1,533 research outputs found

    Printed spiral winding inductor with wide frequency bandwidth

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    Winding parasitic capacitance is a major factor limiting the bandwidth of an inductor. In this paper, 1) the traditional, 2) the alternating, and 3) the partial alternating winding methods are evaluated for the multilayer printed spiral winding inductors for megahertz operations. The self-capacitances of various winding structures are estimated by the summation of parasitic capacitance among the turns of a winding. The electric field energy distributions in the inductors are derived from the voltage profiles to illustrate the relative magnitudes of winding parasitic capacitances. The results show that parasitic capacitance reduction can be achieved by reducing stored electric field energy. The partial alternating winding method is found to have the widest frequency bandwidth with reduced number of through-hole vias for multilayer printed spiral winding design. The theoretical analysis has been confirmed with practical measurements. The results provide useful information for the optimal design of coreless or core-based high-frequency planar magnetics. © 2011 IEEE.published_or_final_versio

    Assessment of vibrations induced in factories by automated guided vehicles

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    Ultrasound volume projection image quality selection by ranking from convolutional RankNet.

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    Periodic inspection and assessment are important for scoliosis patients. 3D ultrasound imaging has become an important means of scoliosis assessment as it is a real-time, cost-effective and radiation-free imaging technique. With the generation of a 3D ultrasound volume projection spine image using our Scolioscan system, a series of 2D coronal ultrasound images are produced at different depths with different qualities. Selecting a high quality image from these 2D images is the crucial task for further scoliosis measurement. However, adjacent images are similar and difficult to distinguish. To learn the nuances between these images, we propose selecting the best image automatically, based on their quality rankings. Here, the ranking algorithm we use is a pairwise learning-to-ranking network, RankNet. Then, to extract more efficient features of input images and to improve the discriminative ability of the model, we adopt the convolutional neural network as the backbone due to its high power of image exploration. Finally, by inputting the images in pairs into the proposed convolutional RankNet, we can select the best images from each case based on the output ranking orders. The experimental result shows that convolutional RankNet achieves better than 95.5% top-3 accuracy, and we prove that this performance is beyond the experience of a human expert

    A Compact Design Using GaN Semiconductor Devices for a Flying Capacitor Five-Level Inverter

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    Multilevel inverters (MLIs) based on the flying capacitor (FC) concept are beneficial in many renewable energy-based applications due to their compactness, low current stress on semiconductor devices, and reasonable thermal behavior for high-power applications. However, the recently developed FC-based topologies suffer from half dc-link voltage utilization and a variable high-frequency common-mode voltage (HF-CMV). The aim of this paper is to propose an FC-based family of MLIs with a five-level (5L) output voltage, full dc-link voltage utilization, and low HF-CMV. Using redundant states and the phase-shifted sinusoidal PWM technique, the value of the flying capacitor has been reduced significantly. The performance of the converter has been verified using Gallium Nitride (GaN) power switches. Circuit description and a brief comparative study with existing MLIs are given to justify the suitability of the topology

    Construction and Characterization of Two Bacterial Artificial Chromosome Libraries of Grass Carp

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    Bacterial artificial chromosome (BAC) library is an important tool in genomic research. We constructed two libraries from the genomic DNA of grass carp (Ctenopharyngodon idellus) as a crucial part of the grass carp genome project. The libraries were constructed in the EcoRI and HindIII sites of the vector CopyControl pCC1BAC. The EcoRI library comprised 53,000 positive clones, and approximately 99.94% of the clones contained grass carp nuclear DNA inserts (average size, 139.7 kb) covering 7.4x haploid genome equivalents and 2% empty clones. Similarly, the HindIII library comprised 52,216 clones with approximately 99.82% probability of finding any genomic fragments containing single-copy genes; the average insert size was 121.5 kb with 2.8% insert-empty clones, thus providing genome coverage of 6.3x haploid genome equivalents of grass carp. We selected gene-specific probes for screening the target gene clones in the HindIII library. In all, we obtained 31 positive clones, which were identified for every gene, with an average of 6.2 BAC clones per gene probe. Thus, we succeeded in constructing the desired BAC libraries, which should provide an important foundation for future physical mapping and whole-genome sequencing in grass carp

    Behavior and Impact of Zirconium in the Soil–Plant System: Plant Uptake and Phytotoxicity

