Temperature programmed oxidation of Cu/ZnO catalysts with N2O: an attempt for characterization of copper catalysts

For characterization of the surface structure of metallic copper formed on the support, temperature programmed oxidation (TPO) with N₂O was carried out over various Cu/ZnO catalysts. Four peaks of the N₂ formation (, , and ) were observed at 223, 400, 545 and 600 K in the TPO runs. The average copper crystallite size estimated from the sum of the amount of - and -peaks agreed fairly with those determined by X-ray diffraction and transmission electron microscopy. It was concluded that - and -peaks resulted from the oxidation of metallic copper atoms on the steps, corners and/ or defect sites, and on the flat sites of the surface of copper crystallites, respectively, while - and -peaks resulted from the bulk oxidation of copper.     

Formation of Liquid Crystalline Order and Its Effect on Thermal Conductivity of AlN/Liquid Crystalline Epoxy Composite

The liquid crystalline (LC) order was introduced on aluminum nitride particles by the surface effect to increase the thermal conductivities of aluminum nitride/LC epoxy composites. X-ray diffraction and grazing incidence small-angle X-ray scattering analyses revealed that the LC epoxy resin cured on the surface of an α-Al₂O₃ substrate formed homeotropically aligned smectic layers to increase the thermal conductivity. Therefore, thermally treated aluminum nitride particles, which formed α-Al₂O₃ layers on their surfaces, were applied to prepare the composites with high thermal conductivity. The thermal conductivities of the resulting composites were 11–36% higher than those with the composites prepared using untreated aluminum nitride particles.     

Multiple degrees-of-freedom arm with passive joints for on-the-machine measurement system by calibrating with geometric solids

To fabricate three-dimensional profiles with high accuracy, on-the-machine measurement is useful. Methods for the on-the-machine measurement by calibration with geometric solids used for references have been developed. In this paper, an arm with passive joints for on-the-machine measurement is proposed. As a prototype, the arm has 4 degrees of freedom (DOF) including two passive joints. The probing system has 7 DOF, including the DOF of the machine tool, in total. Angles of the passive joints are changed by driving the numerically controlled (NC) table and the main spindle of the machine tool, where the arm is mounted. To calculate the optimal posture of the arm for the shape to be measured, a numerical method of the inverse kinematics is also proposed. The arm has enough positioning accuracy to calibrate its posture. Shapes can be automatically measured with the accuracy of micrometer order by the on-the-machine measurement method as well as a commercial three-dimensional (3-D) coordinate measuring machine and a profilometer.     

Fracture Behaviour of Thermoplastic Modified Epoxy Resins

This work has shown that the addition of polyetherimide (PEI) can significantly increase the toughness of highly cross-linked epoxy resins, whilst retaining a high T_g and modulus. These combined properties indicate the potential of PEI modified epoxy resins for use as matrices for advanced composite materials. In terms of G_IC, addition of 20wt% PEI raised the toughness by a factor of eight. Evidence from SEM fracture surfaces suggests that the toughening mechanism operating in bulk PEI modified epoxy resin is ductile drawing of the PEI. Carbon fibre composites based on 30wt% PEI modified epoxy resin matrices show considerable improvement in toughness at low and high strain rates when compared with CFRP possessing unmodified or 20wt% modified PEI content epoxy resins.     

Reduction of lean NOx by ethanol over Ag/Al2O3 catalysts in the presence of H2O and SO2

