| 1. |
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| 2. |
- 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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| 3. |
- 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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| 4. |
- 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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| 5. |
- Björling, Marcus, et al.
(författare)
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Towards the true prediction of EHL friction
- 2013
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Ingår i: Tribology International. - : Elsevier BV. - 0301-679X .- 1879-2464. ; 66, s. 19-26
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Tidskriftsartikel (refereegranskat)abstract
- The capability to predict elastohydrodynamic film-thickness and friction from primary measurements of transport properties of liquid has been an elusive goal for tribologists for 50 years. Most comparisons between predictions and experiments involve some amount of tuning of the model in order to match the experimental results. In true prediction, this cannot be done since there are normally no experimental results to compare to. Primary measurements of lubricant transport properties of Squalane were performed, and used in a numerical friction prediction model. Afterwards, friction was measured in a ball-on-disc tribotester. No tuning of the lubricant properties, model or test setup were applied. The current work on EHL-friction is therefore a true representation of the current level of EHL-friction prediction.
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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. |
- Fagerberg, Linn, et al.
(författare)
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Contribution of antibody-based protein profiling to the human chromosome-centric proteome project (C-HPP)
- 2013
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Ingår i: Journal of Proteome Research. - : American Chemical Society (ACS). - 1535-3893 .- 1535-3907. ; 12:6, s. 2439-2448
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Tidskriftsartikel (refereegranskat)abstract
- A gene-centric Human Proteome Project has been proposed to characterize the human protein-coding genes in a chromosome-centered manner to understand human biology and disease. Here, we report on the protein evidence for all genes predicted from the genome sequence based on manual annotation from literature (UniProt), antibody-based profiling in cells, tissues and organs and analysis of the transcript profiles using next generation sequencing in human cell lines of different origins. We estimate that there is good evidence for protein existence for 69% (n = 13985) of the human protein-coding genes, while 23% have only evidence on the RNA level and 7% still lack experimental evidence. Analysis of the expression patterns shows few tissue-specific proteins and approximately half of the genes expressed in all the analyzed cells. The status for each gene with regards to protein evidence is visualized in a chromosome-centric manner as part of a new version of the Human Protein Atlas (www.proteinatlas.org).
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| 8. |
- Ji, Cheng, et al.
(författare)
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Crystallography of low Z material at ultrahigh pressure : Case study on solid hydrogen
- 2020
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Ingår i: Matter and Radiation at Extremes. - : American Institute of Physics (AIP). - 2468-2047 .- 2468-080X. ; 5:3
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Tidskriftsartikel (refereegranskat)abstract
- Diamond anvil cell techniques have been improved to allow access to the multimegabar ultrahigh-pressure region for exploring novel phenomena in condensed matter. However, the only way to determine crystal structures of materials above 100 GPa, namely, X-ray diffraction (XRD), especially for low Z materials, remains nontrivial in the ultrahigh-pressure region, even with the availability of brilliant synchrotron X-ray sources. In this work, we perform a systematic study, choosing hydrogen (the lowest X-ray scatterer) as the subject, to understand how to better perform XRD measurements of low Z materials at multimegabar pressures. The techniques that we have developed have been proved to be effective in measuring the crystal structure of solid hydrogen up to 254 GPa at room temperature [C. Ji et al., Nature 573, 558–562 (2019)]. We present our discoveries and experiences with regard to several aspects of this work, namely, diamond anvil selection, sample configuration for ultrahigh-pressure XRD studies, XRD diagnostics for low Z materials, and related issues in data interpretation and pressure calibration. We believe that these methods can be readily extended to other low Z materials and can pave the way for studying the crystal structure of hydrogen at higher pressures, eventually testing structural models of metallic hydrogen.
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| 9. |
- Jirkovský, Jakub S, 1980, et al.
(författare)
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Reduction of Oxygen on Dispersed Nanocrystalline CoS2
- 2012
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 116:46, s. 24436-24444
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Tidskriftsartikel (refereegranskat)abstract
- The electrocatalytic properties of nanocrystalline CoS2 have been investigated for the oxygen reduction reaction (ORR) in 0.1 M HClO4. CoS2 with pyrite structure was prepared by hydrothermal synthesis and attached to a glassy carbon electrode from solution with a mixture of carbon and Nafion. The prepared CoS2 electrode layers showed high activity toward the ORR and very good stability under oxygen reducing conditions. Selectivity of the ORR toward H2O2 was determined by rotating (ring) disk electrode measurements, and relatively high selectivity was obtained with up to 80% H2O2 formation around 0.4 V (vs Ag/AgCl), but this dropped to zero for potentials below 0.0 V. The amount of H2O2 produced between 0.6 and 0.0 V was dependent on the quality of the CoS2 dispersion within the electrode layer, and decreasing CoS2 particle size resulted in significant improvement in the ORR electrocatalytic activity, both by increasing the turnover frequency and through decreasing the selectivity toward H2O2 production.
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| 10. |
- Kahnt, Maik, et al.
(författare)
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Measurement of the coherent beam properties at the CoSAXS beamline
- 2021
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Ingår i: Journal of Synchrotron Radiation. - 0909-0495. ; 28, s. 1948-1953
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Tidskriftsartikel (refereegranskat)abstract
- The CoSAXS beamline at the MAX IV Laboratory is a modern multi-purpose (coherent) small-Angle X-ray scattering (CoSAXS) instrument, designed to provide intense and optionally coherent illumination at the sample position, enabling coherent imaging and speckle contrast techniques. X-ray tracing simulations used to design the beamline optics have predicted a total photon flux of 1012-1013 photons s-1 and a degree of coherence of up to 10% at 7.1 keV. The normalized degree of coherence and the coherent flux of this instrument were experimentally determined using the separability of a ptychographic reconstruction into multiple mutually incoherent modes and thus the Coherence in the name CoSAXS was verified. How the beamline can be used both for coherent imaging and XPCS measurements, which both heavily rely on the degree of coherence of the beam, was demonstrated. These results are the first experimental quantification of coherence properties in a SAXS instrument at a fourth-generation synchrotron light source.
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