Cross-linked polyethylene (PEX) pipes used in hot water supply are required for high mechanical strength and high creep resistance at high temperature. Especially PEX-a pipes which are made by peroxide cross-linking h...Cross-linked polyethylene (PEX) pipes used in hot water supply are required for high mechanical strength and high creep resistance at high temperature. Especially PEX-a pipes which are made by peroxide cross-linking have better performance, such as creep resistance and thermal shock resistance than the pipes made by the other cross-linking method. Because the PEX-a pipes indicate the higher cross-link degree as compared with the other PEX pipes. In this study, the PEX-a pipes which were mixed with several stabilizers were tested to evaluate the effects on cross-link degree and the oxygen induction time. And also they are evaluated with the chlorine aqueous solution by the performance of the long-term hydrostatic pressure test and the long-term hydro dynamic pressure test. As a result, it was found that the combination of antioxidants for PEX-a pipes plays an important role to prolong the oxygen induction time without inhibiting the cross-linking. From the results of the 1H pulsed NMR measurement over the melting point of polyethylene, it was found that each peroxide PEX pipe with different antioxidant combinations indicated the different proportion and crosslink density of cross-linked region, in addition, that these pipes had the effective structure of cross-linking for the hydrostatic and hydrodynamic pressure test with the chlorine aqueous solution. Therefore, it was considered to be useful results for studies of the stricture of cross-linking of polyethylene.展开更多
Chitosan (CS) microparticles with and without cross-linking were prepared by a water-in-oil emulsion solvent diffusion method without any surfactants. Aqueous CS solution and ethyl ace- tate were used as water and oil...Chitosan (CS) microparticles with and without cross-linking were prepared by a water-in-oil emulsion solvent diffusion method without any surfactants. Aqueous CS solution and ethyl ace- tate were used as water and oil phases, respectively. Genipin was used as a cross-linker. Influ- ences of genipin ratios and cross-linking times on CS microparticle characteristics were investigated. Non-cross-linked and cross-linked CS microparticles were spherical in shape and rough in surface. Microparticle matrices showed porous structures. Surface roughness, mean par- ticle sizes and bulk density of CS microparticles increased and their dissolutions in acetic acid solution decreased when genipin ratio and cross- linking time increased.展开更多
The macroporous anion exchangers with long-chained cross-linking agents were investigated for the tungsten recovery from salt solutions. The physical-chemical characteristics of these sorbents were studied by means o...The macroporous anion exchangers with long-chained cross-linking agents were investigated for the tungsten recovery from salt solutions. The physical-chemical characteristics of these sorbents were studied by means of sorption-desorption experiment aswell as electron and IR-spectroscopy. The anion exchangers on the basis of macroporous copolymers of methylacrylate and divinyl-ester of diethyleneglycol or tetravinyl-ester of pentaerythritol possess the exchange capacity to tungsten 2--5 times greater than the porous anion exchangers on the basis of styrene and divinylbenzene, therefore they can be used for selective tungsten recovery from comulex salt solutions.展开更多
Network information mining is the study of the network topology,which may answer a large number of applicationbased questions towards the structural evolution and the function of a real system.The question can be rela...Network information mining is the study of the network topology,which may answer a large number of applicationbased questions towards the structural evolution and the function of a real system.The question can be related to how the real system evolves or how individuals interact with each other in social networks.Although the evolution of the real system may seem to be found regularly,capturing patterns on the whole process of evolution is not trivial.Link prediction is one of the most important technologies in network information mining,which can help us understand the evolution mechanism of real-life network.Link prediction aims to uncover missing links or quantify the likelihood of the emergence of nonexistent links from known network structures.Currently,widely existing methods of link prediction almost focus on short-path networks that usually have a myriad of close triangular structures.However,these algorithms on highly sparse or longpath networks have poor performance.Here,we propose a new index that is associated with the principles of structural equivalence and shortest path length(SESPL)to estimate the likelihood of link existence in long-path networks.Through a test of 548 real networks,we find that SESPL is more effective and efficient than other similarity-based predictors in long-path networks.Meanwhile,we also exploit the performance of SESPL predictor and of embedding-based approaches via machine learning techniques.The results show that the performance of SESPL can achieve a gain of 44.09%over GraphWave and 7.93%over Node2vec.Finally,according to the matrix of maximal information coefficient(MIC)between all the similarity-based predictors,SESPL is a new independent feature in the space of traditional similarity features.展开更多
