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- Park, Hyung Joo, et al.
(author)
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Toward unsupervised single-shot diffractive imaging of heterogeneous particles using X-ray free-electron lasers
- 2013
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In: Optics Express. - 1094-4087. ; 21:23, s. 28729-28742
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Journal article (peer-reviewed)abstract
- Single shot diffraction imaging experiments via X-ray free-electron lasers can generate as many as hundreds of thousands of diffraction patterns of scattering objects. Recovering the real space contrast of a scattering object from these patterns currently requires a reconstruction process with user guidance in a number of steps, introducing severe bottlenecks in data processing. We present a series of measures that replace user guidance with algorithms that reconstruct contrasts in an unsupervised fashion. We demonstrate the feasibility of automating the reconstruction process by generating hundreds of contrasts obtained from soot particle diffraction experiments.
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| 3. |
- Park, Kwang-Hyun, et al.
(author)
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Tetrameric architecture of an active phenol-bound form of the AAA(+) transcriptional regulator DmpR
- 2020
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In: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 11:1
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Journal article (peer-reviewed)abstract
- The Pseudomonas putida phenol-responsive regulator DmpR is a bacterial enhancer binding protein (bEBP) from the AAA+ ATPase family. Even though it was discovered more than two decades ago and has been widely used for aromatic hydrocarbon sensing, the activation mechanism of DmpR has remained elusive. Here, we show that phenol-bound DmpR forms a tetramer composed of two head-to-head dimers in a head-to-tail arrangement. The DmpR-phenol complex exhibits altered conformations within the C-termini of the sensory domains and shows an asymmetric orientation and angle in its coiled-coil linkers. The structural changes within the phenol binding sites and the downstream ATPase domains suggest that the effector binding signal is propagated through the coiled-coil helixes. The tetrameric DmpR-phenol complex interacts with the σ54 subunit of RNA polymerase in presence of an ATP analogue, indicating that DmpR-like bEBPs tetramers utilize a mechanistic mode distinct from that of hexameric AAA+ ATPases to activate σ54-dependent transcription.
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- Wang, Yong
(author)
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Evolution of the Non-Metallic Inclusions Influenced by Slag-Metal Reactions in Ti-containing Ferritic Stainless Steel
- 2021
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Journal article (other academic/artistic)abstract
- Laboratory experiment and thermodynamic calculation for the Ti-containing 24 mass pct Cr ferriticstainless steel with a CaO-SiO2-Al2O3-MgO system slag were performed to investigate the effect of slagaddition on the inclusion characteristics in molten steel. The morphology, composition, and size evolution of inclusions in steel samples were analyzed in three-dimensional by the electrolytic extraction method and in two-dimensional by the automatic analysis method. The results showed that the Ti content significantly decreased after the slag addition. However, the change of the Si content showed an opposite tendency. The decrease of the Ti content in steel was due to the reduction of SiO2and Al2O3 in the slag by dissolved Ti in steel. An increase of the TiO2 content in the slag can decrease the Ti loss in steel based on the slag-steel kinetic analysis. The total O content in the steel melt decreased from 62 ppm to 26 ppm, and the steel cleanliness was improved, since the number density of inclusions decreased after the slag refining. The results of a kinetic analysis showed that the rate-determining step of the oxidation of Ti in the steel and the reduction of SiO2 in the slag were the mass transfer on the slag side. Also, high Ti2O3-containing inclusions were found to be transformed to Cr2O3-Ti2O3-Al2O3and Cr2O3-Ti2O3-SiO2 system inclusions after the slag addition. The Al2O3 contents in inclusions increased while the Ti2O3 contents decreased with time. However, there were some amount of high-melting-point inclusions with high Al2O3 content, which were not what we expected. When plotted on logarithmic scales, the mole ratio values of the inclusions were expressed as a linear function of the values of the steel melts with a slope of unity, which was theoretically expected.
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