The reduction of lean NOx using ethanol in simulated diesel engine exhaust was carried out over Ag/Al₂O₃ catalysts in the presence of H₂O and SO₂. The Ag/Al₂O₃ catalysts are highly active for the reduction of lean NOx by ethanol but the reaction is accompanied by side reactions to form CH₃CHO, CO along with small amounts of hydrocarbons (C₃H₆, C₂H₄, C₂H₂ and CH₄) and nitrogen compounds such as NH₃ and N₂O. The presence of H₂O enhances the NOx reduction while SO₂ suppresses the reduction. The presence of SO₂ along with H₂O suppresses the formation of acetaldehyde and NH₃. By infrared spectroscopy, it was revealed that the reactivity of NCO species formed in the course of the reaction was greatly enhanced in the presence of H₂O. The NCO species readily reacts with NO in the presence of O₂ and H₂O at room temperature, being converted to N₂ and CO₂ (CO). Addition of SO₂ suppresses the formation of NCO species and lowers the reactivity of the NCO species. However, the reduction of NOx is still kept at high conversion levels in the presence of H₂O and SO₂ over the present catalysts. About 80% of NOx in the simulated diesel engine exhaust was removed at 743 K. This revised version was published online in July 2006 with corrections to the Cover Date.     

Influence of external magnetic field on permanent magnet by EDM

REMORA aims at offering an agile robotic solution for manufacturing tasks done on very large parts (e.g., very long and slender parts found in aeronautic industries). For such tasks, classical machine tools are designed at several tens of meters. Both their construction and operation require huge infrastructure supports. REMORA is a novel lightweight concept and flexible robotic solution that combines the ability of walking and manufacturing. The robot is a mobile manufacturing system which can effectuate operations with good payload capacity and good precisions for large workspace applications. This new concept combines parallel kinematics to ensure high stiffness but low inertia and mobile robotics to operate in very large workspaces. This results in a machining center of new generation: (1) agile manufacturing system for large workspace applications, (2) heavy load and good precisions, (3) 5-axis machining and 5-axis locomotion/clamping, (4) self-reconfigurable for specific tasks (workspace and force), and (5) flexible and multifunctional.     

Picosecond time-resolved infrared absorption study on photoexcited dynamics of regioregular poly(3-hexylthiophene)

Picosecond time-resolved infrared absorption spectra of the photoexcited states of a spin-coated film of regioregular poly(3-hexylthiophene) (RR-P3HT) have been recorded at 77 K. The time-resolved photoinduced infrared absorptions due to electronic transitions at 2500 cm^?1 and vibrational transitions at 1575 cm^?1 have fast and slow decay components. By comparing the picosecond time-resolved infrared absorption spectrum of long-lived (slow decay component) transient species with the doping-induced infrared difference spectrum of RR-P3HT, the long-lived transient species are assigned to polarons. The short-lived transient species are assigned to singlet excitons and/or polaron pairs.     

Measurement of intrahepatic shunted blood flow by ethanol-1-14C method as compared with D-galactose-1-14C method

The interaction of aflatoxin B1 with a number of biologically important substances has been investigated by spectrophotometric and fluorimetric techniques. The ultra-violet absorption of tryptophan, adenosine, RNA and DNA were altered by the addition of aflatoxin B1. Some amino-acids, purine and pyrimidine derivatives, bovine-serum albumin and DNA quenched the fluorescence of aflatoxin B1. Fluorescence polarization data suggested that the interaction of aflatoxin B1 with bovine-serum albumin was stronger than that with DNA.     

Nucleation and growth of bainite crystals in Cu-Zn-AI alloys

The bainitic transformation in Cu-Zn-Al alloys is known to have both martensitic and diffusion-controlled natures. To study the relation between these two reactions involved in the bainitic transformation, the present authors have performed a series of investigations mainly by optical and electron microscopy. A mechanism whereby directional diffusion of solute atoms stimulates the nucleation and growth of bainite is proposed based upon these investigations. The mechanism is supported by an additional experiment in which a local solute concentration in the matrix crystal is directly measured around the bainite plates using a special analytical electron microscope. This paper is based on a presentation made in the symposium “International Conference on Bainite” presented at the 1988 World Materials Congress in Chicago, IL, on September 26 and 27, 1988, under the auspices of the ASM INTERNATIONAL Phase Transformations Committee and the TMS Ferrous Metallurgy Committee.