| 1. |
- Gözen, Irep, 1980, et al.
(författare)
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Fractal avalanche ruptures in biological membranes
- 2010
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Ingår i: Nature Materials. - 1476-4660 .- 1476-1122. ; 9:11, s. 908-912
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Tidskriftsartikel (refereegranskat)abstract
- Bilayer membranes envelope cells as well as organelles, and constitute the most ubiquitous biological material found in all branches of the phylogenetic tree. Cell membrane rupture is an important biological process, and substantial rupture rates are found in skeletal and cardiac muscle cells under a mechanical load(1). Rupture can also be induced by processes such as cell death(2), and active cell membrane repair mechanisms are essential to preserve cell integrity(3). Pore formation in cell membranes is also at the heart of many biomedical applications such as in drug, gene and short interfering RNA delivery(4). Membrane rupture dynamics has been studied in bilayer vesicles under tensile stress(5-8), which consistently produce circular pores(5,6). We observed very different rupture mechanics in bilayer membranes spreading on solid supports: in one instance fingering instabilities were seen resulting in floral-like pores and in another, the rupture proceeded in a series of rapid avalanches causing fractal membrane fragmentation. The intermittent character of rupture evolution and the broad distribution in avalanche sizes is consistent with crackling-noise dynamics(9). Such noisy dynamics appear in fracture of solid disordered materials(10), in dislocation avalanches in plastic deformations(11) and domain wall magnetization avalanches(12). We also observed similar fractal rupture mechanics in spreading cell membranes.
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| 2. |
- Jesorka, Aldo, 1967, et al.
(författare)
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Controlling Chemistry in Dynamic Nanoscale Systems
- 2010
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Ingår i: Springer Series in Chemical Physics. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 0172-6218. - 9783642025969 ; 96, s. 449-468
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The biological cell, the fundamental building block of the living world, is a complex maze of compartmentalized biochemical reactors that embed tens of thousands of chemical reactions running in parallel. Several, if not all, reactors are systematically interconnected by a web of nanofluidic transporters, such as nanotubes, vesicles, and membrane pores with ever-changing shapes and structures [1]. To initiate, terminate, or control chemical reactions, small-scale poly-/pleiomorphic systems undergo rapid and violent shape changes with energy barriers close to kBT , where, due to the small dimensions, diffusional mixing of reactants is rapid. The geometry, i.e. volume, and shape changes can be utilized to control both kinetic and thermodynamic properties of the system. This is in sharp contrast to the man-made macroscopic bioreactors, in which mixing of reactants is aided by mechanical means, such as stirring or sonication, under the assumption that reactions take place in volumes that do not change over time. Such reaction volumes are compact, like a sphere, a cube, or a cylinder, and do not provide for variation of shape. Ordinarily, reaction rates, mechanisms, and thermodynamic properties of chemical reactions in condensed media are based on these assumptions. A number of important questions and challenges arise from these facts. For example, how will we achieve fundamental understanding of how reactor shape affects chemistry on the nanoscale, how do we develop appropriate and powerful experimental model systems, and last but not least what impact will this knowledge have on the design and function of nanotechnological devices with new operation modes derived from natural principles.
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