Experimental study of gliding arc plasma channel motion: buoyancy and gas flow phenomena under normal and hypergravity conditions

The details of plasma channel motion are investigated by frame-by-frame image analysis of high speed recording of a gliding arc. The gliding arc is operated in several noble gases at various flow rates, voltages and artificial gravity levels. Several peculiarities in evolution of individual glides are observed, described and discussed, such as accelerating motion of plasma channel or shortcutting events of various kinds. Statistics of averaged parameters are significantly different for buoyancy and gas drag dominated regimes, which is put into relation with differing flow patterns for hypergravity and high gas flow

Use of microgravity simulators for plant biological studies

16 p.-4 fig.-2 tab.Simulated microgravity and partial gravity research on Earth is highly convenient for every space biology researcher due to limitations of access to spacefl ight. However, the use of ground-based facilities for microgravity simulation is far from simple. Microgravity simulation usually results in the need to consider additional environmental parameters which appear as secondary effects in the generation of altered gravity. These secondary effects may interfere with gravity alteration in the changes observed in the biological processes under study. Furthermore, ground-based facilities are also capable of generating hypergravity or fractional gravity conditions, which are worth being tested and compared with the results of microgravity exposure. Multiple technologies (2D clinorotation, random positioning machines, magnetic levitators or centrifuges), experimental hardware (proper use of containers and substrates for the seedlings or cell cultures), and experimental requirements (some life support/environmental parameters are more diffi cult to provide in certain facilities) should be collectively considered in defi ning the optimal experimental design that will allow us to anticipate, modify, or redefi ne the fi ndings provided by the scarce spacefl ight opportunities that have been (and will be) available.Most of the results and comments included in this book chapter have been the consequence of the authors’ participation in “ESA Access to GBF” Project Nos. 4200022650 and 4000105761 in close collaboration with GBF managers Dr. van Loon (DESC), Dr. Hemmersbach(DLR), Dr. Pereda-Loth (Toulouse University), Dr. Hill (Nottingham University), and Dr. Christianen (Nijmegen University). Work performed in the authors’ laboratory was financially supported by the Spanish Plan Nacional de Investigación Científica y Desarrollo Tecnológico, Grant Ref. No. AYA2012-33982.Peer reviewe

Effects of hypergravity on the angiogenic potential of endothelial cells

Angiogenesis, the formation of blood vessels from pre-existing ones, is a key event in pathology, including cancer progression, but also in homeostasis and regeneration. As the phenotype of endothelial cells (ECs) is continuously regulated by local biomechanical forces, studying endothelial behaviour in altered gravity might contribute to new insights towards angiogenesis modu- lation. This study aimed at characterizing EC behaviour after hypergravity exposure (more than 1g), with special focus on cytoskeleton architecture and capillary-like structure formation. Herein, human umbilical vein ECs (HUVECs) were cultured under two-dimensional and three-dimensional conditions at 3g and 10g for 4 and 16 h inside the large diameter centrifuge at the European Space Research and Technology Centre (ESTEC) of the European Space Agency. Although no significant tendency regarding cyto- skeleton organization was observed for cells exposed to high gâ s, a slight loss of the perinuclear localization of b-tubulin was observed for cells exposed to 3g with less pronounced peripheral bodies of actin when compared with 1g control cells. Additionally, hypergravity exposure decreased the assembly of HUVECs into capillary-like structures, with a 10g level significantly reducing their organization capacity. In conclusion, short-term hypergravity seems to affect EC phenotype and their angiogenic potential in a time and g-level-dependent manner. Funding. This work was supported by the Spin Your Thesis! 2014 programme, organized by ESA Education Office. Additional funding include the European Regional Development Fund (ERDF) through the Programa Operacional Factores de Competitividade – COMPETE, and by Portuguese funds through FCT-Fundação para a Ciência e a Tecnologia in the framework of FCT-POPH-FSE, the research grant PEst-C/SAU/LA0002/2011, and co-financed by the North Portugal Regional Operational Programme (ON.2-O Novo Norte) in the framework of the project NORTE-01-0145-FEDER-000012, under the National Strategic Reference Framework (NSRF). Acknowledgements. The experiments reported here were performed in the framework of the Spin Your Thesis! 2014 programme, organized by ESA Education Office. The authors are grateful to staff of ESA Education Office, Natacha Callens and Lily Ha, for support, and to Alan Dowson for the technical support before and during the campaign. R.C.-A. acknowledges the PhD grant SFRH/BD/96593/2013 from FCT-Fundação para a Ciência e a Tecnologia