4,043 research outputs found

    Demonstrating the model nature of the high-temperature superconductor HgBa2_2CuO4+Δ_{4+\Delta}

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    The compound HgBa2_2CuO4+Δ_{4+\Delta} (Hg1201) exhibits a simple tetragonal crystal structure and the highest superconducting transition temperature (Tc_c) among all single Cu-O layer cuprates, with Tc_c = 97 K (onset) at optimal doping. Due to a lack of sizable single crystals, experimental work on this very attractive system has been significantly limited. Thanks to a recent breakthrough in crystal growth, such crystals have now become available. Here, we demonstrate that it is possible to identify suitable heat treatment conditions to systematically and uniformly tune the hole concentration of Hg1201 crystals over a wide range, from very underdoped (Tc_c = 47 K, hole concentration p ~ 0.08) to overdoped (Tc_c = 64 K, p ~ 0.22). We then present quantitative magnetic susceptibility and DC charge transport results that reveal the very high-quality nature of the studied crystals. Using XPS on cleaved samples, we furthermore demonstrate that it is possible to obtain large surfaces of good quality. These characterization measurements demonstrate that Hg1201 should be viewed as a model high-temperature superconductor, and they provide the foundation for extensive future experimental work.Comment: 15 pages, 6 Figure

    Suppression of tobacco carcinogen-induced lung tumorigenesis by aerosol-delivered glycerol propoxylate triacrylate-spermine copolymer/short hairpin Rab25 rna complexes in female A/J mice

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    Background: Rab25, a member of Rab family of small guanosine triphosphatase, is associated with progression of various types of human cancers, including lung cancer, the leading cause of cancer-associated deaths around the globe. Methods: In this study, we report the gene therapeutic effect of short hairpin Rab25 RNA (shRab25) on 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumorigenesis in female A/J mice. Initially, mice (6 weeks old) were injected with single dose of NNK (2mg/0.1mL saline/mouse) by intraperitoneal injection to induce the tumor. Eight weeks later, shRab25 was complexed with glycerol propoxylate triacrylate-spermine (GPT-SPE) copolymer and delivered into tobacco-induced lung cancer models through a nose-only inhalation system twice a week for 2 months. Results: GPT-SPE/shRab25 largely decreased the tobacco-induced tumor numbers and tumor volume in the lungs compared to GPT-SPE- or GPT-SPE/shScr-delivered groups. Remarkably, aerosol-delivered GPT-SPE/shRab25 significantly decreased the expression level of Rab25 and other prominent apoptosis-related proteins in female A/J mice. The apoptosis in these mice was determined by detecting the expression level of Bcl-2, proliferating cell nuclear antigen, Bax, and further confirmed by TUNEL assay. Conclusions: Our results strongly confirm the tumorigenic role of Rab25 in tobacco carcinogen-induced lung cancer and hence demonstrate aerosol delivery of shRab25 as a therapeutic target for lung cancer treatment.

    Kinetics of cytokine expression in cirrhotic rats

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    AbstractBackgroundCytokines are involved in liver injury and cirrhosis and systemic and hepatic cytokine levels may help predict cirrhosis evolution. However, the relevant survey has not been performed.MethodsMale Sprague-Dawley rats (240–270g) received either common bile duct ligation (BDL, animal model of cholestatic liver injury) or sham operation (control). Five rats were sacrificed and liver and serum were collected from each in weeks 1, 2, 4, 6, 8 and 10 after surgery. Hepatic expression of interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10) and transforming growth factor-β (TGF-β) were analyzed by immunohistochemial staining. The corresponding serum levels were measured by ELISA.ResultsCompared to the corresponding sham groups, hepatic expression of these cytokines in BDL rats was significantly and progressively enhanced during cirrhosis development. However, serum IFN-γ levels of BDL rats did not change significantly. Serum TNF-α of BDL rats increased gradually and reached a peak in week 6. Serum TGF-β level was elevated up to week 8, whereas IL-10 level decreased progressively until week 6.ConclusionCirrhosis development in BDL rats is associated with progressively enhanced expression of hepatic pro-inflammatory and anti-inflammatory cytokines, which is not in accord with the corresponding serum concentration. The circulating cytokine concentration may not totally reflect the hepatic expression level throughout the development of cirrhosis

