10 research outputs found
Quantification of Hybrid Topological Spin Textures and Their Nanoscale Fluctuations in Ferrimagnets
Noncolinear
spin textures, including chiral stripes and skyrmions,
have shown great potential in spintronics. Basic configurations of
spin textures are either Bloch or NeÌel types, and the intermediate
hybrid type has rarely been reported. A major challenge in identifying
hybrid spin textures is to quantitatively determine the hybrid angle,
especially in ferrimagnets with weak net magnetization. Here, we develop
an approach to quantify magnetic parameters, including chirality,
saturation magnetization, domain wall width, and hybrid angle with
sub-5 nm spatial resolution, based on Lorentz four-dimensional scanning
transmission electron microscopy (Lorentz 4D-STEM). We find strong
nanometer-scale variations in the hybrid angle and domain wall width
within structurally and chemically homogeneous FeGd ferrimagnetic
films. These variations fluctuate during different magnetization circles,
revealing intrinsic local magnetization inhomogeneities. Furthermore,
hybrid skyrmions can also be nucleated in FeGd films. These analyses
demonstrate that the Lorentz 4D-STEM is a quantitative tool for exploring
complex spin textures
Synthesis of Pincer Hydrido Ruthenium Olefin Complexes for Catalytic Alkane Dehydrogenation
A series
of new hydrido RuÂ(II) olefin complexes supported by isopropyl-substituted
pincer ligands have been synthesized and characterized. These complexes
are thermally robust and active for catalytic transfer and acceptorless
alkane dehydrogenation. Notably, the alkane dehydrogenation catalysts
are tolerant of a number of polar functional species
Influence of the concentration of seawater on the early hydration properties of calcium sulphoaluminate (CSA) cement: A preliminary study
This research investigates the effect of seawater of different concentrations on the hydration process and microstructure of calcium sulphoaluminate (CSA) cement. It studies the CSA cement pastes via experiments carried out to determine the initial and final setting times, mechanical strength and chemical shrinkage with X-ray diffraction (XRD), scanning electron microscopy (SEM) and simultaneous differential thermal-thermogravimetric (DTA-TG) analysis. The DTA-TG and XRD results showed that the main hydration products were ettringite (AFt) and aluminum hydroxide in the CSA cement paste mixed with both freshwater and seawater, while a small amount of ettringite (AFt) became monosulfate (AFm) in the freshwater-mixed CSA cement. The SEM results demonstrate that seawater can improve the microstructure of CSA cement paste in the early stage of hydration (1 d) but impairs the microstructure of the CSA cement matrix in the later stage of hydration (7 d). The experimental results also indicate that a high concentration of seawater can extend the setting time, increase the chemical shrinkage and decrease the mechanical strength of CSA cement
Rational design of peptide inhibitors targeting HSP90âCDC37 proteinâprotein interaction
Supplementary NMR spec data</p
Point-of-Use SERS Approach for Efficient Determination and Removal of Phthalic Acid Esters Based on a MetalâOrganic Framework-Coated Melamine Sponge
Phthalic
acid esters (PAEs) are ubiquitous environmental contaminants,
and their real-time monitoring and removal remain challenging. Herein,
a point-of-use (POU) device integrating adsorption, surface-enhanced
Raman spectroscopy (SERS), and removal strategy was developed and
realized ultrafast on-site determination of PAEs and cleanup of them
from water. A piece of flexible melamine sponge (MS) was coated with
gold nanostars (AuNSs) and metalâorganic frameworks (MOFs),
thus obtaining SERS activity and adsorption capacity. Based on this
multifunctional AuNSs@MOFs/MS composite, clear trends were observed
between SERS signal intensity and concentration of di(2-ethylhexyl)phthalate
(DEHP) and dibutyl phthalate (DBP). The method detection limits of
DEHP and DBP were calculated to be 0.75 Ă 10â7 and 0.67 Ă 10â7 M in water, respectively,
proving good sensitivity. Furthermore, this POU device exhibited satisfactory
adsorption capacity (âŒ82.3 g/g for DBP and âŒ90.0 g/g
for DEHP), high adsorption efficiency (equilibrium in 100 s), and
good regeneration capability (removal efficiency >70% after 5 cycles).
The applicability of this device was verified by its good determination
and removal performance in real environmental water matrices. The
whole process could be completed within 5 min. This approach provides
a new POU alternative for real-time monitoring and removal of PAEs
in water
Sulfur-Doped NiFe Hydroxide Nanobowls with Wrinkling Patterns for Photothermal Cancer Therapy
Hierarchical
multiscale wrinkling nanostructures have shown great
promise for many biomedical applications, such as cancer diagnosis
and therapy. However, synthesizing these materials with precise control
remains challenging. Here, we report a sulfur doping strategy to synthesize
sub-1 nm NiFe hydroxide ultrathin nanosheets (S-NiFe HUNs). The introduction
of sulfur affects the reduction of the band gap and the adjustment
of the electronic structure, thereby improving the light absorption
ability of the S-NiFe HUNs. Additionally, S-NiFe HUNs show a multilayered
nanobowl-like structure that enables multiple reflections of incident
light inside the nanostructure, which improved the utilization of
incident light and achieved high photothermal conversion. As a result,
the as-prepared product with hydrophilic modification (dS-NiFe HUNs)
demonstrated enhanced tumor-killing ability in vitro. In a mouse model of breast cancer, dS-NiFe HUNs combined with near-infrared
light irradiation greatly inhibited tumor growth and prolonged the
mice survival. Altogether, our study demonstrates the great potential
of dS-NiFe HUNs for cancer photothermal therapy applications
Exploring the Complex Impact of Proteins on Dopamine Polymerization: Mechanisms and Strategies for Modulation
Polydopamine (pDA) is a valuable material with wide-ranging
potential
applications. However, the complex and debated nature of dopamine
polymerization complicates our understanding. Specifically, the impact
of foreign substances, especially proteins, on pDA formation adds
an additional layer of subtlety and complexity. This study delves
into specific surface features of proteins that predominantly shape
their impact on dopamine polymerization. Notably, the biotin-binding
site emerges as a critical region responsible for the pronounced inhibitory
effect of avidin and neutravidin on the dopamine polymerization process.
