Investigation on material combination technique to enhance the anti-wrinkle and anti-vibration characteristics of the planar membrane reflector

In recent trends, membrane structure has increased its applications in space missions due to its significant advantages, such as light in weight, higher folding and packaging efficiency, ease of deployment, and low on-Board volume requirement. The wrinkling and low natural frequency of vibration are the major problems with the membrane structure. This research presents a novel methodology of Kapton-Kevlar material combination for a planar membrane reflector to enhance anti-vibration and anti-wrinkling capabilities of the membrane structure. The comparative study is made for the wrinkle area, RMS error, and natural frequency of vibration with the employed approach. This study provides new insights into a material combination technique to increase performance characteristics of the space-borne membrane reflectors. The outcome of the wrinkling analysis is compared and found to be consistent with the method available in the literature. From the simulation results, it is observed that wrinkles are reduced, and the natural frequency of vibration is also increased significantly with the proposed method.

Polymerization of Bacillus subtilis MreB on a lipid membrane reveals lateral co-polymerization of MreB paralogs and strong effects of cations on filament formation

Background MreB is a bacterial ortholog of actin and forms mobile filaments underneath the cell membrane, perpendicular to the long axis of the cell, which play a crucial role for cell shape maintenance. We wished to visualize Bacillus subtilis MreB in vitro and therefore established a protocol to obtain monomeric protein, which could be polymerized on a planar membrane system, or associated with large membrane vesicles. Results Using a planar membrane system and electron microscopy, we show that Bacillus subtilis MreB forms bundles of filaments, which can branch and fuse, with an average width of 70 nm. Fluorescence microscopy of non-polymerized YFP-MreB, CFP-Mbl and mCherry-MreBH proteins showed uniform binding to the membrane, suggesting that 2D diffusion along the membrane could facilitate filament formation. After addition of divalent magnesium and calcium ions, all three proteins formed highly disordered sheets of filaments that could split up or merge, such that at high protein concentration, MreB and its paralogs generated a network of filaments extending away from the membrane. Filament formation was positively affected by divalent ions and negatively by monovalent ions. YFP-MreB or CFP-Mbl also formed filaments between two adjacent membranes, which frequently has a curved appearance. New MreB, Mbl or MreBH monomers could add to the lateral side of preexisting filaments, and MreB paralogs co-polymerized, indicating direct lateral interaction between MreB paralogs. Conclusions Our data show that B. subtilis MreB paralogs do not easily form ordered filaments in vitro, possibly due to extensive lateral contacts, but can co-polymerise. Monomeric MreB, Mbl and MreBH uniformly bind to a membrane, and form irregular and frequently split up filamentous structures, facilitated by the addition of divalent ions, and counteracted by monovalent ions, suggesting that intracellular potassium levels may be one important factor to counteract extensive filament formation and filament splitting in vivo.

Polymerization of Bacillus Subtilis MreB on A Lipid Membrane Reveals Lateral Co-Polymerization of MreB Paralogs and Strong Effects of Cations on Filament Formation

Background MreB is a bacterial ortholog of actin and forms mobile filaments underneath the cell membrane, perpendicular to the long axis of the cell, which play a crucial role for cell shape maintenance. We wished to visualize Bacillus subtilis MreB in vitro and therefore established a protocol to obtain monomeric protein, which could be polymerized on a planar membrane system, or associated with large membrane vesicles. Results Using a planar membrane system and electron microscopy, we show that Bacillus subtilis MreB forms bundles of filaments, which can branch and fuse, with an average width of 70 nm. Fluorescence microscopy of non-polymerized YFP-MreB, CFP-Mbl and mCherry-MreBH proteins showed uniform binding to the membrane, suggesting that 2D diffusion along the membrane could facilitate filament formation. After addition of divalent ions, all three proteins formed highly disordered filaments that appeared to branch and fuse, such that at high protein concentration, MreB and its paralogs generated a network of filaments extending away from the membrane. Filament formation was positively affected by divalent ions and negatively by monovalent ions. YFP-MreB or CFP-Mbl also formed filaments between two adjacent membranes, which frequently has a curved appearance. New MreB, Mbl or MreBH monomers could add to the lateral side of preexisting filaments, and MreB paralogs co-polymerized, indicating direct lateral interaction between MreB paralogs. Conslusions Our data show that B. subtilis MreB paralogs do not easily form ordered filaments in vitro, possibly due to extensive lateral contacts, but can co-polymerase. Monomeric MreB, Mbl and MreBH uniformly bind to a membrane, and form irregular and frequently branched filamentous structures, facilitated by the addition of divalent ions, and counteracted by monovalent ions, suggesting that intracellular potassium levels may be one important factor to counteract extensive filament formation and filament branching in vivo.