233 research outputs found
Analytic results for the three-sphere swimmer at low Reynolds number
The simple model of a low Reynolds number swimmer made from three spheres
that are connected by two arms is considered in its general form and analyzed.
The swimming velocity, force--velocity response, power consumption, and
efficiency of the swimmer are calculated both for general deformations and also
for specific model prescriptions. The role of noise and coherence in the stroke
cycle is also discussed.Comment: 7 pages, 3 figure
43. RĂ©sultats prĂ©liminaires dâune tomothĂ©rapie hĂ©licoĂŻdale adjuvante avec boost intĂ©grĂ© dans le cadre dâun traitement conservateur dâun cancer du sein
Controlled rotary motion of light-driven molecular motors assembled on a gold film
Using circular dichroism (CD) spectroscopy, we show that light-driven rotary molecular motors based on overcrowded alkenes can function in a self-assembled monolayer on semi-transparent gold films.
Glancing angle metal evaporation synthesis of catalytic swimming Janus colloids with well defined angular velocity
The ability to control the degree of spin, or rotational velocity, for catalytic swimming devices opens up the potential to access well defined spiralling trajectories, enhance cargo binding rate, and realise theoretically proposed behaviour such as chiral diffusion. Here we assess the potential to impart a well-defined spin to individual catalytic Janus swimmers by using glancing angle metal evaporation onto a colloidal crystal to break the symmetry of the catalytic patch due to shadowing by neighbouring colloids. Using this approach we demonstrate a well-defined relationship between the glancing angle and the ratio of rotational to translational velocity. This allows batches of colloids with well-defined spin rates in the range 0.25 to 2.5 Hz to be produced. With reference to the shape and thickness variations across the catalytically active shapes, and their propulsion mechanism we discuss the factors that can lead to the observed variations in rotational propulsion
Stimuliâresponsive microjets with reconfigurable shape
Flexible thermoresponsive polymeric microjets are formed by the selfâfolding of polymeric layers containing a thin Pt film used as catalyst for selfâpropulsion in solutions containing hydrogen peroxide. The flexible microjets can reversibly fold and unfold in an accurate manner by applying changes in temperature to the solution in which they are immersed. This effect allows microjets to rapidly start and stop multiple times by controlling the radius of curvature of the microjet. This work opens many possibilities in the field of artificial nanodevices, for fundamental studies on selfâpropulsion at the microscale, and also for biorelated applications
Supermultiplexed optical imaging and barcoding with engineered polyynes
Optical multiplexing has a large impact in photonics, the life sciences and biomedicine. However, current technology is limited by a 'multiplexing ceiling' from existing optical materials. Here we engineered a class of polyyne-based materials for optical supermultiplexing. We achieved 20 distinct Raman frequencies, as 'Carbon rainbow', through rational engineering of conjugation length, bond-selective isotope doping and end-capping substitution of polyynes. With further probe functionalization, we demonstrated ten-color organelle imaging in individual living cells with high specificity, sensitivity and photostability. Moreover, we realized optical data storage and identification by combinatorial barcoding, yielding to our knowledge the largest number of distinct spectral barcodes to date. Therefore, these polyynes hold great promise in live-cell imaging and sorting as well as in high-throughput diagnostics and screening
Nanoparticle vesicle encoding for imaging and tracking cell populations.
For phenotypic behavior to be understood in the context of cell lineage and local environment, properties of individual cells must be measured relative to population-wide traits. However, the inability to accurately identify, track and measure thousands of single cells via high-throughput microscopy has impeded dynamic studies of cell populations. We demonstrate unique labeling of cells, driven by the heterogeneous random uptake of fluorescent nanoparticles of different emission colors. By sequentially exposing a cell population to different particles, we generated a large number of unique digital codes, which corresponded to the cell-specific number of nanoparticle-loaded vesicles and were visible within a given fluorescence channel. When three colors are used, the assay can self-generate over 17,000 individual codes identifiable using a typical fluorescence microscope. The color-codes provided immediate visualization of cell identity and allowed us to track human cells with a success rate of 78% across image frames separated by 8 h
Tubular microjets: Fabrication, factors affecting the motion and mechanism of propulsion
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