Preconcentration of trace elements by adsorption onto a niobium wire for electrothermal atomization atomic absorption spectrometry with a tungsten tube atomizer

In the present work, a new preconcentration method of trace elements by adsorption onto a niobium wire has been developed for electrothermal atomization atomic absorption spectrometry (ETAAS) with a tungsten tube atomizer. Detection limits (pg·mL^–1) by this method combined with ETAAS were 45 for bismuth, 7.0 for cadmium, 20 for copper, 1.3 for gold, 36 for lead, 65 for manganese, 9.5 for rhodium and 19 for silver.     

Electrochemically assisted room-temperature crack healing of ceramic-based composites

We demonstrated for the first time the room-temperature crack healing in ceramic-based composites. For this purpose, 20 and 30 vol% of fine titanium metal (Ti) were homogeneously dispersed in electrically insulating alumina (Al₂O₃) ceramic to obtain composites that exhibited excellent electrical conductivity. Electrochemical anodization at room temperature was used to successfully heal cracks induced in the Al₂O₃/Ti composites and recover their fracture strength and reliability. The bending strength of as-prepared, crack-induced, and electrochemically healed composites was measured to evaluate the crack-healing ability. Moreover, the effects of the anodization current density, crack size (including length and crack open distance), and the conductivity of the composites on their crack-healing behavior were investigated and discussed. The results indicate that the bending strength of crack-induced composites, which was approximately 61% of the crack-free composite strength, was completely recovered after the crack-healing procedure at room temperature under appropriate anodization conditions. The titanium oxides obtained after anodization formed bridges that healed the crack; this was considered to be the main strength recovery mechanism. By anodizing Al₂O₃/Ti composites, we developed a new and convenient approach to heal cracks and recover the fracture strength of cracked ceramics at room temperature.     

Effect of crystallographic orientation on transparency of alumina prepared using magnetic alignment and SPS

Transparent polycrystalline alumina was developed over many years because its attractive properties are expected to find applications in many fields. Crystallographic orientation is one of the effective ways to improve transparency in birefringent ceramics such as alumina, because birefringence at grain boundaries can be suppressed by the alignment of optical axis. Fabrication of high-transparency alumina with an oriented c-axis and fine microstructure can be attained by slip casting in a strong magnetic field, followed by spark plasma sintering at 1150?°C for 20?min. The real in-line transmittance of the textured alumina with a thickness of 0.80?mm was 70% at λ?=?640?nm, which was higher than that of randomly-oriented alumina. The c-axis orientation reduced the actual difference of the refractive index and suppressed remarkably the birefringence.     

Manufacturing Nano-Diphasic Materials from Natural Dolomite: In Situ Observation of Nanophase Formation Behavior

Decomposition of the mixed carbonate mineral dolomite, CaMg(CO₃)₂, and formation of CaO/MgO nanopolycrystals were observed in situ using a field emission scanning electron microscope with a hot stage. The pyrolysis behavior of dolomite was studied with an in situ high–temperature X–ray powder diffraction technique. Nano–sized particles formed during pyrolysis then sintered into CaO/MgO nanopolycrystals. Dense bulk–form CaO/MgO and CaZrO₃/MgO nanocomposites were successfully fabricated using reactive hot–pressing from dolomite and dolomite/zirconia mixed powders, respectively.     

Preparation of poly(2-pyridone-3,5-diyl)s with –(CH2)4–SO3M (M = H or Na) side chains

Poly(2-pyridone-3,5-diyl)s with –(CH₂)₄–SO₃M (M = H or Na) side chains have been prepared by nickel-complex promoted dehalogenative polycondensation. A composite film of the polymer with –(CH₂)₄–SO₃H side chains and poly(vinyl alcohol) showed a proton conductivity of 1.5 × 10^?1 S cm^?1 at 80 °C and 95% humidity. A copolymer with pyridine showed a high stability against oxidation by a Fenton reagent.     

Development of fully-automated synthesis systems

This paper describes the development of fully-automated synthesis systems for preparing and isolating various kinds of pharmaceutical compounds. The systems are versatile, and are able to perform most of the chemical reactions currently used in organic chemistry, with the exception of hydrogenation which requires high pressure. An additional benefit is the very user-friendly software.     

Processing-Dependent Microstructural Factors Affecting Cavitation Damage and Tensile Ductility in a Superplastic Alumina Dispersed with Zirconia

Superplastic tensile ductility in Al₂O₃–10 vol% ZrO₂ (3 mol% Y₂O₃) exhibits processing dependence when the grain size is reduced to 0.45 μm for a given relative density of ∼99.5%. The reduced grain size leads to largely enhanced ductility in a material prepared by colloidal processing, but does not in a material prepared by conventional dry processing. This result is explained from cavity-damage accumulation sensitive to a rather small variation in a few processing-dependent factors: the numerical densities of residual defects and ZrO₂ particles. The rate of damage accumulation is shown to depend mainly on the former and additionally on the latter.     

The development of pivot bearing with multiple degrees of freedom: 2nd Report: Prototype of pivot bearing with three degrees of freedom

In this paper, we report a prototype of a new pivot bearing having three degrees of freedom. The idea of the pivot bearing is based on a constant velocity joint (CVJ). In the first report, two types of pivot bearing were designed and produced. Then, the static performance was examined. In this second paper, we have achieved three degrees of freedom by adding a ball bearing mechanism. However, this bearing with three degrees of freedom was larger than the bearing with two degrees of freedom. Then, in order to improve the internal structure, a full complement ball bearing was applied. Thus, the size of the bearing with three degrees of freedom was conformed to the bearing with two degrees of freedom. Furthermore, process accuracy was evaluated.     

Composition measurement of paraelectric SrTiO3 layer

Abstract

Since composition is an important parameter affecting the dielectric properties in paraelectric SrTiO₃ layers, composition is determined by Rutherford backscattering spectrometry (RBS) measurement. In this measurement, specifically for achieving precise composition measurement, the RBS spectra of Sr, Ti and O must be separated individually. This spectrum separation can only be attained when thin (800 A[ddot] thick) Sr_xTiO_y layers are deposited on graphite substrate. The measurement is performed for layers deposited at different O₂ partial pressure ratios and sputtering pressures. This measurement indicates that composition of O, y, in Sr_xTiO_y layer decreases from 3.7 to 2.7 with the decrease of O₂ partial pressure raito, R(=O₂/O₂ + Ar) from 1.0 to 0.83. Composition of Sr, x, also changes from 1.1 to 0.6 with this change. With the decrease of sputtering pressure from 10 to 5 mTorr, however, composition, y, is held at 2.7 and only the composition, x, increases from 0.6 to 1.1. This composition measurement is useful for the deposition of optimized dielectric layer employed in the charge storage capacitor.