Link prediction is used to complete the knowledge graph.Convolu-tional neural network models are commonly used for link prediction tasks,but they only consider the direct relations between entity pairs,ignoring the se...Link prediction is used to complete the knowledge graph.Convolu-tional neural network models are commonly used for link prediction tasks,but they only consider the direct relations between entity pairs,ignoring the semantic information contained in the relation paths.In addition,the embedding dimension of the relation is generally larger than that of the entity in the ConvR model,which blocks the progress of downstream tasks.If we reduce the embedding dimension of the relation,the performance will be greatly degraded.This paper proposes a convolutional model PITri-R-ConvR based on triangular structure relational infer-ence.The model uses relational path inference to capture semantic information,while using a triangular structure to ensure the reliability and computational effi-ciency of relational inference.In addition,the decoder R-ConvR improves the initial embedding of the ConvR model,which solves the problems of the ConvR model and significantly improves the prediction performance.Finally,this paper conducts sufficient experiments in multiple datasets to verify the superiority of the model and the rationality of each module.展开更多
Alzheimer’s disease is a primary age-related neurodegenerative disorder that can result in impaired cognitive and memory functions.Although connections between changes in brain networks of Alzheimer’s disease patien...Alzheimer’s disease is a primary age-related neurodegenerative disorder that can result in impaired cognitive and memory functions.Although connections between changes in brain networks of Alzheimer’s disease patients have been established,the mechanisms that drive these alterations remain incompletely understood.This study,which was conducted in 2018 at Northeastern University in China,included data from 97 participants of the Alzheimer’s Disease Neuroimaging Initiative(ADNI)dataset covering genetics,imaging,and clinical data.All participants were divided into two groups:normal control(n=52;20 males and 32 females;mean age 73.90±4.72 years)and Alzheimer’s disease(n=45,23 males and 22 females;mean age 74.85±5.66).To uncover the wiring mechanisms that shaped changes in the topology of human brain networks of Alzheimer’s disease patients,we proposed a local naive Bayes brain network model based on graph theory.Our results showed that the proposed model provided an excellent fit to observe networks in all properties examined,including clustering coefficient,modularity,characteristic path length,network efficiency,betweenness,and degree distribution compared with empirical methods.This proposed model simulated the wiring changes in human brain networks between controls and Alzheimer’s disease patients.Our results demonstrate its utility in understanding relationships between brain tissue structure and cognitive or behavioral functions.The ADNI was performed in accordance with the Good Clinical Practice guidelines,US 21 CFR Part 50-Protection of Human Subjects,and Part 56-Institutional Review Boards(IRBs)/Research Good Clinical Practice guidelines Institutional Review Boards(IRBs)/Research Ethics Boards(REBs).展开更多
1 Introduction Immobilization of homogeneous catalysts onto polymer supports through covalent attachment has received wide attention because these materials offer advantage features of heterogeneous catalysis to homog...1 Introduction Immobilization of homogeneous catalysts onto polymer supports through covalent attachment has received wide attention because these materials offer advantage features of heterogeneous catalysis to homogeneous systems.The polymer-supported catalysts enhance their thermal stability,selectivity,recyclability and easy separation from reaction products leading to the operationally flexible[1-2].Such behaviour prompted us to know the effect of pore structures of polymer supporters on catalytic ...展开更多
Wireless Multimedia Sensor Networks (WMSNs), is a network of sensors, which are limited in terms of memory, computing, bandwidth, and battery lifetime. Multimedia transmission over WSN requires certain QoS guarantees ...Wireless Multimedia Sensor Networks (WMSNs), is a network of sensors, which are limited in terms of memory, computing, bandwidth, and battery lifetime. Multimedia transmission over WSN requires certain QoS guarantees such as huge amount of bandwidth, strict delay and lower loss ratio that makes transmitting multimedia is a complicated task. However, adopting cross-layer approach in WMSNs improves quality of service of WSN under different environmental conditions. In this work, an energy efficient and QoS aware framework for transmitting multimedia content over WSN (EQWSN) is presented, where packet, queue and path scheduling were introduced. It adapts the application layer parameter of video encoder to current wireless channel state, and drops less important packets in case of network congestion according to packet type. Finally, the path scheduling differentiates packets types/priority and route them through different paths with different QoS considering network lifetime. Simulation results show that the new scheme EQWSN transmits video quality with QoS guarantees in addition to prolonging network lifetime.展开更多
