| 1. |
- Andersson, Mathias H., et al.
(författare)
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Epibenthic colonization of concrete and steel pilingsin a cold-temperate embayment : a feld experiment
- 2009
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Ingår i: Helgoland Marine Research. - : Springer Science and Business Media LLC. - 1438-387X .- 1438-3888. ; 63:3, s. 249-260
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Tidskriftsartikel (refereegranskat)abstract
- With large-scale development of offshore wind farms, vertical structures are becoming more common in open water areas. To examine how vertical structures of different materials may be colonized by epibenthic organisms, an experiment was carried out using steel and concrete pilings constructed to resemble those commonly used in wind farm constructions as well as in bridges, jetties and oil platforms. The early recruitment and succession of the epibenthic communities were sampled once a month for the first 5 months and then again after 1 year. Further, the fish assemblages associated with the pillars were sampled and compared to natural areas. The main epibenthic species groups, in terms of coverage, diVered between the two materials at five out of six sampling occasions. Dominant organisms on steel pillars were the barnacle Balanus improvisus,the calcareous tubeworm Pomatoceros triqueter and the tunicate Ciona intestinalis. On the concrete pillars, the hydroid Laomedea sp. and the tunicates Corella parallelogramma and Ascidiella spp. dominated. However, there was no different in coverage at different heights on the pillars or in biomass and species abundance at different directions (north-east or south-west) 5 months after submergence. Fish showed overall higher abundances and species numbers on the pillars (but no difference between steel and concrete)compared to the surrounding soft bottom habitats but not compared to natural vertical rock walls. Two species were attracted to the pillars, indicating a reef effect; Gobiusculus flavescens and Ctenolabrus rupestris. The bottom-dwelling gobies, Pomatoschistus spp., did not show such preferences.
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| 2. |
- Börjesson, Karl, 1982, et al.
(författare)
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Nucleic Acid Base Analog FRET-Pair Facilitating Detailed Structural Measurements in Nucleic Acid Containing Systems
- 2009
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 131:12, s. 4288-4293
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Tidskriftsartikel (refereegranskat)abstract
- We present the first nucleobase analog fluorescence resonance energy transfer (FRET)-pair. The pair consists of tC O , 1,3-diaza-2- oxophenoxazine, as an energy donor and the newly developed tC nitro , 7-nitro-1,3-diaza-2-oxophenothiazine, as an energy acceptor. The FRET-pair successfully monitors distances covering up to more than one turn of the DNA duplex. Importantly, we show that the rigid stacking of the two base analogs, and consequently excellent control of their exact positions and orientations, results in a high control of the orientation factor and hence very distinct FRET changes as the number of bases separating tC O and tCnitro is varied. A set of DNA strands containing the FRET-pair at wisely chosen locations will, thus, make it possible to accurately distinguish distance- from orientation-changes using FRET. In combination with the good nucleobase analog properties, this points toward detailed studies of the inherent dynamics of nucleic acid structures. Moreover, the placement of FRET-pair chromophores inside the base stack will be a great advantage in studies where other (biomacro)molecules interact with the nucleic acid. Lastly, our study gives possibly the first truly solid experimental support to the dependence of energy transfer efficiency on orientation of involved transition dipoles as predicted by the Forster theory. © 2009 American Chemical Society.
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| 3. |
- Dueñas, S., et al.
(författare)
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Experimental investigation of the electrical properties of atomic layer deposited hafnium-rich silicate films on n-type silicon
- 2006
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 100:9, s. 094107-
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Tidskriftsartikel (refereegranskat)abstract
- This work examines the structural and electrical properties of HfSixOy film based metal-insulator-semiconductor capacitors by means of x-ray diffraction, x-ray photoelectron spectroscopy, capacitance-voltage (C-V), deep level transient spectroscopy, and conductance transient (G-t) techniques. Hafnium-rich silicate films were atomic layer deposited onto HF-etched or SiO2 covered silicon. Although as-deposited samples exhibit high interfacial state and disorder-induced gap state densities, a postdeposition thermal annealing in vacuum under N2 flow for 1 min at temperatures between 600 and 730 °C clearly improves the interface quality. Marked crystallization and phase separation occurred at 800 °C, increasing the structural heterogeneity and defect density in the dielectric oxide layers.
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| 4. |
- Fang, C.M., et al.
(författare)
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General trend of the mechanical properties of the ternary carbides M3SiC2 (M=transition metal)
- 2006
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 74:5, s. 054106-
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Tidskriftsartikel (refereegranskat)abstract
- We present results from first-principles calculations of ternary transition metal carbides in the M3SiC2 series (where M=early transition metal). We predict structural and mechanical properties of these new MN+1AXN phases. The bulk modulus of the ternary carbides, M3SiC2, are in the calculations found to be proportional to the bulk modulus of the corresponding binary carbides, MC. We have analyzed this behavior using a simple, nearest-neighbor bond model, as well as from first-principles total energy calculations and have found that it is caused by a considerably weaker M-Si bond compared to the M-C bond.
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| 5. |
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| 6. |
- Lindgren, Malin, et al.
(författare)
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Fondue and transglutaminase in the Drosophila larval clot
- 2008
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Ingår i: Journal of insect physiology. - : Elsevier BV. - 0022-1910 .- 1879-1611. ; 54:3, s. 586-592
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Tidskriftsartikel (refereegranskat)abstract
- Hemolymph coagulation is vital for larval hemostasis and important in immunity, yet the molecular basis of coagulation is not well understood in insects. Of the larval clotting factors identified in Drosophila, Fondue is not conserved in other insects, but is notable for its effects on the clot's physical properties, a possible function in the cuticle, and for being a substrate of transglutaminase. Transglutaminase is the only mammalian clotting factor found in Drosophila, and as it acts in coagulation in other invertebrates, it is also likely to be important in clotting in Drosophila. Here we describe a Fondue-GFP fusion construct that labels the cuticle and clot, and show that chemical inhibition and RNAi knockdown of the Drosophila transglutaminase gene affect clot properties and composition in ways similar to knockdown of the fon gene. Thus, Fondue appears to be incorporated into the cuticle and is a key transglutaminase substrate in the clot. This is also the first direct functional confirmation that transglutaminase acts in coagulation in Drosophila.
