Experimental studies of particle removal and probability of COVID-19 infection in passenger railcars.

A series of experiments in stationary and moving passenger railcars was conducted to measure the removal rates of particles in the size ranges of SARS-CoV-2 viral aerosols, and the air changes per hour provided by the existing and modified air handling systems. The effect of ventilation and air filtration systems on removal rates and their effects on estimated probability (i.e., risk) of infection was evaluated in a range of representative conditions: (1) for two different ratios of recirculated air (RA) to outdoor air (OA) (90:10 RA:OA and 67:33 RA:OA); (2) using minimum efficiency reporting value (MERV) filters with standard (MERV-8) and increased (MERV-13) filtration ratings; and (3) in the presence and absence of a portable high-efficiency particulate-air (HEPA) room air purifier system operated at clean air delivery rate (CADR) of 150 and 550 cfm. The higher-efficiency MERV-13 filters significantly increased particle removal rates on average by 3.8 to 8.4 hr-1 across particle sizes ranging from 0.3 to 10 µm (p < 0.01) compared to MERV-8 filters. The different RA:OA ratios and the use of a portable HEPA air purifier system had little effect on particle removal rates. MERV-13 filters reduced the estimated probability of infection by 42% compared to the MERV-8 filter. The use of a HEPA-air purifier with a MERV-13 filter causes a 50% reduction in the estimated probability of infection. Upgrading the efficiency of HVAC filters from MERV-8 to MERV-13 in public transit vehicles is the most effective exposure control method resulting in a clear reduction in the removal rates of aerosol particles and the estimated probability of infection.

Beetroot improves oxidative stability and functional properties of processed foods: singular and combined effects with chocolate.

Oxidation is a significant problem in processed foods affecting their physico-chemical, shelf life and health properties. Natural antioxidants could be viable alternatives to synthetic variants for safely improving antioxidation properties of processed foods. The aim of this study was to assess the singular and combined effects of beetroot and chocolate on the oxidative stability of a high fat and protein processed food (sponge cake) during storage and gastrointestinal digestion. Cakes were prepared and assessed for antioxidant potential, polyphenols, and oxidative stability, and macronutrient oxidation during simulated gastro-intestinal digestion. Beetroot significantly improved the antioxidant and polyphenol profiles of sponge cake which further improved with chocolate addition. Beetroot also significantly increased the oxidative stability and shelf-life of sponge cake, and these effects were enhanced when combined with chocolate. Chocolate significantly reduced lipid oxidation during the gastric phase of digestion. However, both chocolate and beetroot did not curtail lipid oxidation in the intestinal phase, nor protein oxidation at any of the phases. Promisingly, beetroot and chocolate addition did not affect textural parameters and delayed staling by up to 2 days. Overall, the benefits of beetroot and chocolate addition were manifested more in the food system than during its digestion. Beetroot improves the oxidative stability and shelf life of processed foods, and its effects could be enhanced through combining with other natural products.

Clay mineral type effect on bacterial enteropathogen survival in soil.

Enteropathogens released into the environment can represent a serious risk to public health. Soil clay content has long been known to have an important effect on enteropathogen survival in soil, generally enhancing survival. However, clay mineral composition in soils varies, and different clay minerals have specific physiochemical properties that would be expected to impact differentially on survival. This work investigated the effect of clay materials, with a predominance of a particular mineral type (montmorillonite, kaolinite, or illite), on the survival in soil microcosms over 96 days of Listeria monocytogenes, Salmonella Dublin, and Escherichia coli O157. Clay mineral addition was found to alter a number of physicochemical parameters in soil, including cation exchange capacity and surface area, and this was specific to the mineral type. Clay mineral addition enhanced enteropathogen survival in soil. The type of clay mineral was found to differentially affect enteropathogen survival and the effect was enteropathogen-specific.