Atrial fibrillation burden and the risk of stroke:A systematic review and dose-response meta-analysis

BACKGROUND The increased stroke risk associated with atrial fibrillation(AF)burden exceeding 5 min is a matter of debate.In addition,the potential linear or nonlinear relationship between AF burden and stroke risk has been largely unexplored.AIM To determine the association between AF burden>5 min and the increased risk of stroke and explore the potential dose-response relationship between these two factors.METHODS Sixteen studies from six databases with 53141 subjects(mean age 65 years)were included.Fifteen studies were observational studies,and one was a randomized controlled trial study.The potential nonlinear dose-response association was characterized using a restricted cubic splines regression model.AF burden for each 1 h and 2 h was associated with an increased risk of stroke.Trial sequential analysis with a random-effect model was used to evaluate the robustness of the evidence from the included 16 studies.RESULTS AF burden>5 min was associated with an increased risk of clinical AF[adjusted risk ratio(RR)=4.18,95%confidence interval(CI):2.26-7.74].However,no association was found with an increased risk of all-cause mortality(adjusted RR=1.55,95%CI:0.87-2.75).Patients with AF burden>5 min had an increased risk of stroke(adjusted RR=2.49,95%CI:1.79-3.47).Moreover,a dose-response analysis showed that the increased stroke risk was paralleled by an increase in AF burden at a rate of 2.0%per hour(Pnonlinear=0.656,RR=1.02,95%CI:1.01-1.03).Trial sequential analysis provided robust evidence of the association between AF burden>5 min and an increased risk of stroke.CONCLUSION AF burden was a significant risk factor for clinical AF and future stroke.A significant linear association was documented between increased AF burden and risk of future stroke.

Narrowband blue emitter based on fused nitrogen/carbonyl combination with external quantum efficiency approaching 30%

Multi-resonance thermally activated delayed fluorescence(MR-TADF)emitters can enable narrowband emission with high color purity and electroluminescence efficiency.Nitrogen/carbonyl(N/C=O)system is receiving increasing attention while the nitrogen/boron(N/B)system has been widely studied.Donor decoration is an effective approach for N/B type MR-TADF system but always leads to broadening and red-shifting of the emission band in N/C=O MR-TADF system.We attribute these unfavorable phenomena to the formation of intramolecular charge transfer between the MR-core and peripheral donors.To address this issue,we have developed a new strategy by decorating DMQAO(a fused N/C=O MR-core)with a triazine acceptor and a neutral terphenyl group to construct MTDMQAO and MBDMQAO,respectively.The introduction of the triazine acceptor not only realizes efficient narrowband emission in MTDMQAO,but also accelerates the reverse intersystem crossing process through enhanced spin-orbital coupling.As a result,MTDMQAO exhibits a significantly higher external quantum efficiency of 29.4%compared to the referent emitters,validating the rationality of our derivation strategy.This study highlights the potential of the N/C=O system for MR-TADF emitters and provides important insights for understanding the difference between N/B and N/C=O systems.

Spatial donor/acceptor architecture for intramolecular charge-transfer emitter

Charge transfer via electron hopping from an electron donor(D)to an acceptor(A)in nanoscale,plays a crucial role in optoelectronic materials,such as organic light-emitting diodes(OLEDs)and organic photovoltaic cells(OPVs).Here,we propose a strategy for binding D/A units in space,where intramolecular charge-transfer can take place.The resulted material DM-Me-B is able to give bright emission in this molecular architecture because of the good control of D/A interaction and conformational rigidity.Moreover,DM-Me-B presents small singlet-triplet splitting energy,enabling thermally activated delayed fluorescence.Therefore,the DM-Me-B exhibits~20%maximum external quantum efficiency and low efficiency roll-off at 1000 cd/m^(2),certifying an effective strategy in controlling D/A blocks through space.

π-Stacked host materials based on spirofluorene scaffolds for warm white OLEDs achieving 94.7 lm W^(-1) at 1,000 cd m^(-2)

Power efficiency(PE)at high brightness is considered as the rigorous standard of high-quality white organic light-emitting diodes(WOLEDs),for which the host material plays a significant role in energy conservation for practical lighting applications.Herein,PE is successfully enhanced to a new level through the method ofπ-stacked host molecular with spirofluorene scaffold.We design host materials by confining two donor units in a very short distance to enlarge theπ-electron spatial delocalization for facilitating the hole hopping process and engaging a rigid donor as the space-lock to suppress the quenching effect as well as induce host bipolar property.Based on this unique molecular design,the red,green,and blue(RGB)monochromic organic lightemitting diodes(OLEDs)demonstrate high external quantum efficiencies(EQEs)of 28.4%,26.0%,and 31.2%with ultralow roll-off,respectively.More encouragingly,the warm WOLEDs achieve record-high current efficiency(CE)of 109.5 cd A^(-1),PE of 109.1 lm W^(-1),and EQE of 32.9%.Even under operating brightness of 1,000 cd m^(-2),the devices can still realize 94.7 lm W^(-1)of PE,which represents the highest applicable PE value in the reported WOLEDs and for the first time single-host based WOLEDs with a performance exceeding that of a conventional fluorescent tube(70 lm W^(-1))without any light-extraction technique.

π-Stacked Thermally Activated Delayed Fluorescence Emitters with Alkyl Chain Modulation

Molecules bearing separateπ-electron donor(D)and acceptor(A)groups that undergo face-to-face D/A interactions have been utilized to develop thermally activated delayed fluorescence(TADF)materials.Theseπ-stacked D/A architectures are constructed on various scaffolds,which have either a long D/A distance or permitted conrotatory motion.Here,we develop a novel spiro-based scaffold with a short D/A distance and restricted circumvolution motions because of both the rigid spiro-scaffold and large rotation hindrance between the nearly coplanar D and A.We append different alkyl chains,which can modulate charge transfer and luminescence properties,at the nitrogen of the D moiety to develop four TADF molecules,which can modulate chargetransfer and luminescence properties.Because of the introduction of the solubilized alkyl chain,these molecules were used to fabricate solutionprocessed devices,among which a maximum external quantum efficiency of 18.9%was realized.By modulating interactions between the D/A building blocks,these TADF constructs exemplify that the alkyl side chains of TADF molecules,which used to be considered as solubilizing units,have vital impact on the optoelectronic properties and thus offer a new route to the design of solution-processable TADF emitters.