Shape-Selective Alkylation of Biphenyl over H-[Al]-SSZ-31 with Propylene

Isopropylation of biphenyl (BP) over [Al]-SSZ-31, a large-pore, one-dimensional zeolite has been studied. Effects of temperature, pressure and SiO₂/Al₂O₃ ratio were examined. SSZ-31 was found to be an active catalyst in the isopropylation of biphenyl with propylene. The selectivity for 4-isopropylbiphenyl (4-IPBP) and 4,4-diisopropylbiphenyl (4,4-DIPB) was high among isopropylbiphenyl (IPBP) and diisopropylbiphenyl (DIPB) isomers, respectively, indicating SSZ-31 shows shape-selective catalysis. The selectivity for 4,4-DIPB decreased with temperature increase; correspondingly the selectivity for thermodynamically more stable isomers (3,3- and 3,4 DIPB) increased with temperature. The yield of IPBP isomers decreased while that of DIPB isomers increased with temperature increase. Pressure showed less effect on conversion; however, increase in pressure suppresses the isomerization of 4,4-DIPB to 3,3- and 3,4-DIPB. Conversion decreased with increase in SiO₂/Al₂O₃ ratio. At low SiO₂/Al₂O₃ ratio of 136, relatively high triisopropylbiphenyl (TriIPB) isomers were formed in bulk products and their amount decreased with increase in SiO₂/Al₂O₃ ratio.     

Effects of modification of highly dispersed cobalt catalysts with alkali cations on the hydrogenation of carbon monoxide

In the hydrogenation of carbon monoxide, alkali cations were found to be effective as modifiers for highly dispersed cobalt catalyst to improve the selectivities of C₂-oxygenated compounds, especially acetic acid and acetaldehyde, and to increase the olefin/paraffin ratio of hydrocarbons. These effects are ascribed to depression of the hydrogenating ability of the catalyst by modification with alkali cations.     

The Hydroamination of methyl acrylates with amines over zeolites

H-form zeolites, H-FAU and H-BEA have been studied as heterogeneous catalysts for the hydroamination. They catalyzed the reaction of methyl acrylate with aniline to give N-[2-(methoxycarbonyl)ethyl]aniline (1) as a main product. H-BEA and H-FAU zeolites efficiently catalyzed the hydroamination to afford anti-Markovnikov adduct as a main product. The conversion of aniline around 55–85% was achieved within 18 h over H-BEA and H-FAU zeolites with SiO₂/Al₂O₃ molar ratio of 25–30; however, the formation of N,N-bis[2-(methoxycarbonyl)ethyl]aniline (2) as a product of double addition of methyl acrylate to aniline has also been observed as a by-product over H-BEA and H-FAU catalysts. The influences of the reaction parameters such as temperature and catalyst amount, and type of α,β-unsaturated esters and amines have been also investigated.     

Mesoporous materials from leached calcium silicates with hollow structure

Mesoporous materials with hollow structures were obtained from leached calcium silicate as silica source. The material with wormhole pores was synthesized using hexadecyltrimethylammonium chloride as a surfactant in basic condition. The material with three-dimensional (3D) cage pores like MCM-48 was obtained using hexadecyltrimethylammonium bromide in basic condition with ethanol as an additive. Both materials have not only regular mesopores but also macropores due to their hollow morphologies. The succession of local dissolution and deposition, with an insoluble part playing as a substrate for precipitation, produced the mesoporous materials which resemble the morphology of the silica source.     

