerning the kinetics of filament formation. 相似文献
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T. É. Bezmenova G. V. Klimusheva V. I. Kulishov S. M. Lukashov G. G. Rodé G. M. Soroka V. P. Tantsyura 《Chemistry of Heterocyclic Compounds》1977,13(8):848-851
The peculiarities of the intramolecular interaction in unsaturated five-membered cyclic sulfones as a function of their structures were studied on the basis of an analysis of the electronic absorption spectra of single crystals of isomeric -aryldihydrothiophene 1,1-dioxides at 4.2°K, the IR spectra of the molecules at 298°K, and the results of x-ray diffraction analysis of 3-phenyl-4,5-dihydrothiophene 1,1-dioxide. In addition to the inductive effect, conjugation of the SO2 group with the -electron system of 3-phenyl-4,5-dihydrothiophene 1,1-dioxide, which is manifested most appreciably in the excited electronic state, was observed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1056–1059, August, 1977. 相似文献