| 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. |
- Liu, Yangyang, et al.
(författare)
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Discriminating the impacts of vegetation greening and climate change on the changes in evapotranspiration and transpiration fraction over the Yellow River Basin
- 2023
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Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 904
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Tidskriftsartikel (refereegranskat)abstract
- Evapotranspiration (ET) is a vital parameter in terrestrial water-energy cycles. The transpiration fraction (TF) is defined as the ratio of transpiration (T) to evapotranspiration (ET), representing the contribution rate of vegetation transpiration to ecosystem ET. Quantifying the relative contributions of vegetation and climate change on the ET and TF dynamic is of great significance to better understand the water budget between the land and atmosphere. Here, we chose Yellow River Basin (YRB) as the study area and analyzed the spatiotemporal changes of ET, T, and TF from 1982 to 2015 using the Priestley-Taylor Jet Propulsion Laboratory (PT-JPL) model. Meanwhile, the relative contributions of vegetation and climate change to ET, T and TF change were quantified. Model evaluation showed that the PT-JPL model performs well in the simulation of ET and T. During 1982–2015, the average annual ET, T, and TF increased at a rate of 3.20 mm/a, 0.77 mm/a and 0.003/a over the YRB during 1982–2015, respectively. The regions with significant increases in ET, T and TF almost covered the whole study area except for the upper reaches of the YRB. Vegetation greening was the main factor for the increase of ET and TF in the YRB and enhanced ET and TF at a rate of 0.72 mm/a and 0.57/a, respectively, which mainly observed in the entire Loess Plateau region (over 50 % of the study area). Precipitation (PRE) was also the dominated factor contributing to the increase in ET and TF, and temperature (TEM) showed a positive correlation with the changes in ET and TF in the most areas of YRB, which jointly dominated ET changes in the upper reaches of the YRB and TF changes in the southern part of the basin. Except for the total effects, leaf area index (LAI) also indirectly promoted ET changes by affecting PRE, TEM and relative humidity (RH). While wind speed (WS) and radiation (RAD) had a relatively weak regulatory effect on the changes in ET and TF. These findings were helpful for regional water resources management and formulating water resources-sustainable vegetation restoration strategies for local government.
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| 3. |
- Yang, Qinsong, et al.
(författare)
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Genomic basis of the distinct biosynthesis of β-glucogallin, a biochemical marker for hydrolyzable tannin production, in three oak species
- 2024
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Ingår i: New Phytologist. - : John Wiley & Sons. - 0028-646X .- 1469-8137. ; 242:6, s. 2702-2718
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Tidskriftsartikel (refereegranskat)abstract
- Hydrolyzable tannins (HTs), predominant polyphenols in oaks, are widely used in grape wine aging, feed additives, and human healthcare. However, the limited availability of a high-quality reference genome of oaks greatly hampered the recognition of the mechanism of HT biosynthesis. Here, high-quality reference genomes of three Asian oak species (Quercus variabilis, Quercus aliena, and Quercus dentata) that have different HT contents were generated. Multi-omics studies were carried out to identify key genes regulating HT biosynthesis. In vitro enzyme activity assay was also conducted. Dual-luciferase and yeast one-hybrid assays were used to reveal the transcriptional regulation. Our results revealed that β-glucogallin was a biochemical marker for HT production in the cupules of the three Asian oaks. UGT84A13 was confirmed as the key enzyme for β-glucogallin biosynthesis. The differential expression of UGT84A13, rather than enzyme activity, was the main reason for different β-glucogallin and HT accumulation. Notably, sequence variations in UGT84A13 promoters led to different trans-activating activities of WRKY32/59, explaining the different expression patterns of UGT84A13 among the three species. Our findings provide three high-quality new reference genomes for oak trees and give new insights into different transcriptional regulation for understanding β-glucogallin and HT biosynthesis in closely related oak species.
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| 4. |
- Han, Ziqi, et al.
