3,872 research outputs found

    A novel base station antenna based on rectangular waveguide

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    © 2016 IEICE. A novel base station antenna element is proposed. It consists of a surface of parallel strips to rotate the polarization direction and a segment of a rectangular waveguide. The surface is designed on a single-sided substrate, which has the same area as the aperture of the waveguide. In assembling, the non-copper side of the substrate is placed in direct contact with the aperture of the waveguide antenna. To achieve the polarization rotation, the parallel strips on the surface are rotated by 45° with respect to the walls of the waveguide antenna. By adding the surface, the linear polarization direction of the rectangular waveguide antenna is rotated by 45° to comply with the requirements of cellular industry. SMA connector with a conical probe is used as the coaxial-to-waveguide adaptor. Results have shown that the proposed antenna has a fractional impedance bandwidth of 35%, and a stable radiation pattern is also achieved

    Development of a novel forward dynamic programming method for weather routing

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    This paper presents a novel forward dynamic programming method for weather routing to minimise ship fuel consumption during a voyage. Compared with traditional weather routing methods which only optimise the ship's heading, while the engine power or propeller rotation speed is set as a constant throughout the voyage, this new method considers both the ship power settings and heading controls. A float state technique is used to reduce the iterations required during optimisation and thus save computation time. This new method could lead to quasiglobal optimal routing in comparison with the traditional weather routing methods

    Gate controlled electronic transport in monolayer MoS2 field effect transistor

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    Polarization-Rotated Waveguide Antennas for Base-Station Applications

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    © 2017 IEEE. A novel base-station antenna element is proposed. It consists of an artificial surface composed of parallel strips rotating in the polarization direction and a segment of a rectangular waveguide. The surface is designed on a single-sided substrate, which has the same area as the aperture of the waveguide. To achieve the polarization rotation, the parallel strips on the surface are rotated by 45° with respect to the orientation of the waveguide antenna. By adding the surface, the linear polarization direction of the rectangular waveguide antenna rotates by 45° to comply with the requirements of the cellular industry. To verify the simulation results, the proposed antenna was fabricated and measured. Results show that the antenna has an operating bandwidth from 698-960 MHz, where a stable radiation pattern is achieved

    Significance of CO2 donor on the production of succinic acid by Actinobacillus succinogenes ATCC 55618

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    <p>Abstract</p> <p>Background</p> <p>Succinic acid is a building-block chemical which could be used as the precursor of many industrial products. The dissolved CO<sub>2 </sub>concentration in the fermentation broth could strongly regulate the metabolic flux of carbon and the activity of phosphoenolpyruvate (PEP) carboxykinase, which are the important committed steps for the biosynthesis of succinic acid by <it>Actinobacillus succinogenes</it>. Previous reports showed that succinic acid production could be promoted by regulating the supply of CO<sub>2 </sub>donor in the fermentation broth. Therefore, the effects of dissolved CO<sub>2 </sub>concentration and MgCO<sub>3 </sub>on the fermentation process should be investigated. In this article, we studied the impacts of gaseous CO<sub>2 </sub>partial pressure, dissolved CO<sub>2 </sub>concentration, and the addition amount of MgCO<sub>3 </sub>on succinic acid production by <it>Actinobacillus succinogenes </it>ATCC 55618. We also demonstrated that gaseous CO<sub>2 </sub>could be removed when MgCO<sub>3 </sub>was fully supplied.</p> <p>Results</p> <p>An effective CO<sub>2 </sub>quantitative mathematical model was developed to calculate the dissolved CO<sub>2 </sub>concentration in the fermentation broth. The highest succinic acid production of 61.92 g/L was obtained at 159.22 mM dissolved CO<sub>2 </sub>concentration, which was supplied by 40 g/L MgCO<sub>3 </sub>at the CO<sub>2 </sub>partial pressure of 101.33 kPa. When MgCO<sub>3 </sub>was used as the only CO<sub>2 </sub>donor, a maximal succinic acid production of 56.1 g/L was obtained, which was just decreased by 7.03% compared with that obtained under the supply of gaseous CO<sub>2 </sub>and MgCO<sub>3</sub>.</p> <p>Conclusions</p> <p>Besides the high dissolved CO<sub>2 </sub>concentration, the excessive addition of MgCO<sub>3 </sub>was beneficial to promote the succinic acid synthesis. This was the first report investigating the replaceable of gaseous CO2 in the fermentation of succinic acid. The results obtained in this study may be useful for reducing the cost of succinic acid fermentation process.</p

    Design and Testing of Cesium Atomic Concentration Detection System Based on TDLAS

