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Sökning: WFRF:(Zhou Xu Zhi)

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1.
  • Beal, Jacob, et al. (författare)
  • Robust estimation of bacterial cell count from optical density
  • 2020
  • Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
  • 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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3.
  • 2019
  • Tidskriftsartikel (refereegranskat)
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4.
  • Klionsky, Daniel J., et al. (författare)
  • Guidelines for the use and interpretation of assays for monitoring autophagy
  • 2012
  • Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
  • 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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5.
  • Kristan, Matej, et al. (författare)
  • The Sixth Visual Object Tracking VOT2018 Challenge Results
  • 2019
  • Ingår i: Computer Vision – ECCV 2018 Workshops. - Cham : Springer Publishing Company. - 9783030110086 - 9783030110093 ; , s. 3-53
  • 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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6.
  • Pecunia, Vincenzo, et al. (författare)
  • Roadmap on energy harvesting materials
  • 2023
  • Ingår i: Journal of Physics. - : IOP Publishing. - 2515-7639. ; 6:4
  • Tidskriftsartikel (refereegranskat)abstract
    • Ambient energy harvesting has great potential to contribute to sustainable development and address growing environmental challenges. Converting waste energy from energy-intensive processes and systems (e.g. combustion engines and furnaces) is crucial to reducing their environmental impact and achieving net-zero emissions. Compact energy harvesters will also be key to powering the exponentially growing smart devices ecosystem that is part of the Internet of Things, thus enabling futuristic applications that can improve our quality of life (e.g. smart homes, smart cities, smart manufacturing, and smart healthcare). To achieve these goals, innovative materials are needed to efficiently convert ambient energy into electricity through various physical mechanisms, such as the photovoltaic effect, thermoelectricity, piezoelectricity, triboelectricity, and radiofrequency wireless power transfer. By bringing together the perspectives of experts in various types of energy harvesting materials, this Roadmap provides extensive insights into recent advances and present challenges in the field. Additionally, the Roadmap analyses the key performance metrics of these technologies in relation to their ultimate energy conversion limits. Building on these insights, the Roadmap outlines promising directions for future research to fully harness the potential of energy harvesting materials for green energy anytime, anywhere.
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7.
  • Xu, Qin, et al. (författare)
  • Loss of TET reprograms Wnt signaling through impaired demethylation to promote lung cancer development
  • 2022
  • Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences (PNAS). - 0027-8424 .- 1091-6490. ; 119:6
  • Tidskriftsartikel (refereegranskat)abstract
    • Oncogenic imbalance of DNA methylation is well recognized in cancer development. The ten-eleven translocation (TET) family of dioxygenases, which facilitates DNA demethylation, is frequently dysregulated in cancers. How such dysregulation contributes to tumorigenesis remains poorly understood, especially in solid tumors which present infrequent mutational incidence of TET genes. Here, we identify loss-of-function mutations of TET in 7.4% of human lung adenocarcinoma (LUAD), which frequently co-occur with oncogenic KRAS mutations, and this co-occurrence is predictive of poor survival in LUAD patients. Using an autochthonous mouse model of KrasG12D-driven LUAD, we show that individual or combinational loss of Tet genes markedly promotes tumor development. In this Kras-mutant and Tet-deficient model, the premalignant lung epithelium undergoes neoplastic reprogramming of DNA methylation and transcription, with a particular impact on Wnt signaling. Among the Wnt-associated components that undergo reprogramming, multiple canonical Wnt antagonizing genes present impaired expression arising from elevated DNA methylation, triggering aberrant activation of Wnt signaling. These impairments can be largely reversed upon the restoration of TET activity. Correspondingly, genetic depletion of beta-catenin, the transcriptional effector of Wnt signaling, substantially reverts the malignant progression of Tet-deficient LUAD. These findings reveal TET enzymes as critical epigenetic barriers against lung tumorigenesis and highlight the therapeutic vulnerability of TET-mutant lung cancer through targetingWnt signaling.
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8.
  • Blanton, Michael R., et al. (författare)
  • Sloan Digital Sky Survey IV : Mapping the Milky Way, Nearby Galaxies, and the Distant Universe
  • 2017
  • Ingår i: Astronomical Journal. - : IOP Publishing Ltd. - 0004-6256 .- 1538-3881. ; 154:1
  • Tidskriftsartikel (refereegranskat)abstract
    • We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and. high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median z similar to 0.03). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between z similar to 0.6 and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs. and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the. Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July.
