An improved single-mode Y-branch design for cascaded 1:2 splitters

The power splitting ratio of Y-branches based on step index waveguides has been calculated using three-dimensional (3-D) finite-difference beam propagation method (FD-BPM). Due to interference of the guided mode with quasiguided modes generated at distortions of the waveguide the splitting ratio depends on the wavelength and design parameters of the Y-branch. The simulations show how variations of the splitting ratio can be minimized using a mode-filter in the input section without significant increase of losses or component size     

A Modular System for the Rapid Comparison of Different Membrane Anchors for Surface Display on Escherichia coli

Comparison of different membrane anchor motifs for the surface display of a protein of interest (passenger) is crucial for achieving the best possible performance. However, generating genetic fusions of the passenger to various membrane anchors is time-consuming. We herein employ a recently developed modular display system, in which the membrane anchor and the passenger are expressed separately and assembled in situ via SpyCatcher and SpyTag interaction, to readily combine a model passenger cytochrome P450 BM3 (BM3) with four different membrane anchors (Lpp-OmpA, PgsA, INP and AIDA-I). This approach has the significant advantage that passengers and membrane anchors can be freely combined in a modular fashion without the need to generate direct genetic fusion constructs in each case. We demonstrate that the membrane anchors impact not only cell growth and membrane integrity, but also the BM3 surface display capacity and whole-cell biocatalytic activity. The previously used Lpp-OmpA as well as PgsA were found to be efficient for the display of BM3 via SpyCatcher/SpyTag interaction. Our strategy can be transferred to other user-defined anchor and passenger combinations and could thus be used for acceleration and improvement of various applications involving cell surface display.     

Regioselective Cobalt‐Catalysed Hydrovinylation for the Synthesis of Non‐Conjugated Enones and 1,4‐Diketones

The highly regioselective cobalt‐catalysed 1,4‐hydrovinylation of terminal alkenes with 2‐trimethylsilyloxy‐1,3‐butadiene generates in a stereospecific fashion unsaturated E‐configured silyl enol ether intermediates that are suitable for diastereoselective Mukaiyama‐aldol reactions with bulky aliphatic aldehydes. The acidic hydrolysis of the enol ethers to γ,δ‐unsaturated ketones followed by ozonolysis can be used for the synthesis of various 1,4‐diketones and polycarbonyl derivatives. The 1,4‐diketones and polycarbonyl derivatives were successfully tested for the synthesis of some mono‐ and bis‐pyrrole derivatives. The γ,δ‐unsaturated ketones are useful building blocks (e.g., in natural product synthesis) and can be generated in a one‐pot procedure.     

Heterogeneous and homogeneous reactions of pyrolysis vapors from pine wood

To maximize oil yields in the fast pyrolysis of biomass it is generally accepted that vapors need to be rapidly quenched. The influence of the heterogeneous and homogeneous vapor‐phase reactions on yields and oil composition were studied using a fluidized‐bed reactor. Even high concentrations of mineral low char (till 55 vol %) appeared not to be catalytically active. However, the presence of minerals, either in biomass or added, does influence the yields, especially by the occurrence of vapor‐phase charring/polymerization reactions. Contradictory, in the absence of minerals, homogeneous vapor‐phase cracking reactions were dominant over polymerization/charring reactions (400–550°C, 1–15 s). With increasing vapor residence time, the oil yield reached an asymptotic value, which decreased with temperature. At a vapor temperature of 400°C no decrease in oil yield was observed, but dedicated analysis showed that homogeneous vapor to vapor reactions had occurred. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Synthese und Solvatochromie einiger Azofarbstoffe mit Ferrocen als Elektronendonor-Gruppe für die optische Datenspeicherung

Synthesis and Solvatochromism of Some Azo Dyes with Ferrocene as Electron Donor Group for Optical Data Recording We synthesized the arylazo compounds 3a-c , 5a , b , 5d , 5f , 6b , 6d , 6f , 7–9 containing ferrocene as electron donor group and different electron acceptors or donors in order to tune the absorption wavelength. Compounds 5f , 6f , 8 , 9 were incorporated as side chains in liquid crystalline polymers. As holographic experiments showed these materials are not superior to polymers containing arylazochromophores without the ferrocene moiety like compounds 10 , 11 . In addition, the solvatochromism of the ferrocene azo compounds has been measured as a first test of their first order NLO activity. Only compound 9 showed remarkable values.