Proposal for new catalytic roles for two invariant residues in Escherichia coli ribonuclease HI

Three mutants of Escherichia coli ribonuclease HI, in whichan invariant acidic residue Asp134 was replaced, were crystallized,and their three-dimensional structures were determined by X-raycrystallography. The D134A mutant is completely inactive, whereasthe other two mutants, D134H and D134N, retain 59 and 90% activitiesrelative to the wild-type, respectively. The overall structuresof these three mutant proteins are identical with that of thewild-type enzyme, except for local conformational changes ofthe flexible loops. The ribonuclease H family has a common activesite, which is composed of four invariant acidic residues (Asp10,G1u48, Asp70 and Asp134 in E.coli ribonuclease HI), and theirrelative positions in the mutants, even including the side-chainatoms, are almost the same as those in the wild-type. The positionsof the -polar atoms at residue 134 in the wild-type, as wellas D134H and D134N, coincide well with each other. They arelocated near the imidazole side chain of His124, which is assumedto participate in the catalytic reaction, in addition to thefour invariant acidic residues. Combined with the pH profilesof the enzymatic activities of the two other mutants, H124Aand H124A/D134N, the crystallographic results allow us to proposea new catalytic mechanism of ribonuclease H, which includesthe roles for Asp134 and His124.     

Truly wearable display comprised of a flexible battery,flexible display panel,and flexible printed circuit

In an effort to create a truly flexible and wearable display having a flexible battery as well as a flexible organic light‐emitting diode panel and a flexible printed circuit, a flexible lithium‐ion battery has been developed, and a prototype wrist‐wearable or arm‐wearable display has been fabricated. Owing to improvements in the internal structure and exterior of the lithium‐ion battery, no remarkable changes in charge and discharge curves and the internal state of the electrodes were observed even after conducting a 10,000‐cycle bending test. Therefore, this flexible lithium‐ion battery prototype demonstrated remarkable bending resistance. Thus, we succeeded in fabricating a truly flexible and wearable display comprised of a flexible organic light‐emitting diode panel, a flexible printed circuit, and a flexible battery.     

Fatigue behavior and relation between fatigue resistance and tensile properties of poly(para-phenylene-co-3,4'-oxydiphenylene terephthalamide) fiber

The poly(para-phenylene-co-3,4′-oxydiphenylene terephthalamide) (PPODTA) fiber is one of the high strength organic fibers, and it has been reported that the PPODTA fiber has superior fatigue resistance. The high strength fibers are used in the applications to utilize their high mechanical properties in general. Therefore, the long-term durability of these fibers is also required. In this study, the fatigue tests were conducted for the PPODTA fibers. As a result, it was found that the PPODTA fibers were able to be fractured by the cyclic tensile stress, and the fatigue behavior was influenced by the stress conditions. In addition, the single fiber tensile tests were also conducted for the PPODTA fibers, and the relation between the tensile properties and the fatigue resistance of the PPODTA fiber was investigated. The fatigue resistance of the PPODTA fiber was increased with the decrease of the fiber diameter and the increase of the tensile modulus.     

Dispersion polymerization of methyl methacrylate with three types of comblike fluorinated stabilizers in supercritical carbon dioxide

Dispersion polymerizations of methyl methacrylate in supercritical carbon dioxide were conducted with three types of comblike fluorinate polymer stabilizers: poly(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10‐heptadecafluorodecyl methacrylate) (PHDFDMA), poly(3,3,4,4,5,5,6,6,7,7,8,8,8‐tridecafluorooctyl methacrylate) (PTDFOMA), and poly(2,2,3,3,3‐pentafluoropropyl methacrylate) (PPFPMA). The effect of the polymerization pressure was not significant on the mean diameters of the poly(methyl methacrylate) (PMMA) particles from 20 to 40 MPa. However, the coefficients of variation of the particle diameters produced at 20 MPa ( , where is the number‐basis mean particle diameter), where the heterogeneous phase was found before polymerization, were larger than those produced at 30 and 40 MPa, where the homogeneous phase was found. The mean size of the PMMA obtained with PTDFOMA and PPFPMA strongly depended on the stabilizer concentration compared with that obtained with PHDFDMA. Moreover, the mean size decreased as the carbon dioxide‐philic side chain length increased. As shown by the results of this study, the best stabilizer among the three types of stabilizers for producing PMMA particles was PHDFDMA. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43813.     

