Synthesis and antifungal activity of novel 14-membered benzomacrolides, as galbonolide analogues

Asymmetric total synthesis of benzene analogues of galbonolide, a 14-membered antifungal macrolide, possessing a benzene ring instead of a conjugated diene structure, was achieved starting from chiral 1-aryl-1-propanol obtained by enzyme-catalyzed kinetic resolution with high enantioselectivity. Representatively, a method for the introduction of a methylthio and chloride function at the vinyl position was also established. The resulting analogues unfortunately exhibited very little antifungal potency in comparison with galbonolide A.     

Oxygen-sensing mechanism of HemAT from Bacillus subtilis: a resonance Raman spectroscopic study

Resonance Raman (RR) evidence for structural linkage between the distal side of heme pocket and the signaling domain of an oxygen sensing hemoprotein, HemAT-Bs, is reported. The band-fitting analyses of the RR spectra in the Fe-O2 stretching (nuFe-O2) region revealed the presence of three conformers with nuFe-O2 at 554, 566, and 572 cm-1, which reflect different H-bond strengths on the bound O2 molecule. While recent X-ray analysis for CN--bound HemAT-Bs suggested the importance of Thr95 and Tyr70, the species with the strongest H-bond (554 cm-1) was deleted in the T95A mutant and also by removal of the linker and signal domains; however, the Y70F mutant maintained the same three conformers. A scheme for specific O2 sensing and signaling mechanism is discussed.     

Diastereoselective [2 + 2] photocycloaddition of stilbene to chiral fumarate. Direct versus charge-transfer excitation

The selective excitation of the charge-transfer (CT) complex and the direct excitation of the substrate gave distinctly different product ratios and diastereomeric excesses (de's), as well as their temperature dependencies, in [2 + 2] photocycloaddition of (E)-stilbene to bis((R)-1-methylpropyl) fumarate, clearly demonstrating that the excited CT complex and the conventional exciplex differ in structure and reactivity. This conclusion is supported by the contrasting fluorescence behavior exhibited by the relevant excited species, particularly at low temperatures.     

Modified micro-space using self-organized nanoparticles for reduction of methylene blue

By using silica layers bound to the surface of the inner wall of the microchannel via a self-assembly technique which relies on capillary forces to organize the colloids, TiO2 particles were attached to the inner surface of a microcapillary. The reduction rate of methylene blue increased by more than 150 times in the SiO2/TiO2 modified micro-space compared to that in a batch system.     

Asymmetric total synthesis of pseurotin A

The asymmetric total syntheses of pseurotin A and 8-O-demethylpseurotin A have been accomplished. Key reactions are a NaH-promoted intramolecular cyclization of an alkynylamide to form a gamma-lactam, an aldol reaction of a benzylidene-substituted ketone, and the late-stage introduction of the benzoyl group by a selective oxidation of a benzylidene moiety with dimethyldioxirane (DMD). [reaction: see text]     

Syntheses of vinyl polymers with pendant porphyrin dimers and their catalytic effects on photoreductions

Vinyl copolymers with pendant porphyrin dimers were synthesized first by the dimerizations of chlorophyll-α and protoporphyrin IX via the ethylenebisamide linkage, then by copolymerization of the vinylbenzyl esters of the resulting dimers with N-vinylpyrrolidone or the esterification reaction of the dimers with chloromethylstyrene copolymers. Dimer-pendant copolymers with vinyl pyrrolidone catalyzed photoredox systems in aqueous solutions more efficiently than the corresponding monomer analogs, presumably because of the interactions exerted between the two combined porphyrin rings, which are manifested in the hypochromic effect in absorption spectra. The effect of the central Mg atom in the protoporphyrin IX ring was also considerable.     

Sharpness Matching between Digital Image Display Devices

A method is presented for matching apparent sharpness between digital image display devices with different characteristics. The sharpness is most precisely described by the point spread function (PSF) as opposed to dot density such as DPI (dot per inch). The difference between devices is expressed as difference between transfer functions obtained from the PSFs. In the presented method, spatial frequency filtering for one digital image is carried out where the ratio of the transfer functions or its modified version is used as filter. The modification is introduced as a clipping operation to reduce excessive enhancement when the ratio of the transfer functions has a high pass characteristic with large gain. Through computer simulation including a subjective evaluation experiment and numerical evaluation, the effectiveness of filtering operation for sharpness matching is demonstrated.     

Development of optical pickup for mini disc drives

In order to miniaturize optical disc drives, it is important to miniaturize and thin the optical pickup. We have developed two new optical parts: the hologram laser and the actuator. By optimizing the hologram pattern of the hologram laser, optical path length is shortened. The frequency characteristics of the actuator have been stabilized by improving the damping characteristics. Thus, we have developed a compact optical pickup for Mini Disc drives, and the pickup shows high performance when it reads out an optical disc.     

A note on the rate of convergence of Schauder decomposition

An improved rate of convergence of Schauder decomposition in the Sobolev space W_pⁿ is established. This extends the result previously obtained in J. Math. Anal. Appl., 102 (1) (1984) 203–210.