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| 3. |
- Lindgren, Arne G., et al.
(författare)
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International stroke genetics consortium recommendations for studies of genetics of stroke outcome and recovery
- 2022
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Ingår i: International Journal of Stroke. - : SAGE Publications. - 1747-4930 .- 1747-4949. ; 17:3, s. 260-268
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Tidskriftsartikel (refereegranskat)abstract
- Numerous biological mechanisms contribute to outcome after stroke, including brain injury, inflammation, and repair mechanisms. Clinical genetic studies have the potential to discover biological mechanisms affecting stroke recovery in humans and identify intervention targets. Large sample sizes are needed to detect commonly occurring genetic variations related to stroke brain injury and recovery. However, this usually requires combining data from multiple studies where consistent terminology, methodology, and data collection timelines are essential. Our group of expert stroke and rehabilitation clinicians and researchers with knowledge in genetics of stroke recovery here present recommendations for harmonizing phenotype data with focus on measures suitable for multicenter genetic studies of ischemic stroke brain injury and recovery. Our recommendations have been endorsed by the International Stroke Genetics Consortium.
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| 5. |
- Bhattacharya, K., et al.
(författare)
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Lactoperoxidase-mediated degradation of single-walled carbon nanotubes in the presence of pulmonary surfactant
- 2015
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Ingår i: Carbon. - : Elsevier BV. - 0008-6223 .- 1873-3891. ; 91, s. 506-517
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Tidskriftsartikel (refereegranskat)abstract
- Carbon nanotubes (CNTs) may elicit inflammatory responses following pulmonary exposure. Conversely, enzymatic biodegradation of CNTs by inflammatory cells has also been reported. The aim of this study was to study the degradation of oxidized single-walled CNTs (ox-SWCNTs) by lactoperoxidase (LPO), a secreted peroxidase present in the airways, and whether pulmonary surfactant affects this biodegradation. To this end, ox-SWCNTs were incubated in vitro with recombinant bovine LPO + H2O2 + NaSCN in the presence and absence of porcine lung surfactant (Curosurf®) and biodegradation was monitored using UV-Vis-NIR spectroscopy, Raman spectroscopy, and scanning electron microscopy. The interaction of recombinant LPO with bundles of ox-SWCNTs was confirmed by atomic force microscopy. Cell-free biodegradation of ox-SWCNTs was also observed ex vivo in murine bronchoalveolar lavage fluid in the presence of H2O2 + NaSCN. Our study provides evidence for biodegradation of ox-SWCNTs with a lung surfactant 'bio-corona' and expands the repertoire of mammalian peroxidases capable of biodegradation of ox-SWCNTs. These findings are relevant to inhalation exposure to these materials, as LPO serves as an important component of the airway defense system.
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| 7. |
- Droulias, Sotirios A., et al.
(författare)
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Crystal perfection by strain engineering : The case of Fe/V (001)
- 2017
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 636, s. 608-614
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Tidskriftsartikel (refereegranskat)abstract
- We study the effect of bilayer thickness at fixed volume fraction on the structural quality of Fe/V (001)superlattices. We find that such artificial metallic superlattices can be manufactured with excellent crystalquality and layering up to at least 50 Å in repeat distance (K = LFe +LV). For an intended fixed ratio of theconstituents: LFe/LV= 1/7, out-of-plane coherence lengths comparable to the thicknesses of the sampleswere obtained. We evaluate the strain in- and out-of-plane of both layers as a function of the bilayer thicknessand comment on the growth using the framework of linear elasticity theory. We interpret the stabilityof the superlattice against crystal degradation due to the alternating compressive and tensile strain, yieldingclose to ideal lattice matching to the substrate.
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| 8. |
- El-Sayed, Ramy, et al.
(författare)
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Single-Walled Carbon Nanotubes Inhibit the Cytochrome P450 Enzyme, CYP3A4
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- We report a detailed computational and experimental study of the interaction of single-walled carbon nanotubes (SWCNTs) with the drug-metabolizing cytochrome P450 enzyme, CYP3A4. Dose-dependent inhibition of CYP3A4-mediated conversion of the model compound, testosterone, to its major metabolite, 6 beta-hydroxy testosterone was noted. Evidence for a direct interaction between SWCNTs and CYP3A4 was also provided. The inhibition of enzyme activity was alleviated when SWCNTs were pre-coated with bovine serum albumin. Furthermore, covalent functionalization of SWCNTs with polyethylene glycol (PEG) chains mitigated the inhibition of CYP3A4 enzymatic activity. Molecular dynamics simulations suggested that inhibition of the catalytic activity of CYP3A4 is mainly due to blocking of the exit channel for substrates/products through a complex binding mechanism. This work suggests that SWCNTs could interfere with metabolism of drugs and other xenobiotics and provides a molecular mechanism for this toxicity. Our study also suggests means to reduce this toxicity, eg., by surface modification.
