Graph is an important data representation which appears in a wide diversity of real-world scenarios. Effective graph analytics provides users a deeper understanding of what is behind the data, and ...thus can benefit a lot of useful applications such as node classification, node recommendation, link prediction, etc. However, most graph analytics methods suffer the high computation and space cost. Graph embedding is an effective yet efficient way to solve the graph analytics problem. It converts the graph data into a low dimensional space in which the graph structural information and graph properties are maximumly preserved. In this survey, we conduct a comprehensive review of the literature in graph embedding. We first introduce the formal definition of graph embedding as well as the related concepts. After that, we propose two taxonomies of graph embedding which correspond to what challenges exist in different graph embedding problem settings and how the existing work addresses these challenges in their solutions. Finally, we summarize the applications that graph embedding enables and suggest four promising future research directions in terms of computation efficiency, problem settings, techniques, and application scenarios.
In addition to a high specific capacitance, a large stretchability and self‐healing properties are also essential to improve the practicality and reliability of supercapacitors in portable and ...wearable electronics. However, the integration of multiple functions into one device remains challenging. Here, the construction of a highly stretchable and real‐time omni‐healable supercapacitor is demonstrated by sandwiching the polypyrrole‐incorporated gold nanoparticle/carbon nanotube (CNT)/poly(acrylamide) (GCP@PPy) hydrogel electrodes with a CNT‐free GCP (GP) hydrogel as the electrolyte and chemically soldering an Ag nanowire film to the hydrogel electrode as the current collector. The newly developed dynamic metal‐thiolate (M‐SR, M = Au, Ag) bond‐induced integrated configuration, with an intrinsically powerful electrode and electrolyte, enables the assembled supercapacitor to deliver an areal capacitance of 885 mF cm−2 and an energy density of 123 µWh cm−2, which are among the highest‐reported values for stretchable supercapacitors. Notably, the device exhibits a superhigh stretching strain of 800%, rapid optical healing capability, and significant real‐time healability during the charge–discharge process. The exceptional performance combined with the facile assembly method confirms this multifunctional device as the best performer among all the flexible supercapacitors reported to date.
A highly stretchable and real‐time omni‐healable supercapacitor is constructed by synergistically designing the entire device from the microstructures of the hydrogel electrode and electrolyte, to the interfacial interactions among the current collector, electrode, and electrolyte, and further to all‐in‐one device configuration via dynamic metal‐thiolate coordination chemistry. This supercapacitor shows great potential in the field of next‐generation flexible/wearable electronics.
The use of a chiral, emitting skeleton for axially chiral enantiomers showing activity in thermally activated delayed fluorescence (TADF) with circularly polarized electroluminescence (CPEL) is ...proposed. A pair of chiral stable enantiomers, (−)‐(S)‐Cz‐Ax‐CN and (+)‐(R)‐Cz‐Ax‐CN, was designed and synthesized. The enantiomers, both exhibiting intramolecular π‐conjugated charge transfer (CT) and spatial CT, show TADF activities with a small singlet–triplet energy difference (ΔEST) of 0.029 eV and mirror‐image circularly polarized luminescence (CPL) activities with large glum values. Notably, CP‐OLEDs based on the enantiomers feature blue electroluminescence centered at 468 nm with external quantum efficiencies (EQEs) of 12.5 and 12.7 %, and also show intense CPEL with gEL values of −1.2×10−2 and +1.4×10−2, respectively. These are the first CP‐OLEDs based on TADF‐active enantiomers with efficient blue CPEL.
Let's twist again: Axially chiral molecules with thermally activated delayed fluorescence and circularly polarized electroluminescence (CPEL) are presented. CP‐OLEDs based on these molecules display high efficiencies and blue CPEL with large gEL values.
