Photo-induced super-hydrophilic property and photocatalysis on transparent Ti-containing mesoporous silica thin films

The transparent Ti-containing mesoporous silica thin films can be prepared on quartz plate using a spin-coating sol–gel method. The spectroscopic characterization has revealed that the Ti-containing mesoporous silica thin films contain isolated and tetrahedrally-coordinated titanium oxide moieties in the frameworks. Compared with the common mesoporous silica thin films, these Ti-containing mesoporous silica thin films have demonstrated a strong hydrophilic surface property even before UV-irradiation. After UV-light irradiation, the contact angle of water droplet on the Ti-containing mesoporous silica thin films became lower, indicating the appearance of the super-hydrophilic property. Under UV-light irradiation Ti-containing mesoporous silica thin films also exhibited highly selective activity for the photocatalytic oxidation of propylene. The isolated and tetrahedrally-coordinated titanium oxide moieties are responsible for these photo-induced surface reactions.     

Degradation mechanisms of poly(ethylene terephthalate) tire yarn

In order to clarify the fatigue mechanism of PET tire cords in rubber focusing on chemical degradation, hydrolysis in saturated steam atmosphere, ammonolysis in ammonia gas, and the degradation of the cords embedded in rubber have been studied at high temperature conditions. It was found that the strength loss of polyester tire cords in rubber has linear correlation with the amount of chemically induced chain scissions mainly caused by hydrolysis catalyzed by amines.     

Development of Broadband Telecommunications System for Railways Using Laser Technology

We developed a high‐speed telecommunication system for use on railways to improve customer service and the efficiency of operator's telecommunications between ground facilities and trains under operation. We built a mobile telecommunication system, capable of achieving a transfer rate of 1 Gbps in theory, by utilizing laser beam communications technology. We carried out a field test using trains in active service, and obtained results in which a transfer rate of approximately 700 Mbps in the TCP layer was achieved between the ground and a train running at a speed of approximately 130 km/h .     

Real‐time up‐converter from HDTV to 4K with super‐resolution: Breaking the Nyquist frequency barrier

This real‐time up‐converter from high‐definition television (HDTV) to 4K with a novel super‐resolution (SR) creates 4K video with frequency elements higher than the Nyquist frequency of the original HDTV video. The novel SR uses non‐linear signal processing to overcome the theoretical limitation of the Nyquist frequency.     

Differentiating stem cells on patterned substrates for neural network formation

Both 3D topographic and 2D adhesive network patterns were used to guide the growth and differentiation of embryonic and mesenchymal stem cells towards a neurogenic lineage. In the case of topographic patterns, lattices composed of square micro-wells for single cell trapping combined with connection channels for neurite outgrowth guidance were designed, with optimal conditions being obtained with large well sizes and short channel lengths. In the case of adhesive micro-contact printed patterns, a similar network design can be applied, but the “well” size should be significantly smaller. Our results also proved the neuron-like characteristics of the induced cellular networks.     

Shield Tunnel Construction in Centrifuge

A large number of centrifuge model tests for simulating the shield construction process in dry sand was carried out by using a newly developed 100 mm diameter miniature shield tunnel. Different construction processes were modeled by three series of tests. A “buried tube test” was conducted to measure the lining stress under a centrifugal acceleration, a “tail void test” simulated the process of tail void formation only, and a “shield test” dealt with the complete process of shield construction. Lining stresses, transverse and longitudinal surface settlements, and earth pressures around the tunnel were simultaneously measured during advancement of the shield at a centrifugal acceleration of 25g. The lining stress at the crown elevation was well predicted by Terzaghi's loosening earth pressure. From the comparison with the recent field measurements and the comparative results of three series of tests, it was confirmed that the shield construction process was successfully simulated in a centrifuge. An experimental formula for estimating the surface settlement above the shield was deduced by a function of tail void thickness and cover-to-diameter ratio.     

Indene Compounds Synthetically Derived from Vitamin D Have Selective Antibacterial Action on Helicobacter pylori

