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Now showing items 113 - 128 of 403

  • Synthesis and Characterization of TiAl-Based Nanocomposites by a Melt Electromagnetic Stirring Process

    Zhang, Zhiyong   Wang, Yanli   Xu, Xiangjun   Liang, Yongfeng   Zhang, Laiqi   Lin, Junpin  

    Ceramic nanoparticles were considered difficult to be dispersed well in liquid metal, especially in non-reactive systems, by stir mixing methods due to their high specific surface energy. In this paper, an electromagnetic stirring process was exploited to disperse ceramic nanoparticles in an active TiAl alloy melt. The results indicate that finely dispersed nanoparticles can be obtained by stir mixing with the aid of reactive wetting. The presence of nanoparticles during solidification can refine the primary dendrites dramatically, which was primarily determined by the extent of particle pushing at the liquid-solid interface. Among the studied particles, TiC can refine the (gamma + alpha(2)) lamellar colonies, which is attributed to the dissolution of carbon and subsequent precipitation of Ti2AlC during L + beta -> beta + alpha. The Vickers hardness of the nanocomposites as a function of stirring time was tested, and the Ti-45Al/TiC nanocomposite produced by 10 min stir mixing has the highest value, measuring 450 HV.
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  • Hierarchical SnO2-Fe2O3 heterostructures as lithium-ion battery anodes

    Wang, Yanli   Xu, Jingjie   Wu, Hao   Xu, Ming   Peng, Zheng   Zheng, Gengfeng  

    We report a facile, two-step hydrothermal growth method to synthesize a novel hierarchical SnO2-Fe2O3 heterostructure, consisting of a micron-sized primary SnO2 nanosheet base and sub-10 nm diameter Fe2O3 nanorod branches grown on the nanosheet surface. In addition to the high theoretical lithium storage capacities of both oxide components, the two-dimensional SnO2 nanosheets offer a high surface area and fast charge transport pathways, and the one-dimensional alpha-Fe2O3 nanorods serve as structural spacers between individual SnO2 nanosheets, thus leading to an excellent anode material for lithium-ion batteries with enhanced capacity and cycling property. As a proof-of-concept, lithium-ion battery anodes made of these hierarchical SnO2-Fe2O3 heterostructures have shown a high initial discharge capacity of 1632 mA h g(-1) at 400 mA g(-1), which is retained at 325 mA h g(-1) after 50 cycles, better than the anodes made of pure SnO2 nanosheets and alpha-Fe2O3 nanorods grown under similar conditions.
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  • Flat detector cone-beam CT-guided percutaneous needle biopsy of mediastinal lesions:preliminary experience

    Jiao, Dechao   Huang, Kai   Wu, Gang   Wang, Yanli   Han, Xinwei  

    The purpose of this study was to evaluate the usefulness of flat detector cone-beam CT-guided CBCT percutaneous needle biopsy (PNB) of mediastinal lesions. A total of 100 patients with 100 solid mediastinal lesions were retrospectively enrolled to undergo percutaneous needle biopsy (PNB) procedures. The mean diameter of lesions was 4.4 +/- A 1.8 cm (range 1.8-9.0 cm). The needle path was carefully planned and calculated on the CBCT virtual navigation guidance system, which acquired 3D CT-like cross-sectional images. Diagnostic performance, procedure details, complication rate, and patient radiation exposure were investigated. The technical success rate of PNB under CBCT virtual navigation system was 100 % (100/100). The sensitivity, specificity, and accuracy of PNB of small nodules under iGuide CBCT virtual navigation guidance were 95.1 % (79/83), 100 % (12/12), and 95.7 % (91/95), respectively. The number of biopsies and CBCT acquisitions were 2.6 +/- A 1.2 (range 1-6) and 3.0 +/- A 1.1 (range 2-8), respectively. Complications occurred in five (5.0 %) cases. The mean total procedure time was 11.70 +/- A 3.44 min (range 6-27 min), resulting in a mean exposure dose of 9.7 +/- A 4.3 mSv. Flat detector cone-beam CT-guided PNB is an accurate and safe diagnostic method for mediastinal lesions.
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  • SUMOylation at K707 of DGCR8 controls direct function of primary microRNA.