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9.
  • Hu, Li-Peng, et al. (författare)
  • Terbinafine prevents colorectal cancer growth by inducing dNTP starvation and reducing immune suppression
  • 2022
  • Ingår i: Molecular Therapy. - : Elsevier BV. - 1525-0024 .- 1525-0016. ; 30:10, s. 3284-3299
  • Tidskriftsartikel (refereegranskat)abstract
    • Existing evidence indicates that gut fungal dysbiosis might play a key role in the pathogenesis of colorectal cancer (CRC). We sought to explore whether reversing the fungal dysbiosis by terbinafine, an approved antifungal drug, might inhibit the development of CRC. A population-based study from Sweden identified a total of 185 patients who received terbinafine after their CRC diagnosis and found that they had a decreased risk of death (hazard ratio=0.50) and metastasis (hazard ratio=0.44) compared with patients without terbinafine administration. In multiple mouse models of CRC, administration of terbinafine decreased the fungal load, the fungus-induced myeloid-derived suppressor cell (MDSC) expansion, and the tumor burden. Fecal microbiota transplantation from mice without terbinafine treatment reversed MDSC infiltration and partially restored tumor proliferation. Mechanistically, terbinafine directly impaired tumor cell proliferation by reducing the ratio of nicotinamide adenine dinucleotide phosphate (NADP+) to reduced form of nicotinamide adenine dinucleotide phosphate (NADPH), suppressing the activity of glucose-6-phosphate dehydrogenase (G6PD), resulting in nucleotide synthesis disruption, deoxyribonucleotide (dNTP) starvation and cell cycle arrest. Collectively, terbinafine can inhibit CRC by reversing fungal dysbiosis, suppressing tumor cell proliferation, inhibiting fungus-induced MDSC infiltration, and restoring antitumor immune response.
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10.
  • Jin, Ying-Hui, et al. (författare)
  • Chemoprophylaxis, diagnosis, treatments, and discharge management of COVID-19 : An evidence-based clinical practice guideline (updated version)
  • 2020
  • Ingår i: Military Medical Research. - : Springer Science and Business Media LLC. - 2054-9369. ; 7:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of a rapidly spreading illness, coronavirus disease 2019 (COVID-19), affecting more than seventeen million people around the world. Diagnosis and treatment guidelines for clinicians caring for patients are needed. In the early stage, we have issued "A rapid advice guideline for the diagnosis and treatment of 2019 novel coronavirus (2019-nCoV) infected pneumonia (standard version)"; now there are many direct evidences emerged and may change some of previous recommendations and it is ripe for develop an evidence-based guideline. We formed a working group of clinical experts and methodologists. The steering group members proposed 29 questions that are relevant to the management of COVID-19 covering the following areas: chemoprophylaxis, diagnosis, treatments, and discharge management. We searched the literature for direct evidence on the management of COVID-19, and assessed its certainty generated recommendations using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. Recommendations were either strong or weak, or in the form of ungraded consensus-based statement. Finally, we issued 34 statements. Among them, 6 were strong recommendations for, 14 were weak recommendations for, 3 were weak recommendations against and 11 were ungraded consensus-based statement. They covered topics of chemoprophylaxis (including agents and Traditional Chinese Medicine (TCM) agents), diagnosis (including clinical manifestations, reverse transcription-polymerase chain reaction (RT-PCR), respiratory tract specimens, IgM and IgG antibody tests, chest computed tomography, chest x-ray, and CT features of asymptomatic infections), treatments (including lopinavir-ritonavir, umifenovir, favipiravir, interferon, remdesivir, combination of antiviral drugs, hydroxychloroquine/chloroquine, interleukin-6 inhibitors, interleukin-1 inhibitors, glucocorticoid, qingfei paidu decoction, lianhua qingwen granules/capsules, convalescent plasma, lung transplantation, invasive or noninvasive ventilation, and extracorporeal membrane oxygenation (ECMO)), and discharge management (including discharge criteria and management plan in patients whose RT-PCR retesting shows SARS-CoV-2 positive after discharge). We also created two figures of these recommendations for the implementation purpose. We hope these recommendations can help support healthcare workers caring for COVID-19 patients.
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11.
