关于龙安寺方丈庭园造园意图的考察

"龙安寺方丈庭园"是日本具有代表性的庭园,但其建造时期、建造者、建造意图都未有定论。本文认为此园是对中国五台山的描绘。自古以来五台山的文殊菩萨信仰非常兴盛,从8世纪开始有多位来自日本的高僧到访过五台山,并将佛像、绘画等带回了日本。以此为依据在13世纪绘制而成的"五台山文殊菩萨骑狮像",中央石峰的形态与"龙安寺方丈庭园"中央置石组群造型相同,可以推断"五台山文殊菩萨骑狮像"中的石峰是其描摹的原型。     

Fabrication of vertically aligned diamond whiskers from highly boron-doped diamond by oxygen plasma etching

Conductive diamond whiskers were fabricated by maskless oxygen plasma etching on highly boron-doped diamond substrates. The effects of the etching conditions and the boron concentration in diamond on the whisker morphology and overall substrate coverage were investigated. High boron-doping levels (greater than 8.4 × 10(20) cm(-3)) are crucial for the formation of the nanosized, densely packed whiskers with diameter of ca. 20 nm, length of ca. 200 nm, and density of ca. 3.8 × 10(10) cm(-2) under optimal oxygen plasma etching conditions (10 min at a chamber pressure of 20 Pa). Confocal Raman mapping and scanning electron microscopy illustrate that the boron distribution in the diamond surface region is consistent with the distribution of whisker sites. The boron dopant atoms in the diamond appear to lead to the initial fine column formation. This simple method could provide a facile, cost-effective means for the preparation of conductive nanostructured diamond materials for electrochemical applications as well as electron emission devices.     

Acceleration of nonylphenol and 4-tert-octylphenol degradation in sediment by Phragmites australis and associated rhizosphere bacteria

We investigated biodegradation of technical nonylphenol (tNP) in Phragmites australis rhizosphere sediment by conducting degradation experiments using sediments spiked with tNP. Accelerated tNP removal was observed in P. australis rhizosphere sediment, whereas tNP persisted in unvegetated sediment without plants and in autoclaved sediment with sterile plants, suggesting that the accelerated tNP removal resulted largely from tNP biodegradation by rhizosphere bacteria. Three bacterial strains, Stenotrophomonas sp. strain IT-1 and Sphingobium spp. strains IT-4 and IT-5, isolated from the rhizosphere were capable of utilizing tNP and 4-tert-octylphenol as a sole carbon source via type II ipso-substitution. Oxygen from P. australis roots, by creating highly oxygenated conditions in the sediment, stimulated cell growth and the tNP-degrading activity of the three strains. Moreover, organic compounds from P. australis roots functioned as carbon and energy sources for two strains, IT-4 and IT-5, supporting cell growth and tNP-degrading activity. Thus, P. australis roots elevated the cell growth and tNP-degrading activity of the three bacterial strains, leading to accelerated tNP removal. These results demonstrate that rhizoremediation of tNP-contaminated sediments using P. australis can be an effective strategy.     

Effect of an Nb2O5 nanolayer coating on ZnO electrodes in dye-sensitized solar cells

Nanostructured porous zinc oxide electrodes for use in dye-sensitized solar cells (DSSCs) were coated with thin niobium oxide layers by using sol–gel transformation of niobium pentaethoxide in air. Coating solutions were prepared by mixing niobium pentaethoxide and ethanol. A dip-coating technique was adopted at a low withdrawal speed of 100 μm s⁻¹. The coated electrodes were then heat-treated at temperatures between 400 and 600 °C. The presence of niobium in the coated electrodes was confirmed by X-ray photoelectron spectroscopy. As expected, the niobium oxide layers worked as an energy barrier between the ZnO electrode and electrolyte. Open-circuit voltage (V_OC) of the cells using the coated electrodes was then enhanced up to 0.768 V, which was attributable to the suppression of the recombination of photogenerated electrons with oxidized species in electrolytes. An additional benefit of the coating was that grain growth of ZnO particles in the electrodes was hindered and short-circuit photocurrent density (J_SC) was kept relatively high due to large amounts of adsorbed dye. An overall light-to-electricity conversion efficiency was increased to a maximum of 5.19%, indicating that the proper coating technique was the key for improving the performance of ZnO-based DSSCs.     

Decomposition characteristics of biodegradable plastics made from sago starch‐extraction residue

Biodegradable plastics were synthesized for the effective use of sago starch‐extraction residue, which has been discarded as a waste. Two types of esterified sago starch‐extraction residue, P‐SP and L‐SP, were obtained. It had black color for P‐SP₁₆₀ (esterified by palm oil) to light yellow color for L‐SP₈₀ (esterified by lauric acid) and showed high carbon content, ranging from 399.3 to 537.1 g kg⁻¹. Biodegradable plastics from the residue, which had high esterification degree showed thermoplasticity and slower decomposition in Andisols in Japan and Inceptisols in Philippines. The esterification degrees of P‐SP₁₆₀ and L‐SP were 3.23 and 2.95 to 5.18 mmol g⁻¹, respectively. In addition, L‐SP₈₀ exhibited the most appropriate thermal softening behavior by heating. The cumulative decomposition of P‐SP₁₆₀ in Andisols and Inceptisols showed 16.7 and 32.8% of total carbon during 31 day of the incubation. On the other hand, the decomposition rates of L‐SP₈₀ in Andisols and Inceptisols were less than 10% of total carbon during 31 day of the incubation. The addition of triacetin as plasticizer to P‐SP₁₆₀ and L‐SP₈₀ remarkably influenced the decomposition rate of both molded P‐SP₁₆₀ and L‐SP₈₀. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Disparities of indoor temperature in winter: A cross-sectional analysis of the Nationwide Smart Wellness Housing Survey in Japan

