| 1. |
- Shuoker, Bashar, et al.
(författare)
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Sialidases and fucosidases of Akkermansia muciniphila are crucial for growth on mucin and nutrient sharing with mucus-associated gut bacteria
- 2023
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Ingår i: Nature Communications. - 2041-1723. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- The mucolytic human gut microbiota specialist Akkermansia muciniphila is proposed to boost mucin-secretion by the host, thereby being a key player in mucus turnover. Mucin glycan utilization requires the removal of protective caps, notably fucose and sialic acid, but the enzymatic details of this process remain largely unknown. Here, we describe the specificities of ten A. muciniphila glycoside hydrolases, which collectively remove all known sialyl and fucosyl mucin caps including those on double-sulfated epitopes. Structural analyses revealed an unprecedented fucosidase modular arrangement and explained the sialyl T-antigen specificity of a sialidase of a previously unknown family. Cell-attached sialidases and fucosidases displayed mucin-binding and their inhibition abolished growth of A. muciniphila on mucin. Remarkably, neither the sialic acid nor fucose contributed to A. muciniphila growth, but instead promoted butyrate production by co-cultured Clostridia. This study brings unprecedented mechanistic insight into the initiation of mucin O-glycan degradation by A. muciniphila and nutrient sharing between mucus-associated bacteria.
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| 2. |
- Yang, Heyi, et al.
(författare)
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Composition-Conditioning Agent for Doped Spiro-OMeTAD to Realize Highly Efficient and Stable Perovskite Solar Cells
- 2022
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Ingår i: Advanced Energy Materials. - : WILEY-V C H VERLAG GMBH. - 1614-6832 .- 1614-6840. ; 12:44
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Tidskriftsartikel (refereegranskat)abstract
- The doped Spiro-OMeTAD hole transport layer (HTL) formed using the lithium bis(trifluoromethane) sulfonimide salt and 4-tert-butylpyridine with phenethylammonium iodide surface treatment on a perovskite film has continuously dominated the record power conversion efficiencies (PCEs) of perovskite solar cells (pero-SCs). However, unstable HTL compositions and iodide salts can cause severe device degradation. In this study, an HTL composition-conditioning agent (CCA), Spiro-BD-2OEG, is designed, which contains a Spiro-OMeTAD-like backbone, functional pyridine units, and oligo (ethylene glycol) chains. This finely designed CCA presents good miscibility with Spiro-OMeTAD and its dopants and acts as a conditioning agent through weak bond interactions. As a result, the CCA-regulated HTL shows a pinhole-free and smooth morphology with enhanced Spiro-OMeTAD ordering and improves dopant stability. In addition, the gradient-distributed CCA in the HTL can narrow the energy level offset with the valence band of the perovskite. The resultant pero-SCs exhibit an excellent PCE of 24.19% without any interface treatment and weak size dependence. A remarkable PCE of 22.63% is obtained even for a 1.004-cm(2) device. Importantly, the strategy shows good universality and significantly promotes the long-term stability of the pero-SCs based on the classical doped Spiro-OMeTAD.
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| 3. |
- Zhang, Jin, et al.
(författare)
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Comparison of Implicit and Explicit Solvent Models for the Calculation of Solvation Free Energy in Organic Solvents
- 2017
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Ingår i: Journal of Chemical Theory and Computation. - : AMER CHEMICAL SOC. - 1549-9618 .- 1549-9626. ; 13:3, s. 1034-1043
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Tidskriftsartikel (refereegranskat)abstract
- Quantitative prediction of physical properties of liquids is important for many applications. Computational methods based on either explicit or implicit solvent models can be used to approximate thermodynamics properties of liquids. Here, we evaluate the predictive power of implicit solvent models for solvation free energy of organic molecules in organic solvents. We compared the results calculated with four generalized Born (GB) models (GB(still), GB(HCT), GB(OBC)I, and GB(OBC)IT), the Poisson Boltzmann (PB) model, and the density-based solvent model SMD with previous solvation free energy calculations (Zhang et al. J. Chem. Inf. Model. 2015, SS, 1192-1201) and experimental data. The comparison indicates that both PB and GB give poor agreement with explicit solvent calculations and even worse agreement with experiments (root mean -square deviation approximate to 15 kJ/mol). The main problem seems to be the prediction of the apolar contribution, which should include the solvent entropy. The quantum mechanical-based SMD model gives significantly better agreement with experimental data than do PB or GB, but it is not as good as explicit solvent calculation results. The dielectric constant a of the solvent is found to be a powerful predictor for the polar contribution to the free energy in implicit models; however, the Onsager relation may not hold for realistic solvent, as suggested by explicit solvent and SMD calculations. From the comparison, we also find that with an optimization of the apolar contribution, the PB model gives slightly better agreement with experiments than the SMD model, whereas the correlation between the optimized GB models and experiments remains poor. Further optimization of the apolar contribution is needed for GB models to be able to treat solvents other than water.
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