169,960 research outputs found
The coalescence of supported gold nanoparticles induced by nanosecond laser irradiation
No full textGold nanoparticles supported on a quartz substrate are fabricated by e-beam lithography and subjected to nanosecond laser irradiation to induce coalescence. In combination with ex-situ scanning electron microscopy and optical extinction spectra, transmission is monitored in-situ to determine the characteristic coalescence time, the threshold fluence for the onset of coalescence and the produced particle morphology. Parallel molecular dynamics simulation is employed and shown to reasonably predict the coalescence time, thus explaining the experimental results
Nanomaterial enabled laser transfer of temperature sensitive organic light emitting diode materials
No full textDamage-free low temperature pulsed laser printing of gold nanoinks on polymers
No full textIn this study, pulsed laser based curing of a printed nanoink (nanoparticle ink) combined with moderate and controlled substrate heating was investigated to create microconductors at low enough temperatures appropriate for polymeric substrates. The present work relies on (1) the melting temperature depression of nanoparticles smaller than a critical size, (2) DOD (drop on demand) jettability of nanoparticle ink, and (3) control of the heat affected zone induced by pulsed laser heating. In the experiments, gold nanoparticles of 3-7 nm diameter dissolved in toluene solvent were used as ink. This nanoink was printed on a polymeric substrate that was heated to evaporate the solvent during or after printing. The overall morphology of the gold microline was determined by the printing process and controlled by changing the substrate temperature during jetting. In addition, the printed line width of about 140 mu m at the room temperature decreased to 70-80 mu m when the substrate is heated at 90 degrees C. By employing a microsecond pulsed laser, the nanoparticles were melted and coalesced at low temperature to form a conductive microline which had just 3-4 times higher resistivity than the bulk value without damaging the temperature sensitive polymeric substrate. This gold film also survived after Scotch tape test. These are remarkable results, considering the fact that the melting temperature of bulk gold is 1064 degrees C and the polymeric substrate can be thermally damaged at temperatures as low as 500 degrees C.N
Design and Testing of Bistable Lattices with Tensegrity Architecture and Nanoscale Features Fabricated by Multiphoton Lithography
No full textA bistable response is an innate feature of tensegrity metamaterials, which is a conundrum to attain in other metamaterials, since it ushers unconventional static and dynamical mechanical behaviors. This paper investigates the design, modeling, fabrication and testing of bistable lattices with tensegrity architecture and nanoscale features. First, a method to design bistable lattices tessellating tensegrity units is formulated. The additive manufacturing of these structures is performed through multiphoton lithography, which enables the fabrication of microscale structures with nanoscale features and extremely high resolution. Different modular lattices, comprised of struts with 250 nm minimum radius, are tested under loading-unloading uniaxial compression nanoindentation tests. The compression tests confirmed the activation of the designed bistable twisting mechanism in the examined lattices, combined with a moderate viscoelastic response. The force-displacement plots of the 3D assemblies of bistable tensegrity prisms reveal a softening behavior during the loading from the primary stable configuration and a subsequent snapping event that drives the structure into a secondary stable configuration. The twisting mechanism that characterizes such a transition is preserved after unloading and during repeated loading-unloading cycles. The results of the present study elucidate that fabrication of multistable tensegrity lattices is highly feasible via multiphoton lithography and promulgates the fabrication of multi-cell tensegrity metamaterials with unprecedented static and dynamic responses
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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