Activity

0001] and PM10 [slope = 0.46 (±0.09); p-value less then 0.0001] samples. Measurements at the Harvard Supersite and at EPA RadNet sites are highly correlated for both α-activities [slope = 0.17 (±0.02), p-value less then 0.0001] and β-activities [slope = 0.30 (±0.05), p-value less then 0.0001]. Additionally, we identified several significant predictors for PM2.5 α-activities. This novel method we developed to measure α- and β-activities from archived filters will make it possible to assess the retrospective particle radioactivity exposure for future epidemiological studies.Prenatal hydroxylated polychlorinated biphenyls (OH-PCBs) exposure may disrupt fetal brain development during the critical period of thyroid hormone (TH) action. However, there are limited studies on the OH-PCB transfer to the fetal brain, particularly in primates. In this study, we selected the Japanese macaque (Macaca fuscata) as a model animal for the fetal transfer of OH-PCBs in humans and revealed OH-PCB concentrations and their relationships in maternal and fetal blood, liver, and brain. l-thyroxine (T4)-like OH-PCBs including 4OH-CB187, a major congener in humans, were found in high proportions in the blood, liver, brain, and placenta of pregnant Japanese macaques. OH-PCBs were detected in the fetal brain and liver in the first trimester, indicating their transfer to the brain in the early pregnancy stage. 4OH-CB187 and 4OH-CB202 were the major congeners found in fetal brain, indicating that these T4-like OH-PCBs are transported from maternal blood to the fetal brain via the placenta. These results indicate that further studies are needed on the effects of OH-PCBs on the developing fetal brain.Interlayered thin-film nanocomposite membranes (TFNi) are an emerging type of membranes with great potential to overcome the permeability-selectivity upper bound of conventional thin-film composite (TFC) nanofiltration and reverse osmosis membranes. However, the exact roles of the interlayer and the corresponding mechanisms leading to enhanced separation performance of TFNi membranes remain poorly understood. This study reports a polydopamine (PDA)-intercalated TFNi nanofiltration membrane (PA-PSF2, PDA coating time of 2 h) that possessed nearly an order of magnitude higher water permeance (14.8 ± 0.4 Lm-2 h-1 bar-1) than the control TFC membrane (PA-PFS0, 2.4 ± 0.5 Lm-2 h-1 bar-1). The TFNi membrane further showed enhanced rejection toward a wide range of inorganic salts and small organic molecules (including antibiotics and endocrine disruptors). Detailed mechanistic investigation reveals that the membrane separation performance was enhanced due to both the direct “gutter” effect of the PDA interlayer and its indirect effects resulting from enhanced polyamide formation on the PDA-coated substrate, with the “gutter” effect playing a more dominant role. This study provides a mechanistic and comprehensive framework for the future development of TFNi membranes.Per and polyfluoroalkyl substances (PFAS), legacy chemicals used in firefighting and the manufacturing of many industrial and consumer goods, are widely found in groundwater resources, along with other regulated compounds, such as chlorinated solvents. Due to their strong C-F bonds, these molecules are extremely recalcitrant, requiring advanced treatment methods for effective remediation, with hydrated electrons shown to be able to defluorinated these compounds. A combined photo/electrochemical method has been demonstrated to dramatically increase defluorination rates, where PFAS molecules sorbed onto appropriately functionalized cathodes charged to low cell potentials (-0.58 V vs Ag/AgCl) undergo a transient electron transfer event from the electrode, which “primes” the molecule by reducing the C-F bond strength and enables the bond’s dissociation upon the absorption of a hydrated electron. In this work, we explore the impact of headgroup and chain length on the performance of this two-electron process and extend this technique to chlorinated solvents. G Protein agonist We use isotopically labeled PFAS molecules to take advantage of the kinetic isotope effect and demonstrate that indeed PFAS defluorination is likely driven by a two-electron process. We also present density functional theory calculations to illustrate that the externally applied potential resulted in an increased rate of electron transfer, which ultimately increased the measured defluorination rate.Expanded polystyrene (EPS) is a common plastic marine debris found in oceans worldwide. The unique “foamed” structure of EPS, which is composed of thin layers, is more vulnerable to fragmentation than bulk plastics. However, the production rate of micro- and nanoplastics by the fragmentation of EPS following sunlight exposure remains largely unknown. Here, we determined the fragmentation rate and weight loss of EPS in an outdoor weathering experiment that ran for 24 months. It took only 1 month for the weight of an EPS box to decline by 5% due to photodegradation, and approximately 6.7 × 107 micro- and nanoparticles/cm2 could be produced at a latitude of 34 °N. These results indicate that macro EPS debris can continually produce a massive number of particles within a relatively short exposure duration. The findings provide useful information to inform policymakers how rapidly to remove “likely fragmented” plastic litter from the environment.Graphene oxide derivatives (GODs) have superb physical/chemical properties with promise for applications in biomedicine. Shape, size, and chemistry of the GODs are identified as the key parameters that impact any biological system. In this work, the GODs with a wide range of shapes (sheets, helical/longitudinal ribbons, caps, dots), sizes (10 nm to 20 μm), and chemistry (partially to fully oxidized) are synthesized, and their cytotoxicity in normal cells (NIH3T3) and colon cancer cells (HCT116) are evaluated. The mechanisms by which the GODs induce cytotoxicity are comprehensively investigated, and the toxic effects of the GODs on the NIH3T3 and the HCT116 cells are compared. While the GODs show no toxicity under the size of 50 nm, they impose moderate toxic effects at the sizes of 100 nm to 20 μm (max viability >57%). For the GODs with the similar size (100-200 nm), the helical ribbon-like structure is found to be much less toxic than the longitudinal ribbon structure (max viability 83% vs 18%) and the tubular structure (0% viability for the oxidized carbon nanotubes).