The Di-t-butylation of p-cresol with t-butanol in Supercritical CO2 over Tungstophosphoric Acid Supported on Ordered Mesoporous Silica

Tungstophosphoric acid (HPW) supported on MCM-41 was an excellent catalyst for the t-butylation of p-cresol to 2,6-di-t-butyl-4-methylphenol (2,6-DTBPC) in supercritical CO₂; however, zeolites, H-Y and H-Beta, only gave 2-t-butyl-4-methylphenol (2-TBPC) because of their limitation in pore size. The yield of 2,6-DTBPC was maximized at 110 °C, and further increase in temperature rather decreased the yield. The yield of 2,6-DTBPC was maximized at 10–11 MPa CO₂ pressure, and further increase of the pressure decreased in the conversion of phenol and the yield of 2,4-DTBC. The thermogravimetric analysis of used catalysts showed that the coke-formation was minimized in supercritical CO₂ compared to the other reaction media such as in liquid phase and in N₂ atmosphere.     

Convenient Synthesis of Mesoporous Aluminosilicates by Using Pre-heated Sodium Aluminosilicate Gel

Hydrothermally stable Al-MCM-48 with variety of Si/Al ratios and Al-MCM-41 with tunable pore sizes were successfully obtained from pre-heated aluminosilicate gel precursor. They showed the higher acid strength and hydrothermal stability comparing with conventional ones. Thus, this synthetic strategy offers a straightforward and convenient access to mesoporous aluminosilicates with zeolite-like acidity and stability.     

Artificial realization of human on-off decision making based on the conditional probability of a database

As human on-off decisions are the basic problems in our human lives, the analysis of human on-off decision making is an interesting topic. The procedures of qualified human decision making include many intuitive factors which have been acquired from previous valuable experience and gained through learning, but they may not be easily understood by others within a short period. By the use of a database of causes and decisions made by qualified experts for an objective event, human decision making for that event can be realizable artificially. This paper investigates a general method for realizing artificial human on-off decision making based on the conditional probability of the database. As on-off decision making is a discrete event and the causes for that decision making are continuous events, a mathematical treatment of a Dirac delta function in a probability density function is required to derive the conditional probability for the decision making. Several examples of artificial human decision making by the proposed method were demonstrated, and the results obtained showed good agreement with those of human experts in the respective fields. This work was presented, in part, at the Fourth International Symposium on Artifical Life and Robotics, Oita, Japan, January 19–22, 1999     

Automated Calibration of Robot Coordinates for Reconfigurable Assembly Systems

To achieve higher reconfigurability of an assembly line, quick plug-in and plug-out of devices such as robots is essential. When a new device is installed into the assembly line, calibration should be made. This research deals with an automated calibration system of relative position/orientation based on the Direct Linear Transformation method using two CCD cameras. The cameras are freely positioned, and then a set of motions is commanded to each manipulator. By detecting the motion with the cameras, the relative position of the two robots is obtained. The resultant accuracy is 0.16 mm rms at the best.     

Ultrastructural organization of the transverse tubules and the sarcoplasmic reticulum in a fish sound-producing muscle

The ultrastructural basis for the extremely rapid contraction-relaxation cycle (up to 300 s(-1)) in the swim-bladder muscle (SBM) of a scorpionfish (Sebastiscus marmoratus), producing characteristic sounds for communication, was investigated by electron microscopy. The SBM fibres contained well-developed sarcoplasmic reticulum (SR) showing triadic contacts with well-organized transverse tubules (T tubules). It was newly found that different types of triadic contacts were present within the single SBM fibre. In the middle region of the fibre (approximately 54% of the fibre length), the triadic contacts were located around the level of boundary between the A- and I-bands (AI-type triad). However in the two end regions of the fibre (approximately 21% and approximately 12% of the fibre length), the triadic contacts were seen around the level of the Z-band (Z-type triad). Between the middle and end regions of the fibre, T tubule-SR contacts exhibited the form of pentads composed of a pair of T tubules and three SR elements, and newly found heptads composed of three T tubules and four SR elements. The fractional volume of SR relative to the fibre volume was estimated to be approximately 26% in the middle region of the fibre with the AI-type triads and approximately 15% in the fibre ends with the Z-type triads. These results are discussed in connection with the mechanism, by which the mechanical activity of the SBM muscle is neurally controlled.