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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. |
- 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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| 4. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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| 5. |
- Liu, Peng, et al.
(författare)
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Novel and Stable D-A-π-A Dyes for Efficient Solid-state Dye-sensitized Solar Cells
- 2017
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 2:5, s. 1812-1819
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Tidskriftsartikel (refereegranskat)abstract
- Two novel organic donor–acceptor−π–acceptor sensitizers, W7 and W8, have been applied in efficient solid-state dye-sensitized solar cells (ssDSSCs). Using 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenyl-amine) 9,9′-spirobifluorene (Spiro-OMeTAD) as hole-transport material (HTM), an excellent power conversion efficiency of 6.9% was recorded for W7, together with an excellent photocurrent of 10.51 mA cm–2 and a high open-circuit voltage of 880 mV under standard AM 1.5 G illumination (100 mW cm–2). The solid-state solar cells based on W8 showed an efficiency of 5.2%, with a good photocurrent of 9.55 mA cm–2 and an open-circuit voltage of 870 mV. Compared to that of the well-known WS2 sensitizer, the results show that the performance of the ssDSSC devices can be significantly improved by introducing triphenylamine moiety into their structure. In addition, results of photoinduced absorption spectroscopy show efficient dye regeneration for W7- and W8-based devices. A higher hole conductivity of the W7/HTM and W8/HTM layers compared to that of the WS2/HTM layer was observed, indicating an efficient charge transfer at the interfaces. The results obtained offer insights into the design of reliable and highly efficient ssDSSCs for large-scale applications.
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| 6. |
- Fang, Shuhong, et al.
(författare)
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Environment occurrence of perfluoroalkyl acids and associated human health risks near a major fluorochemical manufacturing park in southwest of China
- 2020
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Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 0304-3894 .- 1873-3336. ; 396
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Tidskriftsartikel (refereegranskat)abstract
- Despite China being the largest global manufacturer of perfluoroalkyl acids (PFAAs), few studies have been carried out on the environmental occurrence and associated human health risks of PFAAs emitted from manufacturing sites in China. Here, river water, tap water, soil and leaf samples were collected around a major fluorochemical manufacturing park (FMP) in the southwest of China in 2019. High EPFAA concentrations (sum of 12 PFAAs) of 3817 ng/L, 3254 ng/L, 322 - 476 ng/g dw and 23401-33749 ng/g dw were measured near the FMP in river water, tap water, soil and leaves, respectively, indicating that the FMP is a point source of PFAAs. PFOA was the predominant PFAA in all samples (58.5-98.6 %) indicating the production or use of PFOA at the FMP. PFOA concentrations in most tap water samples (> 300 ng/L in 31 of 38 samples) exceeded the U.S. EPA health advisory. Proportions of branched PFOA isomers in all samples were in 5.9-47.4 %, suggesting the production or use of PFOA manufactured by electrochemical fluorination at the FMP. It is recommended to focus more attention on branched PFOA isomers in the future because otherwise health risks may be underestimated due to their relatively high proportions in China.
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| 7. |
- Chu, Ming, et al.
(författare)
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Accurate capacitance-voltage characterization of organic thin films with current injection*
- 2021
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Ingår i: Chinese Physics B. - : IOP PUBLISHING LTD. - 1674-1056. ; 30:8
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Tidskriftsartikel (refereegranskat)abstract
- To deal with the invalidation of commonly employed series model and parallel model in capacitance-voltage (C-V) characterization of organic thin films when current injection is significant, a three-element equivalent circuit model is proposed. On this basis, the expression of real capacitance in consideration of current injection is theoretically derived by small-signal analysis method. The validity of the proposed equivalent circuit and theoretical expression are verified by a simulating circuit consisting of a capacitor, a diode, and a resistor. Moreover, the accurate C-V characteristic of an organic thin film device is obtained via theoretical correction of the experimental measuring result, and the real capacitance is 35.7% higher than the directly measured capacitance at 5-V bias in the parallel mode. This work strongly demonstrates the necessity to consider current injection in C-V measurement and provides a strategy for accurate C-V characterization experimentally.
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| 8. |
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| 9. |
- Yuan, Bo, et al.
(författare)
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Long-Chain Chlorinated Paraffins Have Reached the Arctic
- 2021
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Ingår i: Environmental Science and Technology Letters. - : American Chemical Society. - 2328-8930. ; 8:9, s. 753-759
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Tidskriftsartikel (refereegranskat)abstract
- Chlorinated paraffins (CPs) were analyzed in marine wildlife from Greenland, Iceland, and the Swedish west coast. CPs up to C29 were detected in the samples from the Arctic, indicating long-range transport of an industrial chemical group with a 2-million-ton annual production volume. CP concentrations were generally higher in biota from the Swedish west coast. The Sweden/Arctic concentration ratios for very-short-chain (vSCCPs, C<10), short-chain (SCCPs, C10-13), medium-chain (MCCPs, C14-17), and long-chain CPs (LCCPs, C>17) in cetacean and bivalve species were in the range of 3.6-150, 5-29, 3-11, and 11-450, respectively. For the first time, fetal accumulation of four CP classes was found, whereby concentrations were 3.4 to 4.5 times lower in the fetus relative to the pregnant female minke whale. Cetacean blubber contained a higher proportion of higher chlorinated CPs compared to muscle tissue, while muscle contained higher lipid-normalized concentrations of longer chain CPs than blubber tissue. LCCPs predominated (52% of total CPs) in the muscle of a killer whale from Swedish waters, which is the first report where concentrations of LCCPs surpassed those of other CPs in marine mammals. This study shows that, like other CP classes, LCCPs are Arctic contaminants that may adversely affect biota in this remote region. © 2021 The Authors.
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| 10. |
- Chibwe, Leah, et al.
(författare)
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C12-30 alpha-Bromo-Chloro Alkenes : Characterization of a Poorly Identified Flame Retardant and Potential Environmental Implications
- 2019
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 53:18, s. 10835-10844
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Tidskriftsartikel (refereegranskat)abstract
- Bromo-chloro alkenes (Br-Cl PXAs) have been used for over 30 years as flame retardants and are listed on several national chemical inventories. Very little publicly available information is available on Br-Cl PXAs, and thus preliminary ecological risk screening is challenging due to the lack of basic information such as molecular structure and associated physicochemical properties. Due to their likely similarity with chlorinated paraffins (CPs), Br-Cl PXAs may pose a similar environmental hazard. Several structural databases list such substances as alkenes, although the industrial synthesis involves halogenation of linear alpha-olefins and would be expected to produce linear alkanes. In this study, a combination of high-resolution separation and mass spectrometric techniques were used to characterize a Br-Cl PXA industrial technical product, C12-30 bromo-chloro alpha-alkenes (CAS RN 68527-01-5). The results show this product is dominated by C-18 carbon chain lengths, substituted with 3-7 chlorine atoms and 1-3 bromine atoms on an alkane chain. Long-chain C-18 chlorinated paraffins are also present, although they represent a relatively minor component. Experimental log K-OW (6.9 to 8.6) and estimated log K-OA (10.5 to 13.5) and log K-AW (-5.1 to -0.6) partition coefficients suggest that this chemical will behave similarly to medium- and long-chain CPs as well as other persistent organic pollutants, such as highly chlorinated pesticides and polychlorinated biphenyls. The results of this study provide an initial step toward understanding the environmental behavior and persistence of Br-Cl PXAs, highlighting the need for further assessment and re-evaluation of the current structure(s) assigned to these compounds.
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