Development of passive heat control system for direct methanol fuel cell using electric double layer capacitor

A direct methanol fuel cell (DMFC) is highly anticipated as a new, high‐density energy source for mobile usage; however, its poor power density presents a problem. As a result, the size of portable electronic equipment using DMFCs is far larger than that of equipment using another type of battery. In addition, steady power supply control is difficult, because the output power of the DMFC is affected by the environment. First, this paper presents a pulse charge control system that is a new control system applied to a mobile device, which uses the DMFC and an electric double layer capacitor (EDLC), then describes the new passive heat control and presents experimental results. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 179(1): 46–53, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21129     

Development of a maximum‐power‐point‐limiting control system for a direct methanol fuel cell

A new maximum‐power‐point limiting (MPPL) control method for a direct methanol fuel cell (DMFC) was proposed. In regard to achieving MPPL, it was affirmed by experiment that it is possible to control the DMFC by simply ensuring that its voltage does not fall below a certain level regardless of its state. An MPPL control system that accomplishes the DMFC voltage limitation required for MPPL control by using a ‘soft‐start function’ fitted in a ready‐made DC/DC converter was developed. It was confirmed by experimental tests that the circuit board of the developed MPPL control system can perform DMFC voltage limitation control. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

PCR-RFLP identification of prohibited animal derived DNA in animal feed

A method for confirming identification of prohibited species tissue in animal feed has been developed on the basis of PCR-RFLP analysis. In Japan, to prevent the spread of BSE through animal feed, the use of animal protein in feed has been regulated. Species-specific PCR detection of prohibited species materials in feed has been used as one of a series of laboratory tests to ensure the proper implementation of the feed regulations. However, since the result of this PCR method is determined only by amplicon length, it is sometimes necessary to confirm whether or not the positive result is due to the effect of a non-specific reaction. For this purpose, DNA sequencing is the best way to confirm the test result but it is not suitable for routine analysis because of the required time and cost. In this study, we developed an easy and rapid method to confirm the species identification (mammals, ruminants and cattle) by using 4 restriction enzymes: SmlI, MboI, BlnI and Hpy188III. This PCR-RFLP method, which ensures identification of prohibited animal species in feed, is useful for enhancing the reliability of feed inspection for BSE prevention. This method will be added to the Official Methods of Feed Analysis.     

Heat transfer enhancement in duct with blunt body inserted close to its wall

This paper shows the effects of clearance length between a body and a duct wall, and duct height on the heat transfer characteristics and flow behavior at a downstream region of the body when a blunt body was set in a parallel plate duct with some distance separating it from the duct wall as a turbulence promoter. For the ratio of clearance to body height, C/D = 0.05–01, the heat transfer was characterized by the reattachment of shear flow separated from the body. Furthermore, the heat transfer depended on both the reattachment flow and the separation vortex at C/D = 0.15–0.2, and the side vortex induced by Karman vortex at C/D = 0.25–0.275 was also observed. We found the reattachment flow gives a superior effect to enhance heat transfer at a low Reynolds number, but at a larger Reynolds number, the side vortex induced by Karman vortex becomes more effective to heat transfer enhancement. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(5): 336–349, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20067     

Surface-Chemical Criteria for Optimum Adhesion

According to Bikerman, who attributes failure in adhints to a weak boundary layer, it is almost impossible and meaningless to correlate adhesive strength to surface-chemical properties of adhints. Though his assertion seems to be confirmed by the recent studies of Schonhorn and his coworkers on the methods of CASING and TCR, not a few results have yet been accumulated, which show a close relation between them. In this paper surface-chemical criteria for the optimum adhesion are investigated and the minimum interfacial tension or the maximum wetting pressure is deduced from the published data and our own as a first approximation. It is emphasized that, when critical surface tension γ_c would be used as a measure of surface-chemical properties of solid, its variability according to liquid series (nonpolar, polar and hydrogen bonding liquids) should be carefully taken into consideration. The importance is shown for polyethylene and its fluorine substituted polymers, using newly measured contact angle data and Zisman's data. Results of Levine et al. and Schonhorn et al. on adhesive shear strength with epoxy adhesives are replotted against available values of γ_c obtained by the use of hydrogen bonding liquid (γ_c^c), which are thought to reflect wetting behaviors of epoxy adhesives quite well. Each curve shows a maximum around γ_c^c = 40 dyne/cm with few points falling off the curves.     

