| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- 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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| 3. |
- 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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| 4. |
- Hsu, Ya-Ching, et al.
(författare)
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Methadone concentrations in blood, plasma, and oral fluid determined by isotope-dilution gas chromatography-mass spectrometry
- 2013
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Ingår i: Analytical and Bioanalytical Chemistry. - : Springer Verlag (Germany). - 1618-2642 .- 1618-2650. ; 405:12, s. 3921-3928
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Tidskriftsartikel (refereegranskat)abstract
- Methadone (MTD) is widely used for detoxification of heroin addicts and also in pain management programs. Information about the distribution of methadone between blood, plasma, and alternative specimens, such as oral fluid (OF), is needed in clinical, forensic, and traffic medicine when analytical results are interpreted. We determined MTD and its metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in blood, plasma, blood cells, and OF by gas chromatography-mass spectrometry (GC-MS) after adding deuterium-labeled internal standards. The analytical limits of quantitation for MTD and EDDP by this method were 20 and 3 ng/mL, respectively. The amounts of MTD and EDDP were higher in plasma (80.4 % and 76.5 %) compared with blood cells (19.6 % and 23.5 %) and we found that repeated washing of blood cells with phosphate-buffered saline increased the amounts in plasma (93.6 % and 88.6 %). Mean plasma/blood concentration ratios of MTD and EDDP in spiked samples (N = 5) were 1.27 and 1.21, respectively. In clinical samples from patients (N = 46), the concentrations of MTD in plasma and whole blood were highly correlated (r = 0.92, p andlt; 0.001) and mean (median) plasma/blood distribution ratios were 1.43 (1.41). The correlations between MTD in OF and plasma (r = 0.46) and OF and blood (r = 0.52) were also statistically significant (p andlt; 0.001) and the mean OF/plasma and OF/blood distribution ratios were 0.55 and 0.77, respectively. The MTD concentration in OF decreased as salivary pH increased (more basic). These results will prove useful in clinical and forensic medicine when MTD concentrations in alternative specimens are compared and contrasted.
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| 5. |
- Lin, Shao-Hua, et al.
(författare)
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Study on different isolation technology on the performance of blue micro-LEDs array applications
- 2024
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Ingår i: DISCOVER NANO. - : SPRINGER. - 2731-9229. ; 19:1
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a 3 x 3 blue micro-LED array with a pixel size of 10 x 10 mu m2 and a pitch of 15 mu m was fabricated on an epilayer grown on a sapphire substrate using metalorganic chemical vapor deposition technology. The fabrication process involved photolithography, wet and dry etching, E-beam evaporation, and ion implantation technology. Arsenic multi-energy implantation was utilized to replace the mesa etching for electrical isolation, where the implantation depth increased with the average energy. Different ion depth profiles had varying effects on electrical properties, such as forward current and leakage currents, potentially causing damage to the n-GaN layer and increasing the series resistance of the LEDs. As the implantation depth increased, the light output power and peak external quantum efficiency of the LEDs also increased, improving from 5.33 to 9.82%. However, the efficiency droop also increased from 46.3 to 48.6%.
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| 6. |
- Wu, Han-Chun, et al.
(författare)
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Transport Gap Opening and High On-Off Current Ratio in Trilayer Graphene with Self-Aligned Nanodomain Boundaries.
- 2015
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 9:9, s. 8967-8975
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Tidskriftsartikel (refereegranskat)abstract
- Trilayer graphene exhibits exceptional electronic properties that are of interest both for fundamental science and for technological applications. The ability to achieve a high on-off current ratio is the central question in this field. Here, we propose a simple method to achieve a current on-off ratio of 10(4) by opening a transport gap in Bernal-stacked trilayer graphene. We synthesized Bernal-stacked trilayer graphene with self-aligned periodic nanodomain boundaries (NBs) on the technologically relevant vicinal cubic-SiC(001) substrate and performed electrical measurements. Our low-temperature transport measurements clearly demonstrate that the self-aligned periodic NBs can induce a charge transport gap greater than 1.3 eV. More remarkably, the transport gap of ∼0.4 eV persists even at 100 K. Our results show the feasibility of creating new electronic nanostructures with high on-off current ratios using graphene on cubic-SiC.
