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- Singh, I N, et al.
(författare)
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Dynorphin A (1-17) induces apoptosis in striatal neurons in vitro through alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate/kainate receptor-mediated cytochrome c release and caspase-3 activation.
- 2003
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Ingår i: Neuroscience. - : Elsevier BV. - 0306-4522 .- 1873-7544. ; 122:4
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Tidskriftsartikel (refereegranskat)abstract
- Dynorphin A (1-17), an endogenous opioid neuropeptide, can have pathophysiological consequences at high concentrations through actions involving glutamate receptors. Despite evidence of excitotoxicity, the basic mechanisms underlying dynorphin-induced cell death have not been explored. To address this question, we examined the role of caspase-dependent apoptotic events in mediating dynorphin A (1-17) toxicity in embryonic mouse striatal neuron cultures. In addition, the role of opioid and/or glutamate receptors were assessed pharmacologically using dizocilpine maleate (MK(+)801), a non-equilibrium N-methyl-D-aspartate (NMDA) antagonist; 6-cyano-7-nitroquinoxaline-2,3-dione, a competitive alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA)/kainate antagonist; or (-)-naloxone, a general opioid antagonist. The results show that dynorphin A (1-17) (>or=10 nM) caused concentration-dependent increases in caspase-3 activity that were accompanied by mitochondrial release of cytochrome c and the subsequent death of cultured mouse striatal neurons. Moreover, dynorphin A-induced neurotoxicity and caspase-3 activation were significantly attenuated by the cell permeable caspase inhibitor, caspase-3 inhibitor-II (z-DEVD-FMK), further suggesting an apoptotic cascade involving caspase-3. AMPA/kainate receptor blockade significantly attenuated dynorphin A-induced cytochrome c release and/or caspase-3 activity, while NMDA or opioid receptor blockade typically failed to prevent the apoptotic response. Last, dynorphin-induced caspase-3 activation was mimicked by the ampakine CX546 [1-(1,4-benzodioxan-6-ylcarbonyl)piperidine], which suggests that the activation of AMPA receptor subunits may be sufficient to mediate toxicity in striatal neurons. These findings provide novel evidence that dynorphin-induced striatal neurotoxicity is mediated by a caspase-dependent apoptotic mechanism that largely involves AMPA/kainate receptors.
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- Stepanova, K. V., et al.
(författare)
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Influence of annealing on the structure of nanoporous oxide films on the surface of titanium‒aluminum powder alloy
- 2016
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Ingår i: Journal of Surface Investigation. X-ray, Synchrotron and Neutron Techniques. - Moscow : Maik Nauka/Interperiodica. - 1027-4510. ; 10:5, s. 933-941
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Tidskriftsartikel (refereegranskat)abstract
- Oxide films obtained during anodization of Ti‒40% Al sintered powder samples in fluorine-containing electrolytes are investigated. With scanning electron microscopy and X-ray phase analysis, it is demonstrated that an X-ray amorphous nanoporous anodic oxide film is formed on the surface of the powder microparticles under optimal anodization conditions. After annealing at T = 1093 K in air and vacuum (10‒2 Pa), the oxide films are revealed to crystallize with its regular porous structure retained. The composition of the polycrystalline anodic-oxide films annealed in air is a mixture involving TiO2 (anatase and rutile) and α- and γ-Al2O3 phases and Ti2O3 and Al2TiO5 traces. The vacuum annealing process makes it possible to identify TiO2, in which anatase is the main phase, α- and γ-Al2O3, and Ti2O3 and TiO traces. However, rutile is not revealed. The presented results indicate that the application of the anodic nanostructuring of Ti‒40% Al powders is promising for the obtainment of new photocatalytic active nanomaterials. © 2016, Pleiades Publishing, Ltd.
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- Stepanova, Kristina V., et al.
(författare)
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The structure and properties of nanoporous anodic oxide films on titanium aluminide
- 2019
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Ingår i: Kondensirovannye Sredy Mezhfaznye Granitsy. - Voronezh : Voronezh State University. - 1606-867X. ; 21:1, s. 135-145
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Tidskriftsartikel (refereegranskat)abstract
- The paper presents a structural analysis of nanoporous oxide films formed by anodizing γTiAl (Ti-40 wt. %Al) samples in fluoride containing water and waterless electrolytes. Methods and methodology. Two groups of samples produced from (1) ingots and (2) sintered powder were used for anodizing. X-ray diffraction, X-ray electron spectroscopy, and scanning electron microscopy were used to analyse the structure of the films. The band gap values of anodized powder samples were estimated based on their UV-vis absorption spectra. The reaction of degradation of methyl orange under UV-vis irradiation was used to examine the photocatalytic activity of anodized TiAl powder. Results. Anodizing performed under optimal conditions in a 10 % H2SO4+0.15 % HF water electrolyte for both groups of samples results in the formation of self-organized nanoporous films of about 350 nm thickness with effective pore diameter <dp>= (70±10) nm. All the studied oxide films are heterogeneous, consist mostly of TiO2 : Al2O3 in a ratio of approximately 1:1, and have an X-ray amorphous structure. The optical band gap value of anodized powders determined by their UV absorption was Eg∌2.5 eV. It is much less than Eg of nanotubular titanium dioxide (Eg∌3.4 eV). The study also found that the concentration of methyl orange decreases under visible light irradiation in the presence of anodized TiAl powder. Conclusion. Photocatalytic activity of the developed heterogeneous films might be initiated by the visible light irradiation (λ∌480-510 nm). In other words, the new composite "TiAl powder/TiO2-Al2O3 nanoporous oxide" exhibits activity under the visible light radiation which results in the photocatalytic degradation of methyl orange. The obtained results can be successfully used for the production of new powder nanomaterials which show photocatalytic activity under visible light irradiation.
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- Storm, N., et al.
(författare)
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3D NLTE modelling of Y and Eu : Centre-to-limb variation and solar abundances
- 2024
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 683
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Tidskriftsartikel (refereegranskat)abstract
- Context: Abundances of s- and r-process elements in Sun-like stars constrain nucleosynthesis in extreme astrophysical events, such as compact binary mergers and explosions of highly magnetised rapidly rotating massive stars.Aims: We measure solar abundances of yttrium (Y) and europium (Eu) using 3D non-local thermal equilibrium (NLTE) models. We use the model to determine the abundance of Y, and also explore the model's ability to reproduce the solar centre-to-limb variation of its lines. In addition, we determine the Eu abundance using solar disc-centre and integrated flux spectra.Methods: We developed an NLTE model of Eu and updated our model of Y with collisional data from detailed quantum-mechanical calculations. We used the IAG spatially resolved high-resolution solar spectra to derive the solar abundances of Y across the solar disc and of Eu for integrated flux and at disc centre using a set of carefully selected lines and a 3D radiation-hydrodynamics model of the solar atmosphere.Results: We find 3D NLTE solar abundances of A(Y)(3D NLTE) = 2.30 ± 0.03stat ± 0.07syst dex based on observations at all angles and A(Eu) = 0.57 ± 0.01stat ± 0.06syst dex based on the integrated flux and disc-centre intensity. 3D NLTE modelling offers the most consistent abundances across the solar disc, and resolves the problem of severe systematic bias in Y and Eu abundances inherent to 1D LTE, 1D NLTE, and 3D LTE modelling.
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