Negative effect of divalent metal cations on production of gassericin T, a bacteriocin produced by Lactobacillus gasseri, in milk-based media

A broad-spectrum bacteriocin named gassericin T is produced by Lactobacillus gasseri LA158 in MRS broth, but is minimally produced in milk-based media. Gassericin T production in MRS broth was specifically inhibited by adding divalent metal cations. Such inhibition of gassericin T production depended on the concentration of divalent cations. The addition of trisodium citrate dihydrate (TSC), which is a food-grade chelator of divalent cations, restored gassericin T production both in modified MRS broth containing divalent cations and in milk-based medium. In modified MRS broth, 50 mmol L⁻¹ TSC promoted an over-production of gassericin T. Furthermore, it was confirmed that TSC had a synergistic antibacterial effect with gassericin T. In this study, a cheese-whey-based medium, supplemented with proteose peptone, TSC, and Tween 80, was developed for gassericin T production. These results may contribute to the effective use of bacteriocins for food preservation.     

Isolation and characterization of long-chain-alkane degrading Bacillus thermoleovorans from deep subterranean petroleum reservoirs

Two extremely thermophilic alkane-degrading bacterial strains, B23 and H41, were respectively isolated from deep subterranean petroleum reservoirs in the Minami-aga (Niigata) and Yabase (Akita) oil fields. Both strains were able to grow at temperatures ranging from 50 to 80 degrees C, with optimal growth at 70 degrees C for B23 and 65 degrees C for H41. From 16S rRNA gene sequence analysis and physiological characterization, both strains were identified as Bacillus thermoleovorans (identities of 99.5% and 99.6% to strain DSM 5366, and 98.3% and 98.7% to the type strain LEH-1(TS), respectively). Strains B23 and H41 effectively (60%) degraded n-alkanes longer than C12 and C15, respectively, at 70 degrees C, while strain LEH-1(TS) degraded undecane (C11) most effectively. When B23 and H41 were cultivated in the presence of heptadecane, heptadecanoate and pentadecanoate were specifically accumulated in the cells. These results strongly suggest that the two strains degraded n-alkanes by a terminal oxidation pathway, followed by a beta-oxidation pathway.     

Study of cycle output improvement by work-fluid including phase change material

This paper deals with the output improvement of heating and cooling cycle by using the work-fluid including phase change material.The experimental study is carried out by heat exchange between work-fluid and heat transfer surface.The work-fluid is flown to a high temperature or a low temperature heat transfer surface from the narrow path.In order to increase the amount of the heat transmission,a trace of Diethylether(boiling point 34.8 ℃),as a phase change material(PCM),is added to the work-fluid.The parameters of the experiment are additive amount of PCM,the rotational speed of the displacer piston and the temperature of heat transfer surface.It is clarified that the increasing of engine cycle output is brought by the PCM addition.The effect of PCM addition is evaluated by output ratio which is defined from the experimental cycle output data.The requirements for acquiring the increasing effect of output by adding PCM are clarified.     

Scale-up methodology for tumbling ball mill based on impact energy of grinding balls using discrete element analysis

This paper provides a method to scale-up horizontal tumbling ball mills, i.e. to determine the dimensions of the rotating drum and the drum rotational speed. In order to develop the scale-up methodology, the motion of grinding balls in tumbling ball mills with different drum diameters was calculated using the discrete element method (DEM). The impact energy of grinding balls was numerically analyzed, and the influence of drum dimensions and drum rotational speed on the impact energy was investigated. It was found that scale-up of the rotating drum should be carried out based on the mechanical energy instantaneously applied to the powder and its cumulative amount. The former was evaluated in terms of the frequency distribution of the impact energy and the latter its cumulative amount over the elapsed milling time, which could be controlled by the drum rotational speed and the milling time, respectively. Validity of the proposed scale-up methodology was evaluated through dry grinding experiments of aluminum hydroxide powder, and the experimental results supported its usefulness in practical applications.     

Anisotropic Effective Thermal Conductivity Measurement of Various Kinds of Metal Fiber Materials

Recently, metal fiber materials were made by laminating metal fibers with a diameter of about 30 μm to 300 μm. Since the almost metal fibers were oriented in the horizontal direction (the major axis of the fiber), these metal fiber materials are estimated to be anisotropic with an effective thermal conductivity. However, there is little quantitative data on the anisotropic effective thermal conductivity of the various kinds of metal fiber materials. The purpose of this study is to investigate the anisotropic effective thermal conductivity of various metal fiber materials experimentally and theoretically. In order to measure the horizontal and vertical effective thermal conductivities of these metal fiber materials, new measurement devices were developed. As a result, it is found that the anisotropic effective thermal conductivity of the various metal fiber materials was confirmed, and the horizontal and vertical effective thermal conductivities of these metal fiber materials depend on the bulk density or porosity, Young’s modulus, the fiber length, and fiber diameter. And a dimensionless correlation equation for predicting the vertical and horizontal effective thermal conductivities of the various kinds of metal fiber materials was derived in terms of various dimensionless parameters.