Indoor and outdoor concentrations of Japanese cedar pollens and total suspended particulates: A case study at a kindergarten in Japan

Japanese cedar pollinosis (JCP) caused by allergenic cedar and cypress pollens is one of major economic and health issues in Japan. The present study reported here aimed to provide basic data to understand the status of early life exposures to airborne cedar and cypress pollens in school settings. In particular, the study investigated relationships between indoor and outdoor concentrations of airborne cedar and cypress pollens and total suspended particulates (TSP) in a kindergarten in Japan. Overall, outdoor concentrations of the airborne pollens and TSP were higher than the indoor concentrations, i.e., indoor to outdoor (I/O) ratios of 0.043–0.055 and 0.545 for the airborne pollens and TSP, respectively. The smaller I/O ratios for the pollens were expected because the larger pollen grains (20–30 μm in diameter) were less likely penetrated to indoor environment than for smaller airborne particulates. The present study also found increased TSP concentrations during the pollen season was likely attributed to increased airborne pollen concentrations. By understanding the status of indoor and outdoor concentrations of airborne cedar and cypress pollens in school settings, early life exposures to these allergenic pollens should be effectively minimized to prevent subsequent progression to JCP symptoms.     

Estimation of regional stress by FEM for a heterogeneous rock mass with a large fault

Defining regional stress for a heterogeneous rock mass composed of different rock bodies and a large fault as a displacement boundary condition that is consistent with the mean trend of the in situ stress, we propose a method for determining regional stress from limited stress data by using a 3D finite element method (FEM). First, this method was applied to a small-scale heterogeneous model with a large planar fault that penetrates the region, to clarify the estimation accuracy and the effects of poor modeling and incomplete stress data. The results showed that (1) the method proposed in this study can accurately estimate the stress distribution in the region under consideration except at the bottom when the sliding area of the fault is small, (2) the reproducibility of the given stress can be used to estimate appropriate values of the normal and shear stiffnesses of the fault when the fault is homogeneous, and (3) both incomplete stress data and the assumption that the fault does not slide decrease the accuracy of stress estimation while the given stresses are approximately reproduced. Next, the method was applied to the Tono area, Japan, where a large fault with a complex geometry, called the Tsukiyoshi fault, exists. The results obtained under the assumption that the Tsukiyoshi fault does not slide showed that (1) the stress distribution was estimated reasonably well only for a narrow region that contained the boreholes at which the stress used in the inverse analysis was measured, (2) the stress in the area shows a large scatter and a non-linear trend with depth, which is mainly caused by the Tsukiyoshi fault, and (3) when a fault is heterogeneous, comprehensive examination for the states of the stress and displacements on the fault is needed to obtain a reasonable estimation for the regional stress.     

Thermotropic and Barotropic Phase Behavior of Phosphatidylcholine Bilayers

Bilayers formed by phospholipids are frequently used as model biological membranes in various life science studies. A characteristic feature of phospholipid bilayers is to undergo a structural change called a phase transition in response to environmental changes of their surroundings. In this review, we focus our attention on phase transitions of some major phospholipids contained in biological membranes, phosphatidylcholines (PCs), depending on temperature and pressure. Bilayers of dipalmitoylphosphatidylcholine (DPPC), which is the most representative lipid in model membrane studies, will first be explained. Then, the bilayer phase behavior of various kinds of PCs with different molecular structures is revealed from the temperature–pressure phase diagrams, and the difference in phase stability among these PC bilayers is discussed in connection with the molecular structure of the PC molecules. Furthermore, the solvent effect on the phase behavior is also described briefly.     

Recycling of aluminum matrix composites

Separation of matrix metals in composites was tried on alumina short fiber-reinforced aluminum and 6061 alloy composites and SiC whisker-reinforced 6061 alloy composite for recycling. It is possible to separate molten matrix metals from fibers in the composites using fluxes that are used for melt treatment to remove inclusions. About 50 vol pct of the matrix metals was separated from the alumina short fiber-reinforced composites. The separation ratio of the matrix from the SiC whisker-reinforced 6061 alloy composite was low and about 20 vol pct. The separation mechanism was discussed thermodynamically using interface free energies. Since the flux/fiber interface energy is smaller than the aluminum/fiber interface energy, the replacement of aluminum with fluxes in composites takes place easily. Gases released by the decomposition of fluxes act an important role in pushing out the molten matrix metal from the composite. The role was confirmed by the great amount cavity formed in the composite after the matrix metal flowed out.     

Electron paramagnetic resonance spectra of Pr ions doped in BaMO3 (M=Ce, Zr, Sn) and SrCeO3

The isotropic electron paramagnetic resonance (EPR) spectra of powders with Pr⁴⁺ doped in BaMO₃ (M=Ce, Zr, Sn) were measured at 4.2 K. A very large hyperfine interaction with the ¹⁴¹Pr nucleus was observed. The results were analyzed based on the weak field approximation, and the g values and hyperfine coupling constants A were obtained. The measured g values are much smaller than |−10/7|, showing that the crystal field effect on the behavior of a 4f electron is large. The value of |g| decreases from 0.741 (Pr⁴⁺–BaCeO₃) to 0.583 (Pr⁴⁺–BaSnO₃), which is caused by the increase of the crystal field due to the shrinking of the lattice. In contrast, the hyperfine coupling constants are almost constant: A=0.060(1) cm⁻¹. The anisotropic EPR spectra were measured for the case of Pr⁴⁺–SrCeO₃, which indicates that the octahedral array of oxygen ions about Pr⁴⁺ is considerably distorted for this system.     

220,000‐r/min, 2‐kW PM motor drive for turbocharger

This paper describes an ultrahigh‐speed permanent‐magnet synchronous motor drive, which is embedded in a turbocharger of an internal‐combustion engine. The electrical drive makes it possible to enhance output power of the turbocharger in a motoring mode and to retrieve combustion energy from exhaust gas in a regenerating mode. Computer simulations and experimental tests are conducted to examine various operation characteristics of a prototype. The experimental data demonstrate 220,000‐r/min operation at 2.2‐kW inverter output power, in good agreement with the simulation results and proving the feasibility of the proposed system. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 161(3): 31–40, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20408     

A METHOD FOR THE PREPARATION OF RAW POWDER FOR THE TANTALUM CAPACITOR: INFLUENCE OF PARTICLE SIZE AND BINDER CONTENT

Raw powder for use in the tantalum solid electrolytic capacitor was prepared by different processes, that is, the wet method (currently used conversion method) and the dry method (the proposed method). The properties of prepared powder from the dry method were compared with those of the wet method. The present report has focused on the relationship between the conditions of binder preparation and the properties of the prepared powder, such as the particle size distribution, angle of repose, and the tap density, respectively. Furthermore, the utility of the dry method was investigated.

Based on the results, it has been clarified that the properties of powder prepared by the dry method differ from those of the wet method. In the case of the dry method, it is suggested that the mechanism of preparation of the fine binder (PMMA powder) differs from that of the coarse binder. Furthermore, based on the experimental results, it has been suggested that the dry method could be used as the preparation method of the raw powder used in the tantalum solid electrolytic capacitor.     

Microprocessor-Based Decoupled Control of Manipulator Using Modified Model-Following Method with Sliding Mode

A methodology of discontinuous feedback and continuous feedforward control is developed to achieve accurate decoupled tracking in a class of nonlinear, time varying systems in the presence of disturbances, parameter variations and nonlinear dynamic interactions. The method is based on an improved variable structure control with a sliding mode.