Fabrication of porous SiC ceramics having pores shaped with Si grain templates

SiC porous ceramics were prepared by heating mixtures of Si powder and carbon black at 900 °C for 24 h in Na vapor. The grains of the Si powder were not only the source of Si for SiC but also served as templates for the pores in the SiC porous ceramics. Angular-shaped pores with sizes of 2-10, 10-150 and 50-150 μm were formed by angular Si grains with sizes of ≤10, ≤50 and ≤150 μm, respectively. The porosity of the SiC porous ceramics was around 55-59%. Spherical pores were also formed when spherical Si grains were used. A bending strength of 14 MPa was measured for the SiC porous ceramics prepared with the Si grains (≤50 μm).     

Soft-type polyurethane foams derived from molasses

Molasses (ML)-based soft-type polyurethane (PU) foams were successfully prepared by controlling evolved heat during chemical reaction. Two kinds of isocyanate, poly(phenylene methylene) polyisocyanate (MDI) and tolylene diisocyanate (TDI), and polypropylene glycol with a long molecular chain length were utilized to control the chemical reaction. The hydroxyl group in ML was used as the reaction site and soft-type PU foams were synthesized at isocyanate (NCO)/hydroxyl group (OH) ratios of 1.05. Mechanical properties of the above foams were controlled by changing the mixing ratio of MDI and TDI. Pore size and distribution were measured by scanning electron microscopy. With increasing thickness of cell wall, compression strength and modulus increased. Thermal properties of PU foams were investigated by differential scanning calorimetry, thermogravimetry, and thermal conductivity measurements. Two-step glass transition temperatures were observed at around ca. ?55 and 80 °C, regardless of kind of isocyanate. The low temperature side glass transition is attributed to the molecular motion of long oxyethylene chains and the high temperature side transition is caused by rigid components including saccharide components. Thermal decomposition of PU foams started from ca. 270 °C. Thermal conductivity of soft-type PU was observed in a range from 0.034 to 0.035 J s^?1 m^?1 K^?1.     

Improving the photovoltaic performance of co‐evaporated Cu2ZnSnS4 thin‐film solar cells by incorporation of sodium from NaF layers

We have investigated the influence of sodium (Na) on the properties of co‐evaporated Cu₂ZnSnS₄ (CZTS) layer microstructures and solar cells. The photovoltaic performance and diode properties were improved by incorporating Na from NaF layers into the CZTS layers, while Na had a negligible effect on the microstructural properties of the layer. The best cell fabricated by using an optimal CZTS layer (Cu/(Zn + Sn) = 0.70, Zn/Sn = 1.8) yielded an active area efficiency of 5.23%. The analysis of device properties suggests that charge‐carrier recombination at CZTS/CdS interface is suppressed by intentional Na incorporation from NaF layers. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis of zirconia sphere particles based on gelation of sodium alginate

Zirconia sphere particles were synthesized through the gelation process of Na-alginate, and cermet (ZrO₂-Mo) pellets were fabricated under several conditions. In this process, a zirconia slurry was prepared by mixing oxide powders (ZrO₂, Y₂O₃, Er₂O₃, CeO₂), distilled water and Na-alginate, and subsequently dropped into CaCl₂ solution. As a result, zirconia sphere particles coated with a gelled film were synthesized. The slurry density (zirconia content in slurry) of 30-64 wt.% and Na-alginate concentration of a few% were good for gelation for up to 10 wt.% CaCl₂ solution. Sphere particles with smaller diameter were obtained by dropping slurry with a mechanical vibration. The prolongation of the ball milling time for mixture of oxide powders was effective to increase the sintered density of zirconia sphere particles, especially for higher CeO₂ concentration. The dense cermet pellets were fabricated for max. 50% volume ratio of zirconia phase for Mo matrix using zirconia particles covered with Mo powder by a rotating granulation method.     

Anhydrous proton conductor consisting of pectin–inorganic composite material

An organic–inorganic proton conductive composite material consisting of a biopolymer was prepared by mixing the pectin, tetraethyl titanate, and imidazole. Although the pectin material without the composite dissolved in water, the pectin–inorganic composite material did not show water solubility. In addition, in the composite material, the pectin and imidazole formed an acid–base structure by an electrostatic interaction, and as a result, these composite materials showed a thermal stability at intermediate temperatures (100–200°C). Furthermore, these composite materials indicated the proton conductivity of 5.6 × 10^?4 S cm^?1 at 180°C under anhydrous conditions. The activation energy of the proton conduction under anhydrous conditions was 0.32–0.22 eV and these values were one order of magnitude higher than that of the typical humidified perfluorinated membrane, such as Nafion^®. The organic–inorganic composite material consisting of a biocomponent may have the potential to be utilized as a novel proton conductor under anhydrous conditions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42433.     

Liposome‐Based in Vitro Evolution of Aminoacyl‐tRNA Synthetase for Enhanced Pyrrolysine Derivative Incorporation

Methanosarcina species pyrrolysyl‐tRNA synthetase (PylRS) attaches Pyl to its cognate amber suppressor tRNA. The introduction of two mutations (Y384F and Y306A) into PylRS was previously shown to generate a mutant, designated LysZ‐RS, that was able to attach N‐benzyloxycarbonyl‐L ‐lysine (LysZ) to its cognate tRNA. Despite the potential of LysZ derivatives, further LysZ‐RS engineering has not been performed; consequently, we aimed to generate LysZ‐RS mutants with improved LysZ incorporation activity through in vitro directed evolution. Using a liposome‐based in vitro compartmentalization (IVC) approach, we screened a randomly mutagenized gene library of LysZ‐RS and obtained a mutant that showed increased LysZ incorporation activity both in vitro and in vivo. The ease and high flexibility of liposome‐based IVC should enable the evolution of not only LysZ‐RS that can attach various LysZ derivatives but also of other enzymes involved in protein translation.     

A geometric method of sector decomposition

We propose a new geometric method of IR factorization in sector decomposition. The problem is converted into a set of problems in convex geometry. The latter problems are solved using algorithms in combinatorial geometry. This method provides a deterministic algorithm and never falls into an infinite loop. The number of resulting sectors depends on the algorithm of triangulation. Our test implementation shows smaller number of sectors comparing with other existing methods with iterations.     

Lateral Inhomogeneity in the Electronic Structure of a Conjugated Poly(3‐hexylthiophene) Thin Film

How annealing influences the morphology of a highly regioregular poly(3‐hexylthiophene) (RR‐P3HT) film at the substrate interface as well as the lateral inhomogeneity in the electronic structure of the film are elucidated. Whereas previous studies have reported that high‐molecular‐weight (MW) RR‐P3HT films tend to show low crystallinity even after annealing, it is found that high‐MW RR‐P3HT does show high crystallinity after annealing at high temperature for a long time. Photoemission electron microscopy (PEEM), X‐ray photoemission spectroscopy, and ultraviolet photoemission spectroscopy results clearly resolve a considerable lateral inhomogeneity in the morphology of RR‐P3HT film, which results in a variation of the electronic structure depending on the local crystallinity. The PEEM results show how annealing facilitates crystal growth in a high‐MW RR‐P3HT film.