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Now showing items 129 - 144 of 446

  • Large Area Synthesis of 1D-MoSe2 Using Molecular Beam Epitaxy

    Poh, Sock Mui   Tan, Sherman J. R.   Zhao, Xiaoxu   Chen, Zhongxin   Abdelwahab, Ibrahim   Fu, Deyi   Xu, Hai   Bao, Yang   Zhou, Wu   Loh, Kian Ping  

    Large area synthesis of 1D-MoSe2 nano-ribbons on both insulating and conducting substrates via molecular beam epitaxy is presented. Dimensional controlled growth of 2D, 1D-MoSe2, and 1D-2D-MoSe2 hybrid heterostructure is achieved by tuning the growth temperature or Mo:Se precursor ratio.
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  • Solution-Processed Sensing Textiles with Adjustable Sensitivity and Linear Detection Range Enabled by Twisting Structure

    Hui, Zengyu   Chen, Ruyi   Chang, Jin   Gong, Yujiao   Zhang, Xianwang   Xu, Hai   Sun, Yue   Zhao, Yue   Wang, Lumin   Zhou, Ruicong   Ju, Feng   Chen, Qiang   Zhou, Jinyuan   An, Jianing   Sun, Gengzhi   Huang, Wei  

    Wearable strain sensors are emerging rapidly for their promising applications in human motion detection for diagnosis, healthcare, training instruction, and rehabilitation exercise assessment. However, it remains a bottleneck in gaining comfortable and breathable devices with the features of high sensitivity, linear response, and tunable detection range. Textiles possess fascinating advantages of good breathability, aesthetic property, tailorability, and excellent mechanical compliance to conformably attach to human body. As the meandering loops in a textile can be extended in different directions, it provides plenty of room for exploring ideal sensors by tuning a twisting structure with rationally selected yarn materials. Herein, textile sensors with twisting architecture are designed via a solution-based process by using a stable water-based conductive ink that is composed of polypyrrole/polyvinyl alcohol nanoparticles with a mean diameter of 50 nm. Depending on the predesigned twisting models, the thus-fabricated textile sensors show adjustable performances, exhibiting a high sensitivity of 38.9 with good linearity and a broad detection range of 200%. Such sensors can be integrated into fabrics and conformably attached to skin for monitoring subtle (facial expressions, breathing, and speaking) and large (stretching, jumping, running and jogging, and sign language) human motions. As a proof-of-concept application, by integrating with a wireless transmitter, the signals detected by our sensors during exercise (e.g., running) can be remotely received and displayed on a smartphone. It is believed that the integration of our textile sensors with selected twisting models into a cloth promises full-range motion detection for wearable electronics and human-machine interfaces.
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  • Effects of Conventional Surfactants on the Activity of Designed Antimicrobial Peptide

    Liu, Kang   Yang, Liuxin   Peng, Xiaoting   Gong, Haoning   Wang, Jiqian   Lu, Jian Ren   Xu, Hai  

    In this article, the interaction between a designed antimicrobial peptide (AMP) G(IIKK)(3)I-NH2 (G(3)) and four typical conventional surfactants (sodium dodecyl sulfonate (SDS), hexadecyl trimethyl ammonium bromide (C(16)TAB), polyoxyethylene (23) lauryl ether (C12EO23), and tetradecyldimethylamine oxide (C(14)DMAO)) has been studied through surface tension measurement and circular dichroism (CD) spectroscopy. The antimicrobial activities of AMP/surfactant mixtures have also been studied with Gram-negative Escherichia coli, Gram-positive Staphylococcus aureus, and the fungus Candida albicans. The cytotoxicity of the AMP/surfactant mixtures has also been assessed with NIH 3T3 and human skin fibroblast (HSF) cells. The surface tension data showed that the AMP/SDS mixture was much more surface-active than SDS alone. CD results showed that G(3) conformation changed from random coil, to beta-sheet, and then to a-helix with increasing SDS concentration, showing a range of structural transformation driven by the different interactions with SDS. The antimicrobial activity of G(3) to Gram-negative and Gram-positive bacteria decreased in the presence of SDS due to the strong interaction of electrostatic attraction between the peptide and the surfactant. The interactions between G(3) and C(16)TAB, C12EO23, and C(14)DMAO were much weaker than SDS. As a result, the surface tension of surfactants with G(3) did not change much, neither did the secondary structures of G(3). The antimicrobial activities of G(3) were little affected in the presence of C12EO23, slightly improved by C(14)DMAO, and clearly enhanced by cationic surfactant C(16)TAB due to its strong cationic and antimicrobial nature, consistent with their surface physical activities as binary mixtures. Although AMP G(3) did not show activity to fungus, the mixtures of AMP/C(16)TAB and AMP/C(14)DMAO could kill C. albicans at high surfactant concentrations. The mixtures had rather high cytotoxicity to NIH 3T3 and HSF cells although G(3) is nontoxic to cells. Cationic AMPs can be formulated with nonionic, cationic, and zwitterionic surfactants during product development, but care must be taken when AMPs are formulated with anionic surfactants, as the strong electrostatic interaction may undermine their antimicrobial activity.
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  • Interaction of fluorescence labeled single-stranded DNA with hexameric DNA-helicase RepA: A photon and fluorescence correlation spectroscopy study

