Hemicellulose Composition in Different Cell Wall Fractions Obtained using a DMSO/LiCl Wood Solvent System and Enzyme Hydrolysis

In our previous studies on the relationships between lignin structure and hemicellulose composition in a wide range of hardwood species, we showed that the higher the syringyl ratio, the higher the xylan/mannan ratio. In this study, the relationship of the syringyl ratio and xylan/mannan ratio was further studied using fractions obtained by stepwise extraction of finely milled beech wood by use of aqueous dioxane and subsequent dimethyl sulfoxide (DMSO)/LiCl solvents with increasing LiCl concentration. Each soluble fraction obtained with a different LiCl concentration was compared with the corresponding insoluble residue, and it was shown that both the syringyl ratio and xylan/mannan ratio were always higher in the insoluble fraction. To analyze polysaccharides closely located with lignin, milled wood lignin (MWL), and cellulolytic enzyme lignin (CEL) obtained by enzyme treatment after DMSO/LiCl swelling were investigated. Although the xylan/mannan ratio of MWL was higher, that of CEL with more than 80% lignin yield was lower.     

Fabrication of Functionally Graded SiO2‐Mo Material by Centrifugation and Floc‐Casting of Highly Concentrated Slurry

To fabricate functionally graded materials, a highly concentrated slurry of SiO₂‐Mo system was prepared and centrifugal force was applied in an attempt to achieve a graded composition. Subsequently, we formed a homogeneous green body with compositional gradation by floc‐casting at 80°C, which was then fired at 1750°C for 10 min in Ar. The sintered body had compositional ratios of SiO₂ and Mo as well as electrical conductivities that changed gradually along the direction of centrifugal force. The results demonstrate that centrifugation and control of slurry characteristics such as flocculation are effective in fabricating functionally graded SiO₂‐Mo materials.     

Corrosion characteristics of reduced activation ferritic steel, JLF-1 (8.92Cr–2W) in molten salts Flibe and Flinak

Static corrosion tests were performed in molten salts, LiF–BeF₂ (Flibe) and LiF–NaF–KF (Flinak), at 500 °C and 600 °C for 1000 h. The purpose is to investigate the corrosion characteristics of reduced activation ferritic steels, JLF-1 (8.92Cr–2W) in the fluids. The concentration of hydrogen fluoride (HF) in the fluids was measured by slurry pH titration method before and after the exposure. The HF concentration determined the fluoridation potential. The corrosion was mainly caused by dissolution of Fe and Cr into the fluids due to fluoridation and/or electrochemical corrosion. Carbon on the surface might be dissolved into the fluids due to the corrosion, and this resulted to the decrease of carbide on the surface. The corrosion depth of the JLF-1 specimen, which was obtained from the weight losses, was 0.637 μm in Flibe at 600 °C and 6.73 μm in Flinak at 600 °C.     

Experimental and numerical study on hydrodynamics of riparian vegetation

Recently, many channelized rivers tend to be heavily vegetated due to regime shifts in hydrological, fluvial and ecological processes. Dense vegetation in a river frequently obstructs a flood flow and reduces conveyance capacity of channels. On the other hand, river vegetation provides various ecological services such as habitats for various species and life, natural cycle of organic and inorganic substances, etc.. It is of engineering importance to understand vegetation hydrodynamics in order to preserve vegetation nature and keep a certain level of flow conveyance capacity. In view that willows tend to be densely vegetated along the shoreline of floodplains or sandbars, a field measurement, a physical model experiment and a numerical analysis were carried out for investigating hydrodynamics in an open channel with riparian vegetation. Discussion was made focusing on flow and shear layer structures developed around the vegetation canopy.     

In vitro bioactivity evaluation of nano- and micro-crystalline anodic TiO2: HA formation,cellular affinity and organ culture

Anodization is an easily viable technique useful for producing TiO₂ coatings on titanium substrates. Nano-crystalline anodic TiO₂ structure was produced on titanium at 20 V using 1 M Na₂SO₄ and 0.5% NaF and consolidated by a further heat-treatment. Micro-crystalline anodic TiO₂ was produced on titanium by applying a galvanostatic current density of 70 A/m² in water medium. To assess the usefulness of these nano- and micro-oxides for bone implant stability, physical properties and bone in vitro bioactivity including HA formation, cellular affinity and mouse-tissue morphogenesis, were evaluated. Bioactivity of the different anodic surfaces was evaluated by treating them in a simulated body fluid (SBF) to form hydroxyapatite (HA) and the rates of HA formation were compared. Deposits of HA could be seen on the nano-oxide surface within 7 days, whereas HA was detected only after 14 days on the micro-oxide surface. In vitro cell culture tests done using mouse osteoblasts indicated that the nano-oxides showed statistically significant cell activity than the micro-oxides and the machined titanium. Branching morphogenesis test done for 72 h on these surfaces showed more branching on the micro- and nano-oxides as compared with titanium surface.     

