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| 2. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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| 3. |
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| 4. |
- Zhang, Li, et al.
(författare)
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Numerical simulation of natural convection and heat transfer in a molten pool with embedded cooling tubes
- 2022
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Ingår i: Frontiers in Energy Research. - : Frontiers Media SA. - 2296-598X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- This study described the natural circulation and heat transfer of a molten pool in a specifically designed core catcher conceived for a pressurized water reactor. In addition to external cooling, the core catcher features internal cooling tubes embedded in the molten pool. To investigate the coolability in such a configuration, first, a full-scale core catcher simulation is conducted to give a preliminary study under a real SA situation. Results illustrated that cooling efficiency can be remarkably enhanced due to the inner tubes. Then a test facility of the 2D slice with the geometrical scaled factor of 1:4 has been developed, and molten salt (NaNO3-KNO3) experiments will be implemented in the near future. This study also performed a pre-test simulation using molten NaNO3-KNO3 as a stimulant to study the heat transfer and flow characteristics of the salt pool. The melt convection in the test section was represented by a two-dimensional mesh with a WMLES turbulence model using the FLUENT code. The simulation captured the heat transfer enhancement by the cooling tubes as expected, and the results would help decide the proper test matrix and improvement of instrumentation required to obtain the necessary data for code validation.
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| 5. |
- Bentham, James, et al.
(författare)
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A century of trends in adult human height
- 2016
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Ingår i: eLIFE. - 2050-084X. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Being taller is associated with enhanced longevity, and higher education and earnings. We reanalysed 1472 population-based studies, with measurement of height on more than 18.6 million participants to estimate mean height for people born between 1896 and 1996 in 200 countries. The largest gain in adult height over the past century has occurred in South Korean women and Iranian men, who became 20.2 cm (95% credible interval 17.522.7) and 16.5 cm (13.319.7) taller, respectively. In contrast, there was little change in adult height in some sub-Saharan African countries and in South Asia over the century of analysis. The tallest people over these 100 years are men born in the Netherlands in the last quarter of 20th century, whose average heights surpassed 182.5 cm, and the shortest were women born in Guatemala in 1896 (140.3 cm; 135.8144.8). The height differential between the tallest and shortest populations was 19-20 cm a century ago, and has remained the same for women and increased for men a century later despite substantial changes in the ranking of countries.
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| 6. |
- Bentham, James, et al.
(författare)
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A century of trends in adult human height
- 2016
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Ingår i: eLIFE. - : eLife Sciences Publications Ltd. - 2050-084X. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Being taller is associated with enhanced longevity, and higher education and earnings. We reanalysed 1472 population-based studies, with measurement of height on more than 18.6 million participants to estimate mean height for people born between 1896 and 1996 in 200 countries. The largest gain in adult height over the past century has occurred in South Korean women and Iranian men, who became 20.2 cm (95% credible interval 17.5–22.7) and 16.5 cm (13.3– 19.7) taller, respectively. In contrast, there was little change in adult height in some sub-Saharan African countries and in South Asia over the century of analysis. The tallest people over these 100 years are men born in the Netherlands in the last quarter of 20th century, whose average heights surpassed 182.5 cm, and the shortest were women born in Guatemala in 1896 (140.3 cm; 135.8– 144.8). The height differential between the tallest and shortest populations was 19-20 cm a century ago, and has remained the same for women and increased for men a century later despite substantial changes in the ranking of countries.
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| 7. |
- de Nooijer, Wesley, et al.
(författare)
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Evaluation of Arctic warming in mid-Pliocene climate simulations
- 2020
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Ingår i: Climate of the Past. - : Copernicus GmbH. - 1814-9324 .- 1814-9332. ; 16:6, s. 2325-2341
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Tidskriftsartikel (refereegranskat)abstract
- Palaeoclimate simulations improve our understanding of the climate, inform us about the performance of climate models in a different climate scenario, and help to identify robust features of the climate system. Here, we analyse Arctic warming in an ensemble of 16 simulations of the mid-Pliocene Warm Period (mPWP), derived from the Pliocene Model Intercomparison Project Phase 2 (PlioMIP2). The PlioMIP2 ensemble simulates Arctic (60-90 degrees N) annual mean surface air temperature (SAT) increases of 3.7 to 11.6 degrees C compared to the pre-industrial period, with a multimodel mean (MMM) increase of 7.2 degrees C. The Arctic warming amplification ratio relative to global SAT anomalies in the ensemble ranges from 1.8 to 3.1 (MMM is 2.3). Sea ice extent anomalies range from -3.0 to -10.4 x 10(6) km(2), with a MMM anomaly of -5.6 x 10 6 km(2), which constitutes a decrease of 53 % compared to the pre-industrial period. The majority (11 out of 16) of models simulate summer seaice-free conditions (<= 1 x 10(6) km(2)) in their mPWP simulation. The ensemble tends to underestimate SAT in the Arctic when compared to available reconstructions, although the degree of underestimation varies strongly between the simulations. The simulations with the highest Arctic SAT anomalies tend to match the proxy dataset in its current form better. The ensemble shows some agreement with reconstructions of sea ice, particularly with regard to seasonal sea ice. Large uncertainties limit the confidence that can be placed in the findings and the compatibility of the different proxy datasets. We show that while reducing uncertainties in the reconstructions could decrease the SAT data-model discord substantially, further improvements are likely to be found in enhanced boundary conditions or model physics. Lastly, we compare the Arctic warming in the mPWP to projections of future Arctic warming and find that the PlioMIP2 ensemble simulates greater Arctic amplification than CMIP5 future climate simulations and an increase instead of a decrease in Atlantic Meridional Overturning Circulation (AMOC) strength compared to pre-industrial period. The results highlight the importance of slow feedbacks in equilibrium climate simulations, and that caution must be taken when using simulations of the mPWP as an analogue for future climate change.
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| 8. |
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| 9. |
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| 10. |
- Ji, Mengwei, et al.
(författare)
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Recent Advances in Organic Photovoltaic Materials Based on Thiazole-Containing Heterocycles
- 2023
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Ingår i: Macromolecular Rapid Communications. - 1022-1336 .- 1521-3927. ; 44:13
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Forskningsöversikt (refereegranskat)abstract
- Organic solar cells (OSCs) have achieved great progress, driven by the rapid development of wide bandgap electron donors and narrow bandgap non-fullerene acceptors (NFAs). Among a large number of electron-accepting (A) building blocks, thiazole (Tz) and its derived fused heterocycles have been widely used to construct photovoltaic materials, especially conjugated polymers. Benefiting from the electron deficiency, rigidity, high planarity, and enhanced intra/intermolecular interactions of Tz-containing heterocycles, some related photovoltaic materials exhibit proper energy levels, optimized molecular aggregation, and active layer morphology, leading to excellent photovoltaic performance. This review focuses on the progress of Tz-based photovoltaic materials in the field of OSCs. First, the Tz-based donor and acceptor photovoltaic materials are reviewed. Then, the materials based on promising Tz-containing heterocycles, mainly including thiazolo[5,4-d]thiazole (TzTz), benzo[1,2-d:4,5-d’]bis(thiazole) (BBTz), and benzo[d]thiazole (BTz) are summarized and discussed. In addition, the new emerging Tz-fused structures and their application in OSCs are introduced. Finally, perspectives and outlooks for the further development of Tz-containing heterocycle-based photovoltaic materials are proposed.
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| 11. |
- 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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| 12. |
- Liu, Wei, et al.
