| 1. |
- Marçal, L. A.B., et al.
(författare)
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Structural and chemical properties of anion exchanged CsPb(Br(1−x)Cl x )3 heterostructured perovskite nanowires imaged by nanofocused x-rays
- 2024
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Ingår i: Nanotechnology. - 0957-4484. ; 35:26
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Tidskriftsartikel (refereegranskat)abstract
- Over the last years metal halide perovskites have demonstrated remarkable potential for integration in light emitting devices. Heterostructures allow for tunable bandgap depending on the local anion composition, crucial for optoelectronic devices, but local structural effects of anion exchange in single crystals is not fully understood. Here, we investigate how the anion exchange of CsPbBr3 nanowires fully and locally exposed to HCl vapor affects the local crystal structure, using nanofocused x-rays. We study the nanoscale composition and crystal structure as function of HCl exposure time and demonstrate the correlation of anion exchange with changes in the lattice parameter. The local composition was measured by x-ray fluorescence and x-ray diffraction, with general agreement of both methods but with much less variation using latter. The heterostructured nanowires exhibit unintentional gradients in composition, both axially and radially. Ferroelastic domains are observed for all HCl exposure times, and the magnitude of the lattice tilt at the domain walls scales with the Cl concentration.
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| 2. |
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| 3. |
- A. B. Marçal, L., et al.
(författare)
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Spatially resolved structural and chemical properties of the white layer in machined Inconel 718 super alloy
- 2024
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Ingår i: Materials and Design. - 0264-1275. ; 239
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Tidskriftsartikel (refereegranskat)abstract
- Inconel 718 is one type of nickel-based alloy used for a large range of applications, including gas turbines and aeroengines components. Although mechanical and thermodynamic properties of this material have been deeply studied in the past years, a method able to investigate local properties of the thin white layer formed on the alloy surface after machining remains challenging. Here, a 90 nm X-ray beam is used to probe the local strain, crystal orientation, and chemical composition of grains in the white layer. Data reveals mosaicity induced by the tool during machining. The high spatial resolution, combined with crystal lattice sensitivity, shows that the average grain size is around 30 nm throughout the white layer, while the strain is anisotropic nearest to the surface. Results provide new insights on the basic properties of the white layer in super alloys, revealing important information about the impact of finish machining which might help to explain fatigue and cracking formation on these materials during their usage phase.
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| 4. |
- Berntsson, Oskar, 1989, et al.
(författare)
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Sequential conformational transitions and alpha-helical supercoiling regulate a sensor histidine kinase
- 2017
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Sensor histidine kinases are central to sensing in bacteria and in plants. They usually contain sensor, linker, and kinase modules and the structure of many of these components is known. However, it is unclear how the kinase module is structurally regulated. Here, we use nano- to millisecond time-resolved X-ray scattering to visualize the solution structural changes that occur when the light-sensitive model histidine kinase YF1 is activated by blue light. We find that the coiled coil linker and the attached histidine kinase domains undergo a left handed rotation within microseconds. In a much slower second step, the kinase domains rearrange internally. This structural mechanism presents a template for signal transduction in sensor histidine kinases.
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| 5. |
- Björling, Alexander, 1983, et al.
(författare)
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Ubiquitous Structural Signaling in Bacterial Phytochromes
- 2015
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Ingår i: Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 6:17, s. 3379-3383
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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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| 6. |
- Dzhigaev, D, et al.
(författare)
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Three-dimensional coherent x-ray diffraction imaging of ferroelastic domains in single CsPbBr3 perovskite nanoparticles
- 2021
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 23:6
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Tidskriftsartikel (refereegranskat)abstract
- Metal halide perovskites attract significant interest due to their remarkable performance in optoelectronic devices. However, the gap in understanding the relationship between their nanoscale structure and properties limits their application towards novel devices. In this work, twinned ferroelastic domains in single 500 nm CsPbBr3 particles are studied with 3D Bragg coherent x-ray diffraction imaging. A preferential double-domain structure is revealed in four identical particles, with one domain oriented along the [110] and the other along the [002] direction. The particles exhibit similar scattering volume ratios of 0.12 0.026 between twin phases, suggesting the possibility of a deterministic formation process. The domains exhibit a difference in lattice tilt of 0.59 degrees, in excellent agreement with calculations of the lattice mismatch at the (112) twin boundary. These results provide important insights both for the fundamental understanding of ferroelastic nanoscale materials and for the performance improvement of perovskite-based devices. Moreover, this work paves the way towards real-time imaging of the domain dynamics in ferroic systems.