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| 9. |
- Hank, Andrew M., et al.
(författare)
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Comparative Characterisation of CNS/Epoxy and BN/Epoxy Nanodielectrics using Electrical Tree PD Measurements and Atomic Force Microscopy
- 2020
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Ingår i: International Journal of Engineering Research in Africa. - 1663-3571 .- 1663-4144. ; 48, s. 24-37
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Tidskriftsartikel (refereegranskat)abstract
- This paper contributes to the body of knowledge on the efforts to develop nanodielectrics as the next generation of insulation material. The time-to-failure under electrical tree-induced degradation of 1.09-1.35 vol.% hexagonal BN/Epoxy was found to be 3 times longer than in clean epoxy. For 0.31-0.33 vol.% CNS/Epoxy the time-to-failure was 24 times longer than the clean epoxy. The electrical treeing partial discharge behaviour in the BN/Epoxy and CNS/Epoxy showed distinct time-evolution characteristics different from those in the clean epoxy. The improved electrical tree endurance in BN/Epoxy relative to the clean epoxy can be attributed to increased mechanical stiffness. The superiority of the CNS/Epoxy as a nanodielectric is notable. The effect is suggested to be due to the electron affinity properties of the carbon nanospheres at appropriate dispersion levels.
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| 10. |
- Hicks, KG, et al.
(författare)
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Protein-metabolite interactomics of carbohydrate metabolism reveal regulation of lactate dehydrogenase
- 2023
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Ingår i: Science (New York, N.Y.). - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 379:6636, s. 996-1003
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Tidskriftsartikel (refereegranskat)abstract
- Metabolic networks are interconnected and influence diverse cellular processes. The protein-metabolite interactions that mediate these networks are frequently low affinity and challenging to systematically discover. We developed mass spectrometry integrated with equilibrium dialysis for the discovery of allostery systematically (MIDAS) to identify such interactions. Analysis of 33 enzymes from human carbohydrate metabolism identified 830 protein-metabolite interactions, including known regulators, substrates, and products as well as previously unreported interactions. We functionally validated a subset of interactions, including the isoform-specific inhibition of lactate dehydrogenase by long-chain acyl–coenzyme A. Cell treatment with fatty acids caused a loss of pyruvate-lactate interconversion dependent on lactate dehydrogenase isoform expression. These protein-metabolite interactions may contribute to the dynamic, tissue-specific metabolic flexibility that enables growth and survival in an ever-changing nutrient environment.
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| 11. |
- Jafri, S. H. M., et al.
(författare)
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Identification of vibrational signatures from short chains of interlinked molecule-nanoparticle junctions obtained by inelastic electron tunnelling spectroscopy
- 2013
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 5:11, s. 4673-4677
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Tidskriftsartikel (refereegranskat)abstract
- Short chains containing a series of metal-molecule-nanoparticle nanojunctions are a nano-material system with the potential to give electrical signatures close to those from single molecule experiments while enabling us to build portable devices on a chip. Inelastic electron tunnelling spectroscopy (IETS) measurements provide one of the most characteristic electrical signals of single and few molecules. In interlinked molecule-nanoparticle (NP) chains containing typically 5-7 molecules in a chain, the spectrum is expected to be a superposition of the vibrational signatures of individual molecules. We have established a stable and reproducible molecule-AuNP multi-junction by placing a few 1,8-octanedithiol (ODT) molecules onto a versatile and portable nanoparticle-nanoelectrode platform and measured for the first time vibrational molecular signatures at complex and coupled few-molecule-NP junctions. From quantum transport calculations, we model the IETS spectra and identify vibrational modes as well as the number of molecules contributing to the electron transport in the measured spectra.
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| 13. |
- Karlsson, Fredrik, 1974-, et al.
(författare)
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Electroluminescence and photoluminescence excitation study of asymmetric coupled GaAs/AlxGa1-xAs V-groove quantum wires
- 2004
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 70:4
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Tidskriftsartikel (refereegranskat)abstract
- We have studied systems of asymmetric coupled GaAs V-groove quantum wires p-i-n diodes, in which the electrons and holes are injected into different wires. Despite the use of a 7 nm thick AlGaAs tunnel barrier, and although we demonstrate that holes tunnel more slowly than electrons, we observe a very efficient and fast tunneling between the quantum wires (QWR's). We attribute this to the achievement of a resonance between hole levels in the two QWR's. Photoluminescence excitation experiments are compared with accurate calculations of the excitonic absorption yielding a level of carrier transfer of nearly 100%. Temperature-dependent electroluminescence exhibits clear effects of tunneling up to room temperature but cannot distinguish separate electron/hole tunneling from exciton tunneling.
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| 14. |
- Karlsson, Fredrik, 1974-, et al.
