Filters

2017 - 20182

More filters

20232
Reset filters

Settings

End date: 2023 × Start date: 2023 × End date: 2019 × Start date: 2014 × DDC: 600 × Has files: Yes × Publisher: New York, NY [u.a.] : Springer ×

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Morphological Evolution of Pit-Patterned Si(001) Substrates Driven by Surface-Energy Reduction
    (New York, NY [u.a.] : Springer, 2017) Salvalaglio, Marco; Backofen, Rainer; Voigt, Axel; Montalenti, Francesco
    Lateral ordering of heteroepitaxial islands can be conveniently achieved by suitable pit-patterning of the substrate prior to deposition. Controlling shape, orientation, and size of the pits is not trivial as, being metastable, they can significantly evolve during deposition/annealing. In this paper, we exploit a continuum model to explore the typical metastable pit morphologies that can be expected on Si(001), depending on the initial depth/shape. Evolution is predicted using a surface-diffusion model, formulated in a phase-field framework, and tackling surface-energy anisotropy. Results are shown to nicely reproduce typical metastable shapes reported in the literature. Moreover, long time scale evolutions of pit profiles with different depths are found to follow a similar kinetic pathway. The model is also exploited to treat the case of heteroepitaxial growth involving two materials characterized by different facets in their equilibrium Wulff’s shape. This can lead to significant changes in morphologies, such as a rotation of the pit during deposition as evidenced in Ge/Si experiments.
  • Thumbnail Image
    Item
    The Toxic Truth About Carbon Nanotubes in Water Purification: a Perspective View
    (New York, NY [u.a.] : Springer, 2018-6-18) Das, Rasel; Leo, Bey Fen; Murphy, Finbarr
    Without nanosafety guidelines, the long-term sustainability of carbon nanotubes (CNTs) for water purifications is questionable. Current risk measurements of CNTs are overshadowed by uncertainties. New risks associated with CNTs are evolving through different waste water purification routes, and there are knowledge gaps in the risk assessment of CNTs based on their physical properties. Although scientific efforts to design risk estimates are evolving, there remains a paucity of knowledge on the unknown health risks of CNTs. The absence of universal CNT safety guidelines is a specific hindrance. In this paper, we close these gaps and suggested several new risk analysis roots and framework extrapolations from CNT-based water purification technologies. We propose a CNT safety clock that will help assess risk appraisal and management. We suggest that this could form the basis of an acceptable CNT safety guideline. We pay particular emphasis on measuring risks based on CNT physico-chemical properties such as diameter, length, aspect ratio, type, charge, hydrophobicity, functionalities and so on which determine CNT behaviour in waste water treatment plants and subsequent release into the environment.