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| 7. |
- Berntsson, Oskar, 1989, et al.
(författare)
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Time-Resolved X-Ray Solution Scattering Reveals the Structural Photoactivation of a Light-Oxygen-Voltage Photoreceptor
- 2017
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Ingår i: Structure. - : Elsevier BV. - 0969-2126. ; 25:6
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Tidskriftsartikel (refereegranskat)abstract
- Light-oxygen-voltage (LOV) receptors are sensory proteins controlling a wide range of organismal adaptations in multiple kingdoms of life. Because of their modular nature, LOV domains are also attractive for use as optogenetic actuators. A flavin chromophore absorbs blue light, forms a bond with a proximal cysteine residue, and induces changes in the surroundings. There is a gap of knowledge on how this initial signal is relayed further through the sensor to the effector module. To characterize these conformational changes, we apply time-resolved X-ray scattering to the homodimeric LOV domain from Bacillus subtilis YtvA. We observe a global structural change in the LOV dimer synchronous with the formation of the chromophore photoproduct state. Using molecular modeling, this change is identified as splaying apart and relative rotation of the two monomers, which leads to an increased separation at the anchoring site of the effector modules.
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| 8. |
- Björling, Alexander, 1983, et al.
(författare)
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Structural photoactivation of a full-length bacterial phytochrome
- 2016
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 2:8
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Tidskriftsartikel (refereegranskat)abstract
- Phytochromes are light sensor proteins found in plants, bacteria, and fungi. They function by converting a photon absorption event into a conformational signal that propagates from the chromophore through the entire protein. However, the structure of the photoactivated state and the conformational changes that lead to it are not known. We report time-resolved x-ray scattering of the full-length phytochrome from Deinococcus radiodurans on micro-and millisecond time scales. We identify a twist of the histidine kinase output domains with respect to the chromophore-binding domains as the dominant change between the photoactivated and resting states. The time-resolved data further show that the structural changes up to the microsecond time scales are small and localized in the chromophore-binding domains. The global structural change occurs within a few milliseconds, coinciding with the formation of the spectroscopic meta-Rc state. Our findings establish key elements of the signaling mechanism of full-length bacterial phytochromes.
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| 9. |
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| 10. |
- Björling, Gunilla, Docent, et al.
(författare)
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Risk Evaluation of Therapy Medical Devices and Implants for Increased Patient Safety : REMISS Horizon 2020 Research and Innovation Action
- 2017
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Konferensbidrag (refereegranskat)abstract
- Current knowledge in the area of medical devices remains insufficiently complete, and many of the established test methods and international standards (ISO (International Organization for Standardization) standards) open up to individual interpretation on how the test should be performed and the results reported. Treating long-term diseases such as cancer imposes a stringent sequence of various treatments on patients. For instance, cancer may be treated with radiation and chemotherapy; the latter in many treatment protocols requiring the implantation of an intravascular catheter during a prolonged period of time. To maximize the effect of such measures, as well as issues related to the patient Health Related Quality of Life (HRQoL), integrated and validated methodologies are needed as decisional basis for appropriate risk management and patient safety with regard to clinical use of intravascular catheters.The ambition of the REMISS project is to: Establish integrated and validated methodologies for risk management of the clinical use of intravascular catheters with respect to the clinical service lifetime, improved patient treatment, safety and HRQoL. This is assumed to reduce patient suffering due to complications associated with material deployment and degradation associated side effects for e.g. cancer patients receiving treatment with chemotherapeutical drugs using an intravascular catheter.The main vision is to improve the standards for eliminating side effects (complications) caused by deployment from and degradation of intravascular catheters, as well as loss of performance due to material-drug-biological system interactions, compared to the current state-of-the-art. Realising the project goals the rate of catheter-associated complications can be lowered by 40-50%, which in turn will improve patient treatment, safety and HRQoL, as well as health care related costs.Package integrally developed methodologies, predictive models, databases, and other project findings, as a potential product with a holistic coverage. It is believed that commercialisation of (selected) results will be the best option in order to create sustainable availability of this service based on continued research on intravascular catheters according to integrated and validated methodologies.REMISS answer the call NMBP-12-2017 Development of a Reliable Methodology for Better Risk Management of Engineered Biomaterials Advanced Therapy Medicinal Products and/or Medical Devices Marcy, P. Central venous access: techniques and indications in oncology. European Society of Radiology, 2008; 18; 2333-44 Maki DG, et al The risk of bloodstream infection in adults with different intravascular devices: a systematic review of 200 published prospective studies. Mayo Clin Proc 2006: 81 (9): 1159-71. Frostell, C., Björling, G., Strömberg, E., Karlsson, S., and Aune, R. E., Tracheal Implants Revisited, The Lancet (2017), 389(10075) pp.1191
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| 11. |
- Björling, Mikael, et al.
