| 251. |
- Li, Xing-Yu, et al.
(författare)
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ULF Wave-Induced Ion Pitch Angle Evolution in the Dayside Outer Magnetosphere
- 2022
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Ingår i: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 49:8
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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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| 252. |
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| 253. |
- Liao, Xiaoqi, et al.
(författare)
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Superposition of conventional and spontaneous exchange bias in a Ni50Mn34In13Fe3 magnetic shape memory alloy
- 2019
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Ingår i: Journal of Alloys and Compounds. - : ELSEVIER SCIENCE SA. - 0925-8388 .- 1873-4669. ; 772, s. 988-993
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Tidskriftsartikel (refereegranskat)abstract
- The conventional exchange bias and spontaneous exchange bias are two interesting but fundamentally different effects in Mn rich Ni-Mn-Z magnetic shape memory alloys. Previous investigations show that these two phenomena appear separately. Here, we report that the conventional and spontaneous exchange bias phenomena coexist in a Ni50Mn34In13Fe3 alloy and the superposition of them increases the total exchange bias of the alloy. Our results suggest that the canonical spin glass and super spin glass may coexist and are embedded in the antiferromagnetic matrix of the martensite, through properly tuning the temperature-field history, which further results in the superposition of conventional and spontaneous exchange bias for this alloy. The interfacial interaction between the canonical spin glass and the antiferromagnetic matrix forms during field cooling process, which results in the conventional exchange bias. Moreover, the application of large magnetic field during the isothermal magnetization process changes the superspin glass into a superferromagnetic state, which interacts with the antiferromagnetic matrix at the interface, causing the spontaneous exchange bias. The superposition of exchange bias provides an effective way to achieve large exchange bias in materials. (C) 2018 Elsevier B.V. All rights reserved.
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| 254. |
- Lin, Chun-Yu, et al.
(författare)
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High levels of serum hyaluronan is an early predictor of dengue warning signs and perturbs vascular integrity
- 2019
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Ingår i: EBioMedicine. - : ELSEVIER. - 2352-3964. ; 48, s. 425-441
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Tidskriftsartikel (refereegranskat)abstract
- Background: A main pathological feature of severe dengue virus infection is endothelial hyper-permeability. The dengue virus nonstructural protein 1 (NS1) has been implicated in the vascular leakage that characterizes severe dengue virus infection, however, the molecular mechanisms involved are not known.Methods: A cohort of 250 dengue patients has been followed from the onset of symptoms to the recovery phase. Set urn hyaluronan levels and several other clinical parameters were recorded. The effect of NS1 treatment of cultured fibroblasts and endothelial cells on the expressions of hyaluronan synthetic and catabolic enzymes and the hyaluronan receptor CD44, were determined, as have the effects on the formation of hyaluronan-rich matrices and endothelial permeability.Findings: Elevated serum hyaluronan levels (70 ng/ml) during early infection was found to be an independent predictor for occurrence of warning signs, and thus severe dengue fever. High circulating levels of the viral protein NS1, indicative of disease severity, correlated with high concentrations of serum hyaluronan. NS1 exposure decreased the expression of CD44 in differentiating endothelial cells impairing the integrity of vessel-like structures, and promoted the synthesis of hyaluronan in dermal fibroblasts and endothelial cells in synergy with dengue-induced pro-inflammatory mediators. Deposited hyaluronan-rich matrices around cells cultured in vitro recruited CD44-expressing macrophage-like cells, suggesting a mechanism for enhancement of inflammation. In cultured endothelial cells, perturbed hyaluronan-CD44 interactions enhanced endothelial permeability through modulation of VE-cadherin and cytoskeleton re-organization, and exacerbated the NS1-induced disruption of endothelial integrity.Interpretation: Pharmacological targeting of hyaluronan biosynthesis and/or its CD44-mediated signaling may limit the life-threatening vascular leakiness during moderate-to-severe dengue virus infection.
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| 255. |
- Liu, Haoyu, et al.