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| 7. |
- Lundberg, Erik, 1981, et al.
(författare)
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Addressable molecular node assembly - high information density DNA nanostructures
- 2008
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Ingår i: Nucleic acids symposium series (2004). - 1746-8272. ; :52, s. 683-684
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Tidskriftsartikel (refereegranskat)abstract
- The inherent self-assembly properties of DNA make it ideal in nanotechnology. We present a fully addressable DNA nanostructure with the smallest possible unit cell, a hexagon with a side-length of only 3.4 nm.(2,3) Using novel three-way oligonucleotides, where each side has a unique double-stranded DNA sequence that can be assigned a specific address, we will build a non-repetitive two-dimensional grid.
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| 8. |
- Magnuson, Martin, et al.
(författare)
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Electronic structure and chemical bonding in Ti2AlC investigated by soft x-ray emission spectroscopy
- 2006
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 74:195108
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Tidskriftsartikel (refereegranskat)abstract
- Theelectronic structure of the nanolaminated transition metal carbide Ti2AlC hasbeen investigated by bulk-sensitive soft x-ray emission spectroscopy. The measuredTi L, C K, and Al L emission spectra arecompared with calculated spectra using ab initio density-functional theory includingdipole matrix elements. The detailed investigation of the electronic structureand chemical bonding provides increased understanding of the physical propertiesof this type of nanolaminates. Three different types of bondregions are identified: The relatively weak Ti 3d–Al 3p bond1 eV below the Fermi level and the Ti 3d–C 2pand Ti 3d–C 2s bonds which are stronger and deeperin energy are observed around 2.5 and 10 eV below theFermi level, respectively. A strongly modified spectral shape of the3s final states in comparison to pure Al is detectedfor the intercalated Al monolayers indirectly reflecting the Ti 3d–Al3p hybridization. The differences between the electronic and crystal structuresof Ti2AlC, Ti3AlC2, and TiC are discussed in relation tothe number of Al layers per Ti layer in thetwo former systems and the corresponding change of the unusualmaterials properties.
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| 9. |
- Tumpane, John, 1983, et al.
(författare)
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Triplex addressability as a basis for functional DNA nanostructures
- 2007
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 7:12, s. 3832-3839
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Tidskriftsartikel (refereegranskat)abstract
- Here, we present the formation of a fully addressable DNA nanostructure that shows the potential to be exploited as, for example, an information storage device based on pH-driven triplex strand formation or nanoscale circuits based on electron transfer, The nanostructure is composed of two adjacent hexagonal unit cells (analogous to naphthalene) in which each of the eleven edges has a unique double-stranded DNA sequence, constructed using novel three-way oligonucleotides. This allows each ten base-pair side, just 3.4 nm in length, to be assigned a specific address according to its sequence. Such constructs are therefore an ideal precursor to a nonrepetitive two-dimensional grid on which the "addresses" are located at a precise and known position. Triplex recognition of these addresses could function as a simple yet efficient means of information storage and retrieval. Future applications that may be envisaged include nanoscale circuits as well as subnanometer precision in nanoparticle templating. Characterization of these precursor nanostructures and their reversible targeting by triplex strand formation is shown here using gel electrophoresis, atomic force microscopy, and fluorescence resonance energy transfer (FRET) measurements. The durability of the system to repeated cycling of pH switching is also confirmed by the FRET studies.
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| 10. |
- Widestrand, Åsa, 1978, et al.
(författare)
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Increased neurogenesis and astrogenesis from neural progenitor cells grafted in the hippocampus of GFAP-/- Vim-/- mice.
- 2007
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Ingår i: Stem cells (Dayton, Ohio). - : Oxford University Press (OUP). - 1549-4918 .- 1066-5099. ; 25:10, s. 2619-27
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Tidskriftsartikel (refereegranskat)abstract
- After neurotrauma, ischemia, or neurodegenerative disease, astrocytes upregulate their expression of the intermediate filament proteins glial fibrillary acidic protein (GFAP), vimentin (Vim), and nestin. This response, reactive gliosis, is attenuated in GFAP(-/-)Vim(-/-) mice, resulting in the promotion of synaptic regeneration after neurotrauma and improved integration of retinal grafts. Here we assessed whether GFAP(-/-)Vim(-/-) astrocytes affect the differentiation of neural progenitor cells. In coculture with GFAP(-/-)Vim(-/-) astrocytes, neural progenitor cells increased neurogenesis by 65% and astrogenesis by 124%. At 35 days after transplantation of neural progenitor cells into the hippocampus, adult GFAP(-/-)Vim(-/-) mice had more transplant-derived neurons and astrocytes than wild-type controls, as well as increased branching of neurite-like processes on transplanted cells. Wnt3 immunoreactivity was readily detected in hippocampal astrocytes in wild-type but not in GFAP(-/-)Vim(-/-) mice. These findings suggest that GFAP(-/-)Vim(-/-) astrocytes allow more neural progenitor cell-derived neurons and astrocytes to survive weeks after transplantation. Thus, reactive gliosis may adversely affect the integration of transplanted neural progenitor cells in the brain. Disclosure of potential conflicts of interest is found at the end of this article.
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