(författare)
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An NMR Self-Diffusion Study of the Interaction between Sodium Hyaluronate and Tetradecyltrimethylammonium Bromide
- 1995
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 28:20, s. 6970-6975
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Tidskriftsartikel (refereegranskat)abstract
- A decrease of the NMR self-diffusion coefficient of sodium hyaluronate (NaHy) upon increasing tetradecyltrimethylammonium bromide (TTAB) concentration in 202 mM NaCl (just enough to attain single phase conditions irrespective of the TTAB concentration) is interpreted in terms of the formation of NaHy–TTAB complexes containing several NaHy chains. The complexes are judged to be induced by multiple-site electrostatic condensation of TTAB micelles onto the Hy chains. Thus, the TTAB micelles may act as bridging points between, and within, the NaHy chains. For a 1% wt NaHy solution, at 202 mM NaCl, the fraction of adsorbed TTAB has a maximum at 10 mM TTAB where an estimated 54% of all the added TTAB is bound. At 70 mM TTAB, the fraction of bound TTAB has decreased to 42%. The decrease of the binding constant with increasing TTAB concentration is attributed to a more efficient electrostatic screening; i.e., the ionic strength (due to uncondensed species) increases. The observed NaHy–TTAB complexes are likely to be precursors of the precipitated phase formed at lower salt concentrations.
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| 12. |
- Neckel, Itamar T., et al.
(författare)
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Unveiling Center-Type Topological Defects on Rosettes of Lead Zirconate Titanate Associated to Oxygen Vacancies
- 2021
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Ingår i: Annalen der Physik. - : Wiley. - 0003-3804 .- 1521-3889.
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the formation of topological defects in ferroelectric materials can provide access to their unusual physics, invaluable for possible applications of domain engineering in nanoelectronics. The present study shows the spontaneous formation of center-type topological defects in lead zirconate titanate (PZT) films, characterized by a strong in-plane radial electromechanical response on rosette-like structures, as revealed by piezoelectric response force microscopy. Multi-modal electron and X-ray based techniques provide a comprehensive set of tools for delving at atomic scale the local chemistry, electronic, and crystalline structures. The elemental surface-sensitivity of soft X-ray absorption shows chemical segregation and drastic changes in the titanium electronic structure, which have been associated to oxygen vacancies, leading to a mechanism that describe the polarization symmetry on the rosettes. X-ray nanofluorescence experiments revealed titanium segregation, corroborating with the absorption and low energy electron microscopy images. Taking advantage of a nanobeam, 2D nanodiffraction maps probed the complex microstructure of the domains, revealing its mosaicity and lattice strain at the nanoscale. This study highlights a complex topological structure and provides, by the simultaneous application of a set of analytical tools, a broad comprehension of the formation of center-type ferroelectric topological defects in PZT.
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| 13. |
- Takala, Heikki, et al.
(författare)
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Light-induced structural changes in a monomeric bacteriophytochrome
- 2016
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Ingår i: Structural Dynamics. - : AIP Publishing. - 2329-7778. ; 3:5
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Tidskriftsartikel (refereegranskat)abstract
- Phytochromes sense red light in plants and various microorganism. Light absorption causes structural changes within the protein, which alter its biochemical activity. Bacterial phytochromes are dimeric proteins, but the functional relevance of this arrangement remains unclear. Here, we use time-resolved X-ray scattering to reveal the solution structural change of a monomeric variant of the photosensory core module of the phytochrome from Deinococcus radiodurans. The data reveal two motions, a bend and a twist of the PHY domain with respect to the chromophore-binding domains. Infrared spectroscopy shows the refolding of the PHY tongue. We conclude that a monomer of the phytochrome photosensory core is sufficient to perform the light-induced structural changes. This implies that allosteric cooperation with the other monomer is not needed for structural activation. The dimeric arrangement may instead be intrinsic to the biochemical output domains of bacterial phytochromes. © Author(s) 2016.