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    In order to better build the Neutral Beam Injector with Negative Ion Source (NNBI), the pre-research on key technologies has been carried out for the Comprehensive Research Facility for Fusion Technology (CRAFT). Cesium seeding into negative-ion sources is a prerequisite to obtain the required negative hydrogen ion. The performance of ion source largely depends on the cesium conditions in the source. It is very necessary to quantitatively measure the amount of cesium in the source during the plasma on and off periods (vacuum stage). This article uses the absorption peak of cesium atoms near 852.1nm to build a cesium atom concentration detection system based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology. The test experiment based on the cesium cell is carried out, obtained the variation curve of cesium concentration at different temperatures. The experimental results indicate that: the system detection range is within 5*10E6-2.5*10E7 pieces/cm3 and the system resolution better than 1*10E6 pieces/cm3.Comment: 8 pages,7 figures, the 20th International Symposium on Laser-Aided Plasma Diagnostic

    Small-Molecule Synthetic Compound Norcantharidin Reverses Multi-Drug Resistance by Regulating Sonic Hedgehog Signaling in Human Breast Cancer Cells

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    Multi-drug resistance (MDR), an unfavorable factor compromising treatment efficacy of anticancer drugs, involves upregulated ATP binding cassette (ABC) transporters and activated Sonic hedgehog (Shh) signaling. By preparing human breast cancer MCF-7 cells resistant to doxorubicin (DOX), we examined the effect and mechanism of norcantharidin (NCTD), a small-molecule synthetic compound, on reversing multidrug resistance. The DOX-prepared MCF-7R cells also possessed resistance to vinorelbine, characteristic of MDR. At suboptimal concentration, NCTD significantly inhibited the viability of DOX-sensitive (MCF-7S) and DOX-resistant (MCF-7R) cells and reversed the resistance to DOX and vinorelbine. NCTD increased the intracellular accumulation of DOX in MCF-7R cells and suppressed the upregulated the mdr-1 mRNA, P-gp and BCRP protein expression, but not the MRP-1. The role of P-gp was strengthened by partial reversal of the DOX and vinorelbine resistance by cyclosporine A. NCTD treatment suppressed the upregulation of Shh expression and nuclear translocation of Gli-1, a hallmark of Shh signaling activation in the resistant clone. Furthermore, the Shh ligand upregulated the expression of P-gp and attenuated the growth inhibitory effect of NCTD. The knockdown of mdr-1 mRNA had not altered the expression of Shh and Smoothened in both MCF-7S and MCF-7R cells. This indicates that the role of Shh signaling in MDR might be upstream to mdr-1/P-gp, and similar effect was shown in breast cancer MDA-MB-231 and BT-474 cells. This study demonstrated that NCTD may overcome multidrug resistance through inhibiting Shh signaling and expression of its downstream mdr-1/P-gp expression in human breast cancer cells

    Dramatic escalation in metabolic syndrome and cardiovascular risk in a Chinese population experiencing rapid economic development

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    Background Metabolic syndrome (MetSyn) increases the incidence of cardiovascular disease. Information on changes in prevalence of MetSyn in developing countries is limited. This study aims to compare MetSyn prevalence and its associated vascular risk over the period between 2002 and 2010 in a population which has had the world’s fastest economic development over the past three decades. Methods Two health surveys were conducted by using the multistage cluster random sampling method in a Chinese population of 85 million in southern China. The participants received a full medical check-up, including measurement of blood pressure (BP), obesity indices, fasting lipids and glucose levels. Data describing socio-economic status and lifestyle factors were also collected through interview. Metabolic syndrome was defined in accordance with the International Diabetes Federation criteria. Results A total of 3,561 participants from Survey 2010 were included in the data analysis. Women had a significantly higher prevalence of MetSyn than men. Comparison between the two surveys shows that age-standardized prevalence of MetSyn increased fourfold (from 5.4% in 2002 to 21.3% in 2010) in those ≧ 20 years. Among the MetSyn components, prevalence of hyperglycaemia has increased most (from 9.1% to 53.1%). The age-standardized prevalence of central obesity, hypertension, hypertriglyceridaemia and low HDL-cholesterol increased from 13.5% to 25.4%, from 23.6% to 40.8%, from 12.1% to 17.4% and from 32.1% to 71.1%, respectively. Differences between rural and urban residents in the prevalence in MetSyn and its components narrowed in 2010. Conclusions Cardiovascular risk escalated dramatically in this population between 2002 and 2010. The escalation may relate to the rapid economic development, which led to accelerating changes in nutrition, lifestyle, and socio-economic status. Our findings suggest that health transition in rapidly developing second- and third-world countries may be much faster than what has been observed in Western countries.published_or_final_versio

    7,8-dihydroxy-3-methyl-10-oxo-1H,10H-pyrano[4,3-b]chromene-9-carboxylic acid

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    The structure of the title compound, anhydrofulvic acid, C14H10O7, a yellow acidic metabolite isolated from Paecilomyces sp. was determined by X-ray analysis. The chromone ring system is essentially planar, with the carboxylic acid group coplanar with the ring
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