  • Li, Xing-Yu, et al. (författare)
  • Comparative Study of Dayside Pulsating Auroras Induced by Ultralow-Frequency Waves
  • 2023
  • Ingår i: Universe. - : MDPI AG. - 2218-1997. ; 9:6
  • Tidskriftsartikel (refereegranskat)abstract
    • Pulsating auroras are usually observed with ultralow-frequency (ULF) waves in the Pc 3-5 band (period 10-600 s). These auroras are thought to result from interactions between energetic electrons and chorus waves, but their relationship with ULF waves remains an open question. In this study, we investigated this question by conducting a comparative study on two ULF wave events with pulsating auroras observed near the magnetic footprints. Conjugate observations from the Magnetospheric Multiscale mission and the Chinese Yellow River Station were used. In both events, lower-band chorus waves were observed, which were suggested to be connected with the auroral pulsations by wavelet analysis. The intensity of these waves oscillates at the period of the ULF waves, but the physics laid behind them differs by events. During the event of 22 January 2019, compressional ULF waves changed the threshold for the whistler anisotropy instability periodically, affecting the emission of chorus waves. In the event on 10 January 2016, poloidal ULF waves modulated the chorus wave generation by regulating electron temperature anisotropy through drift resonance. ULF waves in these events may originate from perturbations in the solar wind. We highlight the role of ULF waves in the solar wind-magnetosphere-ionosphere coupling, which requires further study.
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12.
  • Li, Xing Yu, et al. (författare)
  • Ion Acceleration and Corresponding Bounce Echoes Induced by Electric Field Impulses: MMS Observations
  • 2024
  • Ingår i: Journal of Geophysical Research - Space Physics. - : American Geophysical Union (AGU). - 2169-9380 .- 2169-9402. ; 129:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Dayside magnetosphere interactions are essential for energy and momentum transport between the solar wind and the magnetosphere. In this study, we investigate a new phenomenon within this regime. Sudden enhancements of ion fluxes followed by repeating dropouts and recoveries were observed by Magnetospheric Multiscale on 5 November 2016, which is the very end of the recovery phase from a moderate geomagnetic storm. These repetitive flux variations display energy-dispersive characteristics with periods relevant to ion bounce motion, suggesting they are corresponding echoes. Alongside the flux variations, bipolar electric field impulses originating from external sources were detected. We traced the source region of the initial injection and found it is located near the spacecraft's position. To elucidate the underlying physics, a test-particle simulation is conducted. The results reveal that radial transport resulting from impulse-induced acceleration can give rise to these echoes. Observations demonstrate dayside magnetosphere interactions are more common than we previously considered, which warrants further research.
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13.
  • Li, Xing-Yu, et al. (författare)
  • Off-Equatorial Minima Effects on ULF Wave-Ion Interaction in the Dayside Outer Magnetosphere
  • 2021
  • Ingår i: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 48:18
  • Tidskriftsartikel (refereegranskat)abstract
    • The ultra-low frequency wave-particle drift-bounce resonance in the inner magnetosphere has been studied in detail, due to its important role in particle energization. However, it remains an open question how drift-bounce resonance manifests in the dayside outer magnetosphere, where particles' orbits show bifurcations because of off-equatorial magnetic field minima. In this study, we investigate this question, by analyzing Magnetospheric Multiscale observations of the January 20, 2017 event. A test-particle simulation is conducted to help us understand the observations. The observed pitch angle-time spectrograms show "pawtrack-like" structures. We find there are more than two resonant pitch angles at fixed energy, since off-equatorial minima change the relationship between the bounce (drift) frequency and pitch angle from unimodal function to trimodal function. These results reveal a new drift-bounce acceleration mechanism in the dayside outer magnetosphere, which potentially affects the efficiency of particle energization during geomagnetic activities like geomagnetic storms.
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14.
  • Li, Xing-Yu, et al. (författare)
  • ULF Wave-Induced Ion Pitch Angle Evolution in the Dayside Outer Magnetosphere
  • 2022
  • Ingår i: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 49:8
  • Tidskriftsartikel (refereegranskat)abstract
    • Drift-bounce resonance between ultralow frequency (ULF) waves and ions is essential for ion energization in the magnetosphere. Here, we present the first comprehensive study of drift-bounce resonance in the dayside outer magnetosphere, where off-equatorial magnetic field minima would strongly distort ions' bounce and drift motion. A generalized theory is proposed, in which the effects of off-equatorial minima, time-evolving fields and ion bounce motion are taken into account. In consequence of these effects, ion pitch angle distributions undergo dramatic changes. In the presence of off-equatorial minima, the time-of-flight effect of ion bounce motion forms latitude-dependent dispersions besides "paw-track shaped" structures, while evolving wave fields cause time-dependent phase shifts in "paw-tracks." All the predicted signatures have been confirmed by 5 years of Magnetospheric Multiscale spacecraft data and numerical simulations. These results allow us to better understand the interactions between ULF waves and thermal ion species in global magnetospheric dynamics.
