76 research outputs found
VIVO and VIV Species Formed in Aqueous Solution by the Tridentate GlutaroimideâDioxime Ligand â An Instrumental and Computational Characterization
Complexation of VIV in aqueous solution with glutaroimideâdioxime (H3L), a ligand proposed for the possible sequestration of uranium from seawater, was studied by the combined application of spectroscopic (EPR and UV/Vis), spectrometric (ESIâMS), electrochemical (CV), and computational (DFT) techniques. The results indicate that a rare nonâoxido VIV species, with formula [VIVL2]2â, is formed in the pH range 3â5. It transforms into a usual VIVO complex, [VIVOL(OH)]2â, at pH > 6. The nonâoxido species is characterized by a "type 3" EPR spectrum with Az â 126 Ă 10â4 cmâ1 and a UV/Vis signal with Δ > 2000 mâ1âcmâ1 in the visible region. The detection of VV species by ESIâMS spectrometry was related to two possible oxidation processes, the first one in solution and the second one inâsource during the recording of the spectra. The cyclic voltammogram of [VIVL2]2â shows two quasiâreversible processes, at E1/2 = â0.75 V and E1/2 = 0.03 V, assigned to the VIV/VIII reduction and VIV/VV oxidation, respectively. All the experimental results were verified by DFT calculations, which indicated that the geometry of the nonâoxido VIV complex is intermediate between an octahedron and a trigonal prism and allowed us to predict its 51V hyperfine coupling (HFC) tensor A, the electron absorption spectrum, the two redox processes in the cyclic voltammogram, and the electronic structure that, in turn, determines its EPR and UV/Vis behavior
Using rapid indicators for Enterococcus to assess the risk of illness after exposure to urban runoff contaminated marine water
Background: Traditional fecal indicator bacteria (FIB) measurement is too slow (>18 h) for timely swimmer warnings. Objectives: Assess relationship of rapid indicator methods (qPCR) to illness at a marine beach impacted by urban runoff. Methods: We measured baseline and two-week health in 9525 individuals visiting Doheny Beach 2007-08. Illness rates were compared (swimmers vs. non-swimmers). FIB measured by traditional (Enterococcus spp. by EPA Method 1600 or Enterolertâą, fecal coliforms, total coliforms) and three rapid qPCR assays for Enterococcus spp. (Taqman, Scorpion-1, Scorpion-2) were compared to health. Primary bacterial source was a creek flowing untreated into ocean; the creek did not reach the ocean when a sand berm formed. This provided a natural experiment for examining FIB-health relationships under varying conditions. Results: We observed significant increases in diarrhea (OR 1.90, 95% CI 1.29-2.80 for swallowing water) and other outcomes in swimmers compared to non-swimmers. Exposure (body immersion, head immersion, swallowed water) was associated with increasing risk of gastrointestinal illness (GI). Daily GI incidence patterns were different: swimmers (2-day peak) and non-swimmers (no peak). With berm-open, we observed associations between GI and traditional and rapid methods for Enterococcus; fewer associations occurred when berm status was not considered. Conclusions: We found increased risk of GI at this urban runoff beach. When FIB source flowed freely (berm-open), several traditional and rapid indicators were related to illness. When FIB source was weak (berm-closed) fewer illness associations were seen. These different relationships under different conditions at a single beach demonstrate the difficulties using these indicators to predict health risk
Optimal multilevel methods for H(grad), H(curl), and H(div) systems on graded and unstructured grids
New insights into the genetic etiology of Alzheimer's disease and related dementias
Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE Δ4 allele
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