The application of molybdenum disulfide (MoS2) for water decontamination is expanded toward a novel approach for mercury removal using nanofibrous mats coated with MoS2. A bottom-up synthesis method for growing MoS2 on carbon nanofibers was employed to maximize the nanocomposite decontamination potential while minimizing the release of the nanomaterial to treated water. First, a co-polymer of polyacrylonitrile and polystyrene was electrospun as nanofibrous mats and pretreated to form pristine carbon fibers. Next, three solvothermal methods of controlled in situ MoS2 growth of different morphologies were achieved on the surface of the fibers using three different sets of precursors. Finally, these MoS2-enabled fibers were extensively characterized and evaluated for their mercuric removal efficiency. Two mercury removal mechanisms, including reduction–oxidation reactions and physicochemical adsorption, were elucidated. The two nanocomposites with the fastest (0.436 min–1 mg–1) and highest mercury removal (6258.7 mg g–1) were then further optimized through intercalation with poly­(vinylpyrrolidone), which increased the MoS2 interlayer distance from 0.68 nm to more than 0.90 nm. The final, optimal fabrication technique (evaluated according to mercuric capacity, kinetics, and nanocomposite stability) demonstrated five times higher adsorption than the second-best method and obtained 70% of the theoretical mercury adsorption capacity of MoS2. Overall, results from this study indicate an alternative, advanced material to increase the efficiency of aqueous mercury removal while also providing the basis for other novel environmental applications such as selective sensing, disinfection, and photocatalysis.

Increasing silver nanoparticle (AgNP) use in sprays, consumer products and medical devices has raised concerns about potential health effects. While previous studies have investigated AgNPs, most were limited to a single particle size or surface coating. In this study, we investigated the effect of size, surface coating and dose on the persistence of silver in the lung following exposure to AgNP. Adult male rats were intratracheally instilled with four different AgNPs: 20 or 110nm in size and coated with either citrate or polyvinylpyrrolidone (PVP) at 0.5 or 1.0mg/kg doses. Silver retention was assessed in the lung at 1, 7 and 21 days post exposure. ICP-MS quantification demonstrated that citrate coated AgNPs persisted in the lung to 21 days with greater than 90% retention, while PVP coated AgNP had less than 30% retention. Localization of silver in lung tissue at one day post exposure demonstrated decreased silver in proximal airways exposed to 110nm particles compared with 20nm AgNPs. In terminal bronchioles one day post exposure, silver was localized to surface epithelium but was more prominent in the basement membrane at 7 days. Silver positive macrophages in bronchoalveolar lavage fluid decreased more quickly after exposure to particles coated with PVP. We conclude that PVP coated AgNPs had less retention in the lung tissue over time and larger particles were more rapidly cleared from large airways than smaller particles. The 20nm citrate particles the greatest effect; increasing lung macrophages even 21days after exposure and resulted in the greatest silver retention in lung tissue.

Migraineurs show hypersensitivity to sensory stimuli at various stages throughout the migraine cycle. A number of putative processes have been implicated including a dysfunction in the descending pain modulatory system in which the periaqueductal gray (PAG) is considered to play a crucial role. Recurring migraine attacks could progressively perturb this system, lowering the threshold for future attacks, and contribute to disease chronification. Here, we investigated PAG connectivity with other brain regions during a noxious thermal stimulus to determine changes in migraineurs, and associations with migraine frequency. 21 episodic migraine patients and 22 matched controls were included in the study. During functional MRI, a thermode was placed on the subjects’ temple delivering noxious and non-noxious heat stimuli. A psychophysiological interaction (PPI) analysis was carried out to examine pain-induced connectivity of the PAG with other brain regions. The PPI analysis showed increased PAG connectivity with the S1 face representation area and the supplementary motor area, an area involved with pain expectancy, in patients with higher frequency of migraine attacks. PAG connectivity with regions involved with the descending pain modulatory system (i.e., prefrontal cortex) was decreased in the migraineurs versus healthy individuals. Our results suggest that high frequency migraineurs may have diminished resistance to cephalic pain and a less efficient inhibitory pain modulatory response to external stressor (i.e., noxious heat). The findings support the notion that in migraine there is less effective pain modulation (viz., decreased pain inhibition or increased pain facilitation), potentially contributing to increased occurrence of attacks/chronification of migraine.