| 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. |
- Serban, Alexandra, et al.
(författare)
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Selective-area growth of single-crystal wurtzite GaN nanorods on SiOx/Si(001) substrates by reactive magnetron sputter epitaxy exhibiting single-mode lasing
- 2017
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Selective-area growth (SAG) of single-crystal wurtzite GaN nanorods (NRs) directly onto Si(001) substrates with un-etched native SiOx amorphous layer, assisted by a patterning TiNx mask fabricated by nanosphere lithography (NSL), has been realized by reactive magnetron sputter epitaxy (MSE). The GaN NRs were grown vertically to the substrate surface with the growth direction along c-axis in the well-defined nano-opening areas. A 5-step structural and morphological evolution of the SAG NRs observed at different sputtering times depicts a comprehensive growth model, listed in sequence as: formation of a polycrystalline wetting layer, predominating c-axis oriented nucleation, coarsening and coalescence of multi-islands, single NR evolution, and finally quasi-equilibrium crystal shape formation. Room-temperature cathodoluminescence spectroscopy shows a strong GaN bandedge emission with a uniform luminescence across the NRs, indicating that the SAG NRs are grown with high quality and purity. In addition, single-longitudinal-mode lasing, attributed to well-faceted NR geometry forming a Fabry-Perot cavity, was achieved by optical pumping, paving a way for fabricating high-performance laser optoelectronics using MSE.
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| 3. |
- Huang, Chih-Yang, et al.
(författare)
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Heteroepitaxially grown homojunction gallium oxide PN diodes using ion implantation technologies
- 2024
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Ingår i: Materials Today Advances. - : ELSEVIER. - 2590-0498. ; 22
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Tidskriftsartikel (refereegranskat)abstract
- Although advancements in n- and p-doping of gallium oxide (Ga2O3) are underway, the realization of functional pn diodes remains elusive. Here, we present the successful fabrication of a Ga2O3 pn diode utilizing ion implantation technology. The Ga2O3 epilayers were grown on c-plane sapphire substrates by metalorganic chemical vapor deposition (MOCVD). P-type conductivity Ga2O3 epilayer, confirmed by Hall effect analysis, was achieved by phosphorus (P) ion implantation followed with a rapid thermal annealing (RTA) process. This p-Ga2O3 epilayer reveals a significant reduction in resistivity (<10(6)) compared to undoped Ga2O3, demonstrating the successful inclusion and activation of P within the crystal lattice. X-ray diffraction analysis shows that the Ga2O3 epilayers were grown in high crystal quality. Although the crystallinity of Ga2O3 was slightly degraded after P ion implantation, the structure was recovered to high-quality crystal after RTA treatment. For the device structure, p-type Ga2O3 was formed first, followed n-type Ga2O3 regrowth to create a pn junction diode. The obtained results demonstrate a built-in voltage of 4.8 V, 4.2 V, and 4.308 V from simulation, fabricated pn diodes measured by I-V and C-V, respectively. A high breakdown voltage of 900 V was also obtained for the lateral pn diode grown on sapphire substrate. As concerning temperature stability, I-V curves of Ga2O3 pn diode were measured from 25 degrees C to 150 degrees C in steps of 25 degrees C. At elevated temperatures, for both forward and reverse biases, consecutive increasing currents were measured. These could be resulted from dominant diffusion and drift currents over recombination current at a given bias. In addition, the reverse current saturated (@V > 3kT/q) and remained very low at 2x10(-8) A, as the diode operated at 150 degrees C. The behavior could be due to Ga2O3 being a wide bandgap material.
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| 4. |
- Lu, Chan-Hung, et al.
(författare)
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beta-Ga2O3 MOSFETs electrical characteristic study of various etching depths grown on sapphire substrate by MOCVD
- 2023
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Ingår i: DISCOVER NANO. - : SPRINGER. - 2731-9229. ; 18:1
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Tidskriftsartikel (refereegranskat)abstract
- beta-Ga2O3 thin films with both a 45 nm Si-doped conductive epilayer and unintentionally doped epilayer were grown on c-plane sapphire substrate by metalorganic chemical vapor deposition. beta-Ga2O3 based metal-oxide-semiconductor field-effect transistors (MOSFETs) were fabricated with gate recess depths of 20 nm and 40 nm (it indicated gate depth with 70 nm and 50 nm, respective), respectively, and without said recessing process. The conductivity of beta-Ga2O3 epilayers was improved through low in situ doping using a tetraethoxysilane precursor to increase MOSFET forward current density. After recessing, MOSFET operation was transferred from depletion to enhanced mode. In this study, the maximum breakdown voltage of the recessed 40 nm transistor was 770 V. The etching depth of a recessed-gate device demonstrates its influence on device electrical performance.
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