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Articles by Li Chen
Total Records ( 8 ) for Li Chen
  Zhixue Wang , Hongyue He , Li Chen and Ying Zhang
  UML activity model is mainly used to model the behaviors of software system and the quality of activity model will influence the quality of software system. But because the UML activity model lacks strictly formal semantics, it is difficult to make formal semantics analysis and checking for activity model. An ontology based method of semantics checking for activity model is proposed. The semantics of activity model is divided into static semantics and dynamic semantics. The static semantics is transformed into OWL DL by an algorithm, and the dynamic semantics is described by DL-Safe rules. Then the consistency of UML activity model is analyzed and some model checking rules are defined, which enables model consistency checking by using an ontology reasoning tool.
  Yi Zhu , Xingming Sun , Zhihua Xia , Li Chen , Tao Li and Daxing Zhang
  With the growing popularity of cloud computing, more and more users are willing to outsource their private data to the cloud. To ensure the security of data, data owners usually encrypted their private data before outsourcing them to the cloud server. Though data encryption improves the security of data, it increases the difficulty of data operating. This study focuses on the search of encrypted images in the cloud and proposes an efficient similarity retrieval scheme over encrypted images. The proposed scheme enables data owners to outsource their personal images and the content-based image retrieval service to the cloud without revealing the actual content of the image database to the cloud. The proposed scheme in this study supports the global feature based image retrieval methods under the Euclidean distance metric. Besides, rigorous security analysis and extensive experiments show that the proposed scheme is secure and efficient.
  Yihui Liu , Jideng Ma , Li Chen , Pengbo Lou , Jun Zhou , Mingzhou Li and Xuewei Li
  High-throughput sequencing of two small RNA libraries derived from immature (20 days old) and mature (210 day old) porcine testis samples yielded over 20 million high-quality reads. Researchers detected 461 mature microRNAs (miRNAs) encoded by 277 precursor (pre)-miRNAs of which 428 were unique. In total, 303 unique miRNAs of (428, 70.79%) were differentially expressed between immature and mature porcine testes. Compared with immature testis, 95 unique miRNAs were up-regulated and 208 unique miRNAs were down-regulated in mature testis. Strikingly, researchers found that most miRNAs and differentially expressed miRNAs were preferentially located on the X chromosome which implied their crucial roles in the sex-determination system. Furthermore, GO and KEGG analyses of the target genes that were predicted from the highly abundant differentially expressed miRNAs between mature and immature porcine testes illustrate the likely roles for these miRNAs in spermatogenesis. The study indicates that miRNAs are extensively involved in spermatogenesis and that unraveling miRNA functions in the testis will further the understanding of regulatory mechanisms of mammalian spermatogenesis and male infertility treatment.
  Li Chen and Kuo-Wei Lin
  With the gradual decreasing birth rate in Taiwan, many nursery schools are finding it difficult to recruit enough children and some are even forced to close. This study explores the operation dilemmas that nursery schools face and how to adjust and improve their operation structure under a low birth rate environment. Our findings show that nursery schools should not only adjust their organizational structure, but also work out an operation strategy for meeting the needs of their customers (i.e., parents) in order to survive, grow and thrive.
  Heng- Da Gu , Li Chen and Jing-Xi Yan
  Chiral side-chain liquid-crystalline (LC) polysiloxanes containing isosorbide groups were graft copolymerised with poly(methylhydrogeno)siloxane, a chiral LC monomer 6-(4-methoxy-benzoyloxy)-hexahydro-furo[3,2-b]furan-3-yl 4'-(4-undec-10-enoyloxy-benzoyloxy)-biphenyl-4-yl adipate and a nematic LC monomer 4'-(4-methoxy-benzoyloxy)-biphenyl-4-yl 4-(2-undec-10-enoyloxy-ethoxy)-benzoate. The chemical structures and LC properties of the monomers and polymers were characterised by use of various experimental techniques including Fourier transform infrared spectroscopy (FTIR), 1H-nuclear magnetic resonance (NMR), element analyses (EA), differential scanning calorimetry (DSC), polarised optical microscopy (POM) and X-ray diffraction (XRD). All the chiral LC polymers showed LC properties with very wide mesophase temperature ranges and the chiral component in the LC polymer systems lead to the appearance of a cholesteric phase. The polymers bearing most chiral LC monomer component showed smectic phases by reason of regular structures in the polymer systems. With the increase of another nematic LC monomer in the polymers, the regular polymer structures were destroyed because of different chemical structures between the two kinds of LC monomers, leading to the disappearance of the smectic arrangement.
