Poly[(R)-3-hydroxybutyrate] formation in Escherichia coli from glucose through an enoyl-CoA hydratase-mediated pathway

In this study, a new metabolic pathway for the synthesis of poly[(R)-3-hydroxybutyrate] [P(3HB)] was constructed in a recombinant Escherichia coli strain that utilized forward and reverse reactions catalyzed by two substrate-specific enoyl-CoA hydratases, R-hydratase (PhaJ) and S-hydratase (FadB), to epimerize (S)-3HB-CoA to (R)-3HB-CoA via a crotonyl-CoA intermediate. The R-hydratase gene (phaJ(Ac)) from Aeromonas caviae was coexpressed with the PHA synthase gene (phaC(Re)) and 3-ketothiolase gene (phaA(Re)) from Ralstonia eutropha in fadR mutant E. coli strains (CAG18497 and LS5218), which had constitutive levels of the beta-oxidation multienzyme FadB(Ec). When grown on glucose as the sole carbon source, the cells accumulated P(3HB) up to an amount 6.5 wt% of the dry cell weight, whereas the control cells without phaJ(Ac) or fadR mutation accumulated significantly smaller amounts of P(3HB). These results suggest that PhaJ(Ac) and FadB(Ec) played an important role in supplying monomers for P(3HB) synthesis in the pathway. Furthermore, by using this pathway, a P(3HB)-concentration-dependent fluorescent staining screening technique was developed to rapidly identify cells that possess active R-hydratase.     

Structural Distortion and Compositional Gradients Adjacent to Epitaxial LiMn2O4 Thin Film Interfaces

Thin film electrode materials are key components in the development of high rate, high capacity solid‐state Li‐ion batteries. Detailed knowledge of the epitaxial film/substrate(current‐collector) interface structures, which provides insights into epitaxial growth mechanisms and the effects of microstructure on electrochemical properties, is essential for efficient materials and device design. Here we report the epitaxial growth mechanism of a typical cathodic LiMn₂O₄ thin film by exploring the detailed structural and compositional variations in the vicinity of a film/substrate interface using state‐of‐the‐art scanning transmission electron microscopy. Direct observation of atom columns shows the epitaxial film forms an atomically flat and coherent heterointerface with the substrate, but that the crystal lattice is tetragonally distorted with a measurable compositional gradient from the interface to the crystal bulk. The growth mechanism is interpreted in terms of a combination of chemical and physicomechanical effects, namely a complex interplay between the internal Jahn‐Teller distortions induced by oxygen non‐stoichiometry and the lattice misfit strain.     

Epoxy curing reaction studied by using two‐dimensional correlation infrared and near‐infrared spectroscopy

The isothermal curing process of bisphenol A epoxy resin with polyamine reagent (1,6‐diaminohexane) was monitored in situ by using temperature‐controlled Fourier‐transform infrared (FTIR) and Fourier‐transform near infrared (FTNIR) spectroscopy to elucidate the relative changes in functional groups during the curing reaction. It was shown that generalized two‐dimensional correlation spectroscopy can provide new information about the mechanisms and kinetics of the curing process, and the band assignments for complex NIR spectrum associated with this system. The sequential order of relative changes in functional groups during the curing process was examined by generalized 2D correlation spectroscopy and NIR‐IR hetero‐correlation spectroscopy, and the details of the complex epoxy curing reaction involving both primary and secondary amino group were revealed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Trypsins from the pyloric ceca of jacopever (Sebastes schlegelii) and elkhorn sculpin (Alcichthys alcicornis): Isolation and characterization

Trypsins from the pyloric ceca of jacopever (Sebastes schlegelii), TR-J, and elkhorn sculpin (Alcichthys alcicornis), TR-E, were purified by gel filtration on Sephacryl S-200 and Sephadex G-50. The molecular weights of TR-J and TR-E were estimated to be 24,000 Da by sodium dodecyl sulfate–polyacrylamide gel electrophoresis. TR-J and TR-E revealed optimum temperatures of 60 and 50 °C, respectively, and showed the same optimum pH (pH 8.0) for hydrolysis of N-p-tosyl-l-arginine methyl ester. TR-J and TR-E were unstable at above 50 and 40 °C, respectively, and were more stable at alkaline pH than at acidic pH. Thermal stabilities of TR-J and TR-E were highly calcium dependent. These purified trypsin enzymes were inhibited by serine protease inhibitors, such as TLCK and soybean trypsin inhibitor. The N-terminal amino acid sequences of TR-J and TR-E were also investigated. The N-terminal amino acid sequences of TR-J, IVGGYECKPYSQPHQVSLNS, and TR-E, IVGGYECTPHSQAHQVSLNS, were found, and these sequences showed highly homology to other fish trypsins.     

