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16,990 result(s) for "Xu, Fei-fei"
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Smart library personalized resource proactive recommendation system integrating user profiling and knowledge graphs
The resource recommendation service of smart libraries is facing a dual dilemma of imprecise perception of user needs and passivity in recommendation patterns. Existing approaches mostly adopt classical paradigms of collaborative filtering or content-based filtering, exhibiting notable limitations in the following aspects: user profiles primarily rely on single-dimensional borrowing or retrieval behavioral data without integrating academic characteristics such as disciplinary backgrounds and research stages; knowledge graphs are mostly confined to collection metadata without embedding disciplinary ontologies and citation networks, limiting the mining of cross-domain resource semantic associations; and recommendation mechanisms lack context-aware proactive push capabilities, with recommendation timing being disconnected from readers’ research rhythms and interest evolution trajectories. To address these issues, this paper proposes a smart library personalized resource proactive recommendation system that integrates multi-dimensional user profiling with a disciplinary knowledge graph. At the user modeling level, the system incorporates readers’ borrowing records, retrieval logs, disciplinary backgrounds, and temporal behavioral patterns, employing a multi-head attention mechanism to achieve adaptive weighted fusion of multi-source heterogeneous features, and capturing the dynamic evolution trajectory of user interests through a gated recurrent unit. At the knowledge representation level, a library resource knowledge graph that fuses collection metadata, disciplinary ontologies, and citation networks is constructed, with a graph attention network employed for embedding learning of higher-order semantic relationships. Compared with GCN, GAT can adaptively assign differentiated aggregation weights to different neighbor nodes, making it more suitable for the library knowledge graph where different relation types contribute unevenly to recommendation. At the recommendation strategy level, a context-aware proactive recommendation mechanism based on interest drift detection is designed, which determines the optimal push timing by monitoring temporal changes in user profiles. The interest drift threshold is optimized through grid search on the validation set, and three types of contextual signals — access context, research stage, and interest drift — are fused through a gated aggregation mechanism to jointly trigger proactive push. Experimental results on a university library dataset demonstrate that the proposed method achieves 16.02% and 11.64% on Recall@10 and NDCG@10, respectively, representing improvements of 4.87% and 5.23% over the best-performing baseline methods. The push acceptance rate of proactive recommendations reaches 38.9%, significantly outperforming the random push strategy. Ablation experiments validate the effectiveness of each core module, with the knowledge graph module making the most prominent contribution to recommendation accuracy, primarily because it mines cross-domain resource correlations through disciplinary ontologies and citation networks that traditional metadata-based methods cannot capture.
Glycyrrhizin mitigates radiation‐induced acute lung injury by inhibiting the HMGB1/TLR4 signalling pathway
Radiation‐induced lung injury (RILI) is the major complication of thoracic radiation therapy, and no effective treatment is available. This study explored the role of high‐mobility group box 1 (HMGB1) in acute RILI and the therapeutic effect of glycyrrhizin, an inhibitor of HMGB1, on RILI. C57BL/6 mice received a 20 Gy dose of X‐ray radiation to the whole thorax with or without administration of glycyrrhizin. Severe lung inflammation was present 12 weeks after irradiation, although only a mild change was noted at 2 weeks and could be alleviated by administration of glycyrrhizin. Glycyrrhizin decreased the plasma concentrations of HMGB1 and sRAGE as well as TNF‐α, IL‐1β and IL‐6 levels in the bronchoalveolar lavage fluid (BALF). The expression of RAGE was decreased while that of TLR4 was significantly increased at 12 weeks, but not 2 weeks, after irradiation in mouse lung tissue. In vitro, the expression of TLR4 increased in RAW 264.7 cells after conditioning with the supernatant from the irradiated MLE‐12 cells containing HMGB1 but showed no change when conditioned medium without HMGB1 was used. However, conditioned culture had no effect on RAGE expression in RAW 264.7 cells. Glycyrrhizin also inhibited the related downstream transcription factors of HMGB/TLR4, such as NF‐κB, JNK and ERK1/2, in lung tissue and RAW 264.7 cells when TLR4 was activated. In conclusion, the HMGB1/TLR4 pathway mediates RILI and can be mitigated by glycyrrhizin.
Distributed quantum phase estimation with entangled photons
Distributed quantum metrology can enhance the sensitivity for sensing spatially distributed parameters beyond the classical limits. Here we demonstrate distributed quantum phase estimation with discrete variables to achieve Heisenberg limit phase measurements. Based on parallel entanglement in modes and particles, we demonstrate distributed quantum sensing for both individual phase shifts and an averaged phase shift, with an error reduction up to 1.4 dB and 2.7 dB below the shot-noise limit. Furthermore, we demonstrate a combined strategy with parallel mode entanglement and multiple passes of the phase shifter in each mode. In particular, our experiment uses six entangled photons with each photon passing the phase shifter up to six times, and achieves a total number of photon passes N = 21 at an error reduction up to 4.7 dB below the shot-noise limit. Our research provides a faithful verification of the benefit of entanglement and coherence for distributed quantum sensing in general quantum networks.Distributed quantum metrology is demonstrated for both individual and averaged phase shifts by using discrete-variable entangled photons. An error reduction of 4.7 dB below the shot-noise limit is achieved when a total number of photon passes is 21.
