Germination of Arabidopsis Seed in Space and in Simulated Microgravity: Alterations in Root Cell Growth and Proliferation

Changes have been reported in the pattern of gene expression in Arabidopsis on exposure to microgravity. Plant cell growth and proliferation are functions that are potentially affected by such changes in gene expression. In the present investigation, the cell proliferation rate, the regulation of cell cycle progression and the rate of ribosome biogenesis (this latter taken to estimate cell growth) have been studied using morphometric markers or parameters evaluated by light and electron microscopy in real microgravity on the International Space Station (ISS) and in ground-based simulated microgravity, using the Random Positioning Machine and the Magnetic Levitation Instrument. Results showed enhanced cell proliferation but depleted cell growth in both real and simulated microgravity, indicating that the two processes are uncoupled, unlike the situation under normal gravity on Earth in which they are strictly co-ordinated events. It is concluded that microgravity is an important stress condition for plant cells compared to normal ground gravity conditions.     

Poly(dopamine) assisted deposition of adherent PPy film on Ti substrate

This study aims to address an issue to a subject that is still less present in literature: the adherence of polypyrrole (PPy) films on bioinert substrate. The poly(dopamine) (PDA) assisted deposition of PPy film on titanium substrate was performed in two steps. The chemical self-polymerization of dopamine was performed as a preliminary step from dopamine in Tris buffer solution on titanium substrate. Then, the resulted poly(dopamine) layer consisting of anchors with strong interactions with Ti surface was a new suitable substrate for polypyrrole film electrochemical deposition. The new PDA–PPy films were characterized in terms of interest properties for the desired biomedical applications: adherence, electrochemical stability of PDA–PPy film, wettability, topography, morphology and antibacterial effect. The poly(dopamine) assisted deposition of PPy film has been shown to be a facile and efficient route to improve the adhesion of PPy film on titanium maintaining or improving the properties of polymeric film.     

An insight on the effect of rubbing textile fiber on morphology of some semi-alicyclic polyimides for liquid crystal orientation

Two semi-alicyclic PIs were prepared from bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BOCA) and the aromatic diamines: 4,4′-oxydianiline (ODA) or 4-(4-{[4-(4-aminophenoxy)phenyl]sulfonyl}phenoxy)aniline (pBAPS). The obtained films are transparent in visible domain, having a cut-off wavelength of 294 nm for poly(BOCA–ODA) and 264 nm for poly(BOCA– p BAPS), respectively. Atomic force microscopy images indicate a better surface organization after rubbing with cotton velvet (V_C) comparatively with cellulose diacetate (V_CD). Contact angle measurements reveal a slight increase of hydrophobicity after patterning as a result of dipolar forces intensification and geometrical constraints of the macromolecular chains. The alignment properties of both PIs, tested with N-(4-methoxybenzylidene)-4-butylaniline, are more obviously for processing with V_C. Also, the contrast between the dark and bright states is higher for poly(BOCA– p BAPS)/V_C comparatively with poly(BOCA–ODA)/V_CD, since its larger surface malleability generates deeper microgrooves.