Circularly polarized organic light‐emitting diodes (CP‐OLEDs) are particularly favorable for the direct generation of CP light, and they demonstrate a promising application in 3D display. However, up ...to now, such CP devices have suffered from low brightness, insufficient efficiency, and serious efficiency roll‐off. In this study, a pair of octahydro‐binaphthol (OBN)‐based chiral emitting enantiomers, (R/S)‐OBN‐Cz, are developed by ingeniously merging a chiral source and a luminophore skeleton. These chirality–acceptor–donor (C–A–D)‐type and rod‐like compounds concurrently generate thermally activated delayed fluorescence with a small ΔEST of 0.037 eV, as well as a high photoluminescence quantum yield of 92% and intense circularly polarized photoluminescence with dissymmetry factors (|gPL|) of ≈2.0 × 10−3 in thin films. The CP‐OLEDs based on (R/S)‐OBN‐Cz enantiomers not only display obvious circularly polarized electroluminescence signals with a |gEL| of ≈2.0 × 10−3, but also exhibit superior efficiencies with maximum external quantum efficiency (EQEmax) up to 32.6% and extremely low efficiency roll‐off with an EQE of 30.6% at 5000 cd m−2, which are the best performances among the reported CP devices to date.
Octahydrobinaphthol‐compound‐based circularly polarized delayed fluorescence enantiomers, (R/S)‐OBN‐Cz are developed by merging a chiral source and a luminophore skeleton. The circularly polarized organic light‐emitting diodes based on (R/S)‐OBN‐Cz display intense CP‐electroluminescence signals with a |gEL| of ≈2.0 × 10−3, and achieve superior efficiencies with external quantum efficiency (EQE) up to 32.6% and extremely low efficiency roll‐off with an EQE of 30.6% at 5000 cd m−2.
Pure organic materials with intrinsic room‐temperature phosphorescence typically rely on heavy atoms or heteroatoms. Two different strategies towards constructing organic room‐temperature ...phosphorescence (RTP) species based upon the through‐space charge transfer (TSCT) unit of 2.2paracyclophane (PCP) were demonstrated. Materials with bromine atoms, PCP‐BrCz and PPCP‐BrCz, exhibit RTP lifetime of around 100 ms. Modulating the PCP core with non‐halogen‐containing electron‐withdrawing units, PCP‐TNTCz and PCP‐PyCNCz, successfully elongate the RTP lifetime to 313.59 and 528.00 ms, respectively, the afterglow of which is visible for several seconds under ambient conditions. The PCP‐TNTCz and PCP‐PyCNCz enantiomers display excellent circular polarized luminescence with dissymmetry factors as high as −1.2×10−2 in toluene solutions, and decent RTP lifetime of around 300 ms for PCP‐TNTCz enantiomers in crystalline state.
A series of organic phosphors based on paracyclophanes (PCPs) exhibit both strong room‐temperature phosphorescence (RTP) and excellent circularly polarized luminescence. Modulating the PCP core with non‐halogen‐containing electron‐withdrawing units elongates the RTP lifetime to 313.59 and 528.00 ms. The afterglow is visible for several seconds under ambient conditions.
A spiro‐axis skeleton not only introduces circularly polarized luminescence (CPL) into thermally activated delayed fluorescence (TADF) molecules but also enhances the intramolecular through space ...charge transfer (TSCT) process. Spiral distributed phenoxazine and 2‐(trifluoromethyl)‐9H‐thioxanthen‐9‐one‐10,10‐dioxide act as donor and acceptor units, respectively. The resulting TADF enantiomers, (rac)‐OSFSO, display emission maxima at 470 nm, small singlet‐triplet energy gap (ΔEST) of 0.022 eV and high photoluminescence quantum yield (PLQY) of 81.2 % in co‐doped film. The circularly polarized OLEDs (CP‐OLEDs) based on (R)‐OSFSO and (S)‐OSFSO display obvious circularly polarized electroluminescence (CPEL) signals with dissymmetry factor up to 3.0×10−3 and maximum external quantum efficiency (EQEmax) of 20.0 %. Moreover, the devices show remarkably low efficiency roll‐off with an EQE of 19.3 % at 1000 cd m−2 (roll‐off ca. 3.5 %), which are among the top results of CP‐OLEDs.
A chiral spiro‐axis skeleton introduced the circularly polarized luminescence property into TADF molecules and enhanced the intramolecular through space charge transfer process. The resulting TADF enantiomers display obvious CPEL signals with |gEL| factor up to 3.0×10−3 and EQE of 20.0 % with remarkably low efficiency roll‐off, which are among the top results of CP‐OLEDs.
Upland forests are traditionally thought to be net sinks for atmospheric methane (CH4). In such forests, in situ CH4 fluxes on tree trunks have been neglected relative to soil and canopy fluxes.
We ...measured in situ CH4 fluxes from the trunks of living trees and other surfaces, such as twigs and soils, using a static closed-chamber method, and estimated the CH4 budget in a temperate upland forest in Beijing.
