Light-Driven Hydrogen Production by Hydrogenases and a Ru-Complex inside a Nanoporous Glass Plate under Aerobic External Conditions.

Hydrogenases are powerful catalysts for light-driven H2 production using a combination of photosensitizers. However, except oxygen-tolerant hydrogenases, they are immediately deactivated under aerobic conditions. We report a light-driven H2 evolution system that works stably even under aerobic conditions. A [NiFe]-hydrogenase from Desulfovibrio vulgaris Miyazaki F was immobilized inside nanoporous glass plates (PGPs) with a pore diameter of 50 nm together with a ruthenium complex and methyl viologen as a photosensitizer and an electron mediator, respectively. After immersion of PGP into the medium containing the catalytic components, an anaerobic environment automatically established inside the nanopores even under aerobic external conditions upon irradiation with solar-simulated light; this system constantly evolved H2 with an efficiency of 3.7 µmol H2 m(-2) s(-1). The PGP system proposed in this work represents a promising first step toward the development of an O2-tolerant solar energy conversion system.

Formation of color centers in a soda-lime silicate glass by excimer laser irradiation.

We have investigated defect generation in soda-lime silicate and iron-doped soda-lime silicate glasses by excimer laser irradiation in order to apply coloration due to radiation-induced defects as a coloring technique for practical glass products. The laser irradiation generated various kinds of defects, i.e., non-bridging oxygen hole centers (NBOHCs), E' centers, and trapped electron centers, as does x-ray and γ-ray irradiation. The amounts of generated NBOHCs, monitored by the absorption intensity, increased at first with the irradiation time for both the ArF and XeF lasers, and eventually became saturated. The saturated values for the ArF laser irradiation were almost the same regardless of the laser intensity, whereas those for the XeF laser irradiation were dependent on the intensity; a higher intensity generated a larger amount of NBOHCs. From the comparison of the energies of the photon and the absorption edge of the soda-lime silicate glasses, the defect generation reactions were expected to be one-photon and two-photon processes for the ArF and XeF lasers, respectively. In order to explain the defect generation behavior, we used a simple kinetic model in which the NBOHCs are reversibly generated and annihilated through the photo-reaction. The model includes a stretched exponential function, which is often observed for reactions occurring in amorphous materials. The dependences of the amounts of the generated NBOHCs on the irradiation time and intensity of the laser pulses derived from the model were consistent with the experimental results.

Extraction of heavy metal ions from waste colored glass through phase separation.

A new method utilizing phase separation phenomena for the extraction of heavy metal ions used as colorants in colored glass is proposed. Colored soda-lime-silica glass containing Co or Cr as a colorant was remelted with B2O3 to yield soda-lime-borosilicate glass. The soda-lime-borosilicate glass thus obtained was leached in 1M nitric acid at 90 degrees C to dissolve the borate phase. All cations (Na, Ca, Cr and Co) concentrated in the borate phase are successfully leached out with the dissolution of the borate phase, when the amount of the B2O3 added to the glass and heat treatment conditions are properly chosen. Porous silicate glass powders with high SiO2 purity are obtained as the result of the leaching. Porous glass can also be formed as bulk material by controlling the composition of additives during the remelting.

Light-controlled gas permeability of mesoporous silica glass bearing photochromic spironaphthoxazine on its surface.

N2 and CO2 gas permeability of mesoporous silica glass bearing photochromic indolinospironaphth[2,1-b][1,4]oxazine through a covalent linkage was controlled by photo-irradiation: the photo-isomerization of the spironaphthoxazine to the photomerocyanine form suppressed the gas permeation of the glass.

Fading behavior of X-ray induced color centers in soda-lime silicate glass.

The X-ray induced color centers in soda-lime silicate glass were unstable at room temperature. There was a rapid fading at short-term stage and a slow fading at long-term stage. In the short-term stage, both first-order and second-order fading kinetics played roles in the fading process, while only the first-order fading controlled the long-term stage fading.

High-selectivity, high-flexibility glass hollow-fiber membrane for gas separation.

A high gas selectivity, high flexibility glass hollow-fiber membrane based on spinodal phase separation has been prepared by direct winding from glass melt, followed by acid leaching processing.

X-ray irradiation on the soda-lime container glass.

X-ray irradiation induced defects in the commercial soda-lime container glass were studied by means of optical spectrophotometer and ESR. The induced color might be applied to producing recyclable glasses. The nonbridging oxygen hole centers (NBOHCs) were mainly responsible for the irradiation induced absorptions at 431 and 627 nm of glass. The absorption at 305 nm was attributed to the trapped electron. The induced deep color can be kept for longer than 7 months, but can be almost bleached at 300 degrees C for 20 min.