Phomactin H, a novel diterpene from an unidentified marine-derived fungus

Phomactin H (1), a diterpene has been isolated from cultures of an unidentified marine-derived fungus. The structure and relative stereochemistry of phomactin H (1) was determined by X-ray diffraction analysis. Phomactin H (1), having an oxepane moiety, is a new phomactin with a novel skeleton.     

Interstitial superstructures in the TaD system

Ordered deuterium arrangements and order-disorder transformations of the tantalum deuterides in the range TaD_0.50TaD_0.78 have been studied by neutron diffraction and calorimetry at temperatures between ?170 and 120°C. In addition to the disordered phase (α), three ordered phases based on the superstructures Ta₂D_1+x (β₁), Ta₄D₃, (γ), and TaD (δ) are clarified. The Ta₂D_1+x structure is a nonstoichiometric from of the Ta₂D superstructure over the rangex < 0.5. The γ-phase is formed below ?70°C near Ta₄D₃, and transforms into theβ₁and δ-phases, respectively, in the hypo and hyperstoichiometric compositions. The δ-phase that exists beyond TaD_0.75 changes to the disordered α-phase around 100°C.     

Measurements of B decays to two kaons

We report measurements of B meson decays to two kaons using 253 fb(-1) of data collected with the Belle detector at the KEKB energy-asymmetric e+ e- collider. We find evidence for signals in B+ --> K0 K+ and B0 --> K0 K0 with significances of 3.0sigma and 3.5sigma, respectively. (Charge-conjugate modes are included.) The corresponding branching fractions are measured to be [symbol: see text](B+ --> K0 K+) = (1.0 +/- 0.4 +/- 0.1) x 10(-6) and [symbol: see text](B0 --> K0 K0) = (0.8 +/- 0.3 +/- 0.1) x 10(-6). These decay modes are examples of hadronic bd transitions. No signal is observed in the decay B0 --> K+ K-, and we set an upper limit of 3.7 x 10(-7) at 90% confidence level.     

Influence of internal structure on kinetics of drug release from wax matrix tablets

To examine the influence of the internal structure of a wax matrix tablet on in vitro drug release, the release rates of several tablets consisting of various proportions of drug and wax were compared with the water penetration rates from the compressed and lateral surfaces of the tablets. The penetration rates from the lateral surface were found to be much faster than those from the compressed surface in all cases. A theoretical equation involving a two-dissolving-direction was derived on the basis of the boundary retreating concept. The retreating rate constants deduced from the dissolution results were well coincident with the values directly determined by the needle penetration method, suggesting good applicability of the proposed equation. The results suggest that the tortuosity of the water channels created in a tablet during dissolution is generally smaller in the horizontal direction than that in the vertical direction. This would be caused by the drug particles or granules being elongated in the horizontal direction by compression.     

Temperature-sensitive hairy particles prepared by living radical graft polymerization

Four types of temperature-sensitive hairy particles were prepared by living radical graft polymerization using a photoiniferter. The hairs were poly(N-isopropylacrylamide) (N), poly(N-isopropylacrylamide)ran-poly(acrylic acid) (NA), and diblock copolymers composed of N and NA. The block copolymer was attached to the particle in different modes, that is, one has a N-block inner and a NA-block outer but the other has the inverse arrangement. The acrylic acid content in NA was adjusted to be only 1%, but NA had a higher transition temperature by 5 degrees C than N in a neutral aqueous solution. The sequence of blocks attached onto the particle was the key factor to control the temperature responsiveness of the particle. The hairy particles exhibited a two-step transition with increasing temperature under certain conditions. The hairy particle also responded to the pH and ionic strength. Some unique behaviors of the hairy particles were studied in detail in terms of electrophoretic mobility and adsorption of dye molecules as well as swelling/deswelling.     

Photonic crystals for the visible range fabricated by autocloning technique and their application

We fabricate photonic crystals for the visible range by the autocloning technique, in which multilayers are stacked by an appropriate combination of sputter deposition and sputter etching. TiO₂/SiO₂ and Ta₂O₅/SiO₂ are chosen as materials since they are transparent in the range and give a high contrast of refractive indices. The fabrication technique has flexibility regarding materials and size and is very reliable and reproducible even if the pitch is less than 0.2 m. We also study the application of photonic crystals to birefringent elements such as waveplates and polarization selective gratings and experimentally verify that they are useful for optical pick-up systems.     

Observation of Cabibbo suppressed B --> D(*)K- decays at Belle

We report observations of the Cabibbo suppressed decays B-->D((*))K- using a 10.4 fb(-1) data sample accumulated at the Upsilon(4S) resonance with the Belle detector at the KEKB e(+)e(-) storage ring. We find that the ratios of Cabibbo suppressed to Cabibbo favored branching fractions are B(B--->D0K-)/B(B--->D0pi(-)) = 0.079+/-0.009+/-0.006, B(B(0)-->D+K-)/B(B(0)-->D+pi(-)) = 0.068+/-0.015+/-0.007, B(B--->D(*0)K-)/B(B--->D(*0)pi(-)) = 0.078+/-0.019+/-0.009, and B(B(0)-->D(*+)K-)/B(B(0)-->D(*+)pi(-)) = 0.074+/-0.015+/-0.006. These are the first observations of the B-->D+K-, D(*0)K-, and D(*+)K- decay processes.     

Self-assembly of poly(N-isopropylacrylamide)-carrying microspheres into two-dimensional colloidal arrays

Droplets containing polymer particles were deposited on a substrate. Poly(N-isopropylacrylamide) (PNIPAM) hydrogel and particles with PNIPAM graft chains on the surface self-assembled into a two-dimensional (2-D) superlattice when their dilute dispersions were dried on substrates. The capillary force between the particles induced ordered array formation during water evaporation. The presence of a PNIPAM layer on the particle surface gave the particles steric stability during ordered array formation. By grafting PNIPAM chains on particle surfaces by living radical polymerization, we successfully controlled the structural patterns of the colloidal arrays. These, controllable, 2-D colloidal arrays were generated on various substrates upon air-drying.