Layered mixed-anion compounds: Epitaxial growth,active function exploration,and device application

Optoelectronic properties and device applications of layered mixed-anion compounds such as oxychalcogenide LaCuOCh (Ch = chalcogen) and oxypnictide LaT_MOPn (T_M = 3d transition metal, Pn = pnicogen) are reviewed. Several distinctive functions have been found in these materials based on our original material exploration concept. Fabrication of high-quality epitaxial films of LaCuOCh leads to clarifying the excellent electrical and optical properties such as high hole mobility of 8 cm²/(V s) and heavy hole doping at >10²¹ cm^?3 in LaCuOSe, and sharp and tunable-wavelength photoluminescence in the solid–solution systems in LaCuOCh. In addition, a room temperature operation of a light-emitting diode is demonstrated using LaCuOSe as a light-emitting layer. These results suggest that the layered oxychalcogenides have potential for light-emitting layers as well as transparent hole-injection layers in organic/inorganic light-emitting diodes. Furthermore, by extending the material system from the copper-based oxychalcogenides to isostructural compounds, transition metal-based oxypnictides LaT_MOP (T_M = Fe, Ni), we have found novel superconductors, LaFeOP and LaNiOP.     

Fundamental Behavior of Direct-Coupled Submicrosecond Pulse Energization in Electrostatic Precipitators

The fundamental characteristics of the direct-coupled pulse energization in electrostatic precipitators (EP's) are investigated in a test rig comprised of a coal pulverizing facility, a furnace, a gas cooling system, and an EP. The EP consisted of a corona electrode with barbed wires and a collection electrode with 300-mm duct spacing. This simulates the type of EP normally used in a coal-fired power station. The pulse-energized collection field shows a very high collection performance of more than 99 percent collection efficiency and the performance enhancement compared to the conventional dc energization, causing very severe back corona, becomes as large as H = 2.50.H is the enhancement factor in terms of the Deutsch migration velocity in the case of the very high resistivity dust of rd = 2 x 1013 ?cm at the gas temperature of Tg = 150°C. Even at the lower level of the dust resistivity at Tg = 110°C, where no back corona occurs in the dc-energized collection field, the performance enhancement is as large as H = 1.21. The mechanism of such great performance enhancement is likely to be the result of the very uniform and very intense formation of corona plasmas on the wires as a result of the very fast rise in the pulse voltage applied and a special sawtooth waveform of the operating voltage between the corona and collection electrodes.     

Evaluation of selective plating media for the detection of heat- or freeze-injured Staphylococcus aureus

The efficacy of Baird-Parker (BP) agar, mannitol-salt-egg yolk (MSEY) agar and mannitol salt (MS) agar in detecting Staphylococcus aureus FRI-100 heated at 52 degrees C for 20 min in 100 mmol/L potassium phosphate buffer was determined. Brain heart infusion agar with 1% pyruvate (BHIP agar) supported the highest recovery of injured cells and was used as the control medium. Of the three selective media, significantly higher recovery of heat-injured cells was observed on BP agar than MSEY agar, and the poorest recovery was observed on MS agar (p < 0.05). Low recovery of unheated cells was obtained for MS compared with other media (p < 0.05). A reduction in populations occurred gradually in reagent-grade water stored for 14 days at -20 degrees C. There was no significant difference between BHIP agar and MS agar in the number of freeze-injured cells recovered from 1 to 14 days.     

Measurement of mean free paths for inelastic electron scattering of Si and SiO2

The effects of accelerating voltage and collection angle on the mean free path for all inelastic electron scattering (lambdap), which is an important parameter for determining specimen thickness by using electron energy-loss spectroscopy, were investigated with crystalline Si and amorphous SiO2. First, thickness of Si film was measured with the convergent-beam electron diffraction method, while thickness of SiO2 particles was estimated from their spherical shape. Then from electron energy-loss spectra, lambdap was evaluated for Si film and SiO2 particles by changing the accelerating voltage (100 to approximately 300 kV) and the collection angle for the scattered electrons. Under the condition of no objective aperture, lambdap for Si film and SiO2 particles was found to increase with the increase of accelerating voltage and to take values of 180+/-6 nm (Si) and 247+/-8 nm (SiO2) at 300 kV. Also, it was found that lambdap in both cases decreases drastically with the increase of collection angle in the range smaller than 25 mrad, while it tends to take a constant value at the collection angle larger than 25 mrad at 200 kV.     

Determining surface orientations of transparent objects based on polarization degrees in visible and infrared wavelengths

Techniques for modeling an object through observation are very important in object recognition and virtual reality. A wide variety of techniques have been developed for modeling objects with opaque surfaces, whereas less attention has been paid to objects with transparent surfaces. A transparent surface has only surface reflection; it has little body reflection. We present a new method for obtaining surface orientations of transparent surfaces through analysis of the degree of polarization in surface reflection and emission in visible and far-infrared wavelengths, respectively. This parameter, the polarization degree of reflected light at the visible wavelengths, is used for determining the surface orientation at a surface point. The polarization degree at visible wavelengths provides two possible solutions, and the proposed method uses the polarization degree at far-infrared wavelengths to resolve this ambiguity.     

