Performance of a solid oxide fuel cell couple operated via in situ catalytic partial oxidation of n-butane

The operation of a pair of anode-to-anode-facing solid oxide fuel cells (SOFCs) via in situ catalytic partial oxidation (CPO) of n-butane was investigated. In this simple “no-chamber” setup, butane is partially oxidized by heterogeneous reactions inside the porous anodes, providing processed fuel and the heat required for SOFC operation. The cell couple yielded a power density of up to 270 mW cm⁻², and the maximum total power obtained was 1.2 W with cell sizes of 13 mm × 23 mm. The maximum electrical efficiency was 1.3%. High CO concentrations of up to 1000 ppm were detected in the exhaust gas, indicating that the cell couple could not efficiently consume the complete provided fuel. A flame, lit at the exhaust, minimized the carbon monoxide level while having insignificant influence on the cell performance. Thermal insulation of the cell couple improved the output remarkably, showing the strong influence of temperature on cell performance. The two cells had a distance of only 2 mm, suggesting a potential for high volumetric power densities in multi-cell configurations for a self-sustained combined heat and power system.     

Thermoelectric properties of β-FeSi2 with B4C and BN dispersion by mechanical alloying

The B₄C- and BN-dispersed -FeSi₂ thermoelectric materials were synthesized by mechanical alloying and subsequent hot pressing. The effects of the B₄C and BN dispersion on the thermoelectric properties, such as Seebeck coefficient, electrical resistivity and thermal conductivity etc., of the -FeSi₂ were investigated. For the sample with B₄C and BN addition, a larger amount of the residual phase was detected in the X-ray diffraction patterns than the sample without addition. In the case of the BN addition, the Seebeck coefficient was enhanced by BN addition above 700 K, and the electrical resistivity also increased with increasing amount of BN. This is considered to result from doping of a small amount of B into the phase due to partial decomposition of the BN phase. The fine dispersion of BN particles in the phase matrix was quite effective for reducing the thermal conductivity as compared to the B₄C addition over the entire temperature range. The figure of merit, Z, of the -FeSi₂ was significantly enhanced by BN addition.     

A method for calculating the electromagnetic noise of a motor-driven thin blade fan

An urgent need exists to develop a method of predicting the noise level of a blade fan attached to a motor shaft. To satisfy this requirement, we developed a method for calculating the sound generated when a rotating blade is excited by the torque pulsation of a motor. The sound pressure values calculated by the new method for a rotating blade were found to correspond well with experimentally measured ones.     

Minimal design for human–agent communication

Robots have been envisaged as both workers and partners of humans from the earliest period in their history. Therefore, robots should become artificial entities that can socially interact with human beings in social communities. Recent advances in technology have added various functions to robots. The development of actuators and grippers show us infinite possibilities for factory automation, and robots can now walk and perform very smoothly. All of these functions have been developed as solutions for improving robot movement and performance. However, there are many remaining problems in the communication between robots and humans. Communication robots provide one approach to the realization of embodied interfaces. Furthermore, the unsolved problems of human–robot communication can be clarified by adopting the concept of subtractive methods. In this article, we consider the minimal design of robots from the viewpoint of designing communication. By minimal design, we mean eliminating the nonessential portions and keeping only the most fundamental functions. We expect that the simple and clean nature of minimally designed objects will allow humans to interact with these robots without becoming uninterested too quickly. By exploiting the fact that humans have “a natural dislike for the absence of reasoning,” artificial entities built according to minimal design principles can extract the human drive to relate with others. We propose a method of designing a robot that has “character” and is situated in a social context from the viewpoint of minimal design. This work was presented in part at the 10th International Symposium on Artificial Life and Robotics, Oita, Japan, February 4–6, 2005     

Role of Stripes in Spin and Charge Dynamics of Underdoped La2−x Sr x CuO4

We investigate the electronic states of underdoped La _2–x Sr _x CuO ₄ (LSCO) by using a microscopic model, i.e., t-t-t-J model, containing charge stripes. The numerically exact diagonalization calculation is employed on small clusters. The physical properties observed in the angle-resolved photoemission and optical conductivity experiments are consistently explained in the model with vertical stripes, but not diagonal ones. These results demonstrate a crucial role of the vertical stripes in underdoped LSCO.     