Problem: A common assumption is that students prefer to select their friends for group-work. The prime goal of this study was to understand the impact of two group selection methods on how students from diverse cultur...Problem: A common assumption is that students prefer to select their friends for group-work. The prime goal of this study was to understand the impact of two group selection methods on how students from diverse cultural backgrounds build learning and work relations. Method: Social Network Analysis in a pre-post test manner in a quasi-experimental design of 81 vs. 70 third-year students. Solution: In this study, we “disrupted” this group selection process after Day 1 by balancing students from different parts of the social network together. In one condition the students were “balanced” into groups by staff to encourage structural hole formation, and in the other condition students were allowed to self-select their group members to encourage network closure. Results: Students in the self-selected condition primarily selected their friends from a similar cultural background. In both conditions the learning networks after 11 weeks were primarily predicted by the group allocation and initial friendships. However, students in the balanced condition developed more cross-cultural learning links. These results indicate that teachers can actively intervene in the cross-cultural dynamics in- and outside the classroom.展开更多
文摘Cross-linked polyethylene (PEX) pipes used in hot water supply are required for high mechanical strength and high creep resistance at high temperature. Especially PEX-a pipes which are made by peroxide cross-linking have better performance, such as creep resistance and thermal shock resistance than the pipes made by the other cross-linking method. Because the PEX-a pipes indicate the higher cross-link degree as compared with the other PEX pipes. In this study, the PEX-a pipes which were mixed with several stabilizers were tested to evaluate the effects on cross-link degree and the oxygen induction time. And also they are evaluated with the chlorine aqueous solution by the performance of the long-term hydrostatic pressure test and the long-term hydro dynamic pressure test. As a result, it was found that the combination of antioxidants for PEX-a pipes plays an important role to prolong the oxygen induction time without inhibiting the cross-linking. From the results of the 1H pulsed NMR measurement over the melting point of polyethylene, it was found that each peroxide PEX pipe with different antioxidant combinations indicated the different proportion and crosslink density of cross-linked region, in addition, that these pipes had the effective structure of cross-linking for the hydrostatic and hydrodynamic pressure test with the chlorine aqueous solution. Therefore, it was considered to be useful results for studies of the stricture of cross-linking of polyethylene.
文摘Chitosan (CS) microparticles with and without cross-linking were prepared by a water-in-oil emulsion solvent diffusion method without any surfactants. Aqueous CS solution and ethyl ace- tate were used as water and oil phases, respectively. Genipin was used as a cross-linker. Influ- ences of genipin ratios and cross-linking times on CS microparticle characteristics were investigated. Non-cross-linked and cross-linked CS microparticles were spherical in shape and rough in surface. Microparticle matrices showed porous structures. Surface roughness, mean par- ticle sizes and bulk density of CS microparticles increased and their dissolutions in acetic acid solution decreased when genipin ratio and cross- linking time increased.
文摘The macroporous anion exchangers with long-chained cross-linking agents were investigated for the tungsten recovery from salt solutions. The physical-chemical characteristics of these sorbents were studied by means of sorption-desorption experiment aswell as electron and IR-spectroscopy. The anion exchangers on the basis of macroporous copolymers of methylacrylate and divinyl-ester of diethyleneglycol or tetravinyl-ester of pentaerythritol possess the exchange capacity to tungsten 2--5 times greater than the porous anion exchangers on the basis of styrene and divinylbenzene, therefore they can be used for selective tungsten recovery from comulex salt solutions.
基金supported by the National Natural Science Foundation of China(Grant Nos.61773091 and 62173065)the Industry-University-Research Innovation Fund for Chinese Universities(Grant No.2021ALA03016)+2 种基金the Fund for University Innovation Research Group of Chongqing(Grant No.CXQT21005)the National Social Science Foundation of China(Grant No.20CTQ029)the Fundamental Research Funds for the Central Universities(Grant No.SWU119062).
文摘Network information mining is the study of the network topology,which may answer a large number of applicationbased questions towards the structural evolution and the function of a real system.The question can be related to how the real system evolves or how individuals interact with each other in social networks.Although the evolution of the real system may seem to be found regularly,capturing patterns on the whole process of evolution is not trivial.Link prediction is one of the most important technologies in network information mining,which can help us understand the evolution mechanism of real-life network.Link prediction aims to uncover missing links or quantify the likelihood of the emergence of nonexistent links from known network structures.Currently,widely existing methods of link prediction almost focus on short-path networks that usually have a myriad of close triangular structures.However,these algorithms on highly sparse or longpath networks have poor performance.Here,we propose a new index that is associated with the principles of structural equivalence and shortest path length(SESPL)to estimate the likelihood of link existence in long-path networks.Through a test of 548 real networks,we find that SESPL is more effective and efficient than other similarity-based predictors in long-path networks.Meanwhile,we also exploit the performance of SESPL predictor and of embedding-based approaches via machine learning techniques.The results show that the performance of SESPL can achieve a gain of 44.09%over GraphWave and 7.93%over Node2vec.Finally,according to the matrix of maximal information coefficient(MIC)between all the similarity-based predictors,SESPL is a new independent feature in the space of traditional similarity features.
