ABSTRACT
As human health concerns over disinfection byproducts (DBP) in drinking water increase, so does the need to develop new materials that remove them rapidly and at high capacity. Ion exchange (IEX) is an effective method for the removal of natural organic matter (NOM), especially anion exchange resins (AERs) with quaternary ammonium functional groups. However, capacity is limited in existing commercial resin materials because adsorbates can only interact with the outermost surface area, which makes these products inefficient on a mass basis. We have synthesized a novel "NanoResin" exploiting the enhanced NOM removal of the quaternary ammonium resin while utilizing the vast surface area of SWCNTs, which act as scaffolding for the resin. Our nanomaterials show increased adsorption capacity compared to commercially available adsorbents, in a fraction of the time. This NanoResin requires only about 10 s to reach ion-exchange equilibrium. Comparatively, commercial AERs only achieved partial removal after more than 30 min. High capacity adsorption of a low molecular weight (MW) surrogate has been measured. NOM removal was demonstrated in solutions of both low and high specific UV absorbance (SUVA) composition with these nanomaterials. Additionally, the NanoResin showed enhanced removal of a NOM concentrate sample taken from Myrtle Beach, SC, demonstrating NanoResin is an effective method of removal for refractory NOM in a natural aqueous environment. Synthesis and characterization of the polymers and nanomaterials are presented below. Adsorption capacity, adsorption kinetics, and the regeneration and reusability of these new materials for NOM removal are described. The open matrix microstructure precludes any intraparticle diffusion of adsorbates; thus, these nanomaterials act as a "contact resin".
ABSTRACT
Genome replication by the baculovirus DNA polymerase often generates errors in mononucleotide repeat (MNR) sequences due to replication slippage. This results in the inactivation of genes that affects different stages of the cell infection cycle. Here we mapped these MNRs in the 59 baculovirus genomes. We found that the MNR frequencies of baculovirus genomes are different and not correlated with the genome sizes. Although the average A/T content of baculoviruses is 58.67%, the A/T MNR frequency is significantly higher than that of the G/C MNRs. Furthermore, the A7/T7 MNRs are the most frequent of those we studied. Finally, MNR frequencies in different classes of baculovirus genes, such as immediate early genes, show differences between baculovirus genomes, suggesting that the distribution and frequency of different MNRs are unique to each baculovirus species or strain. Therefore, the results of this study can help select appropriate baculoviruses for the development of biological insecticides.
