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991.
Asymmetric first‐order transition and interlocked particle state in magnetocaloric La(Fe,Si)13
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Anja Waske Lars Giebeler Bruno Weise Alexander Funk Manuel Hinterstein Markus Herklotz Konstantin Skokov Sebastian Fähler Oliver Gutfleisch Jürgen Eckert 《固体物理学:研究快报》2015,9(2):136-140
In‐situ synchrotron XRD measurements of the magnetocaloric material LaFe11.8Si1.2 are used to understand virgin effects and asymmetry of the underlying first order magnetovolume transition. A remarkable change of the transition kinetics occurs after the first cycle, which we attribute to the formation of cracks originating from the volume change. Tomographic imaging revealed that the bulk material disintegrates via an interlocked state where fragments are loosely connected. Though cracks have opened between the fragments, the transition is sharp, which we attribute to magnetostatic interactions. In the cycled sample we find a strong asymmetry between the transition interval upon heating and cooling, which we explain by isostatic pressure acting on parts of the sample during the cooling transition. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
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Stephan Faust Martin Goschütz Sebastian A. Kaiser Thomas Dreier Christof Schulz 《Applied physics. B, Lasers and optics》2014,116(1):183-194
Single crystal of La3Ga5.5Ta0.5O14 (LGT) containing intentionally 0.5 % of Ho3+ and 1 % of Yb3+ was grown by the Czochralski method. Examination of chemical composition of the grown crystal revealed that luminescent holmium and ytterbium ions are preferably retained in the melt and their actual concentrations are 0.12 and 0.24 %, respectively. Spectroscopic investigation performed encompassed IR host absorption spectra and Raman spectra at room temperature, optical absorption and luminescence spectra of Ho3+ and Yb3+ at room temperature and at 5 K, and luminescence decay curves at room temperature. It was found that all spectral bands recorded show important inhomogeneous line broadening. This feature was attributed to structural disorder inherent to the crystal lattice in which pentavalent Ta5+ ions occupy octahedral Ga(1) sites together with trivalent Ga3+ ions. Despite small concentrations of luminescent ions, the occurrence of nonradiative interaction that feeds the 5I6 and 5I7 levels of Ho3+ ions by transfer of an excitation from the 2F5/2 level of Yb3+ ions was evidenced. Based on examination of spectroscopic parameters evaluated, it was concluded that LGT:Ho, Yb may be considered as a potential intermediate-gain laser active material able to emit infrared radiation from the 5I7 → 5I8 transition of Ho3+ around 2 micrometres upon laser-diode pumping into Yb3+ absorption band. 相似文献
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Self‐Assembled Cyclic d,l‐α‐Peptides as Generic Conformational Inhibitors of the α‐Synuclein Aggregation and Toxicity: In Vitro and Mechanistic Studies
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Dr. Marina Chemerovski‐Glikman Eva Rozentur‐Shkop Dr. Michal Richman Dr. Asaf Grupi Asaf Getler Prof. Haim Y. Cohen Dr. Hadassa Shaked Cecilia Wallin Dr. Sebastian K. T. S. Wärmländer Prof. Elisha Haas Prof. Astrid Gräslund Prof. Jordan H. Chill Prof. Shai Rahimipour 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(40):14236-14246
Many peptides and proteins with large sequences and structural differences self‐assemble into disease‐causing amyloids that share very similar biochemical and biophysical characteristics, which may contribute to their cross‐interaction. Here, we demonstrate how the self‐assembled, cyclic d,l ‐α‐peptide CP‐2 , which has similar structural and functional properties to those of amyloids, acts as a generic inhibitor of the Parkinson′s disease associated α‐synuclein (α‐syn) aggregation to toxic oligomers by an ?off‐pathway“ mechanism. We show that CP‐2 interacts with the N‐terminal and the non‐amyloid‐β component region of α‐syn, which are responsible for α‐syn′s membrane intercalation and self‐assembly, thus changing the overall conformation of α‐syn. CP‐2 also remodels α‐syn fibrils to nontoxic amorphous species and permeates cells through endosomes/lysosomes to reduce the accumulation and toxicity of intracellular α‐syn in neuronal cells overexpressing α‐syn. Our studies suggest that targeting the common structural conformation of amyloids may be a promising approach for developing new therapeutics for amyloidogenic diseases. 相似文献
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Sebastian Korff 《Physik in unserer Zeit》2011,42(4):203-204
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Chemoenzymatic Synthesis of Nonasulfated Tetrahyaluronan with a Paramagnetic Tag for Studying Its Complex with Interleukin‐10
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Sebastian Köhling Georg Künze Katharina Lemmnitzer Dr. Marcel Bermudez Prof. Dr. Gerhard Wolber Dr. Jürgen Schiller Prof. Dr. Daniel Huster Prof. Dr. Jörg Rademann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(16):5563-5574
Implants and artificial biomaterials containing sulfated hyaluronans have been shown to improve the healing of injured skin and bones. It is hypothesized that these effects are mediated by the binding of sulfated glycosaminoglycans (GAGs) to growth factors and cytokines, resulting in the sequestering of proteins to the wound healing site and in modulated protein activity. Given that no direct synthetic access to sulfated oligohyaluronans has been available, little is known about their protein binding and the structure of the resulting protein complexes. Here, the chemoenzymatic preparation of oligohyaluronans on the gram scale is described. Oligohyaluronans are converted into anomeric azides at the reducing end, enabling the attachment of analytical labels through an anomeric ligation reaction. A nonasulfated tetrahyaluronan–ethylenediaminetetraacetic acid derivative has been produced and used as a paramagnetic tag for the elucidation of the complex of this ligand with interleukin‐10 using paramagnetic relaxation enhancement NMR analysis. The metal ion position is resolved with 1.0 Å, enabling a refined structural model of the complex. 相似文献