The binding of biotin successfully mitigates these inhibitory effects.
Moreover, several nucleases demonstrated a significant hindrance to
pDA formation, with their impact substantially alleviated through
the introduction of DNA. It is speculated that hydrogen bonding, electrostatic,
cationâÏ, and/or hydrophobic interactions may underlie
the binding between protein surfaces and diverse oligomeric intermediates
formed by the oxidation products of dopamine. Additionally, we observed
a noteworthy blocking effect on the dopamine polymerization reaction
induced by erythropoietin (EPO), a glycoprotein hormone known for
its role in stimulating red blood cell production and demonstrating
neuroprotective effects. The inhibitory influence of EPO persisted
even after deglycosylation. These findings not only advance our comprehension
of the mechanisms underlying dopamine polymerization but also provide
strategic insights for manipulating the reaction to tailor desired
biomaterials
Density Measurements of Various Molten Sodium, Magnesium, Potassium, and Uranium Chloride Salt Compositions Using Neutron Imaging
With an increased interest in the use of molten salts
for energy
generation, obtaining thermophysical properties of salt mixtures becomes
critical for the understanding of salt performance and behavior. Density
is one of the significant thermophysical properties of salt systems.
This work presents the density measurement of molten chloride salt
mixtures using neutron imaging. This work was performed at the Oak
Ridge National Laboratory High-Flux Isotope Reactor. Resulting densities
as a function of temperature for different molten chloride salts from
this work were compared with calculated values using RedlichâKister
modeling. Agreement between the calculated and measured values was
within 1â10%, with the exception of the ternary UCl3âNaClâKCl salt that showed a 32% discrepancy between
several literature reports; however, the results did align well with
another neutron radiography article. Analysis of the radiographs suggests
that microbubbles in the ternary mixture might have biased the density
measurements
Expanding the Scope of Polymerization-Induced Self-Assembly: ZâRAFT-Mediated Photoinitiated Dispersion Polymerization
In
this communication, we developed the first well-controlled Z-RAFT
(RAFT = reversible additionâfragmentation chain transfer) mediated
polymerization-induced self-assembly (PISA) formulation based on photoinitiated
RAFT dispersion polymerization of <i>tert</i>-butyl acrylate
(<i>t</i>BA) in ethanol/water (60/40, w/w) at room temperature
using a Z-type macromolecular chain transfer agent (macro-CTA). Polymerizations
proceeded rapidly via the exposure of visible-light irradiation (405
nm, 0.45 mW/cm<sup>2</sup>) with high monomer conversion (>95%)
being
achieved within 1 h. A variety of polymer nano-objects (spheres, worms,
and vesicles) with narrow molar mass distributions were prepared by
this Z-RAFT mediated PISA formulation. Silver nanoparticles were loaded
with the vesicles via in situ reduction, which can be used as a catalyst
for the reduction of methylene blue (MB) in the presence of NaBH<sub>4</sub>. Finally, gel permeation chromatography (GPC) analysis demonstrated
that the corona block and the core-forming block could be cleaved
by treating with excess initiator. This novel PISA formulation will
greatly expand the scope of PISA and provide more mechanistic insights
into the PISA research
Multimodal Encapsulation to Selectively Permeate Hydrogen and Engineer Channel Conduction for pâType SnO<sub><i>x</i></sub> Thin-Film Transistor Applications
It has been challenging to synthesize p-type SnOx (1 x < 2) and engineer
the electrical
properties such as carrier density and mobility due to the narrow
processing window and the localized oxygen 2p orbitals near the valence
band. Herein, we report on the multifunctional encapsulation of p-SnOx to limit the surface adsorption of oxygen
and selectively permeate hydrogen into the p-SnOx channel for thin-film transistor (TFT) applications. Time-of-flight
secondary ion mass spectrometry (ToF-SIMS) measurements identified
that ultrathin SiO2 as a multifunctional encapsulation
layer effectively suppressed the oxygen adsorption on the back channel
surface of p-SnOx and selectively diffused
hydrogen across the entire thickness of the channel. Encapsulated
p-SnOx-based TFTs demonstrated much enhanced
channel conductance modulation in response to the gate bias applied,
featuring higher on-state current and lower off-state current (on/off
ratio > 103), field effect mobility of 3.41 cm2/(V s), and threshold voltages of âŒ5â10 V. The fabricated
devices show minimal deviations as small as ±6% in the TFT performance
parameters, which demonstrates good reproducibility of the fabrication
process. The relevance between the TFT performance and the effects
of hydrogen permeation is discussed in regard to the intrinsic and
extrinsic doping mechanisms. Density functional theory calculations
reveal that hydrogen-related impurity complexes are in charge of the
enhanced channel conductance with gate biases, which further supports
the selective permeation of hydrogen through a thin SiO2 encapsulation