An appropriate sample size is essential for obtaining a precise and reliable outcome of a study. In machine learning (ML), studies with inadequate samples suffer from overfitting of data and have a ...lower probability of producing true effects, while the increment in sample size increases the accuracy of prediction but may not cause a significant change after a certain sample size. Existing statistical approaches using standardized mean difference, effect size, and statistical power for determining sample size are potentially biased due to miscalculations or lack of experimental details. This study aims to design criteria for evaluating sample size in ML studies. We examined the average and grand effect sizes and the performance of five ML methods using simulated datasets and three real datasets to derive the criteria for sample size. We systematically increase the sample size, starting from 16, by randomly sampling and examine the impact of sample size on classifiers' performance and both effect sizes. Tenfold cross-validation was used to quantify the accuracy.
The results demonstrate that the effect sizes and the classification accuracies increase while the variances in effect sizes shrink with the increment of samples when the datasets have a good discriminative power between two classes. By contrast, indeterminate datasets had poor effect sizes and classification accuracies, which did not improve by increasing sample size in both simulated and real datasets. A good dataset exhibited a significant difference in average and grand effect sizes. We derived two criteria based on the above findings to assess a decided sample size by combining the effect size and the ML accuracy. The sample size is considered suitable when it has appropriate effect sizes (≥ 0.5) and ML accuracy (≥ 80%). After an appropriate sample size, the increment in samples will not benefit as it will not significantly change the effect size and accuracy, thereby resulting in a good cost-benefit ratio.
We believe that these practical criteria can be used as a reference for both the authors and editors to evaluate whether the selected sample size is adequate for a study.
Aromatic‐imide‐based thermally activated delayed fluorescent (TADF) enantiomers, (+)‐(S,S)‐CAI‐Cz and (−)‐(R,R)‐CAI‐Cz, were efficiently synthesized by introducing a chiral 1,2‐diaminocyclohexane to ...the achiral TADF unit. The TADF enantiomers exhibited high PLQYs of up to 98 %, small ΔEST values of 0.06 eV, as well as obvious temperature‐dependent transient PL spectra, thus demonstrating their excellent TADF properties. Moreover, the TADF enantiomers showed mirror‐image CD and CPL activities. Notably, the CP‐OLEDs with CPEL properties based on the TADF enantiomers not only achieved high EQE values of up to 19.7 and 19.8 %, but also displayed opposite CPEL signals with gEL values of −1.7×10−3 and 2.3×10−3, which represents the first CP‐OLEDs, based on the enantiomerically pure TADF materials, having both high efficiencies and intense CPEL.
It's intense: Thermally activated delayed fluorescenct (TADF) enantiomers were developed by introducing a chiral 1,2‐diaminocyclohexane to the achiral TADF unit. They exhibited high PLQYs (98 %), small ΔEST values (0.06 eV), and mirror‐image CD and CPL spectra. Moreover, they represent the first example of CP‐OLEDs, based on the enantiomerically pure TADF materials, having both high efficiencies (EQE: 19.8 %) and intense CPEL.
A nonconventional U(1)e−μ gauge model is proposed to explain the observed neutrino masses and the unexpected anomalous magnetic moments of the electron and muon (lepton g−2), where for suppressing ...the neutrino coupling to Z′ gauge boson, only the right-handed electron and muon in the standard model carry the U(1)e−μ charge. Although the light lepton masses are suppressed when the gauge symmetry is spontaneously broken, they can be generated through the Yukawa couplings to newly introduced particles, such as vector-like lepton doublets and singlets, and scalar singlets. It is found that the same Yukawa couplings combined with the new scalar couplings to the Higgs can induce the radiative lepton-flavor violation processes ℓ′→ℓγ and lepton g−2, where the lepton g−2 is proportional to mℓ. When Majorana fermions and a scalar singlet are further added into the model, the active neutrinos can obtain masses via the radiative seesaw mechanism. When the bounds from the me and mμ and the neutrino data are satisfied, we find that the electron g−2 can reach an order of −10−12, and the muon g−2 can be an order of 10−9. In addition, when the μ→eγ decay is suppressed, the resulting branching ratio for τ→eγ can be of O(10−8), and that for τ→μγ can be as large as the current upper limit.