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| 14. |
- Takala, Heikki, et al.
(författare)
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Signal amplification and transduction in phytochrome photosensors
- 2014
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 509:7499, s. 245-248
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Tidskriftsartikel (refereegranskat)abstract
- Sensory proteins must relay structural signals from the sensory site over large distances to regulatory output domains. Phytochromes are a major family of red-light-sensing kinases that control diverse cellular functions in plants, bacteria and fungi(1-9). Bacterial phytochromes consist of a photosensory core and a carboxy-terminal regulatory domain(10,11). Structures of photosensory cores are reported in the resting state(12-18) and conformational responses to light activation have been proposed in the vicinity of the chromophore(19-23). However, the structure of the signalling state and the mechanism of downstream signal relay through the photosensory core remain elusive. Here we report crystal and solution structures of the resting and activated states of the photosensory core of the bacteriophytochrome from Deinococcus radiodurans. The structures show an open and closed form of the dimeric protein for the activated and resting states, respectively. This nanometre-scale rearrangement is controlled by refolding of an evolutionarily conserved 'tongue', which is in contact with the chromophore. The findings reveal an unusual mechanism in which atomic-scale conformational changes around the chromophore are first amplified into ana angstrom-scale distance change in the tongue, and further grow into a nanometre-scale conformational signal. The structural mechanism is a blueprint for understanding how phytochromes connect to the cellular signalling network.
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| 15. |
- Björling, Alexander, et al.
(författare)
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Chemical Limits on X-ray Nanobeam Studies in Water
- 2023
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Ingår i: Journal of Physical Chemistry C. - 1932-7447. ; 127:28, s. 13877-13885
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Tidskriftsartikel (refereegranskat)abstract
- Operando X-ray studies of chemical reactions have gained increasing interest lately, fueled by the emergence of a new generation of powerful focused X-ray sources. Although it is well known that ionizing radiation causes damage to samples via radical chemistry, this effect is often overlooked in studies of working devices or catalysts where intense focused beams are used as nanoscale probes. Here, we show how an X-ray nanobeam directly causes a phase transition in shape-controlled Pd nanoparticles and that a large oxidative potential must be applied to counteract the effect. In addition, we present a chemical reaction-diffusion model that offers a plausible qualitative explanation of the observations, and which also suggests that prohibitive concentrations of reactive species will arise under any focused X-ray probe, calling into question the validity of these methods as applied to aqueous chemical and catalytic systems.
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| 16. |
- Björling, Alexander, et al.
(författare)
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Three-Dimensional Coherent Bragg Imaging of Rotating Nanoparticles
- 2020
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Ingår i: Physical Review Letters. - : AMER PHYSICAL SOC. - 0031-9007 .- 1079-7114. ; 125:24
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Tidskriftsartikel (refereegranskat)abstract
- Bragg coherent diffraction imaging is a powerful strain imaging tool, often limited by beam-induced sample instability for small particles and high power densities. Here, we devise and validate an adapted diffraction volume assembly algorithm, capable of recovering three-dimensional datasets from particles undergoing uncontrolled and unknown rotations. We apply the method to gold nanoparticles which rotate under the influence of a focused coherent x-ray beam, retrieving their three-dimensional shapes and strain fields. The results show that the sample instability problem can be overcome, enabling the use of fourth generation synchrotron sources for Bragg coherent diffraction imaging to their full potential.
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| 17. |
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| 18. |
- Björling, Gunilla, Docent, et al.
(författare)
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A retrospective survey of outpatients with long-term tracheostomy
- 2006
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Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley-Blackwell. - 0001-5172 .- 1399-6576. ; 50:4, s. 399-406
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Tidskriftsartikel (refereegranskat)abstract
- Background: The Respiratory Unit (RU) at Danderyd University Hospital opened in 1982, with the expressed goal of supporting outpatients with long-term tracheostomy. The primary aim of this retrospective study in tracheostomized patients was to compare the need for hospital care in the 2-year period before and after the tracheostomy.Methods: Data were collected from patient medical records at the RU, from the National Board of Health and Welfare, Sweden and from the Official Statistics of Sweden. The subjects were RU patients in 1982 (Group 1, n = 27) and in 1997 (Group 2, n = 106) with long-term tracheostomy surviving at least 4 years after the tracheostomy.Results: Both groups had few and unchanged needs for hospital care after tracheostomy. They spent ≥ 96% of their time out of hospital. In 1997, (group 2) the number of patients, diagnoses and need for home mechanical ventilation had increased. Life expectancy was assessed for patients in Group 1. Data showed that they lived as long as an age-matched and gender-adjusted control cohort.Conclusions: Long-term tracheostomy may not increase the need for hospital care and does not reduce life expectancy. These clinical observations were made in a setting where patients had regular access to a dedicated outpatient unit.
