Multipoint gas-liquid phase detection method based on a thin-film optical waveguide.

Gas-liquid phase detection is an important technique applied in a wide range of industries. In this study, we developed a phase detection method using a film-based optical waveguide. The optical waveguide is a thin and flexible film with multi-light paths that uses multi-microsensors for gas-liquid phase detection. The intensity of the reflected light generated by different refractive indices between gas and liquid aids in distinguishing the phase. Additionally, the sensing principle is identical to that of the typical optical fiber probing technique. In this study, we investigated the detection process considering the impact of a single droplet on waveguide sensors. Furthermore, we analyzed a droplet evaporation phenomenon and a thin-film liquid flow accompanied by a high-speed airflow on the sensors. Based on the obtained results, we determined that the proposed method can effectively measure the simultaneous local multipoint and high temporal resolution phase detection on a smooth surface. Therefore, we believe that our original sensor can diagnose such a dispersed two-phase flow near the wall inside of machines or curved tubes where the high-speed visualization is hard to be applied.

Electrodeless hydrogen production from seawater using femtosecond laser pulses.

This study presents the first experimental evidence of direct H2 production from seawater without harmful gas emissions (e.g., CO2, Cl2), which uses multiphoton ionization water splitting with a femtosecond pulse laser. According to H2 analysis using a gas chromatograph, the H2 production rate in seawater was 70 µmol h-1, which was approximately 3.3 times more than the ultrapure water case reported in the literature. This positive effect derives from focusing through the cuvette wall and the more significant Kerr effect in seawater. Such ion enhancement was observed in the case of seawater and diluted seawater compared with the ultrapure water case, but excessive salt can lead to ion suppression and adverse effects. These differences in salinity suggest appearances of nonlinear optical effects near the focal point and ionization of metallic elements with low ionization potential and are discussed in relation to results of bubble visualization, gas composition analysis, and pressure measurement in gaseous products.

Removing Gas from a Closed-End Small Hole by Irradiating Acoustic Waves with Two Frequencies.

Filling microstructures in the air with liquid or removing trapped gases from a surface in a liquid are required in processes such as cleaning, bonding, and painting. However, it is difficult to deform the gas-liquid interface to fill a small hole with liquid when surface tension has closed one end. Therefore, it is necessary to have an efficient method of removing gas from closed-end holes in liquids. Here, we demonstrate the gas-removing method using acoustic waves from small holes. We observed gas column oscillation by changing the hole size, wettability, and liquid surface tension to clarify the mechanism. First, we found that combining two different frequencies enabled complete gas removal in water within 2 s. From high-speed observation, about half of the removal was dominated by droplet or film formation caused by oscillating the gas column. The other half was dominated by approaching and coalescing the divided gas column. We conclude that the natural frequency of both the air column and the bubbles inside the tube are important.

[Clinical availability of the herbal medicine, SYOUSAIKOTOU, as a gargling agent for prevention and treatment of chemotherapy-induced stomatitis].

The stomatitis accompanying chemotherapy reduces a patient's QOL. Many reports have suggested that some kinds of gargling agents for oral mucositis shorten the duration and severity of symptoms. This study tested the prevention and efficacy against stomatitis of a herbal medicine (Syousaikotou) as a gargling agent for patients receiving chemotherapy. Compared to gargling with providone-iodine and amphotericin B, the Syousaikotou gargle showed a significantly decreased incidence of stomatitis, and a painkilling effect. Stomatitis occurred in about 17.4% among 23 chemotherapy cycles with the Syousaikotou gargle, against about 40.8% among 71 chemotherapy cycles without the Syousaikotou gargle. Among the patients suffering stomatitis pain after 22 chemotherapy cycles, the painkilling effect was seen to be 76.2%, and continues for about 2 hours. Critical side effects were not seen, but in 4 cases there were complaints about foul smells, such as oil and grass smells. Syousaikotou gargle was considered to be one of the useful methods against the stomatitis prevention and sharp pain mitigation from the chemotherapy.