Intramolecular photoreactions of 6-(ω-alkenyl)-4-methoxy-2-pyrones

6-(ω-Alkenyl)-2-pyrones 3a-c and 8a, b were prepared and the photochemical reactions were investigated. Photosensitized reactions of 3b, c gave intramolecular [2+2]-cycloadducts 11b, c as tricyclic lactones, site-and regio-specifically. They are not frontier-orbital-controlled adducts. On the other hand, 3a, 8a, b afforded cyclobutenecarboxylic acids, 10a, 14a, b , respectively. The end-ester group at the side-chain is thought not to be effective for the intramolecular phptoaddition.     

Association behavior of a nitrilotriacetic-acid-modified dye in a poly(vinyl alcohol) film containing Ni(II)-adsorbed gold nanoparticles.

The association behavior of the dyes 5(6)-carboxyfluorescein and nitrilotriacetic acid (NTA)-modified 5(6)-carboxyfluorescein (F-NTA) in a poly(vinyl alcohol) (PVA) film and in a PVA film containing metal nanoparticles is investigated. Well-dispersed gold nanoparticles (AuNps) and Ni(II)-adsorbed AuNps are formed in the PVA film using in situ photochemical fabrication method. 5(6)-carboxyfluorescein and F-NTA are doped into the films. The F-NTA forms an H-aggregate in the PVA film containing Ni(II)-adsorbed AuNps. It is suggested that the interaction between NTA and Ni(II) adsorbed on the AuNps promotes the formation of the H-aggregate.     

A novel type secoiridoid glucoside,hydrangenoside a from Hydrangea macrophylla

Hydrangenoside A, isolated along with its three congeners from Hydrangea macrophylla, was proved to have a novel type of structure which is thought to be biosynthesized through an aldol-type condensation of secologanin with a unit formed by the shikimate-malonate route followed by decarboxylation.     

Autoxidized phospholipids in hexane: nano-self-assemblies studied by synchrotron small-angle X-ray scattering

Synchrotron small-angle X-ray scattering (SAXS) was used to analyze the structure of self-assembled autoxidized phospholipids in a very dilute solution of hexane. In addition, it was used to build a self-consistent model of the aggregates, taking into account their inner heterogeneities and polydispersity. The scattering intensity from a dilute mixture of different types of noninteracting components of the phospholipid system was represented as a linear combination of partial intensities from the components weighted by their volume fractions. Applying this approach the final model of the system was described as a mixture of polydisperse reverse micelles and aggregates with spherical and cylindrical shapes. Spherical aggregates were represented as hollow spheres with inner radius 0.7 nm (occupied by water or hexane) and outer radius 1.5 nm. Geometrical parameters of the aggregates did not change much during the oxidation process, while the ratio of reverse micelles and aggregates in solution varied. The amount of the reverse micelles increased from very low to about 80%, whereas the content of other aggregates constantly reduced. The analysis performed in this study helps one to better understand the processes of phospholipid oxidation, which may occur in biological membranes.     

Error bounds for computed eigenvalues and eigenvectors

Summary On the basis of an existence theorem for solutions of nonlinear systems, a method is given for finding rigorous error bounds for computed eigenvalues and eigenvectors of real matrices. It does not require the usual assumption that the true eigenvectors span the whole space. Further, a priori error estimates for eigenpairs corrected by an iterative method are given. Finally the results are illustrated with numerical examples.Dedicated to Professor Yoshikazu Nakai on his sixtieth birthday     

Tumor cell detection method using complement-mediated cytolytic reaction and imaging sensor system

A novel tumor-detection system consisting of complementmediated cytolytic reaction and an image processing system was developed for the simple and rapid determination of tumor cells. The present system consists of a CCD image sensor, image memory board, personal computer, and microscope. When monoclonal antibody 3C4, which is specific to the guinea pig hepatoma L-10, was added to cell suspension, only L-10 cytolysis occurred. Cytolysis caused a decrease in brightness of the cells observed by phase-contrast microscopy. The phase contrast image of the cells before cytolysis was converted to a digitalized signal and stored in computer memory. After cytolysis, a brightness threshold above that of lysed cells was subtracted from the digitalized signal and compared to the signal stored before reaction. L-10 cells in mixed cell suspension were determined specifically by the system. Measurement time was only 2 sec and overall time, including reaction time, was approximately 30 min. Since this method does not require a cell washing process, automation of the whole system is possible.     

A study on the effect of the source line profile in atomic magneto-optical rotation spectroscopy (AMORS), using a Zeeman-shifted hollow cathode lamp

Summary Using a magnetized hollow cathode lamp as a Zeeman-shifted light source, the effects of the source line profile on the intensity of rotatory radiation and the calibration curve were studied for AMORS (atomic magneto-optical rotation spectroscopy). With the alteration of the source line profile, an increase in the intensity of rotatory radiation by about max. 40% was found. The rollover of the calibration curve could be avoided by selecting the strengths of the magnetic fields applied to the atomizer and the hollow cathode lamp.

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Untersuchung der Wirkung des Linienprofils der Lichtquelle in der magneto-optischen Atomrotations-Spektroskopie (AMORS) mit Hilfe einer Hohlkathodenlampe mit Zeeman-Verschiebung

Zusammenfassung Mit Hilfe einer magnetisierten Hohlkathodenlampe als Lichtquelle mit Zeeman-Verschiebung wurden die Wirkungen des Linienprofils der Lichtquelle auf die Intensität der Rotationsstrahlung und auf die Eichkurve untersucht. Mit Änderung des Linienprofils ergab sich eine Intensitätssteigerung der Rotationsstrahlung bis zu 40%. Abweichungen der Eichkurve konnten durch geeignete Wahl der magnetischen Feldstärken am Atomizer und der Hohlkathodenlampe vermieden werden.

     

Diels-alder reactions of cyclohexadienes derived from decarboxylation of photo[4 + 2]cycloadducts between 4,6-dimethyl-2-pyrone and cyclic olefins

Labile photo [4 + 2] adducts between 4,6-dimethyl-2-pyrone and cyclic olefins reacted with second olefins to give cross adducts, and with acetylenes to afford both bis-adducts and benzene derivatives with the concurrent decarboxylation, respectively. The reaction mechanism of the latter was considered.