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21.
The influence of surface structure of technical materials on results and statements of surface analytical methods has been investigated. Especially surface roughness as a typical property of rolled products has been observed. For this purpose samples of steel (technical surface, roughness up to 5 m) and silicon wafers (polished surface) have been analyzed by SNMS and GDOS in order to get information about changes of the surface roughness as function of the sputtering time and their influence on the statements about the depth profiles obtained. 相似文献
22.
Lumír Sommer 《Fresenius' Journal of Analytical Chemistry》1958,164(3):299-309
Zusammenfassung Die Chromotropsäure ist ein analytisch wertvolles Reagens auf Eisen (III)23, Chrom (VI)9, Kupfer, Niob24 und besonders auf Titan (IV). Die Reaktion mit Chromotropsäure ist die empfindlichste (pD 5,9) und in Gegenwart von Ascorbinsäure weitgehend selektive Titanreaktion.In den Titan(IV)-lösungen bilden sich mit Chromotropsäure abhängig von der Zusammensetzung und dem pH-Wert der Lösung sowie von der Konzentration der Reaktionspartner stufenweise mehrere Chelate. In den Lösungen mit Reagensüberschuß liegen folgende Chelatgleichgewichte vor: TiO2+ + 2 H2R2 TiO(RH)2
4– + 2 H+ (Absorptionsmaximum470 m), PH 0–2; TiO2+ + 2 H2R2– TiOR2
6– + 4 H+ (470 m), pH1–3,5; TiOR2
6– + H2R2 TiOR3
10– + 2 H+ (420 m), pH 3,2–7,0; TiOR2
6 + 2H2R2– TiR4
12– + 2 H + H2O (470 m), pH 1,7–2,4.Die beiden stabilen Chelate TiOR2
6– und TiOR3
10– können bei begrenzten Reaktionsbedingungen zur spektrophotoinetrischen Titanbestimmung ausgenutzt werden. Die Bestimmung bei pH 2,9–3,2 und 467m in Gegenwart von Ascorbinsäure ermöglicht die Titanbestimmung neben einer Zahl von fremden Ionen. Sie ist die für die Praxis geeignetste Methode.Herrn Prof. Dr. A. Oká zum 55. Geburtstag gewidmet.Den Firmen E. Merck, Darmstadt und Reagencia, Kralupy, bin ich für das freundliche Überlassen der Präparate der Chromotropsäure mit herzlichem Dank verpflichtet. 相似文献
23.
Manfred Sommer 《Numerical Functional Analysis & Optimization》2013,34(2):213-234
The chief purpose of this paper is to study the problem of existence of continuous selections for the metric projection and of convergence of best Lp–approximations in subspaces of polynomial spline functions defined on a real compact interval I. Nürnberger-Sommer [8] have shown that there exists a continuous selection s if and only if the numberof knots k is less than or equal to the order m of the splines. Using their construction of s the author [12] has proved that the sequence of best Lp–approximations of f converges to s(f) as ρ→∞ for every continuous function f. The main results of this paper say that also in the case when k>m there exists always a continuous selection s (it is even pointwise-Lipschitz-continuous and quasi-linear) provided that the approximation problem is restricted to certain subsets Iepsilon; of I. In addition it is shown that anologously as for k≤m the sequence of best Lpapproximations of f converges to s(f) for every continuous function f on Iε 相似文献
24.
25.
26.
Steffen Blaurock Thomas Koch Olaf Kühl Peter Lönnecke Felicite Majoumo René Sommer 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6-7):1451-1456
Substituted bifunctional phosphorus-based ligands HX(CRR') n PR"H (or -PR" 2 ) [where X = O, S, NR', (substituted) cyclopentadienyl; n = 1, 2, 3; R, R', R" = alkyl, aryl, H] were employed as bridging ligands in the synthesis of early/late bridged transition metal complexes. Synthetic routes to the bifunctional ligands were also developed. First, mononuclear complexes, such as [TpZr(OCH 2 PPh 2 ) 3 ] (Tp = trispyrazolylborato), [Cp 2 Zr(1-O-2-PHR-C 6 H 10 )(Me)] (R = 2,4,6-Pr i 3 C 6 H 2 (Tipp)), [Cp 2 Zr(SCH 2 CH 2 PHR) 2 ] (R = Ph, Mes, Tipp), and phosphinoferrocene derivatives, were prepared. These complexes are suitable precursors for the introduction of a second metal (as in, for example, [TpZr( w -OCH 2 PPh 2 ) 3 Mo(CO) 3 ]). 相似文献
27.