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| 19. |
- Björling, G., et al.
(författare)
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Moderna antipsykotika ger färre biverkningar och lägre dödlighet: Men de är dyrare än äldre neuroleptika, visar studie från Västra Götaland
- 2012
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Ingår i: Läkartidningen. - 0023-7205 .- 1652-7518. ; 109:29-31, s. 1350-1353
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Västra Götalandsregionen har drygt 1,5 miljoner invåna re. Patienter med diagnosen schizofreni (N = 4 593) under juli 2005 till och med decem ber 2009 har studerats. Läkemedelskostnaden var lägre för äldre neuroleptika än för nyare »atypiska« anti psykotika. Sjukhuskostna derna var lika för båda grup perna, medan öppenvårds kostnaderna var högre vid behandling med nya medel än med äldre. Totalkostnaden per patient varierade från 243 000 (äldre läkemedel) till 360 000 kro nor (nyare antipsykotika). Samsjukligheten tenderade att vara lägre för aripiprazol, men var lika för äldre och and ra nyare preparat. Sjukskrivningstiderna var lika oberoende av preparat. Dödligheten var 2,4 gånger högre hos schizofrenipatien ter än i totalbefolkningen, men den var inte signifikant lägre vid läkemedelsbehand ling än utan. Dock var den signifikant lägre vid behand ling med nyare antipsykotika än med äldre läkemedel.
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| 20. |
- Björling, Marcus, et al.
(författare)
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The correlation between gear contact friction and ball on disc friction measurements
- 2015
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Ingår i: Tribology International. - : Elsevier BV. - 0301-679X .- 1879-2464. ; 83, s. 114-119
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Tidskriftsartikel (refereegranskat)abstract
- Running experiments with full-size gearboxes from the actual application has the advantage of giving realistic results in terms of power losses. The drawback is extensive costs, lengthy testing, and the difficulty in differentiating between load dependent and load independent losses, and which losses are coming from the gears, seals, bearings or synchronizers. In this work, the correlation between friction measurements conducted in a ball-on-disc machine and friction measurements conducted in a back-to-back gear rig is investigated. The correlation between the gear tests and the ball-on-disc tests were reasonably good in terms of absolute values, and the shape of the friction curves were similar, indicating that the ball-on-disc measurements to a large extent are capturing the behavior of the gear contact
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| 21. |
- Cousseau, T., et al.
(författare)
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Film thickness in a ball-on-disc contact lubricated with greases, bleed oils and base oils
- 2012
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Ingår i: Tribology International. - : Elsevier BV. - 0301-679X .- 1879-2464. ; 53, s. 53-60
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Tidskriftsartikel (refereegranskat)abstract
- Three different lubricating greases and their bleed and base oils were compared in terms of film thickness in a ball-on-disc test rig through optical interferometry. The theoretical values calculated according to Hamrock's equation are in close agreement with the base oil film thickness measurements, which validates the selected experimental methodology.The grease and bleed oil film thickness under fully flooded lubrication conditions presented quite similar behaviour and levels. Therefore, the grease film thickness under full film conditions might be predicted using their bleed oil properties, namely the viscosity and pressure-viscosity coefficient. The base and bleed oil lubricant parameter LP are proportional to the measured film thickness.A relationship between grease and the corresponding bleed oil film thickness was evidenced
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| 22. |
- Estévez Mauriz, Laura, 1982, et al.
