Collaborative Learning Group Formation with Density Clustering

Mengxiong Zhou,Yanming Ye,Yizhi Ren,Yueshen Xu 보안공학연구지원센터 2016 International Journal of Grid and Distributed Comp Vol.9 No.6

The formation of the collaborative learning group is a challenging problem, especially the principle construction and multi-objective optimization. In this paper, we propose an improved density clustering algorithm, and further implement the group formation based on the proposed algorithm. The proposed algorithm first constructs the distance matrix for learners, and clusters learners into different groups. After the random selection of the initial cluster centers, our algorithm achieves superior clustering result by iteratively adjusting the clustering centers. We conduct sufficient experiments and the experimental results demonstrate that the proposed algorithm well satisfies our aim, that is, inter-group heterogeneity maximization and intra-group homogeneity maximization.

Characterization of the global transcriptome using Illumina sequencing and novel microsatellite marker information in seashore paspalum

Xinping Jia,Yanming Deng,Xiaobo Sun,Lijian Liang,Xiaoqing Ye 한국유전학회 2015 Genes & Genomics Vol.37 No.1

Seashore paspalum (Paspalum vaginatum O. Swartz) is a halophytic warm-season perennial grass,which plays an important role in protection of environment. However, very limited transcriptomic and genomic informationare currently available for seashore paspalum. Inthis study, the seashore paspalum transcriptome weresequenced using Illumina paired-end sequencing technology. In total, 32,603 unigenes with an average length of970 bp were obtained by de novo assembly. Of the unigenes,25,411 unigenes (77.94 %) had significant similaritywith known proteins in the NCBI non-redundant proteinand Swiss-Prot databases. Of these annotated unigenes,20,962 and 10,620 unigenes were assigned to gene ontologycategories and clusters of orthologous groups,respectively. A total of 4,699 unigenes were mapped into118 Kyoto Encyclopedia of Genes and Genomes pathways. In addition, 3,010 potential simple sequence repeats (SSRs)were predicted for microsatellite analyse. Tri-nucleotidewas the dominant repeat (1,583, 52.58 %), followed by dinucleotide(975, 32.39 %) and tetra-nucleotide (217,7.21 %). Fifty SSR sites were randomly selected for validationand development of EST–SSR markers. This studyprovided the global sequence data for seashore paspalumand demonstrated that the Illumina paired-end sequencingis a fast and cost-effective approach to gene discovery andmolecular marker development.

PVA Hydrogel Functionalization via PET-RAFT Grafting with Glycidyl Methacrylate and Immobilization with 2-Hydroxypropyltrimethyl Ammonium Chloride Chitosan via Ring-Open Reaction

Jinsheng Zhou,Yanming Lin,Lin Ye,Ling Wang,Li Zhou,Huiyuan Hu,Qilong Zhang,Hui Yang,Zhongkuan Luo 한국고분자학회 2019 Macromolecular Research Vol.27 No.11

To solve the biofouling problem of polyvinyl alcohol (PVA) hydrogel as the artificial cornea, glycidyl methacrylate (GMA) and 2-hydroxypropyltrimethyl ammonium chloride chitosan (HACC) were grafted on the surface of PVA hydrogel via a new method of photoinduced electron transfer–reversible addition fragmentation chain transfer (PET-RAFT) polymerization and ring-open reaction. Both attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscope (SEM), and thermogravimetric analysis (TGA) confirmed that GMA and HACC were successfully grafted on the surface of PVA hydrogel. A series of experiments to test the hydrophilicity of PVA hydrogel showed that it became hydrophobic due to the introduction of hydrophobic groups after grafting with GMA and HACC. In addition, cytotoxicity in vitro of PVA-g-p(GMA-HACC) hydrogel could be considered as not cytotoxicity according to ISO 10993-5: 2009. The anti-fouling property of hydrogel decreased after grafting with GMA due to the hydrophobic surface, while increased after grafting with HACC due to the steric repulsion of p(GMA-HACC) polymer brush. It’s no doubt that PET-RAFT was a feasible and reliable surface modification method which could be used in many biomolecules due to the excellent advantages.

