Diosgenin aus Yams als Hormonvorstufe

Diosgenin as a sapogenin is the aglycone of the saponine dioscin. It is occuring in plants such as yam, from which it is isolated on industrial scale since the 1940ies. Plant diosgenin is a starting substance for the synthesis of human, i.e. animal, hormones and “the pill”, which as a hormonal contraception represents a revolution in the control of human sexuality. History, isolation and spectroscopy of this complex sapogenin are reported. This article extends the briskly discussed feature “50 years pill in Germany” (Streller & Roth, ChiuZ, 2011 [( 1 ) ]) by a particular compound example. It belongs to the series on isolation and spectroscopy of natural products in this journal.     

Improved high-efficiency organic solar cells via incorporation of a conjugated polyelectrolyte interlayer

The power conversion efficiencies of bulk heterojunction (BHJ) solar cells can be increased from 5 to 6.5% by incorporating an ultrathin conjugated polyelectrolyte (CPE) layer between the active layer and the metal cathode. Poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT) and [6,6]-phenyl C(71) butyric acid methyl ester (PC(71)BM) were chosen for the photoactive layer. CPEs with cationic polythiophenes, in both homopolymer and block copolymer configurations, were used to improve the electronic characteristics. The significant improvement in device performance and the simplicity of fabrication by solution processing suggest a promising and practical pathway for improving polymer solar cells with high efficiencies.     

The efficiency of light-emitting electrochemical cells

We report on the efficiency behavior of light-emitting electrochemical cells (LECs) fabricated from a methyl-substituted ladder-type poly(p-phenylene) (mLPPP) that was blended with a crown ether based solid state electrolyte. Unlike organic light-emitting diodes (oLEDs) utilizing mLPPP as an active layer, the LECs suffer from a loss of efficiency at elevated current densities. From scan rate dependent studies we deduce that this efficiency drop is not only due to device decomposition upon high voltage operation and we also reveal the intrinsic mode of LEC operation. The decreasing width of the intrinsic region between the p- and n-type doped zones upon ongoing pin-junction formation causes distinct (either field or electrode induced) luminance quenching effects.     

High density matter at RHIC

QCD predicts a phase transition between hadronic matter and a quark-gluon plasma at high energy density. The relativistic heavy ion collider (RHIC) at Brookhaven National Laboratory is a new facility dedicated to the experimental study of matter under extreme conditions. Already the first round of experimental results at RHIC indicated that the conditions to create a new state of matter are indeed reached in the collisions of heavy nuclei. Studies of particle spectra and their correlations at low transverse momenta provide evidence of strong pressure gradients in the highly interacting dense medium and hint that we observe a system in thermal equilibrium. Recent runs with high statistics allow us to explore the regime of hard-scattering processes where the suppression of hadrons at large transverse momentum, and quenching of di-jets are observed thus providing further evidence for extreme high density matter created in collisions at RHIC.     

Detection and identification of individual antigen molecules in human serum with pulsed semiconductor lasers

-11 M without separation steps. Received: 25 July 1997     

Die Berücksichtigung von Festterminrestriktionen bei der Projektplanung und -steuerung

Zusammenfassung In der einfachen Netzplantechnik werden Limitierungen durch Festtermine nicht berücksichtigt. Alle denkbaren Arten von Festterminrestriktionen werden in der vorliegenden Arbeit analysiert, ihre Bedingungskonstellationen erarbeitet sowie die Möglichkeiten und Auswirkungen der Berücksichtigung derartiger Festterminrestriktionen für beliebige Ereignisse bei der Projektplanung und -steuerung dargestellt.

---

Summary Project Management is limited by a lot of date-restrictions. In this paper the problems are discussed, which result, if fix-date-restrictions must be taken into consideration. The consequences of fix-date-restrictions for all events of project-planning and -scheduling are delineated.

     

Kinematically complete measurement of the absorption of stopped pions in 3He

The reactions π^?3He → nnp and π^?3He → nd have been measured in a kinematically complete experiment with stopped pions. The results show strong preference for collinear events. About three quarters of all absorption processes occur as quasi-free absorption on np- or pp-pairs with a ratio of R = 10.1 ± 1.5. The remaining quarter shows energy sharing among all three nucleons and is located in the final-state interaction regions. Branching ratios for all observed final states are given.