(författare)
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Coherent dynamics of multi-spin V-B(-) center in hexagonal boron nitride
- 2022
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Ingår i: Nature Communications. - : Nature Portfolio. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Hexagonal boron nitride (hBN) has recently been demonstrated to contain optically polarized and detected electron spins that can be utilized for implementing qubits and quantum sensors in nanolayered-devices. Understanding the coherent dynamics ofmicrowave driven spins in hBN is of crucial importance for advancing these emerging new technologies. Here, we demonstrate and study the Rabi oscillation and related phenomena of a negatively charged boron vacancy (V-B(-)) spin ensemble in hBN. We report on different dynamics of the V-B(-) spins at weak and strong magnetic fields. In the former case the defect behaves like a single electron spin system, while in the latter case it behaves like a multi-spin system exhibiting multiple-frequency dynamical oscillation as beat in the Ramsey fringes. We also carry out theoretical simulations for the spin dynamics of V-B(-) and reveal that the nuclear spins can be driven via the strong electron nuclear coupling existing in V-B(-) center, which can be modulated by the magnetic field and microwave field.
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| 13. |
- Xia, Shaopan, et al.
(författare)
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Storage, patterns and influencing factors for soil organic carbon in coastal wetlands of China
- 2022
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Ingår i: Global Change Biology. - : John Wiley & Sons. - 1354-1013 .- 1365-2486. ; 28:20, s. 6065-6085
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Tidskriftsartikel (refereegranskat)abstract
- Soil organic carbon (SOC) in coastal wetlands, also known as "blue C," is an essential component of the global C cycles. To gain a detailed insight into blue C storage and controlling factors, we studied 142 sites across ca. 5000 km of coastal wetlands, covering temperate, subtropical, and tropical climates in China. The wetlands represented six vegetation types (Phragmites australis, mixed of P. australis and Suaeda, single Suaeda, Spartina alterniflora, mangrove [Kandelia obovata and Avicennia marina], tidal flat) and three vegetation types invaded by S. alterniflora (P. australis, K. obovata, A. marina). Our results revealed large spatial heterogeneity in SOC density of the top 1-m ranging 40-200 Mg C ha(-1), with higher values in mid-latitude regions (25-30 degrees N) compared with those in both low- (20 degrees N) and high-latitude (38-40 degrees N) regions. Vegetation type influenced SOC density, with P. australis and S. alterniflora having the largest SOC density, followed by mangrove, mixed P. australis and Suaeda, single Suaeda and tidal flat. SOC density increased by 6.25 Mg ha(-1) following S. alterniflora invasion into P. australis community but decreased by 28.56 and 8.17 Mg ha(-1) following invasion into K. obovata and A. marina communities. Based on field measurements and published literature, we calculated a total inventory of 57 x 10(6) Mg C in the top 1-m soil across China's coastal wetlands. Edaphic variables controlled SOC content, with soil chemical properties explaining the largest variance in SOC content. Climate did not control SOC content but had a strong interactive effect with edaphic variables. Plant biomass and quality traits were a minor contributor in regulating SOC content, highlighting the importance of quantity and quality of OC inputs and the balance between production and degradation within the coastal wetlands. These findings provide new insights into blue C stabilization mechanisms and sequestration capacity in coastal wetlands.
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| 14. |
- Zhang, Lixiu, et al.
(författare)
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Advances in the Application of Perovskite Materials
- 2023
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Ingår i: NANO-MICRO LETTERS. - : SHANGHAI JIAO TONG UNIV PRESS. - 2311-6706. ; 15:1
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Forskningsöversikt (refereegranskat)abstract
- Nowadays, the soar of photovoltaic performance of perovskite solar cells has set off a fever in the study of metal halide perovskite materials. The excellent optoelectronic properties and defect tolerance feature allow metal halide perovskite to be employed in a wide variety of applications. This article provides a holistic review over the current progress and future prospects of metal halide perovskite materials in representative promising applications, including traditional optoelectronic devices (solar cells, light-emitting diodes, photodetectors, lasers), and cutting-edge technologies in terms of neuromorphic devices (artificial synapses and memristors) and pressure-induced emission. This review highlights the fundamentals, the current progress and the remaining challenges for each application, aiming to provide a comprehensive overview of the development status and a navigation of future research for metal halide perovskite materials and devices.
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| 15. |
- Bai, Licheng, et al.
(författare)
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Explaining the Size Dependence in Platinum-Nanoparticle-Catalyzed Hydrogenation Reactions
- 2016
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Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 55:50, s. 15656-15661
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogenation reactions are industrially important reactions that typically require unfavorably high H-2 pressure and temperature for many functional groups. Herein we reveal surprisingly strong size-dependent activity of Pt nanoparticles (PtNPs) in catalyzing this reaction. Based on unambiguous spectral analyses, the size effect has been rationalized by the size-dependent d-band electron structure of the PtNPs. This understanding enables production of a catalyst with size of 1.2 nm, which shows a sixfold increase in turnover frequency and 28-fold increase in mass activity in the regioselective hydrogenation of quinoline, compared with PtNPs of 5.3 nm, allowing the reaction to proceed under ambient conditions with unprecedentedly high reaction rates. The size effect and the synthesis strategy developed herein may provide a general methodology in the design of metal-nanoparticle-based catalysts for a broad range of organic syntheses.
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| 16. |
- Bashir, Muwada Bashir Awad, et al.
(författare)
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Computational phenotyping of obstructive airway diseases: protocol for a systematic review
- 2022
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Ingår i: Systematic Reviews. - : Springer Nature. - 2046-4053. ; 11:1
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Forskningsöversikt (refereegranskat)abstract
- Background: Over the last decade, computational sciences have contributed immensely to characterization of phenotypes of airway diseases, but it is difficult to compare derived phenotypes across studies, perhaps as a result of the different decisions that fed into these phenotyping exercises. We aim to perform a systematic review of studies using computational approaches to phenotype obstructive airway diseases in children and adults.Methods and analysis: We will search PubMed, Embase, Scopus, Web of Science, and Google Scholar for papers published between 2010 and 2020. Conferences proceedings, reference list of included papers, and experts will form additional sources of literature. We will include observational epidemiological studies that used a computational approach to derive phenotypes of chronic airway diseases, whether in a general population or in a clinical setting. Two reviewers will independently screen the retrieved studies for eligibility, extract relevant data, and perform quality appraisal of included studies. A third reviewer will arbitrate any disagreements in these processes. Quality appraisal of the studies will be undertaken using the Effective Public Health Practice Project quality assessment tool. We will use summary tables to describe the included studies. We will narratively synthesize the generated evidence, providing critical assessment of the populations, variables, and computational approaches used in deriving the phenotypes across studiesConclusion: As progress continues to be made in the area of computational phenotyping of chronic obstructive airway diseases, this systematic review, the first on this topic, will provide the state of the art on the field and highlight important perspectives for future works.Ethics and dissemination: No ethical approval is needed for this work is based only on the published literature and does not involve collection of any primary or human data.
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| 17. |
- 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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| 18. |
- Berntell, Ellen, et al.
(författare)
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Mid-Pliocene West African Monsoon rainfall as simulated in the PlioMIP2 ensemble
- 2021
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Ingår i: Climate of the Past. - : Copernicus GmbH. - 1814-9324 .- 1814-9332. ; 17:4, s. 1777-1794
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Tidskriftsartikel (refereegranskat)abstract
- The mid-Pliocene warm period (mPWP; ∼3.2 million years ago) is seen as the most recent time period characterized by a warm climate state, with similar to modern geography and ∼400 ppmv atmospheric CO2 concentration, and is therefore often considered an interesting analogue for near-future climate projections. Paleoenvironmental reconstructions indicate higher surface temperatures, decreasing tropical deserts, and a more humid climate in West Africa characterized by a strengthened West African Monsoon (WAM). Using model results from the second phase of the Pliocene Modelling Intercomparison Project (PlioMIP2) ensemble, we analyse changes of the WAM rainfall during the mPWP by comparing them with the control simulations for the pre-industrial period. The ensemble shows a robust increase in the summer rainfall over West Africa and the Sahara region, with an average increase of 2.5 mm/d, contrasted by a rainfall decrease over the equatorial Atlantic. An anomalous warming of the Sahara and deepening of the Saharan Heat Low, seen in >90 % of the models, leads to a strengthening of the WAM and an increased monsoonal flow into the continent. A similar warming of the Sahara is seen in future projections using both phase 3 and 5 of the Coupled Model Intercomparison Project (CMIP3 and CMIP5). Though previous studies of future projections indicate a west–east drying–wetting contrast over the Sahel, PlioMIP2 simulations indicate a uniform rainfall increase in that region in warm climates characterized by increasing greenhouse gas forcing. We note that this effect will further depend on the long-term response of the vegetation to the CO2 forcing.