    Xu, Hai   Frank, Joachim   Trier, Ulrike   Hammer, Stefanie   Schroeder, Werner   Behlke, Joachim   Schaefer-Korting, Monika   Holzwarth, Josef F.   Saenger, Wolfram  

    Fluorescence correlation spectroscopy (FCS) was used to characterize the interaction of fluorescence labeled single-stranded DNA (ssDNA) with hexameric RepA DNA-helicase (hRepA) encoded by plasmid RSF1010. The apparent dissociation constants, Kd(app), for the equilibrium binding of 12mer, 30mer, and 45mer ssDNA 5'-labeled with BFL to hRepA dimer in the presence of 0.5 mM ATPgammaS at pH 5.8 and 25 degreeC were determined to be 0.58+-0.12, 0.52+-0.07, and 1.66+-0.32 muM, respectively. Binding curves are compatible with one binding site for ssDNA present on hRepA dimer, with no indication of cooperativity. At pH 7.6 in the presence of ATPgammaS and at pH 5.8 in the absence of ATPgammaS, complex formation between ssDNA and hRepA was too weak for measuring complete binding curves by FCS. Under these conditions, the dissociation constant, Kd(app), is in the range between 10 and 250 muM. The kinetics of complex formation at pH 5.8 are faster than the time resolution (approximately 10-20 s) of FCS experiments under pseudo-first-order conditions, with respect to BFL-ssDNA. Photon correlation spectroscopy (PCS) experiments yielded, within the experimental error range, the same values for the apparent hydrodynamic radii, Rh, of hRepA dimer and its complex with ssDNA as determined by FCS (Rh=6.6+-1 nm). hRepA starts to aggregate under acidic conditions (
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  • Interfacial assembly of cationic peptide surfactants RID A-1690-2011

    Zhao, XiuBo   Pan, Fang   Perumal, Shiamalee   Xu, Hai   Lu, Jian R.   Webster, John R. P.  

    Short surfactant-like peptides bearing the molecular architecture of hydrophilic and hydrophobic moieties are attractive for a wide range of biological and technological applications. However, to realize the benefits offered by them we need to understand the basic physiochemical properties arising from their interfacial self-assembly and solution aggregation. In this paper, we use a combined approach of spectroscopic ellipsometry (SE), atomic force microscopy (AFM) and neutron reflection (NR) to characterize the interfacial assembly of cationic peptide V(6)K(2) at the hydrophilic silica-water interface. The SE measurement revealed that the peptide dynamic adsorption was characterised by a fast initial process within the first 3-5 min, followed by a slow molecular reorientation within the next 30-40 min. AFM imaging revealed the formation of a dense peptide layer incorporating defects and some large vesicles. This interfacial structural feature from AFM offered a useful starting point for fitting the neutron reflectivity profiles measured. At 0.05 wt% V(6)K(2), the reflectivity profiles were well fitted using a two-layer model with a dense 40 angstrom inner layer containing about 50% peptide close to the oxide surface and a loose 40 angstrom outer layer containing some 8% peptide on the solution side. With the help of partial deuteration to the peptide (hV(6)hK(2) and dV(6)hK(2) and the solvent isotopic contrasts (D(2)O, H(2)O), we found that the densely packed peptide region was comprised of a sandwiched peptide bilayer with their hydrophobic tails (V(6)) attracted to each other and the cationic head groups (K(2)) projected towards the oxide surface and the bulk water. This peptide bilayer structure is similar to that formed by conventional cationic surfactants when adsorbed at the same anionic SiO(2)-water interface, indicating the dominant effect of hydrophobic interaction. This study has demonstrated that the combined measurements provide a useful account of structure and dynamics of interfacial peptide self-assembly.
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  • Unusual life-threatening Rosai-Dorfman disease of the trachea: role of NF-kappa B

