More Like this

1. Using δ¹⁸O and δ²H to Detect Hydraulic Connection Between a Sinkhole Lake and a First‐Magnitude Spring

   https://doi.org/10.1111/gwat.13105  

   Ahmed, Nur; Ye, Ming; Wang, Yang; Greenhalgh, Tom; Fowler, Karlee (April 2021, Groundwater)

   null (Ed.)

   Oxygen and hydrogen isotopes were used in this study to detect a hydraulic connection between a sinkhole lake and a karst spring. In karst areas, surface water that flows to a lake can drain through sinkholes in the lakebed to the underlying aquifer, and then flows in karst conduits and through aquifer matrix. At the study site located in northwest Florida, USA, Lake Miccosukee immediately drains into two sinkholes. Results from a dye tracing experiment indicates that lake water discharges at Natural Bridge Spring, a first-magnitude spring 32 km downgradient from the lake. By collecting weekly water samples from the lake, the spring, and a groundwater well 10 m away from the lake during the dry period between October 2019 and January 2020, it was found that, when rainfall effects on isotopic signature in spring water are removed, increased isotope ratios of spring water can be explained by mixing of heavy-isotope-enriched lake water into groundwater, indicating hydraulic connection between the lake and the spring. Such a detection of hydraulic connection at the scale of tens of kilometers and for a first-magnitude spring has not been previously reported in the literature. Based on the isotope ratio data, it was estimated that, during the study period, about 8.5% the spring discharge was the lake water that drained into the lake sinkholes. 

   more » « less
2. Phosphatidylinositol 3, 5‐bisphosphate regulates Ca ²⁺ transport during yeast vacuolar fusion through the Ca ²⁺ ATPase Pmc1

   https://doi.org/10.1111/tra.12736  

   Miner, Gregory E.; Sullivan, Katherine D.; Zhang, Chi; Rivera‐Kohr, David; Guo, Annie; Hurst, Logan R.; Ellis, Ez C.; Starr, Matthew L.; Jones, Brandon C.; Fratti, Rutilio A. (July 2020, Traffic)

   null (Ed.)
3. Computational protocol for predicting ¹⁹F NMR chemical shifts for PFAS and connection to PFAS structure

   https://doi.org/10.1002/jcc.26939  

   Mifkovic, Maleigh; Pauling, Jessica; Vyas, Shubham (July 2022, Journal of Computational Chemistry)
4. Formation of monomeric Sn( ii ) and Sn( iv ) perfluoropinacolate complexes and their characterization by ¹¹⁹ Sn Mössbauer and ¹¹⁹ Sn NMR spectroscopies

   https://doi.org/10.1039/d0dt02837a  

   Elinburg, Jessica K.; Hyre, Ariel S.; McNeely, James; Alam, Todd M.; Klenner, Steffen; Pöttgen, Rainer; Rheingold, Arnold L.; Doerrer, Linda H. (October 2020, Dalton Transactions)

   null (Ed.)

   The synthesis and characterization of a series of Sn( ii ) and Sn( iv ) complexes supported by the highly electron-withdrawing dianionic perfluoropinacolate (pin F ) ligand are reported herein. Three analogs of [Sn IV (pin F ) 3 ] 2− with NEt 3 H + ( 1 ), K + ( 2 ), and {K(18C6)} + ( 3 ) counter cations and two analogs of [Sn II (pin F ) 2 ] 2− with K + ( 4 ) and {K(15C5) 2 } + ( 5 ) counter cations were prepared and characterized by standard analytical methods, single-crystal X-ray diffraction, and 119 Sn Mössbauer and NMR spectroscopies. The six-coordinate Sn IV (pin F ) complexes display 119 Sn NMR resonances and 119 Sn Mössbauer spectra similar to SnO 2 (cassiterite). In contrast, the four-coordinate Sn II (pin F ) complexes, featuring a stereochemically-active lone pair, possess low 119 Sn NMR chemical shifts and relatively high quadrupolar splitting. Furthermore, the Sn( ii ) complexes are unreactive towards both Lewis bases (pyridine, NEt 3 ) and acids (BX 3 , Et 3 NH + ). Calculations confirm that the Sn( ii ) lone pair is localized within the 5s orbital and reveal that the Sn 5p x LUMO is energetically inaccessible, which effectively abates reactivity. 

   more » « less
5. Total Synthesis of UCS1025A via Tandem Carbonylative Stille Cross Coupling and Diels‐Alder Reaction ^†

   https://doi.org/10.1002/cjoc.202300331  

   Cui, Chengsen; Dai, Mingji (November 2023, Chinese Journal of Chemistry)

   Comprehensive Summary We report an efficient and convergent strategy for the total synthesis of UCS1025A and its diastereomer tetra‐epi‐UCS1025A. UCS1025A is a representative member of the naturally occurring pyrrolizidinone polyketides, from which members with potent antibacterial, antifungal, and anticancer activities have been identified. Our approach features a tandem carbonylative Stille cross coupling and Diels‐Alder reaction to forge a key C—C bond and build thetrans‐decalin system. This tandem process utilizes carbon monoxide as a one‐carbon linchpin to stitch a vinyl triflate and a vinylstannane together and form the desired enone moiety for the subsequent intramolecular Diels‐Alder cyclization. Our synthesis also provides a versatile approach for the synthesis of other related pyrrolizidinone‐containing polyketides. 

   more » « less