Nankai University

About: Nankai University is a education organization based out in Tianjin, China. It is known for research contribution in the topics: Catalysis & Adsorption. The organization has 42964 authors who have published 51866 publications receiving 1127896 citations. The organization is also known as: Nánkāi Dàxué.

An evaluation on feature selection for text clustering

Abstract: Feature selection methods have been successfully applied to text categorization but seldom applied to text clustering due to the unavailability of class label information. In this paper, we first give empirical evidence that feature selection methods can improve the efficiency and performance of text clustering algorithm. Then we propose a new feature selection method called "Term Contribution (TC)" and perform a comparative study on a variety of feature selection methods for text clustering, including Document Frequency (DF), Term Strength (TS), Entropy-based (En), Information Gain (IG) and χ2 statistic (CHI). Finally, we propose an "Iterative Feature Selection (IF)" method that addresses the unavailability of label problem by utilizing effective supervised feature selection method to iteratively select features and perform clustering. Detailed experimental results on Web Directory data are provided in the paper.

Engineering electrocatalytic activity in nanosized perovskite cobaltite through surface spin-state transition.

Abstract: The activity of electrocatalysts exhibits a strongly dependence on their electronic structures. Specifically, for perovskite oxides, Shao-Horn and co-workers have reported a correlation between the oxygen evolution reaction activity and the eg orbital occupation of transition-metal ions, which provides guidelines for the design of highly active catalysts. Here we demonstrate a facile method to engineer the eg filling of perovskite cobaltite LaCoO3 for improving the oxygen evolution reaction activity. By reducing the particle size to ∼80 nm, the eg filling of cobalt ions is successfully increased from unity to near the optimal configuration of 1.2 expected by Shao-Horn’s principle. Consequently, the activity is significantly enhanced, comparable to those of recently reported cobalt oxides with eg∼1.2 configurations. This enhancement is ascribed to the emergence of spin-state transition from low-spin to high-spin states for cobalt ions at the surface of the nanoparticles, leading to more active sites with increased reactivity. The activity of electrocatalysts exhibits a strong dependence on their electronic structures. Here, the authors manipulate the eg filling of perovskite cobaltite LaCoO3nanoparticles by changing particle size and show improved oxygen evolution activity with increased numbers of surface high-spin cobalt ions.

A Bimetallic Lanthanide Metal-Organic Material as a Self-Calibrating Color-Gradient Luminescent Sensor.

Abstract: A new bimetallic lanthanide metal-organic framework [Eu0.5 Tb1.5 (FDA)3 ] (H2 FDA = 2,5-furandicarboxylic acid) exhibits high-sensitivity luminescent sensing of mixtures of organic compounds and can work over a large range of volume ratios. The self-calibrating behavior of this color-gradient luminescent sensor is presented for the first time.

Co3S4 hollow nanospheres grown on graphene as advanced electrode materials for supercapacitors

Abstract: A novel nanocomposite of Co3S4 hollow nanospheres grown on reduced graphene oxide (rGO) has been synthesized by a facile two-step method and used as an advanced electrode material for supercapacitors. The intriguing formation and attachment mechanism of these Co3S4 hollow nanospheres on graphene are investigated. More importantly, it is found that the electrochemical performance of the as-prepared nanocomposite could be effectively improved by the chemical interaction between rGO and Co3S4. Specifically, it exhibits a high specific discharge capacitance of 675.9 F g−1 at 0.5 A g−1 and 521.7 F g−1 at 5 A g−1. These results suggest the great promise of fabricating graphene-supported hybrid materials for high-performance energy applications.