Polarization Diagram of the Electrochemical Impedance of Second Order: A Theory that Accounts for the Diffusion of Reactants

With the aim of improving diagnostic possibilities of second-order impedance spectroscopy, a theory is put forward for a polarization diagram of a second-order impedance for reactions with charge transfer. The theory takes into account the diffusion of discharging particles in the absence of their specific adsorption.     

Synthesis and Structure of the Bis- and Tris-Polyhedral Hybrid Carboranoclathrochelates with Functionalizing Biorelevant Substituents—The Derivatives of Propargylamine Iron(II) Clathrochelates with Terminal Triple C≡C Bond(s)

A synthetic strategy for obtaining structurally flexible hybrid iron(II) carboranoclatrochelates functionalized with biorelevant groups, based on a combination of a 1,3-dipolar cycloaddition reaction with nucleophilic substitution of an appropriate chloroclathrochelate precursor, was developed. In its first stage, a stepwise substitution of the dichloroclathrochelate precursor with amine N-nucleophiles of different natures in various solvents was performed. One of its two chlorine atoms with morpholine or diethylamine in dichloromethane gave reactive monohalogenoclathrochelate complexes functionalized with abiorelevant substituents. Further nucleophilic substitution of their remaining chlorine atoms with propargylamine in DMF led to morpholine- and diethylamine-functionalized monopropargylamine cage complexes, the molecules of which contain the single terminal C≡C bond. Their “click” 1,3-cycloaddition reactions in toluene with ortho-carborane-(1)-methylazide catalyzed by copper(II) acetate gave spacer-containing di- and tritopic iron(II) carboranoclatrochelates formed by a covalent linking between their different polyhedral(cage) fragments. The obtained complexes were characterized using elemental analysis, MALDI-TOF mass, UV-Vis, ¹H, ¹H{¹¹B}, ¹¹B, ¹¹B{¹H}, ¹⁹F{¹H} and ¹³C{¹H}-NMR spectra, and by a single crystal synchrotron X-ray diffraction experiment for the diethylamine-functionalized iron(II) carboranoclathrochelate. Its encapsulated iron(II) ion is situated almost in the center of the FeN₆-coordination polyhedron possessing a geometry intermediate between a trigonal prism and a trigonal antiprism with a distortion angle φ of approximately 28°. Conformation of this hybrid molecule is strongly affected by its intramolecular dihydrogen bonding: a flexibility of the carborane-terminated ribbed substituent allowed the formation of numerous C–H…H–B intramolecular interactions. The H(C) atom of this carborane core also forms the intermolecular C–H…F–B interaction with an adjacent carboranoclathrochelate molecule. The N–H…N intermolecular interaction between the diethylamine group of one hybrid molecule and the heterocyclic five-membered 1H-[1,2,3]-triazolyl fragment of the second molecule of this type caused formation of H-bonded carboranoclathrochelate dimers in the X-rayed crystal.     

Extraction of Proserine from Biological Tissues Using Unmodified Silicas

Sorption characteristics of proserine on unmodified silica with different pore sizes and specific surfaces were studied. A procedure was developed for the determination of proserine in biological materials (kidney and liver) by gas chromatography using unmodified silica. The procedure is characterized by rapidness, high sensitivity, and high precision.     

Über den Einfluß der Alkoholkomponente auf die Verseifungsgeschwindigkeit der Essigsäureester

Ohne Zusammenfassung     

Superlinear convergence of the control reduced interior point method for PDE constrained optimization

A thorough convergence analysis of the Control Reduced Interior Point Method in function space is performed. This recently proposed method is a primal interior point pathfollowing scheme with the special feature that the control variable is eliminated from the optimality system. Apart from global linear convergence we show that this method converges locally superlinearly, if the optimal solution satisfies a certain non-degeneracy condition. In numerical experiments we observe that a prototype implementation of our method behaves as predicted by our theoretical results. Supported by the DFG Research Center Matheon “Mathematics for key technologies”.     

Über die Veresterung der Benzoesäure durch alkoholische Salzsäure

Ohne ZusammenfassungEs sei mir gestattet, Herrn Prof. R. Wegscheider auch hier meinen wärmsten Dank auszudrücken für seine Ratschläge und sein Interesse an meiner Arbeit.     

Synthesis and multiparameter sensor properties of the crown‐containing thiophene derivatives

A novel ditopic receptor was constructed as a combination of bisthiophene with pyridinylvinyl and crown‐containing styryl fragments. In the receptor, the pyridine residue was able to coordinate Fe²⁺, Cd²⁺, and Mg²⁺ metal cations, whereas the oxocrown ether moiety bound with the alkaline earth metal (Mg²⁺, Ca²⁺, and Ba²⁺) cations. ¹H NMR, optical, electrochemical, and ESI‐MS results provided conclusive evidence of a complex formation through both the coordination centers of the molecule. The obtained results showed that cation complexation induces optical and electrochemical changes, particularly for each binding center. This type of multiparameter sensor provides interesting perspectives for the future design of unique sensors, promising different analytical techniques. Copyright © 2009 John Wiley & Sons, Ltd.     

Development of suitable plastic standards for X-ray fluorescence analysis

For the adoption of the EU directive “Restriction on use of certain Hazardous Substances” and “Waste Electrical and Electronic Equipment” using X-ray fluorescence analysis suitable standard materials are required.     

Investigation of W<Subscript>2</Subscript>B and β-WB high-temperature phases in coatings produced by a shaped charge explosion

Coatings containing high-temperature phases of tungsten borides W₂B and β-WB are obtained on titanium and steel targets by a shaped charge explosion. In some regions of the target, microhardness achieves ≥42 GPa. The phase composition of different regions of the coatings is examined by X-ray diffraction. The values of unit cell parameters indicate the formation of phases with variable composition. The crystal structure of β-WB is refined.     

A Steiner 5-Design on 36 Points

Up to now, all known Steiner 5-designs are on q + 1 points where q 3 (mod 4) is a prime power and the design is admitting PSL(2, q) as a group of automorphisms. In this article we present a 5-(36,6,1) design admitting PGL(2, 17) × C ₂ as a group of automorphisms. The design is unique with this automorphism group and even for the commutator group PSL(2, 17) × Id ₂ of this automorphism group there exists no further design with these parameters. We present the incidence matrix of t-orbits and block orbits.