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81.
Alloys based on titanium aluminides received a lot of attention because of their capability to substitute Ni-based superalloys in high-temperature applications. However, the phase equilibria between the main microstructure constituents (αTi), (βTi), γ (TiAl) and α2 (Ti3Al) can be shifted significantly by impurities such as oxygen especially at high temperatures. This behavior is investigated on the tie-triangle (αTi) + (βTi) + γ (TiAl) in the ternary Ti-Al-Nb system at 1300 °C. An explanation for this behavior could be the occupation of octahedral voids by impurities in certain phases. 相似文献
82.
Raushan K. Singh Benedikt M. Blossom David A. Russo Ranjitha Singh Høgni Weihe Niels H. Andersen Manish K. Tiwari Poul E. Jensen Claus Felby Morten J. Bjerrum 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(2):454-463
Lytic polysaccharide monooxygenases (LPMOs) are copper-containing enzymes capable of oxidizing crystalline cellulose which have large practical application in the process of refining biomass. The catalytic mechanism of LPMOs still remains debated despite several proposed reaction mechanisms. Here, we report a long-lived intermediate (t1/2=6–8 minutes) observed in an LPMO from Thermoascus aurantiacus (TaLPMO9A). The intermediate with a strong absorption around 420 nm is formed when reduced LPMO-CuI reacts with sub-equimolar amounts of H2O2. UV/Vis absorption spectroscopy, electron paramagnetic resonance, resonance Raman and stopped-flow spectroscopy suggest that the observed long-lived intermediate involves the copper center and a nearby tyrosine (Tyr175). Additionally, activity assays in the presence of sub-equimolar amounts of H2O2 showed an increase in the LPMO oxidation of phosphoric acid swollen cellulose. Accordingly, this suggests that the long-lived copper-dependent intermediate could be part of the catalytic mechanism for LPMOs. The observed intermediate offers a new perspective into the oxidative reaction mechanism of TaLPMO9A and hence for the biomass oxidation and the reactivity of copper in biological systems. 相似文献
83.
Dr. Raju Bej Dr. Chuanxiong Nie Dr. Kai Ludwig Dr. Vahid Ahmadi Dr. Jakob Trimpert Julia M. Adler Dr. Tatyana L. Povolotsky Dr. Katharina Achazi Marten Kagelmacher Ricardo Martin Vidal Dr. Jens Dernedde Dr. Benedikt B. Kaufer Prof. Dr. Rainer Haag 《Angewandte Chemie (International ed. in English)》2023,62(29):e202304010
Mucins are the key component of the defensive mucus barrier. They are extended fibers of very high molecular weight with diverse biological functions depending strongly on their specific structural parameters. Here, we present a mucin-inspired nanostructure, produced via a synthetic methodology to prepare methacrylate-based dendronized polysulfates ( MIP-1 ) on a multi gram-scale with high molecular weight (MW=450 kDa) and thiol end-functionalized mucin-inspired polymer ( MIP ) via RAFT polymerization. Cryo-electron tomography (Cryo-ET) analysis of MIP-1 confirmed a mucin-mimetic wormlike single-chain fiber structure (length=144±59 nm) in aqueous solution. This biocompatible fiber showed promising activity against SARS-CoV-2 and its mutant strain, with a remarkable low half maximal (IC50) inhibitory concentration (IC50=10.0 nM). Additionally, we investigate the impact of fiber length on SARS-CoV-2 inhibition by testing other functional polymers ( MIPs ) of varying fiber lengths. 相似文献
84.
Benedikt Peter Antoine Levrier Prof. Dr. Petra Schwille 《Angewandte Chemie (International ed. in English)》2023,62(17):e202218507
Compartmentalization is key to many cellular processes and a critical bottleneck of any minimal life approach. In cells, a complex chemistry is responsible for bringing together or separating biomolecules at the right place at the right time. Lipids, nucleic acids and proteins self-organize, thereby creating boundaries, interfaces and specialized microenvironments. Exploiting reversible RNA-based liquid-liquid phase separation (LLPS) inside giant unilamellar vesicles (GUVs), we present an efficient system capable of propagating an RNA-based enzymatic reaction across a population of GUVs upon freezing-thawing (FT) temperature cycles. We report that compartmentalization in the condensed RNA-rich phase can accelerate such an enzymatic reaction. In the decondensed state, RNA substrates become homogeneously dispersed, enabling content exchange between vesicles during freeze-thawing. This work explores how a minimal reversible phase separation system in lipid vesicles could help to implement spatiotemporal control in cyclic processes, as required for minimal cells. 相似文献
85.
86.
Benedikt Bergmann Martin Pichotka Stanislav Pospisil Jiri Vycpalek Petr Burian Pavel Broulim Jan Jakubek 《The European Physical Journal C - Particles and Fields》2017,77(6):421
Timepix3 detectors are the latest generation of hybrid active pixel detectors of the Medipix/Timepix family. Such detectors consist of an active sensor layer which is connected to the readout ASIC (application specific integrated circuit), segmenting the detector into a square matrix of 256 \(\times \) 256 pixels (pixel pitch 55 \(\upmu \)m). Particles interacting in the active sensor material create charge carriers, which drift towards the pixelated electrode, where they are collected. In each pixel, the time of the interaction (time resolution 1.56 ns) and the amount of created charge carriers are measured. Such a device was employed in an experiment in a 120 GeV/c pion beam. It is demonstrated, how the drift time information can be used for “4D” particle tracking, with the three spatial dimensions and the energy losses along the particle trajectory (dE/dx). Since the coordinates in the detector plane are given by the pixelation (x,y), the x- and y-resolution is determined by the pixel pitch (55 \(\upmu \)m). A z-resolution of 50.4 \(\upmu \)m could be achieved (for a 500 \(\upmu \)m thick silicon sensor at 130 V bias), whereby the drift time model independent z-resolution was found to be 28.5 \(\upmu \)m. 相似文献
87.
88.
Markus Wieland Armin Benz Benedikt Klauser Jörg S. Hartig Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(15):2715-2718
RNA Lego : The use of natural riboswitch aptamers in synthetic RNA switches (see picture) should broaden the scope of artificial RNA regulators dramatically. It is shown that thiamine pyrophosphate (TPP) aptamers can be used in engineered devices as very sensitive switches of gene expression in unmodified organisms. The approach demonstrates that intrinsic metabolites can be utilized as external effectors of cellular functions.
89.
o-Iodoxybenzoic acid (IBX) was found to mediate the conversion of alpha-alkynyl alcohols into Z-enediones under notably mild conditions via a novel rearrangement mechanism (33-65% yield, 13 examples). 相似文献
90.
Positivity - In this paper we complete the analysis of a statistical mechanics model on Cayley trees of any degree, started in Botirov (Positivity 21(3):955–961, 2017), Eshkabilov et al. (J... 相似文献