We found that the trunks of Populus davidiana emitted large quantities of CH4 during July 2014–July 2015, amounting to mean annual emissions of 85.3 and 103.1 μg m−2 h−1 on a trunk surface area basis on two replicate plots. The emission rates were similar in magnitude to those from tree trunks in wetland forests. The emitted CH4 was derived from the heartwood of trunks. On a plot or ecosystem scale, trunk CH4 emissions were equivalent to c. 30–90% of the amount of CH4 consumed by soils throughout the year, with an annual average of 63%.
Our findings suggest that wet heartwoods, regardless of rot or not, occur widely in living trees on various habitats, where CH4 can be produced.
The Majorana fermion, which is its own antiparticle and obeys non-Abelian statistics, plays a critical role in topological quantum computing. It can be realized as a bound state at zero energy, ...called a Majorana zero mode (MZM), in the vortex core of a topological superconductor, or at the ends of a nanowire when both superconductivity and strong spin orbital coupling are present. A MZM can be detected as a zero-bias conductance peak (ZBCP) in tunneling spectroscopy. However, in practice, clean and robust MZMs have not been realized in the vortices of a superconductor because of contamination from impurity states or other closely packed Caroli–de Gennes-Matricon (CdGM) states, which hampers further manipulations of MZMs. Here, using scanning tunneling spectroscopy, we show that a ZBCP well separated from the other discrete CdGM states exists ubiquitously in the cores of free vortices in the defect-free regions of(Li0.84Fe0.16)OHFeSe, which has a superconducting transition temperature of 42 K. Moreover, a Dirac-cone-type surface state is observed by angle-resolved photoemission spectroscopy, and its topological nature is confirmed by band calculations. The observed ZBCP can naturally be attributed to a MZM arising from the chiral topological surface state of a bulk superconductor. Thus,(Li0.84Fe0.16)OHFeSeprovides an ideal platform for studying MZMs and topological quantum computing.
Chiral materials with circularly polarized luminescence (CPL) are potentially applicable for 3D displays. In this study, by decorating the pyridinyl‐helicene ligands with ‐CF3 and ‐F groups, the ...platinahelicene enantiomers featured superior configurational stability, as well as high sublimation yield (>90 %) and clear CPPL properties, with dissymmetry factors (|gPL|) of approximately 3.7×10−3 in solution and about 4.1×10−3 in doped film. The evaporated circularly polarized phosphorescent organic light‐emitting diodes (CP‐PhOLEDs) with two enantiomers as emitters exhibited symmetric CPEL signals with |gEL| of (1.1–1.6)×10−3 and decent device performances, achieving a maximum brightness of 11 590 cd m−2, a maximum external quantum efficiency up to 18.81 %, which are the highest values among the reported devices based on chiral phosphorescent PtII complexes. To suppress the effect of reverse CPEL signal from the cathode reflection, the further implementation of semitransparent aluminum/silver cathode successfully boosts up the |gEL| by over three times to 5.1×10−3.
Two platinahelicene enantiomers with configurational stability and good CPPL property were used as emitters in efficient evaporated circularly polarized phosphorescent organic light‐emitting diodes (CP‐PhOLEDs). A maximum brightness of 11 590 cd m−2, a maximum external quantum efficiency up to 18.81 %, and symmetric CPEL signals with |gEL| of (1.1–1.6)×10−3 were achieved. Further implementation of semitransparent silver/aluminum cathode successfully boosted up the |gEL| by over three times to 5.1×10−3.
Background and Aims
Hepatic ischemia–reperfusion injury (IRI) is a common complication of hepatectomy and liver transplantation. However, the mechanisms underlying hepatic IRI have not been fully ...elucidated. Regulator of G‐protein signaling 14 (RGS14) is a multifunctional scaffolding protein that integrates the G‐protein and mitogen‐activated protein kinase (MAPK) signaling pathways. However, the role of RGS14 in hepatic IRI remains unclear.
Approach and Results
We found that RGS14 expression increased in mice subjected to hepatic ischemia–reperfusion (IR) surgery and during hypoxia reoxygenation in hepatocytes. We constructed global RGS14 knockout (RGS14‐KO) and hepatocyte‐specific RGS14 transgenic (RGS14‐TG) mice to establish 70% hepatic IRI models. Histological hematoxylin and eosin staining, levels of alanine aminotransferase and aspartate aminotransferase, expression of inflammatory factors, and apoptosis were used to assess liver damage and function in these models. We found that RGS14 deficiency significantly aggravated IR‐induced liver injury and activated hepatic inflammatory responses and apoptosis in vivo and in vitro. Conversely, RGS14 overexpression exerted the opposite effect of the RGS14‐deficient models. Phosphorylation of TGF‐β‐activated kinase 1 (TAK1) and its downstream effectors c‐Jun N‐terminal kinase (JNK) and p38 increased in the liver tissues of RGS14‐KO mice but was repressed in those of RGS14‐TG mice. Furthermore, inhibition of TAK1 phosphorylation rescued the effect of RGS14 deficiency on JNK and p38 activation, thus blocking the inflammatory responses and apoptosis.
