Increase in the number of acid sites of a H-ZSM5 zeolite during the dehydration of ethanol

The activity of a H-ZSM5-90 for the dehydration of ethanol at 473 K increased with an increase in time on stream. The results of NH₃-TPD and Ar adsorption showed that the number of acid sites of the H-ZSM5-90 increased during the dehydration. On the other hand, the activity and the number of acid sites of H-mordenite-90 were almost unchanged during the dehydration. Since the pre-treatment of the H-ZSM5-90 with ethylene at 473 K largely increased its activity for the dehydration of ethanol, it is suggested that a large number of new acid sites could be formed inside the pores of H-ZSM5-90 via the polymerization of ethylene produced by the dehydration of ethanol.     

Poly(p-substituted phenylacetylene) with perfluoroalkyloxydimethylsilyl side groups for oxygen and ethanol permselective membrane

Summary p-(1H,1H,2H,2H-perfluorodecyloxydimethylsilyl)phenylacetylene(ACf8) and p-(1H,1H,2H,2H-Perfluorohexyloxydimethylsilyl)phenylacetylene(ACf4) were synthesized and copolymerized with p-trimethylsilylphenylacetylene(ASi). The resulting copolymers, copoly(ACf8/ASi) and copoly(ACf4/ASi), were fabricated to tough membranes showing high oxygen permeabilities(Po ₂) of 10^-8 cc(STP)·cm/cm²·s·cmHg and high oxygen permselectivities(=Po ₂/Pn ₂) of more than 2.7. In particular, a copoly(ACf4/ASi) containing 15.1 mol% of ACf4 unit showed the best result: Po ₂=3.51x10^-8 cc(STP)·cm/cm²·s·cmHg and =3.04. The values were in a top level and very close to those of upper bound line in an -Po ₂ plot of data in the literature. In addition, copoly(ACfn/ASi) membranes were ethanol permselective owing to water repellency of the perfluoroalkyl groups. Copoly(ACf4/ASi) membranes showed better oxygen and ethanol permselectivity than copoly(ACf8/ASi) membranes.     

Graft polymerization of triethoxyvinylsilane–styrene and triethoxyvinylsilane–methyl methacrylate binary monomers onto various silicates

Triethoxyvinylsilane–styrene and triethoxyvinylsilane–methyl methacrylate binary monomers were polymerized by chemical initiation or by γ-ray irradiation in the presence of silica gel, fire brick, quartz wool, and glass beads. The amount and composition of the polymers grafted to silicates were analyzed by using pyrolysis gas chromatography. When triethoxyvinylsilane alone was subjected to the reaction with silicates, condensation occurred irrespective of the initiating means, and the extent of the reaction was almost proportional to the specific surface area of the silicate. When binary monomer mixture was applied, incorporation of styrene or methyl methacrylate into the grafted polymer was observed whenever a monomer mixture of high styrene or methyl methacrylate content was submitted to the reaction. On each silicate, the relationship between the composition of polymer grafted on it and that of monomer showed a similar pattern in spite of the great difference of the specific surface area. Almost no participation of styrene or methyl methacrylate was observed when the silicate preirradiated in air or under vacuum was heated with the binary monomer mixture. It was concluded that triethoxyvinylsilane reacts with silicates by condensation and that some of the pendent vinyl groups on the silicates are incorporated into the copolymer with styrene or methyl methacrylate.     

Diffusion/adsorption model of cellulose dyeing. I. The diffusion through never-dry cellulose

The diffusion coefficients D₀, of C.I. Direct Yellow 12, Red 2, Blue 1, and Blue 15 in aqueous NaCl solution were measured at 90°C by the diaphagm cell method. The values of D₀ for Yellow 12 and Red 2 showed a salt concentration dependence and those for Blue 1 and Blue 15 were constant over the ionic strength range from 0.01 to 0.10. In the adsorption/diffusion models proposed so far for the direct dye–cellulose system, the Standing–Warwicker–Willis model was shown to be similar in principle to the Weisz–Zollinger model. The adsorption/diffusion behaviors in never-dry cellophane sheet for C.I. Direct Yellow 12 and Blue 15 were examined by the method of cylindrical film roll at 90°C. The concentration dependence of the apparent diffusion coefficient for these dyes showed an incomplete validity of both the models.     

