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Local experts are critical for many location-sensitive information needs, and yet there is a research gap in our understanding of the factors impacting who is recognized as a local expert and in methods for discovering local experts. Hence, in this article, we explore a geo-spatial learning-to-rank framework for identifying local experts. Three of the key features of the proposed approach are: (i) a learning-based framework for integrating multiple user-based, content-based, list-based, and crowd-based factors impacting local expertise that leverages the fine-grained GPS coordinates of millions of social media users; (ii) a location-sensitive random walk that propagates crowd knowledge of a candidate’s expertise; and (iii) a comprehensive controlled study over AMT-labeled local experts on eight topics and in four cities. We find significant improvements of local expert finding versus two state-of-the-art alternatives, as well as evidence for the generalizability of local expert ranking models to new topics and new locations.

Binuclear nitro-phthalocyanines (M2(PcTN)2O) were synthesized and reduced to binuclear amino-phthalocyanines (M2(PcTA)2O) as high-efficiency catalysts to promote the electrochemical properties of lithium/thionyl chloride (Li/SOCl2) battery. The catalytic performances of M2(PcTN)2O and M2(PcTA)2O were evaluated by adding a small amount of catalysts into the electrolyte. Elemental analysis, Fourier transform infrared (FTIR), ultraviolet-visible (UV-vis), Thermal technique (TGA) and scanning electron microscope (SEM) were employed to characterize the final products. The discharge time of the battery catalyzed by M2(PcTN)2O and M2(PcTA)2O was lengthened by 181∼510 s and 198∼564 s, respectively. The results reveal that battery capacities had been improved approximately 16.74∼47.91% and energy increased by 14.95∼44.80% compared with the bare batteries, which should be attributed to the electronic configurations of the metal ions, the phthalocyanine rings and the synergistic effect. In addition, according to the cyclic voltammetric analysis, catalytic mechanism of the synthesized binuclear phthalocyanines in the battery was speculated.

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