| 1. |
- Ekeberg, Tomas, 1983-, et al.
(författare)
-
Three-dimensional structure determination with an X-ray laser
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Three-dimensional structure determination of a non-crystalline virus has been achieved from a set of randomly oriented continuous diffraction patterns captured with an X-ray laser. Intense, ultra-short X-ray pulses intercepted a beam of single mimivirus particles, producing single particle X-ray diffraction patterns that are assembled into a three-dimensional amplitude distribution based on statistical consistency. Phases are directly retrieved from the assembled Fourier distribution to synthesize a three-dimensional image. The resulting electron density reveals a pseudo-icosahedral asymmetric virion structure with a compartmentalized interior, within which the DNA genome occupies only about a fifth of the volume enclosed by the capsid. Additional electron microscopy data indicate the genome has a chromatin-like fiber structure that has not previously been observed in a virus.
|
|
| 2. |
- Hantke, Max Felix, 1984-
(författare)
-
Coherent Diffractive Imaging with X-ray Lasers
- 2016
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The newly emerging technology of X-ray free-electron lasers (XFELs) has the potential to revolutionise molecular imaging. XFELs generate very intense X-ray pulses and predictions suggest that they may be used for structure determination to atomic resolution even for single molecules. XFELs produce femtosecond pulses that outrun processes of radiation damage and permit the study of structures at room temperature and of structural dynamics.While the first demonstrations of flash X-ray diffractive imaging (FXI) on biological particles were encouraging, they also revealed technical challenges. In this work we demonstrated how some of these challenges can be overcome. We exemplified, with heterogeneous cell organelles, how tens of thousands of FXI diffraction patterns can be collected, sorted, and analysed in an automatic data processing pipeline. We improved image resolution and reduced problems with missing data. We validated, described, and deposited the experimental data in the Coherent X-ray Imaging Data Bank.We demonstrated that aerosol injection can be used to collect FXI data at high hit ratios and with low background. We reduced problems with non-volatile sample contaminants by decreasing aerosol droplet sizes from ~1000 nm to ~150 nm. We achieved this by adapting an electrospray aerosoliser to the Uppsala sample injector. Mie scattering imaging was used as a diagnostic tool to measure positions, sizes, and velocities of individual injected particles.XFEL experiments generate large amounts of data at high rates. Preparation, execution, and data analysis of these experiments benefits from specialised software. In this work we present new open-source software tools that facilitates prediction, online-monitoring, display, and pre-processing of XFEL diffraction data.We hope that this work is a valuable contribution in the quest of transitioning FXI from its first experimental demonstration into a technique that fulfills its potentials.
|
|
| 3. |
- Ortiz, Carlos, 1976-, et al.
(författare)
-
Radiation damage in covalent solids by intense ultra-short soft X-ray pulses
-
Annan publikation (populärvet., debatt m.m.)abstract
- Through irradiation with intense femtosecond soft X-ray pulses the structural damage originating from ultra-fast non-thermal phase transitions is observed. A computational model which combines electronic structure theory with molecular dynamics (MD) for the atomic motion is extended to include interactions relevant at soft X-ray wavelengths (6-13.5 nm). Dedicated Boltzmann transport equation is derived, with electron relaxation rates calculated from density functional theory and energy loss function from binary encounter theory. Preliminary results for diamond are presented and compared to the earlier predictions from MD simulations
|
|
| 4. |
- Schroer, Christian G., et al.
(författare)
-
PETRA IV : the ultralow-emittance source project at DESY
- 2018
-
Ingår i: Journal of Synchrotron Radiation. - 0909-0495. ; 25:5, s. 1277-1290
-
Tidskriftsartikel (refereegranskat)abstract
- The PETRA IV project aims at upgrading the present synchrotron radiation source PETRA III at DESY into an ultralow-emittance source. Being diffraction limited up to X-rays of about 10 keV, PETRA IV will be ideal for three-dimensional X-ray microscopy of biological, chemical and physical processes under realistic conditions at length scales from atomic dimensions to millimetres and time scales down to the sub-nanosecond regime. In this way, it will enable groundbreaking studies in many fields of science and industry, such as health, energy, earth and environment, mobility and information technology. The science case is reviewed and the current state of the conceptual design is summarized, discussing a reference lattice, a hybrid multi-bend achromat with an interleaved sextupole configuration based on the ESRF-EBS design, in more detail as well as alternative lattice concepts.
|
|
