PHOTOCHEMISTRY OF REDUCED LUMIFLAVIN IN ITS ACIDIC FORM

Abstract— The photooxidation of reduced lumiflavin in its acidic form, LfH 3 ⁺, takes place in two consecutive steps. Upon illumination of LfH 3 ⁺ in its absorption band at 313 nm the semiquinone, LfH 3 ⁺, is formed. Two LfH 2 ⁺ ions are consumed for every LfH 2 ⁺ formed. Illumination of the semiquinone in its absorption band at 495 nm causes further oxidation so that the oxidized LfH⁺ ion is formed. In this reaction one LfH 3 ⁺ ion is photolyzed for every LfH⁺ formed. In addition, a hydrogen atom is released in the photooxidation of LfH 2 ⁺. Mechanisms for the two photoreactions are proposed.     

Ein fünffach koordinierter ionischer zirkonium(IV)-komplex mit der (π-C5H5)2ZrIV-Baueinheit: [(π-C5H5)2Zr(H2O)3]2+(CF3SO3−)2·THF

The ionic complex [(π-C₅H₅)₂Zr(H₂O)₃]²⁺(CF₃SO₃^?)₂·THF, which corresponds to the 18-electron rule, is formed in the reaction of (π-C₅H₅)₂Zr(CF₃SO₃)₂(THF) with H₂O in tetrahydrofuran. It crystallizes in the hexagonal space group P6₃ with Z = 6 and unit cell dimensions at ? 100°C of a 21.945(5) and c 8.711(3) Å. The geometry of the (π-C₅H₅)₂Zr moiety (length of the vectors between Zr and the C₅ ring centroids: 2.210 and 2.193 Å; angle between these vectors: 129.0°; angle between the C₅ ring normals: 128.3°) agrees with that of neutral, four-coordinate (π-C₅H₅)₂ZrX₂ compounds. The three H₂O ligands lie in the plane that bisects the angle between the C₅ ring planes. The ZrO distances are 2.239(7), 2.195(7), and 2.261(7) Å. The CF₃SO₃^? anions and the THF molecule of crystallization are packed around the complex cation in such a way that their oxygen atoms point towards the H₂O ligands. The CF₃ sides of the anion, on the other hand, are clustered together so as to produce hydrophobic domains in the crystal structure.     

Optical sectioning in wide-field microscopy obtained by dynamic structured light illumination and detection based on a smart pixel detector array

Optical sectioning in wide-field microscopy is achieved by illumination of the object with a continuously moving single-spatial-frequency pattern and detecting the image with a smart pixel detector array. This detector performs an on-chip electronic signal processing that extracts the optically sectioned image. The optically sectioned image is directly observed in real time without any additional postprocessing.     

Free-space fluorescence molecular tomography utilizing 360 degrees geometry projections

Fluorescence tomography of diffuse media can yield optimal three-dimensional imaging when multiple projections over 360 degrees geometries are captured, compared with limited projection angle systems such as implementations in the slab geometry. We demonstrate how it is possible to perform noncontact, 360 degrees projection fluorescence tomography of mice using CCD-camera-based detection in free space, i.e., in the absence of matching fluids. This approach achieves high spatial sampling of photons propagating through tissue and yields a superior information content data set compared with fiber-based 360 degrees implementations. Reconstruction feasibility using 36 projections in 10 degrees steps is demonstrated in mice.     

Reiter’s condition for amenable hypergroups

We study modifications of Reiter’s condition (P _r ) which are generated by certain power and root procedures. In that way we can illustrate the difference between the (P ₁)- and the (P ₂)-property. Furthermore we present equivalent conditions to (P ₂). In order to have examples we discuss the results for polynomial hypergroups.     

Bis-μ-hydroxo-bis(π-cyclopentadienyldinitratozirkonium-(IV))tetrahydrofuran(12), ein zweikerniger organozirkonium(IV)-komplex mit siebenfach koordinierten metallzentren

Cp₂ZrCl₂ reacts with nitric acid in CHCl₃ to yield a dinuclear, doubly OH-bridged complex which can be isolated together with tetrahydrofuran of crystallization: [π-C₅H₅Zr(NO₃)₂(μ-OH)]₂ · 2THF (B). The crystal data of B are as follows: space group P2₁/c, a 8.825(2), b 12.137(3), c 13.018(2) Å, β 97.61(2)°. The unit cell contains two dinuclear centrosymmetric metal complexes and four molecules of tetrahydrofuran of crystallization. The Zr atom has a pentagonal-bipyramidal coordination geometry with the Cp group occupying an axial position, two chelating NO₃ ligands and one OH bridging group in the equatorial plane, and one OH group in the other axial position.     

Dark-field optical coherence microscopy

Dark-field illumination is known to enhance scattering contrast in optical microscopy. We combined this concept with Fourier domain optical coherence microscopy (OCM). The detection and illumination paths are decoupled, and only the scattered light originating from the sample generates the tomogram signal, whereas any specular reflection is highly suppressed. We analyze and discuss this dark-field OCM concept and present its superior imaging quality on live cell samples.