Publications (7)5.73 Total impact
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Dataset: Supplementary Video 3 High-speed recording of ejecting spores
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Dataset: Supplementary Video 4 High-speed recording of ejecting spores
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Dataset: Supplementary Video 2 Real-time recording of isolated spores
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Dataset: Supplementary Video 1 - Real-time recording of single sporangium
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Article: The role of tap duration for the steady state density of vibrated granular media
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ABSTRACT: We revisit the problem of compaction of a column of granular matter exposed to discrete taps. We accurately control the vertical motion of the column, which allows us to vary the duration T and the amplitude A of single-cycle sinusoidal taps independently. We find that the density of the material at the reversible branch depends both on A and T. By comparing the densities on the reversible branches obtained for a range of values of T, we find that we can collapse all data when plotted as function of A/T, which scales similar to both the liftoff velocity and the time of flight of the packing. We further show that switching between states obtained for different A and T, but chosen such that their densities on the reversible branches match, does not lead to appreciable hysteresis. We conclude that the appropriate control parameter for sinusoidal tapping is not the peak acceleration \Gamma \sim A/T^2, as is usually assumed, but rather \Gamma T \sim A/T. Comment: 6 pages, 7 figures. Final version03/2009; -
Article: Spore movement driven by the spore wall in an eusporangiate fern
Grana. 01/2009; 48(2):122-127. -
Article: Improved piercing of microneedle arrays in dermatomed human skin by an impact insertion method.
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ABSTRACT: An electrical applicator was designed, which can pierce short microneedles into the skin with a predefined velocity. Three different shapes of microneedles were used, namely 300 mum assembled hollow metal microneedle arrays, 300 mum solid metal microneedle arrays and 245 mum hollow silicon microneedle arrays. The latter are available as 4x4, 6x6 and 9x9 arrays. When using a velocity of 1 or 3 m/s reproducible piercing of dermatomed and full thickness human skin was evident from the appearance of blue spots on the dermal side of the skin after Trypan Blue treatment and the presence of fluorescently labeled particles in dermatomed skin. Manual piercing did not result in the appearance of blue spots. Transport studies revealed that i) piercing of microneedles with a predefined velocity into human skin resulted in a drastic enhancement of the Cascade Blue (CB, Mw 538) transport, ii) A higher piercing velocity resulted in a higher CB transport rate, iii) The CB transport rate was also dependent on the shape of the microneedles and iv) no difference in transport rate was observed between 4x4, 6x6 and 9x9 hollow silicon microneedle arrays.Journal of Controlled Release 06/2008; 128(1):80-8. · 5.73 Impact Factor