Sherman Dougherty (climbpastor5)
These results yield fundamental insights into the mechanism by which mobile ions are inserted along extended defects and provide a strategy to overcome a limitation to switching speed in electrochemical devices that exploit ion insertion.Pancreatic β cells are responsible for insulin secretion and are important for glucose regulation in a healthy body and diabetic disease patient without prelabeling of islets. While the conventional biomarkers for diabetes have been glucose and insulin concentrations in the blood, the direct determination of the pancreatic β cell mass would provide critical information for the disease status and progression. By combining fluorination and diversity-oriented fluorescence library strategy, we have developed a multimodal pancreatic β cell probe PiF for both fluorescence and for PET (positron emission tomography). By simple tail vein injection, PiF stains pancreatic β cells specifically and allows intraoperative fluorescent imaging of pancreatic islets. PiF-injected pancreatic tissue even facilitated an antibody-free islet analysis within 2 h, dramatically accelerating the day-long histological procedure without any fixing and dehydration step. Not only islets in the pancreas but also the low background of PiF in the liver allowed us to monitor the intraportal transplanted islets, which is the first in vivo visualization of transplanted human islets without a prelabeling of the islets. Finally, we could replace the built-in fluorine atom in PiF with radioactive 18F and successfully demonstrate in situ PET imaging for pancreatic islets.A donor-π-acceptor strategy is being well exploited in several fields in view of their robust optical properties. However, the impact of branching in quadrupolar [A-(π-D)2] and octupolar [A-(π-D)3] molecules in comparison to parent dipolar (A-π-D) molecules on the delayed fluorescence and phosphorescence properties is seldom explored. We have presented herein the distinct and contrasting optical properties of a tridurylborane core bearing -NH2 (1-3) and -NMe2 (4-6) donor moieties, wherein the number of donors is increased systematically. Because of propeller molecular architecture, the donor and acceptor are weakly coupled, and the frontier molecular orbitals are spatially localized. All of the compounds show delayed fluorescence under ambient conditions and persistent phosphorescence at low temperature. Solvent-dependent studies and temperature-dependent luminescence measurements established that quadrupolar (2 and 5) and octupolar (3 and 6) compounds underwent symmetry breaking in the excited state. Curiously, delayed fluorescence and phosphorescence spectra are found to be blue-shifted and follow the same trend as the fluorescence upon an increase in the branches. The highest quantum yield was observed for dipolar compounds. Besides, the phosphorescence lifetime decreases with an increase in the number of branches. These interesting experimental observations are further supported by quantum-mechanical calculations.Thermoelectric power generation is a reliable energy harvesting technique for directly converting heat into electricity. Recent studies have reported the thermal-to-electrical energy conversion efficiency of thermoelectric generators (TEGs) up to 11% under laboratory settings. However, the practical efficiency of TEGs deployed under real environments is still not more than a few percent. In this study, we provide fundamental insight on the operation of TEGs in realistic environments by illustrating the combinatory effect of thermoelectric material properties, device boundary conditions, and environmental thermal resistivity on TEG performance in conjunction with the module parameters. Using numerical and experimental studies, we demonstrate the existence of a critical heat transfer coefficient that dramatically affects the design and performance of TEGs. Results provide a set of concrete design criteria for developing efficient TEGs that meet the m
