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SARS-CoV-2 is the causative agent of COVID-19, which is a global pandemic. SARS-CoV-2 is transmitted rapidly via contaminated surfaces and aerosols, emphasizing the importance of environmental disinfection to block the spread of virus. Ultraviolet C radiation and chemical compounds are effective for SARS-CoV-2 disinfection, but can only be applied in the absence of humans due to their toxicities. Therefore, development of disinfectants that can be applied in working spaces without evacuating people is needed. Here we showed that TiO2-mediated photocatalytic reaction inactivates SARS-CoV-2 in a time-dependent manner and decreases its infectivity by 99.9% after 20 min and 120 min of treatment in aerosol and liquid, respectively. The mechanistic effects of TiO2 photocatalyst on SARS-CoV-2 virion included decreased total observed virion count, increased virion size, and reduced particle surface spike structure, as determined by transmission electron microscopy. Damage to viral proteins and genome was further confirmed by western blotting and RT-qPCR, respectively. The multi-antiviral effects of TiO2-mediated photocatalytic reaction implies universal disinfection potential for different infectious agents. Notably, TiO2 has no adverse effects on human health, and therefore, TiO2-induced photocatalytic reaction is suitable for disinfection of SARS-CoV-2 and other emerging infectious disease-causing agents in human habitation.

In this proceeding, a new proposal aiming to improve the precision of the proton Zemach radius will be presented. A circularly polarized laser will be shed on a sample of muonic hydrogen in its ground state. By observing the maximum muon decay asymmetry during scanning laser wave length, the ground-state hyperfine splitting energy can be identified, which is directly related to Zemach radius. 1 The precision of Zemach radius by this measurement is estimated to be three times better compared to PSI experiment. This result will contribute to the solution of proton size puzzle.

We report a sporadic sodium layer (SSL), in particular its fine structure, observed at 92–98 km between 20:00 and 23:30 UT (21:00–24:30 LT) on 11 January 2011 using a sodium lidar, which was installed in the European incoherent scatter (EISCAT) radar site at Tromsø, Norway (69.6°N, 19.2°E) in early 2010. The sodium lidar measurement with 5‐sec time‐resolution reveals the details of dramatic sodium‐density increase as well as short‐period wavelike structure in the SSL. The rate of increase of height‐integrated sodium density at the beginning of the SSL event was 6.4–9.6 × 1010 m−2 s−1. Dominant oscillation periods in the wavelike structures were 7–11 min at 95–98 km and 3 min at 92–95 km. The calculated power spectral densities are well represented by power laws, implying the presence of the short‐period waves and turbulence in the frequency range of 10−4–10−1 Hz.

[1] Using a simultaneous and common-volume observation by a European incoherent scatter (EISCAT) VHF radar and a sodium lidar at Tromsø, Norway (69.6 ı N, 19.2 ı E), we have determined, for the first time, the effect of pure particle precipitation, excluding that of the electric field, on sodium density variations. Our observation on 24-25 January 2012 showed that sodium atom density decreased when there was no ion temperature enhancement (indicating a weak electric field) and the electron density increased (indicating strong particle precipitation). From the results, we have concluded that auroral particle precipitation induced sodium atom density decrease in this event. Furthermore, a discussion is provided regarding the time response of the decrease in sodium density. Citation: Tsuda, T. T., et al. (2013), Decrease in sodium density observed during auroral particle precipitation over Tromsø, Norway, Geophys. Res. Lett., 40,[4486][4487][4488][4489][4490]