Reentrant Spin Glass and Large Coercive Field Observed in a Spin Integer Dimerized Honeycomb Lattice

2D magnetic materials with dimerized honeycomb lattices can be treated as mixed-spin square lattices, in which a quantum phase transition may occur to realize the Bose–Einstein condensation of magnons under reachable experimental conditions. However, this has never been successfully realized with integer spin centers. Herein, a spin integer (S = 2) dimerized honeycomb lattice in an iron(II)-azido compound [Fe(4-etpy)₂(N₃)₂]_n (FEN, 4-etpy = 4-ethylpyridine) is realized. Morphology characterization by transmission electron microscopy, scanning electron microscopy, and atomic force microscopy spectroscopies show that the thinnest place of the sample is ≈13 nm, which is equal to ten layers of the compound. In contrast to the common magnetic properties of long-range magnetic ordering, Mössbauer and polarized neutron scattering studies reveal that FEN exhibits a reentrant spin glass behavior owing to competing ferro- and antiferromagnetic exchange-coupling interactions within the lattice. Two spin glass phases with disparate canting angles are characterized at 39 and 28 K, respectively. By using Curély's model, two exchange-coupling constants (J₁ = +35.8 cm⁻¹ and J₂ = −3.7 cm⁻¹) can be simulated. Moreover, a very large coercive field of ≈1.9 Tesla is observed at 2 K, making FEN a “very hard” van der Waals 2D magnetic material.     

Nanoimprint Lithography Facilitated Plasmonic-Photonic Coupling for Enhanced Photoconductivity and Photocatalysis

Imprint lithography has emerged as a reliable, reproducible, and rapid method for patterning colloidal nanostructures. As a promising alternative to top-down lithographic approaches, the fabrication of nanodevices has thus become effective and straightforward. In this study, a fusion of interference lithography (IL) and nanosphere imprint lithography on various target substrates ranging from carbon film on transmission electron microscope grid to inorganic and dopable polymer semiconductor is reported. 1D plasmonic photonic crystals are printed with 75% yield on the centimeter scale using colloidal ink and an IL-produced polydimethylsiloxane stamp. Atomically smooth facet, single-crystalline, and monodisperse colloidal building blocks of gold (Au) nanoparticles are used to print 1D plasmonic grating on top of a titanium dioxide (TiO₂) slab waveguide, producing waveguide-plasmon polariton modes with superior 10 nm spectral line-width. Plasmon-induced hot electrons are confirmed via two-terminal current measurements with increased photoresponsivity under guiding conditions. The fabricated hybrid structure with Au/TiO₂ heterojunction enhances photocatalytic processes like degradation of methyl orange (MO) dye molecules using the generated hot electrons. This simple colloidal printing technique demonstrated on silicon, glass, Au film, and naphthalenediimide polymer thus marks an important milestone for large-scale implementation in optoelectronic devices.     

Development of a three-dimensional finite element model for a unidirectional carbon fiber reinforced plastic based on X-ray computed tomography images and the numerical simulation on compression

A unidirectional carbon fiber reinforced plastic (CFRP) was scanned by an X-ray computed tomography (CT) system. Based on the X-ray CT images, a three-dimensional model with random fiber waviness was developed. Each fiber location was identified in a sectional CT image. Subsequently, the relative displacement of fibers between adjacent sectional CT images was obtained with a digital image correlation method. This procedure was repeated to obtain fiber waviness along the axial direction. The constructed three-dimensional fiber model showed random waviness of each fiber in the unidirectional CFRP. Finite element analysis was performed using the three-dimensional model. Simulation results showed bending and twisting deformations coupled with axial contractions during axial compression, which developed due to fiber waviness. A reduction of the fiber directional Young’s modulus due to fiber random waviness was quantitatively evaluated.     

An efficient manufacturing method for I-shaped cross-sectional CFRP beam with arbitrary arrangement of carbon fiber using electro-activated resin molding

Abstract

The I-shaped cross-sectional beam of CFRP (CFRP I-beam) is usually manufactured by the continuous protrusion method. Carbon fibers can only be arranged in the longitudinal direction. The CFRP I-beam with arbitrary arrangement of carbon fiber was manufactured with applying the electro-activated deposition molding method. The carbon fiber fabric was immersed in the deposition solution and energized, epoxy resin precipitated around carbon fiber and impregnated. The resin-impregnated fabric was installed to the mold, and the CFRP I-beam was fabricated. The CFRP I-beam was subjected to three-point bending tests, and the relationship between load-deflection was simulated by finite-element analysis.     

Enhanced catalytic activity of nanoshell carbon co-doped with boron and nitrogen in the oxygen reduction reaction

The use of carbon cathode catalysts in polymer electrolyte fuel cells instead of the current platinum catalysts is attracting increasing attention. We claim that two factors are important for enhancing the activity of carbon cathode catalysts in the oxygen reduction reaction (ORR): the formation of a nanoshell structure and co-doping with boron and nitrogen. Herein, we investigate the preparation and characterization of active ORR carbon catalysts that combine the above factors. Boron and nitrogen (BN)-doped nanoshell-containing carbon (BN-NSCC) was prepared by carbonizing a mixture of poly(furfuryl alcohol), cobalt phthalocyanine, melamine, and a trifluoroborane–methanol complex at 1000 °C. Transmission electron microscopy and X-ray photoelectron spectroscopy revealed the formation of nanoshell structures with distorted graphitic layers and the introduction of boron and nitrogen atoms, respectively. The ORR activity was evaluated in oxygen-saturated 0.5 mol dm^?3 H₂SO₄ using Koutecky–Levich analysis. The BN-NSCC showed an eight to ten times higher ORR activity than undoped NSCC, with an increased number of electrons participating in the reaction. Tafel analysis revealed a change in the rate-determining step caused by BN-doping. Thus, the combination of a nanoshell structure and co-doping with boron and nitrogen was found to improve the ORR activity of carbon catalysts.