| 1. |
- Chen, Ruoxin, et al.
(författare)
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Structure-immunomodulatory activity relationships of dietary polysaccharides
- 2022
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Ingår i: CURRENT RESEARCH IN FOOD SCIENCE. - : Elsevier. - 2665-9271. ; 5, s. 1330-1341
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Tidskriftsartikel (refereegranskat)abstract
- Polysaccharides are usually composed of more than ten monosaccharide units, which are connected by linear or branched glycosidic bonds. The immunomodulatory effect of natural polysaccharides is one of the most important bioactive function. In this review, molecular weight, monosaccharide (including galactose, mannose, rhamnogalacturonan-I arabinogalactan and uronic acid), functional groups (namely sulfate, selenium, and acetyl groups), types of glycoside bond connection (including 13-1,3-D-glucosyl, alpha-1,4-D-glucosyl, 13-1,4-D-glucosyl, alpha-1,6-D-glucosyl, 13-1,4-D-mannosyl, and 13-1,4-D-Xylopyranosyl), conformation and the branching degrees are systematically identified as their contribution to the immunostimulatory activity of polysaccharides. At present, studies on the structure-activity relationships of polysaccharides are limited due to their low purity and high heterogeneity. However, it is an important step in providing useful guidance for dietary supplements with polysaccharides. The chemical structures and the process of immune responses induced are necessary to be discussed. Polysaccharides may bind with the cell surface receptors to modulate immune responses. This review mainly discusses the structure-activity relationship of dietary polysaccharides.
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| 2. |
- Chen, Yuxi, et al.
(författare)
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Global Three-Dimensional Simulation of Earth's Dayside Reconnection Using a Two-Way Coupled Magnetohydrodynamics With Embedded Particle-in-Cell Model : Initial Results
- 2017
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Ingår i: Journal of Geophysical Research - Space Physics. - : AMER GEOPHYSICAL UNION. - 2169-9380 .- 2169-9402. ; 122:10, s. 10318-10335
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Tidskriftsartikel (refereegranskat)abstract
- We perform a three-dimensional (3-D) global simulation of Earth's magnetosphere with kinetic reconnection physics to study the flux transfer events (FTEs) and dayside magnetic reconnection with the recently developed magnetohydrodynamics with embedded particle-in-cell model. During the 1 h long simulation, the FTEs are generated quasi-periodically near the subsolar point and move toward the poles. We find that the magnetic field signature of FTEs at their early formation stage is similar to a "crater FTE," which is characterized by a magnetic field strength dip at the FTE center. After the FTE core field grows to a significant value, it becomes an FTE with typical flux rope structure. When an FTE moves across the cusp, reconnection between the FTE field lines and the cusp field lines can dissipate the FTE. The kinetic features are also captured by our model. A crescent electron phase space distribution is found near the reconnection site. A similar distribution is found for ions at the location where the Larmor electric field appears. The lower hybrid drift instability (LHDI) along the current sheet direction also arises at the interface of magnetosheath and magnetosphere plasma. The LHDI electric field is about 8 mV/m, and its dominant wavelength relative to the electron gyroradius agrees reasonably with Magnetospheric Multiscale (MMS) observations.
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| 3. |
- Chen, Yuxi, et al.
(författare)
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Magnetohydrodynamic With Embedded Particle-In-Cell Simulation of the Geospace Environment Modeling Dayside Kinetic Processes Challenge Event
- 2020
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Ingår i: Earth and Space Science. - : American Geophysical Union (AGU). - 2333-5084. ; 7:11
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Tidskriftsartikel (refereegranskat)abstract
- We use the magnetohydrodynamic (MHD) with embedded particle-in-cell model (MHD-EPIC) to study the Geospace Environment Modeling (GEM) dayside kinetic processes challenge event at 01:50-03:00 UT on 18 November 2015, when the magnetosphere was driven by a steady southward interplanetary magnetic field (IMF). In the MHD-EPIC simulation, the dayside magnetopause is covered by a PIC code so that the dayside reconnection is properly handled. We compare the magnetic fields and the plasma profiles of the magnetopause crossing with the MMS3 spacecraft observations. Most variables match the observations well in the magnetosphere, in the magnetosheath, and also during the current sheet crossing. The MHD-EPIC simulation produces flux ropes, and we demonstrate that some magnetic field and plasma features observed by the MMS3 spacecraft can be reproduced by a flux rope crossing event. We use an algorithm to automatically identify the reconnection sites from the simulation results. It turns out that there are usually multiple X-lines at the magnetopause. By tracing the locations of the X-lines, we find that the typical moving speed of the X-line endpoints is about 70 km/s, which is higher than but still comparable with the ground-based observations.