The WHO Housing and health guidelines recommend a minimum indoor temperature of 18°C to prevent cold-related diseases. In Japan, indoor temperatures appear lower than in Euro-American countries because of low insulation standards and use of partial intermittent heating. This study investigated the actual status of indoor temperatures in Japan and the common characteristics of residents who live in cold homes. We conducted a nationwide real-world survey on indoor temperature for 2 weeks in winter. Cross-sectional analyses involving 2190 houses showed that average living room, changing room, and bedroom temperatures were 16.8°C, 13.0°C, and 12.8°C, respectively. Comparison of average living room temperature between prefectures revealed a maximum difference of 6.7°C (Hokkaido: 19.8°C, Kagawa: 13.1°C). Compared to the high-income group, the odds ratio for living room temperature falling below 18°C was 1.38 (95% CI: 1.04-1.84) and 2.07 (95% CI: 1.28-3.33) for the middle- and low-income groups. The odds ratio was 1.96 (95% CI: 1.19-3.22) for single-person households, compared to households living with housemates. Furthermore, lower room temperature was correlated with local heating device use and a larger amount of clothes. These results will be useful in the development of prevention strategies for residents who live in cold homes.     

Adhesion Properties of Nanometer-Thick Perfluoropolyether Films Confined Between Solid Surfaces: A Coarse-Grained Molecular Dynamics Study

Lubrication with thin liquid films is essential to ensure the tribological reliability of technologically advanced devices, such as micro-electro-mechanical systems and hard disk drives. However, the adhesion and friction properties of thin films and the underlying mechanism remain elusive due to our limited understanding of film structures and motions at the molecular scale. Here, we investigate the adhesion behavior of nanometer-thick perfluoropolyether (PFPE) films confined between two solid surfaces as a function of film thickness using coarse-grained molecular dynamics simulations. Consistent with typical experimental results, our simulations show that the adhesive force exerted by the PFPE films reaches a maximum and then decreases with increasing solid–solid spacing. The maximum adhesive force increases sharply for PFPE films thinner than 4 nm. When exhibiting the maximum adhesive force, PFPE films are slightly stretched within a solid–solid spacing a little larger than the initial film thickness and thereby show lower density than the original equilibrium density. Conventional theories of adhesion, which assume equilibrium density for liquid films, are not applicable in such case. Therefore, we construct a theoretical model that takes decreasing liquid density into account to discuss the underlying mechanism of the adhesive force exerted by nanometer-thick PFPE films on solid surfaces. We infer from the theoretical analyses that the maximum adhesive force originates mainly from solid–liquid interaction for thin films and liquid–liquid interaction for thick films.     

New Frontiers in Materials Science Opened by Ionic Liquids

Ionic liquids (ILs) including ambient‐temperature molten salts, which exist in the liquid state even at room temperature, have a long research history. However, their applications were once limited because ILs were considered as highly moisture‐sensitive solvents that should be handled in a glove box. After the first synthesis of moisture‐stable ILs in 1992, their unique physicochemical properties became known in all scientific fields. ILs are composed solely of ions and exhibit several specific liquid‐like properties, e.g., some ILs enable dissolution of insoluble bio‐related materials and the use as tailor‐made lubricants in industrial applications under extreme physicochemical conditions. Hybridization of ILs and other materials provides quasi‐solid materials, which can be used to fabricate highly functional devices. ILs are also used as reaction media for electrochemical and chemical synthesis of nanomaterials. In addition, the negligible vapor pressure of ILs allows the fabrication of electrochemical devices that are operated under ambient conditions, and many liquid‐vacuum technologies, such as X‐ray photoelectron spectroscopy (XPS) analysis of liquids, electron microscopy of liquids, and sputtering and physical vapor deposition onto liquids. In this article, we review recent studies on ILs that are employed as functional advanced materials, advanced mediums for materials production, and components for preparing highly functional materials.     

Metal release from stainless steel, Co–Cr–Mo–Ni–Fe and Ni–Ti alloys in vascular implants

A seven-day immersion test using several solutions was conducted on stainless steel, Co-based alloy, and Ni–Ti alloy, which are used for stents and stent grafts. The quantitative data on the release of each metal ion and the correlation between metal ion release rate and pH were obtained. The quantities of Fe and Ni released from stainless steel gradually decreased with increasing solution pH (pH 2–7.5). For Co–Cr–Mo–Ni–Fe alloy, the quantity of Cr released steadily increased as pH decreased (pH ≤ 6) and reached nearly zero at pHs higher than 6 (pH 6–7.5). Co release was slightly affected by a variation in pH. The quantities of Ni and Ti released from Ni–Ti alloy markedly increased with decreasing pH (pH ≤ 4) and they leveled off from pH 4 (pH 4–7.5). Although the rapid increases were observed at approximately pH 2, the quantities were even higher than that of Co released from the Co–Cr–Mo and Co–Cr–Mo–Ni–Fe alloys. For further investigation of the rapid increase in the quantities of metals released at pH 2, an anodic polarization test was employed to study the passive and transpassive behaviours of Ni–Ti alloy. The critical current density for the passivation of Ni–Ti alloy markedly increased as pH decreased (pH ≤ 4) and was low (1.4 μA/cm²) at pH higher than 4 (pH 4–7.5). The potential at a current density of 10 μA/cm², by contrast, markedly rose with decreasing pH (pH ≤ 2), and was 1.2 V from pH 2 (pH 2–7.5).     

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.