Fabrication and evaluation of various types of micro one-way valves through micro rubber molding process

In recent years, research and development on micro fluid systems has become active in the fields of chemical technology and biotechnology. For the realization of these micro fluid systems, micro fluid devices such as micro-valves and micro pumps are very important. This paper reports the fabrication and experimental evaluation of several micro one-way valves. The valves are fabricated through a micro molding process, which makes the fabrication process simple and suitable for mass production. The experimental results indicate that the developed valve has great performance with a normal flow rate of 130.2 ml/min and a leak flow of 2.2 ml/min. The normal flow rate is 1.4 times higher than that of the previous model.     

Mass Production of High-Purity Iron Using Anion-Exchange Separation and Plasma Arc Melting

High-purity Fe was manufactured using anion-exchange separation (AES), oxidation refining, and hydrogen-argon plasma arc melting. As a result, the purity of Fe achieved 99.9993 mass pct. Two issues have been improved: the decrease in the refining efficiency in AES was solved by the decrease in the flow rate, and W contamination during plasma arc melting was solved by the increase in the cooling efficiency of W-ThO₂ cathode.     

Drying behavior of sludge with drying accelerator

Abstract

For fuelization of high moisture content sludge, efficient sludge drying technique using a drying accelerator was investigated. In the experiment, drying accelerator types and drying conditions were changed and the effect of accelerator type and/or drying condition on sludge drying behavior was evaluated by analyzing drying characteristic curve. Depending on drying accelerator type, the addition of drying accelerator did not always exert superiority in drying rate, but sludge with added acrylic resin having low glass transition temperature (DA10) demonstrated significantly enhanced drying rate. Addition of surface activating agent (SAA) instead of resin type drying accelerator also enhanced the sludge drying rate. The highest drying rate was obtained by addition of DA10 and SAA together, and the sludge drying rate has significantly been augmented at the high drying temperature condition.     

Effective catalyst on SiO2 in ethanol CVD for growth of single-walled carbon nanotubes

We have compared catalytic activity of Co and Fe in a growth process of single-walled carbon nanotube (SWNT) by chemical vapor deposition using ethanol as a carbon source and SiO₂ as a catalyst-supporting material. Changes of the catalyst precursors (Co- and Fe acetate) in the growth process were carefully observed at three different stages: (i) after oxidation in air at 400 °C but before heating to the growth temperature (800 °C), (ii) after heating to the growth temperature in flowing Ar and H₂ but before starting the nanotube growth and (iii) after the growth process is over. During the growth of SWNT, the Co catalyst took the form of β-Co, resulting in a high yield growth. On the contrary, the Fe catalyst formed a silicate, Fe₂SiO₄, showing a poor catalytic ability. Our result shows that chemical reactions between the catalyst precursors and their supporting materials sensitively affect the catalytic ability.     

Anomalous Resonance Phenomena in Two-Dimensional Electrons on the Surface of 3He-4He Liquid Mixtures

No Heading We report on anomalous resonance phenomena observed in a two-dimensional electron system on ³He-⁴He liquid mixtures. The resonance is observed in a Corbino conductivity measurement, in which a magnetic field B is applied prependicular to the electron sheet. We have detected the resonances for ³He concentrations n₂ from 0.475% to 10.20%, and at temperatures below 800 mK. The resonance frequency f_r is inversely proportional to B. In a preliminary study we found that f_r and the resonance amplitude increases when the electron sheet is not parallel to the electrode, and this made the understanding difficult. Here we have made the systematic measurement keeping the parallelism between the electrons and the electrode. We have observed the resonance only at n₃ > 0.475%. This fact finally leads us to conclude that adding ³He atoms to liquid ⁴He induces the nonuniformity in local electron density, and hence the resonance.PACS numbers: 73.20.–r, 67.60.–g     

Morphology and electrical conductivity of injection-molded polypropylene/carbon black composites with addition of high-density polyethylene

This work attempts to clarify the influence of carbon black (CB) addition on the microstructure of injection-molded high-density polyethylene (HDPE)/polypropylene (PP) blends and effect of shear-induced polymer deformation on the conductive network structure. We observed that HDPE molecules are strongly interacted with carbon surfaces and CB particles are selectively located in HDPE domains. Morphology of the injection-molded specimen consists of three parts, namely, CB-HDPE complex domain, free HDPE domain and PP domain. The volume and microstructure of the free HDPE domain are significantly influenced by HDPE and CB concentration, CB structure, and PP viscosity. We also confirmed that the CB particles are capable of self-assembly to form random conductive networks even under high shear rate within very short time. The morphological changes were finally correlated to the variation of electrical conductivity.     

A study of the initial oxidation of copper in 0.1 MPa oxygen and the effect of purity by metallographic methods

To clarify the initial oxidation mechanism of copper, the oxidation was carried out at 400 °C in 0.1 MPa oxygen using 99.9999% (6 N) and 99.5% (2 N) pure specimens. Oxidation of 6 N copper after 60 s showed that the number density of the oxide nuclei varied with the face of copper crystals, while the nucleation occurred preferentially at the grain boundaries. A metallographic examination indicated that the products of initial oxidation consist of both CuO and Cu₂O. CuO is firstly formed as a thin uniform film on the copper surface, and then Cu₂O nucleates and grows beneath the CuO film. This result is different from the conclusion reached in the literature that CuO does not appear until the laterally growing Cu₂O nuclei have covered the whole surface using other methods. In contrast to 6 N copper, nucleation of Cu₂O was much delayed for 2 N copper, though a thin CuO film was similarly formed on 2 N copper surface. Impurities in 2 N copper should be responsible for slow nucleation of Cu₂O and slow growth of nuclei.