Technomimetic molecules: synthesis of ruthenium(II) 1,2,3,4,5-penta(p-bromophenyl)cyclopentadienyl hydrotris(indazolyl)borate, an organometallic molecular turnstile

A short route to prepare a ruthenium complex with a pentaphenyl substituted cyclopentadienyl and a hydrotris(indazolyl)borate ligand is described: this complex can be seen as an organometallic molecular turnstile.     

Metal Exchange in the Interprotein ZnII-Binding Site of the Rad50 Hook Domain: Structural Insights into CdII-Induced DNA-Repair Inhibition

Cd^II is a major genotoxic agent that readily displaces Zn^II in a multitude of zinc proteins, abrogates redox homeostasis, and deregulates cellular metalloproteome. To date, this displacement has been described mostly for cysteine(Cys)-rich intraprotein binding sites in certain zinc finger domains and metallothioneins. To visualize how a Zn^II-to-Cd^II swap can affect the target protein's status and thus understand the molecular basis of Cd^II-induced genotoxicity an intermolecular Zn^II-binding site from the crucial DNA repair protein Rad50 and its zinc hook domain were examined. By using a length-varied peptide base, Zn^II-to-Cd^II displacement in Rad50’s hook domain is demonstrated to alter it in a bimodal fashion: 1) Cd^II induces around a two-orders-of-magnitude stabilization effect (log =20.8 vs. log =22.7), which defines an extremely high affinity of a peptide towards a metal ion, and 2) the displacement disrupts the overall assembly of the domain, as shown by NMR spectroscopic and anisotropy decay data. Based on the results, a new model explaining the molecular mechanism of Cd^II genotoxicity that underlines Cd^II’s impact on Rad50’s dimer stability and quaternary structure that could potentially result in abrogation of the major DNA damage response pathway is proposed.     

Transfer of splitness with respect to a fully invariant short exact sequence in abelian categories

Abstract

We study the transfer via functors between abelian categories of the (dual) relative splitness of objects with respect to a fully invariant short exact sequence. We mainly consider fully faithful functors and adjoint pairs of functors. We deduce applications to Grothendieck categories, (graded) module categories and comodule categories.     

Selenium‐Catalyzed C(sp3)H Acyloxylation: Application in the Expedient Synthesis of Isobenzofuranones

Oxidative Se‐catalyzed C(sp³)?H bond acyloxylation has been used to construct a diverse array of isobenzofuranones from simple ortho‐allyl benzoic acid derivatives. The synthetic procedure employs mild reaction conditions and gives high chemoselectivity enabled by an inexpensive organodiselane catalyst. The presented approach offers a new synthetic pathway toward the core structures of phthalide natural products.     

Reaction and transport effects in the heterogeneous systems for lean gas purification

Sorption of hydrogen chloride gas by active soda and that of hydrogen sulfide gas by calcium oxide are explored by experiment as promising means of removing these detrimental contaminants from fuel gas: active Na₂CO₃ was prepared by the calcination of commercial NaHCO₃ at 200 °C; reactive CaO was formed by decomposing a fine-grained, high-calcium limestone at 830 °C. Techniques with a differential reactor were employed to explore the rate of reaction of HCl with Na₂CO₃ at 500 °C and that of H₂S with CaO at 800 °C. Time-resolved data on the sorbents’ conversion were collected as a function of mean particle size in the range between 0.285 and 1.12 mm. The surface reaction constants, deduced via the tractable model from the initial reaction rates of the two reactions, slightly increase with the increasing particle size. The proposed correlations enable to interpolate or cautiously extrapolate to other isotropic, irregularly shaped solids. The effective diffusivities educed by means of the model from the experimental curves decrease significantly with the increasing conversion and are affected by the particle size in both sorptions. The developed reaction rate equations can conveniently be applied to the design and simulation of the deep dechloridization and the bulk desulfurization of hot producer gas.     

Estimation des projecteurs de De Rham Hodge de certaines variétés riemaniennes non compactes

On montre des estimées pour le projecteur de De Rham–Hodge. We prove estimates for the De Rham–Hodge L^p projectors. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A Bragg grating embedded in a slab waveguide fabricated by the implantation of high-energy light ions in KLTN substrate

Electro-optically tunable transmission grating was imprinted in potassium lithium tantalate niobate by irreversible spatial patterning of the dielectric constant. While embedded into waveguided architecture, it provides a reliable and versatile building block for opto-electronic circuitry, capable of both active switching and multiplexing. Realization of such a block is critical for the fabrication of integrated photonic circuits in electro-optic substrates by means of Refractive Index Engineering by fast ion implantation.