Methicillin-resistant Staphylococcus aureus alters cell wall glycosylation to evade immunity
Methicillin-resistant Staphylococcus aureus (MRSA) is a frequent cause of difficult-to-treat, often fatal infections in humans 1 , 2 . Most humans have antibodies against S. aureus , but these are highly variable and often not protective in immunocompromised patients 3 . Previous vaccine development programs have not been successful 4 . A large percentage of human antibodies against S. aureus target wall teichoic acid (WTA), a ribitol-phosphate (RboP) surface polymer modified with N -acetylglucosamine (GlcNAc) 5 , 6 . It is currently unknown whether the immune evasion capacities of MRSA are due to variation of dominant surface epitopes such as those associated with WTA. Here we show that a considerable proportion of the prominent healthcare-associated and livestock-associated MRSA clones CC5 and CC398, respectively, contain prophages that encode an alternative WTA glycosyltransferase. This enzyme, TarP, transfers GlcNAc to a different hydroxyl group of the WTA RboP than the standard enzyme TarS 7 , with important consequences for immune recognition. TarP-glycosylated WTA elicits 7.5–40-fold lower levels of immunoglobulin G in mice than TarS-modified WTA. Consistent with this, human sera contained only low levels of antibodies against TarP-modified WTA. Notably, mice immunized with TarS-modified WTA were not protected against infection with tarP -expressing MRSA, indicating that TarP is crucial for the capacity of S. aureus to evade host defences. High-resolution structural analyses of TarP bound to WTA components and uridine diphosphate GlcNAc (UDP-GlcNAc) explain the mechanism of altered RboP glycosylation and form a template for targeted inhibition of TarP. Our study reveals an immune evasion strategy of S. aureus based on averting the immunogenicity of its dominant glycoantigen WTA. These results will help with the identification of invariant S. aureus vaccine antigens and may enable the development of TarP inhibitors as a new strategy for rendering MRSA susceptible to human host defences. Strains of methicillin-resistant Staphylococcus aureus use a prophage-encoded glycosyltransferase to alter the glycosylation of their wall teichoic acid and thereby evade antibody-mediated immune responses.
Roles of the PI3K/AKT/mTOR signalling pathways in neurodegenerative diseases and tumours
The PI3 K/AKT/mTOR signalling pathway plays an important role in the regulation of signal transduction and biological processes such as cell proliferation, apoptosis, metabolism and angiogenesis. Compared with those of other signalling pathways, the components of the PI3K/AKT/mTOR signalling pathway are complicated. The regulatory mechanisms and biological functions of the PI3K/AKT/mTOR signalling pathway are important in many human diseases, including ischaemic brain injury, neurodegenerative diseases, and tumours. PI3K/AKT/mTOR signalling pathway inhibitors include single-component and dual inhibitors. Numerous PI3K inhibitors have exhibited good results in preclinical studies, and some have been clinically tested in haematologic malignancies and solid tumours. In this review, we briefly summarize the results of research on the PI3K/AKT/mTOR pathway and discuss the structural composition, activation, communication processes, regulatory mechanisms and biological functions of the PI3K/AKT/mTOR signalling pathway in the pathogenesis of neurodegenerative diseases and tumours.
Unravelling the structure of glycosyl cations via cold-ion infrared spectroscopy
Glycosyl cations are the key intermediates during the glycosylation reaction that covalently links building blocks during the synthetic assembly of carbohydrates. The exact structure of these ions remained elusive due to their transient and short-lived nature. Structural insights into the intermediate would improve our understanding of the reaction mechanism of glycosidic bond formation. Here, we report an in-depth structural analysis of glycosyl cations using a combination of cold-ion infrared spectroscopy and first-principles theory. Participating C2 protective groups form indeed a covalent bond with the anomeric carbon that leads to C1-bridged acetoxonium-type structures. The resulting bicyclic structure strongly distorts the ring, which leads to a unique conformation for each individual monosaccharide. This gain in mechanistic understanding fundamentally impacts glycosynthesis and will allow to tailor building blocks and reaction conditions in the future. Glycosyl cations are key intermediates in glycosylation reactions, but their structure has remained elusive due to their transient nature. Here, the authors perform an in-depth structural analysis and report that C2-participating protective groups induce acetoxonium cations with distinct ring conformations.