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| 19. |
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| 20. |
- Chen, Guo-Qiang, et al.
(författare)
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Polyhydroxyalkanoates and Other Biopolymers
- 2019
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Ingår i: Biomacromolecules. - : AMER CHEMICAL SOC. - 1525-7797 .- 1526-4602. ; 20:9, s. 3211-3212
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 21. |
- Deng, Yucheng, et al.
(författare)
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A numerical study on the levitation system for droplet preparation in a fuel-coolant interaction experiment
- 2023
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Ingår i: Progress in nuclear energy (New series). - : Elsevier BV. - 0149-1970 .- 1878-4224. ; 159
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Tidskriftsartikel (refereegranskat)abstract
- The MISTEE facility at KTH was designed to investigate the process and phenomena of a molten droplet falling into a water pool that may be encountered in fuel-coolant interactions (FCI) during a severe accident of light water reactors. An aerodynamic levitation mechanism is proposed to hold the molten droplet during its preparation (melting and heating up to a prescribed temperature) in an induction furnace. The crucible is flushed with argon through an injection nozzle at the bottom to prevent the droplet from falling out of the crucible. A numerical simulation of the aerodynamic levitation system is performed in the present study with the objective of determining and optimizing the design. The problem was simplified as an isothermal two-phase flow in an axisymmetric geometry. The simulation is realized through ANSYS Fluent v17 platform, which employs the VOF method to track interfaces between two phases and the SST k-omega model to describe turbulence flow of argon gas. The numerical model is validated against tests performed in the MISTEE facility after mesh sensitivity study. It is then applied to investigate the impacts of various parameters on the facility levitation capability and the droplet stability. According to the simulation results, stable molten droplets can be obtained in the designed experimental setup. The simulation also provides the appropriate values of argon inlet velocity and sample mass at which a stable droplet can be obtained inside the crucible before its discharge. Either higher or lower inlet velocity will destabilize the formation of the droplet. Considering the temperature-dependent melt properties, both surface tension and viscosity affect the movement and deformation of the molten droplet. The wettability of melt on the crucible wall is critical to droplet formation, and it is found that a poor wettability can ensure the levitation of droplet.
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| 22. |
- Deng, Yucheng, et al.
(författare)
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An experimental study on droplet quench and steam explosion in boric acid solutions
- 2023
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Ingår i: Progress in nuclear energy (New series). - : Elsevier BV. - 0149-1970 .- 1878-4224. ; 166
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Tidskriftsartikel (refereegranskat)abstract
- Boric acid (H3BO3) is widely adopted as an additive in the coolant of light water reactors for reactivity control, but its effect on fuel coolant interactions (FCI) during severe accidents (especially on steam explosion) was rarely investigated. To examine the effect of the boric acid additive in coolant on steam explosion, a series of molten droplet-coolant interaction tests using H3BO3 solutions (with concentration ranging from 0-3.2% by weight) is carried out in the present study. The characteristics of melt-coolant interactions are the occurrence probability of typical phenomena (no fragmentation, minor fragmentation, or spontaneous steam explosion), lateral deformation ratio, quench depth, pressure impulse and debris particle size distribution. The statistical data of such characteristics are obtained through repeating 20 runs of the same test category. The experimental results show that the H3BO3 addition in coolant has various impacts on the above-mentioned characteristics of melt-coolant interactions, depending on the H3BO3 concentration. In particular, the probability of steam explosion sightly decreases as the H3BO3 concentration increases from zero to 1.2 wt.%, but significantly increases as the H3BO3 concentration further increases to 3.2 wt.% trough 2.2 wt.%. Namely, the inhibiting effect of boric acid on steam explosion is diminishing with increasing H3BO3 concentration beyond 1.2 wt.%. It is also found that both melt and coolant temperatures are crucial parameters impacting the likelihood and energetics of steam explosion.
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| 23. |
- Deng, Yucheng, et al.
(författare)
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An Experimental study on steam explosion of multiple droplets in different chemical solutions
- 2024
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Ingår i: International Journal of Heat and Mass Transfer. - : Elsevier BV. - 0017-9310 .- 1879-2189. ; 226
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Tidskriftsartikel (refereegranskat)abstract
- Motivated by the interest in steam explosion in chemical solutions and seawater, a series of tests were carried out in the MISTEE facility at KTH to investigate steam explosion characteristics as multiple molten droplets of tin were falling through a coolant pool containing deionized water, boric acid solution, neutral solution of boric acid and sodium phosphate, and seawater, separately. The experimental results revealed distinct and complex characteristics of steam explosion of multiple droplets, which were not observed in previous single-droplet steam explosion experiments. The tin melt samples of 5 g and 20 g were employed to formulate different numbers of multiple droplets. In the test with 5 g melt, steam explosion was more energetic at a deeper explosion location − a similar trend found in the single-droplet steam explosion test with 1 g melt. However, the test of 20 g melt did not show a clear trend in a wide range of explosion depth. The peak pressure and impulse increased with increasing mass of melt sample. The steam explosion occurred more closely to the coolant pool surfaces in the seawater and chemical solutions than in deionized water. Steam explosion intensity was significantly reduced in a neutral solution containing 1.2 wt.% boric acid and sodium phosphate. The influence of the chemical solutions on steam explosion was diminishing in the tests with multiple droplets.
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| 24. |
- Deng, Yucheng, et al.
(författare)
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An experimental study on the effect of chemical additives in coolant on steam explosion
- 2024
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Ingår i: International Journal of Heat and Mass Transfer. - : Elsevier Ltd. - 0017-9310 .- 1879-2189. ; 218
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Tidskriftsartikel (refereegranskat)abstract
- In assessment of severe accident risk in light water reactors (LWRs), steam explosion is a nonnegligible phenomenon following a relocation of core melt (corium) into coolant, and thus various research efforts have been paid to steam explosion. There had been numerous studies showing that the occurrence of steam explosions is influenced by several factors such as melt and coolant temperatures, melt materials, non-condensable gasses, etc. However, most of the existing experiments used deionized (DI) water or tap water as coolant, with little consideration of the effect of chemicals (e.g. boric acid, sodium hydroxide, sodium phosphate) commonly applied in reactor coolant. To examine the effect of the chemical additives in coolant on steam explosion, the present study performs a series of molten Tin droplet-coolant interaction tests using DI water and different chemical solutions, including H3BO3 solutions, NaOH + H3BO3 neutral solutions, and Na3PO4 + H3BO3 neutral solutions. The experimental results show that adding NaOH and Na3PO4 in boric acid solution significantly affects the occurrence probability of spontaneous steam explosion, because of the presence of PO43− and H+ ions. When different solutions have equivalent concentrations of H3BO3, the peak pressure values of the spontaneous steam explosion of Sn droplets are similar among various solutions. Compared with those in DI water, steam explosion in the chemical solutions occurs predominantly within a narrow range of depth from 28 mm to 40 mm and produces a much higher peak pressure. This implies that more energetic steam explosions may occur in the chemical solutions.
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| 25. |
- Deng, Yucheng, et al.
