Influence of anions on the formation of β-FeOOH rusts

The artificial β-FeOOH rusts were synthesized by oxidation of FeCl₂ solutions and hydrolysis of FeCl₃ solutions. Various Na salts such as sulfate, biphosphate, nitrate, and silicate were added to the starting solutions at different anion/Fe molar ratios of 0-0.05. The XRD patterns of the products showed only the diffraction peaks of β-FeOOH. The crystallinity of the products was noticeably reduced by adding and but slightly influenced by adding . The addition of markedly crystallized the products by the hydrolysis of FeCl₃. The N₂ adsorption revealed that the products with were porous particles assembled by β-FeOOH subcrystals. and strongly coordinating to Fe(III) markedly lowered the crystallinity of the products and remained in the formed particles.     

Effects of sintering additives on dispersion properties of Al2O3 slurry containing polyacrylic acid dispersant

The effects of sintering aid adsorption on the dispersion properties of aluminum oxide slurries were investigated. We considered Al₂O₃ slurry without additives and Al₂O₃ slurry with a Mg additive with 0.1 mass% in oxide equivalent as a sintering aid. In this study, we evaluated the adsorption isotherm of polyacrylic acid (PAA) onto Al₂O₃ and the dispersion degree of Al₂O₃ slurries in sedimentation tests under gravity. The adsorption isotherm featured a characteristic adsorption isothermal line with a maximum value when Mg additive was present in Al₂O₃. In addition, the packing fractions did not correspond to the apparent viscosity. However, in slurry that was allowed to settle for several days, both of them agreed.Therefore, the disagreement between the packing fraction and the apparent viscosity immediately after preparation arose from changes of the dispersion state, such as the decrease of the distance between particles with time.     

Structure Modification of Alloy Solidified With Electromagnetic Field

A S45C carbon steel has been solidified under different electromagnetic conditions to investigate the effect of the electromagnetic force imposition and its imposing period on the solidified structure in this study.For excitation of the electromagnetic force,a static magnetic field and a direct electric current were simultaneously imposed on a sample under a certain period of the solidification.After the solidification,the microstructures were observed and compared each other.As the results,microstructure of the S45C steel under the simultaneous imposition of a static magnetic field of 1T and a direct electric current of 20A in the latter stage of its solidification was dendritic while it was globular if the electromagnetic force was imposed during the whole solidification period.     

Internal reforming characteristics of cermet supported solid oxide fuel cell using yttria stabilized zirconia fed with partially reformed methane

In order to investigate the internal reforming characteristics in a cermet supported solid oxide fuel cell (SOFC) using YSZ as the electrolyte, the concentration profiles of the gaseous species along the gas flow direction in the anode were measured. Partially reformed methane using a pre-reformer kept at a constant temperature is supplied to the center of the cell which is operated with a seal-less structure at the gas outlet. The anode gas is sucked in via silica capillaries to the initially evacuated gas tanks. The process is simultaneously carried out using five sampling ports. The sampled gas is analyzed by a gas chromatograph. Most of the measurements are made at the cell temperature (T_cell) of 750 °C and at various temperatures of the pre-reformer (T_ref) with various fuel utilizations (U_f) of the cell. The composition of the fuel at the inlet of the anode was confirmed to be almost the same as that theoretically calculated assuming equilibrium at the temperature of the pre-reformer. The effect of internal reforming in the anode is clearly observed as a steady decrease in the methane concentration along the flow axis. The effect of the water-gas shift reaction is also observed as a decrease in the CO₂ concentration and an increase of CO concentration around the gas inlet region, as the water-gas shift reaction inversely proceeds when T_cell is higher than T_ref. The diffusion of nitrogen from the seal-less outermost edge is observed, and the diffusion is confirmed to be more significant as U_f decreases. The observations are compared with the results obtained by the SOFC supported by lanthanum gallate electrolyte. With respect to the internal reforming performance, the cell investigated here is found to be more effective when compared to the previously reported electrolyte supported cell.     