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15.
  • Wang, Shan, et al. (författare)
  • Electrostatic Waves Around a Magnetopause Reconnection Secondary Electron Diffusion Region Modulated by Whistler and Lower-Hybrid Waves
  • 2023
  • Ingår i: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 50:18
  • Tidskriftsartikel (refereegranskat)abstract
    • We investigate electrostatic waves in a magnetopause reconnection event around a secondary electron diffusion region. Near the current sheet mid-plane, parallel electron beam-mode waves are modulated by whistler waves. We conclude that the anisotropy of energized electrons in the reconnection exhaust excites whistler waves, which produce spatially modulated electron beams through nonlinear Landau resonance, and these beams excite beam-mode electrostatic waves. In the separatrix region, parallel propagating electrostatic waves associated with field-aligned electron beams and perpendicular propagating electron cyclotron harmonic waves with loss cone distributions exhibit modulation frequencies in the lower-hybrid wave (LHW) frequency range. We infer that LHWs scatter electrons to produce beams and alter loss cones to modulate electrostatic waves. The results advance our understanding about the regimes and mechanisms of electrostatic waves in reconnection, with an emphasis on their coupling with lower-frequency electromagnetic waves. Magnetic reconnection is an important energy dissipation process at the Earth's dayside magnetopause. In its central region, plasmas deviate from the thermal equilibrium and form structured distribution functions, which excite plasma waves. We investigate high-frequency electrostatic waves in an event, where the waves are associated with electron beam-plasma interaction or anisotropy of distribution functions. We find that electrostatic waves are driven and modulated by lower-frequency waves, as the latter alters the particle distribution functions. The results help us understand how various processes couple with each other to achieve the energy dissipation. Parallel electron beam-mode waves are modulated by whistler near the current sheet mid-plane, by driving beams through Landau resonanceElectron beam-mode and cyclotron waves are modulated by lower-hybrid waves near separatrices, with beam and loss cone distributions
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16.
  • Xie, Zi Kang, et al. (författare)
  • Electron scale coherent structure as micro accelerator in the Earth's magnetosheath
  • 2024
  • Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 15:1, s. 886-
  • Tidskriftsartikel (refereegranskat)abstract
    • Turbulent energy dissipation is a fundamental process in plasma physics that has not been settled. It is generally believed that the turbulent energy is dissipated at electron scales leading to electron energization in magnetized plasmas. Here, we propose a micro accelerator which could transform electrons from isotropic distribution to trapped, and then to stream (Strahl) distribution. From the MMS observations of an electron-scale coherent structure in the dayside magnetosheath, we identify an electron flux enhancement region in this structure collocated with an increase of magnetic field strength, which is also closely associated with a non-zero parallel electric field. We propose a trapping model considering a field-aligned electric potential together with the mirror force. The results are consistent with the observed electron fluxes from ~50 eV to ~200 eV. It further demonstrates that bidirectional electron jets can be formed by the hourglass-like magnetic configuration of the structure.
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17.
  • Zhou, Xu-Zhi, et al. (författare)
  • On the Origin of Perpendicular Ion Anisotropy Inside Dipolarizing Flux Bundles
  • 2019
  • Ingår i: Journal of Geophysical Research - Space Physics. - 2169-9380 .- 2169-9402. ; 124:6, s. 4009-4021
  • Tidskriftsartikel (refereegranskat)abstract
    • Perpendicular anisotropy of suprathermal ions, observed inside some of the dipolarizing flux bundles (DFBs) in the magnetotail plasma sheet, have been attributed to successive, betatron-type accelerations during the DFB entry of ambient ions. It has been unclear, however, where and how these ions enter the DFBs. The proposed locations include the DFB flanks where cross-tail drifting ions are picked up, and the DFB leading edge with sharp magnetic field gradient (the dipolarization front, DF). Here we examine the latter scenario, based on a simplistic, test particle approach, to predict the preferred conditions for the appearance of the DFB ion anisotropy. Our model predicts that the ion anisotropy would be stronger at locations closer to the neutral sheet and would appear preferentially in the DFB dawnside and central sectors rather than the duskside sector. We also predict that the ion anisotropy would more likely be observed in DFBs with higher propagation speeds. These properties can be understood in our model by the dawnward drift of ions during their DF penetration (attributed to the large magnetic gradient). To examine these predictions, we carry out a statistical survey based on observations from the THEMIS (Time History of Events and Macroscale Interactions during Substorms) mission, to show a clear dependence of the ion anisotropy on spacecraft location and the DFB propagation speed. These findings, therefore, are consistent with the scenario that the perpendicular ion anisotropy originates from the ion acceleration and penetration across sharp DFs.
