24 research outputs found

    White Privilege and Racism

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    NanoSi low loss horizontal slot waveguides coupled to high Q ring resonators (vol 17, pg 20762, 2009)

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    An erratum is presented in order to correct the values of the Q-factor measured. (C) 2009 Optical Society of Americ

    NanoSi low loss horizontal slot waveguides coupled to high Q ring resonators

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    Si-based horizontal slot waveguides coupled to ring resonators have been fabricated and characterised. The central layer of the slot has been filled by Silicon nanocrystals (Si-nc) obtained by deposition of silicon rich silicon oxide and then thermal annealing. A comparison of various deposition and annealing parameters to form the Si-nc is performed. Propagation losses as low as 3 dB/cm and ring resonator quality factor of 30,000 have been achieved at 1550 nm. (C) 2009 Optical Society of Americ

    Photoluminescence of hydrophilic silicon nanocrystals in aqueous solutions

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    Stable aqueous solutions of undecylenic-acid-grafted silicon nanocrystals (Si-nc) were prepared. The time evolution of the photoluminescence properties of these hydrophilic silicon nanocrystals has been followed on different timescales (hours and days). On a short timescale (hours), Si-nc tend to agglomerate while the PL lineshape and intensity are stable. Agglomeration can be reduced by using suitable surfactants. On a long timescale (days), oxidation of Si-nc occurs even in the presence of surfactants. These two observations render Si-nc very useful as a labeling agent for biosensing

    NanoSi low loss horizontal slot waveguides coupled to high Q ring resonators

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    Si-based horizontal slot waveguides coupled to ring resonators have been fabricated and characterised. The central layer of the slot has been filled by Silicon nanocrystals (Si-nc) obtained by deposition of silicon rich silicon oxide and then thermal annealing. A comparison of various deposition and annealing parameters to form the Si-nc is performed. Propagation losses as low as 3 dB/cm and ring resonator quality factor of 30,000 have been achieved at 1550 nm

    Coupled cavities in one-dimensional photonic crystal based on horizontal slot waveguide structure with Si-nc

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    One-dimensional photonic crystal structure is used for a slow tight effect in a coupled resonators optical horizontal slot waveguide with Si-nc. We report on design, simulations and preliminary optical transmission characterization around 1.55 mu m

    High quality coupled ring resonators based on silicon clusters slot waveguide

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    High Q factor ring resonators based on Si clusters sandwich slot-waveguide structure have been fabricated by standard DUV lithography. These devices are considered an important step towards the demonstration of an all optical logic gate

    Orange and blue luminescence emission to track functionalized porous silicon microparticles inside the cells of the human immune system

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    Porous silicon micro-particles (micro-pSi) with size in the range of 1\u201310 mm are obtained by etching of silicon wafers followed by sonication. The derivatization of the micro-pSi surface by wet chemistry (silylation and coupling with a diamine) yields an interface, which exposes negative (carboxylic) or positive (amine) groups at pH 7.4. The surface modification, beyond the introduction of groups for the drug loading by covalent or electrostatic interactions, stabilizes the intense orange luminescence characteristic of the silicon nano-crystallites. Derivatization by amines introduces also a second emission in the blue region, which follows a different excitation pathway and can be attributed to the interface defects. The micro-pSi are efficiently internalized by human dendritic cells and do not show any toxic effect even at a concentration of 1 mg mL1. The intrinsic luminescence of the differently functionalized micro-pSi is preserved inside the cells and permits the selective and efficient tracking of the microparticles without using molecular tags and thus leaving the organic coating available for the interaction with the drug. The results obtained suggest that the functionalized micro-pSi are an efficient platform for simultaneous imaging and delivery of therapeutic agents to the disease site
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