Solid lubrication by multiwalled carbon nanotubes in air and in vacuum

Aligned and dispersed multiwalled carbon nanotubes (MWNTs) were evaluated for solid lubrication applications. Results obtained from unidirectional sliding friction experiments indicate that MWNTs have superior friction properties and sustainability in air and vacuum. Based on analyses of wear surfaces, transfer films, wear debris, and microstructures, the lubrication mechanism of the MWNTs is discussed.†NASA Resident Research Associate at Glenn Research Center     

Hyper expression of kojibiose phosphorylase gene and trehalose phosphorylase gene from Thermoanaerobacter brockii ATCC35047 in Bacillus subtilis and selaginose synthesis utilizing two phosphorylases

The kojibiose phosphorylase (KP) gene and trehalose phosphorylase (TP) gene from Thermoanaerobacter brockii ATCC35047 were intracellularly hyper-expressed under the control of the Bacillus amyloliquefaciens alpha-amylase promoter in Bacillus subtilis. The production yields were estimated to be 2.1 g of KP and 4.9 g of TP per liter of medium. Selaginose, non-reducing trisaccharide, was synthesized from trehalose utilizing the recombinant KP and TP from B. subtilis. Selaginose was not hydrolyzed by salivary amylase, artificial gastric juice, pancreatic amylase, or small intestinal enzymes.     

Small-angle X-ray scattering study on the structure and crystallization of amorphous Fe-P-C alloy

The change in structure of an amorphous Fe-P-C alloy during ageing was examined using small-angle X-ray scattering (SAXS) measurement and transmission electron microscopy. The SAXS intensity was related to two different types of scattering regions depending on ageing time and temperature. The major scattering was from the crystalline particles, which had two-phase lamella structures. The average thickness of the lamellae remained constant at about 5 nm during ageing. The interlamella distance was three to five times the lamellar thickness in the regular packing region. Another minor scattering was interpreted as being caused by the local ordering of atomic configuration in the amorphous state. The average size of the scattering region was 1.8 to 2.4 nm and quite similar to the critical range proposed by Giessen and Wagner, beyond which the shortrange order disappears.     

Production of arachidonic acid by filamentous fungus, Mortierella alliacea strain YN-15

A filamentous fungus producing significant levels of arachidonic acid (AA, C20∶4n−6) was isolated from a freshwater pond sample and assigned to the species Mortierella alliacea. This strain, YN-15, accumulated AA mainly in the form of triglyceride in its mycelia. An optimized culture in 25 L of medium containing 12% glucose and 3% yeast extract yielded 46.1 g/L dry cell weight, 19.5 g/L total fatty acid, and 7.1 g/L AA by 7-d cultivation in a 50-L jar fermenter. Assimilation of soluble starch by YN-15 was notably enhanced by the addition of oleic acid, soybean oil, ammonium sulfate, or potassium phosphate to a starch-based medium. Using starch as a main carbon source in the pre-pilot scale cultivation improved the production of AA by up to 5.0 g/L. Mortierella alliacea strain YN-15 is therefore a promising fungal isolate for industrial production of AA and other polyunsaturated fatty acids.     

Design of transmission line filters and matching circuits using genetic algorithms

A method for designing microwave filters and impedance matching circuits using transmission lines is presented. Transmission line filters with shunt‐connected open circuit stubs and continuously varying transmission line matching circuits are described in detail. The proposed method is based on genetic algorithms and can effectively be applied to various filter and matching circuit design problems without increasing theoretical and computational complexity. Design examples are provided, and the proposed method is demonstrated to be effective in designing transmission line filters and matching circuits. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Tailor‐Made Designer Helical Peptides that Induce Mitochondrion‐Mediated Cell Death without Necrosis

Managing protein–protein interactions is essential for resolving unknown biological events at the molecular level and developing drugs. We have designed and synthesized a side‐chain‐crosslinked helical peptides based on the binding domain of a pro‐apoptotic protein (Bad) that induces programed cell death. The peptide showed high helical content and bound to its target, Bcl‐X_L, more strongly than its non‐crosslinked counterparts. When HeLa cells were incubated with the crosslinked peptide, the peptide entered the cytosol across the plasma membrane. The peptide formed a stable complex with Bcl‐X_L localized at the outer mitochondrial membrane, and this binding event caused the release of cytochrome c from the intermembrane space of mitochondria into the cytosol. This activated the caspase cascade: 70 % of HeLa cells died by the apoptosis pathway (without evidence of necrosis).     

Carbon nanotube sheets used in field-emission lamps with vacuum-sealed diode structures

We applied carbon nanotube (CNT) sheets, which are high-purity and suitable for mass production, to field-emission lamps (FELs) with vacuum-sealed diode structures. Three such FELs were designed and fabricated to correspond to the field-emission characteristics of individual CNT sheets. We suppressed the variation in the anode–cathode voltage to within the range of 5.4–6.0 kV, which contributes to the light output of the FELs. The stabilities of the FELs ranged from ?0.65% to 0.26% in the short term; therefore, we confirmed that the high-purity CNT sheets were stable during operation. All FELs could be operated for 500 h without significant degradation, even when the FEL was operated in a passive vacuum instead of a dynamic vacuum.     

Production of olefins from ethanol by Fe and/or P‐modified H‐ZSM‐5 zeolite catalysts

BACKGROUND: Much attention has been paid to the catalytic conversion of ethanol to olefins, since biomass resources such as ethanol are carbon‐neutral and renewable, and olefins are useful as both fuels and chemicals. It has been reported that zeolite H‐ZSM‐5 is effective for converting ethanol to hydrocarbons, with the chief products being aromatic compounds. RESULTS: Successive addition of Fe and P to the H‐ZSM‐5 improved the initial selectivity for propylene, while the sole addition of Fe or P and co‐addition of Fe and P showed medium initial selectivity. In general, catalysts showing higher initial selectivity for propylene exhibited a steeper decrease in propylene selectivity with time on‐stream. The cause of the change in product selectivity may be carbon deposition during reaction. Addition of Fe and P can improve catalytic stability when processing both neat and aqueous ethanol. The catalytic performance was regenerated by calcination in flowing air. CONCLUSION: Fe‐ and/or P‐modified H‐ZSM‐5 zeolite catalysts efficiently produced olefins (especially propylene) from ethanol. Effective catalyst regeneration was achieved by calcination in flowing air. Copyright © 2010 Society of Chemical Industry