Bimetallic Ru-Ni and Rh-Ni nanocatalysts coated with a phase transfer agent efficiently cleave aryl ether C-O linkages in water in the presence of hydrogen. For dimeric substrates with weaker C-O ...linkages,
α-
-4 and β-
-4 bonds, low loadings of the precious metal (Rh or Ru) in the nanocatalysts quantitatively afford monomers, whereas for the stronger 4-
-5 linkage higher amounts of the precious metal are required to achieve complete conversion. Under the optimized, relatively mild operating conditions, the C-O bonds in a range of substituted ether compounds are efficiently cleaved, and mechanistic insights into the reaction pathways are provided. This work paves the way to sustainable approaches for the hydrogenolysis of C-O bonds.
We present two open-source Python packages: “electron spectro-microscopy” (espm) and “electron microscopy tables” (emtables). The espm software enables the simulation of scanning transmission ...electron microscopy energy-dispersive X-ray spectroscopy datacubes, based on user-defined chemical compositions and spatial abundance maps of constituent phases. The simulation process uses X-ray emission cross-sections generated via state-of-the-art calculations made with emtables. These tables are designed to be easily modifiable, either manually or using espm. The simulation framework is designed to test the application of decomposition algorithms for the analysis of STEM-EDX spectrum images with access to a known ground truth. We validate our approach using the case of a complex geology-related sample, comparing raw simulated and experimental datasets and the outputs of their non-negative matrix factorization. In addition to testing machine learning algorithms, our packages will also help experimental design, for instance, predicting dataset characteristics or establishing minimum counts needed to measure nanoscale features.
•We introduce two packages for fast simulation of analytical electron microscopy data.•emtables produces editable and human-readable X-ray emission tables.•espm simulates scanning transmission electron microscopy X-ray spectrum images.•Simulated spectrum images bear a strong resemblance to experimental data.•Softwares are open-source, Python-based and integrated into HyperSpy framework.
Thin films of the solid solution Nd1-xLaxNiO
are grown in order to study the expected 0 K phase transitions at a specific composition. We experimentally map out the structural, electronic and ...magnetic properties as a function of
and a discontinuous, possibly first order, insulator-metal transition is observed at low temperature when
= 0.2. Raman spectroscopy and scanning transmission electron microscopy show that this is not associated with a correspondingly discontinuous global structural change. On the other hand, results from density functional theory (DFT) and combined DFT and dynamical mean field theory calculations produce a 0 K first order transition at around this composition. We further estimate the temperature-dependence of the transition from thermodynamic considerations and find that a discontinuous insulator-metal transition can be reproduced theoretically and implies a narrow insulator-metal phase coexistence with
. Finally, muon spin rotation (
SR) measurements suggest that there are non-static magnetic moments in the system that may be understood in the context of the first order nature of the 0 K transition and its associated phase coexistence regime.
Nanometer wide silicon filaments embedded in an amorphous silicon oxide matrix are grown at low temperatures over a large area. The optical and electrical properties of these mixed‐phase ...nanomaterials can be tuned independently, allowing for advanced light management in high efficiency thin‐film silicon solar cells and for band‐gap tuning via quantum confinement in third‐generation photovoltaics.
In biological environments, the surface of nanoparticles (NPs) are modified by protein corona (PC) that determines their biological behavior. Unfortunately, in vitro tests still give different PC ...than in vivo tests causing in vitro–in vivo discrepancy; hence, in vitro studies are not indicative for the NPs' behavior in vivo. Here is demonstrated that PC in vitro is strongly influenced by the type of extracellular fluid (ECF), blood or lymph, by their high and low flow conditions and transitions between ECFs, and a combination of these parameters. As a result, this in vitro study approaches fluidic and dynamic variations to which NPs are exposed in vivo: different ECF that NPs encounter first in different injection routes, different transitions in‐between ECFs during circulation, and simultaneous change in the exposed flow in these transitions. The most‐abundant proteins in PCs are found to be not the most abundant in ECFs, but those having high affinity for binding to the surface of NPs. Moreover, some proteins are differently abundant in PCs at different flows, which indicate force‐promoted binding, catch bonds. These results suggest that future in vitro studies should consider more complex incubation conditions to improve the in vitro–in vivo consistency necessary for translational research.
Protein corona of lymph versus blood under different flow conditions, and transition from one extracellular fluid to another are studied. Simultaneous inclusion of these novel parameters leads to dramatic changes in the protein corona. Preferentially bound proteins are rich in chemical groups with high affinities for binding to the surface of nanoparticles.
The ability to obtain three-dimensional (3-D) information about morphologies of nanostructures elucidates many interesting properties of materials in both physical and biological sciences. Here we ...demonstrate a novel method in scanning transmission electron microscopy (STEM) that gives a fast and reliable assessment of the 3-D configuration of curvilinear nanostructures, all without needing to tilt the sample through an arc. Using one-dimensional crystalline defects known as dislocations as a prototypical example of a complex curvilinear object, we demonstrate their 3-D reconstruction two orders of magnitude faster than by standard tilt-arc TEM tomographic techniques, from data recorded by selecting different ray paths of the convergent STEM probe. Due to its speed and immunity to problems associated with a tilt arc, the tilt-less 3-D imaging offers important advantages for investigations of radiation-sensitive, polycrystalline, or magnetic materials. Further, by using a segmented detector, the total electron dose is reduced to a single STEM raster scan acquisition; our tilt-less approach will therefore open new avenues for real-time 3-D electron imaging of dynamic processes.
One of the most widely used materials for bone graft substitution is β‐Tricalcium phosphate (β‐TCP; β-Ca3(PO4)2). β-TCP is typically produced by sintering in air or vacuum. During this process, ...evaporation of phosphorus (P) species occurs, leading to the formation of a calcium-rich alkaline layer. It was recently shown that the evaporation of P species could be prevented by co-sintering β-TCP with dicalcium phosphate (DCPA; CaHPO4; mineral name: monetite). The aim of this study was to see how a change of sintering atmosphere could affect the physico-chemical and biological properties of β-TCP. For this purpose, three experimental groups were considered: β‐TCP cylinders sintered in air and subsequently polished to remove the surface layer (control group); the same polished cylinders after subsequent annealing at 500 °C in air to generate a calcium-rich alkaline layer (annealed group); and finally, β‐TCP cylinders sintered in a monetite-rich atmosphere and subsequently polished (monetite group). XPS analysis confirmed that cylinders from the annealed group had a significantly higher Ca/P molar ratio at their surface than that of the control group while this ratio was significantly lower for the cylinders from the monetite group. Sintering β‐TCP in the monetite-rich atmosphere significantly reduced the grain size and increased the density. Changes of surface composition affected the activity of osteoclasts seeded onto the surfaces, since annealed β-TCP cylinders were significantly less resorbed than β-TCP cylinders sintered in the monetite-rich atmosphere. This suggests that an increase of the surface Ca/P molar ratio leads to a decrease of osteoclastic resorption.
Minimal changes of surface and bulk (< 1%) composition have major effects on the ability of osteoclasts to resorb β-tricalcium phosphate (β-TCP), one of the most widely used ceramics for bone substitution. The results presented in this study are thus important for the calcium phosphate community because (i) β-TCP may have up to 5% impurities according to ISO and ASTM standards and still be considered to be “pure β-TCP”, (ii) β-TCP surface properties are generally not considered during biocompatibility assessment and (iii) a rationale can be proposed to explain the various inconsistencies reported in the literature on the biological properties of β-TCP.
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