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- 2019
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Tidskriftsartikel (refereegranskat)
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- 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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| 5. |
- Horng, Ray-Hua, et al.
(författare)
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Growth and Characterization of Sputtered InAlN Nanorods on Sapphire Substrates for Acetone Gas Sensing
- 2024
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Ingår i: Nanomaterials. - : MDPI. - 2079-4991. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- The demand for highly sensitive and selective gas sensors has been steadily increasing, driven by applications in various fields such as environmental monitoring, healthcare, and industrial safety. In this context, ternary alloy indium aluminum nitride (InAlN) semiconductors have emerged as a promising material for gas sensing due to their unique properties and tunable material characteristics. This work focuses on the fabrication and characterization of InAlN nanorods grown on sapphire substrates using an ultra-high vacuum magnetron sputter epitaxy with precise control over indium composition and explores their potential for acetone-gas-sensing applications. Various characterization techniques, including XRD, SEM, and TEM, demonstrate the structural and morphological insights of InAlN nanorods, making them suitable for gas-sensing applications. To evaluate the gas-sensing performance of the InAlN nanorods, acetone was chosen as a target analyte due to its relevance in medical diagnostics and industrial processes. The results reveal that the InAlN nanorods exhibit a remarkable sensor response of 2.33% at 600 ppm acetone gas concentration at an operating temperature of 350 degrees C, with a rapid response time of 18 s. Their high sensor response and rapid response make InAlN a viable candidate for use in medical diagnostics, industrial safety, and environmental monitoring.
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| 6. |
- Horng, Ray-Hua, et al.
(författare)
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Structure Effect on the Response of ZnGa2O4 Gas Sensor for Nitric Oxide Applications
- 2022
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Ingår i: Nanomaterials. - : MDPI. - 2079-4991. ; 12:21
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Tidskriftsartikel (refereegranskat)abstract
- We fabricated a gas sensor with a wide-bandgap ZnGa2O4 (ZGO) epilayer grown on a sapphire substrate by metalorganic chemical vapor deposition. The ZGO presented (111), (222) and (333) phases demonstrated by an X-ray diffraction system. The related material characteristics were also measured by scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. This ZGO gas sensor was used to detect nitric oxide (NO) in the parts-per-billion range. In this study, the structure effect on the response of the NO gas sensor was studied by altering the sensor dimensions. Two approaches were adopted to prove the dimension effect on the sensing mechanism. In the first approach, the sensing area of the sensors was kept constant while both channel length (L) and width (W) were varied with designed dimensions (L x W) of 60 x 200, 80 x 150, and 120 x100 mu m(2). In the second, the dimensions of the sensing area were altered (60, 40, and 20 mu m) with W kept constant. The performance of the sensors was studied with varying gas concentrations in the range of 500 ppb similar to 10 ppm. The sensor with dimensions of 20 x 200 mu m(2) exhibited a high response of 11.647 in 10 ppm, and 1.05 in 10 ppb for NO gas. The sensor with a longer width and shorter channel length exhibited the best response. The sensing mechanism was provided to explain the above phenomena. Furthermore, the reaction between NO and the sensor surface was simulated by O exposure of the ZGO surface in air and calculated by first principles.
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| 8. |
- Horng, Ray-Hua, et al.
(författare)
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Growth mechanism and characteristics of beta-Ga2O3 heteroepitaxailly grown on sapphire by metalorganic chemical vapor deposition
- 2022
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Ingår i: Materials Today Advances. - : ELSEVIER. - 2590-0498. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- In this study, monoclinic gallium oxide (beta-Ga2O3) epilayer was successfully grown on c-plane, (0001), sapphire substrate by metalorganic chemical vapor deposition (MOCVD) with interplaying growth temperature, TEGa flow rate, and growth time. X-ray diffraction 20 scans show only three narrow diffraction peaks referred to beta-Ga2O3 ((2) over bar 01), ((4) over bar 02), and ((6) over bar 03) in all epilayers, indicating a superior crystalline quality. Current-voltage (I-V) measurement reveals that these beta-Ga2O3 films are insulating and exhibit high resistance in a range of 10(12)-10(14) Omega. The crystallization characteristics of the epilayers can be effectively improved with thickness through increasing TEGa flow rate and growth time, which was evidenced by X-ray rocking curves and I-V measurements. However, the surface roughness of beta-Ga2O3 film increases with growth time and TEGa flow rate. When the growth temperature increases above 825 degrees C, the thickness of beta-Ga2O3 film decreases clearly. Furthermore, it can be found that the growth rate decreased as the growth time increasing. The growth mechanism based on first-principles calculation was proposed as that 3D growth induced by the lattice mismatch between beta-Ga2O3 and sapphire starts at nucleation stage, and follows up a lateral growth promoting a 2D growth after the thick epilayer being grown. In addition, the complex chemical reaction between TEGa and oxygen precursors was unraveled by density function theory calculation. (c) 2022 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).
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| 9. |
- Hsu, Yu-Hsuan, et al.
(författare)
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epsilon-Ga2O3 Grown on c-Plane Sapphire by MOCVD with a Multistep Growth Process
- 2022
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Ingår i: Crystal Growth & Design. - : AMER CHEMICAL SOC. - 1528-7483 .- 1528-7505. ; 22:3
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Tidskriftsartikel (refereegranskat)abstract
- Gallium oxide (Ga2O3) has especially become popular because of its established applications in semiconductors. Of five polymorphs, monoclinic beta-Ga2O3 is the most thermodynamically stable phase. However, orthorhombic Ga2O3 (also known as epsilon-Ga2O3 or kappa-Ga2O3) is gaining increasing interest due to its high lattice symmetry and peculiar ferroelectricity. Although the structural approach for estimating Ga2O3 has been studied both theoretically and experimentally, epsilon-Ga2O3 and kappa-Ga2O3 are still confused. In this study, epsilon-Ga2O3 epilayers are grown on c-plane sapphire by metal-organic chemical vapor deposition with a multistep growth process. A thin annealed epsilon-Ga2O3 buffer layer is grown in the first step. The sequent growth steps with slow, fast, or combination of slow then fast growth rate significantly influence the quality of epilayers compared with that of directly grown Ga2O3. Through a detailed transmission electron microscopy (TEM) characterization of these Ga2O3 epilayers, the structural relationship between orthorhombic kappa-Ga2O3 and hexagonal epsilon-Ga2O3 is elucidated. A series of first-principles density functional theory calculations are also carried out to confirm the argument.
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