(författare)
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The livability of spaces: Performance and/or resilience? Reflections on the effects of spatial heterogeneity in transport and energy systems and the implications on urban environmental quality
- 2017
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Ingår i: International Journal of Sustainable Built Environment. - : Elsevier BV. - 2212-6090 .- 2212-6104. ; 6:1, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Cities can be seen as systems of organized complexity formed by interrelated and highly dynamic sub-systems. This paper reflects on the interactions and tensions between socio-ecological and/or socio-technical sub-systems in cities and their capacity to either improve or block urban processes. In this context, spatial heterogeneity could enhance or hinder the performance and resilience of critical urban sub-systems such as transport and energy. The consequence of this interaction might be detrimental to environmental quality (air and acoustic) and the livability of urban areas. This rationale may improve political and expert decision-making processes toward sustainable, resilient and livable cities.
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| 23. |
- Fonseca, Jimeno A., et al.
(författare)
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Spatial heterogeneity for environmental performance and resilient behavior in energy and transportation systems
- 2017
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Ingår i: Computers, Environment and Urban Systems. - : Elsevier BV. - 0198-9715. ; 62, s. 136-145
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes an assessment of the effects of spatial heterogeneity on the future performance and resilience of an urban area. For this, indicators of environmental performance and resilience of critical infrastructures (energy and transportation systems) are explored. The approach combines established methododologies of building performance simulation, energy systems analysis, and environmental impact assessment of buildings and transportation systems. The study is centered on future urban design scenarios for an industrial neighborhood in Switzerland. For this case study, multi-functionality is proportional to the performance and resilience of critical infrastructures. Mono-functionality improves the resilience and performance of energy systems with a negative effect on that of transportation systems. Building intensity, and resource intensive users were found to play a higher role into the future performance and resilience of the area. The findings of this research could complement planning approaches of sustainable and resilient urban areas.
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| 24. |
- Hammarberg, Susanna, et al.
(författare)
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Fast nanoscale imaging of strain in a multi-segment heterostructured nanowire with 2D Bragg ptychography
- 2024
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Ingår i: Journal of Applied Crystallography. - 0021-8898. ; 57, s. 60-70
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Tidskriftsartikel (refereegranskat)abstract
- Developing semiconductor devices requires a fast and reliable source of strain information with high spatial resolution and strain sensitivity. This work investigates the strain in an axially heterostructured 180 nm-diameter GaInP nanowire with InP segments of varying lengths down to 9 nm, simultaneously probing both materials. Scanning X-ray diffraction (XRD) is compared with Bragg projection ptychography (BPP), a fast single-projection method. BPP offers a sufficient spatial resolution to reveal fine details within the largest segments, unlike scanning XRD. The spatial resolution affects the quantitative accuracy of the strain maps, where BPP shows much-improved agreement with an elastic 3D finite element model compared with scanning XRD. The sensitivity of BPP to small deviations from the Bragg condition is systematically investigated. The experimental confirmation of the model suggests that the large lattice mismatch of 1.52% is accommodated without defects.
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| 25. |
- Kampf, C., et al.
(författare)
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Antibody-based tissue profiling as a tool for clinical proteomics
- 2004
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Ingår i: Clinical Proteomics. - 1542-6416 .- 1559-0275. ; 1:3-4, s. 285-299
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Tidskriftsartikel (refereegranskat)abstract
- Here, we show a strategy for high-throughput antibody-based tissue profiling with the aim to create an atlas of protein expression patterns in normal human tissues and cancer tissues representing the 20 most prevalent cancer types. A set of standardized tissue microarrays (TMAs) was produced to allow for rapid screening of a multitude of different cells and tissues using immunohistochemistry. Eight TMA blocks were produced containing 48 different normal human tissues in triplicate and cancer tissue from 216 individually different tumors in duplicate. Sections from these blocks were immunohistochemically stained using five commercial and five in-house generated antibodies. Digital images for annotation of expression profiles were generated using a semiautomated approach. Five hundred seventy-six images and annotation data corresponding to a total of 30 Gbytes of data were collected for each antibody. The data presented here suggest that antibody-based profiling of protein expression in tissues can be used as a valuable tool in clinical proteomics.
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| 26. |
- Marçal, Lucas A.B., et al.