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18.
  • Chen, Mei-Qin, et al. (författare)
  • Arabidopsis NMD3 is required for nuclear export of 60S ribosomal subunits and affects secondary cell wall thickening
  • 2012
  • Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:4, s. 35904-35904
  • Tidskriftsartikel (refereegranskat)abstract
    • NMD3 is required for nuclear export of the 60S ribosomal subunit in yeast and vertebrate cells, but no corresponding function of NMD3 has been reported in plants. Here we report that Arabidopsis thaliana NMD3 (AtNMD3) showed a similar function in the nuclear export of the 60S ribosomal subunit. Interference with AtNMD3 function by overexpressing a truncated dominant negative form of the protein lacking the nuclear export signal sequence caused retainment of the 60S ribosomal subunits in the nuclei. More interestingly, the transgenic Arabidopsis with dominant negative interference of AtNMD3 function showed a striking failure of secondary cell wall thickening, consistent with the altered expression of related genes and composition of cell wall components. Observation of a significant decrease of rough endoplasmic reticulum (RER) in the differentiating interfascicular fiber cells of the transgenic plant stems suggested a link between the defective nuclear export of 60S ribosomal subunits and the abnormal formation of the secondary cell wall. These findings not only clarified the evolutionary conservation of NMD3 functions in the nuclear export of 60S ribosomal subunits in yeast, animals and plants, but also revealed a new facet of the regulatory mechanism underlying secondary cell wall thickening in Arabidopsis. This new facet is that the nuclear export of 60S ribosomal subunits and the formation of RER may play regulatory roles in coordinating protein synthesis in cytoplasm and transcription in nuclei.
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19.
  • Gao, Yulong, et al. (författare)
  • The molecular gas resolved by ALMA in the low-metallicity merging dwarf galaxy Haro 11
  • 2022
  • Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 661
  • Tidskriftsartikel (refereegranskat)abstract
    • Context. The physical mechanisms driving starbursts and quenching in less massive (M* ≤ 1010 M⊙) galaxies are unclear. The merger is one of the inescapable processes referred to as both starburst and quenching in massive galaxies. However, the effects of the merger on star formation in dwarf galaxies and their evolution are still uncertain.Aims. We aim to explore how star formation in dwarf galaxies is both triggered and quenched by studying metal-poor gas-rich dwarf mergers based on multi-band observations at a spatial resolution of ∼460 pc.Methods. We use archival data of Atacama Large Millimetre Array (Band 3 and 8) and Very Large Telescope/Multi Unit Spectroscopic Explorer to map CO(J = 1–0), [CI](3P1–3P0), and Hα emission in one of the most extreme merging starburst dwarf galaxies, Haro 11.Results. We find the molecular gas is assembled around the central two star-forming regions (knots B and C). The molecular and ionized gas and stellar components show complex kinematics, indicating that the gas is probably at a combined stage of collision of clouds and feedback from star formation. The peak location and distribution of [CI](1–0) closely coincide with the CO(1–0) emission, meaning that it might trace the same molecular gas as CO in such a dwarf merger starburst galaxy. The enhancement of line ratios (∼0.5) of [CI]/CO around knot C is probably generated by the dissociation of CO molecules by cosmic rays and far-ultraviolet photons. Globally, Haro 11 and its star-forming regions share similar star formation efficiency (SFE) to the high-z starburst galaxies or the clumps in nearby ultraluminous infrared galaxies.Conclusions. Given the high SFE, the high specific star formation rate, small stellar mass, low metallicity, and deficient HI gas, Haro 11 could be an analog of a high-z dwarf starburst and the potential progenitor of the nearby less massive elliptical galaxies. The significantly smaller turbulent pressure and viral parameter is probably triggering the intense starbursts. We predict that Haro 11 will quench at M* ≤ 8.5  ×  109 M⊙.