A novel flavin adenine dinucleotide (FAD) containing d-lactate dehydrogenase from the thermoacidophilic crenarchaeota Sulfolobus tokodaii strain 7: purification, characterization and expression in Escherichia coli

Dye-linked D-lactate dehydrogenase activity was found in the crude extract of a continental thermoacidophilic crenarchaeota, Sulfolobus tokodaii strain 7, and was purified 375-fold through four sequential chromatography steps. With a molecular mass of about 93 kDa, this enzyme was a homodimer comprised of identical subunits with molecular masses of about 48 kDa. The enzyme retained its full activity after incubation at 80 degrees C for 10 min and after incubation at pHs ranging from 6.5 to 10.0 for 30 min at 50 degrees C. The preferred substrate for this enzyme was D-lactate, with 2,6-dichloroindophenol serving as the electron acceptor. Using high-performance liquid chromatography (HPLC), the enzyme's prosthetic group was determined to be flavin adenine dinucleotide (FAD). Its N-terminal amino acid sequence was MLEGIEYSQGEEREDFVGFKIKPKI. Using that sequence and previously reported genome information, the gene encoding the enzyme (ST0649) was identified. It was subsequently cloned and expressed in Escherichia coli and found to encode a polypeptide of 440 amino acids with a calculated molecular weight of 49,715. The amino acid sequence of this dye-linked D-lactate dehydrogenase showed higher homology (39% identity) with that of a glycolate oxidase subunit homologue from Archaeoglobus fulgidus, but less similarity (32% identity) to D-lactate dehydrogenase from A. fulgidus. Taken together, our findings indicate that the dye-linked D-lactate dehydrogenase from S. tokodaii is a novel type of FAD containing D-lactate dehydrogenase.     

Fuzzy-chaos hybrid controller for controlling of nonlinear systems

A novel concept for controlling of nonlinear systems using chaos and fuzzy model-based regulators is presented. In the control of such systems, we employ two phases, the first of which uses open-loop control forming a chaotic attractor or using chaotic inherent features in a system itself. Once the system states reach a predefined convex domain, open-loop control is cut off and a fuzzy model-based controller is employed under state feedback control in the second phase. The relaxed stability conditions and linear matrix inequalities (LMIs)-based design for a fuzzy regulator is introduced to construct a fuzzy attractive domain, in which a global solution is obtained so as to achieve the desired stability condition of the closed-loop system. The proposed controller architecture has been tested using three nonlinear systems: the Henon map, the Lorenz attractor, and a two-link manipulator. The simulation results show the effectiveness of the proposed controller     

Neural network based expectation learning in perception control: learning and control with unreliable sensory system

In this article, we investigate the viability of our proposed neural network-based extension of the perception control concept introduced by Randløv and Alstrøm. In their work, each of the expectation elements is linearly acquired such that the expectation gives only the dominant information of the recent past. This handicap could become a serious problem when the perception process is applied to real physical systems. Such an approach has no capability to sense the trend or the dynamics in the information. Here, we introduce an extension of the perception control process by using a radial basis function feedforward neural network to learn the trend and the dynamics in the information queue. Through our simulations, we show that our neural network-based method is better than the conventional method.This work was presented, in part, at the 8th International Symposium on Artificial Life and Robotics, Oita, Japan, January 24–26, 2003     

Relaxation behavior of polymers probed by positron annihilation lifetime spectroscopy

Relaxation behaviors of polyethylene, polypropylene, and polycarbonate have been studied by positron annihilation lifetime spectroscopy (PALS). In PALS positron sources made of radioisotopes are used to inject positrons into polymer as a micro probe. The injected positron probes can induce radiation effect, which plays an important role in detecting the polymer relaxation behavior through electrons trapped in shallow potentials at low temperature. Monitoring the intensity (I₃) of ortho-positronium (o-Ps), transitions of γ and δ relaxation can be measured by PALS as a secondary effect. In this experiment, the change of I₃ below Tg is connected with the number of the trapped electrons, which can be excited from the shallow potential by the thermal motion of polymer structures and visible light irradiation. In the PALS measurements of non-irradiated PP samples, relaxation of methyl groups was observed as low as 50 K, which can be assigned as the δ relaxation. Relaxations of β and γ were also observed for the non-irradiated PP samples between 100–370 K. However for the 3 MGy γ-ray irradiated PP samples, only β relaxation was observed because the large radiation dose caused a large number of scissions of –CH₃ groups from main chains and the characteristics changed. For the irradiated samples, radiation hardening was observed. Electronic Publication