An unsupervised domain adaptation method towards multi-level features and decision boundaries for cross-scene hyperspectral image classification.

Despite success in the same-scene hyperspectral image classification (HSIC), for the cross-scene classification, samples between source and target scenes are not drawn from the independent and identical distribution, resulting in significant performance degradation. To tackle this issue, a novel unsupervised domain adaptation (UDA) framework toward multilevel features and decision boundaries (ToMF-B) is proposed for the cross-scene HSIC, which can align task-related features and learn task-specific decision boundaries in parallel. Based on the maximum classifier discrepancy, a two-stage alignment scheme is proposed to bridge the interdomain gap and generate discriminative decision boundaries. In addition, to fully learn task-related and domain-confusing features, a convolutional neural network (CNN) and Transformer-based multilevel features extractor (generator) is developed to enrich the feature representation of two domains. Furthermore, to alleviate the harm even the negative transfer to UDA caused by task-irrelevant features, a task-oriented feature decomposition method is leveraged to enhance the task-related features while suppressing task-irrelevant features, and enabling the aligned domain-invariant features can be contributed to the classification task explicitly. Extensive experiments on three cross-scene HSI benchmarks have validated the effectiveness of the proposed framework

Experimentally Validated Structures of Supported Metal Nanoclusters on MoS₂

In nanometer clusters (NCs), each atom counts. It is the specific arrangement of these atoms that determines the unique size-dependent functionalities of the NCs and hence their applications. Here, we employ a self-consistent, combined theoretical and experimental approach to determine atom-by-atom the structures of supported Pt NCs on MoS₂. The atomic structures are predicted using a genetic algorithm utilizing atomistic force fields and density functional theory, which are then validated using aberration-corrected scanning transmission electron microscopy. We find that relatively small clusters grow with (111) orientation such that Pt[11̅0] is parallel to MoS₂[100], which is different from predictions based on lattice-match for thin-film epitaxy. Other 4d and 5d transition metals show similar behavior. The underpinning of this growth mode is the tendency of the NCs to maximize the metal–sulfur interactions rather than to minimize lattice strain

Pyrimidine-Based Mononuclear and Dinuclear Iridium(III) Complexes for High Performance Organic Light-Emitting Diodes

Containing two nitrogen atoms, the electron-deficient pyrimidine ring has excellent coordinating capability with transition metal ions. However, compared with the widely used pyridine ring, applications of the pyrimidine ring in phosphorescent Ir­(III) complexes are rare. In this research, two highly emissive pyrimidine-based mononuclear Ir­(III) complexes and their corresponding dinuclear Ir­(III) complexes were prepared with a simple one-pot reaction. The incorporation of the second Ir­(III) center can lead to dramatic differences of both photophysical and electrochemical properties between the mono- and dinuclear complexes. Besides, these properties can also be fine-tuned with different substituents. Theoretical calculations have also been performed to understand their photophysical behaviors. The electroluminescent investigations demonstrate that the pyrimidine-based mono- and dinuclear Ir­(III) complexes could show impressive device performance. The vacuum-deposited organic light-emitting diode (OLED) based on the mononuclear Ir­(III) complex exhibited an external quantum efficiency (EQE) of 16.1% with almost no efficiency roll-off even at 10 000 cd m^–2. More encouragingly, the solution-processed OLED based on the dinuclear Ir­(III) complex achieved the outstanding EQE, current efficiency (CE), and power efficiency (PE) of 17.9%, 52.5 cd A^–1, and 51.2 lm W^–1, respectively, representing the highest efficiencies ever achieved by OLEDs based on dinuclear Ir­(III) complexes

Asymmetric <i>tris</i>-Heteroleptic Iridium^III Complexes Containing a 9‑Phenyl-9-phosphafluorene Oxide Moiety with Enhanced Charge Carrier Injection/Transporting Properties for Highly Efficient Solution-Processed Organic Light-Emitting Diodes

