Inductive Construction of Repletion

The aim of this paper is to give a purely logical construction of repletion, i.e. the reflection of an arbitrary set to a replete one. Replete sets within constructive logic were introduced independently by M. Hyland and P. Taylor as the most restrictive but sufficiently general notion of predomain suitable for the purposes of denotational semantics à la Scott.For any set A its repletion R(A) appears as an inductively defined subset of S²(A) (A S) S which can be expressed within the internal language of a model of type theory. More explicitly, R(A) is the least subset of S²(A) containing all point filters and closed under a class of generalised limit processes. Improvements of our construction arise from several results saying that it suffices for the purpose of repletion to consider more restrictive classes of generalised limit processes.     

Alkaloide aus Vincetoxicum officinale Moench

Zusammenfassung In Vincetoxicum officinale Moench, wurden erstmalig Alkaloide nachgewiesen. Die chromatographische Trennung ergab zwei Hauptbasen, von denen sich die eine als Tylophorin identifizieren ließ. Die Konstitution der zweiten neuen Base wurde weitgehend aufgeklärt.

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For the first time, alkaloids have been detected in Vincetoxicum officinale Moench. Chromatographic separation yielded two major bases, one of which has been identified as tylophorine. The structur of the second, new base has been elucidated to a considerable extent.

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Mit 2 Abbildungen     

Lidar calibration experiments

A series of atmospheric aerosol diffusion experiments combined with lidar detection was conducted to evaluate and calibrate an existing retrieval algorithm for aerosol backscatter lidar systems. The calibration experiments made use of two (almost) identical mini-lidar systems for aerosol cloud detection to test the reproducibility and uncertainty of lidars. Lidar data were obtained from both single-ended and double-ended lidar configurations. A backstop was introduced in one of the experiments and a new method was developed where information obtained from the backstop can be used in the inversion algorithm. Independent in-situ aerosol plume concentrations were obtained from a simultaneous tracer gas experiment with SF, and comparisons with the two lidars were made. The study shows that the reproducibility of the lidars is within 15%, including measurements from both sides of a plume. The correspondence with in-situ measurements is excellent. Finally, the new backstop method is able to reveal information which can close the lidar equation by obtaining the relation between backscatter and extinction in an aerosol cloud. Received: 21 December 1995 / Revised version: 25 July 1996     

Derivate des 1.4-Dioxan-2-ons

Zusammenfassung Es wird die Synthese einer Anzahl von spasmolytisch wirksamen 1.4-Dioxan-2-onen aus Benzilsäure und 1.2-Diolen beschrieben.

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Derivatives of 1.4-dioxan-2-on

The synthesis of some 1.4-dioxan-2-ons is described; they are spasmolyticals.

     

Decay studies of K isomers in 254No

A detailed $ \gamma$ spectroscopic decay study of two K isomers in ²⁵⁴No was performed. In addition to the previously reported $ \gamma$ lines two new transitions of E = 778 , 856keV could be attributed to the decay pattern of ^254m1No ( T _1/2 = 275±7 ms). The population of an excited band built up on this isomer ( $\ensuremath K^{\pi} =8^{-}$ by the decay of ^254m2No ( T _1/2 = 198±13 μs) could be proven by measuring delayed $ \gamma$ - $ \gamma$ coincidences between transitions stemming from the decay of both isomeric states. The energies of the band members could be established up to $\ensuremath I^{\pi} = 15^{-}$ . A spontaneous fission branch of (2.0±1.2)×10^-4 was measured for ^254m1No , an upper limit of $ \le$ 1.2×10^-4 was estimated for ^254m2No . These values demonstrate the high stability of multi-quasiparticle configurations against spontaneous fission. Evidence for an $ \alpha$ decay branch of ^254m1No in the order of 1×10^-4 was found.     

Über Evonymus-Alkaloide, 3. Mitt.: Konstitution und Konfiguration von Evonin und Evonolin (aus Evonymus europaea L.)

Zusammenfassung In Fortsetzung unserer Untersuchungen^1,2 wurde die Konstitution und die relative Konfiguration des Evonins und eines Nebenalkaloides, des Evonolins, entsprechend den Formeln (1) bzw. (2) ermittelt.

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Evonymus alkaloids, III. The constitution and configuration of evonine and evonoline

In continuation of our earlier studies^1,2 the constitution and relative configuration of evonine (1) and an accompanying alkaloid, evonolin (2), were determined.

     

Poly(vinyl pyrrolidone-co-vinyl acetate)–cellulose acetate blends as novel pervaporation membranes for ethanol–ethyl tertio-butyl ether separation

The design of high-performance pervaporation membranes for the selective removal of ethanol from ethyl t-butyl ether (ETBE) was performed by using the polymer blending method. Binary blends of cellulose acetate or cellulose triacetate with a specific copolymer, poly(vinyl pyrrolidone-co-vinyl acetate), were studied by pycnometry, differential scanning calorimetry, infrared spectroscopy, solvent–mixture sorption and pervaporation.The sorption extent and especially the permeability of the blend membranes to the ethanol–ETBE azeotropic mixture increases greatly with the copolymer content with quasi-constant and high selectivity. This behavior is attributed to the specific interactions of amide C=O groups (a strong Lewis-base) in the copolymer with ethanol. The resulting high-performance membranes were stable at low temperatures but showed some performance alteration, at temperatures exceeding 80°C, because of copolymer extraction by the solvent mixture. The different behaviors of the same membrane at high and low temperatures were explained in terms of copolymer chain reptation, which was possible in the rubbery state but not in the glassy state. A crosslinking of the two polymers via urethane bonds led to perfectly stable high-performance membranes for the target application. © 1997 John Wiley & Sons, Ltd.