Alain Chaintreau Wolfgang Fieber Horst Sommer Alexis Gilbert Keita Yamada Naohiro Yoshida Alain Pagelot Detlef Moskau Aitor Moreno Jürgen Schleucher Fabiano Reniero Margaret Holland Claude Guillou Virginie Silvestre Serge Akoka Gérald S. Remaud 《Analytica chimica acta》2013
Isotopic 13C NMR spectrometry, which is able to measure intra-molecular 13C composition, is of emerging demand because of the new information provided by the 13C site-specific content of a given molecule. A systematic evaluation of instrumental behaviour is of importance to envisage isotopic 13C NMR as a routine tool. This paper describes the first collaborative study of intra-molecular 13C composition by NMR. The main goals of the ring test were to establish intra- and inter-variability of the spectrometer response. Eight instruments with different configuration were retained for the exercise on the basis of a qualification test. Reproducibility at the natural abundance of isotopic 13C NMR was then assessed on vanillin from three different origins associated with specific δ13Ci profiles. The standard deviation was, on average, between 0.9 and 1.2‰ for intra-variability. The highest standard deviation for inter-variability was 2.1‰. This is significantly higher than the internal precision but could be considered good in respect of a first ring test on a new analytical method. The standard deviation of δ13Ci in vanillin was not homogeneous over the eight carbons, with no trend either for the carbon position or for the configuration of the spectrometer. However, since the repeatability for each instrument was satisfactory, correction factors for each carbon in vanillin could be calculated to harmonize the results. 相似文献
28.
Michael G. Sommer Petra Kureljak Dr. Damijana Urankar Dr. David Schweinfurth Nikolina Stojanović Dr. Martina Bubrin Dr. Martin Gazvoda Dr. Maja Osmak Prof. Dr. Biprajit Sarkar Prof. Dr. Janez Košmrlj 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(52):17296-17299
Azocarboxamide (azcH) has been combined for the first time with [Ru–Cym] to generate metal complexes with N,N‐ and N,O‐coordination mode, [(Cym)Ru(azc)Cl] and [(Cym)Ru(azcH)Cl]+[PF6]?. Geometric and electronic structures of the complexes are reported along with their in vitro activities against different tumour cell lines and preliminary results on solution chemistry. Compound [(Cym)Ru(azc)Cl] exhibited remarkable cytotoxic properties. It was cell‐type specific and had comparable IC50 values towards both cancer cells and their drug‐resistant subline. A tenfold increase in the sensitivity towards [(Cym)Ru(azc)Cl] was noted for the tumour cells with depleted intracellular glutathione (GSH) level, suggesting the essential role of GSH in cell response to this compound. 相似文献
29.
We are proposing a lattice model with chemical input for the computer modelling of the polymer glass transition. The chemical input information is obtained by a coarse graining procedure applied to a microscopic model with full chemical detail. We use this information on Bisphenol-A-Polycarbonate to predict it's Vogel-Fulcher temperature out of a dynamic Monte Carlo Simulation. The microscopic structure of the lattice model is that of a genuine amorphous material, and the structural relaxation obeys the time temperature superposition. 相似文献
30.
Using the continous Edwards–chain model the simultaneous influence of harmonic–like constraints and of a stochastic order parameter field on the segment orientation in polymer networks is investigated. The harmonic potential reduces the orientation order parameter in comparison to the value for an unconstrained freely jointed chain. This reference value is approached from below in the case of strong topological constraints. The introduction of a stochastic order parameter field enlarges the orientation but the reference value remains the upper boundary. 相似文献