Highly active bulk transition-metal phosphides (WP, MoP, and Ni 2 P) were synthesized for the catalytic hydrodeoxygenation of palmitic acid, hexadecanol, hexadecanal, and microalgae oil. The specific activities positively correlated with the concentration of exposed metal sites, although the relative rates changed with temperature due to activation energies varying from 57 kJ mol −1 for MoP to 142 kJ mol −1 for WP. The reduction of the fatty acid to the aldehyde occurs through a Langmuir−Hinshelwood mechanism, where the rate-determining step is the addition of the second H to the hydrocarbon. On WP, the conversion of palmitic acid proceeds via R-) was an important pathway on MoP and Ni 2 P. Conversion via dehydration to a ketene, followed by its decarbonylation, occurred only on Ni 2 P. The rates of alcohol dehydration (R-CH 2 CH 2 OH → R-CHCH 2 ) correlate with the concentrations of Lewis acid sites of the phosphides.
Here, we present an approach to model and adapt the mechanical regulation of morphogenesis that uses contractile cells as sculptors of engineered tissue anisotropy in vitro. Our method uses heterobifunctional cross-linkers to create mechanical boundary constraints that guide surface-directed sculpting of cell-laden extracellular matrix hydrogel constructs. Using this approach, we engineered linearly aligned tissues with structural and mechanical anisotropy. A multiscale in silico model of the sculpting process was developed to reveal that cell contractility increases as a function of principal stress polarization in anisotropic tissues. We also show that the anisotropic biophysical microenvironment of linearly aligned tissues potentiates soluble factor-mediated tenogenic and myogenic differentiation of mesenchymal stem cells. The application of our method is demonstrated by (i) skeletal muscle arrays to screen therapeutic modulators of acute oxidative injury and (ii) a 3D microphysiological model of lung cancer cachexia to study inflammatory and oxidative muscle injury induced by tumor-derived signals.
Copper‐oxo clusters exchanged in zeolite mordenite are active in the stoichiometric conversion of methane to methanol at low temperatures. Here, we show an unprecedented methanol yield per Cu of 0.6, with a 90–95 % selectivity, on a MOR solely containing [Cu3(μ‐O)3]2+ active sites. DFT calculations, spectroscopic characterization and kinetic analysis show that increasing the chemical potential of methane enables the utilization of two μ‐oxo bridge oxygen out of the three available in the tricopper‐oxo cluster structure. Methanol and methoxy groups are stabilized in parallel, leading to methanol desorption in the presence of water.
Cu-zeolites are able
to directly convert methane to methanol via
a three-step process using O
2
as oxidant. Among the different
zeolite topologies, Cu-exchanged mordenite (MOR) shows the highest
methanol yields, attributed to a preferential formation of active
Cu–oxo species in its 8-MR pores. The presence of extra-framework
or partially detached Al species entrained in the micropores of MOR
leads to the formation of nearly homotopic redox active Cu–Al–oxo
nanoclusters with the ability to activate CH
4
. Studies
of the activity of these sites together with characterization by
27
Al NMR and IR spectroscopy leads to the conclusion that the
active species are located in the 8-MR side pockets of MOR, and it
consists of two Cu ions and one Al linked by O. This Cu–Al–oxo
cluster shows an activity per Cu in methane oxidation significantly
higher than of any previously reported active Cu–oxo species.
In order to determine unambiguously the structure of the active Cu–Al–oxo
cluster, we combine experimental XANES of Cu K- and L-edges, Cu K-edge
HERFD-XANES, and Cu K-edge EXAFS with TDDFT and AIMD-assisted simulations.
Our results provide evidence of a [Cu
2
AlO
3
]
2+
cluster exchanged on MOR Al pairs that is able to oxidize
up to two methane molecules per cluster at ambient pressure.
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