| 11. |
- 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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| 12. |
- Isberg, Jan, et al.
(författare)
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Generation, transport and detection of valley-polarized electrons in diamond
- 2013
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Ingår i: Nature Materials. - 1476-1122 .- 1476-4660. ; 12:8, s. 760-764
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Tidskriftsartikel (refereegranskat)abstract
- Standard electronic devices encode bits of information by controlling the amount of electric charge in the circuits. Alternatively, it is possible to make devices that rely on other properties of electrons than their charge. For example, spintronic devices make use of the electron spin angular momentum as a carrier of information. A new concept is valleytronics in which information is encoded by the valley quantum number of the electron. The analogy between the valley and spin degrees of freedom also implies the possibility of valley-based quantum computing. In this Article, we demonstrate for the first time generation, transport ( across macroscopic distances) and detection of valley-polarized electrons in bulk diamond with a relaxation time of 300 ns at 77 K. We anticipate that these results will form the basis for the development of integrated valleytronic devices.
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| 13. |
- Käll, Mikael, 1963
(författare)
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Plasmonic nanosensors: Inverse sensitivity
- 2012
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Ingår i: Nature Materials. - : Springer Science and Business Media LLC. - 1476-4660 .- 1476-1122. ; 11:7, s. 570-571
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 14. |
- Luo, Yongkang, et al.
(författare)
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Heavy-fermion quantum criticality and destruction of the Kondo effect in a nickel oxypnictide
- 2014
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Ingår i: Nature Materials. - : Nature Publishing Group. - 1476-1122 .- 1476-4660. ; 13:8, s. 777-781
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Tidskriftsartikel (refereegranskat)abstract
- A quantum critical point arises at a continuous transformation between distinct phases of matter at zero temperature. Studies in antiferromagnetic heavy-fermion materials have revealed that quantum criticality has several classes, with an unconventional type that involves a critical destruction of the Kondo entanglement(1,2). To understand such varieties, it is important to extend the materials basis beyond the usual setting of intermetallic compounds. Here we show that a nickel oxypnictide, CeNiAsO, exhibits a heavy-fermion antiferromagnetic quantum critical point as a function of either pressure or P/As substitution. At the quantum critical point, non-Fermi-liquid behaviour appears, which is accompanied by a divergent effective carrier mass. Across the quantum critical point, the low-temperature Hall coefficient undergoes a rapid sign change, suggesting a sudden jump of the Fermi surface and a destruction of the Kondo effect(3,4). Our results imply that the enormous materials basis for the oxypnictides, which has been so crucial in the search for high-temperature superconductivity, will also play a vital role in the effort to establish the universality classes of quantum criticality in strongly correlated electron systems.
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| 15. |
- Nordblad, Per
(författare)
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MAGNETOCALORIC MATERIALS Strained relations
- 2013
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Ingår i: Nature Materials. - : Springer Science and Business Media LLC. - 1476-1122 .- 1476-4660. ; 12:1, s. 11-12
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 16. |
- Ohlin, C. Andre, et al.
(författare)
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Dissolution of insulating oxide materials at the molecular scale
- 2010
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Ingår i: Nature Materials. - 1476-1122 .- 1476-4660. ; 9:1, s. 11-19
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Forskningsöversikt (refereegranskat)abstract
- Our understanding of mineral and glass dissolution has advanced from simple thermodynamic treatments to models that emphasize adsorbate structures. This evolution was driven by the idea that the best understanding is built at the molecular level. Now, it is clear that the molecular questions cannot be answered uniquely with dissolution experiments. At the surface it is unclear which functional groups are present, how they are arranged, and how they interact with each other and with solutes as the key bonds are activated. An alternative approach has developed whereby reactions are studied with nanometre-sized aqueous oxide ions that serve as models for the more complicated oxide interface. For these ions, establishing the structure is not a research problem in itself, and bond ruptures and dissociations can be followed with much confidence. We review the field from bulk-dissolution kinetics to the new isotope-exchange experiments in large oxide ions.
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| 17. |
- Ojamäe, Lars
(författare)
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CRYSTALLINE ICE Amorphous on the surface
- 2011
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Ingår i: Nature Materials. - : Nature Publishing Group. - 1476-1122 .- 1476-4660. ; 10:10, s. 725-726
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Crystalline ice surfaces are found to exhibit an unusually large spread of vacancy formation energies, akin to an amorphous material. The finding has implications for the fundamental understanding of electrostatically frustrated surfaces and for the reactivity and catalytic properties of atmospheric ice. Watkins et al. have found that even for a perfect ice surface, a clean-cut surface where the oxygen atoms are ordered in a hexagonal lattice, the energy needed to form a vacancy varies greatly depending on the water molecule removed. They found that at interfaces, nearest-neighbor water molecules cannot satisfy all hydrogen bonds, and thus some of the molecules exhibit dangling OH bonds. The findings of Watkins and co-authors imply that ice may possess more surface vacancies than expected. The ab initio molecular dynamics simulations of model ice surfaces show that surface molecules can be thermally activated below the model's melting point to form vacancies and adsorbed molecules at the surface.
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| 18. |
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| 19. |
- Roeling, Erik M., et al.
(författare)
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Organic electronic ratchets doing work
- 2011
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Ingår i: Nature Materials. - : Nature Publishing Group. - 1476-1122 .- 1476-4660. ; 10:1, s. 51-55
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Tidskriftsartikel (refereegranskat)abstract
- The possibility to extract work from periodic, undirected forces has intrigued scientists for over a century-in particular, the rectification of undirected motion of particles by ratchet potentials, which are periodic but asymmetric functions. Introduced by Smoluchowski and Feynman(1,2) to study the (dis)ability to generate motion from an equilibrium situation, ratchets operate out of equilibrium, where the second law of thermodynamics no longer applies. Although ratchet systems have been both identified in nature(3,4) and used in the laboratory for the directed motion of microscopic objects(5-9), electronic ratchets(10-13) have been of limited use, as they typically operate at cryogenic temperatures and generate subnanoampere currents and submillivolt voltages(10-14). Here, we present organic electronic ratchets that operate up to radio frequencies at room temperature and generate currents and voltages that are orders of magnitude larger. This enables their use as a d.c. power source. We integrated the ratchets into logic circuits, in which they act as the d.c. equivalent of the a. c. transformer, and generate enough power to drive the circuitry. Our findings show that electronic ratchets may be of actual use.
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| 20. |
- Siahrostami, Samira, 1982, et al.
(författare)
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Enabling direct H2O2 production through rational electrocatalyst design
- 2013
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Ingår i: Nature Materials. - : Springer Science and Business Media LLC. - 1476-4660 .- 1476-1122. ; 12:12, s. 1137-1143
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Tidskriftsartikel (refereegranskat)abstract
- Future generations require more efficient and localized processes for energy conversion and chemical synthesis. The continuous on-site production of hydrogen peroxide would provide an attractive alternative to the present state-of-the-art, which is based on the complex anthraquinone process. The electrochemical reduction of oxygen to hydrogen peroxide is a particularly promising means of achieving this aim. However, it would require active, selective and stable materials to catalyse the reaction. Although progress has been made in this respect, further improvements through the development of new electrocatalysts are needed. Using density functional theory calculations, we identify Pt-Hg as a promising candidate. Electrochemical measurements on Pt-Hg nanoparticles show more than an order of magnitude improvement in mass activity, that is, Ag-1 precious metal, for H2O2 production, over the best performing catalysts in the literature.
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