The features of well-conjugated and planar aromatic structures make π-conjugated luminescent materials suffer from aggregation caused quenching (ACQ) effect when used in solid or aggregated states, ...which greatly impedes their applications in optoelectronic devices and biological applications. Herein, we reduce the ACQ effect by demonstrating a facile and low cost method to co-assemble polycyclic aromatic hydrocarbon (PAH) chromophores and octafluoronaphthalene together. Significantly, the solid photoluminescence quantum yield (PLQYs) for the as-resulted four micro/nanococrystals are enhanced by 254%, 235%, 474 and 582%, respectively. Protection from hydrophilic polymer chains (P123 (PEO
-PPO
-PEO
)) endows the cocrystals with superb dispersibility in water. More importantly, profiting from the above-mentioned highly improved properties, nano-cocrystals present good biocompatibility and considerable cell imaging performance. This research provides a simple method to enhance the emission, biocompatibility and cellular permeability of common chromophores, which may open more avenues for the applications of originally non- or poor fluorescent PAHs.
Macrocycles denoted as saucernarenes (n=4,5) were easily synthesized by the one‐pot condensation of 2,7‐dimethoxynaphthalene (2,7‐DMN) and paraformaldehyde in the presence of TFA or catalytic ...BF3⋅OEt2. With 1,1‐dimethylpiperidin‐1‐ium as the template, saucer4arene was selectively obtained. Crystal structures show that saucernarenes are all composed of 2,7‐DMN moiety bridged by the methylene groups at 1,6‐positions: all of the 7‐methoxy groups lie on one face, and all of the 2‐methoxy groups lie on the other. Saucernarenes exhibit strong fluorescence properties with the quantum yields of 19.6 % and 23.4 %. They form 1:1 complexes with ammonium salts in both solution and solid state (association constant up to 105 M−1 in CDCl3). Chiral quaternary ammonium salts can induce the chirality of the dynamically racemic inherently chiral saucernarenes in solution, and thus show mirror‐imaged circular dichroism signals and circularly polarized luminescence (CPL) properties.
Starting from 2,7‐dimethoxynaphthalene, a new kind of macrocyclic arenes named saucernarenes (n=4,5) are synthesized by one‐pot and templated methods. Saucernarenes show strong fluorescence properties and form 1:1 complexes with various ammonium salts. Moreover, the chiral guests can induce the chirality of dynamically racemic saucernarenes in the host–guest systems, which provides a new way to construct CPL organic materials.
In this study, we investigate muon g−2, RK(⁎), and RD(⁎) anomalies in a specific model with one doublet, one triplet, and one singlet scalar leptoquark (LQ). When the strict limits from the ℓ′→ℓγ, ...ΔB=2, Bs→μ+μ−, and B+→K+νν¯ processes are considered, it is difficult to use one scalar LQ to explain all of the anomalies due to the strong correlations among the constraints and observables. After ignoring the constraints and small couplings, the muon g−2 can be explained by the doublet LQ alone due to the mt enhancement, whereas the measured and unexpected smaller RK(⁎) requires the combined effects of the doublet and triplet LQs, and the RD and RD⁎ excesses depend on the singlet LQ through scalar- and tensor-type interactions.
A supramolecular strategy to construct thermally activated delayed fluorescence (TADF) materials through host–guest charge transfer interactions was proposed. Consequently, a new class of macrocycle ...namely calix3acridan was conveniently synthesized in 90 % yield. The host–guest cocrystal formed by calix3acridan and 1,2‐dicyanobenzene exhibited efficient TADF properties due to intense intermolecular charge transfer interactions. Moreover, the spatially separated highest occupied molecular orbital and lowest unoccupied molecular orbital resulted in a very small singlet–triplet energy gap of 0.014 eV and hence guaranteed an efficient reverse intersystem crossing for TADF. Especially, a high photoluminescence quantum yield of 70 % was achieved, and it represents the highest value among the reported intermolecular donor–acceptor TADF materials.
A novel supramolecular strategy to construct thermally activated delayed fluorescence (TADF) materials has been developed, which has led to the convenient synthesis of a new kind of macrocycle, namely calix3acridan. The host–guest cocrystal formed from calix3acridan and 1,2‐dicyanobenzene exhibited efficient TADF with a high photoluminescence quantum yield of 70 % as a result of intense intermolecular charge transfer (ICT).
PDF