Lightning occurrence data observed with lightning location systems of electric power companies in Japan: 2009–2013

Nine electric power companies in Japan have been collecting lightning data with lightning location systems. Five years of the lightning data (2009–2013) are summarized and analyzed in this paper. The recent annual number of lightning flashes of which the current is more than 10 kA in Japan is around 1 million. The variations of lightning occurrence characteristics by areas, seasons, and so on, are clarified. Meteorological conditions that may affect lightning occurrence are also discussed. Furthermore, we show that there is a clear correlation between the number of lightning strikes and the outage rate of transmission lines. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

High‐frequency equivalent circuit of an induction motor driven by a PWM inverter

This paper deals with the high‐frequency equivalent circuits in an induction motor driven by a PWM inverter. The leakage current flows through stray capacitance among stator windings and iron core (frame) of the induction motor at the switching instants of the inverter transistors. The high‐frequency equivalent circuits are derived based on the frequency characteristics of the high‐frequency zero‐phase impedance and line‐to‐line impedance of the induction motor. The validity of the derived equivalent circuits is confirmed by simulation and experimental results. © 2001 Scripta Technica, Electr Eng Jpn, 135(1): 65–76, 2001     

Polarity Effect and Electromagnetic Radiation of Partial Discharge Accompanying Growth of Electrical Tree

We have investigated the characteristics of radiated electromagnetic (EM) waves from positive and negative partial discharges (PD) in epoxy resin and cross‐linked polyethylene. We found that there is a correlation among the EM level from PD, the positive PD current, and electrical trees. Therefore, the growth of an electrical tree produces a lot of positive PD. We have also investigated the characteristics of the frequency region of EM waves from PD in air, insulating oil, and liquid epoxy in addition to the above insulators. EM waves were detected in the frequency region of 40 MHz to 300 MHz from positive and negative PD in epoxy resin and cross‐linked polyethylene. EM waves were also detected in the frequency region of 40 MHz to 150 MHz from positive and negative PD in air. In the case of insulating oil and liquid epoxy, EM waves were detected in the frequency regions of 40 MHz to 150 MHz from positive PD, and 40 MHz to 250 MHz from negative PD. The frequency region differed depending on the material and the discharge polarity. Our investigation indicates that the cause is differences in electric field strength at the time of PD occurrence.     

Push-Pull Fatigue of Sintered Silicon Nitride Ceramics at Elevated Temperatures

The fatigue tests under push-pull completely reversed loading and pulsating loading were performed for silicon nitride ceramics at elevated temperatures. Then the effects of stress wave form, stress rate, and cyclic understressing on fatigue strength, and cyclic straining behavior, were examined. The cycle-number-based fatigue life is found to be shorter under trapezoidal stress wave loading than under triangular stress wave loading, and to become shorter with increasing hold time under the trapezoidal stress wave loading. Meanwhile, the equivalent time-based life curve, which is estimated from the concept of slow crack growth, almost agrees with the static fatigue life curve in the short and intermediate life regions, showing the small cyclic stress effect and the dominant stress-imposing period effect on cyclic fatigue life. The fatigue strength increased in stepwise stress amplitude increasing test, where stress amplitude is increased stepwise every given number of stress cycles, at 1100° and 1200°C. Occurrence of cyclic strengthening was proved through a gradual decrease in strain amplitude during a pulsating loading test at 1200°C in this material, corresponding to the above cyclic understressing effect on fatigue strength.     

Fracture Resistance Behavior of High‐Thermal‐Conductivity Silicon Nitride Ceramics

Silicon nitride ceramics were prepared from a high‐purity silicon powder doped with 2 mol% Y₂O₃ and 5 mol% MgO as sintering additives via a route of sintering of reaction‐bonded silicon nitride (SRBSN). The materials sintered at 1900°C for 3, 6, 12, and 24 h had thermal conductivities of 109, 125, 146, and 154 W/m/K, and four‐point bending strengths of 786, 676, 608, and 505 MPa, respectively. The fracture toughness values, determined by the single‐edge‐precracked‐beam (SEPB) method, were 8.4, 8.6, 9.7, and 10.7 MPa m^1/2 for the materials sintered for 3, 6, 12, and 24 h, respectively, which were similar to the results measured by the chevron‐notched‐beam (CNB) test method. The materials sintered for longer times (12 and 24 h) showed stronger R‐curve behaviors over longer range of crack extension, in comparison with the materials sintered for shorter times (3 and 6 h).     

Thermal conductivity analysis using three‐dimensional microstructures of gelation freezing derived cellular mullite

The relationship between thermal conductivity and unidirectional cellular mullite microstructures created with the freeze casting route is discussed using actual three‐dimensional (3D) images, in which a homogenization method was conducted with microscopic models created from 3D images, the temperature variation in macroscopic models by the finite element method (FEM), and local heat conduction in microscopic models. The simulation results were consistent with the experimental results. This image‐based modeling technique was thus confirmed to be a strong tool for the prediction of various thermal properties of porous ceramics.