| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- Chen, Yihan, et al.
(författare)
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Characterization of the structure and analysis of the anti-oxidant effect of microalga Spirulina platensis polysaccharide on Caenorhabditis elegans mediated by modulating microRNAs and gut microbiota
- 2020
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Ingår i: International Journal of Biological Macromolecules. - : Elsevier BV. - 0141-8130 .- 1879-0003. ; 163, s. 2295-2305
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Tidskriftsartikel (refereegranskat)abstract
- The antioxidant activity of Spirulina platensis polysaccharide (SPP) was investigated in Caenorhabditis elegans. Nuclearmagnetic resonance, Fourier-transform infrared, multi-angle laser light scattering, and GC-MS were used to identify the structural characteristics of SPP. It was composed of the -> 2)-alpha-L-Rhap-(1 ->, -> 4)-beta-D-Manp-(1 ->, -> 6)-beta-D-Glcp-(1 ->, -> 4)-beta-Xylp-(1 ->, -> 3)-beta-L-Araf-(1 ->, and -> 2)-beta-L-Fucp-(1 ->, respectively. The modulation of gut microbiota in C. elegans was determined using 16S rRNA gene high-throughput sequencing. The malondialdehyde (MDA) content was significantly decreased, while the total superoxide dismutase (T-SOD) and reactive oxygen species (ROS) levels were improved after SPP supplementation. The cellular mitochondrial content and apoptosis were significantly down-regulated. The obvious increased levels of the DAF-16 and SKN-1 mRNAs were observed in the SPP-treated group, while the levels of miR-48 and miR-51 were significantly reduced. Moreover, SPP administration significantly increased the abundance of Flavobacterium, Achromobacter, Empedobacter, Anaerolinea, and Pseudoalteromonas of the intestinal flora. Based on these results, S. platensis polysaccharides may be used as a functional food to ameliorate diseases related to oxidative stress.
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| 3. |
- Abbasi, Rasha, et al.
(författare)
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IceCube search for neutrinos from GRB 221009A
- 2023
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Ingår i: Proceedings of 38th International Cosmic Ray Conference (ICRC 2023). - : Sissa Medialab Srl.
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Konferensbidrag (refereegranskat)abstract
- GRB 221009A is the brightest Gamma Ray Burst (GRB) ever observed. The observed extremelyhigh flux of high and very-high-energy photons provide a unique opportunity to probe the predictedneutrino counterpart to the electromagnetic emission. We have used a variety of methods to searchfor neutrinos in coincidence with the GRB over several time windows during the precursor, promptand afterglow phases of the GRB. MeV scale neutrinos are studied using photo-multiplier ratescalers which are normally used to search for galactic core-collapse supernovae neutrinos. GeVneutrinos are searched starting with DeepCore triggers. These events don’t have directionallocalization, but instead can indicate an excess in the rate of events. 10 GeV - 1 TeV and >TeVneutrinos are searched using traditional neutrino point source methods which take into accountthe direction and time of events with DeepCore and the entire IceCube detector respectively. The>TeV results include both a fast-response analysis conducted by IceCube in real-time with timewindows of T0 − 1 to T0 + 2 hours and T0 ± 1 day around the time of GRB 221009A, as well asan offline analysis with 3 new time windows up to a time window of T0 − 1 to T0 + 14 days, thelongest time period we consider. The combination of observations by IceCube covers 9 ordersof magnitude in neutrino energy, from MeV to PeV, placing upper limits across the range forpredicted neutrino emission.
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| 4. |
- Liu, Dan, et al.
