Reihenentwicklungen im Weylschen Grenzkreisfall über einem halbunendlichen Intervall

Zusammenfassung Im Anschlu an eine frühere Arbeit beweisen wir im Grenzkreisfall für das Intervall s< einen Entwicklungssatz für reelle Funktionen bei vorgeschriebenen reellen Randbedingungen in s=0 und s=. Die Hilfsmittel sind: 1) der reelle Ansatz; 2) der explizite Ausdruck für die Greensche Funktion von Weyl und 3) die allgemeine Parsevalsche Gleichung.     

Optical sensor materials for the detection of amines in organic solvents

A new optical polymer-based sensor was developed, which is able to recognize amines in organic solvents with high sensitivity. Thin polymer membranes were prepared and investigated, which contain a chromogenic functional dye (reactand) that shows a significant colour change during a reversible chemical reaction with the analyte. For that purpose the azo dye 4-trifluoroacetyl-4′-[N-(methacryloxyethyl)-N-(ethyl)amino]-azobenzene (CR-465) was synthesized, which contains a trifluoroacetyl moiety (receptor for interaction with amines) and in addition, a polymerizable methacrylate group. The methacrylate group links the dye covalently to the polymer matrix and the receptor recognizes the analyte via covalent binding. For immobilisation of the dye cross-linked methacrylate polymers with different composition were used. The highly cross-linked polymer network was stable against most organic solvents and exhibited enhanced stability against mechanical strain compared to plasticized PVC. The sensitivity of the reaction between the analyte and the dye was tailored by the choice of the solvent in which the analysis of the sensor layer was performed, with equilibrium constants for 1-butylamine ranging from 80 to 2000 M⁻¹ in chloroform and DMSO, respectively. In toluene as the solvent, sensor layers typically exhibited equilibrium constants of 100 M⁻¹ for 1-butylamine, 1300 M⁻¹ for 1,4-diaminobutane and 20,000 M⁻¹ for tris-(2-aminoethyl)amine. We have also investigated the cross-linked sensor layers with respect to molecular imprinting and did not find any enhancement in selectivity through imprinting in the presence of different analyte molecules.     

Coulomb corrections to Delbrück scattering

The emission of high-energy-rays in the deexcitation of hot⁴⁰Ca and³⁹K nuclei formed in heavy-ion fusion reactions at excitation energyE _x 90 MeV has been studied. The high energy-rays were measured in coincidence with evaporation residues or light charged particles. The spectrum from the self-conjugated compound nucleus⁴⁰Ca shows an appreciable yield suppression in the Giant Dipole Resonance (GDR) energy region with respect to the³⁹K, due to isospin selection rules in the dipole-decay. The spectral line shapes of the spectra are well reproduced by using a statistical code which treats explicitly the isospin quantum number in evaluating level densities and transmission coefficients. The GDR parameters determined from the present coincidence measurements are in good agreement with the systematic in theA 40 mass region at lower bombarding energy based on the analysis of inclusive spectra.We thank M. Caldogno for technical support in the development of evaporation residues detectors. We acknowledge the participation of M. Anghinolfi, P. Corvisiero, M. Taiuti and A. Zucchiatti in the early stages of this work. Thanks are due to M. Kicinska-Habior for providing the isospin-dependent code. Discussions with B. Fornal are also gratefully acknowledged.     