    Zhou, Lin-Fu   Chen, Liang   Zhu, Quan   Wang, Cong   Xu, Hai   Cui, Xue-Fan   Jiang, Lei-Fu   He, Shao-Heng   Huang, Mao   Yin, Kai-Sheng  

    RosaieDorfman disease (RDD) is a rare non-neoplastic histioproliferative disorder characterised by painless lymphadenopathy, low fever, high erythrocyte sedimentation rate, leucocytosis and hypergammaglobulinaemia. Overactivity of nuclear factor kappa B (NF-kappa B) is linked with inflammatory, cancerous and autoimmune diseases. The first case is described of an unusual life-threatening RDD of the trachea with no lymphadenopathy at risk of suffocation in a 39-year-old Chinese woman. A diagnosis of RDD was made following CT scans, thoracotomy and histological examination. Gel shift assay revealed an essential role for NF-kappa B overactivity in RDD. The patient remains well with no evidence of progression without treatment. Histological confirmation should be sought in all cases as the clinical manifestation of RDD is similar to asthma or lung carcinoma.
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  • Aggregation-induced emission fluorescent probe for monitoring endogenous alkaline phosphatase in living cells

    Li, Yaqian   Xie, Ruihua   Pang, Xiao   Zhou, Zile   Xu, Hai   Gu, Biao   Wu, Cuiyan   Li, Haitao   Zhang, Youyu  

    Alkaline phosphatase (ALP) is a non-specific phosphate monoesterase and often regarded as an important biomarker of hypothyroidism and hepatobiliary diseases in medical diagnosis. In-situ detection of endogenous ALP and exploration of the distribution of ALP in cells are of great importance for the diagnosis of diseases associated with ALP. In this work, we designed and synthesized an aggregation-induced emission (AIE) fluorescent probe, (E)-2-(((9H-fluoren-9-ylidene) hydrazono)methyl)phenyl dihydrogen phosphate (FAS-P), that can respond to ALP with a remarkable large Stokes shift ( > 200 nm) based on excited state intramolecular proton transfer (ESIPT) mechanism. The probe FAS-P has high selectivity and sensitivity to the detection of ALP. And there is a linear relationship between the fluorescence intensity of FAS-P and ALP activity in the range of 1-100 U L-1, the limit of detection (LOD) is as low as 0.6 U L-1. More importantly, we successfully applied FAS-P to detect ALP in living cells and the monitoring of ALP in real time.
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  • Using Bispyrene Fluorescence Probe for Determining the Multiple States of Organogel

    Liang, Yong   Tang, Jun   Wang, Xiang   Zhao, Siqi   Luo, Ting   Shuai, Cijun   Jiang, Jinzhi   Cai, Jianfeng   Xu, Hai  

    A bispyrene fluorescence probe with the cavitand linkage (compound 1) was synthesized, which was proved to be a versatile platform due to the ability of adopting two spatially well-defined conformations: a closed vase and an expanded kite. vase-1 was switched to kite-1 upon addition of TFA or cooling, whereas kite-1 was isomerized to vase-1 in the presence of NEt3 or through heating. The interconversion in this molecular switch was tightly associated with the change of fluorescence as we found that changing the temperature and pH of the system- a bis pyrene compound 1 and gelator 2 led to the sol - gel transformation and reversible intramolecular excimer emission. Briefly, the results show that the fluorescence decreases in the gelation phase and is enhanced in the solution due to variations in temperature and pH. we thus concluded that 1 could be a useful fluorescence probe to determine the multiple states of organogel.
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  • Design and Synthesis of Oligoamide-Based Double -Helix Mimetics

    Kulikov, Oleg V.   Thompson, Sam   Xu, Hai   Incarvito, Christopher D.   Scott, Richard T. W.   Saraogi, Ishu   Nevola, Laura   Hamilton, Andrew D.  

    An extensive series of bis-oligobenzamides and bis-oligopyridylamides have been efficiently prepared and studied by X-ray analysis and computational methods. A modular synthesis led to double -helix mimics bearing between two and ten branched side-chains. The inter-helix angle and distance can be tuned by varying the length and rigidity of the spacer, thereby reproducing the recognition domains of a range of super-secondary structures.
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  • A two-component active targeting theranostic agent based on graphene quantum dots

    Wang, Xiaojuan   Sun, Xing   He, Hua   Yang, Hao   Lao, Jun   Song, Yanzhuo   Xia, Yongqing   Xu, Hai   Zhang, Xiaodong   Huang, Fang  

