| 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. |
- Xu, Guangwei, et al.
(författare)
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Synthesis, properties, and top-gated metal-oxide-semiconductor field-effect transistors of p-type GaSb nanowires
- 2013
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 3:43, s. 19834-19839
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Tidskriftsartikel (refereegranskat)abstract
- High-quality GaSb nanowires (NWs) have been synthesized via chemical vapor deposition. The as-synthesized NWs have a zinc-blende structure with growth direction along a < 011 > direction. Raman spectrum of the GaSb NWs consists of two peaks, corresponding to the LO and TO phonon modes, respectively. The temperature dependence of the photoluminescence spectra shows a blue-shift as the temperature decreases from 300 to 13 K. The electrical properties of the GaSb NWs are investigated over a wide range of temperatures from 25 mK to 291 K. The results show that the GaSb NWs exhibit excellent p-type transistor performance at low temperatures (<40 K). The room-temperature hole density and mobility were found to be similar to 2.2 x 10(18) cm(-3) and similar to 14.2 cm(2) V-1 s(-1), respectively. The Schottky contact characteristics were observed and the barrier height was found to be similar to 14 meV. Our results show that the GaSb NWs could be used as building blocks for emerging p-type nanoelectronic devices in extremely low temperature environments.
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| 3. |
- Ranjan, Alok, 1992, et al.
(författare)
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Probing resistive switching in HfO 2 /Al 2 O 3 bilayer oxides using in-situ transmission electron microscopy
- 2023
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Ingår i: Applied Materials Today. - : Elsevier BV. - 2352-9407. ; 31
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we investigate the resistive switching in hafnium dioxide (HfO2) and aluminum oxide (Al2O3) bilayered stacks using in-situ transmission electron microscopy and X-ray energy dispersive spectroscopy. Conductance of the HfO2/Al2O3 stack changes gradually upon electrical stressing which is related to the formation of extended nanoscale physical defects at the HfO2/Al2O3 interface and the migration and re-crystallization of Al into the oxide bulk. The results suggest two competing physical mechanisms including the redistribution of oxygen ions and the migration of Al species from the Al electrode during the switching process. While the HfO2/Al2O3 bilayered stack appears to be a good candidate for RRAM technology, the low diffusion barrier of the active Al electrode causes severe Al migration in the bi-layered oxides leading to the device to fail in resetting, and thereby, largely limiting the overall switching performance and material reliability.
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| 4. |
- Xie, Zi Kang, et al.
(författare)
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Electron scale coherent structure as micro accelerator in the Earth's magnetosheath
- 2024
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 15:1, s. 886-
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Tidskriftsartikel (refereegranskat)abstract
- Turbulent energy dissipation is a fundamental process in plasma physics that has not been settled. It is generally believed that the turbulent energy is dissipated at electron scales leading to electron energization in magnetized plasmas. Here, we propose a micro accelerator which could transform electrons from isotropic distribution to trapped, and then to stream (Strahl) distribution. From the MMS observations of an electron-scale coherent structure in the dayside magnetosheath, we identify an electron flux enhancement region in this structure collocated with an increase of magnetic field strength, which is also closely associated with a non-zero parallel electric field. We propose a trapping model considering a field-aligned electric potential together with the mirror force. The results are consistent with the observed electron fluxes from ~50 eV to ~200 eV. It further demonstrates that bidirectional electron jets can be formed by the hourglass-like magnetic configuration of the structure.
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| 5. |
- Xu, Shuang Feng, et al.