Enhancement of oxygen reduction activity with addition of carbon support for non-precious metal nitrogen doped carbon catalyst

An improved synthesis scheme of non-precious metal N-doped carbon catalysts for oxygen reduction reaction is reported. The non-precious metal N-doped carbon catalysts were prepared by pyrolysis of the mixture (phenol resin, Ketjen black carbon support and cobalt phenanthroline complex). The drastic improvement of distribution state of Ketjen black supported non-precious metal N-doped carbon catalysts was observed by means of transmission electron microscopy (TEM). In addition, the non-precious metal N-doped carbon catalyst synthesized with Ketjen black carbon support showed much higher oxygen reduction reaction (ORR) activity relative to unsupported non-precious metal N-doped carbon catalyst in O₂-saturated 0.5 mol l⁻¹ H₂SO₄ at 35 °C. Moreover, the highest ORR activity was obtained with addition of optimum amount of Ketjen black carbon support was thirtyfold compared to unsupported non-precious metal N-doped carbon catalyst at 0.7 V. Similarly, the performance of a polymer electrolyte fuel cell (PEFC) using the non-precious metal N-doped carbon catalyst as the cathode electrode catalyst was obviously better than that of the non-precious metal N-doped carbon catalyst before optimization. Microstructure, specific surface area and surface composition of the non-precious metal N-doped carbon catalysts were analyzed by XRD, XPS and BET measurement with nitrogen physisorption, respectively.     

Variation of Fructooligosaccharides and their Metabolizing Enzymes in Onion Bulb (Allium cepa L. cv. Tenshin) During Long-term Storage

ABSTRACT: The objective of this study was to assess the status of fructooligosaccharides (FOS) in onion bulbs ( Allium cepa L. cv. Tenshin) and their metabolizing-enzymes—1-fructoexohydrolase (1-FEH), 1-kestose hydrolyzing enzyme (1-KH), fructan:fructan 1^F-fructosyltransferase (1-FFT) and fructan:fructan 6^G-fructosyltransferase (6G-FFT)—during storage at 15°C. Fructose varies slightly, whereas 1-kestose peaked after 6 wk and then decreased progressively during the last 18 wk of storage. Lower degree of polymerization (DP) 3 to 6) FOS, higher (DP 7 to 12) FOS, total FOS, and total carbohydrates showed similar and close patterns during 24 wk. They varied slightly at the beginning of the storage period; afterward they decreased progressively and regularly during the last 20 wk of storage. 1-FEH and 1-KH activities were low but peaked abruptly after 12 and 16 wk, respectively, after which they decreased to levels higher (1-FEH) or similar (1-KH) to those observed at the beginning of the storage. Surprisingly, 1-FFT activity showed similar pattern to the variation of 1-KH hydrolyzing activity; on the other hand, 6G-FFT, although higher, was stable during 16 wk but decreased after that. The results allowed us to associate FOS to the dormancy and sprouting states, and the peaks of the degrading enzymes were shown to signal the release of dormancy of onion bulb.     

Teleost fish scales: a unique biological model for the fabrication of materials for corneal stroma regeneration

The corneal stroma is composed of multiple lamellae, each containing closely packed collagen fibrils. The orientation of fibrils in a lamella is parallel, but those in different lamellae are orthogonal. As a result, the corneal stroma has a characteristic orthogonal plywood-like structure. Such a highly-regulated three-dimensional arrangement of collagen fibrils gives strength and transparency to the corneal stroma, but it also presents a challenge in the fabrication of materials to replace it. A bioinspired technology is required to process such materials, but the regulatory mechanism of collagen-fibril orientation is still unknown. The low regenerating activity of the corneal stroma seems to be a major factor preventing progress in this field of research. A similarly highly-ordered arrangement of collagen fibrils can be seen in the basal plates of teleost fish scales. Moreover, the scales have high regenerating ability. When a scale is mechanically lost, a new scale is rapidly regenerated. The cells that produce the basal plates are extremely activated; thus, production of the highly-ordered collagen fibrils is very rapid. Therefore, the regenerating scales should be a uniquely helpful biological model for studying the regulatory mechanism of collagen-fibril orientation. Fish-scale collagen has another advantage for use as a biomaterial: the low probability of zoonotic infection. Therefore, scale collagen is a most promising biomaterial for fabricating three-dimensionally arranged collagen fibers to substitute for the corneal stroma. Three tasks that must be clarified for the bioinspired production of a corneal substitute from fish scale collagen are proposed.