Gas/Particle Partition Measurements of PAH at Hazelrigg,U.K.

During September and October, 1998, the new Integrated Organic Gas and Particle Sampler (IOGAPS), was operated at Hazelrigg, UK, the field measurement station of the University of Lancaster. Gas/particle partition ratios of twenty-two 2–5 ring PAH were determined using both the IOGAPS (in which the gas phase is collected before the particle phase) and a low flow sampler which utilized the traditional filter-sorbent geometry. For compounds of intermediate volatility, less partitioning to the gas phase was observed when the denuder was used. The denuder (8- channel, 60 cm, 16.7 L min^?1 air sampling rate) trapped small amounts of several non-volatile PAH. This result is consistent with particle diffusion losses of 5 to 10% for particles less than 0.05 μm under the flow conditions in the denuder. The 60-cm denuder was probably longer than necessary for the flow rate used. During the sampling, both glass fiber and Teflon-coated glass fiber filters were used. Without a denuder in front of a glass fiber filter, the fine particulate mass (PM 2.5) measurements showed a major positive bias that has been attributed to adsorption of gases by the filter. Teflon-coated glass fiber filters were not subject to this artifact problem, and equal masses were collected on filters from the denuded and non-denuded air flows.     

Methamidophos removal from aqueous solutions using a super adsorbent based on crosslinked poly(vinyl alcohol) hydrogel

This study describes the absorption of methamidophos (MMP) from aqueous solution by crosslinked poly(vinyl alcohol) (PVA) hydrogel synthesized using malic acid (MA) as a crosslinker (CLPHMA). The prepared hydrogels were characterized by FTIR spectroscopy, scanning electron microscopy, and the thermal properties were studied by using thermal gravimetric analysis. Also, the swelling index as a function of PVA:MA composition and pH were studied. An in silico rational study, which involved all‐atom molecular dynamics simulations of PVA:MA systems in proportions 10:2, 10:4, and 10:6 was performed. The in silico studies concluded that the more suitable crosslinking degree for MMP pesticide removal is with the 20% (wt %) of crosslinker (CLPHMA‐20). The experimental analysis of MMP removal with CLPHMA was performed as well. It was found that the prepared CLPHMA‐20 had a great efficiency to recover around 86% of MMP from their solutions. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45964.     

Nootkatone Is a Repellent for Formosan Subterranean Termite (Coptotermes formosanus)

We examined the behavior of Formosan subterranean termites toward one of the components of vetiver grass oil, the roots of which manufacture insect repellents. We found nootkatone, a sesquiterpene ketone, isolated from vetiver oil is a strong repellent and toxicant to Formosan subterranean termites. The lowest effective concentration tested was 10 g/g substrate. This is the first report of nootkatone being a repellent to insects.     

Molecular Basis of Selectivity and Activity for the Antimicrobial Peptide Lynronne-1 Informs Rational Design of Peptide with Improved Activity

Antibiotic resistance is a significant threat to human health, with natural products remaining the best source for new antimicrobial compounds. Antimicrobial peptides (AMPs) are natural products with great potential for clinical use as they are small, amenable to customization, and show broad-spectrum activities. Lynronne-1 is a promising AMP identified in the rumen microbiome that shows broad-spectrum activity against pathogens such as methicillin-resistant Staphylococcus aureus and Acinetobacter baumannii. Here we investigated the structure of Lynronne-1 using solution NMR spectroscopy and identified a 13-residue amphipathic helix containing all six cationic residues. We used biophysical approaches to observe folding, membrane partitioning and membrane lysis selective to the presence of anionic lipids. We translated our understanding of Lynronne-1 structure to design peptides which varied in the size of their hydrophobic helical face. These peptides displayed the predicted continuum of membrane-lysis activities in vitro and in vivo, and yielded a new AMP with 4-fold improved activity against A. baumannii and 32-fold improved activity against S. aureus.     

Enhancement of mechanical properties and chemical durability of Soda-lime silicate glasses treated by DC gas discharges

We report for the first time a study on non-contact thermal poling of soda lime silicate glasses using DC gas discharge. In this work, the formation of a glow discharge is evidenced during the thermal poling treatment (longer than 30 minutes). The hardness and the chemical durability of glasses poled under different conditions (contact or non-contact) and atmospheres (nitrogen or air) are measured and compared to that of un-poled reference glass. The results reveal enhanced mechanical and chemical properties for samples poled under nitrogen as compare to air poled or soda lime silicate glass samples. A structural and chemical analysis of surface of the glass using IR-reflectance measurement and ToF-SIMS is also presented. The formation of a “silica-like” layer on the surface of nitrogen poled glasses is observed, which is likely associated with the enhancement of surface properties. On the other hand, the introduction of protons beneath the surface of glasses poled under air leads to the formation of a hydrated alkaline earth silica layer. Based on the observations a mechanism behind the sustainability of the plasma under DC conditions is proposed.