Effect of anti-IL-4 and anti-IL-5 antibodies on allergic airway hyperresponsiveness in mice

In order to study the role of IL-4 and IL-5 in allergen-induced airway hyperresponsiveness in mice, the effect of the combined administration of anti-IL-4 and anti-IL-5 monoclonal antibodies (mAbs) on IgE response, airway inflammation and airway hyperresponsiveness was studied in sensitized Balb/c mice. Three inhalations of antigen caused an increase in the number of eosinophils in bronchoalveolar lavage fluid and in airway responsiveness to acetylcholine, with a significant elevation in the serum antigen-specific IgE level. Anti-IL-4 mAb inhibited IgE production but did not affect airway eosinophilia or hyperresponsiveness. Moreover, anti-IL-5 mAb inhibited airway eosinophilia but did not affect IgE production or airway hyperresponsiveness. The combined administration of anti-IL4 and anti-IL-5 mAbs, however, inhibited IgE antibody production, airway eosinophilia and hyperresponsiveness. These results suggest that inhibitory action of IL-4 and IL-5 in combination can effectively suppress the onset of antigen-induced airway hyperresponsiveness in mice.     

Endothelin converting enzyme inhibitor protects development of right ventricular overload and medial thickening of pulmonary arteries in rats with monocrotaline-induced pulmonary hypertension

We evaluated the effects of FR901533, endothelin converting enzyme inhibitor, on development of right ventricular overload and medial thickening of pulmonary arteries in rats with monocrotaline-induced pulmonary hypertension. Pulmonary hypertension was induced by a single injection of monocrotaline (80 mg/kg). Twenty-four hours later (day 1), continuous subcutaneous injection of FR901533 (100 mg/kg/day) was started. Right ventricular systolic pressure, mass ratio of right ventricle to left ventricle, right ventricular wall thickness, right ventricular myocardial fiber diameter, percent medial thickness, and percent smooth muscle area in pulmonary arteries were significantly less in rats that received FR901533 than in the control with monocrotaline on day 28. Both immunoreactivities of endothelin-1 in pulmonary arteries and plasma endothelin-1 levels were observed significantly less in rats treated with FR901533 than in the control with monocrotaline. There were significant increased immunoreactivities of endothelin-B receptor in pulmonary arteries in rats that received FR901533 as compared with those in the control with monocrotaline. FR901533 (100 mg/kg/day), protected the development of right ventricular overload and medial thickening of pulmonary arteries in a rat model of pulmonary hypertension.     

Smoke extract stimulates lung epithelial cells to release neutrophil and monocyte chemotactic activity

Inflammatory cells accumulate within the lungs of cigarette smokers. Current concepts suggest that these cells can induce protease-antiprotease and/or oxidant-antioxidant imbalance(s), which may damage the normal lung alveolar and interstitial structures. Because type II pneumocytes line the alveolar space, and because the inflammatory cells migrate and reside at the alveolus, we postulated that the type II pneumocytes might release chemotactic activity for neutrophils and monocytes in response to smoke extract. To test this hypothesis, A549 cells were cultured and the supernatant fluids were evaluated for the neutrophil and monocyte chemotactic activity (NCA and MCA) by a blind-well chamber technique. A549 cells released NCA and MCA in response to smoke extract in a dose- and time-dependent manner (P < 0.05). Checkerboard analysis showed that the activity was chemotactic. Partial characterization of NCA and MCA revealed that the activity was partly heat labile, trypsin sensitive, and ethyl acetate extractable. Lipoxygenase inhibitors and cycloheximide inhibited the release of NCA and MCA. Molecular sieve column chromatography showed multiple peaks for both NCA and MCA. NCA was inhibited by anti-human-interleukin (IL)-8 antibody, granulocyte colony-stimulating factor (G-CSF) antibody, or leukotriene (LT)B4 receptor antagonist. Monocyte chemoattractant protein (MCP)-1 antibody or LTB4 receptor antagonist inhibited MCA. Immunoreactive IL-8, G-CSF, MCP-1, and LTB4 significantly increased in the supernatant fluids in response to smoke extract. These data suggest that the type II pneumocytes may release NCA and MCA and modulate the inflammatory cell recruitment into the lung.