    Using nanotechnology, therapeutics can be combined with diagnostics for cancer treatment. To do this, a targeting ligand, an imaging contrast agent and an anti-tumour therapeutic agent were the minimum requirements for active targeting nanoassemblies. Here we have developed a novel active targeting theranostic agent, made up of just two components, aptamer AS1411 and graphene quantum dots (GQDs). Each component in our agent plays multiple roles. Confocal microscopy using a 488 nm laser shows that this agent has an excellent capability to label tumour cells selectively. On the therapeutic side, this agent induced a synergistic growth inhibition effect towards cancer cells when irradiated with a near infrared laser of 808 nm. The ultra-small size, good biocompatibility, intrinsic stable fluorescence, and near-infrared response character make GQDs a remarkable constituent to build theranostic agents.
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  • Nanoribbons self-assembled from short peptides demonstrate the formation of polar zippers between beta-sheets.

    Wang, Meng   Wang, Jiqian   Zhou, Peng   Deng, Jing   Zhao, Yurong   Sun, Yawei   Yang, Wei   Wang, Dong   Li, Zongyi   Hu, Xuzhi   King, Stephen M   Rogers, Sarah E   Cox, Henry   Waigh, Thomas A   Yang, Jun   Lu, Jian Ren   Xu, Hai  

    Peptide self-assembly is a hierarchical process, often starting with the formation of alpha-helices, beta-sheets or beta-hairpins. However, how the secondary structures undergo further assembly to form higher-order architectures remains largely unexplored. The polar zipper originally proposed by Perutz is formed between neighboring beta-strands of poly-glutamine via their side-chain hydrogen bonding and helps to stabilize the sheet. By rational design of short amphiphilic peptides and their self-assembly, here we demonstrate the formation of polar zippers between neighboring beta-sheets rather than between beta-strands within a sheet, which in turn intermesh the beta-sheets into wide and flat ribbons. Such a super-secondary structural template based on well-defined hydrogen bonds could offer an agile route for the construction of distinctive nanostructures and nanomaterials beyond beta-sheets.=20
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  • Responses of cyanobacteria to climate and human activities at Lake Chenghai over the past 100 years

    Yan, Dongna   Xu, Hai   Yang, Ming   Lan, Jianghu   Hou, Weiguo   Wang, Fushun   Zhang, Jixiao   Zhou, Kangen   An, Zhisheng   Goldsmith, Yonaton  

    Cyanobacteria play important roles in carbon and nutrient cycling in aquatic systems. Cyanobacteria biomass in most lakes has increased over recent decades, threatening both water quality and ecosystem management. However, due to lack of long-term monitoring, the factors that control the interannual variability and diversity of cyanobacteria are poorly known. In this study, we used genetics and geochemical record of a vertical-down sediment core to investigate the impacts of climate changes and human activities on the long-term (100-year) abundance and diversity of cyanobacteria at Lake Chenghai, southwestern China. The results show that before 1980 CE, the nutrient level of Lake Chenghai was in a generally natural state, and human impacts were relatively weak; whereas after 1980 CE the cyanobacterial biomass inferred from both qPCR and Miseq sequencing have significantly increased compared with the average of the past 100 years, suggesting that major changes in both human activities and hydrological conditions might have occurred since then. The phosphorus (P) concentration and lake level changes are thought to have significant impacts on the cyanobacterial biomass in this lake. We contend that both human activities and the decrease in lake water level (which could lead to enrichment of nutrients in the water) could have resulted in an increase in cyanobacterial biomass and total phosphorus (TP) in lake sediments. The results of this study suggest that controls on nutrient inputs and lake levels are necessary to ensure the sustainability of Lake Chenghai, especially under a continuous global warming scenario.
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  • Hydrothermal synthesis of ultrafine beta-FeOOH nanorods as cathode materials for lithium ion batteries

    Zhou, Fu   Zhao, Xuemei   Yuan, Cunguang   Xu, Hai  

    beta-FeOOH nanorods with the diameter of only 10 nm were fabricated through a facile PEG-assisted hydrothermal synthetic route, which was the smallest dimension reported for the fabrication of beta-FeOOH one-dimensional (1-D) nanostructures so far. The as-prepared ultrafine beta-FeOOH nanorods were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and galvanostatic tests. Electrochemical tests on the as-obtained ultrafine beta-FeOOH nanorods revealed that they exhibited excellent electrochemical properties with a large discharge capacity of 290 mA h g(-1) and good cycleability, which enabled them to be applied as superior cathode materials for lithium ion battery systems.
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  • An SFL approach to gender ideology in the sentence examples in the Contemporary Chinese Dictionary

