Uranyl complexes formed with apara-t-butylcalix[4]arene bearing phosphinoyl pendant arms on the lower rim. Solid and solution studies

The current interest in functionalized calixarenes with phosphorylated pendant arms resides in their coordination ability towards f elements and capability towards actinide/rare earth separation. Uranyl cation forms 1:1 and 1:2 (M:L) complexes with atetra-phosphinoylated p-tert-butylcalix[4]arene, B4bL4: UO2(NO3)2(B4bL4)n· xH2O (n = 1, x = 2, 1; n = 2, x = 6, 2). Spectroscopic data point to the inner coordination sphere of 1 containing one monodentate nitrate anion, one water molecule and the four phosphinoylated arms bound to UO22+ while in 2, uranyl is only coordinated to calixarene ligands. In both cases the U(VI) ion is 8-coordinate. Uranyl complexes display enhanced metal-centred luminescence due to energy transfer from the calixarene ligands; the luminescence decays are bi-exponential with associated lifetimes in the ranges 220μs <τs <250μs and 630μs <τL < 640μs, pointing to the presence of two species with differently coordinated calixarene, as substantiated by aXPS study of U(4f5/2,7/2), O(1s) and P(2p) levels on solid state samples. The extraction study of UO22+ cation and trivalent rare-earth (Y, La, Eu) ions from acidic nitrate media by B4bL4 in chloroform shows the uranyl cation being much more extracted than rare earth

Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic

This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic

Caribbean-Wide, Long-Term Study of Seagrass Beds Reveals Local Variations, Shifts in Community Structure and Occasional Collapse

The CARICOMP monitoring network gathered standardized data from 52 seagrass sampling stations at 22 sites (mostly Thalassia testudinum-dominated beds in reef systems) across the Wider Caribbean twice a year over the period 1993 to 2007 (and in some cases up to 2012). Wide variations in community total biomass (285 to >2000 g dry m−2) and annual foliar productivity of the dominant seagrass T. testudinum (2000 g dry m−2) were found among sites. Solar-cycle related intra-annual variations in T. testudinum leaf productivity were detected at latitudes > 16°N. Hurricanes had little to no long-term effects on these well-developed seagrass communities, except for 1 station, where the vegetation was lost by burial below ∼1 m sand. At two sites (5 stations), the seagrass beds collapsed due to excessive grazing by turtles or sea-urchins (the latter in combination with human impact and storms). The low-cost methods of this regional-scale monitoring program were sufficient to detect long-term shifts in the communities, and fifteen (43%) out of 35 long-term monitoring stations (at 17 sites) showed trends in seagrass communities consistent with expected changes under environmental deterioration.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Ciencias del Mar y Limnología (CIMAR

Deviations from general mean leaf productivity (ΔP) of <i>Thalassia testudinum</i> per station during High growth season (May-September at site 1 and 2, March –August at all other sites) and Low growth season (October-April at sites 1 and 2, September-February at all other sites).

<p>See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0090600#pone.0090600.s006" target="_blank">Table S4</a> for significance differences of ΔP. Only stations with at least 10 sampling events were included. Numbers above the X-axis indicate site number, and the minor ticks indicate the different sampling stations at those sites.</p

Significant long-term trends in seagrass attributes and community parameters at CARICOMP monitoring stations across the nine sites that showed changes consistent with deterioration of the environmental conditions.

<p>The broken smoothed lines connect annual average values and serve to illustrate the inter-annual variability in the data. Data from all samples per year (N = 4-9, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0090600#pone.0090600.s005" target="_blank">Table S3</a>) were used to determine the regression lines (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0090600#pone.0090600.s008" target="_blank">Table S6</a>). D. For Site14, the relationship was determined for the more persistent <i>Syringodium filiforme</i>.</p