(författare)
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An experimental study on the effect of coolant salinity on steam explosion
- 2024
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Ingår i: Annals of Nuclear Energy. - : Elsevier BV. - 0306-4549 .- 1873-2100. ; 201
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Tidskriftsartikel (refereegranskat)abstract
- The steam explosion plays an essential role in the safety analysis of light water reactors (LWRs). Some studies have demonstrated that the occurrence of steam explosions is dependent on many factors such as melt and coolant temperatures, melt and coolant properties, non -condensable gases, etc. After the Fukushima accident, seawater as an emergency coolant and its impact on fuel coolant interactions are receiving attention. However, there is still little knowledge on the impact of seawater on steam explosion. The present study is intended to examine the effect of coolant salinity on steam explosion through a series of tests with single molten droplet falling in different coolant pools (DI water, and seawater at different salinities from 7.7 g/kg to 35 g/kg). The experimental results reveal that the salinity of coolant significantly influences the probability of spontaneous steam explosion of molten tin droplets. The probability of steam explosion generally increases with increasing salinity from 0 to 17.5 g/kg. The molten droplet in seawater experiences more pronounced deformation at same depth before the vapor film of the droplet collapses. What's more, the peak pressure generated by steam explosion in seawater is notably higher than that in DI water. The fragmentation of molten tin droplet after the explosion is enhanced accordingly.
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| 26. |
- Duan, Chen, et al.
(författare)
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Comparative analysis of gene expression profiles between primary knee osteoarthritis and an osteoarthritis endemic to Northwestern China, Kashin-Beck disease.
- 2010
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Ingår i: Arthritis and Rheumatism. - : John Wiley & Sons. - 0004-3591 .- 1529-0131. ; 62:3, s. 771-780
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To investigate the differences in gene expression profiles of adult articular cartilage from patients with Kashin-Beck disease (KBD) versus those with primary knee osteoarthritis (OA).METHODS: The messenger RNA expression profiles of articular cartilage from patients with KBD, diagnosed according to the clinical criteria for KBD in China, were compared with those of cartilage from patients with OA, diagnosed according to the Western Ontario and McMaster Universities OA Index. Total RNA was isolated separately from 4 pairs of the KBD and OA cartilage samples, and the expression profiles were evaluated by Agilent 4x44k Whole Human Genome density oligonucleotide microarray analysis. The microarray data for selected transcripts were confirmed by quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) amplification.RESULTS: For 1.2 x 10(4) transcripts, corresponding to 58.4% of the expressed transcripts, 2-fold changes in differential expression were revealed. Expression levels higher in KBD than in OA samples were observed in a mean + or - SD 6,439 + or - 1,041 (14.6 + or - 2.4%) of the transcripts, and expression levels were lower in KBD than in OA samples in 6,147 + or - 1,222 (14.2 + or - 2.8%) of the transcripts. After application of the selection criteria, 1.85% of the differentially expressed genes (P < 0.001 between groups) were detected. These included 233 genes, of which 195 (0.4%) were expressed at higher levels and 38 (0.08%) were expressed at lower levels in KBD than in OA cartilage. Comparisons of the quantitative RT-PCR data supported the validity of our microarray data.CONCLUSION: Differences between KBD and OA cartilage exhibited a similar pattern among all 4 of the pairs examined, indicating the presence of disease mechanisms, mainly chondrocyte matrix metabolism, cartilage degeneration, and apoptosis induction pathways, which contribute to cartilage destruction in KBD.
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| 27. |
- Feng, Boya, et al.
(författare)
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Structural and Functional Insights into the Mode of Action of a Universally Conserved Obg GTPase
- 2014
-
Ingår i: PLoS biology. - : Public Library of Science (PLoS). - 1544-9173 .- 1545-7885. ; 12:5, s. e1001866-
-
Tidskriftsartikel (refereegranskat)abstract
- Obg proteins are a family of P-loop GTPases, conserved from bacteria to human. The Obg protein in Escherichia coli (ObgE) has been implicated in many diverse cellular functions, with proposed molecular roles in two global processes, ribosome assembly and stringent response. Here, using pre-steady state fast kinetics we demonstrate that ObgE is an anti-association factor, which prevents ribosomal subunit association and downstream steps in translation by binding to the 50S subunit. ObgE is a ribosome dependent GTPase; however, upon binding to guanosine tetraphosphate (ppGpp), the global regulator of stringent response, ObgE exhibits an enhanced interaction with the 50S subunit, resulting in increased equilibrium dissociation of the 70S ribosome into subunits. Furthermore, our cryo-electron microscopy (cryo-EM) structure of the 50S? ObgE? GMPPNP complex indicates that the evolutionarily conserved N-terminal domain (NTD) of ObgE is a tRNA structural mimic, with specific interactions with peptidyl-transferase center, displaying a marked resemblance to Class I release factors. These structural data might define ObgE as a specialized translation factor related to stress responses, and provide a framework towards future elucidation of functional interplay between ObgE and ribosome-associated (p) ppGpp regulators. Together with published data, our results suggest that ObgE might act as a checkpoint in final stages of the 50S subunit assembly under normal growth conditions. And more importantly, ObgE, as a (p) ppGpp effector, might also have a regulatory role in the production of the 50S subunit and its participation in translation under certain stressed conditions. Thus, our findings might have uncovered an under-recognized mechanism of translation control by environmental cues.
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| 28. |
- Fu, Pan, et al.
(författare)
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Metasurface Enabled On-Chip Generation and Manipulation of Vector Beams from Vertical Cavity Surface-Emitting Lasers
- 2023
-
Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; In Press
-
Tidskriftsartikel (refereegranskat)abstract
- Metasurface polarization optics that consist of 2D array of birefringent nano-antennas have proven remarkable capabilities to generate and manipulate vectorial fields with subwavelength resolution and high efficiency. Integrating this new type of metasurface with the standard vertical cavity surface-emitting laser (VCSEL) platform enables an ultracompact and powerful solution to control both phase and polarization properties of the laser on a chip, which allows to structure a VCSEL into vector beams with on-demand wavefronts. Here, this concept is demonstrated by directly generating versatile vector beams from commercially available VCSELs through on-chip integration of high-index dielectric metasurfaces. Experimentally, the versatility of the approach for the development of vectorial VCSELs are validated by implementing a variety of functionalities, including directional emission of multibeam with specified polarizations, vectorial holographic display, and vector vortex beams generations. Notably, the proposed vectorial VCSELs integrated with a single layer of beam shaping metasurface bypass the requirements of multiple cascaded optical components, and thus have the potential to promote the advancements of ultracompact, lightweight, and scalable vector beams sources, enriching and expanding the applications of VCSELs in optical communications, laser manipulation and processing, information encryption, and quantum optics.
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| 29. |
- Gong, Yaopeng, et al.
(författare)
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Density Measurement of Molten Drop With Aerodynamic Levitation and Laser Heating
- 2022
-
Ingår i: Frontiers in Energy Research. - : Frontiers Media SA. - 2296-598X. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Thermophysical properties of molten core materials (corium) are necessary input parameters of models and computer codes which predict the severe accident progression in light water reactors. The corium contains the components of UO2, ZrO2, Zr and Fe. The measurement of molten corium properties is a very challenging task due to high melting points of corium which can reach 3000 K. This paper presents a density measurement system for a molten drop based on techniques of aerodynamic levitation, laser heating and image processing. A sphere of alumina was firstly levitated by argon gas flow above a conical converging-diverging nozzle. The sphere was then heated up and melted into a liquid drop by a laser beam. The shape of the drop was recorded by a high-speed camera, and the density was calculated from image processing.
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| 30. |
- Gong, Yaopeng, et al.
(författare)
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Surface Tension Measurement of Molten Zirconia with Aerodynamic Levitation and Laser Heating
- 2023
-
Ingår i: Proceedings of the 30th International Conference on Nuclear Engineering "Nuclear, Thermal, and Renewables: United to Provide Carbon Neutral Power", ICONE 2023. - : American Society of Mechanical Engineers (ASME).
-
Konferensbidrag (refereegranskat)abstract
- Thermophysical properties of corium are required in models and computer codes to predict the severe accident progression in light water reactors. However, the measurement of molten corium properties is challenging due to high melting points. This paper presents a surface tension measurement system for molten zirconia based on techniques of aerodynamic levitation and laser heating. Zirconia is one of the main components in corium and aerodynamic levitation is a contactless method to avoid interactions between the sample and container wall at high temperatures. A sample of zirconia was levitated by argon gas flow above a conical converging-diverging nozzle and then melted into a droplet by laser beams. The oscillation of molten zirconia was imaged by a high-speed camera. The resonant frequency was then obtained through image processing. Finally, the surface tension was derived according to the Rayleigh formula.
