Yoshitaka Sato

A novel function of tissue-type transglutaminase: protein disulphide isomerase.

We have found that tissue-type transglutaminase (tTG), also called TGc, TGase2 and Galpha(h), has the activity of protein disulphide isomerase (PDI). We have shown that tTG converts completely reduced/denatured inactive RNase A molecule to the native active enzyme. The PDI activity of tTG was strongly inhibited by bacitracin, which is a frequently used inhibitor of conventional PDI activity. It was substantially inhibited by the simultaneous presence of other potential substrate proteins such as completely reduced BSA, but not by native BSA. This activity was especially high in the presence of GSSG, but not GSH. The addition of GSH to the reaction mixture in the presence of GSSG at a fixed concentration up to at least 200-fold excess did not very substantially inhibit the PDI activity. It is possible that tTG can exert PDI activity in a fairly reducing environment like cytosol, where most of tTG is found. It is quite obvious from the following observations that PDI activity of tTG is catalysed by a domain different from that used for the transglutaminase reaction. Although the alkylation of Cys residues in tTG completely abolished the transglutaminase activity, as was expected, it did not affect the PDI activity at all. This PDI activity did not require the presence of Ca(2+). It was not inhibited by nucleotides including GTP at all, unlike the other activity of tTG.

High-efficiency and economical solar-energy-pumped laser with Fresnel lens and chromium codoped laser medium

The authors achieved 11%–14% slope efficiency of solar-pumped laser by Cr-codoped Nd:yttrium aluminum garnet ceramic and Fresnel lens focusing from natural sunlight. The laser output of 24.4W was achieved with 1.3m2 Fresnel lens. The maximum output for unit area of sunlight was 18.7W∕m2, which is 2.8 times larger than previous results with mirror collector. The utilization of Cr3+ ion enabled efficient absorption and energy transfer to Nd3+ ion of solar spectrum. The fluorescence yield at 1064nm for various pumping wavelengths was measured both for Crcodoped and nondoped laser media, and 1.8 times enhancement of laser output from sunlight is predicted.

Noncatalytic dissociation of MgO by laser pulses towards sustainable energy cycle

We succeeded in dissociating MgO using laser pulses without a reducing agent. The energy efficiency from laser to magnesium reaction energy exceeded 42.5%. Although 1kW CO2 cw laser and Nd-YAG pulse laser are used in this experiment, the laser can be pumped by natural resources such as solar light or wind power. Thus natural resources are stored in the form of magnesium, which can be used through the reaction with water whenever we need the energy, and thus a renewable energy system will be established. This paper reports the preliminary experiments of MgO reduction toward a sustainable energy cycle.

Laser-induced magnesium production from magnesium oxide using reducing agents

Experiments for laser induced production of magnesium (Mg) from magnesium oxide (MgO) using reducing agents (R) were conducted. In these experiments, continuous wave CO2 focused laser is focused on a mixture of magnesium oxide and reducing agent. High power density of focused laser leads to high temperature and the reduction reaction resulting in Mg production. The resultant vapor is collected on a copper plate and analyzed in terms of magnesium deposition efficiency. Deposition efficiencies with various reducing agents such as Zr, C, and Si have been measured to be 60, 9.2, and 12.1 mg/kJ respectively. An excess addition of reducing agent over their corresponding reaction stoichiometric amounts is found to be optimum condition for the most of performed laser induced reactions. In addition, utilizing solar-pumped laser in Mg production with reducing agent will reduce CO2 emission and produce magnesium with high-energy efficiency and large throughput.

Synthesis of optically active furfuryl alcohols and butenolides from trans-1-trimethylsilyl-3-alken-1-ynes via successive asymmetric dihydroxylation and hydromagnesiation reactions

Abstract Optically active furfuryl alcohols and hydroxy butenolides are prepared from trans-1-trimethylsilyl-3-alken-1-ynes by the successive asymmetric dihydroxylation and hydromagnesiation reactions.

Experimental Study of Magnesium Production with Laser for Clean Energy Cycle

A new scheme of generating power called magnesium injection cycle [MAGIC] engine was developed. Magnesium [Mg] and water are put into the chamber and ignited at 500 degree Celsius. Mg reaction with water produces hydrogen [H2] gas. The hydrogen blows out and reacts with oxygen [O2] gas to generate H2O and energy at the exit nozzle. These reactions occur simultaneously and generate thrust. In order to reproduce Mg, the residual MgO is irradiated by focused cw CO2 laser (1000 W) at 20 Pa. Then, high temperature (over 4000 degree Celsius) is exerted in tiny spot thus MgO reduction in equilibrium is achievable. Spectroscopic analysis was conducted on the Mg/MgO vapor under atmospheric condition. The Mg line at 518 nm, MgO line at 500 nm and O+ line were confirmed. This proves that the MgO is dissociated by laser irradiation These experiments confirm that the scheme can be used for magnesium energy cycle system with practical efficiency and large throughput.

Time-resolved measurement of photon emission during fast crack propagation in three-point bending fracture of silica glass and soda lime glass

Simultaneous time-resolved measurements of photon emission (PE) and fast crack propagation upon bending fracture were conducted in silica glass and soda lime glass. Observation of fracture surfaces revealed that macroscopic crack propagation behavior was similar between the silica glass and soda lime glass when fracture loads for these specimens were comparable and cracks propagated without branching. However, a large difference in the PE characteristics was found between the two glasses. In silica glass, PE (645–655 nm) was observed during the entire crack propagation process, whereas intense PE (430–490 nm and 500–600 nm) was observed during the initial stages of propagation. In contrast, only weak PE was detected in soda lime glass. These results show that there is a large difference in the atomic processes involved in fast crack propagation between these glasses, and that PE can be used to study brittle fracture on the atomic scale.

An efficient approach to optically active benzoprostacyclins by a two-component coupling process

A highly efficient and practical synthesis of enantiomerically pure benzoprostacyclins, chemically stable and therapeutically useful prostaglandin I2 analogues, is developed which includes an efficient preparation of 2-[3-bromo-2-(allyloxy)phenyl]-4-siloxycyclopent-2-en-1-one 3 in optically active form and the conjugate addition of ω side-chains onto 3 followed by cyclization to the key intermediate (1R, 2R, 3′S)-2-endo-siloxy-1-exo-(3′-siloxyalk-1-enyl)-3a,8b-cis-2,3,3a,8b-tetrahydro-1H-5-bromocyclopenta[b]benzofuran 4.