Development of polymeric anepectic meshes: Auxetic metamaterials with negative thermal expansion

This paper reports the application of additive manufacturing technology to fabricate bi-dimensional lightweight composite meshes capable of demonstrating auxetic properties (negative Poisson's ratio (NPR)) in combination with negative thermal expansion (NTE) behaviour, using as constituent materials polymers that do not exhibit NTE behaviour. To describe the combination of NPR and NTE characteristics, the designation of 'anepectic' is being proposed. Each mesh, obtained from varying either the material combination or the design parameters, was tested on a heated silicone bath to study the effects of the different combinations on the coefficient of thermal expansion (CTE). It was found that all meshes studied demonstrated a successful combination of NPR and NTE behaviours, and it was revealed that there is a possibility to tailor the meshes to activate the NTE behaviour within a chosen range of temperatures. For an extreme case, a Poisson's ratio of-0.056, along with a CTE of-1568 × 10 -6 K -1 has been achieved.authorsversionpublishe

Emergent heterogeneity in putative mesenchymal stem cell colonies: Single-cell time lapsed analysis

Grant No. 1122374Bone marrow stromal cells (BMSCs) include a subset of stem cells that are considered promising for developmental studies and therapeutic applications. While it is appreciated generally that BMSC populations can exhibit morphological and functional heterogeneity upon in vitro culture expansion, the potential for heterogeneity within a single colony forming unit–generated ostensibly from a single mother cell–is less explored but is critical to design of both fundamental studies and cell therapy production. Here we observed BMSC colony formation in real time via time lapsed optical imaging and analysis, to quantify whether and how heterogeneity emerged over multiple cell divisions spanning the duration of a typical colony formation unit assay. These analyses demonstrate that such colonies are neither homogeneous subpopulations of stem cells nor necessarily derived from single originating cells. While the mechanisms for and causes of this intracolony heterogeneity are not understood fully, we further demonstrate that extensive cell-cell contacts do not correlate with senescence, but that media exchange was concurrent with diversification in even the most uniform single-cell-derived colonies. These direct quantitative observations and visualizations of colony formation provide new insights that are motivated by significant implications for both basic research and stem cell-based therapies.publishersversionpublishe

A serious game-based solution to prevent bullying

This paper presents a Serious Game with the main purpose of inducing attitude changes as a way to prevent bullying, in a target audience of young people between 10 and 12 years old. The rationale for prevention is: first, to help victims of these aggressive episodes to acquire or improve competencies in avoiding or dealing with future real bullying situations; and, second, to promote empathy towards the victims in bystanders. A back office application complements the game, providing substantial assistance to psychologists while using the game with patients in therapy or in research work. Both components, the game and the back office, were evaluated with volunteers. The user study lead us to the conclusion that the current version of the game holds good potential in bullying prevention: the young people that played the game in a continuous time span, at the end of this testing process have expressed improvements in their bullying prevention strategies. The back office application was positively assessed by the psychologists who tested it. The game deals with strong social features, such as number of friends and invitations to social events (e.g. a birthday party), to which young people give much importance. Additionally, it offers a variability of scenarios and consequences of actions, taking into account the user's performance in the game. The main factors that make the presented solution stand out in comparison with other similar bullying prevention solutions are mainly the following: it includes a back office application to assist therapists with data management features; the role of the player in the game can be chosen accordingly to his own profile; it is possible to play even outside a therapy session (e.g. at home) and it is a portable solution.info:eu-repo/semantics/acceptedVersio