    Zhu, Changhong   Chen, Cheng   Huang, Jian   Zhang, Hailong   Zhao, Xian   Deng, Rong   Dou, Jinzhuo   Jin, Hui   Chen, Ran   Xu, Ming   Chen, Qin   Wang, Yanli   Yu, Jianxiu  

    DGCR8 (DiGeorge syndrome critical region gene 8) is essential for primary microRNA (pri-miRNA) processing in the cell nucleus. It specifically combines with Drosha, a nuclear RNase III enzyme, to form the Microprocessor complex (MC) that cleaves pri-miRNA to precursor miRNA (pre-miRNA), which is further processed to mature miRNA by Dicer, a cytoplasmic RNase III enzyme. Increasing evidences suggest that pri-/pre-miRNAs have direct functions in regulation of gene expression, however the underlying mechanism how it is fine-tuned remains unclear. Here we find that DGCR8 is modified by SUMO1 at the major site K(707), which can be promoted by its ERK-activated phosphorylation. SUMOylation of DGCR8 enhances the protein stability by preventing the degradation via the ubiquitin proteasome pathway. More importantly, SUMOylation of DGCR8 does not alter its association with Drosha, the MC activity and miRNA biogenesis, but rather influences its affinity with pri-miRNAs. This altered affinity of DGCR8 with pri-miRNAs seems to control the direct functions of pri-miRNAs in recognition and repression of the target mRNAs, which is evidently linked to the DGCR8 function in regulation of tumorigenesis and cell migration. Collectively, our data suggest a novel mechanism that SUMOylation of DGCR8 controls direct functions of pri-miRNAs in gene silencing. =C2=A9 The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.
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  • Computational design of anti-CRISPR proteins with improved inhibition potency

    Mathony, Jan   Harteveld, Zander   Schmelas, Carolin   Upmeier zu Belzen, Julius   Aschenbrenner, Sabine   Sun, Wei   Hoffmann, Mareike D.   Stengl, Christina   Scheck, Andreas   Georgeon, Sandrine   Rosset, Stéphane   Wang, Yanli   Grimm, Dirk   Eils, Roland   Correia, Bruno E.   Niopek, Dominik  

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  • Murine Placental‐Fetal Phosphate Dyshomeostasis Caused by an Xpr1 Deficiency Accelerates Placental Calcification and Restricts Fetal Growth in Late Gestation

    Xu, Xuan   Li, Xiunan   Sun, Hao   Cao, Zhijian   Gao, Ruixi   Niu, Tingting   Wang, Yanli   Ma, Tingbin   Chen, Rui   Wang, Cheng   Yang, Zhengang   Liu, Jing Yu  

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  • Renovascular Hypertension Aggravates Atherosclerosis in Cholesterol-Fed Rabbits

    Chen, Yajie   Waqar, Ahmed Bilal   Yan, Haizhao   Wang, Yanli   Liang, Jingyan   Fan, Jianglin  

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  • Location protection method for mobile crowd sensing based on local differential privacy preference

    Wang, Jian   Wang, Yanli   Zhao, Guosheng   Zhao, Zhongnan  

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  • Direct Imaging of Titania Nanotubes Located in Mouse Neural Stem Cell Nuclei

    Wang, Yanli   Wang, Jia   Deng, Xiaoyong   Wang, Jiao   Wang, Haifang   Wu, Minghong   Jiao, Zheng   Liu, Yuanfang  

    Titania nanotubes (TiO(2)-NTs) are a potential drug vehicle for use in nanomedicine. To this end, a preliminary study of the interaction of a model cell with TiO(2)-NTs has been carried out. TiO(2)-NTs were first conjugated with a fluorescent label, fluorescein isothiocyanate (FITC). FITC-conjugated titania nanotubes (FITC-TiO(2)-NTs) internalized in mouse neural stem cells (NSCs, line C17.2) can be directly imaged by confocal microscopy. The confocal imaging showed that FITC-TiO(2)-NTs readily entered into the cells. After co-incubation with cells for 24 h, FITC-TiO(2)-NTs localized around the cell nucleus without crossing the karyotheca. More interestingly, the nanotubes passed through the karyotheca entering the cell nucleus after co-incubation for 48 h. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) were also employed in tracking the nanotubes in the cell. These results will be of benefit in future studies of TiO(2)-NTs for use as a drug vehicle, particularly for DNA-targeting drugs.
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  • Vapor phase ortho-selective alkylation of phenol with methanol over silica-manganese mixed oxide catalysts

    Wang, Yanli   Song, Yingying   Huo, Weitao   Jia, Mingjun   Jing, Xiaoyan   Yang, Piaoping   Yang, Zhi   Liu, Gang   Zhang, Wenxiang  

