10 research outputs found

    Energy coverage in wireless powered sub-6 GHz and millimeter wave dense cellular networks

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    This paper focuses on the energy coverage in wireless powered sub-6 GHz and millimeter wave (mmWave) dense cellular networks, where mobile devices harvest RF energy from sub-6 GHz or mmWave base stations (BSS). The expressions for energy coverage probability in sub-6 GHz and mmWave tiers are respectively derived. The comparisons between sub-6 GHz and mmWave RF energy harvesting are analyzed. In particular, we provide the sufficient conditions for the case that wireless energy harvesting in mmWave tier is better than that in sub-6 GHz tier. Furthermore, in hybrid cellular networks with mode selection mechanism, the probability that a mobile device selects a sub-6 GHz BS or mmWave BS for wireless power transfer is also theoretically obtained

    Visualization 4: Camera array based light field microscopy

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    The applications of light field video of drosophila larva to 3D DPC and phase reconstruction. Originally published in Biomedical Optics Express on 01 September 2015 (boe-6-9-3179

    Visualization 5: Camera array based light field microscopy

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    The light field and synthetic refocusing videos of the Caenorhabditis elegans (C. elegans) in the water. Originally published in Biomedical Optics Express on 01 September 2015 (boe-6-9-3179

    Visualization 1: Camera array based light field microscopy

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    The proposed camera array based light field microscopy (CALM) prototype system. Originally published in Biomedical Optics Express on 01 September 2015 (boe-6-9-3179

    Hybrid TiO<sub>2</sub>–SnO<sub>2</sub> Nanotube Arrays for Dye-Sensitized Solar Cells

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    Tin oxide (SnO<sub>2</sub>) is a promising wide band gap semiconductor material for dye-sensitized solar cells (DSCs) because of its high bulk electron mobility. Employing vertically ordered 1-D nanostructures of SnO<sub>2</sub> as the photoanode may overcome the limit of current DSCs by using new redox mediators with faster kinetics than currently used ones. Synthesizing such nanostructures and integrating them into DSCs, however, has been proven challenging. Here, we demonstrate that, by using ZnO nanowires as a sacrificial template, vertically aligned SnO<sub>2</sub> nanotube arrays may be feasibly synthesized through a liquid-phase conversion process, and the synthesized SnO<sub>2</sub> nanotubes can be further coated with a thin layer of TiO<sub>2</sub> to form hybrid TiO<sub>2</sub>–SnO<sub>2</sub> nanotube arrays. Both the resulting SnO<sub>2</sub> and hybrid TiO<sub>2</sub>–SnO<sub>2</sub> nanotube arrays are used to fabricate DSCs, and the best performing cell delivers a promising efficiency of 3.53%. Transient photovoltage measurements indicate that the electron recombination lifetime in hybrid TiO<sub>2</sub>–SnO<sub>2</sub> nanotubes is significantly larger than those in TiO<sub>2</sub> nanotubes, ZnO nanowires, and films of sintered TiO<sub>2</sub> nanoparticles, suggesting promise of the TiO<sub>2</sub>-coated SnO<sub>2</sub> nanotubes for further improvement of DSCs

    High-Efficiency Solid-State Dye-Sensitized Solar Cells Based on TiO<sub>2</sub>-Coated ZnO Nanowire Arrays

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    Replacing the liquid electrolytes in dye-sensitized solar cells (DSCs) with solid-state hole-transporting materials (HTMs) may solve the packaging challenge and improve the long-term stability of DSCs. The efficiencies of such solid-state DSCs (ss-DSCs), however, have been far below the efficiencies of their counterparts that use liquid electrolytes, primarily due to the challenges in filling HTMs into thick enough sensitized films based on sintered TiO<sub>2</sub> nanoparticles. Here we report fabrication of high-efficiency ss-DSCs using multilayer TiO<sub>2</sub>-coated ZnO nanowire arrays as the photoanodes. The straight channel between the vertically aligned nanostructures combined with a newly developed multistep HTM filling process allows us to effectively fill sensitized films as thick as 50 μm with the HTMs. The resulting ss-DSCs yield an average power conversion efficiency of 5.65%

    Sorting Short Fragments of Single-Stranded DNA with an Evolving Electric Double Layer

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    We demonstrate a new procedure for separation of single-stranded DNA (ssDNA) fragments that are anchored to the surface of a gold electrode by end hybridization. The new separation procedure takes advantage of the strong yet evolving nonuniform electric field near the gold surface in contact with a buffer solution gradually being diluted with deionized water. Separation of short ssDNA fragments is demonstrated by monitoring the DNA at the gold surface with <i>in situ</i> fluorescence measurement. The experimental results can be rationalized with a simple theoretical model of electric double layer that relates the strength of the surface pulling force to the ionic concentration of the changing buffer solution

    Media 1: Coded aperture pair for quantitative phase imaging

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    Originally published in Optics Letters on 01 October 2014 (ol-39-19-5776

    Media 2: Coded aperture pair for quantitative phase imaging

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    Originally published in Optics Letters on 01 October 2014 (ol-39-19-5776

    A Glutamine-Rich Carrier Efficiently Delivers Anti-CD47 siRNA Driven by a “Glutamine Trap” To Inhibit Lung Cancer Cell Growth

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    It is not efficient enough using the current approaches for tumor-selective drug delivery based on the EPR effect and ligand–receptor interactions, and they have largely failed to translate into the clinic. Therefore, it is urgent to explore an enhanced strategy for effective delivery of anticancer agents. Clinically, many cancers require large amounts of glutamine for their continued growth and survival, resulting in circulating glutamine extraction by the tumor being much greater than that for any organs, behaving as a “glutamine trap”. In the present study, we sought to elucidate whether the glutamine-trap effect could be exploited to deliver therapeutic agents to selectively kill cancer cells. Here, a macromolecular glutamine analogue, glutamine-functionalized branched polyethylenimine (GPI), was constructed as the carrier to deliver anti-CD47 siRNA for the blockage of CD47 “don’t eat me” signals on cancer cells. The GPI/siRNA glutamine-rich polyplexes exhibited remarkably high levels of cellular uptake by glutamine-dependent lung cancer cells, wild-type A549 cells (A549<sup>WT</sup>), and its cisplatin-resistant cells (A549<sup>DDP</sup>), specifically under glutamine-depleted conditions. It was noted that the glutamine transporter ASCT2 was highly expressed both on A549<sup>WT</sup> and A549<sup>DDP</sup> but with almost no expression in normal human lung fibroblasts cells. Inhibition of ASCT2 significantly prevented the internalization of GPI polyplexes. These findings raised the intriguing possibility that the glutamine-rich GPI polyplexes utilize the ASCT2 pathway to selectively facilitate their cellular uptake by cancer cells. GPI further delivered anti-CD47 siRNA efficiently both in vitro and in vivo to downregulate the intratumoral mRNA and protein expression levels of CD47. CD47 functions as a “don’t eat me” signal and binds to the immunoreceptor SIRPα inducing evasion of phagocytic clearance. GPI/anti-CD47 siRNA polyplexes achieved significant antitumor activities both on A549<sup>WT</sup> and A549<sup>DDP</sup> tumor-bearing nude mice. Notably, it had no adverse effect on CD47-expressing red blood cells and platelets, likely because of selective delivery. Therefore, the glutamine-rich carrier GPI driven by the glutamine-trap effect provides a promising new strategy for designing anticancer drug delivery systems
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