(författare)
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In Situ Imaging of Ferroelastic Domain Dynamics in CsPbBr3Perovskite Nanowires by Nanofocused Scanning X-ray Diffraction
- 2020
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 14:11, s. 15973-15982
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Tidskriftsartikel (refereegranskat)abstract
- The interest in metal halide perovskites has grown as impressive results have been shown in solar cells, light emitting devices, and scintillators, but this class of materials have a complex crystal structure that is only partially understood. In particular, the dynamics of the nanoscale ferroelastic domains in metal halide perovskites remains difficult to study. An ideal in situ imaging method for ferroelastic domains requires a challenging combination of high spatial resolution and long penetration depth. Here, we demonstrate in situ temperature-dependent imaging of ferroelastic domains in a single nanowire of metal halide perovskite, CsPbBr3. Scanning X-ray diffraction with a 60 nm beam was used to retrieve local structural properties for temperatures up to 140 °C. We observed a single Bragg peak at room temperature, but at 80 °C, four new Bragg peaks appeared, originating in different real-space domains. The domains were arranged in periodic stripes in the center and with a hatched pattern close to the edges. Reciprocal space mapping at 80 °C was used to quantify the local strain and lattice tilts, revealing the ferroelastic nature of the domains. The domains display a partial stability to further temperature changes. Our results show the dynamics of nanoscale ferroelastic domain formation within a single-crystal perovskite nanostructure, which is important both for the fundamental understanding of these materials and for the development of perovskite-based devices.
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| 27. |
- Marçal, Lucas A.B., et al.
(författare)
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Inducing ferroelastic domains in single-crystal CsPbBr3 perovskite nanowires using atomic force microscopy
- 2021
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Ingår i: Physical Review Materials. - 2475-9953. ; 5:6
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Tidskriftsartikel (refereegranskat)abstract
- Ferroelectric and ferroelastic domains have been predicted to enhance metal halide perovskite (MHP) solar cell performance. While the formation of such domains can be modified by temperature, pressure, or strain, established methods lack spatial control at the level of single domains. Here, we induce the formation of ferroelastic domains in CsPbBr3 nanowires at room temperature using an atomic force microscope (AFM) tip and visualize the domains using nanofocused x-ray diffraction with a 60 nm beam. Regions scanned with a low AFM tip force show orthorhombic 004 reflections along the nanowire axis, while regions exposed to higher forces exhibit 220 reflections. The applied stress locally changes the crystal structure, leading to lattice tilts that define ferroelastic domains, which spread spatially and terminate at {112}-type domain walls. The ability to induce individual ferroelastic domains within MHPs using AFM gives new possibilities for device design and fundamental experimental studies.
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| 28. |
- Moberg, Christina, et al.
(författare)
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De unga gör helt rätt när de stämmer staten
- 2022
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Ingår i: Aftonbladet. - 1103-9000.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- 1 620 forskare och lärare i forskarvärlden: Vi ställer oss bakom Auroras klimatkrav
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| 29. |
- Nimmrich, Amke, 1995, et al.
(författare)
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Solvent-Dependent Structural Dynamics in the Ultrafast Photodissociation Reaction of Triiodide Observed with Time-Resolved X-ray Solution Scattering
- 2023
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 145:29, s. 15754-15765
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Tidskriftsartikel (refereegranskat)abstract
- Resolving the structural dynamics of bond breaking, bond formation, and solvation is required for a deeper understanding of solutionphase chemical reactions. In this work, we investigate the photodissociation of triiodide in four solvents using femtosecond time-resolved X-ray solution scattering following 400 nm photoexcitation. Structural analysis of the scattering data resolves the solvent-dependent structural evolution during the bond cleavage, internal rearrangements, solvent-cage escape, and bond reformation in real time. The nature and structure of the reaction intermediates during the recombination are determined, elucidating the full mechanism of photodissociation and recombination on ultrafast time scales. We resolve the structure of the precursor state for recombination as a geminate pair. Further, we determine the size of the solvent cages from the refined structures of the radical pair. The observed structural dynamics present a comprehensive picture of the solvent influence on structure and dynamics of dissociation reactions.
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| 30. |
- Reimers, Sonka, et al.
(författare)
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Defect-driven antiferromagnetic domain walls in CuMnAs films
- 2022
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Efficient manipulation of antiferromagnetic (AF) domains and domain walls has opened up new avenues of research towards ultrafast, high-density spintronic devices. AF domain structures are known to be sensitive to magnetoelastic effects, but the microscopic interplay of crystalline defects, strain and magnetic ordering remains largely unknown. Here, we reveal, using photoemission electron microscopy combined with scanning X-ray diffraction imaging and micromagnetic simulations, that the AF domain structure in CuMnAs thin films is dominated by nanoscale structural twin defects. We demonstrate that microtwin defects, which develop across the entire thickness of the film and terminate on the surface as characteristic lines, determine the location and orientation of 180∘ and 90∘ domain walls. The results emphasize the crucial role of nanoscale crystalline defects in determining the AF domains and domain walls, and provide a route to optimizing device performance.
