Brillouin lasing in a single-mode tellurite fiber

We demonstrate Brillouin lasing in a single-mode TeO(2)-Bi(2)O(3)-ZnO-Na(2)O tellurite fiber. A peak value of Brillouin gain coefficients of 1.6989 x 10(-10) m/W is measured on the basis of gain characteristics. An all-fiber Brillouin laser with a maximum unsaturated power of 54.6 mW at 1550 nm and a slope efficiency of 38.2% are achieved from a 200 m tellurite fiber by employing a ring cavity. In addition, a tunable Brillouin comb tellurite fiber laser is demonstrated.     

Preparation of 3-(4-chlorophenyl)-2-(2-aminothiazol-4-yl)-5-methoxybenzo[b]furan derivatives and their leukotriene B(4) inhibitory activity

A series of 3-(4-chlorophenyl)-2-(2-aminothiazol-4-yl)benzo[b]furan derivatives 6-10 were prepared and their leukotriene B(4) inhibitory activity was evaluated. We found that several compounds showed strong inhibition of calcium mobilization in CHO cells overexpressing human BLT(1) and BLT(2) receptors. Among them, 3-(4-chlorophenyl)-2-[5-formyl-2-[(dimethylamino)methyleneamino]thiazol-4-yl]-5-methoxybenzo[b]furan 9b showed the most potent and selective inhibition for the human BLT(2) receptor, and its IC(50) value was smaller than that of the selected positive control compound, ZK-158252.     

Hadron-quark phase transitions in hyperon stars

The Gibbs and Maxwell constructions for the hadron-quark phase transition in neutron and protoneutron stars, including interacting hyperons in the confined phase, are compared. We find that the hyperon populations are suppressed and that neutrino trapping shifts the onset of the phase transition. The effects on the (proto)neutron star maximum mass are explored.     

Effect of alkoxy terminal chain length on mesomorphism of 1,6-disubstituted pyrene-based hexacatenar liquid crystals: columnar phase control

Synthesis and mesophase-transition behaviors of six 1,6-disubstituted pyrene-based hexacatenar liquid crystals 1_n (n=8–18) are reported here. They were synthesized by the Sonogashira coupling between 1,6-diethynylpyrene and 2-bromothiophene bearing a trialkoxybenzoyl group. The phase-transition behavior was studied by differential scanning calorimetry and polarized optical microscopy; a few mesophase progressions, I–Col/I–X–Col and Col–Sm, were observed, where X was an optically isotropic but unidentified phase. The structures of Col_r, Col_h, and Sm phases were analyzed by the X-ray crystallography, and the effect of the terminal alkoxy chain length on the mesomorphism was evaluated.     

Quantitative Rietveld texture analysis of CaSiO(3) perovskite deformed in a diamond anvil cell

The Rietveld method is used to extract quantitative texture information from a single synchrotron diffraction image of a CaSiO(3) perovskite sample deformed in axial compression in a diamond anvil cell. The image used for analysis was taken in radial geometry at 49?GPa and room temperature. We obtain a preferred orientation of {100} lattice planes oriented perpendicular to the compression direction and this is compatible with [Formula: see text] slip.     

Observations of fission-tracks in zircons by atomic force microscope

The fission-track (FT) method is a dating technique based on the observation of damage (tracks) by spontaneous fission of ²³⁸U left in a mineral. The date is calculated from the track density and the uranium concentration in the mineral. This is possible because the number of tracks is a function of uranium concentration and time since the start of track accumulation. Usually, the number of tracks is counted under an optical microscope after etching (chemical expansion of a track). However, as FT density per unit area rises, it becomes difficult to count the number of tracks. This is due to the fact that FTs overlap one another and are unable to be readily distinguished. This research examines the potential of atomic force microscope (AFM) for FT dating using zircons, which are likely to show higher FT density than other minerals due to their high U concentrations.To obtain an AFM image for a sample prepared for FT dating, removing the static electricity of the sample is essential to avoid an unexpected movement of the cantilever. A grain should be wider than about 30 μm to bring the cantilever on the mineral surface. Polishing with a fine grained compound is very important. There is not much difference in sharpness between images by AC mode (scanning with vibrating cantilever at a constant cycle) and Contact mode (scanning with the cantilever always in close contact with the surface). To confirm how tracks can be identified with the AFM, an AFM image was compared with an image obtained with the optical microscope. When change in the number of tracks and their shapes were observed through stepwise etching, the track expanded as the etching time increased. In addition, the etching rate was slower for large tracks than those for small tracks. This implied that the AFM can be used to observe etching of zircons with different degrees of nuclear fission damage. A track that could not be seen with the optical microscope due to insufficient etching could be observed by AFM methods, indicating the possibility of FT dating with high track densities using AFM after relatively short etching periods.     

Polymer design for thermally stable polyimides with low dielectric constant

We successfully prepared a series of thermally stable polyimides (PIs) with low dielectric constant (k) by introducing bulky diphenyl fluorenylidene moieties in backbone. The lowest k was found to be 2.77 among non-fluorinated PIs and 2.35 among fluorinated ones. In order to prove the lowest limit of k in PIs, we prepared soluble and thermally stable polyarylenes (PArs) without polar imide linkage with the same aromatic moieties by coupling polymerization. The lowest k was 2.7 without fluorine (F) and 2.2 with F atom, which showed also promising for low k materials. From these results, PIs we prepared were estimated to the lowest k values among PIs. On the basis of statistics on these results, we could express contour lines of k as a function of imide concentration and F content with high correlation factor (r= 0.96) in PIs and PArs.