BatmanNet: Bi-branch Masked Graph Transformer Autoencoder for Molecular Representation

Although substantial efforts have been made using graph neural networks (GNNs) for AI-driven drug discovery (AIDD), effective molecular representation learning remains an open challenge, especially in the case of insufficient labeled molecules. Recent studies suggest that big GNN models pre-trained by self-supervised learning on unlabeled datasets enable better transfer performance in downstream molecular property prediction tasks. However, they often require large-scale datasets and considerable computational resources, which is time-consuming, computationally expensive, and environmentally unfriendly. To alleviate these limitations, we propose a novel pre-training model for molecular representation learning, Bi-branch Masked Graph Transformer Autoencoder (BatmanNet). BatmanNet features two tailored and complementary graph autoencoders to reconstruct the missing nodes and edges from a masked molecular graph. To our surprise, BatmanNet discovered that the highly masked proportion (60%) of the atoms and bonds achieved the best performance. We further propose an asymmetric graph-based encoder-decoder architecture for either nodes and edges, where a transformer-based encoder only takes the visible subset of nodes or edges, and a lightweight decoder reconstructs the original molecule from the latent representation and mask tokens. With this simple yet effective asymmetrical design, our BatmanNet can learn efficiently even from a much smaller-scale unlabeled molecular dataset to capture the underlying structural and semantic information, overcoming a major limitation of current deep neural networks for molecular representation learning. For instance, using only 250K unlabelled molecules as pre-training data, our BatmanNet with 2.575M parameters achieves a 0.5% improvement on the average AUC compared with the current state-of-the-art method with 100M parameters pre-trained on 11M molecules.Comment: 11 pages, 3 figure

Metagenomic Profiling of the Bacterial Community Changes from Koji to Mash Stage in the Brewing of Soy Sauce

The improvement of soy sauce fermentation is restricted by the insufficient information on bacterial community. In this study, bacterial communities in the koji and mash stage were compared based on next-generation sequencing technology. A total of 29 genera were identi­fied in the koji stage, while 34 in the mash stage. After koji stage, 7 genera disappeared and 12 new genera appeared in the mash stage. The dominant bacteria were Kurthia, Weissella and Staphylococcus in the koji stage and Staphylococcus, Kurthia, Enterococcus and Leuconostoc in the mash stage. The results provided insights into the microbial communities involved in soy sauce fermentation

Self-starting harmonic frequency comb generation in a quantum cascade laser

Engineering and Applied Science

Generic oscillations of delay differential system with impulses

AbstractIn this paper, we will study generic oscillation and generic nonoscillation of impulsive delay differential system. Some necessary and sufficient conditions and sufficient conditions are obtained for both phenomena based on the root of characteristic equation

Corrosion characteristics and mechanism of 6082/AZ31/6082 laminated metal composites in tropical marine atmospheric environments

The preparation of Al/Mg/Al laminated metal composites (LMCs) by lamination technique can well combine the good corrosion resistance of Al alloy and the lightweight characteristics of Mg alloy. In this paper, the atmospheric corrosion behavior and underlying mechanism of 6082/AZ31/6082 LMCs with and without side exposure for one year of filed exposure to the tropical marine atmospheric environment were investigated. The results showed that the corrosion rates of AZ31 and 6082 and LMC-C were 55.967, 1.167, and 0.925 g m−2·a−1, respectively. The microstructure of the Al layer on the surface of LMCs underwent a significant transformation, characterized by a noticeable grain refinement and a concomitant increase in dislocation density. Moreover, the potential disparity between the second phase (AlMnFeSi and Mg2Si) and the matrix was diminished. These findings collectively contribute to the enhanced resistance of 6082/AZ31/6082 LMCs to intergranular corrosion and pitting corrosion. However, the accelerated dissolution of the intermediate Mg layer, facilitated by the galvanic corrosion effect during field exposure of the LMCs, resulted in a 4.5-fold increase in corrosion-induced mass loss. Notably, the ultimate tensile strength of the LMCs exhibited insensitivity to field exposure duration, while their plasticity underwent a gradual decline. This comprehensive study elucidates the corrosion behavior and underlying mechanisms of 6082/AZ31/6082 LMCs subjected to a tropical marine atmospheric environment, providing valuable insights for the rational design and development of LMCs with enhanced comprehensive performance

Application of titanium gypsum as raw materials in cement-based self-leveling mortars

There are studies on titanium gypsum (TG) as a cement retarder, cementing material, or the production of lightweight wall materials and roadbed materials, but the application of TG is still limited, the utilization of TG is in the stage of exploration. This work studied the possibility of recycling TG as raw materials for the preparation of cement-based (Sulphate Aluminate Cement and Ordinary Portland Cement) self-leveling mortars. The effects of TG on mechanical strength, fluidity, shrinkage, and wear resistance were carried out. With the help of XRD, TG-DTG, and SEM, the microstructural characteristics were investigated to determine the mechanism of TG. It was concluded that the 1 d compressive and flexural strength reached 9.6 MPa and 3.5 MPa, respectively, and the 28 d compressive and flexural strength reached 4.3 MPa and 17.9 MPa, respectively, when the mass ratio of Sulphate Aluminate Cement (SAC) and Ordinary Portland Cement (OPC) was 7:3, the TG content was 45 %. TG could significantly improve the shrinkage of the mortars to 0.10 %, which was far better than the standard requirements of 0.15 %, but reduce the wear resistance to some extent. The primary component of calcium sulfate dihydrate (CaSO4·2H2O) in TG can further react with the aluminum phase in cement to grow more ettringite, which can make the microstructure denser, thereby improving the strength and the deformation of the cement-based self-leveling mortars

Study on the Optical Properties of Triangular Cavity Absorber for Parabolic Trough Solar Concentrator

A theoretical analytical method for optical properties of cavity absorber was proposed in this paper and the optical design software TracePro was used to analyze the optical properties of triangular cavity absorber. It was found that the optimal optical properties could be achieved with appropriate aperture width, depth-to-width ratio, and offset distance from focus of triangular cavity absorber. Based on the results of orthogonal experiment, the optimized triangular cavity absorber was designed. Results showed that the standard deviation of irradiance and optical efficiency of optimized designed cavity absorber were 30528 W/m2 and 89.23%, respectively. Therefore, this study could offer some valuable references for designing the parabolic trough solar concentrator in the future