1,009 research outputs found
Fractoluminescence characterization of the energy dissipated during fast fracture of glass
Fractoluminescence experiments are performed on two kinds of silicate
glasses. All the light spectra collected during dynamic fracture reveal a black
body radiator behaviour, which is interpreted as a crack velocity-dependent
temperature rise close to the crack tip. Crack velocities are estimated to be
of the order of 1300 m.s and fracture process zones are shown to extend
over a few nanometers.Comment: Accepted for publication in Europhysics Letters; 5 pages; 4 figure
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Selective Lanthanide Sensing with Gold Nanoparticles and Hydroxypyridinone Chelators.
The octadentate hydroxypyridinone chelator 3,4,3-LI(1,2-HOPO) is a promising therapeutic agent because of its high affinity for f-block elements and noncytotoxicity at medical dosages. The interaction between 3,4,3-LI(1,2-HOPO) and other biomedically relevant metals such as gold, however, has not been explored. Gold nanoparticles functionalized with chelators have demonstrated great potential in theranostics, yet thus far, no protocol that combines 3,4,3-LI(1,2-HOPO) and colloidal gold has been developed. Here, we characterize the solution thermodynamic properties of the complexes formed between 3,4,3-LI(1,2-HOPO) and Au3+ ions and demonstrate how under specific pH conditions the chelator promotes the growth of gold nanoparticles, acting as both reducing and stabilizing agent. 3,4,3-LI(1,2-HOPO) ligands on the nanoparticle surface remain active and selective toward f-block elements, as evidenced by gold nanoparticle selective aggregation. Finally, a new colorimetric assay capable of reaching the detection levels necessary for the quantification of lanthanides in waste from industrial processes is developed based on the inhibition of particle growth by lanthanides
Thinking deep. Acting on top. Underground built heritage and its fringe as a community catalyst for local sustainable development : Exploratory cases from poland and greece
Underground Built Heritage (UBH) is a distinct class of cultural heritage providing a focal point for community pride and engagement to become a springboard for local sustainable development (LSD). This research aims to articulate how local UBH and its fringe serve as a facilitator of communal identity to mobilize community care towards social and economic development with less involvement from the state and the market actors. For this purpose, local (and less-conspicuous) cases of UBH are employed in Warsaw, Poland, and Volos, Greece, indicating the power of UBH to connect and engage local communities with places, triggering a momentum for a truly bottom-up action that pays less attention to market considerations and state support. The studied UBH sites have been discussed according to an established common framework, dealing with five main issues: (a) general context and status, (b) history, (c) users and management, (d) ecosystem services, and (e) introduction of the paradigm of living labs. The analysis was based on a thorough literature review and complemented by field observations and interviews. The results provide evidence for UBH as a potential facilitator of social and economic development. The case studies in Poland and Greece showed that local actors were involved in activities and social networks of tacit knowledge, generating community building to reinforce bottom-up activities in contact with UBH
Turbulent dispersion of particles in a differentially heated vertical channel
Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.Direct numerical simulations of particle dispersion in the
turbulent natural convection flow between two vertical walls
kept at constant but different temperatures are reported. It is
assumed that the particles do not affect the flow (i.e. the dilute
phase approximation is adopted). Particles with different levels
of inertia or Stokes numbers (0.843≤St≤17.45) are tracked
according to the drag force imposed by the fluid. The gravity
force is also included for two cases, St=0.843 and St=17.45.
The different level of turbulence near the wall and near the
center of the channel produces, as in isothermal turbulent
channel or pipe flow, a larger concentration of particles near the
wall. This effect becomes more important, and the deposition
velocity of particles on the wall increases, as the particle inertia
is increased in a certain range of Stokes numbers
(0.843≤St≤8.38). The simulations at St=8.38 and St=17.45
predict similar concentration profiles and deposition velocities
according to the large inertia of these particles. For the
conditions considered, the gravity vector imposes a strong
descending motion on particles and this produces the increase
of the particle concentration near the wall in comparison with
the results without the gravity force.pm201
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