Electricity production performance enhancement of microbial fuel cells with double-layer sodium alginate hydrogel bioanodes driven by high-salinity waste leachate.

The poor bacterial loading capacity and biocompatibility of the anode lead to weak electricity production performance of microbial fuel cells (MFCs). Inspired by kelp, we developed a double-layer hydrogel bioanode based on sodium alginate (SA). The inner hydrogel layer of encapsulated Fe3O4 and electroactive microorganisms (EAMs) was used as the bioelectrochemical catalytic layer. The outer hydrogel layer formed by cross-linking SA with polyvinyl alcohol (PVA) was used as the protective layer. The 3D porous structure of the inner hydrogel formed based on Fe3O4 facilitated the electroactive bacteria colonization and electron transfer, while the high structural toughness, salt-resistance and antibacterial properties of the outer highly cross-linked hydrogel served to protect the catalytic layer for stable electricity production. When high-salt waste leachate was used as the nutrient, the amazing open-circuit voltage (OCV) of 1.17 V and the operating voltage of 781 mV were brought by the double-layer hydrogel bioanode PVA@SA&Fe3O4/EAMs@SA.

Three Experimental Common High-Risk Procedures: Emission Characteristics Identification and Source Intensity Estimation in Biosafety Laboratory.

Biosafety laboratory is an important place to study high-risk microbes. In biosafety laboratories, with the outbreak of infectious diseases such as COVID-19, experimental activities have become increasingly frequent, and the risk of exposure to bioaerosols has increased. To explore the exposure risk of biosafety laboratories, the intensity and emission characteristics of laboratory risk factors were investigated. In this study, high-risk microbe samples were substituted with Serratia marcescens as the model bacteria. The resulting concentration and particle size segregation of the bioaerosol produced by three experimental procedures (spill, injection, and sample drop) were monitored, and the emission sources' intensity were quantitatively analyzed. The results showed that the aerosol concentration produced by injection and sample drop was 103 CFU/m3, and that by sample spill was 102 CFU/m3. The particle size of bioaerosol is mainly segregated in the range of 3.3-4.7 µm. There are significant differences in the influence of risk factors on source intensity. The intensity of sample spill, injection, and sample drop source is 3.6 CFU/s, 78.2 CFU/s, and 664 CFU/s. This study could provide suggestions for risk assessment of experimental operation procedures and experimental personnel protection.

Quantitative distribution of human exhaled particles in a ventilation room.

Respiratory viruses can be attached to human exhaled particles and spread from person to person through respiratory activities. The purpose of this study is to obtain the quantitative description formula of human exhaled particles in the ventilated room through amount number of numerical simulation calculations and regression statistical analysis of the simulated data. In this study, a combination of numerical simulation and laboratory experiments was used, and the results were tallied preferably. Bacillus subtilis was released as a release source to investigate the migration and distribution of bioaerosol. The results show that under the condition of high air supply velocity, due to the disturbance of human respiration and airflow, the diffusion velocity of exhaled particles was faster and the diffusion range is larger than that of low air supply velocity within the same time frame. No matter where the location of the manikin was in the room, the exhaled particles would spread to the whole room in at least 900 s. The method used in this study could be used to predict the distribution of human exhaled particles concentration in different indoor spaces, such as public transport and hospitals. These findings could provide valuable reference for the location of indoor air purifiers, which plays a guiding role in the construction of a healthy indoor environment.

Cold Stress Resistance of Tomato (Solanum lycopersicum) Seedlings Is Enhanced by Light Supplementation From Underneath the Canopy.

Adverse environmental conditions, such as low temperature (LT), greatly limit the growth and production of tomato. Recently, light-emitting diodes (LEDs) with specific spectra have been increasingly used in horticultural production facilities. The chosen spectrum can affect plant growth, development, and resistance, but the physiological regulatory mechanisms are largely unknown. In this study, we investigated the effects of LED light supplementation (W:B = 2:1, light intensity of 100 µmol⋅m-2⋅s-1, for 4 h/day from 9:00 to 13:00) from above and below the canopy on tomato resistance under sub-LT stress (15/8°C). The results showed that supplemental lighting from underneath the canopy (USL) promoted the growth of tomato seedlings, as the plant height, stem diameter, root activity, and plant biomass were significantly higher than those under LT. The activity of the photochemical reaction center was enhanced because of the increase in the maximal photochemical efficiency (F v /F m ) and photochemical quenching (qP), which distributed more photosynthetic energy to the photochemical reactions and promoted photosynthetic performance [the maximum net photosynthetic rate (Pmax) was improved]. USL also advanced the degree of stomatal opening, thus facilitating carbon assimilation under LT. Additionally, the relative conductivity (RC) and malondialdehyde (MDA) content were decreased, while the soluble protein content and superoxide dismutase (SOD) activity were increased with the application of USL under LT, thereby causing a reduction in membrane lipid peroxidation and alleviation of stress damage. These results suggest that light supplementation from underneath the canopy improves the cold resistance of tomato seedlings mainly by alleviating the degree of photoinhibition on photosystems, improving the activity of the photochemical reaction center, and enhancing the activities of antioxidant enzymes, thereby promoting the growth and stress resistance of tomato plants.