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Sökning: WFRF:(Appio Roberto)

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1.
  • Allaria, E., et al. (författare)
  • Highly coherent and stable pulses from the FERMI seeded free-electron laser in the extreme ultraviolet
  • 2012
  • Ingår i: Nature Photonics. - 1749-4885. ; 6:10, s. 699-704
  • Tidskriftsartikel (refereegranskat)abstract
    • Free-electron lasers (FELs) are promising devices for generating light with laser-like properties in the extreme ultraviolet and X-ray spectral regions. Recently, FELs based on the self-amplified spontaneous emission (SASE) mechanism have allowed major breakthroughs in diffraction and spectroscopy applications, despite the relatively large shot-to-shot intensity and photon-energy fluctuations and the limited longitudinal coherence inherent in the SASE mechanism. Here, we report results on the initial performance of the FERMI seeded FEL, based on the high-gain harmonic generation configuration, in which an external laser is used to initiate the emission process. Emission from the FERMI FEL-1 source occurs in the form of pulses carrying energy of several tens of microjoules per pulse and tunable throughout the 65 to 20 nm wavelength range, with unprecedented shot-to-shot wavelength stability, low-intensity fluctuations, close to transform-limited bandwidth, transverse and longitudinal coherence and full control of polarization.
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2.
  • Björling, Alexander, 1983, et al. (författare)
  • Ubiquitous Structural Signaling in Bacterial Phytochromes
  • 2015
  • Ingår i: Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 6:17, s. 3379-3383
  • Tidskriftsartikel (refereegranskat)abstract
    • The phytochrome family of light-switchable proteins has long been studied by biochemical, spectroscopic and crystallographic means, while a direct probe for global conformational signal propagation has been lacking. Using solution X-ray scattering, we find that the photosensory cores of several bacterial phytochromes undergo similar large-scale structural changes upon red-light excitation. The data establish that phytochromes with ordinary and inverted photocycles share a structural signaling mechanism and that a particular conserved histidine, previously proposed to be involved in signal propagation, in fact tunes photoresponse.
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3.
  • Logan, Derek, et al. (författare)
  • Status of the crystallography beamlines at the MAX IV Laboratory
  • 2015
  • Ingår i: The European Physical Journal Plus. - : Springer Science and Business Media LLC. - 2190-5444. ; 130:3
  • Forskningsöversikt (refereegranskat)abstract
    • The MAX IV Laboratory in Lund is currently operating two storage rings, the 1.5 GeV MAX II and the 700MeV MAX III, as well as constructing the new facility MAX IV, which will house a 1.5 GeV and a 3 GeV ring. At the MAX II synchrotron there are three hard X-ray beamlines at which crystallography can be performed: I711, I811 and I911. Beamline I711 is mainly used for powder diffraction. I811 is an EXAFS station at which surface XRD can also be carried out. I911 is a beamline with five experimental stations on a single superconducting wiggler source, of which two are currently used for macromolecular crystallography, namely the monochromatic station I911-2 and the tuneable station I911-3, which is equipped with a state-of-the-art goniometer and robotic sample changer. We will give an overview of the capabilities of these beamlines, focusing particularly on the macromolecular crystallography beamline I911 and some recent scientific highlights produced there. We will also give a brief overview of new beamlines for crystallography that are under construction or planned for the MAX IV facility.
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5.
  • Mota-Santiago, Pablo, et al. (författare)
  • In situ biaxial loading and multi-scale deformation measurements of nanostructured materials at the CoSAXS beamline at MAX IV Laboratory
  • 2023
  • Ingår i: Journal of Applied Crystallography. - 0021-8898. ; 56, s. 967-975
  • Tidskriftsartikel (refereegranskat)abstract
    • Characterization of the mechanical response of polymers and composite materials relies heavily on the macroscopic stress-strain response in uniaxial tensile configurations. To provide representative information, the deformation process must be homogeneous within the gauge length, which is a condition that is rarely achieved due to stress concentration or inhomogeneities within the specimen. In this work, the development of a biaxial mechanical testing device at the CoSAXS beamline at MAX IV Laboratory is presented. The design facilitates simultaneous measurement of small- and wide-angle X-ray scattering (SAXS/WAXS), allowing assessment of the microstructural configuration before, after and during the continuous deformation process at multiple length scales. The construction also supports multiple deformation conditions, while guaranteeing stability even at high loads. Furthermore, the mechanical experiments can be complemented with spatially resolved mesoscopic surface deformation measurements using 3D-surface digital image correlation (DIC). Polycarbonate (PC) was used to demonstrate the varied material response to multi-axial deformation, as PC is isotropic with a high glass transition temperature (∼150°) and high strength. As a result, a clear correlation between full-field methods and the microstructural information determined from WAXS measurements is demonstrated. When a uniaxial load is applied, homogeneous strain regions could be observed extending perpendicular to the applied load. When a secondary axial load was added (biaxial mode), it was observed that high strain domains were created near the centre of the sample and at the boundaries after yield. With increased strain, the deformation in the main deformation direction also increases. Mechanical reliability was demonstrated by carrying out static loading of polyacrylonitrile-based carbon fibre (CF) bundles. As a result, the nonlinear stiffening behaviour typically observed in CFs was seen, while no evidence of the creation of new voids during loading was observed. The results support the reliability and broad applicability of the developed technique.
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6.
