Oxidative coupling of methane over some titanates based perovskite oxides

A series of perovskites of the formula Ca_1–xSr_xTi_1–yM_yO_3– (M = Fe or Co,x = 0–1,y = 0–0.6 for Fe,y = 0–0.5 for Co) were prepared and tested as the catalyst for the oxidative coupling of methane. The catalysts were stable under the reaction conditions. The catalysts of high p-type and oxide ionic conductivity afforded the high selectivity. Some catalysts containing Co on B-sites are thermally unstable and decomposed to metal oxide components at high temperature, giving rise to synthesis gas production.     

Selective catalytic reduction of NOx with propylene in the presence of oxygen over Co–Pt promoted H-MFI and HY

Kinetic and in situ spectroscopic studies of Co–Pt/MFI and Co–Pt/HY catalysts for the selective reduction of NO_x with propylene in the presence of oxygen were carried out. The results of catalytic tests of Co–Pt/MFI showed that the addition of Pt to Co based catalyst improved the activity, but a small increase in selectivity to N₂O (15–20%) was observed. In the case of Co–Pt/HY catalyst, the addition of Pt improved the activity more significantly and however, a larger increase in selectivity to N₂O (6–72%) was obtained. It was also found from the results of FT-IR studies of Co–Pt/MFI that the reduction of NO to N₂ was as follows: firstly the oxidation of NO to NO₂ occurred over metallic Pt and NO₂ forms Co–NO₂, Co–ONO, and/or Co–ONO₂; secondly, the partial oxidation of C₃H₆ was happened over Brønsted acid sites and the reaction of NO₂ formed on Co sites with partial oxidized C₃H₆ produced organo-nitro species. These species were dehydrated and isomerized to form isocyanate. Finally, [NCO] type intermediates react with NO from gas phase to selectively yield N₂.     

Polypeptide spheres. VII. Macroreticulation of spherical poly(γ-methyl-L-glutamate) beads

Spherical beads from poly(γ-methyl-L -glutamatate) alone were prepared using various diluents for macroreticulating by the “suspension and evaporation” method. The porosity and the pore size of the beads obtained were remarkably dependent on the chemical structure of a diluent. This is related to the specific miscibility of a diluent with poly(γ-methyl-L -glutamate). For example, decahydronaphthalene made the beads much more macroporous than tetrahydronaphthalene with similar hydrophobisity: the aromaticity of diluent increases the miscibility. However, it was found that long-chain alkyl compounds with a miscible group such as methyl dodecanoate, oleic acid, linoleic acid, and dialkyl-phthalate were not only very effective for macroreticulating, but also induced narrow pore-size distribution. In addition, the diluent influenced physicochemical properties of the beads to cause specific affinity to proteins.     

Anatase Titanium Dioxide Crystallization by a Hydrolysis Reaction of Titanium Alkoxide without Annealing

The crystallization of anatase titanium dioxide (TiO₂) was achieved by a hydrolysis reaction of titanium alkoxide without annealing. The hydrolysis reaction rates of tetraethyl orthotitanate were indicated by a function of the concentration of acetylacetone added. The degree of crystallinity of the product particles was influenced by the amounts of acetylacetone and seed crystals. Anatase TiO₂ was crystallized by restraining the rapid increase in supersaturation of TiO₂ and the consequent nucleation of amorphous TiO₂. The degree of crystallinity of the product particles also changed with the types of seed crystals used, and was strongly influenced by the specific surface areas of the seed crystals.     

Discharge through a Permeable Rubble Mound Weir

The hydrodynamics of a rubble-mound weir are theoretically and experimentally examined. This type of weir is considered to be environmentally friendly, since its permeability allows substances and aquatic life to pass through longitudinally. By performing a one-dimensional analysis on a steady nonuniform flow through the weir, discharge is described as a function of related parameters, such as flow depths on the up- and downstream sides of the weir, porosity, and grain diameter of the rubble mound, weir length, etc. A laboratory experiment is carried out to determine the empirical coefficients included in the analytical model. The theoretical solution of the discharge is compared with the experimental data to verify the analysis. It is confirmed that agreement between theory and experiment is satisfactory for a wide range of flow conditions. The present study makes it possible to apply the rubble mound weir for practical use as a discharge control system.     

