How to correctly estimate the electric field in capacitively coupled systems for tissue engineering: a comparative study

Capacitively Coupled (CCoupled) electric fields are used to stimulate cell cultures in Tissue Engineering. Knowing the electric field (E-Field) magnitude in the culture medium is fundamental to establish a relationship between stimulus strength and cellular effects. We analysed eight CCoupled studies and sought to corroborate the reported estimates of the E-Field in the culture medium. First, we reviewed the basic physics underlying CCoupled stimulation and delineated three approaches to estimate the E-field. Using these approaches, we found that the reported values were overestimated in five studies, four of which were based on incorrect assumptions. In all studies, insufficient information was provided to reproduce the setup exactly. Creating electrical models of the experimental setup should improve the accuracy of the E-field estimates and enhance reproducibility. For this purpose, we developed a free open-source tool, the E-field Calculator for CCoupled systems, which is available for download from an internet hosting platform.info:eu-repo/semantics/publishedVersio

A review of management tools for OpenSimulator

"Conference on Videogame Sciences and Arts", realizada no Porto de 21-22 de novembro de 2018To host OpenSimulator virtual world servers at educational institutions, system administrators find at their disposal a diversity of web-based management systems with different sets of features. To support the selection among current management tools and provide a baseline from which to identify subsequent development needs, we installed and evaluated 4 of these systems (WiFi pages, OSMW, MWI and jOpenSim), analysing and comparing their features. WiFi pages only provides account-management features. MWI has mostly the same features, but also provides systems administrators with the option of creating their own management website. OSMW has account-management and maintenance features, such as log management and editing of configuration files. jOpenSim provides features for account and event management and feature for generating some actions within virtual world, such as broadcasting a message to all regions. From matching the identified features with the literature-reported requirements for virtual world deployment at educational organizations, we conclude that there is no management tool that fulfils all the functional requirements reported in the literature and, therefore, that the adoption of current tools by system administrators will always requires manually performing some of the administrative tasks. We therefore call for development of novel, more encompassing administrative tools for OpenSimulator virtual worlds.This research has been partially financed by the European Commission [BEACONING H2020ICT-2015-687676]info:eu-repo/semantics/publishedVersio

Multifunctional bacterial cellulose-chitosan tape: an innovative substitute for PVC

Synthetic polymers, generically named plastics, are manufactured from non-renewable sources, such as fossil fuels [1]. In 2020, 367 million metric tons of plastic were produced worldwide, and, only in 2018, global plastic waste volume reached 342.6 million metric tons [2,3]. One of the most used plastics is polyvinyl chloride (PVC), which is not environmentally friendly. The goal of this study was to achieve an eco-friendly substitute for PVC tapes while mimicking their properties and applications. In this way, bacterial cellulose (BC) and chitosan (CH) tapes in different concentrations, 1% and 2%, were developed. Mechanical properties, thickness, bonds between BC and CH and degradation tests were assessed in water and under different temperatures. Mechanical testing showed that the combination of the two polymers resulted in better mechanical performances when compared to BC tape (8.52 ± 1.11 MPa); this may be related to the stronger chemical bonds created between the BC and CH. In addition, BC–CH at 1% revealed closer values of strength compared to PVC tapes (703.19 ± 16.18 MPa and 516.92 ± 22.0 MPa, respectively). Moreover, with the present study we were able to conclude that the incorporation of CH increases tape porosity. Interestingly, higher porosities (BC and CH at 2%) resulted in better mechanical properties upon tensile testing (1344 ± 52.87 MPa). Upon contact with water, the BC–CH mixture at 1% proved to be more resistant and not mechanically affected over time, like PCV tape. Thermally, both tapes with CH revealed to be more resistant than the PVC tape. However, the BC–CH tape at 1% was the most stable over time at all temperatures tested. This preliminary study opens new possibilities to the use of these tapes in sport areas, packaging and pharmaceutical or biomedical fields.This research was funded by the Fundação para a Ciência e a Tecnologia FCT/MCTES (PIDDAC) and Centro2020 through the following Projects: UIDB/04044/2020; UIDP/04044/2020; Associate Laboratory ARISE LA/P/0112/2020; PAMI-ROTEIRO/0328/2013 (Nº 022158).info:eu-repo/semantics/publishedVersio

A multimodal stimulation cell culture bioreactor for tissue engineering: A numerical modelling approach

