The Efficacy of Plant-Based Ionizers in Removing Aerosol for COVID-19 Mitigation

Small-sized droplets/aerosol transmission is one of the factors responsible for the spread of COVID-19,in addition to large droplets and surface contamination(fomites).While large droplets and surface contamination can be relatively easier to deal with(i.e.,using mask and proper hygiene measures),aerosol presents a different challenge due to their ability to remain airborne for a long time.This calls for mitigation solutions that can rapidly eliminate the airborne aerosol.Pre-COVID-19,air ionizers have been touted as effective tools to eliminate small particulates.In this work,we sought to evaluate the efficacy of a novel plant-based ionizer in eliminating aerosol.It was found that factors such as the ion concentration,humidity,and ventilation can drastically affect the efficacy of aerosol removal.The aerosol removal rate was quantified in terms of ACH(air changes per hour)and CADR-(clean air delivery rate-)equivalent unit,with ACH as high as 12 and CADR as high as 141 ft^(3)/minute being achieved by a plant-based ionizer in a small isolated room.This work provides an important and timely guidance on the effective deployment of ionizers in minimizing the risk of COVID-19 spread via airborne aerosol,especially in a poorly-ventilated environment.

Genome-wide Expansion and Expression Divergence of the Basic Leucine Zipper Transcription Factors in Higher Plants with an Emphasis on Sorghum

Plant bZIP transcription factors play crucial roles in multiple biological processes. However, little is known about the sorghum bZIP gene family although the sorghum genome has been completely sequenced. In this study, we have carried out a genome-wide identification and characterization of this gene family in sorghum. Our data show that the genome encodes at least 92 bZIP transcription factors. These bZIP genes have been expanded mainly by segmental duplication. Such an expansion mechanism has also been observed in rice, arabidopsis and many other plant organisms, suggesting a common expansion mode of this gene family in plants. Further investigation shows that most of the bZIP members have been present in the most recent common ancestor of sorghum and rice and the major expansion would occur before the sorghum-rice split era. Although these bZlP genes have been duplicated with a long history, they exhibited limited functional divergence as shown by nonsynonymous substitutions （Ka）lsynonymous substitutions （Ks） analyses. Their retention was mainly due to the high percentages of expression divergence. Our data also showed that this gene family might play a role in multiple developmental stages and tissues and might be regarded as important regulators of various abiotic stresses and sugar signaling.