| 1. |
- Chergui, Majed, et al.
(författare)
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Progress and prospects in nonlinear extreme-ultraviolet and X-ray optics and spectroscopy
- 2023
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Ingår i: Nature reviews physics. - 2522-5820. ; :5, s. 578-596
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Forskningsöversikt (refereegranskat)abstract
- Free-electron lasers and high-harmonic-generation table-top systems are new sources of extreme-ultraviolet to hard X-ray photons, providing ultrashort pulses that are intense, coherent and tunable. They are enabling a broad range of nonlinear optical and spectroscopic methods at short wavelengths, similar to those developed in the terahertz to ultraviolet regimes over the past 60 years. The extreme-ultraviolet to X-ray wavelengths access core transitions that can provide element and orbital selectivity, structural resolution down to the sub-nanometre scale and, for some methods, high momentum transfers across typical Brillouin zones; the possibilities for polarization control and sub-femtosecond time resolution are opening up new frontiers in research. In this Roadmap, we review the emergence of this field over the past 10 years or so, covering methods such as sum or difference frequency generation and second-harmonic generation, two-photon absorption, stimulated emission or Raman spectroscopy and transient grating spectroscopy. We then discuss the unique opportunities provided by these techniques for probing elementary dynamics in a wide variety of systems. X-ray free-electron lasers and high-harmonic-generation sources of extreme-ultraviolet (EUV) to hard X-ray photons deliver intense ultrashort pulses and enable the extension of nonlinear methods to much shorter wavelengths.EUV to X-ray wavelengths access core transitions that can provide element and orbital selectivity. These wavelengths also achieve sub-nanometre structural resolution and high momentum transfer, with femtosecond and attosecond time resolution.Nonlinear EUV/X-ray methods that have emerged include sum or difference frequency generation, parametric down-conversion, second-harmonic generation, two-photon absorption, stimulated emission or Raman spectroscopy and transient grating spectroscopy.Nonlinear EUV/X-ray science is developing hand-in-hand with instrumentation, to improve pulse features and enhance accessibility with the use of table-top systems or compact accelerators.These techniques offer unique opportunities for probing dynamical events in a wide variety of systems, including surface and interface processes, chirality, nanoscale transport and multidimensional core-level spectroscopy. New sources of extreme-ultraviolet to hard X-ray photons have enabled a wide range of short-wavelength nonlinear optical and spectroscopic methods over the past decade, and, for the future, offer unique opportunities to probe elementary dynamics in various systems.
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| 2. |
- Michaels, Thomas C.T., et al.
(författare)
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Amyloid formation as a protein phase transition
- 2023
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Ingår i: Nature Reviews Physics. - 2522-5820. ; 5:7, s. 379-397
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Forskningsöversikt (refereegranskat)abstract
- The formation of amyloid fibrils is a general class of protein self-assembly behaviour, which is associated with both functional biology and the development of a number of disorders, such as Alzheimer and Parkinson diseases. In this Review, we discuss how general physical concepts from the study of phase transitions can be used to illuminate the fundamental mechanisms of amyloid self-assembly. We summarize progress in the efforts to describe the essential biophysical features of amyloid self-assembly as a nucleation-and-growth process and discuss how master equation approaches can reveal the key molecular pathways underlying this process, including the role of secondary nucleation. Additionally, we outline how non-classical aspects of aggregate formation involving oligomers or biomolecular condensates have emerged, inspiring developments in understanding, modelling and modulating complex protein assembly pathways. Finally, we consider how these concepts can be applied to kinetics-based drug discovery and therapeutic design to develop treatments for protein aggregation diseases.
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| 3. |
- Vinuesa, Ricardo, et al.
(författare)
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The transformative potential of machine learning for experiments in fluid mechanics
- 2023
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Ingår i: Nature Reviews Physics. - : Springer Nature. - 2522-5820. ; 5:9, s. 536-545
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Tidskriftsartikel (refereegranskat)abstract
- The field of machine learning (ML) has rapidly advanced the state of the art in many fields of science and engineering, including experimental fluid dynamics, which is one of the original big-data disciplines. This Perspective article highlights several aspects of experimental fluid mechanics that stand to benefit from progress in ML, including augmenting the fidelity and quality of measurement techniques, improving experimental design and surrogate digital-twin models and enabling real-time estimation and control. In each case, we discuss recent success stories and ongoing challenges, along with caveats and limitations, and outline the potential for new avenues of ML-augmented and ML-enabled experimental fluid mechanics.
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