A cyclometalating ligand containing a 9-phenyl-9-phosphafluorene oxide (PhFlPO) moiety has been synthesized and used to construct asymmetric <i>tris</i>-heteroleptic cyclometalating Ir^III complexes in combination with other ppy-type (Hppy = 2-phenylpyridine) ligands containing a functional group with a different charge carrier injection/transporting character. Their photophysical properties, electrochemical behaviors, and electroluminescent (EL) performances have been characterized in detail. Time-dependent density functional theory (TD-DFT) and natural transition orbital (NTO) calculation were carried out to gain insight into the photophysical properties of these complexes. The NTO results show that the characters of the lowest triplet excited states (T₁) can be delicately manipulated through the combination of different cyclometalating ligands. In addition, the strong electron injection/transporting (EI/ET) ability associated with the PhFlPO moiety can confer EI/ET properties to the asymmetric <i>tris</i>-heteroleptic cyclometalating Ir^III complexes. Consequently, the solution-processed organic light-emitting diodes/devices (OLEDs) based on these asymmetric <i>tris</i>-heteroleptic Ir^III phosphorescent complexes can exhibit outstanding electroluminescent (EL) performances with the maximum external quantum efficiency (η_ext) of 19.3%, current efficiency (η_L) of 82.5 cd A^–1, and power efficiency (η_P) of 57.3 lm W^–1 for the yellow-emitting device. These results show the great potential of a PhFlPO moiety in developing phosphorescent emitters and functional materials with excellent EI/ET properties

Deciphering the causal relationship between blood pressure and regional white matter integrity: A two-sample Mendelian randomization study

Elevated arterial blood pressure (BP) is a common risk factor for cerebrovascular and cardiovascular diseases, but no causal relationship has been established between BP and cerebral white matter (WM) integrity. In this study, we performed a two-sample Mendelian randomization (MR) analysis with individual-level data by defining two nonoverlapping sets of European ancestry individuals (genetics–exposure set: N = 203,111; mean age = 56.71 years, genetics–outcome set: N = 16,156; mean age = 54.61 years) from UK Biobank to evaluate the causal effects of BP on regional WM integrity, measured by fractional anisotropy of diffusion tensor imaging. Two BP traits: systolic and diastolic blood pressure were used as exposures. Genetic variant was carefully selected as instrumental variable (IV) under the MR analysis assumptions. We existing large-scale genome-wide association study summary data for validation. The main method used was a generalized version of inverse-variance weight method while other MR methods were also applied for consistent findings. Two additional MR analyses were performed to exclude the possibility of reverse causality. We found significantly negative causal effects (FDR-adjusted p < .05; every 10 mmHg increase in BP leads to a decrease in FA value by .4% ~ 2%) of BP traits on a union set of 17 WM tracts, including brain regions related to cognitive function and memory. Our study extended the previous findings of association to causation for regional WM integrity, providing insights into the pathological processes of elevated BP that might chronically alter the brain microstructure in different regions.https://doi.org/10.1002/jnr.2520

High Triplet Energy Level Achieved by Tuning the Arrangement of Building Blocks in Phosphorescent Polymer Backbones for Furnishing High Electroluminescent Performances in Both Blue and White Organic Light-Emitting Devices

A high triplet energy level (<i>E</i>_T) of ca. 2.83 eV has been achieved in a novel polymer backbone through tuning the arrangement of two kinds of building blocks, showing enhanced hole injection/transporting capacity. Based on this new polymer backbone with high <i>E</i>_T, both blue and white phosphorescent polymers were successfully developed with a trade-off between high <i>E</i>_T and enhanced charge-carrier transporting ability. In addition, their photophysical features, electrochemical behaviors, and electroluminescent (EL) properties have been characterized in detail. Benefitting from the advantages associated with the novel polymer backbone, the blue phosphorescent polymers show top-ranking EL performances with a maximum luminance efficiency (η_L) of 15.22 cd A^–1, corresponding to a power efficiency (η_P) of 12.64 lm W^–1, and external quantum efficiency (η_ext) of 6.22% and the stable Commission Internationale de L’Eclairage (CIE) coordinates of (0.19, 0.38). Furthermore, blue–orange (B–O) complementary-colored white phosphorescent polymers based on this novel polymer backbone were also obtained showing encouraging EL efficiencies of 12.34 cd A^–1, 9.59 lm W^–1, and 4.10% in the optimized WOLED together with exceptionally stable CIE coordinates of (Δ<i>x</i> = 0.014, Δ<i>y</i> = 0.010) in a wide driving voltage range from 4 to 16 V. All of these attractive EL results achieved by these novel phosphorescent polymers show the great potential of this new polymer backbone in developing highly efficient phosphorescent polymers