Determination of the structure of liquids containing free radical molecules: Inter-molecular correlations in liquid chlorine dioxide

New Countermeasures Against Infections with/after COVID-19: Is Chlorine Dioxide a Useful and Safe Disinfectant?

Pandemics of microorganism are serious problem such as corona virus induced disease 2019(COVID-19), and the infectious diseases rapidly transmitted via airborne or aerosol among community space. To prevent aerosol infections, ozone and chlorine dioxide gases are practical methods in room air. However, ozone requires relatively high concentrations for this purpose, which might be toxic to humans present in the room. On the other hand, the low concentration of chlorine dioxide gas and aqueous solution are sufficiently effective against aerosol infection for the causative microorganism, and it is expected that when it is used in combination with a high-efficiency particulate air filter, it will be highly safe with high prevention effect and cost effectiveness.

Characterization of pharmaceuticals and personal care products as N-nitrosodimethylamine precursors during disinfection processes using free chlorine and chlorine dioxide

The worldwide detection of pharmaceuticals and personal care products (PPCPs) in aquatic environment and drinking water has caused wide concern in recent years. The possibility for concurrent formation of N-nitrosodimethylamine (NDMA) during disinfection has become another significant concern for water quality. This study demonstrates that a group of PPCPs containing amine groups can serve as NDMA precursors during free chlorine or chlorine dioxide (ClO2) chlorination processes. Selected PPCPs after screening by NDMA yield were further investigated for NDMA formation conditions. High disinfectant dose and initial PPCP concentration resulted in relatively high NDMA formation potential. Linear kinetic models were developed for NDMA formation during chlorination of selected PPCPs. Although the PPCP precursors were removed significantly during chlorination, they were not completely mineralized based on the total organic carbon (TOC) loss. The existence of another possible pathway for direct formation of NDMA from tertiary amine during chlorination was indicated, in which dimethylamine (DMA) was not involved. It is recommended to control the initial PPCP concentrations prior to disinfection and to shorten the contact time to reduce the NDMA formation. ClO2 is suggested to be a proper disinfectant in order to reduce the NDMA formation.

Inter-molecular correlations in liquid Se2Br2

The structure of molecular liquid Se2Br2 was analyzed by means of reverse Monte Carlo structural modeling, using a calculation based on high-energy x-ray diffraction data. It was found that, between the optical isomers of L and D types, the number of L-D neighboring molecular pairs increases, while that of the L-L and D-D pairs decreases with increasing temperature. From this temperature dependence and from the relaxation mode analysis of quasi-elastic neutron scattering spectra, it is reasonable to assume that the presence of L-D pairs relates to genuine inter-molecular interactions while the L-L and D-D pairs appear due to geometrical packing of the gauche-shaped molecules.