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

Preparation of Well-Defined Propargyl-Terminated Tetra-Arm Poly(N-isopropylacrylamide)s and Their Click Hydrogels Crosslinked with β-cyclodextrin

As an important class of reversible deactivation radical polymerization (RDRP), reversible addition fragmentation chain transfer (RAFT) polymerization has attracted great attention attributed to its facile and flexible features to prepare well-defined polymers with different complex structures. In addition, the combination of RAFT with click chemistry provides more effective strategies to fabricate advanced functional materials. In this work, a series of temperature responsive tetra-arm telechelic poly(N-isopropylacrylamide)s (PNIPAs) with propargyl end groups were prepared for the first time through RAFT and subsequent aminolysis/Michael addition modification. The temperature sensitivities of their aqueous solutions were researched via turbidity measurement. It was found that the phase transition temperature of obtained PNIPAs increased with their molecular weights ascribed to their distinctions in the hydrophobic/hydrophilic balance. Subsequently, β-cyclodextrin (β-CD) functionalized with azide moieties was used to crosslink the prepared propargyl-terminated tetra-arm PNIPAs through click chemistry, fabricating corresponding hydrogels with thermoresponse. Similar to their precursors, the hydrogels demonstrated the same dependence of volume phase transition temperature (VPTT) on their molecular weights. In addition, the incorporation of β-CD and the residual groups besides crosslinking may provide a platform for imparting additional functions such as inclusion and adsorption as well as further functionalization

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

Effects of Variations in Soil Moisture and Phosphorus Concentrations on the Diversity of the Arbuscular Mycorrhizal Fungi Community in an Agricultural Ecosystem

In farmland ecosystems, phosphorus and water have crucial roles. To elucidate the effects of phosphorus concentration and water management on arbuscular mycorrhizal fungi (AMF), field experiments were conducted in a farmland ecosystem (China). We examined the effects of different treatments, including drought and normal phosphorus, normal water and normal phosphorus, drought and low phosphorus, and normal water and low phosphorus, on the AM fungal biomass, diversity, and community. Results showed great differences in the AMF under different water and phosphorus concentrations. When under a suitable drought treatment, the AMF became more abundant and more conducive to plant growth. The abundance of AMF varied with different phosphorus treatments, and the abundance of AMF in low-phosphorus treatments was higher, which is more suitable for plant growth. In conclusion, as water and phosphorus concentrations change, the community structure of AMF constantly changes. Only under the appropriate water and phosphorus concentration processing can AMF play its role well. Understanding the influence of different phosphorus concentrations and the moisture contents of AMF can play a role in the agricultural production of AMF, and it can also provide improved theoretical support

List of primers used for DNA amplification and sequencing.

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