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| 4. |
- Chen, Zhengxin, et al.
(författare)
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Recent advances of natural pigments from algae
- 2023
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Ingår i: FOOD PRODUCTION PROCESSING AND NUTRITION. - : BioMed Central (BMC). - 2661-8974. ; 5
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Forskningsöversikt (refereegranskat)abstract
- Pigment is an important food additive that plays a major role in the sensory impact of food. And natural sources, healthy and non-toxic edible pigments are receiving a lot of attention. Algae is an important source of natural pigments, and contain chlorophyll, phycoerythrin, carotene, and other natural pigments. Besides staining, the pigment also has powerful physiological activities such as antioxidants, anti-inflammatory, anti-obesity, and lipid-lowering. In this paper, three pigments in seaweed were reviewed, and their main structural properties and functions are presented, filling the gap in the review of pigments with seaweed as the main object of introduction. This review provides research basis for the development of new health foods, a new direction for the use of seaweed chlorophyll in the food and pharmaceutical industries.
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| 5. |
- Hedi, Wen, et al.
(författare)
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γ-Cyclodextrin-BSA for nano-encapsulation of hydrophobic substance
- 2021
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Ingår i: Food Bioscience. - : Elsevier. - 2212-4292 .- 2212-4306. ; 41
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Tidskriftsartikel (refereegranskat)abstract
- Self-aggregation and the hemolytic effect limit the application of gamma-cyclodextrin (gamma-CD) in bioactive molecular delivery systems. In this study, gamma-CD was modified by grafting onto bovine serum albumin protein (BSA), with epichlorohydrin (ECH) acting as the cross-linking agent. The effects of BSA concentration, reaction temperature, pH and time on the grafting rate were studied, and the gamma-CD-BSA complex with a grafting rate of 99.5 +/- 0.1% +/- 0.06)% was achieved. The complex was confirmed using H-1 NMR and FT-IR spectra. Compared with gamma-CD, the hemolytic effect and self-aggregation of gamma-CD-BSA were significantly reduced, and the encapsulation efficiency of curcumin was increased by 10.8%. The results of scanning electron microscopy showed that both gamma-CD and gamma-CDBSA nanoparticles were formed and the structure of the gamma-CD-BSA complex was more uniform. The pH stability and salt stability of gamma-CD-BSA were higher than gamma-CD. The release rate of gamma-CD-BSA was 15.2 +/- 0.2% after 2 h at pH 1.2, and 57 +/- 1% after 4 h at pH 7.2. The gamma-CD-BSA nanoparticles could protect curcumin in acidic environments and release it in neutral environments. The results suggested a promising wall material for delivery of hydrophobic substances.
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| 6. |
- Li, Yu-Feng, et al.
(författare)
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Organic Selenium Supplementation Increases Mercury Excretion and Decreases Oxidative Damage in Long-Term Mercury-Exposed Residents from Wanshan, China
- 2012
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 46:20, s. 11313-11318
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Tidskriftsartikel (refereegranskat)abstract
- Due to a long history of extensive mercury mining and smelting activities, local residents in Wanshan, China, are suffering from elevated mercury exposure. The objective of the present study was to study the effects of oral supplementation with selenium-enriched yeast in these long-term mercury-exposed populations. One hundred and three volunteers from Wanshan area were recruited and 53 of them were supplemented with 100 mu g of organic selenium daily as selenium-enriched yeast while 50 of them were supplemented with the nonselenium-enriched yeast for 3 months. The effects of selenium supplementation on urinary mercury, selenium, and oxidative stress-related biomarkers including malondialdehyde and 8-ydroxy-2-deoxyguanosine were assessed. This 3-month selenium supplementation trial indicated that organic selenium supplementation could increase mercury excretion and decrease urinary malondialdehyde and 8-hydroxy-2-deoxyguanosine levels in local residents.
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| 7. |
- Luo, Biying, et al.
