Ring hydrogenation of naphthalene and 1-naphthol over supported metal catalysts in supercritical carbon dioxide solvent

Catalytic ring hydrogenations of naphthalene and 1-naphthol were studied over several supported metal catalysts in supercritical carbon dioxide solvent at low temperature. Higher concentration of hydrogen in supercritical carbon dioxide and lower reaction temperature were responsible for higher catalyst activity and selectivities to the desired partial ring hydrogenated products as compared with those observed in organic solvent for the same catalyst.     

In Situ Observation of Zirconia Particles at 1200°C by High-Resolution Electron Microscopy

Zirconia (ZrO₂) particles (average diameter, 30 nm) were observed in an in situ heating experiment up to 1200°C using a 400-kV high-resolution electron microscope. Thermal vibration of atoms on a (001) surface plane was observed at 1100°C. At 1200°C, grain growth and sintering phenomena were recorded on a videotape, showing (100) lattice planes migrating on a surface of a particle. Direct observation of the sintering process on a lattice level was accomplished for the first time.     

The effect of sputter etching on the surface characteristics of dyed aramid fabrics

Three kinds of aramid fabrics, Technora (modified p-aramid), Conex (m-aramid) and Kevlar (p-aramid), were subjected to sputter etching and argon low-temperature plasma treatments after dyeing in black with disperse dyes. The depth of shade increased considerably on Technora and Kevlar with the sputter etching treatment, but not on Conex fabrics. Argon low-temperature plasma treatment had virtually no effect on the depth of shade on the aramid fabrics.     

Graft polymerization of some vinyl monomers onto acrylic rubber. II. Mechanical properties of graft polymers

Some mechanical properties of styrene and acrylonitrile copolymers grafted onto acrylic rubber are investigated. The impact strength of graft polymers depended upon the nature and the concentration of the catalyst, the composition and the intrinsic viscosity of the rubber, and the acrylonitrile content in the rigid matrix. The most desirable result was obtained when benzoyl peroxide as the catalyst, n-butyl acrylate–acrylonitrile copolymer of 7–10% acrylonitrile content, and about 0–5% acrylonitrile in the rigid matrix were used. Dynamic mechanical tests show the increase in efficiency of rubber modification by the grafted chains. The better weathering resistance of these graft polymers, as compared with commercial ABS plastics, was confirmed.     

Quantitative determination of corrosion products and adsorbed water on copper in humid air containing SO2 by IR-RAS measurements

The time dependency of the amounts of corrosion products and co-existing adsorbed water on copper in humid air containing SO₂ was estimated from a series of in situ time-resolved IR-RAS spectra on the basis of the relations between the band intensities and the mass changes of the corrosion products, which were determined by simultaneous measurement of IR-RAS and QCM. The amounts of both corrosion products increased slowly at the initial stage and later increased rapidly. Although the relative humidity was kept constant, the amount of adsorbed water increased nearly the same behavior as that of corrosion products in the stage of relatively small amounts of corrosion products and later increased rapidly when the amounts of corrosion products increased. In humid air without SO₂, sulfite gradually decomposed and some of it changed into sulfate.     

Penetration treatment of plasma-sprayed ZrO2 coating by liquid Mn alloys

The penetration phenomena of liquid manganese (Mn) alloy into porous ZrO₂ (8 vvt % Y₂O₃) coating plasma sprayed on SS400 steel substrate was studied by heating in a vacuum atmosphere. The improvement in mechanical properties of the coating by heat treatment with liquid Mn alloys was examined. Liquid Mn alloys, such as Mn-Cu, Mn-Sn, and Mn-In, rapidly penetrated the coating and formed a chemical bond between the coating and the substrate. The densification of the ZrO₂ coating occurred when ZrO₂ particles were sintered with liquid Mn alloys that penetrated the porous coating. The dense coating was free of porosity, and its hardness increased after heat treatment with Mn alloys, compared with assprayed ZrO₂ coating. Moreover, the fracture toughness of the coating reached the same levels as those of sintered yttria-stabilized PSZ.     

Scattering mechanism and reduction of insertion losses in a laminated polarization splitter

We experimentally found the unexpected phenomena of scattering in laminated polarization splitters (LPS's) composed of a-Si:H-SiO(2) multilayer and studied its mechanism. The scattering phenomena strongly depend on the incident angle and polarization of the incident light. To reduce the scattering loss in LPS's, a multilayer with flat layer boundaries is fabricated with rf bias sputtering. As a result, the insertion loss of the LPS is reduced to ~ 1 × 10(-3) dB/ μm, which is acceptable for practical uses.     

Theoretical analysis of the spatial phase-matching loci for second-harmonic generation and multiwave-mixing interactions

We report a theoretical analysis on spatial noncolinear phase matching of multiwave mixing and its application to a second-harmonic-generation (SHG) experiment. From the numeric calculations, the noncolinear phase-matching properties in general situations were determined. The theory gives the applicability for all noncolinear phase matching. Fine coincidences between theoretical calculations and observed spatial loci on noncollinear phase-matching SHG were confirmed. Relations that allow the calculation of the noncollinear phase-matching angle for any case of SHG are established. As an example, the noncolinear phase-matched SHG pattern on a screen is calculated numerically in the case of SHG of 1064 nm from a Nd:YAG laser under the phase-matched condition for two organic nonlinear crystals: 1-(2-thienyl)-3-(4-methyphenyl) propene-1 (TC-28), which is biaxial, and (2-furyl) methacrylic anhydride (FMA), which is uniaxial. Experimental results compared quite favorably with the theoretical analysis. Noncolinear phase matching may be of great practical interest in optical multiwave-mixing processes, such as optical parametric oscillation and optical parametric amplification. This technique also can be used for the measurement of crystal optical constants.     

Threshold for Millimeter-Wave (60 GHz)-Induced Ocular Injury

Journal of Infrared, Millimeter, and Terahertz Waves - Millimeter waves (MMW) absorbed by skin or cornea may induce damage by heat. We have developed a 60 GHz MMW exposure-induced eye...     

Delignification kinetics of empty fruit bunch (EFB): a sustainable and green pretreatment approach using malic acid-based solvents

Recently, the development of efficient and environmentally benign solvents has received great attention to replace current harsh organic solvents. In this context, low-transition-temperature mixtures (LTTMs) have emerged as favorable green solvents for biomass delignification. Palm oil biomass, empty fruit bunch (EFB) was pretreated with commercial l-malic acid and microwave hydrothermally extracted cactus malic acid-derived LTTMs at 60, 80, and 100 °C. The LTTMs applied in this study were derived from malic acid–choline chloride–water and malic acid–monosodium glutamate–water with a molar ratio of 2:4:2 and 3:1:5, respectively. Three first-order reactions were used to express the delignification kinetic model of EFB. The first term was based on the initial stage and assigned as infinite due to the fast rate of delignification which could not be detected. The second and third terms were proportional to bulk and residual delignification stages. A good agreement was obtained between the kinetic model and the experimental data obtained in this study with R²?≥?0.91. The activation energies for the delignification reactions using l-malic acid and cactus malic acid-based LTTMs in the bulk and residual stages were approximated as 36–56 and 19–26 kJ/mol and 34–90 and 47–87 kJ/mol, respectively.