Preparation of Co–Mo/B2O3/Al2O3 catalysts for hydrodesulfurization: Effect of citric acid addition

The effect of citric acid (CA) addition was studied on the HDS of thiophene over Co–Mo/(B)/Al₂O₃ catalysts. The catalysts were characterized by means of LRS, Mo K-edge EXAFS, NO adsorption capacity measurements, and UV–vis spectra. The catalysts were subjected to a chemical vapor deposition (CVD) technique using Co(CO)₃NO as a precursor of Co in order to get deeper insights into the effect of citric acid addition. It was shown that the HDS activity was enhanced by the citric acid addition up to the CA/Mo mole ratio of around 1 and leveled off with further addition. The amount of Co anchored by the CVD was increased by the addition of citric acid, suggesting an increase in the dispersion of MoS₂ particles on the catalyst by the simultaneous presence of Co, Mo and citric acid, in conformity with the increase in the NO adsorption capacity. In contrast to Co–Mo catalysts, the edge dispersion of MoS₂ particles in Mo/B/Al₂O₃ was not affected by the addition of citric acid. The LRS, UV–vis spectra and Mo K-edge EXAFS showed that Co–CA and Mo–CA surface complexes are formed by the addition of citric acid. The Co–CA surface complex is more preferentially formed on CoMo/Al than on CoMo/B/Al, in agreement with a greater promoting effect of citric acid at a lower CA/Mo mole ratio for CoMo/Al than for CoMo/B/Al.     

What is the significance of nitrogen-vacancy centers in the doping into diamond?

In order to advance quantum computer after successful synthesis of a qubit (quantum-bit) using a NV (nitrogen-vacancy) center in diamond crystal, the innovation of a NOT processor is strongly demanded. A candidate of it can be one NV center associated with an additional N atom, which is called a NV–N center. Making use of a classical molecular dynamics simulation of N ion implantation into pure diamond with an energy of 200 eV, we have examined the crystallographic structure of “NV–N” centers. However, at low temperature of 30 K, most implanted N atoms became interstitials, thus it was difficult to identify even NV centers.     

Polyacene capacitors

We fabricated two types of polyacene capacitor with extremely stable polyacenic semiconductor (PAS) as the positive and negative electrodes. The first one is a coin-type PAS capacitor (six different sizes), which possesses large capacity with high reliability. Its capacity is much larger than that of the conventional electric double-layer capacitor which uses activated carbon as electrode. PAS capacitor can maintain more than 70% of the initial capacity even after 100 000 cycles. Moreover, this capacitor can be charged and discharged in a few minutes as well as at low rate. The second one is a cylinder-type PAS capacitor (diameter: 18 mm, height: 65 mm) which shows high capacity of 100 F and can discharge at the extremely high rate of 80 C. The coin-type PAS capacitor is currently used for memory back-up of electrical and communication equipment, and the cylinder-type is considered to be useful as power back-up for starting drive parts of electric equipment which needs high power density.     

Processability and mechanical properties for binary blends of PP and LLDPE produced by metallocene catalyst

Processability at extrusion coating and mechanical properties of the films obtained are investigated by means of linear and nonlinear rheological measurements and tensile tests for blends of polypropylene (PP) and linear low‐density polyethylene (LLDPE). Both materials are produced by metallocene catalyst. The processability of PP is found to be improved by the addition of LLDPE; the blend shows low level of motor torque and head pressure in an extruder and small level of neck‐in as compared with pure PP. Further, the anisotropy of ultimate tensile strength, which is prominent for PP, is reduced by blending with LLDPE. As a result, the blend having 20 wt % of LLDPE shows appropriate properties in the molten state for extrusion coating and in the solid state as a film. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Fabrication of 64×64 arrayed-waveguide grating multiplexer onsilicon

A 64 channel arrayed-waveguide multiplexer with 0.4 nm (50 GHz) channel spacing at 1.55 μm has been fabricated using SiO₂-Si waveguides. The authors obtained a crosstalk of less than -27 dB to neighbouring and all other channels. The on-chip insertion loss ranges from 3.1 to 5.7 dB for central and peripheral output ports, respectively     

The effect of chemical reaction on the mixing flow between aqueous solutions of acetic acid and ammonia

The basic characteristics of the reacting mixing flow of two streams were investigated. The reaction between aqueous solutions of ammonia and acetic acid, which produces ammonium acetate, was investigated in terms of the effect on the fluid–fluid interface of the mixing flow relative to fluids that did not react. The reaction between these solutions was negligibly exothermic, and there were minimal differences in density. The velocity field in the reacting mixing flow was quantitatively measured using high-speed time-resolved particle image velocimetry (PIV) and the behavior of the mixing flow was qualitatively investigated using laser-induced fluorescence (LIF). The jet width, the velocity field, the kinetic energy and the turbulent intensities are qualitatively estimated and discussed. It was found that the chemical reaction resulted in the suppression of the mixing flow.     

Effect of Ultrasonication on the Microstructure and Tensile Elongation of Zirconia-Dispersed Alumina Ceramics Prepared by Colloidal Processing

To obtain dense, fine-grained ceramics, fine particles and advanced powder processing, such as colloidal processing, are needed. Al₂O₃ and ZrO₂ particles are dispersed in colloidal suspensions by electrosteric repulsion because of polyelectrolyte absorbed on their surfaces. However, additional redispersion treatment such as ultrasonication is required to obtain dispersed suspensions because fine particles tend to agglomerate. The results demonstrate that ultrasonication is effective in improving particle dispersion in suspensions and producing a homogeneous fine microstructure of sintered materials. Superplastic tensile ductility is improved by ultrasonication in preparing suspensions because of the dense and homogeneous fine microstructure.     

A novel spherical carbon

We developed a novel spherical carbon material. The spherical carbon is composed of a high density of carbon nanotubes or nanofilaments, and includes an oxidized diamond particle as a core. Syntheses of this carbon in high volume with high selectivity may be possible. It is expected that this carbon will be useful as a catalyst material for fuel cells, electric double-layer capacitors, etc.