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| 31. |
- Gong, Yaopeng, et al.
(författare)
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Viscosity measurement of molten alumina and zirconia using aerodynamic levitation, laser heating and droplet oscillation techniques
- 2023
-
Ingår i: Heliyon. - : Elsevier BV. - 2405-8440. ; 9:12
-
Tidskriftsartikel (refereegranskat)abstract
- Reliable thermophysical properties of core melt (corium) are essential for the accurate prediction of the severe accident progression in light water reactors. Zirconia is one of the most important materials in corium. Despite the high interest in the viscosity of molten zirconia, few experimental data have been reported due to its high melting temperature and high vapor pressure. In the present study, the viscosity of molten zirconia was measured using aerodynamic levitation, laser heating and droplet oscillation techniques. A material sample was levitated by argon gas flow in a conical nozzle and then melted into a droplet by laser beams. The initial quiescent droplet was forced to oscillate by the excitation of a loudspeaker, and the viscosity was deduced based on the characteristics of the droplet damped oscillation after the loudspeaker was turned off. The viscosity of molten alumina was first measured for verification of the measurement system. Afterwards the viscosity of molten zirconia was measured. The results showed that the viscosity of molten zirconia at melting temperature (2988K) was 12.87 ± 1.03 mPa s and decreased with increasing temperature. The measurement uncertainties are within 21 %.
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| 32. |
- Gossas, Thomas, et al.
(författare)
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The advantage of biosensor analysis over enzyme inhibition studies for slow dissociating inhibitors : characterization of hydroxamate-based matrix metalloproteinase-12 inhibitors
- 2013
-
Ingår i: MedChemComm. - : Royal Society of Chemistry (RSC). - 2040-2503 .- 2040-2511. ; 4:2, s. 432-442
-
Tidskriftsartikel (refereegranskat)abstract
- The kinetic characteristics of hydroxamate-based inhibitors of matrix metalloproteinase (MMP)-12 were explored using an SPR biosensor-based assay and enzyme inhibition analysis. These high-affinity inhibitors were shown to dissociate very slowly from the enzyme-inhibitor complex while a carboxylate analogue had a much faster dissociation rate, verifying the importance of the hydroxamate group for the slow dissociation. Progress curve enzyme inhibition analysis confirmed that the hydroxamate compounds but not the carboxylate compound acted as time-dependent inhibitors. The slow dissociation excluded steady-state estimation of IC50-values and K-i values but also made K-i values from progress curve analysis unreliable. Although a full characterization of the inhibitors using biosensor analysis was limited by slow dissociation, it provided kinetic and mechanistic information of relevance for MMP drug discovery and avoided some pitfalls of conventional enzyme inhibition assays.
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| 33. |
- Gu, Jian, et al.
(författare)
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TGF-beta-Induced CD4(+) Foxp3(+) T Cells Attenuate Acute Graft-versus-Host Disease by Suppressing Expansion and Killing of Effector CD8(+) Cells
- 2014
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Ingår i: Journal of Immunology. - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 193:7, s. 3388-3397
-
Tidskriftsartikel (refereegranskat)abstract
- The use of TGF-beta-induced CD4(+) Foxp3(+) T cells (induced regulatory T cells [iTregs]) is an important prevention and treatment strategy in autoimmune diseases and other disorders. However, the potential use of iTregs as a treatment modality for acute graft-versus-host disease (aGVHD) has not been realized because they may be unstable and less suppressive in this disease. We restudied the ability of iTregs to prevent and treat aGVHD in two mouse models. Our results showed that, as long as an appropriate iTreg-generation protocol is used, these iTregs consistently displayed a potent ability to control aGVHD development and reduce mortality in the aGVHD animal models. iTreg infusion markedly suppressed the engraftment of donor CD8(+) cells and CD4(+) cells, the expression of granzyme A and B, the cytotoxic effect of donor CD8(+) cells, and the production of T cell cytokines in aGVHD. Therefore, we conclude that as long as the correct methods for generating iTregs are used, they can prevent and even treat aGVHD.
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| 34. |
- Guo, Pengfei, et al.
(författare)
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Chloride Induced Secondary Passive Film Failure for Laser Additive Manufacturing Nickel-Based Superalloys during Electrochemical Machining
- 2023
-
Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 170:6
-
Tidskriftsartikel (refereegranskat)abstract
- We investigated the influence of chloride on the secondary passive film (SPF) on laser directed energy deposition Alloy 718 during electrochemical machining. The results show that SPF formed in chloride-containing electrolyte is more defective than that formed in chloride-free solution, due to the stepped-up cation ejection by chloride. Chloride accelerates the SPF failure via enhanced cation vacancy condensation, SPF dissolution and possibly via surface vacancy pairs' coalescence, restraining the formation of CrO3 and inducing a better surface quality than does the chloride-free electrolyte. Based on the Point Defect Model, a mechanism describing the influence of chloride on SPF was developed.
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| 35. |
- Guo, Qiang, et al.
(författare)
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A design study on an aerodynamic levitation system for droplet preparation in steam explosion experiment
- 2019
-
Ingår i: International Conference on Nuclear Engineering, Proceedings, ICONE. - : ASME Press. - 9784888983051
-
Konferensbidrag (refereegranskat)abstract
- In order to investigate the mechanisms of steam explosion which may occur during a severe accident of light water reactors (LWRs), the MISTEE facility was developed at Royal Institute Technology (KTH) to visualize the micro interactions of steam explosion when a single molten droplet was falling into a water pool. For preparation of a molten droplet, an aerodynamic levitation system was proposed to prevent the droplet from falling out of the crucible during heating in an induction furnace by injecting argon gas through a purging line connected to the bottom nozzle of the crucible. To support the design of such levitation system, a numerical simulation of the aerodynamic levitation system was performed using the CFD code ANASYS FLUENT v16.2. The problem was simplified as adiabatic two-phase flow dynamics in a 2-D axisymmetric geometry. The VOF method is employed to track the interface of two phases (liquid metal and argon gas), and the SST k-omega model was chosen for turbulence. Various characteristics of droplet dynamics in incorporated with argon gas flowrates through the crucible were examined in the numerical simulation. The simulation results suggested there exists an optimal range of argon gas flowrate for levitating a coherent shape of droplet in the crucible. The wall adhesion had a considerable effect on initiating the levitation of the droplet, which means the properties of the inside surface of the crucible may play an important role in the levitation and discharge of the droplet. Proof-of-concept tests were carried out on the prototype of the design, and it was confirmed that the levitation system was able to fulfill its function, i.e., to keep the droplet in the crucible during its melting process, although the actual argon gas flowrates for levitation was higher than the predicted ones, probably due to the leakage of flow path and heat transfer which were not considered in the simulation. Generally speaking, the numerical simulation did not only help understand the hydrodynamic characteristics of the levitation system, but also provided insights on operational control and improvement of the system.
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| 36. |
- Guo, Qiang, et al.
