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141.
142.
First-principles calculations are presented for the epitaxial-strain dependence of the ground-state phase stability of perovskite SrCoO(3). Through the combination of the large spin-phonon coupling with polarization-strain coupling and the coupling of the band gap to the polar distortion, both tensile and compressive epitaxial strain are seen to drive the bulk ferromagnetic-metallic (FM-M) phase to antiferromagnetic-insulating-ferroelectric (AFM-I-FE) phases, the latter having unusually low elastic energy. For compressive strain, there is a single coupled magnetic-ferroelectric metal-insulator transition. At this phase boundary, cross responses to applied electric and magnetic fields and stresses are expected. In particular, a magnetic field or compressive uniaxial stress applied to the AFM-FE(z) phase could induce an insulator-metal transition, and an electric field applied to the FM-M phase could induce a metal-insulator transition. 相似文献
143.
Teresa Burgahn Dr. Ruben Garrecht Dr. Kersten S. Rabe Prof. Dr. Christof M. Niemeyer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(14):3483-3488
We present a facile method for the combined synthesis and purification of protein-decorated DNA origami nanostructures (DONs). DONs bearing reductively cleavable biotin groups in addition to ligands for ligation of recombinant proteins are bound to magnetic beads. Protein immobilization is conducted with a large protein excess to achieve high ligation yields. Subsequent to cleavage from the solid support, pure sample solutions are obtained which are suitable for direct AFM analysis of occupation patterns. We demonstrate the method's utility using three different orthogonal ligation methods, the “halo-based oligonucleotide binder” (HOB), a variant of Halo-tag, the “SpyTag/SpyCatcher” (ST/SC) system, and the enzymatic “ybbR tag” coupling. We find surprisingly low efficiency for ST/SC ligation, presumably due to electrostatic repulsion and steric hindrance, whereas the ybbR method, despite its ternary nature, shows good ligation yields. Our method is particularly useful for the development of novel ligation methods and the synthesis of mechanically fragile DONs that present protein patterns for surface-based cell assays. 相似文献
144.
The new MOF Ga‐MIL‐53‐PDA [Ga(OH)(O2C‐C8H8‐CO2)] · H2O ( 1 ) was synthesized by a hydrothermal reaction of gallium nitrate, 1,4‐phenylenediacetic acid (H2PDA) and sodium hydroxide at 100 °C for 24 h. The product is a structural analogue of the archetypical MIL‐53 framework. Its crystal structure was determined by Rietveld refinement of powder X‐ray diffraction (PXRD) data. Furthermore 1,4‐phenylenedipropionic acid (H2PDP) was employed for further synthesis, which resulted in the dense layered coordination polymers [Ga2(OH)4(O2C‐C10H12‐CO2)] ( 2 ) and [Ga(OH)(O2C‐C10H12‐CO2)] ( 3 ), for which accurate structural models could be established. All compounds were fully characterized and tested regarding potential breathing behavior. Most remarkably, Ga‐MIL‐53‐PDA showed a subtle flexibility upon de/‐rehydration also confirming its porosity, but no drastic structural changes were observed. 相似文献
145.
A. Vollmer X. L. Feng X. Wang L. J. Zhi K. Müllen N. Koch J. P. Rabe 《Applied Physics A: Materials Science & Processing》2009,94(1):1-4
We demonstrate that graphene-based transparent and conductive thin films (GTCFs), fabricated by thermal reduction of graphite
oxide, have very similar electronic and structural properties as highly oriented pyrolytic graphite (HOPG). Electron spectroscopy
results suggest that the GTCFs are also semi-metallic and that the individual graphene sheets of the film are predominantly
oriented parallel to the substrate plane. These films may therefore be considered as a technologically relevant analogue to
HOPG electrodes, which cannot be easily processed into thin films. 相似文献
146.
Min Ai Susie Groeper Wei Zhuang Xi Dou Xinliang Feng Klaus Müllen Jürgen P. Rabe 《Applied Physics A: Materials Science & Processing》2008,90(2):277-283
Arrays of test structures consisting of sub-150 nm wide beams were lithographically fabricated in poly(methyl methacrylate)
(PMMA) and used to measure the elastic mechanical properties of the material. Capillary forces that arise during the drying
of rinse liquids from the test structures caused the nanoscale polymer beams to deform. The initial capillary forces were
defined by the test structure geometry, and the magnitudes of the forces were quantified using a two-dimensional Young–Laplace
equation. The deformation of the nanostructured beams was measured experimentally and compared to a model based on continuum-level
bending beam mechanics, thereby enabling the calculation of the Young’s modulus (E) of the material. For PMMA beams greater
than 100 nm in width E was calculated to be 5.1 GPa at room temperature, which corresponds closely to the elastic modulus
of bulk PMMA. The Young’s moduli of structures with dimensions less than 100 nm were measured to be less than the bulk value
and the origin of the decrease is discussed in terms of dimension dependent properties and polymer degradation during fabrication.
The polymer nanostructures also were determined to mechanically deform more readily with increasing characterization temperature.
PACS 62.25.+g; 68.35.Gy; 81.16.Nd 相似文献
147.
Flissikowski T Hundt A Lowisch M Rabe M Henneberger F 《Physical review letters》2001,86(14):3172-3175
Single-photon interference is observed on the ultranarrow long-term stable exciton resonance of an individual semiconductor quantum dot. This interference is related to the fine-structure splitting and allows direct conclusions about the coherence properties of the exciton. When selectively addressing a particular dot by quasiresonant phonon-assisted excitation, despite a rapid orientation relaxation on a 1-ps time scale, coherence is partly maintained. No significant further decoherence occurs when the ground state is reached until the exciton recombines radiatively (approximately 300 ps). 相似文献
148.
149.
150.
A prototypical single-molecule chemical-field-effect transistor is presented, in which the current through a hybrid-molecular diode is modified by nanometer-sized charge transfer complexes covalently linked to a molecule in an STM junction. The effect is attributed to an interface dipole which shifts the substrate work function by approximately 120 meV. It is induced by the complexes from electron acceptors covalently bound to the molecule in the gap and electron donors coming from the ambient fluid. This proof of principle is regarded as a major step towards monomolecular electronic devices. 相似文献