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    Because of the large number of sites they pollute, toxic metals that contaminate terrestrial ecosystems are increasingly of environmental and sanitary concern (Uzu et al. 2010, 2011; Shahid et al. 2011a, b, 2012a). Among such metals is zirconium (Zr), which has the atomic number 40 and is a transition metal that resembles titanium in physical and chemical properties (Zaccone et al. 2008). Zr is widely used in many chemical industry processes and in nuclear reactors (Sandoval et al. 2011; Kamal et al. 2011), owing to its useful properties like hardness, corrosion-resistance and permeable to neutrons (Mushtaq 2012). Hence, the recent increased use of Zr by industry, and the occurrence of the Chernobyl and Fukashima catastrophe have enhanced environmental levels in soil and waters (Yirchenko and Agapkina 1993; Mosulishvili et al. 1994 ; Kruglov et al. 1996)

    Immunohistochemical and transcriptional expression of Matrix Metalloproteinases in full-term human umbilical cord and Human Umbilical Vein Endothelial Cells

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    Matrix metalloproteinases (MMPs) are extracellular zinc-dependent endopeptidases involved in the degradation and remodelling of extracellular matrix in physiological and pathological processes. MMPs also have a role on cell proliferation, migration, differentiation, angiogenesis and apoptosis. Umbilical cord is a special organ subjected to many changes during pre-natal life and whose cells can maintain a certain degree of plasticity also in post-natal period; for example recently they have been used as a source of stem cells. In this work we investigated the expression of MMPs in human umbilical cord and Human Umbilical Vein Endothelial Cells (HUVEC) though immunohistochemistry, RT-PCR and gelatin zymography. MMP-2 protein is expressed in the amniotic epithelium of human umbilical cord and in few sub-epithelial fibroblasts, while MMP-3 and MMP-10 only in the umbilical epithelium. MMP-8, MMP-9 and MMP-13 immunoreactivity is localised in the epithelium and in Wharton\u2019s jelly mesenchymal cells. Immunocytochemistry also revealed protein expression for MMP-2, 3, 8, 9 and 10 in cultured HUVEC. In agreement with immunohistochemical data, RT-PCR analysis performed on samples of whole umbilical cord confirmed the transcriptional expression for the genes encoding all the six matrix metalloproteinases investigated, while in HUVEC only the expression of MMP-2, 3, 9, 10 and 13 mRNAs was detected. Gelatin zymograpgy showed a clear MMP-2 and MMP-9 enzymatic activity in the conditioned medium of HUVEC at different culture passages, suggesting that HUVEC secrete gelatinases, that afterwards undergo extracellular activation, and this ability is not affected by passage number

    Anti-tumor effect of Liqi, a traditional Chinese medicine prescription, in tumor bearing mice

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    <p>Abstract</p> <p>Background</p> <p><it>Liqi</it>, an herbal preparation used in traditional Chinese medicine, has been used to treat cancer in China for centuries. We investigated the anti-tumor effects of liqi and their mechanisms in mice that had been xenografted with tumors.</p> <p>Methods</p> <p>Sarcoma 180 tumor, Lewis lung carcinoma, and SGC-7901 cells were implanted in BALB/c mice, C57BL/6 mice, and BALB/c nude mice, respectively. Liqi was administered to subgroups of these mice. The tumor weight and size were measured. Cell cycle analysis and T lymphocyte subsets were determined by flow cytometry. The activity of NK cells and TNF was tested using cytotoxicity assay on YAC-1 cells and L929 cells, respectively, and the activity of IL-2 was tested with an IL-2-dependent CTLL-2 cell proliferation assay. Platelet aggregation was monitored by measuring electric impedance, and the levels of thromboxane A2 (TXA<sub>2</sub>) and prostacyclin (PGI<sub>2</sub>) in blood were measured by <sup>125</sup>I-TXB<sub>2 </sub>and <sup>125</sup>I-Keto-PGF<sub>1α </sub>radioimmunoassay.</p> <p>Results</p> <p>The results showed that liqi inhibited tumor growth in tumor-implanted mice and arrested the cell proliferation in the G0/G1 phase and reduced the portion of cells in S and G2/M phase for SGC-7901 cells. Liqi increased the activity of NK cells and TNF-α, stimulated IL-2 production and activity, and regulated T lymphocyte subpopulations. Liqi inhibited the Lewis lung carcinoma metastasis by inhibiting platelet aggregation and normalizing the balance between TXA<sub>2 </sub>and PGI<sub>2</sub>.</p> <p>Conclusion</p> <p>All these findings demonstrated that liqi has an anti-tumor effect in vivo. The mechanism may be related to immune regulation and anticoagulation effects.</p
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