(författare)
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Nutraceutical potentials of algal ulvan for healthy aging
- 2022
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Ingår i: International Journal of Biological Macromolecules. - : Elsevier. - 0141-8130 .- 1879-0003. ; 194, s. 422-434
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Forskningsöversikt (refereegranskat)abstract
- Several theories for aging are constantly put forth to explain the underlying mechanisms. Oxidative stress, DNA dysfunction, inflammation, and mitochondrial dysfunction, along with the release of cytochrome c are some of these theories. Diseases such as type 2 diabetes mellitus, intestinal dysfunction, cardiovascular diseases, hepatic injury, and even cancer develop with age and eventually cause death. Ulva polysaccharides, owing to their special structures and various functions, have emerged as desirable materials for keeping healthy. These polysaccharide structures are found to be closely related to the extraction methods, seaweed strains, and culture conditions. Ulvan is a promising bioactive substance, a potential functional food, which can regulate immune cells to augment inflammation, control the activity of aging-related genes, promote tumor senescence, enhance mitochondrial function, maintain liver balance, and protect the gut microbiome from inflammatory attacks. Given the desirable physiochemical and gelling properties of ulvan, it would serve to improve the quality and shelf-life of food.
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| 5. |
- Ouyang, Yuezhen, et al.
(författare)
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Cancer-fighting potentials of algal polysaccharides as nutraceuticals
- 2021
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Ingår i: Food Research International. - : Elsevier. - 0963-9969 .- 1873-7145. ; 147
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Tidskriftsartikel (refereegranskat)abstract
- Cancer has been listed as one of the world's five incurable diseases by the World Health Organization and causes tens of thousands of deaths every year. Unfortunately, anticancer agents either show limited efficacy or show serious side effects. The algae possess high nutritional value and their polysaccharides have a variety of biological activities, especially anti-cancer and immunomodulatory properties. Algal polysaccharides exert anticancer effects by inducing apoptosis, cell cycle arrest, anti-angiogenesis, and regulating intestinal flora and immune function. Algal polysaccharides can be combined with nanoparticles and other drugs to reduce the side effects caused by chemotherapy and increase the anticancer effects. This review shows the signal pathways related to the anti-cancer mechanisms of algal polysaccharides, including their influence on intestinal flora and immune regulation, the application of nanoparticles, and the effects on combination therapy and clinical trials of cancer treatments.
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| 6. |
- Chen, Zhuoer, 1989, et al.
(författare)
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Process variation in Laser Powder Bed Fusion of Ti-6Al-4V
- 2021
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Ingår i: Additive Manufacturing. - : Elsevier BV. - 2214-8604. ; 41
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Tidskriftsartikel (refereegranskat)abstract
- In this work, a concept of using surface roughness data as an evaluation tool of the process variation in a commercial Laser Powder Bed Fusion (L-PBF) machine is demonstrated. The interactive effects of powder recoating, spatter generation, gas flow and heat transfer are responsible for the intra-build quality inconsistency of the L-PBF process. Novel specimens and experiments were designed to investigate how surface roughness varies across the build volume and with the progression of a build. The variation in roughness has a clear and repeatable pattern due to the strong impact of the orientation of inclined surface to the laser origin. The effects of other factors such as exposure sequence of specimens, build height, and recoating process are less prominent and are difficult to isolate. A neural network regression model was built upon the large dataset in measured Ra values. The neural network model was applied to predict distribution of roughness within the build volume under hypothetical processing conditions. Connections between the predicted variation in roughness and underlying physical mechanisms are discussed. The present work has value for machine qualification and modifications which lead to the manufacturing of parts with better consistency in quality. The detailed variation observed in surface roughness can be used as a reference for designing experiments to optimise processing parameters in order to minimise the roughness of inclined surfaces.
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| 7. |
- Hong, Jie, et al.