This research was funded by the Fundação para a Ciência e a Tecnologia (FCT) and Centro2020 through the following Projects: UIDP/04044/2020, PAMI—ROTEIRO/0328/2013 (No 022158) and Stimuli2BioScaffold— Stimuli modelling for BioScaffolds: from numerical modelling to in vitro tests co-financed by COMPETE2020 under the PT2020 programme, and supported by FCT (02/SAICT/2017). Ref. POCI-01-0145-FEDER-032554; Bone2Move—Development of “in vivo” experimental techniques and modeling methodologies for the evaluation of 4D scaffolds on bone defect in sheep model: an integrative research approach co-financed by COMPETE2020 under the PT2020 programme, and supported by FCT (02/SAICT/2017), Project nº 31146; MATIS—MATERIALS AND SUSTAINABLE INDUSTRIAL TECHNOLOGIES (CENTRO-01-0145-FEDER-000014-3362); Instituto de Biofísica e Engenharia Biomédica (IBEB) is supported by Fundação para a Ciência e Tecnologia (FCT), Portugal, under Grant n UIDB/00645/2020. Also supported by UID/BIO/04565/2020.The use of digital twins in tissue engineering (TE) applications is of paramount importance to reduce the number of in vitro and in vivo tests. To pursue this aim, a novel multimodal bioreactor is developed, combining 3D design with numerical stimulation. This approach will facilitate the reproducibility between studies and the platforms optimisation (physical and digital) to enhance TE. The new bioreactor was specifically designed to be additive manufactured, which could not be reproduced with conventional techniques. Specifically, the design suggested allows the application of dual stimulation (electrical and mechanical) of a scaffold cell culture. For the selection of the most appropriate material for bioreactor manufacturing several materials were assessed for their cytotoxicity. Numerical modelling methods were then applied to the new bioreactor using one of the most appropriate material (Polyethylene Terephthalate Glycol-modified (PETG)) to find the optimal stimulation input parameters for bone TE based on two reported in vitro studies.info:eu-repo/semantics/publishedVersio

Additive manufactured Poly("-caprolactone)-graphene scaffolds: Lamellar crystal orientation, mechanical properties and biological performance

Understanding the mechano–biological coupling mechanisms of biomaterials for tissue engineering is of major importance to assure proper scaffold performance in situ. Therefore, it is of paramount importance to establish correlations between biomaterials, their processing conditions, and their mechanical behaviour, as well as their biological performance. With this work, it was possible to infer a correlation between the addition of graphene nanoparticles (GPN) in a concentration of 0.25, 0.5, and 0.75% (w/w) (GPN0.25, GPN0.5, and GPN0.75, respectively) in three-dimensional poly("-caprolactone) (PCL)-based scaffolds, the extrusion-based processing parameters, and the lamellar crystal orientation through small-angle X-ray scattering experiments of extruded samples of PCL and PCL/GPN. Results revealed a significant impact on the scaffold’s mechanical properties to a maximum of 0.5% of GPN content, with a significant improvement in the compressive modulus of 59 MPa to 93 MPa. In vitro cell culture experiments showed the scaffold’s ability to support the adhesion and proliferation of L929 fibroblasts (fold increase of 28, 22, 23, and 13 at day 13 (in relation to day 1) for PCL, GPN0.25, GPN0.5, and GPN0.75, respectively) and bone marrow mesenchymal stem/stromal cells (seven-fold increase for all sample groups at day 21 in relation to day 1). Moreover, the cells maintained high viability, regular morphology, and migration capacity in all the different experimental groups, assuring the potential of PCL/GPN scaffolds for tissue engineering (TE) applications.info:eu-repo/semantics/publishedVersio

Time and spatially resolved operando small-angle X-ray scattering measurements during injection moulding of plastics

We recently introduced the possibility of performing operando small-angle X-ray scattering measurements using a novel industrially relevant injection moulding system for plastics. We show that useful time-resolving measurements can be performed with a time-cycle of 1 s and highlight the possible steps to reduce this to 0.5 s. We show how we can use the transmission measurements to provide a time marker when plastic first enters the mould cavity in the region probed by the incident X-ray beam. We show the opportunities provided by this experimental stage mounted on the NCD-SWEET beamline at ALBA to probe the reproducibility of the injection moulding system on different scales. The design of the equipment allowed for the development of the structure and the morphology to be evaluated in different parts of mould cavity, and we evaluated any differences in a rectangular mould cavity. We identified future prospects for this equipment in terms of novel mould heating and cooling systems and the opportunities for quantitatively evaluating radical approaches to injection moulding technology.This work was financially supported by the Fundação para a Ciência e a Tecnologia FCT/MCTES (PIDDAC) through the following Projects: MIT-EXPL/TDI/0044/2021, UIDB/04044/2020; UIDP/04044/2020; Associate Laboratory ARISE LA/P/0112/2020; PAMI—ROTEIRO/0328/2013 (No. 022158); plus EcoPlast, Materiais compósitos eco-sustentáveis para substituição dos plásticos convencionais, ref POCI-01-0247-FEDER-069002; and INNOV-AM funded by National Agency of Innovation M.A. is grateful for the support received from the Ministerio de Ciencia, Innovación y Universidades of Spain, with the mobility program of the grant “Ayudas para contratos predoctorales para la formación de doctoresas 2019”.  Peer ReviewedPostprint (published version