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| 31. |
- Reimers, Sonka, et al.
(författare)
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Defect-driven antiferromagnetic domain walls in CuMnAs films
- 2023
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Ingår i: 2023 IEEE International Magnetic Conference - Short Papers, INTERMAG Short Papers 2023 - Proceedings. - 9798350338362
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Konferensbidrag (refereegranskat)abstract
- Antiferromagnetic (AF) materials offer a route to realising high-speed, high-density data storage devices that are robust against magnetic fields due to their intrinsic dynamics in the THz-regime and the lack magnetic stray fields. The key to functionality and efficiency is the control of AF domains and domain walls. Although AF domain structures are known to be sensitive to magnetoelastic effects, the microscopic interplay of crystalline defects, strain and magnetic ordering remains largely unknown. Here, we reveal, using photoemission electron microscopy combined with scanning x-ray diffraction microscopy and micromagnetic simulations, that the AF domain structure in CuMnAs thin films is dominated by nanoscale structural twin defects, which determine the location and orientation of 180° and 90° domain walls. The results emphasise the high sensitivity of the AF domain structure to the crystallographic nanostructure and provide a route to optimisng device performance.
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| 32. |
- Takala, Heikki, et al.
(författare)
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Light-induced Changes in the Dimerization Interface of Bacteriophytochromes.
- 2015
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Ingår i: The Journal of biological chemistry. - 1083-351X. ; 290:26, s. 16383-92
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Tidskriftsartikel (refereegranskat)abstract
- Phytochromes are dimeric photoreceptor proteins that sense red light levels in plants, fungi, and bacteria. The proteins are structurally divided into a light-sensing photosensory module consisting of PAS, GAF, and PHY domains and a signaling output module, which in bacteriophytochromes typically is a histidine kinase (HK) domain. Existing structural data suggest that two dimerization interfaces exist between the GAF and HK domains, but their functional roles remain unclear. Using mutational, biochemical, and computational analyses of the Deinococcus radiodurans phytochrome, we demonstrate that two dimerization interfaces between sister GAF and HK domains stabilize the dimer with approximately equal contributions. The existence of both dimerization interfaces is critical for thermal reversion back to the resting state. We also find that a mutant in which the interactions between the GAF domains were removed monomerizes under red light. This implies that the interactions between the HK domains are significantly altered by photoconversion. The results suggest functional importance of the dimerization interfaces in bacteriophytochromes.
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| 33. |
- Tjernberg, L O, et al.
(författare)
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Amyloid beta-peptide polymerization studied using fluorescence correlation spectroscopy
- 1999
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Ingår i: Chemistry and Biology. - 1074-5521 .- 1879-1301. ; 6:1, s. 53-62
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Tidskriftsartikel (refereegranskat)abstract
- Background: The accumulation of fibrillar deposits of amyloid beta-peptide (A beta) in brain parenchyma and cerebromeningeal blood vessels is a key step in the pathogenesis of Alzheimer's disease. In this report, polymerization of A beta was studied using fluorescence correlation spectroscopy (FCS), a technique capable of detecting small molecules and large aggregates simultaneously in solution. Results: The polymerization of A beta dissolved in Tris-buffered saline, pH 7.4, occurred above a critical concentration of 50 mu M and proceeded from monomers/dimers into two discrete populations of large aggregates, without any detectable amount of oligomers. The aggregation showed very high cooperativity and reached a maximum after 40 min, followed by an increase in the amount of monomers/dimers and a decrease in the size of the large aggregates. Electron micrographs of samples prepared at the time for maximum aggregation showed a mixture of an amorphous network and short diffuse fibrils, whereas only mature amyloid fibrils were detected after one day of incubation. The aggregation was reduced when A beta was incubated in the presence of A beta ligands, oligopeptides previously shown to inhibit fibril formation, and aggregates were partly dissociated after the addition of the ligands. Conclusions: The polymerization of A beta is a highly cooperative process in which the formation of very large aggregates precedes the formation of fibrils. The entire process can be inhibited and, at least in early stages, partly reversed by A beta ligands.
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