Supercritical fluid extraction of fungal oil using CO2, N2O,CHF3 and SF6

The extraction of oil from fungi (Mortierella ramanniana var.angulispora) was studied using carbon dioxide (CO₂), nitrous oxide (N₂O), trifluoromethane (CHF₃) and sulfur hexafluoride (SF₆) under supercritical conditions. The oil solubility was highest in SC-N₂O followed by SC-CO₂, while both SC-CHF₃ and SC-SF₆ showed poorer solvent power. The recorded oil solubilities at 333 K and 24.5 MPa were 2.3 wt% in N₂O, 0.48 wt% in CO₂, 0.0099 wt% in CHF₃ and 0.0012 wt% in SF₆. The oil solubilities in SC-N₂O and SC-CO₂ were measured over the pressure range 15.7–29.4 MPa and at temperatures ranging from 313–353 K. N₂O always showed greater solvent power than did CO₂ at the same temperature and pressure. The solvent power of a supercritical fluid increases with density at a given temperature, and increases with temperature at constant density. The change in neutral lipid composition of the extracted oil with the extraction ratio was measured. Free fatty acids or diglycerides were extracted more easily than triglycerides or sterol esters. The change in fatty acid composition was also measured. The proportion of γ-linolenic acid in the extract remained constant throughout the extraction.     

A Low-Loss Built-In Current Sensor

This paper presents a novel built-in current sensor that uses two additional power supply voltages besides the system power supply voltage, and that is constructed by using a current mirror circuit to pick up an abnormal IDDQ. It is activated only by an abnormal quiescent power supply current and minimizes the voltage drop at the terminal of the circuit under test. Simulation results showed that it could detect 16-A IDDQ against 0.03-V voltage drop at 3.3-V VDD and that it reduced performance degradation in the circuit under test. It is therefore suitable for testing low-voltage integrated circuits. Moreover, we verified the behavior of the sensor circuit implemented on the board by using discrete devices. Experimental results showed that the real circuit of the sensor functioned properly.     

Hydrothermal epitaxy of KTaO3 thin films under supercritical water conditions

Potassium tantalate powders were hydrothermally synthesized at 400 °C using Ta₂O₅ and KOH as starting materials with various KOH concentrations (0.1–1.0 M) and heating durations (2–48 h). A defect pyrochlore phase of KTa₂O₅(OH)·nH₂O, was obtained at low KOH concentration and short reaction time. The perovskite phase of KTaO₃ predominated as the heating duration and the KOH concentration increased. Pure KTaO₃ was obtained in 0.5–1.0 M KOH aqueous solutions and reaction times of 8–48 h. Heteroepitaxitial KTaO₃ thin films were achieved on the (100) SrTiO₃ substrate in 0.5 M KOH solution under supercritical water conditions. Based on the XRD, SEM-EDX and EBSP (Electron BackScatter Pattern) results, epitaxial KTaO₃ crystals were grown on the (100) oriented single-crystal SrTiO₃ substrate. Synthesis of perovskite KTaO₃ crystals in supercritical water employed significantly low KOH concentrations (<0.5 M), which was far less than the very high concentrations (>7 M) required for conventional hydrothermal method.     

Sludge depositions in a long tube-high flow MSF test plant

During the operation of a multistage flash (MSF) evaporation plant, a rather rapid decrease was observed in the economy ratio of the plant when the dissolved oxygen (DO) content of the circulating brine was at a high level. This phenomenon was brought about by the reduction of heat transfer coefficients of condenser tubes due to sludge formation on the inside tube surface by the co-precipitation of ferric hydrous oxide with silica, alumina, and organic materials. The chemical analysis of the sludge and circulating brine showed a close relationship to DO values in the brine, the concentration of iron in the sludge, and the decreasing value of the heat transfer coefficient. The lowering of DO was found very effective for avoiding the sludge trouble.     

Concentration of heavy water in seawater distillation process

Distributions of deuterium in two multi-stage flash plants and a multi-effect plant were calculated by use of a numerical model. The calculated values were in good agreement with the observed ones. The maximum error was less than 1%. Product water of high deuterium concentration can be obtained from the distillation chamber at the highest temperature with a high concentration factor. The deuterium concentration in the product water was around 155 ppm.     

Kinetics of the catalytic decomposition of hydrogen iodide in the thermochemical hydrogen production

The decomposition rates of hydrogen iodide over platinum supported γ-alumina were measured in the range from 480 to 700 K by the use of a flow method. It was found that Pt/γ-alumina catalyst was effective for the decomposition of hydrogen iodide. According to the Langmuir-Hinshelwood model, an overall rate equation was obtained on the basis of the mechanism where the rate-determining step was a surface reaction. Experimental data were well correlated with the rate equation.     

Adaptive Fault Diagnosis of Analog Circuits by Operation-Region Model and X–Y Zoning Method

We have proposed a method for diagnosing analog circuits that is realized by combining the operation-region model and the X–Y zoning method. In the method, we could implement a diagnosis procedure based on a diagnostic method for digital circuits because we developed a data processing method to handle data discretely. In this paper, we improve the method by using an adaptive test to obtain a shorter diagnostic sequence length and show its characteristics. Moreover, we propose a new data processing method that utilizes the output response of a circuit to obtain better diagnostic performance. We demonstrate the effectiveness of the proposed methods by applying them to ITC’97 benchmark circuits with hard faults and soft faults. These improved methods can reduce the diagnostic sequence length without degrading the performance of diagnostic resolution and CPU time.     

The study of the effect of external additives on the synthesis of fumed TiO2 with a high content of rutile structure by the novel natural dropping thermal treatment

The effect of external additives on the synthesis of fumed TiO₂ with a high rutile structure content was studied. The focus of this investigation was on the external additive species, agglomerates of the fumed TiO₂ before and after the thermal treatment. The transformation ratio from the anatase to rutile structure of the thermally-treated fumed TiO₂ was investigated as a function of the fumed TiO₂ agglomerate before the thermal treatment. Small agglomerated powders resulted in a decrease of transformation temperature. Two novel results were obtained in this investigation. One was a new fumed TiO₂ with a 100% rutile structure having an excellent dispersibility being successfully synthesized by the thermal treatment of AEROXIDE® TiO₂ P 25 with a small portion of AEROSIL® R 972. The other was the remarkable acceleration of the transformation from the anatase to rutile structure and grain growth/sintering of the thermally-treated fumed TiO₂ observed at a relatively low thermal treatment temperature by the oxidation reaction of calcium stearate as an external additive.