Synthesis and ion transport properties of RE3GaO6 (RE = rare earth) oxide ion conductors

First-principles calculations were conducted, which proposed that members of the RE₃GaO₆ (RE = rare earth) system were oxide ion conductors. This study experimentally verified oxide ion conduction in Dy₃GaO₆, Er₃GaO₆, and Nd₃GaO₆. The sintered bodies were synthesized by a solid-state reaction method, and their properties were characterized. The samples with dopants were observed to be mixed electron and oxide ion conductors. Dy_2.85Ca_0.15GaO_6-δ exhibited oxide ion conductivities of 2.1 × 10^?4 S/cm at 973 K, with an oxide ion transport number of 21 % under O₂ gas flow. Additionally, the Rietveld refinement suggested that oxide ion migration might occur via the oxide ion vacancy between the O2 sites. Overall, the oxide ion conductivities of RE₃GaO₆ increased in the following order: Nd > Dy > Er, which was in good agreement with that predicted by using the first-principles calculations. The discrepancy between the experimentally measured and predicted conductivities was caused by the solid-solution limit at the RE site for the dopants.     

Production of hydrogen-rich gas via reforming of iso-octane over Ni–Mn and Rh–Ce bimetallic catalysts using spray pulsed reactor

The conversion of hydrocarbon fuels such as gasoline and diesel is a potential source for hydrogen production towards various fuel cell systems. A novel spray pulsed mode reactor to create alternate wet and dry conditions on the catalyst surface has been used in this study to enhance the rates of hydrogen production compared with the solid-gas phase reaction due to the improvement of the catalyst reactant contact. The production of hydrogen-rich gas by reforming of iso-octane (2,2,4-trimethylepentane) in the presence of steam and air has been studied at 600 and 700 °C over Ni–Mn and Rh–Ce bimetallic catalysts supported on alumina mesh. The feed rate of iso-octane was varied from 0.553 to 5.53 m mol min^–1 by controlling pulse injection in terms of the width and frequency of injection of iso-octane. Based on the product analysis optimized condition for higher hydrogen production and high H₂/CO ratio has been deduced.     

Functionalized imidazolium ionic liquids as electrolyte components of lithium batteries

Some basic properties and compatibility toward lithium electrode for electrolytes based on substituted imidazolium ionic liquid have been investigated. The ionic liquids having imidazolium cation substituted by methylcarboxyl or cyano group suffers from low conductivity. However, reversible lithium deposition–dissolution process was observed in electrolytes based on these electrolytes. In particular, lithium salt solution in cyanomethyl-substituted imidazolium ionic liquid provided similar cycle efficiency to conventional organic solvent electrolyte at constant-current condition. The mixed ionic liquid electrolyte containing the cyanomethyl-substituted ionic liquid also provided good cycle performance despite of containing large amount of 1-ethyl-3-methyl imidazolium (EMI)-based ionic liquid. Such mixed electrolyte system serves both the stability of lithium electrode process and valid conductivity for practical use.     

Near-IR dye-sensitized solar cells using a new type of ruthenium complexes having 2,6-bis(quinolin-2-yl)pyridine derivatives

New ruthenium(II)-polypyridyl complexes 1a (X=H) and 1b (X=Cl) having 2,6-bis(4-carboxyquinolin-2-yl)pyridine derivatives were synthesized as a sensitizer for dye-sensitized solar cells (DSCs), and their photophysical and photochemical properties were characterized. Both of the complexes showed broad electronic absorption bands in the near-IR region, which were assigned to the metal-to-ligand charge transfer (MLCT) transitions. On the other hand, the photovoltaic performance of the DSCs sensitized with them were different from each other. The DSC sensitized with 1a exhibited higher IPCE value than that of the one sensitized with 1b. The substituent effects on the ligand on photovoltaic performance of the DSCs were examined.     

High-efficiency secretory production of peroxidase C1a using vesicular transport engineering in transgenic tobacco

Horseradish peroxidase isozyme C1a (HRP C1a) is widely used as a reporter enzyme in a variety of detection procedures such as enzyme-linked immunosorbent assay (ELISA) and western blotting. We previously isolated the gene encoding HRP C1a and showed that HRP C1a is at first translated as a preproprotein containing propeptides at its N- and C-termini (N-terminal secretion signal peptide and C-terminal propeptide; CTPP). The signal peptide (sp) is necessary for endoplasmic reticulum (ER) translocation and the CTPP acts as a vacuolar sorting determinant. Furthermore, HRP C1a was secreted into the culture medium from cells expressing the HRP C1a gene without the CTPP region. We optimized the secretory production system of HRP C1a in tobacco plants. To determine a suitable signal peptide for high-efficient secretion of proteins, three types of sp derived from HRP C1a (C1Psp), beta-D-glucan exohydrolase (GEsp) and 38 kDa peroxidase (38Psp) were compared. GE and 38P are secretory proteins highly accumulated in the culture medium of BY2 cells. The secretion efficiency was increased by 34% and 53% when GEsp and 38Psp was used, respectively. Next, we used a translational enhancer, the 5'-untranslated region of Nicotiana tabacum alcohol dehydrogenase gene (NtADH 5'-UTR). The production of HRP C1a was increased by placing NtADH 5'UTR in front of the ORF in BY2 cells. These results indicate that the localization and expression level of recombinant proteins can be controlled by the use of propeptides and 5'UTR, respectively. Finally, high-efficiency secretory production of the HRP C1a was also achieved in transgenic tobacco.