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We report an organic emitter containing a β-triketone electron acceptor core and phenoxazine as the electron donors (TPXZBM) for solution-processed organic light-emitting diodes (OLEDs). The resulting molecule is very unusual because it shows both thermally activated delayed fluorescence and intramolecular proton transfer. We compare its performance with the previously reported diketone analogue PXZPDO. Solution-processed OLEDs of PXZPDO and TPXZBM show maximum external quantum efficiencies of 20.1 and 12.7%, respectively. The results obtained for the solution-processed PXZPDO-based device are as good as the previously reported evaporated device. At a very high luminance of 10,000 cd m-2, the efficiencies of the OLEDs were 10.6% for PXZPDO and 4.7% for TPXZBM, demonstrating a relatively low efficiency roll-off for TADF materials. The low efficiency roll-off was rationalized on the basis of the short delayed lifetimes of 1.35 μs for PXZPDO and 1.44 μs for TPXZBM. Our results suggest that intramolecular proton transfer may be useful for the design of OLED materials with a low efficiency roll-off.Understanding how the sources of an atmospheric organic aerosol (OA) govern its burden is crucial for assessing its impact on the environment and adopting proper control strategies. In this study, the sources of OA over Beijing were assessed year-around based on the combination of two separation approaches for OA, one from chemical fractionation into the high-polarity fraction of water-soluble organic matter (HP-WSOM), humic-like substances (HULIS), and water-insoluble organic matter (WISOM), and the other from statistical grouping using positive matrix factorization (PMF) of high-resolution aerosol mass spectra. Among the three OA fractions, HP-WSOM has the highest O/C ratio (1.36), followed by HULIS (0.56) and WISOM (0.17). PF-562271 The major sources of different OA fractions were distinct HP-WSOM was dominated by more oxidized oxygenated OA (96%); HULIS by cooking-like OA (40%), less oxidized oxygenated OA (27%), and biomass burning OA (21%); and WISOM by fossil fuel OA (77%). In addition, our results provide evidence that mass spectral-based PMF factors are associated with specific substructures in molecules. These structures are further discussed in the context of the FT-IR results. This study presents an overall relationship of OA groups monitored by chemical and statistical approaches for the first time, providing insights for future source apportionment studies.Triboelectric generators are excellent candidates for smart textiles applications due to their ability to convert mechanical energy into electrical energy. Such devices can be manufactured into yarns by coating a conductive core with a triboelectric material, but current triboelectric yarns lack the durability and washing resistance required for textile-based applications. In this work, we develop a unique triboelectric yarn comprising a conducting carbon nanotube (CNT) yarn electrode coated with poly(vinylidene fluoride) (PVDF) fibers deposited by a customized electrospinning process. We show that the electrospun PVDF fibers adhere extremely well to the CNT core, producing a uniform and stable triboelectric coating. The PVDF-CNT coaxial yarn exhibits remarkable triboelectric energy harvesting during fatigue testing with a 33% power output improvement and a peak power density of 20.7 μW cm-2 after 200 000 fatigue cycles. This is potentially due to an increase in the active surface area of the PVDF fiber coating upon repeated contact. Furthermore, our triboelectric yarn meets standard textile industry benchmarks for both abrasion and washing by retaining functionality over 1200 rubbing cycles and 10 washing cycles. We demonstrate the energy harvesting and motion sensing capabilities of our triboelectric yarn in prototype textile-based applications, thereby highlighting its applicability to smart textiles.Surface passivation has demonstrated to be an effective strategy to improve the power conversion efficiency (PCE) and long-term stability of perovskite solar cells (PSCs). Passivation treatment can effectively reduce the density of defect states at the surface and grain boundaries of perovskite films. Herein, a passivation agent of 2-amino-5-(trifluoromethyl)pyridine (5-TFMAP) with bidentate groups is applied to passivate perovskite CH3NH3PbI3 films for the first time. Two types of electron-rich nitrogen atoms from both the pyridine ring and the amino group provide strong interaction with the under-coordinated Pb2+. Additionally, the trifluoromethyl group offers a hydrophobic property and improves moisture stability of the as-fabricated PSCs. It is found that the 5-TFMAP passivation layer can effectively reduce the defect states, promote better carrier transport, and suppress non-radiation recombination of the perovskite films. The best PCE of carbon-based PSCs passivated by the 5-TFMAP agent achieves a high efficiency of 14.96% compared with that of 11.90% for the control PSCs. Moreover, the long-term stability of PSCs with the 5-TFMAP passivation treatment is greatly improved, and its PCE can maintain 80% of its original PCE after being stored for 1200 h with a relative humidity of around 35% at room temperature.Nucleic acid medicine is expected to be among the most promising next-generation therapies. Applications of nucleic acid in vivo are still challenging as a result of the difficulties in direct cell penetration without external assistance. To facilitate the cellular delivery of therapeutic nucleic acid, we developed cell-penetrating aptamers using cell-internalization Systematic Evolution of Ligands by EXponential enrichment (SELEX). Moreover, C20-4 min, a G-quadruplex-forming DNA aptamer, was discovered, showing a higher cell-penetrating capacity compared with other candidates, including AS1411. To verify the formation and understand the G-quadruplex folding topologies of enriched aptamer motifs, characteristic circular dichroism (CD) spectral features are analyzed. The CD spectra of C20-4 min strongly support the formation of parallel G-quadruplexes. Systematic analyses