    降雨對南橫公路 50至110K 沿線山崩潛勢之影響

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    本研究蒐集中央地質調查所製作之2004 年敏督利颱風、2009 年莫拉克颱風及2011 年7 月19 日豪雨三場事件的事件型山崩目錄作為分析山崩組樣本,運用統計方法中的羅吉斯迴歸法建立潛在因子之山崩潛勢分析模式,首先初選高程類因子、坡度類因子、坡向、全坡高、岩性、地形粗糙度、坡度粗糙度、平面曲率、剖面曲率、總曲率、道路距、水系距等潛在因子,投入因子複選流程,篩選出不同事件下對於山崩鑑別能力較好的潛在因子。再加入各事件不同延時下的平均降雨強度作為誘發因子,將道路沿線之山崩潛勢值分為穩定、低、中及高崩塌潛勢區四個等級,探討降雨對於山崩潛勢分析的影響。整體結果顯示,於本研究山崩潛勢分析流程下,誘發因子的加入可增進模式對長延時高強度降雨型態 (如:莫拉克颱風事件) 的預測能力,針對中延時高強度與短延時中強度降雨型態模式,模式以潛在因子便足以維持一定的預測水準,誘發因子的加入對預測能力的提生並無顯著影響。This study uses the inventories of landslides during typhoon Mindulle, Morakot, and the 07/19 rainfall event established by Central Geological Survey as landslide data. The elevation, slope, slope aspect, slope high, lithology, terrain roughness, slope roughness, plan curvature, profile curvature, total curvature, distance from the road, and distance from the river are first chosen as the landslide causative factors, based on previous studies. Secondly, calibration and selection procedures are performed to efficiently select the factors. Logistic regression method is used to establish the landslide susceptibility model. Furthermore, the rainfall intensities of different rainfall durations are used as a landslide triggering factor in different rainfall events. The maps of potential landslides are delineated to discuss the influence of rainfall on landslide susceptibility analysis. The landslide susceptibilities are separated into four levels, including high, medium, low, and steady. According to the results, the model adopting the proposed rainfall factor increased the landslide predictive capability for long-duration and high-intensity rainfall events, such as the Morakot event. For the other two events, similar landslide predictive capabilities are obtained with and without applying the landslide causative factor in the model

    Probing Z' gauge boson with the spin configuration of top quark pair production at future ee+e^- e^+ linear colliders

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    We explore the effects of extra neutral gauge boson involved in the supersymmetric E6 model on the spin configuration of the top quark pair produced at the polarized e- e+ collider. Generic mixing terms are considered including kinetic mixing terms as well as mass mixing. In the off-diagonal spin basis of the standard model, we show that the cross sections for the suppressed spin configurations can be enhanced with the effects of the Z' boson through the modification of the spin configuration of produced top quark pair enough to be measured in the Linear Colliders, which provides the way to observe the effects of Z' boson and discriminate the pattern of gauge group decomposition. It is pointed out that the kinetic mixing may dilute the effects of mass mixing terms, and we have to perform the combined analysis.Comment: 19 pages including 5 figures, ReVTe

    Locally-applied 5-fluorouracil-loaded slow-release patch prevents pancreatic cancer growth in an orthotopic mouse model

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    To obtain improved efficacy against pancreatic cancer, we investigated the efficacy and safety of a locally-applied 5-fluorouracil (5-FU)-loaded polymeric patch on pancreatic tumors in an orthotopic nude-mouse model. The 5-FU-releasing polymeric patch was produced by 3D printing. After application of the patch, it released the drug slowly for 4 weeks, and suppressed BxPC-3 pancreas cancer growth. Luciferase imaging of BxPC3-Luc cells implanted in the pancreas was performed longitudinally. The drug patch delivered a 30.2 times higher level of 5-FU than an intra-peritoneal (i.p.) bolus injection on day-1. High 5-FU levels were accumulated within one week by the patch. Four groups were compared for efficacy of 5-FU. Drug-free patch as a negative control (Group I); 30% 5-FU-loaded patch (4.8 mg) (Group II); 5-FU i.p. once (4.8 mg) (Group III); 5-FU i.p. once a week (1.2 mg), three times (Group IV). The tumor growth rate was significantly faster in Group I than Group II, III, IV (p=0.047 at day-8, p=0.022 at day-12, p=0.002 at day-18 and p=0.034 at day-21). All mice in Group III died of drug toxicity within two weeks after injection. Group II showed more effective suppression of tumor growth than Group IV (p=0.018 at day-12 and p=0.017 at day-21). Histological analysis showed extensive apoptosis in the TUNEL assay and by Ki -67 staining. Western blotting confirmed strong expression of cleaved caspase-3 in Group II. No significant changes were found hematologically and histologically in the liver, kidney and spleen in Groups I, II, IV but were found in Group III.113Ysciescopu

