From Node Interaction to Hop Interaction: New Effective and Scalable Graph Learning Paradigm

Existing Graph Neural Networks (GNNs) follow the message-passing mechanism that conducts information interaction among nodes iteratively. While considerable progress has been made, such node interaction paradigms still have the following limitation. First, the scalability limitation precludes the wide application of GNNs in large-scale industrial settings since the node interaction among rapidly expanding neighbors incurs high computation and memory costs. Second, the over-smoothing problem restricts the discrimination ability of nodes, i.e., node representations of different classes will converge to indistinguishable after repeated node interactions. In this work, we propose a novel hop interaction paradigm to address these limitations simultaneously. The core idea of hop interaction is to convert the target of message-passing from nodes into multi-hop features inside each node. Specifically, it first pre-computed multi-hop features of nodes to reduce computation costs during training and inference. Then, it conducts a non-linear interaction among multi-hop features to enhance the discrimination of nodes. We design a simple yet effective HopGNN framework that can easily utilize existing GNNs to achieve hop interaction. Furthermore, we propose a multi-task learning strategy with a self-supervised learning objective to enhance HopGNN. We conduct extensive experiments on 12 benchmark datasets in a wide range of domains, scales, and smoothness of graphs. Experimental results show that our methods achieve superior performance while maintaining high scalability and efficiency

Recent progress in anodic oxidation of TiO2 nanotubes and enhanced photocatalytic performance: a short review

© 2021 World Scientific Publishing Company. This is the accepted version of the final published version found at https://doi.org/10.1142/S1793292021300024By adjusting the oxidation voltage, electrolyte, anodizing time and other parameters, TiO2 nanotubes with high aspect ratio can be prepared by oxidation in organic system because anodic oxidation method has the advantage of simple preparation process, low material cost and controllable morphology. Low material cost and controllable morphology by anodizing. This review focuses on the influence of anodizing parameters on the morphology of TiO2 nanotube arrays prepared by anodizing. In order to improve the photocatalytic activity of TiO2 nanotubes under visible light and prolong the life of photo-generated carriers, the research status of improving the photocatalytic activity of TiO2 nanotubes in recent years is reviewed. This review focuses on the preparation and modification of TiO2 nanotubes by anodic oxidation, which is helpful to understand the best structure of TiO2 nanotubes and the appropriate modification methods, thus guiding the application of TiO2 nanotubes in practical photocatalysis. Finally, the development of TiO2 nanotubes is prospected.Peer reviewe

Topological insulator BSTS as a broadband switchable metamaterial

The development of metamaterials into a viable platform for nanophotonic applications, data processing circuits, sensors, etc. requires identification of new plasmonic materials to overcome the limitations of noble metals, in particular their high losses. Here we describe a class of topological insulator materials which support broadband plasmonic response and possess extremely appealing photonic properties ranging from mid-IR to UV. Bi1.5Sb0.5Te1.8Se1.2 (BSTS) is a bulk insulator with robust conducting surface states protected by time-reversal symmetry, due to the strong spin-orbit coupling. BSTS single crystals were synthesized by melting high-purity Bi, Sb, Te and Se powders at 950°C in an evacuated quartz tube. The temperature was then gradually decreased to room temperature over a span of three weeks. The resulting crystals were then cleaved along the (100) family of planes to a thickness of ~0.5 mm. BSTS dielectric constants were derived by ellipsometric measurements and appear to be in excellent agreement with first principle DFT calculations. Unlike common direct or indirect bandgap semiconductors, the anomalous dispersion region falls in the visible part of the spectrum, leading to negative values of the permittivity. This behavior of the optical response is attributed to a combination of bulk interband transitions and surface contribution of the topologically protected states. To prove metallic behavior of BSTS, we fabricated metamaterials and gratings on crystal flakes and registered strong plasmonic response from UV to NIR. The coexistence of plasmonic response of the topological surface with dielectric properties of the semiconducting bulk enables ultrafast (t>100 fs) and broadband (to mid-IR) photo-modulation of the optical response. These findings show the potential of topological insulators as a platform for high-frequency switchable plasmonic metamaterials

Plasmonic properties and photoinduced reflectance of topological insulator

We report on linear and nonlinear infrared and plasmonic properties of chalcogenide crystal of the Bi-Sb-Te-Se family that was recently identified as a prospective platform for switchable broadband plasmonic devices

