Über die Lichteinwirkung auf Stoffe vom Typus der Furo-cumarine

Ohne Zusammenfassung     

Über das Ononin II

Ohne Zusammenfassung     

Microanatomical and biochemical origins of normal and precancerous cervical autofluorescence using laser-scanning fluorescence confocal microscopy

Clinical studies have shown that in vivo fluorescence spectroscopy can improve the diagnosis of cervical precancer. Recent work suggests that epithelial fluorescence increases, whereas stromal fluorescence decreases, with precancer. However, the microanatomic and biochemical sources of fluorescence in living cervical tissue have not yet been established. This study aims to characterize the origins of living normal and precancerous cervical fluorescence at microscopic levels using laser-scanning fluorescence confocal microscopy. Ten pairs of colposcopically normal and abnormal biopsies were obtained; transverse, 200 microm thick, short-term tissue cultures were prepared and imaged when viable with UV (351-364 nm) and 488 nm excitation before and after addition of the vital dye, Mitotracker Orange. In normal epithelium basal epithelial cells showed cytoplasmic fluorescence; parabasal, intermediate and superficial cells showed fluorescence only at the periphery of the cell. In low-grade precancers cytoplasmic fluorescence was visible in the bottom one-third of the epithelium; in high-grade precancers cytoplasmic fluorescence was visible throughout the lower two-thirds of the epithelium. Cytoplasmic fluorescence was colocalized with the MitoTracker probe and is attributed to mitochondrial reduced form of nicotinamide adenine dinucleotide at UV excitation and mitochondrial flavin adenine dinucleotide at 488 nm excitation. Stromal fluorescence originated from matrix fibers; with the development of precancer the density and fluorescence intensity of matrix fibers decrease. Autofluorescence properties of precancerous cervix reflect an increased number of metabolically active mitochondria in epithelial cells and a reduced stromal fluorescence, which can be an indicator for altered communication between precancerous epithelium and stroma. These changes can explain differences in in vivo fluorescence spectra of normal and precancerous cervical tissue.     

Spin coating process of sol-gel silicate films deposition: Effect of spin speed and processing temperature

The effect of two factors having the most important influence on spin coating process of sol-gel films: the spin speed and the temperature (of the substrate and the applied solution) during film deposition is discussed. It is shown, that film thickness and thickness uniformity are determined by centrifugal driving force dynamics, viscous polymer rheology, solvent evaporation dynamics, and film porous microstructure.     

Orthoamides and iminium salts LXXII: N,N,N',N',N',N',N',N'-octamethyl-(but-2-yne)-bis(amidinium) tetrafluoroborate: the first bis-amidinium salt of acetylenedicarboxyclic acid. A new superelectrophile?

A method for the preparation of the first acetylenedicarboxamidinium salt from a bis-orthoamide derivative of acetylenedicarboxyclic acid has been established. The salt reacted with cyclopentadiene and furan at room temperature to give bicyclic [4+2]-cycloaddition products. The solid compounds were characterized by solution NMR spectroscopy and by single-crystal X-ray diffraction. Quantum-chemical calculations of the isolated N,N,N',N',N',N',N',N'-octamethyl-acetylene-bis(carboxamidinium) ion showed very good agreement with the spectroscopic and diffraction data.     

Synthesis and characterization of nonsymmetric cyclopentene-based dithienylethenes

Nonsymmetric cyclopentene-based dithienylethenes, containing both thienyl and benzothienyl units, have been synthesized for the first time, employing intramolecular McMurry reaction as a key transformation to target compounds 10 and 16. Photochromic properties of these compounds were examined in toluene and acetonitrile solutions, PMMA layers, solid films, and crystal phase. To explain an unprecedented single-crystalline photochromism phenomena of 10, X-ray crystallographic analysis was performed, revealing a significant influence of strong S···S interatomic interactions on the intramolecular distance between two photochemical reaction centers in the molecule. Compound 16 could be further synthetically modified in a step-by-step manner, thus serving as potential key intermediate to various complex bifunctional photochromic molecules.     

New 3-Cyano-1,2λ 3 -Thiaphosphacyclanes and Their Complexing Properties

Reduction of both individual diastereomers of 2-oxo-1,2-thiaphosphacyclanes by HSiCl 3 proceeds with retention of cyclic structure, cyano-group, and stereochemical configuration.     

Efficient Synthetic Approach to Fluorescent Oxazole-4-carboxylate Derivatives

In our attempt to synthesize a halogenated analog of green fluorescent protein (GFP) chromophore, we discovered a simple and efficient synthetic strategy to the derivatives of oxazole-4-carboxylic acid substituted at positions 2 and 5. The method allows for introduction of different aryl substituents at the position 5, aryl or alkyl substituents at position 2 of oxazole, and gives access not only to free carboxyl at position 4, but also to a range of its amide derivatives. The advantages of the synthetic strategy presented are availability of precursors, good yields, and avoiding palladium coupling and metalation procedures. The synthesized compounds fluoresce in visible region with quantum yields up to 0.82. We believe that 5-aryl-4-carboxyoxazole is a promising core for creation of new fluorescent dyes.

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