Contrasting Lubrication Properties of Imidazolium-Based Ionic Liquids Affected by the Nature of the Surface Under High Vacuum

The lubrication performance of imidazolium-based ionic liquids was evaluated under high vacuum using a ball-on-disk tribometer. A ball and a flat disk made of SUS440C stainless steel were used as specimens. A surface of the as-received flat disk specimen was covered with a thick oxide layer (>40 nm). For an examination of the effect of the surface oxide layer on the tribological performance of the ionic liquids under high vacuum, another specimen with a thin oxide layer (approx. 4 nm thick) was prepared. The ionic liquids with the TFSA anion showed better lubrication performance with the thicker oxide layer specimen, whereas the ionic liquids with the BF4 anion showed superior performance with the thinner oxide layer specimen. These results are discussed based on the HSAB principle. It is shown that the mechanism of the opposite tribological characteristics can be reasonably explained in terms of the chemical hardness by the HSAB principle.     

Development and evaluation of qualitative detection methods for unapproved genetically modified rice (LLRice)

We developed a specific method to extract DNA from rice grain samples and modified the qualitative real-time PCR method provided by Bayer Co., Ltd. for reliable detection of the genetically modified (GM) rice variety, LLRice601, which has not undergone safety assessment for regulatory approval in Japan. Moreover, we conducted a data analysis to confirm the results obtained with real-time PCR. The yields of DNA extracted from powdered samples of rice grains were almost equal among 5 different varieties of rice, and there was no significant difference in the yield over three days. Reliable results were obtained using 50 ng of the extracted DNA as the template for real-time PCR. To examine the adequacy of the methods, we organized an interlaboratory study with the participation of 2 laboratories, in which 80 test samples were analyzed in a blinded manner. The statistical analysis revealed no significant difference in the Ct value for the endogenous gene of the DNA samples and for the targeted DNA sequence of 0.1% samples. The limit of detection of the method was approximately 0.1%. Analysis of the fluorescence intensity of the PCR-amplified product of the construct-specific DNA sequence suggested that it may be reasonable to judge a sample as positive when a Ct value of less than 40 is obtained.     

A novel estimating method for steering efficiency of the driver with electromyography signals

The existing research of steering efficiency mainly focuses on the mechanism efficiency of steering system, aiming at designing and optimizing the mechanism of steering system. In the development of assist steering system especially the evaluation of its comfort, the steering efficiency of driver physiological output usually are not considered, because this physiological output is difficult to measure or to estimate, and the objective evaluation of steering comfort therefore cannot be conducted with movement efficiency perspective. In order to take a further step to the objective evaluation of steering comfort, an estimating method for the steering efficiency of the driver was developed based on the research of the relationship between the steering force and muscle activity. First, the steering forces in the steering wheel plane and the electromyography （EMG） signals of the primary muscles were measured. These primary muscles are the muscles in shoulder and upper ann which mainly produced the steering torque, and their functions in steering maneuver were identified previously. Next, based on the multiple regressions of the steering force and EMG signals, both the effective steering force and the total force capacity of driver in steering maneuver were calculated. Finally, the steering efficiency of driver was estimated by means of the estimated effective force and the total force capacity, which represented the information of driver physiological output of the primary muscles. This research develops a novel estimating method for driver steering efficiency of driver physiological output, including the estimation of both steering force and the force capacity of primary muscles with EMG signals, and will benefit to evaluate the steering comfort with an objective perspective.     