A Bio‐Based Supramolecular Adhesive: Ultra‐High Adhesion Strengths at both Ambient and Cryogenic Temperatures and Excellent Multi‐Reusability
Developing high‐performance and reusable adhesives from renewable feedstocks is of significance to sustainable development, yet it still remains a formidable task. Herein, castor oil, melevodopa, and iron ions are used as building blocks to construct a novel bio‐based supramolecular adhesive (BSA) with outstanding adhesion performances. It is prepared through partial coordination between melevodopa functionalized castor oil and Fe3+ ions. Noncovalent interactions between adherends and the catechol unit from melevodopa contribute to reinforcing adhesion, and the metal‐ligand coordination between catechol and Fe3+ ions is utilized to strengthen cohesion. By combining strong adhesion and tough cohesion, the prepared BSA achieves an adhesion strength of 14.6 MPa at ambient temperature, a record‐high value among reported bio‐based adhesives as well as supramolecular adhesives to the best of knowledge. It also outperforms those adhesives at cryogenic temperature, realizing another record‐high adhesion strength of 9.5 MPa at −196 °C. In addition, the BSA displays excellent multi‐reusability with more than 87% of the original adhesion strength remaining even after reuse for ten times. It is highly anticipated that this line of research will provide a new insight into designing bio‐based adhesives with outstanding adhesion performances and excellent multi‐reusability. An ultra‐strong and multi‐reusable bio‐based adhesive is successfully constructed by utilizing castor oil, melevodopa, and iron ions as building blocks. By combining strong adhesion with tough cohesion, it achieves record‐high adhesion strengths of 14.6 MPa at ambient temperature and 9.5 MPa at −196 °C. What's more, it exhibits excellent multi‐reusability of ten times with over 87% adhesion strength remaining.
Epidemiology of esophageal cancer in 2020 and projections to 2030 and 2040
Esophageal cancer is a familiar malignancy with high incidence and mortality, and the overall prognosis is poor. The numbers of cases of and deaths from esophageal cancer have risen rapidly in recent decades. It is one of the most malignant cancers, with more than 0.6 million new cases and 0.54 million deaths worldwide in 2020. Here, we present the global epidemiology of esophageal cancer in 2020 and projections to 2030 and 2040 at different geographical levels of continents, regions and countries, and analyze them by gender, race, geographic region and human development index. We summarize the prospects for the esophageal cancer burden and risk factors in different areas, which will be useful for global esophageal cancer clinical therapy and cancer control planning. Esophageal cancer is one of the most malignant cancers, with more than 0.6 million new cases of esophageal cancer and 0.54 million deaths worldwide in 2020. In current review, we present the global epidemiology of esophageal cancer in 2020 and projections to two decades later at different levels of continents, regions and countries and analyze them in gender, race, geographic region, and human development index. Graph showed global and top 3 countries with the highest incident cases of esophageal cancer in 2020 and projections to 2030 and 2040.
Closed-loop chemical recycling of cross-linked polymeric materials based on reversible amidation chemistry
Closed-loop chemical recycling provides a solution to the end-of-use problem of synthetic polymers. However, it remains a major challenge to design dynamic bonds, capable of effective bonding and reversible cleaving, for preparing chemically recyclable cross-linked polymers. Herein, we report a dynamic maleic acid tertiary amide bond based upon reversible amidation reaction between maleic anhydrides and secondary amines. This dynamic bond allows for the construction of polymer networks with tailorable and robust mechanical properties, covering strong elastomers with a tensile strength of 22.3 MPa and rigid plastics with a yield strength of 38.3 MPa. Impressively, these robust polymeric materials can be completely depolymerized in an acidic aqueous solution at ambient temperature, leading to efficient monomer recovery with >94% separation yields. Meanwhile, the recovered monomers can be used to remanufacture cross-linked polymeric materials without losing their original mechanical performance. This work unveils a general approach to design polymer networks with tunable mechanical performance and closed-loop recyclability, which will open a new avenue for sustainable polymeric materials. Closed-loop chemical recycling provides a solution to the end-of-use problem of synthetic polymers but the design of dynamic bonds for preparing chemically recyclable cross-linked polymers remains challenging. Here, the authors report a dynamic reversible amidation reaction between maleic anhydrides and secondary amines.
Construction of a mammalian embryo model from stem cells organized by a morphogen signalling centre
Generating properly differentiated embryonic structures in vitro from pluripotent stem cells remains a challenge. Here we show that instruction of aggregates of mouse embryonic stem cells with an experimentally engineered morphogen signalling centre, that functions as an organizer, results in the development of embryo-like entities (embryoids). In situ hybridization, immunolabelling, cell tracking and transcriptomic analyses show that these embryoids form the three germ layers through a gastrulation process and that they exhibit a wide range of developmental structures, highly similar to neurula-stage mouse embryos. Embryoids are organized around an axial chordamesoderm, with a dorsal neural plate that displays histological properties similar to the murine embryo neuroepithelium and that folds into a neural tube patterned antero-posteriorly from the posterior midbrain to the tip of the tail. Lateral to the chordamesoderm, embryoids display somitic and intermediate mesoderm, with beating cardiac tissue anteriorly and formation of a vasculature network. Ventrally, embryoids differentiate a primitive gut tube, which is patterned both antero-posteriorly and dorso-ventrally. Altogether, embryoids provide an in vitro model of mammalian embryo that displays extensive development of germ layer derivatives and that promises to be a powerful tool for in vitro studies and disease modelling. Following instruction by a morphogen secreting centre, aggregates of mouse embryonic stem cells develop into embryo-like structures organized around an axial mesoderm, which show extensive characteristics of a neurula-stage mouse embryo, with antero-posterior and dorso-ventral patterning of germ layer derivatives.