  Li Chen and Kiran Madura
  Rad23 is required for efficient protein degradation and performs an important role in nucleotide excision repair. Saccharomyces cerevisiae Rad23, and its human counterpart (hHR23), are present in a complex containing the DNA repair factor Rad4 (termed XPC, for xeroderma pigmentosum group C, in humans). XPC/hHR23 was also reported to bind centrin-2, a member of the superfamily of calcium-binding EF-hand proteins. We report here that yeast centrin, which is encoded by CDC31, is similarly present in a complex with Rad4/Rad23 (called NEF2). The interaction between Cdc31 and Rad23/Rad4 varied by growth phase and reflected oscillations in Cdc31 levels. Strikingly, a cdc31 mutant that formed a weaker interaction with Rad4 showed sensitivity to UV light. Based on the dual function of Rad23, in both DNA repair and protein degradation, we questioned if Cdc31 also participated in protein degradation. We report here that Cdc31 binds the proteasome and multiubiquitinated proteins through its carboxy-terminal EF-hand motifs. Moreover, cdc31 mutants were highly sensitive to drugs that cause protein damage, failed to efficiently degrade proteolytic substrates, and formed altered interactions with the proteasome. These findings reveal for the first time a new role for centrin/Cdc31 in protein degradation.
  Hui Zhang , Li Chen , SiFeng Zhao , Juan Ren and XiaoLei Cao
  Bacillus subtilis S44 is a promising plant growth-promoting rhizobacterium and a potent biocontrol agent isolated from cotton rhizosphere. The ituD gene was cloned and identified from S44. A suicide vector containing ituD gene from B. subtilis S44 was recombined into the B. subtilis S44 chromosome to disrupt the ituD gene. Recombination was demonstrated by PCR, antifungal activity and HPLC confirmed the loss of the ituD gene. The growth rate of the recombinant is severely depressed compared with wild type and tetracycline had no effect on the growth rate the mutant strains. Antifungal activity in cell-free extracts of the recombinant has almost no antifungal activity compared with the wild strain. HPLC analysis show that the wild strian produce iturin A at an amount of 89.4 μg mL-1 while the ituD mutant only 3.41 μg mL-1. In pot and plot tests, the control effects of S44 treatment were 80.30 and 72.97%, respectively. The mutant strains S1 and S2 exhibit no control effect of cotton Rhizoctoniosis. These results suggest that the ituD gene was important for iturin A synthesis and biocontrol activity of S44.
  Robert J. Belton , Li Chen , Fernando S. Mesquita and Romana A. Nowak
  The metastatic spread of a tumor is dependent upon the ability of the tumor to stimulate surrounding stromal cells to express enzymes required for tissue remodeling. The immunoglobulin superfamily protein basigin (EMMPRIN/CD147) is a cell surface glycoprotein expressed by tumor cells that stimulates matrix metalloproteinase and vascular endothelial growth factor expression in stromal cells. The ability of basigin to stimulate expression of molecules involved in tissue remodeling and angiogenesis makes basigin a potential target for the development of strategies to block metastasis. However, the identity of the cell surface receptor for basigin remains controversial. The goal of this study was to determine the identity of the receptor for basigin. Using a novel recombinant basigin protein (rBSG) corresponding to the extracellular domain of basigin, it was demonstrated that the native, nonglycosylated rBSG protein forms dimers in solution. Furthermore, rBSG binds to the surface of uterine fibroblasts, activates the ERK1/2 signaling pathway, and induces expression of matrix metalloproteinases 1, 2, and 3. Proteins that interact with rBSG were isolated using a biotin label transfer technique and sequenced by matrix-assisted laser desorption ionization tandem mass spectrophotometry. The results demonstrate that rBSG interacts with basigin expressed on the surface of fibroblasts and is subsequently internalized. During internalization, rBSG associates with a novel form of human basigin (basigin-3). It was concluded that cell surface basigin functions as a membrane receptor for soluble basigin and this homophilic interaction is not dependent upon glycosylation of the basigin ligand.
 
 
 
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