(författare)
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Dietary Fiber in Bilberry Ameliorates Pre-Obesity Events in Rats by Regulating Lipid Depot, Cecal Short-Chain Fatty Acid Formation and Microbiota Composition
- 2019
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Ingår i: Nutrients. - : MDPI. - 2072-6643. ; 11:6
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Tidskriftsartikel (refereegranskat)abstract
- Obesity is linked to non-alcoholic fatty liver disease and risk factors associated to metabolic syndrome. Bilberry (Vaccinium myrtillus) that contains easily fermentable fiber may strengthen the intestinal barrier function, attenuate inflammation and modulate gut microbiota composition, thereby prevent obesity development. In the current study, liver lipid metabolism, fat depot, cecal and serum short-chain fatty acids (SCFAs) and gut microbiome were evaluated in rats fed bilberries in a high-fat (HFD + BB) or low-fat (LFD + BB) setting for 8 weeks and compared with diets containing equal amount of fiber resistant to fermentation (cellulose, HFD and LFD). HFD fed rats did not obtain an obese phenotype but underwent pre-obesity events including increased liver index, lipid accumulation and increased serum cholesterol levels. This was linked to shifts of cecal bacterial community and reduction of major SCFAs. Bilberry inclusion improved liver metabolism and serum lipid levels. Bilberry inclusion under either LFD or HFD, maintained microbiota homeostasis, stimulated interscapular-brown adipose tissue depot associated with increased mRNA expression of uncoupling protein-1; enhanced SCFAs in the cecum and circulation; and promoted butyric acid and butyrate-producing bacteria. These findings suggest that bilberry may serve as a preventative dietary measure to optimize microbiome and associated lipid metabolism during or prior to HFD.
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| 256. |
- Liu, Haoyu, et al.
(författare)
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High-Fat Diet Enriched with Bilberry Modifies Colonic Mucus Dynamics and Restores Marked Alterations of Gut Microbiome in Rats
- 2019
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Ingår i: Molecular Nutrition & Food Research. - : WILEY. - 1613-4125 .- 1613-4133. ; 63:20
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Tidskriftsartikel (refereegranskat)abstract
- Scope Emerging evidence suggests that high-fat diet (HFD) is associated with gut microbiome dysbiosis and related disorders. Bilberry is a prebiotic food component with known health benefits. Herein, the dynamics of the colonic mucus layer and microbiome during HFD and bilberry supplementation are addressed. Methods and results The effects on colonic mucus thickness in vivo and gut microbiota composition (Illumina sequencing, quantitative real-time PCR) are investigated in young rats fed a low-fat diet or HFD with or without bilberries for 8 weeks (n = 8). HFD induced significant local colonic effects, despite no observed weight gain or systemic inflammation, as HFD causes epithelial upregulation of inducible nitric oxide synthase, which is counteracted by bilberry. The firmly adherent mucus layer becomes thicker and the mRNA levels of Muc2 and Tff3 are increased by HFD with or without bilberry. In parallel, HFD reduced the colonic abundance of mucolytic bacterial species Akkermansia muciniphila and Bacteroides spp. Finally, bilberry prevents HFD-induced microbiota dysbiosis, including expansion of pathobionts, for example, Enterobacteriaceae. Conclusion HFD expand firmly adherent mucus thickness and reduce mucus-foraging bacteria populations in the colon prior to obesity. Enriching HFD with bilberry protects against intestinal inflammation and marked microbiota encroachment.
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| 257. |
- Liu, Kexin, et al.
(författare)
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100 Gbit/s THz Photonic Wireless Transmission in the 350-GHz Band With Extended Reach
- 2018
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Ingår i: IEEE Photonics Technology Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1041-1135 .- 1941-0174. ; 30:11, s. 1064-1067
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Tidskriftsartikel (refereegranskat)abstract
- In this letter, we experimentally demonstrate terahertz (THz) photonic wireless transmission of high-speed quadrature-phase-shift-keying (QPSK) and 16 quadrature amplitude modulation (16-QAM) signals in the 350-GHz band, with an effort to extend the wireless reach of ultrafast 100 Gbit/s. In the experiment, a narrowband unitraveling-carrier photodiode (UTC-PD) is used for heterodyne generation of THz communication signals, which is transparent to optical modulation formats. Experimental results show that 30 GBd/s QPSK (60 Gbit/s) and 25 GBd/s 16-QAM signals (100 Gbit/s) are successfully transmitted over a 350-GHz wireless link with an extended distance of 2 m. This enhancement is enabled by combining the techniques of employing cutting-edge narrowband UTC-PD as the photomixing THz emitter, spectrally efficient modulation format and advanced digital signal processing algorithms. The achievement makes 100 Gbit/s THz wireless communication systems promising for future smart wireless services.