(författare)
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Asymmetrically coupled co single-atom and co nanoparticle in double-shelled carbon-based nanoreactor for enhanced reversible oxygen catalysis
- 2023
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Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 455
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Tidskriftsartikel (refereegranskat)abstract
- Simultaneous construction of size-asymmetric metal single atoms and nanoparticle active sites in advanced and robust carrier materials is particularly important yet challenging for efficient reversible oxygen catalysis. Herein, a facile “chemical etching/in-Situ capture” synthesis strategy was developed to fabricate a unique double-shelled carbon-based nanobox integrated with size-asymmetric Co single-atom (CoSA) and metallic Co nanoparticle (CoNP) moiety. As expected, this well-managed catalyst product yielded remarkable bifunctional electrocatalytic performances in alkaline electrolytes, with a decent half-wave potential of 0.886 V for oxygen reduction reaction (ORR) and a small overpotential of 341 mV at 10 mA/cm2 for oxygen evolution reaction (OER). Besides, this nanobox catalyst served as a cost-effective and efficient oxygen electrode in the assembled rechargeable ZABs, exceeding the mixed electrocatalyst of expensive Pt/C-RuO2, in terms of the elevated peak power density of 239 mW/cm2, the promoted specific capacity of 770 mAh/gZn, as well as the appreciable charge–discharge cycle stability. Theoretical calculations revealed that the strong interaction between the delicate CoSA site and CoNP phase, could effectively optimize the adsorption and desorption energy barriers of reaction intermediates on the designed catalyst surface, thus achieving synergistic enhancement of electrocatalytic activity towards ORR and OER. This finding affords a feasible and effective strategy to achieve highly active and durable bifunctional catalysts for both fundamental research and practical rechargeable ZABs applications.
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| 8. |
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| 9. |
- Li, Ziyao, et al.
(författare)
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Atomic-level orbital coupling in a tri-metal alloy site enables highly efficient reversible oxygen electrocatalysis
- 2023
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 11:5, s. 2155-2167
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Tidskriftsartikel (refereegranskat)abstract
- Complex multi-metallic alloys with ultra-small sizes have received extensive attention in the fields of Zn-air battery and water splitting, because of their unique advantages including adjustable composition, tailorable active sites, and optimizable electronic structure. In this effort, an atomic-level orbital coupling strategy is presented to effectively regulate the electronic structures of ultra-small tri-metal Fe-Co-Ni nanoalloy particles confined in an N-doped carbon hollow nanobox. As expected, the optimal nanoalloy hybrid material exhibited notable bi-functional catalytic performances toward the oxygen reduction reaction (half-wave potential of 0.902 V) and oxygen evolution reaction (1.589 V at 10 mA cm−2) with a small ΔE of 0.687 V, exceeding the precious-metal-based and many previously reported catalysts. Furthermore, the as-assembled Zn-air device also displayed a superior specific capacity of 894 mA h g−1, a maximal power density of 247 mW cm−2, and impressive durability (over 100 hours). Ultraviolet photoelectron spectroscopy and density functional theory calculations revealed that the electronic structures could be finely tuned and optimized through ternary metal alloying, resulting in a suitable d-band center and advantageous interfacial charge-transfer, which in turn could effectively reduce the involved energy barriers in the electrocatalytic process and significantly boost its intrinsic activity of reversible oxygen catalysis. Thus, this work affords an effective method for the rational creation of bi-functional non-noble-metal-based electrocatalysts for sustainable energy technology.
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| 10. |
- Nie, Zhicheng, et al.
(författare)
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Tailoring the d-band center by intermetallic charge-transfer manipulation in bimetal alloy nanoparticle confined in N-doped carbon nanobox for efficient rechargeable Zn-air battery
- 2023
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Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 463
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Tidskriftsartikel (refereegranskat)abstract
- In this effort, the electronic-structure modulation strategy through nano-alloying was rationally designed to fabricate Fe-Ni alloy particles embedded in an N-doped carbon nanobox. The as-developed catalyst outperformed the commercialized noble-metal benchmarks with a decent half-wave potential of 0.891 V for ORR and a small overpotential of 325 mV at 10 mA/cm2 for OER both in 0.1 M KOH solution. Beyond that, a highly-efficient regenerative Zn-air battery was also successfully constructed, evidenced by a small potential gap of 0.664 V (between Ej=10 and E1/2), a high specific capacity of 763 mAh/g, a large peak power density of 270 mW/cm2, and robust stability. Ultraviolet photoelectron spectroscopy and theoretical simulation confirmed that the alloying of Ni into Fe could well manipulate the electronic structure, leading to favorable intermetallic charge-transfer and then downshifting the d-band center of Fe adsorption sites, all of which help to significantly lower the reaction barriers of the involved intermediates during the electrocatalytic ORR/OER processes.
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