基金This work was supported by the National Key R&D Program of China under Grant No.20201710200.
文摘Link prediction is used to complete the knowledge graph.Convolu-tional neural network models are commonly used for link prediction tasks,but they only consider the direct relations between entity pairs,ignoring the semantic information contained in the relation paths.In addition,the embedding dimension of the relation is generally larger than that of the entity in the ConvR model,which blocks the progress of downstream tasks.If we reduce the embedding dimension of the relation,the performance will be greatly degraded.This paper proposes a convolutional model PITri-R-ConvR based on triangular structure relational infer-ence.The model uses relational path inference to capture semantic information,while using a triangular structure to ensure the reliability and computational effi-ciency of relational inference.In addition,the decoder R-ConvR improves the initial embedding of the ConvR model,which solves the problems of the ConvR model and significantly improves the prediction performance.Finally,this paper conducts sufficient experiments in multiple datasets to verify the superiority of the model and the rationality of each module.
基金Fundamental Research Funds for the Central Universities in China,No.N161608001 and No.N171903002
文摘Alzheimer’s disease is a primary age-related neurodegenerative disorder that can result in impaired cognitive and memory functions.Although connections between changes in brain networks of Alzheimer’s disease patients have been established,the mechanisms that drive these alterations remain incompletely understood.This study,which was conducted in 2018 at Northeastern University in China,included data from 97 participants of the Alzheimer’s Disease Neuroimaging Initiative(ADNI)dataset covering genetics,imaging,and clinical data.All participants were divided into two groups:normal control(n=52;20 males and 32 females;mean age 73.90±4.72 years)and Alzheimer’s disease(n=45,23 males and 22 females;mean age 74.85±5.66).To uncover the wiring mechanisms that shaped changes in the topology of human brain networks of Alzheimer’s disease patients,we proposed a local naive Bayes brain network model based on graph theory.Our results showed that the proposed model provided an excellent fit to observe networks in all properties examined,including clustering coefficient,modularity,characteristic path length,network efficiency,betweenness,and degree distribution compared with empirical methods.This proposed model simulated the wiring changes in human brain networks between controls and Alzheimer’s disease patients.Our results demonstrate its utility in understanding relationships between brain tissue structure and cognitive or behavioral functions.The ADNI was performed in accordance with the Good Clinical Practice guidelines,US 21 CFR Part 50-Protection of Human Subjects,and Part 56-Institutional Review Boards(IRBs)/Research Good Clinical Practice guidelines Institutional Review Boards(IRBs)/Research Ethics Boards(REBs).
文摘1 Introduction Immobilization of homogeneous catalysts onto polymer supports through covalent attachment has received wide attention because these materials offer advantage features of heterogeneous catalysis to homogeneous systems.The polymer-supported catalysts enhance their thermal stability,selectivity,recyclability and easy separation from reaction products leading to the operationally flexible[1-2].Such behaviour prompted us to know the effect of pore structures of polymer supporters on catalytic ...
文摘Wireless Multimedia Sensor Networks (WMSNs), is a network of sensors, which are limited in terms of memory, computing, bandwidth, and battery lifetime. Multimedia transmission over WSN requires certain QoS guarantees such as huge amount of bandwidth, strict delay and lower loss ratio that makes transmitting multimedia is a complicated task. However, adopting cross-layer approach in WMSNs improves quality of service of WSN under different environmental conditions. In this work, an energy efficient and QoS aware framework for transmitting multimedia content over WSN (EQWSN) is presented, where packet, queue and path scheduling were introduced. It adapts the application layer parameter of video encoder to current wireless channel state, and drops less important packets in case of network congestion according to packet type. Finally, the path scheduling differentiates packets types/priority and route them through different paths with different QoS considering network lifetime. Simulation results show that the new scheme EQWSN transmits video quality with QoS guarantees in addition to prolonging network lifetime.
文摘Problem: A common assumption is that students prefer to select their friends for group-work. The prime goal of this study was to understand the impact of two group selection methods on how students from diverse cultural backgrounds build learning and work relations. Method: Social Network Analysis in a pre-post test manner in a quasi-experimental design of 81 vs. 70 third-year students. Solution: In this study, we “disrupted” this group selection process after Day 1 by balancing students from different parts of the social network together. In one condition the students were “balanced” into groups by staff to encourage structural hole formation, and in the other condition students were allowed to self-select their group members to encourage network closure. Results: Students in the self-selected condition primarily selected their friends from a similar cultural background. In both conditions the learning networks after 11 weeks were primarily predicted by the group allocation and initial friendships. However, students in the balanced condition developed more cross-cultural learning links. These results indicate that teachers can actively intervene in the cross-cultural dynamics in- and outside the classroom.