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| 258. |
- Liu, Kexin, et al.
(författare)
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Enhanced Accessibility of 350 GHz 100 Gbit/s 16-QAM Photonic Wireless Link
- 2018
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Ingår i: Proceedings 11th UK-Europe-China Workshop on Millimetre-Waves and Terahertz Technologies (UCMMT) Vol 1. - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- We experimentally demonstrate an ultrafast terahertz (THz) photonic wireless communication link in the 350 GHz band with up to 100 Gbit/s data rate, with an emphasis on extending its wireless reach. By combining the techniques of using a cutting-edge narrow-band uni-traveling-carrier photodiode (UTC-PD) as the THz photo-mixing emitter, spectrally efficient modulation formats and advanced digital signal processing (DSP) algorithms, we successfully transmit 25 GBaud/s 16-quadrature amplitude modulation (16-QAM) signals (overall 100 Gbit/s data rate) over a 350 GHz wireless link with an extended distance of 2 m. This achievement pushes the accessibility of ultrafast 100 Gbit/s wireless communication beyond the state-of-the-art, and makes 100 Gbit/s ultrafast THz wireless communication systems promising for future smart high speed wireless access services.
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| 259. |
- Liu, Shaohui, et al.
(författare)
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Data-Driven Controlled Synthesis of Oriented Quasi-Spherical CsPbBr3 Perovskite Materials
- 2024
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Ingår i: Angewandte Chemie International Edition. - : WILEY-V C H VERLAG GMBH. - 1433-7851 .- 1521-3773. ; 63:14
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Tidskriftsartikel (refereegranskat)abstract
- Controlled synthesis of lead-halide perovskite crystals is challenging yet attractive because of the pivotal role played by the crystal structure and growth conditions in regulating their properties. This study introduces data-driven strategies for the controlled synthesis of oriented quasi-spherical CsPbBr3, alongside an investigation into the synthesis mechanism. High-throughput rapid characterization of absorption spectra and color under ultraviolet illumination was conducted using 23 possible ligands for the synthesis of CsPbBr3 crystals. The links between the absorption spectra slope (difference in the absorbance at 400 nm and 450 nm divided by a wavelength interval of 50 nm) and crystal size were determined through statistical analysis of more than 100 related publications. Big data analysis and machine learning were employed to investigate a total of 688 absorption spectra and 652 color values, revealing correlations between synthesis parameters and properties. Ex situ characterization confirmed successful synthesis of oriented quasi-spherical CsPbBr3 perovskites using polyvinylpyrrolidone and Acacia. Density functional theory calculations highlighted strong adsorption of Acacia on the (110) facet of CsPbBr3. Optical properties of the oriented quasi-spherical perovskites prepared with these data-driven strategies were significantly improved. This study demonstrates that data-driven controlled synthesis facilitates morphology-controlled perovskites with excellent optical properties.
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| 260. |
- Liu, Zhao-Di, et al.
(författare)
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Influence of the central metal on the crystal structures and electronic structures of biferrocene trinuclear complexes
- 2011
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Ingår i: Polyhedron. - : Elsevier. - 0277-5387 .- 1873-3719. ; 30:2, s. 279-283
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Tidskriftsartikel (refereegranskat)abstract
- Five metal-bridged biferrocene complexes of the Schiff-base ligand (HL = S-benzyl-N-(ferrocenyl-1-methyl-methylidene)dithiocarbazate) have been studied by single crystal X-ray diffraction and 57Fe Mössbauer spectroscopy. The crystal structures of the complexes show that the central metal ions are tetra-coordinated by two ligands in two modes: the central d8 transition metal ions (Ni2+, Pd2+, and Pt2+) are nearly square-planar coordinated and the d10 transition metal ions (Zn2+ and Cd2+) are tetrahedrally coordinated. Interestingly, the isomer shifts in 57Fe Mössbauer spectroscopy are also of two kinds: d8 transition metal ions (0.097–0.247 mm/s) and d10 transition metal ions (0.416–0.435 mm/s).
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