New oxy-sulfo-telluride glasses have been prepared in the Ge-Sb-Te-S-O system employing a two-step melting process which involves the processing of a chalcogenide glass (ChG) and subsequent melting with TeO2 or Sb2O3. The progressive incorporation of O at the expense of S was found to increase the density and the glass transition temperature and to decrease the molar volume of the investigated oxy-sulfo-telluride glasses. We also observed a shift of the vis-NIR cut-off wavelength to longer wavelength probably due to changes in Sb coordination within the glass matrix and overall matrix polarizability. Using Raman spectroscopy, correlations have been shown between the formation of Ge- and Sb-based oxysulfide structural units and the S/O ratio. Lastly, two glasses with similar composition (Ge20Sb6S64Te3O7) processed by melting the Ge23Sb7S70 glass with TeO2 or the Ge23Sb2S72Te4 glass with Sb2O3 were found to have slightly different physical, thermal, optical and structural properties. These changes are thought to result mainly from the higher moisture content and sensitivity of the TeO2 starting materials as compared to that of the Sb2O3. 相似文献
We present a two‐fold study designed to elucidate the adhesion mechanism of human U937 monocytes on novel N‐rich thin films deposited by plasma‐ and VUV photo‐polymerisation, so‐called “PVP:N” materials. It is shown that there exist sharply‐defined (“critical”) surface‐chemical conditions that are necessary to induce cell adhesion. By comparing the film chemistries at the “critical” conditions, we demonstrate the dominant role of primary amines in the cell adhesion mechanism. Quantitative real‐time RT‐PCR experiments using U937 cells that had adhered to PVP:N materials for up to 24 h are presented. The adhesion induces a transient expression of cytokines, markers of macrophage activation, as well as a more sustained expression of PPARγ and ICAM‐I.
In domain wall (DW) excitation experiments, nonlinearity (NL) intrinsic to the DW dynamics is often hard to distinguish from perturbation due to the confining potential or DW distortion. Here we numerically investigate the dynamic oscillations of magnetostatically coupled DWs: a system well understood in the quasistatic limit. NL is observed, even for a harmonic potential, due to the intrinsic DW motion. This behavior is principally dependent on terms normally associated with the DW canonical momentum and is in contrast with a NL restoring potential. This NL is not observable in quasistatic measurements, relatively insensitive to the confining potential, and may be tuned by the nanowire parameters. The shown NLs are present in any DW restoring potential and must be accounted for when probing DW potential landscapes. 相似文献
A new sustainable method is reported for the formation of aromatic carbon–heteroatom bonds under solvent-free and mild conditions (no co-oxidant, no strong acid and no toxic reagents) by using a new type of green ionic liquid. The bromination of methoxy arenes was chosen as a model reaction. The reaction methodology is based on only using natural sodium bromine, which is transformed into an electrophilic brominating reagent within an ionic liquid, easily prepared from the melted salt FeCl3 hexahydrate. Bromination reactions with this in-situ-generated reagent gave good yields and excellent regioselectivity under simple and environmentally friendly conditions. To understand the unusual bromine polarity reversal of sodium bromine without any strong oxidant, the molecular structure of the reaction medium was characterised by Raman and direct infusion electrospray ionisation mass spectroscopy (ESI-MS). An extensive computational investigation using density functional theory methods was performed to describe a mechanism that suggests indirect oxidation of Br− through new iron adducts. The versatility of the methodology was successively applied to nitration and thiocyanation of methoxy arenes using KNO3 and KSCN in melted hexahydrated FeCl3. 相似文献
Molecular platforms are regarded as promising candidates in the generation of units of information for quantum computing. Herein, a strategy combining spin-crossover metal ions and radical ligands is proposed from a model Hamiltonian first restricted to exchange interactions. Unusual spin states structures emerge from the linkage of a singlet/triplet commutable metal centre with two doublet-radical ligands. The ground state nature is modulated by charge transfers and can exhibit a mixture of triplet and singlet local metal spin states. Besides, the superposition reaches a maximum for , suggesting a necessary competition between the intramolecular and inter-metal-ligand and direct exchange interactions. The results promote spinmerism, an original manifestation of quantum entanglement between the spin states of a metal centre and radical ligands. The study provides insights into spin-coupled compounds and inspiration for the development of molecular spin-qubits. 相似文献
Increasing the mar resistance of OEM clear coats has been one of the main R&D priorities of paint manufacturers over the last years. Reaching a good mar resistance level without compromising other coating properties such as acid resistance proves to be a major challenge. We investigated the use of branched glycidyl esters in melamine based OEM acrylic formulations. Our results show that systems based on this type of esters lead to good overall coating properties as well as a good balance between acid and scratch resistance. 相似文献