A time sequence analysis on the informal information flow mechanism of microblogging

Microblog is a new Internet featured product, which has seen a rapid development in recent years. Researchers from different countries are making various technical analyses on microblogging applications. In this study, through using the natural language processing(NLP) and data mining, we analyzed the information content transmitted via a microblog, users' social networks and their interactions, and carried out an empirical analysis on the dissemination process of one particular piece of information via Sina Weibo.Based on the result of these analyses, we attempt to develop a better understanding about the rule and mechanism of the informal information flow in microblogging.

Designed assembly of heterometallic cluster organic frameworks based on Th_6 cluster

Four novel compounds based on hexanuclear thorium cluster were synthesized and characterized.Compound 1[Th_(6)(HPy C)_(8)(HCOO)_(4)]is formed by replacing formate ligands of preassembled thorium cluster[Th_(6)O_(4)(OH)_(4)(H_(2)O)_(6)(HCOO)_(12)]with eight H_(2)Py C(4-pyrazolecarboxylic acid)under solvothermal conditions.Each of the HPy C^(-)ligands is coordinated with one Cu^(2+)to form the(4,8)-connected scu-net structure of compound 2[(Cu Cl_(2))_(2)Th_(6)(HPy C)_8(HCOO)_(4)].In compound 3[(Cu Cl_(2))_(2)Th_(6)(HPy C)_(10)(HCOO)_(4)],ten of the formate ligands of preassembled Th_(6)cluster are replaced by HPy C^(-)ligands.Compared with compound 2,the two extra HPy C^(-)ligands in the equatorial plane of the Th_(6)cluster in compound 3 are not further connected to copper ions.Therefore,the topology structure of compound 3 is same with that of compound 2.Compound 4[(Cu_(3)Cl_(2))(Cu Cl_(2))Th_(6)(Py C)_(3)(HPy C)_(4)(HCOO)_(5)]contains three kinds of metal nodes,Th_(6)cluster,Cu_(3)cluster and mononuclear Cu^(2+),and exhibits a novel(5,7)-connected net structure,which was first discovered in actinide MOFs.Furthermore,considering the satisfactory stability of compound 4 and its unsaturated metal nodes and Lewis acid sites,the catalysis of cycloaddition of CO_(2)was further studied.We found that this thorium-copper heterometallic cluster organic framework can be used as a potential actinide functional material for catalyzing the efficient CO_(2)conversion to value-added products.