    The gas phase catalytic alkylation of phenol with methanol was investigated over a series of silica-manganese mixed oxide catalysts. The molar ratio of Si/Mn, the calcination temperature and the reaction temperature have considerable effect on the catalytic performance of the catalysts. All the Si-Mn mixed oxides are the active catalysts for the selective production of o-cresol and 2,6-xylenol. Among them, the catalyst with Si/Mn = 0.02, which is calcined at 773 K, shows the highest catalytic activity and selectivity to 2,6-xylenol. The existence of suitable Lewis acidic sites and/or basic sites might be responsible for the high activity and the ortho-selectivity of Si-Mn mixed oxides. During the reaction course, the partial reduction of Mn2O3/Mn3O4 can result in the decrease of Lewis acidity strength, which might be the main reason for the decrease of the selectivity to 2.6-xylenol. (C) 2012 Elsevier B.V. All rights reserved.
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  • Crystal structure of homoserine O-acetyltransferase from Leptospira interrogans RID G-3306-2010 RID B-5001-2010

    Wang, Mingzhu   Liu, Lin   Wang, Yanli   Wei, Zhi-Yi   Zhang, Ping   Li, Ylkun   Jiang, Xiaohua   Xu, Hang   Gong, Welmin  

    Homoserine O-acetyltransferase (HTA, EC 2.3.1.31) initiates methionine biosynthesis pathway by catalyzing the transfer of acetyl group from acetyl-CoA to homoserine. This study reports the crystal structure of HTA from Leptospira interrogans determined at 2.2A resolution using selenomethionyl single-wavelength anomalous diffraction method. HTA is modular and consists of two structurally distinct domains-a core alpha/beta domain containing the catalytic site and a helical bundle called the lid domain. Overall, the structure fold belongs to alpha/beta hydrolase superfamily with the characteristic 'catalytic triad' residues in the active site. Detailed structure analysis showed that the catalytic histidine and serine are both present in two conformations, which may be involved in the catalytic mechanism for acetyl transfer. (C) 2007 Elsevier Inc. All rights reserved.
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  • The TNF-alpha-induced expression of miR-130b protects cervical cancer cells from the cytotoxicity of TNF-alpha

    Yang, Lei   Wang, Yanli   Shi, Shuainan   Xie, Lili   Liu, Tao   Wang, Yuliang   Mu, Hong  

    Tumour necrosis factor alpha (TNF-alpha) is a multifunctional cytokine and has the capacity both to promote cell growth and to kill tumour cells by inducing cell apoptosis. However, many tumour cells develop resistance to the toxic effects of TNF-alpha. Thus, understanding the mechanism underlying the resistance of tumours to TNF-alpha toxicity and finding ways to overcome this resistance are urgently needed. In this study, we discovered that two cervical cancer cell lines, Hela and Siha, showed null responses to TNF-alpha cytotoxicity. However, in these cell lines, TNF-alpha stimulation promoted the expression of miR-130b and downregulated the expression of PTEN gene, which encodes a dual-specificity phosphatase that acts as a tumour suppressor. Blockade of miR-130b function or overexpression of PTEN gene sensitized cells to TNF-alpha cytotoxicity. Regression analyses revealed that there were reverse relationships between the cellular levels of miR-130b and PTEN mRNA in cervical cancer cells. Gain- and loss-of-function assays demonstrated that there were causal relationships between the increase in miR-130b levels and the reduction in PTEN mRNA or PTEN protein levels. In silico analysis revealed that there were two miR-130b target sites within the 3'UTR of PTEN mRNA and experimental evidences demonstrated that miR-130b repressed the expression of PTEN gene by binding directly to the 3'UTR of PTEN mRNA. These data suggest miR-130b expression as a target to be inhibited to make tumour cells more sensitive to the toxic impact of TNF-alpha.
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  • Understanding the core of RNA interference:The dynamic aspects of Argonaute-mediated processes

    Zhu, Lizhe   Jiang, Hanlun   Sheong, Fu Kit   Cui, Xuefeng   Wang, Yanli   Gao, Xin   Huang, Xuhui  

    At the core of RNA interference, the Argonaute proteins (Ago) load and utilize small guide nucleic acids to silence mRNAs or cleave foreign nucleic acids in a sequence specific manner. In recent years, based on extensive structural studies of Ago and its interaction with the nucleic acids, considerable progress has been made to reveal the dynamic aspects of various Ago-mediated processes. Here we review these novel insights into the guide-strand loading, duplex unwinding, and effects of seed mismatch, with a focus on two representative Agos, the human Ago 2 (hAgo2) and the bacterial Thermus thermophilus Ago (TtAgo). In particular, comprehensive molecular simulation studies revealed that although sharing similar overall structures, the two Agos have vastly different conformational landscapes and guide-strand loading mechanisms because of the distinct rigidity of their Ll-PAZ hinge. Given the central role of the PAZ motions in regulating the exposure of the nucleic acid binding channel, these findings exemplify the importance of protein motions in distinguishing the overlapping, yet distinct, mechanisms of Ago mediated processes in different organisms. (C) 2016 Elsevier Ltd. All rights reserved.
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  • MiR-130b suppresses prostate cancer metastasis through down-regulation of MMP2.

