44 research outputs found

    Minimal residual disease in breast cancer: an overview of circulating and disseminated tumour cells

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    Free volume and interstitial mesopores in silica filled poly(I-trimethylsilyl-l-propyne) nanocomposites

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    The free volume sizes and interstitial mesopore sizes in poly(l-trimethylsilyl-l-propyne) (PTMSP)/silica nanocomposites and the correlation between nitrogen permeability and cavity sizes were studied with positron annihilation lifetime spectroscopy (PALS) at filler concentrations between 0 and 50 wt %. A bimodal free volume distribution was observed for PTMSP, and the size of the larger free volume cavities was significantly increased upon addition of hydrophobic fumed silica. Nanometer-sized interstitial cavities in filler agglomerates were observed in all PTMSP/fumed silica nanocomposites and in neat hydrophobic fumed silica. The radius of these interstitial mesopores in the nanocomposites decreased with decreasing filler concentration. A strong correlation between nitrogen permeability and the volume of the interstitial mesopores in the nanocomposite membranes was observed
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