| 1. |
- Fan, Y., et al.
(author)
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The gut microbiota contributes to the pathogenesis of anorexia nervosa in humans and mice
- 2023
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In: Nature Microbiology. - : Nature Publishing Group. - 2058-5276. ; 8, s. 787-802
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Journal article (peer-reviewed)abstract
- Anorexia nervosa (AN) is an eating disorder with a high mortality. About 95% of cases are women and it has a population prevalence of about 1%, but evidence-based treatment is lacking. The pathogenesis of AN probably involves genetics and various environmental factors, and an altered gut microbiota has been observed in individuals with AN using amplicon sequencing and relatively small cohorts. Here we investigated whether a disrupted gut microbiota contributes to AN pathogenesis. Shotgun metagenomics and metabolomics were performed on faecal and serum samples, respectively, from a cohort of 77 females with AN and 70 healthy females. Multiple bacterial taxa (for example, Clostridium species) were altered in AN and correlated with estimates of eating behaviour and mental health. The gut virome was also altered in AN including a reduction in viral-bacterial interactions. Bacterial functional modules associated with the degradation of neurotransmitters were enriched in AN and various structural variants in bacteria were linked to metabolic features of AN. Serum metabolomics revealed an increase in metabolites associated with reduced food intake (for example, indole-3-propionic acid). Causal inference analyses implied that serum bacterial metabolites are potentially mediating the impact of an altered gut microbiota on AN behaviour. Further, we performed faecal microbiota transplantation from AN cases to germ-free mice under energy-restricted feeding to mirror AN eating behaviour. We found that the reduced weight gain and induced hypothalamic and adipose tissue gene expression were related to aberrant energy metabolism and eating behaviour. Our 'omics' and mechanistic studies imply that a disruptive gut microbiome may contribute to AN pathogenesis. Faecal metagenomics and serum metabolomics reveal compositional and functional alterations in the gut microbiota of women with anorexia nervosa, and faecal transplants could transfer an anorexia-associated phenotype to germ-free mice.
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| 2. |
- Bi, Zhaoxia, et al.
(author)
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Self-assembled InN quantum dots on side facets of GaN nanowires
- 2018
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In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 123:16
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Journal article (peer-reviewed)abstract
- Self-assembled, atomic diffusion controlled growth of InN quantum dots was realized on the side facets of dislocation-free and c-oriented GaN nanowires having a hexagonal cross-section. The nanowires were synthesized by selective area metal organic vapor phase epitaxy. A 3 Å thick InN wetting layer was observed after growth, on top of which the InN quantum dots formed, indicating self-assembly in the Stranski-Krastanow growth mode. We found that the InN quantum dots can be tuned to nucleate either preferentially at the edges between GaN nanowire side facets, or directly on the side facets by tuning the adatom migration by controlling the precursor supersaturation and growth temperature. Structural characterization by transmission electron microscopy and reciprocal space mapping show that the InN quantum dots are close to be fully relaxed (residual strain below 1%) and that the c-planes of the InN quantum dots are tilted with respect to the GaN core. The strain relaxes mainly by the formation of misfit dislocations, observed with a periodicity of 3.2 nm at the InN and GaN hetero-interface. The misfit dislocations introduce I1 type stacking faults (...ABABCBC...) in the InN quantum dots. Photoluminescence investigations of the InN quantum dots show that the emissions shift to higher energy with reduced quantum dot size, which we attribute to increased quantum confinement.
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| 3. |
- Dzhigaev, D., et al.
(author)
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Bragg coherent x-ray diffractive imaging of a single indium phosphide nanowire
- 2016
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In: Journal of Optics. - : IOP Publishing. - 2040-8978 .- 2040-8986. ; 18:6
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Journal article (peer-reviewed)abstract
- Three-dimensional (3D) Bragg coherent x-ray diffractive imaging (CXDI) with a nanofocused beam was applied to quantitatively map the internal strain field of a single indium phosphide nanowire. The quantitative values of the strain were obtained by pre-characterization of the beam profile with transmission ptychography on a test sample. Our measurements revealed the 3D strain distribution in a region of 150 nm below the catalyst Au particle. We observed a slight gradient of the strain in the range of 0.6% along the [111] growth direction of the nanowire. We also determined the spatial resolution in our measurements to be about 10 nm in the direction perpendicular to the facets of the nanowire. The CXDI measurements were compared with the finite element method simulations and show a good agreement with our experimental results. The proposed approach can become an effective tool for in operando studies of the nanowires.
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| 4. |
- Engblom, C., et al.
(author)
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Overview of some feedback-&control systems at synchrotron SolEIL
- 2016
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In: Proceedings of the 11th International Workshop on Personal Computers and Particle Accelerator Controls, PCaPAC 2016. - 9783954501892 ; , s. 132-136
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Conference paper (peer-reviewed)abstract
- This paper gives an overview of some feedback & control systems at Synchrotron SOLEIL that are in use or in development today. Beam stability is crucial and adressed in all SOLEIL aspects; Fast Orbit Feedback is a multi-input multi-output control system made to stabilize beam position perturbations in the low- & high frequency band. In addition, active RF cavities are used to maintain stable beam energy & spread as well as keeping electron density even throughout the storage ring. Beam stability also comes from feedforward non-linear control in particle trajectory compensation on both sides of electromagnetic undulators. On some beamlines, multi-actuator piezos or pneumatics are used to regulate photon flux to keep within detector operating range; a method to maximize the photon flux while still keeping below detector damage thresholds. Currently in development & at the sample stage level, the Nanoprobe Project collaboration (MAXIV & SOLEIL) focuses on sample stabilization during step- & fly- scans which is realized through multi-axis nano-positioning with high- & low- frequency closed-loop control implementing interferometer feedback &/or compensation tables.
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