Synthesis of 3D pore mesostructured silica films by vapor infiltration of tetraethoxysilane

Nonionic alkyl poly(oxyethylene) surfactants (Brij 56) films on a silicon substrate were treated with a tetraethoxysilane (TEOS) vapor. Mesostructured silica films were formed through a nano-phase transition under the infiltration of TEOS into the surfactant films. It was found that the calcined film had a 3D pore structure from the field emission scanning electron microscope (FE-SEM) observations in a different orientation. Grazing angle of incidence small angle X-ray scattering (GISAXS) measurement results showed that the symmetry of the film was an Fmmm space group oriented with the (010) plane parallel to the surface. The ordered structure of the films showed higher thermal stability than the films prepared by a conventional solvent-evaporation method.     

Zinc-catalyzed cycloisomerizations. Synthesis of substituted furans and furopyrimidine nucleosides

5-Endo-dig cycloisomerization of 1,4- and 1,2,4- mostly aryl-substituted but-3-yn-1-ones in the presence of a catalytic amount of zinc chloride etherate (10 mol %) in dichloromethane at room temperature gave 2,5-di- and 2,3,5-trisubstituted furans in high yields (85-97%). DSC studies confirmed that a solely thermal process does not take place. A relevant catalytic process, employing mu-oxo-tetranuclear zinc cluster Zn4(OCOCF3)6O, yielded bicyclic furopyrimidine nucleosides, when starting from acetyl-protected 5-alkynyl-2'-deoxyuridines (85-86%). Furopyrimidine was deprotected or simultaneously converted into pyrrolopyrimidine nucleoside. The time/concentration dependence for the reaction of 1-phenyl-4-(4-methylphenyl)butynone to 2-(4-methylphenyl)-5-phenylfuran displayed first-order kinetics with the rate dependent on catalyst concentration. The plot of ln k(obs) versus ln[ZnCl2] indicated first-order cycloisomerization, as referred to ZnCl2 concentration, using both NMR and UV-vis reaction monitoring. The crystal structure of propyl furopyrimidine nucleoside (orthorhombic, P2(1)2(1)2(1), a/b/c = 5.684(2)/6.682(2)/36.02(2) A, Z = 4) shows C2'- endo deoxyribose puckering, and the base is found in the anti position in crystalline form.     

Distinct responses of chloroplasts to blue and green laser microbeam irradiations in the centric diatom Pleurosira laevis

The centric diatom Pleurosira laevis is a large unicellular alga, in which ca 200 chloroplasts migrate toward the nuclear cytoplasm through the transvacuolar cytoplasmic strands in response to blue-light irradiation and, on the contrary, toward the cortical cytoplasm in response to green-light irradiation. We analyzed these light-induced chloroplast migrations using a scanning laser microbeam provided by a confocal microscope for intracellular irradiation. Spot irradiation of a blue laser microbeam induced rapid assemblage of chroloplasts into the nuclear cytoplasm regardless of the spot position and spot number. On the other hand, one or two spots of green laser microbeam induced chloroplast accumulation at the spots, although increasing spot numbers suppressed chloroplast accumulation at each spot. In our experimental condition, ca 1 min of blue-light irradiation was sufficient to stimulate movement, whereas green-light irradiation required uninterrupted and longer irradiation time (ca 15 min). Chloroplast assemblage induced by blue-light required extracellular Ca2+, and was inhibited by Ca2+ channel antagonists. Furthermore, higher efficiencies of chloroplast migration were obtained when a single beam spot was fragmented and scattered over wider area of plasma membrane. These observations suggested that blue-light induced a response at the plasma membrane, which subsequently activated Ca2+ permeable channels. This sequence of physiological events is identical to what was previously observed with chloroplast movement in response to mechanical stimulation. Furthermore, experiments with the cytoskeleton-disrupting agents, colchicine and cytochalasin D, indicated that blue-light-induced chloroplast movement required microtubules whereas the green-light-induced response to beam spot required actin filaments.     

Increased levels of 8-hydroxy-2'-deoxyguanosine in Drosophila larval DNA after irradiation with 364-nm laser light but not with X-rays