  • Plivelic, Tomás S., et al. (författare)
  • X-ray tracing, design and construction of an optimized optics scheme for CoSAXS, the small angle x-ray scattering beamline at MAX IV laboratory
  • 2019
  • Ingår i: Proceedings of the 13th International Conference on Synchrotron Radiation Instrumentation, SRI 2018. - : Author(s). - 9780735417823 ; 2054
  • Konferensbidrag (refereegranskat)abstract
    • A novel optical design for a flexible SAXS beamline at a modern synchrotron has been implemented for the CoSAXS beamline at the 3GeV ring at the MAX TV Laboratory. The performance of the beamline has been simulated through combined ray tracing and wave propagation with the code xrt taking into account the low emittance and highly coherent beam of MAX TV and the short inter-optics distances of the beamline. The total photon flux is estimated to be 1012-1013 ph/s with the coherent flux portion up to 10 % at 7.1 keV. The inhomogeneities in the X-ray beam arising from use of real (non-idealised) mirror surfaces are also modelled using the measured slope profiles of the mirrors. Strategies to mitigate these inhomogeneities are discussed. The optical components for CoSAXS have been constructed and beamline commissioning will start in 2019.
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7.
  • Sharma, Amit, et al. (författare)
  • A simple adaptation to a protein crystallography station to facilitate difference X-ray scattering studies
  • 2019
  • Ingår i: Journal of Applied Crystallography. - 1600-5767. ; 52:2, s. 378-386
  • Tidskriftsartikel (refereegranskat)abstract
    • The X-ray crystallography station I911-2 at MAXLab II (Lund, Sweden) has been adapted to enable difference small- and wide-angle X-ray scattering (SAXS/WAXS) data to be recorded. Modifications to the beamline included a customized flow cell, a motorized flow cell holder, a helium cone, a beam stop, a sample stage and a sample delivery system. This setup incorporated external devices such as infrared lasers, LEDs and reaction mixers to induce conformational changes in macromolecules. This platform was evaluated through proof-of-principle experiments capturing light-induced conformational changes in phytochromes. A difference WAXS signature of conformational changes in a plant aquaporin was also demonstrated using caged calcium.
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8.
  • Thunnissen, Marjolein, et al. (författare)
  • BioMAX: The Future Macromolecular Crystallography Beamline at MAX IV
  • 2013
  • Ingår i: 11th International Conference on Synchrotron Radiation Instrumentation (SRI 2012). - : IOP Publishing. - 1742-6596 .- 1742-6588. ; 425
  • Konferensbidrag (refereegranskat)abstract
    • This paper describes the preliminary design of the BioMAX beamline at the 3 GeV ring of the MAX IV facility, focusing on the optics and x-ray beam performance. The MAX IV facility will include two storage rings with 1.5 GeV and 3.0 GeV electron energy and a linac serving both as injector for the two rings and feeding a short pulse facility. BioMAX is one of the first seven beamlines funded at the MAX IV facility. It is a multipurpose high-throughput beamline for macromolecular crystallography. The beamline aims to be robust and simple to operate with a beam benefiting from the properties of the MAX IV 3 GeV ring. However it does not aim at the smallest beam or crystal sizes since it is foreseen that it will be complemented with a microfocus beamline aiming at a beam size of 1 mu m. The beamline experiment setup will be highly automated, both in terms of sample handling hardware and data analysis, including feedback to the data collection. The BioMAX beamline is planned to be in operation in 2016.
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9.
  • Ursby, Thomas, et al. (författare)
  • BioMAX the first macromolecular crystallography beamline at MAX IV Laboratory
  • 2020
  • Ingår i: Journal of Synchrotron Radiation. - Chichester : Wiley-Blackwell. - 0909-0495 .- 1600-5775. ; 27, s. 1415-1429
  • Tidskriftsartikel (refereegranskat)abstract
    • BioMAX is the first macromolecular crystallography beamline at the MAX IV Laboratory 3 GeV storage ring, which is the first operational multi-bend achromat storage ring. Due to the low-emittance storage ring, BioMAX has a parallel, high-intensity X-ray beam, even when focused down to 20 μm × 5 μm using the bendable focusing mirrors. The beam is tunable in the energy range 5-25 keV using the in-vacuum undulator and the horizontally deflecting double-crystal monochromator. BioMAX is equipped with an MD3 diffractometer, an ISARA high-capacity sample changer and an EIGER 16M hybrid pixel detector. Data collection at BioMAX is controlled using the newly developed MXCuBE3 graphical user interface, and sample tracking is handled by ISPyB. The computing infrastructure includes data storage and processing both at MAX IV and the Lund University supercomputing center LUNARC. With state-of-the-art instrumentation, a high degree of automation, a user-friendly control system interface and remote operation, BioMAX provides an excellent facility for most macromolecular crystallography experiments. Serial crystallography using either a high-viscosity extruder injector or the MD3 as a fixed-target scanner is already implemented. The serial crystallography activities at MAX IV Laboratory will be further developed at the microfocus beamline MicroMAX, when it comes into operation in 2022. MicroMAX will have a 1 μm × 1 μm beam focus and a flux up to 1015 photons s with main applications in serial crystallography, room-temperature structure determinations and time-resolved experiments.
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10.
  • Ursby, Thomas, et al. (författare)
  • The macromolecular crystallography beamline I911-3 at the MAX IV laboratory.
  • 2013
  • Ingår i: Journal of Synchrotron Radiation. - 1600-5775. ; 20:Pt 4, s. 648-653
  • Tidskriftsartikel (refereegranskat)abstract
    • The macromolecular crystallography beamline I911-3, part of the Cassiopeia/I911 suite of beamlines, is based on a superconducting wiggler at the MAX II ring of the MAX IV Laboratory in Lund, Sweden. The beamline is energy-tunable within a range between 6 and 18 keV. I911-3 opened for users in 2005. In 2010-2011 the experimental station was completely rebuilt and refurbished such that it has become a state-of-the-art experimental station with better possibilities for rapid throughput, crystal screening and work with smaller samples. This paper describes the complete I911-3 beamline and how it is embedded in the Cassiopeia suite of beamlines.
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