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11.
Kazimierz?DarowickiEmail author Waldemar?Felisiak Artur?Zieliński 《Journal of mathematical chemistry》2005,38(4):701-711
Oscillations of species concentration are phenomena accompanying several types of electrochemical and purely chemical processes.
Importance of analyzing of such processes results from both scientific and practical reasons. In the paper the authors deal
with investigation of time dependent spectra of various stages of Belousov-Zhabotinsky type chemical oscillations. As the
analytical tool the discrete wavelet transform is proposed. 相似文献
12.
Adsorptive bubble separation of zinc and cadmium cations in presence of ferric and aluminum hydroxides 总被引:2,自引:0,他引:2
Jurkiewicz K 《Journal of colloid and interface science》2005,286(2):559-563
The adsorptive bubble separation of zinc and cadmium cations from solution in the presence of ferric and aluminum hydroxides was carried out by means of Tween 80 (nonionic surfactant), and sodium laurate and stearate (anionic surfactants). The mechanism of metal removal is different depending on the nature of the surfactant used. The removal of zinc cations by adsorbing colloid flotation is higher than that of cadmium cations. It increases with increases in the amount of hydroxide precipitate and the concentration of Tween 80. The removal of zinc cations by ion flotation is lower than that of cadmium cations. It does not change with increases in the hydroxide amount. It increases, however, with increased sodium laurate or stearate concentration. Both separation methods turned out to be helpful for studying both the solution's structure and the interactions at the solution-solid interface. 相似文献
13.
Talanova GG Talanov VS Hwang HS Park C Surowiec K Bartsch RA 《Organic & biomolecular chemistry》2004,2(18):2585-2592
For an assessment of the outcomes from use of an appropriately "preorganized" calixarene-based ionophore versus its conformationally mobile prototype, solvent extraction propensities of flexible calix[4]arene di-[N-(X-sulfonyl)carboxamides] for alkali, alkaline earth metal cations, Pb2+, Ag+ and Hg2+ are compared with those for seven new rigid analogs fixed in the cone, partial cone and 1,3-alternate conformations. For each of the metal ions, the preferred calix[4]arene conformation was determined from the NMR spectra for the metal salt of the flexible ligand. Except for Ag+, flexible calix[4]arene di-[N-(X-sulfonyl)carboxamides] were found to provide greater metal ion extraction efficiency and better selectivity than the corresponding "preorganized" ionophores. 相似文献
14.
Denise Bohrer Uwe Heitmann Mao-dong Huang Helmut Becker-Ross Stefan Florek Bernhard Welz Denise Bertagnolli 《Spectrochimica Acta Part B: Atomic Spectroscopy》2007
High-resolution continuum source atomic absorption spectrometry (HR-CS AAS) has been used to investigate spectral and non-spectral interferences found with a conventional line source atomic absorption spectrometer in the determination of aluminum in pharmaceutical products containing elevated iron and sugar concentrations. A transversely heated graphite furnace was used as the atomizer in both spectrometers. The two most sensitive aluminum lines at 309.3 nm and 396.2 nm were investigated and it was found that an iron absorption line at 309.278 nm, in the vicinity of the aluminum line at 309.271 nm, could be responsible for some spectral interference. The simultaneous presence of iron and the organic components of the matrix were responsible for radiation scattering, causing high continuous and also structured background absorption at both wavelengths. The aluminum and iron absorption could not be separated in time, i.e., the iron interference could not be eliminated by optimizing the graphite furnace temperature program. However, an interference-free determination of aluminum was possible carrying out the measurements with HR-CS AAS at 396.152 nm after applying least squares background correction for the elimination of the structured background. Analytical working range and other figures of merit were determined and are presented for both wavelengths using peak volume registration (center pixel ± 1) and the center pixel only. Limits of detection and characteristic masses ranged from 1.1 to 2.5 pg and 13 to 43 pg, respectively. The method was used for the determination of the aluminum contamination in pharmaceutical formulations for iron deficiency treatment, which present iron concentrations from 10 to 50 g l− 1. Spike recoveries from 89% to 105% show that the proposed method can be satisfactorily used for the quality control of these formulations. 相似文献
15.
