Copper-bearing dross generated in lead metal smelting operations is composed of very complex compounds which include Pb, Sn and Sb. The presence of these elements makes the dross difficult to process. The copper compounds also include valuable metals and rare earth elements, therefore an efficient refining technology is required. In previous works, we have shown that evaluating the dross phases by using both fast Silicon drift detector technology (Thermo Scientific UltraDry) and multivariate statistical component analysis (Thermo Scientific COMPASS) is very effective. In this work, we investigated the refining heat treatment conditions in the process of the copper-bearing dross. The results of the COMPASS phase analysis showed that a Cu-Sn alloy was the main copper-bearing phase generated in the dross when small amounts of oxygen were introduced during the heat treatment process. Conversely, under high oxygen conditions during the process CuO is generated as the principal copper-bearing dross component. The leaching rate of Cu was about 50% after sulfuric acid leaching for the unprocessed dross. The leaching rate of Cu increased to more than 95% for the processed dross in which the principal component was CuO. Using these analysis results, we were able to rapidly and accurately determine the efficiency improvement of the copper refining process.
Superconducting current leads have been prepared by the TFA-MOD processed YBCO tapes. YBCO tape is 5 mm in width, and about 120 µm in thickness. The YBCO superconducting layer, 1.5 µm in thickness, is formed on oxide buffer layers of GZO and CeO2 deposited on HastelloyTM substrate tapes. Transport current is supplied through Ag layer deposited on YBCO layers. Current leads No.1 and No.2 have been composed of 20 YBCO tapes soldered to Cu caps at both ends. The two stainless steel boards as the shunt have been attached to current lead at both sides. The YBCO tapes with critical current of about 80 A (current lead No.1) and 61 A (current lead No.2) at 77 K in self-field have been used for current lead No.1 and No.2, respectively. The transport current of 1,600 A in current lead No.1 and 1,200 A in current lead No.2 were stably carried in liquid nitrogen without any voltage appearance on each tapes. The heat leakage of current leads No.1 and No.2 composed of 20 YBCO tapes, two stainless steel boards and GFRP board between 77 K and 4.2 K is calculated to be 547 mW (342 mW/kA : current lead No.1), 535 mW (446 mW/kA : current lead No.2), which is much smaller than that of conventional Cu current lead (1.2 W/kA). The small heat leakage results from high current performance and low thermal conductivity in the present superconducting current leads.
MgB2 wires have been prepared by diffusion process using pure Mg metal tube. Amorphous B powder mixed with 5 mol% SiC nano-sized powder addition was encased in a Mg tube, and then the tube was inserted into a pure iron tube to form the Fe/Mg/B(powder) composite wires. The composite was drawn into around wires of 1.0 ~ 0.8 mm in diameter without intermediate annealing. The composite wires were heat treated at 630 °C for 5 h in Ar gas atmosphere. Some of the specimens were hot-pressed under 10 MPa during heat treatment. The MgB2 core was synthesized through the diffusion reaction between outside Mg metal tube and inside B powder with SiC addition. The MgB2 core forms denser structure without voids and cracks in comparison with conventional in-situ PIT processed MgB2 wires. The Ic values at 4.2 K for the MgB2 wire of 1.0 mm and 0.8 mm in diameter reaches to 134 A and 187 A at 5 T ,which corresponds to the Jc of 2230 A/mm2 and 3740 A/mm2, respectively. The Ic of the hot-pressed wire is 164 A at 5 T.
A novel drug-injection system that utilities direct chemo-mechanical energy conversion was fabricated and demonstrated for feedback control of glucose level. The system consists of two integrated units, decompression unit and drug release unit. The decompression unit was fabricated by separating a cylindrical cell into a top cell (gas phase) and a bottom cell (liquid phase) by glucose oxidase (GOD) enzyme immobilized membrane. The enzyme membrane recognizes glucose and converts chemical energy into pressure decreaese by consuming oxgen. The linear correlation between glucose concentration and de-pressure slope of the top cell was revealed as applying glucose solution to the bottom cell. The drug release unit which utilizes the energy of the decompression unit as a power source was evaluated by recording its release actions. The system is expected to be used in intelligent actuators without external energy.
A flexible alcohol sensor using functional polymers for transcutaneous bioinstrumentation was constructed and tested. The sensor was composed of a flexible electrode and an enzyme membrane. In the fabrication process of the electrode, Pt and Ag/AgCl electrodes were formed onto a PDMS membrane by MEMS technique. In the enzyme immobilization, a mixture solution of alcohol oxidase and photocrosslinkable polyvinyl alcohol was spread onto a PTFE membrane. The AOD was immobilized by ultraviolet irradiation. The enzyme membrane was attached to the sensing region of the electrode with biocompatible polymer. In the characteristic evaluations, the sensor was dipped into a phosphate buffer, and then a potential of +400 mV (vs. Ag/AgCl electrode) was applied to Pt-working electrode. The change of the output current by dropping of ethanol solutions was measured with PC. As a result of the evaluation, the output current rapidly increased immediately after the dropping of alcohol solutions and then was stable within 60 seconds. The output current linearly corresponded to alcohol concentrations over a range of 0.001-7.0 mmol/l, with a correlation coefficient of 0.999.
We are studying the neutron production regime in IECF (inertial electrostatic confinement fusion) device. Fusion reactions are mainly occurred both beam-background and fast neutral-background reaction in IECF device. The cross section of D-D reaction increases with incident deuteron’s energy. If the reaction occurs only from beam-background channel, generated neutrons will dominate near the cathode. Two 3He proportional counters which are in lengthwise and lateral positions were used to measure neutron counts. The results showed neutrons were produced via not only beam-background channel but also fast neutral-background channel.