Improved fuel use efficiency in microchannel direct methanol fuel cells using a hydrophilic macroporous layer

We demonstrate state-of-the-art room temperature operation of silicon microchannel-based micro-direct methanol fuel cells (μDMFC) having a very high fuel use efficiency of 75.4% operating at an output power density of 9.25 mW cm⁻² for an input fuel (3 M aqueous methanol solution) flow rate as low as 0.55 μL min⁻¹. In addition, an output power density of 12.7 mW cm⁻² has been observed for a fuel flow rate of 2.76 μL min⁻¹. These results were obtained via the insertion of novel hydrophilic macroporous layer between the standard hydrophobic carbon gas diffusion layer (GDL) and the anode catalyst layer of a μDMFC; the hydrophilic macroporous layer acts to improve mass transport, as a wicking layer for the fuel, enhancing fuel supply to the anode at low flow rates. The results were obtained with the fuel being supplied to the anode catalyst layer via a network of microscopic microchannels etched in a silicon wafer.     

A spatial evaluation of forest biomass usage using GIS

We conducted a spatial evaluation of forest biomass usage using a geographic information system (GIS) for the Japanese town of Yusuhara. In Japan, over 60% of the land is covered with forest, of which at least 40% is artificial forest. However, because of high labor costs, the profitability of forestry is decreasing, so timber cultivation is not done to the extent that it could be, and thinning has to be subsidized. Under these circumstances, much of the forest is deteriorating. Most of the thinning is accounted for by throwaway thinning, in which the resulting wood is not used. However, with the steep rise in oil prices and the intensification of global warming concerns, expectations are rising for the use of biomass energy from thinned timber that has previously been discarded. If thinned timber, logging residues, and offcuts are utilized for biomass energy and their economic value becomes apparent, profitability will improve for both final cutting and thinning. And in addition to forestry activities being invigorated, it will be possible for some of the deteriorating forests (which have associated dangers such as landslides) to recover. However, using thinned timber and logging residues is problematic in that profitability is affected by harvesting costs. Harvesting costs are largely determined by geographic factors and are higher for more distant stands. Accordingly, in this article, operational costs for different stands are calculated using GIS and matched with total demand in the subject region. In addition, stands with lower operational costs are identified and an investigation of a highly feasible use of forest biomass is carried out.     

A novel CO2 refrigeration system achieved by CO2 solid–gas two-phase fluid and its basic study on system performance

In this report, a new CO₂ refrigeration system is introduced, which can achieve a refrigeration capability below the CO₂ triple point of ?56.6 °C. The proposed CO₂ refrigeration system consists of two thermodynamic cycles arranged in cascade, where one is a CO₂ trans-critical cycle and another is a trans-triple-point cycle. An experimental set-up is constructed and tested in order to obtain a basic knowledge about this CO₂ system. Based on the measured data, it is concluded that the built CO₂ refrigeration system can operate continuously and stably, although dry ice particles exist in the closed CO₂ loops. An average COP (a ratio of cooling energy to the compressor power consumption) is measured at 2.45 in the present experiment range for the low-pressure system of the experimental set-up. In addition, the influence of the condensation temperature on the refrigeration cycle is investigated and more studies are needed for the future optimization work.     

Direct amination on 3-dimensional pyrolyzed carbon micropattern surface for DNA detection

Three-dimensional pyrolyzed carbon micropatterns were fabricated by using photolithography and pyrolysis process. Direct amination was achieved by functionalizing its surface with ultraviolet (UV) irradiation under ammonia gas. Quantified amino groups on the carbon surface were estimated by X-ray photoelectron spectroscopy. Hybridization intensity and intensity profile were investigated by epifluorescence microscopy.     

High‐pressure short time behavior of traction fluids

The squeeze film formation ability of traction fluids is studied under impact load by dropping a steel ball‐bearing against a flat anvil made of mild steel. The effect of the pressure–viscosity coefficient and of the viscosity is investigated for plastic impact. The depth difference between the lubricated surface dent and the dry dent increases linearly with the product αη of the pressure–viscosity coefficient α and the viscosity η. The importance of the lubricant parameter αη is observed under the squeeze film formation ability from contact voltage or elastohydrodynamic lubrication central film thickness measurement at rolling condition. The intensity of each impact collision is measured by means of an acoustic emission (AE) sensor. The high‐pressure short‐time solidification of traction fluids was confirmed by dent analysis after the impact tests and AE analysis under impact loads. Copyright © 2006 John Wiley & Sons, Ltd.     