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20.
  • Jia, Kai-Hua, et al. (författare)
  • Chromosome-scale assembly and evolution of the tetraploid Salvia splendens (Lamiaceae) genome
  • 2021
  • Ingår i: Horticulture Research. - : Oxford University Press (OUP). - 2052-7276 .- 2662-6810. ; 8:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Polyploidization plays a key role in plant evolution, but the forces driving the fate of homoeologs in polyploid genomes, i.e., paralogs resulting from a whole-genome duplication (WGD) event, remain to be elucidated. Here, we present a chromosome-scale genome assembly of tetraploid scarlet sage (Salvia splendens), one of the most diverse ornamental plants. We found evidence for three WGD events following an older WGD event shared by most eudicots (the γ event). A comprehensive, spatiotemporal, genome-wide analysis of homoeologs from the most recent WGD unveiled expression asymmetries, which could be associated with genomic rearrangements, transposable element proximity discrepancies, coding sequence variation, selection pressure, and transcription factor binding site differences. The observed differences between homoeologs may reflect the first step toward sub- and/or neofunctionalization. This assembly provides a powerful tool for understanding WGD and gene and genome evolution and is useful in developing functional genomics and genetic engineering strategies for scarlet sage and other Lamiaceae species.
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21.
  • Liu, Chun-Yan, et al. (författare)
  • Massively Parallel Aligned Poly(vinylidene fluoride) Nanofibrils in All-Organic Dielectric Polymer Composite Films for Electric Energy Storage
  • 2023
  • Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 56:4, s. 1481-1491
  • Tidskriftsartikel (refereegranskat)abstract
    • It is a formidable challenge to combine the perform-ance advantages of linear and nonlinear polymer dielectrics for developing all-organic film capacitors with high energy density and low loss. In this work, massively parallel aligned poly(vinylidene fluoride) (PVDF) nanofibrils were in situ fabricated for the first time in the polyethylene (PE) matrix via a multistage stretching technology involving hot stretching and solid-state stretching at an elevated temperature. The largely enhanced interfacial area of PVDF nanofibrils could effectively induce interfacial polarization, imparting PE composite films with a high dielectric constant of 4.50. More interestingly, the nanoconfinement effect of PVDF nanofibrils greatly restricted the migration of free electrons and impurity ions, and an impressive breakdown strength of 624 MV m-1 was obtained. As a result, the as-prepared PE/PVDF composite films exhibited an attractive discharged energy density of as high as 6.4 J cm-3, which was more than 10 times of the conventional counterparts, and outperformed the current linear dielectric polymers. The ingenious structure design of in situ nonlinear dielectric nanofibrils provides a promising approach to maximize the advantageous polarizations and minimize the disadvantageous polarizations in the linear and nonlinear polymer dielectric blends, achieving all-organic polymer dielectric composite films with high energy density and low loss.
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22.
  • Liu, Wei, et al. (författare)
  • Coherent dynamics of multi-spin V-B(-) center in hexagonal boron nitride
  • 2022
  • Ingår i: Nature Communications. - : Nature Portfolio. - 2041-1723. ; 13:1
  • 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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23.
  • Lu, Shen-ning, et al. (författare)
  • Application of an innovative grid-based surveillance strategy to ensure elimination and prevent reintroduction of malaria in high-risk border communities in China
  • 2022
  • Ingår i: BMC Public Health. - : Springer Nature. - 1471-2458. ; 22:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Grid management is a grassroots governance strategy widely implemented in China since 2004 to improve the government's efficiency to actively find and solve problems among populated regions. A grid-based strategy surveillancing high-risk groups, including mobile and migrant populations (MMPs), in the China-Myanmar border region has played an indispensable role in promoting and consolidating the malaria elimination efforts by tracking and timely identification of potential importation or re-establishment of malaria among MMPs. A sequential mixed methods was implementated to explore the operational mechanism and best practices of the grid-based strategy including through the focus group discussions (FGDs), comparison of before and after the implementation of a grid-based strategy in the field sites, and data collection from the local health system.This paper distills the implementation mechanism and highlights the role of the grid-based strategy in the elimination and prevention of re-establishment of malaria transmission.
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24.