Dietary salmon milt extracts attenuate hepatosteatosis and liver dysfunction in diet-induced fatty liver model

The cover image is based on the Research Article Dietary salmon milt extracts attenuate hepatosteatosis and liver dysfunction in diet-induced fatty liver model by Toshihiro Sakurai et al., DOI: 10.1002/jsfa.9352

     

An aqueous synthesis of photocatalyst by selective dissolution of titanium oxide/hydroxyapatite composite

A novel synthesis method of a highly active photocatalyst was proposed. Titanium dioxide (TiO₂) nano-particles were prepared by three-step procedure, precipitation of hydroxyapatite (HAp) on TiO₂ particles, heat treatment of the TiO₂/HAp composites, and acid treatment in hydrochloric acid. The unique point of this procedure is the selective dissolution of HAp to obtain exposed TiO₂ surfaces. The HAp precipitation was achieved by stirring TiO₂ powders in the mixtures of Ca(NO₃)₂ and NH₄H₂PO₄ aqueous solutions at pH 8.5. Then, the heat-treated TiO₂/HAp composites were treated with hydrochloric acid. The precipitated HAp avoided the direct contact of TiO₂ particles and suppressed the phase transformation from anatase-to-rutile >200 °C. The HAp also suppressed a decrease of specific surface area of TiO₂ during the heat treatment. The photocatalytic activities were evaluated from an absorbance decrease of methylene blue (MB) under ultraviolet (UV) irradiation. The MB photodecomposition was approximated to the first-order reaction and the reaction rate constants of the obtained TiO₂ powders heated at various temperatures were higher than those of conventional TiO₂ powders heated at same temperatures. The enhanced photocatalytic activity is attributed to the suppression effects for the phase transformation to rutile phase and the decreasing of specific surface area in the heat treatment.     

Initial stage of carbon nanotube formation process by surface decomposition of SiC: STM and NEXAFS study

Formation process of carbon nanocaps, which are formed at the beginning of carbon nanotube (CNT) growth by surface decomposition of SiC, was investigated by scanning tunneling microscopy (STM) and in situ near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. As Si atoms were desorbed, carbon nanoparticles 1-2 nm in diameter were accumulated on SiC(000-1) surfaces. At around 1200 °C, these were coalesced and crystallized to carbon nanocaps. In addition, just before the crystallization, majority of C-C bonds were directed nearly parallel to the surface. Based on these experimental results, we proposed a model for carbon nanocap formation, which plays an important role to determine the CNTs.     

Antireflective coating fabricated by chemical deposition of ZnO for spherical Si solar cells

ZnO thin films as an antireflective (AR) coating have been successfully fabricated on spherical Si solar cells by chemical deposition, which enables uniform film formation. ZnO films were prepared chemically by immersing the cell in an aqueous solution of zinc nitrate and dimethylamineborane maintained at 80 °C. The current–voltage measurements of the solar cells confirmed the increase in short circuit current induced by the AR effect. The open circuit voltage and fill factor were improved by surface passivation. As a result, the conversion efficiency of cells without an AR coating (9.45%) increased to 11.8%, which represents a 25% (relative) increase. The results indicate that the chemical deposition of ZnO is effective for the AR coating of spherical Si solar cells.     

Comparative study of photoinduced wettability conversion between [PW12O40]/brookite and [SiW12O40]/brookite hybrid films

Two tungsten-based Keggin-type heteropolyacids (PW₁₂: ([PW₁₂O₄₀]³⁻) and SiW₁₂: ([SiW₁₂O₄₀]⁴⁻)) were hybridized with brookite-type TiO₂. Then photocatalytic decomposition activity, photoinduced hydrophilicity, and sustainability of the hydrophilicity in the dark were evaluated using gaseous 2-propanol (IPA) decomposition and sessile drop method. The obtained films were transparent in the visible wavelength range. Both hybrid films exhibited higher photocatalytic decomposition activity and had higher photoinduced hydrophilicizing rates than pure brookite films under UV illumination. The PW₁₂/TiO₂ film exhibited better photocatalytic performance than the SiW₁₂/TiO₂ film did. Atmosphere dependence, XPS analysis, and electrochemical experiments indicated the cause of these two films' different levels of sustainability of hydrophilicity to be differences in their electron storage capability. Results show that the electron scavenger capability and reoxidation efficiency of the heteropolyacid are key factors affecting the overall performance of wettability conversion of this hybrid film system before and after UV illumination.