    Hu, Huilian   Xu, Hai   Hao, Junjie  

    This study concerns the gender ideology reflected by dictionary examples. It mainly used the transitivity and interpersonal systems in Systemic Functional Linguistics to analyze the gender discourse in the seventh edition of the Contemporary Chinese Dictionary (CCD7). The analysis reveals certain differences between the transitivity patterns and interpersonal meaning of female- and male-related sentence examples from the A-B sections of CCD7. Women's experiences are mostly confined to themselves and their adjacent environment. Their actions are often self-directed, seldom affecting other participants or the environment. In contrast, men are usually portrayed as the typical social men, active social participants, and shapers of the environment, whose actions often bring concrete changes to other participants or to the environment. The differences between transitivity patterns and interpersonal meaning construct men as valuable social members while overlooking the due value of women in the social world. (C) 2018 Elsevier B.V. All rights reserved.
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  • Preoperative CT Predicting Recurrence of Surgically Resected Adenocarcinoma of the Lung

    Koo, Hyun Jung   Xu, Hai   Choi, Chang-Min   Song, Joon Seon   Kim, Hyeong Ryul   Lee, Jung Bok  

    Pathologic lymphovascular invasion (LVI) has been shown to be related to tumor recurrence in lung adenocarcinoma (ADC). We investigated preoperative computed tomography (CT) findings that may be related to pathologic LVI and recurrence of surgically managed stage I-II ADC of the lung.Consecutive patients (n =3D 275) with ADC from January 2013 to December 2013 were retrospectively enrolled. Two independent chest radiologists analyzed the CT findings. Clinical, CT (stage, margin, pleural tag, axial location, and peritumoral interstitial thickening), and pathologic findings (stage, % lepidic growth, and LVI) were reviewed. Cox proportional hazard regression analysis was used to estimate the hazard ratios (HRs) for patients with (n =3D 34) and without (n =3D 241) recurrence.The kappa index for agreement on the CT findings between radiologists was 0.705 to 0.845. In univariate analysis, % lepidic growth (P =3D 0.006), LVI (P < 0.001), size (P < 0.001), and staging (P =3D 0.011) differentiated significantly between patients with and without recurrence. Long diameter (P < 0.001), mass type (P < 0.001), marginal lobulation (P =3D 0.020), central location (P < 0.001), and peritumoral interstitial thickening (P < 0.001) were significantly related to recurrence on CT. Peritumoral interstitial thickening was positively correlated with tumor size (P < 0.001), LVI (P < 0.001), N staging (P =3D 0.005), stage (P < 0.001), mass type (P < 0.001), and recurrence (P =3D 0.003). In multivariate analysis, size (HR, 1.052; 95% CI, 1.022-1.082; P < 0.001), central location (HR, 3.152; 1.387-7.166; P =3D 0.006), and LVI (HR, 2.153, 95% CI, 1.038-4.465; P =3D 0.039) were independent predictors of recurrence.Large, centrally located tumors with LVI tend to recur after surgery. Presence of peritumoral interstitial thickening on CT appears to predict pathologic LVI and recurrence.
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  • De novo transcriptome sequencing of pakchoi (Brassica rapa L. chinensis) reveals the key genes related to the response of heat stress

    Xu, Hai   Chen, Longzheng   Song, Bo   Fan, Xiaoxue   Yuan, Xihan  

    Pakchoi is an important vegetable grown in worldwide that prefers a cool climate, and its growth is severely affected by high temperatures in the summer. Little is known for the molecular regulatory mechanisms of high-temperature stress in pakchoi. The limited availability of gene sequence has greatly affected molecular breeding and functional genomic analysis. In this study, we conducted comprehensive analyses for heat treatment in pakchoi by RNA-Seq. Finally, 64.29 million clean reads containing 32,666 unigenes with an N50 length of 1405 bp, and a total length of 33.39 Mb were identified. Overall, 11,024 SSRs located in 8404 unigenes were obtained; these findings will be very useful for molecular assisted breeding. Totally, 1220 differentially expressed genes (DEGs) were detected between the high-temperature group (TH) and the control (CK), among which 699 DEGs were upregulated and 521 were down-regulated. The enrichment analysis indicated that 12 GO subcategories and 9 KEGG pathways were enriched significantly (P value <0.05). Finally, six DEGs were validated by qRT-PCR, and the results further verified the reliability of RNA-Seq. Herein, we present the first comprehensive characterization of heat-treated pakchoi using transcriptome analysis. Several important genes that respond to high temperature were identified, and their roles in heat stress responses are discussed. In conclusion, our study represents a fully characterised pakchoi transcriptome. In addition, it provides the important resources for future genomic and genetic studies of pakchoi under heat stress.
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