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| 7. |
- Ademuyiwa, Adesoji O., et al.
(författare)
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Determinants of morbidity and mortality following emergency abdominal surgery in children in low-income and middle-income countries
- 2016
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Ingår i: BMJ Global Health. - : BMJ Publishing Group Ltd. - 2059-7908. ; 1:4
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Tidskriftsartikel (refereegranskat)abstract
- Background: Child health is a key priority on the global health agenda, yet the provision of essential and emergency surgery in children is patchy in resource-poor regions. This study was aimed to determine the mortality risk for emergency abdominal paediatric surgery in low-income countries globally.Methods: Multicentre, international, prospective, cohort study. Self-selected surgical units performing emergency abdominal surgery submitted prespecified data for consecutive children aged <16 years during a 2-week period between July and December 2014. The United Nation's Human Development Index (HDI) was used to stratify countries. The main outcome measure was 30-day postoperative mortality, analysed by multilevel logistic regression.Results: This study included 1409 patients from 253 centres in 43 countries; 282 children were under 2 years of age. Among them, 265 (18.8%) were from low-HDI, 450 (31.9%) from middle-HDI and 694 (49.3%) from high-HDI countries. The most common operations performed were appendectomy, small bowel resection, pyloromyotomy and correction of intussusception. After adjustment for patient and hospital risk factors, child mortality at 30 days was significantly higher in low-HDI (adjusted OR 7.14 (95% CI 2.52 to 20.23), p<0.001) and middle-HDI (4.42 (1.44 to 13.56), p=0.009) countries compared with high-HDI countries, translating to 40 excess deaths per 1000 procedures performed.Conclusions: Adjusted mortality in children following emergency abdominal surgery may be as high as 7 times greater in low-HDI and middle-HDI countries compared with high-HDI countries. Effective provision of emergency essential surgery should be a key priority for global child health agendas.
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| 8. |
- Bairagi, Samiran, et al.
(författare)
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Formation of quaternary Zn(AlxGa1−x)2O4 epilayers driven by thermally induced interdiffusion between spinel ZnGa2O4 epilayer and Al2O3 substrate
- 2023
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Ingår i: Materials Today Advances. - : Elsevier. - 2590-0498. ; 20
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Tidskriftsartikel (refereegranskat)abstract
- Zinc aluminogallate, Zn(AlxGa1−x)2O4 (ZAGO), a single-phase spinel structure, offers considerable potential for high-performance electronic devices due to its expansive compositional miscibility range between aluminum (Al) and gallium (Ga). Direct growth of high-quality ZAGO epilayers however remains problematic due to the high volatility of zinc (Zn). This work highlights a novel synthesis process for high-quality epitaxial quaternary ZAGO thin films on sapphire substrates, achieved through thermal annealing of a ZnGa2O4 (ZGO) epilayer on sapphire in an ambient air setting. In-situ annealing x-ray diffraction measurements show that the incorporation of Al in the ZGO epilayer commenced at 850 °C. The Al content (x) in ZAGO epilayer gradually increased up to around 0.45 as the annealing temperature was raised to 1100 °C, which was confirmed by transmission electron microscopy (TEM) and energy dispersive x-ray spectroscopy. X-ray rocking curve measurement revealed a small full width at half maximum value of 0.72 °, indicating the crystal quality preservation of the ZAGO epilayer with a high Al content. However, an epitaxial intermediate �–(AlxGa1−x)2O3 layer (� - AGO) was formed between the ZAGO and sapphire substrate. This is believed to be a consequence of the interdiffusion of Al and Ga between the ZGO thin film and sapphire substrate. Using density functional theory, the substitution cost of Ga in sapphire was determined to be about 0.5 eV lower than substitution cost of Al in ZGO. Motivated by this energetically favorable substitution, a formation mechanism of the ZAGO and AGO layers was proposed. Spectroscopic ellipsometry studies revealed an increase in total thickness of the film from 105.07 nm (ZGO) to 147.97 nm (ZAGO/AGO) after annealing to 1100 °C, which were corroborated using TEM. Furthermore, an observed increase in the direct (indirect) optical bandgap from 5.06 eV (4.7 eV) to 5.72 eV (5.45 eV) with an increasing Al content in the ZAGO layer further underpins the formation of a quaternary ZAGO alloy with a tunable composition.