    Chen, Qin   Zhao, Xian   Zhang, Hailong   Yuan, Haihua   Zhu, Miaojun   Sun, Qian   Lai, Xueping   Wang, Yanli   Huang, Jian   Yan, Jianshe   Yu, Jianxiu  

    Prostate cancer (PCa) is the most prevalent malignant carcinoma among males in western countries. Currently no treatments can cure advanced prostate cancers, so new diagnostic and therapeutic strategies are in urgent need. At present limited knowledge is available concerning the roles of dysregulated microRNAs in prostate cancer metastasis. In this study, we found that the expression of miR-130b was significantly down-regulated in prostate cancer cell lines and clinical prostate cancer tissues. Enforced over-expression of miR-130b in prostate cancer cells suppressed whereas knock-down of miR-130b increased cell migration and invasion. Using mouse model, we revealed that miR-130b-expressed prostate cancer cells displayed significant reduction in tumor metastasis. Furthermore, we identified and validated matrix metalloproteinase-2 (MMP2) as a direct target of miR-130b. Ectopic expression of MMP2 rescued miR-130b-suppressed cell migration and invasion, and knock-down of MMP2 antagonized the effect of silencing miR-130b.Taken together, our data reveal for the first time that miR-130b exerts a suppressive effect in prostate cancer metastasis through down-regulation of MMP2. =C2=A9 2014 Wiley Periodicals, Inc.
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  • A Modeling Study for Structure Features of beta-N-acetyl-D-hexosaminidase from Ostrinia furnacalis and its Novel Inhibitor Allosamidin: Species Selectivity and Multi-Target Characteristics

    Wang, Yanli   Liu, Tian   Yang, Qing   Li, Zhong   Qian, Xuhong  

    Insect beta-N-acetyl-D-hexosaminidase, a chitin degrading enzyme, is physiologically important during the unique life cycle of the insect. OfHex1, a beta-N-acetyl-D-hexosaminidase from the insect, Ostrinia furna, which was obtained by our laboratory (Gen Bank No.: ABI81756.1), was studied by molecular modeling as well as by molecular docking with its inhibitor, allosamidin. 3D model of OfHex1 was built through the ligand-supported homology modeling approach. The binding modes of its substrate and inhibitor were proposed through docking and cluster analysis. The pockets size and shape of OfHex1 differ from that of human beta-N-acetyl-D-hexosaminidase, which determined that allosamidin can selectively inhibit OfHex1 instead of human beta-N-acetyl-D-hexosaminidase. Moreover, the multi-target characteristics of allosamidin that inhibit enzymes from different families, OfHex1 (EC 3.2.1.52; GH20) and chitinase (EC 3.2.1.14; GH18), were compared. The common -1/+1 sugar-binding site of chitinase and OfHex1, and the -2/-3 sugar-binding site in chitinase contribute to the binding of allosamidin. This work, at molecular level, proved that OfHex1 could be a potential species-specific target for novel green pesticide design and also provide the possibility to develop allosamidin or its derivatives as a new type of insecticide to hit two birds with one stone, which maybe become a novel strategy in pest control.
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  • Crystal structure of human adenylate kinase 4 (L171P) suggests the role of hinge region in protein domain motion RID B-5001-2010 RID G-3306-2010

    Liu, Rujuan   Xu, Hang   Wei, Zhiyi   Wang, Yanli   Lin, Yajing   Gong, Weimin  

    It is well known that motion of LID and NMP-binding (NMP(bind)) domains in adenylate kinase (AK) is important in ligand binding and catalysis. However, the nature of such domain motions is poorly characterized. One of the Critical hinge regions is hinge IV, which connects the CORE and LID domains. In addition, the hinge IV contains a strictly conserved residue. L171, in the AK family. To investigate the role of hinge IV. crystal Structure Of human adenylate kinase 4 (AK4) L171 P Mutant was determined. This mutation dramatically changes the orientation of the LID domain, which could be described as a novel twisted- and-closed conformation in contrast to the open and closed conformations in other AKs. This mutant provides a new example of domain motions in AK family. (C) 2008 Elsevier Inc. All rights reserved.
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