This study investigated the feasibility of using Ag-TiO₂ photocatalyst supported on glass fiber (Ag-TiO₂/GF) prepared by a sol-gel method as an indoor air germicide. An experimental model was designed to investigate the bacterial disinfection efficiency of Staphylococcus (Staph), the most popular bacterium in hospitals in Korea, by the Ag-TiO₂/GF photocatalyst. The silver content in Ag/TiO₂ was altered from 1 to 10% to investigate the optimal ratio of Ag doped on TiO₂/glass fiber (TiO₂/GF) for photocatalytic disinfection of Staph. This study confirmed that Ag in Ag-TiO₂/GF could work as an electron sink or donor to increase photocatalytic activity and promote the charge separation of electron-hole pairs generated from TiO₂ after photon absorption. Ag also acts as an intermediate agent for the transfer of photo-generated electrons from the valence band of TiO₂ to an acceptor (O₂ gas) to promote photo-oxidation processes. The photocatalytic disinfection activity of Ag-TiO₂/GF under visible light increased with the increase in silver content up to 7.5% and then slightly decreased with further increasing silver content. The highest disinfection efficiency and disinfection capacity of Staph using 7.5% Ag-TiO₂/GF were 75.23% and 20 (CFU∙s⁻¹∙cm⁻²) respectively. The medium level of humidity of 60% ± 5% showed better photocatalytic disinfection than the lower (40% ± 5%) or higher (80% ± 5%) levels.

Indoor and outdoor ultrafine, accumulation mode, and coarse fractions collected at two preschools (S1 and S2) in Hanoi capital, Vietnam were characterized in terms of mass-size distribution and elemental composition to identify major emission sources. The sampling campaigns were performed simultaneously indoors and outdoors over four consecutive weeks at each school. Indoor average concentrations of CO₂ and CO at both schools were below the limit values recommended by American Society of Heating, Refrigerating and Air-Conditioning Engineers (1000 ppm for CO₂) and World Health Organization (7 mg/m³ for CO). Indoor concentrations of PM_2.5 and PM₁₀ at S1 and S2 were strongly influenced by the presence of children and their activities indoors. The indoor average concentrations of PM_2.5 and PM₁₀ were 49.4 µg/m³ and 59.7 µg/m³ at S1, while those values at S2 were 7.9 and 10.8 µg/m³, respectively. Mass-size distribution of indoor and outdoor particles presented similar patterns, in which ultrafine particles accounted for around 15–20% wt/wt while fine particles (PM_2.5) made up almost 80% wt/wt of PM₁₀. PM_2.5–10 did not display regular shapes while smaller factions tended to aggregate to form clusters with fine structures. Oxygen (O) was the most abundant element in all fractions, followed by carbon (C) for indoor and outdoor particles. O accounted for 36.2% (PM_0.5–1) to 42.4% wt/wt (PM_0.1) of indoor particles, while those figures for C were in the range of 14.5% (for PM_0.1) to 18.1% (for PM_1–2.5). Apart from O and C, mass proportion of other major and minor elements (Al, Ca, Cr, Fe , K, Mg, Si, Ti) could make up to 50%, whereas trace elements (As, Bi, Cd, Co, Cr, Cu, La, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sn, Sr, and Zn) accounted for less than 0.5% of indoor and outdoor airborne particles. There were no significant indoor emission sources of trace and minor elements. Traffic significantly contributed to major and trace elements at S1 and S2.

Herein, we reported the composite structure of LiMnO₂ and Li₂MnO₃ as a low-cost and environmentally benign cathode material. This composite with the main phase of LiMnO₂ (90) was synthesized by hydrothermal method at 220C from LiOH and Mn(CH₃COO)₂ precursors. The obtained nanosized LiMnO₂-LiMnO₃ cathode material exhibits a high capacity of 265mAhg^-1 at C/10. The incorporation of Li₂MnO₃ into the LiMnO₂ phase could stabilize the structure, leading to the improved cycle stability of the cathode. The capacity retention of the cathode was 93 after 80 cycles at C/2. Our results facilitate a potential strategy for developing high-performance cathode materials based on the Li-Mn-O system.