of the G-quadruplex regulation pathway have been performed by combining aptamer pull-down with mass spectrometry. We profiled G-quadruplex aptamers interacting with cellular proteins during internalization and identified helicases and GTPase proteins as cellular interacting partners. In addition, whole transcriptome analysis was performed to study the effects of G-quadruplex aptamers, revealing differentially expressed genes involved in the regulation of GTPase functions. Integrative analyses of transcriptome and proteomic have aided in understanding the functional hierarchy of molecular players in G-quadruplex nucleic acid mechanisms of internalization, which might facilitate developing a novel delivery system.Here we describe the discovery of a new class of C-H borylation catalysts and their use for regioselective C-H borylation of aromatic, heteroaromatic, and aliphatic systems. The new catalysts have Ir-C(thienyl) or Ir-C(furyl) anionic ligands instead of the diamine-type neutral chelating ligands used in the standard C-H borylation conditions. It is reported that the employment of these newly discovered catalysts show excellent reactivity and ortho-selectivity for diverse classes of aromatic substrates with high isolated yields. Moreover, the catalysts proved to be efficient for a wide number of aliphatic substrates for selective C(sp3)-H bond borylations. Heterocyclic molecules are selectively borylated using the inherently elevated reactivity of the C-H bonds. A number of late-stage C-H functionalization have been described using the same catalysts. Furthermore, we show that one of the catalysts could be used even in open air for the C(sp2)-H and C(sp3)-H borylations enabling the method more general. Preliminary mechanistic studies suggest that the active catalytic intermediate is the Ir(bis)boryl complex, and the attached ligand acts as bidentate ligand. Collectively, this study underlines the discovery of new class of C-H borylation catalysts that should find wide application in the context of C-H functionalization chemistry.Floor space is a key variable used to understand the energy and material demands of buildings. Using recent data sets of building footprints, we employ a random forest regression model to estimate the total floor space (conditioned and unconditioned) of the North American building stock. Our estimate for total floor space in 2016 is 88033 (+15907/-21861) million m2, which is 2.9 times higher than current estimates from national statistics offices. We also show how floor space per capita (m2 cap-1) is not constant across the North American region, highlighting the heterogeneous nature of building stocks. As a critical variable in integrated assessment models to project energy and material demands, this result suggests that there is much more unconditioned floor space than previously realized. Furthermore, when estimating material stocks, flows, and associated embodied carbon emissions, total floor space per-capita estimates, such as those presented in this study, offer a more comprehensive approach in comparison to national statistics that do not capture unconditioned floor space. This result also calls for an investigation as to why there is such a vast difference between estimates of conditioned and total floor space.A freestanding ion membrane with high ionic conductivity, electrochemical compatibility, satisfactory strength, and safety is a goal pursued for advanced energy storage. Geminal dicationic ionic liquids (GDILs) are expected to be designed and synthesized as a basic building block for the target ionic conductors. Herein, we fabricated a GDIL-based flexible ion conductive material, which appears and behaves as a freestanding film, an ion membrane actually, denoted as iMembrane. The iMembrane presented high thermal stability, broad electrochemical stability, and capable ionic conductivity. Stable lithium-ion intercalation/de-intercalation can be achieved at the iMembrane/graphite interface without co-intercalation of imidazole rings, which is attributed to the specific anion-derived solid electrolyte interphase. Moreover, iMembrane is well compatible with the lithium metal anode and LiFePO4 cathode. The soft-packed batteries assembled with iMembrane were punctured with a nail without any fire or smoke. Hence, as an ionic membrane in nonprotonic, iMembrane is promising to enhance safety and energy density of lithium batteries.Acylphosphonates having the 5,5-dimethyl-1,3,2-dioxophosphinanyl skeleton are developed as efficient intermolecular radical acylation reagents, which enable the cobalt-catalyzed Markovnikov hydroacylation of unactivated alkenes at room temperature under mild conditions. The protocol exhibits broad substrate scope and wide functional group compatibility, providing branched ketones in satisfactory yields. A mechanism involving the Co-H mediated hydrogen atom transfer and subsequent trapping of alkyl radicals by acylphosphonates is proposed.Fibrosis is a pathological condition that leads to excessive deposition of collagen and increased tissue stiffness. Understanding the mechanobiology of fibrotic tissue necessitates the development of effective in vitro models that recapitulate its properties and structure; however, hydrogels that are currently used for this purpose fail to mimic the filamentous structure and mechanical properties of the fibrotic extracellular matrix (ECM). Here, we report a nanofibrillar hydrogel composed of cellulose nanocrystals and gelatin, which addresses this challenge. By altering the composition of the hydrogel, we mimicked the changes in structure, mechanical properties, and chemistry of fibrotic ECM. Furthermore, we decoupled the variations in hydrogel structure, properties, and ligand concentration. We demonstrate that this biocompatible hydrogel supports the three-dimensional culture of cells relevant to fibrotic diseases. This versatile hydrogel can be used for in vitro studies of fibrosis of different tissues, thus enabling the development of novel treatments for fibrotic diseases.
Homepage: https://www.selleckchem.com/products/pf-562271.html
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