Numerical analysis of plasmon-resonance absorption in bisinusoidal metal gratings

We numerically investigate plasmon-resonance absorption of incident light energy by a bisinusoidal metal grating, i.e., one whose surface profile is sinusoidally corrugated in two orthogonal directions with a common period. Employing Yasuura's modal expansion method, we solve the problem of plane-wave diffraction by the grating and evaluate the absorption, which is observed as dips in diffraction efficiency curves. We examine the field distribution and energy flow in detail at the angles of incidence at which the absorption occurs. We show that the absorption is caused by coupling of the TM component of an evanescent order with surface plasmons. A phase-matching condition is used in the prediction of the incident angle at which the absorption occurs. This, together with the field profile in the presence of the resonance absorption, explains the mechanism of the absorption. We then illustrate interesting features of the absorption: enhancement of polarization conversion between the incident light and the reflected light and simultaneous excitation of two plasmon waves in directions that are symmetric with respect to the plane of incidence.     

Design Of Anti‐Slip Controller For An Electric Vehicle With An Adhesion Status Analyzer Based On The Ev Simulator

The In this paper, a simulator of a one‐wheel Electric Vehicle system is designed for testing an anti‐slip controller using the Motor‐Generator system. The drive motor of the M‐G system is used to simulate the drive wheel of the Electric Vehicle, and the load motor is used to simulate the load force of the chassis. In the driving process, the torque of the load motor is changed according to the drive force of the chassis that is calculated by the program. So it can simulate the dynamic process of the tire‐road system. Based on this simulator system, an anti‐slip controller based on an Adhesion Status Analyzer is proposed. Information about the wheel speed is acquired by using a Back EMF Observer. A load torque disturbance observer is designed to stabilize the acceleration of the wheels. The Adhesion Status Analyzer is used to generate safe acceleration commands for the anti‐slip controller. When a slip occurs, the anti‐slip controller will decrease the torque quickly, and at the same time, by estimating the dynamic status of adhesion, the Adhesion Status Analyzer will restrain the acceleration command within a safe area. The effectiveness of the proposed approach is verified by using the EV slip simulator.     

Acrobot control by learning the switching of multiple controllers

Reinforcement learning (RL) has been applied to constructing controllers for nonlinear systems in recent years. Since RL methods do not require an exact dynamics model of the controlled object, they have a higher flexibility and potential for adaptation to uncertain or nonstationary environments than methods based on traditional control theory. If the target system has a continuous state space whose dynamic characteristics are nonlinear, however, RL methods often suffer from unstable learning processes. For this reason, it is difficult to apply RL methods to control tasks in the real world. In order to overcome the disadvantage of RL methods, we propose an RL scheme combining multiple controllers, each of which is constructed based on traditional control theory. We then apply it to a swinging-up and stabilizing task of an acrobot with a limited torque, which is a typical but difficult task in the field of nonlinear control theory. Our simulation result showed that our method was able to realize stable learning and to achieve fairly good control.This work was presented, in part, at the 9th International Symposium on Artificial Life and Robotics, Oita, Japan, January 28–30, 2004     

Formate protects photosynthetic machinery from photoinhibition

In plants, environmental adversity often leads to the formation of reactive oxygen species (ROS) because of excess light energy. We found that incubation of rice leaves under high light intensity together with CO2-depleted air seriously damaged photosynthesis; however, the application of potassium formate (2 mM) before the photoinhibitory treatment protected the photosynthesis of the plant from photoinhibition. Further analysis revealed that formate protects PSII, RuBisCO, and FBPase from photoinhibition. Formate is thought to be involved in endogenous radical scavenging and/or in the supply of CO2, derived from the formate, thereby reducing oxidative damage to the photosystems under photoinhibitory conditions.     

Formate dehydrogenase in rice plant: growth stimulation effect of formate in rice plant

It was previously suggested that a population of phototrophic bacteria, Rhodopseudomonas palustris strain RN1 and Blastochloris sulfoviridis strain GN1 could be induced from granules in a lighted upflow anaerobic sludge blanket (LUASB) reactor. The present study showed that both strains RN1 and GN1 could use acetate, propionate, butyrate, and lactate as electron donors under anaerobic light conditions. The composition of organic acids in the effluent from the LUASB reactor was studied to investigate competitive consumption between acetogenic bacteria, methanogens, and phototrophic bacteria in the reactor. When acetate, propionate and lactate were supplied to the reactor, a small amount of acetate and propionate was observed in the effluent under light conditions. The concentrations of acetate and propionate increased under dark conditions compared with those under light conditions using organic acid and peptone media as the influent. When starch was supplied to the reactor, the concentrations of formate, acetate, propionate, butyrate, and lactate in the effluent were less than 0.5 mg C.l(-1) during operation under light and dark conditions. The concentrations of ammonium and phosphate in the effluent under dark conditions were higher than those under light conditions. These results suggested that phototrophic bacteria in the LUASB reactor consumed acetate and propionate as well as ammonium and phosphate in competition with methanogens and acetogenic bacteria.