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Ohne Zusammenfassung     

Total synthesis of a noricumazole A library and evaluation of HCV inhibition

The total synthesis of 16 new ion channel inhibitors derived from noricumazole?A, a secondary metabolite from the myxobacterium Sorangium cellulosum, is reported. Particular focus of library design is put on stereochemical permutations in the central region (C9 and C11), the oxazole moiety and the side chain at C4 of the isochromanone moiety. Noricumazole?A and all new noricumazole derivatives were tested in an assay system with inhibitory effect on the hepatitis?C virus (HCV) life cycle. Most of them are moderate to strong HCV inhibitors (350?nM-6?nM) but also exert pronounced cytotoxicity. In contrast, the thiazole analogue of noricumazole?A is a strong HCV inhibitor with only moderate cytotoxic property. It may become a lead structure with a good therapeutic index (CC(50)/IC(50)) of greater than 10.     

Disposable polyester-toner electrophoresis microchips for DNA analysis

Microchip electrophoresis has become a powerful tool for DNA separation, offering all of the advantages typically associated with miniaturized techniques: high speed, high resolution, ease of automation, and great versatility for both routine and research applications. Various substrate materials have been used to produce microchips for DNA separations, including conventional (glass, silicon, and quartz) and alternative (polymers) platforms. In this study, we perform DNA separation in a simple and low-cost polyester-toner (PeT)-based electrophoresis microchip. PeT devices were fabricated by a direct-printing process using a 600 dpi-resolution laser printer. DNA separations were performed on PeT chip with channels filled with polymer solutions (0.5% m/v hydroxyethylcellulose or hydroxypropylcellulose) at electric fields ranging from 100 to 300 V cm(-1). Separation of DNA fragments between 100 and 1000 bp, with good correlation of the size of DNA fragments and mobility, was achieved in this system. Although the mobility increased with increasing electric field, separations showed the same profile regardless of the electric field. The system provided good separation efficiency (215,000 plates per m for the 500 bp fragment) and the separation was completed in 4 min for 1000 bp fragment ladder. The cost of a given chip is approximately $0.15 and it takes less than 10 minutes to prepare a single device.     

Higgs decay into two photons in a warped extra dimension

A detailed five-dimensional calculation of the Higgs-boson decay into two photons is performed in both the minimal and the custodially protected Randall–Sundrum (RS) model, where the Standard Model (SM) fields propagate in the bulk and the scalar sector lives on or near the IR brane. It is explicitly shown that the $R_\xi $ gauge invariance of the sum of diagrams involving bosonic fields in the SM also applies to the case of these RS scenarios. An exact expression for the $h\rightarrow \gamma \gamma $ amplitude in terms of the five-dimensional (5D) gauge-boson and fermion propagators is presented, which includes the full dependence on the Higgs-boson mass. Closed expressions for the 5D $W$ -boson propagators in the minimal and the custodial RS model are derived, which are valid to all orders in $v^2/M_{\text {KK}}^2$ . In contrast to the fermion case, the result for the bosonic contributions to the $h\rightarrow \gamma \gamma $ amplitude is insensitive to the details of the localization of the Higgs profile on or near the IR brane. The various RS predictions for the rate of the $pp\rightarrow h\rightarrow \gamma \gamma $ process are compared with the latest LHC data, and exclusion regions for the RS model parameters are derived.     

Structure elucidation of BaSi2O2N2 – A host lattice for rare-earth doped luminescent materials in phosphor-converted (pc)-LEDs

BaSi₂O₂N₂ is a promising host lattice for rare-earth doped luminescent materials in phosphor-converted (pc)-LEDs. Applying a combined approach, its orthorhombic average structure (space group Cmcm (no. 63), a = 14.3902(3) Å, b = 5.3433(1) Å, c = 4.83256(7) Å and V = 371.58(2) Å³, Z = 4) has been elucidated by electron diffraction and structure solution from X-ray and neutron powder diffraction data with subsequent Rietveld refinement (wRp = 0.0491 for X-ray data). The structure contains layers of highly condensed SiON₃ tetrahedra with O terminally bound to Si. The Ba²⁺ ions are situated between the layers and are surrounded by a cuboid of O atoms capped by two N atoms. In the structure, there is only one Ba site and one Si site, respectively, which is in accordance with a single sharp ²⁹Si NMR signal observed at ?52.8 ppm typical for SiON₃ tetrahedra in MSi₂O₂N₂ type oxonitridosilicates. Lattice energy calculations support the results of the structure determination.     

Challenge of high polarity and low concentrations in analysis of cytostatics and metabolites in wastewater by hydrophilic interaction chromatography/tandem mass spectrometry

A method for solid phase extraction and HPLC–MS/MS of the cytostatics 5-fluorouracil, cytarabine, and gemcitabine and human metabolites uracil 1-β-d-arabinofuranoside and 2′,2′-difluorodeoxyuridine in wastewater was established. Wastewater samples from a Swiss hospital were analyzed for 5-fluorouracil, gemcitabine and 2′,2′-difluorodeoxyuridine. The limits of quantification were 5.0, 0.9, and 9.0 ng/L and the maximum concentrations detected were 27, 38, and 840 ng/L, respectively. Along with the method development, retention mechanisms on the hydrophilic interaction chromatography (HILIC) stationary phase were studied. Both partitioning and adsorption play a role in the retention on the tested sulfoalkylbetaine modified silica HILIC column material. The contribution of these two processes is changing over the 1.6–40% range water in the mobile phase. Although the specific break point is difficult to determine, adsorption becomes more significant as the fraction of water in the mobile phase decreases below approximately 16%.     

Synthesis of Five‐Porphyrin Nanorings by Using Ferrocene and Corannulene Templates

The smallest and most strained member of a family of π‐conjugated cyclic porphyrin oligomers was synthesized by using pentapyridyl templates based on ferrocene and corannulene. Both templates are effective for directing the synthesis of the butadiyne‐linked cyclic pentamer, despite the fact that the radii of their N5 donor sets are too small by 0.5 Å and 0.9 Å, respectively (from DFT calculations). The five‐porphyrin nanoring exhibits a structured absorption spectrum and its fluorescence extends to 1200 nm, reflecting strong π conjugation and Herzberg–Teller vibronic coupling.     

Insights into the Electronic Structure of a U(IV) Amido and U(V) Imido Complex

Reaction of the N-heterocylic carbene ligand ⁱPrIm (L¹) and lithium bis(trimethylsilyl)amide (TMSA) as a base with UCl₄ resulted in U(IV) and U(V) complexes. Uranium's +V oxidation state in (HL¹)₂[U(V)(TMSI)Cl₅] (TMSI=trimethylsilylimido) ( 2 ) was confirmed by HERFD-XANES measurements. Solid state characterization by SC-XRD and geometry optimisation of [U(IV)(L¹)₂(TMSA)Cl₃] ( 1 ) indicated a silylamido ligand mediated inverse trans influence (ITI). The ITI was examined regarding different metal oxidation states and was compared to transition metal analogues by theoretical calculations.