Development of a recombinant ε-poly-L-lysine synthetase expression system to perform mutational analysis

ε-Poly-L-lysine (ε-PL) synthetase (Pls), which is a membrane protein with adenylation and thiolation domains characteristic of the nonribosomal peptide synthetases, catalyzes polymerization of L-lysine molecules (25-mer to 35-mer). Here, we report on the development of a recombinant Pls expression system that allowed us to perform a site-directed mutational analysis.     

Reconstitution and function of Tetragenococcus halophila chaperonin 60 tetradecamer

Tetragenococcus halophila originally isolated from soy sauce is a halophilic lactic acid bacterium which can grow under 4 M sodium chloride. T. halophila chaperonin composed of a core moiety of chaperonin 60 (cpn60) and a lid moiety of chaperonin 10 (cpn10), is thought to contribute to host halotolerant capability. In this report, we reconstituted and characterized the core complex of T. halophila chaperonin by using a recombinant T. halophila cpn60 (Tcpn60) overexpressed in Escherichia coli. The reconstitution of Tcpn60 was performed in the presence of 10 mM MgCl2, 2 mM ATP and 0.8 M (NH4)2SO4 and the resultant oligomer was purified by gel filtration chromatography. Electron microscopy of the reconstituted Tcpn60 revealed a double toroidal tetradecameric structure that is characteristic of bacterial cpn60. The T. halophila tetradecamer cpn60 exhibited an ATPase activity and a refolding activity of both chemically and thermally denatured enolases under wide range of salt concentrations. Furthermore, we demonstrated that heterologous expression of Tcpn60 allowed the normal growth of host Escherichia coli cells under salt stress conditions and this effect was further enhanced by co-expression with Tcpn10. These results suggested that Tcpn60 contributes to the halotolerance property of T. halophila cell as a tetradecamer complex, probably associated with the Tcpn10 complex.     

Energy system based on hydrodynamic power in Yakushima Island

Yakushima Island was used as a model area where material recycling and indigenous energy systems would be realized based on the zero-emission concept in the near future. We evaluated the renewable energy resources to propose a regional energy system on this island. In this paper, the present energy demand and supply structure was quantitatively specified, and the water potential was evaluated. The energy system in Yakushima is unique, with hydroelectric power supplying about 30% of the total energy consumption mainly by commercial and residential sectors. However, petroleum remains the main source of primary energy for transportation, heating, and cooking. The hydroelectric power yielded on the island is sufficient to cover all the energy demands on the island. We found that fossil fuel energy in Yakushima could be substituted with hydroelectric energy without causing an impact on the environment.     

Electrochemical modification of active carbon fiber electrode and its application to double-layer capacitor

Electrochemical oxidation of an active carbon fiber (ACF) electrode showed an enhancement effect of the electrode capacitance. The modification of ACF, however, increased the electrode inner resistance with an increase in the capacitance. Au deposition, the deaeration and the electrochemical reduction (discharge) after the modification showed a decrease in the inner resistance. Thus, the capacitor using the modified ACF electrodes with deaeration. Au deposition and/or discharge treatment showed an enhancement of capacitance with decreasing inner resistance.     

Study on the Application of Kenaf Core as a Composite Reinforcement: Injection Molding of Kenaf Core/Poly(l-lactide) Compounds

Injection molding was performed using poly(l-lactide) (PLLA) as a matrix and by varying the reinforcements, i.e., dry-distilled kenaf core (D-core) or untreated kenaf bast fibers, and the physical properties for these composites were subsequently compared. The dry-distillation was able to reduce the moisture content of D-core by a maximum of 4.2% as compared with untreated control core. As a result, the hydrophobicity was increased, which contributed to favorable Charpy impact strength and tensile properties of the D-core/PLLA composite relative to the kenaf bast fiber/PLLA composite. Moreover, the puffing phenomenon, which arises when heating with a microwave oven due to the vaporization of water dispersed within the interfacial regions and associated softening of the PLLA matrix by the heated vapor, was completely suppressed for the D-core/PLLA composite, whereas a large puffing ratio was observed for the kenaf bast fiber/PLLA composite. Reducing the moisture content also effectively suppressed the occurrence of transesterification reactions, leading to a decrease in the molecular weight of PLLA. However, the apparent nucleation effect of the D-core remains slightly inferior to that for the hydrophilic bast fibers due to its stronger affinity for PLLA molecules.     

Numerical evaluation of group-pile foundation subjected to cyclic horizontal load

In this paper, three-dimensional (3D) finite element analyses of a real-scale group-pile foundation subjected to horizontal cyclic loading are conducted using a program named DBLEAVES. In the simulations, nonlinear behaviors of ground and piles are described by subloading t_ij model and the axial-force dependent model (AFD model) which considered the axial-force dependency in the nonlinear moment-curvature relations. In order to consider the influence of an effective stress path on the prediction of the group-pile foundation, the analyses are conducted within the framework of the soil-water coupling method with finite-difference and finite-element regime. The material parameters of soils are determined based on conventional triaxial drained compression tests on undisturbed and remolded specimens. The applicability of the proposed numerical method is encouraging, and therefore, it is quite confident to say that the method can be used to predict the mechanical behaviors of group-pile foundation to a satisfactory accuracy, particularly with the effective stress analysis.     

Liquefaction of palm kernel shell in sub- and supercritical water for bio-oil production

The heavy palm oil industry in Malaysia has generated various oil palm biomass residues. These residues can be converted into liquids (bio-oil) for replacing fossil-based fuels and chemicals. Studies on the conversion of these residues to bio-oil via pyrolysis technology are widely available in the literature. However, thermochemical liquefaction of oil palm biomass for bio-oil production is rarely studied and reported. In this study, palm kernel shell (PKS) was hydrothermally liquefied under subcritical and supercritical conditions to produce bio-oil. Effects of reaction temperature, pressure and biomass-to-water ratio on the characteristics of bio-oil were investigated. The bio-oils were analyzed for their chemical compositions (by GC–MS and FT-IR) and higher heating values (HHV). It was found that phenolic compounds were the main constituents of bio-oils derived from PKS for all reaction conditions investigated. Based on the chemical composition of the bio-oil, a general reaction pathway of hydrothermal liquefaction of PKS was postulated. The HHV of the bio-oils ranged from 10.5 to 16.1 MJ/kg, which were comparable to the findings reported in the literature.     

Crystal Growth of Rod-Shaped β-LiA1O2

LiAlO₂crystals are obtained conventionally in the form of powder. In a few publications, crystal growth of rod-shaped LiAlO₂ has been described, but the fiber length was very short, <4 μm. In the present study, rod-shaped β-LiAIO₂ crystals 10 to 15 μm long were grown using LiOH-AI₂O₃NaOH as the raw material.     

A Temperature Programmed Desorption Technique for Investigation of Practical Catalysts

Thermal desorption of gases from solids can be used as a simple technique for probing into the details of bonding between a gas and a solid. The flash filament method, a specific version of thermal desorption, involving use of ultra-high vacuums to follow desorption of an adsorbate from a rapidly heated filament, is a well-established technique that has provided a great deal of very valuable information on adsorption of gases on clean metal surfaces.