A palladium-catalyzed
asymmetric Markovnikov hydroaminocarbonylation
of alkenes with anilines has been developed for the atom-economical
synthesis of 2-substituted propanamides bearing an α-stereocenter.
A novel phosphoramidite ligand L16 was discovered
which exhibited very high reactivity and selectivity in the reaction.
This asymmetric Markovnikov hydroaminocarbonylation employs
readily available starting materials and tolerates a wide range of
functional groups, thus providing a facile and straightforward method
for the regio- and enantioselective synthesis of 2-substituted
propanamides under ambient conditions. Mechanistic studies revealed
that the reaction proceeds through a palladium hydride pathway.
Stem
cells play a critical role in peripheral nerve regeneration.
Nerve scaffolds fabricated by specific materials can help induce the
neurogenic differentiation of stem cells. Therefore, it is a potential
strategy to enhance therapeutic efficiency. Graphene family nanomaterials
are widely applied in repairing peripheral nerves. However, the mechanism
underlying the pro-regeneration effects remains elusive. In this review,
we first discuss the properties of graphene family nanomaterials,
including monolayer and multilayer graphene, few-layer graphene, graphene
oxide, reduced graphene oxide, and graphene quantum dots. We also
introduce their applications in regulating stem cell differentiation.
Then, we review the potential mechanisms of the neurogenic differentiation
of stem cells facilitated by the materials. Finally, we discuss the
existing challenges in this field to advance the development of nerve
biomaterials.
Chalcogenide phase‐change materials (PCMs) have offered an appealing material solution by acting as a switchable dielectric layer to tune the electromagnetic properties of terahertz metamaterials and metasurfaces. Here, this work demonstrates large‐scale and lithography‐free manufacturing of all‐PCM terahertz metasurfaces based on direct laser switching of crystalline micro‐domains in a thin film with high switching ratio of the emerging plasmonic PCM, In3SbTe2 (IST). The fabricated high‐quality IST metasurfaces achieve efficient plasmonic resonances and a large modulation depth with ultrafast response (full width at half maxima of the modulation time ≈1.6 ps) in a deep‐subwavelength switching volume. For the dynamic evolution of terahertz resonance modes, theoretical modeling reveals a delicate interplay between amorphous and crystalline IST due to the bonding‐structure‐induced different carrier lifetimes and spatially localized electric fields. These studies open new avenues for realizing all‐PCM terahertz ultrafast nanophotonics.
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