Fabrication of Fine AlN Particles by Pulverizing with Very Small ZrO2 Beads

Nano-sized aluminum nitride (AlN) powders can enhance the sinterability of AlN ceramics. The present work examined the pulverization and dispersion of AlN powder using ZrO₂ beads of 0.1 mm in diameter as grinding medium in order to obtain nano-sized powder for low-temperature sintering. An attracting feature of the bead grinding is that the rotor creates centrifugal and shearing forces, which lead to efficient pulverization that exceeds the conventional grinding limit. The AlN powder with agglomerates and average particle size of 0.38 μm was broken up into more homogeneous particles with a narrow particle size distribution after 90 min of grinding. Qualitative examinations of the powder by transmission electron microscopy and BET indicated that the particle size was 50–100 nm and specific surface area was 70 m²/g.     

Application of transmission electron microscopes to nanometre-sized fabrication by means of electron beam-induced deposition

Electron beam‐induced deposition was carried out using a scanning transmission electron microscope with a field emission gun to fabricate nanometre‐sized structures. A small amount of a metal–organic gas was introduced near the substrate in the microscope chamber, and focused electron beams were irradiated. Two‐ and three‐dimensional structures were fabricated by scanning the beam position. The minimum line width of the freestanding structures was 8 nm at a constant gas flux used. This line width of 8 nm is considered to be achieved by employing a high accelerating voltage, which leads to a small probe size, and the optimum scanning speed.     

Presence of lactoferrin in a bovine skim milk fraction with acid phosphatase activity

The aim of this study was to determine the principal active molecules in the acid phosphatase (AcP) fraction of skim milk origin using immunostaining and AcP staining. The AcP fraction was separated from skim milk at 0.38 m NaCl using carboxymethyl cellulose chromatography at pH 5.2. The molecular mass of the active molecule in AcP fraction was estimated to be 80 kDa by immunostaining and AcP staining. The 80 kDa protein was analyzed by a protein sequencer, using the automated Edman degradation method; the first thirteen N-terminal amino acid sequence obtained were shown to be APRKNVRWXTIXQ. For that amino acid sequence, there was 84% (11/13 residues) homology with the amino acid sequence of bovine lactoferrin (LF). The AcP fraction and commercial LF showed a similar AcP activity profile, having an optimum pH of 4.5 and temperature of 60 °C. Thus, the AcP fraction from bovine skim milk was isolated and the principal active molecule present was tentatively identified as LF.     

Fluid flow and heat transfer of natural convection around array of vertical heated plates

Natural convective flows around an array of vertical heated plates were investigated experimentally. Main concerns were directed to the influences of plate numbers on the heat transfer characteristics of the plates. Both surfaces of the test plates were heated with constant and equal heat fluxes and their local heat transfer coefficients were measured. The results showed that the coefficients of the surfaces of the array facing outward became higher than those facing inward. The flow fields around the bottom of the plate array were visualized with smoke. The result showed that the ambient flow is directed from the sides to the center of the array and enters the parallel channel obliquely. These flows cause the above difference in the coefficients. While the difference gradually diminished in between the plates placed in the central section of the array, their coefficients asymptotically approach those of the analytical correlation that assumed a uniform velocity at the channel inlet. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20232     

Fluid flow and heat transfer of mixed convection adjacent to vertical heated plates placed in uniform horizontal flow of air

Experiments have been carried out for mixed convective flows of air adjacent to the vertical heated plates in uniform horizontal forced flows to investigate relationships between the flow and the heat transfer. The experiments cover the ranges of the Reynolds and modified Rayleigh numbers: Re_L = 160 to 2300 and Ra_L^* = 4.3 × 10⁵ to 2.0 × 10⁸. The flow fields over the plates are visualized with particles and smoke. The results show that a stagnation point moves downward away from the center of the plate when the surface heat flux is beyond a critical value. The condition where the stagnation point begins to move is expressed with non‐dimensional parameters as: Gr_L^*/Re_L^2.5 = 0.15. Profiles of measured local heat transfer coefficients are smooth even at the stagnation points in all the cases examined. When buoyancy effect is sufficiently weak, the coefficients agree well with those of the wedge flow. With increasing the surface heat flux, the coefficients are augmented to approach asymptotically the boundary layer solution of natural convection along a vertical heated plate. Finally, forced, mixed, and natural convection regimes are classified by the non‐dimensional parameter (Gr_L^*/Re_L^2.5). © 2009 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20256     

Enhanced effects of nonisotopic hafnium chloride in methanol as a substitute for uranyl acetate in TEM contrast of ultrastructure of fungal and plant cells

This ultrastructural study showed that nonisotopic methanolic hafnium chloride and aqueous lead solution was an excellent new electron stain for enhancing TEM contrasts of fungal and plant cell structures. The ultrastructural definition provided by the new stain was often superior to that provided by conventional staining with uranyl acetate and lead. Definition of fine ultrastructure was also supported by quantitative data on TEM contrast ratios of organelles and components in fungal and plant cells. In particular, polysaccharides, which were localized in cell walls, glycogen particles, starch grains, and plant Golgi vesicle components, were much more reactive to the new stain than to the conventional one. The new nonisotopic stain is useful for enhancing the contrast of ultrastructure in biological tissues and is a safer alternative to uranyl acetate. Microsc. Res. Tech., 2011. © 2010 Wiley‐Liss, Inc.     