PHYTOCHROME and THE DEVELOPMENT OF PHOTOPHOSPHORYLATION CAPACITY—AN APPRAISAL OF THE EXPERIMENTAL APPROACH*

Abstract— Development of the capacity for photophosphorylation (= total capacity for light-driven ATP formation) in the mustard ( Sinapis alba L.) cotyledons is strongly influenced by a red light pulse pretreatment which operates through phytochrome. The present report deals with several objections raised against the in situ assay of the rate of photophosphorylation. Experimental evidence is given in support of the assumption that the linear increase of the ATP content of the cotyledons as measured over 1.5 min after the onset of saturating white light (370 Wm^-2) in fact represents the maximum rate of photophosphorylation ('capacity'). Moreover, it is confirmed that control by phytochrome of the development of the photophosphorylation capacity and of the capacity for chlorophyll synthesis are unrelated phenomena. The failure of development of the capacity for photophosphorylation in isolated cotyledons from dark-grown seedlings cannot be attributed to deficiencies of chlorophyll synthesis.
It is concluded that the photophosphorylation response is particularly useful to study the mechanism of phytochrome (P_fr) action in case of a response which involves a threshold reaction and an interorgan (hook→cotyledon) cooperation.     

Investigation of potential-sensitive fluorescent dyes for application in nitrate sensitive polymer membranes

The applicability of various potential-sensitive dyes (PSD) for optical sensing of anions is reported. Specifically, nitrate-responsive polymer membranes have been developed which are composed of a plasticized polymer, an anion exchange catalyst, and a fluorescent dye. On exposure to nitrate, the fluorescence intensity of such membranes increases, while the wavelengths of the excitation and emission maxima remain virtually unchanged. The membranes typically are 2–4 μm thick and exhibit highest sensitivity to nitrate in the 2 to 200 mgl^–1 range. Signal changes on exposure to 100 mmol/l nitrate can be as high as +300%. The detection limit is 0.2 mgl^–1. The cationic PSD octadecyl acridine organe was tested in combination with a tin-organic and an indium-organic anion carrier rather than with tridodecylmethylammonium chloride, but both carriers were found to display no improved selectivity. Received: 2 December 1995 / Revised: 28 March 1996 / Accepted: 5 April 1996     

Perfluormethyl-element-liganden XIII [1]: ein neuer weg zu zweikernkomplexen des typs M2(CO)8E(CF3)2X (M = Mn,Re)

The reactions of M(CO)₅X ( M = Mn, Re; X = Cl, Br, I) with E₂(CF₃)₄ (E = P, As) between 50 and 90°C yield binuclear complexes of the type M₂(CO)₈E(CF₃)₂X with two different bridging ligands, the formation of which is influenced by M (Mn > Re), E (P > As) , and X(I > Br > Cl). The main by-product is the symmetrical system M₂(CO)₈[E(CF₃)₂]₂, which is however not formed by the partial replacement of X by E(CF₃)₂ since this reaction requires temperatures above 120°C. The observed products can be explained by a three-step reaction path starting with the cleavage of E₂(CF₃)₄ followed by the subtitution of a cis-CO group in the M(CO)₅X component by M(CO)₅E(CF₃)₂ and the ring closure.     

Supramolecular phthalocyanine dimers based on the secondary dialkylammonium cation/dibenzo-24-crown-8 recognition motif

[formula: see text] New unsymmetrically substituted DB24C8-phthalocyanines, which are able to form complexes with suitable dialkylammonium cations, have been prepared. These complexes most probably have a pseudorotaxane geometry.     

Expanding the Topological Landscape by a G-Column Flip of a Parallel G-Quadruplex

Canonical G-quadruplexes can adopt a variety of different topologies depending on the arrangement of propeller, lateral, or diagonal loops connecting the four G-columns. A novel intramolecular G-quadruplex structure is derived through inversion of the last G-tract of a three-layered parallel fold, associated with the transition of a single propeller into a lateral loop. The resulting (3+1) hybrid fold features three syn⋅anti⋅anti⋅anti G-tetrads with a 3’-terminal all-syn G-column. Although the ability of forming a duplex stem-loop between G-tracts seems beneficial for a propeller-to-lateral loop rearrangement, unmodified G-rich sequences resist folding into the new (3+1) topology. However, refolding can be driven by the incorporation of syn-favoring guanosine analogues into positions of the fourth G-stretch. The presented hybrid-type G-quadruplex structure as determined by NMR spectroscopy may provide for an additional scaffold in quadruplex-based technologies.