Extension of indacenodithiophene backbone conjugation enables efficient asymmetric A-D-A type non-fullerene acceptors

Song, Jiali,Li, Chao,Ye, Linglong,Koh, Changwoo,Cai, Yunhao,Wei, Donghui,Woo, Han Young,Sun, Yanming The Royal Society of Chemistry 2018 Journal of Materials Chemistry A Vol.6 No.39

<P>A novel strategy involving judiciously fusing one thiophene/thieno[3,2-<I>b</I>]thiophene on only one side of an indacenodithiophene (IDT) unit to extend IDT backbone conjugation was developed, and three A-D-A type non-fullerene small molecules (TPT-2F, TPTT-2F, and TPTTT-2F) were designed and synthesized to investigate the influence of the extent of IDT core conjugation on their photovoltaic properties. Extending the IDT core conjugation could broaden absorption, upshift the lowest unoccupied molecular orbital (LUMO) energy level, enhance electron mobility, and increase intermolecular π-π stacking. When these three non-fullerene acceptors were applied in organic solar cells (OSCs), simultaneous enhancement of the open-circuit voltage (<I>V</I>oc), short-circuit current (<I>J</I>sc), and fill factor (FF) was obtained, with the degree of enhancement following the order TPT-2F < TPTT-2F < TPTTT-2F. As a result, the TPTTT-2F based OSCs yielded a high PCE of 12.03%. To the best of our knowledge, the PCE of 12.03% is among the highest values for asymmetric non-fullerene acceptor based OSCs so far. These results demonstrate that extending the conjugation of the IDT core is an effective approach to design highly efficient asymmetric non-fullerene acceptors.</P>

Effect of Ion Source Current on the Microstructure and Properties of Cr-DLC Coatings Prepared by Ion Beam-Assisted Arc Ion Plating

Yao Cai,Huidong Liu,Ye Ma,Qiang Wan,Hao Cheng,Yan Liu,Yanming Chen,Qingsong Mei,Bing Yang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.5

Cr-containing diamond-like carbon (Cr-DLC) nanocomposite coatings were synthesized by ion beam-assisted arc ion plating with varying hollow cathode ion source (HCIS) currents. The morphologies, compositions and microstructures were characterized by scanning electronic microscopy (SEM), atomic force microscopy (AFM), X-Ray photoelectron spectrometer (XPS), Raman spectroscopy, grazing incidence X-ray diffraction (GIXRD) and high-resolution transmission electron microscopy (HRTEM). Hardness and friction coefficient were investigated by using nanoindentation and ball-on-disc tribometer, respectively. With no HCIS current, the coating exhibits the maximal growth rate and a rough surface, as well as lower hardness and elastic modulus. With the increasing HCIS current from 40 A to 80 A, the growth rate and the content of chromium carbide decrease obviously, the sp3/sp2 ratio increases initially to the maximum at the HCIS current of 60 A, the highest hardness and elastic modulus are obtained at the HCIS current of 50 A. It is also revealed that moderate HCIS current can reduce surface roughness obviously and promote tribological properties. The correlation of the HCIS current with the microstructure and performance of Cr-DLC coating has been established.

Asymmetric selenophene-based non-fullerene acceptors for high-performance organic solar cells

Li, Chao,Xia, Tian,Song, Jiali,Fu, Huiting,Ryu, Hwa Sook,Weng, Kangkang,Ye, Linglong,Woo, Han Young,Sun, Yanming The Royal Society of Chemistry 2019 Journal of materials chemistry. A, Materials for e Vol.7 No.4

<P>Compared to thiophene-based non-fullerene acceptors (NFAs), selenophene-based NFAs have received much less attention. And organic solar cells (OSCs) based on selenophene-containing NFAs typically exhibit relatively low power conversion efficiency (PCE < 12%) and fill factor (FF < 70%). In this contribution, we have designed and synthesized two asymmetric selenophene-based NFAs, named SePTT-2F and SePTTT-2F, which possess the same end-capping group but different selenophene-containing conjugated backbones. On comparing the two NFAs, SePTTT-2F with more extended conjugation in the backbone was found to have almost the same maximum absorption peak and optical bandgap in film as SePTT-2F but an up-shifted lowest unoccupied molecular orbital (LUMO) energy level and higher electron mobility. By pairing the NFAs with the polymer donor PBT1-C, the resultant blend film based on SePTTT-2F exhibited higher and more balanced charge mobilities and more efficient exciton dissociation and charge collection in comparison with the SePTT-2F-based blend film. As a result, OSCs based on SePTTT-2F delivered an impressively high PCE of 12.24% with an outstanding FF of 75.9%, much higher than those of the SePTT-2F-based OSCs. To the best of our knowledge, the PCE of 12.24% and FF of 75.9% are among the highest values reported in the literature so far for both the parameters amongst selenophene-containing NFA-based OSCs. Our results demonstrate that extending the conjugation in the selenophene-containing backbone is an effective strategy to design highly efficient selenophene-based NFAs.</P>