All-inorganic CsPbI3 perovskite quantum dots (QDs) have
attracted intense attention for their successful application in photovoltaics
(PVs) and optoelectronics that are enabled by their superior absorption
capability and great photoluminescence (PL) properties. However, their
photostability remains a practical bottleneck and further optimization
is highly desirable. Here, we studied the photostability of as-obtained
colloidal CsPbI3 QDs suspended in hexane. We found that
light illumination does induce photodegradation of CsPbI3 QDs. Steady-state spectroscopy, X-ray diffraction, Fourier transform
infrared spectroscopy, transmission electron microscopy, and transient
absorption spectroscopy verified that light illumination leads to
detachment of the capping agent, collapse of the CsPbI3 QD surface, and finally aggregation of surface Pb0. Both
dangling bonds containing surface and Pb0 serve as trap
states causing PL quenching with a dramatic decrease of PL quantum
yield. Our work provides a detailed insight about the correlation
between the structural and photophysical consequences of the photodegradation
process in CsPbI3 QDs and may lead to the optimization
of such QDs toward device applications.
Enantioselective trifluoromethylthiolation, especially of alkenes, is a challenging task. In this work, we have developed an efficient approach for enantioselective trifluoromethylthiolating lactonization by designing an indane-based bifunctional chiral sulfide catalyst and a shelf-stable electrophilic SCF3 reagent. The desired products were formed with diastereoselectivities of >99:1 and good to excellent enantioselectivities. The transformation represents the first enantioselective trifluoromethylthiolation of alkenes and the first enantioselective trifluoromethylthiolation that is enabled by a catalyst with a Lewis basic sulfur center.
Natural products have always been important resources either as therapeutic agents or as lead compounds for the production of pharmaceutical compounds. Osthole, 7-methoxy-8-(3-methyl-2-butenyl) coumarin, an ingredient of a Traditional Chinese Medicine(TCM), has received considerable attention recently because of its significant and diverse pharmacological activities, including anticancer, antisteoporotic, and antiproliferative, which make it a very promising natural lead compound for new drug discovery. The present work summarizes the related biological information on osthole and its analogues and proposes the possibility of its development as a promising lead compound for drug discovery.
The IceCube Neutrino Observatory at the South Pole has measured the diffuse astrophysical neutrino flux up to ∼PeV energies and is starting to identify first point source candidates. The next generation facility, IceCube-Gen2, aims at extending the accessible energy range to EeV in order to measure the continuation of the astrophysical spectrum, to identify neutrino sources, and to search for a cosmogenic neutrino flux. As part of IceCube-Gen2, a radio array is foreseen that is sensitive to detect Askaryan emission of neutrinos beyond ∼30 PeV. Surface and deep antenna stations have different benefits in terms of effective area, resolution, and the capability to reject backgrounds from cosmic-ray air showers and may be combined to reach the best sensitivity. The optimal detector configuration is still to be identified. This contribution presents the full-array simulation efforts for a combination of deep and surface antennas, and compares different design options with respect to their sensitivity to fulfill the science goals of IceCube-Gen2.
We constrain interacting dark matter and dark energy (IDMDE) models using a 450-degreesquare cosmic shear data from the Kilo Degree Survey (KiDS) and the angular power spectra from Planck's latest cosmic microwave background measurements. We revisit the discordance problem in the standard Lambda cold dark matter (ΛCDM) model between weak lensing and Planck datasets and extend the discussion by introducing interacting dark sectors. The IDMDE models are found to be able to alleviate the discordance between KiDS and Planck as previously inferred from the ΛCDM model, and moderately favored by a combination of the two datasets.
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