(författare)
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Regulating the miscibility of donors/acceptors to manipulate the morphology and reduce non-radiative recombination energy loss enables efficient organic solar cells
- 2024
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Ingår i: Journal of Materials Chemistry C. - : ROYAL SOC CHEMISTRY. - 2050-7526 .- 2050-7534.
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Tidskriftsartikel (refereegranskat)abstract
- Due to the high exciton binding energy and relatively low charge carrier mobilities of organic photovoltaic materials, it is crucial to optimize the active layer morphology of organic solar cells (OSCs) to well juggle exciton dissociation and charge carrier transport, and inhibit charge carrier recombination for high power conversion efficiencies (PCEs). Herein, we efficiently improve the crystallinity and miscibility of fused ring electron acceptors (FREAs) via lengthening the side chains and developing four FREAs, BTP-nC8, BTP-C8, BTP-C12 and BTP-C20. The dual functions of lengthening the side chains of FREAs make PM6:FREA blend films present the tendency of first improving then deteriorating in crystallinity, phase separation, domain purity and thus charge carrier dynamics, which leads the JSC and FF of PM6:FREA-based OSCs to show the same trend along with the side-chain length of FREAs. More importantly, enhancing the miscibility between PM6 and FREA facilitates the spatial registry to reduce the formation and recombination rate of triplet excitons in the PM6:FREA blend films, thus inhibiting the non-radiative recombination for decreased Delta Enr, and then increasing VOC in OSCs. Among them, PM6:BTP-C8 based OSCs well balance the multiple impacts of lengthening the side chains to achieve the highest PCE of 17.77%. This work demonstrates that it is important to finely control the crystallinity and miscibility of organic photovoltaic materials to achieve high PCEs in OSCs. The miscibility and crystallinity of fused ring electron acceptors is regulated to study the effects on the morphology and energy loss of organic solar cells (OSCs). BTP-C8 based OSCs juggle multiple impacts to gain the best efficiency.
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| 5. |
- Wang, Zijun, et al.
(författare)
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Quantifying the Spatiotemporal Changes in Evapotranspiration and Its Components Driven by Vegetation Greening and Climate Change in the Northern Foot of Yinshan Mountain
- 2024
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Ingår i: Remote Sensing. - 2072-4292. ; 16:2
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Tidskriftsartikel (refereegranskat)abstract
- Evapotranspiration (E), a pivotal phenomenon inherent to hydrological and thermal dynamics, assumes a position of utmost importance within the intricate framework of the water–energy nexus. However, the quantitative study of E on a large scale for the “Grain for Green” projects under the backdrop of climate change is still lacking. Consequently, this study examined the interannual variations and spatial distribution patterns of E, transpiration (Et), and soil evaporation (Eb) in the Northern Foot of Yinshan Mountain (NFYM) between 2000 and 2020 and quantified the contributions of climate change and vegetation greening to the changes in E, Et, and Eb. Results showed that E (2.47 mm/a, p < 0.01), Et (1.30 mm/a, p < 0.01), and Eb (1.06 mm/a, p < 0.01) all exhibited a significant increasing trend during 2000–2020. Notably, vegetation greening emerged as the predominant impetus underpinning the augmentation of both E and Eb, augmenting their rates by 0.49 mm/a and 0.57 mm/a, respectively. In terms of Et, meteorological factors emerged as the primary catalysts, with temperature (Temp) assuming a predominant role by augmenting Et at a rate of 0.35 mm/a. Temp, Precipitation (Pre), and leaf area index (LAI) collectively dominated the proportional distribution of E, accounting for shares of 32.75%, 28.43%, and 25.01%, respectively. Within the spectrum of predominant drivers influencing Et, Temp exerted the most substantial influence, commanding the largest proportion at 33.83%. For Eb, the preeminent determinants were recognized as LAI and Temp, collectively constituting a substantial portion of the study area, accounting for 32.10% and 29.50%, respectively. The LAI exerted a pronounced direct influence on the Et, with no significant effects on E and bare Eb. Wind speed (WS) had a substantial direct impact on both E and Et. Pre exhibited a strong direct influence on E, Et, and Eb. Relative humidity (RH) significantly affected E directly. Temp primarily influenced Eb indirectly through radiation (Rad). Rad exerted a significant direct inhibitory effect on Eb. These findings significantly advanced our mechanistic understanding of how E and its components in the NFYM respond to climate change and vegetation greening, thus providing a robust basis for formulating strategies related to regional ecological conservation and water resources management, as well as supplying theoretical underpinnings for constructing sustainable vegetation restoration strategies involving water resources in the region.