The reactivity of the epoxy-fulvene 1 with various nucleophiles has been examined. It is a versatile Intermediate for the preparation of spiro[4.2]hepta-1,3-diene synthons via nucleophilic addition to the C6 position followed by intramolecular cyclization of the substituted cyclopentadiene anion generated in situ. 相似文献
16.
Chuqiao Tu Kazimierz Surowiec Richard A. Bartsch 《Journal of inclusion phenomena and macrocyclic chemistry》2007,58(3-4):361-366
A di-ionizable p-tert-butylcalix[4]arene-1,3-thiacrown-5 ether extractant was synthesized. Its cone conformation and polyether ring attachment
regioselectivity were verified by NMR spectroscopy. The metal ion-complexing properties of this ligand were evaluated by solvent
extractions of metal cations from aqueous solutions into chloroform. The ligand was found to be an efficient extractant with
Ba2+ selectivity in competitive solvent extraction of alkaline earth metal cations. It also exhibits high extraction ability for
Pb2+ and for Hg2+ in single species solvent extractions. 相似文献
17.
Kazimierz?DarowickiEmail author Juliusz?Orlikowski Anna?Arutunow 《Journal of Solid State Electrochemistry》2004,8(6):352-359
Electrochemical impedance spectroscopy allows the examination of corrosion susceptibility and resistance for different construction materials, in particular the determination of the properties of their passive films. This technique makes possible the analysis of electrochemical processes in time domain, including rapid phenomena such as changes in the properties of passive films, but it has never been used for passive layer cracking examination. In many cases, fracture of the passive film under tensile stresses leads to stress corrosion cracking. Therefore, investigations of passive layer cracking on austenitic stainless steels under tensile stresses facilitate the understanding of the mechanism of stress corrosion cracking in these common engineering materials. The effect of static tensile stresses on the passive film cracking behaviour of type 304L stainless steel immersed in 0.5 M NaCl solution at room temperature has been investigated. This paper presents the impedance spectra obtained for 304L stainless steel samples at different potential values.Contribution to the 3rd Baltic Conference on Electrochemistry, Gdansk-Sobieszewo, Poland, 23–26 April 2003Dedicated to the memory of Harry B. Mark, Jr. (28 February 1934–3 March 2003) 相似文献
18.
Kazimierz Nikodem 《Aequationes Mathematicae》1991,42(1):182-189
Summary LetX be a real vector space,D a convex subset ofX and (Y, K) an order complete ordered vector space. The following sandwich theorem holds: Iff: D Y is midconvex,g: D Y {– } is midconcave andg f onD, then there exists a Jensen mappingh: D Y {– } such thatg h f onD. Using this theorem we show that a mappingf: D Y is midconvex if and only if it has Jensen support at every point ofD. Moreover, ifX is a Baire topological vector space and (Y, K) is an ordered topological vector space satisfying some additional conditions, then a mappingf: D Y is continuous whenever it has continuous Jensen support at every point ofD. As an application of these results we obtain the equality of some set-classes connected with additive and midconvex operators.Dedicated to the memory of Alexander M. Ostrowski on the occasion of the 100th anniversary of his birth 相似文献
19.
A. N. Andreyev D. D. Bogdanov V. I. Chepigin A. P. Kabachenko O. N. Malyshev Yu. Ts. Oganessian R. N. Sagajdak G. M. Ter-Akopian A. V. Yeremin F. P. Hessberger S. Hofmann V. Ninov M. Florek S. Saro M. Veselsky 《Zeitschrift für Physik A Hadrons and Nuclei》1992,344(2):225-226
The neutron-deficient isotopes257,258105 were produced in the reaction27Al+236u in 6n and 5n evaporation channels, respectively. The evaporation residues emerging from the target were separated in-flight from the projectiles and from products of different nuclear reactions by the electrostatic separator VASSILISSA [1]. The isotopes were then implanted into position-sensitive silicon detectors and identified using the --correlation method. The measured production cross-section is (5n)=(0.45±0.20)nb atE
P
=154 MeV and (6n)=(0.075±0.055) nb atE
P
=163 MeV. These cross-sections are compared with data measured for the same isotopes in the more symmetrical reaction50Ti+209Bi. 相似文献
20.