Exposure to UVA light causes damage to cellular components such as DNA and membrane lipids. We showed previously that UVA irradiation can induce mutations in Drosophila larvae and that the major lesions responsible for mutations were not thymidine dimers when wavelengths tested became longer. The use of a longer wavelength with UVA laser apparatus (364 nm) has made it possible to test the effects of this powerful light in biological organisms. In the present study, we irradiated third instar larvae of the urate-null Drosophila mutant strain y v ma-l, which is sensitive to oxidative stress, and compared the effects of 364 nm light irradiation with the effects of X-rays. To assay viability, some of the larvae were kept at 25 degrees C until they eclosed in order to obtain a measure of viability. The remaining larvae were used to measure the amount of 8-hydroxydeoxyguanosine (8-OHdG), an indicator of oxidative DNA damage. The amount of 8-OHdG increased and viability decreased in response to increased UV dose in both the y v ma-l and wild-type strains. With irradiation of 600 kJ m(-2), 8-OHdG/10(6)dG was 7.2 +/- 3.2 and 6.2 +/- 2.0 in y v ma-l and wild-type strains, respectively, whereas the respective levels were 2.2 +/- 0.6 and 2.3 +/- 0.8 without irradiation. Our results indicated that irradiation with a 364-nm laser light caused significant oxidative damage in Drosophila larval DNA; however, induction of the damage was not prohibited by urate. To the best of our knowledge, this is the first report of a study in whole animals that shows increased levels of 8-OHdG in response to 364-nm UVA. X-ray ionizing radiation is also thought to generate reactive oxygen species in irradiated cells. We found that the amount of 8-OHdG in DNA following X-ray radiation remained unchanged in both strains, though survival rates were affected. X-ray-generated oxidative damage in Drosophila cells was followed by cell death but not DNA base oxidation, and the damage was suppressed by urate. The overall results suggest significant differences in the major in vivo oxidative damage caused by 364-nm light and X-rays.     

Heterogeneous Pd/C-catalyzed ligand-free, room-temperature Suzuki-Miyaura coupling reactions in aqueous media

A mild and efficient ligand-free Suzuki-Miyaura coupling reaction catalyzed by heterogeneous Pd/C was developed. Aryl bromides and triflates undergo the cross-coupling with aryl boronic acids in excellent yields without the presence of any additives in aqueous media at room temperature. Aryl vinyl boronic acids are also applicable to this coupling reaction and provide the trans-stilbene derivatives in high yields. The application of wet-type Pd/C to the coupling reaction was achieved without any loss of activity under aerobic conditions, and the reuse of Pd/C is feasible for a fifth run without significant loss of activity. Inductively coupled plasma (ICP) mass-spectrometric analysis of the filtrate from the reaction mixture of 4-bromonitrobenzene with phenylboronic acid demonstrated that the palladium metal hardly leached into the solution within the limits of the detector (<1 ppm), thus suggesting that the present Suzuki-Miyaura reaction proceeded by heterogeneous catalysis.     

Hydrolyzed metabolites of thalidomide: synthesis and TNF-alpha production-inhibitory activity

Putative hydrolyzed metabolites of thalidomide were prepared and characterized, and their inhibitory activity on tumor necrosis factor (TNF)-alpha production in the human monocytic leukemia cell line THP-1 was evaluated. Alpha-(2-Carboxybenzamido)glutarimide was a more potent TNF-alpha production inhibitor than thalidomide.     

Tubular Membrane-Like Catalysts for the Oxidative Decomposition of Low-Concentrated Toluene in Air by Periodic Short-Term Plasma Discharge

Plasma Chemistry and Plasma Processing - A porous membrane-like alumina (MA) tube was employed as a catalyst to improve the energy efficiency of the oxidative decomposition of low-concentrated...     

Synthesis and Chiroptical Properties of Quinoxaline-Fused Polyaza[5]–[7]helicenes with Orange-Color CPL Emissions

We achieved a two-type synthesis of quinoxaline-fused polyaza[5]- and [7]helicenes through consecutive N−H/C−H coupling with a hypervalent iodine reagent as a key reaction. By fusing electron-deficient quinoxaline, these polyazahelicenes constitute an efficient donor-acceptor type of molecule with absorption edges that reach up to approximately 650 nm. Evaluating the chiroptical properties reveals that the polyazahelicene exhibits a rare orange circularly polarized glow with a luminescence dissymmetry factor (g_lum value) of 0.003.     

Synthesis of silafluorenes by iridium-catalyzed [2 + 2 + 2] cycloaddition of silicon-bridged diynes with alkynes

[reaction: see text] Silicon-bridged 1,6-diynes underwent [2 + 2 + 2] cycloaddition with alkynes in the presence of an iridium(I)-phosphine catalyst to afford densely substituted silafluorene derivatives. Extended silafluorene skeletons were constructed by the [2 + 2 + 2] cycloaddition of tetraynes.     

Rh-catalyzed cyclization of diynes and enynes initiated by carbonyl-directed activation of aromatic and vinylic C-H bonds

The Rh-catalyzed hydroarylative and hydrovinylative cyclization of diynes with aryl ketones or enones gave monocyclic 1,3-dienes. Enynes also underwent the same reaction and chiral products were obtained with high ee using a chiral Rh catalyst. Carbonyl-directed activation of aromatic and vinylic C-H bonds is likely the initial step in the present transformation.