Disentangled Graph Social Recommendation

Social recommender systems have drawn a lot of attention in many online web services, because of the incorporation of social information between users in improving recommendation results. Despite the significant progress made by existing solutions, we argue that current methods fall short in two limitations: (1) Existing social-aware recommendation models only consider collaborative similarity between items, how to incorporate item-wise semantic relatedness is less explored in current recommendation paradigms. (2) Current social recommender systems neglect the entanglement of the latent factors over heterogeneous relations (e.g., social connections, user-item interactions). Learning the disentangled representations with relation heterogeneity poses great challenge for social recommendation. In this work, we design a Disentangled Graph Neural Network (DGNN) with the integration of latent memory units, which empowers DGNN to maintain factorized representations for heterogeneous types of user and item connections. Additionally, we devise new memory-augmented message propagation and aggregation schemes under the graph neural architecture, allowing us to recursively distill semantic relatedness into the representations of users and items in a fully automatic manner. Extensive experiments on three benchmark datasets verify the effectiveness of our model by achieving great improvement over state-of-the-art recommendation techniques. The source code is publicly available at: https://github.com/HKUDS/DGNN.Comment: Accepted by IEEE ICDE 202

Mechanisms of mercury with typical organics in the incineration of sewage sludge: A computational investigation

In this work, using quantum chemistry methods the reactions of Hg and HgO with six organics including methane (CH), benzene (CH), methanol (CHOH), formaldehyde (HCHO), formic acid (HCOOH) and phenol (CHOH) in sludge incineration were investigated. The computational result indicates that Hg reacts with six organics via insertion mechanism to form CHHgH, CHOHgH, CHHgOH, HHgCHOH, HCOHgH, HCHgO, HHgCOOH, HOCHHgO, HCOOHgH, HCOHgOH, CHHgH, CHOHgH, CHHgOH, and m-, o-, p-HHgCHOH. However, all barriers involved are extremely high and all products are rather unstable, therefore, Hg will be discharged as elements into fuel gas. With extra oxygen supplied Hg could be oxidized to HgO firstly; subsequently, CHOHgOH, HCOHgOH, HOCOHgOH, CHHgOH and o-HOHgCH-OH were formed when HgO reacts with above above organics. The corresponding barriers are lower and all products are much more stable, indicating these Hg-contained organic compounds would be generated readily in incineration of sludge. Therefore it is presumed that in presence of oxygen Hg is more active to react with organics in sludge incineration

Molecular Phylogeny of the Cliff Ferns (Woodsiaceae: Polypodiales) with a Proposed Infrageneric Classification

<div><p>The cliff fern family Woodsiaceae has experienced frequent taxonomic changes at the familial and generic ranks since its establishment. The bulk of its species were placed in <i>Woodsia</i>, while <i>Cheilanthopsis</i>, <i>Hymenocystis</i>, <i>Physematium</i>, and <i>Protowoodsia</i> are segregates recognized by some authors. Phylogenetic relationships among the genera of Woodsiaceae remain unclear because of the extreme morphological diversity and inadequate taxon sampling in phylogenetic studies to date. In this study, we carry out comprehensive phylogenetic analyses of Woodsiaceae using molecular evidence from four chloroplast DNA markers (<i>atp</i>A, <i>mat</i>K, <i>rbc</i>L and <i>trn</i>L–F) and covering over half the currently recognized species. Our results show three main clades in Woodsiaceae corresponding to <i>Physematium</i> (clade I), <i>Cheilanthopsis</i>–<i>Protowoodsia</i> (clade II) and <i>Woodsia</i> s.s. (clade III). In the interest of preserving monophyly and taxonomic stability, a broadly defined <i>Woodsia</i> including the other segregates is proposed, which is characterized by the distinctive indument and inferior indusia. Therefore, we present a new subgeneric classification of the redefined <i>Woodsia</i> based on phylogenetic and ancestral state reconstructions to better reflect the morphological variation, geographic distribution pattern, and evolutionary history of the genus. Our analyses of the cytological character evolution support multiple aneuploidy events that have resulted in the reduction of chromosome base number from 41 to 33, 37, 38, 39 and 40 during the evolutionary history of the cliff ferns.</p></div

List of primers used for DNA amplification and sequencing.

<p>List of primers used for DNA amplification and sequencing.</p