Force Base containing some of the largest tracts. Feral swine damage is one of the greatest threats to this wetland habitat. We conducted a multi-year study to evaluate the impacts of sport hunting and supplemental swine removal on damage to seepage slopes. Prior to initiation of removal in 2003, swine damage to seepage slopes in the portion of the base closed to hunting averaged 25.0%, over twice the 10.9% losses in the portion open to hunting. After less than one year of supplemental removal, damage in the closed-to-hunting area dropped to 7.2%. Although supplemental removal was not applied in the open hunting area, damage dropped significantly to 5.6%, statistically indistinguishable from the swine-controlled (closed) portion. After another year of removal, average damage in the closed hunting area dropped further to 5.6%, while the open hunting area dropped to 4.3%, again statistically indistinguishable. Even though removal was only applied to the area closed to hunting, it also produced damage reductions in the open hunting area, as swine were free to move among areas. Declines in damage following implementation of removal corresponded with large drops in swine population indices for the base. Economic valuations of seepage slope damage losses demonstrated substantial benefit-cost ratios for application of removal.

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We report the first comprehensive study on the purification of PbS quantum dots (QDs) using gel permeation chromatography (GPC). GPC enables the efficient and repeatable separation of unbound small molecules from QDs in a homogeneous solvent environment. This separation allows us to gain further insight into the surface capping layer of PbS QDs and measure the ligand density on QDs of different sizes. We find that small oleate-capped PbS QDs are stable in solution in toluene after purification by GPC with negligible free ligand concentrations. However, purification of larger-diameter QDs reveals two oleate populations that persist after multiple GPC purifications: one with a broad olefin resonance characteristic of strongly bound ligands in smaller QDs, and the other with a narrower peak suggesting dynamic exchange with freely diffusing species. Variable-temperature NMR indicates a reversible equilibrium between the two populations, which is also observed in samples purified through precipitation with a polar solvent. The observation of two oleate populations following GPC purification is maintained even when the large-diameter QDs are formed using a strictly anhydrous procedure that should eliminate the presence of water, hydroxide, or oleic acid in as-synthesized samples. In conducting this strictly anhydrous synthesis, we incidentally observe that water plays a role in determining the resultant size of PbS QDs prepared by traditional methods compared to their anhydrous analogues. Understanding how the surfaces of PbS QDs are terminated should aid in interpreting their behavior in subsequent ligand exchange steps as necessary for diverse applications.

Predation critically threatens reproductive success of sea turtles and shorebirds at many of Florida's beaches. We examined the biological and bioeconomic results of predator management on two adjacent barrier islands, Cayo Costa and North Captiva, along Florida's west coast. Both islands suffered severe nesting losses due to predation and disturbance due to raccoons, while Cayo Costa also was impacted by a large population of feral swine. In 2006, our initial year of study, neither island received predator management and no least tern production occurred on either island, and sea turtle nest predation was 74% and 60%, respectively, for Cayo Costa and North Captiva. Predators were managed in 2007 on Cayo Costa while North Captiva served as an untreated reference island. North Captiva again had no least tern production and sea turtle nest predation was 84%. In contrast, Cayo Costa produced 31 least terns and sea turtle nest predation plummeted to 16%. Both islands received predator management in 2008 when Cayo Costa and North Captiva respectively produced 20 and 55 least terns and had 15% and 0% sea turtle nest predation. The entire costs for predator management by experts over the course of the study was $USD 39,636, while the returns in additional production of least tern young and hatchling sea turtles was valued over $USD 1.1 million for a resulting benefit-cost ratio of 27.8.Published by Elsevier B.V.

This study addresses the colloidal stability of polymer-coated core/shell CdSe/Cd x Zn 1−x S quantum dots (QDs) in the presence of L-glutathione (GSH) under neutral conditions by means of photoluminescence (PL) and absorption spectroscopy. A reversible addition−fragmentation chain-transfer-mediated synthesis was employed to produce co-polymer ligands with different molecular weights in block and random sequences. Poly(ethylene glycol) sidechains were incorporated on a methacrylate backbone for solubility in phosphate-buffered saline. Imidazole-bearing histamine sidechains were installed postsynthetically to facilitate binding to the QD surface. Introduction of L-glutathione, an endogenous monothiol, to aqueous solutions of the polymer-coated QDs led to an increase in PL quantum yield, indicating an interaction between the QD and glutathione. The PL change was greatly diminished for block co-polymers versus random co-polymers of similar molecular weight and composition. Additionally, higher ligand populations were found upon initial purification of block co-polymer-coated QDs versus the random co-polymers. We demonstrate that glutathione does not significantly displace the polymer ligands from the QD surface, suggesting that PL changes are driven primarily through ligand association. The block copolymers are more resistant to glutathione association, and indeed stronger binders, than the randomly ordered co-polymers, with higher-molecular-weight contributing to improved stability in both cases. To the best of our knowledge, this is the first study to directly compare the relative stability of block and random polymeric imidazole ligands and should aid in developing more stable ligand-exchanged QDs for bioimaging and biosensing, especially for in vivo and intracellular applications.

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