  • Pan, Dong-Xiao, et al. (författare)
  • Rippled Electron-Scale Structure of a Dipolarization Front
  • 2018
  • Ingår i: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 45:22, s. 12116-12124
  • Tidskriftsartikel (refereegranskat)abstract
    • We use the Magnetospheric Multiscale mission to investigate electron-scale structures at a dipolarization front. The four spacecraft are separated by electron scales and observe large differences in plasma and field parameters within the dipolarization front, indicating strong deviation from typically assumed plane or slightly curved front surface. We attribute this to ripples generated by the lower hybrid drift instability (LHDI) with wave number of k(rho e)similar or equal to 0.4 and maximum wave potential of similar to 1 kV similar to k(B)T(e). Power law-like spectra of E-perpendicular to with slope of -3 indicates the turbulent cascade of LHDI. LHDI is observed together with bursty high-frequency parallel electric fields, suggesting coupling of LHDI to higher-frequency electrostatic waves. Plain Language Summary Dipolarization fronts (DFs) are narrow boundaries with sharp enhancement of magnetic field, located at the leading part of fast plasma jets observed in Earth's magnetotail. DFs are typically assumed to be smooth boundaries at scales comparable to the ion gyroradius and below. In this study, we use the four Magnetospheric Multiscale spacecraft separated by several electron gyroradii to investigate fine structure of a DF. Surprisingly, we observe significant differences in the fields and plasma measurements between the spacecraft despite their small separation. We attribute these signatures to electron-scale disturbances propagating along the DF surface, and thus the DF surface is not smooth as expected but rather rippled. The ripples develop as a result of a plasma instability driven by the strong inhomogeneities present at the DF. The fact that the ripples have such small scales means that they can effectively interact with plasma electrons.
  •  
25.
  • Xu, Hui, et al. (författare)
  • Impact of Pore Structure on Two-Electron Oxygen Reduction Reaction in Nitrogen-Doped Carbon Materials : Rotating Ring-Disk Electrode vs. Flow Cell
  • 2022
  • Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 15:5
  • Tidskriftsartikel (refereegranskat)abstract
    • The impact of pore structure on the two-electron oxygen reduction reaction (ORR) in nitrogen-doped carbon materials is currently under debate, and previous studies are mainly limited to the rotating ring-disk electrode (RRDE) rather than the practical flow cell (FC) system. In this study, assisted by a group of reliable pore models, the impact of two pore structure parameters, that is, Brunauer–Emmett–Teller surface area (SBET) and micropore surface fraction (fmicro), on ORR activity and selectivity are investigated in both RRDE and FC. The ORR mass activity correlates positively to the SBET in the RRDE and FC because a higher SBET can host more active sites. The H2O2 selectivity is independent of fmicro in the RRDE but correlates negatively to fmicro in the FC. The inconsistency results from different states of the electrode in the RRDE and the FC. These insights will guide the design of carbon materials for H2O2 synthesis.
  •  
26.
  • Xu, Weicheng, et al. (författare)
  • Nitrogen doping to accelerate the phase transition to ordered intermetallic Pt3Co catalyst for the oxygen reduction reaction in fuel cells
  • 2023
  • Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 11:8, s. 4078-4087
  • Tidskriftsartikel (refereegranskat)abstract
    • Ordered intermetallic Pt–M alloys are foreseen to be promising as next-generation low-Pt catalysts for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs) due to their high catalytic activity and stability. Nevertheless, the disorder-to-order intermetallic phase transition often needs to proceed at elevated annealing temperature for a long time, which leads to severe particle agglomeration. Herein, an efficient nitrogen (N)-doping strategy is developed to speed up such phase transition in an intermetallic Pt3Co alloy catalyst, which shortens the annealing duration by 3–5 fold at a temperature of 600–800 °C. Such a strategy can not only minimize the particle agglomeration but also effectively optimize the electronic structure of surface Pt atoms with the incorporated N. The prepared N-doped ordered intermetallic Pt3Co catalyst exhibits high ORR activity among the best of the state-of-the-art, with mass activities of 1.21 and 1.20 A mgPt−1 at 0.90 V in rotating disk electrode (RDE) and proton exchange membrane fuel cell (PEMFC) tests, respectively. Moreover, with the total Pt loading of 0.15 mgPt cm−2, the H2–air PEMFC delivers a power density of 1.27 W cm−2 at 150 kPaabs and 0.6 V, corresponding to a high Pt utilization of 0.118 gPt kW−1 that has surpassed the DOE 2025 target (0.125 gPt kW−1). This study paves a new way to develop high-performance low-Pt ORR catalysts for PEMFCs.
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27.
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