Direct Microrolling Processing on a Silicon Wafer

Although, varieties of micro‐ to nanoscale fabrication technologies have been invented and refined for silicon (Si) processing because Si is the basic material of integrated circuits, the layouts are based on layer‐by‐layer approaches, making it difficult to realize three‐dimensional (3D) structures with complicated shapes normal to the planar surface (along the out‐of‐plane direction) of the wafers used. Here, a novel and direct Si‐processing technology that enables to bend thin layers of Si surfaces into various 3D curved structures at the micrometer scale is introduced. This bending is achieved by porosifying a Si wafer surface using anodic oxidation and then performing conventional photolithography patterning and wet etching. The porosity gradient in the depth direction gives rise to a stress‐internalized layer in which self‐rolling action is induced via subsequent patterning and wet etching. A subsequent oxidation process further enhances the curvature deformation, leading to the formation of tubes, for example. The rolling directions can be controlled by 2D patterning of the porous Si layer, which is explained well from a structural dynamics perspective. This technology has a wide range of capabilities for realizing 3D structures on Si substrates, enabling new design possibilities for Si‐based on‐chip devices.     

Reduction of interlayer Co2+ ions in fluorine mica using diethylene glycol

Reduction of interlayer Co²⁺ ions in expandable fluorine mica has been attempted. The polyol process using diethylene glycol as a reducing agent was employed. The co²⁺ -exchanged mica was refluxed at about 225–235 °C in liquid diethylene glycol for 10–120 minutes. Consequently, zero-valence Co metal (Co⁰) intercalated mica having a metallic grey colour was obtained by in situ reduction of interlayer Co²⁺ ions, showing different properties from Co²⁺ -exchanged mica as a precursor. The layer charge of Co-metal-intercalated mica is compensated by protons which are produced through the course of reduction of interlayer Co²⁺ ions. The reduced sample heated at 350 °C, which had no organic molecules, exhibited a basal spacing of 1.28 nm, indicating the presence of 0.34 nm cobalt metal clusters after subtracting the thickness of the host silicate layer. During the process of reduction in diethylene glycol, cobalt metal particles were expelled from the interlayers which grew to about 0.5 m onto the external surfaces of host mica crystals with increasing refluxing time.     

Improvement of adhesion and long‐term adhesive reliability of liquid crystalline polyester film by plasma treatment

Surface modification of thermotropic liquid crystalline aromatic polyester (LCP) films was examined by low‐pressure plasma treatment to improve initial adhesion and long‐term adhesive reliability between the LCP film and an epoxy bonding sheet for printed circuit boards. Plasma irradiation was carried out in various plasma gases with different plasma modes as reactive‐ion‐etching (RIE), direct‐plasma (DP) with pressures ranging from 4.0 to 26.6 Pa. Although the initial adhesion of the DP‐treated film increased, the long‐term adhesive reliability estimated by pressure cooker test (PCT) decreased with decreasing the plasma gas pressure in every gas. The higher concentration of the generated polar groups such as phenolic hydroxyl group and carboxyl group enhanced the initial adhesion by the increase in the chemical interaction; however, it damaged the long‐term adhesive reliability due to the acceleration of the penetration of water molecules into the interface. The large surface roughness was effective to enhance the initial adhesion and the long‐term adhesive reliability. The RIE‐treatment generated the polar groups and the larger surface roughness than the DP‐treatment. The RIE‐treatment in the O₂ atmosphere at the gas pressure of 13.3 Pa was the best plasma condition for both the initial adhesion and the long‐term adhesive reliability. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

An improved thermal response test for U-tube ground heat exchanger based on optical fiber thermometers

As part of a new thermal response test (TRT) and to determine ground thermal conductivities, vertical temperature profiles were obtained using retrievable optical fiber sensors inserted into the U-tubes of two ground heat exchangers (GHEs) installed at Maebaru City (Fukuoka, Kyushu) and Kushiro City (Hokkaido), Japan. Measured profiles and outlet temperatures from TRTs were history-matched with the cylindrical source function. Nonlinear regression was used to estimate the vertical distribution of ground thermal conductivities. The computed distribution is consistent with measured data indicating both the reliability of the optical fiber thermometer and TRT interpretation. It is expected that TRTs and optical fiber thermometers will prove to be increasingly useful for optimizing the depth of the GHEs installed in heterogeneous formations, and consequently will minimize installation costs of geothermal heat pump systems.