| 1. |
- Cornelissen, R., et al.
(författare)
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The Cell Envelope Structure of Cable Bacteria
- 2018
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Ingår i: Frontiers in Microbiology. - : Frontiers Media SA. - 1664-302X. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Cable bacteria are long, multicellular micro-organisms that are capable of transporting electrons from cell to cell along the longitudinal axis of their centimeter-long filaments. The conductive structures that mediate this long-distance electron transport are thought to be located in the cell envelope. Therefore, this study examines in detail the architecture of the cell envelope of cable bacterium filaments by combining different sample preparation methods (chemical fixation, resin-embedding, and cryo-fixation) with a portfolio of imaging techniques (scanning electron microscopy, transmission electron microscopy and tomography, focused ion beam scanning electron microscopy, and atomic force microscopy). We systematically imaged intact filaments with varying diameters. In addition, we investigated the periplasmic fiber sheath that remains after the cytoplasm and membranes were removed by chemical extraction. Based on these investigations, we present a quantitative structural model of a cable bacterium. Cable bacteria build their cell envelope by a parallel concatenation of ridge compartments that have a standard size. Larger diameter filaments simply incorporate more parallel ridge compartments. Each ridge compartment contains a similar to 50 nm diameter fiber in the periplasmic space. These fibers are continuous across cell-to-cell junctions, which display a conspicuous cartwheel structure that is likely made by invaginations of the outer cell membrane around the periplasmic fibers. The continuity of the periplasmic fibers across cells makes them a prime candidate for the sought-after electron conducting structure in cable bacteria.
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| 2. |
- De Sitter, K, et al.
(författare)
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Silica filled poly(1-trimethylsilyl-1-propyne) nanocomposite membranes: Relation between the transport of gases and structural characteristics
- 2006
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Ingår i: Journal of Membrane Science. - : Elsevier BV. - 0376-7388. ; 278:1-2, s. 83-91
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Tidskriftsartikel (refereegranskat)abstract
- The performance of poly(1-trimethylsilyl-1-propyne) (PTMSP)/silica nanocomposites was studied for membranes with a filler content between 0 and 50 wt%. An increase in permeability and a decrease in vapor selectivity was measured with increasing filler content. The free volume sizes and interstitial mesopore sizes of the composites were determined by use of positron annihilation lifetime spectroscopy (PALS). In addition to an increase in large free volume size with increasing filler content, interstitial mesopores were observed in all PTMSP/silica nanocomposites. The size of these interstitial cavities, located between the particles of a silica agglomerate, was increasing with increasing filler concentration. The presence of these agglomerates was visualized by TEM. The existence of the cavities was confirmed by nitrogen adsorption measurements. The hydrogen, nitrogen and propane permeability was clearly correlated with the size of the interstitial mesopores. (c) 2005 Elsevier B.V. All rights reserved.
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| 3. |
- De Sitter, Kristien, et al.
(författare)
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Silica filled poly(4-methyl-2-pentyne) nanocomposite membranes: Similarities and differences with poly(1-trimethylsilyl-1-propyne)-silica systems
- 2008
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Ingår i: Journal of Membrane Science. - : Elsevier BV. - 0376-7388. ; 321:2, s. 284-292
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Tidskriftsartikel (refereegranskat)abstract
- The performance of poly(4-methyl-2-pentyne) (PMP)/silica nanocomposites was studied for membranes with a filler content between 10 and 40 wt%. An increase in permeability and a constant vapor selectivity were measured with increasing filler content. The constant selectivity was in contrast to earlier published results for silica filled poly(l-trimethylsilyl-l-propyne) (PTSMP) membranes. Therefore, a comparison between both materials was made. Free volume sizes and interstitial mesopore sizes were determined by use of positron annihilation lifetime spectroscopy (PALS) and image analysis was performed on transmission electron microscopy (TEM) pictures of both materials. Although both materials possessed interstitial mesopores, a difference in membrane structure was noticed, explaining the difference in membrane performance. (c) 2008 Elsevier B.V. All rights reserved.
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