Estimation of Indoor Air PAH Concentration Increases by Cigarette,Incense-Stick,and Mosquito-Repellent-Incense Smoke

Smoke from cigarette smoking and burning of incense sticks and mosquito-repellent incense, which is particularly used in summer, are thought to be primary factors of indoor air pollution by polycyclic aromatic hydrocarbons (PAHs) in Japanese houses. In this study, these respective smokes as indoor air pollutants were evaluated by quantifying their particulate matter (PM) and 7 PAHs. PM and PAHs in smoke from 5 popular brands of Japanese cigarettes were collected on the glass fiber filter by the international smoking mode. PM was quantified by weighing the filter before and after trapping them. PAHs were analyzed by HPLC after extracting the filter with ethanol/benzene (1:3, by vol.). Similarly, evaluation of smoke respectively generated by natural burning of 4 brands of incense sticks and 3 brands of mosquito-repellent incenses was also conducted. As the results of these experiments, the average concentrations of PM and benzo[a]pyrene in a 35 m³ closed room were estimated to increase 1630 μg/m³ and 8.2 ng/m³, respectively, by smoking of 3 cigarettes; 1320 μ/m³ and 4.1 ng/m³, respectively, by burning of 2 incense sticks; and 2510 μg/m³ and 17.3 ng/m³, respectively, by burning of 8 cm of mosquito-repellent incense.     

Preparation of Hydrogen Permeable Membrane Using Nanoparticles Electrophoresis Technique

Hydrogen perm-selective membranes composed of Pd nanoparticles were investigated. The nanoparticles were prepared by ultrasonic reduction from Pd^II ions, and then deposited on a substrate disc with electrophoresis technique. These electrophoretic membranes have shown high performance of perm-selectivity for H₂ with separation factor α = 3.85, under room temperature.     

Deformation behaviors and fracture strength of β$\ubeta$-Si3N4 single crystals

In this study, the yield stress and fracture strength of $\beta$-Si₃N₄ single crystals were directly measured by bending tests of microcantilever beam specimens that were prepared by a focused ion beam method. The $\beta$-Si₃N₄ single crystals were plastically deformed at room temperature under high bending stress, and the yield stress depended on the crystal orientation. Transmission electron microscopy observation of the specimens after bending tests indicates that the plastic deformation resulted from dislocations in the primary slip system $\{10\overline{1}0\}$<0001>, and the critical resolved shear stress of this slip system determined from the yield stress was 1.34 GPa. The fracture strength of $\beta$-Si₃N₄ single crystals ranged approximately up to 20 GPa, depending on the crystal orientation as with the yield stress. The fracture behavior of $\beta$-Si₃N₄ single crystals was discussed in terms of the accumulation of dislocations.