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| 6. |
- Ba, Kun, et al.
(författare)
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Billiard Catalysis at Ti3C2 MXene/MAX Heterostructure for Efficient Nitrogen Fixation
- 2022
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Ingår i: Applied Catalysis B. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 317, s. 121755-
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Tidskriftsartikel (refereegranskat)abstract
- Electrocatalytic ammonia (NH3) conversion under ambient atmosphere is crucial to mimic the nature's nitrogen cycle. But currently it is always interrupted by the HER process which is more competitive. Herein, we tactically cultivate a series of incompletely etched Ti3AlC2 MAX / Ti3C2 MXene based heterostructure catalysts whose composition can be finely tuned through regulation of the LiF percentage in mixed chemical etching agent. Notably, the surface potential difference between MAX and MXene is ~40 mV, indicating that the electron can be readily transferred from MAX to MXene across the interfaces, which is favorable for N2 fixation, yielding an outstanding Faradic efficiency of 36.9%. Furthermore, density functional theory calculations reveal the billiard-like catalysis mechanism, where the intermediates are alternatively adsorbed on MAX or MXene surfaces. Meanwhile, the rate-determining step of *NH → *NH2 possesses an energy barrier of 0.96 eV on the hetero-interface which follows associative distal mechanism. This work opens a new frontier of heterostructured catalyst for balancing electrical conductivity and catalytic activity in electrocatalysis.
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| 7. |
- Li, Honglian, et al.
(författare)
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Heparanase Modulates Chromatin Accessibility
- 2023
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Ingår i: Cells. - : MDPI. - 2073-4409. ; 12:6
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Tidskriftsartikel (refereegranskat)abstract
- Heparanase is the sole endoglucuronidase that degrades heparan sulfate in the cell surface and extracellular matrix (ECM). Several studies have reported the localization of heparanase in the cell nucleus, but the functional role of the nuclear enzyme is still obscure. Subjecting mouse embryonic fibroblasts (MEFs) derived from heparanase knockout (Hpse-KO) mice and applying transposase-accessible chromatin with sequencing (ATAC-seq), we revealed that heparanase is involved in the regulation of chromatin accessibility. Integrating with genome-wide analysis of chromatin states revealed an overall low activity in the enhancer and promoter regions of Hpse-KO MEFs compared with wild-type (WT) MEFs. Western blot analysis of MEFs and tissues derived from Hpse-KO vs. WT mice confirmed reduced expression of H3K27ac (acetylated lysine at N-terminal position 27 of the histone H3 protein). Our results offer a mechanistic explanation for the well-documented attenuation of inflammatory responses and tumor growth in Hpse-KO mice.
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| 8. |
- Raj, Uday, et al.