Regulation of Photochemical Energy Transfer Accompanied by Structural Changes in Thylakoid Membranes of Heat-Stressed Wheat

Photosystems of higher plants alleviate heat-induced damage in the presence of light under moderate stressed conditions; however, in the absence of light (i.e., in the dark), the same plants are damaged more easily. (Yamauchi and Kimura, 2011) We demonstrate that regulating photochemical energy transfer in heat-treated wheat at 40 °C with light contributed to heat tolerance of the photosystem. Chlorophyll fluorescence analysis using heat-stressed wheat seedlings in light showed increased non-photochemical quenching (NPQ) of chlorophyll fluorescence, which was due to thermal dissipation that was increased by state 1 to state 2 transition. Transmission electron microscopy revealed structural changes in thylakoid membranes, including unstacking of grana regions under heat stress in light. It was accompanied by the phosphorylation of thylakoid proteins such as D1 and D2 proteins and the light harvesting complex II proteins Lhcb1 and Lhcb2. These results suggest that heat stress at 40 °C in light induces state 1 to state 2 transition for the preferential excitation of photosystem I (PSI) by phosphorylating thylakoid proteins more strongly. Structural changes of thylakoid membrane also assist the remodeling of photosystems and regulation of energy distribution by transition toward state 2 probably contributes to plastoquione oxidation; thus, light-driven electrons flowing through PSI play a protective role against PSII damage under heat stress.     

Fabrication of fluorinated polymer nanosheets using the Langmuir–Blodgett technique: characterization of their surface properties and applications

This review describes the bottom‐up design of ultra‐thin fluorinated polymer films. Fluorinated polymer assemblies offer unique and application‐oriented properties strongly correlated with surface chemistry. We focus on our recent topic of research, fluorinated polymer nanosheets, which are ultra‐thin polymer films fabricated from amphiphilic fluorinated polyalkylacrylamides using the elegant Langmuir–Blodgett technique. These fluorinated polymer nanosheets have excellent hydrophobicity, extremely low surface energy and a low friction coefficient. Therefore, fluorinated polymer nanosheets are attractive nanomaterials for surface modification in terms of tailoring of wettability, frictional properties, adhesion and surface chemistry. The nanocoating technique using reactive fluorinated polymer nanosheets and surface modification of hard disks and microchannels are also reviewed. Copyright © 2010 Society of Chemical Industry     

An approach for protein to be completely reversible to thermal denaturation even at autoclave temperatures

Reversibility of protein denaturation is a prerequisite forall applications that depend on reliable enzyme catalysis, particularly,for using steam to sterilize enzyme reactors or enzyme sensortips, and for developing protein-based devices that performon–off switching of the protein function such as enzymaticactivity, ligand binding and so on. In this study, we have successfullyconstructed an immobilized protein that retains full enzymaticactivity even after thermal treatments as high as 120°C.The key for the complete reversibility was the development ofa new reaction that allowed a protein to be covalently attachedto a surface through its C-terminus and the protein engineeringapproach that was used to make the protein compatible with thenew attachment chemistry.     

Optical and electrochemical properties of oligo(1,5‐dialkoxynaphthalene‐2,6‐diyl)s with self‐assembled ordered structures in solid state

Oligo(1,5‐dialkoxynaphthalene‐2,6‐diyl)s were synthesized by Ni(cod)₂ (cod = 1,5‐cyclooctadiene)‐promoted condensation reactions of 1,5‐dialkoxy‐2,6‐dibromonaphthalenes. The UV–Vis, photoluminescence (PL), and powder X‐ray diffraction (XRD) measurements suggested that the oligomers have a self‐assembling ordered structure in the solid state. The oligomers underwent electrochemical oxidation (p‐doping), which occurred at lower potentials for films than for acetonitrile solutions containing [Et₄N]BF₄. This effect is caused by the longer π‐conjugation lengths of the oligomers in films, which was attributed to molecular self‐assembly leading to ordered structures in the solid state. The electrochemical reaction of the oligomers was accompanied by electrochromism. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41840.