Effect of Bagging on Wax Components and Storage Quality of ‘Yali’ Pear

In order to explore the effect of bagging on the wax compositions and storage quality of ‘Yali’ pear fruit, the differences and correlations of wax content and distribution, nutrition and quality indicators, and antioxidant properties of the two different treatments (polyethylene, (PE) plastic film bags and three-layer paper bags) stored at 25 ℃±1 ℃ were analyzed. The fruits were bagged at day 60 after blooming, then the bags were removed at harvest, and no-bagged fruit acted as the control. The results showed that the highest rate of fruit weight loss was found in PE plastic film bags-treated fruit, while there was no difference in fruit hardness, brittleness and compactness between the control and the two treatments within 14 days of storage. The increases in contents of wax compositions alkenes, fatty aldehydes, fatty alcohols, esters, and total wax were significantly delayed in the two treatments. The contents of alkanes C27 and C29, alkenes C24-C26, fatty acid C18:1, fatty aldehydes C26 and C34, even number fatty alcohols C22-C28, seven esters, and triterpenoids (such as α-farnesene, β-amyrin, lupeol, and β-amyrenone) in the two treatments were lower than the control. In addition, compared to the PE plastic film bags treatment, the decline in contents of wax compositions alkene C26, fatty acids C16 and C18:1, even number fatty aldehydes C28-C32, two esters (C22:1 alcohol-C18:1 acid and C24:1 alcohol-C18:1 acid), triterpenoids (Urs-12-en-28-al,3-(acetyloxy)-,(3á)-and Urs-12-en-28-al) were delayed by the three-layer paper bags treatment. Furthermore, in comparison with PE plastic film bags treatment, higher contents of peel flavonoids, peel total phenols (at day 14), fruit titratable acid and Vc (at day 14), and higher DPPH clearance rate were found in three-layer paper bags-treated fruit. According to PCA analysis of wax components, the control and the three-layer paper bags treatment were belonged to one group, while PE plastic film bags treatment was divided into the other group. The correlation analysis showed that wax components alkanes, fatty aldehydes, triterpenes and total wax in different treatments were positively correlated with the content of peel flavonoids (P<0.05), while fatty alcohols, esters and total wax were positively correlated with the content of fruit VC (P<0.05 or P<0.01). This study indicated that the three-layer paper bags treatment could delay the decline in accumulation of some fruit wax components, maintain the higher peel antioxidant capacity, and thus enhance fruit quality of ‘Yali’ pear

Alteration of Podocyte Protein Expression and Localization in the Early Stage of Various Hemodynamic Conditions

Given that podocalyxin (PCX) and nestin play important roles in podocyte morphogenesis and the maintenance of structural integrity, we examined whether the expression and localization of these two podocyte proteins were influenced in the early stage of various hemodynamic conditions. Mice kidney tissues were prepared by in vivo cryotechnique (IVCT). The distribution of glomeruli and podocyte proteins was visualized with DAB staining, confocal laser scanning microscopy and immunoelectron microscopy. The mRNA levels were examined by real-time quantitative PCR. The results showed the following: Under the normal condition, PCX stained intensely along glomerular epithelial cells, whereas nestin was clearly staining in the endothelial cells and appeared only weakly in the podocytes. Under the acute hypertensive and cardiac arrest conditions, PCX and nestin staining was not clear, with a disarranged distribution, but the colocalization of PCX and nestin was apparent under this condition. In addition, under the acute hypertensive and cardiac arrest conditions, the mRNA levels of PCX and nestin were significantly decreased. Collectively, the abnormal redistribution and decreased mRNA expressions of PCX and nestin are important molecular events at the early stage of podocyte injury during hemodynamic disorders. IVCT may have more advantages for morphological analysis when researching renal diseases

Mapping polarons in polymer FETs by charge modulation microscopy in the mid-infrared

We implemented spatial mapping of charge carrier density in the channel of a conventional polymer Field-Effect Transistor (FET) by mid-infrared Charge Modulation Spectroscopy (CMS). CMS spectra are recorded with a high sensitivity confocal Fourier Transform Infra-Red (FTIR) microscope by probing electroinduced Infra-Red Active Vibrational (IRAV) modes and low-energy polaron bands in the spectral region 680–4000 cm−1. Thanks to the high specificity and strong oscillator strength of these modes, charge-induced reflectance measurements allow quantitative estimation of charge carrier densities within the FET channel, without the need for amplitude or phase modulation. This is illustrated by identifying the contribution of intrinsic and electrostatically induced polarons to conduction, and by mapping the polaron spatial distribution in a P3HT (Poly(3-hexylthiophene-2,5-diyl)) FET channel under different drain-source bias conditions. This work demonstrates the potential of mid-infrared charge modulation microscopy to characterize carrier injection and transport in semiconducting polymer materials.Published versio

Electronic and optical properties of plasmonic topological insulators

Topological insulator (TI) crystals are bulk insulators with robust conducting surface states protected by time-reversal symmetry due to strong spin-orbit coupling (SOC). These TI materials have been widely investigated for spintronic applications and quantum computation [1], and now are considered emerging optical materials for surface plasmonics [2]. Among these TI materials, Bi2-xSbxTe3-ySey (BSTS) shows superior properties of large bulk resistance and surface-dominated transport, as well as negative permittivity and low-loss plasmonic resonances in the visible part of the spectrum [3]