Helicobacter pylori infects the human stomach and is closely linked with the development of gastric cancer. When detected, this pathogen can be eradicated from the human stomach using wide‐spectrum antibiotics. However, year by year, H. pylori strains resistant to the antibacterial action of antibiotics have been increasing. The development of new antibacterial substances effective against drug‐resistant H. pylori is urgently required. Our group has recently identified extremely selective bactericidal effects against H. pylori in (1R,3aR,7aR)‐1‐[(1R)‐1,5‐dimethylhexyl]octahydro‐7a‐methyl‐4H‐inden‐4‐one (VDP1) (otherwise known as Grundmann's ketone), an indene compound derived from the decomposition of vitamin D₃ and proposed the antibacterial mechanism whereby VDP1 induces the bacteriolysis by interacting at least with PtdEtn (dimyristoyl‐phosphatidylethanolamine [di‐14:0 PtdEtn]) retaining two 14:0 fatty acids of the membrane lipid constituents. In this study, we synthesized new indene compounds ((1R,3aR,7aR)‐1‐((2R,E)‐5,6‐dimethylhept‐3‐en‐2‐yl)‐7a‐methyloctahydro‐4H‐inden‐4‐one [VD2‐1], (1R,3aR,7aR)‐1‐((S)‐1‐hydroxypropan‐2‐yl)‐7a‐methyloctahydro‐1H‐inden‐4‐ol [VD2‐2], and (1R,3aR,7aR)‐7a‐methyl‐1‐((R)‐6‐methylheptan‐2‐yl)octahydro‐1H‐inden‐4‐ol [VD3‐1]) using either vitamin D₂ or vitamin D₃ as materials. VD2‐1 and VD3‐1 selectively disrupted the di‐14:0 PtdEtn vesicles without destructing the vesicles of PtdEtn (dipalmitoyl‐phosphatidylethanolamine) retaining two 16:0 fatty acids. In contrast, VD2‐2, an indene compound lacking an alkyl group, had no influence on the structural stability of both PtdEtn vesicles. In addition, VD2‐1 and VD3‐1 exerted extremely selective bactericidal action against H. pylori without affecting the viability of commonplace bacteria. Meanwhile, VD2‐2 almost forfeited the bactericidal effects on H. pylori. These results suggest that the alkyl group of the indene compounds has a crucial conformation to interact with di‐14:0 PtdEtn of H. pylori membrane lipid constituents whereby the bacteriolysis is ultimately induced.     

Thermoelectric Properties of a 593-nm Individual Bismuth Nanowire Prepared Using a Quartz Template

An individual bismuth nanowire sample, 593 nm in diameter and 1.64 mm in length, has been successfully grown using a quartz template. The resistivity and the Seebeck coefficient of the nanowire at 300 K were 1.35 μΩ m and −59 μV/K, respectively, similar to those of a bismuth bulk sample. The temperature dependence of the resistivity was found to decrease with temperature from 300 K to 175 K and then increase with further temperature reduction below 175 K. The absolute value of the Seebeck coefficient decreased with temperature from 300 K to 90 K, and the sign of the Seebeck coefficient changed from negative to positive near 90 K. This result indicated that there was a small amount of contamination in the bismuth. The carrier density was estimated from the resistivity and Seebeck coefficient on the basis of limitation of the mean free path and a two-carrier model, and the observed temperature dependences are discussed.     

Prevention of Cracks in Functionally Graded SiO2‐Mo Materials Fabricated by Uniaxial Compression Casting and Pressureless Sintering

In industrial high‐intensity discharge lamps, cracks and delaminations occasionally develop at the interface between SiO₂ and the Mo foil in the seal. Here, functionally graded SiO₂‐Mo materials for use in these lamps were fabricated by uniaxial compression casting and pressureless sintering. Consequently, vertical cracks developed across the sintered body layers, and interfacial cracks developed between the 100 wt% SiO₂ and 90 wt% SiO₂‐Mo layers. Therefore, the effects of residual stress, difference in the coefficient of thermal expansion (CTE), and difference in the volume shrinkage on these cracks were investigated. Vertical cracks were suppressed when residual stress was relaxed by annealing near the annealing point of silica glass during the cooling step in the sintering process. Interfacial cracks were suppressed when the difference in the CTE of the interface between the 100 wt% SiO₂ and 90 wt% SiO₂‐Mo layers was relaxed by inserting layers of 95 wt% SiO₂‐Mo between them. Furthermore, the suppression effect became stronger when the difference in the volume shrinkage of the layers was relaxed by sintering to join the separately sintered monolayers. Thus, the development of these cracks was influenced by the residual stress, CTE, and volume shrinkage. Therefore, these cracks can be prevented by optimizing these factors.     

UV excitation thermal lens microscope for sensitive and nonlabeled detection of nonfluorescent molecules

An ultrasensitive and nonlabeled detection method of nonfluorescent molecules on a microchip was developed by realizing a thermal lens microscope (TLM) with a 266-nm UV pulsed laser as an excitation light source (UV-TLM). Pulsed laser sources have advantages over continuous-wave laser sources in more compact size and better wavelength tuning, which are important for microchip-based analytical systems. Their disadvantage is difficulty in applying a lock-in amplifier due to the high (>10(4)) duty ratio of pulse oscillation. To overcome this problem, we realized a quasi-continuous-wave excitation by modulating the pulse trains at approximately 1 kHz and detecting the synchronous signal with a lock-in amplifier. The optimum pulse repetition frequency was obtained at 80 kHz, which was reasonable considering thermal equilibrium time. Furthermore, a permissible flow velocity in the range of 6.6-19.8 mm/s was found to avoid sensitivity decrease due to photochemical reactions and thermal energy dissipation. Under these conditions, we detected adenine aqueous solutions on a fused-silica microchip without labeling and obtained a sensitivity that was 350 times higher than that in a spectrophotometric method. The sensitivity was enough for detection on a microchip with an optical path length that was 2-3 orders shorter than that in conventional cuvettes. Finally, the UV-TLM method was applied to liquid chromatography detection. Fluorene and pyrene were separated in a microcolumn and detected in a capillary (50-microm inner diameter) with 150 times higher sensitivity than a spectrophotometric method. Our method provides highly sensitive and widely applicable detections for various analytical procedures and chemical syntheses on microchips.