Segregation behaviors and radial distribution of dopant atoms in silicon nanowires

Gaining an understanding the dynamic behaviors of dopant atoms in silicon nanowires (SiNWs) is the key to achieving low-power and high-speed transistor devices using SiNWs. The segregation behavior of boron (B) and phosphorus (P) atoms in B- and P-doped SiNWs during thermal oxidation was closely observed using B local vibrational peaks and Fano broadening in optical phonon peaks of B-doped SiNWs by micro-Raman scattering. Electron spin resonance (ESR) signals from conduction electrons were used for P-doped SiNWs. Our results showed that B atoms preferentially segregate in the surface oxide layer, whereas P atoms tend to accumulate in the Si region around the interface of SiNWs. The radial distribution of P atoms in SiNWs was also investigated to prove the difference segregation behaviors between of P and B atoms.     

Graphene and nanostructured MnO2 composite electrodes for supercapacitors

Graphene-based materials are promising electrodes for supercapacitors, owing to their unique two-dimensional structure, high surface area, remarkable chemical stability, and electrical conductivity. In this paper, graphene is explored as a platform for energy storage devices by decorating graphenes with flower-like MnO₂ nanostructures fabricated by electrodeposition. The as-prepared graphene and MnO₂, which were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), have been assembled into an asymmetric supercapacitor. The specific capacitance of the graphene electrode reached 245 F/g at a charging current of 1 mA after an electro-activation process. This value is more than 60% larger than the one before electro-activation. The MnO₂ nano-flowers which consisted of tiny rods with a thickness of less than 10 nm were coated onto the graphene electrodes by electrodeposition. The specific capacitance after the MnO₂ deposition is 328 F/g at the charging current of 1 mA with an energy density of 11.4 Wh/kg and 25.8 kW/kg of power density. This work suggests that our graphene-based electrodes are a promising candidate for the high-performance energy storage devices.     

NOVEL WATER FACILITIES FOR CREATION OF COMFORTABLE URBAN MICROMETEOROLOGY

The cooling effects of artificial water facilities – fountains, waterfalls and urban canals – have not received much attention. To improve the meso-space thermal environment in an urban area, especially that during the midsummer, we propose using novel artificial water facilities to alter the temperature and humidity, so as to improve pedestrian comfort. To study this, we have carried out field measurements and wind tunnel tests, and we report the results in this paper. At first we made measurements of wind velocity, temperature and humidity around such artificial water facilities in Tennoji Park in Osaka city (a typical Japanese large city). The results showed reduced temperatures on the leeward side, and demonstrated the usefulness of water facilities in improving the thermal environment. Also, we constructed an insulated 1/400 scale wind tunnel model of the situation and measured, by means of X-type hot wire anemometer, the air currents on the wind tunnel surfaces in urban, suburban and rural terrains. We also measured, using fine-gauge T-type thermocouples, the air temperature distribution in front of and behind the model of the water facility. The results confirmed the qualitative ranges of the cooling effect provided by the actual water facilities. In particular, the cooling effect produced by a 1.0 mm diameter nozzle fountain was found to extend a distance downstream equal to ten times the height of spout.     

Conductive polymer patterned media fabricated by diblock copolymer lithography for scanning multiprobe data storage

A conductive polymer dot pattern has been fabricated as a patterned medium using diblock copolymer lithography (DCL) for scanning multiprobe data storage systems (SMDSSs). DCL can easily provide a higher dots pattern density than that obtained using electron beam lithography. For DCL, the microphase-separated structure of polystyrene-block-polymethylmethacrylate is utilized. Then, the closed dot pattern of polyaniline (PANI) with a center to center distance of adjacent dots of 30?nm is fabricated by DCL. Electrical modification experiments of the fabricated PANI dots are demonstrated using scanning probe microscopy (SPM). As a result, the conductivities of the modified dots are selectively changed by applying modification voltages with the tip of the SPM probe. Recording on the conductive polymer with 30?nm pitch at the minimum can be demonstrated, which corresponds to a recording density of ～700?Gbits?inch(-2). These results show that the conductive polymer patterned medium has the potential ability to achieve high-density recording for SMDSSs.     

