Search

A sulfate polysaccharide fraction (PYSP) was extracted and purified through DEAE cellucose-52 and Sephadex G-100 from Porphyra yezoensis. The PYSP is an acidic polysaccharide with a Mw of 152.93 kDa. PYSP was composed of galactose, glucose, and Glc-UA sugars with a molar ratio of 82.38:5.02:12.59. PYSP has an irregular fragmentation structure, with a sulfuric acid group content of 43.93% ± 0.47%. It suggested that PYSP has effective cholate and cholesterol adsorption capacity, α-glucosidase inhibition activity. When the concentration of PYSP was 1.0 mg/mL, the inhibition rates of α-glucosidase were 45.02%. PYSP could decrease α-helix and increase β-fold and random curl of α-glucosidase. In addition, the in vitrohypoglycemic activities of PYSP were dose-dependent. PYSP could improve glucose consumption, glycogen synthesis, and pyruvate kinase activity in insulin-resistant HepG2 cells. These results suggested that PYSP is a novel material for functional hypoglycemic foods.

Water supplies for millions of U.S. individuals exceed maximum contaminant levels for per- and polyfluoroalkyl substances (PFAS). Contemporary and legacy use of aqueous film forming foams (AFFF) is a major contamination source. However, diverse PFAS sources are present within watersheds, making it difficult to isolate their predominant origins. Here we examine PFAS source signatures among six adjacent coastal watersheds on Cape Cod, MA, U.S.A. using multivariate clustering techniques. A distinct signature of AFFF contamination enriched in precursors with six perfluorinated carbons (C6) was identified in watersheds with an AFFF source, while others were enriched in C4 precursors. Principal component analysis of PFAS composition in impacted watersheds showed a decline in precursor composition relative to AFFF stocks and a corresponding increase in terminal perfluoroalkyl sulfonates with < C6 but not those with ≥ C6. Prior work shows that in AFFF stocks, all extractable organofluorine (EOF) can be explained by targeted PFAS and precursors inferred using Bayesian inference on the total oxidizable precursor assay. Using the same techniques for the first time in impacted watersheds, we find that only 24%–63% of the EOF can be explained by targeted PFAS and oxidizable precursors. Our work thus indicates the presence of large non-AFFF organofluorine sources in these coastal watersheds.

Rapid declines in legacy poly- and perfluoroalkyl substances (PFASs) have been reported in human populations globally following changes in production since 2000. However, changes in exposure sources are not well understood. Here, we report serum concentrations of 19 PFASs (?19PFAS) measured in children between 1993 and 2012 from a North Atlantic fishing community (Faroe Islands). Median ?19PFAS concentrations in children (ages 5–13 years) peaked in 2000 (47.7 ng mL–1) and declined significantly by 14.4% year–1until 2012. Principal component analysis (PCA) identified two groups of PFASs that likely reflect exposures from diverse consumer products and a third group that consisted of perfluorocarboxylic acids (PFCAs) with nine or more carbons (C = 9). These C = 9 PFASs are strongly associated with mercury in children’s hair, a well-established proxy for seafood consumption, especially perfluoroundecanoic acid (PFUnDA, r= 0.72). Toxicokinetic modeling shows PFAS exposures from seafood have become increasingly important (53% of perfluorooctanesulfonate, PFOS, in 2012), despite a decline in whale consumption in recent years. We infer that even in a major seafood-consuming population, declines in legacy PFAS exposure after 2000 were achieved by the rapid phase out of PFOS and its precursors in consumer products. These results emphasize the importance of better understanding exposures to replacement PFASs in these sources.

We propose an overlapping algorithm utilizing the K -means clustering technique to group scattered data nodes for discretizing elliptic partial differential equations. Unlike conventional kernel-based approximation methods, which select the closest points from the entire region for each center, our algorithm selects only the nearest points within each overlapping cluster. We present computational results to demonstrate the efficiency of our algorithm for both two-dimensional and three-dimensional problems. For evaluation and validation, these results are compared with results obtained using the RBF-FD+polynomial method with different kernels. [ABSTRACT FROM AUTHOR]