Conclusions
RGS14 plays a protective role in hepatic IR by inhibiting activation of the TAK1–JNK/p38 signaling pathway. This may be a potential therapeutic strategy for reducing incidences of hepatic IRI in the future.
High-performance pervaporation membranes have potential in industrial separation applications, but overcoming the permeability-selectivity trade-off is a challenge. We report a strategy to create ...highly flexible metal-organic framework nanosheet (MOF-NS) membranes with a faveolate structure on polymer substrates for alcohol-water separation. The controlled growth followed by a surface-coating method effectively produced flexible and defect-free superhydrophobic MOF-NS membranes. The reversible deformation of the flexible MOF-NS and the vertical interlamellar pathways were captured with electron microscopy. Molecular simulations confirmed the structure and revealed transport mechanism. The ultrafast transport channels in MOF-NS exhibited an ultrahigh flux and a separation factor of 8.9 in the pervaporation of 5 weight % ethanol-water at 40°C, which can be used for biofuel recovery. MOF-NS and polydimethylsiloxane synergistically contribute to the separation performance.
Honeycomb channels enhance separations
Pervaporation membranes use a combination of permeation and evaporation for energy-efficient separations of volatile compounds from solutions. Xu
et al
. designed a strategy to fabricate defect-free superhydrophobic metal-organic framework (MOF) nanosheet membranes. Instead of dispersing the MOFs into a polydimethylsiloxane (PDMS) matrix, the authors grew a continuous and uniform layer of embedded MOF seeds on polymeric substrates that were then sealed with PDMS. This procedure results in a honeycomb-like structure with high flexibility and fast molecular transport channels, thus enhancing the separation of alcohols from water. —MSL
Flexible metal-organic framework honeycombed nanosheet membranes are applied for alcohol-water separations.
Background
Thyroid carcinoma (TC) has been a global issue for its rapid increasing incidence worldwide. Although most TC was not so aggressive with a good prognosis, treatment against anaplastic TC ...was relatively limited and the mechanisms are not well elucidated yet.
Methods
TC cell lines (IHH4 and TPC‐1) were used. Flow cytometry was used to identify the surface marker of M2‐like tumor‐associated macrophages (TAMs) from cell culture. Quantitative real‐time polymerase chain reaction, western blot analysis, immunostaining, and immunohistochemistry were used to detect the expression of Wnt1, Wnt3a, components of Wnt/β‐catenin pathway, and proliferation/epithelial–mesenchymal transition (EMT)‐related proteins. Alkaline phosphatase activity assay, colony formation assay, and transwell assay were used to examine the roles of Wnt1, Wnt3a, and β‐catenin pathway in cell dedifferentiation, proliferation, migration, and invasion of TC cells, respectively. Subcutaneous tumor growth was monitored in nude mice.
Results
Coculture with M2‐like TAMs facilitated dedifferentiation, proliferation, migration, and invasion in TC cells. EMT and proliferation‐related proteins were also promoted in cocultured TC cells. The level of Wnt1 and Wnt3a was increased in the coculture system. Block of Wnt1 or Wnt3a suppressed malignant behaviors in cocultured tumor cells. Furthermore, Wnt1 or Wnt3a knockdown inhibited Wnt/β‐catenin signaling pathway, and suppressed EMT and proliferation‐related signals in cocultured tumor cells. Knockdown of Wnt1 or Wnt3a inhibited tumor growth in xenograft model.
Conclusion
M2‐like TAMs promoted dedifferentiation, proliferation, and metastasis of TC by Wnt1 and Wnt3a secretion and ensuing β‐catenin activation.
Recent development of most organic long persistent luminescence (OLPL) systems employed binary or tertiary doping. However, the design strategies towards OLPL materials with hour‐long afterglow ...duration are still quite limited. Here, we propose a novel OLPL system through melt‐casting method with 0.1 mol % of CuI complexes: 2,2′‐bis(diphenylphosphino)‐1,1′‐binaphthyl BINAP‐CuX (X=Cl, Br and I) doped into the triphenylphosphine (TPP) host. The charge separation was initiated prior to excitation through host coordination with CuI complexes, resulting in semi‐free halogen ions and in situ generated CuI cations, which forms TPP + BINAP‐CuX ionic pairs and subsequently ionic solids. The OLPL lifetime can be readily modulated by different halogen atoms and the afterglow can last up to more than 3 hours perceivable to human eyes. This is a rare example of OLPL initiated through host‐guest coordination that could potentially expand the definition of OLPL systems and design strategies.
An organic long persistent luminescence (OLPL) system based on in situ generated ionic pairs with CuI centers is proposed and demonstrated. Intermediates are proposed and verified through a series of carefully designed experiments. The afterglow of corresponding blends can last more than 3 hours, thus this mechanism is the first to incorporate CuI ions in OLPL systems.
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