Minimal energy control of a nanoelectromechanical memory element

The Pontryagin minimal energy control approach has been applied to minimise the switching energy in a nanoelectromechanical memory system and to characterise global stability of the oscillatory states of the bistable memory element. A comparison of two previously experimentally determined pulse-type control signals with Pontryagin control function has been performed, and the superiority of the Pontryagin approach with regard to power consumption has been demonstrated. An analysis of global stability shows how values of minimal energy can be utilized in order to specify equally stable states

Biomimetic surfaces exhibiting extreme wettability properties for tissue engineering applications

Surfaces exhibiting hierarchical topographic organization, from the nano to the micro scale, may present extreme wettability properties, ranging from (lotus-like) superhydrophobic to superhydrophilic behaviour. Such surfaces may be used as innovative substrates to infer cell behaviour and protein adsorption onto surfaces beyond the conventional hydrophobic-to-hydrophilic character.  We proposed a rapid procedure to produce superhydrophobic substrates in polymeric films that could change the wettability up to contact angles near zero through further modification using plasma or UV/ozone radiation. By spatially control the regions of surface modification it is possible to produce surfaces with gradients in wettability or pattern wettable areas surrounded by superhydrophobic spaces. We have been suggesting the use of such devices for ex-vivo biomedical applications, such as platforms for combinatory analysis of 2D or 3D biomaterials and cells, including miniaturised hydrogels and scaffolds with multiple combinations of compositions and properties, and also to produce open microfluidic devices.  The developed superhydrophobic substrates may be also used to process polymeric particles in mild conditions and with unique structural characteristics, specially designed for tissue engineering applications.</p

Designing biomaterials for tissue engineering based on the deconstruction of the native cellular environment

Strategies in Tissue Engineering and Regenerative Medicine are often based on the use of biomaterials able to support and control cellular activity. Two aspects should be considered in the development of high performance bioinstructive biomaterials. (i) The inherent complexity associated with the multiple possibilities in the biomaterials/cells selection, usually addressed using high-throughput combinatorial tests; and (ii) the unpredictability of the biological outcome of a particular solution. The last facet requires a rational decomposition of the main spatial and temporal cues at the cellular level that drive new-tissue formation upon injury, to be then transposed into adequate biomaterialsâ design. Several nano/micro-technologies may be used to process biomaterials with different shapes and sizes, permitting to engineer biomimetic and hierarchical biomedical devices. As a particular case study, the layer-by-layer assembly method is suggested as a versatile and robust framework to formulate multifunctional and tunable polymer-based biomaterials able to address this exercise of deconstruction and reconstruction.The author is grateful for the Portuguese Foundation for Science and Technology (FCT) financial support in the scope of project PTDC/CTM-BIO/1814/2012. The author acknowledges Dr. Iva Pashkuleva for the critical review of the manuscript and Dr. Luca Gasperini for preparation of several schemes

Magnetic force-based tissue engineering and regenerative medicine

Among other biomedical applications, magnetic nanoparticles and liposomes have a vast field of applications in tissue engineering and regenerative medicine. Magnetic nanoparticles and liposomes, when introduced into cells to be cultured, maneuver the cell's positioning by the appropriate use of magnets to create more complex tissue structures than those that are achieved by conventional culture methods.This work was supported by the Portuguese Foundation for Science and Technology (FCT) and the Andalusian Initiative for Advanced Therapies (Ministry of Health of the Andalusian Regional Government). Special thanks to Dr. Vega Asensio (www.NorArte.es) and her beautiful scientific illustrations for the review. Emilio Castro thanks his postdoctoral fellowship from Health and Progress Foundation (Mobility Program for Nanomedicine)

Mixtures of Bose gases confined in concentrically coupled annular traps

A two-component Bose-Einstein condensate confined in an axially-symmetric potential with two local minima, resembling two concentric annular traps, is investigated. The system shows a number of quantum phase transitions that result from the competition between phase coexistence, and radial/azimuthal phase separation. The ground-state phase diagram, as well as the rotational properties, including the (meta)stability of currents in this system, are analysed.Comment: 6 pages, 5 figures, minor revision

A study on usability criteria regarding interfaces for children

Comunicação apresentada no Interact 2005 Workshop - "Child computer interaction : methodological reasearch", Rome, Italy, 13 Setembro 2005.Building an application's interface is always an attempt to match the software functions with the users' mental model. This task is complicated enough when an adult is designing the interface to other adults. When the users are children, the challenge is harder still. How can the users' mental model be predicted? This communication deals with a study that aims to answer this question, going from the characteristics of the children cognitive thought to the discovery of efficient design guidelines for interfaces

A study about usability criteria on computer interfaces for children

This study's main goal is to produce a set of guidelines intended to aid a programmer who wishes to build a computer application targeted at children ranging from 5 to 7 years old