    3D garment digitisation for virtual wardrobe using a commodity depth sensor

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    5-Aminovaleric acid (5AVA) is an important five-carbon platform chemical that can be used for the synthesis of polymers and other chemicals of industrial interest. Enzymatic conversion of L-lysine to 5AVA has been achieved by employing lysine 2-monooxygenase encoded by the davB gene and 5-aminovaleramidase encoded by the davA gene. Additionally, a recombinant Escherichia coli strain expressing the davB and davA genes has been developed for bioconversion of L-lysine to 5AVA. To use glucose and xylose derived from lignocellulosic biomass as substrates, rather than L-lysine as a substrate, we previously examined direct fermentative production of 5AVA from glucose by metabolically engineered E. coli strains. However, the yield and productivity of 5AVA achieved by recombinant E. coli strains remain very low. Thus, Corynebacterium glutamicum, a highly efficient L-lysine producing microorganism, should be useful in the development of direct fermentative production of 5AVA using L-lysine as a precursor for 5AVA. Here, we report the development of metabolically engineered C. glutamicum strains for enhanced fermentative production of 5AVA from glucose.Various expression vectors containing different promoters and origins of replication were examined for optimal expression of Pseudomonas putida davB and davA genes encoding lysine 2-monooxygenase and delta-aminovaleramidase, respectively. Among them, expression of the C. glutamicum codon-optimized davA gene fused with His-Tag at its N-Terminal and the davB gene as an operon under a strong synthetic H promoter (plasmid p36davAB3) in C. glutamicum enabled the most efficient production of 5AVA. Flask culture and fed-batch culture of this strain produced 6.9 and 19.7\ua0g/L (together with 11.9\ua0g/L glutaric acid as major byproduct) of 5AVA, respectively. Homology modeling suggested that endogenous gamma-aminobutyrate aminotransferase encoded by the gabT gene might be responsible for the conversion of 5AVA to glutaric acid in recombinant C. glutamicum. Fed-batch culture of a C. glutamicum gabT mutant-harboring p36davAB3 produced 33.1\ua0g/L 5AVA with much reduced (2.0\ua0g/L) production of glutaric acid.Corynebacterium glutamicum was successfully engineered to produce 5AVA from glucose by optimizing the expression of two key enzymes, lysine 2-monooxygenase and delta-aminovaleramidase. In addition, production of glutaric acid, a major byproduct, was significantly reduced by employing C. glutamicum gabT mutant as a host strain. The metabolically engineered C. glutamicum strains developed in this study should be useful for enhanced fermentative production of the novel C5 platform chemical 5AVA from renewable resources

    Introducing PHAEDRA: a new spectral code for simulations of relativistic magnetospheres

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    We describe a new scheme for evolving the equations of force-free electrodynamics, the vanishing-inertia limit of magnetohydrodynamics. This pseudospectral code uses global orthogonal basis function expansions to take accurate spatial derivatives, allowing the use of an unstaggered mesh and the complete force-free current density. The method has low numerical dissipation and diffusion outside of singular current sheets. We present a range of one- and two-dimensional tests, and demonstrate convergence to both smooth and discontinuous analytic solutions. As a first application, we revisit the aligned rotator problem, obtaining a steady solution with resistivity localised in the equatorial current sheet outside the light cylinder.Comment: 23 pages, 18 figures, accepted for publication in MNRA

    Ginseng on Hyperglycemia: Effects and Mechanisms

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    It has been reported that American ginseng attenuates hyperglycemia and may present itself as a supplement to diabetes therapy. However, the lack of standardization in the usage of ginseng root leads to inconclusive results when applied to diabetes treatment. The mechanisms of American ginseng root in the treatment of diabetes remains a mystery. This greatly limits the effective utilization of American ginseng in facilitating diabetic therapy. Initiating studies have shown that American ginseng increases insulin production and reduces cell death in pancreatic β-cells. Also, studies have revealed American ginseng's ability to decrease blood glucose in type II diabetes patients as well as in streptozotocin-induced diabetic animals (STZ-diabetic mice). These data suggest that effects of ginseng in improving hyperglycemia may alter mitochondrial function as well as apoptosis cascades to ensure cell viability in pancreatic islet cells. This review briefly summarizes current knowledge of ginseng components and clinical studies related to diabetes. Further research will be needed to explore and identify the component(s) of ginseng, which may be responsible for the beneficial effects observed in animal studies which could then be extrapolated to human islets
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