3D Scan matching for mobile robot localization over rough terrain

In order to enable an autonomous mobile robot to travel over rough terrain, it necessitates the capability to detect self‐position accurately even when the odometry errors are increased in traveling. The conventional method can keep high speed and precise localization using iterative closest point algorithms or feature matching techniques. However, effects of steep changes of a mobile robot position are not considered when it travels over rough terrain. In this article, we propose the method for efficient real‐time 6D pose tracking using a rotating 2D laser scanner in traveling over rough terrain. For adaptation to steep changes of the position, weighted point clouds are generated based on the angular and the linear velocity measured by sensors mounted on the robot. And the position and posture of the robot are sequentially optimized by the scan matching in increments of 10 scans. In indoor experiments, we evaluated accuracy of our method when the robot passes on rugged floor. As a result, our method was performed with less than 0.078 m RMS positional error in real time.     

Spatial distributions of atmospheric concentrations of radionuclides on 15 March 2011 discharged by the Fukushima Dai-Ichi Nuclear Power Plant Accident estimated from NaI(Tl) pulse height distributions measured in Ibaraki Prefecture

ABSTRACT

A hybrid method for estimation of atmospheric concentrations of multiple radionuclides was developed and applied to NaI(Tl) pulse height records measured in Ibaraki Prefecture in the morning of 15 March 2011 when three radioactive plumes from the Fukushima Dai-Ichi Nuclear Power Plant Accident passed. The method is based on the simple principle for separation from deposited radionuclides’ contribution and the concentration estimation for multiple radionuclides. Difficulty in the concentration estimation due to complexity of surrounding terrains and geometry was overcome to obtain spatiotemporal variations in atmospheric concentrations of Xe-133, Te-132, I-131, I-132 and I-133 in the three plumes at 21 monitoring stations. The plume axis with higher I-131 concentration of 5.40 kBq m-3 than the previous estimations during the second plume was found in the northwestern inland area. A substantially lower Xe-133/I-131 concentration ratio of the first plume than those of the others was again recognized. The details of non-uniform spatial distribution of the radionuclide composition were found for each of the three plumes.     

Development of a new lapping method for high precision ball screw (1 report)-feasibility study of a prototyped lapping tool for automatic lapping process

Ball screws are being lapped as a finishing process to improve the travel variation, drunkenness and surface finish in order to provide high precision requirements in various mechanical applications. However, the existing manufacturing method is very labor intensive that needs a highly skilled machinist to perform the hand lapping operations using the conventional laps which have two or three slits. These types of lap cannot eliminate and improve the special components of drunkenness such as ellipsoidal, triangular and other polygonal cross sections. This paper presents a new lapping method to determine the technical and operational feasibility of a prototyped lapping tool with the combination of a flexible lap and polyurethane elastomer which can be mounted in the vertical-type automatic lapping machine. This new type lapping tool with six slits, is especially designed which each section can move in radial direction wherein the uniform lapping pressure is applied on the test piece from six directions. Based on experimental results, it showed that the travel variation was greatly reduced along with drunkenness and lapping time.     

Microstructure of a Complex Oxide, Er2Mn2/3Mo4/3O7, with a Pyrochlore-Related Structure

The ternary compound Er₂Mn_2/3Mo_4/3O₇, with a pyrochlore-related structure, was synthesized in a vacuum-sealed quartz tube at 1373 K. The compound was characterized by X-ray diffractometry, electron probe microanalysis, and transmission electron microscopy. The compound possessed a monoclinic structure, with lattice parameters of a = 1.2781(2) nm, b = 0.7378(5) nm, c = 1.1643(6) nm, and β= 100.53(1)°. The compound had a large number of lamellar domains, which were composed of a microtwinned structure on the twin axis 〈1¯1¯0〉.