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Correction: 10.1021/acs.joc.1c02513. The tear film lipid layer (TFLL) that covers the ocular surface contains several unique lipid classes, including O-acyl-omega-hydroxy fatty acids, type I-St diesters, and type II diesters. While the TFLL represents a unique biological barrier that plays a central role in stabilizing the entire tear film, little is known about the properties and roles of individual lipid species. This is because their isolation from tear samples in sufficient quantities is a tedious task. To provide access to these species in their pure form, and to shed light on their properties, we here report a general strategy for the synthesis and structural characterization of these lipid classes. In addition, we study the organization and behavior of the lipids at the air-tear interface. Through these studies, new insights on the relationship between structural features, such as number of double bonds and the chain length, and film properties, such as spreading and evaporation resistance, were uncovered.

The labile fraction of dissolved organic phosphorus (DOP) – predominantly consisting of phosphoric esters – is an important microbial P source in the subtropical oligotrophic ocean. However, unlike phosphate, knowledge for labile DOP is still limited due to the scarcity of broad and intensive observations. In this study, we examined the concentrations and size-fractionated hydrolysis rates of labile phosphoric monoesters and diesters along a >10,000 km longitudinal transect in the North Pacific (23°N; upper 200-m layer). Depth-integrated monoesters decreased westward with a maximum difference of fivefold. Vertical profiles of monoesters in the eastern and western basins showed decreasing and increasing trends with depth, respectively. The monoester-depleted shallow layer of the western basin was associated with phosphate depletion and monoesterase activity was predominant in the large size fraction (>0.8 μm), suggesting that monoesters are significant P sources particularly for large microbes. In contrast, diester concentrations were generally lower than monoester concentrations and showed no obvious horizontal or vertical variation in the study area. Despite the unclear distribution pattern of diesters, diesterase activity in the particulate fraction (>0.2 μm) increased in the phosphate-depleted shallow layer of the western basin, suggesting that the targeted diesters in the assay were also important microbial P sources. Diesterase activities in the dissolved fraction (

We sampled ammonium sulfate particles and indoor particles of outdoor origin through a small chamber covered with polyvinyl chloride flooring. We measured the uptake of semivolatile organic compounds (SVOCs) by the airborne particles in real time. The particles acquired SVOC mass fractions up to 10%. The phthalate ester (di(2-ethylhexyl)-phthalate) (DEHP), a known endocrine disruptor, contributed by approximately half of the sorbed SVOC mass. The indoor particles acquired a higher DEHP fraction than laboratory-generated ammonium sulfate aerosol. We attribute this increased uptake to absorption by organic matter present in the indoor particles. Using a thermodenuder to remove volatile components, predominantly organics, reduced the SVOC uptake. Positive matrix factorization applied to the organic mass spectra suggests that hydrocarbon-like organic aerosol (typically fresh traffic exhaust) sorbs DEHP more efficiently than aged organic aerosol. The SVOC uptake is one of the processes that modify outdoor pollution particles after they penetrate buildings, where the majority of exposure occurs. Particles from indoor sources, typically dominated by organic matter, will undergo such processes as well. Aerosol mass spectrometry improves the time resolution of experimental investigations into these processes and enables experiments with lower, relevant particle concentrations. Additionally, particle size-resolved results are readily obtained.

International audience; The first non-natural derivative of the rare D-glucose-2-phosphate (G2P), namely glucose-2-(O-lactic acid phosphate) (G2LP), has been synthesized. When used as sole carbon source, G2LP enables bacterial growth of the plant pathogenic strain Agrobacterium fabrum C58 (formerly referred to as Agrobacterium tumefa-ciens). X-ray crystallography and affinity measurements investigations reveal that G2LP binds the periplasmic binding protein (PBP) AccA similarly to the natural compounds and with the same affinity. Moreover, enzy-matic assays show that it is able to serve as substrate of the phosphodiesterase AccF. The properties found for G2LP demonstrate that the very unusual glucose-2-phosphoryl residue, present in G2LP, can be used as structural feature for designing non-natural systems fully compatible with the Acc cascade of A. fabrum.

The use of natural resources as a chemical feedstock for the synthesis of added-value products is gaining interest; as such we report an environmentally friendly method for the synthesis of para-menthane-3,8-diol from natural citronellal oil in 96% yield, under solvent free aqueous conditions. The acylation of para-menthane-3,8-diol with various acid anhydrides over polymer-supported scandium triflate (PS-Sc(OTf)3) catalyst was subsequently developed, where both hydroxy groups of para-menthane-3,8-diol could be simultaneous acylated under mild reaction conditions to form the corresponding diesters in good yields. The advantages of this method include a simple procedure from natural resources, using solvent-free reaction conditions.