(författare)
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Lactoferrin ameliorates dopaminergic neurodegeneration and motor deficits in MPTP-treated mice
- 2019
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Ingår i: Redox Biology. - : Elsevier BV. - 2213-2317. ; 21
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Tidskriftsartikel (refereegranskat)abstract
- Brain iron accumulation is common in patients with Parkinson's disease (PD). Iron chelators have been investigated for their ability to prevent neurodegenerative diseases with features of iron overload. Given the non-trivial side effects of classical iron chelators, lactoferrin (Lf), a multifunctional iron-binding globular glycoprotein, was screened to identify novel neuroprotective pathways against dopaminergic neuronal impairment. We found that Lf substantially ameliorated PD-like motor dysfunction in the subacute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of PD. We further showed that Lf could alleviate MPTP-triggered apoptosis of DA neurons, neuroinflammation, and histological alterations. As expected, we also found that Lf suppressed MPTP-induced excessive iron accumulation and the upregulation of divalent metal transporter (DMT1) and transferrin receptor (TFR), which is the main intracellular iron regulation protein, and subsequently improved the activity of several antioxidant enzymes. We probed further and determined that the neuroprotection provided by Lf was involved in the upregulated levels of brain-derived neurotrophic factor (BDNF), hypoxia-inducible factor 1α (HIF-1α) and its downstream protein, accompanied by the activation of extracellular regulated protein kinases (ERK) and cAMP response element binding protein (CREB), as well as decreased phosphorylation of c-Jun N-terminal kinase (JNK) and mitogen activated protein kinase (MAPK)/P38 kinase in vitro and in vivo. Our findings suggest that Lf may be an alternative safe drug in ameliorating MPTP-induced brain abnormalities and movement disorder.
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| 6. |
- Zhang, Hui-ning, et al.
(författare)
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Carbothermic Reduction of Zinc and Iron Oxides in Electric Arc Furnace Dust
- 2014
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Ingår i: Journal of Iron and Steel Research International. - 1006-706X .- 2210-3988. ; 21:4, s. 427-432
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Tidskriftsartikel (refereegranskat)abstract
- The reduction of zinc and iron oxides from electric arc furnace dust (EAFD) by carbon was investigated at temperatures between 800 and 1300 °C. The analytic technique employed includes chemical analysis, X-ray fluorescence spectroscopy (XRF), X-ray powder diffraction (XRD), scanning electron microscopy (SEM) equipped with X-ray energy dispersive spectrometry (EDS), and thermodynamic database FactSage 6. 2. It was found that the reduction of zinc and iron oxides depends largely on Boudouad reaction. At 900 °C, zinc exists in tested samples as ZnO, which is reduced in the temperature range of 1000 — 1100 °C. At 1100 °C, 99. 11% of the zinc is evaporated. The metallization ratio of Fe is 79. 19% at 1300 °C, as the content of Fe2+ is still 9. 40%. A higher temperature is thus required for a higher reduction degree of Fe oxides by solid or gaseous carbon
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| 7. |
- Zhang, Wei, et al.
(författare)
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Activation of nuclear factor-kappa B pathway is responsible for tumor necrosis factor-a-induced up-regulation of endothelin B2 receptor expression in vascular smooth muscle cells in vitro
- 2012
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Ingår i: Toxicology Letters. - : Elsevier BV. - 1879-3169 .- 0378-4274. ; 209:2, s. 107-112
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Tidskriftsartikel (refereegranskat)abstract
- The endothelin B2 (ETB2) receptors are induced in vascular smooth muscle cells (VSMCs) in cardiovascular diseases. We tested if in vitro short-term exposure to the pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) could up-regulate ETB2 receptors in rat mesenteric arteries, and if this effect is through activation of intracellular nuclear factor-kappa B (NF-kappa B) pathway. The mesenteric arteries were dissected from male Sprague-Dawley rats and the endothelium was removed. The arteries were co-incubated with TNF-alpha in serum-free Dulbecco's modified Eagle's medium. Real-time reverse transcription-PCR, Western blot and immunohistochemical staining were employed to assess the mRNA/protein expression of ETB2 receptors and activation of NF-kappa B pathway. The results showed that, during organ culture. TNF-alpha concentration-dependently enhanced ET52 receptors expression at both mRNA and protein levels, paralleled with activation of NF-kappa B pathway in VSMC. The up-regulated ETB2 receptor expression and NF-kappa B activation could be effectively suppressed by general transcriptional inhibitor actinomycin D, or either of the selective I kappa B kinase inhibitors wedelolactone and IMD-0354. Conclusively, the activation of intracellular NF-kappa B pathway is responsible for the up-regulation of ETB2 receptors induced by short-term exposure to TNF-alpha. This could partly explain the toxic effects of TNF-alpha on VSMCs that account for cardiovascular diseases. (C) 2011 Elsevier Ireland Ltd. All rights reserved.
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