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| 9. |
- Damy, Thibaud, et al.
(författare)
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Transthyretin cardiac amyloidosis in continental Western Europe : An insight through the Transthyretin Amyloidosis Outcomes Survey (THAOS)
- 2019
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Ingår i: European Heart Journal. - : Oxford University Press. - 0195-668X .- 1522-9645. ; 43:5, s. 391-400
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Tidskriftsartikel (refereegranskat)abstract
- Aims: Transthyretin amyloidosis (ATTR amyloidosis) is a heterogeneous disorder with cardiac, neurologic, and mixed phenotypes. We describe the phenotypic and genotypic profiles of this disease in continental Western Europe as it appears from the Transthyretin Amyloidosis Survey (THAOS).Methods and results: THAOS is an ongoing, worldwide, longitudinal, observational survey established to study differences in presentation, diagnosis, and natural history in ATTR amyloidosis subjects. At data cut-off, 1411 symptomatic subjects from nine continental Western European countries were enrolled in THAOS [1286 hereditary (ATTRm) amyloidosis; 125 wild-type ATTR (ATTRwt) amyloidosis]. Genotypes and phenotypes varied notably by country. Four mutations (Val122Ile, Leu111Met, Thr60Ala, and Ile68Leu), and ATTRwt, were associated with a mainly cardiac phenotype showing symmetric left ventricular (LV) hypertrophy, normal diastolic LV dimensions and volume, and mildly depressed LV ejection fraction (LVEF). Morphologic and functional abnormalities on echocardiogram were significantly more severe in subjects with cardiac (n = 210), compared with a mixed (n = 298), phenotype: higher median (Q1-Q3) interventricular septal thickness [18 (16-21) vs. 16 (13-20) mm; P = 0.0006]; and more frequent incidence of LVEF <50% (38.1 vs. 17.5%; P = 0.0008). Subjects with cardiac mutations or ATTRwt (or cardiac or mixed phenotype) had a lower survival rate than subjects in other genotype (or the neurologic phenotype) categories (P < 0.0001, for both).Conclusion: ATTR amyloidosis genotypes and phenotypes are highly heterogeneous in continental Western Europe. A geographic map of the different disease profiles and awareness that a subset of subjects have a dominant cardiac phenotype, mimicking hypertrophic cardiomyopathy, at presentation can facilitate the clinical recognition of this underdiagnosed disease.Trial registration: ClinicalTrials.gov: NCT00628745.
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| 10. |
- 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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| 11. |
- 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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| 12. |
- Wu, Han-Chun, et al.
(författare)
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Large positive in-plane magnetoresistance induced by localized states at nanodomain boundaries in graphene
- 2017
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Graphene supports long spin lifetimes and long diffusion lengths at room temperature, making it highly promising for spintronics. However, making graphene magnetic remains a principal challenge despite the many proposed solutions. Among these, graphene with zig-zag edges and ripples are the most promising candidates, as zig-zag edges are predicted to host spin-polarized electronic states, and spin-orbit coupling can be induced by ripples. Here we investigate the magnetoresistance of graphene grown on technologically relevant SiC/Si(001) wafers, where inherent nanodomain boundaries sandwich zig-zag structures between adjacent ripples of large curvature. Localized states at the nanodomain boundaries result in an unprecedented positive in-plane magnetoresistance with a strong temperature dependence. Our work may offer a tantalizing way to add the spin degree of freedom to graphene.
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