Monoprotonated Sapphyrin–Pertechnetate Anion Interactions in Aqueous Media

The addition of aqueous pH 7 solutions of 7.2×10^-3?M pertechnetate to dilute aqueous 2.5% MeOH solutions containing a water-solubilized sapphyrin, 3,12,13,22-tetraethyl-8,17-bis[bis(hydroxyethyl)-amino)carbonylethyl]-2,7,18,23-tetramethylsapphyrin (1), gives rise to spectroscopic changes in the UV–Vis spectrum of 1 that are consistent with anion-binding and sapphyrin deaggregation. The spectroscopic changes induced by pertechnetate were found to differ dramatically from those induced by the addition of either pure water or dilute nitric acid; however, they were found to parallel those seen when sodium phosphate was added to solutions of 1 under analogous experimental conditions. Fits of the spectroscopic titration data to a 1:1 binding profile revealed that the effective K describing the interaction of pertechnetate anion with 1 was ca. 3900±300?M^-1; this value compares to the effective K of 23000±3000?M^-1 that describes the corresponding interaction of sodium phosphate with 1.     

A Substrate-Inspired Probe Monitors Translocation,Activation, and Subcellular Targeting of Bacterial Type III Effector Protease AvrPphB

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Highlights? Bacterial papain-like protease AvrPphB cleaves kinases in host plant cell ? Activity-based probe for AvrPphB inspired on its unique substrate specificity ? Secretion of ProAvrPphB through narrow type III pilus requires prodomain ? Prodomain removal is essential to trigger cell death in resistant plants     

Heterologous Expression and Engineering Studies of Labyrinthopeptins,Class III Lantibiotics from Actinomadura namibiensis

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Highlights? Heterologous expression of a class III lantibiotic gene cluster in S. lividans and S. albus ? Leader peptide adaptation for proteolytic processing in the S. lividans host ? Development of an efficient expression system for production of labyrinthopeptin variants ? Identification of variable regions in labyrinthopeptins and generation of analogs     

Influence of the local absorber layer thickness on the performance of ZnO nanorod solar cells

The local absorber layer thickness (d_local) of solar cells with extremely thin absorber was changed between 10 nm and 70 nm. As a model system, ZnO nanorod arrays (electron conductor) with fixed internal surface area coated with In₂S₃ (absorber) and impregnated with CuSCN (transparent hole conductor) were applied. The performance of the small area solar cells depended critically on d_local. The highest short circuit current density was reached for the lowest d_local. In contrast, the highest open circuit voltage was obtained for the highest d_local. A maximum energy conversion efficiency of 3.4% at AM1.5 was achieved. Limiting factors are discussed.(© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Stereoselective synthesis of substituted N-heterocycles via sequential cross metathesis—reductive cyclization

A diastereoselective synthesis of substituted mono- and bicyclic-piperidine and pyrrolidine derivatives is presented, employing a highly selective cross metathesis (CM) reaction followed by a domino reduction-cyclization process.     

Trapped modes for periodic structures in waveguides

The Laplace operator is considered for waveguides perturbed by a periodic structure consisting of N congruent obstacles spanning the waveguide. Neumann boundary conditions are imposed on the periodic structure, and either Neumann or Dirichlet conditions on the guide walls. It is proven that there are at least N (resp. N‐1) trapped modes in the Neumann case (resp. Dirichlet case) under fairly general hypotheses, including the special case where the obstacles consist of line segments placed parallel to the waveguide walls. Copyright © 2004 John Wiley & Sons, Ltd.     

Semi-Quantitative Determination of Free Cyclic and Linear Polytetrahydrofurane in Coatings Using Critical Chromatography

Summary Liquid chromatography at critical conditions (LCCC) is being used more frequently, especially for the determination of cyclic structures in a matrix of the parent linear molecules, analyses that cannot be performed easily by other techniques. In practice, analyses are often more complex than separating the linear from the cyclic structures, e.g. in the determination of low concentrations of free (linear and cyclic) polyols like polytetrahydrofurane (pTHF) in functional polymers and coatings. To this end different chromatographic phase systems at the critical conditions for the polyols were investigated to obtain the maximum amount of information. The identification of different oligomeric series was performed by means of an on-line coupling of LCCC with atmospheric pressure chemical ionization – mass spectrometry (APCI-MS). Mass summated chromatograms were introduced to improve the signal to noise ratio of specific oligomeric series. MS cannot be used for quantitative purposes here; therefore the evaporative light scattering detector (ELSD) and the refractive index (RI) detectors were evaluated for routine analyses. Specific tailing problems observed with a drift tube in the ELSD are discussed. Two LCCC systems (reversed phase and normal phase) were compared for best selectivityPresented at: International Symposium on Separation and Characterization of Natural and Synthetic Macromolecules, Amsterdam, The Netherlands, February 5–7, 2003