Development of high water-content cutting fluids with a new concept: Fire prevention and environmental protection

Using water-insoluble cutting fluids, which are good in lubricity but easy to mist, always risks firing and environmental problems. On the other hand, the current water-soluble coolants fail to deliver sufficient lubricity to heavy cutting applications. This study has newly proposed and developed a high water-content cutting fluid, based upon a new concept of having high lubricity despite of its water-soluble nature. As compared to the commercialized water-insoluble cutting fluid, the new cutting fluids shows a better capability of preventing oil mist and is fully applicable into cutting of various metallic materials, particularly effective in cutting of S45C and SUS304. The study also reveals a fact that a sulfur-type extreme pressure agent is the key element to enhance the cutting performance at high temperature.     

Investigation of self-assembled monolayer treatment on SiO2 gate insulator of poly(3-hexylthiophene) thin-film transistors

We have investigated self-assembled monolayer (SAM) treatment on SiO₂ gate insulator of poly(3-hexylthiophene) (P3HT) thin-film transistor (TFT), and demonstrated a correlation between mobility and surface free energy of the insulator. The device with lower surface free energy shows higher mobility. The docosyltrichlorosilane (DCTS)-treated device exhibits the best performance among the various SAM-treated devices examined. Field-effect mobility, on/off ratio and threshold voltage of the DCTS-treated P3HT TFT were 0.015 cm²/Vs, >10⁵ and −14 V, respectively.     

Effect of magnetron sputtering conditions and subsequent annealing on the structure and magnetic properties of Fe97−x Zr3N x films

X-ray diffraction analysis was used to study the structure of Fe_97?x Zr₃N _x thin films produced under different conditions of rf magnetron sputtering (on rotary and stationary substrates) and subsequent annealing. Either a single-phase structure, namely, a supersaturated bcc α-(FeN) solid solution, or a mixed structure that consists of two crystalline phases, such as a supersaturated bcc α-Fe(N) solid solution and an fcc Fe₄N nitride, and a Fe-based amorphous phase were shown to be formed in films deposited on either stationary or rotating substrate, respectively. As the annealing temperature increases, the content of nitrogen in the bcc phase decreases; the grain size of the bcc phase in the films deposited on rotating and stationary substrates increases from 8 to 14 nm and from 10 to 30 nm, respectively; the amount of the Fe₄N phase increases. The results of the study of the magnetic properties of the films are reported. The maximum saturation induction B _s reached is 1.8–1.9 T; the minimum coercive force H _c is 1 Oe. The optimum combination of the magnetic properties (B _s = 1.8–1.9 T and H _c = 1.5–1.8 Oe) is observed for the films deposited on the rotating substrate and subsequently annealed at 400°C.     

Effect of film thickness on ferroelectric domain structure and properties of Pb(Zr0.35Ti0.65)O3/SrRuO3/SrTiO3 heterostructures

Epitaxial Pb(Zr_0.35Ti_0.65)O₃ (PZT) thin films with tetragonal symmetry and thicknesses ranging from 45 to 230 nm were grown at 540 °C on SrRuO₃-coated (001)SrTiO₃ substrates by pulse-injected metalorganic chemical vapor deposition. The effect of the film thickness on the ferroelectric domain structure and the dielectric and ferroelectric properties were systematically investigated. Domain structure analysis of epitaxial PZT films was accomplished with high-resolution X-ray diffraction reciprocal space mapping and high-resolution transmission electron microscopy. Fully polar-axis (c-axis)-oriented epitaxial PZT thin films with high ferroelectric polarization values [e.g., remanent polarization (P _r) ~ 90 μC/cm²] were observed for film thicknesses below 70 nm. Films thicker than 70 nm had a c/a/c/a polydomain structure and the relative volume fraction of c-domains monotonously decreased to about 72% on increasing the film thickness up to 230 nm , and finally P _r diminished to about 64 μC/cm² for the 230-nm-thick epitaxial film. These polarization values were in good agreement with the estimated values taking into account the volume fraction of the c-axis-oriented domains while assuming a negligible contribution of 90° domain reorientation caused by an externally applied electric field.     

The Uncertainty in SCHF‐DT Thermal Conductivity Measurements of Lotus‐Type Porous Copper

Lotus‐type porous metals with many straight pores are attractive for use as heat‐sinks because a large heat‐transfer capacity can be obtained, due to the small diameter of the pores. In order to use lotus‐type porous copper effectively as a heat sink, it is important to know the effective thermal conductivity considering the effect of pores on heat conduction in the material. Since these metals have anisotropic pores, a steady‐state comparative longitudinal heat‐flow method for measuring thermal conductivity, referring to an ASTM standard, is better than other methods. So far, the effective thermal conductivity of lotus‐type porous copper has been measured by using specimens of different thickness (the SCHF‐DT method). In this paper, the uncertainty in the effective thermal conductivity of a specimen measured using this method was evaluated by comparison between numerical analysis and current experimental data. The following conclusions were drawn: 1) The uncertainty showed good agreement with the uncertainty analysis; 2) The contribution of the thermal grease thickness was large, based on a combined standard uncertainty analysis; and, 3) The effective thermal conductivity perpendicular to the pores of lotus copper can be measured within 10% uncertainty by this method.     

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.