2022, Pyttlik, Andrea, Kuttich, Björn, Kraus, Tobias

Gravity can affect the agglomeration of nanoparticles by changing convection and sedimentation. The temperature-induced agglomeration of hexadecanethiol-capped gold nanoparticles in microgravity (µ g) is studied at the ZARM (Center of Applied Space Technology and Microgravity) drop tower and compared to their agglomeration on the ground (1 g). Nonpolar nanoparticles with a hydrodynamic diameter of 13 nm are dispersed in tetradecane, rapidly cooled from 70 to 10 °C to induce agglomeration, and observed by dynamic light scattering at a time resolution of 1 s. The mean hydrodynamic diameters of the agglomerates formed after 8 s in microgravity are 3 times (for low initial concentrations) to 5 times (at high initial concentrations) larger than on the ground. The observations are consistent with an agglomeration process that is closer to the reaction limit on thground and closer to the diffusion limit in microgravity.

2003, Fortov, V. E., Nefedov, A. P., Vaulina, O. S., Petrov, O. F., Dranzhevski, I. E., Lipaev, A. M., Semenov, Yu. P.

In this paper the results of experimental investigation of the dynamic behaviour of macroparticles charged via photoemission are presented. The experimental data have been obtained for bronze particles subjected to solar radiation under conditions of microgravity (on board the Mir space station). The distribution of velocity, temperatures and charge, as well as the friction coefficient and diffusion constants, have been found. The analysis of the results obtained has shown that the polarization effects of opposite charges may appreciably influence the transport processes in a two-component electron-dust plasma, consisting of positively charged dust and emitted electrons.

2013, Lee, Juseok

The first part of this thesis is dealing with gravity effect on the synthesis of biphasic core/shell Al/Al2O3 composites. By chemical vapor deposition of the precursor [tBuOAlH2]2 at 400°C, only spherical nanoparticles were observed on the substrate surface. The formation of nanowires was observed at 600°C. It is a good agreement with our previous results on earth condition and there is no gravity impact on the chemical reaction. At increased gravity levels, the nanoparticles formed large clusters and the nanowires showed bundle formation while the nanowires at microgravity have predominantly linear structures. It is proposed that the chaotic nature of nanowires and cluster formation of nanoparticles were caused by a dominance of gravity over the thermal creep. In the second part the use of Al/Al2O3 nanowire layers for bio applications is considered. Contact cell guidance and alignment were studied to understand how cells recognize and respond to certain surface patterns. Linear micro channels were created on Al/Al2O3 layer by direct laser writing and laser interference patterning. Although surface topography was altered, the surface chemistry was always identical (Al2O3) due to the unique core/shell nature of Al/Al2O3 nanowires. Human osteoblast, normal human dermal fibroblast and neuronal cells were cultured and investigated. The results indicate that different cell types show diverse responses to the topography independent from the surface chemistry of the material.

2003, Gozadinos, G., Ivlev, A. V., Boeuf, J. P.

A numerical model is presented to simulate steady states of complex ('dusty') plasmas under microgravity conditions. The model uses a fluid description for the plasma as well as for the dust microparticles. This is achieved by using an appropriate equation of state for the crystalline phase of the dust. The only forces assumed to act on the dust particles are the electric force, ion drag and pressure gradients. The model is used to study the formation of the stable 'void' present in recent microgravity experiments. The structure of the dust clouds when the void is present is examined and explained.