Solid-phase combinatorial synthesis of aeruginosin derivatives and their biological evaluation

A 24-member combinatorial library based on the structure of aeruginosin 298-A (1a) was synthesized utilizing solid-phase, and their inhibitory activity against trypsin was evaluated. Among the library, we found that D-Hpla-D-Leu-L-Choi-Agma (1h) is 300 times more potent than the parent natural product 1a.     

Adsorption of unsaturated hydrocarbon moieties on H:Si(111) by Grignard reaction

Grafting of unsaturated hydrocarbon moieties (-CH(2)-CH=CH(2), -CH=CH(2), -CH(2)-CH=CH-CH(3), and -CCH) by a C-Si covalent bond was attempted by the Grignard reaction on hydrogen-terminated Si(111) in tetrahydrofuran solutions. The product adsorbates were monitored by vibrational methods of high-resolution electron energy loss spectroscopy and multiple internal infrared reflection absorption spectroscopy, as well as Auger electron spectroscopy. The temperature and the period of reaction were adjusted so as to preserve the unsaturated carbon-carbon bonds. The -CH(2)-CH=CH(2) group was introduced by a mild reaction condition, with the reservation of the C=C double bond confirmed. The unsaturated bonds in -CH(2)-CH=CH-CH(3) and -CCH were also reserved. Only in the case of -CH=CH(2) was the reservation of the C=C double bond not realized. Unsaturated hydrocarbon moieties are applicable for further organic modification to introduce functional groups, and are prospective materials in nanofabrication and biological application on silicon wafer surfaces.     

Comparative photophysical properties of free-base, bis-Zn(II), bis-Cu(II), and bis-Co(II) doubly N-confused hexaphyrins(1.1.1.1.1.1)

We have comparatively investigated the photophysics of a series of bis-metal doubly N-confused hexaphyrins(1.1.1.1.1.1) using time-resolved fluorescence, femtosecond transient absorption, two-photon absorption measurements, and geometry-optimized ab initio calculations. Bis-Zn(II) and free-base doubly N-confused hexaphyrins exhibit well-resolved and red-shifted B- and Q-like absorption bands compared with porphyrins. Their allowed transitions are (pi,pi) transitions of the hexaphyrin ring, as confirmed by the HOMO and LUMO frontier orbitals based on ab initio calculations at the B3LYP/6-31G level. On the other hand, the absorption spectra of bis-Cu(II) and bis-Co(II) doubly N-confused hexaphyrins are relatively broad, presumably due to large couplings between the metal d-orbitals and pi-electrons of the hexaphyrin ring. Owing to these couplings, bis-Cu(II) and bis-Co(II) doubly N-confused hexaphyrins have much shorter excited-state lifetimes of 9.4 +/- 0.3 ps and 670 fs, respectively, than those (267 +/- 16 and 62.4 +/- 1.2 ps, respectively) of bis-Zn(II) and free-base doubly N-confused hexaphyrins. The two-photon absorption cross section (sigma(2)) values, which are believed to depend strongly on the ring planarity (pi-conjugation), are in line with the excited-state lifetime trends.     

A structural development of an organogel explored by synchrotron time-resolved small-angle X-ray scattering

We investigated the gelation process of 12-hydroxystearic acid (12-HSA)/dodecane gel (turbid gel), 12-HSA/xylene and 12-HSA/toluene gels (transparent gels) by using time-resolved synchrotron small-angle X-ray scattering technique. The fibers were developed via nucleation and growth mechanism, and the induction period was longer at higher temperatures. After the induction period, the fiber growth can be divided into two regimes. In the first stage, the scattering intensity increased with time without appearance of any crystalline peak, and in the second stage (001) peak appeared due to crystalline nucleation. In the former regime, the fibers grew with increasing the cross-sectional size, while in the latter regime, they grew with keeping it almost constant, i.e., with keeping the fiber thickness constant. The fiber thickness for the turbid gel (radius of the gyration R _c of ～100 Å) was thicker than that for the transparent gel (R _c of ～82 Å). The fractal dimensions of the fibrillar aggregates for the turbid gels (2.0–2.3) at various temperatures were larger than those for the transparent gels (1.4–1.6), suggesting that the structure of the former gels is more branching or more compact in comparison with the latter.     

Video-Assisted Rigid Endoscopic Laryngosurgery: Application to Cases with Difficult Laryngeal Exposure

In some cases of microlaryngosurgery, laryngeal exposure with a direct laryngoscope is difficult because of a variety of reasons. In such cases, we now use a long rigid endoscope inserted into the side tube of the direct laryngoscope together with a video system. The lesion can be removed while the phonosurgeon observes the magnified images of the larynx on the video monitor. We describe the surgical procedure together with the preoperative and postoperative evaluation of vocal function in 13 patients with benign laryngeal lesions. A good surgical and vocal outcome was achieved in all cases. The method appeared to be useful for treating dysphonia in patients in whom it was difficult to expose the larynx with a direct laryngoscope.     

Ablation process of silica glass induced by laser plasma soft X-ray irradiation

Silica glass can be machined by irradiation with laser plasma soft X-rays on nano- and micrometer scale. We have investigated the ablation process of silica glass induced by laser plasma soft X-ray irradiation. We observed ionic and neutral species emitted from silica surfaces after irradiation. Dominant ions and neutrals are O⁺ and Si⁺ ions and Si, O, SiO and Si₂ neutrals, respectively. The ions have kinetic energies of 13 and 25 eV, which are much higher than those of particles emitted by evaporation. The energy of laser plasma soft X-rays absorbed to silica glass at a fluence of 1.4 J/cm² is estimated to be 380 kJ/cm³, which is higher than the binding energy of SiO₂ of 76 kJ/cm³. These results suggest that the most of the bonds in silica glass are broken by absorption of laser plasma soft X-rays, that several percent of the atoms are ionized, and that neutral atoms are emitted together with repulsive ions. The process possibly enables us to fabricate nano structures.