(författare)
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Bioactive phytochemicals and their potential roles in modulating gut microbiota
- 2023
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Ingår i: JOURNAL OF AGRICULTURE AND FOOD RESEARCH. - : Elsevier. - 2666-1543. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Dietary phytochemicals, including polyphenols, sulfur-containing compounds, terpenoids, polysaccharides, saponins, pigments, and phytohaemagglutinins, have antioxidant, anti-inflammatory, antiviral, and cancerpreventive or therapeutic properties. Upon entering the body, these compounds pass through the stomach, liver, small intestine, and colon in that order. Bacteria play an important role in the absorption and processing of dietary phytochemicals in the small intestine and in the large intestine. However, the specific processes by which dietary phytochemicals are absorbed and metabolized in the host colon have not been elucidated. This paper describes the metabolism of phytochemicals (including polyphenols, terpenoids, and plant organosulfides) in the colon and describes the roles played by these dietary phytochemicals in the colon, with emphasis on their effects on the gut microbiota. Upon entry into the host, phytochemicals are absorbed and metabolized mainly in the colon, and the differences in their absorption and metabolism are largely due to differences in the colonic microbiota. Moreover, phytochemicals can be absorbed in the intestine by acting on them through enzymes produced by intestinal cells and stem cells, or by interacting with the intestinal flora, thus ameliorating the associated diseases.
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| 8. |
- Ma, Yingjuan, et al.
(författare)
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Reconnection in the Martian Magnetotail : Hall-MHD With Embedded Particle-in-Cell Simulations
- 2018
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Ingår i: Journal of Geophysical Research - Space Physics. - : AMER GEOPHYSICAL UNION. - 2169-9380 .- 2169-9402. ; 123:5, s. 3742-3763
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Tidskriftsartikel (refereegranskat)abstract
- Mars Atmosphere and Volatile EvolutioN (MAVEN) mission observations show clear evidence of the occurrence of the magnetic reconnection process in the Martian plasma tail. In this study, we use sophisticated numerical models to help us understand the effects of magnetic reconnection in the plasma tail. The numerical models used in this study are (a) a multispecies global Hall-magnetohydrodynamic (HMHD) model and (b) a global HMHD model two-way coupled to an embedded fully kinetic particle-in-cell code. Comparison with MAVEN observations clearly shows that the general interaction pattern is well reproduced by the global HMHD model. The coupled model takes advantage of both the efficiency of the MHD model and the ability to incorporate kinetic processes of the particle-in-cell model, making it feasible to conduct kinetic simulations for Mars under realistic solar wind conditions for the first time. Results from the coupled model show that the Martian magnetotail is highly dynamic due to magnetic reconnection, and the resulting Mars-ward plasma flow velocities are significantly higher for the lighter ion fluid, which are quantitatively consistent with MAVEN observations. The HMHD with Embedded Particle-in-Cell model predicts that the ion loss rates are more variable but with similar mean values as compared with HMHD model results.
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| 9. |
- Markidis, Stefano, et al.
(författare)
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Kinetic Modeling in the Magnetosphere
- 2021
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Ingår i: Magnetospheres in the Solar System. - : Wiley. ; , s. 607-615
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents the state of the art of kinetic modeling techniques for simulating plasma kinetic dynamics in magnetospheres. We describe the key numerical techniques for enabling large-scale kinetic simulations of magnetospheres: parameter scaling, implicit Particle-in-Cell schemes and fluid-kinetic coupling. We show an application of these techniques to study particle acceleration and heating in asymmetric magnetic reconnection in the Ganymede magnetosphere.
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| 10. |
- Shuaishuai, Wang, et al.
(författare)
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Facile Chemoenzymatic Synthesis of O-Mannosyl Glycans
- 2018
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Ingår i: Angewandte Chemie International Edition. - : Wiley-VCH Verlagsgesellschaft. - 1433-7851 .- 1521-3773. ; 57:30, s. 9268-9273
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Tidskriftsartikel (refereegranskat)abstract
- Abstract O?Mannosylation is a vital protein modification involved in brain and muscle development whereas the biological relevance of O-mannosyl glycans has remained largely unknown owing to the lack of structurally defined glycoforms. An efficient scaffold synthesis/enzymatic extension (SSEE) strategy was developed to prepare such structures by combining gram-scale convergent chemical syntheses of three scaffolds and strictly controlled sequential enzymatic extension catalyzed by glycosyltransferases. In total, 45 O-mannosyl glycans were obtained, covering the majority of identified mammalian structures. Subsequent glycan microarray analysis revealed fine specificities of glycan-binding proteins and specific antisera.
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