(författare)
-
An experimental study on quenching of metallic spheres in seawater
- 2023
-
Ingår i: Experimental Thermal and Fluid Science. - : Elsevier BV. - 0894-1777 .- 1879-2286. ; 148
-
Tidskriftsartikel (refereegranskat)abstract
- Motivated by quenching of melt droplets and debris particles in seawater during a hypothetical severe accident of light water reactors (LWRs), the quenching process of stainless-steel spheres in a seawater pool was investigated in the present study. The polished spheres were pre-heated up to 1000celcius in an induction furnace with inserted atmosphere, and then immersed into the subcooled water pool in a chamber made of transparent quartz. A thermocouple was embedded in the center of the sphere to measure the history of the sphere's temperature, while a high-speed camera was employed to record the quenching process and vapor film dynamics. Quantitative data, e.g. film thickness and oscillation, of the vapor film evolution during the quenching process were obtained through an image processing program developed on the MATLAB platform.The experimental results indicated that the quenching rate was higher in seawater than in deionized water, and the vapor film collapsed at a temperature higher than the Leidenfrost temperature in deionized water. The trend appeared more significant with increasing subcooling of water. The comparison of the quenched spheres suggested the surface of the sphere in seawater achieved higher degree of discoloration and roughening than that in deionized water, probably due to the additives of salt which change water properties. The image processing and analysis revealed that the vapor film had different thickness profile along the upper and lower hemispheres, and the averaged film thickness was smaller in seawater than in de-ionized water during the stage of stable film boiling. The vapor film was thinning and oscillating with time, and its fluctuations appeared different frequencies and amplitudes at the upper and lower locations, which may explain the mechanism of the earlier collapse of vapor film in the quenching process of a high-temperature sphere in seawater.
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| 37. |
- Guo, Qiang, et al.
(författare)
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Effects of salinity in coolant on steam explosion
- 2019
-
Ingår i: 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019. - : American Nuclear Society. ; , s. 4556-4567
-
Konferensbidrag (refereegranskat)abstract
- During a severe accident scenario of nuclear power plants, a steam explosion may occur when a substantial amount of molten core materials is rapidly ejected into a volatile coolant (water) pool, forming so-called Fuel-Coolant Interactions (FCI). The steam explosion poses a serious threat to the containment integrity. It is therefore important to understand and suppress the risk of steam explosions. The present study is concerned with mechanism of steam explosion on effect of coolant composition, i.e., to investigate how seawater impacts steam explosion energetics. For this purpose, a set of preliminary experiments were performed on spontaneous steam explosion by delivering a single molten tin droplet into a cold water pool at different levels of salinity on MISTEE facility. This paper presents the comparative results of the experimental data, including the influences of the salinity on probability of spontaneous explosion occurrence, explosion depth underwater and available thermal energy of droplet for explosion, as well as fragmentation (particle size distribution of debris % by mass). As the reference of the comparisons, the steam explosion characteristics from experiments in deionized water were employed. We experimentally observed that probability of spontaneous explosion occurrence increased in seawater, and more thermal energy of droplet was available for explosion when a droplet was self-triggered. The seawater at high salinity (35.16 g/kg) appeared remarkable enhancement on fragmentation. More experimental data are still needed to reveal more details and to develop a model for better understanding and prediction for the effects. The present data was helpful for prudential assessment on the seawater effects when it was employed as ultimate emergency cooling if NPPs located on sea coasts encounter Fukushima-like accidents.
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| 38. |
- Guo, Qiang, et al.
(författare)
-
Oxidation of molten zirconium-containing droplet in water
- 2024
-
Ingår i: Progress in nuclear energy (New series). - : Elsevier BV. - 0149-1970 .- 1878-4224. ; 175
-
Tidskriftsartikel (refereegranskat)abstract
- During a severe accident in light water reactors, the molten reactor core (corium) falls into a water pool in the form of a jet. Complex interactions may occur between the melt and coolant known as molten fuel-coolant interactions (FCI), including energetic coolant evaporation and metallic melt (e.g., Zr and Fe) oxidation. This may further lead to steam and hydrogen explosions, which are both substantial safety risks for nuclear power plants. The heat of reaction and hydrogen production during oxidation can influence the progress and severity of the accidents. For example, the reaction heat may prolong the liquid state of corium, potentially leading to highintensity explosions, whereas the generated hydrogen can create a combustible atmosphere, increasing the risk of hydrogen explosion. Therefore, this study evaluates the hydrogen production and oxidation degree of molten metallic droplets falling into a water pool to improve the FCI models for the risk evaluation of severe accident safety. The MISTEE-OX facility at KTH, which has been primarily built to study steam explosions is modified to investigate oxidation during FCI and provide experimental data on the oxidation behaviour of metallic droplets (Zr/Fe) quenched in a subcooled water pool. The dynamics of the falling droplets and generated bubbles are recorded using a high-speed camera, and the total volume of the bubbles is measured using a graduated cylinder. This study presents preliminary experimental results of the oxidation between Zr/Fe droplets and water, as well as recent improvements in measurement methods and facility upgrades. Our research findings are useful to enhance the knowledge of the oxidation process in FCI phenomena and validate the related mechanistic models in FCI codes.
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| 39. |
- Guo, S., et al.
(författare)
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Evidence for pseudospin-chiral quartet bands in the presence of octupole correlations
- 2020
-
Ingår i: Physics Letters B. - : ELSEVIER. - 0370-2693 .- 1873-2445. ; 807
-
Tidskriftsartikel (refereegranskat)abstract
- Three nearly degenerate pairs of doublet bands are identified in Ba-131. Two of them, with positive-parity, are interpreted as pseudospin-chiral quartet bands. This is the first time that a complete set of chiral doublet bands built on the pseudospin partners pi(d(5/2), g(7/2)) is observed. The chiral bands with opposite parity built on 3-quasiparticle configurations are directly connected by many E1 transitions, without involving an intermediary non-chiral configuration. The observed band structures in Ba-131 have been investigated by using the reflection-asymmetric particle rotor model. The energies and the electromagnetic transition ratios of the three pairs of doublet bands observed in Ba-131 are reproduced and they are interpreted as chiral doublet bands with three-quasiparticle configurations. It is the first time that multiple chiral bands are observed in the presence of enhanced octupole correlations and pseudospin symmetry.
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| 40. |
- Guo, Xiao-Hua, et al.
(författare)
-
Advanced glycation end products induce actin rearrangement and subsequent hyperpermeability of endothelial cells
- 2006
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Ingår i: APMIS : acta pathologica, microbiologica, et immunologica Scandinavica. - : Wiley. - 1600-0463 .- 0903-4641. ; 114:12, s. 874-883
-
Tidskriftsartikel (refereegranskat)abstract
- This study aimed to determine the effects of advanced glycation end products (AGEs) on endothelial cytoskeleton morphology and permeability, and to detect the underlying signaling mechanisms involved in these responses. Cultured endothelial cells (ECs) were exposed to AGE-modified human serum albumin (AGE-HSA), and EC cytoskeletal changes were evaluated by observing fluorescence of F-actin following ligation with labeled antibodies. Endothelial permeability was detected by measuring the flux of TRITC-albumin across the EC monolayers. To explore the signaling pathways behind AGE-induced EC alteration, ECs were treated with either soluble anti-AGE receptor (RAGE) IgG, or the MAPK inhibitors PD98059 and SB203580 before AGE-HSA administration. To further elucidate possible involvement of the ERK and p38 pathways in AGE-induced EC changes, adenovirus-carried recombinant constitutive dominant-negative forms of upstream ERK and p38 kinases, namely MEK1(A) and MKK6b(A), were pre-infected into ECs 24 h prior to AGE-HSA exposure. AGE-HSA induced actin cytoskeleton rearrangement, as well as EC hyperpermeability, in a dose and time-dependent manner. The effects were attenuated in cells pretreated with anti-RAGE IgG, PD98059 or SB203580, respectively. EC pre-infection with MEK1(A) and MKK6b(A) also alleviated the effect of AGEs. Furthermore, adenovirus-mediated administration of activated forms of either MEK1 or MKK6b alone induced rearrangement of F-actin and hyperpermeability. The results indicate that ERK and p38 MAPK play important roles in the mediation of AGE-induced EC barrier dysfunction associated with morphological changes of the F-actin.
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| 41. |
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| 42. |
- Han, Zixuan, et al.
