Half metal, with moderate delocalized and parallelized arrangement of spin freedom, is crucial to optimize the bifunctional catalyst for both ORR and OER, and the atomic magnetization on the reaction center could serve as a activity descriptor.
Durable and biocompatible superhydrophobic surfaces are of significant potential use in biomedical applications. Here, a nonfluorinated, elastic, superhydrophobic film that can be used for medical wound dressings to enhance their hemostasis function is introduced. The film is formed by titanium dioxide nanoparticles, which are chemically crosslinked in a poly(dimethylsiloxane) (PDMS) matrix. The PDMS crosslinks result in large strain elasticity of the film, so that it conforms to deformations of the substrate. The photocatalytic activity of the titanium dioxide provides surfaces with both self‐cleaning and antibacterial properties. Facile coating of conventional wound dressings is demonstrated with this composite film and then resulting improvement for hemostasis. High gas permeability and water repellency of the film will provide additional benefit for medical applications.
Coatings with low sliding angles for liquid drops have a broad range of applications. However, it remains a challenge to have a fast, easy, and universal preparation method for coatings that are long‐term stable, robust, and environmentally friendly. Here, a one‐step grafting‐from approach is reported for poly(dimethylsiloxane) (PDMS) brushes on surfaces through spontaneous polymerization of dichlorodimethylsilane fulfilling all these requirements. Drops of a variety of liquids slide off at tilt angles below 5°. This non‐stick coating with autophobicity can reduce the waste of water and solvents in cleaning. The strong covalent attachment of the PDMS brush to the substrate makes them mechanically robust and UV‐tolerant. Their resistance to high temperatures and to droplet sliding erosion, combined with the low film thickness (≈8 nm) makes them ideal candidates to solve the long‐term degradation issues of coatings for heat‐transfer surfaces.
Zero-dimensional hybrid manganese
halides with the type-I band
alignment between the manganese halide tetrahedra and organic matrices
have attracted much attention as highly efficient narrow-band green
emitters. Herein we study the photoluminescence (PL) behavior of hybrid
manganese bromides with type-II band alignment, where the lowest unoccupied
molecular orbital (LUMO) level can be tuned by employing quaternary
phosphonium dications with different degrees of conjugation. For low-conjugated
organic matrices, the band alignment can shift from type II in the
ground state to type I in the excited state, which enables high photoluminescence
quantum yields. In contrast, for high-conjugated organic matrices,
the band alignment cannot convert to type I in the excited state because
the LUMO lies too low, and thus, the excited electrons are transferred
from the tetrahedra to the matrices, which leads to severe PL quenching.
Our results show the importance of the excited-state band alignment
for understanding the PL behavior of hybrid metal halide semiconductors.
Antifreeze proteins
(AFPs) and glycoproteins (AFGPs) are exemplary
at modifying ice crystal growth and at inhibiting ice recrystallization
(IRI) in frozen solutions. These properties make them highly attractive
for cold storage and cryopreservation applications of biological tissue,
food, and other water-based materials. The specific requirements for
optimal cryostorage remain unknown, but high IRI activity has been
proposed to be crucial. Here, we show that high IRI activity alone
is insufficient to explain the beneficial effects of AF(
G
)Ps on human red blood cell (hRBC) survival. We show that AF(
G
)Ps with different IRI activities cause similar cell recoveries
of hRBCs and that a modified AFGP variant with decreased IRI activity
shows increased cell recovery. The AFGP variant was found to have
enhanced interactions with a hRBC model membrane, indicating that
the capability to stabilize cell membranes is another important factor
for increasing the survival of cells after cryostorage. This information
should be considered when designing novel synthetic cryoprotectants.
Antifreeze glycoproteins
(AFGPs) are able to bind to ice, halt
its growth, and are the most potent inhibitors of ice recrystallization
known. The structural basis for AFGP’s unique properties remains
largely elusive. Here we determined the antifreeze activities of AFGP
variants that we constructed by chemically modifying the hydroxyl
groups of the disaccharide of natural AFGPs. Using nuclear magnetic
resonance, two-dimensional infrared spectroscopy, and circular dichroism,
the expected modifications were confirmed as well as their effect
on AFGPs solution structure. We find that the presence of all the
hydroxyls on the disaccharides is a requirement for the native AFGP
hysteresis as well as the maximal inhibition of ice recrystallization.
The saccharide hydroxyls are apparently as important as the acetyl
group on the galactosamine, the α-linkage between the disaccharide
and threonine, and the methyl groups on the threonine and alanine.
We conclude that the use of hydrogen-bonding through the hydroxyl
groups of the disaccharide and hydrophobic interactions through the
polypeptide backbone are equally important in promoting the antifreeze
activities observed in the native AFGPs. These important criteria
should be considered when designing synthetic mimics.
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