Simulataneous analysis of reactivity of anilines in the hydrogen-isotope exchange reaction

In order to reveal the reactivity of a functional group in an aromatic compound having two substituents in the aromatic ring, the hydrogen-isotope exchange reaction （T-H exchange reaction） between tritiated water vapor （HTO vapor） and 4-amino-2-methylbenzenesulfonic acid （and 5-amino-2-methylphenol） were dynamically observed at 50℃ （and 70℃） in a gas-solid system. Consequently, the fact that the specific activity of the acid increased with time was obtained, and the T-for-H exchange reaction occurred. By applying the A＂-McKay plot method to the data observed, the rate constant of each functional group for the reaction was obtained. After the additive property of the Hammett＇s rule was applied to this work, the new substituent constants were obtained. From the above-mentioned, the following four items have been confirmed： （1） the reactivity of the functional groups can be dynamically analyzed, and the A＂-McKay plot method is useful to analyze the reactivity; （2） the additive property of the Hammett＇s rule is applicable to quantitative comparison of the reactivity of the functional groups; （3） the reactivity of the functional groups can be simultaneously analyzed by using the A ＂-McKay plot method in the T-H exchange reaction; and （4） the method used in this work is also useful for analyzing the reactivity of a certain material having some kinds of func- tional groups.     

Basic characteristics of Ar/N2 atmospheric pressure nonequilibrium microwave discharge plasma jets

To understand the mechanism of surface processing by atmospheric pressure nonequilibrium microwave discharge plasma jets of coaxial type without a resonator, we measured the vibrational and rotational temperatures in plasmas using optical emission spectroscopy. The plasma was excited by a microwave power supply, using a gas mixture of Ar and N₂ as the plasma gas, and changing the flow rate of N₂ gas. We also measured the change in the contact angle of a PET film before and after the plasma processing. It decreased as the plasma rotational temperature increased, indicating that the hydrophilicity of the PET surface was improved as the plasma rotational temperature became higher. © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Automated X‐ray inspection method for fillet‐less mounted chip components

Chip components mounted on the printed circuit board are rapidly being miniaturized. Furthermore, the fillet‐less chip soldering technique, which does not use a solder fillet, is widely used in portable products such as mobile phones. However, there is no method to inspect the soldering of fillet‐less chip mounting. In this paper, we propose an automated X‐ray inspection technique for fillet‐less chip mounting. It extracts three inspection parameters from the X‐ray image. In the experiments, we evaluate the repeatability and inspecting ability of the technique and confirm that sufficient information for failure detection is obtained. An automated X‐ray inspection system using this technique is now in operation at some factories, so in conclusion our automated method would be useful in practice. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

活性硅醇与ENR开环反应及对硫化胶力学性能的影响

以过氧羧酸为环氧化剂,制得环氧化天然橡胶(ENR)。通过从水玻璃中提取的活性硅醇与ENR的开环反应,得到含硅杂化材料ENR-SiO2,测试了其对NE硫化胶力学性能的影响,发现含硅杂化材料对NR硫化胶有明显的增强作用。     

Preparation of micron-scale monodisperse oil-in-water microspheres by microchannel emulsification

Micron-scale monodisperse oil-in-water (O/W) micropheres (MS) were prepared using a novel microchannel (MC) emulsification technique. The characteristics of the MS preparation and the O/W-MS prepared were studied. Soybean oil and medium-chain triacyglycerol (MCT) were used as the disprrsed phase, and physiological saline was used as the continuous phase. Silicon MC with 1 to 3μm-equivalent channel diameters were employed. A novel MC module was devised to easily recover the O/W-MS prepared. The effects of the channel shape on the behavior of MS formation, on the MS size, and on the distribution were investigated. An MC with a terrace at the MC outlet stably yielded micron-scale monodisperse O/W-MS; the MS had diameters of about 5 μm, and their coefficients of variation were below 9%. Monodisperse food-grade O/W-MS with diameters of about 4 μm could be obtained by using polyglycerol fatty acid ester as the surfactant. The size and size distribution of the recovered O/W-MS remained almost constant over 60 d, demonstrating their long-term stability.