(författare)
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A study of thermal comfort enhancement using three energy efficient personalized heating strategies at two low indoor temperatures
- 2018
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Ingår i: Building and Environment. - : Pergamon Press. - 0360-1323 .- 1873-684X. ; 143, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- There is great potential to apply personalized heating for saving energy and enhancing individual thermal comfort in buildings during cold weather. This study investigated the enhancement of thermal comfort of occupants using personalized heating systems at low indoor temperatures. Three personalized heating systems are chosen for this work, i.e., a radiant heating panel with a heated table pad (denoted as HB1), a heated chair with a heated floor mattress (denoted as HB2), and electrical heating clothing (a heated jacket and trousers, denoted as EHC). The effectiveness of three selected heating systems on overall/local body thermal comfort of female occupants under two indoor temperatures of 15 and 18 degrees C has been investigated. Total energy consumption of these heating systems has also been examined and compared. Thermal acceptability of EHC was better than HB1 and HB2 at both two temperatures. Overall thermal sensation vote (TSV) in EHC was significantly better than that in HB1. Mean skin temperature remained within the thermal comfort range (32-34 degrees C). In order to achieve thermal comfort on 70% and 80% of the inhabitants at various body parts, local body TSVs should be within - 0.43 to 1.87 and - 0.36 to 1.87, respectively. Further, EHC consumed < 15 W power, which accounts for only 4.4% and 14.8% of the total power consumed by HB1 and HB2, respectively. Based on the evidenced thermal comfort improvement potential and low power consumption in EHC, it is thus recommended to use EHC for the thermal comfort enhancement of inhabitants under low indoor temperatures.
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| 9. |
- Raj, Uday, et al.
(författare)
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Personal cooling strategies to improve thermal comfort in warm indoor environments: comparison of a conventional desk fan and air ventilation clothing
- 2018
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Ingår i: Energy and Buildings. - : Elsevier BV. - 0378-7788 .- 1872-6178. ; 174, s. 439-451
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Tidskriftsartikel (refereegranskat)abstract
- The study examined and compared the performance of two personalized cooling strategies (conventional desk fan [DF] and air ventilation clothing [VC]) in three warm indoor environments. Two cooling methods were selected so that the effect of different local body parts cooling can be analysed on overall thermal comfort of female participants. Three warm indoor conditions (28.0, 30.0 and 32.0 °C; 50% RH) were selected with an aim to determine maximum possible air temperature which can be maintained indoors without compromising with thermal comfort of inhabitants. Results showed that performance of both the two cooling methods are similar in terms of perceptual responses and mean skin temperatures at all three air temperatures. Mean torso temperatures in VC were significantly lower than those in DF at three studied indoor temperatures. It was concluded that the effect of torso cooling on overall sensations was equivalent to combined forehead-hand cooling for the studied indoor conditions. VC is recommended for indoor and normal office work environments with air temperatures up to 32.0 °C because it can save significant cooling energy as compared to conventional desk fans.
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| 10. |
- Ren, Hanyu, et al.
(författare)
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Vegetation response to changes in climate across different climate zones in China
- 2023
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Ingår i: Ecological Indicators. - 1470-160X .- 1872-7034. ; 155
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Tidskriftsartikel (refereegranskat)abstract
- Vegetation growth is sensitive to climate change. The complex climate types of China pose great challenges to the sustainable management of vegetation on global change. Therefore, this study used Enhanced Vegetation Index (EVI) as an indicator to explore the spatiotemporal dynamics of vegetation and their driving factors in different climatic zones of China to provide theoretical support for sustainable vegetation management in different climate zones in the future. The results showed that vegetation exhibited considerable clustering patterns in the country, with high and low values concentrated in the eastern and western regions, respectively. From 2001 to 2020, both at regional and pixel scales, vegetation in China showed a significant greening trend. EVI displayed a noticeable increase within temperate and subtropical areas. The only exception is observed in the eastern coastal area of the North China Plain and Yangtze River Delta region, which experienced evident degradation trend. During this period, China's climate showed an overall trend towards warming and humidification with drying trends observed mainly over the western regions. The impact of climate changes resulted in EVI dynamics that vary over time and space. The vegetation change in China was mainly derived by changes in precipitation and radiation rather than temperature, especially in temperate and subfrigid regions. Precipitation was the main driving factor for vegetation greening in tropical and temperate regions, while radiation and temperature were the dominant climate factor for vegetation greening in subfrigid and subtropical regions, respectively. When precipitation was no longer a limiting factor for vegetation growth, the effect of temperature or radiation increases. In addition, the positive impact of precipitation on plant growth in temperate regions was much greater than that of radiation and temperature, and this difference was much greater than in tropical, subtropical, and subfrigid regions.
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