Effects of human hair and nail proteins and their films on rat mast cells

Human hair and nail are valuable materials for producing individual corresponding biocompatible materials. A rapid and convenient protein extraction method (Shindai method) and novel procedures for preparing their protein films from their extracts have been developed using human hair and nail. The effects of the human hair and nail proteins and their films on histamine release from rat peritoneal mast cells were investigated. Both protein solutions and their films, mainly consisting of keratins and matrix proteins, did not induce histamine release from the mast cells. Scanning electron microscopy (SEM) also showed that the mast cells were only slightly affected by adding the human hair and nail proteins or by incubating on their protein films. The IgE-dependent histamine release was inhibited by the hair and nail proteins and their films. Incubation of the mast cells with the hair and nail proteins prior to the addition of the IgE serum resulted in a high inhibition (50%) of the histamine release, while the inhibition was approximately 10% when the protein solutions were mixed with the mast cells after incubation with the IgE serum. These results suggest that the human hair and nail proteins and their films will be useful materials for antiallergic actions.     

Dust Explosion Characteristics of Aluminum, Titanium, Zinc, and Iron-Based Alloy Powders Used in Cold Spray Processing

Compared to conventional thermal spray coating, cold spray processing typically employs finer, smaller-diameter metal powders. Furthermore, cold-sprayed particles exhibit fewer surface oxides than thermally sprayed particles due to the absence of particle melting during spraying. For these reasons, it is important to consider the potential for dust explosions or fires during cold spray processing, for both industrial and R&D applications. This work examined the dust explosion characteristics of metal powders typically used in cold spray coating, for the purpose of preventing dust explosions and fires and thus protecting the health and safety of workers and guarding against property damage. In order to safely make use of the new cold spray technology in industrial settings, it is necessary to manage the risks based on an appropriate assessment of the hazards. However, there have been few research reports focused on such risk management. Therefore, in this study, the dust explosion characteristics of aluminum, titanium, zinc, carbonyl iron, and eutectoid steel containing chromium at 4 wt.% (4 wt.% Cr-eutectoid steel) powders were evaluated according to the standard protocols JIS Z 8818, IEC61241-2-3(1994-09) section 3, and JIS Z 8817. This paper reports our results concerning the dust explosion properties of the above-mentioned metal powders.     

Water Cut-Off Performance of H-Jointed Steel Pipe Sheet Piles with H-H Joints Attaching Water-Swelling Materials

In this research, under various conditions, we evaluate the water cut-off performance of H-jointed steel pipe sheet piles (SPSPs) with the H-H joints attaching water-swelling materials which are components of SPSPs for water cut-off in a coastal waste landfill site. Specifically, we research the water cut-off performance when these H-H joints have foreign particles, when they are in a wet-dry cyclic condition, and when the water-swelling material has deteriorated. As a result of this research, it has been found that in any of the above cases, H-jointed SPSPs with H-H joints attaching water-swelling materials are capable of providing water cut-off performance, and meet seepage control work standards as long as they are under less than certain pressure levels to be considered in coastal waste landfill sites. Also, it has been proved that the above conditions do not affect the water cut-off performance of H-jointed SPSPs with H-H joints attaching water-swelling materials.     

Mega‐solar optimal allocation using data envelopment analysis

In this paper, the optimal allocation of mega‐solar is examined using data envelopment analysis (DEA). A great deal of attention is paid to photovoltaic power generation in Japan. Because such power generation can be freely used, it is attractive in Japan, which has few natural resources. The allocation of mega‐solar, a large‐scale photovoltaic power generation method, is an important problem for meeting the hope of e?cient operation. We tried to apply DEA in Shizuoka Prefecture and to solve this issue. In this type of DEA application, some analyses often result in zero weighting factors in the parameters of some items to be studied, which implies that the corresponding items are not appropriately evaluated. The existing studies do not give special consideration to this situation. In this study, a new calculation scheme is proposed, the above‐stated problems are successfully resolved, and the optimal candidate sites have been selected for the mega‐solar allocation. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(4): 24–32, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22322     

Expression of Aspergillus oryzae phytase gene in Aspergillus oryzae RIB40 niaD(-)

Aspergillus oryzae RIB40 niaD(-) was transformed using a plasmid constructed with the A. oryzae phytase gene and pNAN8142 vector. The culture broth of the transformant, which was grown in a medium containing starch as a carbon source and polyvinylpyrrolidone showed phytase activity of a maximum of 2.0 units ml(-1) at 37 degrees C, pH 5.5.