(författare)
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Evaluating the large-scale hydrological cycle response within the Pliocene Model Intercomparison Project Phase 2 (PlioMIP2) ensemble
- 2021
-
Ingår i: Climate of the Past. - : Copernicus GmbH. - 1814-9324 .- 1814-9332. ; 17:6, s. 2537-2558
-
Tidskriftsartikel (refereegranskat)abstract
- The mid-Pliocene (∼3 Ma) is one of the most recent warm periods with high CO2 concentrations in the atmosphere and resulting high temperatures, and it is often cited as an analog for near-term future climate change. Here, we apply a moisture budget analysis to investigate the response of the large-scale hydrological cycle at low latitudes within a 13-model ensemble from the Pliocene Model Intercomparison Project Phase 2 (PlioMIP2). The results show that increased atmospheric moisture content within the mid-Pliocene ensemble (due to the thermodynamic effect) results in wetter conditions over the deep tropics, i.e., the Pacific intertropical convergence zone (ITCZ) and the Maritime Continent, and drier conditions over the subtropics. Note that the dynamic effect plays a more important role than the thermodynamic effect in regional precipitation minus evaporation (PmE) changes (i.e., northward ITCZ shift and wetter northern Indian Ocean). The thermodynamic effect is offset to some extent by a dynamic effect involving a northward shift of the Hadley circulation that dries the deep tropics and moistens the subtropics in the Northern Hemisphere (i.e., the subtropical Pacific). From the perspective of Earth's energy budget, the enhanced southward cross-equatorial atmospheric transport (0.22 PW), induced by the hemispheric asymmetries of the atmospheric energy, favors an approximately 1∘ northward shift of the ITCZ. The shift of the ITCZ reorganizes atmospheric circulation, favoring a northward shift of the Hadley circulation. In addition, the Walker circulation consistently shifts westward within PlioMIP2 models, leading to wetter conditions over the northern Indian Ocean. The PlioMIP2 ensemble highlights that an imbalance of interhemispheric atmospheric energy during the mid-Pliocene could have led to changes in the dynamic effect, offsetting the thermodynamic effect and, hence, altering mid-Pliocene hydroclimate.
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| 43. |
- Hao, Qian, et al.
(författare)
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Organic blue carbon sequestration in vegetated coastal wetlands: Processes and influencing factors
- 2024
-
Ingår i: Earth-Science Reviews. - 0012-8252 .- 1872-6828. ; 255, s. 104853-104853
-
Tidskriftsartikel (refereegranskat)abstract
- Coastal wetlands play a vital role in carbon (C) sequestration, named ‘blue carbon’. The review aims to disentangle the processes and influencing factors, including elevated atmospheric CO2, global climate warming, sea level rise and anthropogenic activities. Firstly, we provided an overview of C processes, including input, output, and deposition, in coastal wetlands. We then summarized the impacts of different factors on C processes by modifying soil physicochemical properties, plant growth, vegetation type, and microbial community composition. Vegetation composition was a major contributor to C inputs, and C outputs was mainly controlled by microbial decomposition. Increased atmospheric CO2 concentration and associated climate warming often enhanced vegetation growth, while climate warming also promoted soil C decomposition. As a result, C storage could increase under mild warming conditions in the short-term, but decrease in the long-term as the severity of warming intensifies. Elevated salinity, caused by sea level rise, can be harmful to plant growth and inhibit organic C decomposition because of the reduced biomass and the weakened metabolic capacity of microorganisms. Most of human activities, such as reclamation, can lead to less C input and more C output, resulting in decreased C storage in coastal wetlands. Additionally, we also illustrate various coastal wetland restoration methods aimed at enhancing C sequestration, including legal frameworks, scientific theories, vegetation management, hydrological restoration, and other relevant constructions. Vegetation management could benefit plant growth and enhance C input effectively, and hydrological restoration can maintain the harmonious development of coastal wetland ecosystems. Other constructions, including breakwater, spillway, and dredged material, could protect coastal wetlands, especially facing sea level rise. This review offers valuable theoretical support and scientific references for the sustainable development and management of coastal wetlands in a changing climate.
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| 44. |
- Haywood, Alan M., et al.
(författare)
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The Pliocene Model Intercomparison Project Phase 2 : large-scale climate features and climate sensitivity
- 2020
-
Ingår i: Climate of the Past. - : Copernicus GmbH. - 1814-9324 .- 1814-9332. ; 16:6, s. 2095-2123
-
Tidskriftsartikel (refereegranskat)abstract
- The Pliocene epoch has great potential to improve our understanding of the long-term climatic and environmental consequences of an atmospheric CO2 concentration near similar to 400 parts per million by volume. Here we present the large-scale features of Pliocene climate as simulated by a new ensemble of climate models of varying complexity and spatial resolution based on new reconstructions of boundary conditions (the Pliocene Model Intercomparison Project Phase 2; PlioMIP2). As a global annual average, modelled surface air temperatures increase by between 1.7 and 5.2 degrees C relative to the pre-industrial era with a multi-model mean value of 3.2 degrees C. Annual mean total precipitation rates increase by 7 % (range: 2 %-13 %). On average, surface air temperature (SAT) increases by 4.3 degrees C over land and 2.8 degrees C over the oceans. There is a clear pattern of polar amplification with warming polewards of 60 degrees N and 60 degrees S exceeding the global mean warming by a factor of 2.3. In the Atlantic and Pacific oceans, meridional temperature gradients are reduced, while tropical zonal gradients remain largely unchanged. There is a statistically significant relationship between a model's climate response associated with a doubling in CO2 (equilibrium climate sensitivity; ECS) and its simulated Pliocene surface temperature response. The mean ensemble Earth system response to a doubling of CO2 (including ice sheet feedbacks) is 67 % greater than ECS; this is larger than the increase of 47 % obtained from the PlioMIP1 ensemble. Proxy-derived estimates of Pliocene sea surface temperatures are used to assess model estimates of ECS and give an ECS range of 2.6-4.8 degrees C. This result is in general accord with the ECS range presented by previous Intergovernmental Panel on Climate Change (IPCC) Assessment Reports.
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| 45. |
- Hou, Jianshen, et al.
(författare)
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Rewiring carbon flux in Escherichia coli using a bifunctional molecular switch
- 2020
-
Ingår i: Metabolic Engineering. - : Elsevier BV. - 1096-7176 .- 1096-7184. ; 61, s. 47-57
-
Tidskriftsartikel (refereegranskat)abstract
- The unbalanced distribution of carbon flux in microbial cell factories can lead to inefficient production and poor cell growth. Uncoupling cell growth and chemical synthesis can therefore improve microbial cell factory efficiency. Such uncoupling, which requires precise manipulation of carbon fluxes, can be achieved by up-regulating or down-regulating the expression of enzymes of various pathways. In this study, a dynamic turn-off switch (dTFS) and a dynamic turn-on switch (dTNS) were constructed using growth phase-dependent promoters and degrons. By combining the dTFS and dTNS, a bifunctional molecular switch that could orthogonally regulate two target proteins was introduced. This bifunctional molecular switch was used to uncouple cell growth from shikimic acid and D-glucaric acid synthesis, resulting in the production of 14.33 g/L shikimic acid and the highest reported productivity of D-glucaric acid (0.0325 g/L/h) in Escherichia coli MG1655. This proved that the bifunctional molecular switch could rewire carbon fluxes by controlling target protein abundance.
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| 46. |
- Huang, Hongyun, et al.
(författare)
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Clinical Cell Therapy Guidelines for Neurorestoration (IANR/CANR 2017)
- 2018
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Ingår i: Cell Transplantation. - : SAGE Publications. - 0963-6897 .- 1555-3892. ; 27:2, s. 310-324
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Forskningsöversikt (refereegranskat)abstract
- Cell therapy has been shown to be a key clinical therapeutic option for central nervous system diseases or damage. Standardization of clinical cell therapy procedures is an important task for professional associations devoted to cell therapy. The Chinese Branch of the International Association of Neurorestoratology (IANR) completed the first set of guidelines governing the clinical application of neurorestoration in 2011. The IANR and the Chinese Association of Neurorestoratology (CANR) collaborated to propose the current version "Clinical Cell Therapy Guidelines for Neurorestoration (IANR/CANR 2017)". The IANR council board members and CANR committee members approved this proposal on September 1, 2016, and recommend it to clinical practitioners of cellular therapy. These guidelines include items of cell type nomenclature, cell quality control, minimal suggested cell doses, patient-informed consent, indications for undergoing cell therapy, contraindications for undergoing cell therapy, documentation of procedure and therapy, safety evaluation, efficacy evaluation, policy of repeated treatments, do not charge patients for unproven therapies, basic principles of cell therapy, and publishing responsibility.
