| 1. |
- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Forskningsöversikt (refereegranskat)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
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| 2. |
- Glover, T.E., Ackerman, G.D., Belkacem, A., Heimann, P.A., Hussain, Z., Padmore, H.A., Ray, C., Schoenlein, R.W., Steele, W.F., Young, D.A., Lee, R.W.
(författare)
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Metal-insulator transitions in an expanding metallic fluid: particle formation kinetics.
- 2003
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Ingår i: Physical Review Letters. ; 90, s. 36102/1-4
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Tidskriftsartikel (refereegranskat)
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| 3. |
- Huang, Shih-Wen, et al.
(författare)
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Prominent role of oxygen in the multiferroicity of DyMnO3 and TbMnO3: A resonant soft x-ray scattering spectroscopy study
- 2016
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 2469-9950. ; 94:3
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Tidskriftsartikel (refereegranskat)abstract
- Oxygen is known to play an important role in the multiferroicity of rare earth manganites; however, how this role changes with rare earth elements is still not fully understood. To address this question, we have used resonant soft x-ray scattering spectroscopy to study the F-type (0,τ,0) diffraction peak from the antiferromagnetic order in DyMnO3 and TbMnO3. We focus on the measurements at O K edge of these two manganites, supplemented by the results at Mn L2 and Dy M5 edge of DyMnO3. We show that the electronic states of different elements are coupled more strongly in DyMnO3 than in TbMnO3, presumably due to the stronger lattice distortion and the tendency to develop E-type antiferromagnetism in the ferroelectric state that promote the orbital hybridization. We also show that the anomaly in the correlation length of (0,τ,0) peak in DyMnO3 signifies the exchange interaction between Mn and rare earth spins. Our findings reveal the prominent role of oxygen orbitals in the multiferroicity of rare earth manganites and the distinct energetics between them.
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| 4. |
- Huang, S. W., et al.
(författare)
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Polaronic effect in the x-ray absorption spectra of La 1-x Ca x MnO 3 manganites
- 2019
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Ingår i: Journal of Physics: Condensed Matter. - 1361-648X. ; 31:19
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Tidskriftsartikel (refereegranskat)abstract
- X-ray absorption spectroscopy (XAS) is performed to study changes in the electronic structures of colossal magnetoresistance (CMR) and charged ordered (CO) La1-x Ca x MnO3 manganites with respect to temperature. The pre-edge features in O and Mn K-edge XAS spectra, which are highly sensitive to the local distortion of MnO6 octahedral, exhibit contrasting temperature dependence between CMR and CO samples. The seemingly counter-intuitive XAS temperature dependence can be reconciled in the context of polarons. These results help identify the most relevant orbital states associated with polarons and highlight the crucial role played by polarons in understanding the electronic structures of manganites.
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| 5. |
- Huang, Shih Wen, et al.
(författare)
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Precise dd excitations and commensurate intersite Coulomb interactions in the dissimilar cuprates YBa2Cu3 O7-y and La2-xSrxCu O4
- 2023
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Ingår i: Physical Review B. - 2469-9950. ; 107:13
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Tidskriftsartikel (refereegranskat)abstract
- Using high-resolution extreme ultraviolet resonant inelastic x-ray scattering (EUVRIXS) spectroscopy at the Cu M-edge, we observed doping dependent spectral shifts of interorbital (dd) excitations of YBa2Cu3O7-y and La2-xSrxCuO4. With increasing the hole doping level from undoped to optimally doped superconducting compositions, the leading edge of dd excitations is found to shift towards lower energy loss in a roughly linear trend that is irrespective of the cuprate species. The magnitude of the energy shift can be explained by including a 0.15 eV Coulomb attraction between Cu3d(x2-y2) electrons and the doped holes on the surrounding oxygens in the atomic multiplet calculations. The consistent energy shift between distinct cuprate families suggests that this intersite Coulomb interaction energy scale is relatively material independent, and provides an important reference point for understanding charge density wave phenomena in the cuprate phase diagram.
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| 6. |
- Huang, Shih-Wen, et al.
(författare)
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Selective interlayer ferromagnetic coupling between the Cu spins in YBa2Cu3O7-x grown on top of La0.7Ca0.3MnO3.
- 2015
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Studies to date on ferromagnet/d-wave superconductor heterostructures focus mainly on the effects at or near the interfaces while the response of bulk properties to heterostructuring is overlooked. Here we use resonant soft x-ray scattering spectroscopy to reveal a novel c-axis ferromagnetic coupling between the in-plane Cu spins in YBa2Cu3O7-x (YBCO) superconductor when it is grown on top of ferromagnetic La0.7Ca0.3MnO3 (LCMO) manganite layer. This coupling, present in both normal and superconducting states of YBCO, is sensitive to the interfacial termination such that it is only observed in bilayers with MnO2 but not with La0.7Ca0.3O interfacial termination. Such contrasting behaviors, we propose, are due to distinct energetic of CuO chain and CuO2 plane at the La0.7Ca0.3O and MnO2 terminated interfaces respectively, therefore influencing the transfer of spin-polarized electrons from manganite to cuprate differently. Our findings suggest that the superconducting/ferromagnetic bilayers with proper interfacial engineering can be good candidates for searching the theorized Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) state in cuprates and studying the competing quantum orders in highly correlated electron systems.
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| 7. |
- Lee, Jenn-Min, et al.
(författare)
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The magnetic order in multiferroic DyMnO3
- 2021
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048. ; 246
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Tidskriftsartikel (refereegranskat)abstract
- With flexibility in tuning their electric and magnetic properties, multiferroics can be used in information exchange and storage in ways that are very different from the present electronic materials. Here we use resonant soft x-ray scattering spectroscopy to study the -type and -type (0, 1-, 0) diffraction peaks from sinusoidal antiferromagnetic spin order in multiferroic DyMnO. By comparing the temperature dependence of ordering wave vectors , peak intensities , and correlation lengths measured at Mn -, O -, and Dy -edges, we show that the nearly perfect locking between the ordering wave vectors from Dy states and Mn 3 orbitals manifesting the second harmonic diffraction peak implies the notable orbital involvement in the coupling between Mn and Dy spins. Our DFT calculations further suggest that the lattice response to different antiferromagnetic ground states (A-type versus E-type) is much weaker in TbMnO, in agreement with previous claim that the symmetric exchange interaction can be an important factor for understanding the ferroelectricity in DyMnO than in TbMnO.
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