Browsing by Department "Nanyang Technological University"

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Bioinspired Functionally Graded Composite Assembled Using Cellulose Nanocrystals and Genetically Engineered Proteins with Controlled Biomineralization
(2021-10-21) Mohammadi, Pezhman; Gandier, Julie-Anne; Nonappa; Wagermaier, Wolfgang; Miserez, Ali; Penttilä, Merja
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Nature provides unique insights into design strategies evolved by living organisms to construct robust materials with a combination of mechanical properties that are challenging to replicate synthetically. Hereby, inspired by the impact-resistant dactyl club of the stomatopod, a mineralized biocomposite is rationally designed and produced in the complex shapes of dental implant crowns exhibiting high strength, stiffness, and fracture toughness. This material consists of an expanded helicoidal organization of cellulose nanocrystals (CNCs) mixed with genetically engineered proteins that regulate both binding to CNCs and in situ growth of reinforcing apatite crystals. Critically, the structural properties emerge from controlled self-assembly across multiple length scales regulated by rational engineering and phase separation of the protein components. This work replicates multiscale biomanufacturing of a model biological material and also offers an innovative platform to synthesize multifunctional biocomposites whose properties can be finely regulated by colloidal self-assembly and engineering of its constitutive protein building blocks.
Energy Loss for Droplets Bouncing Off Superhydrophobic Surfaces
(2023-02-28) Thenarianto, Calvin; Koh, Xue Qi; Lin, Marcus; Jokinen, Ville; Daniel, Dan
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
A water droplet can bounce off superhydrophobic surfaces multiple times before coming to a stop. The energy loss for such droplet rebounds can be quantified by the ratio of the rebound speed UR and the initial impact speed UI; i.e., its restitution coefficient e = UR/UI. Despite much work in this area, a mechanistic explanation for the energy loss for rebounding droplets is still lacking. Here, we measured e for submillimeter-and millimeter-sized droplets impacting two different superhydrophobic surfaces over a wide range of UI (4- 700 cm s-1). We proposed simple scaling laws to explain the observed nonmonotonic dependence of e on UI. In the limit of low UI, energy loss is dominated by contact-line pinning and e is sensitive to the surface wetting properties, in particular to contact angle hysteresis Delta cos 0 of the surface. In contrast, e is dominated by inertial-capillary effects and does not depend on Delta cos 0 in the limit of high UI.
Fast-Decodable Space-Time Codes for the N-Relay and Multiple-Access MIMO Channel
(2016-03-01) Barreal, Amaro; Hollanti, Camilla; Markin, Nadya
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
In this article, the first general constructions of fast-decodable, more specifically (conditionally) g-group decodable, space-time block codes for the nonorthogonal amplify and forward (NAF) multiple-input multiple-output (MIMO) relay channel under the half-duplex constraint are proposed. In this scenario, the source and the intermediate relays used for data amplification are allowed to employ multiple antennas for data transmission and reception. The worst-case decoding complexity of the obtained codes is reduced by up to 75%. In addition to being fast-decodable, the proposed codes achieve full-diversity and have nonvanishing determinants, which has been shown to be useful for achieving the optimal diversity-multiplexing tradeoff (DMT) of the NAF channel. Furthermore, it is shown that the same techniques as in the cooperative scenario can be utilized to achieve fast-decodability for K-user MIMO multiple-access channel (MAC) space-time block codes. The resulting codes in addition exhibit the conditional nonvanishing determinant property which, for its part, has been shown to be useful for achieving the optimal MAC-DMT.