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| 47. |
- Jenniskens, Peter, et al.
(författare)
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The Creston, California, meteorite fall and the origin of L chondrites
- 2019
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Ingår i: Meteoritics and Planetary Science. - : John Wiley & Sons. - 1086-9379 .- 1945-5100. ; 54:4, s. 699-720
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Tidskriftsartikel (refereegranskat)abstract
- It has been proposed that all L chondrites resulted from an ongoing collisional cascade of fragments that originated from the formation of the ~500 Ma old asteroid family Gefion, located near the 5:2 mean‐motion resonance with Jupiter in the middle Main Belt. If so, L chondrite pre‐atmospheric orbits should be distributed as expected for that source region. Here, we present contradictory results from the orbit and collisional history of the October 24, 2015, L6 ordinary chondrite fall at Creston, CA (here reclassified to L5/6). Creston's short 1.30 ± 0.02 AU semimajor axis orbit would imply a long dynamical evolution if it originated from the middle Main Belt. Indeed, Creston has a high cosmic ray exposure age of 40–50 Ma. However, Creston's small meteoroid size and low 4.23 ± 0.07° inclination indicate a short dynamical lifetime against collisions. This suggests, instead, that Creston originated most likely in the inner asteroid belt and was delivered via the ν6 resonance. The U‐Pb systematics of Creston apatite reveals a Pb‐Pb age of 4,497.1 ± 3.7 Ma, and an upper intercept U‐Pb age of 4,496.7 ± 5.8 Ma (2σ), circa 70 Ma after formation of CAI, as found for other L chondrites. The K‐Ar (age ~4.3 Ga) and U,Th‐He (age ~1 Ga) chronometers were not reset at ~500 Ma, while the lower intercept U‐Pb age is poorly defined as 770 ± 320 Ma. So far, the three known L chondrites that impacted on orbits with semimajor axes a <2.0 AU all have high (>3 Ga) K‐Ar ages. This argues for a source of some of our L chondrites in the inner Main Belt. Not all L chondrites originate in a continuous population of Gefion family debris stretching across the 3:1 mean‐motion resonance.
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| 48. |
- Jenniskens, Peter, et al.
(författare)
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The impact and recovery of asteroid 2018 LA
- 2021
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Ingår i: Meteoritics and Planetary Science. - : John Wiley & Sons. - 1086-9379 .- 1945-5100. ; 56:4, s. 844-893
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Tidskriftsartikel (refereegranskat)abstract
- The June 2, 2018 impact of asteroid 2018 LA over Botswana is only the second asteroid detected in space prior to impacting over land. Here, we report on the successful recovery of meteorites. Additional astrometric data refine the approach orbit and define the spin period and shape of the asteroid. Video observations of the fireball constrain the asteroid's position in its orbit and were used to triangulate the location of the fireball's main flare over the Central Kalahari Game Reserve. Twenty‐three meteorites were recovered. A consortium study of eight of these classifies Motopi Pan as an HED polymict breccia derived from howardite, cumulate and basaltic eucrite, and diogenite lithologies. Before impact, 2018 LA was a solid rock of ~156 cm diameter with high bulk density ~2.85 g cm−3, a relatively low albedo pV ~ 0.25, no significant opposition effect on the asteroid brightness, and an impact kinetic energy of ~0.2 kt. The orbit of 2018 LA is consistent with an origin at Vesta (or its Vestoids) and delivery into an Earth‐impacting orbit via the ν6 resonance. The impact that ejected 2018 LA in an orbit toward Earth occurred 22.8 ± 3.8 Ma ago. Zircons record a concordant U‐Pb age of 4563 ± 11 Ma and a consistent 207Pb/206Pb age of 4563 ± 6 Ma. A much younger Pb‐Pb phosphate resetting age of 4234 ± 41 Ma was found. From this impact chronology, we discuss what is the possible source crater of Motopi Pan and the age of Vesta's Veneneia impact basin.
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| 49. |
- Kang, Nai-xin, et al.
(författare)
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Anemoside B4 inhibits enterovirus 71 propagation in mice through upregulating 14-3-3 expression and type I interferon responses
- 2022
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Ingår i: Acta Pharmacologica Sinica. - : Springer Nature. - 1671-4083 .- 1745-7254. ; 43, s. 977-991
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Tidskriftsartikel (refereegranskat)abstract
- Enterovirus 71 (EV71) is the major pathogens of human hand, foot, and mouth disease (HFMD). EV71 efficiently escapes innate immunity responses of the host to cause infection. At present, no effective antiviral drugs for EV71 are available. Anemoside B4 (B4) is a natural saponin isolated from the roots of Pulsatilla chinensis (Bunge) Regel. P. chinensis extracts that shows a wide variety of biological activities. In this study, we investigated the antiviral activities of B4 against EV71 both in cell culture and in suckling mice. We showed that B4 (12.5-200 mu M) dose dependently increased the viability of EV71-infected RD cells with an IC50 value of 24.95 +/- 0.05 mu M against EV71. The antiviral activity of B4 was associated with enhanced interferon (IFN)-beta response, since knockdown of IFN-beta abolished its antiviral activity. We also confirmed that the enhanced IFN response was mediated via activation of retinoic acid-inducible gene I (RIG-I) like receptors (RLRs) pathway, and it was executed by upregulation of 14-3-3 protein, which disrupted the interaction between yes-associated protein (YAP) and interferon regulatory factor 3 (IRF3). By using amino acids in cell culture (SILAC)-based proteomics profiling, we identified the Hippo pathway as the top-ranking functional cluster in B4-treated EV71-infected cells. In vivo experiments were conducted in suckling mice (2-day-old) infected with EV71 and subsequently B4 (200 mg center dot kg(-1) center dot d(-1), i.p.) was administered for 16 days. We showed that B4 administration effectively suppressed EV71 replication and improved muscle inflammation and limb activity. Meanwhile, B4 administration regulated the expressions of HFMD biomarkers IL-10 and IFN-gamma, attenuating complications of EV71 infection. Collectively, our results suggest that B4 could enhance the antiviral effect of IFN-beta by orchestrating Hippo and RLRs pathway, and B4 would be a potential lead compound for developing an anti-EV71 drug.
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| 50. |
- Kristan, Matej, et al.
(författare)
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The Sixth Visual Object Tracking VOT2018 Challenge Results
- 2019
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Ingår i: Computer Vision – ECCV 2018 Workshops. - Cham : Springer Publishing Company. - 9783030110086 - 9783030110093 ; , s. 3-53
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Konferensbidrag (refereegranskat)abstract
- The Visual Object Tracking challenge VOT2018 is the sixth annual tracker benchmarking activity organized by the VOT initiative. Results of over eighty trackers are presented; many are state-of-the-art trackers published at major computer vision conferences or in journals in the recent years. The evaluation included the standard VOT and other popular methodologies for short-term tracking analysis and a “real-time” experiment simulating a situation where a tracker processes images as if provided by a continuously running sensor. A long-term tracking subchallenge has been introduced to the set of standard VOT sub-challenges. The new subchallenge focuses on long-term tracking properties, namely coping with target disappearance and reappearance. A new dataset has been compiled and a performance evaluation methodology that focuses on long-term tracking capabilities has been adopted. The VOT toolkit has been updated to support both standard short-term and the new long-term tracking subchallenges. Performance of the tested trackers typically by far exceeds standard baselines. The source code for most of the trackers is publicly available from the VOT page. The dataset, the evaluation kit and the results are publicly available at the challenge website (http://votchallenge.net).
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