(författare)
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Electrolummescence of asymmetric coupled GaAs/AlGaAs V-groove quantum wires
- 2003
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Ingår i: Institute of Physics Conference Series. - 0951-3248 .- 2154-6630. ; 174, s. 183-186
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Tidskriftsartikel (refereegranskat)abstract
- We have studied systems of asymmetric coupled GaAs V-groove quantum wires, in which the electrons and holes are injected into different wires. Our experimental results indicate efficient electron and hole tunneling, despite a 7 nm thick AlGaAs tunnel barrier. Temperature dependent electroluminescence exhibit clear effects of tunneling up to room temperature but cannot distinguish electron/hole tunneling from exciton tunneling.
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| 16. |
- Karlsson, Fredrik, 1974-, et al.
(författare)
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Strongly reduced exciton transfer between parallel quantum wires
- 2007
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 90:10, s. 101108-101108-3
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Tidskriftsartikel (refereegranskat)abstract
- Exciton transfer between two parallel GaAs V-groove quantum wires or two planar quantum wells separated by AlGaAs barriers ranging from 5.5 nm to 20 nm thickness is studied by photoluminescence and photoluminescence excitation spectroscopy. It is found that the transfer is strongly reduced between the widely spaced quantum wires as compared with quantum wells. This observation is supported by model calculations, which yield strong dimensionality dependence of the photon-exchange transfer.
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| 21. |
- Magnus, Fridrik, et al.
(författare)
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Tuneable exchange-spring stiffness in amorphous magnetic trilayer structures
- 2021
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Ingår i: Journal of Physics. - : Institute of Physics Publishing (IOPP). - 0953-8984 .- 1361-648X. ; 33:44
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the magnetic properties of amorphous Sm10Co90/Co-60(Al70Zr30)(40)/Co-85(Al70Zr30)(15) exchange-spring magnet trilayers. The magnetically soft Co-85(Al70Zr30)(15) layer is coupled to the magnetically hard Sm10Co90 layer through the weakly magnetic low-T (c) Co-60(Al70Zr30)(40) spacer layer. The strength of the coupling can be controlled with temperature and the coupling persists above the intrinsic T (c) of the spacer layer due to a long-range magnetic proximity effect. Polarized neutron reflectivity is used to examine the magnetic profile of the trilayers during magnetization reversal. A two-step switching occurs, with the switching angle of the soft layer strongly dependent on the strength of the coupling. In the strong coupling regime a magnetic state can be achieved where the soft layer magnetization is perpendicular to the hard layer whereas in the weak coupling regime the soft layer reverses fully.
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| 26. |
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| 27. |
- Wei, Yajun, et al.
(författare)
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Exponentially decaying magnetic coupling in sputtered thin film FeNi/Cu/FeCo trilayers
- 2015
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 106:4
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic coupling in trilayer films of FeNi/Cu/FeCo deposited on Si/SiO2 substrates have been studied. While the thicknesses of the FeNi and FeCo layers were kept constant at 100 angstrom, the thickness of the Cu spacer was varied from 5 to 50 angstrom. Both hysteresis loop and ferromagnetic resonance results indicate that all films are ferromagnetically coupled. Micromagnetic simulations well reproduce the ferromagnetic resonance mode positions measured by experiments, enabling the extraction of the coupling constants. Films with a thin Cu spacer are found to be strongly coupled, with an effective coupling constant of 3 erg/cm(2) for the sample with a 5 angstrom Cu spacer. The strong coupling strength is qualitatively understood within the framework of a combined effect of Ruderman-Kittel-Kasuya-Yosida and pinhole coupling, which is evidenced by transmission electron microscopy analysis. The magnetic coupling constant surprisingly decreases exponentially with increasing Cu spacer thickness, without showing an oscillatory thickness dependence. This is partially connected to the substantial interfacial roughness that washes away the oscillation. The results have implications on the design of multilayers for spintronic applications. (C) 2015 AIP Publishing LLC.
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| 29. |
- Weman, Helge, 1960-, et al.
(författare)
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High internal quantum efficiency, narrow linewidth emission InGaAs/GaAs/AlGaAs quantum wire light-emitting diode
- 2002
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 81:15, s. 2839-2841
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Tidskriftsartikel (refereegranskat)abstract
- High internal quantum efficiency (similar to60%), narrow linewidth (as narrow as 14 meV) exciton emission at room temperature has been obtained using strained InGaAs V-groove quantum wire (QWR) light-emitting diodes (LEDs). The high efficiency is achieved with the aid of selective carrier injection through self-ordered AlGaAs vertical quantum wells (VQWs), where the VQWs are separated from the InGaAs QWRs by thin GaAs spacer layers in order to reduce nonradiative recombination and inhomogeneous alloy broadening. Evidence for excitonic recombination in these LEDs up to RT is provided by measurements of the emission energy shifts at high magnetic fields.
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